DE19953830A1 - Novel sulfur-containing compounds such as 5-propyl-thiophene-2-carboxylic acid-(4-(5-undecyl-pyrimidine-2-yl)-phenyl)-thioester are useful as dopants for improving the properties of liquid crystal mixtures - Google Patents

Abstract

Sulfur-containing compounds with a heterocyclic group and/or a cyclic hydrocarbon group are new. Sulfur-containing compounds of formula (I) with a heterocyclic group and/or a cyclic hydrocarbon group are new, where T = cyclohexane-1,4-diyl; Y = -SC(O)-; A<3> = phenylene-1,4-diyl; X = -O- or a bond; and R<1> and R<2> = 1-10C alkyl being excluded. T = thiophene-2,4- or 2,5-diyl (optionally monosubstituted by F), cyclohexane-1,4-diyl (optionally monosubstituted Me, CN or F), cyclohex-1- or -2-ene-1,4-diyl, 1-alkyl-1-silacyclohexane-1,4-diyl, cyclopentane-1,3-diyl, furane-2,4- or 2,5-diyl, thiazole-2,4- or 2,5-diyl or 1,3-dioxane-2,5-diyl (optionally monosubstituted by CN or F); R<1> = H, 1-20C alkyl or 2-20C alkenyl (optionally with asymmetric C atoms) such that (a) 1 or 2 non-terminal and non-adjacent CH2 groups can be replaced by -O- or -C(O)-; (b) one -CH2- group can be replaced by -C equivalent to C-, -Si(Me)2, cyclopropane-1,2-diyl, cyclobutane-1,3-diyl, cyclopentane-1,4-diyl, bicyclo(1.1.1)pentane-1,3-diyl and/or cyclohexane-1,4-diyl; (c) one or more H can be replaced by F and/or CN; and/or (d) any asymmetric C atoms in the alk(en)yl groups can be substituted by Me, OMe, CF3, F, CN and/or Cl or can be in a 3- to 7-membered ring, with 1 or 2 non-adjacent -CH2 groups optionally replaced by -O- and a non-adjacent -CH2- group also optionally replaced by -OC(O)-; R<2> = H, 1-20C alkyl or 2-20C alkenyl (optionally with asymmetric C atoms) optionally with a non-terminal -CH2- group replaced by -O-, -OC(O)- or -C(O)O- and/or with 1 or more H replaced by F and such that (a) the Z-linked -CH2- group cannot be replaced by -O- when Z = -O- and (b) R<2> can only be H when Z = a bond and R<1> is not H; X = a bond, -O-, -OC(O)-, -C(O)O- or -OC(O)O-; Y = -SC(O)- or -SCH2-; Z = a bond or -O-; A<1> - A<3> = phenylene-1,3- or 1,4-diyl (optionally substituted once or twice by CN or F), cyclohexane-1,4-diyl (optionally with 1 or 2 H replaced by CN, Me or F), 1-cyclohexene-1,4-diyl (optionally with 1 H replaced by F), 1-alkyl-1-silacyclohexan-1,4-diyl, pyridine-2,5-diyl (optionally monosubstituted by F), pyrimidine-2,5-diyl (optionally monosubstituted by F), thiophene-2,5-diyl, 1,3,4-thiazole-2,5-diyl or naphthalene-2,6-diyl (optionally mono- or di-substituted by F); M<1> and M<2> = -OC(O)-, -OCH2-, -CH2CH2-, -OC(O)-CH 2CH2-, -OCH2CH2CH2-, -C equivalent to C-, -(CH2)4- or a bond; and a and b = 0 or 1 An Independent claim is also included for switching device or display based on such liquid crystal mixtures.

Description

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

Clark and Lagerwall have shown that the use of ferroelectric liquid crystals stable (FLC) in very thin cells to optoelectric switching or display elements ment leads, which compared to the conventional TN ("twisted nematic") - Cells have up to a factor of 1000 shorter switching times (see e.g. EP-A 0 032 362). Because of these and other beneficial properties, e.g. B. the bista cheap switching option and the almost independent viewing angle contrast FLCs are generally well suited for application areas such as computer displays.

For a more in-depth discussion of the technical requirements for FLCs, go to European patent application 97118671.3 and DE-A 197 48 432 ver grasslands.

Alkylthio compounds are for use in liquid crystal mixtures already described, e.g. B. in EP-B 0 295 370; Thioester z. B. in J. Prakt. Chem. 321: 619 (1979), ibid. 320,191 (1978) Mol. Cryst. Liq. Cryst. 76, 43 (1981), DE-A-29 05 992, DE-A-30 06 982 or EP-A-0 739 884.

But since the development, especially of ferroelectric liquid crystal are not yet considered complete the manufacturers of displays on the most diverse components for Mi is interested in, among other things, because only the interaction  of the liquid crystalline mixtures with the individual components of the display device or the cells (e.g. the orientation layer) conclusions on the Quality also allows the liquid crystalline mixtures.

It has now been found that sulfur-containing compounds of the following Formula (I) has the properties of liquid crystals even in small amounts favorably influence stall mixtures, especially chiral-smectic mixtures, e.g. B. in terms of dielectric anisotropy and / or melting point tes, but also with regard to the switching behavior, the values of the tilt angle or its temperature dependence.

The invention therefore relates to sulfur-containing compounds of the formula (I)

R ¹ -X- (A ¹ -M ¹ ) _a - (A ² -M ² ) _b -A ³ -YTZR ² (I)

where the symbols and indices have the following meanings:
T non-directional
Thiophene-2,5-diyl, optionally monosubstituted by F, thiophene-2,4-diyl, optionally monosubstituted by F, cyclohexane-1,4-diyl, optionally monosubstituted by CH ₃ , CN or F, cyclohex-1 - en-1,4-diyl, cyclohex-2-en-1,4-diyl, 1-alkyl-1-silacyclohexane-1,4-diyl, cyclopentane-1,3-diyl, furan-2,5-diyl , Furan-2,4-diyl, thiazole-2,5-diyl, thiazole-2,4-diyl, 1,3-dioxane-2,5-diyl, optionally monosubstituted by CN or F
R ^{1 is} hydrogen or a straight-chain or branched (with or without asymmetrical C atoms) C _1-20 alkyl or C _2-20 alkenyl radical, where

• a) one or two non-terminal CH ₂ groups can be replaced independently of one another by -O- or -C (= O) - with the measure that two adjacent CH ₂ groups cannot be replaced in the same way and / or
• b) a CH ₂ group can be replaced by -C∼C- and / or
• c) a CH ₂ group by -Si (CH ₃ ) ₂ -, cyclopropane-1,2-diyl, cyclobutane-1,3-diyl, cyclopentane-1,4-diyl, bicyclo [1.1.1] pentane 1,3-diyl or cyclohexane-1,4-diyl can be replaced and / or
• d) one or more H atoms can be replaced by F and / or CN nen;
• e) in the case of an alkyl radical or alkenyl radical with asymmetrical carbon atoms, the asymmetrical carbon atoms -CH ₃ , -OCH ₃ , -CF ₃ , F, CN and / or Cl have substituents or in a 3- to 7-membered ring are installed, in which one or two non-adjacent CH ₂ groups can be replaced by -O- and a non-adjacent CH ₂ group by -OC (= O) -;

R ²

Hydrogen or a straight-chain or branched (with or without asymmetrical carbon atoms) C _1-20

-Alkylrest or C _2-20

Alkenyl radical, a non-terminal CH ₂

Group can be replaced by -O- or -OC (= O) - or -C (= O) O- and / or one or more H atoms can be replaced by F with the provisos that

• a) the -CH ₂ group linked to Z cannot then be replaced by -O- if Z is -O-
• b) R ² can only be hydrogen if Z is a single bond and R ^{1 is} not hydrogen

X: a single bond, -O-, OC (= O) -, -C (= O) O- or -OC (= O) O-
Y: -SC (= O) - or -SCH ₂

-
Z: a single bond or -O-
A ¹

, A ²

, A ³

are undirected independently of one another 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, where one or two H atoms independently of one another by CN, CH ₃

or F can be replaced, 1-cyclohexene-1,4-diyl, where an H atom can be replaced by F, 1-alkyl-1-silacyclohexane-1,4-diyl, pyridine-2,5-diyl, if appropriate monosubstituted by F, pyrimidine-2,5-diyl, optionally monosubstituted by F, thiophen-2,5-diyl, (1,3,4) -thiadiazole-2,5-diyl, naphthalene-2,6 -diyl, optionally substituted once or twice by F
M ¹

, M ²

are undirected independent of each other
-OC (= O) -, -OCH ₂

-, -CH ₂

CH ₂

-, -OC (= O) CH ₂

CH ₂

-,
-OCH ₂

CH ₂

CH ₂

-, -C∼C-, -CH ₂

CH ₂

CH ₂

CH ₂

- or a simple binding;
a, b are independently 0 or 1,
except the connections in which
T cyclohexane-1,4-diyl
Y -SC (= O) -
A ³

Phenylene-1,4-diyl,
X -O- or single bond
R ¹

, R ²

a C _1-10

-Alkyl group
mean.
"Terminal" means e.g. B. in R ¹

the CH ₂ linked to X or H

-Groups.
"Non-directional" means the possibility of mirror-inverted installation of the group.

Preferred compounds correspond to the formulas (Ia) to (Ic) below, in which a and b each represent 0 or 1, but in total 1 and M ¹ and M ² each represent a single bond and the remaining symbols have the above meaning

The following compounds of the formulas (I-1) to (I- 24) are particularly preferred:

in which mean:
R ^{3 is} hydrogen or a straight-chain or branched alkyl radical (with or without asymmetrical carbon atoms) with 1 to 16 carbon atoms, in which a non-terminal CH ₂ group can also be replaced by -O- or non-directed -OC (= O) - can and in which one or more H atoms can be replaced by F;
R ^{4 is} hydrogen or a straight-chain or branched alkyl radical (with or without asymmetrical carbon atoms) with 1 to 16 carbon atoms.
F _x in the case of x = 0 no substitution, in the case of x = 1 or 2 a substitution of the biphenyl by one or two (neighboring) F atoms.

The compounds of the formulas (I), in particular (I-1) to (I-24), in which R ³ and R ⁴ independently of one another are a straight-chain alkyl radical having 2 to 16 carbon atoms, are particularly preferred.

Also particularly preferred are the compounds of the formula (I), in particular re (I-1) to (I-24), in which R ^{3 is} a straight-chain alkyloxy radical having 2 to 12 C atoms and R ^{4 is} hydrogen or a straight-chain alkyl radical having 2 mean up to 12 carbon atoms.

Among the compounds of the formula (I) which are to be used as optically active components (Do tierstoft) in liquid crystal mixtures, preference is given to those in which the alkyl group contains the asymmetric C atoms in the form of at least one of the groupings

• a) -C * H (CH ₃ ) C _m H _{2m + 1} , where m has values from 2 to 8
• b) -OC * H (CH ₃ ) C _m H _{2m + 1} , where m has values from 2 to 8
• c) -OC * H (CH ₃ ) CO ₂ C _m H _{2m + 1} , where m has values from 1 to 10
• d) -OC (= O) C * H (CH ₃ ) OC _m H _{2m + 1} , where m has values from 1 to 10
• e) -OC (= O) C * H (F) C _m H _{2m + 1} , where m has values from 1 to 10
• f) -OCH ₂ C * H (F) C _m H _{2m + 1} , where m has values from 1 to 10
• g) -OCH ₂ C * H (F) C * H (F) C _m H _{2m + 1} , where m has values from 1 to 10
• h) oxirane-2,3-diyl

where C * marks the asymmetric carbon atom.

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

However, it may prove necessary to vary / 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, particular reference is made to the synthesis scheme below referred, in which the synthesis of the sulfur-containing Ver bindings is explained in more detail by way of example.  

Scheme 1

• 1. i: analogous to DE-A 34 34 335 or EP-A D 739 884:
  • 1. (H ₃ C) ₂ NC (= S) Cl, KOH, H ₂ O, tetrahydrofuran
  • 2. thermally induced rearrangement
  • 3. KOH, H ₂ O, ethylene glycol // HCl.
• 2. ii: HO ₂ CTZR ² , dicyclohexylcarbodiimide, dichloromethane or Cl-C (= O) -TZR ² , base, tetrahydrofuran
• 3. iii: Hal-CH ₂ -TZR ² , K ₂ CO ₃ , acetone

The mesogenic phenols 1 required for the synthesis according to Scheme 1 are prepared by standard methods or obtained commercially; the same applies to the carboxylic acids HO ₂ CTZR ² , while the compounds Hal-CH ₂ -TZR ² are accessible from the carboxylic acids, such as. B. described in Example 3. However, the mesogenic thiols 2 can also be obtained in other ways, e.g. B. from appropriately substituted anilines by diazotization and reaction with potassium xanthate analog Jilek et al., Coll. Czech. Chem. Commun. 55, 1266 (1990),
e.g. B. by reacting corresponding aryl halides with SH ^- analogous to Peach, in Patai, "The Chemistry of the Thiol Group", pt. 2, pages 735-744, J. Wiley & Sons, New York, 1974,
e.g. B. by implementation of appropriate aryllithium or arylmagnesium compounds with sulfur compounds analogous to March, Advanced Organic Chemistry, 2 ^nd ed., Pages 559-560, McGraw-Hill Kogakusha Ltd., Tokyo, 1977,
e.g. B. by reduction of corresponding sulfochlorides analogous to Wandell, in Patai, "The Chemistry of the Thiol Group", pt. 2, pages 216-220, J. Wiley & Sons, New York, 1974.

As for linking functional derivatives of sulfur-containing compounds with other liquid crystal-specific building blocks, is expressly referred to DE-A 197 48 432, in which a listing more familiar to the expert Methods is specified.

The invention also relates to the use of compounds of For mel (I) in liquid crystal mixtures, preferably smectic and nematic, chiral-smectic liquid crystal mixtures are particularly preferred. In particular preferred is the use in ferroelectric liquid crystal mixtures which operated in inverse mode or in displays with active matrix elements. The use in mixtures for active matrix is very particularly preferred. LCDs in which the chiral smectic liquid crystal layer has a monostable forms switching monodomain.

The invention further relates to liquid crystal mixtures, preferably two se smectic and nematic, particularly preferably chiral smectic liquid crystals Stall mixtures containing one or more compounds of the 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 wt .-%, particularly preferably 0.1 to 30 wt .-%, based on the ge whole mixture, one or more, preferably 1 to 10, particularly be preferably 1 to 5, very particularly preferably 1 to 3, of the ver according to the invention compounds of formula (I).

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 in particular in the international patent application WO 97/04039 and DE-A 197 48 432 listed, 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 containing a liquid crystal mixture, preferably a chiral smectic, containing one or more compounds of formula (I).

Switching and / or display devices that are active are particularly preferred Contain matrix elements (see e.g. DE-A 198 22 830) and a chiral smectic liquid crystal mixture.

Various documents are cited in the present application, for example wise to illustrate the technical environment of the invention. On all of these Thurs documents are hereby expressly referred to; by quotation they are considered Part of the present application.

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

example 1 5-propyl-thiophene-2-carboxylic acid- [4- (5-undecyl-pyrimidin-2-yl) phenyl] - thioester

5.1 g of 4- (5-undecyl-pyrimidin-2-yl) thiophenol (prepared analogously to DE 34 34 335), 2.6 g 5-propyl-thiophene-2-carboxylic acid (produced according to EP-B-0 364 923) and 3.1 g of dicyclohexylcarbodiimide in 50 ml of dichloromethane for 24 hours Room temperature stirred. After filtration, distillation of the dichloromethane, chromatographic purification (silica gel; dichloromethane / heptane) and umkri Installation from acetonitrile becomes the target compound in the form of colorless crystals receive.

Example 2 trans-4-pentylcyclohexane carboxylic acid- [4- (5-undecyl-pyrimidin-2-yl) phenyl] - thioester

To a solution of 5.1 g of 4- (5-undecyl-pyrimidin-2-yl) thiophenol (prepared analogous to DE 34 34 335) and 1.7 g of triethylamine in 30 ml of tetrahydrofuran at 0 ° C 3.3 g trans-4-pentylcyclohexane carboxylic acid chloride (using thionyl chloride rid made from the commercially available trans-4- Pentylcyclohexane carboxylic acid), dissolved in 20 ml of tetrahydrofuran, added dropwise. After 5 h at room temperature, triethylammonium chloride is filtered off and the filtrate brought to dryness in a vacuum. After chromatographic purification (pebble gel; Dichloromethane / heptane) and recrystallization from acetonitrile becomes the goal compound obtained in the form of colorless crystals.

Analogously, the connections (I-1) to (I-24) or the connection classes (Ia), (Ib) and (Ic) can be obtained.  

Example 3 5-propyl-thiophene-2-carboxylic acid- [4- {5- (4-decylphenyl) pyrimidine-2- yl} phenyl] thioester

is analogous to Example 1 from 4- [5- (4-decylphenyl) pyrimidin-2-yl] thiophenol [185346-51-4] and 5-propyl-thiophene-2-carboxylic acid were obtained.

Example 4 (5-propyl-thiophene-2-yl) methyl- [4- (5-undecyl-pyrimidin-2-yl) phenyl] thio ether

A mixture of equimolar amounts of 4- (5-undecyl-pyrimidin-2-yl) thiophenol, 2-bromomethyl-5-propyl-thiophene (prepared by LiAlH ₄ reduction of 5-propyl-thiophene-2-carboxylic acid methyl ester and subsequent reaction with triphenylphosphine / Bromine) and triple molar amounts of potassium carbonate is refluxed in acetone. After the end of the reaction, the mixture is filtered and the filtrate is brought to dryness in vacuo. After chromatographic purification (silica gel, dichloromethane) and recrystallization, the target compound can be obtained.

All compounds of the formula (I) in which Y has the meaning -SCH ₂ - can be obtained analogously.

Claims (12)

1. sulfur-containing compounds of the formula (I),
R ¹ -X- (A ¹ -M ¹ ) _a - (A ² -M ² ) _b -A ³ -YTZR ² (I)
where the symbols and indices have the following meanings:
T non-directional
Thiophene-2,5-diyl, optionally monosubstituted by F, thiophene-2,4-diyl, optionally monosubstituted by F, cyclohexane-1,4-diyl, optionally monosubstituted by CH ₃ , CN or F, cyclohex-1 - en-1,4-diyl, cyclohex-2-en-1,4-diyl, 1-alkyl-1-silacyclohexane-1,4-diyl, cyclopentane-1,3-diyl, furan-2,5-diyl , Furan-2,4-diyl, thiazole-2,5-diyl, thiazole-2,4-diyl, 1,3-dioxane-2,5-diyl, optionally monosubstituted by CN or F
R ^{1 is} hydrogen or a straight-chain or branched (with or without asymmetrical C atoms) C _1-20 alkyl or C _2-20 alkenyl radical, where

• a) one or two non-terminal CH ₂ groups can be replaced independently of one another by -O- or -C (= O) - with the proviso that two adjacent CH ₂ groups cannot be of the same type and / or
• b) a CH ₂ group can be replaced by -C∼C- and / or
• c) a CH ₂ group by -Si (CH ₃ ) ₂ -, cyclopropane-1,2-diyl, cyclobutane-1,3-diyl, cyclopentane-1,4-diyl, bicyclo [1.1.1] pentane 1,3-diyl or cyclohexane-1,4-diyl can be replaced and / or
• d) one or more H atoms can be replaced by F and / or CN;
• e) in the case of an alkyl radical or alkenyl radical with asymmetrical carbon atoms, the asymmetrical carbon atoms -CH ₃ , -OCH ₃ , -CF ₃ , F, CN and / or Cl have substituents or in a 3- to 7-membered ring are installed, in which one or two non-adjacent CH ₂ groups can be replaced by -O- and a non-adjacent CH ₂ group by -OC (= O) -;

R ^{2 is} hydrogen or a straight-chain or branched (with or without asymmetrical carbon atoms) C _1-20 -alkyl radical or C _2-20 -alkenyl radical, where a non-terminal CH ₂ group by -O- or -OC (= O) - or -C (= O) O- can be replaced and / or one or more H atoms can be replaced by F with the provisos that

• a) the -CH ₂ group linked to Z cannot then be replaced by -O- if Z is -O-
• b) R ² can only be hydrogen if Z is a single bond and R ^{1 is} not hydrogen

X: a single bond, -O-, OC (= O) -, -C (= O) O- or -OC (= O) O-
Y: -SC (= O) - or -SCH ₂ -
Z: a single bond or -O-
A ¹ , A ² , A ³ are undirected independently of one another 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, where one or two H atoms can be replaced independently of one another by CN, CH ₃ or F, 1-cyclohexene-1,4-diyl, where one H atom can be replaced by F, 1 -Alkyl-1-silacyclohexane-1,4-diyl, pyridine-2,5-diyl, optionally monosubstituted by F, pyrimidine-2,5-diyl, optionally monosubstituted by F, thiophene-2,5-diyl , (1,3,4) -Thiadiazol-2,5-diyl, naphthalene-2,6-diyl, optionally mono- or disubstituted by F
M ¹ , M ² are undirected independently of one another
-OC (= O) -, -OCH ₂ -, -CH ₂ CH ₂ -, -OC (= O) CH ₂ CH ₂ -,
-OCH ₂ CH ₂ CH ₂ -, -C∼C-, -CH ₂ CH ₂ CH ₂ CH ₂ - or a single bond;
a, b are independently 0 or 1. except the connections in which
T cyclohexane-1,4-diyl
Y -SC (= O) -
A ³ phenylene-1,4-diyl,
X -O- or single bond
R ¹ , R ^{2 is} a C _1-10 alkyl group
mean. 2. Sulfur-containing compounds according to claim 1 of the formula (Ia)
in which mean:
a and b each 0 or 1, but in total 1
M ¹ and M ² each have a single bond
and the remaining radicals are as defined in claim 1. 3. Sulfur-containing compounds according to claim 1 of the formula (Ib)
in which mean:
a and b each 0 or 1, but in total 1
M ¹ and M ² each have a single bond
and the remaining radicals are as defined in claim 1. 4. Sulfur-containing compounds according to claim 1 of the formula (Ic)
in which mean:
a and b each 0 or 1, but in total 1
M ¹ and M ² each have a single bond
and the remaining radicals are defined as in claim 1. 5. Liquid crystal mixture containing at least one compound of For mel (I) according to one of claims 1 to 4. 6. Liquid crystal mixture according to claim 5, characterized in that it chiral is smectic.   7. Liquid crystal mixture according to claim 5, characterized in that it is nematic. 8. Liquid crystal mixture according to one of claims 5 to 7, characterized ge indicates that it contains 0.01 to 80% by weight of one or more compounds of formula (I) contains. 9. Switching and / or display device containing a liquid crystal Schung according to any one of claims 5 to 8. 10. Switching and / or display device according to claim 9, containing one Chiral smectic liquid crystal mixture, characterized in that it contains Ak tivmatrix elements and the liquid crystal layer switch a monostable de forms mono-domain.