RESUMO
Lanthanide complexes of the Schiff base ligand 4-dodecyloxy-N-hexadecyl-2-hydroxybenzaldimine and with perfluorinated alkyl sulfate counterions were synthesised. All of the metal complexes show a smectic A mesophase. The viscosity of this mesophase is much lower than that of analogous compounds with nitrate or alkyl sulfate counterions. The behaviour of these new highly anisotropic molecular magnetic materials was studied using high-temperature X-ray measurements in an external magnetic field and temperature-dependent magnetic 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 EuIII compound shows that the values of the second rank crystal field parameters are very large. The huge magnetic anisotropy can be related to this strong crystal-field perturbation.
RESUMO
The alignment of liquid crystals through magnetism demands a high value of the magnetic anisotropy. The magnitude of the anisotropy for a series of isostructural lanthanide-containing metallomesogens can be estimated on basis of the crystal-field splitting of the (7)F1 multiplet in the corresponding europium(III) compounds. A method to rapidly measure this splitting value is accessible through photoluminescence measurements.
