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Showing 1 to 20 of 302 for “"Hydrogen bond"”.
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The Hydrogen Bond
Not Available
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The hydrogen bond strength of trifluoroacetic acid.
Thesis (M.A.)--Boston University This item was digitized by the Internet Archive.
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Carbon−Hydrogen Bond Functionalization using Removable Monodentate Directing Groups
… for copper-promoted C−H/N−H coupling of sp2 C−H bonds with pyrazoles, imidazoles, and sulfonamides. Reactions proceed in fluorinated alcohol solvents at elevated temperatures and require use of 1.3−3 equiv of copper(II) acetate. This appears to be the first method for copper-promoted C−H/N−H …
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Spectroscopic investigations of hydrogen bond dynamics in liquid water
… of liquid water are due to the strong influence hydrogen bonds have on its microscopic dynamics. However, because of the fast timescales involved, there are relatively few experimental techniques capable of directly probing rearrangements of water's hydrogen bonded network. In this thesis, I …
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Meeting the challenges: carbon-hydrogen bond activation and cancer treatment
… in oxidative addition mediated C-C, and C-O bond formation processes as well as in C-Cl bond forming reactions via a reductive elimination process. Bis-NHC-Pd(II) complexes have been reported as effective catalysts to mediate direct conversion of methane into methanol. However, a H-D exchange …
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Hydrogen Bond Template-Directed Synthesis of Recognition-Encoded Melamine Oligomers
… was investigated that uses noncovalent H-bonding interactions between 4-nitrophenols and phosphine oxides as the base-pairing chemistry for the template-directed synthesis of recognition-encoded melamine oligomers (REMO). A copper-catalysed alkyne-azide cycloaddition (CuAAC) reaction …
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Hydrogen bond mediated self-assembly: Solid state structures and synthesis of building blocks
… expanded through ethanol bridging of some of the hydrogen bonded carboxylic acid dimers. The expanded chicken wire networks of the structure do not interpenetrate. The Cambridge Crystallographic Data File (CCDF) was searched to determine the ratio of hydroxy bridge carboxylic acids to standard …
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Main Group Hydrogen-Bond Donors and Pyridyl Ligands for Supramolecular and Coordination Chemistry
… of a range of non-carbon frameworks based on P-N bonds. In the first chapter we develop strategies for enhancing the anion binding properties of phosphazanes of the type [(RNH)(E)P(µ-NtBu)]2 (E = O, S, Se) which are bench stable, H-bond receptors that can be regarded as inorganic analogues of …
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Hydrogen bond reorganization and vibrational relaxation in water studied with ultrafast infrared spectroscopy
Water consists of an extended hydrogen bond network that is constantly evolving. More than just a description of the time averaged structure is necessary to understand any process that occurs in water. In this thesis we study the dynamic regime, which involves fluctuations and rearrangements that …
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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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Studies of carbon-hydrogen and silicon-hydrogen bond activation by early transition metal complexes
Compounds that contain early transition metals particularly titanium, vanadium, and chromium, are used as catalysts for olefin polymerization in the Ziegler-Natta and Phillips processes. The key intermediates in these catalysts are thought to be six-coordinate metal alkyl/olefin complexes. The …
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Hydrogen bond rearrangements and the motion of charge defects in water viewed using multidimensional ultrafast infrared spectroscopy
… structured due to its ability to form up to four hydrogen bonds to its nearest neighbors, resulting in a tetrahedral network of molecules. However, this network is highly dynamic, exhibiting fluctuations and rearrangements that take place on femtosecond to picosecond time scales. The transport of …
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Part I: Self-Assembling Dendrimers Using the Dda-Aad Hydrogen Bonding Motif. Part II: Supramolecular Discotic Liquid Crystals Through Hydrogen Bond Mediated Self-Assembly
… 1H NMR, SEC and DLS indicate the formation of a hydrogen bonded cyclic hexamer in apolar solvents. The studies by differential scanning calorimetry (DSC), polarized light microscopy (PLM) and X-ray diffraction (XRD) indicate that the hexameric disks can stack in bulk to form thermotropic columnar …
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Part I: Rapid Synthesis of Dendrimers by an Orthogonal Coupling Strategy. Part II: Design, Synthesis, and Characterization of Hydrogen-Bond Mediated Self-Assembling Dendrimers
Part I. Layered dendrimers were rapidly synthesized using an orthogonal coupling strategy. Fourth generation dendron 71 was prepared in four steps by sequential use of two AB$\sb2$ building blocks 66 and 67 under Mitsunobu esterification and Sonogashira coupling conditions. Further accelerated …
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Artificial Transmembrane Signalling and Cooperativity in H-Bonded Networks
… signalling, and a second on cooperativity in hydrogen bonded networks. Cells rely on complex signal cascades where proteins are responsible for the transmission and amplification of chemical signals across membranes. While numerous examples of biomimetic synthetic transport systems are …
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Characterization of structural changes in thermally enhanced Kevlar-29® Fiber
… fibers. A novel theory was set forth that hydrogen bond disruption and concurrent misorientation of crystallites may account for the observed augmentation of compressive properties. To examine the said theory, virgin Kevlar-29® fibers were characterized by Thermogravimetric analysis (TGA) …
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An investigation of hydrogen bonded molecular systems using X-ray and neutron diffraction
… project have been investigations of a variety of hydrogen bonding systems for unusual behaviour such as disordered or migrating hydrogens/protons with both single crystal X-ray and neutron diffraction, crystallisation of a large number of molecular complexes of the chloranilic acid molecule, and …
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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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