摘要 |
The invention relates to compounds of the formula I and to a liquid-crystalline medium based on a mixture of polar compounds of positive dielectric anisotropy, characterized in that it comprises one or more compounds of the general formula I in which R, A<SUP>1</SUP>, A<SUP>2</SUP>, Z<SUP>1</SUP>, Y, Z, L<SUP>1</SUP>, L<SUP>2 </SUP>and m are as defined herein. |