Solid-state nuclear magnetic resonance disorder

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]. 

Cavitands. p. 219 Clathrate Hydrates, p. 274 Disorder and Diffuse Scattering, p. 457 Hydrogen Bonding, p. 658 Hydrophobic Effects, p. 673 Isostructurality of Inclusion Compounds, p. 767 Neutron Diffraction, p. 959 Soft and Smart Materials, p. 1302 Solid-State Nuclear Magnetic Resonance Spectroscopy, p. 1307... 

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,... 

Chevallier F., Letellier M., Morcrette M., Tarascon J.M., Frackowiak E., Rouzaud J.N., Beguin F. In situ 7Li-Nuclear Magnetic Resonance Observation of Reversible Lithium Insertion into Disordered Carbons, Electrochem. Solid State Lett. 2003 6 A225-8. 

Methods used to obtain conformational information and establish secondary, tertiary, and quaternary structures involve electron microscopy, x-ray diffraction, refractive index, nuclear magnetic resonance, infrared radiation, optical rotation, and anisotropy, as well as a variety of rheological procedures and molecular weight measurements. Extrapolation of solid state conformations to likely solution conformations has also helped. The general principles of macromolecules in solution has been reviewed by Morawetz (17), and investigative methods are discussed by Bovey (18). Several workers have recently reexamined the conformations of the backbone chain of xylans (19, 20, 21). Evidence seems to favor a left-handed chain chirality with the chains entwined perhaps in a two fold screw axis. Solution conformations are more disordered than those in crystallites (22). However, even with the disorder-... 

Chevallier, F., Letellier, M., Morcrette, M., et al. (2004). In situ Li Nuclear Magnetic Resonance observation of reversible lithium insertion into disordered carbons. Electrochem. Solid State Lett., 6, A225—8. 

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. 

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