Discotic compounds for use in liquid crystal mixtures

Details Discotic compounds for use in liquid crystal mixtures Discotic compounds for use in liquid crystal mixtures

1996-02-28

1998-05-12

Wu, Shean C.

Compositions

Liquid crystal compositions

Containing nonsteryl liquid crystalline compound of...

560 56, 560 64, 560 80, 428 1, C09K 1932, C09K 1952, C07C 6976

Patent

active

057500509

DESCRIPTION:

BRIEF SUMMARY
This is a national phase filing of PCT/GB93/01291 having an international filing date of Jun. 16, 1993, published as WO94/29263 Dec. 22, 1994.


BACKGROUND OF THE INVENTION

This invention relates to discotic compounds and to their use in liquid crystalline materials and liquid crystal devices.
The majority of known liquid crystalline compounds have a generally rod-shaped molecular structure, and are often characterised by nematic and/or smectic mesophases. However, there are a number of known compounds which are characterised by a generally disc-like molecular structure. These compounds are termed discotic compounds, which can be characterised by anisotropic mesophase(s).
Discotic compounds can be based on a number of "cores", eg benzene, truxene, metallophthalocyanine and triphenylene described in S Chandrasekhar and G S Ranganath in Rep Prog Phys 53 (1990) pp 57-84. Nguyen Huu Tinh et al (Mol. Cryst. Liq. Cryst., (1981), Vol 68, pp 101-111) describe 2,3, 6,7, 10,11 triphenylene n-alkoxy (and n-alkyl) esters. C Vauchier et al (Mol. Cryst. Liq Cryst., Vol 66 (1981) pp 103-114) have also described 2,3, 6,7, 10,11 n-alkoxy benzoates and n-alkoxy tetra-fluoro substituted benzoates of triphenylene.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a synthetic route for preparing the compound of Example 1.
FIG. 2 is a synthetic route for preparing the compound of Example 2;
FIG. 3 is a synthetic route for preparing the compound of Example 3;
FIG. 4 is a synthetic route for preparing the compound of Example 4;
FIG. 5 is a synthetic route for preparing the compound of Example 5;
FIG. 6 is a synthetic route for preparing the compound of Example 6;
FIG. 7 is a synthetic route for preparing the compound of Example 7;
FIG. 8 is a phase diagram illustrating weight percent of a mixture of two compounds versus temperature;
FIG. 9 is a phase diagram illustrating weight percent of compound versus temperature for selected compounds of pairs of compounds;
FIG. 10 is a phase diagram illustrating weight percent of compound versus temperature for selected compounds of pairs of compounds;
FIG. 11 is a phase diagram illustrating weight percent of compound versus temperature for selected compounds of pairs of compounds; and
FIG. 12 is a phase diagram illustrating weight percent of compound versus temperature for selected compounds of pairs of compounds;
FIG. 13 is a schematic cross-section of a liquid crystal display device containing the liquid crystal materials of the present invention.


DETAILED DESCRIPTION OF THE INVENTION

According to this invention 2,3,6,7,10,11 triphenylene discotic compounds are provided of Formula I: ##STR2## where each of Z.sub.1-6 is given by Formula II: ##STR3## where Y for each of Z.sub.1-6 is independently selected from COO, OCO, CH.sub.2 O, and OCH.sub.2, m defines the number of substituents on each of Z.sub.1-6 and is independently selected from 0-5, and X is independently selected for each substituent on each of Z.sub.1-6 from alkyl (straight chain, branched and chiral), alkoxy (straight chain, branched or chiral), alkanoyl (straight chain, branched or chiral), alkenyl (straight chain, branched or chiral), halogen, halogenoalkyl (straight chain, branched or chiral) and CN, provided that at least one of Z.sub.1-6 has at least one substituent X, and excluding where m is 1 for each of Z.sub.1-6, Y is COO for each of Z.sub.1-6 and X is n-alkyl or n-alkoxy positioned para to Y for each of Z.sub.1-6, and also where m is 5 for each of Z.sub.1-6, Y is COO for each of Z.sub.1-6 and for each Z.sub.1-6 X is selected as n-alkoxy positioned para to Y and fluorine for all other substituents.
Where substituent(s) are selected from alkyl, alkoxy, or alkenyl, then such substituents are preferably selected from C.sub.1-20.
The structural preferences discussed below are inter alia on the basis of ease of preparation and/or usefulness in liquid crystal materials.
Preferred structures for each of independently selected Z.sub.1-6 are given below: ##STR4## where X.sub.j is selected from alkyl, alkoxy, halogen (preferab

REFERENCES:
patent: 4333709 (1982-06-01), Dubor's et al.
patent: 5518783 (1996-05-01), Kanata et al.
Phillips et al., "On the Influence of Short Range Order Upon the Physical Properties of Triphenglene Nematic Discogens", Liq. Cryst. vol. 15 No. 2. pp. 203-215, 1993.
Voucher et al., Orientation of Discotic Mesophase's, Mol. Cryst. and Liq. Cryst. vol. 66. No. 1-4, pp. 103-114, 1981.
Chapuget et al., "Trimerization of Aromatic Orthediasters: New Development.", Tetrahedron, vol. 47, No. 4/5, pp. 791-798, 1991.
CA 95: 52991, 1981.
CA 100: 93661, 1984.

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