Principles and Applications of Multidimensional NMR Spectroscopy of Solid State of Natural Isotope Abundance
AbstraktThe review is devoted to current trends in modern solid-state NMR spectroscopy, which provide detailed information about structure and segmental dynamics of various systems of natural isotope abundance. Basic experimental techniques involving magic angle spinning (MAS) and several heteronuclear and homonuclear decoupling sequences leading to suppression of chemical shift anisotropy and dipolar interactions are briefly introduced. Recent results concerning the application of 2D heteronuclear and homonuclear correlation experiments to investigation of synthetic materials (predominantly polymers) are described. The abilities of two-dimensional 1H-1H spin-exchange and 1H-13C heteronuclear correlation techniques to characterize structure of organic solids and morphology of polymer blends as well as their limitations resulting from segmental mobility and undesired coherence transfer are discussed. Possibilities to precisely measure interatomic distances and determine domain sizes in heterogeneous systems are discussed. Although most of the presented techniques were originally designed for nuclei with spin ½, application of two-dimensional single-quantum/double-quantum correlation experiment (27Al SQ/DQ MAS NMR) to increase spectral resolution of NMR spectra of quadrupolar nuclei is introduced.