Abstract: The present invention relates to improved liquid crystal compounds which contain a mesogenic core which comprises a group of sub-formula (i) wherein R3 and R4 are independently selected from hydrogen, halogen or CF3, provided at least one of R3 or R4 is selected from halogen or CF3. The sub-formula (i) group may be located at any position within the mesogenic core of the liquid crystal compound, either at the terminus of the liquid crystal core or alternatively substantially in the middle of the liquid crystal core. The compounds of the invention provide compounds which when added to LC mixtures provide increasing birefringence, lowering of melting points, lowering clearing points, and lowering viscosities. These compounds and mixtures may fmd particular use in imaging or display media, such as monitors or televisions.