DE19510892A1 - New liq. crystalline cpds. with nematic, smectic and cholesteric phases - Google Patents

Abstract

New liq. crystalline cpds. of formula X-(Y-A-Y-M-Y-B)n (I) are claimed. In (I): X = aliphatic or aromatic alkenyl, alkynyl or cycloaliphatic gp.; n = 2, 4 or 5; Y = a direct bond, -COO-, -OCO-, -O-, -CONH- or -CON(R)-; R = 1-4C alkyl; A = a spacer; M = a mesogenic gp.; and B = a side chain.

Description

It is a large number of liquid crystalline compounds known. As a rule, however, these do not solidify glassy. Defined, glassy solidifying connections with liquid crystalline properties are e.g. B. in DE-A 37 03 640, DE-A 38 27 603, DE-A 38 30 968 and EP-A-504 660 described. Common to those in the first three registrations wrote connections that they also out of the glass state easily crystallize and thus the orientation in the frozen is not stable. Also in the case of the crystalli any mixtures used are no longer stable because Crystallize the demands on the molecules to build mix crystals is much more stringent than the requirements for Miscibility in an anisotropic fluid.

The compounds described in EP-A-504 660 form stable Glasses out. They have a high dipole moment parallel to the mole longitudinal axis and form nematic or smectic A phases. Due to the dipole moment along the molecular axis orien these materials coexist in the electric field, so that they have neither ferroelectric properties nor any helical superstructures in the electrical field are stable.

Liquid-crystalline systems are also known, the one have defined structure and in which mesogenic groups are bound to a central unit via a spacer e.g. B. DE-A-40 11 811). However, these materials do not solidify glassy, but crystallize due to their high symmetry very easy. Furthermore, in Liquid Crystals 11 (5), 779 (1992) ferroelectric liquid crystals described above a Spacers are bound to a central unit. These materials have mesogenic structures that are resistant to thermal influences as well as against weak acids or bases and against water are unstable.

Desirable for use as a liquid crystalline ferro electrical materials would be connections that have a phase behavior ten, in which the phase sequence nematic during cooling, through smectic A and smectic C. Furthermore, the Materials for verifying the pressure sensitivity of a display reduce, have high flow viscosities and above all ge be stable against weak acids and bases. Further is desired  also good miscibility with other liquid crystalline Links.

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

The invention now relates to corresponding connections of all general formula I

X (-YAYMYB) _n I,

in the
X is an aliphatic, aromatic alkenyl, alkynyl or cycloaliphatic radical
n one of the numbers 2, 4 or 5, the symbols
Y independently of one another a direct bond, -COO-, -OCO-, -O-, -CONH-, or -CON (R) - with R = C₁ to C₄ alkyl,
A a spacer,
M is a mesogenic group and
B are a side chain.

Residues X are for example:
alkylene,

or alkylene optionally interrupted by O, NH or NR; individual alkylene residues are e.g. B.

with p = 1 to 20, preferably 1 to 10. R has the level meaning.

Of the radicals Y are in particular -OCO-, -O- and -COO- before moves.

All groups known for this purpose can be used as spacers be applied; The spacers are usually via ester or Ether groups or a direct bond linked to X. The Spacers generally contain 2 to 30, preferably 2 to 12 and especially 6 to 12 carbon atoms and can in the chain, for. B. by O, D, S, NH or NCH₃ be interrupted. As a substituent for the Spacer chains come with fluorine, chlorine, bromine, cyan, methyl or ethyl.

Representative spacers are for example:

in which
m 1 to 3 and
p are 1 to 12.

The known mesogenic groups can in turn be used as residues M. be applied. In particular come aromatic or hetero radicals containing aromatic groups into consideration. The mesogenic Residues correspond in particular to formula III

(-T-Y¹) _r -T III,

in which the leftovers
independently of one another an aromatic or heteroaromatic,
Y¹ are independently O, COO, OCO, CH₂O, OCH₂, CH = N or N = CH or a direct bond and
r are 1 to 3.

R is preferably 1 or 2.

The radicals T are generally aromatic or carbocyclic heterocyclic, optionally by fluorine, chlorine, bromine, cyano, Hydroxy or nitro substituted ring systems which, for. B. following Basic structures correspond to:

Particularly preferred as mesogenic groups M z. B .:

Side chains B are, for example, C₂ to C₃₀ alkyl or -Alkenyl, preferably C₂ to C₁₁ alkyl, the radicals being linear or branched through one or more times

interrupted and by phenyl, fluorine, chlorine, bromine, Dyan or hydroxy can be substituted.

Individual residues B are z. B. C₂H₅, C₃H₇, C₄H₉, C₅H₁₁, C₆H₁₃, C₇H₁₅, C₈H₁₇, C₉H₁₉, C₁₀H₂, C₁₁H₂₃, C₁₂H₂₅,

Chiral side chains B are e.g. B .:

wherein R¹ is a C₁ to C₁₂ alkyl radical, the chiral or achiral can and R² is a radical R¹, fluorine or chlorine.

Preferred radicals R 1 are e.g. B .:

p is 1 to 12.

To prepare the compounds of formula I with the X adj beard

can you e.g. B. carboxylic acid chlorides of the formula

X (COCl) _w

with a compound of the formula

implement according to known methods. For the next to the X Beard rest Y = OCO can be compounds of the formula

X (OH) _w

with compounds of the formula

ClOC-A-Y-M-Y-B

react analogously. For Y = O the implementation of Hydroxyl with haloalkyl.

Basic manufacturing methods are known from the literature, for example, the reaction with dicyclohexylcarbodiimide (DCC) for the production of esters. Details of implementation tongues can be found in the examples in which An gave about parts and percentages, unless otherwise noted refer to the weight.

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

The compounds according to the invention take an intermediate position between low molecular weight and polymeric liquid crystalline Ver bindings. In contrast to the polymers, they are reprodu producible, have largely uniform structure and still have viscosities like the polymers.

It can be useful for setting desired properties be to use mixtures of compounds of formula I these mixtures being in situ or by mechanical mixing can be produced.

The compounds according to the invention are particularly suitable for use in displays and for producing light reflective layers.  

Examples

In the following, some are used throughout the examples Abbreviations listed:

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 became polarization micro scopically recorded. The temperature control was carried out in one Mettler microscope heating table FP80 / 82. The spontaneous polarization was carried out according to the method of Miyasato et al. Jpn. J. Appl. Phys. 22, L230 (1986).

Example 1 Production of (2-heptyl-5 [4- (8-hydraxyoctaxy) phenyl-1,3,4-thiadiazal) terephthalic acid diester

0.02 times 1,4-benzenedicarboxylic acid chloride were 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 had taken place, the mixture was concentrated 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 l.

Examples 2 to 14 were prepared analogously to Example 1.

Example 15 Production of tetra- [2-heptyl-5- [4- (hydroxyoctoxy) phenyl-1,3,4-thia diazolyl] pyromellitic acid ester 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-hydro xyoctoxy) phenyl-1,3,4-thiadiazole, dissolved in 50 ml of dimethylform amide, is added dropwise with stirring over the course of half an 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 filtered 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. It 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 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 a vacuum.
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.degree. A solution of 0.44 g (0.0011 mol) of 2-heptyl-5- [4- (8-hydroxyoxoxy) phenyl-1,3,4-thiadiazole in 50 ml of toluene and 30 ml of pyridine is added to this solution dripped. 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 (11)

1. Liquid-crystalline compounds of the general formula I X (-YAYMYB) _n I, in which
X is an aliphatic, aromatic or alkenyl alkynyl or cycloaliphatic radical,
n one of the numbers 2, 4 or 5, the symbols
Y independently of one another a direct bond, -COO-, -OCO-, -O-, -CONH-, or -CON (R) - with R = C₁ to C₄ 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 z or 4th 3. Liquid crystalline compounds of the general formula I according to claim 1 with Y being O, COO or OCO. 4. Liquid crystalline compounds of the general formula I according to claim 1 with spacers that relate to 2 to 12 carbon atoms approximately 6 to 12 included. 5. Liquid crystalline compounds of general formula I according to claim 1 with M equal to (T-Y¹) _r -T, in which the radicals
T independently of one another an aromatic or heteroaromatic,
Y¹ are independently O, COO, OCO, CH₂O, OCH₂, CH = N or N = CH or a direct bond and
r are 1 to 3. 6. Liquid-crystalline compounds of general formula I according to claim 1 with B as a C₂ to C₁₁ alkyl or alkenyl group, which are still by interrupted and substituted by phenyl, fluorine, chlorine, bromine, cyan or hydroxy. 7. Liquid crystalline compounds according to claim 5, with Y¹ equal to COO, OCO or a direct bond. 8. Liquid-crystalline compounds according to claim 6, with B as a C₃ to C₁₁ alkyl group bonded via O, COO or OCO, which can be interrupted one or more times by O. and is preferably unbranched. 9. Liquid-crystalline compounds according to claim 6, with B as a bonded via O, COO or OCO, chiral C₃- to C₁₁-alkyl group which is also substituted by fluorine, chlorine, bromine, cyano or hydroxy or by can be interrupted. 10. Liquid crystalline compounds according to claim 9, with B as a chiral C₃- bis bound via O, COO or OCO C₁₁-alkyl group, which is still fluorine, chlorine, bromine or Hydroxy substituted or interrupted by O or COO can. 11. Use of the compounds according to claims 1 to 10 alone in a mixture with each other or together with other liquids crystals in arrangements for the optical representation of Information.