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

Authors: McElheny D.; Zhou M.; Frydman L.

Source: Journal of Magnetic Resonance, Volume 148, Number 2, February 2001 , pp. 436-441(6)

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Abstract:

A novel nuclear magnetic resonance (NMR) experiment for facilitating the resolution and assignment of liquid crystalline ¹³C 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 ¹³C 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 (0°, 90°) 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. Copyright 2001 Academic Press.

Keywords: mesophases; two-dimensional NMR; ¹³C chemical shift correlations; spin anisotropies; liquid crystalline polymers

Language: English

Document Type: Editorial

Affiliations: Department of Chemistry (M/C 111), University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois, 60607-7061

Publication date: 2001-02-01