DE19907063A1 - New fluorinated thiophene derivatives useful as components of liquid crystal mixtures for use in switching and display devices - Google Patents

Abstract

Fluorinated thiophene derivatives (I) are new. Fluorinated thiophene derivatives of formula (I) are new: R<1>, R<2> = H or Q, but not both H; Q = 1-20C alkyl in which (a) one or two nonterminal CH2 groups can be replaced by O and/or CO or SiMe2, provided that two adjacent CH2 groups are not replaced by heteroatoms, (b) one or more CH2 groups can be replaced by CH=CH and/or ethynylene, (c) one CH2 group can be replaced by 1,2-cyclopropylene, 1,3-cyclobutylene, 1,4-cyclopentylene, 1,3-bicyclo(1.1.1)pentylene, 1,4-cyclohexylene or 1,4-phenylene, optionally mono- or disubstituted by F, (d) one or more H atoms can be replaced by H and/or (e) an asymmetric C atom can be substituted by Me, OMe, CF3, F, CN or Cl or form part of a 3- to 7-membered ring in which one or two nonadjacent CH2 groups can be replaced by O and one CH2 group can be replaced by OC(O); A<1>-A<3> = 1,4-phenylene optionally mono- or disubstituted by CN or F; 1,3-phenylene optionally mono- or disubstituted by CN or F; 1,4-cyclohexylene optionally substituted by CN, F or Me; 2,5-pyridinediyl optionally monosubstituted by F; 2,5-pyrimidinediyl optionally monosubstituted by F; 1,3-dioxane-2,5-diyl optionally monosubstituted by CN; or 2,6-naphthylene; X<1>, X<2> = H or F, but not both H; M = OC(O), OCH2, OC(O)CH2CH2, O(CH2)3, CH2CH2, ethynylene, (CH2)4 or a bond; n, m = 0 or 1, but not both 0. Independent claims are also included for the following: (1) a liquid crystal mixture containing one or more compounds (I); (2) a switching and/or display device containing the liquid crystal mixture of (1).

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 for 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. EP-A 0 032 362). Because of this and others cheaper Properties, e.g. B. the bistable switching option and almost angle-independent contrast, FLCs are basically for use areas such as computer displays are well suited.

For a more in-depth discussion of the technical requirements for FLCs, go to referred to DE-A 197 48 432.

Sulfur-containing heterocycles have already been described for use in liquid crystal mixtures:
Thiophene derivatives e.g. B. in DE-A 33 46 175, (1,3,4); -Thiadiazole derivatives z. B. in US 5,200,109; (1,3) -Thiazole derivatives e.g. In EP-A-0 309 514; Benzothiazole derivatives z. B. in JP-A 09059266.

Fluorinated nitrogen heterocycles are also described as components of liquid-crystalline mixtures:
4-fluoropyrimidine derivatives e.g. B. in US 5,344,585, fluorinated pyridine derivatives z. B. in US 5,389,291; 2-fluoropyrazine derivatives e.g. B. in US 5,562,859.

3-fluoro-5-phenylthiophene is e.g. B. from Rodmar, Swed. Mol. Phys. (1971), 22 (1), 123-35 [CAN 75: 145500] and Gronowitz et al., Chem. Scr. (1971), 1 (1), 33-43 [CAN 75: 20080] known; a suitability of 3- or 4-fluoro-thiophenes as Components of liquid crystalline mixtures are not suitable for these two works remove.

As the development, especially of ferroelectric liquid crystal mix conditions that can in no way be considered complete are the Manufacturer of displays on a wide variety of components for mixtures interested, among other things, because only the interaction of the rivers sigcrystalline mixtures with the individual components of the display device or the cells (e.g. the orientation layer) draw conclusions about the quality also allows the liquid crystalline mixtures.

It has now been found that fluorinated thiophenes of the formula (I) are already present in low admixing quantities the properties of liquid crystal mixtures, especially chiral-smectic mixtures, favorably affect, for. B. in terms of dielectric anisotropy and / or melting point, however also with regard to the switching behavior.

The invention therefore relates to fluorinated thiophenes of the formula (I)

where the symbols and indices have the following meanings:
R ¹ , R ² are the same or different
Hydrogen or a straight-chain or branched alkyl radical (with or without asymmetrical carbon atoms) with 1 to 20 carbon atoms, where

• a) one or two non-terminal CH ₂ groups can be replaced by -O- and / or -C (= O) - or -Si (CH ₃ ) ₂ - with the proviso that two adjacent -CH ₂ groups cannot can be replaced by heteroatoms and / or
• b) one or more CH ₂ groups can be replaced by -CH = CH- and / or -C∼C- and / or
• c) a CH ₂ group by cyclopropane-1,2-diyl, cyclobutane-1,3-diyl, cyclopentane-1,4-diyl, bicyclo [1.1.1] pentane-1,3-diyl, cyclohexane-1, 4-diyl or phenylene-1,4-diyl, optionally mono- or disubstituted by F, can be replaced and / or
• d) one or more H atoms can be replaced by F and / or
• e) in the case of a branched alkyl radical having asymmetric carbon atoms, the asymmetric carbon atoms either have -CH ₃ -, -OCH ₃ , -CF ₃ , F, CN or Cl as substituents or are part of a 3- to 7-membered ring , in which 1 or 2 non-adjacent -CH ₂ groups can also be replaced by -O- and one -CH ₂ - group by -OC (= O) -,

with the proviso that R ¹

, R ²

should not mean hydrogen at the same time.
A ¹

, A ²

, A ³

are the same or different
Phenylene-1,4-diyl, optionally mono- or disubstituted by CN or F, phenylene-1,3-diyl, optionally mono- or disubstituted by CN or F, cyclohexane-1,4-diyl, optionally monosubstituted by CN, F or CH ₃

, Pyridine-2,5-diyl, optionally monosubstituted by F, pyrimidine-2,5-diyl, optionally monosubstituted by F, 1,3-dioxane-2,5-diyl, optionally monosubstituted by CN, naphthalene-2 6-diyl
X ¹

, X ²

independently of one another H or F, but at least one of X ¹

and X ²

is F
M undirected -OC (= O) -, -OCH ₂

-, -OC (= O) CH ₂

CH ₂

-, -OCH ₂

CH ₂

CH ₂

- -CH ₂

-CH ₂

-, -C∼C-, -CH ₂

CH ₂

CH ₂

CH ₂

- or a single bond
m, n independently of one another zero or 1, m + n but at least 1.

The expression "non-directional" means that the bridging oxygen atoms can be bound to A ² or A ³ .

The expression "not terminal" in a) means that no terminal CH ₃ group can be replaced. However, the CH ₂ group connecting A ¹ , thiophene, A ² or A ³ can be replaced.

The symbols and indices in the formula (I) preferably have the following meanings:
R ¹ , R ² are preferably the same or different
a straight-chain or branched alkyl radical (with or without asymmetrical carbon atoms) with 2 to 18 carbon atoms, where

• a) a CH ₂ group can be replaced by -O- and / or
• b) one or more H atoms can be replaced by F.

R ¹

, R ²

are particularly preferably identical or different to a straight-chain or branched alkyl radical (with or without asymmetrical carbon atoms) having 3 to 16 carbon atoms, where

• 1. a CH ₂ group can be replaced by -O-.

A ¹

, A ²

, A ³

are preferably identical or different phenylene-1,4-diyl, optionally mono- or disubstituted by F, phenylene-1,3-diyl, optionally mono- or disubstituted by F, cyclohexane-1,4-diyl.
A ¹

, A ²

, A ³

are particularly preferred phenylene-1,4-diyl.
n is preferably -CH ₂

-CH ₂

-, -C∼C-, undirected -OC (= C) - or a single bond.
m + n is preferably 1.

The following compounds of the formulas (I-1) to (I- 7) are particularly preferred:

wherein R ¹ and R ^{2 have} the meanings and preferences given above; in the case of the compounds (I-7), R ¹ and R ² are particularly preferably identical.

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

However, it may prove necessary to vary or modify the literature methods for the requirements of mesogenic building blocks, since e.g. B. functional derivatives with long (<C ₆ ) alkyl chains often show less reactivity than z. B. the methyl or ethyl analogs.

In this context, reference is made in particular to the following references, in which the synthesis of suitable thiophene derivatives or precursors or starting materials which are required for their preparation is described:
Literature 1: Gotthardt et al., Chem. Ber. (1976), 109 (2), 740-52 [CAN 84: 135558] for the synthesis of mesoionic 1,3-dithiolones
Literature 2: Gotthardt et al., Ibid. (1976), 109 (2), 753-60 [CAN 84: 179952] for the synthesis of thiophene-3,4-dicarboxylic acids or thiophene-3-carboxylic acids from mesoionic 1,3-dithiolones
Literature 3: Forrest et al., Tetrahedron Lett., 36, 2117 (1995) [CAN 122: 314390] for fluorodecarboxylation
Literature 4: Wang et al., J. Chem. Soc., Chem. Comm., 2399 (1995) [CAN 124: 145805] for fluorodecarboxylation
Literature 5: Banks et al., J. Fluorine Chem. (1998), 87 (1), 1-17 [CAN 128: 216948]) for F-TEDA-BF ₄
Literature 6: Gronowitz et al., Chem. Scr. (1971), 1 (1), 33-43 [CAN 75: 20080] for the synthesis of 3-fluoro-thiophene building blocks, e.g. B. 2,5-dibromo-3-fluorothiophene
Literature 7: Christiansen et al., Ark. Kemi (1969), 30 (55), 561 [CAN 71: 26413] for the synthesis of 3,4-difluorothiophene

What about linking functional derivatives of fluorinated thiophenes with With regard to other liquid crystal-specific building blocks, it is expressly stated on DE-A 197 48 432, in which a listing more familiar to a person skilled in the art Methods is specified.  

The invention also relates to the use of compounds of For mel (I) in liquid crystal mixtures, preferably smectic and nematic, particularly preferably ferroelectric liquid crystal mixtures. In particular preferred is the use in ferroelectric liquid crystal mixtures which operated in inverse mode or in displays with active matrix elements.

The invention furthermore relates to liquid crystal mixtures, preferably smectic and nematic, 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) according to the invention.

Other components of liquid crystal mixtures, the invention Compounds of formula (I) are preferably selected from the known compounds with smectic and / or nematic and / or chole steric phases. In this sense, other suitable mixture components are particularly so in the international patent application PCT / EP 96/03154 as listed in DE-A 197 48 432, to which express reference is hereby made becomes.

The mixtures according to the invention can in turn 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.  

Another object of the invention is therefore a switching and / or Display device, preferably a smectic or nematic switching and / or display device containing a liquid crystal mixture, the one or contains more compounds of formula (I).

Ferroelectric switching and / or display devices which operate in normal or inverse (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).

Also particularly preferred are ferroelectric switching and / or Display devices that contain active matrix elements (see, for example, DE-A 198 22 830).

Various documents are cited in the present application, for example to explain the technical environment of the invention. To all these documents are hereby expressly referred to; they apply through Quotation as part of the present application.

The invention is further illustrated by the following examples without it wanting to restrict it.

example 1 3-fluoro-2,5-bis (4-nonylphenyl) thiophene

A suspension of equimolar amounts of 2,5-bis (4-nonylphenyl) thiophene (produced by Suzuki coupling of 2,5-dibromothiophene with 4-nonyl phenylboronic acid; mp. 138-140 ° C) and F-TEDA-BF ₄ [ 140681-55-6] in acetonitrile is stirred for 24 h at room temperature. It is poured into ten times the amount of water and extracted twice with 100 ml of dichloromethane. The combined organic phases are dried and evaporated in vacuo.

The residue is subjected to chromatographic purification (silica gel, heptane) and a subsequent recrystallization (from acetonitrile). The product shows the characteristic signals in ¹ H-NMR (400 MHz, CDCl ₃ ) at δ = 7.57 (d, 2H), 7.48 (d, 2H), 7.23 - 7.18 (2 * d , 4H) and 7.05 (s, 1H) ppm and in ¹⁹ F-NMR (376.5 MHz, CDCl ₃ ) the characteristic signal at δ = -128 ppm; Phase sequence X 51 S _A 76 l.

Example 2 3,4-difluoro-2,5-bis (4-hexylphenyl) thiophene

2,5-bis (4-hexylphenyl) thiophene-3,4-dicarboxylic acid {accessible by cycloaddition analogous to literature 2 by reaction of 2,5-bis (4-hexylphenyl) -1,3-dithiol-4-one (Synthesis analogous to literature 1) with dimethyl acetylenedicarboxylate [762-42-5]} is subjected to fluorodecarboxylation (analogous to literature 3) using F-TEDA-BF ₄ [140681-55-6]; the crude product is purified by chromatography.

Example 3 3,4-difluoro-2- (4-hexylphenyl) -5- (4-hexyloxyphenyl) thiophene

Analogous to example 2, but using 2- (4-hexylphenyl) -5- (4- methoxyphenyl) thiophene-3-carboxylic acid [accessible analogously to literature 2 through Reaction of 2- (4-hexylphenyl) -5- (4-methoxyphenyl) -1,3-dithiol-4-one (Synthesis analogous to literature 1) with dimethyl acetylenedicarboxylate], Difluoro-2- (4-hexylphenyl) -5- (4-methoxyphenyl) thiophene obtained. By Ether cleavage (for example with hydrobromic acid-acetic acid) to 3,4- Difluoro-2- (4-hexylphenyl) -5- (4-hydroxyphenyl) thiophene and Mitsunobu- Reaction with hexanol is the result after chromatographic purification and Recrystallization from acetonitrile the target compound available.

As in Example 1-3, other representatives of the connection class (I-1) be preserved.  

Example 4

3,4-difluoro-5-butyl-2- (4-octyloxyphenyl) thiophene is obtained analogously to Example 3, but using S-butyl-2- (4- methoxyphenyl) -1,3-dithiol-4-one in the cycloaddition step.

The classes of compounds (I-4), (I-5) and (I-6) can be obtained analogously.

Example 5

3,4-difluoro-5-butyl-2- (4-pentyl-biphenyl-4'-yl) thiophene is obtained analogously to Example 3, but using 2- (4-bromophenyl) -5- butyl-1,3-dithiol-4-one in the cycloaddition step. That after Fluorodecarboxylation obtained 2- (4-bromophenyl) -5-butyl-3,4-difluoro-thiophene becomes the target compound in a Suzuki coupling with 4-pentylphenylboronic acid implemented.

The connection classes (I-2) and (I-3) can be obtained analogously.

Example 6

3-fluoro-2,5-bis (4-hexylphenyl) thiophene is obtained analogously to Example 2, but in the stage of cycloaddition Pro methyl fiol acid [922-67-8] instead of dimethyl acetylenedicarboxylic acid is used.

Analogously, further representatives of the compound classes (I-7) can be obtained.

Claims (13)

1. fluorinated thiophene derivatives of the formula (I),
where the symbols and indices have the following meanings:
R ¹ , R ² are the same or different
Hydrogen or a straight-chain or branched alkyl radical (with or without asymmetrical carbon atoms) with 1 to 20 carbon atoms, where

• a) one or two non-terminal CH ₂ groups can be replaced by -O- and / or -C (= O) - or -Si (CH ₃ ) ₂ - with the proviso that two adjacent -CH ₂ groups cannot can be replaced by heteroatoms and / or
• b) one or more CH ₂ groups can be replaced by -CH = CH- and / or -C∼C- and / or
• c) a CH ₂ group by cyclopropane-1,2-diyl, cyclobutane-1,3-diyl, cyclopentane-1,4-diyl, bicyclo [1.1.1] pentane-1,3-diyl, cyclohexane-1, 4-diyl or phenylene-1,4-diyl, optionally mono- or disubstituted, can be replaced by F and / or
• d) one or more H atoms can be replaced by F, and / or
• e) in the case of a branched alkyl radical having asymmetric carbon atoms, the asymmetric carbon atoms either have -CH ₃ , -OCH ₃ , -CF3, F, CN or Cl as substituents or are part of a 3- to 7-membered ring, in which 1 or 2 non-adjacent -CH ₂ groups can also be replaced by -O- and one -CH ₂ group by -OC (= O) -,

with the proviso that R ¹ , R ² should not simultaneously be hydrogen,
A ¹ , A ² , A ³ are identical or different phenylene-1,4-diyl, optionally mono- or disubstituted by CN or F, phenylene-1,3-diyl, optionally mono- or disubstituted by CN or F, Cyclohexane-1,4-diyl, optionally monosubstituted by CN, F or CH ₃ , pyridine-2,5-diyl, optionally monosubstituted by F, pyrimidine-2,5-diyl, optionally monosubstituted by F, 1,3 -Dioxane-2,5-diyl, optionally monosubstituted by CN, naphthalene-2,6-diyl,
X ¹ , X ^{2 are} independently H or F, but at least one of X ¹ and X ² is F
M undirected -OC (= O) -, -OCH ₂ -, -OC (= O) CH ₂ CH ₂ -, OCH ₂ CH ₂ CH ₂ - -CH ₂ CH ₂ -, -C∼C-, -CH ₂ CH ₂ CH ₂ CH ₂ - or a single bond
m, n independently of one another zero or 1, m + n but at least 1. 2. Fluorinated thiophene derivatives according to claim 1, which correspond to the formula (I-1)
in which R ¹ , R ^{2 represent} a straight-chain or branched alkyl radical (with or without asymmetrical carbon atoms) having 1 to 16 carbon atoms, in which also one or two non-terminal -CH ₂ groups are denoted by -O- and / or - C (= O) - can be replaced with the proviso that two adjacent -CH ₂ groups should not be replaced by heteroatoms. 3. Fluorinated thiophene derivatives according to claim 1, which correspond to the formula (I-2)
in which mean:
R ^{1 is} a straight-chain or branched alkyl radical (with or without asymmetrical C atoms) with 1 to 16 C atoms, in which one or more H can also be replaced by F,
R ^{2 is} a straight-chain or branched alkyl radical (with or without asymmetrical carbon atoms) with 1 to 16 carbon atoms, in which also one or two non-terminal -CH ₂ groups by -O- and / or -C (= O) - can be replaced with the proviso that two adjacent -CH ₂ groups should not be replaced by heteroatoms. 4. Fluorinated thiophene derivatives according to claim 1, which correspond to the formula (I-3)
in which mean:
R ^{1 is} a straight-chain or branched alkyl radical (with or without asymmetrical C atoms) with 1 to 16 C atoms, in which one or more H can also be replaced by F,
R ^{2 is} a straight-chain or branched alkyl radical (with or without asymmetrical carbon atoms) with 1 to 16 carbon atoms, in which also one or two non-terminal -CH ₂ groups by -O- and / or -C (= O) - can be replaced with the proviso that two adjacent -CH ₂ groups should not be replaced by heteroatoms. 5. Fluorinated thiophene derivatives according to claim 1, which correspond to the formula (I-7)
in which mean:
R ^{1 is} a straight-chain or branched alkyl radical (with or without asymmetrical C atoms) with 1 to 16 C atoms, in which one or more H can also be replaced by F,
R ^{2 is} a straight-chain or branched alkyl radical (with or without asymmetrical carbon atoms) with 1 to 16 carbon atoms, in which also one or two non-terminal -CH ₂ groups by -O- and / or -C (= O) - can be replaced with the proviso that two adjacent -CH ₂ groups should not be replaced by heteroatoms. 6. Use of fluorinated thiophenes according to one of claims 1 to 5 as components of liquid crystalline mixtures. 7. Liquid crystal mixture containing one or more fluorinated thiophenes according to one of claims 1 to 6. 8. Liquid crystal mixture according to claim 7, characterized in that it is ferroelectric (chiral smectic). 9. Liquid crystal mixture according to claim 8, characterized in that it is nematic. 10. Liquid crystal mixture according to one of claims 7 to 9, characterized characterized in that they contain 0.01 to 80% by weight of one or more of the contains fluorinated thiophenes of the formula (I). 11. Switching and / or display device containing a liquid crystal Mixture according to one of claims 7 to 10. 12. Switching and / or display device according to claim 11, characterized in that it is operated in τV _(min) mode. 13. Switching and / or display device according to claim 11, characterized records that it contains active matrix elements.