Nuclear magnetic resonance using

Purification and characterization The crude NHS esters were recrystallized to a constant melting from either chloroform-hexane or chloroform-acetone mixed solvents. Product purity was confirmed by proton nuclear magnetic resonance using a GE QE 300 spectrometer. 

M. Bjerring, J. T. Rasmussen, R. S. Krogshave and N. C. Nielsen, Heteronuclear coherence transfer in solid-state nuclear magnetic resonance using a 7-encoded transferred echo experiment. J. Chem. Phys., 2003, 119, 8916-8926. 

J.R. Knowles enquiring as to needs for costly equipment in chemistry. In turn Knowles put the question to his college colleague, R.J.P. Williams, who had been working for some three years on protein nuclear magnetic resonance using the somewhat unsatisfactory Varian 220 MHz NMR carrier wave spectrometer (not a Fourier transform instrument) based, very inconveniently, for a while at Harwell and then at ICI near Runcorn. (This work developed... 

Some of the most successful methods of nuclear magnetic resonance used in the study of disordered porous media have been reviewed and their applications to the measurement of pore size distribution, diffusion coefficients and permeability have been presented. This is the case of nuclear relaxation and pulsed field gradient method of a specific imbibed solvent in various fully or partially saturated organic or inorganic porous media. The cases of narrow and large distributions of pores have been... 

Free-standing films of poly(l,6-heptadiyne) were indeed prepared using a number of homogeneous Zieglerjgatta catalysts. Inasmuch as the details are reported elsewhere, only a synopsis of the results will be presented here. Spectroscopic studies (infrared, nuclear magnetic resonance) using model monomers and the pol3nner film prepared from 1,6- heptadiyne-1,7-d supported... 

Chapter 1 presents the CO2 molecule and gives fundamental information for understanding the chemistry of the heterocumulene. It also discusses the excited states of CO2 and its radical anion and radical cation. Such species are often encountered in other chapters. The spectroscopic techniques (infrared, ultraviolet, nuclear magnetic resonance) used for collecting information about the state of the... 

R. Tycko, Remote sensing of sample temperatures in nuclear magnetic resonance using photoluminescence of semiconductor quantum dots, J. Magn. Reson. 244 (2014) 64—67. 

Two EVA materials with distinct vinyl acetate ratios are studied by nuclear magnetic resonance using solution and solid techniques. These studies are made in order to obtain a... 

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. 

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). 

Of spectroscopic teclmiques, nuclear magnetic resonance (NMR) has been most widely used to measure orientational ordering in liquid crystals [M, 57 and ]. Most commonly, changes of line splittings in the spectra of... 

Because this problem is complex several avenues of attack have been devised in the last fifteen years. A combination of experimental developments (protein engineering, advances in x-ray and nuclear magnetic resonance (NMR), various time-resolved spectroscopies, single molecule manipulation methods) and theoretical approaches (use of statistical mechanics, different computational strategies, use of simple models) [5, 6 and 7] has led to a greater understanding of how polypeptide chains reach the native confonnation. 

The section on Spectroscopy has been retained but with some revisions and expansion. The section includes ultraviolet-visible spectroscopy, fluorescence, infrared and Raman spectroscopy, and X-ray spectrometry. Detection limits are listed for the elements when using flame emission, flame atomic absorption, electrothermal atomic absorption, argon induction coupled plasma, and flame atomic fluorescence. Nuclear magnetic resonance embraces tables for the nuclear properties of the elements, proton chemical shifts and coupling constants, and similar material for carbon-13, boron-11, nitrogen-15, fluorine-19, silicon-19, and phosphoms-31. 

For both copolymers and stereoregular polymers, experimental methods for characterizing the products often involve spectroscopy. We shall see that nuclear magnetic resonance (NMR) spectra are particularly well suited for the study of tacticity. This method is also used for the analysis of copolymers. 

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... 

Figure 7.10 Nuclear magnetic resonance spectra of three poly(methyl methacrylate samples. Curves are labeled according to the preominant tacticity of samples. [From D. W. McCall and W. P. Slichter, in Newer Methods of Polymer Characterization, B. Ke (Ed.), Interscience, New York, 1964, used with permission.]...

Proton chemical shift data from nuclear magnetic resonance has historically not been very informative because the methylene groups in the hydrocarbon chain are not easily differentiated. However, this can be turned to advantage if a polar group is present on the side chain causing the shift of adjacent hydrogens downfteld. High resolution C-nmr has been able to determine position and stereochemistry of double bonds in the fatty acid chain (62). Broad band nmr has also been shown useful for determination of soHd fat content. 

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