WO1996030352A1 - Liquid crystal compounds - Google Patents

Abstract

The invention concerns liquid crystal compounds of general formula (I) X(-Y-A-Y-M-Y-B)n in which X is an n-valent aliphatic, aromatic or cycloaliphatic group or an n-valent alkenyl or alkinyl group; n is one of the numbers 2, 4 or 5, the symbols Y, independently of one another, designate a direct bond, -COO-, -OCO-, -O-, -CONH- or -CON(R)- with R = C1 to C4 alkyl, A designates a spacer, M designates a mesogenic group and B is a side chain. The compounds according to the invention are particularly suitable for data display.

Description

Liquid crystalline compounds

description

A large number of liquid-crystalline compounds are known. As a rule, however, these do not solidify glassy. Defined, glass-like solidifying compounds with liquid crystalline properties are e.g. described in DE-A 37 03 640, DE-A 38 27 603, DE-A 38 30 968 and EP-A-504 660. Common to the compounds described in the first three applications is that they also crystallize easily from the glass state and thus the orientation in the frozen state is not stable. Also, in the case of crystallization, any mixtures that are used are no longer stable, since in the crystal the requirements for the molecules to form mixed crystals are much more stringent than the requirements for miscibility in an anisotropic fluid.

The compounds described in EP-A-504 660 form stable glasses. They have a high dipole moment parallel to the longitudinal axis of the molecule and form nematic or smectic A phases. Because of the dipole moment along the longitudinal axis of the molecule, these materials orient themselves in parallel in the electric field, so that they have neither ferroelectric properties nor any helical superstructures that are present are stable in the electric field.

Liquid-crystalline systems are also known which have a defined structure and in which mesogenic groups are bonded to a central unit via a spacer (e.g. DE-A-40 11 811). However, these materials do not solidify glassy, but crystallize very easily due to their high symmetry. Furthermore, Liquid Crystals ___________________, 779 (1992) describes ferroelectric liquid crystals which are bound to a central unit via a spacer. These materials have mesogenic structures that are unstable against thermal influences as well as against weak acids or bases and against water.

Compounds which have a phase behavior in which the phase sequence is passed through nematic, smectic A and smectic C during cooling would be desirable for use as liquid-crystalline ferroelectric materials. In addition, in order to reduce the pressure sensitivity of a display, the materials should have high flow viscosities and, above all, be stable against weak acids and bases. What is desired is- also good miscibility with other liquid-crystalline compounds.

The object of the present invention is therefore to provide new, liquid-crystalline, glass-like solidifying compounds which have smectic and nematic phases, are insensitive to temperature and pH fluctuations and to water and have a high flow viscosity.

The invention now relates to corresponding compounds of the general formula I.

X (-YAYMYB) _n I,

in the

X is an n-valent aliphatic, aromatic or cycloaliphatic radical or an n-valent alkenyl or alkynyl radical

n one of the numbers 2, 4 or 5, the symbols

Y independently of one another is a direct bond, -COO-, -OCO-, -O-, -CONH- or -CON (R) - with R = Ci to C ₄ alkyl,

A a spacer,

M is a mesogenic group and

B are a side chain.

X are, for example: alkylene,

oder gegebenenfalls durch O, NH oder NR unterbrochenes Alkylen; einzelne Alkylenreste sind z.B. - ( CH₂ ) _D- , -CH-CH₂- . -CH₂OCH₂ - , -CH₂NHCH₂ - oder -CH N — CH₂ -

or optionally alkylene interrupted by O, NH or NR; individual alkylene radicals are, for example - (CH ₂ ) _D -, -CH-CH ₂ -. -CH ₂ OCH ₂ -, -CH ₂ NHCH ₂ - or -CH N - CH ₂ -

I I

CH3 CH ₃

where p = 1 to 20, preferably 1 to 10. R has the meaning given.

n is preferably 2 or 4.

Of the radicals Y, in particular -OCO-, -0- and -COO- are preferred.

All groups known for this purpose can be used as spacers; The spacers are usually linked to X via ester or ether groups or a direct bond. The spacers generally contain 2 to 30, preferably 2 to 12 and in particular 6 to 12 C atoms and can be interrupted in the chain, for example by O, S, NH or NCH ₃ . Fluorine, chlorine, bromine, cyano, methyl or ethyl are also suitable as substituents for the spacer chain.

Representative spacers are for example:

(-CH ₂ ) _P -, - (CH2CH2θ) _m CH2CH2-, -CH ₂ CH ₂ SCH ₂ CH2-, -CH2CH2NHCH2CH2-,

^CH 3 CH ₃ CH ₃ CH ₃ Cl

-CH ₂ CH ₂ N-CH ₂ CH ₂ - '- (CH ₂ CHO) _m CH ₂ CH-' - (CH ₂ ) ₆ CH- or -CH ₂ CH ₂ CH- where m is 1 to 3 and p 1 to Are 12.

The known mesogenic groups can in turn be used as residues M. Aromatic or heteroaromatic groups containing radicals are particularly suitable. The mesogenic residues correspond in particular to the formula III

(-T-Y r-T III,

in which the leftovers

T independently of one another an aromatic or heteroaromatic,

Y ¹ independently of one another -O-, -COO-, -OCO-, -CH ₂ O-, -OCH ₂ -, -CH = N- or -N = CH- or a direct bond and r are 1 to 3.

R is preferably 1 or 2.

Y ¹ is preferably -COO-, -OCO- or a direct bond.

The radicals T are generally aromatic carbocyclic or heterocyclic ring systems optionally substituted by fluorine, chlorine, bromine, cyano, hydroxyl or nitro, which e.g. correspond to the following basic structures:

Particularly preferred as mesogenic groups M are e.g.

Side chains B are, for example, C - to C ₃ o-alkyl or alkenyl, preferably C - to Cn-alkyl or alkenyl, the radicals being linear or branched, one or more times by -0-, -OCO-, -CO- O, -CH— CH - / -NH- or -N (CH ₃ ) - interrupted and by

\ /

0 Phenyl, fluorine, chlorine, bromine, cyan or hydroxy may be substituted.

B is particularly preferably a C ₃ - to C 11 -alkyl group which is bonded via -O-, -COO- or -OCO- and which can be interrupted one or more times by oxygen and is preferably unbranched.

Individual radicals B are, for example, -C ₂ H ₅ , -C ₃ H, -C Hg, -C ₅ H ₁₁ , -C ₆ H ₁₃ , -C ₇ H ₁₅ , -C _Θ H ₁₇ , -C9H19, -C10H21, -C11H23. - 12H25-

-CH₂CH = CH₂ , - ( CH₂ ) 7CH = CH₂ oder - ( CH₂ ) ₈CH CH₂.-CH tri. _Λ decy, l,

-CH ₂ CH = CH ₂ , - (CH ₂ ) 7CH = CH ₂ or - (CH ₂ ) ₈ CH CH ₂ .

Further preferred side chains B are chiral C ₃ -Cn-alkyl groups bonded via -0-, -COO- or -OCO- which are also substituted by fluorine, chlorine, bromine, cyano or hydroxyl or by

0

/ \

-O-, -COO-, -OCO- or -CH— CH— can be interrupted, in consideration.

Chiral side chains B are e.g. B.: Cl CH C ₆ Hi 3 'CH ₂ - - CH - - C ₂ H ₅

CH R ¹

*

CH ₃ CH ₃

OH CH ₃

CH ₂ CH R ¹ / CH - - 0 - ^■ Rl

* *

CH3 0 ^H 3 CIHI CI 0 R ¹ - CH ₂ C 1H OR ¹ or

0

wobei R¹ ein Ci- bis Ci₂-Alkylres , der chiral oder achiral sein kann und R² ein Rest R¹, Fluor oder Chlor sind.

wherein R ^{1 is} a Ci to Ci ₂ alkylres, which can be chiral or achiral and R ^{2 is} a radical R ¹ , fluorine or chlorine.

Preferred radicals R ¹ are, for example:

* * *

-C _p H _{2p +} ι, -CH-C ₂ H5 '-CHCH3> -CH-C ₆ Hi3 or -CH ₂ -CHC ₂ H ₅ ' IIII

CH ₃ CH ₃ CH ₃ CH ₃

p is 1 to 12.

For the preparation of the compounds of formula I in which the bridge member Y adjacent to X is -COO-, -CONH- or -CONR-, e.g. Carboxylic acid chlorides of the formula

X (COCl ⁾ _n

with a compound of the formula

HO-AYMYB, H ₂ NAYMYB or HN-AYMYB

Implement R using known methods. If the radical Y adjacent to X is a bridge member -OCO-, compounds of the formula can be used X (OH) _n

with compounds of the formula

react analogously. If this bridge member Y is oxygen, the reaction of hydroxyl with haloalkyl is appropriate.

Basic production methods are known from the literature, for example the reaction with dicyclohexylcarbodiimide (DCC) for the preparation of esters. Details of the implementations can be found in the examples, in which information on parts and percentages, unless stated otherwise, relate to the weight.

The compounds of the formula I are liquid-crystalline and, depending on the structure, can form smectic, nematic or cholesteric phases. They are suitable for all purposes in which liquid-crystalline compounds are usually used.

The compounds according to the invention occupy an intermediate position between low-molecular and polymeric liquid-crystalline compounds. In contrast to the polymers, they can be produced reproducibly, have largely uniform structures and nevertheless have viscosities like the polymers.

To achieve desired properties, it may be expedient to use mixtures of compounds of the formula I, these mixtures in situ, i.e. can be produced in the synthesis, or by mechanical mixing.

The compounds according to the invention can be used alone, in a mixture with one another or together with other liquid crystals in arrangements for the optical display of information. They are particularly suitable for use in displays and for the production of light-reflecting layers. Examples

The following are some of the abbreviations used throughout the examples:

K crystalline phase I isotropic phase

S _c Smectic C phase with ferroelectric arrangement of the mesogens S _a Smectic A phase

* Liquid-crystalline phases marked in this way are chiral Z Central unit, consists of the residues X and Y S unspecified smectic phase

The phase transition temperatures were recorded polarization microscopically. The temperature was checked in a Mettler microscope heating table FP80 / 82. The spontaneous polarization was determined according to the method of Miyasato et al. Jpn. J. Appl. Phys. 22, L230 (1986).

Example 1:

Production of

(2-heptyl-5 [4- (8-hydroxyoctoxy) phenyl-1,3,4-thiadiazole) terephthalic acid diester

0.02 mol of 1,4-benzenedicarboxylic acid chloride was dissolved in 150 ml of toluene and heated to boiling. A solution of 0.022 mol of 2-heptyl-5- [4-8-hydroxyoctoxy) phenyl-1,3,4-thiadiazole, dissolved in a mixture of 50 ml of toluene and 0.2 mol of pyridine, was then added dropwise over the course of one hour . After the reaction, the mixture was evaporated to dryness and purified by column chromatography (silica gel, toluene / ethyl acetate: 3/1). The mixture was then recrystallized from toluene / ethanol.

Yield: 13.2 g, 70% phase behavior: K 117 1

Examples 2 to 14 were prepared analogously to Example 1. If mixtures are specified in the table for the grouping (-AYMYB), corresponding molar mixtures of the compounds HO-AYMYB were used in the synthesis, statistical mixtures of the compounds I resulting.

Beispiel 15

Example 15

Production of

tetra- [2-heptyl-5- [4- (hydroxyoctoxy) phenyl-1, 3, 4 thia-diazolyl] pyro ellitic acid ester

C ₇ H ₁₅ ^

a) Reaction of pyremellitic anhydride with 2-heptyl-5- [4- (8-hydroxyoctoxy) phenyl-1,3,4-thiadiazole

21.8 g (0.1 mol) of pyremellitic anhydride are dissolved in 150 ml of dimethylformamide and heated to 110 ° C. A solution of 84.8 g (0.21 mol) of 2-heptyl-5- [4- (8-hydroxyoxyctoxy) phenyl-1,3,4-thiadiazole, dissolved in 50 ml of dimethylformamide, is dissolved in half with stirring Dripped hour. The mixture is stirred at 110 ° C for a further two hours. The reaction mixture is then carefully precipitated with water while stirring. The reaction product is suctioned off and taken up in saturated sodium carbonate solution. Undissolved components are filtered off. The reaction product is then precipitated with dilute HCl, suction filtered and washed with ethanol. The mixture is then recrystallized from toluene / ethanol.

Yield: 66.7 g (65%)

b) reaction of the reaction product from 15 a with thionyl chloride

To prepare the bis acid chloride, 51.3 g (0.05 mol) of the reaction product from 15 a were mixed with 100 ml of thionyl chloride and stirred at 50 ° C. for three hours. After completion of the gas development, the thionyl chloride was removed in vacuo and the solid was washed with petroleum ether. The acid chloride was then dried at 40 ° C. in vacuo.

Yield: 50.5 g (95%) c) Preparation of the title compound

0.53 g (0.0005 mol) of the acid chloride are dispersed in 50 ml of absolute toluene and heated to 40 ° C. A solution of 0.44 g (0.0011 mol) of 2-heptyl-5- [4- (8-hydroxyoxoxy) phenyl-1,3,4,4-thiadiazole in 50 ml of toluene and 30 ml is added to this solution Dropped pyridine. The reaction is followed by thin layer chromatography. After the reaction has ended, the mixture is precipitated in water and the reaction mixture is purified by column chromatography (silica gel 60, toluene / ethyl acetate: 4: 1).

Yield: 0.57 g (64%)

Phase behavior: S _a 87 I (no crystallization up to room temperature).

The following connections were made analogously:

Claims

claims 1. Liquid crystalline compounds of the general formula I X (-Y-A-Y-M-Y-B> n I, in the X is an n-valent aliphatic, aromatic or cycloaliphatic radical or an n-valent alkenyl or alkynyl radical, n one of the numbers 2, 4 or 5, the symbols Y independently of one another is a direct bond, -COO-, -OCO-, -0-, -CONH- or -CON (R) - with R = Ci to C ₄ alkyl, A a spacer, M is a mesogenic group and B are a side chain. 2. Liquid-crystalline compounds of the general formula I according to claim 1 with n equal to 2 or 4. 3. Liquid-crystalline compounds of the general formula I according to claim 1 with Y equal to -0-, -COO- or -OCO-. 4. Liquid crystalline compounds of general formula I according to claim 1 with spacers containing 2 to 12 carbon atoms. 5. Liquid crystalline compounds of the general formula I according to claim 1 with M being the same

being the leftovers T independently of one another an aromatic or heteroaromatic, Y ¹ independently of one another -0-, -COO-, -OCO-, -CH ₂ 0-, -OCH ₂ -, -CH = N- or -N = CH- or a direct bond and 1 to 3 are. 6. Liquid crystal compounds according to general formula I. Claim 1 with B as C - to Cn-alkyl or alkenyl group, 0 / \ which are still interrupted by -0-, -OCO-, -COO-, -CH-CH-, -NH- or -N (CH ₃ ) - and substituted by phenyl, fluorine, chlorine, bromine, cyano or hydroxy can. 7. Liquid-crystalline compounds according to claim 5, with Y ¹ being -COO-, -OCO- or a direct bond. 8. Liquid-crystalline compounds according to claim 6, with B as a via -0-, -COO- or -OCO- bound C ₃ - to Cn-alkyl group, which can be interrupted one or more times by oxygen and preferably is unbranched. 9. Liquid crystalline compounds according to claim 6, with B as a via -0-, -COO- or -OCO- bound, chiral C ₃ - bis Cn-alkyl group, which is still fluorine, chlorine, bromine, or cyan 0 / \ Hydroxy can be substituted or interrupted by 0, COO, OCO or CH-CH. 10. Liquid-crystalline compounds according to Claim 9, with B as a chiral C ₃ - to Cn-alkyl group bonded via O, COO or OCO, which can also be substituted by fluorine, chlorine, bromine or hydroxyl or interrupted by O or COO. 11. Use of the compounds according to claims 1 to 10 alone, in a mixture with one another or together with other liquid crystals in arrangements for the optical display of information.