WorldWideScience

Sample records for ccaat-binding complex coordinates

  1. Sterol Biosynthesis and Azole Tolerance Is Governed by the Opposing Actions of SrbA and the CCAAT Binding Complex.

    Science.gov (United States)

    Gsaller, Fabio; Hortschansky, Peter; Furukawa, Takanori; Carr, Paul D; Rash, Bharat; Capilla, Javier; Müller, Christoph; Bracher, Franz; Bowyer, Paul; Haas, Hubertus; Brakhage, Axel A; Bromley, Michael J

    2016-07-01

    Azole drugs selectively target fungal sterol biosynthesis and are critical to our antifungal therapeutic arsenal. However, resistance to this class of drugs, particularly in the major human mould pathogen Aspergillus fumigatus, is emerging and reaching levels that have prompted some to suggest that there is a realistic probability that they will be lost for clinical use. The dominating class of pan-azole resistant isolates is characterized by the presence of a tandem repeat of at least 34 bases (TR34) within the promoter of cyp51A, the gene encoding the azole drug target sterol C14-demethylase. Here we demonstrate that the repeat sequence in TR34 is bound by both the sterol regulatory element binding protein (SREBP) SrbA, and the CCAAT binding complex (CBC). We show that the CBC acts complementary to SrbA as a negative regulator of ergosterol biosynthesis and show that lack of CBC activity results in increased sterol levels via transcriptional derepression of multiple ergosterol biosynthetic genes including those coding for HMG-CoA-synthase, HMG-CoA-reductase and sterol C14-demethylase. In agreement with these findings, inactivation of the CBC increased tolerance to different classes of drugs targeting ergosterol biosynthesis including the azoles, allylamines (terbinafine) and statins (simvastatin). We reveal that a clinically relevant mutation in HapE (P88L) significantly impairs the binding affinity of the CBC to its target site. We identify that the mechanism underpinning TR34 driven overexpression of cyp51A results from duplication of SrbA but not CBC binding sites and show that deletion of the 34 mer results in lack of cyp51A expression and increased azole susceptibility similar to a cyp51A null mutant. Finally we show that strains lacking a functional CBC are severely attenuated for pathogenicity in a pulmonary and systemic model of aspergillosis. PMID:27438727

  2. Coordination Control Of Complex Machines

    NARCIS (Netherlands)

    J.C.M. Baeten; B. van Beek; J. Markovski; L.J.A.M. Somers

    2015-01-01

    Control and coordination are important aspects of the development of complex machines due to an ever-increasing demand for better functionality, quality, and performance. In WP6 of the C4C project, we developed a synthesis-centric systems engineering framework suitable for supervisory coordination o

  3. Wave propagation in complex coordinates

    Science.gov (United States)

    Horsley, S. A. R.; King, C. G.; Philbin, T. G.

    2016-04-01

    We give an interpretation for the use of complex spatial coordinates in electromagnetism, in terms of a family of closely related inhomogeneous media. Using this understanding we find that the phenomenon of reflection can be related to branch cuts in the wave that originate from poles of ε (z) at complex positions. Demanding that these branch cuts disappear, we derive a new large family of inhomogeneous media that are reflectionless for a single angle of incidence. Extending this property to all angles of incidence leads us to a generalized form of the Pöschl Teller potentials that in general include regions of loss and gain. We conclude by analyzing our findings within the phase integral (WKB) method, and find another very large family of isotropic planar media that from one side have a transmission of unity and reflection of zero, for all angles of incidence.

  4. Aqueous coordination complexes of neptunium

    International Nuclear Information System (INIS)

    Thecomplex formation constants, obtained by different methods, for the complexing of neptunium, in different oxidation states, in aqueous solutions, with several organic and inorganic ligands, have been critically reviewed. The values for the thermodynamic parameters associated with the complex formation, wherever available, are also presented. (author)

  5. Coordination Approaches for Complex Software Systems

    NARCIS (Netherlands)

    Bosse, T.; Hoogendoorn, M.; Treur, J.

    2006-01-01

    This document presents the results of a collaboration between the Vrije Universiteit Amsterdam, Department of Artificial Intelligence and Force Vision to investigate coordination approaches for complex software systems. The project was funded by Force Vision.

  6. Wave propagation in complex coordinates

    CERN Document Server

    Horsley, S A R; Philbin, T G

    2015-01-01

    We investigate the analytic continuation of wave equations into the complex position plane. For the particular case of electromagnetic waves we provide a physical meaning for such an analytic continuation in terms of a family of closely related inhomogeneous media. For bounded permittivity profiles we find the phenomenon of reflection can be related to branch cuts in the wave that originate from poles of the permittivity at complex positions. Demanding that these branch cuts disappear, we derive a large family of inhomogeneous media that are reflectionless for a single angle of incidence. Extending this property to all angles of incidence leads us to a generalized form of the Poschl Teller potentials. We conclude by analyzing our findings within the phase integral (WKB) method.

  7. Deriving force field parameters for coordination complexes

    DEFF Research Database (Denmark)

    Norrby, Per-Ola; Brandt, Peter

    2001-01-01

    The process of deriving molecular mechanics force fields for coordination complexes is outlined. Force field basics are introduced with an emphasis on special requirements for metal complexes. The review is then focused on how to set up the initial model, define the target, refine the parameters...

  8. Novel Intramolecular Coordination Chemistry of Some New Metallocene Complexes

    Institute of Scientific and Technical Information of China (English)

    钱延龙; 黄吉玲

    2001-01-01

    This article summarizes the recent results of systematic study on the novel intramolecular cordination chemistry of some new substituted metallocene complexes made by our research group.It deals with the syntheses,reactions,structures of 65 new substituted metallocene complexes and some application of such coordination in homogeneous ctalysis,especially the structural chemistry of such novel intramolecular coordination complexes,and the mechanism of elimination and cyclization of such coordination compounds,as well as their control action in catalytic reactions.

  9. Iteration Complexity Analysis of Block Coordinate Descent Methods

    OpenAIRE

    Hong, Mingyi; Wang, Xiangfeng; Razaviyayn, Meisam; Luo, Zhi-Quan

    2013-01-01

    In this paper, we provide a unified iteration complexity analysis for a family of general block coordinate descent (BCD) methods, covering popular methods such as the block coordinate gradient descent (BCGD) and the block coordinate proximal gradient (BCPG), under various different coordinate update rules. We unify these algorithms under the so-called Block Successive Upper-bound Minimization (BSUM) framework, and show that for a broad class of multi-block nonsmooth convex problems, all algor...

  10. Extraordinary aluminum coordination in a novel homometallic double complex salt.

    Science.gov (United States)

    Mandai, Toshihiko; Masu, Hyuma; Johansson, Patrik

    2015-07-01

    We have characterized a novel aluminum-based homometallic double complex salt, incorporating discrete octa-coordinated cationic [Al(G3)2](3+) and hexa-coordinated anionic [Al(TfO)4(OH)2](3-) complexes (G3 = triglyme, TfO = trifluoromethanesulfonate). X-ray crystallography, Raman spectra, and DFT calculations demonstrate extraordinary weak Al(3+) coordination in [Al(G3)2](3+). PMID:26024493

  11. Phase diagram of coacervate complexes containing reversible coordination

    NARCIS (Netherlands)

    Wang, J.; Cohen Stuart, M.A.; Gucht, van der J.

    2012-01-01

    Phase separation of coacervate complexes from cationic PDMAEMA [poly(N,N-dimethylaminoethyl methacrylate)] and anionic reversible coordination polymers are studied in the present work. The coordination polymers are formed from zinc and a bis-ligand L2EO4 [1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9

  12. Coordination field analysis of rare earth complexes with triangular symmetry

    Institute of Scientific and Technical Information of China (English)

    范英芳; 潘大丰; 杨频

    1997-01-01

    The calculation of the complex matrixes in odd triangular symmetry was accomplished.The configurations of the coordination unit with various triangular symmetries and different ligand numbers were discussed.On the basis of the double-sphere coordination point-charge (DSCPCF) model,the detailed forms of the DSCPCF parameters Bmk and the expressions of the perturbation matrix elements in triangular field (D3,D3h,D3d) were derived.Thereby,the calculation scheme of coordination field perturbation energy of the rare earth complexes with triangular symmetry was constructed After the calculation scheme was programmed,the Stark energies of the crystalline TbAl3(BO3)4 were calculated The results were considerably close to the experimental values

  13. Microporous coordination complex and method of making the same

    Science.gov (United States)

    Matzger, Adam J.; Koh, Kyoungmoo

    2016-05-31

    Disclosed herein is a three-dimensional coordination complex that includes a plurality of inorganic centers; a plurality of a first bis(bidentate) linker; and a plurality of a second bis(bidentate) linker, where the first and the second bis(bidentate) linkers are have different lengths, and the bidentate binding sites on each linker face in opposite directions on an axis.

  14. Coordinating complex problem-solving among distributed intelligent agents

    Science.gov (United States)

    Adler, Richard M.

    1992-01-01

    A process-oriented control model is described for distributed problem solving. The model coordinates the transfer and manipulation of information across independent networked applications, both intelligent and conventional. The model was implemented using SOCIAL, a set of object-oriented tools for distributing computing. Complex sequences of distributed tasks are specified in terms of high level scripts. Scripts are executed by SOCIAL objects called Manager Agents, which realize an intelligent coordination model that routes individual tasks to suitable server applications across the network. These tools are illustrated in a prototype distributed system for decision support of ground operations for NASA's Space Shuttle fleet.

  15. Actinide coordination sphere in various U, Np and Pu nitrato coordination complexes

    International Nuclear Information System (INIS)

    Waste management of nuclear fuel represents one of the major environmental concerns of the decade. To recycle fissile valuable materials, intimate knowledge of complexation mechanisms involved in the solvent extraction processes is indispensable. Evolution of the actinide coordination sphere of AnO2(NO3)2TBP-type complexes (an = U, Np, Pu; TBP = tributylphosphate) with the actinide valence state have been probed by XAS at the metal LIII edge. Dramatic changes in the actinide coordination sphere appeared when the An(VI) metal is reduced to An(IV). However, no significant evolution in the actinide environment has been noticed across the series UO22+, NpO22+ and PuO22+. (au)

  16. Energetic lanthanide complexes: coordination chemistry and explosives applications

    International Nuclear Information System (INIS)

    Metals are generally added to organic molecular explosives in a heterogeneous composite to improve overall heat and energy release. In order to avoid creating a mixture that can vary in homogeneity, energetic organic molecules can be directly bonded to high molecular weight metals, forming a single metal complex with Angstrom-scale separation between the metal and the explosive. To probe the relationship between the structural properties of metal complexes and explosive performance, a new series of energetic lanthanide complexes has been prepared using energetic ligands such as NTO (5-nitro-2,4-dihydro-1,2,4-triazole-3-one). These are the first examples of lanthanide NTO complexes where no water is coordinated to the metal, demonstrating novel control of the coordination environment. The complexes have been characterized by X-ray crystallography, NMR and IR spectroscopies, photoluminescence, and sensitivity testing. The structural and energetic properties are discussed in the context of enhanced blast effects and detection. Cheetah calculations have been performed to fine-tune physical properties, creating a systematic method for producing explosives with 'tailor made' characteristics. These new complexes will be benchmarks for further study in the field of metalized high explosives.

  17. Coordinated aggregation in complex systems:. an interdisciplinary approach

    Science.gov (United States)

    Basios, V.; Nicolis, S. C.; Deneubourg, J. L.

    2016-09-01

    The study of the topic of guided aggregation in biology brings together decision making, collective motion and the dynamical interplay between individuals and groups. At the same time it meets statistical mechanics and the physics of complex systems in a new paradigmatic thinking. We propose a research platform for implementation and for undertaking systematic studies of coordinated aggregation, in a truly multi- and inter-disciplinary fashion.

  18. Design, synthesis and study of coordination complexes for quantum computing

    OpenAIRE

    Aguilà Avilés, David

    2013-01-01

    This thesis presents different strategies for the design of molecular complexes with the requirements to be used as two-qubit quantum gates. The approaches followed towards the preparation of potential qubit systems have been carried out focusing on the synthesis of ligands with β-diketone coordination units, which are very versatile for the design of metallocluster assemblies. One of the main advantages of using this kind of ligands is that they can be easily prepared through simple Claisen ...

  19. Complex Fenchel-Nielsen coordinates with small imaginary parts

    CERN Document Server

    Šarić, Dragomir

    2012-01-01

    Kahn and Markovic \\cite{KahnMark} proved that the fundamental group of each closed hyperbolic three manifold contains a closed surface subgroup. One of the main ingredients in their proof is a theorem which states that an assignment of nearly real, complex Fenchel-Nielsen coordinates to the cuffs of a pants decomposition of a closed surface $S$ induces a quasiFuchsian representation of the fundamental group of $S$. We give a new proof of this theorem with a slightly stronger conditions on the Fenchel-Nielsen coordinates and explain how to use the exponential mixing of the geodesic flow on a closed hyperbolic three manifold to prove that our theorem is sufficient for the applications in the work of Kahn and Markovic \\cite{KahnMark}.

  20. Isocyanide and Phosphine Oxide Coordination in Binuclear Chromium Pacman Complexes.

    Science.gov (United States)

    Stevens, Charlotte J; Nichol, Gary S; Arnold, Polly L; Love, Jason B

    2013-12-01

    The new binuclear chromium Pacman complex [Cr2(L)] of the Schiff base pyrrole macrocycle H4L has been synthesized and structurally characterized. Addition of isocyanide, C≡NR (R = xylyl, (t)Bu), or triphenylphosphine oxide donors to [Cr2(L)] gives contrasting chemistry with the formation of the new coordination compounds [Cr2(μ-CNR)(L)], in which the isocyanides bridge the two Cr(II) centers, and [Cr2(OPPh3)2(L)], a Cr(II) phosphine oxide adduct with the ligands exogenous to the cleft.

  1. Design of magnetic coordination complexes for quantum computing.

    Science.gov (United States)

    Aromí, Guillem; Aguilà, David; Gamez, Patrick; Luis, Fernando; Roubeau, Olivier

    2012-01-21

    A very exciting prospect in coordination chemistry is to manipulate spins within magnetic complexes for the realization of quantum logic operations. An introduction to the requirements for a paramagnetic molecule to act as a 2-qubit quantum gate is provided in this tutorial review. We propose synthetic methods aimed at accessing such type of functional molecules, based on ligand design and inorganic synthesis. Two strategies are presented: (i) the first consists in targeting molecules containing a pair of well-defined and weakly coupled paramagnetic metal aggregates, each acting as a carrier of one potential qubit, (ii) the second is the design of dinuclear complexes of anisotropic metal ions, exhibiting dissimilar environments and feeble magnetic coupling. The first systems obtained from this synthetic program are presented here and their properties are discussed.

  2. Ytterbium Coordination Polymer with Four Different Coordination Numbers: The First Structural Characterization of Lanthanide Phthalate Complex

    Institute of Scientific and Technical Information of China (English)

    WAN,Yong-Hong(万永红); JIN,Lin-Pei(金林培); WANG,Ke-Zhi(王科志)

    2002-01-01

    The novel ytterbium coordination polymer is a two-dimensional framework in which the central metal ions have four different coordination numhers and form four kinds of coordination polyhedra. The four kinds of coordination polyhedra connect into infinite chains by sharing oxygen atoms

  3. Similarities between GCS and human motor cortex: complex movement coordination

    Science.gov (United States)

    Rodríguez, Jose A.; Macias, Rosa; Molgo, Jordi; Guerra, Dailos

    2014-07-01

    The "Gran Telescopio de Canarias" (GTC1) is an optical-infrared 10-meter segmented mirror telescope at the ORM observatory in Canary Islands (Spain). The GTC control system (GCS), the brain of the telescope, is is a distributed object & component oriented system based on RT-CORBA and it is responsible for the management and operation of the telescope, including its instrumentation. On the other hand, the Human motor cortex (HMC) is a region of the cerebrum responsible for the coordination of planning, control, and executing voluntary movements. If we analyze both systems, as far as the movement control of their mechanisms and body parts is concerned, we can find extraordinary similarities in their architectures. Both are structured in layers, and their functionalities are comparable from the movement conception until the movement action itself: In the GCS we can enumerate the Sequencer high level components, the Coordination libraries, the Control Kit library and the Device Driver library as the subsystems involved in the telescope movement control. If we look at the motor cortex, we can also enumerate the primary motor cortex, the secondary motor cortices, which include the posterior parietal cortex, the premotor cortex, and the supplementary motor area (SMA), the motor units, the sensory organs and the basal ganglia. From all these components/areas we will analyze in depth the several subcortical regions, of the the motor cortex, that are involved in organizing motor programs for complex movements and the GCS coordination framework, which is composed by a set of classes that allow to the high level components to transparently control a group of mechanisms simultaneously.

  4. Coordination Chemistry of Homoleptic Actinide(IV)-Thiocyanate Complexes.

    Science.gov (United States)

    Carter, Tyler J; Wilson, Richard E

    2015-10-26

    The synthesis, X-ray crystal structure, vibrational and optical spectroscopy for the eight-coordinate thiocyanate compounds, [Et4 N]4 [Pu(IV) (NCS)8 ], [Et4 N]4 [Th(IV) (NCS)8 ], and [Et4 N]4 [Ce(III) (NCS)7 (H2 O)] are reported. Thiocyanate was found to rapidly reduce plutonium to Pu(III) in acidic solutions (pHthiocyanate complex [Et4 N]4 [Pu(IV) (NCS)8 ] was crystallized when a large excess of [Et4 N][NCS] was present. This compound, along with its U(IV) analogue, maintains inner-sphere thiocyanate coordination in acetonitrile based on the observation of intense ligand-to-metal charge-transfer bands. Spectroscopic and crystallographic data do not support the interaction of the metal orbitals with the ligand π system, but support an enhanced An(IV) -NCS interaction, as the Lewis acidity of the metal ion increases from Th to Pu. PMID:26493880

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

    Science.gov (United States)

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

    2008-09-01

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

  6. Complex coacervate core micelles from iron-based coordination polymers.

    Science.gov (United States)

    Wang, Junyou; de Keizer, Arie; Fokkink, Remco; Yan, Yun; Cohen Stuart, Martien A; van der Gucht, Jasper

    2010-07-01

    Complex coacervate core micelles (C3Ms) from cationic poly(N-methyl-2-vinyl-pyridinium iodide)-b-poly(ethylene oxide) (P2MVP(41)-b-PEO(205)) and anionic iron coordination polymers are investigated in the present work. Micelle formation is studied by light scattering for both Fe(II)- and Fe(III)-containing C3Ms. At the stoichiometric charge ratio, both Fe(II)-C3Ms and Fe(III)-C3Ms are stable for at least 1 week at room temperature. Excess of iron coordination polymers has almost no effect on the formed Fe(II)-C3Ms and Fe(III)-C3Ms, whereas excess of P2MVP(41)-b-PEO(205) copolymers in the solution can dissociate the formed micelles. Upon increasing salt concentration, the scattering intensity decreases. This decrease is due to both a decrease in the number of micelles (or an increase in CMC) and a decrease in aggregation number. The salt dependence of the CMC and the aggregation number is explained using a scaling argument for C3M formation. Compared with Fe(II)-C3Ms, Fe(III)-C3Ms have a lower CMC and a higher stability against dissociation by added salt.

  7. Six-coordinate uranium complexes featuring a bidentate anilide ligand

    Energy Technology Data Exchange (ETDEWEB)

    Fox, A.R.; Silvia, J.S.; Townsend, E.M.; Cummins, Ch.C. [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA (United States)

    2010-06-15

    The synthesis of a new bidentate anilide ligand and four uranium amide complexes utilizing the ligand are reported. The secondary aniline HN[R]Ar{sub Met} (R = C(CD{sub 3}){sub 2}CH{sub 3}, Ar{sub Met} = 2-NMe{sub 2}-5-MeC{sub 6}H{sub 3}) is prepared by condensation of H{sub 2}NAr{sub Met} and acetone-d6 followed by alkylation of the resulting imine with MeLi. The ligand precursors (Et{sub 2}O)Li(N[R]Ar{sub Met}) and K(N[R]Ar{sub Met}) are prepared through deprotonation of HN[R]Ar{sub Met} with n-BuLi and KH, respectively. Treatment of UI{sub 3}(THF){sub 4} with (Et{sub 2}O)Li(N[R]Ar{sub Met}) (2 equiv) provides the uranium(III) -ate complex Li[I{sub 2}U(N[R]Ar{sub Met}){sub 2}] (Li[1]), while treatment of UI{sub 3} with three equiv. of K(N[R]Ar{sub Met}) provides the neutral uranium(III) complex U(N[R]Ar{sub Met}){sub 3} (2). Both uranium(III) complexes are susceptible to 1e oxidation, as is demonstrated by the syntheses of the uranium(IV) derivatives I{sub 2}U(N[R]Ar{sub Met}){sub 2} (1) and [U(N[R]Ar{sub Met}){sub 3}][OTf] ([2][OTf]; OTf=CF{sub 3}SO{sub 3}). The spectroscopic and X-ray structural characterization of all four uranium complexes is described. The structures of 2 and [2][OTf] exhibit a large degree of steric pressure about the uranium center, effectively preventing the [2]{sup +} ion from achieving a seven-coordinate structure. (authors)

  8. Programmer Cognition in Explicit Coordination Modeling: Understanding the Design of Complex Human Interaction and Coordination

    OpenAIRE

    Lin, Sirong

    2011-01-01

    Parallel thinking is a mindset that enables computer scientists to think about and implement systems that allow activities to happen concurrently. This mindset is needed in designing and implementing a wide range of computer systems involving coordinated components (e.g., parallel, distributed, and multi-user systems). No matter what the coordinated component is, whether human or computer, the underlying issue is to imagine coordination between these components and manage the distribution a...

  9. Attributes of advanced practice registered nurse care coordination for children with medical complexity.

    Science.gov (United States)

    Cady, Rhonda G; Kelly, Anne M; Finkelstein, Stanley M; Looman, Wendy S; Garwick, Ann W

    2014-01-01

    Care coordination is an essential component of the pediatric health care home. This study investigated the attributes of relationship-based advanced practice registered nurse care coordination for children with medical complexity enrolled in a tertiary hospital-based health care home. Retrospective review of 2,628 care coordination episodes conducted by telehealth over a consecutive 3-year time period for 27 children indicated that parents initiated the majority of episodes and the most frequent reason was acute and chronic condition management. During this period, care coordination episodes tripled, with a significant increase (p care coordination model has potential for changing the health management processes for children with medical complexity.

  10. Two new coordination polymers, a trinuclear metal complex and their interconversion depending on the solvent.

    Science.gov (United States)

    Koike, Shiori; Hirakawa, Takeshi; Yamanishi, Katsunori; Kondo, Mitsuru

    2014-09-14

    Two new 1-D coordination polymers and a discrete trinuclear complex with a double-ring framework were synthesized and structurally characterized. The unique irreversible conversion from one of the 1-D coordination polymers to the trinuclear complex by contact with MeCN is described.

  11. Recent advances in nanoparticle carriers for coordination complexes.

    Science.gov (United States)

    Sato, Mariana Rillo; da Silva, Patricia Bento; de Souza, Rodrigo Alves; dos Santos, Karen Cristina; Chorilli, Marlus

    2015-01-01

    Coordination compounds are substances in which a central metal atom is bonded to nonmetal atoms, or groups of atoms, called ligands. Examples include vitamin B12, hemoglobin, chlorophyll, dyes and pigments, as well as catalysts used in organic synthesis. Coordination compounds have received much attention in recent years. This interest was prompted by the discovery that several coordination compounds exhibit activity against bacteria, fungi and cancer. Some coordination compounds are not in clinical use, because of poor water solubility. Because they are unable to cross the lipid membranes of cells, bioavailability and efficacy are low. Some researchers have applied nanotechnology to coordination compounds, hoping to reduce the number of doses required and the severity of side effects, and also to improve biological activity. Nanotechnology can deliver active components in sufficient concentrations throughout treatment, guiding it to the desired location of action; conventional treatments do not meet these requirements. In this study we review some drug delivery systems based on nanotechnology, such as microemulsions (MEs), cyclodextrin (CD), polymeric nanoparticles (PN), solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), magnetic and gold nanoparticles (MNPs / AuNPs) and liquid crystalline systems (LC), and coordination compounds. PMID:25579344

  12. [Complex chronic care situations and socio-health coordination].

    Science.gov (United States)

    Morilla Herrera, Juan Carlos; Morales Asencio, José Miguel; Kaknani, Shakira; García Mayor, Silvia

    2016-01-01

    Patient-centered healthcare is currently one of the most pursued goals in health services. It is necessary to ensure a sufficient level of cooperative and coordinated work between different providers and settings, including family and social and community resources. Clinical integration occurs when the care provided by health professionals and providers is integrated into a single coherent process through different professions using shared guidelines and protocols. Such coordination can be developed at three levels: macro, which involves the integration of one or more of the three basic elements that support health care (the health plan, primary care and specialty care), with the aim of reducing fragmentation of care; meso, where health and social services are coordinated to provide comprehensive care to elderly and chronic patients; and micro, aimed to improve coordination in individual patients and caregivers. The implementation of new roles, such as Advanced Practice Nursing, along with improvements in family physicians' problem-solving capacity in certain processes, or modifying the place of provision of certain services are key to ensure services adapted to the requirements of chronic patients.

  13. Coordination Chemistry of Disilylated Stannylenes with Group 10 d10 Transition Metals: Silastannene vs Stannylene Complexation

    OpenAIRE

    Arp, Henning; Marschner, Christoph; Baumgartner, Judith; Zark, Patrick; Müller, Thomas

    2013-01-01

    The coordination behavior of disilylated stannylenes toward zerovalent group 10 transition metal complexes was studied. This was accomplished by reactions of PEt3 adducts of disilylated stannylenes with zerovalent group 10 transition metal complexes. The thus obtained products differed between the first row example nickel and its heavier congeners. While with nickel stannylene complex formation was observed, coordination of the stannylenes to palladium and platinum compounds led to unusual si...

  14. Identification of different coordination geometries by XAFS in copper(II) complexes with trimesic acid

    Science.gov (United States)

    Gaur, A.; Klysubun, W.; Soni, Balram; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

    2016-10-01

    X-ray absorption spectroscopy (XAS) is very useful in revealing the information about geometric and electronic structure of a transition-metal absorber and thus commonly used for determination of metal-ligand coordination. But XAFS analysis becomes difficult if differently coordinated metal centers are present in a system. In the present investigation, existence of distinct coordination geometries around metal centres have been studied by XAFS in a series of trimesic acid Cu(II) complexes. The complexes studied are: Cu3(tma)2(im)6 8H2O (1), Cu3(tma)2(mim)6 17H2O (2), Cu3(tma)2(tmen)3 8.5H2O (3), Cu3(tma) (pmd)3 6H2O (ClO4)3 (4) and Cu3(tma)2 3H2O (5). These complexes have not only Cu metal centres with different coordination but in complexes 1-3, there are multiple coordination geometries present around Cu centres. Using XANES spectra, different coordination geometries present in these complexes have been identified. The variation observed in the pre-edge features and edge features have been correlated with the distortion of the specific coordination environment around Cu centres in the complexes. XANES spectra have been calculated for the distinct metal centres present in the complexes by employing ab-initio calculations. These individual spectra have been used to resolve the spectral contribution of the Cu centres to the particular XANES features exhibited by the experimental spectra of the multinuclear complexes. Also, the variation in the 4p density of states have been calculated for the different Cu centres and then correlated with the features originated from corresponding coordination of Cu. Thus, these spectral features have been successfully utilized to detect the presence of the discrete metal centres in a system. The inferences about the coordination geometry have been supported by EXAFS analysis which has been used to determine the structural parameters for these complexes.

  15. Distributed detection of communities in complex networks using synthetic coordinates

    International Nuclear Information System (INIS)

    Various applications like finding Web communities, detecting the structure of social networks, and even analyzing a graph’s structure to uncover Internet attacks are just some of the applications for which community detection is important. In this paper, we propose an algorithm that finds the entire community structure of a network, on the basis of local interactions between neighboring nodes and an unsupervised distributed hierarchical clustering algorithm. The novelty of the proposed approach, named SCCD (standing for synthetic coordinate community detection), lies in the fact that the algorithm is based on the use of Vivaldi synthetic network coordinates computed by a distributed algorithm. The current paper not only presents an efficient distributed community finding algorithm, but also demonstrates that synthetic network coordinates could be used to derive efficient solutions to a variety of problems. Experimental results and comparisons with other methods from the literature are presented for a variety of benchmark graphs with known community structure, derived from varying a number of graph parameters and real data set graphs. The experimental results and comparisons to existing methods with similar computation cost on real and synthetic data sets demonstrate the high performance and robustness of the proposed scheme. (paper)

  16. Coordinating complex decision support activities across distributed applications

    Science.gov (United States)

    Adler, Richard M.

    1994-01-01

    Knowledge-based technologies have been applied successfully to automate planning and scheduling in many problem domains. Automation of decision support can be increased further by integrating task-specific applications with supporting database systems, and by coordinating interactions between such tools to facilitate collaborative activities. Unfortunately, the technical obstacles that must be overcome to achieve this vision of transparent, cooperative problem-solving are daunting. Intelligent decision support tools are typically developed for standalone use, rely on incompatible, task-specific representational models and application programming interfaces (API's), and run on heterogeneous computing platforms. Getting such applications to interact freely calls for platform independent capabilities for distributed communication, as well as tools for mapping information across disparate representations. Symbiotics is developing a layered set of software tools (called NetWorks! for integrating and coordinating heterogeneous distributed applications. he top layer of tools consists of an extensible set of generic, programmable coordination services. Developers access these services via high-level API's to implement the desired interactions between distributed applications.

  17. Low-Complexity MMSE Precoding for Coordinated Multipoint with Per-Antenna Power Constraint

    DEFF Research Database (Denmark)

    Kim, Tae Min; Sun, Fan; Paulraj, Arogyaswami

    2013-01-01

    We propose a low-complexity minimum mean square error (MMSE) transmit filter design for the coordinated beamforming (CB) in the coordinated multipoint (CoMP) under the practical per-antenna power constraint (PAPC). The proposed design is based on the non-linear Gauss-Seidel type algorithm in which...

  18. A formula on linear complexity of highest coordinate sequences from maximal periodic sequences over Galois rings

    Institute of Scientific and Technical Information of China (English)

    HU Lei; SUN Nigang

    2006-01-01

    Using a polynomial expression of the highest coordinate map, we deduce an exact formula on the linear complexity of the highest coordinate sequence derived from a maximal periodic sequence over an arbitrary Galois ring of characteristic p2 , where p is a prime. This generalizes the known result of Udaya and Siddiqi for the case that the Galois ring is Z4.

  19. Equilibrium between Different Coordination Geometries in Oxidovanadium(IV) Complexes

    Science.gov (United States)

    Ugone, Valeria; Garribba, Eugenio; Micera, Giovanni; Sanna, Daniele

    2015-01-01

    In this laboratory activity, the equilibrium between square pyramidal and octahedral V(IV)O[superscript 2+] complexes is described. We propose a set of experiments to synthesize and characterize two types of V(IV)O[superscript 2+] complexes. The experiment allows great flexibility and may be effectively used at a variety of levels and the activity…

  20. Anticancer Activities of Mononuclear Ruthenium(II) Coordination Complexes

    OpenAIRE

    Motswainyana, William M.; Ajibade, Peter A.

    2015-01-01

    Ruthenium compounds are highly regarded as potential drug candidates. The compounds offer the potential of reduced toxicity and can be tolerated in vivo. The various oxidation states, different mechanism of action, and the ligand substitution kinetics of ruthenium compounds give them advantages over platinum-based complexes, thereby making them suitable for use in biological applications. Several studies have focused attention on the interaction between active ruthenium complexes and their po...

  1. Facile Synthesis of Functionalized Carbene Metal Complexes from Coordinated Isonitriles.

    Science.gov (United States)

    Lothschütz, Christian; Wurm, Thomas; Zeiler, Anna; Freiherr V Falkenhausen, Alexander; Rudolph, Matthias; Rominger, Frank; Hashmi, A Stephen K

    2016-02-01

    The scope and limitations of the isonitrile-based NHC template synthesis were investigated with a series of precursors containing a nucleophilic amine in combination with tethered electrophiles. In the case of alkynes and phosphonic esters as electrophiles no ring closure was observed and new functionalized NAC gold complexes were obtained. By the use of unsaturated esters and phosphonic esters as Michael acceptors in the amine precursors, ester-modified gold and palladium NHC complexes were accessible in high efficiency. PMID:26033484

  2. Macrocyclic pacman complexes for secondary coordination sphere control

    OpenAIRE

    Leeland, James William

    2011-01-01

    The work presented in this Thesis describes the design, synthesis and reactivity of a symmetric and various asymmetric Schiff-base macrocycles that are capable of forming a wedge-shaped “Pacman” conformation upon metal binding. Chapter One introduces catalysts for small molecule transformation as well as transition metal complexes of pyrrole-containing macrocycles. Further to this, Pacman systems, including previous work from Love and co-workers, and complexes capable of secondary coordinatio...

  3. Proton exchange in acid–base complexes induced by reaction coordinates with heavy atom motions

    International Nuclear Information System (INIS)

    Highlights: ► Proton exchange in acid–base complexes is studied. ► The structures, binding energies, and normal mode vibrations are calculated. ► Transition state structures of proton exchange mechanism are determined. ► In the complexes studied, the reaction coordinate involves heavy atom rocking. ► The reaction coordinate is not simply localized in the proton movements. - Abstract: We extend previous work on nitric acid–ammonia and nitric acid–alkylamine complexes to illustrate that proton exchange reaction coordinates involve the rocking motion of the base moiety in many double hydrogen-bonded gas phase strong acid–strong base complexes. The complexes studied involve the biologically and atmospherically relevant glycine, formic, acetic, propionic, and sulfuric acids with ammonia/alkylamine bases. In these complexes, the magnitude of the imaginary frequencies associated with the proton exchange transition states are −1. This contrasts with widely studied proton exchange reactions between symmetric carboxylic acid dimers or asymmetric DNA base pair and their analogs where the reaction coordinate is localized in proton motions and the magnitude of the imaginary frequencies for the transition states are >1100 cm−1. Calculations on complexes of these acids with water are performed for comparison. Variations of normal vibration modes along the reaction coordinate in the complexes are described.

  4. Coordination Chemistry of Homoleptic Actinide(IV)-Thiocyanate Complexes.

    Science.gov (United States)

    Carter, Tyler J; Wilson, Richard E

    2015-10-26

    The synthesis, X-ray crystal structure, vibrational and optical spectroscopy for the eight-coordinate thiocyanate compounds, [Et4 N]4 [Pu(IV) (NCS)8 ], [Et4 N]4 [Th(IV) (NCS)8 ], and [Et4 N]4 [Ce(III) (NCS)7 (H2 O)] are reported. Thiocyanate was found to rapidly reduce plutonium to Pu(III) in acidic solutions (pHcoordination in acetonitrile based on the observation of intense ligand-to-metal charge-transfer bands. Spectroscopic and crystallographic data do not support the interaction of the metal orbitals with the ligand π system, but support an enhanced An(IV) -NCS interaction, as the Lewis acidity of the metal ion increases from Th to Pu.

  5. Coordination Complexes as Inorganic Explosives for Initiation Systems

    Institute of Scientific and Technical Information of China (English)

    依留申 M A; 泽林斯基 I V

    2004-01-01

    The study of the synthesis of coordination compounds in the series of perchlorates of d-metals containing polynitrogen heterocyclic ligands is presented in the following report. The major part of the report is also devoted to the investigations of properties of the compounds obtained and their applications in safe electric and laser detonators.%介绍了含多氮杂环配位体的过氯酸盐系列络合物的合成研究.主要对新合成的化合物进行了性能研究及在安全电雷管和激光雷管的应用研究.

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

    Science.gov (United States)

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

    2014-10-01

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

  7. Biphenolate Iron (II) Complexes with Intramolecularly Coordinating Nitrogen Lewis Bases

    NARCIS (Netherlands)

    Koten, G. van; Brandts, J.A.M.; Janssen, M.D.; Hogerheide, M.P.; Boersma, J.; Spek, A.L.

    1999-01-01

    The synthesis and characterisation of a novel Fe(II) bisphenolate complex [Fe(OC{6}H{4}CH{2}NMe{2}-2){2}]{2} (1) from [Na(OC{6}H{4}CH{2}NMe{2}-2)] and anhydrous FeCl{2} is reported. The solid state structure has been elucidated by single crystal X-ray analysis and shows a dimeric structure with two

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

    Science.gov (United States)

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

    2014-04-29

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

  9. Plutonium(IV) complexation by diglycolamide ligands - coordination chemistry insight into TODGA-based actinide separations

    NARCIS (Netherlands)

    Reilly, S.D.; Gaunt, A.J.; Scott, B.L.; Modolo, G.; Iqbal, M.; Verboom, W.; Sarsfield, M.J.

    2012-01-01

    Complexation of Pu(IV) with TMDGA, TEDGA, and TODGA diglycolamide ligands was followed by vis-NIR spectroscopy. A crystal structure determination reveals that TMDGA forms a 1:3 homoleptic Pu(IV) complex with the nitrate anions forced into the outer coordination sphere

  10. Unusual κ1 coordination of a β-diketiminate ligand in niobium complexes.

    Science.gov (United States)

    Ziegler, Jessica A; Bergman, Robert G; Arnold, John

    2016-08-01

    Reaction of (BDI)Nb(N(t)Bu)Cl2py with NaCp results in the κ(1)-coordination of the BDI ligand in the complex (κ(1)-N,BDI)CpNb(N(t)Bu)Cl (2). Via chloride abstraction from 2, we develop synthetic routes to structurally analogous cationic and Nb(IV) pseudo-four coordinate complexes where the BDI ligand returns to the κ(2)-coordination mode. We compare these to our previously reported tetrahedral niobium bis(imido) complexes to investigate the effects of the Cp ligand on the properties of Nb-BDI-imido systems. Substitution of the chloride in 2 with a hydride also causes return to bidentate binding of the BDI ligand. The X-ray crystal structures of these complexes have been determined, and the structural parameters reflecting the consequences of the electronic differences are discussed. PMID:27461382

  11. Coordinatively unsaturated ruthenium complexes as efficient alkyneazide cycloaddition catalysts

    KAUST Repository

    Lamberti, Marina

    2012-01-23

    The performance of 16-electron ruthenium complexes with the general formula Cp*Ru(L)X (in which L = phosphine or N-heterocyclic carbene ligand; X = Cl or OCH2CF3) was explored in azidealkyne cycloaddition reactions that afford the 1,2,3- triazole products. The scope of the Cp*Ru(PiPr 3)Cl precatalyst was investigated for terminal alkynes leading to new 1,5-disubstituted 1,2,3-triazoles in high yields. Mechanistic studies were conducted and revealed a number of proposed intermediates. Cp*Ru- (PiPr3)(2-HCCPh)Cl was observed and characterized by 1H, 13C, and 31P NMR at temperatures between 273 and 213 K. A rare example of N,N-κ2-phosphazide complex, Cp*Ru(κ2- iPr3PN3Bn)Cl, was fully characterized, and a single-crystal X-ray diffraction structure was obtained. DFT calculations describe a complete map of the catalytic reactivity with phenylacetylene and/or benzylazide. © 2012 American Chemical Society.

  12. Modeling and Simulation of Complex Network Attributes on Coordinating Large Multiagent System

    Directory of Open Access Journals (Sweden)

    Yang Xu

    2014-01-01

    Full Text Available With the expansion of distributed multiagent systems, traditional coordination strategy becomes a severe bottleneck when the system scales up to hundreds of agents. The key challenge is that in typical large multiagent systems, sparsely distributed agents can only communicate directly with very few others and the network is typically modeled as an adaptive complex network. In this paper, we present simulation testbed CoordSim built to model the coordination of network centric multiagent systems. Based on the token-based strategy, the coordination can be built as a communication decision problem that agents make decisions to target communications and pass them over to the capable agents who will potentially benefit the team most. We have theoretically analyzed that the characters of complex network make a significant difference with both random and intelligent coordination strategies, which may contribute to future multiagent algorithm design.

  13. Role of the coordination center in photocurrent behavior of a tetrathiafulvalene and metal complex dyad.

    Science.gov (United States)

    Sun, Yong-Gang; Ji, Shu-Fang; Huo, Peng; Yin, Jing-Xue; Huang, Yu-De; Zhu, Qin-Yu; Dai, Jie

    2014-03-17

    Small organic molecule-based compounds are considered to be promising materials in photoelectronics and high-performance optoelectronic devices. However, photoelectron conversion research based on functional organic molecule and metal complex dyads is very scarce. We design and prepare a series of compounds containing a tetrathiafulvalene (TTF) moiety substituted with pyridylmethylamide groups of formulas [Ni(acac)2L]·2CH3OH (1), [Cu2I2L2]·THF·2CH3CN (2), and [MnCl2L2]n·2nCH3CH2OH (3) (L = 4,5-bis(3-pyridylmethylamide)-4',5'-bimethylthio-tetrathiafulvalene, acac = acetylacetone) to study the role of the coordination center in photocurrent behavior. Complex 1 is a mononuclear species, and complex 2 is a dimeric species. Complex 3 is a two-dimensional (2-D) coordination polymer. Spectroscopic and electrochemical properties of these complexes indicate that they are electrochemically active materials. The tetrathiafulvalene ligand L is a photoelectron donor in the presence of electron acceptor methylviologen. The effect of metal coordination centers on photocurrent response behavior is examined. The redox-active metal coordination centers should play an important role in improvement of the photocurrent response property. The different morphologies of the electrode films reflect the dimensions in molecular structures of the coordination compounds.

  14. Surprising Coordination Geometry Differences in Ce(IV)- and Pu(IV)-Maltol Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence Berkeley National Laboratory; Raymond, Kenneth; Szigethy, Geza; Xu, Jide; Gorden, Anne E.V.; Teat, Simon J.; Shuh, David K.; Raymond, Kenneth N.

    2008-02-12

    As part of a study to characterize the detailed coordination behavior of Pu(IV), single crystal X-ray diffraction structures have been determined for Pu(IV) and Ce(IV) complexes with the naturally-occurring ligand maltol (3-hydroxy-2-methyl-pyran-4-one) and its derivative bromomaltol (5-bromo-3-hydroxy-2-methyl-pyran-4-one). Although Ce(IV) is generally accepted as a structural analog for Pu(IV), and the maltol complexes of these two metals are isostructural, the corresponding bromomaltol complexes are strikingly different with respect to ligand orientation about the metal ion: All complexes exhibit trigonal dodecahedral coordination geometry but the Ce(IV)-bromomaltol complex displays an uncommon ligand arrangement not mirrored in the Pu(IV) complex, although the two metal species are generally accepted to be structural analogs.

  15. Scribble1/AP2 Complex Coordinates NMDA Receptor Endocytic Recycling

    Directory of Open Access Journals (Sweden)

    Nicolas H. Piguel

    2014-10-01

    Full Text Available The appropriate trafficking of glutamate receptors to synapses is crucial for basic synaptic function and synaptic plasticity. It is now accepted that NMDA receptors (NMDARs internalize and are recycled at the plasma membrane but also exchange between synaptic and extrasynaptic pools; these NMDAR properties are also key to governing synaptic plasticity. Scribble1 is a large PDZ protein required for synaptogenesis and synaptic plasticity. Herein, we show that the level of Scribble1 is regulated in an activity-dependent manner and that Scribble1 controls the number of NMDARs at the plasma membrane. Notably, Scribble1 prevents GluN2A subunits from undergoing lysosomal trafficking and degradation by increasing their recycling to the plasma membrane following NMDAR activation. Finally, we show that a specific YxxR motif on Scribble1 controls these mechanisms through a direct interaction with AP2. Altogether, our findings define a molecular mechanism to control the levels of synaptic NMDARs via Scribble1 complex signaling.

  16. Ion-polyether coordination complexes: crystalline ionic conductors for clean energy storage.

    Science.gov (United States)

    Bruce, Peter G

    2006-03-21

    Ion-polyether complexes are the solid state analogues of crown ether and cryptand complexes. They represent a fascinating class of coordination compounds in their own right, with the ability to support ionic conductivity and the potential to be used as electrolytes in all-solid-state rechargeable lithium batteries. Here the recent discovery of ionic conductivity in crystalline ion-polyether complexes, when for 30 years such materials were considered to be insulators, is described, along with their closely related structural chemistry.

  17. Overcoming Statistical Complexity: Selective Coordination of Three Different Metal Ions to a Ligand with Three Different Coordination Sites.

    Science.gov (United States)

    Akine, Shigehisa; Matsumoto, Takashi; Nabeshima, Tatsuya

    2016-01-18

    In general, it is difficult to selectively introduce different metal ions at specific positions of a cluster-like structure. This is mainly due to statistical problems as well as the reversibility of the formation of coordination bonds. To overcome this statistical problem, we used a carefully designed ligand, H6 L, which can accommodate three different kinds of metal ions in three types of coordination sites. The complex [LNiZn2La](3+), which contains three different metals, was quantitatively obtained by a stepwise procedure, but different products were obtained when the metal ions were added in a different order. However, equilibration studies indicated that this complex was almost solely formed among 54 (=3×3×3H2) possible products upon heating; the formation efficiency (ca. 100%) was significantly higher than the statistical probability (2.47%). Such carefully designed ligands should be useful for the synthesis multimetallic systems, which are of interest because of the interplay between the different metals.

  18. Slow magnetic relaxation in mononuclear seven-coordinate cobalt(II) complexes with easy plane anisotropy.

    Science.gov (United States)

    Chen, Lei; Chen, Shu-Yang; Sun, Yi-Chen; Guo, Yu-Mei; Yu, Lu; Chen, Xue-Tai; Wang, Zhenxing; Ouyang, Z W; Song, You; Xue, Zi-Ling

    2015-07-01

    Two mononuclear seven-coordinate cobalt(II) complexes [Co(L)3(NO3)2] (L = 4-tert-butylpyridine, 1; L = isoquinoline, 2) were prepared and structurally analyzed by single-crystal X-ray crystallography. The coordination spheres of 1 and 2 exhibit distorted pentagonal bipyramid geometry. Analysis of their direct-current magnetic data reveals the existence of easy plane anisotropy (D > 0) with a small transverse anisotropy (E), which was further confirmed by high-field electron paramagnetic resonance (HFEPR) spectroscopy. Field-induced slow magnetic relaxations were observed under the applied dc field in complexes 1 and 2 by alternating-current magnetic susceptibility measurements. Importantly, these complexes are new instances of mononuclear high-coordinate cobalt(II)-based single-molecule magnets. PMID:26027953

  19. Stereochemistry and solid-state circular dichroism spectroscopy of eight-coordinate chiral lanthanide complexes

    Institute of Scientific and Technical Information of China (English)

    ZHOU Nan; WAN ShiGang; ZHAO Jian; LIN YiJi; XUAN WeiMin; FANG XueMing; ZHANG Hui

    2009-01-01

    Eight-coordinate chiral lanthanide complexes[Eu(dbm)_3L~(RR)](1),[Eu(dbm)_3L~(SS)](2) and[Tb(dbm)_3L~(RR)](3)(L~(RR)/L~(SS)=(-)-1(+)-4,5-pineno-2,2'-bipyridine,Hdbm=dibenzoylmethane) were synthesized stereoselectively,which were characterized by UV-vis,CD spectra and X-ray single-crystal diffraction.The mirrorimage structure features of complexes 1 and 2 were obtained by combination of the solid-state CD spectra and the crystal structure analysis.After further comparison with the solid-state CD spectra of six-coordinate and seven-coordinate metal complexes containing β-diketone ligands,the CD spectraabsolute configuration correlation rule for the eight-coordinate β-diketonate lanthanide complexes was proposed through the exciton chirality method for the first time.The △ or Λ absolute configurations of complexes 1-3 with the distorted square antiprism geometry were confirmed by the X-ray single-crystal analysis.

  20. Stereochemistry and solid-state circular dichroism spectroscopy of eight-coordinate chiral lanthanide complexes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Eight-coordinate chiral lanthanide complexes [Eu(dbm)3LRR](1),[Eu(dbm)3LSS](2) and [Tb(dbm)3LRR](3)(LRR/LSS =(-)-/(+)-4,5-pineno-2,2’-bipyridine,Hdbm = dibenzoylmethane) were synthesized stereoselectively,which were characterized by UV-vis,CD spectra and X-ray single-crystal diffraction.The mirrorimage structure features of complexes 1 and 2 were obtained by combination of the solid-state CD spectra and the crystal structure analysis.After further comparison with the solid-state CD spectra of six-coordinate and seven-coordinate metal complexes containing β-diketone ligands,the CD spectraabsolute configuration correlation rule for the eight-coordinate β-diketonate lanthanide complexes was proposed through the exciton chirality method for the first time.The △ or Λ absolute configurations of complexes 1―3 with the distorted square antiprism geometry were confirmed by the X-ray single-crystal analysis.

  1. Multifunctionality of organometallic quinonoid metal complexes: surface chemistry, coordination polymers, and catalysts.

    Science.gov (United States)

    Kim, Sang Bok; Pike, Robert D; Sweigart, Dwight A

    2013-11-19

    Quinonoid metal complexes have potential applications in surface chemistry, coordination polymers, and catalysts. Although quinonoid manganese tricarbonyl complexes have been used as secondary building units (SBUs) in the formation of novel metal-organometallic coordination networks and polymers, the potentially wider applications of these versatile linkers have not yet been recognized. In this Account, we focus on these diverse new applications of quinonoid metal complexes, and report on the variety of quinonoid metal complexes that we have synthesized. Through the use of [(η(6)-hydroquinone)Mn(CO)3](+), we are able to modify the surface of Fe3O4 and FePt nanoparticles (NPs). This process occurs either by the replacement of oleylamine with neutral [(η(5)-semiquinone)Mn(CO)3] at the NP surface, or by the binding of anionic [(η(4)-quinone)Mn(CO)3](-) upon further deprotonation of [(η(5)-semiquinone)Mn(CO)3] at the NP surface. We have demonstrated chemistry at the intersection of surface-modified NPs and coordination polymers through the growth of organometallic coordination polymers onto the surface modified Fe3O4 NPs. The resulting magnetic NP/organometallic coordination polymer hybrid material exhibited both the unique superparamagnetic behavior associated with Fe3O4 NPs and the paramagnetism attributable to the metal nodes, depending upon the magnetic range examined. By the use of functionalized [(η(5)-semiquinone)Mn(CO)3] complexes, we attained the formation of an organometallic monolayer on the surface of highly ordered pyrolitic graphite (HOPG). The resulting organometallic monolayer was not simply a random array of manganese atoms on the surface, but rather consisted of an alternating "up and down" spatial arrangement of Mn atoms extending from the HOPG surface due to hydrogen bonding of the quinonoid complexes. We also showed that the topology of metal atoms on the surface could be controlled through the use of quinonoid metal complexes. A quinonoid

  2. Ytterbium Coordination Polymer with Four Different Coordination Numbers:The First Structural Characterization of Lanthanide Phthalate Complex

    Institute of Scientific and Technical Information of China (English)

    万永红; 金林培; 等

    2002-01-01

    The novel ytterbium coordination polymer is a t4wo-dimensional framework in which the central metal ions have four different coordination numbers and form four kinds of coordination poly-hedra,The four kinds of coordination polyhedra connect into infinite chains by sharing oxygen atoms.

  3. Detecting coordinated regulation of multi-protein complexes using logic analysis of gene expression

    Directory of Open Access Journals (Sweden)

    Yeates Todd O

    2009-12-01

    Full Text Available Abstract Background Many of the functional units in cells are multi-protein complexes such as RNA polymerase, the ribosome, and the proteasome. For such units to work together, one might expect a high level of regulation to enable co-appearance or repression of sets of complexes at the required time. However, this type of coordinated regulation between whole complexes is difficult to detect by existing methods for analyzing mRNA co-expression. We propose a new methodology that is able to detect such higher order relationships. Results We detect coordinated regulation of multiple protein complexes using logic analysis of gene expression data. Specifically, we identify gene triplets composed of genes whose expression profiles are found to be related by various types of logic functions. In order to focus on complexes, we associate the members of a gene triplet with the distinct protein complexes to which they belong. In this way, we identify complexes related by specific kinds of regulatory relationships. For example, we may find that the transcription of complex C is increased only if the transcription of both complex A AND complex B is repressed. We identify hundreds of examples of coordinated regulation among complexes under various stress conditions. Many of these examples involve the ribosome. Some of our examples have been previously identified in the literature, while others are novel. One notable example is the relationship between the transcription of the ribosome, RNA polymerase and mannosyltransferase II, which is involved in N-linked glycan processing in the Golgi. Conclusions The analysis proposed here focuses on relationships among triplets of genes that are not evident when genes are examined in a pairwise fashion as in typical clustering methods. By grouping gene triplets, we are able to decipher coordinated regulation among sets of three complexes. Moreover, using all triplets that involve coordinated regulation with the ribosome

  4. Determination of tetracycline in milk by using nucleotide/lanthanide coordination polymer-based ternary complex.

    Science.gov (United States)

    Tan, Hongliang; Ma, Chanjiao; Song, Yonghai; Xu, Fugang; Chen, Shouhui; Wang, Li

    2013-12-15

    The meta-organic coordination polymers have been emerged as fascinating nanomaterials because of their tunable nature. In this work, we employed lanthanide coordination polymer self-assembled from adenosine monophosphate (AMP) and europium ion (Eu(3+)) as receptor reagent and citrate (Cit) as ancillary ligand to construct a fluorescent sensor for the detection of tetracycline (Tc) in milk. The co-coordination of Cit and Tc with Eu(3+) on the surface of the coordination polymer AMP/Eu leads to the formation of ternary complex which emitted strong fluorescence due to the removal of coordinated water molecules and an intramolecular energy transfer from Tc to Eu(3+). The fluorescent intensity of Eu(3+) displayed a good linear response to Tc concentrations in the range of 0.1-20 μM with a detection limit of 60 nM. This method was successfully applied to determine the levels of Tc in milk, which is the first application of coordination polymer as a fluorescent sensor in real sample. Compared with other Eu(3+)-based fluorescent methods for Tc detection, the presented method allows simple, direct analysis of Tc without requiring special reaction media or complicated prepreparation processes. This straightforward strategy could be extended to the preparation of other lanthanide coordination polymer-based fluorescent probes for applications in biosensing, imaging, drug delivery, and so on.

  5. Electrochemically fabricated polypyrrole-cobalt-oxygen coordination complex as high-performance lithium-storage materials.

    Science.gov (United States)

    Guo, Bingkun; Kong, Qingyu; Zhu, Ying; Mao, Ya; Wang, Zhaoxiang; Wan, Meixiang; Chen, Liquan

    2011-12-23

    Current lithium-ion battery (LIB) technologies are all based on inorganic electrode materials, though organic materials have been used as electrodes for years. Disadvantages such as limited thermal stability and low specific capacity hinder their applications. On the other hand, the transition metal oxides that provide high lithium-storage capacity by way of electrochemical conversion reaction suffer from poor cycling stability. Here we report a novel high-performance, organic, lithium-storage material, a polypyrrole-cobalt-oxygen (PPy-Co-O) coordination complex, with high lithium-storage capacity and excellent cycling stability. Extended X-ray absorption fine structure and Raman spectroscopy and other physical and electrochemical characterizations demonstrate that this coordination complex can be electrochemically fabricated by cycling PPy-coated Co(3)O(4) between 0.0 V and 3.0 V versus Li(+)/Li. Density functional theory (DFT) calculations indicate that each cobalt atom coordinates with two nitrogen atoms within the PPy-Co coordination layer and the layers are connected with oxygen atoms between them. Coordination weakens the C-H bonds on PPy and makes the complex a novel lithium-storage material with high capacity and high cycling stability.

  6. Electrochemically fabricated polypyrrole-cobalt-oxygen coordination complex as high-performance lithium-storage materials.

    Science.gov (United States)

    Guo, Bingkun; Kong, Qingyu; Zhu, Ying; Mao, Ya; Wang, Zhaoxiang; Wan, Meixiang; Chen, Liquan

    2011-12-23

    Current lithium-ion battery (LIB) technologies are all based on inorganic electrode materials, though organic materials have been used as electrodes for years. Disadvantages such as limited thermal stability and low specific capacity hinder their applications. On the other hand, the transition metal oxides that provide high lithium-storage capacity by way of electrochemical conversion reaction suffer from poor cycling stability. Here we report a novel high-performance, organic, lithium-storage material, a polypyrrole-cobalt-oxygen (PPy-Co-O) coordination complex, with high lithium-storage capacity and excellent cycling stability. Extended X-ray absorption fine structure and Raman spectroscopy and other physical and electrochemical characterizations demonstrate that this coordination complex can be electrochemically fabricated by cycling PPy-coated Co(3)O(4) between 0.0 V and 3.0 V versus Li(+)/Li. Density functional theory (DFT) calculations indicate that each cobalt atom coordinates with two nitrogen atoms within the PPy-Co coordination layer and the layers are connected with oxygen atoms between them. Coordination weakens the C-H bonds on PPy and makes the complex a novel lithium-storage material with high capacity and high cycling stability. PMID:22127820

  7. A Mobile Care Coordination System for the Management of Complex Chronic Disease.

    Science.gov (United States)

    Haynes, Sarah; Kim, Katherine K

    2016-01-01

    There is global concern about healthcare cost, quality, and access as the prevalence of complex and chronic diseases, such as heart disease, continues to grow. Care for patients with complex chronic disease involves diverse practitioners and multiple transitions between medical centers, physician practices, clinics, community resources, and patient homes. There are few systems that provide the flexibility to manage these varied and complex interactions. Participatory and user-centered design methodology was applied to the first stage of building a mobile platform for care coordination for complex, chronic heart disease. Key informant interviews with patients, caregivers, clinicians, and care coordinators were conducted. Thematic analysis led to identification of priority user functions including shared care plan, medication management, symptom management, nutrition, physical activity, appointments, personal monitoring devices, and integration of data and workflow. Meaningful stakeholder engagement contributes to a person-centered system that enhances health and efficiency.

  8. Highly dynamic coordination behavior of Pn ligand complexes towards "naked" Cu(+) cations.

    Science.gov (United States)

    Fleischmann, Martin; Welsch, Stefan; Peresypkina, Eugenia V; Virovets, Alexander V; Scheer, Manfred

    2015-10-01

    Reactions of Cu(+) containing the weakly coordinating anion [Al{OC(CF3 )3 }4 ](-) with the polyphosphorus complexes [{CpMo(CO)2 }2 (μ,η(2) :η(2) -P2 )] (A), [CpM(CO)2 (η(3) -P3 )] (M=Cr(B1), Mo (B2)), and [Cp*Fe(η(5) -P5 )] (C) are presented. The X-ray structures of the products revealed mononuclear (4) and dinuclear (1, 2, 3) Cu(I) complexes, as well as the one-dimensional coordination polymer (5 a) containing an unprecedented [Cu2 (C)3 ](2+) paddle-wheel building block. All products are readily soluble in CH2 Cl2 and exhibit fast dynamic coordination behavior in solution indicated by variable temperature (31) P{(1) H} NMR spectroscopy.

  9. Thiosemicarbazone complexes of the platinum metals. A story of variable coordination modes

    Indian Academy of Sciences (India)

    Indrani Pal; Falguni Basuli; Samaresh Bhattacharya

    2002-08-01

    Salicylaldehyde thiosemicarbazone (H2saltsc) reacts with [M(PPh3)3X2] (M = Ru, Os; X = Cl, Br) to afford complexes of type [M(PPh3)2(Hsaltsc)2], in which the salicylaldehyde thiosemicarbazone ligand is coordinated to the metal as a bidentate N,S-donor forming a four-membered chelate ring. Reaction of benzaldehyde thiosemicarbazones (Hbztsc-R) with [M(PPh3)3X2] also affords complexes of similar type, viz. [M(PPh3)2(bztsc-R)2], in which the benzaldehyde thiosemicarbazones have also been found to coordinate the metal as a bidentate N,S-donor forming a fourmembered chelate ring as before. Reaction of the Hbztsc-R ligands has also been carried out with [M(bpy)2X2] (M = Ru, Os; X = Cl, Br), which has afforded complexes of type [M(bpy)2(bztsc-R)]+, which have been isolated as perchlorate salts. Coordination mode of bztsc-R has been found to be the same as before. Structure of the Hbztsc-OMe ligand has been determined and some molecular modelling studies have been carried out determine the reason for the observed mode of coordination. Reaction of acetone thiosemicarbazone (Hactsc) has then been carried out with [M(bpy)2X2] to afford the [M(bpy)2(actsc)]ClO4 complexes, in which the actsc ligand coordinates the metal as a bidentate N,S-donor forming a five-membered chelate ring. Reaction of H2saltsc has been carried out with [Ru(bpy)2Cl2] to prepare the [Ru(bpy)2(Hsaltsc)]ClO4 complex, which has then been reacted with one equivalent of nickel perchlorate to afford an octanuclear complex of type [{Ru(bpy)2(saltsc-H)}4Ni4](ClO4)4.

  10. Synthesis,Structure and Luminescent Properties of a Nine-Coordinated Praseodymium Complex

    Institute of Scientific and Technical Information of China (English)

    孙丽宁; 张洪杰; 符连社; 刘丰一; 孟庆国; 彭春耘; 于江波; 王淑彬

    2004-01-01

    The Pr(TTA)3phen(C2H5OH)quarternary complex with 2-thenoyltrifluoro-acetone(TTA), 1,10-phenanthroline(phen)and ethanol were synthesized and characterized by single-crystal X-ray diffraction. The central Pr3+ ion is nine-coordinated. The infrared(IR)spectrum, diffuse reflectance(DR)spectrum and fluorescence measurements of the complex were investigated.

  11. XAFS study of copper(II) complexes with square planar and square pyramidal coordination geometries

    Science.gov (United States)

    Gaur, A.; Klysubun, W.; Nitin Nair, N.; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

    2016-08-01

    X-ray absorption fine structure of six Cu(II) complexes, Cu2(Clna)4 2H2O (1), Cu2(ac)4 2H2O (2), Cu2(phac)4 (pyz) (3), Cu2(bpy)2(na)2 H2O (ClO4) (4), Cu2(teen)4(OH)2(ClO4)2 (5) and Cu2(tmen)4(OH)2(ClO4)2 (6) (where ac, phac, pyz, bpy, na, teen, tmen = acetate, phenyl acetate, pyrazole, bipyridine, nicotinic acid, tetraethyethylenediamine, tetramethylethylenediamine, respectively), which were supposed to have square pyramidal and square planar coordination geometries have been investigated. The differences observed in the X-ray absorption near edge structure (XANES) features of the standard compounds having four, five and six coordination geometry points towards presence of square planar and square pyramidal geometry around Cu centre in the studied complexes. The presence of intense pre-edge feature in the spectra of four complexes, 1-4, indicates square pyramidal coordination. Another important XANES feature, present in complexes 5 and 6, is prominent shoulder in the rising part of edge whose intensity decreases in the presence of axial ligands and thus indicates four coordination in these complexes. Ab initio calculations were carried out for square planar and square pyramidal Cu centres to observe the variation of 4p density of states in the presence and absence of axial ligands. To determine the number and distance of scattering atoms around Cu centre in the complexes, EXAFS analysis has been done using the paths obtained from Cu(II) oxide model and an axial Cu-O path from model of a square pyramidal complex. The results obtained from EXAFS analysis have been reported which confirmed the inference drawn from XANES features. Thus, it has been shown that these paths from model of a standard compound can be used to determine the structural parameters for complexes having unknown structure.

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

    Science.gov (United States)

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

    2016-01-19

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

  13. Spin crossover in Fe(II) complexes with N4S2 coordination

    DEFF Research Database (Denmark)

    Arroyave, Alejandra; Lennartson, Anders; Dragulescu-Andrasi, Alina;

    2016-01-01

    A systematic study of a series of Fe(II) complexes with the tetradentate N2S2-binding ligand and NCX− coligands (X = S, Se, BH3) conclusively demonstrates the occurrence of temperature-driven spin crossover (SCO), which is rarely observed for the Fe(II) ion in the N4S2 coordination environment...

  14. Chromogenic detection of Sarin by discolouring decomplexation of a metal coordination complex.

    Science.gov (United States)

    Ordronneau, Lucie; Carella, Alexandre; Pohanka, Miroslav; Simonato, Jean-Pierre

    2013-10-11

    An innovative chromogenic sensing concept based on decomplexation of a tris-(bipyridine)iron(II) coordination complex has been developed for the detection of organophosphorus nerve agents. It was evaluated both on a simulant and real Sarin in vapour and liquid phases.

  15. Synthesis and crystal structure of a wheel-shaped supramolecular coordination complex

    Indian Academy of Sciences (India)

    Deepak Gupta; Palanisamy Rajakannu; Bhaskaran Shankar; Firasat Hussain; Malaichamy Sathiyendiran

    2014-09-01

    Supramolecular coordination complex (SCC) possessing spatially arranged three anthraquinone dimers in a slipped-cofacial orientation was achieved by the treatment of Re2(CO)10, 2-hydroxymethylanthraquinone and tritopic N-donor via fac-Re(CO)3-directed one pot approach. The off-set -stacking and C≡O…H bonding interactions stabilize the ring structure.

  16. Experimental investigation of some coordination complexes using the sup(151)Eu Moessbauer resonance

    International Nuclear Information System (INIS)

    Several Schiff base complexes containing Eu151 metal ions have been synthesized and their Moessbauer spectra are recorded using the constant acceleration velocity spectrometer. The least-square analysis method for the evaluation of the hyperfine field coupling constants is adopted using the computer dec system-10. From the systematic analysis of the quadrupole coupling constants (q.c.c.) and isomer shifts it has been established that the coordination number of the metal ion of Bis(acetylacetone) benzidine and thiourea complexes is five, that of bis-vanillin benzidine and bis-salicylaldehyde-o-dianisidine is six, and that of bis-vanillin-o-phenylene diamine is seven. It is also found that the q.c.c. being negative in all these complexes decreases monotonically as the coordination number increases. One unusual aspect of this experimental data is that most of the coordination complexes have very low f-factors whereas the Schiff base complexes studied here have a fairly high recoilless fractions. Attempts are in progress to synthesize and study the Fe Schiff base complexes in place of Eu. (auth.)

  17. Coordination chemistry of amine bis(phenolate) titanium complexes: tuning complex type and structure by ligand modification.

    Science.gov (United States)

    Tshuva, E Y; Goldberg, I; Kol, M; Goldschmidt, Z

    2001-08-13

    The coordination chemistry of titanium(IV) complexes of amine bis(phenolate) ligands was investigated by synthesizing various types of complexes and analyzing them specroscopically and structurally. Steric effects of tridentate [ONO]- and tetradentate [ONNO]-type ligands were studied by reacting the ligand precursors with titanium tetra(isopropoxide). [ONNO]-type ligands featuring an amine donor located on a pendant arm led to octahedral bis(isopropoxide) complexes, regardless of the steric bulk around the metal. Several such complexes having varying steric crowding were thus synthesized. On the other hand, steric effects were found to play a major role in determining the complex constitution when [ONO]-type ligands, featuring no side donor, were involved. Relatively sterically undemanding ligands led to octahedral bis(homoleptic) complexes, whereas increased steric bulk resulted in the formation of pentacoordinate bis(isopropoxide) complexes. These pentacoordinate complexes readily lead to bis(heteroleptic) complexes by reaction with nonsterically demanding [ONO]- and [ONNO]-type ligand precursors. In the latter case the sidearm nitrogen remains uncoordinated to the metal. The bis(isopropoxide) complexes of the [ONNO]-type ligands may also lead to bis(heteroleptic) complexes, however, these reactions are much slower. PMID:11487331

  18. Care coordination for patients with complex health profiles in inpatient and outpatient settings.

    Science.gov (United States)

    Berry, Leonard L; Rock, Beth L; Smith Houskamp, Beth; Brueggeman, Joan; Tucker, Lois

    2013-02-01

    Patients with the most complex health profiles consume a disproportionate percentage of health care expenditures, yet often receive fragmented, suboptimal care. Since 2003, Wisconsin-based Gundersen Health has improved the quality of life and reduced the cost burden of patients with complex health profiles with an integrated care coordination program. Those results are consistent with data from the most successful care coordination demonstration projects funded by the Centers for Medicare and Medicaid Services. Specifically, Gundersen's program has been associated with reduced hospital stays, lower costs for inpatients, less use of inpatient services, and increased patient satisfaction. Gundersen's success is rooted in its team-based approach to coordinated care. Teams, led by a subspecialty-trained nurse, have regular, face-to-face contact with patients and their physicians in both inpatient and outpatient settings; involve patients deeply in care-related decisions; access a system-wide electronic medical record database that tracks patients' care; and take a macrolevel view of care-related factors and costs. Gundersen's model offers specific take-home lessons for institutions interested in coordinated care as they design programs aimed at improving quality and lowering costs. This institutional case study provides a window into well-executed care coordination at a large health care system in an era when major changes in health care provision and reimbursement mechanisms are on the horizon.

  19. FROM MANUFACTURING SCHEDULING TO SUPPLY CHAIN COORDINATION:THE CONTROL OF COMPLEXITY AND UNCERTAINTY

    Institute of Scientific and Technical Information of China (English)

    Peter B. LUH; Weidong FENG

    2003-01-01

    With time-based competition and rapid technology advancements, effective manufacturing scheduling and supply chain coordination are critical to quickly respond to changing market conditions. These problems, however, are difficult in view of inherent complexity and various uncertainties involved. Based on a series of results by the authors, decomposition and coordination by using Lagrangian relaxation is identified in this paper as an effective way to control complexity and uncertainty. A manufacturing scheduling problem is first formulated within the job shop context with uncertain order arrivals, processing times, due dates, and part priorities as a separable optimization problem. A solution methodology that combines Lagrangian relaxation, stochastic dynamic programming, and heuristics is developed. Method improvements to effectively solve large problems are also highlighted. To extend manufacturing scheduling within a factory to coordinate autonomic members across chains of suppliers, a decentralized supply chain model is established in the second half of this paper. By relaxing cross-member constraints, the model is decomposed into member-wise subproblems, and a nested optimization structure is developed based on the job shop scheduling results. Coordination is performed through the iterative updating of cross-member prices without accessing other members' private information or intruding their decision-making authorities, either with or without a coordinator. Two examples are presented to demonstrate the effectiveness of the method. Future prospects to overcome problem inseparability and improve computing efficiency are then discussed.

  20. The Role of Care Coordinator for Children with Complex Care Needs: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Rowan Hillis

    2016-05-01

    Full Text Available Introduction: This systematic review seeks to identify the intended components of the role of care coordinator for children with complex care needs and the factors that determine its composition in practice. Theory and methods: The initial search identified 1,157 articles, of which 37 met the inclusion criteria. They were quality assessed using the SIGN hierarchy of evidence structure. Results: Core components of the role include: coordination of care needs, planning and assessment, specialist support, emotional support, administration and logistics and continuing professional development. Influencing factors on the role include the external environment (political and socio-economic, the internal environment (organisational structure and funding protocols, the skills, qualifications and experience of the coordinator, the family circumstances and the nature of the interaction between the care coordinator and the family. Discussion: The lack of consistent terminology creates challenges and there is a need for greater consensus on this issue. Organisations and healthcare professionals need to recognise the extent to which contextual factors influence the role of a care coordinator in practice and plan accordingly. Despite evidence that suggests that the role is pivotal in ensuring that care needs are sustained, there remains great variability in the understanding of the role of a care coordinator for this population. Conclusions: As the provision of care increasingly moves closer to home there is a need for greater understanding of the nature and composition of the interaction between care coordinators and families to determine the extent to which appropriate services are being provided. Further work in this area should take into consideration any potential variance in service provision, for example any potential inequity arising due to geographic location. It is also imperative, where appropriate, to seek the views of children with complex care

  1. Flaviviral Replication Complex: Coordination between RNA Synthesis and 5'-RNA Capping.

    Science.gov (United States)

    Klema, Valerie J; Padmanabhan, Radhakrishnan; Choi, Kyung H

    2015-08-13

    Genome replication in flavivirus requires (-) strand RNA synthesis, (+) strand RNA synthesis, and 51-RNA capping and methylation. To carry out viral genome replication, flavivirus assembles a replication complex, consisting of both viral and host proteins, on the cytoplasmic side of the endoplasmic reticulum (ER) membrane. Two major components of the replication complex are the viral non-structural (NS) proteins NS3 and NS5. Together they possess all the enzymatic activities required for genome replication, yet how these activities are coordinated during genome replication is not clear. We provide an overview of the flaviviral genome replication process, the membrane-bound replication complex, and recent crystal structures of full-length NS5. We propose a model of how NS3 and NS5 coordinate their activities in the individual steps of (-) RNA synthesis, (+) RNA synthesis, and 51-RNA capping and methylation.

  2. Evolutionary dynamics of the traveler's dilemma and minimum-effort coordination games on complex networks.

    Science.gov (United States)

    Iyer, Swami; Killingback, Timothy

    2014-10-01

    The traveler's dilemma game and the minimum-effort coordination game are social dilemmas that have received significant attention resulting from the fact that the predictions of classical game theory are inconsistent with the results found when the games are studied experimentally. Moreover, both the traveler's dilemma and the minimum-effort coordination games have potentially important applications in evolutionary biology. Interestingly, standard deterministic evolutionary game theory, as represented by the replicator dynamics in a well-mixed population, is also inadequate to account for the behavior observed in these games. Here we study the evolutionary dynamics of both these games in populations with interaction patterns described by a variety of complex network topologies. We investigate the evolutionary dynamics of these games through agent-based simulations on both model and empirical networks. In particular, we study the effects of network clustering and assortativity on the evolutionary dynamics of both games. In general, we show that the evolutionary behavior of the traveler's dilemma and minimum-effort coordination games on complex networks is in good agreement with that observed experimentally. Thus, formulating the traveler's dilemma and the minimum-effort coordination games on complex networks neatly resolves the paradoxical aspects of these games.

  3. A Stable Coordination Complex of Rh(IV) in an N,O-Donor Environment.

    Science.gov (United States)

    Sinha, Shashi B; Shopov, Dimitar Y; Sharninghausen, Liam S; Vinyard, David J; Mercado, Brandon Q; Brudvig, Gary W; Crabtree, Robert H

    2015-12-23

    We describe facial and meridional isomers of [Rh(III)(pyalk)3], as well as meridional [Rh(IV)(pyalk)3](+) {pyalk =2-(2-pyridyl)-2-propanoate}, the first coordination complex in an N,O-donor environment to show a clean, reversible Rh(III/IV) redox couple and to have a stable Rh(IV) form, which we characterize by EPR and UV-visible spectroscopy as well as X-ray crystallography. The unprecedented stability of the Rh(IV) species is ascribed to the exceptional donor strength of the ligands, their oxidation resistance, and the meridional coordination geometry.

  4. Low complexity non-iterative coordinated beamforming in 2-user broadcast channels

    KAUST Repository

    Park, Kihong

    2010-10-01

    We propose a new non-iterative coordinated beamforming scheme to obtain full multiplexing gain in 2-user MIMO systems. In order to find the beamforming and combining matrices, we solve a generalized eigenvector problem and describe how to find generalized eigenvectors according to the Gaussian broadcast channels. Selected simulation results show that the proposed method yields the same sum-rate performance as the iterative coordinated beamforming method, while maintaining lower complexity by non-iterative computation of the beamforming and combining matrices. We also show that the proposed method can easily exploit selective gain by choosing the best combination of generalized eigenvectors. © 2006 IEEE.

  5. Ion-polyether coordination complexes: crystalline ionic conductors for clean energy storage.

    Science.gov (United States)

    Bruce, Peter G

    2006-03-21

    Ion-polyether complexes are the solid state analogues of crown ether and cryptand complexes. They represent a fascinating class of coordination compounds in their own right, with the ability to support ionic conductivity and the potential to be used as electrolytes in all-solid-state rechargeable lithium batteries. Here the recent discovery of ionic conductivity in crystalline ion-polyether complexes, when for 30 years such materials were considered to be insulators, is described, along with their closely related structural chemistry. PMID:16518503

  6. Crystal Structure and Characterization of a New Eight Coordinated Cadmium Complex

    Energy Technology Data Exchange (ETDEWEB)

    Hakimi, Mohammad; Moeini, Keyvan; Mardani, Zahra; Khorrami, Farzaneh [Payame Noor Univ., Tehran (Iran, Islamic Republic of)

    2013-06-15

    In this work, a new cadmium complex [Cd(L)(CH{sub 3}COO){sub 2}]-2H{sub 2}O (1) with the ligand L, N,N'-bis(2-pyridinecar-boxalidene)-1,2-cyclohexanediamine was prepared and identified by elemental analysis, FT-IR, Raman, {sup 1}H NMR spectroscopy and single-crystal X-ray diffraction. The cadmium atom in the crystal structure of 1 has distorted triangular dodecahedral geometry by coordination of the four nitrogen atoms of L and four oxygen atoms of the two acetate ions. Two water molecules are also incorporated in the crystal network. The O-H···O hydrogen bonds present in the crystal structure of 1. In this work, three structural surveys including coordination numbers of the cadmium atom, coordination modes of L and resonance in pyridine-2-ylmethanimine-based compounds are presented.

  7. Social dilemmas and individual/group coordination strategies in a complex rural land-use game

    Directory of Open Access Journals (Sweden)

    Luis García-Barrios

    2011-09-01

    Full Text Available Strengthening ongoing bottom-up capacity building processes for local and sustainable landscape-level governance is a multi-dimensional social endeavor. One of the tasks involved – participatory rural land use planning – requires more understanding and more awareness among all stakeholders regarding the social dilemmas local people confront when responding to each other’s land-use decisions. In this paper we will analyze and discuss a version of our game SIERRA SPRINGS that is simple to play for any stakeholder that can count to 24, yet entails a complex-coordination land use game – with an extensive and yet finite set of solutions – which can mimic in a stylized form some of the dilemmas landowners could confront in a landscape planning process where there livelihoods are at stake. The game has helped researchers and players observe and reflect on the individual coordination strategies that emerge within a group in response to these stylized dilemmas. This paper (1 develops a game-theoretical approach to cooperation, competition and coordination of land uses in small rural watersheds, (2 describe the goal, rules and mechanics of the game, (3 analyzes the structure of each farms’ solution set vs. the whole watershed’s solution set, (4 derives from them the coordination dilemmas and the risk of coordination failure, (5 describes four individual coordination strategies consistently displayed by players; mapping them in a plane we have called Group-Level Coordination Space, and (6 discusses the strengths, limitations and actual and potential uses of the game both for research and as an introductory tool for stakeholders involved in participatory land use planning.

  8. An europium(III) diglycolamide complex: insights into the coordination chemistry of lanthanides in solvent extraction.

    Science.gov (United States)

    Antonio, Mark R; McAlister, Daniel R; Horwitz, E Philip

    2015-01-14

    The synthesis, stoichiometry, and structural characterization of a homoleptic, cationic europium(III) complex with three neutral tetraalkyldiglycolamide ligands are reported. The tri(bismuth tetrachloride)tris(N,N,N',N'-tetra-n-octyldiglycolamide)Eu salt, [Eu(TODGA)3][(BiCl4)3] obtained from methanol was examined by Eu L3-edge X-ray absorption spectroscopy (XAS) to reveal an inner-sphere coordination of Eu(3+) that arises from 9 O atoms and two next-nearest coordination spheres that arise from 6 carbon atoms each. A structural model is proposed in which each TODGA ligand with its O=Ca-Cb-O-Cb-Ca=O backbone acts as a tridentate O donor, where the two carbonyl O atoms and the one ether O atom bond to Eu(3+). Given the structural rigidity of the tridentate coordination motif in [Eu(TODGA)3](3+) with six 5-membered chelate rings, the six Eu-Ca and six Eu-Cb interactions are readily resolved in the EXAFS (extended X-ray absorption fine structure) spectrum. The three charge balancing [BiCl4](-) anions are beyond the cationic [Eu(TODGA)3](3+) cluster in an outer sphere environment that is too distant to be detected by XAS. Despite their sizeable length and propensity for entanglement, the four n-octyl groups of each TODGA (for a total of twelve) do not perturb the Eu(3+) coordination environment over that seen from previously reported single-crystal structures of tripositive lanthanide (Ln(3+)) complexes with tetraalkyldiglycolamide ligands (of the same 1:3 metal-to-ligand ratio stoichiometry) but having shorter i-propyl and i-butyl groups. The present results set the foundation for understanding advanced solvent extraction processes for the separation of the minor, tripositive actinides (Am, Cm) from the Ln(3+) ions in terms of the local structure of Eu(3+) in a solid state coordination complex with TODGA.

  9. Prebiotic coordination chemistry: The potential role of transition-metal complexes in the chemical evolution

    Science.gov (United States)

    Beck, M.

    1979-01-01

    In approaching the extremely involved and complex problem of the origin of life, consideration of the coordination chemistry appeared not only as a possibility but as a necessity. The first model experiments appear to be promising because of prebiotic-type synthesis by means of transition-metal complexes. It is especially significant that in some instances various types of vitally important substances (nucleic bases, amino acids) are formed simultaneously. There is ground to hope that systematic studies in this field will clarify the role of transition-metal complexes in the organizatorial phase of chemical evolution. It is obvious that researchers working in the fields of the chemistry of cyano and carbonyl complexes, and of the catalytic effect of transition-metal complexes are best suited to study these aspects of the attractive and interesting problem of the origin of life.

  10. Coordination diversity of new mononucleating hydrazone in 3d metal complexes: Synthesis, characterization and structural studies

    Directory of Open Access Journals (Sweden)

    RAJESH S. BALIGAR

    2006-12-01

    Full Text Available The mononucleating hydrazone ligand LH3, a condensation product of salicyloylhydrazine and (2-formylphenoxyacetic acid, was synthesized and its coordination behavior with first row transition metal(II ions was investigated by isolating and elucidating the structure of the complexes using elemental analysis, conductivity and magnetic susceptibility measurements, as well as IR, 1H-NMR, electronic and EPR spectral techniques. The ligand forms mononuclear metal(II complexes of the type [CoLH(H2O2], [NiLH(H2O2, [CuLH] and [ZnLH]. The ligand field parameters, Dq, B and b values, in the case of the cobalt and nickel complexes support not only the octahedral geometry around the metal ion, but also imply the covalent nature of the bonding in the complexes. The EPR study revealed the presence of a spin exchange interaction in the solid copper complex and the covalent nature of the bonding. The 1H-NMR study of the zinc(II complex indicated the non-involvement of the COOH group in the coordination. The physico-chemical study supports for the presence of octahedral geometry around cobalt(II, nickel(II and tetrahedral geometry around copper(II and zinc(II ions.

  11. Synthesis, characterization and photochemistry of a new heptamolybdate supported magnesium-aqua coordination complex

    Indian Academy of Sciences (India)

    Savita S Khandolkar; Pallepogu Raghavaiah; Bikshandarkoil R Srinivasan

    2015-09-01

    The synthesis, crystal structure, redox characteristics and photochemistry of a new heptamolyb-date supported magnesium-aqua coordination complex viz. (hmtH)2 [{Mg(H2O)5}2 {Mo7O24}]·3H2O 1 (hmt = hexamethylenetetramine) is reported. The cyclic voltammogram reveals quasireversible redox behaviour while the degradation of rhodamine B (RhB) by 1 under sunlight irradiation indicates its photocatalytic activity. In the crystal structure of 1, two [Mg(H2O)5]2+ units are linked by a 2-bridging bidentate hepta-molybdate ligand resulting in a heptamolybdate supported magnesium-aqua coordinated dianionic complex [{Mg(H2O)5}2 {Mo7O24}]2− charge balanced by two (hmtH)+ cations. The cations, anions and the lattice water molecules are linked by several hydrogen bonding interactions.

  12. Using Learning Automata in Coordination Among Heterogeneous Agents in a Complex Multi-Agent Domain

    OpenAIRE

    Mohammadreza Khojasteh; Aida Kazimi

    2012-01-01

    This paper describes our use of Learning Automata as a reinforcement learning method in coordination among three heterogeneous teams of agents acting in RoboCup Rescue Simulation environment. We provide a brief introduction to Learning Automata and Cellular Learning Automata, the reinforcement machine learning methods that we have used in lots of parts of our agents’ development. Then we will describe the major challenges each team of agents should be concerned about in such a complex domain ...

  13. Fluorescent zinc-terpyridine complex containing coordinated peroxo counter ion in aqueous medium

    Indian Academy of Sciences (India)

    S Kapoor; M S Sastry

    2000-08-01

    We describe a mixed ligand-zinc (10) complex containing coordinated peroxo ion and 2,2'2"-terpyridine and exhibiting fluorescence in the visible region (473 nm) on excitation at 390 nm in aqueous medium at room temperature. We also discuss the unusual phenomenon of enhancement of this fluorescence intensity on addition of some transition metal ions (35, 310, 40 and 39 electronic configurations).

  14. Dipyridylamide ligand dependent dimensionality in luminescent zinc 2,4-pyridinedicarboxylate coordination complexes

    Science.gov (United States)

    Wudkewych, Megan J.; LaDuca, Robert L.

    2016-09-01

    Zinc nitrate, 2,4-pyridinedicarboxylic acid (2,4-pdcH2), and a hydrogen-bonding capable dipyridylamide ligand were combined in aqueous solution and subjected to hydrothermal reaction conditions. Three new crystalline coordination complexes were generated; their dimensionality depends crucially on the dipyridylamide length and geometric disposition of the pyridyl nitrogen donors. The three new phases were structurally characterized via single-crystal X-ray diffraction. {[H23-pina][Zn(2,4-pdc)2(H2O)2]·H2O} (1, 3-pina = 3-pyridylisonicotinamide) is a salt with protonated dipyridylamide cations and coordination complex anions. {[Zn2(2,4-pdc)2(H2O)4(3-pna)]·3H2O}n (2, 3-pna = 3-pyridylnicotinamide) shows a system of two-fold interpenetrated ruffled (6,3) coordination polymer layers. {[Zn(2,4-pdc)(H2O)2(3-pmna)]n (3, 3-pmna = 3-pyridylmethylnicotinamide) manifests a simple 1D chain topology. Luminescence was observed for two of the zinc complexes; this behavior is attributed to π-π* or π-n molecular orbital transitions. Thermal decomposition properties of the new phases are also probed.

  15. The DREAM complex: master coordinator of cell cycle-dependent gene expression.

    Science.gov (United States)

    Sadasivam, Subhashini; DeCaprio, James A

    2013-08-01

    The dimerization partner, RB-like, E2F and multi-vulval class B (DREAM) complex provides a previously unsuspected unifying role in the cell cycle by directly linking p130, p107, E2F, BMYB and forkhead box protein M1. DREAM mediates gene repression during the G0 phase and coordinates periodic gene expression with peaks during the G1/S and G2/M phases. Perturbations in DREAM complex regulation shift the balance from quiescence towards proliferation and contribute to the increased mitotic gene expression levels that are frequently observed in cancers with a poor prognosis. PMID:23842645

  16. Flexible and Asymmetric Ligand in Constructing Coordinated Complexes: Synthesis, Crystal Structures and Fluorescent Characterization

    Directory of Open Access Journals (Sweden)

    Jianhua Lin

    2010-12-01

    Full Text Available Flexible and asymmetric ligand L [L = 1-((pyridin-3-ylmethyl-1H-benzotriazole], is used as a basic backbone to construct complicated metal-organic frameworks. Two new polymers, namely, [Ag2(L2(NO32]n (1 and [Ag(L(ClO4]n (2, were synthesized and characterized by X-ray structure analysis and fluorescent spectroscopy. The complex 1 gives an “S” type double helical conformation, whereas complex 2 exhibits a 1D zigzag configuration. Different anions affect the silver coordination geometry and crystal packing topology.

  17. Coordination Structure Conversion of Hydrazone-Palladium(II) Complexes in the Solid State and in Solution.

    Science.gov (United States)

    Kitamura, Fumi; Sawaguchi, Kana; Mori, Asami; Takagi, Shoji; Suzuki, Takayoshi; Kobayashi, Atsushi; Kato, Masako; Nakajima, Kiyohiko

    2015-09-01

    We prepared hydrazone-palladium(II) complexes of [PdCl2(HL(n))] and [PdCl(L(n))] (n = 1-3) by the reaction of [PdCl2(cod)] or [PdCl2(PhCN)2] and the hydrazone ligands of HL(n) {N'-(pyridin-2-ylmethylene)picolinohydrazide (HL(1)), N'-[1-(pyridin-2-yl)ethylidene]picolinohydrazide (HL(2)), and N'-[(6-methylpyridin-2-yl)methylene]picolinohydrazide (HL(3))}. The structures of the complexes were determined by X-ray analysis. The hydrazone ligands had κN(py1),κN(imine) and κN(amidate),κN(py2) bidentate coordination modes in [PdCl2(HL(n))] (1, n = 1; 2, n = 2) and in [PdCl2(HL(3))] (3), respectively. In contrast, tridentate coordination modes of κN(py1),κN(imine),κN(py2) and κN(py1),κN(amidate),κN(py2) were observed in [PdCl(L(n))] (4, n = 1; 5, n = 2) and in [PdCl(L(n))] (6, n = 1; 7, n = 2; 8, n = 3). Thermal conversion of complexes 1-3 to complexes 6-8 proceeded in acetonitrile. Complexes 4 and 5 were obtained from complexes 1 and 2, respectively, in a basic acetonitrile solution under dark conditions. Complex 4 reverted immediately to complex 1 in an acidic acetonitrile solution that included hydrochloric acid. However, under room light, in the basic acetonitrile solution that included trimethylamine, complex 4 converted photochemically to complex 6. The thermochromic or vapochromic structure conversion of these complexes also occurred in the solid state. On heating at 180 °C, the color of the crystals of complexes 1, 2, and 3 changed from yellow to orange in the solid state. (1)H NMR and/or UV-vis absorption spectroscopy confirmed that the orange complexes 6-8 were produced. The reddish-orange crystals of complexes 4 and 5 were exposed to hydrogen chloride vapor to yield the yellow products of complexes 1 and 2, respectively. PMID:26305775

  18. Control of Lanthanide Coordination Environment: Synthesis, Structure, and Oxygen-Sensitive Luminescence Properties of an Eight-Coordinate Tb(III) Complex.

    Science.gov (United States)

    Nakai, Hidetaka; Seo, Juncheol; Kitagawa, Kazuhiro; Goto, Takahiro; Nonaka, Kyoshiro; Matsumoto, Takahiro; Ogo, Seiji

    2016-07-01

    Coordination environment of the Tb(3+) ion in oxygen-sensitive luminescent complexes can be successfully controlled through the size of alkyl substituents on ligands {((RMe)ArOH)4cyclen} (R = tBu or Me; cyclen = 1,4,7,10-tetraazacyclododecane); a newly prepared eight-coordinate complex 1(tBu) shows higher oxygen sensitivity (KSV = 17 600) and lower luminescence quantum yield (Φ = 0.67 under N2) than those of the previously reported seven-coordinate analogues 1(Me) and [{((MeMe)ArO)3tacn}Tb(III)(THF)] (KSV = 12 600 and 8300, Φ = 0.91 and 0.91 under N2, respectively; tacn = 1,4,7-triazacyclononane; THF = tetrahydrofuran). The oxygen-sensitive mechanism is discussed on the basis of the photophysical properties of the corresponding Gd(III) complexes. PMID:27326826

  19. Coordination chemistry and reactivity of zinc complexes supported by a phosphido pincer ligand.

    Science.gov (United States)

    D'Auria, Ilaria; Lamberti, Marina; Mazzeo, Mina; Milione, Stefano; Roviello, Giuseppina; Pellecchia, Claudio

    2012-02-20

    The preparation and characterization of new Zn(II) complexes of the type [(PPP)ZnR] in which R = Et (1) or N(SiMe(3))(2) (2) and PPP is a tridentate monoanionic phosphido ligand (PPP-H = bis(2-diphenylphosphinophenyl)phosphine) are reported. Reaction of ZnEt(2) and Zn[N(SiMe(3))(2)](2) with one equivalent of proligand PPP-H produced the corresponding tetrahedral zinc ethyl (1) and zinc amido (2) complexes in high yield. Homoleptic (PPP)(2) Zn complex 3 was obtained by reaction of the precursors with two equivalents of the proligand. Structural characterization of 1-3 was achieved by multinuclear NMR spectroscopy ((1)H, (13)C, and (31)P) and X-ray crystallography (3). Variable-temperature (1)H and (31)P NMR studies highlighted marked flexibility of the phosphido pincer ligand in coordination at the metal center. A DFT calculation on the compounds provided theoretical support for this behavior. The activities of 1 and 2 toward the ring-opening polymerization of ε-caprolactone and of L- and rac-lactide were investigated, also in combination with an alcohol as external chain-transfer agent. Polyesters with controlled molecular parameters (M(n), end groups) and low polydispersities were obtained. A DFT study on ring-opening polymerization promoted by these complexes highlighted the importance of the coordinative flexibility of the ancillary ligand to promote monomer coordination at the reactive zinc center. Preliminary investigations showed the ability of these complexes to promote copolymerization of L-lactide and ε-caprolactone to achieve random copolymers whose microstructure reproduces the composition of the monomer feed.

  20. Ligand influences on properties of uranium coordination complexes. Structure, reactivity, and spectroscopy

    International Nuclear Information System (INIS)

    In this thesis several different aspects of uranium chemistry are presented. It was shown that terminal uranium(V) oxo and imido complexes [((RArO)3tacn)UV(O)] and [((RArO)3tacn)UV(NSiMe3)] (R = t Bu, Ad) can be oxidized by silver(I) hexafluoro-antimonate to the uranium(VI) oxo and imido complexes [((RArO)3tacn)UVI(O)]SbF6 and [((RArO)3tacn)UVI(NSiMe3)]SbF6. While for the t Bu-derivative of the oxo complex an equatorial coordination is observed due to stabilization by the inverse trans-influence, normal axial coordination is observed for the Ad-derivative and both imido complexes. The inverse trans-influence was thus proven to be a key factor for the coordination mode of a terminal ligand on high valent uranium complexes. LIII XANES was shown to be a great tool for the determination of oxidation states of uranium complexes. Therefore, a series of uranium complexes in all stable oxidation states for uranium, +III to +VI was prepared, and their spectra analyzed. All compounds bear only O-donor ligands in addition to the chlating trisaryloxide-tacn-ligand. A separation of 1.5 to 3 eV in the white line energy is observed between the different oxidation states. This series can be used as reference for compounds, where oxidation state assignment is not obvious, such as a ketyl radical complex [((t-BuAr)O3tacn)U(O-C(t-BuPh)2.-)]. For this complex, the oxidation state of +IV could be assigned. Moreover, a series of isostructural uranium(IV) complexes was prepared. The influence of different ligands according to the spectrochemical series on the electronic and magnetic properties could be shown using UV/vis/NIR spectroscopy and variable temperature SQUID measurements. Calculations of uranium LIII XANES spectra show a variation in the shape of the spectra and thus high resolution PFY-XANES would be a great tool to determine the electronic influence of these different axial ligands. Using the single N-anchored ligand system, the first example of a uranium(IV)

  1. Coordination Nature of 4-Mercaptoaniline to Sn(II Ion: Formation of a One Dimensional Coordination Polymer and Its Decomposition to a Mono Nuclear Sn(IV Complex

    Directory of Open Access Journals (Sweden)

    Eon S. Burkett

    2014-12-01

    Full Text Available The coordination of the bifunctional ligand 4-mercaptoaniline with aqueo us tin(II metal ion was studied. A coordination polymer was synthesized when an aqueous solution of SnCl2 was treated with 4-MA. The crystalline material is stable under atmospheric conditions retaining its oxidation state. However, when submerged in a solution saturated with oxygen, the compound oxidizes to a mononuclear tin(IV complex. Both the compounds were characterized by single crystal X-ray diffraction studies. Although the structure of the tin(IV complex was previously reported, crystal structure of this compound was redetermined.

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

    Science.gov (United States)

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

    2003-07-01

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

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

    Science.gov (United States)

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

    2016-03-24

    The Huisgen thermal reaction between an organic azide and an acetylene was employed for the selective monofunctionalization of a X6 -azacryptand ligand bearing a tren coordinating unit [X6 stands for calix[6]arene and tren for tris(2-aminoethyl)amine]. Supramolecular assistance, originating from the formation of a host-guest inclusion complex between the reactants, greatly accelerates the reaction while self-inhibition affords a remarkable selectivity. The new ligand possesses a single amino-leg appended at the large rim of the calixarene core and the corresponding Zn(2+) complex was characterized both in solution and in the solid state. The coordination of Zn(2+) not only involves the tren cap but also the introverted amino-leg, which locks the metal ion in the cavity. Compared with the parent ligand deprived of the amino-leg, the affinity of the new monofunctionalized X6 tren ligand 6 for Zn(2+) is found to have a 10-fold increase in DMSO, which is a very competitive solvent, and with an enhancement of at least three orders of magnitude in CDCl3 /CD3 OD (1:1, v/v). In strong contrast with the fast binding kinetics, decoordination of Zn(2+) as well as transmetallation appeared to be very slow processes. The monofunctionalized X6 tren ligand 6 fully protects the metal ion from the external medium thanks to the combination of a cavity and a closed coordination sphere, leading to greater thermodynamic and kinetic stabilities. PMID:26916610

  4. Complexation of U(VI) with dipicolinic acid: thermodynamics and coordination modes.

    Science.gov (United States)

    Xu, Chao; Tian, Guoxin; Teat, Simon J; Rao, Linfeng

    2013-03-01

    Complexation of UO2(2+) with dipicolinic acid (DPA) has been investigated in 0.1 M NaClO4. The stability constants (log β1 and log β2) for two successive complexes, UO2L and UO2L2(2-) where L(2-) stands for the deprotonated dipicolinate anion, were determined to be 10.7 ± 0.1 and 16.3 ± 0.1 by spectrophotometry. The enthalpies of complexation (ΔH1 and ΔH2) were measured to be -(6.9 ± 0.2) and -(28.9 ± 0.5) kJ·mol(-1) by microcalorimetry. The entropies of complexation (ΔS1 and ΔS2) were calculated accordingly to be (181 ± 3) and (215 ± 4) J·K(-1)·mol(-1). The strong complexation of UO2(2+) with DPA is driven by positive entropies as well as exothermic enthalpies. The crystal structure of Na2UO2L2(H2O)8(s) shows that, in the 1:2 UO2(2+)/DPA complex, the U atom sits at a center of inversion and the two DPA ligands symmetrically coordinate to UO2(2+) via its equatorial plane in a tridentate mode. The structural information suggests that, due to the conjugated planar structure of DPA with the donor atoms (the pyridine nitrogen and two carboxylate oxygen atoms) arranged at optimal positions to coordinate with UO2(2+), little energy is required for the preorganization of the ligand, resulting in strong UO2(2+)/DPA complexation. PMID:23421621

  5. Axial Coordination and Conformational Heterogeneity of Nickel(II) Tetraphenylporphyrin Complexes with Nitrogenous Bases.

    Science.gov (United States)

    Jia, Song-Ling; Jentzen, Walter; Shang, Mayou; Song, Xing-Zhi; Ma, Jian-Guo; Scheidt, W. Robert; Shelnutt, John A.

    1998-08-24

    Axial ligation of nickel(II) 5,10,15,20-tetraphenylporphyrin (NiTPP) with pyrrolidine or piperidine has been investigated using X-ray crystallography, UV-visible spectroscopy, resonance Raman spectroscopy, and molecular mechanics (MM) calculations. By varying the pyrrolidine concentration in dichloromethane, distinct nu(4) Raman lines are found for the four-, five-, and six-coordinate species of NiTPP. The equilibrium constants for addition of the first and second pyrrolidine axial ligands are 1.1 and 3.8 M(-)(1), respectively. The axial ligands and their orientations influence the type and magnitude of the calculated nonplanar distortion. The differences in the calculated energies of the conformers having different ligand rotational angles are small so they may coexist in solution. Because of the similarity in macrocyclic structural parameters of these conformers and the free rotation of the axial ligands, narrow and symmetric nu(2) and nu(8) Raman lines are observed. Nonetheless, the normal-coordinate structural-decomposition analysis of the nonplanar distortions of the calculated structures and the crystal structure of the bis(piperidine) complex reveals a relationship between the orientations of axial ligand(s) and the macrocyclic distortions. For the five-coordinate complex with the plane of the axial ligand bisecting the Ni-N(pyrrole) bonds, a primarily ruffled deformation results. With the ligand plane eclipsing the Ni-N(pyrrole) bonds, a mainly saddled deformation occurs. With the addition of the second axial ligand, the small doming of the five-coordinate complexes disappears, and ruffling or saddling deformations change depending on the relative orientation of the two axial ligands. The crystal structure of the NiTPP bis(piperidine) complex shows a macrocycle distortion composed of wav(x) and wav(y) symmetric deformations, but no ruffling, saddling, or doming. The difference in the calculated and observed distortions results partly from the phenyl group

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-15

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

  7. Features of arsenic coordination in AsXn complexes (X=F, Cl, Br, I)

    International Nuclear Information System (INIS)

    Investigation into stoichiometry of F-, Cl-, Br-, and I-containing arsenic complexes was conducted using Voronoi-Dirichlet polyhedrons (VDP). Decrease of third-dimensional effect of unshared electron pairs of As(3) atoms is established as decrease of electronegativity of surrounding atom in the AsFn-AsCln-AsBrn-AsIn system. Method of interlaced spheres may be used for determination of coordination number of arsenic atoms in the crystal structure. Whatever oxidation degree of arsenic atoms and their coordination numbers common linear dependences between solid angles of VDP Ω grains and internuclear distances r(As-X) corresponding those grains are observed. For I-containing arsenic compounds the equilibrium Ω(As-I) = 40(1) - 8.1(3) r(As-I) { = -0.940.91 contact As-I} is employed

  8. Using Learning Automata in Coordination Among Heterogeneous Agents in a Complex Multi-Agent Domain

    Directory of Open Access Journals (Sweden)

    Mohammadreza Khojasteh

    2012-06-01

    Full Text Available This paper describes our use of Learning Automata as a reinforcement learning method in coordination among three heterogeneous teams of agents acting in RoboCup Rescue Simulation environment. We provide a brief introduction to Learning Automata and Cellular Learning Automata, the reinforcement machine learning methods that we have used in lots of parts of our agents’ development. Then we will describe the major challenges each team of agents should be concerned about in such a complex domain and for each challenge, we propose our approaches to develop cooperative teams. Finally, some results of using Learning Automata in coordinating these heterogeneous teams of agents that cooperate to mitigate the disastrous damages in a simulated city are evaluated.

  9. Hardware Implementation of a Modified Delay-Coordinate Mapping-Based QRS Complex Detection Algorithm

    Directory of Open Access Journals (Sweden)

    Andrej Zemva

    2007-01-01

    Full Text Available We present a modified delay-coordinate mapping-based QRS complex detection algorithm, suitable for hardware implementation. In the original algorithm, the phase-space portrait of an electrocardiogram signal is reconstructed in a two-dimensional plane using the method of delays. Geometrical properties of the obtained phase-space portrait are exploited for QRS complex detection. In our solution, a bandpass filter is used for ECG signal prefiltering and an improved method for detection threshold-level calculation is utilized. We developed the algorithm on the MIT-BIH Arrhythmia Database (sensitivity of 99.82% and positive predictivity of 99.82% and tested it on the long-term ST database (sensitivity of 99.72% and positive predictivity of 99.37%. Our algorithm outperforms several well-known QRS complex detection algorithms, including the original algorithm.

  10. Hardware Implementation of a Modified Delay-Coordinate Mapping-Based QRS Complex Detection Algorithm

    Directory of Open Access Journals (Sweden)

    Jager Franc

    2007-01-01

    Full Text Available We present a modified delay-coordinate mapping-based QRS complex detection algorithm, suitable for hardware implementation. In the original algorithm, the phase-space portrait of an electrocardiogram signal is reconstructed in a two-dimensional plane using the method of delays. Geometrical properties of the obtained phase-space portrait are exploited for QRS complex detection. In our solution, a bandpass filter is used for ECG signal prefiltering and an improved method for detection threshold-level calculation is utilized. We developed the algorithm on the MIT-BIH Arrhythmia Database (sensitivity of 99.82 and positive predictivity of 99.82 and tested it on the long-term ST database (sensitivity of 99.72 and positive predictivity of 99.37 . Our algorithm outperforms several well-known QRS complex detection algorithms, including the original algorithm.

  11. Functional cooperation between FACT and MCM is coordinated with cell cycle and differential complex formation

    Directory of Open Access Journals (Sweden)

    Lin Chih-Li

    2010-02-01

    Full Text Available Abstract Background Functional cooperation between FACT and the MCM helicase complex constitutes an integral step during DNA replication initiation. However, mode of regulation that underlies the proper functional interaction of FACT and MCM is poorly understood. Methods & Results Here we present evidence indicating that such interaction is coordinated with cell cycle progression and differential complex formation. We first demonstrate the existence of two distinct FACT-MCM subassemblies, FACT-MCM2/4/6/7 and FACT-MCM2/3/4/5. Both complexes possess DNA unwinding activity and are subject to cell cycle-dependent enzymatic regulation. Interestingly, analysis of functional attributes further suggests that they act at distinct, and possibly sequential, steps during origin establishment and replication initiation. Moreover, we show that the phosphorylation profile of the FACT-associated MCM4 undergoes a cell cycle-dependent change, which is directly correlated with the catalytic activity of the FACT-MCM helicase complexes. Finally, at the quaternary structure level, physical interaction between FACT and MCM complexes is generally dependent on persistent cell cycle and further stabilized upon S phase entry. Cessation of mitotic cycle destabilizes the complex formation and likely leads to compromised coordination and activities. Conclusions Together, our results correlate FACT-MCM functionally and temporally with S phase and DNA replication. They further demonstrate that enzymatic activities intrinsically important for DNA replication are tightly controlled at various levels, thereby ensuring proper progression of, as well as exit from, the cell cycle and ultimately euploid gene balance.

  12. Desymmetrization of an Octahedral Coordination Complex Inside a Self-Assembled Exoskeleton.

    Science.gov (United States)

    Johnstone, Mark D; Schwarze, Eike K; Ahrens, Jennifer; Schwarzer, Dirk; Holstein, Julian J; Dittrich, Birger; Pfeffer, Frederick M; Clever, Guido H

    2016-07-25

    The synthesis of a centrally functionalized, ribbon-shaped [6]polynorbornane ligand L that self-assembles with Pd(II) cations into a {Pd2 L4 } coordination cage is reported. The shape-persistent {Pd2 L4 } cage contains two axial cationic centers and an array of four equatorial H-bond donors pointing directly towards the center of the cavity. This precisely defined supramolecular environment is complementary to the geometry of classic octahedral complexes [M(XY)6 ] with six diatomic ligands. Very strong binding of [Pt(CN)6 ](2-) to the cage was observed, with the structure of the host-guest complex {[Pt(CN)6 ]@Pd2 L4 } supported by NMR spectroscopy, MS, and X-ray data. The self-assembled shell imprints its geometry on the encapsulated guest, and desymmetrization of the octahedral platinum species by the influence of the D4h -symmetric second coordination sphere was evidenced by IR spectroscopy. [Fe(CN)6 ](3-) and square-planar [Pt(CN)4 ](2-) were strongly bound. Smaller octahedral anions such as [SiF6 ](2-) , neutral carbonyl complexes ([M(CO)6 ]; M=Cr, Mo, W) and the linear [Ag(CN)2 ](-) anion were only weakly bound, showing that both size and charge match are key factors for high-affinity binding. PMID:27245358

  13. Desymmetrization of an Octahedral Coordination Complex Inside a Self-Assembled Exoskeleton.

    Science.gov (United States)

    Johnstone, Mark D; Schwarze, Eike K; Ahrens, Jennifer; Schwarzer, Dirk; Holstein, Julian J; Dittrich, Birger; Pfeffer, Frederick M; Clever, Guido H

    2016-07-25

    The synthesis of a centrally functionalized, ribbon-shaped [6]polynorbornane ligand L that self-assembles with Pd(II) cations into a {Pd2 L4 } coordination cage is reported. The shape-persistent {Pd2 L4 } cage contains two axial cationic centers and an array of four equatorial H-bond donors pointing directly towards the center of the cavity. This precisely defined supramolecular environment is complementary to the geometry of classic octahedral complexes [M(XY)6 ] with six diatomic ligands. Very strong binding of [Pt(CN)6 ](2-) to the cage was observed, with the structure of the host-guest complex {[Pt(CN)6 ]@Pd2 L4 } supported by NMR spectroscopy, MS, and X-ray data. The self-assembled shell imprints its geometry on the encapsulated guest, and desymmetrization of the octahedral platinum species by the influence of the D4h -symmetric second coordination sphere was evidenced by IR spectroscopy. [Fe(CN)6 ](3-) and square-planar [Pt(CN)4 ](2-) were strongly bound. Smaller octahedral anions such as [SiF6 ](2-) , neutral carbonyl complexes ([M(CO)6 ]; M=Cr, Mo, W) and the linear [Ag(CN)2 ](-) anion were only weakly bound, showing that both size and charge match are key factors for high-affinity binding.

  14. Talking about the institutional complexity of the integrated rehabilitation system – the importance of coordination

    Directory of Open Access Journals (Sweden)

    Sari Miettinen

    2013-03-01

    Full Text Available Rehabilitation in Finland is a good example of functions divided among several welfare sectors, such as health services and social services.  The rehabilitation system in Finland is a complex one and there have been many efforts to create a coordinated entity. The purpose of this study is to open up a complex welfare system at the upper policy level and to understand the meaning of coordination at the level of service delivery. We shed light in particular on the national rehabilitation policy in Finland and how the policy has tried to overcome the negative effects of institutional complexity. In this study we used qualitative content analysis and frame analysis. As a result we identified four different welfare state frames with distinct features of policy problems, policy alternatives and institutional failure. The rehabilitation policy in Finland seems to be divided into different components which may cause problems at the level of service delivery and thus in the integration of services. Bringing these components together could at policy level enable a shared view of the rights of different population groups, effective management of integration at the level of service delivery and also an opportunity for change throughout the rehabilitation system.

  15. The DREAM complex: Master coordinator of cell cycle dependent gene expression

    Science.gov (United States)

    Sadasivam, Subhashini; DeCaprio, James A.

    2014-01-01

    Preface The dimerization partner (DP), retinoblastoma (RB)-like, E2F and MuvB (DREAM) complex provides a previously unsuspected unifying role in the cell cycle by directly linking p130, p107, E2F, BMYB and FOXM1. DREAM mediates gene repression during G0 and coordinates periodic gene expression with peaks during G1/S and G2/M. Perturbations in DREAM regulation shift the balance from quiescence towards proliferation and contribute to increased mitotic gene expression levels frequently observed in cancers with poor prognosis. PMID:23842645

  16. The DREAM complex: Master coordinator of cell cycle dependent gene expression

    OpenAIRE

    Sadasivam, Subhashini; DeCaprio, James A.

    2013-01-01

    The dimerization partner (DP), retinoblastoma (RB)-like, E2F and MuvB (DREAM) complex provides a previously unsuspected unifying role in the cell cycle by directly linking p130, p107, E2F, BMYB and FOXM1. DREAM mediates gene repression during G0 and coordinates periodic gene expression with peaks during G1/S and G2/M. Perturbations in DREAM regulation shift the balance from quiescence towards proliferation and contribute to increased mitotic gene expression levels frequently observed in cance...

  17. Exploring chemical reactivity of complex systems with path-based coordinates: role of the distance metric.

    Science.gov (United States)

    Zinovjev, Kirill; Tuñón, Iñaki

    2014-09-01

    Path-based reaction coordinates constitute a valuable tool for free-energy calculations in complex processes. When a reference path is defined by means of collective variables, a nonconstant distance metric that incorporates the nonorthonormality of these variables should be taken into account. In this work, we show that, accounting for the correct metric tensor, these kind of variables can provide iso-hypersurfaces that coincide with the iso-committor surfaces and that activation free energies equal the value that would be obtained if the committor function itself were used as reaction coordinate. The advantages of the incorporation of the variable metric tensor are illustrated with the analysis of the enzymatic reaction catalyzed by isochorismate-pyruvate lyase. Hybrid QM/MM techniques are used to obtain the free energy profile and to analyze reactive trajectories initiated at the transition state. For this example, the committor histogram is peaked at 0.5 only when a variable metric tensor is incorporated in the definition of the path-based coordinate. PMID:24986052

  18. Exploring Coordination Modes: Late Transition Metal Complexes with a Methylene-bridged Macrocyclic Tetra-NHC Ligand.

    Science.gov (United States)

    Altmann, Philipp J; Weiss, Daniel T; Jandl, Christian; Kühn, Fritz E

    2016-05-20

    A tetranuclear silver(I) N-heterocyclic carbene (NHC) complex bearing a macrocyclic, exclusively methylene-bridged, tetracarbene ligand was synthesized and employed as transmetalation agent for the synthesis of nickel(II), palladium(II), platinum(II), and gold(I) derivatives. The transition metal complexes exhibit different coordination geometries, the coinage metals being bound in a linear fashion forming molecular box-type complexes, whereas the group 10 metals adapt an almost ideal square planar coordination geometry within the ligand's cavity, resulting in saddle-shaped complexes. Both the Ag(I) and the Au(I) complexes show ligand-induced metal-metal contacts, causing photoluminescence in the blue region for the gold complex. Distinct metal-dependent differences of the coordination behavior between the group 10 transition metals were elucidated by low-temperature NMR spectroscopy and DFT calculations. PMID:27017146

  19. An aqueous non-heme Fe(iv)oxo complex with a basic group in the second coordination sphere

    DEFF Research Database (Denmark)

    Vad, Mads Sørensen; Lennartson, Anders; Nielsen, Anne;

    2012-01-01

    The Fe(iv)oxo complex of a coordinatively flexible multidentate mono-carboxylato ligand is obtained by the one electron oxidation of a low spin Fe(iii) precursor in water.......The Fe(iv)oxo complex of a coordinatively flexible multidentate mono-carboxylato ligand is obtained by the one electron oxidation of a low spin Fe(iii) precursor in water....

  20. Synthesis and reactivity of a conveniently prepared two-coordinate bis(amido) nickel(II) complex.

    Science.gov (United States)

    Lipschutz, Michael I; Tilley, T Don

    2012-07-21

    A strictly two-coordinate nickel(II) bis(amido) complex has been prepared and its reactivity towards a variety of small molecules is described. Ni[N(SiMe(3))(DIPP)](2) reacts with DMAP and acetonitrile to form T-shaped three-coordinate complexes, and preliminary results show that Ni[N(SiMe(3))(DIPP)](2) is a catalyst for the hydrosilation of olefins with secondary silanes at ambient temperature.

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

    Science.gov (United States)

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

    2013-11-01

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

  2. Small molecule regulation of self-association and catalytic activity in a supramolecular coordination complex.

    Science.gov (United States)

    McGuirk, C Michael; Stern, Charlotte L; Mirkin, Chad A

    2014-03-26

    Herein, we report the synthesis and characterization of the first weak-link approach (WLA) supramolecular construct that employs the small molecule regulation of intermolecular hydrogen bonding interactions for the in situ control of catalytic activity. A biaryl urea group, prone to self-aggregation, was functionalized with a phosphinoalkyl thioether (P,S) hemilabile moiety and incorporated into a homoligated Pt(II) tweezer WLA complex. This urea-containing construct, which has been characterized by a single crystal X-ray diffraction study, can be switched in situ from a rigid fully closed state to a flexible semiopen state via Cl(-) induced changes in the coordination mode at the Pt(II) structural node. FT-IR and (1)H NMR spectroscopy studies were used to demonstrate that while extensive urea self-association persists in the flexible semiopen complex, these interactions are deterred in the rigid, fully closed complex because of geometric and steric restraints. Consequently, the urea moieties in the fully closed complex are able to catalyze a Diels-Alder reaction between cyclopentadiene and methyl vinyl ketone to generate 2-acetyl-5-norbornene. The free urea ligand and the semiopen complex show no such activity. The successful incorporation and regulation of a hydrogen bond donating catalyst in a WLA construct open the doors to a vast and rapidly growing catalogue of allosteric catalysts for applications in the detection and amplification of organic analytes.

  3. Investigation on the Coordinate Structures of the Rare Earth Metal Complexes with Edta and Cydta Ligands

    Institute of Scientific and Technical Information of China (English)

    WangJun; ZhangXiang-dong; ZhangYang; LiuZhen-rong

    2003-01-01

    The crystal and molecular structures of cydta(trans-1, 2-cyclohexanediaminetetraacetic acid) have been determined by single-crystal X-ray structure analyses. The reasons that REⅢ-edta and REⅢ-cydta complexes select different coordinate structures were discussed and illustrated through the comparison of the molecular and crystal structures between edta and cydta, (NH4)[Ⅲ(edta) (H2O)3]·5H2O and (NH4)[YⅢ(cydta)(H2O)2]·5H2O as well as (NH4)[GdⅢ(edta)(H2O)3]·5H2O and (NH4)[GdⅢ(cydta)(H2O)2]·5H2O complexes.

  4. Synthesis, characterization, and alkyne trimerization catalysis of a heteroleptic two-coordinate fe(i) complex.

    Science.gov (United States)

    Lipschutz, Michael I; Chantarojsiri, Teera; Dong, Yuyang; Tilley, T Don

    2015-05-20

    The synthesis of the first heteroleptic, two-coordinate Fe(I) complex IPr-Fe-N(SiMe3)DIPP (1) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; DIPP = 2,6-(i)Pr2-C6H3) is reported. Protonation of the Fe(II) bis(amido) complex Fe[N(SiMe3)DIPP]2 followed by addition of IPr and reduction by potassium graphite in a one-pot reaction results in good yields of 1. The redox activity of 1 and comparison between 1 and its reduction product by (57)Fe Mössbauer spectroscopy are discussed, and the reduction was found to be metal-based rather than ligand-based. The activity of 1 toward the catalytic cyclotrimerization of terminal and internal alkynes is described.

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

    Science.gov (United States)

    Peresypkina, Eugenia V.; Samsonenko, Denis G.; Vostrikova, Kira E.

    2015-04-01

    The results of the first steps in the design of coordination polymers based on penta- and heptacyanometallates of heavier d transitions metals are presented. The 2D structure of the coordination polymers: [{Mn(acacen)}2Ru(NO)(CN)5]n and two complexes composed of different cyanorhenates, [Ni(cyclam)]2[ReO(OH)(CN)4](ClO4)2(H2O)1.25 and [Cu(cyclam)]2[Re(CN)7](H2O)12, was confirmed by single crystal XRD study, the rhenium oxidation state having been proved by the magnetic measurements. An amorphism of [M(cyclam)]3[Re(CN)7]2 (M=Ni, Cu) polymers does not allow to define strictly their dimensionality and to model anisotropic magnetic behavior of the compounds. However, with high probability a honey-comb like layer structure could be expected for [M(cyclam)]3[Re(CN)7]2 complexes, studied in this work, because such an arrangement is the most common among the bimetallic assemblies of hexa- and octacyanometallates with a ratio [M(cyclam)]/[M(CN)n]=3/2. For the first time was prepared and fully characterized a precursor (n-Bu4N)2[Ru(NO)(CN)5], soluble in organic media.

  6. Core-Shell Coating Silicon Anode Interfaces with Coordination Complex for Stable Lithium-Ion Batteries.

    Science.gov (United States)

    Zhou, Jinqiu; Qian, Tao; Wang, Mengfan; Xu, Na; Zhang, Qi; Li, Qun; Yan, Chenglin

    2016-03-01

    In situ core-shell coating was used to improve the electrochemical performance of Si-based anodes with polypyrrole-Fe coordination complex. The vast functional groups in the organometallic coordination complex easily formed hydrogen bonds when in situ modifying commercial Si nanoparticles. The incorporation of polypyrrole-Fe resulted in the conformal conductive coating surrounding each Si nanoparticle, not only providing good electrical connection to the particles but also promoting the formation of a stable solid-electrolyte-interface layer on the Si electrode surface, enhancing the cycling properties. As an anode material for Li-ion batteries, modified silicon powders exhibited high reversible capacity (3567 mAh/g at 0.3 A/g), good rate property (549.12 mAh/g at 12 A/g), and excellent cycling performance (reversible capacity of 1500 mAh/g after 800 cycles at 1.2 A/g). The constructed novel concept of core-shell coating Si particles presented a promising route for facile and large-scale production of Si-based anodes for extremely durable Li-ion batteries, which provided a wide range of applications in the field of energy storage of the renewable energy derived from the solar energy, hydropower, tidal energy, and geothermal heat.

  7. Core-Shell Coating Silicon Anode Interfaces with Coordination Complex for Stable Lithium-Ion Batteries.

    Science.gov (United States)

    Zhou, Jinqiu; Qian, Tao; Wang, Mengfan; Xu, Na; Zhang, Qi; Li, Qun; Yan, Chenglin

    2016-03-01

    In situ core-shell coating was used to improve the electrochemical performance of Si-based anodes with polypyrrole-Fe coordination complex. The vast functional groups in the organometallic coordination complex easily formed hydrogen bonds when in situ modifying commercial Si nanoparticles. The incorporation of polypyrrole-Fe resulted in the conformal conductive coating surrounding each Si nanoparticle, not only providing good electrical connection to the particles but also promoting the formation of a stable solid-electrolyte-interface layer on the Si electrode surface, enhancing the cycling properties. As an anode material for Li-ion batteries, modified silicon powders exhibited high reversible capacity (3567 mAh/g at 0.3 A/g), good rate property (549.12 mAh/g at 12 A/g), and excellent cycling performance (reversible capacity of 1500 mAh/g after 800 cycles at 1.2 A/g). The constructed novel concept of core-shell coating Si particles presented a promising route for facile and large-scale production of Si-based anodes for extremely durable Li-ion batteries, which provided a wide range of applications in the field of energy storage of the renewable energy derived from the solar energy, hydropower, tidal energy, and geothermal heat. PMID:26863089

  8. Intramolecular substitutions of square planar rhodium(Ⅰ) catioriic complexes of ds-dicarbonyl nitrogen coordinated tridentate

    Institute of Scientific and Technical Information of China (English)

    袁国卿; 柳忠阳; 朱长城; 潘平来; 刘世宏

    1997-01-01

    Four kinds of square planar cis-dicarbonyl-N,N-bis(2-pyridylethyl)-p-substituted-phenylamino rhodium(Ⅰ) are reported.The changes of their structures were analyzed by XPS,IR and NMR spectroscopy The results show that the weak N→Rh coordinated bond can replace very soon the strong Rh-Cπ back donation bond to form tris-nitrogen coordinated complexes due to the steric effect when the temperature is over 50℃,This reaction is reversible.The bis-nitrogen coordinated structure of the complex recovered when put under the atmosphere of CO

  9. Meeting the needs of children with medical complexity using a telehealth advanced practice registered nurse care coordination model.

    Science.gov (United States)

    Cady, Rhonda G; Erickson, Mary; Lunos, Scott; Finkelstein, Stanley M; Looman, Wendy; Celebreeze, Margaret; Garwick, Ann

    2015-07-01

    Effective care coordination is a key quality and safety strategy for populations with chronic conditions, including children with medical complexity (CMC). However, gaps remain in parent report of the need for care coordination help and receipt of care coordination help. New models must close this gap while maintaining family-centered focus. A three-armed randomized controlled trial conducted in an established medical home utilized an advanced practice registered nurse intervention based on Presler's model of clinic-based care coordination. The model supported families of CMC across settings using telephone only or telephone and video telehealth care coordination. Effectiveness was evaluated from many perspectives and this paper reports on a subset of outcomes that includes family-centered care (FCC), need for care coordination help and adequacy of care coordination help received. FCC at baseline and end of study showed no significant difference between groups. Median FCC scores of 18.0-20.0 across all groups indicated high FCC within the medical home. No significant differences were found in the need for care coordination help within or between groups and over time. No significant difference was found in the adequacy of help received between groups at baseline. However, this indicator increased significantly over time for both intervention groups. These findings suggest that in an established medical home with high levels of FCC, families of CMC have unmet needs for care coordination help that are addressed by the APRN telehealth care coordination model.

  10. Coordination chemistry of a low-coordinate non-metal element: the case of electrophilic terminal phosphinidene complexes.

    Science.gov (United States)

    Villalba Franco, José Manuel; Schnakenburg, Gregor; Espinosa Ferao, Arturo; Streubel, Rainer

    2016-09-21

    3-Imino-azaphosphiridine complex 1 reacts with carbon monoxide to give 1,3-azaphosphetidinone complex 2, whereas with isocyanides 3a,b substitution occurred to yield complexes 4a,b. Oxidation of 1 using elemental sulfur afforded the first 1,3,2-thiazaphosphetidine-4-imine complex 5. DFT calculations provide insight into a manifold of pathways based on a common intermediate, a carbodiimide-to-phosphinidene complex, leading to P-N and P-C bond insertion products as well as ligand substitution products. PMID:27527532

  11. Integrated complex care coordination for children with medical complexity: A mixed-methods evaluation of tertiary care-community collaboration

    Directory of Open Access Journals (Sweden)

    Cohen Eyal

    2012-10-01

    Full Text Available Abstract Background Primary care medical homes may improve health outcomes for children with special healthcare needs (CSHCN, by improving care coordination. However, community-based primary care practices may be challenged to deliver comprehensive care coordination to complex subsets of CSHCN such as children with medical complexity (CMC. Linking a tertiary care center with the community may achieve cost effective and high quality care for CMC. The objective of this study was to evaluate the outcomes of community-based complex care clinics integrated with a tertiary care center. Methods A before- and after-intervention study design with mixed (quantitative/qualitative methods was utilized. Clinics at two community hospitals distant from tertiary care were staffed by local community pediatricians with the tertiary care center nurse practitioner and linked with primary care providers. Eighty-one children with underlying chronic conditions, fragility, requirement for high intensity care and/or technology assistance, and involvement of multiple providers participated. Main outcome measures included health care utilization and expenditures, parent reports of parent- and child-quality of life [QOL (SF-36®, CPCHILD©, PedsQL™], and family-centered care (MPOC-20®. Comparisons were made in equal (up to 1 year pre- and post-periods supplemented by qualitative perspectives of families and pediatricians. Results Total health care system costs decreased from median (IQR $244 (981 per patient per month (PPPM pre-enrolment to $131 (355 PPPM post-enrolment (p=.007, driven primarily by fewer inpatient days in the tertiary care center (p=.006. Parents reported decreased out of pocket expenses (p© domains [Health Standardization Section (p=.04; Comfort and Emotions (p=.03], while total CPCHILD© score decreased between baseline and 1 year (p=.003. Parents and providers reported the ability to receive care close to home as a key benefit. Conclusions Complex

  12. Assembly of Heterometallic Rigid-Rod Complexes and Coordination Oligomers from Gold(I) Metalloligands.

    Science.gov (United States)

    Cámara, Verónica; Barquero, Natalia; Bautista, Delia; Gil-Rubio, Juan; Vicente, José

    2015-07-01

    The reactions of TpylC6H4C≡CAuL (Tpyl = 2,2':6',2″-terpyridin-4'-yl; L = PPh3, CNXy; Xy = 2,6-dimethylphenyl) with MX2·nH2O (M = Fe, X = ClO4; M = Co, X = BF4; M = Zn, X = TfO, ClO4) in a 2:1 molar ratio give complexes [M(TpylC6H4C≡CAuL)2]X2. Similarly, the reactions of PPN[(TpylC6H4C≡C)2Au] (PPN = (Ph3P)2N) with an equimolar amount of MX2·nH2O give coordination oligomers [M{(TpylC6H4C≡C)2Au}]nXn (M = Fe, Zn, X = ClO4; M = Co, X = BF4). The complexes and oligomers have been isolated and characterized. The crystal structures of [Fe(TpylC6H4C≡CAuCNXy)2](ClO4)2 and [Co(TpylC6H4C≡CAuPPh3)2](BF4)2 have been determined by X-ray diffraction. The hydrodynamic sizes of complexes [M(TpylC6H4C≡CAuPPh3)2]X2 and coordination oligomers [M{(TpylC6H4C≡C)2Au}]nXn have been studied by NMR diffusion spectroscopy and dynamic light scattering measurements. PMID:26087239

  13. Syntheses and Characterization of Ruthenium(II) Tetrakis(pyridine)complexes: An Advanced Coordination Chemistry Experiment or Mini-Project

    Science.gov (United States)

    Coe, Benjamin J.

    2004-01-01

    An experiment for third-year undergraduate a student is designed which provides synthetic experience and qualitative interpretation of the spectroscopic properties of the ruthenium complexes. It involves the syntheses and characterization of several coordination complexes of ruthenium, the element found directly beneath iron in the middle of the…

  14. Coordination Complexes as Catalysts: The Oxidation of Anthracene by Hydrogen Peroxide in the Presence of VO(acac)[subscript 2

    Science.gov (United States)

    Charleton, Kimberly D. M.; Prokopchuk, Ernest M.

    2011-01-01

    A laboratory experiment aimed at students who are studying coordination chemistry of transition-metal complexes is described. A simple vanadyl acetylacetonate complex can be used as a catalyst in the hydrogen peroxide oxidation of anthracene to produce anthraquinone. The reaction can be performed under a variety of reaction conditions, ideally by…

  15. Low-Complexity Interference-Free Downlink Channel Assignment with Improved Performance in Coordinated Small Cells

    KAUST Repository

    Radaydeh, Redha M.

    2015-05-01

    This paper proposes a low-complexity interference-free channel assignment scheme with improved desired downlink performance in coordinated multi-antenna small-coverage access points (APs) that employ the open-access control strategy. The adopted system treats the case when each user can be granted an access to one of the available channels at a time. Moreover, each receive terminal can suppress a limited number of resolvable interfering sources via its highly-correlated receive array. On the other hand, the operation of the deployed APs can be coordinated to serve active users, and the availability of multiple physical channels and the use of uncorrelated transmit antennas at each AP are exploited to improve the performance of supported users. The analysis provides new approaches to use the transmit antenna array at each AP, the multiple physical channels, the receive antenna array at each user in order to identify interference-free channels per each user, and then to select a downlink channel that provides the best possible improved performance. The event of concurrent interference-free channel identification by different users is also treated to further improve the desired link associated with the scheduled user. The analysis considers the practical scenario of imperfect identification of interference-free channel by an active user and/or the imperfectness in scheduling concurrent users requests on the same channel. The developed formulations can be used to study any performance metric and they are applicable for any statistical and geometric channel models. © 2015 IEEE.

  16. Insights into copper coordination in the EcoRI-DNA complex by ESR spectroscopy

    Science.gov (United States)

    Ji, Ming; Tan, Likun; Jen-Jacobson, Linda; Saxena, Sunil

    2014-12-01

    The EcoRI restriction endonuclease requires one divalent metal ion in each of two symmetrical and identical catalytic sites to catalyse double-strand DNA cleavage. Recently, we showed that Cu2+ binds outside the catalytic sites to a pair of new sites at H114 in each sub-unit, and inhibits Mg2+-catalysed DNA cleavage. In order to provide more detailed structural information on this new metal ion binding site, we performed W-band (∼94 GHz) and X-band (∼9.5 GHz) electron spin resonance spectroscopic measurements on the EcoRI-DNA-(Cu2+)2 complex. Cu2+ binding results in two distinct components with different gzz and Azz values. X-band electron spin echo envelope modulation results indicate that both components arise from a Cu2+ coordinated to histidine. This observation is further confirmed by the hyperfine sub-level correlation results. W-band electron nuclear double resonance spectra provide evidence for equatorial coordination of water molecules to the Cu2+ ions.

  17. Divergent Coordination Chemistry: Parallel Synthesis of [2×2] Iron(II) Grid-Complex Tauto-Conformers.

    Science.gov (United States)

    Schäfer, Bernhard; Greisch, Jean-François; Faus, Isabelle; Bodenstein, Tilmann; Šalitroš, Ivan; Fuhr, Olaf; Fink, Karin; Schünemann, Volker; Kappes, Manfred M; Ruben, Mario

    2016-08-26

    The coordination of iron(II) ions by a homoditopic ligand L with two tridentate chelates leads to the tautomerism-driven emergence of complexity, with isomeric tetramers and trimers as the coordination products. The structures of the two dominant [Fe(II) 4 L4 ](8+) complexes were determined by X-ray diffraction, and the distinctness of the products was confirmed by ion-mobility mass spectrometry. Moreover, these two isomers display contrasting magnetic properties (Fe(II) spin crossover vs. a blocked Fe(II) high-spin state). These results demonstrate how the coordination of a metal ion to a ligand that can undergo tautomerization can increase, at a higher hierarchical level, complexity, here expressed by the formation of isomeric molecular assemblies with distinct physical properties. Such results are of importance for improving our understanding of the emergence of complexity in chemistry and biology.

  18. Rheb may complex with RASSF1A to coordinate Hippo and TOR signaling.

    Science.gov (United States)

    Nelson, Nicholas; Clark, Geoffrey J

    2016-06-01

    The TOR pathway is a vital component of cellular homeostasis that controls the synthesis of proteins, nucleic acids and lipids. Its core is the TOR kinase. Activation of the TOR pathway suppresses autophagy, which plays a vital but complex role in tumorigenesis. The TOR pathway is regulated by activation of the Ras-related protein Rheb, which can bind mTOR. The Hippo pathway is a major growth control module that regulates cell growth, differentiation and apoptosis. Its core consists of an MST/LATS kinase cascade that can be activated by the RASSF1A tumor suppressor. The TOR and Hippo pathways may be coordinately regulated to promote cellular homeostasis. However, the links between the pathways remain only partially understood. We now demonstrate that in addition to mTOR regulation, Rheb also impacts the Hippo pathway by forming a complex with RASSF1A. Using stable clones of two human lung tumor cell lines (NCI-H1792 and NCI-H1299) with shRNA-mediated silencing or ectopic overexpression of RASSF1A, we show that activated Rheb stimulates the Hippo pathway, but is suppressed in its ability to stimulate the TOR pathway. Moreover, by selectively labeling autophagic vacuoles we show that RASSF1A inhibits the ability of Rheb to suppress autophagy and enhance cell growth. Thus, we identify a new connection that impacts coordination of Hippo and TOR signaling. As RASSF1A expression is frequently lost in human tumors, the RASSF1A status of a tumor may impact not just its Hippo pathway status, but also its TOR pathway status.

  19. Rheb may complex with RASSF1A to coordinate Hippo and TOR signaling

    Science.gov (United States)

    Nelson, Nicholas; Clark, Geoffrey J.

    2016-01-01

    The TOR pathway is a vital component of cellular homeostasis that controls the synthesis of proteins, nucleic acids and lipids. Its core is the TOR kinase. Activation of the TOR pathway suppresses autophagy, which plays a vital but complex role in tumorigenesis. The TOR pathway is regulated by activation of the Ras-related protein Rheb, which can bind mTOR. The Hippo pathway is a major growth control module that regulates cell growth, differentiation and apoptosis. Its core consists of an MST/LATS kinase cascade that can be activated by the RASSF1A tumor suppressor. The TOR and Hippo pathways may be coordinately regulated to promote cellular homeostasis. However, the links between the pathways remain only partially understood. We now demonstrate that in addition to mTOR regulation, Rheb also impacts the Hippo pathway by forming a complex with RASSF1A. Using stable clones of two human lung tumor cell lines (NCI-H1792 and NCI-H1299) with shRNA-mediated silencing or ectopic overexpression of RASSF1A, we show that activated Rheb stimulates the Hippo pathway, but is suppressed in its ability to stimulate the TOR pathway. Moreover, by selectively labeling autophagic vacuoles we show that RASSF1A inhibits the ability of Rheb to suppress autophagy and enhance cell growth. Thus, we identify a new connection that impacts coordination of Hippo and TOR signaling. As RASSF1A expression is frequently lost in human tumors, the RASSF1A status of a tumor may impact not just its Hippo pathway status, but also its TOR pathway status. PMID:27034171

  20. New class of scorpionate: tris(tetrazolyl)-iron complex and its different coordination modes for alkali metal ions.

    Science.gov (United States)

    Park, Ka Hyun; Lee, Kang Mun; Go, Min Jeong; Choi, Sung Ho; Park, Hyoung-Ryun; Kim, Youngjo; Lee, Junseong

    2014-08-18

    We report formation of a new metallascorpionate ligand, [FeL3](3-) (IPtz), containing a Fe core and three 5-(2-hydroxyphenyl)-1H-tetrazole (LH2) ligands. It features two different binding sites, oxygen and nitrogen triangles, which consist of three oxygen or nitrogen donors from tetrazole. The binding affinities of the complex for three alkali metal ions were studied using UV spectrophotometry titrations. All three alkali metal ions show high affinities and binding constants (>3 × 10(6) M(-1)), based on the 1:1 binding isotherms to IPtz. The coordination modes of the alkali metals and IPtz in the solid were studied using X-ray crystallography; two different electron-donor sites show different coordination numbers for Li(+), Na(+), and K(+) ions. The oxygen triangles have the κ(2) coordination mode with Li(+) and κ(3) coordination mode with Na(+) and K(+) ions, whereas the nitrogen triangles show κ(3) coordination with K(+) only. The different binding affinities of IPtz in the solid were manipulated using multiple metal precursors. A Fe-K-Zn trimetallic complex was constructed by assembly of an IPtz ligand, K, and Zn precursors and characterized using X-ray crystallography. Oxygen donors are coordinated with the K ion via the κ(3) coordination mode, and nitrogen donors are coordinated with Zn metal by κ(3) coordination. The solid-state structure was confirmed to be a honeycomb coordination polymer with a one-dimensional infinite metallic array, i.e., -(K-K-Fe-Zn-Fe-K)n-.

  1. X-ray Emission Spectroscopy to Study Ligand Valence Orbitals in Mn Coordination Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Smolentsev, Grigory; Soldatov, Alexander V; Messinger, Johannes; Merz, Kathrin; Weyhermuller, Thomas; Bergmann, Uwe; Pushkar, Yulia; Yano, Junko; Yachandra, Vittal K.; Glatzel, Pieter

    2009-03-02

    We discuss a spectroscopic method to determine the character of chemical bonding and for the identification of metal ligands in coordination and bioinorganic chemistry. It is based on the analysis of satellite lines in X-ray emission spectra that arise from transitions between valence orbitals and the metal ion 1s level (valence-to-core XES). The spectra, in connection with calculations based on density functional theory (DFT), provide information that is complementary to other spectroscopic techniques, in particular X-ray absorption (XANES and EXAFS). The spectral shape is sensitive to protonation of ligands and allows ligands, which differ only slightly in atomic number (e.g., C, N, O...), to be distinguished. A theoretical discussion of the main spectral features is presented in terms of molecular orbitals for a series of Mn model systems: [Mn(H2O)6]2+, [Mn(H2O)5OH]+, [Mn(H2O)5NH2]+, and [Mn(H2O)5NH3]2+. An application of the method, with comparison between theory and experiment, is presented for the solvated Mn2+ ion in water and three Mn coordination complexes, namely [LMn(acac)N3]BPh4, [LMn(B2O3Ph2)(ClO4)], and [LMn(acac)N]BPh4, where L represents 1,4,7-trimethyl-1,4,7-triazacyclononane, acac stands for the 2,4-pentanedionate anion, and B2O3Ph2 represents the 1,3-diphenyl-1,3-dibora-2-oxapropane-1,3-diolato dianion.

  2. Synthesis and structural evaluation of five coordination complexes of benzenepentacarboxylic acid with aza-donor ligands

    Science.gov (United States)

    Shimpi, Manishkumar R.; Biswas, Sharmita Nandy; Sarkar, Sohini; Pedireddi, V. R.

    2016-06-01

    Synthesis and structural features of five new coordination assemblies, [Co(bpyH)(H2O)5](BPCH)·(bpyH2)0.5·(H2O) (1a), [{Cu(H2O)3}·{Cu0.5(bpy)0.5(H2O)0.5}2(μ-BPCH)] (1b), [{Cd0.5(BPCH)}2·{Cd0.5(bpy)(H2O)2}2]·6(H2O) (1c), [Cu(BPCH2)(bpyeaH)]·2(H2O) (1d) and [Cd2 (bpyea)0.5(oxalate)0.5(μ-BPC) (H2O)]·(bpyeaH2)·2(H2O) (1e), have been reported. All the assemblies were prepared by co-crystallization of benzenepentacarboxylic acid (BPCH5) either with 4,4‧-bipyridine (bpy) or 1,2-bis(4-pyridyl)ethane (bpyea) in the presence of a transition metal ion (either Co(II), Cu(II) or Cd(II)) as the case may be. All the five compounds were synthesized by hydrothermal method and structures were determined by single crystal X-ray diffraction. All the obtained compounds, 1a-1e, exhibit distinct 3-D polymeric architectures either in the form of stacked layers or host-guest networks in which water molecules play a pivotal role providing additional stabilization by coordinate bonds as well as hydrogen bonds. Other non-covalent interactions such as C-H … π and π … π stacking also participate in the formation of exotic 3-D structures of these complexes.

  3. Eddy-correlation measurements of benthic fluxes under complex flow conditions: Effects of coordinate transformations and averaging time scales

    DEFF Research Database (Denmark)

    Lorke, Andreas; McGinnis, Daniel F.; Maeck, Andreas

    2013-01-01

    hours of continuous eddy-correlation measurements of sediment oxygen fluxes in an impounded river, we demonstrate that rotation of measured current velocities into streamline coordinates can be a crucial and necessary step in data processing under complex flow conditions in non-flat environments...... with complex topography. We found that under these conditions neither time series detrending nor coordinate rotation can remove low-frequency velocity variations completely. These variations result in spurious flux contributions and in a pronounced dependence of the derived fluxes on averaging time scales......Eddy-correlation measurements of sediment oxygen uptake rates in aquatic systems are increasingly used to obtain areal-averaged fluxes with a high temporal resolution. Here we discuss the effects of coordinate rotation and averaging time scale for Reynolds decomposition on flux estimates. Using 119...

  4. Characterization of Ce SUP 3+-tributyl phosphate coordination complexes produced by fused droplet electrospray ionization with a target capillary

    Energy Technology Data Exchange (ETDEWEB)

    Gary S. Groenewold; Jean-Jacques Gaumet

    2011-12-01

    Coordination complexes containing Ce(III) and tri-n-butyl phosphate (TBP) in the 1+, 2+ and 3+ charge states were generated using desorption electrospray ionization (DESI) mass spectrometry, in which the analyte solutions were supplied via a target capillary orthogonally situated with respect to the electrospray. Comparison with direct electrospray (ESI) showed that the same coordination complexes were produced in each experiment, and could be described by the general formula [Ce(NO3)m=0-2(TBP)n](3-m)+. This result indicates that DESI has utility for measuring metal speciation for metal ligand solutions where the gas-phase complexes generated by ESI have been correlated with solution speciation. Such an application would be useful for analyses where it is desirable to limit the total amount of metal being handled, or that have solvent systems that are not readily amenable to ESI. Both the direct ESI and DESI mass spectra showed similar trends with respect to the TBP:Ce ratio, viz. high values tend to favor formation of a larger fraction of the 1+ species, and the 2+ and 3+ species become relatively more important as the ratio is decreased. Within individual charge state ion envelopes, lower TBP:Ce ratios produce coordination complexes with fewer ligands, a trend also seen using both approaches. These trends again point toward strong similarity between the direct ESI and DESI analyses of the metal-ligand solutions. The DESI experiments were less sensitive for measuring the coordination complexes compared to the direct ESI experiments, by a factor of 10 - 100 depending on whether minimum detectable concentration or absolute ion abundances were considered. Nevertheless, mid-picomolar quantities of coordination complexes were measured using the target capillary, indicating that sensitivity would be sufficient for measuring species in many industrial separations processes.

  5. Polyoxometalate coordinated transition metal complexes as catalysts: Oxidation of styrene to benzaldehyde/benzoic acid

    Indian Academy of Sciences (India)

    Srinivasa Rao Amanchi; Anjali Patel; Samar K Das

    2014-11-01

    Oxidation of styrene is carried out by using heptamolybdate coordinated transition metal (Co2+, Zn2+) complexes, [2-ampH]4[{Co(H2O)5}Mo7O24]·9H2O (1), [3-ampH]4[{Co(H2O)5}Mo7O24]·9H2O (2), [2-ampH]4[{Zn(H2O)5}Mo7O24]·4H2O (3) and [3-ampH]4[{Zn(3-ampy)(H2O)4}Mo7O24]·4H2O (4) as catalysts and H2O2 as an oxidant at 80°C. The leaching study has been carried out to check the quality of catalyst and it has been reused for three times with good percentage of conversion. For the first two catalysts (compounds 1 and 2), the major product obtained is benzaldehyde, and benzoic acid is the major product for next two catalysts (compounds 3 and 4). Stability of the catalysts has been analyzed by IR, UV-spectroscopy and powder X-ray crystallography.

  6. Electronic Transitions as a Probe of Tetrahedral versus Octahedral Coordination in Nickel(II) Complexes: An Undergraduate Inorganic Chemistry Experiment.

    Science.gov (United States)

    Filgueiras, Carlos A. L.; Carazza, Fernando

    1980-01-01

    Discusses procedures, theoretical considerations, and results of an experiment involving the preparation of a tetrahedral nickel(II) complex and its transformation into an octahedral species. Suggests that fundamental aspects of coordination chemistry can be demonstrated by simple experiments performed in introductory level courses. (Author/JN)

  7. Identification of Copper(II) Complexes in Aqueous Solution by Electron Spin Resonance: An Undergraduate Coordination Chemistry Experiment.

    Science.gov (United States)

    Micera, G.; And Others

    1984-01-01

    Background, procedures, and results are provided for an experiment which examines, through electron spin resonance spectroscopy, complex species formed by cupric and 2,6-dihydroxybenzoate ions in aqueous solutions. The experiment is illustrative of several aspects of inorganic and coordination chemistry, including the identification of species…

  8. Coordination and conformational isomers in mononuclear iron complexes with pertinence to the [FeFe] hydrogenase active site.

    Science.gov (United States)

    Orthaber, Andreas; Karnahl, Michael; Tschierlei, Stefanie; Streich, Daniel; Stein, Matthias; Ott, Sascha

    2014-03-21

    A series of six mononuclear iron complexes of the type [Fe(X-bdt)(P(R)2N(Ph)2)(CO)] (P(R)2N(Ph)2 = 1,5-diaza-3,7-diphosphaoctane, bdt = benzenedithiolate with X = H, Cl2 or Me and R = Ph, Bn, Cyc or tert-Bu) was prepared. This new class of penta-coordinate iron complexes contains a free coordination site and a pendant base as essential structural features of the [FeFe]-hydrogenase active site. The bidentate nature of the P(R)2N(Ph)2 ligands was found to be crucial for the preferential formation of coordinatively unsaturated penta-coordinate complexes, which is supported by first principle calculations. IR-spectroscopic data suggest the presence of coordination isomers around the metal center, as well as multiple possible conformers of the P(R)2N(Ph)2 ligand. This finding is further corroborated by X-ray crystallographic and computational studies. (31)P{(1)H}-NMR- and IR-spectroscopic as well as electrochemical measurements show that the electronic properties of the complexes are strongly, and independently, influenced by the P-substituents at the P(R)2N(Ph)2 ligand as well as by modifications of the bdt bridge. These results illustrate the advantages of this modular platform, which allows independent and selective tuning through site specific modifications. Potential catalytic intermediates, namely singly reduced and protonated complexes, have been further investigated by spectroscopic methods and exhibit remarkable stability. Finally, their general capacity for electro-catalytic reduction of protons to molecular hydrogen was verified.

  9. Stability and Reactivity of Cyclometallated Naphthylamine Complexes in Pd-C Bond Insertion Reactions with Coordinated Alkynylphosphanes

    KAUST Repository

    Chen, Shuli

    2013-09-17

    Phenylbis(phenylethynyl)phosphane PhP(C≡CPh)2 coordinates regiospecifically to the α-methyl-chiral ortho-platinated and -palladated naphthylamine units at the positions trans to the nitrogen donors. The P→Pt coordination bond is kinetically inert, whereas the P→Pd bond is labile. Upon heating of these phosphane complexes at 70 °C, one of the C≡C bonds in the coordinated PhP(C≡CPh)2 was activated towards an intermolecular Pd-C bond insertion reaction with an external ortho-palladated naphthylamine ring. No intramolecular insertion reaction occurred. In contrast to its palladium analogue, the ortho-platinated ring is not reactive towards coordinated PhP(C≡CPh)2, although it can promote the Pd-C bond insertion reaction. However, despite the high kinetic stability of the P→Pt coordination, the organoplatinum unit is a noticeably weaker activator than its organopalladium counterpart. The chirality of the reacting ortho-metallated naphthylamine ligand exhibited high stereochemical influence on the formation of the new stereogenic phosphorus center during the course of these C-C bond-formation reactions. The coordination chemistry and the absolute stereochemistry of the dimetallic products were determined by single-crystal X-ray crystallographic analysis. The asymmetric monoinsertion of PhP(C≡CPh)2 coordinated to a cyclometallated N,N-dimethyl naphthyl/benzylamine template into the Pd-C bonds of N,N-dimethylnaphthylamine palladacycles has been demonstrated for the synthesis of a variety of new P-stereogenic homo- or heterodimetallic complexes. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Two Zn(II) coordination complexes assembled by trithiocyanuric acid and two different N-donor auxiliary ligands.

    Science.gov (United States)

    He, Xiao Xiao; Guo, Ya Mei

    2014-08-01

    The dipyridyl-type building blocks 4-amino-3,5-bis(pyridin-3-yl)-1,2,4-triazole (3-bpt) and 4,4'-bipyridine (bpy) have been used to assemble with Zn(II) in the presence of trithiocyanuric acid (ttcH3) to afford two coordination compounds, namely bis[4-amino-3,5-bis(pyridin-3-yl)-1,2,4-triazole-κN(3)]bis(trithiocyanurato-κ(2)N,S)zinc(II), [Zn(C3H2N3S3)2(C12H10N6)2]·2H2O, (1), and catena-poly[[[bis(trithiocyanurato-κ(2)N,S)zinc(II)]-μ-4,4'-bipyridine-κ(2)N:N'] 4,4'-bipyridine monosolvate], {[Zn2(C3H2N3S3)4(C10H8N2)3]·C10H8N2}n, (2). Single-crystal X-ray analysis indicates that complex (1) is a mononuclear structure, while complex (2) presents a one-dimensional chain coordination motif. In both complexes, the central Zn(II) cation adopts an octahedral geometry, coordinated by four N- and two S-donor atoms. Notably, trithiocyanurate (ttcH2(-)) adopts the same bidentate chelating coordination mode in each complex and exists in the thione tautomeric form. The 3-bpt co-ligand in (1) adopts a monodentate coordination mode and serves as a terminal pendant ligand, whereas the 4,4'-bipyridine (bpy) ligand in (2) adopts a bidentate-bridging coordination mode. The different coordination characters of the different N-donor auxiliary ligands lead to structural diversity for complexes (1) and (2). Further analysis indicates that the resultant three-dimensional supramolecular networks for (1) and (2) arise through intermolecular N-H...S and N-H...N hydrogen bonds. Both complexes have been further characterized by FT-IR spectroscopy and elemental analyses.

  11. A Series of Transition-metal Coordination Complexes Assembled from 3-Nitrophthalic Acid and Thiabendazole: Synthesis, Structure and Properties

    International Nuclear Information System (INIS)

    In order to explore new coordination frameworks with novel designed 3-nitrophthalic acid and the same N-donor ancillary ligand, a series of novel coordination complexes, namely, [Cd2(3-NPA)2(TBZ)2(H2O)2]·2H2O (1), [Zn2(3-NPA)2(TBZ)2] (2), [Zn2O(3-NPA)(TBZ)(H2O)]n (3), [Co(3-NPA)(TBZ)(H2O)]n (4) (3-NPAH2 = 3-nitrophthalic acid), have been hydrothermally synthesized through the reaction of 3-nitrophthalic acid with divalent transition-metal salts in the presence of N-donor ancillary coligand (TBZ = thiabendazole). As a result of various coordination modes of the versatile 3-NPAH2 and the coligand TBZ, these complexes exhibit structural diversity. X-ray structure analysis reveals that 1 and 2 are 0D molecular rings, while 3 and 4 are one-dimensional (1D) infinite chain polymers. And the weak O-H···O hydrogen bonds and C-H···O nonclassical hydrogen bonds as well as π-π stacking also play important roles in affecting the final structure where complexes 1, 3 and 4 have 3D supramolecular architectures, while complex 2 has a 2D supramolecular network. Also, IR spectra, fluorescence properties and thermal decomposition process of complexes 1-4 were investigated

  12. Divalent and trivalent gas-phase coordination complexes of californium: evaluating the stability of Cf(ii).

    Science.gov (United States)

    Dau, Phuong D; Shuh, David K; Sturzbecher-Hoehne, Manuel; Abergel, Rebecca J; Gibson, John K

    2016-08-01

    The divalent oxidation state is increasingly stable relative to the trivalent state for the later actinide elements, with californium the first actinide to exhibit divalent chemistry under moderate conditions. Although there is evidence for divalent Cf in solution and solid compounds, there are no reports of discrete complexes in which Cf(II) is coordinated by anionic ligands. Described here is the divalent Cf methanesulfinate coordination complex, Cf(II)(CH3SO2)3(-), prepared in the gas phase by reductive elimination of CH3SO2 from Cf(III)(CH3SO2)4(-). Comparison with synthesis of the corresponding Sm and Cm complexes reveals reduction of Cf(III) and Sm(III), and no evidence for reduction of Cm(III). This reflects the comparative 3+/2+ reduction potentials: Cf(3+) (-1.60 V) ≈ Sm(3+) (-1.55 V) ≫ Cm(3+) (-3.7 V). Association of O2 to the divalent complexes is attributed to formation of superoxides, with recovery of the trivalent oxidation state. The new gas-phase chemistry of californium, now the heaviest element to have been studied in this manner, provides evidence for Cf(II) coordination complexes and similar chemistry of Cf and Sm. PMID:27424652

  13. Synthesis, crystal structure and spectroscopic properties of a supramolecular zinc(II) complex with N2O2 coordination sphere.

    Science.gov (United States)

    Dong, Wen-Kui; Zhang, Li-Sha; Sun, Yin-Xia; Zhao, Meng-Meng; Li, Gang; Dong, Xiu-Yan

    2014-01-01

    A new hexa-coordinated zinc(II) complex, namely [ZnL(H2O)2]n, with N2O2 coordination sphere (H2L=4,4'-dibromo-6,6'-dichloro-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol) has been synthesized and structurally characterized by elemental analyses, IR, UV-vis spectra and TG-DTA analyses, etc. Crystallographic data are monoclinic, space group P2(1)/c, a=24.634(2)Å, b=10.144(1)Å, c=7.9351(6)Å, β=91.371(2)°, V=1982.4(3)Å(3), Dc=2.099 g/cm(3), Z=4. The zinc(II) complex exhibits a slightly distorted octahedral geometry with halogen-substituted Salen-type bisoxime forming the basal N2O2 coordination sphere and two oxygen atoms from two coordinated water molecules in the axial position. The hydrogen-bonding and π-π stacking interactions have stabilized the zinc(II) complex molecules to form a self-assembling infinite dual metal-water chain-like structure with the nearest Zn⋯Zn distance of 4.954(4)Å.

  14. Trinuclear nickel coordination complexes of phenanthrene-9,10-dione dioxime.

    Science.gov (United States)

    Williams, Owen M; Cowley, Alan H

    2016-04-01

    A trinuclear nickel complex of phenanthrene-9,10-dione dioxime (H2pqd), namely bis-[μ2-9,10-bis-(oxido-imino)-phenanthrene]-bis-[μ2-10-(oxido-imino)phenanthrene-9-one oxime](phenanthrene-9,10-dione dioxime)trinickel(II) toluene disolvate, [Ni3(C14H8N2O2)2(C14H9N2O2)2(C14H10N2O2)]·2C7H8, has been isolated and its crystal structure determined. This complex features three independent Ni(II) atoms that are arranged in a triangular fashion along with five supporting ligands. There are two square-planar Ni(II) atoms and a third pseudo-octa-hedral Ni(II) atom. While the square-planar Ni(II) atoms are stacked, there are no ligand bridges between them. Each square-planar Ni(II) atom, however, bridges with the pseudo-octa--hedral Ni(II) atom through Ni-N-O-Ni and Ni-O-Ni bonds. A fluorido-bor-ation reaction of the proton-bridged species gave the analogous complex bis-(μ2-bis-{[10-(oxido-imino)-9,10-di-hydro-phenanthren-9-yl-idene]amino}di-fluorido-borato)(phenanthrene-9,10-dione dioxime)trinickel(II) dichloromethane trisolvate, [Ni3(C28H16BF2N4O2)4(C14H10N2O2)]·3CH2Cl2, which shows the same binding structure, but features a widened Ni-Ni inter-action between the square-planar Ni(II) atoms. The proton-bridged complex completes the macrocyclic coordination around the square-planar Ni(II) atoms by means of an O-H⋯O hydrogen bond. Both compounds feature O-H⋯N hydrogen bonds between the oxime and the N atoms attached to square-planar nickel atom. The nickel units show no direct inter-action with their nearest neighbors in the extended lattice. Two π-stacking inter-actions between adjacent mol-ecules are found: one with a centroid-centroid distance of 3.886 (2) Å and the other with a centroid-centroid distance of 4.256 (3) Å. In the latter case, although not aromatic, the distance to the centroid of the central phenanthrene ring is shorter, with a distance of 3.528 (3) Å. Toluene mol-ecules occupy the solvent channels that are oriented along the c axis. In

  15. Role of Occupational Therapy in Case Management and Care Coordination for Clients With Complex Conditions.

    Science.gov (United States)

    Robinson, Monica; Fisher, Thomas F; Broussard, Kim

    2016-01-01

    Specific aspects of the profession of occupational therapy support a distinct value for its practitioners participating fully in the development of case management and care coordination systems. The expectation in the 21st century is that the U.S. health care system must be transformed from one that promotes volume of service to one that promotes value of care. Case management and care coordination will be critical components of that transformation. Occupational therapy's principles, education, practice, approach, and perspective offer much to benefit this increased attention to case management and care coordination. Occupational therapy practitioners should promote themselves and their profession as these system changes develop.

  16. Bis(2-acetylpyridine-κ2N,Osilver(I tetrafluoridoborate: a complex with silver in a seesaw coordination geometry

    Directory of Open Access Journals (Sweden)

    Michael A. O'Donnell

    2010-12-01

    Full Text Available The reaction of 2-acetylpyridine with silver(I tetrafluoridoborate leads to the discrete title complex, [Ag(C7H7NO2]BF4, in the cation of which the Ag atom is coordinated by two 2-acetylpyridine ligands, each of which is N,O-bidentate, albeit with stronger bonding to the N atoms [Ag—N = 2.2018 (15 and 2.2088 (14 Å; Ag—O = 2.5380 (13 and 2.5454 (13 Å]. The four-coordinate Ag atom has a seesaw coordination geometry with a τ4 index of 0.51. The tetrafluoridoborate anion is disordered over two orientations with 0.568 (10:0.432 (10 occupancies.

  17. Solubilization of silica: Synthesis, characterization and study of penta-coordinated pyridine N-oxide silicon complexes

    Indian Academy of Sciences (India)

    Subramania Ranganathan; Ch Chandrashekhar Rao; Suvarchala Devi Vudayagiri; Y B R D Rajesh; B Jagadeesh

    2004-03-01

    In an effort to design agents that could solubilize silica in water, under ambient conditions and pH, as takes place in nature, novel zwitterionic, penta-oxo-coordinated silicon compounds with siliconate cores have been prepared from 4-substituted pyridine N-oxides (H, OMe, morpholino, NO2) as donor ligands, their structures established by 1H, 13C and MS, and the coordination number of silicon, by 29Si NMR. The formation of complexes from pyridine N-oxides is noteworthy since they arise from interaction with a weakly nucleophilic oxygen centre. The ability of the pyridine N-oxides to enhance the solubilization of silica in water has been experimentally demonstrated. Possible rationalization of this observation on the basis of O→Si coordination via the oxygen atom of pyridine N-oxide is suggested.

  18. Superchiral Pd3 L6 Coordination Complex and Its Reversible Structural Conversion into Pd3 L3 Cl6 Metallocycles.

    Science.gov (United States)

    Jurček, Ondřej; Bonakdarzadeh, Pia; Kalenius, Elina; Linnanto, Juha Matti; Groessl, Michael; Knochenmuss, Richard; Ihalainen, Janne A; Rissanen, Kari

    2015-12-14

    Large, non-symmetrical, inherently chiral bispyridyl ligand L derived from natural ursodeoxycholic bile acid was used for square-planar coordination of tetravalent Pd(II) , yielding the cationic single enantiomer of superchiral coordination complex 1 Pd3 L6 containing 60 well-defined chiral centers in its flower-like structure. Complex 1 can readily be transformed by addition of chloride into a smaller enantiomerically pure cyclic trimer 2 Pd3 L3 Cl6 containing 30 chiral centers. This transformation is reversible and can be restored by the addition of silver cations. Furthermore, a mixture of two constitutional isomers of trimer, 2 and 2', and dimer, 3 and 3', can be obtained directly from L by its coordination to trans- or cis-N-pyridyl-coordinating Pd(II) . These intriguing, water-resistant, stable supramolecular assemblies have been thoroughly described by (1) H DOSY NMR, mass spectrometry, circular dichroism, molecular modelling, and drift tube ion-mobility mass spectrometry.

  19. Molecular orbital study of coordinated dioxygen. I. Structure and bonding of model monomeric Co(II) complexes

    Science.gov (United States)

    Boča, R.

    1980-08-01

    The CNDO—UHF type of MO—LCAO—SCP calculation is carried out for model systems of dioxygen fixation: O 2 CoCl 4L 2- complexes in which L = none and L = NH 3. A geometry variation is performed with respect to 5 internal coordinates describing the degrees of freedom of the Co—O 2 group. The calculated geometry, spin densities and atomic charges agree with available data based on X-ray and ESR measurements of real dioxygen carriers. Structure and bonding of complexes are discussed in more detail.

  20. Analysis of Heme Iron Coordination in DGCR8: The Heme-Binding Component of the Microprocessor Complex.

    Science.gov (United States)

    Girvan, Hazel M; Bradley, Justin M; Cheesman, Myles R; Kincaid, James R; Liu, Yilin; Czarnecki, Kazimierz; Fisher, Karl; Leys, David; Rigby, Stephen E J; Munro, Andrew W

    2016-09-13

    DGCR8 is the RNA-binding partner of the nuclease Drosha. Their complex (the "Microprocessor") is essential for processing of long, primary microRNAs (pri-miRNAs) in the nucleus. Binding of heme to DGCR8 is essential for pri-miRNA processing. On the basis of the split Soret ultraviolet-visible (UV-vis) spectrum of ferric DGCR8, bis-thiolate sulfur (cysteinate, Cys(-)) heme iron coordination of DGCR8 heme iron was proposed. We have characterized DGCR8 heme ligation using the Δ276 DGCR8 variant and combined electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), electron nuclear double resonance, resonance Raman, and electronic absorption spectroscopy. These studies indicate DGCR8 bis-Cys heme iron ligation, with conversion from bis-thiolate (Cys(-)/Cys(-)) axial coordination in ferric DGCR8 to bis-thiol (CysH/CysH) coordination in ferrous DGCR8. Pri-miRNA binding does not perturb ferric DGCR8's optical spectrum, consistent with the axial ligand environment being separated from the substrate-binding site. UV-vis absorption spectra of the Fe(II) and Fe(II)-CO forms indicate discrete species exhibiting peaks with absorption coefficients substantially larger than those for ferric DGCR8 and that previously reported for a ferrous form of DGCR8. Electron-nuclear double resonance spectroscopy data exclude histidine or water as axial ligands for ferric DGCR8 and favor bis-thiolate coordination in this form. UV-vis MCD and near-infrared MCD provide data consistent with this conclusion. UV-vis MCD data for ferrous DGCR8 reveal features consistent with bis-thiol heme iron coordination, and resonance Raman data for the ferrous-CO form are consistent with a thiol ligand trans to the CO. These studies support retention of DGCR8 cysteine coordination upon reduction, a conclusion distinct from those of previous studies of a different ferrous DGCR8 isoform.

  1. Coordination chemistry of gadolinium complexes having pyridine carboxylate units in relation with the medical imagery; Chimie de coordination de complexes de gadolinium a motifs pyridine carboxylate en relation avec l'imagerie medicale

    Energy Technology Data Exchange (ETDEWEB)

    Gateau, C.; Chatterton, N.; Nonat, A.; Mazzanti, M. [CEA Grenoble, Dept. de Recherche Fondamentale sur la Matiere Condensee (DRFMC/SCIB/LAI) Lab. de Reconnaissance Ionique, 38 (France); Pecaut, J. [CEA Grenoble, Dept. de Recherche Fondamentale sur la Matiere Condensee (DRFMC/SCIB/LAI) Lab. de Coordination et Chiralite, 38 (France); Borel, A.; Merbach, A.; Heim, L. [Lausanne Univ., Institut de Chimie Minerale et Analytique (Switzerland)

    2005-07-01

    In order to study the influence of the coordination sphere on the properties which govern the relaxivity, ligands containing pyridine carboxylates units have been particularly studied. It has been shown that the tripodal ligand tpaa forms with gadolinium (III) a neutral complex having a relaxivity (r1p=13.3 mM{sup -1} at 298 K and 60 MHz) which is three times superior to the contrast agents currently used in NMR Imaging. To explain this remarkably relaxivity, two new ligands analogous to the tpaa: the tpatcn and the bpeda containing pyridine carboxylate units bound to one or several aliphatic nitrogen have been studied in modulating the number of coordination sites and the symmetry degree. The study of the relaxivity of the corresponding gadolinium (III) complexes gives precious data on the understanding of the results in the case of the complex [Gd(tpaa)]. The synthesis and the properties of these gadolinium (III) complexes will be presented during this conference. (O.M.)

  2. Direct measurement and modulation of single-molecule coordinative bonding forces in a transition metal complex

    DEFF Research Database (Denmark)

    Hao, Xian; Zhu, Nan; Gschneidtner, Tina;

    2013-01-01

    substrate surfaces and gold-coated atomic force microscopy tips. The coordination and bond breaking between terpyridine and osmium are followed in situ by electrochemically controlled atomic force microscopy at the single-molecule level. The redox state of the central metal atom is found to have...

  3. Selenate adsorption on pre-coordinated Fe3+-silane complexes grafted on mesoporous silicas.

    Science.gov (United States)

    Otsuka, Ryo; Yoshitake, Hideaki

    2014-08-01

    Fe3+ was coordinated N-[2-(aminoethyl)-3-aminopropyltriethoxysilane], AEAPTES, followed by being grafted on MCM-41, SBA-15 and Cab-O-sil M7D. The mixing ratio, n = [AEAPTES]/[Fe], in the above coordination reaction was varied from 1 to 3. These nine functionalized silicas, denoted as Fe(en)n-silica (n = 1, 2, 3 and silica = MCM-41, SBA-15 and M7D), were used for the adsorption of aqueous selenate. The saturation of adsorption isotherm occurred at Se/Fe = 2 on Fe(en)2- MCM-41 and Fe(en)2-SBA-15, while Fe(en)- and Fe(en)3-MCM-41 and Fe(en)- and Fe(en)3-SBA-15 adsorbed selenate until Se/Fe = 1. The saturation at Se/Fe = 1 was obtained for all absorbents prepared with M7D substrate, suggesting a transformation of the adsorption sites realized on Fe(en)2-MCM-41 and Fe(en)2-SBA-15. The concave curvature of the surface of mesoporous silicas is possibly critical to retain the coordination structure of adsorption sites. The largest capacity obtained among these adsorbents was 1.1 mmol/g, found on Fe(en)2-SBA-15. The structure of adsorption sites was analysed by X-ray absorption spectroscopies in order to obtain the evidences for the distortion of coordination structure induced by grafting and the bond formation between Se and Fe after adsorption. PMID:25936127

  4. Synthesis, spectroscopy, thermal studies and supramolecular structures of two new alkali-earth 4-nitrobenzoate complexes containing coordinated imidazole

    Indian Academy of Sciences (India)

    Bikshandarkoil R Srinivasan; Jyoti V Sawant; Pallepogu Raghavaiah

    2007-01-01

    The reaction of hydrated magnesium or calcium 4-nitrobenzoate (4-nba) generated in situ, with imidazole (Im) results in the formation of the complexes [Mg(H2O)2(Im)2(4-nba)2] 1 and [Ca(H2O)3(Im)(4-nba)2]$\\cdot$Im 2, which exhibit the same metal:4-nba:Im ratio but different degrees of hydration. Complex 1 crystallizes in the triclinic $_{\\bar{i}}$ space group and the Mg atom is located on an inversion centre, while 2 crystallizes in the monoclinic 21/ space group and all atoms are located in general positions. In 1 the Im ligands, which are trans to each other, are coordinated to Mg, while 2 contains coordinated as well as free Im. The monodentate 4-nba ligands are disposed trans to each other in 1, while they adopt a cis orientation in 2 resulting in different supramolecular structures. Complex 1 exhibits two types of H-bonding interactions namely O-HO and N-HO, while in 2 three varieties of H-bond, viz. O-HO, N-HO and O-HN are observed. The Im ligand functions as a bifurcated H-bond donor in 1 while the O atom of the nitro group functions as a H-bond acceptor. In contrast, the nitro group in 2 is not involved in any H-bonding interactions. The free Im in 2 functions as a bifurcated acceptor and forms an extended chain linking adjacent complex molecules. The chains thus formed are further cross-linked with the aid of H-donor bonds from both the free as well as the coordinated Im. Both 1 and 2 exhibit - stacking interactions. Complex 1 is thermally more stable as compared to 2, and both complexes can be dehydrated to the corresponding anhydrous complexes by heating at 140 and 100°C respectively. At elevated temperatures, both the complexes can be pyrolysed to the corresponding oxide. The anhydrous complexes can be rehydrated to obtain the starting hydrated materials.

  5. Synthesis, structural, thermal and optical studies of rare earth coordinated complex: Tb(Sal){sub 3}Phen

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Gagandeep; Dwivedi, Y. [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Rai, S.B., E-mail: sbrai49@yahoo.co.in [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, Varanasi 221005 (India)

    2011-11-01

    Highlights: {yields} RE coordinated complex of Tb(Sal){sub 3}Phen in crystalline phases were synthesized. {yields} Enhancement in luminescence of Tb{sup 3+} was observed in complex on 355 nm excitation. {yields} Fluorescence enhancement is due to the efficient energy transfer from Sal to Tb{sup 3+}. {yields} An observed increase in lifetime of Tb{sup 3+} is due to encapsulation in Sal/Phen network. {yields} The present system is a deserving candidate for LSC when coupled with solar cells. - Abstract: Complexes of salicylic acid (Sal) and 1,10-phenanthroline (Phen) were synthesized coordinated with terbium ion (Tb{sup 3+}) in crystalline phases. The structural characterizations of the lanthanide complex were made using FT-IR, NMR ({sup 1}H and {sup 13}C) and XRD techniques. These measurements confirm the formation of Tb(Sal){sub 3}Phen complex structure. The thermal aspects of the complex were examined using DTA and TGA techniques. An enhancement in luminescence intensity of Tb{sup 3+} ion bands were observed in Tb(Sal){sub 3}Phen complex as compared to TbCl{sub 3} crystals on 355 nm laser excitation. Enhancement is reported due to the efficient energy transfer process from Sal to Tb{sup 3+} ions. This is also confirmed by the time resolved photoluminescence spectroscopy with increase in lifetime of Tb{sup 3+} ions due to encapsulation in Sal/Phen network. Our system in itself can be a deserving candidate for luminescent solar collector material when coupled with solar cells.

  6. Anion coordination complex [ClPt(bpt)4]Cl (bpt= N,N’-bis(3-pyridylmethyl)-2-thiourea)

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The anion coordination complex,[ClPt(bpt)4]Cl (bpt=N,N’-bis(3-pyridylmethyl)-2-thiourea),was synthesized and studied by X-ray crystal structure analysis,NMR and FAB mass spectra. In the solid state,the Pt(bpt)4 anion receptor adopts a cone conformation to bind the chloride anion through hydrogen bonds and electrostatic interaction in which the four branches of the thiourea ligands bind the chloride anion to form N-H…Cl-hydrogen bonds (3.49-3.81). The entraped chloride anion is situated above the Pt(Ⅱ) center at 3.52 . Further second-sphere coordination assemby from the Pt(bpt)4 core with 8 zinc(Ⅱ) tetraphenylporphyrins (ZnPr) is discussed.

  7. Pendant-armed Unsymmetrical Aza-macrocycles: Syntheses,Coordination Behavior and Crystal Structure of a Dinuclear Cadmium Complex

    Institute of Scientific and Technical Information of China (English)

    TAO,Jing-Chao(陶京朝); LIAO,Xin-Cheng(廖新成); WANG,Xing-Wang(王兴旺); DU,Chen-Xia(杜晨霞)

    2002-01-01

    Two nsymmetrical tetradentate aza-macrocycles with side arms attached to the N3sp atoms, L1 and L2, as well as their complexes with different metal cations were synthesized and characterized by EA, UV, IR, 1H NMR and MS spectra. Both the two ligands can efficiently transport alkali and transition metal cations across an organic membrane with high selectivity ratio. The structure of a dinuclear Cd(Ⅱ)complex [L1@(CdCl2)2] was elucdated by X-ray crystallography and was solved by the heavy-atom method to afinal R value of 0.029 for 3084reflections with |F| >3σ(I). In the exo-structore of the dinuclear complex each cadmium atom is five-coordinated, bonding to three N atoms and two chlorine atoms.

  8. Making oxidation potentials predictable: Coordination of additives applied to the electronic fine tuning of an iron(II) complex

    KAUST Repository

    Haslinger, Stefan

    2014-11-03

    This work examines the impact of axially coordinating additives on the electronic structure of a bioinspired octahedral low-spin iron(II) N-heterocyclic carbene (Fe-NHC) complex. Bearing two labile trans-acetonitrile ligands, the Fe-NHC complex, which is also an excellent oxidation catalyst, is prone to axial ligand exchange. Phosphine- and pyridine-based additives are used for substitution of the acetonitrile ligands. On the basis of the resulting defined complexes, predictability of the oxidation potentials is demonstrated, based on a correlation between cyclic voltammetry experiments and density functional theory calculated molecular orbital energies. Fundamental insights into changes of the electronic properties upon axial ligand exchange and the impact on related attributes will finally lead to target-oriented manipulation of the electronic properties and consequently to the effective tuning of the reactivity of bioinspired systems.

  9. Pendant—armed Unsymmetrical Aza—macrocycles:Syntheses,Coordination Behavior and Crystal Structure of a Dinuclear Cadmium Complex

    Institute of Scientific and Technical Information of China (English)

    陶京朝; 廖新成; 等

    2002-01-01

    Two unsymmetridcal tetradentate aza-macrocycles with side arms attached to whte Nsp3 atoms ,L1 and L2 ,as well as their complexes with different metal cations were synthesized and characterized by EA,UV IR ,1H NMR and MS spectra ,Both the two ligands can efficiently transport alkai and transition metal cations across an organic membrane with high selectivity ratio.The structure of a dinuclear Cd(Ⅱ) complex [L1.(CdCl2)2] was elucidated by X-ray crystallography and was solved by the heavy-atom method to a final R value of 0.029 for 3084 reflections with |F|>3σ(I), In the exo-structure of the dinuclear complex each cadmium atom is five-coordinated,bonding to three N atoms and two chlorine atoms.

  10. Heteroskorpionate Ligands In Coordination Chemistry – Complexes Relevant To Hydrogenation Catalysis, Olefine Epoxidation, And Inhibitor Studies

    OpenAIRE

    Tampier, Stefan

    2012-01-01

    This work focuses on (i) the syntheses and characterisations of various ruthenium(II) complexes bearing the bdmpza ligand, (ii) complexes based on the new bis(3,5-di-tert-butylpyrazol-1-yl)dithioacetato ligand, (iii) complexes based on bispyrazolylacetate esters, and (iv) the syntheses and characteristics of ferrocenyl-substituted ligands derived from bispyrazolylacetic acid and related chelating ligands. Chapter 3.1.2 outlines principle substitution reactions of [Ru(bdmpza)Cl(PPh3)2] (1) [bd...

  11. A new role for RINT-1 in SNARE complex assembly at the trans-Golgi network in coordination with the COG complex.

    Science.gov (United States)

    Arasaki, Kohei; Takagi, Daichi; Furuno, Akiko; Sohda, Miwa; Misumi, Yoshio; Wakana, Yuichi; Inoue, Hiroki; Tagaya, Mitsuo

    2013-09-01

    Docking and fusion of transport vesicles/carriers with the target membrane involve a tethering factor-mediated initial contact followed by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-catalyzed membrane fusion. The multisubunit tethering CATCHR family complexes (Dsl1, COG, exocyst, and GARP complexes) share very low sequence homology among subunits despite likely evolving from a common ancestor and participate in fundamentally different membrane trafficking pathways. Yeast Tip20, as a subunit of the Dsl1 complex, has been implicated in retrograde transport from the Golgi apparatus to the endoplasmic reticulum. Our previous study showed that RINT-1, the mammalian counterpart of yeast Tip20, mediates the association of ZW10 (mammalian Dsl1) with endoplasmic reticulum-localized SNARE proteins. In the present study, we show that RINT-1 is also required for endosome-to-trans-Golgi network trafficking. RINT-1 uncomplexed with ZW10 interacts with the COG complex, another member of the CATCHR family complex, and regulates SNARE complex assembly at the trans-Golgi network. This additional role for RINT-1 may in part reflect adaptation to the demand for more diverse transport routes from endosomes to the trans-Golgi network in mammals compared with those in a unicellular organism, yeast. The present findings highlight a new role of RINT-1 in coordination with the COG complex.

  12. Heme-copper-dioxygen complexes: toward understanding ligand-environmental effects on the coordination geometry, electronic structure, and reactivity.

    Science.gov (United States)

    Halime, Zakaria; Kieber-Emmons, Matthew T; Qayyum, Munzarin F; Mondal, Biplab; Gandhi, Thirumanavelan; Puiu, Simona C; Chufán, Eduardo E; Sarjeant, Amy A N; Hodgson, Keith O; Hedman, Britt; Solomon, Edward I; Karlin, Kenneth D

    2010-04-19

    The nature of the ligand is an important aspect of controlling the structure and reactivity in coordination chemistry. In connection with our study of heme-copper-oxygen reactivity relevant to cytochrome c oxidase dioxygen-reduction chemistry, we compare the molecular and electronic structures of two high-spin heme-peroxo-copper [Fe(III)O(2)(2-)Cu(II)](+) complexes containing N(4) tetradentate (1) or N(3) tridentate (2) copper ligands. Combining previously reported and new resonance Raman and EXAFS data coupled to density functional theory calculations, we report a geometric structure and more complete electronic description of the high-spin heme-peroxo-copper complexes 1 and 2, which establish mu-(O(2)(2-)) side-on to the Fe(III) and end-on to Cu(II) (mu-eta(2):eta(1)) binding for the complex 1 but side-on/side-on (mu-eta(2):eta(2)) mu-peroxo coordination for the complex 2. We also compare and summarize the differences and similarities of these two complexes in their reactivity toward CO, PPh(3), acid, and phenols. The comparison of a new X-ray structure of mu-oxo complex 2a with the previously reported 1a X-ray structure, two thermal decomposition products respectively of 2 and 1, reveals a considerable difference in the Fe-O-Cu angle between the two mu-oxo complexes ( angleFe-O-Cu = 178.2 degrees in 1a and angleFe-O-Cu = 149.5 degrees in 2a). The reaction of 2 with 1 equiv of an exogenous nitrogen-donor axial base leads to the formation of a distinctive low-temperature-stable, low-spin heme-dioxygen-copper complex (2b), but under the same conditions, the addition of an axial base to 1 leads to the dissociation of the heme-peroxo-copper assembly and the release of O(2). 2b reacts with phenols performing H-atom (e(-) + H(+)) abstraction resulting in O-O bond cleavage and the formation of high-valent ferryl [Fe(IV)=O] complex (2c). The nature of 2c was confirmed by a comparison of its spectroscopic features and reactivity with those of an independently prepared

  13. Catalytic dioxygen activation by Co(II) complexes employing a coordinatively versatile ligand scaffold.

    Science.gov (United States)

    Sharma, Savita K; May, Philip S; Jones, Matthew B; Lense, Sheri; Hardcastle, Kenneth I; MacBeth, Cora E

    2011-02-14

    The ligand bis(2-isobutyrylamidophenyl)amine has been prepared and used to stabilize both mononuclear and dinuclear cobalt(II) complexes. The nuclearity of the cobalt product is regulated by the deprotonation state of the ligand. Both complexes catalytically oxidize triphenylphosphine to triphenylphosphine oxide in the presence of O(2).

  14. Synthesis, spectroscopic, coordination and biological activities of some organometallic complexes derived from thio-Schiff base ligands

    Science.gov (United States)

    Abou-Hussein, Azza A.; Linert, Wolfgang

    2014-01-01

    Two series of mono- and binuclear complexes cyclic or acyclic thio-ferocine Schiff base ligands, derived from the condensation of 2-aminobenzenthiol (L) with monoacetyl ferrocene in the molar ratio 1:1 or in the molar ratio 1:2 for diacetyl ferocine have been prepared. The condensation reactions yield the corresponding Schiff Base ligands, HLa-Maf and H2Lb-Daf. The chelation of the ligands to metal ions occurs through the sulfur of the thiol group as well as the nitrogen atoms of the azomethine group of the ligands. HLa-Maf acts as monobasic bidentate or dibasic tetradentate, while H2Lb-Daf behaves as twice negatively cargend tetradentate ligand. The structures of these ligands were elucidated by elemental analysis, infrared, ultraviolet-visible spectra, as well as 1H NMR spectra. Reactions of the Schiff bases ligands with ruthenium(III), oxovanadium(IV) and dioxouranium(VI) afforded the corresponding transition metal complexes. The properties of the newly prepared complexes were analyse by elemental analyses, infrared, electronic spectra, 1H NMR as well as the magnetic susceptibility and conductivity measurement. The metal complexes exhibits different geometrical arrangements such as octahedral and square pyramidal coordination. Schiff base ligands and their metal complexes were tested against two pathogenic bacteria as Gram-positive and Gram-negative bacteria as well as one kind of fungi to study their biological activity. All the complexes exhibit antibacterial and antifungal activities against these organisms.

  15. Coordination chemistry of sugar-phosphate complexes with palladium(II), rhenium(V) and zinc(II)

    Energy Technology Data Exchange (ETDEWEB)

    Steinborn, Christian Martin

    2013-05-21

    As described before, some studies dealing with coordination chemistry of sugar phosphates are available but no analogous complexes of Zn{sup II} have been investigated yet. The primary goal of this work is, therefore, to fill this gap. In order to stay close to the active sites of enzymes such as class-II-aldolase, the simple metal fragment Zn{sup II}(dien) is used. NMR spectroscopy is used primarily as analytical method since it enables the investigation of both complex equilibria in solution and pH dependence of metal-binding sites. Since this approach is challenging due to the fast metal-ligand exchange and the absence of CIS values, it is necessary to improve the significance of NMR data collected from sugar-phosphate complexes with Zn{sup II}. Hence, further experiments are performed with molecules similar to sugar phosphates such as reducing and methylated sugars or polyols. Beside NMR spectroscopy, crystal-structure analysis will be used to get more detailed information about the binding pattern of the complexes. Additionally, sugar-phosphate complexes of Pd{sup II} are investigated. Further experiments are conducted, on the one hand, to synthesise more sugarphosphate complexes with ReVON2 fragments, and, on the other hand, to grow crystals confirming the theory about mixed sugar-core-phosphate chelation.

  16. Nitrite reduction by a pyridinediimine complex with a proton-responsive secondary coordination sphere.

    Science.gov (United States)

    Kwon, Yubin M; Delgado, Mayra; Zakharov, Lev N; Seda, Takele; Gilbertson, John D

    2016-09-21

    The proton-responsive pyridinediimine ligand, (DEA)PDI (where (DEA)PDI = [(2,6-(i)PrC6H3)(N[double bond, length as m-dash]CMe)(N(Et)2C2H4)(N[double bond, length as m-dash]CMe)C5H3N]) was utilized for the reduction of NO2(-) to NO. Nitrite reduction is facilitated by the protonated secondary coordination sphere coupled with the ligand-based redox-active sites of [Fe(H(DEA)PDI)(CO)2](+) and results in the formation of the {Fe(NO)2}(9) DNIC, [Fe((DEA)PDI)(NO)2](+).

  17. Resolution of P-stereogenic P-heterocycles via the formation of diastereomeric molecular and coordination complexes (a review).

    Science.gov (United States)

    Bagi, Péter; Ujj, Viktória; Czugler, Mátyás; Fogassy, Elemér; Keglevich, György

    2016-02-01

    TADDOL derivatives and the Ca(2+)-salts of tartaric acid derivatives were found to be versatile and generally applicable resolving agents for the preparation of the enantiomers of P-stereogenic heterocyclic phosphine oxides and phosphinates via the formation of the corresponding diastereomeric molecular and coordination complexes. A few of the diastereomeric intermediates were characterized by single crystal X-ray crystallography to gain insights into the binding mode of the corresponding heterocyclic phosphine oxide ("guest") and the resolving agent ("host") and to study the underlying phenomenon of enantiomeric recognition. PMID:26564410

  18. Dynamic Resectorization and Coordination Technology: An Evaluation of Air Traffic Control Complexity

    Science.gov (United States)

    Brinton, Christopher R.

    1996-01-01

    The work described in this report is done under contract with the National Aeronautics and Space Administration (NASA) to support the Advanced Air Transportation Technology (AATR) program. The goal of this program is to contribute to and accelerate progress in Advanced Air Transportation Technologies. Wyndemere Incorporated is supporting this goal by studying the complexity of the Air Traffic Specialist's role in maintaining the safety of the Air Transportation system. It is envisioned that the implementation of Free Flight may significantly increase the complexity and difficulty of maintaining this safety. Wyndemere Incorporated is researching potential methods to reduce this complexity. This is the final report for the contract.

  19. Control of size in losartan/copper(II) coordination complex hydrophobic precipitate.

    Science.gov (United States)

    Denadai, Ângelo M L; Da Silva, Jeferson G; Guimarães, Pedro P G; Gomes, Leonardo Bertolini S; Mangrich, Antonio S; de Rezende, Edivaltrys I P; Daniel, Izabela M P; Beraldo, Heloísa; Sinisterra, Rubén D

    2013-10-01

    Reaction of highly soluble orally active, non-peptide antihypertensive drug losartan with copper(II) leads to the spontaneous formation of a very insoluble 2:1 covalent complex, which self assembles in a hydrophobic supramolecular structure of nanometric dimensions. Thermal analysis showed that Los/Cu(II) complex presents intermediate stability in comparison with its precursors KLos and Cu(OAc)2·H2O. Isothermal titration calorimetry indicated complexation to be a stepwise process, driven by enthalpy and entropy. Zeta potential and DLS measurements showed that it is possible to control the size and charge of nanoprecipitates by adjusting the relative concentration of Los(-) and Cu(II).

  20. A New Polynuclear Coordination Type for (Salicylaldoxime)copper(II) Complexes: Structure and Magnetic Properties of an (Oxime)Cu6 Cluster

    DEFF Research Database (Denmark)

    Wenzel, Marco; Forgan, Ross S.; Faure, Anaëlle;

    2009-01-01

    A previously unseen coordination mode is reported for (salicylaldoxime)copper complexes utilising a linked zwitterionic NO22- donor set. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)......A previously unseen coordination mode is reported for (salicylaldoxime)copper complexes utilising a linked zwitterionic NO22- donor set. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)...

  1. Tracking excited-state charge and spin dynamics in iron coordination complexes

    DEFF Research Database (Denmark)

    Zhang, Wenkai; Alonso-Mori, Roberto; Bergmann, Uwe;

    2014-01-01

    Crucial to many light-driven processes in transition metal complexes is the absorption and dissipation of energy by 3d electrons(1-4). But a detailed understanding of such non-equilibrium excited-state dynamics and their interplay with structural changes is challenging: a multitude of excited...... states and possible transitions result in phenomena too complex to unravel when faced with the indirect sensitivity of optical spectroscopy to spin dynamics(5) and the flux limitations of ultrafast X-ray sources(6,7). Such a situation exists for archetypal poly-pyridyl iron complexes, such as [Fe(2...... that these capabilities will make our method a valuable tool for mapping in unprecedented detail the fundamental electronic excited-state dynamics that underpin many useful light-triggered molecular phenomena involving 3d transition metal complexes....

  2. Studies on the Synthesis and Complexing Behavior of Crown Ethers with External Coordination Center

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The synthesis, characterization of five ditopic or tritopic crown compounds were reported in this paper together with the preparation of the corresponding hetero-dinuclear and hetero-trinuclear complexes with different metal cations.

  3. Complexation of Lanthanides with Nitrate at Variable Temperatures: Thermodynamics and Coordination Modes

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Linfeng; Tian, Guoxin

    2008-12-10

    Complexation of neodymium(III) with nitrate was studied at variable temperatures (25, 40, 55 and 70 C) by spectrophotometry and microcalorimetry. The NdNO{sub 3}{sup 2+} complex is weak and becomes slightly stronger as the temperature is increased. The enthalpy of complexation at 25 C was determined by microcalorimetry to be small and positive, (1.5 {+-} 0.2) kJ {center_dot} mol{sup -1}, in good agreement with the trend of the stability constant at variable temperatures. Luminescence emission spectra and lifetime of Eu(III) in nitrate solutions suggest that inner-sphere and bidentate complexes form between trivalent lanthanides (Nd{sup 3+} and Eu{sup 3+}) and nitrate in aqueous solutions. Specific Ion Interaction approach (SIT) was used to obtain the stability constants of NdNO{sub 3}{sup 2+} at infinite dilution and variable temperatures.

  4. Field-induced slow magnetic relaxation in a six-coordinate mononuclear cobalt(II) complex with a positive anisotropy.

    Science.gov (United States)

    Vallejo, Julia; Castro, Isabel; Ruiz-García, Rafael; Cano, Joan; Julve, Miguel; Lloret, Francesc; De Munno, Giovanni; Wernsdorfer, Wolfgang; Pardo, Emilio

    2012-09-26

    The novel mononuclear Co(II) complex cis-[Co(II)(dmphen)(2)(NCS)(2)]·0.25EtOH (1) (dmphen = 2,9-dimethyl-1,10-phenanthroline) features a highly rhombically distorted octahedral environment that is responsible for the strong positive axial and rhombic magnetic anisotropy of the high-spin Co(II) ion (D = +98 cm(-1) and E = +8.4 cm(-1)). Slow magnetic relaxation effects were observed for 1 in the presence of a dc magnetic field, constituting the first example of field-induced single-molecule magnet behavior in a mononuclear six-coordinate Co(II) complex with a transverse anisotropy energy barrier.

  5. Coordination of 1,4-Diazabutadiene Ligands to Decamethylytterbocene: Additional Examples of Spin Coupling in Ytterbocene Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Richard; Walter, Marc D.; Berg, David J.; Andersen, Richard A.

    2006-11-04

    The paramagnetic 1:1 coordination complexes of (C5Me5)2Yb with a series of diazabutadiene ligands, RN=C(R')C(R')=NR, where R= CMe3, CHMe2, adamantyl, p-tolyl, p-anisyl, and mesityl when R'=H, and R= p-anisyl when R'= Me, have been prepared. The complexes are paramagnetic, but their magnetic moments are less than expected for the two uncoupled spin carriers, (C5Me5)2Yb(III, 4f13) and the diazabutadiene radical anions (S=1/2), which implies exchange coupling between the spins. The variable temperature 1H NMR spectra show that rotation about the R-N bond is hindered and these barriers are estimated. The barriers are largely determined by steric effects but electronic effects are not unimportant.

  6. Characteristic differences in the formation of complex coacervate core micelles from neodymium and zinc-based coordination polymers.

    Science.gov (United States)

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

    2007-05-31

    In this paper we compare the formation of complex coacervate core micelles (C3Ms) from two different tricompontent mixtures, namely neodymium, the bisligand L2EO4 and the poly(cation)-block-poly(neutral) diblock copolymer P2MVP41-b-PEO205, and zinc, L2EO4 and P2MVP41-b-PEO205 mixed systems. Three sets of titration experiments were carried out for each system: (i) titration of diblock copolymer P2MVP41-b-PEO205 with the stoichiometric mixture of metal ions and bisligands, (ii) titration of a mixture of diblock copolymer and bisligand with metal ions, and (iii) titration of a mixture of diblock copolymer and metal ions with bisligands. In all the above three cases, micelles are found to form either in a broad range of charge ratios or in a broad range of metal/bisligand ratios. Upon addition of Nd2-(L2EO4)3 coordination polymer to P2MVP41-b-PEO205 solution, and upon addition of Nd3+ to a mixture of L2EO4 and P2MVP41-b-PEO205, micelles are found to form immediately after the first addition, whereas micelles show up in the similar zinc system only after a certain threshold Zn-(L2EO4) or Zn2+ concentration. This difference can be traced to the different structures of the Nd2-(L2EO4)3 and Zn-(L2EO4) coordination compounds. At very low concentrations, Zn-(L2EO4) are ring-like oligomers, but Nd2-(L2EO4)3 are larger networks. The network structure favors the formation of coacervate micellar core with P2MVP41-b-PEO205. Moreover, excess of Nd3+ ions will break up the C3Ms, while the same amount of Zn2+ has hardly any effect on the C3Ms. The breakdown of C3Ms by Nd3+ is due to the charge inversion of the coordination complex with increasing [Nd3+]/[L2EO4] ratio, which results in repulsive interaction between the coordination complex and the diblock copolymer, whereas no such interaction can occur in the zinc system.

  7. Nitrite reduction by a pyridinediimine complex with a proton-responsive secondary coordination sphere.

    Science.gov (United States)

    Kwon, Yubin M; Delgado, Mayra; Zakharov, Lev N; Seda, Takele; Gilbertson, John D

    2016-09-21

    The proton-responsive pyridinediimine ligand, (DEA)PDI (where (DEA)PDI = [(2,6-(i)PrC6H3)(N[double bond, length as m-dash]CMe)(N(Et)2C2H4)(N[double bond, length as m-dash]CMe)C5H3N]) was utilized for the reduction of NO2(-) to NO. Nitrite reduction is facilitated by the protonated secondary coordination sphere coupled with the ligand-based redox-active sites of [Fe(H(DEA)PDI)(CO)2](+) and results in the formation of the {Fe(NO)2}(9) DNIC, [Fe((DEA)PDI)(NO)2](+). PMID:27539064

  8. Solid-state and solution-state coordination chemistry of lanthanide(III) complexes with α-hydroxyisobutyric acid.

    Science.gov (United States)

    Chen, Xiao-Yan; Goff, George S; Ewing, William C; Scott, Brian L; Runde, Wolfgang

    2012-12-17

    Despite the wide range of applications of α-hydroxyisobutyric acid (HIBA) in biochemical processes, pharmaceutical formulations, and group and elemental separations of lanthanides and actinides, the structures and geometries of lanthanide-HIBA complexes are still not well understood. We reacted HIBA with lanthanides in aqueous solution at pH = 5 and synthesized 14 lanthanide-HIBA complexes of the formula [Ln(HIBA)(2)(H(2)O)(2)](NO(3))·H(2)O (Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Tm (12), Yb (13), Lu (14)), isolating single crystals (1-7, 10, and 11) and powders (8, 9, and 12-14). Both single-crystal and powder X-ray diffraction studies reveal a two-dimensional extended structure across the entire lanthanide series. The environment around the eight-coordinated Ln(III) atom is best described as a distorted dodecahedron, where HIBA acts as a monoanionic tridentate ligand with one carboxylato oxygen atom and one hydroxyl oxygen atom chelating to one Ln(III) center. The carboxylato oxygen atom from a second HIBA ligand bridges to a neighboring Ln(III) atom to form a two-dimensional extended structure. While the coordination mode for HIBA is identical across the lanthanide series, three different structure types are found for La, Ce-Ho, and Er-Lu. Solution characterization using (13)C NMR further confirmed a single solution complex under the crystallization conditions. Raman and UV-vis-NIR absorbance and diffuse reflectance spectra of HIBA-Ln(III) complexes were also measured.

  9. Atom transfer as a preparative tool in coordination chemistry. Synthesis and characterization of Cr(V) nitrido complexes of bidentate ligands

    DEFF Research Database (Denmark)

    Birk, Torben; Bendix, Jesper

    2003-01-01

    a mixture of CrV nitrido species with only labile auxiliary ligands. From this solution CrV nitrido complexes with bidentate monoanionic ligands can be obtained in high yields. Five coordinate complexes of 8-hydroxoquinolinate (quin), 1,3-diphenylpropane-1,3-dionate (dbm), and pyrrolidinedithiocarbamate...... = 11.8267(12) Å, ß = 106.528(7)°, V = 1441.7(2) Å3, Z = 4. Complexes 2 and 3 represent new coordination environments for first row transition metal nitrido complexes. The d-orbital energy splitting in these systems with relatively weak equatorial donors differs significantly from the pattern in vanadyl...

  10. Hetero-bimetallic Complex of a 2D Coordination Network Constructed by Sodium Ion and p-Sulfonatothiacalix[4]arene

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A 2D coordination polymer built by sodium ion and water-soluble p-sulfonato thiacalix(4)arene of trivalent yttrium complex [Na(H2O)2Y(H2O)6(DMF) (p-sulfonatothiaca lix(4)arene)]·9H2O is reported.The complex belongs to the monoclinic system, space group P21/c, with a =16.703(3),b = 17.819(4), c = 17.357(4)(A), β= 106.23(3)°,Z= 4,V= 4960.0(17)(A)3, Mr = 1304.08,Dc = 1.746 g/cm3,μ= 1.624 mm-1, F(000) = 2688, the final R = 0.0398 and wR = 0.1132 for 7534 observed reflections with I>2σ(I).One yttrium(Ⅲ) ion is coordinated by the thiacalixarene ligand via the sulfonato group, and also ligated by an oxygen atom of a DMF molecule occupying the cavity of thiacalixarene and six aqua ligands.

  11. Hydrogen Bonds Dictate the Coordination Geometry of Copper: Characterization of a Square-Planar Copper(I) Complex.

    Science.gov (United States)

    Dahl, Eric W; Szymczak, Nathaniel K

    2016-02-24

    6,6''-Bis(2,4,6-trimethylanilido)terpyridine (H2Tpy(NMes)) was prepared as a rigid, tridentate pincer ligand containing pendent anilines as hydrogen bond donor groups in the secondary coordination sphere. The coordination geometry of (H2 Tpy(NMes))copper(I)-halide (Cl, Br and I) complexes is dictated by the strength of the NH-halide hydrogen bond. The Cu(I)Cl and Cu(II)Cl complexes are nearly isostructural, the former presenting a highly unusual square-planar geometry about Cu(I) . The geometric constraints provided by secondary interactions are reminiscent of blue copper proteins where a constrained geometry, or entatic state, allows for extremely rapid Cu(I)/Cu(II) electron-transfer self-exchange rates. Cu(H2 Tpy(NMes))Cl shows similar fast electron transfer (≈10(5)  m(-1)  s(-1)) which is the same order of magnitude as biological systems.

  12. Synthesis, structures and properties of a series of manganese coordination complexes constructed from dicarboxylic fluorene derivatives

    International Nuclear Information System (INIS)

    Assembly reactions of 9,9-diethylfluorene-2,7-dicarboxylic acid (H2DFDC) and Mn(CH3COO)2·4H2O or MnCl2·4H2O by tuning of various secondary ligands such as 2,2′-bipyridine (2,2′-bpy), 4,4′-bipyridine (4,4′-bpy) or 1,3-bis(4-pyridyl)propane) (bpp), gave rise to four complexes { [Mn2(DFDC)2(DMF)2]·H2O} n (1), [Mn(DFDC)(2,2′-bpy)]n (2), { [Mn2(DFDC)2(4,4′-bpy)2]·2CH3OH} n (3), and { [Mn4(DFDC)4(bpp)2(CH3OH)3 (H2O)3]·3(CH3OH)·3(H2O)} n (4). Single crystal X-ray diffraction analysis reveal that complex 1 is three dimensional structure with rhombic channels filled by guest water molecules; 2 presents a close-packed structure with high thermal stability; 3 exhibits a three dimensional framework with micro-porous channels filled by guest methanol molecules and 4 is a two-dimensional structure. The photoluminescent properties of 1–4 have been studied, respectively, showing that the Mn(II) ions, accessorial organic ligands or crystal structures exert important influences on the photoluminescence emissions of H2DFDC ligands. Thermogravimetric analysis show that the complexes have remarkably high thermal stability. Magnetic susceptibility measurements have been finished and discussed for the complexes. - Graphical abstract: Assembly of 9,9-diethylfluorene-2,7-dicarboxylic acid and Mn(II) salts by tuning of various accessorial ligands resulted in four manganese complexes with different topological frameworks. Highlights: ► Four manganese complexes based on 9,9-diethylfluorene-2,7-dicarboxylic acid were obtained. ► The complexes were structurally characterized by single-crystal X-ray diffraction. ► The complexes 1–4 display different topological structures. ► Thermogravimetric analysis show the complexes have remarkably high thermal stability.

  13. Multidisciplinary management of pregnancy in complex congenital heart disease: a model for coordination of care.

    Science.gov (United States)

    Harris, Rachel C; Fries, Melissa H; Boyle, Annelee; Adeniji-Adele, Hassan; Cherian, Zacharia; Klein, Nancy; John, Anitha S

    2014-01-01

    With advancements in medical care, many women with complex congenital heart disease (CHD) are now living into adulthood and childbearing years. The strains of pregnancy and parturition can be dangerous in such patients, and careful interdisciplinary plans must be made to optimize maternal and fetal health through this process. Several large studies have been published regarding risk prediction and medical management of pregnancy in complex CHD, though few case studies detailing clinical care plans have been published. The objective of this report is to describe the process of developing a detailed pregnancy and delivery care plan for three women with complex CHD, including perspectives from the multidisciplinary specialists involved in the process. This article demonstrates that collaboration between specialists in the fields of cardiology, anesthesiology, high-risk obstetrics, maternal fetal medicine, and neonatology results in clinically successful individualized treatment plans for the management of pregnancy in complex CHD. Multidisciplinary collaboration is a crucial element in the management of pregnancy in complex CHD. We provide a template used in three cases which can serve as a model for the design of future care plans.

  14. Theoretical Studies on the Spin Exchange Interaction in Copper(II) Complexes Coordinated with Nitronyl Nitroxide

    Institute of Scientific and Technical Information of China (English)

    Jie REN; Hai Yan WEI; Qi Hua ZHAO; Zhi Da CHEN

    2003-01-01

    Nitronyl nitroxide radical 1, NIT (4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide) and copper(II) chloride complexes with nitronyl nitroxide 2, [Cu(NITPh)2Cl2] (NITPh=2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) were studied with density functional theory (DFT). The magnetic orbital analysis reveals that the antiferromagnetic coupling for complex 2 is due to the antibonding σ*-orbital overlap between (Cu) and π* (NO) orbitals. Also, spin population and atomic charge distribution analysis suggest that for AFS of complex 2 the antiferromagnetic coupling between the radical ligands and the copper(II) ion originates from the spin delocalization induced by the α electron transfer from π*(NO) to (Cu) orbital.

  15. School Nurses and Care Coordination for Children with Complex Needs: An Integrative Review

    Science.gov (United States)

    McClanahan, Rachel; Weismuller, Penny C.

    2015-01-01

    Health care for students with chronic needs can be complex and specialized, resulting in fragmentation, duplication, and inefficiencies. Students who miss school due to chronic conditions lose valuable educational exposure that contributes to academic success. As health-related disabilities increase in prevalence so does the need for the…

  16. The DASH complex and Klp5/Klp6 kinesin coordinate bipolar chromosome attachment in fission yeast.

    Science.gov (United States)

    Sanchez-Perez, Isabel; Renwick, Steven J; Crawley, Karen; Karig, Inga; Buck, Vicky; Meadows, John C; Franco-Sanchez, Alejandro; Fleig, Ursula; Toda, Takashi; Millar, Jonathan B A

    2005-08-17

    We identified a truncated allele of dam1 as a multicopy suppressor of the sensitivity of cdc13-117 (cyclin B) and mal3-1 (EB-1) cells to thiabendazole, a microtubule poison. We find that Dam1 binds to the plus end of spindle microtubules and kinetochores as cells enter mitosis and this is dependent on other components of the fission yeast DASH complex, including Ask1, Duo1, Spc34 and Dad1. By contrast, Dad1 remains bound to kinetochores throughout the cell cycle and its association is dependent on the Mis6 and Mal2, but not Mis12, Nuf2 or Cnp1, kinetochore proteins. In cells lacking Dam1, or other components of the DASH complex, anaphase is delayed due to activation of the spindle assembly checkpoint and lagging sister chromatids are frequently observed and occasionally sister chromatid pairs segregate to the same spindle pole. We find that the mitotic centromere-associated Klp5/Klp6 kinesin complex is essential in cells lacking components of the DASH complex. Cells lacking both Dam1 and Klp5 undergo a first cell cycle arrest in mitosis due to a failure to establish bipolar chromosome attachment. PMID:16079915

  17. Crystal structures of bis- and hexakis[(6,6′-dihydroxybipyridinecopper(II] nitrate coordination complexes

    Directory of Open Access Journals (Sweden)

    Deidra L. Gerlach

    2015-12-01

    Full Text Available Two multinuclear complexes synthesized from Cu(NO32 and 6,6′-dihydroxybipyridine (dhbp exhibit bridging nitrate and hydroxide ligands. The dinuclear complex (6,6′-dihydroxybipyridine-2κ2N,N′[μ-6-(6-hydroxypyridin-2-ylpyridin-2-olato-1:2κ3N,N′:O2](μ-hydroxido-1:2κ2O:O′(μ-nitrato-1:2κ2O:O′(nitrato-1κOdicopper(II, [Cu2(C10H7N2O2(OH(NO32(C10H8N2O2] or [Cu(6-OH-6′-O-bpy(NO3(μ-OH(μ-NO3Cu(6,6′-dhbp], (I, with a 2:1 ratio of nitrate to hydroxide anions and one partially deprotonated dhbp ligand, forms from a water–ethanol mixture at neutral pH. The hexanuclear complex bis(μ3-bipyridine-2,2′-diolato-κ3O:N,N′:O′tetrakis(6,6′-dihydroxybipyridine-κ2N,N′tetrakis(μ-hydroxido-κ2O:O′bis(methanol-κOtetrakis(μ-nitrato-κ2O:O′hexacopper(II, [Cu6(C10H6N2O22(CH4O2(OH4(NO34(C10H8N2O24] or [Cu(6,6′-dhbp(μ-NO32(μ-OHCu(6,6′-O-bpy(μ-OHCu(6,6′dhbp(CH3OH]2, (II, with a 1:1 NO3–OH ratio and two fully protonated and fully deprotonated dhbp ligands, was obtained by methanol recrystallization of material obtained at pH 3. Complex (II lies across an inversion center. Complexes (I and (II both display intramolecular O—H...O hydrogen bonding. Intermolecular O—H...O hydrogen bonding links symmetry-related molecules forming chains along [100] for complex (I with π-stacking along [010] and [001]. Complex (II forms intermolecular O—H...O hydrogen-bonded chains along [010] with π-stacking along [100] and [001].

  18. pH-Dependent Assembly and Conversions of Six Cadmium(II)-Based Coordination Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Hua-Cai; Zhu, Ji-Qin; Zhou, Li-Jiang; Jia, Hong-Yang; Li, Shan-Shan; Gong, Xue; Li, Shu-Bin; Cai, Yue-Peng; Thallapally, Praveen K.; Liu, Jun; Exarhos, Gregory J.

    2010-07-07

    Six cadmium(II) complexes containing N2O2 donor tetradentate asymmetrical Schiff base ligand 2-{[2-(dimethylamino)ethylimino]methyl}-6-methoxyphenol (HL5), namely, [(Cd3L52Cl4)2]•CH3OH•H2O (1), [Cd(L5)Cl]2•CH3OH (2), [Cd2(HL5)Cl4]n (3), {[Cd3(H2L5)2Cl8]•2H2O}n (4), [(H2L5)2]2+•[CdCl4]2-•H2O (5), and [(H2L5)2]2+•[CdCl4]2- (6), have been synthesized using cadmium(II) chloride and asymmetrical Schiff base ligand HL5 under different pH conditions at room temperature. The diverse structures show the marked sensitivity of the structural chemistry of the tetradentate asymmetrical Schiff base ligand HL5. Complex 1 formed at pH = 10 exhibits a rare zero- dimensional structure of trinuclear cadmium (II). At pH = 8-9, a dinuclear cadmium (II) complex 2 is formed. The reaction at pH = 5-7 leads to two one-dimensional structures of 3 and 4. A further decrease of the pH to 3-5 results in a zero-dimensional structure 5. Owing to the departure of lattice water molecules in the crystal, complex 5 at room temperature can gradually undergo single-crystal-to-single-crystal transformation to result complex 6. The results further show that conversions of complex 1 to 5 can also be achieved by adjusting the pH value of the reaction solution, 1→2pH=8→5pH=3 and 3→4pH=5. Comparing these experimental results, it is clear that the pH plays a crucial role in the formation of the resulting structures, which simultaneously provide very effective strategies for constructing the CdII compounds with N2O2 donor tetradentate asymmetrical Schiff base ligand. The strong fluorescent emissions of the six compounds (1-6) make them potentially useful photoactive materials. Furthermore, six Schiff base cadmium complexes (1–6), with DPPH (2,2-dipheny1-1-picrylhydrazy1) as a co-oxidant exhibited the stronger scavenging activity.

  19. Osmium and cobalt complexes incorporating facially coordinated N,N,O donor azo-imine ligands: Redox and catalytic properties

    Indian Academy of Sciences (India)

    Poulami Pattanayak; Debprasad Patra; Jahar Lal Pratihar; Andrew Burrows; Mary F Mahon; Surajit Chattopadhyay

    2013-01-01

    Reactions of 1-{[2-(arylazo)phenyl]iminomethyl}-2-phenol, HL [where H represents the dissociable phenolic protons of ligands and aryl groups of HL are C6H5 (HL1), -CH3C6H5 (HL2), -ClC6H5 (HL3)] with Os(H)(CO)(Br)(PPh3)3 in toluene and with Co(ClO4)3.6H2O in methanol afforded new facially coordinated complexes of composition [(L)Os(CO)(Br)(PPh3)] and [(L)2Co]ClO4. The anionic ligand (L)−, binds the metal in tridentate (N, N, O) manner in [(L)Os(CO)(Br)(PPh3)] and [(L)2Co]ClO4 complexes. All the Os(II) and Co(III) complexes are diamagnetic and show characteristic 1H NMR signals and intense MLCT transitions in the visible region. The cyclic voltammograms exhibited one quasi reversible oxidative response near 0.10 V vs SCE for [(L)Os(CO)(Br)(PPh3)] and [(L)2Co]ClO4 complexes displayed serial reductive responses within −0.06 to −1.61 V vs SCE. Single point DFT calculation was carried out to examine the nature of redox orbitals. Conversion of ketones to corresponding alcohols has been studied using [(L)Os(CO)(Br)(PPh3)] as catalyst.

  20. Chelate-Thiolate-Coordinate Ligands Modulating the Configuration and Electrochemical Property of Dinitrosyliron Complexes (DNICs).

    Science.gov (United States)

    Yeh, Shih-Wey; Lin, Chih-Wei; Liu, Bai-Heng; Tsou, Chih-Chin; Tsai, Ming-Li; Liaw, Wen-Feng

    2015-11-01

    As opposed to the reversible redox reaction ({Fe(NO)2 }(10) reduced-form DNIC [(NO)2 Fe(S(CH2 )3 S)](2-) (1)⇌{Fe(NO)2 }(9) oxidized-form [(NO)2 Fe(S(CH2 )3 S)](-) ), the chemical oxidation of the {Fe(NO)2 }(10) DNIC [(NO)2 Fe(S(CH2 )2 S)](2-) (2) generates the dinuclear {Fe(NO)2 }(9) -{Fe(NO)2 }(9) complex [(NO)2 Fe(μ-SC2 H4 S)2 Fe(NO)2 ](2-) (3) bridged by two terminal [SC2 H4 S](2-) ligands. On the basis of the Fe K-edge pre-edge energy and S K-edge XAS, the oxidation of complex 1 yielding [(NO)2 Fe(S(CH2 )3 S)](-) is predominantly a metal-based oxidation. The smaller S1-Fe1-S2 bond angle of 94.1(1)° observed in complex 1 (S1-Fe1-S2 88.6(1)° in complex 2), compared to the bigger bond angle of 100.9(1)° in the {Fe(NO)2 }(9) DNIC [(NO)2 Fe(S(CH2 )3 S)](-) , may be ascribed to the electron-rich {Fe(NO)2 }(10) DNIC preferring a restricted bite angle to alleviate the electronic donation of the chelating thiolate to the electron-rich {Fe(NO)2 }(10) core. The extended transition state and natural orbitals for chemical valence (ETS-NOCV) analysis on the edt-/pdt-chelated {Fe(NO)2 }(9) and {Fe(NO)2 }(10) DNICs demonstrates how two key bonding interactions, that is, a FeS covalent σ bond and thiolate to the Fe d z 2 charge donation, between the chelating thiolate ligand and the {Fe(NO)2 }(9/10) core could be modulated by the backbone lengths of the chelating thiolate ligands to tune the electrochemical redox potential (E1/2 =-1.64 V for complex 1 and E1/2 =-1.33 V for complex 2) and to dictate structural rearrangement/chemical transformations (S-Fe-S bite angle and monomeric vs. dimeric DNICs).

  1. Evolving dynamics of trading behavior based on coordination game in complex networks

    Science.gov (United States)

    Bian, Yue-tang; Xu, Lu; Li, Jin-sheng

    2016-05-01

    This work concerns the modeling of evolvement of trading behavior in stock markets. Based on the assumption of the investors' limited rationality, the evolution mechanism of trading behavior is modeled according to the investment strategy of coordination game in network, that investors are prone to imitate their neighbors' activity through comprehensive analysis on the risk dominance degree of certain investment behavior, the network topology of their relationship and its heterogeneity. We investigate by mean-field analysis and extensive simulations the evolution of investors' trading behavior in various typical networks under different risk dominance degree of investment behavior. Our results indicate that the evolution of investors' behavior is affected by the network structure of stock market and the effect of risk dominance degree of investment behavior; the stability of equilibrium states of investors' behavior dynamics is directly related with the risk dominance degree of some behavior; connectivity and heterogeneity of the network plays an important role in the evolution of the investment behavior in stock market.

  2. Cationic terminal gallylene complexes by halide abstraction: coordination chemistry of a valence isoelectronic analogue of CO and N2.

    Science.gov (United States)

    Coombs, Natalie D; Vidovic, Dragoslav; Day, Joanna K; Thompson, Amber L; Le Pevelen, Delphine D; Stasch, Andreas; Clegg, William; Russo, Luca; Male, Louise; Hursthouse, Michael B; Willock, David J; Aldridge, Simon

    2008-11-26

    While N(2) and CO have played central roles in developing models of electronic structure, and their interactions with transition metals have been widely investigated, the valence isoelectronic diatomic molecules EX (E = group 13 element, X = group 17 element) have yet to be isolated under ambient conditions, either as the "free" molecule or as a ligand in a simple metal complex. As part of a program designed to address this deficiency, together with wider issues of the chemistry of cationic systems [L(n)M(ER)](+) (E = B, Al, Ga; R = aryl, amido, halide), we have targeted complexes of the type [L(n)M(GaX)](+). Halide abstraction is shown to be a viable method for the generation of mononuclear cationic complexes containing gallium donor ligands. The ability to isolate tractable two-coordinate products, however, is strongly dependent on the steric and electronic properties of the metal/ligand fragment. In the case of complexes containing ancillary pi-acceptor ligands such as CO, cationic complexes can only be isolated as base-trapped adducts, even with bulky aryl substituents at gallium. Base-free gallylene species such as [Cp*Fe(CO)(2)(GaMes)](+) can be identified only in the vapor phase by electrospray mass spectrometry experiments. With bis(phosphine) donor sets at the metal, the more favorable steric/electronic environment allows for the isolation of two-coordinate ligand systems, even with halide substituents at gallium. Thus, [Cp*Fe(dppe)(GaI)](+)[BAr(f)(4)](-) (9) can be synthesized and shown crystallographically to feature a terminally bound GaI ligand; 9 represents the first experimental realization of a complex containing a valence isoelectronic group 13/group 17 analogue of CO and N(2). DFT calculations reveal a relatively weakly bound GaI ligand, which is confirmed experimentally by the reaction of 9 with CO to give [Cp*Fe(dppe)(CO)](+)[BAr(f)(4)](-). In the absence of such reagents, 9 is stable for weeks in fluorobenzene solution, presumably reflecting (i

  3. Coordinated aqua vs methanol substitution kinetics in fac-Re(I) tricarbonyl tropolonato complexes.

    Science.gov (United States)

    Schutte, Marietjie; Roodt, Andreas; Visser, Hendrik G

    2012-11-01

    Water-soluble fac-[Re(CO)(3)(L,L'-Bid)(X)] (L,L'-Bid = tropolonato, X = H(2)O, methanol) complexes have been synthesized, and the aqua and methanol substitution reactions were investigated in water (pH range 6.3-10.0) and methanol, respectively, and compared. Thiocyanate ions were used as monodentate entering ligand. The complexes were characterized by UV-vis, IR, and NMR spectroscopy. The crystal structures of the complexes [NEt(4)] fac-[Re(Trop)(CO)(3)(H(2)O)].NO(3).H(2)O (reactant) and fac-[Re(CO)(3)(Trop)(Py)], a substitution product, are reported. Overall it was found that the aqua substitution of fac-[Re(CO)(3)(Trop)(H(2)O)] is about 10 times faster than the methanol substitution reaction for fac-[Re(CO)(3)(Trop)(MeOH)], with forward and reverse rate and stability constants [k(1) (M(-1) s(-1)), k(-1) (s(-1)), K(1), (M(-1))] for thiocyanate as monodentate entering ligand as follows: fac-[Re(CO)(3)(Trop)(H(2)O)] = 2.54 ± 0.03, 0.0077 ± 0.0005, 330 ± 22/207 ± 14 and fac-[Re(CO)(3)(Trop)(MeOH)] = 0.268 ± 0.002, 0.0044 ± 0.0002, (61 ± 3)/(52 ± 4). The activation parameters [ΔH(‡)(k1) (kJ mol(-1)), ΔS(‡)(k1) (J K(-1) mol(-1))] for the aqua and methanol complex respectively are 56.1 ± 0.7, -49 ± 2 and 64 ± 1, -43 ± 5. PMID:23088314

  4. Spontaneous Partitioning of Californium from Curium: Curious Cases from the Crystallization of Curium Coordination Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Cary, Samantha K.; Silver, Mark A.; Liu, Guokui; Wang, Jamie C.; Bogart, Justin A.; Stritzinger, Jared T.; Arico, Alexandra A.; Hanson, Kenneth; Schelter, Eric J.; Albrecht-Schmitt, Thomas E.

    2015-12-07

    The reaction of 248CmCl3 with excess 2,6-pyridinedicarboxylic acid (DPA) under mild solvothermal conditions results in crystallization of the tris-chelate complex Cm(HDPA)3·H2O. Approximately half of the curium remains in solution at the end of this process, and evaporation of the mother liquor results in crystallization of the bis-chelate complex [Cm(HDPA)- (H2DPA)(H2O)2Cl]Cl·2H2O. 248Cm is the daughter of the α decay of 252Cf and is extracted in high purity from this parent. However, trace amounts of 249,250,251Cf are still present in all samples of 248Cm. During the crystallization of Cm(HDPA)3·H2O and [Cm(HDPA)(H2DPA)(H2O)2Cl]Cl·2H2O, californium(III) spontaneously separates itself from the curium complexes and is found doped within crystals of DPA in the form of Cf(HDPA)3. These results add to the growing body of evidence that the chemistry of californium is fundamentally different from that of earlier actinides.

  5. Simultaneous end-on/side-on coordination modes of a diphosphorus tetrahedral complex imposed by pre-organization of oligometallic Cu(I) acceptors.

    Science.gov (United States)

    Welsch, Stefan; Lescop, Christophe; Balazs, Gabor; Réau, Régis; Scheer, Manfred

    2011-08-01

    The reaction of the [{CpMo(CO)(2)}(2)(μ,η(2):η(2)-P(2))] (Cp=cyclopentadienyl) metallo-ligand 2 with pre-organized Cu(I) bi- and trimetallic precursors afforded new coordination complexes with unprecedented coordination modes for a Mo(2)P(2) complex. Variable-temperature solution and solid-state (31)P NMR spectroscopy measurements were performed and X-ray diffraction studies revealed an η(2):η(1) coordination mode for the Mo(2)P(2) unit of 2 in the Cu(I) bimetallic complexes 3 and 4. DFT calculations were carried out to highlight the bonding situation of this unprecedented coordination mode in the Cu(I) bimetallic compound 3. It is built up from a side-on coordination of the P-P σ bond to one copper ion and from the interaction of the lone pair of one phosphorus atom with the second copper ion. The remaining available lone pair of the second phosphorus atom can be involved as well to interact with an additional metal centre, as evidenced in the Cu(I) trimetallic compound 5 in which an η(2):η(1):η(1) coordination mode of the ligand 2 is observed. Derivative 3 can be used as a molecular clip to obtain discrete π-stacked dimers through a ligand exchange reaction between acetonitrile ligands and cyano-capped π-conjugated systems, indicating the stability of the new η(2):η(1) coordination mode.

  6. System Coordination of Survivability and Safety of Complex Engineering Objects Operation

    Directory of Open Access Journals (Sweden)

    Nataliya Pankratova

    2014-11-01

    Full Text Available A system strategy to estimation the guaranteed survivability and safety of complex engineering objects (CEO operation is proposed. The principles that underlie the strategy of the guaranteed safety of CEO operation provide a flexible approach to timely detection, recognition, forecast, and system diagnostics of risk factors and situations, to formulation and implementation of a rational decision in a practicable time within an unremovable time constraint. Implementation of the proposed strategy is shown on example of diagnostics of electromobile-refrigerator functioning in real mode.

  7. The DASH complex and Klp5/Klp6 kinesin coordinate bipolar chromosome attachment in fission yeast

    OpenAIRE

    Sanchez-Perez, Isabel; Renwick, Steven J; Crawley, Karen; Karig, Inga; Buck, Vicky; Meadows, John C; Franco-Sanchez, Alejandro; Fleig, Ursula; Toda, Takashi; Millar, Jonathan B. A.

    2005-01-01

    We identified a truncated allele of dam1 as a multicopy suppressor of the sensitivity of cdc13-117 (cyclin B) and mal3-1 (EB-1) cells to thiabendazole, a microtubule poison. We find that Dam1 binds to the plus end of spindle microtubules and kinetochores as cells enter mitosis and this is dependent on other components of the fission yeast DASH complex, including Ask1, Duo1, Spc34 and Dad1. By contrast, Dad1 remains bound to kinetochores throughout the cell cycle and its association is depende...

  8. Complex Coordination of Cell Plasticity by a PGC-1α-controlled Transcriptional Network in Skeletal Muscle.

    Science.gov (United States)

    Kupr, Barbara; Handschin, Christoph

    2015-01-01

    Skeletal muscle cells exhibit an enormous plastic capacity in order to adapt to external stimuli. Even though our overall understanding of the molecular mechanisms that underlie phenotypic changes in skeletal muscle cells remains poor, several factors involved in the regulation and coordination of relevant transcriptional programs have been identified in recent years. For example, the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) is a central regulatory nexus in the adaptation of muscle to endurance training. Intriguingly, PGC-1α integrates numerous signaling pathways and translates their activity into various transcriptional programs. This selectivity is in part controlled by differential expression of PGC-1α variants and post-translational modifications of the PGC-1α protein. PGC-1α-controlled activation of transcriptional networks subsequently enables a spatio-temporal specification and hence allows a complex coordination of changes in metabolic and contractile properties, protein synthesis and degradation rates and other features of trained muscle. In this review, we discuss recent advances in our understanding of PGC-1α-regulated skeletal muscle cell plasticity in health and disease.

  9. Complex coordination of cell plasticity by a PGC-1α-controlled transcriptional network in skeletal muscle

    Directory of Open Access Journals (Sweden)

    Barbara eKupr

    2015-11-01

    Full Text Available Skeletal muscle cells exhibit an enormous plastic capacity in order to adapt to external stimuli. Even though our overall understanding of the molecular mechanisms that underlie phenotypic changes in skeletal muscle cells remains poor, several factors involved in the regulation and coordination of relevant transcriptional programs have been identified in recent years. For example, the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α is a central regulatory nexus in the adaptation of muscle to endurance training. Intriguingly, PGC-1α integrates numerous signaling pathways and translates their activity into various transcriptional programs. This selectivity is in part controlled by differential expression of PGC-1α variants and post-translational modifications of the PGC-1α protein. PGC-1α-controlled activation of transcriptional networks subsequently enables a spatio-temporal specification and hence allows a complex coordination of changes in metabolic and contractile properties, protein synthesis and degradation rates and other features of trained muscle. In this review, we discuss recent advances in our understanding of PGC-1α-regulated skeletal muscle cell plasticity in health and disease.

  10. Catenation control in the two-dimensional coordination polymers based on tritopic carboxylate linkers and azamacrocyclic nickel(II) complexes.

    Science.gov (United States)

    Lampeka, Yaroslaw D; Tsymbal, Liudmyla V; Barna, Andrij V; Shuĺga, Yulija L; Shova, Sergiu; Arion, Vladimir B

    2012-04-14

    Four new coordination polymer frameworks, namely [(NiL(1))(3)(BTB)(2)]·6H(2)O, [(NiL(2))(3)(BTB)(2)]·6H(2)O, [(NiL(3))(3)(BTB)(2)]·6H(2)O and [(NiL(2))(3)(BTC)(2)]·10.25H(2)O (L(1) = 1,4,8,11-tetraazacyclotetradecane, L(2) = 3-methyl-1,3,5,8,12-pentaazacyclotetradecane, L(3) = 3,10-dimethyl-1,3,5,8,10,12-hexaazacyclotetradecane, BTC(3-) = benzene-1,3,5-tricarboxylate, BTB(3-) = 4,4',4''-benzene-1,3,5-triyl-tribenzoate) were prepared in water-N,N-dimethylformamide solutions. The molecular and crystal structures of these compounds are compared to the related coordination polymers formed by nickel(II) macrocyclic cations to examine the effect of carboxylate linker size on the framework architecture. Luminescent properties of the complexes based on the BTB(3-) bridging ligand are also discussed. PMID:22266979

  11. Two lanthanum(III) complexes containing η2-pyrazolate and η2-1,2,4-triazolate ligands: intramolecular C-H...N/O interactions and coordination geometries.

    Science.gov (United States)

    Wang, Yu-Long; Feng, Meng; Tao, Xian; Tang, Qing-Yun; Shen, Ying-Zhong

    2013-01-01

    The lanthanum(III) complexes tris(3,5-diphenylpyrazolato-κ(2)N,N')tris(tetrahydrofuran-κO)lanthanum(III) tetrahydrofuran monosolvate, [La(C(15)H(11)N(2))(3)(C(4)H(8)O)(3)]·C(4)H(8)O, (I), and tris(3,5-diphenyl-1,2,4-triazolato-κ(2)N(1),N(2))tris(tetrahydrofuran-κO)lanthanum(III), [La(C(14)H(10)N(3))(3)(C(4)H(8)O)(3)], (II), both contain La(III) atoms coordinated by three heterocyclic ligands and three tetrahydrofuran ligands, but their coordination geometries differ. Complex (I) has a mer-distorted octahedral geometry, while complex (II) has a fac-distorted configuration. The difference in the coordination geometries and the existence of asymmetric La-N bonding in the two complexes is associated with intramolecular C-H...N/O interactions between the ligands.

  12. Coordination complexes of niobium and tantalum pentahalides with a bulky NHC ligand.

    Science.gov (United States)

    Bortoluzzi, Marco; Ferretti, Eleonora; Marchetti, Fabio; Pampaloni, Guido; Zacchini, Stefano

    2016-04-28

    The 1 : 1 molar reactions of niobium and tantalum pentahalides with the monodentate NHC ligand 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (Ipr), in toluene (or benzene) at ca. 80 °C, afforded the complexes NbX5(Ipr) (X = F, ; Br, ) and TaX5(Ipr) (X = F, ; Cl, ; Br, ), in generally good yields. Complexes represent uncommon cases of stable NHC adducts of metal halides with the metal in an oxidation state higher than +4, and also rare examples of Nb-NHC and Ta-NHC bonding systems. In particular, the X-ray molecular structure determined for provides the unprecedented crystallographic characterization of a tantalum compound with a monodentate NHC ligand. DFT results indicate that the metal-carbon bond in is a purely σ one. According to NMR studies ((1)H, (13)C, (93)Nb), the formation of , , , as well as the previously communicated NbCl5(Ipr), , proceeded with the intermediacy of [MX6](-) salts, presumably due to steric reasons. On the other hand, the intermediate formation of MF6(-) in the pathways to and was not observed, according to (19)F (and (93)Nb in the case of ) NMR. DFT calculations were carried out in order to shed light on structural and mechanistic aspects, and allowed to trace possible reaction routes. PMID:26982241

  13. Photodynamics in stable complexes composed of a zinc porphyrin tripod and pyridyl porphyrins assembled by multiple coordination bonds.

    Science.gov (United States)

    Takai, Atsuro; Gros, Claude P; Barbe, Jean-Michel; Fukuzumi, Shunichi

    2010-10-14

    A tripod zinc porphyrin (TPZn(3)) forms a stable 1:1 complex with gold(III) tetra(4-pyridyl)porphyrin (AuTPyP(+)) and free-base tris(4-pyridyl)porphyrin (2H-Py(3)P) in nonpolar solvents. The strong binding of TPZn(3) with AuTPyP(+) or 2H-Py(3)P results from the encapsulation of AuTPyP(+) or 2H-Py(3)P inside the cavity of TPZn(3) through multiple coordination bonds, as indicated by UV-vis-NIR, ESI-MS, (1)H NMR, electrochemistry and computational studies. The binding constants of monomer zinc porphyrin (MPZn) with AuTPyP(+) and 2H-Py(3)P drastically decrease as compared with TPZn(3). Detailed photophysical studies have been carried out on these composites using laser flash photolysis as well as emission spectroscopy. The efficient quenching of the singlet excited state of TPZn(3) occurs via a photoinduced electron-transfer pathway in the TPZn(3)-AuTPyP(+) complex. In contrast, energy transfer occurs in the TPZn(3)-2H-Py(3)P complex due to the smaller driving force of the photoinduced electron-transfer pathway. Neither electron transfer nor energy transfer occurs from MPZn to AuTPyP(+) under the same experimental conditions due to the small association constant of the monomer zinc porphyrin. PMID:20714588

  14. Effect of pH on complex coacervate core micelles from Fe(III)-based coordination polymer.

    Science.gov (United States)

    Wang, Junyou; de Keizer, Arie; van Leeuwen, Herman P; Yan, Yun; Vergeldt, Frank; van As, Henk; Bomans, Paul H H; Sommerdijk, Nico A J M; Cohen Stuart, Martien A; van der Gucht, Jasper

    2011-12-20

    The effect of pH on iron-containing complex coacervate core micelles [Fe(III)-C3Ms] is investigated in this paper. The Fe(III)-C3Ms are formed by mixing cationic poly(N-methyl-2-vinylpyridinium iodide)-b-poly(ethylene oxide) [P2MVP(41)-b-PEO(205)] and anionic iron coordination polymers [Fe(III)-L(2)EO(4)] at stoichiometric charge ratio. Light scattering and Cryo-TEM have been performed to study the variations of hydrodynamic radius and core structure with changing pH. The hydrodynamic radius of Fe(III)-C3Ms is determined mainly by the corona and does not change very much in a broad pH range. However, Cryo-TEM pictures and magnetic relaxation measurements indicate that the structure of the micellar cores changes upon changing the pH, with a more crystalline, elongated shape and lower relaxivity at high pH. We attribute this to the formation of mixed iron complexes in the core, involving both the bis-ligand and hydroxide ions. These complexes are stabilized toward precipitation by the diblock copolymer.

  15. A new arene-Ru based supramolecular coordination complex for efficient binding and selective sensing of green fluorescent protein.

    Science.gov (United States)

    Mishra, Anurag; Ravikumar, Sambandam; Song, Young Ho; Prabhu, Nadarajan Saravanan; Kim, Hyunuk; Hong, Soon Ho; Cheon, Seyeon; Noh, Jaegeun; Chi, Ki-Whan

    2014-04-28

    A new dipyridyl ligand is encoded with 120° angularity between its coordination vectors by using a central pyridine carboxamide scaffold to orient two 4-(pyridin-4-ylethynyl)phenyl moieties. The N,N'-bis(4-(pyridin-4-ylethynyl)phenyl)pyridine-2,6-dicarboxamide ligand undergoes self-assembly with a diruthenium arene complex to furnish a [2 + 2] metallacycle with a wedge-like structure. The metallacycle binds to the enhanced green fluorescent protein (EGFP) variant of GFP, resulting in steady-state spectral changes in UV-Vis absorption and emission experiments. These studies indicate that the metallacycle induces conformation changes to the EGFP, disrupting the tripeptide chromophore. Furthermore, gel electrophoresis, circular dichroism and atomic force microscopy studies indicate that binding ultimately leads to aggregation of the protein. Computational investigations indicate a favorable interaction, predominantly between the metallacycle and the Arg168 residue of the EGFP. An interaction with Arg168 and related residues was previously observed for an emission-attenuating antibody, supporting that these interactions induce changes to the photophysical properties of EGFP by disrupting the tripeptidechromophore in a similar manner. Additionally, we have also described the quenching study of the reporter GFP protein in vivo by a new metal complex using reflected fluorescence microscopy. We anticipate that such metal complexes which can passively diffuse into the cells in vivo can serve as potential tools in molecular and drug targeting based biological studies.

  16. Restoring Lands - Coordinating Science, Politics and Action Complexities of Climate and Governance

    CERN Document Server

    Scarlett, Lynn; Vargas-Moreno, Juan; Flaxman, Michael

    2012-01-01

    Environmental issues, vast and varied in their details, unfold at the confluence of people and place. They present complexities in their biophysical details, their scope and scale, and the dynamic character of human action and natural systems. Addressing environmental issues often invokes tensions among battling interests and competing priorities. Air and water pollution, the effects of climate change, ecosystem transformations—these and other environmental issues involve scientific, social, economic, and institutional challenges. This book analyzes why tackling many of these problems is so difficult and why sustainability involves more than adoption of greener, cleaner technologies. Sustainability, as discussed in this book, involves knowledge flows and collaborative decision processes that integrate scientific and technological methods and tools, political and governance structures and regimes, and social and community values. The authors synthesize a holistic and adaptive approach to rethinking the frame...

  17. Using Learning Automata in Coordination Among Heterogeneous Agents in a Complex Multi-Agent Domain

    Directory of Open Access Journals (Sweden)

    Mohammadreza Khojasteh

    2012-06-01

    Full Text Available This paper describes our use of Learning Automata as a reinforcement learning method incoordination among three heterogeneous teams of agents acting in RoboCup Rescue Simulationenvironment. We provide a brief introduction to Learning Automata and Cellular LearningAutomata, the reinforcement machine learning methods that we have used in lots of parts of ouragents’ development. Then we will describe the major challenges each team of agents should beconcerned about in such a complex domain and for each challenge, we propose our approachesto develop cooperative teams. Finally, some results of using Learning Automata in coordinatingthese heterogeneous teams of agents that cooperate to mitigate the disastrous damages in asimulated city are evaluated.

  18. Freeze-drying synthesis of an amorphous Zn(2+) complex and its transformation to a 2-D coordination framework in the solid state.

    Science.gov (United States)

    Itakura, T; Horike, S; Inukai, M; Kitagawa, S

    2016-03-14

    An amorphous and metastable precursor for a Zn two-dimensional coordination framework was synthesised via freeze drying. The precursor comprises randomly packed discrete clusters of a Zn complex. The amorphous-to-crystalline framework transformation, which was triggered by the gentle application of heat or pressure, was accompanied by a change in the coordination geometry of the Zn(2+) ions from tetrahedral to octahedral symmetry.

  19. Two mechanisms coordinate replication termination by the Escherichia coli Tus–Ter complex

    KAUST Repository

    Pandey, Manjula

    2015-07-13

    The Escherichia coli replication terminator protein (Tus) binds to Ter sequences to block replication forks approaching from one direction. Here, we used single molecule and transient state kinetics to study responses of the heterologous phage T7 replisome to the Tus–Ter complex. The T7 replisome was arrested at the non-permissive end of Tus–Ter in a manner that is explained by a composite mousetrap and dynamic clamp model. An unpaired C(6) that forms a lock by binding into the cytosine binding pocket of Tus was most effective in arresting the replisome and mutation of C(6) removed the barrier. Isolated helicase was also blocked at the non-permissive end, but unexpectedly the isolated polymerase was not, unless C(6) was unpaired. Instead, the polymerase was blocked at the permissive end. This indicates that the Tus–Ter mechanism is sensitive to the translocation polarity of the DNA motor. The polymerase tracking along the template strand traps the C(6) to prevent lock formation; the helicase tracking along the other strand traps the complementary G(6) to aid lock formation. Our results are consistent with the model where strand separation by the helicase unpairs the GC(6) base pair and triggers lock formation immediately before the polymerase can sequester the C(6) base.

  20. Ammonia Binding in the Second Coordination Sphere of the Oxygen-Evolving Complex of Photosystem II.

    Science.gov (United States)

    Vinyard, David J; Askerka, Mikhail; Debus, Richard J; Batista, Victor S; Brudvig, Gary W

    2016-08-01

    Ammonia binds to two sites in the oxygen-evolving complex (OEC) of Photosystem II (PSII). The first is as a terminal ligand to Mn in the S2 state, and the second is at a site outside the OEC that is competitive with chloride. Binding of ammonia in this latter secondary site results in the S2 state S = (5)/2 spin isomer being favored over the S = (1)/2 spin isomer. Using electron paramagnetic resonance spectroscopy, we find that ammonia binds to the secondary site in wild-type Synechocystis sp. PCC 6803 PSII, but not in D2-K317A mutated PSII that does not bind chloride. By combining these results with quantum mechanics/molecular mechanics calculations, we propose that ammonia binds in the secondary site in competition with D1-D61 as a hydrogen bond acceptor to the OEC terminal water ligand, W1. Implications for the mechanism of ammonia binding via its primary site directly to Mn4 in the OEC are discussed. PMID:27433995

  1. Engineering and Coordination of Regulatory Networks and Intracellular Complexes to Maximize Hydrogen Production by Phototrophic Microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    James C. Liao

    2012-05-22

    This project is a collaboration with F. R. Tabita of Ohio State. Our major goal is to understand the factors and regulatory mechanisms that influence hydrogen production. The organisms to be utilized in this study, phototrophic microorganisms, in particular nonsulfur purple (NSP) bacteria, catalyze many significant processes including the assimilation of carbon dioxide into organic carbon, nitrogen fixation, sulfur oxidation, aromatic acid degradation, and hydrogen oxidation/evolution. Our part of the project was to develop a modeling technique to investigate the metabolic network in connection to hydrogen production and regulation. Organisms must balance the pathways that generate and consume reducing power in order to maintain redox homeostasis to achieve growth. Maintaining this homeostasis in the nonsulfur purple photosynthetic bacteria is a complex feat with many avenues that can lead to balance, as these organisms possess versatile metabolic capabilities including anoxygenic photosynthesis, aerobic or anaerobic respiration, and fermentation. Growth is achieved by using H{sub 2} as an electron donor and CO{sub 2} as a carbon source during photoautotrophic and chemoautotrophic growth, where CO{sub 2} is fixed via the Calvin-Benson-Bassham (CBB) cycle. Photoheterotrophic growth can also occur when alternative organic carbon compounds are utilized as both the carbon source and electron donor. Regardless of the growth mode, excess reducing equivalents generated as a result of oxidative processes, must be transferred to terminal electron acceptors, thus insuring that redox homeostasis is maintained in the cell. Possible terminal acceptors include O{sub 2}, CO{sub 2}, organic carbon, or various oxyanions. Cells possess regulatory mechanisms to balance the activity of the pathways which supply energy, such as photosynthesis, and those that consume energy, such as CO{sub 2} assimilation or N{sub 2} fixation. The major route for CO{sub 2} assimilation is the CBB

  2. Photoinduced intercalation and coordination of a dirhodium complex to DNA: dual DNA binding.

    Science.gov (United States)

    Palmer, Alycia M; Burya, Scott J; Gallucci, Judith C; Turro, Claudia

    2014-06-01

    Two new complexes, cis-H,H-[Rh2 (OCCH3 NH)2 (LL)(CH3 CN)2 ](2+) , where LL=bpy (2, bpy=2,2'-bipyridine) and dppz (3, dppz=dipyrido[3,2-a:2',3'-c]phenazine), were prepared from the reaction of cis-H,H-[Rh2 (OCCH3 NH)2 (CH3 CN)6 ](2+) (1) with the corresponding bidentate ligand. The bpy and dppz ligands chelate to the same rhodium atom and are positioned trans to the amidato N atoms, as determined by the single crystal X-ray structure of 2. Irradiation of 2 and 3 with visible light in water results in the exchange of one CH3 CNeq ligand for an H2 O molecule with quantum yields, Φ400 , of 0.040 and 0.044, respectively (λirr =400 nm). The identities of the photoproducts of 2 and 3 were determined to be cis-H,H-[Rh2 (OCCH3 NH)2 (L)(H2 O)(CH3 CN)](2+) , where L is bpy (4) and dppz (5), respectively. Mobility shift assays show that 4 crosslinks double-stranded DNA, and ESI-MS experiments indicate that both 4 and 5 form covalent adducts with single-stranded DNA. In addition, relative viscosity and 2D NMR experiments show that the dppz ligand of 5 also intercalates into DNA upon irradiation, making 3 a dual-binding agent that both intercalates and covalently binds to DNA upon the absorption of visible light.

  3. Coordination Complexes of Decamethylytterbocene with4,4'-Disubstituted Bipyridines: An Experimental Study of Spin Coupling inLanthanide Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Marc D.; Berg, David J.; Andersen, Richard A.

    2005-12-08

    The paramagnetic 1:1 coordination complexes of (C5Me5)2Ybwith a series of 4,4'-disubstituted bipyridines, bipy-X, where X is Me,tert-Bu, OMe, Ph, CO2Me, and CO2Et have been prepared. All of thecomplexes are paramagnetic and the values of the magnetic susceptibilityas a function of temperature show that these values are less thanexpected for the cation, [(C5Me5)2Yb(III)(bipy-X)]+, which have beenisolated as the cation-anion ion-pairs[(C5Me5)2Yb(III)(bipy-X)]+[(C5Me5)2YbI2]f fnfn where X is CO2Et, OMe andMe. The 1H NMR chemical shifts (293 K) for the methine resonances locatedat the 6,6' site in the bipy-X ring show a linear relationship with thevalues of chiT (300 K) for the neutral complexes which illustrates thatthe molecular behavior does not depend upon the phase with one exception,viz., (C5Me5)2Yb(bipy-Me). Single crystals of the 4,4'-dimethylbipyridinecomplex undergo an irreversible, abrupt first order phase change at 228 Kthat shatters the single crystals. The magnetic susceptibility,represented in a delta vs. T plot, on this complex, in polycrystallineform undergoes reversible abrupt changes in the temperature regime 205 -212 K, which is suggested to be due to the way the individual molec ularunits pack in the unit cell. A qualitative model is proposed thataccounts for the sub-normal magnetic moments in theseytterbocene-bipyridine complexes.

  4. [trans-en2Os(η-H2)]2+ as an 1H NMR probe for the coordination of some anticancer metal complexes to deoxyguanotide

    Institute of Scientific and Technical Information of China (English)

    杨频; 郭茂林; 李青山; 田燕妮; Henry TAUBE

    1997-01-01

    The molecular hydrogen complex of osmium,[trans-en2Os(η-H2)]2+(en,entlylendediamine) is a new 1H NMR recognition probe for biomolecules.By using this probe,the coordination between deoxyguanylic acid (dGMP) and four metal anticancer complexes,titanocene dichloride,(C2H5)2SnCl2(phen),(C2H5)2SnCl2 and cis-piatm are studied in D2O under the condition near the physiological one.The results show that the former three complexes mainly and strongly coordinate with the phosphate oxygen of dGMP,while cisplatin mainly coordinates with N(7) of dGMP

  5. Bowl adamanzanes-bicyclic tetraamines: syntheses and crystal structures of complexes with cobalt(III) and chelating coordinated oxo-anions

    DEFF Research Database (Denmark)

    Broge, Louise; Søtofte, Inger; Jensen, Kristian;

    2007-01-01

    complex is provided. Four of the seven complexes contain a chelate coordinating oxo-anion ( sulfate, formiate, nitrate, carbonate). Equilibration of these species with the corresponding diaqua complex is generally slow. The rates of equilibration in 5 mol dm(-3) perchloric acid at 25 degrees C have been...... been measured to K-a = 0.33 mol dm(-3) [ 25 degrees C, I = 2 mol dm(-3)] and K-a = 0.15 mol dm(-3) [ 25 degrees C, I = 5 mol dm(-3)]. The propensity for coordination of sulfate was found to be large enough for a quantitative conversion of the carbonato complex to the sulfato complex to occur in 3 mol...... for the complexes of the larger [ 3(5)] adz ligand. The high af. nity for chelating coordination of oxo-anions for these two cobalt( III)-adamanzane-moieties is rationalised on basis of the N-Co-N angles. N-Co-N angles are compared for a series of adamanzane complexes, and the structural consequences are discussed....

  6. 从配位体到配位络合物结构:扫描隧道显微学的分子工程%From ligands to coordinated complex architectures:a molecular engineering with scanning tunneling microscopy

    Institute of Scientific and Technical Information of China (English)

    万立骏

    2006-01-01

    @@ With the development of modem coordination chemistry,various metal-ligand complexes with elaborate structures have been synthesized.[1]The structural complexities as well as the coordination processes of these metal-ligand complexes can be partially comparable to those in biology system formed by self-assembling with the weak intermolecular or intramolecular interactions.

  7. Syntheses and Structural Researches of Yb3+ Complexes with Nitrilotriacetic Acids--Nine-coordinate K3[Yb(nta)2(H2O)]·5H2O and Eight-coordinate Na3[Yb(nta)2]·6H2O Complexes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Yb3+ complexes with two nitrilotriacetic acid molecules were prepared and their compositions were determined as K3[Yb(nta)2(H2O)]*5H2O and Na3[Yb(nta)2]*6H2O by elemental analyses. Their structures were characterized by single-crystal X-ray diffraction analyses. In complex K3[Yb(nta)2(H2O)]*5H2O, the YbN2O7 part forms a nine-coordinate monocapped square antiprismatic structure. In complex Na3[Yb(nta)2]*6H2O, the YbN2O6 part forms an eight-coordinate square antiprismatic structure. It can be seen that the outer cations (K+ and Na+) greatly affect the coordination number and coordinate structure from these results.

  8. Crystal structures of copper(II) complexes of 2-formylpyridine substituted thiosemicarbazones; the first example of a coordinated thiosemicarbazone with a thiol function

    Science.gov (United States)

    West, D. X.; Swearingen, J. K.; Romack, T. J.; Billeh, I. S.; Jasinski, J. P.; Li, Y.; Staples, R. J.

    2001-08-01

    The crystal structures of two 5-coordinate copper(II) complexes containing neutral, tridentate 2-formylpyridine N(4)-substituted thiosemicarbazones have been determined. 2-Formylpyridine N(4)-cyclohexylthiosemicarbazone, HFo4CHex coordinates via the pyridine nitrogen, imine nitrogen and thione sulfur with two chloro ligands to produce [Cu(HFo4CHex)Cl 2]. Similarly, 2-formylpyridine 3-(4-methylpiperazine)thiosemicarbazone, HFoppz4M, produces [Cu(HFoppz4M)Cl 2] with one major difference; rather than the expected thione form of the thiosemicarbazone moiety, it coordinates as the thiol isomer. Both complexes are close to a square pyramid structure with axial and equatorial chloro ligands and the thiosemicarbazone moieties of both ligands nearly planar. Also included is the crystal structure of N-cyclohexylthiosemicarbazide, CHextsc.

  9. Separation performance of cucurbit[8]uril and its coordination complex with cadmium (II) in capillary gas chromatography.

    Science.gov (United States)

    Sun, Tao; Ji, Ningning; Qi, Meiling; Tao, Zhu; Fu, Ruonong

    2014-05-23

    Here we report the investigation of using cucurbit[8]uril (CB8) and its coordination complex with cadmium (II) (CB8-Cd) as stationary phases for capillary gas chromatography (GC). The prepared capillary columns of CB8 and CB8-Cd stationary phases achieved column efficiency of 2200plates/m and 1508plates/m, respectively, and showed weak polarity based on the measured McReynolds constants. Their separation performance was investigated by GC separation of mixtures of different types while a commercial column was used for comparison. The CB8 stationary phase achieved high resolution for a wide range of analytes from nonpolar to polar while the CB8-Cd stationary phase exhibited good separation mainly for nonpolar to weak polar analytes. The CB stationary phases differ from the commercial one in terms of retention behaviors and resolving ability due to their different molecular interactions with analytes. Moreover, energy effect on the retention of analytes on CB8 and CB8-Cd stationary phases was examined, showing that retention on CB8 column was determined mainly by enthalpy change for polar analytes and by both enthalpy change and entropy change for weak polar analytes whereas retention on CB8-Cd column was mainly controlled by entropy change. This work demonstrates the great potential of CB8 and CB8-Cd stationary phases as a new type of GC stationary phases in GC analysis.

  10. Tetrapositive plutonium, neptunium, uranium, and thorium coordination complexes: chemistry revealed by electron transfer and collision induced dissociation.

    Science.gov (United States)

    Gong, Yu; Tian, Guoxin; Rao, Linfeng; Gibson, John K

    2014-04-17

    The Pu(4+), Np(4+), and U(4+) ions, which have large electron affinities of ∼34.6, ∼33.6, and ∼32.6 eV, respectively, were stabilized from solution to the gas phase upon coordination by three neutral tetramethyl-3-oxa-glutaramide ligands (TMOGA). Both collision induced dissociation (CID) and electron transfer dissociation (ETD) of Pu(TMOGA)3(4+) reveal the propensity for reduction of Pu(IV) to Pu(III), by loss of TMOGA(+) in CID and by simple electron transfer in ETD. The reduction of Pu(IV) is in distinct contrast to retention of Th(IV) in both CID and ETD of Th(TMOGA)3(4+), where only the C-Oether bond cleavage product was observed. U(TMOGA)3(4+) behaves similarly to Th(TMOGA)3(4+) upon CID and ETD, while the fragmentation patterns of Np(TMOGA)3(4+) lie between those of Pu(TMOGA)3(4+) and U(TMOGA)3(4+). It is notable that the gas-phase fragmentation behaviors of these exceptional tetrapositive complexes parallel fundamental differences in condensed phase chemistry within the actinide series, specifically the tendency for reduction from the IV to III oxidation states.

  11. Tetrapositive plutonium, neptunium, uranium, and thorium coordination complexes: chemistry revealed by electron transfer and collision induced dissociation.

    Science.gov (United States)

    Gong, Yu; Tian, Guoxin; Rao, Linfeng; Gibson, John K

    2014-04-17

    The Pu(4+), Np(4+), and U(4+) ions, which have large electron affinities of ∼34.6, ∼33.6, and ∼32.6 eV, respectively, were stabilized from solution to the gas phase upon coordination by three neutral tetramethyl-3-oxa-glutaramide ligands (TMOGA). Both collision induced dissociation (CID) and electron transfer dissociation (ETD) of Pu(TMOGA)3(4+) reveal the propensity for reduction of Pu(IV) to Pu(III), by loss of TMOGA(+) in CID and by simple electron transfer in ETD. The reduction of Pu(IV) is in distinct contrast to retention of Th(IV) in both CID and ETD of Th(TMOGA)3(4+), where only the C-Oether bond cleavage product was observed. U(TMOGA)3(4+) behaves similarly to Th(TMOGA)3(4+) upon CID and ETD, while the fragmentation patterns of Np(TMOGA)3(4+) lie between those of Pu(TMOGA)3(4+) and U(TMOGA)3(4+). It is notable that the gas-phase fragmentation behaviors of these exceptional tetrapositive complexes parallel fundamental differences in condensed phase chemistry within the actinide series, specifically the tendency for reduction from the IV to III oxidation states. PMID:24660979

  12. Variable coordinating activity of sulfur in silver(I) complexes with thiophene based N¹ -substituted thiosemicarbazones: First case of thiopheneyl-thione sulfur bridging in a dinuclear complex

    Indian Academy of Sciences (India)

    REKHA SHARMA; TARLOK S LOBANA; MANVIR KAUR; NEERAJ THATHAI; GEETA HUNDAL; JERRY P JASINSKI; RAY J BUTCHER

    2016-07-01

    Thiophene-2-carbaldehyde / acetaldehyde-N¹-substituted thiosemicarbazones {R¹R²C² = N³ - N(H)- C¹(=S)N¹HR; R¹, R², R : C₄H₃S, H, Me, Httsc- NMe; C₄H₃S, H, Et, Httsc-NEt; C₄H₃S, H, Ph, Httsc-NPh; C₄H₃S, Me, Et, Hattsc-NEt} and furan-2-carbaldehyde-N-ethyl thiosemicarbazone (C₄H₃O, H, Et, Hftsc-NEt) were reacted with silver(I) halides/silver(I) acetate in presence of triphenylphosphine in organic solvents. These reactions yielded a series of dinuclear [Ag₂(μ-Br)₂ (κ-S-Httsc-NEt)2(PPh3)2]·2MeOH 1, [Ag2Cl2(κ1-SHttsc-NPh)2(μ-S,S-Httsc-NPh)2] 2, [Ag2Cl2(μ-S-Hftsc-NEt)2(κ1-S-Hftsc-NEt)2] 4, [Ag2(μ3-N3,S-ttsc-NMe)2 (Ph3P)2]·2(CH3)2CO 5, [Ag2 (μ3-N3,S-attsc-NEt)2(Ph3P)2]·0.5(CH3)2CO 6 and mononuclear [AgBr(κ1-SHttsc-NPh)(PPh3)2]· MeCN 3 complexes, all of which have been characterized using analytical techniques, IRand NMR spectroscopy, and X-ray crystallography. Thio-ligands bind in neutral form in complexes 1-4 and in anionic form in complexes 5-6. Further, the sulfur donor atoms have shown variable coordination modes incomplexes, namely, κ1-S in 1 and 3; κ1-S, μ-S in 4; κ1-S, μ-S,S (thiopheneyl-thione) in 2 and μ3- N3, S in 5 and 6. Tertiary-phosphine (PPh3) showed dual function of ligation/de-ligation towards silver(I) chloride during the synthesis of complexes 2 and 4. The bridge bonding of Httsc-NPh in 2 through thiopheneyl ring sulfur andthione sulfur is unprecedented in metal-thiosemicarbazone chemistry.

  13. ESI-MS and theoretical study on the coordination structures and reaction modes of the diperoxovanadate complexes containing histidine-like ligands

    Science.gov (United States)

    Yu, Xian-Yong; Xu, Xin; Chen, Zhong

    2008-01-01

    In order to study the coordination structures and the reaction modes of diperoxovanadate complexes in the gas phase, the interaction between K3[OV(O2)2(C2O4)]·H2O and a series of histidine-like ligands has been investigated by the combination of the electrospray ionization-mass spectrometry (ESI-MS) and the density functional theory (DFT) calculations. The experimental results proved the formation of both [OV(O2)2L]- (L = all histidine-like ligands) and [OV(O2)2L'2]- (L' = histidine and carnosine only) species. DFT calculations at the level of B3LYP/6-31+G* showed that [OV(O2)2L'2]- is a hexa-coordinated complex, instead of a hepta-coordinated complex as proposed before. The unique coordination mode in the gas phase is for one ligand to bind to the oxygen atoms via hydrogen binding, rather than both ligands to the metal center. The L'2 dimer formation and the maintenance of the hydrogen bonding within the dimer during the complex formation are two important factors that enhance the abundance of the [OV(O2)2L'2]- species. The calculated bonding enthalpy and free energy changes provided an explanation on the reaction modes of the interaction systems, in agreement with the observations of the ESI-MS experiments.

  14. Coordination complexes of the tungsten(VI) oxide fluorides WOF4 and WO2F2 with neutral oxygen and nitrogen donor ligands

    OpenAIRE

    Reid, Gillian; Levason, William; Zhang, Wenjian

    2016-01-01

    Supplementary NMR and IR spectroscopic data for the paper in Journal of Fluorine chemistry Coordination complexes of the tungsten(VI) oxide fluorides WOF4 and WO2F2 with neutral oxygen and nitrogen donor ligands William Levason, Gillian Reid and Wenjian Zhang. Journal of Fluorine chemistry DOI: 10.1016/j.jfluchem.2016.02.003

  15. A new coordination mode of (E)-3-(3-hydroxyl-phenyl)-acrylic acid in copper complex: Crystal structure and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Xin; Zhou, Pei; Zheng, Chunying [Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry, Beijing Institute of Technology, Beijing 100081 (China); Li, Hui, E-mail: lihui@bit.edu [Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry, Beijing Institute of Technology, Beijing 100081 (China)

    2015-05-15

    A copper complex ([Cu(py){sub 2}(L){sub 2}]·2CH{sub 3}OH){sub n} (HL=(E)-3-(3-hydroxyl-phenyl)-acrylic acid) (1) with acrylic acid ligand was synthesized and structurally analyzed by IR, elemental analysis, TGA and the single-crystal X-ray diffraction methods. It is the first time to find that phenolic hydroxyl of L coordinates to Cu(II). Complex 1 exhibits 1D chain by a double-bridge of ligands, and the 3D supramolecular framework in complex 1 is constructed by π–π stacking interactions and van der Waals Contacts among the 1D chains. The magnetic properties of complex 1 have been studied. - Graphical abstract: A copper complex based on (E)-3-(3-hydroxyl-phenyl)-acrylic acid in a novel coordinated way was synthesized and a ferromagnetic exchange interactions between neighboring Cu(II) ions has be achieved. - Highlights: • A new copper complex with acrylic acid ligand was synthesized and analyzed. • We find the phenolic hydroxyl of MCA ligand coordinates to metal ion firstly. • A ferromagnetic exchange interactions between Cu(II) ions has been achieved.

  16. A novel binuclear copper complex incorporating a nalidixic acid derivative displaying a one-dimensional coordination polymeric structure.

    Science.gov (United States)

    Bergamini, F R G; Ribeiro, M A; Miranda, P C M L; Formiga, A L B; Corbi, P P

    2016-07-01

    The identification of the antibacterial action of nalidixic acid (nx) was central to the development of the quinolone antibacterial compounds. The ability of the nx naphthyridyl ring to interact with and inhibit some proteins has encouraged the investigation of similar structures in the search for more active compounds with less adverse effects. The possibility of structural modification by attachment of other biologically active moieties to the naphthyridyl ring of nx allowed the development of new active antimicrobial molecules. Hydrazone derivatives of nx can be synthesized easily based on the condensation of the hydrazide derivative of nx with the desired aldehyde or ketone. Only a few complexes with nx hydrazone derivatives have been described but for none were the crystal structures elucidated. The synthesis of a new one-dimensional Cu(II) coordination polymer, namely catena-poly[[copper(II)-di-μ-chlorido-copper(II)-{μ-1-ethyl-N'-[(1H-imidazol-4-yl)methylidene]-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbohydrazidato}-[dimethanolcopper(II)]-{μ-1-ethyl-N'-[(1H-imidazol-3-yl)methylidene]-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbohydrazidato}] dichloride methanol tetrasolvate], {[Cu3(C16H15N6O2)2Cl2(CH3OH)2]Cl2·4CH3OH}n, with the (1H-imidazol-4-yl)methylidene carbohydrazide derivative of nalidixic acid (denoted h4imi), is presented and its structure is compared to the density functional theory (DFT) optimized structure of free h4imi. The title structure presents an octahedral Cu(II) ion on an inversion centre alternating along a polymer chain with a square-pyramidal Cu(II) ion, with the two Cu(II) centres bridged by two chloride ligands. Hydrogen bonds involving chloride counter-ions and methanol solvent molecules mediate the three-dimensional packing of the polymer. Comparison of the geometrical results from the structure analysis with those derived from a DFT study of the free ligand reveal the differences that arise upon coordination.

  17. A novel binuclear copper complex incorporating a nalidixic acid derivative displaying a one-dimensional coordination polymeric structure.

    Science.gov (United States)

    Bergamini, F R G; Ribeiro, M A; Miranda, P C M L; Formiga, A L B; Corbi, P P

    2016-07-01

    The identification of the antibacterial action of nalidixic acid (nx) was central to the development of the quinolone antibacterial compounds. The ability of the nx naphthyridyl ring to interact with and inhibit some proteins has encouraged the investigation of similar structures in the search for more active compounds with less adverse effects. The possibility of structural modification by attachment of other biologically active moieties to the naphthyridyl ring of nx allowed the development of new active antimicrobial molecules. Hydrazone derivatives of nx can be synthesized easily based on the condensation of the hydrazide derivative of nx with the desired aldehyde or ketone. Only a few complexes with nx hydrazone derivatives have been described but for none were the crystal structures elucidated. The synthesis of a new one-dimensional Cu(II) coordination polymer, namely catena-poly[[copper(II)-di-μ-chlorido-copper(II)-{μ-1-ethyl-N'-[(1H-imidazol-4-yl)methylidene]-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbohydrazidato}-[dimethanolcopper(II)]-{μ-1-ethyl-N'-[(1H-imidazol-3-yl)methylidene]-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbohydrazidato}] dichloride methanol tetrasolvate], {[Cu3(C16H15N6O2)2Cl2(CH3OH)2]Cl2·4CH3OH}n, with the (1H-imidazol-4-yl)methylidene carbohydrazide derivative of nalidixic acid (denoted h4imi), is presented and its structure is compared to the density functional theory (DFT) optimized structure of free h4imi. The title structure presents an octahedral Cu(II) ion on an inversion centre alternating along a polymer chain with a square-pyramidal Cu(II) ion, with the two Cu(II) centres bridged by two chloride ligands. Hydrogen bonds involving chloride counter-ions and methanol solvent molecules mediate the three-dimensional packing of the polymer. Comparison of the geometrical results from the structure analysis with those derived from a DFT study of the free ligand reveal the differences that arise upon coordination

  18. Solid-state and solution-state coordination chemistry of lanthanide(III) complexes with (pyrazol-1-yl)acetic acid.

    Science.gov (United States)

    Chen, Xiao-Yan; Goff, George S; Scott, Brian L; Janicke, Michael T; Runde, Wolfgang

    2013-03-18

    As a precursor of carboxyl-functionalized task-specific ionic liquids (TSILs) for f-element separations, (pyrazol-1-yl)acetic acid (L) can be deprotonated as a functionalized pyrazolate anion to coordinate with hard metal cations. However, the coordination chemistry of L with f-elements remains unexplored. We reacted L with lanthanides in aqueous solution at pH = 5 and synthesized four lanthanide complexes of general formula [Ln(L)3(H2O)2]·nH2O (1, Ln = La, n = 2; 2, Ln = Ce, n = 2; 3, Ln = Pr, n = 2; 4, Ln = Nd, n = 1). All complexes were characterized by single crystal X-ray diffraction analysis revealing one-dimensional chain formations. Two distinct crystallographic structures are governed by the different coordination modes of carboxylate groups in L: terminal bidentate and bridging tridentate (1-3); terminal bidentate, bridging bidentate, and tridentate coordination in 4. Comparison of the solid state UV-vis-NIR diffuse reflectance spectra with solution state UV-vis-NIR spectra suggests a different species in solution and solid state. The different coordination in solid state and solution was verified by distinctive (13)C NMR signals of the carboxylate groups in the solid state NMR.

  19. Preparation and Reactions of the 1,1-Dithiolato Complexes of Ni(II). An Undergraduate Coordination Chemistry Experiment.

    Science.gov (United States)

    Ballester, L.; Perpinan, M. F.

    1988-01-01

    Described is an undergraduate coordination chemistry experiment that enables students to relate concepts developed in class about the stereochemistry and coordination numbers to the interpretation of the electronic and infrared spectra and their magnetic behavior. Indicates that thermal decomposition and x-ray diffraction studies can also be…

  20. Design and structure analysis of artificial metalloproteins: selective coordination of His64 to copper complexes with square-planar structure in the apo-myoglobin scaffold.

    Science.gov (United States)

    Abe, Satoshi; Ueno, Takafumi; Reddy, Pattubala A N; Okazaki, Seiji; Hikage, Tatsuo; Suzuki, Atsuo; Yamane, Takashi; Nakajima, Hiroshi; Watanabe, Yoshihito

    2007-06-25

    apo-Myoglobin (apo-Mb) was reconstituted with three copper complexes: CuII(Sal-Phe) (1; Sal-Phe = N-salicylidene-L-phenylalanato), CuII(Sal-Leu) (2; Sal-Leu = N-salicylidene-L-leucinato), and CuII(Sal-Ala) (3; Sal-Ala = N-salicylidene-L-alanato). The crystal structures of 1.apo-Mb (1.65 Angstrom resolution) and 2.apo-Mb (1.8 Angstrom resolution) show that the coordination geometry around the CuII atom in apo-Mb is distorted square-planar with tridentate Sal-X and a Nepsilon atom of His64 in the apo-Mb cavity and the plane of these copper complexes is perpendicular to that of heme. These results suggest that the apo-Mb cavity can hold metal complexes with various coordination geometries.

  1. Solution chemistry of a water-soluble eta2-H2 ruthenium complex: evidence for coordinated H2 acting as a hydrogen bond donor.

    Science.gov (United States)

    Szymczak, Nathaniel K; Zakharov, Lev N; Tyler, David R

    2006-12-13

    The ability of an eta2-H2 ligand to participate in intermolecular hydrogen bonding in solution has long been an unresolved issue. Such species are proposed to be key intermediates in numerous important reactions such as the proton-transfer pathway of H2 production by hydrogenase enzymes. We present the synthesis of several new water-soluble ruthenium coordination complexes including an eta2-H2 complex that is surprisingly inert to substitution by water. The existence of dihydrogen hydrogen bonding (DHHB) was experimentally probed by monitoring the chemical shift of H-bonded Ru-(H2) complexes using NMR spectroscopy, by UV-visible spectroscopy, and by monitoring the rotational dynamics of a hydrogen-bonding probe molecule. The results provide strong evidence that coordinated H2 can indeed participate in intermolecular hydrogen bonding to bulk solvent and other H-bond acceptors. PMID:17147394

  2. Syntheses and Structural Researches of Yb3+ Complexes with Nitrilotriacetic Acids—Nine—coordinate K3[Yb(nta)2(H2O)]·5H2O and Eight—coordinate Na3[Yb(nta)2]·6H2O complexes

    Institute of Scientific and Technical Information of China (English)

    WANGJun; ZHANGXiang-dong; JIAWei-guo; LIHui-fang

    2003-01-01

    Yb3+ complexes with two nitrilotriacetic acid molecules were prepared and their compositions were determined as K3[Yb(nta)2(H2O)]·5H2O and Na3[Yb(nta)2]·6H2O by elemental analyses.Their structures were characterized by single-crystal X-ray diffraction analyses.In complex K3[Yb(nta)2(H2O)]·5H2O,the YbN2O7 part forms a nine-coordinate monocapped square antiprismatic structure.In comples Na3[Yb(nta)2]·6H2O,the YbN2O6 part forms an eight-coordinate square antiprismatic structure.It can be seen that the outer cations(K+ and Na+)greatly affect the coordination number and coordinate structure from these results.

  3. Thiocyanate-Ligated Heterobimetallic {PtM} Lantern Complexes Including a Ferromagnetically Coupled 1D Coordination Polymer.

    Science.gov (United States)

    Guillet, Jesse L; Bhowmick, Indrani; Shores, Matthew P; Daley, Christopher J A; Gembicky, Milan; Golen, James A; Rheingold, Arnold L; Doerrer, Linda H

    2016-08-15

    A series of heterobimetallic lantern complexes with the central unit {PtM(SAc)4(NCS)} have been prepared and thoroughly characterized. The {Na(15C5)}[PtM(SAc)4(NCS)] series, 1 (Co), 2 (Ni), 3 (Zn), are discrete compounds in the solid state, whereas the {Na(12C4)2)}[PtM(SAc)4(NCS)] series, 4 (Co), 5 (Ni), 6 (Zn), and 7 (Mn), are ion-separated species. Compound 7 is the first {PtMn} lantern of any bridging ligand (carboxylate, amide, etc.). Monomeric 1-7 have M(2+), necessitating counter cations that have been prepared as {(15C5)Na}(+) and {(12C4)2Na}(+) variants, none of which form extended structures. In contrast, neutral [PtCr(tba)4(NCS)]∞ 8 forms a coordination polymer of {PtCr}(+) units linked by (NCS)(-) in a zigzag chain. All eight compounds have been thoroughly characterized and analyzed in comparison to a previously reported family of compounds. Crystal structures are presented for compounds 1-6 and 8, and solution magnetic susceptibility measurements are presented for compounds 1, 2, 4, 5, and 7. Further structural analysis of dimerized {PtM} units reinforces the empirical observation that greater charge density along the Pt-M vector leads to more Pt···Pt interactions in the solid state. Four structural classes, one new, of {MPt}···{PtM} units are presented. Solid state magnetic characterization of 8 reveals a ferromagnetic interaction in the {PtCr(NCS)} chain between the Cr centers of J/kB = 1.7(4) K. PMID:27486841

  4. Thiocyanate-Ligated Heterobimetallic {PtM} Lantern Complexes Including a Ferromagnetically Coupled 1D Coordination Polymer.

    Science.gov (United States)

    Guillet, Jesse L; Bhowmick, Indrani; Shores, Matthew P; Daley, Christopher J A; Gembicky, Milan; Golen, James A; Rheingold, Arnold L; Doerrer, Linda H

    2016-08-15

    A series of heterobimetallic lantern complexes with the central unit {PtM(SAc)4(NCS)} have been prepared and thoroughly characterized. The {Na(15C5)}[PtM(SAc)4(NCS)] series, 1 (Co), 2 (Ni), 3 (Zn), are discrete compounds in the solid state, whereas the {Na(12C4)2)}[PtM(SAc)4(NCS)] series, 4 (Co), 5 (Ni), 6 (Zn), and 7 (Mn), are ion-separated species. Compound 7 is the first {PtMn} lantern of any bridging ligand (carboxylate, amide, etc.). Monomeric 1-7 have M(2+), necessitating counter cations that have been prepared as {(15C5)Na}(+) and {(12C4)2Na}(+) variants, none of which form extended structures. In contrast, neutral [PtCr(tba)4(NCS)]∞ 8 forms a coordination polymer of {PtCr}(+) units linked by (NCS)(-) in a zigzag chain. All eight compounds have been thoroughly characterized and analyzed in comparison to a previously reported family of compounds. Crystal structures are presented for compounds 1-6 and 8, and solution magnetic susceptibility measurements are presented for compounds 1, 2, 4, 5, and 7. Further structural analysis of dimerized {PtM} units reinforces the empirical observation that greater charge density along the Pt-M vector leads to more Pt···Pt interactions in the solid state. Four structural classes, one new, of {MPt}···{PtM} units are presented. Solid state magnetic characterization of 8 reveals a ferromagnetic interaction in the {PtCr(NCS)} chain between the Cr centers of J/kB = 1.7(4) K.

  5. Polycations XX: New Monodentate Cationic Ligands and Their Coordination with Ruthenium for the Construction of Complexes Expressing Enhanced Interaction with DNA

    Directory of Open Access Journals (Sweden)

    Leslie Babukutty

    2012-01-01

    Full Text Available Prior investigations from this laboratory concerned with the preparation of new types of organic cations for a variety of biological and nonbiological applications have been extended to the preparation of cation-bearing ligands with nitrogen coordinating sites for use in complexation reactions with ruthenium cores. The syntheses of new cationic ligands as well as ruthenium complexes bearing them are reported here. The introduction of these new types of ligands is intended to provide to the complexes an enhanced ability to interact with DNA, and thereby to have the potential to be enhanced antitumor agents. Preliminary observations of their interactions with DNA are presented.

  6. Novel mononuclear vanadium complexes having pentalene ligands η8-bonded to a single metal atom - a new type of coordination in organometallic chemistry

    International Nuclear Information System (INIS)

    The pronounced folding of the η8-coordinated pentalene ligand along the bond between the two bridgehead carbon atoms is the most prominent structural feature of the vanadium complex 2. This compound and further 18e complexes of this type are readily prepared by the reaction of vanadocene monohalides 1 or their derivatives with dilithium pentalenediide. Although these mononuclear complexes are air-sensitive, they are thermally so stable that they can be sublimed in high vacuum at 80-100 C without decomposition. (orig.)

  7. Novel mononuclear vanadium complexes having pentalene ligands {eta}{sup 8}-bonded to a single metal atom - a new type of coordination in organometallic chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Jonas, K.; Gabor, B.; Mynott, R.; Angermund, K.; Heinemann, O.; Krueger, C. [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany)

    1997-09-01

    The pronounced folding of the {eta}{sup 8}-coordinated pentalene ligand along the bond between the two bridgehead carbon atoms is the most prominent structural feature of the vanadium complex 2. This compound and further 18e complexes of this type are readily prepared by the reaction of vanadocene monohalides 1 or their derivatives with dilithium pentalenediide. Although these mononuclear complexes are air-sensitive, they are thermally so stable that they can be sublimed in high vacuum at 80-100 C without decomposition. (orig.)

  8. Nonoxido V(IV) Complexes: Prediction of the EPR Spectrum and Electronic Structure of Simple Coordination Compounds and Amavadin.

    Science.gov (United States)

    Sanna, Daniele; Sciortino, Giuseppe; Ugone, Valeria; Micera, Giovanni; Garribba, Eugenio

    2016-08-01

    Density functional theory (DFT) calculations of the (51)V hyperfine coupling (HFC) tensor A have been completed for 20 "bare" V(IV) complexes with different donor sets, electric charges, and coordination geometries. Calculations were performed with ORCA and Gaussian software, using functionals BP86, TPSS0, B1LYP, PBE0, B3LYP, B3P, B3PW, O3LYP, BHandHLYP, BHandH, and B2PLYP. Among the basis sets, 6-311g(d,p), 6-311++g(d,p), VTZ, cc-pVTZ, def2-TZVPP, and the "core properties" CP(PPP) were tested. The experimental Aiso and Ai (where i = x or z, depending on the geometry and electronic structure of V(IV) complex) were compared with the values calculated by DFT methods. The results indicated that, based on the mean absolute percentage deviation (MAPD), the best functional to predict Aiso or Ai is the double hybrid B2PLYP. With this functional and the basis set VTZ, it is possible to predict the Aiso and Az of the EPR spectrum of amavadin with deviations of -1.1% and -2.0% from the experimental values. The results allowed us to divide the spectra of nonoxido V(IV) compounds in three types-called "type 1", "type 2", and "type 3", characterized by different composition of the singly occupied molecular orbital (SOMO) and relationship between the values of Ax, Ay, and Az. For "type 1" spectra, Az ≫ Ax ≈ Ay and Az is in the range of (135-155) × 10(-4) cm(-1); for "type 2" spectra, Ax ≈ Ay ≫ Az and Ax ≈ Ay are in the range of (90-120) × 10(-4) cm(-1); and for the intermediate spectra of "type 3", Az > Ay > Ax or Ax > Ay > Az, with Az or Ax values in the range of (120-135) × 10(-4) cm(-1). The electronic structure of the V(IV) species was also discussed, and the results showed that the values of Ax or Az are correlated with the percent contribution of V-dxy orbital in the SOMO. Similarly to V(IV)O species, for amavadin the SOMO is based mainly on the V-dxy orbital, and this accounts for the large experimental value of Az (153 × 10(-4) cm(-1)). PMID:27399275

  9. Nonoxido V(IV) Complexes: Prediction of the EPR Spectrum and Electronic Structure of Simple Coordination Compounds and Amavadin.

    Science.gov (United States)

    Sanna, Daniele; Sciortino, Giuseppe; Ugone, Valeria; Micera, Giovanni; Garribba, Eugenio

    2016-08-01

    Density functional theory (DFT) calculations of the (51)V hyperfine coupling (HFC) tensor A have been completed for 20 "bare" V(IV) complexes with different donor sets, electric charges, and coordination geometries. Calculations were performed with ORCA and Gaussian software, using functionals BP86, TPSS0, B1LYP, PBE0, B3LYP, B3P, B3PW, O3LYP, BHandHLYP, BHandH, and B2PLYP. Among the basis sets, 6-311g(d,p), 6-311++g(d,p), VTZ, cc-pVTZ, def2-TZVPP, and the "core properties" CP(PPP) were tested. The experimental Aiso and Ai (where i = x or z, depending on the geometry and electronic structure of V(IV) complex) were compared with the values calculated by DFT methods. The results indicated that, based on the mean absolute percentage deviation (MAPD), the best functional to predict Aiso or Ai is the double hybrid B2PLYP. With this functional and the basis set VTZ, it is possible to predict the Aiso and Az of the EPR spectrum of amavadin with deviations of -1.1% and -2.0% from the experimental values. The results allowed us to divide the spectra of nonoxido V(IV) compounds in three types-called "type 1", "type 2", and "type 3", characterized by different composition of the singly occupied molecular orbital (SOMO) and relationship between the values of Ax, Ay, and Az. For "type 1" spectra, Az ≫ Ax ≈ Ay and Az is in the range of (135-155) × 10(-4) cm(-1); for "type 2" spectra, Ax ≈ Ay ≫ Az and Ax ≈ Ay are in the range of (90-120) × 10(-4) cm(-1); and for the intermediate spectra of "type 3", Az > Ay > Ax or Ax > Ay > Az, with Az or Ax values in the range of (120-135) × 10(-4) cm(-1). The electronic structure of the V(IV) species was also discussed, and the results showed that the values of Ax or Az are correlated with the percent contribution of V-dxy orbital in the SOMO. Similarly to V(IV)O species, for amavadin the SOMO is based mainly on the V-dxy orbital, and this accounts for the large experimental value of Az (153 × 10(-4) cm(-1)).

  10. Coordination of complex bimanual multijoint movements under increasing cycling frequencies: the prevalence of mirror-image and translational symmetry.

    Science.gov (United States)

    Li, Yong; Levin, Oron; Forner-Cordero, Arturo; Ronsse, Renaud; Swinnen, Stephan P

    2009-03-01

    The present study examined the principles underlying inter and intralimb coordination constraints during performance of bimanual elbow-wrist movements at different cycling frequencies (from 0.75 Hz to 2.50 Hz). Participants performed eight coordination tasks that consisted of a combination of in-phase (IN) and/or anti-phase (AN) coordination modes between both elbows and wrists (interlimb), with isodirectional (Iso) or non-isodirectional (NonI) coordination modes within each limb (intralimb). As expected, the principle of muscle homology (in-phase coordination), giving rise to mirror symmetrical movements with respect to the mid-sagittal plane, had a powerful influence on the quality of global coordinative behavior both between and within limbs. When this principle was violated (i.e., when the anti-phase mode was introduced in one or both joint pairs), the non-isodirectional intralimb mode exhibited a (de)stabilizing role in coordination, which became more pronounced at higher cycling frequencies. However, pattern loss with increasing cycling frequency resulted not only in convergence toward the more stable in-phase patterns with the elbows and wrists but also to the anti-phase patterns (which were associated with directional compatibility of within-limb motions). Moreover, participants generally preserved their initial mode of coordination (either in-phase or anti-phase) in the proximal joints (i.e., elbows) while shifting from anti-phase to in-phase (or vice versa) with their distal joint pair (i.e., wrists). Taken together, these findings reflect the impact of two immanent types of symmetry in bimanual coordination: mirror-image and translational symmetry.

  11. Fac-mer equilibria of coordinated iminodiacetate (ida2-) in ternary CuII(ida)(H-1B)- complex formation (B = imidazole, benzimidazole) in aqueous solution

    Indian Academy of Sciences (India)

    Susmita Bandyopadhyay; G N Mukherjee

    2003-08-01

    pH potentiometric and spectrophotometric investigations on the complex formation equilibria of CuII with iminodiacetate (ida2-) and heterocyclic N-bases, viz. imidazole and benzimidazole (B), in aqueous solution in binary and ternary systems using different molar ratios of the reactants indicated the formation of complexes of the types, Cu(ida), Cu(ida)(OH)-, (ida)Cu(OH)Cu(ida)-, Cu(B)2+, Cu(H-1B)+, Cu(ida)(H-1B)-, (ida)Cu(B)Cu(ida) and (ida)Cu(H-1B)Cu(ida)-. Formation constants of the complexes at 25 ± 1° at a fixed ionic strength, = 0.1 mol dm-3 (NaNO3) in aqueous solution were evaluated and the complex formation equilibria were elucidated with the aid of speciation curves. Departure of the experimental values of the reproportionation constants (log Cu) of ternary Cu(ida)(H-1B)- complexes from the statistically expected values, despite their formation in appreciable amounts at equilibrium, were assigned to fac(f)-mer(m) equilibria of the ida2- ligand coordinated to CuII, as the N-heterocyclic donors, (H-1B)-, coordinate trans- to the N-(ida2-) atom in the binary Cu(ida) complex to form the ternary Cu(ida) (H-1B)- complexes.

  12. Synthesis and Crystal Structure of a Mn(Ⅱ) Complex with Thiosemicarbazone Derivative of Pyridine-3-carbaldehyde Showing Unusual Coordination Mode of Tridentate Thiosemicarbazone

    Institute of Scientific and Technical Information of China (English)

    LI Ming-Xue; ZHOU Jing; WANG Jing-Ping; WANG Zi-Liang

    2006-01-01

    The title complex Mn(HL)4(NCS)2(CH3CH2OH)2 has been achieved via selfassembly by incorporating manganese(Ⅱ) into pyridine-3-carbaldehyde thiosemicarbazonate ligand,and characterized by elemental analysis and single-crystal X-ray diffraction study. The crystal crystallizes in triclinic, space group P1 with a = 8.896(2), b = 9.530(2), c = 14.520(4) (A), α =87.035(4), β= 88.112(4), γ= 69.434(4)°, V= 1150.9(5) (A)3, Z = 1, Mr = 984.17, Dc = 1.420 g/cm3,μ(MoKα) = 0.612 mm-1, F(000) = 511, the final R = 0.0574 and wR = 0.1547 for 2855 observed reflections with I > 2σ(I). The complex contains one six-coordinated manganese ion connected by two thiosemicarbazide ligands, in which the thiosemicarbazone ligand acts as a monodentate ligand and coordinates to the center metal atoms via the pyridyl nitrogen atoms, two ethanol molecules and two isothiocyanic anions to give rise to a mononuclear structure. The coordination of a potentially tridentate thiosemicarbazone in manganese(Ⅱ) complex without using its sulfur and imine nitrogen sites is unusual. Hydrogen bonds existing in the complex link the different components to stabilize the crystal structure.

  13. Increasingly complex bimanual multi-frequency coordination patterns are equally easy to perform with on-line relative velocity feedback.

    Science.gov (United States)

    Boyles, Jason; Panzer, Stefan; Shea, Charles H

    2012-02-01

    An experiment was conducted to determine whether multi-frequency continuous bimanual circling movements of varying difficulty (1:2, 2:3, 3:4, and 4:5) could be effectively performed following relatively little practice when on-line continuous relative velocity feedback is provided. The between-subjects results indicate extremely effective bimanual multi-frequency performance for all coordination patterns with relatively stable and continuous movements of both limbs. The findings suggest that the previous performance effects using Lissajous feedback with reciprocal movement can be extended to circling movements using on-line relative velocity feedback. Contrary to the long-held position that these coordination patterns result in increasing difficulty, we failed to find systematic relative velocity error, variability, or bias differences between the participants performing the various multi-frequency coordination patterns. Indeed, coordination error, variability, and biases were remarkably low for each of the tasks. The results clearly indicate the ease with which participants are able to produce bimanual coordination patterns typically considered difficult if not impossible when salient visual information is provided that allows the participants to detect and correct their coordination errors.

  14. Extraction and coordination studies of a carbonyl-phosphine oxide scorpionate ligand with uranyl and lanthanide(III) nitrates: structural, spectroscopic and DFT characterization of the complexes.

    Science.gov (United States)

    Matveeva, Anna G; Vologzhanina, Anna V; Goryunov, Evgenii I; Aysin, Rinat R; Pasechnik, Margarita P; Matveev, Sergey V; Godovikov, Ivan A; Safiulina, Alfiya M; Brel, Valery K

    2016-03-28

    Hybrid scorpionate ligand (OPPh2)2CHCH2C(O)Me (L) was synthesized and characterized by spectroscopic methods and X-ray diffraction. The selected coordination chemistry of L with UO2(NO3)2 and Ln(NO3)3 (Ln = La, Nd, Lu) has been evaluated. The isolated mono- and binuclear complexes, namely, [UO2(NO3)2L] (1), [{UO2(NO3)L}2(μ2-O2)]·EtOH (2), [La(NO3)3L2]·2.33MeCN (3), [Nd(NO3)3L2]·3MeCN (4), [Nd(NO3)2L2]+·(NO3)−·EtOH (5) and [Lu(NO3)3L2] (6) have been characterized by IR spectroscopy and elemental analysis. Single-crystal X-ray structures have been determined for complexes 1-5. Intramolecular intraligand π-stacking interactions between two phenyl fragments of the coordinated ligand(s) were observed in all complexes 1-5. The π-stacking interaction energy was estimated from Bader's AIM theory calculations performed at the DFT level. Solution properties have been examined using IR and multinuclear ((1)H, (13)C, and (31)P) NMR spectroscopy in CD3CN and CDCl3. Coordination modes of L vary with the coordination polyhedron of the metal and solvent nature showing many coordination modes: P(O),P(O), P(O),P(O),C(O), P(O),C(O), and P(O). Preliminary extraction studies of U(VI) and Ln(III) (Ln = La, Nd, Ho, Yb) from 3.75 M HNO3 into CHCl3 show that scorpionate L extracts f-block elements (especially uranium) better than its unmodified prototype (OPPh2)2CH2.

  15. A redox-active porous coordination network film based on a Ru complex as a building block on an ITO electrode.

    Science.gov (United States)

    Shinomiya, Takuya; Ozawa, Hiroaki; Mutoh, Yuichiro; Haga, Masa-Aki

    2013-12-01

    The combination of self-assembled monolayer (SAM) and layer-by-layer (LbL) growth methods for the construction of a surface porous film has the potential to incorporate a wide range of chemical functionalities on a solid surface. A novel redox-active Ru complex with 2,6-bis(N-pyridylbenzimidazolyl)-pyridine ligands (Ru complex 1), in which four peripheral pyridine groups act as coordination sites, was used as a building block for a porous coordination network film. By using (4-pyridyl)phenylphosphonic acid as a SAM primer layer on an ITO surface, the Ru complex 1 was immobilized by the successive reaction of PdCl2 on the ITO electrode in the LbL growth method. Multilayer growth was monitored by UV-vis spectra and cyclic voltammetry, in which the linear increases of both absorbance and the peak current were observed. This result indicated that the regular accumulation of Ru complex 1 onto the ITO surface took place. The permselectivity of the present porous coordination network structure was examined using redox-active molecular probes with different sizes and charges such as ferrocene, trimethylaminomethylferrocene, the Os bis(2,6-bis(N-methylbenzimidazolyl)-pyridine) complex, and tetrathiofulvarene (TTF). With the Os complex and cationic ferrocene, only the catalytic peak was observed as a prewave of the adsorbed Ru(II/III) peak at +0.73 V. On the other hand, the oxidation peak of ferrocene was observed around 0 V vs. Fc(+)/Fc even for nine-layered films in addition to the adsorbed Ru(II/III) peak. From these results, not only molecular size but also electrostatic interaction plays an important role in the permeation into the Ru complex 1 porous network film.

  16. Coordination behavior of ligand based on NNS and NNO donors with ruthenium(III) complexes and their catalytic and DNA interaction studies

    Science.gov (United States)

    Manikandan, R.; Viswnathamurthi, P.

    2012-11-01

    Reactions of 2-acetylpyridine-thiosemicarbazone HL1, 2-acetylpyridine-4-methyl-thiosemicarbazone HL2, 2-acetylpyridine-4-phenyl-thiosemicarbazone HL3 and 2-acetylpyridine-semicarbazone HL4 with ruthenium(III) precursor complexes were studied and the products were characterized by analytical and spectral (FT-IR, electronic, EPR and EI-MS) methods. The ligands coordinated with the ruthenium(III) ion via pyridine nitrogen, azomethine nitrogen and thiolate sulfur/enolate oxygen. An octahedral geometry has been proposed for all the complexes based on the studies. All the complexes are redox active and display an irreversible and quasireversible metal centered redox processes. Further, the catalytic activity of the new complexes has been investigated for the transfer hydrogenation of ketones in the presence of isopropanol/KOH and the Kumada-Corriu coupling of aryl halides with aryl Grignard reagents. The DNA cleavage efficiency of new complexes has also been tested.

  17. Extremely bulky amido first row transition metal(II) halide complexes: potential precursors to low coordinate metal-metal bonded systems.

    Science.gov (United States)

    Hicks, Jamie; Jones, Cameron

    2013-04-01

    Reactions of the extremely bulky potassium amide complexes, [KL'(η(6)-toluene)] or [KL"] (L'/L" = N(Ar*)(SiR3), Ar* = C6H2{C(H)Ph2}2Me-2,6,4; R = Me (L') or Ph (L")), with a series of first row transition metal(II) halides have yielded 10 rare examples of monodentate amido first row transition metal(II) halide complexes, all of which were crystallographically characterized. They encompass the dimeric, square-planar chromium complexes, [{CrL'(THF)(μ-Cl)}2] and [{CrL"(μ-Cl)}2], the latter of which displays intramolecular η(2)-Ph···Cr interactions; the dimeric tetrahedral complexes, [{ML'(THF)(μ-Br)}2] (M = Mn or Fe), [{ML"(THF)(μ-X)}2] (M = Mn, Fe or Co; X = Cl or Br) and [{CoL"(μ-Cl)}2] (which displays intramolecular η(2)-Ph···Co interactions); and the monomeric zinc amides, [L'ZnBr(THF)] (three-coordinate) and [L"ZnBr] (two-coordinate). Solution state magnetic moment determinations on all but one of the paramagnetic compounds show them to be high-spin systems. Throughout, comparisons are made with related bulky terphenyl transition metal(II) halide complexes, and the potential for the use of the prepared complexes as precursors to low-valent transition metal systems is discussed.

  18. Synthesis, spectroscopic studies, thermal analyses, biological activity of tridentate coordinated transition metal complexes of bi(pyridyl-2-ylmethyl)amine]ligand

    Science.gov (United States)

    Abd El-Halim, Hanan F.; Mohamed, Gehad G.

    2016-01-01

    A new tridentate acyclic pincer ligand, [bi(pyridin-2-methyl)amine] (bpma, HL), was synthesized and reacted to form complexes with copper(II), nickel(II), iron(II), cobalt(II) and zinc(II) ions. Both the ligand and its complexes were characterized using elemental analysis, molar conductance, infrared, 1H-NMR-spectroscopy, mass and thermal analyses. According to the spectroscopic data, all of the complexes share the same coordination environment around the metal atoms, consisting two nitrogen-pyridine entities, one nitrogen-methylamine entity, one/two water molecules and/or one/two chloride or bromide ions. Complexes also showed molar conductivity according to the presence of two halide anions outer the coordination sphere except Co(II) and Zn(II) complexes are non electrolytes. Analysis indicates that the metal ions have trigonal bipyramidal structure. Cu(II), Ni(II), Fe(II), Co(II), and Zn(II) metal complexes were screened for their antibacterial activity against Bacillus subtilis, Staphylococcus aureus (G+) and Escherichia coli, and Pseudomonas aeruginosa (G-) bacteria. They showed remarkable antimicrobial activity.

  19. Variation of the coordination environment and its effect on the white light emission properties in a Mn-doped ZnO-ZnS complex structure.

    Science.gov (United States)

    Cheng, Yan; Chen, Rui; Feng, Haifeng; Hao, Weichang; Xu, Huaizhe; Wang, Yu; Li, Jiong

    2014-03-14

    Mn-doped ZnO-ZnS complex nanocrystals were fabricated through coating of dodecanethiol on Mn-doped ZnO nanocrystals. The relationship between the component of white light emission and the coordination environments of Mn-dopants were experimentally investigated. It was shown that Mn ions mainly formed Mn(3+)O6 octahedra in as prepared Mn-doped ZnO, while the Mn(3+) ions on the surface of ZnO transferred into Mn(2+) ions at the interface between ZnO and ZnS after dodecanethiol coating. The Mn(2+)S4 tetrahedron density and the orange emission intensity increased upon enhancing the dodecanethiol content. These results provide an alternative way to optimize the white emission spectrum from nanocrystals of Mn-doped ZnS-ZnO complex structures through modulation of the coordination environment of Mn ions.

  20. Synthesis and crystal structures of two coordination polymers and a binuclear cadmium(II) complex containing 3- and 4-aminobenzoate ligands.

    Science.gov (United States)

    Zhou, Dong-Mei; Zhao, Xiao-Lan; Liu, Feng-Yi; Kou, Jun-Feng

    2015-08-01

    Due to their wide range of coordination modes and versatile conformations when binding to metal atoms, multicarboxylate ligands are of interest in the design of metal-organic frameworks (MOFs). Three Cd(II) complexes, namely catena-poly[diammonium [[chloridocadmium(II)]-di-μ-chlorido-[chloridocadmium(II)]-bis(μ-3-aminobenzoato)-κ(3)N:O,O';κ(3)O,O':N

  1. Rate enhancement of the catechol oxidase activity of a series of biomimetic monocopper(II) complexes by introduction of non-coordinating groups in N-tripodal ligands

    OpenAIRE

    Marion, Ronan; Saleh, Nidal; Le Poul, Nicolas; Floner, Didier; Lavastre, Olivier; Geneste, Florence

    2012-01-01

    International audience Asymmetrical N-tripodal ligands have been synthesized in three steps. Diversity has been introduced at the first step of the synthesis by adding pyrazine, pyridine, benzyl and thiophene rings. The corresponding CuII complexes have been prepared by reaction with CuCl2 and characterized by Electron Paramagnetic Resonance (EPR), UV-Vis spectroscopies and cyclic voltammetry. The data show that the ligand coordinates to CuII in a mononuclear fashion in solution and that t...

  2. Seven-coordinate anion complex with a tren-based urea: Binding discrepancy of hydrogen sulfate in solid and solution states

    Energy Technology Data Exchange (ETDEWEB)

    Pramanik, Avijit [Jackson State University; Thompson, Bethtrice [Jackson State University; Hayes, Trina [Jackson State University; Tucker, Kimberly [Jackson State University; Powell, Douglas R. [University of Oklahoma, Norman; Bonnesen, Peter V [ORNL; Ellis, Erick D [Jackson State University; Lee, Ken S. [Jackson State University; Yu, Hongtau [Jackson State University; Hossain, Md. Alamgir [Jackson State University

    2011-01-01

    Structural characterization of a hydrogen sulfate complex with a tren-based urea suggests that the anion is coordinated with sixNH Obonds (dN O = 2.857 (3) to 3.092 (3)A ) and one OH O bond (dO O = 2.57 (2) A ) from three receptors; however, in solution the anion is bound within the pseudocavity of one receptor.

  3. Non-oxo 5-coordinate and 6-coordinate vanadium(IV) complexes with their precursor [LV(III)(CH3OH)](0), where L = a trianionic aminetris(phenolate)-[N,O,O,O] donor ligand: a magnetostructural and EPR study.

    Science.gov (United States)

    Kajiwara, Takashi; Wagner, Rita; Bill, Eckhard; Weyhermüller, Thomas; Chaudhuri, Phalguni

    2011-12-21

    Ligating properties of a tripodal, potentially tetradentate aminetris(phenol) ligand, tris(2-hydroxy-3,5-di-tert-butylbenzyl)amine, H(3)L, containing [N,O,O,O] donor atoms toward the vanadium ions in +III and IV oxidation states have been studied. The structures of complexes 1 [LV(III)(CH(3)OH)](0), 2 [LV(IV)(OCH(3))](0) and 3 [LV(IV)(acac)](0) were determined by X-ray diffraction methods as having five-coordinate V(III), 1, five-coordinate non-oxo-vanadium(IV), 2, and six-coordinate non-oxo-vanadium(iv) 3, respectively. Compounds 1-3 were also studied with electrochemical methods, variable-temperature (2-295 K) magnetic susceptibility measurements and X-band electron paramagnetic resonance (EPR) spectroscopy. The electrochemical results of 2 and 3 suggest metal-centered oxidation, i.e. the generation of a V(V)-phenolate species. EPR investigations indicate a (d(xy))(1) ground state showing a considerable increase in the in-plane π-bonding, as is expected for a phenolate ligand. PMID:22005800

  4. Novel Ni(II) and Zn(II) complexes coordinated by 2-arylaminomethyl-1H-benzimidazole: Molecular structures, spectral, DFT studies and evaluation of biological activity

    Science.gov (United States)

    Abdel-Ghani, Nour T.; Abo El-Ghar, Maha F.; Mansour, Ahmed M.

    2013-03-01

    [NiL1,2Cl2(OH2)3]·zH2O and [ZnL1,2(CH3CO2)2] (L1 = (1H-benzimidazol-2-ylmethyl)-N-phenyl amine, z = 0 and L2 = 2-[(1H-Benzimidazol-2-ylmethyl)-amino]-benzoic acid methyl ester, z = 1) complexes have been synthesized and characterized by a variety of physico-chemical techniques. The central Ni(II) ion is coordinated by only the pyridine-type nitrogen (Npy) of benzimidazole ring, three water molecules and two chlorido ligands forming a distorted octahedral geometry. Five coordinated zinc complexes were obtained, where the coordination sphere of zinc ion is made up of secondary amino group (NHsec), Npy and two acetate groups, one acts as a unidentate and the other as a bidentate. A theoretical DFT/UB3LYP method combined with LANL2DZ basis set shows that all the metal-ligand bonds are of the L → M type. Electronic structures have been calculated using TD-DFT method. The antibacterial activity of NiL2 complexes decreases by the introduction of COOCH3 group in the ortho-position of the aniline moiety.

  5. Synthesis and structural investigations of some five-coordinated oxovanadium(IV) complexes of 4[N-(benzylidene)amino] antipyrine semicarbazone

    International Nuclear Information System (INIS)

    The synthesis and spectral characteristics of a new series of five coordinated oxovanadium(IV) complexes of 4[N-(benzylidene) antipyrine semicarbazone (BAAPS) with general composition VOX2.BAAPS (X=Cl, Br, I, No3 or NCS) and VO(ClO4)2. BAAPS.H2O are reported together with molecular conductivity, molecular weights, magnetic susceptibility, infrared and electronic spectra. In all the complexes, the BAAPS behaves as neutral tridentate (N,N,O) ligand. (author). 12 refs., 3 tabs

  6. Bulky N-Phosphino-Functionalized N-Heterocyclic Carbene Ligands: Synthesis, Ruthenium Coordination Chemistry, and Ruthenium Alkylidene Complexes for Olefin Metathesis.

    Science.gov (United States)

    Brown, Christopher C; Rominger, Frank; Limbach, Michael; Hofmann, Peter

    2015-11-01

    Ruthenium chemistry and applications in catalytic olefin metathesis based on N-phosphino-functionalized N-heterocyclic carbene ligands (NHCPs) are presented. Alkyl NHCP Ru coordination chemistry is described, and access to several potential synthetic precursors for ruthenium alkylidene complexes is outlined, incorporating both trimethylsilyl and phenyl alkylidenes. The Ru alkylidene complexes are evaluated as potential olefin metathesis catalysts and were shown to behave in a latent fashion. They displayed catalytic activity at elevated temperatures for both ring closing metathesis and ring opening metathesis polymerization. PMID:26479425

  7. Coordination Chemistry of Polyaromatic Thiosemicarbazones 2: Synthesis and Biological Activity of Zinc, Cobalt, and Copper Complexes of 1-(Naphthalene-2-yl)ethanone Thiosemicarbazone

    OpenAIRE

    Marc-Andre LeBlanc; Antonio Gonzalez-Sarrías; Beckford, Floyd A.; P. Canisius Mbarushimana; Seeram, Navindra P.

    2011-01-01

    A novel thiosemicarbazone from 2-acetonaphthone (represented as acnTSC) has been synthesized and its basic coordination chemistry with zinc(II), cobalt(II), and copper(II) explored. The complexes were characterized by elemental analysis and various spectroscopic techniques and are best formulated as [M(acnTSC)2Cl2] with the metal likely in an octahedral environment. The anticancer activity of the complexes was determined against a panel of human colon cancer cells (HCT-116 and Caco-2). The co...

  8. Bulky N-Phosphino-Functionalized N-Heterocyclic Carbene Ligands: Synthesis, Ruthenium Coordination Chemistry, and Ruthenium Alkylidene Complexes for Olefin Metathesis.

    Science.gov (United States)

    Brown, Christopher C; Rominger, Frank; Limbach, Michael; Hofmann, Peter

    2015-11-01

    Ruthenium chemistry and applications in catalytic olefin metathesis based on N-phosphino-functionalized N-heterocyclic carbene ligands (NHCPs) are presented. Alkyl NHCP Ru coordination chemistry is described, and access to several potential synthetic precursors for ruthenium alkylidene complexes is outlined, incorporating both trimethylsilyl and phenyl alkylidenes. The Ru alkylidene complexes are evaluated as potential olefin metathesis catalysts and were shown to behave in a latent fashion. They displayed catalytic activity at elevated temperatures for both ring closing metathesis and ring opening metathesis polymerization.

  9. MnBr2/18-crown-6 coordination complexes showing high room temperature luminescence and quantum yield.

    Science.gov (United States)

    Hausmann, David; Kuzmanoski, Ana; Feldmann, Claus

    2016-04-12

    The reaction of manganese(ii) bromide and the crown ether 18-crown-6 in the ionic liquid [(n-Bu)3MeN][N(Tf)2] under mild conditions (80-130 °C) resulted in the formation of three different coordination compounds: MnBr2(18-crown-6) (), Mn3Br6(18-crown-6)2 () and Mn3Br6(18-crown-6) (). In general, the local coordination and the crystal structure of all compounds are driven by the mismatch between the small radius of the Mn(2+) cation (83 pm) and the ring opening of 18-crown-6 as a chelating ligand (about 300 pm). This improper situation leads to different types of coordination and bonding. MnBr2(18-crown-6) represents a molecular compound with Mn(2+) coordinated by two bromine atoms and only five oxygen atoms of 18-crown-6. Mn3Br6(18-crown-6)2 falls into a [MnBr(18-crown-6)](+) cation - with Mn(2+) coordinated by six oxygen atoms and Br - and a [MnBr(18-crown-6)MnBr4](-) anion. In this anion, Mn(2+) is coordinated by five oxygen atoms of the crown ether as well as by two bromine atoms, one of them bridging to an isolated (MnBr4) tetrahedron. Mn3Br6(18-crown-6), finally, forms an infinite, non-charged [Mn2(18-crown-6)(MnBr6)] chain. Herein, 18-crown-6 is exocyclically coordinated by two Mn(2+) cations. All compounds show intense luminescence in the yellow to red spectral range and exhibit remarkable quantum yields of 70% (Mn3Br6(18-crown-6)) and 98% (Mn3Br6(18-crown-6)2). The excellent quantum yield of Mn3Br6(18-crown-6)2 and its differentiation from MnBr2(18-crown-6) and Mn3Br6(18-crown-6) can be directly correlated to the local coordination. PMID:26956783

  10. Experimental study on transition metal complexes containing N,S-, S,S- and O,O- coordinated π radicals

    OpenAIRE

    Kapre, Ruta R.

    2005-01-01

    The coordination chemistry of transition metals with bidentate ligands derived from o-aminothiophenolate, o-dithiolate and o-catacholate has been studied in this work. The ligands used were: 1) o-aminothiophenol [LNS] 2) 2- Phenylbenzothiazoline [LPH] 3) 2-mercapto-3,5-di-tert-butylaniline H2[tLNS] 4) 3,5-di-tert-butyl-1,2-benzenedithiol H2 [tLSS] 5) 3,6-di-tert-butylcatacholate H2[tLCat]. These ligands were readily one-electron oxidized yielding N,S-, S,S- and O,O-coordinated π r...

  11. Studies on coordination chemistry and bioactivity of metal complexes of some nitrogen-sulfur donor ligands: Section A: hydraziniumdithiocarbazate and its complexes. Section B: complexes of Ni2+ and Cu2+ ions with s-picolyldithiocarbazate

    International Nuclear Information System (INIS)

    Two new nitrogen - sulphur donor ligands, hydraziniumdithiocarbazate(HzDTC) and S-picolyldithiocarbazate(SPDTC), along with three novel Schiff bases were prepared. Complexes of some of HzDTC with nickel(II), zinc(II), and those of SPDTC with nickel(II) and copper(II) were prepared and characterized by a variety of physico- chemical techniques. The ligand, HzDTC, was a potential bidentate and uninegatively charged providing terminal amino and thiolate bindings with the metal ions, while SPDTC coordinates via the pyridine nitrogen and the thiolate anion. All of the compounds were tested against four pathogenic bacteria and fungi. HzDTC was found to be very effective antimicrobial than its complexes. The complexes of SPDTC and the Schiff bases of HzDTC were more antifungal. None of the compounds were effective anti- cancer agents except for [Ni(HzDTCA)Cl.H2O], which was moderately active against CEM- SS (Human cell T- lymphoblastic) leukemic cells. (author)

  12. Coordination behavior of N-benzoylamino acids: Synthesis and structure of mixed-ligand complexes of palladium(Ⅱ) with N-benzoylamino acid dianion and diamine

    Institute of Scientific and Technical Information of China (English)

    龚钰秋; 陈耀峰; 顾建明; 胡秀荣

    1997-01-01

    Four new mixed-ligand complexes of pailadiumt(Ⅱ) with L1(N-benzoyl-α-amino acid dianion) and L2[ethyldiamine (en),2,2’-bipyridine (Bpy) and 1,10-phenanthroline (Phen)] were synthesized.Ail the complexes have been characterized by elemental analyses,molar conductance,infrared and 1H NMR spectra and therme-gravimetric analyses.Crystal structures of [Pd(Bpy)(Bzval-N,O)] and [Pd(en) (Bzphe-N,O)] H2O have been do termmed by X-ray diffraction analysis.The results indicate that in all the complexes hgand L1 coordinates to palladium (Ⅱ) through deprotonated amide nitrogen and carboxylic oxygen,and there are some intramolecular nonrovalent in teractions in the complexes.

  13. Genetic effects of some platinum co-ordination complexes on E.coli DNA as revealed by transformation studies

    NARCIS (Netherlands)

    Hoekstra, W.P.M.; Daemen, Toos

    1982-01-01

    E. coli chromosomal DNA was treated with various Pt co-ordination compounds and then used as donor DNA in E. coli transformation. Genetic analysis of transformants obtained with Pt-treated DNA showed effects of cis-diamminedichloroplatinum(II) (cis-Pt(II)) and cis-Pt-dimethyl-1,3-diaminopropane Cl4

  14. Synthesis, Coordination Chemistry, and Cooperative Activation of H2 with Ruthenium Complexes of ProtonResponsive METAMORPhos Ligands

    NARCIS (Netherlands)

    F.G. Terrade; M. Lutz; J.I. van der Vlugt; J.N.H. Reek

    2014-01-01

    The synthetic scope of proton-responsive sulfonamidophosphorus (METAMORPhos) ligands is expanded and design principles for the selective formation of particular tautomers, ion pairs, or double condensation products are elucidated. These systems have been introduced in the coordination sphere of Ru f

  15. Synthesis, coordination chemistry, and cooperative activation of H 2 with ruthenium complexes of proton-responsive METAMORPhos ligands

    NARCIS (Netherlands)

    Terrade, Frédéric G.; Lutz, Martin; Van Der Vlugt, Jarl Ivar; Reek, Joost N H

    2014-01-01

    The synthetic scope of proton-responsive sulfonamidophosphorus (METAMORPhos) ligands is expanded and design principles for the selective formation of particular tautomers, ion pairs, or double condensation products are elucidated. These systems have been introduced in the coordination sphere of Ru f

  16. VARIABILITY OF COORDINATION COMPLEXES OF COPPER ACCUMULATED WITHIN FUNGAL COLONY IN THE PRESENCE OF COPPER-CONTAINING MINERALS

    Directory of Open Access Journals (Sweden)

    M. O. Fomina

    2014-04-01

    Full Text Available The aim of work was to elucidate the mechanisms of bioaccumulation of copper leached from minerals by fungus Aspergillus niger with great bioremedial potential due to its ability to produce chelating metabolites and transform toxic metals and minerals. The special attention was paid to the chemical speciation of copper bioaccumulated within fungal colony in the process of fungal transformation of copper-containing minerals. Chemical speciation of copper within different parts of the fungal colony was studied using solid-state chemistry methods such as synchrotron-based X-ray absorption spectroscopy providing information about the oxidation state of the target element, and its coordination environment. The analysis of the obtained X-ray absorption spectroscopy spectra was carried out using Fourier transforms of Extended X-ray Absorption Fine Structure regions, which correspond to the oscillating part of the spectrum to the right of the absorption edge. Results of this study showed that fungus A. niger was involved in the process of solubilization of copper-containing minerals resulted in leaching of mobile copper and its further immobilization by fungal biomass with variable coordination of accumulated copper within fungal colony which depended on the age and physiological/reproductive state of fungal mycelium. X-ray absorption spectroscopy data demonstrated that copper accumulated within outer zone of fungal colony with immature vegetative mycelium was coordinated with sulphur–containing ligands, in contrast to copper coordination with phosphate ligands within mature mycelium with profuse conidia in the central zone of the colony. The findings of this study not only broaden our understanding of the biogeochemical role of fungi but can also be used in the development of various fungal-based biometallurgy technologies such as bioremediation, bioaccumulation and bioleaching and in the assessment of their reliability. The main conclusion is that

  17. Nickel(II) complexes having Imidazol-2-ylidene-N′-phenylurea ligand in the coordination sphere – syntheses and solid state structures

    Indian Academy of Sciences (India)

    Kishor Naktode; Abhinanda Kundu; Sudeshna Saha; Hari Pada Nayek; Tarun K Panda

    2015-08-01

    We report the syntheses and structural studies of two nickel(II) complexes of imidazol-2-ylidene- N'-phenylureate ligand of composition [{ImBu NCON(H)Ph}2 Ni(acac)2] (1) and [(C6H5NH2)2 Ni(acac)2] [ImMes NCON(H)Ph] (2). The nickel complex 1 was readily prepared by the reaction of nickel(II) acetylacetonate [Ni(acac) 2 ] with imidazol-2-ylidene-N'-phenylureate ligand [ImBu NCON(H)Ph] (L1) in THF under reflux condition for 72 h. The nickel complex 2 was obtained by the reaction of [Ni(acac)2], mesityl derivative of imidazol-2-ylidene-N′-phenylureate ligand [ImMes NCON(H)Ph] (L2) in the presence of aniline as base under reflux condition in THF. Both the paramagnetic complexes have been characterized by FT-IR spectroscopy and elemental analyses. Solid-state structures of both the new complexes were established by single crystal X-ray diffraction analysis. In the molecular structures of complexes 1 and 2, each nickel(II) ion is six fold coordinated and form a distorted octahedral geometry. The optical properties of both complexes have been explored. The Hirshfeld surfaces are used to view and analyze the intermolecular contacts in crystalline state for complex 2.

  18. Robust Crosslinked Stereocomplexes and C60 Inclusion Complexes of Vinyl-Functionalized Stereoregular Polymers Derived from Chemo/Stereoselective Coordination Polymerization

    KAUST Repository

    Vidal, Fernando

    2016-07-07

    The successful synthesis of highly syndiotactic polar vinyl polymers bearing the reactive pendant vinyl group on each repeat unit, which is enabled by perfectly chemoselective and highly syndiospecific coordination polymerization of divinyl polar monomers developed through this work, has allowed the construction of robust crosslinked supramolecular stereocomplexes and C60 inclusion complexes. The metal-mediated coordination polymerization of three representative polar divinyl monomers, including vinyl methacrylate (VMA), allyl methacrylate (AMA), and N,N-diallyl acrylamide (DAA) by Cs-ligated zirconocenium ester enolate catalysts under ambient conditions exhibits complete chemoselectivity and high stereoselectivity, thus producing the corresponding vinyl-functionalized polymers with high (92% rr) to quantitative (>99% rr) syndiotacticity. A combined experimental (synthetic, kinetic, and mechanistic) and theoretical (DFT) investigation has yielded a unimetallic, enantiomorphic-site controlled propagation mechanism. Post-functionalization of the obtained syndiotactic vinyl-functionalized polymers via the thiol-ene click and photocuring reactions readily produced the corresponding thiolated polymers and flexible crosslinked thin film materials, respectively. Complexation of such syndiotactic vinyl-functionalized polymers with isotactic poly(methyl methacrylate) and fullerene C60 generates supramolecular crystalline helical stereocomplexes and inclusion complexes, respectively. Crosslinking of such complexes afforded robust crosslinked stereocomplexes that are solvent resistant and also exhibit considerably enhanced thermal and mechanical properties as compared to the uncrosslinked stereocompexes.

  19. Robust Cross-Linked Stereocomplexes and C60 Inclusion Complexes of Vinyl-Functionalized Stereoregular Polymers Derived from Chemo/Stereoselective Coordination Polymerization.

    Science.gov (United States)

    Vidal, Fernando; Falivene, Laura; Caporaso, Lucia; Cavallo, Luigi; Chen, Eugene Y-X

    2016-08-01

    The successful synthesis of highly syndiotactic polar vinyl polymers bearing the reactive pendant vinyl group on each repeat unit, which is enabled by perfectly chemoselective and highly syndiospecific coordination polymerization of divinyl polar monomers developed through this work, has allowed the construction of robust cross-linked supramolecular stereocomplexes and C60 inclusion complexes. The metal-mediated coordination polymerization of three representative polar divinyl monomers, including vinyl methacrylate (VMA), allyl methacrylate (AMA), and N,N-diallyl acrylamide (DAA) by Cs-ligated zirconocenium ester enolate catalysts under ambient conditions exhibits complete chemoselectivity and high stereoselectivity, thus producing the corresponding vinyl-functionalized polymers with high (92% rr) to quantitative (>99% rr) syndiotacticity. A combined experimental (synthetic, kinetic, and mechanistic) and theoretical (DFT) investigation has yielded a unimetallic, enantiomorphic-site-controlled propagation mechanism. Postfunctionalization of the obtained syndiotactic vinyl-functionalized polymers via the thiol-ene click and photocuring reactions readily produced the corresponding thiolated polymers and flexible cross-linked thin-film materials, respectively. Complexation of such syndiotactic vinyl-functionalized polymers with isotactic poly(methyl methacrylate) and fullerene C60 generates supramolecular crystalline helical stereocomplexes and inclusion complexes, respectively. Cross-linking of such complexes affords robust cross-linked stereocomplexes that are solvent-resistant and also exhibit considerably enhanced thermal and mechanical properties compared with the un-cross-linked stereocomplexes. PMID:27388024

  20. Exploring the coordinative adaptation and molecular shapes of trinuclear CuM(II) (M = Zn/Cd) complexes derived from salen type Schiff bases: structural and theoretical studies.

    Science.gov (United States)

    Hazari, Alokesh; Das, Lakshmi Kanta; Bauzá, Antonio; Frontera, Antonio; Ghosh, Ashutosh

    2016-04-01

    Three new trinuclear hetero-metallic complexes [(CuL)2Zn(NCS)2] (1), [(CuL(R))2Zn(NCS)(μ1,1-NCS)] (2) and [(CuL(R))2Cd(μ1,3-NCS)2] (4) have been synthesized using [CuL] and [CuL(R)] as "metalloligands" (where H2L = N,N'-bis(salicylidene)-1,3-propanediamine and H2L(R) = N,N'-bis(2-hydroxybenzyl)-1,3-propanediamine). All three complexes are characterized by elemental analysis, spectroscopic methods and single crystal XRD. Complex 1 is an angular trinuclear species, in which two terminal four-coordinate square planar "metalloligands" [CuL] are coordinated to a central Zn(ii) through double phenoxido bridges along with two mutually cis nitrogen atoms of terminal isothiocyanate ions as is usually found in such complexes. In contrast, in complex 2, the two terminal "metalloligands" [CuL(R)] are square pyramidal, as one of the SCN(-) ions makes an unusual μ1,1-NCS bridge between copper centers while the other one coordinates to Zn(ii) through a N atom in a usual fashion making its geometry also square pyramidal. For 4 which possesses an angular trinuclear structure, in addition to double phenoxido bridges from two terminal [CuL(R)], both the SCN(-) ions are S-bonded to Cd(ii) and form a bridge (cis-μ1,3-SCN) between Cd(ii) and each of the terminal Cu(ii) ions. This structure is different from its unreduced analogue in which NCS(-) was N-terminal coordinated to Cd(ii) (3/3'). All the structures have been optimized using density functional theory (DFT) calculations. It has been found that for H2L, optimized structures like 1 and 2 differ only by 0.4 kcal mol(-1) but the H2L(R) structure 2 is more stable by 5.5 kcal mol(-1) than the structure resembling 1. For Cd(ii) complexes also, H2L optimized structures such as 3 and 4 do not differ significantly in energy (1.0 kcal mol(-1)) but the H2L(R) structure 4 is more stable than that of 3 by 4.6 kcal mol(-1). In fact, structure 4 has been found to be the most stable one among the other possible isomers of H2L(R). PMID

  1. Mixed-valence copper(I,II) complexes with 4-(1H-pyrazol-1-yl)-6-R-pyrimidines: from ionic structures to coordination polymers.

    Science.gov (United States)

    Vinogradova, Katerina A; Krivopalov, Viktor P; Nikolaenkova, Elena B; Pervukhina, Natalia V; Naumov, Dmitrii Yu; Boguslavsky, Evgenii G; Bushuev, Mark B

    2016-01-14

    Two pyrimidine-based ligands, 4-(3,5-diphenyl-1H-pyrazol-1-yl)-6-(morpholino)pyrimidine () and 4-(3,5-diphenyl-1H-pyrazol-1-yl)-6-phenoxypyrimidine (), and a series of mixed-valence copper(i,ii) halide complexes, [Cu(L(2))2Br]2[Cu2Br4] (), [Cu(L(2))2Cl][CuCl2] (), and [Cu2L(3)Br3]n (), have been synthesized. The complex [Cu(L(2))2Br]2[Cu2Br4] was prepared by the reaction of with CuBr2 in a 1 : 1 molar ratio in MeCN. Its chlorido-analogue, the complex [Cu(L(2))2Cl][CuCl2], was synthesized by the reaction between , CuCl2 and CuCl in a 2 : 1 : 1 molar ratio in MeCN. The ligand acts as a chelating one. In the structures of the complexes [Cu(L(2))2Br]2[Cu2Br4] and [Cu(L(2))2Cl][CuCl2] the Cu(2+) ion is in the cationic part of the complex whereas the Cu(+) ion is located in the anionic part. The best way to synthesize the mixed-valence 1D coordination polymer [Cu2L(3)Br3]n is to react CuBr2 with in a 2 : 1 molar ratio in the MeCN/CHCl3 mixture on heating. In the structure of [Cu2L(3)Br3]n the ligand shows chelating/bridging tridentate coordination. This is the first example of the tridentate coordination of 4-(1H-pyrazol-1-yl)-6-R-pyrimidines. The striking difference between the coordination behavior of and (chelating bidentate vs. chelating/bridging coordination) is related with the possibility of rotation of the 6-phenoxy group around the C-O bond which makes the N(1) pyrimidine atom less sterically hindered, enabling it to participate in metal ion binding. Importantly, all copper ions in [Cu2L(3)Br3]n show similar tetrahedral environments, CuNBr3 and CuN2Br2, which is extremely rare for mixed-valence copper(i,ii) compounds. The ligands and show blue emission which is quenched upon their coordination to copper ions. The 1D coordination polymer [Cu2L(3)Br3]n shows high thermal stability and unusual solvent-occlusion properties. The role of the substituents favoring the formation of the mixed-valence copper(i,ii) complexes with 4-(1H-pyrazol-1-yl)-6-R

  2. Synthesis and investigation of new heteronuclear [Zn-La] coordination compounds based on unsaturated lanthanum complex with N,N'-tetraethyl-N''-trichloacetylphosphortriamide

    International Nuclear Information System (INIS)

    New heteronuclear [Zn-La] coordination compounds, perspective luminescent materials, with general formulas [Zn(Ve)La(X)2(Ac)] ({Zn-La;Ve;X}) and [Zn(Vp)La(X)2(Ac)] ({Zn-La;Vp;X}) have been synthesized HX=CCl3C(O)NHP(O)[N(C2H5)2]2 - N,N'-tetraethyl-N''-trichloracetylphosphortriamide, H2Ve and H2Vp are products of the condensation of 1,2-diaminoethane and 1,3-diaminopropane with o-vanillin, respectively). The composition of [Zn-La] complexes has been determined, and the coordination mode of a phosphorylated ligand has been suggested by element analysis, IR- and 1H, 31P NMR-spectroscopy.

  3. Coordination Chemistry of Polyaromatic Thiosemicarbazones 2: Synthesis and Biological Activity of Zinc, Cobalt, and Copper Complexes of 1-(Naphthalene-2-yl)ethanone Thiosemicarbazone

    Science.gov (United States)

    LeBlanc, Marc-Andre; Gonzalez-Sarrías, Antonio; Beckford, Floyd A.; Mbarushimana, P. Canisius; Seeram, Navindra P.

    2012-01-01

    A novel thiosemicarbazone from 2-acetonaphthone (represented as acnTSC) has been synthesized and its basic coordination chemistry with zinc(II), cobalt(II), and copper(II) explored. The complexes were characterized by elemental analysis and various spectroscopic techniques and are best formulated as [M(acnTSC)2Cl2] with the metal likely in an octahedral environment. The anticancer activity of the complexes was determined against a panel of human colon cancer cells (HCT-116 and Caco-2). The compounds bind to DNA via an intercalative mode with binding constants of 9.7 × 104 M−1, 1.8 × 105 M−1, and 9.5 × 104 M−1 for the zinc, cobalt, and copper complexes, respectively. PMID:22303515

  4. Coordination Chemistry of Polyaromatic Thiosemicarbazones 2: Synthesis and Biological Activity of Zinc, Cobalt, and Copper Complexes of 1-(Naphthalene-2-ylethanone Thiosemicarbazone

    Directory of Open Access Journals (Sweden)

    Marc-Andre LeBlanc

    2011-01-01

    Full Text Available A novel thiosemicarbazone from 2-acetonaphthone (represented as acnTSC has been synthesized and its basic coordination chemistry with zinc(II, cobalt(II, and copper(II explored. The complexes were characterized by elemental analysis and various spectroscopic techniques and are best formulated as [M(acnTSC2Cl2] with the metal likely in an octahedral environment. The anticancer activity of the complexes was determined against a panel of human colon cancer cells (HCT-116 and Caco-2. The compounds bind to DNA via an intercalative mode with binding constants of 9.7×104 M-1, 1.8×105 M-1, and 9.5×104 M-1 for the zinc, cobalt, and copper complexes, respectively.

  5. Spectroscopic properties and electronic structure of five- and six-coordinate iron(II) porphyrin NO complexes: Effect of the axial N-donor ligand.

    Science.gov (United States)

    Praneeth, V K K; Näther, Christian; Peters, Gerhard; Lehnert, Nicolai

    2006-04-01

    In this paper, the differences in the spectroscopic properties and electronic structures of five- and six-coordinate iron(II) porphyrin NO complexes are explored using [Fe(TPP)(NO)] (1; TPP = tetraphenylporphyrin) and [Fe(TPP)(MI)(NO)] (2; MI = 1-methylimidazole) type systems. Binding of N-donor ligands in axial position trans to NO to five-coordinate complexes of type 1 is investigated using UV-vis absorption and 1H NMR spectroscopies. This way, the corresponding binding constants Keq are determined and the 1H NMR spectra of 1 and 2 are assigned for the first time. In addition, 1H NMR allows for the determination of the degree of denitrosylation in solutions of 1 with excess base. The influence of the axial ligand on the properties of the coordinated NO is then investigated. Vibrational spectra (IR and Raman) of 1 and 2 are presented and assigned using isotope substitution and normal-coordinate analysis. Obtained force constants are 12.53 (N-O) and 2.98 mdyn/A (Fe-NO) for 1 compared to 11.55 (N-O) and 2.55 mdyn/A (Fe-NO) for 2. Together with the NMR results, this provides experimental evidence that binding of the trans ligand weakens the Fe-NO bond. The principal bonding schemes of 1 and 2 are very similar. In both cases, the Fe-N-O subunit is strongly bent. Donation from the singly occupied pi* orbital of NO into d(z2) of iron(II) leads to the formation of an Fe-NO sigma bond. In addition, a medium-strong pi back-bond is present in these complexes. The most important difference in the electronic structures of 1 and 2 occurs for the Fe-NO sigma bond, which is distinctively stronger for 1 in agreement with the experimental force constants. The increased sigma donation from NO in 1 also leads to a significant transfer of spin density from NO to iron, as has been shown by magnetic circular dichroism (MCD) spectroscopy in a preceding Communication (Praneeth, V. K. K.; Neese, F.; Lehnert, N. Inorg. Chem. 2005, 44, 2570-2572). This is confirmed by the 1H NMR results

  6. Synthesis of monomeric and polymeric alkali and alkaline earth metal complexes using a phosphinoselenoic amide ligand in metal coordination sphere

    Indian Academy of Sciences (India)

    Jayeeta Bhattacharjee; Ravi K Kottalanka; Harinath Adimulam; Tarun K Panda

    2014-09-01

    We report the monomeric complexes of magnesium and calcium of composition [M(THF){2-Ph2P(Se)N(CMe3)}2] [M= Mg (3), n = 1 andM = Ca (4), n = 2)] and polymeric complexes of potassium and barium of composition [K(THF)2{Ph2P(Se)N(CMe3)}] (2) and [K(THF)Ba{Ph2P(Se)N(CMe3)}3](5) respectively. The potassium complex 2 was readily prepared by the reaction of potassium bis(trimethylsilyl)amide with phosphinoselenoic amide ligand (1) at ambient temperature. The calcium complex 4 was prepared by two synthetic routes: in the first method, commonly known as salt metathesis reaction, the potassium complex 2 was made to react with alkaline earth metal diiodide at room temperature to afford the corresponding calcium complex. The metal bis(trimethylsilyl)amides were made to react with protic ligand 1 in the second method to eliminate the volatile bis(trimethyl)silyl amine. The magnesium complex 3 and barium complex 5 were prepared only through the first method. Solid-state structures of all the new complexes were established by single crystal X-ray diffraction analysis. The smaller ionic radii of Mg2+ (0.72Å) and Ca2+ (0.99Å) ions form the monomeric complex, whereas the larger ions K+ (1.38Å) and Ba2+ (1.35Å) were found to form onedimensional polymeric complexes with monoanionic ligand 1. Compound 2 serves an example of magnesium complex with a Mg-Se direct bond.

  7. Zirconium and hafnium complexes containing N-alkyl substituted amine biphenolate ligands: coordination chemistry and living ring-opening polymerization catalysis.

    Science.gov (United States)

    Liang, Lan-Chang; Lin, Sheng-Ta; Chien, Chia-Cheng; Chen, Ming-Tsz

    2013-07-01

    The coordination chemistry of zirconium and hafnium complexes containing the tridentate amine biphenolate ligands [RN(CH2-2-O-3,5-C6H2(tBu)2)2](2-) ([R-ONO](2-); R = tBu (1a), iPr (1b), nPr (1c)) featuring distinct N-alkyl substituents is described. Alcoholysis of Zr(OiPr)4(HOiPr) or Hf(OiPr)4(HOiPr) with H2[1a] in diethyl ether solutions at -35 °C generates the corresponding five-coordinate [1a]M(OiPr)2 (M = Zr (2a), Hf (3a)) in high isolated yield. Similar reactions employing H2[1b] produce six-coordinate [1b]M(OiPr)2(HOiPr) (M = Zr (2b·HOiPr), Hf (3b·HOiPr)) as an isopropanol adduct. Repetitive trituration of 2b·HOiPr and 3b·HOiPr with diethyl ether gives five-coordinate 2b and 3b, respectively. Treatment of M(OiPr)4(HOiPr) with H2[1c] under similar conditions affords six-coordinate [1c]M(OiPr)2(HOiPr) (M = Zr (2c·HOiPr), Hf (3c·HOiPr)), subsequent recrystallization of which from acetonitrile-diethyl ether solutions leads to acetonitrile adducts 2c·MeCN and 3c·MeCN. Reactivity studies of these zirconium and hafnium complexes revealed that they are all active catalysts for ring-opening polymerization of ε-caprolactone. Among them, the N-isopropyl derived complexes are most reactive. Polymerizations catalyzed by 2b, 3b and 3c·MeCN were proved to be living. The X-ray structures of 2a·HOiPr, 2a·MeCN, 2c·HOiPr, 2c·MeCN, and 3c·MeCN are presented.

  8. Coordinating the Complexity of Tools, Tasks, and Users: On Theory-Based Approaches to Authoring Tool Usability

    Science.gov (United States)

    Murray, Tom

    2016-01-01

    Intelligent Tutoring Systems authoring tools are highly complex educational software applications used to produce highly complex software applications (i.e. ITSs). How should our assumptions about the target users (authors) impact the design of authoring tools? In this article I first reflect on the factors leading to my original 1999 article on…

  9. Controlling proton movement: electrocatalytic oxidation of hydrogen by a nickel(II) complex containing proton relays in the second and outer coordination spheres.

    Science.gov (United States)

    Das, Parthapratim; Ho, Ming-Hsun; O'Hagan, Molly; Shaw, Wendy J; Bullock, R Morris; Raugei, Simone; Helm, Monte L

    2014-02-21

    A nickel bis(diphosphine) complex containing proton relays in the second and outer coordination spheres, Ni(P(Cy)2N((CH2)2OMe))2, (P(Cy)2N((CH2)2OMe) = 1,5-di(methoxyethyl)-3,7-dicyclohexyl-1,5-diaza-3,7-diphosphacyclooctane), is an electrocatalyst for hydrogen oxidation. The addition of hydrogen to the Ni(II) complex results in rapid formation of three isomers of the doubly protonated Ni(0) complex, [Ni(P(Cy)2N((CH2)2OMe)2H)2](2+). The three isomers show fast interconversion at 40 °C, unique to this complex in this class of catalysts. Under conditions of 1.0 atm H2 using H2O as a base, catalytic oxidation proceeds at a turnover frequency of 5 s(-1) and an overpotential of 720 mV, as determined from the potential at half of the catalytic current. Compared to the previously reported Ni(P(Cy)2N(Bn))2 complex, the new complex operates at a faster rate and at a lower overpotential.

  10. Synthesis and Coordination Mechanism of Complex of Troxerutin and Lanthanum%曲克芦丁镧配合物的制备和机理探讨

    Institute of Scientific and Technical Information of China (English)

    尹慧; 徐启杰; 时文中; 刘大勇; 左春山; 许丹丽

    2012-01-01

    In order to research the prepared conditions of the complex of troxerutin and lanthanum and its coordination mechanism, the ultraviolet absorption of the complex in different reaction conditions were measured by using spetrophotometry, and the complex of troxerutin and lanthanum was characterized by ultraviolet visible spectrophotometer (UV), infrared spectrometer (IR), and high performance liquid chromatograph (HPLC). The results show that the coordination reaction occurred between the groups containing oxygen and Laa+ , coordination mechanism is that the carbonyl oxygen on 4th position of troxerutin and the hydroxyl oxygen on 5th position reacts with La3+ , and then forms coordination bond~ the optimum conditions for preparing the complex of troxerutin with lanthanum are the ratio of troxerutin and lanthanum 2 : 1, the reaction time 4 h, temperature 55 ℃, and the solution pH 7.0.%为了探讨曲克芦丁镧配合物的形成条件及配位作用机理,利用分光光度法测定了不同反应条件对曲克芦丁镧配合物的紫外吸收的影响,并通过紫外-可见分光光度计、红外光谱仪和液相色谱仪对配合物的结构进行表征.研究结果表明,曲克芦丁结构中的氧与镧离子发生配位作用,推测曲克芦丁结构中4位上的羰基氧和5位上的羟基氧参与配位反应形成配合物;制备曲克芦丁镧配合物的适宜条件为:曲克芦丁与镧的物质的量比为2∶1、反应时间4h、反应温度55℃和反应体系pH值为7.

  11. 4th July 2011 - Russian Deputy Director-General Director of Directorate for Scientific and Technical Complex ROSATOM V. Pershukov in the ATLAS underground experimental area with Adviser T. Kurtyka, ATLAS Technical Coordinator M. Nessi and ATLAS Russian users.

    CERN Multimedia

    Maximilien Brice

    2011-01-01

    4th July 2011 - Russian Deputy Director-General Director of Directorate for Scientific and Technical Complex ROSATOM V. Pershukov in the ATLAS underground experimental area with Adviser T. Kurtyka, ATLAS Technical Coordinator M. Nessi and ATLAS Russian users.

  12. Intramolecular N-H···Cl hydrogen bonds in the outer coordination sphere of a bipyridyl bisurea-based ligand stabilize a tetrahedral FeLCl2 complex.

    Science.gov (United States)

    Gavette, Jesse V; Klug, Christina M; Zakharov, Lev N; Shores, Matthew P; Haley, Michael M; Johnson, Darren W

    2014-07-11

    A bipyridyl-based anion receptor is utilized as a ligand in a tetrahedral FeCl2 complex and demonstrates secondary coordination sphere influence through intramolecular hydrogen bonding to the chloride ligands as evidenced by X-ray crystallography.

  13. Synthesis, spectroscopic, coordination and biological activities of some transition metal complexes containing ONO tridentate Schiff base ligand.

    Science.gov (United States)

    Belal, A A M; El-Deen, I M; Farid, N Y; Zakaria, Rosan; Refat, Moamen S

    2015-01-01

    The main target of this paper is to get an interesting data for the preparation and characterizations of metal oxide (MO) nanoparticles using H2L Schiff base complexes as precursors through the thermal decomposition procedure. Five Schiff base complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) metal ions were synthesized from 2-[(2-hydroxy-naphthalen-1-ylmethylene)-amino]-benzoic acid new adduct (H2L). Theses complexes were characterized using infrared, electronic, mass and (1)H NMR spectroscopic techniques. The elemental analysis data was confirmed that the stoichiometry of (metal:H2L) is 1:1 molar ratio. The molar conductance indicates that all of complexes are non electrolytic. The general chemical formulas of these complexes is [M(L)(NH3)]·nH2O. All complexes are tetrahedral geometry. The thermal decomposition behavior of H2L hydrated and anhydrous complexes has been discussed using thermogravimetric analysis (TG/DTG) and differential thermal analyses (DTA) under nitrogen atmosphere. The crystalline phases of the reaction products were checked using X-ray diffractometer (XRD) and scanning electron microscopy (SEM). PMID:25989615

  14. A series of Zn-4f heterometallic coordination polymers and a zinc complex containing a flexible mixed donor dicarboxylate ligand.

    Science.gov (United States)

    Feng, Xun; Feng, Yu-Quan; Liu, Lang; Wang, Li-Ya; Song, Hong-Liang; Ng, Seik-Weng

    2013-06-01

    A new zinc compound, together with a corresponding series of Zn-4f heterometallic coordination polymers, namely, [Zn(H2PBDA)(PBDA)]n (1), {[Ln2(PBDA)2·2H2O] [Zn2(PBDA)2Cl2]}n [H2PBDA = 3-(pyridin-3-yl-oxy) benzene-1,2-dicarboxylic acid, and Ln = Pr(2), Nd(3), Eu(4), Gd(5), Dy(6), Ho(7), Er(8)] have been hydrothermally synthesized and characterized systematically. Polymers 2-8 feature two-dimensional (2D) 4,4 networks, containing the original 1D heterometallic double stranded chains composed of [Ln2Zn2(PBDA)2] entities. The extensive hydrogen bonding and π-π stacking interactions were observed to stabilize the extended architectures. The luminescence emission spectra of the polymers vary depending on the lanthanide(III) ion present. Informative magnetic susceptibility measurements show that the same carboxylate bridging fashion of the PBDA ligand results in the different magnetic properties occurring within the heterometallic coordination polymers. In addition, polymer 6 exhibits an interesting slow magnetic relaxation behavior at lower temperatures.

  15. A spectroscopic study on the coordination and solution structures of the interaction systems between biperoxidovanadate complexes and the pyrazolylpyridine-like ligands.

    Science.gov (United States)

    Yu, Xian-Yong; Deng, Lin; Zheng, Baishu; Zeng, Bi-Rong; Yi, Pinggui; Xu, Xin

    2014-01-28

    In order to understand the substitution effects of pyrazolylpyridine (pzpy) on the coordination reaction equilibria, the interactions between a series of pzpy-like ligands and biperoxidovanadate ([OV(O2)2(D2O)](-)/[OV(O2)2(HOD)](-), abbrv. bpV) have been explored using a combination of multinuclear ((1)H, (13)C, and (51)V) magnetic resonance, heteronuclear single quantum coherence (HSQC), and variable temperature NMR in a 0.15 mol L(-1) NaCl D2O solution that mimics the physiological conditions. Both the direct NMR data and the equilibrium constants are reported for the first time. A series of new hepta-coordinated peroxidovanadate species [OV(O2)2L](-) (L = pzpy-like chelating ligands) are formed due to several competitive coordination interactions. According to the equilibrium constants for products between bpV and the pzpy-like ligands, the relative affinity of the ligands is found to be pzpy > 2-Ester-pzpy ≈ 2-Me-pzpy ≈ 2-Amide-pzpy > 2-Et-pzpy. In the interaction system between bpV and pzpy, a pair of isomers (Isomers A and B) are observed in aqueous solution, which are attributed to different types of coordination modes between the metal center and the ligands, while the crystal structure of NH4[OV(O2)2(pzpy)]·6H2O (CCDC 898554) has the same coordination structure as Isomer A (the main product for pzpy). For the N-substituted ligands, however, Isomer A or B type complexes can also be observed in solution but the molar ratios of the isomer are reversed (i.e., Isomer B type is the main product). These results demonstrate that when the N atom in the pyrazole ring has a substitution group, hydrogen bonding (from the H atom in the pyrazole ring), the steric effect (from alkyl) and the solvation effect (from the ester or amide group) can jointly affect the coordination reaction equilibrium.

  16. A spectroscopic study on the coordination and solution structures of the interaction systems between biperoxidovanadate complexes and the pyrazolylpyridine-like ligands.

    Science.gov (United States)

    Yu, Xian-Yong; Deng, Lin; Zheng, Baishu; Zeng, Bi-Rong; Yi, Pinggui; Xu, Xin

    2014-01-28

    In order to understand the substitution effects of pyrazolylpyridine (pzpy) on the coordination reaction equilibria, the interactions between a series of pzpy-like ligands and biperoxidovanadate ([OV(O2)2(D2O)](-)/[OV(O2)2(HOD)](-), abbrv. bpV) have been explored using a combination of multinuclear ((1)H, (13)C, and (51)V) magnetic resonance, heteronuclear single quantum coherence (HSQC), and variable temperature NMR in a 0.15 mol L(-1) NaCl D2O solution that mimics the physiological conditions. Both the direct NMR data and the equilibrium constants are reported for the first time. A series of new hepta-coordinated peroxidovanadate species [OV(O2)2L](-) (L = pzpy-like chelating ligands) are formed due to several competitive coordination interactions. According to the equilibrium constants for products between bpV and the pzpy-like ligands, the relative affinity of the ligands is found to be pzpy > 2-Ester-pzpy ≈ 2-Me-pzpy ≈ 2-Amide-pzpy > 2-Et-pzpy. In the interaction system between bpV and pzpy, a pair of isomers (Isomers A and B) are observed in aqueous solution, which are attributed to different types of coordination modes between the metal center and the ligands, while the crystal structure of NH4[OV(O2)2(pzpy)]·6H2O (CCDC 898554) has the same coordination structure as Isomer A (the main product for pzpy). For the N-substituted ligands, however, Isomer A or B type complexes can also be observed in solution but the molar ratios of the isomer are reversed (i.e., Isomer B type is the main product). These results demonstrate that when the N atom in the pyrazole ring has a substitution group, hydrogen bonding (from the H atom in the pyrazole ring), the steric effect (from alkyl) and the solvation effect (from the ester or amide group) can jointly affect the coordination reaction equilibrium. PMID:24213652

  17. XRCC1 coordinates disparate responses and multiprotein repair complexes depending on the nature and context of the DNA damage

    DEFF Research Database (Denmark)

    Hanssen-Bauer, Audun; Solvang-Garten, Karin; Sundheim, Ottar;

    2011-01-01

    XRCC1 is a scaffold protein capable of interacting with several DNA repair proteins. Here we provide evidence for the presence of XRCC1 in different complexes of sizes from 200 to 1500 kDa, and we show that immunoprecipitates using XRCC1 as bait are capable of complete repair of AP sites via both...... proteins to sites of DNA damage and provide evidence for a role of XRCC1 in the organization of BER into multiprotein complexes of different sizes....

  18. Low-dimensional coordination polymeric structures in alkali metal complex salts of the herbicide (2,4-dichlorophenoxy)acetic acid (2,4-D).

    Science.gov (United States)

    Smith, Graham

    2015-02-01

    The Li, Rb and Cs complexes with the herbicide (2,4-dichlorophenoxy)acetic acid (2,4-D), namely poly[[aqua[μ3-(2,4-dichlorophenoxy)acetato-κ(3)O(1):O(1):O(1')]lithium(I)] dihydrate], {[Li(C8H5Cl2O3)(H2O)]·2H2O}n, (I), poly[μ-aqua-bis[μ3-(2,4-dichlorophenoxy)acetato-κ(4)O(1):O(1'):O(1'),Cl(2)]dirubidium(I)], [Rb2(C8H5Cl2O3)2(H2O)]n, (II), and poly[μ-aqua-bis[μ3-(2,4-dichlorophenoxy)acetato-κ(5)O(1):O(1'):O(1'),O(2),Cl(2)]dicaesium(I)], [Cs2(C8H5Cl2O3)2(H2O)]n, (III), respectively, have been determined and their two-dimensional polymeric structures are described. In (I), the slightly distorted tetrahedral LiO4 coordination involves three carboxylate O-atom donors, of which two are bridging, and a monodentate aqua ligand, together with two water molecules of solvation. Conjoined six-membered ring systems generate a one-dimensional coordination polymeric chain which extends along b and interspecies water O-H...O hydrogen-bonding interactions give the overall two-dimensional layers which lie parallel to (001). In hemihydrate complex (II), the irregular octahedral RbO5Cl coordination about Rb(+) comprises a single bridging water molecule which lies on a twofold rotation axis, a bidentate O(carboxy),Cl-chelate interaction and three bridging carboxylate O-atom bonding interactions from the 2,4-D ligand. A two-dimensional coordination polymeric layer structure lying parallel to (100) is formed through a number of conjoined cyclic bridges, including a centrosymmetric four-membered Rb2O2 ring system with an Rb...Rb separation of 4.3312 (5) Å. The coordinated water molecule forms intralayer aqua-carboxylate O-H...O hydrogen bonds. Complex (III) comprises two crystallographically independent (Z' = 2) irregular CsO6Cl coordination centres, each comprising two O-atom donors (carboxylate and phenoxy) and a ring-substituted Cl-atom donor from the 2,4-D ligand species in a tridentate chelate mode, two O-atom donors from bridging carboxylate groups and one from a

  19. Synthesis, Crystal Structures and Catalysis of Dinuclear Cd(Ⅱ) Complexes Bridged by Unusual (N,O,O')-Coordinated a-Amino Acids

    Institute of Scientific and Technical Information of China (English)

    DENG Dong-sheng; WANG Li; PEI Ya-mei; FENG Lu; LIU Chang-lin

    2012-01-01

    Four dinuclear amino acid cadmium(Ⅱ) complexes [Cd2(tren)2(dl-alaninato)](ClO4)3·H2O(Ⅰ),[Cd2(tren)2·(l-alaninato)](ClO4)3·H2O(Ⅱ),[Cd2(tren)2(dl-phenylalaninato)](ClO4)3(Ⅲ) and [Cd2(tren)2(l-phenylalaninato)]·(ClO4)3(Ⅳ),constructed from mixed ligands of tris(2-aminoethyl)amine(tren) and racemic or natural amino acids(amino acids=dl- or l-alanine,and dl- or l-phenylalanine),have been synthesized and characterized by X-ray crystallography.The structural analysis of complexes Ⅰ and Ⅲ reveals that the cadmium centers are coordinated by one tren ligand and one amino acid molecule with the unusual (N,O,O')-bridged mode,resulting in asymmetric chromophores of CdN4O and CdN5O in complex Ⅰ,CdN4O2 and CdN5O in complex Ⅲ,respectively.The utility of the four complexes as efficient water-compatible Lewis acid catalysts for the direct aldol reaction in water was examined.The reaction proceeded smoothly to afford the corresponding β-hydroxy ketones in up to 99% yield.Moreover,the diastereoselectivity of the reaction favors the formation of the syn-isomers.

  20. Examination of the coordination sphere of Al(III) in trifluoromethyl-heteroarylalkenolato complex ions by gas-phase IRMPD spectroscopy and computational modelling.

    Science.gov (United States)

    Brückmann, Lisa; Tyrra, Wieland; Mathur, Sanjay; Berden, Giel; Oomens, Jos; Meijer, Anthony J H M; Schäfer, Mathias

    2012-06-01

    A series of aluminium complex ions with trifluoromethyl-heteroarylalkenolato (TMHA) ligands are studied by gas-phase infrared multiphoton-dissociation (IRMPD) spectroscopy and computational modelling. The selected series of aluminium TMHA complex ions are promising species for the initial study of intrinsic binding characteristics of Al(III) cations in the gas phase as corresponding molecular ions. They are readily available for examination by (+) and (-) electrospray ionization mass spectrometry (ESI-MS) by spraying of [Al(3+)⋅(L(-))(3)] solutions. The complex ions under investigation contain trivalent Al(3+) cations with two chelating anionic enolate ligands, [Al(3+)⋅(L(-))(2)](+), providing insights in the nature of the heteroatom-Al bonds. Additionally, the structure of a deprotonated benzimidazole ligand, L(-,) and an anionic complex ion of Al(III) with two doubly deprotonated benzimidazole ligands, [Al(3+)⋅(L(2-))(2)](-), are examined by (-)ESI-IRMPD spectroscopy. Experimental and computational results are highly consistent and allow a reliable identification of the ion structures. In all complex ions examined the planar TMHA ligands are oriented perpendicular to each other around the metal ion, leading to a tetrahedral coordination sphere in which aluminium interacts with the enolate oxygen and heteroaryl nitrogen atoms available in each of the bidentate ligands.

  1. Examination of the coordination sphere of Al(III) in trifluoromethyl-heteroarylalkenolato complex ions by gas-phase IRMPD spectroscopy and computational modelling.

    Science.gov (United States)

    Brückmann, Lisa; Tyrra, Wieland; Mathur, Sanjay; Berden, Giel; Oomens, Jos; Meijer, Anthony J H M; Schäfer, Mathias

    2012-06-01

    A series of aluminium complex ions with trifluoromethyl-heteroarylalkenolato (TMHA) ligands are studied by gas-phase infrared multiphoton-dissociation (IRMPD) spectroscopy and computational modelling. The selected series of aluminium TMHA complex ions are promising species for the initial study of intrinsic binding characteristics of Al(III) cations in the gas phase as corresponding molecular ions. They are readily available for examination by (+) and (-) electrospray ionization mass spectrometry (ESI-MS) by spraying of [Al(3+)⋅(L(-))(3)] solutions. The complex ions under investigation contain trivalent Al(3+) cations with two chelating anionic enolate ligands, [Al(3+)⋅(L(-))(2)](+), providing insights in the nature of the heteroatom-Al bonds. Additionally, the structure of a deprotonated benzimidazole ligand, L(-,) and an anionic complex ion of Al(III) with two doubly deprotonated benzimidazole ligands, [Al(3+)⋅(L(2-))(2)](-), are examined by (-)ESI-IRMPD spectroscopy. Experimental and computational results are highly consistent and allow a reliable identification of the ion structures. In all complex ions examined the planar TMHA ligands are oriented perpendicular to each other around the metal ion, leading to a tetrahedral coordination sphere in which aluminium interacts with the enolate oxygen and heteroaryl nitrogen atoms available in each of the bidentate ligands. PMID:22442004

  2. Crystal structure of yeast monothiol glutaredoxin Grx6 in complex with a glutathione-coordinated [2Fe–2S] cluster

    Science.gov (United States)

    Abdalla, Mohnad; Dai, Ya-Nan; Chi, Chang-Biao; Cheng, Wang; Cao, Dong-Dong; Zhou, Kang; Ali, Wafa; Chen, Yuxing; Zhou, Cong-Zhao

    2016-01-01

    Glutaredoxins (Grxs) constitute a superfamily of proteins that perform diverse biological functions. The Saccharomyces cerevisiae glutaredoxin Grx6 not only serves as a glutathione (GSH)-dependent oxidoreductase and as a GSH transferase, but also as an essential [2Fe–2S]-binding protein. Here, the dimeric structure of the C-terminal domain of Grx6 (holo Grx6C), bridged by one [2Fe–2S] cluster coordinated by the active-site Cys136 and two external GSH molecules, is reported. Structural comparison combined with multiple-sequence alignment demonstrated that holo Grx6C is similar to the [2Fe–2S] cluster-incorporated dithiol Grxs, which share a highly conserved [2Fe–2S] cluster-binding pattern and dimeric conformation that is distinct from the previously identified [2Fe–2S] cluster-ligated monothiol Grxs. PMID:27710937

  3. MALDI-TOFMS analysis of coordination and organometallic complexes: a nic(h)e area to work in.

    Science.gov (United States)

    Wyatt, Mark F

    2011-07-01

    A mini-review of the characterisation of metal-containing compounds by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) is presented. Organometallic and coordination compounds have many varied applications, most notably in industrial catalytic processes and also in the electronics and healthcare sectors. In general, the compounds discussed, be they small or large molecules, have a high percentage metal content, rather than simply containing 'a metal atom'. A brief history of the field is given, but the main scope over the last 5 years is covered in some detail. How MALDI-TOFMS compliments electrospray for metal-containing compounds is highlighted. Perspectives on recent advances, such as solvent-free and air/moisture-sensitive sample preparation, and potential future challenges and developments, such as nanomaterials and metallodrug/metallometabolite imaging, are given.

  4. Conformation driven complexation of two analogous benzimidazole based tripodal ligands with Ag(I) resulting in a trigonal prism and a coordination polymer

    Indian Academy of Sciences (India)

    Suman Bhattacharya; Binoy K Saha

    2016-02-01

    Two analogous tripodal ligands, namely, 1,3,5-tris(benzimidazol-1-ylmethyl)-2,4,6-triethylbenzene (1-Et) and 1,3,5-tris(benzimidazol-1-ylmethyl)-2,4,6-trimethoxybenzene (1-OMe) have been used for complexation with silver(I) tetrafluoroborate. A trinuclear Ag(I) salt, formulated as $\\mathbf{[Ag_3(1-Et)_2]^{3+}(BF_4){}^{−}_{3}\\bullet 7CH_3CN\\bullet yH_2O}$ was formed in the complexation reaction of 1-Et with silver(I) tetrafluoroborate, which consists of a trigonal prismatic cation formed by three bicoordinated Ag(I) coordinated with two 1-Et ligands. In case of the 1-OMe ligand, however, a one dimensional ladder, formulated as $\\mathbf{[(Ag(1-OMe)OH_2)^{+}(BF_4)^{−}\\bullet MeOH]_{\\infty}}$ was obtained which is constituted of a tetracoordinated Ag(I) center in a distorted tetrahedral environment. The crystal structures of the ligand hydrates namely $\\mathbf{1-Et\\bullet H_2O}$ and $\\mathbf{1-OMe\\bullet 3.6H_2O}$ have been discussed along with the structure of methanol solvate-hydrate of 1-Et. The imidazole rings of the Bim groups in 1-Et in the crystal structures of the ligand as well as in its coordination complex with the Ag(I) are pointed inward with respect to the central ring, whereas it is pointed outwards in the crystal structures of 1-OMe as well as its Ag(I) complex.

  5. Extending the NIF DISCO framework to automate complex workflow: coordinating the harvest and integration of data from diverse neuroscience information resources

    Directory of Open Access Journals (Sweden)

    Luis eMarenco

    2014-05-01

    Full Text Available This paper describes how DISCO, the data-aggregator that supports the Neuroscience Information Framework (NIF, has been extended to play a central role in automating the complex workflow required to support and coordinate the NIF's data integration capabilities. The NIF is an NIH Neuroscience Blueprint initiative designed to help researchers access the wealth of data related to the neurosciences available via the Internet. A central component is the NIF Federation, a searchable database that currently contains data from 231 data and information resources regularly harvested, updated, and warehoused in the DISCO system. In the past several years, DISCO has greatly extended its functionality and has evolved to play a central role in automating the complex, ongoing process of harvesting, validating, integrating, and displaying neuroscience data from a growing set of participating resources. This paper provides an overview of DISCO's current capabilities and discusses a number of the challenges and future directions related to the process of coordinating the integration of neuroscience data within the NIF Federation.

  6. Extending the NIF DISCO framework to automate complex workflow: coordinating the harvest and integration of data from diverse neuroscience information resources.

    Science.gov (United States)

    Marenco, Luis N; Wang, Rixin; Bandrowski, Anita E; Grethe, Jeffrey S; Shepherd, Gordon M; Miller, Perry L

    2014-01-01

    This paper describes how DISCO, the data aggregator that supports the Neuroscience Information Framework (NIF), has been extended to play a central role in automating the complex workflow required to support and coordinate the NIF's data integration capabilities. The NIF is an NIH Neuroscience Blueprint initiative designed to help researchers access the wealth of data related to the neurosciences available via the Internet. A central component is the NIF Federation, a searchable database that currently contains data from 231 data and information resources regularly harvested, updated, and warehoused in the DISCO system. In the past several years, DISCO has greatly extended its functionality and has evolved to play a central role in automating the complex, ongoing process of harvesting, validating, integrating, and displaying neuroscience data from a growing set of participating resources. This paper provides an overview of DISCO's current capabilities and discusses a number of the challenges and future directions related to the process of coordinating the integration of neuroscience data within the NIF Federation.

  7. The loading of coordination complex modified polyoxometalate nanobelts on activated carbon fiber: a feasible strategy to obtain visible light active and highly efficient polyoxometalate based photocatalysts.

    Science.gov (United States)

    Lu, Tingting; Xu, Xinxin; Li, Huili; Li, Zhenyu; Zhang, Xia; Ou, Jinzhao; Mei, Mingliang

    2015-02-01

    To enhance the photocatalytic properties of coordination complex modified polyoxometalates (CC/POMs) in the visible light region, its nanobelts (CC/POMNBs) were loaded on activated carbon fiber (ACF) through a simple colloidal blending process. The resulting coordination complex modified polyoxometalate nanobelts loaded activated carbon fiber composite materials (CC/POMNBs/ACF) exhibited dramatic photocatalytic activity for the degradation of rhodamine B (RhB) under visible light irradiation. Optical and electrochemical methods illustrated the enhanced photocatalytic activity of CC/POMNBs/ACF, which originates from the high separation efficiency of the photogenerated electrons and holes on the interface of the CC/POMNBs and ACF, which results from the synergistic effects between them. In the composite material, the role of ACF could be described as a photosensitizer and a good electron transporter. Furthermore, the influence of the mass ratio between the CC/POMNBs and ACF on the photocatalytic performance of the resulting composite material was discussed, and an ideal value to obtain highly efficient photocatalysts was obtained. The results suggested that the loading of CC/POMNBs on the surface of ACF would be a feasible strategy to enhance their photocatalytic activity.

  8. Magnetic adsorbent constructed from the loading of amino functionalized Fe3O4 on coordination complex modified polyoxometalates nanoparticle and its tetracycline adsorption removal property study

    Science.gov (United States)

    Ou, Jinzhao; Mei, Mingliang; Xu, Xinxin

    2016-06-01

    A magnetic polyoxometalates based adsorbent has been synthesized successfully through the loading of amino functionalized Fe3O4 (NH2-Fe3O4) on nanoparticle of a coordination complex modified polyoxometalates (CC/POMNP). FTIR illustrate there exist intense hydrogen bonds between NH2-Fe3O4 and CC/POMNP, which keep the stability of this adsorbent. At room temperature, this adsorbent exhibits ferromagnetic character with saturation magnetization of 8.19 emu g-1, which provides prerequisite for fast magnetic separation. Water treatment experiment illustrates this POM based magnetic adsorbent exhibits high adsorption capacity on tetracycline. The adsorption process can be described well with Temkin model, which illustrates the interaction between adsorbent and tetracycline plays the dominated role in tetracycline removal. The rapid, high efficient tetracycline adsorption ability suggests this POM based magnetic adsorbent exhibits promising prospect in medical and agriculture waste water purification. A magnetic polyoxometalates based adsorbent, which exhibits excellent tetracycline adsorption removal property has been synthesized through the loading of NH2-Fe3O4 on coordination complex modified polyoxometalates

  9. Coordinated regulation of transcriptional repression by the RBP2 H3K4 demethylase and Polycomb-Repressive Complex 2

    DEFF Research Database (Denmark)

    Pasini, Diego; Hansen, Klaus H; Christensen, Jesper;

    2008-01-01

    Polycomb group (PcG) proteins regulate important cellular processes such as embryogenesis, cell proliferation, and stem cell self-renewal through the transcriptional repression of genes determining cell fate decisions. The Polycomb-Repressive Complex 2 (PRC2) is highly conserved during evolution......, and its intrinsic histone H3 Lys 27 (K27) trimethylation (me3) activity is essential for PcG-mediated transcriptional repression. Here, we show a functional interplay between the PRC2 complex and the H3K4me3 demethylase Rbp2 (Jarid1a) in mouse embryonic stem (ES) cells. By genome-wide location analysis we...... found that Rbp2 is associated with a large number of PcG target genes in mouse ES cells. We show that the PRC2 complex recruits Rbp2 to its target genes, and that this interaction is required for PRC2-mediated repressive activity during ES cell differentiation. Taken together, these results demonstrate...

  10. Molybdenum complexes of biochemical interest. New coordination complexes of oxomolybdenum(V) with the tridentate ONO donor Schiff bases derived from salicylaldehydes and ethanolamine

    International Nuclear Information System (INIS)

    New oxomolybdenum(V) complexes MoOClL (where LH2 = Schiff base) derived from ethanolamine and salicylaldehyde, 5-chlorosalicylaldehyde, 5-bromosalicylaldehyde, 5-nitrosalicylaldehyde, 3-ethoxysalicylaldehyde and 2-hydroxy-1-naphthaldehyde have been synthesized and characterised by elemental analyses, conductance, molecular weight, i.r. and electronic spectra and magnetic measurements. The Schiff bases behave as dibasic tridentate ONO donor ligands. The complexes are non-electrolytes and dimers. The complexes exhibit subnormal magnetic moments and are involved in antiferromagnetic exchange with S = 0 ground state. The complexes exhibit electronic spectral bands at ca. 13000 and ca. 17000 cm-1 due to the transitions dsub(xy)->dsub(xz,yz) (2B2->2E) and dsub(xy)->dsub(x2-y2) (2B2->2B1), respectively. The ν(Mo=O) frequency of the complexes is observed in the 900-970 cm-1 region. On the basis of the magnetic susceptibility, i.r. and molecular weight data a dimetallic structure with alcoholic oxygen atoms as the bridging atoms is suggested. (orig.)

  11. Interfacial Charge Transfer in Dye-Sensitized Solar Cells Using SCN-Free Terpyridine-Coordinated Ru Complex Dye and Co Complex Redox Couples.

    Science.gov (United States)

    Kono, Takahiro; Masaki, Naruhiko; Nishikawa, Masahiro; Tamura, Rei; Matsuzaki, Hiroyuki; Kimura, Mutsumi; Mori, Shogo

    2016-07-01

    The efficiency of dye-sensitized solar cells (DSSCs) using Ru complex dyes and Co complex redox couples has been increased with a strategy to prevent charge recombination via the addition of bulky or lengthy peripheral units to the dyes. However, despite the efforts, most of the DSSCs are still suffering from nonunity quantum efficiency and fast recombination. We examine the effect of SCN ligand, which has been used for many Ru complex dyes and could attract positively charged Co complexes. We find that replacing the ligands with 2,6-bis(2'-(4'-trifluoromethyl)pyrazolyl)pyridine increases the quantum efficiency and electron lifetime. With the combination of the replacement of SCN ligands and the addition of bulky moiety, ∼80% external quantum efficiency is achieved. These suggest that not only the addition of a blocking effect but also the reduction of electrostatic and dispersion forces between dyes and Co complexes are essential to control the charge separation and recombination processes. PMID:27328462

  12. Synthesis, structure and antifungal activity of thiophene-2,3-dicarboxaldehyde bis(thiosemicarbazone) and nickel(II), copper(II) and cadmium(II) complexes: unsymmetrical coordination mode of nickel complex.

    Science.gov (United States)

    Alomar, Kusaï; Landreau, Anne; Allain, Magali; Bouet, Gilles; Larcher, Gérald

    2013-09-01

    The reaction of nickel(II), copper(II) chlorides and cadmium(II) chloride and bromide with thiophene-2,3-dicarboxaldehyde bis(thiosemicarbazone) (2,3BTSTCH2) leads to a series of new complexes: [Ni(2,3BTSTCH)]Cl, [Cu(2,3BTSTC)], [CdCl2(2,3BTSTCH2)] and [CdBr2(2,3BTSTCH2)]. The crystal structures of the ligand and of [Ni(2,3BTSTCH)]Cl complex have been determined. In this case, we remark an unusual non-symmetrical coordination mode for the two functional groups: one acting as a thione and the second as a deprotonated thiolate. All compounds have been tested for their antifungal activity against human pathogenic fungi: Candida albicans, Candida glabrata and Aspergillus fumigatus, the cadmium complexes exhibit the highest antifungal activity. Cytotoxicity was evaluated using two biological methods: human MRC5 cultured cells and brine shrimp Artemia salina bioassay.

  13. Coordination chemistry of actinide elements: preparation of new uranium complexes with schiff bases and their characterization (Preprint No. CT-31)

    International Nuclear Information System (INIS)

    The Schiff bases, o-vanillin semicarbazone (oVSC) and 2-pyridine carboxaldehyde isonicotinoyl hydrazone (PCINH) have been prepared and their novel complexes with dioxouranium(VI) have been synthesized and characterized by IR spectra, elemental analysis and other physico-chemical techniques. (author)

  14. Coordination ligand exchange of a xanthene probe-Ce(III) complex for selective fluorescence sensing of inorganic pyrophosphate.

    Science.gov (United States)

    Kittiloespaisan, Ekkachai; Takashima, Ippei; Kiatpathomchai, Wansika; Wongkongkatep, Jirarut; Ojida, Akio

    2014-02-28

    A fluorescence sensing system for inorganic pyrophosphate based on ligand exchange of the Ce(III) complex of a xanthene-type probe is developed. This sensing system is successfully applied to the fluorescence detection of polymerase-catalyzed DNA amplification using loop-mediated isothermal amplification.

  15. Diffusion tensor imaging metrics of the corpus callosum in relation to bimanual coordination : Effect of task complexity and sensory feedback

    NARCIS (Netherlands)

    Gooijers, Jolien; Caeyenberghs, Karen; Sisti, Helene M.; Geurts, Monique; Heitger, Marcus H.; Leemans, Alexander; Swinnen, Stephan P.

    2013-01-01

    When manipulating objects with both hands, the corpus callosum (CC) is of paramount importance for interhemispheric information exchange. Hence, CC damage results in impaired bimanual performance. Here, healthy young adults performed a complex bimanual dial rotation task with or without augmented vi

  16. Influence of the π-coordinated arene on the anticancer activity of ruthenium(II) carbohydrate organometallic complexes

    NARCIS (Netherlands)

    Hanif, Muhammad; Meier, Samuel M; Nazarov, Alexey A; Risse, Julie; Legin, Anton; Casini, Angela; Jakupec, Michael A; Keppler, Bernhard K; Hartinger, Christian G

    2013-01-01

    The synthesis and in vitro cytotoxicity of a series of Ru(II)(arene) complexes with carbohydrate-derived phosphite ligands and various arene co-ligands is described. The arene ligand has a strong influence on the in vitro anticancer activity of this series of compounds, which correlates fairly well

  17. Chiral metal complexes. 4. Stereoselective deuterium exchange at the coordinated NH/sub 2/ group of L-alanine

    Energy Technology Data Exchange (ETDEWEB)

    Vagg, R.S. (Macquarie Univ., North Ryde, Australia); Williams, P.A.

    1983-01-19

    This communication details results of initial /sup 1/H NMR investigations on one of the simplest of these ternary compounds, namely ..delta..,..lambda..-((L-alaninato)bis(2,2-bipyridine)ruthenium(II)) perchlorate. Possible mechanisms of deuterium exchange for chiral ruthenium complexes are presented in this study.

  18. Crystal structures of bis- and hexakis[(6,6'-di-hydroxy-bipyridine)copper(II)] nitrate coordination complexes.

    Science.gov (United States)

    Gerlach, Deidra L; Nieto, Ismael; Herbst-Gervasoni, Corey J; Ferrence, Gregory M; Zeller, Matthias; Papish, Elizabeth T

    2015-12-01

    Two multinuclear complexes synthesized from Cu(NO3)2 and 6,6'-di-hydroxy-bipyridine (dhbp) exhibit bridging nitrate and hydroxide ligands. The dinuclear complex (6,6'-di-hydroxy-bipyridine-2κ(2) N,N')[μ-6-(6-hy-droxy-pyridin-2-yl)pyridin-2-olato-1:2κ(3) N,N':O (2)](μ-hydroxido-1:2κ(2) O:O')(μ-nitrato-1:2κ(2) O:O')(nitrato-1κO)dicopper(II), [Cu2(C10H7N2O2)(OH)(NO3)2(C10H8N2O2)] or [Cu(6-OH-6'-O-bpy)(NO3)(μ-OH)(μ-NO3)Cu(6,6'-dhbp)], (I), with a 2:1 ratio of nitrate to hydroxide anions and one partially deprotonated dhbp ligand, forms from a water-ethanol mixture at neutral pH. The hexa-nuclear complex bis-(μ3-bi-pyridine-2,2'-diolato-κ(3) O:N,N':O')tetra-kis-(6,6'-di-hydroxy-bipyridine-κ(2) N,N')tetra-kis-(μ-hydroxido-κ(2) O:O')bis-(methanol-κO)tetra-kis-(μ-nitrato-κ(2) O:O')hexa-copper(II), [Cu6(C10H6N2O2)2(CH4O)2(OH)4(NO3)4(C10H8N2O2)4] or [Cu(6,6'-dhbp)(μ-NO3)2(μ-OH)Cu(6,6'-O-bpy)(μ-OH)Cu(6,6'dhbp)(CH3OH)]2, (II), with a 1:1 NO3-OH ratio and two fully protonated and fully deprotonated dhbp ligands, was obtained by methanol recrystallization of material obtained at pH 3. Complex (II) lies across an inversion center. Complexes (I) and (II) both display intra-molecular O-H⋯O hydrogen bonding. Inter-molecular O-H⋯O hydrogen bonding links symmetry-related mol-ecules forming chains along [100] for complex (I) with π-stacking along [010] and [001]. Complex (II) forms inter-molecular O-H⋯O hydrogen-bonded chains along [010] with π-stacking along [100] and [001]. PMID:26870402

  19. Crystal structures of bis- and hexakis[(6,6'-di-hydroxy-bipyridine)copper(II)] nitrate coordination complexes.

    Science.gov (United States)

    Gerlach, Deidra L; Nieto, Ismael; Herbst-Gervasoni, Corey J; Ferrence, Gregory M; Zeller, Matthias; Papish, Elizabeth T

    2015-12-01

    Two multinuclear complexes synthesized from Cu(NO3)2 and 6,6'-di-hydroxy-bipyridine (dhbp) exhibit bridging nitrate and hydroxide ligands. The dinuclear complex (6,6'-di-hydroxy-bipyridine-2κ(2) N,N')[μ-6-(6-hy-droxy-pyridin-2-yl)pyridin-2-olato-1:2κ(3) N,N':O (2)](μ-hydroxido-1:2κ(2) O:O')(μ-nitrato-1:2κ(2) O:O')(nitrato-1κO)dicopper(II), [Cu2(C10H7N2O2)(OH)(NO3)2(C10H8N2O2)] or [Cu(6-OH-6'-O-bpy)(NO3)(μ-OH)(μ-NO3)Cu(6,6'-dhbp)], (I), with a 2:1 ratio of nitrate to hydroxide anions and one partially deprotonated dhbp ligand, forms from a water-ethanol mixture at neutral pH. The hexa-nuclear complex bis-(μ3-bi-pyridine-2,2'-diolato-κ(3) O:N,N':O')tetra-kis-(6,6'-di-hydroxy-bipyridine-κ(2) N,N')tetra-kis-(μ-hydroxido-κ(2) O:O')bis-(methanol-κO)tetra-kis-(μ-nitrato-κ(2) O:O')hexa-copper(II), [Cu6(C10H6N2O2)2(CH4O)2(OH)4(NO3)4(C10H8N2O2)4] or [Cu(6,6'-dhbp)(μ-NO3)2(μ-OH)Cu(6,6'-O-bpy)(μ-OH)Cu(6,6'dhbp)(CH3OH)]2, (II), with a 1:1 NO3-OH ratio and two fully protonated and fully deprotonated dhbp ligands, was obtained by methanol recrystallization of material obtained at pH 3. Complex (II) lies across an inversion center. Complexes (I) and (II) both display intra-molecular O-H⋯O hydrogen bonding. Inter-molecular O-H⋯O hydrogen bonding links symmetry-related mol-ecules forming chains along [100] for complex (I) with π-stacking along [010] and [001]. Complex (II) forms inter-molecular O-H⋯O hydrogen-bonded chains along [010] with π-stacking along [100] and [001].

  20. Four-coordinate cobalt pincer complexes: electronic structure studies and ligand modification by homolytic and heterolytic pathways.

    Science.gov (United States)

    Semproni, Scott P; Milsmann, Carsten; Chirik, Paul J

    2014-06-25

    A family of cobalt chloride, methyl, acetylide and hydride complexes bearing both intact and modified tert-butyl substituted bis(phosphino)pyridine pincer ligands has been synthesized and structurally characterized and their electronic structures evaluated. Treatment of the unmodified compounds with the stable nitroxyl radical, TEMPO (2,2,6,6-tetramethylpiperidin-1-yloxidanyl) resulted in immediate H- atom abstraction from the benzylic position of the chelate yielding the corresponding modified pincer complexes, ((tBu)mPNP)CoX (X = H, CH3, Cl, CCPh). Thermolysis of the methyl and hydride derivatives, ((tBu)PNP)CoCH3 and ((tBu)PNP)CoH, at 110 °C also resulted in pincer modification by H atom loss while the chloride and acetylide derivatives proved inert. The relative ordering of benzylic C-H bond strengths was corroborated by H atom exchange experiments between appropriate intact and modified pincer complexes. The electronic structures of the modified compounds, ((tBu)mPNP)CoX were established by EPR spectroscopy and DFT computations and are best described as low spin Co(II) complexes with no evidence for ligand centered radicals. The electronic structures of the intact complexes, ((tBu)PNP)CoX were studied computationally and bond dissociation free energies of the benzylic C-H bonds were correlated to the identity of the X-type ligand on cobalt where pure σ donors such as hydride and methyl produce the weakest C-H bonds. Comparison to a rhodium congener highlights the impact of the energetically accessible one-electron redox couple of the first row metal ion in generating weak C-H bonds in remote positions of the supporting pincer ligand. PMID:24897302

  1. New in situ generated acylhydrazidate-coordinated complexes and acylhydrazide molecules: Synthesis, structural characterization and photoluminescence property.

    Science.gov (United States)

    Wang, Yan-Ning; Huo, Qi-Sheng; Zhang, Ping; Yu, Jie-Hui; Xu, Ji-Qing

    2016-10-01

    By utilizing the hydrothermal in situ acylation of organic acids with N2H4, three acylhydrazidate-coordinated compounds [Mn(L1)2(H2O)2] (L1=2,3-quinolinedicarboxylhydrazidate; HL1=2,3-dihydropyridazino[4,5-b] quinoline-1,4-dione) 1, [Mn2(ox)(L2)2(H2O)6]·2H2O (L2=benzimidazolate-5,6-dicarboxylhydrazide; HL2=6,7-dihydro-1H-imidazo[4,5-g]phthalazine-5,8-dione; ox=oxalate) 2, and [Cd(HL3)(bpy)] (L3=4,5-di(3'-carboxylphenyl)phthalhydrazidate; H3L3=6,7-dihydro-1H-imidazo[4,5-g]phthalazine-5,8-dione; bpy=2,2'-bipyridine) 3, as well as two acylhydrazide molecules L4 (L4=oxepino[2,3,4-de:7,6,5-d'e']diphthalazine-4,10(5H,9H)-dione) 4 and L5 (L5=4,5-dibromophthalhydrazide; L5=6,7-dibromo-2,3-dihydrophthalazine-1,4-dione) 5 were obtained. X-ray single-crystal diffraction analysis reveals that (i) 1 only possesses a mononuclear structure, but it self-assembles into a 2-D supramolecular network via the NhydrazineH⋯Nhydrazine and OwH⋯Ohydroxylimino interactions; (ii) 2 exhibits a dinuclear structure. Ox acts as the linker, while L2 just serves as a terminal ligand; (iii) In 3, L3 acts as a 3-connected node to propagate the 7-coordinated Cd(2+) centers into a 1-D double-chain structure; (iv) 4 is a special acylhydrazide molecule. Two OH groups for the intermediates 3,3'-biphthalhydrazide further lose one water molecule to form 4; (v) 5 is a common monoacylhydrazide molecule. Via the NhydrazineH⋯Ohydrazine, OhydroxyliminoH⋯Oacylamino and the π⋯π interactions, it self-assembles into a 2-D supramolecular network. The photoluminescence analysis reveals that 4 emits light with the maxima at 510nm. PMID:27236205

  2. New in situ generated acylhydrazidate-coordinated complexes and acylhydrazide molecules: Synthesis, structural characterization and photoluminescence property

    Science.gov (United States)

    Wang, Yan-Ning; Huo, Qi-Sheng; Zhang, Ping; Yu, Jie-Hui; Xu, Ji-Qing

    2016-10-01

    By utilizing the hydrothermal in situ acylation of organic acids with N2H4, three acylhydrazidate-coordinated compounds [Mn(L1)2(H2O)2] (L1 = 2,3-quinolinedicarboxylhydrazidate; HL1 = 2,3-dihydropyridazino[4,5-b] quinoline-1,4-dione) 1, [Mn2(ox)(L2)2(H2O)6]·2H2O (L2 = benzimidazolate-5,6-dicarboxylhydrazide; HL2 = 6,7-dihydro-1H-imidazo[4,5-g]phthalazine-5,8-dione; ox = oxalate) 2, and [Cd(HL3)(bpy)] (L3 = 4,5-di(3‧-carboxylphenyl)phthalhydrazidate; H3L3 = 6,7-dihydro-1H-imidazo[4,5-g]phthalazine-5,8-dione; bpy = 2,2‧-bipyridine) 3, as well as two acylhydrazide molecules L4 (L4 = oxepino[2,3,4-de:7,6,5-d‧e‧]diphthalazine-4,10(5H,9H)-dione) 4 and L5 (L5 = 4,5-dibromophthalhydrazide; L5 = 6,7-dibromo-2,3-dihydrophthalazine-1,4-dione) 5 were obtained. X-ray single-crystal diffraction analysis reveals that (i) 1 only possesses a mononuclear structure, but it self-assembles into a 2-D supramolecular network via the Nhydrazinesbnd H ⋯ Nhydrazine and Owsbnd H ⋯ Ohydroxylimino interactions; (ii) 2 exhibits a dinuclear structure. Ox acts as the linker, while L2 just serves as a terminal ligand; (iii) In 3, L3 acts as a 3-connected node to propagate the 7-coordinated Cd2 + centers into a 1-D double-chain structure; (iv) 4 is a special acylhydrazide molecule. Two sbnd OH groups for the intermediates 3,3‧-biphthalhydrazide further lose one water molecule to form 4; (v) 5 is a common monoacylhydrazide molecule. Via the Nhydrazinesbnd H ⋯ Ohydrazine, Ohydroxyliminosbnd H ⋯ Oacylamino and the π ⋯ π interactions, it self-assembles into a 2-D supramolecular network. The photoluminescence analysis reveals that 4 emits light with the maxima at 510 nm.

  3. Using low-frequency IR spectra for the unambiguous identification of metal ion-ligand coordination sites in purpose-built complexes.

    Science.gov (United States)

    Varga, Gábor; Csendes, Zita; Peintler, Gábor; Berkesi, Ottó; Sipos, Pál; Pálinkó, István

    2014-03-25

    One of the aims of our long-term research is the identification of metal ion-ligand coordination sites in bioinspired metal ion-C- or N-protected amino acid (histidine, tyrosine, cysteine or cystine) complexes immobilised on the surface of chloropropylated silica gel or Merrifield resin. In an attempt to reach this goal, structurally related, but much simpler complexes have been prepared and their metal ion-ligand vibrations were determined from their low-frequency IR spectra. The central ions were Mn(II), Co(II), Ni(II) or Cu(II) and the ligands (imidazole, isopropylamine, monosodium malonate) were chosen to possess only one-type of potential donor group. The low-frequency IR spectra were taken of the complexes for each ion-ligand combination and the typical metal ion-functional group vibration bands were selected and identified. The usefulness of the obtained assignments is demonstrated on exemplary immobilised metal ion-protected amino acid complexes.

  4. Characterization of the TolB-Pal trans-envelope complex from Xylella fastidiosa reveals a dynamic and coordinated protein expression profile during the biofilm development process.

    Science.gov (United States)

    Santos, Clelton A; Janissen, Richard; Toledo, Marcelo A S; Beloti, Lilian L; Azzoni, Adriano R; Cotta, Monica A; Souza, Anete P

    2015-10-01

    The intriguing roles of the bacterial Tol-Pal trans-envelope protein complex range from maintenance of cell envelope integrity to potential participation in the process of cell division. In this study, we report the characterization of the XfTolB and XfPal proteins of the Tol-Pal complex of Xylella fastidiosa. X. fastidiosa is a major plant pathogen that forms biofilms inside xylem vessels, triggering the development of diseases in important cultivable plants around the word. Based on functional complementation experiments in Escherichia coli tolB and pal mutant strains, we confirmed the role of xftolB and xfpal in outer membrane integrity. In addition, we observed a dynamic and coordinated protein expression profile during the X. fastidiosa biofilm development process. Using small-angle X-ray scattering (SAXS), the low-resolution structure of the isolated XfTolB-XfPal complex in solution was solved for the first time. Finally, the localization of the XfTolB and XfPal polar ends was visualized via immunofluorescence labeling in vivo during bacterial cell growth. Our results highlight the major role of the components of the cell envelope, particularly the TolB-Pal complex, during the different phases of bacterial biofilm development. PMID:26049080

  5. Coordination diversity in mono- and oligonuclear copper(II) complexes of pyridine-2-hydroxamic and pyridine-2,6-dihydroxamic acids.

    Science.gov (United States)

    Gumienna-Kontecka, Elzbieta; Golenya, Irina A; Szebesczyk, Agnieszka; Haukka, Matti; Krämer, Roland; Fritsky, Igor O

    2013-07-01

    Solution and solid state studies on Cu(II) complexes of pyridine-2-hydroxamic acid (HPicHA) and pyridine-2,6-dihydroxamic acid (H2PyDHA) were carried out. The use of methanol/water solvent allowed us to investigate the Cu(II)-HPicHA equilibria under homogeneous conditions between pH 1 and 11. In agreement with ESI-MS indication, the potentiometric data fitted very well with the model usually reported for copper(II) complexes of α-aminohydroxamate complexes ([CuL](+), [Cu5(LH-1)4](2+), [CuL2], [CuL2H-1](-)), however with much higher stability of the 12-MC-4 species. A series of copper(II) complexes has been isolated in the solid state and characterized by a variety of spectroscopic methods, X-ray structure analysis, and magnetic susceptibility measurements. The ligands show the tendency to form bi- and trinuclear species with copper(II) ions due to the {(N,N'); (O,O')} bis-(bidentate) chelating-and-bridging mode involving (O,O')-hydroxamate chelate formation combined with (N,N') chelating with participation of the pyridine and hydroxamic nitrogen atoms, so that the hydroxamate groups play a μ2-(N,O)-bridging role. Molecular and crystal structures of three synthesized complexes [Cu3(PicHA-H)2(dipy)2](ClO4)2·4/3DMSO·2/3H2O (1), [Cu2(PyDHA)(dipy)2(ClO4)2]·DMF·H2O (4), and [Cu3(PyDHA-2H)(tmeda)3](ClO4)2 (5) (dipy, 2,2'-dipyridyl; tmeda, N,N,N',N'-tetramethyl-1,2-diaminoethane) have been determined by single crystal X-ray analysis. In 1, two trans-situated doubly deprotonated hydroxamic ligands play a {(O,O')(N,N')}-(bis)bidentate-bridging function forming bridges between the medial, Cu(2) (CuN4), and the terminal, Cu(1) and Cu(3) (CuN2O2), copper(II) ions; the chelating dipy ligands are coordinated to the latter. In 4, the ligand is coordinated in a classical (O,O')-hydroxamate chelating mode with the help of two separate hydroxamic groups while the central tridentate donor compartment remains vacant. In 5, the hydroxamate ligand is coordinated by the {(O

  6. Competitive coordination aggregation for V-shaped [Co3] and disc-like [Co7] complexes: synthesis, magnetic properties and catechol oxidase activity.

    Science.gov (United States)

    Singha Mahapatra, Tufan; Basak, Dipmalya; Chand, Santanu; Lengyel, Jeff; Shatruk, Michael; Bertolasi, Valerio; Ray, Debashis

    2016-09-14

    Unique dependence on the nature of metal salt and reaction conditions for coordination assembly reactions of varying architecture and nuclearity have been identified in V-shaped [Co3L4] and planar disc-like [Co7L6] compounds: [CoL2(μ-L)2(μ-OH2)2(CF3CO2)2] (1) and [Co(μ-L)6(μ-OMe)6]Cl2 (2) (HL = 2-{(3-ethoxypropylimino)methyl}-6-methoxyphenol). At room temperature varying reaction conditions, cobalt-ligand ratios and use of different bases allowed unique types of coordination self-assembly. The synthetic marvel lies in the nature of aggregation with respect to the two unrelated cores in 1 and 2. Complex 1 assumes a V-shaped arrangement bound to L(-), water and a trifluoroacetate anion, while 2 grows around a central Co(II) ion surrounded by a {Co} hexagon bound to methoxide and L(-). Magnetic measurements revealed that the intermetallic interactions are antiferromagnetic in nature in the case of complex 1 and ferromagnetic in the case of 2 involving high spin cobalt(ii) ions with stabilization of the high-spin ground state in the latter case. In MeCN solutions complexes 1 and 2 showed catalytic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCH2) to 3,5-di-tert-butylbenzoquinone (3,5-DTBQ) in air. The kinetic study in MeCN revealed that with respect to the catalytic turnover number (kcat) 2 is more effective than 1 for oxidation of 3,5-DTBCH2. PMID:27510847

  7. Coordinating Work with Groupware

    DEFF Research Database (Denmark)

    Pors, Jens Kaaber; Simonsen, Jesper

    2003-01-01

    One important goal of employing groupware is to make possible complex collaboration between geographically distributed groups. This requires a dual transformation of both technology and work practice. The challenge is to re­duce the complexity of the coordination work by successfully inte....... Using the CSCW frame­work of coordination mechanisms, we have elicited six general factors influencing the integration of the groupware application in two situations....

  8. Exploring new avenues for Arene-Ruthenium complexes: coordination to [60]fullerene, hydrogen bonding assemblies and liquid-crystalline materials

    OpenAIRE

    Appavoo-Gupta, Divambal; Deschenaux, Robert

    2016-01-01

    The thesis aims at using arene-ruthenium complexes as building blocks for the synthesis of diverse compounds to obtain potential mesomorphic and/or biological properties. The thesis consists of three main projects. The first project deals with supramolecular assemblies. New supramolecular di- and tetranuclear ruthenium arrangements, the latter bearing a cavity, were designed. H-bonding was the key interaction involved in the synthesis of the spacer ligands, which exist as dimers. Different s...

  9. Fluorescent sensing and electrocatalytic properties of three Zn(II)/Co(II) coordination complexes containing two different dicarboxylates and two various bis(pyridyl)-bis(amide) ligands

    Science.gov (United States)

    Lin, Hongyan; Rong, Xing; Liu, Guocheng; Wang, Xiang; Wang, Xiuli; Duan, Surui

    2016-09-01

    Three new transition metal(II) coordination complexes constructed from two different dicarboxylates (1,3-H2BDC = 1,3-benzenedicarboxylic acid, 1,4-H2NDC = 1,4-naphthalenedicarboxylic acid) and two bis(pyridyl)-bis(amide) ligands (3-bpcd = N,N‧-bis(3-pyridyl)cyclohexane-1,4-dicarboxamide, 3-bpod = N,N‧-bis(3-pyridyl)octandiamide), [Zn(1,3-BDC)(3-bpcd)0.5(H2O)]·H2O (1), [Zn(1,3-BDC)(3-bpod)0.5(H2O)] (2) and [Co(1,4-NDC)(3-bpod)1.5(H2O)] (3) have been synthesized in the hydrothermal environments and structurally characterized by IR, TG and single crystal X-ray diffraction. Complexes 1 and 2 possess the similar 1D ladder-like chain based on [Zn(1,3-BDC)]n zigzag chain and the bidentate ligands 3-bpcd/or 3-bpod. Complex 3 shows a 2D layered structure with a 5-connected {410} topology, which consists of 1D linear [Co(1,4-NDC)]n chain and [Co(3-bpod)1.5]n chain with alternating arrangement of 3-bpod ligands and Co2(3-bpod)2 dinuclear loops. The adjacent 1D chains for 1-2 or the 2D layers for 3 are further extended into 2D or 3D supramolecular frameworks through the hydrogen bonding interactions. Additionally, the solid state fluorescent properties for the title complexes 1-3, the fluorescent sensing behaviors of complexes 1-2 and the electrochemical behaviour of complex 3 have been investigated.

  10. Computational insight into complex structures of thorium coordination with N, N'- bis(3-allyl salicylidene)-o-phenylenediamine.

    Science.gov (United States)

    Lan, Wenbo; Gao, Sha; Lin, Ying-Wu; Liao, Lifu; Wang, Xiaofeng; Nie, Changming

    2016-09-01

    Theoretical calculations on the structure of Th(IV) complex containing N, N'- bis(3-allyl salicylidene)-o-phenylenediamine (BASPDA) were performed using density functional theory (DFT) at the B3LYP/6-311G** level. The geometrical structural parameters and infrared spectra results of the Th(BASPDA)2 from the calculation were compared with the parallel dislocated structure (PDS) obtained in laboratory. The calculated structural parameters were in good agreement with the experimental results. In addition, based on the calculations, a stereoisomer SFS (staggered finger " + " structure) of the Th(BASPDA)2 complex was forecasted by the analysis of a comprehensive method. The charge distribution, structural parameters, bond order indices, spectral properties and thermodynamic properties as well as the molecular orbitals of the two possible crystal structures of Th(BASPDA)2 were also systematically studied. It was expected that this work could provide insightful information for understanding the properties of Th (BASPDA)2 complex at the molecular level.

  11. Coordination equilibria in the complex formation of guanylurea with CuII: Formation and stability of binary CuII-guanylurea and ternary CuII-guanylurea-glycinate complexes

    Indian Academy of Sciences (India)

    Tannistha Roy Barman; G N Mukherjee

    2008-07-01

    Combined pH-metric and spectrophotometric investigations on the complex formation equilibria of CuII with guanylurea (H$_{2}^{1}$NC(=O) 2NH.C(=3NH) 4NH2), hereafter, GuH, in the absence and in the presence of glycine (GlyH), in aqueous solution indicates variety of binary and mixed-ligand complexes: Cu(Gu)+, Cu(Gu)(OH); Cu(Gu)2, Cu(Gu-H)(Gu)-, Cu(Gu-H)$_{2}^{2-}$, Cu(Gu-H)(Gu-2H)3-; Cu(Gly)+, Cu(Gly) (OH); Cu(Gly)(Gu); Cu(Gly)(Gu-H)-, Cu(Gly)(Gu-2H)2-; (Gly)Cu(Gu)Cu(Gly)+, (Gly)Cu(Gu-H)Cu(Gly) and (Gly)Cu(Gu-2H)Cu(Gly)-. At pH < 6, guanylurea anion (Gu-) acts as a [(C=O), 3N-] or [=1NH, 3N-] bidentate ligand and above pH 7 it is transformed through a coordination equilibrium into a (=1N-, =3N-) bidentate ligand, similar to biguanide dianion. Occurrence of dinuclear complex species, (Gly) Cu(Gu)Cu(Gly)+, in the complexation equilibria, indicates bridging double bidentate [(1NH2, 3N-), (C=O, 4NH2)] and/or [(1NH2, 4NH2), (C=O, 3N-)] chelation by Gu- ion in an isomeric equilibrium. Above pH 6.5, the dinuclear complex decomposes mostly to the mononuclear species, Cu(Gly)(OH) and Cu(Gu)(OH) and only partly deprotonates to (Gly)Cu(Gu-H)Cu(Gly) and (Gly)Cu(Gu-2H)Cu(Gly)-. Electronic spectral shifts, with change of pH have been correlated with the possible modes of coordination of guanylurea species.

  12. Anion-Directed Copper(II) Metallocages, Coordination Chain, and Complex Double Salt: Structures, Magnetic Properties, EPR Spectra, and Density Functional Study.

    Science.gov (United States)

    Wu, Jing-Yun; Zhong, Ming-Shiou; Chiang, Ming-Hsi; Bhattacharya, Dibyendu; Lee, Yen-Wei; Lai, Long-Li

    2016-05-17

    A series of Cu(II) metallo-assemblies showing anion-directed structural variations, including five metallocages [(G(n-) )⊂{Cu2 (Hdpma)4 }]((8-n)+) (A(-) )8-n (G(n-) =NO3 (-) , ClO4 (-) , SiF6 (2-) , BF4 (-) , SO4 (2-) ; A(-) =NO3 (-) , ClO4 (-) , BF4 (-) , CH3 SO4 (-) ; Hdpma=bis(3-pyridylmethyl)ammonium cation), a complex double salt, namely, (H3 dpma)4 (CuCl4 )5 Cl2 , and a coordination chain, namely, [Cu2 (dpma)(OAc)4 ], are reported. The influence of the anion can be explained by its coordinating ability, the affinity of which for the Cu(II) center interferes significantly with metallocage formation, and its shape, which offers host-guest recognition ability to engage in weak metal-anion coordination and hydrogen bonding to the organic ligand, which are responsible for metallocage templation. EPR studies of these metallocages in the powder phase at room temperature and 77 K showed a trend of the g values (g|| >2.10>g⊥ >2.00) indicating a dx2-y2 -based ground state with square-pyramidal geometry for the Cu(II) centers. The magnetism of these metallocages can be interpreted as the result of a combination of relatively small magnetic coupling integrals and a substantial contribution of temperature-independent paramagnetism (TIP). The weak magnetic interaction is corroborated by the results of DFT calculations and the EPR spectra. Availability of the low-lying state for spin population was confirmed by a magnetization study, which revealed a magnetic moment approaching 2Nβ, which would explain the presence of the larger TIP term.

  13. Coordinated regulation of the ESCRT-III component CHMP4C by the chromosomal passenger complex and centralspindlin during cytokinesis

    Science.gov (United States)

    Capalbo, Luisa; Mela, Ioanna; Abad, Maria Alba; Jeyaprakash, A. Arockia; Edwardson, J. Michael

    2016-01-01

    The chromosomal passenger complex (CPC)—composed of Aurora B kinase, Borealin, Survivin and INCENP—surveys the fidelity of genome segregation throughout cell division. The CPC has been proposed to prevent polyploidy by controlling the final separation (known as abscission) of the two daughter cells via regulation of the ESCRT-III CHMP4C component. The molecular details are, however, still unclear. Using atomic force microscopy, we show that CHMP4C binds to and remodels membranes in vitro. Borealin prevents the association of CHMP4C with membranes, whereas Aurora B interferes with CHMP4C's membrane remodelling activity. Moreover, we show that CHMP4C phosphorylation is not required for its assembly into spiral filaments at the abscission site and that two distinctly localized pools of phosphorylated CHMP4C exist during cytokinesis. We also characterized the CHMP4C interactome in telophase cells and show that the centralspindlin complex associates preferentially with unphosphorylated CHMP4C in cytokinesis. Our findings indicate that gradual dephosphorylation of CHMP4C triggers a ‘relay’ mechanism between the CPC and centralspindlin that regulates the timely distribution and activation of CHMP4C for the execution of abscission. PMID:27784789

  14. Novel bipyridinyl oxadiazole-based metal coordination complexes: High efficient and green synthesis of 3,4-dihydropyrimidin-2(1H)-ones through the Biginelli reactions

    Science.gov (United States)

    Wang, Jin-Hua; Zhang, E.; Tang, Gui-Mei; Wang, Yong-Tao; Cui, Yue-Zhi; Ng, Seik Weng

    2016-09-01

    Three new metal coordination complexes, namely, [Co(BPO)2(H2O)4](BS)2(H2O)2 (1), [Co(BPO)2(H2O)4](ABS)2(H2O)2 (2), [Co(BPO)2(H2O)4](MBS)2(H2O)2 (3) [BPO=2,5-di(pyridin-4-yl)-1,3,4-oxadiazole, BS=benzenesulphonate, ABS=4-aminobenzenesulphonate, MBS=4-methylbenzenesulphonate] were obtained under hydrothermal conditions. Complexes 1-3 were structurally characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR and thermogravimetric analyses (TGA). All of them display a zero-dimensional motif, in which strong intermolecular hydrogen bonding interactions (O-H···O/N) and packing interactions (C-H···π and π···π) make them achieve a three-dimensional supramolecular architecture. The primary catalytic results of these three complexes show that high efficiency for the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones was observed under solvent free conditions through Biginelli reactions. The present catalytic protocols exhibit advantages such as excellent yield, easy isolation, eco-friendly conditions, and short reaction time.

  15. Open coordination sites-induced structural diversity of a new series of Cu(II) complexes with tridentate aroylhydrazone Schiff base

    Science.gov (United States)

    Xu, Guohong; Tang, Beibei; Gu, Leilei; Zhou, Pei; Li, Hui

    2016-09-01

    Six Cu(II) complexes containing the NO2 donor tridentate asymmetrical aroylhydrazone ligand (E)-4-hydroxy-N‧-((2-hydroxynaphthalen-1-yl)methylene)benzohydrazide (HL), namely, [Cu(L)Cl]·2H2O (1), [Cu(L)(CH3OH)2]·NO3 (2), [Cu(L)(NO3)(H2O)]·H2O (3), [Cu(L)(CH3OH)Cl]·CH3OH (4), [Cu(L)(SCN)(DMF)]·DMF (5) and {[Cu(L)(4,4‧-bipy)]ClO4·4DMF}n (6) have been synthesized and analysized by X-ray singal crystal diffraction. The structures of 1-6 are varied from zero-dimensional (0D) mononuclear complex to one-dimensional (1D) polymer based on the control of solvents, anions or auxiliary ligands, which can occupy the open coordination sites of Cu(II). Different hydrogen bonding interactions can also be observed in these complexes.

  16. Synthesis, crystal structures and coordination modes of some triorganotin(IV) complexes with 2-N-propyl and 2-N-benzyl-amino-1-cyclopentene-1-dithiocarboxylates

    Science.gov (United States)

    López-Cardoso, Marcela; Vargas-Pineda, Gabriela; Román-Bravo, Perla Patricia; Rodríguez-Narváez, Cristina; Rosas-Valdez, Elena; Cea-Olivares, Raymundo

    2016-07-01

    The syntheses and characterization of six new triorganotin(IV) complexes, Ph3Sn(PrACDA) (1), Bu3Sn(PrACDA) (2), Ph3Sn(BzACDA) (3), Bu3Sn(BzACDA) (4), Me3Sn(BzACDA) (5) and Cy3Sn(BzACDA) (6) (ACDA = 2-amino-1-cyclopentene-1-carbodithioate anion) are reported. Compounds 1-6 were synthesized by the reaction between the sodium salts of 2-N-propyl- or 2-N-benzyl-2-amino-1-cyclopentene-1-carbodithioate and R3SnCl (R = Ph, Bu, Me, Cy) in a 1:1 M ratio. The complexes were characterized by elemental analyses, IR and NMR (1H, 13C and 119Sn) spectroscopy and by FAB+ mass spectrometry. The experimental data reveal that the tin atom is coordinated to the ligand by means of the two sulfur atoms from the carbodithioate group in an anisobidentate mode, while the 119Sn{1H} NMR spectra suggest a pentacoordinate metal center in 1-4 and a tetracoordinate tin atom for 5 and 6. The molecular structures of complexes 1, 3 and 5 were confirmed by single crystal X-ray diffraction analysis showing the presence of N-H···S hydrogen bonding and a distorted trigonal bipyramid geometry for the tin atoms.

  17. Complexation of curium(III) with DTPA at 10-70 °C: comparison with Eu(III)-DTPA in thermodynamics, luminescence, and coordination modes.

    Science.gov (United States)

    Tian, Guoxin; Zhang, Zhiyong; Martin, Leigh R; Rao, Linfeng

    2015-02-16

    Separation of trivalent actinides (An(III)) from trivalent lanthanides (Ln(III)) is a challenging task because of the nearly identical chemical properties of these groups. Diethylenetriaminepentaacetate (DTPA), a key reagent used in the TALSPEAK process that effectively separates An(III) from Ln(III), is believed to play a critical role in the An(III)/Ln(III) separation. However, the underlying principles for the separation based on the difference in the complexation of DTPA with An(III) and Ln(III) remain unclear. In this work, the complexation of DTPA with Cm(III) at 10-70 °C was investigated by spectrophotometry, luminescence spectroscopy, and microcalorimetry, in conjunction with computational methods. The binding strength, the enthalpy of complexation, the coordination modes, and the luminescence properties are compared between the Cm(III)-DTPA and Eu(III)-DTPA systems. The experimental and computational data demonstrated that the difference between Cm(III) and Eu(III) in the binding strength with DTPA can be attributed to the stronger covalence bonding between Cm(III) and the nitrogen donors of DTPA.

  18. Designed Single-Step Synthesis, Structure, and Derivative Textural Properties of Well-Ordered Layered Penta-coordinate Silicon Alcoholate Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Li, XS; Michaelis, VK; Ong, TC; Smith, SJ; Griffin, RG; Wang, EN

    2014-04-15

    The controllable synthesis of well-ordered layered materials with specific nanoarchitecture poses a grand challenge in materials chemistry. Here the solvothermal synthesis of two structurally analogous 5-coordinate organosilicate complexes through a novel transesterification mechanism is reported. Since the polycrystalline nature of the intrinsic hypervalent Si complex thwarts the endeavor in determining its structure, a novel strategy concerning the elegant addition of a small fraction of B species as an effective crystal growth mediator and a sacrificial agent is proposed to directly prepare diffraction-quality single crystals without disrupting the intrinsic elemental type. In the determined crystal structure, two monomeric primary building units (PBUs) self-assemble into a dimeric asymmetric secondary BU via strong Na+O2- ionic bonds. The designed one-pot synthesis is straightforward, robust, and efficient, leading to a well-ordered (10)-parallel layered Si complex with its principal interlayers intercalated with extensive van der Waals gaps in spite of the presence of substantial Na+ counter-ions as a result of unique atomic arrangement in its structure. However, upon fast pyrolysis, followed by acid leaching, both complexes are converted into two SiO2 composites bearing BET surface areas of 163.3 and 254.7m(2)g(-1) for the pyrolyzed intrinsic and B-assisted Si complexes, respectively. The transesterification methodology merely involving alcoholysis but without any hydrolysis side reaction is designed to have generalized applicability for use in synthesizing new layered metal-organic compounds with tailored PBUs and corresponding metal oxide particles with hierarchical porosity.

  19. 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.

  20. DFT 2H quadrupolar coupling constants of ruthenium complexes: a good probe of the coordination of hydrides in conjuction with experiments.

    Science.gov (United States)

    del Rosal, Iker; Gutmann, Torsten; Maron, Laurent; Jolibois, Franck; Chaudret, Bruno; Walaszek, Bernadeta; Limbach, Hans-Heinrich; Poteau, Romuald; Buntkowsky, Gerd

    2009-07-21

    Transition metal (TM) hydrides are of great interest in chemistry because of their reactivity and their potential as catalysts for hydrogenation reactions. 2H solid-state NMR can be used in order to get information about the local environment of hydrogen atoms, and more particularly the coordination mode of hydrides in such complexes. In this work we will show that it is possible to establish at the level of density functional theory (DFT) a viable methodological strategy that allows the determination of 2H NMR parameters, namely the quadrupolar coupling constant (C(Q)) respectively the quadrupolar splitting (deltanuQ) and the asymmetry parameter (etaQ). The reliability of the method (B3PW91-DFT) and basis set effects have been first evaluated for simple organic compounds (benzene and fluorene). A good correlation between experimental and theoretical values is systematically obtained if the large basis set cc-pVTZ is used for the computations. 2H NMR properties of five mononuclear ruthenium complexes (namely Cp*RuD3(PPh3), Tp*RuD(THT)2, Tp*RuD(D2)(THT) and Tp*RuD(D2)2 and RuD2(D2)2(PCy3)2) which exhibit different ligands and hydrides involved in different coordination modes (terminal-H or eta2-H2), have been calculated and compared to previous experimental data. The results obtained are in excellent agreement with experiments. Although 2H NMR spectra are not always easy to analyze, assistance by quantum chemistry calculations allows unambiguous assignment of the signals of such spectra. As far as experiments can be achieved at very low temperatures in order to avoid dynamic effects, this hybrid theoretical/experimental tool may give useful insights in the context of the characterization of ruthenium surfaces or nanoparticles with solid-state NMR. PMID:19842483

  1. Influence of the π-coordinated arene on the anticancer activity of ruthenium(II carbohydrate organometallic complexes

    Directory of Open Access Journals (Sweden)

    Muhammad eHanif

    2013-10-01

    Full Text Available The synthesis and in vitro cytotoxicity of a series of RuII(arene complexes with carbohydrate-derived phosphite ligands and various arene co-ligands is described. The arene ligand has a strong influence on the in vitro anticancer activity of this series of compounds, which correlates fairly well with cellular accumulation. The most lipophilic compound bearing a biphenyl moiety and a cyclohexylidene-protected carbohydrate is the most cytotoxic with unprecedented IC50 values for the compound class in three human cancer cell lines. This compound shows reactivity to the DNA model nucleobase 9-ethylguanine, but does not alter the secondary structure of plasmid DNA indicating that other biological targets are responsible for its cytotoxic effect.

  2. Coordination Compounds of Niobium(IV) Oxide Dihalides Including the Synthesis and the Crystallographic Characterization of NHC Complexes.

    Science.gov (United States)

    Bortoluzzi, Marco; Ferretti, Eleonora; Marchetti, Fabio; Pampaloni, Guido; Pinzino, Calogero; Zacchini, Stefano

    2016-05-01

    The 1:1 molar reactions of NbOX3 with SnBu3H, in toluene at 0 °C in the presence of oxygen/nitrogen donors, resulted in the formation of NbOX2L2 (X = Cl, L2 = dme, 2a; X = Br, L2 = dme, 2b; X = Cl, L = thf, 2c; X = Cl, L = NCMe, 2d; dme = 1,2-dimethoxyethane, thf = tetrahydrofuran), in good yields. The 1:2 reactions of freshly prepared 2d and 2b with the bulky NHC ligands 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, Imes, and 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene, Ixyl, respectively, afforded the complexes NbOCl2(Imes)2, 3, and NbOBr2(Ixyl)2, 4, in 50-60% yields. The reactions of 2b with NaOR, in tetrahydrofuran, gave NbOCl(OR) (R = Ph, 5; R = Me, 6) in about 60% yields. All the products were characterized by analytical and spectroscopic techniques; moreover DFT calculations were carried out in order to shed light on synthetic and structural features. Compounds 3 and 4, whose molecular structures have been ascertained by X-ray diffraction, represent very rare examples of crystallographically characterized niobium-NHC systems.

  3. A series of novel 1D coordination polymers constructed from metal?quinolone complex fragments linked by aromatic dicarboxylate ligands

    Science.gov (United States)

    He, Jiang-Hong; Xiao, Dong-Rong; Yan, Shi-Wei; Sun, Dian-Zhen; Chen, Hai-Yan; Wang, Xin; Yang, Juan; Ye, Zhong-Li; Yuan, Ruo; Wang, En-Bo

    2012-08-01

    Self-assembly of quinolones with metal salts in the presence of aromatic dicarboxylate ligands affords a series of novel 1D metal-quinolone complexes, namely [Mn(Hppa)(oba)]·3H2O (1), [Co(Hppa)(oba)]·3.25H2O (2), [Zn(Hppa)(sdba)]·1.5H2O (3), [Mn(Hcf)(bpda)(H2O)]·2H2O (4), [Mn(Hppa)2(bpdc)] (5) and [Mn(Hlome)2(bpdc)]·4H2O (6) (Hppa = Pipemidic acid, Hcf = ciprofloxacin, Hlome = lomefloxacin). The structures of compounds 1-3 consist of novel polymeric chains spanning two different directions, which display an intriguing 1D → 3D inclined polycatenation of supramolecular ladders. Compound 4 exhibits a chain compound formed from the interconnection of [Mn2(Hcf)2(μ-CO2)2] dimers with bpda ligands. Compounds 5 and 6 are similar chain compounds constructed from [Mn(Hppa)2] (or [Mn(Hlome)2]) fragments linked by bpdc ligands. The magnetic properties of 4 have been studied, which indicate the existence of antiferromagnetic interactions. Furthermore, the luminescent properties of compound 3 are discussed.

  4. Coordinated destruction of cellular messages in translation complexes by the gammaherpesvirus host shutoff factor and the mammalian exonuclease Xrn1.

    Science.gov (United States)

    Covarrubias, Sergio; Gaglia, Marta M; Kumar, G Renuka; Wong, Wesley; Jackson, Andrew O; Glaunsinger, Britt A

    2011-10-01

    Several viruses encode factors that promote host mRNA degradation to silence gene expression. It is unclear, however, whether cellular mRNA turnover pathways are engaged to assist in this process. In Kaposi's sarcoma-associated herpesvirus this phenotype is enacted by the host shutoff factor SOX. Here we show that SOX-induced mRNA turnover is a two-step process, in which mRNAs are first cleaved internally by SOX itself then degraded by the cellular exonuclease Xrn1. SOX therefore bypasses the regulatory steps of deadenylation and decapping normally required for Xrn1 activation. SOX is likely recruited to translating mRNAs, as it cosediments with translation initiation complexes and depletes polysomes. Cleaved mRNA intermediates accumulate in the 40S fraction, indicating that recognition occurs at an early stage of translation. This is the first example of a viral protein commandeering cellular mRNA turnover pathways to destroy host mRNAs, and suggests that Xrn1 is poised to deplete messages undergoing translation in mammalian cells.

  5. Coordinated destruction of cellular messages in translation complexes by the gammaherpesvirus host shutoff factor and the mammalian exonuclease Xrn1.

    Directory of Open Access Journals (Sweden)

    Sergio Covarrubias

    2011-10-01

    Full Text Available Several viruses encode factors that promote host mRNA degradation to silence gene expression. It is unclear, however, whether cellular mRNA turnover pathways are engaged to assist in this process. In Kaposi's sarcoma-associated herpesvirus this phenotype is enacted by the host shutoff factor SOX. Here we show that SOX-induced mRNA turnover is a two-step process, in which mRNAs are first cleaved internally by SOX itself then degraded by the cellular exonuclease Xrn1. SOX therefore bypasses the regulatory steps of deadenylation and decapping normally required for Xrn1 activation. SOX is likely recruited to translating mRNAs, as it cosediments with translation initiation complexes and depletes polysomes. Cleaved mRNA intermediates accumulate in the 40S fraction, indicating that recognition occurs at an early stage of translation. This is the first example of a viral protein commandeering cellular mRNA turnover pathways to destroy host mRNAs, and suggests that Xrn1 is poised to deplete messages undergoing translation in mammalian cells.

  6. Coordination Compounds of Niobium(IV) Oxide Dihalides Including the Synthesis and the Crystallographic Characterization of NHC Complexes.

    Science.gov (United States)

    Bortoluzzi, Marco; Ferretti, Eleonora; Marchetti, Fabio; Pampaloni, Guido; Pinzino, Calogero; Zacchini, Stefano

    2016-05-01

    The 1:1 molar reactions of NbOX3 with SnBu3H, in toluene at 0 °C in the presence of oxygen/nitrogen donors, resulted in the formation of NbOX2L2 (X = Cl, L2 = dme, 2a; X = Br, L2 = dme, 2b; X = Cl, L = thf, 2c; X = Cl, L = NCMe, 2d; dme = 1,2-dimethoxyethane, thf = tetrahydrofuran), in good yields. The 1:2 reactions of freshly prepared 2d and 2b with the bulky NHC ligands 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, Imes, and 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene, Ixyl, respectively, afforded the complexes NbOCl2(Imes)2, 3, and NbOBr2(Ixyl)2, 4, in 50-60% yields. The reactions of 2b with NaOR, in tetrahydrofuran, gave NbOCl(OR) (R = Ph, 5; R = Me, 6) in about 60% yields. All the products were characterized by analytical and spectroscopic techniques; moreover DFT calculations were carried out in order to shed light on synthetic and structural features. Compounds 3 and 4, whose molecular structures have been ascertained by X-ray diffraction, represent very rare examples of crystallographically characterized niobium-NHC systems. PMID:27082642

  7. Coordination and processing of DNA ends during double-strand break repair: the role of the bacteriophage T4 Mre11/Rad50 (MR) complex.

    Science.gov (United States)

    Almond, Joshua R; Stohr, Bradley A; Panigrahi, Anil K; Albrecht, Dustin W; Nelson, Scott W; Kreuzer, Kenneth N

    2013-11-01

    The in vivo functions of the bacteriophage T4 Mre11/Rad50 (MR) complex (gp46/47) in double-strand-end processing, double-strand break repair, and recombination-dependent replication were investigated. The complex is essential for T4 growth, but we wanted to investigate the in vivo function during productive infections. We therefore generated a suppressed triple amber mutant in the Rad50 subunit to substantially reduce the level of complex and thereby reduce phage growth. Growth-limiting amounts of the complex caused a concordant decrease in phage genomic recombination-dependent replication. However, the efficiencies of double-strand break repair and of plasmid-based recombination-dependent replication remained relatively normal. Genetic analyses of linked markers indicated that double-strand ends were less protected from nuclease erosion in the depleted infection and also that end coordination during repair was compromised. We discuss models for why phage genomic recombination-dependent replication is more dependent on Mre11/Rad50 levels when compared to plasmid recombination-dependent replication. We also tested the importance of the conserved histidine residue in nuclease motif I of the T4 Mre11 protein. Substitution with multiple different amino acids (including serine) failed to support phage growth, completely blocked plasmid recombination-dependent replication, and led to the stabilization of double-strand ends. We also constructed and expressed an Mre11 mutant protein with the conserved histidine changed to serine. The mutant protein was found to be completely defective for nuclease activities, but retained the ability to bind the Rad50 subunit and double-stranded DNA. These results indicate that the nuclease activity of Mre11 is critical for phage growth and recombination-dependent replication during T4 infections.

  8. Electronic structure of four-coordinate C3v nickel(II) scorpionate complexes: investigation by high-frequency and -field electron paramagnetic resonance and electronic absorption spectroscopies.

    Science.gov (United States)

    Desrochers, Patrick J; Telser, Joshua; Zvyagin, S A; Ozarowski, Andrew; Krzystek, J; Vicic, David A

    2006-10-30

    A series of complexes of formula TpNiX, where Tp*- = hydrotris(3,5-dimethylpyrazole)borate and X = Cl, Br, I, has been characterized by electronic absorption spectroscopy in the visible and near-infrared (NIR) region and by high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy. The crystal structure of TpNiCl has been previously reported; that for TpNiBr is given here: space group = Pmc2(1), a = 13.209(2) A, b = 8.082(2) A, c = 17.639(4) A, alpha = beta = gamma = 90 degrees , Z = 4. TpNiX contains a four-coordinate nickel(II) ion (3d8) with approximate C3v point group symmetry about the metal and a resulting S = 1 high-spin ground state. As a consequence of sizable zero-field splitting (zfs), TpNiX complexes are "EPR silent" with use of conventional EPR; however, HFEPR allows observation of multiple transitions. Analysis of the resonance field versus the frequency dependence of these transitions allows extraction of the full set of spin Hamiltonian parameters. The axial zfs parameter for TpNiX displays pronounced halogen contributions down the series: D = +3.93(2), -11.43(3), -22.81(1) cm(-1), for X = Cl, Br, I, respectively. The magnitude and change in sign of D observed for TpNiX reflects the increasing bromine and iodine spin-orbit contributions facilitated by strong covalent interactions with nickel(II). These spin Hamiltonian parameters are combined with estimates of 3d energy levels based on the visible-NIR spectra to yield ligand-field parameters for these complexes following the angular overlap model (AOM). This description of electronic structure and bonding in a pseudotetrahedral nickel(II) complex can enhance the understanding of similar sites in metalloproteins, both native nickel enzymes and nickel-substituted zinc enzymes. PMID:17054352

  9. Redox non-innocence of coordinated 2-(arylazo) pyridines in iridium complexes: characterization of redox series and an insight into voltage-induced current characteristics.

    Science.gov (United States)

    Goswami, Sreetosh; Sengupta, Debabrata; Paul, Nanda D; Mondal, Tapan K; Goswami, Sreebrata

    2014-05-12

    Two examples of a rare class of di-radical azo-anion complexes of 2-(arylazo) pyridine with Ir(III) carrier are introduced. Their electronic structures have been elucidated using a host of physical methods that include X-ray crystallography, cyclic voltammetry, electron paramagnetic resonance spectroscopy, and density functional theory. Room temperature magnetic moments of these are consistent with two nearly non-interacting azo-anion radicals. These displayed rich electrochemical properties consisting of six numbers of reversible and successive one electron CV-waves. Redox processes occur entirely at the coordinated ligands without affecting metal redox state. Apart from reporting their chemical characterization, I-V characteristics of these complexes in film state are investigated using sandwich-type devices comprising of a thin film of 100-125 nm thickness placed between two gold-plated ITO electrodes. These showed memory switching properties covering a useful voltage range with a reasonable ON/OFF ratio and also are suitable for RAM/ROM applications. I-V characteristics of two similar complexes of Rh and Cr with identical ligand environment and electronic structure are also referred for developing an insight into the memory switching ability of Ir- and Rh- complexes on the basis of comparative analysis of responses of the respective systems. In a nutshell, thorough analysis of voltage driven redox dynamics and corresponding solid and solution state current responses of all the systems are attempted and there from an unexplored class of switching devices are systematically introduced. PMID:24682999

  10. Role of axial base coordination in isonitrile binding and chalcogen atom transfer to vanadium(III) complexes.

    Science.gov (United States)

    Majumdar, Subhojit; Stauber, Julia M; Palluccio, Taryn D; Cai, Xiaochen; Velian, Alexandra; Rybak-Akimova, Elena V; Temprado, Manuel; Captain, Burjor; Cummins, Christopher C; Hoff, Carl D

    2014-10-20

    The enthalpy of oxygen atom transfer (OAT) to V[(Me3SiNCH2CH2)3N], 1, forming OV[(Me3SiNCH2CH2)3N], 1-O, and the enthalpies of sulfur atom transfer (SAT) to 1 and V(N[t-Bu]Ar)3, 2 (Ar = 3,5-C6H3Me2), forming the corresponding sulfides SV[(Me3SiNCH2CH2)3N], 1-S, and SV(N[t-Bu]Ar)3, 2-S, have been measured by solution calorimetry in toluene solution using dbabhNO (dbabhNO = 7-nitroso-2,3:5,6-dibenzo-7-azabicyclo[2.2.1]hepta-2,5-diene) and Ph3SbS as chalcogen atom transfer reagents. The V-O BDE in 1-O is 6.3 ± 3.2 kcal·mol(-1) lower than the previously reported value for 2-O and the V-S BDE in 1-S is 3.3 ± 3.1 kcal·mol(-1) lower than that in 2-S. These differences are attributed primarily to a weakening of the V-Naxial bond present in complexes of 1 upon oxidation. The rate of reaction of 1 with dbabhNO has been studied by low temperature stopped-flow kinetics. Rate constants for OAT are over 20 times greater than those reported for 2. Adamantyl isonitrile (AdNC) binds rapidly and quantitatively to both 1 and 2 forming high spin adducts of V(III). The enthalpies of ligand addition to 1 and 2 in toluene solution are -19.9 ± 0.6 and -17.1 ± 0.7 kcal·mol(-1), respectively. The more exothermic ligand addition to 1 as compared to 2 is opposite to what was observed for OAT and SAT. This is attributed to less weakening of the V-Naxial bond in ligand binding as opposed to chalcogen atom transfer and is in keeping with structural data and computations. The structures of 1, 1-O, 1-S, 1-CNAd, and 2-CNAd have been determined by X-ray crystallography and are reported. PMID:25280113

  11. Synthesis, Crystal Structure and Fluorescence Property of a Five- and Six-coordinated Trinuclear Zinc(II) Complex:{[ZnL(OAc)]2Zn}·CH3COCH3

    Institute of Scientific and Technical Information of China (English)

    DONG,Wen-Kui; ZHANG,Yan-Ping; ZHAO,Chun-Yu; TANG,Xiao-Lu; L(U),Zhong-Wu; ZOU,Zheng

    2008-01-01

    A novel linear trinuclear zinc(II) complex, {[ZnL(OAc)]2Zn}·CH3COCH3 (H2L: ethylenedioxybis(5-bromo-2-hydroxybenzylideneamino)), has been synthesized and structurally characterized. X-ray crystal structure of the complex reveals that three zinc(II) ions are coordinated by two tetradentate L2- units and two acetate ions acting as bridging groups. The coordination geometry around the terminal Zn(1) or Zn(1)#1 atom approaches a distorted square pyramid. The coordination sphere of the central Zn(2) atom constitutes a slightly distorted octahedral geometry. The blue-green emission from the zinc(II) complex can be observed, where the maximum emission wavelength is at 464 nm.

  12. Synthesis and Crystal Structure of a 1-D Chain Coordination Complex {[Mn2(HCAM)3(H2bipy)]·5H2O}n

    Institute of Scientific and Technical Information of China (English)

    SUN Ya-Guang; RONG Shu-Ting; WU Yong-Li; YU Wan; WANG Chuan-Sheng; ZHANO Wan-Zhong; GAO En-Jun

    2009-01-01

    The 1-D chain coordination complex of {[Mn2(HCAM)3(H2bipy)]·5H2O}n (H3CAM = 4-hydroxypyridine-2,6-dicarboxylic acid, bipy = 4,4'-bipyridine) has been synthesized by the reaction of 4-hydroxypyridine-2,6-dicarboxylic acid, 4,4'-bipyridine and manganese carbonate under hydrothermal conditions, and its crystal structure was determined by X-ray diffraction method. The crystal belongs to the monoclinie system, space group P21/n with a = 10.110(2), b = 20.159(4), c = 17.861(4) A, β = 99.67(3)°, V= 3.5884(12) nm3, Mr= 901.47, Z = 4, Dc= 1.669 g·cm-3, μ= 0.798 mm-1, F(000) = 1840, the final R = 0.0713 and wR = 0.1853. The complex forms a 1-D chain bridged by HCAM, protonated 4,4-bipyridines link the 1-D chains to construct 2-D networks via N-H…O hydrogen bonds, and networks are further extended via π-π stacking and hydrogen bonds into 3-D supramolecular framework.

  13. Synthesis, structure, spectra and reactivity of iron(III) complexes of facially coordinating and sterically hindering 3N ligands as models for catechol dioxygenases.

    Science.gov (United States)

    Sundaravel, Karuppasamy; Dhanalakshmi, Thirumanasekaran; Suresh, Eringathodi; Palaniandavar, Mallayan

    2008-12-28

    A series of 1 : 1 iron(III) complexes of sterically hindered and systematically modified tridentate 3N donor ligands have been isolated and studied as functional models for extradiol-cleaving catechol dioxygenases. All of them are of the type [Fe(L)Cl(3)], where L is N-methyl-N'-(pyrid-2-ylmethyl)ethylenediamine (L1), N-ethyl-N'-(pyrid-2-ylmethyl)ethylenediamine (L2), N-benzyl-N'-(pyrid-2-ylmethyl)ethylenediamine (L3), N,N-dimethyl-N'-(pyrid-2-ylmethyl)ethylenediamine (L4), N'-methyl-N'-(pyrid-2-ylmethyl)-N,N-dimethylethylenediamine (L5), N'-ethyl-N'-(pyrid-2-ylmethyl)-N,N-dimethylethylenediamine (L6) and N'-benzyl-N'-(pyrid-2-ylmethyl)-N,N-dimethylethylenediamine (L7). They have been characterized by elemental analysis and spectral and electrochemical methods. The X-ray crystal structures of the complexes [Fe(L2)Cl(3)] 2, [Fe(L3)Cl(3)] 3 and [Fe(L7)Cl(3)] 7 have been successfully determined. All the three complexes possess a distorted octahedral coordination geometry in which the ligand is facially coordinated to iron(III) and the chloride ions occupy the remaining coordination sites. Upon replacing the N-ethyl group on the terminal nitrogen donor in 2 by the bulky N-benzyl group as in 3, the terminal Fe-N bond distance increases slightly from 2.229(5) A to 2.244(5) A. Upon incorporating the sterically demanding N-benzyl group on the central nitrogen donor in 4 to obtain 7, the central Fe-N(amine) bond distance increases from 2.181(5) A to 2.299(2) A. The catecholate adducts [Fe(L)(DBC)(Cl)] and [Fe(L)(DBC)(Sol)](+), where H(2)DBC is 3,5-di-tert-butylcatechol and Sol = solvent (H(2)O/DMF), have been generated in situ and their spectral and redox properties and dioxygenase activities have been studied in N,N-dimethylformamide and dichloromethane solutions. The adducts [Fe(L)(DBC)(Sol)](+) undergo cleavage of DBC(2-) in the presence of molecular oxygen to afford both intra- and extradiol cleavage products. The extradiol products are higher in dichloromethane than in

  14. Structure, ligands and substrate coordination of the oxygen-evolving complex of photosystem II in the S2 state: a combined EPR and DFT study.

    Science.gov (United States)

    Lohmiller, Thomas; Krewald, Vera; Navarro, Montserrat Pérez; Retegan, Marius; Rapatskiy, Leonid; Nowaczyk, Marc M; Boussac, Alain; Neese, Frank; Lubitz, Wolfgang; Pantazis, Dimitrios A; Cox, Nicholas

    2014-06-28

    The S2 state of the oxygen-evolving complex of photosystem II, which consists of a Mn4O5Ca cofactor, is EPR-active, typically displaying a multiline signal, which arises from a ground spin state of total spin ST = 1/2. The precise appearance of the signal varies amongst different photosynthetic species, preparation and solvent conditions/compositions. Over the past five years, using the model species Thermosynechococcus elongatus, we have examined modifications that induce changes in the multiline signal, i.e. Ca(2+)/Sr(2+)-substitution and the binding of ammonia, to ascertain how structural perturbations of the cluster are reflected in its magnetic/electronic properties. This refined analysis, which now includes high-field (W-band) data, demonstrates that the electronic structure of the S2 state is essentially invariant to these modifications. This assessment is based on spectroscopies that examine the metal centres themselves (EPR, (55)Mn-ENDOR) and their first coordination sphere ligands ((14)N/(15)N- and (17)O-ESEEM, -HYSCORE and -EDNMR). In addition, extended quantum mechanical models from broken-symmetry DFT now reproduce all EPR, (55)Mn and (14)N experimental magnetic observables, with the inclusion of second coordination sphere ligands being crucial for accurately describing the interaction of NH3 with the Mn tetramer. These results support a mechanism of multiline heterogeneity reported for species differences and the effect of methanol [Biochim. Biophys. Acta, Bioenerg., 2011, 1807, 829], involving small changes in the magnetic connectivity of the solvent accessible outer MnA4 to the cuboidal unit Mn3O3Ca, resulting in predictable changes of the measured effective (55)Mn hyperfine tensors. Sr(2+) and NH3 replacement both affect the observed (17)O-EDNMR signal envelope supporting the assignment of O5 as the exchangeable μ-oxo bridge and it acting as the first site of substrate inclusion.

  15. Alkali-metal ion coordination in uranyl(VI) poly-peroxo complexes in solution, inorganic analogues to crown-ethers. Part 2. Complex formation in the tetramethyl ammonium-, Li(+)-, Na(+)- and K(+)-uranyl(VI)-peroxide-carbonate systems.

    Science.gov (United States)

    Zanonato, Pier Luigi; Szabó, Zoltán; Vallet, Valerie; Di Bernardo, Plinio; Grenthe, Ingmar

    2015-10-01

    The constitution and equilibrium constants of ternary uranyl(vi) peroxide carbonate complexes [(UO2)p(O2)q(CO3)r](2(p-q-r)) have been determined at 0 °C in 0.50 M MNO3, M = Li, K, and TMA (tetramethyl ammonium), ionic media using potentiometric and spectrophotometric data; (17)O NMR data were used to determine the number of complexes present. The formation of cyclic oligomers, "[(UO2)(O2)(CO3)]n", n = 4, 5, 6, with different stoichiometries depending on the ionic medium used, suggests that Li(+), Na(+), K(+) and TMA ions act as templates for the formation of uranyl peroxide rings where the uranyl-units are linked by μ-η(2)-η(2) bridged peroxide-ions. The templating effect is due to the coordination of the M(+)-ions to the uranyl oxygen atoms, where the coordination of Li(+) results in the formation of Li[(UO2)(O2)(CO3)]4(7-), Na(+) and K(+) in the formation of Na/K[(UO2)(O2)(CO3)]5(9-) complexes, while the large tetramethyl ammonium ion promotes the formation of two oligomers, TMA[(UO2)(O2)(CO3)]5(9-) and TMA[(UO2)(O2)(CO3)]6(11-). The NMR spectra demonstrate that the coordination of Na(+) in the five- and six-membered oligomers is significantly stronger than that of TMA(+); these observations suggest that the templating effect is similar to the one observed in the synthesis of crown-ethers. The NMR experiments also demonstrate that the exchange between TMA[(UO2)(O2)(CO3)]5(9-) and TMA[(UO2)(O2)(CO3)]6(11-) is slow on the (17)O chemical shift time-scale, while the exchange between TMA[(UO2)(O2)(CO3)]6(11-) and Na[(UO2)(O2)(CO3)]6(11-) is fast. There was no indication of the presence of large clusters of the type identified by Burns and Nyman (M. Nyman and P. C. Burns, Chem. Soc. Rev., 2012, 41, 7314-7367) and possible reasons for this and the implications for the synthesis of large clusters are briefly discussed.

  16. Two pathways for electrocatalytic oxidation of hydrogen by a nickel bis(diphosphine) complex with pendant amines in the second coordination sphere.

    Science.gov (United States)

    Yang, Jenny Y; Smith, Stuart E; Liu, Tianbiao; Dougherty, William G; Hoffert, Wesley A; Kassel, W Scott; Rakowski DuBois, M; DuBois, Daniel L; Bullock, R Morris

    2013-07-01

    A nickel bis(diphosphine) complex containing pendant amines in the second coordination sphere, [Ni(P(Cy)2N(t-Bu)2)2](BF4)2 (P(Cy)2N(t-Bu)2 = 1,5-di(tert-butyl)-3,7-dicyclohexyl-1,5-diaza-3,7-diphosphacyclooctane), is an electrocatalyst for hydrogen oxidation. The addition of hydrogen to the Ni(II) complex gives three isomers of the doubly protonated Ni(0) complex [Ni(P(Cy)2N(t-Bu)2H)2](BF4)2. Using the pKa values and Ni(II/I) and Ni(I/0) redox potentials in a thermochemical cycle, the free energy of hydrogen addition to [Ni(P(Cy)2N(t-Bu)2)2](2+) was determined to be -7.9 kcal mol(-1). The catalytic rate observed in dry acetonitrile for the oxidation of H2 depends on base size, with larger bases (NEt3, t-BuNH2) resulting in much slower catalysis than n-BuNH2. The addition of water accelerates the rate of catalysis by facilitating deprotonation of the hydrogen addition product before oxidation, especially for the larger bases NEt3 and t-BuNH2. This catalytic pathway, where deprotonation occurs prior to oxidation, leads to an overpotential that is 0.38 V lower compared to the pathway where oxidation precedes proton movement. Under the optimal conditions of 1.0 atm H2 using n-BuNH2 as a base and with added water, a turnover frequency of 58 s(-1) is observed at 23 °C.

  17. Versatile coordination modes of bis[5-(2-pyridine-2-yl)-1,2,4-triazole-3-yl]alkanes in Cu(II) complexes.

    Science.gov (United States)

    Gusev, Alexey N; Nemec, Ivan; Herchel, Radovan; Bayjyyev, Eziz; Nyshchimenko, Galyna A; Alexandrov, Grigory G; Eremenko, Igor L; Trávníček, Zdeněk; Hasegawa, Miki; Linert, Wolfgang

    2014-05-21

    Nine new mononuclear and polynuclear Cu(II) complexes [Cu(H2L(2))Cl]Cl·3H2O (1), [Cu(H2L(3))Cl]Cl·H2O (2), [Cu(H2L(4))Cl]Cl·2.5H2O (3), [Cu3(μ(3)-L(1))2(H2O)3](ClO4)2·H2O (4), [Cu4(μ-HL(1))4](ClO4)8·CH3OH·5H2O (5), [Cu2(HL(3))2](ClO4)2·2H2O (6a), [Cu2(μ-HL(3))2](ClO4)2·H2O (6b), [Cu2(μ-HL(3))(L(3))Cu(teta)](ClO4)3·2H2O (7) and [Cu2(H2L(3))2(ox)](ClO4)2·2H2O·2MeOH (8) containing [5-(2-pyridine-2-yl)-1,2,4-triazole-3-yl]alkanes (H2L(n), n = 1-4) in combination with other ligands, such as chlorido, aqua, triethylenetetramine (teta) and/or oxalato (ox(2-)), were synthesized and characterized by various techniques such as elemental analysis, FTIR, NMR and UV-Vis spectroscopy. X-ray structures of H2L(3) and H2L(4) as well as complexes 1-8 were determined. The X-ray structures revealed that relatively small composition and structural changes in the H2L(n) ligands have a substantial impact on the coordination geometries of the complexes themselves as well as on their resulting magnetic properties. It has been found that the geometries of the complexes vary from square-pyramidal to trigonal-bipyramidal (with τ ranging from 0.00 to 0.96) and, moreover, that the trigonal bipyramidal geometry becomes more preferable with the increase in the length of the polymethylene chain within the corresponding H2L(n) ligand. The magnetic properties of the polynuclear compounds 4, 5, 6, 7 and 8 were analysed using the spin Hamiltonian formalism, which revealed the presence of antiferromagnetic exchange in the polynuclear systems mediated by the title ligands. The significant effect of the geometric parameters on the Cu···Cu exchange interactions in the polynuclear complexes is discussed.

  18. Uranyl ion coordination

    Science.gov (United States)

    Evans, H.T.

    1963-01-01

    A review of the known crystal structures containing the uranyl ion shows that plane-pentagon coordination is equally as prevalent as plane-square or plane-hexagon. It is suggested that puckered-hexagon configurations of OH - or H2O about the uranyl group will tend to revert to plane-pentagon coordination. The concept of pentagonal coordination is invoked for possible explanations of the complex crystallography of the natural uranyl hydroxides and the unusual behavior of polynuclear ions in hydrolyzed uranyl solutions.

  19. Synthesis, structure and antifungal activity of thiophene-2,3-dicarboxaldehyde bis(thiosemicarbazone) and nickel(II), copper(II) and cadmium(II) complexes: unsymmetrical coordination mode of nickel complex.

    Science.gov (United States)

    Alomar, Kusaï; Landreau, Anne; Allain, Magali; Bouet, Gilles; Larcher, Gérald

    2013-09-01

    The reaction of nickel(II), copper(II) chlorides and cadmium(II) chloride and bromide with thiophene-2,3-dicarboxaldehyde bis(thiosemicarbazone) (2,3BTSTCH2) leads to a series of new complexes: [Ni(2,3BTSTCH)]Cl, [Cu(2,3BTSTC)], [CdCl2(2,3BTSTCH2)] and [CdBr2(2,3BTSTCH2)]. The crystal structures of the ligand and of [Ni(2,3BTSTCH)]Cl complex have been determined. In this case, we remark an unusual non-symmetrical coordination mode for the two functional groups: one acting as a thione and the second as a deprotonated thiolate. All compounds have been tested for their antifungal activity against human pathogenic fungi: Candida albicans, Candida glabrata and Aspergillus fumigatus, the cadmium complexes exhibit the highest antifungal activity. Cytotoxicity was evaluated using two biological methods: human MRC5 cultured cells and brine shrimp Artemia salina bioassay. PMID:23792913

  20. Crystal structure of cesium salt of Fe(3) thiosemicarbazonate complex at 298 and 103 K. Comparison of geometrical parameters of Fe3S2O2N2 octahedral coordination fragment in high- and low-spin complexes

    International Nuclear Information System (INIS)

    The crystal structure of a high spin cesium salt of the Fe(3), thiosemicarbazonate complex, Cs[Fe(tsa)2], (tsa-salicyl aldehyde thiosemicarbazone) at room temperature and 103 K, is determined. The parameters of the rhombic cell are: a=15, 285(3), b=13.402(4), c=9.449(8)A at 298 K and a=15.161(3), b=13.340(3), c=9.394(7)A at 103 K. The space group is Pna21, Z=4, the final values of R-factors are 0.054 (298 K, 1232 reflections) and 0.041 (103 K, 1597 reflections) taking into account the absorption of X-rays using the method of calculating corrections according to the crystal form and the anomalous scattering of Cs, Fe, S atoms. The structure is built of Cs+ cations and complex anions [Fe(tsa)2]-. The specific intermolecular interactions are absent. Fe-S and Fe-N bond lengths and the values of some inner angles of the coordination polyhedron of iron atom are taken as structural characteristics during the diagnostics of the Fe(3) ion spin state in thiosemicarbazonate complexes

  1. Six-coordinate high-spin iron(ii) complexes with bidentate PN ligands based on 2-aminopyridine - new Fe(ii) spin crossover systems.

    Science.gov (United States)

    Holzhacker, Christian; Calhorda, Maria José; Gil, Adrià; Carvalho, Maria Deus; Ferreira, Liliana P; Stöger, Berthold; Mereiter, Kurt; Weil, Matthias; Müller, Danny; Weinberger, Peter; Pittenauer, Ernst; Allmaier, Günter; Kirchner, Karl

    2014-08-01

    Several new octahedral iron(ii) complexes of the type [Fe(PN(R)-Ph)2X2] (X = Cl, Br; R = H, Me) containing bidentate PN(R)-Ph (R = H, Me) (1a,b) ligands based on 2-aminopyridine were prepared. (57)Fe Mössbauer spectroscopy and magnetization studies confirmed in all cases their high spin nature at room temperature with magnetic moments very close to 4.9μB reflecting the expected four unpaired d-electrons in all these compounds. While in the case of the PN(H)-Ph ligand an S = 2 to S = 0 spin crossover was observed at low temperatures, complexes with the N-methylated analog PN(Me)-Ph retain an S = 2 spin state also at low temperatures. Thus, [Fe(PN(H)-Ph)2X2] (2a,3a) and [Fe(PN(Me)-Ph)2X2] (2b,3b) adopt different geometries. In the first case a cis-Cl,P,N-arrangement seems to be most likely, as supported by various experimental data derived from (57)Fe Mössbauer spectroscopy, SQUID magnetometry, UV/Vis, Raman, and ESI-MS as well as DFT and TDDFT calculations, while in the case of the PN(Me)-Ph ligand a trans-Cl,P,N-configuration is adopted. The latter is also confirmed by X-ray crystallography. In contrast to [Fe(PN(Me)-Ph)2X2] (2b,3b), [Fe(PN(H)-Ph)2X2] (2a,3a) is labile and undergoes rearrangement reactions. In CH3OH, the diamagnetic dicationic complex [Fe(PN(H)-Ph)3](2+) (5) is formed via the intermediacy of cis-P,N-[Fe(κ(2)-P,N-PN(H)-Ph)2(κ(1)-P-PN(H)-Ph)(X)](+) (4a,b) where one PN ligand is coordinated in a κ(1)-P-fashion. In CH3CN the diamagnetic dicationic complex cis-N,P,N-[Fe(PN(H)-Ph)2(CH3CN)2](2+) (6) is formed as a major isomer where the two halide ligands are replaced by CH3CN.

  2. Peroxidase-benzhydroxamic acid complexes: spectroscopic evidence that a Fe-H2O distance of 2.6 A can correspond to hexa-coordinate high-spin heme.

    Science.gov (United States)

    Smulevich, G; Feis, A; Indiani, C; Becucci, M; Marzocchi, M P

    1999-02-01

    Resonance Raman (RR) spectra have been obtained for single-crystal horseradish peroxidase isozyme C complexed with benzhydroxamic acid (BHA). The data are compared with those obtained in solution by both RR and electronic absorption spectroscopies at room and low (12-80 K) temperatures. Moreover, the analysis has been extended to Coprinus cinereus peroxidase complexed with BHA. The results obtained for the two complexes are very similar and are consistent with the presence of an aqua six-coordinate high-spin heme. Therefore it can be concluded that despite the rather long Fe-H2O distance of 2.6-2.7 A found by X-ray crystallography in both complexes, the distal water molecule can still coordinate to the heme iron.

  3. Spectroscopic Studies of a Three-dimensional, Five-coordinated Copper(Ⅱ) Complex via Hydrogen Bonds: [Cu(PDA)(H2O)2](H2PDA=Pyridine-2,6-dicarboxylic Acid)

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new copper(Ⅱ) complex [Cu(PDA)(H2O)2] was synthesized and its structure was determined. Cu(Ⅱ) is five-coordinated in a tetragonal pyramid geometry. The two coordinating water molecules are different and the two Cu-O bond lengths differ by nearly 0.02 nm. The whole crystal is linked to form a three-dimensional network by means of hydrogen bonds. The X-band ESR spectrum shows three different g tensors with a well-resolved hyperfine structure in the gz signal, giving the ESR parameters gx=2.05, gy=2.065 and gz=2.29. The covalency of the coordinate bonds and the deviation from tetragonal pyramid geometry for the complex are discussed based on the ESR spectra.

  4. The coordination chemistry of boron porphyrin complexes B2OX2 (TYPP) (X = OH, F; Y = Cl, CH3) and their chemical reactivities

    Indian Academy of Sciences (India)

    G I Cárdenas-Jirón; F Espinoza-Leyton; T L Sordo

    2005-09-01

    The structure and coordination chemistry of boron porphyrin complexes B2OX2 (TYPP) (X = OH, F; Y = Cl, CH3) in connection with its chemical reactivity are analyzed at ab initio density functional theory B3LYP/6-31G∗ and restricted Hartree-Fock RHF/6-31G∗ levels of theory. Global reactivity and local selectivity descriptors are used as adequate tools to analyze the isomerism effect ( or isomer) and the substitution effect (X: in axial ligand; or Y: in porphyrin ligand). In all the cases, we find that the conformation is the most stable one, in agreement with X-ray results, and that a principle of maximum hardness in the isomerism analysis is fullfilled. In the substitution analysis, we find that the three global reactivity indexes (, , ) and the two local reactivity indexes (, electrostatic potential) used in this paper predict the same trend when an electron-withdrawing substituent is replaced by an electron donor. Finally, we show that substitution in the porphyrin ligand is slightly more significant than that in the axial ligand.

  5. Cyclic M2(RL)2 coordination complexes of 5-(3-[N-tert-Butyl-N-aminoxyl]phenyl)pyrimidine with paramagnetic transition metal dications.

    Science.gov (United States)

    Baskett, Martha; Lahti, Paul M; Paduan-Filho, Armando; Oliveira, Nei F

    2005-09-19

    5-(3-(N-tert-Butyl-N-aminoxyl)phenyl)pyrimidine (RL = 3NITPhPyrim) forms isostructural cyclic M2(RL)2 cyclic dimers with M(hfac)2 (M = Mn, Co, Cu; hfac = hexafluoroacetylacetonate). Mn2(hfac)4(RL)2 exhibits strong antiferromagnetic Mn-RL exchange, with weak ferromagnetic exchange (0.7 cm(-1)) between Mn-RL units that is consistent with a spin polarization exchange mechanism. The magnetic moment of Co2(hfac)4(RL)2 at higher temperatures is consistent with strongly antiferromagnetic exchange within the Co-NIT units and tends toward zero below 50 K at lower magnetic fields. Cu2(hfac)4(RL)2 shows more complex behavior, with no high-temperature plateau in chiT(T) up to 300 K but a monotonic decrease down to about 100 K. The Cu(II)-nitroxide bonds decrease by 0.2-0.3 A over the same temperature range, corresponding to a change of nitroxide coordination from axial to equatorial. This thermally reversible Jahn-Teller distortion leads to a thermally induced spin state conversion from a high-spin, paramagnetic state at higher temperature to a low-spin state at lower temperature. This spin state conversion is accompanied by a reversible solid-state thermochromic change between dull yellow-brown at room temperature and green at 77 K. PMID:16156631

  6. Crystal structure and properties of complexes [Ln(Gly)4Im·(ClO4)4]n (Ln:Nd, Sm) constructed from eight-coordination containing square antiprism

    Science.gov (United States)

    Pan, Lu; Gao, Xiao-han; Lv, Xue-chuan; Tan, Zhi-cheng; Cao, Hui

    2016-08-01

    Two eight-coordination containing square antiprism polyhedra, [Ln(Gly)4Im·(ClO4)4]n (Ln:Nd, Sm) were synthesized through the self-assembly of Ln3+ (Ln:Nd, Sm) ions, glycine and imidazole in aqueous solution and characterized by X-ray single crystal diffraction. Both of the complexes crystallized in the C2/c space group. In the cluster, each Ln3+ ions was eight-coordination by eight oxygen atoms of the glycine. The coordination sphere of each Ln3+ ions could be described as a distorted square antiprism. Two central Ln3+ ions were connected by four bridging carboxyl groups from four glycine molecules. The Ln-O bond distances were related to the coordination geometries of the ligands. The complexes had two special solid-solid phase transitions at 224 K and 248 K, which were interpreted as a freezing-in phenomenon of the reorientational motion of perchlorate ions ClO4- and the orientational order/disorder process of ClO4- ions. The decomposition mechanism of the complexes was deduced to be three stages from 300 to 700 K. The fluorescent excitation and emission spectra showed that the complexes had strong fluorescent property.

  7. Introduction to Coordination Chemistry

    CERN Document Server

    Lawrance, Geoffrey Alan

    2010-01-01

    Introduction to Coordination Chemistry examines and explains how metals and molecules that bind as ligands interact, and the consequences of this assembly process. This book describes the chemical and physical properties and behavior of the complex assemblies that form, and applications that may arise as a result of these properties. Coordination complexes are an important but often hidden part of our world?even part of us?and what they do is probed in this book. This book distills the essence of this topic for undergraduate students and for research scientists.

  8. Poisson Coordinates.

    Science.gov (United States)

    Li, Xian-Ying; Hu, Shi-Min

    2013-02-01

    Harmonic functions are the critical points of a Dirichlet energy functional, the linear projections of conformal maps. They play an important role in computer graphics, particularly for gradient-domain image processing and shape-preserving geometric computation. We propose Poisson coordinates, a novel transfinite interpolation scheme based on the Poisson integral formula, as a rapid way to estimate a harmonic function on a certain domain with desired boundary values. Poisson coordinates are an extension of the Mean Value coordinates (MVCs) which inherit their linear precision, smoothness, and kernel positivity. We give explicit formulas for Poisson coordinates in both continuous and 2D discrete forms. Superior to MVCs, Poisson coordinates are proved to be pseudoharmonic (i.e., they reproduce harmonic functions on n-dimensional balls). Our experimental results show that Poisson coordinates have lower Dirichlet energies than MVCs on a number of typical 2D domains (particularly convex domains). As well as presenting a formula, our approach provides useful insights for further studies on coordinates-based interpolation and fast estimation of harmonic functions.

  9. Intercomparison of terrain-following coordinate transformation and immersed boundary methods in large-eddy simulation of wind fields over complex terrain

    Science.gov (United States)

    Fang, Jiannong; Porté-Agel, Fernando

    2016-09-01

    Accurate modeling of complex terrain, especially steep terrain, in the simulation of wind fields remains a challenge. It is well known that the terrain-following coordinate transformation method (TFCT) generally used in atmospheric flow simulations is restricted to non-steep terrain with slope angles less than 45 degrees. Due to the advantage of keeping the basic computational grids and numerical schemes unchanged, the immersed boundary method (IBM) has been widely implemented in various numerical codes to handle arbitrary domain geometry including steep terrain. However, IBM could introduce considerable implementation errors in wall modeling through various interpolations because an immersed boundary is generally not co-located with a grid line. In this paper, we perform an intercomparison of TFCT and IBM in large-eddy simulation of a turbulent wind field over a three-dimensional (3D) hill for the purpose of evaluating the implementation errors in IBM. The slopes of the three-dimensional hill are not steep and, therefore, TFCT can be applied. Since TFCT is free from interpolation-induced implementation errors in wall modeling, its results can serve as a reference for the evaluation so that the influence of errors from wall models themselves can be excluded. For TFCT, a new algorithm for solving the pressure Poisson equation in the transformed coordinate system is proposed and first validated for a laminar flow over periodic two-dimensional hills by comparing with a benchmark solution. For the turbulent flow over the 3D hill, the wind-tunnel measurements used for validation contain both vertical and horizontal profiles of mean velocities and variances, thus allowing an in-depth comparison of the numerical models. In this case, TFCT is expected to be preferable to IBM. This is confirmed by the presented results of comparison. It is shown that the implementation errors in IBM lead to large discrepancies between the results obtained by TFCT and IBM near the surface

  10. Practically Coordinating

    OpenAIRE

    Durfee, Edmund H.

    1999-01-01

    To coordinate, intelligent agents might need to know something about themselves, about each other, about how others view themselves and others, about how others think others view themselves and others, and so on. Taken to an extreme, the amount of knowledge an agent might possess to coordinate its interactions with others might outstrip the agent's limited reasoning capacity (its available time, memory, and so on). Much of the work in studying and building multiagent systems has thus been dev...

  11. Synthesis, magnetic and spectral studies on polystyrene-anchored coordination complexes of bi-, tri-, tetra- and hexavalent metal ions with unsymmetrical dibasic tetradentate ONNO donor Schiff base derived from 3-formylsalicylic acid, ethylenediamine and 2-benzoylacetanilide

    Indian Academy of Sciences (India)

    Dinesh Kumar; Arun Syamal; Jaipal; Lalit Kumar Sharma

    2009-01-01

    Polystyrene-anchored Cu(II), Zn(II), Cd(II), Ni(II), Mn(II), MoO2(II), UO2(II), Fe(III) and Zr(IV), complexes of the unsymmetrical dibasic tetradentate ONNO donor Schiff base derived from the condensation of chloromethylated polystyrene, 3-formylsalicylic acid, ethylenediamine and 2-benzoylacetanilide (PS-LH2) has been synthesized. The polystyrene anchored complexes have the formulae: PS-LM (where M = Cu, Zn, Cd, Ni, MoO2, UO2), PS-LFeCl.DMF, PS-LMn.2DMF and PS-LZr(OH)2.DMF. The polystyrene-anchored coordination compounds have been characterized by elemental analysis, IR, reflectance, ESR and magnetic susceptibility measurements. The per cent reaction conversion of polystyrene anchored Schiff base to polystyrene supported coordination compounds lies between 28.98 and 85.9. The coordinated dimethylformamide is completely lost on heating the complexes. The shifts of the ν(C=N)(azomethine) and ν(C-O)(phenolic) stretches have been monitored in order to find out the donor sites of the ligands. The Cu(II) complex is paramagnetic with square planar structure; the Ni(II) complex is diamagnetic with square planar structure; the Zn(II) and Cd(II) complexes are diamagnetic and have tetrahedral structure; the Mn(II) and Fe(III) complexes are paramagnetic and have octahedral structure; the MoO2(II) and UO2(II) complexes are diamagnetic and have octahedral structure and the Zr(IV) complexes are diamagnetic and have pentagonal bipyramidal structure.

  12. An elusive vinyl radical isolated as an appended unit in a five-coordinate Co(iii)-bis(iminobenzosemiquinone) complex formed via ligand-centered C-S bond cleavage.

    Science.gov (United States)

    Sarkar, Prasenjit; Tiwari, Archana; Sarmah, Amrit; Bhandary, Subhrajyoti; Roy, Ram Kinkar; Mukherjee, Chandan

    2016-08-23

    Redox-active ligand H4Pra(edt(AP/AP)) experienced C-S bond cleavage during complexation reaction with Co(OAc)2·2H2O in the presence of Et3N in CH3OH in air. Thus, formed complex 1 was composed of two iminobenzosemiquinone radicals in its coordination sphere and an unprecedented stable tethered-vinyl radical. The complex has been characterized by mass, X-ray single crystal, X-band EPR, variable-temperature magnetic moment measurements and DFT based computational study.

  13. Synthesis, structures and electrochemical properties of two novel metal-organic coordination complexes based on trimesic acid (H 3BTC) and 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (BPO)

    Science.gov (United States)

    Wang, Xiu-Li; Li, Jin; Lin, Hong-Yan; Hu, Hai-Liang; Chen, Bao-Kuan; Mu, Bao

    2009-12-01

    Two novel metal-organic coordination complexes [Cu(HBTC)(BPO)]·H 2O ( 1) and [Co 3(BTC) 2(BPO) 3(H 2O) 2]·5.25H 2O ( 2), have been synthesized from hydrothermal reaction of metal chloride with the mixed ligands 1,3,5-benzenetricarboxylate (H 3BTC) and bent dipyridyl based ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (BPO), and structurally characterized by elemental analyses, IR, TG and single-crystal X-ray diffraction analysis. The results reveal that each dinuclear Cu II unit is bridged by two kinds of different ligands (H 3BTC and BPO) to form one-dimensional (1-D) chain structure in complex 1. The adjacent chains for 1 are further linked by π-π stacking interactions and hydrogen bonding interactions to form a three-dimensional (3-D) supramolecular framework. Complex 2 possesses a 3-D network composed of three different cobalt(II) centers [carboxylate-bridged dinuclear cobalt units and mononuclear cobalt ion] and bridging ligands BTC and BPO, which presents the first example of 3-D coordination polymer constructed from the BPO ligands simultaneously showing three different coordination modes. Moreover, the electrochemical behaviors of the two complexes bulk-modified carbon paste electrodes ( 1-CPE and 2-CPE) have been reported.

  14. Mechanochemical Synthesis of 3d Transition-Metal-1,2,4-Triazole Complexes as Precursors for Microwave-Assisted and Thermal Conversion to Coordination Polymers with a High Influence on the Dielectric Properties.

    Science.gov (United States)

    Brede, Franziska A; Heine, Johanna; Sextl, Gerhard; Müller-Buschbaum, Klaus

    2016-02-18

    The complexes [MCl2 (TzH)4] (M=Mn (1), Fe (2); TzH=1,2,4-1H-triazole) and [ZnCl2 (TzH)2] (3) have been obtained by mechanochemical reactions of the corresponding divalent metal chloride and 1,2,4-1H-triazole. They were successfully used as precursors for the formation of coordination polymers either by a microwave-assisted reaction or by thermal conversion. For manganese, the conversion directly yielded 1∞ [MnCl2 TzH] (4), whereas for the iron-containing precursor, 1∞ [FeCl2 TzH] (6), was formed via the intermediate coordination polymer 1∞ [FeCl(TzH)2]Cl (5). For cobalt, the isotypic polymer 1∞ [CoCl(TzH)2]Cl (7) was obtained, but exclusively by a microwave-induced reaction directly from CoCl2 . The crystal structures were resolved from single crystals and powders. The dielectric properties were determined and revealed large differences in permittivity between the precursor complexes and the rigid chain-like coordination polymers. Whereas the monomeric complexes exhibit very different dielectric behaviour, depending on the transition metal, from "low-k" to "high-k" with the permittivity ranging from 4.3 to >100 for frequencies of up to 1000 Hz, the coordination polymers and complexes with strong intermolecular interactions are all close to "low-k" materials with very low dielectric constants up to 50 °C. Therefore, the conversion procedures can be used to deliberately influence the dielectric properties from complex to polymer and for different 3d transition-metal ions.

  15. Implementation and effectiveness of 'care navigation', coordinated management for people with complex chronic illness: rationale and methods of a randomised controlled

    OpenAIRE

    Plant, Natalie; Mallitt, Kylie-Ann; Kelly, Patrick J.; Usherwood, Tim; Gillespie, James; Boyages, Steven; Jan, Stephen; McNab, Justin; Essue, Beverley M.; Gradidge, Kathy; Maranan, Nereus; Ralphs, David; Aspin, Clive; Leeder, Stephen

    2013-01-01

    Background Chronic illness is a significant driver of the global burden of disease and associated health care costs. People living with severe chronic illness are heavy users of acute hospital services; better coordination of their care could potentially improve health outcomes while reducing hospital use. The Care Navigation trial will evaluate an in-hospital coordinated care intervention on health service use and quality of life in chronically ill patients. Methods/Design A randomised contr...

  16. Persistent coordination patterns in a complex task after 10 years delay: subtitle: how validate the old saying "once you have learned how to ride a bicycle, you never forget!".

    Science.gov (United States)

    Nourrit-Lucas, Déborah; Zelic, Grégory; Deschamps, Thibault; Hilpron, Michael; Delignières, Didier

    2013-12-01

    Motor learning studies have for a long time focused on performance variables (in terms of speed or accuracy) in assessing learning, transfer and retention of motor skills. We argue, however, that learning essentially resides in changes in coordination variables (in terms of qualitative organization of behavior) and that relevant tests for assessing the effectiveness of learning and retention should consider these variables. The aim of this experiment was to test the retention of a complex motor skill, after a long-term delay. Ten years ago, five participants were involved in an experiment during which they practiced for 39 sessions of ten 1-min trials on a ski-simulator. All participants volunteered for a retention test, ten years after, for one session of ten 1-min trials. Analyses focused on the oscillations of the platform of the simulator. Performance was assessed in terms of amplitude and frequency. Coordination was accounted for by an analysis of dynamical properties of the motion of the platform, and especially the nature of the damping function that was exploited for sustaining the limit cycle dynamics. Results showed a significant decrement in performance variables. In contrast, all participants adopted from the first trial onwards the coordination mode they learned 10years ago. These results confirm the strong persistence of coordination modes, once acquired and stabilized in the behavioral repertoire. They also support the importance of coordination variables for a valid assessment of learning and retention.

  17. Electronic structure study of seven-coordinate first-row transition metal complexes derived from 1,10-diaza-15-crown-5: a successful marriage of theory with experiment.

    Science.gov (United States)

    Platas-Iglesias, Carlos; Vaiana, Lea; Esteban-Gómez, David; Avecilla, Fernando; Real, José Antonio; de Blas, Andrés; Rodríguez-Blas, Teresa

    2005-12-26

    A detailed study of the electronic structure of seven-coordinate Mn(II), Co(II), and Ni(II) complexes with the lariat ether N,N'-bis(2-aminobenzyl)-1,10-diaza-15-crown-5 (L(1)) is presented. These complexes represent new examples of structurally characterized seven-coordinate (pentagonal bipyramidal) complexes for the Mn(II), Co(II), and Ni(II) ions. The X-ray crystal structures of the Mn(II) and Co(II) complexes show C(2) symmetries for the [M(L(1))](2+) cations, whereas the structures of the Ni(II) complexes show a more distorted coordination environment. The magnetic properties of the Mn(II) complex display a characteristic Curie law, whereas those of the Co(II) and Ni(II) ions show the occurrence of zero-field splitting of the S = 3/2 and 1 ground states, respectively. Geometry optimizations of the [M(L(1))](2+) systems (M = Mn, Co, or Ni) at the DFT (B3LYP) level of theory provide theoretical structures in good agreement with the experimental data. Electronic structure calculations predict a similar ordering of the metal-based beta spin frontier MO for the Mn(II) and Co(II) complexes. This particular ordering of the frontier MO leads to a pseudodegenerate ground state for the d(8) Ni(II) ion. The distortion of the C(2) symmetry in [Ni(L(1))](2+) is consistent with a Jahn-Teller effect that removes this pseudodegeneracy. Our electronic structure calculations predict that the binding strength of L(1) should follow the trend Co(II) approximately Mn(II) > Ni(II), in agreement with experimental data obtained from spectrophotometric titrations.

  18. Complexity

    CERN Document Server

    Gershenson, Carlos

    2011-01-01

    The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.

  19. Coordinated unbundling

    DEFF Research Database (Denmark)

    Timmermans, Bram; Zabala-Iturriagagoitia, Jon Mikel

    2013-01-01

    not focused on the role this policy instrument can play in the promotion of (knowledge-intensive) entrepreneurship. This paper investigates this link in more detail and introduces the concept of coordinated unbundling as a strategy that can facilitate this purpose. We also present a framework on how...

  20. Equatorially coordinated lanthanide single ion magnets.

    Science.gov (United States)

    Zhang, Peng; Zhang, Li; Wang, Chao; Xue, Shufang; Lin, Shuang-Yan; Tang, Jinkui

    2014-03-26

    The magnetic relaxation dynamics of low-coordinate Dy(III) and Er(III) complexes, namely three-coordinate ones with an equatorially coordinated triangle geometry and five-coordinate ones with a trigonal bipyramidal geometry, have been exploited for the first time. The three-coordinate Er-based complex is the first equatorially coordinated mononuclear Er-based single-molecule magnet (SMM) corroborating that simple models can effectively direct the design of target SMMs incorporating 4f-elements. PMID:24625001

  1. Room-Temperature Energy-Sampling Kβ X-ray Emission Spectroscopy of the Mn4Ca Complex of Photosynthesis Reveals Three Manganese-Centered Oxidation Steps and Suggests a Coordination Change Prior to O2 Formation.

    Science.gov (United States)

    Zaharieva, Ivelina; Chernev, Petko; Berggren, Gustav; Anderlund, Magnus; Styring, Stenbjörn; Dau, Holger; Haumann, Michael

    2016-08-01

    In oxygenic photosynthesis, water is oxidized and dioxygen is produced at a Mn4Ca complex bound to the proteins of photosystem II (PSII). Valence and coordination changes in its catalytic S-state cycle are of great interest. In room-temperature (in situ) experiments, time-resolved energy-sampling X-ray emission spectroscopy of the Mn Kβ1,3 line after laser-flash excitation of PSII membrane particles was applied to characterize the redox transitions in the S-state cycle. The Kβ1,3 line energies suggest a high-valence configuration of the Mn4Ca complex with Mn(III)3Mn(IV) in S0, Mn(III)2Mn(IV)2 in S1, Mn(III)Mn(IV)3 in S2, and Mn(IV)4 in S3 and, thus, manganese oxidation in each of the three accessible oxidizing transitions of the water-oxidizing complex. There are no indications of formation of a ligand radical, thus rendering partial water oxidation before reaching the S4 state unlikely. The difference spectra of both manganese Kβ1,3 emission and K-edge X-ray absorption display different shapes for Mn(III) oxidation in the S2 → S3 transition when compared to Mn(III) oxidation in the S1 → S2 transition. Comparison to spectra of manganese compounds with known structures and oxidation states and varying metal coordination environments suggests a change in the manganese ligand environment in the S2 → S3 transition, which could be oxidation of five-coordinated Mn(III) to six-coordinated Mn(IV). Conceivable options for the rearrangement of (substrate) water species and metal-ligand bonding patterns at the Mn4Ca complex in the S2 → S3 transition are discussed.

  2. Influence of terminal acryloyl arms on the coordination chemistry of a ditopic pyrimidine-hydrazone ligand: comparison of Pb(II), Zn(II), Cu(II), and Ag(I) complexes.

    Science.gov (United States)

    Hutchinson, Daniel J; Hanton, Lyall R; Moratti, Stephen C

    2013-03-01

    A new ditopic pyrimidine-hydrazone ligand, 6-hydroxymethylacryloyl-2-pyridinecarboxaldehyde, 2,2'-[2,2'-(2-methyl-4,6-pyrimidinediyl)bis(1-methylhydrazone)] (L2), was synthesized with terminal acryloyl functional groups to allow incorporation into copolymer gel actuators. NMR spectroscopy was used to show that L2 adopted a horseshoe shape with transoid-transoid pym-hyz-py linkages. Metal complexation studies were performed with L2 and salts of Pb(II), Zn(II), Cu(II), and Ag(I) ions in CH3CN in a variety of metal to ligand ratios. Reacting L2 with an excess amount of any of the metal ions resulted in linear complexes where the pym-hyz-py linkages were rotated to a cisoid-cisoid conformation. NMR spectroscopy showed that the acryloyl arms of L2 did not interact with the bound metal ions in solution. Seven of the linear complexes (1-7) were crystallized and analyzed by X-ray diffraction. Most of these complexes (4-7) also showed no coordination between the acryloyl arms and the metal ions; however, complexes 1-3 showed some interactions. Both of the acryloyl arms were coordinated to Pb(II) ions in [Pb2L2(SO3CF3)4] (1), one through the carbonyl oxygen donor and the other through the alkoxy oxygen donor. One of the acryloyl arms of [Cu2L2(CH3CN)3](SO3CF3)4 (2) was coordinated to one of the Cu(II) ions through the carbonyl oxygen donor. There appeared to be a weak association between the alkoxy donors of the acryloyl arms and the Pb(II) ions of [Pb2L2(ClO4)4]·CH3CN (3). Reaction of excess AgSO3CF3 with L2 was repeated in CD3NO2, resulting in crystals of {[Ag7(L2)2(SO3CF3)6(H2O)2] SO3CF3}∞ (8), the polymeric structure of which resulted from coordination between the carbonyl donors of the acryloyl arms and the Ag(I) ions. In all cases the coordination and steric effects of the acryloyl arms did not inhibit isomerization of the pym-hyz bonds of L2 or the core shape of the linear complexes.

  3. Theoretical studies in local coordination and vibrational spectra of M +CH 3O(CH 2CH 2O) nCH 3 ( n = 2-7) complexes (M = Na, K, Mg and Ca)

    Science.gov (United States)

    Dhumal, Nilesh R.; Gejji, Shridhar P.

    2006-04-01

    Solid polymer electrolytes (SPE) comprised of poly(ethylene oxide) (PEO) oligomers complexed with alkali metal salt of weakly coordinating anions have been of a great interest due to their high ionic conductivity. Ion pair formation influence the number of charge carriers and is an important factor underlying the ion transport phenomenon. In this work, the electronic structure and vibrational spectra of the metal ion-PEO oligomer represented by M-CH 3O(CH 2CH 2O) nCH 3 ( n = 2-7) (M = Na +, K +, Mg 2+ and Ca 2+) are obtained by employing the ab initio and hybrid density functional methods. Structural and spectral consequences of PEO oligomers to the alkali- and alkaline earth-metal ion coordination in different chemical environments have been presented. In metal ion-PEO oligomer ion-pairs the Mg 2+ ion binds strongly to ether oxygens of polyether complexes. The density functional calculations predict the heptaglyme ( n = 7 in the above series) binds strongly to the metal ion. The frequency shifts of characteristics vibrations induced by the metal ion-coordination in CH 3O(CH 2CH 2O) nCH 3-M ( n = 2-7) complexes have been discussed.

  4. Carbon-carbon cross-coupling reactions catalyzed by a two-coordinate nickel(II)-bis(amido) complex via observable Ni(I) , Ni(II) , and Ni(III) intermediates.

    Science.gov (United States)

    Lipschutz, Michael I; Tilley, T Don

    2014-07-01

    Recently, the development of more sustainable catalytic systems based on abundant first-row metals, especially nickel, for cross-coupling reactions has attracted significant interest. One of the key intermediates invoked in these reactions is a Ni(III) -alkyl species, but no such species that is part of a competent catalytic cycle has yet been isolated. Herein, we report a carbon-carbon cross-coupling system based on a two-coordinate Ni(II) -bis(amido) complex in which a Ni(III) -alkyl species can be isolated and fully characterized. This study details compelling experimental evidence of the role played by this Ni(III) -alkyl species as well as those of other key Ni(I) and Ni(II) intermediates. The catalytic cycle described herein is also one of the first examples of a two-coordinate complex that competently catalyzes an organic transformation, potentially leading to a new class of catalysts based on the unique ability of first-row transition metals to accommodate two-coordinate complexes.

  5. Synthesis, molecular and crystal structure of bis(triethanolamine)manganese(II) saccharinate: a seven-coordinate manganese complex with tri- and tetradentate triethanolamine ligands

    Science.gov (United States)

    Topcu, Yildiray; Andac, Omer; Yilmaz, Veysel T.; Harrison, William T. A.

    2002-06-01

    The synthesis, molecular and crystal structure of bis(triethanolamine)Mn(II) saccharinate, [Mn(tea) 2](sac) 2 are reported. The configuration of the tea ligands results in an unusual example of coordination number seven for the Mn(II) ion. The two triethanolamine (tea) ligands coordinate to the Mn(II) ion forming a monocapped trigonal prism geometry, in which one of the tea ligands behaves as a tridentate ligand, while the other one acts as a tetradentate donor. The free and coordinated hydroxyl hydrogens of the tea ligands are involved in hydrogen bonding with the amine nitrogen, carbonyl and sulfonyl oxygens of the neighbouring sac ions to form a three-dimensional infinite network. A weak π-π interaction between the phenyl rings of the sac ions also occurs.

  6. Syntheses, structural and spectral studies of six-coordinate, [Ph 2SnCl(acpm)], and seven-coordinate, [ nBu 2Sn(dapm)], diorganotin(IV) complexes with N, N, S-tridentate and S, N, N, N, S-pentadentate N4-heterocyclic thiosemicarbazones

    Science.gov (United States)

    de Sousa, Gerimário F.; Manso, Luís Carlos C.; Lang, Ernesto S.; Gatto, Claudia C.; Mahieu, Bernard

    2007-01-01

    The reaction of the N, N, S-tridentate ligand 2-acetylpyridine ( N4-morpholyl thiosemicarbazones), Hacpm, with Ph 2SnCl 2 leads to the formation of the six-coordinate complex [Ph 2SnCl(acpm)] ( 1), whereas the reaction of the S, N, N, N, S-pentadentate ligand 2,6-diacetylpyridine bis( N4-morpholyl thiosemicarbazone), H 2dapm, with nBu 2SnCl 2 leads to the formation of the seven-coordinate complex [ nBu 2Sn(dapm)] ( 2). Both compounds were studied by microanalyses, IR, NMR ( 1H, 13C, 119Sn) and Mössbauer spectroscopy to investigate their structural properties. The organotin(IV) complexes were also studied by single crystal X-ray diffraction and the structure determination revealed that the phenyl derivative crystallizes in the triclinic space group (P1¯) as discrete neutral molecules, with the tin(IV) ion in a distorted octahedral geometry with the acpm 1- ligand in a meridional configuration and the phenyl groups in trans positions. X-ray analysis shows that the n-butyl complex crystallizes in the monoclinic space group ( P2 1/ c) as discrete neutral complexes, with the tin(IV) ion in a distorted pentagonal bipyramidal geometry. A correlation between Mössbauer and X-ray data based on the point-charge model is discussed.

  7. Nitrate-Bridged One-Dimension Coordination Polymer Self-Assembled from a N4O2-Tetraiminodiphenolate Dicopper(II Macrocyclic Complex

    Directory of Open Access Journals (Sweden)

    Julio Cesar da Rocha

    2015-01-01

    Full Text Available Herein we report on the synthesis and single crystal X-ray structure characterization of [{Cu2(tidf(μ-NO3}∞]ClO4 (tidf = a Robson type macrocyclic ligand obtained upon condensation of 2,6-diformyl-4-methylphenol and 1,3-diaminopropane. The coordination geometry around the copper(II is square-pyramidal and has [Cu2(tidf]2+ units connected to each other through nitrate bridges extending as a one-dimension coordination polymer. The compound exhibits an extensive supramolecular structure supported by nonclassic hydrogen bonding between C-H⋯Operchlorate and C-H⋯Onitrate.

  8. Studies on coordination chemistry and bioactivity of metal complexes of a bidentate NN schiff base, (2-pyridyl-methylene)(phenyl) hydrazine, produced from the condensation of pyridine-2-carboxaldehyde with phenylhydrazine

    International Nuclear Information System (INIS)

    A bidentate Schiff base, (2-pyridyl-methylene)(phenyl) hydrazine, with NN donor sequence, was isolated from the condensation of pyridine-2-carboxaldehyde with phenylhydrazine in ethanol. Metal complexes of this ligand with Ni(II), Zn(It), and Cu(n) ions were synthesized and characterized by a variety of physico-chemical techniques. The structure of the Schiff base was solved by X-ray diffraction studies, which indicated that it was monoclinic with a space group of C2/c. The complexes were all four coordinated. The compounds were tested against four pathogenic bacteria and fungi. The nickel complex, [Ni(NN)2Cl2], in particular, was found to be active against all the fungi tested. The complexes were however inactive against leukemic cell lines (CEM-SS). (author)

  9. TECHNICAL COORDINATION

    CERN Multimedia

    A. Ball

    Overview From a technical perspective, CMS has been in “beam operation” state since 6th November. The detector is fully closed with all components operational and the magnetic field is normally at the nominal 3.8T. The UXC cavern is normally closed with the radiation veto set. Access to UXC is now only possible during downtimes of LHC. Such accesses must be carefully planned, documented and carried out in agreement with CMS Technical Coordination, Experimental Area Management, LHC programme coordination and the CCC. Material flow in and out of UXC is now strictly controlled. Access to USC remains possible at any time, although, for safety reasons, it is necessary to register with the shift crew in the control room before going down.It is obligatory for all material leaving UXC to pass through the underground buffer zone for RP scanning, database entry and appropriate labeling for traceability. Technical coordination (notably Stephane Bally and Christoph Schaefer), the shift crew and run ...

  10. Synthesis and structural characterization of silver(I), copper(I) coordination polymers and a helicate palladium(II) complex of dipyrrolylmethane-based dipyrazole ligands: the effect of meso substituents on structural formation.

    Science.gov (United States)

    Guchhait, Tapas; Barua, Bhagyasree; Biswas, Aritra; Basak, Biswanath; Mani, Ganesan

    2015-05-21

    A new class of multidentate dipyrrolylmethane based ditopic tecton, 1,9-bis(3,5-dimethylpyrazolylmethyl)dipyrrolylmethane, containing diethyl (L1) or cyclohexylidene (L2) substituents at the meso carbon atom were readily synthesized in 28-45% yields in two different ways starting from dipyrrolylmethanes. A one dimensional coordination polymer structure ([(L2)Ag][BF4])n was obtained when L2 was treated with AgBF4, whereas the analogous reaction between L1 and AgBF4 afforded the dicationic binuclear metallacycle complex [(L1)2Ag2][BF4]2. In addition, yet another coordination polymeric structure [(L1)CuI]n was obtained from the reaction between L1 and CuI. The analogous reaction of L1 with [Pd(PhCN)2Cl2] afforded the binuclear palladium complex [(L1)2Pd2Cl4] having a double-stranded helicate structure. The observed structural differences are attributed to the effects of the substituents present at the meso carbon atom of the ligand, in addition to the nature of the metal centre, coordination number and the preferred geometry.

  11. C-IBI: Targeting cumulative coordination within an iterative protocol to derive coarse-grained models of (multi-component) complex fluids.

    Science.gov (United States)

    de Oliveira, Tiago E; Netz, Paulo A; Kremer, Kurt; Junghans, Christoph; Mukherji, Debashish

    2016-05-01

    We present a coarse-graining strategy that we test for aqueous mixtures. The method uses pair-wise cumulative coordination as a target function within an iterative Boltzmann inversion (IBI) like protocol. We name this method coordination iterative Boltzmann inversion (C-IBI). While the underlying coarse-grained model is still structure based and, thus, preserves pair-wise solution structure, our method also reproduces solvation thermodynamics of binary and/or ternary mixtures. Additionally, we observe much faster convergence within C-IBI compared to IBI. To validate the robustness, we apply C-IBI to study test cases of solvation thermodynamics of aqueous urea and a triglycine solvation in aqueous urea.

  12. A new approach to suppress nonlinearity-transparency trade-off through coordination chemistry: syntheses and spectroscopic study on second-order nonlinear optical properties of a series of square-pyramidal zinc(II) complexes

    Science.gov (United States)

    Ren, Peng; Liu, Tao; Qin, Jingui; Chen, Chuangtian

    2003-03-01

    Five new square-pyramidal coordination compounds L · Zn(acac) 2 ( 1- 5) (acac=acetylacetonate; L is a variety of thiosemicarbazones: p-dimethylaminobenzaldehyde thiosemicarbazone ( 1), p-hydroxy- o-methoxybenzaldehyde thiosemicarbazone ( 2), p-methoxybenzaldehyde thiosemicarbazone ( 3), p-hydroxybenzaldehyde thiosemicarbazone ( 4), o-hydroxybenzaldehyde thiosemicarbazone ( 5)) have been synthesized and characterized by 1H NMR, IR, and elemental analysis. All of these compounds exhibit pretty wide transparent ranges in the visible region. Their electronic absorption spectra have been studied experimentally, and theoretically by ZINDO/S calculation. The latter has also been utilized to estimate the extent of intramolecular charge transfer. The MOPAC software package has been used to evaluate their first-order molecular hyperpolarizabilities ( β). All β values of the five coordination compounds are larger than those of the corresponding thiosemicarbazones. And complex 1 shows the largest β0 (39.1×10 -30 esu) in the series.

  13. Managing interteam coordination within and between organizations

    NARCIS (Netherlands)

    de Vries, Thomas Arend

    2015-01-01

    To accomplish complex tasks and effectively respond to environmental contingencies, teams must coordinate task-related issues with other teams (i.e., interteam coordination). Regrettably, interteam coordination is often complicated by misunderstandings that can arise from differences in teams’ langu

  14. TECHNICAL COORDINATION

    CERN Multimedia

    A. Ball

    2010-01-01

    Operational Experience At the end of the first full-year running period of LHC, CMS is established as a reliable, robust and mature experiment. In particular common systems and infrastructure faults accounted for <0.6 % CMS downtime during LHC pp physics. Technical operation throughout the entire year was rather smooth, the main faults requiring UXC access being sub-detector power systems and rack-cooling turbines. All such problems were corrected during scheduled technical stops, in the shadow of tunnel access needed by the LHC, or in negotiated accesses or access extensions. Nevertheless, the number of necessary accesses to the UXC averaged more than one per week and the technical stops were inevitably packed with work packages, typically 30 being executed within a few days, placing a high load on the coordination and area management teams. It is an appropriate moment for CMS Technical Coordination to thank all those in many CERN departments and in the Collaboration, who were involved in CMS techni...

  15. Preparation, Spectrochemical, and Computational Analysis of L-Carnosine (2-[(3-Aminopropanoylamino]-3-(1H-imidazol-5-ylpropanoic Acid and Its Ruthenium (II Coordination Complexes in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Myalo Sabela

    2011-12-01

    Full Text Available This study reports the synthesis and characterization of novel ruthenium (II complexes with the polydentate dipeptide, L-carnosine (2-[(3-aminopropanoylamino]-3-(1H-imidazol-5-ylpropanoic acid. Mixed-ligand complexes with the general composition [MLp(Clq(H2Or]·xH2O (M = Ru(II; L = L-carnosine; p = 3 − q; r = 0–1; and x = 1–3 were prepared by refluxing aqueous solutions of the ligand with equimolar amounts of ruthenium chloride (black-alpha form at 60 °C for 36 h. Physical properties of the complexes were characterized by elemental analysis, DSC/TGA, and cyclic voltammetry. The molecular structures of the complexes were elucidated using UV-Vis, ATR-IR, and heteronuclear NMR spectroscopy, then confirmed by density function theory (DFT calculations at the B3LYP/LANL2DZ level. Two-dimensional NMR experiments (1H COSY, 13C gHMBC, and 15N gHMBC were also conducted for the assignment of chemical shifts and calculation of relative coordination-induced shifts (RCIS by the complex formed. According to our results, the most probable coordination geometries of ruthenium in these compounds involve nitrogen (N1 from the imidazole ring and an oxygen atom from the carboxylic acid group of the ligand as donor atoms. Additional thermogravimetric and electrochemical data suggest that while the tetrahedral-monomer or octahedral-dimer are both possible structures of the formed complexes, the metal in either structure occurs in the (2+ oxidation state. Resulting RCIS values indicate that the amide-carbonyl, and the amino-terminus of the dipeptide are not involved in chelation and these observations correlate well with theoretical shift predictions by DFT.

  16. Observation of the inverse trans influence (ITI) in a uranium(V) imide coordination complex: an experimental study and theoretical evaluation.

    Science.gov (United States)

    Lam, Oanh P; Franke, Sebastian M; Nakai, Hidetaka; Heinemann, Frank W; Hieringer, Wolfgang; Meyer, Karsten

    2012-06-01

    An inverse trans influence has been observed in a high-valent U(V) imide complex, [(((Ad)ArO)(3)N)U(NMes)]. A thorough theoretical evaluation has been employed in order to corroborate the ITI in this unusual complex. Computations on the target complex, [(((Ad)ArO)(3)N)U(NMes)], and the model complexes [(((Me)ArO)(3)N)U(NMes)] and [(NMe(3))(OMe(2))(OMe)(3)U(NPh)] are discussed along with synthetic details and supporting spectroscopic data. Additionally, the syntheses and full characterization data of the related U(V) trimethylsilylimide complex [(((Ad)ArO)(3)N)U(NTMS)] and U(IV) azide complex [(((Ad)ArO)(3)N)U(N(3))] are also presented for comparison.

  17. Complexations of Ln(III) with SnS{sub 4}H and Sn{sub 2}S{sub 6}: Solvothermal syntheses and characterizations of lanthanide coordination polymers with thiostannate and polyamine mixed ligands

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chunying; Lu, Jialin; Han, Jingyu; Liu, Yun; Shen, Yali; Jia, Dingxian, E-mail: jiadingxian@suda.edu.cn

    2015-10-15

    Polymeric lanthanide complexes with thiostannate and polyamine mixed ligands, [Ln(peha)(μ–SnS{sub 4}H)]{sub n} [Ln=La (1a), Nd (1b)] and [(Ln(tepa)(μ–OH)){sub 2}(μ–Sn{sub 2}S{sub 6})]{sub n}nH{sub 2}O [Ln=Nd (2a), Sm (2b), Gd (2c), Dy (2d)] (peha=pentaethylenehexamine, tepa=tetraethylenepentamine) were respectively prepared in peha and tepa coordinative solvents by the solvothermal methods. In 1a and 1b, the Ln{sup 3+} ions are coordinated by a hexadentate peha ligand forming [Ln(peha)]{sup 3+} units. The [SnS{sub 4}H]{sup 3−} anion chelates a [Ln(peha)]{sup 3+} unit via two S atoms and coordinates to another [Ln(peha)]{sup 3+} unit via the third S atom. As a result, the [Ln(peha)]{sup 3+} units are connected into coordination polymers [Ln(peha)(μ–SnS{sub 4}H)]{sub n} by an unprecedented tridentate μ–η{sup 1},η{sup 2}–SnS{sub 4}H bridging ligands. In 2a–2d, the Ln{sup 3+} ions are coordinated by a pentadentate tepa ligand, and two [Ln(tepa)]{sup 3+} units are joined by two μ–OH bridges to form a binuclear [(Ln(tepa)(μ–OH)){sub 2}]{sup 4+} unit. Behaving as a bidentate μ–η{sup 1}, η{sup 1}–Sn{sub 2}S{sub 6} bridging ligand, the Sn{sub 2}S{sub 6} unit connects [(Ln(tepa)(μ–OH)){sub 2}]{sup 4+} units into a neutral coordination polymer [(Ln(tepa)(μ–OH)){sub 2}(μ–Sn{sub 2}S{sub 6})]{sub n} via the trans S atoms. The Ln{sup 3+} ions are in distorted monocapped square antiprismatic and bicapped trigonal prismatic environments in [(Ln(peha)(μ–SnS{sub 4}H)]{sub n} and [(Ln(tepa)(μ–OH)){sub 2}(μ–Sn{sub 2}S{sub 6})]{sub n}, respectively. The denticities of ethylene polyamine play an important role on the formation and complexation of the thiostannate in the presence of lanthanide ions. Compounds 1a–2d show well-defined absorption edges with band gaps between 2.81 and 3.15 eV. - Graphical abstract: Lanthanide coordination polymers concerning thiostannate ligands were prepared by the solvothermal methods, and μ{sub 3}

  18. Coordination Capacity

    CERN Document Server

    Cuff, Paul; Cover, Thomas

    2009-01-01

    We develop elements of a theory of cooperation and coordination in networks. Rather than considering a communication network as a means of distributing information, or of reconstructing random processes at remote nodes, we ask what dependence can be established among the nodes given the communication constraints. Specifically, in a network with communication rates between the nodes, we ask what is the set of all achievable joint distributions p(x1, ..., xm) of actions at the nodes on the network. Several networks are solved, including arbitrarily large cascade networks. Distributed cooperation can be the solution to many problems such as distributed games, distributed control, and establishing mutual information bounds on the influence of one part of a physical system on another.

  19. Enhancement of 4-electron O2 reduction by a Cu(ii)-pyridylamine complex via protonation of a pendant pyridine in the second coordination sphere in water.

    Science.gov (United States)

    Kotani, Hiroaki; Yagi, Tomomi; Ishizuka, Tomoya; Kojima, Takahiko

    2015-09-01

    We have synthesised a novel copper(ii) complex with a pyridine pendant as a proton relay port for electrocatalytic 4e(-) reduction of O2 in water. The enhancement of the electrocatalytic O2 reduction via protonation of the pyridine pendant is demonstrated in comparison with a copper(ii) complex without the pyridine pendant.

  20. Examination of the Coordination Sphere of AlIII in Trifluoromethyl-Heteroarylalkenolato Complex Ions by Gas-Phase IRMPD Spectroscopy and Computational Modelling

    NARCIS (Netherlands)

    Bruckmann, L.; Tyrra, W.; Mathur, S.; G. Berden,; Oomens, J.; Meijer, Ajhm; Schafer, M.

    2012-01-01

    A series of aluminium complex ions with trifluoromethyl-heteroarylalkenolato (TMHA) ligands are studied by gas-phase infrared multiphoton-dissociation (IRMPD) spectroscopy and computational modelling. The selected series of aluminium TMHA complex ions are promising species for the initial study of i

  1. Examination of the coordination sphere of AlIII in trifluoromethyl-heteroarylalkenolato complex ions by gas-phase IRMPD spectroscopy and computational modelling

    NARCIS (Netherlands)

    L. Brueckmann; W. Tyrra; S. Mathur; G. Berden; J. Oomens; A.J.H.M. Meijer; M. Schaefer

    2012-01-01

    A series of aluminium complex ions with trifluoromethyl-heteroarylalkenolato (TMHA) ligands are studied by gas-phase infrared multiphoton-dissociation (IRMPD) spectroscopy and computational modelling. The selected series of aluminium TMHA complex ions are promising species for the initial study of i

  2. Probing the orientations of coordination complex molecules onto the surface of ZnO nanoparticles by means of surface enhanced Raman scattering, UV–vis and DFT methods

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, Om; Gautam, Priyanka; Singh, Ranjan K., E-mail: ranjanksingh65@rediffmail.com

    2015-09-15

    Graphical abstract: - Highlights: • The adsorption geometry of three complex molecules onto the surface of ZnO nanoparticles is investigated by Raman, SERS and UV–vis techniques. • All the three complex molecules are adsorbed in flat-on geometry. • On the adsorption onto the ZnO NPs, the fluorescence background of Raman spectra of Zn complex is quenched. - Abstract: The surface enhanced Raman scattering (SERS) is a highly surface sensitive technique to study inter-surface properties of biological, organic, and inorganic materials. It is a precise technique to determine the adsorption geometry/orientation of the molecules as the intensity enhancement of the SERS bands depends on the adsorption geometry/orientation of molecules on SERS substrate. In the present work, Ni, Cu and Zn complexes of (Z)-N′(1,3,4-thiadiazol-2-yl) acetimidate were synthesized and adsorbed on ZnO nanoparticles. The surface enhanced Raman scattering (SERS), UV–vis and DFT techniques were applied to investigate the possible adsorption geometries of the complexes on ZnO. Consequently, it was found that the orientation of all three complex molecules is flat-on onto the surface of ZnO nanoparticles. The fluorescence background of Raman spectra of Zn complex is quenched and its geometry is isomerized after the adsorption onto the surface of ZnO nanoparticles. The adsorbed Cu complex on ZnO NPs absorbed UV radiations efficiently.

  3. A Novel Cobalt(II) Coordination Complex Constructed from H2Pyri and 4,4'-Bipy: Synthesis, Characterization and Bioactivity.

    Science.gov (United States)

    Gao, Enjun; Zhao, Fuchen; Zhu, Mingchang; Wang, Meilin

    2015-01-01

    The new complex of {[Co(4,4'-Bipy)(H2O)4]·(Pyri) · 3H2O}n (4,4'-Bipy = 4,4'-bipyridyl, H2Pyri = 3,5- Pyridinedicarboxylic acid) was synthesized and characterized by IR, element analysis and X-ray single-crystal diffraction. The binding of the complex with extracted HeLa cells DNA was investigated by UV and fluorescence spectrum. Gel electrophoresis assay demonstrated the ability of the complex cleaving the extracted HC-DNA. The complex exhibited a higher cytotoxicity against tumor cells in vitro. Furthermore, the apoptotic tests indicated the complex had an apoptotic effect on HeLa cells.

  4. Engineering Functionalization in a Supramolecular Polymer: Hierarchical Self-Organization of Triply Orthogonal Non-covalent Interactions on a Supramolecular Coordination Complex Platform.

    Science.gov (United States)

    Zhou, Zhixuan; Yan, Xuzhou; Cook, Timothy R; Saha, Manik Lal; Stang, Peter J

    2016-01-27

    Here we present a method for the construction of functionalizable supramolecular polymers by controlling three orthogonal interactions within a single system: (i) coordination-driven self-assembly; (ii) H-bonding; and (iii) host-guest interactions between crown ether and dialkylammonium substrates. Three unique molecules constitute the supramolecular construct, including a 2-ureido-4-pyrimidinone (UPy)-functionalized rigid dipyridyl donor and a complementary organoplatinum(II) acceptor decorated with a crown ether moiety that provide the basis for self-assembly and polymerization. The final host-guest interaction is demonstrated by using one of two dialkylammonium molecules containing fluorophores that bind to the benzo-21-crown-7 (B21C7) groups of the acceptors, providing a spectroscopic handle to evaluate the functionalization. An initial coordination-driven self-assembly yields hexagonal metallacycles with alternating UPy and B21C7 groups at their vertices. The assembly does not interfere with H-bonding between the UPy groups, which link the discrete metallacycles into a supramolecular network, leaving the B21C7 groups free for functionalization via host-guest chemistry. The resultant network results in a cavity-cored metallogel at high concentrations or upon solvent swelling. The light-emitting properties of the dialkylammonium substrates were transferred to the network upon host-guest binding. This method is compatible with any dialkylammonium substrate that does not disrupt coordination nor H-bonding, and thus, the unification of these three orthogonal interactions represents a simple yet highly efficient strategy to obtain supramolecular polymeric materials with desirable functionality.

  5. Structures and stabilities of trivalent and tetravalent rare earth ions in sevenfold and eightfold coordination in fluorite-related complex oxides

    Energy Technology Data Exchange (ETDEWEB)

    Morss, L.R.

    1991-12-31

    This paper reports the preparation and characterization of a series of oxides containing 3+ or 4+ lanthanide (M = Ce, Pr, or Tb) ions, with different ionic sizes and varying M{sup 4+}/M{sup 3+} reduction potentials, in nearly cubic coordination. The objective of the study was to demonstrate how oxidation-reduction characteristics and ionic size trends explain the properties of these oxides and to compare the oxidation-reduction stability of M{sup 3+} and M{sup 4+} lanthanide ions in high (CN 7 or 8) coordination in fluorite-related oxides versus low (CN 6) coordination in perovskite oxides. Efficient preparative methods are reported, as well as powder diffraction and thermogravimetric measurements for oxides CaMTi{sub 2}O{sub 7-x} and CaMZr{sub 2}O{sub 7-x}. These oxides were characterized by X-ray powder diffraction and by thermogravimetric analysis. CaCeTi{sub 2}O{sub 7} is a pyrochlore, a = 10.142(4) {Angstrom}, with Ce{sup 4+} much more easily reducible than in the perovskite BaCeO{sub 3}. By contrast, a preparation with the stoichiometry ``CaPbTi{sub 2}O{sub 7-x}`` is a two-phase mixture-of perovskite CaTiCo{sub 3} and a presumably Pr{sup 3+}-rich pyrochlore Pr{sub 2}Ti{sub 2}O{sub 7}(?). CaTbTi{sub 2}O{sub 7-x} appears to be a Tb{sup 3+} pyrochlore, a = 10.149(2) {Angstrom}. CaCeZr{sub 2}O{sub 7} is a pyrochlore, a = 10.524(1) {Angstrom}. A preparation of ``CaPbZr{sub 2}O{sub 7-x}`` also appeared to yield a two-phase mixture, perovskite CaZrO{sub 3} and pyrochlore Pr{sub 2}Zr{sub 2}O{sub 7}. In this paper, the structures, f-element ion sites, and M(4)-M(3) stability trends in the CaMTi{sub 2}O{sub 7-x} and CaMZr{sub 2}O{sub 7-x} oxides are compared with the structural and stability trends in the perovskites BaMO{sub 3} which have M{sup 4+} ions in sixfold (tilted octahedra) coordination.

  6. Structures and stabilities of trivalent and tetravalent rare earth ions in sevenfold and eightfold coordination in fluorite-related complex oxides

    Energy Technology Data Exchange (ETDEWEB)

    Morss, L.R.

    1991-01-01

    This paper reports the preparation and characterization of a series of oxides containing 3+ or 4+ lanthanide (M = Ce, Pr, or Tb) ions, with different ionic sizes and varying M{sup 4+}/M{sup 3+} reduction potentials, in nearly cubic coordination. The objective of the study was to demonstrate how oxidation-reduction characteristics and ionic size trends explain the properties of these oxides and to compare the oxidation-reduction stability of M{sup 3+} and M{sup 4+} lanthanide ions in high (CN 7 or 8) coordination in fluorite-related oxides versus low (CN 6) coordination in perovskite oxides. Efficient preparative methods are reported, as well as powder diffraction and thermogravimetric measurements for oxides CaMTi{sub 2}O{sub 7-x} and CaMZr{sub 2}O{sub 7-x}. These oxides were characterized by X-ray powder diffraction and by thermogravimetric analysis. CaCeTi{sub 2}O{sub 7} is a pyrochlore, a = 10.142(4) {Angstrom}, with Ce{sup 4+} much more easily reducible than in the perovskite BaCeO{sub 3}. By contrast, a preparation with the stoichiometry CaPbTi{sub 2}O{sub 7-x}'' is a two-phase mixture-of perovskite CaTiCo{sub 3} and a presumably Pr{sup 3+}-rich pyrochlore Pr{sub 2}Ti{sub 2}O{sub 7}( ). CaTbTi{sub 2}O{sub 7-x} appears to be a Tb{sup 3+} pyrochlore, a = 10.149(2) {Angstrom}. CaCeZr{sub 2}O{sub 7} is a pyrochlore, a = 10.524(1) {Angstrom}. A preparation of CaPbZr{sub 2}O{sub 7-x}'' also appeared to yield a two-phase mixture, perovskite CaZrO{sub 3} and pyrochlore Pr{sub 2}Zr{sub 2}O{sub 7}. In this paper, the structures, f-element ion sites, and M(4)-M(3) stability trends in the CaMTi{sub 2}O{sub 7-x} and CaMZr{sub 2}O{sub 7-x} oxides are compared with the structural and stability trends in the perovskites BaMO{sub 3} which have M{sup 4+} ions in sixfold (tilted octahedra) coordination.

  7. Formation of a Six-Coordinate fac-[Re(Co)3]+ Complex by the N-C bond cleavage of a potentially tetradentate ligand

    International Nuclear Information System (INIS)

    The rhenium(I) compound fac-[Re(CO)3(daa)]. Hpab.H2O (Hpab N,N'-(l,2-phenylene)bis(2'-aminobenzamide); Hdaa 2-amino-N-(2-aminophenyl)benzamide) was synthesized from the reaction of [Re(CO)5,Br] with two equivalent of Hpab in toluene. The monoanionic tridentate ligand daa was formed by the rhenium-mediated cleavage of an amido N-C bond of the potentially tetradentate ligand Hpab. The compound was characterized by IR spectroscopy and X-ray crystallography, and daa is coordinated as a diamino amide via three nitrogen-donor atoms

  8. Alkali-metal ion coordination in uranyl(VI) poly-peroxide complexes in solution. Part 1: the Li⁺, Na⁺ and K⁺--peroxide-hydroxide systems.

    Science.gov (United States)

    Zanonato, Pier Luigi; Di Bernardo, Plinio; Vallet, Valerie; Szabó, Zoltán; Grenthe, Ingmar

    2015-01-28

    The alkali metal ions Li(+), Na(+) and K(+) have a profound influence on the stoichiometry of the complexes formed in uranyl(VI)-peroxide-hydroxide systems, presumably as a result of a templating effect, resulting in the formation of two complexes, M[(UO2)(O2)(OH)]2(-) where the uranyl units are linked by one peroxide bridge, μ-η(2)-η(2), with the second peroxide coordinated "end-on", η(2), to one of the uranyl groups, and M[(UO2)(O2)(OH)]4(3-), with a four-membered ring of uranyl ions linked by μ-η(2)-η(2) peroxide bridges. The stoichiometry and equilibrium constants for the reactions: M(+) + 2UO2(2+) + 2HO2(-) + 2H2O → M[(UO2)(O2)(OH)]2(-) + 4H(+) (1) and M(+) + 4UO2(2+) + 4HO2(-) + 4H2O → M[(UO2)(O2)(OH)]4(3-) + 8H(+) (2) have been measured at 25 °C in 0.10 M (tetramethyl ammonium/M(+))NO3 ionic media using reaction calorimetry. Both reactions are strongly enthalpy driven with large negative entropies of reaction; the observation that ΔH(2) ≈ 2ΔH(1) suggests that the enthalpy of reaction is approximately the same when peroxide is added in bridging and "end-on" positions. The thermodynamic driving force in the reactions is the formation of strong peroxide bridges and the role of M(+) cations is to provide a pathway with a low activation barrier between the reactants and in this way "guide" them to form peroxide bridged complexes; they play a similar role as in the synthesis of crown-ethers. Quantum chemical (QC) methods were used to determine the structure of the complexes, and to demonstrate how the size of the M(+)-ions affects their coordination geometry. There are several isomers of Na[(UO2)(O2)(OH)]2(-) and QC energy calculations show that the ones with a peroxide bridge are substantially more stable than the ones with hydroxide bridges. There are isomers with different coordination sites for Na(+) and the one with coordination to the peroxide bridge and two uranyl oxygen atoms is the most stable one.

  9. 基于区间不确定性水资源复杂系统的协调演化研究%Study on coordination evolvement of complex water resources system with interval uncertainty

    Institute of Scientific and Technical Information of China (English)

    韩雁; 黄跃飞; 王光谦; 王丽珍

    2011-01-01

    水资源系统是具有不确定性的复杂系统。本文通过分析水资源系统的复杂性与不确定性,构建了基于区间不确定条件下的水资源复杂系统协调演化分析方法。在利用主成分分析法得到子系统综合发展水平的基础上,采用系统的协调性指数模型来揭示系统间的相互关系,然后根据系统的信息熵得到其协调有序度,以此来反映水资源复杂系统的演化规律。以大连市为例的应用研究表明,观真实地揭示水资源复杂系统的演化区间及其发展趋势,指导意义。基于区间不确定性的水资源复杂系统协调演化,能够客对于实现区域水资源和社会经济的可持续发展具有重要指导意义。%Water resources system is a kind of complex system with great uncertainties. In this paper, a methodology for analyzing coordination degree of complex and uncertainty characteristics of water resources system is proposed. Based on interval uncertainty, a comprehensive development level of each subsystem in a water resources system with interval parameters could be obtained by using the Principal Component Analysis method. Then the mutual relationships between subsystems are obtained by using coordination exponent method. Finally, the order degree is determined by using information entropy to reveal the coordinated evolvement of complex water resources system. Such method has been applied to Dalian City and the resuits indicate that the coordinated evolvement of water resources system under uncertainty could objectively and factually reflect the evolutional interval and trend of a complex water resources system, which is important to decision-making for sustainable development of water resources and socio-economy.

  10. Coordinated bifluoride ions in the first thiofluoride molybdenum triangular cluster complex: synthesis and crystal structure of K5[Mo3S4F7(FHF)2]·2H2O

    Science.gov (United States)

    Mironov, Yu. V.; Yarovoi, S. S.; Solodovnikov, S. F.; Fedorov, V. E.

    2003-08-01

    The first triangular thiofluoride cluster complex of molybdenum K5[Mo3S4F7(FHF)2]·2H2O with unexpected coordination of bifluoride ions has been synthesized by the reaction of Mo3S7Br4 with molten KHF2. The compound was characterized by single crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Cmc21 with four formulas in unit cell of dimensions a=15.1060(20) Å,b=8.7820(9) Å,c=14.3358(13) Å,V=1901.8(4) Å3.

  11. 113Cd Shielding Tensors of Monomeric Cadmium Compounds Containing Nitrogen Donor Atoms. 3. CP/MAS Studies on Five-Coordinate Cadmium Complexes Having N(3)X(2) (X = H, N, O, and S) Donor Atoms.

    Science.gov (United States)

    Lipton, Andrew S.; Mason, Scott S.; Myers, Sheila M.; Reger, Daniel L.; Ellis, Paul D.

    1996-11-20

    The principal elements of the (113)Cd shielding tensor for a set of five- coordinate compounds having mixed donor atoms coordinating to the cadmium were determined via CP/MAS NMR experiments. The first complex, [HB(3,5-Me(2)pz)(3)]CdBH(4) (where pz = pyrazolyl), has a CdN(3)H(2) inner coordination sphere. The isotropic chemical shift in the solid state is 355.1 ppm, and its chemical shift anisotropy (CSA, Deltasigma) is -596 ppm with an asymmetry parameter (eta) of 0.64. The second complex, [HB(3,5-Me(2)pz)(3)]Cd[H(2)B(pz)(2)], has five nitrogen donor atoms bonded to the cadmium. This N(5) or N(3)N(2) compound was the only material of this study to manifest dipolar splitting of the cadmium resonance from the quadrupolar (14)N. The isotropic chemical shift, CSA, and the value of eta for this material were therefore determined at higher field where the dipolar splitting was less than the linewidth, yielding values of 226.6 ppm, -247 ppm, and 0.32, respectively. A second N(5) material, [HB(3-Phpz)(3)]Cd[H(2)B(3,5-Me(2)pz)(2)], was also investigated and has an isotropic shift of 190.2 ppm, a CSA of 254 ppm, and an eta of 0.86. Also studied was [HB(3-Phpz)(3)]Cd[(Bu(t)CO)(2)CH], which has an CdN(3)O(2) inner core. The isotropic chemical shift of this complex is 173.6 ppm, and the values of Deltasigma and eta were determined to be -258 ppm and 0.38, respectively. The final compound, [HB(3,5-Me(2)pz)(3)]Cd[S(2)CNEt(2)], with N(3)S(2) donor atoms, has an isotropic shift of 275.8 ppm, an eta of 0.51, and a CSA of +375 ppm. Utilizing previous assignments, the most shielded tensor element was determined to be oriented normal to the plane of the tridentate ligand. The shielding tensor information is used to speculate on the coordination geometry of the CdN(3)O(2) inner core complex. PMID:11666894

  12. Mononuclear thiocyanate containing nickel(II) and binuclear azido bridged nickel(II) complexes of N4-coordinate pyrazole based ligand: Syntheses, structures and magnetic properties

    Science.gov (United States)

    Solanki, Ankita; Monfort, Montserrat; Kumar, Sujit Baran

    2013-10-01

    Two mononuclear nickel(II) complexes [NiL1(NCS)2] (1) and [NiL2(NCS)2] (2) and two azido bridged binuclear nickel(II) complexes [Ni(()2()2] (3) and [Ni(()2()2] (4), where L1, L2, L1‧ and L2‧ are N,N-diethyl-N‧,N‧-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine (L1), N,N-bis((1H-pyrazol-1-yl)methyl)-N‧,N‧-diethylethane-1,2-diamine (L2), N,N-diethyl-N‧-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine (L1‧) and N-((1H-pyrazol-1-yl)methyl)-N‧,N‧-diethylethane-1,2-diamine (L2‧) have been synthesized and characterized by microanalyses and physico-chemical methods. Single crystal X-ray diffraction analyses revealed that complexes 1 and 2 are mononuclear NCS- containing Ni(II) complex with octahedral geometry and complexes 3 and 4 are end-on (μ-1,1) azido bridged binuclear Ni(II) complexes with distorted octahedral geometry. Variable temperature magnetic studies of the complexes 3 and 4 display ferromagnetic interaction with J values 19 and 32 cm-1, respectively.

  13. Synthesis, chemistry, and catalytic activity of complexes of lanthanide and actinide metals in unusual oxidation states and coordination environments. Progress report, February 1, 1981-January 31, 1982

    International Nuclear Information System (INIS)

    The objectives of this research project are: (1) to demonstrate experimentally that the lanthanide and actinide metals have a more extensive chemistry than is presently known; (2) to develop a better understanding of the special features of the f orbital elements which will allow the design of f orbital complexes possessing unique chemical and physical properties; (3) to provide a basis for seeking unusual catalytic transformations involving these elements; and (4) to synthesize and explore the chemical and physical properties of mixed metal complexes which contain both lanthanide and transition metals. During the past year progress was made in each area. Some of the specific results are: (1) the first activation of CO by an organolanthanide complex was demonstrated; (2) the first, crystallograhically characterized, molecular lanthanide hydride complexes, the bridged dimers, [(C5H4R)2LnH(THF)]2 (R=H, CH3; Ln=Lu, Er, Y), were synthesized by hydrogenolysis of the appropriate (C5H4R)2Ln(C(CH3)3)(THF) complex; (3) [(C5H5)2(THF)ErH]2 was found to catalyze the homogeneous hydrogenation of alkynes; (4) the first trimetallic organolanthanide complex was synthesized; (5) the first polyhydridic organolanthanide complex was synthesized; (6) U(III) hydride was found to catalytically activate molecular hydrogen in alkene and alkyne hydrogenation reactions

  14. RME-8 coordinates the activity of the WASH complex with the function of the retromer SNX dimer to control endosomal tubulation

    OpenAIRE

    Freeman, Caroline L.; Hesketh, Geoffrey; Seaman, Matthew N J

    2014-01-01

    Retromer is a vital element of the endosomal protein sorting machinery and comprises two subcomplexes that operate together to sort membrane proteins (cargo) and tubulate membranes. Tubules are formed by a dimer of sorting nexins, a key component of which is SNX1. Cargo selection is mediated by the VPS35–VPS29–VPS26 trimer, which additionally recruits the WASH complex through VPS35 binding to the WASH complex subunit FAM21. Loss of function of the WASH complex leads to dysregulation of endoso...

  15. catena-Poly[[di-μ2-aqua-hexaaquabis(μ3-4-oxidopyridine-2,6-dicarboxylato)trimanganese(II)] trihydrate]: a new one-dimensional coordination polymer based on a trinuclear Mn(II) complex of chelidamic acid.

    Science.gov (United States)

    Mirzaei, Masoud; Eshtiagh-Hosseini, Hossein; Karrabi, Zahra; Notash, Behrouz

    2013-10-01

    4-Hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid, hypydc[H]H2) reacts with MnCl2·2H2O in the presence of piperazine in water to afford the title complex, {[Mn3(C7H2NO5)2(H2O)8]·3H2O}n or {[Mn3(hypydc)2(H2O)8]·3H2O}n. This compound is a one-dimensional coordination polymer, with the twofold symmetric repeat unit containing three metal centres. Two different coordination geometries are observed for the two independent Mn(II) metal centres, viz. a distorted pentagonal bipyramid and a distorted octahedron. The 4-oxidopyridine-2,6-dicarboxylate anions and two of the water molecules act as bridging ligands. The zigzag-like geometry of the coordination polymer is stabilized by hydrogen bonds. O-H···O and C-H···O hydrogen bonds and water clusters consolidate the three-dimensional network structure.

  16. Effect of applied hydrostatic pressure on the quenching kinetics, and electronic and molecular structure of eight and nine-coordinate lanthanide complexes in solution

    International Nuclear Information System (INIS)

    Full text: Applied hydrostatic pressure may be used as a probe of the reaction mechanism for various solution reactions involving lanthanide ions. In this work we report on the use of high pressure to probe the mechanism of enantioselective quenching between racemic luminescent lanthanide complexes containing Dy(III) Tb(III) and Eu(III), and optically active transition metal complexes as quenchers. Diastereomeric rate constants are obtained from a biexponential fit of the luminescence decay. Particular attention will be given to solvation effects on the measured diastereomeric rate constants. The source of chirality is ascribed to a enantioselective rearrangement step within a bimolecular 'encounter' complex yielding a intermolecular geometry in which the energy transfer is efficient. The effect of high pressure on the molecular and electronic structure of these complexes will also be discussed

  17. A molecular orbital study of a model of the Mg2+ coordination complex of the self splicing reaction of ribosomal RNA

    Science.gov (United States)

    McCourt, M.; Shibata, M.; McIver, J. W.; Rein, R.

    1988-01-01

    Recent discoveries have established the fact that RNA is capable of acting as an enzyme. In this study two different types of molecular orbital calculations, INDO and ab initio, were used in an attempt to assess the structural/functional role of the Mg2+ hydrated complex in ribozyme reactions. Preliminary studies indicate that the reaction is multistep and that the Mg2+ complex exerts a stabilizing effect on the intermediate or midpoint of the reaction.

  18. Complexes With Biologically Active Ligands. Part 4. Coordination Compounds of Chlorothiazide With Transition Metal Ions Behave as Strong Carbonic Anhydrase Inhibitors

    OpenAIRE

    Supuran, Claudiu T.

    1996-01-01

    Complexes of the diuretic benzothiadiazine derivative chlorothiazide (6-chloro-7-sulfamoyl- 1,2,4-benzothiadiazine-1,1-dioxide) with V(IV); Fe(II); Co(II); Ni(II); Cu(II), Ag(I) and U(VI) were prepared and characterized by elemental analysis, spectroscopic, thermogravimetric, magnetic and conductimetric measurements. The complexes behave as effective inhibitors for two isozymes (I and II) of carbonic anhydrase (CA).

  19. RUN COORDINATION

    CERN Document Server

    C. Delaere

    2013-01-01

    Since the LHC ceased operations in February, a lot has been going on at Point 5, and Run Coordination continues to monitor closely the advance of maintenance and upgrade activities. In the last months, the Pixel detector was extracted and is now stored in the pixel lab in SX5; the beam pipe has been removed and ME1/1 removal has started. We regained access to the vactank and some work on the RBX of HB has started. Since mid-June, electricity and cooling are back in S1 and S2, allowing us to turn equipment back on, at least during the day. 24/7 shifts are not foreseen in the next weeks, and safety tours are mandatory to keep equipment on overnight, but re-commissioning activities are slowly being resumed. Given the (slight) delays accumulated in LS1, it was decided to merge the two global runs initially foreseen into a single exercise during the week of 4 November 2013. The aim of the global run is to check that we can run (parts of) CMS after several months switched off, with the new VME PCs installed, th...

  20. RUN COORDINATION

    CERN Multimedia

    Christophe Delaere

    2013-01-01

    The focus of Run Coordination during LS1 is to monitor closely the advance of maintenance and upgrade activities, to smooth interactions between subsystems and to ensure that all are ready in time to resume operations in 2015 with a fully calibrated and understood detector. After electricity and cooling were restored to all equipment, at about the time of the last CMS week, recommissioning activities were resumed for all subsystems. On 7 October, DCS shifts began 24/7 to allow subsystems to remain on to facilitate operations. That culminated with the Global Run in November (GriN), which   took place as scheduled during the week of 4 November. The GriN has been the first centrally managed operation since the beginning of LS1, and involved all subdetectors but the Pixel Tracker presently in a lab upstairs. All nights were therefore dedicated to long stable runs with as many subdetectors as possible. Among the many achievements in that week, three items may be highlighted. First, the Strip...

  1. 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.

  2. Synthesis, molecular and electronic structures of six-coordinate transition metal (Mn, Fe, Co, Ni, Cu, and Zn) complexes with redox-active 9-hydroxyphenoxazin-1-one ligands.

    Science.gov (United States)

    Ivakhnenko, Eugeny P; Starikov, Andrey G; Minkin, Vladimir I; Lyssenko, Konstantin A; Antipin, Mikhail Yu; Simakov, Vladimir I; Korobov, Mikhail S; Borodkin, Gennady S; Knyazev, Pavel A

    2011-08-01

    A series of pseudo-octahedral metal (M = Mn, Fe, Co, Ni, Cu, Zn) complexes 4 of a new redox-active ligand, 2,4,6,8-tetra(tert-butyl)-9-hydroxyphenoxazin-1-one 3, have been synthesized, and their molecular structures determined with help of X-ray crystallography. The effective magnetic moments of complexes 4 (M = Mn, Fe, Co, and Ni) measured in the solid state and toluene solution point to the stabilization of their high-spin electronic ground states. Detailed information on the electronic structure of the complexes and their redox-isomeric forms has been obtained using density functional theory (DFT) B3LYP*/6-311++G(d,p) calculations. The energy disfavored low-spin structures of manganese, iron, and cobalt complexes have been located, and based on the computed geometries and distribution of spin densities identified as Mn(IV)[(Cat-N-SQ)](2), Fe(II)[Cat-N-BQ)](2), and Co(II)[Cat-N-BQ)](2) compounds, respectively. It has been shown that stabilization of the high-spin structures of complexes 4 (M = Mn, Fe, Co) is caused by the rigidity of the molecular framework of ligands 3 that sterically inhibits interconversions between the redox-isomeric forms of the complexes. The calculations performed on complex 4 (M = Co) predict that a suitable structural modification that might provide for stabilization of the low-spin electromeric forms and create conditions for the valence tautomeric rearrangement via stabilization of the low-spin electromer and narrowing energy gap between the low-spin ground state tautomer and the minimal energy crossing point on the intersection of the potential energy surfaces of the interconverting structures consists in the replacement of an oxygen in the oxazine ring by a bulkier sulfur atom. PMID:21718042

  3. Coordination chemistry of two heavy metals: I, Ligand preferences in lead(II) complexation, toward the development of therapeutic agents for lead poisoning: II, Plutonium solubility and speciation relevant to the environment

    International Nuclear Information System (INIS)

    The coordination chemistry and solution behavior of the toxic ions lead(II) and plutonium(IV, V, VI) have been investigated. The ligand pKas and ligand-lead(II) stability constants of one hydroxamic acid and four thiohydroaxamic acids were determined. Solution thermodynamic results indicate that thiohydroxamic acids are more acidic and slightly better lead chelators than hydroxamates, e.g., N-methylthioaceto-hydroxamic acid, pKa = 5.94, logβ120 = 10.92; acetohydroxamic acid, pKa = 9.34, logβl20 = 9.52. The syntheses of lead complexes of two bulky hydroxamate ligands are presented. The X-ray crystal structures show the lead hydroxamates are di-bridged dimers with irregular five-coordinate geometry about the metal atom and a stereochemically active lone pair of electrons. Molecular orbital calculations of a lead hydroxamate and a highly symmetric pseudo octahedral lead complex were performed. The thermodynamic stability of plutonium(IV) complexes of the siderophore, desferrioxamine B (DFO), and two octadentate derivatives of DFO were investigated using competition spectrophotometric titrations. The stability constant measured for the plutonium(IV) complex of DFO-methylterephthalamide is logβ110 = 41.7. The solubility limited speciation of 242Pu as a function of time in near neutral carbonate solution was measured. Individual solutions of plutonium in a single oxidation state were added to individual solutions at pH = 6.0, T = 30.0, 1.93 mM dissolved carbonate, and sampled over intervals up to 150 days. Plutonium solubility was measured, and speciation was investigated using laser photoacoustic spectroscopy and chemical methods

  4. Coordination chemistry of two heavy metals: I, Ligand preferences in lead(II) complexation, toward the development of therapeutic agents for lead poisoning: II, Plutonium solubility and speciation relevant to the environment

    Energy Technology Data Exchange (ETDEWEB)

    Neu, M.P. [Lawrence Berkeley Lab., CA (United States)

    1993-11-01

    The coordination chemistry and solution behavior of the toxic ions lead(II) and plutonium(IV, V, VI) have been investigated. The ligand pK{sub a}s and ligand-lead(II) stability constants of one hydroxamic acid and four thiohydroaxamic acids were determined. Solution thermodynamic results indicate that thiohydroxamic acids are more acidic and slightly better lead chelators than hydroxamates, e.g., N-methylthioaceto-hydroxamic acid, pK{sub a} = 5.94, log{beta}{sub 120} = 10.92; acetohydroxamic acid, pK{sub a} = 9.34, log{beta}{sub l20} = 9.52. The syntheses of lead complexes of two bulky hydroxamate ligands are presented. The X-ray crystal structures show the lead hydroxamates are di-bridged dimers with irregular five-coordinate geometry about the metal atom and a stereochemically active lone pair of electrons. Molecular orbital calculations of a lead hydroxamate and a highly symmetric pseudo octahedral lead complex were performed. The thermodynamic stability of plutonium(IV) complexes of the siderophore, desferrioxamine B (DFO), and two octadentate derivatives of DFO were investigated using competition spectrophotometric titrations. The stability constant measured for the plutonium(IV) complex of DFO-methylterephthalamide is log{beta}{sub 110} = 41.7. The solubility limited speciation of {sup 242}Pu as a function of time in near neutral carbonate solution was measured. Individual solutions of plutonium in a single oxidation state were added to individual solutions at pH = 6.0, T = 30.0, 1.93 mM dissolved carbonate, and sampled over intervals up to 150 days. Plutonium solubility was measured, and speciation was investigated using laser photoacoustic spectroscopy and chemical methods.

  5. A new PC(sp(3))P ligand and its coordination chemistry with low-valent iron, cobalt and nickel complexes.

    Science.gov (United States)

    Zhu, Gengyu; Li, Xiaoyan; Xu, Guoqiang; Wang, Lin; Sun, Hongjian

    2014-06-21

    A new PC(sp(3))P ligand N,N'-bis(diphenylphosphino)dipyrromethane [PCH2P] (1) was prepared and its iron, cobalt and nickel chemistry was explored. Two pincer-type complexes [PCHP]Fe(H)(PMe3)2 (2) and [PCHP]Co(PMe3)2 (4) were synthesized in the reaction of with Fe(PMe3)4 and Co(Me)(PMe3)4. 1 reacted with Co(PMe3)4 and Ni(PMe3)4 to afford Co(0) and Ni(0) complexes [PCH2P]Co(PMe3)2 (3) and [PCH2P]Ni(PMe3)2 (5). The structures of complexes 2-5 were determined by X-ray diffraction.

  6. Probing the lowest coordination number of dianionic platinum-cyanide complexes in the gas phase: Dynamics of the charge dissociation process

    DEFF Research Database (Denmark)

    Bojesen, G; Hvelplund, P; Jørgensen, Thomas J. D.;

    2000-01-01

    Low-energy and high-energy collision induced dissociation techniques are used to study the dissociation behavior of the gaseous Pt(CN)(6)(2-) and Pt(CN)(4)(2-) dianion complexes in order to probe the smallest stable dianion complex. Loss of neutral molecules from Pt(CN)(6)(2-) occurs resulting...... in Pt(CN)(5)(2-) and Pt(CN)(4)(2-), but no indication of the existence of Pt(CN)(3)(2-) was found. This indicates that the lifetime of Pt(CN)(3)(2-) is less than 4 mus (the flight time from the collision region to the detector). In contrast, all monoanion platinum-cyanide complexes were observed, i...

  7. Synthesis, Spectral and Thermal Properties of Some Penta-Coordinated Complexes of Oxovanadium(IV) Derived from Thiosemicarbazones of 4-Aminoantipyrine

    OpenAIRE

    Ram K. Agarwal; PRASAD, Surendra; GAHLOT, Neetu

    2004-01-01

    The paper reports the synthesis of crystalline oxovanadium(IV), VO2+, complexes of thiosemicarbazones, i.e. 4[N-(4'-nitrobenzalidene)amino]antipyrine thiosemicarbazone (4'-NO2BAAPTS) and 4[N-(furan-2'-aldimine)amino]antipyrine thiosemicarbazone (FFAAPTS) with general composition VOX2L (X = Cl, Br, I, NO3 or NCS) and VO(ClO4)2(L)H2O (L = 4'-NO2BAAPTS or FFAAPTS). All the complexes were characterized by elemental analyses, molar mass, molar conductance, magnetic susc...

  8. Characteristics of Trivalent Lanthanides in Coordination Chemistry

    Institute of Scientific and Technical Information of China (English)

    Xue Dongfeng(薛冬峰); Zuo Sen(左森); Henryk Ratajczak

    2004-01-01

    Some basic characteristics of lanthanide-oxygen bonds in various trivalent lanthanide metal-organic complexes are quantitatively studied by the bond valence model. Some important relationships among the electronegativity, bond valence parameter, bond length and lanthanide coordination number in these complexes are generally found , which show that for each trivalent lanthanide cation all calculated parameters may well be correlated with its coordination number in their coordination complexes. Specifically,32 new data for the bond valence parameter are first calculated in this work.An approximate linear relationship between the Ln-O bond valence parameter and the coordination number of Ln3+ is obtained.The Ln-O bond length increases with the increase in the lanthanide coordination number.The difference of electronegative values decreases with the increase in the lanthanide coordination number.

  9. Self-assembly of extended structures through non-coordination intermolecular forces: Synthesis, crystal structures, and properties of metal complexes with 5-methyl-2-pyrazinecarboxylate

    NARCIS (Netherlands)

    Tanase, S.; Son, M. van; Albada, G.A. van; Gelder, R. de; Bouwman, E.; Reedijk, J.

    2006-01-01

    Three new complexes of 5-methyl-2-pyrazinecarboxylate (Hmpca) with cobalt(II), [Co(mpca)(2)(H2O)(2)], nickel(II), [Ni(mpca)(2)(H2O)(2)] and iron(III) [Fe(mpca)(2)(OH)](2) center dot 2H(2)O, have been synthesized and characterized by spectroscopic techniques, X-ray crystallography and low-temperature

  10. Synthesis, spectroscopic characterization and X-ray structures of five-coordinate diorganotin(IV) complexes containing 5-hydroxypyrazoline derivatives as ligands

    Science.gov (United States)

    Sousa, Gerimário F. de; Garcia, Edgardo; Gatto, Claudia C.; Resck, Inês S.; Deflon, Victor M.; Ardisson, José D.

    2010-09-01

    Four new diorganotin(IV) complexes have been prepared from R 2SnCl 2 (R = Me, Ph) with the ligands 5-hydroxy-3-metyl-5-phenyl-1-( S-benzildithiocarbazate)-pyrazoline (H 2L 1) and 5-hydroxy-3-methyl-5-phenyl-1-(2-thiophenecarboxylic)-pyrazoline (H 2L 2). The complexes were characterized by elemental analysis, IR, 1H, 13C, 119Sn NMR and Mössbauer spectroscopies. The complexes [Me 2SnL 1], [Ph 2SnL 1] and [Me 2SnL 2] were also studied by single crystal X-ray diffraction and the results showed that the Sn(IV) central atom of the complexes adopts a distorted trigonal bipyramidal (TBP) geometry with the N atom of the ONX-tridentate (X = O and S) ligand and two organic groups occupying equatorial sites. The C-Sn-C angles for [Me 2Sn(L 1)] and [Ph 2Sn(L 1)] were calculated using a correlation between 119Sn Mössbauer and X-ray crystallographic data based on the point-charge model. Theoretical calculations were performed with the B3LYP density functional employing 3-21G(*) and DZVP all electron basis sets showing good agreement with experimental findings. General and Sn(IV) specific IR harmonic frequency scale factors for both basis sets were obtained from comparison with selected experimental frequencies.

  11. Synthesis and photophysical studies of chiral helical macrocyclic scaffolds via coordination-driven self-assembly of 1,8,9,16-tetraethynyltetraphenylene. formation of monometallic platinum(II) and dimetallic platinum(II)-ruthenium(II) complexes.

    Science.gov (United States)

    Lin, Fang; Peng, Hai-Yan; Chen, Jing-Xing; Chik, David T W; Cai, Zongwei; Wong, Keith M C; Yam, Vivian W W; Wong, Henry N C

    2010-11-24

    This paper is concerned with the synthesis and reactions of enantiopure 1,8,9,16-tetraethynyltetraphenylene (3). We obtained 3 in 34% yield through four steps starting from 1,8,9,16-tetrahydroxytetraphenylene (2a) via a functional group interconversion strategy. On the basis of this chiral "helical" building block, three rigid helical macrocycles 14, 15, and 22 were designed. Complexes 14 and 15 were constructed via coordination-driven self-assembly with platinum(II) complexes 8 and 9b, while 22 cannot be obtained successfully. Then macrocycle 28 was designed on the structural basis of 22 to which octyl chains were introduced, in the hope of improving the solubility of the complex. Macrocycle 28 was finally formed and was characterized by NMR spectroscopy, elemental analysis, and electrospray mass spectrometry. For the enantiopure 15 and 28, circular dichroism (CD) spectra also exhibited chiral properties. Complexes 27 and 28 both exhibited an intense emission band at 621 nm in acetonitrile at 298 K upon excitation at λ > 420 nm. PMID:21033663

  12. Doubly TEMPO-coordinated gadolinium(III), lanthanum(III), and yttrium(III) complexes. Strong superexchange coupling across rare earth ions.

    Science.gov (United States)

    Murakami, Rina; Nakamura, Takeshi; Ishida, Takayuki

    2014-04-21

    We prepared crystalline [RE(III)(hfac)3(TEMPO)2] (RE = Gd, La, Y), where TEMPO and hfac stand for 2,2,6,6-tetramethylpiperidin-1-oxyl and 1,1,1,5,5,5-hexafluoropentane-2,4-dionate, respectively. The X-ray crystal structure of TEMPO-coordinated RE compounds was determined for the first time. The Gd and Y analogues are isomorphous, and the La derivative has a similar molecular skeleton. The Gd-O(TEMPO) bond lengths were 2.322(3) and 2.354(3) Å with the O-Gd-O angle of 140.36(11)°. The magnetic study clarified that [Gd(hfac)3(TEMPO)2] behaved as a ground Stotal = 7/2 species. The La and Y analogues showed the superexchange interactions across the diamagnetic ions with 2JTEMPO1-TEMPO2/kB = -14.9(1) and -49.8(2) K, respectively. Assuming the presence of a similar interaction like the Y derivative, the Gd-TEMPO exchange couplings are estimated with 2JGd-TEMPO/kB = -12.9(5) and +8.0(6) K.

  13. Bridged bis(beta-cyclodextrin)s possessing coordinated metal center(s) and their inclusion complexation behavior with model substrates: enhanced molecular binding ability by multiple recognition.

    Science.gov (United States)

    Liu, Y; Chen, Y; Li, L; Zhang, H Y; Liu, S X; Guan, X D

    2001-12-14

    To investigate quantitatively the cooperative binding ability of several beta-cyclodextrin oligomers bearing single or multiligated metal center(s), the inclusion complexation behavior of four bis(beta-cyclodextrin)s (2-5) linked by 2,2'-bipyridine-4,4'-dicarboxy tethers and their copper(II) complexes (6-9) with representative dye guests, i.e., methyl orange (MO), acridine red (AR), rhodamine B (RhB), ammonium 8-anilino-1-naphthalenesulfonic acid (ANS), and sodium 6-(p-toludino)-2-naphthalenesulfonate (TNS), have been examined in aqueous solution at 25 degrees C by means of UV-vis, circular dichroism, fluorescence, and 2D NMR spectroscopy. The results obtained indicate that bis(beta-cyclodextrin)s 2-5 can associate with one or three copper(II) ion(s) producing 2:1 or 2:3 bis(beta-cyclodextrin)-copper(II) complexes. These metal-ligated oligo(beta-cyclodextrin)s can bind two model substrates to form intramolecular 2:2 host-guest inclusion complexes and thus significantly enhance the original binding abilities of parent beta-cyclodextrin and bis(beta-cyclodextrin) toward model substrates through the cooperative binding of two guest molecules by four tethered cyclodextrin moieties, as well as the additional binding effect supplied by ligated metal center(s). Host 6 showed the highest enhancement of the stability constant, up to 38.3 times for ANS as compared with parent beta-cyclodextrin. The molecular binding mode and stability constant of substrates by bridged bis- and oligo(beta-cyclodextrin)s 2-9 are discussed from the viewpoint of the size/shape-fit interaction and molecular multiple recognition between host and guest.

  14. Binding of hydrocarbons and other extremely weak ligands to transition metal complexes that coordinate hydrogen: Investigation of cis-interactions and delocalized bonding involving sigma bonds

    Energy Technology Data Exchange (ETDEWEB)

    Kubas, G.J.; Eckert, J.; Luo, X.L. [and others

    1997-07-01

    This is the final report of a three-year Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). At the forefront of chemistry are efforts to catalytically transform the inert C-H bonds in alkanes to more useful products using metal compounds. The goal is to observe binding and cleavage of alkane C-H bonds on metals or to use related silane Si-H bonding as models, analogous to the discovery of hydrogen (H{sub 2}) binding to metals. Studies of these unique sigma complexes (M{hor_ellipsis}H-Y; Y{double_bond}H, Si, C) will aid in developing new catalysts or technologies relevant to DOE interest, e.g., new methods for tritium isotope separation. Several transition metals (Mo, W, Mn, and Pt) were found to reversibly bind and cleave H{sub 2}, silanes, and halocarbons. The first metal-SiH{sub 4} complexes, thus serving as a model for methane reactions. A second goal is to study the dynamics and energetics of H-Y bonds on metals by neutron scattering, and evidence for interactions between bound H-Y and nearby H atoms on metal complexes has been found.

  15. Estimation of coordination complex structure of O Cu(I) 2-aminopyrimidine on a copper surface using X-ray photoelectron spectroscopy

    Science.gov (United States)

    Miao, Qiang; Yie, Xiangrong; Xin, Xinquan; Adachi, Hirohiko; Tanaka, Iso

    2001-02-01

    XPS spectra for cleaned and a 2-aminopyrimidine treated copper plates have been measured from 0.0 to about 1000.0 eV. The spectral features of Cu 2p3/2 and O 1s peaks indicate Cu 2O layer formation on the copper surface. High resolution N 1s XPS spectra recorded for free 2-aminopyrimidine and 2-aminopyrimidine treated copper films indicate that 2-aminopyrimidine reacts with the copper surface forming a [O-Cu(I)-2-AP] complex on an oxidized underlayer. First principles molecular orbital calculations have been performed on an embedded model of 2-aminopyrimidine and on eight assumed surface model cluster complexes. The N 1s level in 2-aminopyrimidine is quantitatively well reproduced. Spectral features within 28 eV of the edge as well as absolute energies are satisfactorily reproduced by the ground state calculation using a minimal basis set. The [O-Cu(I)-2-AP] surface models show theoretical spectra of Cu(I)-pyrimidine ring π-complexes that agree well with the high resolution N 1s XPS data.

  16. (15)N NMR spectroscopy unambiguously establishes the coordination mode of the diimine linker 2-(2'-pyridyl)pyrimidine-4-carboxylic acid (cppH) in Ru(ii) complexes.

    Science.gov (United States)

    Battistin, Federica; Balducci, Gabriele; Demitri, Nicola; Iengo, Elisabetta; Milani, Barbara; Alessio, Enzo

    2015-09-21

    We investigated the reactivity of three Ru(ii) precursors -trans,cis,cis-[RuCl2(CO)2(dmso-O)2], cis,fac-[RuCl2(dmso-O)(dmso-S)3], and trans-[RuCl2(dmso-S)4] - towards the diimine linker 2-(2'-pyridyl)pyrimidine-4-carboxylic acid (cppH) or its parent compound 4-methyl-2-(2'-pyridyl)pyrimidine ligand (mpp), in which a methyl group replaces the carboxylic group on the pyrimidine ring. In principle, both cppH and mpp can originate linkage isomers, depending on how the pyrimidine ring binds to ruthenium through the nitrogen atom ortho (N(o)) or para (N(p)) to the group in position 4. The principal aim of this work was to establish a spectroscopic fingerprint for distinguishing the coordination mode of cppH/mpp also in the absence of an X-ray structural characterization. By virtue of the new complexes described here, together with the others previously reported by us, we successfully recorded {(1)H,(15)N}-HMBC NMR spectra at natural abundance of the (15)N isotope on a consistent number of fully characterized Ru(ii)-cppH/mpp compounds, most of them being stereoisomers and/or linkage isomers. Thus, we found that (15)N NMR chemical shifts unambiguously establish the binding mode of cppH and mpp - either through N(o) or N(p)- and can be conveniently applied also in the absence of the X-ray structure. In fact, coordination of cppH to Ru(ii) induces a marked upfield shift for the resonance of the N atoms directly bound to the metal, with coordination induced shifts (CIS) ranging from ca.-45 to -75 ppm, depending on the complex, whereas the unbound N atom resonates at a frequency similar to that of the free ligand. Similar results were found for the complexes of mpp. This work confirmed our previous finding that cppH has no binding preference, whereas mpp binds exclusively through N(p). Interestingly, the two cppH linkage isomers trans,cis-[RuCl2(CO)2(cppH-κN(p))] (5) and trans,cis-[RuCl2(CO)2(cppH-κN(o))] (6) were easily obtained in pure form by exploiting their different

  17. TECHNICAL COORDINATION

    CERN Multimedia

    A. Ball

    Shutdown critical path: progress and prospects The 2008-09 CMS shutdown is proceeding as intended.  The first two phases, in which the dominant activity (besides heavy logistics) was maintenance and repair of the barrel muon and alignment systems on all wheels and disks (but particularly YB0), have been finished successfully and on time. The yoke wheels at both ends are once again closed over the vactank. Phase 3 is in full swing and has reached maximum complexity, with work-intensity and associated risks similar those encountered in summer 2008. The status going into this CMS week is that the forward pixel tracker at the +z end (FPIX+) has been extracted and transported for maintenance, while the installation of preshower ES+, taking place in parallel, has reached the stage where the active “dee” elements are installed and the drum structures have just been moved back along the beampipe and re-mated to the electromagnetic endcaps. The phase 3 activity requires the large &l...

  18. Preparation and characterization of technetium complexes with Schiff base and phosphine coordination. 1. complexes of technetium-99g and -99m with substituted acac2en and trialkyl phosphines (where acac2en N,N'-ethylenebis[acetylacetone iminato])

    International Nuclear Information System (INIS)

    A series of 23 technetium(III) complexes of the type [TcL(PR3)2]+, where L represents a tetradentate Schiff base ligand in the equatorial plane and PR3 represents the axial phosphine ligands, are reported. Full ligand syntheses and characterizations are included. The technetium complexes were prepared with 99mTc to study the organ distribution in guinea pigs at 5 and 60 min postinjection. Four prototypical complexes of the series were also prepared with either 99gTc or 99gTc/99mTc (designated as carrier-added) to allow macroscopic characterization. Equivalence of the 99gTc and 99mTc complexes was demonstrated by dual detection high performance liquid chromatography (HPLC) techniques. The development of a one-step preparation from the standard two-step method is discussed for some complexes. Biodistribution data are related to structure and lipophilicity. None of the complexes in the series exhibited a tendency for in vivo reduction. Myocardial uptake was favorable for a number of complexes. The optimal agent from this series for further imaging development was chosen based on myocardial uptake, rapid blood and liver clearance, and ability to be formulated as a one-step kit

  19. Synthesis, structure and spectral properties of O,N,N coordinating ligands and their neutral Zn(ii) complexes: a combined experimental and theoretical study.

    Science.gov (United States)

    Hens, Amar; Mondal, Pallab; Rajak, Kajal Krishna

    2013-10-01

    Mononuclear Zn(ii) complexes with the general formula [Zn(L)2] have been synthesized in good yields by reacting Zn(OAc)2 with HL in a ratio of 1 : 2 in methanol solvent. Here L is the deprotonated form of 6-[(quinolin-8-ylamino)methylene]cyclohexa-2,4-dienone (HL(1)), 4-chloro-6-[(quinolin-8-ylamino)methylene]cyclohexa-2,4-dienone (HL(2)), 4-methyl-6-[(quinolin-8-ylamino)methylene]cyclohexa-2,4-dienone (HL(3)), 2,4-dimethyl-6-[(quinolin-8-ylamino) methylene]cyclohexa-2,4-dienone (HL(4)), 2-methoxy-6-[(quinolin-8-ylamino) methylene]cyclohexa-2,4-dienone (HL(5)). The electronic structures and photophysical properties of the ligands were calculated by DFT and TDDFT methods. The X-ray structure of one complex is reported. The ligands have a strong binding ability [(0.75-15.37) × 10(4)] and ratiometric response to Zn(2+) ions. With the addition of Zn(2+) ions to the ligands in THF solution a sharp color change is observed visually, and as well a significant enhancement of the fluorescence intensity and the quantum yield for this series occurs. The introduction of other metal ions having biological and environmental effects results in either unaltered or quenched emission intensity. However we observed the sensing property of the ligands strongly depends on the substituent at the ortho position of the phenol group. DFT calculation reveals that the ICT process take place from the salicylaldehyde (donor moiety) to quinoline (acceptor moiety) which is responsible for the enhancement of the fluorescence intensity of ligands after complexation. PMID:23995072

  20. Intramolecularly Stabilized 1,4-Phenylene-Bridged Homo- and Heterodinuclear Palladium and Platinum Organometallic Complexes Containing N,C,N-Coordination Motifs

    NARCIS (Netherlands)

    Koten, G. van; Steenwinkel, P.; Kooijman, H.; Smeets, W.J.J.; Spek, A.L.; Grove, D.M.

    1998-01-01

    The new ligand precursors [1-(Me3Si)-4-(R){C6(CH2NMe2)4-2,3,5,6}] (2, R = Me3Si; 3, R = H) have been used for the preparation of ionic 1,4-phenylene-bridged bispalladium(II) and palladium(II)-platinum(II) complexes [1-{M(MeCN)}-4-{M'(MeCN)}{C6(CH2NMe2)4-2,3,5,6}](BPh4)2 (5b, M = M' = Pd; 10, M = Pd,

  1. Late First-Row Transition-Metal Complexes Containing a 2-Pyridylmethyl Pendant-Armed 15-Membered Macrocyclic Ligand. Field-Induced Slow Magnetic Relaxation in a Seven-Coordinate Cobalt(II) Compound.

    Science.gov (United States)

    Antal, Peter; Drahoš, Bohuslav; Herchel, Radovan; Trávníček, Zdeněk

    2016-06-20

    The 2-pyridylmethyl N-pendant-armed heptadentate macrocyclic ligand {3,12-bis(2-methylpyridine)-3,12,18-triaza-6,9-dioxabicyclo[12.3.1]octadeca-1,14,16-triene = L} and [M(L)](ClO4)2 complexes, where M = Mn(II) (1), Fe(II) (2), Co(II) (3), Ni(II) (4), and Cu(II) (5), were prepared and thoroughly characterized, including elucidation of X-ray structures of all the compounds studied. The complexes 1-5 crystallize in non-centrosymmetric Sohncke space groups as racemic compounds. The coordination numbers of 7, 6 + 1, and 5 were found in complexes 1-3, 4, and 5, respectively, with a distorted pentagonal bipyramidal (1-4) or square pyramidal (5) geometry. On the basis of the magnetic susceptibility experiments, a large axial zero-field splitting (ZFS) was found for 2, 3, and 4 (D(Fe) = -7.4(2) cm(-1), D(Co) = 34(1) cm(-1), and D(Ni) = -12.8(1) cm(-1), respectively) together with a rhombic ZFS (E/D = 0.136(3)) for 4. Despite the easy plane anisotropy (D > 0, E/D = 0) in 3, the slow relaxation of the magnetization below 8 K was observed and analyzed either with Orbach relaxation mechanism (the relaxation time τ0 = 9.90 × 10(-10) s and spin reversal barrier Ueff = 24.3 K (16.9 cm(-1))) or with Raman relaxation mechanism (C = 2.12 × 10(-5) and n = 2.84). Therefore, compound 3 enlarges the small family of field-induced single-molecule magnets with pentagonal-bipyramidal chromophore. The cyclic voltammetry in acetonitrile revealed reversible redox processes in 1-3 and 5, except for the Ni(II) complex 4, where a quasi-reversible process was dominantly observed. Presence of the two 2-pyridylmethyl pendant arms in L with a stronger σ-donor/π-acceptor ability had a great impact on the properties of all the complexes (1-5), concretely: (i) strong pyridine-metal bonds provided slight axial compression of the coordination sphere, (ii) substantial changes in magnetic anisotropy, and (iii) stabilization of lower oxidation states. PMID:27245288

  2. A chelate-stabilized ruthenium(sigma-pyrrolato) complex: resolving ambiguities in nuclearity and coordination geometry through 1H PGSE and 31P solid-state NMR studies.

    Science.gov (United States)

    Foucault, Heather M; Bryce, David L; Fogg, Deryn E

    2006-12-11

    Reaction of RuCl2(PPh3)3 with LiNN' (NN' = 2-[(2,6-diisopropylphenyl)imino]pyrrolide) affords a single product, with the empirical formula RuCl[(2,6-iPr2C6H3)N=CHC4H3N](PPh3)2. We identify this species as a sigma-pyrrolato complex, [Ru(NN')(PPh3)2]2(mu-Cl)2 (3b), rather than mononuclear RuCl(NN')(PPh3)2 (3a), on the basis of detailed 1D and 2D NMR characterization in solution and in the solid state. Retention of the chelating, sigma-bound iminopyrrolato unit within 3b, despite the presence of labile (dative) chloride and PPh3 donors, indicates that the chelate effect is sufficient to inhibit sigma --> pi isomerization of 3b to a piano-stool, pi-pyrrolato structure. 2D COSY, SECSY, and J-resolved solid-state 31P NMR experiments confirm that the PPh3 ligands on each metal center are magnetically and crystallographically inequivalent, and 31P CP/MAS NMR experiments reveal the largest 99Ru-31P spin-spin coupling constant (1J(99Ru,31P) = 244 +/- 20 Hz) yet measured. Finally, 31P dipolar-chemical shift spectroscopy is applied to determine benchmark phosphorus chemical shift tensors for phosphine ligands in hexacoordinate ruthenium complexes.

  3. A Mononuclear Co(II) Coordination Complex Locked in a Confined Space and Acting as an Electrochemical Water-Oxidation Catalyst: A "Ship-in-a-Bottle" Approach.

    Science.gov (United States)

    Manna, Paulami; Debgupta, Joyashish; Bose, Suranjana; Das, Samar K

    2016-02-12

    Preparing efficient and robust water oxidation catalyst (WOC) with inexpensive materials remains a crucial challenge in artificial photosynthesis and for renewable energy. Existing heterogeneous WOCs are mostly metal oxides/hydroxides immobilized on solid supports. Herein we report a newly synthesized and structurally characterized metal-organic hybrid compound [{Co3 (μ3 -OH)(BTB)2(dpe)2} {Co(H2O)4(DMF)2}0.5]n ⋅n H2O(Co-WOC-1) as an effective and stable water-oxidation electrocatalyst in an alkaline medium. In the crystal structure of Co-WOC-1, a mononuclear Co(II) complex {Co(H2O)4(DMF)2}(2+) is encapsulated in the void space of a 3D framework structure and this translationally rigid complex cation is responsible for a remarkable electrocatalytic WO activity, with a catalytic turnover frequency (TOF) of 0.05 s(-1) at an overpotential of 390 mV (vs. NHE) in 0.1 m KOH along with prolonged stability. This host-guest system can be described as a "ship-in-a-bottle", and is a new class of heterogeneous WOC. PMID:26757444

  4. The Slx4-Dpb11 scaffold complex: coordinating the response to replication fork stalling in S-phase and the subsequent mitosis.

    Science.gov (United States)

    Princz, Lissa N; Gritenaite, Dalia; Pfander, Boris

    2015-01-01

    Replication fork stalling at DNA lesions is a common problem during the process of DNA replication. One way to allow the bypass of these lesions is via specific recombination-based mechanisms that involve switching of the replication template to the sister chromatid. Inherent to these mechanisms is the formation of DNA joint molecules (JMs) between sister chromatids. Such JMs need to be disentangled before chromatid separation in mitosis and the activity of JM resolution enzymes, which is under stringent cell cycle control, is therefore up-regulated in mitosis. An additional layer of control is facilitated by scaffold proteins. In budding yeast, specifically during mitosis, Slx4 and Dpb11 form a cell cycle kinase-dependent complex with the Mus81-Mms4 structure-selective endonuclease, which allows efficient JM resolution by Mus81. Furthermore, Slx4 and Dpb11 interact even prior to joining Mus81 and respond to replication fork stalling in S-phase. This S-phase complex is involved in the regulation of the DNA damage checkpoint as well as in early steps of template switch recombination. Similar interactions and regulatory principles are found in human cells suggesting that Slx4 and Dpb11 may have an evolutionary conserved role organizing the cellular response to replication fork stalling.

  5. Bipolar mass spectrometry of labile coordination complexes, redox active inorganic compounds, and proteins using a glass nebulizer for sonic-spray ionization.

    Science.gov (United States)

    Antonakis, Manolis M; Tsirigotaki, Alexandra; Kanaki, Katerina; Milios, Constantinos J; Pergantis, Spiros A

    2013-08-01

    In this study, we report on the development of a novel nebulizer configuration for sonic-spray ionization (SSI) mass spectrometry (MS), more specifically for a version of SSI that is referred to as Venturi easy ambient sonic-spray ionization (V-EASI) MS. The developed nebulizer configuration is based on a commercially available pneumatic glass nebulizer that has been used extensively for aerosol formation in atomic spectrometry. In the present study, the nebulizer was modified in order to achieve efficient V-EASI-MS operation. Upon evaluating this system, it has been demonstrated that V-EASI-MS offers some distinct advantages for the analysis of coordination compounds and redox active inorganic compounds over the predominantly used electrospray ionization (ESI) technique. Such advantages, for this type of compounds, are demonstrated here for the first time. More specifically, a series of labile heptanuclear heterometallic [Cu(II) 6Ln(III)] clusters held together with artificial amino acid ligands, in addition to easily oxidized inorganic oxyanions of selenium and arsenic, were analyzed. The observed advantages pertain to V-EASI appearing to be a "milder" ionization source than ESI, not requiring electrical potentials for gas phase ion formation, thus eliminating the possibility of unwanted redox transformations, allowing for the "simultaneous" detection of negative and positive ions (bipolar analysis) without the need to change source ionization conditions, and also not requiring the use of syringes and delivery pumps. Because of such features, especially because of the absence of ionization potentials, EASI can be operated with minimal requirements for source parameter optimization. We observed that source temperature and accelerating voltage do not seem to affect labile compounds to the extent they do in ESI-MS. In addition, bipolar analysis of proteins was demonstrated here by acquiring both positive and negative ion mass spectra from the same protein solutions

  6. Useful Method for the Preparation of Low-Coordinate Nickel(I) Complexes via Transformations of the Ni(I) Bis(amido) Complex K{Ni[N(SiMe3)(2,6- (i) Pr2-C6H3)]2}

    Science.gov (United States)

    Lipschutz, Michael I; Tilley, T Don

    2014-10-13

    A convenient method of preparing two- and three-coordinate Ni(I) complexes of the form L-Ni(I)-X (L = P (t) Bu3, P (i) Pr3, DPPE, NHC; X = -N(SiMe3)(2,6- (i) Pr-C6H3), -O(2,6- (t) Bu2-4-Me-C6H2)) is reported. Protonation of the easily prepared anionic Ni(I) bis(amido) complex K{Ni[N(SiMe3)(2,6- (i) Pr-C6H3)]2} in the presence of an appropriate L-type ligand results in loss of HN(SiMe3)(2,6- (i) Pr-C6H3) and trapping of the resulting neutral Ni(I)-amido fragment to yield neutral, paramagnetic, two- and three-coordinate Ni(I) complexes. Protonation of these neutral amido complexes by the bulky phenol HO(2,6- (t) Bu2-4-Me-C6H2) results in loss of the second amido moiety and trapping by the resulting phenoxide to yield Ni(I)-O(2,6- (t) Bu2-4-Me-C6H2) complexes. The hapticity of the phenoxide ligand is influenced by the π-accepting ability of the L-type ligand. Where L = P (t) Bu3, a poor π-acceptor, the phenoxide acts as a π-acceptor and adopts a η(5)-bonding mode through dearomatization of the phenyl ring. When L = NHC, a competent π-acceptor, the phenoxide acts as a π-donor, adopting a η(1)-bonding mode through the O atom. The modular nature of this synthetic strategy allows variation of both the L- and X-type ligands of the complex in a stepwise fashion and should be extendable to a wide variety of ligand types for new Ni(I) complexes.

  7. Correlation between slow magnetic relaxation and the coordination structures of a family of linear trinuclear Zn(II)-Ln(III)-Zn(II) complexes (Ln = Tb, Dy, Ho, Er, Tm and Yb).

    Science.gov (United States)

    Maeda, Moe; Hino, Shiori; Yamashita, Kei; Kataoka, Yumiko; Nakano, Motohiro; Yamamura, Tomoo; Kajiwara, Takashi

    2012-11-28

    Six linear trinuclear [Ln{Zn(L)(AcO)}(2)]BPh(4) complexes (H(2)L denotes the Schiff-base ligand formed by a condensation reaction between ethylenediamine and two equivalents of o-vanillin), including Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5) and Yb (6) were synthesized and were confirmed to be isostructural via X-ray crystallographic analyses. The Ln(III) ion in each complex is deca-coordinated by four equatorial oxygen donors from the methoxo groups of the Schiff-base ligands, two oxygen donors from the acetate anions and four axial oxygen donors from the phenoxo groups of the Schiff-base ligands. AC susceptibility measurements, with an oscillating frequency of 10 to 10,000 Hz, revealed that 1, 2, 4 and 6 show slow magnetic relaxation under a 1000 Oe DC bias field, which occurs via a single process, as confirmed by the semi-circular Cole-Cole plots. These complexes are considered to be field-induced single-molecule magnets under these conditions. The presence or absence of the slow magnetic relaxation process is discussed by correlating the characteristic magnetic anisotropy of each Ln(III) ion with the ligand field anisotropy.

  8. Toward models for the full oxygen-evolving complex of photosystem II by ligand coordination to lower the symmetry of the Mn3CaO4 cubane: demonstration that electronic effects facilitate binding of a fifth metal.

    Science.gov (United States)

    Kanady, Jacob S; Lin, Po-Heng; Carsch, Kurtis M; Nielsen, Robert J; Takase, Michael K; Goddard, William A; Agapie, Theodor

    2014-10-15

    Synthetic model compounds have been targeted to benchmark and better understand the electronic structure, geometry, spectroscopy, and reactivity of the oxygen-evolving complex (OEC) of photosystem II, a low-symmetry Mn4CaOn cluster. Herein, low-symmetry Mn(IV)3GdO4 and Mn(IV)3CaO4 cubanes are synthesized in a rational, stepwise fashion through desymmetrization by ligand substitution, causing significant cubane distortions. As a result of increased electron richness and desymmetrization, a specific μ3-oxo moiety of the Mn3CaO4 unit becomes more basic allowing for selective protonation. Coordination of a fifth metal ion, Ag(+), to the same site gives a Mn3CaAgO4 cluster that models the topology of the OEC by displaying both a cubane motif and a "dangler" transition metal. The present synthetic strategy provides a rational roadmap for accessing more accurate models of the biological catalyst.

  9. Long-time solution of the time-dependent Schroedinger equation for an atom in an electromagnetic field using complex coordinate contours

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Liang; Vanroose, Wim; Reps, Brian; Rescigno, Thomas N.; McCurdy, C. William

    2009-09-08

    We demonstrate that exterior complex scaling (ECS) can be used to impose outgoing wave boundary conditions exactly on solutions of the time-dependent Schrodinger equation for atoms in intense electromagnetic pulses using finite grid methods. The procedure is formally exact when applied in the appropriate gauge and is demonstrated in a calculation of high harmonic generation in which multiphoton resonances are seen for long pulse durations. However, we also demonstrate that while the application of ECS in this way is formally exact, numerical error can appear for long time propagations that can only be controlled by extending the finite grid. A mathematical analysis of the origins of that numerical error, illustrated with an analytically solvable model, is also given.

  10. Complex coordinated extracellular metabolism: Acid phosphatases activate diluted human leukocyte proteins to generate energy flow as NADPH from purine nucleotide ribose.

    Science.gov (United States)

    Hibbs, John B; Vavrin, Zdenek; Cox, James E

    2016-08-01

    Complex metabolism is thought to occur exclusively in the crowded intracellular environment. Here we report that diluted enzymes from lysed human leukocytes produce extracellular energy. Our findings involve two pathways: the purine nucleotide catabolic pathway and the pentose phosphate pathway, which function together to generate energy as NADPH. Glucose6P fuel for NADPH production is generated from structural ribose of purine ribonucleoside monophosphates, ADP, and ADP-ribose. NADPH drives glutathione reductase to reduce an oxidized glutathione disulfide-glutathione redox couple. Acid phosphatases initiate ribose5P salvage from purine ribonucleoside monophosphates, and transaldolase controls the direction of carbon chain flow through the nonoxidative branch of the pentose phosphate pathway. These metabolic control points are regulated by pH. Biologically, this energy conserving metabolism could function in perturbed extracellular spaces. PMID:26895212

  11. Complex coordinated extracellular metabolism: Acid phosphatases activate diluted human leukocyte proteins to generate energy flow as NADPH from purine nucleotide ribose.

    Science.gov (United States)

    Hibbs, John B; Vavrin, Zdenek; Cox, James E

    2016-08-01

    Complex metabolism is thought to occur exclusively in the crowded intracellular environment. Here we report that diluted enzymes from lysed human leukocytes produce extracellular energy. Our findings involve two pathways: the purine nucleotide catabolic pathway and the pentose phosphate pathway, which function together to generate energy as NADPH. Glucose6P fuel for NADPH production is generated from structural ribose of purine ribonucleoside monophosphates, ADP, and ADP-ribose. NADPH drives glutathione reductase to reduce an oxidized glutathione disulfide-glutathione redox couple. Acid phosphatases initiate ribose5P salvage from purine ribonucleoside monophosphates, and transaldolase controls the direction of carbon chain flow through the nonoxidative branch of the pentose phosphate pathway. These metabolic control points are regulated by pH. Biologically, this energy conserving metabolism could function in perturbed extracellular spaces.

  12. Complex coordinated extracellular metabolism: Acid phosphatases activate diluted human leukocyte proteins to generate energy flow as NADPH from purine nucleotide ribose

    Directory of Open Access Journals (Sweden)

    John B. Hibbs Jr.

    2016-08-01

    Full Text Available Complex metabolism is thought to occur exclusively in the crowded intracellular environment. Here we report that diluted enzymes from lysed human leukocytes produce extracellular energy. Our findings involve two pathways: the purine nucleotide catabolic pathway and the pentose phosphate pathway, which function together to generate energy as NADPH. Glucose6P fuel for NADPH production is generated from structural ribose of purine ribonucleoside monophosphates, ADP, and ADP-ribose. NADPH drives glutathione reductase to reduce an oxidized glutathione disulfide-glutathione redox couple. Acid phosphatases initiate ribose5P salvage from purine ribonucleoside monophosphates, and transaldolase controls the direction of carbon chain flow through the nonoxidative branch of the pentose phosphate pathway. These metabolic control points are regulated by pH. Biologically, this energy conserving metabolism could function in perturbed extracellular spaces.

  13. Iron(III) complexes of N2O and N3O donor ligands as functional models for catechol dioxygenase enzymes: ether oxygen coordination tunes the regioselectivity and reactivity.

    Science.gov (United States)

    Sundaravel, Karuppasamy; Suresh, Eringathodi; Saminathan, Kolandaivel; Palaniandavar, Mallayan

    2011-08-28

    A series of mononuclear iron(III) complexes of the type [Fe(L)Cl(3)], where L is a systematically modified N(2)O or N(3)O ligand with a methoxyethyl/tetrahydrofuryl ether oxygen donor atom, have been isolated and studied as models for catechol dioxygenases. The X-ray crystal structures of [Fe(L2)Cl(3)] 2, [Fe(L6)Cl(3)] 6, [Fe(L5)(TCC)Cl] 5a, where H(2)TCC = tetrachlorocatechol, [Fe(L6)(TCC)Br] 6a, and the μ-oxo dimer [{Fe(L6)Cl}(2)O](ClO(4))(2) 6b have been successfully determined. In [Fe(L2)Cl(3)] 2 the N(2)O ligand is facially coordinated to iron(III) through the pyridine and secondary amine nitrogen atoms and the tetrahydrofuryl oxygen atom. In [Fe(L6)Cl(3)] 6, [Fe(L5)(TCC)Cl] 5a and [Fe(L6)(TCC)Br] 6a the N(3)O donor ligands L5 and L6 act as a tridentate N3 donor ligand coordinated through two pyridine and one secondary amine nitrogen atoms, whereas the ether oxygen is not coordinated. The spectral and electrochemical properties of the adducts [Fe(L)(DBC)Cl] of 1-8, where H(2)DBC = 3,5-di-tert-butylcatechol, in DMF and their solvated adduct species [Fe(L)(DBC)(Sol)](+), where Sol = DMF/H(2)O, generated in situ in dichloromethane, respectively, have been investigated. The product analysis demonstrates that the adducts [Fe(L)(DBC)Cl] effect cleavage of catechol in the presence of O(2) in DMF to give mainly the intradiol (I) product with a small amount of the extradiol (E) product (E/I, 0.2:1-0.7:1). Interestingly, the solvated species [Fe(L)(DBC)(Sol)](+) derived from 1-4 cleave H(2)DBC to provide mainly the extradiol cleavage products with lower amounts of intradiol products (E/I, 2.3:1-4.3:1) in dichloromethane. In contrast, the solvated species [Fe(L)(DBC)(Sol)](+) derived from 5-8 cleave H(2)DBC to provide both extradiol and intradiol products (E/I, 0.6:1-2.3:1) due to the involvement of the ether oxygen donor of the methoxyethyl/tetrahydrofuryl arm in the coordination to iron(III) upon removal of a chloride ion. PMID:21766098

  14. Managing interteam coordination within and between organizations

    OpenAIRE

    de Vries, Thomas Arend

    2015-01-01

    To accomplish complex tasks and effectively respond to environmental contingencies, teams must coordinate task-related issues with other teams (i.e., interteam coordination). Regrettably, interteam coordination is often complicated by misunderstandings that can arise from differences in teams’ languages, routines, and goals. In this dissertation I examine organizational structures, team composition strategies, and individual team member characteristics that can help to overcome such difficult...

  15. 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. PMID:25233287

  16. 聚吡咯-过渡金属-氧配合物储锂材料的结构与性能研究%Polypyrrole-Transition Metal-Oxygen Coordination Complexes as High Performance Lithium Storage Material

    Institute of Scientific and Technical Information of China (English)

    毛亚; 孔庆宇; 郭炳焜; 王兆翔; 陈立泉

    2013-01-01

    Polypyrrole-transition metal-oxygen(PPy-M-O,where M=Fe and Co)coordination complexes have been chemically and electrochemically synthesized and proved to be a brand-new high-performance lithium-storage material.Extended X-ray absorption fine structure(EXAFS)spectroscopy and density functional theory(DFT)calculations indicate that both PPy-Fe-O and PPy-Co-O complexes share a similar multilayer structure.The strong and stable intralayer M(Fe,Co)-N coordination permits the material to possess high specific capacity.The high reversibility of its interlayer M-O-M interaction during cycling ensures high cycling stability and the conducting PPy matrix endows PPy-M-O with outstanding rate performance.Similar lithium storage performances have been obtained in other complexes containing conducting polymers and transition metals.These findings pave new ways to construct a new type of high-performance organic anode materials for lithium ion batteries,high-efficient and inexpensive electrocatalysts for fuel cells,supercapacitors and various other applications.%目前锂离子电池电极材料主要使用无机材料.近年来有机物电极材料虽有报道,但这些材料大都比容量低、倍率性能差.本文介绍一类新型有机金属配合物聚吡咯-过渡金属-氧储锂材料的合成、结构及电化学性能.结合扩展X-射线吸收精细结构谱分析和密度泛函理论计算,发现这类材料呈现多层结构特征,层内稳定的过渡金属-吡咯N的配位作用及循环过程中层间过渡金属-氧键的可逆断裂和结合使该类材料具有很高的储锂容量和循环稳定性,且聚吡咯导电网络使得该材料具有良好的倍率性能.这类新材料将有望成为锂离子电池的高比容量负极材料.

  17. Coordination Chemistry of 2,2'-Bipyridyl- and 2,2':6',2″-Terpyridyl-Substituted BEDT-TTFs: Formation of a Supramolecular Capsule Motif by the Iron(II) Tris Complex of 2,2'-Bipyridine-4-thiomethyl-BEDT-TTF.

    Science.gov (United States)

    Wang, Qiang; Martin, Lee; Blake, Alexander J; Day, Peter; Akutsu, Hiroki; Wallis, John D

    2016-09-01

    Molecules of tris(2,2'-bipyridine-4-thiomethyl-BEDT-TTF)iron(II) (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) assemble in pairs to form a novel supramolecular capsular structure in the solid state. Three BEDT-TTF residues from one complex lie in the three grooves between coordinated bipyridines of the other complex, and vice versa, to form a capsule with 3-fold rotational symmetry and an internal volume of ca. 160 Å(3). Further aspects of the coordination chemistry of this ligand, its 6-substituted isomer, and the 2,2':6'2″-terpyridyl-4'-thiomethyl-BEDT-TTF analogue are described.

  18. Synthesis,crystal structure and photophysical properties of Pr (Ⅲ)coordination complex%一种含Pr(Ⅲ)配合物的合成、晶体结构及光物理性能研究

    Institute of Scientific and Technical Information of China (English)

    迟玉贤; 王瑞雪; 章莹莹

    2014-01-01

    采用水热方法合成了1种Pr(Ⅲ)配合物,[Pr(2,5-pdc)(Ac)(H2 O)·2H2 O]n (2,5-pdc =2,5-吡啶二羧酸根),通过X射线衍射确定了配合物的晶体结构。结果表明,该配合物为单斜晶系,P2(1)/c空间群。在配合物中,Pr(Ⅲ)离子是9配位的,通过醋酸根和2,5-吡啶二羧酸根将配合物连成3D网状结构。室温下测定了配合物晶体粉末的IR光谱,UV-Vis-NIR光谱以及可见区和近红外区的发射光谱。重点研究配合物的发光性能,该配合物在近红外区表现出Pr (Ⅲ)离子的特征发射带,与Pr (Ⅲ)离子的理论发射带相比发生了红移和劈裂现象,可以从配合物的UV-Vis-NIR吸收光谱中得到佐证。%One Pr(Ⅲ)complex ,[Pr(2 ,5-pdc)(Ac)(H2 O)2 H2 O]n (2 ,5-pdc = 2 ,5-pyridine dicarboxy-late) ,was synthesized by the hydrothermal method and its crystal structure was determined by sin-gle-crystal Xray diffraction .Structure analysis reveals that the complex crystallizes in the monoclinic with space group P2(1)/c .In the complex ,the Pr(Ⅲ)ions were nine-coordinated and were bridged in-to 3D network structure by the acetates and 2 ,5-pyridine dicarboxylates .At room temperature ,the IR spectrum、UV-Vis-NIR absorption spectrum and the emission spectra of the complex in the visible and NIR region were measured .The luminescence properties of the complex were emphatically dis-cussed .The emission bands of the NIR spectrum present red-shift and splitting relative to the theo-retical values ,which were evidenced in the UV-Vis-NIR absorption spectrum .

  19. From Coordination Polymer to Monomeric Complex: Two Cobalt Complexes from a Single Demko-Sharpless's Tetrazole Synthesis Reaction%从配位聚合物到单分子化合物的转化:Demko-Sharpless四唑合成法制备两个新颖的Co(Ⅱ)配合物

    Institute of Scientific and Technical Information of China (English)

    瞿志荣

    2007-01-01

    The reaction of CoCl2· 6H2O with 4-cyanopyridine N-oxide in the present of NaN3 affords two novel complexes, {[(POTZ)(H2O)2N3]Co(H2O)} (1) and Co(POTZ)2(H2O)4 (2) (POTZ=4-tetrazolyl pyridine N-oxide), which are two different phases yielded at different stages of a single Demko-Sharpless' tetrazole synthesis reaction.Surprisingly the 1D chain coordination polymer 1 is almost completely converted into monomeric complex 2 in this reaction, and, in a separate test, 2 also can be converted into 1. CCDC: 641222, 1; 641223, 2.

  20. Dicarbollylamine ligand as a tunable template for sigma,sigma- and pi,sigma-bonding modes: syntheses, structures, and theoretical studies of eta5:eta1-coordinated constrained-geometry group 13 metal complexes.

    Science.gov (United States)

    Lee, Jong-Dae; Kim, Sung-Kwan; Kim, Tae-Jin; Han, Won-Sik; Lee, Young-Joo; Yoo, Dae-Hwan; Cheong, Minserk; Ko, Jaejung; Kang, Sang Ook

    2008-07-30

    A series of group 13 main group complexes with pi,sigma-type bonding interaction of the formula [{(eta (5)-RC 2B 9H 9)(CH 2)(eta (1)-NMe 2)}MMe] (M = Al, R = H 5, Me 6; Ga, R = H 7, Me 8; In, R = H 9, Me 10) was produced by the reaction of group 13 metal alkyls (MMe 3; M = Al, Ga, In) with the dicarbollylamine ligands, nido-8-R-7,8-C 2B 9H 10-7-(CH 2)NHMe 2 (R = H 1, Me 2). The reactions of 1 and 2 with AlMe 3 in toluene initially afforded tetra-coordinated aluminum complexes with sigma,sigma-type bonding interaction, [{(eta (1)-RC 2B 9H 10)(CH 2)(eta (1)-NMe 2)}AlMe 2] (R = H 3, Me 4), which readily underwent further methane elimination to yield the corresponding constrained geometry complexes (CGCs, 5 and 6) of aluminum with pi,sigma-bonding interaction. However, the reactions between 1 and 2 and MMe 3 (M = Ga, In) in toluene produced gallium and indium pi,sigma-CGCs of 7 and 10 directly, not proceeding through sigma,sigma-intermediates. The structures of group 13 metal CGCs were established by X-ray diffraction studies of 5, 6, and 8, which authenticated a characteristic eta (5):eta (1)-coordination mode of the dicarbollylamino ligand to the group 13 metals. A similar pi,sigma-bonding interaction was also established in ethylene-bridged dicarbollylethylamine series. Thus, aluminum pi,sigma-CGCs of dicarbollylethylamine, [{(eta (5)-RC 2B 9H 9)(CH 2) 2(eta (1)-NBz 2)}AlMe] (R = H 17, Me 18), were prepared by the trans-metalation of the [{(eta (5)-RC 2B 9H 9)(CH 2) 2(eta (1)-NBz 2)}Ti(NMe 2) 2] (R = H 15, Me 16) with AlMe 3. However, only sigma,sigma-bonded complexes of the formula [{(eta (1)-RC 2B 9H 9)(CH 2) 2(eta (1)-NBz 2)}AlMe 2] (R = H 13, Me 14) were isolated by the reaction between [ nido-7-8-R-7,8-C 2B 9H 10-(CH 2) 2HNBz 2] (R = H 11, Me 12) and AlMe 3. When methane-elimination reactions between metal alkyls and dicarbollylamines were carried out with either the gallium atom or monobenzyl aminoethyl tethered ligands, [ nido-7-H 2NBz(CH 2) 2-8-R-7,8-C 2B 9H

  1. Synthesis and characterization of trinuclear and dinuclear, mononuclear complexes of Ni(II), Pd(II), V O(II) and Co(II) with spheres of coordination N2S2, S2Cl2 and S4O2

    International Nuclear Information System (INIS)

    The coordination chemistry of the tetradentate ligand, 1,4-bis(2-thiol-4-tert-butylbenzyl)piperazine, H2L was studied. The reaction of the ligand dian ionic with divalent metal ions Ni(II), Pd(II) and V O(II) yields monomeric tetra coordinate complexes,: L Ni, L Pd, LVO. The reaction of L Ni or L Pd with dry CoCl2 in acetone afforded complexes LMCoCl2. The complex L Ni reacts with transition metal perchlorates M(CIO4)2 yielding trinuclear compounds of formula. [L Ni M(H2O)2NiL](M(CIO4)2)2' with M Fe''2+, Co''2+ Ni''2+. The complexes were characterized by spectroscopic methods. (Author)

  2. Processing Coordination Ambiguity

    Science.gov (United States)

    Engelhardt, Paul E.; Ferreira, Fernanda

    2010-01-01

    We examined temporarily ambiguous coordination structures such as "put the butter in the bowl and the pan on the towel." Minimal Attachment predicts that the ambiguous noun phrase "the pan" will be interpreted as a noun-phrase coordination structure because it is syntactically simpler than clausal coordination. Constraint-based theories assume…

  3. 1种Nd(Ⅲ)配合物的合成、结构及近红外发光性能研究%Synthesis,crystal structure and NIR luminescence properties of one Nd (Ⅲ) coordination complex

    Institute of Scientific and Technical Information of China (English)

    迟玉贤; 李越; 刘玉娟

    2013-01-01

    Using o-phthalate and adipic acid as the ligands ,one Nd (Ⅲ ) coordination complex , [Nd2 (C8 H4 O4 )2 (C6 H8 O4 )(H2 O)4 ]n ,has been synthesized by the hydrothermal method .The struc-ture of the complex was determined by single crystal Xray diffraction .The complex crystallizes in the triclinic with P1 space group and possesses infinite 3D structure .At room temperature in the solid state ,the IR ,UV-Vis-NIR ,the excitation and emission spectra of the complex were measured and an-alyzed .The complex exhibits characteristic emissions of Nd(Ⅲ) ion in the NIR region ,which should be attributed to the sensitization of the organic ligands .In addition ,in comparison with the theoretical emission bands of Nd(Ⅲ) ion ,the NIR emission bands of the complex present shift ,which can be evi-denced by absorption bands of its UV-Vis-NIR spectrum .This may be attributed to crystal field and the interaction of 4f energy levels of Nd(Ⅲ) ions after the formation of the complex ,so the intra-lev-els are influenced .%采用水热合成方法,以邻苯二甲酸和己二酸为配体,合成了1种具有3D无限结构的Nd(Ⅲ)配位化合物[Nd2(C8 H4 O4)2(C6 H8 O4)(H2 O)4]n ,并得到了它的单晶体。通过X射线单晶衍射,确定了该配合物的晶体结构,该配合物属于三斜晶系,P1空间群。在室温下,测定了配合物晶体粉末的IR光谱,UV-Vis-NIR吸收光谱及荧光激发和发射光谱,并进行了分析指认。该配合物在近红外区表现出明显的Nd(Ⅲ)离子特征发射,这应该是得益于配体的敏化作用。另外,配合物的近红外发射与理论发射相比出现了位移现象,可以从它的UV-Vis-NIR吸收光谱得到佐证,这应该是形成配合物后,在晶体场及Nd(Ⅲ)的4 f能级的相互影响下,体系内部能级得到调谐的结果。

  4. Value-driven coordination process design using physical delivery models

    NARCIS (Netherlands)

    Wieringa, R.J.; Pijpers, V.; Bodenstaff, L.; Gordijn, J.

    2008-01-01

    Current e-business technology enables the execution of increasingly complex coordination processes that link IT services of different companies. Successful design of cross-organizational coordination processes requires the mutual alignment of the coordination process with a commercial business case.

  5. Direct Spectroscopic Observation of Large Quenching of First Order Orbital Angular Momentum with Bending in Monomeric, Two-Coordinate Fe(II) Primary Amido Complexes and the Profound Magnetic Effects of the Absence of Jahn- and Renner-Teller Distortions in Rigorously Linear Coordination

    Science.gov (United States)

    Merrill, W. Alexander; Stich, Troy A.; Brynda, Marcin; Yeagle, Gregory J.; Fettinger, James C.; De Hont, Raymond; Reiff, William M.; Schulz, Charles E.; Britt, R. David; Power, Philip P.

    2009-01-01

    The monomeric iron(II) amido derivatives Fe{N(H)Ar*}2 (1), Ar* = C6H3-2,6-(C6H2-2,4,6-Pri3)2, and Fe{N(H)Ar#}2 (2), Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2, were synthesized and studied in order to determine the effects of geometric changes on their unusual magnetic properties. The compounds, which are the first stable homoleptic primary amides of iron(II), were obtained by the transamination of Fe{N(SiMe3)2}2, with HN(SiMe3)2 elimination, by the primary amines H2NAr* or H2NAr#. X-ray crystallography shows that they have either strictly linear (1) or bent (2, N–Fe–N = 140.9(2)°) iron coordination. Variable temperature magnetization and applied magnetic field Mössbauer spectroscopy studies reveal a very large dependence of the magnetic properties on the metal coordination geometry. At ambient temperature, the linear 1 displayed an effective magnetic moment in the range 7.0 to 7.50 μB, consistent with essentially free ion magnetism. There is a very high internal orbital field component, HL ≈ 170 T which is only exceeded by a HL ≈ 203 T of Fe{C(SiMe3)3}2. In contrast, the strongly bent 2 displays a significantly lower μeff value in the range 5.25 to 5.80 μB at ambient temperature and a much lower orbital field HL value of 116 T. The data for the two amido complexes demonstrate a very large quenching of the orbital magnetic moment upon bending the linear geometry. In addition, a strong correlation of HL with overall formal symmetry is confirmed. ESR spectroscopy supports the existence of large orbital magnetic moments in 1 and 2, and DFT calculations provide good agreement with the physical data. PMID:19670870

  6. Movement coordination during conversation.

    Science.gov (United States)

    Latif, Nida; Barbosa, Adriano V; Vatikiotis-Bateson, Eric; Vatiokiotis-Bateson, Eric; Castelhano, Monica S; Munhall, K G

    2014-01-01

    Behavioral coordination and synchrony contribute to a common biological mechanism that maintains communication, cooperation and bonding within many social species, such as primates and birds. Similarly, human language and social systems may also be attuned to coordination to facilitate communication and the formation of relationships. Gross similarities in movement patterns and convergence in the acoustic properties of speech have already been demonstrated between interacting individuals. In the present studies, we investigated how coordinated movements contribute to observers' perception of affiliation (friends vs. strangers) between two conversing individuals. We used novel computational methods to quantify motor coordination and demonstrated that individuals familiar with each other coordinated their movements more frequently. Observers used coordination to judge affiliation between conversing pairs but only when the perceptual stimuli were restricted to head and face regions. These results suggest that observed movement coordination in humans might contribute to perceptual decisions based on availability of information to perceivers. PMID:25119189

  7. Movement coordination during conversation.

    Directory of Open Access Journals (Sweden)

    Nida Latif

    Full Text Available Behavioral coordination and synchrony contribute to a common biological mechanism that maintains communication, cooperation and bonding within many social species, such as primates and birds. Similarly, human language and social systems may also be attuned to coordination to facilitate communication and the formation of relationships. Gross similarities in movement patterns and convergence in the acoustic properties of speech have already been demonstrated between interacting individuals. In the present studies, we investigated how coordinated movements contribute to observers' perception of affiliation (friends vs. strangers between two conversing individuals. We used novel computational methods to quantify motor coordination and demonstrated that individuals familiar with each other coordinated their movements more frequently. Observers used coordination to judge affiliation between conversing pairs but only when the perceptual stimuli were restricted to head and face regions. These results suggest that observed movement coordination in humans might contribute to perceptual decisions based on availability of information to perceivers.

  8. Adventures in Coordinate Space

    Science.gov (United States)

    Chambers, J. E.

    2003-08-01

    A variety of coordinate systems have been used to study the N-body problem for cases involving a dominant central mass. These include the traditional Keplerian orbital elements and the canonical Delaunay variables, which both incorporate conserved quantities of the two-body problem. Recently, Cartesian coordinate systems have returned to favour with the rise of mixed-variable symplectic integrators, since these coordinates prove to be more efficient than using orbital elements. Three sets of canonical Cartesian coordinates are well known, each with its own advantages and disadvantages. Inertial coordinates (which include barycentric coordinates as a special case) are the simplest and easiest to implement. However, they suffer from the disadvantage that the motion of the central body must be calculated explicitly, leading to relatively large errors in general. Jacobi coordinates overcome this problem by replacing the coordinates and momenta of the central body with those of the system as a whole, so that momentum is conserved exactly. This leads to substantial improvements in accuracy, but has the disadvantage that every object is treated differently, and interactions between each pair of bodies are now expressed in a complicated manner involving the coordinates of many bodies. Canonical heliocentric coordinates (also known as democratic heliocentric coordinates) treat all bodies equally, and conserve the centre of mass motion, but at the cost of introducing momentum cross terms into the kinetic energy. This complicates the development of higher order symplectic integrators and symplectic correctors, as well as the development of methods used to resolve close encounters with the central body. Here I will re-examine the set of possible canonical Cartesian coordinate systems to determine if it is possible to (a) conserve the centre of mass motion, (b) treat all bodies equally, and (c) eliminate the momentum cross terms. I will demonstrate that this is indeed possible

  9. Yeast Interacting Proteins Database: YGL237C, YOR358W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available binding complex, a transcriptional activator and global regulator of respiratory gene expression; contains sequences sufficient...icient for both complex assembly and DNA binding Rows wi...4p/5p CCAAT-binding complex, a transcriptional activator and global regulator of respiratory gene expression; contains sequences suff

  10. Yeast Interacting Proteins Database: YGL237C, YOR047C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available binding complex, a transcriptional activator and global regulator of respiratory gene expression; contains sequences sufficient...p CCAAT-binding complex, a transcriptional activator and global regulator of respiratory gene expression; contains sequences sufficie...nt for both complex assembly and DNA binding Rows with t

  11. Coordinating Interactions: The Event Coordination Notation

    DEFF Research Database (Denmark)

    Kindler, Ekkart

    on a much more technical level. The Event Coordination Notation (ECNO) allows modelling the behaviour of an application on a high level of abstraction that is closer to the application’s domain than to the software realizing it. Still, these models contain all necessary details for actually executing....... The global behaviour of the application results from different elements jointly engaging in such events, which is called an interaction. Which events are supposed to be jointly executed and which elements need to join in is defined by so-called coordination diagrams of the ECNO. Together, the models...

  12. Enhanced time overcurrent coordination

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez, Arturo Conde; Martinez, Ernesto Vazquez [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, Apdo. Postal 114-F, Ciudad Universitaria, CP 66450 San Nicolas de los Garza, Nuevo Leon (Mexico)

    2006-04-15

    In this paper, we recommend a new coordination system for time overcurrent relays. The purpose of the coordination process is to find a time element function that allows it to operate using a constant back-up time delay, for any fault current. In this article, we describe the implementation and coordination results of time overcurrent relays, fuses and reclosers. Experiments were carried out in a laboratory test situation using signals of a power electrical system physics simulator. (author)

  13. Product Architecture as a Coordination System (Japanese)

    OpenAIRE

    OKUNO (FUJIWARA) Masahiro; Watanabe, Yasunori

    2006-01-01

    Baldwin and Clark (2000) brought the substantial attention to the concept of product architecture. This concept, particularly the concept of module architecture, defines a product system as a "coordination system," taking the viewpoint that a product system is an object that is used by human users or developed by human developers. In this paper, product architecture is defined as a design concept for a product system that calls for complex part-to-part coordination in order to fulfill the use...

  14. Resolution enhancement in tilted coordinates

    Science.gov (United States)

    Hariri Naghadeh, Diako; Keith Morley, Christopher

    2016-11-01

    Deconvolution is applied to remove source wavelet effects from seismograms. The results are resolution enhancement that enables detection of thin layers. Following enhancement of resolution, low frequency and high angle reflectors, particularly at great depth, appear as low amplitude and semi-invisible reflectors that are difficult to track and pick. A new approach to enhance resolution is introduced that estimates a derivative using continuous wavelet transform in tilted coordinates. The results are compared with sparse spike deconvolution, curvelet deconvolution and inverse quality filtering in wavelet domain. The positive consequence of the new method is to increase sampling of high dip features by changing the coordinate system from Cartesian to tilted. To compare those methods a complex data set was chosen that includes high angle faults and chaotic mass transport complex. Image enhancement using curvelet deconvolution shows a chaotic system as a non-chaotic one. The results show that sparse spike deconvolution and inverse quality filtering in wavelet domain are able to enhance resolution more than curvelet deconvolution especially at great depth but it is impossible to follow steep dip reflectors after resolution enhancement using these methods, especially when their apparent dips are more than 45°. By estimating derivatives in a continuous wavelet transform from tilted data sets similar resolution enhancement as the other deconvolution methods is achieved but additionally steep dipping reflectors are imaged much better than others. Subtracted results of the enhanced resolution data set using new method and the other introduced methods show that steeply dipping reflectors are highlighted as a particular ability of the new method. The results show that high frequency recovery in Cartesian co-ordinate is accompanied by inability to image steeply dipping reflectors especially at great depths. Conversely recovery of high frequency data and imaging of the data

  15. Coordination failure caused by sunspots

    DEFF Research Database (Denmark)

    Beugnot, Julie; Gürgüç, Zeynep; Øvlisen, Frederik Roose;

    2012-01-01

    In a coordination game with Pareto-ranked equilibria, we study whether a sunspot can lead to either coordination on an inferior equilibrium (mis-coordination) or to out-of equilibrium behavior (dis-coordination). While much of the literature searches for mechanisms to attain coordination on the e......In a coordination game with Pareto-ranked equilibria, we study whether a sunspot can lead to either coordination on an inferior equilibrium (mis-coordination) or to out-of equilibrium behavior (dis-coordination). While much of the literature searches for mechanisms to attain coordination...

  16. Social Postural Coordination

    Science.gov (United States)

    Varlet, Manuel; Marin, Ludovic; Lagarde, Julien; Bardy, Benoit G.

    2011-01-01

    The goal of the current study was to investigate whether a visual coupling between two people can produce spontaneous interpersonal postural coordination and change their intrapersonal postural coordination involved in the control of stance. We examined the front-to-back head displacements of participants and the angular motion of their hip and…

  17. Coordinate measuring machines

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo

    This document is used in connection with three exercises of 2 hours duration as a part of the course GEOMETRICAL METROLOGY AND MACHINE TESTING. The exercises concern three aspects of coordinate measuring: 1) Measuring and verification of tolerances on coordinate measuring machines, 2) Traceability...

  18. Optical activity and Alfred Werner's coordination chemistry.

    Science.gov (United States)

    Ernst, Karl-Heinz; Berke, Heinz

    2011-03-01

    It is widely accepted, that Pasteur's seminal discovery of the opposite optical activity of ammonium sodium tartrate enantiomorphs in solution gave the spark to organic stereochemistry and led to the development of the tetrahedron model by van't Hoff and Le Bel. The proof that chirality is inherently connected to octahedral coordination chemistry fostered greatly Werner's spatial views of metal complexes and his coordination theory. The actual proof of principle was established via separation of diastereomeric camphor sulfonate salts of racemic metal complexes. PMID:20928897

  19. Developments in the Coordination Chemistry of Europium(II)

    OpenAIRE

    Garcia, Joel; Allen, Matthew J.

    2012-01-01

    Recent advances in the coordination chemistry of Eu2+ are reviewed. Common synthetic routes for generating discrete Eu2+-containing complexes reported since 2000 are summarized, followed by a description of the reactivity of these complexes and their applications in reduction chemistry, polymerization, luminescence, and as contrast agents for magnetic resonance imaging. Rapid development of the coordination chemistry of Eu2+ has led to an upsurge in the utilization of Eu2+-containing complexe...

  20. Supercritical Airfoil Coordinates

    Data.gov (United States)

    National Aeronautics and Space Administration — Rectangular Supercritical Wing (Ricketts) - design and measured locations are provided in an Excel file RSW_airfoil_coordinates_ricketts.xls . One sheet is with Non...

  1. Dimensions of Organizational Coordination

    DEFF Research Database (Denmark)

    Jensen, Andreas Schmidt; Aldewereld, Huib; Dignum, Virginia

    2013-01-01

    be supported to include organizational objectives and constraints into their reasoning processes by considering two alternatives: agent reasoning and middleware regulation. We show how agents can use an organizational specification to achieve organizational objectives by delegating and coordinating...

  2. Understanding social motor coordination.

    Science.gov (United States)

    Schmidt, R C; Fitzpatrick, Paula; Caron, Robert; Mergeche, Joanna

    2011-10-01

    Recently there has been much interest in social coordination of motor movements, or as it is referred to by some researchers, joint action. This paper reviews the cognitive perspective's common coding/mirror neuron theory of joint action, describes some of its limitations and then presents the behavioral dynamics perspective as an alternative way of understanding social motor coordination. In particular, behavioral dynamics' ability to explain the temporal coordination of interacting individuals is detailed. Two experiments are then described that demonstrate how dynamical processes of synchronization are apparent in the coordination underlying everyday joint actions such as martial art exercises, hand-clapping games, and conversations. The import of this evidence is that emergent dynamic patterns such as synchronization are the behavioral order that any neural substrate supporting joint action (e.g., mirror systems) would have to sustain.

  3. The curvature coordinate system

    DEFF Research Database (Denmark)

    Almegaard, Henrik

    2007-01-01

    The paper describes a concept for a curvature coordinate system on regular curved surfaces from which faceted surfaces with plane quadrangular facets can be designed. The lines of curvature are used as parametric lines for the curvature coordinate system on the surface. A new conjugate set of lines......, called middle curvature lines, is introduced. These lines define the curvature coordinate system. Using the curvature coordinate system, the surface can be conformally mapped on the plane. In this mapping, elliptic sections are mapped as circles, and hyperbolic sections are mapped as equilateral...... hyperbolas. This means that when a plane orthogonal system of curves for which the vertices in a mesh always lie on a circle is mapped on a surface with positive Gaussian curvature using inverse mapping, and the mapped vertices are connected by straight lines, this network will form a faceted surface...

  4. Attribute coordination in organizations

    OpenAIRE

    Yingyi Qian; Gerard Roland; Chenggang Xu

    2001-01-01

    We study coordination in organizations with a variety of organizational forms. Coordination in organization is modeled as the adjustment of attributes and capacities of tasks when facing external shocks. An M-form (U-form) organization groups complementary (substitutable) tasks together in one unit. In the presence of only attribute shocks, particularly when gains from specialization are small, communication is poor, or shocks are more likely, the expected payoff of the decentralized M-form i...

  5. Training a system-literate care coordination workforce.

    Science.gov (United States)

    Naccarella, Lucio; Osborne, Richard H; Brooks, Peter M

    2016-04-01

    People with chronic complex conditions continue to experience increasing health system fragmentation and poor coordination. To reverse these trends, one solution has been an investment in effective models of care coordination that use a care coordinator workforce. Care coordinators are not a homogenous workforce - but an applied professional role, providing direct and indirect care, and is often undertaken by nurses, allied health professionals, social workers or general practitioners. In Australia, there is no training curriculum nor courses, nor nationally recognised professional quality standards for the care coordinator workforce. With the growing complexity and fragmentation of the health care system, health system literacy - shared understanding of the roles and contributions of the different workforce professions, organisations and systems, among patients and indeed the health workforce is required. Efforts to improve health system literacy among the health workforce are increasing at a policy, practice and research level. However, insufficient evidence exists about what are the health system literacy needs of care coordinators, and what is required for them to be most effective. Key areas to build a health system literate care coordination workforce are presented. Care coordination is more than an optional extra, but one of the only ways we are going to be able to provide equitable health services for people with chronic complex conditions. People with low health literacy require more support with the coordination of their care, therefore we need to build a high performing care coordinator workforce that upholds professional quality standards, and is health literacy responsive.

  6. Continuous parallel coordinates.

    Science.gov (United States)

    Heinrich, Julian; Weiskopf, Daniel

    2009-01-01

    Typical scientific data is represented on a grid with appropriate interpolation or approximation schemes,defined on a continuous domain. The visualization of such data in parallel coordinates may reveal patterns latently contained in the data and thus can improve the understanding of multidimensional relations. In this paper, we adopt the concept of continuous scatterplots for the visualization of spatially continuous input data to derive a density model for parallel coordinates. Based on the point-line duality between scatterplots and parallel coordinates, we propose a mathematical model that maps density from a continuous scatterplot to parallel coordinates and present different algorithms for both numerical and analytical computation of the resulting density field. In addition, we show how the 2-D model can be used to successively construct continuous parallel coordinates with an arbitrary number of dimensions. Since continuous parallel coordinates interpolate data values within grid cells, a scalable and dense visualization is achieved, which will be demonstrated for typical multi-variate scientific data.

  7. Continuous parallel coordinates.

    Science.gov (United States)

    Heinrich, Julian; Weiskopf, Daniel

    2009-01-01

    Typical scientific data is represented on a grid with appropriate interpolation or approximation schemes,defined on a continuous domain. The visualization of such data in parallel coordinates may reveal patterns latently contained in the data and thus can improve the understanding of multidimensional relations. In this paper, we adopt the concept of continuous scatterplots for the visualization of spatially continuous input data to derive a density model for parallel coordinates. Based on the point-line duality between scatterplots and parallel coordinates, we propose a mathematical model that maps density from a continuous scatterplot to parallel coordinates and present different algorithms for both numerical and analytical computation of the resulting density field. In addition, we show how the 2-D model can be used to successively construct continuous parallel coordinates with an arbitrary number of dimensions. Since continuous parallel coordinates interpolate data values within grid cells, a scalable and dense visualization is achieved, which will be demonstrated for typical multi-variate scientific data. PMID:19834230

  8. Magnetic Coordinate Systems

    Science.gov (United States)

    Laundal, K. M.; Richmond, A. D.

    2016-07-01

    Geospace phenomena such as the aurora, plasma motion, ionospheric currents and associated magnetic field disturbances are highly organized by Earth's main magnetic field. This is due to the fact that the charged particles that comprise space plasma can move almost freely along magnetic field lines, but not across them. For this reason it is sensible to present such phenomena relative to Earth's magnetic field. A large variety of magnetic coordinate systems exist, designed for different purposes and regions, ranging from the magnetopause to the ionosphere. In this paper we review the most common magnetic coordinate systems and describe how they are defined, where they are used, and how to convert between them. The definitions are presented based on the spherical harmonic expansion coefficients of the International Geomagnetic Reference Field (IGRF) and, in some of the coordinate systems, the position of the Sun which we show how to calculate from the time and date. The most detailed coordinate systems take the full IGRF into account and define magnetic latitude and longitude such that they are constant along field lines. These coordinate systems, which are useful at ionospheric altitudes, are non-orthogonal. We show how to handle vectors and vector calculus in such coordinates, and discuss how systematic errors may appear if this is not done correctly.

  9. Construction of a monoanionic S,N,S-pincer ligand with a pyrrole core by sequential [1,2] phospho-Fries rearrangement. Characterization of palladium and silver coordination complexes

    NARCIS (Netherlands)

    Fraix, A.; Lutz, M.; Spek, A.L.; Klein Gebbink, R.J.M.; van Koten, G.; Salaun, J. -Y; Jaffrès, P. -A

    2010-01-01

    The synthesis of an S,NH,S-pincer ligand possessing a pyrrole core and two O,O-diethylthiophosphonyl groups to design PS lateral coordination sites is reported. The synthetic procedure to produce this ligand makes use of the nitrogen atom of the pyrrole heterocycle to successively functionalize the

  10. The coordination chemistry of saturated molecules

    OpenAIRE

    Bercaw, John E.; Labinger, Jay A.

    2007-01-01

    Our understanding of bonding in transition metal complexes, as well as our ability to use that understanding in the synthesis and application of new species, has evolved over the last 100 years; and in some sense this special feature on the coordination chemistry of saturated molecules may be considered to represent its culmination. The nature of complexes between transition metal ions and neutral molecules such as ammonia was first correctly described by Werner around the beginning of the 20...

  11. The brave new world of coordination frameworks.

    Science.gov (United States)

    Champness, Neil R

    2013-01-14

    In 1994 the field of coordination frameworks was still in its infancy and yet to give birth to its offspring research field of metal-organic frameworks (MOFs). Studies by Zaworotko and Ciani served to illustrate both the simplicity and the complexity of these remarkable structures.

  12. Complex Covariance

    Directory of Open Access Journals (Sweden)

    Frieder Kleefeld

    2013-01-01

    Full Text Available According to some generalized correspondence principle the classical limit of a non-Hermitian quantum theory describing quantum degrees of freedom is expected to be the well known classical mechanics of classical degrees of freedom in the complex phase space, i.e., some phase space spanned by complex-valued space and momentum coordinates. As special relativity was developed by Einstein merely for real-valued space-time and four-momentum, we will try to understand how special relativity and covariance can be extended to complex-valued space-time and four-momentum. Our considerations will lead us not only to some unconventional derivation of Lorentz transformations for complex-valued velocities, but also to the non-Hermitian Klein-Gordon and Dirac equations, which are to lay the foundations of a non-Hermitian quantum theory.

  13. Postural Coordination during Socio-motor Improvisation.

    Science.gov (United States)

    Gueugnon, Mathieu; Salesse, Robin N; Coste, Alexandre; Zhao, Zhong; Bardy, Benoît G; Marin, Ludovic

    2016-01-01

    Human interaction often relies on socio-motor improvisation. Creating unprepared movements during social interaction is not a random process but relies on rules of synchronization. These situations do not only involve people to be coordinated, but also require the adjustment of their posture in order to maintain balance and support movements. The present study investigated posture in such a context. More precisely, we first evaluated the impact of amplitude and complexity of arm movements on posture in solo situation. Then, we assessed the impact of interpersonal coordination on posture using the mirror game in which dyads performed improvised and synchronized movements (i.e., duo situation). Posture was measured through ankle-hip coordination in medio-lateral and antero-posterior directions (ML and AP respectively). Our results revealed the spontaneous emergence of in-phase pattern in ML direction and antiphase pattern in AP direction for solo and duo situations. These two patterns respectively refer to the simultaneous flexion/extension of the ankles and the hips in the same or opposite direction. It suggests different functional roles of postural coordination patterns in each direction, with in-phase supporting task performance in ML (dynamical stability) and antiphase supporting postural control in AP (mechanical stability). Although amplitude of movement did not influence posture, movement complexity disturbed postural stability in both directions. Conversely, interpersonal coordination promoted postural stability in ML but not in AP direction. These results are discussed in terms of the difference in coupling strength between ankle-hip coordination and interpersonal coordination.

  14. Several Novel N-Donor Tridentate Ligands Formed in Chemical Studies of New fac-Re(CO)3 Complexes Relevant to fac-99mTc(CO)3 Radiopharmaceuticals. Attack of a Terminal Amine on Coordinated Acetonitrile

    OpenAIRE

    Perera, Theshini; Marzilli, Patricia A.; Fronczek, Frank R.; Marzilli, Luigi G.

    2010-01-01

    A novel ligand was discovered in which acetonitrile appears to have inserted between the two protons and the nitrogen of a primary amine. A proposed pathway for this process involves a putative seven-membered chelate ring (formed by attack of a primary amine on coordinated acetonitrile) that undergoes proton transfer and rearrangement. The pathway is supported by the structure of a related compound that has a methyl group in place of one of the protons.

  15. Quantifying linguistic coordination

    DEFF Research Database (Denmark)

    Fusaroli, Riccardo; Tylén, Kristian

    ). We employ nominal recurrence analysis (Orsucci et al 2005, Dale et al 2011) on the decision-making conversations between the participants. We report strong correlations between various indexes of recurrence and collective performance. We argue this method allows us to quantify the qualities......Language has been defined as a social coordination device (Clark 1996) enabling innovative modalities of joint action. However, the exact coordinative dynamics over time and their effects are still insufficiently investigated and quantified. Relying on the data produced in a collective decision...

  16. Coordinate Standard Measurement Development

    Energy Technology Data Exchange (ETDEWEB)

    Hanshaw, R.A.

    2000-02-18

    A Shelton Precision Interferometer Base, which is used for calibration of coordinate standards, was improved through hardware replacement, software geometry error correction, and reduction of vibration effects. Substantial increases in resolution and reliability, as well as reduction in sampling time, were achieved through hardware replacement; vibration effects were reduced substantially through modification of the machine component dampening and software routines; and the majority of the machine's geometry error was corrected through software geometry error correction. Because of these modifications, the uncertainty of coordinate standards calibrated on this device has been reduced dramatically.

  17. A channel-based coordination model for component composition

    NARCIS (Netherlands)

    Arbab, F.

    2002-01-01

    In this paper, we present $P epsilon omega$, a paradigm for composition of software components based on the notion of mobile channels. $P repsilon omega$ is a channel-based exogenous coordination model wherein complex coordinators, called {em connectors are compositionally built out of simpler ones.

  18. Reo: A Channel-based Coordination Model for Component Composition

    NARCIS (Netherlands)

    Arbab, F.

    2004-01-01

    In this paper, we present Reo, which forms a paradigm for composition of software components based on the notion of mobile channels. Reo is a channel-based exogenous coordination model in which complex coordinators, called connectors, are compositionally built out of simpler ones. The simplest conne

  19. A Framework for ICT-Supported Coordination in Crisis Response

    NARCIS (Netherlands)

    Gonzalez, R.A.

    2010-01-01

    Crisis response efforts often require coordinating a previously unknown adhocracy of agencies under time pressure. While current technologies that support coordination are successful for well-defined static process descriptions, they may fall short in the face of more complex and unpredictable scena

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

    Science.gov (United States)

    El-Boraey, Hanaa A.

    2012-11-01

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