The synthesis and properties of fluoroterphenyls for high dielectric biaxiality ferroelectric liquid crystal mixtures

A series of liquid crystalline terphenyls with three strategically located fluoro substituents has been synthesised and evaluated for a range of physi cal properties. Low temperature metallations were used to prepared arylboro nic acids which were employed in selective palladium-catalysed cross-coupli ng reactions to generate the final liquid crystals. The syntheses are discu ssed as efficient routes to functional, multi-substituted liquid crystals. The trifluoroterphenyls have low melting points and exhibit the smectic C p hase to moderately high temperatures. The melting points, transition temper atures and mesophase morphology are discussed and compared with analogous d ifluoroterphenyls. The materials have been evaluated for a range of physica l properties and enable the formulation of ferroelectric mixtures with a hi gh dielectric biaxiality which is very important in tau V minimum driving s chemes.