Solid-state NMR spectroscopy, use

In all previous examples, diamagnetic biomolecules were studied by solid-state NMR spectroscopy using the biradical TOTAPOL as an external polarization agent. However, about 10% of biological macromolecules possess a paramagnetic (metal)... 

The problems involved in quantitative analysis using NMR spectroscopy, have been discussed by several authors and it is evident that it still causes a lot of problems as especially pointed out by Hays55 in his excellent review on the subject. Thus in liquid state NMR spectroscopy the quantitative estimation of atoms and groups involves the use of normal analytical method. In the case of solid state NMR spectroscopy, however, the application of the cross-polarization technique results in signal enhancements and allows repetition rates faster than those allowed by the carbon C-13 Tl. Therefore, the distortion of relative spectral intensities must always be considered a possibility, and hence quantitative spectra will not always be obtained. 

Neagu, C., Puskas, J.E., Singh, M.A., and Natansohn, A. Domain sizes and interface thickness determination for styrene-isobutylene block copolymer systems using solid-state NMR spectroscopy. Macromolecules, 33, 5976-5981, 2000. 

Probing Hydrogen Bonding in Solids Using Solid State NMR Spectroscopy A. E. Aliev K. D. M. Harris... 

Shi et al.71 have assigned the backbone and side-chain chemical shifts for 103 of 238 residues of proteorhodopsin using solid state NMR spectroscopy. Analysis of the chemical shifts has allowed determination of protonation states of several carboxylic acids as well as boundaries and distortions of trans-membrane a-helices and secondary structure elements in the loops. It has been shown that internal Asp227, making a part of the counterion, is ionised, while Glul42 located close to the extracellular surface is neutral. 

Solid-state NMR spectroscopy was used for studying the formation of cubic mesoporous aluminophosphate thin films and powders. The analysis of the initial gel, the as-deposited materials and the thermally-treated materials elucidated the changes in the coordination of phosphorus and aluminium atoms and thus revealed how the framework formation and condensation proceeds. The consolidation process in thin films was different than the process in powders. Most probably this could be attributed to the effect of glass substrate. 

Overall, the contributors to this volume have provided first-hand accounts of various important research topics in solid-state NMR. Being the editor, I feel very privileged to work with my very distinguished colleagues, who have been at the frontier of their fields for many years. Thanks to their painstaking efforts I am very much convinced that this volume will be a useful reference for researchers and students who are interested in the principles and applications of solid-state NMR spectroscopy. 

Lindner et al. carried out detailed studies on the use of the sol-gel procedure to obtain new materials as suitable matrices [45]. A co-condensation of Si(OR)4, Si(OR)3-spacer-Si(OR)3 and Si(OR)3-spacer-ligand resulted in new hybrid materials, the properties of which strongly depended upon the spacer and the ratio of the different components used. Most of these materials were characterised with IR, EXAFS, and EDX spectroscopy, scanning electron microscopy and solid state NMR spectroscopy. Solid state 31P NMR was used to quantify the mobility of the interphases the changes in line-... 

Crosslinked polymer networks formed from multifunctional acrylates are completely insoluble. Consequently, solid-state nuclear magnetic resonance (NMR) spectroscopy becomes an attractive method to determine the degree of crosslinking of such polymers (1-4). Solid-state NMR spectroscopy has been used to study the homopolymerization kinetics of various diacrylates and to distinguish between constrained and unconstrained, or unreacted double bonds in polymers (5,6). Solid-state NMR techniques can also be used to determine the domain sizes of different polymer phases and to determine the presence of microgels within a poly multiacrylate sample (7). The results of solid-state NMR experiments have also been correlated to dynamic mechanical analysis measurements of the glass transition (1,8,9) of various polydiacrylates. 

Solid-state NMR spectroscopy was also used to examine the post reaction behavior of pTrMPTrA samples prepared in bulk as thin films, as described in the experimental. All of the spectra in this aging study required a minimum of 720 scans on approximately 50 mg of sample with a 100 s pulse delay to achieve adequate signal/noise. Under these conditions, reliable peak areas could be obtained from the curve fits of the carbonyl region. Figure 3 depicts the evolution of the solid state spectrum of the sample stored under N2 over time and upon heating. The area of the peak at 174 ppm for the carbonyl adjacent to the reacted double bond increases as the peak at 166 ppm for pendant unsaturation decreases. The results of the aging study are given in Table I. 

We have found that combined solid-state NMR spectroscopy and DPC results can be used to calculate reaction enthalpies which are in close agreement with Moore (15). Furthermore, we find that the degree of conversion can be significantly affected by post reaction thermal processing. We conclude that the single pulse solid-state NMR spectroscopy can provide reliable, reproducible, and quantitative information about these highly crosslinked, insoluble, polymer networks. 

It follows that, as used in solid state NMR spectroscopy, 13C observation may have potential advantages in that the 13C nucleus has a wider chemical shift range than 1H, making the spectral resonances of individual molecular species more easily... 

Recently, solid state nmr spectroscopy has been used to probe hydrogen-bonded materials and first reports showed that there was a direct relationship between / o o anisotropic chemical shift as bonds become... 

Solid-state nmr spectroscopy on a single crystal of KHF2 was interpreted in terms of a centred proton with f = 113.8 pm (Pratt and Smith, 1975). The same conclusion was reached for the other alkali-metal bifluorides (Ludman et al., 1977) and the displacement of the proton from the midpoint was estimated to be less than 60 pm. This technique cannot distinguish between a single minimum and a double minimum with fast transfer. Fluorine-19 nmr spectroscopy has been used to study solutions of HFj" in formic acid, and the data have been interpreted in terms of equilibria involving F , HF, HF2 and H2F2 (Coulombeau, 1977). 

By their nature, and in contrast with microscopic and scattering techniques that are used to elucidate long-ranged structure, spectroscopic methods interrogate short-range structure such as interactions between fixed ions in side chains and counterions, main chain conformations and conformational dynamics, and the fundamental hopping events of water molecules. The most common methods involve infrared (mid-IR and to a much lesser extent near- and far-IR) and solid-state NMR spectroscopies, although other approaches, such as molecular probes, have been utilized. 

Solid state NMR spectroscopy is used to determine molecular structures by analyzing the static and dynamic features of the material. In NMR experiments, both a magnetic field and a radio frequency field are applied to a solid sample or a solution resulting in an absorption of energy, which is detected as an NMR. Spectrometers are also available for high resolution solid state NMR. Nuclei in... 

Nuclei in solid samples typically relax very efficiently and give rise to very broad spectra. NMR spectra of solid samples can only be acquired using specialised spectroscopic equipment and solid state NMR spectroscopy will not be discussed further. 

P3 The goal of the proposed research is to investigate the structural and dynamic properties of integral membrane proteins through the use of EPR spin-label spectroscopy and solid-state NMR spectroscopy. (From Lorigan, 2002)... 

Both solution-state and solid-state NMR spectroscopy are important analytical tools used to study the structure and dynamics of polymers. This analysis is often limited by peak overlap, which can prevent accurate signal assignment of the dipolar and scalar couplings used to determine structure/property relationships in polymers. Consequently, spectral editing techniques and two- or more dimensional techniques were developed to minimize the effect of spectral overlap. This section highlights only a few of the possible experiments that could be performed to determine the structure of a polymer. 

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