Columnar phases of achiral vanadyl liquid crystalline complexes.

TitleColumnar phases of achiral vanadyl liquid crystalline complexes.
Publication TypeJournal Article
Year of Publication2000
AuthorsKilian, D, Knawby, D, Athanassopoulou, MA, Trzaska, ST, Swager, TM, Wrobel, S, Haase, W
JournalLiquid Crystals
Keywordscolumnar phase achiral vanadyl liq crystal complex

Two liq. cryst. vanadyl complexes were studied by frequency domain dielec. spectroscopy over the range 10 mHz to 13 MHz. The materials exhibit two or three columnar phases denoted Colro, Colrd, and Colhd that were identified by x-ray diffraction. In the higher temp. Colrd phase, a relaxation process in the kHz range is obsd. that is attributed to the reorientation about the mol. short axis. A pronounced dielec. relaxation process shows up in the low temp. Colro phase at hertz and sub-hertz frequencies. This slow relaxation is assigned to reorientation of the mol. dipoles within the polar linear chains, which are aligned along the column's axis. Triangular wave switching studies at low frequency reveal processes inside the Colro phase which are most probably due to ionic/charges relaxations but a ferroelec. switching for an achiral discotic system cannot be ruled out completely. Below the Colro phase there is an orientationally disordered cryst. Crx phase with disordered side chain dipoles. A dielec. relaxation process connected with the intramol. relaxation of the alkoxy side chains, similar to the $\beta$-process of polymers, was found in the lower temp. Crx phase. [on SciFinder(R)]