Nematic liquid crystals with a tetrafluoroethylene bridge in the mesogeniccore structure

A dramatic increase of the clearing temperatures of liquid crystals based o n bis(cyclohcxyl)ethane 1 by 50 to 70 K can be achieved by the perfluorinat ion of the central ethylene link. Conformational analysis indicates that th is effect is due to the increased rigidity of the mesogenic core structure and to the suppression of conformers with a bent shape. Materials based on bis(cylohexyl)tetrafluoroethane 2 might play a crucial role as materials fo r the next generation of active matrix LCDs with reduced power consumption.