Electro-optic characterization of novel tolane-based nematic liquid crystals

Four new tolane-based liquid crystals, 4′-pentyl-, 4′-hexyl-, and 4′-heptyl-3-fluoro-4-isothiocyanatotolane and 4′-hexyloxy-3′-fluoro-4-isothiocyanatotolane have been investigated for the first time to determine their electro-optical behavior and third order non-linearity by the static Kerr effect method. The temperature dependence of electric Kerr constant in the isotropic phase and the pretransitional behavior, related to order parameter fluctuations, have been investigated for four new high birefringence nematic liquid crystals, laterally fluorine substituted isothiocyanatotolanes in the isotropic phase. All the compounds had a positive and large Kerr constant which increased with decreasing temperature. The Landau-De Gennes model was obeyed for these compounds.