Lanthanide containing Schiff's base complexes with chloride counter-ions: mesomorphic properties

Liquid crystalline lanthanide complexes (metallomesogens) with chloride cou nter-ions have been synthesized. The complexes have the stoichiometry [Ln(L H)(3)Cl-3], where Ln is a trivalent rare-earth ion (Y, Pr, Sm, Eu-Lu), and LH is the ligand N-octadecyl-4-octyloxysalicylaldimine. Although the Schiff 's base ligands do not exhibit mesomorphism, the complexes do (SmA phase). The mesomorphic behaviour of these compounds has been investigated by hot-s tage polarized microscopy, differential scanning calorimetry (DSC) and high temperature X-ray diffraction measurements. The stoichiometry of the compl exes remains constant throughout the lanthanide series. The complexes have rather high transition temperatures. (C) 2001 Elsevier Science B.V. All rig hts reserved.