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Sample records for psi-sbs4 trigonal bipyramids

  1. The Catalytic Scaffold fo the Haloalkanoic Acid Dehalogenase Enzyme Superfamily Acts as a Mold for the Trigonal Bipyramidal Transition State

    Energy Technology Data Exchange (ETDEWEB)

    Lu,Z.; Dunaway-Mariano, D.; Allen, K.

    2008-01-01

    The evolution of new catalytic activities and specificities within an enzyme superfamily requires the exploration of sequence space for adaptation to a new substrate with retention of those elements required to stabilize key intermediates/transition states. Here, we propose that core residues in the large enzyme family, the haloalkanoic acid dehalogenase enzyme superfamily (HADSF) form a 'mold' in which the trigonal bipyramidal transition states formed during phosphoryl transfer are stabilized by electrostatic forces. The vanadate complex of the hexose phosphate phosphatase BT4131 from Bacteroides thetaiotaomicron VPI-5482 (HPP) determined at 1.00 Angstroms resolution via X-ray crystallography assumes a trigonal bipyramidal coordination geometry with the nucleophilic Asp-8 and one oxygen ligand at the apical position. Remarkably, the tungstate in the complex determined to 1.03 Angstroms resolution assumes the same coordination geometry. The contribution of the general acid/base residue Asp-10 in the stabilization of the trigonal bipyramidal species via hydrogen-bond formation with the apical oxygen atom is evidenced by the 1.52 Angstroms structure of the D10A mutant bound to vanadate. This structure shows a collapse of the trigonal bipyramidal geometry with displacement of the water molecule formerly occupying the apical position. Furthermore, the 1.07 Angstroms resolution structure of the D10A mutant complexed with tungstate shows the tungstate to be in a typical 'phosphate-like' tetrahedral configuration. The analysis of 12 liganded HADSF structures deposited in the protein data bank (PDB) identified stringently conserved elements that stabilize the trigonal bipyramidal transition states by engaging in favorable electrostatic interactions with the axial and equatorial atoms of the transferring phosphoryl group.

  2. Substitutions into the trigonal bipyramidal site of InGaCuO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Grajczyk, Rosa, E-mail: rabinovr@onid.orst.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Biswas, Krishnendu, E-mail: krismat79@gmail.com [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Berthelot, Romain, E-mail: berthelr@science.oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Li, Jun, E-mail: jli100@yahoo.com [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Sleight, A.W., E-mail: arthur.sleight@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Subramanian, M.A., E-mail: mas.subramanian@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States)

    2012-03-15

    Solid solutions of InMCu{sub 1-x}Mg{sub x}O{sub 4} (M=Ga{sup 3+}, Al{sup 3+}) have been synthesized to understand the influence of the trigonal bipyramidal (TBP) crystallographic M{sup 3+}/Cu{sup 2+} site of the YbFe{sub 2}O{sub 4}-type structure through powder X-ray and neutron diffraction, dielectric and magnetism measurements. The addition of Mg{sup 2+} in the InGaCuO{sub 4} lattice results in a decrease of the dielectric constant, but the dielectric loss is not affected until the concentration of Mg{sup 2+} is above x=0.50. The shift in the diffraction peaks, and subsequently the change in the lattice parameters, cannot be exclusively explained by the change in ionic radii. These results show the first observation of the reduction in axial bond lengths for TBP Cu{sup 2+} in a YbFe{sub 2}O{sub 4}-type crystal lattice. - Graphical abstract: Solid solutions of InMCu{sub 1-x}Mg{sub x}O{sub 4} (M=Ga{sup 3+}, Al{sup 3+}) have been synthesized and analyzed with powder X-ray and neutron diffraction, dielectric and magnetism measurements. A shift in the lattice parameters that cannot be explained by the change in ionic radii is addressed through a study of the trigonal bipyramidal site. Highlights: Black-Right-Pointing-Pointer Solid solutions of InMCu{sub 1-x}Mg{sub x}O{sub 4} (M=Ga{sup 3+}, Al{sup 3+}) have been synthesized. Black-Right-Pointing-Pointer The observed dielectric properties decreased with the dilution of Cu{sup 2+}. Black-Right-Pointing-Pointer Antiferromagnetic interactions, without ordering, were observed in InGaCu{sub 1-x}Mg{sub x}O{sub 4}. Black-Right-Pointing-Pointer A reduction in the axial TBP bond lengths produced a large change in the c/a ratio. Black-Right-Pointing-Pointer Orbital overlap across the TBP layers greatly affected the observed properties.

  3. Ground state properties of trigonal prismatic and trigonal bipyramidal d1,9, d2,8, d3,7, and d5 systems: Effects of trigonal distortion

    Science.gov (United States)

    Hempel, Judith C.; Miller, Michael E.

    1981-09-01

    Empirical ligand field theory has been used to calculate ground state energy space diagrams for d1,9, d2,8, d3,7, and d5 systems of D3h symmetry and allowed ground states for trigonal bipyramidal (five coordinate) and trigonal prismatic (six coordinate) D3h geometries have been identified. We demonstrate that entirely similar behavior should be expected for trigonal prismatic and trigonal bipyramidal d5 systems. Spin-orbit calculations complete within the d5 basis are used to establish that the ESR zero field parameter D for a 6A'1(D3h) ground state will normally be negative. Normalized spherical harmonic (NSH) ligand field Hamiltonians symmetry adapted to chains based on the D6h covering group are defined for all trigonal symmetries. Multiple symmetry parameter sets, which arise for trigonal symmetries other than D3h, describe the range of orbital mixing possible. Spin-orbit and Zeeman interactions reveal the effects of orbital mixing and restrict to two the number of symmetry parameter sets possible for a trigonal system. We specifically consider the magnetic properties of the five coordinate complexes of C3v symmetry [M(Me6tren)Br]Br, with M = Cu(II) and Ni(II) using calculations for C3v symmetry which incorporate spin-orbit and Zeeman interactions and are complete within the dn basis.

  4. Structural Dependence of the Ising-type Magnetic Anisotropy and of the Relaxation Time in Mononuclear Trigonal Bipyramidal Co(II) Single Molecule Magnets.

    Science.gov (United States)

    Shao, Feng; Cahier, Benjamin; Rivière, Eric; Guillot, Régis; Guihéry, Nathalie; Campbell, Victoria E; Mallah, Talal

    2017-02-06

    This paper describes the correlation between Ising-type magnetic anisotropy and structure in trigonal bipyramidal Co(II) complexes. Three sulfur-containing trigonal bipyramidal Co(II) complexes were synthesized and characterized. It was shown that we can engineer the magnitude of the Ising anisotropy using ligand field theory arguments in conjunction with structural parameters. To prepare this series of compounds, we used, on the one hand, a tetradentate ligand containing three sulfur atoms and one amine (NS3tBu) and on the other hand three different axial ligands, namely, Cl-, Br-, and NCS-. The organic ligand imposes a trigonal bipyramidal arrangement with the three sulfur atoms lying in the trigonal plane with long Co-S bond distances. The magnetic properties of the compounds were measured, and ab initio calculations were used to analyze the anisotropy parameters and perform magneto-structural correlations. We demonstrate that a smaller axial zero-field splitting parameter leads to slower relaxation time when the symmetry is strictly axial, while the presence of very weak rhombicity decreases the energy barrier and speeds the relaxation of the magnetization.

  5. Trigonal-Bipyramidal Coordination in First Ammoniates of ZnF2: ZnF2(NH3)3 and ZnF2(NH3)2.

    Science.gov (United States)

    Richter, Theresia M M; LeTonquesse, Sylvain; Alt, Nicolas S A; Schlücker, Eberhard; Niewa, Rainer

    2016-03-07

    Single crystals of ZnF2(NH3)3 and ZnF2(NH3)2 were obtained under ammonothermal conditions (250 °C, 196 MPa and 500 °C, 136 MPa). Upon thermal decomposition of both ZnF2(NH3)3 and ZnF2(NH3)2, a microcrystalline powder of ZnF2(NH3) was obtained. ZnF2(NH3)3 and ZnF2(NH3)2 represent probable intermediates in a conceivable ammonothermal synthesis of the semiconductor Zn3N2 and manifest a rare trigonal-bipyramidal coordination of F(-) and NH3 ligands around Zn(2+) according to single-crystal X-ray diffraction. Thermal analysis of all three compounds showed not only ZnF2(NH3) but also ZnF2(NH3)2 to be decomposition intermediates of ZnF2(NH3)3 prior to the formation of ZnF2. All three compounds demonstrate hydrogen bonds, as indicated by the intensities and half-widths of the bands in the vibrational spectra and by short N-H···F distances in the crystal structures of ZnF2(NH3)3 and ZnF2(NH3)2. With ZnF2(NH3)3, ZnF2(NH3)2, and ZnF2(NH3), we present the first ammoniates of ZnF2.

  6. Moduli of Trigonal Curves

    CERN Document Server

    Stankova-Frenkel, Z E

    1997-01-01

    We study the moduli of trigonal curves. We establish the exact upper bound of ${36(g+1)}/(5g+1)$ for the slope of trigonal fibrations. Here, the slope of any fibration $X\\to B$ of stable curves with smooth general member is the ratio Hodge class $\\lambda$ on the moduli space $\\bar{\\mathfrak{M}}_g$ to the base $B$. We associate to a trigonal family $X$ a canonical rank two vector bundle $V$, and show that for Bogomolov-semistable $V$ the slope satisfies the stronger inequality ${\\delta_B}/{\\lambda_B}\\leq 7+{6}/{g}$. We further describe the rational Picard group of the {trigonal} locus $\\bar{\\mathfrak T}_g$ in the moduli space $\\bar{\\mathfrak{M}}_g$ of genus $g$ curves. In the even genus case, we interpret the above Bogomolov semistability condition in terms of the so-called Maroni divisor in $\\bar{\\mathfrak T}_g$.

  7. Trigon Farming ehitab Kaiu moodsa eurolauda / Heli Talinur

    Index Scriptorium Estoniae

    Talinur, Heli

    2007-01-01

    Trigon Farming tegutseb Eestis aastast 2003 ning firmal on laudad peale Kaiu veel Saaremaal Kärlas, lisaks tegutseb firma ka Venemaal ja Ukrainas. Farmingu emafirma on Trigon Agri, mis on noteeritud Stockholmi börsil

  8. Allan Martinson ja Trigon teevad oma riskikapitalifondi / Kristiina Randmaa

    Index Scriptorium Estoniae

    Randmaa, Kristiina

    2004-01-01

    Investeerimispank Trigon Capital ja infotehnoloogiaettevõte MicroLink endine juht Allan Martinson loovad Martinson Trigon Venture Partners nime all ühise kuni 400 miljoni kroonise mahuga riskikapitalifondi

  9. Trigon Farming ostis Kaiu LT / Margus Mikomägi

    Index Scriptorium Estoniae

    Mikomägi, Margus, 1956-

    2006-01-01

    Raplamaalt suuruselt neljas põllumajandusühistu Kaiu LT müüdi üldkoosoleku otsusega ühel häälel firmale Trigon Farming. Kaiu LT nõukogu esimees on viimased kolm aastat olnud Riigikogu liige Tiit Tammsaar. Lisa: Trigon Tarming investeerib põllumajandusse

  10. Allan Martinson ja Trigon panid käima uue riskikapitalifondi / Kristina Traks

    Index Scriptorium Estoniae

    Traks, Kristina, 1976-

    2005-01-01

    Allan Martinson ja investeerimispank Trigon Capital lõid uue riskikapitaliettevõtte Martinson Trigon Venture Partners, mis hakkab investeerima tehnoloogia-, meedia- ja telekommunikatsioonifirmadesse Balti riikides ja Venemaal

  11. Trigon Capital sukeldub Ukraina piimaärisse / Airi Ilisson

    Index Scriptorium Estoniae

    Ilisson, Airi, 1980-

    2005-01-01

    Investeerimisfirma Trigon Capital valis uueks investeeringute sihiks Ukraina piimatööstuse muutunud poliitilise kliima ja piimatöökvootide puudumise tõttu. Lisa: Kinnisvara. Horvaatia kinnisvaraäri

  12. Higher Genus Abelian Functions Associated with Cyclic Trigonal Curves

    Directory of Open Access Journals (Sweden)

    Matthew England

    2010-03-01

    Full Text Available We develop the theory of Abelian functions associated with cyclic trigonal curves by considering two new cases. We investigate curves of genus six and seven and consider whether it is the trigonal nature or the genus which dictates certain areas of the theory. We present solutions to the Jacobi inversion problem, sets of relations between the Abelian function, links to the Boussinesq equation and a new addition formula.

  13. A holmium(III)-based single-molecule magnet with pentagonal-bipyramidal geometry

    Energy Technology Data Exchange (ETDEWEB)

    Kajiwara, Takashi [Department of Chemistry, Faculty of Science, Nara Women' s University (Japan)

    2017-09-11

    The right environment: The remarkable properties of a recently reported holmium(III)-based single-ion magnet have been ascribed to the hyperfine interactions with the half-integer nuclear spin in combination with the pentagonal-bipyramidal coordination environment. These results provide insight into the complicated magnetic properties of nanosized magnetic materials. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. An anti-ferromagnetic terephthalate-bridged trigonal prismatic ...

    Indian Academy of Sciences (India)

    Each manganese(II) centre adopts a rare distorted trigonal prismatic geometry with an MnN4O2 chromophore.Chelation of the tetradentate Schiff base (L) along with bis(bidentate) bridging of two O atoms of tp complete hexacoordination around each manganese(II) centre. The dinuclear units of 1 are associated through ...

  15. Facile synthesis of mesoporous nanocrystalline ZnO bipyramids and spheres: Characterization, and photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, Priya; Subramanian, Balaji [Laboratoire de recherche en matériaux et Micro-spectroscopies Raman et FTIR, Université de Moncton, Campus de Shippagan, Shippagan, NB, E8S 1P6 Canada (Canada); Djaoued, Yahia, E-mail: yahia.djaoued@umoncton.ca [Laboratoire de recherche en matériaux et Micro-spectroscopies Raman et FTIR, Université de Moncton, Campus de Shippagan, Shippagan, NB, E8S 1P6 Canada (Canada); Robichaud, Jacques [Laboratoire de recherche en matériaux et Micro-spectroscopies Raman et FTIR, Université de Moncton, Campus de Shippagan, Shippagan, NB, E8S 1P6 Canada (Canada); Sharma, Tanu; Bruning, Ralf [Department of Physcis, Mount Alison University, Sackville, NB, E4L 1E6 Canada (Canada)

    2015-04-01

    A facile and versatile polyol mediated solvo-thermal process using zinc acetate has been adopted for the synthesis of mesoporous ZnO nanomaterials having novel morphologies. Polyols used in this study, i.e. ethylene glycol (EG) and polyethylene glycols (PEG) of molecular weight 200 and 400, not only act as solvents but also as structure directing agents. The synthesis using EG leads to the formation of novel square bipyramidal zinc glycolate intermediate, which upon thermal treatment is converted into a nanocrystalline (NC) wurtzite ZnO structure, preserving the square bipyramidal morphology. Zinc glycolate upon hot water treatment (∼85 °C), results in the formation of NC wurtzite ZnO having a bicone morphology. However, when the synthesis is carried out by replacing EG with PEG-200 or 400, NC wurtzite ZnO having spherical morphologies have been directly isolated. In the case of PEG-200, the NC ZnO spheres displayed radially oriented nanorod features on the surface. A mechanism of formation of these ZnO morphologies is proposed. The synthesized ZnO materials have been used as catalysts for the photodegradation of crystal violet dye under UV-B and UV-C irradiation. The catalytic behavior of the ZnO samples is explained based on their porosity, crystallinity, and microstructure. - Highlights: • A polyol facilitated process using zinc acetate was used to obtain mesoporous ZnO. • These mesoporous ZnO materials exhibited square bipyramids and spheres morphologies. • Ethylene glycol and PEG-200 mediated ZnO samples presented higher degradation rates. • Crystallinity takes precedence over surface area in photodegradation.

  16. Shaping Gold Nanocrystals in Dimethyl Sulfoxide: Toward Trapezohedral and Bipyramidal Nanocrystals Enclosed by {311} Facets.

    Science.gov (United States)

    Niu, Wenxin; Duan, Yukun; Qing, Zikun; Huang, Hejin; Lu, Xianmao

    2017-04-26

    The remarkable synthetically tunable structural, electronic, and optical properties of gold nanocrystals have attracted increasing interest and enabled multidisciplinary applications. Over the past decades, nearly all the possible fundamental shapes of faceted Au nanocrystals have been synthesized, except for only one missing-the trapezohedron enclosed by {hkk} facets. In this report, the unprecedented synthesis of trapezohedral Au nanocrystals with {311} crystal facets was realized. Dimethyl sulfoxide (DMSO) was discovered as a solvent for shaping Au nanocrystals with {311} crystal facets for the first time. Mechanistic studies, together with previous DFT and STM studies, attribute the unique role of DMSO to its ambidentate nature, where both sulfur and oxygen of DMSO can coordinate to gold surface, endowing its unique role in stabilizing high-index {311} facets through a "two center bonding" mode. The DMSO-based synthesis provides a new synthetic tool toward the synthesis of a series of unreported Au nanocrystals with new structures. In particular, a new type of gold bipyramids, the octagonal bipyramids, was first synthesized with additional plasmonic tunability while simultaneously retaining their {311} facets. The application of these new Au nanocrystals in surface-enhanced Raman scattering spectroscopy was investigated, and their shape-dependent performances were demonstrated. These results highlight the tremendous potential of using ambidentate molecules as shape- and surface-directing agents for metal nanocrystals and offer the promise of enabling new synthetic tools toward atomically precise control of surface structures of metal nanocrystals.

  17. Synthesis of gold hexagonal bipyramids directed by planar-twinned silver triangular nanoprisms.

    Science.gov (United States)

    Personick, Michelle L; Langille, Mark R; Wu, Jinsong; Mirkin, Chad A

    2013-03-13

    The direct growth of planar-twinned Au nanoparticles (NPs) in high yield remains a challenge in shape-controlled NP synthesis largely because suitable planar-twinned seeds for Au NP growth have not been identified to date. Herein we describe the use of planar-twinned Ag triangular nanoprisms as a means to dictate Au NP twin structure. In a one-pot process, the Ag triangular nanoprisms first undergo oxidative Au replacement, forming Ag-Au alloy nanoframes and concomitantly releasing Ag(+) into solution, which then directs subsequent Au NP growth through an underpotential deposition process. The planar-twinned structure of the initial Ag nanoprism is maintained throughout particle growth. Using this method, we have successfully synthesized Au hexagonal bipyramids in high yield for the first time.

  18. Trigonal crystals of glucose isomerase require thymol for their growth and stability

    Science.gov (United States)

    Chayen, N. E.; Lloyd, L. F.; Collyer, C. A.; Blow, D. M.

    1989-09-01

    The growth of trigonal bypyramidal crystals of Arthrobacter glucose isomerase is only possible in the presence of thymol at a concentration exceeding 2.5mM; at lower thymol concentrations rectangular and rhombic crystals are formed. When thymol is removed from the supernatant of trigonal crystals, they fall apart and recrystallise as rectangles or rhombs. The disordering can be reversed if thymol is reintroduced before the trigonal crystals have dispersed, but the other crystal forms are stable in thymol. During the disintegration of trigonal crystals the supernatant concentration of protein is increased.

  19. Development of hybrid mass damper (TRIGON) for high-rise buildings; Chokoso biruyo hybrid mass damper (TRIGON) no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-10-31

    The hybrid mass damper TRIGON has been developed to reduce wind-and earthquake-induced vibrations of high-rise buildings. The present paper describes an experimental result executed to confirm the outline of the hybrid mass damper TRIGON and the control effect of the same. The present apparatus is a mass damper for reducing the response of a building by supporting a weight with a V shaped bottom with a roller and rocking the weight into a pendulum motion. A driving method is a hybrid one where there are both used a passive system in which an apparatus period defined by the angle of the weight bottom is tuned with a building period and an active system using an AC servo motor. It is further intended that the apparatus is made compact by neglecting the length of the pendulum by employing the V-shaped weight for supporting the roller. Building vibration tests are conducted to compare responses of the apparatus upon non-control and control. It is hereby confirmed that there can be added about 4 % of a damping factor of the first mode in the direction of the short side of the building as a control object for a satisfactory improvement of the dwelling property. 4 refs., 14 figs., 3 tabs.

  20. Prospective randomised controlled trial comparing trigone-sparing versus trigone-including intradetrusor injection of abobotulinumtoxinA for refractory idiopathic detrusor overactivity.

    LENUS (Irish Health Repository)

    Manecksha, Rustom P

    2012-05-01

    Botulinum toxin A is effective for treatment of idiopathic detrusor overactivity (IDO). The trigone is generally spared because of the theoretical risk of vesicoureteric reflux (VUR), although studies assessing injection sites are lacking.

  1. Orientation sensors by defocused imaging of single gold nano-bipyramids

    Science.gov (United States)

    Zhang, Fanwei; Li, Qiang; Rao, Wenye; Hu, Hongjin; Gao, Ye; Wu, Lijun

    2018-01-01

    Optical probes for nanoscale orientation sensing have attracted much attention in the field of single-molecule detections. Noble metal especially Au nanoparticles (NPs) exhibit extraordinary plasmonic properties, great photostability, excellent biocompatibility and nontoxicity, and thereby could be alternative labels to conventional applied organic dyes or quantum dots. One type of the most interesting metallic NPs is Au nanorods (AuNRs). Its anisotropic emission accompanied with anisotropic shape is potentially applicable in orientation sensing. Recently, we resolved the 3D orientation of single AuNRs within one frame by deliberately introducing an aberration (slight shift of the dipole away from the focal plane) to the imaging system1 . This defocused imaging technique is based on the electron transition dipole approximation and the fact that the dipole radiation exhibits an angular anisotropy. Since the photoluminescence quantum yield (PLQY) can be enhanced by the "lightning rod effect" (at a sharp angled surface) and localized SPR modes, that of the single Au nano-bipyramid (AuNB) with more sharp tips or edges was found to be doubled comparing to AuNRs with a same effective size2. Here, with a 532 nm excitation, we find that the PL properties of individual AuNBs can be described by three perpendicularly-arranged dipoles (with different ratios). Their PL defocused images are bright, clear and exhibit obvious anisotropy. These properties suggest that AuNBs are excellent candidates for orientation sensing labels in single molecule detections.

  2. Pentagonal Bipyramid FeII Complexes: Robust Ising-Spin Units towards Heteropolynuclear Nanomagnets.

    Science.gov (United States)

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

    2017-03-28

    Pentagonal bipyramid FeII complexes have been investigated to evaluate their potential as Ising-spin building units for the preparation of heteropolynuclear complexes that are likely to behave as single-molecule magnets (SMMs). The considered monometallic complexes were prepared from the association of a divalent metal ion with pentadentate ligands that have a 2,6-diacetylpyridine bis(hydrazone) core (H2 LN3O2R ). Their magnetic anisotropy was established by magnetometry to reveal their zero-field splitting (ZFS) parameter D, which ranged between -4 and -13 cm-1 and was found to be modulated by the apical ligands (ROH versus Cl). The alteration of the D value by N-bound axial CN ligands, upon association with cyanometallates, was also assessed for heptacoordinated FeII as well as for related NiII and CoII derivatives. In all cases, N-coordinated cyanide ligands led to large magnetic anisotropy (i.e., -8 to -18 cm-1 for Fe and Ni, +33 cm-1 for Co). Ab initio calculations were performed on three FeII complexes, which enabled one to rationalize the role of the ligand on the nature and magnitude of the magnetic anisotropy. Starting from the pre-existing heptacoordinated complexes, a series of pentanuclear compounds were obtained by reactions with paramagnetic [W(CN)8 ]3- . Magnetic studies revealed the occurrence of ferromagnetic interactions between the spin carriers in all the heterometallic systems. Field-induced slow magnetic relaxation was observed for mononuclear FeII complexes (Ueff /kB up to 53 K (37 cm-1 ), τ0 =5×10-9  s), and SMM behavior was evidenced for a heteronuclear [Fe3 W2 ] derivative (Ueff /kB =35 K and τ0 =4.6 10-10  s), which confirmed that the parent complexes were robust Ising-type building units. High-field EPR spectroscopic investigation of the ZFS parameters for a Ni derivative is also reported. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Direct observation of the core/double-shell architecture of intense dual-mode luminescent tetragonal bipyramidal nanophosphors.

    Science.gov (United States)

    Kim, Su Yeon; Jeong, Jong Seok; Mkhoyan, K Andre; Jang, Ho Seong

    2016-05-21

    Highly efficient downconversion (DC) green-emitting LiYF4:Ce,Tb nanophosphors have been synthesized for bright dual-mode upconversion (UC) and DC green-emitting core/double-shell (C/D-S) nanophosphors-Li(Gd,Y)F4:Yb(18%),Er(2%)/LiYF4:Ce(15%),Tb(15%)/LiYF4-and the C/D-S structure has been proved by extensive scanning transmission electron microscopy (STEM) analysis. Colloidal LiYF4:Ce,Tb nanophosphors with a tetragonal bipyramidal shape are synthesized for the first time and they show intense DC green light via energy transfer from Ce(3+) to Tb(3+) under illumination with ultraviolet (UV) light. The LiYF4:Ce,Tb nanophosphors show 65 times higher photoluminescence intensity than LiYF4:Tb nanophosphors under illumination with UV light and the LiYF4:Ce,Tb is adapted into a luminescent shell of the tetragonal bipyramidal C/D-S nanophosphors. The formation of the DC shell on the core significantly enhances UC luminescence from the UC core under irradiation of near infrared light and concurrently generates DC luminescence from the core/shell nanophosphors under UV light. Coating with an inert inorganic shell further enhances the UC-DC dual-mode luminescence by suppressing the surface quenching effect. The C/D-S nanophosphors show 3.8% UC quantum efficiency (QE) at 239 W cm(-2) and 73.0 ± 0.1% DC QE. The designed C/D-S architecture in tetragonal bipyramidal nanophosphors is rigorously verified by an energy dispersive X-ray spectroscopy (EDX) analysis, with the assistance of line profile simulation, using an aberration-corrected scanning transmission electron microscope equipped with a high-efficiency EDX. The feasibility of these C/D-S nanophosphors for transparent display devices is also considered.

  4. Nucleation-mediated synthesis and enhanced catalytic properties of Au-Pd bimetallic tripods and bipyramids with twinned structures and high-energy facets

    Science.gov (United States)

    Zhang, Lei; Chen, Qiaoli; Wang, Xue; Jiang, Zhiyuan

    2016-01-01

    The Au-Pd alloy has been proved to be an excellent catalyst in many applications, such as the electro-oxidation of formic acid, CO oxidation and oxidation of alcohols to aldehydes. However, most of the research has been focused on the shape-controlled Au-Pd alloy NCs with a single-crystal structure. Due to the existence of high-energy atoms on the twin defects, twinned structures usually will further increase their catalytic activities. It is necessary to develop a method to prepare the Au-Pd alloy with twinned structures and investigate their catalytic properties. Herein, we successfully synthesized Au-Pd alloy tripods and bipyramids with twinned structures by the cooperation of cetyltrimethyl ammonium chloride (CTAC) and cetyltrimethyl ammonium bromide (CTAB). The tripods contain one twin plane, while the bipyramids consist of a fivefold-twinned structure. In addition, the tripods and bipyramids are both exposed by high-energy facets. We proposed that the tripods and bipyramids are evolved from bipyramid seeds and fivefold twinned seeds, respectively. The as-prepared Au-Pd tripods and bipyramids performed better activity for electrocatalytic oxidation of formic acid compared to the cubic Au-Pd nanoparticles.The Au-Pd alloy has been proved to be an excellent catalyst in many applications, such as the electro-oxidation of formic acid, CO oxidation and oxidation of alcohols to aldehydes. However, most of the research has been focused on the shape-controlled Au-Pd alloy NCs with a single-crystal structure. Due to the existence of high-energy atoms on the twin defects, twinned structures usually will further increase their catalytic activities. It is necessary to develop a method to prepare the Au-Pd alloy with twinned structures and investigate their catalytic properties. Herein, we successfully synthesized Au-Pd alloy tripods and bipyramids with twinned structures by the cooperation of cetyltrimethyl ammonium chloride (CTAC) and cetyltrimethyl ammonium bromide (CTAB

  5. Direct observation of the core/double-shell architecture of intense dual-mode luminescent tetragonal bipyramidal nanophosphors

    Science.gov (United States)

    Kim, Su Yeon; Jeong, Jong Seok; Mkhoyan, K. Andre; Jang, Ho Seong

    2016-05-01

    Highly efficient downconversion (DC) green-emitting LiYF4:Ce,Tb nanophosphors have been synthesized for bright dual-mode upconversion (UC) and DC green-emitting core/double-shell (C/D-S) nanophosphors--Li(Gd,Y)F4:Yb(18%),Er(2%)/LiYF4:Ce(15%),Tb(15%)/LiYF4--and the C/D-S structure has been proved by extensive scanning transmission electron microscopy (STEM) analysis. Colloidal LiYF4:Ce,Tb nanophosphors with a tetragonal bipyramidal shape are synthesized for the first time and they show intense DC green light via energy transfer from Ce3+ to Tb3+ under illumination with ultraviolet (UV) light. The LiYF4:Ce,Tb nanophosphors show 65 times higher photoluminescence intensity than LiYF4:Tb nanophosphors under illumination with UV light and the LiYF4:Ce,Tb is adapted into a luminescent shell of the tetragonal bipyramidal C/D-S nanophosphors. The formation of the DC shell on the core significantly enhances UC luminescence from the UC core under irradiation of near infrared light and concurrently generates DC luminescence from the core/shell nanophosphors under UV light. Coating with an inert inorganic shell further enhances the UC-DC dual-mode luminescence by suppressing the surface quenching effect. The C/D-S nanophosphors show 3.8% UC quantum efficiency (QE) at 239 W cm-2 and 73.0 +/- 0.1% DC QE. The designed C/D-S architecture in tetragonal bipyramidal nanophosphors is rigorously verified by an energy dispersive X-ray spectroscopy (EDX) analysis, with the assistance of line profile simulation, using an aberration-corrected scanning transmission electron microscope equipped with a high-efficiency EDX. The feasibility of these C/D-S nanophosphors for transparent display devices is also considered.Highly efficient downconversion (DC) green-emitting LiYF4:Ce,Tb nanophosphors have been synthesized for bright dual-mode upconversion (UC) and DC green-emitting core/double-shell (C/D-S) nanophosphors--Li(Gd,Y)F4:Yb(18%),Er(2%)/LiYF4:Ce(15%),Tb(15%)/LiYF4--and the C/D-S structure

  6. On projective varieties admitting a bielliptic or trigonal curve-section

    Directory of Open Access Journals (Sweden)

    Andrea Del Centina

    1993-05-01

    Full Text Available We study smooth projective varieties X ⊆ PN of dimension n ≥ 3, such that for some linear (N-n+1-dimensional space Π ⊆ PN, C=X∩Π is either a bielliptic or a trigonal curve. We give a description of X when deg ≥ 18 and when deg X ≤ 8.

  7. On projective varieties admitting a bielliptic or trigonal curve-section

    OpenAIRE

    Andrea Del Centina; Alessandro Gimigliano

    1993-01-01

    We study smooth projective varieties X ⊆ PN of dimension n ≥ 3, such that for some linear (N-n+1)-dimensional space Π ⊆ PN, C=X∩Π is either a bielliptic or a trigonal curve. We give a description of X when deg ≥ 18 and when deg X ≤ 8.

  8. 'Trigonal' @iDiscocyclina@@ sp. from the Pondicherry formation, Pondicherry, South India

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    of this species is chiefly planktonic, and transitional from the Discocyclinid limestone unit to the Upper marlstone unit, as seen by a lesser degree of abundance. The 'trigonal' shape of the test may be due either to specialisation or degeneration in the changed...

  9. Origin and spectroscopic determination of trigonal anisotropy in a heteronuclear single-molecule magnet

    Science.gov (United States)

    Sorace, L.; Boulon, M.-E.; Totaro, P.; Cornia, A.; Fernandes-Soares, J.; Sessoli, R.

    2013-09-01

    W-band (ν ≅ 94 GHz) electron paramagnetic resonance (EPR) spectroscopy was used for a single-crystal study of a star-shaped Fe3Cr single-molecule magnet (SMM) with crystallographically imposed trigonal symmetry. The high resolution and sensitivity accessible with W-band EPR allowed us to determine accurately the axial zero-field splitting terms for the ground (S = 6) and first two excited states (S = 5 and S = 4). Furthermore, spectra recorded by applying the magnetic field perpendicular to the trigonal axis showed a π/6 angular modulation. This behavior is a signature of the presence of trigonal transverse magnetic anisotropy terms whose values had not been spectroscopically determined in any SMM prior to this work. Such in-plane anisotropy could only be justified by dropping the so-called “giant spin approach” and by considering a complete multispin approach. From a detailed analysis of experimental data with the two models, it emerged that the observed trigonal anisotropy directly reflects the structural features of the cluster, i.e., the relative orientation of single-ion anisotropy tensors and the angular modulation of single-ion anisotropy components in the hard plane of the cluster. Finally, since high-order transverse anisotropy is pivotal in determining the spin dynamics in the quantum tunneling regime, we have compared the angular dependence of the tunnel splitting predicted by the two models upon application of a transverse field (Berry-phase interference).

  10. Pseudomembranous trigonitis in a male with Klinefelter syndrome: a case report and evidence of a hormonal etiology.

    Science.gov (United States)

    Lian, Derrick W Q; Li, Fay X; Ong, Caroline C P; Kuick, C H; Chang, Kenneth T E

    2014-01-01

    Klinefelter syndrome is a clinical syndrome with a distinct 47, XXY karyotype. Patients are characterized by a tall eunuchoid stature, small testes, hypergonotrophic hypogonadism, gynecomastia, learning difficulties and infertility. These patients have also been found to have raised estrogen levels. We report a 16 year old boy with Klinefelter syndrome presenting to our institution with gross hematuria. Cystoscopy and biopsy revealed the diagnosis of pseudomembranous trigonitis. Immunohistochemical stains showed an increase in estrogen and progesterone receptors in the trigone area but not in the rest of the bladder. In view of the patient's mildly raised estrogen levels and the histological findings, we postulate that estrogen is the driver of the development of pseudomembranous trigonitis. This is the first reported case of pseudomembranous trigonitis seen in association with Klinefelter syndrome, and also the first case of pseudomembranous trigonitis occurring within the male adolescent age group.

  11. Rotational Symmetry Breaking in a Trigonal Superconductor Nb-doped Bi_{2}Se_{3}

    Directory of Open Access Journals (Sweden)

    Tomoya Asaba

    2017-01-01

    Full Text Available The search for unconventional superconductivity has been focused on materials with strong spin-orbit coupling and unique crystal lattices. Doped bismuth selenide (Bi_{2}Se_{3} is a strong candidate, given the topological insulator nature of the parent compound and its triangular lattice. The coupling between the physical properties in the superconducting state and its underlying crystal symmetry is a crucial test for unconventional superconductivity. In this paper, we report direct evidence that the superconducting magnetic response couples strongly to the underlying trigonal crystal symmetry in the recently discovered superconductor with trigonal crystal structure, niobium (Nb-doped Bi_{2}Se_{3}. As a result, the in-plane magnetic torque signal vanishes every 60°. More importantly, the superconducting hysteresis loop amplitude is enhanced along one preferred direction, spontaneously breaking the rotational symmetry. This observation indicates the presence of nematic order in the superconducting ground state of Nb-doped Bi_{2}Se_{3}.

  12. Synthesis and Reactivity of Metal Complexes in Trigonal N,O,O,O-Environments

    OpenAIRE

    Adelhardt, Mario Erwin

    2016-01-01

    High-valent iron complexes, for instance stabilized by multiple bonded oxo, nitrido, or imido ligands, have been identified as reactive intermediates in biological as well as technical systems. Although numerous synthetic model complexes have been synthesized and characterized in the past four decades, they often lack the high reactivity of their parental compounds. One strategy to enhance the reactivity of, for example, Fe(IV) oxo complexes is to enforce a trigonal coordination geometry ar...

  13. Magnetic anisotropy of a Co-II single ion magnet with distorted trigonal prismatic coordination

    DEFF Research Database (Denmark)

    Peng, Yan; Bodenstein, Tilmann; Fink, Karin

    2016-01-01

    The single ion magnetic properties of Co(II) are affected by the details of the coordination geometry of the ion. Here we show that a geometry close to trigonal prismatic which arises when the ligand 6,6'-((1Z)-((piperazine-1,4-diylbis(propane-3,1-diyl)) bis(azanylylidene)) bis(methanylylidene)) ......The single ion magnetic properties of Co(II) are affected by the details of the coordination geometry of the ion. Here we show that a geometry close to trigonal prismatic which arises when the ligand 6,6'-((1Z)-((piperazine-1,4-diylbis(propane-3,1-diyl)) bis(azanylylidene)) bis......(methanylylidene)) bis(2-methoxyphenol) coordinates to Co(II) does indeed lead to enhanced single-ion behaviour as has previously been predicted. Synthesis of the compound, structural information, and static as well as dynamic magnetic data are presented along with an analysis using quantum chemical ab initio...... calculations. Though the complex shows a slight deviation from an ideal trigonal prismatic coordination, the zero-field splitting as well as the g-tensor are strongly axial with D = -41 cm(-1) and E

  14. Assembly of silver Trigons into a buckyball-like Ag180nanocage.

    Science.gov (United States)

    Wang, Zhi; Su, Hai-Feng; Tan, Yuan-Zhi; Schein, Stan; Lin, Shui-Chao; Liu, Wei; Wang, Shu-Ao; Wang, Wen-Guang; Tung, Chen-Ho; Sun, Di; Zheng, Lan-Sun

    2017-11-14

    Buckminsterfullerene (C 60 ) represents a perfect combination of geometry and molecular structural chemistry. It has inspired many creative ideas for building fullerene-like nanopolyhedra. These include other fullerenes, virus capsids, polyhedra based on DNA, and synthetic polynuclear metal clusters and cages. Indeed, the regular organization of large numbers of metal atoms into one highly complex structure remains one of the foremost challenges in supramolecular chemistry. Here we describe the design, synthesis, and characterization of a Ag 180 nanocage with 180 Ag atoms as 4-valent vertices (V), 360 edges (E), and 182 faces (F)--sixty 3-gons, ninety 4-gons, twelve 5-gons, and twenty 6-gons--in agreement with Euler's rule V - E + F = 2. If each 3-gon (or silver Trigon) were replaced with a carbon atom linked by edges along the 4-gons, the result would be like C 60 , topologically a truncated icosahedron, an Archimedean solid with icosahedral ( I h ) point-group symmetry. If C 60 can be described mathematically as a curling up of a 6.6.6 Platonic tiling, the Ag 180 cage can be described as a curling up of a 3.4.6.4 Archimedean tiling. High-resolution electrospray ionization mass spectrometry reveals that {Ag 3 } n subunits coexist with the Ag 180 species in the assembly system before the final crystallization of Ag 180 , suggesting that the silver Trigon is the smallest building block in assembly of the final cage. Thus, we assign the underlying growth mechanism of Ag 180 to the Silver-Trigon Assembly Road (STAR), an assembly path that might be further employed to fabricate larger, elegant silver cages.

  15. Variational method of determining effective moduli of polycrystals: (A) hexagonal symmetry, (B) trigonal symmetry

    Science.gov (United States)

    Peselnick, L.; Meister, R.

    1965-01-01

    Variational principles of anisotropic elasticity have been applied to aggregates of randomly oriented pure-phase polycrystals having hexagonal symmetry and trigonal symmetry. The bounds of the effective elastic moduli obtained in this way show a considerable improvement over the bounds obtained by means of the Voigt and Reuss assumptions. The Hill average is found to be in most cases a good approximation when compared to the bounds found from the variational method. The new bounds reduce in their limits to the Voigt and Reuss values. ?? 1965 The American Institute of Physics.

  16. The Cohen cross-trigonal technic for vesicoureteral reflux with contracted bladder in children

    OpenAIRE

    進藤, 和彦; 野俣, 浩一郎; 城代, 明仁; 実藤, 健; 金武, 洋; 斉藤, 泰; 計屋, 紘信; 由良, 守司; 松崎, 幸康

    1984-01-01

    A 8-year-old girl was referred with both vesicoureteral reflux and repeated urinary infection since she was 30 months old. At 5 years old, she had had cystoscopy. Her excretory urogram (IVP) was almost normal; her voiding cystogram showed both vesicoureteral reflux of grade III and a maximum bladder capacity of 75 ml. At cystoscopy the ureteral orifices were in normal position of the trigone and the orifices were dilated like a golf-hole. Both ureters were reimplanted without ureter stents by...

  17. Calculation of the phonon density of states and related thermodynamic properties for trigonal selenium

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Alldredge, G. P.; McMurry, H. L.

    1983-01-01

    The phonon density of states for trigonal selenium has been calculated on the basis of a short range force model giving good overall agreement with experimental room temperature phonon dispersion data. A qualitative comparison with an experimental determination of the phonon density of states shows...... similarities in the gross features, but the experimental data lacks many of the finer details shown by the theoretical results due to resolution effects. The lattice dynamical contribution to the heat capacity CV is calculated and is found to be in good agreement with experimental determinations of Cp after...... transforming Cp to CV. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

  18. Distribution and chemical coding of neurons in intramural ganglia of the porcine urinary bladder trigone.

    Directory of Open Access Journals (Sweden)

    Zenon Pidsudko

    2004-03-01

    Full Text Available This study presents the distribution and chemical coding of neurons in the porcine intramural ganglia of the urinary bladder trigone (IG-UBT demonstrated using combined retrograde tracing and double-labelling immunohistochemistry. Retrograde fluorescent tracer Fast Blue (FB was injected into the wall of both the left and right side of the bladder trigone during laparotomy performed under pentobarbital anaesthesia. Ten-microm-thick cryostat sections were processed for double-labelling immunofluorescence with antibodies against tyrosine hydroxylase (TH, dopamine beta-hydroxylase (DBH, neuropeptide Y (NPY, somatostatin (SOM, galanin (GAL, vasoactive intestinal polypeptide (VIP, nitric oxide synthase (NOS, calcitonin gene-related peptide (CGRP, substance P (SP, Leu5-enkephalin (LENK and choline acetyltransferase (ChAT. IG-UBT neurons formed characteristic clusters (from a few to tens neuronal cells found under visceral peritoneum or in the outer muscular layer. Immunohistochemistry revealed four main populations of IG-UBT neurons: SOM- (ca. 35%, SP- (ca. 32%, ChAT- and NPY- immunoreactive (-IR (ca. 23% as well as non-adrenergic non-cholinergic nerve cells (ca. 6%. This study has demonstrated a relatively large population of differently coded IG-UBT neurons, which constitute an important element of the complex neuro-endocrine system involved in the regulation of the porcine urogenital organ function.

  19. Modeling the radiation ionization energy and energy resolution of trigonal and amorphous selenium from first principles.

    Science.gov (United States)

    Darbandi, A; Devoie, É; Di Matteo, O; Rubel, O

    2012-11-14

    Advances in the development of amorphous selenium-based direct conversion photoconductors for high-energy radiation critically depend on the improvement of its sensitivity to ionizing radiation, which is directly related to the pair production energy. Traditionally, theories for the pair production energy have been based on the parabolic band approximation and do not provide a satisfactory agreement with experimental results for amorphous selenium. Here we present a calculation of the pair creation energy in trigonal and amorphous selenium based on its electronic structure. In indirect semiconductors, such as trigonal selenium, the ionization threshold energy can be as low as the energy gap, resulting in a lower pair creation energy, which is a favorable factor for sensitivity. Also, the statistics of photogenerated charge carriers is studied in order to evaluate the theoretical value of the Fano factor and its dependence on recombination processes. We show that recombination can significantly compromise the detector's energy resolution as a result of an increase in the Fano factor.

  20. Theoretical investigations of zero-field splitting of excited states for 3d3 ions in trigonal crystal fields.

    Science.gov (United States)

    Wei, Qun; Yang, Ziyuan; Wang, Canjun; Xu, Qiming

    2007-11-01

    By taking into account slight interactions, i.e. spin-spin, spin-other-orbit and orbit-orbit interactions, in addition to spin-orbit interaction, the zero-field splitting of ground state and low excited states and g factors of ZnGa2O4:Cr3+ crystal have been interpreted systematically. And the contributions to zero-field splitting arising from slight magnetic interaction and trigonal crystal field are investigated. It is found that there exist combined mechanism between magnetic interactions and trigonal crystal field.

  1. Spin tunnelling of trigonal and hexagonal ferromagnets in an arbitrarily directed magnetic field

    Science.gov (United States)

    Lü, Rong; Zhu, Jia-Lin; Liu, Zhi-Rong; Chang, Lee; Gu, Bing-Lin

    2000-05-01

    The quantum tunnellings of the magnetization vector in single-domain ferromagnetic nanoparticles placed in an external magnetic field at an arbitrarily directed angle in the ZX-plane are studied theoretically. We consider magnetocrystalline anisotropies with trigonal and hexagonal crystal symmetry. By applying the instanton technique in the spin-coherent-state path-integral representation, we calculate the tunnel splittings, the tunnelling rates, and the crossover temperatures in the low-barrier limit for different angle ranges of the external magnetic field (θH = π/2, π/2crossover temperatures depend distinctly on the orientation of the external magnetic field, which provides a possible experimental test for magnetic quantum tunnelling in nanometre-scale single-domain ferromagnets.

  2. ZnO/CoO and ZnCo2O4 Hierarchical Bipyramid Nanoframes: Morphology Control, Formation Mechanism, and Their Lithium Storage Properties.

    Science.gov (United States)

    Bai, Jing; Wang, Kaiqi; Feng, Jinkui; Xiong, Shenglin

    2015-10-21

    Mastery over the structure of nanoscale materials can effectively tailor and regulate their electrochemical properties, enabling improvement in both rate capability and cycling stability. We report the shape-controlled synthesis of novel mesoporous bicomponent-active ZnO/CoO hierarchical multilayered bipyramid nanoframes (HMBNFs). The as-synthesized micro/nanocrystals look like multilayered bipyramids and consist of a series of structural units with similar frames and uniform sheet branches. The use of an appropriate straight-chain monoalcohol was observed to be critical for the formation of HMBNFs. In addition, the structure of HMBNFs could be preserved only in a limited range of the precursor ratio. An extremely fast crystal growth process and an unusual transverse crystallization of the ZnCo-carbonate HMBNFs were newly discovered and proposed. By calcination of ZnCo-carbonate HMBNFs at the atmosphere of nitrogen and air, ZnO/CoO and ZnCo2O4 HMBNFs were obtained, respectively. Compared to the ZnCo2O4 HMBNFs, the ZnO/CoO HMBNFs with a uniform distribution of nanocrystal ZnO and CoO subunits exhibited enhanced electrochemical activity, including greater rate capability and longer cycling performance, when evaluated as an anode material for Li-ion batteries. The superior electrochemical performance of the ZnO/CoO HMBNFs is attributed to the unique nanostructure, bicomponent active synergy, and uniform distribution of ZnO and CoO phases at the nanoscale.

  3. Ultrasensitive electrochemical detection of microRNA with star trigon structure and endonuclease mediated signal amplification.

    Science.gov (United States)

    Miao, Peng; Wang, Bidou; Yu, Zhiqiang; Zhao, Jing; Tang, Yuguo

    2015-01-15

    MicroRNAs play important roles in gene regulation. They can be used as effective biomarkers for diagnosis and prognosis of diseases like cancers. Due to their intrinsic properties of short length, low abundance and sequence homology among family members, it is difficult to realize sensitive and selective detection with economical use of time and cost. Herein, we report an ultrasensitive electrochemical method for microRNA analysis employing two oligonucleotides and one endonuclease. Generally, a glassy carbon electrode is first covered with gold nanoparticles (AuNPs) mediated by poly(diallyldimethylammonium chloride) (PDDA). Then, thiolated capture probe (CP) with methylene blue (MB) labeled at 5' end is modified on the pretreated electrode. Hybridization occurs among target microRNA, CP and auxiliary probe (AP), forming a star trigon structure on the electrode surface. Subsequently, endonuclease recognizes and cleaves CP on CP/AP duplex, releasing microRNA and AP back to the solution. The two regenerated elements can then form another star trigon with other CP molecules, initiating cycles of CP cleavage and MB departure. Significant decrease of electrochemical signals is thus observed, which can be used to reflect the concentration of microRNA. This proposed method has a linear response to microRNA in a wide range from 100 aM to 1 nM and the sensitivity of attomolar level can be achieved. Moreover, it has high selectivity against single-base mismatch sequences and can be used directly in serum samples. Therefore, this method shows great feasibility for the detection of microRNA and may have potential applications in cancer diagnosis and prognosis. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. The asc trinodal platform: Two-step assembly of triangular, tetrahedral, and trigonal-prismatic molecular building blocks

    KAUST Repository

    Schoedel, Alexander

    2013-02-10

    The self-assembly of triangular, tetrahedral, and trigonal-prismatic molecular building blocks affords the first example of a trinodal family of metal-organic materials. Four examples of isoreticular expanded and functionalized frameworks are detailed. Gas adsorption experiments validated the permanent porosity of the parent structure. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Nonlinear Elastic Behavior of Piezoelectric Trigonal Crystals: Measurements on Quartz and Lithium-Niobate

    Science.gov (United States)

    Latimer, Paul Jerry

    The ultrasonic harmonic generation technique previously used to measure third-order elastic (TOE) constants of crystals of cubic symmetry has been extended to measurement of crystals of trigonal symmetry. The theory for nonpiezoelectric trigonal crystals of J. Philip {Technical Report No. 22, Office of Naval Research, Contract No. N00014 -81-K-0229 (to be published in 1983)} has been combined with the piezoelectric theory of McMahon {J. Acoust. Soc. Am. 44, 1007 (1968)} to determine the effective TOE constants in a piezoelectric solid, and correction has been made in McMahon's expression. Measurements in weakly piezoelectric quartz have produced values of C(,111) and C(,333) which agree within experimental uncertainty with values of R. N. Thurston, H. J. McSkimin and P. Andreatch, Jr. {J. Appl. Phys. 37, 267 (1966)} and R. Stern and R. T. Smith {J. Acoust. Soc. Am. 44, 640 (1968)} after corrections have been made for the effect of diffraction on the data. Measurements in strongly piezoelectric LiNbO(,3) have resulted in values which agree reasonably well with those of J. Philip and M. A. Breazeale {Proc. IEEE Ultrasonics Symposium, Vol. 2 (1982) } but disagree with those of C. Y. Nakagawa, K. Yamanouchi and K. Shibayama {J. Appl. Phys. 44, 3969 (1973) }. There is indication of some sample dependence of the values of both the second-order elastic constants as well as the third-order elastic constants of LiNbO(,3) samples currently available. In the course of measurement of the TOE constants a negative nonlinearity parameter was observed for the Piezoelectric {100} direction in quartz. This peculiarity is impossible for thermodynamic reasons in fluids, but has been observed once previously in fused silica {J. Bains and M. A. Breazeale, J. Acoust, Soc. Am. 57, 745 (1975)}. The nonlinearity parameter appears to be positive for the piezoelectric {001 } direction in LiNbO(,3). The data presented are for the "piezoelectrically stiffened" TOE constants; however, there are

  6. The First Homoleptic Complex of Seven-Coordinated Osmium: Synthesis and Crystallographical Evidence of Pentagonal Bipyramidal Polyhedron of Heptacyanoosmate(IV

    Directory of Open Access Journals (Sweden)

    Eugenia V. Peresypkina

    2016-08-01

    Full Text Available The ligand exchange in (n-Bu4N2OsIVCl6 (n-Bu4N = tetra-n-butylammonium leads to the formation of the osmium(IV heptacyanide, the first fully inorganic homoleptic complex of heptacoordinated osmium. The single-crystal X-ray diffraction (SC-XRD study reveals the pentagonal bipyramidal molecular structure of the [Os(CN7]3− anion. The latter being a diamagnetic analogue of the highly anisotropic paramagnetic synthon, [ReIV(CN7]3− can be used for the synthesis of the model heterometallic coordination compounds for the detailed study and simulation of the magnetic properties of the low-dimensional molecular nanomagnets involving 5d metal heptacyanides.

  7. One-pot synthesis of oxamidato-bridged hexarhenium trigonal prisms adorned with ester functionality.

    Science.gov (United States)

    Nagarajaprakash, R; Govindarajan, R; Manimaran, Bala

    2015-07-14

    Oxamidato-bridged Re(I)-based hexanuclear trigonal prisms with ester functionality have been synthesised via a multicomponent self-assembly process under solvothermal conditions. The self-assembly of Re2(CO)10, oxamide ligands (H2L1 = N,N′-dibutyloxamide, H2L2 = N,N′-dioctyloxamide, H2L3 = N,N′-didodecyloxamide and H2L4 = N,N′-dibenzyloxamide) and phenyl-1,3,5-tris(isonicotinate) (ptin) resulted in the formation of metallaprisms with the general formula [{(CO)3Re(μ–η(4)-L)Re(CO)3}3(μ3-ptin)2] (1–4). The metallaprisms 1–4 have been characterised using spectroscopic techniques, and the molecular structure of 4 has been elucidated by single-crystal X-ray diffraction methods. Investigations on the guest binding ability of 2 with a few aromatic alcohols and L-tryptophan using UV–vis and fluorescence spectroscopic titration experiments revealed strong host–guest interactions. The luminescence enhancement studies of 2 and 3 have been carried out using organic-aqueous solvent mixtures.

  8. Neutron transport in hexagonal reactor cores modeled by trigonal-geometry diffusion and simplified P{sub 3} nodal methods

    Energy Technology Data Exchange (ETDEWEB)

    Duerigen, Susan

    2013-05-15

    The superior advantage of a nodal method for reactor cores with hexagonal fuel assemblies discretized as cells consisting of equilateral triangles is its mesh refinement capability. In this thesis, a diffusion and a simplified P{sub 3} (or SP{sub 3}) neutron transport nodal method are developed based on trigonal geometry. Both models are implemented in the reactor dynamics code DYN3D. As yet, no other well-established nodal core analysis code comprises an SP{sub 3} transport theory model based on trigonal meshes. The development of two methods based on different neutron transport approximations but using identical underlying spatial trigonal discretization allows a profound comparative analysis of both methods with regard to their mathematical derivations, nodal expansion approaches, solution procedures, and their physical performance. The developed nodal approaches can be regarded as a hybrid NEM/AFEN form. They are based on the transverse-integration procedure, which renders them computationally efficient, and they use a combination of polynomial and exponential functions to represent the neutron flux moments of the SP{sub 3} and diffusion equations, which guarantees high accuracy. The SP{sub 3} equations are derived in within-group form thus being of diffusion type. On this basis, the conventional diffusion solver structure can be retained also for the solution of the SP{sub 3} transport problem. The verification analysis provides proof of the methodological reliability of both trigonal DYN3D models. By means of diverse hexagonal academic benchmark and realistic detailed-geometry full-transport-theory problems, the superiority of the SP{sub 3} transport over the diffusion model is demonstrated in cases with pronounced anisotropy effects, which is, e.g., highly relevant to the modeling of fuel assemblies comprising absorber material.

  9. Clarification of the Hashin-Shtrikman bounds on the effective elastic moduli of polycrystals with hexagonal, trigonal, and tetragonal symmetries

    Science.gov (United States)

    Watt, J.P.; Peselnick, L.

    1980-01-01

    Bounds on the effective elastic moduli of randomly oriented aggregates of hexagonal, trigonal, and tetragonal crystals are derived using the variational principles of Hashin and Shtrikman. The bounds are considerably narrower than the widely used Voigt and Reuss bounds. The Voigt-Reuss-Hill average lies within the Hashin-Shtrikman bounds in nearly all cases. Previous bounds of Peselnick and Meister are shown to be special cases of the present results.

  10. Pseudomembranous trigonitis in a male with Klinefelter syndrome: a case report and evidence of a hormonal etiology

    OpenAIRE

    Lian, Derrick WQ; Li, Fay X; Ong, Caroline CP; Kuick, CH; Chang, Kenneth TE

    2014-01-01

    Klinefelter syndrome is a clinical syndrome with a distinct 47, XXY karyotype. Patients are characterized by a tall eunuchoid stature, small testes, hypergonotrophic hypogonadism, gynecomastia, learning difficulties and infertility. These patients have also been found to have raised estrogen levels. We report a 16 year old boy with Klinefelter syndrome presenting to our institution with gross hematuria. Cystoscopy and biopsy revealed the diagnosis of pseudomembranous trigonitis. Immunohistoch...

  11. Network diversity through decoration of trigonal-prismatic nodes: Two-step crystal engineering of cationic metal-organic materials

    KAUST Repository

    Schoedel, Alexander

    2011-10-05

    MOMs the word! In a two-step process, first a trigonal-prismatic Primary Molecular Building Block ([Cr3O(isonic)6]+, tp-PMBB-1) was formed and then it was connected to linear linkers or square-planar nodes to afford three novel highly charged cationic metal-organic materials (MOMs) with snx, snw, and stp topologies. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Syntheses, structures and physical properties of transition metal-organic frameworks assembled from trigonal heterofunctional ligands.

    Science.gov (United States)

    Song, Shu-Yan; Song, Xue-Zhi; Zhao, Shu-Na; Qin, Chao; Su, Sheng-Qun; Zhu, Min; Hao, Zhao-Min; Zhang, Hong-Jie

    2012-09-14

    Six novel metal-organic frameworks (MOFs), {Mn(bpydb)(bpyHdbH)}(n) (1) {[Co(2)(bpydb)(2)](H(2)O)(0.5)}(n) (2), {[Ni(0.5)(bpydbH)(H(2)O)](DMF)(2)}(n) (3), {[Cu(2)(bpydb)(2)](H(2)O)(0.5)}(n) (4), {Zn(bpyHdb)(2)}(n) (5) and {[Cd(0.5)(bpydb)(0.5)(DMF)](H(2)O)}(n) (6), were successfully synthesized by assembling transition metal salts with trigonal heterofunctional ligand 4,4'-(4,4'-bipyridine-2,6-diyl) dibenzoic acid (bpydbH(2)) under hydrothermal and/or solvothermal conditions. Compound 1 features a rare 4-fold interpenetrating (3,5)-connected framework with hms-type topology. Isostructural compounds 2 and 4, constructed by M(2)(COO)(4) secondary building units, exhibit a robust 3D framework with alb topological type in 2-fold interpenetrating mode. Compound 3 consists of 2D (4,4) networks, which are further assembled into the new topological framework with the symbol (5(3)·6(2)·8)(5(3)·6(3))(2) through O-HO interactions. Compound 5 manifests a novel 4-connected interpenetrating framework, constructed by 2D (4,4) layers and interbedded N-HO interactions. Non-interpenetrating honeycomb networks are observed in compound 6, and further packed into a 3D framework featuring 1D channels. The magnetic susceptibility of compound 2 indicates antiferromagnetic interactions between cobalt ions. The photoluminescent properties of 5 and 6 were investigated in the solid state at room temperature.

  13. Chemically exfoliated Mo S2 layers: Spectroscopic evidence for the semiconducting nature of the dominant trigonal metastable phase

    Science.gov (United States)

    Pal, Banabir; Singh, Anjali; Sharada, G.; Mahale, Pratibha; Kumar, Abhinav; Thirupathaiah, S.; Sezen, H.; Amati, M.; Gregoratti, Luca; Waghmare, Umesh V.; Sarma, D. D.

    2017-11-01

    A metastable trigonal phase, existing only as small patches on a chemically exfoliated few-layered, thermodynamically stable 1 H phase of Mo S2 , is believed to critically influence the properties of Mo S2 -based devices. The electronic structure of this metastable phase is little understood in the absence of a direct experimental investigation of its electronic properties, complicated further by conflicting claims from theoretical investigations. We address this issue by investigating the electronic structure of this minority phase in chemically exfoliated Mo S2 few-layered systems by enhancing its contributions with the use of highly spatially resolved (≤120 nm resolution) photoemission spectroscopy and Raman spectroscopy in conjunction with state-of-the-art electronic structure calculations. Based on these results, we establish that the ground state of this phase, arrived at by the chemical exfoliation of Mo S2 using the usual Li intercalation technique, is a small gap (˜90 ±40 meV ) semiconductor in contrast to most claims in the literature; we also identify the specific trigonal structure it has among many suggested ones.

  14. Modulation of luminescence by subtle anion-cation and anion-π interactions in a trigonal Au(I)···Cu(I) complex.

    Science.gov (United States)

    Chen, Kelly; Strasser, Christoph E; Schmitt, Jennifer C; Shearer, Jason; Catalano, Vincent J

    2012-02-06

    The trigonally coordinated [AuCu(PPh(2)py)(3)](BF(4))(2) (1) crystallizes in two polymorphs and a pseudopolymorph, each of which contains a trigonally coordinated cation with short Au(I)-Cu(I) separations of ∼2.7 Å. Under UV illumination, these crystals luminesce different colors ranging from blue to yellow. The structures of these cations are nearly superimposable, and the primary difference resides in the relative placement of the anions and solvate molecules. As confirmed by time-dependent density functional theory calculations, it is these interactions that are responsible for the differential emission properties.

  15. Impact of Dose to the Bladder Trigone on Long-Term Urinary Function After High-Dose Intensity Modulated Radiation Therapy for Localized Prostate Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Ghadjar, Pirus; Zelefsky, Michael J.; Spratt, Daniel E. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Munck af Rosenschöld, Per; Oh, Jung Hun; Hunt, Margie [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Kollmeier, Marisa [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Happersett, Laura; Yorke, Ellen; Deasy, Joseph O. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Jackson, Andrew, E-mail: jacksona@mskcc.org [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

    2014-02-01

    Purpose: To determine the potential association between genitourinary (GU) toxicity and planning dose–volume parameters for GU pelvic structures after high-dose intensity modulated radiation therapy in localized prostate cancer patients. Methods and Materials: A total of 268 patients who underwent intensity modulated radiation therapy to a prescribed dose of 86.4 Gy in 48 fractions during June 2004-December 2008 were evaluated with the International Prostate Symptom Score (IPSS) questionnaire. Dose–volume histograms of the whole bladder, bladder wall, urethra, and bladder trigone were analyzed. The primary endpoint for GU toxicity was an IPSS sum increase ≥10 points over baseline. Univariate and multivariate analyses were done by the Kaplan-Meier method and Cox proportional hazard models, respectively. Results: Median follow-up was 5 years (range, 3-7.7 years). Thirty-nine patients experienced an IPSS sum increase ≥10 during follow-up; 84% remained event free at 5 years. After univariate analysis, lower baseline IPSS sum (P=.006), the V90 of the trigone (P=.006), and the maximal dose to the trigone (P=.003) were significantly associated with an IPSS sum increase ≥10. After multivariate analysis, lower baseline IPSS sum (P=.009) and increased maximal dose to the trigone (P=.005) remained significantly associated. Seventy-two patients had both a lower baseline IPSS sum and a higher maximal dose to the trigone and were defined as high risk, and 68 patients had both a higher baseline IPSS sum and a lower maximal dose to the trigone and were defined as low risk for development of an IPSS sum increase ≥10. Twenty-one of 72 high-risk patients (29%) and 5 of 68 low-risk patients (7%) experienced an IPSS sum increase ≥10 (P=.001; odds ratio 5.19). Conclusions: The application of hot spots to the bladder trigone was significantly associated with relevant changes in IPSS during follow-up. Reduction of radiation dose to the lower bladder and specifically the

  16. Investigation of Self-Assembly of Two-Component Organogel System Based on Trigonal Acids and Aminobenzothiazole Derivatives

    Directory of Open Access Journals (Sweden)

    Youbo Di

    2013-01-01

    Full Text Available We reported here the gelation behaviors of two-component organogel system based on different acids and aminobenzothiazole derivatives in various organic solvents. Their gelation behaviors in 20 solvents were tested as new organic gelators. It was shown that the molecular skeletons and substituted groups in these compounds played a crucial role in the gelation behavior of the mixtures. Only the binary mixture of 2-aminobenzothiazole and trigonal 1,3,5-benzenetricarboxylic acid with aromatic core could form organogels in ethanol and acetone. Morphological observations reveal that the microstructures of both xerogels showed similar wrinkle-shaped domains composed of sheet-like aggregates with many holes. Spectral studies reveal the hydrogen bonding interaction between the amide of the gelator and lamellar-like structure of the aggregates in both gels. The present investigation is a perspective to provide new clues for the design of new nanomaterials and functional textile materials with special microstructures.

  17. 4,6-connected fsb topology networks obtained through two-step crystal engineering of decorated trigonal prismatic nodes

    KAUST Repository

    Schoedel, Alexander

    2014-05-07

    A two-step crystal engineering strategy has been utilized to synthesize a new and versatile class of metal-organic materials, the first to exhibit 4,6-connected fsb topology. The new fsb networks are constructed from simple and inexpensive nodes (4-connected Zn(CO2)(py)2 tetrahedra; 6-connected Cr(μ3-O)(RCO2)6 trigonal prisms) and linker ligands (isonicotinate and various dicarboxylates). Further, since interpenetration is precluded, they can exhibit extra-large void volumes. These fsb nets are prototypal for what should ultimately become a large family of related structures given the ready availability of functionalized and/or expanded variants of both linker ligands. The fsb nets described herein therefore represent platforms or blueprints for a new family of ultrahigh surface area porous materials. © 2014 American Chemical Society.

  18. Total cystectomy for treatment of transitional cell carcinoma of the urethra and bladder trigone in a dog.

    Science.gov (United States)

    Boston, Sarah; Singh, Ameet

    2014-03-01

    To report total cystectomy with reimplantation of the ureters in the proximal aspect of the vagina. Case report. An 11-year-old female spayed Vizsla with spontaneously occurring transitional cell carcinoma of the urethra and bladder. After initial treatment for transitional cell carcinoma of the bladder trigone with urethral stent placement and chemotherapy, the dog developed urinary incontinence 2 months after stent placement. Eleven months after initial diagnosis, the dog developed pulmonary metastasis and local progression, leading to bilateral ureteral dilatation. After palliative radiation, total cystectomy was performed. The owners elected euthanasia 442 days after original presentation and 92 days after total cystectomy. Euthanasia was unrelated to the surgical procedure, but was related to the primary disease. Total cystectomy is a technically feasible procedure that should be considered for the treatment of bladder cancer in dogs. © Copyright 2014 by The American College of Veterinary Surgeons.

  19. Radical Cystectomy and Cutaneous Ureterostomy in 4 Dogs with Trigonal Transitional Cell Carcinoma: Description of Technique and Case Series.

    Science.gov (United States)

    Ricardo Huppes, Rafael; Crivellenti, Leandro Z; Barboza De Nardi, Andrigo; Roque Lima, Bruno; Alves Cintra, Cristiane; Luiz Costa Castro, Jorge; Adin, Christopher A

    2017-01-01

    To describe radical cystectomy followed by cutaneous ureterostomy as a treatment of invasive bladder neoplasia in dogs. Retrospective study. Client-owned dogs with transitional cell carcinoma of the bladder trigone (n=4). Perioperative complications and long-term outcomes of dogs that underwent cutaneous ureterostomy following radical cystectomy and lymphadenectomy for transitional cell carcinoma of the urinary bladder trigone were reviewed. Both ureters were transected and anastomosed to the ventral abdominal skin. Polyvinyl chloride catheters were placed in the ureteral stomas and maintained for 5 days. After catheter removal, dogs were managed with an absorbent diaper over the stomas. Long-term outcome and survival were documented by follow-up visits or phone contact. Median age at the time of surgery was 10.3 years (range, 8-12). Average procedural time was ∼4.7 hours (range, 3.8-6.1). Minor complications occurred in all dogs, including bleeding and edema of the ureterostomy site during the first 2-3 days after surgery. One dog developed urine scald that resolved with improved stoma care and hygiene. Median survival time after surgery was 278.6 days (range, 47-498). Distant metastases were documented in 2 dogs at 47 days (bone) and 369 days (lung) after surgery. Radical cystectomy with cutaneous ureterostomy is a viable salvage procedure for urinary diversion after cystectomy in dogs with invasive bladder neoplasia. Postoperative management and quality of life were considered acceptable by most owners. Future studies are warranted to evaluate survival time in a larger number of animals. © 2016 The American College of Veterinary Surgeons.

  20. Evaluation of sinking-in and cracking behavior of soda-lime glass under varying angle of trigonal pyramid indenter

    Directory of Open Access Journals (Sweden)

    Satoshi Yoshida

    2016-12-01

    Full Text Available It is well known that glass undergoes elastic and inelastic deformation under a sharp diamond indenter. Although brittle or less-brittle behavior of glass must be connected with such mechanical responses of glass under the indenter, there has been limited research on in-situ deformation behavior of glass during the loading and unloading indentation cycle. This is because most indentation tests were conducted using a commercial hardness tester for which this information is not available. In this study, the in-situ sinking-in region of glass during indentation test is determined using a custom-designed indentation microscope with trigonal pyramid indenters having different tip angles. It is found that both the shape of contact region and the amount of sinking-in are affected by indenter geometries, and that the projected contact region of the glass sample under Berkovich indenter is not a regular triangle, but a concave triangle with bowed-in edges. This is due to the larger amount of sinking-in under the face than under the ridge of indenter. It is also found that these deformation behaviors of glass are inseparably linked with contact damage or cracking in glass.

  1. Ferroquadrupolar Ordering due to the Quasi-degenerate Quartet in the Trigonal Chiral Structure of DyNi3Ga9

    Science.gov (United States)

    Ishii, Isao; Takezawa, Kohki; Mizuno, Takuyou; Kamikawa, Shuhei; Ninomiya, Hiroki; Matsumoto, Yuji; Ohara, Shigeo; Mitsumoto, Keisuke; Suzuki, Takashi

    2018-01-01

    To clarify the origin of the phase transition at TN = 10 K in the trigonal chiral compound DyNi3Ga9, we performed ultrasonic measurements on single-crystalline samples. We found a significant elastic softening of the transverse modulus C66 toward TN. By analyzing the data using the strain susceptibility, the positive sign of the quadrupole-quadrupole coupling constant for C66 was obtained. These results strongly suggest that ferroquadrupolar ordering will be dominant for the phase transition at TN. Below TN, crystal symmetry will lower from the trigonal structure. Elastic softening below TN occurs in the other elastic moduli, reflecting that some kind of instability is still alive below TN. Elastic anomalies detected below TN suggest successive phase transitions.

  2. Highly porous and robust ionic MOFs with nia topology constructed by connecting an octahedral ligand and a trigonal prismatic metal cluster.

    Science.gov (United States)

    Jia, Jiangtao; Sun, Fuxing; Borjigin, Tsolmon; Ren, Hao; Zhang, Tingting; Bian, Zheng; Gao, Lianxun; Zhu, Guangshan

    2012-06-18

    Two non-interpenetrated and isomorphous MOFs with nia topology, cationic JUC-101 and anionic JUC-102, are synthesized by connecting a trigonal prismatic metal cluster with an octahedral organic ligand. JUC-101 obtains a BET surface area of 3742 m(2) g(-1) and can absorb 4.18 wt% of H2 at 30 atm and 77 K, while JUC-102 can absorb cationic dye molecules and release them under the triggering of ions.

  3. Suggestive Evidence for the Involvement of the Second Calcium and Surface Loop in Interfacial Binding: Monoclinci and Trigonal Crystal Structures of a Quadruple Mutant of Phospholipase A2

    Energy Technology Data Exchange (ETDEWEB)

    Sekar,K.; Yogavel, M.; Kanaujia, S.; Sharma, A.; Velmurugan, D.; Poi, M.; Dauter, Z.; Tsai, M.

    2006-01-01

    The crystal structures of the monoclinic and trigonal forms of the quadruple mutant K53,56,120,121M of recombinant bovine pancreatic phospholipase A{sub 2} (PLA{sub 2}) have been solved and refined at 1.9 and 1.1 Angstroms resolution, respectively. Interestingly, the monoclinic form reveals the presence of the second calcium ion. Furthermore, the surface-loop residues are ordered and the conformation of residues 62-66 is similar to that observed in other structures containing the second calcium ion. On the other hand, in the trigonal form the surface loop is disordered and the second calcium is absent. Docking studies suggest that the second calcium and residues Lys62 and Asp66 from the surface loop could be involved in the interaction with the polar head group of the membrane phospholipid. It is hypothesized that the two structures of the quadruple mutant, monoclinic and trigonal, represent the conformations of PLA2 at the lipid interface and in solution, respectively. A docked structure with a phospholipid molecule and with a transition-state analogue bound, one at the active site coordinating to the catalytic calcium and the other at the second calcium site, but both at the i-face, is presented.

  4. Synthesis, characterization and crystal structures of two pentagonal-bipyramidal Fe(III) complexes with dihydrazone of 2,6-diacetylpyridine and Girard's T reagent. Anticancer properties of various metal complexes of the same ligand.

    Science.gov (United States)

    Anđelković, Katarina; Milenković, Milica R; Pevec, Andrej; Turel, Iztok; Matić, Ivana Z; Vujčić, Miroslava; Sladić, Dušan; Radanović, Dušanka; Brađan, Gabrijela; Belošević, Svetlana; Čobeljić, Božidar

    2017-09-01

    In this work synthesis, characterization and crystal structures of two isothiocyanato Fe(III) complexes with 2,2'-[2,6-pyridinediylbis(ethylidyne-1-hydrazinyl-2-ylidene)]bis[N,N,N-trimethyl-2-oxoethanaminium] dichloride (H2LCl2) ligand, with composition [FeL(NCS)2]SCN·2H2O and [FeL(NCS)2]2[Fe(H2O)(NCS)5]·4H2O, has been reported. Both iron(III) complexes possess the same pentagonal-bipyramidal complex cation, while the nature of their anions depends on mole ratio of NH4SCN and FeCl3·6H2O used in reaction. Cytotoxic activity of new Fe(III) complexes, as well as of previously synthesized isothiocyanato Co(II), Ni(II), Mn(II), Zn(II) and Cd(II) complexes with the same ligand, was tested against five human cancer cell lines (HeLa, MDA-MB-453, K562, LS174 and A549) and normal cell line MRC-5. The best activity was observed in the case of Fe(III), Co(II) and Cd(II) complexes. The investigation of potential of these complexes to induce HeLa and K562 cell cycle perturbations was also evaluated. Mechanism of cell death mode was elucidated on the basis of morphological changes of HeLa cells as well as identification of target caspases. It was established that DNA damage could be responsible for the activity of Fe(III) and Co(II) complexes. Pentagonal-bipyramidal Fe(III) complexes with dihydrazone of 2,6-diacetylpyridine and Girard's T reagent have been synthesized and characterized. Cytotoxic activity of Fe(III) complexes and Co(II), Ni(II), Mn(II), Zn(II) and Cd(II) complexes with the same ligand was tested. The best activity was observed in the case of Fe(III), Co(II) and Cd(II) complexes. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Abobotulinum - a toxin injection in patients with refractory idiopathic detrusor overactivity: injections in detrusor, trigone and bladder neck or prostatic urethra, versus detrusor - only injections.

    Science.gov (United States)

    Emami, Maryam; Shadpour, Pejman; Kashi, Amir H; Choopani, Masoud; Zeighami, Mohammadreza

    2017-07-20

    To evaluate if the injections of abobotulinum-A toxin in trigone and bladder neck/prostatic urethra in addition to detrusor provides better symptoms relief and urodynamic findings in patients with idiopathic detrusor overactivity (IDO) refractory to medical treatment. A total of 74 patients with IDO refractory to anticholinergics received injections in detrusor, trigone and bladder neck/prostatic urethra (Group A, N=36) versus detrusor only injections (Group B, N=38) of abobotulinum-A toxin. All patients were evaluated by a standard overactive bladder symptom score (OABSS) questionnaire and cystometrography before and 6 weeks after the operation. OABSS questionnaire was also completed 20 weeks after the operation. The magnitude of OABSS reduction from baseline to 6 weeks after operation in groups A and B patients was 13.4±2.2 versus 11.7±2.1 (p=0.001). Cystometry results were similar in both groups except for higher volume at urgent desire to void in Group B patients (p injection produces greater reductions in OABSS score and less residual urine volume but a lower volume at urgent desire to void in comparison with detrusor only injections. Copyright® by the International Brazilian Journal of Urology.

  6. Investigations of the optical and EPR data and local structure for the trigonal tetrahedral Co2+ centers in LiGa5O8: Co2+ crystal

    Science.gov (United States)

    He, Jian; Liao, Bi-Tao; Mei, Yang; Liu, Hong-Gang; Zheng, Wen-Chen

    2018-01-01

    In this paper, we calculate uniformly the optical and EPR data for Co2+ ion at the trigonal tetrahedral Ga3+ site in LiGa5O8 crystal from the complete diagonalization (of energy matrix) method founded on the two-spin-orbit-parameter model, where the contributions to the spectroscopic data from both the spin-orbit parameter of dn ion (in the classical crystal field theory) and that of ligand ions are contained. The calculated ten spectroscopic data (seven optical bands and three spin-Hamiltonian parameters g//, g⊥ and D) with only four adjustable parameters are in good agreement with the available observed values. Compared with the host (GaO4)5- cluster, the great angular distortion and hence the great trigonal distortion of (CoO4)6- impurity center obtained from the calculations are referred to the large charge and size mismatch substitution. This explains reasonably the observed great g-anisotropy Δg (= g// - g⊥) and zero-field splitting D for the (CoO4)6- cluster in LiGa5O8: Co2+ crystal.

  7. A technique for resection of invasive tumors involving the trigone area of the bladder in dogs: preliminary results in two dogs.

    Science.gov (United States)

    Saulnier-Troff, Francois-Guillaume; Busoni, Valeria; Hamaide, Annick

    2008-07-01

    To describe a surgical technique for resection of the entire bladder neck, including the trigone and proximal urethra in dogs with invasive tumors causing life-threatening urinary tract obstruction. Clinical case reports. Dogs (n=2) with bladder tumors. Circumferential excision of the bladder neck and proximal urethra with preservation of the neurovascular pedicles was performed to remove a rhabdomyosarcoma (dog 1) and a transitional cell carcinoma (dog 2) involving the trigone and bladder neck that were causing urinary tract obstruction. Reconstruction of the bladder and proximal urethra included bilateral ureteroneocystostomy. Adjuvant chemotherapy was administered postoperatively to both dogs. Postoperatively, dogs 1 and 2 were continent after 7 and 17 days, respectively, and regained normal urinary function after resolution of a transient pollakiuria. Dog 1 had no evidence of local or regional recurrence; however, a large solitary pulmonary metastatic lesion was diagnosed 8 months later. The dog was euthanatized despite a lack of clinical signs. Dog 2 had at least 1 metastatic lesion in the abdominal wall 6 months later and was euthanatized at 580 days because of renal failure. En-bloc removal of the bladder neck and proximal urethra with preservation of the dorsal vascular and nervous pedicles, although a technically challenging procedure, can be performed without associated urinary incontinence or bladder wall necrosis. In dogs with invasive bladder tumors causing life-threatening urinary tract obstruction, resection of the bladder neck and proximal urethra should be considered as a promising surgical alternative to urinary diversion.

  8. The next chapter in MOF pillaring strategies: Trigonal heterofunctional ligands to access targeted high-connected three dimensional nets, isoreticular platforms

    KAUST Repository

    Eubank, Jarrod F.

    2011-11-09

    A new pillaring strategy, based on a ligand-to-axial approach that combines the two previous common techniques, axial-to-axial and ligand-to-ligand, and permits design, access, and construction of higher dimensional MOFs, is introduced and validated. Trigonal heterofunctional ligands, in this case isophthalic acid cores functionalized at the 5-position with N-donor (e.g., pyridyl- or triazolyl-type) moieties, are designed and utilized to pillar pretargeted two-dimensional layers (supermolecular building layers, SBLs). These SBLs, based on edge transitive Kagomé and square lattices, are cross-linked into predicted three-dimensional MOFs with tunable large cavities, resulting in isoreticular platforms. © 2011 American Chemical Society.

  9. Detailed ab initio first-principles study of the magnetic anisotropy in a family of trigonal pyramidal iron(II) pyrrolide complexes.

    Science.gov (United States)

    Atanasov, Mihail; Ganyushin, Dmitry; Pantazis, Dimitrios A; Sivalingam, Kantharuban; Neese, Frank

    2011-08-15

    A theoretical, computational, and conceptual framework for the interpretation and prediction of the magnetic anisotropy of transition metal complexes with orbitally degenerate or orbitally nearly degenerate ground states is explored. The treatment is based on complete active space self-consistent field (CASSCF) wave functions in conjunction with N-electron valence perturbation theory (NEVPT2) and quasidegenerate perturbation theory (QDPT) for treatment of magnetic field- and spin-dependent relativistic effects. The methodology is applied to a series of Fe(II) complexes in ligand fields of almost trigonal pyramidal symmetry as provided by several variants of the tris-pyrrolylmethyl amine ligand (tpa). These systems have recently attracted much attention as mononuclear single-molecule magnet (SMM) complexes. This study aims to establish how the ligand field can be fine tuned in order to maximize the magnetic anisotropy barrier. In trigonal ligand fields high-spin Fe(II) complexes adopt an orbitally degenerate (5)E ground state with strong in-state spin-orbit coupling (SOC). We study the competing effects of SOC and the (5)E⊗ε multimode Jahn-Teller effect as a function of the peripheral substituents on the tpa ligand. These subtle distortions were found to have a significant effect on the magnetic anisotropy. Using a rigorous treatment of all spin multiplets arising from the triplet and quintet states in the d(6) configuration the parameters of the effective spin-Hamiltonian (SH) approach were predicted from first principles. Being based on a nonperturbative approach we investigate under which conditions the SH approach is valid and what terms need to be retained. It is demonstrated that already tiny geometric distortions observed in the crystal structures of four structurally and magnetically well-documented systems, reported recently, i.e., [Fe(tpa(R))](-) (R = tert-butyl, Tbu (1), mesityl, Mes (2), phenyl, Ph (3), and 2,6-difluorophenyl, Dfp (4), are enough to

  10. Chlorido-bis-(1,10-phenanthroline-κ(2) N,N')copper(II) chlorido-(1,10-phen-anthroline-κ(2) N,N')(pyridine-2,6-di-carboxyl-ato-κ(3) O (2),N,O (6))manganate(II) methanol monosolvate

    National Research Council Canada - National Science Library

    Buvailo, Halyna I; Rusanova, Julia A; Makhankova, Valeriya G; Kokozay, Vladimir N; Zubatyuk, Roman I

    2014-01-01

    .... Only the atoms used in the refined model are reported in chemical formula and related values. The Cu(II) ion is five-coordinated by two phenanthroline ligands and one chloride ion in a distorted trigonal-bipyramidal geometry...

  11. Acetonitrilebis(2,9-dimethylphenanthroline)copper(II) bis(tetrafluoridoborate) acetonitrile disolvate

    National Research Council Canada - National Science Library

    Watton, Stephen P

    2009-01-01

    ...(5) square-pyramidal geometry with the acetonitrile N atom in an equatorial site, which differs substanti-ally from the distorted trigonal-bipyramidal arrangement usually observed for five-coordinate complexes of Cu(II...

  12. NEW THIO S2- ADDUCTS WITH ANTIMONY (III AND V HALIDE: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    HASSAN ALLOUCH

    2013-12-01

    Full Text Available Five new S2- adducts with SbIII and SbV halides have been synthesized and studied by infrared. Discrete structures have been suggested, the environment around the antimony being tetrahedral, trigonal bipyramidal or octahedral.

  13. (Acetonitrile){2-[bis-(pyridin-2-ylmethyl-κ(2)N)amino-κN]-N-(2,6-dimethyl-phen-yl)acetamide-κO}(perchlorato-κO)zinc (acetonitrile){2-[bis-(pyridin-2-ylmethyl-κ(2)N)amino-κN]-N-(2,6-dimethyl-phen-yl)acetamide-κO}zinc tris-(perchlorate)

    National Research Council Canada - National Science Library

    Astrand, Ove Alexander Høgmoen; Görbitz, Carl Henrik; Kristoffersen, Kenneth Aase; Rongved, Pål

    2013-01-01

    .... In the first complex, the metal ion is coordinated by the N,N',N'',O-tetra-dentate acetamide ligand and an acetonitrile N atom, generating an approximate trigonal-bipyramidal coordination geometry...

  14. Synthesis and crystal structure of Mg{sub 0.5}NbO{sub 2}: An ion-exchange reaction with Mg{sup 2+} between trigonal [NbO{sub 2}]{sup -} layers

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Akira, E-mail: amiura@yamanashi.ac.jp [Center for Crystal Science and Technology, University of Yamanashi (Japan); Takei, Takahiro; Kumada, Nobuhiro [Center for Crystal Science and Technology, University of Yamanashi (Japan)

    2013-01-15

    A new layered niobate, Mg{sub 0.5}NbO{sub 2}, was synthesized from LiNbO{sub 2} through a cation-exchange reaction with Mg{sup 2+} at 450-550 Degree-Sign C. This is the first example of a topotactic reaction with an aliovalent cation between trigonal [NbO{sub 2}]{sup -} layers. It is proposed to be isostructural with LiNbO{sub 2} (space group; P6{sub 3}/mmc) with lattice parameters of a=2.9052(6) A, c=10.625(15) A. The lattice parameters and formation energy of Mg{sub 0.5}NbO{sub 2} crystallized in LiNbO{sub 2} form and other layered CaNb{sub 2}O{sub 4} one were calculated by density functional theory. - Graphical abstract: A new layered niobate, Mg{sub 0.5}NbO{sub 2}, was synthesized from LiNbO{sub 2} through a cation-exchange reaction with Mg{sup 2+} at 450-550 Degree-Sign C. It is isostructural with LiNbO{sub 2} with lattice parameters of a=2.9052(6) A, c=10.625(15) A. Mg{sup 2+} are described in spheres located between [NbO{sub 2}]{sup -} trigonal layers and its occupancy is 0.5. Highlights: Black-Right-Pointing-Pointer A new layered niobate, Mg{sub 0.5}NbO{sub 2}, was synthesized from LiNbO{sub 2}. Black-Right-Pointing-Pointer Cation-exchange reaction converted two monovalent Li{sup +} into one divalent Mg{sup 2+} at 450-550 Degree-Sign C. Black-Right-Pointing-Pointer Mg{sub 0.5}NbO{sub 2} was isostructural with LiNbO{sub 2} (space group; P6{sub 3}/mmc). Black-Right-Pointing-Pointer Its lattice parameters were a=2.9052(6) A and c=10.625(15) A. Black-Right-Pointing-Pointer Synthesized Mg{sub 0.5}NbO{sub 2} was calculated to be thermodynamically more favorable.

  15. Syntheses, structures and luminescence of three copper(I) cyanide coordination polymers based on trigonal 1,3,5-tris(1H-imidazol-1-yl)benzene ligand

    Science.gov (United States)

    Shao, Min; Li, Ming-Xing; Lu, Li-Ruo; Zhang, Heng-Hua

    2016-09-01

    Three Cu(I)-cyanide coordination polymers based on trigonal 1,3,5-tris(1H-imidazol-1-yl)benzene (tib) ligand, namely [Cu3(CN)3(tib)]n (1), [Cu4(CN)4(tib)]n (2), and [Cu2(CN)2(tib)]n (3), have been prepared and characterized by elemental analysis, IR, PXRD, thermogravimetry and single-crystal X-ray diffraction analysis. Complex 1 displays a 3D metal-organic framework with nanosized pores. Complex 2 is a 3D coordination polymer assembled by three μ2-cyanides and a μ3-cyanide with a very short Cu(I)···Cu(I) metal bond(2.5206 Å). Complex 3 is a 2D coordination polymer constructing from 1D Cu(I)-cyanide zigzag chain and bidentate tib spacer. Three Cu(I) complexes are thermally stable up to 250-350 °C. Complexes 1-3 show similar orange emission band at 602 nm originating from LMCT mechanism.

  16. Normal mode calculations of trigonal selenium

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; McMurry, H. L.

    1980-01-01

    . With such coordinates a potential energy, calculated with only a diagonal force matrix, is equivalent to one calculated with both off diagonal and diagonal elements when conventional coordinates are used. Another advantage is that often some force constants may be determined directly from frequencies at points of high....... In this way we have eliminated the ambiguity in the choice of valence coordinates, which has been a problem in previous models which used valence type interactions. Calculated sound velocities and elastic moduli are also given. The Journal of Chemical Physics is copyrighted by The American Institute...

  17. Trigonal Based Copper Sites - A Natural Situation?

    OpenAIRE

    Coyle, Joanne Lyssa

    2000-01-01

    This thesis is concerned with the synthesis and characterisation of copper model compounds which are of interest in a biological context. These model compounds fall into two main classes; iminopodands and azacryptands. The iminopodands are derived from the condensation of tris(2- aminoethy1)amine (tren) or tris(3-aminoisopropy1)amine (trpn) and a range of aromatic aldehydes. The compounds invariably co-ordinated Cu(1) and the structural consequences of the flexibility are examined and systema...

  18. SYNTHESIS AND INFRARED STUDY OF SOME NEW IODATO ADDUCTS AND DERIVATIVES

    Directory of Open Access Journals (Sweden)

    HASSAN ALLOUCH

    2014-05-01

    Full Text Available Three iodato adducts and one derivative have been synthesized and studied by infrared data. The suggested structures are discrete, the iodate behaving as a mono- or bidentate ligand, or an infinite chain with bridging iodate, the environment around the tin centre being trigonal bipyramidal, tetrahedral or octahedral.

  19. Modeling Finite Deformations in Trigonal Ceramic Crystals with Lattice Defects

    Science.gov (United States)

    2010-02-08

    sapphire from 15 to 420 kbar. The effects of large anisotropic compressions. J. Phys. Chem. Solids 32, 2311–2330. Heuer, A.H., 1966. Deformation twinning in...Horstemeyer, M.F., Korellis, J.S., Grishabar, R.B., Mosher, D., 1998. High temperature sensitivity of notched AISI 304L stainless steel tests. Theor

  20. An anti-ferromagnetic terephthalate-bridged trigonal prismatic ...

    Indian Academy of Sciences (India)

    SUBHASIS ROYa, SUMITAVA KHANa, JOAN RIBASb and BARINDRA KUMAR GHOSHa,∗. aDepartment of Chemistry, The University of Burdwan, Burdwan 713104, India. bDepartament de Quimica Inorganica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain e-mail: barin_1@yahoo.co.uk. MS received 26 ...

  1. Trigonal cavernous angioma presenting with selective ventricular exclusion.

    Science.gov (United States)

    Prada, F; Saladino, A; Giombini, S

    2010-12-01

    We present a case of a patient with an intraventricular cavernous angioma originating from the splenium of the corpus callosum presenting with intracranial hypertension syndrome. In our case the growth of the lesion from the corpus callosum toward the ventricular spaces determined the direct exclusion of the occipital and temporal horn of the left lateral ventricle.

  2. Sensing of aqueous fluoride anions by cationic stibine-palladium complexes.

    Science.gov (United States)

    Wade, Casey R; Ke, Iou-Sheng; Gabbaï, François P

    2012-01-09

    Turn on the lantern! The stibine donor ligand of a cationic palladium complex acts as a Lewis acid and reacts with a fluoride anion to afford the corresponding fluorostiboranyl-palladium species (see scheme). Bindung of the fluoride anion to the antimony center induces a change in denticity of the triphosphine unit and leads to a bright-orange trigonal-bipyramidal d(8) lantern complex. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Fluoride-bridged {GdIII3MIII2} (M=Cr, Fe, Ga) molecular magnetic refrigerants

    DEFF Research Database (Denmark)

    Pedersen, Kasper Steen; Lorusso, Giulia; Morales, Juan José

    2014-01-01

    The reaction of fac-[MIIIF3(Me3tacn)] ×x H2O with Gd(NO3)3×5H 2O affords a series of fluoride-bridged, trigonal bipyramidal {GdIII3MIII2} (M=Cr (1), Fe (2), Ga (3)) complexes without signs of concomitant GdF3 formation, thereby demonstrating the applicability even of labile fluoride-complexes as ...

  4. NEW HYDROGENOXALATO ADDUCTS AND MALONATO COMPLEX: SYNTHESIS AND SPECTROSCOPIC STUDIES

    Directory of Open Access Journals (Sweden)

    MOUHAMADOU BIRAME DIOP

    2014-08-01

    Full Text Available Two new hydrogenoxalato and one malonato adduct and complex have been synthesized and studied by infrared and NMR spectroscopies. The suggested structures are discrete, the hydrogenoxalate behaving as a monodentate ligand or only involved in hydrogen bonding, the environment around the tin (IV centre being tetrahedral or trigonal bipyramidal. The malonate anion is a monodentate ligand. In all the suggested structures, when extra hydrogen bonds are considered, supramolecular architectures are obtained.

  5. Ph3CCOOSnPh3.Ph3PO AND Ph3CCOOSnPh3.Ph3AsO: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    ABDOU MBAYE

    2014-08-01

    Full Text Available The mixture of ethanolic solutions of Ph3CCOOSnPh3 and Ph3PO or Ph3AsO gives Ph3CCOOSnPh3.Ph3PO and Ph3CCOOSnPh3.Ph3AsO adducts which have been characterized by infrared spectroscopy. A discrete structure is suggested for both, the environment around the tin centre being trigonal bipyramidal, the triphenylacetate anion behaving as a mondentate ligand.

  6. PHOSPHATO AND PHOSPHONATO ADDUCTS: SYNTHESIS AND SPECTROSCOPIC STUDY

    Directory of Open Access Journals (Sweden)

    Mouhamadou Birame Diop

    2014-05-01

    Full Text Available Two new adducts have been synthesized and studied by infrared and NMR spectroscopy. The suggested structures are discrete or of infinite chain type with a phosphate behaving as a bidentate ligand, a phosphonate acting as a monodentate ligand, the environments around the tin centre being tetrahedral or trigonal bipyramidal. In all the studied compounds, supramolecular architectures are obtained when hydrogen bonds are considered.

  7. Poly[μ2-aqua-(μ3-2,5-dichlorobenzenesulfonatosodium

    Directory of Open Access Journals (Sweden)

    Mohammad T. M. Al-Dajani

    2010-06-01

    Full Text Available In the title compound, [Na(C6H3Cl2O3S(H2O]n, the NaI ion is pentacoordinated by three dichlorobenzenesulfonate anions and two water molecules, forming a distorted trigonal-bipyramidal geometry. The NaI ions are bridged by the sulfonate groups and the water molecules, leading to a polymeric layer structure parallel to the bc plane in which O—H...O hydrogen bonds are observed.

  8. The molecular structure of trimethyltantalum dichloride, (CH 3) 3TaCl 2, as determined by gas electron diffraction

    Science.gov (United States)

    Haaland, Arne; Verne, Hans Peter; Volden, Hans Vidar; Pulham, Colin R.

    1996-02-01

    The gas electron diffraction data of (CH 3) 3TaCl 2, recorded with a nozzle temperature of about 25°C, show that the coordination geometry of the metal atom is trigonal bipyramidal with the Cl atoms in axial positions. Least-squares refinements based on a molecular model (hydrogen atoms excluded) of D3h symmetry yield the bond distances ( ra) TaC = 215.8(5) pm and TaCl = 231.7(3) pm.

  9. [Pr2(pdc3(Hpdc(H2O4]n·n(H3hp·8n(H2O, a One-Dimensional Coordination Polymer Containing PrO6N3 Tri-Capped Trigonal Prisms and PrO8N Mono-Capped Square Anti-Prisms (H2pdc = Pyridine 2,6-Dicarboxylic Acid, C7H5NO4; 3hp = 3-Hydroxy Pyridine, C5H5NO

    Directory of Open Access Journals (Sweden)

    Shahzad Sharif

    2012-08-01

    Full Text Available The synthesis, structure and some properties of the one-dimensional coordination polymer, [Pr2(pdc3(Hpdc]n·n(H3hp·8n(H2O, (H2pdc = pyridine 2,6-dicarboxylic acid, C7H5NO4; 3hp = 3-hydroxypyridine, C5H5NO are described. One of the Pr3+ ions is coordinated by two O,N,O-tridentate pdc2− ligands and one tridentate Hpdc− anion to generate a fairly regular PrO6N3 tri-capped trigonal prism, with the N atoms acting as the caps. The second Pr3+ ion is coordinated by one tridentate pdc2− dianion, four water molecules and two monodentate bridging pdc2− ligands to result in a PrO8N coordination polyhedron that approximates to a mono-capped square-anti-prism. The ligands bridge the metal-atom nodes into a chain, which extends in the [100] direction. The H3hp+ cation and uncoordinated water molecules occupy the inter-chain regions and an N–HLO and numerous O–HLO hydrogen bonds consolidate the structure. The H3hp+ species appears to intercalate between pendant pdc rings to consolidate the polymeric structure. Crystal data: 1 (C33H43N5O29Pr2, Mr = 1255.54, triclinic,  (No. 2, Z = 2, a = 13.2567(1 Å, b = 13.6304(2 Å, c = 13.6409(2 Å, α = 89.695(1°, β = 63.049(1°, γ = 86.105(1°, V = 2191.16(5 Å3, R(F = 0.033, wR(F2 = 0.084.

  10. Magnetic anisotropy of [Mo(CN)7]4- anions and fragments of cyano-bridged magnetic networks.

    Science.gov (United States)

    Chibotaru, Liviu F; Hendrickx, Marc F A; Clima, Sergiu; Larionova, Joulia; Ceulemans, Arnout

    2005-08-18

    Quantum chemistry calculations of CASSCF/CASPT2 level together with ligand field analysis are used for the investigation of magnetic anisotropy of [Mo(CN)7]4- complexes. We have considered three types of heptacyano environments: two ideal geometries, a pentagonal bipyramid and a capped trigonal prism, and the heptacyanomolybdate fragment of the cyano-bridged magnetic network K2[Mn(H2O)2]3[Mo(CN)7]2.6H2O. At all geometries the first excited Kramers doublet is found remarkably close to the ground one due to a small orbital energy gap in the ligand field spectrum, which ranges between a maximal value in the capped trigonal prism (800 cm(-1)) and zero in the pentagonal bipyramid. The small value of this gap explains (i) the axial form of the g tensor and (ii) the strong magnetic anisotropy even in strongly distorted complexes. Comparison with available experimental data for the g tensor of the mononuclear precursors reveals good agreement with the present calculations for the capped trigonal prismatic complex and a significant discrepancy for the pentagonal bipyramidal one. The calculations for the heptacyanomolybdate fragment of K2[Mn(H2O)2]3[Mo(CN)7]2.6H2O give g(perpendicular)/g(parallel) approximately 0.5 and the orientation of the local anisotropy axis close to the symmetry axis of an idealized pentagonal bipyramid. These findings are expected to be important for the understanding of the magnetism of anisotropic Mo(III)-Mn(II) cyano-bridged networks based on the [Mo(CN)7]4- building block.

  11. Size- and shape-controlled synthesis of hexagonal bipyramidal crystals and hollow self-assembled Al-MOF spheres

    KAUST Repository

    Sarawade, Pradip

    2013-11-25

    We report an efficient protocol for the synthesis of monodisperse crystals of an aluminum (Al)-based metal organic framework (MOF) while obtaining excellent control over the size and shape solely by tuning of the reaction parameters without the use of a template or structure-directing agent. The size of the hexagonal crystals of the Al-MOF can be selectively varied from 100 nm to 2000 nm by simply changing the reaction time and temperature via its nucleation-growth mechanism. We also report a self-assembly phenomenon, observed for the first time in case of Al-MOF, whereby hollow spheres of Al-MOF were formed by the spontaneous organization of triangular sheet building blocks. These MOFs showed broad hysteresis loops during the CO2 capture, indicating that the adsorbed CO2 is not immediately desorbed upon decreasing the external pressure and is instead confined within the framework, which allows for the capture and subsequent selective trapping of CO2 from gaseous mixtures. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Crystal structure of catena-poly[N,N,N′,N′-tetramethylguanidinium [(chloridocadmate-di-μ-chlorido

    Directory of Open Access Journals (Sweden)

    Mamadou Ndiaye

    2016-01-01

    Full Text Available In the structure of the title salt, {(C5H14N3[CdCl3]}n, the CdII atom of the complex anion is five-coordinated by one terminal and four bridging Cl atoms. The corresponding coordination polyhedron is a distorted trigonal bipyramid, with Cd—Cl distances in the range 2.4829 (4–2.6402 (4 Å. The bipyramids are condensed into a polyanionic zigzag chain extending parallel to [101]. The tetramethylguanidinium cations are situated between the polyanionic chains and are linked to them through N—H...Cl hydrogen bonds, forming a layered network parallel to (010.

  13. Water-coordinated neutral silane complex: a frozen intermediate of hydrolysis of alkoxysilanes.

    Science.gov (United States)

    Kobayashi, Junji; Kawaguchi, Keiko; Kawashima, Takayuki

    2004-12-22

    1-Aquo- and 1-ethyloxonio-5-carbasilatranes 2 and 3 were synthesized. X-ray crystallographic analysis revealed that 2 has a nearly ideal trigonal bipyramidal structure, in which the water molecule is located at the apical position. This water molecule is exchangeable with the other Lewis bases, such as H218O and HMPA. Theoretical calculations suggested that 2 would acquire the stabilization energy (20 kcal mol-1) by complexation. Deprotonation of 2 by pyridine and not by m-nitroaniline showed that the pKa value is smaller than that of free water, and that the water molecule is activated by complexation.

  14. Room-Temperature Ferrimagnet with Frustrated Antiferroelectricity: Promising Candidate Toward Multiple-State Memory

    Science.gov (United States)

    Wang, P. S.; Xiang, H. J.

    2014-01-01

    On the basis of first-principles calculations, we show that the M-type hexaferrite BaFe12O19 exhibits frustrated antiferroelectricity associated with its trigonal bipyramidal Fe3+ sites. The ferroelectric state of BaFe12O19, reachable by applying an external electric field to the antiferroelectric state, can be made stable at room temperature by appropriate element substitution or strain engineering. Thus, M-type hexaferrite, as a new type of multiferoic with coexistence of antiferroelectricity and ferrimagnetism, provides a basis for studying the phenomenon of frustrated antiferroelectricity and realizing multiple-state memory devices.

  15. catena-Poly[[aqua(1,10-phenanthrolinecobalt(II]-μ-4,4′-(propane-1,3-diyldioxydibenzoato

    Directory of Open Access Journals (Sweden)

    Su-Mei Shen

    2009-10-01

    Full Text Available In the title compound, [Co(C17H14O6(C12H8N2(H2O]n, the CoII atom is coordinated by a monodentate 4,4′-(propane-1,3-diyldioxydibenzoate (cpp dianion, a water molecule and a chelating 1,10-phenanthroline (phen ligand. A symmetry-generated cpp ligand completes the CoN2O3 trigonal-bipyramidal geometry for the metal ion, with the N atoms occupying both equatorial and axial sites. The bridging cpp ligands form chains propagating in [110] and O—H...O hydrogen bonds consolidate the packing.

  16. Crystal structure of [tris-(pyridin-2-ylmeth-yl)amine-κ(4) N]copper(II) bromide.

    Science.gov (United States)

    Bridgman, Emma C; Doherty, Megan M; Ellis, Kaleigh A; Homer, Elizabeth A; Lashbrook, Taylor N; Mraz, Margaret E; Pernesky, Gina C; Vreeke, Emma M; Oshin, Kayode D; Oliver, Allen G

    2016-06-01

    In the asymmetric unit of the title compound, [CuBr(C18H18N4)]Br, there are three crystallographically independent cations. One of the cations exhibits positional disorder of the pyridin-2-yl-methyl groups over two sets of sites with refined occupancies of 0.672 (8) and 0.328 (8). The outer-sphere bromine counter-ion is severely disordered over multiple sites. In each cation, the Cu(II) ion is coordinated by the four N atoms of the tris-(pyridin-2-ylmeth-yl)amine ligand and one bromine and adopts a slightly distorted trigonal-bipyramidal geometry.

  17. Cyanidotetra-kis-(trimethyl-phosphine)cobalt(I).

    Science.gov (United States)

    Xu, Xiaofeng; Feng, Lei; Li, Xiaoyan

    2011-04-01

    The title compound, [Co(CN)(C(3)H(9)P)(4)], was obtained as a product of the reaction of [Co(PMe(3))(4)] with a molar equivalent of 2,6-difluoro-benzonitrile in diethyl ether. This compound is stable in the air for several hours, but rapidly decomposes at room temperature in solution. The cobalt(I) atom has s trigonal-bipyramidal coordination enviroment in which the cyano group and one of the PMe(3) groups are in the axial positions.

  18. Bu4NSO4SnPh3•Ph3PO: SYNTHESIS AND SPECTROSCOPIC STUDIES

    Directory of Open Access Journals (Sweden)

    Bernard Mahieu

    2011-02-01

    Full Text Available On allowing Bu4NSO4SnPh3 to react with Ph3PO, the adduct Bu4NSO4SnPh3•Ph3PO is obtained. The IR and Mössbauer data allow to conclude to the cleavage of the Bu4NSO4SnPh3 chain and the coordination of Ph3PO to the tin (IV centre leading to discrete ionic structure containing a trans bipyramidal trigonal SnC3O2 arrangement with SO42- and Ph3PO being in an apical positions.

  19. Synthesis, spectroscopic and biological investigations of di-and triorganotin(IV derivatives containing germanium: X-ray study of [Ph3GeCH(n-C3H7CH2CO2]Sn[CH3]3

    Directory of Open Access Journals (Sweden)

    MASOOD PARVEZ

    2006-10-01

    Full Text Available Bimetallic di- and triorganotin(IV germanium carboxylates were synthesized and characterized by elemental analyses, as well as IR, multinuclear NMR (1H, 13C, 119Sn spectroscopy and tested for bioactivity. The structure of the representative compound, [Ph3GeCH(n-C3H7CH2CO2]Sn[CH3]3 was determined by X-ray analysis and found to have a distorted trigonal bipyramidal geometry around the tin atom. Some selected compounds were also screened against different microbes and showed promising antibacterial and antifungal activity.

  20. Tribenzylbis(triphenylarsine oxide-κOtin(IV tetraphenylborate

    Directory of Open Access Journals (Sweden)

    Thy Chun Keng

    2010-11-01

    Full Text Available The crystal structure of the title salt, [Sn(C7H73(C18H15AsO2][B(C6H54], consists of discrete cations and anions; the tin atom of the cation is five-coordinated in a distorted trans-C3SnO2 trigonal-bipyramidal geometry [summation of C–Sn–C angles 360.0 (3° and O–Sn–O angle 173.1 (1°]. The structure contains voids of 113 (19 Å3, but no solvent molecule could reasonably be located there.

  1. Metal (M) dopant centred local structures, high-pressure synthesis and bulk superconductivity in YBa sub 2 (Cu sub 1 sub - sub x M sub x) sub 3 O sub 7 sub - subdelta: M = Fe, Co, Ni

    CERN Document Server

    Shi, F; Bresser, W J; Boolchand, P; McDaniel, D

    1997-01-01

    Depression of T sub c by the dopants Fe or Co, but not Ni, is spectacularly reversed by synthesis of the titled cuprates at high P instead of ambient P of oxygen with T sub c enhanced from 32 to 82 K for M=Fe at x=0.10. With Fe dopant, Moessbauer spectroscopy reveals a conversion of a tetrahedral (A) into a trigonal bipyramidal coordinated (C) Fe chain site by oxygen addition in the chains upon high-P processing. The A->C site transformation is elucidated and extended to the case of Co dopant, and its consequences for superconducting behaviour discussed. (author). Letter-to-the-editor

  2. Salicylato[tris(N-methylbenzimidazol-2-ylmethylamine]zinc(II perchlorate dimethylformamide sesquisolvate

    Directory of Open Access Journals (Sweden)

    Huilu Wu

    2008-01-01

    Full Text Available In the title complex, [Zn(C7H5O3(C27H27N7]ClO4·1.5C3H7NO, the ZnII atom is five-coordinated by four N atoms from a tris(N-methylbenzimidazol-2-ylmethylamine ligand and one O atom from a salicylate ligand in a distorted trigonal-bipyramidal geometry (τ parameter = 0.84, with approximate molecular C3 symmetry. One dimethylformamide molecule lies on a general position and is disordered over two coplanar orientations with equal occupancy. A second dimethylformamide molecule is disordered about a twofold rotation axis.

  3. 12-Chloro-6-cyclohexyl-5,6,7,12-tetrahydrodibenzo[c,f][1,5]azastibocine

    Directory of Open Access Journals (Sweden)

    Weiguo Yi

    2011-07-01

    Full Text Available In the title organometallic complex, [Sb(C20H23NCl], the central antimony-containing part of the complex exhibits a pseudo-trigonal-bipyramidal geometry, where two C atoms and a lone electron pair of the Sb atom exist at the equatorial positions, while the N and Cl atoms are located at the apical positions, and a transannular interaction exists between the Sb and N atoms on 1,5-azastibocine. Intermolecular C—H...Cl hydrogen bonds are also observed.

  4. catena-Poly[[tris(4-fluorobenzyltin(IV]-μ-2-[(piperidin-1-ylcarbothioylsulfanyl]acetato-κ2O:O′

    Directory of Open Access Journals (Sweden)

    Chun Thy Keng

    2010-08-01

    Full Text Available Adjacent units of the title polymeric complex, [Sn(C7H6F3(C8H12NO2S2], are bridged by the carboxylate ion into a helical chain running along the b axis. The Sn(IV atom shows a distorted trans-C3SnO2 trigonal-bipyramidal coordination and is displaced by 0.113 (2 Å out of the C3Sn girdle in the direction of the covalently bonded O atom. The ring is disordered of two positions with an occupancy of 0.631 (4 for the major occupied site.

  5. Reductive cleavage of nitrite to form terminal uranium mono-oxo complexes.

    Science.gov (United States)

    Lewis, Andrew J; Carroll, Patrick J; Schelter, Eric J

    2013-01-09

    Uranium terminal mono-oxo complexes are prepared with a unique activation of nitrite following reductive cleavage of an N-O bond with loss of nitric oxide. The thermodynamic driving force of U═O bond formation differentiates this reactivity from known mechanisms of nitrite reduction, which are typically mediated by proton transfer. Mechanistic details are explored by DFT supporting a simple homolytic cleavage pathway from a κ(1)-ONO bound intermediate. Complexes of the formula U(VI)OX[N(SiMe(3))(2)](3) are formed providing a trigonal bipyramidal framework into which ligands trans to the U═O bond may be installed.

  6. Nitrogen-doped graphene anchored with mixed growth patterns of CuPt alloy nanoparticles as a highly efficient and durable electrocatalyst for the oxygen reduction reaction in an alkaline medium.

    Science.gov (United States)

    Illathvalappil, Rajith; Dhavale, Vishal M; Bhange, Siddheshwar N; Kurungot, Sreekumar

    2017-07-06

    A highly active and durable CuPt alloy catalyst with trigonal bipyramidal and truncated cube-type mixed morphologies, anchored on the nitrogen-doped graphene (NGr) surface (CuPt-TBTC/NGr), was prepared by a simple and fast method. The obtained CuPt alloy showed improved oxygen reduction reaction (ORR) activity, with a 30 mV positive shift in the half-wave potential value, as compared to the state-of-the-art Pt/C catalyst in a 0.1 M KOH solution. The CuPt alloy with the trigonal bipyramidal morphology possesses porous type inter-connected sides, which help to achieve improved mass transport of oxygen during the ORR. The exposure of the (111) plane of the CuPt alloy further improved the catalytic activity towards the dioxygen reduction in alkaline media. The ORR activity of the NGr-supported CuPt alloy was found to be dependent on the reaction time, and improved activity was obtained on the material derived at a reaction time of 90 min (CuPt-TBTC/NGr-90). The material synthesized at a lower or higher reaction time than 90 min resulted in a partially formed trigonal bipyramidal morphology with more truncated cubes or agglomerated trigonal bipyramidal and truncated cubes with closed type structures, respectively. Along with the high intrinsic ORR activity, CuPt-TBTC/NGr-90 displayed excellent electrochemical stability. Even after repeated 1000 potential cycling in a window ranging from 0.10 to 1.0 V (vs. RHE), the system clearly outperformed the state-of-the-art Pt/C catalyst with 15 and 60 mV positive shifts in the onset and half-wave potentials, respectively. CuPt-TBTC/NGr-90 also exhibited 2.1 times higher mass activity and 2.2 times higher specific activity, compared to Pt/C at 0.90 V (vs. RHE). Finally, a zinc-air battery fabricated with the alloy catalyst as the air electrode displayed a peak power density of 300 mW cm -2 , which is much higher than the peak power density of 253 mW cm -2 obtained for the state-of-the-art Pt/C catalyst as the air electrode.

  7. The molecular structure of dimethyltellurium dichloride by gas electron diffraction and ab initio calculations at the MP2 level

    Science.gov (United States)

    Haaland, Arne; Martinsen, Kjell-Gunnar; Tafipolsky, Maxim A.; Volden, Hans Vidar; Rösler, Roland; Breunig, Hans Joachim

    1997-09-01

    Ab initio calculations at the MP2 level and gas electron-diffraction data of (CH 3) 2TeCl 2 show that the molecular structure is pseudo-trigonal bipyramidal with the two methyl groups occupying equatorial positions and the two Cl atoms axial positions. The bond distances are ( {GED}/{MP2 }): TeC = 213.2(5)/214.6 pm, TeCl = 250.4(3)/261.8 pm and the valence angles ∠ CTeC = {97(5)°}/{97.6°}; ∠ ClTeCl = {170(2)°}/{170.8°}.

  8. (2-{[1,1-Bis(hydroxymethyl-2-oxidoethyl]iminomethyl}-4-chlorophenolato-κ3O,N,O′dibutyltin(IV

    Directory of Open Access Journals (Sweden)

    See Mun Lee

    2010-07-01

    Full Text Available In the title compound, [Sn(C4H92(C11H12BrNO4], the Schiff base ligand chelates to the SnIV atom through the two deprotonated hydroxy groups, as well as through the N atom, to confer an overall cis-C2SnNO2 trigonal-bipyramidal geometry at the SnIV atom [C—Sn—C = 129.92 (9°]. The remaining methylenehydroxy groups engage in O—H...O hydrogen bonding with the O atoms of adjacent molecules, leading to infinite supramolecular chains propagating in [001].

  9. [N′-(5-Bromo-2-oxidobenzylidene-κO-3-hydroxy-2-naphthohydrazidato-κ2N′,O]dicyclohexyltin(IV

    Directory of Open Access Journals (Sweden)

    See Mun Lee

    2010-02-01

    Full Text Available The environment at the SnIV atom in the title compound, [Sn(C6H112(C18H11BrN2O3], is distorted trigonal-bipyramidal, with the two cyclohexyl groups and the imino N atom forming the equatorial plane. The axial O—Sn—O angle is 155.97 (9°. The presence of an intramolecular O—H...N hydrogen bond in the Schiff base ligand helps to stabilize the overall structure.

  10. (N-sec-Butyl-N-n-propyldithiocarbamato-κ2S,S′triphenyltin(IV

    Directory of Open Access Journals (Sweden)

    Normah Awang

    2010-09-01

    Full Text Available The Sn atom in the title compound, [Sn(C6H53(C8H16NS2], is pentacoordinated by two S atoms, derived from an asymmetrically coordinating dithiocarbamate ligand, and three ipso-C atoms. The coordination geometry is intermediate between square-pyramidal and trigonal-bipyramidal, with a leaning towards the latter. The presence of close intramolecular C—H...S contacts preclude the S atoms from forming significant intermolecular interactions. Rather, molecules are consolidated in the crystal structure by C—H...π interactions.

  11. (Diethylenetriaminebis(theophyllinatozinc(II dihydrate

    Directory of Open Access Journals (Sweden)

    Attila-Zsolt Kun

    2009-05-01

    Full Text Available In the title compound, [Zn(C7H7N4O22(C4H13N3]·2H2O, the ZnII ion is pentacoordinated by three N atoms of the diethylenetriamine ligand and one N atom of each of the two theophyllinate anions in a distorted trigonal-bipyramidal geometry. The Zn—N distances range from 2.076 (3 to 2.221 (3 Å. The crystal packing is stabilized by O—H...O, O—H...N and N—H...O hydrogen bonds involving the theophylline and diethylenetriamine ligands and uncoordinated water molecules.

  12. Crystal structure of hexa­kis­(dmpu)-di-μ2-hydroxido-dialuminium tetraiodide dmpu tetra­solvate [dmpu is 1,3-di­methyl­tetra­hydro­pyrimidin-2(1H)-one]: a centrosymmetric dinuclear aluminium complex containing AlO5 polyhedra

    OpenAIRE

    Daniel Lundberg; Krzysztof Lyczko

    2015-01-01

    The structure of the title compound, [Al2(OH)2(C6H12N2O)6]I4·4C6H12N2O (systematic name: di-μ2-hydroxido-bis{tris[1,3-dimethyltetrahydropyrimidin-2(1H)-one-κO]aluminium} tetraiodide 1,3-dimethyltetrahydropyrimidin-2(1H)-one tetrasolvate), is composed of two Al(C6H12N2O)3 moieties linked into a centrosymmetric dinuclear unit by a pair of bridging hydroxide ions. The aluminium cations show a distorted trigonal bipyramidal AlO5 coordination environment formed only by monodentate ligands. The Al—...

  13. catena-Poly[[triphenyl-tin(IV)]-μ-phenyl-phosphinato-κO:O'].

    Science.gov (United States)

    Diop, Tidiane; Diop, Libasse; Kociok-Köhn, Gabriele; Molloy, Kieran C; Stoeckli-Evans, Helen

    2011-12-01

    In the structure of the title coordination polymer, [Sn(C(6)H(5))(3)(C(6)H(6)O(2)P)](n) or [PhP(H)O(2)Sn(IV)(Ph)(3)](n), the Sn(IV) atom is five-coordinate, with the SnC(3)O(2) framework in a trans trigonal-bipyramidal arrangement having the PhP(H)O(2) (-) anions in apical positions. In the crystal, neighbouring polymer chains are linked via C-H⋯π inter-actions, forming a two-dimensional network lying parallel to (001).

  14. Structure of TeO2 - LiNbO3 glasses

    Science.gov (United States)

    Shinde, A. B.; Krishna, P. S. R.; Rao, Rekha

    2017-05-01

    Tellurite based lithium niobate glasses with composition (100-x)TeO2-xLiNbO3 (x=0.1,0.2 & 0.3) were prepared by conventional melt quenching method. The microscopic structural investigation of these glasses is carried out by means of neutron diffraction and Raman scattering measurements. It is found that the basic structural units in these glasses are TeO4 trigonal bipyramids(TBP), TeO3 trigonal pyramids(TP) and NbO6 Octahedra depending on the composition. It is evident from Raman studies that TBPs decreases, TPs increases and NbO6 Octahedra increases with increasing x. From Neutron diffraction studies it is found that network is comprised of TBPs and TPs along with TeO3+1 structural units. Distorted NbO6 octahedral units are present and also increase with the increase in x.

  15. A combined experimental, theoretical, and Van't Hoff model study for identity methyl, proton, hydrogen atom, and hydride exchange reactions. Correlation with three-center four-, three-, and two-electron systems

    Science.gov (United States)

    Buck, Henk M.

    We have studied carbon transfer reactions following an SN2 reaction profile. With ab initio calculations and experimental geometries concerning the nature of the various complexes indicated as stable, intermediate, and transition state we were able to show the additional value of van't Hoff's tetrahedral configuration by changing its geometry via a trigonal pyramid into a trigonal bipyramid. The ratio of the apical bond and corresponding tetrahedral bond distances is then nearly 1.333. The relevance of this approach has also been shown for identity proton-(hydrogen atom-, and hydride-) in-line reactions. The use of this geometrical transmission will be demonstrated for the hydrogen bonding distances in e.g., DNA duplexes and other biological (supra) molecular systems.

  16. A THIOLATO-BRIDGED OCTANUCLEAR COPPER(I,II MIXED- VALENCE COMPLEX WITH N,N,S-TRIDENTATE LIGAND

    Directory of Open Access Journals (Sweden)

    Takanori Kotera

    2007-06-01

    Full Text Available Thiolato-bridged complex [CuI4CuII4(peampt4Cl8]·2H2O (Hpeampt = 1-(2-pyridylethylamino methylpropane-2-thiol has been synthesized and characterized by the elemental analysis, IR and UV-vis spectroscopies and magnetic susceptibility measurement. The X-ray crystal structure analysis of this complex shows a localized mixed-valence octanuclear cage structure made up of four trigonal-bipyramidal CuIIN2SCl2, two trigonal CuIS2Cl, and two tetrahedral CuIS2Cl2 coordination sites. Temperature dependence of magnetic susceptibility (4.5— 300 K shows that a fairly strong antiferromagnetic interaction is operating between the four CuII ions.

  17. Hetero-metallic trigonal cage-shaped dimeric Ni 3 K core complex of ...

    Indian Academy of Sciences (India)

    ... of the reducing agent hydrogen peroxide involving hydroxyl radical (°OH) species. As evidenced from the control experiment, DNA cleavage in the presence of °OH radical was inhibited by quenchers, viz. DMSO and KI. The complex showed in vitro antimicrobial activity against four bacteria and two fungi and the activity is ...

  18. Activation of Small Molecules at Iron Complexes in Varying Trigonal Ligand Environments

    OpenAIRE

    Hohenberger, Johannes

    2017-01-01

    Iron nitrido and nitrosyl/nitroxyl model complexes have been of great interest owing to their role as reactive intermediates and transfer reagents and their role in biochemical reactions involving nitrogen and NO. The stable iron(IV) nitrido complex [(TIMENMes)FeIV(N)]BPh4 (TIMENMes = tris-[2 (3-mesitylimidazol-2 ylidene)¬ethyl]¬amine), synthesized by Meyer and co-workers in 2008, proved to be uncreative towards electrophiles or nucleophiles and thus, the increase of its reactivity was tested...

  19. The trigonal polymorph of strontium tetra-borate, β-SrB(4)O(7).

    Science.gov (United States)

    Vasiliev, Alexander D; Cherepakhin, Alexander V; Zaitsev, Alexander I

    2010-05-29

    The asymmetric unit of the title compound, β-SrB(4)O(7), contains five Sr atoms (three located on a threefold rotation axis), twelve B and 21 O atoms. The structure is made up from BO(3) triangles and BO(4) tetra-hedra in a 1:1 ratio. Pairs of BO(3) triangles are linked to BO(4) tetra-hedra via common corners, forming chains. These chains are further linked to adjacent chains through corner-sharing, leading to a three-dimensional framework with channels running parallel to [001]. The Sr(2+) ions reside in the channels and exhibit strongly distorted polyhedra The density of the β-polymorph is considerably lower than that of α-SrB(4)O(7), which is constructed solely from BO(4) tetra-hedra.

  20. Hetero-metallic trigonal cage-shaped dimeric Ni3K core complex of ...

    Indian Academy of Sciences (India)

    ence of the reducing agent hydrogen peroxide involving hydroxyl radical (. ◦. OH) species. As evidenced from the control experiment, DNA cleavage in the presence of. ◦. OH radical was inhibited by quenchers, viz. DMSO and KI. The complex showed in vitro antimicrobial activity against four bacteria and two fungi and the ...

  1. Magnetic Properties and Magnetic Phase Diagrams of Trigonal DyNi3Ga9

    Science.gov (United States)

    Ninomiya, Hiroki; Matsumoto, Yuji; Nakamura, Shota; Kono, Yohei; Kittaka, Shunichiro; Sakakibara, Toshiro; Inoue, Katsuya; Ohara, Shigeo

    2017-12-01

    We report the crystal structure, magnetic properties, and magnetic phase diagrams of single crystalline DyNi3Ga9 studied using X-ray diffraction, electrical resistivity, specific heat, and magnetization measurements. DyNi3Ga9 crystallizes in the chiral structure with space group R32. The dysprosium ions, which are responsible for the magnetism in this compound, form a two-dimensional honeycomb structure on a (0001) plane. We show that DyNi3Ga9 exhibits successive phase transitions at TN = 10 K and T'N = 9 K. The former suggests quadrupolar ordering, and the latter is attributed to the antiferromagnetic order. It is considered that DyNi3Ga9 forms the canted-antiferromagnetic structure below T'N owing to a small hysteresis loop of the low-field magnetization curve. We observe the strong easy-plane anisotropy, and the multiple-metamagnetic transitions with magnetization-plateaus under the field applied along the honeycomb plane. For Hallel [2\\bar{1}\\bar{1}0], the plateau-region arises every 1/6 for saturation magnetization. The magnetic phase diagrams of DyNi3Ga9 are determined for the fields along principal-crystal axes.

  2. Uranium pyrrolylamine complexes featuring a trigonal binding pocket and interligand noncovalent interactions.

    Science.gov (United States)

    Lewis, Andrew J; Williams, Ursula J; Kikkawa, James M; Carroll, Patrick J; Schelter, Eric J

    2012-01-02

    The syntheses of tri- and tetravalent uranium complexes of the Ar(F)(3)TPA(3-) ligand [Ar(F) = 3,5-bis(trifluoromethyl)phenyl; TPA = tris(pyrrolyl-α-methylamine)] are described. Interligand noncovalent interactions between arene groups within the complexes are detected both in the solid state and in solution.

  3. A closer look into close packing: pentacoordinated silicon in a high-pressure polymorph of danburite

    Directory of Open Access Journals (Sweden)

    Anna Pakhomova

    2017-09-01

    Full Text Available Due to their high technological and geological relevance, silicates are one of the most studied classes of inorganic compounds. Under ambient conditions, the silicon in silicates is almost exclusively coordinated by four oxygen atoms, while high-pressure treatment normally results in an increase in the coordination from four- to sixfold. Reported here is a high-pressure single-crystal X-ray diffraction study of danburite, CaB2Si2O8, the first compound showing a step-wise transition of Si coordination from tetrahedral to octahedral through a trigonal bipyramid. Along the compression, the Si2O7 groups of danburite first transform into chains of vertice-sharing SiO5 trigonal bipyramids (danburite-II and later into chains of edge-sharing SiO6 octahedra (danburite-III. It is suggested that the unusual formation of an SiO5 configuration is a consequence of filling up the pentacoordinated voids in the distorted hexagonal close packing of danburite-II.

  4. Crystal structure of Helicobacter pylori neutrophil-activating protein with a di-nuclear ferroxidase center in a zinc or cadmium-bound form

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Hideshi, E-mail: h-yokoya@u-shizuoka-ken.ac.jp [School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526 (Japan); Tsuruta, Osamu; Akao, Naoya; Fujii, Satoshi [School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526 (Japan)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Structures of a metal-bound Helicobacter pylori neutrophil-activating protein were determined. Black-Right-Pointing-Pointer Two zinc ions were tetrahedrally coordinated by ferroxidase center (FOC) residues. Black-Right-Pointing-Pointer Two cadmium ions were coordinated in a trigonal-bipyramidal and octahedral manner. Black-Right-Pointing-Pointer The second metal ion was more weakly coordinated than the first at the FOC. Black-Right-Pointing-Pointer A zinc ion was found in one negatively-charged pore suitable as an ion path. -- Abstract: Helicobacter pylori neutrophil-activating protein (HP-NAP) is a Dps-like iron storage protein forming a dodecameric shell, and promotes adhesion of neutrophils to endothelial cells. The crystal structure of HP-NAP in a Zn{sup 2+}- or Cd{sup 2+}-bound form reveals the binding of two zinc or two cadmium ions and their bridged water molecule at the ferroxidase center (FOC). The two zinc ions are coordinated in a tetrahedral manner to the conserved residues among HP-NAP and Dps proteins. The two cadmium ions are coordinated in a trigonal-bipyramidal and distorted octahedral manner. In both structures, the second ion is more weakly coordinated than the first. Another zinc ion is found inside of the negatively-charged threefold-related pore, which is suitable for metal ions to pass through.

  5. Multinuclear NMR and crystallographic studies of triorganotin valproates and their in vitro antifungal activities

    Science.gov (United States)

    de Morais, Bárbara P.; de Lima, Geraldo M.; Pinheiro, Carlos B.; San Gil, Rosane A. S.; Takahashi, Jacqueline A.; Menezes, Daniele C.; Ardisson, José D.

    2015-08-01

    The reactions of triorganotin chlorides and sodium valproate, Na(OVp), yielded three triorganotin valproates [{SnMe3(OVp)}n] (1), [{SnBu3(OVp)}n] (2) and [SnPh3(OVp)] (3). All complexes have been authenticated in terms of infrared, 1H and 13C NMR, and solution- and solid-state 119Sn NMR, 119Sn Mössbauer and X-ray crystallography. The 119Sn NMR experiments provided important informations concerning the structures of (1)-(3) in solution and in the solid state. The X-ray experiments revealed the double-polymeric chain of complex (1), in which the geometry at the Sn(IV) is trigonal bipyramidal with intermolecular valproate bridges. The structure of complex (3) was re-determined and the new data show the tin cation at the centre of a distorted trigonal bipyramid, and not coordinated by four electron donating groups. The biological activity of all derivatives has been screened in terms of IC50 (μmol L-1) against C. albicans (ATCC 18804), C. tropicalis (ATCC 750), C. glabrata (ATCC 90030), C. parapsilosis (ATCC 22019), C. lusitaniae (CBS 6936) and C. dubliniensis (clinical isolate 28). Complex (3) exhibited the best biocide activity.

  6. Low-dimensional compounds containing cyano groups. IV. Bis(2,2'-bipyridine-kappa(2)N,N1)(dicyanamido-kappaN')copper(II) perchlorate and mu-dicyanamido-kappa(2)N1:N5-bis[bis(2,2'-bipyridine-kappa(2)N,N')copper(II)] triperchlorate ethanol hemisolvate, complexes with unusual dicyanamide coordination.

    Science.gov (United States)

    Potocnák, Ivan; Burcák, Milan; Massa, Werner; Jäger, Lothar

    2002-10-01

    From reaction mixtures containing the same reagents, the two novel title complexes, with unusual coordination modes of the dicyanamide (dca) ligand, have been prepared. The first compound, [Cu(C(2)N(3))(C(10)H(8)N(2))(2)]ClO(4), represents a relatively rare class of compounds, with the dca ligand coordinated in a monodentate manner. Its structure is formed by the [Cu(bpy)(2)N(CN)(2)](+) complex cation (bpy is 2,2'-bipyridine) and a ClO(4)(-) anion, which does not enter the inner coordination sphere. The Cu centre is five-coordinate within a strongly distorted trigonal bipyramid to two bpy molecules and one dca ligand, which is coordinated through one nitrile N atom in the equatorial plane. The second compound, [Cu(2)(C(2)N(3))(C(10)H(8)N(2))(4)](ClO(4))(3).0.5C(2)H(6)O, contains dca coordinated in the more common bidentate manner, but instead of a chain structure, a unique binuclear complex is formed. The asymmetric unit consists of the [Cu(bpy)(2)N(CN)(2)(bpy)(2)Cu](3+) binuclear complex cation, the charge of which is neutralized by three uncoordinated perchlorate anions, and a half-molecule of ethanol. Both Cu centres in the cation are five-coordinate, adopting a slightly distorted trigonal-bipyramidal environment.

  7. Spectroscopic properties of some mixed ligand copper(II) complexes of N-(2-aminoethyl)-1,2-ethanediamine and ethanediamine and its alkylated derivatives

    Science.gov (United States)

    Sastry, B. A.; Chary, K. S.; Subramanian, R.; Ponticelli, G.; Puggioni, G.

    1992-04-01

    IR, EPR and electronic spectral studies have been made on a series of complexes with general formula [M(dien)L](BØ 4) 2nH 2O (M = Cu(II), Zn(II), Cd(II), dien = N-(2-aminoethyl)-1,2-ethanediamine, L = ethanediamine (en), Me 4en, Et 2en, Me = methyl, Et = ethyl, BØ 4 = tetraphenylborate, n = 0 or 2] taking copper(II) as a magnetic probe in polycrystalline and solution forms to obtain stereochemical information. A five-coordinate square-based pyramidal (SBP) geometry with CuN 3N' 2 moiety having moderately covalent metal-ligand σ-bonds is found to exist in unalkylated mixed ligand complexes. Among alkylated complexes [Cu/Cd(dien)(Me 4en)](BØ 4) 2 is found to possess two species having tetrahedral and SBP with trigonal bipyramidal distortion geometries unlike the other alkylated complexes which have indicated the presence of one species having SBP coordination geometry with varying degrees of trigonal bipyramidal distortions and metal-ligand σ-bond strengths. EPR studies in dilute dmf and pyridine solutions of copper(II) complexes indicated the presence of solute-solvent interaction.

  8. Structures of tin cluster cations Sn3(+) to Sn15(+).

    Science.gov (United States)

    Drebov, Nedko; Oger, Esther; Rapps, Thomas; Kelting, Rebecca; Schooss, Detlef; Weis, Patrick; Kappes, Manfred M; Ahlrichs, Reinhart

    2010-12-14

    We employ a combination of ion mobility measurements and an unbiased systematic structure search with density functional theory methods to study structure and energetics of gas phase tin cluster cations, Sn(n)(+), in the range of n = 3-15. For Sn(13)(+) we also carry out trapped ion electron diffraction measurements to ascertain the results obtained by the other procedures. The structures for the smaller systems are most easily described by idealized point group symmetries, although they are all Jahn-Teller distorted: D(3h) (trigonal bipyramid), D(4h) (octahedron), D(5h) (pentagonal bipyramid) for n = 5, 6, and 7. For the larger systems we find capped D(5h) for Sn(8)(+) and Sn(9)(+), D(3h) (tricapped trigonal prism) and D(4d) (bicapped squared antiprism) plus adatoms for n = 10, 11, 14, and 15. A centered icosahedron with a peripheral atom removed is the dominant motif in Sn(12)(+). For Sn(13)(+) the calculations predict a family of virtually isoenergetic isomers, an icosahedron and slightly distorted icosahedra, which are about 0.25 eV below two C(1) structures. The experiments indicate the presence of two structures, one from the I(h) family and a prolate C(1) isomer based on fused deltahedral moieties.

  9. Structures and energetics of small lead cluster ions.

    Science.gov (United States)

    Kelting, Rebecca; Otterstätter, Robin; Weis, Patrick; Drebov, Nedko; Ahlrichs, Reinhart; Kappes, Manfred M

    2011-01-14

    By a combination of gas phase ion mobility measurements and relativistic density functional theory calculations with inclusion of spin-orbit coupling, we assign structures of lead cluster cations and anions in the range between 4 and 15 atoms. We find a planar rhombus for the tetramer, a trigonal bipyramid for the pentamer, and a pentagonal bipyramid for the heptamer, independent of charge state. For the hexamer, the cation and anion structures differ: we find an octahedron for the anion while the cation consists of fused tetrahedra. For the octamer, we find in both cases structures based on the pentagonal bipyramid motif plus adatom. For the larger clusters investigated we always find different structures for cations and anions. For example, Pb(12)(-) is confirmed to be a hollow icosahedron while Pb(12)(+) is a truncated filled icosahedron. Pb(13)(+) is a filled icosahedron but Pb(13)(-) is a hollow icosahedron with the additional atom capping a face. In order to get experimental information on the relative stabilities, we investigated the collision induced dissociation mass spectra for the different cluster sizes and charge states, and observe a strong correlation with the calculated fragmentation energies. Up to n = 13 the main fragmentation channel is atom loss; for the larger cluster sizes we observe fission into two large fragments. This channel is dominant for larger anions, less pronounced but clearly present for the cations.

  10. Pankkiiri tekee maitotiliä / Anu Karttunen

    Index Scriptorium Estoniae

    Karttunen, Anu

    2005-01-01

    Investeerimispanga Trigon Capital ning selle juhi Joakim Heleniuse suurinvesteeringutest. Ülevaade Trigon Capitali ettevõtetest Idealnaja Tshashka, Trigon Baltic Farming, Trigon Gardening, Trigon Asset Management ja Trigon Corporate Finance

  11. Shock Wave Induced Transition from the Trigonal Phase to the - Existing Amorphous and Orthorhombic Phases in FePO_4

    Science.gov (United States)

    Joshi, K. D.; Suresh, N.; Jyoti, G.; Gupta, S. C.; Kulshreshtha, S. K.; Sikka, S. K.

    1997-07-01

    The shock wave induced response of the berlinite form, α-FePO_4, (which has been studied recently under static pressures [Chitra et al. 1997] ) has been investigated in order to examine the effect of shear and high temperature on the process of amorphization in this material. The samples, recovered after shock loading upto 8.5 GPa in a gas gun, were analysed using powder x-ray diffraction (XRD) technique. The sample retrieved from 5.2 GPa clearly revealed an irreversible phase transformation of some of the material to an amorphous and a crystalline structure (space group Cmcm), which are co-existing. The XRD pattern of the 8.5 GPa sample on the other hand displayed the presence of only the orthorhombic phase along with the ambient structure. This absence of the amorphous phase is attributed to the reverse transformation due to the higher residual temperature in the 8.5 GPa sample. Since the Cmcm phase is the equilibrium high pressure phase of such materials, the results can be interpreted on the three level free energy diagram. The comparison of these results with those reported under static pressure will also be presented.

  12. Critical behavior of the quasi-two-dimensional weak itinerant ferromagnet trigonal chromium telluride Cr0.62Te

    Science.gov (United States)

    Liu, Yu; Petrovic, C.

    2017-10-01

    The critical properties of flux-grown single-crystalline quasi-two-dimensional weak itinerant ferromagnet Cr0.62Te were investigated by bulk dc magnetization around the paramagnetic to ferromagnetic phase transition. Critical exponents β =0.315 (7 ) with a critical temperature Tc=230.6 (3 ) K and γ =1.81 (2 ) with Tc=229.1 (1 ) K are obtained by the Kouvel-Fisher method whereas δ =6.35 (4 ) is obtained by a critical isotherm analysis at Tc=230 K. With these obtained exponents, the magnetization-field-temperature curves collapse into two independent curves following a single scaling equation M | T/-Tc Tc|-β=f±(H | T/-Tc Tc|-βδ) around Tc, suggesting the reliability of the obtained exponents. Additionally, the determined exponents of Cr0.62Te exhibit an Ising-like behavior with a change from short-range order to long-range order in the nature of magnetic interaction and with an extension from two to three dimensions on cooling through Tc.

  13. On the Riemann theta function of a trigonal curve and solutions of the Boussinesq and KP equations

    Science.gov (United States)

    Matveev, V. B.; Smirnov, A. O.

    1987-07-01

    Recently, considerable progress has been made in understanding the nature of the algebro-geometrical superposition principles for the solutions of nonlinear completely integrable evolution equations, and mainly for the equations related to hyperelliptic Riemann surfaces. Here we find such a superposition formula for particular real solutions of the KP and Boussinesq equations related to the nonhyperelliptic curve ω4 = (λ - E 1) (λ - E 2) (λ - E 3) (λ - E 4). It is shown that the associated Riemann theta function may be decomposed into a sum containing two terms, each term being the product of three one-dimensional theta functions. The space and time variables of the KP and Boussinesq equations enter into the arguments of these one-dimensional theta functions in a linear way.

  14. Novel class of heterometallic cubane and boride clusters containing heavier group 16 elements.

    Science.gov (United States)

    Thakur, Arunabha; Sao, Soumik; Ramkumar, V; Ghosh, Sundargopal

    2012-08-06

    Thermolysis of an in situ generated intermediate, produced from the reaction of [Cp*MoCl(4)] (Cp* = η(5)-C(5)Me(5)) and [LiBH(4).THF], with excess Te powder yielded isomeric [(Cp*Mo)(2)B(4)TeH(5)Cl] (2 and 3), [(Cp*Mo)(2)B(4)(μ(3)-OEt)TeH(3)Cl] (4), and [(Cp*Mo)(4)B(4)H(4)(μ(4)-BH)(3)] (5). Cluster 4 is a notable example of a dimolybdaoxatelluraborane cluster where both oxygen and tellurium are contiguously bound to molybdenum and boron. Cluster 5 represents an unprecedented metal-rich metallaborane cluster with a cubane core. The dimolybdaheteroborane 2 was found to be very reactive toward metal carbonyl compounds, and as a result, mild pyrolysis of 2 with [Fe(2)(CO)(9)] yielded distorted cubane cluster [(Cp*Mo)(2)(BH)(4)(μ(3)-Te){Fe(CO)(3)}] (6) and with [Co(2)(CO)(8)] produced the bicapped pentagonal bipyramid [(Cp*MoCo)(2)B(3)H(2)(μ(3)-Te)(μ-CO){Co(3)(CO)(6)}] (7) and pentacapped trigonal prism [(Cp*MoCo)(2)B(3)H(2)(μ(3)-Te)(μ-CO)(4){Co(6)(CO)(8)}] (8). The geometry of 8 is an example of a heterometallic boride cluster in which five Co and one Mo atom define a trigonal prismatic framework. The resultant trigonal prism core is in turn capped by two boron, one Te, and one Co atom. In the pentacapped trigonal prism unit of 8, one of the boron atoms is completely encapsulated and bonded to one molybdenum, one boron, and five cobalt atoms. All the new compounds have been characterized in solution by IR, (1)H, (11)B, and (13)C NMR spectroscopy, and the structural types were unambiguously established by crystallographic analysis of 2 and 4-8.

  15. A new benzodiazepine molecule and its interactions with diorganotin(IV)chlorides

    Science.gov (United States)

    Garoufis, Achilleas; Kitos, Alexandros A.; Lymperopoulou, Smaragda; Nastopoulos, Vasileios; Plakatouras, John C.; Ypsilantis, Konstantinos

    2015-01-01

    2-Methyl-2,4-di-thiophen-2‧,2″-yl-2,3-dihydro-1H-benzo[b][1,4]diazepine (L) has been synthesized through condensation of phenylene-1,2-diamine and 2-acetylthiophene, and its reactions with dialkyltin(IV)dichlorides have been studied. Two salts formulated as (LH)[R2SnCl3] (R = Et, 1; R = Me, 2) have been isolated. L and 1 were structurally characterized. The conformation of the benzodiazepine L, changes in 1 due to H-bonds formation. [Et2SnCl3]- is one of the rare examples of five coordinated tin(IV) species and has distorted trigonal bipyramidal geometry. H-bonding interactions, in 1, lead to the formation of supramolecular helices.

  16. Zn(1.86)Cd(0.14)(OH)VO(4).

    Science.gov (United States)

    Dorđević, Tamara; Stojanović, Jovica; Karanović, Ljiljana

    2010-11-10

    The title compound, dizinc cadmium hydroxide tetraoxido-vanadate, Zn(1.86)Cd(0.14)(OH)VO(4), was prepared under low-temperature hydro-thermal conditions. It is isostructural with Zn(2)(OH)VO(4) and Cu(2)(OH)VO(4). In the crystal structure, chains of edge-sharing [ZnO(6)] octahedra are inter-connected by VO(4) tetra-hedra (site symmetries of both V atoms and their coordination polyhedra are .m.) to form a three-dimensional [Zn(OH)VO(4)](2-) framework with channels occupied by Zn and Zn/Cd cations adopting trigonal-bipyramidal and distorted octa-hedral coordinations, respectively. Zn(1.86)Cd(0.14)(OH)VO(4) is topologically related to adamite-type phases, and descloizite- and tsumcorite-type structures.

  17. Acetonitrile-bis-(2,9-dimethyl-1,10-phen-an-throline)copper(II) bis-(tetra-fluorido-borate).

    Science.gov (United States)

    Watton, Stephen P

    2010-10-23

    The title compound, [Cu(CH(3)CN)(C(12)H(12)N(2))(2)](BF(4))(2), crystallizes with two copper-containing cations and four tetra-fluoro-borate anions in the asymmetric unit. The structure represents a second crystal form of the salt, the first being an acetonitrile solvate [Watton (2009 ▶). Acta Cryst. E65, m585-m586]. The complex cation has a distorted trigonal-bipyramidal geometry, whereas the previous structure exhibits a distorted square-pyramidal geometry. One of the four BF(4) (-) counter-ions is disordered, with a refined site occupancy of 0.8615 (17):0.1385 (17).

  18. Bis(μ2-pyridine-2-carboxamide oximatobis[(pyridine-2-carboxamide oximezinc] dinitrate

    Directory of Open Access Journals (Sweden)

    Xiao-Hui Deng

    2011-09-01

    Full Text Available In the title dinuclear compound, [Zn2(C6H6N3O2(C6H7N3O2](NO32, the ZnII cation is N,N′-chelated by one pyridine-2-carboxamide oximate anion and one pyridine-2-carboxamide oxime molecule, and is further bridged by an oxime O atom from the adjacent pyridine-2-carboxamide oximate anion, forming a distorted trigonal bipyramidal coordination. Two pyridine-2-carboxamide oximate anions bridge two ZnII cations to form the centrosymmetric dinuclear molecule. Extensive O—H...O, N—H...O and O—H...N hydrogen bonds are present in the crystal structure.

  19. The lanthanum(III molybdate(VI La4Mo7O27

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    Petra Becker

    2009-08-01

    Full Text Available Crystals of the orthorhombic phase La4Mo7O27 (lanthanum molybdenum oxide were obtained from a non-stoichiometric melt in the pseudo-ternary system La2O3–MoO3–B2O3. In the crystal structure, distorted square-antiprismatic [LaO8] and monocapped square-antiprismatic [LaO9] polyhedra are connected via common edges and faces into chains along [010]. These chains are arranged in layers that alternate with layers of [MoO4] and [MoO5] polyhedra parallel to (001. In the molybdate layers, a distorted [MoO5] trigonal bipyramid is axially connected to two [MoO4] tetrahedra, forming a [Mo3O11] unit.

  20. Aqua(2,9-dimethyl-1,10-phenanthroline-κ2N,N′bis(3-hydroxybenzoato-κOmanganese(II–2,9-dimethyl-1,10-phenanthroline–water (1/1/1

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    Linyu Jin

    2009-08-01

    Full Text Available In the title compound, [Mn(C7H5O32(C14H12N2(H2O]·C14H12N2·H2O, the MnII ion is coordinated by a bidentate 2,9-dimethyl-1,10-phenanthroline (dmphen ligand, two monodentate 3-hydroxybenzoate anions (3-HBA and one water molecule in a distorted trigonal-bipyramidal environment. An uncoordinated dmphen and an uncoordinated water molecule cocrystallized with each complex molecule. Intra- and intermolecular O—H...N and O—H...O hydrogen bonds are also present between the coordinated 3-HBA and water molecules and the uncoordinated dmphen and water molecules in the crystal. The packing of the structure is further stabilized by π–π stacking interactions involving dmphen molecules, with a centroid–centroid separation of 3.705 (3 Å.

  1. Exchanging conformations of a hydroformylation catalyst structurally characterized using two-dimensional vibrational spectroscopy.

    Science.gov (United States)

    Panman, Matthijs R; Vos, Jannie; Bocokić, Vladica; Bellini, Rosalba; de Bruin, Bas; Reek, Joost H N; Woutersen, Sander

    2013-12-16

    Catalytic transition-metal complexes often occur in several conformations that exchange rapidly (trigonal-bipyramidal structure. On the basis of complementary density functional calculations, we ascribe this effect to attractive van der Waals interaction between the CO and the xantphos ligand.

  2. Low-dimensional compounds containing cyano groups. X. (Dicyanamido-kappaN1)bis(1,10-phenanthroline-kappa2N,N')copper(II) perchlorate.

    Science.gov (United States)

    Burcák, Milan; Potocnák, Ivan; Baran, Peter; Jäger, Lothar

    2004-12-01

    The title compound, [Cu(C(2)N(3))(C(12)H(8)N(2))(2)]ClO(4), represents a relatively rare class of compounds with dicyanamide coordinated in a monodentate manner. The structure is formed by the [Cu{N(CN)(2)}(phen)(2)](+) complex cation (phen is 1,10-phenanthroline) and an uncoordinated ClO(4)(-) anion. The Cu atom is five-coordinate, with a slightly distorted trigonal-bipyramidal environment. The dicyanamide ligand is coordinated through one nitrile N atom in the equatorial plane, at a distance of 2.033 (6) angstroms from the metal. The two axial Cu-N distances are similar [mean 1.999 (4) angstroms] and are substantially shorter than the remaining two equatorial Cu-N bonds [mean 2.087 (1) angstroms].

  3. Cryo-Trapping the Distorted Octahedral Reaction Intermediate of Manganese Superoxide Dismutase

    Science.gov (United States)

    Borgstahl, Gloria; Snell, Edward H.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Superoxide dismutase protects organisms from potentially damaging oxygen radicals by catalyzing the disproportion of superoxide to oxygen and hydrogen peroxide. We report the use of cryogenic temperatures to kinetically trap the 6th ligand bound to the active site of manganese superoxide dismutase. Using cryocrystallography and synchrotron radiation, we describe at 1.55A resolution the six-coordinate, distorted octahedral geometry assumed by the active site during catalysis and compare it to the room temperature, five-coordinate trigonal-bipyramidal active site. Gateway residues Tyr34, His30 and a tightly bound water molecule are implicated in closing off the active site and blocking the escape route of superoxide during dismutation.

  4. Synthesis, Spectral, and In Vitro Antibacterial Studies of Organosilicon(IV) Complexes with Schiff Bases Derived from Amino Acids.

    Science.gov (United States)

    Singh, Har Lal; Singh, Jangbhadur; Mukherjee, A

    2013-01-01

    The present work stems from our interest in the synthesis, characterization, and antibacterial evaluation of organosilicon(IV) complexes of a class of amino-acid-based Schiff base which have been prepared by the interaction of ethoxytrimethylsilane with the Schiff bases (N OH) in 1 : 1 molar ratio. These complexes have been characterized by elemental analysis, molar conductance, and spectroscopic studies including electronic IR and NMR ((1)H, (13)C, and (29)Si) spectroscopy. The analytical and spectral data suggest trigonal bipyramidal geometry around the silicon atom in the resulting complexes. The ligands and their organosilicon complexes have also been evaluated for in vitro antimicrobial activity against bacteria (Bacillus cereus, Nocardia spp., E. aerogenes, Escherichia coli, Klebsiella spp., and Staphylococcus spp.). The complexes were found to be more potent as compared to the ligands.

  5. O2CC6H4C6H4CO2(SnPh32∙4H2O AND HO2CC6H4C6H4CO2SnBu2Cl: SYNTHESIS AND INFRARED STUDY

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    ABDOU MBAYE

    2015-02-01

    Full Text Available When the diphenic acid HO2CC6H4C6H4CO2H is allowed to react with SnBu2Cl2 or SnPh3OH, HO2CC6H4C6H4CO2. SnBu2Cl (A and O2CC6H4C6H4CO2(SnPh32∙4H2O(B were obtained and characterized by infrared spectroscopy. The structures are an infinite chain or an oligomer, the diphenic anion being a monodentate or a monochelating ligand. The environment around the tin centers is trigonal bipyramidal or octahedral.

  6. Synthesis, Structure and Antitumor Activity of Dibutyltin Oxide Complexes with 5-Fluorouracil Derivatives. Crystal Structure of [(5-Fluorouracil-1-CH2CH2COOSn(n-Bu 2]4O2

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    Zhan Shi

    2001-07-01

    Full Text Available Dibutyltin (IV oxide complex reacts with the fluorouracil compounds 5-fluorouracil-1-propanonic or 5-fluorouracil-1-acetic acid (Fu to give the complexes [(5-Fu-1-(CH2nCOOSn(n-Bu2]4O2 (I, n=2; II, n=1 which were characterized by IR and 1H-NMR. The crystal structure of complex I shows that the molecular is a dimer, in which two [(5-Fu-1-CH2CH2COOSn(n-Bu2]2O units are linked by a bridging oxygen atom, and the tin atoms adopt distorted trigonal bipyramids via two carbons from a dibutyl moiety and three oxygen atoms from 5-Fu and bridging oxygen. These complexes have potential anti-tumour activity: in vitro tests showed that complexes I and II exhibit high cytotoxicity against OVCAR-3 and PC-14.

  7. HREM studies of phases based on α-U 3O 8-type layers in the Cu 2OTa 2O 5 system

    Science.gov (United States)

    Jahnberg, Lena; Sundberg, Margareta

    1992-10-01

    The high-resolution electron microscopy (HREM) technique was used to characterize phases in the Cu 2OTa 2O 5 system. The structures are closely related. They contain edge-sharing pentagonal TaO 7 bipyramids, forming layers of α-U 3O 8 type. These layers are either single or double, the latter linked by apex oxygens. The layers are interleaved by octahedral Ta sites and linearly coordinated Cu positions so that a three-dimensional network is formed. The symmetry is hexagonal (or trigonal). Varying sequences of single (S) and double (D) layers give different c-axis lengths. The phases Cu 5Ta 11O 30 and Cu 3Ta 7O 19 are well ordered, with SDSD and DD sequences, respectively. Other ordered sequences, (SS) in "Cu 2Ta 4O 11" and (SDSSDS) in "Cu 7Ta 15O 41," were also observed. Defects and disorder sometimes occur.

  8. Crystal structure of di-μ2-chlorido-bis-[(1-aza-4-azoniabi-cyclo-[2.2.2]octane-κN (1))di-chlorido-dicadmium].

    Science.gov (United States)

    Yan, Jing-Jing; Pan, Qi-Jian; Chen, Li-Zhuang

    2015-12-01

    In the structure of the binuclear title compound, [Cd2(C6H13N2)2Cl6], two Cd(II) atoms are bridged by two Cl(-) ligands, defining a centrosymmetric Cd2Cl2 motif. Each metal cation is additionally coordinated by two Cl(-) ligands and the N atom of a protonated 1,4-di-aza-bicyclo-[2.2.2]octane (H-DABCO)(+) ligand, leading to an overall trigonal-bipyramidal coordination environment with one of the bridging Cl(-) ligands and the N atom at the apical sites. In the crystal, the neutral dimers are linked via N-H⋯Cl hydrogen bonds, forming a two-dimensional network expanding parallel to (100).

  9. Syntheses, Crystal Structures and Thermal Behaviors of Two Supramolecular Salamo-Type Cobalt(II and Zinc(II Complexes

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    Gang Li

    2017-07-01

    Full Text Available This paper reports the syntheses of two new complexes, [Co(L1(H2O2] (1 and [{Zn(L2(μ-OAcZn(n-PrOH}2] (2, from asymmetric halogen-substituted Salamo-type ligands H2L1 and H3L2, respectively. Investigation of the crystal structure of complex 1 reveals that the complex includes one Co(II ion, one (L12− unit and two coordinated water molecules. Complex 1 shows slightly distorted octahedral coordination geometry, forming an infinite 2D supramolecular structure by intermolecular hydrogen bond and π–π stacking interactions. Complex 2 contains four Zn(IIions, two completely deprotonated (L23− moieties, two coordinated μ-OAc− ions and n-propanol molecules. The Zn(II ions in complex 2 display slightly distorted trigonal bipyramidal or square pyramidal geometries.

  10. 1.2.2.Synthesis, crystal structure and in vitro anti-tumor activity of dibutyltin complex of 2,4-dichloro-5-fluorobenzoic acid

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    Ming Li, Liqin Wang, Zhenlei Zhang, Yue Xin, Laijin Tian*

    2014-04-01

    Full Text Available The dibutyltin complex of 2,4-dichloro-5- fluorobenzoic acid, [(2,4-Cl2 -5-FC6 H2 C(OOSnBu2 2 O]2 (Bu = CH2 CH2 CH2 CH3 (1 , has been synthesized and characterized by elemental analysis, FT-IR, 119 Sn NMR spectroscopy, and Xray single crystal diffraction. Compound 1 is a centrosymmetric dimmer with two distinct types of carboxylate moieties and tin atoms with distorted trigonal bipyramidal geometries. The in vitro  anti-tumor activity of 1 against two human tumor cell lines was found to be higher than that for cis-platin [cis diaminedichloroplatinum( II] used clinically. Supporting information : FT-IR, 119 Sn NMR, X-Ray, Proliferation inhibitory rate, Cif file.

  11. 2.2.2. Synthesis, crystal structure and biological activity of triphenyltin 4-acetylphenolate

    Directory of Open Access Journals (Sweden)

    Zhikun Liua, Yunsai Donga, Xiaoliang Zhengb, You Yua, Laijin Tiana,*

    2015-03-01

    Full Text Available Abs t ract : Tr i ph en yl t in 4-a cet yl ph en ol at e, 4- CH3COC6H4OSnPh3 (1, has been synthesized and characterized by elemental analysis, IR, NMR (1H, 13C and 119Sn spectra, and X-ray single crystal diffraction. Compound  1 possesses a trans-C3SnO2 trigonal bipyramidal geometry with the axial positions occupied by the phenolate oxygen and carbonyl oxygen of an adjacent molecule and form an one-dimensional infinite chain. Bioassay results have shown that the compound has good in vitro anti-bacterial and anti-tumor activities. Supporting information: X-Ray (CIF file

  12. Technetium complexes with arylselenolato and aryltellurolato ligands.

    Science.gov (United States)

    Noschang Cabral, B; Kirsten, L; Hagenbach, A; Piquini, P C; Patzschke, M; Lang, E Schulz; Abram, U

    2017-07-18

    Reactions of (NBu4)[TcOCl4] or [TcCl3(PPh3)2(CH3CN)] with in situ-prepared lithium arylselenolates and -tellurolates give (NBu4)[Tc(V)O(ArE)4] (E = Se, Te; Ar = phenyl) and [Tc(III)(ArE)3(PPh3)(CH3CN)] (E = Se, Te; Ar = phenyl, 2,6-Me2phenyl, mesityl) complexes, respectively. The products contain square-pyramidal (Tc(V) compounds) and trigonal bipyramidal (Tc(III) complexes) coordinated technetium atoms. Density functional theory calculations indicate that the Tc-chalcogen bonds in the Tc(III) compounds have a greater bond order than those in the Tc(V) compounds.

  13. SYNTHESIS AND INFRARED STUDY OF SOME NEW MOLYBDATO AND HYDROGENOMOLYBDATO ADDUCTS AND COMPLEXES OF COBALT, ZINC, ANTIMONY AND CADMIUM CHLORIDES

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    SERIGNE FALLOU POUYE

    2014-01-01

    Full Text Available Five new molybdato (four and hydrogenomolybdato (one adducts and complexes have been synthesized and studied by infrared spectroscopy. The suggested structures are all discrete, the molybdate anion behaving as a trichelating, a monochelating, a bridging, a tetrachelating and a bichelating ligand. The environment around Zn, Co, Cd is tetrahedral or trigonal bipyramidal also for Zn - while being octahedral for Sb. The Cd pentanuclear adduct has a two metallic components structure, a tetranuclear anionic one with a tetrachelating molybdate, the second being a neutral dehydrated adduct component. The suggested structure for the hydrogenomolybdato adduct is discrete, the hydrogenomolybdate being present as a hydrogen bonded dimer behaves as a bridging bidentate ligand. The water molecules can be considered as a coordinating ligand or lattice. When secondary interactions through hydrogen bonds involving the water molecules are considered supramolecular architectures are obtained.

  14. Aquabis(3′-hydroxy-2,2′-bipyridine-3-olato-κ2N,N′zinc(II

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    Chao Hou

    2008-09-01

    Full Text Available In the title complex, [Zn(C10H7N2O22(H2O], the ZnII ion and water O atom are located on a crystallographic twofold rotation axis and the metal atom assumes a distorted trigonal-bipyramidal ZnN4O coordination geometry. An intramolecular O—H...O hydrogen bond occurs within the ligand and intermolecular O—H...O hydrogen bonds involving the water molecule result in a sheet structure in the crystal structure. In addition, a short C—O...π contact between the O atom of the deprotonated hydroxyl group and a nearby pyridine ring [O...Cg = 3.977 (2 Å, where Cg is the centroid of the pyridine ring] is observed.

  15. Octabutylbis[μ2-4-(diethylaminobenzoato-κ2O:O′]bis[4-(diethylaminobenzoato-κO]di-μ3-oxido-tetratin(IV

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    Yip-Foo Win

    2011-08-01

    Full Text Available The asymmetric unit of the title complex, [Sn4(C4H98(C11H14NO24O2], consists of two crystallographically independent half-molecules. The other halves are generated by crystallographic inversion centers. In each tetranuclear molecule, both of the two independent Sn atoms are five-coordinated, with distorted trigonal–bipyramidal SnC2O3 geometries. One Sn atom is coordinated by two butyl groups, one O atom of the benzoate anion and two bridging O atoms, whereas the other Sn atom is coordinated by two butyl groups, two O atoms of the benzoate anions and a bridging O atom. All the butyl groups are equatorial with respect to the SnO3 trigonal plane. Weak intramolecular C—H...O hydrogen bonds stabilize the molecular structures. In one molecule, two of the butyl groups and the bridging benzoate anion are each disordered over two positions.

  16. Chloridobis{2-[(dimethylaminomethyl]phenyl}antimony(III

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    Marian Olaru

    2009-11-01

    Full Text Available In the title compound, [Sb(C9H12N2Cl], the Sb atom adopts a Ψ-trigonal-bipyramidal geometry. The two 2-[(dimethylaminomethyl]phenyl ligands are coordinated asymmetrically to the Sb atom. The carbon atoms of one of the ligands are disordered over sets of sites with equal occupancy, resulting in two conformational isomers in the crystal. The Sb—C and Sb—N distances in the ordered ligand are: 2.153 (4 and 3.326 (5 Å, respectively. The corresponding distances in the disordered ligand are: 2.103 (5/2.188 (5 and 2.454 (3 Å, respectively. The structure displays intramolecular C—H...Cl hydrogen bonding.

  17. A novel iron complex containing an N,O-type bidentate oxazoline ligand: Synthesis, X-ray studies, DFT calculations and catalytic activity

    Science.gov (United States)

    Amini, Mojtaba; Arab, Ali; Derakhshandeh, Parviz Gohari; Bagherzadeh, Mojtaba; Ellern, Arkady; Woo, L. Keith

    2014-12-01

    A five-coordinated Fe(III) complex with the distorted trigonal bipyramidal configuration was synthesized by reactions of FeCl3ṡ6H2O and 2-(2";-hydroxyphenyl)oxazoline (Hphox) as a bidentate Osbnd N donor oxazoline ligand. Complex [Fe(phox)2Cl] was fully characterized, including by single-crystal X-ray structure analysis. DFT calculations were accompanied with experimental results in order to obtain a deeper insight into the electronic structure and vibrational normal modes of complex. Oxidation of sulfides to sulfoxides in one-step was conducted by this complex as catalyst using urea hydrogen peroxide (UHP) in mixture of CH2Cl2/CH3OH (1:1) under air at room temperature. The results show that using this system in oxidation of sulfides, sulfoxides are obtained as the main products, together with variable amounts of sulfones (⩽13%), depending on the nature of the substrate.

  18. Synthesis of endo,endo-2,5-bis((diphenylphosphino)methyl)bicyclo(2. 2. 1)heptane, a chelating diphosphine with a natural bite angle of 120 degree

    Energy Technology Data Exchange (ETDEWEB)

    Casey, C.P.; Whiteker, G.T. (Univ. of Wisconsin, Madison (United States))

    1990-02-16

    One of the key intermediates in rhodium-catalyzed hydroformylation reactions is a trigonal-bipyramidal rhodium diphosphine species. The two phosphines in (R{sub 3}P){sub 2}(CO){sub 2}RhH have the possibility of occupying two axial, two equatorial, or one axial and one equatorial position. Use of chelating ligands such as DIPHOS, which has a preferred bite angle (P-M-P) of about 90{degree} allows study of locked axial, equatorial diphosphine catalysts. Because of the authors' interest in hydroformylation, they have initiated a program to design and synthesize chelating diphosphines which have a constrained bite angle near 120{degree} for selective diequatorial coordination. Here they describe the synthesis and characterization of the racemic diphosphine.

  19. Aquatrichlorido(1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane-κN4copper(II monohydrate

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    Qinqin Zhou

    2012-05-01

    Full Text Available The asymmetric unit of the title compound, [CuCl3(C8H14N3(H2O]·H2O, comprises a neutral complex and a molecule of free water. The complex contains coordinated CuII ions, with Cu—Cl distances ranging from 2.3471 (8 to 2.4011 (8 Å, and with Cu—N and Cu—O distances of 2.0775 (19 and 2.0048 (18 Å, respectively. The resulting coordination polyhedron is a trigonal bipyramid with the Cl atoms in the equatorial plane. In the crystal, O—H...Cl and O—H...O hydrogen bonds link the molecules into a three-dimensional structure.

  20. Poly[bis(N,N-dimethylformamide(μ-formato(μ5-4-oxidoisophthalatodizinc(II

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    Young Ho Jhon

    2009-08-01

    Full Text Available The title compound, [Zn2(CHO2(C8H3O5(C3H7NO2]n, is a three-dimensional metal–organic framework, of which two independent ZnII atoms (denoted Zn1 and Zn2 are linked by both 4-oxidoisophthalate and formate bridging ligands. The 4-oxidoisophthalate ligands link two Zn1-type and three Zn2-type atoms, forming a corrugated sheet roughly parallel to the ac plane. The formate ions join two neighboring sheets along the b axis, forming a three-dimensional network. Two independent dimethylformamide ligands are coordinated to separate ZnII atoms and fill the voids provided by the framework. Both types of ZnII atoms have a distorted trigonal-bipyramidal coordination geometry.

  1. Poly[bis-(N,N-dimethyl-formamide)(μ-formato)(μ(5)-4-oxidoisophthalato)dizinc(II)].

    Science.gov (United States)

    Jhon, Young Ho; Kim, Jaheon

    2009-07-25

    The title compound, [Zn(2)(CHO(2))(C(8)H(3)O(5))(C(3)H(7)NO)(2)](n), is a three-dimensional metal-organic framework, of which two independent Zn(II) atoms (denoted Zn1 and Zn2) are linked by both 4-oxidoisophthalate and formate bridging ligands. The 4-oxidoisophthalate ligands link two Zn1-type and three Zn2-type atoms, forming a corrugated sheet roughly parallel to the ac plane. The formate ions join two neighboring sheets along the b axis, forming a three-dimensional network. Two independent dimethylformamide ligands are coordinated to separate Zn(II) atoms and fill the voids provided by the framework. Both types of Zn(II) atoms have a distorted trigonal-bipyramidal coordination geometry.

  2. Crystal structure of hexa­kis­(dmpu)-di-μ2-hydroxido-dialuminium tetraiodide dmpu tetra­solvate [dmpu is 1,3-di­methyl­tetra­hydro­pyrimidin-2(1H)-one]: a centrosymmetric dinuclear aluminium complex containing AlO5 polyhedra

    OpenAIRE

    Lundberg, Daniel; Lyczko, Krzysztof

    2015-01-01

    The structure of the title compound, [Al2(OH)2(C6H12N2O)6]I4·4C6H12N2O (systematic name: di-μ2-hydroxido-bis­{tris­[1,3-di­methyl­tetra­hydro­pyrimidin-2(1H)-one-κO]aluminium} tetra­iodide 1,3-di­methyl­tetra­hydro­pyrimidin-2(1H)-one tetra­solvate), is composed of two Al(C6H12N2O)3 moieties linked into a centrosymmetric dinuclear unit by a pair of bridging hydroxide ions. The aluminium cations show a distorted trigonal bipyramidal AlO5 coordination environment formed only by monodentate liga...

  3. Synthesis of Two New Group 13 Benzoato-Chloro Complexes: A Structural Study of Gallium and Indium Chelating Carboxylates

    Science.gov (United States)

    Duraj, Stan A.; Hepp, Aloysius F.; Woloszynek, Robert; Protasiewicz, John D.; Dequeant, Michael; Ren, Tong

    2010-01-01

    Two new heteroleptic chelated-benzoato gallium (III) and indium (III) complexes have been prepared and structurally characterized. The molecular structures of [GaCl2(4-Mepy)2(O2CPh)]4-Mepy (1) and [InCl(4-Mepy)2(O2CPh)2]4-Mepy (2) have been determined by single-crystal x-ray diffraction. The gallium compound (1) is a distorted octahedron with cis-chloride ligands co-planar with the chelating benzoate and the 4-methylpyridines trans to each other. This is the first example of a Ga(III) structure with a chelating benzoate. The indium compound (2) is a distorted pentagonal bipyramid with two chelating benzoates, one 4-methylpyridine in the plane and a chloride trans to the other 4-methylpyridine. The indium bis-benzoate is an unusual example of a seven-coordinate structure with classical ligands. Both complexes, which due to the chelates, could also be described as pseudo-trigonal bipyramidal, include a three-bladed motif with three roughly parallel aromatic rings that along with a solvent of crystallization and electron-withdrawing chloride ligand(s) stabilize the solid-state structures.

  4. Crystallographic, DFT and docking (cathepsin B) studies on an organotellurium(IV) compound

    Energy Technology Data Exchange (ETDEWEB)

    Caracelli, Ignez; Maganhi, Stella H. [Univ. Federal de Sao Carlos (Brazil). BioMat; Zukerman-Schpector, Julio; Sousa Madureira, Lucas [Univ. Federal de Sao Carlos (Brazil). Lab. de Cristalografia, Estereodinamica e Modelagem Molecular; Stefani, Helio A. [Sao Paulo Univ. (Brazil). Dept. de Farmacia; Guadagnin, Rafael C. [Univ. Federal de Sao Paulo, Diadema (Brazil). Inst. e Ciencias Mabientais, Quimicas e Farmaceuticas; Tiekink, Edward R.T. [Sunway Univ., Selangor Darul Ehsan (Malaysia). Centre for Crystalline Materials

    2016-08-01

    Some biologically active organotellurium compounds exhibit inhibitory potency against cathepsin B. In this study, an alkyl derivative, viz. [CH{sub 3}(CH{sub 2}){sub 2}C(I)=C(H)](nBu)TeI{sub 2}, 1, has been structurally characterised by X-ray crystallography and shown to be coordinated within a C{sub 2}I{sub 2} donor set. When the stereochemically active lone pair of electrons is taken into account, a distorted trigonal bipyramidal geometry results with the iodide atoms in axial positions. Both intra- and inter-molecular Te..I interactions are also noted. If all interactions are considered, the coordination geometry is based on a Ψ-pentagonal bipyramidal geometry. An unusual feature of the structure is the curving of the functionalised C{sub 5} chain. This feature has been explored by DFT methods and shown to arise as a result of close C-H..I interactions. A docking study (cathepsin B) was performed to understand the inhibition mechanism and to compare the new results with previous observations. Notably, 1 has the same pose exhibited by analogous biologically active compounds with aryl groups. Thus, the present study suggests that (alkyl){sub 2}TeX{sub 2} compounds should also be evaluated for biological activity.

  5. Chloro(histamine)(1,10-phenanthroline)copper(II) chloride monohydrate.

    Science.gov (United States)

    Bivián-Castro, Egla Y; Bernès, Sylvain; Escalante, Jaime; Mendoza-Díaz, Guillermo

    2004-05-01

    In the cationic complex present in the title compound, chloro[2-(4-imidazolyl-kappaN(1))ethylamine-kappaN](1,10-phenanthroline-kappa(2)N,N')copper(II) chloride monohydrate, [CuCl(C(5)H(9)N(3))(C(12)H(8)N(2))]Cl.H(2)O, the metal centre adopts a five-coordinate geometry, ligated by the two phenanthroline N atoms, two amine N atoms of the histamine ligand (one aliphatic and one from the imidazole ring) and a chloro ligand. The geometry around the Cu atom is a distorted compressed trigonal bipyramid, with one phenanthroline N and one imidazole N atom in the axial positions, and the other phenanthroline N atom, the histamine amine N atom and the chloro ligand in the equatorial positions. The structure includes an uncoordinated water molecule, and a Cl(-) ion to complete the charge. The water molecule is hydrogen bonded to both Cl(-) ions (coordinated and uncoordinated), and exhibits a close Cu.H contact in the equatorial plane of the bipyramid.

  6. Synthesis, crystal structure and reactivity of copper(II) complexes of tetradentate N2S2 donor ligands

    Science.gov (United States)

    Sarkar, Sandipan; Paul, Hena; Drew, Michael G. B.; Zangrando, Ennio; Chattopadhyay, Pabitra

    2009-09-01

    Two new hexa-coordinated mononuclear copper(II) complexes of two ligands L 1 and L 2 containing NSSN donor sets formulated as [Cu(L)(H 2O) 2](NO 3) 2 [ 1a, L = 1,2-bis(2-pyridylmethylthio)ethane (L 1), 1b L = 1,3-bis(2-pyridyl-methylthio)propane (L 2)] were synthesized and characterized by physico-chemical and spectroscopic methods. In 1a the single crystal X-ray crystallography analysis showed a distorted octahedral geometry about copper(II) ion. The crystal packing evidences pairs of complexes arranged about a center of symmetry and connected through a H-bond occurring between aquo ligands and nitrate anions. On reaction with chloride and pseudohalides (N 3- and SCN -), in acetonitrile at ambient temperature, complexes 1 changed to monocationic penta-coordinated mononuclear copper(II) species formulated as [Cu(L)(Cl)]NO 3 ( 2), [Cu(L)(N 3)]NO 3 ( 3), and [Cu(L)(SCN)]NO 3 ( 4). These copper(II) complexes have been isolated in pure form from the reaction mixtures and characterized by physico-chemical and spectroscopic tools. The solid-state structure of 2a, established by X-ray crystallography, shows a trigonal bipyramidal geometry about the metal ion with a trigonality index ( τ) of 0.561.

  7. Synthesis, spectra and crystal structure of 2-(?[3-(methyl?3-[(2-hydroxybenzylidene)amino]propyl? amino)propyl]imino?methyl)phenol copper(II) complex

    Science.gov (United States)

    Yilmaz, Veysel T.; Degirmencioglu, Ismail; Andac, Omer; Karabocek, Serdar; Slawin, Alexandra M. Z.

    2003-06-01

    A copper(II) complex, [Cu(salenN3], [salenN3H2=2-({[3-(methyl{3-[(2-hydroxybenzylidene)amino]propyl}amino)propyl]imino}methyl)phenol] was synthesized and characterized by elemental analyses, FTIR spectra and single crystal X-ray diffraction. The complex crystallizes in the monoclinic space group P21/ c with a=6.877(3), b=14.109(6), c=20.106(8) Å, β=92.231(14)°, V=1949.5(14) Å 3. The salen ligand loses two phenolic hydrogens being a dianion and coordinates to the copper(II) ion as a pentadentate ligand through its two O and three N atoms. The copper(II) complex is five-coordinate, lying between perfect square pyramidal and trigonal-bipyramidal extremes. Use of the structural index parameter ( τ) for five coordinate metal complexes indicated that the copper(II) complex exhibits a grater tendency toward trigonal-based-pyramidal geometry ( τ>0.5). The individual molecules in the crystal are held together by C-H⋯π and H⋯H interactions. The IR and electronic spectra of the complex were discussed in detail.

  8. Structural characterization of ZnCl{sub 2} modified tellurite based glasses

    Energy Technology Data Exchange (ETDEWEB)

    Dhankhar, Sunil, E-mail: dhankhar.sunil@gmail.com; Kundu, R. S.; Sunita [Guru Jambheshwar University of Science and Technology, Hisar (Haryana) – 125001 (India); Punia, R. [Indira Gandhi University, Meerpur, Rewari (Haryana) -123401 (India); Parmar, R. [Maharishi Dayanand University, Rohtak (Haryana)-124001 (India); Sanjay [Rawal Institute of Engineering and Technology, Faridabad (Haryana)-121004 (India); Kishore, N. [Central University of Haryana, Mahendergarh (Haryana)-123029 (India)

    2016-05-06

    Glass composition 70 TeO{sub 2}-(30-x) BaO – x ZnCl{sub 2}; x = 5, 10, 15, 20 and 25 have been prepared by rapid melt quenching technique under controlled atmospheric conditions. Amorphous nature of the samples was confirmed by x-ray diffractogram. The glass transition temperature (T{sub g}) has been determined using differential scanning calorimetry (DSC) and its value is observed to decrease with increase in ZnCl{sub 2} content. The peaks in the Raman and FTIR spectra have been estimated by deconvolutation of the spectra and each of deconvoluted spectra exhibits several peaks. IR and Raman spectra of the present glass system indicate that TeO{sub 2} exists as TeO{sub 3} trigonal pyramidal (tp), TeO{sub 4} trigonal bipyramidal (tbp) and TeO{sub 6} polyhedra structural units. With increase in zinc halide content, transformation of some of TeO{sub 4} structural units into TeO{sub 3} structural units is observed Increase in TeO{sub 3} structural units shows that non-bridging oxygen contribution increases which confirms the decrease in glass transition temperature.

  9. Tin( ii ) ketoacidoximates: synthesis, X-ray structures and processing to tin( ii ) oxide

    KAUST Repository

    Khanderi, Jayaprakash

    2015-10-21

    Tin(ii) ketoacidoximates of the type [HONCRCOO]Sn (R = Me 1, CHPh 2) and (MeONCMeCOO)Sn] NH·2HO 3 were synthesized by reacting pyruvate- and hydroxyl- or methoxylamine RONH (R = H, Me) with tin(ii) chloride dihydrate SnCl·2HO. The single crystal X-ray structure reveals that the geometry at the Sn atom is trigonal bipyramidal in 1, 2 and trigonal pyramidal in 3. Inter- or intramolecular hydrogen bonding is observed in 1-3. Thermogravimetric (TG) analysis shows that the decomposition of 1-3 to SnO occurs at ca. 160 °C. The evolved gas analysis during TG indicates complete loss of the oximato ligand in one step for 1 whereas a small organic residue is additionally removed at temperatures >400 °C for 2. Above 140 °C, [HONC(Me)COO]Sn (1) decomposes in air to spherical SnO particles of size 10-500 nm. Spin coating of 1 on Si or a glass substrate followed by heating at 200 °C results in a uniform film of SnO. The band gap of the produced SnO film and nanomaterial was determined by diffuse reflectance spectroscopy to be in the range of 3.0-3.3 eV. X-ray photoelectron spectroscopy indicates surface oxidation of the SnO film to SnO in ambient atmosphere.

  10. Gyroscope like molecules consisting of trigonal or square planar osmium rotators within three-spoked dibridgehead diphosphine stators: syntheses, substitution reactions, structures, and dynamic properties.

    Science.gov (United States)

    Fiedler, Tobias; Bhuvanesh, Nattamai; Hampel, Frank; Reibenspies, Joseph H; Gladysz, John A

    2016-04-28

    Reactions of (NH4)2OsX6 (X = Cl, Br) with CO and the phosphines P((CH2)mCH[double bond, length as m-dash]CH2)3 (m = 6, a; 7, b; 8, c) give cis,cis,trans-Os(CO)2(X)2(P((CH2)mCH[double bond, length as m-dash]CH2)3)2 (46-73%). These are treated with Grubbs' catalyst (7 mol%, 0.0010 M, C6H5Cl). Subsequent hydrogenations (PtO2) yield the gyroscope like complexes cis,cis,trans-Os(CO)2(X)2(P((CH2)n)3P) (n = 2m + 2; X = Cl, 6a-c; Br, 7a-c ; 5-31%) and the isomers cis,cis,trans-Os(CO)2(X)2(P(CH2)n-1CH2)((CH2)n)(P(CH2)n-1CH2) (X = Cl, 6'ac; Br, 7'a-c;12-51%) derived from a combination of interligand and intraligand metatheses. Reductions of 6a,c, 6’b, and 7'b with C8K under CO atmospheres afford trans-Os(CO)3(P((CH2)n)3P) (9a,c, 79-82%) and trans-Os(CO)3(P(CH2)15CH2)((CH2)16)(P(CH2)15CH2) (9’b, 53-84%). Reaction of 9a and CF3SO3H yields the cationic hydride complex mer,trans-[Os(H)(CO)3(P((CH2)14)3P)](+) CF3SO3(-) (9a-H(+) CF3SO3(-); quantitative by NMR). Preparative reactions of 9a,c or 9'b and [H(OEt2)2](+) BArf(-) (BArf(-) = B(3,5-C6H3(CF3)2)4(-)) afford 9a,c-H(+) BArf(-) (80%) or 9'b-H(+) BArf(-) (68%). Reactions of 6a, 6’b, and 7a with MeLi or PhLi give cis,cis,trans-Os(CO)2(Me)2(P((CH2)14)3P) (11a, 98%), cis,cis,trans-Os(CO)2(Me)2(P(CH2)15CH2)((CH2)16)(P(CH2)15CH2) (98%), and cis,cis,trans-Os(CO)2(Ph)2(P((CH2)14)3P) (12a, 58%). NMR data for 6a–c, 7a–c, 9a,c, 9a,c-H(+) X(-), and 11a indicate that rotation of the OsLy moieties is fast on the NMR time scale at room temperature. In contrast, the phenyl groups in 12a act as "brakes" and two sets of (13)C NMR signals are observed for the methylene chains (2 : 1). The crystal structures of 6a–c, 7b,c, 7’a, 9a, 9a -H(+) BArf(-), 11a, and 12a are analyzed with respect to OsLy rotation in solution and the solid state.

  11. Shock wave induced phase transitions from the trigonal phase to the coexisting amorphous and orthorhombic phases in α-FePO4

    Science.gov (United States)

    Joshi, K. D.; Suresh, N.; Jyoti, G.; Kulshreshtha, S. K.; Gupta, Satish C.; Sikka, S. K.

    1998-07-01

    The shock induced response of berlinite form of α-FePO4, which has been studied recently under static pressure, has been investigated in order to examine the effect of shear and high temperature on the process of amorphization in this material. The samples were shock loaded up to 8.5 GPa in a gas gun and after recovery were analyzed using x-ray diffraction (XRD) technique. The sample retrieved from 5.2 GPa revealed an irreversible phase transformation of some of the material to an amorphous and a crystalline orthorhombic structure (space group Cmcm), which are co-existing. The XRD pattern of the 8.5 GPa sample on the other hand displayed the presence of only the orthorhombic phase along with the ambient structure. The absence of the the amorphous phase is attributed to the reverse transformation due to the high residual temperature in the 8.5 GPa sample. Since the Cmcm phase is equilibrium high pressure phase of such materials, the results could be interpreted on the three level free energy diagram. The comparison of these results with those reported under static pressure is presented.

  12. Rational design and structural diversity of copper(II) complexes assembled from 3-sulfobenzoate and 2,2‧-bipyridine

    Science.gov (United States)

    Miao, Xiao-He; Zhu, Long-Guan

    2008-04-01

    Three new Cu II/3-sb/2,2'-bipy complexes, [Cu(2,2'-bipy) 2(3-sb)]·4 H 2O ( 1), {[Cu(2,2'-bipy)(3-sb)(H 2O) 2]·2. 5H 2O} n ( 2), and {[Cu(2,2'-bipy)(3-sb)(H 2O)]·2H 2O} n ( 3), in addition to the our previously reported {[Cu(2,2'-bipy)(3-sb)(H 2O)](H 2O)} n ( 4) and [Cu(2,2'-bipy) 2Cl](3-Hsb)·3H 2O ( 5) [3-sb = 3-sulfobenzoate dianion; 2,2'-bipy = 2,2'-bipyridine], have been synthesized by hydrothermal reactions or the combination of hydrothermal reactions and solution evaporation. The molecular structure of complex 1 is a monomer in which the 3-sb monodentately coordinates to the Cu II ion. Complexes 2- 4 exhibit one-dimensional infinite chain structures in which the 3-sb ligands serve as bridges. Complex 5 is a cation-anion species in which the 3-Hsb is non-coordinating. Five complexes exhibit four coordination geometries, irregular geometry between square pyramid and trigonal bipyramid in 1, distorted octahedron in 2, square pyramid in 3- 4, and trigonal bipyramid in 5. These complexes contain lattice and/or coordinated water molecules, therefore extensive hydrogen bonds occur. The extended hydrogen-bonding architectures are 1-D chains for 4 and 5, 2-D layers for 1 and 3, and 3-D network for 2. Complexes 3 and 4 have same crystal system and space group, and afford similar 1-D frameworks but have different lattice water molecules, therefore the addition lattice water molecule in complex 3 leads to more compact packing, longer metal-lattice water distance, and shorter Cu⋯Cu separation by 3-sb compared to those in complex 4. The fluorescent emissions of complexes 1- 3 are stronger than those of ligands, indicating the coordination of 3-sb and 2,2'-bipyridine can enhance the emissions.

  13. Are gas-phase reactions of five-coordinate divalent metal ion complexes affected by coordination geometry?

    Science.gov (United States)

    Combariza, Marianny Y; Fermann, Justin T; Vachet, Richard W

    2004-04-19

    Five-coordinate metal complex ions of the type [ML](2+) [where M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and L= 1,9-bis(2-pyridyl)-2,5,8-triazanonane (DIEN-(pyr)(2)) and 1,9-bis(2-imidazolyl)-2,5,8-triazanonane (DIEN-(imi)(2)] have been reacted with acetonitrile in the gas phase using a modified quadrupole ion trap mass spectrometer. The kinetics and thermodynamics of these reactions show that the reactivity of these complexes is affected by metal electronic structure and falls into three groups: Mn(II) and Ni(II) complexes are the most reactive, Fe(II) and Co(II) complexes exhibit intermediate reactivity, and Cu(II) and Zn(II) complexes are the least reactive. To help explain the experimental trends in reactivity, theoretical calculations have been used. Due to the relatively large size of the metal complexes involved, we have utilized a two-layered ONIOM method to perform geometry optimizations and single point energy calculations for the [ML](2+) and [ML + CH(3)CN](2+) systems. The calculations show that the reactant five-coordinate complexes ([ML](2+)) exhibit structures that are slightly distorted trigonal bipyramidal geometries, while the six-coordinate complexes ([ML + CH(3)CN](2+)) have geometries that are close to octahedral. The Delta G values obtained from the ONIOM calculations roughly agree with the experimental data, but the calculations fail to completely explain the trends for the different metal complexes. The failure to consider all possible isomers as well as adequately represent pi-d interactions for the metal complexes is the likely cause of this discrepancy. Using the angular overlap model (AOM) to obtain molecular orbital stabilization energies (MOSE) also fails to reproduce the experimental trends when only sigma interactions are considered but succeeds in explaining the trends when pi interactions are taken into account. These results indicate that the pi-donor character of the CH(3)CN plays a subtle, yet important, role in

  14. Oxygen-storage behavior and local structure in Ti-substituted YMnO3

    Science.gov (United States)

    Levin, I.; Krayzman, V.; Vanderah, T. A.; Tomczyk, M.; Wu, H.; Tucker, M. G.; Playford, H. Y.; Woicik, J. C.; Dennis, C. L.; Vilarinho, P. M.

    2017-02-01

    Hexagonal manganates RMnO3 (R=Y, Ho, Dy) have been recently shown to exhibit oxygen-storage capacities promising for three-way catalysts, air-separation, and related technologies. Here, we demonstrate that Ti substitution for Mn can be used to chemically tune the oxygen-breathing properties of these materials towards practical applications. Specifically, Y(Mn1-xTix)O3 solid solutions exhibit facile oxygen absorption/desorption via reversible Ti3+↔Ti4+ and Mn3+↔Mn4+ reactions already in ambient air at ≈400 °C and ≈250 °C, respectively. On cooling, the oxidation of both cations is accompanied by oxygen uptake yielding a formula YMn3+1-x-yMn4+yTi4+xO3+δ. The presence of Ti promotes the oxidation of Mn3+ to Mn4+, which is almost negligible for YMnO3 in air, thereby increasing the uptake of oxygen beyond that required for a given Ti4+ concentration. The reversibility of the redox reactions is limited by sluggish kinetics; however, the oxidation process continues, if slowly, even at room temperature. The extra oxygen atoms are accommodated by the large interstices within a triangular lattice formed by the [MnO5] trigonal bipyramids. According to bond distances from Rietveld refinements using the neutron diffraction data, the YMnO3 structure features under-bonded Mn and even more severely under-bonded oxygen atoms that form the trigonal bases of the [MnO5] bipyramids. The tensile bond strain around the 5-fold coordinated Mn site and the strong preference of Ti4+(and Mn4+) for higher coordination numbers likely provide driving forces for the oxidation reaction. Reverse Monte Carlo refinements of the local atomic displacements using neutron total scattering revealed how the excess oxygen atoms are accommodated in the structure by correlated local displacements of the host atoms. Large displacements of the under-bonded host oxygen atoms play a key part in this lattice-relaxation process, facilitating reversible exchange of significant amounts of oxygen with

  15. Redox routes to substitution of aluminum(III): synthesis and characterization of (IP-)2AlX (IP = α-iminopyridine, X = Cl, Me, SMe, S2CNMe2, C≡CPh, N3, SPh, NHPh).

    Science.gov (United States)

    Myers, Thomas W; Holmes, Alexandra L; Berben, Louise A

    2012-08-20

    Redox active ligands are shown to facilitate a variety of group transfer reactions at redox inert aluminum(III). Disulfides can be used as a two-electron group transfer reagent, and we show that (IP(-))(2)AlSR can be formed by reaction of [(THF)(6)Na][(IP(2-))(2)Al] (1c) with disulfides RSSR (where X = C(S)NMe(2), 4; SMe, 5). In a more general redox route to substitution of aluminum bis(iminopyridine) complexes, we report zinc(II) salts as a group transfer reagent. Reaction of [((R)IP(2-))(2)Al](-) (R = H, 1c; Me, 1d) with ZnX(2) affords ((R)IP(-))(2)AlX (where IP = iminopyridine, R = H, and X = Cl, 2; CCPh, 6; N(3), 7; SPh, 8; or R = Me and X = NHPh, 9). Single crystal X-ray diffraction analysis of the complexes reveal that each of the five coordinate complexes reported here has a trigonal bipyramidal geometry with τ = 0.668 - 0.858. We observed a correlation between the greatest deviations from ideal trigonal bipyramidal symmetry (lowest τ values), the bond lengths consistent with smallest degree of ligand reduction, and the least polarizable X ligand in (IP(-))(2)AlX. Complex 4 is six-coordinate and is best described as distorted octahedral. Variable temperature magnetic susceptibility measurements indicate that each of the complexes 3-9 has a biradical electronic structure similar to previously reported 2. Magnetic exchange coupling constants in the range J = -94 to -212 cm(-1) were fit to the data for 2-9 to describe the energy of antiferromagnetic interaction between ligand radicals assuming a spin Hamiltonian of the form Ĥ = -2JŜ(L(1))·Ŝ(L(2)). The strongest coupling occurs when the angle between the ligand planes is smallest, presumably to afford good overlap with the Al-X σ* orbital. Electrochemical properties of the complexes were probed using cyclic voltammetry and each of 3-9 displayed a reversible two-electron reduction and two quasi-reversible one-electron oxidation processes. The energy of the ligand based redox processes for 2-9 differ by

  16. Structural variation in ethylenediamine and -diphosphine adducts of (2,6-Me2C6H3S)2Pb: a single crystal X-ray diffraction and 207Pb solid-state NMR spectroscopy study.

    Science.gov (United States)

    Rossini, Aaron J; Macgregor, Alan W; Smith, Anita S; Schatte, Gabriele; Schurko, Robert W; Briand, Glen G

    2013-07-14

    Coordination complexes of (2,6-Me2C6H3S)2Pb (1) with flexible bidentate ligands have been prepared to explore new bonding environments for Pb(II) thiolates. The reaction of 1 with a series of ethylenediamine and ethylenediphosphine ligands resulted in isolation of the adducts [(2,6-Me2C6H3S)2Pb]2(tmeda) (9), [(2,6-Me2C6H3S)2Pb]3(dmpe) (10) and [(2,6-Me2C6H3S)2Pb]2(dppe) (11) [tmeda = N,N,N',N'-tetramethylethylenediamine; dmpe = bis(dimethylphosphino)ethane; dppe = bis(diphenylphosphino)ethane]. The X-ray crystal structure of 9 shows a dinuclear species in which tmeda is chelating a ψ-trigonal bipyramidal S2N2 Pb centre via axial and equatorial sites. The structure of 10 displays a trinuclear structural unit in which dmpe is chelating a ψ-trigonal bipyramidal S2P2 Pb centre via equatorial sites. Compounds 9 and 10 also contain a second unique metal centre with ψ-tetrahedral S3Pb bonding motifs. The structure of 11 shows the dppe ligand bridging two Pb ψ-tetrahedral S2P metal bonding environments. Static (207)Pb solid-state NMR (SSNMR) spectra of 9-11 and [Ph4As][(PhS)3Pb] (12) were acquired with cross polarization (CP)-CPMG and frequency swept pulse (WURST)-CPMG pulse sequences, and the efficiencies of these pulse sequences are compared. The (207)Pb SSNMR spectra reveal that the lead chemical shift anisotropies (CSA) vary greatly between the different Pb sites, and are generally large in magnitude. DFT calculations are utilized to relate the orientations of the (207)Pb nuclear magnetic shielding tensors to the molecular structures, and to aid in spectral assignment where multiple Pb centres are present. The combination of X-ray diffraction, (207)Pb SSNMR and DFT is shown to be invaluable for the structural characterization of these important structural motifs, and should find wide-ranging application to numerous lead coordination compounds.

  17. Topological hydrogen-bond definition to characterize the structure and dynamics of liquid water.

    Science.gov (United States)

    Henchman, Richard H; Irudayam, Sheeba Jem

    2010-12-23

    A definition that equates a hydrogen bond topologically with a local energy well in the potential energy surface is used to study the structure and dynamics of liquid water. We demonstrate the robustness of this hydrogen-bond definition versus the many other definitions which use fixed, arbitrary parameters, do not account for variable molecular environments, and cannot effectively resolve transition states. Our topology definition unambiguously shows that most water molecules are double acceptors but sizable proportions are single or triple acceptors. Almost all hydrogens are found to take part in hydrogen bonds. Broken hydrogen bonds only form when two molecules try to form two hydrogen bonds between them. The double acceptors have tetrahedral geometry, lower potential energy, entropy, and density, and slower dynamics. The single and triple acceptors have trigonal and trigonal bipyramidal geometry and when considered together have higher density, potential energy, and entropy, faster dynamics, and a tendency to cluster. These calculations use an extended theory for the entropy of liquid water that takes into account the variable number of hydrogen bonds. Hydrogen-bond switching is shown to depend explicitly on the variable number of hydrogen bonds accepted and the presence of interstitial water molecules. Transition state theory indicates that the switching of hydrogen bonds is a mildly activated process, requiring only a moderate distortion of hydrogen bonds. Three main types of switching events are observed depending on whether the donor and acceptor are already sharing a hydrogen bond. The switch may proceed with no intermediate or via a bifurcated-oxygen or cyclic dimer, both of which have a broken hydrogen bond and symmetric and asymmetric forms. Switching is found to be strongly coupled to whole-molecule vibration, particularly for the more mobile single and triple acceptors. Our analysis suggests that even though water is heterogeneous in terms of the

  18. Structural and optical properties of tellurite thin film glasses deposited by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Martin, D.; Fernandez-Navarro, J.M. [Laser Processing Group, Instituto de Optica (CSIC), Serrano 121, 28006 Madrid (Spain); Gonzalo, J., E-mail: j.gonzalo@io.cfmac.csic.es [Laser Processing Group, Instituto de Optica (CSIC), Serrano 121, 28006 Madrid (Spain); Jose, G.; Jha, A. [Institute for Materials Research, University of Leeds, Clarendon Road, Leeds LS2 9JT (United Kingdom); Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica (CSIC), Marie Curie s/n, 28049 Cantoblanco (Spain); Domingo, C. [Instituto de Estructura de la Materia (CSIC), Serrano 121, 28006 Madrid (Spain); Garcia-Lopez, J. [Centro Nacional de Aceleradores, P. Tecnologico ' Cartuja 93' , 41092 Sevilla (Spain)

    2011-10-31

    Tellurite (TeO{sub 2}-TiO{sub 2}-Nb{sub 2}O{sub 5}) thin film glasses have been produced by pulsed laser deposition at room temperature at laser energy densities in the range of 0.8-1.5 J/cm{sup 2} and oxygen pressures in the range of 3-11 Pa. The oxygen concentration in the films increases with laser energy density to reach values very close to that of the bulk glass at 1.5 J/cm{sup 2}, while films prepared at 1.5 J/cm{sup 2} and pressures above 5 Pa show oxygen concentration in excess of 10% comparing to the glass. X-ray photoelectron spectroscopy shows the presence of elementary Te in films deposited at O{sub 2} pressures {<=} 5 Pa that is not detected at higher pressures, while analysis of Raman spectra of the samples suggests a progressive substitution of TeO{sub 3} trigonal pyramids by TeO{sub 4} trigonal bipyramids in the films when increasing their oxygen content. Spectroscopic ellipsometry analysis combined with Cauchy and effective medium modeling demonstrates the influence of these compositional and structural modifications on the optical response of the films. Since the oxygen content determines their optical response through the structural modifications induced in the films, those can be effectively controlled by tuning the deposition conditions, and films having large n (2.08) and reduced k (< 10{sup -4}) at 1.5 {mu}m have been produced using the optimum deposition conditions.

  19. Immobilization of Technetium Waste from Pyro-processing Using Tellurite Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Jong; Pyo, Jae-Young; Lee, Cheong-Won [POSTECH, Pohang (Korea, Republic of); Yang, Jae-Hwan; Park, Hwan-Seo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Vitrification of Tc wastes has been challenging because of the low solubility in the silicate glass and high volatility in the melting process. In previous studies, the measured solubility of Tc and Re was ⁓ 3000 ppm at 1000 .deg. C in low activity waste (LAW) glass. And retention of Tc has been reported within 12 - 77% during the borosilicate vitrification process. Tellurite glasses have been studied for halide waste immobilization due to low melting temperatures (Tm= 600-800 .deg. C) and flexibility of network with foreign ions. Tellurite glasses offered higher halide retention than borosilicate glasses. The structure of pure tellurite (TeO{sub 2}) consists of TeO{sub 4} trigonal bipyramids (tbp), but TeO{sub 4} units are converted to TeO{sub 3} trigonal pyramids (tp) having non-bridging oxygen (NBO) as the modifiers added. Objectives of this study are to investigate the tellurite glasses for Tc immobilization using Re as a surrogate. Retention and waste loading of Re were analyzed during the vitrification process of tellurite glass. We investigated local structures of Re ions in glasses by Raman and X-ray absorption spectroscopies. The tellurite glass was investigated to immobilize the Ca(TcO{sub 4}){sub 2}, surrogated by Ca(ReO{sub 4}){sub 2}. The average of Re retention in tellurite glass was 86%. The 7-day PCT results were satisfied with U.S requirement up to 9 mass% of Ca(ReO{sub 4}){sub 2} content. Re in the tellurite glass exists +7 oxidation state and was coordinated with 4 oxygen.

  20. Crystal structure of hexakis(dmpu-di-μ2-hydroxido-dialuminium tetraiodide dmpu tetrasolvate [dmpu is 1,3-dimethyltetrahydropyrimidin-2(1H-one]: a centrosymmetric dinuclear aluminium complex containing AlO5 polyhedra

    Directory of Open Access Journals (Sweden)

    Daniel Lundberg

    2015-08-01

    Full Text Available The structure of the title compound, [Al2(OH2(C6H12N2O6]I4·4C6H12N2O (systematic name: di-μ2-hydroxido-bis{tris[1,3-dimethyltetrahydropyrimidin-2(1H-one-κO]aluminium} tetraiodide 1,3-dimethyltetrahydropyrimidin-2(1H-one tetrasolvate, is composed of two Al(C6H12N2O3 moieties linked into a centrosymmetric dinuclear unit by a pair of bridging hydroxide ions. The aluminium cations show a distorted trigonal bipyramidal AlO5 coordination environment formed only by monodentate ligands. The Al—O bond lengths are in the range 1.789 (2–1.859 (2 Å (mean bond length = 1.818 Å. The non-coordinating iodide anions compensate the charge of the complex cation. The remaining solvent molecules and the iodide counter-anions interact with the complex cation by weak non-classical C—H...I and C—H...O hydrogen bonds.

  1. Magnetic properties and electronic structure of manganese-based blue pigments: a high-frequency and -field EPR study.

    Science.gov (United States)

    Krzystek, J; Telser, Joshua; Li, Jun; Subramanian, M A

    2015-09-21

    A variety of new oxide-based materials based on hexagonal phase of YInO3 have been recently described. In some of these materials, the In(III) ions are substituted by Mn(III), which finds itself in a trigonal-bipyramidal (TBP) coordination environment. While YInO3 is colorless and YMnO3 is black, mixed systems YIn1-xMnxO3 (0.02 EPR) in its high-frequency and -field version (HFEPR), a technique ideally suited for transition metal ions such as Mn(III) that, in contrast to, for example, Mn(II), are difficult to study by EPR at (conventional) low frequency and field. YIn1-xMnxO3 with 0.02 < x < 0.2 exhibited high-quality HFEPR spectra up to room temperature that could be interpreted as arising from isolated S = 2 paramagnets. A simple ligand-field model, based on the structure and optical spectra, explains the spin Hamiltonian parameters provided by HFEPR, which were D = +3.0 cm(-1), E = 0; g⊥ = 1.99, g∥ = 2.0. This study demonstrates the general applicability of a combined spectroscopic and classical theoretical approach to understanding the electronic structure of novel materials containing paramagnetic dopants. Moreover, HFEPR complements optical and other experimental methods as being a sensitive probe of dopant level.

  2. Structural characterization and electronic properties determination by high-field and high-frequency EPR of a series of five-coordinated Mn(II) complexes.

    Science.gov (United States)

    Mantel, Claire; Baffert, Carole; Romero, Isabel; Deronzier, Alain; Pécaut, Jacques; Collomb, Marie-Noëlle; Duboc, Carole

    2004-10-04

    The isolation, structural characterization, and electronic properties of a series of high-spin mononuclear five-coordinated Mn(II) complexes, [Mn(terpy)(X)(2)] (terpy = 2, 2':6',2' '-terpyridine; X = I(-) (1), Br(-) (2), Cl(-) (3), or SCN(-) (4)), are reported. The X-ray structures of the complexes reveal that the manganese ion lies in the center of a distorted trigonal bipyramid for complexes 1, 2, and 4, while complex 3 is better described as a distorted square pyramid. The electronic properties of 1-4 were investigated by high-field and high-frequency EPR spectroscopy (HF-EPR) performed between 5 and 30 K. The powder HF-EPR spectra have been recorded in high-field-limit conditions (95-285 GHz) (D EPR experiments, the sign of D was unambiguously determined. D is positive for the iodo and bromo complexes and negative for the chloro and thiocyano ones. A structural correlation is proposed. Each complex is characterized by a significant rhombicity with E/D values between 0.17 and 0.29, reflecting the distorted geometry observed around the manganese. Finally, we compared the spin Hamiltonian parameters of our five-coordinated complexes and those previously reported for other analogous series of dihalo four- and six-coordinated complexes. The effect of the coordination number and of the geometry of the Mn(II) complexes on the spin Hamiltonian parameters is discussed.

  3. A five-coordinate manganese(iii) complex of a salen type ligand with a positive axial anisotropy parameter D.

    Science.gov (United States)

    Shova, Sergiu; Vlad, Angelica; Cazacu, Maria; Krzystek, J; Bucinsky, Lukas; Breza, Martin; Darvasiová, Denisa; Rapta, Peter; Cano, Joan; Telser, Joshua; Arion, Vladimir B

    2017-09-12

    A new high-spin d4 roughly trigonal-bipyramidal (TBP) manganese(iii) complex with a salen type ligand (H2L), namely MnL(NCS)·0.4H2O, has been synthesised and characterised by elemental analysis, ESI mass spectrometry, IR and UV-vis spectroscopy, and spectroelectrochemistry. X-ray diffraction analysis revealed an axial compression of the approximate TBP. Temperature dependent magnetic susceptibility and variable-temperature variable-field (VTVH) magnetisation measurements, as well as high-frequency and -field EPR (HFEPR) spectroscopy, were used to accurately describe the magnetic properties of this complex and, in particular, determine the spin Hamiltonian parameters: g-values and the zero-field splitting (ZFS) parameters D and E. The HFEPR spectra allowed the extraction of fourth order ZFS parameters. Quantum chemical calculations reproduced well the electronic and geometric structures of this unusual complex and, in particular, its electronic absorption spectrum along with the spin Hamiltonian parameters.

  4. A one-dimensional chain structure based on unusual tetranuclear manganese(II) clusters.

    Science.gov (United States)

    Che, Guang Bo; Wang, Jian; Liu, Chun Bo; Li, Xiu Ying; Liu, Bo

    2008-11-01

    The title coordination polymer, poly[bis(mu(4)-biphenyl-2,2'-dicarboxylato)(dipyrido[3,2-a:2',3'-c]phenazine)manganese(II)], [Mn(2)(C(14)H(8)O(4))(2)(C(18)H(10)N(4))](n), was obtained through the reaction of MnCl(2).4H(2)O, biphenyl-2,2'-dicarboxylic acid (H(2)dpdc) and dipyrido[3,2-a:2',3'-c]phenazine (L) under hydrothermal conditions. The asymmetric unit contains two crystallographically unique Mn(II) ions, one unique L ligand and two unique dpdc ligands. One Mn ion is six-coordinated by four O atoms from three different dpdc ligands and two N atoms from one L ligand, adopting a distorted octahedral coordination geometry. The distortions from ideal octahedral geometry are largely due to the presence of chelating ligands and the resulting acute N-Mn-N and O-Mn-O angles. The second Mn ion is coordinated in a distorted trigonal bipyramidal fashion by five O atoms from four distinct dpdc ligands. Four Mn(II) ions are bridged by the carboxylate groups of the dpdc ligands to form an unusual tetranuclear Mn(II) cluster. Clusters are further connected by the aromatic backbone of the dicarboxylate ligands, forming a one-dimensional chain structure along the b axis. The title compound is the first example of a chain structure based on a tetranuclear Mn(II) cluster.

  5. Effect of self-assembly of fullerene nano-particles on lipid membrane.

    Science.gov (United States)

    Zhang, Saiqun; Mu, Yuguang; Zhang, John Z H; Xu, Weixin

    2013-01-01

    Carbon nanoparticles can penetrate the cell membrane and cause cytotoxicity. The diffusion feature and translocation free energy of fullerene through lipid membranes is well reported. However, the knowledge on self-assembly of fullerenes and resulting effects on lipid membrane is poorly addressed. In this work, the self-assembly of fullerene nanoparticles and the resulting influence on the dioleoylphosphtidylcholine (DOPC) model membrane were studied by using all-atom molecular dynamics simulations with explicit solvents. Our simulation results confirm that gathered small fullerene cluster can invade lipid membrane. Simulations show two pathways: 1) assembly process is completely finished before penetration; 2) assembly process coincides with penetration. Simulation results also demonstrate that in the membrane interior, fullerene clusters tend to stay at the position which is 1.0 nm away from the membrane center. In addition, the diverse microscopic stacking mode (i.e., equilateral triangle, tetrahedral pentahedral, trigonal bipyramid and octahedron) of these small fullerene clusters are well characterized. Thus our simulations provide a detailed high-resolution characterization of the microscopic structures of the small fullerene clusters. Further, we found the gathered small fullerene clusters have significant adverse disturbances to the local structure of the membrane, but no great influence on the global integrity of the lipid membrane, which suggests the prerequisite of high-content fullerene for cytotoxicity.

  6. Deuterium ordering in Laves phase deuteride YFe2D4.2

    Energy Technology Data Exchange (ETDEWEB)

    Proffen, Thomas Ernst [Los Alamos National Laboratory; Ropka, Joanna [UNIV OF GENEVA; Cerny, Radovan [UNIV OF GENEVA; Paul - Boncour, V [CNRS

    2009-01-01

    The structure of Laves phase deuteride YFe{sub 2}D{sub 4.2} has been investigated by synchrotron and neutron (ToF) powder diffraction experiments between 60 K and 370 K. YFe{sub 2}D{sub 4.2} crystallizes below 323K in fully ordered monoclinic structure (s.g. Pc, Z = 8, a = 5.50663(4), b = 11.4823(1), c = 9.42919(6) {angstrom}, {beta} = 122.3314(5){sup o}, V = 503.765(3) {angstrom}{sup 3} at 290K) containing 4 yttrium, 8 iron and 18 deuterium atoms. Most of D-D distances are within the precision of the diffraction experiment longer than 2.1 {angstrom}, the shortest ones are of 1.96 {angstrom}. Seven iron atoms from eight are coordinated by deuterium in a trigonal bipyramid, similar to that in TiFeD{sub 1.95-2}. The eights iron atom is coordinated by deuterium in a tetrahedral configuration. The iron coordination by deuterium, and iron-deuterium distances points to the importance of the directional bonding between iron and deuterium atoms. The lowering of crystal symmetry due to deuterium ordering occurs at much higher temperature than magnetic order, and is therefore one of the parameters which are at the origin of magnetic transition at lower temperatures.

  7. Tetra-μ3-iodido-tetrakis[(tri-n-butylphosphane-κPcopper(I

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    Simon Klenk

    2014-04-01

    Full Text Available The title complex, [Cu4I4(C12H27P4], crystallizes with six molecules in the unit cell and with three independent one-third molecule fragments, completed by application of the relevant symmetry operators, in the asymmetric unit. The tetranuclear copper core shows a tetrahedral geometry (site symmetry 3... The I atoms also form a tetrahedron, with I...I distances of 4.471 (1 Å. Both tetrahedra show an orientation similar to that of a pair of self-dual platonic bodies. The edges of the I-tetrahedral structure are capped to the face centers of the Cu-tetrahedron and vice versa. The Cuface...I distances are 2.18 Å (averaged and the Iface...Cu distances are 0.78 Å (averaged. As a geometric consequence of these properties there are eight distorted trigonal–bipyramidal polyhedra evident, wherein each trigonal face builds up the equatorial site and the opposite Cu...I positions form the axial site. As expected, the n-butyl moieties are highly flexible, resulting in large elongations of their anisotropic displacement parameters. Some C atoms of the n-butyl groups were needed to fix alternative discrete disordered positions.

  8. Frustrated Antiferroelectricity in a Room-Temperature Ferrimagnet: Promising Candidate Toward Multiple State Memory

    Science.gov (United States)

    Wang, Panshuo; Xiang, Hongjun

    2014-03-01

    Frustration refers to the presence of competing forces that cannot be simultaneously satisfied. However, geometrical frustration in ferroelectrics is highly unusual. Here we show from first-principles calculations that the M-type hexaferrite BaFe12O19 exhibits frustrated antiferroelectricity, and hence resolve the experimental controversy on the local structure of the trigonal bipyramidal (TBP) site. Due to the electrostatic interaction, the high-spin Fe3+ ions at the TBP sites are displaced from the mirror-plane sites to generate local dipole moments along the c axis. Because of the dipole-dipole interactions, the ground state of BaFe12O19 is a(2 × 1) chain-like antiferroelectric (AFE) phase. Our work indicates that the ferroelectric state is metastable and can be reached by applying an external electric field to the AFE state, and that the FE state can be made stable at room temperature by element substitution or strain engineering. Thus M-type hexaferrites not only provide platform for studying the new physics of the frustrated antiferroelectricity, but also are promising candidates for realizing multiple state memory devices based on the coexistence of the room temperature polar order and strong ferrimagnetic order.

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

    Science.gov (United States)

    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.

  10. Synthesis and spectral, antibacterial, molecular studies of biologically active organosilicon(IV complexes

    Directory of Open Access Journals (Sweden)

    Har Lal Singh

    2017-06-01

    Full Text Available A series of new organosilicon(IV complexes have general formulae R3SiL and RSiLOEt with Schiff bases (R = Me and Ph. The Schiff bases (LH have been derived from the condensation of (2-hydroxyphenyl(pyrrolidin-1-ylmethanone with semicarbazide, thiosemicarbazide, and phenylthiosemicarbazide, respectively. The compounds have been characterized by the elemental analysis, molar conductance, and spectral (UV, IR, 1H, 13C, and 29Si NMR studies. These studies showed that the ligands coordinate with the silicon atom in a tridentate manner through phenolic oxygen, azomethine nitrogen and thiolic sulfur. Further applying experimental spectroscopic techniques, theoretical data calculated using density functional theory by B3LYP/6.31+g(d,p has also been used for structural determination. The resulting complexes have been proposed to have trigonal bipyramidal and distorted octahedral geometries. Few representative Schiff base and their silicon complexes have been screened for their in vitro antibacterial activity against Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC of selected compounds was determined. The screening results show that organosilicon(IV complexes have better antibacterial activity than the free ligands.

  11. Intermediate (S = 1) spin state in five-coordinate cobalt(III): magnetic properties of N-o-hydroxy-benzamido-meso-tetraphenylporphyrin cobalt(III), Co(N-NCO(o-O)C6H4-tpp).

    Science.gov (United States)

    Cho, Cheng-Hsiung; Chien, Ting-Yuan; Chen, Jyh-Horung; Wang, Shin-Shin; Tung, Jo-Yu

    2010-03-14

    The crystal structures of paramagnetic N-o-oxido-benzimido-meso-tetraphenylporphyrinato (-kappa(4),N(1),N(2),N(3),N(5),kappaO(2))cobalt(III) [Co(N-NCO(o-O)C(6)H(4)-tpp); 2] (S = 1) and diamagnetic N-o-oxido-benzimido-meso-tetraphenylporphyrinato (-kappa(4),N(1),N(2),N(3),N(5),kappaO(2)) gallium(III) chloroform.methanol solvate [Ga(N-NCO(o-O)C(6)H(4)-tpp).0.5CHCl(3).MeOH; 3.0.5CHCl(3).MeOH] (S = 0) were determined. The coordination sphere around Co(III) in 2 [or Ga(III) in 3.0.5CHCl(3).MeOH] is described as five-coordinate distorted trigonal bipyramid (DTBP) with O(1), N(1) and N(3) [or O(2), N(1), N(3)] lying in the equatorial plane for 2 [or 3.0.5CHCl(3).MeOH]. The magnitude of axial (D) zero-field splitting (ZFS) for the Co(III) (S = 1) in 2 was determined as approximately 107 cm(-1) by paramagnetic susceptibility measurements. The compound (2) reacts in donor solvent such as pyridine to form six-coordinate diamagnetic species of the type Co(N-NCO(o-O)C(6)H(4)-tpp)(py) (4), whose (1)H NMR spectra can be interpreted as for Co(III) in an octahedral environment.

  12. Chloridobis(2,9-diethoxy-1,10-phenanthroline-κ2N,N′copper(II perchlorate

    Directory of Open Access Journals (Sweden)

    Lei Meng

    2009-01-01

    Full Text Available In the title complex, [CuCl(C16H16N2O22]ClO4, the CuII ion is coordinated by four N atoms from two chelating 2,9-diethoxy-1,10-phenanthroline ligands and one chloride ion in a slightly disorted trigonal-bipyramidal environment. Two N atoms and the Cl atom are in equatorial positions while the remaining two N atoms occupy apical sites, the equatorial Cu—N bonds being significantly longer than the two apical Cu—N bonds. The N=C—O—C torsion angles involving the four ethoxy groups are in the range 161.5 (8 to 177.0 (5°. In the crystal structure, there are significant π–π stacking interactions between inversion-related rings of phenanthroline groups with centroid–centroid distances in the range 3.649 (4–3.790 (4 Å.

  13. Synthesis and structure of a new family of 3d-4f heterometallic compounds Rb7LnFe6O2(PO4)8 (Ln=Sm, Eu, Gd, Dy): Magnetic properties of the Sm-, Gd-, Dy-derivatives

    Science.gov (United States)

    Sanjeewa, Liurukara D.; Palmer West, J.; Hwu, Shiou-Jyh

    2012-08-01

    A new family of mixed lanthanide(III) and iron(III) oxo-phosphate phases, Rb7LnFe6O2(PO4)8 (Ln=Sm 1, Eu 2, Gd 3, Dy 4), was isolated by using a high-temperature, solid-state method in molten-salt media. The X-ray single-crystal structure analysis shows that these isomorphic derivatives crystallize in a triclinic space group P-1 (no. 2); Z=1. The 3-D framework of these 3d-4f oxo-phosphates are comprised of LnO6 octahedral, FeO5 trigonal bipyramidal (tbp), and μ3-oxo [Fe4O18] tetrameric units interconnected through PO4 tetrahedra. The preliminary results of the temperature-dependent magnetic susceptibility measurements for selected compounds (1, 3, 4) reveal antiferromagnetic-like behavior. 1 shows a weak antiferromagnetric ordering at TN=˜7 K while others show little evidence of long-range magnetic order down to 2 K. All three compounds have measured magnetic moments significantly smaller than the expected values.

  14. Effect of self-assembly of fullerene nano-particles on lipid membrane.

    Directory of Open Access Journals (Sweden)

    Saiqun Zhang

    Full Text Available Carbon nanoparticles can penetrate the cell membrane and cause cytotoxicity. The diffusion feature and translocation free energy of fullerene through lipid membranes is well reported. However, the knowledge on self-assembly of fullerenes and resulting effects on lipid membrane is poorly addressed. In this work, the self-assembly of fullerene nanoparticles and the resulting influence on the dioleoylphosphtidylcholine (DOPC model membrane were studied by using all-atom molecular dynamics simulations with explicit solvents. Our simulation results confirm that gathered small fullerene cluster can invade lipid membrane. Simulations show two pathways: 1 assembly process is completely finished before penetration; 2 assembly process coincides with penetration. Simulation results also demonstrate that in the membrane interior, fullerene clusters tend to stay at the position which is 1.0 nm away from the membrane center. In addition, the diverse microscopic stacking mode (i.e., equilateral triangle, tetrahedral pentahedral, trigonal bipyramid and octahedron of these small fullerene clusters are well characterized. Thus our simulations provide a detailed high-resolution characterization of the microscopic structures of the small fullerene clusters. Further, we found the gathered small fullerene clusters have significant adverse disturbances to the local structure of the membrane, but no great influence on the global integrity of the lipid membrane, which suggests the prerequisite of high-content fullerene for cytotoxicity.

  15. Bis(1,10-phenanthroline-κ2N,N′(sulfato-κOcopper(II ethanol monosolvate

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    Natthaya Meundaeng

    2013-10-01

    Full Text Available The crystal structure of the title compound, [Cu(SO4(C12H8N22]·C2H5OH, arises from the assembly of the neutral complex [Cu(SO4(C12H8N22] and an ethanol solvent molecule. The CuII ion is five-coordinate, surrounded by two pairs of N atoms from two independent N,N′-chelating 1,10-phenanthroline ligands, and one O atom of monodentate sulfate ligand, in a distorted trigonal-bipyramidal fashion. Spatial orientation of the ligands and the assembly in the solid state are stabilized by the C—H...O hydrogen-bonding interactions, established between the O atoms (from the sulfate ligand and the ethanol molecule and the neighbouring 1,10-phenanthroline molecules. There is also an offset face-to-face π–π stacking between the 1,10-phenanthroline ligands. The ethanol solvent molecule is disordered over two orientations in the ratio 0.663 (10:0.337 (10. The crystal examined was subject to racemic twinning and the refined twin fraction was 0.346 (19.

  16. (Benzoato-κObis(1,10-phenanthroline-κ2N,N′copper(II chloride benzoic acid disolvate

    Directory of Open Access Journals (Sweden)

    Wen-Xiang Huang

    2010-05-01

    Full Text Available In the title complex, [Cu(C7H5O2(C12H8N22]Cl·2C6H5COOH, the CuII ion is coordinated by one carboxylate O atom from a benzoate anion and four N atoms from two phenantroline ligands in a distorted five-coordinate trigonal-bipyramidal CuON4 chromophore. The Cu2+ and the Cl− ion are imposed by a twofold rotation axiss which also bisects the equally disordered benzoate anion. In the crystal, the molecules are assembled into chains along [010] by C—H...Cl, O—H...Cl and C—H...O hydrogen-bonding interactions. The resulting chains are further connected into two-dimensional supramolecular layers parallel to [100] by interchain π...π stacking interactions [centroid–centroid distance = 3.823 (5 Å] between the phenanthroline ligands and the benzoic acid molecules, and by C—H...O hydrogen-bonding interactions. Strong π...π stacking interactions between adjacent phenantroline ligands [3.548 (4 Å] assemble the layers into a three-dimensional supramolecular architecture.

  17. Chloridobis(1,10-phenanthroline-κN,N')copper(II) tetra-kis-(nitrato-κO,O')(1,10-phenanthroline-κN,N')terbate(III).

    Science.gov (United States)

    Gao, Guo-Ran; Man, Hong-Xue; Xiao, Zhi-Chang; Deng, Yu-Heng

    2011-06-01

    The title complex salt, [CuCl(C(12)H(8)N(2))(2)][Tb(NO(3))(4)(C(12)H(8)N(2))], consists of discrete [CuCl(phen))(2)](+) cations and [Tb(NO(3))(4)(phen)](-) anions (phen is 1,10-phenanthroline). The [CuCl(phen))(2)](+) cation contains a five-coordinate Cu(2+) ion, ligated by two bidentate phen ligands and one Cl(-) ion, exhibiting a distorted CuN(4)Cl trigonal-bipyramidal geometry. In the [Tb(NO(3))(4)(phen)](-) anion, the Tb(3+) ion is coordinated by one chelating phen ligand and four chelating nitrates, forming a distorted TbN(2)O(8) bicapped dodeca-hedral configuration. The anions and cations are assembled into a three-dimensional network by weak C-H⋯Cl and C-H⋯O hydrogen bonds. There is also a significant π-π stacking inter-action, with a centroid-centroid distance of 3.635 (2) Å.

  18. (Benzoato-κO)bis-(1,10-phenanthroline-κN,N')copper(II) chloride benzoic acid disolvate.

    Science.gov (United States)

    Huang, Wen-Xiang; Liu, Bin-Bin; Lin, Jian-Li

    2010-04-02

    In the title complex, [Cu(C(7)H(5)O(2))(C(12)H(8)N(2))(2)]Cl·2C(6)H(5)CO-OH, the Cu(II) ion is coordinated by one carboxyl-ate O atom from a benzoate anion and four N atoms from two phenantroline ligands in a distorted five-coordinate trigonal-bipyramidal CuON(4) chromophore. The Cu(2+) and the Cl(-) ion are imposed by a twofold rotation axiss which also bisects the equally disordered benzoate anion. In the crystal, the mol-ecules are assembled into chains along [010] by C-H⋯Cl, O-H⋯Cl and C-H⋯O hydrogen-bonding inter-actions. The resulting chains are further connected into two-dimensional supra-molecular layers parallel to [100] by inter-chain π⋯π stacking inter-actions [centroid-centroid distance = 3.823 (5) Å] between the phenanthroline ligands and the benzoic acid mol-ecules, and by C-H⋯O hydrogen-bonding inter-actions. Strong π⋯π stacking inter-actions between adjacent phenantroline ligands [3.548 (4) Å] assemble the layers into a three-dimensional supra-molecular architecture.

  19. Synthetic and structural studies on copper 1 H-[1,10]-phenanthrolin-2-one coordination complexes: isolation of a novel intermediate during 1,10-phenanthroline hydroxylation.

    Science.gov (United States)

    Szpakolski, Katherine B; Latham, Kay; Rix, Colin J; White, Jonathan M; Moubaraki, Boujemaa; Murray, Keith S

    2010-02-01

    The synthesis and crystal structure elucidation of a novel dinuclear heteroleptic copper(II) complex has led to an alternative mechanism in the formation of covalent hydrates. During further studies on the synthesis and properties of [Cu(2)(ophen)(2)] (1), a dinuclear complex of copper(I) with 1 H-[1,10]-phenanthrolin-2-one (Hophen), two intermediates/alternative products 2 and 3 were isolated. The dinuclear, antiferromagnetic complex [Cu(2)(ophen)(2)(phen)(2)](NO(3))(2)9H(2)O (3, phen=1,10-phenanthroline) contains two five-coordinate copper(II) ions, both with trigonal-bipyramidal coordination, which are bridged together through deprotonated hydroxyl groups with a Cu--Cu non-bonding distance of 3.100 A. Complex [Cu(phen)(2)(H(2)O)](NO(3))(2) (2) is a polymorph of a previously reported material. The occurrence of 2 and 3 has led us to propose a variation to the Gillard mechanism for the formation of covalent hydrates in bidentate N-heterocycles in which the attacking nucleophile may be the deprotonated form of 2, [Cu(phen)(2)(OH)](-), rather than free OH(-).

  20. Structure of complexes of nitrilo tris methylene phosphonic acid with copper, [CuN(CH2PO3)3(H2O)3] and Na4[CuN(CH2PO3)3]2 · 19H2O, as bactericides and inhibitors of scaling and corrosion

    Science.gov (United States)

    Somov, N. V.; Chausov, F. F.

    2015-03-01

    Nitrilotris methylene phosphonate triaqua copper and octasodium bis(nitrilotris methylene phosphonate cuprate(II)) nonadecahydrate have been synthesized and investigated. [CuN(CH2PO3)3(H2O)3] is crystallized in the sp. gr. P21/ c, Z = 4, a = 9.2506(2) Å, b = 15.9815(2) Å, c = 9.5474(2) Å, β = 113.697(2)°. The copper atom is coordinated by oxygen atoms in the configuration of elongated octahedron; the ligand (of bridge type) links neighboring copper atoms. Na8[CuN(CH2PO3)3]2 · 19H2O is crystallized in the sp. gr. P21/ c, Z = 2, a = 11.24550(10) Å, b = 17.38980(10) Å, c = 13.5852(2) Å, β = 127.8120(10)°. This complex is chelating; the copper atom closes three five-membered N-C-P-O-Cu cycles with a shared Cu-N bond. Copper is coordinated in a distorted trigonal-bipyramidal configuration.

  1. Bis(1,10-phenanthroline-κ(2) N,N')(sulfato-κO)copper(II) ethanol monosolvate.

    Science.gov (United States)

    Meundaeng, Natthaya; Prior, Timothy J; Rujiwatra, Apinpus

    2013-01-01

    The crystal structure of the title compound, [Cu(SO4)(C12H8N2)2]·C2H5OH, arises from the assembly of the neutral complex [Cu(SO4)(C12H8N2)2] and an ethanol solvent mol-ecule. The Cu(II) ion is five-coordinate, surrounded by two pairs of N atoms from two independent N,N'-chelating 1,10-phenanthroline ligands, and one O atom of monodentate sulfate ligand, in a distorted trigonal-bipyramidal fashion. Spatial orientation of the ligands and the assembly in the solid state are stabilized by the C-H⋯O hydrogen-bonding inter-actions, established between the O atoms (from the sulfate ligand and the ethanol mol-ecule) and the neighbouring 1,10-phenanthroline mol-ecules. There is also an offset face-to-face π-π stacking between the 1,10-phenanthroline ligands. The ethanol solvent mol-ecule is disordered over two orientations in the ratio 0.663 (10):0.337 (10). The crystal examined was subject to racemic twinning and the refined twin fraction was 0.346 (19).

  2. Copper(II) chemistry of the functionalized macrocycle cyclam tetrapropionic acid.

    Science.gov (United States)

    Comba, Peter; Emmerling, Franziska; Jakob, Maik; Kraus, Werner; Kubeil, Manja; Morgen, Michael; Pietzsch, Jens; Stephan, Holger

    2013-05-07

    The Cu(II) complex of H(4)TETP (H(4)TETP = 1,4,8,11-tetraazatetradecane-1,4,8,11-tetrapropionic acid) is five-coordinate with a distorted square-pyramidal structure (τ = 0.45; i.e. the geometry is nearly half-way between square-pyramidal and trigonal-bipyramidal) and a relatively long Cu-N and a short Cu-O bond; the comparison between powder and solution electronic spectroscopy, the frozen solution EPR spectrum and ligand-field-based calculations (angular overlap model, AOM) indicate that the solution and solid state structures are very similar, i.e. the complex has a relatively low "in-plane" and a significant axial ligand field with a d(x(2)-y(2)) ground state. The ligand-enforced structure is therefore shown to lead to a partially quenched Jahn-Teller distortion and to a relatively low complex stability, lower than with the corresponding acetate-derived ligand H(4)TETA. This is confirmed by potentiometric titration and by the biodistribution with (64)Cu-labeled ligands which show that the uptake in the liver is significantly increased with the H(4)TETP-based system.

  3. Synthesis, spectroscopic, anticancer, antibacterial and antifungal studies of Ni(II) and Cu(II) complexes with hydrazine carboxamide, 2-[3-methyl-2-thienyl methylene

    Science.gov (United States)

    Chandra, Sulekh; Vandana; Kumar, Suresh

    2015-01-01

    Schiff's base ligand(L) hydrazine carboxamide, 2-[3-methyl-2-thienyl methylene] and its metal complexes have been synthesized and characterized by elemental analysis, molar conductance, various spectroscopic techniques such as electronic, IR, 1H NMR, mass, EPR. Molar conductance of complexes in DMF solution corresponds to non-electrolyte. Complexes have general composition [M(L)2X2], where M = Ni(II) and Cu(II), X = Cl-, NO3-, CH3COO- and ½SO42-. On the basis of above spectral studies, an octahedral geometry has been assigned for Ni(II) complexes and tetragonal geometry for Cu(II) complexes except [Cu(L)2SO4] which possesses five coordinated trigonal bipyramidal geometry. These metal complexes were also tested for their anticancer, antibacterial and antifungal activities to assess their inhibition potential. Anticancer activity of ligand and its metal complexes were evaluated using SRB fluorometric assay and Adriamycin (ADR) was applied as positive control. Schiff's base ligand and its metal complexes were screened for their antibacterial and antifungal activity against Escherichia coli, Bacillus cereus and Aspergillus niger, Aspergillus flavus, respectively. Kirby-Bauer single disk susceptibility test was used for antibacterial activity and well diffusion method for antifungal activity of the compounds on the used fungi.

  4. Spiro copper(II)-metallacycles derived from 5-arylaminomethylene-barbituric acids: Synthesis and structural characterization

    Science.gov (United States)

    Fırıncı, Erkan; Giziroglu, Emrah; Celepci, Duygu Barut; Söyleyici, Hakan Can; Aygün, Muhittin

    2017-06-01

    Schiff bases derived from 2,4,6-trioxohexahydroprimidine-5-carbaldehyde can behave as chelating ligands. 5-[(2,6-diisopropylphenylamino)-methylene]pyrimidine-2,4,6-trione (LB1) and 1,3-dimethyl-5-[(2-phenoxyphenylamino)-methylene]pyrimidine-2,4,6-trione (LB2) were used as ligand in the synthesis of novel mononuclear five-coordinated copper(II) complexes. The spectroscopic properties of the ligands were detected by FT-IR and NMR. The molecular structure of LB2 was determined by X-ray diffraction which crystallizes in the orthorhombic Pca21 space group. The complexes of Cu(LB1)2 (2) and Cu(LB2)2 (3) were characterized by elemental analysis, FT-IR and X-ray diffraction. The X-ray diffraction studies reveal 2 and 3 contain five-coordinated Cu(II) atom which is surrounded by two nitrogen and three oxygen atoms. The coordination geometry of complexes were examined using the Addison's model. The results show that complex 2 has distorted trigonal bipyramidal geometry, but complex 3 has distorted square pyramidal geometry. Also, the synthesized copper complexes can be regarded as spiro metallacycles in which copper is central spiro atom.

  5. Mononuclear nitrogen/sulfur-ligated zinc methoxide and hydroxide complexes: investigating ligand effects on the hydrolytic stability of zinc alkoxide species.

    Science.gov (United States)

    Garner, Dewain K; Fitch, Sarah B; McAlexander, Lenore H; Bezold, Lisa M; Arif, Atta M; Berreau, Lisa M

    2002-08-28

    The synthesis and properties of mononuclear zinc methoxide ([(ebnpa)Zn-OCH3]ClO4) (1) and hydroxide ([(ebnpa)Zn-OH]ClO4) (2) complexes of a new mixed nitrogen/sulfur ligand (ebnpa = N-2-(ethylthio)ethyl-N,N-bis(6-neopentylamino-2-pyridylmethyl)amine) are reported. The structures of 1 and 2 were determined by X-ray diffraction. Each possesses a single zinc-coordinated anion (methoxide or hydroxide) and exhibits an overall trigonal bipyramidal geometry. Structural and spectroscopic studies indicate the presence of two hydrogen-bonding interactions involving the oxygen atom of the zinc-bound anion in each complex. Treatment of [(ebnpa)Zn-OH]ClO4 with CH3OH results in the formation of an equilibrium mixture of 1 and 2. 1H NMR spectroscopic methods were used to examine the equilibrium as a function of temperature, yielding KMe (304 K) = 0.30(8), DeltaHMe = -0.9(1) kcal/mol, and DeltaSMe = -5(1) eu. The negative enthalpy indicates that spontaneous zinc alkoxide formation from a hydroxide precursor occurs in this system at low temperature. Using the experimentally determined DeltaHMe value, we found the homolytic Zn-O bond dissociation energy (BDE) in the Zn-OCH3 unit to be approximately -14 kcal/mol relative to the Zn-O BDE in the Zn-OH unit.

  6. The reaction between ZnO and Molten K2S2O7 forming K2Zn(SO4)2, studied by Raman and IR Spectroscopy and X-ray Diffraction

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Nielsen, Kurt; Boghosian, Soghomon

    1999-01-01

    The reaction between zinc oxide and molten potassium pyrosulfate at 500 °C was shown by Raman spectroscopy to be a 1:1 reaction. By lovering the temperature, colorless crystals could be formed. The crystal structure was determined: Space group = P21/c, Z = 4, a = 5.3582(11), b = 8.7653(18), c = 16.......153(3) Å, b = 91.78(3)o, wR2 = 0.0758 for all 1930 ? independent reflections. The compound, K2Zn(SO4)2, contained trigonally bipyramidal zinc coordinated to five oxygen atoms, with Zn-O bonds of normal length (~ 2.04 ± 0.05 Å), equitorial bonds being slightly shorter on the average. The O-Zn-O angles were...... approximately 90o and 120o. The oxygens were all bridging to the two sulfur atoms forming nearly perfect tetrahedral SO42- groups. The K+ ions were placed in between these ZnO5 hexahedra, which formed a three-dimensional network. Bond distances and angles are compared with literature values. Empirical...

  7. Organotin(IV Derivatives of 2-Acetylpyridine-N(4-Phenylthiosemicarbazone, HAP4P, and 2-Hydroxyacetophenone-N(4-Phenylthiosemicarbazone, H2DAP4P: Crystal and Molecular Structure of [SnMe2(DAP4P] and [SnBu2(DAP4P

    Directory of Open Access Journals (Sweden)

    Sousa Gerimário F. de

    2001-01-01

    Full Text Available The reactions of 2-acetylpyridine-N(4-phenylthiosemicarbazone, HAP4P, and 2-hydroxyacetophenone-N(4-phenylthiosemicarbazone, H2DAP4P, with R4-mSnXm (m = 2, 3; R = Me, nBu, Ph and X = Cl, Br led to the formation of hexa- and penta-coordinated organotin(IV complexes, which were studied by microanalysis, IR, ¹H-NMR and Mössbauer spectroscopies. The molecular structures of [SnMe2(DAP4P] and [Sn nBu2(DAP4P] were determined by single-crystal X-ray diffraction studies. In the compounds [SnClMe2(AP4P] and [SnBrMe2(AP4P], the deprotonated ligand AP4P- is N,N,S-bonded to the Sn(IV atoms, which exhibit strongly distorted octahedral coordination. The structures of [SnMe2(DAP4P] and [Sn nBu2(DAP4P] revealed that the DAP4P2- anion acts as a O,N,S-tridentate ligand. In these cases, the Sn(IV atoms adopt a strongly distorted trigonal bipyramidal configuration where the azomethine N and the two C atoms are on the equatorial plane while the O and the S atoms occupy the axial positions.

  8. Germanium Compounds Containing Ge═E Double Bonds (E = S, Se, Te) as Single-Source Precursors for Germanium Chalcogenide Materials.

    Science.gov (United States)

    Kim, Hyo-Suk; Jung, Eun Ae; Han, Seong Ho; Han, Jeong Hwan; Park, Bo Keun; Kim, Chang Gyoun; Chung, Taek-Mo

    2017-04-03

    New germanium chalcogenide precursors, S═Ge(dmamp)2 (3), S═Ge(dmampS)2 (4), Se═Ge(dmamp)2 (5), Se═Ge(dmampS)2 (6), Te═Ge(dmamp)2 (7), and Te═Ge(dmampS)2 (8), were synthesized from Ge(dmamp)2 (1) and Ge(dmampS)2 (2) using sulfur, selenium, and tellurium powders (dmamp = 1-dimethylamino-2-methyl-2-propanolate, dmampS = 1-dimethylamino-2-methylpropane-2-thiolate). Complexes 1 and 2 were synthesized from metathesis reactions of GeCl2·dioxane with 2 equiv of aminoalkoxide or aminothiolate ligands. Thermogravimetric analysis of complex 1 displayed good thermal stability and volatility. The molecular structures of complexes 2-8 from X-ray single crystallography showed distorted trigonal bipyramidal geometry at the germanium centers. Germanium chalcogenide materials (GeSe and GeTe) were obtained from the thermal decomposition of complexes 5, 6, and 8 in hexadecane. X-ray diffraction patterns exhibited that GeSe and GeTe had orthorhombic and rhombohedral phases, respectively. This study affords a facile method to easily prepare germanium chalcogenide materials using well-designed and stable complexes by thermal decomposition of single-source precursors in solution.

  9. Di-n-butyl{1-[1-(2-hydroxyphenylethylidene]-5-[1-(2-oxidophenylethylidene]thiocarbazonato-κ3O5,N5,S}tin(IV

    Directory of Open Access Journals (Sweden)

    Md. Abu Affan

    2010-06-01

    Full Text Available The `symmetrical' 1,5-bis[1-(2-hydroxyphenylethylidene]thiocarbazone Schiff base condenses with dibutyltin oxide to form the title complex, [Sn(C4H92(C17H16N4O2S], in which the deprotonated ligand O,N,S-chelates to the Sn atom of two crystallographically independent molecules. The ligand bears a formal negative charge on the S and one O atom; the other O atom retains its H atom. The Sn atoms are five-coordinated in a cis-C2NOSSn trigonal-bipyramidal environment, and the apical sites are occupied by the O and S atoms. In both molecules, the hydroxy group is hydrogen bonded to a double-bonded N atom, generating a six-membered ring. The amino group is a donor to the coordinated O atom of an adjacent molecule, the hydrogen-bonding interaction giving rise to a helical chain running along the b axis. In one of the independent molecules, the atoms of one of the n-butyl groups are disordered over two sets of sites with equal occupancy. In the other independent molecule, the atoms of both n-butyl groups are disordered over two sets of sites with equal occupancy and, in addition, the Sn and S atoms were also refined as disordered over two sets of sites with equal occupancy.

  10. Synthesis and spectroscopic characterization of dicyanamido-Cu(II) complexes. Part 2 : Crystal structure of the complexes of tris[2-(2-pyridylethyl)]amine, tris(2-pyridylmethyl)amine and 1,4-bis[2-(2-pyridylethyl)]piperazine

    Science.gov (United States)

    Mautner, Franz A.; Soileau, Jesse B.; Bankole, Paul K.; Gallo, August A.; Massoud, Salah S.

    2008-10-01

    Two classes of novel dicyanamido (dca)-Cu(II) complexes were synthesized with a variety of tetradentate tripod amines, tridentate amines and diazacycloalkanes with pyridyl arms of different alkyl lengths and with tetra-aza macrocycles with different cavity sizes; the mononuclear, Cu(L)(dca)]ClO 4 (L = tepa ( 1), TPA ( 2), pzdepy ( 4), hpzpy 2 ( 5), cyclen ( 7), cyclam ( 8), tacp ( 9)) or Cu(L)(dca)ClO 4 (L = MeDPA ( 10), Mepea ( 11)) and the dinuclear, [Cu 2(L') 2(dca)](ClO 4) 3 (L' = pmap ( 3), pzpy 2 ( 6)). The isolated complexes were structurally characterized by electronic and IR spectroscopy as well as by X-ray. Single crystal X-ray diffraction analysis of the complexes [Cu(tepa)(dca)]ClO 4 ( 1), [Cu(TPA)(dca)]ClO 4 ( 2) and [Cu(pzdepy)(dca)]ClO 4 ( 4) reveal their monomeric penta-coordinate nature with the isolated [Cu(L)(dca)] + cations and ClO4- counter ions. All the complexes with the exception of 2 adapt distorted square pyramidal geometry while the coordination polyhedron around the copper center in 2 may be described as a distorted trigonal bipyramidal stereochemistry. The visible spectra of the complexes in aqueous solutions or in methanol are in complete agreement with the assigned X-ray geometry around the Cu(II) centers.

  11. Redetermination of eveite, Mn2AsO4(OH, based on single-crystal X-ray diffraction data

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    Yongbo W. Yang

    2011-12-01

    Full Text Available The crystal structure of eveite, ideally Mn2(AsO4(OH [dimanganese(II arsenate(V hydroxide], was refined from a single crystal selected from a co-type sample from Långban, Filipstad, Varmland, Sweden. Eveite, dimorphic with sarkinite, is structurally analogous with the important rock-forming mineral andalusite, Al2OSiO4, and belongs to the libethenite group. Its structure consists of chains of edge-sharing distorted [MnO4(OH2] octahedra (..2 symmetry extending parallel to [001]. These chains are cross-linked by isolated AsO4 tetrahedra (..m symmetry through corner-sharing, forming channels in which dimers of edge-sharing [MnO4(OH] trigonal bipyramids (..m symmetry are located. In contrast to the previous refinement from Weissenberg photographic data [Moore & Smyth (1968. Am. Mineral. 53, 1841–1845], all non-H atoms were refined with anisotropic displacement parameters and the H atom was located. The distance of the donor and acceptor O atoms involved in hydrogen bonding is in agreement with Raman spectroscopic data. Examination of the Raman spectra for arsenate minerals in the libethenite group reveals that the position of the peak originating from the O—H stretching vibration shifts to lower wavenumbers from eveite, to adamite, zincolivenite, and olivenite.

  12. Cationic tungsten-oxo-alkylidene-N-heterocyclic carbene complexes: highly active olefin metathesis catalysts.

    Science.gov (United States)

    Schowner, Roman; Frey, Wolfgang; Buchmeiser, Michael R

    2015-05-20

    The synthesis, structure, and olefin metathesis activity of the first neutral and cationic W-oxo-alkylidene-N-heterocyclic carbene (NHC) catalysts are reported. Neutral W-oxo-alkylidene-NHC catalysts can be prepared in up to 90% isolated yield. Depending on the ligands used, they possess either an octahedral (Oh) or trigonal bipyramidal ligand sphere. They can be activated with excess AlCl3 to form cationic olefin metathesis-active W-complexes; however, these readily convert into neutral chloro-complexes. Well-defined, stable cationic species can be prepared by stoichiometric substitution of one chloro ligand in the parent, neutral W-oxo-alkylidene-NHC complexes with Ag(MeCN)2B(Ar(F))4 or NaB(Ar(F))4; B(Ar(F))4 = B(3,5-(CF3)2-C6H3)4. They are highly active olefin metathesis catalysts, allowing for turnover numbers up to 10,000 in various olefin metathesis reactions including alkenes bearing nitrile, sec-amine, and thioether groups.

  13. Cobalt(II), nickel(II), copper(II), and zinc(II) complexes with [3(5)]adamanzane, 1,5,9,13-tetraazabicyclo[7.7.3]nonadecane and [(2.3)(2).2(1)]adamanzane, 1,5,9,12-tetraazabicyclo[7.5.2]hexadecane

    DEFF Research Database (Denmark)

    Broge, Louise; Pretzmann, Ulla; Jensen, Nicolai

    2001-01-01

    Isolation of the free bicyclic tetraamine, [3(5)]adamanzane .H2O (1,5,9,13-tetraazabicyclo[7.7.3]nonadecane .H2O), is reported along with the synthesis and characterization of a copper(II) complex of the smaller macrocycle [(2.3)(2).2(1)]-adamanzane (1,5,9,12-tetraazabicyclo[7.5.2]hexadecane......) and of three cobalt(II), four nickel(II), one copper(II), and two zinc(II) complexes with [3(5)]adamanzane. For nine of these compounds (2-8, 10b, and 12) the single-crystal X-ray structures were determined. The coordination geometry around the metal ion is square pyramidal in [Cu([(2.3)(2).2(1)]adz)Br]ClO4 (2......) and trigonal bipyramidal in the isostructural structures [Cu([3(5)]adz)Br]Br (3), [Ni-([3(5)]adz)Cl]Cl (5), [Ni([3(5)]adz)Br]Br (6), and [Co([3(5)]adz)Cl]Cl (8). In [Ni([3(5)]adz)(NO3)]NO3 (4) and [Ni([3(5)]-adz)(ClO4)]ClO4 (7) the coordination geometry around nickel(II) is a distorted octahedron...

  14. Iminopyridine-Based Cobalt(II and Nickel(II Complexes: Synthesis, Characterization, and Their Catalytic Behaviors for 1,3-Butadiene Polymerization

    Directory of Open Access Journals (Sweden)

    Quanquan Dai

    2016-01-01

    Full Text Available A series of iminopyridine ligated Co(II (1a–7a and Ni(II (1b–7b complexes were synthesized. The structures of complexes 3a, 4a, 5a, 7a, 5b, and 6b were determined by X-ray crystallographic analyses. Complex 3a formed a chloro-bridged dimer, whereas 4a, 5a, and 7a, having a substituent (4a, 5a: CH3; 7a: Br at the 6-position of pyridine, producing the solid structures with a single ligand coordinated to the central metal. The nickel atom in complex 5b features distorted trigonal-bipyramidal geometry with one THF molecule ligating to the metal center. All the complexes activated by ethylaluminum sesquichloride (EASC were evaluated in 1,3-butadiene polymerization. The catalytic activity and selectivity were significantly influenced by the ligand structure and central metal. Comparing with the nickel complexes, the cobalt complexes exhibited higher catalytic activity and cis-1,4-selectivity. For both the cobalt and nickel complexes, the aldimine-based complexes showed higher catalyst activity than their ketimine counterparts.

  15. Chloridotris(pentafluorobenzenethiolato-κS[tris(4-fluorophenylphosphine-κP]osmium(IV

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    Asdrúbal Arias

    2010-04-01

    Full Text Available The title complex, [Os(C6F5S3Cl(C18H12F3P], displays a trigonal-bipyramidal OsIV coordination geometry with the S atoms of three thiolate ligands occupying the equatorial positions. The thiolate pentafluorophenyl substituents are all placed above the equatorial plane, forming a claw-like cavity which accommodates the chloride ligand with a normal Os—Cl bond length. The phosphine ligand trans to the chloride ligand reveals a short Os—P bond length compared to other chloride–phosphine OsIV complexes (average = 2.40 Å. This strong bonding indicates that the inductive effect of the F atoms in the phosphine does not affect significantly its basicity, compared to triphenylphosphine. This feature is also consistent with the known poor trans influence of Cl−. The crystal packing involves π–π contacts between inversion-related thiolate C6F5 rings, with a centroid–centroid separation of 3.659 (8 Å.

  16. The modulated structure of the calcium aluminate Ca6(AlO2)12·Bi2O3.

    Science.gov (United States)

    Pérez, O; Malo, S; Hervieu, M

    2010-12-01

    Bismuth calcium aluminate, Bi(2)Ca(6)Al(12)O(27), has been prepared as a ceramic and a single crystal. Analysis of reciprocal space using both electron and X-ray diffraction show an R-centred hexagonal unit cell: a = b = 17.3892 (4), c = 6.986 (1) Å. Additional weak reflections are observed; they require the introduction of a modulation wavevector q = 0.0453 (2)c* for indexing. The modulated structure has been solved using the superspace formalism [superspace group X3(00γ)0]. A framework of corner-sharing AlO(4) tetrahedra forms corrugated sixfold rings and uncommon triple rings. The Ca(2+) cations exhibit an eightfold coordination sphere; edge-sharing CaO(8) polyhedra form intertwinned zigzagging rows along c creating a three-dimensional net. Bi atoms are located in large hexagonal tunnels parallel to c and form Bi(2)O(3) pairs, which adopt a trigonal bipyramidal configuration. The 6s(2) lone-electron pairs (Lp) point along c, in the opposite direction to the three Bi-O strong bonds to form two BiO(3)Lp tetrahedra with a common base. Different orientations of the Bi(2)O(3)Lp(2) pairs, rotated by 60° around c, are observed. Their stacking modes in each of the hexagonal tunnels are described. The sequence of the stacking varies along c in each of the tunnels.

  17. Prioritization of charge over geometry in transition state analogues of a dual specificity protein kinase.

    Science.gov (United States)

    Xiaoxia, Liu; Marston, James P; Baxter, Nicola J; Hounslow, Andrea M; Yufen, Zhao; Blackburn, G Michael; Cliff, Matthew J; Waltho, Jonathan P

    2011-03-23

    The direct observation of a transition state analogue (TSA) complex for tyrosine phosphorylation by a signaling kinase has been achieved using (19)F NMR analysis of MEK6 in complex with tetrafluoroaluminate (AlF(4)(-)), ADP, and p38α MAP kinase (acceptor residue: Tyr182). Solvent-induced isotope shifts and chemical shifts for the AlF(4)(-) moiety indicate that two fluorine atoms are coordinated by the two catalytic magnesium ions of the kinase active site, while the two remaining fluorides are liganded by protein residues only. An equivalent, yet distinct, AlF(4)(-) complex involving the alternative acceptor residue in p38α (Thr180) is only observed when the Tyr182 is mutated to phenylalanine. The formation of octahedral AlF(4)(-) species for both acceptor residues, rather than the trigonal bipyramidal AlF(3)(0) previously identified in the only other metal fluoride complex with a protein kinase, shows the requirement of MEK6 for a TSA that is isoelectronic with the migrating phosphoryl group. This requirement has hitherto only been demonstrated for proteins having a single catalytic magnesium ion.

  18. Substitutional disorder in the ionic diorganoantimony halide adduct [bromido/chlorido(0.33/0.67][2-(dimethylaminomethylphenyl][2-(dimethylammoniomethylphenyl]antimony(III 0.75-bromide 0.25-chloride

    Directory of Open Access Journals (Sweden)

    Albert P. Soran

    2010-04-01

    Full Text Available The title complex, [SbBr0.33Cl0.67(C9H13N(C9H12N]Br0.75Cl0.25, exhibits substitutional disorder of both halogen atoms in the asymmetric unit, however, with different occupancies. Thus, the halogen atom bonded to Sb has 0.67 (4 occupancy for Cl and 0.33 (4 for Br, while the anionic halogen atom shows 0.75 (4 occupancy for Br and 0.25 (4 for Cl. An N—H...Cl/Br hydrogen bond is established between the cation and the halide anion. The coordination geometry of the Sb center in the cation is distorted pseudo-trigonal-bipyramidal as a result of the strong intramolecular N→Sb coordination trans to the Sb—Cl/Br bond. The pendant arm on the second ligand is twisted away from the metal center. The compound crystallizes as a racemate, i.e. a mixture of (RN2,CSb1 and (SN2,ASb1 isomers with respect to planar chirality induced by the coordinating N atom and chelate-induced Sb chirality. These isomers are associated through Cphenyl—H...Cl/Br hydrogen bonds, forming a three-dimensional architecture.

  19. Molecular structure, supramolecular association and anion sensing by chlorodiorganotin(IV) methylferrocenyldithiocarbamates

    Science.gov (United States)

    Yadav, Reena; Awasthi, Mahendra Kumar; Singh, Amita; Kociok-Köhn, Gabriele; Trivedi, Manoj; Prasad, Rajendra; Shahid, Mohammad; Kumar, Abhinav

    2017-10-01

    Three new chlorodiorganotin(IV) methylferrocenyl dithiocarbamate complexes viz. [(FcCH2)(CH2CH2OH)NCS2SnMe2(Cl)] (1), [(FcCH2)(CH2CH2OH)NCS2SnnBu2(Cl)] (2) and [(FcCH2)(CH2CH2OH)NCS2SnPh2(Cl)] (3) have been synthesized and characterized by elemental analysis, IR, UV-Vis, 1H, 13C and 119Sn NMR spectroscopy and X-ray crystallography. The crystal structure of 1 indicates that the coordination geometries around the tin(IV) center is intermediate between ideal trigonal-bipyramidal and square pyramidal coordination polyhedra bonded through two sulfur atoms of the dithiocarbamate ligand in an isobidentate mode, two CH3 groups and one chlorine atom. Since, in 2 and 3 only alkyl and aryl fragments have been changed we infer that both 2 and 3 would also have the same behaviors in the solution state as observed in 1. Ionic interactions abilities of 1-3 are examined in acetonitrile through UV-vis absorption spectroscopy which offers reasonably good selectivity and sensitivity towards the detection of the acetate ion. Compounds 1-3 exhibit a bathochromic shift with the acetate ion with a moderate association constant.

  20. Cobalt (III) complexes as novel matrix metalloproteinase-9 inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jiyoun [Sungshin Women' s Univ., Seoul (Korea, Republic of)

    2012-04-15

    We have synthesized a series of novel MMP-9 inhibitors containing cobalt(III) complexes. The synthesized cobalt(III) complexes are effective as enzyme inhibitors and the attachment of a biphenyl group enhanced the efficiency of enzyme inhibition up to 6-fold. When compared to the reported non-hydroxamate MMP inhibitors, the synthesized complexes showed comparable in vitro potency. The enzyme assay showed that the cobalt(III) complex can disrupt the zinc binding active site of MMP-9 and is proposed to work via a ligand exchange mechanism. Since histidine residues are essential for the catalytic activity of a large percentage of enzymes and zinc finger proteins, these cobalt(III) complexes can serve as a prototype inhibitor towards various zinc containing enzymes and proteins. Matrix metalloproteinases (MMPs) are a family of zinc binding endopeptidases that play crucial roles in various physiological processes and diseases such as embryogenic growth, angiogenesis, arthritis, skin ulceration, liver fibrosis and tumor metastasis. Because of their implications in a wide range of diseases, MMPs are considered as intriguing drug targets. The majority of MMP inhibitors are organic small molecules containing a hydroxamate functionality for the zinc binding group. This hydroxamate group binds to a zinc(II) center in a bidentate fashion and creates a distorted trigonal bipyramidal geometry.

  1. Design of a Binuclear Ni(II) Complex with Large Ising-type Anisotropy and Weak Anti-Ferromagnetic Coupling.

    Science.gov (United States)

    El-Khatib, Fatima; Cahier, Benjamin; López-Jordà, Maurici; Guillot, Régis; Rivière, Eric; Hafez, Hala; Saad, Zeinab; Girerd, Jean-Jacques; Guihéry, Nathalie; Mallah, Talal

    2017-09-05

    The preparation of a binuclear Ni(II) complex with a pentacoordinate environment using a cryptand organic ligand and the imidazolate bridge is reported. The coordination sphere is close to trigonal bipyramidal (tbp) for one Ni(II) and to square pyramidal (spy) for the other. The use of the imidazolate bridge that undergoes π-π stacking with two benzene rings of the chelating ligand induces steric hindrance that stabilizes the pentacoordinate environment. Magnetic measurements together with theoretical studies of the spin states energy levels allow fitting the data and reveal a large Ising-type anisotropy and a weak anti-ferromagnetic exchange coupling between the metal ions. The magnitude and the nature of the magnetic anisotropy and the difference in anisotropy between the two metal ions are rationalized using wave-function-based calculations. We show that a slight distortion of the coordination sphere of Ni(II) from spy to tbp leads to an Ising-type anisotropy. Broken-symmetry density functional calculations rationalize the weak anti-ferromagnetic exchange coupling through the imidazolate bridge.

  2. Crystal structure of 4,8-di-tert-butyl-6,6-dichloro-13-ethyl-2,10-dimethyl-13,14-dihydro-12H-dibenzo[d,i][1,3,7,2]dioxazasilecine toluene 0.25-solvate

    Directory of Open Access Journals (Sweden)

    Ekaterina A. Kuchuk

    2015-12-01

    Full Text Available The coordination polyhedron at the silicon atom in the title compound, C26H37Cl2NO2Si·0.25C7H8, is typical for pentacoordinated silicon derivatives and represents a slightly distorted trigonal bipyramid with an N atom and a Cl atom in the apical positions and the two O atoms and the other Cl atom occupying the equatorial sites. There are two independent molecules in the asymmetric unit. The N–Si–Cl fragment in each is close to linear [178.24 (5 and 178.71 (5°], in good agreement with 4e–3c theory, as is the elongation of the apical bond lengths [Si—Cl = 2.1663 (7 and 2.1797 (7 Å] in comparison with the equatorial bonds [Si—Cl = 2.0784 (7 and 2.0748 (7 Å]. Orthogonal least-squares fitting of the two independent molecules resulted in r.m.s. deviation of 0.017 Å. The conformations of the two molecules are almost the same, with corresponding torsion angles differing by less than 5.5°. The toluene solvent molecule is disordered about an inversion centre.

  3. Poly[μ-aqua-diaqua(μ2-pyrazine-2,3-dicarboxylatodilithium(I

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    Kutalmis Guven

    2009-12-01

    Full Text Available The asymmetric unit of the title compound, [Li2(C6H2N2O4(H2O3]n, consists of two independent Li+ cations, one pyrazine-2,3-dicarboxylate dianion and three water molecules. One of the Li+ cations has a distorted tetrahedral geometry, coordinated by one of the carboxylate O atoms of the pyrazine-2,3-dicarboxylate ligand and three O atoms from three water molecules, whereas the other Li+ cation has a distorted trigonal-bipyramidal geometry, coordinated by a carboxylate O atom of a symmetry-related pyrazine-2,3-dicarboxylate ligand, two water molecules and a chelating pyrazine-2,3-dicarboxylate ligand (by utilizing both N and O atoms of an adjacent molecule. The synthesis of a hydrated polymeric dinuclear lithium complex formed with two pyrazine-2,3-dicarboxylic acid ligands has been reported previously [Tombul et al. (2008a. Acta Cryst. E64, m491–m492]. By comparision to the complex reported here, the dinuclear complex formed with two pyrazine-2,3-dicarboxylic acid ligands differs in the coordination geometry of both Li atoms. The crystal structure further features O—H...O and O—H...N hydrogen-bonding interactions involving the water molecules and carboxylate O atoms.

  4. Tetra-, Penta- and Hexa-Coordinated Transition Metal Complexes Constructed from Coumarin-Containing N2O2 Ligand

    Directory of Open Access Journals (Sweden)

    Lei Gao

    2018-02-01

    Full Text Available Three newly designed complexes, [Cu(L]·CHCl3 (1, [Co(L(MeOH]·CHCl3 (2 and [{Ni(L(MeOH(PhCOO}2Ni] (3 a coumarin-containing Salamo-type chelating ligand (H2L have been synthesized and characterized by elemental analyses, IR and UV-VIS spectra, and X-ray crystallography. Complex 1 includes one Cu(II atom, one completely deprotonated (L2− unit and one crystalling chloroform molecule, the Cu(II atom shows a square-planar geometry. Complex 2 includes one Co(II atom, one completely deprotonated (L2− unit, one coordinated methanol molecule and one crystalling chloroform molecule. The Co(II atom is a distorted trigonal-bipyramidal geometry. While complex 3 includes three Ni(II atoms, two completely deprotonated (L2− units, two benzoates and two coordinated methanol molecules. The complexes 1 and 2 are both possess three-dimensional supra-molecular structures by abundant noncovalent interactions. But, complex 3 formed a two-dimensional supra-molecular structure by intra-molecular hydrogen bonds. In addition, the antimicrobial and fluorescence properties of H2L and its complexes 1, 2 and 3 were also investigated.

  5. Crystal structure of (4,4′-bipyridyl-κNbis[N-(2-hydroxyethyl-N-isopropyldithiocarbamato-κ2S,S′]zinc(II–4,4′-bipyridyl (2/1 and its isostructural cadmium(II analogue

    Directory of Open Access Journals (Sweden)

    Yee Seng Tan

    2017-11-01

    Full Text Available The title structures, [M(C6H12NOS22(C10H8N2]·0.5C10H8N2, for M = Zn, (I, and Cd, (II, feature terminally bound 4,4′-bipyridyl ligands and non-coordinating 4,4′-bipyridyl molecules, with the latter disposed about a centre of inversion. The coordination geometry about the metal atom is defined by two non-symmetrically chelating dithiocarbamate ligands and a pyridyl N atom. The NS4 donor sets are distorted but, approximate to trigonal bipyramidal in each case. In the crystal, hydroxy-O—H...O(hydroxy and hydroxy-O—H...N(pyridyl hydrogen bonds between the zinc-containing molecules lead to a supramolecular layer parallel to (100. The three-dimensional architecture arises as the layers are linked via methine-C—H...S, pyridyl-C—H...O(hydroxy and π–π [inter-centroid distance between coordinated pyridyl rings = 3.6246 (18 Å] interactions. Channels along the c-axis direction are occupied by the non-coordinating 4,4′-bipyridine molecules, which are held in place by C—H...π(chelate ring contacts.

  6. Interplay of bifurcated hydrogen bonds in making of inclusion/pseudo-inclusion complexes of Ni(II), Cu(II) and Zn(II) of a salophen type ligand: Crystal structures and spectral aspects

    Science.gov (United States)

    Ambili, K. U.; Sithambaresan, M.; Kurup, M. R. Prathapachandra

    2017-04-01

    Three novel photoluminescent materials were synthesized by treating Ni(II), Cu(II) and Zn(II) acetate salts with a Schiff base prepared from 3-ethoxysalicylaldehyde and 2-aminobenzylamine. Among the prepared complexes, Ni(II) and Cu(II) complexes are inclusion compounds while Zn(II) complex is a pseudo-inclusion compound. They were characterized by elemental analysis, IR, UV-visible and EPR spectra. Single crystal XRD studies of these complexes suggest that Ni(II) and Cu(II) are in a distorted square planar environment while the spatial arrangement of donor atoms in Zn(II) complex is best described as distorted square based pyramid although significant distortion towards trigonal bipyramid is noticed. Stabilized crystal packing of the complexes is established via supramolecular interactions. The metal chelate rings as the π system for C-H···π interactions found in Cu(II) and Zn(II) complexes explicit the concept of metalloaromaticity. TG-DTG studies reveal that all the complexes are thermally stable. Both ligand and complexes exhibit intense photoluminescence in near UV region. However, Zn(II) complex giving an intense blue-green emission spectrum at maximum wavelength of 518 nm with shoulder peaks, could be used for optoelectronic applications.

  7. Octabutylbis(μ2-2-chloro-5-nitrobenzoatobis(2-chloro-5-nitrobenzoatodi-μ3-oxido-tetratin(IV

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    Hoong-Kun Fun

    2010-12-01

    Full Text Available The title complex, [Sn4(C4H98(C7H3ClNO44O2], is a cluster formed by a crystallographic inversion center around the central Sn2O2 ring. Both of the two independent Sn atoms are five-coordinated, with distorted trigonal–bipyramidal SnC2O3 geometries. One Sn atom is coordinated by two butyl groups, one O atom of the benzoate anion and two bridging O atoms, whereas the other Sn atom is coordinated by two butyl groups, two O atoms of the benzoate anions and a bridging O atom. The O atoms of the bridging benzoate anion are disordered over two sites with an occupancy ratio of 0.862 (12:0.138 (12. One of the butyl groups coordinated to the Sn2O2 ring is disordered over two sites with an occupancy ratio of 0.780 (8:0.220 (8, whereas both of the two butyl groups coordinated to the other Sn atom are disordered over two sites with occupancy ratios of 0.788 (5:0.212 (5 and 0.827 (10:0.173 (10. All the butyl groups are equatorial with respect to the SnO3 trigonal plane. In the crystal, complex molecules are stacked down [010] with weak intermolecular C—H...π interactions stabilizing the crystal structure.

  8. A Crystal Field Approach to Orbitally Degenerate SMMs: Beyond the Spin-Only Hamiltonian

    Science.gov (United States)

    Bhaskaran, Lakshmi; Marriott, Katie; Murrie, Mark; Hill, Stephen

    Single-Molecule Magnets (SMMs) with large magnetization reversal barriers are promising candidates for high-density information storage. Recently, a large uniaxial magnetic anisotropy was observed for a mononuclear trigonal bipyramidal (TBP) [NiIICl3(Me-abco)2] SMM. High-field EPR studies analyzed on the basis of a spin-only Hamiltonian give ¦D¦>400 cm-1, which is close to the spin-orbit coupling parameter λ = 668 cm-1 for NiII, suggesting an orbitally degenerate ground state. The spin-only description is ineffective in this limit, necessitating the development of a model that includes the orbital moment. Here we describe a phenomenological approach that takes into account a full description of crystal field, electron-electron repulsion and spin-orbit coupling effects on the ground state of a NiII ion in a TBP coordination geometry. The model is in good agreement with the high-field EPR experiments, validating its use for spectroscopic studies of orbitally degenerate molecular nanomagnets. This work was supported by the NSF (DMR-1309463).

  9. Robertsite, Ca2MnIII3O2(PO43·3H2O

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    Marcelo B. Andrade

    2012-10-01

    Full Text Available Robertsite, ideally Ca2Mn3O2(PO43·3H2O [calcium manganese(III tris(orthophosphate trihydrate], can be associated with the arseniosiderite structural group characterized by the general formula Ca2A3O2(TO43·nH2O, with A = Fe, Mn; T = As, P; and n = 2 or 3. In this study, single-crystal X-ray diffraction data were used to determine the robertsite structure from a twinned crystal from the type locality, the Tip Top mine, Custer County, South Dakota, USA, and to refine anisotropic displacement parameters for all atoms. The general structural feature of robertsite resembles that of the other two members of the arseniosiderite group, the structures of which have previously been reported. It is characterized by sheets of [MnO6] octahedra in the form of nine-membered pseudo-trigonal rings. Located at the center of each nine-membered ring is a PO4 tetrahedron, and the other eight PO4 tetrahedra sandwich the Mn–oxide sheets. The six different Ca2+ ions are seven-coordinated in form of distorted pentagonal bipyramids, [CaO5(H2O2], if Ca—O distances less than 2.85 Å are considered. Along with hydrogen bonding involving the water molecules, they hold the manganese–phosphate sheets together. All nine [MnO6] octahedra are distorted by the Jahn–Teller effect.

  10. Novel Organotin(IV) Schiff Base Complexes with Histidine Derivatives: Synthesis, Characterization, and Biological Activity

    Science.gov (United States)

    Garza-Ortiz, Ariadna; Camacho-Camacho, Carlos; Sainz-Espuñes, Teresita; Rojas-Oviedo, Irma; Gutiérrez-Lucas, Luis Raúl; Gutierrez Carrillo, Atilano; Vera Ramirez, Marco A.

    2013-01-01

    Five novel tin Schiff base complexes with histidine analogues (derived from the condensation reaction between L-histidine and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) have been synthesized and characterized. Characterization has been completed by IR and high-resolution mass spectroscopy, 1D and 2D solution NMR (1H, 13C  and 119Sn), as well as solid state 119Sn NMR. The spectroscopic evidence shows two types of structures: a trigonal bipyramidal stereochemistry with the tin atom coordinated to five donating atoms (two oxygen atoms, one nitrogen atom, and two carbon atoms belonging to the alkyl moieties), where one molecule of ligand is coordinated in a three dentate fashion. The second structure is spectroscopically described as a tetrahedral tin complex with four donating atoms (one oxygen atom coordinated to the metal and three carbon atoms belonging to the alkyl or aryl substituents), with one molecule of ligand attached. The antimicrobial activity of the tin compounds has been tested against the growth of bacteria in vitro to assess their bactericidal properties. While pentacoordinated compounds 1, 2, and 3 are described as moderate effective to noneffective drugs against both Gram-positive and Gram-negative bacteria, tetracoordinated tin(IV) compounds 4 and 5 are considered as moderate effective and most effective compounds, respectively, against the methicillin-resistant Staphylococcus aureus strains (Gram-positive). PMID:23864839

  11. Crystal structure of the cambialistic superoxide dismutase from Aeropyrum pernix K1--insights into the enzyme mechanism and stability.

    Science.gov (United States)

    Nakamura, Tsutomu; Torikai, Kasumi; Uegaki, Koichi; Morita, Junji; Machida, Kodai; Suzuki, Atsushi; Kawata, Yasushi

    2011-02-01

    Aeropyrum pernix K1, an aerobic hyperthermophilic archaeon, produces a cambialistic superoxide dismutase that is active in the presence of either of Mn or Fe. The crystal structures of the superoxide dismutase from A. pernix in the apo, Mn-bound and Fe-bound forms were determined at resolutions of 1.56, 1.35 and 1.48 Å, respectively. The overall structure consisted of a compact homotetramer. Analytical ultracentrifugation was used to confirm the tetrameric association in solution. In the Mn-bound form, the metal was in trigonal bipyramidal coordination with five ligands: four side chain atoms and a water oxygen. One aspartate and two histidine side chains ligated to the central metal on the equatorial plane. In the Fe-bound form, an additional water molecule was observed between the two histidines on the equatorial plane and the metal was in octahedral coordination with six ligands. The additional water occupied the postulated superoxide binding site. The thermal stability of the enzyme was compared with superoxide dismutase from Thermus thermophilus, a thermophilic bacterium, which contained fewer ion pairs. In aqueous solution, the stabilities of the two enzymes were almost identical but, when the solution contained ethylene glycol or ethanol, the A. pernix enzyme had significantly higher thermal stability than the enzyme from T. thermophilus. This suggests that dominant ion pairs make A. pernix superoxide dismutase tolerant to organic media. © 2010 The Authors Journal compilation © 2010 FEBS.

  12. Can a hydroxide ligand trigger a change in the coordination number of magnesium ions in biological systems?

    Science.gov (United States)

    Kluge, Stefan; Weston, Jennie

    2005-03-29

    Density functional (B3LYP) calculations indicate that a hydroxide ligand is capable of triggering a reduction in the coordination number of Mg(2+) ions from 6 to 5. Since this could be quite relevant in the mode of action of magnesium-containing enzymes (especially hydrolases in which a metal-bound hydroxide species is believed to play a crucial role), we have performed a systematic deprotonation study of biologically relevant magnesium complexes. We explicitly calculated the preferred coordination number of [MgL(1)(x)L(2)(y)L(3)(z)](2)(-)(n) species at the B3LYP/aug-cc-pVTZ level of theory. L(1), L(2), and L(3) represent combinations of water, hydroxide, carboxylate (models Glu and Asp), ammonia ligands (models Lys and His residues), and fluoride ions. As expected, Mg(2+) exclusively prefers an octahedral coordination geometry with H(2)O, HCO(2)(-), or NH(3). Surprisingly, one hydroxide ligand triggers a change to a trigonal bipyramidal geometry. The isoelectronic fluoride ion behaves similarly. When two OH(-) are present, a tetrahedral coordination geometry is preferred. We postulate that a hydroxide (in addition to its role as an active nucleophile) could be employed by magnesium-containing enzymes to trigger a differential coordination behavior.

  13. Degenerate nucleophilic substitution in phosphonium salts.

    Science.gov (United States)

    Jennings, Elizabeth V; Nikitin, Kirill; Ortin, Yannick; Gilheany, Declan G

    2014-11-19

    Rates and energy barriers of degenerate halide substitution on tetracoordinate halophosphonium cations have been measured by NMR techniques (VT and EXSY) using a novel experimental design whereby a chiral substituent ((s)Bu) lifts the degeneracy of the resultant salts. Concomitantly, a viable computational approach to the system was developed to gain mechanistic insights into the structure and relative stabilities of the species involved. Both approaches strongly suggest a two-step mechanism of formation of a pentacoordinate dihalophosphorane via backside attack followed by dissociation, resulting in inversion of configuration at phosphorus. The experimentally determined barriers range from salts. Calculations determined that this was due to the easier accessibility in solution of pentacoordinate dichlorophosphoranes when compared to analogous dibromophosphoranes. In line with the proposed associative mechanism, bulky substituents slow the reaction in the order Me < Et < (i)Pr < (t)Bu. Bulky substituents affect the shape of the reaction energy profile so that the pentacoordinate intermediate is destabilized eventually becoming a transition state. The magnitude of the steric effects is comparable to that of the same substituents on substitution at primary alkyl halides, which can be rationalized by the relatively longer P-C bonds. The reaction displays first-order kinetics due to the prevalence of tight- or solvent-separated ion pairs in solution. Three-dimensional reaction potential energy profiles (More O'Ferrall-Jencks plots) indicated a relatively shallow potential well corresponding to the trigonal bipyramid intermediate flanked by two transition states.

  14. Bis(N,N-diethyldithiocarbamato-κ2S,S′(3-hydroxypyridine-κNzinc and bis[N-(2-hydroxyethyl-N-methyldithiocarbamato-κ2S,S′](3-hydroxypyridine-κNzinc: crystal structures and Hirshfeld surface analysis

    Directory of Open Access Journals (Sweden)

    Mukesh M. Jotani

    2016-12-01

    Full Text Available The common feature of the molecular structures of the title compounds, [Zn(C5H10NS22(C5H5NO], (I, and [Zn(C4H8NOS22(C5H5NO], (II, are NS4 donor sets derived from N-bound hydroxypyridyl ligands and asymmetrically chelating dithiocarbamate ligands. The resulting coordination geometries are highly distorted, being intermediate between square pyramidal and trigonal bipyramidal for both independent molecules comprising the asymmetric unit of (I, and significantly closer towards square pyramidal in (II. The key feature of the molecular packing in (I is the formation of centrosymmetric, dimeric aggregates sustained by pairs of hydroxy-O—H...S(dithiocarbamate hydrogen bonds. The aggregates are connected into a three-dimensional architecture by methylene-C—H...O(hydroxy and methyl-C—H...π(chelate interactions. With greater hydrogen-bonding potential, supramolecular chains along the c axis are formed in the crystal of (II, sustained by hydroxy-O—H...O(hydroxy hydrogen bonds, with ethylhydroxy and pyridylhydroxy groups as the donors, along with ethylhydroxy-O—H...S(dithiocarbamate hydrogen bonds. Chains are connected into layers in the ac plane by methylene-C—H...π(chelate interactions and these stack along the b axis, with no directional interactions between them. An analysis of the Hirshfeld surfaces clearly distinguished the independent molecules of (I and reveals the importance of the C—H...π(chelate interactions in the packing of both (I and (II.

  15. Crystal structures of {μ2-N,N′-bis[(pyridin-3-ylmethyl]ethanediamide}tetrakis(dimethylcarbamodithioatodizinc(II dimethylformamide disolvate and {μ2-N,N′-bis[(pyridin-3-ylmethyl]ethanediamide}tetrakis(di-n-propylcarbamodithioatodizinc(II

    Directory of Open Access Journals (Sweden)

    Hadi D. Arman

    2017-10-01

    Full Text Available The title structures, [Zn2(C3H6NS24(C14H14N4O2]·2C3H7NO (I and [Zn2(C7H14NS24(C14H14N4O2] (II, each feature a bidentate, bridging bipyridyl-type ligand encompassing a di-amide group. In (I, the binuclear compound is disposed about a centre of inversion, leading to an open conformation, while in (II, the complete molecule is completed by the application of a twofold axis of symmetry so that the bridging ligand has a U-shape. In each of (I and (II, the dithiocarbamate ligands are chelating with varying degrees of symmetry, so the zinc atom is within an NS4 set approximating a square-pyramid for (I and a trigonal-bipyramid for (II. The solvent dimethylformaide (DMF molecules in (I connect to the bridging ligand via amide-N—H...O(DMF and various amide-, DMF-C—H...O(amide, DMF interactions. The resultant three-molecule aggregates assemble into a three-dimensional architecture via C—H...π(pyridyl, chelate ring interactions. In (II, undulating tapes sustained by amide-N—H...O(amide hydrogen bonding lead to linear supramolecular chains with alternating molecules lying to either side of the tape; no further directional interactions are noted in the crystal.

  16. Five-Coordinate Zinc(II Complex: Synthesis, Characterization, Molecular Structure, and Antibacterial Activities of Bis-[(E-2-hydroxy-N′-{1-(4-methoxyphenylethylidene}benzohydrazido]dimethylsulfoxidezinc(II Complex

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    Zhi-Qiang Liu

    2017-01-01

    Full Text Available The titled Zn(II complex was synthesized by reacting the compound (E-2-hydroxy-N′-{1-(4-methoxyphenylethylidene}benzohydrazide with zinc(II acetate dihydrate in alkaline DMSO and ethanol solution under reflux condition for 28 hours. The resulting solid was filtered and recrystallized from the mixture of ethanol and DMSO. The hydrazone Schiff base and its Zn(II complex were characterized using 1H, 13C NMR, FTIR, UV-Vis spectroscopy, and single crystal X-ray diffraction analysis. Meanwhile, their antibacterial activities were examined using disc diffusion method. The spectral studies showed that the hydrazone Schiff base underwent keto-enol tautomerization, forming a bidentate ligand (N,O towards Zn(II ion. Surprisingly, on top of the two hydrazone Schiff base molecules which coordinated to the Zn metal center, an additional DMSO molecule was found attached to the Zn metal center in the crystal data, resulting in a 5-coordinate distorted trigonal bipyramidal Zn(II complex. Both hydrazone Schiff base and its Zn(II complexes were found to exhibit low antibacterial activity even when the concentrations were increased to 800 ppm.

  17. Photostabilizing Efficiency of Poly(vinyl chloride in the Presence of Organotin(IV Complexes as Photostabilizers

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    Mustafa M. Ali

    2016-08-01

    Full Text Available Three organotin complexes containing furosemide as a ligand (L, Ph3SnL, Me2SnL2 and Bu2SnL2, were synthesized and characterized. Octahedral geometry was proposed for the Me2SnL2 and Bu2SnL2, while the Ph3SnL complex has trigonal bipyramid geometry. The synthesized organotin complexes (0.5% by weight were used as additives to improve the photostability of poly(vinyl chloride, PVC, (40 μm thickness upon irradiation. The changes imposed on functional groups, weight loss and viscosity average molecular weight of PVC films were monitored. The experimental results show that the rate of photodegradation was reduced in the presence of the organotin additives. The quantum yield of the chain scission was found to be low (9.8 × 10−7 when Ph3SnL was used as a PVC photostabilizer compared to controlled PVC (5.18 × 10−6. In addition, the atomic force microscope images for the PVC films containing Ph3SnL2 after irradiation shows a smooth surface compared to the controlled films. The rate of PVC photostabilization was found to be highest for Ph3SnL followed by Bu2SnL2 and Me2SnL2. It has been suggested that the organotin complexes could act as hydrogen chloride scavengers, ultraviolet absorbers, peroxide decomposers and/or radical scavengers.

  18. A novel iron complex containing an N,O-type bidentate oxazoline ligand: Synthesis, X-ray studies, DFT calculations and catalytic activity.

    Science.gov (United States)

    Amini, Mojtaba; Arab, Ali; Derakhshandeh, Parviz Gohari; Bagherzadeh, Mojtaba; Ellern, Arkady; Woo, L Keith

    2014-12-10

    A five-coordinated Fe(III) complex with the distorted trigonal bipyramidal configuration was synthesized by reactions of FeCl3⋅6H2O and 2-(2'-hydroxyphenyl)oxazoline (Hphox) as a bidentate ON donor oxazoline ligand. Complex [Fe(phox)2Cl] was fully characterized, including by single-crystal X-ray structure analysis. DFT calculations were accompanied with experimental results in order to obtain a deeper insight into the electronic structure and vibrational normal modes of complex. Oxidation of sulfides to sulfoxides in one-step was conducted by this complex as catalyst using urea hydrogen peroxide (UHP) in mixture of CH2Cl2/CH3OH (1:1) under air at room temperature. The results show that using this system in oxidation of sulfides, sulfoxides are obtained as the main products, together with variable amounts of sulfones (≤13%), depending on the nature of the substrate. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. A new oxovanadium(IV) complex containing an O,N-bidentate Schiff base ligand: Synthesis at ambient temperature, characterization, crystal structure and catalytic performance in selective oxidation of sulfides to sulfones using H2O2 under solvent-free conditions

    Science.gov (United States)

    Menati, Saeid; Rudbari, Hadi Amiri; Khorshidifard, Mahsa; Jalilian, Fariba

    2016-01-01

    A new bidentate ON Schiff base ligand, HL, was synthesized by simple condensation reaction of isopropylamine and salicylaldehyde. Then by reaction of HL and VO(acac)2 in the ratio of 2:1 at ambient temperature, a new oxovanadium(IV) Schiff base complex, VOL2, was synthesized. The Schiff base ligand and its oxovanadium(IV) complex were characterized by elemental analyses, FT-IR, 1H NMR, 13C NMR and UV-visible spectroscopies. The crystal structure of oxovanadium(IV) complex, VOL2, was also determined by single crystal X-ray analysis. The vanadium center in this structure is coordinated to two bidentate Schiff base ligands with the two nitrogen and two phenolate oxygen atoms in equatorial positions and one oxo oxygen in the axial position to complete the distorted trigonal bipyramidal N2O3 coordination sphere. Catalytic performance of the VOL2 complex was studied in the selective oxidation of thioanisole with the green oxidant 35% aqueous H2O2 under solvent-free conditions and under organic solvents (EtOH, CHCl3, CH2Cl2, DMF, CH3CN, EtOAc) as a model. Due to better catalytic performance of the VOL2 complex under solvent-free conditions, this complex used for the oxidation of the different sulfides to the corresponding sulfones under solvent-free conditions. The use of hydrogen peroxide as oxidant and the absence of solvent makes these reactions interesting from environmental and economic points of view.

  20. Theoretical Prediction of Surface Stability and Morphology of LiNiO2Cathode for Li Ion Batteries.

    Science.gov (United States)

    Cho, Eunseog; Seo, Seung-Woo; Min, Kyoungmin

    2017-09-27

    Ni-rich layered oxides are considered to be a promising cathode material with high capacity, and their surface structure should be extensively explored to understand the complex associated phenomena. We investigated the surface stability and morphology of LiNiO 2 as a representative of these materials by using density functional theory calculations. The results reveal that the Li-exposed surfaces have lower energies than the oxygen surfaces, irrespective of the facets, and the Ni-exposed ones are the least stable. The equilibrium morphology can vary from truncated trigonal bipyramid to truncated egg shape, according to the chemical potential, whose range is confined by the phase diagram. Moreover, the electrochemical window of stable facets is found to strongly depend on the surface elements rather than the facet directions. Contrary to the stable Li surfaces, oxygen exposure on the surface considerably lowers the Fermi level to the level of electrolyte, thereby accelerating oxidative decomposition of the electrolyte on the cathode surface.

  1. The crystal structure of tryptophan hydroxylase with bound amino acid substrate

    DEFF Research Database (Denmark)

    Windahl, Michael Skovbo; Petersen, Charlotte Rode; Christensen, Hans Erik Mølager

    2008-01-01

    Tryptophan hydroxylase (TPH) is a mononuclear non-heme iron enzyme, which catalyzes the reaction between tryptophan, O2, and tetrahydrobiopterin (BH4) to produce 5-hydroxytryptophan and 4a-hydroxytetrahydrobiopterin. This is the first and rate-limiting step in the biosynthesis of the neurotransmi......Tryptophan hydroxylase (TPH) is a mononuclear non-heme iron enzyme, which catalyzes the reaction between tryptophan, O2, and tetrahydrobiopterin (BH4) to produce 5-hydroxytryptophan and 4a-hydroxytetrahydrobiopterin. This is the first and rate-limiting step in the biosynthesis...... of the neurotransmitter and hormone serotonin (5-hydroxytryptamine). We have determined the 1.9 Å resolution crystal structure of the catalytic domain (Δ1−100/Δ415−445) of chicken TPH isoform 1 (TPH1) in complex with the tryptophan substrate and an iron-bound imidazole. This is the first structure of any aromatic amino...... acid hydroxylase with bound natural amino acid substrate. The iron coordination can be described as distorted trigonal bipyramidal coordination with His273, His278, and Glu318 (partially bidentate) and one imidazole as ligands. The tryptophan stacks against Pro269 with a distance of 3.9 Å between...

  2. Stereochemical diversity of {MNO}(10) complexes: molecular orbital analyses of nickel and copper nitrosyls.

    Science.gov (United States)

    Conradie, Jeanet; Ghosh, Abhik

    2014-05-19

    The great majority of {NiNO}(10) complexes are characterized by short Ni-N(O) distances of 1.60-1.65 Å and linear NO units. Against this backdrop, the {CuNO}(10) unit in the recently reported [Cu(CH3NO2)5(NO)](2+) cation (1) has a CuNO angle of about 120° and a very long 1.96 Å Cu-N(O) bond. According to DFT calculations, metal-NO bonding in 1 consists of a single Cu(dz(2))-NO(π*) σ-interaction and essentially no metal(dπ)-NO(π*) π-bonding, which explains both the bent CuNO geometry and the long, weak Cu-N(O) bond. This σ-interaction is strongly favored by a ligand trans to the NO; indeed such a trans ligand may be critical for the existence and stability of a {CuNO}(10) unit. By contrast, {NiNO}(10) complexes exhibit a strong avoidance of such trans ligands. Thus, a five-coordinate {NiNO}(10) complex appears to favor a trigonal-bipyramidal structure with the NO in an equatorial position, as in the case of [Ni(bipy)2(NO)](+) (6). An unusual set of Ni(d)-NO(π*) orbital interactions accounts for the strongly bent NiNO geometry for this complex.

  3. Coordination chemistry of Co complexes containing tridentate SNS ligands and their application as catalysts for the oxidation of n-octane.

    Science.gov (United States)

    Soobramoney, Lynette; Bala, Muhammad D; Friedrich, Holger B

    2014-11-14

    The selective oxidation of saturated hydrocarbons to terminal oxygenates under mild catalytic conditions has remained a centuries long challenge in chemical catalysis. In an attempt to address this challenge, two series of tridentate donor ligands {2,6-bis(RSCH2)pyridine and bis(RSCH2CH2)amine [R = alkyl, aryl]} and their respective cobalt complexes {Co[2,6-bis(RSCH2)pyridine]Cl2 and Co[bis(RSCH2CH2)amine]Cl2} were synthesized and characterized. Crystal structures of Co[2,6-bis(RSCH2)pyridine]Cl2 [R = -CH3 (), -CH2CH3 (), -CH2CH2CH2CH3 () and -C6H5 ()] are reported in which crystallized as a homo-bimetallic dimer that incorporated two bridging chloride atoms in an octahedral geometry around each cobalt center, while , and crystallized as mono-metallic species characterized by trigonal bipyramidal arrangement of ligands around each cobalt center. As catalysts for the homogeneous selective oxidation of n-octane, the catalysts yielded ketones as the dominant products with a selectivity of ca. 90% for the most active catalyst Co[bis(CH2CH2SCH2CH2)amine]Cl2 () at a total n-octane conversion of 23%. Using tert-butyl hydroperoxide (TBHP) as an oxidant, optimization of reaction conditions is also reported.

  4. Binuclear copper(II) complexes with N4O3 coordinating heptadentate ligand: synthesis, structure, magnetic properties, density-functional theory study, and catecholase activity.

    Science.gov (United States)

    Banerjee, Atanu; Sarkar, Sumana; Chopra, Deepak; Colacio, Enrique; Rajak, Kajal Krishna

    2008-05-19

    The N4O3 coordinating heptadentate ligand afforded binuclear complex [Cu 2(H 2L)(mu-OH)](ClO4)2 (1) and [Cu2(L)(H2O)2]PF6 (2). In complex 1, two copper ions are held together by mu-phenoxo and mu-hydroxo bridges, whereas in complex 2, the copper centers are connected only by a mu-phenoxo bridge. In 1, both the Cu(II) centers have square pyramidal geometry (tau=0.01-0.205), whereas in the case of 2, one Cu(II) center has square pyramidal (tau=0.2517) and other one has square based pyramidal distorted trigonal bipyramidal (tau=0.54) geometry. Complexes 1 and 2 show an strong intramolecular and very weak antiferromagnetic interaction, respectively. Density-functional theory calculations were performed to establish the magneto structural correlation between the two paramagnetic copper(II) centers. Both of the complexes display a couple of one-electron reductive responses near -0.80 and -1.10 V. The complexes show significant catalytic activity at pH 8.5 on the oxidation of 3,5-di- tert-butylcatechol (3,5-DTBC) to 3,5-di- tert-butylquinone (3,5-DTBQ), and the activity measured in terms of kcat=29-37 h(-1).

  5. Substrate binding and catalytic mechanism in phospholipase C from Bacillus cereus. a molecular mechanics and molecular dynamics study

    DEFF Research Database (Denmark)

    da Graça Thrige, D; Buur, J R; Jørgensen, Flemming Steen

    1997-01-01

    For the first time a consistent catalytic mechanism of phospholipase C from Bacillus cereus is reported based on molecular mechanics calculations. We have identified the position of the nucleophilic water molecule, which is directly involved in the hydrolysis of the natural substrate phosphatidyl......For the first time a consistent catalytic mechanism of phospholipase C from Bacillus cereus is reported based on molecular mechanics calculations. We have identified the position of the nucleophilic water molecule, which is directly involved in the hydrolysis of the natural substrate...... phosphatidylcholine, in phospholipase C. This catalytically essential water molecule, after being activated by an acidic residue (Asp55), performs the nucleophilic attack on the phosphorus atom in the substrate, leading to a trigonal bipyramidal pentacoordinated intermediate (and structurally similar transition state......). The subsequent collapse of the intermediate, regeneration of the enzyme, and release of the products has to involve a not yet identified second water molecule. The catalytic mechanism reported here is based on a series of molecular mechanics calculations. First, the x-ray structure of phospholipase C from B...

  6. Polyoxometal cations within polyoxometalate anions. Seven-coordinate uranium and zirconium heteroatom groups in [(UO2)12(μ3-O)4(μ2-H2O)12(P2W15O56)4]32- and [Zr4(μ3-O)2(μ2-OH)2(H2O)4 (P2W16O59)2]14-

    Science.gov (United States)

    Gaunt, Andrew J.; May, Iain; Collison, David; Travis Holman, K.; Pope, Michael T.

    2003-08-01

    Two new composite polyoxotungstate anions with unprecedented structural features, [(UO2)12(μ3-O)4(μ2-H2O)12(P2W15O56)4]32- (1) and [Zr4(μ3-O)2(μ2-OH)2(H2O)4 (P2W16O59)2]14- (2) contain polyoxo-uranium and -zirconium clusters as bridging units. The anions are synthesized by reaction of Na12[P2W15O56] with solutions of UO2(NO3)2 and ZrCl4. The structure of 1 in the sodium salt contains four [P2W15O56]12- anions assembled into an overall tetrahedral cluster by means of trigonal bridging groups formed by three equatorial-edge-shared UO7 pentagonal bipyramids. The structure of anion 2 consists of a centrosymmetric assembly of two [P2W16O59]12- anions linked by a {Zr4O2(OH)2(H2O)4}10+ cluster. Both complexes in solution yield the expected two-line 31P-NMR spectra with chemical shifts of -2.95, -13.58 and -6.45, -13.69 ppm, respectively.

  7. X-ray crystallographic characterization of the Co(II)-substituted Tris-bound form of the aminopeptidase from Aeromonas proteolytica.

    Science.gov (United States)

    Munih, Petra; Moulin, Aaron; Stamper, Carin C; Bennett, Brian; Ringe, Dagmar; Petsko, Gregory A; Holz, Richard C

    2007-08-01

    The X-ray crystal structure of the Co(II)-loaded form of the aminopeptidase from Aeromonas proteolytica ([CoCo(AAP)]) was solved to 2.2A resolution. [CoCo(AAP)] folds into an alpha/beta globular domain with a twisted beta-sheet hydrophobic core sandwiched between alpha-helices, identical to [ZnZn(AAP)]. Co(II) binding to AAP does not introduce any major conformational changes to the overall protein structure and the amino acid residues ligated to the dicobalt(II) cluster in [CoCo(AAP)] are the same as those in the native Zn(II)-loaded structure with only minor perturbations in bond lengths. The Co(II)-Co(II) distance is 3.3A. Tris(hydroxymethyl)aminomethane (Tris) coordinates to the dinuclear Co(II) active site of AAP with one of the Tris hydroxyl oxygen atoms (O4) forming a single oxygen atom bridge between the two Co(II) ions. This is the only Tris atom coordinated to the metals with Co1-O and Co2-O bonds distances of 2.2 and 1.9A, respectively. Each of the Co(II) ions resides in a distorted trigonal bipyramidal geometry. This important structure bridges the gap between previous structural and spectroscopic studies performed on AAP and is discussed in this context.

  8. Bis(μ-4-methylbenzoato-κ2O:O′bis[aqua(4-methylbenzoato-κ2O,O′zinc(II]–bis(μ-4-methylbenzoato-κ2O:O′bis[(4-methylbenzoato-κO(nicotinamide-κNzinc(II]–water (1/1/2

    Directory of Open Access Journals (Sweden)

    Tuncer Hökelek

    2010-07-01

    Full Text Available The crystal structure of the title compound, [Zn2(C8H7O24(H2O2]·[Zn2(C8H7O24(C6H6N2O2]·2H2O, consists of two kinds of dinuclear ZnII complexes (complex A and complex B and uncoordinated water molecules. In complex A, [Zn2(C8H7O24(H2O2], each Zn cation is chelated by a 4-methylbenzoate (PMB anion and coordinated by a water molecule, and is further bridged by two PMB anions in a trigonal-bipyramidal geometry. In complex B, [Zn2(C8H7O24(C6H6N2O2], each ZnII cation is coordinated by a monodentate PMB anion and one nicotinamide (NA ligand, and is further bridged by two PMB anions in a tetrahedral geometry. Weak intra-molecular π–π stacking between adjacent benzene rings is observed in complex B, the centroid–centroid distance being 3.710 (2 Å. Extensive O—H...O and N—H...O hydrogen bonding and weak C—H...O hydrogen bonding is present in the crystal structure. The crystal studied was a racemic twin; the minor twin component refined to 38%.

  9. Synthesis and spectral studies of organotin(IV) 4-amino-3-alkyl-1,2,4-triazole-5-thionates: In vitro antimicrobial activity

    Science.gov (United States)

    Nath, Mala; Sulaxna; Song, Xueqing; Eng, George; Kumar, Ashok

    2008-09-01

    Some di- and triorganotin(IV) triazolates of general formula, R (4- n) SnL n (where n = 2; R = Me, n-Bu and Ph; n = 1; R = Me, n-Pr, n-Bu and Ph and HL = 4-amino-3-methyl-1,2,4-triazole-5-thiol (HL- 1); and 4-amino-3-ethyl-1,2,4-triazole-5-thiol (HL- 2)) were synthesized by the reaction of R (4- n) SnCl n with sodium salt of HL- 1 and HL- 2. The bonding and coordination behavior in these derivatives have been discussed on the basis of IR and 119Sn Mössbauer spectroscopic studies in the solid state. Their coordination behavior in solution is discussed by multinuclear ( 1H, 13C and 119Sn) NMR spectral studies. The IR and 119Sn Mössbauer spectroscopic studies indicate that the ligands, HL- 1 and HL- 2 act as a monoanionic bidentate ligand, coordinating through Sexo- and Nring. The distorted skew trapezoidal-bipyramidal and distorted trigonal bipyramidal geometries have been proposed for R 2SnL 2 and R 3SnL, respectively, in the solid state. In vitro antimicrobial screening of some of the newly synthesized derivatives and of some di- and triorganotin(IV) derivatives of 3-amino-1,2,4-triazole-5-thiol (HL- 3) and 5-amino-3H-1,3,4-thiadiazole-2-thiol (HL- 4) along with two standard drugs such as fluconazole and ciprofloxacin have been carried out against the bacteria, viz. Staphylococcus aureus and Escherichia coli, and against some fungi, viz. Aspergillus fumigatus, Candida albicans, Candida albicans (ATCC 10231), Candida krusei (GO 3) and Candida glabrata (HO 5) by the filter paper disc method. The studied organotin(IV) compounds show mild antifungal activity as compared to that of fluconazole, however, they show almost insignificant activity against the studied Gram-positive ( Staphylococcus aureas) and Gram-negative ( Escherichia coli) bacteria as compared to that of standard drug, ciprofloxacin.

  10. Deviations from the Most Spherical Deltahedra in Rhenatricarbaboranes Having 2n + 2 Wadean Skeletal Electrons.

    Science.gov (United States)

    Attia, Amr A A; Lupan, Alexandru; King, R Bruce

    2017-12-18

    Density functional theory studies on the rhenatricarbaboranes C 3 B n-4 H n-1 Re(CO) 3 (n = 7-12) show that the lowest energy polyhedra for n-vertex metallaboranes having 2n + 2 skeletal electrons and sufficiently dissimilar vertex atoms can deviate from the most spherical closo deltahedra predicted by application of the Wade-Mingos rules. Furthermore, the lowest energy structures of these rhenatricarbaboranes are found to avoid C-C edges and have carbon atoms located at degree 4 rather than degree 5 vertices. The lowest energy structures for the 7-vertex C 3 B 3 H 6 Re(CO) 3 system all have a central C 3 B 3 Re closo deltahedron, namely the pentagonal bipyramid with the rhenium atom at a degree 5 axial vertex and all three carbon atoms at degree 4 equatorial vertices. However, the lowest energy structure for the 8-vertex C 3 B 4 H 7 Re(CO) 3 is not the most spherical closo 8-vertex deltahedron, namely the bisdisphenoid, but instead a central C 3 B 4 Re hexagonal bipyramid with mutually nonadjacent degree 4 vertices for the carbon atoms. Similarly, the lowest energy 10-vertex C 3 B 6 H 9 Re(CO) 3 structures are derived from isocloso deltahedra having three degree 4 vertices for all three carbon atoms rather than from the most spherical 10-vertex closo deltahedron, namely the bicapped square antiprism with only two degree 4 vertices. However, for the 9-vertex C 3 B 5 H 8 Re(CO) 3 system, the most spherical closo deltahedron, namely the tricapped trigonal prism, has three mutually nonadjacent degree 4 vertices, which is ideal for the three carbon atoms and thus is the preferred deltahedron. The preferred deltahedron for the 11-vertex C 3 B 7 H 10 Re(CO) 3 remains the most spherical closo deltahedron despite having only two degree 4 vertices for the carbon atoms. Furthermore, the six lowest energy 12-vertex C 3 B 8 H 11 Re(CO) 3 structures are all based on the regular icosahedron generally favored in polyhedral borane chemistry despite its complete lack of degree 4

  11. Local structure of dilute aqueous DMSO solutions, as seen from molecular dynamics simulations

    Science.gov (United States)

    Idrissi, Abdenacer; Marekha, Bogdan A.; Barj, Mohammed; Miannay, François Alexandre; Takamuku, Toshiyuki; Raptis, Vasilios; Samios, Jannis; Jedlovszky, Pál

    2017-06-01

    The information about the structure of dimethyl sulfoxide (DMSO)-water mixtures at relatively low DMSO mole fractions is an important step in order to understand their cryoprotective properties as well as the solvation process of proteins and amino acids. Classical MD simulations, using the potential model combination that best reproduces the free energy of mixing of these compounds, are used to analyze the local structure of DMSO-water mixtures at DMSO mole fractions below 0.2. Significant changes in the local structure of DMSO are observed around the DMSO mole fraction of 0.1. The array of evidence, based on the cluster and the metric and topological parameters of the Voronoi polyhedra distributions, indicates that these changes are associated with the simultaneous increase of the number of DMSO-water and decrease of water-water hydrogen bonds with increasing DMSO concentration. The inversion between the dominance of these two types of H-bonds occurs around XDMSO = 0.1, above which the DMSO-DMSO interactions also start playing an important role. In other words, below the DMSO mole fraction of 0.1, DMSO molecules are mainly solvated by water molecules, while above it, their solvation shell consists of a mixture of water and DMSO. The trigonal, tetrahedral, and trigonal bipyramidal distributions of water shift to lower corresponding order parameter values indicating the loosening of these orientations. Adding DMSO does not affect the hydrogen bonding between a reference water molecule and its first neighbor hydrogen bonded water molecules, while it increases the bent hydrogen bond geometry involving the second ones. The close-packed local structure of the third, fourth, and fifth water neighbors also is reinforced. In accordance with previous theoretical and experimental data, the hydrogen bonding between water and the first, the second, and the third DMSO neighbors is stronger than that with its corresponding water neighbors. At a given DMSO mole fraction, the

  12. Rhenium(V) and technetium(V) nitrido complexes with mixed tridentate π-donor and monodentate π-acceptor ligands.

    Science.gov (United States)

    Boschi, Alessandra; Cazzola, Emiliano; Uccelli, Licia; Pasquali, Micol; Ferretti, Valeria; Bertolasi, Valerio; Duatti, Adriano

    2012-03-05

    Mixed-ligand [M(N)(SNS)(PPh(3))] complexes (M = Tc, Re) (1, 2) were prepared by reaction of the precursor [M(N)Cl(2)(PPh(3))(2)] with ligand 2,2'-dimercaptodiethylamine [H(2)SNS = NH(CH(2)CH(2)SH)(2)] in refluxing dichloromethane/ethanol mixtures. In these compounds, 2,2'-dimercaptodiethylamine acts as a dianionic tridentate chelating ligand bound to the [M≡N](2+) group through the two π-donor deprotonated sulfur atoms and the protonated amine nitrogen atom. Triphenylphosphine completes the coordination sphere, acting as a monodentate ligand. [M(N)(NS(2))(PPh(3))] complexes can assume two different isomeric forms depending on the syn and anti orientations of the hydrogen atom bound to the central nitrogen atom of the SNS ligand with respect to the M≡N moiety. X-ray crystallography of the syn isomer of complex 2 demonstrated that it has a distorted trigonal bipyramidal geometry with the nitrido group and the two sulfur atoms defining the equatorial plane, the phosphorus atom of the monophosphine and the protonated amine nitrogen of the tridentate ligand spanning the two reciprocal trans positions along the axis perpendicular to the trigonal plane. Synthesis of the analogous Tc derivatives with tris(2-cyanoethyl)phosphine, [Tc(N)(SNS)(PCN)] [(PCN = P(CH(2)CH(2)CN)(3)], required the preliminary preparation of the new precursor [Tc(N)(PCN)(2)Cl(2)](2) (3), which was prepared by reacting [n-NBu(4)][Tc(N)Cl(4)] with a high excess of PCN. The crystal structure of compound 3 consists of a noncrystallographic centrosymmetric dimer of Tc(V) nitrido complexes having an octahedral geometry. In this arrangement, the apical positions are occupied by two tris(2-cyanoethyl)phosphine groups and the equatorial positions by the nitrido group whereas the two Cl(-) anions and one cyano ligand belong to the other octahedral component of the dimer. By reacting the new precursor [Tc(N)(PCN)(2)Cl(2)](2) with the ligand H(2)SNS the complex [Tc(N)(SNS)(PCN)] (5) was finally obtained in

  13. X-ray analyses, spectroscopic and magnetic properties of [Cu 4(succinato)(tpmc) 2](ClO 4) 6·2C 2H 5OH·4H 2O and [Cu 2(C 6H 5COO)tpmc](ClO 4) 3·0.5CH 3OH·0.5H 2O complexes

    Science.gov (United States)

    Vučković, G.; Antonijević-Nikolić, M.; Lis, T.; Mroziński, J.; Korabik, M.; Radanović, D. D.

    2008-01-01

    [Cu 4(succinato)(tpmc) 2](ClO 4) 6 · 2H 2O (tpmc = N, N', N″, N‴-tetrakis-(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane, succinato = dianion of succinic acid) has been prepared and characterized by elemental analysis, UV/vis, IR, EPR (X-band) spectra, conductivity and magnetization measurements (SQUID). Based on a low-temperature measurements (100(2) K), X-ray analyses of the first tetranuclear Cu(II)-tpmc complex, single crystal of which corresponded to the [Cu 4(succinato)(tpmc) 2](ClO 4) 6·2C 2H 5OH·4H 2O ( 1) and of the previously described [Cu 2(C 6H 5COO)tpmc](ClO 4) 3·0.5CH 3OH·0.5H 2O ( 2) were also done. The complexes crystallize in triclinic P1¯ ( 1) and monoclinic P2 1/ c ( 2) space groups. The geometry around the first Cu(II) coordination sphere in the tetranuclear complex ( 1) is almost regular square-based pyramidal, while significant distortion around the other metallic center was observed. The angular structural parameter ( τ), which is applicable to five coordinate structures as an index of degree of trigonality, was found to be 0.05 and 0.40, respectively. In the binuclear complex ( 2) the geometry around the first Cu(II) coordination sphere is regular square-based pyramidal ( τ = 0.09), while around the other is distorted trigonal bipyramidal ( τ = 0.79). In complexes ( 1) and ( 2) the bridging carboxylate groups are coordinated to metallic centres in a syn- anti mode. Weak ferromagnetic interactions are observed between copper(II) ions, connected through syn- anti monocarboxylate bridges (2 J = +1.26 and +1.84 cm -1 in complexes ( 1) and ( 2), respectively). Additional antiferromagnetic interaction through succinato anion ( zJ' = -1.57 cm -1) gives finally rise to antiferromagnetic interactions, observed in magnetic measurements in tetrameric complex ( 1).

  14. Solution [Cu(amm)]2+ is a strongly solvated square pyramid: a full account of the copper K-edge XAS spectrum within single-electron theory.

    Science.gov (United States)

    Frank, Patrick; Benfatto, Maurizio; Hedman, Britt; Hodgson, Keith O

    2008-05-19

    The solution structure of Cu(II) in 4 M aqueous ammonia, [Cu(amm)](2+), was assessed using copper K-edge extended X-ray absorption fine structure (EXAFS) and Minuit XANes (MXAN) analyses. Tested structures included trigonal planar, planar and D2d -tetragonal, regular and distorted square pyramids, trigonal bipyramids, and Jahn-Teller distorted octahedra. Each approach converged to the same axially elongated square pyramid, 4 x Cu-Neq=2.00+/-0.02 A and 1 x Cu-Nax=2.16+/-0.02 A (EXAFS) or 2.20+/-0.07 A (MXAN), with strongly localized solvation shells. In the MXAN model, four equatorial ammonias averaged 13 degrees below the Cu(II) xy-plane, which was 0.45+/-0.1 A above the mean N4 plane. When the axial ligand equilibrium partial occupancies of about 0.65 ammonia and 0.35 water were included, EXAFS modeling found Cu-Lax distances of 2.16 and 2.31 A, respectively, reproducing the distances found in the crystal structures of [Cu(NH3)5](2+) and [Cu(NH3)4(H2O)](2+). A transverse axially localized solvent molecule was found at 2.8 A (EXAFS) or 3.1 A (MXAN). Six second-shell solvent molecules were also found at about 3.4+/-0.01 (EXAFS) or 3.8+/-0.2 A (MXAN). The structure of Cu(II) in 4 M pH 10 aqueous NH 3 may be notationally described as {[Cu(NH 3)4.62(H2O)0.38](solv)}(2+).6solv, solv=H2O, NH 3. The prominent shoulder and duplexed maximum of the rising K-edge XAS of [Cu(amm)](2+) primarily reflect the durable and well-organized solvation shells, not found around [Cu(H2O)5](2+), rather than two-electron shakedown transitions. Not accounting for solvent scattering thus may confound XAS-based estimates of metal-ligand covalency. [Cu(amm)](2+) continues the dissymmetry previously found for the solution structure of [Cu(H2O)5](2+), again contradicting the rack-bonding theory of blue copper proteins.

  15. Lanthanide Organophosphate Spiro Polymers: Synthesis, Structure, and Magnetocaloric Effect in the Gadolinium Polymer.

    Science.gov (United States)

    Gupta, Sandeep K; Bhat, Gulzar A; Murugavel, Ramaswamy

    2017-08-07

    Spirocyclic lanthanide organophosphate polymers, {[Ln(dipp)(dippH)(CH3OH)(H2O)2](CH3OH)2}n [Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11)], have been prepared from the reaction of Ln(NO3)3·xH2O with sterically hindered 2,6-diisopropylphenyl phosphate (dippH2) using aqueous NaOH as the base. The one-dimensional chainlike lanthanide (III) organophosphate coordination polymers have been characterized with the aid of analytical and spectroscopic methods. The single crystal structure determination of polymers (2-5 and 7-11) reveals that in these compounds the hydrophobic organic groups of the phosphate provide a protective coating for the inorganic lanthanide phosphate polymeric chain. The encapsulation of inorganic lanthanide phosphate core, which has very low solubility product, within the organic groups assists in the facile crystallization of the polymers. The di- and monoanionic organophosphate ligands dipp(2-) and dippH(-) display [2.111] and [2.110] binding modes, respectively, in 2-5 and 7. However, they exhibit only [2.110] binding mode in the case of 8-11. This results in the formation of two different types of polymers. While the lighter rare-earth metal ions in 2-5 and 7 display eight coordinate biaugmented trigonal prismatic geometry, the heavier rare-earth metal ions in 9-11 exhibit a seven coordinate capped trigonal prismatic environment. The Tb(III) ion in 8 displays distorted pentagonal bipyramidal geometry. Magnetic studies reveal the presence of weak antiferromagnetic interactions between the Ln(III) ions through the organophosphate ligand. The isotropic Gd(III) polymer 7 exhibits a maximum entropy change of 17.83 J kg(-1) K(-1) for a field change of 7.0 T at 2.5 K, which is significant considering the high molecular weight of the organophosphate ligand. These polymers represent the first family of any structurally characterized rare-earth organophosphate polymers derived from monoesters of phosphoric

  16. Oxygen-storage behavior and local structure in Ti-substituted YMnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Levin, I., E-mail: igor.levin@nist.gov [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Krayzman, V.; Vanderah, T.A. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Tomczyk, M. [Department of Ceramics and Glass Engineering, University of Aveiro, Aveiro 3810-193 (Portugal); Wu, H. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Tucker, M.G. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Playford, H.Y. [ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxford (United Kingdom); Woicik, J.C.; Dennis, C.L. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Vilarinho, P.M. [Department of Ceramics and Glass Engineering, University of Aveiro, Aveiro 3810-193 (Portugal)

    2017-02-15

    Hexagonal manganates RMnO{sub 3} (R=Y, Ho, Dy) have been recently shown to exhibit oxygen-storage capacities promising for three-way catalysts, air-separation, and related technologies. Here, we demonstrate that Ti substitution for Mn can be used to chemically tune the oxygen-breathing properties of these materials towards practical applications. Specifically, Y(Mn{sub 1−x}Ti{sub x})O{sub 3} solid solutions exhibit facile oxygen absorption/desorption via reversible Ti{sup 3+}↔Ti{sup 4+} and Mn{sup 3+}↔Mn{sup 4+} reactions already in ambient air at ≈400 °C and ≈250 °C, respectively. On cooling, the oxidation of both cations is accompanied by oxygen uptake yielding a formula YMn{sup 3+}{sub 1−x-y}Mn{sup 4+}{sub y}Ti{sup 4+}{sub x}O{sub 3+δ}. The presence of Ti promotes the oxidation of Mn{sup 3+} to Mn{sup 4+}, which is almost negligible for YMnO{sub 3} in air, thereby increasing the uptake of oxygen beyond that required for a given Ti{sup 4+} concentration. The reversibility of the redox reactions is limited by sluggish kinetics; however, the oxidation process continues, if slowly, even at room temperature. The extra oxygen atoms are accommodated by the large interstices within a triangular lattice formed by the [MnO{sub 5}] trigonal bipyramids. According to bond distances from Rietveld refinements using the neutron diffraction data, the YMnO{sub 3} structure features under-bonded Mn and even more severely under-bonded oxygen atoms that form the trigonal bases of the [MnO{sub 5}] bipyramids. The tensile bond strain around the 5-fold coordinated Mn site and the strong preference of Ti{sup 4+}(and Mn{sup 4+}) for higher coordination numbers likely provide driving forces for the oxidation reaction. Reverse Monte Carlo refinements of the local atomic displacements using neutron total scattering revealed how the excess oxygen atoms are accommodated in the structure by correlated local displacements of the host atoms. Large displacements of the under

  17. Synthesis, photophysical properties and structures of organotin-Schiff bases utilizing aromatic amino acid from the chiral pool and evaluation of the biological perspective of a triphenyltin compound.

    Science.gov (United States)

    Basu Baul, Tushar S; Kehie, Pelesakuo; Duthie, Andrew; Guchhait, Nikhil; Raviprakash, Nune; Mokhamatam, Raveendra B; Manna, Sunil K; Armata, Nerina; Scopelliti, Michelangelo; Wang, Ruimin; Englert, Ulli

    2017-03-01

    Five new organotin(IV) complexes of compositions [Me2SnL1] (1), [Me2SnL2]n (2), [Me2SnL3] (3), [Ph3SnL1H]n (4) and [Ph3SnL3H] (5) (where L1=(2S)-2-((E)-((Z)-4-hydroxypent-3-en-2-ylidene)amino)-3-(1H-indol-3-yl)propanoate, L2=(2S)-(E)-2-((2-hydroxybenzylidene)amino)-3-(1H-indol-3-yl)propanoate and L3=(2S)-(E)-2-((1-(2-hydroxyphenyl)ethylidene)amino)-3-(1H-indol-3-yl)propanoate were synthesized and spectroscopically characterized. The crystal structures of 1-4 were determined. For the dimethyltin derivative 2, a polymeric chain structure was observed as a result of a long Sn∙∙∙O contact involving the exocyclic carbonyl oxygen-atom from the tridentate ligand of a neighboring Sn-complex unit. The tin atom in this complex has a distorted octahedral coordination geometry, in which the long Sn-O bond is almost trans to the tridentate ligand nitrogen-atom. In contrast, the dimethyltin(IV) complexes 1 and 3 displayed discrete monomeric structures where the tin atom has distorted trigonal-bipyramidal geometry with the two coordinating L oxygen atoms defining the axial positions. On the other hand, 4 is a chain polymer in the solid state. The ligand-bridged Sn atoms adopt a trans-Ph3SnO2 trigonal-bipyramidal configuration with equatorial phenyl groups. A carboxylato oxygen atom from one and the hydroxyl oxygen of the successive ligand in the chain occupy the axial positions. The solution structures were predicted by the use of 119Sn NMR chemical shifts. The photophysical properties of the complexes were investigated in the solid and in solution. The triphenyltin(IV) compound 4 was tested in detail ex vivo against A375 (human melanoma) cell line, exhibiting an IC50 value of 261nM to induce cell death as assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay without significant alteration of cytolysis as determined by lactate dehydrogenase (LDH) assay. Compound 4-mediated potent cell death was also determined by Live and Dead assay and

  18. Four Mixed-Ligand Zn(II Three-Dimensional Metal-Organic Frameworks: Synthesis, Structural Diversity, and Photoluminescent Property

    Directory of Open Access Journals (Sweden)

    Chih-Chieh Wang

    2017-11-01

    Full Text Available Assemblies of four three-dimensional (3D mixed-ligand coordination polymers (CPs having formulas, {[Zn2(bdc2(4-bpdh]·C2H5OH·2H2O}n (1, [Zn(bdc(4-bpdh]n (2, {[Zn2(bdc2(4-bpdh2]·(4-bpdh}n (3, and {[Zn(bdc(4-bpdh]·C2H5OH}n (4 (bdc2− = dianion of 1,4-benzenedicarboxylic acid, 4-bpdh = 2,5-bis(4-pyridyl-3,4-diaza-2,4-hexadiene have been synthesized and structurally characterized by single-crystal X-ray diffraction method. Structural determination reveals that the coordination numbers (geometry of Zn(II ions in 1, 2, 3, and 4 are five (distorted square-pyramidal (SP, six (distorted octahedral (Oh, five (trigonal-bipyramidal (TBP, and four (tetrahedral (Td, respectively, and are bridged by 4-bpdh with bis-monodentate coordination mode and bdc2− ligands with bis-bidentate in 1, chelating/bidentate in 2, bis-monodentate and bis-bidentate in 3, and bis-monodentate in 4, to generate two-fold interpenetrating 3D cube-like metal-organic framework (MOF with pcu topology, non-interpenetrating 3D MOF, two-fold interpenetrating 3D rectangular-box-like MOF with pcu topology and five-fold interpenetrating diamondoid-like MOF with dia topology, respectively. These different intriguing architectures indicate that the coordination numbers and geometries of Zn(II ions, coordination modes of bdc2− ligand, and guest molecules play important roles in the construction of MOFs and the formation of the structural topologies and interpenetrations. Thermal stabilities, and photoluminescence study of 1–4 were also studied in detail. The complexes exhibit ligands based photoluminescence properties at room temperature.

  19. EPR and ligand field studies of iron superoxide dismutases and iron-substituted manganese superoxide dismutases: relationships between electronic structure of the active site and activity.

    Science.gov (United States)

    Renault, J P; Verchère-Béaur, C; Morgenstern-Badarau, I; Yamakura, F; Gerloch, M

    2000-06-12

    The problem of metal selectivity of iron/manganese superoxide dismutases (SODs) is addressed through the electronic structures of active sites using electron paramagnetic resonance and ligand field calculations. Studies of wild-type iron(III) SOD (FeSOD) from Escherichia coli and from Methanobacterium thermoautotrophicum and iron-substituted manganese(III) SOD (Fe(sub)MnSOD) from E. coli and from Serratia marcescens are reported. EPR spectroscopy of wild-type enzymes shows transitions within all three Kramers doublets identified by their g values. From the temperature dependence of the observed transitions, the zero-field splitting is found to be negative, D = -2 +/- 0.2 cm-1. The electronic structure is typical of a distorted trigonal bipyramid, all the EPR features being reproduced by ligand field analysis. This unique and necessary electronic structure characterizes wild-type enzymes whatever their classification from the amino acid sequence into iron or manganese types, as E. coli FeSOD or M. thermoautotrophicum FeSOD. In iron-substituted manganese SODs, reduced catalytic activity is found. We describe how inhomogeneity of all reported substituted MnSODs might explain the activity decrease. EPR spectra of substituted enzymes show several overlapping components. From simulation of these spectra, one component is identified which shares the same electronic structure of the wild-type FeSODs, with the proportion depending on pH. Ligand field calculations were performed to investigate distortions of the active site geometry which induce variation of the excitation energy of the lowest quartet state. The corresponding coupling between the ground state and the excited state is found to be maximum in the geometry of the native SODs. We conjecture that such coupling should be considered in the electron-transfer process and in the contribution of the typical electronic structure of FeSOD to the activity.

  20. Corroborative models of the cobalt(II) inhibited Fe/Mn superoxide dismutases.

    Science.gov (United States)

    Scarpellini, Marciela; Wu, Amy J; Kampf, Jeff W; Pecoraro, Vincent L

    2005-07-11

    Attempting to model superoxide dismutase (SOD) enzymes, we designed two new N3O-donor ligands to provide the same set of donor atoms observed in the active site of these enzymes: K(i)Pr2TCMA (potassium 1,4-diisopropyl-1,4,7-triazacyclononane-N-acetate) and KBPZG (potassium N,N-bis(3,5-dimethylpyrazolylmethyl) glycinate). Five new Co(II) complexes (1-5) were obtained and characterized by X-ray crystallography, mass spectrometry, electrochemistry, magnetochemistry, UV-vis, and electron paramagnetic resonance (EPR) spectroscopies. The crystal structures of 1 and 3-5 revealed five-coordinate complexes, whereas complex 2 is six-coordinate. The EPR data of complexes 3 and 4 agree with those of the Co(II)-substituted SOD, which strongly support the proposition that the active site of the enzyme structurally resembles these models. The redox behavior of complexes 1-5 clearly demonstrates the stabilization of the Co(II) state in the ligand field provided by these ligands. The irreversibility displayed by all of the complexes is probably related to an electron-transfer process followed by a rearrangement of the geometry around the metal center for complexes 1 and 3-5 that probably changes from a trigonal bipyramidal (high spin, d7) to octahedral (low spin, d6) as Co(II) is oxidized to Co(III), which is also expected to be accompanied by a spin-state conversion. As the redox potentials to convert the Co(II) to Co(III) are high, it can be inferred that the redox potential of the Co(II)-substituted SOD may be outside the range required to convert the superoxide radical (O2*-) to hydrogen peroxide, and this is sufficient to explain the inactivity of the enzyme. Finally, the complexes reported here are the first corroborative structural models of the Co(II)-substituted SOD.

  1. Determination of formal redox potentials in aqueous solution of copper(II) complexes with ligands having nitrogen and oxygen donor atoms and comparison with their EPR and UV-Vis spectral features.

    Science.gov (United States)

    Tabbì, Giovanni; Giuffrida, Alessandro; Bonomo, Raffaele P

    2013-11-01

    Formal redox potentials in aqueous solution were determined for copper(II) complexes with ligands having oxygen and nitrogen as donor atoms. All the chosen copper(II) complexes have well-known stereochemistries (pseudo-octahedral, square planar, square-based pyramidal, trigonal bipyramidal or tetrahedral) as witnessed by their reported spectroscopic, EPR and UV-visible (UV-Vis) features, so that a rough correlation between the measured redox potential and the typical geometrical arrangement of the copper(II) complex could be established. Negative values have been obtained for copper(II) complexes in tetragonally elongated pseudo-octahedral geometries, when measured against Ag/AgCl reference electrode. Copper(II) complexes in tetrahedral environments (or flattened tetrahedral geometries) show positive redox potential values. There is a region, always in the field of negative redox potentials which groups the copper(II) complexes exhibiting square-based pyramidal arrangements. Therefore, it is suggested that a measurement of the formal redox potential could be of great help, when some ambiguities might appear in the interpretation of spectroscopic (EPR and UV-Vis) data. Unfortunately, when the comparison is made between copper(II) complexes in square-based pyramidal geometries and those in square planar environments (or a pseudo-octahedral) a little perturbed by an equatorial tetrahedral distortion, their redox potentials could fall in the same intermediate region. In this case spectroscopic data have to be handled with great care in order to have an answer about a copper complex geometrical characteristics. © 2013.

  2. Heteroleptic complexes of Zn(II) based on 1-(5-bromo-2-hydroxybenzylidene)-4-phenylthiosemicarbazide: Synthesis, structural characterization, theoretical studies and antibacterial activity

    Science.gov (United States)

    Azarkish, Mohammad; Akbari, Alireza; Sedaghat, Tahereh; Simpson, Jim

    2017-04-01

    Four new ternary complexes, [ZnL (2,2‧-bipy)] (1), Zn2L2(4,4‧-bipy)] (2), [ZnL(Imd)]·H2O (3) and [ZnL3(MeImd)] (4), have been synthesized from the reaction of Zn(II) acetate with 1-(5-bromo-2-hydroxybenzylidene)-4-phenylthiosemicarbazide (H2L) in the presence of a heterocyclic base, 2,2‧-bipyridine, 4,4‧-bipyridine, imidazole or 2-methylimidazole, as an auxiliary ligand. The complexes have been investigated by elemental analysis and FT-IR, UV-Vis and 1HNMR spectroscopy. These data show that the thiosemicarbazone acts as a tridentate dianionic ligand and coordinates via the thiol group, imine nitrogen, and phenolic oxygen. The coordination sphere was completed by the nitrogen atom(s) of the secondary ligand. The structure of 1 was also confirmed by X-ray crystallography and shown to be a five coordinate complex with coordination geometry between the square-pyramidal and trigonal-bipyramidal. Density functional theory (DFT) calculations including geometry optimization, vibrational frequencies and electronic absorptions have been performed for 1 with the B3LYP functional at the TZP(6-311G*) basis set using the Gaussian 03 or ADF 2009 packages. The optimization calculation showed that the crystallographically determined geometry parameters can be reproduced with that basis set. Experimental IR frequencies and calculated vibration frequencies also support each other. The in vitro antibacterial activities of the ligand and complexes have been evaluated against Gram-positive (B. subtilis and S. aureus) and Gram-negative (P. aeruginosa) bacteria and compared with the standard antibacterial drugs. The results reveal that all of the complexes show much better activity in comparison to the individual thiosemoicarbazone ligand (H2L), against all bacterial strains used, with complex 3 showing the most promising results.

  3. Theoretical study of the electronic states of Nb4, Nb5 clusters and their anions (Nb4?, Nb5?)

    Energy Technology Data Exchange (ETDEWEB)

    Balasubramanian, K; Majumdar, D

    2004-05-06

    Geometries and energy separations of the various low-lying electronic states of Nb{sub n} and Nb{sub n}{sup -} (n = 4, 5) clusters with various structural arrangements have been investigated. The complete active space multi-configuration self-consistent field (CASMCSCF) method followed by multi-reference singles and doubles configuration interaction (MRSDCI) calculations that included up to 52 million configuration spin functions have been used to compute several electronic states of these clusters. The ground states of both Nb{sub 4} ({sup 1}A', pyramidal) and Nb{sub 4}{sup -} ({sup 2}B{sub 3g}, rhombus) are low-spin states at the MRSDCI level. The ground state of Nb{sub 5} cluster is a doublet with a distorted trigonal bipyramid (DTB) structure. The anionic cluster of Nb{sub 5} has two competitive ground states with singlet and triplet multiplicities (DTB). The low-lying electronic states of these clusters have been found to be distorted due to Jahn-Teller effect. On the basis of the energy separations of our computed electronic states of Nb{sub 4} and Nb{sub 5}, we have assigned the observed photoelectron spectrum of Nb{sub n}{sup -}(n = 4, 5) clusters. We have also compared our MRSDCI results with density functional calculations. The electron affinity, ionization potential, dissociation and atomization energies of Nb{sub 4} and Nb{sub 5} have been calculated and the results have been found to be in excellent agreement with the experiment.

  4. Preparation, crystal structure and magnetic properties of di-2-pyridylamine (dpa) copper(II) complexes [Cu(dpa)(N 3) 2] n and [Cu 2(dpa) 2(NCO) 4

    Science.gov (United States)

    Carranza, José; Sletten, Jorunn; Lloret, Francesc; Julve, Miguel

    2008-11-01

    The preparation, crystal structures and magnetic properties of two copper(II) complexes with di-2-pyridylamine (dpa) as end-cap ligand and azide ( 1) and cyanate ( 2) as bridging groups, [Cu(dpa)(N 3) 2] n ( 1) and [Cu 2(dpa) 2(NCO) 4] ( 2), are reported. Compound 1 consists of uniform chains of copper(II) ions bridged by single μ-1,1-azido groups whereas that of compound 2 is made up of centrosymmetric dicopper(II) units with double μ-1,1- N-cyanate bridges, the other two cyanate groups acting as terminal ligands. The copper atoms in 1 and 2 are five-coordinated with two nitrogen atoms of a bidentate dpa ligand ( 1 and 2), one nitrogen atom from a terminally bound azide ( 1)/cyanate ( 2) and two other nitrogens from two azide ( 1)/cyanate ( 2) bridges building intermediate square pyramidal/trigonal bipyramidal ( 1) and distorted square pyramidal ( 2) surroundings. The values of the copper-copper separation through the double end-on azido ( 1) and cyanato ( 2) bridges are 3.8556(4) and 3.5154(5) Å, respectively. Variable-temperature magnetic susceptibility measurements show the occurrence of weak magnetic interactions in both complexes being antiferromagnetic in 1 [ J = -4.60 cm -1, the Hamiltonian is defined as Hˆ=-J∑iS·S] and ferromagnetic in 2 [ J = +3.14 cm -1 with Hˆ=-JS·S]. The magnitude and nature of these magnetic interactions are discussed in the light of the respectives structures and they are compared with those reported for related systems.

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

    Science.gov (United States)

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

    2013-01-18

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

  6. Ternary complexes of copper(II) and cobalt(II) involving nitrite/pyrazole and tetradentate N4-coordinate ligand: Synthesis, characterization, structures and antimicrobial activity

    Science.gov (United States)

    Solanki, Ankita; Sadhu, Mehul H.; Kumar, Sujit Baran

    2015-12-01

    Five new mononuclear mixed ligand complexes of the type [Cu(NCCH3)(dbdmp)](ClO4)2, [M(ONO)(dbdmp)]ClO4, [M(pz) (dbdmp)](ClO4)2 where M = Cu(II) and Co(II), pz = 3,5-dimethylpyrazole and dbdmp = N,N-diethyl-N‧,N‧-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine have been synthesized and characterized by physico-chemical and spectroscopy studies. The crystal structures of three copper(II) complexes [Cu(NCCH3)(dbdmp)](ClO4)2, [Cu(ONO)(dbdmp)]ClO4 and [Cu(pz)(dbdmp)](ClO4)2 have been determined by single crystal X-ray diffraction studies. Structural analyses reveal the geometry of [Cu(pz)(dbdmp)](ClO4)2 is distorted square pyramidal and other two copper(II) complexes have distorted trigonal bipyramidal geometry. Molecular composition of cobalt(II) complexes have been determined by mass spectral data. The EPR spectra of copper(II) complexes in frozen acetonitrile solution exhibit axial spectra, characteristic of dx2-y2 ground state. Electrochemical studies of copper(II) complexes using glassy carbon as working electrode in acetonitrile solution show Cu(II)/Cu(I) couple with quasi reversible electron transfer versus Ag/Ag+ reference electrode. Antimicrobial activity of all the synthesized complexes were investigated against two Gram positive and two Gram negative bacterial strains.

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

    Science.gov (United States)

    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. Metal-ion exchange induced structural transformation as a way of forming novel Ni(II)− and Cu(II)−salicylaldimine structures

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jing-Yun, E-mail: jyunwu@ncnu.edu.tw; Tsai, Chi-Jou; Chang, Ching-Yun; Wu, Yung-Yuan

    2017-02-15

    A Zn(II)−salicylaldimine complex [Zn(L{sup salpyca})(H{sub 2}O)]{sub n} (1, where H{sub 2}L{sup salpyca}=4-hydroxy-3-(((pyridin-2-yl)methylimino)methyl)benzoic acid), with a one-dimensional (1D) chain structure, has been successfully converted to a discrete Ni(II)−salicylaldimine complex [Ni(L{sup salpyca})(H{sub 2}O){sub 3}] (2) and an infinite Cu(II)−salicylaldimine complex ([Cu(L{sup salpyca})]·3H{sub 2}O){sub n} (3) through a metal-ion exchange induced structural transformation process. However, such processes do not worked by Mn(II) and Co(II) ions. Solid-state structure analyses reveal that complexes 1–3 form comparable coordinative or supramolecular zigzag chains running along the crystallographic [201] direction. In addition, replacing Zn(II) ion by Ni(II) and Cu(II) ions caused changes in coordination environment and sphere of metal centers, from a 5-coordinate intermediate geometry of square pyramidal and trigonal bipyramidal in 1 to a 6-coordinate octahedral geometry in 2, and to a 4-coordiante square planar geometry in 3. This study shows that metal-ion exchange serves as a very efficient way of forming new coordination complexes that may not be obtained through direct synthesis. - Graphical abstract: A Zn(II)−salicylaldimine zigzag chain has been successfully converted to a Ni(II)−salicylaldimine supramolecular zigzag chain and a Cu(II)−salicylaldimine coordinative zigzag chain through metal-ion exchange induced structural transformations, which is not achieved by Mn(II) and Co(II) ions.

  9. The multiple conformational charge states of zinc(II) coordination by 2His-2Cys oligopeptide investigated by ion mobility-mass spectrometry, density functional theory and theoretical collision cross sections.

    Science.gov (United States)

    Wagoner, Stephanie M; Deeconda, Manogna; Cumpian, Kayleah L; Ortiz, Rafael; Chinthala, Swetha; Angel, Laurence A

    2016-12-01

    Whether traveling wave ion mobility-mass spectrometry (IM-MS), B3LYP/LanL2DZ density functional theory, and ion size scaled Lennard-Jones (LJ) collision cross sections (CCS) from the B3LYP optimized structures could be used to determine the type of Zn(II) coordination by the oligopeptide acetyl-His1 -Cys2 -Gly3 -Pro4 -Tyr5 -His6 -Cys7 (amb5 ) was investigated. The IM-MS analyses of a pH titration of molar equivalents of Zn(II):amb5 showed that both negatively and positively charged complexes formed and coordination of Zn(II) increased as the His and Cys deprotonated near their pKa values. The B3LYP method was used to generate a series of alternative coordination structures to compare with the experimental results. The method predicted that the single negatively charged complex coordinated Zn(II) in a distorted tetrahedral geometry via the 2His-2Cys substituent groups, whereas, the double negatively charged and positively charged complexes coordinated Zn(II) via His, carbonyl oxygens and the C-terminus. The CCS of the B3LYP complexes were calculated using the LJ method and compared with those measured by IM-MS for the various charge state complexes. The LJ method provided CCS that agreed with five of the alternative distorted tetrahedral and trigonal bipyramidal coordinations for the doubly charged complexes, but provided CCS that were 15 to 31 Å2 larger than those measured by IM-MS for the singly charged complexes. Collision-induced dissociation of the Zn(II) complexes and a further pH titration study of amb5B , which included amidation of the C-terminus, suggested that the 2His-2Cys coordination was more significant than coordinations that included the C-terminus. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Tunable regioselectivity in 1,3-butadiene polymerization by using 2,6-bis(dimethyl-2-oxazolin-2-yl)pyridine incorporated transition metal (Cr, Fe and Co) catalysts

    KAUST Repository

    Gong, Dirong

    2015-05-21

    Tridentate complexes Cr(III)Cl3L, [L = 2,6-bis(dimethyl-2-oxazolin-2-yl) pyridine], Fe(III)Cl3L, Fe(II)Cl2L and Co(II)Cl2L have been prepared and fully characterized. The solid structures of Cr(III)Cl3L, Fe(III)Cl3L and Co(II)Cl2L have been revealed by single crystal X-ray diffraction, and the Cr(III)Cl3L and Fe(III)Cl3L complexes both exhibit a distorted octahedral geometry, while the Co(II)Cl2L complex has a trigonal bipyramidal conformation. Four complexes have been examined in regioselective polymerization of butadiene in combination with MAO in toluene at room temperature. The trans-1,4, cis-1,4 enchainment of resultant polybutadiene are controlled by the metal center. Activated by MAO, complex Cr(III)Cl3L produces high level of trans-1,4 selectivity (trans-1,4 up to 93.3%) with moderate polymer yield, complexes Fe(III)Cl3L and Fe(II)Cl2L both show equal cis-1,4 and trans-1,4 with minor 1,2 selectivity (<10%), and Co(II)Cl2L catalyst displays predominated cis-1,4 selectivity, which can be shifted to 1,2 selectivity by adding PPh3 as an additive. Thus, tuning of the cis-1,4, trans-1,4 and 1,2 selectivity in full range via central metal and additive chosen by these 2,6-bis(dimethyl-2-oxazolin-2-yl) pyridine supported catalysts has been achieved. © 2015 Elsevier B.V. All rights reserved.

  11. Synthesis and spectroscopic characterization of mononuclear/binuclear organotin(IV complexes with 1H-1,2,4-triazole-3-thiol: Comparative studies of their antibacterial/antifungal potencies

    Directory of Open Access Journals (Sweden)

    Parveen Bushra

    2015-01-01

    Full Text Available A series of di and triorganotin(IV complexes of the general formula, R2(ClSnL (R= Me: 1; Bu: 2 and R3SnL (R = Bu: 3; Ph: 4 have been synthesized by refluxing equivalent molar ratios of orgnotin(IV chlorides (R2SnCl2/R3SnCl with the 1H-1,2,4-Triazole-3-thiol (LH in dry methanol. The synthesized complexes (1-4 were further treated with CS2 and R2SnCl2/R3SnCl in 1:1:1 molar ratio to yield the homobimetallic complexes of the types R2(ClSnLCS2Sn(ClR2 (R = Me: 5; Bu: 6 and R3SnLCS2SnR3 (R = Bu: 7; Ph: 8. The ligand and the complexes have been characterized by elemental microanalysis (CHNS, FT-IR and multinuclear NMR (1H&13C, and electron ionization mass spectrometry. IR data demonstrates that the dithiocarbamate donor site of the ligand acts in a bidentate manner and there isa trigonal bipyramidal geometry around Sn(IV in solid state. 1H and 13C NMR data supports the tetrahedralgeometry with thiol donor sites of the ligand while tetra and penta coordinated environments around dithiocarboxylate bound tin(IV in solution state. Mass spectrometric data supported well the structures of the synthesized complexes. The homobimetallic derivatives were found more active than mononuclear organotin(IV compounds and free ligand against various strains of bacteria and fungus.

  12. Atomic-resolution studies of In{sub 2}O{sub 3}-ZnO compounds on aberration-corrected electron microscopes

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wentao

    2009-10-23

    In this work, the characteristic inversion domain microstructures of In{sub 2}O{sub 3}(ZnO){sub m} (m=30) compounds were investigated by TEM methods. At bright-atom contrast condition, atomically resolved HR-TEM images of In{sub 2}O{sub 3}(ZnO){sub 30} were successfully acquired in [1 anti 100] zone axis of ZnO, with projected metal columns of {proportional_to}1.6 A well resolved. From contrast maxima in the TEM images, local lattice distortions at the pyramidal inversion domain boundaries were observed for the first time. Lattice displacements and the strain field in two-dimensions were visualized and measured using the 'DALI' algorithm. Atomically resolved single shot and focal series images of In{sub 2}O{sub 3}(ZnO){sub 30} were achieved in both zone axes of ZnO, [1 anti 100] and [2 anti 1 anti 10], respectively. The electron waves at the exit-plane were successfully reconstructed using the software package 'TrueImage'. Finally, a three dimensional atomic structure model for the pyramidal IDB was proposed, with an In distribution of 10%, 20%, 40%, 20% and 10% of In contents over 5 atom columns along basal planes, respectively. Through a detailed structural study of In{sub 2}O{sub 3}(ZnO){sub m} compounds by using phase-contrast and Z-contrast imaging at atomic resolution, In{sup 3+} atoms are determined with trigonal bi-pyramidal co-ordination and are distributed at the pyramidal IDBs. (orig.)

  13. Redetermination of metarossite, CaV5+2O6·2H2O

    Directory of Open Access Journals (Sweden)

    Anaïs Kobsch

    2016-09-01

    Full Text Available The crystal structure of metarossite, ideally CaV2O6·2H2O [chemical name: calcium divanadium(V hexaoxide dihydrate], was first determined using precession photographs, with fixed isotropic displacement parameters and without locating the positions of the H atoms, leading to a reliability factor R = 0.11 [Kelsey & Barnes (1960. Can. Mineral. 6, 448–466]. This communication reports a structure redetermination of this mineral on the basis of single-crystal X-ray diffraction data of a natural sample from the Blue Cap mine, San Juan County, Utah, USA (R1 = 0.036. Our study not only confirms the structural topology reported in the previous study, but also makes possible the refinement of all non-H atoms with anisotropic displacement parameters and all H atoms located. The metarossite structure is characterized by chains of edge-sharing [CaO8] polyhedra parallel to [100] that are themselves connected by chains of alternating [VO5] trigonal bipyramids parallel to [010]. The two H2O molecules are bonded to Ca. Analysis of the displacement parameters show that the [VO5] chains librate around [010]. In addition, we measured the Raman spectrum of metarossite and compared it with IR and Raman data previously reported. Moreover, heating of metarossite led to a loss of water, which results in a transformation to the brannerite-type structure, CaV2O6, implying a possible dehydration pathway for the compounds M2+V2O6·xH2O, with M = Cu, Cd, Mg or Mn, and x = 2 or 4.

  14. Role of Tricoordinate Al Sites in CH3ReO3/Al2O3 Olefin Metathesis Catalysts.

    Science.gov (United States)

    Valla, Maxence; Wischert, Raphael; Comas-Vives, Aleix; Conley, Matthew P; Verel, René; Copéret, Christophe; Sautet, Philippe

    2016-06-01

    Re2O7 supported on γ-alumina is an alkene metathesis catalyst active at room temperature, compatible with functional groups, but the exact structures of the active sites are unknown. Using CH3ReO3/Al2O3 as a model for Re2O7/Al2O3, we show through a combination of reactivity studies, in situ solid-state NMR, and an extensive series of DFT calculations, that μ-methylene structures (Al-CH2-ReO3-Al) containing a Re═O bound to a tricoordinated Al (AlIII) and CH2 bound to a four-coordinated Al (AlIVb) are the precursors of the most active sites for olefin metathesis. The resting state of CH3ReO3/Al2O3 is a distribution of μ-methylene species formed by the activation of the C-H bond of CH3ReO3 on different surface Al-O sites. In situ reaction with ethylene results in the formation of Re metallacycle intermediates, which were studied in detail through a combination of solid-state NMR experiments, using labeled ethylene, and DFT calculations. In particular, we were able to distinguish between metallacycles in TBP (trigonal-bipyramidal) and SP (square-pyramidal) geometry, the latter being inactive and detrimental to catalytic activity. The SP sites are more likely to be formed on other Al sites (AlIVa/AlIVa). Experimentally, the activity of CH3ReO3/Al2O3 depends on the activation temperature of alumina; catalysts activated at or above 500 °C contain more active sites than those activated at 300 °C. We show that the dependence of catalytic activity on the Al2O3 activation temperature is related to the quantity of available AlIII-defect sites and adsorbed H2O.

  15. Synthesis, thermogravimetric study and crystal structure of an N-rich copper(II) compound with tren ligands and nitrate counter-anions

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-Toro, Inmaculada; Domínguez-Martín, Alicia [Department of Inorganic Chemistry, Faculty of Pharmacy, University of Granada, 18071 Granada (Spain); Choquesillo-Lazarte, Duane [Laboratorio de Estudios Cristalográficos, IACT, CSIC-Universidad de Granada, Av. de las Palmeras 4, E-18100 Armilla, Granada (Spain); Vílchez-Rodríguez, Esther [Department of Inorganic Chemistry, Faculty of Pharmacy, University of Granada, 18071 Granada (Spain); Department of Inorganic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Castiñeiras, Alfonso [Department of Inorganic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Niclós-Gutiérrez, Juan, E-mail: jniclos@ugr.es [Department of Inorganic Chemistry, Faculty of Pharmacy, University of Granada, 18071 Granada (Spain)

    2014-10-10

    The N-rich salt [{Cu(tren)}{sub 3}(μ{sub 3}-tren)]{sub 2}(NO{sub 3}){sub 12}·3H{sub 2}O has been studied by XRD and by coupled TG and FT-IR spectroscopy of the evolved gases. After water loss, thermal decomposition of the nitrate ions and some tren ligands in the salt are overlapped. - Highlights: • A novel N-rich copper(II)-tren complex has been crystallized as a 3-hydrated nitrate salt. • Tren acts both as tripodal tetradentate and as μ{sub 3}-tren bridging ligand. • Copper(II) centers exhibit distorted trigonal bipyramidal coordination. • Coupled thermogravimetry and FT-IR spectra of evolved gases have been used. • Decomposition of nitrate anions and tren ligands occurs in an overlapped step. - Abstract: The compound [{Cu(tren)}{sub 3}(μ3-tren)]{sub 2}(NO{sub 3}){sub 12}·3H{sub 2}O has been synthesized, crystallized and characterized by single crystal X-ray diffraction, thermogravimetry (TG) coupled to FT-IR spectroscopy of the evolved gases, TG–differential scanning calorimetry (DSC) and electronic (diffuse reflectance) and FT-IR spectroscopies. The sample loses the crystallization water between room temperature and 200 °C. The decomposition of the salt begins with an overlapped decomposition of nitrate anions and some tren ligands where CO{sub 2}, H{sub 2}O, CO, NH{sub 3}, N{sub 2}O, NO and NO{sub 2} are evolved (205–235 °C). Then decomposition of additional tren ligands takes place (235–725 °C). Finally a non-pure CuO residue is obtained at 725 °C.

  16. Three-Dimensional Cadmium(II Cyanide Coordination Polymers with Ethoxy-, Butoxy- and Hexyloxy-ethanol

    Directory of Open Access Journals (Sweden)

    Takeshi Kawasaki

    2016-08-01

    Full Text Available The three novel cadmium(II cyanide coordination polymers with alkoxyethanols, [Cd(CN2(C2H5OCH2CH2OH]n (I, [{Cd(CN2(C4H9OCH2CH2OH}3{Cd(CN2}]n (II and [{Cd(CN2(H2O2}{Cd(CN2}3·2(C6H13OCH2CH2OH]n (III, were synthesized and charcterized by structural determination. Three complexes have three-dimensional Cd(CN2 frameworks; I has distorted tridymite-like structure, and, II and III have zeolite-like structures. The cavities of Cd(CN2 frameworks of the complexes are occupied by the alkoxyethanol molecules. In I and II, hydroxyl oxygen atoms of alkoxyethanol molecules coordinate to the Cd(II ions, and the Cd(II ions exhibit slightly distort trigonal-bipyramidal coordination geometry. In II, there is also tetrahedral Cd(II ion which is coordinated by only the four cyanides. The hydroxyl oxygen atoms of alkoxyethanol connects etheric oxygen atoms of the neighboring alkoxyethanol by hydrogen bond in I and II. In III, hexyloxyethanol molecules do not coordinate to the Cd(II ions, and two water molecules coordnate to the octahedral Cd(II ions. The framework in III contains octahedral Cd(II and tetrahedral Cd(II in a 1:3 ratio. The Cd(CN2 framework structures depended on the difference of alkyl chain for alkoxyethanol molecules.

  17. Structural Evolution of Core-Shell Gold Nanoclusters: Aun(-) (n = 42-50).

    Science.gov (United States)

    Pande, Seema; Huang, Wei; Shao, Nan; Wang, Lei-Ming; Khetrapal, Navneet; Mei, Wai-Ning; Jian, Tian; Wang, Lai-Sheng; Zeng, Xiao Cheng

    2016-11-22

    Gold nanoclusters have attracted great attention in the past decade due to their remarkable size-dependent electronic, optical, and catalytic properties. However, the structures of large gold clusters are still not well-known because of the challenges in global structural searches. Here we report a joint photoelectron spectroscopy (PES) and theoretical study of the structural evolution of negatively charged core-shell gold nanoclusters (Aun(-)) for n = 42-50. Photoelectron spectra of size-selected Aun(-) clusters are well resolved with distinct spectral features, suggesting a dominating structural type. The combined PES data and density functional calculations allow us to systematically identify the global minimum or candidates of the global minima of these relatively large gold nanoclusters, which are found to possess low-symmetry structures with gradually increasing core sizes. Remarkably, the four-atom tetrahedral core, observed first in Au33(-), continues to be highly robust and is even present in clusters as large as Au42(-). Starting from Au43(-), a five-atom trigonal bipyramidal core appears and persists until Au47(-). Au48(-) possesses a six-atom core, while Au49(-) and Au50(-) feature seven- and eight-atom cores, respectively. Notably, both Au46(-) and Au47(-) contain a pyramidal Au20 motif, which is stacked with another truncated pyramid by sharing a common 10-atom triangular face. The present study sheds light on our understanding of the structural evolution of the medium-sized gold nanoclusters, the shells and core as well as how the core-shell structures may start to embrace the golden pyramid (bulk-like) fragment.

  18. Oxo iron(IV) as an oxidative active intermediate of p-chlorophenol in the Fenton reaction: a DFT study.

    Science.gov (United States)

    Mignon, Pierre; Pera-Titus, Marc; Chermette, Henry

    2012-03-21

    Debate continues over which active species plays the role of oxidative agent during the Fenton reaction-the HO˙ radical or oxo iron [Fe(IV)O](2+). In this context, the present study investigates the oxidation of p-chlorophenol by [Fe(IV)O(H(2)O)(5)](2+) using DFT calculations, within gas-phase and micro-solvated models, in order to explore the possible role of oxo iron as a reactant. The results show that the chlorine atom substitution of p-chlorophenol by oxo iron is a highly stabilising step (ΔH = -83 kcal mol(-1)) with a free energy barrier of 5.8 kcal mol(-1) in the micro-solvated model. This illustrates the high oxidising power of the [Fe(IV)O(H(2)O)(5)](2+) complex. On the other hand, the breaking of the Fe-O bond, leading to the formation of hydroquinone, is observed to be the rate-determining step of the reaction. The rather large free energy barrier corresponding to this bond cleavage amounts to 10.2 and 9.3 kcal mol(-1) in the gas-phase and micro-solvated models, respectively. Elsewhere, the lifetime of the HO˙ radical has previously been shown to be extremely small. These facts, combined with observations of oxo iron under certain experimental conditions, suggest that oxo iron is a highly plausible oxidative species of the reaction. In addition, a trigonal bipyramidal iron complex, coordinated either by hydroxyl groups and/or by water molecules, has been found in all described mechanisms. This structure appears to be a stable intermediate; and to our knowledge, it has not been characterised by previous studies.

  19. Five-coordinate complexes [FeX(depe)(2)]BPh(4), X = Cl, Br: electronic structure and spin-forbidden reaction with N(2).

    Science.gov (United States)

    Franke, Oliver; Wiesler, Beatrix E; Lehnert, Nicolai; Näther, Christian; Ksenofontov, Vadim; Neuhausen, Jörg; Tuczek, Felix

    2002-07-01

    The bonding of N(2) to the five-coordinate complexes [FeX(depe)(2)](+), X = Cl (1a) and Br (1b), has been investigated with the help of X-ray crystallography, spectroscopy, and quantum-chemical calculations. Complexes 1a and 1b are found to have an XP(4) coordination that is intermediate between square-pyramidal and trigonal-bipyramidal. Mössbauer and optical absorption spectroscopy coupled with angular overlap model (AOM) calculations reveal that 1a and 1b have (3)B(1) ground states deriving from a (xz)(1)(z(2))(1) configuration. The zero-field splitting for this state is found to be 30-35 cm(-1). In contrast, the analogous dinitrogen complexes [FeX(N(2))(depe)(2)](+), X = Cl (2a) and Br (2b), characterized earlier are low-spin (S = 0; Wiesler, B. E.; Lehnert, N.; Tuczek, F.; Neuhausen, J.; Tremel, W. Angew. Chem, Int. Ed. 1998, 37, 815-817). N(2) bonding and release in these systems are thus spin-forbidden. It is shown by density functional theory (DFT) calculations of the chloro complex that the crossing from the singlet state (ground state of 2a) to the triplet state (ground state of 1a) along the Fe-N coordinate occurs at r(C) = 2.4 A. Importantly, this intersystem crossing lowers the enthalpy calculated for N(2) release by 10-18 kcal/mol. The free reaction enthalpy Delta G degrees for this process is calculated to be 4.7 kcal/mol, which explains the thermal instability of N(2) complex 2a with respect to the loss of N(2). The differences in reactivity of analogous trans hydrido systems are discussed.

  20. Synthesis, structure information, DNA/BSA binding affinity and in vitro cytotoxic studies of mixed ligand copper(II) complexes containing a phenylalanine derivative and diimine co-ligands.

    Science.gov (United States)

    Annaraj, B; Balakrishnan, C; Neelakantan, M A

    2016-07-01

    Binary [Cu(PAIC)(H2O)2]·H2O (1) and mixed ligand [Cu(PAIC)(L)]·2H2O complexes, where PAIC=phenylalanine imidazole carboxylic acid, L=diimine coligands [2,2'-bipyridine (bpy) (2) and 1,10-phenanthroline (phen) (3)] have been synthesized and fully characterized by analytical and spectral techniques. The X-ray structure of [Cu(PAIC)(phen)]·2H2O (3) shows a N4O coordination with square pyramidal geometry around the copper (II) atom. The spin Hamiltonian parameters calculated for the complexes account for the distorted square planar structure and rules out the possibility of a trigonal bipyramidal structure. Interaction of the complexes (1-3) with calf thymus DNA (CT DNA) was studied by using different techniques (absorption titration, fluorescence quenching and thermal melting) and the studies suggest that these complexes bind to CT DNA through intercalation. The DNA-binding affinity of the complexes has further been explained by DFT computational results. Binding activity of Bovine serum albumin (BSA) reveals that the complexes can strongly quench the intrinsic fluorescence of BSA through a static quenching mechanism. DNA cleavage experiments using plasmid DNA pUC 19 show that the complexes exhibit efficient chemical nuclease activity even in the absence of any external additives. The cytotoxicity of the complexes against human normal cell line (HBL 100) and human breast cancer cell line (MCF-7) shows that metal complexation of the ligands results in a significant enhancement in the cell death of MCF-7. Finally, docking studies on DNA and protein binding interactions were performed. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. An EXAFS study of the interaction of substrate with the ferric active site of protocatechuate 3,4-dioxygenase

    Energy Technology Data Exchange (ETDEWEB)

    True, A.E.; Orville, A.M.; Pearce, L.L.; Lipscomb, J.D.; Que, L. Jr. (Univ. of Minnesota, Minneapolis (USA))

    1990-12-01

    X-ray crystallographic studies of the intradiol cleaving protocatechuate 3,4-dioxygenase from Pseudomonas aeruginosa have shown that the enzyme has a trigonal bipyramidal ferric active site with two histidines, two tyrosines, and a solvent molecule as ligands. Fe K-edge EXAFS studies of the spectroscopically similar protocatechuate 3,4-dioxygenase from Brevibacterium fuscum are consistent with a pentacoordinate geometry of the iron active site with 3 O/N ligands at 1.90 {angstrom} and 2 O/N ligands at 2.08 {angstrom}. The 2.08-{angstrom} bonds are assigned to the two histidines, while the 1.90-{angstrom} bonds are associated with the two tyrosines and the coordinated solvent. The short Fe-O distance for the solvent suggests that it coordinates as hydroxide rather than water. When the inhibitor terephthalate is bound to the enzyme, the XANES data indicate that the ferric site becomes 6-coordinate and the EXAFS data show a beat pattern which can only be simulated with an additional Fe-O/N interaction at 2.46 {angstrom}. Together, the data suggest that the oxygens of the carboxylate group in terephthalate displace the hydroxide and chelate to the ferric site but in an asymmetric fashion. In contrast, protocatechuate 3,4-dioxygenase remains 5-coordinate upon the addition of the slow substrate homoprotocatechuic acid (HPCA). Previous EPR data have indicated that HPCA forms an iron chelate via the two hydroxyl functions. For the iron site to remain 5-coordinate and the HPCA to be chelated to the iron, the substrate must displace not only the hydroxide but also a ligand from the protein backbone, probably a histidine. The mechanistic implications of the displacement of hydroxide and a protein ligand in the active site are discussed.

  2. Crystal Structure of the LasA Virulence Factor from Pseudomonas aeruginosa: Substrate Specificity and Mechanism of M23 Metallopeptidases

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, James; Murphy, Loretta M.; Conners, Rebecca; Sessions, Richard B.; Gamblin, Steven J. (Wales); (Bristol Med Sci); (NIMR)

    2010-09-21

    Pseudomonas aeruginosa is an opportunist Gram-negative bacterial pathogen responsible for a wide range of infections in immunocompromized individuals and is a leading cause of mortality in cystic fibrosis patients. A number of secreted virulence factors, including various proteolytic enzymes, contribute to the establishment and maintenance of Pseudomonas infection. One such is LasA, an M23 metallopeptidase related to autolytic glycylglycine endopeptidases such as Staphylococcus aureus lysostaphin and LytM, and to DD-endopeptidases involved in entry of bacteriophage to host bacteria. LasA is implicated in a range of processes related to Pseudomonas virulence, including stimulating ectodomain shedding of the cell surface heparan sulphate proteoglycan syndecan-1 and elastin degradation in connective tissue. Here we present crystal structures of active LasA as a complex with tartrate and in the uncomplexed form. While the overall fold resembles that of the other M23 family members, the LasA active site is less constricted and utilizes a different set of metal ligands. The active site of uncomplexed LasA contains a five-coordinate zinc ion with trigonal bipyramidal geometry and two metal-bound water molecules. Using these structures as a starting point, we propose a model for substrate binding by LasA that explains its activity against a wider range of substrates than those used by related lytic enzymes, and offer a catalytic mechanism for M23 metallopeptidases consistent with available structural and mutagenesis data. Our results highlight how LasA is a structurally distinct member of this endopeptidase family, consistent with its activity against a wider range of substrates and with its multiple roles in Pseudomonas virulence.

  3. Synthesis and crystal structure of the dinuclear copper(II) Schiff base complex μ-hydroxido-μ-chlorido-bis{[bis(trans-2-nitrocinnamaldehyde)ethylenediamine]chloridocopper(II)} dichloromethane sesquisolvate.

    Science.gov (United States)

    Barati, Kazem; Clegg, William; Habibi, Mohammad Hossein; Harrington, Ross W; Lalegani, Arash; Montazerozohori, Morteza

    2016-03-01

    Transition metal complexes of Schiff base ligands have been shown to have particular application in catalysis and magnetism. The chemistry of copper complexes is of interest owing to their importance in biological and industrial processes. The reaction of copper(I) chloride with the bidentate Schiff base N,N'-bis(trans-2-nitrocinnamaldehyde)ethylenediamine {Nca2en, systematic name: (1E,1'E,2E,2'E)-N,N'-(ethane-1,2-diyl)bis[3-(2-nitrophenyl)prop-2-en-1-imine]} in a 1:1 molar ratio in dichloromethane without exclusion of air or moisture resulted in the formation of the title complex μ-chlorido-μ-hydroxido-bis(chlorido{(1E,1'E,2E,2'E)-N,N'-(ethane-1,2-diyl)bis[3-(2-nitrophenyl)prop-2-en-1-imine]-κ(2)N,N'}copper(II)) dichloromethane sesquisolvate, [Cu2Cl3(OH)(C20H18N4O4)2]·1.5CH2Cl2. The dinuclear complex has a folded four-membered ring in an unsymmetrical Cu2OCl3 core in which the approximate trigonal bipyramidal coordination displays different angular distortions in the equatorial planes of the two Cu(II) atoms; the chloride bridge is asymmetric, but the hydroxide bridge is symmetric. The chelate rings of the two Nca2en ligands have different conformations, leading to a more marked bowing of one of the ligands compared with the other. This is the first reported dinuclear complex, and the first five-coordinate complex, of the Nca2en Schiff base ligand. Molecules of the dimer are associated in pairs by ring-stacking interactions supported by C-H...Cl interactions with solvent molecules; a further ring-stacking interaction exists between the two Schiff base ligands of each molecule.

  4. Kinetic and theoretical studies on the protonation of [Ni(2-SC6H4N){PhP(CH2CH2PPh2)2}]+: nitrogen versus sulfur as the protonation site.

    Science.gov (United States)

    Petrou, Athinoula L; Koutselos, Andreas D; Wahab, Hilal S; Clegg, William; Harrington, Ross W; Henderson, Richard A

    2011-02-07

    The complexes [Ni(4-Spy)(triphos)]BPh(4) and [Ni(2-Spy)(triphos)]BPh(4) {triphos = PhP(CH(2)CH(2)PPh(2))(2), 4-Spy = 4-pyridinethiolate, 2-Spy = 2-pyridinethiolate} have been prepared and characterized both spectroscopically and using X-ray crystallography. In both complexes the triphos is a tridentate ligand. However, [Ni(4-Spy)(triphos)](+) comprises a 4-coordinate, square-planar nickel with the 4-Spy ligand bound to the nickel through the sulfur while [Ni(2-Spy)(triphos)](+) contains a 5-coordinate, trigonal-bipyramidal nickel with a bidentate 2-Spy ligand bound to the nickel through both sulfur and nitrogen. The kinetics of the reactions of [Ni(4-Spy)(triphos)](+) and [Ni(2-Spy)(triphos)](+) with lutH(+) (lut = 2,6-dimethylpyridine) in MeCN have been studied using stopped-flow spectrophotometry, and the two complexes show very different reactivities. The reaction of [Ni(4-Spy)(triphos)](+) with lutH(+) is complete within the deadtime of the stopped-flow apparatus (2 ms) and corresponds to protonation of the nitrogen. However, upon mixing [Ni(2-Spy)(triphos)](+) and lutH(+) a reaction is observed (on the seconds time scale) to produce an equilibrium mixture. The mechanistic interpretation of the rate law has been aided by the application of MSINDO semiempirical and ADF calculations. The kinetics and calculations are consistent with the reaction between [Ni(2-Spy)(triphos)](+) and lutH(+) involving initial protonation of the sulfur followed by dissociation of the nitrogen and subsequent transfer of the proton from sulfur to nitrogen. The factors affecting the position of protonation and the coupling of the coordination state of the 2-pyridinethiolate ligand to the site of protonation are discussed.

  5. Fondihaldurid 2006

    Index Scriptorium Estoniae

    2005-01-01

    Investeerimisfondide LHV-Seesam Varahaldus, Hansa Investeerimisfondid, SEB Ühispanga Fondid, Trigon Kesk- ja Ida-Euroopa Fond, Trigon Uus Euroopa Väikeettevõtete Fond, Trigon Teise Laine Fond, SEB Ühispanga Võlakirjafond ja LHV Kauplemismandaat juhid tutvustavad fondide tegevust 2005. aastal ja prognoosivad investeerimisvõimalusi oma piirkonnas aastal 2006

  6. Bis(μ-benzoato-κ2O:O′bis(benzoato-κOoctabutyldi-μ3-oxido-tetratin(IV

    Directory of Open Access Journals (Sweden)

    Hans Reuter

    2017-03-01

    Full Text Available The asymmetric unit of the title compound, [{Sn(C4H92(C6H5COO}2O]2, consists of two half molecules, completed by application of inversion symmetry. Both molecules adopt a ladder structure typical for this class of dimeric tetraorganodistannoxane dicarboxylates characterized by a centrosymmetric four-membered (Sn—O2 ring of rhomboidal shape that is extended on both sides by folded six-membered Sn—O—C rings. To a first approximation, both kinds of Sn atoms (Sni and Sno are trigonal–bipyramidally coordinated. The bond angles between the n-butyl groups are widened [135.64 (7–146.20 (7°] in comparison with an ideal trigonal bipyramid. Sn—O bond lengths within the {R2SnO3} coordination sphere depend strongly on the position of the corresponding O atom – axial (ax or equatorial (eq – as well as on the functionality of the carboxylate groups which exhibit μ2 (–COOi and μ1 (–COOo coordination modes, respectively. In summary, the following sequence of distances [mean values] is found: d(Sno—Oμ3eq [2.024 (2 Å] < d(Sni—Oμ3eq [2.044 (2 Å] < d(Sni—Oμ3ax [2.158 (6 Å] < d(Sno—Oμ1-carbax [2.182 (6 Å] < d(Sni—Oμ2-carbax [2.250 (2 Å] ≃ d(Sno—Oμ2-carbax [2.247 (12 Å]. The n-butyl groups adopt an anti–anti conformation with exception of two disordered outer n-butyl groups of the second molecule which exhibit gauche–anti and anti–gauche conformations. Weak intramolecular Sn...O interactions between the different O atoms of the outer carboxyl groups with the inner, as well as outer, Sn atoms give rise to a strongly distorted octahedral coordination at these Sn atoms. Intermolecular interactions between the individual molecules are restricted to van der Waals and O...H—C interactions of which a nearly linear very short C—H...O contact between the H atom of the phenyl group of one of the molecules with the outer non-coordinating C=O group of the other molecule is the most prominent

  7. Chlorido-bis-(1,10-phenanthroline-κ(2) N,N')copper(II) chlorido-(1,10-phen-anthroline-κ(2) N,N')(pyridine-2,6-di-carboxyl-ato-κ(3) O (2),N,O (6))manganate(II) methanol monosolvate.

    Science.gov (United States)

    Buvailo, Halyna I; Rusanova, Julia A; Makhankova, Valeriya G; Kokozay, Vladimir N; Zubatyuk, Roman I

    2014-04-01

    The title complex, [CuCl(C12H8N2)2][Mn(C7H3NO4)Cl(C12H8N2)]·CH3OH, consists of discrete [CuCl(phen)2](+) cations (phen is 1,10-phenanthroline), [MnCl(pydc)(phen)](-) anions (H2pydc is 2,6-pyridine-2,6-di-carb-oxy-lic acid) and one methanol solvent mol-ecule of crystallization per asymmetric unit. It should be noted, that a solvent-masking procedure as implemented in OLEX2 [Dolomanov et al. (2009). J. Appl. Cryst. 42, 339-341 ▶] was used to remove the electronic contribution from one disordered solvent molecule, presumably methanol. Only the atoms used in the refined model are reported in chemical formula and related values. The Cu(II) ion is five-coordinated by two phenanthroline ligands and one chloride ion in a distorted trigonal-bipyramidal geometry. The dihedral angle between the phen ligands is 65.21 (5)°. The Mn(II) ion is six-coordinated by one Cl atom, two N atoms from a phen ligand, as well one N atom and two O atoms from pydc in a distorted octa-hedral coordination geometry, with cis angles ranging from 72.00 (8) to 122.07 (8)° and trans angles ranging from 143.98 (8) to 163.15 (6)°. In the crystal, C-H⋯O, O-H⋯O and C-H⋯Cl hydrogen bonds, cation-anion π-π inter-actions between the phen ring systems with centroid-centroid distances in the range 3.881 (34)-4.123 (36) Å, as well as cation-cation, anion-anion π-π inter-actions between the phen rings with centroid-centroid distances in the range 3.763 (4)-3.99 (5) Å and pydc rings with centroid-centroid distances 3.52 (5) Å link the various components.

  8. Efficient hydrolytic cleavage of plasmid DNA by chloro-cobalt(II) complexes based on sterically hindered pyridyl tripod tetraamine ligands: synthesis, crystal structure and DNA cleavage.

    Science.gov (United States)

    Massoud, Salah S; Perkins, Richard S; Louka, Febee R; Xu, Wu; Le Roux, Anne; Dutercq, Quentin; Fischer, Roland C; Mautner, Franz A; Handa, Makoto; Hiraoka, Yuya; Kreft, Gabriel L; Bortolotto, Tiago; Terenzi, Hernán

    2014-07-14

    Four new cobalt(ii) complexes [Co(6-MeTPA)Cl]ClO4/PF6 (2/2a), [Co(6-Me2TPA)Cl]ClO4/PF6 (3/3a), [Co(BPQA)Cl]ClO4/PF6 (4/4a) and [Co(BQPA)Cl]ClO4/PF6 (5/5a) as well as [Co(TPA)Cl]ClO4 (1) where TPA = tris(2-pyridylmethyl)amine, 6-MeTPA = ((6-methyl-2-pyridyl)methyl)bis(2-pyridylmethyl)amine, 6-Me2TPA = bis(6-methyl-2-pyridyl)methyl)-(2-pyridylmethyl)amine, BPQA = bis(2-pyridylmethyl)-(2-quinolylmethyl)-amine and BQPA = bis(2-quinolylmethyl)-(2-pyridylmethyl)amine were synthesized and structurally characterized. Single crystal X-ray crystallography confirmed the distorted trigonal bipyramidal geometries of complexes 2a-5a. Spectrophotometric titrations and conductivity measurements of the complexes in the CH3CN-H2O mixture showed that the chloro complexes exist in equilibrium with the corresponding hydrolyzed aqua species, [Co(L)(H2O)](2+). The pKa values of the coordinated H2O in aqua complexes vary from 8.4 to 8.7 (37 °C). The interactions of the complexes (1-5) with DNA have been investigated at pH = 7.0 and 9.0 (10 mM Tris-HCl buffer) and 37 °C where very high catalytic cleavage was observed. Under pseudo Michaelis-Menten kinetic conditions, the catalytic rate constants, kcat, decrease in the order 4>2>5>1>3. At pH 7.0 (10 mM Tris-HCl buffer) and 37 °C, the kcat value for complex 4 (6.02 h(-1)), where [Co(BPQA)(H2O)](2+) is the major species, corresponds to 170 million rate enhancement over the non-catalyzed DNA. Electrophoretic experiments conducted in the presence and absence of radical scavengers (DMSO, KI, NaN3) ruled out the oxidative mechanistic pathway of the reaction and suggested that the hydrolytic mechanism is the preferred one. This finding was in agreement with the observed increase in the kcat values at pH 9.0 compared to the corresponding values at pH 7.0 as a result of the increased concentration of the reactive hydroxo species, [Co(L)(OH)](+). The reactivity of the synthesized complexes in catalyzing the DNA cleavage is discussed in relation to

  9. Correlation between ionic radii of metals and thermal decomposition of supramolecular structure of azodye complexes

    Science.gov (United States)

    El-Sonbati, A. Z.; Diab, M. A.; El-Bindary, A. A.; Eldesoky, A. M.; Morgan, Sh. M.

    2015-01-01

    An interesting azodye heterocyclic ligand of copper(II), cobalt(II), nickel(II) and uranyl(II) complexes have been synthesized by the reaction of metal salts with 5-(2,3-dimethyl-1-phenylpyrazol-5-one azo)-2-thioxo-4-thiazolidinone (HL) yields 1:1 and 1:2 (M:L) complexes depending on the reaction conditions. The elemental analysis, magnetic moments, spectral (UV-Vis, IR, 1H and 13C NMR and ESR) and thermal studies were used to characterize the isolated complexes. The molecular structures of the ligand tautomers are optimized theoretically and the quantum chemical parameters are calculated. The IR spectra showed that the ligand (HL) act as monobasic tridentate/neutral bidentate through the (sbnd Ndbnd N), enolic (Csbnd O)- and/or oxygen keto moiety groups forming a five/six-membered structures. According to intramolecular hydrogen bond leads to increasing of the complexes stability. The molar conductivities show that all the complexes are non-electrolytes. The ESR spectra indicate that the free electron is in dxy orbital. The calculated bonding parameter indicates that in-plane σ-bonding is more covalent than in-plane π-bonding. The coordination geometry is five/six-coordinated trigonal bipyramidal for complex (1) and octahedral for complexes (2-6). The value of covalency factor β12 and orbital reduction factor K accounts for the covalent nature of the complexes. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. The synthesized ligand (HL) and its Cu(II) complexes (1, 2 and 4) are screened for their biological activity against bacterial and fungal species. The ligand (HL) showed antimicrobial activities against Escherichia coli. The ligand (HL) and its Cu(II) complexes (2 and 4) have very high antifungal activity against Penicillium italicum. The inhibitive action of ligand (HL), against the corrosion of C-steel in 2 M HCl solution has been investigated using potentiodynamic polarization and electrochemical

  10. Synthesis, antimicrobial activity and chemotherapeutic potential of inorganic derivatives of 2-(4'-thiazolyl)benzimidazole[thiabendazole]: X-ray crystal structures of [Cu(TBZH)2Cl]Cl.H2O.EtOH and TBZH2NO3 (TBZH=thiabendazole).

    Science.gov (United States)

    Devereux, Michael; McCann, Malachy; Shea, Denis O; Kelly, Rachel; Egan, Denise; Deegan, Carol; Kavanagh, Kevin; McKee, Vickie; Finn, Gregory

    2004-06-01

    Thiabendazole (TBZH) reacts with iron(III) nitrate causing protonation of the ligand to yield the nitrate salt [TBZH(2)NO(3)] (1). Reaction of TBZH with copper(II) acetate results in the deprotonation of the ligand yielding [Cu(TBZ)2.(H2O)2] (2). Reactions of TBZH with the chloride, nitrate and butanedioate salts of copper(II) yields [Cu(TBZH)2Cl]Cl.H2O.EtOH (3), [Cu(TBZH)(2)(NO(3))(2)] (4) and [Cu(TBZH)(O(2)C-CH(2)CH(2)-CO(2))] (5), respectively. The TBZH acts as a neutral chelating ligand in 3-5. Molecular structures of 1 and 3 were determined crystallographically. In 1, the asymmetric unit contains one TBZH(2)(+) cation and one NO(3)(-) anion. The structure of 3 comprises a five coordinate copper centre with the metal bound to two chelating TBZH ligands and one chloride. The geometry is best described as trigonal bipyramidal. Hydrogen bonding connects the complex cation with the uncoordinated chloride anion and the water and ethanol solvate molecules. Compound 1 and the copper complexes 2-5, the metal free ligands and a number of simple copper(II) salts were each tested for their ability to inhibit the growth of Candida albicans. The metal free TBZH and its nitrate salt (1) exhibited very poor activity. Complex 2, in which the TBZH is present as an anionic ligand (TBZ(-)), exhibits moderate activity towards the pathogen. Chelation of the neutral TBZH to copper centres (complexes 3-5) results in potent anti-candida activity. The dimethyl sulphoxide (DMSO) soluble complexes 3 and 4, along with metal free TBZH were assessed for their cancer chemotherapeutic potential towards two human epithelial-derived cancer model cell lines. Complexes 3 and 4 displayed similar dose-dependent cytotoxicity in both cell lines with IC(50) values of approximately 50 microM, which were found to be significantly lower than that for metal free TBZH.

  11. Mononuclear [(BP)(2)MX](n+) (M = Cu(2+), Co(2+), Zn(2+); X = OH(2), Cl(-)) complexes with a new biphenyl appended N-bidentate ligand: structural, spectroscopic, solution equilibrium and ligand dynamic studies.

    Science.gov (United States)

    Sabiah, Shahulhameed; Varghese, Babu; Murthy, Narasimha N

    2009-11-28

    A new series of five-coordinate [(BP)2MX]n+ complexes, (where X = OH2, M = Zn(II) (1), Cu(II) (2); X = Cl-, M = Cu(II) (3), Co(II) (4)) with a new bidentate chelating ligand [{N,N(1,1'-biphenyl-2,2'-dimethylene)-N(2-pyridyl methyl)} amine] with a biphenyl group (BP), have been synthesized and characterized by X-ray crystal structure and combined spectroscopic methods. They display unique trigonal bipyramidal (TBP) geometry, influenced by the bidentate ligand. The Zn(II) complex 1 reveals ligand dynamics due to an atropisomeric biphenyl moiety as indicated by variable temperature (VT) proton NMR spectroscopy. The calculated free energy for the inversion of the bridged biphenyl is approximately 13.08 kcal mol-1 (Tc = 273 K, Delta(nu) = 82.8 Hz, J = 8.7 Hz). The absorption spectra of Cu(II) complexes 2 and 3, in CH2Cl2 display greatly enhanced d-d bands (800-950 nm, epsilon>500 M-1 cm-1). On the other hand, complex 2 in N,N-dimethylformamide (DMF) showed almost 50% reduction in absorption intensity as DMF, a coordinating solvent, displaces the weakly-coordinated tertiary amine-nitrogens of the ligand and this competitive binding was studied by electronic absorption spectroscopy. When the mononuclear copper aqua complex 2 was treated with a base, a dicopper dihydroxide complex, [{(BP)Cu}2(mu-OH)2]2+, (2a) was obtained. The same phenomenon was also observed with chloro complex 3 when treated with a base. This mono-dicopper equilibrium and conversion of 2 --> 2a was monitored by UV-vis spectroscopy. Copper(II) complexes 2 and 3 displayed reverse EPR spectra consistent with the TBP geometry. Cyclic voltammetry of 2 and 3 in DMF showed an irreversible redox wave owing to Cu(II)/Cu(I) of five and four-coordinate species. The solution magnetic moment values of 1.76, 1.81 and 4.47 microB for 2, 3 and 4, respectively, are in agreement with Cu(II) (S = 1/2) and Co(II) (S = 3/2) high-spin configurations. The 1H NMR of 4 displays sharp but hyperfine shifted signals for the ligand

  12. Synthesis, characterization, and X-ray crystal structures of cyclam derivatives. 5. Copper(II) binding studies of a pyridine-strapped 5,12-dioxocyclam-based macrobicycle.

    Science.gov (United States)

    Meyer, Michel; Frémond, Laurent; Espinosa, Enrique; Guilard, Roger; Ou, Zhongping; Kadish, Karl M

    2004-09-06

    The copper(II) binding properties of the macrobicyclic diamide 1,9,12,18,22-pentaazatricyclo[7.6.6.1(3,7)]docosa-3,5,7(22)-triene-13,19-dione (L1) have been fully investigated by spectroscopic (IR, UV-vis, EPR, MALDI-TOF MS), X-ray diffraction, potentiometric, electrochemical, and spectroelectrochemical methods. This constrained receptor possesses a hemispherical cavity created by cross-bridging the 1 and 8 positions of trans-dioxocyclam (1,4,8,11-tetraazacyclotetradecane-5,12-dione, L2) with a 2,6-pyridyl strap. Treatment of L1 with a copper salt in methanol produces a red complex of [Cu(L1H(-1))]+ formula in which the copper atom is embedded in a 13-membered ring and coordinated by both amines as well as the pyridine and one deprotonated amide nitrogen atoms. Infrared spectroscopy provides evidence for protonation of the carbonyl oxygen atom belonging to the copper-bound amide of [Cu(L1H(-1))]+ under strongly acidic conditions. The resulting conversion of the amidate into an iminol group highlights the inert character of the corresponding complexes, which do not dissociate at low pH values. In contrast, both secondary amides of L1 deprotonate in the presence of a weak base, thus affording a blue pentacoordinated [Cu(L1H(-2))] compound where the copper atom sits in the center of the 14-membered dioxocyclam fragment. In aqueous solution, both complexes undergo a pH-driven (pK(a) = 8.73(2)) molecular reorganization, which is reminiscent of a glider motion. The copper(II) cation switches rapidly and reversibly from a four-coordinate flattened tetrahedral arrangement of the donor atoms in the red species to a five-coordinate environment in the blue species, which is intermediate between a square pyramid and a trigonal bipyramid. Conversion of the red to the blue form was also demonstrated to occur upon reduction of [Cu(L1H(-1))]+ by cyclic voltammetry (E(pc) = -0.64 V/SCE in CH(3)CN).

  13. Periodic trends within a series of five-coordinate thiolate-ligated [MII(SMe2N4(tren))]+ (M = Mn, Fe, Co, Ni, Cu, Zn) complexes, including a rare example of a stable CuII-thiolate.

    Science.gov (United States)

    Brines, Lisa M; Shearer, Jason; Fender, Jessica K; Schweitzer, Dirk; Shoner, Steven C; Barnhart, David; Kaminsky, Werner; Lovell, Scott; Kovacs, Julie A

    2007-10-29

    A series of five-coordinate thiolate-ligated complexes [M(II)(tren)N4S(Me2)]+ (M = Mn, Fe, Co, Ni, Cu, Zn; tren = tris(2-aminoethyl)amine) are reported, and their structural, electronic, and magnetic properties are compared. Isolation of dimeric [Ni(II)(SN4(tren)-RS(dang))]2 ("dang"= dangling, uncoordinated thiolate supported by H bonds), using the less bulky [(tren)N4S](1-) ligand, pointed to the need for gem-dimethyls adjacent to the sulfur to sterically prevent dimerization. All of the gem-dimethyl derivatized complexes are monomeric and, with the exception of [Ni(II)(S(Me2)N4(tren)]+, are isostructural and adopt a tetragonally distorted trigonal bipyramidal geometry favored by ligand constraints. The nickel complex uniquely adopts an approximately ideal square pyramidal geometry and resembles the active site of Ni-superoxide dismutase (Ni-SOD). Even in coordinating solvents such as MeCN, only five-coordinate structures are observed. The MII-S thiolate bonds systematically decrease in length across the series (Mn-S > Fe-S > Co-S > Ni-S approximately Cu-S complex, [Cu(II)(S(Me2)N4(tren)]+, represents a rare example of a stable CuII-thiolate, and models the perturbed "green" copper site of nitrite reductase. In contrast to the intensely colored, low-spin Fe(III)-thiolates, the M(II)-thiolates described herein are colorless to moderately colored and high-spin (in cases where more than one spin-state is possible), reflecting the poorer energy match between the metal d- and sulfur orbitals upon reduction of the metal ion. As the d-orbitals drop in energy proceeding across the across the series M(2+) (M= Mn, Fe, Co, Ni, Cu), the sulfur-to-metal charge-transfer transition moves into the visible region, and the redox potentials cathodically shift. The reduced M(+1) oxidation state is only accessible with copper, and the more oxidized M(+4) oxidation state is only accessible for manganese.

  14. Monofluoride bridged, binuclear metallacycles of first row transition metals supported by third generation bis(1-pyrazolyl)methane ligands: unusual magnetic properties.

    Science.gov (United States)

    Reger, Daniel L; Foley, Elizabeth A; Watson, Russell P; Pellechia, Perry J; Smith, Mark D; Grandjean, Fernande; Long, Gary J

    2009-11-16

    The reaction of M(BF(4))(2).xH(2)O, where M is Fe, Co, Cu, and Zn, and the ditopic, bis(pyrazolyl)methane ligand m-[CH(pz)(2)](2)C(6)H(4), L(m), where pz is a pyrazolyl ring, yields the monofluoride bridged, binuclear [M(2)(mu-F)(mu-L(m))(2)](BF(4))(3) complexes. In contrast, a similar reaction of L(m) with Ni(BF(4))(2).6H(2)O yields dibridged [Ni(2)(mu-F)(2)(mu-L(m))(2)](BF(4))(2). The solid state structures of seven [M(2)(mu-F)(mu-L(m))(2)](BF(4))(3) complexes show that the divalent metal ion is in a five-coordinate, trigonal bipyramidal, coordination environment with either a linear or nearly linear M-F-M bridging arrangement. NMR results indicate that [Zn(2)(mu-F)(mu-L(m))(2)](BF(4))(3) retains its dimeric structure in solution. The [Ni(2)(mu-F)(2)(mu-L(m))(2)](BF(4))(2) complex has a dibridging fluoride structure that has a six-coordination environment about each nickel(II) ion. In the solid state, the [Fe(2)(mu-F)(mu-L(m))(2)](BF(4))(3) and [Co(2)(mu-F)(mu-L(m))(2)](BF(4))(3) complexes show weak intramolecular antiferromagnetic exchange coupling between the two metal(II) ions with J values of -10.4 and -0.67 cm(-1), respectively; there is no observed long-range magnetic order. Three different solvates of [Cu(2)(mu-F)(mu-L(m))(2)](BF(4))(3) are diamagnetic between 5 and 400 K, thus showing strong antiferromagnetic exchange interactions of -600 cm(-1) or more negative. Mossbauer spectra indicate that [Fe(2)(mu-F)(mu-L(m))(2)](BF(4))(3) exhibits no long-range magnetic order between 4.2 and 295 K and isomer shifts that are consistent with the presence of five-coordinate, high-spin iron(II).

  15. Oxovanadium alkoxides: Structure, reactivity, and sup 51 V NMR characteristics. Crystal and molecular structures of VO(OCH sub 2 CH sub 2 Cl) sub 3 and VOCl sub 2 (THF) sub 2 H sub 2 O

    Energy Technology Data Exchange (ETDEWEB)

    Priebsch, W.; Rehder, D. (Universitaet Hamburg (West Germany))

    1990-08-08

    The vanadyl esters VO(OR){sub 3} (R = Me, Et, Pr, iPr, sBu, tBu, CH{sub 2}CH{sub 2}F, CH{sub 2}CH{sub 2}Cl, CH{sub 2}CCl{sub 3}) have been prepared and their association properties in pentane investigated by {sup 51}V NMR. Limiting (low concentration) {delta}({sup 51}V) values depend on the bulk of R (highest {sup 51}V shielding for tBu). Shielding decreases with increasing concentration (more pronounced for small R groups), owing to the formation of oligomers, probably connected by {mu}-OR groups. The X-ray diffraction study of VO(OCH{sub 2}CH{sub 2}Cl){sub 3} reveals dimer association of molecules belonging to adjacent unit cells via long V-OR bonds (226.1 (2) pm), and a trigonal-bipyramidal geometry for each monomeric unit. From the reaction between VOCl{sub 3} and diols (glycol, 1,3-propanediol, 1,2-, 2,3-, 1,3-, and 1,4-butanediol), complexes are obtained that contain the {l brace}VOCl(OR){sub 2}{r brace} and {l brace}VOCl{sub 2}OR{r brace} moieties and the alcohol coordinated in the monofunctional or bifunctional (chelating and bridging) mode. The {sup 51}V NMR spectrum of VOCl{sub 2}OCH(Me)CH(Me)OH exhibits resolved {sup 51}V-{sup 35,37}Cl coupling: J({sup 51}V-{sup 35}Cl) = 100 Hz; J({sup 51}V-{sup 37}Cl) = 83 Hz. V{sup V}OCl{sub 2}(OCH{sub 2}CH{sub 2}CH{sub 2}OH) reacts with 1,4-butanediol to form V{sup IV}OCl{sub 2}(THF){sub 2}(OH{sub 2}). In the presence of COCL{sub 3}, THF undergoes ether splitting, chlorination, and coordination to vanadium to yield VOCl{sub 2}(OCH{sub 2}CH{sub 2}CH{sub 2}CH{sub 2}Cl). 35 refs., 7 figs., 7 tabs.

  16. Formation of a unique zinc carbamate by CO2 fixation: implications for the reactivity of tetra-azamacrocycle ligated Zn(II) complexes.

    Science.gov (United States)

    Notni, Johannes; Schenk, Stephan; Görls, Helmar; Breitzke, Hergen; Anders, Ernst

    2008-02-18

    The macrocyclic ligand [13]aneN 4 ( L1, 1,4,7,10-tetra-azacyclotridecane) was reacted with Zn(II) perchlorate and CO 2 in an alkaline methanol solution. It was found that, by means of subtle changes in reaction conditions, two types of complexes can be obtained: (a) the mu 3 carbonate complex 1, {[Zn( L1)] 3(mu 3-CO 3)}(ClO 4) 4, rhombohedral crystals, space group R3 c, with pentacoordinate zinc in a trigonal bipyramidal enviroment, and (b) an unprecedenced dimeric Zn(II) carbamate structure, 2, [Zn( L2)] 2(ClO 4) 2, monoclinic crystals, space group P2 1/ n. The ligand L2 (4-carboxyl-1,4,7,10-tetra-azacyclotridecane) is a carbamate derivative of L1, obtained by transformation of a hydrogen atom of one of the NH moieties into carbamate by means of CO 2 uptake. In compound 2, the distorted tetrahedral Zn(II) coordinates to the carbamate moiety in a monodentate manner. Most notably, carbamate formation can occur upon reaction of CO 2 with the [Zn L1] (2+) complex, which implicates that a Zn-N linkage is cleaved upon attack of CO 2. Since complexes of tetra-azamacrocycles and Zn(II) are routinely applied for enzyme model studies, this finding implies that the Zn-azamacrocycle moiety generally should no longer be considered to play always only an innocent role in reactions. Rather, its reactivity has to be taken into account in respective investigations. In the presence of water, 2 is transformed readily into carbonate 1. Both compounds have been additionally characterized by solid-state NMR and infrared spectroscopy. A thorough comparison of 1 with related azamacrocycle ligated zinc(II) carbonates as well as a discussion of plausible reaction paths for the formation of 2 are given. Furthermore, the infrared absorptions of the carbamate moiety have been assigned by calculating the vibrational modes of the carbamate complex using DFT methods and the vibrational spectroscopy calculation program package SNF.

  17. Möhnite, (NH4)K2Na(SO4)2, a new guano mineral from Pabellón de Pica, Chile

    Science.gov (United States)

    Chukanov, Nikita V.; Aksenov, Sergey M.; Rastsvetaeva, Ramiza K.; Pekov, Igor V.; Belakovskiy, Dmitry I.; Britvin, Sergey N.

    2015-10-01

    The new mineral möhnite, ideally (NH4)K2Na(SO4)2, the ammonium analogue of aphthitalite, is found in a guano deposit on the Pabellón de Pica mountain, near Chanabaya, Iquique Province, Tarapacá Region, Chile. It is associated with salammoniac, halite, joanneumite, natroxalate, nitratine, chanabayaite, and a clay mineral. Möhnite occurs as random aggregates and clusters of brown imperfect bipyramidal or spindle-shaped crystals. The mineral is brittle, with Mohs' hardness of 3; Dmeas is 2.4(1) g/cm3 and Dcalc is 2.461 g/cm3. The IR spectrum shows the presence of NH4 + cations (the bands at 1431, 3076 and 3240 cm-1). Möhnite is almost isotropic, optically neutral; ɛ = ω = 1.505(2). The chemical composition (electron-microprobe data, N determined by gas chromatography of products of ignition, H calculated by stoichiometry, wt%) is: (NH4)2O 7.99, Na2O 9.49, K2O 32.34, SO3 51.32, total 101.14. The empirical formula is (NH4)0.95Na0.95 K2.14S1.99O8. The crystal structure was solved and refined to R = 0.049 based on 241 unique reflections with I > 2σ( I). Möhnite is trigonal, space group P m1, a = 5.7402(3) Å, c = 7.435(1) Å, V = 212.16(4) Å3, Z = 1. The strongest reflections of the powder X-ray diffraction pattern [ d, Å ( I,%) ( hkl)] are: 4.955 (27) (100), 4.122 (37) (101, 011), 3.708 (29) (002), 2.969 (74) (102, 012), 2.861 (100) (110), 2.474 (20) (003), 2.060 (33) (022). The mineral is named in honour of the German amateur mineralogist Gerhard Möhn (born 1959).

  18. Structure and spin state of nonheme FeIVO complexes depending on temperature: predictive insights from DFT calculations and experiments† †Electronic supplementary information (ESI) available: Methods section, Tables S1–S8, all the data for DFT calculations (Tables S9–S53 for energies, Mulliken spin density distribution, and selected geometries), and coordinates. See DOI: 10.1039/c7sc01738c Click here for additional data file.

    Science.gov (United States)

    Lee, Na Young; Mandal, Debasish; Bae, Seong Hee; Seo, Mi Sook; Lee, Yong-Min; Shaik, Sason

    2017-01-01

    The spin states (S = 1 and S = 2) of nonheme FeIVO intermediates are believed to play an important role in determining their chemical properties in enzymatic and biomimetic reactions. However, it is almost impossible to investigate the spin state effect of nonheme FeIVO species experimentally, since FeIVO models having the S = 1 and S = 2 spin states at the same time neither exist nor can be synthesized. However, recent synthesis of an FeIVO complex with an S = 1 spin state (triplet), [(Me3NTB)FeIVO]2+ (1), and a structurally similar FeIVO complex but with an S = 2 spin state (quintet), [(TQA)FeIVO]2+ (2), has allowed us to compare their reactivities at 233 K. In the present study, we show that structural variants control the spin-state selectivity and reactivity of nonheme FeIVO complexes. While 1 and 2 were proposed to be in an octahedral geometry based on DFT calculations and spectroscopic characterization done at 4 K, further DFT calculations show that these species may well assume a trigonal bipyramidal structure by losing one coordinated solvent ligand at 233 K. Thus, the present study demonstrates that the structure and spin state of nonheme FeIVO complexes can be different at different temperatures; therefore, the structural and/or spin state information obtained at 4 K should be carefully used at a higher temperature (e.g., 233 K). In addition to 1 and 2, [(TPA)FeIVO]2+ (3) with an S = 1 spin state, whose spin state was determined spectroscopically and theoretically at 233 K, is included in this study to compare the chemical properties of S = 1 and S = 2 FeIVO complexes. The present results add another dimension to the discussion of the reactivites of nonheme FeIVO species, in which the structural preference and spin state of nonheme FeIVO species can vary depending on temperature. PMID:28970926

  19. Regio- and stereo-selective polymerization of 1,3-butadiene catalyzed by phosphorus–nitrogen PN3-pincer cobalt(ii) complexes

    KAUST Repository

    Gong, Dirong

    2016-11-11

    A new family of cobalt complexes (CoCl2-H, CoCl2-Me, CoCl2-iPr, CoBr2-H, CoBr2-Me, CoBr2-iPr, CoI2-H, CoI2-Me, and CoI2-iPr) supported by a PN3 ligand (6-(N,N′-di-t-butylphosphino)-2-pyrazol-yl-aminopyridine) have been prepared and fully characterized by FT-IR, elemental analysis, and X-ray analysis. The X-ray analysis reveals a trigonal bipyramidal conformation in the solid state for all representative complexes, CoCl2-H, CoBr2-H, CoBr2-iPr and CoI2-Me. The cobalt center is chelated by the PN3 ligand through the pyridinyl nitrogen, the pyrazol nitrogen and the phosphorus donor, with a long Co-P bond distance indicating a labile character. On activation with AlEt2Cl, Al2Et3Cl3, MAO, [Ph3C]+[B(C6F5)4]-/AliBu3 or AliBu3, cis-1,4 selective butadiene polymerization was achieved with up to 98.6% selectivity. The polymerization results show that the cis-1,4 selectivity is influenced by the steric hindrance, increasing with the bulkiness of the substituent groups (CoX2-iPr > CoX2-Me > CoX2-H) at the 3,5-positions of the pyrazole moiety, together with a slight decrease in activity. The activity changes in the order CoCl2L ≈ CoBr2L > CoI2L (for the same ligand L) when MAO is used as the activator, while the high level of cis-1,4 selectivity is maintained. It is possible to switch the selectivity from cis-1,4 to syndiotactic-1,2 by adding PPh3 © The Royal Society of Chemistry.

  20. Structural study of modified Bi{sub 4}V{sub 2}O{sub 10+{delta}} phases ({delta} = 0, 0.5, 1): Influence of antimony contribution

    Energy Technology Data Exchange (ETDEWEB)

    Sorokina, S.; Enjalbert, R.; Baules, P.; Galy, J. [CNRS, Toulouse (France). Centre d`Elaboration de Materiaux et d`Etudes Structurales; Castro, A. [CSIC, Cantoblanco, Madrid (Spain). Inst. de Ciencia de Materiales

    1999-05-01

    Three solid solutions of general composition Bi{sub 4{minus}x}Sb{sub x}V{sub 2}O{sub 10}, Bi{sub 4}V{sub 2{minus}y}{sup 4+}V{sub y}{sup 5+}O{sub 10+y/2}, and Bi{sub 4}V{sub 2{minus}z}Sb{sub z}O{sub 11} have been investigated in the fivefold Bi{sub 2}O{sub 3}-V{sub 2}O{sub 5}-V{sub 2}O{sub 4}-Sb{sub 2}O{sub 3}-Sb{sub 2}O{sub 5} system. These oxides have been characterized by X-ray diffraction and electron microscopy techniques. Single phases have been isolated for values ranging from 0 to x, z = 0.8 and y = 2. Single crystals of Bi{sub 3.2}Sb{sub 0.8}V{sub 2}O{sub 10}, Bi{sub 4}V{sub 2}O{sub 10.5}, and Bi{sub 4}V{sub 1.2}Sb{sub 0.8}O{sub 11} have been grown and their structures determined by X-ray diffraction methods. The three oxides crystallize in the orthorhombic system, space groups F222, Amam, and Fmmm, respectively. Their structures keep the classical two-dimensional array of Aurivillius-like oxides with (Bi, Sb)-O layers interleaved with (V, Sb)-O sheets. It has been found that Sb{sup 3+} is introduced into the bismuth layer, due to its similar sterical behavior, by the presence of a 5s{sup 2} lone pair associated with Sb{sup 3+} and 6s{sup 2} associated with Bi{sup 3+}, whereas Sb{sup 5+} substitutes for the V{sup 5+} cation. All of the substitutions carried out mainly act on the vanadium layer, which can accommodate different coordination polyhedra for cations: tetrahedra for V{sup 5+}, square pyramids and distorted trigonal bipyramids or octahedra for V{sup 4+} and V{sup 5+}, and octahedra for Sb{sup 5+}. This fact can be related to the electrical properties, such as high ionic conduction and ferroelectricity, shown by these types of materials.

  1. R2NH2C2O4SnC2O4SnBu3, (R2NH24(C2O43(SnR’32 (R = Cy, i-Bu; R’ = Me, Bu AND SOME MIXED ORGANO- AND HALOTIN (IV OXALATO NEW MOETIES CONTAINING COMPLEXES: SYNTHESIS, INFRARED, MOSSBAUER AND NMR STUDIES

    Directory of Open Access Journals (Sweden)

    YAYA SOW

    2015-07-01

    Full Text Available On allowing (Cy2NH22C2O4∙2H2O to react with SnBu3Cl or SnMe3Cl, i-Bu2NH2HC2O4 with SnBu3Cl, (Bu2NH22C2O4 with SnMe3Cl, (i-Bu2NH22C2O4 with SnPh2Cl2, a mixture of i-Bu2NH22C2O4 and (Me4N2C2O4 with SnPh2Cl2, (Pr2NH22C2O4 with SnPh3Cl, the oxalato derivatives and complexes Cy2NH2C2O4SnBu3.3H2O∙1/4Cy2NH2Cl, i-Bu2NH2C2O4SnBu3∙1/2(i-Bu2NH22C2O4,y2NH2C2O4SnMe3∙1/2(Cy2NH22C2O4, Sn(C2O42∙[C2O4(SnMe3∙H2O2]∙2EtOH∙1/4[(Bu2NH22C2O4],(i-Bu2NH22 C2O4∙ 2SnPh2Cl2∙SnCl4∙4(i-Bu2NH2OH∙2(i-Bu2NH2Cl, 2[SnPh2Cl4(i-Bu2NH22]∙ SnCl2C2O4∙4i-Bu2NH2Cl and 2[Pr2NH2C2O4SnPh3]∙(Pr2NH22C2O4∙SnCl4∙ 2Pr2NH2Cl were obtained. Double chain, two metallic components and a dimeric structures are suggested with trans coordinated SnMe3 residues, these chains being connected through R2NH2+ (R = Cy, i-Bu only or by (R2NH22C2O4 bridges. The oxalate behaves as a monochelating, a bridging, an only hydrogen bonding involved or monodentate and H bond involved ligand. The environments around the tin (IV centres are cis or trans trigonal bipyramidal, tetrahedral or octahedral. Supramolecular architectures may be obtained when extra hydrogen bonds are possible.

  2. Quercetinase QueD of Streptomyces sp. FLA, a monocupin dioxygenase with a preference for nickel and cobalt.

    Science.gov (United States)

    Merkens, Hedda; Kappl, Reinhard; Jakob, Roman P; Schmid, Franz X; Fetzner, Susanne

    2008-11-18

    Quercetinase (QueD) of Streptomyces sp. FLA is an enzyme of the monocupin family and catalyzes the 2,4-dioxygenolytic cleavage of the flavonol quercetin. After expression of the queD gene in Escherichia coli, high specific QueD activity was found in crude cell extracts when the growth medium was supplemented with NiCl 2 or CoCl 2, but not when Mn (2+), Fe (2+), Cu (2+), or Zn (2+) was added. The metal occupancy of Ni- and Co-QueD purified from these cells was trigonal-bipyramidal coordination geometry. Anoxic binding of quercetin to QueD drastically altered the hyperfine pattern at g approximately 6 without changing the valence state of the Co(II) center and elicited a hypsochromic shift of UV-vis absorption band I of quercetin. On the basis of spectroscopic data, and considering the organic chemistry of flavonols, a nonredox role of the metal center in catalysis is discussed.

  3. Valence shell charge concentrations at pentacoordinate d0 transition-metal centers: non-VSEPR structures of Me2NbCl3 and Me3NbCl2.

    Science.gov (United States)

    McGrady, G Sean; Haaland, Arne; Verne, Hans Peter; Volden, Hans Vidar; Downs, Anthony J; Shorokhov, Dmitry; Eickerling, Georg; Scherer, Wolfgang

    2005-08-19

    The molecular structures of the monomeric, pentacoordinated methylchloroniobium(IV) compounds Me3NbCl2 and Me2NbCl3 have been determined by gas electron diffraction (GED) and density functional theory (DFT) calculations, and, for Me3NbCl2, by single crystal X-ray diffraction. Each of the molecules is found to have a heavy-atom skeleton in the form of a trigonal bipyramid (TBP) with Cl atoms in the axial positions, in accord with their vibrational spectra. The TBP is somewhat distorted in the case of Me2NbCl3 with the two axial Nb--Cl bonds bent away from the equatorial, slightly shorter Nb--Cl bond. In the case of Me3NbCl2, moreover, the X-ray model suggests structural distortions away from the idealized C3h geometry, in line with the results of quantum chemical calculations. Structure optimizations by DFT calculations and least-squares refinement to the GED data yield the following structural parameters (calcd/exptl; eq=equatorial; ax=axial; distances in A, angles in degrees; average values in brackets): Me3NbCl2, in C(3v) symmetry, Nb--Cl 2.370/2.319(3), Nb--C 2.173/2.152(4), C--H 1.096/1.124(5), angle-spherical NbCH 109.3/105.2(8), angle-spherical ClNbC 92.2/93.3(2), angle-spherical CNbC 119.9/119.7(1); Me2NbCl3, in C(2v) symmetry, Nb--Cl(ax) 2.361/2.304(5), Nb--Cl(eq) 2.321/2.288(9), Nb--C 2.180/2.135(9), C--H 1.094/1.12(1), angle-spherical Cl(ax)NbCl(eq) 98.5/96.5(6), angle-spherical CNbC 121.0/114(2), angle-spherical NbCH 108.9/109(2). The electronic structures of Me2NbCl3 and Me3NbC(2 have been explored by rigorous analysis of both the wavefunction and the topology of the electron density, employing DFT calculations. Hence the structures of these compounds are shown to reflect repulsion between the Nb--C and Nb--Cl bonding electron density and charge concentrations induced by the methyl ligands in the valence shell of the Nb atom and arising mainly from use of Nb(4d) functions in the Nb--C bonds.

  4. Mechanisms and rates of proton transfer to coordinated carboxydithioates: studies on [Ni(S2CR){PhP(CH2CH2PPh2)2}](+) (R = Me, Et, Bu(n) or Ph).

    Science.gov (United States)

    Alwaaly, Ahmed; Clegg, William; Henderson, Richard A; Probert, Michael R; Waddell, Paul G

    2015-02-21

    The complexes [Ni(S2CR)(triphos)]BPh4 (R = Me, Et, Bu(n) or Ph; triphos = PhP{CH2CH2PPh2}2) have been prepared and characterised. X-ray crystallography (for R = Et, Ph, C6H4Me-4, C6H4OMe-4 and C6H4Cl-4) shows that the geometry of the five-coordinate nickel in the cation is best described as distorted trigonal bipyramidal, containing a bidentate carboxydithioate ligand with the two sulfur atoms spanning axial and equatorial sites, the other axial site being occupied by the central phosphorus of triphos. The reactions of [Ni(S2CR)(triphos)](+) with mixtures of HCl and Cl(-) in MeCN to form equilibrium solutions containing [Ni(SH(S)CR)(triphos)](2+) have been studied using stopped-flow spectrophotometry. The kinetics show that proton transfer is slower than the diffusion-controlled limit and involves at least two coupled equilibria. The first step involves the rapid association between [Ni(S2CR)(triphos)](+) and HCl to form the hydrogen-bonded precursor, {[Ni(S2CR)(triphos)](+)HCl} (K) and this is followed by the intramolecular proton transfer (k) to produce [Ni(SH(S)CR)(triphos)](2+). In the reaction of [Ni(S2CMe)(triphos)](+) the rate law is consistent with the carboxydithioate ligand undergoing chelate ring-opening after protonation. It seems likely that chelate ring-opening occurs for all [Ni(S2CR)(triphos)](+), but only with [Ni(S2CMe)(triphos)](+) is the protonation step sufficiently fast that chelate ring-opening is rate-limiting. With all other systems, proton transfer is rate-limiting. DFT calculations indicate that protonation can occur at either sulfur atom, but only protonation at the equatorial sulfur results in chelate ring-opening. The ways in which protonation of either sulfur atom complicates the analyses and interpretation of the kinetics are discussed.

  5. Synthesis and characterization of two polyoxometalates consisting of different Cu-ligand hydrogen phosphate units

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Jinshuang; Zhao, Xiaofang; Huang, Jiao; Gong, Kaining; Han, Zhangang, E-mail: hanzg116@126.com; Zhai, Xueliang, E-mail: xlzhai253@mail.hebtu.edu.cn

    2014-03-15

    Two polyoxometalates [(Cu-mbpy){sub 4}(HPO{sub 4}){sub 2}(H{sub 2}O){sub 2}][PMo{sub 12}O{sub 40}]·H{sub 2}O (1) and [(Cu-mbpy){sub 6}(HPO{sub 4}){sub 4}][PW{sub 12}O{sub 40}]·4H{sub 2}O (2) (mbpy=4,4'-dimethyl-2,2'-dipyridyl in 1; 5,5″-dimethyl-2,2'-dipyridyl in 2) have been synthesized and characterized by IR, X-ray powder diffraction, TG analysis and electrochemical property. The structural features of 1–2 are in their cationic moieties consisting of different linkages of [Cu-mbpy]{sup 2+} and HPO{sub 4}{sup 2−} groups. In 1 four Cu-mbpy bridged by two HPO{sub 4}{sup 2−} ions form a discrete cluster with an interesting octahedron of (Cu{sub 4}P{sub 2}), while in 2 Cu-mbpy fragments are bridged by HPO{sub 4}{sup 2−} ions into 1D structure consisting of trigonal bipyramidal polyhedra of (Cu{sub 3}P{sub 2}). Photocatalytic experiments indicate that compounds 1 and 2 are actively photocatalytic for degradation of methyl orange in the presence of H{sub 2}O{sub 2} under UV light irradiation. -- Graphical abstract: Two polyoxometalate-based supramolecular compounds consisting of different linkages based on Cu-ligand and HPO{sub 4}{sup 2−} groups have been synthesized and characterized. The photocatalytic activity are studied. Highlights: • Two polyoxometalate-based supramolecular compounds consisting of different linkages based on Cu-ligand and HPO{sub 4}{sup 2−} groups have been synthesized. • Hydrogen bonding and π…π interactions play important roles in constructing crystal supramolecular frameworks. • Two compounds represent a high photocatalytic activity in the degradation of methyl orange.

  6. Varying coordination modes and magnetic properties of copper(II) complexes with diazamesocyclic ligands by altering additional donor pendants on 1,5-diazacyclooctane.

    Science.gov (United States)

    Bu, X H; Du, M; Shang, Z L; Zhang, R H; Liao, D Z; Shionoya, M; Clifford, T

    2000-09-18

    A series of new diazamesocyclic ligands based on a diazamesocycle, 1,5-diazacyclooctane (DACO), functionalized by additional donor groups--1,5-bis(N-1-methylimidazol-2-ylmethyl)-1,5- diazacyclooctane (L1), 1-(2-hydroxybenzyl)-1,5-diazacyclooctane (HL2), 1,5-bis(2-hydroxybenzyl)-1,5-diazacyclooctane (H2L3), and 1-(N-1-methylimidazol-2-ylmethyl)-1,5-diazacyclooctane (L4)--and their Cu(II) complexes have been synthesized and characterized. Single-crystal X-ray diffraction analysis of the four Cu(II) complexes revealed that L1 forms a five-coordinate mononuclear complex, HL2 a N3- mu-bridged binuclear complex, H2L3 an oxygen mu-bridged trinuclear complex, and L4 a one-dimensional zigzag coordination polymeric complex with Cu(II). [CuL1ClO4](ClO4) (I): a = 12.194(2) A, b = 13.351(3) A, c = 14.473(3) A, beta = 107.10(3) degrees, Z = 4. [CuL2(N3)]2 (II): a = 8.1864(6) A, b = 18.141(2) A, c = 9.3307(7) A, beta = 103.662(6) degrees, Z = 2. [Cu3(L3)2Cl2] (III): a = 10.7296(13) A, b = 13.7707(17) A, c = 13.5523(17) A, beta = 106.350(3) degrees, Z = 2. ([CuL4Cl]2ClO4) infinity (IV): a = 7.279(1) A, b = 23.695(5) A, c = 19.308(4) A, beta = 100.28(3) degrees, Z = 8. All four complexes crystallize in the monoclinic crystal system with the P2(1)/c space group, and each Cu(II) center coordinated with DACO is pentacoordinated with a distorted square-pyramidal or trigonal-bipyrimidal coordination environment. In complex IV, the binuclear cation unit [CuL4Cl]2(2+) constitutes the fundamental building block of an infinite alternating zigzag chain structure, and the binuclear unit contains two types of geometries around the Cu(II) centers: the Cu(1) center is a distorted square-pyramidal environment, while the Cu(2) is a distorted trigonal-bipyramidal coordination environment. To the best of our knowledge, this is the first Cu(II) complex of a diazamesocyclic ligand with an infinite polymeric structure. The magnetic properties of complexes II, III, and IV have been investigated by

  7. Syntheses, structural analyses and redox kinetics of four-coordinate [CuL2]2+ and five-coordinate [CuL2(solvent)]2+ complexes (L = 6,6'-dimethyl-2,2'-bipyridine or 2,9-dimethyl-1,10-phenanthroline): completely gated reduction reaction of [Cu(dmp)2]2+ in nitromethane.

    Science.gov (United States)

    Itoh, Sumitaka; Kishikawa, Nobuyuki; Suzuki, Takayoshi; Takagi, Hideo D

    2005-03-21

    [Cu(2,9-dimethyl-1,10-phenanthroline)(2)](2+) and [Cu(6,6'-dimethyl-2,2'-bipyridine)(2)](2+/+) complexes with no coordinated solvent molecule were synthesized and the crystal structures were analyzed: the coordination geometry around the Cu(i) center was in the D(2d) symmetry while a D(2) structure was observed for the four-coordinate Cu(ii) complexes. Coordination of a water or an acetonitrile molecule was found in the trigonal plane of the five-coordinate Cu(ii) complex in the Tbp(trigonal bipyramidal) structure. Spectrophotometric analyses revealed that the D(2) structure of the Cu(ii) complex was retained in nitromethane, although a five-coordinate Tbp species (green in color), was readily formed upon dissolution of the solid (reddish brown) in acetonitrile. The electron self-exchange reaction between D(2d)-Cu(I) and D(2)-Cu(II), observed by the NMR method, was very rapid with k(ex)=(1.1 +/- 0.2) x 10(5) kg mol(-1) s(-1) at 25 degrees C (DeltaH*= 15.6 +/- 1.3 kJ mol(-1) and DeltaS*=-96 +/- 4 J mol(-1) K(-1)), which was more than 10 times larger than that reported for the self-exchange reaction between D(2d)-Cu(I) and Tbp-Cu(II) in acetonitrile. The cross reduction reactions of D(2)-Cu(ii) by ferrocene and decamethylferrocene in nitromethane exhibited a completely gated behavior, while the oxidation reaction of D(2d)-Cu(i) by [Ni(1,4,7-triazacyclononane)(2)](3+) in nitromethane estimated an identically large self-exchange rate constant to that directly obtained by the NMR method. The electron self-exchange rate constant estimated from the oxidation cross reaction in 50% v/v acetonitrile-nitromethane mixture was 10 times smaller than that observed in pure nitromethane. On the basis of the Principle of the Least Motion (PLM) and the Symmetry Rules, it was concluded that gated behaviors observed for the reduction reactions of the five-coordinate Cu(ii)-polypyridine complexes are related to the high-energy C(2v)--> D(2d) conformational change around Cu(ii), and that

  8. Lõhmuse tutvuskond toetab Eesti IT-sektorit / Viktoria Korpan

    Index Scriptorium Estoniae

    Korpan, Viktoria, 1976-

    1999-01-01

    Investeerimispank Lõhmus, Haavel & Viisemann (LHV) kavandab aktsiaemissiooni ASi New Economy Ventures (NEV) jaoks, et teha selle kaudu investeeringuid infotehnoloogiafirmadesse. Sama plaan on investeerimisfirmal Trigon Capital

  9. SYNTHESIS, CRYSTAL STRUCTURE, SPECTROSCOPY PROPERTIES AND POTENTIAL ANTIMICROBIAL POTENTIALITIES OF A NEW SYNTHETIC COMPOUND: AMINO- CHLOROPYRIDINIUM DIAQUA DIOXALATO IRON(III)

    National Research Council Canada - National Science Library

    Jawher Abdelhak; Essghaier Badiaa; Toukebri Nourchene; Amani Naouar; Rebib Hanene; Mohamed Faouzi Zid; Najla Sadfi-Zouaoui

    .... It has been characterized by IR and UV-VIS spectra and thermal analysis (TG and DTA). In this compound, the iron ion has a slightly distorted square bipyramidal environment, coordinated by two chelating oxalate ion and two water molecules...

  10. Eesti fond rahastab Vene infotehnoloogiat / Andres Reimer

    Index Scriptorium Estoniae

    Reimer, Andres

    2006-01-01

    Martinson Trigon Venture Partners (MTVP) loob uue tarkvarainvesteeringute fondi, mis viib endise NSVL-i alale kuni 780 miljonit krooni, fond võtab sihiks kümmekond uut ettevõtet. MTVP esimese fondi investeeringutest. Fondide juhi Andres Susi selgitusi. Lisa: Martinson Trigon Venture Partners osalusega firmad; Vt. samas: Moskvas pole raha ja geeniused kohtunud

  11. Twinned low-temperature structures of tris(ethylenediamine)zinc(II) sulfate and tris(ethylenediamine)copper(II) sulfate

    NARCIS (Netherlands)

    Lutz, M.

    2010-01-01

    Tris(ethylenediamine)zinc(II) sulfate, [Zn(C2H8N2)3]SO4, (I), undergoes a reversible solid–solid phase transition during cooling, accompanied by a lowering of the symmetry from high-trigonal P31c to low-trigonal P3 and by merohedral twinning. The molecular symmetries of the cation and anion change

  12. Pocket Semiquinonate Complexes of Cobalt(II), Copper(II), and Zinc(II) Prepared with the Hydrotris(cumenylmethylpyrazolyl)borate Ligand.

    Science.gov (United States)

    Ruf, Michael; Noll, Bruce C.; Groner, Markus D.; Yee, Gordon T.; Pierpont, Cortlandt G.

    1997-10-08

    3,5-Di-tert-butyl-1,2-semiquinonate (3,5-DBSQ) complexes of Co(II), Cu(II), and Zn(II) have been prepared that contain the hydrotris(cumenylmethyl-pyrazolyl)borate (Tp(Cum,Me)) coligand. Tp(Cum,Me)Zn(3,5-DBSQ) and Tp(Cum,Me)Cu(3,5-DBSQ) were prepared by treating the parent hydroxide, Tp(Cum,Me)M(OH), M = Cu and Zn, with 3,5-di-tert-butylcatechol. Tp(Cum,Me)Co(3,5-DBSQ) was prepared by a reaction between (Tp(Cum,Me))(2)Co and 3,5-DBCat. The identity of (Tp(Cum,Me))(2)Co in this reaction was confirmed by a structure determination [(Tp(Cum,Me))(2)Co: orthorhombic, Pbcn, a = 17.7189(4) Å, b = 17.4806(3) Å, c = 25.7123(6) Å, V = 7964.1(3) Å(3), Z = 4, R(F) = 0.054]. Intersecting cumenyl substituents of the pyrazolylborate ligand encapsulate the Co(II) ion. Structural characterization on all three members of the Tp(Cum,Me)M(3,5-DBSQ) series has been carried out. The complexes of Co(II) and Zn(II) are isomorphous and isostructural [Tp(Cum,Me)Co(3,5-DBSQ): triclinic, P&onemacr;, a = 14.4631(2) Å, b = 18.5438(3) Å, c = 21.6142(2) Å, alpha = 79.8430(10) degrees, beta = 90.0900(10) degrees, gamma = 84.9900(10) degrees, V = 5683.45(13) Å(3), Z = 4, R(F) = 0.072; Tp(Cum,Me)Zn(3,5-DBSQ), triclinic, P&onemacr;, a = 14.261(3) Å, b = 18.760(7) Å, c = 21.710(4) Å, alpha = 80.049(12) degrees, beta = 89.853(8) degrees, gamma = 85.542(12) degrees, V = 5703(3) Å(3), Z = 4, R(F) = 0.064]. Tp(Cum,Me)Cu(3,5-DBSQ) [monoclinic, P2(1)/c, a = 19.3081(3) Å, b = 13.0291(2) Å, c = 21.4783(4) Å, beta = 102.8420(10) degrees, V = 5268.1(2) Å(3), Z = 4, R(F) = 0.071] has a distorted square pyramidal structure, the complexes of Zn and Co have structures that are closer to a trigonal bipyramid. Parent catecholate complexes of all three metals are unusually stable in air but undergo slow oxidation in solution to give the semiquinonate products characterized structurally. Copper(II) and SQ spins of Tp(Cum,Me)Cu(3,5-DBSQ) are located in orthogonal orbitals, and the complex has a S = 1 spin

  13. Cobalt as a Probe for Zinc in Metalloenzyme Model Compounds? A Comparison of Spectroscopic Features and Coordination Geometry of Four- and Five-Coordinate Complexes. Crystal and Molecular Structures of [Co(eta(3)-Tp(Ph))(eta(2)-Tp(Ph))], [(eta(3)-Tp(Ph))Zn(anthranilate)], and [(eta(3)-Tp(Ph))M(eta(2)-acac)] (Tp(Ph) = Hydrotris(3-phenylpyrazol-1-yl)borate, acac = Pentane-2,4-dionate, and M = Zn, Co).

    Science.gov (United States)

    Kremer-Aach, Andreas; Kläui, Wolfgang; Bell, Ralf; Strerath, Angela; Wunderlich, Hartmut; Mootz, Dietrich

    1997-04-09

    chloro complexes [(Tp(Ph))MCl] with sodium or potassium acetylacetonate leads to isotypic zinc and cobalt complexes [(eta(3)-Tp(Ph))M(eta(2)-acac)]. Both crystallize in the monoclinic space group P2(1)/c, with Z = 4, the zinc compound with a = 16.334(3) Å, b = 11.545(2) Å, c = 15.816(3) Å, beta = 94.77(1) degrees, V = 2972(1) Å(3), and R = 0.039 and the cobalt compound with a = 16.358(7) Å, b = 11.519(2) Å, c = 15.847(6) Å, beta = 95.30(3) degrees, V = 2973(2) Å(3), and R = 0.035. The structures are best described as slightly distorted trigonal bipyramids with the two axial positions occupied by one of the acetylacetonate O and one of the tripodal N donor atoms. Ligand profiles of Tp(Ph) and related ligands have been calculated to visualize the angular encumbrance of the ligands.

  14. Dinuclear Metallacycles with Single M-X-M Bridges (X = Cl-, Br-; M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)): Strong Antiferromagnetic Superexchange Interactions.

    Science.gov (United States)

    Reger, Daniel L; Pascui, Andrea E; Foley, Elizabeth A; Smith, Mark D; Jezierska, Julia; Wojciechowska, Agnieszka; Stoian, Sebastian A; Ozarowski, Andrew

    2017-03-06

    A series of monochloride-bridged, dinuclear metallacycles of the general formula [M2(μ-Cl)(μ-L)2](ClO4)3 have been prepared using the third-generation, ditopic bis(pyrazolyl)methane ligands L = m-bis[bis(1-pyrazolyl)methyl]benzene (Lm), M = Cu(II), Zn(II), and L = m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (Lm*), M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II). These complexes were synthesized from the direct reactions of M(ClO4)2·6H2O, MCl2, and the ligand, Lm or Lm*, in the appropriate stoichiometric amounts. Three analogous complexes of the formula [M2(μ-Cl)(μ-L)2](BF4)3, L = Lm, M = Cu(II), and L = Lm*, M = Co(II), Cu(II), were prepared from the reaction of [M2(μ-F)(μ-L)2](BF4)3 and (CH3)3SiCl. The bromide-bridged complex [Cu2(μ-Br)(μ-Lm*)2](ClO4)3 was prepared by the first method. Three acyclic complexes, [Co2(μ-Lm)μ-Cl4], [Co2(μ-Lm*)Cl4], and [Co2(μ-Lm*)Br4], were also prepared. The structures of all [M2(μ-X)(μ-L)2]3+ (X = Cl-, Br-) complexes have two ditopic bis(pyrazolyl)methane ligands bridging two metals in a metallacyclic arrangement. The fifth coordination site of the distorted trigonal bipyramidal metal centers is filled by a bridging halide ligand that has an unusual linear or nearly linear M-X-M angle. The NMR spectra of [Zn2(μ-Cl)(μ-Lm*)2](ClO4)3 and especially [Cd2(μ-Cl)(μ-Lm*)2](ClO4)3 demonstrate that the metallacycle structure is maintained in solution. Solid state magnetic susceptibility data for the copper(II) compounds show very strong antiferromagnetic exchange interactions, with -J values of 536 cm-1 for [Cu2(μ-Cl)(μ-Lm)2](ClO4)3·xCH3CN, 720 cm-1 for [Cu2(μ-Cl)(μ-Lm*)2](ClO4)3, and 945 cm-1 for [Cu2(μ-Br)(μ-Lm*)2](ClO4)3·2CH3CN. Smaller but still substantial antiferromagnetic interactions are observed with other first row transition metals, with -J values of 98 cm-1 for [Ni2(μ-Cl)(μ-Lm*)2](ClO4)3, 55 cm-1 for [Co2(μ-Cl)(μ-Lm*)2](ClO4)3, and 34 cm-1 for [Fe2(μ-Cl)(μ-Lm*)2](ClO4)3. EPR spectra of [Cu

  15. Synthesis, structure, and DNA cleavage properties of copper(II) complexes of 1,4,7-triazacyclononane ligands featuring pairs of guanidine pendants.

    Science.gov (United States)

    Tjioe, Linda; Joshi, Tanmaya; Brugger, Joël; Graham, Bim; Spiccia, Leone

    2011-01-17

    Two new ligands, L(1) and L(2), have been prepared via N-functionalization of 1,4,7-triazacyclononane (tacn) with pairs of ethyl- or propyl-guanidine pendants, respectively. The X-ray crystal structure of [CuL(1)](ClO4)2 (C1) isolated from basic solution (pH 9) indicates that a secondary amine nitrogen from each guanidine pendants coordinates to the copper(II) center in addition to the nitrogen atoms in the tacn macrocycle, resulting in a five-coordinate complex with intermediate square-pyramidal/trigonal bipyramidal geometry. The guanidines adopt an unusual coordination mode in that their amine nitrogen nearest to the tacn macrocycle binds to the copper(II) center, forming very stable five-membered chelate rings. A spectrophotometric pH titration established the pK(app) for the deprotonation and coordination of each guanidine group to be 3.98 and 5.72, and revealed that [CuL(1)](2+) is the only detectable species present in solution above pH ∼ 8. The solution speciation of the CuL(2) complex (C2) is more complex, with at least 5 deprotonation steps over the pH range 4-12.5, and mononuclear and binuclear complexes coexisting. Analysis of the spectrophotometric data provided apparent deprotonation constants, and suggests that solutions at pH ∼ 7.5 contain the maximum proportion of polynuclear complexes. Complex C1 exhibits virtually no cleavage activity toward the model phosphate diesters, bis(p-nitrophenyl)phosphate (BNPP) and 2-hydroxypropyl-p-nitrophenyl phosphate (HPNPP), while C2 exhibits moderate activity. For C2, the respective kobs values measured at pH 7.0 (7.24 (± 0.08) × 10(-5) s(-1) (BNPP at 50 °C) and 3.2 (± 0.3) × 10(-5) s(-1) (HPNPP at 25 °C)) are 40- and 10-times faster than [Cu(tacn)(OH2)2](2+) complex. Both complexes cleave supercoiled pBR 322 plasmid DNA, indicating that the guanidine pendants of [CuL(1)](2+) may have been displaced from the copper coordination sphere to allow for DNA binding and subsequent cleavage. The rate of DNA

  16. Characterization of ternary bivalent metal complexes with bis(2-hydroxyethyl)iminotris(hydroxymethy)methane (Bis?Tris) and the comparison of five crystal structures of Bis?Tris complexes*1

    Science.gov (United States)

    Inomata, Yoshie; Gochou, Yoshihiro; Nogami, Masanobu; Howell, F. Scott; Takeuchi, Toshio

    2004-09-01

    Eleven bivalent metal complexes with bis(2-hydroxyethyl)iminotris(hydroxymethy)methane (Bis-Tris:hihm): [M(hihm)(H 2O)]SO 4· nH 2O (M: Co, Ni, Cu, Zn), [MCl(hihm)]Cl· nH 2O (M: Co, Ni, Cu), and [M(HCOO)(hihm)](HCOO) (M: Co, Ni, Cu, Zn) have been prepared and characterized by using their infrared absorption and powder diffuse reflection spectra, magnetic susceptibility, thermal analysis and powder X-ray diffraction analysis. The crystal structures of [Ni(hihm)(H 2O)]SO 4·H 2O ( 2), [Cu(hihm)(H 2O)]SO 4 ( 3), [NiCl(hihm)]Cl·H 2O ( 6), [CuCl(hihm)]Cl ( 7) and [Co(HCOO)(hihm)](HCOO) ( 8) have been determined by single crystal X-ray diffraction analysis. The crystals of [Ni(hihm)(H 2O)]SO 4·H 2O ( 2) and [Cu(hihm)(H 2O)]SO 4 ( 3) are each orthorhombic with the space group P2 12 12 1 and Pna2 1. For both complexes, the metal atom is in a distorted octahedral geometry, ligated by four hydroxyl oxygen atoms, a nitrogen atom and a water molecule. [NiCl(hihm)]Cl·H 2O ( 6) is monoclinic with the space group P2 1/ n. For complex ( 6), the nickel atom is in a distorted octahedral geometry, ligated by four hydroxyl oxygen atoms, a nitrogen atom and a chloride ion. [CuCl(hihm)]Cl ( 7) is orthorhombic with the space group P2 12 12 1. Although in this copper(II) complex the copper atom is ligated by six atoms, it is more reasonable to think that the copper atom is in a trigonal bipyramidal geometry coordinated with five atoms: three hydroxyl oxygen atoms, a nitrogen atom and a chloride ion if the bond distances and angles surrounding the copper atom are taken into consideration. [Co(HCOO)(hihm)](HCOO) ( 8) is monoclinic with the space group P2 1. In cobalt(II) complex ( 8), the cobalt atom is in a distorted octahedral geometry, ligated by four hydroxyl oxygen atoms, a nitrogen atom and an oxygen atom of a formate ion. The structure of complex ( 8) is the same as the structure of [NiCl(hihm)]Cl·H 2O ( 6) except for the formate ion coordinating instead of the chloride ion. [M

  17. Allyl Ligand Reactivity in Tantalum(V) Compounds: Experimental and Computational Evidence for Allyl Transfer to the Formamidinate Ligand in fac-Ta(NMe2)3( 1-allyl)[iPrNC(H)NHiPr] via a Metallo-Claisen Rearrangement

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shih-Huang Huang [University of North Texas; Wang, Xiaoping [ORNL; Nesterov, Vladimir [University of North Texas; Hrovat, David A. [University of North Texas; Hall, Michael B. [Texas A& M University; Richmond, Michael G. [University of North Texas

    2011-01-01

    Treatment of TaCl(NMe{sub 2})4 (1) with allyl MgCl furnishes the allyl-substituted compound Ta(NMe{sub 2})4({eta}{sup 1}-allyl) (2) in moderate yield. The X-ray structure of 2 reveals a trigonal-bipyramidal geometry at the tantalum center with an equatorially situated {eta}{sup 1}-allyl moiety. VT {sup 1}H NMR measurements confirm that the molecule is fluxional in solution over the temperature range 298-193 K, and DFT calculations indicate that the time-averaged environment exhibited by the allyl moiety in fluid solution derives from a rapid {eta}{sup 1}-to-{eta}{sup 3} equilibration, with Ta(NMe{sub 2})4({eta}{sup 3}-allyl) serving as the transition state for this process. 1 reacts rapidly with the formamidine {sup i}PrNC(H)N{sup i}Pr to yield fac-TaCl(NMe{sub 2}){sub 3}[{sup i}PrNC(H)N{sup i}Pr] (5) and Me{sub 2}NH, and the tantalum product has been characterized by NMR spectroscopy and X-ray diffraction analysis. The five-coordinate compound Ta(NMe{sub 2}){sub 3}[{sup i}PrNCH(allyl)N{sup i}Pr] (7), whose origin is traced to the putative octahedral species fac-Ta(NMe{sub 2}){sub 3}({eta}{sup 1}-allyl)[{sup i}PrNC(H)N{sup i}Pr] (6), has been obtained from the reaction of 2 with {sup i}PrNC(H)N{sup i}Pr; 7 may also be prepared from the reaction of 5 with allylMgCl. The rearrangement of the allyl moiety in fac-Ta(NMe{sub 2}){sub 3}({eta}{sup 1}-allyl)[{sup i}PrNC(H)N{sup i}Pr] to the formamidinate carbon atom in 7 has been investigated by DFT calculations. Here the DFT calculations have provided crucial insight into the reaction mechanism and the composition of those transient species that do not lend themselves to direct spectroscopic observation. The computed barrier for this metallo-Claisen rearrangement is sensitive to the nature of the density functional employed, and the barrier computed using the meta-GGA TPSS functional provides the best agreement with the experimental conditions. The related alkenyl derivatives Ta(NMe{sub 2})4({eta}{sup 1}-3-butenyl) (3

  18. Tuning reactivity and mechanism in oxidation reactions by mononuclear nonheme iron(IV)-oxo complexes.

    Science.gov (United States)

    Nam, Wonwoo; Lee, Yong-Min; Fukuzumi, Shunichi

    2014-04-15

    (IV)-oxo complexes are significant in these reactions. However, the difference in spin states between nonheme iron(IV)-oxo complexes with an octahedral geometry (with an S = 1 intermediate-spin state) or a trigonal bipyramidal (TBP) geometry (with an S = 2 high-spin state) does not lead to a significant change in reactivity in biomimetic systems. Thus, the importance of the high-spin state of iron(IV)-oxo species in nonheme iron enzymes remains unexplained. We also discuss how the axial and equatorial ligands and binding of redox-inactive metal ions and protons to the iron-oxo moiety influence the reactivities of the nonheme iron(IV)-oxo complexes. We emphasize how these changes can enhance the oxidizing power of nonheme metal(IV)-oxo complexes in oxygen atom transfer and electron-transfer reactions remarkably. This Account demonstrates great advancements in the understanding of the chemistry of mononuclear nonheme iron(IV)-oxo intermediates within the last 10 years.

  19. Self-assembly of luminescent alkynyl-based platinum-cadmium complexes containing auxiliary diimine or terpyridine ligands.

    Science.gov (United States)

    Berenguer, Jesús R; Gil, Belén; Fernández, Julio; Forniés, Juan; Lalinde, Elena

    2009-06-15

    Reaction of different "Cd(N-N)(2)(2+)" (N-N = bpy, dmbpy, phen) or "Cd(trpy)(2+)" fragments with cis- or trans- (5) dianionic bis(alkynyl)platinate substrates [Pt(C(6)F(5))(2)(C[triple bond]CR)(2)](2-) (R = Ph a, Tol b) leads to the generation of novel bimetallic neutral Platinum-Cadmium derivatives, which show photoluminescence (PL) strongly influenced by the structure and the media. In complexes [cis-Pt(C(6)F(5))(2)(C[triple bond]CR)(2)Cd(N-N)(2)] (N-N = bpy (1), dmbpy (2), phen (3)), the dianionic cis-bis(alkynyl)platinate fragment interacts with the "Cd(N-N)(2)(+2)" unit mainly through both the C(alpha) atoms (d(Cd-C(alpha)) = 2.417(5)-2.554(5) A) and the Pt center (d(Pt-Cd) approximately 3.10 A); while in complexes [cis-Pt(C(6)F(5))(2)(C[triple bond]CR)(2)Cd(trpy)] (4), probably because of the presence of only three Cd-N bonds, the Pt-Cd interaction is enhanced (d(Pt-Cd) approximately 3.00 A), the Cd(II) atom being additionally solvated with acetone or H(2)O. By contrast, in complexes [trans-Pt(C(6)F(5))(2)(C[triple bond]CR)(2)Cd(bpy)(2)] (6) the Cd center is found to be in a distorted trigonal-bipyramid coordination, interacting with one of the Pt-C(alpha) bonds of the platina-bis(alkynyl) unit with very short Cd-C(alpha) (2.376(10) A) and Pt-Cd (2.8931(6) A) bond distances. Bimetallic complexes 1-4, having cis-configured platinum fragments, exhibit, in solid state, blue and/or green phosphorescence with contribution of close emissive states of different natures: metal (Pt, Cd) perturbed pi pi* intraligand (alkynyl, polyimine) manifolds mixed, to a greater (trpy complexes 4) or lesser extent, with (Pt-Cd) charge transfer (MM'CT). In glassy state (2-MeTHF, 77 K), complexes 1b-4b exhibit structured emissions mainly ascribed to (diimine 1b-3b, trpy 4b) (3)pi pi phosphorescence, likely mixed with some ligand (alkyne) to ligand (imine) charge transfer ((3)LL'CT). Complexes 6 are not emissive in solid state at room temperature. At 77 K they display a high energy (3

  20. Orbital Configuration of the Valence Electrons, Ligand Field Symmetry, and Manganese Oxidation States of the Photosynthetic Water Oxidizing Complex: Analysis of the S(2) State Multiline EPR Signals.

    Science.gov (United States)

    Zheng, Ming; Dismukes, G. Charles

    1996-05-22

    state is caused by change in the intermanganese exchange coupling, without appreciable change in the intrinsic hyperfine tensors. The lack of good simulations of the Ca(2+)-depleted MLS suggests that Ca(2+)-depletion changes both Mn ligation and intermanganese exchange coupling. The 3Mn(IV)-1Mn(III) oxidation model is disfavored because only approximate simulations could be found for the native MLS and no agreement with the NH(3)-bound MLS was obtained. The scalar part of the hyperfine tensors for both Mn(III) and Mn(IV) ions were found to approximate (+/-5%) the values for the dimanganese(III,IV) catalase enzyme, suggesting similar overall ligand types. However, the large (30%) anisotropic part of the Mn(III) hyperfine interaction is opposite in sign to that found in all tetragonally extended six-coordinate Mn(III) ions (i.e., the usual Jahn-Teller splitting). The distribution of spin density from the high-spin d(4) electron configuration of each Mn(III) ion corresponds to a flattened (oblate) ellipsoid. This electronic distribution is favored in five-coordinate ligand fields having trigonally compressed bipyramidal geometry, but it could also arise, in principle, in strained six-coordinate ligand fields having tetragonally compressed geometry, i.e. [Mn(2)(&mgr;-O)](4+) (reverse Jahn-Teller distortion). The resulting valence electronic configurations are described as e'(2)e"(2) and (d(pi))(3)(d(x)()()2(-)(y)()()2)(1), respectively, in contrast to the (d(pi))(3)(d(z)()()2)(1) configuration common to unstrained six-coordinate tetragonally-extended Mn(III) ions, such as found in the [Mn(2)(&mgr;-O)(2)](3+) core in several synthetic dimers and catalase. Both of the former geometries predict strongly oxidizing Mn(III) ions, thereby suggesting a structural basis for the oxidative reactivity of the Mn(4) cluster in the WOC. The magnetic model needed to explain the MLS is not readily reconciled with the simplest structural and electronic models deduced from EXAFS studies of

  1. Gene : CBRC-BTAU-01-2416 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available ographic Model Of Lumirhodopsin pdb|2I35|A Chain A, Crystal Structure Of Rhombohedral Crystal Form Of Ground- State... Rhodopsin pdb|2I36|A Chain A, Crystal Structure Of Trigonal Crystal Form Of Ground-State Rhodopsin p...db|2I36|B Chain B, Crystal Structure Of Trigonal Crystal Form Of Ground-State Rho...dopsin pdb|2I36|C Chain C, Crystal Structure Of Trigonal Crystal Form Of Ground-State Rhodopsin pdb|2I37|A C

  2. Skype-hyped ja Eesti IT-sektori väljakutsed

    Index Scriptorium Estoniae

    2006-01-01

    Eesti IT-sektori potentsiaali ja tulevikuväljavaadete üle arutlevad Martinson Trigon Venture Partners partner Allan Martinson, Helmese juht Jaan Pillesaar, Skype Eesti juht Sten Tamkivi ja EMT tehnoloogia- ja arendusjuht Tõnu Grünberg

  3. Role of Lanthanide-Ligand bonding in the magnetization relaxation ...

    Indian Academy of Sciences (India)

    Ligand bonding. Our calculations transpire comparatively improved Single-Ion Magnet (SIM) behaviour for carbene analogues due to the more axially compressed trigonal prismatic ligand environment. Furthermore, our detailed Mulliken charge, ...

  4. Viisnurga poolitus toodab lisaväärtust / Tarvo Vaarmets

    Index Scriptorium Estoniae

    Vaarmets, Tarvo

    2007-01-01

    Praegusest Viisnurgast saab kinnisvaraarendusettevõte Trigon Property Development ning sellest eraldatakse mööbli ja ehitusmaterjalide tootmine, mis koondatakse uue ettevõtte alla, mille nimeks saab Viisnurk. Vt. samas: Viisnurk. Diagramm: Viisnurga aktsia hind

  5. "Budjem nazhimat" / Allan Martinson ; interv. Petr Birger

    Index Scriptorium Estoniae

    Martinson, Allan, 1966-

    2006-01-01

    Allan Martinson oma asutatud infotehnoloogia ettevõtetest Eestis ja Baltimaades, investeerimisfirma Martinson Trigon Venture Partners investeeringust Vene tarkvarafirmasse Reksoft ning Eesti IT arengust tervikuna. Vt. samas intervjuud Reksoft'i peadirektori Aleksandr Jegoroviga

  6. Allan Martinson - Eesti mees maailmas / Monica Raud

    Index Scriptorium Estoniae

    Raud, Monica, 1981-

    2008-01-01

    Investeerimisfirma Martinson Trigon Venture Partners juhist Allan Martinsonist, tema karjäärist, elulaadist ja harrastustest. Kommenteerivad AS Delfi nõukogu esimees Ville Jehe ja AS Helmes nõukogu esimees Jaan Pillesaar

  7. Acinic Cell Carcinoma in Minor Salivary Glands of Retromolar

    OpenAIRE

    KOYUNCU, Mehmet; Atmaca, Sinan; Bedri KANDEMİR; ÇAKIL, Bünyamin

    2009-01-01

    Acinic cell carcinoma (ACC) is a rare malignant tumor of the salivary glands. ACC of the minor salivary glands is very rare. In the oral cavity, minor salivary gland tumors are rarely seen in the inferior anatomic regions like the retromolar trigone and the floor of mouth compared to the superior regions like the palate. We present a retromolar trigone ACC, a rare location in the oral cavity and discuss the relevant reports in the literature. Key words: Acinic cell carcinoma, minor salivar...

  8. Page 1 2. s ---E. S. f 5 The influence of Cut on Fe-Zn and Ni-Zn ...

    Indian Academy of Sciences (India)

    of 10,000 cm, H, is due to exchange and is of the order of 100 cm, H. is the spin orbit contribution and is of the order of 20 cm and H is due to trigonal field and is equal to 4 cm (Bates and Steggles 1975). We thus find that in magneti- cally ordered system the effect of exchange dominates over the spin orbit and trigonal.

  9. Hydrodistention of the bladder for the treatment of bladder pain syndrome/interstitial cystitis (BPS/IC).

    Science.gov (United States)

    Hoke, Tanya P; Goldstein, Howard; Saks, Emily K; Vakili, Babak

    2017-03-01

    The purpose of this study is to determine whether a transvaginal trigonal block immediately preceding cystoscopy with hydrodistention yields an additional therapeutic benefit compared to cystoscopy with hydrodistention alone for the treatment of bladder pain syndrome/interstitial cystitis (BPS/IC). A retrospective chart review was performed at a single-center. Performance of a trigonal block prior to hydrodistention was at the discretion of the surgeon. A trigonal block consists of injecting 0.25% bupivacaine with 1.0% Xylocaine into the anterior vagina under the trigone under cystoscopic guidance. Procedures between January 1, 2008 and December 31, 2013 were included. The primary outcome compared change in pain score from the baseline to 1-month post-operative. One hundred and eighty-three patients underwent hydrodistention of the bladder. Seventy-seven were excluded and of the 106 patients remaining, 48 received a trigonal block and 58 did not. Both groups had a significant improvement in pain scores (P 5 min based on surgeon preference. There was no difference in change in pain score from baseline between both groups (-3.0 vs. -2.2; P = 0.061). Hydrodistention of the bladder decreased pain postoperatively regardless of trigonal block or time of distention. A randomized-controlled trial is necessary to determine the benefits of duration of hydrodistention or performance of a block. Neurourol. Urodynam. 36:784-786, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Characterization of Bacillus thuringiensis strains from Jordan and ...

    African Journals Online (AJOL)

    Eight serotypes with Bacillus thuringiensis israelensis being the most common. Out of the twenty-six isolated strains, five strains (serotype: kenyae, kurstaki, kurstaki HD1 and thuringiensis) that produced bipyramid crystal proteins were toxic to the lepidoptera larvae of Ephestia kuehniella Zeller. The SDS-PAGE protein ...

  11. Ecology and diversity of Bacillus thuringiensis in soil environment ...

    African Journals Online (AJOL)

    Bacillus thuringiensis populations ranged between 4.23 x 105, 6.52 x 105 cfu/g soil and consist of 11 types of isolates with 3 polymorphic, 7 spherical and 1 bipyramidal type of crystals. Polymorphic crystal containing isolates were further characterized. B. thuringiensis isolates were circular, white, flat and undulate or entire.

  12. SOME SULFATO ADDUCTS AND DERIVATIVE: SYNTHESIS AND SPECTROSCOPIC STUDY

    Directory of Open Access Journals (Sweden)

    MOUHAMADOU BIRAME DIOP

    2014-11-01

    Full Text Available Three new adducts and derivative have been synthesized and studied by infrared and NMR spectroscopies. The suggested structures are discrete with a sulfate behaving as a monochelating, bichelating or monodentate ligand, the environments around the tin centre being octahedral or pentagonal bipyramidal. In all the studied compounds, proposed supramolecular architectures may be obtained when intermolecular hydrogen bonds are considered.

  13. Ferroelectric displacements in multiferroic Y(Mn,Ga)O-3

    NARCIS (Netherlands)

    Adem, U.; Nugroho, A. A.; Meetsma, A.; Palstra, T. T. M.

    We have studied the effects of substitution of Mn3+ by Ga3+ on the crystal structure of YMnO3. Y(Mn,Ga)O-3 is a magnetoferroelectric in which the ferroelectric displacements from the YO7 polyhedra are associated with buckling and tilting of the MnO5 bipyramids. The differences in ionic radius and

  14. Synthesis and structure of bis (-dibenzoyl methanato-O, O′)(aquo ...

    Indian Academy of Sciences (India)

    The compound [UO2(C6H5COCHCOC6H5)2.H2O] was synthesized and characterized by IR, 1H NMR and CHN analysis. Structure of the compound shows that the uranium atom is surrounded by seven oxygen atoms in a pentagonal bi-pyramidal geometry. The water molecule is hydrogen bonded to another molecule via ...

  15. Significance of Charcot Leyden crystals in hepatic aspirates

    Directory of Open Access Journals (Sweden)

    Misra Vatsala

    2009-01-01

    Full Text Available Charcot Leyden crystals are hexagonal bipyramidal structures localised in the primary granules of the cytoplasm of eosinophils and basophils. Their presence, along with eosinophilic infiltrate, is an indirect evidence of parasitic infestation particularly with Toxocara, Capilliriasis, Ascariasis, or Fasciola. We report here two cases where Charcot Leyden crystals with eosinophilic infiltrate were found in the smears prepared from hepatic abscess.

  16. Significance of Charcot Leyden crystals in hepatic aspirates

    OpenAIRE

    Misra Vatsala; Debnath Sharmistha; Misra Sri; Singh Premala

    2009-01-01

    Charcot Leyden crystals are hexagonal bipyramidal structures localised in the primary granules of the cytoplasm of eosinophils and basophils. Their presence, along with eosinophilic infiltrate, is an indirect evidence of parasitic infestation particularly with Toxocara, Capilliriasis, Ascariasis, or Fasciola. We report here two cases where Charcot Leyden crystals with eosinophilic infiltrate were found in the smears prepared from hepatic abscess.

  17. Diaquabis(ethylenediamine-κ2N,N′)copper(II) bis(sulfamerazinate)

    National Research Council Canada - National Science Library

    Direm, Amani; Falek, Wahiba; Pilet, Guillaume; Benali-Cherif, Nourredine

    2014-01-01

    .... The CuII cation shows a strong Jahn–Teller distortion. It is coordinated by four N atoms of two ethylenediamine ligands in the basal plane and two O atoms at much longer distances in the axial positions in a bipyramidal coordination...

  18. Comparison of the Properties of SnCl(3)(-) and SnBr(3)(-) Complexes of Platinum(II).

    Science.gov (United States)

    Nelson, John H.; Wilson, William L.; Cary, Lewis W.; Alcock, Nathaniel W.; Clase, Howard J.; Jas, Gouri S.; Ramsey-Tassin, Lori; Kenney, John W.

    1996-02-14

    The complexes M(3)[Pt(SnX(3))(5)] (M = Bu(4)N(+), PhCH(2)PPh(3)(+); X = Cl, Br), cis-M(2)[PtX(2)(SnX(3))(2)] (M = Bu(4)N(+), PhCH(2)PPh(3)(+), CH(3)PPh(3)(+), Pr(4)N(+); X = Cl, Br), and [PhCH(2)PPh(3)](2)[PtBr(3)(SnBr(3))] have been prepared and characterized by (119)Sn and (195)Pt NMR, far-infrared, and electronic absorption and emission spectroscopies. In acetone solutions the [Pt(SnX(3))(5)](3)(-) ions retain their trigonal bipyramidal structures but are stereochemically nonrigid as evidenced by (119)Sn and (195)Pt NMR spectroscopy. For [Pt(SnCl(3))(5)](3)(-) spin correlation is preserved between 183 and 363 K establishing that the nonrigidity is due to intramolecular tin site exchange, probably via Berry pseudorotation. Whereas, [Pt(SnCl(3))(5)](3)(-) does not undergo loss of SnCl(3)(-) or SnCl(2) to form either [Pt(SnCl(3))(4)](2)(-) or [PtCl(2)(SnCl(3))(2)](2)(-), [Pt(SnBr(3))(5)](3)(-) is not stable in acetone solution in the absence of excess SnBr(2) and forms [PtBr(2)(SnBr(3))(2)](2)(-) and [PtBr(3)(SnBr(3))](2)(-) by loss of SnBr(2). Similarly, [PtCl(2)(SnCl(3))(2)](2)(-) is stable in acetone at ambient temperatures but disproportionates at elevated temperatures and [PtBr(2)(SnBr(3))(2)](2)(-) loses SnBr(2) in acetone to form [PtBr(3)(SnBr(3))](2)(-). The crystal structures of methyltriphenylphosphonium cis-dibromobis(tribromostannyl)platinate(II) and benzyltriphenylphosphonium tribromo(tribromostannyl)platinate(II) have been determined. Both compounds crystallize in the triclinic space group P&onemacr; in unit cells with a = 12.293(16) Å, b = 12.868(6) Å, c = 25.047(8) Å, alpha = 96.11(3) degrees, beta = 91.06(3) degrees, gamma = 116.53(3) degrees, rho(calc) = 2.30 g cm(-)(3), Z = 3 and with a = 11.046(7) Å, b = 14.164(9) Å, c = 22.549(10) Å, alpha = 89.44(4) degrees, beta = 83.32(5) degrees, gamma = 68.31(5) degrees, rho(calc) = 1.893 g cm(-)(3), Z = 2, respectively. Least-squares refinements converged at R = 0.057 and 0.099 for 4048 and 4666

  19. Activation of chalcogens and chalcogenides at reactive uranium centers

    Energy Technology Data Exchange (ETDEWEB)

    Franke, Michael Sebastian

    2015-07-23

    species, react with N{sub 2}O to form a U(V) complex with a terminal oxo ligand. The molecular structure of this compound features two crystallographically independent molecules within the unit cell, one exhibiting trigonal-bipyramidal geometry and one revealing a square-pyramidal coordination environment around the uranium center.

  20. The first dinitrile frameworks of the rare earth elements: infinity(3)[LnCl3(1,4-Ph(CN)2)] and infinity(3)[Ln2Cl6(1,4-Ph(CN)2)], Ln = Sm, Gd, Tb, Y; access to novel metal-organic frameworks by solvent free synthesis in molten 1,4-benzodinitrile.

    Science.gov (United States)

    Höller, Christoph J; Müller-Buschbaum, Klaus

    2008-11-03

    The three-dimensional frameworks infinity(3)[LnCl3(1,4-Ph(CN)2)] of the lanthanides Ln = Sm (1), Gd (2), Tb (3), and infinity(3)[Ln2Cl6(1,4-Ph(CN)2)] for the group 3 metal Y (4) were obtained as single crystalline materials by the reaction of the anhydrous chlorides of the referring rare earth elements with a melt of 1,4-benzodinitrile. No additional solvents were used for the reactions. The dinitrile ligand is strongly coordinating and substitutes parts of the chlorine coordination. The Ln halide structures are reduced to two-dimensional networks, whereas coordination of both nitrile functions to the metal ions renders bridging in the third direction accessible. This enables formation of new metal organic framework (MOF) structure types with the large 1,4-benzodinitrile spacers interlinking infinity (2)[LnCl3] planes. In comparison to 1,4-Ph(CN)2 the mono functional benzonitrile ligand does not constitute framework structures, which is underlined by comparison with a reaction of yttrium chloride with PhCN resulting in the molecular complex [Y2Cl6(PhCN)6] (5) with end-on coordination PhCN ligands. The coordination spheres of the rare earth ions consist of double capped (infinity(3)[LnCl3(1,4-Ph(CN)2)] (1-3)) as well as single capped trigonal prisms (infinity(3)[Ln2Cl6(1,4-Ph(CN)2)] (4)) of chloride ions and N[triple bond]C groups while 5 displays edge sharing pentagonal bipyramids as coordination polyhedra. Sm (1), Gd (2), and Tb (3) exhibit isotypic framework structures with intercrossing dinitrile ligands. The group 3 metal Y (4) gives a framework with a coplanar arrangement of ligands and a lower ligand content. The largest cavities within the MOF structures of 1-4 have diameters of 3.9-8.0 A. All compounds were identified by single crystal X-ray analysis. Mid IR, Far IR, and Raman spectroscopy, microanalyses and simultaneous Differential Thermal Analysis-Thermogravimetry (DTA/TG) were also carried out to characterize the products. Crystal data for infinity(3

  1. A STRONG SECURITY PROTOCOL AGAINST FINGERPRINT DATABASE ATTACKS

    Directory of Open Access Journals (Sweden)

    U. Latha

    2013-08-01

    Full Text Available The Biometric data is subject to on-going changes and create a crucial problem in fingerprint database. To deal with this, a security protocol is proposed to protect the finger prints information from the prohibited users. Here, a security protocol is proposed to protect the finger prints information. The proposed system comprised of three phases namely, fingerprint reconstruction, feature extraction and development of trigon based security protocol. In fingerprint reconstruction, the different crack variance level finger prints images are reconstructed by the M-band Dual Tree Complex Wavelet Transform (DTCWT. After that features are extracted by binarization. A set of finger print images are utilized to evaluate the performance of security protocol and the result from this process guarantees the healthiness of the proposed trigon based security protocol. The implementation results show the effectiveness of proposed trigon based security protocol in protecting the finger print information and the achieved improvement in image reconstruction and the security process.

  2. Ab initio quantum chemical investigation of arsenic sulfide molecular diversity from As4S6 and As4

    Science.gov (United States)

    Kyono, Atsushi

    2013-10-01

    The structural diversity of arsenic sulfide molecules in compositions between As4S6 and As4 was investigated using ab initio quantum chemical calculations. The As4S6 molecule consists of four trigonal pyramid coordinations of As atoms bonding to three S atoms. In the As4S5 composition, only one type of molecular configuration corresponds to an uzonite-type molecule. In the As4S4 composition, two molecular configurations exist with realgar-type and pararealgar-type molecules. Three molecular configurations are in the As4S3 composition. The first configuration comprises trigonal pyramidal As atom coordinations of two types: bonding to two S atoms and one As atom, and bonding to one S atom and two As atoms. The second is the molecular configuration of dimorphite. The third comprises trigonal pyramidal As atom coordinations of two types: bonding to three As atoms, and bonding to one As atom and two S atoms. The As4S2 composition allows molecular configurations of two types. One is comprised of trigonal pyramidal As atom configurations of one type bonding to two As atoms and one S atom. The other comprises trigonal pyramidal As atom coordinations of three types: bonding to two S atoms and one As atoms, bonding to one S atom and two As atoms, and bonding to three As atoms. The As4S molecule has trigonal pyramidal As atom coordinations of two types: bonding to one S atom and two As atoms, and bonding to three As atoms. The As4S composition permits only one molecular configuration, which suggests that the mineral duranusite comprises the As4S molecular geometry. In all, ten molecular configurations are predicted in the molecular hierarchy of the arsenic sulfide binary system. The simulated Raman spectral profiles are helpful in searching for undiscovered arsenic sulfide minerals.

  3. NCBI nr-aa BLAST: CBRC-MEUG-01-2279 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available ecName: Full=Rhodopsin pdb|1JFP|A Chain A, Structure Of Bovine Rhodopsin (Dark Adapted) pdb|1LN6|A Chain A, Structure... Of Bovine Rhodopsin (Metarhodopsin Ii) pdb|1GZM|A Chain A, Structure Of Bovine Rhodopsin In A Trig...onal Crystal Form pdb|1GZM|B Chain B, Structure Of Bovine Rhodopsin In A Trigonal... Crystal Form pdb|1HZX|A Chain A, Crystal Structure Of Bovine Rhodopsin pdb|1HZX|B Chain B, Crystal Structure... Of Bovine Rhodopsin pdb|1L9H|A Chain A, Crystal Structure Of Bovine Rhodopsin At 2.6 Angstroms Resolution

  4. The unique rht-MOF platform, ideal for pinpointing the functionalization and CO 2 adsorption relationship

    KAUST Repository

    Luebke, Ryan

    2012-01-01

    The uniqueness of the rht-MOF platform, based on the singular (3,24)-connected net, allows for the facile design and synthesis of functionalized materials for desired applications. Here we designed a nitrogen-rich trefoil hexacarboxylate (trigonal tri-isophthalate) ligand, which serves to act as the trigonal molecular building block while concurrently coding the formation of the targeted truncated cuboctahedral supermolecular building block (in situ), and enhancing the CO 2 uptake in the resultant rht-MOF. © 2012 The Royal Society of Chemistry.

  5. Bis(μ-2-methylquinolin-8-olato-κ3N,O:O;κ3O:N,O-bis[(acetato-κO(methanol-κOzinc(II

    Directory of Open Access Journals (Sweden)

    Seik Weng Ng

    2009-05-01

    Full Text Available The reaction of zinc acetate and 2-methyl-8-hydroxyquinoline in methanol yielded the centrosymmetric dinuclear title compound, [Zn2(C10H8NO2(CH3CO22(CH3OH2], which has the Zn atom within a distorted NO4 trigonal–bipyramidal coordination geometry. Methanol–acetate O—H...O hydrogen bonds link the dinculear units into a linear supramolecular chain extending parallel to [100].

  6. Hydrothermal syntheses and characterization of uranyl tungstates with electro-neutral structural units

    Energy Technology Data Exchange (ETDEWEB)

    Balboni, Enrica; Burns, Peter C. [Univ. of Notre Dame, IN (United States). Dept. of Civil and Enviromental Engineering and Earth Sciences; Univ. of Notre Dame, IN (United States). Dept. of Chemistry and Biochemistry

    2015-11-01

    Two uranyl tungstates, (UO{sub 2})(W{sub 2}O{sub 7})(H{sub 2}O){sub 3} (1) and (UO{sub 2}){sub 3}(W{sub 2}O{sub 8})F{sub 2}(H{sub 2}O){sub 3} (2), were synthesized under hydrothermal conditions at 220 C and were structurally, chemically, and spectroscopically characterized. 1 Crystallizes in space group Pbcm, a = 6.673(5) Aa, b = 12.601(11) Aa, c = 11.552 Aa; 2 is in C2/m, a = 13.648(1) Aa, b = 16.852(1) Aa, c = 9.832(1) Aa, β = 125.980(1) {sup circle}. In 1 the U(VI) cations are present as (UO{sub 2}){sup 2+} uranyl ions that are coordinated by five oxygen atoms to give pentagonal bipyramids. These share two edges with two tungstate octahedra and single vertices with four additional octahedra, resulting in a sheet with the iriginite-type anion topology. Only water molecules are located in the interlayer. The structural units of 2 consist of (UO{sub 2}){sup 2+} uranyl oxy-fluoride pentagonal bipyramids present as either [UO{sub 2}F{sub 2}O{sub 3}]{sup -6} or [UO{sub 2}FO{sub 4}]{sup -5}, and strongly distorted tungstate octahedra. The linkage of uranyl pentagonal bipyramids and tungstate octahedra gives a unique sheet anion topology consisting of pentagons, squares and triangles. In 2, the uranyl tungstates sheets are connected into a novel electro-neutral three-dimensional framework through dimers of uranyl pentagonal bipyramids. These dimers connecting the sheets share an edge defined by F anions. 2 is the first example of a uranyl tungstate oxy-fluoride, and 1 and 2 are rare examples of uranyl compounds containing electro-neutral structural units.

  7. catena-Poly[[trimethyltin(IV]-μ-1,2,3-benzotriazol-1-ido-κ2N1:N3

    Directory of Open Access Journals (Sweden)

    Yuanyuan Li

    2012-02-01

    Full Text Available In the title coordination polymer, [Sn(CH33(C6H4N3]n, the SnIV atom is five-coordinated in a distorted trigonal–bipyramidal geometry with the methyl groups in equatorial positions and two N atoms of two symmetry-related benzotriazolide anions in axial positions. The anion bridges adjacent metal atoms, forming zigzag polymeric chains parallel to [011] and [0-11].

  8. Shape Separation of Colloidal Metal Nanoparticles via Size Exclusion Chromatography

    OpenAIRE

    Marvi, Sarrah

    2016-01-01

    The inherent polydispersity of solution-based, colloidal nanoparticle syntheses has necessitated the development of facile post-processing methods for the purification of anisotropic nanoparticles. Here, the use of size exclusion chromatography is explored for the shape separation of colloidal silver nanocube and colloidal gold bipyramid solutions. Multiple column packing materials, pore sizes, and mobile phases were tested to address the prevalent issues of metal adsorption to the high surfa...

  9. (Cy2NH2O2CPh3(SnCl42 AND (SnBu24(O2CPh16Cl6(OH2(Cy2NH216: SYNTHESIS AND SPECTROSCOPIC CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    Dinora De Barros

    2011-09-01

    Full Text Available The two title compounds have been synthesized, their IR and Mössbauer studies carried out. The structures are discrete and contain mono- and bidentate PhCO2-, the environment around the tin (IV centre being octahedral (in SnCl4 adduct, trapezoidal bipyramidal (in the SnBu2 residue containing derivative. A tetranuclear monomeric or an oligomeric structure is suggested in the tetranuclear SnBu2 residue containing derivative.

  10. Synthesis, structure, and spectroscopic characterization of three uranyl phosphates with unique structural units

    Science.gov (United States)

    Wylie, Ernest M.; Dawes, Colleen M.; Burns, Peter C.

    2012-12-01

    Single crystals of Zn4(OH)2[(UO2)(PO4)2(OH)2(H2O)] (UZnP), Cs[(UO2)(HPO4)NO3] (UCsP), and In3[(UO2)2(PO4)4OH(H2O)6].2H2O (UInP) were obtained from hydrothermal reactions and have been structurally and chemically characterized. UZnP crystallizes in space group Pbcn, a=8.8817(7), b=6.6109(5), c=19.569(1) Å; UCsP crystallizes in P-1, a=7.015(2), b=7.441(1), c=9.393(2) Å, α=72.974(2), β=74.261(2), γ=79.498(2); and UInP crystallizes in P-1, a=7.9856(5), b=9.159(1), c=9.2398(6) Å α=101.289(1), β=114.642(1), γ=99.203(2). The U6+ cations are present as (UO2)2+ uranyl ions coordinated by five O atoms to give pentagonal bipyramids. The structural unit in UZnP is a finite cluster containing a uranyl pentagonal bipyramid that shares corners with two phosphate tetrahedra. The structural unit in UCsP is composed of uranyl pentagonal bipyramids with one chelating nitrate group that are linked into chains by three bridging hydrogen phosphate tetrahedra. In UInP, the structural unit contains pairs of edge-sharing uranyl pentagonal bipyramids with two chelating phosphate tetrahedra that are linked into chains through two bridging phosphate tetrahedra. Indium octahedra link these uranyl phosphate chains into a 3-dimensional framework. All three compounds exhibit unique structural units that deviate from the typical layered structures observed in uranyl phosphate solid-state chemistry.

  11. (Acetato-κO{bis[(2,4-dimethyl-1H-pyrazol-1-ylmethyl][(pyridin-2-ylmethyl]amine}cobalt(II hexafluoridophosphate

    Directory of Open Access Journals (Sweden)

    Fan Yu

    2012-10-01

    Full Text Available In the title compound, [Co(CH3CO2(C18H24N6]PF6, the CoII atom is pentacoordinated in a distorted trigonal–bipyramidal geometry by four N atoms from a tripodal ligand and one O atom from a monodentate acetate ligand. The crystal packing is stabilized by intermolecular C—H...F and C—H...O hydrogen bonds.

  12. [(2-Morpholinoethyl(2-pyridylmethyleneamine]dithiocyanatozinc(II

    Directory of Open Access Journals (Sweden)

    Bang-Hong Cai

    2009-02-01

    Full Text Available The title compound, [Zn(NCS2(C12H17N3O], was prepared by the reaction of zinc acetate with pyridine-2-carbaldehyde, 2-morpholinoethylamine and ammonium thiocyanate in an ethanol solution. The ZnII atom is five coordinate with a distorted trigonal–bipyramidal geometry, coordinating with three N atoms of the Schiff base (2-morpholinoethyl(2-pyridylmethylideneamine and two N atoms from two thiocyanate ligands. The morpholine ring adopts a chair configuration.

  13. Thermal expansion and magnetic properties of benzoquinone-bridged dinuclear rare-earth complexes.

    Science.gov (United States)

    Moilanen, Jani O; Mansikkamäki, Akseli; Lahtinen, Manu; Guo, Fu-Sheng; Kalenius, Elina; Layfield, Richard A; Chibotaru, Liviu F

    2017-10-10

    The synthesis and structural characterization of two benzoquinone-bridged dinuclear rare-earth complexes [BQ(MCl2·THF3)2] (BQ = 2,5-bisoxide-1,4-benzoquinone; M = Y (1), Dy (2)) are described. Of these reported metal complexes, the dysprosium analogue 2 is the first discrete bridged dinuclear lanthanide complex in which both metal centres reside in pentagonal bipyramidal environments. Interestingly, both complexes undergo significant thermal expansion upon heating from 120 K to 293 K as illustrated by single-crystal X-ray and powder diffraction experiments. AC magnetic susceptibility measurements reveal that 2 does not show the slow relation of magnetization in zero dc field. The absent of single-molecule behaviour in 2 arises from the rotation of the principal magnetic axis as compared to the pseudo-C5 axis of the pentagonal bipyramidal environment as suggested by ab initio calculations. The cyclic voltammetry and chemical reduction experiments demonstrated that complexes 1 and 2 can be reduced to radical species containing [BQ(3)˙(-)]. This study establishes efficient synthetic strategy to make bridged redox-active multinuclear lanthanide complexes with a pentagonal bipyramidal coordination environment that are potential precursors for single-molecule magnets.

  14. Uranyl peroxide pyrophosphate cage clusters with oxalate and nitrate bridges.

    Science.gov (United States)

    Ling, Jie; Ozga, Michael; Stoffer, Megan; Burns, Peter C

    2012-06-28

    Two complex cage clusters built from uranyl hexagonal bipyramids and multiple types of bridges between uranyl ions, U(30)Py(10)Ox(5) and U(38)Py(10)Nt(4), were crystallized from aqueous solution under ambient conditions. These are built from 30 uranyl hexagonal bipyramids, 10 pyrophosphate groups, and five oxalate bridges in one case, and 38 uranyl hexagonal bipyramids, 10 pyrophosphate groups, and four nitrate groups in the other. The crystal compositions are (H(3)O)(10)Li(18)K(22)[(UO(2))(30)(O(2))(30)(P(2)O(7))(10)(C(2)O(4))(5)](H(2)O)(22) and Li(24)K(36)[(UO(2))(38)(O(2))(40)(OH)(8)(P(2)O(7))(10)(NO(3))(4)](NO(3))(4)(H(2)O)(n) for U(30)Py(10)Ox(5) and U(38)Py(10)Nt(4), respectively. Cluster U(30)Py(10)Ox(5) crystallizes over a narrow range of solution pH that encourages incorporation of both oxalate and pyrophosphate, with incorporation of oxalate only being favored under more acidic conditions, and pyrophosphate only under more alkaline conditions. Cluster U(38)Py(10)Nt(4) contains two identical lobes consisting of uranyl polyhedra and pyrophosphate groups, with these lobes linked into the larger cluster through four nitrate groups. The synthesis conditions appear to have prevented closure of these lobes, and a relatively high nitrate concentration in solution favored formation of the larger cluster.

  15. Diffusion of Helium Isotopes in Silicate Glasses and Minerals: Implications for Petrogenesis and Geochronology.

    Science.gov (United States)

    1989-06-01

    stable form, trigonal alpha-quartz, to a more ordered hexagonal form, hexagonal beta -quartz (Deer, Howie, and Zussman, 1966). However, this conversion...diffusion of helium and neon in tridymite and cristobalite .Trans. Farad. Soc. 63, 2225-2290. BARRETT P.J. (1972) Stratigrapgy and petrology of the

  16. Eesti viimane kolhoos pelgab tulevikku / Anne Oja ; kommenteerinud Vallo Visnapuu, Argo Mättas, Mart Vaiksaar ... [jt.

    Index Scriptorium Estoniae

    Oja, Anne, 1970-

    2011-01-01

    Vändra katsesovhoosi jagunemisel loodud OÜ Selja nõukogu ja juhatus on otsustanud firma maha müüa, kuigi enamik ettevõtte 197-st eraisikust osanikust on selle vastu. Võimalikud ostjad on Trigon Farming AS või Jõgeva Põllumajandustootjate Liit (JPL)

  17. A dysprosium-based metal-organic framework: Synthesis ...

    Indian Academy of Sciences (India)

    ray diffraction study showed a tricapped trigonal prism geometry for lanthanide in the [Dy(pyda)3]3− fragment. The mode of interaction of 1 with calf thymus- DNA and with protein bovine serum albumin (BSA) was investigated by using absorption ...

  18. Anisotropy in elastic properties of lithium sodium sulphate ...

    Indian Academy of Sciences (India)

    explained elsewhere (McSkimin 1964; Papadakis 1976). A. MATEC model 7700 Pulse modulator and .... of a crystal. The Young's moduli surface plots are also very important in this regard. The Young's modulus. (Nye 1957; Alex and Philip 2000), E, in the direction of the unit vector, ni , for a trigonal crystal is given by. E.

  19. Fully relativistic coupled cluster and DFT study of electric field gradients at Hg in 199Hg compounds

    DEFF Research Database (Denmark)

    Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.

    2012-01-01

    We investigate the magnitude and interplay of relativistic and electron correlation effects on the electric field gradient (EFG) at the position of Hg in linear and bent HgL2 (L=CH3, Cl, Br, I) and trigonal planar [HgCl3]- complexes using four-component relativistic Dirac-Coulomb (DC) and non...

  20. Synthesis and characterization of monomeric manganese(II) and ...

    African Journals Online (AJOL)

    The geometry at the manganese center is seven-coordinate, and is best described as a capped trigonal pyramid with the water molecule forming the cap and the six nitrogen atoms of the tpen ligand occupying the pyramidal sites. The manganese atom and the water molecule lie on a crystallographic twofold axis.

  1. Trichloridotris{N-[phenyl(pyridin-2-ylmethylidene]hydroxylamine-κ2N,N′}samarium(III

    Directory of Open Access Journals (Sweden)

    Yahong Li

    2012-03-01

    Full Text Available The SmIII ion in the title compound, [SmCl3(C12H10N2O3], shows a coordination number of nine with a slightly distorted tricapped trigonal prismatic geometry based on a Cl3N6 donor set. The molecular structure is stabilized by three intramolecular O—H...Cl hydrogen bonds.

  2. Case of ectopic ureteral orifice with hypoplastic kidney diagnosed by enhanced computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kishi, Mikio; Yoshimoto, Jun; Matsumura, Yosuke; Ohmori, Hiroyuki (Okayama Univ. (Japan). School of Medicine)

    1983-08-01

    A case of ectopic ureteral orifice, 6 year old girl with urinary incontinece, is herein reported. Cystoscopy and excretory urogram showed absence of right half of trigone and non visualizing kidney. By enhanced computed tomography, right hypoplastic kidney was found and right nephrectomy was performed. We emphasize that enhanced computed tomography is very useful for diagnosis of localization of hypoplastic kidney.

  3. Is C-50 a superaromat? Evidence from electronic structure and ring current calculations

    NARCIS (Netherlands)

    Matias, Ana Sanz; Havenith, Remco W. A.; Alcami, Manuel; Ceulemans, Arnout

    2016-01-01

    The fullerene-50 is a 'magic number' cage according to the 2(N + 1)(2) rule. For the three lowest isomers of C-50 with trigonal and pentagonal symmetries, we calculate the sphericity index, the spherical parentage of the occupied p-orbitals, and the current density in an applied magnetic field. The

  4. A rod-packing microporous hydrogen-bonded organic framework for highly selective separation of C2H2/CO2at room temperature

    KAUST Repository

    Li, Peng

    2014-11-13

    Self-assembly of a trigonal building subunit with diaminotriazines (DAT) functional groups leads to a unique rod-packing 3D microporous hydrogen-bonded organic framework (HOF-3). This material shows permanent porosity and demonstrates highly selective separation of C2H2/CO2 at ambient temperature and pressure.

  5. An alkaline tin(II) halide compound Na{sub 3}Sn{sub 2}F{sub 6}Cl: Synthesis, structure, and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Pifu [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Luo, Siyang [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Huang, Qian; Yang, Yi [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Jiang, Xingxing [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Liang, Fei [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Chen, Chuangtian [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Lin, Zheshuai, E-mail: zslin@mail.ipc.ac.cn [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China)

    2017-04-15

    A new alkali tin(II) halide compound, Na{sub 3}Sn{sub 2}F{sub 6}Cl, is synthesized by hydrothermal method. This compound crystallizes trigonally in space group of R-3c (167), and processes a zero-dimensional (0D) structure consisted of Na{sup +} cations, Cl{sup −} anions and the isolated [SnF{sub 3}]{sup -} trigonal pyramids in which the stereochemically active 5s{sup 2} lone pair electrons are attached to the Sn{sup 2+} cations. Interestingly, the [SnF{sub 3}]{sup −} trigonal pyramids are parallel arranged in the a-b plane, while oppositely arranged in line with rotation along the c- axis. Moreover, the energy bandgap, thermal stability and electronic structure of Na{sub 3}Sn{sub 2}F{sub 6}Cl are characterized and the results reveal that this compound has and indirect bandgap of 3.88 eV and is stable under 270 °C. - Graphical abstract: A zero-dimensional alkaline tin halide compound, Na{sub 3}Sn{sub 2}F{sub 6}Cl, is synthesized by hydrothermal method. Interestingly, both the anions and cations coordinating polyhedra exhibit order arranged with the [SnF{sub 3}]{sup -} trigonal pyramids rotating along the c- axis.

  6. Calicovesicostomy for ureteropelvic junction obstruction in a solitary ...

    African Journals Online (AJOL)

    trigone and left ureteric orifice. Right RGP showed UPJO with high insertion of ureter. A diagnosis of a right solitary ecto- pic kidney with UPJO and high insertion of ureter was confirmed. The patient was placed supine with the right side slightly.

  7. The sonographic visualization of the vesico-ureteral junction.

    Science.gov (United States)

    Marchal, G J; van Dijck, X M; Kint, E J; Peeters, S R; Baert, A L; Goddeeris, P

    1982-06-01

    The anatomical relationship between the terminal ureter, the trigone and the vesico-ureteral junction was studied in vivo by ultrasound. In healthy test persons successful visualization and differentiation of the submucosal, transmural and retrovesical segments of the terminal ureter could be obtained. Some potential clinical applications of the method are discussed.

  8. Trigonalgia: An overlooked cause of bladder pain | Aminu | African ...

    African Journals Online (AJOL)

    Bladder pain is a cause of chronic pelvic pain, which constitutes a common presentation in urology outpatient consultation, especially among females. Some endoscopic features of the trigone observed during cystoscopy was correlated with mild to moderately bothersome bladder pain, termed trigonalgia. This is due to ...

  9. Detrusor wall thickness compared to other non-invasive methods in ...

    African Journals Online (AJOL)

    W. ElSaied

    noninvasive, tools, using pressure flow studies as a reference, in the assessment of bladder outlet, obstruction among men presenting with ... frequently rely on less invasive methods (such as urinary flow rate, post-void residual [PVR], and ... wall,dome and whenever possible right and left lateral walls and trigone, taking the ...

  10. Relativistic Band Structure and Fermi Surface of PdTe2 by the LMTO Method

    DEFF Research Database (Denmark)

    Jan, J. P.; Skriver, Hans Lomholt

    1977-01-01

    The energy bands of the trigonal layer compound PdTe2 have been calculated, using the relativistic linear muffin-tin orbitals method. The bandstructure is separated into three distinct regions with low-lying Te 5s bands, conduction bands formed by Pd 4d and Te 5p states, and high-lying bands formed...

  11. (Diethyl ether{1-[2-(1-methyl-1H-imidazol-2-yl-κN3-1,1-diphenylethyl]-(1,2,3,3a,7a-η-indenyl}lithium(I

    Directory of Open Access Journals (Sweden)

    Maxim V. Borzov

    2009-05-01

    Full Text Available In the title compound, [Li(C27H23N2(C4H10O], the Li atom possesses a nearly planar trigonal coordination environment (assuming the cyclopentadienyl ring of the indenyl group occupies one coordination place. The diethyl ether ligand adopts a nearly planar W-type conformation.

  12. Norma ja Eesti Telekomi ootused vastuolulised / Annika Matson

    Index Scriptorium Estoniae

    Matson, Annika, 1976-

    2003-01-01

    16.-17. juulil 2003 avalikustavad Eesti Telekom ja Norma oma teise kvartali tulemused. Kõik majandusanalüütikud ennustavad firmadele korralikku kasumit, kuid ootused kõiguvad 25 protsendi ulatuses. Diagramm: Eesti Telekomilt ootab suurimat kasumit Trigon, Normalt Hansapank

  13. Eestlased rahastavad Venemaa arvutimänguäri / Toivo Tänavsuu

    Index Scriptorium Estoniae

    Tänavsuu, Toivo

    2008-01-01

    Allan Martinsonile ja Joakim Heleniusele kuuluv riskikapitalifond MartinsonTrigon investeeris koos partneritega Venemaa suurimasse arvutimängude tootja- ja levifirmasse Novõi Disk 200 miljonit krooni, Skype'i endine juhtinsener Toivo Annus paigutas kaks miljonit dollarit Singapuri tarkvarafirmasse Garena

  14. Ruthenium-based four-coordinate olefin metathesis catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Sanford, M.S.; Henling, L.M.; Day, M.W.; Grubbs, R.H. [California Inst. of Tech., Pasadena (United States). Div. of Chemistry and Chemical Engineering

    2000-10-02

    A series of four-coordinate Ru{sup II} alkylidenes has been prepared as analogues of the proposed olefin metathesis intermediate [(PCy{sub 3})Cl{sub 2}Ru=CHPh]. These complexes exhibit unusual trigonal-pyramidal solid-state geometries, and are rendered highly active for ring-closing metathesis by the addition of HCl. (orig.)

  15. Combined Vesicovaginal and Rectovaginal Fistulas Associated with ...

    African Journals Online (AJOL)

    the history is obtained after discovery of the fistula2. Fewer than ten case reports in the ... the bladder into the vagina and the rectum. Cystoscopy under anesthesia revealed a vesicovaginal fistula above the trigone, 3 cm in diameter, and the presence of a hard, blue, calcified mass. Pelvic examination under anesthesia.

  16. X-Ray structural investigation of VAS-393 crystals

    CERN Document Server

    Martirosian, A H; Harurtjunian, V S

    2001-01-01

    X-ray structural study of VAS-393 crystals was performed. Investigations were carried out with the use of the Weissenberg rotating and powder (employing the Bjornstrem diagrams) methods. The lattice constants ''c'' and ''a''are calculated. The crystal is shown to belong to the trigonal syngony (medium category)

  17. On a conjecture on linear systems

    Indian Academy of Sciences (India)

    Abstract. In a remark to Green's conjecture, Paranjape and Ramanan analysed the vector bundle E which is the pullback by the canonical map of the universal quotient bundle TPg−1(−1) on Pg−1 and stated a more general conjecture and proved it for the curves with Clifford Index 1 (trigonal and plane quintics). In this paper ...

  18. Towards accurate structural characterization of metal centres in protein crystals: the structures of Ni and Cu T6 bovine insulin derivatives

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl; Mossin, Susanne; Ståhl, Kenny

    2014-01-01

    of the copper insulin derivative was deteriorated as a consequence of radiation damage. To provide more detail, X-ray absorption spectroscopy (XAS) was used to improve the information level about metal coordination in each derivative. The nickel derivative contains hexacoordinated Ni2+ with trigonal symmetry...

  19. Endoscopic Resection of a Prominent Median Lobe During TURP: a ...

    African Journals Online (AJOL)

    Endoscopic Resection of a Prominent Median Lobe During TURP: a Simple Technique to Avoid Sub- Trigonal Resection. AA Attia, MTA Al-Hak. Abstract. No Abstract. Key Words: Benign prostatic hyperplasia, surgery, Transurethral resection of prostate, Endoscopic resection, prominent median lobe. Full Text: EMAIL FREE ...

  20. African Journal of Urology - Vol 16, No 3 (2010)

    African Journals Online (AJOL)

    Endoscopic Resection of a Prominent Median Lobe During TURP: a Simple Technique to Avoid Sub- Trigonal Resection · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. AA Attia, MTA Al-Hak. http://dx.doi.org/10.1007/s12301-010-0020-9 ...

  1. Influence of Ge content on the optical properties of X and W centers in dilute Si-Ge alloys

    DEFF Research Database (Denmark)

    Leitão, J.P.; Carvalho, A.; Marques Pereira, Rui Nuno

    2011-01-01

    Photoluminescence (PL) measurements, performed in Si and Si1−xGex alloys (x= 0.0069 and 0.0125) irradiated with protons and annealed between 100 and 650 ∘C, are combined with first-principles calculations to assess the assignment of the W and X lines to the trigonal and tetragonal forms of the tri...

  2. Purification, crystallization and preliminary X-ray structure analysis of the banana lectin from Musa paradisiaca.

    Science.gov (United States)

    Singh, D D; Saikrishnan, K; Kumar, Prashant; Dauter, Z; Sekar, K; Surolia, A; Vijayan, M

    2004-11-01

    The banana lectin from Musa paradisiaca, MW 29.4 kDa, has been isolated, purified and crystallized. The trigonal crystals contain one dimeric molecule in the asymmetric unit. The structure has been solved using molecular replacement to a resolution of 3 A. The structure of the subunit is similar to that of jacalin-like lectins.

  3. Computers and Mathematics

    Science.gov (United States)

    1989-01-01

    of Hopf Bifurcation E. Freire , E. Garnero, E. Ponce, University of Sevilla, Spain ............................ 109 Application of the Reduce Computer...L. Finkelstein.................... 27 D. Rockrnore .................... 156 E. Freire ........................ 109 C. J1. Roehrig...Uni- versity, 1985. 59 Classicality of Trigonal Curves of Genus Five Paulo Viana 1 M.I.T. Massachussets Institute of Technology and P.U.C. Pontificia

  4. STRUCTURAL AND DYNAMIC PROPERTIES OF SOLID-SOLUTIONS OF BAF2 AND GDF3 - AN EPR STUDY

    NARCIS (Netherlands)

    DENHARTOG, HW

    Results of EPR experiments on solid solutions of barium and gadolinium fluoride in the temperature range 300 to 900 K are presented. At room temperature the Gd-ions are located predominantly at trigonal sites. If the temperature is increased, the interstitial fluoride ions are found to dissociate

  5. On a conjecture on linear systems

    Indian Academy of Sciences (India)

    In a remark to Green's conjecture, Paranjape and Ramanan analysed the vector bundle E which is the pullback by the canonical map of the universal quotient bundle T P g − 1 ( − 1 ) on P g − 1 and stated a more general conjecture and proved it for the curveswith Clifford Index 1 (trigonal and plane quintics). In this paper ...

  6. Vene mõjukaim IT-guru soovitab Eesti uuendusi ida poole müüa / Henrik Roonemaa

    Index Scriptorium Estoniae

    Roonemaa, Henrik

    2005-01-01

    Eestit külastanud Venemaa mõjukamaid IT-gurusid Alexander Galitsky soovitab Eestis välja töötatud ja toimivaid innovaatilisi lahendusi pakkuda Venemaa turule. Alexander Galitsky nõustab Allan Martinsoni investeerimisfirmat Martinson Trigon Venture Partners. Vt. samas: E-riigi Akadeemia aitab firmade saavutused itta

  7. Theoretical studies of the g factors and local structure for Pt 3 in -Al ...

    Indian Academy of Sciences (India)

    3 are theoretically investigated from the perturbation formulas of the factors for a 57 ion in trigonal symmetry. The Pt3+ impurity is found to experience an outward displacement by about 0.18 Å away from the centre of the oxygen ...

  8. Fondijuhid jäid Heleniuse isule alla / Martin Hanson

    Index Scriptorium Estoniae

    Hanson, Martin, 1984-

    2007-01-01

    Varahaldusosakonna viis võtmetöötajat - juht Kristel Kivinurm-Priisalm, investeeringute juhid Toomas Reisenbuk ja Aadu Oja, fondijuht Valdur Jaht ja finantsjuht Kadri Haldre lahkusid Trigon Capitalist kuna nende tulevikunägemus erines omaniku Joakim Heleniuse omast. Diagrammid: Trigoni fondide näitajad. Vt. samas: Trigoni uus meeskond juba määratud

  9. Theoretical evaluation of the electron paramagnetic resonance spin ...

    Indian Academy of Sciences (India)

    The impurity displacements for Fe3+ and Ru3+ in corundum (Al2O3) are theoretically studied using the perturbation formulas of the spin Hamiltonian parameters (zero-field splitting and anisotropic factors) for a 3d5 (with high spin = 5/2) and a 4d5 (with low spin = 1/2) ion in trigonal symmetry, respectively. According ...

  10. Electron paramagnetic resonance parameters of Mn4+ ion in h ...

    Indian Academy of Sciences (India)

    The EPR parameters ( factors ∥, ⊥ and zero-field splitting ) of Mn4+ ion in h-BaTiO3 crystal are calculated from the complete high-order perturbation formulas based on a two-mechanism model for the EPR parameters of 33 ions in trigonal symmetry. In the model, not only the widely used crystal-field mechanism, ...

  11. High-pressure Al-rich hexagonal phases-What are their kin?

    DEFF Research Database (Denmark)

    Makovicky, Emil; Olsen, Lars Arnskov

    2008-01-01

    The hexagonal Al-rich high-pressure phases are members of a structural family with the same type of framework composed of double-ribbons of edge-sharing octahedra, but variably occupied trigonal and hexagonal channels. This family includes jaffeite, fluoborite, yeremeyevite, painite, and syntheti...... Ba indates. This kinship broadens the spectrum of elements potentially accommodated by these phases in the mantle....

  12. Preliminary X-ray Study of Naproxen Esterase from Bacillus subtilis

    NARCIS (Netherlands)

    van der Laan, Jan; Teplyakov, A.V.; Lammers, A.A.; Dijkstra, B.W.

    1993-01-01

    Single crystals of naproxen esterase from Bacillus subtilis have been obtained from PEG6000 solutions at pH 8.0 by liquid-liquid diffusion while applying a temperature gradient from 4°C to room temperature over a period of four weeks. The crystals belong to the trigonal space group P3121 or P3221

  13. Temperature-dependent analysis of thermal motion, disorder and structures of tris(ethylenediamine)zinc(II)sulfate and tris(ethylenediamine)copper(II) sulfate

    NARCIS (Netherlands)

    Smeets, S.; Parois, P.J.A.; Bürgi, H.-B.; Lutz, M.

    2011-01-01

    The crystal structures of the title compounds have been determined in the temperature range 140–290 K for the zinc complex, and 190–270 K for the copper complex. The two structures are isostructural in the trigonal space group P 331c with the sulfate anion severely disordered on a site with 32 (D3)

  14. Diffraction catastrophes and semiclassical quantum mechanics for Veselago lensing in graphene

    Science.gov (United States)

    Reijnders, K. J. A.; Katsnelson, M. I.

    2017-07-01

    We study the effect of trigonal warping on the focusing of electrons by n-p junctions in graphene. We find that perfect focusing, which was predicted for massless Dirac fermions, is only preserved for one specific lattice orientation. In the general case, trigonal warping leads to the formation of cusp caustics, with a different position of the focus for graphene's two valleys. We develop a semiclassical theory to compute these positions and find very good agreement with tight-binding simulations. Considering the transmission as a function of potential strength, we find that trigonal warping splits the single Dirac peak into two distinct peaks, leading to valley polarization. We obtain the transmission curves from tight-binding simulations and find that they are in very good agreement with the results of a billiard model that incorporates trigonal warping. Furthermore, the positions of the transmission maxima and the scaling of the peak width are accurately predicted by our semiclassical theory. Our semiclassical analysis can easily be carried over to other Dirac materials, which generally have different Fermi surface distortions.

  15. Investeerimisfondide Ferrarid / Margo Kokerov

    Index Scriptorium Estoniae

    Kokerov, Margo, 1978-

    2006-01-01

    Peeter Schamardin varahaldusfirmast Sampo Baltic Asset Management, SEB Ühispanga Fondide juht Sven Kunsing, Hansa Investeerimisfondide fondijuht Alvar Roosimaa, Suprema varahalduse juht Veikko Maripuu ning Trigon Capitali varahalduse juht Kristel Kivinurm-Priisalm investeerimisfondide tootlusest 2006. aastaks. Tabel: Möödunud aasta ralliässad

  16. Hydrogen bonding induced polymorphism in the scandium(III) complex with ε-caprolactam

    Energy Technology Data Exchange (ETDEWEB)

    Virovets, Alexander V.; Peresypkina, Eugenia V. [Institute of Inorganic Chemistry SB RAS, Novosibirsk (Russian Federation); Novosibirsk State Univ. (Russian Federation); Cherkasova, Elizaveta V.; Cherkasova, Tatjana G. [Kuzbass State Technical Univ., Kemerovo (Russian Federation)

    2015-11-01

    Two polymorphs of [Sc(cpl){sub 6}][Cr(NCS){sub 6}] (cpl=ε- C{sub 6}H{sub 11}NO), trigonal and monoclinic, form purple elongated narrow plates and brownish-purple prisms and are formed concomitantly irrespectively of the crystallization conditions. In the trigonal polymorph both cation and anion possess C{sub 3i} site symmetry while in the monoclinic form cation and anion lie on inversion centre and 2-fold axis respectively. The nature of the polymorphism traces back to a redistribution of inter- and intramolecular hydrogen bonds that causes different conformation of the complex cations, different hydrogen bonding and different molecular packings. The [Sc(cpl){sub 6}]{sup 3+} cations in the structure of the trigonal polymorph form intermolecular N(H)..S, and in the monoclinic form both N(H)..S inter- and N(H)..O intramolecular hydrogen bonds with NCS groups of [Cr(NCS){sub 6}]{sup 3-} and cpl ligands. This aggregation leads to chains, where the cations and the anions alternate, in the trigonal modification and to layers, in which each ion is surrounded by four counterions, in the monoclinic form. Both polymorphs possess thermochromic properties, and a reversible color change from light purple to dark green takes place at 470-475 K.

  17. Pressure-induced polymorphism in hypervalent Cs I3

    Science.gov (United States)

    Patel, Nishant N.; Sunder, Meenakshi; Garg, Alka B.; Poswal, H. K.

    2017-11-01

    We report the results of ambient temperature high-pressure synchrotron-based x-ray diffraction, Raman, and electrical resistance study of Cs I3 up to 29, 25, and 8 GPa, respectively, and confirm three-phase transitions under quasihydrostatic conditions. The ambient orthorhombic (space group (SG): Pnma) phase of Cs I3 is stable up to a pressure of ˜1.3 GPa , above which a phase transition to a trigonal (SG : P -3 c 1 ) phase is observed. The stability region of the trigonal phase has been found to be up to 22.6 GPa, above which the trigonal phase transforms to a cubic (SG : P m -3 n ) phase which remains stable until the maximum pressure of 29 GPa achieved in this study. A third-order Birch-Murnaghan equation of state fit to the pressure volume (P -V ) data yields a bulk modulus of 17.7(9) GPa for the trigonal phase. Raman spectroscopic measurements however indicate three-phase transitions at ˜1.3 ,4.0 , and 22.6 GPa, respectively. The electrical resistance measured in the low-pressure region up to 8 GPa indicates an electronic transition at around 4 GPa confirming the Raman result observed at 4.0 GPa. The P -V data when transformed to the universal equation of state (UEOS) show a deviation from linearity around 4.0 GPa confirming the electronic transition. The present study has thus revealed a three-phase structural sequence in alkali trihalides, viz., orthorhombic (SG: Pnma) to trigonal (SG : P -3 c 1 ) to a cubic (SG : P m -3 n ) phase.

  18. Synthesis, crystal structure, and optical property of the quaternary chalcohalide Ba{sub 4}Sb{sub 3}S{sub 8}Cl

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hua-Jun, E-mail: cszzl772002@yeah.net [Laboratory of Applied Research on the Characteristic Resources in the North of Guizhou Province, School of Chemistry and Chemical Engineering, Zunyi Normal College, Zunyi, Guizhou 563002 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    2016-03-15

    The quaternary chalcohalide Ba{sub 4}Sb{sub 3}S{sub 8}Cl has been prepared from stoichiometric mixtures of BaCl{sub 2}, Ba, Sb, and S at 1093 K in an evacuated silica tube. Ba{sub 4}Sb{sub 3}S{sub 8}Cl crystallizes in the monoclinic P2{sub 1}/c space group and features a 0D structure containing totally isolated [SbS{sub 3}]{sup 3−} units and discrete SbS{sub 2}Cl trigonal pyramids separated by Ba{sup 2+} cations. The [SbS{sub 3}]{sup 3−} units and SbS{sub 2}Cl trigonal pyramids are further packed in a pseudolayer motif in bc plane, respectively. The [SbS{sub 3}]{sup 3−} units are built by dimeric Sb{sub 2}S{sub 6} polyhedras and SbS{sub 3} trigonal pyramids. Within the dimeric Sb{sub 2}S{sub 6} polyhedra, two SbS{sub 4} seesaws share edges, while two SbS{sub 3} trigonal pyramids share corners with dimeric Sb{sub 2}S{sub 6} polyhedra. The optical gap of 2.09 eV for Ba{sub 4}Sb{sub 3}S{sub 8}Cl was deduced from the UV/Vis reflectance spectroscopy. - Graphical abstract: The quaternary chalcohalide Ba{sub 4}Sb{sub 3}S{sub 8}Cl has been prepared, which contains totally isolated [SbS{sub 3}]{sup 3−} units and discrete SbS{sub 2}Cl trigonal pyramids with Ba{sup 2+} cations located between them. - Highlights: • The quaternary chalcohalide Ba{sub 4}Sb{sub 3}S{sub 8}Cl has been prepared by solid-state reaction. • This material crystallizes in a new structure type with totally isolated [SbS{sub 3}]{sup 3−} units and discrete SbS{sub 2}Cl trigonal pyramids separated by Ba{sup 2+} cations. • The optical gap of 2.09 eV for Ba{sub 4}Sb{sub 3}S{sub 8}Cl was deduced from UV/Vis reflectance spectroscopy.

  19. Solvothermal synthesis of uranium(VI) phases with aromatic carboxylate ligands: A dinuclear complex with 4-hydroxybenzoic acid and a 3D framework with terephthalic acid

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yingjie, E-mail: yzx@ansto.gov.au [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Karatchevtseva, Inna [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Bhadbhade, Mohan [Mark Wainwright Analytical Centre, University of New South Wales, Kensington, NSW 2052 (Australia); Tran, Toan Trong; Aharonovich, Igor [School of Physics and Advanced Materials, University of Technology Sydney, Ultimo, NSW 2007 (Australia); Fanna, Daniel J.; Shepherd, Nicholas D. [School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751 (Australia); Lu, Kim [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Li, Feng [School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751 (Australia); Lumpkin, Gregory R. [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

    2016-02-15

    With the coordination of dimethylformamide (DMF), two new uranium(VI) complexes with either 4-hydroxybenzoic acid (H{sub 2}phb) or terephthalic acid (H{sub 2}tph) have been synthesized under solvothermal conditions and structurally characterized. [(UO{sub 2}){sub 2}(Hphb){sub 2}(phb)(DMF)(H{sub 2}O){sub 3}]·4H{sub 2}O (1) has a dinuclear structure constructed with both pentagonal and hexagonal bipyramidal uranium polyhedra linked through a µ{sub 2}-bridging ligand via both chelating carboxylate arm and alcohol oxygen bonding, first observation of such a coordination mode of 4-hydroxybenzoate for 5 f ions. [(UO{sub 2})(tph)(DMF)] (2) has a three-dimensional (3D) framework built with pentagonal bipyramidal uranium polyhedra linked with µ{sub 4}-terephthalate ligands. The 3D channeled structure is facilitated by the unique carboxylate bonding with nearly linear C–O–U angles and the coordination of DMF molecules. The presence of phb ligands in different coordination modes, uranyl ions in diverse environments and DMF in complex 1, and tph ligand, DMF and uranyl ion in complex 2 has been confirmed by Raman spectroscopy. In addition, their thermal stability and photoluminescence properties have been investigated. - Graphical abstract: With the coordination of dimethylformamide, two new uranyl complexes with either 4-hydroxybenzoate or terephthalate have been synthesized under solvothermal conditions and structurally characterized. - Highlights: • Solvent facilitates the synthesis of two new uranium(VI) complexes. • A dinuclear complex with both penta- and hexagonal bipyramidal uranium polyhedral. • A unique µ{sub 2}-bridging mode of 4-hydroxybenzoate via alcohol oxygen for 5 f ions. • A 3D framework with uranium polyhedra and µ{sub 4}-terephthalate ligands. • Vibration modes and photoluminescence properties are reported.

  20. Time-resolved assembly of chiral uranyl peroxo cage clusters containing belts of polyhedra.

    Science.gov (United States)

    Qiu, Jie; Nguyen, Kevin; Jouffret, Laurent; Szymanowski, Jennifer E S; Burns, Peter C

    2013-01-07

    Two chiral cage clusters built from uranyl polyhedra and (HPO(3))(2-) groups have been synthesized in pure yield and characterized structurally and spectroscopically in the solid state and aqueous solution. Synthesis reactions under ambient conditions in mildly acidic aqueous solutions gave clusters U(22)PO(3) and U(28)PO(3) that contain belts of four uranyl peroxide pentagonal and hexagonal bipyramids, in contrast to earlier reported uranyl peroxide cage clusters that are built from four-, five-, and six-membered rings of uranyl hexagonal bipyramids. U(22)PO(3) and U(28)PO(3) are also the first chiral uranyl-based cage clusters, the first that contain uranyl pentagonal bipyramids that contain no peroxide ligands, and the first that incorporate (HPO(3))(2-) bridges between uranyl ions. They are built from 22 uranyl polyhedra and 20 (HPO(3))(2-) groups, or 28 uranyl polyhedra and 24 (HPO(3))(2-) groups, with the outer and inner surfaces of the cages passivated by the O atoms of uranyl ions. Small-angle X-ray scattering (SAXS) profiles demonstrated that U(22)PO(3) clusters formed in solution within 1 h after mixing of reactants, and remained in solution for 2 weeks prior to crystallization. Time-resolved electrospray ionization mass spectrometry and SAXS demonstrated that U(28)PO(3) clusters formed in solution within 1 h of mixing the reactants, and remained in solution 1 month before crystallization. Crystallization of U(22)PO(3) and U(28)PO(3) is accelerated by addition of KNO(3). Clusters of U(22)PO(3) with and without encapsulated cations exhibit markedly different aqueous solubility, reflecting the importance of cluster surface charge in fostering linkages through counterions to form a stable solid.

  1. Rich Non-centrosymmetry in a Na-U-Te Oxo-System Achieved under Extreme Conditions.

    Science.gov (United States)

    Xiao, Bin; Kegler, Philip; Bosbach, Dirk; Alekseev, Evgeny V

    2016-05-02

    Two new sodium uranyl tellurites and two new sodium uranyl tellurates have been synthesized from high-temperature/high-pressure conditions and structurally characterized. We demonstrated that crystalline phases, forming in a Na-U-Te system under extreme conditions, appear to favorably have non-centrosymmetric structures. Three out of four novel uranyl tellurium compounds, Na[(UO2)Te(IV)2O5(OH)], Na2[(UO2)(Te(VI)2O8)], and Na2[(UO2)Te(VI)O5], crystallize in non-centrosymmetric space groups. The crystal structure of Na[(UO2)Te(IV)2O5(OH)] is based on two-dimensional [UO2Te2O5(OH)](-) corrugated sheets, which are charge balanced by guest Na(+) cations. The structure of Na2[(UO2)Te(VI)2O8] is constructed from [(UO2)2Te2O8](2+) anionic layers composed of UO7 pentagonal bipyramids and TeO6 octahedra. Na2[(UO2)(Te(VI)O5)] is a new type of three-dimensional anionic open framework built from the interconnection of UO7 pentagonal bipyramids and TeO6 octahedra with different types of interlacing channels within the U-Te anionic framework. Na[(UO2)Te(IV)6O13(OH)], as the only centrosymmetric compound isolated in the Na-U-Te family, is crystallized in space group Pa3̅, and its structure is highly related to that of cliffordite (UO2(Te3O7)), which is composed from UO8 hexagonal bipyramids and TeO5 square pyramids. The vibrational modes associated with U-O, Te(IV)-O, and Te(VI)-O bonds are discussed, and the Raman spectra of the four compounds are characterized for signature bands.

  2. NEW COMPLEX SELENITO AND OXALATO ADDUCTS CONTAINING SnPh3 AND SnPh2 RESIDUES: SYNTHESIS AND SPECTROSCOPIC STUDIES

    Directory of Open Access Journals (Sweden)

    SEYDI MANSOUR SECK

    2012-06-01

    Full Text Available Three new organotin complexes (two selenito and an oxalate one adducts have been synthesized and studied by infrared and Mössbauer techniques. A discrete structure is suggested with a bi-unidentate selenito oxyanion and trans bipyramidal SnPh3 residue; the oxalato adduct can be seen as an insertion compound between C2O4(SnPh32 and [Cu(En3]C2O4•4SnPh2C2O4. This last compound has a discrete ionic structure with cis coordinated SnPh2 residues.

  3. STUDY OF POLYMORPHISM OF BOROVANADATE GLASS OF ...

    African Journals Online (AJOL)

    de chaînes métavanadates doubles, les atomes V étant entouré par cinq atomes O pour former une bipyramide trigonale déformée [6]. L'analyse par XRD de cet échantillon traité thermiquement révèle que les deux espèces NaVO3.2H2O et Na2B4O7.5H2O ont cristallisé bien qu'aucune raie correspondant aux cristaux ...

  4. Hexa-μ-chlorido-hexachlorido(η6-hexamethylbenzenetrialuminium(IIIlanthanum(III benzene solvate

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available In the title compound, [Al3LaCl12(C12H18]·C6H6, all molecules are located on a mirror plane. Three chloridoaluminate groups and a hexamethylbenzene molecule are bound to the central lanthanum(III ion, forming a distorted pentagonal bipyramid with the η6-coordinated arene located at the apical position. The hexamethylbenzene ligand disordered between two orientations in a 1:1 ratio is also involved in parallel-slipped π–π stacking intermolecular interactions with a benzene solvent molecule [centroid–centroid distance 3.612 (4 Å].

  5. Poly[(μ4-3-carboxypyrazine-2-carboxylato(μ4-nitratodilithium

    Directory of Open Access Journals (Sweden)

    Wojciech Starosta

    2013-01-01

    Full Text Available In the title compound, [Li2(C6H3N2O42(NO3]n, the two symmetry-independent LiI ions are each in a trigonal–bipyramidal coordination and are bridged by N,O-bonding ligands, forming molecular ribbons propagating in [010]. Each LiI ion is also coordinated by two O atoms from nitrate ions, connecting the ribbons into a three-dimensional network. Very strong intramolecular O—H...O hydrogen bonds occur between the carboxyl and the carboxylate group.

  6. Dibromido(2,9-dimethyl-1,10-phenanthroline-κ2N,N′(dimethyl sulfoxide-κOcadmium

    Directory of Open Access Journals (Sweden)

    Khadijeh Moghanlou

    2013-01-01

    Full Text Available In the molecule of the title compound, [CdBr2(C14H12N2(C2H6OS], the CdII atom is five-coordinated in a distorted trigonal–bipyramidal configuration by two N atoms from a 2,9-dimethyl-1,10-phenanthroline ligand, one O atom from a dimethyl sulfoxide ligand and two Br atoms. In the crystal, π–π contacts between the pyridine and benzene rings [centroid–centroid distances = 3.710 (5, 3.711 (6 and 3.627 (5 Å] stabilize the structure.

  7. Triaqua(1,10-phenanthroline-2,9-dicarboxylatocobalt(II dihydrate

    Directory of Open Access Journals (Sweden)

    Zi-Fa Shi

    2010-04-01

    Full Text Available The title compound, [Co(C14H6N2O4(H2O3]·2H2O, has twofold crystallographic symmetry. The CoII atom is in a distorted pentagonal-bipyramidal coordination environment with two N atoms and two O atoms from a tetradentate 1,10-phenanthroline-2,9-dicarboxylate ligand and one O atom from a water molecule forming the pentagonal plane, and two O atoms from two water molecules occupying axial positions. In the crystal, adjacent molecules are linked by O—H...O hydrogen bonds, forming a three-dimensional network.

  8. Cyanidotetrakis(trimethylphosphinecobalt(I

    Directory of Open Access Journals (Sweden)

    Xiaofeng Xu

    2011-04-01

    Full Text Available The title compound, [Co(CN(C3H9P4], was obtained as a product of the reaction of [Co(PMe34] with a molar equivalent of 2,6-difluorobenzonitrile in diethyl ether. This compound is stable in the air for several hours, but rapidly decomposes at room temperature in solution. The cobalt(I atom has s trigonal–bipyramidal coordination enviroment in which the cyano group and one of the PMe3 groups are in the axial positions.

  9. Tribenzylchlorido(triphenylphosphine oxide-κOtin(IV

    Directory of Open Access Journals (Sweden)

    Kong Mun Lo

    2011-06-01

    Full Text Available In the title tribenzylchloridotin–triphenylphosphine adduct, [Sn(C7H73Cl(C18H15OP], the SnIV atom is in a trans-C3SnClO trigonal–bipyramidal geometry and is displaced out of the C3Sn girdle in the direction of the axial Cl atom by 0.112 (1 in one independent molecule and by 0.167 (1 Å in the other. The phenyl ring of one of the six benzyl units was refined as equally disordered over two sets of sites.

  10. (2-Hydroxybenzoato-κOtriphenyl(triphenylphosphine oxide-κOtin(IV

    Directory of Open Access Journals (Sweden)

    Dame Seye

    2016-11-01

    Full Text Available The title compound, [Sn{C6H4(OHCOO}(C6H53{OP(C6H53}], is comprised of discrete molecules with the SnIV atom in a trigonal–bipyramidal coordination environment. The carboxylate O atom of the salicylate anion and the O atom of the triphenylphosphine oxide moiety are in the axial positions and the three ipso C atoms occupy the equatorial positions. An intramolecular O—H...O hydrogen bond is present in the anion between the hydroxy group and the carbonyl atom O of the carboxylate group.

  11. Characterization of a Bacillus thuringiensis strain collection isolated from diverse Costa Rican natural ecosystems.

    Science.gov (United States)

    Arrieta, Glen; Espinoza, Ana M

    2006-03-01

    Costa Rican natural ecosystems are among the most diverse in the world. For this reason, we isolated strains of the entomopathogenic bacteria Bacillus thuringiensis (Bt) to determine their diversity, distribution and abundance. A total of 146 Bt strains were obtained from environmental samples collected from diverse natural ecosystems and life zones of Costa Rica. We recovered Bt strains from 71%, 63%, 61% and 54% of soil samples, fresh leaves, other substrates and leaf litter respectively. Bt was isolated in 65% of the samples collected in the humid tropical forest in national parks (Braulio Carrillo, Gandoca Manzanillo, Sierpe, Hitoy Cerere, and Cahuita), and in 59% of the samples collected in the dry tropical forest (Parque Nacional Marino las Baulas, Palo Verde and Santa Rosa). In the very humid tropical forest (Tortuguero) Bt was isolated in 75% of the samples and in the very humid tropical forest transition perhumid (Carara) it was found in 69% of the samples. The strains exhibit a diverse number, size and morphology of parasporal inclusion bodies: irregular (47%), oval (20%), bipyramidal (3%), bipyramidal and cubic (1%), bipyramidal, oval and irregular (5%) and bipyramidal, oval and cubic crystals (2%). Strains isolated from Braulio Carrillo, Tortuguero and Cahuita, presented predominantly irregular crystals. On the other hand, more than 60% of the isolates from Térraba-Sierpe and Hitoy-Cerere had medium oval crystals. Strains from Gandoca-Manzanillo, Palo Verde and Carara presented mainly combinations of oval and irregular crystals. Nevertheless, the greatest diversity in crystal morphology was observed in those from Santa Rosa, Llanos del Rio Medio Queso and Parque Marino las Baulas. Protein analyses of the crystal-spore preparations showed delta-endotoxin with diverse electrophoretic patterns, with molecular weights in the range of 20 to 160 kDa. Fifty six percent of the strains amplified with the cry2 primer, 54% with vip3, 20% with cry1, 9% with cry3

  12. Dichlorido[1-(1,10-phenanthrolin-2-yl-2-pyridone]cadmium(II

    Directory of Open Access Journals (Sweden)

    Jin-Min Li

    2008-08-01

    Full Text Available In the title mononuclear complex, [CdCl2(C17H11N3O], the CdII ion assumes a distorted trigonal–bipyramidal coordination geometry. The pyridone plane is twisted out of the 1,10-phenanthroline mean plane by 43.8 (3°. In the crystal structure, short intermolecular distances [3.627 (4–3.671 (4 Å] between the centroids of the six- and five-membered Cd-containing rings suggest the existence of π–π interactions, which link the molecules into stacks along the a axis.

  13. Bis(μ2-N-methyl-N-phenyldithiocarbamato-κ3S,S′:S;κ3S:S,S′-bis[(N-methyl-N-phenyldithiocarbamato-κ2S,S′cadmium]: crystal structure and Hirshfeld surface analysis

    Directory of Open Access Journals (Sweden)

    Siti Aisyah Nabilah Suwardi

    2017-03-01

    Full Text Available The title compound, [Cd2(C8H8NS24], is a centrosymmetric dimer with both chelating and μ2-tridentate dithiocarbamate ligands. The resulting S5 donor set defines a CdII coordination geometry intermediate between square-pyramidal and trigonal–bipyramidal, but tending towards the former. The packing features C—H...S and C—H...π interactions, which generate a three-dimensional network. The influence of these interactions, along with intra-dimer π–π interactions between chelate rings, has been investigated by an analysis of the Hirshfeld surface.

  14. Triaquabis(1H-imidazolebis[μ2-2-(oxaloaminobenzoato(3−]dicopper(IIcalcium(II heptahydrate

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2008-02-01

    Full Text Available In the title heterotrinuclear coordination compound, [CaCu2(C9H4NO52(C3H4N22(H2O3]·7H2O, the Ca2+ cation is in a pentagonal–bipyramidal geometry and bridges two (1H-imidazole[2-(oxaloaminobenzoato(3−]copper(II units in its equatorial plane. Each CuII atom has a normal square-planar geometry. The molecule has approximate local (non-crystallographic mirror symmetry and 23 classical hydrogen bonds are found in the crystal structure.

  15. Dichlorido[methyl 2-(quinolin-8-yloxy-κ2N,Oacetate-κO]mercury(II

    Directory of Open Access Journals (Sweden)

    Yu-Hong Wang

    2012-07-01

    Full Text Available In the neutral title complex, [HgCl2(C12H11NO3], the HgII ion is pentacoordinated by two Cl atoms, one N atom and two weakly coordinating O atoms from the methyl 2-(quinolin-8-yloxyacetate ligand. The coordination around the HgII ion may be described as highly distorted trigonal–bipyramidal. Centrosymmetric dimers are formed by an additional weak Hg...Cl interaction, leading to a distorted octahedral coordination geometry around the HgII ion.

  16. Charcot-Leyden crystals: pathology and diagnostic utility.

    Science.gov (United States)

    Pantanowitz, Liron; Balogh, Karoly

    2004-07-01

    Eosinophilia is associated with several diseases of the upper respiratory tract. The predominance of eosinophils in nasal tissue, secretions, and lavage fluid has been used as an aid in the diagnosis of allergic rhinitis. Charcot-Leyden crystals, considered to be a morphologic hallmark of eosinophil-related disease, are often also found in inflamed nasal tissue and paranasal sinus contents of patients with allergic rhinitis. These bipyramidal-shaped crystals are composed of the enzyme lysolecithin acylhydrolase, one of several eosinophilic proteins that damage respiratory epithelium and contribute to the pathology of allergy in the upper respiratory tract.

  17. Crystalline inclusions in granulocytic sarcoma.

    Science.gov (United States)

    Strauchen, James A; Gordon, Ronald E

    2002-01-01

    Two cases of granulocytic sarcoma were found to contain numerous crystalline inclusions identified on hematoxylin-eosin-stained sections as clusters of pointed needlelike crystals present in foci of necrosis or within macrophages. The crystals were negative for chloroacetate esterase and myeloperoxidase. Electron microscopy demonstrated homogeneously dense, bipyramidal structures, indistinguishable from Charcot-Leyden crystals. Granulocytic sarcomas may contain crystalline inclusions similar to Charcot-Leyden crystals; these structures should be distinguished from crystalline immunoglobulin inclusions occurring in cases of plasma cell myeloma and lymphoplasmacytic lymphoma, which may have a similar appearance.

  18. Crystal structure of [tris(pyridin-2-ylmethylamine-κ4N]copper(II bromide

    Directory of Open Access Journals (Sweden)

    Emma C. Bridgman

    2016-06-01

    Full Text Available In the asymmetric unit of the title compound, [CuBr(C18H18N4]Br, there are three crystallographically independent cations. One of the cations exhibits positional disorder of the pyridin-2-ylmethyl groups over two sets of sites with refined occupancies of 0.672 (8 and 0.328 (8. The outer-sphere bromine counter-ion is severely disordered over multiple sites. In each cation, the CuII ion is coordinated by the four N atoms of the tris(pyridin-2-ylmethylamine ligand and one bromine and adopts a slightly distorted trigonal–bipyramidal geometry.

  19. Dichlorido(4′-ferrocenyl-2,2′:6′,2′′-terpyridine-κ3N,N′,N′′zinc acetonitrile monosolvate

    Directory of Open Access Journals (Sweden)

    Si-Ping Tang

    2011-08-01

    Full Text Available The title complex, [FeZn(C5H5Cl2(C20H14N3]·CH3CN, is composed of one ZnII atom, one 4′-ferrocenyl-2,2′:6′,2′′-terpyridine (fctpy ligand, two Cl atoms and one acetonitrile solvent molecule. The ZnII atom is five-coordinated in a trigonal–bipyramidal geometry by the tridentate chelating fctpy ligand and two Cl atoms.

  20. Crystal structure of dioxidobis(pentane-2,4-dionato-κ2 O,O′)[1-phenyl-3-(pyridin-4-yl)propane-κN]uranium(VI)

    Science.gov (United States)

    Kawasaki, Takeshi; Kitazawa, Takafumi

    2015-01-01

    In the title compound, [UO2(C5H7O2)2(C14H15N)], the uran­yl(VI) unit ([O=U=O]2+) is coordinated to two acetyl­acetonate (acac) anions and one 1-phenyl-3-(pyridin-4-yl)propane (ppp) mol­ecule. The geometry around the U atom is UNO6 penta­gonal–bipyramidal; two uran­yl(VI) O atoms are located at the axial positions, whereas four O atoms from two chelating bidentate acac ligands and one N atom of a ppp ligand form the equatorial plane. PMID:25705446

  1. Di-μ-chlorido-bis-[chloridobis(dimethyl sulfoxide)dioxidouranium(VI)].

    Science.gov (United States)

    Takao, Koichiro; Ikeda, Yasuhisa

    2007-12-06

    In the crystal structure of the title compound, [U(2)Cl(4)O(4)(C(2)H(6)OS)(4)], the compound has a centrosymmetric dimeric structure bridged by two chloride anions. Each U(VI) atom is seven-coordinate in a penta-gonal-bipyramidal geometry. In the equatorial plane of the uranyl unit there are two O atoms from non-adjacent dimethyl sulfoxides and three chloride ions (of which two chlorides are bridging). The compound is of inter-est as an anhydrous starting material of the uran-yl(VI) ion.

  2. Crystal structure of dioxidobis(pentane-2,4-dionato-κ(2) O,O')[1-phenyl-3-(pyridin-4-yl)propane-κN]uranium(VI).

    Science.gov (United States)

    Kawasaki, Takeshi; Kitazawa, Takafumi

    2015-01-01

    In the title compound, [UO2(C5H7O2)2(C14H15N)], the uran-yl(VI) unit ([O=U=O](2+)) is coordinated to two acetyl-acetonate (acac) anions and one 1-phenyl-3-(pyridin-4-yl)propane (ppp) mol-ecule. The geometry around the U atom is UNO6 penta-gonal-bipyramidal; two uran-yl(VI) O atoms are located at the axial positions, whereas four O atoms from two chelating bidentate acac ligands and one N atom of a ppp ligand form the equatorial plane.

  3. catena-Poly[[triphenyltin(IV]-μ-phenylphosphinato-κ2O:O′

    Directory of Open Access Journals (Sweden)

    Tidiane Diop

    2011-12-01

    Full Text Available In the structure of the title coordination polymer, [Sn(C6H53(C6H6O2P]n or [PhP(HO2SnIV(Ph3]n, the SnIV atom is five-coordinate, with the SnC3O2 framework in a trans trigonal–bipyramidal arrangement having the PhP(HO2− anions in apical positions. In the crystal, neighbouring polymer chains are linked via C—H...π interactions, forming a two-dimensional network lying parallel to (001.

  4. Tris(1,2-dimethoxyethane-κ2O,O′iodidocalcium iodide

    Directory of Open Access Journals (Sweden)

    Siou-Wei Ou

    2012-02-01

    Full Text Available In the title complex, [CaI(C4H10O23]I, the CaII atom is seven-coordinated by six O atoms from three 1,2-dimethoxyethane (DME ligands and one iodide anion in a distorted pentagonal–bipyramidal geometry. The I atom and one of the O atoms from a DME ligand lie in the axial positions while the other O atoms lie in the basal plane. The other iodide anion is outside the complex cation.

  5. Rationally designed peptide nanosponges for cell-based cancer therapy.

    Science.gov (United States)

    Wang, Hongwang; Yapa, Asanka S; Kariyawasam, Nilusha L; Shrestha, Tej B; Kalubowilage, Madumali; Wendel, Sebastian O; Yu, Jing; Pyle, Marla; Basel, Matthew T; Malalasekera, Aruni P; Toledo, Yubisela; Ortega, Raquel; Thapa, Prem S; Huang, Hongzhou; Sun, Susan X; Smith, Paul E; Troyer, Deryl L; Bossmann, Stefan H

    2017-11-01

    A novel type of supramolecular aggregate, named a "nanosponge" was synthesized through the interaction of novel supramolecular building blocks with trigonal geometry. The cholesterol-(K/D)nDEVDGC)3-trimaleimide unit consists of a trigonal maleimide linker to which homopeptides (either K or D) of variable lengths (n=5, 10, 15, 20) and a consensus sequence for executioner caspases (DEVDGC) are added via Michael addition. Upon mixing in aqueous buffer cholesterol-(K)nDEVDGC)3-trimaleimides and a 1:1 mixture of cholesterol-(K/D)nDEVDGC)3-trimaleimides form stable nanosponges, whereas cholesterol-(D)nDEVDGC)3-trimaleimide is unable to form supramolecular aggregates with itself. The structure of the novel nanosponges was investigated through explicit solvent and then coarse-grained molecular dynamics (MD) simulations. The nanosponges are between 80 nm and several micrometers in diameters and virtually non-toxic to monocyte/macrophage-like cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Unravelling the interplay of geometrical, magnetic and electronic properties of metal-doped graphene nanomeshes

    KAUST Repository

    Fadlallah, Mohamed M.

    2016-12-02

    Graphene nanomeshes (GNMs), formed by creating a superlattice of pores in graphene, possess rich physical and chemical properties. Many of these properties are determined by the pore geometry. In this work, we use first principles calculations to study the magnetic and electronic properties of metal-doped nitrogen-passivated GNMs. We find that the magnetic behaviour is dependent on the pore shape (trigonal versus hexagonal) as dictated by the number of covalent bonds formed between the 3d metal and the passivating N atoms. We also find that Cr and V doped trigonal-pore GNMs, and Ti doped GNMs are the most favourable for spintronic applications. The calculated magnetic properties of Fe-doped GNMs compare well with recent experimental observations. The studied systems are useful as spin filters and chemical sensors.

  7. Poly[tetraaqua-μ4-bromido-di-μ2-bromido-μ2-hydroxido-di-μ3-isonicotinato-tetra-μ2-isonicotinato-tetracopper(Idithulium(III

    Directory of Open Access Journals (Sweden)

    Hui-Luan Liu

    2008-10-01

    Full Text Available A new thulium(III–copper(I heterometallic coordination polymer, [Cu4Tm2Br3(C6H4NO26(OH(H2O4]n, has been prepared by a hydrothermal method. The Tm and both Cu atoms lie on mirror planes. The Tm atom is seven-coordinate with a capped distorted trigonal–prismatic coordination geometry, while the Cu atoms adopt trigonal CuBrN2 and tetrahedral CuBr3N coordination modes, respectively. The Cu atom in the trigonal coordination environment is disordered over two sites of equal occupancy. The crystal structure is constructed from two distinct units of dimeric [Tm2(μ2-OH(IN6(H2O4] cores (IN = isonicotinate and one-dimensional inorganic [Cu4Br3]n chains, which are linked together, forming heterometallic Cu–halide–lanthanide–organic layers.

  8. Complex [Cd(dafo) 2(tphpo)(CH 3COO)]ClO 4 (dafo=4,5-diazafluoren-9-one, tphpo=triphenylphosphine oxide) with chiral metal centers. Helical packing induced by π-π stacking interactions of dafo rings

    Science.gov (United States)

    Wu, B.-L.; Zhang, H.-Y.; Wu, Q.-A.; Hou, H.-W.; Zh, Y.

    2003-08-01

    The first complex of 4,5-diazafluoren-9-one (dafo) and cadmium: [Cd(dafo) 2(tphpo)(CH 3COO)]ClO 4 (triphenylphosphine oxide=tphpo) is a quaternary complex with chiral metal centers and crystallizes in a monoclinic cell with space group P2(1)/ n. Cadmium centers with 7-fold coordination adopt a distorted monocapped trigonal prismatic geometry. Two oxygen atoms of acetate and one oxygen atom of triphenylphosphine oxide form the top triangle of the trigonal prism, while three nitrogen atoms from two dafo groups construct the bigger bottom triangle. The last nitrogen atom of dafo groups occupies the monocapped position. Here, dafo molecules display two different coordination patterns, namely unsymmetric and symmetric chelation. Moreover, the interesting linking of screw related cations is fabricated by inter-molecular π-π stacking interactions in the complex.

  9. NCBI nr-aa BLAST: CBRC-TBEL-01-0595 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available ovine Rhodopsin (Metarhodopsin Ii) pdb|1GZM|A Chain A, Structure Of Bovine Rhodopsin In A Trigonal Crystal F...orm pdb|1GZM|B Chain B, Structure Of Bovine Rhodopsin In A Trigonal Crystal Form pdb|1HZX|A Chain A, Cryst...al Structure Of Bovine Rhodopsin pdb|1HZX|B Chain B, Crystal Structure Of Bovine Rh...odopsin pdb|1L9H|A Chain A, Crystal Structure Of Bovine Rhodopsin At 2.6 Angstroms Resolution pdb|1L9H|B Chain B, Crystal... Structure Of Bovine Rhodopsin At 2.6 Angstroms Resolution pdb|1U19|A Chain A, Crystal

  10. Computed tomographic findings in children with spastic diplegia; Correlation with the severity of their motor abnormality

    Energy Technology Data Exchange (ETDEWEB)

    Yokochi, Kenji; Horie, Masayo; Inukai, Kazuhisa; Kito, Hideyuki (Seirei-Mikatabara General Hospital, Shizuoka (Japan)); Shimabukuro, Satoshi; Kodama, Kazuo

    1989-08-01

    Computed tomographic findings of 46 children with spastic diplegia examined at nine months to three years of age corrected for preterm births were analyzed. Both the size of the lateral ventricles measured by the width of the anterior horns, and the volume of the extracerebral low-density areas were enlarged in some patiens. Both enlargements did not, however, correlate to the severity of the motor abnormality in the patients. The low-density areas of the periventricular white matter, especially adjacent to the trigone, were reduced in many children, probably due to the atrophy of the cerebral white matter having periventricular leukomalacia. The anterior expansion of the white matter reduction from the trigone corresponded to the severer motor abnormality in the children with spastic diplegia. (author).

  11. Coupling of ferroelasticity and ferromagnetism in La1-xSrxCoO3 twin crystals

    Science.gov (United States)

    Kyômen, Tôru; Sano, Akito; Murachi, Yohei; Hanaya, Minoru; Suzuki, Kosuke; Ito, Masahisa

    2010-08-01

    In the present study, x-ray diffraction experiments under magnetic fields were carried out for La0.57Sr0.44CoO3.01 twin crystals with a trigonal structure by Laue method in addition to magnetization measurements. Crystallographic domains (variants) in a ferromagnetic phase of the crystals were rearranged by applying magnetic fields and the rearranged structure remained even after the applied magnetic fields were changed to zero, indicating a coupling of ferroelasticity and ferromagnetism. The present results were consistently understood by the large uniaxial magnetocrystalline anisotropy with an easy plane of magnetization parallel to the hexagonal ab plane of the trigonal structure. The origin of the large magnetocrystalline anisotropy was discussed in relation to the spin states of Co ions.

  12. Numerical Simulation of Squeezing Failure in a Coal Mine Roadway due to Mining-Induced Stresses

    Science.gov (United States)

    Gao, Fuqiang; Stead, Doug; Kang, Hongpu

    2015-07-01

    Squeezing failure is a common failure mechanism experienced in underground coal mine roadways due mainly to mining-induced stresses, which are much higher than the strength of rock mass surrounding an entry. In this study, numerical simulation was carried out to investigate the mechanisms of roadway squeezing using a novel UDEC Trigon approach. A numerical roadway model was created based on a case study at the Zhangcun coal mine in China. Coal extraction using the longwall mining method was simulated in the model with calculation of the mining-induced stresses. The process of roadway squeezing under severe mining-induced stresses was realistically captured in the model. Deformation phenomena observed in field, including roof sag, wall convexity and failed rock bolts are realistically produced in the UDEC Trigon model.

  13. Crystallization of the xeroderma pigmentosum group F endonuclease from Aeropyrum pernix.

    Science.gov (United States)

    Lally, John; Newman, Matthew; Murray-Rust, Judith; Fadden, Andrew; Kawarabayasi, Yutaka; McDonald, Neil

    2004-09-01

    The xeroderma pigmentosa group F protein (XPF) is a founding member of a family of 3'-flap endonucleases that play an essential role in nucleotide-excision repair, DNA replication and recombination. The XPF gene has been cloned from Aeropyrum pernix, encoding a 254-residue protein (apXPF). Recombinant protein was produced in Escherichia coli and purified by three chromatographic steps. Three different crystal forms of apXPF were grown in trigonal, monoclinic and triclinic systems. The trigonal crystals diffracted to 2.8 A and were grown in the presence of double-stranded DNA. Monoclinic crystals were grown without DNA and diffracted to 3.2 A. Triclinic crystals were grown from a truncated apXPF protein lacking the tandem helix-hairpin-helix motifs and diffracted to 2.1 A.

  14. Urinary bladder botryoid rhabdomyosarcoma with widespread metastases in an 8-month-old Labrador cross dog : clinical communication

    Directory of Open Access Journals (Sweden)

    K. Gerber

    2009-05-01

    Full Text Available An 8-month-old crossbred Labrador retriever was presented with a history and clinical signs suggestive of lower urinary tract obstruction. Laboratory results revealed azotaemia and hyperphosphataemia. Ultrasonographic evaluation of the urinary tract showed a mass at the bladder trigone, hydronephrosis, hyrodureter, and suspected metastases to lymph nodes and the liver. Pulmonary metastasis was identified on thoracic radiographs. A post mortem confirmed metastases to the liver, lungs and regional lymph nodes, as well as to the mesenteric lymph nodes, mediastinum, heart, subcutaneous tissue and several muscle groups. A histopathological diagnosis of metastatic botryoid rhabdomyosarcoma (sarcoma botryoides was made. A review of the literature shows that, although the bladder trigone is a well documented location for this tumour, this case was unique with its widespread metastases to previously undocumented organs. The incidence, embryology, ultrasonographic appearance and treatment of this tumour are discussed.

  15. Importance of t2g-eg hybridization in transition metal oxides

    Science.gov (United States)

    Landron, Sylvain; Lepetit, Marie-Bernadette

    2008-03-01

    We studied the influence of the trigonal distortion of the regular octahedron along the (111) direction, as found in the CoO2 layers. Under this distortion the t2g orbitals split into one a1g and two degenerate eg' orbitals. We focused on the relative order of these orbitals. Using quantum chemical calculations of embedded clusters at different levels of theory, we analyzed the influence of the different effects not taken into account in crystalline field theory; that is, metal-ligand hybridization, the long-range crystalline field, screening effects, and orbital relaxation. We found that none of them is responsible for the relative order of the t2g orbitals. In fact, the trigonal distortion allows a mixing of the t2g and eg orbitals of the metallic atom. This hybridization is at the origin of the a1g-eg' relative order and of the incorrect prediction of crystalline field theory.

  16. Domain Modeling: NP_653314.1 [SAHG[Archive

    Lifescience Database Archive (English)

    Full Text Available NP_653314.1 chr2 Crystal structure of an 8 repeat consensus TPR superhelix (trigona...l crystal form) p2hyza_ chr2/NP_653314.1/NP_653314.1_apo_256-390.pdb p2fo7a_ chr2/NP_653314.1/NP_653314.1_holo_256-390.pdb psi-blast 416K,417H,418Y,458N _CD 1 ...

  17. Domain Modeling: NP_689916.2 [SAHG[Archive

    Lifescience Database Archive (English)

    Full Text Available NP_689916.2 chr7 Crystal structure of an 8 repeat consensus TPR superhelix (trigona...l crystal form) p2hyza_ chr7/NP_689916.2/NP_689916.2_apo_473-607.pdb p2fo7a_ chr7/NP_689916.2/NP_689916.2_holo_473-607.pdb psi-blast 486T,487L,488N,529I,530L,531F _CD 1 ...

  18. Korobeiniku suurte plaanide algus / Jaanika Heinsoo

    Index Scriptorium Estoniae

    Heinsoo, Jaanika

    2005-01-01

    Tutvumis- ja suhtlemissait Rate.ee on Eesti enimkülastatud Internetisait, millel on üle 300 000 registreeritud kasutaja. Rate.ee omanik ning juht Andrei Korobeinik selgitab saidi fenomeni ning tutvustab selle kontseptsiooni ja laienemisplaane. Vt. samas Columbus IT juhatuse esimehe Ivo Suursoo ja Martinson Trigon Venture Partners'i tegevjuhi Allan Martinsoni kommentaare küsimusele "Mis on Rate.ee fenomen?"

  19. Chiari type 1 malformation and periventricular nodular heterotopia in a 6-year-old boy with congenital hemiplegia: a case report.

    Science.gov (United States)

    Kaushik, Jaya Shankar; Sharma, Suvasini; Aneja, Satinder; Kumar, Atin

    2014-01-01

    A 6-year-old boy presented with weakness of the right upper and lower limbs, noted since infancy. Magnetic resonance imaging of the brain revealed periventricular nodular heterotopia lining the trigone and occipital horns of bilateral lateral ventricles along with herniation of the cerebellar tonsils below the foramen magnum suggestive of Chiari type 1 malformation. The association of periventricular nodular heterotopia with Chiari type 1 malformation has not been described earlier in children.

  20. Tetrakis(μ-propanoato-κ2O:O′bis[(1,10-phenanthroline-κ2N,N′(propanoato-κ2O,O′samarium(III

    Directory of Open Access Journals (Sweden)

    Chun-Xiang Wang

    2008-01-01

    Full Text Available The title complex, [Sm2(C3H5O26(C12H8N22], is a dinuclear centrosymmetric molecule, in which two crystallographically equivalent Sm atoms, separated by 3.9502 (2 Å, are bridged by four propanoate anions. Each Sm atom is coordinated by two N atoms from one chelating phenanthroline ligand and seven carboxylate O atoms from five propanoate anions, to form a distorted tricapped trigonal prism.

  1. Rack-induced metal binding vs. flexibility: Met121His azurin crystal structures at different pH

    OpenAIRE

    Messerschmidt, Albrecht; Prade, Lars; Kroes, Sandra J.; Sanders–Loehr, Joann; Huber, Robert; Canters, Gerard W.

    1998-01-01

    The rack-induced bonding mechanism of metals to proteins is a useful concept for explaining the generation of metal sites in electron transfer proteins, such as the blue copper proteins, that are designed for rapid electron transfer. The trigonal pyramidal structure imposed by the protein with three strong equatorial ligands (one Cys and two His) provides a favorable geometry for both cuprous and cupric oxidation states. However, the crystal structures of the Met121His mutant of azurin from A...

  2. Polymorphism and thermodynamic ground state of Silver fulminate studied from van der Waals density functional calculations

    OpenAIRE

    Yedukondalu, N.; Vaitheeswaran, G.

    2014-01-01

    Silver fulminate (AgCNO) is a primary explosive, which exists in two polymorphic phases namely orthorhombic (\\emph{Cmcm}) and trigonal (\\emph{R$\\bar{3}$}) forms at ambient conditions. In the present study, we have investigated the effect of pressure and temperature on relative phase stability of the polymorphs using planewave pseudopotential approaches based on Density Functional Theory (DFT). van der Waals interactions play a significant role in predicting the phase stability and they can be...

  3. Domain Modeling: NP_055111.1 [SAHG[Archive

    Lifescience Database Archive (English)

    Full Text Available NP_055111.1 chr3 Crystal structure of an 8 repeat consensus TPR superhelix (trigona...l crystal form) p2hyza_ chr3/NP_055111.1/NP_055111.1_apo_10-158.pdb p2fo7a_ chr3/NP_055111.1/NP_055111.1_holo_10-158.pdb psi-blast 23E,24G,25R _CD 1 ...

  4. Pediatric intraventricular arachnoid cysts in the body of lateral ventricle: surgical outcome and its embryologic background.

    Science.gov (United States)

    Knie, Bettina; Morota, Nobuhito; Ihara, Satoshi; Tamura, Goichiro; Ogiwara, Hideki

    2016-11-01

    The aim of this study is for the surgical treatment and outcome of the endoscopic fenestration of the arachnoid cyst located in the ventricular body to trigone in the pediatric population. Special concern was paid for the developmental origin of the intraventricular cysts estimated from the postoperative follow-up neuroimagings. Between July 2002 and June 2015, we performed endoscopic and partly CT/MRI navigated fenestrations of intraventricular arachnoid cysts located at the body to trigone of the lateral ventricle in ten pediatric patients aged 2 months to 5 years. Based on the long axis of the cyst, we have opted for two surgical approaches: anterior approach via burr hole at Kocher's point and posterior approach via burr hole at the posterior occipital region. Fenestration was performed based on the intraoperative findings, either ventriculocystostomy, ventriculocystoventriculostomy, or ventriculocystocisternostomy. Intraventricular arachnoid cysts located in the body-trigone region showed a favorable outcome after endoscopic fenestration. All of the cysts shrank postoperatively. Follow-up neuroimagings taken between 6 and 126 months after surgery strongly suggested its relationship with the midline cisterns. Of our ten cases, eight were suggestive for originating from the velum interpositum cistern while two seemed to root from the quadrigeminal cistern. In the present study, we found that endoscopic fenestration of intraventricular arachnoid cysts in the body to trigone is a safe procedure with a satisfactory outcome. In our limited experience, there are two anatomic backgrounds; velum interpositum cistern and quadrigeminal cistern. Differentiation can be possible by neuroimagings, especially those obtained after surgery.

  5. Surfactant-directed synthesis of branched bismuth telluride/sulfide core/shell nanorods.

    Science.gov (United States)

    Purkayastha, Arup; Yan, Qingyu; Raghuveer, Makala S; Gandhi, Darshan D; Li, Huafang; Liu, Zhong W; Ramanujan, Raju V; Borca-Tasciuc, Theodorian; Ramanath, Ganapathiraman

    2008-07-17

    Branched core/shell bismuth telluride/bismuth sulfide nanorod heterostructures are prepared by using a biomimetic surfactant, L-glutathionic acid. Trigonal nanocrystals of bismuth telluride are encapsulated by nanoscopic shells of orthorhombic bismuth sulfide. Crystallographic twinning causes shell branching. Such heteronanostructures are attractive for thermoelectric power generation and cooling applications. Copyright © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. 4-(Diphenylaminobenzaldehyde

    Directory of Open Access Journals (Sweden)

    Hongli Wang

    2009-01-01

    Full Text Available In the title compound, C19H15NO, the N atom adopts an approximately trigonal-planar geometry, lying 0.07 (1 Å from the plane defined by its three neighbouring C atoms. The two phenyl rings and the benzaldehyde group form dihedral angles of 53.0 (1/47.2 (1 and 29.0 (1°, respectively, with this central plane.

  7. Synthesis and crystal structure of a chiral aromatic amine chloride salt (C8H12N)Cl

    Science.gov (United States)

    Ben Salah, A. M.; Naїli, H.; Mhiri, T.; Bataille, T.

    2015-12-01

    The new organic chloride salt incorporating an aromatic primary amine with a chiral functional group, (S)-α-methylbenzylammonium), has been synthesized by slow evaporation method at room temperature. The crystals are trigonal with non-centrosymmetric sp. gr. R3. The crystal packing is determined by N-H···Cl hydrogen bonds and C-H···π interactions between the aromatic rings of the organic moieties, resulting in supramolecular architecture.

  8. Domain Modeling: NP_001007524.1 [SAHG[Archive

    Lifescience Database Archive (English)

    Full Text Available NP_001007524.1 chrX Crystal structure of an 8 repeat consensus TPR superhelix (trig...onal crystal form) p2hyza_ chrX/NP_001007524.1/NP_001007524.1_apo_2-131.pdb p2fo7a_ chrX/NP_001007524.1/NP_001007524.1_holo_2-131.pdb psi-blast 155L,156G,157Q _CD 1 ...

  9. CHARACTERIZATION AND ELECTRICAL TRANSPORT-PROPERTIES OF THE MISFIT LAYER COMPOUNDS (BISE)1.10NBSE2 AND (BISE)1.09TASE2

    NARCIS (Netherlands)

    ZHOU, WY; MEETSMA, A; DEBOER, JL; WIEGERS, GA

    Compounds (BiSe)1.10NbSe2 and (BiSe)1.09TaSe2 were prepared by high-temperature reaction of the elements. Crystals were grown by vapor transport. The misfit layer compounds are built of alternate sandwiches NbSe2 (TaSe2) with Nb (Ta) in trigonal prisms of Se and interface modulated double layers of

  10. CRYSTAL-STRUCTURE DETERMINATION OF THE MISFIT LAYER COMPOUND (HOS)1.23NBS2

    NARCIS (Netherlands)

    WIEGERS, GA; MEETSMA, A; HAANGE, RJ; DEBOER, JL

    1992-01-01

    Single-crystal X-ray diffraction has shown that (HoS)1.23NbS2 is a misfit layer compound built of alternate double layers of HoS, approximately a {001} slice of NaCl-type HoS, and sandwiches of NbS2 with niobium in trigonal prisms of sulphur like niobium in 2H-NbS2. The unit cell dimensions of the

  11. catena-Poly[[hexakis(μ-4-methylbenzoato-κ2O,O′;κ15O,O′:O-trieuropium(III]-tris(μ-4-methylbenzoato-κ2O,O′;κ6O,O′:O

    Directory of Open Access Journals (Sweden)

    Chao-Hua Zhang

    2008-08-01

    Full Text Available The title europium(III carboxylate, [Eu3(C8H7O29]n, has three independent Eu atoms, two of which are eight-coordinate in a square-antiprismatic coordination geometry, whereas the third is nine-coordinate in a tricapped trigonal-prismatic coordination geometry. The metal atoms are linked by two bidentate and seven tridentate methylbenzoate groups into a linear chain running along the b-axis direction.

  12. Evolution and function of the upper molar talon and its dietary implications in microbats.

    Science.gov (United States)

    Gutzwiller, Sarah C; Hunter, John P

    2015-11-01

    The evolution of mammalian molars has been marked by transitions representing significant changes in shape and function. One such transition is the addition and elaboration of the talon, the distolingual region of the ancestral tribosphenic upper molar of therian mammals and some extinct relatives. This study uses suborder Microchiroptera as a case study to explore the adaptive implications of the expansion of the talon on the tribosphenic molar, specifically focusing on the talon's role in the compression and shear of food during breakdown. Three-dimensional computer renderings of casts of the upper left first molars were created for microbat species of a variety of dietary categories (frugivore, etc.) and physical properties of food (hard and soft). Relief Index (RFI) was measured to estimate the topography and function of the whole tooth and of the talon and trigon (the remaining primitive tribosphenic region) individually, in order to examine 1) how the shape of the whole tooth, trigon, and talon reflects the compromise between their crushing and shearing functions, 2) how whole tooth, trigon, and talon function differs according to diet, and 3) how the presence of the talon affects overall molar function. Results suggest that RFI of both the whole tooth and the trigon varies according to dietary groups, with frugivores having greater crushing function when compared with the other groups. The talon, however, consistently has low RFI (a flatter topography), and its presence lowers the RFI of the whole tooth across all dietary categories, suggesting that the talon is primarily functioning in crushing during food breakdown. The potential benefits of a crushing talon for microbats of various dietary groups are discussed. © 2015 Wiley Periodicals, Inc.

  13. R -ESONANCE

    Indian Academy of Sciences (India)

    [1] WalterRudin,Principles. ofjWathematical Analy- sis, McGraw Hill, Inter- national Student Edi- tion,1964. CLASSROOM. The entire edifice of trigonOI11etry can b(~ built using. C (t) S (t) and wdl-knuwn principles of Real Analysis. \\Ve have been a.hle to find our ,vay around withOll t (tn," help frol11 the extraterrestrial !=T.

  14. Fulltext PDF

    Indian Academy of Sciences (India)

    [1] WalterRudin,Principles. ofjWathematical Analy- sis, McGraw Hill, Inter- national Student Edi- tion,1964. CLASSROOM. The entire edifice of trigonOI11etry can b(~ built using. C (t) S (t) and wdl-knuwn principles of Real Analysis. \\Ve have been a.hle to find our ,vay around withOll t (tn," help frol11 the extraterrestrial !=T.

  15. Coherent control of optical phonons in bismuth

    Science.gov (United States)

    Cheng, Yu-Hsiang; Gao, Frank Y.; Teitelbaum, Samuel W.; Nelson, Keith A.

    2017-10-01

    We have conducted degenerate pump-pump-probe experiments on semimetal bismuth with femtosecond time resolution, varying both pump-probe and interpump time delays. The observed phonon dynamics, including the amplitude, damping, frequency, and phase, can be modeled by the interference of two chirped damped oscillators. No lattice anharmonicity along the trigonal axis is observed. We also find evidence of phonon-mediated relaxation of the energy density at the sample surface.

  16. Ultrasonographic diagnosis of unilateral ectopic ureter in a Labrador dog

    Directory of Open Access Journals (Sweden)

    P.A. Oglesby

    2003-07-01

    Full Text Available A 3-month-old, Labrador bitch presented with urinary incontinence. A unilateral, ectopic ureter was diagnosed with ultrasound without the aid of additional contrast radiographic techniques. Ipsilateral hydroureter and mild hydronephrosis were also present.At the level of the bladder trigone the ectopic ureter became intramural and this was clearly demonstrable with ultrasound. The opening of the ectopic ureter into the proximal urethra was, however, not visualised owing to its intrapelvic location.

  17. A high pressure infrared spectroscopic study of PbCO3-cerussite: constraints on the structure of the post-aragonite phase

    Science.gov (United States)

    Catalli, K.; Santillán, J.; Williams, Q.

    2005-09-01

    We have measured the infrared spectrum of aragonite-structured PbCO3-cerussite to 41 GPa at 300 K in the diamond anvil cell. We observed a phase transition from an orthorhombic to a trigonal structure beginning at 15 GPa, manifested by a splitting of the ν2-out-of-plane bending vibration and a broadening and dramatic decrease in amplitude of the ν1-symmetric stretching vibration of the carbonate group. While the locations of the ν1-symmetric stretching and ν4-in-plane bending bands are similar between the low- and high-pressure phases, their mode shifts and peak shapes change markedly near the transition. In particular, the ν1 symmetric stretch has an essentially zero pressure shift in the high pressure phase, and its dramatically enhanced peak width indicates that it may be symmetry forbidden. The decreased mode shifts of the carbonate vibrations after the phase transition suggest that the carbonate group is less compressible in the new structure. The spectral changes observed are consistent with a small, trigonal unit cell, with space group {Pbar{3}{1c}} and two formula units, instead of a previously proposed orthorhombic cell with sixteen formula units. This structure is identical to that of the high-pressure phase of BaCO3, and likely CaCO3 as well. Our results thus indicate that the post-aragonite, high-pressure phase of divalent-cation carbonates may be a comparatively high-symmetry trigonal structure.

  18. Electron paramagnetic resonance spectroscopy of lithium donors in monoisotopic silicon

    Science.gov (United States)

    Ezhevskii, Alexandr A.; Soukhorukov, Andrey V.; Guseinov, Davud V.; Gusev, Anatoly V.

    2009-12-01

    Electron paramagnetic resonance (X-band EPR) spectra are reported for lithium-related donors in monoisotopic silicon. High resolution EPR spectra of lithium donor centers in monoisotopic silicon, enriched by 28Si isotope (99.99%) with very narrow individual lines are observed. In monoisotopic silicon sample (28Si enriched floating zone silicon with low concentration of lithium 1016 cm-3), the trigonal EPR spectrum, with well resolved 7Li hyperfine structure is recorded in the temperature range 3.5-20 K. This spectrum was attributed to LiO complex. At high concentration of lithium (about 1018 cm-3) in monoisotopic silicon two types of spectra are observed. The trigonal one has the same feature as for low concentration of lithium with g-values: g∥=1.9974 and g⊥=1.9989. Another spectrum consists of two lines and has tetragonal symmetry with g∥=1.9992 and g⊥=1.9983. This spectrum is more intensive than the trigonal one and has no resolved hyperfine structure probably due to time averaging of the hyperfine interaction caused by hopping motion of electrons.

  19. Poly[triaquabis(μ2-3-carboxypyrazine-2-carboxylatodilithium(I

    Directory of Open Access Journals (Sweden)

    Orhan Büyükgüngör

    2008-03-01

    Full Text Available In the title compound, [Li2(C6H3N2O42(H2O3]n, the coordination number for both independent Li+ cations is five. One of the Li+ ions has a distorted trigonal–bipyramidal geometry, coordinated by one of the carboxyl O atoms of a 3-carboxypyrazine-2-carboxylate ligand, two O atoms from two water molecules, and an N and a carboxylate O atom of a second 3-carboxypyrazine-2-carboxylate ligand. The other Li+ ion also has a distorted trigonal–bipyramidal geometry, coordinated by one water molecule and two 3-carboxypyrazine-2-carboxylate ligands through an N and a carboxylate O atom from each. One of the carboxyl groups of the two ligands takes part in an intramolecular O—H...O hydrogen bond. The stabilization of the crystal structure is further assisted by O—H...O, O—H...N and C—H...O hydrogen-bonding interactions involving the water molecules and carboxylate O atoms.

  20. Poly[diammonium [diaqua(μ7-benzene-1,2,3,4,5,6-hexacarboxylatotetraoxidodiuranium(VI

    Directory of Open Access Journals (Sweden)

    Paula M. Cantos

    2014-04-01

    Full Text Available Uranyl-carboxylate hybrid materials dominate the catalog of uranyl compounds owing in part to the affinity between COO− functional groups and UO22+. Polycarboxylate organic ligands may present a degree of steric hindrance and could thus influence the resulting uranyl topology. Single crystals of the title compound, {(NH42[(UO22(C12O12(H2O2]}n, were synthesized hydrothermally as a result of reacting uranyl nitrate with benzene-1,2,3,4,5,6-hexacarboxylic acid (mellitic acid. The structure is comprised of a single unique monomeric uranyl cation adopting a pentagonal bipyramidal geometry. The uranyl coordination sphere is composed of four O atoms originating from one half of a fully deprotonated mellitic acid ligand and a single water molecule. The observed axial U—O bonds display an average distance of 1.765 (8 Å, whereas equatorial O atoms are found at an average distance of 2.40 (5 Å. All uranium–oxygen bond lengths are in good agreement with literature values. Furthermore, the coordination between the uranyl pentagonal bipyramids and the mellitic acid anion constructs a three-dimensional anionic framework which is charge-balanced with ammonium cations. Additional stabilization of the structure is provided by O—H...O and N—H...O hydrogen bonding interactions between the components.

  1. Rb2Na(NO33: A Congruently Melting UV-NLO Crystal with a Very Strong Second-Harmonic Generation Response

    Directory of Open Access Journals (Sweden)

    Guohong Zou

    2016-04-01

    Full Text Available Crystals of congruently melting noncentrosymmetric (NCS mixed alkali metal nitrate, Rb2Na(NO33, have been grown through solid state reactions. The material possesses layers with NaO8 hexagonal bipyramids and NO3 triangular units. Rb+ cations are residing in the interlayer space. Each NaO8 hexagonal bipyramid shares its corners and edges with two and three NO3 units, respectively, in order to fulfill a highly dense stacking in the unit cell. The NaO8 groups share their six oxygen atoms in equatorial positions with three different NO3 groups to generate a NaO6-NO3 layer with a parallel alignment. The optimized arrangement of the NO3 groups and their high density in the structure together produce a strong second-harmonic generation (SHG response. Powder SHG measurements indicate that Rb2Na(NO33 has a strong SHG efficiency of five times that of KH2PO4 (KDP and is type I phase-matchable. The calculated average nonlinear optical (NLO susceptibility of Rb2Na(NO33 turns out to be the largest value among the NLO materials composed of only [NO3]− anion. In addition, Rb2Na(NO33 exhibits a wide transparency region ranging from UV to near IR, which suggests that the compound is a promising NLO material.

  2. Synthesis and crystal structure of calcium dizinc iron(III tris(orthophosphate, CaZn2Fe(PO43

    Directory of Open Access Journals (Sweden)

    Jamal Khmiyas

    2016-09-01

    Full Text Available Single crystals of the title compound, CaZn2Fe(PO43, were synthesized by conventional solid-state reaction. In the asymmetric unit, all atoms are located in fully occupied general positions of the P21/c space group. The zinc atoms are located on two crystallographically independent sites with tetrahedral and distorted triangular-based bipyramidal geometries. Two edge-sharing triangular bipyramidal ZnO5 units form a dimer, which is linked to slightly deformed FeO6 octahedra via a common edge. The resulting chains are interconnected through PO4 tetrahedra to form a layer perpendicular to the b axis. Moreover, the remaining PO4 and ZnO4 tetrahedra are linked together through common vertices to form tapes parallel to the c axis and surrounding a chain of Ca2+ cations to build a sheet, also perpendicular to the b axis. The stacking of the two layers along the b axis leads to the resulting three-dimensional framework, which defines channels in which the Ca2+ cations are located, each cation being coordinated by seven oxygen atoms.

  3. One-dimensional inorganic arrangement in the bismuth oxalate hydroxide Bi(C 2O 4)OH

    Science.gov (United States)

    Rivenet, Murielle; Roussel, Pascal; Abraham, Francis

    2008-10-01

    Single crystals of Bi(C 2O 4)OH were obtained by the slow diffusion of Bi 3+ cations through silica gel impregnated with oxalic acid. The structure was solved in the Pnma space group with a=6.0853(2) Å, b=11.4479(3) Å, c=5.9722(2) Å, leading to R=0.0188 and w R=0.0190 from 513 unique reflections. The bismuth coordination polyhedron is a BiO 6E pentagonal bipyramid with the lone pair E sitting at an axial vertex. The opposite axial vertex is occupied by a hydroxyl oxygen atom, which is also an equatorial corner of a neighboring BiO 6E bipyramid. The sharing of the hydroxyl oxygen atoms build ∞1[BiOE] zig-zag chains running down the [100] direction. These chains are aligned in a sheet parallel to the (010) plane and are further connected through oxalate ions to form a three-dimensional arrangement. On heating, Bi(C 2O 4)OH decomposes to the meta-stable quadratic β-Bi 2O 3 phase.

  4. Synthesis and crystal structures of two new tin bis(carboranylamidinate complexes

    Directory of Open Access Journals (Sweden)

    Nicole Harmgarth

    2017-10-01

    Full Text Available Reaction of 2 equiv. of the lithium carboranylamidinate Li[o-(C2H10B10C(NCy(NHCy] with SnCl2 in THF afforded the stannylene compound bis(N,N′-dicyclohexylamidinatocarboranatetin(II, SnII[o-(C2H10B10C(NCy(NHCy]2 (1. A similar reaction of SnCl4 with 2 equiv. of Li[o-(C2H10B10C(NiPr(NHiPr] unexpectedly afforded the known solvated pentachloridostannate(IV salt [Li(THF4][SnCl5(THF] as the main reaction product. Small amounts of the new chlorido-tin(IV bis(carboranylamidinate bis(N,N′-diisopropylamidinatocarboranatechloridotin(IV, SnIVCl[o-(C2H10B10C(NiPr(NHiPr][o-(C2H10B10C(NiPr2] (2, were isolated as a by-product. Single-crystal X-ray structure analysis revealed a κC,κN-chelating coordination of the carboranylamidinate ligands in both 1 and 2. The Sn atom in 1 adopts a pseudo-trigonal–bipyramidal coordination under participation of a stereoactive lone pair. In 2, a trigonal–bipyramidal coordination of Sn is completed by a chlorido ligand.

  5. Highly distorted uranyl ion coordination and one/two-dimensional structural relationship in the Ba2[UO2(TO4)2] (T = P, As) system: an experimental and computational study.

    Science.gov (United States)

    Wu, Shijun; Kowalski, Piotr M; Yu, Na; Malcherek, Thomas; Depmeier, Wulf; Bosbach, Dirk; Wang, Shuao; Suleimanov, Evgeny V; Albrecht-Schmitt, Thomas E; Alekseev, Evgeny V

    2014-07-21

    Uranium compounds α-Ba2[UO2(PO4)2] (1), β-Ba2[UO2(PO4)2] (2), and Ba2[UO2(AsO4)2] (3) were synthesized by H3BO3/B2O3 flux reactions, though boron is not incorporated into the structures. Phases 1 and 2 are topologically identical, but 1 is heavily distorted with respect to 2. An unusual UO7 pentagonal bipyramid occurs in 1, exhibiting a highly distorted equatorial configuration and significant bending of the uranyl group, due to edge-sharing with one neighboring PO4(3-) tetrahedron. Compound 2 contains more normal square bipyramids that share corners with four neighboring PO4(3-) tetrahedra, but the uranyl cation UO2(2+) is tilted relative to the equatorial plane. Experimental evidence as well as density functional theory (DFT) calculations suggest that 1 is more stable than 2. In theory, 1 and 2 can interconvert by forming/releasing the shared edge between the uranyl polyhedron and the phosphate tetrahedron. Similar fundamental building blocks in β-Ba2[UO2(PO4)2] and Ba2[UO2(AsO4)2] indicate a possible evolution of uranyl-based structures from chain to layer type and formation of an accretional series.

  6. Phonon-Driven Oscillatory Plasmonic Excitonic Nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Kirschner, Matthew S. [Department; Ding, Wendu [Department; Li, Yuxiu [Center; College; Chapman, Craig T. [Department; Lei, Aiwen [College; Lin, Xiao-Min [Center; Chen, Lin X. [Department; Chemical; Schatz, George C. [Department; Schaller, Richard D. [Department; Center

    2017-12-08

    We demonstrate that coherent acoustic phonons derived from plasmonic nanoparticles can modulate electronic interactions with proximal excitonic molecular species. A series of gold bipyramids with systematically varied aspect ratios and corresponding localized surface plasmon resonance energies, functionalized with a J-aggregated thiacarbocyanine dye molecule, produce two hybridized states that exhibit clear anti-crossing behavior with a Rabi splitting energy of 120 meV. In metal nanoparticles, photoexcitation generates coherent acoustic phonons that cause oscillations in the plasmon resonance energy. In the coupled system, these photo-generated oscillations alter the metal nanoparticle’s energetic contribution to the hybridized system and, as a result, change the coupling between the plasmon and exciton. We demonstrate that such modulations in the hybridization is consistent across a wide range of bipyramid ensembles. We also use Finite-Difference Time Domain calculations to develop a simple model describing this behavior. Such oscillatory plasmonic-excitonic nanomaterials (OPENs) offer a route to manipulate and dynamically-tune the interactions of plasmonic/excitonic systems and unlock a range of potential applications.

  7. Geometrical Structures of Partially Oxidized Rhodium Cluster Cations, Rh6Om(+) (m = 4, 5, 6), Revealed by Infrared Multiple Photon Dissociation Spectroscopy.

    Science.gov (United States)

    Koyama, Kohei; Nagata, Toshiaki; Kudoh, Satoshi; Miyajima, Ken; Huitema, Douwe M M; Chernyy, Valeriy; Bakker, Joost M; Mafuné, Fumitaka

    2016-11-03

    Infrared multiple photon dissociation (IRMPD) spectra of Rh6Om(+) (m = 4-10) are obtained in the 300-1000 cm(-1) spectral range using the free electron laser for infrared experiments (FELIX) via dissociation of Rh6Om(+) or Rh6Om(+)-Ar complexes. The spectra are compared with the calculated spectra of several stable geometries obtained by density functional theory (DFT) structural optimization. The spectrum for Rh6O4(+) shows prominent bands at 620 and 690 cm(-1) and is assigned to a capped-square pyramidal Rh atom geometry with three bridging O atoms and one O atom in a hollow site. Rh6O5(+) displays bands at 460, 630, 690, and 860 cm(-1) and has a prismatic Rh geometry with three bridging O atoms and two O atoms in a hollow site. Rh6O6(+) shows three intense bands around 600-750 cm(-1) and multiple weak bands in the range of 350-550 cm(-1). This species has a prismatic Rh geometry with four bridging O atoms and two O atoms in a hollow site. Considering that Rh6Om(+) (m ≤ 3) adopts tetragonal bipyramidal Rh6 structures, the change at m = 4 to capped bipyramidal and at m = 5 to prismatic geometries results in a reduction of the number of triangular hollow sites. Since NO preferentially binds on a triangular hollow site through the N atom, the geometry change lowers the possibility of NO dissociative adsorption.

  8. Structural and dynamical properties of liquid Cu[subscript 80]Si[subscript 20] alloy studied experimentally and by ab initio molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Wu, S.; Kramer, M.J.; Fang, X.W.; Wang, S.Y.; Wang, C.Z.; Ho, K.M.; Ding, Z.J.; Chen, L.Y. (Ames); (UST - China); (Fudan)

    2012-02-06

    The local structures and dynamical properties of the liquid Cu{sub 80}Si{sub 20} alloy have been studied by x-ray diffraction and ab initio molecular dynamics (MD) simulations. The pair-correlation functions and the structure factors derived from the three-dimensional coordinates of the MD configurations agree well with the experimental results. The local structure of the liquids is analyzed using Honeycutt-Andersen (HA) indices, Voronoi tessellation (VT), and an atomic cluster-alignment method. The HA indices analysis shows that the pentagonal bipyramid, a fragment of an icosahedron (ICO), plays a dominant role in the short-range order (SRO) of the Cu{sub 80}Si{sub 20} liquid. The HA indices corresponding to the pentagonal bipyramid increase dramatically with decreasing temperature. VT analysis indicates that, while the liquid does exhibit a strong icosahedral SRO, fcc-like SRO is also measurable. The results from VT analysis are further confirmed using the recently developed atomic cluster-alignment method. Finally, self-diffusion constants, as a function of temperature for both Cu and Si species, are calculated.

  9. K(MoO24O3(AsO4

    Directory of Open Access Journals (Sweden)

    Raja Jouini

    2013-06-01

    Full Text Available A new compound with a non-centrosymmetric structure, potassium tetrakis[dioxomolybdenum(IV] arsenate trioxide, K(MoO24O3(AsO4, has been synthesized by a solid-state reaction. The [(MoO24O3(AsO4]+ three-dimensional framework consists of single arsenate AsO4 tetrahedra, MoO6 octahedra, MoO5 bipyramids and bioctahedral units of edge-sharing Mo2O10 octahedra. The [Mo2O8]∞ octahedral chains running along the a-axis direction are connected through their corners to the AsO4 tetrahedra, MoO6 octahedra and MoO5 bipyramids, so as to form large tunnels propagating along the a axis in which the K+ cations are located. This structure is compared with compounds containing M2O10 (M = Mo, V, Fe dimers and with those containing M2O8 (M = V chains.

  10. Moessbauer spectroscopy in neptunium compounds

    Energy Technology Data Exchange (ETDEWEB)

    Nakamoto, Tadahiro; Nakada, Masami; Masaki, Nobuyuki; Saeki, Masakatsu [Japan Atomic Energy Research Inst., Tokyo (Japan)

    1997-03-01

    Moessbauer effects are observable in seven elements of actinides from {sup 232}Th to {sup 247}Cm and Moesbauer spectra have been investigated mainly with {sup 237}Np and {sup 238}U for the reasons of availability and cost of materials. This report describes the fundamental characteristics of Moessbauer spectra of {sup 237}Np and the correlation between the isomer shift and the coordination number of Np(V) compounds. The isomer shifts of Np(V) compounds had a tendency to increase as an increase of coordination number and the isomer shifts of Np(V) compounds showed broad distribution as well as those of Np(VI) but {delta} values of the compounds with the same coordination number were distributed in a narrow range. The {delta} values of Np(VI) complexes with O{sub x} donor set suggest that the Np atom in its hydroxide (NpO{sub 2}(OH){center_dot}4H{sub 2}O)might have pentagonal bipyramidal structure and at least, pentagonal and hexagonal bipyramidal structures might coexist in its acetate and benzoate. Really, such coexistence has been demonstrated in its nitrate, (NpO{sub 2}){sub 2}(NO{sub 3}){sub 2}{center_dot}5H{sub 2}O. (M.N.)

  11. Lattice-Matched Semiconductor Layers on Single Crystalline Sapphire Substrate

    Science.gov (United States)

    Choi, Sang; King, Glen; Park, Yeonjoon

    2009-01-01

    SiGe is an important semiconductor alloy for high-speed field effect transistors (FETs), high-temperature thermoelectric devices, photovoltaic solar cells, and photon detectors. The growth of SiGe layer is difficult because SiGe alloys have different lattice constants from those of the common Si wafers, which leads to a high density of defects, including dislocations, micro-twins, cracks, and delaminations. This innovation utilizes newly developed rhombohedral epitaxy of cubic semiconductors on trigonal substrates in order to solve the lattice mismatch problem of SiGe by using trigonal single crystals like sapphire (Al2O3) as substrate to give a unique growth-orientation to the SiGe layer, which is automatically controlled at the interface upon sapphire (0001). This technology is different from previous silicon on insulator (SOI) or SGOI (SiGe on insulator) technologies that use amorphous SiO2 as the growth plane. A cubic semiconductor crystal is a special case of a rhombohedron with the inter-planar angle, alpha = 90 deg. With a mathematical transformation, all rhombohedrons can be described by trigonal crystal lattice structures. Therefore, all cubic lattice constants and crystal planes (hkl) s can be transformed into those of trigonal crystal parameters. These unique alignments enable a new opportunity of perfect lattice matching conditions, which can eliminate misfit dislocations. Previously, these atomic alignments were thought to be impossible or very difficult. With the invention of a new x-ray diffraction measurement method here, growth of cubic semiconductors on trigonal crystals became possible. This epitaxy and lattice-matching condition can be applied not only to SiGe (111)/sapphire (0001) substrate relations, but also to other crystal structures and other materials, including similar crystal structures which have pointgroup rotational symmetries by 120 because the cubic (111) direction has 120 rotational symmetry. The use of slightly miscut (less than

  12. A structure-based analysis of the vibrational spectra of nitrosyl ligands in transition-metal coordination complexes and clusters

    Science.gov (United States)

    De La Cruz, Carlos; Sheppard, Norman

    2011-01-01

    . Environmental differences to these values, e.g. data taken in polar solutions or in the crystalline state, can cause ν(NO)* variations (mostly reductions) of up to ca. 30 cm -1. Three spectroscopic criteria are used to distinguish between linear and bent NO groups. These are: (i) the values of ν( 14NO) themselves, and (ii) the isotopic band shift - (IBS) - parameter which is defined as [ν( 14NO)-ν( 15NO)], and, (iii) the isotopic band ratio - (IBR) - given by [ν( 15NO/ν 14NO)]. The former is illustrated with the ν( 14NO)-data from trigonal bipyramidal (TBP) and tetragonal pyramidal (TP) structures of [M(NO(L) 4] complexes (where M = Fe, Co, Ru, Rh, Os, Ir and L = ligand). These values indicate that linear (180-170°) and strongly bent (130-120°) NO groups in these compounds absorb over the 1862-1690 cm -1 and 1720-1525 cm -1-regions, respectively. As was explicitly demonstrated for the linear nitrosyls, these extensive regions reflect the presence in different complexes of a very wide range of co-ligands or ionic charges associated with the metal atom of the nitrosyl group. A plot of the IBS parameter against M-N-O bond-angle for compounds with general formulae [M(NO)(L) y] ( y = 4, 5, 6) reveals that the IBS-values are clustered between 45 and 30 cm -1 or between 37 and 25 cm -1 for linear or bent NO groups, respectively. A plot of IBR shows a less well defined pattern. Overall it is suggested that bent nitrosyls absorb ca. 60-100 cm -1 below, and have smaller co-ligand band-shifts, than their linear counterparts. Spectroscopic ν(NO) data of the bridging or other types of NO ligands are comparatively few and therefore it has not been possible to give other than general ranges for 'neutral co-ligand' values. Moreover the bridging species data often depend on corrections for the effects of electronically-active co-ligands such as cyclopentadienyl-like groups. The derived neutral co-ligand estimates, ν(NO)*, are: (a) twofold bridged nitrosyls with a metal-metal bond

  13. Metal ion displacements in noncentrosymmetric chalcogenides La3Ga1.67S7, La3Ag0.6GaCh7 (Ch=S, Se), and La3MGaSe7 (M=Zn, Cd)

    Science.gov (United States)

    Iyer, Abishek K.; Yin, Wenlong; Rudyk, Brent W.; Lin, Xinsong; Nilges, Tom; Mar, Arthur

    2016-11-01

    The quaternary Ga-containing chalcogenides La3Ag0.6GaS7, La3Ag0.6GaSe7, La3ZnGaSe7, and La3CdGaSe7, as well as the related ternary chalcogenide La3Ga1.67S7, were prepared by reactions of the elements at 950 °C. They adopt noncentrosymmetric hexagonal structures (space group P63, Z=2) with cell parameters (a=10.2 Å, c=6.1 Å for the sulfides; a=10.6 Å, c=6.4 Å for the selenides) that are largely controlled by the geometrical requirements of one-dimensional stacks of Ga-centered tetrahedra separated by the La atoms. Among these compounds, which share the common formulation La3M1-xGaCh7 (M=Ga, Ag, Zn, Cd; Ch=S, Se), the M atoms occupy sites within a stacking of trigonal antiprisms formed by Ch atoms. The location of the M site varies between extremes with trigonal antiprismatic (CN6) and trigonal planar (CN3) geometry. Partial occupation of these sites and intermediate ones accounts for the considerable versatility of these structures and the occurrence of large metal displacement parameters. The site occupations can be understood in a simple way as being driven by the need to satisfy appropriate bond valence sums for both the M and Ch atoms. Band structure calculations rationalize the substoichiometry observed in the Ag-containing compounds (La3Ag0.6GaS7, La3Ag0.6GaSe7) as a response to overbonding. X-ray photoelectron spectroscopy supports the presence of monovalent Ag atoms in these compounds, which are not charge-balanced.

  14. Anterior and posterior compartment 3D endovaginal ultrasound anatomy based on direct histologic comparison.

    Science.gov (United States)

    Shobeiri, S Abbas; White, Dena; Quiroz, Lieschen H; Nihira, Mikio A

    2012-08-01

    We used direct histologic comparison to validate the use of 3D endovaginal ultrasound (EVUS) as a novel and emerging technology for evaluating the structures found in the anterior and posterior pelvic floor compartments. A young nulliparous female pelvis specimen was dissected and histologic slides were prepared by making 8-Micron-thick sagittal cuts. The slides were stained with Mallory trichrome and arranged to form large sections encompassing each anterior and posterior sagittal plane. Healthy nulliparous women underwent 3D EVUS to obtain 3D cubes of the anterior and posterior compartments. Two investigators independently evaluated the anterior and posterior midsagittal structures. The investigators mutually viewed the images and calculated urethral and anal sphincter measurements. Thirty-one nulliparous women underwent 3D EVUS; 77% of the participants were Caucasian, with mean age 31.8 [standard deviation (SD) 5.8] and mean body mass index (BMI) of 28.5 (SD 7.9). The following mean (SD) measurements were obtained: urethral length 36 mm (± 5); striated urogenital sphincter area 0.6 cm(2) (± 0.16); longitudinal and circular smooth muscle area 1.1 cm(2) (± 0.4); urethral complex width 14 mm (± 2); urethral complex area 1.3 cm(2) (± 0.4); internal anal sphincter length 26 mm (± 4); internal anal sphincter thickness 3.2 mm (± 0.8); and rectovaginal septum length 31 mm (± 5). The agreement for visualization of structures was as follows: vesical trigone 96% (κ = 0.65), trigonal ring 94% (κ = 0.8), trigonal plate 84% (κ = 0.6); longitudinal and circular smooth muscle 100%; compressor urethra 97% (κ = 0.85); striated urogenital sphincter 97% (κ = 0.85); rectovaginal septum 100%; internal anal sphincter 100%; external anal sphincter subdivisions 100%. Three-dimensional EVUS can be used to visualize structures of the anterior and posterior compartments in nullipara.

  15. Size and placement of developing anterior teeth in immature Neanderthal mandibles from Dederiyeh Cave, Syria: implications for emergence of the modern human chin.

    Science.gov (United States)

    Fukase, Hitoshi; Kondo, Osamu; Ishida, Hajime

    2015-03-01

    Evolutionary and functional significance of the human chin has long been explored from various perspectives including masticatory biomechanics, speech, and anterior tooth size. Recent ontogenetic studies have indicated that the spatial position of internally forming anterior teeth partially constrains adult mandibular symphyseal morphology. The present study therefore preliminarily examined the size and placement of developing anterior teeth in immature Neanderthal mandibles of Dederiyeh 1 and 2, compared with similarly-aged modern humans (N = 16) and chimpanzees (N = 7) whose incisors are comparatively small and large among extant hominids, respectively. The Dederiyeh 1 mandible is described as slightly presenting a mental trigone and attendant mental fossa, whereas Dederiyeh 2 completely lacks such chin-associated configurations. Results showed that, despite symphyseal size being within the modern human range, both Dederiyeh mandibles accommodated overall larger anterior dentition and displayed a remarkably wide bicanine space compared to those of modern humans. Dederiyeh 2 had comparatively thicker deciduous incisor roots and more enlarged permanent incisor crypts than Dederiyeh 1, but both Dederiyeh individuals exhibited a total dental size mostly intermediate between modern humans and chimpanzees. These findings potentially imply that the large deciduous/permanent incisors collectively distended the labial alveolar bone, obscuring an incipient mental trigone. It is therefore hypothesized that the appearance of chin-associated features, particularly of the mental trigone and fossa, can be accounted for partly by developmental relationships between the sizes of the available mandibular space and anterior teeth. This hypothesis must be, however, further addressed with more referential samples in future studies. © 2014 Wiley Periodicals, Inc.

  16. SU-E-T-356: Accuracy of Eclipse Electron Macro Monte Carlo Dose Algorithm for Use in Bolus Electron Conformal Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Carver, R [Mary Bird Perkins Cancer Center, Baton Rouge, LA (United States); Popple, R; Benhabib, S [UniversityAlabama Birmingham, Birmingham, AL (United Kingdom); Antolak, J [Mayo Clinic, Rochester, MN (United States); Sprunger, C [Louisiana State University, Baton Rouge, LA (United States); Hogstrom, K [Mary Bird Perkins Cancer Center, Baton Rouge, LA (United States); Louisiana State University, Baton Rouge, LA (United States)

    2014-06-01

    Purpose: To evaluate the accuracy of electron dose distribution calculated by the Varian Eclipse electron Monte Carlo (eMC) algorithm for use with recent commercially available bolus electron conformal therapy (ECT). Methods: eMC-calculated electron dose distributions for bolus ECT have been compared to those previously measured for cylindrical phantoms (retromolar trigone and nose), whose axial cross sections were based on the mid-PTV CT anatomy for each site. The phantoms consisted of SR4 muscle substitute, SR4 bone substitute, and air. The bolus ECT treatment plans were imported into the Eclipse treatment planning system and calculated using the maximum allowable histories (2×10{sup 9}), resulting in a statistical error of <0.2%. Smoothing was not used for these calculations. Differences between eMC-calculated and measured dose distributions were evaluated in terms of absolute dose difference as well as distance to agreement (DTA). Results: Results from the eMC for the retromolar trigone phantom showed 89% (41/46) of dose points within 3% dose difference or 3 mm DTA. There was an average dose difference of −0.12% with a standard deviation of 2.56%. Results for the nose phantom showed 95% (54/57) of dose points within 3% dose difference or 3 mm DTA. There was an average dose difference of 1.12% with a standard deviation of 3.03%. Dose calculation times for the retromolar trigone and nose treatment plans were 15 min and 22 min, respectively, using 16 processors (Intel Xeon E5-2690, 2.9 GHz) on a Varian Eclipse framework agent server (FAS). Results of this study were consistent with those previously reported for accuracy of the eMC electron dose algorithm and for the .decimal, Inc. pencil beam redefinition algorithm used to plan the bolus. Conclusion: These results show that the accuracy of the Eclipse eMC algorithm is suitable for clinical implementation of bolus ECT.

  17. Bis(μ-2-methyl-8-oxidoquinolin-1-ium-κ2O:Obis[(acetato-κ2O,O′(2-methyl-8-oxidoquinolin-1-ium-κObis(nitrato-κ2O,O′lanthanum(III

    Directory of Open Access Journals (Sweden)

    Yousef Fazaeli

    2010-02-01

    Full Text Available The N-heterocycles in the centrosymmetric title compound, [La2(C10H9NO4(CH3COO2(NO34], exist in the zwitterionic form. One heterocycle binds to a metal center whereas the other bridges two metal centers. Each La atom is chelated by an acetate and two nitrate groups and is surrounded by nine O atoms in a distorted tricapped trigonal-prismatic coordination environment. The N—H groups form intramolecular N—H...O hydrogen bonds. One of the nitrate ions is disordered over two positions in a 0.80 (3:0.20 (3 occupancy ratio.

  18. Appearance of singularities of optical fields under torsion of crystals containing threefold symmetry axes.

    Science.gov (United States)

    Skab, Ihor; Vasylkiv, Yurij; Zapeka, Bohdan; Savaryn, Viktoriya; Vlokh, Rostyslav

    2011-07-01

    We present an analysis of the effect of torsion stresses on the spatial distribution of optical birefringence in crystals of different point symmetry groups. The symmetry requirements needed so that the optical beam carries dislocations of the phase front are evaluated for the case when the crystals are twisted and the beam closely corresponds to a plane wave. It is shown that the torsion stresses can produce screw-edge, pure screw, or pure edge dislocations of the phase front in the crystals belonging to cubic and trigonal systems. The conditions for appearance of canonical and noncanonical vortices in the conditions of crystal torsion are analyzed. © 2011 Optical Society of America

  19. Infinitesimal base transformations method for calculating the k.p Hamiltonian of monolayer MoS2

    Science.gov (United States)

    Beiranvand, Khadijeh; Ghalambor Dezfuli, Abdolmohammad; Sabaeian, Mohammad

    2017-10-01

    In this work, we present the study of monolayer MoS2 band structure using k.p method based on infinitesimal basis transformations perturbation theory. We also study the effect of spin-orbit coupling on the band structure. We have calculated the low energy k.p Hamiltonian and derived the dispersion relations for the last valance band and the first conduction band at K and -K points of the first Brillouin zone. The results clearly show the electron-hole asymmetry and trigonal warping effects. The results also indicate the spin-splitting of the first conduction band.

  20. Tetrakis[μ-2-(3,4-dimethoxyphenylacetato]-κ4O:O′;κ3O,O′:O;κ3O:O,O′-bis{[2-(3,4-dimethoxyphenylacetato-κ2O,O′](1,10-phenanthroline-κ2N,N′samarium(III}

    Directory of Open Access Journals (Sweden)

    Jia-Lu Liu

    2010-11-01

    Full Text Available In the centrosymmetric dinuclear title complex, [Sm2(C10H11O46(C12H8N22], the SmIII ion is nine-coordinated by seven O atoms of five 2-(3,4-dimethoxyphenylacetate (DMPA ligands and two N atoms of one bis-chelating 1,10-phenanthroline (phen ligand, forming a distorted tricapped trigonal-prismatic environment. The DMPA ligands coordinate in bis-chelate, bridging and bridging tridentate modes. An intramolecular C—H...O hydrogen bond occurs. Intermolecular C—H...O interactions are also present in the crystal.

  1. Magnetic Properties of 3D Heptanuclear Lanthanide Frameworks Supported by Mixed Ligands.

    Science.gov (United States)

    Hu, Fa-Lu; Jiang, Fei-Long; Zheng, Jun; Wu, Ming-Yan; Pang, Jian-Dong; Hong, Mao-Chun

    2015-07-06

    Two 3D lanthanide frameworks, [Ln7(DPA)5(NA)3(μ3-OH)8(H2O)3]·2.5H2O [H2DPA = diphenic acid; HNA = nicotinic acid; Ln = Gd (1), Dy (2)], were synthesized and structurally characterized. They were rarely seen examples of 3D frameworks constructed from heptanuclear trigonal-antiprismatic lanthanide clusters with mixed H2DPA and HNA ligands. Both 1 and 2 show typical antiferromagnetic interactions. Additionally, complex 1 possesses a large magnetocaloric effect of 34.15 J kg(-1) K(-1).

  2. Poly[[aqua-?3-picolinato-?2-picolinato-dipicolinatopotassium(I)terbium(III)] 2.5-hydrate

    OpenAIRE

    Filipe A. Almeida Paz; João Rocha; Jacek Klinowski; Tito Trindade; Nogueira,Helena I. S.; Soares-Santos, Paula C. R.; Cunha-Silva, Lu?s

    2008-01-01

    In the title compound, [KTb(C6H4NO2)4(H2O)]·2.5H2O, each Tb3+ centre is coordinated by four N and five O atoms from five distinct picolinate ligands in a geometry resembling a highly distorted tricapped trigonal prism. One of the ligands establishes a skew bridge between neighbouring Tb3+ centres, leading to the formation of one-dimensional anionic polymeric chains, {[(C6H4NO2)4Tb]−}n, running along the direction [010]. Each K+ cation is seven-coordinated by six O atoms from one an...

  3. (2,2′-Bipyridylbis[N,N-bis(2-hydroxyethyldithiocarbamato-κ2S,S′]cadmium(II

    Directory of Open Access Journals (Sweden)

    Edward R. T. Tiekink

    2009-12-01

    Full Text Available The title compound, [Cd(C5H10NO2S22(C10H8N2], features a trigonal-prismatic coordination geometry for the CdII ion, based on an N2S4 donor set defined by two chelating dithiocarbamate ligands and a 2,2′-bipyridyl ligand. In the crystal, extensive O—H...O hydrogen bonding results in the formation of 12-membered {...HO}6 synthons and one-dimensional supramolecular chains with further O—H...S interactions providing additional stability to the linear chain with base vector [01overline{1}].

  4. Preferred orientation of ettringite in concrete fractures

    KAUST Repository

    Wenk, Hans-Rudolf

    2009-05-15

    Sulfate attack and the accompanying crystallization of fibrous ettringite [Ca6Al2(OH)12(SO4) 3·26H2O] cause cracking and loss of strength in concrete structures. Hard synchrotron X-ray microdiffraction is used to quantify the orientation distribution of ettringite crystals. Diffraction images are analyzed using the Rietveld method to obtain information on textures. The analysis reveals that the c axes of the trigonal crystallites are preferentially oriented perpendicular to the fracture surfaces. By averaging single-crystal elastic properties over the orientation distribution, it is possible to estimate the elastic anisotropy of ettringite aggregates. © 2009 International Union of Crystallography.

  5. Growth and characterization of Pb{sub 3}Ni{sub 1.5}Mn{sub 5.5}O{sub 15} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Milenov, T I; Rafailov, P M; Tomov, V; Gospodinov, M M [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Boulevard, 1784 Sofia (Bulgaria); Nikolova, R P [Central Laboratory of Mineralogy and Crystallography, Bulgarian Academy of Sciences, 107 Academician G Bonchev Street, Sofia 1113 (Bulgaria); Skumryev, V [Institucio Catalana de Recerca i Estudis Avancats (ICREA) and Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Igartua, J M; Madariaga, G [Departamento Fisica de la Materia Condensada, Facultad Ciencia y TecnologIa, UPV/EHU, PO 644, 48080 Bilbao (Spain); Lopez, G A [MicroscopIa Electronica y Microanalisis de Materiales, SGIKer, UPV/EHU, Bilbao (Spain); Iturbe-Zabalo, E, E-mail: teddy@issp.bas.bg [Institut Laue-Langevin (ILL), 6 rue Jules Horowitz, BP156, 38042 Grenoble Cedex 9 (France)

    2011-04-20

    Single crystals of the mixed valence compound Pb{sub 3}Ni{sub 1.5}Mn{sub 5.5}O{sub 15} were successfully grown. Polarized Raman spectroscopy revealed that they belong to the point group D{sub 3d}, in accordance with single-crystal x-ray diffraction data which were refined within the trigonal space group P3barc1 (No. 165), with lattice parameters a = 9.941(3) A and c = 13.543(3) A. Strongly anisotropic long range magnetic order is established below 65 K.

  6. Mo{sub 6}S{sub 4.5}I{sub 4.5} Nanowires: Structure Studies by HRTEM and Aberration Corrected STEM

    Energy Technology Data Exchange (ETDEWEB)

    Nicolosi, Valeria [University of Dublin - Trinity College, Department of Physics, Dublin 2 (Ireland); Nellist, Peter [University of Dublin - Trinity College, Department of Physics, Dublin 2 (Ireland); Sloan, Jeremy [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QR (United Kingdom); Mihailovic, Dragan [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Mo6, Teslova 30, 1000 Ljubljana (Slovenia); Green, Malcom [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QR (United Kingdom); Blau, Werner J [University of Dublin - Trinity College, Department of Physics, Dublin 2 (Ireland); Coleman, Jonathan N [University of Dublin - Trinity College, Department of Physics, Dublin 2 (Ireland)

    2006-02-22

    The atomic structure of subnanometer diameter Mo{sub 6}S{sub 4.5}I{sub 4.5} nanowires and their superlattice packing in bundles have been studied by High Resolution Transmission Electron Microscopy (HRTEM) and Aberration Corrected Scanning Transmission Electron Microscopy (STEM). The individual nanowires are best described as one-dimensional Mo-chalcogenidehalide cluster polymers, composed of Mo octahedra, surrounded by iodine atoms and connected by bridging planes of 3 sulfur atoms. The nanowires are weakly bounded together into bundles by Van der Waals forces in a trigonal packing arrangement, with a nanowire to nanowire distance of 0.96 nm.

  7. Фазовый состав керамики Al[2]O[3]-ZrW[2]O[8

    OpenAIRE

    Ханзина, Н.; Ветрова, А. В.; Дедова, Елена Сергеевна; Кульков, Сергей Николаевич

    2016-01-01

    In the course of work the phase composition of the ceramic composite material Al[2]O[3] - 50 % ZrW[2]O[8] was studied. On the polished surface of the Al[2]O[3]-ZrW[2]O[8] sintered composite can be allocated three areas: dark gray matrix, white inclusions of an irregular form and spherical inclusions. The average size of spherical inclusions was equal to 15 [mu]m. The phase structure of ceramic composite was presented by trigonal modification of aluminum oxide, cubic zirconium tungstate, monoc...

  8. Complete elastic constants of α−BaB{sub 2}O{sub 4}: Resonant ultrasound spectroscopy versus Schaefer-Bergmann diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, Jonathan B.; Kaufman, Yaniv; Wagner, Kelvin H. [Dept. of Electrical and Computer Engineering, University of Colorado, Boulder, CO (United States); Ledbetter, Hassel [Dept. of Mechanical Engineering, University of Colorado, Boulder, CO (United States)

    2014-05-27

    We utilized both resonant ultrasound spectroscopy (RUS) and Schaefer-Bergmann diffraction patterns (SBDP) to measure the elastic stiffness coefficients of the trigonal, non-piezo-electric crystal α−BaB{sub 2}O{sub 4}. RUS determines the elastic coefficients of a sample by matching measured resonant frequencies to a model of resonances. SBDP deduces the elastic coefficients by fitting the measured shape of the acousto-optic diffraction pattern to an acoustic slowness surface cross-section. We present our measured elastic coefficients of α−BaB{sub 2}O{sub 4} from both RUS and SBDP experiments.

  9. Two-step crystal engineering of porous nets from [Cr3(μ 3-O)(RCO2)6] and [Cu3(μ 3-Cl)(RNH2)6Cl6] molecular building blocks

    KAUST Repository

    Elsaidi, Sameh K.

    2013-01-01

    Two porous nets have been prepared via a 2-step crystal engineering approach that links decorated trigonal prismatic [Cr3(μ 3-O)(CO2)6] and [Cu3(μ 3-Cl)(RNH2)6Cl6] molecular building blocks, MBBs. tp-PMBB-5-acs-1 is a rare example of a rigid acs underlying net whereas tp-PMBB-6-stp-1, an stp underlying net, exhibits free NH2 groups in its channels and a relatively high isosteric heat of adsorption for CO2. © 2013 The Royal Society of Chemistry.

  10. CaSeO4-0.625H2O - Water Channel Occupation in a bassanite Related Structure

    Energy Technology Data Exchange (ETDEWEB)

    S Fritz; H Schmidt; I Paschke; O Magdysyuk; R Dinnebier; D Freyer; W Voigt

    2011-12-31

    Calcium selenate subhydrate, CaSeO{sub 4} {center_dot} 0.625H{sub 2}O, was prepared by hydrothermal conversion of CaSeO{sub 4} {center_dot} 2H{sub 2}O at 463 K. From the single crystals obtained in the shape of hexagonal needles, 50-300 {micro}m in length, the crystal structure could be solved in a trigonal unit cell with space group P3{sub 2}21. The cell was confirmed and refined by high-resolution synchrotron powder diffraction. The subhydrate was characterized by thermal analysis and Raman spectroscopy.

  11. The loss of magnetism in FeS under high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Ropka, Z. [Center for Solid State Physics, Krakow (Poland); Radwanski, R.J. [Center for Solid State Physics, Krakow (Poland); Institute of Physics, Pedagogical University, 30-084 Krakow (Poland)

    2003-03-01

    It is argued that the formation of the non-magnetic state of FeS in external pressures above 6.5 GPa is in agreement with the prediction of the many-electron crystal-field theory with the spin-orbit coupling incorporated, and is related to the change of sign of the off-octahedral trigonal distortion marked by the dramatic change of the c/a ratio from larger than 1.63 in the low-pressure magnetic state to smaller than 1.63 in the high-pressure non-magnetic state. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  12. Influence of anisotropy on thermal boundary conductance at solid interfaces

    Science.gov (United States)

    Hopkins, Patrick E.; Beechem, Thomas; Duda, John C.; Hattar, Khalid; Ihlefeld, Jon F.; Rodriguez, Mark A.; Piekos, Edward S.

    2011-09-01

    We investigate the role of anisotropy on interfacial transport across solid interfaces by measuring the thermal boundary conductance from 100 to 500 K across Al/Si and Al/sapphire interfaces with different substrate orientations. The measured thermal boundary conductances show a dependency on substrate crystallographic orientation in the sapphire samples (trigonal conventional cell) but not in the silicon samples (diamond cubic conventional cell). The change in interface conductance in the sapphire samples is ascribed to anisotropy in the Brillouin zone along the principal directions defining the conventional cell. This leads to resultant phonon velocities in the direction of thermal transport that vary nearly 40% based on crystallographic direction.

  13. Cholesterol monohydrate nucleation in ultrathin films on water

    DEFF Research Database (Denmark)

    Rapaport, H.; Kuzmenko, I.; Lafont, S.

    2001-01-01

    The growth of a cholesterol crystalline phase, three molecular layers thick at the air-water interface, was monitored by grazing incidence x-ray diffraction and x-ray reflectivity. Upon compression, a cholesterol film transforms from a monolayer of trigonal symmetry and low crystallinity...... to the triclinic 3-D crystal structure of cholesterol . H(2)O. By comparison, the cholesterol derivative stigmasterol transforms, upon compression, directly into a crystalline trilayer in the rectangular lattice. These results may contribute to an understanding of the onset of cholesterol crystallization...

  14. Kui seda mammit seal jalus ei oleks... / Indrek Pajo, Heiti Riisberg, Jaana Liigand... [jt.

    Index Scriptorium Estoniae

    2010-01-01

    Küsimusele, mida peaks noor keskjuht juhtimise osas tegema kui tunneb pärast paarikuist töötamist üha rohkem, et mõned tema alluvad, kes on temast oluliselt vanemad, töötavad talle vastu, vastavad endine Cleaner Ehitus vanemobjektijuht Indrek Pajo, Trigon Kapital pensioni- ja aktsiafondide eest hoolitsev Heiti Riisberg, konsultatsioonifirma Arikano omanik ja juht Jaana Liigand, Pharmadule OÜ personali- ja büroojuht Helen Neeve, Saku Õlletehase brändide Rock ja Carlsberg juht Karin Golubev ning Kaamos Kinnisvara juht Priit Uustulnd

  15. Electron-electron Interactions in ABC-stacked Multilayer Graphene

    Science.gov (United States)

    Zhang, Fan; MacDonald, Allan

    2010-03-01

    The electronic band structures of ABC-stacked multilayer graphene systems are obtained by the tight-binding calculation and the density function theory. We predict that the electron- electron interactions drive the neutral graphene multilayer systems to pseudospin magnets in which the charge density contribution spontaneously shifts to either the top or the bottom layers, based on the HF and PRG calculations. We show that the spin and valley degrees of freedom enhance the instabilities. We investigate the influence on the broken symmetry phase by the trigonal warping, the external electric field and the number of coupled graphene layers.

  16. Structure and Gas-Phase Thermochemistry of a Pd/Cu Complex: Studies on a Model for Transmetalation Transition States.

    Science.gov (United States)

    Oeschger, Raphael J; Chen, Peter

    2017-01-25

    A heterobimetallic Pd(II)/Cu(I) complex was prepared and characterized by X-ray diffraction analysis. The crystal structure shows a remarkably short Pd-Cu bond and a trigonal ipso carbon atom. The Pd-Cu interaction, as determined by energy-resolved collision-induced dissociation cross-section experiments, models the net stabilizing energy of the Pd-Cu interaction in the transition state of the transmetalation step in Pd/Cu-catalyzed cross-coupling reactions. The bonding situation in the bimetallic dinuclear complex has been studied by atoms-in-molecules analysis.

  17. Crystal structure of [2,6-bis(adamantan-1-yl-4-tert-butylphenolato-κO]dimethylaluminium(III

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2014-10-01

    Full Text Available The title compound, [Al(CH32(C30H41O] is synthesized by the reaction of 2,6-di-adamantyl-4-tert-butyl-phenol with Al(CH33 in a nitrogen atmosphere. In the molecule, the coordination geometry around the AlIII atom is slightly distorted C2O trigonal (the sum of the bond angles subtended at Al atom being 359.9°, which is rarely reported for organometallic aluminium compounds. The coordination plane is approximately perpendicular to the benzene ring [the dihedral angle = 87.73 (16°]. There is no intermolecular hydrogen bonding in the crystal structure.

  18. Easy transition path sampling methods: flexible-length aimless shooting and permutation shooting.

    Science.gov (United States)

    Mullen, Ryan Gotchy; Shea, Joan-Emma; Peters, Baron

    2015-06-09

    We present new algorithms for conducting transition path sampling (TPS). Permutation shooting rigorously preserves the total energy and momentum of the initial trajectory and is simple to implement even for rigid water molecules. Versions of aimless shooting and permutation shooting that use flexible-length trajectories have simple acceptance criteria and are more computationally efficient than fixed-length versions. Flexible-length permutation shooting and inertial likelihood maximization are used to identify the reaction coordinate for vacancy migration in a two-dimensional trigonal crystal of Lennard-Jones particles. The optimized reaction coordinate eliminates nearly all recrossing of the transition state dividing surface.

  19. Penyerbukan Pada Rambutan (Nepheuum Lappaceum L. Var. Lappaceum)

    OpenAIRE

    UJI, TAHAN

    1987-01-01

    TAHAN UJI.1987.Pollination in Nephelium lappaceum L. var.lappaceum. Suppl.Berita Biologi. 3 : 31 - 34.Inflorescence morphology,flowering biology and insect visitors of rambutan (Nephelium lappaceum L. var.lappaceum) were observed in Semboja, East Kalimantan.Rambutan is dioeceous plant and cross pollinated by insect.It was showed that in isolated inflorescence failed to produce fruits.Six species of bees i.e. Apisindica,Trigone itama,T. nitidiventris. T. canifronsT.irridipenis and T.atripes ar...

  20. Phenotypic plasticity of wall ultrastructure in the green alga Pediastrum s.l. (Chlorophyta, Sphaeropleales

    Directory of Open Access Journals (Sweden)

    Lenarczyk Joanna

    2016-07-01

    Full Text Available This study examined wall ultrastructure variability in the microscopic green alga Pediastrum s.l. Its value as a diagnostic character is discussed. Field and cultured material of 21 taxa were compared using light and scanning electron microscopy. Nine ultrastructural elements occurring on the surface of Pediastrum are documented with LM and SEM micrographs. The highest number of taxa showed reticulate ornamentation composed of a trigonal mesh and granules situated on its corners. The paper considers the use of wall ultrastructure to reconcile traditional and modern taxonomical systems with regard to Pediastrum varieties, and addresses the phylogenetic relationships between strains representing different varieties.