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Showing 1 to 20 of 223 for “"Protonation"”.
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Protonation and Membrane Protein Function
… forces that drive these reactions. The protonation state of a titratable residue embedded in a protein environment can differ from its default value in bulk water at neutral pH. It is thus necessary to correctly evaluate its protonation state in order to generate meaningful reaction …
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Synthesis of molybdenum olefin metatheses catalysts through protonation reactions
The attempted syntheses of molybdenum imido alkylidene complexes of the type Mo(NArc,)(CH-t-Bu)[Biphen] and Mo(N-2-CF3C6H4)(CHCMe2Ph)[Biphen] (Biphen2 = 3,3'-di-t-butyl-5,5',6,6'-tetramethyl- 1,1'-biphenyl-2,2'-diolate) from Mo(NArcl)(CH-t-Bu)(OTf)2(dme) and [Biphen]K2 have sporadically afforded …
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Small molecule mimics of hydrogenase enzymes: synthesis, protonation, and electrocatalysis
… models have been prepared, many of which undergo protonation to form hydride complexes and catalyze proton reduction. However, in all cases, the thermodynamic product of protonation is a bridging hydride, which is not biologically relevant. A number of phosphine substituted diiron complexes have …
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A computer simulation of the protonation and metal complexation properties of fulvic acids
… electrostatic models are incorporated into protonation and metal complexation models of fulvic acids. Parameters which may influence simulated results to a large extent are identified. This investigation indicates that input parameters for the various modelling steps should be chosen with a …
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Understanding the effect of protonation on the self-assembly of a model polyelectrolyte-neutral block copolymer
… X-ray scattering. First, the ability of P2VP protonation to change the morphology of the diblock is demonstrated; while miscible in the absence of charge, the diblock undergoes a disorder to order transition upon protonation by a variety of acids. Thin films with varying levels of …
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I. Enthalpy of Protonation Studies on Selected Organolithium Compounds. Ii. Dipole Stabilized Carbanions in N-Methyl Carboxamides
Made available in DSpace on 2014-12-13T20:10:04Z (GMT). No. of bitstreams: 1 7714930.pdf: 5080318 bytes, checksum: cf7b65bfc5e248c32aa17b9119ac4f66 (MD5) Previous issue date: 1977
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Low-temperature protonation studies of an electron-poor osmium methyl complex, and molecular precursors for the construction of graphene nanostructues with atomically precise edge structures
… by beta-hydrogen elimination. Protonation of (C5Me5)Os(dfmpm)Me with (CF3SO2)2NH at –110 °C in CDCl2F yielded the methane coordination complex [(C5Me5)Os(dfmpm)CH4][N(SO2CF3)2]. The analogous 13CH4 complex exhibited a binomial quintet in the 13C NMR with a coupling constant (127 …
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Low-temperature protonation studies of transition metal alkyl complexes and the synthesis and characterization of early transition metal PCP pincer complexes and two-coordinate alkylamido complexes
… isotopically labeled analogs of Cp*Os(DFMPM)Et. Protonation of Cp*Os(DFMPM)Et with HOTf in CDCl2F at -130 °C affords the alkane complex [Cp*Os(DFMPM)(CH3CH3)][OTf]. The dissociation of the ethane ligand follows first-order kinetics characterized by activation parameters of ΔH‡ = 14.4 ± 4.2 …
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Structure-based theoretical characterisation of the redox-dependent titration behaviour of cytochrome bc1
… active sites, that catalyse the oxidation/deprotonation and reduction/protonation of CoQ, respectively. The two sites are located at opposite sides of the membrane. Their intricate chemistry is a matter of ongoing debate. This thesis describes a structure-based theoretical approach to …
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The Aggregation Behavior of Mixture of Alkylmethylaminoxides with Their Protonated Analogues in Aqueous Solution
… (L-alpha) phase was formed in the range of low protonation degree, X = 0.007 – 0.35. When the surfactant was protonated further (X > 0.35), the single L-alpha phase separated again into two isotropic phases. The abnormal phase sequence could be interpreted by the result that mixtures of …
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Pentamethylcyclopentadienyl Osmium Chemistry: An Approach to Transition Metal Alkane Complexes
Protonation of $\rm(C\sb5Me\sb5)Os(PMe\sb3)\sb2Me$ with $\rm HBF\sb4{\cdot}Et\sb2O$ at room temperature affords the Os$\sp{\rm IV}$ alkyl hydride complex $\lbrack\rm(C\sb5Me\sb5)Os(PMe\sb3)\sb2Me(H)\rbrack\lbrack BF\sb4\rbrack.$ Protonation of $\rm(C\sb5Me\sb5)Os(dmpm)Me$ at ${-}120\sp\circ$C with …
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Structure-function relationship of archaeal rhodopsin proteins analyzed by continuum electrostatics
… Here, the probability of functionally relevant protonation states is calculated to characterize the available structures. The protonation behavior of the key residues of proton transfer and the correlation between the protonation of these residues is analyzed. The results show that with respect …
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Studies of metaphosphate acids and metaphosphate anhydrides in aprotic media
… has previously been elusive in aqueous media. Protonation of imetaphosphates in organic media has resulted in six metaphosphate acids. X-ray diffraction studies display that the structural configurations of metaphosphate acids are dictated by strong hydrogen bonding interactions. As a …
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Protein and Water Modeling in Computer-Aided Drug Discovery
… a protein can adopt due to different rotamer and protonation states of its residues. This thesis explores advancements in CADD to address this challenge, focusing on protein modeling and water interactions.</p> <p>In Chapter 1, I introduce the drug discovery process with a brief overview of its …
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Visible light-induced pH control and its applications
… was used to explore the influence of the protonation state of the merocyanine form (MCH vs MC) on the photoswitching efficiency. A python model is developed to describe the pH- recovery in the dark. Chapter 3 introduces an improved merocyanine photoacid, designed by principles outlined in …
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A Continuum Electrostatic Approach for Calculating The Binding Energetics of Multiple Ligands
… system for parameterizing a site with several protonation and reduction forms. A complex site is also the CuB center in Cytochrome c oxidase, which is studied to decide if multiple protonation forms of the coordinating histidines are involved in the reaction mechanism. Factors influencing the …
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New Chemistry of Transition Metal Alkyls and Hydrides: Bonding and Reactivity
Protonation of the osmium(II) hydrides (C5Me5)Os(PR 3)2H with tetrafluoroboric acid affords the corresponding osmium(IV) dihydride complexes of stoichiometry [(C5Me5)Os(PR 3)2H2+], where PR3 = PMe3, PEt3, PPh3, 1/2 dmpe, 1/2 dmpm, 1/2 dppm, or 1/2 dpdtm (where dmpe = …
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Syntheses, structure and stability of some alkylphosphonic acids and their metal complexes.
The protonation end complexetion behaviour of the a-aminomethylenephosphonic acids diethylaminomethylenephonosphonic acid (DEAMPH2), N-ethyliminobis(methylenephosphonic acid) (NEIBMPH4), (+-)-trans-l,2-diaminecyclohexane tetrakis(methylenephosphonic acid) (CDTMPN8) and …
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Understanding MS/MS fragmentation pathways of small molecular weight molecules
… as a result of conformational changes induced by protonation. Bond length changes for a test set of molecules were calculated using quantum chemistry software. Density Functional Theory (DFT) or Austin Model 1 (AM1) or both were used to energy minimise the structures of the neutral molecules and …
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The extraction of trichlorostannato-rhodium complexes by polyurethane foam
… complex, [RhH(SnCl₃)₅]³⁻, which is formed by protonation of [Rh(SnCl₃)₅]⁴⁻. The protonation reaction has been shown to be reversible. The ¹¹⁹Sn nmr study showed the formation of a new rhodium-hydrido complex formulated to be [RhH(SnCl₃)₄Cl]³⁻. In the presence of low tin(II) concentrations …
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