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Updated: Aug 7, 2026

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Solid-state NMR characterization and determination of the orientational order of a nematogen
T Narasimhaswamy1, M Monette, D K Lee
1Department of Chemistry and Biophysics Research Division, University of Michigan, Ann Arbor, Michigan 48109-1055, USA.
Abstract:
Thermotropic liquid crystalline compounds are of considerable importance due to their potential applications as advanced functional materials. A mesogen consisting of a terminal dimethylamino group, which can act as a charge-transfer donor, is particularly valuable for its light emission and nonlinear optical properties. In this study, we report the solid-state NMR investigation of the nematic behavior of one such novel mesogen (4-(dodecyloxy)benzoic acid 4-[((4-(dimethylamino)phenyl)imino)methyl]phenyl ester). Static and MAS experiments were performed on nematic and crystalline phases of the compound to measure (13)C chemical shift, (13)C-(1)H dipolar coupling, and (1)H chemical shift values. 2D chemical shift correlation of (1)H and (13)C nuclei confirmed the (13)C chemical shift values determined from 1D CPMAS experiments. The appearance of more peaks in both CPMAS and (13)C-(1)H HETCOR spectra of a crystalline solid suggests the heterogeneous orientations of phenyl rings of the mesogenic core. Variable-temperature experiments infer the motional averaging of these orientations before melting. The (1)H-(13)C dipolar coupling values, measured by 2D PITANSEMA experiments, were used to determine the orientational order of the mesogenic core at various temperatures. The influence of the linking unit and terminal substituents on the order parameter values of the mesogenic core is discussed.
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