DE19748818A1 - Optically active, smectic liquid crystal mixture, containing a temperature stable polyfluorinated cyclohexane derivative useful of the fabrication of switching and display devices - Google Patents

Abstract

A polyfluorinated cyclohexane derivative contains 2-4 ring systems of at least 5 members, and exhibits a stable smectic liquid crystalline phase, and is optically active. A polyfluorinated cyclohexne derivative (I) is of formula (1) and contains 2-4 ring systems of at least 5 members: R<1>(-A<1>-M<1>)a(-A<2>-M<2>)b(-A<3>)c-M<3>-B(1) where: B = perfluorocyclohexyl (C6F11); R<1> = a) H, -OCF3, -CF3, -CN, -F, -Cl, -OCH2F, -OCHF2, -CHF2 or -CH2F; b) 1-20C alkyl whereby one or more non-neighbouring and non-terminal CH2 groups are optionally replaced by -O-, -S-, -CO-O-, -O-CO-, -O-CO-O- or -Si(CH3)2- and/or one or more CH2 groups are optionally replaced by -CH=CH-, -C equivalent to C-, cyclopropane-1,2-dinyl; 1,4-phenylene; 1,4-cyclohexylene or 1,3-cyclopentylene and/or one or more H atoms are optionally replaced by F and/or Cl and/or the terminal CH3 groups are optionally replaced by the following chiral groups (optically active or racemic): R<3> - R<7> = H, 1-16C alkyl whereby one or more non-neighboring and non-terminal CH2 groups are optionally replaced by -O- and/or one or two CH2 groups are replaced by -CH=CH-. R<4> and R<5> together may be -(CH2)4- or -(CH2)5- if bonded to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system; M<1>, M<2> = -CO-O-, -O-CO-, -CO-S-, -S-CO-, -CS-O-, -CS-S-, -O-CS-, -S-CS-, -CH2-O- M<3> = -O-CO-, -O-CH2-, -CH=CH-, -CH2-CH2-, -CH2CH2-O-CH2-, -CH2-CH2-O-C(=O)-, -CH2-CH2-CH=CH-, -(CH2)4- or a single bond; A<1>, A<2>, A<3> = 1,4-phenylene or pyridine-2,5-diyl, optionally having one or more H atoms substituted by F, Cl and/or CN; pyrazine-2,5-diyl, pyridazine-3,6-diyl, pyrimidine-2,5-diyl, or thiophene-2,5-diyl, optionally having one or two H atoms substituted by F, Cl and/or CN; 1,4-cyclohexylene optionally having one or two H atoms replaced by CN, CH3 and/or F; napthalene-2,6-diyl, napthalene-1,4-diyl or napthalene-1,5-diyl optionally having one or more H atoms replaced by F, Cl and/or CN and/or one or two CH groups replaced by N; 1,3,4-thiadiazol-2,5-diyl, 1,3-dioxane-2,5-diyl, 1,3-dithian-2,5-diyl , 1,3-thiazol-2,4-diyl, thiophene-2,4-diyl or 1,3-thiazol-2,5-diyl, optionally having one H atom replaced by F, Cl and/or CN; napthalene-2,6-diyl, napthalene-1,4-diyl or napthalene-1,5-diyl whereby one or more H atoms are replaced by F, Cl and/or CN and/or one or two CH groups are replaced by N; phenanthrene-2,7-diyl or 9,10-dihydrophenanthrene-2,7-diyl having one or more H atoms replaced by F and/or one or two CH groups replaced by N; indan-2,5-diyl, indan-1-one-2,5-diyl, benzothiazol-2,6-diyl, benzothiazol-2,5-diyl, benzoxazol-2,6-diyl, benzoxazol-2,5-diyl, benzofuran-2,5-diyl, benzofuran-2,6-diyl, 2,3-dihydrobenzofuran-2,5-diyl, piperazine-1,4-diyl, piperazine-2,5-diyl or 1,3-dioxaborinane-2,5-diyl; a, b, c = 0 or 1. Independent claims are included for (i) a liquid crystal mixture (II) containing one or more polyfluorinated cyclohexane derivatives (I) and (ii) a switch and/or display device containing an optically active, smectic liquid crystal mixture (II).

Description

In addition to nematic and cholesteric liquid crystals, more recently also optically active inclined smectic (ferroelectric) liquid crystals in commercial display devices used.

Clark and Lagerwall were able to show that the use of ferroelectric liquid crystals (FLC) in very thin cells leads to optoelectric switching or Display elements leads, which compared to the conventional TN ("twisted nematic ") cells have up to a factor 1000 faster switching times (see e.g. B. EP-A 0 032 362). Because of these and other beneficial properties, e.g. B. the bistable switching option and the almost independent viewing angle Contrasts, FLCs are basically for application areas like computer displays well suited.

For the use of FLCs in electro-optical or completely optical Components require either connections, the inclined or orthogonal Form smectic phases and are optically active themselves, or you can by Doping of compounds that form such smectic phases themselves but are not optically active, with optically active ferroelectric connections induce smectic phases. The desired phase should be over a the largest possible temperature range to be stable.

A uniform planar orientation of the liquid crystals is necessary to achieve a good contrast ratio in electro-optical components. A good orientation in the S _A and S * _C phase can e.g. B. achieve if the phase sequence of the liquid crystal mixture with decreasing temperature is:

Isotropic → N * → S _A → S * _C

The prerequisite is that the pitch (pitch of the helix) is very large in the N * phase (larger than 10 µm) or, even better, completely compensated (see e.g. T. Matsumoto et al., Proc. of the 6th Int. Display Research Conf., Japan Display, Sept. 30-Oct. 2, 1986, Tokyo, Japan, pp. 468-470; M. Murakami et al., Ibid. P. 344-p. 347). This one reaches z. B. by adding to the chiral liquid crystal mixture in the N * phase e.g. B. has a left-turning helix, one or more optically active Adding dopants that induce a right-handed helix in such amounts that the helix is compensated.

For the use of the SSFLCD effect (Surface Stabilized Ferroelectric Liquid Crystal Display) by Clark and Lagerwall for uniform, planar orientation further prerequisite that the pitch in the smectic C * phase is much larger is as the thickness of the display element (Mol. Cryst. Liq. Cryst. 1983, 94, 213 and 1984, 114, 151.

The optical switching time τ [µs] of ferroelectric liquid crystal systems, which should be as short as possible, depends on the rotational viscosity of the system γ [mPa.s], the spontaneous polarization P _s [nC / cm ² ] and the electric field strength E [V / m] depending on the relationship

Since the field strength E by the electrode spacing in the electro-optical component and is determined by the applied voltage, the ferroelectric Display medium has low viscosity and a high spontaneous polarization, so that a short switching time is achieved.

Finally, in addition to thermal, chemical and photochemical stability for the optical anisotropy Δn and the dielectric anisotropy Δε values within certain, through the display geometry (layer thickness) or control method conditional limits (see, e.g., S.T. Lagerwall et al., "Ferroelectric Liquid Crystals for Displays "SID Symposium, Oct. Meeting 1985, San Diego, Ca, USA).  

All of these requirements can only be met with mixtures of several components. The basis (or matrix) used is preferably compounds which, if possible, already have the desired phase sequence I → N → S _A → S _C. Other components of the mixture are often added to lower the melting point and broaden the S _C - and usually also the N phase, to induce optical activity, to compensate for pitch and to adjust the optical and dielectric anisotropy, but, for example, do not increase the rotational viscosity if possible shall be.

Ferroelectric liquid crystal displays can also be operated by using the DHF (Distorted Helix Formation) effect or the PSFLCD effect (Pitch Stabilized Ferroelectric Liquid Crystal Display, also called SBF = Short Pitch Bistable Ferroelectric Effect). The DHF effect was described by BI Ostrovski in Advances in Liquid Crystal Research and Applications, Oxford / Budapest 1980, 469 ff., The PSFLCD effect is described in DE-A 39 20 625 and EP-A 0 405 346. In contrast to the SSFLCD effect, a liquid crystal material with a short S _C pitch is required to use these effects.

Cyclohex-3-en-1-yl derivatives which are substituted by a maximum of 2 F atoms e.g. B. from DE-A 1 96 07 996 known. Cyclohexane derivatives with 4,4-difluoro substitution are z. B. from JP-A 06/239 775 known. Cyclohexane derivatives by a Perfluoroalkyl chain are substituted, for. B. from JP-A 01/501 945, others mesogenic cores with perfluoroalkyl side chain z. B. from Ferroelectrics 1988, 85, 375-384 or US 4,886,619; 5,082,587; 5,254,747; 5,262,082; 5,437,812 or 5,482,650.

But since the development, especially of ferroelectric Liquid crystal mixtures, in no way considered complete the manufacturers of displays are on the most varied Components for mixtures interested. This u. a. also because only that  Interaction of the liquid crystalline mixtures with the individual components of the Display device or the cells (z. B. the orientation layer) conclusions on the quality of the liquid crystalline mixtures.

The object of the present invention was therefore to create new compounds To provide, which are suitable in liquid crystalline mixtures, the To improve the property profile of these mixtures.

It has now surprisingly been found that the polyfluorinated compounds of the formula (I) are particularly suitable for use in liquid crystal mixtures.

The invention therefore relates to polyfluorinated cyclohexane derivatives of the formula (I),

R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b (-A ³ ) _c -M ³ -B (I)

where the symbols and indices have the following meanings:
B is perfluorocyclohexyl (C ₆ F ₁₁ ), hereinafter with the formula:

designated
R ¹ is

• a) Hydrogen, -OCF ₃ , -CF ₃ , -CN, -F, -Cl, -OCHF ₂ , -OCH ₂ F, -CHF ₂ or -CH ₂ F
• b) a straight-chain or branched alkyl radical (with or without asymmetrical carbon atom) with 1 to 20 carbon atoms, where
  • b1) one or more non-adjacent and non-terminal CH ₂ groups by -O-, -S-, -CO-O-, -O-CO-, -O-CO-O- or -Si (CH ₃ ) ₂ - can be replaced and / or
  • b2) one or more CH ₂ groups can be replaced by -CH = CH-, -C∼C-, cyclopropane-1,2-diyl, 1,4-phenylene, 1,4-cyclohexylene or 1,3-cyclopentylene and or
  • b3) one or more H atoms can be replaced by F and / or Cl and / or
  • b4) the terminal CH ₃ group can be replaced by one of the following chiral groups (optically active or racemic):
    

R ³

, R ⁴

, R ⁵

, R ⁶

, R ⁷

are the same or different

• a) hydrogen
• b) a straight-chain or branched alkyl radical (with or without asymmetric carbon atom) with 1 to 16 carbon atoms, where
  • b1) one or more non-adjacent and non-terminal CH ₂ groups can be replaced by -O- and / or
  • b2) one or two CH ₂ groups can be replaced by -CH = CH-,
• c) R ⁴ and R ⁵ together also - (CH ₂ ) ₄ - or - (CH ₂ ) ₅ - if they are bonded to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system;

M ¹

, M ²

, are the same or different -CO-O-, -O-CO-, -CO-S-, -S-CO-, -CS-O-, -CS-S-, -O-CS-, -S- CS-, -CH ₂

-O-, -O-CH ₂

-, -CH ₂

-S-, -S-CH ₂

-, -CH = CH-, -C∼C-, -CH ₂

-CH ₂

-CO-O-, -O-CO-CH ₂

-CH ₂

- or a single bond;
M ³

is -O-CO-, -O-CH ₂

-, -CH = CH-, - CH ₂

-CH ₂

-, -CH ₂

-CH ₂

-OCH ₂

-, -CH ₂

- CH ₂

-OC (= O) -, -CH ₂

-CH ₂

-CH = CH-, -CH ₂

-CH ₂

-CH ₂

-CH ₂

- or, if the index c is 1, a single bond
A ¹

, A ²

, A ³

are identical or different 1,4-phenylene, where one or more H atoms can be replaced by F, Cl and / or CN, pyrazine-2,5-diyl, one or two H atoms being replaced by F, Cl and / or CN can be replaced, pyridazine-3,6-diyl, where one or two H atoms can be replaced by F, Cl and / or CN, pyridine-2,5-diyl, where one or more H atoms can be replaced by F , Cl and / or CN can be replaced, pyrimidine-2,5-diyl, where one or two H atoms can be replaced by F, Cl and / or CN, 1,4-cyclohexylene, where one or two H atoms by CN and / or CH ₃

and / or F can be replaced, (1,3,4) -thiadiazole-2,5-diyl, 1,3-dioxane-2,5-diyl, 1,3-dithiane-2,5-diyl, 1, 3-thiazole-2,4-diyl, where one H atom can be replaced by F, Cl and / or CN, 1,3-thiazole-2,5-diyl, one H atom by F, Cl and / or CN can be replaced, thiophene-2,4-diyl, where an H atom can be replaced by F, Cl and / or CN, thiophene-2,5-diyl, where one or two H atoms can be replaced by F, Cl and / or CN can be replaced, naphthalene-2,6-diyl, naphthalene-1,4-diyl or naphthalene-1,5-diyl, one or more H atoms being replaced by F, Cl and / or CN can and / or one or two CH groups can be replaced by N, phenanthrene-2,7-diyl or 9,10-dihydrophenanthrene-2,7-diyl, one, two or more H atoms being replaced by F. and / or one or two CH groups can be replaced by N, indan-2,5-diyl, indan-1-one-2,5-diyl, benzothiazole-2,6-diyl, benzothiazole-2,5- diyl, benzoxazole-2,6-diyl, benzoxazole-2,5-diyl, benzofuran-2,5-d iyl, benzofuran-2,6-diyl, 2,3-dihydrobenzofuran-2,5-diyl, piperazine-1,4-diyl, piperazine-2,5-diyl or 1,3-dioxaborinane-2,5-diyl;
a, b, c are 0 or 1, with the proviso that the compound of formula (I) contains at least two and not more than four five- or more-membered ring systems.

With the provision of compounds of formula (I), the Range of liquid crystalline substances, which are among different technical aspects for the production of liquid crystalline Mixtures are suitable, considerably widened.

In this connection, the compounds of formula (I) have a wide range Scope of application. Depending on the choice of substituents, they can serve as base materials from which liquid crystalline phases for the majority are composed; but connections of the Formula (I) liquid-crystalline base materials from other classes of compounds can be added, for example, the dielectric and / or optical anisotropy to influence such a dielectric and / or in order to To optimize threshold voltage and / or its viscosity.

The compounds of the formula (I) according to the invention are particularly suitable for use in nematic and smectic liquid-crystal mixtures, and in the case of nematic mixtures particularly for "active matrix displays" (AM-LCD) (see, for example, BC Prince, Seminar Lecture Notes, Volume I) , p. M-3/3-M-22, SID International Symposium 1997, BB Bahadur, Liquid Crystal Applications and Uses, Vol 1, p. 410, World Scientific Publishing, 1990, E. Lüder, Recent Progress of AM LCD's, Proceedings of the 15 ^th International display Research Conference, 1995, p. 9-12) and "in-plane switching displays" (IPS-LCD), in the case of smectic liquid crystal mixtures for ECB displays (Electric controlled birefringence), for electroclinic Displays and optically active inclined smectic (ferroelectric) displays. The compounds of the formula (I) according to the invention are particularly suitable for use in FLC mixtures which form a so-called "spontaneous bookshelf geometry".

The symbols and indices in the formula (I) preferably have the following meanings:
R ¹ is

• a) hydrogen,
• b) a straight-chain or branched alkyl radical (with or without asymmetrical carbon atom) with 1 to 18 carbon atoms, where
  • b1) one or more non-adjacent and non-terminal CH ₂ groups can be replaced by -O-, -CO-O-, -O-CO-, -O-CO-O or -Si (CH ₃ ) ₂ and / or
  • b2) a CH ₂ group can be replaced by cyclopropane-1,2-diyl, 1,4-phenylene or trans-1,4-cyclohexylene and / or
  • b3) one or more H atoms can be replaced by F and / or
  • b4) the terminal CH ₃ group can be replaced by one of the following chiral groups (optically active or racemic):

R ¹

is particularly preferred

• b) a straight-chain or branched alkyl radical (with or without asymmetrical carbon atom) with 1 to 16 carbon atoms, where
  • b1) one or two non-adjacent and non-terminal CH ₂ groups can be replaced by -O-, -CO-O-, -O-CO-, -O-CO-O- or -Si (CH ₃ ) ₂ - and or
  • b2) a CH ₂ group can be replaced by 1,4-phenylene or trans-1,4-cyclohexylene and / or
  • b3) one or more H atoms can be replaced by F and / or
  • b4) the terminal CH ₃ group can be replaced by one of the following chiral groups (optically active or racemic):

R ³

, R ⁴

, R ⁵

, R ⁶

, R ⁷

are preferably the same or different

• a) hydrogen
• b) a straight-chain or branched alkyl radical (with or without an asymmetric carbon atom) with 1 to 14 carbon atoms, where
  • b1) one or two non-adjacent and non-terminal CH ₂ groups can be replaced by -O- and / or
  • b2) a CH ₂ group can be replaced by -CH = CH-,
• c) R ⁴ and R ⁵ together also - (CH ₂ ) ₄ - or - (CH ₂ ) ₅ - if they are bound to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system.

R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ are particularly preferably the same or different

• a) hydrogen
• b) a straight-chain or branched alkyl radical (with or without an asymmetric carbon atom) with 1 to 14 carbon atoms, where
  • b1) a non-terminal CH ₂ group can be replaced by -O- and / or
• c) R ⁴ and R ⁵ together also - (CH ₂ ) ₄ - or - (CH ₂ ) ₅ - if they are bound to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system.

M ¹ , M ² are preferably identical or different -CO-O-, -O-CO-, -CH ₂ -O-, -O-CH ₂ -, -CH = CH-, -C∼C-, -CH ₂ -CH ₂ -CO-O-, -O-CO-CH ₂ -CH ₂ - or a single bond.
M ¹ , M ² are particularly preferably identical or different -CO-O-, -O-CO-, -CH ₂ -O-, -O-CH ₂ - or a single bond.
M ³ is preferably -O-CO-, -O-CH ₂ -, - CH ₂ -CH ₂ -, -CH ₂ -CH ₂ -CH ₂ -CH ₂ - or a single bond.
M ³ is particularly preferably -O-CO-, -OCH ₂ -, or a single bond.
A ¹ , A ² , A ³ are preferably identical or different 1,4-phenylene, it being possible for one or two H atoms to be replaced by F and / or CN, pyridine-2,5-diyl, one or two H- Atoms can be replaced by F and / or CN, pyrimidine-2,5-diyl, where one or two H atoms can be replaced by F, trans-1,4-cyclohexylene, where one or two H atoms can be replaced by CN and / or CH ₃ and / or F can be replaced, (1,3,4) thiadiazole-2,5-diyl, 1,3-dioxane-2,5-diyl, 1,3-thiazole-2,5- diyl, where an H atom can be replaced by F and / or CN, or naphthalene-2,6-diyl.
A ¹ , A ² , A ³ are particularly preferably identical or different 1,4-phenylene, it being possible for one or two H atoms to be replaced by F, pyridine-2,5-diyl, one H atom being replaced by F. may, pyrimidine-2,5-diyl, trans-1,4-cyclohexylene, where one or two H atoms can be replaced by CN and / or CH ₃ and / or F, (1,3,4) -Thiadiazol- 2,5-diyl or 1,3-thiazole-2,5-diyl.
A ³ is very particularly preferably 1,4-phenylene, it being possible for one or 2 H atoms to be replaced by F, or (1,3,4) -Thiadiazol-2,5-diyl, 1,3-thiazol-2, 5-diyl or pyrimidine-2,5-diyl.

The following compounds of the formulas (Ia) to (It) are very particularly preferred:

in which mean:
R ^{8 is} a straight-chain or branched alkyl chain with 1 to 19 C atoms, it being possible for one or two H atoms on adjacent C atoms to be replaced by F and / or one or more —CH ₂ - groups by the —CF ₂ groups and one or two non-adjacent -CH ₂ groups can also be replaced by -O- and / or -OC (= O) -;
R ^{9 is} a straight-chain alkyl chain of 1 to 12 carbon atoms;
X, Y the same or different H or F.

The compounds according to the invention are prepared per se methods known from the literature, as used in standard works on organic synthesis, e.g. B. Houben-Weyl, Methods of Organic Chemistry, Georg-Thieme-Verlag, Stuttgart.

The production takes place under reaction conditions for the above Implementations are known and suitable. It can also be done by known, Make use of variants not mentioned here.

If desired, the starting materials can also be formed in situ, and in such a way that they are not isolated from the reaction mixture, but immediately further reacted to the compounds of formula (I).

Exemplary are in the following schemes synthetic routes for the synthesis of perfluorinated compounds of formula (I) specified, with others Procedures are conceivable and possible.  

Scheme 1

Compounds of the formula (IV) - corresponding to formula (I) with M ³ = -OCO- can be obtained, for example, by reacting mesogenic phenols of the formula II) - obtainable according to standard conditions or the specified literature references - with the commercially available perfluorocyclohexylcarboxylic acid fluoride (III; X = F) [CASNo. 6588-63-2], optionally in the presence of bases (inorganic, such as alkali or alkaline earth metal hydroxides, carbonates or bicarbonates, or organic such as pyridine, trialkylamine) or other acid scavengers.

In the case of X = OH, the reaction between (II) and (III) in the presence of Condensation reagents, e.g. B. dicyclohexylcarbodiimide.  

Scheme 2

Compounds of the formula (VI) - corresponding to formula (I) with M ³ = -OCH ₂ - - can be obtained, for example, by reacting mesogenic phenols of the formula (II) - obtainable according to standard conditions or the specified literature references - with the commercially available (perfluorocyclohexyl ) methanol (V) [CASNo. 28788-68-3]. For this purpose, (V) can be converted into the corresponding tosylate or triflate by reaction with toluenesulfonyl chloride or trifluoromethanesulfonic anhydride, which then in the presence of bases (preferably inorganic, such as hydroxides, carbonates or hydrogen carbonates of the alkali or alkaline earth metals) with the mesogenic phenols (II) to (VI) is implemented; it is also possible to convert the tosylate or triflate from (II) to (VI) using separately produced alkali metal or alkaline earth metal salts (phenolates) (Williamson ether synthesis).

It is also conceivable to implement (V) with (II) under the conditions of Mitsunobu reaction.  

Scheme 3

Compounds of the formula (X) - corresponding to formula (I) with M ³ = -CH = CH- - can be obtained, for example, by reacting mesogenic aldehydes of the formula (IX) - obtainable according to standard conditions or the specified literature references - with the triphenylphosphonium salt (VIII ) under the conditions of a Wittig reaction; (VIII) can be obtained from the commercially available (perfluorocyclohexyl) methanol (V) [CASNo. 28788-68-3] by implementation with e.g. B. phosphorus tribromide to (VII) and reaction of the latter with triphenylphosphine.

Compounds of formula (XI) - corresponding to formula (I) with M ³ = -CH ₂ CH ₂ - - can be obtained from (X) by hydrogenation in the presence of noble metal catalysts (e.g. palladium or platinum, optionally on a support material such as activated carbon, Calcium carbonate, but also as "Mohr") can be obtained.

Scheme 4

Compounds of the formula (XIV) - corresponding to formula (I) with M ³ = single bond and A ³ equal to (1,3,4) -thiadiazole-2,5-diyl - can be obtained, for example (analogously to EP-B 309 514) by Reaction of the hydrazides of mesogenic carboxylic acids of the formula (XII) - obtainable from the corresponding carboxylic acid esters or halides by reaction with hydrazine hydrate according to standard conditions or the literature references specified - with the commercially available perfluorocyclohexylcarboxylic acid fluoride (III; X = F) [CASNo. 6588-63-2] to the diacylhydrazines of the formula (XIII).

These can be dissolved using phosphorus pentasulfide or Lawesson's reagent Convert thiadiazoles of formula (XIV).

Scheme 5

Compounds of the formula (XVIII) - corresponding to formula (I) with M ³ = single bond and A ³ equal to 1,3-thiazole-2,5-diyl - can be obtained, for example (analogously to EP-B-0 439 170) by reacting mesogenic Compounds of the formula R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ -H with the oxazolidinone of the formula (XVI) under the conditions of a Friedel-Crafts acylation (e.g. Catalysis by aluminum trichloride) to compound (XVII); in this case M ¹ and M ^{2 are} particularly preferably single bonds.

XVI in turn becomes the commercially available perfluorocyclohexyl glycamide (XV) obtained by reaction with chloroformate.

The reaction step (XVII) to (XVIII) takes place under the influence of Phosphorus pentasulfide or Lawesson's reagent.

Scheme 6

Compounds of the formula (XX) - corresponding to formula (I) with M ³ = -CH ₂ CH ₂ OCO- can be obtained, for example, by reacting mesogenic alcohols of the formula (XIX) - obtainable according to standard conditions or the specified references - with the commercially available Perfluorocyclohexylcarboxylic acid fluoride (III; X = F) [CASNo. 6588-63-2], optionally in the presence of bases (inorganic, such as alkali or alkaline earth metal hydroxides, carbonates or bicarbonates, or organic such as pyridine, trialkylamine) or other acid scavengers.

In the case of X = OH, the reaction between (XIX) and (III) in the presence of Condensation reagents, e.g. B. dicyclohexylcarbodiimide.  

Scheme 7

Compounds of the formula (XXV) - corresponding to formula (I) with M ³ = single bond and A ³ equal to pyrimidine-2,5-diyl - can be obtained, for example, by reacting mesogenic compounds of the formula (XXIV) with the amidine (XXIII), the can in turn be produced from the nitrile (XXII) using ammonia in ethanol. (XXII) is obtainable from the commercially available (III) by reaction with aqueous ammonia to give the amide (XXI) and its dehydration using phosphorus pentoxide.

Scheme 8

Compounds of the formula (XXXIII) - corresponding to formula (I) with M ³ = single bond and A ³ equal to cyclohexane-1,4-diyl - can be obtained, for example, by reaction (Diels-Alder reaction) of substituted dienes of the formula (XXIX) with the ethene derivative (XXVII) to the cyclic olefin (XXXI), which can either be converted to (XXXIII) by hydrogenation (noble metal-catalyzed) or dehydrogenating (noble metals or dichlorodicyanobenzoquinone, DDQ) to (XXXIV). The ethene (XXVII) can in turn in a Wittig reaction, e.g. B. between methyltriphenylphosphonium bromide and the aldehyde (XXVI). (XXVI) is accessible from the commercially available acid fluoride (III) z. B. by a Rosenmund reduction.

For compounds of the formula (XXXII) - corresponding to formula (I) with M ³ = single bond and A ³ equal to 1,3-dioxane-2,5-diyl - the aldehyde (XXVI) is again a suitable starting material, since it can be, for . B. acid catalyzed in the presence of dehydrating agents or by azeotropic removal of the water of reaction with the 1,3-diols of the formula (XXX) to the dioxanes (XXXII).

The grouping R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ^3- -, a suitable, optionally protected precursor thereof, which in later steps according to methods known per se and familiar to the person skilled in the art this grouping can be transferred, or the functional derivatives mentioned in the diagrams with the grouping R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ^3- - can be prepared according to the person skilled in the art common methods.

The production takes place under reaction conditions for the above Implementations are known and suitable. It can also be done by known, Make use of variants not mentioned here.

For example, reference is made to DE-A 23 44 732, 24 50 088, 24 29 093, 2 50 294, 26 36 684, 27 01 591 and 27 52 975 for compounds with 1,4-cyclohexylene and 1,4-phenylene groups; DE-A 26 41 724 for compounds with pyrimidine-2,5-diyl Groups; DE-A 40 26 223 and EP-A 0 391 203 for compounds with pyridine-2,5-  diyl groups; DE-A 32 31 462 for compounds with pyridazine-3,6-diyl groups; EP-A 309 514 for compounds with (1,3,4) thiadiazole-2-5-diyl groups; WO-A 92/16500 for naphthalene-2,6-diyl groups; K. Seto et al, Journal of the Chemical Society, Chemical Communications 1988, 56 for dioxoborinan-2,5-diyl groups.

The production of disubstituted pyridines, disubstituted pyrazines, disubstituted Pyrimidines and disubstituted pyridazines can also be found, for example, in corresponding volumes of the series "The Chemistry of Heterocyclic Compounds" by A. Weissberger and E.C. Taylor (editor).

Dioxane derivatives are useful by reacting an appropriate one Aldehyde (or one of its reactive derivatives) with a corresponding one 1,3-diol (or one of its reactive derivatives), preferably in Presence of an inert solvent, such as benzene or toluene, and / or one Catalyst, e.g. B. a strong acid such as sulfuric acid, benzene or p-toluenesulfonic acid, at temperatures between about 20 ° C and about 150 ° C, preferably between 80 ° C and 120 ° C. As reactive derivatives of Starting materials are primarily suitable for acetals.

The aldehydes and 1,3-diols mentioned and their reactive derivatives are partly known, partly they can be followed without difficulty Standard methods of organic chemistry from compounds known from the literature getting produced. For example, the aldehydes are by oxidation corresponding alcohols or by reduction of nitriles or corresponding Carboxylic acids or their derivatives, the diols by reducing the corresponding Diester available.

Compounds in which an aromatic ring has at least one F atom is substituted, can also from the corresponding diazonium salts Exchange of the diazonium group for a fluorine atom, e.g. B. according to the methods of Balz and Schiemann.  

Regarding the connection of the ring systems with each other, reference is made to:
N. Miyaura, T. Yanagai and A. Suzuki in Synthetic Communications 11 (1981), 513-519, DE-C 39 30 663, MJ Sharp, W. Cheng, V. Snieckus in Tetrahedron Letters 28 (1987) 5093; GW Gray in J. Chem. Soc. Perkin Trans II 1989, 2041 and Mol. Cryst. Liq. Cryst. 172: 165, 204 (1991) 43 and 91; EP-A 0 449 015; WO-A 89/12039; WO-A 89/03821; EP-A 0 354 434 and EP-A 0 694 530 for the direct linking of aromatics and heteroaromatics; DE-A 32 01 721 for connections with -CH ₂ CH ₂ bridge members and Koji Seto et al. in Liquid Crystals 8 (1990) 861-870 for connections with -C∼C bridge members.

Esters of the formula (I) can also be esterified by appropriate carboxylic acids (or their reactive derivatives) with alcohols or phenols (or their reactive derivatives), according to the DCC method (DCC = dicyclohexylcarbodiimide) or analogous to DE-A 44 27 198. The corresponding carboxylic acids and alcohols or phenols are known or can be produced in analogy to known processes.

Suitable reactive derivatives of the carboxylic acids mentioned are particularly suitable the acid halides, especially the chlorides and bromides, furthermore the anhydrides, e.g. B. also mixed anhydrides, azides or esters, especially alkyl esters with 1-4 C atoms in the alkyl group.

Coming as reactive derivatives of the alcohols or phenols mentioned in particular the corresponding metal alcoholates or phenolates, preferably an alkali metal such as sodium or potassium.

The esterification is advantageous in the presence of an inert solvent carried out. Particularly suitable are ethers, such as diethyl ether, di-n- butyl ether, THF, dioxane or anisole, ketones such as acetone, butanone or  Cyclohexanone, amides, such as DMF or phosphoric acid hexamethyltriamide, Hydrocarbons, such as benzene, toluene or xylene, halogenated hydrocarbons, such as Carbon tetrachloride, dichloromethane or tetrachlorethylene and sulfoxides, such as Dimethyl sulfoxide or sulfolane.

Ethers of the formula (I) can be obtained by etherification of corresponding hydroxyl compounds, preferably corresponding phenols, the hydroxyl compound advantageously first being converted into a corresponding metal derivative, e.g. B. by treatment with NaH, NaNH ₂ , NaOH, KOH, Na ₂ CO ₃ or K ₂ CO _{3 is converted} into the corresponding alkali metal alcoholate or alkali metal phenolate. This can then be reacted with the corresponding alkyl halide, alkyl sulfonate or dialkyl sulfate, advantageously in an inert solvent such as acetone, 1,2-dimethoxyethane, DMF or dimethyl sulfoxide, or with an excess of aqueous or aqueous-alcoholic NaOH or KOH at temperatures between about 200 and 100 ° C.

With regard to the synthesis of special radicals R ¹ and R ² , reference is also made, for example, to
EP-A 0 355 008 for connections with silicon-containing side chains,
EP-A 0 292 954 for optically active compounds with an oxirane ester unit,
EP-A 0 263 437 for optically active compounds with an oxirane ether unit,
EP-A 0 361 272 for optically active compounds with a dioxolane ester unit,
EP-A 0 351 746 for optically active compounds with a dioxolane ether unit,
US 5,051,506 for optically active compounds with 2,3-difluoroalkyloxy unit,
US 4,798,680 for optically active compounds with 2-fluoroalkyloxy unit,
US 4,855,429 for optically active compounds with α-chloronarboxylic acid unit,
EP-A 0 552 658 for compounds with cyclohexylpropionic acid residues,
EP-A 0 318 423 for compounds with cyclopropyl groups in the side chain.

The invention also relates to the use of compounds of the formula (I) in liquid crystal mixtures, preferably smectic and nematic,  especially optically active inclined smectic (ferroelectric). The invention furthermore relates to liquid-crystal mixtures, preferably smectic and nematic, particularly preferably ferroelectric and antiferroelectric, very particularly preferably ferroelectric, containing one or more compounds of formula (I).

The liquid crystal mixtures according to the invention generally contain 2 to 35, preferably 2 to 25, particularly preferably 2 to 20 components.

They generally contain 0.01 to 80% by weight, preferably 0.1 to 60% by weight, particularly preferably 0.1 to 30% by weight, of one or more, preferably 1 to 10, particularly preferably 1 to 5, very particularly preferably 1 to 3, of Compounds of formula (I).

Further components of liquid crystal mixtures which contain compounds of the formula (I) according to the invention are preferably selected from the known compounds with smectic and / or nematic and / or cholesteric phases. These include e.g. B .:

• Derivatives of phenylpyrimidine, such as, for example, in WO-A-86/06401, U.S. 4,874,542,
• - Meta-substituted six-ring aromatics, such as, for example, in EP-A 0 578 054 described
• Silicon compounds, as described for example in EP-A 0 355 008,
• - Mesogenic compounds with only one side chain, such as in EP-A 0 541 081,
• Hydroquinone derivatives, as described for example in EP-A 0 603 786,
• - Phenylbenzoates, such as, for example, from P. Keller, Ferroelectrics 1984, 58, 3 and J. W. Goodby et al., Liquid Crystals and Ordered Fluids, Vol. 4, New York 1984 described and Thiadiazoles, as described for example in EP-A 0 309 514.

Examples of chiral, non-racemic dopants are:

• optically active phenylbenzoates, such as, for example, P. Keller, Ferroelectrics 1984, 58, 3 and J.W. Goodby et al., Liquid Crystals and Ordered Fluids, Vol. 4, New York 1984,
• - Optically active oxirane ethers, such as in EP-A 0 263 437 and WO-A-93/13093,
• - Optically active oxirane esters, as for example in EP-A 0 292 954 described
• optically active dioxolane ethers, such as, for example, in EP-A 0 351 746 described
• - Optically active dioxolane esters, such as, for example, in EP-A 0 361 272 described
• - Optically active tetrahydrofuran-2-carboxylic acid esters, such as in EP-A 0 355 561 and
• optically active 2-fluoroalkyl ethers, such as, for example, in EP-A 0 237 007, EP-A 428 720 and US-5,051,506.

Particularly preferred further components are mesogenic compounds Perfluoroalkyl or Perfluoroxalkyl fragment, such as. B. in Ferroelectrics 1988, 85, 375-384; US 4,886,619; 5,082,587; 5,254,747; 5,262,082; 5,437,812 or 5,482,650.

Very particularly preferred further mesogenic compounds with partially or perfluorinated side chains are those of the formula (XXXV),

R (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b (-A ³ -M ³ ) _c -A ⁴ -BR _f (XXXV)

in which the symbols and indices have the following meanings:
R is

• a) hydrogen, -F, -Cl, -CF ₃ , -OCF ₃ or -CN,
• b) a straight-chain or branched alkyl radical (with or without asymmetrical carbon atom) with 1 to 20 carbon atoms, where
  • b1) one or more non-adjacent and non-terminal CH ₂ groups by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- or -Si ( CH ₃ ) ₂ - can be replaced and / or
  • b2) one or more CH ₂ groups can be replaced by -CH = CH-, -C∼C-, cyclopropane-1,2-diyl, 1,4-phenylene, 1,4-cyclohexylene or 1,3-cyclopentylene and or
  • b3) one or more H atoms can be replaced by F, CN and / or Cl and / or
  • b4) the terminal CH ₃ group can be replaced by one of the following chiral groups (optically active or racemic):
• c) BR _f .

R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ are the same or different

• a) hydrogen
• b) a straight-chain or branched alkyl radical (with or without asymmetric carbon atom) with 1 to 16 carbon atoms, where
  • b1) one or more non-adjacent and non-terminal CH ₂ groups can be replaced by -O- and / or
  • b2) one or two CH ₂ groups can be replaced by -CH = CH-,
• c) R ⁴ and R ⁵ together also - (CH ₂ ) ₄ - or - (CH ₂ ) ₅ - if they are bonded to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system;

R _f is
a straight-chain or branched partially or perfluorinated alkyl radical (with or without asymmetrical carbon atom) with 1 to 20 carbon atoms, where

• a) one or more non-adjacent and non-terminal CH ₂ or CF ₂ groups by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- or -Si (CH ₃ ) ₂ - can be replaced and / or
• b) one or more CH ₂ or CF ₂ groups by -CH = CH-, -C∼C-, cyclopropane-1,2-diyl, 1,4-phenylene, 1,4-cyclohexylene or 1,3- Cyclopentylene can be replaced;

B is
-O-, -S-, (CH ₂ ) _{n + 1} O-, -O- (CH ₂ ) _{n + 1} , (CH ₂ ) _{n + 1} S-, S- (CH ₂ ) _{n + 1} , CO - (CH ₂ ) _n -, -CO-O- (CH ₂ ) _n -, -O-CO- (CH ₂ ) _n -, -CO-S- (CH ₂ ) _n -, -S-CO- ( CH ₂ ) _n -, -CS-O- (CH ₂ ) _n -, -O-CS- (CH ₂ ) _n -, SO ₂ - (CH ₂ ) _n -, -OSO ₂ - (CH ₂ ) _n - , -CH = CH-, -C∼C-, - (CH ₂ ) _{n + 1} -, -CH = N-, -N (C _k H _{2k + 1} ) -, - (CH ₂ ) _n -N ( C _k H _{2k + 1} ) -CO-, - (CH ₂ ) _n -N (C _k H _{2k + 1} ) -SO ₂ -, -O - [(CH ₂ ) _{m + 1} -O] _l - (CH ₂ ) _n -, - [(CH ₂ ) _{m + 1} -O] _l - (CH ₂ ) _n - or a single bond;
m, n are the same or different, independently of one another, an integer from 0 to 15, k is an integer from 0 to 4 and l is an integer from 1 to 6, with the proviso that m + n ≦ 15;
M ¹ , M ² , M ³ are the same or different
-CO-O-, -O-CO-, -CO-S-, -S-CO-, -CS-O-, -O-CS-, -CS-S-, -S-CS-, -CH ₂ -O-, -O-CH ₂ -, -CH ₂ -S-, -S-CH ₂ -, -CH ₂ -CH ₂ -, -CH = CH-, -C∼C-, -CH ₂ - CH ₂ -CO-O-, -O-CO-CH ₂ -CH ₂ -, -CH = N- or a single bond;
A ¹ , A ² , A ³ , A ⁴ are the same or different 1,4-phenylene, one or more H atoms being substituted by F, Cl, CH ₃ , C ₂ H ₅ , OCH ₃ , CF ₃ , OCF ₃ and / or CN can be replaced, 1,3-phenylene, where one or two CH groups can be replaced by N, pyrazine-2,5-diyl, where one or two H atoms are replaced by F, Cl and / or CN can be pyridazine-3,6-diyl, where one or two H atoms can be replaced by F, Cl and / or CN, pyridine-2,5-diyl, where one or more H atoms can be replaced by F, Cl and / or CN can be replaced, pyrimidine-2,5-diyl, where one or two H atoms can be replaced by F, Cl and / or CN, 1,4-cyclohexylene, where one or two H atoms can be replaced by CN and / or CH ₃ and / or F can be replaced, (1,3,4) thiadiazole-2,5-diyl, 1,3-dioxane-2,5-diyl, 1,3-dithiane-2,5- diyl, 1,3-thiazole-2,4-diyl, where one H atom can be replaced by F, Cl and / or CN, 1,3-thiazole-2,5-diyl, one H atom by F , Cl and / or CN can be replaced, thiophene-2,4-diyl, where a H atom can be replaced by F, Cl and / or CN, thiophene-2,5-diyl, it being possible for one or two H atoms to be replaced by F, Cl and / or CN, naphthalene-2,6-diyl, Naphthalene-1,4-diyl or naphthalene-1,5-diyl, where one or more H atoms can be replaced by F, Cl and / or CN and / or one or two CH groups can be replaced by N, Phenanthrene-2,7-diyl or 9,10-dihydrophenanthrene-2,7-diyl, where in each case one, two or more H atoms can be replaced by F and / or one or two CH groups can be replaced by N, Indan-2,5-diyl, indan-1-one-2,5-diyl, benzothiazole-2,6-diyl, benzothiazole-2,5-diyl, benzoxazole-2,6-diyl, benzoxazole- 2,5- diyl, benzofuran-2,5-diyl, benzofuran-2,6-diyl, 2,3-dihydrobenzofuran-2,5-diyl, piperazine-1,4-diyl, piperazine-2,5-diyl, 1-alkyl- 1-silacyclohexylene-1,4-diyl or 1,3-dioxaborinane-2,5-diyl;
a, b, c are zero or one,
with the proviso that the compound of formula (XXXV) may not contain more than four, preferably at least two, five or more-membered ring systems.

The mixtures containing (I) in turn can be used in electro-optical or completely optical elements, e.g. B. display elements, Switching elements, light modulators, elements for image processing and / or Signal processing or in general in the field of non-linear optics.

Furthermore, the mixtures containing (I) for field treatment, i. H. to operate in Quasi-Bookshelf Geometry (QBG) (see e.g. H. Rieger et al., SID 91 Digest (Anaheim) 1991, 396).

Furthermore, the mixtures containing (I) are particularly suitable for operation in the so-called "spontaneous bookshelf geometry". The mixtures containing (I) are also suitable for operation in the so-called inverse or τV _(min) mode (see, for example: JC Jones, MJ Towler, JR Hughes, Displays 1993, 14, No. 2, 86-93 ; M. Koden, Ferroelectrics 1996, 179, 121-129).

Liquid-crystalline mixtures, the compounds of the general formula (I) included, are especially for use in electro-optical switching and Suitable display devices. These displays are usually like this built up that a liquid crystal layer is enclosed on both sides by layers which is usually, in this order, starting from the LC layer, at least one orientation layer, electrodes and a boundary disk (e.g. made of glass). You can also use spacers, for example Adhesive frames, polarizers and thin color filter layers for color displays contain. Other possible components are anti-reflective, passivation, Compensating and barrier layers as well as electrical nonlinear elements, such as Thin film transistors (TFT) and metal insulator metal (MIM) elements. In detail is the structure of liquid crystal displays in relevant monographs (see, for example, E. Kaneko, "Liquid Crystal TV Displays: Principles and Applications of Liquid Crystal Displays ", KTK Scientific Publishers, 1987).  

Another object of the invention is therefore a switching and / or Display device, in particular a ferroelectric, containing one Liquid crystal mixture which contains one or more compounds of the formula (I).

The switching and / or display device according to the invention is preferably in the Normal mode or operated using the "spontaneous bookshelf geometry".

Such devices can be used, for example, as computer displays or in Find smart card application.

example 1

4- (5-decyl-pyrimidin-2-yl) phenyl (perfluorocyclohexyl) methyl ether

A solution of 4- (5-decyl-pyrimidin-2-yl) phenol in methyl ethyl ketone is added Add three times the molar amount of potassium carbonate with 1.2 times the molar amount (Perfluorocyclohexyl) methyl-toluenesulfonic acid ester heated to reflux temperature. The solvent is distilled off in vacuo and the residue under intense Stir in a two-phase mixture of dichloromethane / water. The organic Phase is separated, the aqueous extracted again with dichloromethane and the combined organic phases of a chromatography (silica gel / Dichloromethane). By recrystallization from acetonitrile one can further cleaning can be achieved.  

Example 2

2- (4-hexylphenyl) -5-perfluorocyclohexyl- (1,3,4) thiadiazole

A solution of 1- (4-hexylbenzoyl) hydrazine in pyridine is added in portions at 10 ° C with the equimolar amount of perfluorocyclohexylcarboxylic acid fluoride. After 5 h at room temperature is poured onto five times the amount of water, with HCl adjusted to pH 5 to 6 and extracted with dichloromethane. The resulting Diacylhydrazine is, if necessary after purification (low-temperature crystallization from acetonitrile), with the stoichiometric amount of Lawesson's reagent for 10 h in Tetrahydrofuran heated to reflux. It is evaporated to half in vacuo and poured the residue into five times the amount of water. By adding 10 N aqueous NaOH is adjusted to pH 8 and extracted three times with dichloromethane. The combined extracts are concentrated in vacuo and one subjected to chromatographic purification (silica gel, dichloromethane); the The final product can be further purified by recrystallization from acetonitrile.

Example 3

4'-heptyl-2, '3'-difluoro-biphenyl-perfluorocyclohexane carboxylic acid ester

A solution of 4'-heptyl-2 ', 3'-difluoro-4-hydroxy-biphenyl and the 1.1-fold molar Amount of triethylamine in tetrahydrofuran is added in portions at -20 ° C with the equimolar amount of perfluorocyclohexylcarboxylic acid fluoride added. After finished  Addition is stirred for a further 1 h at this temperature and slowly opened with stirring Brought to room temperature. Triethylammonium hydrochloride is filtered off and that Filtrate brought to dryness in a vacuum. The residue becomes a chromatography (Silica gel, dichloromethane). The product can be recrystallized can also be cleaned from acetonitrile.

Example 4

4- (5-octyl-1,3-dioxan-2-yl) phenyl-perfluorocyclohexane carboxylic acid ester

is prepared analogously to Example 3 from 4- (5-octyl-1,3-dioxan-2-yl) phenol.

Example 5

1- (4'-Pentyl-biphenyl-4-yl) -2-perfluorocyclohexyl-ethane

A solution of 4-formyl-4'-pentyl-biphenyl (made from the commercial available 4'-pentyl-4-bromo-biphenyl by reaction with magnesium Grignard compound and reaction of the latter with dimethylformamide) in Tetrahydrofuran becomes a reacted mixture of at room temperature (Perfluorocyclohexyl) methyltriphenylphosphonium bromide (made from the commercially available (perfluorocyclohexyl) methanol by reaction with Phosphorus tribromide and reaction of (perfluorocyclohexyl) methyl bromide with Triphenylphosphine in toluene at 100 ° C) and K-tert-butoxide in tetrahydrofuran  dripped. When the reaction has ended, the pH is adjusted to three times with HCl, three times Volume of water added and extracted three times with dichloromethane. The combined organic phases are brought to dryness in vacuo and the Residue of a chromatographic purification (silica gel, dichloromethane) subjected. By hydrogenation in tetrahydrofuran (room temperature, normal pressure, 10% by weight Pd / C (10%)) the target compound is obtained; by chromatography (Silica gel, dichloromethane) and recrystallization from acetonitrile can be a purification respectively.

Example 6

4- (4-trans-pentylcyclohexyl) phenyl (perfluorocyclohexyl) methyl ether

is analogous to Ex. 1 made from 4- (4-trans-pentyl- cyclohexyl) phenol.

Claims (10)

1. polyfluorinated cyclohexane derivative of the formula (I),
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b (-A ³ ) _c -M ³ -B (I)
where the symbols and indices have the following meanings:
B is perfluorocyclohexyl (C ₆ F ₁₁ ), hereinafter with the formula:
designated
R ¹ is

• a) Hydrogen, -OCF ₃ , -CF ₃ , -CN, -F, -Cl, -OCHF ₂ , -OCH ₂ F, -CHF ₂ or -CH ₂ F
• b) a straight-chain or branched alkyl radical (with or without asymmetrical carbon atom) with 1 to 20 carbon atoms, where
  • b1) one or more non-adjacent and non-terminal CH ₂ groups by -O-, -S-, -CO-O-, -O-CO-, -O-CO-O- or -Si (CH ₃ ) ₂ - can be replaced and / or
  • b2) one or more CH ₂ groups can be replaced by -CH = CH-, -C∼C-, cyclopropane-1,2-diyl, 1,4-phenylene, 1,4-cyclohexylene or 1,3-cyclopentylene and or
  • b3) one or more H atoms can be replaced by F and / or Cl and / or
    b4) the terminal CH ₃ group can be replaced by one of the following chiral groups (optically active or racemic):

R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ are the same or different

• a) hydrogen
• b) a straight-chain or branched alkyl radical (with or without asymmetric carbon atom) with 1 to 16 carbon atoms, where
  
  • b1) one or more non-adjacent and non-terminal CH ₂ groups can be replaced by -O- and / or
  • b2) one or two CH ₂ groups can be replaced by -CH = CH-,
• c) R ⁴ and R ⁵ together also - (CH ₂ ) ₄ - or - (CH ₂ ) ₅ - if they are bonded to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system;

M ¹ , M ² are the same or different -CO-O-, -O-CO-, -CO-S-, -S-CO-, -CS-O-, -CS-S-, -O-CS -, -S-CS-, -CH ₂ -O-, -O-CH ₂ -, -CH ₂ -S-, -S-CH ₂ -, -CH = CH-, -C∼C-, -CH ₂ -CH ₂ -CO-O-, -O-CO-CH ₂ -CH ₂ - or a single bond;
M ³ is -O-CO-, -O-CH ₂ -, -CH = CH-, - CH ₂ -CH ₂ -, -CH ₂ -CH ₂ -OCH ₂ -, - CH ₂ - CH ₂ -OC ( = O) -, -CH ₂ -CH ₂ -CH = CH-, -CH ₂ -CH ₂ -CH ₂ -CH ₂ - or, if the index is c 1, a single bond
A ¹ , A ² , A ³ are identical or different 1,4-phenylene, where one or more H atoms can be replaced by F, Cl and / or CN, pyrazine-2,5-diyl, one or two H -Atoms can be replaced by F, Cl and / or CN, pyridazine-3,6-diyl, where one or two H atoms can be replaced by F, Cl and / or CN, pyridine-2,5-diyl, where one or more H atoms can be replaced by F, Cl and / or CN, pyrimidine-2,5-diyl, where one or two H atoms can be replaced by F, Cl and / or CN, 1,4-cyclohexylene , where one or two H atoms can be replaced by CN and / or CH ₃ and / or F, (1,3,4) -Thiadiazol-2,5-diyl, 1,3-dioxane-2,5-diyl , 1,3-dithiane-2,5-diyl, 1,3-thiazole-2,4-diyl, where an H atom can be replaced by F, Cl and / or CN, 1,3-thiazole-2, 5-diyl, where an H atom can be replaced by F, Cl and / or CN, thiophene-2,4-diyl, where an H atom can be replaced by F, Cl and / or CN, thiophene-2, 5-diyl, where one or two H atoms by F, Cl and / or CN may be replaced, naphthalene-2,6-diyl, naphthalene-1,4-diyl or naphthalene-1,5-diyl, it being possible for one or more H atoms to be replaced by F, Cl and / or CN and / or one or two CH groups can be replaced by N, phenanthrene-2,7-diyl or 9,10-dihydrophenanthrene-2,7-diyl, where one, two or more H atoms can be replaced by F and / or one or two CH groups can be replaced by N, indan-2,5-diyl, indan-1-one-2,5-diyl, benzothiazole-2,6-diyl, benzothiazole-2,5-diyl, benzoxazole 2,6-diyl, benzoxazole-2,5-diyl, benzofuran-2,5-diyl, benzofuran-2,6-diyl, 2,3-dihydrobenzofuran-2,5-diyl, piperazine-1,4-diyl, Piperazine-2,5-diyl or 1,3-dioxaborinane-2,5-diyl;
a, b, c are 0 or 1, with the proviso that the compound of formula (I) contains at least two and not more than four five- or more-membered ring systems. 2. Polyfluorinated cyclohexane derivative according to claim 1, wherein the symbols and indices in the formula (I) have the following meanings:
R ¹

• a) hydrogen,
• b) a straight-chain or branched alkyl radical (with or without asymmetrical carbon atom) with 1 to 18 carbon atoms, where
  
  • b1) one or more non-adjacent and non-terminal CH ₂ groups can be replaced by -O-, -CO-O-, -O-CO-, -O-CO-O or -Si (CH ₃ ) ₂ - and /or
  • b2) a CH ₂ group can be replaced by cyclopropane-1,2-diyl, 1,4-phenylene or trans-1,4-cyclohexylene and / or
  • b3) one or more H atoms can be replaced by F and / or
  • b4) the terminal CH ₃ group can be replaced by one of the following chiral groups (optically active or racemic):

R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ are the same or different

• a) hydrogen
• b) a straight-chain or branched alkyl radical (with or without an asymmetric carbon atom) with 1 to 14 carbon atoms, where
  • b1) one or two non-adjacent and non-terminal CH ₂ groups can be replaced by -O- and / or
  • b2) a CH ₂ group can be replaced by -CH = CH-,
• c) R ⁴ and R ⁵ together also - (CH ₂ ) ₄ - or - (CH ₂ ) ₅ - if they are bonded to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system;

M ¹ , M ² , are the same or different -CO-O-, -O-CO-, -CH ₂ -O-, -O-CH ₂ -, -CH = CH-, -C∼C-, -CH ₂ -CH ₂ -CO-O-, -O-CO-CH ₂ -CH ₂ - or a single bond;
M ³ is -O-CO-, -OCH ₂ -, -CH ₂ -CH ₂ -, -CH ₂ -CH ₂ -CH ₂ -CH ₂ - or a single bond;
A ¹ , A ² , A ³ are identical or different 1,4-phenylene, where one or two H atoms can be replaced by F and / or CN, pyridine-2,5-diyl, one or two H atoms can be replaced by F and / or CN, pyrimidine-2,5-diyl, where one or two H atoms can be replaced by F, trans-1,4-cyclohexylene, where one or two H atoms by CN and / or CH ₃ and / or can be replaced, (1,3,4) thiadiazole-2,5-diyl, 1,3-dioxane-2,5-diyl, 1,3-thiazole-2,4-diyl, where an H atom can be replaced by F and / or CN or 1,3-thiazole-2,5-diyl, where an H atom can be replaced by F and / or CN, thiophene-2,5-diyl, where one or two H atoms can be replaced by F and / or CN;
a, b, c are 0 or 1; with the proviso that the compound of formula (I) contains at least two and not more than four five or more-membered ring systems. 3. Polyfluorinated cyclohexane derivative according to claim 1 and / or 2, wherein the symbols and indices in the formula (I) have the following meanings:
R ¹ is

• b) a straight-chain or branched alkyl radical (with or without asymmetrical carbon atom) with 1 to 16 carbon atoms, where
  • b1) one or two non-adjacent and non-terminal CH ₂ groups can be replaced by -O-, -CO-O-, -O-CO-, -O-CO-O- or -Si (CH ₃ ) ₂ - and or
  • b2) a CH ₂ group can be replaced by 1,4-phenylene or trans-1,4-cyclohexylene and / or
  • b3) one or more H atoms can be replaced by F and / or
  • b4) the terminal CH ₃ group can be replaced by one of the following chiral groups (optically active or racemic):

R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ are the same or different

• a) hydrogen
• b) a straight-chain or branched alkyl radical (with or without an asymmetric carbon atom) with 1 to 14 carbon atoms, where
  • b1) a non-terminal CH ₂ group can be replaced by -O- and / or
• c) R ⁴ and R ⁵ together also - (CH ₂ ) ₄ - or - (CH ₂ ) ₅ - if they are bonded to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system;

M ¹ , M ² are identical or different -CO-O-, -O-CO-, -CH ₂ -O-, -O-CH ₂ - or a single bond;
A ¹ , A ² , A ³ are identical or different 1,4-phenylene, where one or two H atoms can be replaced by F, pyridine-2,5-diyl, where one H atom can be replaced by F, Pyrimidine-2,5-diyl, trans-1,4-cyclohexylene, where one or two H atoms can be replaced by CN and / or CH ₃ and / or F;
a, b, c, d are 0 or 1; with the proviso that the compound of formula (I) contains no more than four five or more membered ring systems. 4. Polyfluorinated cyclohexane derivative according to one or more of claims 1 to 3, selected from the group (Ia) - (It):
in which mean:
R ^{8 is} a straight-chain or branched alkyl chain with 1 to 19 C atoms, it being possible for one or two H atoms on adjacent C atoms to be replaced by F and / or one or more —CH ₂ - groups by the —CF ₂ groups and one or two non-adjacent -CH ₂ groups can also be replaced by -O- and / or -OC (= O) -;
R ^{9 is} a straight-chain alkyl chain of 1 to 12 carbon atoms;
X, Y the same or different H or F. 5. Use of polyfluorinated cyclohexane derivatives according to one or several of claims 1 to 4 as components of liquid-crystalline mixtures. 6. Liquid crystal mixture containing one or more polyfluorinated Cyclohexane derivatives according to one or more of claims 1 to 4. 7. Liquid crystal mixture according to claim 6, characterized in that it optically active, inclined smectic. 8. Liquid crystal mixture according to claim 6 or 7, characterized in that that they 0.01 to 80 wt .-% of one or more polyfluorinated Contains cyclohexane derivatives of the formula (I). 9. switching and / or display device containing an optically active inclined smectic liquid crystal mixture according to claim 7 or 8. 10. Switching and / or display device according to claim 9, characterized characterized in that the liquid crystal mixture is a spontaneous bookshelf geo has metry.