Syntheses and Mesophase Characteristics of Some Oxovanadium(IV)-Chiral Schiff's Base Complexes

Abstract

Three oxovanadium(IV) complexes of derivatives of chiral Schiff's bases have been synthesized and their properties investigated, Structure 1. They were similarly found to show only chiral nematic phases, while the intermediates exhibited some other phases, i.e., chiral smectic C and blue phases. Surprisingly, as the structures are in accordance to an ideal mesogenic moiety, the ester starting materials were non-mesogenic. This may be due to a rather weak intermolecular interaction of the ester groups in the adjacent molecules. Until after the hydrolyses of the esters that two from three of the resulting acid could form liquid crystal phases, two chiral smectic C and a chiral nematic phases. Then, condensing with 4-hydroxybenzaldehyde, again, gave another non-mesogenic intermediates. In contrast with the starting materials, these compounds might possess much higher intermolecular interaction for the molecules to form mesophases. On the formation of the imine derivatives, the Schiff's base ligand without oxygen showed a distinct Blue Phase II (BPII) texture. Finally, the oxovanadium(IV) complexes all showed only chiral nematic phases.