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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 25 for “"Intramolecular Hydrogen bonding"”.
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Antimalarial benzimidazoles and related structures incorporating an intramolecular hydrogen bonding motif: medicinal chemistry and mechanistic studies
… and imidazopyridines, incorporating an intramolecular hydrogen bonding (IMHB) motif, were explored for their antimalarial potential. These two chemotypes were selected on account of their privileged nature due to their capacity to interact with various biological systems, leading to a …
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Electronic and solvent effects on monosaccharide conformations
… to solvent effects, stereoelectronic effects and hydrogen bonding; yet the experimentally obtained hydroxymethyl rotational populations have not yet been fully rationalised. In this dissertation, I have used a range of ab initio, Molecular Dynamics (MD), Quantum Mechanics/Molecular Mechanics …
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Electronic and solvent effects on monosaccharide conformations
… solvent effects, stereo-electronic effects and hydrogen bonding; yet the experimentally obtained hydroxymethyl rotational populations have not yet been fully rationalised. In this dissertation, I have used a range of ab initio, Molecular Dynamics (MD), Quantum Mechanics/Molecular Mechanics …
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Initial Studies on a Novel Target-Promoted DNA Alkylation System
… model systems (methoxyl polycyclic system, intramolecular hydrogen bonding system and biaryl system) were proposed and synthesized. The potential DNA QM alkylation was investigated by deoxyadenosine (dA) and deoxyguanosine (dG) alkylation with the biaryl system. Only one deoxynucleoside …
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Mechanistic studies of diastereoselective cyclopropanations of homochiral ene-ketals and synthesis and resolution of diastereomeric alpha-hydroxycycloalkanone ketals.
… is thought to result from differences in intramolecular hydrogen bonding for the two diastereomeric forms.
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Novel Organophosphorus Oligomers. Synthesis and conformation of α-hydroxy phenylphosphinates
… crystallography and computational methods shows intramolecular hydrogen bonding in these molecules depends on the relative configuration of the carbon and phosphorus atoms. However, although the development of the synthetic methods was successful, the separation and isolation of the diastereomers …
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The acetanilide crystal structures: packing and conformational similarities
… conformational analysis. Three amide-amide hydrogen bond geometries and a molecular stack were frequently observed in the acetanilides. The assembly of these one-dimensional packing features governs in particular the crystal structures of the para substituted acetanilides. The amide-amide …
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The study of proton-donor proton-acceptor interactions by infrared spectroscopy and computer modelling
… in CC14 and in the vapour phase in which a hydrogen-bonded complex is formed. In carbon tetrachloride, AHf^ = -15.3 kJ mol"1 and ASf"0" = -50.8 J mol"1 K" 1 . These values are consistent with data reported in the literature for related alcohols. Equilibrium constants for the vapour phase …
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An exploration of the solid-state architectures formed by 1,8-naphthyridine-2,7-dicarbonyl derivatives
… state, it was proposed that expansion of the hydrogen bonding array from three donor-acceptor pairs to four should increase the strength of the hydrogen-bonded array. Accordingly an investigation into the 1,8-naphthyridine-2,7-dicarbonyl derivatives has now been undertaken.<br/>Following the …
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A study of aromatic cyclodehydration, I. Ortho effects II. The catalytic effect of metal oxides
… was attributed to a second ortho effect due to intramolecular hydrogen-bonding between the hydroxy group and the keto group. Infrared spectroscopy demonstrated that this type of hydrogen-bonding is present. The 3'-hydroxy-2-benzylbenzophenone apparently cyclizes very readily since the 3'-methoxy …
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The chemical structure and mechanical properties of phenolic resins and related polymers
… based on phenol and para-cresol formulations. Intramolecular hydrogen bonding effects were examined using substituted resins and a synthetically derived phenol based on 1,3-di-(o-hydroxyphenyl) propane.. A resin system was developed using the Friedel Crafts reaction to examine inter-molecular …
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Mechanisms of Non-Enzymatic Peptide Bond Formation: Thioester and Transamidation Routes
… hydrolysis at neutral pH could be a result of intramolecular hydrogen bonding. Arrhenius and Eyring plots determined the energy of activation, activation enthalpy, and activation entropy to be 9.5 x 10-4 J mor1, 9.5 x 10-4 J mor1, and -1.5 x 10-5 J K-1 mor1, respectively. Both cellular and …
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Studies Toward A Detailed Understanding Of The Intrinsic Properties Of Nucleic Acid Constituents: Gas-Phase Conformations, Energetics, And Glycosidic Bond Stability
… IRMPD action spectra over the IR fingerprint and hydrogen-stretching regions. </p> <p>Theoretical calculations were performed using both mechanic dynamics and high level quantum chemical calculations to optimize structures, compute vibrational frequencies and IR intensities, and to obtain the …
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NMR Sensing Strategies Based on Modulation of Chemical Exchange Rate With Small-Molecule Synthetic Sensors
… (TUC) displaying conformational rigidity due to intramolecular hydrogen bonding. With an increase in chemical exchange rate, due to anion-induced conformational flexibility, detection and quantification of spherical and tetrahedral anions as low as 120 nM concentrations, which is more than 1000 …
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Determination of the proton affinities of gas phase peptides by mass spectrometry and computational chemistry
… by the protonated peptides due to extensive intramolecular hydrogen bonding. The measured proton affinities of the peptides increased with the size of the peptide as expected. However, the measured proton affinity of the peptide with C-terminal lysine, Ac-AK, is substantially higher than that …
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Conformational Studies on Alicyclic Alcohols
It is well known that intermolecular hydrogen-bonding is concentration dependent. It is also known that the H chemical shift of an hydroxyl proton is dependent upon concentration. H NMR spectroscopy has therefore been used to study hydrogen-bonding in solution.<br/><br/>It was found previously by …
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Structural basis for the design of selective complexing agents for transition metals
… reassemble macrocyclic systems, due to effective intramolecular hydrogen bonding linking the two ligands. To correlate chelating properties with intramolecular H-bond strengths an X-ray structural analysis was carried out on one ligand supplied by ICI, and thought to be 3,5-dimethyl-2-hydroxy …
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Chemical Studies of some Fungi
… in rings A and B in the mass spectrum. Strong intramolecular hydrogen bonding observed in the i.r. spectrum supported the equatorial conformation of the hydroxy group at Cl whilst the facile loss of water upon electron impact and the presence of a signal corresponding to an equatorial carbinol …
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Studying Ultrafast Vibrational dynamics of Intramolecular Hydrogen Bonds using Broadband Infrared Pump-Probe Spectroscopy.
The concept of hydrogen bonding has been intimately involved in the bonding and arrangement pattern of various molecular assemblies including complex protein structure. There are also indications that hydrogen bonds play an important role also in biological electron transfer across long distances. …
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Structural Determination of Copolymers from the Cross-catalyzed Reactions of Phenol-formaldehyde and Polymeric Methylenediphenyl Diisocyanate
… an enhanced reactivity that was attributed to intramolecular hydrogen bonding and a resulting resonance stabilization of the phenolic aromatic ring. ATR-FTIR spectroscopic studies generated real time structural information for model compound reactions of the cross-catalyzed system, …
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