Resolution Solid State NMR Research Articles

The structure of ( iBu 3Sn) 2CO 3 and (Me 3Sn) 2CO 3 in solution and in the solid state studied by 13C/ 119 Sn NMR spectros

The structures of two bis(triorganotin) carbonates (R 3Sn) 2CO 3, with R  Me ( 1a) or iBu ( 1b), have been determined by low temperature single crystal X-ray diffraction studies. The crystal structure of 1a (previously determined at room temperature) has been redetermined at 200 K, at which the structure of 1b has also been determined. Both compounds have similar polymeric structures; trigonal-planar R 3Sn moieties are axially bridged by bidentate R 3Sn-O-CO 2 units to trigonal-pyramidal R 3Sn moieties in such a way that helices parallel to the crystallographic c-axes are formed. There are differences in the number of the structural units (R 3Sn tpy(R 3Sn tpl)CO 3 needed for a complete screw thread, namely, two for 1a and four for 1b. 13C and 119Sn high resolution solid-state NMR spectroscopy are consistent with the structural findings but also the existence of dynamic processes (on the NMR time scale) for solid 1a at room temperature. Structural differences between the solid state and solution can be rationalised by comparison of solid and solution state NMR spectroscopy.

The Structure and Thermal Transformations of Allophanes Studied by 29Si and 27Al High Resolution Solid-State NMR

Examination of two volcanic and two precipitated allophanes by solid-state NMR, thermal analysis and X-ray powder diffraction shows three of the samples to contain structural features similar to both tubular imogolite and defect layer-lattice aluminosilicates such as kaolinite. The fourth allophane, a precipitated sample from New Zealand, had no imogolite-like features and contained tetrahedral as well as octahedral aluminum. The imogolite-like units in allophane are less stable thermally than tubular imogolite. The NMR spectra and their changes on heating can be accounted for by a structural model in which a two-sheet, kaolinite-like structure containing defects (holes in the tetrahedral sheet) is curved into a sphere in which imogolite-like orthosilicate units are anchored into the octahedral sheet and fit into the tetrahedral defects. Computer simulation shows that the model is crystallographically sound, and accounts for all the known facts, including the spherical morphology, the solid-state NMR spectra and the thermal dehydroxylation behavior of all except the New Zealand allophane, which is of a different structural type.

High resolution solid-state NMR spectra of leucine: a re-examination

In the CP-MAS 13C NMR spectrum of polycrystalline L-leucine, the splitting of the resonance from the β-carbon can be assigned to site differences in the P21 unit cell, and not to long-range residual dipolar coupling between 14N and 13C.

ChemInform Abstract: The Study of Hydrogen‐Bonded Structures Using High Resolution Solid‐State NMR

ChemInformVolume 19, Issue 5 Reviews ChemInform Abstract: The Study of Hydrogen-Bonded Structures Using High Resolution Solid-State NMR M. C. ETTER, Univ. Minn., Minneapolis, MN 55455, USASearch for more papers by this authorR. C. HOYE, Univ. Minn., Minneapolis, MN 55455, USASearch for more papers by this author M. C. ETTER, Univ. Minn., Minneapolis, MN 55455, USASearch for more papers by this authorR. C. HOYE, Univ. Minn., Minneapolis, MN 55455, USASearch for more papers by this author First published: February 2, 1988 https://doi.org/10.1002/chin.198805397Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume19, Issue5February 2, 1988 RelatedInformation

Biological Applications of High Resolution Solid-state NMR Spectroscopy

Abstract During the last 25 years, high resolution NMR has become one of the most powerful tools available for the elucidation of molecular structure and dynamics. Although the technique has been widely used for investigating samples in the liquid (solution) state, recent developments enable one to study solids as well. Unlike X-ray and neutron diffraction methods which are used so far mainly for solid samples, NMR spectroscopy has emerged to be powerful in studying both solids and liquids. The resolution achievable by the recently developed solid-state NMR techniques makes it possible to compare structures in two different states based on the results obtained by the same technique. Such comparisons are particularly relevant in the case of biologically important molecules like proteins, nucleic acids, and membrane components whose high molecular weights and polymeric nature dictate certain behaviors which are adequately understood only if they are studied in both solution and solid states. The technique of solid-state NMR spectroscopy therefore bridges the information gap between the conventional solution (NMR, ESR, and optical spectroscopy) and solid-state methods (X-ray and neutron diffraction).

Application of High Resolution Solid-State NMR to Surface Science

The principles and methods of high resolution solid-state NMR spectroscopy are explained briefly, followed by a review of recent reports especially on surface science studied by the technique. Two methods are used to obtain high resdution spectra, depending on the magnitude of homonuclear dipolar broadening. In the rare spin system, e.g., 13C, 29Si, and 15N, the line broadening is mostly due to heteronuclear dipolar coupling and chemical shift anisotropy, The techniques of magic angle spinning of the sample, dipolar decoupling, and cross polarization are effective to obtain high resolution spectra. As for abundant spins such as 1H, homonuclear dipolar broadening is usually dominant, which is suppressed by the multiple pulse technique. Structures and dynamics of surface species have been investigated by measuring high resolution spectra of 13C, 29Si, 1H, 31P, and 19F nuclei; usefulness of the technique is discussed.