Hoffmann-la Roche Inc.

Frans Leenhouts

Stephen Kelly

Richard Buchecker

Alois Villiger

Martin Schadt

Optically active dopants of the formula ##STR1## wherein A represents an optically active group selected from 1,1'-binaphthyl-2,2'-diyl, --CHR.sup.1 --CHR.sup.2 -- or --CH(COOR.sub.3)--CH(COOR.sub.4)--; Z denotes a group --(CH.sub.2).sub.4 --, --O(CH.sub.2).sub.3 -- or the trans form of --OCH.sub.2 --CH.dbd.CH--; R is hydrogen, methyl, phenyl or cyclohexyl; R.sup.2 is methyl, phenyl or cyclohexyl; R.sup.3 and R.sup.4 denote alkyl; Y stands for --CO-- or --CH.sub.2 --; ring B represents 1,4-phenytene or trans-1,4-cyclohexylene; and R is hydrogen, alkyl, alkoxy or cyano, liquid crystalline mixtures which contain such dopants and their use for optical and electro-optical purposes.

Chiral dopants for liquid crystalline mixtures

Optically active compounds of the formula ##STR1## wherein m stands for the number 1 and R.sup.2 is an unsubstituted or halogen-substituted alkyl or alkenyl group in which optionally one methylene group is replaced by oxygen and/or optionally one methylene group is replaced by an ester group --COO-- or --OOC--; or m stands for the number 0 or 1 and R.sup.2 denotes a group of the formula ##STR2## R.sup.1 and R.sup.3 each independently represent an alkyl or alkenyl group in which optionally one methylene group is replaced by oxygen; Z.sup.1, Z.sup.2 and Z.sup.3 each independently are a single covalent bond, --CH.sub.2 O--, --OCH.sub.2 --, --CH.sub.2 CH.sub.2 --, --COO-- or --OOC--; n stands for the number 0 or 1; rings A.sup.1 and A.sup.2 each independently are unsubstituted or halogen, cyano and/or methyl-substituted 1,4-phenylene in which optionally 1 CH group or 2 CH groups is/are replaced by nitrogen; and C.sup.* denotes a chiral carbon atom; with the proviso that simultaneously R.sup.l does not are an alkyl group, m and n do not are the number 1, Z.sup.1 does not are the group --CH.sub.2 CH.sub.2 -- or --CH.sub.2 O-- and ring A.sup.1, Z.sup.2, ring A.sup.2 and R.sup.2 together do not are 4-(5-alkyl-2-pyrimidinyl)-phenyl, their preparation, liquid crystalline mixtures which contain these compounds and their use for electro-optical purposes.

Liquid crystalline mixtures having a chiral tilted smectic phase

Compounds of the formula ##STR1## wherein n stands for the number 0 or 1; R.sup.1 denotes a group R.sup.3 or R.sup.3 --A.sup.3 --Z.sup.2 -- and R.sup.2 denotes a group R.sup.4 or R.sup.4 --A.sup.4 --Z.sup.3 --; ring A.sup.1 is unsubstituted or halogen-, cyano- and/or methylsubstituted 1,4-phenylene in which optionally 1 CH group or 2 CH groups is/are replaced by nitrogen; A.sup.3 A.sup.4 and ring A.sup.2 each independently represent unsubstituted or halogen-, cyano- and/or methyl- -substituted 1,4-phenylene in which optionally 1 CH group or 2 CH groups is/are replaced by nitrogen or trans-1,4-cyclohexylene, trans-1,3-dioxane-2,5-diyl, 1-cyano-trans-1,4-cyclohexylene, bicyclo[2.2.2]octane- -1,4-diyl, naphthalene-2,6-diyl, tetralin-2,6-diyl or trans-decalin-2,6- diyl; Z.sup.1, Z.sup.2 and Z.sup.3 each independently are a single covalent bond, --COO--, --OOC--, --CH.sub.2 O--, --OCH.sub.2 --, --CH.sub.2 CH.sub.2 --, --C.vertline.C--, --(CH.sub.2).sub.3 O--, --O(CH.sub.2).sub.3 --, --(CH.sub.2).sub.4 -- or the trans form of --CH.dbd.CH-- CH.sub.2 O-- or --OCH.sub.2 --CH.dbd.CH--; R.sup.3 and R.sup.4 each independently denote halogen, cyano, --NCS, --CF.sub.3, --OCF.sub.3 or alkyl in which optionally one &gt;CH--CH&lt; is replaced by &gt;C.dbd.C&lt; and/or optionally one methylene group or two non- adjacent methylene groups is/are replaced by --O--, --COO-- and/or --OOC-- and/or optionally one methylene group is replaced by --CHX--; and X is halogen, cyano or methyl, as well as liquid crystalline mixtures which contain such compounds and their use for electro-optical purposes.

Cyclohexane compounds used in liquid crystalline mixtures

Optically active compounds of the formula ##STR1## wherein R.sup.1 and R.sup.2 each are alkyl with at least 2 carbon atoms; A.sup.1, A.sup.2 and A.sup.3 each are unsubstituted, cyano-, halogen- or methyl-substituted 1,4-phenylene, optionally having one or two CH groups replaced by nitrogen, unsubstituted, cyano- or methyl-substituted trans-1,4-cyclohexylene, the cyclohexylene optionally having one or two CH.sub.2 groups replaced by oxygen; Z.sup.1 and Z.sup.2 each are a single covalent bond, --COO--, --OOC--, --CH.sub.2 CH.sub.2 --, --OCH.sub.2 --, --CH.sub.2 O--, --C.tbd.C--, --COS-- or --SOC--; m stands for the number 0 or 1; n is an integer of 0 to 4; X is oxygen or a methylene group; and each C* represents a chiral carbon atom, one of the chiral carbon atoms has the R-configuration while the other has the S-configuration. The compounds are used in liquid crystalline mixtures to compensate the temperature dependence of the threshold potential of liquid crystal cells.

Optically active compounds used for liquid crystalline mixtures

Optically active compounds of the formula ##STR1## wherein m stands for the number 1 and R.sup.2 is an unsubstituted or halogen-substituted alkyl or alkenyl group in which optionally one methylene group is replaced by oxygen and/or optionally one methylene group is replaced by an ester group --COO-- or --OOC--; or m stands for the number 0 or 1 and R.sup.2 denotes a group of the formula ##STR2## R.sup.1 and R.sup.3 each independently represent an alkyl or alkenyl group in which optionally one methylene group is replaced by oxygen; Z.sup.1, Z.sup.2 and Z.sup.3 each independently are a single covalent bond, --CH.sub.2 O--, --OCH.sub.2 --, --CH.sub.2 CH.sub.2 --, --COO-- or --OOC--; n stands for the number 0 or 1; rings A.sup.1 an A.sup.2 each independently are unsubstituted or halogen, cyano and/or methyl-substituted 1,4-phenylene in which optionally 1 CH group or 2 CH groups is/are replaced by nitrogen; and C* denotes a chiral carbon atom; with the proviso that simultaneously R.sup.1 does not are an alkyl group, m and n do not are the number 1, Z.sup.1 does not are the group --CH.sub.2 CH.sub.2 -- or --CH.sub.2 O-- and ring A.sup.1, Z.sup.2, ring A.sup.2 and R.sup.2 together do not are 4-(5-alkyl-2-pyrimidinyl)-phenyl, their preparation, liquid crystalline mixtures which contain these compounds and their use for electro-optical purposes.

Compounds of the formula ##STR1## wherein R.sup.1 is alkyl or alkenyl; Z.sup.1 denotes a single covalent bond or --CH.sub.2 CH.sub.2 --; ring A represents unsubstituted or halogen- and/or methyl-substituted 1,4-phenylene; Z.sup.2 denotes a single covalent bond, oxygen or --CH.sub.2 O--; and R.sup.2 is an unsubstituted or halogen-substituted alkyl or alkenyl group,

Liquid crystalline mixtures including 2-phenylpyridine compounds

Optically active dopants of the formula ##STR1## wherein A represents an optically active group selected from 1,1'-binaphthyl-2,2'-diyl, --CHR.sup.1 --CHR.sup.2 -- or --CH(COOR.sup.3)--CH(COOR.sup.4)--; Z denotes a group --(CH.sub.2).sub.4 --, --O(CH.sub.2).sub.3 -- or the trans form of --OCH.sub.2 --CH.dbd.CH--; R.sup.1 is hydrogen, methyl, phenyl or cyclohexyl; R.sup.2 is methyl, phenyl or cyclohexyl; R.sup.3 and R.sup.4 denote alkyl; Y stands for --CO-- or --CH.sub.2 --; ring B represents 1,4-phenylene or trans-1,4-cyclohexylene; and R is hydrogen, alkyl, alkoxy or cyano, liquid crystalline mixtures which contain such dopants and their use for optical and electro-optical purposes.

A liquid crystal display (LCD) cell comprising a highly twisted nematic liquid crystal disposed between two electrode plates and polarizers and having a positive dielectric anisotropy. The optical path difference .DELTA.n.d is 0.2 to 0.7 .mu.m and the ratio d/p of thickness to pitch is 0.2 to 0.6. The absolute value of the twist angle .phi. can be between 120.degree. and 260.degree. for a right-hand twist or left-hand twist, the angle .psi. between the polarizers can be between 0.degree. and 180.degree. and the angle .beta. between the surface orientation direction and the polarization direction on the screen on the light incidence side can be between 0.degree. and 360.degree..

Liquid crystal display

A liquid crystal display (LCD) cell comprising a twist nematic liquid crystal disposed between two electrode plates and polarizers and having a positive dielectric anisotropy. The optical path difference .DELTA.n.d is 0.2 to 0.7 .mu.m. The absolute value of the twist angle .phi. can be between 10.degree. and 80.degree., the angle .psi. between the polarizers can be between 80.degree. and 110.degree. and the angle .theta. between the surface orientation direction and the polarization direction on the screen on the light incidence side can be between -10.degree. and 60.degree., preferably so that the polarizers are symmetrical of the nematic directors.

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Kaiseraugst, Switzerland

Frans Leenhouts