Solid-state NMR method

Solid-state NMR methods have been much used to study the characteristics of the network chains themselves, particularly with regard to orientations [265], molecular motions [266], and their effects on the diffusion of small molecules [267], Aspects related to the structures of the networks include the degree of cross-linking [268,269], the distributions of cross-links [270] and stresses [271], and topologies [272,273]. Another example is the use of NMR to clarify some issues in the areas of aging and phase separation [274],... 

Confinement effects may also be employed to characterize the nucleation and growth of porous materials [211]. The underlying mechanisms of self-assembly and crystallization of these complex heterogeneous systems may be traced by solid state NMR methods well before their detection by diffraction methods. 

Solid-state NMR methods have been used to characterize both elemental and compound bulk semiconductors for half a century, but a significant upturn in the level of activity and the sophistication of methods and analyses is taking place, not to mention the availability of much higher magnetic fields than were available for many of the early studies. In many cases, the availability of well-defined and optically and electrically well-characterized bulk samples will prove crucial. 

Recent solid state NMR studies of liquid crystalline materials are surveyed. The review deals first with some background information in order to facilitate discussions on various NMR (13C, ll, 21 , I9F etc.) works to be followed. This includes the following spin Hamiltonians, spin relaxation theory, and a survey of recent solid state NMR methods (mainly 13C) for liquid crystals on the one hand, while on the other hand molecular ordering of mesogens and motional models for liquid crystals. NMR studies done since 1997 on both solutes and solvent molecules are discussed. For the latter, thermotropic and lyotropic liquid crystals are included with an emphasis on newly discovered liquid crystalline materials. For the solute studies, both small molecules and weakly ordered biomolecules are briefly surveyed. 

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... 

Solid-State NMR Method in Catalysis by Surfiice Organometallics... 

McDermott et al used rotational resonance, a then newly developed solid-state NMR method, for structural studies of an inhibited complex formed by reaction of D-alanine D-alanine ligase, ATP, and the aminoalkyl dipeptide analogue. The measured NMR coupling properties indicate that the two species are bridged in a P—O—P linkage, with a P—P through-space distance of 2.7 0.2 A. This work unambiguously demonstrated that the inactivation mechanism involves phosphorylation of enzyme-bound inhibitor by ATP to form a phos-phoryl-phosphinate adduct. ... 

Grant et al. described an investigation of the ternary complex of ATP and bis(2-pyridyl)amine (MgATP/BPA), using advanced solid-state NMR methods such as Mg REDOR and Mg MQMAS in Mg-isotopically enriched samples. In the 3QMAS spectrum, the authors detected the presence of two Mg sites with close Mg quadrupole parameters. With help of a REDOR experiment, the assignment of these two sets of parameters to Mg ions either coordinated to water molecules or to phosphate oxygen donors was then possible. 

Aluminum forms mixed oxides with many other metals which either replace Al3+ in octahedral positions or occupy tetrahedral sites. The spinel structure of MgAl204, an important prototype, has been investigated by photoelectron spectroscopy.122 Vibrational and solid state NMR methods are also useful for studying aluminate structures.12 125... 

Abstract Membrane proteins represent an important and challenging frontier in structural biology they mediate fundamental and medically important processes but are challenging targets for structure/ function studies. Magic angle spinning solid-state NMR methods for structure determination of proteins have developed rapidly in... 

The results indicate that the proton is shared between the nitrogen and oxygen atoms, with a preference for O-H rather than N-H character. Further advanced solid state NMR methods were used to measure the N -H distance via the N - - H dipolar coupling. 

Advances in NMR spectrometer and probe technology and in solid-state NMR methods, along with development of new pulse sequences have opened up the biomolecular NMR field to the study of membrane-bound proteins and large molecular weight (MW > 50 kDa) systems. In addition, studies of low-sensitivity nuclei are expected to gain in popularity as the appropriate technical and experimental expertise is developed and refined. Another important area concerns developments in protein engineering that allow preparation of biomolecules isotopically labeled either uniformly or at particular sites. The rapid and continuing development of these... 

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]. 

Progress in the field of chemical and biological sciences is continually impacted by the development of novel methods of structural analysis. Sheiko and Moller review a field that started to develop only in the past several years, i.e., visualization of biological and synthetic macromolecules including individual macromolecules and their motion on surfaces with the aid of scanning force microscopy (SFM). Brown and Spiess analyze the most recent advances in solid-state NMR methods for the elucidation of the struc-... 

Advanced Solid-State NMR Methods for the Elucidation of Structure and Dynamics of Molecular, Macromolecular, and Supramolecular Systems... 

As indicated by the opening paragraphs, the emphasis of this review is on advanced solid-state NMR experiments suitable for providing insight into the mechanisms of self-assembly which are of much relevance in modern polymer science. As such, we restrict our attention to the spin /= 1/2 nuclei found in organic solids, in particular, H and 13C, and focus on recently developed, i.e., within the last 10 years, solid-state NMR methods that probe the structural and dynamic information inherent to the dipolar coupling. Importantly, we will show that H NMR of rigid solids is now feasible. 

The proven power of the single-crystal diffraction techniques does not, however, make solid-state NMR irrelevant. In materials science, most samples do not possess long-range translational order, and it is not possible to prepare single crystals. Such samples are, however, usually well-ordered on a local scale. The solid-state NMR methods introduced in the previous... 

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