EP0944577A1

EP0944577A1 - Polymerizable oligomesogenes

Info

Publication number: EP0944577A1
Application number: EP97951170A
Authority: EP
Inventors: Karl-Heinz Etzbach; Karl Siemensmeyer; Peter Schuhmacher
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1996-11-27
Filing date: 1997-11-11
Publication date: 1999-09-29
Also published as: CN1245484A; WO1998023580A1; JP2001505879A; AU5481298A; US6335462B1; CA2272103A1; DE19649056A1; KR20000057240A

Abstract

The invention relates to compounds of the general formula (I) X[-Y1-A1-Y2-M-Y3-A2-Z]n in which X is a silicon free, n-bond central unit; the radicals A1 and A2 are, independently of one another, a direct bond or a spacer; the radicals Y1, Y2 and Y3 are, independently of one another, a direct bond, O, S, CO, OCO, COO, OCOO, (a), (b), COS or SCO; M is a mesogene group; Z is a polymerizable group; n is a number between 2 and 6 inclusive; R is hydrogen or C1-C4-alkyl; and the combination of M-Y3-A2-Z can represent a cholesterol radical. These compounds are suitable as orientation layers for liquid crystal materials, as photolinkable adhesives, as monomers for the production of chirally dopable polymerizable liquid crystal systems, as matrix monomers for polymer-dispersed displays, or as a basic material for polymerizable liquid crystal materials for optical elements, like polarizers, retardation plates or lenses.

Description

Polymerizable oligomesogens

description

As is known for shape-anisotropic media, liquid-crystalline phases, so-called mesophases, can occur during heating. The individual phases differ in the spatial arrangement of the molecular centers on the one hand and in the molecular arrangement with respect to the long axes on the other hand (G.W. Gray,

P.A. Winsor, Liquid Crystals and Plastic Crystals, Ellis Horwood Limited, Chichester 1974). The nematic liquid-crystalline phase is characterized by the fact that only one long-range orientation order exists through parallel storage of the longitudinal axes of the molecules. Provided that the molecules that make up the nematic phase are chiral, a so-called cholesteric phase is created in which the long axes of the molecules form a helical superstructure perpendicular to them (H. Baessler, Solid State Problems 2 - 1971). The chiral part of the molecule can either be present in the liquid-crystalline molecule itself or be added to the nematic phase as a dopant, the cholesteric phase being induced. This phenomenon was first investigated on cholesterol derivatives (e.g. H. Baessler, MM Labes, J. Chem. Phys., Ü, 631 (1970); H. Baessler, TM Laronge, MM Labes, J. Chem. Phys., 51 799 ( 1969); H. Finkelmann,

H. Stegemeyer, Z. Naturforschg. 28a, 799 (1973); H. Stegemeyer, K.J. Mainusch, Naturwiss., .5_8_, 599 (1971), H. Finkelmann, H. Stegemeyer, Ber. Bunsenges. Phys. Chem. 2 £, 869 (1974)).

The cholesteric phase has remarkable optical properties: high optical rotation as well as a pronounced circular dichroism, which is created by selective reflection of circularly polarized light within the cholesteric layer. The colors, which appear different depending on the point of view, depend on the pitch of the helical superstructure, which in turn depends on the ability of the chiral component to twist. In particular, by changing the concentration of a chiral dopant, the pitch and thus the wavelength range of the selectively reflected light of a cholesteric layer can be varied. Such cholesteric systems offer interesting possibilities for practical use. By incorporating chiral molecular parts into mesogenic acrylic acid esters and orienting them in the cholesteric phase, e.g. after photocrosslinking, a stable, colored network can be produced, the concentration of chiral components of which can then no longer be changed (G. Galli, M. Laus, A. Angelon, Makromol. Chemie, 187, 289 (1986)). By Mixing non-crosslinkable chiral compounds into nematic acrylic acid esters can be produced by photocrosslinking, which still contains high proportions of soluble components (I. Heyndricks, DJ Broer, Mol. Cryst. Liq. Cryst. 203, 113 (1991)). Furthermore, by statistical hydrosilylation of mixtures of cholesterol derivatives and acrylate-containing mesogens with defined cyclic siloxanes and subsequent photopolymerization, a cholesteric network can be obtained in which the chiral component can have a share of up to 50% of the material used; however, these polymers still contain significant amounts of soluble components (FH Kreuzer, R. Maurer, Ch. Muller-Rees, J. Stohrer, Lecture No. 7, 22nd Freiburger Arbeitstagung Flussigkristalle, Freiburg, 1993).

The application DE-OS-35 35 547 describes a method in which a mixture of cholesterol-containing monoacrylates can be processed into cholesteric layers by means of photo-crosslinking. However, the total proportion of the chiral component in the mixture is approximately 94%. As a pure side chain polymer, such a material is not mechanically very stable, but an increase in stability can be achieved by highly crosslinking diluents.

In addition to the nematic and cholesteric networks described above, smectic networks are also known, which are produced in particular by photopolymerization / photocrosslinking of smectically liquid-crystalline materials in the smectically liquid-crystalline phase. The materials used for this are generally symmetrical, liquid-crystalline bisacrylates such as those used by DJ Broer and RAM Hikmet, Makromol. Chem., 19_Q_, 3201-3215 (1989). However, these materials have very high clear temperatures of> 120 ° C., so that there is a risk of thermal polymerization. By adding chiral materials, piezoelectric properties can be achieved in the presence of an S _c phase (RAM Hikmet, Macromolecules 25, p. 5759, 1992).

The invention now relates to structures of general formula I.

X [_Y ₁ _A ₁ -Y ₂ -MY ₃ -A ₂ -Z] _n I,

in the

X is a silicon-free, n-bonded central unit, the residues Ai and A independently of one another a direct bond or a spacer, the residues

Yi, Y ₂ and Y ₃ independently of one another a direct bond, 0, S, CO, OCO, COO, OCOO,

CON _f N-CO, COS or SCO,

R 'R

M a mesogenic group,

Z is a polymerizable group and

n is a number from 2 to 6, where

R is hydrogen or C 1 -C ₄ alkyl and the combination of M-Y ₃ -A-Z may represent a cholesterol residue.

X radicals can be aliphatic, aromatic or cycloaliphatic and also contain heteroatoms. In addition, double-bonded elements and groups such as 0, S, S0 ₂ or CO come into consideration.

For X are in particular C to C alkylene, alkenylene or alkynylene radicals, which can be interrupted one or more times by 0, S or NR, phenylene, benzylene or cyclohexylene and radicals of the formulas

to call.

Individual alkylene, alkenylene or alkynylene radicals are, for example - (CH ₂ ) _p -, (CH ₂ CH2θ) _q CH2CH ₂

CH ₃ CH ₃

CH-CH ₂ 0 / CH-CH ₂ CH ₂ CHCHCHCHCH ₂ q

CH ₂ CHCHCHCH ₂ , CH = CH or

in which

p the numbers 2 to 12,

q the numbers 1 to 3 and

r represent the numbers 1 to 6.

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 0, 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 -, - (CH ₂ CH2θ) _q CH ₂ CH2-, -CH ₂ CH ₂ SCH ₂ CH ₂ -, -CH ₂ CH ₂ NHCH ₂ CH ₂ -, CH3 CH ₃ CH ₃ CH ₃ Cl

> I I I I

-CH ₂ CH ₂ N — CH ₂ CH ₂ - '- (CH ₂ CHO) _q CH ₂ CH-' - (CH ₂ ) ₆ CH- or -CHCH ₂ CH- '

where p and q have the meaning given.

For Y _{1 (} Y ₂ and Y ₃ a direct bond, O, OCO, COO and OCOO are preferred. The known mesogenic groups can in turn be used as residues M. In particular, radicals containing aromatic or heteroaromatic groups are suitable. The mesogenic residues correspond in particular to formula II

(-TY ¹ ) II,

in which the leftovers

T independently of one another cycloalkylene or heterocycloalkylene radical, an aromatic or heteroaromatic,

Y ^{1 is} independently O, COO, OCO, CH ₂ 0, OCH ₂ , CH = N or N = CH or a direct bond and

s are 1 to 3.

Preferably s is 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, for example

11

Preferred groups Z are those which can be polymerized by a photochemical initiation step, in particular groups of the structure: CH ₂ = CH-, CH ₂ = CC1, CH ₂ = C (CH ₃ ) - or 4-vinylphenylyl. CH ₂ = CH-, CH ₂ = CC1- and CH ₂ = C (CH ₃ ) - are preferred, with CH = CH- and CH = C (CH ₃ ) - being particularly preferred.

Basic production methods for the compounds of the formula I 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, relates 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 set desired properties, it may be expedient to use mixtures of compounds of the formula I or mixtures with other liquids, it being possible for these mixtures to be prepared in situ or by mechanical mixing.

The compounds according to the invention are particularly suitable as orientation layers for liquid-crystalline materials, as photo-crosslinkable adhesives, as monomers for the production of liquid-crystalline networks, as base material for the production of chirally dopable polymerizable liquid-crystal systems, as polymerizable matrix monomers for polymer-dispersed displays or as base material for polymerizable, liquid-crystalline materials for optical components, such as polarizers, retardation plates or lenses. They are furthermore suitable as film formers in combination with low molecular weight, polymerizable liquid crystalline compounds.

The melting temperatures in the example section were recorded using polarization microscopy. The temperature was checked in a Mettler microscope heating table FP80 / 82.

Examples

0

I, II and III are mesogens, IV and V are central units. example 1

1 ml of a solution of 13.6 g (0.05 g) is added to a solution of 0.903 g (0.0015 mol) I, 0.846 g (0.0015 mol) II and 0.32 g pyπdin in 30 ml toluene at 60 ° 05 mol) 1, 3, 5-cyclohexane tricarboxylic acid chloride in 50 ml of absolute toluene. The solution is stirred at 60 ° C for one hour. After stirring overnight at room temperature, 50 ml of water are added and it is neutralized with 15% hydrochloric acid. The organic phase is separated off, washed with water, then dried with sodium sulfate and concentrated. Further purification is carried out by column chromatography (silica gel 60, toluene / ethyl acetate 3: 1).

Yield: 1.45 g phase behavior: n ^* polymerized

The compounds in the following table were prepared analogously to Example 1:

x means unidentified phase G means glass state s means smectic phase n or n ^* means: nematic or chiral-nematic phase i means: isotropic phase K means: crystalline

All of the above compounds are converted into polymers at elevated temperature. Example 9

0.66 g (0.03 mol) of benzene-1, 2, 4, 5-tetracarboxylic acid anhydride and 3.8 g of II are suspended in 15 ml of DMF and stirred at 110 ° C. for 8 hours. The reaction product is precipitated by pouring it into water, suction filtered, washed with water and dried at 50 ° C. in vacuo. It is then recrystallized from ethanol / toluene.

Yield: 2.7 g fixed point: 170-215 ° C.

1.49 g (0.001 mol) of the reaction product thus obtained, 1.2 g (0.002 mol) I and 0.03 g (0.00022 mol) pyrrolidinopyridine are dissolved in 40 ml methylene chloride. 0.45 g (0.0022 mol) of dicyclohexylcarbodiimide are then added at 15 ° C. and the mixture is stirred at room temperature overnight. The solution is filtered off, concentrated and the precipitated residue is chromatographed over silica gel 60 with toluene / glacial acetic acid 3: 1.

Yield: 1 g phase behavior: x 46-70 n ^* 160-180 i

Example 10

The isomeric compounds in which benzene-1, 2, 4, 5-tetracarboxylic acid anhydride was esterified first with III and then with I were prepared analogously to Example 9.

Yield: 500 mg phase behavior: K 61-70 n ^* 168-186 i

Example 11

Production of

114 g (0.5 mol) of 4-benzyloxybenzoic acid chloride are dissolved in a mixture of 150 ml of absolute CHC1 ₂ and 9.6 g of pyridine. Then 7.3 g (0.55 mol) of 1,8-octanediol are introduced at 10 to 15 ° C. and the mixture is stirred overnight. The reaction product is precipitated by pouring it into water and recrystallized from 250 ml of ethanol. Yield: 25.1 g (= 88.7% of theory). Melting point: 90-91 ° C

24.9 g (0.044 mol) of the reaction product are dissolved in a mixture of 150 ml of toluene and 100 ml of ethanol, and 5.1 g of Raney nickel are added. The mixture is then hydrogenated at 45 to 50 ° C. for 1.5 h with vigorous stirring. The H ₂ uptake was 2.1 l under normal pressure. The reaction product is separated from the contact and filtered off. No further cleaning was necessary.

Yield: 16.8 g (= 98.9% of theory) Melting point: 182-183 ° C

0.97 g (0.0025 mol) of the compound thus obtained, 0.1 g of pyrrolidinopyridine and 1.53 g of the compound of the formula

are dissolved in 50 ml of tetrahydrofuran. A solution of 1.5 g of dicyclohexylcarbodiimide in 5 ml of tetrahydrofuran is then added at 5 to 10 ° C. and the mixture is stirred at 50 ° C. for 4 h and then at room temperature overnight. Precipitated solid is filtered off and the solution is concentrated. The residue is purified by column chromatography (silica gel 60 / toluene-glacial acetic acid 3: 1).

Yield: 0.45 g phase behavior: K 77-82 n polymerized

The following connections can be made analogously:

Example 12

Phase behavior: K 116-144 n 154-156 i Example 13

Phase behavior: K 148 n 185 i

The following compounds can also be prepared analogously to Example 1:

Example 14

0

Phase behavior: K 86 n -> polymerized

Example 15

Phase behavior: K 100 n - polymerized Example 16

4.2 g (0.02 mol) of the compound of the formula

HO 0 (CH ₂ ) OH

are dissolved in 50 ml of tetrahyderofuran and 1.58 ml of pyridine. 6.77 g (0.04 mol) of the compound of the formula are added to this solution

given and it is stirred overnight. The reaction mixture is poured into water acidified with HC1 and the solid is filtered off. The solid is taken up in methyl tert-butyl ether and the organic phase thus obtained is shaken out several times with water. The solid obtained after the concentration is recrystallized from ethanol / toluene.

Yield: 3.45 g

Phase behavior: K 133 n → polymerized

Example 17

60.4 g (0.4 mol) of methyl hydroxybenzoate and 2.6 g (0.02 mol) of zinc (II) chloride are suspended in 180 ml of methylene chloride. After stirring for 20 minutes at room temperature, 16.2 g (0.2 mol) of disulfur dichloride dissolved in 20 ml of methylene chloride are added over the course of 2 hours at room temperature, then the mixture is heated under reflux for 1 1/2 hours and at room temperature for 48 hours. stirs. The reaction product is filtered off and washed with methylene chloride, then taken up in water and boiled for 1 h. After cooling, the product is filtered off and dried.

Yield: 11.8 g Melting point: 170-172 ° C

5.01 g (0.015 mol) of the compound thus prepared are dissolved in 50 ml of methylene chloride and 2.61 g (0.033 mol) of pyridine. 10.65 g (0.033 mol) of the compound of the formula are added to this solution

dissolved in 20 ml of methylene chloride, then stirred overnight at room temperature. For working up, the reaction mixture is poured into water, the precipitated solid is filtered off with suction and purified by chromatography (silica gel 60; toluene / THF 3: 1)

Yield: 9.45 g K 159 -> polymerized

The connection corresponds to the formula

0

/ T -0 "- (-CH ₂ ) -O 4-o ^~ - -C00CH3

Example 1 <

Analogously to Example 17, the compound of the formula

manufactured. It polymerizes when heated.

Example 19

COOCH ₃

4.34 g (0.015 mol) of the compound of the formula

are dissolved in 40 ml of glacial acetic acid and 3.24 g (0.0286 mol) of perhydrol (30% in water) are added at room temperature. Then the mixture is stirred at 100 ° C. for 1 h. After cooling, the product is poured into water, suction filtered, washed several times with water and dried in vacuo at 50 ° C.

Yield: 4.5 g melting point 210-221 ° C

Upon further reaction of the compound thus obtained analogously to Example 17, the above is obtained.

Yield: 2.75 g

K 199 polymerizes during the transition to the liquid crystalline phase.

Claims

claims

1. Compounds of the general formula I

X [_γ ₁ _A ₁ -Y ₂ -MY ₃ -A ₂ -Z] _n I,

in the

X is a silicon-free, n-bonded central unit, the residues

Ai and A ₂ independently of one another a direct bond or a

Spacer, the leftovers

Yi, Y ₂ and Y ₃ independently of one another a direct bond, 0, S, CO,

OCO, COO, OCOO,

CON _r N-CO, COS or SCO,

R R

M a mesogenic group,

Z is a polymerizable group and

n is a number from 2 to 6, where

R is hydrogen or C 1 -C ₄ alkyl and the combination of M-Y ₃ -A ₂ -Z may represent a cholesterol residue.

2. Compounds according to claim 1, in which

X is an aliphatic, aromatic or cycloaliphatic radical or 0, S, S0 ₂ or CO.

3. Compounds according to claim 1, in which M is a radical of the formula

(-TY ¹ ) _s -τ

is where the leftovers

T independently of one another an aromatic or heteroaromatic, Y ^{1 is} independently O, COO, OCO, CH ₂ 0, OCH ₂ , CH = N or N = CH or a direct bond and

s are 1 to 3.

4. Compounds according to claim 1, in which Z is a radical of the formula

CH ₂ = CH, CH ₂ = CC1 or CH ₂ = C (CH ₃ ;

is.

5. Use of the compounds according to claim 1 as orientation layers for liquid-crystalline materials, as photocrosslinkable adhesives, as monomers for the production of liquid-crystalline networks, as the base material for the production of chirally doped polymerizable liquid crystal systems, as the polymerizable matrix monomers for polymer-dispersed displays or as the base material for polymerizable, liquid-crystalline materials for optical components, such as polarizers, delay plates or lenses or in combination with low-molecular, polymerizable liquid-crystalline compounds as film formers.