Lateral fluoro substituted 4-alkyl-4″-chloro-1,1′:4′,1″-terphenyls and derivatives. Useful high birefringence, high stability liquid crystals

By modification of the basic 4-alkyl-4″-chloro-1,1′:4′,1″-terphenyl structure with lateral fluoro substituents and ethyl linking groups, a wide range of mesogens has been synthesized. Control over the phase behaviour, especially optimization of nematic properties, can be achieved by the degree and position of lateral fluoro substitution and/or the presence and position of an ethyl linking group. The effect of these changes on the physical properties such as dielectric anisotropy (Δε) and birefringence (Δn) has also been studied. Compounds of low melting point, wide nematic range and high birefringence (>0·2) have been made. These materials are suitable for active matrix display applications where high chemical and photostability are necessary.