Structure, nuclear magnetic resonance

While XAS techniques focus on direct characterizations of the host electrode structure, nuclear magnetic resonance (NMR) spectroscopy is used to probe local chemical environments via the interactions of insertion cations that are NMR-active nuclei, for example lithium-6 or -7, within the insertion electrode. As with XAS, NMR techniques are element specific (and nuclear specific) and do not require any long-range structural order in the host material for analysis. Solid-state NMR methods are now routinely employed to characterize the various chemical components of Li ion batteries metal oxide cathodes, Li ion-conducting electrolytes, and carbonaceous anodes.Coupled to controlled electrochemical in-sertion/deinsertion of the NMR-active cations, the... 

Spectroscopic techniques, in general, are very well suited for investigation into molecular aspects such as local molecular arrangements, molecular dynamics, and molecular interactions. However, for many microemulsions, in particular those that simultaneously contain large amounts of water and oil, these aspects are rather uninteresting. Local molecular dynamics are determined by short-range interactions and are essentially independent of the self-assembly structure. Nuclear magnetic resonance (NMR) is, however, particular as a spectroscopic technique in that it can also provide information on other central matters such as phase behavior and microstructure. In particular, NMR self-diffusion and, to some... 

Glycocin F, secreted by Lactobacillus plantarum KW30, was characterized and led to the identification of an unexpected N-acetylglucosamine bound to a Cysteine by a thioglycosidic linkage. Further studies by structural nuclear magnetic resonance confirmed the presence of two N-acetylglucosamine moieties, one attached to a Serine o g gen atom, the second to a Cysteine sulfur atom. ... 

Among the multiple spectroscopic techniques that can provide information about the catalytic active sites under reaction conditions (Raman, IR, UV-vis, X-ray absorption (EXAFS (extended X-ray absorption fine structure)/XANES (X-ray absorption near edge structures)), nuclear magnetic resonance (NMR), electron sprin resonance (ESR), etc.), Raman spectroscopy is the technique of choice because of... 

Physical properties Proof of structure Nuclear magnetic resonance (NMR) Mass Spectrometry (MS and MS/MS) Fourier transform infrared (FTIR) UV spectroscopy Crystallinity—isoforms Combustion analysis... 

Bioenergetics Hydrogen Bond Macro-molecules, Structure Membrane Structure Nuclear Magnetic Resonance (NMR) Protein Folding Protein Synthesis X-Ray Analysis... 

One has seen that the number of individual components in a hydrocarbon cut increases rapidly with its boiling point. It is thereby out of the question to resolve such a cut to its individual components instead of the analysis by family given by mass spectrometry, one may prefer a distribution by type of carbon. This can be done by infrared absorption spectrometry which also has other applications in the petroleum industry. Another distribution is possible which describes a cut in tei ns of a set of structural patterns using nuclear magnetic resonance of hydrogen (or carbon) this can thus describe the average molecule in the fraction under study. 

Venanzi T J 1982 Nuclear magnetic resonance coupling constants and electronic structure in molecules J. Chem. Educ. 59 144-8... 

For bulk structural detemiination (see chapter B 1.9). the main teclmique used has been x-ray diffraction (XRD). Several other teclmiques are also available for more specialized applications, including electron diffraction (ED) for thin film structures and gas-phase molecules neutron diffraction (ND) and nuclear magnetic resonance (NMR) for magnetic studies (see chapter B1.12 and chapter B1.13) x-ray absorption fine structure (XAFS) for local structures in small or unstable samples and other spectroscopies to examine local structures in molecules. Electron microscopy also plays an important role, primarily tlirough unaging (see chapter B1.17). 

Specinfo, from Chemical Concepts, is a factual database information system for spectroscopic data with more than 660000 digital spectra of 150000 associated structures [24], The database covers nuclear magnetic resonance spectra ( H-, C-, N-, O-, F-, P-NMR), infrared spectra (IR), and mass spectra (MS). In addition, experimental conditions (instrument, solvent, temperature), coupling constants, relaxation time, and bibliographic data are included. The data is cross-linked to CAS Registry, Beilstein, and NUMERIGUIDE. 

Nuclear magnetic resonance (NMR) spectroscopy is a valuable technique for obtaining chemical information. This is because the spectra are very sensitive to changes in the molecular structure. This same sensitivity makes NMR a difficult case for molecular modeling. 

Present day techniques for structure determination in carbohydrate chemistry are sub stantially the same as those for any other type of compound The full range of modern instrumental methods including mass spectrometry and infrared and nuclear magnetic resonance spectroscopy is brought to bear on the problem If the unknown substance is crystalline X ray diffraction can provide precise structural information that m the best cases IS equivalent to taking a three dimensional photograph of the molecule... 

Nuclear magnetic resonance (NMR) spectroscopy (Section 13 3) A method for structure determination based on the effect of molecular environment on the energy required to promote a given nucleus from a lower energy spin state to a higher energy state... 

TF Flavel. An evaluation of computational strategies for use m the determination of protein structure from distance constraints obtained by nuclear magnetic resonance. Prog Biophys Mol Biol 56 43, 1991. 

GM Clore, MA Robien, AM Gronenborn. Exploring the limits of precision and accuracy of protein structures determined by nuclear magnetic resonance spectroscopy. J Mol Biol 231 82-102, 1993. 

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