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A comparison of NMR distance determinations in the solid state by cross polarization, REDOR, and TEDOR techniques

TitleA comparison of NMR distance determinations in the solid state by cross polarization, REDOR, and TEDOR techniques
Publication TypeJournal Article
Year of Publication1999
AuthorsFyfe, CA, Lewis, AR, Chezeau, JM
JournalCanadian Journal of Chemistry-Revue Canadienne De Chimie
Volume77
Pagination1984-1993
Date PublishedNov
Type of ArticleArticle
ISBN Number0008-4042
KeywordsANGLE-SPINNING NMR, cross polarization (CP), DISTANCE, distances F-19-Si-29, HELICAL PEPTIDE, HETERONUCLEAR DIPOLAR, interactions, INTERATOMIC, LOCK, NMR distance measurements, NUCLEAR-MAGNETIC-RESONANCE, octadecasil, PROTON-ENHANCED NMR, REDOR, ROTATIONAL-ECHO, SEQUENCES, SPIN-1/2 NUCLEI, TEDOR, TRANSIENT OSCILLATIONS
Abstract

Solid-state NMR distance determinations using Hartmann-Hahn cross polarization between spin-1/2 nuclei (F-19/Si-29) are reported. F-19 –> Si-29 polarization transfer for the T-1 silicon site in the clathrasil octadecasil shows an oscillatory behaviour as a function of the contact time. These oscillations were observed for non-spinning powder samples and also for different spinning speeds at the various MAS sideband matching conditions. Three analytical functions that allow efficient nonlinear least-square regression analyses of the experimental data to determine the internuclear distances for non-spinning powder samples as well as at the +/-1 and +/-2 MAS sideband matching conditions are reported. Using these functions, a F-19-Si-29 distance of 2.53 +/- 0.04 Angstrom was determined for the T-1 silicon in octadecasil from fitting of the oscillatory behaviour. This distance is in good agreement with that known from the X-ray structure and the previous F-19/Si-29 REDOR and TEDOR distance measurements. The advantages and limits of the different dipolar-based NMR techniques for heteronuclear distance determinations are examined and discussed.

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