# US 4,391,489 A · Liquid crystal materials containing pleochroic anthraquinone dyes > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,391,489 A - Document ID: US4391489A - Status: Granted - Kind: A - Application number: 06/287,123 - Filed: 1981-07-27 - Granted: 1983-07-05 - Earliest claimed: 1980-07-29 - Assignees: The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland - Inventors: Kenneth J. Harrison; Edward P. Raynes; Frances C. Saunders; David J. Thompson - Web page: https://patentgrep.com/patent/US4391489A ## CPC - C09B 1/503: unsubstituted amino-hydroxy anthraquinone - C09B 1/515: N-alkyl, N-aralkyl or N-cycloalkyl derivatives - C09B 1/545: {Anthraquinones with aliphatic, cycloaliphatic or araliphatic ether groups} - C09K 19/603: {Anthroquinonic} - C09B: ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES {, e.g. PIGMENTS}; MORDANTS; LAKES (fermentation or enzyme using processes to synthesise a desired chemical compound C12P) - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE ## Abstract A material suitable for a guest-host liquid crystal device comprises a solution of a liquid crystal material and a pleochroic dye wherein the pleochroic dye comprises at least one compound having a formula: ##STR1## wherein one of X and Y is OH and the other is NHR wherein R is H or lower alkyl; each of R.sub.1 and R.sub.2 independently represents alkyl, aryl, aralkyl, alkoxy or --NR.sub.3 R.sub.4 wherein each of R.sub.3 and R.sub.4 is independently H or lower alkyl, provided that R.sub.2 is always adjacent to an OH group. ## Claims ### Claim 1 A material suitable for a guest-host liquid crystal device comprising a solution of a liquid crystal material and a pleochroic dye wherein the pleochroic dye comprises at least one compound having a formula: ##STR34## wherein R is H or lower alkyl; and each of R.sub.1 and R.sub.2 independently represents alkyl containing between 1 and 10 carbon atoms. ### Claim 2 (depends on 1) A material as claimed in claim 1 in which R.sub.1 and R.sub.2 are independently alkyl groups containing between 4 and 10 carbon atoms. ### Claim 3 (depends on 1) A material as claimed in claim 1 in which each of R.sub.1 and R.sub.2 is independently a group ##STR35## where R.sub.x and R.sub.y are alkyl groups. ### Claim 4 (depends on 1) A material as claimed in claim 1 in which the compound is 4,5-diamino-2,7-di-isobutyl-1,8-dihydroxyanthraquinone, the groups R.sub.1 and R.sub.2 both isobutyl groups. ### Claim 5 (depends on 1) A material as claimed in claim 1 in which the compound is 4,5-diamino-2,7-dinonyl-1,8-dihydroxyanthraquinone, the groups R.sub.1 and R.sub.2 being n-C.sub.9 H.sub.19 groups. ### Claim 6 (depends on 1) A material as claimed in claim 1 in which the liquid crystal material includes one or more cyanobiphenyl liquid crystal compounds. ### Claim 7 (depends on 6) A material as claimed in claim 6 in which the liquid crystal material is composed mainly, as a percentage by weight, of cyanobiphenyl compounds. ### Claim 8 (depends on 1) A material as claimed in claim 1 in which the liquid crystal material includes one or more cyanophenylcyclohexane liquid crystal compounds. ### Claim 9 (depends on 8) A liquid crystal material as claimed in claim 8 in which the liquid crystal material is composed mainly, as a percentage by weight, of cyanophenylcyclohexane compounds. ### Claim 10 (depends on 1) A material as claimed in claim 1 in which the liquid crystal material is a nematic material suitable for a Freedericksz effect or twisted nematic effect device. ### Claim 11 (depends on 1) A material as claimed in claim 1 in which the liquid crystal material is a long pitch cholesteric material suitable for a cholesteric-to-nematic phase change liquid crystal material formed of a mixture of a nematic material and a chiral material. ### Claim 12 (depends on 11) A material as claimed in claim 11 in which the nematic material is composed mainly, as a percentage by weight, of cyanobiphenyl compounds. ### Claim 13 (depends on 12) A material as claimed in claim 12 in which the chiral material is 4-[(+)-2-methylbutyl]-4'-cyanobiphenyl and forms less than 10% by weight of the mixture of nematic and chiral materials. ### Claim 14 (depends on 13) A material as claimed in claim 13 in which the nematic material is a material composed mainly of cyanobiphenyl compounds and the chiral material 4-(+)-2-methylbutyl-4'-cyanobiphenyl forms about 5% by weight of the mixture of nematic and chiral materials. ### Claim 15 (depends on 1, 33) A material as claimed in claim 1 in which the pleochroic dye comprises a mixture of dyes of different color, at least one comprising a compound having Formula (I) as defined in claim 33. ### Claim 16 (depends on 15) A material as claimed in claim 15 in which the compound having Formula (I) is a blue dye compound. ### Claim 17 (depends on 16) A material as claimed in claim 16 in which the blue dye compound is selected from: 4,5-diamino-2,7-di-isobutyl-1,8-dihydroxyanthraquinone, and 4,5-diamino-2,7-dinonyl-1,8-dihydroxyanthraquinone. ### Claim 18 (depends on 15) A material as claimed in claim 15 in which the dye compound having Formula (I) is mixed together with a yellow dye and a red dye. ### Claim 19 (depends on 18) A material as claimed in claim 18 in which at least one of the yellow dye and red dye has a formula: ##STR36## wherein R is aryl or alkyl, Q is halogen, hydroxy, anino, alkylamino, dialkylamine, nitro, alkyl, or aryl, x is an integer of from 1 to 4 inclusive, and y is an integer of from 0 to 4 inclusive. ### Claim 20 (depends on 19) A material as claimed in claim 19 in which at least one of the yellow dye and the red dye comprises a compound having a formula: ##STR37## wherein R.sub.C and R.sub.D are groups selected from thiophenyl and 4-alkylthiophenyl groups and X.sup.1 and X.sup.2 are either both hydrogen or are groups selected from thiophenyl and 4-alkylthiophenyl groups. ### Claim 21 (depends on 20) A material as claimed in claim 20 in which the yellow dye comprises a dye compound of Formula (VI) as defined in claim 20, X.sup.1 and X.sup.2 being hydrogen, and the red dye comprises a dye compound of Formula (VI) as defined in claim 20, X.sup.1 and X.sup.2 being groups selected from thiophenyl and 4-alkylthiophenyl. ### Claim 22 (depends on 21) A material as claimed in claim 21 in which the blue dye comprises a compound selected from: 4. 5-diamino-2,7-di-isobutyl-1,8-dihydroxyanthraquinone, and 4,5-diamino-2,7-dinonyl-1,8-dihydroxyanthraquinone. ### Claim 23 (depends on 1) A liquid crystal electro-optical device comprising two electrically insulating substrates at least one of which is optically transparent, electrodes on the inner surfaces of the substrates and a film of dielectric material contained between the electrodes and the substrates, wherein the improvement comprises the dielectric material being material as claimed in claim 1. ### Claim 24 (depends on 23) A device as claimed in claim 23 in which the device is a Freedericksz effect or twisted nematic effect device. ### Claim 25 (depends on 23) A device as claimed in claim 23 in which the device is a cholesteric to nematic phase change effect device, the dielectric material being a long pitch cholesteric material.