Conductance and dielectric anisotropy properties of 4-cyano-4′-hexylbiphenyl-salicylaldimine compound composite liquid crystal exhibiting large positive dielectric anisotropy

The electronic properties of 4-cyano-4′-hexylbiphenyl and salicylaldimine compound 1 liquid crystals have been investigated. The polarizing microscopy and differential scanning calorimetry results show that chiral salicylaldimine compound 1 exhibits enantiotropic smectic A* and SmC* mesophases. The novel 4-n-hexyl-4′-cyanobiphenyl/salicylaldimine compound 1 composite showed an extremely large positive dielectric anisotropy. The dielectric anisotropy of the LCs changes from positive type to negative type. The critical frequency f_c values of dielectrical anisotropy for 4-n-hexyl-4′-cyanobiphenyl and salicylaldimine compound 1 LCs were found to be 630.50 and 813.01 kHz, respectively. The splay elastic constant K₁₁ values of the liquid crystals were calculated and the doping of salicylaldimine compound 1 into 4-cyano-4′-hexylbiphenyl liquid crystal increases the splay elastic constant of 6CB. The parallel conductivity σ_∥ values of the liquid crystals are higher than that of perpendicular conductivity σ_⊥ values and conductivity of the 4-cyano-4′-hexylbiphenyl decreases with doping of salicylaldimine compound 1.