New types of liquid crystal semiconductors

Abstract

Synthesis and characterization were achieved for four mesogenic complexes of
shiff’s bases (mesogenic legands) with ions of (Cu+2, Ni+2) as the following
structures:
HC=N N=CH
H H3CO 3CO OCH 3 OCH 3 (DMeOBB)
O2N HC=N N=CH NO2
(NO2BB)
(DMeOBB-Cu+2 , DMeOBB-Ni+2 , NO2BB-Cu+2 , NO2BB-Ni+2 )
The liquid crystal complexes have been characterized by a spectrophotometer
Infrared (IR), Ultra violet (UV), polarizing microscope equipped with heating stage,
Flam. atomic absorption spectrophotometer, Differential scanning calorimeter (DSC),
and Thermal gravimetry analysis (TG), techniques were found to be nematic
(enantiotropic).
The electrical measurements (D.C, and A.C) of these compounds and their
complexes have been investigated. The molar conductivity measurements for the
liquid crystal compounds (Schiff’s bases) have shown that the free liquid crystal
compounds (twin dimmers) are non electrolyte solutions, where as it’s effect of
complexation with (Cu+2,Ni+2) on the (D.C) and (A.C) values have been clear when
the (D.C) electrical conductivity ranged from (10-12) to (10-9)(ohm.cm)-1 lies in the
usual range of organic semiconductors. The (A.C) electrical conductivity increases in
the range of (10-11) to (10-6)(ohm.cm)-1.
In this work, it is found that the (D.C) conductivity increases with the following
trend:
(DMeOBB-Cu+2) > (DMeOBB-Ni+2) > (NO2BB-Cu+2) > (NO2BB-Ni+2)