SYNTHESIS AND MAGNETIC INVESTIGATIONS ON RARE-EARTH-CONTAINING LIQUID-CRYSTALS WITH LARGE MAGNETIC-ANISOTROPY

A new series of liquid-crystalline Schiff base lanthanide compounds of the general formula (L''H)(2)L''MX(2) was prepared (L''H = H2n+1CnOC6 H3(OH)CHNCmH2m+1; n = 7, 12; m = 14, 18; M = La, Tb, Dy, Er, Nd, Ho, E u, Pr, and Gd; X = NO3 or Cl). The thermal behavior of these complexes was examined by polarizing microscopy, differential scanning calorime try, and X-ray diffraction experiments. The ligands L''H are nonmesomo rphic, but all lanthanide complexes show smectic A mesophases. Further , temperature-dependent magnetic susceptibility measurements were carr ied out in order to obtain information about the magnetic anisotropy o f the lanthanide compounds. The Tb(III) and Dy(III) derivatives could be oriented by a magnetic field. These liquid-crystalline lanthanide c omplexes display magnetic anisotropies which are two orders of magnitu de greater than those of known liquid crystals.