High Magnetic Field for Enhanced Proton Resolution in High-Speed CP/MAS Heteronuclear1H–13C Dipolar-Correlation Spectroscopy

✍ Scribed by B.-J. van Rossum; G.J. Boender; H.J.M. de Groot

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 88 KB
• Volume: 120
• Category: Article
• ISSN: 1064-1858
• DOI: 10.1006/jmra.1996.0126

✦ Synopsis

ple-pulse sequences for high-resolution solid-state NMR It is generally accepted that heteronuclear-correlation spectroscopy of biological systems is quite impractical, if spectroscopy in solids requires the application of multiplenot entirely impossible. pulse techniques to achieve sufficient line narrowing in the In the description of the NMR response of strongly dipolar proton dimension. We now demonstrate that increasing the coupled protons in solids, the relatively small 1 H chemicalmagnetic field strength improves the resolution dramatically, shift dispersion is usually neglected. This is definitely correct to such an extent that 1 H-13 C correlations and proton shifts at lower fields, and for moderately high spinning speeds. In can be directly obtained from 2-D spectra collected without the strong dipolar limit, the proton levels are nearly degenerany homonuclear decoupling scheme during t 1 evolution.

ate, and the T 2 -type relaxation responsible for the large pro-Recently, it has been shown that dipolar-correlation specton linewidth easily proceeds throughout the rigid dipolar troscopy is an indispensable tool for the assignment of resolattice. It is obvious that this approximation must break down nances and improvement of resolution in modern multidiwhen the magnetic field is sufficiently strong. It has been mensional high-resolution solid-state NMR (1, 2). For inproposed that the dipolar interactions are effectively trunstance, structure refinement of large solid-type biological cated by the chemical shift in high fields, yielding narrower preparations using 2-D homonuclear 13 C dipolar-correlation 59, 3740 (1973).