Synthesis, mesomorphism, and unusual magnetic behaviour of lanthanide complexes with perfluorinated counterions

Lanthanide complexes of the Schiff base ligand 4-dodecyloxy-N-hexadecyl-2-h ydroxybenzaldimine and with perfluorinated alkyl sulfate counterions were s ynthesised. All of the metal complexes show a smectic A mesophase. The visc osity of this mesophase is much lower than that of analogous compounds with nitrate or alkyl sulfate counterions. The behaviour of these new highly an isotropic molecular magnetic materials was studied using high-temperature X -ray measurements in an external magnetic field and temperature-dependent m agnetic susceptibility measurements. The mu (eff) -versus-temperature curve is more comparable with those expected for nematic phases than for smectic phases. The luminescence spectrum of a Eu-III compound shows that the valu es of the second rank crystal field parameters are very large. The huge mag netic anisotropy can be related to this strong crystal-field perturbation.