Global ETD Search
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 276 for “"Hydrogen bonds"”.
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Palladium catalyzed carbon-carbon bond formation at carbon-hydrogen bonds
The biaryl core has been identified by medicinal chemists as a privileged structure in pharmaceutical compounds as it is found in 4.3% of all drugs. For over a century, synthetic chemists have sought new methods for their preparation. Breakthroughs in synthetic catalytic methodology over the past …
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Heterocyclic Building Blocks for Supramolecular Construction Using Multiple Hydrogen Bonds
Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs
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Vibrational Energies of the Hydrogen Bonds of H₃O₂⁻ and H₅O₂⁺
… of the symmetric and asymmetric stretches of the hydrogen bonds of the molecules H_3O_2^- and H_5O_2^+ by applying an improvement to the standard time-independent Born-Oppenheimer approximation. These two molecules are symmetric around a central hydrogen which participates in hydrogen bonding. …
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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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Substituent Effects: A Computational Study on Stabilities of Cumulenes and Low Barrier Hydrogen Bonds
… been used to study the energetics of low-barrier hydrogen bond (LBHB) systems. Using substituted formic acid-formate anion complexes as model LBHB systems, hydrogen bond strength is correlated to the pKa mismatch between the hydrogen bond donor and the hydrogen bond acceptor. LBHB model systems …
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A trajectory-based approach to modeling nonlinear infrared spectra : interrogating strong hydrogen bonds and proton transfer
… systems, focusing on applications to strongly hydrogen bonded complexes. To overcome the limitations inherent in common analytical models, I construct full time trajectories for spectroscopic variables, here the vibrational frequencies and transition dipole moments, and use these as inputs to …
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Temperature Programmed Desorption and Infrared Spectroscopic Studies of Interfacial Hydrogen Bonds for Small Molecules Adsorbed on Silica and Within Metal Organic Frameworks
Hydrogen bonds are arguably the most important reversible intermolecular forces. However, surprisingly few studies of their fundamental nature at the gas-surface interface have been performed. Our research investigated sulfur mustard (HD) adsorption by characterizing interfacial hydrogen bonding …
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Accurate charge densities of amino acids and peptides by the Maximum Entropy Method
… Maximum Entropy Method (MEM) to study chemical bonds. The MEM model-independently determines the most probable electron density, which simultaneously maximizes the information entropy and fits the X-ray diffraction data. The quality of the MEM densities is enhanced by several extensions to the …
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Studies of metaphosphate acids and metaphosphate anhydrides in aprotic media
… of metaphosphate acids are dictated by strong hydrogen bonding interactions. As a consequence of anti-cooperative effect, intramolecular hydrogen bonds are preferred at low degrees of protonation, and intermolecular hydrogen bonds are preferred at high degrees of protonation, resulting in …
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The Role of CH–π Interactions in Protein-Carbohydrate Binding
… by several types of non-covalent interactions: hydrogen bonding, metal ion coordination, and the less well-understood CH–π interactions. CH–π interactions are pervasive in protein-carbohydrate binding sites and have emerged as critical drivers of protein–carbohydrate recognition; however, the …
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Hydrogen transfer in hydrogen bonded solid state materials
The investigation of strongly hydrogen bonded solid state materials and the hydrogen transfer processes therein are the subject of the present work. Strong hydrogen bonds are found whenever the hydrogen bonded species compete for the hydrogen atom, and are thereby on the verge of showing hydrogen …
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Nature's way: the effects of hydrogen bond networks on acidities, catalysis, and molecular recognition
Hydrogen bond networks play a critical role in many biological processes. Herein, hydrogen bond arrays are studied and exploited. Their strengths are measured in compounds with multiple hydrogen bonds to better understand enzymatic reactions. Anion recognition abilities of synthetic hydrogen bonded …
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2,4,6-Tris(isopropylamino)-1,3,5-trinitrobenzene : Probing the Impact of Crystal Packing Forces in the Dimorphs and the Cocrystals–Experimental and Theoretical Study
… molecular structures after the correction of the hydrogen atomic positions, using the Density Functional Theory (DFT) electronic structure program DMOL3 (2.2), with DNP basis set and GGA-BLYP functional. The molecular structures with the calculated charges then have been used to calculate: the …
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Thermodynamics of Buried Water in Protein Cavities and Revised Algorithms for Introducing Polarizability to Molecular Dynamics Simulations
… one which is polar, forming four water-protein hydrogen bonds, and two which are more hydrophobic, only forming one or two water-protein hydrogen bonds. The calculations give very different free energies for the different cavities, with only the polar BPTI cavity predicted to be hydrated. The …
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NOVEL ETHYLENE-BRIDGED HEXADENTATE BIS(AMIDINES), BIS(AMIDINATES), AND MULTINUCLEAR COINAGE METAL BIS(AMIDINE) COMPLEXES
… also exhibit unique NH···Cl–M–N' hydrogen bridges that are generated by formal insertion of the M–Cl fragments into the intramolecular NH···N' hydrogen bonds of <strong>L</strong><sup>4</sup>H<sub>2</sub>. These hydrogen bonds can be observed in the solid state and <sup>1</sup>H …
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Single-conformation spectroscopy of hydrogen bonding networks: Solvation, synthetic foldamers, and neurodegenerative diseases
<p>The hydrogen bond is one of the most important interactions in natural processes ranging from protein folding to chemical reactions. Two complementary methodologies are applied to understanding this important interaction: top-down and bottom-up. Top-down methods use large molecules, such as …
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Studies of liquid phase intermolecular interactions utilizing ¹H and ¹³C dynamic nuclear polarization and nuclear magnetic resonance techniques
… different acidities of the respective carbon-hydrogen bonds. The ¹³C DNP results demonstrated that the scalar dominated enhancement is sensitive to the acidity of carbon-hydrogen bonds as well as to the correlation times of the sample molecules. A hydrogen bonding spin polarization model is …
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Investigation on the Mechanisms of Elastomechanical Behavior of Resilin
… modulus include the formation of intramolecular hydrogen bonds, altered structural organization, or passing through a glass transition, all of which have been reported in the literature for polymeric materials. Results show that in nature, resilin operates at a much lower frequency than this …
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Advances in the theoretical determination of molecular structure with applications to anion photoelectron spectroscopy
… to systems with intra and intermolecular hydrogen bonds. I have developed and demonstrated usefulness of Potential Energy Surface Scanning Tool (PESST) by performing a systematic search for the most stable structures of neutral and anionic phenylalanine and tyrosine molecules using …
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Deuterium and Nitrogen-14 Nuclear Quadrupole Double Resonance Studies of Hydrogen Bonding
… accompanies formation of N-H...O and N-H...N hydrogen bonds in the solid state was investigated via deuterium and nitrogen-14 nuclear quadrupole resonance (nqr) spectroscopy. The experimental techniques of double resonance with level crossing and double resonance with continuous coupling were …
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