Chiral dopants

• US 6,217,792 B1
• Filed: 12/30/1998
• Issued: 04/17/2001
• Est. Priority Date: 07/01/1996
• Status: Expired due to Term

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Farrand, Louise D, Parri, Owain L, Nolan, Patrick, May, Alison
• Primary Examiner(s): Kelly, C. H.
• Application Number:
  US09/214,387
• Time in Patent Office: 839 Days
• Field of Search: 252/299.61, 428/1.1
• US Class Current: 252/299.61
• CPC Class Codes: C07D 493/04 Ortho-condensed systems
• CPC Class Codes: C09K 19/588 Heterocyclic compounds
• CPC Class Codes: C09K 2019/0448 the end chain group being a polymerizable end group, e.g. -Sp-P or acrylate
• CPC Class Codes: C09K 2219/03 in the form of films, e.g. films after polymerisation of LC precursor
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition

Abstract

The invention relates to chiral dopants of the formula (I): R¹—X¹—MG¹—G—MG²—X²—R². The invention also relates to liquid crystalline materials comprising at least one chiral dopant of formula (I) and optionally at least one polymerizable mesogenic compound. The invention furthermore relates to the use of such liquid crystalline materials for the preparation of polymer films with a chiral liquid crystalline phase, for active and passive optical elements or color filters and for liquid crystal displays, for example STN, TN, AMD-TN, temperature compensation, guest-host or phase change displays, or polymer free or polymer stabilized cholesteric texture (PFCT, PSCT) displays. The invention also relates to cholesteric liquid crystal displays comprising liquid crystalline materials comprising chiral dopants of formula (I) and to polymer films with a chiral liquid crystalline phase obtainable by (co)polymerizing a liquid crystalline material comprising at least one chiral of formula (I) and at least one polymerizable compound.

Claims

1. A chiral dopant of formula I:

2. Chiral dopants according to claim 1, wherein MG¹ and MG² are selected from the following formulae

wherein L in each case independently denotes halogen, a cyano or nitro group or an alkyl, alkoxy or alkanoyl group having 1 to 7 C atoms wherein one or more H atoms may be substituted by F or Cl and r is 0, 1 or 2.

3. Chiral dopants according to claim 2, wherein r is 0 and R¹ and R² are each independently alkyl or alkoxy with 1 to 10 C atoms.

4. A liquid crystalline material comprising at least one chiral dopant according to claim 1.

5. A liquid crystalline material comprising at least one chiral dopant according to claim 1 and at least one polymerizable mesogenic compound having at least one polymerizable functional group.

6. A liquid crystalline material comprising 0.001 to 15% of weight of at least one chiral dopant according to claim 1.

7. A liquid crystalline material comprising a liquid crystalline material according to claim 4.

8. A polymer film with a chiral liquid crystalline phase comprising at least one chiral dopant according to claim 1.

9. A polymer film with a chiral liquid crystalline phase made by a process comprising coating a liquid crystalline material according to claim 5 onto a substrate.

10. A method of preparing a polymer film with a chiral liquid crystalline phase for an optical element, a color filter, or a display comprising coating a liquid crystal material according to claim 4 onto a substrate.

11. A liquid crystalline material according to claim 4, further comprising a low molecular weight nematic or nematogenic liquid crystalline compound.

12. A liquid crystalline material according to claim 11, wherein the low molecular weight nematic or nematogenic liquid crystalline compound is selected from azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, phenyl or cyclohexyl benzoates, phenyl or cyclohexyl esters of cyclohehexanecarboxylic acid, phenyl or cyclohexyl esters or cyclohexylbenzoic acid, phenyl or cyclohexyl esters of cyclohexylcyclohexanecarboxylic acid, and of cyclohexylcyclohexanecarboxylic acid, phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclohexenes, cyclohexylcyclohexylcyclohexenes, 1,4-bis-cyclohexylbenzenes, 4,4′

-bis-cyclohexylbiphenyls, phenyl- or cyclohexylpyrimidines, phenyl- or cyclohexylpyridines, phenyl- or cyclohexylpyridazines, phenyl- or cyclohexyldioxanes, phenyl- or cyclohexyl-1,3-dithianes, 1,2-diphenylethanes, 1,2-dicyclohexylethanes, 1-phenyl-2-cyclohexylethanes, 1-cyclohexyl-2-(4-phenylcyclohexyl)ethanes, 1-cyclohexyl-2-biphenylethanes, 1-phenyl-2-cyclohexylphenylethanes, halogenated stilbenes, benzyl phenyl ether, tolanes, or substituted cinnamic acids.

13. A liquid crystalline material according to claim 4, further comprising at least one compound of the formula

14. A liquid crystalline material according to claim 5, further wherein the polymerizable mesogenic compound is of the formula P-(SP-X)_n-A-Z¹-B-(Z²-C)_p- R³

wherein

P is CH₂═

CW—

COO—

, WCH═

CH—

O,

 

or CH₂═

CH-Phenyl-(O)_k-with W being H, CH₃ or Cl and k being 0 or 1;

Sp is a spacer group having 1 to 20 C atoms;

X is a group selected from —

O—

, —

S—

, —

CO—

, —

COO—

, —

OCO—

, —

OCO—

O—

, —

S—

CO—

, —

CO—

S—

or a single bond;

n is 0 to 1;

Z¹ and Z² are each independently —

COO—

, —

OCO—

, —

CH₂CH₂—

, —

OCH₂—

, —

CH₂O—

, —

CH═

CH, —

CH≡

CH—

C—

, —

CH═

CH—

COO—

, —

OCO—

CH═

CH—

or a single bond;

wherein

A, B and C are each independently 1,4-phenylene in which, one or more CH groups may be replaced by N, 1,4-cyclohexylene in which, in addition, one or two non-adjacent CH₂ groups may be replaced by O and/or S, 1,4-cyclohexenylene, 1,4-bicyclo(2,2,2)octylene, piperidine-1,4-diyl,naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, or 1,2,3,4-tetrahydro-naphthalene-2,6-diyl;

optionally all these groups are unsubstituted, mono- or polysubstituted with halogen, cyano or nitro groups, or alkyl, alkoxy or alkanoyl groups having 1 to 7 C atoms wherein one or more H atoms may be substituted by F or Cl;

p is 0, 1 or 2; and

R³ is an alkyl radical with up to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, optionally one or more non-adjacent CH₂ groups are replaced, independently from one another, by —

O—

, —

S—

, —

NH—

, —

N(CH₃), —

CO—

, —

COO—

—

OCO—

, —

OCO—

O—

, —

S—

CO—

, —

CO—

S—

or —

C≡

C—

with the proviso that oxygen atoms are not linked directly to one another, or alternatively, R³ is halogen, cyano or is independent from P-(Sp-X)_n-.

15. A liquid crystalline material according to claim 5, wherein the polymerizable mesogenic compound is at least one of the following formulae:

wherein x and y are each independently 1 to 12, D is a 1,4-phenylene or 1,4-cyclohexylene, R is selected from the group consisting of halogen, cyano and an alkyl or alkoxy with 1 to 12 C atoms, and L¹ and L² are each, independently, selected from the group consisting of H, halogen, CN, and an alkyl, alkoxy or alkanoyl with 1 to 7 C atoms.

16. A liquid crystalline material according to claim 4, further comprising at least one of a catalyst, a sensitizer, a stabilizer, a co-reacting monomer, or a surface-active compound.

17. A liquid crystal display, optical element, or color filter comprising a chiral dopant according to claim 1.

18. The display of claim 17, wherein the display is selected from the group consisting of a STN, TN, AMD-TN, temperature compensation, guest-host, phase change, polymer free cholesteric texture, and polymer stabilized cholesteric texture display.

19. A chiral dopant of formula I according to claim 1 wherein MG¹ and MG² are different.

20. A liquid crystalline material comprising at least one chiral dopant of formula I:

21. The liquid crystalline material according to claim 20, wherein MG¹ and MG² of the chiral dopant are selected from the following formulae

22. A liquid crystalline material according to claim 20, wherein the chiral dopant has r=0 and R¹ and R² are each independently alkyl or aloxy with 1-10 carbon atoms.

23. A liquid crystalline material according to claim 20, wherein MG¹ and MG² are different.

24. A polymer film with a chiral liquid crystalline phase comprising at least one chiral dopant of formula I