JOURNAL OF MAGNETIC RESONANCE 60,352-355 (1984) Two-Dimensional Deuterium Double-Quantum NMR in Partially Ordered Systems*

The NMR spectra of solute molecules in the anisotropic environment of liquid crystal solvents contain information about molecular structure and motion (I, 2). For complex molecules, the number of allowed transitions in conventional proton NMR spectra is very large, and results in extensive spectral overlaps. To reduce this, protons may be replaced by deuterons, thereby minimizing the network of spin-spin interactions, and the systems analyzed by means of deuterium high-field Fourier-transform NMR (3). Deuterium NMR spectra are dominated by residual quadrupolar interactions, each chemically shifted deuteron contributing a quadrupolar doublet to the spectrum, and the utility of high-field 2H NMR to characterize molecular ordering in such systems has been well demonstrated recently by Prestegard et al. (4). While such nuclear quadrupole coupling constants are important parameters (5) dipolar couplings between nuclei are potentially even more important sources of structural information. Unfortunately, however, ‘H NMR line widths in ordered systems (arising mainly from the distribution in quadrupolar splittings) are on th