Chiral additives for cholesteric displays

• US 6,830,789 B2
• Filed: 09/24/2001
• Issued: 12/14/2004
• Est. Priority Date: 06/09/2000
• Status: Expired due to Fees

• Current Assignee: Kent Displays Incorporated
• Original Assignee: Kent Displays Incorporated, Kent State University
• Inventors: Khan, Asad A., Doane, Joseph W., Seed, Alexander J.
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US09/937,210
• Publication Number:
  US 20020187281A1
• Time in Patent Office: 1,177 Days
• Field of Search: 428/1.1, 252/299.01, 252/299.62, 252/299.7, 549/430, 549/453
• US Class Current: 428/1.3
• CPC Class Codes: C07B 2200/07 Optical isomers
• CPC Class Codes: C07D 317/20 Free hydroxyl or mercaptan
• CPC Class Codes: C09K 19/588 Heterocyclic compounds
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/03 Viewing layer characterised by chemical composition
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal

Abstract

A unique class of chiral additive materials is disclosed for use in cholesteric displays that possess a helical twist power substantially independent of temperature. The additives have a solubility and a helical twist power large enough to be used as a single chiral component with little dilution of the physical properties of the nematic liquid crystal host mixture. The chiral additives may be used in combination with non-chiral additives to provide a helical twisting power substantially independent of temperature suitable for cholesteric displays.

Claims

1. An optically active compound of the formula:

where the R₂ and R₃ groups are a lower alkyl group or an aryl or biaryl unit while the R₁ groups independently each are a hydroxyl, alkoxyl, aryloxy, or arylalkoxy group, the R groups each represent a group as follows;

2. The optically active compound of claim 1, where each R substituent is independently selected as:

where R₄ represents a group as follows;

3. The optically active compound of claim 2, where R₄ is an aryloxy radical, an arylalkoxy radical, an arylalkyleneoxy, or an arylalkenyleneoxy radical.

28. The optically active compound of claim 1, where each R substituent is independently selected as:

where R₄ is an aryloxy radical, an arylalkoxy radical, an arylalkyleneoxy, or an arylalkenyleneoxy radical.

4. (4R,5R)-2,2-dimethyl-α

,α

,α

′

,α

′

-tetrakis[6-(benzyloxy)naphth-2-yl]-1,3-dioxolane-4,5-dimethanol.

5. A liquid crystalline mixture, comprising:

a liquid-crystalline base having liquid crystalline properties;

at least one optically active compound of the formula;

where R₂ and R₃ are a lower alkyl group or an aryl or biaryl unit while the R₁ groups independently each are a hydroxyl, alkoxyl, aryloxy, or arylalkoxy group, the R groups each represent a group as follows;

6. The liquid crystalline mixture of claim 5, where each R substituent is independently selected as:

where R₄ represents a group as follows;

7. The liquid crystalline mixture of claim 6, where R₄ is an aryloxy radical, an arylalkoxy radical, an arylalkyleneoxy, or an arylalkenyleneoxy radical.

8. The liquid crystalline mixture of claim 5, further including an achiral non-liquid crystalline compound.

9. The liquid crystalline mixture of claim 8, wherein the achiral non-liquid crystalline compound comprises R¹—

C≡

N, where R¹ represents an aliphatic group.

10. The liquid crystalline mixture of claim 9, wherein R¹—

C≡

N represents an alkylnitrile.

11. The liquid crystalline mixture of claim 9, wherein R¹—

C≡

N represents undecanenitrile.

29. The liquid crystalline mixture of claim 5, where each R substituent is independently selected as:

where R₄ is an aryloxy radical, an arylalkoxy radical, an arylalkyleneoxy, or an arylalkenyleneoxy radical.

12. A liquid crystalline mixture, comprising:

a liquid-crystalline base having liquid crystalline properties;

at least one optically active compound of the formula (4R,5R)-2,2-dimethyl-α

,α

,α

′

,α

′

-tetrakis[6-(benzyloxy)naphth-2-yl]-1,3-dioxolane-4,5-dimethanol.

13. The liquid crystalline mix of claim 12, further including an achiral non-liquid crystalline compound.

14. The liquid crystalline mixture of claim 13, wherein the achiral non-liquid crystalline compound comprises R¹—

C≡

N, where R¹ represents an aliphatic group.

15. The liquid crystalline mixture of claim 14, wherein R¹—

C≡

N represents an alkylnitrile.

16. The liquid crystalline mixture of claim 14, wherein R¹—

C≡

N represents undecanenitrile.

17. An electro-optical cell comprising a layer including a liquid crystalline mixture sandwiched between two substrate means, and means for applying an electric potential to the substrate means, wherein the liquid crystalline mixture comprises:

a liquid-crystalline base having liquid crystalline properties;

at least one optically active compound of the formula;

where the R₂ and R₃ groups are a lower alkyl group or an aryl or biaryl unit while the R₁ groups independently each are a hydroxyl, alkoxyl, aryloxy, or arylalkoxy group, the R groups each represent a group as follows;

18. A light modulating apparatus comprising said electro-optical cell of claim 17.

19. The light modulating apparatus of claim 18, wherein the light modulating apparatus comprises a cholesteric display.

30. The electro-optical cell of claim 17, where each R substituent is independently selected as:

where R₄ is an aryloxy radical, an arylalkoxy radical, an arylalkyleneoxy, or an arylalkenyleneoxy radical.

20. A electro-optical cell comprising a layer including a liquid crystalline mixture sandwiched between two substrate means, and means for applying an electric potential to the substrate means, wherein the liquid crystalline mixture, comprises:

a liquid-crystalline base having liquid crystalline properties;

at least one optically active compound of the formula (4R,5R)-2,2-dimethyl-α

,α

,α

′

,α

′

-tetrakis[6-(benzyloxy)naphth-2-yl]-1,3-dioxolane-4,5-dimethanol.

21. A light modulating apparatus comprising said electro-optical cell of claim 20.

22. The light modulating apparatus according to claim 21, wherein the light modulating apparatus comprises a cholesteric display.

23. An electro-optical cell comprising:

a layer comprising;

at least 70 weight percent (wt %) nematic host mixture; and

at least about 2 wt % (4R,5R)-2,2-dimethyl-α

,α

,α

′

,α

′

-tetrakis[6-(benzyloxy)naphth-2-yl]-1,3-dioxolane-4,5-dimethanol;

first and second substrates disposed above and below, respectively, the layer, and

first and second conductors physically coupled to the first and second substrates, respectively, which permit an electrical potential to be applied across the layer.

24. The electro-optical cell of claim 23, wherein the layer further comprises about 2-6 wt % achiral material.

25. The electro-optical cell of claim 23, wherein the layer further comprises a chiral material different from (4R,5R)-2,2-dimethyl-α

,α

,α

′

,α

′

-tetrakis[6-(benzyloxy)naphth-2-yl]-1,3-dioxolane-4,5-dimethanol and having an opposite twist sense.

26. A light modulating apparatus comprising said electro-optical cell of claim 23.

27. The light modulating apparatus of claim 26, wherein the light-modulating apparatus comprises a cholesteric display having a temperature independent reflective wavelength.