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Showing 1 to 15 of 15 for “"Proton affinity"”.
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A Study of Fuel Conversion Chemistry
… 140K was utilized to investigate the degree of proton transfer reaction on a hydrogen-precovered surface. Pyridine, 3-fluoropyridine and 2-fluoropyridine are chosen as indicators. The MSAE of Pt(110) in proton affinity scale has been determined to be 907 +/- 4 kJ/mol using electron energy loss …
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Resonance Two Photon Ionization Study of Binary Clusters of Styrene with Polar Molecules
… of styrene. Size-specified intracluster proton transfer reactions were observed for mixed clusters of styrene dimer with water, methanol and ethanol molecules. It was proposed that the polar molecules tend to aggregate around the olefin center, which promotes the transfer of the charge …
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Synthesis and applications of functional magnetic polymer beads; synthesis and mass spectrometry analysis of model peptides
… solid phase peptide synthesis. The relative proton affinities of the model peptides were measured using the collision induced dissociation experiments using a triple quadrupole mass spectrometer. It was found that the effective proton affinity of a cyclic peptide was significantly reduced …
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Development of an electrospary ionization source and vacuum interface for guided ion beam tandem mass spectrometry experiments: structural and energetic effects in the molecular recognition of amino acids by 18-crown-6
… inverse correlation with the polarizability and proton affinity of the B and AA. Therefore, the ability of the n-terminal amino group to compete for 18C6 complexation is best for Gly and should become increasing less favorable as the size of the side chain substituent increases. </p> <p>The …
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Modeling Peptide-binding Interactions and Polymer-binding Interactions and their Role in Mass Spectrometry
… variations of entropies. Finally, the proton affinity of poly(methylmetacrylate) oligomers is being discussed. Even though no absolute values for the proton affinity were found, the experimental and computational results help to understand the variation that accompanies the oligomers …
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Chirale Sulfonimidamide und Sulfoximine : Synthese, Strukturuntersuchungen und Anwendungen
… shows structural similarities to so-called proton sponges. Protonation experiments towards the determination of the basicity were carried out and the kinetic activity of the bissulfoximine was determined in a proton self-exchange reaction. A discussion of the structures of the free base and …
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Measurement of Proton Transfer Reaction Rates in a Microwave Cavity Discharge Flowing Afterglow
… Reaction efficiency depends primarily upon the proton affinity of the molecules. All the measurements were obtained using the newly developed microwave cavity discharge flowing afterglow (MCD-FA) apparatus. This device uses an Asmussen-type microwave cavity discharge ion source that is spatially …
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First-principles molecular modeling of structure-property relationships and reactivity in the zeolite chabazite
… a negative charge, which can be compensated by a proton that acts as a strong, acid-donating Bronsted site. Zeolites are widely used in industry, most commonly for catalysis and separations. Unfortunately, they have not yet been able to replace all homogeneous catalysts in industrial processes due …
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Identities and Catalytic Functionalities of Reactive Hydrogen Species during Hydrogen Addition and Oxygen Removal Reactions of Carboxylic Acids, Carbonyls, and Phenols at Transition Metal-solvent Interfaces
… from H2 (10-60 bar) dissociative adsorption, and protons (H+) derived from either H* ionization or solvent self-ionization are catalytically reactive H species. These H species participate in or assist with hydrodeoxygenation of phenolics and carbonyls to produce alkanes and alkanols; yet their …
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Determination of the proton affinities of gas phase peptides by mass spectrometry and computational chemistry
… the effect of the helix confonnation on the proton affinities ofbasic amino acids placed at theN- or Ctenninus of helical model peptides in the gas phase. Several series of model peptides having a basic residue, lysine (K) or 2,3- diaminopropionic acid (Dap ), located at either terminus were …
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Mass spectrometric characterization of peptide radical ions and implication for radical chemistry
… species, sulfinyl radicals exhibit significant proton affinity due to the existence of heteroatoms. Evidence from experimental and theoretical studies clearly show that the duality of a sulfinyl radical to function as a radical or a base is affected by the neighboring amino acid side-chain …
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Very accurate gas-phase thermochemistry through photoelectron photoion coincidence (PEPICO) spectroscopy
… accurate heat of formation of CH 2 OH and the proton affinity of formaldehyde. The fourth project explores the dissociation pathways of cis -1-bromopropene, trans -1-bromopropene, 2-bromopropene, 3-bromopropene and bromocyclopropane to find that except for 2-bromopropene, all other isomers …
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Mechanistic Underpinnings of Efficient Chemical-to-Electrical Energy Interconversion in Bipolar Membranes
… the membrane voltage to a value dictated by the proton affinity of the conjugate acid/base. In addition, this neutralization product can undergo dissociation under reverse bias, reducing the Faradaic efficiency for the water dissociation reaction. Finally, in Chapter 4, we discover that, for BPM …
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STRUCTURE-FUNCTION STUDIES OF NOVEL MEDICALLY RELEVANT FLAVOENZYMES
… that implies α-OH hydrogen abstraction (as a proton) by the active site H373 followed by two-electron transfer to the flavin. The same studies revealed the presence of a water molecule (Wat609), conserved in all enzymes of the Fcb2 family and belonging to third shell residues, which may …
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Thermochemical differences in lysine and lysine-homolog containing oligopeptides: Determination of basicity and gas-phase structure through mass spectrometry, infrared spectroscopy, and computational chemistry
… di-, tri-, and tetra- peptides containing a proton-accepting probe: lysine and or the non-proteinogenic lysine-homologs: ornithine, 2,4-diaminobutyric acid, and 2,3-diaminopropionic acid. Peptides were studied in isomeric pairs for which the basic amino acid was placed closest to the …