Science.gov

Sample records for ii core complexes

  1. Fast isolation of highly active photosystem II core complexes from spinach.

    PubMed

    Wang, Zhao-Gai; Xu, Tian-Hua; Liu, Cheng; Yang, Chun-Hong

    2010-09-01

    Purification of photosystem II (PSII) core complexes is a time-consuming and low-efficiency process. In order to isolate pure and active PSII core complexes in large amounts, we have developed a fast method to isolate highly active monomeric and dimeric PSII core complexes from spinach leaves by using sucrose gradient ultracentrifugation. By using a vertical rotor the process was completed significantly faster compared with a swing-out rotor. In order to keep the core complexes in high activity, the whole isolation procedure was performed in the presence of glycine betain and pH at 6.3. The isolated pigment-protein complexes were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, absorption spectroscopy, 77 K fluorescence spectroscopy and high performance liquid chromatography. Our results show that this method is a better choice for quick and efficient isolation of functionally active PSII core complexes. PMID:20738723

  2. Charge separation and energy transfer in the photosystem II core complex studied by femtosecond midinfrared spectroscopy.

    PubMed

    Pawlowicz, N P; Groot, M-L; van Stokkum, I H M; Breton, J; van Grondelle, R

    2007-10-15

    The core of photosystem II (PSII) of green plants contains the reaction center (RC) proteins D1D2-cytb559 and two core antennas CP43 and CP47. We have used time-resolved visible pump/midinfrared probe spectroscopy in the region between 1600 and 1800 cm(-1) to study the energy transfer and charge separation events within PSII cores. The absorption difference spectra in the region of the keto and ester chlorophyll modes show spectral evolution with time constants of 3 ps, 27 ps, 200 ps, and 2 ns. Comparison of infrared (IR) difference spectra obtained for the isolated antennas CP43 and CP47 and the D1D2-RC with those measured for the PSII core allowed us to identify the features specific for each of the PSII core components. From the presence of the CP43 and CP47 specific features in the spectra up to time delays of 20-30 ps, we conclude that the main part of the energy transfer from the antennas to the RC occurs on this timescale. Direct excitation of the pigments in the RC evolution associated difference spectra to radical pair formation of PD1+PheoD1- on the same timescale as multi-excitation annihilation and excited state equilibration within the antennas CP43 and CP47, which occur within approximately 1-3 ps. The formation of the earlier radical pair ChlD1+PheoD1-, as identified in isolated D1D2 complexes with time-resolved mid-IR spectroscopy is not observed in the current data, probably because of its relatively low concentration. Relaxation of the state PD1+PheoD1-, caused by a drop in free energy, occurs in 200 ps in closed cores. We conclude that the kinetic model proposed earlier for the energy and electron transfer dynamics within the D1D2-RC, plus two slowly energy-transferring antennas C43 and CP47 explain the complex excited state and charge separation dynamics in the PSII core very well. We further show that the time-resolved IR-difference spectrum of PD1+PheoD1- as observed in PSII cores is virtually identical to that observed in the isolated D1D2-RC

  3. 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. PMID:26911647

  4. Substrate water exchange in photosystem II core complexes of the extremophilic red alga Cyanidioschyzon merolae.

    PubMed

    Nilsson, Håkan; Krupnik, Tomasz; Kargul, Joanna; Messinger, Johannes

    2014-08-01

    The binding affinity of the two substrate-water molecules to the water-oxidizing Mn₄CaO₅ catalyst in photosystem II core complexes of the extremophilic red alga Cyanidioschyzon merolae was studied in the S₂ and S₃ states by the exchange of bound ¹⁶O-substrate against ¹⁸O-labeled water. The rate of this exchange was detected via the membrane-inlet mass spectrometric analysis of flash-induced oxygen evolution. For both redox states a fast and slow phase of water-exchange was resolved at the mixed labeled m/z 34 mass peak: kf=52 ± 8s⁻¹ and ks=1.9 ± 0.3s⁻¹ in the S₂ state, and kf=42 ± 2s⁻¹ and kslow=1.2 ± 0.3s⁻¹ in S₃, respectively. Overall these exchange rates are similar to those observed previously with preparations of other organisms. The most remarkable finding is a significantly slower exchange at the fast substrate-water site in the S₂ state, which confirms beyond doubt that both substrate-water molecules are already bound in the S2 state. This leads to a very small change of the affinity for both the fast and the slowly exchanging substrates during the S₂→S₃ transition. Implications for recent models for water-oxidation are briefly discussed. PMID:24726350

  5. A zeaxanthin-independent nonphotochemical quenching mechanism localized in the photosystem II core complex.

    PubMed

    Finazzi, Giovanni; Johnson, Giles N; Dall'Osto, Luca; Dallosto, Luca; Joliot, Pierre; Wollman, Francis-André; Bassi, Roberto

    2004-08-17

    Illumination of dark-adapted barley plants with low light transiently induced a large nonphotochemical quenching of chlorophyll fluorescence. This reaction was identified as a form of high-energy-state quenching. Its appearance was not accompanied by zeaxanthin synthesis but was associated with a reversible inactivation of a fraction of photosystem II (PSII) centers. Both the fluorescence quenching and PSII inactivation relaxed in parallel with the activation of the Calvin cycle. We interpret the induction of this phenomenon as due to the generation of a quenched state in the PSII core complex. This reaction is probably caused by the transient overacidification of the thylakoid lumen, whereas its dissipation results from the relaxation of both the pH gradient across the thylakoid membrane and redox pressure upon activation of carbon fixation. At saturating light intensities, inactivation of PSII was still observed at the onset of illumination, although its recovery did not result in dissipation of high-energy quenching, which presents typical characteristics of an antenna-associated quenching at steady state. Reaction-center quenching seems therefore to be a common transient feature during illumination, being replaced by other phenomena (photochemical or antenna quenching and photoinhibition), depending on the balance between light and carbon fixation fluxes. PMID:15304641

  6. Fluorescence studies of cyanobacterial phycobiliproteins: I. Spectroscopy of allophycocyanin core complexes. II. Spectroscopy of two phycobilisome core insertion mutants

    SciTech Connect

    Maxson, P.

    1988-10-01

    The work described here relates to the mechanisms governing energy transfer in the core polypeptides of the cyanobacterial phycobilisome. Two approaches are represented: measurements were made on isolated core components for which a great deal of structural information is available; and the fluorescence properties were characterized for the whole phycobilisome from two phycobilisome core insertion mutants. 130 refs.

  7. 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.

  8. 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

  9. Complex coacervate core micelles.

    PubMed

    Voets, Ilja K; de Keizer, Arie; Cohen Stuart, Martien A

    2009-01-01

    In this review we present an overview of the literature on the co-assembly of neutral-ionic block, graft, and random copolymers with oppositely charged species in aqueous solution. Oppositely charged species include synthetic (co)polymers of various architectures, biopolymers - such as proteins, enzymes and DNA - multivalent ions, metallic nanoparticles, low molecular weight surfactants, polyelectrolyte block copolymer micelles, metallo-supramolecular polymers, equilibrium polymers, etcetera. The resultant structures are termed complex coacervate core/polyion complex/block ionomer complex/interpolyelectrolyte complex micelles (or vesicles); i.e., in short C3Ms (or C3Vs) and PIC, BIC or IPEC micelles (and vesicles). Formation, structure, dynamics, properties, and function will be discussed. We focus on experimental work; theory and modelling will not be discussed. Recent developments in applications and micelles with heterogeneous coronas are emphasized. PMID:19038373

  10. Light-induced voltage changes associated with electron and proton transfer in photosystem II core complexes reconstituted in phospholipid monolayers.

    PubMed Central

    Höök, F; Brzezinski, P

    1994-01-01

    We have measured light-induced voltage changes (electrogenic events) in photosystem II (PSII) core complexes oriented in phospholipid monolayers. These events are compared to those measured in the functionally and structurally closely related reaction centers from the photosynthetic bacterium Rhodobacter sphaeroides. In both systems we observed a rapid (< 100 ns) light-induced increase in voltage associated with charge separation. In PSII reaction centers it was followed by a decrease (decay) of approximately 14% of the charge-separation voltage and a time constant of approximately 500 microseconds. In bacterial reaction centers this decay was approximately 9% of the charge-separation voltage, and the time constant was approximately 200 microseconds. The decay was presumably associated with a structural change. In bacterial reaction centers, in the presence of excess water-soluble cytochrome c2+, it was followed by a slower increase of approximately 30% of the charge-separation voltage, associated with electron transfer from the cytochrome to the oxidized donor, P+. In PSII reaction centers, after the decay the voltage remained on the same level for > or = 0.5 s. In PSII reaction centers the electron transfer Q-AQB-->QA Q-B contributed with an electrogenicity of < or = 5% of that of the charge separation. In bacterial reaction centers this electrogenicity was < or = 2% of the charge-separation electrogenicity. Proton transfer to Q2-B in PSII reaction centers contributed with approximately 5% of the charge-separation voltage, which is approximately a factor of three smaller than that observed in bacterial reaction centers. PMID:8075340

  11. Assignment of the gene for the core protein II (UQCRC2) subunit of the mitochondrial cytochrome bc[sub 1] complex to human chromosome 16p12

    SciTech Connect

    Duncan, A.M.V. Kingston General Hospital ); Ozawa, Takayuki; Suzuki, Hiroshi ); Rozen, R. Montreal Children's Hospital )

    1993-11-01

    The mammalian cytochrome be[sub 1] complex (complex III) of the mitochondrial respiratory chain catalyzes electron transfer from ubiquinol to cytochrome c. The complex consists of 10-11 subunits: Core proteins I and II, cytochromes b and c[sub 1], the Rieske iron-sulfur protein, the ubiquinone-binding protein, the hinge protein, and 3-4 subunits of low molecular weight. Cytochrome b is encoded by the mitochondrial genome; the other subunits are encoded by nuclear genes. Both the human cytochrome c[sub 1] and the human ubiquinone-binding protein subunits have been assigned to chromosome 8 by somatic cell hybrid mapping. In this study, the authors used in situ hybridization to map core protein II. In situ hybridization to BrdU-synchronized peripheral blood lymphocytes was performed using the method of Harper and Saunders. Chromosomes were stained with a modified fluorescence, 0.25% Wright's stain procedure. The positions of silver grains directly over or touching well-banded metaphase chromosomes were mapped to an ISCN idiogram. The analysis of the distribution of 200 silver grams following in situ hybridization revealed a significant clustering of grains in the p12 region of chromosome 16. The assignment of the core II subunit to human chromosome 16p12 confirms that it is encoded by the nuclear, rather than the mitochondrial, genome. The identification of a single strong hybridization signal is indicative of one locus with no pseudogenes. 6 refs., 1 fig.

  12. Star-forming regions of the Aquila rift cloud complex. II. Turbulence in molecular cores probed by NH3 emission

    NASA Astrophysics Data System (ADS)

    Levshakov, S. A.; Henkel, C.; Reimers, D.; Wang, M.

    2014-07-01

    Aims: We intend to derive statistical properties of stochastic gas motion inside the dense, low-mass star-forming molecular cores that are traced by NH3(1, 1) and (2, 2) emission lines. Methods: We use the spatial two-point autocorrelation (ACF) and structure functions calculated from maps of the radial velocity fields. Results: The observed ammonia cores are characterized by complex intrinsic motions of stochastic nature. The measured kinetic temperature ranges between 8.8 K and 15.1 K. From NH3 excitation temperatures of 3.5-7.3 K, we determine H2 densities with typical values of nH2~ (1-6) × 104 cm-3. The ammonia abundance, X = [NH3]/[H2], varies from 2 × 10-8 to 1.5 × 10-7. We find oscillating ACFs, which eventually decay to zero with increasing lags on scales of 0.04 ≲ ℓ ≲ 0.5 pc. The current paradigm supposes that the star-formation process is controlled by the interplay between gravitation and turbulence with the latter preventing molecular cores from a rapid collapse due to their own gravity. Thus, oscillating ACFs may indicate a damping of the developed turbulent flows surrounding the dense but less turbulent core, a transition to dominating gravitational forces and, hence, to gravitational collapse. Appendix A is available in electronic form at http://www.aanda.org

  13. Palladium (II) Hydrazopyrazolone Complexes

    NASA Astrophysics Data System (ADS)

    El-Maraghy, Salah B.; Salib, K. A.; Stefan, Shaker L.

    1989-12-01

    Palladium (II) complexes with 1-pheny1-3-methy1-4-(arylhydrazo)-5- pyrazolone dyes were studied spectrophotometrically. Pd (II) forms 1:1 and 1:2 complexes with the ligands by the replacement of their phenolic and hydrazo protons. The ligands behave as tridentate in the 1:1 complex and as bidentate in the 1:2 complex. The sability constants of these complexes are dependent on the type of substituents in the benzene ring of the arylazo moiety.

  14. 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. PMID:27040752

  15. Core percolation on complex networks.

    PubMed

    Liu, Yang-Yu; Csóka, Endre; Zhou, Haijun; Pósfai, Márton

    2012-11-16

    We analytically solve the core percolation problem for complex networks with arbitrary degree distributions. We find that purely scale-free networks have no core for any degree exponents. We show that for undirected networks if core percolation occurs then it is continuous while for directed networks it is discontinuous (and hybrid) if the in- and out-degree distributions differ. We also find that core percolations on undirected and directed networks have completely different critical exponents associated with their critical singularities. PMID:23215509

  16. Variation of Exciton-Vibrational Coupling in Photosystem II Core Complexes from Thermosynechococcus elongatus As Revealed by Single-Molecule Spectroscopy

    PubMed Central

    2015-01-01

    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. PMID:25708355

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

    PubMed Central

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

    2007-01-01

    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+(μ-O2−)Ca2+, for IM1*. We postulate an analogous inhibited intermediate with Cd2+ replacing Ca2+. PMID:17954439

  18. 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+. PMID:17954439

  19. 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. PMID:26567571

  20. Probing the coupling between proton and electron transfer in Photosystem II core complexes containing a 3-fluorotyrosine

    PubMed Central

    Rappaport, Fabrice; Boussac, Alain; Force, Dee Ann; Peloquin, Jeffrey; Brynda, Marcin; Sugiura, Miwa; Un, Sun; Britt, R. David; Diner, Bruce A.

    2009-01-01

    The catalytic cycle of numerous enzymes involves the coupling between proton transfer and electron transfer. Yet, the understanding of this coordinated transfer in biological systems remains limited, likely because its characterization relies on the controlled but experimentally challenging modifications of the free energy changes associated with either the electron or proton transfer. We have performed such a study here in Photosystem II. The driving force for electron transfer from TyrZ to P680•+ has been decreased by ~ 80 meV by mutating the axial ligand of P680, and that for proton transfer upon oxidation of TyrZ by substituting a 3-fluorotyrosine (3F-TyrZ) for TyrZ. In Mn-depleted Photosystem II, the dependence upon pH of the oxidation rates of TyrZ and 3F-TyrZ were found to be similar. However, in the pH range where the phenolic hydroxyl of TyrZ is involved in a H-bond with a proton acceptor, the activation energy of the oxidation of 3F-TyrZ is decreased by 110 meV, a value which correlates with the in vitro finding of a 90 meV stabilization energy to the phenolate form of 3F-Tyr when compared to Tyr (Seyedsayamdost et al., 2006, JACS 128:1569–79). Thus, when the phenol of YZ acts as a H-bond-donor, its oxidation by P680•+ is controlled by its prior deprotonation. This contrasts with the situation prevailing at lower pH, where the proton acceptor is protonated and therefore unavailable, in which the oxidation-induced proton transfer from the phenolic hydroxyl of TyrZ has been proposed to occur concertedly with the electron transfer to P680•+. This suggests a switch between a concerted proton/electron transfer at pHs < 7.5 to a sequential one at pHs > 7.5 and illustrates the roles of the H-bond and of the likely salt-bridge existing between the phenolate and the nearby proton acceptor in determining the coupling between proton and electron transfer. PMID:19265377

  1. Alpine Corsica Metamorphic Core Complex

    NASA Astrophysics Data System (ADS)

    Fournier, Marc; Jolivet, Laurent; Goffé, Bruno; Dubois, Roland

    1991-12-01

    Alpine Corsica is an example where superficial nonmetamorphic allochtonous units rest upon a highly strained metamorphic complex. Early ductile deformation under high pressure-low temperature (HP-LT) conditions is due to the westward thrusting of oceanic material onto a continental basement as shown by previous studies. New thermobarometric estimates yield minimal peak HP-LT metamorphism conditions of 11 kbar at 400°C. The early deformation is overprinted by a ductile deformation with an eastward sense of shear postdating or contemporaneous with mineral recrystallizations in the greenschist facies conditions. Early compressive thrust contacts are reworked as east dipping ductile normal faults and the less competent units display only eastward shear criteria. The upper units are affected by an extensional brittle deformation, and east dipping brittle normal faults bound to the west the early to middle Miocene Saint-Florent half-graben. The greenschist metamorphic event lasted until 33 Ma, which is contemporaneous with the beginning of the extension in the Liguro-Provençal basin. We interpret the second deformation stage as the result of a ductile extension following the overthickening of the crust due to the westward thrusting. Extension reduces the thickness of the crust so that upper units free from early P-T conditions are brought into close contact with a HP-LT metamorphic core complex. The geometry of the late extension is controlled by that of the early compressive thrust.

  2. Diversity of parasite complex II.

    PubMed

    Harada, Shigeharu; Inaoka, Daniel Ken; Ohmori, Junko; Kita, Kiyoshi

    2013-05-01

    Parasites have developed a variety of physiological functions necessary for completing at least part of their life cycles in the specialized environments of surrounding the parasites in the host. Regarding energy metabolism, which is essential for survival, parasites adapt to the low oxygen environment in mammalian hosts by using metabolic systems that are very different from those of the hosts. In many cases, the parasite employs aerobic metabolism during the free-living stage outside the host but undergoes major changes in developmental control and environmental adaptation to switch to anaerobic energy metabolism. Parasite mitochondria play diverse roles in their energy metabolism, and in recent studies of the parasitic nematode, Ascaris suum, the mitochondrial complex II plays an important role in anaerobic energy metabolism of parasites inhabiting hosts by acting as a quinol-fumarate reductase. In Trypanosomes, parasite complex II has been found to have a novel function and structure. Complex II of Trypanosoma cruzi is an unusual supramolecular complex with a heterodimeric iron-sulfur subunit and seven additional non-catalytic subunits. The enzyme shows reduced binding affinities for both substrates and inhibitors. Interestingly, this structural organization is conserved in all trypanosomatids. Since the properties of complex II differ across a wide range of parasites, this complex is a potential target for the development of new chemotherapeutic agents. In this regard, structural information on the target enzyme is essential for the molecular design of drugs. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease. PMID:23333273

  3. Core organization of directed complex networks

    NASA Astrophysics Data System (ADS)

    Azimi-Tafreshi, N.; Dorogovtsev, S. N.; Mendes, J. F. F.

    2013-03-01

    The recursive removal of leaves (dead end vertices) and their neighbors from an undirected network results, when this pruning algorithm stops, in a so-called core of the network. This specific subgraph should be distinguished from k-cores, which are principally different subgraphs in networks. If the vertex mean degree of a network is sufficiently large, the core is a giant cluster containing a finite fraction of vertices. We find that generalization of this pruning algorithm to directed networks provides a significantly more complex picture of cores. By implementing a rate equation approach to this pruning procedure for directed uncorrelated networks, we identify a set of cores progressively embedded into each other in a network and describe their birth points and structure.

  4. Characterization of synthetic oxomanganese complexes and the inorganic core of the O2-evolving complex in photosystem II: evaluation of the DFT/B3LYP level of theory.

    PubMed

    Sproviero, Eduardo M; Gascon, Jose A; McEvoy, James P; Brudvig, Gary W; Batista, Victor S

    2006-04-01

    The capabilities and limitations of the Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional are investigated as applied to studies of mixed-valent multinuclear oxomanganese complexes. Benchmark calculations involve the analysis of structural, electronic and magnetic properties of di-, tri- and tetra-nuclear Mn complexes, previously characterized both chemically and spectroscopically, including the di-mu-oxo bridged dimers [Mn(III)Mn(IV)(mu-O)(2)(H(2)O)(2)(terpy)(2)](3+) (terpy=2,2':6,2''-terpyridine) and [Mn(III)Mn(IV)(mu-O)(2)(phen)(4)](3+) (phen=1,10-phenanthroline), the Mn trimer [Mn(3)O(4)(bpy)(4)(H(2)O)(2)](4+) (bpy=2,2'-bipyridine), and the tetramer [Mn(4)O(4)L(6)](+) with L=Ph(2)PO(2)(-). Furthermore, the density functional theory (DFT) B3LYP level is applied to analyze the hydrated Mn(3)O(4)CaMn cluster completely ligated by water, OH(-), Cl(-), carboxylate and imidazole ligands, analogous to the '3+1 Mn tetramer' of the oxygen-evolving complex of photosystem II. It is found that DFT/B3LYP predicts structural and electronic properties of oxomanganese complexes in pre-selected spin-electronic states in very good agreement with X-ray and magnetic experimental data, even when applied in conjunction with rather modest basis sets. However, it is conjectured that the energetics of low-lying spin-states is beyond the capabilities of the DFT/B3LYP level, constituting a limitation to mechanistic studies of multinuclear oxomanganese complexes where until now the performance of DFT/B3LYP has raised little concern. PMID:16510187

  5. 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 PAGESBeta

    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 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

  6. Oceanic Core Complexes on the Mohns Ridge

    NASA Astrophysics Data System (ADS)

    Denny, A. R.; Pedersen, R. B.

    2013-12-01

    The Mohns Ridge, an ultra-slow spreading ridge in the Arctic Mid-Ocean Ridge system, is host to multiple volcanic and tectonic spreading segments. This oblique-spreading ridge is hotspot influenced at its southern terminus and is bound to the north by a curvilinear contact with the highly oblique Knipovich Ridge. This study examines EM120 multibeam bathymetry of the Mohns Ridge collected from 1999-2001 and gridded to 50 m cell size. Geomorphic interpretation of near-axis and off-axis structures reveals multiple expressions of potential oceanic core complexes (OCCs) along the 550 km long spreading axis. The OCCs form only on the western side of the spreading axis, consistent with the increased tectonic vs. volcanic morphology of the western flank of the Mohns Ridge. In the southern Mohns Ridge OCCs occur adjacent to on-axis active volcanic spreading centers. In the northern Mohns Ridge OCCs appear related to both ';V' shaped northern-propagating ridge spreading centers and spreading-parallel strings of core complexes extending at least 60 km off axis in the direction of spreading. This geomorphic interpretation should be further refined by dedicated ship-based investigations to fully describe this unique oblique-spreading Arctic Ridge system.

  7. 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.

  8. 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.

  9. 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

  10. Origin of metamorphic core complexes and detachment faults

    NASA Astrophysics Data System (ADS)

    Wu, G.; Lavier, L. L.

    2013-12-01

    Origin of metamorphic core complexes and detachment faults Guangliang Wu1,2, Luc L. Lavier1,2 1 Institute for Geophysics, University of Texas at Austin, TX 78758, USA 2 Department of Geological Sciences, University of Texas at Austin, TX 78712, USA Metamorphic core complexes (MCCs) and detachment faults are widely observed in collapsing orogens, such as Western US Cordillera, the Aegean and Papua New Guinea. A theory for the origin of MCCs has to provide: i) a viable mechanism to bring deeper crustal material to the surface, ii) a scenario that allows slip on low-angle detachment faults, and iii) a viable mechanism to form a flat Moho at a certain stage of evolution. However, previous models ignored at least one of these three requirements. Using thermo-mechanical models constrained by geological and geophysical observation, we simulated MCCs and detachment faults in the context of collapsing orogens with preexisting shear zones and middle crust of variable strength. We found that MCCs and detachment faults are natural products of gravity driven middle crustal extrusion and exhumation and strong crustal decoupling along the preexisting shear zones in a favorable state of stress in collapsing orogens. Based on previous geological and geophysical observations and our numerical simulations, we categorized MCCs into four types: i) massifs, such as Menderes massif and SW Rhodope massif, ii) single large asymmetric MCC (classic MCC), such as Whipple mountains and Snake Range Mountains, Western US Cordillera and Crete and Cyclades, the Aegean, iii) multiple less evolved MCCs, such as Black Mountains turtlebacks, and iv) subsurface ';MCC', such as interpreted at the Adriatic coast. We also recognized two types of detachment faults: one being listric fault transitioning to a convex upward shear zone at greater depth and the other a shallow exhumed upward convex shear zone. Our new models successfully predict many MCCs and detachment faults known to date.

  11. Three new polynuclear copper(II) complexes with the symmetric [Cu(mu1,1-N3)2Cu]2+ core and pyridine derivatives: syntheses, structure, and magnetic behavior.

    PubMed

    Escuer, A; Goher, M A; Mautner, F A; Vicente, R

    2000-05-15

    Three new polynuclear copper(II) complexes, derived from the end-on azido bridging ligand and pyridine derivatives, have been synthesized, and their crystal structures have been determined by X-ray diffraction methods; they are the dinuclear compounds [Cu2(mu 1,1-N3)2(4-Etpy)4(mu-NO3)2] (1), and [Cu2(mu 1,1-N3)2(3-ampy)4(mu-NO3)2]. C2H5OH (2), and the trinuclear [Cu3(mu 1,1-N3)4(N3)2(Meinic)2(DMF)2] (3). 4-Etpy is 4-ethylpyridine, 3-ampy is 3-aminopyridine, and Meinic is methylisonicotinate. Compound 1, C28H36Cu2N12O6, crystallized in the monoclinic system, space group P2(1)/n, with a = 12.355(9) A, b = 12.474(4) A, c = 12.854(6) A, beta = 117.68(4) degrees, and Z = 2. Compound 2, C22H30Cu2N16O7, crystallized in the triclinic system, space group P1, with a = 9.695(2) A, b = 10.895(2) A, c = 7.909(2) A, alpha = 96.81(3) degrees, beta = 96.40(3) degrees, gamma = 96.56(3) degrees and Z = 1. Compound 3, C20H28-Cu3N22O6, crystallized in the monoclinic system, space group P2(1)/n, with a = 7.755(2) A, b = 14.680(5) A, c = 15.810(5) A, beta = 102.81(2) degrees, and Z = 2. 1-3 have the symmetric [Cu(mu 1,1-N3)2Cu]2+ core and structural parameters outside the previously reported range. Magnetic susceptibility data, measured from 2 to 300 K, show strong ferromagnetic coupling for the dinuclear end-on compounds 1 and 2 and bulk moderate ferromagnetic coupling for the trinuclear compound 3. These data were fitted to the appropriate equations derived from the Hamiltonian H = -JS1S2 for 1 and 2 and from the Hamiltonian H = -J1(SA1SB + SA2SB) - J2SA1.SA2 for 3, giving the parameters J = 230.1(1) cm-1, g = 2.17(0.01) for 1, J = 223.2(2) cm-1, g = 2.16(0.01) for 2, and J1 = 47.3(2) cm-1, J2 = -22.5(1) cm-1, gA = 2.26(0.02), gB = 2.07(0.03) for 3. The magnetic susceptibility data can be correlated with the structural parameters. PMID:12526520

  12. Architecture and function of plant light-harvesting complexes II.

    PubMed

    Pan, Xiaowei; Liu, Zhenfeng; Li, Mei; Chang, Wenrui

    2013-08-01

    The antenna system associated with plant photosystem II (PSII) comprises a series of light-harvesting complexes II (LHCIIs) which are supramolecular assemblies of chlorophylls, carotenoids, lipids and integral membrane proteins. These complexes not only function in capturing and transmitting light energy, but also have pivotal roles in photoprotection under high-light conditions through a mechanism known as non-photochemical quenching process. Among them, the most abundant major species (majLHCII) is located at the periphery of PSII and forms homo/hetero-trimers. Besides, three minor species, named CP29, CP26 and CP24, are adjacent to the PSII core, exist in monomeric form and bridge the majLHCII trimers with the core complex. Structural studies on majLHCII and CP29 have revealed the overall architecture of plant LHC family, the binding sites of pigment molecules and the distribution pattern of chromophores in three-dimensional space. The high-resolution structural data of LHCIIs serve as fundamental bases for an improved understanding on the mechanisms of light harvesting, energy transfer and photoprotection processes in plants. PMID:23623335

  13. Connecting core percolation and controllability of complex networks.

    PubMed

    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

  14. Characterization and biological studies on Co(II), Ni(II) and Cu(II) complexes of carbohydrazones ending by pyridyl ring

    NASA Astrophysics Data System (ADS)

    Abu El-Reash, G. M.; El-Gammal, O. A.; Ghazy, S. E.; Radwan, A. H.

    2013-03-01

    The chelating behavior of ligands based on carbohydrazone core modified with pyridine end towards Co(II), Ni(II) and Cu(II) ions have been examined. The ligands derived from the condensation of carbohydrazide with 2-acetylpyridine (H2APC) and 4-acetylpyridine (H2APEC). The 1H NMR, IR data and the binding energy calculations of H2APC revealed the presence of two stereoisomers syn and anti in the solid state and in the solution. The 1H NMR, IR data and the binding energy calculations confirmed the presence of H2APEC in one keto form only in the solid state and in the solution. The spectroscopic data confirmed that H2APC behaves as a monobasic pentadentate in Co(II) and Cu(II) complexes and as mononegative tetradentate in Ni(II) complex. On the other hand, H2APEC acts as a mononegative tridentate in Co(II) complex, neutral tridentate in Ni(II) complex and neutral bidentate in Cu(II) complex. The electronic spectra and the magnetic measurements of complexes as well as the ESR of the copper complexes suggested the octahedral geometry. The bond length and bond angles were evaluated by DFT method using material studio program. The thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. The antioxidant (DDPH and ABTS methods), anti-hemolytic and in vitro Ehrlich ascites of the compounds have been screened.

  15. XAFS study of Ni (II) aminovinylketone complexes

    NASA Astrophysics Data System (ADS)

    Yalovega, Galina E.; Vlasenko, Valerii G.; Uraev, Ali I.; Garnovskii, Alexander D.; Soldatov, Alexander V.

    2006-11-01

    The functional properties of the active sites in a metalloproteins depend on coordination geometry of metal, the number and the nature of coordination ligands. The Ni K-edge XAFS spectra of novel nickel complexes as models for the MeN 2O 2(S 2) active site in metalloproteins were measured and analyzed. Theoretical analysis of the Ni K-edge XANES was performed using FDMNES code based on the finite difference method (FDM) to solve the Schrödinger equation beyond muffin-tin approximations and self-consistent full multiple-scattering approach (code FEFF8.2). It was found that the spectrum is almost totally formed by the octahedron of the nearest neighbor atoms around Ni ion in the II (Ni) complex. The III (Ni) complex active center exists in square-planar configuration with shorter distances.

  16. Cadmium(II) complex formation with glutathione.

    PubMed

    Mah, Vicky; Jalilehvand, Farideh

    2010-03-01

    Complex formation between heavy metal ions and glutathione (GSH) is considered as the initial step in many detoxification processes in living organisms. In this study the structure and coordination between the cadmium(II) ion and GSH were investigated in aqueous solutions (pH 7.5 and 11.0) and in the solid state, using a combination of spectroscopic techniques. The similarity of the Cd K-edge and L(3)-edge X-ray absorption spectra of the solid compound [Cd(GS)(GSH)]ClO(4).3H(2)O, precipitating at pH 3.0, with the previously studied cysteine compound {Cd(HCys)(2).H(2)O}(2).H(3)O(+).ClO(4) (-) corresponds to Cd(S-GS)(3)O (dominating) and Cd(S-GS)(4) four-coordination within oligomeric complexes with mean bond distances of 2.51 +/- 0.02 A for Cd-S and 2.24 +/- 0.04 A for Cd-O. For cadmium(II) solutions (C (Cd(II)) approximately 0.05 M) at pH 7.5 with moderate excess of GSH (C (GSH)/C (Cd(II)) = 3.0-5.0), a mix of Cd(S-GS)(3)O (dominating) and Cd(S-GS)(4) species is consistent with the broad (113)Cd NMR resonances in the range 632-658 ppm. In alkaline solutions (pH 11.0 and C (GSH)/C (Cd(II)) = 2.0 or 3.0), two distinct peaks at 322 and 674 ppm are obtained. The first peak indicates six-coordinated mononuclear and dinuclear complexes with CdS(2)N(2)(N/O)(2) and CdSN(3)O(2) coordination in fast exchange, whereas the second corresponds to Cd(S-GS)(4) sites. At high ligand excess the tetrathiolate complex, Cd(S-GS)(4), characterized by a sharp delta((113)Cd) NMR signal at 677 ppm, predominates. The average Cd-S distance, obtained from the X-ray absorption spectra, varied within a narrow range, 2.49-2.53 A, for all solutions (pH 7.5 and 11.0) regardless of the coordination geometry. PMID:20035360

  17. Lead(II) complex formation with glutathione.

    PubMed

    Mah, Vicky; Jalilehvand, Farideh

    2012-06-01

    A structural investigation of complexes formed between the Pb(2+) ion and glutathione (GSH, denoted AH(3) in its triprotonated form), the most abundant nonprotein thiol in biological systems, was carried out for a series of aqueous solutions at pH 8.5 and C(Pb(2+)) = 10 mM and in the solid state. The Pb L(III)-edge extended X-ray absorption fine structure (EXAFS) oscillation for a solid compound with the empirical formula [Pb(AH(2))]ClO(4) was modeled with one Pb-S and two short Pb-O bond distances at 2.64 ± 0.04 and 2.28 ± 0.04 Å, respectively. In addition, Pb···Pb interactions at 4.15 ± 0.05 Å indicate dimeric species in a network where the thiolate group forms an asymmetrical bridge between two Pb(2+) ions. In aqueous solution at the mole ratio GSH/Pb(II) = 2.0 (C(Pb(2+)) = 10 mM, pH 8.5), lead(II) complexes with two thiolate ligands form, characterized by a ligand-to-metal charge-transfer band (LMCT) S(-) → Pb(2+) at 317 nm in the UV-vis spectrum and mean Pb-S and Pb-(N/O) bond distances of 2.65 ± 0.04 and 2.51 ± 0.04 Å, respectively, from a Pb L(III)-edge EXAFS spectrum. For solutions with higher mole ratios, GSH/Pb(II) ≥ 3.0, electrospray ionization mass spectroscopy spectra identified a triglutathionyllead(II) complex, for which Pb L(III)-edge EXAFS spectroscopy shows a mean Pb-S distance of 2.65 ± 0.04 Å in PbS(3) coordination, (207)Pb NMR spectroscopy displays a chemical shift of 2793 ppm, and in the UV-vis spectrum, an S(-) → Pb(2+) LMCT band appears at 335 nm. The complex persists at high excess of GSH and also at ∼25 K in frozen glycerol (33%)/water glasses for GSH/Pb(II) mole ratios from 4.0 to 10 (C(Pb(2+)) = 10 mM) measured by Pb L(III)-edge EXAFS spectroscopy. PMID:22594853

  18. Out-of-Core Solutions of Complex Sparse Linear Equations

    NASA Technical Reports Server (NTRS)

    Yip, E. L.

    1982-01-01

    ETCLIB is library of subroutines for obtaining out-of-core solutions of complex sparse linear equations. Routines apply to dense and sparse matrices too large to be stored in core. Useful for solving any set of linear equations, but particularly useful in cases where coefficient matrix has no special properties that guarantee convergence with any of interative processes. The only assumption made is that coefficient matrix is not singular.

  19. 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.

  20. 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

  1. 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.

  2. Structural diversity in dinickel(II) complexes of thiosemicarbazones

    NASA Astrophysics Data System (ADS)

    Naik, Anil D.; Annigeri, Satish M.; Gangadharmath, Umesh B.; Revankar, Vidyanand K.; Mahale, Vinayak B.

    2002-10-01

    2,6-Diformyl- p-cresol serves as a starting point for the generation of multidentate N/O/S chelating agents. Condensation with 4-(X-phenyl) thiosemicarbazide yields the pentadentate ligand having SNONS donor sequences, capable of holding two metal ions in close proximity. The ligands behave as mono/di/tri basic depending on the pH of the medium. Stereochemical diversity in the reaction product of such ligands with nickel(II) chloride at different pH is observed. Sterically demanding substituted ligands in association with various exogenous bridges dictate the geometry and coordination number of such complexes. The compounds were investigated by elemental analysis, molar conductivities, electronic spectra, IR, NMR, FAB mass spectra, TG-DTG, magnetic susceptibility measurements. Varieties of geometries such as square planar, square pyramidal, octahedral and square planar-square pyramidal are observed. Cryomagnetic data for the complexes (79-296 K) can be reproduced by an equation based on the Heisenberg model ( H=-2 JS1S2, S1= S2=1). The singlet-triplet splitting, J varies systematically with the coordination geometry about the Ni 2(SNONS) core, with the hydroxo bridged complex exhibiting the greatest degree of antiferromagnetic coupling. The coupling is somewhat weaker for the chloro-bridged complexes. None of the complexes have shown any appreciable antimicrobial activity.

  3. 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.

  4. Basal core promoters control the equilibrium between negative cofactor 2 and preinitiation complexes in human cells

    PubMed Central

    2010-01-01

    Background The general transcription factor TFIIB and its antagonist negative cofactor 2 (NC2) are hallmarks of RNA polymerase II (RNAPII) transcription. Both factors bind TATA box-binding protein (TBP) at promoters in a mutually exclusive manner. Dissociation of NC2 is thought to be followed by TFIIB association and subsequent preinitiation complex formation. TFIIB dissociates upon RNAPII promoter clearance, thereby providing a specific measure for steady-state preinitiation complex levels. As yet, genome-scale promoter mapping of human TFIIB has not been reported. It thus remains elusive how human core promoters contribute to preinitiation complex formation in vivo. Results We compare target genes of TFIIB and NC2 in human B cells and analyze associated core promoter architectures. TFIIB occupancy is positively correlated with gene expression, with the vast majority of promoters being GC-rich and lacking defined core promoter elements. TATA elements, but not the previously in vitro defined TFIIB recognition elements, are enriched in some 4 to 5% of the genes. NC2 binds to a highly related target gene set. Nonetheless, subpopulations show strong variations in factor ratios: whereas high TFIIB/NC2 ratios select for promoters with focused start sites and conserved core elements, high NC2/TFIIB ratios correlate to multiple start-site promoters lacking defined core elements. Conclusions TFIIB and NC2 are global players that occupy active genes. Preinitiation complex formation is independent of core elements at the majority of genes. TATA and TATA-like elements dictate TFIIB occupancy at a subset of genes. Biochemical data support a model in which preinitiation complex but not TBP-NC2 complex formation is regulated. PMID:20230619

  5. 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.

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

    PubMed

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

    2015-08-24

    To overcome the bottleneck of water splitting, the exploration of efficient, selective, and stable water oxidation catalysts (WOCs) is crucial. We report an all-inorganic, oxidatively and hydrolytically stable WOC based on a polyoxometalate [(A-α-SiW9 O34)2Co8(OH)6(H2O)2(CO3)3](16-) (Co8 POM). As a cobalt(II)-based cubane water oxidation catalyst, Co8POM embeds double Co(II)4O3 cores. The self-assembled catalyst is similar to the oxygen evolving complex (OEC) of photosystem II (PS II). Using [Ru(bpy)3](2+) as a photosensitizer and persulfate as a sacrificial electron acceptor, Co8POM exhibits excellent water oxidation activity with a turnover number (TON) of 1436, currently the highest among bioinspired catalysts with a cubical core, and a high initial turnover frequency (TOF). Investigation by several spectroscopy, spectrometry, and other techniques confirm that Co8POM is a stable and efficient catalyst for visible light-driven water oxidation. The results offer a useful insight into the design of water oxidation catalysts. PMID:26130568

  7. New macrocyclic schiff base complexes incorporating a homopiperazine unit: Synthesis of some Co(II), Ni(II),Cu(II) and Zn(II) complexes and crystal structure and theoretical studies

    NASA Astrophysics Data System (ADS)

    Keypour, Hassan; Rezaeivala, Majid; Ramezani-Aktij, Ameneh; Bayat, Mehdi; Dilek, Nefise; Ünver, Hüseyin

    2016-07-01

    A new macrocyclic Schiff base ligand, L, was synthesized by condensation reaction of 1,4-bis(2-formylphenyl)homopiperazine and 1,4-diaminobutane in acetonitrile. The Schiff base ligand was characterized by using elemental analyses, FT-IR, 1H, 13C NMR and mass spectroscopic techniques. The metal (II) complexes [ML], were synthesized from the reaction of MCl2.nH2O (M: Co, Ni, Cu and Zn) with Schiff base ligand, L and characterized by elemental analyses and FT-IR. X-ray crystal structure of [CoLCl]+ distorted square pyramidal geometry with an N4Cl core, arising from coordination by the four donor nitrogen atoms from the macrocyclic framework and one Cl atom. It crystallizes triclinic space group, P-1 with a = 7.1777(1) Å, b = 11.0357 (2) Å, c = 15.1520(2) Å, V = 1183.14(3), Z = 2, Dc = 1.556 g cm-3, μ (MoKα) = 0.156 mm-1. Also, the bonding situation between the [MCl]+ and Ligand (L) fragments in [MLCl]ClO4 (M = Co(II), Ni(II), Cu(II), Zn(II)) complexes were carried out by energy-decomposition analysis (EDA). The results showed that there is an increasing trend in the case of ΔEelstat of the complexes by changing the M from Co(II) to Zn(II).

  8. Probing bistability in Fe(II) and Co(II) complexes with an unsymmetrically substituted quinonoid ligand.

    PubMed

    van der Meer, Margarethe; Rechkemmer, Yvonne; Breitgoff, Frauke D; Dechert, Sebastian; Marx, Raphael; Dörfel, María; Neugebauer, Petr; van Slageren, Joris; Sarkar, Biprajit

    2016-05-28

    The generation of molecular platforms, the properties of which can be influenced by a variety of external perturbations, is an important goal in the field of functional molecular materials. We present here the synthesis of a new quinonoid ligand platform containing an [O,O,O,N] donor set. The ligand is derived from a chloranilic acid core by using the [NR] (nitrogen atom with a substituent R) for [O] isoelectronic substitution. Mononuclear Fe(II) and Co(II) complexes have been synthesized with this new ligand. Results obtained from single crystal X-ray crystallography, NMR spectroscopy, (spectro)electrochemistry, SQUID magnetometry, multi-frequency EPR spectroscopy and FIR spectroscopy are used to elucidate the electronic and geometric structures of the complexes. Furthermore, we show here that the spin state of the Fe(II) complex can be influenced by temperature, pressure and light and the Co(II) complex displays redox-induced spin-state switching. Bistability is observed in the solid-state as well as in solution for the Fe(II) complex. The new ligand presented here, owing to the [NR] group present in it, will likely have more adaptability while investigating switching phenomena compared to its [O,O,O,O] analogues. Thus, such classes of ligands as well as the results obtained on the reversible changes in physical properties of the metal complexes are likely to contribute to the generation of multifunctional molecular materials. PMID:27109712

  9. 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.

  10. Assembly and solution structure of the core retromer protein complex.

    PubMed

    Norwood, Suzanne J; Shaw, Daniel J; Cowieson, Nathan P; Owen, David J; Teasdale, Rohan D; Collins, Brett M

    2011-01-01

    Retromer is a peripheral membrane protein complex that has pleiotropic roles in endosomal membrane trafficking. The core of retromer possesses three subunits, VPS35, VPS29 and VPS26, that play different roles in binding to cargo, regulatory proteins and complex stabilization. We have performed an investigation of the thermodynamics of core retromer assembly using isothermal titration calorimetry (ITC) demonstrating that VPS35 acts as the central subunit to which VPS29 and VPS26 bind independently. Furthermore, we confirm that the conserved PRLYL motif of the large VPS35 subunit is critical for direct VPS26 interaction. Heat capacity measurements of VPS29 and VPS26 binding to VPS35 indicate extensive binding interfaces and suggest conformational alterations in VPS29 or VPS35 upon complex formation. Solution studies of the retromer core using small-angle X-ray scattering allow us to propose a model whereby VPS35 forms an extended platform with VPS29 and VPS26 bound at distal ends, with the potential for forming dimeric assemblies. PMID:20875039

  11. Synthesis, magnetism and spectral studies of six defective dicubane tetranuclear {M4O6} (M = Ni(II), Co(II), Zn(II)) and three trinuclear Cd(II) complexes with polydentate Schiff base ligands.

    PubMed

    Jiang, Lin; Zhang, Dong-Yan; Suo, Jing-Jing; Gu, Wen; Tian, Jin-Lei; Liu, Xin; Yan, Shi-Ping

    2016-06-21

    A series of Ni(II), Co(II), Zn(II) and Cd(II) complexes with polytopic Schiff base ligands have been synthesized. The single-crystal X-ray crystallography results show that tetranuclear complexes have common face-shared defective dicubane cores, whereas trinuclear Cd(II) complexes are almost linear entities. Synthesis methods (solvent evaporation and hydrothermal synthesis), reaction conditions (pH, solvents and dosage) and coligands (azide, methanol, chloride and acetate) play vital roles in determining the final structure of the complexes and therefore their magnetic properties. In complexes , the terminal and central M(2+) ions are connected through mixed bridges, μ-phenoxido/μ1,1,1-X and μ-Oalphatic/μ1,1,1-X, while central two M(2+) ions are linked by double bridges, μ1,1,1-X (X = azido and methoxido groups for and respectively). For complex , two central Ni(II) ions are connected through two μ1,1,1-N3(-) which is relatively less reported. For complexes , there are two kinds of Cd(II), the centre Cd(II) ions are eight-coordinated with triangle dodecahedral geometries, while the two side Cd(II) ions are six-coordinated with trigonal prism geometries using chlorides or acetates as terminal ligands. Magnetic susceptibility measurements (χM) for compounds have been performed, and they reveal predominant ferromagnetic exchange interactions in Co(II) and Ni(II) tetramers. The photoluminescence studies show that the Zn(II) complex and three Cd(II) complexes have strong fluorescence, and the lifetimes are measured to be in the 10(2) nanosecond timescale. PMID:27230103

  12. The Common Core State Standards' Quantitative Text Complexity Trajectory: Figuring out How Much Complexity Is Enough

    ERIC Educational Resources Information Center

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

    2013-01-01

    The Common Core State Standards (CCSS) set a controversial aspirational, quantitative trajectory for text complexity exposure for readers throughout the grades, aiming for all high school graduates to be able to independently read complex college and workplace texts. However, the trajectory standard is presented without reference to how the…

  13. New N^C^N-coordinated Pd(ii) and Pt(ii) complexes of a tridentate N-heterocyclic carbene ligand featuring a 6-membered central ring: synthesis, structures and luminescence.

    PubMed

    Moussa, Jamal; Haddouche, Kamel; Chamoreau, Lise-Marie; Amouri, Hani; Gareth Williams, J A

    2016-08-01

    We describe Pd(ii) and Pt(ii) complexes of an N^C^N-coordinating pincer-like ligand featuring two lateral pyridine rings and a 6-membered carbene core. Their crystal structures display 1-dimensional chains with short π-π and M(ii)M(ii) interactions. Such interactions also impact on the photophysical properties, with the Pt(ii) complex being luminescent in the solid state at room temperature. PMID:27465432

  14. Photoassembly of the Water-Oxidizing Complex in Photosystem II

    PubMed Central

    Dasgupta, Jyotishman; Ananyev, Gennady M; Dismukes, G. Charles

    2008-01-01

    The light-driven steps in the biogenesis and repair of the inorganic core comprising the O2-evolving center of oxygenic photosynthesis (photosystem II water-oxidation complex, PSII-WOC) are reviewed. These steps, known collectively as photoactivation, involve the photoassembly of the free inorganic cofactors to the cofactor-depleted PSII-(apo-WOC) driven by light and produce the active O2-evolving core comprised of Mn4CaOxCly. We focus on the functional role of the inorganic components as seen through the competition with non-native cofactors (“inorganic mutants”) on water oxidation activity, the rate of the photoassembly reaction, and on structural insights gained from EPR spectroscopy of trapped intermediates formed in the initial steps of the assembly reaction. A chemical mechanism for the initial steps in photoactivation is given that is based on these data. Photoactivation experiments offer the powerful insights gained from replacement of the native cofactors, which together with the recent X-ray structural data for the resting holoenzyme provide a deeper understanding of the chemistry of water oxidation. We also review some new directions in research that photoactivation studies have inspired that look at the evolutionary history of this remarkable catalyst. PMID:19190725

  15. 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.

  16. The Origin of Complex Organic Molecules in Prestellar Cores

    NASA Astrophysics Data System (ADS)

    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 × 10-11 to 6 × 10-9. 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 H_2 ~2 × 104 cm-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.

  17. 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.

  18. Complex seismic anisotropy in the Earth's inner core beneath Africa

    NASA Astrophysics Data System (ADS)

    Yu, W.; Wen, L.

    2006-05-01

    Seismic anisotropy in the top of the inner core is important to the understanding of the growth and dynamics of the Earth's inner core. The anisotropic structures beneath Africa in the top 80 km of the inner core were not well constrained, due to limited sampling coverage. Here, we analyze a large data-set of the PKiKP-PKIKP phases sampling the top 80 km of the inner core beneath Africa along various sampling directions. The differential travel times of the PKiKP-PKIKP phases sampling Africa reveal polar-equatorial differences. The differential travel times along polar paths are about 0-1.4 s larger than those along equatorial paths, suggesting the presence of anisotropy in velocity in the top 80 km of the inner core beneath Africa. The PKiKP-PKIKP phases along polar paths exhibit a complex lateral gradient from the East to the Middle Africa and a correlation of large (small) differential travel time with small (large) amplitude ratio. Largest differential travel times and smallest amplitude ratios are observed beneath the East Africa (Kenya, Tanzania, Mozambique), while small differential travel times and large amplitude ratios are observed beneath the Middle Africa (Democratic Republic of Congo, Congo, Gabon, Angola). The polar PKiKP-PKIKP waveforms are grouped based on the geographic sampling regions. We perform waveform modeling and iteratively search for the anisotropic velocity and attenuation models that explain the polar PKiKP-PKIKP waveforms in various groups. Most complexities observed in the PKiKP-PKIKP waveforms can be explained by the presence of uniform anisotropy, but with onset of the anisotropy occurring at various depths. The region beneath the East Africa can be explained by a uniform anisotropy model with a magnitude of about 1.7% and an average Q value of 250 present at the inner core boundary (ICB), while the region beneath the Middle Africa can be explained by a model with an isotropic layer in the top and a uniform anisotropy with a

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

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Kumar, Umendra

    2005-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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(NO 3) 2 and Ni(L) 2(NO 3) 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(NO 3) 2 and Ni(L) 2(NO 3) 2 which are of tetrahedral geometry. A tetragonal geometry may be suggested for Cu(II) complexes.

  1. 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.

  2. Regulation of major histocompatibility complex class II genes

    PubMed Central

    Choi, Nancy M.; Majumder, Parimal; Boss, Jeremy M.

    2010-01-01

    Summary The major histocompatibility complex class II (MHC-II) genes are regulated at the level of transcription. Recent studies have shown that chromatin modification is critical for efficient transcription of these genes, and a number of chromatin modifying complexes recruited to MHC-II genes have been described. The MHC-II genes are segregated from each other by a series of chromatin elements, termed MHC-II insulators. Interactions between MHC-insulators and the promoters of MHC-II genes are mediated by the insulator factor CCCTC-binding protein and are critical for efficient expression. This regulatory mechanism provides a novel view of how the entire MHC-II locus is assembled architecturally and can be coordinately controlled. PMID:20970972

  3. Synthesis and characterization of iron(II) quinaldate complexes.

    PubMed

    Houghton, Dylan T; Gydesen, Nicholas W; Arulsamy, Navamoney; Mehn, Mark P

    2010-02-01

    Treatment of iron(II) chloride or iron(II) bromide with 2 equiv of sodium quinaldate (qn = quinaldate or C(10)H(6)NO(2)(-)) yields the coordinatively unsaturated mononuclear iron(II) quinaldate complexes Na[Fe(II)(qn)(2)Cl].DMF and Na[Fe(II)(qn)(2)Br].DMF (DMF = N,N-dimethylformamide), respectively. When a similar synthesis is carried out using iron(II) triflate, a solvent-derived linear triiron(II) complex, [Fe(II)(3)(qn)(6)(DMF)(2)], with two five-coordinate iron(II) centers and a single six-coordinate iron(II) center is obtained. Each of these species has been characterized using X-ray diffraction. The vibrational features of these complexes are consistent with the observed solid-state structures. Each of these compounds exhibits an iron(II)-to-quinaldate (pi*) charge-transfer band between 520 and 550 nm. These metal-to-ligand charge-transfer bands are sensitive to substitution of the quinaldates as well as alteration of the first coordination sphere ligands. However, the (1)H NMR spectra of these paramagnetic high-spin iron(II) complexes are not consistent with retention of the solid-state structures in a DMF solution. The chemical shifts, longitudinal relaxation times (T(1)), relative integrations, and substitution of the quinaldate ligands provide a means to fully assign the (1)H NMR spectra of the paramagnetic materials. These spectra are consistent with coordination equilibria between five- and six-coordinate species in a DMF solution. Electrochemical studies are reported to place these oxygen-sensitive compounds in a broader context with other iron(II) compounds. Iron complexes of bidentate quinoline-2-carboxylate-derived ligands are germane to metabolic pathways, environmental remediation, and catalytic applications. PMID:20030376

  4. Uniting Ruthenium(II) and Platinum(II) Polypyridine Centers in Heteropolymetallic Complexes Giving Strong Two-Photon Absorption.

    PubMed

    Shi, Pengfei; Coe, Benjamin J; Sánchez, Sergio; Wang, Daqi; Tian, Yupeng; Nyk, Marcin; Samoc, Marek

    2015-12-01

    New trinuclear RuPt2 and heptanuclear RuPt6 complex salts are prepared by attaching Pt(II) 2,2':6',2"-terpyridine (tpy) moieties to Ru(II) 4,4':2',2":4",4"'-quaterpyridine (qpy) complexes. Characterization includes single crystal X-ray structures for both polymetallic species. The visible absorption bands are primarily due to Ru(II) → qpy metal-to-ligand charge-transfer (MLCT) transitions, according to time-dependent density functional theory (TD-DFT) calculations. These spectra change only slightly on Pt coordination, while the orange-red emission from the complexes shows corresponding small red-shifts, accompanied by decreases in intensity. Cubic molecular nonlinear optical behavior has been assessed by using Z-scan measurements. These reveal relatively high two-photon absorption (2PA) cross sections σ2, with maximal values of 301 GM at 834 nm (RuPt2) and 523 GM at 850 nm (RuPt6) when dissolved in methanol or acetone, respectively. Attaching Pt(II)(tpy) moieties triples or quadruples the 2PA activities when compared with the Ru(II)-based cores. PMID:26562721

  5. The origin of detachment fault systems in core complexes

    SciTech Connect

    Scott, R.J.; Lister, G.S. . Dept. of Earth Sciences)

    1992-01-01

    At Planet Peak in the Buckskin Mountains, AZ, lower plate rocks are cut by numerous faults, the largest being moderate to gently, N to NE dipping normal faults with displacements from 10--100 meters. Superficially the structure of the lower plate appears similar to that of the upper plate, emphasizing the importance of brittle deformation in the evolution of the lower plate. This feature is inconsistent with recent models for core complexes in which the lower plate has low flexural strength. Mylonitic fabrics are best developed in the vicinity of Tertiary, mafic to intermediate intrusives. Where the intrusives are absent, lower plate rocks preserve the steeply dipping, NE-trending Proterozoic fabric. Typically the intrusives are far more intensely deformed than the adjacent wallrocks, indicating strain was localized within them. Local discordance between the mylonitic fabric in the intrusives and that in the wallrocks is the result of both intrusives cross-cutting earlier mylonitic fabrics and fault localization along intrusive contacts. The authors infer the association of mylonites and Tertiary intrusives to imply transient ductile deformation occurred in the thermal aureoles of shallow level intrusives, at less sand possibly much less than 10 km depth. Although thin igneous bodies implaced at shallow levels would be expected to cool extremely rapidly, the initial localization of strain may result in strain softening [+-] shear heating sufficient to enable further localized strain well after the initial heat input should have dissipated. Along the western Planet Peak, the Buckskin fault forms the upper contact to a thick suite of syn-extensional intrusives, lithologically similar to those of the Oligocene-Miocene lutonic complex that comprises 30% of the exposed lower plate in the Buckskin and Rawhide Mountains. They propose that core complex formation and detachment faulting are related to shallow level intrusion during Oligocene-Miocene extension of the region.

  6. Crystal structure of a transcription factor IIIB core interface ternary complex.

    PubMed

    Juo, Z Sean; Kassavetis, George A; Wang, Jimin; Geiduschek, E Peter; Sigler, Paul B

    2003-04-01

    Transcription factor IIIB (TFIIIB), consisting of the TATA-binding protein (TBP), TFIIB-related factor (Brf1) and Bdp1, is a central component in basal and regulated transcription by RNA polymerase III. TFIIIB recruits its polymerase to the promoter and subsequently has an essential role in the formation of the open initiation complex. The amino-terminal half of Brf1 shares a high degree of sequence similarity with the polymerase II general transcription factor TFIIB, but it is the carboxy-terminal half of Brf1 that contributes most of its binding affinity with TBP. The principal anchoring region is located between residues 435 and 545 of yeast Brf1, comprising its homology domain II. The same region also provides the primary interface for assembling Bdp1 into the TFIIIB complex. We report here a 2.95 A resolution crystal structure of the ternary complex containing Brf1 homology domain II, the conserved region of TBP and 19 base pairs of U6 promoter DNA. The structure reveals the core interface for assembly of TFIIIB and demonstrates how the loosely packed Brf1 domain achieves remarkable binding specificity with the convex and lateral surfaces of TBP. PMID:12660736

  7. Structural and Biochemical Insights into MLL1 Core Complex Assembly

    SciTech Connect

    Avdic, Vanja; Zhang, Pamela; Lanouette, Sylvain; Groulx, Adam; Tremblay, Véronique; Brunzelle, Joseph; Couture, Jean-François

    2012-05-02

    Histone H3 Lys-4 methylation is predominantly catalyzed by a family of methyltransferases whose enzymatic activity depends on their interaction with a three-subunit complex composed of WDR5, RbBP5, and Ash2L. Here, we report that a segment of 50 residues of RbBP5 bridges the Ash2L C-terminal domain to WDR5. The crystal structure of WDR5 in ternary complex with RbBP5 and MLL1 reveals that both proteins binds peptide-binding clefts located on opposite sides of WDR5s {beta}-propeller domain. RbBP5 engages in several hydrogen bonds and van der Waals contacts within a V-shaped cleft formed by the junction of two blades on WDR5. Mutational analyses of both the WDR5 V-shaped cleft and RbBP5 residues reveal that the interactions between RbBP5 and WDR5 are important for the stimulation of MLL1 methyltransferase activity. Overall, this study provides the structural basis underlying the formation of the WDR5-RbBP5 subcomplex and further highlight the crucial role of WDR5 in scaffolding the MLL1 core complex.

  8. Self-assembled dicopper(II) diethanolaminate cores for mild aerobic and peroxidative oxidation of alcohols.

    PubMed

    Figiel, Paweł J; Kirillov, Alexander M; Guedes da Silva, M Fátima C; Lasri, Jamal; Pombeiro, Armando J L

    2010-11-01

    The new dicopper(ii) complexes [Cu(2)(μ-Hmdea)(2)(NCS)(2)] (1) and [Cu(2)(μ-Hedea)(2)(N(3))(2)]·(H(2)O)(0.25) (2) with the {Cu(2)(μ-O)(2)} diethanolaminate cores have been easily generated by aqueous medium self-assembly reactions of copper(ii) nitrate with N-methyl- or N-ethyldiethanolamine (H(2)mdea or H(2)edea, respectively), in the presence of sodium thiocyanate (for 1) or sodium azide (for 2) as ancillary ligands sources. They have been isolated as air-stable crystalline solids and fully characterized by IR and UV-vis spectroscopies, ESI-MS(+), elemental and single-crystal X-ray diffraction analyses. The latter complex also features a fourfold linkage of neighbouring dimeric units via strong intermolecular O-HO hydrogen bonds, giving rise to the formation of tetracopper aggregates. The catalytic activity of compounds 1 and 2 has been studied for the mild (50-80 °C) and selective oxidations of alcohols, namely for (i) the aerobic aqueous medium oxidation of benzyl alcohols to benzaldehydes, mediated by TEMPO radical, and for (ii) the solvent-free oxidation of secondary alcohols to ketones by t-BuOOH under microwave (MW) irradiation. Complex 2 shows the highest efficiency in both oxidation systems, resulting in up to 99% molar yields (based on the alcohol substrate) of products. In addition, remarkably high values of TON (1020) and TOF (4080 h(-1)) have been achieved in the MW-assisted peroxidative oxidation of 1-phenylethanol to acetophenone (model reaction). Attractive green features of these catalytic systems include the operation in aqueous or solvent-free reaction medium, under mild conditions and with high yields and selectivities, using Cu catalyst precursors that are readily available by self-assembly in water of simple chemicals. PMID:20844801

  9. A multiprotein complex that interacts with RNA polymerase II elongator.

    PubMed

    Li, Y; Takagi, Y; Jiang, Y; Tokunaga, M; Erdjument-Bromage, H; Tempst, P; Kornberg, R D

    2001-08-10

    A three-subunit Hap complex that interacts with the RNA polymerase II Elongator was isolated from yeast. Deletions of genes for two Hap subunits, HAP1 and HAP3, confer pGKL killer-insensitive and weak Elongator phenotypes. Preferential interaction of the Hap complex with free rather than RNA polymerase II-associated Elongator suggests a role in the regulation of Elongator activity. PMID:11390369

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

    PubMed

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

    2015-06-01

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

  11. Interaction of RNA polymerase II with acetylated nucleosomal core particles

    SciTech Connect

    Pineiro, M.; Gonzalez, P.J.; Hernandez, F.; Palacian, E. )

    1991-05-31

    Chemical acetylation of nucleosomal cores is accompanied by an increase in their efficiency as in vitro transcription templates. Low amounts of acetic anhydride cause preferential modification of the amino-terminal tails of core histones. Modification of these domains, which causes moderate structural effects, is apparently correlated with the observed stimulation of RNA synthesis. In contrast, extensive modification of the globular regions of core histones, which is accompanied by a large structural relaxation of the particle, causes little additional effect on transcription. Acetylation of the amino-terminal domains of histones might stimulate transcription by changing the interaction of the histone tails with components of the transcriptional machinery.

  12. 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.

  13. Perispeckles are major assembly sites for the exon junction core complex

    PubMed Central

    Daguenet, Elisabeth; Baguet, Aurélie; Degot, Sébastien; Schmidt, Ute; Alpy, Fabien; Wendling, Corinne; Spiegelhalter, Coralie; Kessler, Pascal; Rio, Marie-Christine; Le Hir, Hervé; Bertrand, Edouard; Tomasetto, Catherine

    2012-01-01

    The exon junction complex (EJC) is loaded onto mRNAs as a consequence of splicing and regulates multiple posttranscriptional events. MLN51, Magoh, Y14, and eIF4A3 form a highly stable EJC core, but where this tetrameric complex is assembled in the cell remains unclear. Here we show that EJC factors are enriched in domains that we term perispeckles and are visible as doughnuts around nuclear speckles. Fluorescence resonance energy transfer analyses and EJC assembly mutants show that perispeckles do not store free subunits, but instead are enriched for assembled cores. At the ultrastructural level, perispeckles are distinct from interchromatin granule clusters that may function as storage sites for splicing factors and intermingle with perichromatin fibrils, where nascent RNAs and active RNA Pol II are present. These results support a model in which perispeckles are major assembly sites for the tetrameric EJC core. This subnuclear territory thus represents an intermediate region important for mRNA maturation, between transcription sites and splicing factor reservoirs and assembly sites. PMID:22419818

  14. Perispeckles are major assembly sites for the exon junction core complex.

    PubMed

    Daguenet, Elisabeth; Baguet, Aurélie; Degot, Sébastien; Schmidt, Ute; Alpy, Fabien; Wendling, Corinne; Spiegelhalter, Coralie; Kessler, Pascal; Rio, Marie-Christine; Le Hir, Hervé; Bertrand, Edouard; Tomasetto, Catherine

    2012-05-01

    The exon junction complex (EJC) is loaded onto mRNAs as a consequence of splicing and regulates multiple posttranscriptional events. MLN51, Magoh, Y14, and eIF4A3 form a highly stable EJC core, but where this tetrameric complex is assembled in the cell remains unclear. Here we show that EJC factors are enriched in domains that we term perispeckles and are visible as doughnuts around nuclear speckles. Fluorescence resonance energy transfer analyses and EJC assembly mutants show that perispeckles do not store free subunits, but instead are enriched for assembled cores. At the ultrastructural level, perispeckles are distinct from interchromatin granule clusters that may function as storage sites for splicing factors and intermingle with perichromatin fibrils, where nascent RNAs and active RNA Pol II are present. These results support a model in which perispeckles are major assembly sites for the tetrameric EJC core. This subnuclear territory thus represents an intermediate region important for mRNA maturation, between transcription sites and splicing factor reservoirs and assembly sites. PMID:22419818

  15. 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. PMID:23923794

  16. Forbidden O II studies of galactic planetary nebulae and extragalactic H II complexes

    NASA Astrophysics Data System (ADS)

    Odell, C. R.; Castaneda, H. O.

    1984-08-01

    The 3727-A doublet ratio of forbidden O II was observed in five planetary nebulae and nine extragalactic groupings of H II regions (H II Complexes). The theoretical relation between this doublet ratio and nebular density was rederived using the most up-to-date atomic parameters, permitting columnar densities to be determined for all objects. The structure of extragalactic H II Complexes is discussed, and a preferred model advanced. A new method of distance determination for extragalactic systems is proposed and evaluated in the context of the presently available data.

  17. Stereochemistry of lead(II) complexes with oxygen donor ligands.

    SciTech Connect

    Stavilla, Vitalie; Davidovich, Ruven L.; Whitmire, Kenton Herbert; Voit, Elena I.; Marinin, Dmitry V.

    2008-10-01

    This review discusses the coordination number (CN) and the coordination geometry of the first coordination sphere of Pb(II) atoms in crystal structures of 98 lead(II) complexes with O-donor ligands and the stereochemically active lone pair of electrons (LP, E) in the terms of the valence shell electron-pair repulsion (VSEPR) model. The CN of Pb(II) atoms of the first coordination sphere has values falling into the range (3 + E) to (6 + E). The following coordination polyhedra-{psi}-tetrahedron (I), {psi}-trigonal bipyramid (II), {psi}-octahedron (III), {psi}-pentagonal bipyramid with an axial (IV) or equatorial (V) vacant position are formed. For the investigated structures of the Pb(II) complexes, the formula of each compound, the overall CN of the Pb(II) atom considered as the sum of the CN in the first coordination sphere and the number of secondary bonds, the polyhedron shape, the Pb-O bond lengths, and O-Pb-O bond angles in the first coordination sphere, secondary bond lengths, references and REFCODEs are presented in the comprehensive Tables. The quantum chemical investigations performed using density functional theory (DFT) method have confirmed the stereochemical activity of the LP of Pb(II) atoms in the studied structures of lead(II) complexes with O-donor ligands.

  18. Mechanisms of mantle exhumation at oceanic core complexes

    NASA Astrophysics Data System (ADS)

    MacLeod, C. J.; Escartin, J.; Dick, H. J. B.; Allerton, S.

    2003-04-01

    Mantle rocks are exposed on the seafloor at many slow-spreading mid-ocean ridges as well as at the ocean-continent transitions of rifted continental margins. Similarities in morphology are evident in the two environments and it is likely that the mechanisms that give rise to exhumation of the mantle are comparable to some degree. We review the processes of deformation and magmatism in two contrasting modern oceanic core complexes and compare it with observations from the Lizard Complex (SW England), which is variously interpreted either as an ancient fragment of slow-spread ocean lithosphere or as a piece of lithosphere from a rifted continental margin. Mantle and lower crustal rocks are exposed at Atlantis Bank, on the SW Indian Ridge, and on corrugated highs north of the Fifteen-Twenty fracture zone on the Mid-Atlantic Ridge. Wireline rock drilling has shown that these ‘oceanic core complex’ massifs are the footwalls of large detachment fault systems. Despite their general similarities the two examples exhibit very different mechanisms of strain localisation, and may represent end-members of a range of processes by which detachment faults may form. At Atlantis Bank widespread high-temperature crystal-plastic (and locally syn-magmatic) deformation of gabbros indicates that the detachment fault did not form and move only during amagmatic phases: instead, a continuous gabbro layer was being formed and accreting in the footwall at the same time as the detachment was active, implying that the 'hot' detachment rooted within or near an active magma chamber. In contrast, evidence for high-temperature deformation on the Fifteen-Twenty detachment fault is absent: fault rocks are instead composed of talc-chlorite-tremolite schists, indicating that deformation took place under greenschist facies conditions and suggesting that fluid circulation accompanied and assisted strain localisation. This 'cold' detachment fault must therefore have rooted and slipped in the shallow

  19. Cohesin regulates major histocompatibility complex class II genes through interactions with MHC-II insulators1

    PubMed Central

    Majumder, Parimal; Boss, Jeremy M.

    2011-01-01

    Cohesin is a multiprotein ringed complex that is most well known for its role in stabilizing the association of sister chromatids between S phase and M. More recently cohesin was found to be associated with transcriptional insulators, elements that are associated with the organization of chromatin into regulatory domains. The human major histocompatibility complex class II (MHC-II) locuscontains ten intergenic elements, termed MHC-II insulators, which bind the transcriptional insulator protein CCCTC transcription factor (CTCF). MHC-II insulators interact with each other forming a base architecture of discrete loops and potential regulatory domains. When MHC-II genes are expressed, their proximal promoter regulatory regions reorganize to the foci established by the interacting MHC-II insulators. MHC-II insulators also bind cohesin, but the functional role of cohesin in regulating this system is not known. Here we show that the binding of cohesin to MHC-II insulators occurred irrespective of MHC-II expression but was required for optimal expression of the HLA-DR and HLA-DQ genes. In a DNA dependent manner, cohesin subunits interacted with CTCF and the MHC-II specific transcription factors RFX and CIITA. Intriguingly, cohesin subunits were important for DNA looping interactions between the HLA-DRA promoter region and a 5’ MHC-II insulator but were not required for interactions between the MHC-II insulators themselves. This latter observation introduces cohesin as a regulator of MHC-II expression by initiating or stabilizing MHC-II promoter regulatory element interactions with the MHC-II insulator elements; events which are required for maximal MHC-II transcription. PMID:21911605

  20. 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…

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

    PubMed

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

    2004-02-01

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

  2. 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).

  3. 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.

  4. 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).

  5. Ruthenium complexes as nitric oxide donors and scavengers. Synthesis and crystal and molecular structure for mer,trans-[RuIICl3(NO+)(N-4-ethylisonicotinate)2], and mer,trans-[RuIIICl3(N-CH3CN)(N-4-ethylisonicotinate)2] as obtained via UV-photochemical activation of {RuII(NO+)}3+-core parent complex in acetonitrile solution

    NASA Astrophysics Data System (ADS)

    Tamasi, Gabriella; Cini, Renzo

    2013-09-01

    The synthesis of mer,trans-[RuIICl3(NO+)(EINT)2] (EINT = N-4-ethylisonicotinate), 1, was achieved by carefully working under ultrapure nitrogen atmosphere, by mixing RuIIICl3(NO)·H2O and EINT (1:2 M ratio in anhydrous ethanol) under stirring and at reflux conditions. Single crystals of 1 suitable for X-ray diffraction XRD techniques were also obtained by slow evaporation of solvent under nitrogen from the mother alcoholic solution. The IR spectrum of the solid (KBr matrixes) showed the characteristic sharp and intense band (1866 cm-1) relevant to the N-O stretching vibration for the nitrosyl ligand (RuIINO+ core). Then, on irradiating at 25 °C a solution of 1 in ultrapure acetonitrile (contained in quartz cuvette) under an UV source (250 throughout 366 nm) a color turning from pink to yellow occurred. After a prolonged irradiation (250 nm for at least 6 h) the cuvette (yellow solution) was stored in a dry nitrogen atmosphere and allowed to slowly concentrate via spontaneous solvent evaporation. The solution produced brown crystals as parallelepipeds, suitable for XRD data collection, that belong to the monoclinic system, C2/c space group, and the molecular structure (mer,trans-[RuIICl3(N-NCCH3)(EINT)2], 2) consists of complex molecules that are mostly paired via stacking interactions that involve the pyridine moiety and through (ethyl)CH3⋯Cl(Ru), (pyridine)CH⋯Cl(Ru) and (ethyl)CH3⋯O(C) hydrogen bond type interactions. The crystals of the parent nitrosyl complex belong to the orthorhombic Pccn space group and the complex molecule has three chlorido ligands in the equatorial positions and two EINT ligands in the axial positions. The nitrosyl ligand occupy two positions that are trans to each other and have half occupancy each.

  6. 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.

  7. 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. PMID:27289447

  8. 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.

  9. 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.

  10. Synthesis, Characterization and Biological Evaluation of Co(II), Cu(II), Ni(II) and Zn(II) Complexes With Cephradine

    PubMed Central

    Jaffery, Maimoon F.

    2000-01-01

    Some Co(II), Cu(II), Ni(II) and Zn(II) complexes of antibacterial drug cephradine have been prepared and characterized by their physical, spectral and analytical data. Cephradine acts as bidentate and the complexes have compositions, [M(L)2X2] where [M = Co(II), Ni(II) and Zn(II), L = cephradine and X = Cl2] showing octahedral geometry, and [M(L)2] where [M = Cu(II), L = cephradine] showing square planar geometry. In order to evaluate the effect of metal ions upon chelation, eephradine and its complexes have been screened for their antibacterial activity against bacterial strains, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. PMID:18475955

  11. 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. PMID:27013332

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

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Kumar, Anil

    2007-12-01

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

  13. Structural studies of six and four coordinate zinc(II), nickel(II) and dioxovanadium(V) complexes with thiosemicarbazones

    NASA Astrophysics Data System (ADS)

    Sreekanth, A.; Sivakumar, S.; Prathapachandra Kurup, M. R.

    2003-07-01

    Three Zn(II) complexes of di-2-pyridyl ketone thiosemicarbazone, an octahedral Ni(II) complex of 2-acetylpyridine hexamethyleneiminyl-3-thiosemicarbazone, and a V(V) complex of 2-acetylpyridine morpholyl-3-thiosemicarbazone were prepared and characterized. Crystal structure of Ni(II) and V(V) complexes are reported. The ligand in the nickel complex is found to coordinate in the thione form with a pseudo octahedral geometry and the vanadium(V) complex has trigonal bipyramidal geometry.

  14. Syntheses and spectroscopic studies on zinc(II) and mercury(II) complexes of isatin-3-thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Akinchan, N. T.; Drożdżewski, P. M.; Holzer, W.

    2002-10-01

    Zinc(II) and mercury(II) complexes were prepared by reacting isatin-3-thiosemicarbazone (ISTSCH) with zinc(II) acetate or mercury(II) bromide. The complexes were characterized by IR, Raman, diffuse reflectance, 1H and 13C NMR spectra and elemental analysis. Tetrahedral structures for Zn(ISTSC) 2 and Hg(ISTSCH)Br 2 are suggested.

  15. 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

  16. 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).

  17. 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.

  18. Synthesis, spectroscopic characterization, thermal analysis and electrical conductivity studies of Mg(II), Ca(II), Sr(II) and Ba(II) vitamin B2 complexes

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; Moussa, Mohamed A. A.; Mohamed, Soha F.

    2011-05-01

    Riboflavin (RF) complexes of Mg(II), Ca(II), Sr(II) and Ba(II) were successfully synthesized. Structures of metal complexes obtained were confirmed and characterized by elemental analysis, molar conductance, and infrared spectra. DC electrical conductivity measurements indicated that the alkaline earth metal (II) complexes of RF ligand are non-electrolytes. Elemental analysis of chelates suggest that the metal(II) ligand ratio is 1:2 with structure formula as [M(RF) 2( X) 2]· nH 2O. Infrared assignments clearly show that RF ligand coordinated as a bidentate feature through azomethine nitrogen of pyrazine ring and C dbnd O of pyrimidine-2,4-dione. Thermal analyses of Mg(II), Ca(II), Sr(II) and Ba(II) complexes were investigated using (TG/DSC) under atmospheric nitrogen between 30 and 800 °C. The surface morphology of the complexes was studied by SEM. The electrical conductivities of RF and its metal complexes were also measured with DC electrical conductivity in the temperature range from room to 483 K.

  19. 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

  20. 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

  1. 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…

  2. Cd(II) and Pb(II) complexes of the polyether ionophorous antibiotic salinomycin

    PubMed Central

    2011-01-01

    Background The natural polyether ionophorous antibiotics are used for the treatment of coccidiosis in poultry and ruminants. They are effective agents against infections caused by Gram-positive microorganisms. On the other hand, it was found that some of these compounds selectively bind lead(II) ions in in vivo experiments, despite so far no Pb(II)-containing compounds of defined composition have been isolated and characterized. To assess the potential of polyether ionophores as possible antidotes in the agriculture, a detailed study on their in vitro complexation with toxic metal ions is required. In the present paper we report for the first time the preparation and the structure elucidation of salinomycin complexes with ions of cadmium(II) and lead(II). Results New metal(II) complexes of the polyether ionophorous antibiotic salinomycin with Cd(II) and Pb(II) ions were prepared and structurally characterized by IR, FAB-MS and NMR techniques. The spectroscopic information and elemental analysis data reveal that sodium salinomycin (SalNa) undergoes a reaction with heavy metal(II) ions to form [Cd(Sal)2(H2O)2] (1) and [Pb(Sal)(NO3)] (2), respectively. Abstraction of sodium ions from the cavity of the antibiotic is occurring during the complexation reaction. Salinomycin coordinates with cadmium(II) ions as a bidentate monoanionic ligand through the deprotonated carboxylic moiety and one of the hydroxyl groups to yield 1. Two salinomycin anions occupy the equatorial plane of the Cd(II) center, while two water molecules take the axial positions of the inner coordination sphere of the metal(II) cation. Complex 2 consists of monoanionic salinomycin acting in polydentate coordination mode in a molar ratio of 1: 1 to the metal ion with one nitrate ion for charge compensation. Conclusion The formation of the salinomycin heavy metal(II) complexes indicates a possible antidote activity of the ligand in case of chronic/acute intoxications likely to occur in the stock farming

  3. Cadmium(II) Complex Formation with Cysteine and Penicillamine

    PubMed Central

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

    2009-01-01

    The complex formation between cadmium(II) and the ligands cysteine (H2Cys) or penicillamine (H2Pen = 3, 3′-dimethylcysteine) in aqueous solutions, containing CCd(II) ∼ 0.1 mol dm-3 and CH2L = 0.2 – 2 mol dm-3, was studied at pH = 7.5 and 11.0 by means of 113Cd-NMR and Cd K- and L3-edge X-ray absorption spectroscopy. For all cadmium(II)-cysteine mole ratios the mean Cd-S and Cd-(N/O) bond distances were found in the ranges 2.52 – 2.54 Å and 2.27 – 2.35 Å, respectively. The corresponding cadmium(II)-penicillamine complexes showed slightly shorter Cd-S bonds, 2.50 – 2.53 Å, but with the Cd-(N/O) bond distances in a similar wide range, 2.28 – 2.33 Å. For the mole ratio CH2L / CCd(II) = 2, the 113Cd chemical shifts, in the range 509 – 527 ppm at both pH values, indicated complexes with distorted tetrahedral CdS2N(N/O) coordination geometry. With a large excess of cysteine (mole ratios CH2Cys / CCd(II) ≥ 10) complexes with CdS4 coordination geometry dominate, consistent with the 113Cd NMR chemical shifts, δ ∼ 680 ppm at pH 7.5 and 636 - 658 ppm at pH 11.0, and their mean Cd-S distances of 2.53 ± 0.02 Å. 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, and at pH 11.0 a minor amount of the [Cd(Cys)3]4- complex with CdS3N coordination is formed. For the corresponding penicillamine solutions with mole ratios CH2Pen / CCd(II) ≥ 10, the 113Cd-NMR chemical shifts, δ ∼ 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 Å and Cd-O 2.30 – 2.33 Å, indicate that [Cd(penicillaminate)3]n- complexes with chelating CdS3(N/O) coordination dominate already at pH 7.5, and become mixed with CdS2N(N/O) complexes at pH 11.0. The present study reveals differences between cysteine and penicillamine as ligands to the cadmium(II) ion that can explain why cysteine-rich metallothionines

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

    PubMed

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

    2009-07-01

    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

  5. 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.

  6. 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…

  7. Relations between the photospheric magnetic field and the emission from the outer atmospheres of cool stars. I - The solar Ca II K line core emission

    NASA Technical Reports Server (NTRS)

    Schrijver, C. J.; Cote, J.; Zwaan, C.; Saar, S. H.

    1989-01-01

    Observations of a solar active region complex and its surroundings are used to establish a quantitative relation between the Ca II K line core intensity and magnetic flux density. The Ca II K line core intensity is transformed to a Ca II H + K line core flux density to facilitate a comparison of solar and stellar data. A new absolute calibration for the Mount Wilson Ca II H + K fluxes for G-type dwarfs is derived. The minimum Ca II K flux, found in the centers of supergranulation cells in quiet regions on the sun, is identical to the minimum flux that is observed for solar-type stars. An expression is presented for the nonlinear trend between the Ca II H + K line core excess flux density and the absolute value of the magnetic flux density. Models that explain the nonlinearity of the mean trend and the large intrinsic scatter about it are discussed. The solar data define a relation that is similar to the relation between stellar hemisphere-average magnetic flux densities and Ca II H + K excess flux densities.

  8. Spectral, thermal, electrochemical and analytical studies on Cd(II) and Hg(II) thiosemicarbazone complexes

    NASA Astrophysics Data System (ADS)

    El-Asmy, A. A.; El-Gammal, O. A.; Saleh, H. S.

    2008-11-01

    The coordination characteristic of the investigated thiosemicarbazones towards hazard pollutants, Cd(II) and Hg(II), becomes the first goal. Their complexes have been studied by microanalysis, thermal, electrochemical and spectral (electronic, IR and MS) studies. The substitutent (salicylaldehyde, acetophenone, benzophenone, o-hydroxy- p-methoxybenzophenone or diacetylmonoxime) plays an important role in the complex formation. The coordination sites were the S for thiosemicarbazide (HTS); NN for benzophenone thiosemicarbazone (HBTS); NS for acetophenone thiosemicarbazone (HATS) and salicylaldehyde thiosemicarbazone (H 2STS); NNS or NSO for diacetylmonoxime thiosemicarbazone (H 2DMTS). The stability constants of Hg(II) complexes were higher than Cd(II). The kinetic and thermodynamic parameters for the different thermal decomposition steps in the complexes have been evaluated. The activation energy values of the first step ordered the complexes as: [Cd(H 2STS)Cl 2]H 2O > [Cd(H 2DAMTS)Cl 2] > [Cd(HBTS) 2Cl 2]2H 2O > [Cd(HATS) 2Cl 2]. The CV of [Cd(H 2STS)Cl 2]H 2O and [Hg(HBTS)Cl 2] were recorded. The use of H 2DMTS as a new reagent for the separation and determination of Cd(II) ions from water and some synthetic samples using flotation technique is aimed to be discussed.

  9. Displacement calculations across a metamorphic core complex mylonite zone: Pinaleno Mountains, southeastern Arizona

    SciTech Connect

    Naruk, S.J.

    1987-07-01

    Minimum offset of 7 km across the Pinaleno Mountains metamorphic core complex is calculated by integrating the shear strains across the exposed width of the mylonite zone. The calculated displacement equals the offset on the associated detachment fault, estimated from offset marker beds. The method of determining displacement by strain integration may be directly applicable to many other metamorphic core complexes.

  10. 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. PMID:21763185

  11. 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.

  12. 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.

  13. 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

  14. Stability constants of Ni(II)- and Cu(II)-N-heterocycle complexes according to spectrophotometric data

    NASA Astrophysics Data System (ADS)

    Badhe, Samata; Tekade, Pradip; Bajaj, Sonal; Thakare, Shrikant

    2015-12-01

    The interaction of Ni(II) and Cu(II) with ethyl 4-(4-hydroxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine- 5-carboxylate [Ligand 1], 4-(1H-benzimidazol-2-yl)phenol [Ligand 2], and 2-(3-phenylamino- 4,5-dihydro-1,2-oxazol-5-yl)phenol [Ligand 3] have been studied by spectrophotometric technique at 0.01 M ionic strength and 28°C in 70% dioxane—water mixture. The data obtained were used to estimate the stability constant of these ligands. Spectrophotometric investigation of Ni(II) and Cu(II) complexes with these ligands shows 1: 1 complex formation. The formation of complexes has been studied by Job's variation method. The values of conditional stability constants of Cu(II) complexes are greater than the corresponding Ni(II) complexes. The greater value of stability constant of Cu(II) complexes may be due to the fact of more stable nature of Cu(II). The value of stability constant of Cu(II)—Ligand 2 complex is greater than that of Cu(II)-Ligand 1 and Cu(II)-Ligand 3. The same of Ni(II)-Ligand 3 complex is greater than that of Ni(II)-Ligand 1 and Ni(II)-Ligand 2.

  15. Development of Novel DNA Cleavage Systems Based on Copper Complexes. Synthesis and Characterisation of Cu(II) Complexes of Hydroxyflavones

    PubMed Central

    el Amrani, F. Ben-Allal; Perelló, L.; Torres, L.

    2000-01-01

    Copper(II) complexes of several hydroxyflavones were prepared and characterised through their physico-chemical properties. The nuclease activity of three synthesised complexes is reported. These copper(II) complexes present more nuclease activity than the ligands and the copper(II) ion. PMID:18475969

  16. 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.

  17. Complex Seismic Anisotropy in the Earth's Inner Core Beneath Africa

    NASA Astrophysics Data System (ADS)

    Yu, W.; Wen, L.

    2005-12-01

    Seismic anisotropic velocity structure plays an important role in understanding the geodynamics and mineral physics in the Earth's inner core. Previous seismic studies using the PKiKP-PKIKP phase pairs have suggested no evidence for the presence of anisotropy in velocity in the top 80 km of the inner core. However, the sampling coverage of the PKiKP-PKIKP phase pairs in previous studies was limited, especially along the polar paths. Here we expand our PKiKP-PKIKP dataset by collecting the PKiKP-PKIKP waveforms sampling the inner core globally and along various sampling directions. Our data are selected from the Global Seismographic Network and many regional seismic networks: GEOSCOPE, GEOFON, the Canadian National Seismic Network (CNCN), the Oceanographic Hemisphere Project (OHP), Kazakhstan, and Kyrgyzstan. Our seismic observations show that there is indeed no difference in PKiKP-PKIKP differential travel time residual between the polar and equatorial paths in most regions of the inner core, suggesting no anisotropy in velocity in the top 80 km of the inner core in most regions. Our expanded collection of the PKiKP-PKIKP phases, however, reveals a clear polar-equatorial difference in differential travel time residual in a localized region in the western hemisphere beneath Africa. The PKiKP-PKIKP data sampling along the polar paths in this area of the inner core also exhibit strong lateral variations, requiring the thickness of isotropic layer varying from 10 km or less beneath Uganda and western Africa to 50 km beneath Cameron and Congo. We will show the seismic data grouped according to their sampling regions in the inner core and anisotropic velocity models in each of these regions by waveform modeling the PKiKP-PKIKP data, the PKP data observed at the caustics distance range (141°-145°), and the PKPbc-PKIKP data recorded at larger distances.

  18. Computational molecular characterization of the flavonoid Morin and its Pt(II), Pd(II) and Zn(II) complexes.

    PubMed

    Payán-Gómez, Sergio A; Flores-Holguín, Norma; Pérez-Hernández, Antonino; Piñón-Miramontes, Manuel; Glossman-Mitnik, Daniel

    2011-05-01

    In this work, we make use of a model chemistry within density functional theory (DFT) recently presented, which is called M05-2X, to calculate the molecular structure of the flavonoid Morin and its Pt(II), Pd(II) and Zn(II) complexes, as well to predict their IR and UV-Vis spectra, the dipole moment and polarizability, the free energy of solvation in different solvents as an indication of solubility, the HOMO and LUMO orbitals, and the chemical reactivity parameters that arise from Conceptual DFT. The calculated values are compared with the available experimental data for these molecules. PMID:20628776

  19. Career Ladders and Core Curriculum in Human Services. Phase II Final Report.

    ERIC Educational Resources Information Center

    Soong, Robert K.

    This portion of Phase II of the Social Service Aide Project, a program of exemplary education for the career development of paraprofessionals in social and/or human services, represented an attempt to broaden the career ladders developed during Phase I and to extend the core curriculum above and below the Associate in Arts degree. The scheme of…

  20. Palladium(II) complexes of 1,10-phenanthroline: Synthesis and X-ray crystal structure determination

    PubMed Central

    Adrian, Rafael A.; Broker, Grant A.; Tiekink, Edward R. T.

    2009-01-01

    Two palladium(II) complexes, [Pd(phen)(N≡CCH3)2][O3SCF3]2 (1) and [Pd(phen)(μ-OH)]2[O3SCF3]2·2H2O (2) (where phen= 1,10-phenanthroline), have been crystallized following the reaction of Pd(phen)Cl2 with silver triflate, Ag(O3SCF3), in acetonitrile and water, respectively. The structures of both complexes are based on a Pd(phen)2+ metal core, with two acetonitrile molecules binding in a monodentate fashion in complex 1 and two hydroxo bridges holding together two cores to form a dimer in complex 2. Additionally, both complexes present a hydrogen bonded 3-D network involving the triflate anions in 1, and water and triflate anions in 2. Both complexes have been characterized by infrared and 1H NMR spectroscopy and their crystal structures determined by X-ray crystallography. PMID:19693286

  1. 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.

  2. 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.

  3. 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.

  4. 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.

    PubMed

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

    2014-08-14

    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, (1)H 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. PMID:24727176

  5. 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.

  6. Five-alkyl-two-thiopyrrolidones as ligands in platinum(II) and palladium(II) complexes

    SciTech Connect

    Shebaldova, A.D.; Bystrenina, V.I.; Bespalova, G.V.; Labunskaya, V.I.

    1985-09-01

    5-alkyl-2-thiopyrrolidones (TP, alkyl = C/sub 3/H/sub 7/, C/sub 4/H/sub 9/, C/sub 5/H/sub 11/) have been used for the first time as ligands for the synthesis of complex compounds. When they are reacted with solutions of Pt(II) and Pd(II) salts in a hydroalcoholic medium with a 2:1 ratio between the reactants, complexes with the general formula M(TP)/sub 2/Cl/sub 2/ are obtained. The composition of the complex compounds has been established on the basis of the data from elemental and thermographic analysis. The complex compounds are nonelectrolytes and have a trans configurations (one band with a frequency of 310-330 cm/sup -1/). With the aid of the methods of quantum chemistry and IR and NMR spectroscopy, it has been established that the coordination of TP with the metal is realized by means of the sulfur atom. A comparison of the electron-donor properties of the 5-substituted thiopyrrolidones and their oxygen-containing analogs has been made. All the complex compounds have moderate antiphage, antibacterial, and antifungal activities. The Pd(II) complexes are catalysts for the dehydrohalogenation of 1,2-dichloro-3-butene to chloroprenes.

  7. Structure determination of picolinato copper(II)-amine complexes

    NASA Astrophysics Data System (ADS)

    Mautner, Franz A.; Massoud, Salah S.

    2007-12-01

    Two series of Cu(II)-picolinato complexes of 1:1 and 3:2 Cu(II)-amine/picolinate namely [Cu(L 1)(pic)]ClO 4 and [Cu 3(L 2) 3(pic) 2(H 2O)](ClO 4) 4· xH 2O or [Cu 3(dpt) 3(pic) 2](ClO 4) 4, where pic = picolinate anion, L 1 = dien (diethylenetriamine), Et 2dien ( N, N-diethyldiethylenetriamine), Medpt (3,3'-diamino- N-methyldipropylamine), L 2 = pmedien ( N, N, N', N″, N″-pentamethyl-diethylenetriamine), TPA (tris(2-pyridylmethyl)amine), and dpt = dipropylenetriamine were synthesized and structurally characterized by electronic and IR spectroscopy. Single crystal X-ray diffraction analysis of the complex [Cu(dien)(pic)]ClO 4 ( 1) reveals its monomeric nature whereas for [Cu 3(pmedien) 3(pic) 2(H 2O)](ClO 4) 4·2H 2O ( 4), it was shown that the complex consists of two subunits of the mononuclear [Cu(pmedien)(pic)] + and the dinuclear [Cu 2(pmedien) 2(pic)(H 2O)] 3+ cations with the perchlorate as counter ions and lattice water molecules. In the mononuclear complexes of 1 and 4 the picolinato anions act as N, O-chelating ligands, whereas N, O, O'-picolinato bridges are observed in the dinuclear [Cu 2(pmedien) 2(pic)(H 2O)] 3+ cations of 4. The aqueous visible spectra of the complexes 1- 6 are consistent with five-coordinate Cu(II) species where distorted square pyramidal geometry (SP) was assigned for complexes 2- 5, trigonal bipyramidal geometry (TBP) for 6 and an intermediate geometry between SP and TBP for 1.

  8. RNA polymerase II ternary transcription complexes generated in vitro.

    PubMed Central

    Ackerman, S; Bunick, D; Zandomeni, R; Weinmann, R

    1983-01-01

    Ternary transcription complexes have been formed with a HeLa cell extract, a specific DNA template, and nucleoside triphosphates. The assay depends on the formation of sarkosyl-resistant initiation complexes which contain RNA polymerase II, template DNA, and radioactive nucleoside triphosphates. Separation from the other elements in the in vitro reaction is achieved by electrophoresis in agarose - 0.25% sarkosyl gels. The mobility of the ternary complexes in this system cannot be distinguished from naked DNA. Formation of this complex is dependent on all parameters necessary for faithful in vitro transcription. Complexes are formed with both the plasmid vector and the specific adenovirus DNA insert containing a eucaryotic promoter. The formation of the complex on the eucaryotic DNA is sequence-dependent. An undecaribonucleotide predicted from the template DNA sequence remains associated with the DNA in the ternary complex and can be isolated if the chain terminator 3'-0-methyl GTP is used, or after T1 ribonuclease treatment of the RNA, or if exogenous GTP is omitted from the in vitro reaction. This oligonucleotide is not detected in association with the plasmid vector. Phosphocellulose fractionation of the extract indicates that at least one of the column fractions required for faithful runoff transcription is required for complex formation. A large molar excess of abortive initiation events was detected relative to the level of productive transcription events, indicating a 40-fold higher efficiency of transcription initiation vs. elongation. Images PMID:6193489

  9. Photophysical properties of amphiphilic ruthenium(II) complexes in micelles.

    PubMed

    Rajkumar, Eswaran; Mareeswaran, Paulpandian Muthu; Rajagopal, Seenivasan

    2014-09-01

    Amphiphilic ruthenium(II) complexes II–IV were synthesized and their photophysical properties were investigated in the presence of anionic (SDS), cationic (CTAB) and neutral (Triton X-100) micelles. The absorption and emission spectral data in the presence of micelles show that these Ru(II) complexes are incorporated in the micelles. There are two types of interaction between complexes I–IV and the micelles: hydrophobic and electrostatic. In the case of cationic micelles (CTAB), the hydrophobic interactions are predominant over electrostatic repulsion for the binding of cationic complexes II–IV with CTAB. In the case of anionic micelles (SDS), electrostatic interactions seem to be important in the binding of II–IV to SDS. Hydrophobic interactions play a dominant role in the binding of II–IV to the neutral micelles, Triton X-100. Based on the steady state and luminescence experiments, the enhancement of luminescence intensity and lifetime in the presence of micelles is due to the protection of the complexes from exposure to water in this environment. PMID:24976590

  10. Near-UV phosphorescent emitters: N-heterocyclic platinum(ii) tetracarbene complexes.

    PubMed

    Unger, Yvonne; Zeller, Alexander; Taige, Maria A; Strassner, Thomas

    2009-06-28

    Although examples of nickel(ii), palladium(ii) and platinum(ii) N-heterocyclic tetracarbene complexes are known in the literature, particularly platinum(ii) tetracarbene complexes are rare. We developed a new synthetic route via biscarbene acetate complexes, which make homoleptic as well as heteroleptic platinum(ii) tetracarbene complexes accessible. The reported photoluminescence data show that these complexes have good quantum yields and photostability and are a promising class of emitters for PhOLEDs. Characterization of the compounds includes a solid-state structure of the homoleptic complex bis(1,1'-diisopropyl-3,3'-methylenediimidazoline-2,2'-diylidene)platinum(ii) dibromide. PMID:19513490

  11. 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.

  12. Vocational Agriculture II Curriculum Guide, 10th Grade. Kansas Vocational Agriculture Education: Basic Core Curriculum II.

    ERIC Educational Resources Information Center

    Pittsburg State Univ., KS. Kansas Vocational Curriculum and Research Center.

    This basic core curriculum for vocational agriculture education contains 35 units of instruction in five content areas: agricultural chemicals (1 unit), leadership (2 units), farm management (5 units), plant and soil science (10 units), animal science (8 units), and farm mechanics (9 units). Each unit follows a typical format that includes…

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

    PubMed

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

    2016-06-01

    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. PMID:27171926

  14. Hydrido carbonyl complexes of osmium(II) and ruthenium(II) containing polypyridyl ligands

    SciTech Connect

    Sullivan, B.P.; Caspar, J.V.; Johnson, S.R.; Meyer, T.J.

    1984-01-01

    Several different synthetic routes have been explored to produce hydrido complexes of Os(II) and Ru(II) containing polypyridyl ligands. The resulting complexes, the majority of which contain coordinated CO, are of three types: cis-(M(chelate)/sub 2/(CO)H)/sup +/, trans-(Os(chelate)(PPh/sub 3/)/sub 2/(CO)H)/sup +/, and (Os(chelate)(diphos)(PR/sub 2/)H)/sup +/ (where M = Ru or Os and chelate is, for example, 2,2'-bipyridine or 1,10-phenanthroline or a related ligand). The electronic, infrared, and NMR spectral properties of the complexes are discussed along with the redox properties of their ground and excited states. An important observation is that the hydride ligand endows the metal to ligand charge-transfer (MLCT) excited states of some of the complexes with strong reducing properties. The ground-state chemistry of the complexes is discussed especially with regard to their use as synthetic precursors to new, highly oxidizing, long-lived MLCT excited states of Os(II)< e.g., (Os/sup III/(bpy/sup -/.)(bpy)(CO)(CH/sub 3/CH))/sup 2 +/. 33 references, 7 figures, 2 tables.

  15. Spectral studies on Co(II), Ni(II) and Cu(II) complexes with thiosemicarbazone (L 1) and semicarbazone (L 2) derived from 2-acetyl furan

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Kumar, Anil

    2007-04-01

    Co(II), Ni(II) and Cu(II) complexes are synthesized with thiosemicarbazone (L 1) and semicarbazone (L 2) 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(NO 3) 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. 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.

  17. Spectroscopic and biological approach of Ni(II) and Cu(II) complexes of 2-pyridinecarboxaldehyde thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Raizada, Smriti; Tyagi, Monika; Sharma, Praveen Kumar

    2008-03-01

    Ni(II) and Cu(II) complexes having the general composition [M(L) 2X 2] [where L = 2-pyridinecarboxaldehyde thiosemicarbazone, M = Ni(II) and Cu(II), X = Cl -, NO 3- and 1/2 SO 42-] have been synthesized. All the metal complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, EPR and electronic spectral studies. The magnetic moment measurements of the complexes indicate that all the complexes are of high-spin type. On the basis of spectral studies an octahedral geometry has been assigned for Ni(II) complexes whereas tetragonal geometry for Cu(II) except [Cu(L) 2SO 4] which posseses five coordinated geometry. The ligand and its metal complexes were screened against phytopathogenic fungi and bacteria in vitro.

  18. Diastereomerization Dynamics of a Bistridentate Ru(II) Complex.

    PubMed

    Jarenmark, Martin; Carlström, Göran; Fredin, Lisa A; Hedberg Wallenstein, Joachim; Doverbratt, Isa; Abrahamsson, Maria; Persson, Petter

    2016-03-21

    The unsymmetrical nature of a new tridentate ligand bis(quinolinyl)-1,3-pyrazole (DQPz) is exploited in a bistridentate Ru(II) complex [Ru(DQPz)2](2+) to elucidate an unexpected dynamic diastereomerism. Structural characterization based on a combination of nuclear magnetic resonance spectroscopy and density functional theory calculations reveals the first quantifiable diastereomerization dynamics for Ru complexes with fully conjugated tridentate heteroaromatic ligands. A mechanism that involves a large-scale twisting motion of the ligands is proposed to explain the dynamic interconversion between the observed diastereomers, and the analysis of both experiments and calculations reveals a potential energy landscape with a transition barrier for the diastereomerization of ∼70 kJ mol(-1). The structural flexibility demonstrated around the central transition metal ion has implications for integration of complexes into catalytic and photochemical applications. PMID:26962970

  19. Biological Screening of a Novel Nickel (II) Tyrosine Complex

    PubMed Central

    Islam, Md. Rafiqul; Islam, S. M. Rafiqul; Noman, Abu Shadat Mohammod; Khanam, Jahan Ara; Ali, Shaikh Mohammad Mohsin; Alam, Shahidul

    2007-01-01

    A newly synthesized Nickel (II) tyrosine complex was screened as potential antimicrobial agent against a number of medically important bacteria (Bacillus subtilis, Streptococcus β-haemolytica, Escherichia coli, Shigella dysenterae) and fungi (Aspergillus fumigatus, Candida albicans, Aspergillus niger, Aspergillus flavus, Penicillium sp.) strains. were used for antifungal activity. The antimicrobial activity was evaluated using the Agar Disc method. Moreover, the minimum inhibitory concentration of the complexes was determined against the same pathogenic bacteria and the values were found between 4~64 µg ml-1. Brine shrimp bioassay was carried out for cytotoxicity measurements of the complexes. The LC50 values were calculated after probit transformation of the resulting mortality data and found to be 6 µg ml-1. PMID:24015064

  20. Dense cores in dark clouds. 10: Ammonia emission in the Perseus molecular cloud complex

    NASA Astrophysics Data System (ADS)

    Ladd, E. F.; Myers, P. C.; Goodman, A. A.

    1994-09-01

    We present a survey for dense material around young IRAS sources in the Perseus molecular cloud complex in the NH3 (J, K)=(1,1) line at 1.3 cm. NH3 emission was detected in eight, and mapped in seven, out of 10 positions chosen for study. The dense cores found typically have lower masses and narrower line widths than cores previously studied in Perseus and are located near sources of lower luminosity. NH3 cores are found throughout the Perseus complex; however, much of the detected dense gas is concentrated into two filamentary 'ridges' located in the western part. As a group, NH3 cores in Perseus have a mean line width of 0.6 km/s, mean radius of 0.12 pc, mean kinetic temperature of 13 K, and mean mass of 9 solar mass. These mean values are larger than the mean values for NH3 cores with associated stars in Taurus, but smaller than the mean values for cores associated with stars in Orion A. Some of the cores in Perseus are 'thermally dominated', with thermal and nonthermal line widths similar to most Taurus cores, while others are 'nonthermally dominated' and are more similar to the cores in Orion A. We conclude that the Perseus complex is intermediate in its star-forming potential between the predominantly low-mass star-producing regions like Taurus and the regions capable of the producing high-mass stars such as Orion A.

  1. 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…

  2. Organometallic cis-Dichlorido Ruthenium(II) Ammine Complexes

    PubMed Central

    Betanzos-Lara, Soledad; Habtemariam, Abraha; Clarkson, Guy J; Sadler, Peter J

    2011-01-01

    Bifunctional neutral half-sandwich RuII complexes of the type [(η6-arene)Ru(NH3)Cl2] where arene is p-cym (1) or bip (2) were synthesised by the reaction of N,N-dimethylbenzylamine (dmba), NH4PF6 and the corresponding RuII arene dimer, and were fully characterised. X-ray crystallographic studies of [(η6-p-cym)Ru(NH3)Cl2]·{(dmba–H)(PF6)} (1a) and [(η6-bip)Ru(NH3)Cl2] (2) show extensive H-bond interactions in the solid state, mainly involving the NH3 and the Cl ligands, as well as weak aromatic stacking interactions. The half-lives for the sequential hydrolysis of 1 and 2 determined by UV/Vis spectroscopy at 310 K ranged from a few minutes for the first aquation to ca. 45 min for the second aquation; the diaqua adducts were the predominant species at equilibrium. Arene loss during the aquation of complex 2 was observed. Upon hydrolysis, both complexes readily formed mono- and di-9-ethylguanine (9-EtG) adducts in aqueous solution at 310 K. The reaction reached equilibrium after ca. 1.8 h in the case of complex 1 and was slower but more complete for complex 2 (before the onset of arene loss at ca. 2.7 h). Complexes 1 and 2 were not cytotoxic towards A2780 human ovarian cancer cells up to the maximum concentration tested (100 μM). PMID:23956682

  3. 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

  4. Structural analysis of complexes formed by ethyl 4-phenylthiocarbamoyl piperazine-1-carboxylate with Ni(II), Zn(II) and Cd(II) through spectroscopic and DFT techniques

    NASA Astrophysics Data System (ADS)

    Prakash, Om; Gautam, Priyanka; Dani, R. K.; Nandi, Abhisikta; Singh, N. K.; Singh, Ranjan K.

    2014-04-01

    A piperazine derivative, ethyl 4-phenylthiocarbamoyl piperazine-1-carboxylate and its Ni(II), Zn(II) and Cd(II) complexes have been synthesized and characterized by elemental analyses, magnetic susceptibility measurement, UV-Visible, FTIR, Raman spectroscopic and DFT methods. The Ni(II) and Zn(II) bind through the N and S sites of the two ligand Heptpc and N site of two pyridine molecules. However, the Cd(II) binds through the only N sites of the two ligand Heptpc and N site of two pyridine molecules. On the basis of various techniques used for the characterizations of the complexes, we found that the most possible geometry of the Ni(II) and Zn(II) complexes are distorted octahedral and of the Cd(II) complex is distorted tetrahedral.

  5. Inhibition of respiratory complex I by copper(ii)-bis(thiosemicarbazonato) complexes.

    PubMed

    Djoko, Karrera Y; Donnelly, Paul S; McEwan, Alastair G

    2014-12-01

    Several copper(ii) complexes of bis(thiosemicarbazones) [Cu(btsc)s] show promise as therapeutics for the treatment of neurological diseases, cancers and bacterial infections. These complexes are thought to act primarily as copper ionophores or "copper boosting" agents, whereby the Cu(II) centre is reduced by cytosolic reductants and Cu(I) is released as "free" or "bioavailable" ion. It is then assumed that the dissociated Cu(I) ion is the species responsible for many of the observed biological effects of Cu(btsc)s. We recently showed that Cu(btsc) complexes inhibited NADH dehydrogenases in the bacterial respiratory chain. In this work, we demonstrate that Cu(btsc) complexes also inhibit mitochondrial respiration and that Complex I in the mitochondrial electron transport chain is a specific target of inhibition. However, bioavailable Cu ions do not appear to contribute to the action of Cu(btsc) as a respiratory inhibitor. Instead, an intact Cu(btsc) molecule may bind reversibly and competitively to the site of ubiquinone binding in Complex I. Our results add to the growing body of evidence that the intact complex may be important in the overall cellular activity of Cu(btsc) complexes and further the understanding of their biological effects as a potential therapeutic. PMID:25366244

  6. Photomagnetism of a series of dinuclear Iron(II) complexes.

    PubMed

    Létard, Jean-François; Carbonera, Chiara; Real, José Antonio; Kawata, Satoshi; Kaizaki, Sumio

    2009-01-01

    Spin crossover: The photomagnetic properties of a series of [{Fe(NCS)(py-X)}(2)(bpypz)(2)] (NCS=thiocyanate, py=pyridine, X=4-Mepy, py, 3-Mepy, 3-Clpy and 3-Brpy, and bpypz=3,5-bis(pyridine-2-yl)pyazolate) binuclear complexes are close to the antiferromagnetic response of [{Fe(NCS)(3,5-dmpy)}(3)(bpypz)(2)] (3,5-dmpy=3,5-dimethylpyrazine), which is characterised by two iron(II) metal ions in a high-spin (HS) electronic configuration (see figure).This paper describes the photomagnetic properties of a series of binuclear iron(II) complexes belonging to the [{Fe(NCS)(py-X)}(2)(bpypz)(2)] family (NCS=thiocyanate; py=pyridine; bpypz=3,5-bis(pyridine-2-yl)pyrazolate; and py-X=4-Mepy (1), py (3), 3-Mepy (4), 3-Clpy (5), and 3-Brpy (6)). All of these complexes display a complete thermal spin transition centred between 100 and 150 K, and undergo the light-induced excited-spin-state trapping (LIESST) effect at low temperatures. The T(LIESST) relaxation temperature of the photoinduced high-spin state for each compound has been determined. For all of the complexes, it has been found that the T(LIESST) curves at low temperature are close to the antiferromagnetic response of the [{Fe(NCS)(3,5-dmpy)}(2)(bpypz)(2)] (3,5-dmpy=3,5-dimethylpyridine) (7) complex that is characterised by two iron(II) metal ions in a HS electronic configuration, giving some evidence of a quantitative low spin-low spin-->high spin-high spin (LS-LS-->HS-HS) photoconversion process. Depending on the nature of the cooperativity, the kinetics have been treated with stretched exponential, simply exponential, or sigmoidal models. Interestingly, this series of dinuclear complexes follows a previously proposed linear relationship between the T(LIESST) and their thermal spin transition temperatures T(1/2): T(LIESST)=T(0)-0.3T(1/2). T(0) for these compounds is equal to 100 K. Based on this, and by using the empirical linear relationship found between the thermal spin transition and the Hammett constant, the HS

  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

    2014-09-10

    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.

  8. 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. PMID:12192406

  9. Dinitrogen activation upon reduction of a triiron(II) complex.

    PubMed

    Lee, Yousoon; Sloane, Forrest T; Blondin, Geneviève; Abboud, Khalil A; García-Serres, Ricardo; Murray, Leslie J

    2015-01-26

    Reaction of a trinuclear iron(II) complex, Fe3 Br3 L (1), with KC8 under N2 leads to dinitrogen activation products (2) from which Fe3 (NH)3 L (2-1; L is a cyclophane bridged by three β-diketiminate arms) was characterized by X-ray crystallography. (1) H NMR spectra of the protonolysis product of 2 synthesized under (14) N2 and (15) N2 confirm atmospheric N2 reduction, and ammonia is detected by the indophenol assay (yield ∼30 %). IR and Mössbauer spectroscopy, and elemental analysis on 2 and 2-1 as well as the tri(amido)triiron(II) 3 and tri(methoxo)triiron 4 congeners support our assignment of the reduction product as containing protonated N-atom bridges. PMID:25504859

  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. 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

  12. 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.

  13. 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.

  14. Spectroscopic characterization of some Cu(II) complexes

    SciTech Connect

    Singh, Puja Sharma, S.

    2014-10-15

    3-hydroxy-4-methoxy benzaldehyde semicarbazone (HMBS) is a biologically active compound which has several potential donor sites. This compound has been used for complexation with Cu(II) ions to synthesize complexes of general formula [Cu(HMBS){sub 2}X{sub 2}] where X is Cl{sup −}, NO{sub 3}{sup −} and CH{sub 3}COO{sup −}. Cu(II) is a d{sup 9} system for which {sup 2}D term is generated. Under O{sub h} symmetry, this term splits into {sup 2}E{sub g} and {sup 2}T{sub 2g}. the ground term {sup 2}Eg is doubly degenerate and hence suffers strong Jahn-Teller effect and accordingly the further splitting of terms occur to lower the symmetry from perfect O{sub h}. Here, the ligand occupies four planar positions while the two axial positions have been varied by using different ions like Cl{sup −}, NO{sub 3}{sup −} and CH{sub 3}COO{sup −}. These variations on the axial positions also add to the distortion in O{sub h} symmetry. Under strong distortion, the electronic spectral band splits into multiplets exhibiting tetragonal distortion in complexes. The extent of distortion has been derived by the derivation of the two radial parameters D{sub s} and D{sub t} from electronic spectral bands. The ESR spectra of complexes reveal the real position of the only unpaired electron of the d{sup 9} system in complexes.

  15. Code System to Calculate Mixed Cores in TRIGA Mark II Research Reactor.

    Energy Science and Technology Software Center (ESTSC)

    2001-08-29

    Version 00 TRIGLAV is a computer program for reactor calculations of mixed cores in a TRIGA Mark II research reactor. It can be applied for fuel element burn-up calculations, for power and flux distributions calculations and for reactivity predictions. The TRIGLAV program requires the WIMS-D4 program with the original WIMS cross-section library extended for TRIGA reactor specific nuclides. This package includes the code TRIGAC, which is a new version of TRIGAP.

  16. Triptycene-based Bis(benzimidazole) Carboxylate-Bridged Biomimetic Diiron(II) Complexes

    PubMed Central

    Li, Yang; Myae Soe, Chan Myae; Wilson, Justin J.; Tuang, Suan Lian; Apfel, Ulf-Peter

    2013-01-01

    A triptycene-based bis(benzimidazole) ester ligand, L3, was designed to enhance the electron donating ability of the heterocyclic nitrogen atoms relative to those of the first generation bis(benzoxazole) analogs, L1 and L2. A convergent synthesis of L3 was designed and executed. Three-component titration experiments using UV-visible spectroscopy revealed that the desired diiron(II) complex could be obtained with a 1:2:1 ratio of L3:Fe(OTf)2(MeCN)2:external carboxylate reactants. X-ray crystallographic studies of two diiron complexes derived in this manner from L3 revealed their formulas to be [Fe2L3(μ-OH)(μ-O2CR)(OTf)2], where R = 2,6-bis(p-tolyl)benzoate (7) or triphenylacetate (8). The structures are similar to that of a diiron complex derived from L1, [Fe2L1(μ-OH)(μ-O2CArTol)(OTf)2] (9) with a notable difference being that, in 7 and 8, the geometry at iron more closely resembles square-pyramidal than trigonal-bipyramidal. Mössbauer spectroscopic analyses of 7 and 8 indicate the presence of high-spin diiron(II) cores. These results demonstrate the importance of substituting benzimidazole for benzoxazole for assembling biomimetic diiron complexes with syn disposition of two N-donor ligands, as found in O2-activating carboxylate-bridged diiron centers in biology. PMID:23585728

  17. Alternative designs for construction of the class II transfer RNA tertiary core.

    PubMed Central

    Nissan, T A; Perona, J J

    2000-01-01

    The structural requirements for assembly of functional class II transfer RNA core regions have been examined by sequence analysis and tested by reconstruction of alternative folds into the tertiary domain of Escherichia coli tRNA(2)Gln. At least four distinct designs have been identified that permit stable folding and efficient synthetase recognition, as assessed by thermal melting profiles and glutaminylation kinetics. Although most large variable-arm tRNAs found in nature possess an enlarged D-loop, lack of this feature can be compensated for by insertion of nucleotides either 3' to the variable loop or within the short acceptor/D-stem connector region. Rare pyrimidines at nt 9 in the core region can be accommodated in the class II framework, but only if specific nucleotides are present either in the D-loop or 3' to the variable arm. Glutaminyl-tRNA synthetase requires one or two unpaired uridines 3' to the variable arm to efficiently aminoacylate several of the class II frameworks. Because there are no specific enzyme contacts in the tRNAGln core region, these data suggest that tRNA discrimination by GlnRS depends in part on indirect readout of RNA sequence information. PMID:11105758

  18. Binuclear ruthenium(II) complexes for amyloid fibrils recognition

    NASA Astrophysics Data System (ADS)

    Hanczyc, Piotr

    2014-12-01

    Metal-organic compounds represent a unique class of biomarkers with promising photophysical properties useful for imaging. Here interactions of insulin fibrils with two binuclear complexes [μ-(11,11‧-bidppz)(phen)4Ru2]4+ (1) and [μ-C4(cpdppz)(phen)4Ru2]4+ (2) are studied by linear dichroism (LD) and fluorescence. These ruthenium(II) compounds could provide a new generation of amyloid binding chromophores with long lived lifetimes, good luminescence quantum yields for the bound molecules and photo-stability useful in multiphoton luminescence imaging.

  19. A branched luminescent multinuclear platinum(II) complex

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Xu, S. J.; Tao, Chi-Hang; Yam, Vivian Wing-Wah; Zhang, Jie

    2011-08-01

    Nonlinear optical properties of luminescent multinuclear platinum(II) complex of branched alkynyls in benzene solution are investigated at room temperature by using two-photon fluorescence (TPF) technique. It is found that the material shows unusual nonlinear optical characteristics under the excitation of near infrared femtosecond laser pulses. The self-focusing of laser beam energy during propagation of the laser pulses in the sample with large nonlinear coefficient for the refractive index is observed. Based on this phenomenon, a new method for measuring the nonlinear coefficient and two-photon absorption cross section of materials is proposed.

  20. Containment performance for the core melt accidents in BWRs with Mark I and Mark II containments

    SciTech Connect

    Perkins, K.R.; Yang, J.W.; Greene, G.A.; Pratt, W.T.; Hofmayer, C.

    1985-01-01

    Most previous risk assessment studies have assumed catastrophic failure of containments for severe accidents which are predicted to exceed the containment yield stress. This investigation analyzes the progression of a severe accident in order to develop realistic containment temperature and pressure loading, utilizes models for containment leakage estimates for the various loading histories, and assesses the expected failure modes and timing of releases for core melt accidents in Boiling Water Reactors (BWRs) with Mark I and Mark II containments. The results of the investigation indicate that leakage through the seal on the drywell head may be sufficient to prevent catastrophic failure of the containments for a wide range of hypothetical core melt scenarios. In addition, the investigation has indicated the potential for a previously inidentified failure mode (containment liner meltthrough) for Mark I containments in which a large fraction of the core is released from the vessel in a molten state. 14 refs.

  1. Structural characterization of some oxalato-bridged copper(II) and nickel(II) complexes

    NASA Astrophysics Data System (ADS)

    Mautner, Franz A.; Louka, Febee R.; Massoud, Salah S.

    2009-03-01

    A new series of dinuclear oxalato-bridged copper(II) and nickel(II) complexes derived from tridentate amines: [Cu 2(Medpt) 2(μ-C 2O 4)](ClO 4) 2 ( 1), [Cu 2(pmedien) 2(μ-C 2O 4)](ClO 4) 2 ( 2), [Cu 2(DPA) 2(μ-C 2O 4)(ClO 4) 2]·2H 2O (3), and [Ni 2(Et 2dien) 2(μ-C 2O 4)(H 2O) 2](ClO 4) 2·2H 2O ( 4) (C 2O 42- = oxalate dianion, Medpt = 3,3'-diamino- N-methyldipropylmine, pmedien = N, N, N', N'', N''-pentamethyldiethylenetriamine, DPA = di(2-pyridylmethyl)amine and Et 2dien = N, N-diethyldiethylenetriamine) were synthesized and structurally characterized by X-ray crystallography. The spectral and structural characterizations of these complexes are reported. In this series, structures consist of the C 2O 42- bridging the two M(II) centers in a bis-bidentate bonding mode. The Cu 2+ centers are coordinated to the tridentate amines Medpt or pmedien in distorted SP geometry in 1 and 2, respectively, with the ClO 4- groups as counter ions. In the other two complexes, distorted octahedral geometries were achieved by the three nitrogen donors of the DPA and by an oxygen atom from coordinated perchlorate ion in 3 and by the Et 2dien and one water molecule in 4.

  2. Reaction mechanism of Ru(II) piano-stool complexes: umbrella sampling QM/MM MD study.

    PubMed

    Futera, Zdeněk; Burda, Jaroslav V

    2014-07-15

    Biologically relevant interactions of piano-stool ruthenium(II) complexes with ds-DNA are studied in this article by hybrid quantum mechanics-molecular mechanics (QM/MM) computational technique. The whole reaction mechanism is divided into three phases: (i) hydration of the [Ru(II) (η(6) -benzene)(en)Cl](+) complex, (ii) monoadduct formation between the resulting aqua-Ru(II) complex and N7 position of one of the guanines in the ds-DNA oligomer, and (iii) formation of the intrastrand Ru(II) bridge (cross-link) between two adjacent guanines. Free energy profiles of all the reactions are explored by QM/MM MD umbrella sampling approach where the Ru(II) complex and two guanines represent a quantum core, which is described by density functional theory methods. The combined QM/MM scheme is realized by our own software, which was developed to couple several quantum chemical programs (in this study Gaussian 09) and Amber 11 package. Calculated free energy barriers of the both ruthenium hydration and Ru(II)-N7(G) DNA binding process are in good agreement with experimentally measured rate constants. Then, this method was used to study the possibility of cross-link formation. One feasible pathway leading to Ru(II) guanine-guanine cross-link with synchronous releasing of the benzene ligand is predicted. The cross-linking is an exergonic process with the energy barrier lower than for the monoadduct reaction of Ru(II) complex with ds-DNA. PMID:24865949

  3. Nucleophilic reactivity of a copper(II)-superoxide complex.

    PubMed

    Pirovano, Paolo; Magherusan, Adriana M; McGlynn, Ciara; Ure, Andrew; Lynes, Amy; McDonald, Aidan R

    2014-06-01

    Metal-bound superoxide intermediates are often implicated as electrophilic oxidants in dioxygen-activating metalloenzymes. In the nonheme iron α-ketoglutarate dependent oxygenases and pterin-dependent hydroxylases, however, Fe(III)-superoxide intermediates are postulated to react by nucleophilic attack on electrophilic carbon atoms. By reacting a Cu(II)-superoxide complex (1) with acyl chloride substrates, we have found that a metal-superoxide complex can be a very reactive nucleophile. Furthermore, 1 was found to be an efficient nucleophilic deformylating reagent, capable of Baeyer-Villiger oxidation of a number of aldehyde substrates. The observed nucleophilic chemistry represents a new domain for metal-superoxide reactivity. Our observations provide support for the postulated role of metal-superoxide intermediates in nonheme iron α-ketoglutarate dependent and pterin-dependent enzymes. PMID:24753290

  4. Photophysical investigation of palladium(II) ortho-metalated complexes

    SciTech Connect

    Craig, C.A.; Watts, R.J. )

    1989-01-25

    Syntheses and structural characterizations of four complexes of Pd(II) with ortho-metalated 2-phenylpyridinate (ppy{sup minus}) are reported. These complexes include a parent dimer, (Pd(ppy)Cl){sub 2}, and three derivative monomers, (Pd(ppy)(bpy))Cl, (Pd(ppy)(en))Cl, and (Pd(ppy)(CO)Cl), whereby = 2,2'-bipyridine and en = ethylenediamine. Photophysical characterizations of these species indicate low-energy absorption bands ({approximately}360 nm) and emission bands at 77 K ({approximately}460 nm) that are assigned to transitions located on the ppy{sup {minus}} ligand. Some evidence for low-energy charge-transfer states is found in trends in luminescence lifetimes. 2 tabs., 5 figs., 21 refs.

  5. An oximate-based hexanuclear mixed-valence Mn(III)4Mn(II)2 edge-sharing bitetrahedral core with an St = 5 spin ground state.

    PubMed

    Khanra, Sumit; Weyhermüller, Thomas; Chaudhuri, Phalguni

    2008-09-28

    The synthesis, structures and magnetic properties of two hexanuclear Mn6 clusters are reported: Mn6(mu4-O)2(dapdo)2(dapdoH)4(mu2-OH)2](ClO4)(2).6MeCN (1.6MeCN) and [Mn6(mu4-O)2(dapdo)2(dapdoH)4(mu2-OCH3)2](ClO4)(2).2Et2O (2.2Et2O) [dapdo2- is the dianion of 2,6-diacetylpyridine dioxime and dapdoH- is the monoanion of the aforesaid dioxime ligand]. Both complexes are mixed-valent with two Mn(II) and four Mn(III) atoms disposed in an edge-sharing bitetrahedral core. Both complexes 1 and 2 display the same [Mn(III)4Mn(II)2(mu4-O)2(mu2-OR)2]10+ core in which R = H for 1 and R = Me for 2. The [Mn(III)4Mn(II)2] core is rather uncommon compared to the reported [Mn(III)2Mn(II)4] core in the literature. DC magnetic susceptibility measurements on 1 and 2 reveal the presence of competing exchange interactions resulting in an St = 5 ground spin state. The magnetic behavior of the compounds indicates antiferromagnetic coupling between the manganese(III) centers, whereas the coupling between the manganese(III) and manganese(II) is weakly antiferromagnetic or ferromagnetic depending on the bridging environments. Finally the interaction between the manganese(II) centers from the two fused tetrahedra is weakly ferromagnetic in nature stabilizing St = 5 ground spin state in compounds 1 and 2. PMID:18766221

  6. 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…

  7. The TOM core complex: the general protein import pore of the outer membrane of mitochondria.

    PubMed

    Ahting, U; Thun, C; Hegerl, R; Typke, D; Nargang, F E; Neupert, W; Nussberger, S

    1999-11-29

    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 approximately 2.1 nm and a height of approximately 7 nm. Tom40 is the key structural element of the TOM core complex. PMID:10579717

  8. 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…

  9. Palladium(II) complexes of diphenylvinyl- and phenyldivinylphosphine

    SciTech Connect

    Rahn, J.A.; Holt, M.S.; O'Neil-Johnson, M.; Nelson, J.H.

    1988-04-20

    Palladium(II) complexes of the ligands L = Ph/sub 2/PCH/double bond/CH/sub 2/ and PhP(CH/double bond/CH/sub 2/)/sub 2/ have been prepared and characterized by elemental analysis, infrared spectroscopy, and /sup 1/H, /sup 1/H(/sup 31/P), /sup 13/C(/sup 1/H), /sup 31/P(/sup 1/H), and /sup 1/H//sup 13/C HETCOR nuclear magnetic resonance spectroscopy. These complexes exist as temperature-dependent equilibrium mixtures of cis and trans isomers in solution. Equilibrium thermodynamics for the isomerization process cis-L/sub 2/PdX/sub 2/ /rightleftharpoons/ trans-L/sub 2/PdX/sub 2/, determined by variable-temperature /sup 31/P(/sup 1/H) NMR spectroscopy, demonstrate that the cis isomers are in general thermodynamically more stable than the trans isomers. However, the relatively isomer stabilities are anion dependent with the trans isomer becoming more stable in the order Cl < Br < I. Coordination of a vinylphosphine to palladium(II) strongly polarizes the C/double bond/C double bond as evidenced by /sup 13/C NMR data. 27 refs., 2 figs., 4 tabs.

  10. Inhibition of Mitochondrial Complex II by the Anticancer Agent Lonidamine.

    PubMed

    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

  11. 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

  12. Binuclear Rhodium(II) Complexes With Selective Antibacterial Activity.

    PubMed

    Bień, M; Lachowicz, T M; Rybka, A; Pruchnik, F P; Trynda, L

    1997-01-01

    Binuclear rhodium(II) complexes [Rh(2)Cl(2)(mu-OOCR)(2)(N-N)(2)] {R = H, Me; N-N = 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen)} and [Rh(2)(mu-OOCR)(2)(N-N)(2)(H(2)O)(2)](RCOO)(2) (R = Me, Et;) have been synthesized and their structure and properties have been studied by electronic, IR and (1)H NMR spectroscopy. Antibacterial activity of these complexes against Escherichia coli and Staphylococcus aureus has been investigated. The most active antibacterial agents against E. coli were [Rh(2)Cl(2)(mu-OOCR)(2)(N-N)(2)] and [Rh(2)(mu-OOCR)(2)(N-N)(2)(H(2)O)(2)](RCOO)(2) {R = H and Me} which were considerably more active than the appropriate nitrogen ligands. The complexes show low activity against S. aureus. The activity of the complexes [Rh(2)(OOCR)(2)(N-N)(2)(H(2)O)(2)](OOCR)(2) against E. coli decreases in the series: R=H congruent withCH(3)>C(2)H(5)>C(3)H(7) congruent withC(4)H(9). The reverse order was found in the case of S. aureus. PMID:18475773

  13. 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. PMID:26214707

  14. A New Program for Detecting the Geometrical Core of a Set of Structures of Macromolecular Complexes.

    PubMed

    Vakulenko, Yu A; Nagaev, B E; Alexeevski, A V; Karyagina, A S; Spirin, S A

    2016-04-01

    Comparison of structures of homological proteins often helps to understand functionally significant features of these structures. This concerns not only structures of separate protein chains, but also structures of macromolecular complexes. In particular, a comparison of complexes of homologous proteins with DNA is significant for analysis of the recognition of DNA by proteins. We present program LCore for detecting geometrical cores of a family of structures; a geometrical core is a set of amino acid residues and nucleotides that disposed similarly in all structures of the family. We describe the algorithm of the program, its web interface, and an example of its application to analysis of complexes of homeodomains with DNA. PMID:27293101

  15. Anionic sulfonated and carboxylated PPI dendrimers with the EDA core: synthesis and characterization of selective metal complexing agents.

    PubMed

    García-Gallego, Sandra; Cangiotti, Michela; Fiorani, Luigi; Fattori, Alberto; Muñoz-Fernández, Ma Ángeles; Gomez, Rafael; Ottaviani, M Francesca; de la Mata, F Javier

    2013-04-28

    Herein we describe the synthesis and characterization of new sulfonated and carboxylated poly(propyleneimino) (PPI) dendrimers with the ethylenediamino (EDA) core, at generations 1, 2 and 3. By means of UV-Vis and EPR spectroscopy, using Cu(2+) as a probe, we concluded that these dendrimers show a specific pattern in the coordination of metal ions. In agreement with the UV-Vis studies, EPR spectra of carboxylated compounds are constituted by 3 different signals which appear and then disappear with increasing copper concentration, corresponding to the saturation of different copper complexation sites. At the lowest copper concentration up to a 1:1 molar ratio between Cu(II) and the dendrimer, the spectrum is characteristic of a CuN2O2 coordination at the core of the dendrimer. The spectrum appearing at higher Cu(II) concentrations indicates a peripheral location of the ions coordinating one nitrogen and 3 oxygen atoms in a square planar geometry in restricted mobility conditions. For the highest concentrations tested, copper ions are confined at the external dendrimer surface with CuO4 coordination. For sulfonate systems, the EPR results are in line with a weaker interaction of Cu(II) with the nitrogen sites and a stronger interaction with the oxygen (SO3(-)) groups with respect to the interactions measured by EPR for carboxylate systems. PMID:23462972

  16. Electrophilic alkylation of pseudotetrahedral nickel(II) arylthiolate complexes.

    PubMed

    Deb, Tapash; Jensen, Michael P

    2015-01-01

    A kinetic study is reported for reactions of pseudotetrahedral nickel(II) arylthiolate complexes [(Tp(R,Me))Ni-SAr] (Tp(R,Me) = hydrotris{3-R-5-methyl-1-pyrazolyl}borate, R = Me, Ph, and Ar = C6H5, C6H4-4-Cl, C6H4-4-Me, C6H4-4-OMe, 2,4,6-Me3C6H2, 2,4,6-(i)Pr3C6H2) with organic electrophiles R'X (i.e., MeI, EtI, BzBr) in low-polarity organic solvents (toluene, THF, chloroform, dichloromethane, or 1,2-dichloroethane), yielding a pseudotetrahedral halide complex [(Tp(R,Me))Ni-X] (X = Cl, Br, I) and the corresponding organosulfide R'SAr. Competitive reactions with halogenated solvents and adventitious air were also examined. Akin to reactions of analogous and biomimetic zinc complexes, a pertinent mechanistic question is the nature of the reactive nucleophile, either an intact thiolate complex or a free arylthiolate resulting from a dissociative pre-equilibrium. The observed kinetics conformed to a second-order rate law, first order with respect to the complex and electrophile, and no intermediate complexes were observed. In the absence of a mechanistically diagnostic rate law, a variety of mechanistic probes were examined, including kinetic effects of varying the metal, solvent, electrophile, and temperature, as well as the 3-pyrazolyl and arylthiolate substituents. Compared to zinc analogues, the effect of Ni-SAr covalency is also of interest herein. The results are broadly interpreted with respect to the disparate mechanistic pathways. PMID:25494529

  17. Disturbed excitation energy transfer in Arabidopsis thaliana mutants lacking minor antenna complexes of photosystem II.

    PubMed

    Dall'Osto, Luca; Ünlü, Caner; Cazzaniga, Stefano; van Amerongen, Herbert

    2014-12-01

    Minor light-harvesting complexes (Lhcs) CP24, CP26 and CP29 occupy a position in photosystem II (PSII c' plants between the major light-harvesting complexes LHCII and the PSII core subunits. Lack of minor Lhcs in vivo causes impairment of PSII organization, and negatively affects electron transport rates anc photoprotection capacity. Here we used picosecond-fluorescence spectroscopy to study excitation-energy transfer (EET) in thylakoid membranes isolated from Arabidopsis thaliana wild-type plants and knockout lines depleted of either two (koCP26/24 and koCP29/24) or all minor Lhcs (NoM). In the absence of all minor Lhcs. the functional connection ofLHCII to the PSII cores appears to be seriously impaired whereas the "disconnected" LHCII is substantially quenched. For both double knock-out mutants, excitation trapping in PSII is faster than in NoM thylakoids but slower than in WT thylakoids. In NoM thylakoids, the loss of all minor Lhcs is accompanied by an over-accumulation ofLHCII, suggesting a compensating response to the reduced trapping efficiency in limiting light, which leads to a photosynthetic phenotype resembling that of low-light-acclimated plants. Finally. fluorescence kinetics and biochemical results show that the missing minor complexes are not replaced by other Lhcs, implying that they are unique among the antenna subunits and crucial for the functioning and macroorganization of PSII. PMID:25291424

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

    PubMed

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

    2015-11-01

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

  19. 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.

  20. 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. PMID:20960125

  1. 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…

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

    PubMed

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

    2002-05-21

    A spectrophotometric study of the complexation of nifuroxazide with cobalt(II), nickel(II) and copper(II) was carried out in different alcohols. The formation of a complex in each case is reported and their stability constants have been calculated. For a given solvent, the stability of the complexes increases from cobalt to copper. In the case of copper(II), the stability varies as an inverse function of the dielectric constant of the solvent. A possible structure of the complex is proposed. PMID:12009257

  3. Complex permeability and core loss of soft magnetic Fe-based nanocrystalline powder cores

    NASA Astrophysics Data System (ADS)

    Füzerová, Jana; Füzer, Ján; Kollár, Peter; Bureš, Radovan; Fáberová, Mária

    2013-11-01

    Rapidly quenched ribbons of Fe73Cu1Nb3Si16B7 were ball milled and cryomilled to get powder and warm consolidated to get bulk compacts. The data presented here are relative to different experimental procedures, one corresponding to milling at room temperature (sample R1) and the other corresponding to cryomilling at temperature of liquid nitrogen (sample L1). It was found that the properties of the initial powder influenced the density, the electrical resistivity and electromagnetic properties of the resulting bulk alloys. Permeability and core loss are structure sensitive and depend on factors such as powder size and shape, porosity, purity, and internal stress. Permeability spectra of sample R1 decreases with increasing the frequency and its values are larger than that for sample L1 at low frequencies. On the other hand the permeability of sample L1 remains steady up to 1 kHz and at certain frequency is larger than that for sample R1. Also there are different frequency dependences of the imaginary parts of permeability and loss factor, respectively. The cryomilling of the amorphous ribbon positively influences on the AC magnetic properties at higher frequencies (above 100 Hz) of resulting bulk sample.

  4. In Vivo Identification of Photosystem II Light Harvesting Complexes Interacting with PHOTOSYSTEM II SUBUNIT S.

    PubMed

    Gerotto, Caterina; Franchin, Cinzia; Arrigoni, Giorgio; Morosinotto, Tomas

    2015-08-01

    Light is the primary energy source for photosynthetic organisms, but in excess, it can generate reactive oxygen species and lead to cell damage. Plants evolved multiple mechanisms to modulate light use efficiency depending on illumination intensity to thrive in a highly dynamic natural environment. One of the main mechanisms for protection from intense illumination is the dissipation of excess excitation energy as heat, a process called nonphotochemical quenching. In plants, nonphotochemical quenching induction depends on the generation of a pH gradient across thylakoid membranes and on the presence of a protein called PHOTOSYSTEM II SUBUNIT S (PSBS). Here, we generated Physcomitrella patens lines expressing histidine-tagged PSBS that were exploited to purify the native protein by affinity chromatography. The mild conditions used in the purification allowed copurifying PSBS with its interactors, which were identified by mass spectrometry analysis to be mainly photosystem II antenna proteins, such as LIGHT-HARVESTING COMPLEX B (LHCB). PSBS interaction with other proteins appears to be promiscuous and not exclusive, although the major proteins copurified with PSBS were components of the LHCII trimers (LHCB3 and LHCBM). These results provide evidence of a physical interaction between specific photosystem II light-harvesting complexes and PSBS in the thylakoids, suggesting that these subunits are major players in heat dissipation of excess energy. PMID:26069151

  5. 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

  6. Examination of the Impact of Copper(II) α-(N)-Heterocyclic Thiosemicarbazone Complexes on DNA Topoisomerase IIα.

    PubMed

    Wilson, James T; Jiang, Xiaohua; McGill, Bradley C; Lisic, Edward C; Deweese, Joseph E

    2016-04-18

    Type II DNA topoisomerases resolve topological knots and tangles in DNA that result from routine cellular processes and are effective targets for anticancer therapeutics. To this end, thiosemicarbazones have been identified as having the ability to kill cancer cells from several cell lines. Literature evidence suggests that at least some thiosemicarbazones have an impact on topoisomerase II activity. However, the mechanism is not as clearly defined. Therefore, we set out to analyze the activity of four α-(N)-heterocyclic thiosemicarbazone compounds against topoisomerase IIα. The ligands, acetylpyridine-ethylthiosemicarbazone (APY-ETSC) and acetylpyrazine-methylthiosemicarbazone (APZ-MTSC), and their copper(II) [Cu(II)] complexes [Cu(APY-ETSC)Cl] and [Cu(APZ-MTSC)Cl] were examined for the ability to impact the catalytic cycle of human topoisomerase IIα. Both [Cu(APY-ETSC)Cl] and [Cu(APZ-MTSC)Cl] were more effective at inhibiting DNA relaxation compared with the ligands alone. Further, both [Cu(APY-ETSC)Cl] and [Cu(APZ-MTSC)Cl] increased double-stranded DNA cleavage levels without inhibiting topoisomerase IIα-mediated DNA ligation. The Cu(II) complexes inactivate enzyme activity over time suggesting a critical interaction with the enzyme. Additionally, we found that the Cu(II)-thiosemicarbazone complexes do not significantly impact DNA cleavage by the catalytic core of the enzyme. This evidence is supported by the fact that both [Cu(APY-ETSC)Cl] and [Cu(APZ-MTSC)Cl], and to a lesser extent the ligands, inhibit topoisomerase IIα-mediated ATP hydrolysis. Based upon kinetic analysis, the Cu(II) complexes appear to be noncompetitive inhibitors of the ATPase domain of topoisomerase IIα. Taken together, our results provide evidence that Cu(II) complexes of α-(N)-heterocyclic thiosemicarbazones catalytically inhibit the enzyme through the ATPase domain but also promote double-stranded DNA cleavage by the enzyme. PMID:26982206

  7. Ni(II) affects ubiquitination of core histones H2B and H2A

    SciTech Connect

    Karaczyn, Aldona A.; Golebiowski, Filip; Kasprzak, Kazimierz S. . E-mail: kasprkaz@mail.ncifcrf.gov

    2006-10-15

    The molecular mechanisms of nickel-induced malignant cell transformation include effects altering the structure and covalent modifications of core histones. Previously, we found that exposure of cells to Ni(II) resulted in truncation of histones H2A and H2B and thus elimination of some modification sites. Here, we investigated the effect of Ni(II) on one such modification, ubiquitination, of histones H2B and H2A in nuclei of cultured 1HAEo- and HPL1D human lung cells. After 1-5 days of exposure, Ni(II) up to 0.25 mM stimulated mono-ubiquitination of both histones, while at higher concentrations a suppression was found. Di-ubiquitination of H2A was not affected except for a drop after 5 days at 0.5 mM Ni(II). The decrease in mono-ubiquitination coincided with the appearance of truncated H2B that lacks the K120 ubiquitination site. However, prevention of truncation did not avert the decrease of H2B ubiquitination, indicating mechanistic independence of these effects. The changes in H2B ubiquitination did not fully coincide with concurrent changes in the nuclear levels of the ubiquitin-conjugating enzymes Rad6 and UbcH6. Overall, our results suggest that dysregulation of H2B ubiquitination is a part of Ni(II) adverse effects on gene expression and DNA repair which may assist in cell transformation.

  8. The coactivator dTAF(II)110/hTAF(II)135 is sufficient to recruit a polymerase complex and activate basal transcription mediated by CREB.

    PubMed

    Felinski, E A; Quinn, P G

    2001-11-01

    A specific TATA binding protein-associated factor (TAF), dTAF(II)110/hTAF(II)135, interacts with cAMP response element binding protein (CREB) through its constitutive activation domain (CAD), which recruits a polymerase complex and activates transcription. The simplest explanation is that the TAF is a coactivator, but several studies have questioned this role of TAFs. Using a reverse two-hybrid analysis in yeast, we previously mapped the interaction between dTAF(II)110 (amino acid 1-308) and CREB to conserved hydrophobic amino acid residues in the CAD. That mapping was possible only because CREB fails to activate transcription in yeast, where all TAFs are conserved, except for the TAF recognizing CREB. To test whether CREB fails to activate transcription in yeast because it lacks a coactivator, we fused dTAF(II)110 (amino acid 1-308) to the TATA binding protein domain of the yeast scaffolding TAF, yTAF(II)130. Transformation of yeast with this hybrid TAF conferred activation by the CAD, indicating that interaction with yTFIID is sufficient to recruit a polymerase complex and activate transcription. The hybrid TAF did not mediate activation by VP16 or vitamin D receptor, each of which interacts with TFIIB, but not with dTAF(II)110 (amino acid 1-308). Enhancement of transcription activation by dTAF(II)110 in mammalian cells required interaction with both the CAD and TFIID and was inhibited by mutation of core hydrophobic residues in the CAD. These data demonstrate that dTAF(II)110/hTAF(II)135 acts as a coactivator to recruit TFIID and polymerase and that this mechanism of activation is conserved in eukaryotes. PMID:11687654

  9. Spectroscopic investigation of the structure of complex compounds of Cu(II), Co(II), and Ni(II) with. cap alpha. - and. beta. -diketone

    SciTech Connect

    Krymova, N.M.; Ivanov, V.E.; Ostapkevich, N.A.

    1986-11-10

    In the reactions of Cu(II), Co(II), and Ni(II) chlorides with 2,3-butanedione and 2,4-pentanedione isonicotinoylhydrazones in neutral and weakly acid media complex compounds of the addition-product type are formed, but in an alkaline medium inner-complex compounds are formed. By methods of electronic and ESR spectroscopy it was shown that the Cu(II) complex compounds have a planar-square structure, the Ni(II) complexes are octrahedral, but the Co(II) complexes have a tetrahedral or distorted tetrahedral structure. In the spectrochemical series 2,3-butanedione and 2,4-pentanedione isonicotinoylhydrazones occupy positions between water and ammonia.

  10. Palladium(II) complexes featuring a mixed phosphine-pyridine-iminophosphorane pincer ligand: synthesis and reactivity.

    PubMed

    Cheisson, Thibault; Auffrant, Audrey

    2016-02-01

    An original mixed ligand (labelled L) of formula PPh2-CH2-Pyr-CH2-N[double bond, length as m-dash]PPh3, combining a pyridine core with phosphine and iminophosphorane, was synthesised. Its coordination with palladium(II) centers was studied. With [Pd(COD)Cl2], a cationic complex [LPdCl](Cl) 1, where L is coordinated in the pincer mode, was obtained. Chloride abstraction with silver salt in the presence of pyridine generated the dicationic complex [LPd(py)](BF4)2 (2). When reacting with a base such as potassium hexamethyldisilazane (KHMDS), 1 gave the neutral complex 3 [L*PdCl], wherein the benzylic position alpha to phosphine was selectively deprotonated, which induced dearomatisation of the pyridine ring. A similar complex [L*Pd(CH3)] (4) was obtained upon a reaction of [Pd(CH3)2(TMEDA)] and Lvia the departure of methane. Neutral complexes with the deprotonated ligand such as 3 yielded in the presence of deuterated methanol the corresponding deuterated complex, showing that the protonation is reversible with this ligand. Finally, upon attempting to dealkylate complex 4 using B(C6F5)3, an unexpected zwitterionic borated complex 5, resulting from the formation of a C-B bond in the benzylic position with restoration of the aromatic character of the pyridine, was isolated. Interestingly, when the metal was introduced after the ligand interacted with the borane reagent, another palladium complex formed, namely, [LPdMe][MeB(C6F5)3], originating from methyl abstraction. PMID:26419539

  11. 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.

  12. 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.

  13. 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. PMID:20960116

  14. Structure of an RNA polymerase II preinitiation complex

    PubMed Central

    Murakami, Kenji; Tsai, Kuang-Lei; Kalisman, Nir; Bushnell, David A.; Asturias, Francisco J.; Kornberg, Roger D.

    2015-01-01

    The structure of a 33-protein, 1.5-MDa RNA polymerase II preinitiation complex (PIC) was determined by cryo-EM and image processing at a resolution of 6–11 Å. Atomic structures of over 50% of the mass were fitted into the electron density map in a manner consistent with protein–protein cross-links previously identified by mass spectrometry. The resulting model of the PIC confirmed the main conclusions from previous cryo-EM at lower resolution, including the association of promoter DNA only with general transcription factors and not with the polymerase. Electron density due to DNA was identifiable by the grooves of the double helix and exhibited sharp bends at points downstream of the TATA box, with an important consequence: The DNA at the downstream end coincides with the DNA in a transcribing polymerase. The structure of the PIC is therefore conducive to promoter melting, start-site scanning, and the initiation of transcription. PMID:26483468

  15. Structure of an RNA polymerase II preinitiation complex.

    PubMed

    Murakami, Kenji; Tsai, Kuang-Lei; Kalisman, Nir; Bushnell, David A; Asturias, Francisco J; Kornberg, Roger D

    2015-11-01

    The structure of a 33-protein, 1.5-MDa RNA polymerase II preinitiation complex (PIC) was determined by cryo-EM and image processing at a resolution of 6-11 Å. Atomic structures of over 50% of the mass were fitted into the electron density map in a manner consistent with protein-protein cross-links previously identified by mass spectrometry. The resulting model of the PIC confirmed the main conclusions from previous cryo-EM at lower resolution, including the association of promoter DNA only with general transcription factors and not with the polymerase. Electron density due to DNA was identifiable by the grooves of the double helix and exhibited sharp bends at points downstream of the TATA box, with an important consequence: The DNA at the downstream end coincides with the DNA in a transcribing polymerase. The structure of the PIC is therefore conducive to promoter melting, start-site scanning, and the initiation of transcription. PMID:26483468

  16. 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. PMID:26190176

  17. 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

  18. Complexes with Hg(II) and macrocyclic ligands

    SciTech Connect

    Luis, S.V.; Frias, J.C.; Salvador, R.V.; Bolte, M.

    1999-04-01

    The crystal structures of 1,4,7,10,13,16-hexaoxa-cyclooctadecane dicyano mercury(II) monohydrate, C{sub 14}H{sub 24}HgN{sub 2}O{sub 6}{center{underscore}dot}H{sub 2}O, 1, and 2,5,8,11,18,21,24,27-octaoxa-tricyclo[26.4.0.0{sub 12,17}]-dotriconta-1(28),12,14,16,29,31-hexaene dicyano mercury(II) monohydrate, C{sub 26}H{sub 32}HgN{sub 2}O{sub 8}{center{underscore}dot}H{sub 2}O, 2, were determined: 1 crystallizes in the trigonal space group R{bar 3} with cell dimensions a = 11.7842(1) and c = 12.0316(1) {angstrom}. 2 crystallizes in the monoclinic space group P2{sub 1}/c with cell dimensions a = 11.156(3) {angstrom}, b = 8.417(2), c = 30.901(8) {angstrom}, and {beta} = 93.279{degree}. In spite of the different cyclic systems, similar complexes are formed where the Hg atom is coordinated by two CN groups and six oxygen atoms of the crown ether. The structure of 1 is isostructural with the crystal structures of 18C6-HgCl{sub 2}, 18C6-CdBr{sub 2}, 18C6-Sr(BH{sub 4}){sub 2}, and 18C6-Ba(BH{sub 4}){sub 2}. Furthermore, 1 is very similar to other 18C6-HgX{sub 2} complexes.

  19. 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. PMID:23570540

  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. Experimental challenge to nucleosynthesis in core-collapse supernovae - Very early epoch of type II SNe -

    NASA Astrophysics Data System (ADS)

    Kubono, S.; Binh, Dam N.; Hayakawa, S.; Hashimoto, T.; Kahl, D. M.; Yamaguchi, H.; Wakabayashi, Y.; Teranishi, T.; Iwasa, N.; Komatsubara, T.; Kato, S.; Chen, A.; Cherubini, S.; Choi, S. H.; Hahn, I. S.; He, J. J.; Khiem, Le H.; Lee, C. S.; Kwon, Y. K.; Wanajo, S.; Janka, H.-T.

    2013-05-01

    Nucleosynthesis is one of the keys in studying the mechanism of core-collapse supernovae, which is an interesting challenge for modern science. The νp-process, which is similar to an explosive hydrogen burning process, has been proposed as the most probable process in the very early epoch of type II supernovae. Here, we discuss our experimental efforts for the νp-process, the first extensive direct measurements of the (α,p) reactions on bottle-neck proto-rich nuclei in light mass regions. Other challenges for the νp-process study are also discussed.

  2. Chains of Dense Cores in the Taurus L1495/B213 Complex

    NASA Astrophysics Data System (ADS)

    Tafalla, Mario; Hacar, Alvaro

    2014-07-01

    We study the formation of dense cores in the filamentary L1495/B213 region of Taurus. Observations of its C18O emission show that what appears as a single 10pc-long filament in optical and continuum images is in fact a complex web of smaller filamentary structures that we call fibers. These fibers are typically 0.5~pc long and velocity coherent, and seem to have decoupled from the turbulent velocity field of the large-scale cloud. Fibers appear as the true parent structures of the cores, but only a small subset of them seem able to form cores ("fertile fibers") while the rest remain sterile. The fertile-sterile dychotomy of fibers is striking, since sterile fibers do not form cores but fertile fibers form three cores on average. As a result, most cores in the L1495/B213 region are part of linear groups or chains that have a typical core spacing of 0.1pc. Our observations and analysis suggest that core formation out of a large-scale filament is a two-step process that involves first the dissipation of turbulence via shock interaction and then the fragmentation of those disspated structures that exceed the mass per unit length limit of gravitational instability.

  3. 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.

  4. 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.

  5. A lariat-functionalized copper(II) diimine-dioxime complex.

    PubMed

    Kiani, Salma; Staples, Richard J; Packard, Alan B

    2002-12-01

    The dimeric title copper(II) complex, diaqua-1kappaO,2kappaO-bis[3,9-dimethyl-6-(2-pyridylmethyl)-4,8-diazaundeca-3,8-diene-2,10-dione dioximato(1-)]-1k(4)N(2),N(4),N(8),N(10);1:2kappa(5)O(2):N(2),N(4),N(8),N(10)-dicopper(II) diperchlorate, [Cu(2)(C(17)H(24)N(5)O(2))(2)](ClO(4))(2), crystallizes with one Cu atom in a square-pyramidal environment and the other Cu atom displaying a distorted octahedral coordination. In each case, the four N atoms in the core of the ligand (two imine and two oxime N atoms) form the base of the pyramid, with a water molecule at an apex. The two parts of the dimer are linked by an interaction [2.869 (2) A] between one of the Cu atoms and one of the oxime O atoms coordinated to the second Cu atom, and also by a hydrogen bond between the apical water molecule on the second Cu atom and the pyridyl N atom from the coordination sphere of the first Cu atom. The pyridyl N atoms of the lariat arms are not coordinated to either of the Cu atoms. Thus, this potentially pentadentate ligand is only tetradentate when coordinated to Cu(II). PMID:12466608

  6. A lariat-functionalized copper(II) diimine—dioxime complex

    PubMed Central

    Kiani, Salma; Staples, Richard J.; Packard, Alan B.

    2013-01-01

    The dimeric title copper(II) complex, diaqua-1κO,2κO-bis[3,9-dimethyl-6-(2-pyridylmethyl)-4,8-diazaundeca-3,8-diene-2,10-dione dioximato(1–)]-1k4N2,N4,N8,N10;1:2κ5O2:N2,-N4,N8,N10-dicopper(II) diperchlorate, [Cu2(C17H24N5O2)2]-(ClO4)2, crystallizes with one Cu atom in a square-pyramidal environment and the other Cu atom displaying a distorted octahedral coordination. In each case, the four N atoms in the core of the ligand (two imine and two oxime N atoms) form the base of the pyramid, with a water molecule at an apex. The two parts of the dimer are linked by an interaction [2.869 (2) Å] between one of the Cu atoms and one of the oxime O atoms coordinated to the second Cu atom, and also by a hydrogen bond between the apical water molecule on the second Cu atom and the pyridyl N atom from the coordination sphere of the first Cu atom. The pyridyl N atoms of the lariat arms are not coordinated to either of the Cu atoms. Thus, this potentially pentadentate ligand is only tetradentate when coordinated to CuII. PMID:12466608

  7. 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.

  8. 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.

  9. The antimicrobial and antibiofilm activities of copper(II) complexes.

    PubMed

    Beeton, Michael L; Aldrich-Wright, Janice R; Bolhuis, Albert

    2014-11-01

    Biofilm-related bacterial infections pose a significant problem, as they are generally more tolerant to antibiotics and the immune system. Development of novel compounds with antibiofilm activity is therefore paramount. In this study we have analysed metal complexes of the general structure [M(IL)(AL)](2+) (where IL represents functionalised 1,10-phenanthrolines and AL represents 1S,2S- or 1R,2R-diaminocyclohexane) and [Cu(IL)3](2+). Antimicrobial activity was tested on a number of bacterial strains, showing that copper(II) compounds were active against both Gram-positive and Gram-negative bacteria, albeit that activity was generally higher for the former. The antibiofilm activity was then determined against a clinical isolate of meticillin-resistant Staphylococcus aureus (MRSA). Strikingly, the copper complexes tested showed significant activity against biofilms, and were better in the removal of biofilms than vancomycin, an antibiotic that is currently used in the treatment of MRSA infections. PMID:25124857

  10. Local structure analysis of some Cu(II) theophylline complexes

    NASA Astrophysics Data System (ADS)

    David, L.; Cozar, O.; Forizs, E.; Cr ăciun, C.; Ristoiu, D.; B ălan, C.

    1999-10-01

    The CuT 2L 2·2H 2O complexes [T=Theophylline (1,3-dimethylxanthine); L=NH 3, n-propylamine (npa), 2-aminoethanol (ae)] were prepared and investigated by ESR spectroscopy. Powder ESR spectrum of CuT 2(NH 3) 2·2H 2O is axial ( g||=2.255, g⊥=2.059). ESR spectrum of CuT 2(npa) 2·2H 2O with ( g||=2.299, g⊥=2.081) is a superposition of one axial ( g||=2.299, g⊥=2.073) and one isotropic component ( g0≈2.089), in the same amount. The axial spectra of the former complexes are due to a static Jahn-Teller effect ( EJT≈2880 cm -1). ESR spectrum of CuT 2(ae) 2·2H 2O is orthorhombic ( g1c=2.199, g2c=2.095, g3c=2.037). The local symmetries around the Cu(II) ions remain unchanged by DMF solvating, by adsorbing these solutions on NaY zeolite or by lowering the temperature.

  11. Structures and stabilities of Cd(II) and Cd(II)-phthalate complexes at the goethite/water interface

    NASA Astrophysics Data System (ADS)

    Boily, Jean-François; Sjöberg, Staffan; Persson, Per

    2005-07-01

    The complexation of Cd(II) and Cd(II)-phthalate at the goethite/water interface were investigated by EXAFS and IR spectroscopy, by batch adsorption experiments and by potentiometric titrations at 298.15 K. The EXAFS spectra showed Cd(II) to form only inner-sphere corner-sharing complexes with the goethite surface sites in the presence and absence of phthalate. EXAFS spectra also showed the presence of Cd(II)-chloride complexes in 0.1 mol/L NaCl. IR spectra also showed phthalate to form (1) an inner-sphere complex with adsorbed corner-sharing Cd(II) surface complexes in the pH 3.5 to 9.5 and (2) an outer-sphere complex with the same type of corner-sharing Cd(II) complex however at pH > 6, in addition to the inner- and outer-sphere complexes of phthalate reported in a previous study. The potentiometric titration and the batch adsorption data were used to constrain the formation constants of the different Cd(II)-phthalate surface complexes on the dominant {110} and the {001} planes of the goethite. The models were carried out with the Charge Distribution Multisite Complexation model coupled to the Three Plane Model and can predict the molecular-scale speciation of cadmium and phthalate in the presence of goethite. Cd(II) adsorption models calibrated on a 90 m 2/g goethite also could accurately predict experimental data for a 37 m 2/g goethite of slightly different basic charging properties.

  12. Structures and stabilities of Cd(II) and Cd(II)-phthalate complexes at the goethite/water interface

    SciTech Connect

    Boily, Jean F.; Sjoberg, Staffan; Persson, Per

    2005-01-01

    The complexation of Cd(II) and Cd(II)-phthalate at the goethite/water interface were investigated by EXAFS and IR spectroscopy, by batch adsorption experiments and by potentiometric titrations at 298.15 K. The EXAFS spectra showed Cd(II) to form only inner-sphere corner-sharing complexes with the goethite surface sites in the presence and absence of phthalate. EXAFS spectra also showed the presence of Cd(II)-chloride complexes in 0.1 mol/L NaCl. IR spectra also showed phthalate to form (1) an inner-sphere complex with adsorbed corner-sharing Cd(II) surface complexes in the pH 3.5 to 9.5 and (2) an outer-sphere complex with the same type of corner-sharing Cd(II) complex however at pH > 6, in addition to the inner- and outer-sphere complexes of phthalate reported in a previous study. The potentiometric titration and the batch adsorption data were used to constrain the formation constants of the different Cd(II)-phthalate surface complexes on the dominant {110} and the {001} planes of the goethite. The models were carried out with the Charge Distribution Multisite Complexation model coupled to the Three Plane Model and can predict the molecular-scale speciation of cadmium and phthalate in the presence of goethite. Cd(II) adsorption models calibrated on a 90 m2/g goethite also could accurately predict experimental data for a 37 m2/g goethite of slightly different basic charging properties.

  13. 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.

  14. Integrity of the core mitochondrial RNA-binding complex 1 is vital for trypanosome RNA editing.

    PubMed

    Huang, Zhenqiu; Faktorová, Drahomíra; Křížová, Adéla; Kafková, Lucie; Read, Laurie K; Lukeš, Julius; Hashimi, Hassan

    2015-12-01

    Trypanosoma brucei is the causative agent of the human and veterinarian diseases African sleeping sickness and nagana. A majority of its mitochondrial-encoded transcripts undergo RNA editing, an essential process of post-transcriptional uridine insertion and deletion to produce translatable mRNA. Besides the well-characterized RNA editing core complex, the mitochondrial RNA-binding 1 (MRB1) complex is one of the key players. It comprises a core complex of about six proteins, guide RNA-associated proteins (GAPs) 1/2, which form a heterotetramer that binds and stabilizes gRNAs, plus MRB5390, MRB3010, and MRB11870, which play roles in initial stages of RNA editing, presumably guided by the first gRNA:mRNA duplex in the case of the latter two proteins. To better understand all functions of the MRB1 complex, we performed a functional analysis of the MRB8620 core subunit, the only one not characterized so far. Here we show that MRB8620 plays a role in RNA editing in both procyclic and bloodstream stages of T. brucei, which reside in the tsetse fly vector and mammalian circulatory system, respectively. While RNAi silencing of MRB8620 does not affect procyclic T. brucei fitness when grown in glucose-containing media, it is somewhat compromised in cells grown in the absence of this carbon source. MRB8620 is crucial for integrity of the MRB1 core, such as its association with GAP1/2, which presumably acts to deliver gRNAs to this complex. In contrast, GAP1/2 is not required for the fabrication of the MRB1 core. Disruption of the MRB1 core assembly is followed by the accumulation of mRNAs associated with GAP1/2. PMID:26447184

  15. Solution Structure and Characterisation of the Human Pyruvate Dehydrogenase Complex Core Assembly

    PubMed Central

    Vijayakrishnan, S.; Kelly, S.M.; Gilbert, R.J.C.; Callow, P.; Bhella, D.; Forsyth, T.; Lindsay, J.G.; Byron, O.

    2010-01-01

    Mammalian pyruvate dehydrogenase complex (PDC) is a key multi-enzyme assembly that is responsible for glucose homeostasis maintenance and conversion of pyruvate into acetyl-CoA. It comprises a central pentagonal dodecahedral core consisting of two subunit types (E2 and E3BP) to which peripheral enzymes (E1 and E3) bind tightly but non-covalently. Currently, there are two conflicting models of PDC (E2 + E3BP) core organisation: the ‘addition’ model (60 + 12) and the ‘substitution’ model (48 + 12). Here we present the first ever low-resolution structures of human recombinant full-length PDC core (rE2/E3BP), truncated PDC core (tE2/E3BP) and native bovine heart PDC core (bE2/E3BP) obtained by small-angle X-ray scattering and small-angle neutron scattering. These structures, corroborated by negative-stain and cryo electron microscopy data, clearly reveal open pentagonal core faces, favouring the ‘substitution’ model of core organisation. The native and recombinant core structures are all similar to the truncated bacterial E2 core crystal structure obtained previously. Cryo-electron microscopy reconstructions of rE2/E3BP and rE2/E3BP:E3 directly confirm that the core has open pentagonal faces, agree with scattering-derived models and show density extending outwards from their surfaces, which is much more structurally ordered in the presence of E3. Additionally, analytical ultracentrifugation characterisation of rE2/E3BP, rE2 (full-length recombinant E2-only) and tE2/E3BP supports the substitution model. Superimposition of the small-angle neutron scattering tE2/E3BP and truncated bacterial E2 crystal structures demonstrates conservation of the overall pentagonal dodecahedral morphology, despite evolutionary diversity. In addition, unfolding studies using circular dichroism and tryptophan fluorescence spectroscopy show that the rE2/E3BP is less stable than its rE2 counterpart, indicative of a role for E3BP in core destabilisation. The architectural

  16. 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.

  17. 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.

  18. Thermal studies and vibrational analyses of m-methylaniline complexes of Zn(II), Cd(II) and Hg(II) bromides

    NASA Astrophysics Data System (ADS)

    Golcuk, K.; Altun, A.; Kumru, M.

    2003-06-01

    The complexes having the MBr2L2 (M: Zn, Cd and Hg; L: m-methylaniline) formulae have been prepared and characterized by their elemental analyses, thermogravimetric analyses, IR and Raman spectral studies. IR and Raman bands of the complexes have been assigned as compared with the free ligand. Coordination effects on the internal modes of m-methylaniline have been discussed. Vibrational spectra propose that the [ZnBr2(mMA)2] complex is in a tetrahedral environment around Zn(II) ion with C2v symmetry whereas Cd(II) and Hg(II) complexes have 5-coordinate polymeric bromide bridged structures.

  19. Fault strength and the formation of rider blocks and domes in continental and oceanic core complexes

    NASA Astrophysics Data System (ADS)

    Buck, W. Roger; Choi, Eunseo

    2014-05-01

    Core complexes are places where slip of normal sense 'detachment' faults exhumes rocks from more than 10 km depth. We first present 2D cross-sectional model results showing that core complex detachment faults are strong and that their strength has to be in a narrow range to allow kilometer scale "rider blocks" to develop. Previous numerical simulations of lithospheric extension produced the large offset, core complex-forming, normal faults only when the faults were weaker than a given threshold. High-resolution simulations are needed to resolve rider blocks and they only form when the faults are stronger than a given level. A narrow range of fault weakening, relative to intact surrounding rock, allows for a consecutive series of rider blocks to emerge in a core complex-like geometry. Rider blocks develop when the dominant form of weakening is by reduction of fault cohesion while faults that weaken primarily by friction reduction do not form distinct rider blocks. The term 'core' refers to the oval region of rocks exhumed from depth and surrounded by rocks formed at shallower depths. Cores are typically 10-15 km wide and longer in the extension direction. 2 and 3D numerical and analog models are used to show that the cores could form as a result of 'continuous casting' of warm, ductile lower plate rocks pulled up against a cold upper plate (Spencer, 1999). Spencer (1999) considered undulations in the surface of a brittle plate while here we consider how a both the surface and base of the plate can be "cast" with a nearly parallel shape. Ridges can locally migrate in time and may do so in response to along-axis variations in the magmatic accommodation of plate separation. We suggest that the core geometry is formed by along strike variations in the horizontal position of the detachment boundary. Long wavelength (compared to the brittle layer thickness) horizontal undulations in the position of the detachment can produce parallel undulations in both the surface and

  20. Flexible Stoichiometry and Asymmetry of the PIDDosome Core Complex by Heteronuclear NMR Spectroscopy and Mass Spectrometry

    PubMed Central

    Nematollahi, Lily A.; Garza-Garcia, Acely; Bechara, Chérine; Esposito, Diego; Morgner, Nina; Robinson, Carol V.; Driscoll, Paul C.

    2015-01-01

    Homotypic death domain (DD)–DD interactions are important in the assembly of oligomeric signaling complexes such as the PIDDosome that acts as a platform for activation of caspase-2-dependent apoptotic signaling. The structure of the PIDDosome core complex exhibits an asymmetric three-layered arrangement containing five PIDD-DDs in one layer, five RAIDD-DDs in a second layer and an additional two RAIDD-DDs. We addressed complex formation between PIDD-DD and RAIDD-DD in solution using heteronuclear nuclear magnetic resonance (NMR) spectroscopy, nanoflow electrospray ionization mass spectrometry and size-exclusion chromatography with multi-angle light scattering. The DDs assemble into complexes displaying molecular masses in the range 130–158 kDa and RAIDD-DD:PIDD-DD stoichiometries of 5:5, 6:5 and 7:5. These data suggest that the crystal structure is representative of only the heaviest species in solution and that two RAIDD-DDs are loosely attached to the 5:5 core. Two-dimensional 1H,15N-NMR experiments exhibited signal loss upon complexation consistent with the formation of high-molecular-weight species. 13C-Methyl-transverse relaxation optimized spectroscopy measurements of the PIDDosome core exhibit signs of differential line broadening, cross-peak splitting and chemical shift heterogeneity that reflect the presence of non-equivalent sites at interfaces within an asymmetric complex. Experiments using a mutant RAIDD-DD that forms a monodisperse 5:5 complex with PIDD-DD show that the spectroscopic signature derives from the quasi- but non-exact equivalent environments of each DD. Since this characteristic was previously demonstrated for the complex between the DDs of CD95 and FADD, the NMR data for this system are consistent with the formation of a structure homologous to the PIDDosome core. PMID:25528640

  1. Flexible stoichiometry and asymmetry of the PIDDosome core complex by heteronuclear NMR spectroscopy and mass spectrometry.

    PubMed

    Nematollahi, Lily A; Garza-Garcia, Acely; Bechara, Chérine; Esposito, Diego; Morgner, Nina; Robinson, Carol V; Driscoll, Paul C

    2015-02-27

    Homotypic death domain (DD)-DD interactions are important in the assembly of oligomeric signaling complexes such as the PIDDosome that acts as a platform for activation of caspase-2-dependent apoptotic signaling. The structure of the PIDDosome core complex exhibits an asymmetric three-layered arrangement containing five PIDD-DDs in one layer, five RAIDD-DDs in a second layer and an additional two RAIDD-DDs. We addressed complex formation between PIDD-DD and RAIDD-DD in solution using heteronuclear nuclear magnetic resonance (NMR) spectroscopy, nanoflow electrospray ionization mass spectrometry and size-exclusion chromatography with multi-angle light scattering. The DDs assemble into complexes displaying molecular masses in the range 130-158kDa and RAIDD-DD:PIDD-DD stoichiometries of 5:5, 6:5 and 7:5. These data suggest that the crystal structure is representative of only the heaviest species in solution and that two RAIDD-DDs are loosely attached to the 5:5 core. Two-dimensional (1)H,(15)N-NMR experiments exhibited signal loss upon complexation consistent with the formation of high-molecular-weight species. (13)C-Methyl-transverse relaxation optimized spectroscopy measurements of the PIDDosome core exhibit signs of differential line broadening, cross-peak splitting and chemical shift heterogeneity that reflect the presence of non-equivalent sites at interfaces within an asymmetric complex. Experiments using a mutant RAIDD-DD that forms a monodisperse 5:5 complex with PIDD-DD show that the spectroscopic signature derives from the quasi- but non-exact equivalent environments of each DD. Since this characteristic was previously demonstrated for the complex between the DDs of CD95 and FADD, the NMR data for this system are consistent with the formation of a structure homologous to the PIDDosome core. PMID:25528640

  2. 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.

  3. A core-shell structured inorganic-organic hybrid nanocomposite for Hg(II) sensing and removal.

    PubMed

    Jiqu, Han; Qixia, Yang

    2015-10-01

    In the present paper, a core-shell structured inorganic-organic hybrid nanocomposite for Hg(II) sensing and removal was designed and fabricated, where the core was composed of superparamagnetic Fe3O4 and the shell consisted of molecular silica sieve MCM-41. A rhodamine derived probe was grafted onto the backbone of MCM-41 through a silane coupling reagent to control its loading content. This probe functionalized core-shell structure was confirmed and characterized by XRD analysis, electron microscopy images, IR spectra, thermogravimetry and N2 adsorption/desorption isotherms. It was found that the emission of this composite increased with increasing Hg(II) concentrations but was immune to other metal ions, showing good selectivity and high sensitivity towards Hg(II) ions. A linear Stern-Volmer curve was observed with short response time. In addition, this composite possessed good Hg(II)-removing and recycling performance. PMID:25978016

  4. Antiviral activity of platinum (II) and palladium (II) complexes of pyridine-2-carbaldehyde thiosemicarbazone.

    PubMed

    Varadinova, T; Kovala-Demertzi, D; Rupelieva, M; Demertzis, M; Genova, P

    2001-04-01

    A heterocyclic compound, pyridine-2-carbaldehyde thiosemicarbazone (HFoTsc), and its six metal coordinated bound complexes, three with platinum (II) and three with palladium (II), were studied for their activity against herpes simplex virus 1 (HSV-1) infection in cultured cells. According to their cytotoxicity the compounds were divided into two groups. Group I (cytotoxic compounds) included all three palladium complexes and [Pt(HFoTsc)2] Cl2, with maximum non-toxic concentration (MNC) of 1-10 micromol/l and a 50% cytotoxic concentration (CC50) of 20-100 micromol/l. Group 2 (low cytotoxic compounds) with MNC of 100 micromol/l and CC50 of 548-5820 micromol/l included compounds in the following order: [Pt(HFoTsc)2] Cl2complexes as well as [Pd(HFoTsc)2]Cl2 and [Pd(FoTsc)2] inhibited HSV- I infection following a structure-activity relationship but only [Pt(HFoTsc)2]Cl2 expressed a significant selectivity comparable to that of HFoTsc. However, [PdCl(FoTsc)] acting 48 hrs gave a higher infectious HSV-1 titer (170%) compared to control (100%, no compound). PMID:11719987

  5. 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.

  6. 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.

  7. 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…

  8. 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...

  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. 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.

  11. Synthesis and characterization of an azo dibenzoic acid Schiff base and its Ni(II), Pb(II), Zn(II) and Cd(II) complexes

    NASA Astrophysics Data System (ADS)

    Kakanejadifard, Ali; Esna-ashari, Fatemeh; Hashemi, Payman; Zabardasti, Abedin

    2013-04-01

    The new Schiff base 4,4'-(1E,1'E)-(3,3'-(1E,1'E)-(pyridine-2,6-diylbis(azan-1-yl-1-ylid ene))bis(methan-1-yl-1-ylidene)bis(4-hydroxy-3,1-phenylene))bis(diazene-2,1-diyl)dibenzoic acid (1) was prepared from the condensation reaction of 2,6-diaminopyridine with 4-((3-formyl-4-hydroxyphenyl)diazenyl)benzoic acid in methanol. The compound 1 is potentially an N, O multidentate chelating ligand which could form stable complexes with metal ions in 1:1 up to 1:3 mol ratio of metal to ligand. The 1:1 complexes of Schiff base 1 with Ni(II), Pb(II), Zn(II) and Cd(II) have been synthesized by its condensation reaction with appropriate salts of metal ions. Structures of Schiff base (1) as well as its complexes with abovementioned metal ions were characterized by elemental analysis, mass, IR, UV-vis., 1H and 13С NMR spectroscopy.

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

    NASA Astrophysics Data System (ADS)

    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.

    2016-05-01

    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.

  13. 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

  14. A curious interplay in the films of N-heterocyclic carbene Pt(II) complexes upon deposition of alkali metals.

    PubMed

    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 Pt(II) 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 Pt(II) 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 Pt(II) centre to Pt(0) 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 Pt(II) complexes for a variety of biomedical, sensing, chemical, and electronic applications. PMID:27151364

  15. Synthesis, spectroscopic characterization and biological activities of N4O2 Schiff base ligand and its metal complexes of Co(II), Ni(II), Cu(II) and Zn(II)

    NASA Astrophysics Data System (ADS)

    Al-Resayes, Saud I.; Shakir, Mohammad; Abbasi, Ambreen; Amin, Kr. Mohammad Yusuf; Lateef, Abdul

    The Schiff base ligand, bis(indoline-2-one)triethylenetetramine (L) obtained from condensation of triethylenetetramine and isatin was used to synthesize the complexes of type, [ML]Cl2 [M = Co(II), Ni(II), Cu(II) and Zn(II)]. L was characterized on the basis of the results of elemental analysis, FT-IR, 1H and 13C NMR, mass spectroscopic studies. The stoichiometry, bonding and stereochemistries of complexes were ascertained on the basis of results of elemental analysis, magnetic susceptibility values, molar conductance and various spectroscopic studies. EPR, UV-vis and magnetic moments revealed an octahedral geometry for complexes. L and its Cu(II) and Zn(II) complexes were screened for their antibacterial activity. Analgesic activity of Cu(II) and Zn(II) complexes was also tested in rats by tail flick method. Both complexes were found to possess good antibacterial and moderate analgesic activity.

  16. Stable isotope paleoaltimetry of Eocene core complexes in the North American Cordillera

    NASA Astrophysics Data System (ADS)

    Mulch, A.; Teyssier, C.; Cosca, M. A.; Chamberlain, C. P.

    2007-08-01

    The hydrogen isotope composition of Eocene muscovite in mylonitic quartzite from the Kettle and Shuswap metamorphic core complexes (Washington and British Columbia) permits estimates of paleoaltimetry of the North American Cordillera at the onset of post-collisional lithospheric extension. Coupled oxygen, hydrogen, and 40Ar/39Ar isotope data indicate that meteoric water penetrated to significant depths during normal faulting along the Columbia River Detachment bounding both Kettle and Shuswap metamorphic core complexes. Synkinematic muscovite attains δDmuscovite values as low as -135‰ and -157‰, respectively, consistent with δDwater values of -115 ± 5‰ and -135 ± 5‰. In context with stable isotope data from Eocene sedimentary basins of continental North America, these data constrain the isotopic composition of precipitation from which paleoelevation estimates can be made. Stable isotope paleoaltimetry indicates that during detachment formation (49-47 Ma), orogen-parallel variations in topography existed, and mean elevations decreased from ≥4000 m at the latitude of the Shuswap core complex to ≥3000 m in the Kettle core complex. In addition, these data indicate a net decrease in mean surface elevation by ˜1000 m since the Eocene. Our results for the Kettle core complex are consistent with paleoelevation estimates based on fossil floral physiognomy in the Eocene Republic basin (Washington), indicating that high elevations characterized not only the frontal escarpment near the crustal-scale detachment but continued into the Okanogan highlands further west. Collectively, the stable isotope, geochronological, and paleofloral data support tectonic models of high Eocene surface elevations contemporaneous with magmatism and lithospheric extension.

  17. Death Domain Assembly Mechanism Revealed by Crystal Structure of the Oligomeric PIDDosome Core Complex

    SciTech Connect

    Park,H.; Logette, E.; Raunser, S.; Cuenin, S.; Walz, T.; Tschopp, J.; Wu, H.

    2007-01-01

    Proteins of the death domain (DD) superfamily mediate assembly of oligomeric signaling complexes for the activation of caspases and kinases via unknown mechanisms. Here we report the crystal structure of the PIDD DD and RAIDD DD complex, which forms the core of the caspase-2-activating complex PIDDosome. Although RAIDD DD and PIDD DD are monomers, they assemble into a complex that comprises seven RAIDD DDs and five PIDD DDs. Despite the use of an asymmetric assembly mechanism, all DDs in the complex are in quasi-equivalent environments. The structure provided eight unique asymmetric interfaces, which can be classified into three types. These three types of interactions together cover a majority of the DD surface. Mutagenesis on almost all interfaces leads to disruption of the assembly, resulting in defective caspase-2 activation. The three types of interactions may represent most, if not all, modes of interactions in the DD superfamily for assembling complexes of different stoichiometry.

  18. Death Domain Assembly Mechanism Revealed by Crystal Structure of the Oligomeric PIDDosome Core Complex

    PubMed Central

    Park, Hyun Ho; Logette, Emmanuelle; Raunser, Stefan; Cuenin, Solange; Walz, Thomas; Tschopp, Jurg; Wu, Hao

    2010-01-01

    SUMMARY Proteins of the death domain (DD) superfamily mediate assembly of oligomeric signaling complexes for the activation of caspases and kinases via unknown mechanisms. Here we report the crystal structure of the PIDD DD and RAIDD DD complex, which forms the core of the caspase-2 activating complex PIDDosome. While RAIDD DD and PIDD DD are monomers, they assemble into a complex that comprises seven RAIDD DDs and five PIDD DDs. Despite the use of an asymmetric assembly mechanism, all DDs in the complex are in quasi-equivalent environments. The structure provided eight unique asymmetric interfaces, which can be classified into three types. These three types of interactions together cover a majority of the DD surface. Mutagenesis on almost all interfaces leads to disruption of the assembly resulting in defective caspase-2 activation. The three types of interactions may represent most, if not all, modes of interactions in the DD superfamily for assembling complexes of different stoichiometry. PMID:17289572

  19. 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.

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

    PubMed

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

    2015-01-25

    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 (1)H and (13)C 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. PMID:25064500

  1. Water masers embedded in ultracompact H II regions: The W 75N cloud core

    NASA Astrophysics Data System (ADS)

    Hunter, T. R.; Taylor, G. B.; Felli, M.; Tofani, G.

    1994-04-01

    We present radio observations of the W 75N star forming region consisting of:(1) high-resolution Very Large Array (VLA) radio continuum and H2O maser maps, (2) CSO molecular maps in the CS and CO lines, (3) results from a six-year monitoring campaign of the H2O maser emission with the 32-m Medicina telescope. Using the VLA in A-configuration, we find that the 22 GHz H2O maser spots in W 75N spatially coincide with very weak, small diameter (less than 1 sec) radio continuum sources at the center of the dense molecular cloud core. The very high optical obscuration (Ar greater than or equal 90 mag), the high total luminosity of the source and the high electron density suggest that in W 75N we are witnessing the first appearance of an ultracompact H II region (UCH II) produced by an early type star still deeply embedded in the progenitor molecular cloud. The H2O maser - UCH II association may last only for the short time (approximately 103 y) needed by the H II to expand out to the distance where masers are formed. Both the H2O and OH masers as well as the continuum sources extend a few seconds of arc along a roughly N-S line, matching the extension of the core evident in the CS J = 7 goes to 6 map and nearly perpendicular to the axis of the molecular outflow. As traced by the CO J = 3 goes to 2 transition, the origin of the outflow lies at the position of the UCH IIs, suggesting that they are associated with the powering source. The H2O spectrum extends over approximately 30 km/s, with many distinct velocity components, part of which can be unambiguously identified with individual spatial components of the VLA H2O map. The variability of the H2O emission of each velocity component is very high, with time scales of the order of a few years and dynamic range almost up to two orders of magnitude. For the bluest velocity component, well isolated in the velocity and space domains, there is evidence of a continuous velocity drift of approximately 4 km/s over 2 years. The

  2. Metal (II) Complexes Derived from Naphthofuran-2-carbohydrazide and Diacetylmonoxime Schiff Base: Synthesis, Spectroscopic, Electrochemical, and Biological Investigation

    PubMed Central

    Sumathi, R. B.; Halli, M. B.

    2014-01-01

    A new Schiff base and a new series of Co(II), Ni(II), Cu(II), Cd(II), and Hg(II) complexes were synthesized by the condensation of naphthofuran-2-carbohydrazide and diacetylmonoxime. Metal complexes of the Schiff base were prepared from their chloride salts of Co(II), Ni(II), Cu(II), Cd(II), and Hg(II) in ethanol. The ligand along with its metal complexes have been characterized on the basis of analytical data, IR, electronic, mass, 1HNMR, ESR spectral data, thermal studies, magnetic susceptibility, and molar conductance measurements. The nonelectrolytic behaviour of the complexes was assessed from the measured low conductance data. The elemental analysis of the complexes confirm the stoichiometry of the type CuL2Cl2 and MLCl2 where M = Ni(II), Co(II), Cd(II), and Hg(II) and L = Schiff base. The redox property of the Cu(II) complex was investigated by electrochemical method using cyclic voltammetry. In the light of these results, Co(II), Ni(II), and Cu(II) complexes are assigned octahedral geometry, Cd(II), and Hg(II) complexes tetrahedral geometry. In order to evaluate the effect of metal ions upon chelation, both the ligand and its metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleaving capacity of all the complexes was analysed by agarose gel electrophoresis method. PMID:24592203

  3. Vibrational and electronic spectroscopy of electronically exicted polychromophoric ruthenium(II) complexes

    SciTech Connect

    Bignozzi, C.A.; Argazzi, R.; Chiorboli, C.; Scandola, F. ); Dyer, R.B. ); Schoonover, J.R.; Meyer, T.J )

    1994-04-13

    The metal to ligand charge-transfer excited states of the polychromophoric complexes [(NC)-(bpy)[sub 2]Ru[sup II](CN)Ru[sup II](bpy)[sub 2](CN)][sup +], [(NC)(bpy)[sub 2]Ru[sup II](CN)Ru[sup II](phen)[sub 2](CN)][sup +], [(NC)(phen)[sub 2]Ru[sup II](CN)Ru[sup II](bpy)[sub 2](CN)][sup +], [(NC)(bpy)[sub 2]Ru[sup II](CN)Ru[sup II](bpy)[sub 2](NC)Ru[sup II](bpy)[sub 2](CN)][sup 2+], and [NC(bpy)[sub 2]Ru[sup II](CN)Ru[sup II](dcb)[sub 2](NC)Ru(bpy)[sub 2](CN)][sup 2[minus

  4. 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.

  5. New Heteroleptic Copper(II) Complexes as MOCVD Precursors

    NASA Astrophysics Data System (ADS)

    Krisyuk, V. V.; Sysoev, S. V.; Rumyantsev, Y. M.; Prokhorova, S. A.; Maximovskiy, E. V.; Kosinova, M. L.; Igumenov, I. K.

    New volatile heteroleptic copper(II) complexes having beta-ketoiminate (O,N) and diketonate (O,O) ligands in one molecule were tested as precursors for LPCVD of copper films. Saturated vapor pressure was measured and compared for new compounds Cu(ki)(hfa) and Cu(dpk)(hfa), where ki = pentane-2-imino-4-onato, hfa = 1,1,1,5,5,5-hexafluoro-pentane- 2,4-dionato, dpk= 2,2,6,6-tetramethyl-3-iminoheptane-5-onato. The precursors are air stable and non hygroscopic compounds with long shelf life. It was demonstrated that copper metal films can be selectively deposited on metallic surfaces in the presence of hydrogen as a gas-reactant at temperatures of 250, 300, 350 °C and pressure of 20 Torr. Si(100), SiO2 (melted quartz), stainless steel, and Cu, Al, RuO2, Ru and Ta sublayers on Si(100) were tested as substrate materials. Deposited films were analyzed and characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM).

  6. Structural Preferences in Phosphanylthiolato Platinum(II) Complexes

    PubMed Central

    Duran, Josep; Real, Julio; Benet‐Buchholz, Jordi; Solà, Miquel

    2016-01-01

    Abstract Invited for this month's cover picture are the groups of Prof. Alfonso Polo and Dr. Albert Poater at the Universitat de Girona, as well as their collaborators from the Universitat Autònoma de Barcelona and the Institute of Chemical Research of Catalonia. The cover picture shows phosphanylthiolate ligand coordination on a platinum(II) center to give only the bischelate cis ‐P,P isomer when the ligand/Pt ratio is 2, whereas a trinuclear unexpected complex is achieved with a ligand/Pt ratio of 1. Here, the synthesis and structural determination is combined with density functional theory (DFT) calculations to rationalize the reaction mechanistically and through conceptual DFT. The exciting point of this study is that it opens the door to test new experimental pathways to monitor the preferred cis or trans arrangement of bidentate ligands to platinum. (Legend: H‐white, C‐black, P‐purple, S‐yellow, Cl‐green, Pt‐blue.) For more details, see the Full Paper on p. 51 ff. PMID:27308218

  7. 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. PMID:24037457

  8. Reactions of Pd(II) and Pt(II) Complexes With Tetraethylthiouram Disulfide

    PubMed Central

    Cervantes, G.; Molins, E.; Miravitlles, C.

    1997-01-01

    The reactions of tetraethylthiouram disulfide (DTS), an inhibitor of the nephrotoxicity of Pt(II) drugs, an efficient agent in the treatment of chronic alcoholism, in the treatment of HIV infections, AIDS and heavy metal toxicity, and a fungicide and herbicide, with K2[PtCl4], in ratio 1:1 and 1:2, gave the compounds [PtCl2DTS] and [Pt(S2CNEt2)2] respectively. The reaction of the complexes K2[PdCl4], Pd(AcO)2 and [PdCl2(PhCN)2], where PhCN = Benzonitrile, with tetraethylthiouram disulfide in ratio 1:1 or 1:2, yielded orange crystals identified as [Pd(S2CNEt2)2]. The crystals were suitable for study by X-ray diffraction. The -S-S- bridge in the tetraethylthiouram disulfude molecule was broken and the two molecules of the thiocarbamate derivative were bound to the Pd(II) by the equivalents sulfur atoms. All the compounds were characterized by IR, 1H and 13C NMR spectroscopies. PMID:18475812

  9. Synthesis, magnetic, thermal and structural properties of Co(II), Ni(II) and Cu(II) complexes containing isophthalato ligands

    NASA Astrophysics Data System (ADS)

    Rogan, Jelena; Poleti, Dejan; Karanović, Ljiljana; Jagličić, Zvonko

    2011-01-01

    A series of novel ternary Co(II), Ni(II) and Cu(II) complexes containing 2,2'-dipyridylamine (dipya), 2,2'-bipyridine (bipy), and 1,10-phenanthroline (phen), as aromatic diamine ligands, and dianion of isophthalic acid (ipht) have been prepared by ligand exchange reactions from diluted H 2O/EtOH solutions. The complexes were characterized by elemental analysis, IR spectroscopy, magnetic susceptibility measurements and TG and DSC analysis. Three complexes, Cu(dipya)(ipht)·H 2O ( 1), Co(dipya)(ipht)·2H 2O ( 2) and Cu(ipht)(phen)·2H 2O ( 5) are polymeric with bis-monodentate ipht, while the other two complexes M(bipy)(ipht)·4H 2O, M dbnd Co(II) ( 3) and Ni(II) ( 4), contain ipht as a counter ion. All Co(II) and Ni(II) complexes are (pseudo)octahedral, while Cu(II) complexes have square-pyramidal or distorted octahedral geometry. The variable temperature magnetic susceptibility measurements showed very weak antiferromagnetic behaviour for all complexes. Dehydration processes, decomposition mechanisms and thermal stability of 1- 5 are assumed. One complex from the above series, [Ni(bipy)(H 2O) 4](ipht) ( 4), and one additional complex, [Co(bipy)(ipht)] n ( 6), are obtained as single-crystals and their structures are determined from X-ray diffraction data. In both structures M(II) centers are in deformed octahedral environment and they are linked by hemi-ipht ligands ( 4) and two different bridging ipht ligands ( 6). Three-dimensional networks in 4 and 6 are governed by strong noncovalent interactions. The cations and ipht anions in 4 are connected by hydrogen bonds building double layers parallel to ab-plane that are further packed by π- π interactions. In 6 double chains extending along b-axis are strengthened by interchain π- π interactions constructing a three-dimensional framework.

  10. DNA binding and topoisomerase II inhibitory activity of water-soluble ruthenium(II) and rhodium(III) complexes.

    PubMed

    Singh, Sanjay Kumar; Joshi, Shweta; Singh, Alok Ranjan; Saxena, Jitendra Kumar; Pandey, Daya Shankar

    2007-12-10

    Water-soluble piano-stool arene ruthenium complexes based on 1-(4-cyanophenyl)imidazole (CPI) and 4-cyanopyridine (CNPy) with the formulas [(eta6-arene)RuCl2(L)] (L = CPI, eta6-arene = benzene (1), p-cymene (2), hexamethylbenzene (3); L = CNPy, eta6-arene = benzene (4), p-cymene (5), hexamethylbenzene (6)) have been prepared by our earlier methods. The molecular structure of [(eta6-C6Me6)RuCl2(CNPy)] (6) has been determined crystallographically. Analogous rhodium(III) complex [(eta5-C5Me5)RhCl2(CPI)] (7) has also been prepared and characterized. DNA interaction with the arene ruthenium complexes and the rhodium complex has been examined by spectroscopic and gel mobility shift assay; condensation of DNA and B-->Z transition have also been described. Arene ruthenium(II) and EPh3 (E = P, As)-containing arene ruthenium(II) complexes exhibited strong binding behavior, however, rhodium(III) complexes were found to be Topo II inhibitors with an inhibition percentage of 70% (7) and 30% (7a). Furthermore, arene ruthenium complexes containing polypyridyl ligands also act as mild Topo II inhibitors (10%, 3c and 40%, 3d) in contrast to their precursor complexes. Complexes 4-6 also show significant inhibition of beta-hematin/hemozoin formation activity. PMID:18001110

  11. Template synthesis and physico-chemical characterization of 14-membered tetraimine macrocyclic complexes, [MLX 2] [M = Co(II), Ni(II), Cu(II) and Zn(II)]. DNA binding study on [CoLCl 2] complex

    NASA Astrophysics Data System (ADS)

    Firdaus, Farha; Fatma, Kaneez; Azam, Mohammad; Khan, Shahper N.; Khan, Asad U.; Shakir, Mohammad

    2009-04-01

    The template condensation reaction between glyoxal and 1,8-diaminonaphthalene resulted a few novel mononuclear 14-membered tetraimine macrocyclic complexes of the type, [MLX 2] [M = Co(II), Ni(II), Cu(II) and Zn(II), for X = Cl or NO 3]. The stoichiometry and the nature of the complexes have been deduced from the results of elemental analyses and conductance data. The formation of macrocyclic framework has been inferred from the appearance of imine υ(C dbnd N) and υ(M sbnd N) band in IR spectra and the resonance signals observed in 1H and 13C-NMR spectra. However, the overall geometry of the complexes has been assigned on the positions of bands in electronic spectra and magnetic moment data. The distortion in Cu(II) complexes has been deduced on EPR data. The thermal behavior of these complexes has been studied by TGA analysis. Absorption and circular dichroism studies on the complex proved a significant binding to calf thymus DNA.

  12. 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.

  13. 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.

    PubMed

    El-Boraey, Hanaa A

    2012-11-01

    Novel eight Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes with [N(4)] 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 d(x2-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 (IC(50)=25.6 and 41 μM) against human breast cancer cell line MCF-7 and human hepatocarcinoma HEPG2 cell line. PMID:22765944

  14. Quinoline-2-carboxaldehyde thiosemicarbazones and their Cu(II) and Ni(II) complexes as topoisomerase IIa inhibitors.

    PubMed

    Bisceglie, Franco; Musiari, Anastasia; Pinelli, Silvana; Alinovi, Rossella; Menozzi, Ilaria; Polverini, Eugenia; Tarasconi, Pieralberto; Tavone, Matteo; Pelosi, Giorgio

    2015-11-01

    A series of quinoline-2-carboxaldehyde thiosemicarbazones and their copper(II) and nickel(II) complexes were synthesized and characterized. In all complexes the ligands are in the E configuration with respect to the imino bond and behave as terdentate. The copper(II) complexes form square planar derivatives with one molecule of terdentate ligand and chloride ion. A further non-coordinated chloride ion compensates the overall charge. Nickel(II) ions form instead octahedral complexes with two ligands for each metal ion, independently from the stoichiometric metal:ligand ratio used in the synthesis. Ligands and complexes were tested for their antiproliferative properties on histiocytic lymphoma cell line U937. Copper(II) derivatives are systematically more active than the ligands and the nickel complexes. All copper derivatives result in inhibiting topoisomerase IIa in vitro. Computational methods were used to propose a model to explain the different extent of inhibition presented by these compounds. The positive charge of the dissociated form of the copper complexes may play a key role in their action. PMID:26335598

  15. 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. PMID:16854616

  16. 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

  17. Bismuth– and lead–texaphyrin complexes: towards potential α-core emitters for radiotherapy†

    PubMed Central

    Preihs, Christian; Arambula, Jonathan F.; Lynch, Vincent M.; Siddik, Zahid H.

    2011-01-01

    Lead(II)–texaphyrins and the first discrete binuclear μ–oxo bismuth(III)–texaphyrin are reported. The latter was characterized via single crystal X-ray diffraction analysis. Cell proliferation assays using the A2780 ovarian cancer cell line were used to determine the cytotoxicity of the complexes. PMID:20922235

  18. 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

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

    PubMed Central

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

    2015-01-01

    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. PMID:26430909

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  1. G-quadruplex vs. duplex-DNA binding of nickel(II) and zinc(II) Schiff base complexes.

    PubMed

    Bonsignore, Riccardo; Terenzi, Alessio; Spinello, Angelo; Martorana, Annamaria; Lauria, Antonino; Almerico, Anna Maria; Keppler, Bernhard K; Barone, Giampaolo

    2016-08-01

    Novel nickel(II) (1) and zinc(II) (2) complexes of a Salen-like ligand, carrying a pyrimidine ring on the N,N' bridge, were synthesized and characterized. Their interaction with duplex and G-quadruplex DNA was investigated in aqueous solution through UV-visible absorption, circular dichroism and viscometry measurements. The results obtained point out that, while the zinc(II) complex does not interact with both duplex and G-quadruplex DNA, the nickel(II) complex 1 binds preferentially to G-quadruplex respect to duplex-DNA, with values of the DNA-binding constants, Kb, 2.6×10(5)M(-1) and 3.5×10(4)M(-1), respectively. Molecular dynamics simulations provided an atomic level model of the top-stacking binding occurring between 1 and hTelo (a 22-mer sequence oligonucleotide) in G-quadruplex conformation. PMID:27230387

  2. 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.

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

    PubMed

    Chandra, Sulekh; Vandana

    2014-08-14

    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, (1)H 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. PMID:24747857

  4. 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. PMID:27514916

  5. 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

  6. 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

  7. Human carbonic anhydrase II as a host for piano-stool complexes bearing a sulfonamide anchor.

    PubMed

    Monnard, Fabien W; Heinisch, Tillmann; Nogueira, Elisa S; Schirmer, Tilman; Ward, Thomas R

    2011-08-01

    d(6)-piano-stool complexes bearing an arylsulfonamide anchor display sub-micromolar affinity towards human Carbonic Anhydrase II (hCA II). The 1.3 Å resolution X-ray crystal structure of [(η(6)-C(6)Me(6))Ru(bispy 3)Cl](+)⊂ hCA II highlights the nature of the host-guest interactions. PMID:21706094

  8. Mononuclear nickel(II)-superoxo and nickel(III)-peroxo complexes bearing a common macrocyclic TMC ligand.

    PubMed

    Cho, Jaeheung; Kang, Hye Yeon; Liu, Lei V; Sarangi, Ritimukta; Solomon, Edward I; Nam, Wonwoo

    2013-04-01

    Mononuclear metal-dioxygen adducts, such as metal-superoxo and -peroxo species, are generated as key intermediates in the catalytic cycles of dioxygen activation by heme and non-heme metalloenzymes. We have shown recently that the geometric and electronic structure of the Ni-O2 core in [Ni(n-TMC)(O2)](+) (n = 12 and 14) varies depending on the ring size of the supporting TMC ligand. In this study, mononuclear Ni(II)-superoxo and Ni(III)-peroxo complexes bearing a common macrocylic 13-TMC ligand, such as [Ni(II)(13-TMC)(O2)](+) and [Ni(III)(13-TMC)(O2)](+), were synthesized in the reaction of [Ni(II)(13-TMC)(CH3CN)](2+) and H2O2 in the presence of tetramethylammonium hydroxide (TMAH) and triethylamine (TEA), respectively. The Ni(II)-superoxo and Ni(III)-peroxo complexes bearing the common 13-TMC ligand were successfully characterized by various spectroscopic methods, X-ray crystallography, and DFT calculations. Based on the combined experimental and theoretical studies, we conclude that the superoxo ligand in [Ni(II)(13-TMC)(O2)](+) is bound in an end-on fashion to the nickel(II) center, whereas the peroxo ligand in [Ni(III)(13-TMC)(O2)](+) is bound in a side-on fashion to the nickel(III) center. Reactivity studies performed with the Ni(II)-superoxo and Ni(III)-peroxo complexes toward organic substrates reveal that the former possesses an electrophilic character, whereas the latter is an active oxidant in nucleophilic reaction. PMID:23662168

  9. 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

  10. H II REGIONS, EMBEDDED PROTOSTARS, AND STARLESS CORES IN SHARPLESS 2-157

    SciTech Connect

    Chen, Chian-Chou; Williams, Jonathan P.; Pandian, Jagadheep D. E-mail: jpw@ifa.hawaii.edu

    2012-06-20

    We present arcsecond resolution 1.4 mm observations of the high-mass star-forming region, Sharpless 2-157, that reveal the cool dust associated with the first stages of star formation. These data are compared with archival images at optical, infrared, and radio wavelengths, and complemented with new arcsecond resolution mid-infrared data. We identify a dusty young H II region, numerous infrared sources within the cluster envelope, and four starless condensations. Three of the cores lie in a line to the south of the cluster peak, but the most massive one is right at the center and associated with a jumble of bright radio and infrared sources. This presents an interesting juxtaposition of high- and low-mass star formation within the same cluster which we compare with similar observations of other high-mass star-forming regions and discuss in the context of cluster formation theory.

  11. The ionization structure of helium in H II region complexes

    NASA Astrophysics Data System (ADS)

    Pena, Miriam

    1986-10-01

    Ionization structure models of H II regions are constructed to analyze the behavior of the helium ionization correction factor, icf, for combinations of different stellar radiation fields as well as for mixtures of individual H II regions of different degrees of ionization. It is found that the amount of neutral He is less than 3 percent and that icf is between 0.98 and 1.00, for H II region coomplexes ionized by OB associations where the hottest stars are earlier than O6, if the ionizing stars are distributed according to a normal IMF. This result applies for a single H II region or for a mixture of unconnected H II regions. This result implies that the He(+)/H(+) ratio observed in extragalactic H II regions of high degree of ionization corresponds to the true He/H abundance ratios.

  12. PROPERTIES OF THE COMPACT H II REGION COMPLEX G-0.02-0.07

    SciTech Connect

    Mills, E.; Morris, M. R.; Lang, C. C.; Dong, H.; Wang, Q. D.; Cotera, A.; Stolovy, S. R.

    2011-07-10

    We present new extinction maps and high-resolution Paschen-alpha images of G-0.02-0.07, a complex of compact H II regions located adjacent to the M-0.02-0.07 giant molecular cloud, 6 pc in projection from the center of the Galaxy. These H II regions, which lie in projection just outside the boundary of the Sgr A East supernova remnant, represent one of the most recent episodes of star formation in the central parsecs of the Galaxy. The 1.87 {mu}m extinctions of regions A, B, and C are almost identical, approximately 3.7 mag. Region D, in contrast, has a peak extinction of A{sub 1.87} = 5.9 mag. Adopting an extinction law specific to the Galactic center, we find that these extinctions correspond to visual extinctions of A{sub V} = 45 and A{sub V} = 71. The similar and uniform extinctions of regions A, B, and C are consistent with that expected for foreground extinction in the direction of the Galactic center, suggesting that they lie at the front side of the M-0.02-0.07 molecular cloud. Region D is more compact, has a higher extinction, and is thus suspected to be younger and embedded in a dense core in a compressed ridge on the western edge of this cloud.

  13. 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. PMID:23282905

  14. New synthetic method of zinc(II) complexes based on mixing.

    PubMed

    Takaya, Masahiro

    2005-10-01

    An environmentally benign new synthetic method of zinc(II) complexes without the use of organic solvents and alkali was developed, and several types of zinc(II) complexes in high yields were prepared by mixing solid ligands with solid Zn(OH)(2) or ZnO. PMID:16205041

  15. Synthesis and reactivity of dichloroboryl complexes of platinum(II).

    PubMed

    Charmant, Jonathan P H; Fan, Cheng; Norman, Nicholas C; Pringle, Paul G

    2007-01-01

    The reaction between [Pt(nbe)3] (nbe=norbornene), two equivalents of the phosphines PPh3, PMePh2 or PMe2Ph and 1 equivalent of BCl3 affords the platinum dichloroboryl species [PtCl(BCl2)(PPh3)2], [PtCl(BCl2)(PMePh2)2] and [PtCl(BCl2)(PMe2Ph)2]. All three complexes were characterised by X-ray crystallography and reveal that the boryl group lies trans to the chloride. With PMe3 as the phosphine, the complex [PtCl(BCl2)(PMe3)2] is isolated in high yield as a white crystalline powder although crystals suitable for X-ray crystallography were not obtained. Crystals were obtained of a product shown by X-ray crystallography to be the unusual dinuclear species [Pt2(BCl2)2(PMe3)4(micro-Cl)][BCl4] which reveals an arrangement in which two square planar platinum(II) centres are linked by a single bridging chloride which is trans to a BCl2 group on each platinum centre. The reaction of [PtCl(BCl2)(PMe3)2] with NEt3 or pyridine (py) affords the adducts [PtCl{BCl2(NEt3)}(PMe3)2] and [PtCl{BCl2(py)}(PMe3)2], respectively, both characterised spectroscopically. The reaction between [PtCl(BCl2)(PMe3)2] and either 4 equivalents of NHEt2 or piperidine (pipH) results in the mono-substituted boryl species [PtCl{BCl(NEt2)}(PMe3)2] and [PtCl{BCl(pip)}(PMe3)2], respectively, the former characterised by X-ray crystallography. Treatment of either [PtCl(BCl2)(PMe3)2] (in the presence of excess NEt3) or [PtCl{BCl(NEt2)}(PMe3)2] with catechol affords the B(cat) (cat=catecholate) derivative [PtCl{B(cat)}(PMe3)2] which is also formed in the reaction between [Pt(PMe3)4] and ClB(cat) and also from the slow decomposition of [Pt{B(cat)}2(PMe3)2] in dichloromethane over a period of months. The compound [Pt{B(cat)}2(PMe3)2] was prepared from the reaction between [Pt(PMe3)4] and B2(cat)2. PMID:17160181

  16. Reevaluation of core damage frequency in light of the occurrence of complex transients at B and W plants

    SciTech Connect

    Youngblood, R.; Hsu, C.J.; Fitzpatrick, R.; Amico, P.

    1989-01-01

    This paper presents a unified treatment of ''complex transients'' and core damage events, with the aim of relating the frequencies if the two types of events to each other and to the frequencies of their constituent events. This framework provides a basis for relating the observed frequency of certain transient types to core damage frequency, and deciding whether the occurrence of complex transients means that core damage frequency is higher than it was previously believed to be. 5 refs.

  17. 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

  18. 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.

  19. FROM PRESTELLAR TO PROTOSTELLAR CORES. II. TIME DEPENDENCE AND DEUTERIUM FRACTIONATION

    SciTech Connect

    Aikawa, Y.; Wakelam, V.; Hersant, F.; Garrod, R. T.; Herbst, E.

    2012-11-20

    We investigate the molecular evolution and D/H abundance ratios that develop as star formation proceeds from a dense molecular cloud core to a protostellar core, by solving a gas-grain reaction network applied to a one-dimensional radiative hydrodynamic model with infalling fluid parcels. Spatial distributions of gas and ice-mantle species are calculated at the first-core stage, and at times after the birth of a protostar. Gas-phase methanol and methane are more abundant than CO at radii r {approx}< 100 AU in the first-core stage, but gradually decrease with time, while abundances of larger organic species increase. The warm-up phase, when complex organic molecules are efficiently formed, is longer-lived for those fluid parcels infalling at later stages. The formation of unsaturated carbon chains (warm carbon-chain chemistry) is also more effective in later stages; C{sup +}, which reacts with CH{sub 4} to form carbon chains, increases in abundance as the envelope density decreases. The large organic molecules and carbon chains are strongly deuterated, mainly due to high D/H ratios in the parent molecules, determined in the cold phase. We also extend our model to simulate simply the chemistry in circumstellar disks, by suspending the one-dimensional infall of a fluid parcel at constant disk radii. The species CH{sub 3}OCH{sub 3} and HCOOCH{sub 3} increase in abundance in 10{sup 4}-10{sup 5} yr at the fixed warm temperature; both also have high D/H ratios.

  20. 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. PMID:25105264

  1. 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.

  2. 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.

  3. Synthesis, Characterization and Antiproliferative Activity of the Co(II), Ni(II), Cu(II), Pd(II) and Pt(II) Complexes of 2-(4-Thiazolyl)Benzimidazole (Thiabendazole)

    PubMed Central

    Glowiak, Tadeusz; Opolski, Adam; Wietrzyk, Joanna

    2001-01-01

    Complexes of 2-(4-thiazolyi)benzimidazole (thiabendazole, THBD) with Co(II), Ni(II), Cu(ll) of general formula ML2(NO3)2 H2O and complexes of Pd(II) and Pt(II) of general formula ML2Cl2 H2O have been obtained and characterized by elemental analyses, IR and far IR spectroscopy and magnetic measurements. The X-ray crystal structure of the copper(II) complex has been determined. The in vitro cell proliferation inhibitory activity of these compounds was examined against human cancer cell lines A 549 (lung carcinoma), HCV-29 T (urinary bladder carcinoma), MCF-7 (breast cancer), T47D (breast cancer), MES-SA (uterine carcinoma) and HL-60 (promyelocytic leukemia). Pt-THBD has been found to exhibit an antileukemic activity of the HL-60 line cells matching that of an arbitrary criterion. PMID:18475995

  4. 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.

  5. Binuclear Cu(II) and Co(II) Complexes of Tridentate Heterocyclic Shiff Base Derived from Salicylaldehyde with 4-Aminoantipyrine

    PubMed Central

    Al-Obaidi, Omar Hamad Shihab

    2012-01-01

    New binuclear Co(II) and Co(II) complexes of ONO tridentate heterocyclic Schiff base derived from 4-aminoantipyrine with salicylaldehyde have been synthesized and characterized on the bases of elemental analysis, UV-Vis., FT-IR, and also by aid of molar conductivity measurements, magnetic measurements, and melting points. It has been found that the Schiff bases with Cu(II) or Co(II) ion forming binuclear complexes on (1 : 1) “metal : ligand” stoichiometry. The molar conductance measurements of the complexes in DMSO correspond to be nonelectrolytic nature for all prepared complexes. Distorted octahedral environment is suggested for metal complexes. A theoretical treatment of the formation of complexes in the gas phase was studied, and this was done by using the HyperChem-6 program for the molecular mechanics and semi-empirical calculations. The free ligand and its complexes have been tested for their antibacterial activities against two types of human pathogenic bacteria: the first type (Staphylococcus aureus) is Gram positive and the second type (Escherichia coli) is Gram negative (by using agar well diffusion method). Finally, it was found that compounds show different activity of inhibition on growth of the bacteria. PMID:22611346

  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. PMID:27287543

  7. 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.

  8. Synthetic observations of first hydrostatic cores in collapsing low-mass dense cores. II. Simulated ALMA dust emission maps

    NASA Astrophysics Data System (ADS)

    Commerçon, B.; Levrier, F.; Maury, A. J.; Henning, Th.; Launhardt, R.

    2012-12-01

    Context. First hydrostatic cores are predicted by theories of star formation, but their existence has never been demonstrated convincingly by (sub)millimeter observations. Furthermore, the multiplicity in the early phases of the star formation process is poorly constrained. Aims: The purpose of this paper is twofold. First, we seek to provide predictions for ALMA dust continuum emission maps from early Class 0 objects. Second, we show to what extent ALMA will be able to probe the fragmentation scale in these objects. Methods: Following our companion paper, we post-processed three state-of-the-art radiation-magneto-hydrodynamic 3D adaptive mesh refinement calculations to compute the emanating dust emission maps. We then produced synthetic ALMA observations of the dust thermal continuum from first hydrostatic cores. Results: We present the first synthetic ALMA observations of dust continuum emission from the first hydrostatic cores. We analyze the results given by the different bands and configurations and we discuss for which combinations of the two the first hydrostatic cores would most likely be observed. We also show that observing dust continuum emission with ALMA will help in identifying the physical processes occurring within collapsing dense cores. If the magnetic field is playing a role, the emission pattern will show evidence of a pseudo-disk and even of a magnetically driven outflow, which pure hydrodynamical calculations cannot reproduce. Conclusions: The capabilities of ALMA will enable us to make significant progress towards understanding the fragmentation at the early Class 0 stage and discovering first hydrostatic cores.

  9. 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. PMID:21764045

  10. From accommodation zones to metamorphic core complexes: Tracking the progressive development of major normal fault systems

    SciTech Connect

    Faulds, J.E. . Dept. of Geology)

    1992-01-01

    The along-strike dimension in rifted continental crust is critical to assessing models of continental extension because individual normal faults or fault systems can potentially be traced from their tips in accommodation zones to their culminations in metamorphic core complexes. Accommodation zones and the linkages between the zones and core complexes have not been thoroughly studied or incorporated extensively into models of continental extension. Regionally extensive, gently dipping normal faults (i.e., detachment faults) that surface in metamorphic core complexes terminate and flip polarity in accommodation zones. Diametrical lateral transport of upper-plate rocks in positively dipping detachment terranes should presumably induce strike-slip faulting on segments of accommodation zones paralleling the extension direction. Most accommodation zones correspond, however, to belts of intermeshing conjugate normal faults with little strike-slip faulting. Normal faults simply terminate along-strike in the zones with little, if any, transfer of slip to strike-slip faults. Decreases in cumulative strain within individual normal fault systems toward some accommodation zones cannot alone account for the lack of strike-slip faulting. These findings pose a serious challenge to generally accepted notions of large-magnitude, lateral motion of parts of detachment terranes. Large-scale lateral translations of rifted continental crust may be governed more by discrete axes of extension than by detachment geometries. The dovetail-like interfingering of conjugate normal fault systems and attendant tilt-block domains observed in some accommodation zones (e.g., Colorado River extensional corridor, US) does suggest, however, that at least some major normal faults projecting into the zones from metamorphic core complexes have listric geometries that flatten out at relatively shallow depths.

  11. Syntheses, crystal structures and spectroscopic properties of copper(II)-tetracyanometallate(II) complexes with nicotinamide and isonicotinamide ligands

    NASA Astrophysics Data System (ADS)

    Sayın, Elvan; Kürkçüoğlu, Güneş Süheyla; Yeşilel, Okan Zafer; Hökelek, Tuncer

    2015-09-01

    Four new one dimensional (1D) cyanide complexes, namely {[Cu(NH3)4(μ-na)][M‧(CN)4]}n and {[Cu(NH3)2(ina)2M‧(μ-CN)2(CN)2]}n (M‧(II) = Pd (1 and 3) or Pt (2 and 4), na:nicotinamide and ina:isonicotinamide) have been synthesized and characterized by elemental, spectral (FT-IR and Raman), and thermal (TG, DTG and DTA) analyses. The crystal structures of complexes 1-3 have been determined by single crystal X-ray diffraction technique. In complexes 1 and 2, na ligand is coordinated to the adjacent Cu(II) ions as a bridging ligand, giving rise to 1D linear cationic chain and the [M‧(CN)4]2- anionic complex acts as a counter ion. Complexes 3 and 4 are also 1D linear chain in which two cyanide ligands bridged neighboring M‧(II) and Cu(II) ions, while ina ligand is coordinated Cu(II) ion through nitrogen atom of pyridine ring. In the complexes, the Cu(II) ions adopt distorted octahedral geometries, while M‧(II) ions are four coordinated with four carbon atoms from cyanide ligands in square-planar geometries. The adjacent chains are further stacked through intermolecular hydrogen bond, Nsbnd Hṡṡṡπ, Csbnd H⋯M‧ and M‧⋯π interactions to form 3D supramolecular networks. Vibration assignments are given for all the observed bands. In addition, thermal stabilities of the compounds are also discussed.

  12. Synthesis and spectral feature of benzophenone-substituted thiosemicarbazones and their Ni(II) and Cu(II) complexes

    NASA Astrophysics Data System (ADS)

    El-Asmy, A. A.; Al-Hazmi, G. A. A.

    2009-01-01

    The ligational behavior of 2-hydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone N-substituted thiosemicarbazones towards Ni(II) and Cu(II) ions has been investigated. The isolated complexes were identified by elemental analyses, molar conductance, magnetic moment, IR, UV-vis and ESR spectral studies. The IR spectra indicated that the investigated thiosemicarbazones lost the N 2 proton or the N 2 and OH protons and act as mononegative or binegative tridentate ligands. The ligands containing methoxy group facilitate the deprotonation of OH by resonance more than the SH. Most of the Ni(II) complexes measured subnormal magnetic moments due to square-planar + tetrahedral configuration and supported by the electronic spectra. The percentage of square-planar to tetrahedral was calculated and found in agreement with the ligand splitting energy (10Dq). Also, Cu(II) complexes measured subnormal values due to the interaction between copper centers; the lower the value the higher the interaction. It was found that the substitutent has a noticeable effect on the distortion of the complex. The ESR spectra of some solid Cu(II) complexes at room temperature exhibit g|| > g⊥ > 2.0023 confirming a square-planar structure.

  13. Strategies for crystallizing a chromatin protein in complex with the nucleosome core particle

    PubMed Central

    Makde, Ravindra D.; Tan, Song

    2013-01-01

    The molecular details for how chromatin factors and enzymes interact with the nucleosome are critical to understand fundamental genetic processes including cell division and gene regulation. A structural understanding of such processes has been hindered by the difficulty producing diffraction quality crystals of chromatin proteins in complex with the nucleosome. We describe here the steps used to grow crystals of the 300 kDa RCC1 chromatin factor/nucleosome core particle complex which diffract to 2.9 Å resolution. These steps included both pre- and post-crystallization strategies potentially useful to other complexes. We screened multiple variant RCC1-nucleosome core particle complexes assembled using different RCC1 homologs and deletion variants, and nucleosomes containing nucleosomal DNA with different sequences and lengths as well as histone deletion variants. We found that using RCC1 from different species produced different crystal forms of the RCC1-nucleosome complex consistent with key crystal packing interactions mediated by RCC1. Optimization of post-crystallization soaks to dehydrate the crystals dramatically improved the diffraction quality of the RCC1/nucleosome crystal from 5.0 to 2.9 Å resolution. PMID:23928047

  14. Sequential Development of Interfering Metamorphic Core Complexes: Numerical Experiments and Comparison to the Cyclades, Greece

    NASA Astrophysics Data System (ADS)

    Tirel, C.; Gautier, P.; van Hinsbergen, D.; Wortel, R.

    2007-12-01

    The Cycladic extensional province (Greece) contains classical examples of metamorphic core complexes (MCCs), where exhumation was accommodated along multiple interfering and/or sequentially developed syn- and antithetic extensional detachment zones. Previous studies on the development of MCCs did not take into account the possible interference between multiple and closely spaced MCCs. In the present study, we have performed new lithosphere-scale experiments in which the deformation is not a priori localized so as to explore the conditions of the development of several MCCs in a direction parallel to extension. In a narrow range of conditions, MCCs are closely spaced, interfere with each other, and develop in sequence. From a comparison between numerical results and geological observations, we find that the Cyclades metamorphic core complexes are in good agreement with the model in terms of Moho geometry and depth, kinematic and structural history, timing and duration of core complex formation and metamorphic history. We infer that, for Cycladic MCC-type to develop, an initial crustal thickness prior to the onset of post-orogenic extension between 40 and 44 km, a boundary velocity close to 2 cm/yr and an initial thermal lithospheric thickness of about 60 km are required. The latter may be explained by a significant heating due to delamination of subducting continental crust or vigorous small-scale thermal convection.

  15. 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. PMID:11418853

  16. Synthesis, fluorescence study and biological evaluation of three Zn(II) complexes with Paeonol Schiff base.

    PubMed

    Qin, Dong-dong; Yang, Zheng-yin; Qi, Gao-fei

    2009-10-01

    The synthesis of three Paeonol Schiff base ligand and their Zn(II) complexes are reported. The complexes were fully characterized by IR, (1)H NMR, elemental analysis and molar conductivity. The experiment results show the three Zn(II) complexes can emit bright fluorescence at room temperature in DMF solution and solid state. The fluorescence quantum yields (Phi) of three Schiff base ligands and their Zn(II) complexes were calculated using quinine sulfate as the reference with a known Phi(R) of 0.546 in 1.0N sulfuric acid. Furthermore, in order to develop these Zn(II) complexes' biological value, the antioxidant activities against hydroxyl radicals (OH*) were evaluated. The results show the three complexes possess excellent ability to scavenge hydroxyl radicals. PMID:19632146

  17. Synthesis, fluorescence study and biological evaluation of three Zn(II) complexes with Paeonol Schiff base

    NASA Astrophysics Data System (ADS)

    Qin, Dong-dong; Yang, Zheng-yin; Qi, Gao-fei

    2009-10-01

    The synthesis of three Paeonol Schiff base ligand and their Zn(II) complexes are reported. The complexes were fully characterized by IR, 1H NMR, elemental analysis and molar conductivity. The experiment results show the three Zn(II) complexes can emit bright fluorescence at room temperature in DMF solution and solid state. The fluorescence quantum yields ( Φ) of three Schiff base ligands and their Zn(II) complexes were calculated using quinine sulfate as the reference with a known ΦR of 0.546 in 1.0N sulfuric acid. Furthermore, in order to develop these Zn(II) complexes' biological value, the antioxidant activities against hydroxyl radicals (OH rad ) were evaluated. The results show the three complexes possess excellent ability to scavenge hydroxyl radicals.

  18. 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.

  19. Pyrrolidine dithiocarbamate-zinc(II) and -copper(II) complexes induce apoptosis in tumor cells by inhibiting the proteasomal activity☆

    PubMed Central

    Milacic, Vesna; Chen, Di; Giovagnini, Lorena; Diez, Alejandro; Fregona, Dolores; Dou, Q. Ping

    2013-01-01

    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 IC50 value of 13.8 μM, which was less potent than copper(II) chloride (IC50 5.3 μM). 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. PMID:18501397

  20. 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.

  1. 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.

  2. 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+). PMID:24797021

  3. Synthesis of New Five Coordinated Copper(II) and Nickel(II) Complexes of L-Valine and Kinetic Study of Copper(II) with Calf Thymus DNA

    PubMed Central

    Tak, Aijaz Ahmad; Arjmand, Farukh

    2002-01-01

    Five coordinated novel complexes of Cu II and Ni II have been synthesized from benzil and 1,3- diaminopropane- Cu II / Ni II complex and characterized by elemental analysis, i.r., n.m.r., e.p.r, molar conductance and u.v-vis, spectroscopy. The complexes are ionic in nature and exhibit pentaeoordinated geometry around the metal ion. The reaction kinetics of C 25 H 36 N 5 O 2 CuCl with calf thymus DNA was studied by u.v-vis, spectroscopy in aqueous medium. The complex after interaction with calf thymus DNA shows shift in the absorption spectrum and hypochromicity indicating an intercalative binding mode. The K obs values have been calculated under pseudo-first order conditions. The redox behaviour of complex C 25 H 36 N 5 O 2 CuCl in the presence and in the absence of calf thymus DNA in the aqueous solution has been investigated by cyclic voltammetry. The cyclic voitammogram exhibits one quasi-reversible redox wave corresponding to Cu II / Cu I redox couple with E 1 / 2 values of -0.377 and -0.237 V respectively at a scan rate of 0.1V s - 1 .On interaction with calf thymus DNA, the complex C 25 H 36 N 5 O 2 CuCl exhibits shifts in both E p as well as in E 1 / 2 values, indicating strong binding of the complex to the calf thymus DNA. PMID:18475428

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

    PubMed

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

    2015-03-01

    The potentiometric and conductometric titration methods have been used to characterize the stability of series of VO(IV)-, Co(II)- and Ni(II)-oxydiacetato complexes in DMSO-water solutions containing 0-50 % (v/v) DMSO. The influence of DMSO as a co-solvent on the stability of the complexes as well as the oxydiacetic acid was evaluated. Furthermore, the reactivity of the complexes towards superoxide free radicals was assessed by employing the nitro blue tetrazolium (NBT) assay. The biological properties of the complexes were investigated in relation to their cytoprotective activity against the oxidative damage generated exogenously by using hydrogen peroxide in the Human Dermal Fibroblasts adult (HDFa) cell line as well as to their antimicrobial activity against the bacteria (Bacillus subtilis, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis). The relationship between physicochemical and biological properties of the complexes was discussed. PMID:25488702

  5. Unprecedented Alkene Complex of Zinc(II): Structures and Bonding of Divinylzinc Complexes

    PubMed Central

    Wooten, Alfred; Carroll, Patrick J.; Maestri, Aaron G.

    2008-01-01

    This report describes the solid state structures of a series of divinylzinc complexes, one of which represents the only structurally characterized zinc(II) π-complex. Vinylzinc reagents, Zn[C(Me)=CH2]2 (1) and Zn[C(H)=CMe2]2 (2), have been synthesized and isolated as white crystalline solids in 66% and 72% yield, respectively. Each compound exhibits an infinite polymeric architecture in the solid state via a series of zinc-π (1) and zinc-σ-bonded (2) bridging interactions. Addition of chelating ligands to these divinylzinc compounds allowed isolation of the monomeric adducts (bipy)Zn[C(Me)=CH2]2 (1·bipy), (tmeda)Zn[C(Me)=CH2]2 (1·tmeda), (bipy)Zn[C(H)=CMe2]2 (2·bipy), and (tmeda)Zn[C(H)=CMe2]2 (2·tmeda), of which (1·bipy), (2·bipy), and (2·tmeda) have been characterized crystallography. PMID:16594699

  6. 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. PMID:8841130

  7. Mixed-ligand MnII and CuII complexes with alternating 2,2'-bipyrimidine and terephthalate bridges.

    PubMed

    Poleti, Dejan; Rogan, Jelena; Rodić, Marko V; Radovanović, Lidija

    2015-02-01

    The novel polymeric complexes catena-poly[[diaquamanganese(II)]-μ-2,2'-bipyrimidine-κ(4)N(1),N(1'):N(3),N(3')-[diaquamanganese(II)]-bis(μ-terephthalato-κ(2)O(1):O(4))], [Mn2(C8H4O4)2(C8H6N4)(H2O)4]n, (I), and catena-poly[[[aquacopper(II)]-μ-aqua-μ-hydroxido-μ-terephthalato-κ(2)O(1):O(1')-copper(II)-μ-aqua-μ-hydroxido-μ-terephthalato-κ(2)O(1):O(1')-[aquacopper(II)]-μ-2,2'-bipyrimidine-κ(4)N(1),N(1'):N(3),N(3')] tetrahydrate], {[Cu3(C8H4O4)2(OH)2(C8H6N4)(H2O)4]·4H2O}n, (II), containing bridging 2,2'-bipyrimidine (bpym) ligands coordinated as bis-chelates, have been prepared via a ligand-exchange reaction. In both cases, quite unusual coordination modes of the terephthalate (tpht(2-)) anions were found. In (I), two tpht(2-) anions acting as bis-monodentate ligands bridge the Mn(II) centres in a parallel fashion. In (II), the tpht(2-) anions act as endo-bridges and connect two Cu(II) centres in combination with additional aqua and hydroxide bridges. In this way, the binuclear [Mn2(tpht)2(bpym)(H2O)4] entity in (I) and the trinuclear [Cu3(tpht)2(OH)2(bpym)(H2O)4]·4H2O coordination entity in (II) build up one-dimensional polymeric chains along the b axis. In (I), the Mn(II) cation lies on a twofold axis, whereas the four central C atoms of the bpym ligand are located on a mirror plane. In (II), the central Cu(II) cation is also on a special position (site symmetry -1). In the crystal structures, the packing of the chains is further strengthened by a system of hydrogen bonds [in both (I) and (II)] and weak face-to-face π-π interactions [in (I)], forming three-dimensional metal-organic frameworks. The Mn(II) cation in (I) has a trigonally deformed octahedral geometry, whereas the Cu(II) cations in (II) are in distorted octahedral environments. The Cu(II) polyhedra are inclined relative to each other and share common edges. PMID:25652277

  8. A heterobimetallic superoxide complex formed through O2 activation between chromium(II) and a lithium cation.

    PubMed

    Schax, Fabian; Suhr, Simon; Bill, Eckhard; Braun, Beatrice; Herwig, Christian; Limberg, Christian

    2015-01-19

    The reaction of 1,1,3,3-tetraphenyl-1,3-disiloxandiol (LH2) with n-butyllithium and CrCl2 results in a mononuclear chromium(II) complex (1) that further reacts with O2 at low temperatures to yield a mononuclear chromium(III) superoxide complex [L2CrO2(THF)][Li2(THF)3] (2). The crystal structure revealed that the chromium superoxido entity is stabilized by the coordination to an adjacent lithium cation. Complex 2 thus contains an unprecedented heterobimetallic [Cr(III)(μ-O2)Li(+)] core; beyond this it is the first chromium superoxide for which a temperature-dependent magnetic characterization could be achieved, and the first structurally characterized representative with chromium in an exclusive O-donor environment. PMID:25477030

  9. Synthesis, characterization and biocidal activity of some transition metal(II) complexes with isatin salicylaldehyde acyldihydrazones.

    PubMed

    Singh, Vinod P; Singh, Shweta; Singh, Divya P

    2012-06-01

    Cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes with two new unsymmetrical ligands, isatin salicylaldehyde oxalic acid dihydrazide (isodh) and isatin salicylaldehyde malonic acid dihydrazide (ismdh) were synthesized and characterized by elemental analyses, electrical conductance, magnetic moments, electronic, NMR, ESR and IR spectral studies. The isodh acts as a dibasic tetra dentate ligand bonding through two >C=N-, a deprotonated phenolate and deprotonated indole enolate groups to the metal. The ismdh ligand shows monobasic tetra dentate behaviour in bonding with metal ion through two >C=N-, indole >C=O and a deprotonated phenolate group. The electronic spectral data suggest 4-coordinate square planar geometry for Co(II), Ni(II) and Cu(II) complexes of isodh, whereas, 6-coordinate octahedral structure for the ismdh complexes. The ESR studies also indicate a square planar and distorted octahedral environment around Cu(II) for isodh and ismdh complexes, respectively. Most of the metal complexes show better antifungal activity than the standard and a significant antibacterial activity against various fungi and bacteria. PMID:21679052

  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. 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

  12. Oceanic core complexes and ancient oceanic lithosphere: Insights from Iapetan and Tethyan ophiolites (Canada and Albania)

    NASA Astrophysics Data System (ADS)

    Tremblay, Alain; Meshi, Avni; Bédard, Jean H.

    2009-07-01

    Oceanic ridges are extensional environments characterized by brittle to ductile normal faulting and episodic magma supply. Studies in modern oceanic settings suggest that the interplay of low-angle detachments and high-angle normal faults locally lead to the exhumation of lower crust and upper mantle peridotites to the seafloor as oceanic core complexes. Along the Mid-Atlantic ridge, core complexes typically occur in inside corners of intersections between the ridge axis and major transform faults. The core complexes were exhumed by movement along long-lived detachment faults that extend for 10s of km, and that are crosscut by high-angle normal faults oriented parallel to the rift axis. Ridge segments with abundant detachments would be characterized by lithosphere having little or no upper crust. Similar features in ophiolites may also reflect the dominance of amagmatic extension. This contribution presents two examples of fossilized oceanic core complexes preserved in the Canadian Appalachian and Albanian Dinaride ophiolite belts. In the Canadian Appalachians, the Southern Quebec ophiolites experienced two Paleozoic orogenies after their obduction onto the Laurentian margin. Although locally obscured by tectonic fabrics and structures, the original relationships between the ophiolitic mantle, the overlying plutonic section, and onlapping Ordovician siliciclastic rocks are well-preserved in the Thetford-Mines ophiolite which also shows similarities with lithological and structural features of the Mirdita ophiolite, where conformable contacts between the sedimentary cover sequence (debris flows and flysch deposits) and the mantle and crustal sections are superbly exposed. The Jurassic Mirdita ophiolite in Albania underlies ca. 4000 km 2 and was only slightly affected by the Tertiary Alpine orogeny of Eastern Europe. Well-exposed sections of the ophiolite suggest that the oceanic mantle was exhumed prior to obduction and locally records the formation of an oceanic

  13. Ni(II), Cu(II), and Zn(II) Diethyldithiocarbamate Complexes Show Various Activities Against the Proteasome in Breast Cancer Cells

    PubMed Central

    Cvek, Boris; Milacic, Vesna; Taraba, Jan; Dou, Q. Ping

    2008-01-01

    A series of three complexes with diethyldithiocarbamate ligand and three different metals (Ni, Cu, Zn) was prepared, confirmed by X-ray crystallography, and tested in human breast cancer MDA-MB-231 cells. Zinc and copper complexes, but not nickel complex, were found to be more active against cellular 26S proteasome than against purified 20S proteasome core particle. One of the possible explanations is inhibition of JAMM domain in the 19S proteasome lid. PMID:18816109

  14. Interactions of the anticancer antibiotic altromycin B with copper(II), palladium(II) and platinum(II) ions and in vitro activity of the formed complexes.

    PubMed

    Nikolis, Nikolaos; Methenitis, Constantinos; Pneumatikakis, George; Fiallo, Marina M L

    2002-04-10

    Interaction of the anticancer antibiotic altromycin B with Cu(II), Pd(II) and Pt(II) ions was studied using 1H-NMR, EPR, electronic absorption and circular dichroism spectroscopy. The results derived from NMR studies where that the Pt(II) and Pd(II) ions interact with the nitrogen atom of the dimethylamino group of the C(10)-disaccharide, while the C(2)-epoxide group does not participate and remains intact. Cu(II) ions interact in a different way with altromycin B as was concluded by EPR and circular dichroism spectra. Altromycin B coordinates to the Cu(II) ions via the oxygen atoms of the C(11) phenolic and the C(12) carbonyl group while the nitrogen atom does not participate in the complexation. The presence of these metal ions improves the stability of altromycin B in solution. These complexes were studied in vitro against K562 leukemia sensitive and doxorubicin-resistant cells and GLC4 lung tumor cells, sensitive and doxorubicin-resistant. The activity of the complexes compared to the free drug is improved against resistant cells and is affected moderately against sensitive cells. Finally, 20% of platinum added as altromycin B metal complex entered GLC4 cells. PMID:11931973

  15. Crystal structure, DFT, spectroscopic and biological activity evaluation of analgin complexes with Co(ii), Ni(ii) and Cu(ii).

    PubMed

    Mansour, Ahmed M

    2014-11-14

    Reaction of analgin (NaL) with Co(ii), Ni(ii) and Cu(ii) salts in ethanol affords complexes of the type [ML2], which were characterized by elemental analysis, FT IR, UV-Vis, EPR, TG/DTA, magnetic susceptibility and conductance measurements. The copper(ii) complex crystallizes in the orthorhombic Pbca space group. Analgin behaves as a mono-negatively tridentate ligand via pyrazolone O, sulfonate O and tertiary amino groups. The interaction of the tertiary nitrogen with M(n+) ions is the main factor which determines the stability of complexes as revealed from natural bond orbital analysis data, where the binding energy of [ML2] decreases with an increase in the bond length of the M-N bond. Time-dependent density functional theory calculations were applied in order to realize the electronic structures and to explain the related experimental observations. The anti-bacterial activity was studied on Staphylococcus aureus and Escherichia coli. Coordination of analgin to Ni(ii) and Cu(ii) leads to a significant increase in its antibacterial activity as compared with the Co(ii) complex. PMID:25231028

  16. The properties of solid Zn(II)-amino acid complexes in the form of suspensions.

    PubMed

    Dolińska, B

    2001-10-01

    An investigation was made into the experimental conditions for the formation of poorly soluble complexes of the divalent Zinc(II) combined with the following selected amino acids: tyrosine, tryptophan, cysteine, histidine, and alanine, in the form of suspensions for parenteral administration. The number of Zn(II)-binding sites in the amino acid (n) as well as the amino acid affinity to Zn(II) (Ka), were determined. Cysteine was found to have the highest number of Zn(II)-binding sites--3, whereas alanine the lowest--1. In the conditions described herein, Zn(II) amino acid complexes of diverse stability (durability) were obtained. The analysis of the kinetics of the binding revealed that the most stable complexes were those formed by Zn(II) in combination with tryptophan (Ka = 405.78 microM(-1) +/- 12.17), and with tyrosine (Ka = 343.88 microM +/- 22.35); whereas the least stable complexes were those formed by Zn(II) in combination with histidine (Ka = 29.90 microM +/- 4.78), and with alanine (Ka = 13.0 microM(-1) +/- 1.04). Cysteine formed complexes of intermediate stability (Ka = 168.53 microM(-1) +/- 12.36). The stability ofthe Zn(II) amino acid complexes obtained was conditioned by both the molecular weight (P = 0.033) of the amino acid and its isoelectric point (P < 0.001). PMID:11718265

  17. 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

    2011-01-01

    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. PMID:21996717

  18. 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. PMID:27001529

  19. 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. PMID:25398505

  20. Spectroscopic and biological approach of Ni(II), Cu(II) and Co(II) complexes of 4-methoxy/ethoxybenzaldehyde thiosemicarbazone glyoxime.

    PubMed

    Babahan, Ilknur; Eyduran, Fatih; Coban, Esin Poyrazoglu; Orhan, Nil; Kazar, Didem; Biyik, Halil

    2014-01-01

    Two novel vicinal dioxime ligands containing (4-methoxybenzaldehyde thiosemicarbazone glyoxime (L(1)H2) or 4-ethoxybenzaldehyde thiosemicarbazone glyoxime (L(2)H2)) thiosemicarbazone units were synthesized and characterized using (1)H NMR, (13)C NMR, HMQC, MS, infrared and, UV-VIS. spectroscopy, elemental analysis, and magnetic susceptibility measurements. Mononuclear nickel(II), copper(II) and cobalt(II) complexes with a metal:ligand ratio of 1:2 for L(1)H2 and L(2)H2 were also synthesized. The effect of pH and solvent on the absorption spectra of both ligands and complexes was determined. IR spectra show that the ligands act in a bidentate manner and coordinates N4 donor groups of the ligands to Ni(II), Cu(II) and Co(II) ions. The detection of H-bonding (O-H⋯O) in the [M(LH)2] metal complexes by IR spectra supported the square-planar MN4 coordination of mononuclear complexes. The antimicrobial activities of compounds L(1)H2, L(2)H2, and their Ni(II), Cu(II) and Co(II) complexes were evaluated using the disc diffusion method against 12 bacteria and 4 yeasts. The minimal inhibitory concentrations (MICs) against 7 bacteria and 3 yeasts were also determined. Among the test compounds attempted, L(1)H2, [Ni(L1H)2], [Cu(L1H)2], L2H2, [Ni(L2H)2] and [Cu(L2H)2] showed some activities against certain Gram-positive bacteria and some of the yeasts tested. PMID:24239764

  1. Single molecule microscopy reveals mechanistic insight into RNA polymerase II preinitiation complex assembly and transcriptional activity

    PubMed Central

    Horn, Abigail E.; Kugel, Jennifer F.; Goodrich, James A.

    2016-01-01

    Transcription by RNA polymerase II (Pol II) is a complex process that requires general transcription factors and Pol II to assemble on DNA into preinitiation complexes that can begin RNA synthesis upon binding of NTPs (nucleoside triphosphate). The pathways by which preinitiation complexes form, and how this impacts transcriptional activity are not completely clear. To address these issues, we developed a single molecule system using TIRF (total internal reflection fluorescence) microscopy and purified human transcription factors, which allows us to visualize transcriptional activity at individual template molecules. We see that stable interactions between polymerase II (Pol II) and a heteroduplex DNA template do not depend on general transcription factors; however, transcriptional activity is highly dependent upon TATA-binding protein, TFIIB and TFIIF. We also found that subsets of general transcription factors and Pol II can form stable complexes that are precursors for functional transcription complexes upon addition of the remaining factors and DNA. Ultimately we found that Pol II, TATA-binding protein, TFIIB and TFIIF can form a quaternary complex in the absence of promoter DNA, indicating that a stable network of interactions exists between these proteins independent of promoter DNA. Single molecule studies can be used to learn how different modes of preinitiation complex assembly impact transcriptional activity. PMID:27112574

  2. 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).

  3. Aromatic C-nitrosation by a copper(II)-nitrosyl complex.

    PubMed

    Rout, Kanhu Charan; Mondal, Biplab

    2015-01-28

    Copper(II) complex of 4-amino-3-hydroxy-1-sulphonic acid was synthesized and characterized. Upon addition of nitric oxide, the copper(II) center of the complex in methanol was found to undergo reduction through an unstable copper(II)-nitrosyl intermediate. The formation of the intermediate was confirmed by UV-visible and FT-IR spectroscopy. The reduction of the copper(II) center was accompanied with a simultaneous C-nitrosation of the aromatic ring of the ligand. The C-nitrosation product was isolated and characterized by various spectroscopic analyses. PMID:25476484

  4. A Catalog of Low-mass Star-forming Cores Observed with SHARC-II at 350 μm

    NASA Astrophysics Data System (ADS)

    Suresh, Akshaya; Dunham, Michael M.; Arce, Héctor G.; Evans, Neal J., II; Bourke, Tyler L.; Merello, Manuel; Wu, Jingwen

    2016-08-01

    We present a catalog of low-mass dense cores observed with the SHARC-II instrument at 350 μm. Our observations have an effective angular resolution of 10″, approximately 2.5 times higher than observations at the same wavelength obtained with the Herschel Space Observatory, albeit with lower sensitivity, especially to extended emission. The catalog includes 81 maps covering a total of 164 detected sources. For each detected source, we tabulate basic source properties including position, peak intensity, flux density in fixed apertures, and radius. We examine the uncertainties in the pointing model applied to all SHARC-II data and conservatively find that the model corrections are good to within ∼3″, approximately 1/3 of the SHARC-II beam. We examine the differences between two array scan modes and find that the instrument calibration, beam size, and beam shape are similar between the two modes. We also show that the same flux densities are measured when sources are observed in the two different modes, indicating that there are no systematic effects introduced into our catalog by utilizing two different scan patterns during the course of taking observations. We find a detection rate of 95% for protostellar cores but only 45% for starless cores, and demonstrate the existence of a SHARC-II detection bias against all but the most massive and compact starless cores. Finally, we discuss the improvements in protostellar classification enabled by these 350 μm observations.

  5. 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

    2016-08-01

    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

  6. 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.

  7. Polymer complexes. LIV. Structural and spectral studies of supramolecular coordination polymers built from Ni(II), Fe(II) and Pd(II) with sulphadrug

    NASA Astrophysics Data System (ADS)

    El-Sonbati, A. Z.; Belal, A. A. M.; Diab, M. A.; Mohamed, R. H.

    2011-03-01

    Polymer complexes of p-acrylamidyl sulphaguanidine (HL) with Ni(II), Fe(II) and Pd(II) salts have been prepared. The structures of the polymer complexes were elucidated using elemental analysis, 1H NMR, UV-Vis, IR spectroscopies, magnetic moment, molar conductance and thermal analysis. The polymer complexes were isolated in 1:1 and 1:2 (M:L) ratios. The solid monocomplexes (1:1) (M:L) were isolated in the general formula [Fe(HL)O 2SO 2(OH 2) 2]. The biscomplexes (1:2) (M:L) solid chelates found to have the general formula [Ni(HL) 2X 2] n (X = Cl -, Br -, I -, NO3-, NCS -), [Fe(HL)(en)(OSO 3)(OH 2)] n and [Ni(HL) 2(Py) 2] nX 2, while {[Pd(L)X] 2} n (1:1) (X = Cl - or Br -). In all the polymer complexes the ligand and anions were found to be coordinated to the Ni(II) and Fe(II) ions. The bidentate nature of the ligand is evident from IR spectra. The magnetic and spectroscopic data indicate a octahedral geometry for complexes. The thermal behaviour of these chelates shows that the hydrated complexes loss water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps.

  8. 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.

  9. Discontinuous phase transition in a core contact process on complex networks

    NASA Astrophysics Data System (ADS)

    Chae, Huiseung; Yook, Soon-Hyung; Kim, Yup

    2015-02-01

    To understand the effect of generalized infection processes, we suggest and study the core contact process (CCP) on complex networks. In CCP an uninfected node is infected when at least k different infected neighbors of the node select the node for the infection. The healing process is the same as that of the normal CP. It is analytically and numerically shown that discontinuous transitions occur in CCP on random networks and scale-free networks depending on infection rate and initial density of infected nodes. The discontinuous transitions include hybrid transitions with β = 1/2 and β = 1. The asymptotic behavior of the phase boundary related to the initial density is found analytically and numerically. The mapping between CCP with k and static (k+1)-core percolation is supposed from the (k+1)-core structure in the active phase and the hybrid transition with β = 1/2. From these properties of CCP one can see that CCP is one of the dynamical processes for the k-core structure on real networks.

  10. 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.

  11. 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

  12. Nature and origin of seismic reflection fabric, Ruby-East Humboldt Metamorphic Core Complex, Nevada

    NASA Astrophysics Data System (ADS)

    Valasek, P. A.; Snoke, A. W.; Hurich, C. A.; Smithson, S. B.

    1989-04-01

    Seismic reflection profiling across exposed upper and middle crustal rocks of the Ruby-East Humboldt metamorphic core complex delineates important characteristics of the crustal structure developed during Tertiary extensional deformation. The goals of this study were to trace a Tertiary extensional shear zone from mylonitic surface outcrops into a seismic section and to characterize the deeper crustal fabric associated with the polyphase deformational history of the complex. Reflections in the shallow surface correlate with a plastic to brittle shear zone that formed during the tectonic unroofing of the middle crustal rocks. Constructive interference from strong planar layering in the mylonitic shear zone is considered chiefly responsible for generating the reflections. East and southwest dipping reflectors in the seismic section appear to correlate with exposed, opposing dipping mylonitic foliation domains. The opposing dips of the mylonitic layering may reflect warping of the normal-sense shear zone during tectonic exhumation coupled with an overall anastomosing character. Deeper in the section, a heterogeneous reflection character correlates with increases in velocity shown from wide-angle measurements in this region and is interpreted as penetrative fabric originating from extensional flow facilitated by broad-scale pure shear and localized simple shear. Lower crustal rocks apparently achieved granulite facies metamorphism during extension. A maximum of 6-8 km of mafic material could have been added to the crust during Cenozoic extension. The Moho reflection has such a high amplitude that it may be caused by partially molten rocks interleaved with peridotite. Reflections from the Moho show no significant upwarping of the base of the crust beneath the core complex. This suggests that the lower-crustal configuration is at least as young as the period of extensional activity that lasted from approximately 40 to 20 Ma which was responsible for the exhumation of the

  13. 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

  14. 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…

  15. Complexes of sulfur-containing ligands. I. Factors influencing complex formation between D-penicillamine and copper (II) ion.

    PubMed

    Gergely, A; Sóvágó, I

    1978-07-01

    Complex formation and redox reactions between copper (II) ion and D-penicillamine were studied in detail as functions of the metal/-ligand ratio and the concentration of halide ions. It was established that a copper (I)- D-penicillamine polymeric complex of amphoteric character is formed when excess D-penicillamine is present. When the D-penicillamine/copper (II) ratio = 1.45 in the starting reaction mixture, a mixed valence complex with an intense red-violet color is formed. The formation of this compound, which contains 44% copper (II) ion, is greatly influenced by the experimental conditions, primarily by the concentration of halide ions. The main chemical and physical characteristics of the mixed valence complex were determined via magnetic and spectroscopic measurements. It was further established that a very intense blue complex is formed when the D-penicillamine/copper (II) ratio = 2 and halide ions are present. On the basis of the nature of the products formed under various conditions it was concluded that the copper (II)-D-penicillamine system may serve as a good model for studying the binding sites of copper-containing proteins. PMID:210846

  16. Mitochondrial myopathy, cardiomyopathy, and pontine signal changes in an adult patient with isolated complex II deficiency.

    PubMed

    Sonam, Kothari; Bindu, Parayil Sankaran; Taly, Arun B; Nalini, Atchayaram; Govindaraju, Chikkanna; Aravinda, Hanumanthapura R; Khan, Nahid Akthar; Thangaraj, Kumaraswamy; Gayathri, Narayanappa

    2014-12-01

    Mitochondrial disorders resulting from an isolated deficiency of complex II of the respiratory chain is rarely reported. The phenotypic spectrum associated with these disorders is heterogeneous and still expanding. This report describes a patient who presented with myopathy, dilated cardiomyopathy, and pontine signal changes on magnetic resonance imaging. Muscle biopsy showed total absence of succinate dehydrogenase on enzyme histochemistry, negative succinate dehydrogenase subunit A (SDHA) activity on immunohistochemistry, and ultrastructural evidence of mitochondrial aggregates of varying sizes confirming the diagnosis of complex II deficiency. A unique phenotype with complex II deficiency is reported. PMID:25415517

  17. Manganese(II) complexes of substituted di-2-pyridyl ketone thiosemicarbazones: Structural and spectral studies

    NASA Astrophysics Data System (ADS)

    Philip, Varughese; Suni, V.; Kurup, Maliyeckal R. Prathapachandra; Nethaji, Munirathinam

    2006-05-01

    The reaction between manganese(II) acetate and two substituted thiosemicarbazones derived from di-2-pyridyl ketone (HL) in 1:2 molar ratio produces new complexes of general formula [MnL 2]. The thiosemicarbazone moiety in HL deprotonates and gets coordinated to Mn(II) through the azomethine nitrogen, one of the pyridyl nitrogens, and the thiolate sulfur in both the complexes. The crystal structure of [ MnL21] was established by single crystal X-ray diffraction and the compound crystallizes into a monoclinic lattice with P2 1/ c space group. Manganese(II) exists in a distorted octahedral geometry in the complexes.

  18. 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.

  19. Induction of class II major histocompatibility complex expression in human multiple myeloma cells by retinoid.

    PubMed

    Sanda, Takaomi; Iida, Shinsuke; Kayukawa, Satoshi; Ueda, Ryuzo

    2007-01-01

    Class II major histocompatibility complex (MHC II) is normally silenced in plasma/multiple myeloma (MM) cells at the transcriptional level through downregulation of class II transactivator (CIITA), allowing MM cells to escape from immunological responses. Here we demonstrate that a retinoic acid receptor-alpha/beta-selective retinoid Am80 (tamibarotene) could induce the expression of functional MHC II molecules in human MM cell lines. Am80 upregulated expression of the interferon regulatory factor-1 gene, followed by enhancement of CIITA expression. This is the first report demonstrating that retinoid can induce the expression of MHC II in terminally-differentiated plasma/MM cells. PMID:17229644

  20. Synthesis, characterization of complexes of Co(II), Ni(II), Cu(II) and Zn(II) with 12-membered Schiff base tetraazamacrocyclic ligand and the study of their antimicrobial and reducing power.

    PubMed

    Shakir, Mohammad; Azim, Yasser; Chishti, Hamida-Tun-Nisa; Parveen, Shama

    2006-10-01

    Schiff base tetraazamacrocyclic ligand, L (C(40)H(28)N(4)) and its complexes of types, [MLX(2)] and [CuL]X(2) (M=Co(II), Ni(II), Zn(II); X=Cl(-), NO(3)(-)) were synthesized and characterized by elemental analyses, mass, (1)H NMR, IR, UV-vis, magnetic susceptibility and molar conductance data. An octahedral geometry has been proposed for all the complexes except the copper(II) complexes which have a square planar environment. The reducing power of the Co(II) and Cu(II) complexes have been checked and compared. The ligand (L) and its complexes have also been screened against different fungi and bacteria in vitro. PMID:16522375

  1. Molecular and Structural Analysis of the Helicobacter pylori cag Type IV Secretion System Core Complex

    PubMed Central

    Frick-Cheng, Arwen E.; Pyburn, Tasia M.; Voss, Bradley J.; McDonald, W. Hayes

    2016-01-01

    ABSTRACT Bacterial type IV secretion systems (T4SSs) can function to export or import DNA, and can deliver effector proteins into a wide range of target cells. Relatively little is known about the structural organization of T4SSs that secrete effector proteins. In this report, we describe the isolation and analysis of a membrane-spanning core complex from the Helicobacter pylori cag T4SS, which has an important role in the pathogenesis of gastric cancer. We show that this complex contains five H. pylori proteins, CagM, CagT, Cag3, CagX, and CagY, each of which is required for cag T4SS activity. CagX and CagY are orthologous to the VirB9 and VirB10 components of T4SSs in other bacterial species, and the other three Cag proteins are unique to H. pylori. Negative stain single-particle electron microscopy revealed complexes 41 nm in diameter, characterized by a 19-nm-diameter central ring linked to an outer ring by spoke-like linkers. Incomplete complexes formed by Δcag3 or ΔcagT mutants retain the 19-nm-diameter ring but lack an organized outer ring. Immunogold labeling studies confirm that Cag3 is a peripheral component of the complex. The cag T4SS core complex has an overall diameter and structural organization that differ considerably from the corresponding features of conjugative T4SSs. These results highlight specialized features of the H. pylori cag T4SS that are optimized for function in the human gastric mucosal environment. PMID:26758182

  2. Kinetico-mechanistic Studies on the Substitution Reactivity on the {Ru(II)(bpy)2} Core with Nucleosides and Nucleotides at Physiological pH.

    PubMed

    Vázquez, Marta; Martínez, Manuel

    2016-07-01

    The kinetico-mechanistic study of the substitution reactions of the aquo ligands in cis-[Ru(bpy)2(H2O)2](2+) by different nucleotides and nucleosides has been conducted at pH close to the physiological value. The concentration dependence and thermal and pressure activation parameters have been measured to ascertain the activation via which reactions take place. Substitution processes are found associatively activated for nitrogen-bonded nucleosides or nucleotides, with outer-sphere hydrogen-bonded aggregates being determinant. For reactions leading to oxygen-bonded nucleotides, the process is clearly dissociatively activated. A selectively induced lability of the inert {Ru(II)(bpy)2} core is observed on the formation of nitrogen(amide)-bonded complexes at relatively low pH values, which might be relevant for the effective intercalation of designed, ruthenium(II)-bonded, aromatic rings. PMID:27327488

  3. 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.

  4. Synthesis, spectral characterization and catalytic activity of Co(II) complexes of drugs: Crystal structure of Co(II)-trimethoprim complex

    NASA Astrophysics Data System (ADS)

    Madhupriya, Selvaraj; Elango, Kuppanagounder P.

    2014-01-01

    New Co(II) complexes with drugs such as trimethoprim (TMP), cimetidine (CTD), niacinamide (NAM) and ofloxacin (OFL) as ligands were synthesized. The complexes were characterized by analytical analysis, various spectral techniques such as FT-IR, UV-Vis, magnetic measurements and molar conductivity. The magnetic susceptibility results coupled with the electronic spectra suggested a tetrahedral geometry for the complexes. The coordination mode of trimethoprim ligand and geometry of the complex were confirmed by single crystal X-ray studies. In this complex the metal ion possesses a tetrahedral geometry with two nitrogen atom from two TMP ligands and two chloride ions coordinated to it. The catalytic activity of the complexes in aryl-aryl coupling reaction was screened and the results indicated that among the four complexes [Co(OFL)Cl(H2O)] exhibited excellent catalytic activity.

  5. 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.

  6. Luminescent Silica Core / Silver Shell Encapsulated with Eu(III) Complex.

    PubMed

    Zhang, Jian; Fu, Yi; Lakowicz, Joseph R

    2009-11-12

    In this paper we studied the metal-enhanced emission from long-lifetime lanthanide dyes that were encapsulated in the silver nanoshells. The metal nanoshells were synthesized with the silica spherical cores of 50 nm diameters and the silver shells of 5 - 60 nm. The optical properties of luminescent metal shells were performed on the either ensemble fluorescence spectroscopy or single particle imaging. The emission intensity from the encapsulated lanthanides was observed to enhance significantly by the metal nanoshell. The enhancement efficiency initially increased with the metal shell thickness and then decreased. The maximal enhancement occurred at the 20 - 30 nm thickness. The lifetime of encapsulated Eu(III) complexes was shorten dramatically indicating that they were coupled efficiently with the metal shells. The increased brightness and reduced lifetime of this core-shell structure demonstrate that the lanthanides are favorable for the single target molecule detections after encapsulating into the metal nanoshells. PMID:20514146

  7. 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.

  8. Hydrogen peroxide generation by higher plant mitochondria oxidizing complex I or complex II substrates.

    PubMed

    Braidot, E; Petrussa, E; Vianello, A; Macri, F

    1999-05-28

    The generation of H2O2 by isolated pea stem mitochondria, oxidizing either malate plus glutamate or succinate, was examined. The level of H2O2 was almost one order of magnitude higher when mitochondria were energized by succinate. The succinate-dependent H2O2 formation was abolished by malonate, but unaffected by rotenone. The lack of effect of the latter suggests that pea mitochondria were working with a proton motive force below the threshold value required for reverse electron transfer. The activation by pyruvate of the alternative oxidase was reflected in an inhibition of H2O2 formation. This effect was stronger when pea mitochondria oxidized malate plus glutamate. Succinate-dependent H2O2 formation was ca. four times lower in Arum sp. mitochondria (known to have a high alternative oxidase) than in pea mitochondria. An uncoupler (FCCP) completely prevented succinate-dependent H2O2 generation, while it only partially (40-50%) inhibited that linked to malate plus glutamate. ADP plus inorganic phosphate (transition from state 4 to state 3) also inhibited the succinate-dependent H2O2 formation. Conversely, that dependent on malate plus glutamate oxidation was unaffected by low and stimulated by high concentrations of ADP. These results show that the main bulk of H2O2 is formed during substrate oxidation at the level of complex II and that this generation may be prevented by either dissipation of the electrochemical proton gradient (uncoupling and transition state 4-state 3), or preventing its formation (alternative oxidase). Conversely, H2O2 production, dependent on oxidation of complex I substrate, is mainly lowered by the activation of the alternative oxidase. PMID:10371218

  9. 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.

  10. Comparative study of copper(II)-curcumin complexes as superoxide dismutase mimics and free radical scavengers.

    PubMed

    Barik, Atanu; Mishra, Beena; Kunwar, Amit; Kadam, Ramakant M; Shen, Liang; Dutta, Sabari; Padhye, Subhash; Satpati, Ashis K; Zhang, Hong-Yu; Indira Priyadarsini, K

    2007-04-01

    Two stoichiometrically different copper(II) complexes of curcumin (stoichiometry, 1:1 and 1:2 for copper:curcumin), were examined for their superoxide dismutase (SOD) activity, free radical-scavenging ability and antioxidant potential. Both the complexes are soluble in lipids and DMSO. The formation constants of the complexes were determined by voltammetry. EPR spectra of the complexes in DMSO at 77K showed that the 1:2 Cu(II)-curcumin complex is square planar and the 1:1 Cu(II)-curcumin complex is distorted orthorhombic. Cu(II)-curcumin complex (1:1) with larger distortion from square planar structure shows higher SOD activity. These complexes inhibit gamma-radiation induced lipid peroxidation in liposomes and react with DPPH acting as free radical scavengers. One-electron oxidation of the two complexes by radiolytically generated azide radicals in Tx-100 micellar solutions produced phenoxyl radicals, indicating that the phenolic moiety of curcumin in the complexes participates in free radical reactions. Depending on the structure, these two complexes possess different SOD activities, free radical neutralizing abilities and antioxidant potentials. In addition, quantum chemical calculations with density functional theory have been performed to support the experimental observations. PMID:17240482

  11. 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. PMID:22935596

  12. Synthesis, characterization, equilibrium study and biological activity of Cu(II), Ni(II) and Co(II) complexes of polydentate Schiff base ligand

    NASA Astrophysics Data System (ADS)

    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]·nH2O, 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 Cu2+, Co2+ and Ni2+ 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 Cu2+, Ni2+ and Co2+ form 1:1 complexes.

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

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

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

  14. 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. PMID:26925968

  15. Metal based drugs: design, synthesis and in-vitro antimicrobial screening of Co(II), Ni(II), Cu(II) and Zn(II) complexes with some new carboxamide derived compounds: crystal structures of N-[ethyl(propan-2-yl)carbamothioyl]thiophene-2-carboxamide and its copper(II) complex.

    PubMed

    Sumrra, Sajjad H; Hanif, Muhammad; Chohan, Zahid H; Akram, Muhammad Safwan; Akhtar, Javeed; Al-Shehri, Saad M

    2016-08-01

    A new series of compounds derived from thiophene-2-carboxamide were synthesized and characterized by IR, (1)H-NMR and (13)C-NMR, mass spectrometry and elemental analysis. These compounds were further used to prepare their Co(II), Ni(II), Cu(II) and Zn(II) metal complexes. All metal(II) complexes were air and moisture stable. Physical, spectral and analytical data have shown the Ni(II) and Cu(II) complexes to exhibit distorted square-planar and Co(II) and Zn(II) complexes tetrahedral geometries. The ligand (L(1)) and its Cu(II) complex were characterized by the single-crystal X-ray diffraction method. All the ligands and their metal(II) complexes were screened for their in-vitro antimicrobial activity. The antibacterial and antifungal bioactivity data showed that the metal(II) complexes were found to be more potent than the parent ligands against one or more bacterial and fungal strains. PMID:26067080

  16. Electrocatalytic water oxidation using a chair-like tetranuclear copper(ii) complex in a neutral aqueous solution.

    PubMed

    Li, Ting-Ting; Zheng, Yue-Qing

    2016-08-01

    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. PMID:27445118

  17. 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.

  18. PHOTOLYSIS OF COPPER(II)-AMINO ACID COMPLEXES IN WATER

    EPA Science Inventory

    Kinetics of the photolysis of Cu2+-amino acid complexes were investigated under sunlight or monochromatic radiation. nder sunlight (latitude 40 degrees N) in the absence of dioxygen, the mean half-lives estimated for the photoreduction of the bis-Cu2+ complexes (CuL2) at pH 8.0 a...

  19. 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.

  20. Kinematic interpretation of the 3D shapes of metamorphic core complexes

    NASA Astrophysics Data System (ADS)

    Le Pourhiet, Laetitia; Huet, Benjamin; May, Dave A.; Labrousse, Loic; Jolivet, Laurent

    2012-09-01

    Metamorphic Core Complexes form dome shaped structures in which the ductile crust is exhumed beneath a detachment fault. The 3D dome geometry, inferred by mapping the schistosity in the exhumed crust, can be either elongated normal to the stretching direction or along it. In the first case, the domes are interpreted as having formed during extension. However, in the second case, they are interpreted either as strike-slip, transpressive or constrictive extensional structures, depending on the geodynamic context. Numerical models of metamorphic core complexes published to date are all two-dimensional and therefore, theoretically only apply to domes which are elongated normal to the stretching direction. Here, we explore by means of 3D thermomechanical modeling, the impact of 3D kinematic extensional boundary conditions on the shape of metamorphic core complexes. We examine the impact of a transtensional step over and of horsetail splay fault kinematics on the dynamics of exhumation, finite strain and P-T paths, and compare them to cylindrical 3D models. We show, for the first time, that domes formed in transtensional step over, or at the tip of propagating strike-slip faults, display a finite strain field which can be interpreted as characteristic of a transpressive domes, although no shortening was applied in the far-field. Applying our models to the Cyclades, we propose that the coeval formation of domes elongated normal and parallel to the stretching during the Miocene can be the result of horsetail splay fault kinematics, which could correspond to the formation of a tear in the Aegean slab.

  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. PMID:26021275

  2. Analysis of the NuRD subunits reveals a histone deacetylase core complex and a connection with DNA methylation

    PubMed Central

    Zhang, Yi; Ng, Huck-Hui; Erdjument-Bromage, Hediye; Tempst, Paul; Bird, Adrian; Reinberg, Danny

    1999-01-01

    ATP-dependent nucleosome remodeling and core histone acetylation and deacetylation represent mechanisms to alter nucleosome structure. NuRD is a multisubunit complex containing nucleosome remodeling and histone deacetylase activities. The histone deacetylases HDAC1 and HDAC2 and the histone binding proteins RbAp48 and RbAp46 form a core complex shared between NuRD and Sin3-histone deacetylase complexes. The histone deacetylase activity of the core complex is severely compromised. A novel polypeptide highly related to the metastasis-associated protein 1, MTA2, and the methyl-CpG-binding domain-containing protein, MBD3, were found to be subunits of the NuRD complex. MTA2 modulates the enzymatic activity of the histone deacetylase core complex. MBD3 mediates the association of MTA2 with the core histone deacetylase complex. MBD3 does not directly bind methylated DNA but is highly related to MBD2, a polypeptide that binds to methylated DNA and has been reported to possess demethylase activity. MBD2 interacts with the NuRD complex and directs the complex to methylated DNA. NuRD may provide a means of gene silencing by DNA methylation. PMID:10444591

  3. Anticancer activity and DNA-binding investigations of the Cu(II) and Ni(II) complexes with coumarin derivative.

    PubMed

    Zhu, Taofeng; Wang, Yuan; Ding, Weiliang; Xu, Jun; Chen, Ruhua; Xie, Jing; Zhu, Wenjiao; Jia, Lei; Ma, Tieliang

    2015-03-01

    Two new copper(II) (2) and nickel(II) (3) complexes with a new coumarin derivative have been synthesized and structurally characterized. The DNA-binding activities of the two complexes have been investigated by spectrometric titrations, ethidium bromide displacement experiments, CD (circular dichroism) spectral analysis, and viscosity measurements. The results indicate that the two complexes, especially the complex 2, can strongly bind to calf-thymus DNA (CT--DNA). The intrinsic binding constants Kb of the complexes with CT-DNA are 2.99 × 10(5) and 0.61 × 10(5) for 2 and 3, respectively. Comparative cytotoxic activities of the two complexes are also determined by MTT assay. The results show that the drugs designed here have significant cytotoxic activity against the human hepatic (HepG2), human promyelocytic leukemia (HL60), and human prostate (PC3) cell lines. Cell apoptosis was detected by Annexin V/PI flow cytometry, and the results show that the two copper complexes can induce apoptosis of the three human tumor cells. In conclusions, the two complexes show considerable cytotoxic activity against the three human cancer and induce apoptosis of the threes. PMID:25141910

  4. Synthesis, characterization, crystal structure and cytotoxic properties of thiosemicarbazide Ni(II) and Zn(II) complexes

    NASA Astrophysics Data System (ADS)

    Mathan Kumar, S.; Rajesh, J.; Anitha, K.; Dhahagani, K.; Marappan, M.; Indra Gandhi, N.; Rajagopal, G.

    2015-05-01

    Synthesis of new complexes of Ni(II) (1) and Zn(II) (2) with [1-(2-hydroxy-3,5-diiodobenzylidene)-4-phenylthiosemicarbazide] have been reported. The composition of these two complexes 1 and 2 is discussed on the basis of IR, 1H NMR and UV spectral data along with their X-ray crystallographic data. The crystal structure of these two complexes has revealed that the free ligand (L) is deprotonated twice at the oxygen and sulfur atoms and they are coordinated with the complexes through phenoxide-O, azomethine-N and thiolate-S atoms. The single-crystal X-ray structures of complex (1) exhibits a square planar structure, while complex (2) reveals trigonal bipyramidal distorted square based pyramidal structure. Anticancer activity of ligand and the complexes 1-2 are evaluated in human adenocarcinoma (MCF-7) cells. The preliminary bioassay indicates that the free ligand and the complexes 1-2 exhibit inhibitory activity against the human adenocarcinoma cancer cell lines.

  5. Synthesis, characterization, crystal structure and cytotoxic properties of thiosemicarbazide Ni(II) and Zn(II) complexes.

    PubMed

    Mathan Kumar, S; Rajesh, J; Anitha, K; Dhahagani, K; Marappan, M; Indra Gandhi, N; Rajagopal, G

    2015-05-01

    Synthesis of new complexes of Ni(II) (1) and Zn(II) (2) with [1-(2-hydroxy-3,5-diiodobenzylidene)-4-phenylthiosemicarbazide] have been reported. The composition of these two complexes 1 and 2 is discussed on the basis of IR, (1)H NMR and UV spectral data along with their X-ray crystallographic data. The crystal structure of these two complexes has revealed that the free ligand (L) is deprotonated twice at the oxygen and sulfur atoms and they are coordinated with the complexes through phenoxide-O, azomethine-N and thiolate-S atoms. The single-crystal X-ray structures of complex (1) exhibits a square planar structure, while complex (2) reveals trigonal bipyramidal distorted square based pyramidal structure. Anticancer activity of ligand and the complexes 1-2 are evaluated in human adenocarcinoma (MCF-7) cells. The preliminary bioassay indicates that the free ligand and the complexes 1-2 exhibit inhibitory activity against the human adenocarcinoma cancer cell lines. PMID:25706599

  6. 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

    2015-08-01

    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

  7. 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)

  8. Spectral studies of copper(II) complexes of 6-(3-thienyl) pyridine-2-thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Mahjoub, Omima Abdalla; Farina, Yang

    2014-09-01

    Two novel copper(II) complexes [Cu(HL)Cl]Cl˙H2O (1) and [Cu(L)NO3]˙H2O (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.

  9. An ethylene-glycol decorated ruthenium(ii) complex for two-photon photodynamic therapy.

    PubMed

    Boca, Sanda C; Four, Mickaël; Bonne, Adeline; van der Sanden, Boudewijn; Astilean, Simion; Baldeck, Patrice L; Lemercier, Gilles

    2009-08-14

    A novel water-soluble Ru(ii) complex has been prepared, which represents a promising new class of selective two-photon sensitizers for use in photodynamic therapy within a confined space. PMID:19617993

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Synthesis, characterization and in vitro antimicrobial studies of Co(II), Ni(II) and Cu(II) complexes derived from macrocyclic compartmental ligand.

    PubMed

    El-Gammal, O A; Bekheit, M M; El-Brashy, S A

    2015-02-25

    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, (1)H 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 Cu(2+) complex confirmed the suggested geometry with values of a α(2)and β(2) 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. PMID:25218230

  15. Complex formation equilibria of some beta-amino-alcohols with lead(II) and cadmium(II) in aqueous solution.

    PubMed

    Canepari, S; Carunchio, V; Castellano, P; Messina, A

    1998-12-01

    A study of complex formation equilibria of some beta-amino-alcohols with lead(II) and cadmium(II) ions at 25 degrees C and in 0.5 M KNO(3) is reported. The amino-alcohols considered are 2-amino-1-propanol, 2-amino-1-butanol, 2-amino-1-pentanol and 2-amino-1,3-propanediol. sec-Buthylamine and 2-amino-1-methoxy-propane have been also considered for comparison. The results are discussed in terms of ligand structure, paying attention to the number of hydroxyl groups and to the length of the alkyl residual. A weak contribution of the alcoholic oxygen in the coordination of cadmium(II) and the presence of a mixed hydroxyl species in lead(II) containing systems are hypothesized. PMID:18967412

  16. Synthesis and spectroscopic studies on the Schiff base ligand derived from condensation of 2-furaldehyde and 3,3'-diaminobenzidene, L and its complexes with Co(II), Ni(II), Cu(II) and Zn(II): Comparative DNA binding studies of L and its Cu(II) and Zn(II) complexes

    NASA Astrophysics Data System (ADS)

    Shakir, Mohammad; Abbasi, Ambreen; Khan, Asad U.; Khan, Shahper N.

    2011-01-01

    The Schiff base ligand, N,N'-bis-(2-furancarboxaldimine)-3,3'-diaminobenzidene (L) obtained by condensation of 2-furaldehyde and 3,3'-diaminobenzidene, was used to synthesize the mononuclear complexes of the type, [M(L)](NO 3) 2 [M = Co(II), Ni(II), Cu(II) and Zn(II)]. The newly synthesized ligand, (L) and its complexes have been characterized on the basis of the results of the elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz, FT-IR, 1H and 13C NMR, mass, UV-vis and EPR. EPR, UV-vis and magnetic moment data revealed a square planar geometry for the complexes with distortion in Cu(II) complex and conductivity data show a 1:2 electrolytic nature of the complexes. Absorption and fluorescence spectroscopic studies support that Schiff base ligand, L and its Cu(II) and Zn(II) complex exhibit significant binding to calf thymus DNA. The highest binding affinity in case of L may be due to the more open structure as compared to the metal coordinated complexes.

  17. Structure studies of Ni(II) complexes with picolinaldehyde N-oxide thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Qing, Yu; Hua, Deng Ji; Gang, Zhu Li; Qing, Zhang Xiu; Dong, Bian He; Hong, Liang

    2006-08-01

    Two nickel(II) complexes [Ni(Hpiotsc) 2(NO 3) 2] ( 1), [Ni(Hpiotsc) 2(NO 3) 2]·H 2O ( 2) were synthesized and characterized by single crystal X-ray diffraction, IR, and thermal analyses. The geometry of the nickel(II) atom in two complexes is a distorted octahedron with ONS atoms of two neutral ligands. The antimicrobial activities of complex 1 were evaluated by the MIC (minimum inhibitory concentration) against five bacteria. The six-coordinate complex 1 did not inhibit the growth of the test organisms.

  18. EPR, mass, IR, electronic, and magnetic studies on copper(II) complexes of semicarbazones and thiosemicarbazones

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Gupta, Lokesh Kumar

    2005-01-01

    Copper(II) complexes having the general composition Cu(L) 2X 2 [where L = isopropyl methyl ketone semicarbazone (LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC), and 4-aminoacetophenone thiosemicarbazone (LLD) and X = Cl -, 1/2SO 42-] have been synthesized. All the Cu(II) complexes reported here have been characterized by elemental analyses, molar conductance, magnetic moment susceptibility, EI mass, 1H NMR, IR, EPR, and electronic spectral studies. All the complexes were found to have magnetic moments corresponding to one unpaired electrons. The possible geometries of the complexes were assigned on the basis of EPR, electronic, and infrared spectral studies.

  19. Studies on some salicylaldehyde Schiff base derivatives and their complexes with Cr(III), Mn(II), Fe(III), Ni(II) and Cu(II).

    PubMed

    Abdel-Latif, S A; Hassib, H B; Issa, Y M

    2007-07-01

    The formation constants of some transition metal ions Cr(III), Mn(II), Fe(III), Ni(II) and Cu(II) binary complexes containing Schiff bases resulting from condensation of salicylaldehyde with aniline (I), 2-aminopyridine (II), 4-aminopyridine (III) and 2-aminopyrimidine (IV) were determined pH-metrically in ethanolic medium (80%, v/v). The formation constants were determined for all binary complexes. The important infrared (IR) spectral bands corresponding to the active groups in the four ligands and the solid complexes under investigation were studied. The solid complexes have been synthesized and studied by thermogravimetric analysis. The thermal dehydration and decomposition of these complexes were studied kinetically using the integral method applying the Coats-Redfern equation. It was found that the thermal decomposition of the complexes follow second order kinetics. The thermodynamic parameters of the decomposition are also reported. The electronic absorption spectra of the investigated ligands were carried out to determine the pK(a) values spectrophotometrically. PMID:17084104

  20. Studies on some salicylaldehyde Schiff base derivatives and their complexes with Cr(III), Mn(II), Fe(III), Ni(II) and Cu(II)

    NASA Astrophysics Data System (ADS)

    Abdel-Latif, S. A.; Hassib, H. B.; Issa, Y. M.

    2007-07-01

    The formation constants of some transition metal ions Cr(III), Mn(II), Fe(III), Ni(II) and Cu(II) binary complexes containing Schiff bases resulting from condensation of salicylaldehyde with aniline (I), 2-aminopyridine (II), 4-aminopyridine (III) and 2-aminopyrimidine (IV) were determined pH-metrically in ethanolic medium (80%, v/v). The formation constants were determined for all binary complexes. The important infrared (IR) spectral bands corresponding to the active groups in the four ligands and the solid complexes under investigation were studied. The solid complexes have been synthesized and studied by thermogravimetric analysis. The thermal dehydration and decomposition of these complexes were studied kinetically using the integral method applying the Coats-Redfern equation. It was found that the thermal decomposition of the complexes follow second order kinetics. The thermodynamic parameters of the decomposition are also reported. The electronic absorption spectra of the investigated ligands were carried out to determine the p Ka values spectrophotometrically.

  1. Synthesis, magnetic, spectral, and antimicrobial studies of Cu(II), Ni(II) Co(II), Fe(III), and UO 2(II) complexes of a new Schiff base hydrazone derived from 7-chloro-4-hydrazinoquinoline

    NASA Astrophysics Data System (ADS)

    El-Behery, Mostafa; El-Twigry, Haifaa

    2007-01-01

    A new hydrazone ligand, HL, was prepared by the reaction of 7-chloro-4-hydrazinoquinoline with o-hydroxybenzaldehyde. The ligand behaves as monoprotic bidentate. This was accounted for as the ligand contains a phenolic group and its hydrogen atom is reluctant to be replaced by a metal ion. The ligand reacted with Cu(II), Ni(II), Co(II), Fe(III), and UO 2(II) ions to yield mononuclear complexes. In the case of Fe(III) ion two complexes, mono- and binuclear complexes, were obtained in the absence and presence of LiOH, respectively. Also, mixed ligand complexes were obtained from the reaction of the metal cations Cu(II), Ni(II) and Fe(III) with the ligand (HL) and 8-hydroxyquinoline (8-OHqu) in the presence of LiOH, in the molar ratio 1:1:1:1. It is clear that 8-OHqu behaves as monoprotic bidentate ligand in such mixed ligand complexes. The ligand, HL, and its metal complexes were characterized by elemental analyses, IR, UV-vis, mass, and 1H NMR spectra, as well as magnetic moment, conductance measurements, and thermal analyses. All complexes have octahedral configurations except Cu(II) complex which has an extra square-planar geometry, while Ni(II) mixed complex has also formed a tetrahedral configuration and UO 2(II) complex which formed a favorable pentagonal biprymidial geometry. Magnetic moment of the binuclear Fe(III) complex is quite low compared to calculated value for two iron ions complex and thus shows antiferromagnetic interactions between the two adjacent ferric ions. The HL and metal complexes were tested against one stain Gram positive bacteria ( Staphylococcus aureus), Gram negative bacteria ( Escherichia coli), and fungi ( Candida albicans). The tested compounds exhibited higher antibacterial acivities.

  2. Crystal structures of copper(II) chloride, copper(II) bromide, and copper(II) nitrate complexes with pyridine-2-carbaldehyde thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Chumakov, Yu. M.; Tsapkov, V. I.; Jeanneau, E.; Bairac, N. N.; Bocelli, G.; Poirier, D.; Roy, J.; Gulea, A. P.

    2008-09-01

    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 10-5 mol/l selectively inhibit the growth of 60 to 90 percent of the cancer tumor cells of the human myeloid leukemia (HL-60).

  3. 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).

  4. The EARP Complex and Its Interactor EIPR-1 Are Required for Cargo Sorting to Dense-Core Vesicles.

    PubMed

    Topalidou, Irini; Cattin-Ortolá, Jérôme; Pappas, Andrea L; Cooper, Kirsten; Merrihew, Gennifer E; MacCoss, Michael J; Ailion, Michael

    2016-05-01

    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

  5. 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

  6. Voltammetric Characterization of Cu(II) Complexation in Real-Time.

    PubMed

    Siriwardhane, Thushani; Sulkanen, Audrey; Pathirathna, Pavithra; Tremonti, Annette; McElmurry, Shawn P; Hashemi, Parastoo

    2016-08-01

    Aqueous metal behavior is strongly regulated by speciation, which in turn is highly dependent on complexation. Trace metal complexation is difficult to characterize in dynamically changing systems due to a lack of analytical methods that can rapidly report free-metal concentrations. In this paper, we perform proof-of-principle experiments that demonstrate the utility of fast-scan cyclic voltammetry (FSCV) for providing speciation information in real-time by characterizing dynamic Cu(II) binding. We study Cu(II) FSCV responses in 3-(N-morpholino)propanesulfonic acid (MOPS) buffer and characterize the hydrodynamic aspects of our experimental setup (continuously stirred tank reactor). We observe Cu(II) complexation in real-time using five ligands with differing formation constants of Cu(II) complexation. Finally, we utilize geochemical models to fit our real-time experimental Cu(II)-binding curves. Our proof-of-principle experiments show that FSCV is a powerful tool for studying real-time Cu(II) complexation, which is essential speciation information for better interpretation of Cu(II) behavior in dynamically changing systems, such as those encountered in biology or the environment. PMID:27322355

  7. Spectroscopic characterization of copper(II) complexes of indoxyl N(4)-methyl thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Kumar, Umendra

    2004-10-01

    New copper(II) complexes of indoxyl thiosemicarbazone (ITSC) of general composition CuL 2X 2 (where L: ITSC; X: Cl -, NO 3-, ClO 4-, NCS -) have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility measurements and spectral (electronic, IR, EPR, 1H NMR , Mass) studies. Cyclic voltammetry measurements show quasi-reversible Cu 2+/Cu 1+ couple. Various physico-chemical techniques suggest a tetragonal structure for these copper(II) complexes.

  8. IR and ESR studies on novel Cu(II) theophyllinato complexes containing mono- or bidentate ligands

    NASA Astrophysics Data System (ADS)

    Forizs, Edit; David, L.; Cozar, O.; Chiş, V.; Damian, G.; Csibi, Jolán

    1999-05-01

    Three mixed-ligand copper(II) complexes containing theophylline and mono- or bidentate N-donor ligands (2,2'-bipyridine, 4-fluoraniline and 1,10-phenanthroline) were synthesized and characterized by elemental analysis, IR and ESR spectra. According to IR and ESR data the Cu(II) complexes exhibit a distorted tetrahedral coordination of copper by two nitrogen atoms of the monodentate or bidentate ligands and the two monodentate theophyllinate anion bonded through N(7) atom.

  9. 2-Benzoylpyridine thiosemicarbazone as a novel reagent for the single pot synthesis of dinuclear Cu(I)-Cu(II) complexes: formation of stable copper(II)-iodide bonds.

    PubMed

    Lobana, Tarlok S; Khanna, Sonia; Butcher, Ray J

    2012-04-28

    2-Benzoylpyridine thiosemicarbazone {R(1)R(2)C(2)=N(2)·N(3)H-C(1)(=S)-N(4)H(2), R(1) = py-N(1), R(2) = Ph; Hbpytsc} with copper(I) iodide in acetonitrile-dichloromethane mixture has formed stable Cu(II)-I bonds in a dark green Cu(II) iodo-bridged dimer, [Cu(2)(II)(μ-I)(2)(η(3)-N(1),N(2),S-bpytsc)(2)] 1. Copper(I) bromide also formed similar Cu(II)-Br bonds in a dark green Cu(II) bromo-bridged dimer, [Cu(2)(II)(μ-Br)(2)(η(3)-N(1),N(2),S-bpytsc)(2)] 3. The formation of dimers 1 and 3 appears to be due to a proton coupled electron transfer (PCET) process wherein copper(I) loses an electron to form copper(II), and this is accompanied by a loss of -N(3)H proton of Hbpytsc ligand resulting in the formation of anionic bpytsc(-). When copper(I) iodide was reacted with triphenylphosphine (PPh(3)) in acetonitrile followed by the addition of 2-benzoylpyridine thiosemicarbazone in dichloromethane (Cu : PPh(3) : Hbpytsc in the molar ratio 1:1:1), both Cu(II) dimer 1 and an orange Cu(I) sulfur-bridged dimer, [Cu(2)(I)I(2)(μ-S-Hbpytsc)(2)(PPh(3))(2)] 2 were formed. Copper(I) bromide with PPh(3) and Hbpytsc also formed Cu(II) dimer 3 and an orange Cu(I) sulfur-bridged dimer, [Cu(2)(I)Br(2)(μ-S-Hbpytsc)(2)(PPh(3))(2)] 4. While complexes 2 and 4 exist as sulfur-bridged Cu(I) dimers, 1 and 3 are halogen-bridged. The central Cu(2)S(2) cores of 2 and 4 as well as Cu(2)X(2) of 1 (X = I) and 3 (X = Br) are parallelograms. One set of Cu(II)-I and Cu(II)-Br bonds are short, while the second set is very long {1, Cu-I, 2.565(1), 3.313(1) Å; 3, Cu-Br, 2.391(1), 3.111(1) Å}. The Cu···Cu separations are long in all four complexes {1, 4.126(1); 2, 3.857(1); 3, 3.227(1); 4, 3.285(1) Å}, more than twice the van der Waals radius of a Cu atom, 2.80 Å. The pyridyl group appears to be necessary for stabilizing the Cu(II)-I bond, as this group can accept π-electrons from the metal. PMID:22395858

  10. 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.

  11. 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.

  12. 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.

  13. Infrared and Raman spectra of ethylene trithiocarbonate complexes of some Zn(II), Cd(II) and Hg(II) halides

    NASA Astrophysics Data System (ADS)

    Contreras, J. Guillermo; Gnecco, Juan A.

    Coordination compounds of ethylene trithiocarbonate (ETTC) with some Zn(II), Cd(II) and Hg(II) halides have been prepared, characterized and their infrared and Raman spectra recorded. The i.r. spectra in the range 4000-400 cm -1 suggest that the organic ligand is bonded to the metal ions through its exocyclic sulphur atom, whereas the far-i.r. and Raman spectra show that the complexes of the type HgX 2(ETTC) (X = Cl, Br or I) possess a trans dimeric halogen-bridged structure. The Cd(II) and Zn(II) species are of the type MX 2(ETTC) 2 and they possess a pseudotetrahedral structure of C2υ symmetry.

  14. Synthesis of thin film containing 4-amino-1,2,4-triazole iron(II) complexes

    NASA Astrophysics Data System (ADS)

    Onggo, Djulia

    2014-03-01

    The Iron(II) complex with 4-amino-1,2,4 triazole (NH2-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 NH2-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(NH2trz)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(NH2trz)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.

  15. 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.

  16. 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)

  17. Electron crystal structure of the transcription factor and DNA repair complex, core TFIIH.

    PubMed

    Chang, W H; Kornberg, R D

    2000-09-01

    Core TFIIH from yeast, made up of five subunits required both for RNA polymerase II transcription and nucleotide excision DNA repair, formed 2D crystals on charged lipid layers. Diffraction from electron micrographs of the crystals in negative stain extended to about 13 angstrom resolution, and 3D reconstruction revealed several discrete densities whose volumes corresponded well with those of individual TFIIH subunits. The structure is based on a ring of three subunits, Tfb1, Tfb2, and Tfb3, to which are appended several functional moieties: Rad3, bridged to Tfb1 by SsI1; SsI2, known to interact with Tfb2; and Kin28, known to interact with Tfb3. PMID:11007479

  18. SnapShot: SMC Protein Complexes Part II.

    PubMed

    Haering, Christian H; Gruber, Stephan

    2016-02-11

    This second of two SnapShots on SMC proteins depicts their roles at different stages of the eukaryotic cell cycle. The composition and architecture of SMC protein complexes and their regulators appear in SMC Protein Complexes Part I (available at http://www.cell.com/cell/pdf/S0092-8674%2815%2901690-6.pdf). To view this SnapShot, open or download the PDF. PMID:26871638

  19. Photocatalytic hydrogen evolution by Cu(ii) complexes.

    PubMed

    Wang, Junfei; Li, Chao; Zhou, Qianxiong; Wang, Weibo; Hou, Yuanjun; Zhang, Baowen; Wang, Xuesong

    2016-04-01

    [Cu(TMPA)Cl]Cl (1) and [Cu(Cl-TMPA)Cl2] (2) exhibited efficient photocatalytic H2 evolution with a TON of 6108 and 10014 (6 h), respectively, in CH3CN/H2O solution (9 : 1, v/v) containing an Ir complex as the photosensitizer and triethylamine as the sacrificial reductant, representing the first example of photocatalytic Cu complex-based water reduction catalysts. PMID:26959193

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

    SciTech Connect

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

    1986-08-01

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

  1. Architecture of the S. cerevisiae RNA polymerase I Core Factor complex

    PubMed Central

    Knutson, Bruce A.; Luo, Jie; Ranish, Jeffrey; Hahn, Steven

    2014-01-01

    Core Factor (CF) is a conserved RNA polymerase (Pol) I general transcription factor and is comprised of Rrn6, Rrn11, and the TFIIB-related subunit Rrn7. CF binds TBP, Pol I, and the regulatory factors Rrn3 and UAF. We used chemical crosslinking-mass spectrometry (CXMS) to determine the molecular architecture of CF and its interactions with TBP. The CF subunits assemble through an interconnected network of interactions between five structural domains that are conserved in orthologous subunits of the human Pol I factor SL1. The crosslinking-derived model was validated through a series of genetic and biochemical assays. Our combined results show the architecture of CF and the functions of the CF subunits in assembly of the complex. We extend these findings to model how CF assembles into the Pol I preinitiation complex, providing new insight into the roles of CF, TBP and Rrn3. PMID:25132180

  2. Evolution of complex organic molecules in hot molecular cores. Synthetic spectra at (sub-)mm wavebands

    NASA Astrophysics Data System (ADS)

    Choudhury, R.; Schilke, P.; Stéphan, G.; Bergin, E.; Möller, T.; Schmiedeke, A.; Zernickel, A.

    2015-03-01

    Context. Hot molecular cores (HMCs) are intermediate stages of high-mass star formation and are also known for their rich chemical reservoirs and emission line spectra at (sub-)mm wavebands. Complex organic molecules (COMs) such as methanol (CH3OH), ethanol (C2H5OH), dimethyl ether (CH3OCH3), and methyl formate (HCOOCH3) produce most of these observed lines. The observed spectral feature of HMCs such as total number of emission lines and associated line intensities are also found to vary with evolutionary stages. Aims: We aim to investigate the spectral evolution of these COMs to explore the initial evolutionary stages of high-mass star formation including HMCs. Methods: We developed various 3D models for HMCs guided by the evolutionary scenarios proposed by recent empirical and modeling studies. We then investigated the spatio-temporal variation of temperature and molecular abundances in HMCs by consistently coupling gas-grain chemical evolution with radiative transfer calculations. We explored the effects of varying physical conditions on molecular abundances including density distribution and luminosity evolution of the central protostar(s) among other parameters. Finally, we simulated the synthetic spectra for these models at different evolutionary timescales to compare with observations. Results: Temperature has a profound effect on the formation of COMs through the depletion and diffusion on grain surface to desorption and further gas-phase processing. The time-dependent temperature structure of the hot core models provides a realistic framework for investigating the spatial variation of ice mantle evaporation as a function of evolutionary timescales. We find that a slightly higher value (15 K) than the canonical dark cloud temperature (10 K) provides a more productive environment for COM formation on grain surface. With increasing protostellar luminosity, the water ice evaporation font (~100 K) expands and the spatial distribution of gas phase abundances of

  3. [Effective core formulae for lung cancer based on complex network and survival analysis].

    PubMed

    Yang, Ming; Li, Jia-qi; Jiao, Li-jing; Chen, Pei-qi; Xu, Ling

    2015-11-01

    The study on the effective core formulae (CEF) not only summarized traditional chinese medicine (TCM) treatment experience, but also helped reveal the underlying knowledge in the formulation of TCM prescriptions. The aim of the present paper was to investigate the method of data mining for the discovery of core effective formulae for lung cancer. In the present study, a prescription fingerprint approach was used to characterize the staged prescription information of patients. The D index was used to screen potential beneficial herbs. Then, based on a herbal compatibility network, the maximal clique searching algorithm (BK algorithm) and survival analysis were applied to discover CEF for lung cancer, and a mining analysis was made for the 322 cases from Longhua hospital. The correlation between prescriptions and survival time was analyzed by prescription fingerprints. Forty-three potentially beneficial herbs were obtained, and two CEFs were significant for the survival time by a parametric survival model based on lognormal distribution, the results were verified by a multivariate survival model. The rules of combination of the two CEFs basically conform to TCM onco-therapeutic theory of strengthening the body resistance and the actual conditions in clinic. All results showed that the established approach was feasible for discovering the core effective formulae for lung cancer and mining survival data for complex TCM onco-therapy. PMID:27097428

  4. 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.

  5. 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

  6. 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.

  7. Optical phonon modes of III-V nanoparticles and indium phosphide/II-VI core-shell nanoparticles: A Raman and infrared study

    NASA Astrophysics Data System (ADS)

    Manciu, Felicia Speranta

    The prospects for realizing efficient nanoparticle light emitters in the visible/near IR for communications and bio-medical applications have benefited from progress in chemical fabrication of nanoparticles. III-V semiconductor nanopaticles such as GaP and InP are promising materials for the development of "blue" and "green" emitters, respectively, due to their large effective bandgaps. Enhanced emission efficiency has been achieved for core-shell nanoparticles, since inorganic shell materials increase electronic tunability and may decrease surface defects that often occur for nanoparticles capped with organic molecules. Also, the emission wavelength of InP nanoparticle cores can be tuned from green to red by changing the shell material in InP/II-VI core-shell nanoparticles. Investigations of phonon modes in nanocrystals are of both fundamental and applied interest. In the former case the optical phonon modes, such as surface/interface modes, are dependent on the nanoparticle dimensions, and also can provide information about dynamical properties of the nanoparticles and test the validity of various theoretical approaches. In the latter case the vibronic properties of nanoparticle emitters are controlled by confined phonons and modifications of the electron-phonon interaction by the confinement. Thus, the objective of the present thesis is the detailed study of the phonon modes of III-V nanoparticles (GaP and InP) and InP/II-VI core-shell nanoparticles by IR absorption and Raman scattering spectroscopies, and an elucidation of their complex vibrational properties. With the exception of three samples (two GaP and one InP), all samples were synthesized by a novel colloidal chemistry method, which does not requires added surfactant, but rather treatment of the corresponding precursors in octadecene noncoordinative solvent. Sample quality was characterized by ED, TEM and X-ray diffraction. Based on a comparison with a dielectric continuum model, the observed features

  8. BSA binding and antimicrobial studies of branched polyethyleneimine-copper(II)bipyridine/phenanthroline complexes

    NASA Astrophysics Data System (ADS)

    Vignesh, Gopalaswamy; Arunachalam, Sankaralingam; Vignesh, Sivanandham; James, Rathinam Arthur

    2012-10-01

    The interaction of two water soluble branched polyethyleneimine-copper(II) complexes containing bipyridine/phenanthroline with bovine serum albumin (BSA) was studied by, UV-Visible absorption, fluorescence, lifetime measurements and circular dichroism spectroscopic techniques. The polymer-copper(II) complexes strongly quench the intrinsic fluorescence of BSA is the static quenching mechanism through hydrogen bonds and van der Waal's attraction. The distance r, between the BSA and the complexes seems to be less than 2 nm indicating that the energy transfer between the donor and acceptor occurs with high probability. Synchronous fluorescence studies indicate the binding of polymer-copper(II) complexes with BSA mostly changes the polarity around tryptophan residues rather than tyrosine residues. The circular dichroism studies indicate that the binding has induced considerable amount of conformational changes in the protein. The complexes also show some antibacterial and antifungal properties.

  9. Spectroscopic, thermal and electrochemical studies on some nickel(II) thiosemicarbazone complexes

    NASA Astrophysics Data System (ADS)

    El-Shazly, R. M.; Al-Hazmi, G. A. A.; Ghazy, S. E.; El-Shahawi, M. S.; El-Asmy, A. A.

    2005-01-01

    Several complexes of thiosemicarbazone derivatives with Ni(II) have been prepared. Structural investigation of the ligands and their complexes has been made based on elemental analysis, magnetic moment, spectral (UV-Vis, i.r., 1H NMR, ms), and thermal studies. The i.r. spectra suggest the bidentate mononegative and tridentate (neutral, mono-, and binegative) behavior of the ligands. Different stereochemistries were suggested for the isolated complexes. The thermogravimetry (TG) and derivative thermogravimetry (DTG) have been used to study the thermal decomposition and kinetic parameters of some ligands and complexes using the Coats-Redfern and Horowitz-Metzger equations. The redox properties and stability of the complexes toward oxidation waves explored by cyclic voltammetry are related to the electron withdrawing or releasing ability of the substituent of thiosemicarbazone moiety. The samples displayed Ni II/Ni I couples irreversible waves associated with Ni III/Ni II process.

  10. Synthesis and Antiproliferative Activity of Steroidal Thiosemicarbazone Platinum (Pt(II)) Complexes.

    PubMed

    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

  11. 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

  12. Spectroscopic and biological studies on newly synthesized nickel(II) complexes of semicarbazones and thiosemicarbazones

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Gupta, Lokesh Kumar

    2005-12-01

    Nickel(II) complexes, having the general composition Ni(L) 2X 2, have been synthesized [where L: isopropyl methyl ketone semicarbazone (LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC) and 4-aminoacetophenone thiosemicarbazone (LLD) and X = Cl -, 1/2SO 42-]. All the Ni(II) complexes reported here have been characterized by elemental analyses, magnetic moments, IR, electronic and mass spectral studies. All the complexes were found to have magnetic moments corresponding to two unpaired electrons. The possible geometries of the complexes were assigned on the basis of electronic and infrared spectral studies. Newly synthesized ligand and its nickel(II) complexes have been screened against different bacterial and fungal growth.

  13. Supramolecular assemblies with calix[6]arenes and copper ions: from dinuclear to trinuclear linear arrangements of hydroxo-Cu(II) complexes.

    PubMed

    Izzet, Guillaume; Akdas, Huriye; Hucher, Nicolas; Giorgi, Michel; Prangé, Thierry; Reinaud, Olivia

    2006-02-01

    Complexation of copper(II) by calix[6]arene-based ligands bearing either two or three N-benzylimidazole coordinating arms under basic conditions has been studied. Whereas the tris(imidazole) derivative stabilizes dicationic 5-coordinate aqua complexes in a mononuclear state with an intracavity bound guest, in the presence of hydroxide ions, the latter undergo dimerization. An X-ray structure revealed decoordination of one imidazole arm and formation of a bis(hydroxo) bridged Cu(II) core with a square-planar geometry for both metal centers sandwiched by two empty calixarene cavities. Upon methanolysis, the dinuclear complex underwent an unexpected rearrangement leading to the clean formation of a trinuclear complex. X-ray diffraction analyses of this novel species revealed a trinuclear core constructed around a central Cu(II) ion that is doubly bridged through either methoxide or hydroxide anions to two Cu(II) ions hold by two calixarene units. The same complex could be directly synthesized by reacting the ligand with copper(II) perchlorate in a 2:3 ratio in the presence of base. In solution, the tetrahydroxo Cu(3) complex was characterized by UV-vis and (1)H NMR spectroscopies and displayed an electron paramagnetic resonance (EPR) signal only below 100 K that accounts for a S = 1/2 fundamental state. Formation of the same di- and trinuclear species was observed with a calix[6]arene-based bis(imidazole) ligand, which demonstrates the generality of the reaction schemes. All these results emphasize the versatility of the calix[6]arene scaffold for the stabilization of metal complexes with various nuclearities. PMID:16441115

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  15. Time and duration of metamorphism and exhumation of the central Rhodopian core complex, Bulgaria

    NASA Astrophysics Data System (ADS)

    Ovtcharova, M.; von Quadt, A.; Peytcheva, I.; Neubauer, F.; Heinrich, C. A.; Kaiser, M.

    2003-04-01

    The evolution of central Rhodopian dome (Bulgaria) is interpreted in terms of an extensional collapse of thickened crust (Ivanov at al., 2000). U-Pb isotope dating (single Zr and Mnz), Rb-Sr (W.R., Bt and Ap) and Ar-Ar (on Bt) were carried out on different rocks from the central Rhodope, Bulgaria, to constrain the timing and duration of the metamorphism and exhumation of the core complex. The beginning of extensional stage is marked by intrusion of earliest non-penetratively deformed granite bodies at 53Ma (U-Pb on single Zr and Mnz). The late Alpine extensional evolution of the massif is marked by a detachment system connected with exhumation of the migmatites in the core part of the dome (lower plate). U-Pb analyses on Mnz and Zr from mesosome and discordant leucosome yield a Variscan protolith age of the gneiss (311 Ma) and Eocene age (37Ma) of crystallization of the newly formed anatectic melt that corresponds with the peak of the Alpine metamorphic event (P 4.5-6kbar and T 720-750^oC; Georgieva et al., 2002). Rb-Sr mineral system of the weakly deformed gneisses from lower plate of the core complex gives evidence for a cooling age of 34.5±0.34Ma. This result is confirmed by Ar-Ar on Bt from the same rock: 35.5±0.4Ma. Ar-Ar data on biotite from gneisses of the upper plate yield an age of 34.9±0.6Ma. The same age is reflected by an Rb-Sr isochron (W.R., Bt and Ap) of 35.22±0.35Ma. The post-collisional extension was followed by graben depressions filled with sediments of Eocene-Oligocene age and active volcanism and ore mineralization (Zn-Pb and Cu-Pb-Zn ore deposits). Connected with the most intensively "stretched" sections of the extensional system is emplacement of rhyolitic dikes at 32.8±0.41Ma (U-Pb on single Zr, Xe). The available data constrain narrow time bracket between timing of high-grade metamorphism event (37Ma, >600^oC), cooling (35Ma, 300ºC) of the core complex and volcanic activity (32Ma) that corresponds with rapid exhumation tectonic regime

  16. DNA Binding, Cleavage and Antibacterial Activity of Mononuclear Cu(II), Ni(II) and Co(II) Complexes Derived from Novel Benzothiazole Schiff Bases.

    PubMed

    Vamsikrishna, Narendrula; Kumar, Marri Pradeep; Tejaswi, Somapangu; Rambabu, Aveli; Shivaraj

    2016-07-01

    A series of novel bivalent metal complexes M(L1)2 and M(L2)2 where M = Cu(II), Ni(II), Co(II) and L1 = 2-((benzo [d] thiazol-6-ylimino)methyl)-4-bromophenol [BTEMBP], L2 = 1-((benzo [d] thiazol-6-ylimino)methyl) naphthalen-2-ol [BTEMNAPP] were synthesized. All the compounds have been characterized by elemental analysis, SEM, Mass, (1)H NMR, (13)C NMR, UV-Vis, IR, ESR, spectral data and magnetic susceptibility measurements. Based on the analytical and spectral data four-coordinated square planar geometry is assigned to all the complexes. DNA binding properties of these complexes have been investigated by electronic absorption spectroscopy, fluorescence and viscosity measurements. It is observed that these binary complexes strongly bind to calf thymus DNA by an intercalation mode. DNA cleavage efficacy of these complexes was tested in presence of H2O2 and UV light by gel electrophoresis and found that all the complexes showed better nuclease activity. Finally the compounds were screened for antibacterial activity against few pathogens and found that the complexes have potent biocidal activity than their free ligands. PMID:27165038

  17. Structural studies and photochromism of mercury(II)-iodo complexes of (arylazo)imidazoles.

    PubMed

    Sarker, K K; Chand, B G; Suwa, K; Cheng, J; Lu, T-H; Otsuki, J; Sinha, C

    2007-02-01

    Neat reaction between HgI2 and 1-methyl-2-(phenylazo)imidazole (Pai-Me) under microwave irradiation has isolated a novel compound whose structure shows intercalated HgI2 in the layers of Pai-Me. They exist independently in interpenetrated arrays. In a solution phase study, the same reaction has synthesized an iodo-bridged azoimidazole-Hg(II) complex, [Hg(RaaiR')(mu-I)(I)]2 (RaaiR' = 1-alkyl-2-(arylazo)imidazole). The structures have been characterized by X-ray diffraction studies. Chloro-bridged Hg(II) complexes of azoimidazoles, [Hg(RaaiR')(mu-Cl)(Cl)]2, are also known. These complexes upon irradiation with UV light show trans-to-cis isomerization. The reverse transformation, cis-to-trans isomerization, is very slow with visible light irradiation. Quantum yields (phi t-->c) of trans-to-cis isomerization are calculated, and the free ligand shows higher phi than their Hg(II) complexes. The cis-to-trans isomerization is a thermally induced process. The activation energy (Ea) of cis-to-trans isomerization is calculated by controlled temperature reaction. The Ea's of free ligands are much higher than that of halo-bridged Hg(II)-azoimidazole complexes. Chloro-bridged Hg(II) complexes show lower Ea's than those of iodo-bridged complexes. DFT calculation has been adopted to rationalize the experimental results. PMID:17257009

  18. Multinuclear NMR spectroscopy and antiproliferative activity in vitro of platinum(II) and palladium(II) complexes with 6-mercaptopurine

    NASA Astrophysics Data System (ADS)

    Łakomska, Iwona; Pazderski, Leszek; Sitkowski, Jerzy; Kozerski, Lech; Pełczyńska, Marzena; Nasulewicz, Anna; Opolski, Adam; Szłyk, Edward

    2004-11-01

    A series of Pd(II) and Pt(II) complexes with 6-mercaptopurine (6-Hmp) of formulae Pd(6-Hmp) 2Cl 2 ( 1), Pd(6-mp) 2·2H 2O ( 2), Pt(6-mp) 2·2H 2O ( 3), Pt(6-mp)(dmso)Cl ( 4) was synthesized and studied by IR, far-IR, 1H, 13C, 15N NMR. ( 1) has an ionic character and consists of distinct [Pd(6-Hmp) 2] 2+ cations and uncoordinated Cl - anions, whereas ( 2,3) are neutral species with central atoms bis-chelated by the deprotonated 6-mp - ligands. NMR studies suggest that S and N(7) are the complexation sites, while far-IR spectra indicate the square-planar geometry of Pd(II) or Pt(II). In ( 4) the Pt(II) atom is coordinated by one chelating 6-mp - anion, S-bonded dmso molecule and a terminal chloride. The antiproliferative activity in vitro of ( 2-4) was tested against human leukaemia HL-60 cells, being exhibited for ( 2) at the level ca. six times lower than in case of cisplatin.

  19. Haploinsufficiency for Core Exon Junction Complex Components Disrupts Embryonic Neurogenesis and Causes p53-Mediated Microcephaly.

    PubMed

    Mao, Hanqian; McMahon, John J; Tsai, Yi-Hsuan; Wang, Zefeng; Silver, Debra L

    2016-09-01

    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

  20. 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

    2016-03-01

    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. PMID:26863089

  1. Interactions between plutonism and detachments during metamorphic core complex formation, Serifos Island (Cyclades, Greece)

    NASA Astrophysics Data System (ADS)

    Rabillard, Aurélien; Arbaret, Laurent; Jolivet, Laurent; Le Breton, Nicole; Gumiaux, Charles; Augier, Romain; Grasemann, Bernhard

    2015-06-01

    In order to better understand the interactions between plutonic activity and strain localization during metamorphic core complex formation, the Miocene granodioritic pluton of Serifos (Cyclades, Greece) is studied. This pluton (11.6-9.5 Ma) intruded the Cycladic Blueschists during thinning of the Aegean domain along a system of low-angle normal faults belonging to the south dipping West Cycladic Detachment System (WCDS). Based on structural fieldwork, together with microstructural observations and anisotropy of magnetic susceptibility, we recognize a continuum of deformation from magmatic to brittle conditions within the magmatic body. This succession of deformation events is kinematically compatible with the development of the WCDS. The architecture of the pluton shows a marked asymmetry resulting from its interaction with the detachments. We propose a tectonic scenario for the emplacement of Serifos pluton and its subsequent cooling during the Aegean extension: (1) A first stage corresponds to the metamorphic core complex initiation and associated southwestward shearing along the Meghàlo Livadhi detachment. (2) In the second stage, the Serifos pluton has intruded the dome at shallow crustal level, piercing through the ductile/brittle Meghàlo Livadhi detachment. Southwest directed extensional deformation was contemporaneously transferred upward in the crust along the more localized Kàvos Kiklopas detachment. (3) The third stage was marked by synmagmatic extensional deformation and strain localization at the contact between the pluton and the host rocks resulting in nucleation of narrow shear zones, which (4) continued to develop after the pluton solidification.

  2. 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.

  3. 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.

  4. Structural Preferences in Phosphanylthiolato Platinum(II) Complexes

    PubMed Central

    Duran, Josep; Real, Julio; Benet‐Buchholz, Jordi; Solà, Miquel

    2015-01-01

    Abstract The transition‐metal complexes of heterotopic phosphanylthiolato ligands are useful in various reactions which depend on the stereochemistry of the complexes. Bis‐chelate complex [Pt(SCH2CH2PPh2‐κ2 P,S)2] (1) was obtained in good yields by direct base‐free substitution reaction of the corresponding phosphanylthiol (HSCH2CH2PPh2) with K2PtCl4 or by oxidative addition of the same phosphanylthiol to Pt(PPh3)4. In agreement with the antisymbiosis rule, complex 1 shows a cis‐P,P arrangement in solid state crystallizing in the monoclinic system (C2/c). Density functional theory (DFT) calculations on 1 reveal the right characteristics for the preferred cis‐P,P arrangement, rationalizing its formation. Direct base‐free reaction of [PtCl2(1,5‐cyclooctadiene)] with one equivalent of the same phosphanylthiol produce the trinuclear complex [PtCl(μ‐SCH2CH2PPh2‐κ2 P,S)]3 (2) instead of the binuclear structure common in palladium and nickel derivatives. Crystals of 2 are triclinic (P 1‾ ) showing a sulfur‐bridging edge‐sharing cyclic trinuclear complex with square‐planar coordination geometry around the platinum atoms and a Pt3S3 cycle in skew‐boat conformation. This preference for the trinuclear structure was rationalized mechanistically and through conceptual DFT. PMID:27308212

  5. 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.

  6. Bis(mu-oxo)dimetal "diamond" cores in copper and iron complexes relevant to biocatalysis.

    PubMed

    Que, Lawrence; Tolman, William B

    2002-04-01

    Although quite a familiar feature in high-valent manganese chemistry, the M(2)(mu-O)(2) diamond core motif has only recently been found in synthetic complexes for M=Cu or Fe. Structural and spectroscopic characterization of these more reactive Cu(2)(mu-O)(2) and Fe(2)(mu-O)(2) compounds has been possible through use of appropriately designed supporting ligands, low-temperature handling methods, and techniques such as electrospray ionization mass spectrometry and X-ray crystallography with area detector instrumentation for rapid data collection. Despite differences in electronic structures that have been revealed through experimental and theoretical studies, Cu(2)(mu-O)(2) and Fe(2)(mu-O)(2) cores exhibit analogously covalent metal-oxo bonding, remarkably congruent Raman and extended X-ray absorption fine structure (EXAFS) signatures, and similar tendencies to abstract hydrogen atoms from substrates. Core isomerization is another common reaction attribute, although different pathways are traversed; for Fe, bridge-to-terminal oxo migration has been discovered, while for Cu, reversible formation of an O-O bond to yield a peroxo isomer has been identified. Our understanding of biocatalysis has been enhanced significantly through the isolation and comprehensive characterization of the Cu(2)(mu-O)(2) and Fe(2)(mu-O)(2) complexes. In particular, it has led to the development of new mechanistic notions about how non-heme multimetal enzymes, such as methane monooxygenases, fatty acid desaturase, and tyrosinase, may function in the activation of dioxygen to catalyze a diverse array of organic transformations. PMID:12491240

  7. 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.

  8. 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. PMID:27552124

  9. Structural Basis for a Unique ATP Synthase Core Complex from Nanoarcheaum equitans.

    PubMed

    Mohanty, Soumya; Jobichen, Chacko; Chichili, Vishnu Priyanka Reddy; Velázquez-Campoy, Adrián; Low, Boon Chuan; Hogue, Christopher W V; Sivaraman, J

    2015-11-01

    ATP synthesis is a critical and universal life process carried out by ATP synthases. Whereas eukaryotic and prokaryotic ATP synthases are well characterized, archaeal ATP synthases are relatively poorly understood. The hyperthermophilic archaeal parasite, Nanoarcheaum equitans, lacks several subunits of the ATP synthase and is suspected to be energetically dependent on its host, Ignicoccus hospitalis. This suggests that this ATP synthase might be a rudimentary machine. Here, we report the crystal structures and biophysical studies of the regulatory subunit, NeqB, the apo-NeqAB, and NeqAB in complex with nucleotides, ADP, and adenylyl-imidodiphosphate (non-hydrolysable analog of ATP). NeqB is ∼20 amino acids shorter at its C terminus than its homologs, but this does not impede its binding with NeqA to form the complex. The heterodimeric NeqAB complex assumes a closed, rigid conformation irrespective of nucleotide binding; this differs from its homologs, which require conformational changes for catalytic activity. Thus, although N. equitans possesses an ATP synthase core A3B3 hexameric complex, it might not function as a bona fide ATP synthase. PMID:26370083

  10. Polynuclear and mixed-ligand complexes of copper(II) and nickel(II) with (1-hydroxyethylidene)bisphosphonic acid

    SciTech Connect

    Amirov, R.R.; Saprykova, Z.A.

    1987-12-20

    The compositions and stabilities of heteronuclear and mixed-ligand copper(II) and nickel(II) (1-hydroxyethylidene)bisphosphonates were determined. Parameters of the compatibility of the ligands and central ions in the complexes were calculated. It was shown that the monoprotonated anion of (1-hydroxyethylidene)bisphosphonic acid is capable of terdentate coordination with the participation of the alcoholic hydroxy group. The acidities of the solutions were determined on a pH-673 meter. The spin-lattice relaxation time was measured on a pulse NMR spectrometer.

  11. 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.

  12. 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

  13. Formation and fate of a complete 31-protein RNA polymerase II transcription preinitiation complex.

    PubMed

    Murakami, Kenji; Calero, Guillermo; Brown, Christopher R; Liu, Xin; Davis, Ralph E; Boeger, Hinrich; Kornberg, Roger D

    2013-03-01

    Whereas individual RNA polymerase II (pol II)-general transcription factor (GTF) complexes are unstable, an assembly of pol II with six GTFs and promoter DNA could be isolated in abundant homogeneous form. The resulting complete pol II transcription preinitiation complex (PIC) contained equimolar amounts of all 31 protein components. An intermediate in assembly, consisting of four GTFs and promoter DNA, could be isolated and supplemented with the remaining components for formation of the PIC. Nuclease digestion and psoralen cross-linking mapped the PIC between positions -70 and -9, centered on the TATA box. Addition of ATP to the PIC resulted in quantitative conversion to an open complex, which retained all 31 proteins, contrary to expectation from previous studies. Addition of the remaining NTPs resulted in run-off transcription, with an efficiency that was promoter-dependent and was as great as 17.5% with the promoters tested. PMID:23303183

  14. Assembly of Tom6 and Tom7 into the TOM core complex of Neurospora crassa.

    PubMed

    Dembowski, M; Kunkele, K P; Nargang, F E; Neupert, W; Rapaport, D

    2001-05-25

    Translocation of preproteins across the mitochondrial outer membrane is mediated by the translocase of the outer mitochondrial membrane (TOM) complex. We report the molecular identification of Tom6 and Tom7, two small subunits of the TOM core complex in the fungus Neurospora crassa. Cross-linking experiments showed that both proteins were found to be in direct contact with the major component of the pore, Tom40. In addition, Tom6 was observed to interact with Tom22 in a manner that depends on the presence of preproteins in transit. Precursors of both proteins are able to insert into the outer membrane in vitro and are assembled into authentic TOM complexes. The insertion pathway of these proteins shares a common binding site with the general import pathway as the assembly of both Tom6 and Tom7 was competed by a matrix-destined precursor protein. This assembly was dependent on the integrity of receptor components of the TOM machinery and is highly specific as in vitro-synthesized yeast Tom6 was not assembled into N. crassa TOM complex. The targeting and assembly information within the Tom6 sequence was found to be located in the transmembrane segment and a flanking segment toward the N-terminal, cytosolic side. A hybrid protein composed of the C-terminal domain of yeast Tom6 and the cytosolic domain of N. crassa Tom6 was targeted to the mitochondria but was not taken up into TOM complexes. Thus, both segments are required for assembly into the TOM complex. A model for the topogenesis of the small Tom subunits is discussed. PMID:11278536

  15. 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.

  16. 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.

  17. Plane Transformations in a Complex Setting II: Isometries

    ERIC Educational Resources Information Center

    Dana-Picard, Thierry

    2007-01-01

    This paper is the second part of a study of plane transformations using a complex setting. The first part was devoted to homotheties and translations, now attention is turned towards plane isometries. The group theoretic properties of plane isometries are easy to derive and images of classical geometrical objects by these transformations are…

  18. 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

  19. Effect of axial coordination on the electronic structure and biological activity of dirhodium(II,II) complexes.

    PubMed

    Aguirre, J Dafhne; Lutterman, Daniel A; Angeles-Boza, Alfredo M; Dunbar, Kim R; Turro, Claudia

    2007-09-01

    The reactivities toward biomolecules of a series of three dirhodium(II,II) complexes that possess an increasing number of accessible axial coordination sites are compared. In cis-[Rh2(OAc)2(np)2]2+ (1; np=1,8-naphthyridine) both axial sites are available for coordination, whereas for cis-[Rh2(OAc)2(np)(pynp)]2+ (2; pynp=2-(2-pyridyl)1,8-naphthyridine) and cis-[Rh2(OAc)2(pynp)2]2+ (3) the bridging pynp ligand blocks one and two of the axial coordination sites in the complexes, respectively. The electronic absorption spectra of the complexes are consistent with strong metal-to-ligand charge transfer transitions at low energy and ligand-centered peaks localized on the np and/or pynp ligands in the UV and near-UV regions. Time-dependent density functional theory calculations were used to aid in the assignments. The three complexes exhibit metal-centered oxidations and reductions, localized on the aromatic ligands. The ability of the complexes to stabilize duplex DNA and to inhibit transcription in vitro is greatly affected by the availability of an open axial coordination site. The present work shows that open axial coordination sites on the dirhodium complexes are necessary for biological activity. PMID:17685607

  20. Non-photochemical Fluorescence Quenching in Photosystem II Antenna Complexes by the Reaction Center Cation Radical.

    PubMed

    Paschenko, V Z; Gorokhov, V V; Grishanova, N P; Korvatovskii, B N; Ivanov, M V; Maksimov, E G; Mamedov, M D

    2016-06-01

    In direct experiments, rate constants of photochemical (kP) and non-photochemical (kP(+)) fluorescence quenching were determined in membrane fragments of photosystem II (PSII), in oxygen-evolving PSII core particles, as well as in core particles deprived of the oxygen-evolving complex. For this purpose, a new approach to the pulse fluorometry method was implemented. In the "dark" reaction center (RC) state, antenna fluorescence decay kinetics were measured under low-intensity excitation (532 nm, pulse repetition rate 1 Hz), and the emission was registered by a streak camera. To create a "closed" [P680(+)QA(-)] RC state, a high-intensity pre-excitation pulse (pump pulse, 532 nm) of the sample was used. The time advance of the pump pulse against the measuring pulse was 8 ns. In this experimental configuration, under the pump pulse, the [P680(+)QA(-)] state was formed in RC, whereupon antenna fluorescence kinetics was measured using a weak testing picosecond pulsed excitation light applied to the sample 8 ns after the pump pulse. The data were fitted by a two-exponential approximation. Efficiency of antenna fluorescence quenching by the photoactive RC pigment in its oxidized (P680(+)) state was found to be ~1.5 times higher than that of the neutral (P680) RC state. To verify the data obtained with a streak camera, control measurements of PSII complex fluorescence decay kinetics by the single-photon counting technique were carried out. The results support the conclusions drawn from the measurements registered with the streak camera. In this case, the fitting of fluorescence kinetics was performed in three-exponential approximation, using the value of τ1 obtained by analyzing data registered by the streak camera. An additional third component obtained by modeling the data of single photon counting describes the P680(+)Pheo(-) charge recombination. Thus, for the first time the ratio of kP(+)/kP = 1.5 was determined in a direct experiment. The mechanisms of higher

  1. 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.

  2. 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

  3. 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

  4. SREBP-1a activation by HBx and the effect on hepatitis B virus enhancer II/core promoter.

    PubMed

    Qiao, Ling; Wu, Qi; Lu, Xinya; Zhou, Yan; Fernández-Alvarez, Ana; Ye, Lihong; Zhang, Xiaodong; Han, Jihong; Casado, Marta; Liu, Qiang

    2013-03-22

    Hepatitis B virus (HBV) X protein (HBx) plays an important role in HBV pathogenesis by regulating gene expression. Sterol regulatory element binding protein-1a (SREBP-1a) is a key transcriptional factor for modulating fatty acid and cholesterol synthesis. Here we demonstrated that HBx increased mature SREBP-1a protein level in the nucleus and its activity as a transcription factor. We further showed that the up-regulation of SREBP-1a by HBx occurred at the transcriptional level after ectopic expression and in the context of HBV replication. Deletional analysis using SREBP-1a promoter revealed that the sequence from -436 to -398 in the promoter was required for its activation by HBx. This promoter region possesses the binding sequences for two basic leucine zipper (b-ZIP) transcription factors, namely C/EBP and E4BP4. Mutagenesis of the binding sequences on the SREBP-1a promoter and ectopic expression experiments demonstrated that C/EBPα enhanced SREBP-1a activation by HBx, while E4BP4 had an inhibitory effect. C/EBPα was able to significantly reverse the inhibitory activity of E4BP4 on SREBP-1a promoter. These results demonstrated that HBx activates SREBP-1a activity at the transcription level through a complex mechanism involving two bZIP transcription factors C/EBP and E4BP4 with C/EBP being the dominant positive factor. Finally, we showed that knocking down SREBP-1 abolishes HBV enhancer II/core promoter activation by HBx. PMID:23422505

  5. Synthesis, spectral characterization and biological evaluation of copper(II) and nickel(II) complexes with thiosemicarbazones derived from a bidentate Schiff base

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Bargujar, Savita; Nirwal, Rita; Yadav, Neesha

    2013-04-01

    Complexes of copper(II) and nickel(II) of general composition M(L)2X2, have been synthesized with the ligand 1-Tetralone thiosemicarbazone (where L = 1-Tetralone thiosemicarbazone and X=Cl,1/2SO42-). The molar conductance of the complexes in fresh solution of DMSO lies in the range of 10-20 Ω-1 cm2 mol-1 indicating their non-electrolytic behavior. Thus, the complexes may be formulated as [M(L2)X2]. Ligand was characterized by mass, NMR, IR and single crystallographic studies. All the complexes were characterized by elemental analyses, magnetic moments, IR, electronic and EPR spectral studies. The IR spectral data of ligand indicated the involvement of sulfur and azomethine nitrogen in coordination to the central metal ion. The copper(II) and nickel(II) complexes were found to have magnetic moments1.93-1.96 BM and 2.91-2.94 BM corresponding to one and two unpaired electrons respectively. On the basis of molar conductance, EPR, electronic and infrared spectral studies, a tetragonal geometry has been assigned for Cu(II) chloride complex and trigonal bipyramidal to Cu(II) sulfate complex but an octahedral geometry for Ni(II) complexes. Newly synthesized ligand and its Cu(II) and Ni(II) complexes have also been screened against different bacterial and fungal species.

  6. Synthesis, spectroscopic and catalytic studies of Cu(II), Co(II) and Ni(II) complexes immobilized on Schiff base modified chitosan

    NASA Astrophysics Data System (ADS)

    Antony, R.; Theodore David Manickam, S.; Saravanan, K.; Karuppasamy, K.; Balakumar, S.

    2013-10-01

    A new class of bidentate (N, O) Schiff base ligand (L) has been derived from the functional biopolymer (chitosan) and 1,2-diphenylethanedione in 1:1 M ratio. This ligand has been used to synthesise the new first row transition metal complexes of Cu(II), Co(II) and Ni(II). The structural properties of the ligand and the synthesized tetra-coordinated complexes have been investigated by elemental analysis, magnetic study, molar conductance measurement and spectroscopic methods viz. FT-IR, UV-Vis., 1H NMR, 13C NMR and XRD. The spectral evidences strongly suggested the square planar geometry to the complexes. The XRD studies proved that crystallinity of chitosan has been diminished after Schiff base formation and metal complexation of L. Thermal and surface properties of the complexes have been also discussed from the investigation of their TG-DTG curves and SEM images, respectively. In addition, the catalytic efficiency of these complexes has been studied in the cyclohexane oxidation reaction using H2O2 as oxidant at 70 °C.

  7. 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.

  8. 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.

  9. DNA/RNA binding and anticancer/antimicrobial activities of polymer-copper(II) complexes

    NASA Astrophysics Data System (ADS)

    Lakshmipraba, Jagadeesan; Arunachalam, Sankaralingam; Riyasdeen, Anvarbatcha; Dhivya, Rajakumar; Vignesh, Sivanandham; Akbarsha, Mohammad Abdulkader; James, Rathinam Arthur

    2013-05-01

    Water soluble polymer-copper(II) complexes with various degrees of coordination in the polymer chain were synthesized and characterized by elemental analysis, IR, UV-visible and EPR spectra. The DNA/RNA binding behavior of these polymer-copper(II) complexes was examined by UV-visible absorption, emission and circular dichroism spectroscopic methods, and cyclic voltammetry techniques. The binding of the polymer-copper(II) complexes with DNA/RNA was mainly through intercalation but some amount of electrostatic interaction was also observed. This binding capacity increased with the degree of coordination of the complexes. The polymer-copper(II) complex having the highest degree of coordination was subjected to analysis of cytotoxic and antimicrobial properties. The cytotoxicity study indicated that the polymer-copper(II) complexes affected the viability of MCF-7 mammary carcinoma cells, and the cells responded to the treatment with mostly through apoptosis although a few cells succumbed to necrosis. The antimicrobial screening showed activity against some human pathogens.

  10. Structural and spectroscopic characterization of two new blue luminescent pyridylbenzimidazole zinc(II) complexes.

    PubMed

    DeStefano, Matthew R; Geiger, David K

    2016-06-01

    Luminescent metal complexes are used in photooptical devices. Zinc(II) complexes are of interest because of the ability to tune their color, their high thermal stability and their favorable carrier transport character. In particular, some zinc(II) complexes with aryl diimine and/or heterocyclic ligands have been shown to emit brightly in the blue region of the spectrum. Zinc(II) complexes bearing derivatized imidazoles have been explored for possible optoelectronic applications. The structures of two zinc(II) complexes of 5,6-dimethyl-2-(pyridin-2-yl)-1-[(pyridin-2-yl)methyl]-1H-benzimidazole (L), namely dichlorido(dimethylformamide-κO){5,6-dimethyl-2-(pyridin-2-yl-κN)-1-[(pyridin-2-yl)methyl]-1H-benzimidazole-κN(3)}zinc(II) dimethylformamide monosolvate, [ZnCl2(C20H18N4)(C3H7NO)]·C3H7NO, (I), and bis(acetato-κ(2)O,O'){5,6-dimethyl-2-(pyridin-2-yl-κN)-1-[(pyridin-2-yl)methyl]-1H-benzimidazole-κN(3)}zinc(II) ethanol monosolvate, [Zn(C2H3O2)2(C20H18N4)]·C2H5OH, (II), are reported. Complex (I) crystallized as a dimethylformamide solvate and exhibits a distorted trigonal bipyramidal coordination geometry. The coordination sphere consists of a bidentate L ligand spanning axial to equatorial sites, two chloride ligands in equatorial sites, and an O-bound dimethylformamide ligand in the remaining axial site. The other complex, (II), crystallized as an ethanol solvate. The Zn(II) atom has a distorted trigonal prismatic coordination geometry, with two bidentate acetate ligands occupying two edges and a bidentate L ligand occupying the third edge of the prism. Complexes (I) and (II) emit in the blue region of the spectrum. The results of density functional theory (DFT) calculations suggest that the luminescence of L results from π*←π transitions and that the luminescence of the complexes results from interligand charge-transfer transitions. The orientation of the 2-(pyridin-2-yl) substituent with respect to the benzimidazole system was found to have an impact on

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

    NASA Astrophysics Data System (ADS)

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

    2001-05-01

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

  12. Synthesis and spectroscopic studies on complexes of N,N'-bis-(2-pyridinecarboxaldimine)-1,8-diaminonaphthalene (L); DNA binding studies on Cu(II) complex

    NASA Astrophysics Data System (ADS)

    Shakir, Mohammad; Azam, Mohammad; Parveen, Shama; Khan, Asad U.; Firdaus, Farha

    2009-01-01

    The Schiff base ligand, N,N'-bis-(2-pyridinecarboxaldimine)-1,8-diaminonaphthalene (L), obtained by the condensation of 2-pyridinecarboxaldehyde and 1,8-diaminonaphthalene, has been used to synthesize the mononuclear complexes of the type [MLCl 2] [M = Co(II), Ni(II), Cu(II) and Zn(II)]. The newly synthesized ligand (L) and its complexes have been characterized on the basis of results of elemental analysis, molar conductance, magnetic susceptibility measurements, Job's method and spectroscopic studies viz., FT-IR, Mass, 1H and 13C NMR. The UV-vis and magnetic moment data revealed an octahedral geometry around Co(II), Ni(II) and Cu(II) ions and conductivity data show a non-electrolytic nature of the complexes. Absorption and fluorescence spectroscopic studies support that Cu(II) complex exhibits significant binding to calf thymus DNA.

  13. Synthesis, investigation and spectroscopic characterization of piroxicam ternary complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with glycine and DL-phenylalanine

    NASA Astrophysics Data System (ADS)

    Mohamed, Gehad G.; El-Gamel, Nadia E. A.

    2004-11-01

    The ternary piroxicam (Pir; 4-hydroxy-2-methyl- N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide) complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with various amino acids (AA) such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized by elemental analyses, molar conductance, IR, UV-Vis, magnetic moment, diffuse reflectance and X-ray powder diffraction. The UV-Vis spectra of Pir and the effect of metal chelation on the different interligand transitions are discussed in detailed manner. IR and UV-Vis spectra confirm that Pir behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine- N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its carboxylic group, in addition PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its carboxylic and amino groups. All the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. The molar conductance data reveal that most of these chelates are non electrolytes, while Fe(III)-Pir-Gly, Co(II)-, Ni(II)-, Cu(II)- and Zn(II)-Pir-PhA cheletes were 1:1 electrolytes. X-ray powder diffraction is used as a new tool to estimate the crystallinity of chelates as well as to elucidate their geometrical structures.

  14. Isolation of Plant Photosystem II Complexes by Fractional Solubilization.

    PubMed

    Haniewicz, Patrycja; Floris, Davide; Farci, Domenica; Kirkpatrick, Joanna; Loi, Maria C; Büchel, Claudia; Bochtler, Matthias; Piano, Dario

    2015-01-01

    Photosystem II (PSII) occurs in different forms and supercomplexes in thylakoid membranes. Using a transplastomic strain of Nicotiana tabacum histidine tagged on the subunit PsbE, we have previously shown that a mild extraction protocol with β-dodecylmaltoside enriches PSII characteristic of lamellae and grana margins. Here, we characterize residual granal PSII that is not extracted by this first solubilization step. Using affinity purification, we demonstrate that this PSII fraction consists of PSII-LHCII mega- and supercomplexes, PSII dimers, and PSII monomers, which were separated by gel filtration and functionally characterized. Our findings represent an alternative demonstration of different PSII populations in thylakoid membranes, and they make it possible to prepare PSII-LHCII supercomplexes in high yield. PMID:26697050

  15. Isolation of Plant Photosystem II Complexes by Fractional Solubilization

    PubMed Central

    Haniewicz, Patrycja; Floris, Davide; Farci, Domenica; Kirkpatrick, Joanna; Loi, Maria C.; Büchel, Claudia; Bochtler, Matthias; Piano, Dario

    2015-01-01

    Photosystem II (PSII) occurs in different forms and supercomplexes in thylakoid membranes. Using a transplastomic strain of Nicotiana tabacum histidine tagged on the subunit PsbE, we have previously shown that a mild extraction protocol with β-dodecylmaltoside enriches PSII characteristic of lamellae and grana margins. Here, we characterize residual granal PSII that is not extracted by this first solubilization step. Using affinity purification, we demonstrate that this PSII fraction consists of PSII-LHCII mega- and supercomplexes, PSII dimers, and PSII monomers, which were separated by gel filtration and functionally characterized. Our findings represent an alternative demonstration of different PSII populations in thylakoid membranes, and they make it possible to prepare PSII-LHCII supercomplexes in high yield. PMID:26697050

  16. Nanomolar pyrophosphate detection and nucleus staining in living cells with simple terpyridine-Zn(II) complexes.

    PubMed

    Chao, Duobin; Ni, Shitan

    2016-01-01

    Great efforts have been made to develop fluorescent probes for pyrophosphate (PPi) detection. Nucleus staining with fluorescence microscopy has been also widely investigated. But fluorescent probes for PPi detection with high sensitivity in water medium and nucleus staining with low-cost non-precious metal complexes in living cells are still challenging. Herein, we report simple terpyridine-Zn(II) complexes for selective nanomolar PPi detection over ATP and ADP in water based on aggregation induced emission (AIE) and intramolecular charge transfer (ICT). In addition, these terpyridine-Zn(II) complexes were successfully employed for nucleus staining in living cells. These results demonstrated simply obtained terpyridine-Zn(II) complexes are powerful tool for PPi detection and the development of PPi-related studies. PMID:27198968

  17. Nanomolar pyrophosphate detection and nucleus staining in living cells with simple terpyridine–Zn(II) complexes

    NASA Astrophysics Data System (ADS)

    Chao, Duobin; Ni, Shitan

    2016-05-01

    Great efforts have been made to develop fluorescent probes for pyrophosphate (PPi) detection. Nucleus staining with fluorescence microscopy has been also widely investigated. But fluorescent probes for PPi detection with high sensitivity in water medium and nucleus staining with low–cost non–precious metal complexes in living cells are still challenging. Herein, we report simple terpyridine–Zn(II) complexes for selective nanomolar PPi detection over ATP and ADP in water based on aggregation induced emission (AIE) and intramolecular charge transfer (ICT). In addition, these terpyridine–Zn(II) complexes were successfully employed for nucleus staining in living cells. These results demonstrated simply obtained terpyridine–Zn(II) complexes are powerful tool for PPi detection and the development of PPi–related studies.

  18. Reductive nitrosylation of nickel(ii) complex by nitric oxide followed by nitrous oxide release.

    PubMed

    Ghosh, Somnath; Deka, Hemanta; Dangat, Yuvraj B; Saha, Soumen; Gogoi, Kuldeep; Vanka, Kumar; Mondal, Biplab

    2016-06-21

    Ni(ii) complex of ligand ( = bis(2-ethyl-4-methylimidazol-5-yl)methane) in methanol solution reacts with an equivalent amount of NO resulting in a corresponding Ni(i) complex. Adding further NO equivalent affords a Ni(i)-nitrosyl intermediate with the {NiNO}(10) configuration. This nitrosyl intermediate upon subsequent reaction with additional NO results in the release of N2O and formation of a Ni(ii)-nitrito complex. Crystallographic characterization of the nitrito complex revealed a symmetric η(2)-O,O-nitrito bonding to the metal ion. This study demonstrates the reductive nitrosylation of a Ni(ii) center followed by N2O release in the presence of excess NO. PMID:27230278

  19. Nanomolar pyrophosphate detection and nucleus staining in living cells with simple terpyridine–Zn(II) complexes

    PubMed Central

    Chao, Duobin; Ni, Shitan

    2016-01-01

    Great efforts have been made to develop fluorescent probes for pyrophosphate (PPi) detection. Nucleus staining with fluorescence microscopy has been also widely investigated. But fluorescent probes for PPi detection with high sensitivity in water medium and nucleus staining with low–cost non–precious metal complexes in living cells are still challenging. Herein, we report simple terpyridine–Zn(II) complexes for selective nanomolar PPi detection over ATP and ADP in water based on aggregation induced emission (AIE) and intramolecular charge transfer (ICT). In addition, these terpyridine–Zn(II) complexes were successfully employed for nucleus staining in living cells. These results demonstrated simply obtained terpyridine–Zn(II) complexes are powerful tool for PPi detection and the development of PPi–related studies. PMID:27198968

  20. Complex inner core of the Earth: The last frontier of global seismology

    NASA Astrophysics Data System (ADS)

    Tkalčić, Hrvoje

    2015-03-01

    The days when the Earth's inner core (IC) was viewed as a homogeneous solid sphere surrounded by the liquid outer core (OC) are now behind us. Due to a limited number of data sampling the IC and a lack of experimentally controlled conditions in the deep Earth studies, it has been difficult to scrutinize competitive hypotheses in this active area of research. However, a number of new concepts linking IC structure and dynamics has been proposed lately to explain different types of seismological observations. A common denominator of recent observational work on the IC is increased complexity seen in IC physical properties such as its isotropic and anisotropic structure, attenuation, inner core boundary (ICB) topography, and its rotational dynamics. For example, small-scale features have been observed to exist as a widespread phenomenon in the uppermost inner core, probably superimposed on much longer-scale features. The characterization of small-scale features sheds light on the nature of the solidification process and helps in understanding seismologically observed hemispherical dichotomy of the IC. The existence of variations in the rate and level of solidification is a plausible physical outcome in an environment where vigorous compositional convection in the OC and variations in heat exchange across the ICB may control the process of crystal growth. However, further progress is hindered by the fact that the current traveltime data of PKIKP waves traversing the IC do not allow discriminating between variations in isotropic P wave velocity and velocity anisotropy. Future studies of attenuation in the IC might provide crucial information about IC structure, although another trade-off exists—that of the relative contribution of scattering versus viscoelastic attenuation and the connection with the material properties. Future installations of dense arrays, cross paths of waves that sample the IC, and corresponding array studies will be a powerful tool to image and

  1. Tetra- and hexadentate Schiff base ligands and their Ni(II), Cu(II) and Zn(II) complexes. Synthesis, spectral, magnetic and thermal studies.

    PubMed

    Ismail, Tarek M A; Saleh, Akila A; El Ghamry, Mosad A

    2012-02-01

    Tetradentate N(2)O(2), N(4) Schiff bases, 1,2-bis(4-oxopent-2-ylideneamino) benzene (BOAB), 1-(4-oxopent-2-ylideneamino-2-[(2-hydroxyphenyl)ethylideneamino] benzene (OAHAB), 7,16-bis(4-chlorobenzylidene)-6,8,15,17-tetra-methyl-7,16-dihydro -5,9,14,18-tetraza-dibenzo[a,h] cyclo tetradecene (BCBDCT), 7,16-bis(2-hydroxy-benzylidene)-6,8,15,17-tetramethyl-7,16-dihydro-5,9,14,18-tetraza-dibenzo [a,h] cyclo tetradecene (BHBDCT) and hexadentate N(4)O(2) Schiff bases, 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(2-hydroxybenzylidene) pentane (BHAPHP), 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(4-chlorobenzylidene) pentane (BHAPCP) were prepared and characterized by elemental analysis, IR, UV-Vis, (1)H NMR and mass spectra. The solid complexes of the prepared Schiff base ligands with Ni(II), Cu(II) and Zn(II) ions were isolated and characterized by elemental and thermal analyses, IR, electronic and ESR spectra as well as conductance and magnetic susceptibility measurements. The results showed that most complexes have octahedral geometry but few can attain the tetrahedral arrangement. The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for decomposition steps in Cu(II) complexes thermograms have been calculated. PMID:22070996

  2. Tetra- and hexadentate Schiff base ligands and their Ni(II), Cu(II) and Zn(II) complexes. Synthesis, spectral, magnetic and thermal studies

    NASA Astrophysics Data System (ADS)

    Ismail, Tarek M. A.; Saleh, Akila A.; Ghamry, Mosad A. El

    2012-02-01

    Tetradentate N 2O 2, N 4 Schiff bases, 1,2-bis(4-oxopent-2-ylideneamino) benzene (BOAB), 1-(4-oxopent-2-ylideneamino-2-[(2-hydroxyphenyl)ethylideneamino] benzene (OAHAB), 7,16-bis(4-chlorobenzylidene)-6,8,15,17-tetra-methyl-7,16-dihydro -5,9,14,18-tetraza-dibenzo[a,h] cyclo tetradecene (BCBDCT), 7,16-bis(2-hydroxy-benzylidene)-6,8,15,17-tetramethyl-7,16-dihydro-5,9,14,18-tetraza-dibenzo [a,h] cyclo tetradecene (BHBDCT) and hexadentate N 4O 2 Schiff bases, 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(2-hydroxybenzylidene) pentane (BHAPHP), 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(4-chlorobenzylidene) pentane (BHAPCP) were prepared and characterized by elemental analysis, IR, UV-Vis, 1H NMR and mass spectra. The solid complexes of the prepared Schiff base ligands with Ni(II), Cu(II) and Zn(II) ions were isolated and characterized by elemental and thermal analyses, IR, electronic and ESR spectra as well as conductance and magnetic susceptibility measurements. The results showed that most complexes have octahedral geometry but few can attain the tetrahedral arrangement. The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for decomposition steps in Cu(II) complexes thermograms have been calculated.

  3. Antileishmanial activity of ruthenium(II)tetraammine nitrosyl complexes.

    PubMed

    Pereira, José Clayston Melo; Carregaro, Vanessa; Costa, Diego Luís; da Silva, João Santana; Cunha, Fernando Q; Franco, Douglas Wagner

    2010-09-01

    The complexes trans-[Ru(NO)(NH(3))(4)L](X)(3) (X = BF(4)(-), PF(6)(-) or Cl(-) and L = N-heterocyclic ligands, P(OEt)(3), SO(3)(-2)), and [Ru(NO)Hedta)] were shown to exhibit IC(50pro) in the range of 36 (L = imN) to 5000 microM (L = imC). The inhibitory effects of trans-[Ru(NO)(NH(3))(4)imN](BF(4))(3) and of the Angeli's salt on the growth of the intramacrophage amastigote form studied were found to be similar while the trans-[Ru(NH(3))(4)imN(H(2)O)](2+) complex was found not to exhibit any substantial antiamastigote effect. The trans-[Ru(NO)(NH(3))(4)imN](BF(4))(3) compound, administered (500 nmol kg(-1) day(-1)) in BALB/c mice infected with Leishmania major, was found to exhibit a 98% inhibition on the parasite growth. Furthermore, this complex proved to be at least 66 times more efficient than glucantime in in vivo experiments. PMID:20598778

  4. Upping the Ante of Text Complexity in the Common Core State Standards: Examining Its Potential Impact on Young Readers

    ERIC Educational Resources Information Center

    Hiebert, Elfrieda H.; Mesmer, Heidi Anne E.

    2013-01-01

    The Common Core Standards for the English Language Arts (CCSS) provide explicit guidelines matching grade-level bands (e.g., 2-3, 4-5) with targeted text complexity levels. The CCSS staircase accelerates text expectations for students across Grades 2-12 in order to close a gap in the complexity of texts typically used in high school and those of…

  5. Ligand field spectroscopy of Cu(II) and Ag(II) complexes in the gas phase: theory and experiment.

    PubMed

    Puskar, Ljiljana; Cox, Hazel; Goren, Alan; Aitken, Georgina D C; Stace, Anthony J

    2003-01-01

    Ligand field spectra have been recorded in the gas phase for the two series of complexes containing either Cu(II) or Ag(II) in association with pyridine. Where comparisons are possible, the gas phase spectra match those recorded in the condensed phase; however, for Ag(II) systems the results differ in interpretation. The Ag(II) data are attributed to a ligand-to-metal charge transfer process, and the Cu(II) data (spectral region and extinction coefficient) match the characteristics of a d-d transition. A detailed theoretical analysis of two complexes. [Cu(py)4]2+ and [Ag(py)4]2+ provides evidence of a minimum energy, D4h structure and two less stable D2h and D2d structures within approximately 60 kJ mol(-1). From these structures it is possible to identify a range of optically and vibronically allowed transitions that could contribute to spectra observed in the gas phase. In the case of calculations on [Ag(py)4]2+ there is strong evidence of an electronic transition that would account for the observation of charge transfer in the experiments. Less detailed calculations on [Cu(py)6]2+ and [Ag(py)6]2+ show structural evidence of extensive Jahn Teller distortion. Taken together with incremental binding energies calculated for complexes containing between two and six pyridine molecules, these results show that the level of theory adopted is capable of providing a semi-quantitative understanding of the experimental data. PMID:14527220

  6. 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

  7. 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

  8. Development of Core Complex Domes Due to Along-Axis Variation in Diking

    NASA Astrophysics Data System (ADS)

    Buck, W. R.; Choi, E.; Tian, X.

    2014-12-01

    Continental and oceanic core complexes are characterized by fairly smooth, unfaulted, but corrugated surfaces of high grade rocks often domed both along and orthogonal to the transport direction. The corrugations, or mega-mullions, are remarkably continuous in the transport direction and may be tens of kilometers long. Spencer [1999] suggests that corrugations with across-transport wavelengths of millimeter to ~25 km scales are formed when the lower plate of a large-offset normal fault is "continuously cast," as warm, ductile mantle and gabbro is pulled up against the cooler upper plate. Continuous casting is widely accepted as a mechanism to form the shorter wavelength corrugations as a result of irregularities of the brittle upper plate surface. However, doming is generally ascribed to upflow of buoyant diapirs or transtensional deformation of the lithosphere. We suggest that doming of core complexes can be a product of continuous casting when a large-offset fault evolves to be curved in plan-view. For oceanic core complexes along-axis variation in magmatism can lead to lateral offset of a detachment fault relative to the spreading axis. We assume that near-ridge normal faults form relatively straight and consider that horizontal offsets in the along-axis position of a large-offset fault (or detachment) result from variations in the rate of magmatic diking. Assuming a sinusoidal variation in the rate of dike opening with distance along the axis the evolution of fault offset and the plan-view shape of the active fault is easy to describe. Because the fault length increases as it is offset, the work to slip on the fault increases with time. Eventually, it should be easier to slip in a new straight fault and the conditions for this can be described with an approximate analytic model. We are developing 3D numerical models to test the predictions of this analytic model and show how the topographic amplitude of the domes depends the fault dip, the amplitude of the

  9. 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

  10. Infrared spectroscopic study of copper(II) complexes with N-substituted tetrazoles1

    NASA Astrophysics Data System (ADS)

    Degtyarik, M. M.; Gaponik, P. N.; Naumenko, V. N.; Lesnikovich, A. I.; Nikanovich, M. V.

    The i.r. spectra (4000-200 cm -1) of N-alkyltetrazoles and their complexes with copper(II) salts CuCl 2 and Cu(NCS) 2 have been measured. Spectral criteria in the middle and far regions for the identification of tetrazole isomers and their complexes are proposed. The site of the coordination in a tetrazole molecule and supposed structure of complexes are being discussed.

  11. Spectroscopic study of copper(II) complexes with carboxymethyl dextran and dextran sulfate

    NASA Astrophysics Data System (ADS)

    Glišić, S.; Nikolić, G.; Cakić, M.; Trutić, N.

    2015-07-01

    The copper(II) ion complexes with carboxymethyl dextran (CMD) and dextran sulfate (DS) were studied by different methods. Content of copper was determined by atomic absorption spectroscopy. It was found that copper : ligand mole ratio (Cu : CMD) is 1 : 2, and Cu : DS is 1 : 1 by mole ratio method. Spectrophotometric parameters of synthesized compounds are characteristic for Cu(II) ion in octahedral ( O h ) coordination. Analyzing of FTIR spectra in ν(C=O) vibration region has showed that -COOH group acts as bidentate ligand, while the compounds of Cu(II) with DS copper ions are in the region of four oxygen atoms of two adjacent sulfo groups. The presence of crystalline water was determined by isotopic substitution of H2O molecules with D2O molecules. Comparison of spectra recorded at room (RT) and liquid nitrogen temperature (LNT) has enabled detection bands of water molecules libration indicating that they are coordinated complementing coordination sphere of Cu(II) ions to six. The complexes are of Cu(II) · (CMD)2 · (H2O)2 or Cu(II) · DS · (H2O)2 type. The similarities of the γ(C-H) range in a part of FTIR spectra indicate that there is no difference in the conformation of the 4 C 1 glucopyranose (Glc) unit CMD and DS synthesized Cu(II) complexes.

  12. Young Starless Cores Embedded in the Magnetically Dominated Pipe Nebula. II. Extended Data Set

    NASA Astrophysics Data System (ADS)

    Frau, P.; Girart, J. M.; Beltrán, M. T.; Padovani, M.; Busquet, G.; Morata, O.; Masqué, J. M.; Alves, F. O.; Sánchez-Monge, Á.; Franco, G. A. P.; Estalella, R.

    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 V to N_H_2 factor of (1.27 ± 0.12) × 10-21 mag cm2 and a background visual extinction of ~6.7 mag possibly arising from the cloud material. We derived an average core diameter of ~0.08 pc, density of ~105 cm-3, and mass of ~1.7 M ⊙. 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, C2H, and CS), "oxo-sulfurated" (e.g., SO and CH3OH), and "deuterated" (e.g., N2H+, CN, and HCN) starless core groups. The chemically defined

  13. 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

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

    PubMed Central

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

    2016-01-01

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

  15. Cytotoxic Effects of Newly Synthesized Palladium(II) Complexes of Diethyldithiocarbamate on Gastrointestinal Cancer Cell Lines

    PubMed Central

    Hadizadeh, Shahram; Najafzadeh, Nowruz; Mazani, Mohammad; Mansouri-Torshizi, Hassan; Niapour, Ali

    2014-01-01

    As a part of a drug development program to discover novel therapeutic and more effective palladium (Pd) based anticancer drugs, a series of water-soluble Pd complexes have been synthesized by interaction between [Pd (phen)(H2O)2(NO3)2] and alkylenebisdithiocarbamate(al-bis-dtc) disodium salts. This study was undertaken to examine the possible cytotoxic effect of three novel complexes (0.125–64 µg/mL) on human gastric carcinoma (AGS), esophageal squamous cell carcinoma (Kyse-30), and hepatocellular carcinoma (HepG2) cell lines. The cytotoxicity was examined using cell proliferation and acridine orange/ethidium bromide (AO/EB) assay. In order to examine the effects of new Pd(II) complexes on cell cycle status, we performed cell cycle analysis. The complexes were found to have completely lethal effects on the cell lines, and the half maximal inhibitory concentration (IC50) values obtained for the cell lines were much lower in comparison with cisplatin. We demonstrated that the three new Pd(II) complexes are able to induce G2/M phase arrest in AGS and HepG2; in addition, the Pd(II) complexes caused an S phase arrest in Kyse-30 cell line. Our results indicate that newly synthesized Pd(II) complexes may provide a novel class of chemopreventive compounds for anticancer therapy. PMID:25147738

  16. Unfolding communities in large complex networks: Combining defensive and offensive label propagation for core extraction

    NASA Astrophysics Data System (ADS)

    Šubelj, Lovro; Bajec, Marko

    2011-03-01

    Label propagation has proven to be a fast method for detecting communities in large complex networks. Recent developments have also improved the accuracy of the approach; however, a general algorithm is still an open issue. We present an advanced label propagation algorithm that combines two unique strategies of community formation, namely, defensive preservation and offensive expansion of communities. The two strategies are combined in a hierarchical manner to recursively extract the core of the network and to identify whisker communities. The algorithm was evaluated on two classes of benchmark networks with planted partition and on 23 real-world networks ranging from networks with tens of nodes to networks with several tens of millions of edges. It is shown to be comparable to the current state-of-the-art community detection algorithms and superior to all previous label propagation algorithms, with comparable time complexity. In particular, analysis on real-world networks has proven that the algorithm has almost linear complexity, O(m1.19), and scales even better than the basic label propagation algorithm (m is the number of edges in the network).

  17. Design, spectral characterization and biological studies of transition metal(II) complexes with triazole Schiff bases

    NASA Astrophysics Data System (ADS)

    Hanif, Muhammad; Chohan, Zahid H.

    2013-03-01

    A new series of three biologically active triazole derived Schiff base ligands L1-L3 have been synthesized in equimolar reaction of 3-amino-1H-1,2,4-triazole with pyrrol-2-carboxaldehyde, 4-bromo-thiophene-2-carboxaldehyde, and 5-iodo-2-hydroxy benzaldehyde. The prepared Schiff bases were used for further complex formation reaction with different metal elements like Co(II), Ni(II), Cu(II) and Zn(II) as chlorides by using a molar ratio of ligand:metal as 2:1. The structure and bonding nature of all the compounds were identified by their physical, spectral and analytical data. All the metal(II) complexes possessed an octahedral geometry except the Cu(II) complexes which showed a distorted octahedral geometry. All the synthesized compounds, were studied for their in vitro antibacterial, and antifungal activities, against four Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and against six fungal strains (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata) by using agar-well diffusion method. It has been shown that all the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. In vitro Brine Shrimp bioassay was also carried out to investigate the cytotoxic properties of these compounds. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination.

  18. Design, spectral characterization and biological studies of transition metal(II) complexes with triazole Schiff bases.

    PubMed

    Hanif, Muhammad; Chohan, Zahid H

    2013-03-01

    A new series of three biologically active triazole derived Schiff base ligands L(1)-L(3) have been synthesized in equimolar reaction of 3-amino-1H-1,2,4-triazole with pyrrol-2-carboxaldehyde, 4-bromo-thiophene-2-carboxaldehyde, and 5-iodo-2-hydroxy benzaldehyde. The prepared Schiff bases were used for further complex formation reaction with different metal elements like Co(II), Ni(II), Cu(II) and Zn(II) as chlorides by using a molar ratio of ligand:metal as 2:1. The structure and bonding nature of all the compounds were identified by their physical, spectral and analytical data. All the metal(II) complexes possessed an octahedral geometry except the Cu(II) complexes which showed a distorted octahedral geometry. All the synthesized compounds, were studied for their in vitro antibacterial, and antifungal activities, against four Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and against six fungal strains (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata) by using agar-well diffusion method. It has been shown that all the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. In vitro Brine Shrimp bioassay was also carried out to investigate the cytotoxic properties of these compounds. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination. PMID:23277183

  19. Adsorption phenomena of cubane-type tetranuclear Ni(II) complexes with neutral, thioether-functionalized ligands on Au(111)

    NASA Astrophysics Data System (ADS)

    Heß, Volkmar; Matthes, Frank; Bürgler, Daniel E.; Monakhov, Kirill Yu.; Besson, Claire; Kögerler, Paul; Ghisolfi, Alessio; Braunstein, Pierre; Schneider, Claus M.

    2015-11-01

    The controlled and intact deposition of molecules with specific properties onto surfaces is an emergent field impacting a wide range of applications including catalysis, molecular electronics, and quantum information processing. One strategy is to introduce grafting groups functionalized to anchor to a specific surface. While thiols and disulfides have proven to be quite effective in combination with gold surfaces, other S-containing groups have received much less attention. Here, we investigate the surface anchoring and organizing capabilities of novel charge-neutral heterocyclic thioether groups as ligands of polynuclear nickel(II) complexes. We report on the deposition of a cubane-type {Ni4} (= [Ni(μ3-Cl)Cl(HL·S)]4) single-molecule magnet from dichloromethane solution on a Au(111) surface, investigated by scanning tunneling microscopy, X-ray photoelectron spectroscopy, and low-energy electron diffraction, both immediately after deposition and after subsequent post-annealing. The results provide strong evidence for partial decomposition of the coordination complex upon deposition on the Au(111) surface that, however, leaves the magnetic {Ni4Cl4n} (n = 1 or 2) core intact. Only post-annealing above 480 K induces further decomposition and fragmentation of the {Ni4Cl4n} core. The detailed insight into the chemisorption-induced decomposition pathway not only provides guidelines for the deposition of thioether-functionalized Ni(II) complexes on metallic surfaces but also reveals opportunities to use multidentate organic ligands decorated with thioether groups as transporters for highly unstable inorganic structures onto conducting surfaces, where they are stabilized retaining appealing electronic and magnetic properties.

  20. Ru(0) and Ru(II) nitrosyl pincer complexes: structure, reactivity, and catalytic activity.

    PubMed

    Fogler, Eran; Iron, Mark A; Zhang, Jing; Ben-David, Yehoshoa; Diskin-Posner, Yael; Leitus, Gregory; Shimon, Linda J W; Milstein, David

    2013-10-01

    Despite considerable interest in ruthenium carbonyl pincer complexes and their substantial catalytic activity, there has been relatively little study of the isoelectronic ruthenium nitrosyl complexes. Here we describe the synthesis and reactivity of several complexes of this type as well as the catalytic activity of complex 6. Reaction of the PNP ligand (PNP = 2,6-bis((t)Bu2PCH2)pyridine) with RuCl3(NO)(PPh3)2 yielded the Ru(II) complex 3. Chloride displacement by BAr(F-) (BAr(F-) = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) gave the crystallographicaly characterized, linear NO Ru(II) complex 4, which upon treatment with NaBEt3H yielded the Ru(0) complexes 5. The crystallographically characterized Ru(0) square planar complex 5·BF4 bears a linear NO ligand located trans to the pyridilic nitrogen. Further treatment of 5·BF4 with excess LiOH gave the crystallographicaly characterized Ru(0) square planar, linear NO complex 6. Complex 6 catalyzes the dehydrogenative coupling of alcohols to esters, reaching full conversion under air or under argon. Reaction of the PNN ligand (PNN = 2-((t)Bu2PCH2)-6-(Et2NCH2)pyridine) with RuCl3(NO)(H2O)2 in ethanol gave an equilibrium mixture of isomers 7a and 7b. Further treatment of 7a + 7b with 2 equivalent of sodium isopropoxide gave the crystallographicaly characterized, bent-nitrosyl, square pyramidal Ru(II) complex 8. Complex 8 was also synthesized by reaction of PNN with RuCl3(NO)(H2O)2 and Et3N in ethanol. Reaction of the "long arm" PN(2)N ligand (PN(2)N = 2-((t)Bu2PCH2-)-6-(Et2NCH2CH2)pyridine) with RuCl3(NO)(H2O)2 in ethanol gave complex 9, which upon treatment with 2 equiv of sodium isopropoxide gave complex 10. Complex 10 was also synthesized directly by reaction of PN(2)N with RuCl3(NO)(H2O)2 and a base in ethanol. A noteworthy aspect of these nitrosyl complexes is their preference for the Ru(0) oxidization state over Ru(II). This preference is observed with both aromatized and dearomatized pincer ligands, in

  1. Di-, tri-, and tetranuclear nickel(II) complexes with oximato bridges: magnetism and catecholase-like activity of two tetranuclear complexes possessing rhombic topology.

    PubMed

    Das, Lakshmi Kanta; Biswas, Apurba; Kinyon, Jared S; Dalal, Naresh S; Zhou, Haidong; Ghosh, Ashutosh

    2013-10-21

    Oxime-based tridentate Schiff base ligands 3-[2-(diethylamino)ethylimino]butan-2-one oxime (HL(1)) and 3-[3-(dimethylamino)propylimino]butan-2-one oxime (HL(2)) produced the dinuclear complex [Ni2L(1)2](ClO4)2 (1) and trinuclear complex [Ni3(HL(2))3(μ3-O)](ClO4)4·CH3CN (2), respectively, upon reaction with Ni(ClO4)2·6H2O. However, in a slightly alkaline medium, both of the ligands underwent hydrolysis and resulted in tetranuclear complexes [{Ni(deen)(H2O)}2(μ3-OH)2{Ni2(moda)4}](ClO4)2·2CH3CN (3) and [{Ni(dmpn)(CH3CN)2}2(μ3-OH)2{Ni2(moda)4}](ClO4)2·CH3CN (4), where deen = 2-(diethylamino)ethylamine, dmpn = 3-(dimethylamino)-1-propylamine, and modaH = diacetyl monoxime. All four complexes have been structurally characterized. Complex 1 is a centrosymmetric dimer where the square planar nickel(II) atoms are joined solely by the oximato bridges. In complex 2, three square planar nickel atoms form a triangular core through a central oxido (μ3-O) and peripheral oximato bridges. Tetranuclear complexes 3 and 4 consist of four distorted octahedral nickel(II) ions held together in a rhombic chair arrangement by two central μ3-OH and four peripheral oximato bridges. Magnetic susceptibility measurements indicated that dinuclear 1 and trinuclear 2 exhibited diamagnetic behavior, while tetranuclear complexes 3 and 4 were found to have dominant antiferromagnetic intramolecular coupling with concomitant ferromagnetic interactions. Despite its singlet ground state, both 3 and 4 serve as useful examples of Kahn's model for competing spin interactions. High-frequency EPR studies were also attempted, but no signal was detected, likely due to the large energy gap between the ground and first excited state. Complexes 3 and 4 exhibited excellent catecholase-like activity in the aerial oxidation of 3,5-di-tert-butylcatechol to the corresponding o-quinone, whereas 1 and 2 did not show such catalytic activity. Kinetic data analyses of this oxidation reaction in acetonitrile

  2. Platinum(II) and Palladium(II)