Measurement of Interproton, Nuclear Spin Dipolar Couplings in Liquid Crystalline Samples by Combining Variable Angle Sample Spinning, Isotope Dilution, and Deuterium Decoupling

The proton NMR spectra of liquid crystalline samples can be simplified by selective, partial deuteration followed by deuterium decoupling. This leaves strong peaks from the protons at the undeuterated sites, but also weak resonances from the coupling of these protons to those at low abundance (2% in the present case) at the deuterated sites. The weak resonances can be separated from the strong by recording spectra while spinning the sample at a series of angles to the magnetic field.