A D-2-NMR INVESTIGATION OF DEUTERATED CHIRAL DOPANTS IN AMPHIPHILIC CHOLESTERIC LIQUID-CRYSTALS

Several alpha-dideuterated dodecanoyl amino acids are investigated as chiral dopants with the chiral host potassium tetradecanoyl-L-alaninat e during the preparation of amphiphlic cholesteric liquid crystals. Te mperature dependent laser diffraction twist and D-2-NMR nuclear quadru polar splittings measurements are made. The temperature gradient of th e twist is thought to be a function of the micelle shape and anisotrop y. The spectral multiplicity of the prochiral alpha-deutrons in the en antiomers is not visualized through NMR and hence no direct connection could be made between the molecular and bulk chirality. In two of the chiral dopants, where the precursor amino acids are L-isoleucine and L-leucine, the smaller D-2-NMR quadrupolar splitting moves through zer o. This phenomenon is due to the molecular reorientation, where the an gle of the axis projected in the CD2 plane, which orients with respect to magnetic field direction, being near to the magic angle in respect to the CD bond.