Determination of long range dipolar couplings in ferroelectric liquid crystals

Long range dipolar coupling constants have been determined in three ferroel ectric liquid crystals in their racemic forms using C-13 NMR. Two of these liquid crystals are esters of alpha -chloroacids and 4-octyloxy-4'-hydroxyb iphenyl, and have a very large spontaneous polarization in the smectic C* p hase. The strategy used in the present study is the observation and measure ment of H-2-C-13 splittings in the C-13 spectra of monodeuterated compounds . The order parameters were calculated from the 1D spectra, and some of the coupling constants are compared with the H-1-C-13 coupling constants previ ously obtained from 2D experiments. In addition, the deuterium quadrupole s plitting of these compounds was determined from their H-2 NMR spectra. The experiments were carried out over the whole mesomorphic ranges of the liqui d crystals, covering the smectic A and smectic C phases.