WO1994013660A1 - Chiral, stabilised complex ligands and macrocycles and their use in liquid crystal displays - Google Patents

Abstract

The amount of chiral doping substances in FLC mixtures may be reduced by introducing chiral complex ligands and macrocycles into the FLC mixture or on the orientation layer.

Description

description

Chiral, stabilized complex ligands and macrocycles and their use in liquid crystal displays

Switching and display devices which contain ferroelectric liquid crystal mixtures (FLC displays) are known, for example, from EP-B 0 032 362 (= US 4,367,924). Liquid crystal displays are devices which e.g. change their optical transmission properties due to electrical shading in such a way that light that falls through (and possibly is reflected again) is intensity-modulated. Examples are the well-known clock and calculator displays or liquid crystal displays in the OC (office automation) or TV (television) area (see also Liquid Crystal Device Handbook, Nikkaπ Kogyo Shimbun, Tokyo, 1989; ISBN 4-526-02590-9C 3054 and works cited therein).

These FLC displays are constructed in such a way that a liquid crystal layer is enclosed on both sides by layers which, starting from the FLC layer, are usually at least one orientation layer, electrodes and a boundary plate (e.g. made of glass). They also contain a polarizer if they are operated in the "guest-host" or reflective mode, or two polarizers if the mode used is transmissive birefringence ("birefringence mode"). The switching and display elements can optionally further auxiliary layers, such as Diffusion barrier or insulation layers included.

The orientation layers, which consist of an organic (eg polyimide, polyamide and polyvinyl alcohol) or inorganic (eg SiO) material, bring together with a sufficiently small spacing Boundary disks, the FLC molecules of the mixture in a configuration in which the molecules are parallel to one another with their longitudinal axes and the smectic planes are arranged perpendicular or obliquely to the orientation layer. In this arrangement, the molecules are known to have two equivalent orientations between which they can be switched by applying an electrical field in a pulsed manner, ie FLC displays can be switched bistably. The switching times are inversely proportional to the spontaneous polarization of the FLC mixture and are in the range of μs.

The main advantage of the FLC displays compared to the LC displays that have so far been found in industrial practice is the multiplex ratio that can be achieved, i.e. the maximum number of lines that can be controlled in the time-sequential method (“multiplex method”), which is practically unlimited in the case of FLC displays, in contrast to LC displays. This electrical control is essentially based on the pulse addressing mentioned above and described by way of example in SID 85 DIGEST p. 131 (1985).

For the practical use of ferroelectric liquid crystals in electro-optical displays, chiral, inclined-smectic phases, such as S _c ^* phases, are required [RB Meyer, L. Liebert, L Strzelecki and P. Keller, J. Physique 36, L-69 ( 1975)], which are stable over a wide temperature range. This goal can be achieved with compounds which themselves form such phases, for example S _c ^* phases, or else by doping compounds which do not form chiral, inclined-smectic phases with optically active compounds [M. Brunet, CI. Williams, Ann. Phys. 3, 237 (1978)].

One of the important functional variables of an FLC display is the image build-up speed. The image build-up speed or the frame rate is given by the number of lines of an FLC display and the duration of the electrical switching pulses. The smaller the value of the Switching pulse width, the faster the image build-up. On the other hand, the switching time on the material side depends on the spontaneous polarization (P) and the viscosity (r) of the FLC material.

T «=

P _* ^» E

Since the values of the rotational viscosity (y) cannot be reduced sufficiently, increasing P _{s is} a suitable means of reducing the switching time. This can be done, for example, by increasing the FLC mixture content of optically active dopant. As a rule, the pitch is changed in the nematic π and / or smectic C phase in such a way that further dopants which produce a different helix must be added to compensate for the pitch. However, this can have adverse effects for other relevant parameters of an FLC mixture, for example the mesophase range or the rotational viscosity.

Ionic impurities make it necessary to inscribe a picture several times. so that the previously registered picture disappears completely ("ghost picture"). However, this effect, which strongly opposes the economic potential of the FLC displays, is more pronounced the higher the spontaneous polarization of the FLC material (compare, for example, B.J. Dijon et al., SID Conference, San Diego 1988, pages 2 -249).

DE-A-3 939 697 and DE-A-4 100 893 have already described the use of ligands and macrocycles to avoid or reduce the ghosting effect.

Surprisingly, it has now been found that the use of chiral ligands and macrocycles of the formula (I) enables FLC mixtures to be formulated which have no downshift effects at high values for P _s and which do not affect the pitch Compensation in the nematic and / or smectic C phase require smaller amounts of other active components.

Because two different effects - suppression of the downshift effect and at least partial pitch compensation - are achieved with one and the same mixture component, the problems mentioned above can be solved.

The invention thus relates to the compound of the general formula I.

X

I.

A [- (CH ₂ ) _m - Z - (CH ₂ ) _n -] BI

I.

R ²

I.

Y

in the Z the same or different the group

0 0 0 0 0 left || II I! I!

-O-, -S-. -S-, -S-0-, -S-N-, -S-, -S-N-, -N-, -N-0-

II II | l o o

-N-0-, 0-N-O-, -Si-, -C-, -P-, -P-0-, -P-N-,

I I I I I I I I o o

bedeutet, wobei diese mit den Gruppen -(CH₂)_q-0-, -(CH₂)_q-S-, -(CH₂) -N-,-Si-O-, -O-Si-0-, - 0-, or phenyl or pyridyl

means, with the groups - (CH ₂ ) _q -0-, - (CH ₂ ) _q -S-, - (CH ₂ ) -N-,

O 0 0 0 0

- (CH ₂ ) _q -Si-, - (CH ₂ ) _q ) -CN-, - (CH ₂ ) _q -NC-, - (CH ₂ ) _q -C-0-, - (CH ₂ ) _q - 0-C-, - (CH ₂ ) _q -C- can be substituted in the ortho, meta or para position, R ¹ and R ² are the same or different, a pair of electrons, - H or a straight-chain or branched chiral or achiral

Alkylene chain with 1 to 20 carbon atoms, in which one or more CH ₂ groups can be replaced by

F Br Cl CN O R

I I I I II I

-O-, -S-, -C-, -N-, -C, -C-, -C-, -C-, -C-, -N-, -N-S-, -Si,

II I II III II IORS S0 ₂ RO R '

-Cycloalkanediyl with 3 to 8 carbon atoms, in which 1, 2 or 3 -CH ₂ groups through

0 S O O

II H I! II -O-, -S-, -N-, -C-, -C-, -S-, -S- can be replaced, with the proviso that -O- not

I II R O is next to -S- or -N- and -S- is not next to -N-,

R R

proteinogenic amino acids bound via the C-terminal end or the N-terminal end, or their N-protected or carbonyl-protected derivatives or a terpene with 5 to 20 C atoms,

- 2 R ¹ and / or 2 R ² of two preferably non-adjacent chain links

R ^{3 is} the group [- (CH ₂ ) _m -Z- (CH ₂ ) _n -] _p

R ⁴ in which Z has the meaning given above, and R ³ and R ⁴ H or a straight-chain or branched chiral or achiral alkylene chain having 1 to 20 C atoms, in which one or more CH ₂ groups can be replaced by

F Br Cl CN O R

I l I I II l

-O-, -S-, -C-, -N-, -C, -C-, -C-, -C-, -C-, -N-, -N-S-, -Si,

II l II III II IORS S0 ₂ RO R '

IR -Cycloalkanediyl with 3 to 8 carbon atoms, in which 1, 2 or 3 -CH ₂ groups through

O S O O

II II II II -O-, -S-, -N-, -C-, -C-, -S-, -S- can be replaced, with the proviso that -0- not I II

R O is next to -S- or -N- and -S- is not next to -N-, I I

R R

If R ¹ and R ^{2 are} not an electron pair, X and Y are the same or different H or the reactive group

O p

II II

-OH, CR, -NHR, -CR, -SH, -C ≡ N, -N = C = 0, -N = C = S, -N = C, -CH = CH ₂ , -C≡CH,

R R R O ß N-R '

I I I II / //

-Si-Cl, -Si-H, -Si-R \ -N ₃ . Cl, J, Br, -SN _ -NC -N = C = NR

I I I | i \ I \

R ^" R 'R' EHR NR",

Alkoxy oderR "'where R, R', R" or R '"are C _r C ₅ alkyl or H, or

Alkoxy or

CC ₅ alkanoyl with bond to a carbon atom or to a

Si atom.

A and B are R ¹ -X and R ^z -Y or together represent a bond and

m, n, the number 0, 1 or 2, o the number 3 to 8, p the number 1 or 2 and q the number 0 or 1 with the proviso that the sum of the indices m, n, o is greater / equal 9 and less than / equal to 29 and the proviso that at least one Z radical carries four mutually different substituents, one of which can be an electron pair.

Compounds in which Z are identical or different are preferred oo ιι il ι ι means -O-, -S-, -N-, -CO, -CN-, -Si-, -C- or phenyl or pyridyl, these with the groups - (CH ₂ ) _q -0 -, - (CH ₂ ) _q -S-, (CH ₂ ) _q -N- may be substituted in the ortho, meta or para position.

R ¹ and R ² are the same or different

a pair of electrons, -H or a straight-chain or branched chiral or achiral alkylene chain with 1 to 10 C atoms, in which one or more CH ₂ groups can be replaced by

F Cl Br I I I -O-, -C-, -N-, -C-, -C-, -C- ιι I O R

-Cycloalkanediyl with 5 to 7 carbon atoms, in which 1 or 2 CH ₂ groups by

-O-, -S-, -N-, -C- can be replaced, with the proviso that only -0- I II R O next to -C- and -N- next to -C- is II I II

O R O

proteinogenic amino acids bound via the C-terminal end,

If R ¹ and R ^{2 are} not an electron pair, X and Y are identical or different H or the reactive group

O R

II ι

-OH, -C-R, -NHR, -N = C = 0, -Si-Cl, Cl, Br, J,

R 'where R, R' are C ^ C ^ alkyl or H, or C ^ C, alkoxy or

CC ₂ alkanoyl bonded to an Si atom,

A and B represent R ¹ -X and R ² -Y or together represent a bond and m, n is the number 1, o the number 5 or 6 and q the number 0 or 1, with the proviso that that at least one Z radical carries four different substituents, one of which can be an electron pair.

The cyclic compounds can be prepared by reacting bis-alcoholates or bisthiolates in an inert solvent with bis-halides or bistosylates with high dilution. For working up, the solvent is removed under reduced pressure, the residue is added to a water-immiscible solvent and the mixture obtained is washed with water to remove salts. The solution of the product is dried, the solvent is stripped off and the residue is purified by chromatography on silica gel or aluminum oxide.

The compounds of the formula (I) can also be prepared by the methods cited below:

1. Houben-Weyl, Methods of Organic Chemistry, 4th ed., Vol. VIII, Oxygen Compounds III, pp. 653 to 671.

2. Houben-Weyl, Methods of Organic Chemistry, 4th ed., Vol. E4, carbonic acid derivatives, pp. 484 to 505.

3. Houben-Weyl, Methods of Organic Chemistry, 4th ed., Vol. E1, Phosphorus Compounds I, pp. 271 to 313.

4. Houben-Weyl, Methods of Organic Chemistry, 4th ed., Vol. E1, Phosphorverbiπdungen I, pp. 313 to 488.

5. Houben-Weyl, Methods of Organic Chemistry, 4th ed., Vol. E2, Phosphorus Compounds I, pp. 394 to 398.

6. Houben-Weyl, Methods of Organic Chemistry, 4th ed., Vol. E2, Phosphorus Compounds II, pp. 487 to 831.

7. Houben-Weyl, Methods of Organic Chemistry, 4th ed., Vol. E11, Organic Sulfur Compounds I, pp. 655 to 662.

8. Houben-Weyl, Methods of Organic Chemistry, 4th ed., Vol. E11, Organic Sulfur Compounds II, pp. 1098 to 1103. 9. Vincent J. Gatto and George W. Gokel; J. Am. Chem. Soc, 106 (1984), pp. 8240-8244.

10. S. Kulstad and L Ä. Malmsten; Acta Chem. Scand., B 33 (1979) 469-474.

11. Ju. B. Zelenconok, V. V. Orlovskij, D. L Rachmankulov; Jour. f. Prakt. Chem. 332 (1990) pp. 719-722.

12. B. Czech, A. Czech and R. A. Bartsch; Tetr. Lett., 24 (1983) pp. 1327-1328.

13. N. Ando, Y. Yamamoto, J. Oda, Y. Inouye; Synthesis 1978, pp. 688-690.

14. T. Miyazaki, S. Yanagida, A. Itoh and M. Okahara; Bull. Chem. Soc. Jpn., 55 (1982) pp. 2005-2009.

15. K. Ping-ün, M. Miki and M. Okahara; J.C.S. Chem. Comm., 1978, pp. 504-505.

16. F. Montaπari and P. Tundo, J. Org. Chem., 47 (1982) pp. 1298-1302.

17. C. J. Pedersen, J. Am. Chem. Soc, 89 (1967) pp. 7017-7036.

18. W. Raßhofer and F. Vögtle, Liebigs Ann. Chem., 1977, pp. 1340-1343.

19. B. Castro et J.R. Dormoy, Tetr. Lett. 32 (1991) pp. 1967-1970.

The compound of the formula (I) can be added to ferroelectric liquid-crystal mixtures and brought into or on orientation layers. The bond to the orientation layer can be via chemical coupling, i.e. Covalent bond, or by physisorption, i.e. by means of intermolecular forces of attraction. During physisorption, the strength of the coupling to the orientation layer molecules can be increased by incorporating polar or polarizable groups. The compound of general formula (I) is applied in concentrations of 0.01% to 25%, preferably 0.1% to 10%, in the liquid crystal mixture or in or on the orientation layer.

Such liquid crystal mixtures and / or orientation layers can be used in electro-optical or completely optical components.

The following examples serve to further explain the invention. Examples:

1. Synthesis of tert-butoxymethyl-18-crown-6

100 mmol 3,6-dioxa-4- (tert-butoxymethyl) -1,8-octanediol (in enantiomerically pure or in racemic form) are dissolved in 100 ml tetrahydrofuran, first mixed with 10 ml water and then with 14 g potassium hydroxide. The mixture is heated under reflux and 45.8 g (100 mmol) of triethylene glycol bistosylate are added. The mixture is refluxed for a further 3 hours. The solvent is removed in vacuo and the residue is mixed with 100 ml of water. It is extracted continuously with diethyl ether for 10 days. The diethyl ether is drawn off, the water still present is removed azeotropically with benzene and the residue is stirred with an excess of potassium tetrafluoroborate in CH ₂ Cl ₂ . After filtration, the solution is concentrated. After adding diethyl ether, 2- (tert-butoxymethyl) -18-crown-6 is obtained as a potassium tetrafluoroborate complex (mp. 125-126 ° C.). In order to release the ligand, 5 g of the complex are dissolved in 25 ml of water and extracted continuously with diethyl ether for 15 hours. The diethyl ether is drawn off and the residue is dried azeotropically with benzene. To remove the entrained complex, diethyl ether is added and the mixture is filtered off. The residue is distilled (bp. 166-167 ° C / 0.3 Torr).

2. Synthesis of tert-butoxymethyl-15-crown-5

Analogously to Example 1, but instead of triethylene glycol bistosylate, diethylene glycol bistosylate is used and the corresponding sodium salts are used instead of the potassium salts.

3. Synthesis of tert-butoxymethyl-12-crown-4

Analogously to Example 1, but instead of triethylene glycol bistosylate, ethylene glycol bistosylate is used and the corresponding lithium salts are used instead of the potassium salts. 4. Synthesis of tert-butoxymethyl-21-crown-7

Analogously to Example 1, but instead of triethylene glycol bistosylate, tetraethylene glycol bistosylate is used and the corresponding rubidium salts are used instead of the potassium salts.

5. Synthesis of hydroxymethyl-18-crown-6

4 ml of 54% tetrafluoroboric acid diethyl ether complex are added to 10 g of potassium tetrafluoroborate complex of tert-butoxymethyl-18-crown-6 in 30 ml of CH ₂ Cl ₂ and the mixture is stirred at room temperature for 20 minutes. It is neutralized with potassium carbonate, filtered off, the solvent is stripped off and the product is precipitated as potassium tetrafluoroborate complex by adding diethyl ether (mp. 144-145 ° C.).

6th - 8th synthesis of hydroxymethyl-12-crown-4, hydroxymethyl-15-crown-5,

Hydroxymethyl-21-crown-7

Synthesis analogous to example 5.

9. separation of hydroxymethyl crown ethers (hydroxymethyl-18-crown-6, hydroxymethyl-15-crown-5, hydroxymethyl-12-crown-4, hydroxymethyl-21-crown-7)

10 mmol of racemic hydroxymethyl crown ether is dissolved in 50 ml of CH ₂ Cl ₂ and 10 mmol of diacetyltartaric anhydride and 0.1 mmol of 4-dimethylaminopyridine are added at 0 ° C. After stirring for 1 hour, the solvent is stripped off and the diastereomeric hydrogen tartrate esters are separated by recrystallization.

10. Enantiomer separation of hydroxymethyl-15-crown-5

10 mmol racemic hydroxymethyl-15-crown-5 is dissolved in 50 ml CH ₂ CI ₂ and at 0 ° C with 10 mmol 3-nitrophthalic anhydride and 0.1 mmol 4- Dimethylaminopyridine added. After stirring for 1 hour, 10 mmol of brucine are added. After a further hour, the solvent is stripped off and the diastereomeric 3-nitrophthalic esters are separated by recrystallization.

11. Saponification of hydroxymethyl-18-crown-6-diacetyltartaric acid monoester

5 mmol of hydroxymethyl-18-crown-6-diacetyltartaric acid monoester are dissolved in the required amount of tetrahydrofuran and 5 equivalent 4 normal lithium hydroxide solutions are added dropwise at 10 ° C. It is mixed with 100 ml of saturated sodium chloride solution, the product extracted with CH ₂ Cl ₂ off, dried and purified by chromatography on Si0 ₂ with CH ₂ Cl ₂ / methanol 20/1.

12. Synthesis of chiral 8- (1, 4,7,10,13-pentaoxa-cyclopentadecan-2-yl) -6-oxa-octanoic acid

2 mmol (+) -hydroxymethyl-15-crown-5 are dissolved in 10 ml of dimethylformamide and 4 mmol of sodium hydride are added. After the evolution of hydrogen has ended, the mixture is stirred at 50 ° C. for 45 minutes and then 2 mmol of 6-bromohexanoic acid are added. The mixture is stirred at 50 ° C for 2 hours. Then 20 ml of water are added and the mixture is shaken out several times with CH ₂ CI ₂ . The CH ₂ CI ₂ phase is removed on a rotary evaporator and the residue is chromatographed on Si0 ₂ . Analogous reactions can be carried out with (-) - hydroxymethyl-15-crown-5 and with (+) - or (-) - hydroxymethyl-18-crown-6, (+) - or (-) - hydroxymethyl-21- crown-7, or with (+) - or (-) - hydroxymethyl-l 2-crown-4 as alcohol component and with 8-bromooctanoic acid, 9-bromononanoic acid, 10-bromodecanoic acid, 11-bromundecanoic acid, 12-bromododecanoic acid, 5- Perform bromovaleric acid and 4-bromobutyric acid as the acid component.

13. Synthesis of (+) - 8- (1, 4,7,10,13-pentaoxa-cyclopentadecan-2-yl) -6-oxa-octanoic acid ethyl ester

1 mmol (+) -8- (1, 4,7,10,13-pentaoxa-cyclopentadecan-2-yl) -6-oxa-octanoic acid is in CH ₂ CI ₂ dissolved, mixed with 2.2 mmol of N-methylmorpholine and, under the rejection of light, with 1.1 mmol of benzotriazolyloxy-tris [pyrrolidino] phosphonium hexafluorophosphate (PyBOP ^® ). After 18 hours, the mixture is washed with 1 normal hydrochloric acid and with saturated sodium bicarbonate solution, concentrated on a rotary evaporator and the residue is chromatographed on SiO ₂ with CH ₂ Cl ₂ / MeOH (20/1).

The substances mentioned under Example 12 and their enantiomers can be reacted analogously.

14. Synthesis of aza-coronandamideπ

1 g Kryptofix ^® 22 is dissolved in 50 ml CH ₂ CI ₂ . 1.2 ml (3.81 mmol) of triethylamine are added and 0.1 g of 4-dimethylaminopyridine is added as a catalyst. 1.73 g (8 mmol) of (1S) - (-) - camphanoyl chloride are then added. The mixture is stirred at room temperature for 18 hours. The reaction solution is washed 2 times with 1N HCl, then 2 times with saturated NaHC0 ₃ solution. It is dried over MgSO ₄ and the solvent is stripped off. It is chromatographed on Si0 ₂ with CH ₂ CI ₂ / MeOH (20/1).

NMR (CDCI ₃ ): 3.4-3.8 ppm (m, 24H, -CH ₂ -CH ₂ -0), 2.75-1, 50 ppm (m, 8H, C-CH ₂ - CH ₂ - C), 1, 2 ppm (s, 6H, -CH ₃ ), 1, 1 ppm (s, 6H, -CH ₃ ), 0.95 ppm (s, 6H, -CH ₃ ).

Analogously, for example, Kryptofix ^® 21, 23, 1-Aza-12-krone-4, 1-Aza-15-krone-5, 1-Aza-18-krone-6 and 1-Aza-21-krone-7 can be implemented , other carbon or sulfonic acid chlorides can also be used.

Claims

iPatent claims: 1. Compound of the general formula X A [- (CH ₂ ) _m - Z - (CH ₂ ) _n -] B I. R ² in the Z the same or different the group 0 0 0 0 o II II II II II -O-, -S-, -S-, -S-0-, -S-N-, -S- -S-N- -N- -N- I II i i o -N-0-, O-N-O-, -Si-, -C-, -P-, -P-O-, -P-N-, I I I I | I | ι 0 O 1 ι O O O O O II II II II II -Si-O-, -O-Si-0-, -P-, -PO-, -PN-, -CN-, -C-0-, or phenyl or pyridyl, these with the groups - (CH ₂ ) _q -0-, - (CH ₂ ) _q -S-, - (CH ₂ ) _q -N-, O 0 0 0 0 • (CH ₂ ) _q -Si-, - (CH ₂ ) _q ) -CN-, - (CH ^ -NC-, - (CH ₂ ) _q -C-0-, - (CH ₂ ) _q -0- C-, - (CH ^ -C- may be substituted in the ortho, meta or para position, R ¹ and R ² are the same or different a pair of electrons, - H or a straight-chain or branched chiral or achiral Alkylene chain with 1 to 20 carbon atoms, in which one or more CH ₂ groups can be replaced by -O-, -S-, -,

-Cycloalkanediyl with 3 to 8 carbon atoms, in which 1, 2 or 3 -CH ₂ groups through -O-, -S-, - can be replaced, with the proviso that -0- not

next to -S- or -N- and -S- not next to -N-, II ^a R R proteinogenic amino acids bound via the C-terminal end or the N-terminal end, or their N-protected or carbonyl-protected derivatives or a terpene with 5 to 20 C atoms, - 2 R ¹ and / or 2 R ² of two preferably non-adjacent chain links R ^{3 is} the group [- (CH ₂ ) _m -Z- (CH ₂ ) _n -] _p R ⁴ in which Z has the meaning given above, and R ³ and R ⁴ H or a straight-chain or branched chiral or achiral alkylene chain having 1 to 20 C atoms, in which one or more CH ₂ groups can be replaced by -O-, -S-, - ir or '

-Cycloalkanediyl with 3 to 8 C atoms, in which 1, 2 or 3 -CH ₂ groups by OSO 0 -O-, -S-, -N-, -C "-, -C ll-, -S II-, -S ü- can be replaced, with the proviso that -O- not R 0 in addition to -S- or -N- and -S- are not next to -N-, II ^a R R If R ¹ and R ^{2 are} not an electron pair, X and Y are the same or different H or the reactive group O p II ll -OH, CR, -NHR, -CR, -SH, -C ≡ N, -N = C = 0, -N = C = S, -N = C, -CH = CH ₂ , -C≡CH, R R R O R N-R ' I I I | i / // -Si-Cl, -Si-H, -Si-R ', -N ₃ , Cl, J, Br, -SN -NC -N = C = NR I I I II \ I \ R 'R' R 'O H R N ^ R ", R "'where R, R', R" or R '"mean CC ₅ alkyl or H, or CC ₅ alkoxy or C.-C ₅ alkanoyl with a bond to a carbon atom or to a Si atom. A and B represent R -X and R ² -Y or together represent a bond and m, n, the number 0, 1 or 2, o the number 3 to 8, p the number 1 or 2 and q the number 0 or 1 with the proviso that the sum of the indices m, n, o is greater / equal 9 and less than / equal to 29 and the proviso that at least one radical Z carries four mutually different substituents, one of which can be an electron pair. 2. Connection according to claim 1, characterized in that the symbols have the following meaning. Z the same or different oo II ll ι ι -O-, -S-, -N-, -C-O, -C-N-, -SI-, -C- or phenyl or pyridyl, where these I l can be substituted with the groups - (CH ₂ ) _q -0-, - (CH ₂ ) _q -S-, (CH ₂ ) _q -N- in the ortho, meta or para position. R ¹ and R ² are the same or different a pair of electrons, -H or a straight-chain or branched chiral or achiral alkylene chain with 1 to 10 C atoms, in which one or more CH ₂ groups can be replaced by F Cl Br I i I -O-, -C-, -N-, -C-, -C-, -C- II l O R -Cycloalkanediyl with 5 to 7 carbon atoms, in which 1 or 2 CH ₂ groups by -0-. -S-, -N-, -C- can be replaced, with the proviso that only -O- I II R O next to -C- and -N- next to -C- lies li I II O R O proteinogenic amino acids bound via the C-terminal end, X and Y are the same or different, if R ¹ and R ^{2 are} not an electron pair, H or the reactive group 0 R II ι -OH, -CR, -NHR, -N = C = 0, -Si-Cl, Cl, Br, J, i R 'where R, R' C ^ -Alky! or H, or dC ₂ alkoxy or CC ₂ alkanoyl bonded to an Si atom, A and B represent R ^ X and R ² -Y or together represent a bond and m, n is the number 1, o the number 5 or 6 and q the number 0 or 1, with the proviso that that at least one Z radical carries four different substituents, one of which can be an electron pair. 3. Ferroelectric liquid crystal mixture, characterized by a content of 0.01 to 25 wt .-% of the compound according to claim 1. 4. Ferroelectric liquid crystal mixture, characterized by a content of 0.01 to 25 wt .-% of the compound according to claim 2. 5. orientation layer characterized by a content of 0.01 to 25 wt .-% of the compound of claim 1. 6. Orientation layer characterized by a content of 0.01 to 25 wt .-% of the compound according to claim 2. 7. Electro-optical or completely optical components which contain a liquid crystal mixture according to claim 3 or 4. 8. Electro-optical or completely optical components which contain an orientation layer according to claim 5 or 6.