Enhanced conductivity and dielectric absorption in discotic liquid crystalline columnar phases of a vanadyl complex.

A liq. cryst. vanadyl complex was studied by DSC, polarizing optical microscopy, the reversal current technique, x-ray diffraction and frequency domain dielec. spectroscopy. The compd. exhibits three columnar phases: rectangular ordered (Colro), rectangular disordered (Colrd), and hexagonal disordered (Colhd), all of which show a dielec. relaxation process at low frequencies. In the Colro low temp. phase this process seems to be connected with a slow relaxation of polarized polymeric chains inside the columns (mHz frequency range). However, in the Colhd high temp. disordered phase this relaxation is faster (Hz range). It is interesting that the liq. cryst. phases studied show enhanced cond. which changes by four orders of magnitude from 10-9 S m-1 in the orientationally disordered crystal (an ODIC phase) to 10-5 S m-1 in the Colhd high temp. phase. Such a value of the cond. is typical for semiconducting materials. [on SciFinder(R)]