Stable Liquid Crystals with Large Negative Dielectric Anisotropy-I

The introduction of one lateral cyano group in the 4-n-alkyl phenyl esters of different aromatic and alicyclic acids strongly depresses their clearing points and does not lead to large negative Δϵ. The 2,3-dicyano hydroquinone derivatives possess the required Δϵ but are photochemically unstable. The effect of the 2,3-dicyano substituents on the N-I transition is almost the same as that of the 2-cyano group.