Terminal trifluoromethyl-alkoxy and -alkenyloxy nematic liquid crystals for LCDs with active matrix addressing

We have synthesized a new class of compounds suitable for LCD applications, incorporating a trifluoromethyl group in the terminal alkoxy- or alkenylox y-chain. These compounds appear to fulfil many of the requirements for use in TN-LCDs. Core units containing a cyclohexyl ring, which tend to induce a lower viscosity than that of the analogous aromatic materials, were synthe sized. Systems containing several aromatic rings were also prepared with a view to producing compounds of high birefringence. Compounds containing a l ateral fluorosubstituent as well as a polar substituent in a terminal posit ion were synthesized in order to generate a high positive value of the diel ectric anisotropy. Molecules incorporating a bicyclo[2.2.2]octane ring were also synthesized in order to produce a high nematic clearing point and to influence the elastic constants. Compounds with three 1,4-disubstituted rin gs were synthesized with a view to producing materials with a high nematic clearing point and as low a melting point as possible. A series of compound s with a carbon-carbon double bond in the terminal chain was prepared in an attempt to produce compounds with appropriate values and ratios of the ela stic constants.