Mesomorphism of lanthanide-containing Schiff's base complexes with dodecylsulphate counterions

Liquid crystalline complexes of the formula [Ln(LH)(3)(DOS)(3)] have been s ynthesized, where Ln is a trivalent rare earth-ion (Y, La-Lu, except Pm), L H is the ligand N-octadecyl-4-tetradecyloxysalicylaldimine and DOS is the d odecyl sulphate counterion. Although the Schiff's base ligands do not exhib it mesomorphism, the complexes do (SmA phase). The mesophase behaviour of t hese compounds has been investigated by polarizing optical microscopy, diff erential scanning calorimetry, high temperature X-ray diffraction and therm ogravimetric analysis. The stoichiometry of the complexes remains constant throughout the lanthanide series.