Solid-state nuclear magnetic resonance amorphous solids

Wheat starch lysophospholipid forms tiny liposomes in water that could readily be transported into the interior of a starch granule during its development. Solid-state nuclear magnetic resonance spectroscopy suggests that the phospholipids in wheat starch are predominantly complexed with amylose in an amorphous form in the granules.354-356... 

S. Kaplan, F. Jansen, M. Machonkin Characterization of amorphous carbon-hydrogen films by solid-state nuclear magnetic resonance. Appl. Phys. Lett. 47, 750 (1985)... 

Solid-state nuclear magnetic resonance (NMR) has been extensively used to assess structural properties, electronic parameters and diffusion behavior of the hydride phases of numerous metals and alloys using mostly transient NMR techniques or low-resolution spectroscopy [3]. The NMR relaxation times are extremely useful to assess various diffusion processes over very wide ranges of hydrogen mobility in crystalline and amorphous phases [3]. In addition, several borohydrides [4-6] and alanates [7-11] have also been characterized by these conventional solid-state NMR methods over the years where most attention was on rotation dynamics of the BHT, A1H4, and AlHe anions detection of order-disorder phase transitions or thermal decomposition. There has been little indication of fast long-range diffusion behavior in any complex hydride studied by NMR to date [4-11]. 

Moisture was known to increase the mobility of the surface groups of protein as measured by solid-state nuclear magnetic resonance spectroscopy The distribution of water between the protein and the excipients in a freeze-dried powder depends on the crystalline or amorphous nature of the excipients. For example, if a protein is formulated with an amorphous excipient and stored in a sealed container, water would distribute according to the water affinity of the protein and excipients.When the amorphous excipient crystallizes (e.g., because of elevated temperatures), it will expel its sorbed water, which may cause stability problems in the protein. ... 

Solid-state nuclear magnetic resonance (NMR), a canonical technique of chemistry and physics, possesses many versatile features such as, for example, elemental specificity and local structural, electronic, and motional sensitivity. In particular, NMR can characterize samples in most types of condensed matter, be it liquid or solid, single crystal or amorphous. Given adequate sensitivity it has, therefore, the unique ability of providing metal surface and adsorbate electronic and structural information on a molecular level and allows one to access motional information of adsorbate over a time range unattainable by any other single spectroscopic technique. In addition, solid-state NMR is nondestructive, technically versatile. 

Properties of Amorphous Carbon, ed. R. Silva in EMIS Datareviews Series, Vol. 29, Institution of Electrical Engineers, 2003 R 283 J.D. Carey, Solid-State Nuclear Magnetic Resonance Studies of a-C Thin Films , p. 103... 

Solid-state nuclear magnetic resonance (ssNMR) spectroscopy has emerged over the years as a powerful analytical method in solid-state chemistry, especially with the advancements in techniques that allow the acquisition of high-resolution spectra [47]. In the broadest sense, ssNMR is mostly applied in characterization of crystalline materials as a means to support PXRD structural analyses by providing information on the number of molecules in the asymmetric unit or the symmetry of the occupied positions within the unit cell. Another major field of application is the structural characterization of amorphous and disordered solids where standard X-ray diffraction-based techniques fail to give detailed structural information. When discussing ssNMR in the context of API polymorphism and synthesis of co-crystals,... 

This form is often referred to as smectic and was first mentioned in 1958 by Slichter and Mandell who observed a peculiar wide angle X-ray diffraction (WAXD) pattern in a sample melted and then rapidly quenched with dry ice. It is characterized by an order intermediate between those found in crystalline and in amorphous phases and is metastable since annealing at temperatures higher than 70°C leads to the crystallization of a-iPP. While density is low (0.88 g/cm ), infrared (IR) spectra indicate that iPP chains adopt the usual 3j helix conformation. Solid state nuclear magnetic resonance (NMR) shows a closer resemblance to p-iPP while WAXD patterns are in favor of a predominance of very local (pairs of chains) arrangements similar to those found in a-iPP. 

Several surface-sensitive techniques can provide details about bonding in amorphous materials. Such information complements structural analyses obtained by traditional bulk analytical techniques like Raman and infrared spectroscopy, solid state nuclear magnetic resonance spectroscopy, and Mossbauer spectroscopy. 

Cho, G., Yen, B.K., and Klug, C.A. Structural characterization of sputtered hydrogenated amorphous carhon films by solid state nuclear magnetic resonance. 

BustiUo, K.C., Petrich, M.A., and Reimer, J.A. Characterization of amorphous hydrogenated carbon using solid-state nuclear magnetic resonance spectroscopy. 

Gels of SPS with different solvents have been compared to clathrates. WAXD results using toluene (a good solvent for SPS) and decalin (a relatively poor solvent for SPS) show that the structure of the crystalline junctions of the gels is similar to that of the clathrate a phase. A difference can be found in the width of the (010) reflection, which is relative to the width of the (210) reflection, much broader for the gel than for the clathrate. This is caused by the difference in the mechanism involved in crystal formation in gels and clathrates. Experiments performed on quenched samples of SPS with the monomer benzyl methacrylate show that also for this gel the structure of the crystalline part is similar to that of the clathrate phase. This means that solvent is present in both the crystalline and the amorphous parts of the gel. By solid-state nuclear magnetic resonance (NMR) studies, a clear difference in the mobility of solvent molecules in the crystalline and amorphous parts of the gel has been observed [58]. 

Spectroscopic methods, such as FT-infrared (FTIR) and Raman spectroscopy detect changes in molecular vibrational characteristics in noncrystalline solid and supercooled liquid states. Various nuclear magnetic resonance (NMR) techniques and electron spin resonance (ESR) spectroscopy, however, are more commonly used, detecting transition-related changes in molecular rotation and diffusion (Champion et al. 2000). These methods have been used for studies of the amorphous state of a number of sugars in dehydrated and freeze-concentrated systems (Roudaut et al. 2004). 

Nuclear magnetic resonance (NMR)—Unlike other structural techniques, such as powder and single-crystal x-ray and neutron diffraction, which characterize the "long-range" order, giving an average view of a structure, solid-state NMR probes the local environment of a particular nucleus and, therefore, is highly suited to study amorphous or disordered materials, such as modified LDH. An extensive review of NMR studies related to both the structure and dynamics in LDH materials was reported by Rocha [11]. Herein, we concentrate on site-specific information available from the H and Al solid-state NMR. 

Nuclear magnetic resonance (NMR) is one of the major experimental tools in structural chemistry and biochemistry. The prediction of NMR shifts from ab initio calculations has been demonstrated for isolated molecules (see NMR Chemical Shift Computation Ab Initio), but the development of a practical ab initio approach for the calculation on NMR shifts in solids has been accomplished only quite recently. Based on DFT-LDA and a pseudopotential plane wave approach, these authors have presented an approach which promises to be useful in the investigation of NMR shifts in crystalline solids as well as in amorphous materials and liquids. As a demonstration of this approach, Mauri et al. have calculated the H NMR shifts of LiH and HF in the state of isolated molecules and in a crystal. In the case of LiH the results show very little change between the free molecule (a = 26.6 ppm) and the crystal (cr = 26.3 ppm). However, a significant change is found for the crystal at high pressures (65 GPa), where the chemical shift increases to 31.2 ppm. A quite different picture is obtained for the HF molecule, where the theory predicts a shift of 28.4 ppm in remarkable agreement with the experimental value of 28.4 ppm. For the HF crystal, a shift of... 

Solid state materials have been studied by nuclear magnetic resonance methods over 30 years. In 1953 Wilson and Pake ) carried out a line shape analysis of a partially crystalline polymer. They noted a spectrum consisting of superimposed broad and narrow lines which they ascribed to rigid crystalline and amorphous material respectively. More recently several books and large articles have reviewed the tremendous developments in this field, particularly including those of McBrierty and Douglas 2) and the Faraday Symposium (1978)3) —on which this introduction is largely based. 

Figure 15.9. 13C CPMAS NMR spectrum of humin extracted from a brown chernozem soil from Western Canada. The characteristic doublet in the unsubstituted aliphatic region is characteristic of methylene carbon (28-34 ppm) and shows the presence of both amorphous (soft) domains at 29 ppm and crystalline (rigid) domains at 33 ppm in soil humin. Reprinted from Simpson, M. I, and Johnson, R C. E. (2006). Identification of mobile aliphatic sorptive domains in soil humin by solid-state 13C nuclear magnetic resonance. Environ. Toxi. Chem. 25, 52-57, with permission from the Society of Environmental Toxicology and Chemistry.

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