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Dissertations / Theses on the topic 'Ligand systems'

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Published: 4 June 2021
Last updated: 11 February 2022

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1

Freundlich, Joel Stephen. "Metal-ligand multiple bonds in organometallic complexes containing triamidoamine ligand systems." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38782.

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2

Taylor, Steven John. "Exploratory studies of novel ligand systems." Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1004973.

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A range of novel ligand systems have been developed in three distinct phases and preliminary studies have been initiated to evaluate their complexation potential. Phase I incorporated the synthesis of single strand ligand systems, which were mainly based on amino acid residues. Techniques have been developed for the attachment of these ligand systems onto, firstly, a styrene monomer, and then later onto a pseudo-styrene linking group, viz. the p-toluoyl group. The linking reactions were based on the formation of amides or esters by the reaction of an acid chloride system with an amine or alcohol. Phase II involved the synthesis of bis-chain ligand systems and their attachment onto the p-toluoyl linking group. A further linking group was also developed at this stage, viz. the xylyl group. In the preparation of phase II ligand systems, use was made of malonic ester and iminodiacetic acid derivatives. Phase III has involved the synthesis of cyclic ligand systems, with skeletons based upon the structures used in phase I and phase II and two crown ether type systems have been prepared.
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3

Kidd, Sara Jean. "Studies of group 15/nitrogen ligand systems." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621394.

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4

Paul, Diana Rachel. "The development of new organolead reagents in organic synthesis." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320635.

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5

Bujotzek, Alexander [Verfasser]. "Molecular Simulation of Multivalent Ligand-Receptor Systems / Alexander Bujotzek." Berlin : Freie Universität Berlin, 2013. http://d-nb.info/1041255721/34.

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6

Peace, Richard John. "Bulky ligand systems containing pi-acidic aryl and carboranyl groups." Thesis, Durham University, 1996. http://etheses.dur.ac.uk/5388/.

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This thesis describes studies into the synthesis and coordination chemistry of ligands containing bulky π-acidic groups. Both π-acidic aryl and carboranyl groups have been investigated. Chapter One highlights electronic and structural aspects of ligands investigated and computational techniques employed. Chapter Two describes the synthesis of aromatic systems bearing nitrogen substituents and trifluoromethyl groups, with a view to their use in the synthesis of new ligands. The π -interaction between the nitrogen substituent and aromatic ring has been investigated and is found to vary considerably with the nature of the substituent and position of the CF(_3) groups on the ring. Chapter Three describes the synthesis of molybdenum compounds containing CF3 substituted aryl-imido ligands. The presence of the π-acidic group is found to decrease π-bonding from the ligand to the metal which results in changes in the reactivity of such complexes. Chapter Four describes the synthesis of nitrogen-substituted carboranes 1- NHX-2-R-l,2-C(_2)B (_10)H(_10) (R = Me, Ph; X = 2-R-l,2-C(_2)B(_10)H(_10), NHAr, OH, H) and 1- NX-2-R-C(_2)B(_10)H(_10) (R = Me, Ph; X = 0, NAr). The structures of many of these compounds are described and the π-interaction between the cage and substituent investigated. This 7t-interaction determines the orientation of the substituent relative to the cage and causes changes in the geometry of the cage. The "B NMR shift of the atom directly opposite the nitrogen substituent is found to give an accurate indication of the exo π-bond order. In light of these observations data from other systems have been re-examined. Chapter Five describes the incorporation of carborane containing ligands into metal systems. The π-acidic carboranyl group reduces 7i-bonding from the ligand to the metal. The consequences of this on the structure and reactivity of these complexes are discussed. Chapter Six gives experimental details for Chapters Two to Five. Richard John Peace (August 1996).
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7

Li, Aixiao. "Molecular modeling of non-bonding interactions in biomolecules-ligand systems." Paris 7, 2009. http://www.theses.fr/2009PA077032.

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Ce travail est consacré à la modélisation des interactions entre des inhibiteurs et des molécules impliquées dans la cancérisation, dans le but notamment d'établir de manière précise les modes d'interaction biomolécules-ligand. Dans la famille des CDK (cyclin dépendant kinases) nous nous sommes intéressés à la sélectivité que présente un nouvel inhibiteur (2PU) vis-à-vis de CDK4 par rapport à CDK2. Les méthodes employées : dynamique moléculaire, calculs d'énergies d'interaction, docking et méthodes mixtes du type ONIOM ont permis d'établir les raisons précises de la sélectivité en mettant en évidence des interactions privilégiées (notamment des liaisons H) entre l'inhibiteur et CDK4. Sur le plan méthodologique la méthode ONIOM (à deux ou trois couches) a fait l'objet d'une étude minutieuse et originale quant à la procédure de définition de la partition du système. Une nouvelle approche est proposée. La stabilisation du DNA G-quadruplex par un nouveau ligand (TQMP) a également été étudiée par dynamique moléculaire, ce qui a permis de préciser les modes d'interaction et de démontrer la sélectivité de l'un des deux sites possibles d'interaction
This work is devoted to modelling the interactions between some inhibitors and molecules involved in cancer development and aims at precisely establishing the interactions modes between the ligands and the biomolecules. In the CDK (cyclin dependant kinases) family we have examined the selectivity of a new inhibitor (2PU) towards CDK4 as compared to CDK2. The techniques we have used : molecular dynamics interaction energies calculation, molecular docking and mixed methods of the ONIOM type allowed us to establish the precise causes of this selectivity, showing the existence of specific interactions (H bonds, among others) between the inhibitor and CDK4. From a methodological point of view, the ONIOM method (with 2 or 3 layers) has been carefully examined with respect to the System partitioning procedure. A new approach is proposed. The stabilisation of G-quadruplex DNA by a new ligand (TQMP) has also been studied with molecular dynamics, which allowed establishing the interaction modes and show the selectivity of one of the 2 possible interaction sites
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8

Tran, Anh. "Ruthenium-Manganese Complexes as Model Systems for Artificial Photosynthesis." Doctoral thesis, KTH, Chemistry, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3169.

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9

Larsson, Rikard. "Dynamic Systems for Screening, Control and Identification of Protein-Ligand Interactions." Doctoral thesis, Stockholm : Kemi, Chemistry, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4709.

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10

Bunn, Natalie R. "Synthetic and structural studies of low coordinate group 13 ligand systems." Thesis, Cardiff University, 2005. http://orca.cf.ac.uk/56114/.

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A new generation of diode lasers is being developed using quantum dots as the gain generating medium. A detailed understanding of the carrier recombination mechanisms and optical gain generation is essential for optimisation of their performance. The aim of this work is to further understand the optical processes occurring in quantum dots. In particular, the effect of the localisation of the energy states in the dots on the recombination mechanisms and the gain/absorption is studied. It is often assumed that the rates of nonradiative recombination via defects, radiative recombination and Auger recombination are proportional to linear, quadratic and cubic functions of the carrier number respectively. The derivation of these functional forms is possible in quantum well and bulk structures because the extended electronic states make it meaningful to talk of a global carrier population. In a quantum dot system the dependence of the recombination processes on the total number of electrons populating the dots is modified by the localisation of all the recombination processes. In this thesis a computer model has been developed in which the dots are occupied by integer numbers of electrons and holes, with electron and hole occupancies controlled by Fermi-Dirac statistics. The recombination processes have similar dependences on the electron number and there is no clear transition from one process to another as the injection level is increased. These dependences cannot be represented by simple power law functions of the carrier number. An alternative model, in which each dot is electrically neutral, has also been studied, and the two models show significant differences for the hole distribution as the injection is increased. It is found that analyses based on power law relations between recombination rates and carrier number, as used for extended state systems, cannot be applied to localised recombination in dots.
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11

Deitinghoff, Lutz Alexander. "Identifizierung und Charakterisierung eines neuen Ligand-Rezeptor-Systems der retinotectalen Projektion." [S.l. : s.n.], 2003. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10910385.

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12

Smart, Varrie Russell. "Synthesis of Modular Pseudopeptide Ligand Systems for Modeling Enzyme Active Sites." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1314145817.

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13

Stollberg, Peter. "Synthesis and Characterization of Polydentate C3 Symmetric Ligand Systems in Metal Coordination." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/21.11130/00-1735-0000-0003-C119-7.

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14

Benson, Mark Adam. "N-functionalised cyclotriphosphazenes; towards new polycations , acylation catalysts and zwitterionic ligand systems." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443931.

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15

Tenenbaum, Jessica Dale. "Expression-based ligand signature analysis (ELSA) : a foray into integrative systems medicine /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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16

Pandrapragada, Ravi Kumar. "Synthesis and characterization of novel phosphinimine ligand systems for potential applications in radiopharmaceuticals." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5100.

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Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Nov. 1, 2007). Vita. Includes bibliographical references.
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17

Worbs, Sylvia [Verfasser]. "Charakterisierung der Expression und Modulation des HVEM-BTLA-Ligand-Rezeptor-Systems / Sylvia Worbs." Berlin : Freie Universität Berlin, 2009. http://d-nb.info/1023747391/34.

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18

Rowan, Michael. "a-olefin polymerisation using group V procatalysts bearing calixarenes and related ligand systems." Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432437.

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19

Rodger, Philip J. A. "Development of new mixed metal and ligand systems in s-block amide chemistry." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248980.

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20

Lawlor, Susan Elizabeth. "Synthesis and metal binding properties of novel C←2-symmetric tetraaza ligand systems." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342639.

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21

Irwin, Mark Robert Floyd. "The synthesis and characterisation of metal complexes containing chemically reduced bipyridyl ligand systems." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:44dd8d43-01cf-4a2a-ab66-c7cab1d9201f.

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This thesis describes the synthesis and characterisation of metal complexes that contain chemically reduced bipyridyl ligands. The crystal structures of twenty-six novel complexes are reported alongside detailed discussions on the electronic and spectroscopic effects and trends associated with the different oxidation states within these species. Chapter One introduces the isomers of bipyridine and their redox chemistry, the concept of non-innocent ligands and the spectroscopic techniques that are currently used in determining ligand oxidation states. Subsequently, examples of main group, transition metal, lanthanide and actinide species that contain or may contain reduced forms of the ligand are discussed. Chapter Two details the synthesis and structural characterisation of alkali metal salts of singly and doubly reduced forms of the three commercially available bipyridine isomers. The effects of this reduction are investigated with the aim of developing diagnostic fingerprints for each of the ligand oxidation states. Chapter Three discusses the synthesis of an homologous series of compounds of the form [M(2,2'-bipy)(mes)2]n– where M = Cr, Mn, Fe, Co, Ni and n = 0, 1. Trends in magnetism, bonding and electronic structure are investigated with reference to theoretical calculations and the diagnostic fingerprints identified in the previous chapter. Chapter Four describes the synthesis and characterisation of three compounds containing the isostructural motif [Zn2(4,4'-bipy)(mes)4]n– where n = 0, 1, 2. Structural and spectroscopic changes are discussed and com- pared to theoretical calculations. Chapter Five contains descriptions of the spectroscopic techniques employed in the above research and synthesis routes to all compounds featured in this thesis.
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22

Dube, Tiffany Lynn. "Organometallic transformations of di-and trivalent samarium supported by polydentate macrocyclic ligands, low-valent samarium complexes of di-and tetrapyrrole ligand systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/NQ57037.pdf.

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23

Dubé, Tiffany. "Organometallic transformations of di- and trivalent samarium supported by polydentate macrocyclic ligands: Low-valent samarium complexes of di- and tetrapyrrole ligand systems." Thesis, University of Ottawa (Canada), 2000. http://hdl.handle.net/10393/8652.

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SmI2(THF)5 acted as a reducing agent in the reaction with phenylenebis(3,5-But4salicylidene)iminato sodium, (3,5-But4salophen)Na2(THF) 2, to yield a dimeric compound [Sm2(SB-SB)(THF)3] ·2toluene (2.2) [SB-SB = C-C bonded (3,5-Bu t4salophen dimer] arising from the reductive C-C coupling of two imine functional groups of two (3,5-But4salophen)Sm units. Complex 2.2 reacts with MeLi resulting in a novel oxo-bridged dimer, {[(Me2-SB)Sm(mu-CH3)Li(THF)][(Me2-SB)Sm(mu-CH 3)Li(THF)2Li(TBT)2]}(mu-O)(mu-Li)3 (2.3) [Me2SB = phenylenebis (3,5-But 4salicyl)dimethyldiamidato], featuring alkylation of both Sm atoms and arising from cleavage of the C-C bond connecting the two units, as well as complete reduction of the imine groups of the two salophen ligands and TBF deoxygenation. Similar cleavage of the connecting C-C bond of complex 2.2 was also observed during the reaction with dry O2 to form a distorted cuboid cluster in which four Sm atoms are bridged by four hydroxyl groups [(3,5-But4salophen)Sm (OH)] 4·4toluene (2.4). The nature of the substituents present on the calix-tetrapyrrole tetra-anion ligand {[R2C(C4H2N)]4} 4- [R = 1/2-(CH2)5- (a), Et (b)] determines the type of reactivity of the corresponding Sm(II) compounds with acetylene. Where R = 1/2-(CH2)5- dehydrogenation occurred to yield the nearly colorless dinuclear diacetylide complex. Conversely, where R = Et, acetylene coupling in addition to dehydrogenation resulted in the formation of a dimeric butatrienediyl enolate derivative. Reaction of the trivalent hydride or of the terminally bonded methyl derivative with acetylene resulted in a mixture of the carbide and the dimerization product 5.2b. The same reaction also yielded a third product, a trivalent complex in which the macrocycle was isomerized by shifting the ring attachment of one of the four pyrrole rings. Reaction of the mononuclear and trivalent (6.1a), ( 6.1b) with lithium under Ar in THF afforded the mononuclear divalent 6.3a where the enolate was formed by a THF cleavage process. In the case of direct reaction of SmI2(THF)5 with the tetralithiated form of the Rn-calix-pyrrole ligand, the two isomorphous enolates (6.3a and 6.3b) were the only isolated products. Complexes 6.3 react reversibly with ethylene to afford the corresponding light-green dinuclear ethylene adducts. The nature of the substituents; present on a dipyrrolide dianion ligand determines the assembly of Sm(II) clusters which participate to various extents in dinitrogen fixation and THF cleavage. Reaction of SMI2(THF) 2 with the methylphenyl dipyrromethanyl dianion resulted in the pentameric cluster 10.1 which exhibited no reactivity with dinitrogen. Conversely, reaction of SmI2(THF)2 with the cyclohexyl dipyrromethanyl dianion resulted in TBF cleavage to yield the tetranuclear oxo-bridged complex 10.2. (Abstract shortened by UMI.)
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24

Joy, Jonathan Stuart. "Synthesis and charaterisation of mixed s-/p-block organometallics and p-block ligand systems." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402058.

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25

Dane, Sarah Barbara Joanne. "Applications and activation of novel ligand systems in oxidation catalysis and Ylide-based organometallics." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708166.

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26

Finkenauer, Lauren R. "Ligand-Mediated Stabilization of Low Temperature Metal Eutectics and Their Use in Composite Systems." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/895.

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objective of this thesis is to contribute to the understanding of the behavior of the liquid metal eutectic gallium/indium (EGaIn) in composite systems and provide a platform for the development of functional hybrid nanocomposites. Contributions are regarding (i) the investigation of the electromechanical coupling performance of EGaIn as electrodes in a soft electrostatic transducer and (ii) the effectiveness of organic surfactants to stabilize EGaIn nanoparticles in organic solvents. For the first portion, a completely soft dielectric elastomer actuator (DEA) using EGaIn electrodes was fabricated and evaluated. Experimental actuation of the DEA showed high agreement with a generalized NeoHookean constitutive law, assuming uniaxial pre-stretch and considering the device saddle deformation. The expected conductive behavior of the liquid alloy was confirmed, and further efforts have focused on the development and stabilization of EGaIn nanodroplets, which do not exhibit the problems associated with larger pools of EGaIn (such as leakage) and can be applied to soft multifunctional materials. A computational procedure was developed for calculating suspended EGaIn nanoparticle mass in order to determine reaction yields using applied Mie theory and optical characterization techniques (dynamic light scattering and UV/Vis spectrophotometry). This method calculated total mass to within 20% when applied to a known system. A systematic study evaluating particle yield as a function of aliphatic surfactant composition and concentration (and solvent type) revealed a pronounced dependence of nanodroplet formation on the solvent type as well as surfactant structure. Ethanol (EtOH) was found to be the most effective solvent for the formation and stabilization of EGaIn nanodroplets, in which only thiol-based surfactants were found to improve nanodroplet yield. Results suggest a stabilization mechanism other than the expected self-assembled monolayer (SAM) formation. The research has been extended to alternative (e.g. plant based) surfactant systems.
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27

Stocks, Susan Jill. "Development of a general ligand for immunoaffinity partitioning in two phase aqueous polymer systems." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26085.

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The partition of erythrocytes in a two phase aqueous polymer system composed of dextran T500, poly(ethylene glycol)8000 (PEG 8000) and buffer was studied and the effect of a combination of affinity ligands, namely rabbit IgG and PEG 1900 modified monoclonal IgG, was examined as a potential cell separation technique. Several hybridoma lines secreting mouse monoclonal IgG specific for the F[sub c] receptor of rabbit IgG were produced by the fusion of immunised mice spleen cells and mouse myeloma cells. The monoclonal IgG was modified by cyanuric chloride attachment of PEG 1900. The modified monoclonal antibody partitioned predominantly into the PEG rich upper phase of a two phase aqueous polymer system containing PEG 8000 and dextran T500. The PEG-modified monoclonal IgG was used as an affinity ligand in the two phase polymer system to specifically increase the partition of rabbit anti-NN glycophorin A IgG. The rabbit IgG was used together with the PEG-modified monoclonal IgG to increase the partition of human erythrocytes. The same system had no effect on rabbit erythrocytes. In summary, it was demonstrated that a monoclonal antibody can be modified and used to alter cell partition in two phase aqueous polymer systems in an immunologically specific manner.
Science, Faculty of
Chemistry, Department of
Graduate
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28

Nickl, Kathrin. "Establishment of functional cannabinoid receptor test systems and evaluation of ligands derived from Echinacea pallida." kostenfrei, 2008. http://www.opus-bayern.de/uni-regensburg/volltexte/2008/989/.

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29

Olszak, Torsten Michael. "Expression, Signaltransduktion und biologische Funktionen des CCL20/CCR6-Chemokin-Ligand-Rezeptor-Systems in intestinalen Epithelzellen." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-78674.

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30

Stokes, Emily C. "Amphiphilic ligand architectures for s-, d- and f-block metallosurfactants towards micellar systems and microemulsions." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/106671/.

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The design, synthesis and characterisation of a range of surfactant-based ligand architectures is presented. The amphiphilic ligands have been shown to form metallosurfactants with a wide range of s-, d- and f-block metals as well as being able to form stable micellar systems either through self-assembly or via doping into a carrier microemulsion. The overall aim of this work was to produce surfactant ligands capable of sequestering metal ions and localising them on the surface of micellar droplets within an oil-in-water microemulsion. Chapter Two investigates the formulation and characterisation of a 1-alkyl-3-methyl imidazolium based micellar system capable of forming stable microemulsions with extremely high oil loadings as well as acting as a carrier for more complex surfactants. This chapter also describes the synthesis and characterisation two novel macrocyclic ligand architectures designed to coordinate a range of s-, d- and f-block metals to form a series of metallosurfactants capable of aggregation in aqueous media. Chapter Three explores an array of acyclic surfactant ligands synthesised from ethylene diamine and diethylene triamine precursors and functionalised with poly-alcohol arms. These amphiphilic ligands were coordinated to Ni(II) and Cu(II) in order to gain insight into their coordination geometries via photophysical studies. Tensiometric investigations of the free ligands and their Sr(II) and Y(III) metallosurfactants assessed their microemulsion compatibility as alternatives to macrocyclic architectures. Chapter Four presents a series of cationic bis-cyclometallated Ir(IIII) complexes where the diimine ligand is a bipyridine species functionalised with a lipophilic alkyl chain and the cyclometallating ligands contain ethyl ester moieties which, upon deprotection, afford water soluble complexes. Combined tensiometric and photophysical studies found these species to be dual emissive as free complexes in solution, with emission arising from both ligand-centred and metal-to-ligand charge transfer mechanisms. Upon aggregation into micelles however, either a quenching of the ligand-centred emission or an enhancement of the metal-to-ligand charge transfer rendered the complexes mono-emissive. Chapter Five reports the synthesis and characterisation of three novel DO3A-based surfactant ligands incorporating pendent chromophores as antennae for near-IR sensitised emission from a range of Ln(II) ions. Luminescent lifetime studies determined that the ligands form 8-coordinate complexes with hydration states suggesting the presence of 0-1 inner sphere water molecules. Combined tensiometric and photophysical studies proved the metallosurfactants to be capable of self-assembly into micelles in aqueous media and found aggregation to have a notable effect on the local environment of the Ln(III) ions.
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31

OBAIDULLAH, AHMAD J. "USING HYDROPATHIC MOLECULAR MODELING TOOLS TO ENHANCE UNDERSTANDING OF PROTEIN-LIGAND INTERACTIONS IN BIOLOGICAL SYSTEMS." VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5156.

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Hydropathic molecular modeling is a computer-aided molecular design technique for obtaining, representing, and understanding the properties and interactions of biomacromolecular complexes in the biological environment. Hydropathic INTeraction (HINT) is a novel empirical force field to calculate the free energy of intermolecular interaction based on experimentally determined partition coefficients (log Po/w). It includes all the expected interactions between molecules such as hydrogen bonding, hydrophobic, electrostatic, acid-base, and Coulombic interactions, entropy, solvation and others. HINT tools were used to determine, evaluate, and analyze protein-ligand interactions in different research projects: 1) We used these tools to discover small molecule inhibitors of PsaA, a potential target for Streptococcus pneumoniae. We screened and scored potential molecules to obtain hits. After the growth conditions for both the wild type and PsaA mutant of S. pneumoniae were optimized, we then tested our hits. A few compounds passed through the three-stage assay protocol and confirmed the inhibition of PsaA with MICs between 125-250 μM. 2) The SAR of C-3 and C-5 pyrrole-based antitubulin agents at the colchicine-binding site with explicitly solvated models was performed. After docking with GOLD at the colchicine site, post-docking scoring and evaluation were performed with HINT. The total HINT score correlates with binding and activity; similarly, the significance of individual functional groups, protein residues and interactions amongst a collection of compounds can be quantitated. The possibility of water-mediated interactions in a way solvent accessible part of the pocket was considered by subjecting molecular models to MD simulations. Several water molecules were identified to be contributing to the binding and were confirmed by HINT scoring. Finally, using hydropathic molecular modeling tools helped us to understand, evaluate, analyze, and improve protein-ligand interactions in different biological systems.
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32

Pliotas, Christos. "Using biophysical techniques to study the mechanism of ligand-gated potassium efflux systems (KEF) from bacteria." Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=165422.

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The ligand-gated potassium channels KefC and KefB of Escherichia coli are critical components in protecting cells from toxic electrophiles.  Potassium efflux through these channels is coupled to a decrease in cytoplasmic pH which in turn reduces the damage to DNA by electrophiles.  KefC and KefB are both inhibited by cytoplasmic glutathione and activated by glutathione adducts, such as ESG, formed by conjugation of glutathione with electrophilic compounds. Robust membrane purification protocols were developed to isolate both the wild type full-length KefC and KefB and the mutants required for biophysical analysis.  In vivo K+ measurements were performed to ensure that all of the constructs used were fully functional.  Structural and functional analysis used electron paramagnetic resonance (EPR) and stead state emission fluorescence measurements in vivo, on wild type and mutated full-length proteins to elucidate the gating mechanism and test the model generated from crystallographic data.  In particular, EPR spectroscopy combined with site-directed spin labelling revealed a substantial conformational change and thus provided the first insight into coupling between sensing and gating.  Steady state fluorescence spectroscopy was used to precisely measure binding affinities for both activating and inhibitory ligands and characterise nucleotide binding to KefC.  Finally, a variety of chemically diverse glutathione adducts was tested on KefC in vitro to elucidate the mechanism by which these ligands initiate K+ flux through the associated transmembrane domain.
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33

Deitinghoff, Lutz Alexander [Verfasser]. "Identifizierung und Charakterisierung eines neuen Ligand-Rezeptor-Systems der retinotectalen Projektion / vorgelegt von Lutz Alexander Deitinghoff." Tübingen, Danziger Str. 21 : L. A. Deitinghoff, 2003. http://d-nb.info/969759088/34.

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34

Habermeyer, Benoit. "Synthèse et études physico-chimiques de complexes trimétalliques flexibles en séries bisporphyriniques." Thesis, Dijon, 2011. http://www.theses.fr/2011DIJOS025.

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Motivé par leur implication dans le centre réactionnel de l’appareil photosynthétique, puis plus tard, par les défis de la catalyse par transfert multi–électronique, des exemples d'édifices composés de deux porphyrines maintenues face–à–face apparaissent dans les années 70. Les premiers exemples font appel à l’utilisation d’espaceurs rigides qui maintiennent les porphyrines selon une géométrie bien définie permettant d’établir des relations précises entre la structure et les propriétés de ces dérivés. Ce projet de recherche a consisté à synthétiser une « nouvelle génération » de systèmes Pacman, plus flexibles et présentant deux types de conformations : une ouverte et une fermée. En ce sens, ces dérivés peuvent être décrits comme des pinces moléculaires. Le passage d’une conformation à l’autre serait contrôlé par la coordination d’un cation métallique au sein d’un espaceur–ligand. La conformation du système ne dépendrait alors plus de l’espaceur mais serait imposée par la géométrie de coordination du métal. Outre le contrôle conformationnel en fonction de la nature du cation métallique, l’avantage de cette approche est de pouvoir moduler, ou réguler dans le cas d’une coordination réversible, les propriétés physico–chimiques du système par simples interactions de type hôte/invité. Alors que les porphyrines sont supposées se comporter indépendamment dans la forme ouverte, la fermeture de la pince devrait se traduire par un rapprochement des macrocycles selon une disposition cofaciale impliquant des interactions entre les porphyrines. Ainsi, une modification des propriétés physico–chimiques de l’espèce et de son activité est attendue de par la communication électronique et/ou la coopérativité intermétallique établie. Nous nous sommes attachés également à présenter les études physico–chimiques entreprises sur certains systèmes bi– et trimétalliques afin de valider ces différents concepts
Motivated by their involvement in the reaction center of the photosynthetic apparatus, and later, by the challenges of the multi–electron transfer catalysis, some examples of porphyrin dimer maintained in a face–to–face arrangement, appeared in the seventies. The first examples consisted in rigid spacers, which maintain the porphyrins in a well–defined geometry in order to establish a precise relationship between the structure and the properties of these derivatives. This research project consists in the synthesis of a “new generation” of Pacman systems, more flexible and presenting two types of conformations: one open, the other closed. In this way, these derivatives can be described as molecular tweezers. The way to go from one conformation to the other would be controlled by the coordination of a metal cation within a spacer–ligand. Thus, the conformation of the system will not depend on the spacer (like in the previous Pacman systems) but would be determined by the metal coordination geometry. In addition to the conformational control as a function of the nature of the metal cation, the advantage of this appraoch is to modulate, or regulate in the case of a reversible coordination, the physico–chemical properties of the system by simple host/guest interactions. Although the porphyrins are supposed to act independantly in the open form, the closure of the tweezer would bring the macrocycles closer according to a cofacial arrangement involving interporphyrinic interactions. Thus, a modification of the physico–chemical properties and the activity of the species is expected by the electronic communication between both macrocycles and/or the established bimetallic cooperativity. In order to validate these concepts, physico–chemical studies performed on some bis– and tris–metal systems are described
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35

Franks, David John. "Investigating constitutive activity in G-protein coupled receptors and the effects of prolonged ligand treatments on receptor systems." Thesis, University of Reading, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427857.

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36

Sommer, Samantha. "Hybrid Metal-Ligand Hydrogen-Bonded (MLHB) Architectures Based on the Quinolone Subunit: Understanding and Expanding the Accessible Space of Supramolecular Systems." Thesis, University of Oregon, 2015. http://hdl.handle.net/1794/19298.

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Despite the prevalence of supramolecular architectures derived from metal-ligand or hydrogen-bonding interactions, few studies have focused on the simultaneous use of these two strategies to form discrete metal-ligand hydrogen-bonded (MLHB) assemblies. The design, synthesis, and characterization of 2-quinolone based hybrid subunits, 7-DPQ and 5-PYQ, that contain phosphine and pyridyl metal binding sites, respectively, is reported. Both subunits give two-fold symmetric hydrogen-bonded tectons that assemble with metal precursors to give hybrid MLHB structures. Treatment of [Cp*RhCl2]2 with the 7-DPQ subunit yields hybrid MLHB assemblies with closed topology. 1H diffusion ordered spectroscopy experiments established the stability of the structures in solution, and the measured hydrodynamic radii match those determined crystallographically, suggesting that the closed topology is maintained in solution and the solid state. In order to further explore possible MLHB architectures and test the selectivity boundaries of our quinolone-based subunits we report the selective assembly of 5-PYQ with mono- and bis-platinated anthracene precursors. Addition of 5-PYQ to [1-trans-Pt(PEt3)2NO3]-8-chloroanthracene yielded a hybrid MLHB structure with preorganization for a hybrid MLHB polymer. Despite the systems preorganization for the hybrid polymeric structure the assembly of 5-PYQ with 1,8-bis(trans-Pt(PEt3)2NO3)anthracene selects only for one discrete closed self-assembled macrocycle. The strong π-π stacking interactions of the 5-PYQ subunits erode the hydrogen-bonding fidelity to favor ambidentate coordination modes of 5-PYQ and give the non-hybrid macrocycle. In the course of investigating the intricacies of hybrid MLHB supramolecular structures we observed that, in addition to metal-ligand and hydrogen-bond interactions, the π-π stacking interactions of the 7-DPQ and 5-PYQ subunits played a critical role in determining the final assemblies. In fact, the prominent π-π interactions were typically found to be more favorable than the quinolone interligand hydrogen-bonding interactions. These results contribute to the overall knowledge of the design principles, synthesis, characterization, and fundamental assembly trends when exploiting both hydrogen-bonding and metal-ligand interactions to form stable supramolecular architectures. These studies have provided the foundation for expanding the accessible space of supramolecular chemistry to include rationally designed hybrid MLHB systems to give structures that more closely mimic the complex supramolecular systems observed in Nature. This dissertation includes both previously published/unpublished and co-authored material.
10000-01-01
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37

Castillo-Montoya, Javier, and Javier Castillo-Montoya. "Development of Orthogonal Split-Kinase and Split-Phosphatase Systems for Interrogating and Rewiring Signal Transduction." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/623179.

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The function of most proteins is regulated by post-translational modifications, of which phosphorylation in particular has been shown to be ubiquitous and of paramount importance to cell signaling. Two enzyme families, protein kinases and phosphatases, regulate phosphorylation, and aberrant activities of family members have been implicated in many diseases such as cancer and neurological disorders. Thus, understanding the function of these enzymes in living cells is important for understanding their biology and for designing new therapies, but a challenging task due to their highly conserved architecture. The major focus of the dissertation is on the development of a new approach to selectively turn-on multiple specific kinases and/or phosphatases using orthogonal ligands as chemical inducers of dimerization (CIDs). Specific kinases or phosphatases were dissected at particular sites into two inactive fragments or split-proteins. The split fragments are attached to interacting protein pairs of CID systems, such that upon addition of the specific ligand they heterodimerize with subsequent reassembly of the split-protein and concomitant activity. We demonstrated the in vitro and in cellulo feasibility of this approach using three orthogonal CIDs, rapamycin, abscisic acid, and gibberellic acid, to turn-on members of the tyrosine kinase group such as Lyn and Src, and of the tyrosine phosphatase group such as PTP1B and SHP1. We have also developed a new synthetic photocleavable di-trimethoprim CID that allows for ligand-gated turn-on of desired kinases in live cells. The new CID can be cleaved or turned-off by UV irradiation which results in a turn-off of kinase activity. Small molecule controlled split-proteins allow for developing logic gates and we demonstrate that the systems we have developed can be used to construct 7 out of the 10 basic, circuit-type Boolean phosphorylation-based logic gates in living cells. These post-translational logic gates may have interesting applications in synthetic biology. Finally, we present an initial approach to use redesigned kinases and redesigned ligands as potential scaffolds for developing new CIDs. Thus, we provide and extend new methodologies that potentially allow for posttranslational control over the activity of user defined split-kinases and split-phosphatases for interrogating and redesigning signaling pathways. The last section of this work focuses on understanding small-molecule selectivity toward protein kinases. We systematically analyzed different reported kinase screens to further understand the reliability of large scale data in the kinome field as the design of selective inhibitors is one the most useful approaches for understanding the function of enzymes or the development of drugs in a natural setting such as a primary cell or an organism.
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38

Landgraf, Corina [Verfasser], and Florian [Akademischer Betreuer] Beigel. "Die Bedeutung des OSM/OSMR-Zytokin-Ligand-Rezeptor-Systems in intestinalen Epithelzellen und bei intestinaler Entzündung / Corina Landgraf ; Betreuer: Florian Beigel." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2018. http://d-nb.info/1155097564/34.

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39

Fortin, Ensign Shannon Patricia. "The TWEAK-Fn14 Ligand Receptor Axis Promotes Glioblastoma Cell Invasion and Survival Via Activation of Multiple GEF-Rho GTPase Signaling Systems." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293463.

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Glioblastoma (GB) is the highest grade and most common form of primary adult brain tumors, characterized by a highly invasive cell population. GB tumors develop treatment resistance and ultimately recur; the median survival is nearly fifteen months and importantly, the invading cell population is attributed with having a decreased sensitivity to therapeutics. Thus, there remains a necessity to identify the genetic and signaling mechanisms that promote tumor spread and therapeutic resistance in order to develop new targeted treatment strategies to combat this rapidly progressive disease. TWEAK-Fn14 ligand-receptor signaling is one mechanism in GB that promotes cell invasiveness and survival, and is dependent upon the activity of multiple Rho GTPases including Rac1. Here, we show that Cdc42 is essential in Fn14-mediated Rac1 activation. We identified two guanine nucleotide exchange factors (GEFs), Ect2 and Trio, involved in the TWEAK-induced activation of Cdc42 and Rac1, respectively, as well as in the subsequent TWEAK-Fn14 directed glioma cell migration and invasion. In addition, we characterized the role of SGEF in promoting Fn14-induced Rac1 activation. SGEF, a RhoG-specific GEF, is overexpressed in GB tumors and promotes TWEAK-Fn14-mediated glioma invasion. Moreover, we characterized the correlation between SGEF expression and TMZ resistance, and defined a role for SGEF in promoting the survival of glioma cells. SGEF mRNA and protein expression are regulated by the TWEAK-Fn14 signaling axis in an NF-kB dependent manner and inhibition of SGEF expression sensitizes glioma cells to TMZ treatment. Lastly, gene expression analysis of SGEF depleted GB cells revealed altered expression of a network of DNA repair and survival genes. Thus TWEAK-Fn14 signaling through the GEF-Rho GTPase systems which include the Ect2, Trio, and SGEF activation of Cdc42 and/or Rac1 presents a pathway of attractive drug targets in glioma therapy, and SGEF signaling represents a novel target in the setting of TMZ refractory, invasive GB cells.
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40

Fortin, Ensign Shannon Patricia. "THE TWEAK-FN14 LIGAND RECEPTOR AXIS PROMOTES GLIOBLASTOMA CELL INVASION AND SURVIVAL VIA ACTIVATION OF MULTIPLE GEF-RHO GTPASE SIGNALING SYSTEMS." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/528171.

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A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine.
Glioblastoma (GB) is the highest grade and most common form of primary adult brain tumors, characterized by a highly invasive cell population. GB tumors develop treatment resistance and ultimately recur; the median survival is nearly fifteen months and importantly, the invading cell population is attributed with having a decreased sensitivity to therapeutics. Thus, there remains a necessity to identify the genetic and signaling mechanisms that promote tumor spread and therapeutic resistance in order to develop new targeted treatment strategies to combat this rapidly progressive disease. TWEAK-Fn14 ligand-receptor signaling is one mechanism in GB that promotes cell invasiveness and survival, and is dependent upon the activity of multiple Rho GTPases including Rac1. Here, we show that Cdc42 is essential in Fn14-mediated Rac1 activation. We identified two guanine nucleotide exchange factors (GEFs), Ect2 and Trio, involved in the TWEAK-induced activation of Cdc42 and Rac1, respectively, as well as in the subsequent TWEAK-Fn14 directed glioma cell migration and invasion. In addition, we characterized the role of SGEF in promoting Fn14-induced Rac1 activation. SGEF, a RhoG-specific GEF, is overexpressed in GB tumors and promotes TWEAK- Fn14-mediated glioma invasion. Moreover, we characterized the correlation between SGEF expression and TMZ resistance, and defined a role for SGEF in promoting the survival of glioma cells. SGEF mRNA and protein expression are regulated by the TWEAK-Fn14 signaling axis in an NF-B dependent manner and inhibition of SGEF expression sensitizes glioma cells to TMZ treatment. Lastly, gene expression analysis of SGEF depleted GB cells revealed altered expression of a network of DNA repair and survival genes. Thus TWEAK-Fn14 signaling through the GEF-Rho GTPase systems which include the Ect2, Trio, and SGEF activation of Cdc42 and/or Rac1 presents a pathway of attractive drug targets in glioma therapy, and SGEF signaling represents a novel target in the setting of TMZ refractory, invasive GB cells.
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41

Magee, Chad Leroy Keller S. W. "The synthesis and characterization of 1,1'-disubstituted ferrocene imine Schiff base ligand systems for use as potential environmental heavy metal cationic sensors." Diss., Columbia, Mo. : University of Missouri--Columbia, 2008. http://hdl.handle.net/10355/7117.

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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 23, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dr. Steven W. Keller, Dissertation Supervisor. Vita. Includes bibliographical references.
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42

Silver, Nathaniel White. "Ensemble methods in computational protein and ligand design : applications to the Fc[gamma] immunoglobulin, HIV-1 protease, and ketol-acid reductoisomerase systems." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/73372.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2012.
In title on title-page, "[gamma]" appears as the lower-case Greek letter. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 170-192).
This thesis explores the use of ensemble, free energy models in the study and design of molecular, biochemical systems. We use physics based computational models to analyze the molecular basis of binding affinity in the context of protein-protein and protein-ligand binding as well as reaction rate enhancement in enzyme catalysis. First, we evaluate the solvent screened energetics of immunoglobulin G (IgG):Fc[gamma] receptor binding using molecular mechanics, Poisson-Boltzmann surface area (MMPBSA) models. We assess the role IgG1 linked glycans play in binding to human Fc[gamma]-III and computationally evaluate experimentally designed Fe mutations that recover binding affinity in the absence of glycosylation. Using the insight gained from this study, we developed novel murine IgG variants with engineered Fc[gamma] receptor binding patterns via the computational design and experimental validation of Fc mutations that are predicted to knock out binding to Fc[gamma]R-IV. Our design and analysis highlight the importance of solvent screened electrostatic interactions and electrostatic complementarity in protein-protein binding. Second, we develop novel, ensemble methods to measure configurational free energy and entropy changes in protein-ligand binding and use it to predict the relative binding affinity of a series of previously designed HIV-1 protease inhibitors. We find that using configurational free energies to evaluate inhibitor efficacy significantly improves relative ranking of inhibitors over traditional, single-point energy metrics, but that only a relatively small number of low energy configurations are necessary to capture the ensemble effect. Finally, we present a joint study of the redesign and dynamic analysis of ketol-acid isomeroreductase (KARI). We first develop and apply a novel, end-point method to rationally design enzyme variants that reduce the free energy of activation, and present the computational and experimental analysis of a series of designed KARI mutants. Our analysis reveals that this transition-state theory based approach is effective at reducing the enthalpy of activation, but also increases entropic activation penalties that ultimately overpower the enthalpic gains. A dynamic analysis of these KARI variants is also presented, in which the transition path ensemble is explored using transition path sampling. We find that this ensemble approach is better able to predict relative enzyme activities and suggests a conserved, dynamic mechanism for catalysis. The results and analysis presented herein demonstrate novel, computational approaches to account for ensemble effects in the study and design of effective biomolecules.
by Nathaniel White Silver.
Ph.D.
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43

Kamara, Lamin Mohamed. "Chiral Sulfinamides, n-Oxides & B-Diketimines as Lewis Base Catalysts and Lewis Bases in Synthetic Reactions; the Development of New Ligand Systems." Thesis, University of Sussex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506938.

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44

Bronova, Anna [Verfasser]. "BonnMag a Computer Program for Angular Overlap Modeling of all fn-Systems: New Insights into Ligand-field splitting of Lanthanide and Actinide ions / Anna Bronova." Bonn : Universitäts- und Landesbibliothek Bonn, 2018. http://d-nb.info/1163662364/34.

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45

Kneiseler, Guntje [Verfasser]. "Die funktionelle Bedeutung des Fas-, Fas-Ligand-Systems bei der Immunpathogenese der Sepsis : Untersuchungen zu Promotorpolymorphismen des Fas-Rezeptors bei Patienten mit schwerer Sepsis / Guntje Kneiseler." Bonn : Universitäts- und Landesbibliothek Bonn, 2011. http://d-nb.info/1016180667/34.

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46

Wurmthaler, Lena Amelie [Verfasser]. "Influence of ribozyme cleavage in E. coli expression systems and the utilization of ligand-dependent ribozymes for conditional genetic control in C. elegans / Lena Amelie Wurmthaler." Konstanz : KOPS Universität Konstanz, 2018. http://d-nb.info/1219852635/34.

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47

Kuonen, Oliver Dominik. "De novo design, molecular dynamics simulations and ab initio calculations as tools to investigate biological systems : a critical application of the Molecular Modeling approach in ligand design /." Zürich : ETH, 1997. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=12370.

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48

Barry, Seán Thomas. "Compounds with mixed ligand systems as precursors for thermal synthesis of III-V extended solids, halo-pnictido, alkyl-pnictido, and siloxo-pnictido complexes of gallium and indium." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq20991.pdf.

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49

Barry, Sean Thomas. "Compounds with mixed ligand systems as precursors for thermal synthesis of III-V extended solids: Halo-pnictido, alkyl-pnictido, and siloxo-pnictido complexes of gallium and indium." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/9614.

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The compounds MN(SiMe$\rm\sb3)\sb2Cl\sb2\cdot$base (1: M = Ga, base = thf; 2: M = In, base = pyridine) were synthesised. Compound 1 disproportionated to gallium trichloride while 2 did not show any thermal reactivity. The compounds (Ga(R)$\sb2$N(SiMe$\sb3)\sb2\rbrack\sb2$ (3: R = $\rm\sp{n}$Bu, 4: R = $\rm\sp{t}$Bu) were synthesised. Complex 4 decomposed into several products at 400$\sp\circ$C, while 3 thermolysed to form hexagonal GaN at 400$\sp\circ$C, after annealing at 900$\sp\circ$C. Phosphido analogues of these, $\rm\lbrack Ga(\sp{n}Bu)(R)P(SiMe\sb3)\sb2\rbrack\sb2$ (5: R = $\rm\sp{n}$Bu, 6: R = Cl) as well as (($\rm\sp{n}Bu)\sb2InP(SiMe\sb3)\sb2\rbrack\sb2$ (7) were synthesised. Complex 5 thermally rearranged to GaP at 250$\sp\circ$C. NMR studies determined that although the side product $\rm Me\sb3SiCl$ was formed in the thermolysis of 6, several products resulted and the desired phosphinido was isolated. The thermolysis of 7 at 400$\sp\circ$C produced both InP and In$\sp0.$ A series of primary amido gallium alkyl complexes: $\rm\lbrack\sp{t}Bu\sb2Ga(\mu$-N(H)$\rm\sp{t}Bu)\rbrack\sb2$ (8), $\rm\lbrack\sp{n}Bu\sb2Ga(N(H)\sp{t}Bu)\rbrack\sb2$ (9), $\rm\sp{n}Bu\sb2Ga\lbrack NH$(2.6-$\rm Me\sb2C\sb6H\sb3)1py$ (10) and $\rm\sp{n}Bu\sb2Ga\lbrack NH$(2,6-$\rm Me\sb2C\sb6H\sb3)\rbrack\sb2\lbrack Li(Et\sb2O)\rbrack$ (11) were synthesised.. Thermolysis of 8 at 120$\sp\circ$C gave a compound which $\sp1$H NMR characterisation suggested was $\rm\lbrack\sp{t}BuGaN\sp{t}Bu\rbrack\sb{x},$ but the extreme air sensitivity of this compound precluded characterization. Compound 9 was robust to thermolysis. Compounds 10 and 11 formed many products upon thermolysis at 170$\sp\circ$C and 155$\sp\circ$C respectively. The siloxide compounds M(OSiMe$\sb3)\sb{3-x}Cl\sb{x}\cdot$py (12: M = Ga, X = 0; 13: M = Ga, X = 1, 14: M = In, X = 0; 15: M = In, X = 1) were synthesised. All demonstrated elimination of $\rm(Me\sb3Si)\sb2O$ as determined by $\sp1$H NMR and MS, with only 12 forming any undesirable side-products. Thermolysis products were not isolated. A series of trimethylsilylamido-siloxo complexes: $\rm Ga(N(SiMe\sb3)\sb2)(OSiMe\sb3)\sb2py$ (17), $\rm\lbrack Li(thf)\sb2\rbrack\lbrack Ga(N(SiMe\sb3)\sb2)(OSiMe\sb3)\sb2Cl\rbrack$ (16), $\rm\lbrack Li(py)\sb2\rbrack\lbrack In(N(SiMe\sb3)\sb2)(OSiMe\sb3)\sb2Cl\rbrack$ (18), and $\rm\lbrack Li(py\sb2\rbrack\lbrack In(N(SiMe\sb3)\sb2)(OSiMe\sb3)\sb3\rbrack$ (19) were synthesised. 17 thermolised to a grey powder, which evolves into hexagonal GaN upon heating at 900$\sp\circ$C. Thermolysis experiments of compounds 16, 18, and 19 indicate a more complex rearrangement process than for 17; they do not proceed smoothly to yield the III-V nitride. Lastly, $\rm\lbrack In(N(SiMe\sb3)\sb2)(\mu\sp2$-$\rm O)\rbrack\sb{x},$ (20) was prepared from hexane in the absence of coordinating base. It was characterised by $\sp1$H NMR, elemental analysis and MS, but its crystallinity precluded a single-crystal XRD to establish the extent of oligomerisation.
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50

González, Miera Greco. "Homogeneous and heterogeneous Cp*Ir(III) catalytic systems : Mechanistic studies of redox processes catalyzed by bifunctional iridium complexes, and synthesis of iridium-functionalized MOFs." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-143343.

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The purpose of this doctoral thesis is to investigate and develop catalytic processes mediated by iridium(III) complexes. By understanding the mechanisms, the weaknesses of the designed catalysts can be identified and be overcome in the following generation. The thesis is composed of two general sections dedicated to the synthesis and applications of homogeneous catalysts and to the preparation of heterogeneous catalysts based on metal-organic frameworks (MOFs). After a general introduction (Chapter 1), the first part of the thesis (Chapters 2-4, and Appendix 1) covers the use of several homogeneous bifunctional [Cp*Ir(III)] catalysts in a variety of chemical transformations, as well as mechanistic studies. Chapter 2 summarizes the studies on the N-alkylation of anilines with benzyl alcohols catalyzed by bifunctional Ir(III) complexes. Mechanistic investigations when the reactions were catalyzed by Ir(III) complexes with a hydroxy-functionalized N-heterocyclic carbene (NHC) ligand are discussed, followed by the design of a new generation of catalysts. The chapter finishes presenting the improved catalytic performance of these new complexes.    A family of these NHC-iridium complexes was evaluated in the acceptorless dehydrogenation of alcohols, as shown in Chapter 3. The beneficial effect of a co-solvent was investigated too. Under these base-free conditions, a wide scope of alcohols was efficiently dehydrogenated in excellent yields. The unexpected higher activity of the hydroxy-containing bifunctional NHC-Ir(III) catalysts, in comparison to that of the amino-functionalized one, was investigated experimentally. In the fourth chapter, the catalytic process presented in Chapter 3 was further explored on 1,4- and 1,5-diols, which were transformed into their corresponding tetrahydrofurans and dihydropyrans, respectively. Mechanistic investigations are also discussed. In the second part of the thesis (Chapter 5), a Cp*Ir(III) complex was immobilized into a MOF. The heterogenization of the metal complex was achieved efficiently, reaching high ratios of functionalization. However, a change in the topology of the MOF was observed. In this chapter, the use of advanced characterization techniques such as X-ray absorption spectroscopy (XAS) and pair distribution function (PDF) analyses enabled to study a phase transformation in these materials.

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Submitted.

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