Dielectric, optical and orientational properties of liquid crystalline 4-alkyloxy-4′-cyanoazoxybenzenes and 4-alkyloxy-4′-cyanoazobenzenes

Abstract

The influence of temperature on permittivity and refraction indices was studied for nematic liquid-crystalline 4-(n)alkyloxy-4′-cyanoazoxybenzenes and 4-(n)alkyloxy-4′-cyanoazobenzenes (n=4–6). The values of dielectric and optical anisotropy and orientational order parameter for nematic phase were calculated. The polarizability and dipole moments of molecules as well as their structures were calculated by DFT and AM1 methods. Kirkwood's correlation parameters were calculated as well. On the basis of experimental and calculated data the dielectric properties of mesogenic cyanoazoxybenzenes were shown to depend essentially on a mutual orientation of cyano group and NO bond of azoxy group, on a positional isomers ratio, and on an associative state.