Rare-earth-containing magnetic liquid crystals

Rare-earth-containing metallomesogens with 4-alkoxy-N-alkyl-2-hydroxybenzal dimine ligands are reported. The stoichiometry of the complexes is [Ln(LH)( 3)(NO3)(3)], where Ln is the trivalent rare-earth ion;(Y, La, and Pr to Lu, except Pm) and LH is the Schiff base. The Schiff base ligands are in the z witterionic form and coordinate through the phenolic oxygen only. The three nitrate groups coordinate in a bidentate fashion. The X-ray single-crystal structures of the nonmesogenic homologous complexes [Ln(LH)(3)(NO3)(3)]whe re Ln = Nd(III), Tb(III), and Dy(III) and LH = CH3OC6H3(2-OH)CH=NC4H9, are described. Although the Schiff base Ligands do not exhibit a mesophase, the metal complexes do (SmA phase). The mesogenic rare-earth complexes were st udied by NMR, IR, EPR, magnetic susceptibility measurements, X-ray diffract ion,and molecular modeling. The metal complexes in the mesophase have a ver y large magnetic anisotropy, so that these magnetic liquid crystals can eas ily be aligned by an external magnetic field.