Confinement Effect in a Thick Layer of LC Lanthanide Complex

Abstract

The structure of metallomesogen complexes differs essentially from that of calamitic liquid crystals, which emerges in their physical properties. We studied anomalous features of the transition from the nematic to isotropic phase in the ytterbium-based liquid crystal complex. For this, two approaches were used. In the first approach, we showed that the experimental values of the dielectric and optical anisotropies measured near the phase transition turned out to be substantially smaller than their calculated values. This evidently occurs because the phase transition temperature in the deep region of the experimental cell differs from that near the surface of the cell. Secondly, the temperature of N–I transitions in metallomesogenic layers within glass sandwich cells is obtained directly by means of the polarization microscope method. It was found that the phase transition temperature drops in more than ten degrees when reducing the metallomesogenic layer thickness from 200 to 5 microns. The calamite liquid crystals show the confinement effect only within the interstice of the specific size smaller than one micron. An anomalous confinement effect can be caused by a strong interaction of the molecular complexes with each other.

Effect of Magnetic and Electric Field on the Orientation of Rare-Earth-Containing Nematics

“…The unique structure of such ligands allows the synthesis of thermostable nematic coordination compounds , that are capable of maintaining their original mesophase morphology upon overcooling. , The authors have proven that the compounds they synthesized are stable under applied electric fields. This stability allows a study of their alignment behavior and a determination of the value of the Kerr constant. , As opposed to the previously reported structure of the complexes with Schiff bases, these new compounds have a saturated coordination sphere that contains no counterions and includes ligands without any active functional groups. Such complexes have, therefore, limited capabilities for association in solution.…”