Hoechst Aktiengesellschaft

Gerd Illian

Rainer Wingen

Anke Kaltbeitzel

Claus Escher

Hubert Schlosser

Takamasa Harada

Ingrid Muller

Norbert Rosch

Gunter Scherowsky

Michael Sefkow

Compounds for use in liquid-crystal mixtures

2-Fluoropyridines, processes for their preparation and their use in ferroelectric liquid crystal mixtures

2-Fluoropyridines, their preparation and their use in liquid crystal

2-Fluoropyrazines, process for their preparation, and their use in liquid-crystalline mixtures

2-fluoropyrazines process for their preparation, and their use in

Cyclohexylphenylpyrimidines of the formula (I) ##STR1## in which R.sup.1 is straight-chain or branched, chiral or achiral alkyl or alkenyl having 2 to 16 carbon atoms, in which one or two nonadjacent --CH.sub.2 -- groups may be replaced by --0--, --S--, --CO--, --COO--, --OCO--, --Si(CH.sub.3).sub.2 -- or --C(CH.sub.3).sub.2 --, and in which one or more hydrogen atoms of the alkyl or alkenyl radical may be replaced by fluorine atoms, and in which the terminal CH.sub.3 group of the alkyl may also be replaced by ##STR2## R.sup.2 is straight-chain or branched, chiral or achiral alkyl having 1 to 10 carbon atoms, are particularly suitable components for ferroelectric liquid-crystal mixtures since they result in favorable properties, such as, for example, high contrast, when used in electrooptical switching and display devices.

Cyclohexylphenylpyrimidines, process for their preparation, and their

Ferroelectric liquid crystal display comprising outer substrates, electrodes, polarizer(s), ferroelectric liquid crystalline material and alignment layer(s), in which the ferroelectric liquid crystalline material has a spontaneous polarization of Ps&gt;20 nC.cm.sup.-2 and a natural helical pitch of less than half of the cell thickness, and the alignment layer comprises at least one lipophilizing, lipophilic and/or amphiphilic compound. The liquid crystal display according to the invention exhibits a short switching time and a significantly reduced surface memory effect, and thus achieves an improved display contrast.

Ferroelectric liquid crystal display with liquid crystal mixtures having

Electro-optical display devices having a cell thickness of 1 to 10 .mu.m, and containing ferroelectric liquid crystalline mixture, electrodes, alignment layer(s), in which the ferroelectric liquid crystalline mixture has a spontaneous polarization of Ps&gt;20nC.cm.sup.-2 and a natural helical pitch of less than a half of the cell thickness, and contains lipophilizing, lipophilic or amphiphilic compounds for eliminating ionic impurities, Ferroelectric liquid crystal compositions according to the invention show a significantly reduced surface memory effect and an improved display contrast.

Ferroelectric liquid crystal mixtures containing lipohilizing,

Chiral oxazolidinones of the formula (I) or (II) ##STR1## in which R.sup.1 is, for example, a straight-chain or branched alkyl radical having 1 to 16 carbon atoms or

Oxazolidinone derivatives, and the use thereof as dopes in

Cyclohexylphenylpyrimidines of the formula (I) ##STR1## in which R.sup.1 is straight-chain or branched, chiral or achiral alkyl or alkenyl having 2 to 16 carbon atoms, in which one or two nonadjacent --CH.sub.2 -- groups may be replaced by --O--, --S--, --CO--, --COO--, --OCO--, --Si(CH.sub.3).sub.2 -- or --C(CH.sub.3).sub.2 --, and in which one or more hydrogen atoms of the alkyl or alkenyl radical may be replaced by fluorine atoms, and in which the terminal CH.sub.3 group of the alkyl may also be replaced by ##STR2## R.sup.2 is straight-chain or branched, chiral or achiral alkyl having 1 to 10 carbon atoms, are particularly suitable components for ferroelectric liquid-crystal mixtures since they result in favorable properties, such as, for example, high contrast, when used in electrooptical switching and display devices.

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Frankfurt am Main, Germany

Gerd Illian