Abstract: 2,5-substituted 1,3,4-thiadiazoles of the general formula ##STR1##The aforementioned compounds are used in amounts of 0.1 to 80 mole percent in mixtures for electrooptical arrangements for the modulation of transmitted and reflected light, as well as for the colored or black-and-white display of numerals, symbols and moving or still pictures. The compounds endow the liquid-crystalline mixtures with an extended phase field of the smectic C phase, negative dielectric anisotropy and the property of forming optically active C phases upon admixture with optically active compounds.

Abstract: Fast-switching displays with memory properties are provided, which can display digits, symbols, and images, and which contain as chemically and thermally stable ferroelectric liquid crystalline substances, according to the invention, liquid crystalline derivatives which contain a chiral alkyl halide residue corresponding to the general formula ##STR1## are used in mixtures of one another as well as in conjunction with other liquid crystalline or non-crystalline liquid substances.

Abstract: A mixing component for nematic liquid-crystalline substances used in optoelectronic components for the rendition of numbers, symbols and images. The object of the invention is to reduce, in components for nematic liquid crystal substances, the threshold and operating voltages. It has been found, that the addition of one or more 1-oxa-2,6,7-trioxane-1-phospha-bicyclo-derivatives having the general formula ##STR1## wherein ##STR2## with R.sup.1 =C.sub.n H.sub.2n+1 --, C.sub.n H.sub.2n+1 O--, C.sub.n H.sub.2n+1 COO--, C.sub.n H.sub.2n+1 OCOO--, R.sup.2 +C.sub.n H.sub.2n=1 --with n=an integer from 1 to 10to nematic liquid crystal substances, considerably reduces the operating voltage.

Abstract: The invention relates to liquid crystal compounds for the guest-host effect having a positive contrast, pure red color and exhibiting excellent stability. The compounds herein are derivatives of tetrazine of the general formula: ##STR1## in which m and n are 1 to 10. Other related compounds, mixtures and compositions thereof, and opto-electronic displays are described also.

Abstract: This invention relates to new nematic liquid crystal substances for electro-optical components.The object of this invention is to create substances for electro-optical components combining chemical and thermal stability with low melting and high clear points at low operational voltage, as well as to processes for their production.It has been found that new liquid-crystal trans-6-n-alkyl-decalin-2-carbonic acid ester of the general formula ##STR1## can be introduced into electro-optical components. These substances are produced by the catalytic high-pressure hydrogenation of 6-n-alkylnaphthalene-2-carbonic acids, separation of the trans-isomers by distillation, and esterification with the corresponding hydroxy compounds of the acyl chlorides obtained through reaction with thionyl chloride.

Abstract: A nematic liquid crystal compound adapted for the modulation of the transmitted or incident light and reproduction in color of numerals, symbols and images by electro-optical devices, the said compound having the formula ##STR1## wherein R.sup.1 .dbd.Br--, Cl--, C.sub.n H.sub.2n+1 --, C.sub.n H.sub.2n+1 O--, n being 1 to 10,R.sup.2 .dbd.C.sub.n H.sub.2n+1 --, n being 2 to 10,R.sup.3 .dbd.C.sub.n H.sub.2n+1 --, C.sub.n H.sub.2n+1 O--, n being 1 to 10,R.sup.4 .dbd.C.sub.n H.sub.2n+1 --, C.sub.n H.sub.2n+1 O--, n being 1 to 10.

Abstract: Liquid crystal compound for color modulation of light in electro-optical devices characterized by an oriented smectic C-phase with positive dielectric anisotropy. The compound has the property of a dichroitic dyestuff.

Abstract: A nematic liquid crystal mixture for modulation of the transmitted or incident light and for rendition of colored numerals, symbols and images in electro-optical devices, the said mixture comprising(a) a nematic liquid crystal adapted for reorientation in an electrical field due to its dielectric anisotropy and(b) a dichroic dyestuff adapted for simultaneous orientation changes together with the said nematic liquid crystal between a light absorption and a light transmission position based on the guest-host effect, the said dyestuff being an s-tetrazine derivative having an elongate molecular structure and having the formula ##STR1## wherein X is ##STR2## R.sup.1 and Y is R.sup.2 -- or ##STR3## R.sup.1 being H--, F--, Cl--, Br--, J--, O.sub.2 N--, NC--, HO--, H.sub.2 N--, C.sub.n H.sub.2n+1 NH--, C.sub.n H.sub.2n+1 (CH.sub.3)N--, C.sub.n H.sub.2n+1" --, C.sub.n H.sub.2n+1 O--, C.sub.n H.sub.2n+1 S--, C.sub.n H.sub.2n+1 COS--, C.sub.n H.sub.2n+1 COO--, C.sub.n H.sub.2n+1 OOC--, C.sub.n H.sub.2n+1 CO-- or C.sub.