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Two-Dimensional Dynamic-Director 13C NMR of Liquid Crystals

✍ Scribed by Dan McElheny; Min Zhou; Lucio Frydman

Publisher
Elsevier Science
Year
2001
Tongue
English
Weight
107 KB
Volume
148
Category
Article
ISSN
1090-7807

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✦ Synopsis

A novel nuclear magnetic resonance (NMR) experiment for facilitating the resolution and assignment of liquid crystalline 13 C NMR spectra is described. The method involves the motor-driven reorientation of the liquid crystalline director, in synchrony with the acquisition of a 2D chemical shift correlation spectrum. By monitoring in this fashion the 13 C NMR evolution of spins in the liquid crystal at two different director orientations with respect to the magnetic field, the method distinguishes anisotropic from isotropic displacements and can be utilized for assigning the resonances and estimating local degrees of order. Of various potential pairs of angles suitable for such a correlation, the (0Β°, 90Β°) choice was found to be most convenient, as it avoids line broadening complications that may otherwise originate from heterogeneities of the oriented phase. The technique thus derived was employed in the analysis of a series of monomeric and polymeric liquid crystal systems.

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