Synthesis, structural and fungicidal studies of hydrazone based coordination compounds

NASA Astrophysics Data System (ADS)

Sharma, Amit Kumar; Chandra, Sulekh

2013-02-01

The coordination compounds of the Co(II), Ni(II) and Cu(II) metal ions derived from imine based ligand, benzil bis(carbohydarzone) were structurally and pharmaceutically studied. The compounds have the general stoichiometry [M(L)]X2 and [Co(L)X2], where M = Ni(II) and Cu(II), and X=NO3- and Cl- ions. The analytical techniques like elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, UV/Visible, NMR, ESI mass and EPR were used to study the compounds. The key IR bands, i.e., amide I, amide II and amide III stretching vibrations accounts for the tetradentate metal binding nature of the ligand. The electronic and EPR spectral results suggest the square planar Ni(II) and Cu(II) complexes (giso = 2.11-2.22) and tetragonal geometry Co(II) complexes (giso = 2.10-2.17). To explore the compounds in the biological field, they were examined against the opportunistic pathogens, i.e., Alternaria brassicae, Aspergillus niger and Fusarium oxysporum. The partial covalent character of metal-ligand bond is supported by the orbital reduction factor k (0.62-0.92) and nephalauxetic parameter β (0.55-0.57).

First JECSS Workshop

NASA Astrophysics Data System (ADS)

Ichiye, Takashi

The first Japan and East China Seas Study (JECSS) workshop convened at Tsukuba University, about 60 km north of Tokyo, Japan, June 1-4, 1981, to assess hydrographic data, review descriptive and theoretical Work, and promote future cooperation for studying the Japan Sea and East China Sea and marginal seas of the Western North Pacific Ocean. The conveners were Takashi Ichiye of Texas A&M University and Kenzo Takano of Tsukuba University, and the workshop was funded by the Hidaka Foundation, which was founded by Koji Hidaka, patriarch of dynamic oceanography in Japan.There were 41 participants: seven from the United States, six from Korea, one from the Peoples Republic of China, and 27 from Japan. Twenty-four papers were presented, and topics included the Japan Sea, the East China Sea, and marginal seas in general. Subjects concerned descriptive physical oceanography; internal waves, tides, and shelf waves; circulation modeling; data assessment; remote sensing; and sedimentology and marine chemistry. The seasonal change of the Tsushima Current, a branch of the Kuroshio in the Japan Sea, was determined by the Tohoku University group; preliminary results of the NOAA R/V Oceanographer cruise in Spring 1980 were presented; and the numerical modeling of the Japan Sea circulation, the tides of the Yellow Sea, and the barotropic current of the East China Sea were discussed. The papers presented will be published in 1982 in La Mer, a journal of the Japanese-French Oceanographical Society.

Synthesis of the (N2)3- radical from Y2+ and its protonolysis reactivity to form (N2H2)2- via the Y[N(SiMe3)2]3/KC8 reduction system.

PubMed

Fang, Ming; Lee, David S; Ziller, Joseph W; Doedens, Robert J; Bates, Jefferson E; Furche, Filipp; Evans, William J

2011-03-23

Examination of the Y[N(SiMe(3))(2)](3)/KC(8) reduction system that allowed isolation of the (N(2))(3-) radical has led to the first evidence of Y(2+) in solution. The deep-blue solutions obtained from Y[N(SiMe(3))(2)](3) and KC(8) in THF at -35 °C under argon have EPR spectra containing a doublet at g(iso) = 1.976 with a 110 G hyperfine coupling constant. The solutions react with N(2) to generate (N(2))(2-) and (N(2))(3-) complexes {[(Me(3)Si)(2)N](2)(THF)Y}(2)(μ-η(2):η(2)-N(2)) (1) and {[(Me(3)Si)(2)N](2)(THF)Y}(2)(μ-η(2):η(2)-N(2))[K(THF)(6)] (2), respectively, and demonstrate that the Y[N(SiMe(3))(2)](3)/KC(8) reaction can proceed through an Y(2+) intermediate. The reactivity of (N(2))(3-) radical with proton sources was probed for the first time for comparison with the (N(2))(2-) and (N(2))(4-) chemistry. Complex 2 reacts with [Et(3)NH][BPh(4)] to form {[(Me(3)Si)(2)N](2)(THF)Y}(2)(μ-N(2)H(2)), the first lanthanide (N(2)H(2))(2-) complex derived from dinitrogen, as well as 1 as a byproduct, consistent with radical disproportionation reactivity.

Redox non-innocence of thioether crowns: elucidation of the electronic structure of the mononuclear Pd(III) complexes [Pd([9]aneS3)2]3+ and [Pd([18]aneS6)]3+.

PubMed

Stephen, Emma; Blake, Alexander J; Carter, Emma; Collison, David; Davies, E Stephen; Edge, Ruth; Lewis, William; Murphy, Damien M; Wilson, Claire; Gould, Robert O; Holder, Alan J; McMaster, Jonathan; Schröder, Martin

2012-02-06

The Pd(II) complexes [Pd([9]aneS(3))(2)](PF(6))(2)·2MeCN (1) ([9]aneS(3) = 1,4,7-trithiacyclononane) and [Pd([18]aneS(6))](PF(6))(2) (2) ([18]aneS(6) = 1,4,7,10,13,16-hexathiacyclooctadecane) can be oxidized electrochemically or chemically oxidized with 70% HClO(4) to [Pd([9]aneS(3))(2)](3+) and [Pd([18]aneS(6))](3+), respectively. These centers have been characterized by single crystal X-ray diffraction, and by UV/vis and multifrequency electron paramagnetic resonance (EPR) spectroscopies. The single crystal X-ray structures of [Pd(III)([9]aneS(3))(2)](ClO(4))(6)·(H(3)O)(3)·(H(2)O)(4) (3) at 150 K and [Pd([18]aneS(6))](ClO(4))(6)·(H(5)O(2))(3) (4) at 90 K reveal distorted octahedral geometries with Pd-S distances of 2.3695(8), 2.3692(8), 2.5356(9) and 2.3490(6), 2.3454(5), 2.5474(6) Å, respectively, consistent with Jahn-Teller distortion at a low-spin d(7) Pd(III) center. The Pd(II) compound [Pd([9]aneS(3))(2)](PF(6))(2) shows a one-electron oxidation process in MeCN (0.2 M NBu(4)PF(6), 293 K) at E(1/2) = +0.57 V vs. Fc(+)/Fc assigned to a formal Pd(III)/Pd(II) couple. Multifrequency (Q-, X-, S-, and L-band) EPR spectroscopic analysis of [Pd([9]aneS(3))(2)](3+) and [Pd([18]aneS(6))](3+) gives g(iso) = 2.024, |A(iso(Pd))| = 18.9 × 10(-4) cm(-1); g(xx) = 2.046, g(yy) = 2.041, g(zz) = 2.004; |A(xx(Pd))| = 24 × 10(-4) cm(-1), |A(yy(Pd))| = 22 × 10(-4) cm(-1), |A(zz(Pd))| = 14 × 10(-4) cm(-1), |a(xx(H))| = 4 × 10(-4) cm(-1), |a(yy(H))| = 5 × 10(-4) cm(-1), |a(zz(H))| = 5.5 × 10(-4) cm(-1) for [Pd([9]aneS(3))(2)](3+), and g(iso) = 2.015, |A(iso(Pd))| = 18.8× 10(-4) cm(-1); g(xx) = 2.048 g(yy) = 2.036, g(zz) = 1.998; |a(xx(H))| = 5, |a(yy(H))| = 5, |a(zz(H))| = 6 × 10(-4) cm(-1); |A(xx(Pd))| = 23× 10(-4) cm(-1), |A(yy(Pd))| = 22 × 10(-4) cm(-1), |A(zz(Pd))| = 4 × 10(-4) cm(-1) for [Pd([18]aneS(6))](3+). Both [Pd([9]aneS(3))(2)](3+) and [Pd([18]aneS(6))](3+) exhibit five-line superhyperfine splitting in the g(zz) region in their frozen solution EPR

Hydroacoustic monitoring of a salt cavity: an analysis of precursory events of the collapse

NASA Astrophysics Data System (ADS)

Lebert, F.; Bernardie, S.; Mainsant, G.

2011-09-01

One of the main features of "post mining" research relates to available methods for monitoring mine-degradation processes that could directly threaten surface infrastructures. In this respect, GISOS, a French scientific interest group, is investigating techniques for monitoring the eventual collapse of underground cavities. One of the methods under investigation was monitoring the stability of a salt cavity through recording microseismic-precursor signals that may indicate the onset of rock failure. The data were recorded in a salt mine in Lorraine (France) when monitoring the controlled collapse of 2 000 000 m3 of rocks surrounding a cavity at 130 m depth. The monitoring in the 30 Hz to 3 kHz frequency range highlights the occurrence of events with high energy during periods of macroscopic movement, once the layers had ruptured; they appear to be the consequence of the post-rupture rock movements related to the intense deformation of the cavity roof. Moreover the analysis shows the presence of some interesting precursory signals before the cavity collapsed. They occurred a few hours before the failure phases, when the rocks were being weakened and damaged. They originated from the damaging and breaking process, when micro-cracks appear and then coalesce. From these results we expect that deeper signal analysis and statistical analysis on the complete event time distribution (several millions of files) will allow us to finalize a complete typology of each signal families and their relations with the evolution steps of the cavity over the five years monitoring.

Mapping Local Protein Electrostatics by EPR of pH-Sensitive Thiol-Specific Nitroxide† ¶

PubMed Central

Voinov, Maxim A.; Ruuge, Andres; Reznikov, Vladimir A.; Grigor’ev, Igor A.; Smirnov, Alex I.

2013-01-01

A first thiol-specific pH-sensitive nitroxide spin label of the imidazolidine series -methanethiosulfonic acid S-(1-oxyl-2,2,3,5,5-pentamethylimidazolidin-4-ylmethyl) ester (IMTSL) - has been synthesized and characterized. X- (9 GHz) and W-band (94 GHz) EPR spectral parameters of the new spin label in its free form and covalently attached to an amino acid cysteine and a tripeptide glutathione were studied as a function of pH and solvent polarity. pKa value of protonatable tertiary amino group of the spin label was found to be unaffected by other ionizable groups present in side chains of unstructured small peptides. The W-band EPR spectra were shown to allow for pKa determination from precise g-factor measurements. Is has been demonstrated that high accuracy of pKa determination for pH-sensitive nitroxides could be achieved regardless the frequency of measurements or the regime of spin exchange: fast at X-band and slow at W-band. IMTSL was found to react specifically with a model protein - iso-1-cytochrome c from yeast Saccharomyces cerevisiae - giving EPR spectra very similar to those of the most commonly employed cysteine-specific label MTSL. CD data indicated no perturbations to the overall protein structure upon IMTSL labeling. It was found that for IMTSL, giso correlates linearly with Aiso but the slopes are different for the neutral and charged forms of the nitroxide. This finding was attributed to the solvent effects on the spin density at the oxygen atom of the N–O group and on the excitation energy of the oxygen lone-pair orbital. PMID:18426227

Geophysical observations at cavity collapse

NASA Astrophysics Data System (ADS)

Jousset, Philippe; Bazargan-Sabet, Behrooz; Lebert, François; Bernardie, Séverine; Gourry, Jean-Christophe

2010-05-01

In Lorraine region (France) salt layers at about 200 meters depth are exploited by Solvay using solution mining methodology which consists in extracting the salt by dissolution, collapsing the cavern overburden during the exploitation phase and finally reclaiming the landscape by creating a water area. In this process, one of the main challenges for the exploiting company is to control the initial 120-m diameter collapse so as to minimize possible damages. In order to detect potential precursors and understand processes associated with such collapses, a wide series of monitoring techniques including micro seismics, broad-band seismology, hydro-acoustic, electromagnetism, gas probing, automatic leveling, continuous GPS, continuous gravity and borehole extensometry was set-up in the frame of an in-situ study carried out by the "Research Group for the Impact and Safety of Underground Works" (GISOS, France). Equipments were set-up well before the final collapse, giving a unique opportunity to analyze a great deal of information prior to and during the collapse process which has been successfully achieved on February the 13th, 2009 by controlling the cavity internal pressure. In this work, we present the results of data recorded by a network of 3 broadband seismometers, 2 accelerometers, 2 tilt-meters and a continuously gravity meter. We relate the variations of the brine pumping rate with the evolutions of the induced geophysical signals and finally we propose a first mechanical model for describing the controlled collapse. Beyond the studied case, extrapolation of the results obtained might contribute to the understanding of uncontrolled cavity collapses, such as pit-craters or calderas at volcanoes.

Local distortion and EPR parameters of copper(II) in borate glasses

NASA Astrophysics Data System (ADS)

Kuang, Min-Quan; Wang, Li-Dan; Duan, Shu-Kai

2017-12-01

The EPR parameters (g and A tensors) of the paramagnetic Cu2+ sites in CaB4O7, LiCaBO3, Li2B4O7, KLiB4O7 glasses are well explained by utilizing the fourth-order perturbation formulas for 3 d9 ions in the tetragonally elongated octahedral [CuO6]10- clusters. The magnitude of the local distortion for the [CuO6]10- clusters suffering the Jahn-Teller effect is denoted by the relative elongation ratio ρ which is proportional to the ratio Δg///Δg⊥ (Δg//= g//-gs and Δg⊥ = g⊥-gs). The g isotropies giso (=(g//+2g⊥)/3) undergo an linear increase with the decline of the covalecny of the glass systems (i.e., the augment of the orbital reduction factor k). The signs of the hyperfine structure constants are determined by computing the quantitative contributions arising from the isotropic and anisotropic copper 3d-3s (4s) orbital admixtures indicated by the core polarization constant κ and the reduction factor H, respectively. The above correlations are proved to be available for analogous borate glasses doping with copper ions, e.g., MRbB4O7 (M = Li, Na and K), 90M2B4O7·9PbO·CuO (M = Li, Na and K), 10MO·30ZnO·60B2O3 (M = Mg, Ca and Sr) and xLi2O·(30-x)Na2O·69.5B2O3 (5 ≤ x ≤ 25 mol%), and all the results are discussed.

Source mechanisms of a collapsing solution mine cavity

NASA Astrophysics Data System (ADS)

Lennart Kinscher, Jannes; Cesca, Simone; Bernard, Pascal; Contrucci, Isabelle; Mangeney, Anne; Piguet, Jack Pierre; Bigarre, Pascal

2016-04-01

The development and collapse of a ~200 m wide salt solution mining cavity was seismically monitored in the Lorraine basin in northeastern France. Seismic monitoring and other geophysical in situ measurements were part of a large multi-parameter research project founded by the research "group for the impact and safety of underground works" (GISOS), whose database is being integrated in the EPOS platform (European Plate Observing System). The recorded microseismic events (~ 50,000 in total) show a swarm-like behaviour, with clustering sequences lasting from seconds to days, and distinct spatiotemporal migration. The majority of swarming signals are likely related to detachment and block breakage processes, occurring at the cavity roof. Body wave amplitude patterns indicate the presence of relatively stable source mechanisms, either associated with dip-slip and/or tensile faulting. However, short inter-event times, the high frequency geophone recordings, and the limited network station coverage often limits the application of classical source analysis techniques. In order to deal with these shortcomings, we examined the source mechanisms through different procedures including modelling of observed and synthetic waveforms and amplitude spectra of some well located events, as well as modelling of peak-to-peak amplitude ratios for most of the detected events. The latter approach was used to infer the average source mechanism of many swarming events at once by using a single three component station. To our knowledge this approach is applied here for the first time and represents an useful tool for source studies of seismic swarms and seismicity clusters. The results of the different methods are consistent and show that at least 50 % of the microseismic events have remarkably stable source mechanisms, associated with similarly oriented thrust faults, striking NW-SE and dipping around 35-55°. Consistent source mechanisms are probably related to the presence of a

Redox and complexation chemistry of the CrVI/CrV-D-glucaric acid system.

PubMed

Mangiameli, María Florencia; González, Juan Carlos; Bellú, Sebastián; Bertoni, Fernando; Sala, Luis F

2014-06-28

When an excess of uronic acid over Cr(VI) is used, the oxidation of D-glucaric acid (Glucar) by Cr(VI) yields D-arabinaric acid, CO2 and Cr(III)-Glucar complex as final redox products. The redox reaction involves the formation of intermediate Cr(IV) and Cr(V) species. The reaction rate increases with [H(+)] and [substrate]. The experimental results indicated that Cr(IV) and Cr(V) are very reactive intermediates since their disappearance rates are much faster than Cr(VI). Cr(IV) and Cr(V) intermediates are involved in fast steps and do not accumulate in the redox reaction of the mixture Cr(VI)-Glucar. Kinetic studies show that the redox reaction between Glucar and Cr(VI) proceeds through a mechanism combining one- and two-electron pathways: Cr(VI) → Cr(IV) → Cr(II) and Cr(VI) → Cr(IV) → Cr(III). After the redox reaction, results show a slow hydrolysis of the Cr(III)-Glucar complex into [Cr(OH2)6](3+). The proposed mechanism is supported by the observation of free radicals, CrO2(2+) (superoxo-Cr(III) ion) and oxo-Cr(V)-Glucar species as reaction intermediates. The continuous-wave electron paramagnetic resonance, CW-EPR, spectra show that five-coordinate oxo-Cr(V) bischelates are formed at pH ≤ 4 with the aldaric acid bound to oxo-Cr(V) through the carboxylate and the α-OH group. A different oxo-Cr(V) species with Glucar was detected at pH 6.0. The high g(iso) value for the last species suggests a mixed coordination species, a five-coordinated oxo-Cr(V) bischelate with one molecule of Glucar acting as a bi-dentate ligand, using the 2-hydroxycarboxylate group, and a second molecule of Glucar with any vic-diolate sites. At pH 7.5 only a very weak EPR signal was observed, which may point to instability of these complexes. This behaviour contrasts with oxo-Cr(V)-uronic species, and must thus be related to the Glucar acyclic structure. In vitro, our studies on the chemistry of oxo-Cr(V)-Glucar complexes can provide information on the nature of the species that

Influence of mixed thiolate/thioether versus dithiolate coordination on the accessibility of the uncommon +I and +III oxidation states for the nickel ion: an experimental and computational study.

PubMed

Gennari, Marcello; Orio, Maylis; Pécaut, Jacques; Bothe, Eberhard; Neese, Frank; Collomb, Marie-Noëlle; Duboc, Carole

2011-04-18

. The g(iso) value is larger than 2.0, which is consistent with metal based oxidation. The unpaired electron (Ni(III), d(7) configuration) occupies a Ni-d(z(2)) based molecular orbital, consistent with DFT calculations. Nitrogen hyperfine structure is observed as a triplet in the g(z) component of the EPR spectrum with A(N) = 51 MHz. This result indicates the coordination of a CH(3)CN molecule in the axial position. DFT calculations confirm that the presence of a fifth ligand in the coordination sphere of the Ni ion is required for the metal-based oxidation process. Finally, we have shown that 1 exhibits catalytic reductive dehalogenation activity below potentials of -2.00 V versus Fc/Fc(+) in CH(2)Cl(2).

Models for aerobic carbon monoxide dehydrogenase: synthesis, characterization and reactivity of paramagnetic MoVO(μ-S)CuI complexes† †Electronic supplementary information (ESI) available: Synthetic yields and microanalytical, mass spectrometric and IR spectroscopic data for all new compounds. CCDC 1576257–1576260. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04239f

PubMed Central

Gourlay, Craig; Nielsen, David J.; Evans, David J.; White, Jonathan M.

2017-01-01

Reaction of [CoCp2][TpiPrMoOS(OAr)] [Cp = η5-cyclopentadienyl; TpiPr = hydrotris(3-isopropylpyrazol-1-yl)borate; OAr = phenolate or derivative thereof] with [Cu(NCMe)(Me3tcn)]BF4 (Me3tcn = 1,4,7-trimethyl-1,4,7-triazacyclononane) in MeCN at –30 °C results in the formation of red-brown/black, paramagnetic, μ-sulfido-Mo(v)/Cu(i) complexes, TpiPrMoO(OAr)(μ-S)Cu(Me3tcn). The complexes possess the MoO(μ-S)Cu core found in aerobic carbon monoxide dehydrogenases (CODHs) and exhibit X-band EPR spectra closely related to those of semi-reduced CODH, with giso ∼ 1.937, hyperfine coupling to 95,97Mo (aiso = 39–42 × 10–4 cm–1) and strong superhyperfine coupling to 63,65Cu (aiso = 34–63 × 10–4 cm–1). Anisotropic spectra exhibit monoclinic symmetry with g1 ∼ 1.996, g2 ∼ 1.944 and g3 ∼ 1.882, and nearly isotropic ACu values (75–90 × 10–4 cm–1). The X-ray structures of four derivatives (Ar = Ph, C6H4tBu-2, C6H4sBu-2, C6H4Ph-4) are reported and discussed along with that of the Ar = C6H3tBu2-3,5 derivative (communicated in C. Gourlay, D. J. Nielsen, J. M. White, S. Z. Knottenbelt, M. L. Kirk and C. G. Young, J. Am. Chem. Soc., 2006, 128, 2164). The complexes exhibit distorted octahedral oxo-Mo(v) and distorted tetrahedral Cu(i) centres bridged by a single bent μ-sulfido ligand, with Mo–S and Cu–S distances and Mo–S–Cu angles in the ranges 2.262–2.300 Å, 2.111–2.134 Å and 115.87–134.27°, respectively. The 2 t-butyl derivative adopts a unique phenolate conformation with O 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000

9,10-phenanthrenesemiquinone radical complexes of ruthenium(III), osmium(III) and rhodium(III) and redox series.

PubMed

Biswas, Manas Kumar; Patra, Sarat Chandra; Maity, Amarendra Nath; Ke, Shyue-Chu; Weyhermüller, Thomas; Ghosh, Prasanta

2013-05-14

parameters well prompting the coordination of PQ(˙-) to the M(III) ions. The comparatively shorter C-O lengths, 1.268(4) and 1.266(5) Å and the longer C-C length, 1.466(6) Å, are consistent with the PQ chelation to osmium(II) ion in 4(+). The reversible anodic waves at 0.22, 0.22, and 0.18 V of 1-3, referenced by the Fc(+)/Fc couple, are assigned to the PQ(˙-)/PQ couple forming PQ complexes as trans/cis-[M(III)(PQ)(PPh3)2X2](+) while the cathodic waves at -0.92 and -0.89 V of 2 and 3 are due to formations of PQ(2-) complexes as trans-[M(III)(PQ(2-))(PPh3)2X2](-). 1 displays two overlapping cathodic waves at -0.72(89), -1.0(120) V. EPR spectrum of the frozen glass of 1(-) along with DFT calculations detected the contribution of both the valence tautomers, trans-[Ru(III)(PQ(2-))(PPh3)2Cl2](-) (g1 = g2 = 2.456; g3 = 1.983) and trans-[Ru(II)(PQ(˙-))(PPh3)2X2](-) (g(iso) = 1.999) in the anion. The characteristic lower energy absorption bands of 1 and 2 at 700 nm were assigned to CSS-OSS perturbation MLCT those are absent in paramagnetic 3, 1(+), 2(+), 1(-), 2(-) and 4(+) complexes, investigated by spectro-electrochemical measurements and time dependent (TD) DFT calculations on 1Me, 2Me, 1Me(+) and 1Me(-).