Synthesis and Properties of 5-Alkyl-2-(4-Cyanophenyl)Pyridines

The synthesis, physico-chemical and electro-optical properties of new nematic liquid crystal materials with a positive dielectric anisotropy-the 5-alkyl-2-(4-cyanophenyl)-pyridines-are reported. The transition temperatures, transition enthalpies, dielectric, optical, and visco-elastic properties, and also the threshold voltages and response times of the twist-effect have been measured for 2-7 homologues and binary mixtures of 5-alkyl-2-(4-cyanophenyl)pyridines (PR) containing the pentyl and heptyl components in the molar proportion 40:60. The results obtained are compared with the properties of 4-cyano-4'-n-alkyl-biphenyls (CB) and 5-n-alkyl-2-(4-cyanophenyl)pyrimidines (PY).