Hoechst Aktiengesellschaft

Anke Kaltbeitzel

Rainer Wingen

Hubert Schlosser

Gerd Illian

Takamasa Harada

Claus Escher

Norbert Rosch

Javier Manero

Gunter Scherowsky

Claas Junghans

Britta Michalski

Compounds for use in liquid-crystal mixtures

Chiral oxiranylmethyl ethers, and their use as dopants 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

A 3-fluoropyridine of the formula (I) ##STR1## in which the symbols have the following meanings: R.sup.1 and R.sup.2, independently of one another, are, for example, H or straight-chain or branched alkyl, A.sup.1, A.sup.2, A.sup.3 and A.sup.4 are identical or different and are, for example, 1,4-phenylene, pyrazine-2,5-diyl or trans-1,4-cyclohexylene, M.sup.1, M.sup.2, M.sup.3 and M.sup.4 are identical or different and are, for example, --O-- or --CO--O--, R.sup.3, R.sup.4, R.sup.6 and R.sup.7, independently of one another are, for example, H or straight-chain or branched alkyl, M.sup.5 is for example, --O--CO-- or a single bond, k, l, m, n, o, p, q and r are zero or one, with the proviso that the sum k+m+p+r is less than 4 and greater than zero, can advantageously be employed as a component in ferroelectric liquid-crystal mixtures.

3-fluoropyridines, process for their preparation, and their use in

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

Azetidinones of the formula I ##STR1## in which, for example, R.sup.1 is an alkyl or alkenyl radical, R.sup.2 and R.sup.3 are hydrogen or an alkyl or alkenyl radical, Z is hydrogen or (pseudo)halogen, A.sup.1, A.sup.2 and A.sup.3 are a ring system, and M is a spacer group, can be added to liquid-crystal mixtures. Even when admixed in small amounts, they cause considerable twist in the cholesteric and smectic C* phase, which can compensate the pitch of another dope or produce a short S.sub.C * pitch.

Chiral azetidinone derivatives, and their use as dopes in liquid-crystal

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.

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Russelsheim, Germany

Anke Kaltbeitzel