Nuclear Magnetic Resonance NMR Investigations

1 Local Environments in Highiy Fluorinated Silica through NMR Experiments 

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Nuclear magnetic resonance (NMR) investigations done by the laboratories of Henkel [62] showed that two regioisomers are formed. Both regioisomers... 

Several studies on nuclear magnetic resonance (NMR) investigations of derivatives belonging to this chapter have already been summarized in CHEC-II(1996) <1996CHEG-II(8)421> and, also recently, a fairly substantial amount of new experimental work has been published. 

Thorough nuclear magnetic resonance (NMR) investigations of some tetrazolo[l,5-/7]pyridazines and tetrazolo[l,5- J-pyrazine-7-oxides have been carried out by Cmoch et al. <1999MRC493, 2003MRC693>. Comparison of 13C and 1SN NMR chemical shifts of the ring atoms are shown in Table 1. 

The quarterrylene (49) and other o/igo(peri-naphthylene)s, which are large condensed PAHs with interesting fluorescence behavior, have been synthesized in an overall three-step aryl-aryl coupling sequence from suitably substituted naphthalenes. Electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) investigations indicate, that this reaction proceeds via the dianions of 47 and 48, which were oxidized with cadmium chloride to the neutral hydrocarbons. 

Detailed 2D nuclear magnetic resonance (NMR) investigations on the hydrodimers formed by 1-3 showed that all three catalyst precursors (when combined with MAO) yielded two diastereomeric hydrodimers, which were found to be the meso and racemic isomers shown in Figure 16.1a. 

X-ray and nuclear magnetic resonance (NMR) investigations indicate more complex, stoichiometry-dependent types of stmaures involving bridging alkyl groups between the two types of metal centers for aluminum, magnesium, and zinc systems as represented in Scheme 6. ... 

A net decrease in PEO crystallinity was observed with the incorporation of fillers. ° In PEO/LiTFSI complexes, an amorphous structure, stable for several months, can be obtained with the incorporation of small amounts of fillers. Using Li nuclear magnetic resonance (NMR) investigation, Dai et found that the addition of nanometric AI2O3 to PEO/Lil electrolyte suppressed the formation of crystalline phases. The ceramic fillers, because of their large surface area, may prevent local PEO organisation and significantly reduce PEO crystallisation kinetics. 

Nuclear magnetic resonance (NMR) spectroscopy is another physical technique which is especially useful for microstructure studies. Because of the sensitivity of this technique to an atom s environment in a molecule, NMR is useful for a variety of microstructural investigations We shall consider the application to copolymers now and to questions of stereoregularity in Sec. 7.11... 

Specific optical rotation values, [a], for starch pastes range from 180 to 220° (5), but for pure amylose and amylopectin fractions [a] is 200°. The stmcture of amylose has been estabUshed by use of x-ray diffraction and infrared spectroscopy (23). The latter analysis shows that the proposed stmcture (23) is consistent with the proposed ground-state conformation of the monomer D-glucopyranosyl units. Intramolecular bonding in amylose has also been investigated with nuclear magnetic resonance (nmr) spectroscopy (24). 

The spectroscopic techniques that have been most frequently used to investigate biomolecular dynamics are those that are commonly available in laboratories, such as nuclear magnetic resonance (NMR), fluorescence, and Mossbauer spectroscopy. In a later chapter the use of NMR, a powerful probe of local motions in macromolecules, is described. Here we examine scattering of X-ray and neutron radiation. Neutrons and X-rays share the property of being found in expensive sources not commonly available in the laboratory. Neutrons are produced by a nuclear reactor or spallation source. X-ray experiments are routinely performed using intense synclirotron radiation, although in favorable cases laboratory sources may also be used. 

The small amount of available crystalline abscisin II limited this investigation to the measurement and interpretation of elemental analysis, mass spectrum, and infrared, ultraviolet, and nuclear magnetic resonance (NMR) spectra (11). 

The conformation of [34-65] bacterioopsin polypeptide incorporated into perdeuterated sodium dodecyl sulfate micelles in the presence of trifluoroethanol was investigated by nuclear magnetic resonance (NMR) [184],... 

The presence of four kinds of nuclear magnetic resonance (NMR) observable nuclei ( H, uB, 13C, and 29Si) allows poly(m-carborane-siloxane) to be readily investigated using NMR spectroscopy. In addition, H spin-echo NMR relaxation techniques can provide an insight into polymer segmental chain dynamics and therefore useful information on material viscoelastic characteristics. 

Nuclear magnetic resonance (NMR) spectroscopy in pharmaceutical research has been used primarily in a classical, organic chemistry framework. Typical studies have included (1) the structure elucidation of compounds [1,2], (2) investigating chirality of drug substances [3,4], (3) the determination of cellular metabolism [5,6], and (4) protein studies [7-9], to name but a few. From the development perspective, NMR is traditionally used again for structure elucidation, but also for analytical applications [10]. In each case, solution-phase NMR has been utilized. It seems ironic that although —90% of the pharmaceutical products on the market exist in the solid form, solid state NMR is in its infancy as applied to pharmaceutical problem solving and methods development. 

The preferred conformations of methoxy groups attached to aromatic rings in the phenethylamines have recently been investigated using theoretical approaches, gas phase experimental methods, and nuclear magnetic resonance (NMR) techniques for the molecules in aqueous solution. Ab initio theoretical calculations and experimental gas phase results have indicated that when two... 

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