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Updated: Jul 1, 2026

Preparation of Fungal and Plant Materials for Structural Elucidation Using Dynamic Nuclear Polarization Solid-State NMR
Published on: February 12, 2019
Stretched poly(dimethylsiloxane) gels as NMR alignment media for apolar and weakly polar organic solvents: an ideal
J Christoph Freudenberger1, Peter Spiteller, Reinhard Bauer
1Lehrstuhl für Organische Chemie II, Department für Chemie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
Abstract:
The measurement of residual dipolar couplings (RDCs), meanwhile a standard method for obtaining structural information in biomolecular NMR, requires partial alignment of the sample. Special demands on alignment media so far limit the applicability of this approach to small molecules in organic solvents. Major limitations are the free scalability of alignment and the suppression of residual signals of the alignment medium to allow effective measurement of low-concentration samples. Here, we present stretched poly(dimethylsiloxane) (PDMS) cross-linked by beta-rays as an alignment medium with no visible impurities in 1H NMR spectra but a single signal at approximately 0.1 ppm that can easily be removed by slightly modified water suppression methods. Besides the free scalability, its applicability to the measurement of RDCs in small molecules at low concentration is demonstrated on a approximately 12 mM sample of spiroindene. The induced alignment tensor in this case can be predicted reasonably well by a simplified model on the basis of steric interactions only.
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