Abstract: Compounds of the formula (I) having side chains with multiple methyl branchesR.sup.1 (-A.sup.1 -M.sup.1).sub.a (-A.sup.2 -M.sup.2).sub.b (-A.sup.3 -M.sup.3).sub.c (-A.sup.4)-G(--C.sub.* H(CH.sub.3)--CH.sub.2).sub.n --R.sup.2 (I)where* is a chiral carbon atom;A.sup.1, A.sup.2, A.sup.3, A.sup.4 are, for example, 1,4-phenylene, pyrimidine-2,5-diyl or 1,3,4-thiadiazole-2,5-diyl;M.sup.1, M.sup.2, M.sup.3, M.sup.4 are, for example, --CO--O-- or --O--CO--;G is, for example, --CO--O--CH.sub.2, --O--CH.sub.2 -- or --O--;R.sup.2 is, for example, methyl or ethyl;a, b and c are 0 or 1 and a+b+c is 1, 2 or 3; andn is preferably 3 or 4,are suitable as components, in particular dopes, for liquid-crystalline mixtures and methods of using these compounds in liquid-crystal mixtures.

Abstract: Phenanthridine derivatives, and their use in liquid-crystalline mixturesA ferroelectric liquid-crystal mixture containing one or more phenanthridine derivatives of the formula (I) ##STR1## E.sup.1 and E.sup.2 are identical or different and are --N--, --CF-- or --CH--;R.sup.1 and R.sup.2 are identical or different and are, for example, a straight-chain or branched alkyl radical having 1 to 20 carbon atoms;Q is --CH.sub.2 --O--, --CO--O-- or a single bond;M.sup.1 and M.sup.2 are identical or different and are --CO--O--, --O--CO--, --CH.sub.2 --O--, --O--CH.sub.2 --, --CH.sub.2 --CH.sub.2 --, --C.tbd.C--, or a single bond;A.sup.1 and A.sup.

Abstract: This invention relates to novel phenanthrene derivatives of the formula (I) which are particularly suitable for use in liquid-crystal mixtures. The compounds of formula (I) have a broad range of applications. Depending on the choice of substituents, they can be used as base materials from which liquid-crystalline phases are predominantly composed. They can also be added to liquid-crystalline base materials to modify the dielectric and/or optical anisotropy of a dielectric and to optimize its threshold voltage or viscosity. Liquid-crystalline mixtures containing compounds of formula (I) are particularly suitable for use in electrooptical switching and display devices.

Abstract: A smectic liquid-crystal mixture containing rod-shaped molecules having only one side chain and certain phenylpyrimidine derivatives. The liquid-crystal mixtures according to the invention are distinguished by a low melting point and a high S.sub.C /S.sub.A phase-transition temperature. The use of bisesters of the formula I allows the number of phenylpyrimidine derivatives in the mixtures according to the invention to be significantly reduced. Ferroelectric mixtures according to the invention have, in particular, high contrast, good alignment, a large margin, low flicker and a large angle in the chevron geometry.

Abstract: A smectic liquid-crystal mixture comprisingA. at least one compound of the formula (I) ##STR1## B. at least one compound of the formula (III) ##STR2## C. compounds of the formula (IV)R.sup.1 --O--CO--O--(--A.sup.1).sub.a (--M.sup.1).sub.b (--A.sup.2).sub.c (--M.sup.2).sub.d (--A.sup.3).sub.e (--O).sub.f --R.sup.2 (IV)in which:R.sup.1 and R.sup.2 are identical or different and are a straight-chain or branched alkyl group having 1 to 22 or 3 to 22 carbon atoms respectively,A.sup.1, A.sup.2 and A.sup.3 are identical or different and are 1,4-phenylene, where one or two H atoms may also be replaced by F, 2,5-pyrimidinediyl,and further smectogenic compounds and, if desired, dopants. The mixture exhibits a low melting point and a broad S.sub.c phase.

Abstract: Smectic liquid-crystal mixture A liquid-crystalline mixture comprises, inter aliaA. at least one compound of the formula I ##STR1## and/or at least one compound of the formula (II) ##STR2## B. at least one compound of the formula (III)R.sup.1 (-A.sup.1).sub.a (-M.sup.1).sub.b (-A.sup.2).sub.c (-M.sup.2).sub.d (-A.sup.3).sub.e (-M.sup.3).sub.f (-A.sup.4)-H (III)C. and at least one compound of the formula (IV) ##STR3##The mixture has a low melting point and a broad S.sub.c phase range.