DE4026223A1 - Novel 5-oxy-2-phenyl-pyridine(s) - useful as component in ferroelectric liq. crystal media to give favourable viscosity, high spontaneous polarisation etc. - Google Patents

Abstract

Novel 5-oxy-2-phenylpyridines of formula (I) are claimed as are also, (i) multi-component ferroelectric liq. crystal media contg. one or more cpds. (I) and (ii) electro-optical displays contg. a medium of type (i) as dielectric. m and n = 1-18, Q1 = a bond, -O-, trans-1,4-cyclohexylene or 1,4-phenylene, and Q2 = a bond, -CO-, or a gp. of formula (II) or (III) with the proviso that (a) when Q1=Q2= a bond, the sum m + n is 11 or more, and (b) when Q2 = -CO-, the CnH2n+1 residue is straight-chained. USE/ADVANTAGE - (I) are suitable for use in chiral, tilted smectic media in which give the advantages of chemical stability, favourable ferroelectric phase ranges, favourable viscosity, broad S

Description

The invention relates to 5-oxy-2-phenylpyridine of the formula I.

wherein
m and n are each independently 1 to 18,
Q¹ is -O-, trans-1,4-cyclohexylene, 1,4-phenylene or a single bond and

or a single bond means
with the proviso that a) in the case of Q¹ = Q² = single bond is the sum of m + n ≧ 11, and b) in the case Q² = CO the radical C _n H _{2n + 1 is} straight-chain, and these containing ferroelectric liquid-crystalline media.

Chiral tilted smectic liquid-crystalline media with ferroelectric properties can be produced Become one by using basic mixes several tilted smectic phases with a suitable chiral dopant (L. A. Beresnev et al., Mol. Cryst. Liq. Cryst., 89, 327 [1982]; H.R. Brand et al., J. Physique, 44 [Lett.], L 771 [1983]). Such  Media can be used as dielectrics for fast switching Displays are used on the one of Clark and Lagerwall described principle of SSFLC technology (N.A. Clark and S.T. Lagerwall, Appl. Phys. Lett., 36, 899 [1980]; USP 43 67 924) based on the ferroelectric Properties of the chiral tilted medium based. In these media are the elongated ones Molecules are arranged in layers, with the molecules have a tilt angle to the layer normal. At the Progression from layer to layer changes Tilt direction at a small angle with respect to a perpendicular to the layers standing axis, so that a Helix structure is formed. In displays that are on the Principle of SSFLC technology are smectic Layers perpendicular to the plates of the cell arranged. The helical arrangement of the Tiltrichtungen The molecules are separated by a very small distance Plates (about 1-2 μm) suppressed. This will be the Longitudinal axes of molecules forced to move in a plane parallel to the plates of the cell, thereby Two excellent tilt orientations arise. By Applying a suitable alternating electric field may have a spontaneous polarization in the liquid crystalline phase between these two states be switched back and forth. This switching process is much faster than conventional twisted cells (TN-LCD's) that are based on nematic Liquid crystals are based.

A major disadvantage for many applications of currently available materials with chiral tilted smectic phases (such as Sc *, but also S _H *, S _i *, S _J *, S _K *, S _G *, S _F *) is their low chemical, thermal and photo-stability. Another disadvantageous feature of displays based on currently available chiral tilted smectic media is that the spontaneous polarization is too small to adversely affect the switching performance of the displays and / or the pitch and / or tilt and / or viscosity of the media does not meet the requirements of display technology. In addition, the temperature range of the ferroelectric media is usually too small and is predominantly at too high temperatures.

It has now been found that the use of compounds of formula I as components of chiral tilted smectic media the mentioned disadvantages substantially can diminish. The compounds of the formula I are thus chiral tilted smectic components liquid-crystalline media excellently suitable. In particular are chemically very stable with their help chiral tilted smectic liquid crystalline media with favorable ferroelectric phase ranges, favorable Values for the viscosity, especially with broad Sc * phase areas, excellent supercoolability up to to temperatures below 0 ° C, without crystallization occurs and for such phases high values for the spontaneous polarization can be produced. P is the spontaneous Polarization in nC / cm². The compounds of the formula I However, they are also suitable for liquid-crystalline media for the electro-clinker effect.

The compounds of the formula I have a broad Scope of application. Depending on the selection of the Substituents may use these compounds as base materials serve, from which liquid-crystalline smectische Media composed for the most part are; but it can also be compounds of formula I Liquid-crystalline base materials from other classes of compounds be added, for example the dielectric and / or optical anisotropy and / or  the viscosity and / or the spontaneous polarization and / or the phase range and / or the tilt angle and / or or to vary the pitch of such a medium.

In GB 21 61 808 is a very broad general formula for nematic phenylpyridines for use in multiplexed Cells, some of which claimed here Compounds of the formula I comprises. In GB 21 61 808 are but no evidence for Sc phases in compounds of this type, but rather the compounds described therein be nematic and have an excellent miscibility having other nematic liquid crystals. Specifically, the following compounds are indicated:

2- (p-pentylphenyl) -5-butyloxypyridine, C → I 38 ° C, I → S 34 ° C,
2- (p-butylphenyl) -5-ethoxypyridine, C → I 29.5 ° C,
2- (p-pentylphenyl) -5-propyloxypyridine, C → I 42 ° C,
2- (p-Hexylphenyl) -5-butyloxypyridine, C → S 26 ° C, S → I 44.5 ° C.

From the viewpoint of good miscibility with other nematic liquid crystals, the unidentified smectic phases described in two of these compounds can not be S _c but, for example, S _B.

From JP 63-1 65 344 are optically active phenylpyridines the formula

known.

However, these are not suitable as achiral base materials for ferroelectric liquid-crystalline media, but are used as dopants.  

The expert could not therefore from the prior art recognize that the compounds of the invention predominantly have broad and favorable Sc phases as well as favorable values for the rotational viscosity distinguished. The invention thus provides the 5-oxy-2-phenylpyridines of the formula I.

The invention further ferroelectric Liquid-crystalline media containing at least a compound of formula I and liquid crystal displays, in particular ferroelectric electro-optical Ads containing such media.

The media according to the invention preferably contain at least two, in particular at least three compounds of formula I. Particularly preferred are inventive chiral tilted smectic liquid crystalline Phases whose achiral base mixture in addition to compounds of the formula I at least one other component with negative or absolute smaller positive contains dielectric anisotropy. These others Component (s) of the achiral base mixture can be 1 to 50%, preferably 10 to 25%, make the base mixture. As further components with amount smaller positive or negative dielectric anisotropy are compounds of formula IV, which are the Compounds of sub-formulas IVa to IVi include:

R⁴ and R⁵ are each preferably straight-chain alkyl, Alkoxy, alkanoyloxy or alkoxycarbonyl with, respectively 3 to 12 carbon atoms. X is preferably O. In the compounds of Formulas IVa, IVb, IVd, IVe, IVf and IVg also a 1,4-phenylene group laterally by halogen or CN, especially preferably substituted by fluorine his.

Particularly preferred are the compounds of the sub-formulas IVa, IVb, IVd and IVf, wherein R⁴ and R⁵ respectively straight-chain alkyl or alkoxy each having 5 to 10 C atoms means.

Particularly preferred single compounds are as follows Table I given:

Table I

The compounds of the sub-formulas IVc, IVh and IVi are suitable as additives to melting point depression and Normally, the base mixes will not work anymore as 5%, preferably 1 to 3% added. R⁴ and R⁵ mean in the compounds of sub-formulas IVc, IVh and IVi preferably straight-chain alkyl with 2 to 7, preferably 3 to 5, carbon atoms. Another to lower the melting point in the phases according to the invention suitable class of compounds is that of the formula

where R⁴ and R⁵ are those given for IVc, IVh and IVi have preferred meaning.

As other components with negative dielectric Anisotropy are also compounds containing the structural element A, B or C.

Preferred compounds of this type correspond to the formulas Va, Vb and Vc:

R 'and R' 'are each preferably straight-chain Alkyl or alkoxy groups each having 2 to 10 carbon atoms. Q 1 and Q 2 are each 1,4-phenylene, trans-1,4- Cyclohexylene, 4,4'-biphenylyl, 4- (trans-4-cyclohexyl) - phenyl, trans, trans-4,4'-bicyclohexyl or one of Groups Q¹ and Q² also a single bond.

Q³ and Q⁴ are each 1,4-phenylene, 4,4'-biphenylyl or trans-1,4-cyclohexylene. One of the groups Q³ and Q⁴ may also be 1,4-phenylene wherein at least a CH group is replaced by N. R '' 'is an optical one active residue with an asymmetric carbon atom the structure

Particularly preferred compounds of formula Vc are those of formula Vc ':

wherein A is 1,4-phenylene or trans-1,4-cyclohexylene and n is 0 or 1 means.  

The compounds of formula I include those below cited preferred binuclear and trinuclear Materials:

wherein m is preferably 7 to 12 and n is 6 to 12

wherein n and m are preferably each independently 5 to 12 mean

wherein the radical C _n H _{2n + 1 is} straight-chain, and preferably Q ₁ is -O- or a single bond and m and n are each independently 5 to 12

wherein preferably Q¹ is -O- or a single bond, m is 5 to 12 and n is 2 to 12

wherein preferably Q is -O- or a single bond, m is 5 to 12 and n is 2 to 12

wherein m is preferably 1 to 12 and n is 1 to 12

wherein m is preferably 3 to 12 and n is 2 to 12.

These include those of sub-formulas Ia and Ib, in particular IB, particularly preferred.

m is preferably 5 to 14, in particular 6 to 12, n is preferably 3 to 12. The radicals C _m H _{2m + 1} and C _n H _{2n + 1} are preferably straight-chain. Compounds of the formula I having relatively short such radicals are also suitable as components of nematic media (n and m independently of one another 1 to 7).

Q¹ is preferably -O-.

The compounds of the formula I are known per se Methods, as in the literature (eg in the well-known Standard works such as Houben-Weyl, Methods of Organic Chemistry, Georg Thieme Verlag, Stuttgart).

If desired, the starting materials can also be formed in situ be such that you get them out of the reaction mixture not isolated but immediately further to the compounds of Formula I implements.

The compounds of the invention can be according to the following Produce reaction scheme simply:

Scheme 1

Scheme 2

Scheme 3

The compounds of the invention are further characterized by Coupling of organometallic zinc compounds with corresponding bromopyridine derivatives accordingly DE-OS 36 32 410 available.

In the following, the synthesis of some becomes particularly interesting Hydroxy intermediates described:

• a) 5-hydroxy-2 (4-alkylphenyl) pyridines or 5-hydroxy-2 (4-alkoxyphenyl) pyridines are obtainable from 2-Benzyloxytrimethiniumsalz by condensation with 4-alkyl or 4-alkoxyacetophenones, reaction with NH₃ / NH₄Cl or ammonium acetate.
  Analogous to the instructions of Ch. Jutz et al. (Liebigs Ann. Chem., 1975, 874-900) and subsequent hydrogenolysis or from 4-alkyl- or 4-alkoxyphenylboronic acid by coupling with 5-acetoxy-2-bromopyridine (obtainable from 5-hydroxy-2-bromopyridine by esterification) in the presence of a Pd catalyst according to the work of Suzuki et al. (Synth.Commun., 11, 513-19 [1981]).
• b) 5-alkoxy-2 (4-hydroxyphenyl) pyridines are available by coupling of 4-benzyloxyphenylboronic acid with 5-alkoxy-2-bromopyridine corresponding to the above Literature and subsequent hydrogenolysis.

The liquid-crystalline media according to the invention contain preferably in addition to one or more inventive Compounds as further constituents 2 to 40, in particular 4 to 30 components. Very particularly preferably included these media in addition to one or more inventive Compounds 7 to 25 components. These others Ingredients are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, especially substances from the classes of Azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, Phenyl or cyclohexyl benzoates, cyclohexane-carboxylic acid phenyl or cyclohexyl esters, phenyl or cyclohexyl esters cyclohexylbenzoic acid, phenyl or cyclohexyl esters cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl ester benzoic acid, cyclohexanecarboxylic acid or cyclohexylcyclohexanecarboxylic acid, phenylcyclohexanes, Cyclohexylbiphenyls, phenylcyclohexylcyclohexanes, Cyclohexylcyclohexanes, cyclohexylcyclohexenes, cyclohexylcyclohexylcyclohexenes, 1,4-bis-cyclohexylbenzenes, 4,4'- Bis-cyclohexylbiphenyls, phenyl or cyclohexylpyrimidines, Phenyl- or cyclohexylpyridines, phenyl- or cyclohexyl-dioxanes, Phenyl or cyclohexyl-1,3-dithiane, 1,2-diphenylethane, 1,2-dicyclohexylethane, 1-phenyl-2-cyclohexylethane, 1-cyclohexyl-2- (4-phenyl-cyclohexyl) ethanes, 1-cyclohexyl-2-biphenylylethanes, 1-phenyl-2-cyclohexylphenylethanes, optionally halogenated stilbenes, Benzylphenyl ethers, tolans and substituted cinnamic acids. The 1,4-phenylene groups in these compounds can also be fluorinated.  

The most important as further constituents according to the invention Media in question compounds can be through Formulas 1, 2, 3, 4 and 5 characterize:

R'-L-E-R '' 1 R'-L-COO-E-R '' 2 R'-L-OOC-E-R '' 3 R'-L-CH₂CH₂-E-R '' 4 R'-L-C≡C-E-R '' 5

In the formulas 1, 2, 3, 4 and 5, L and E, denote may be the same or different, each independently from each other a bivalent radical from the -Phe-, -Cyc, -Phe-Phe, -Phe-Cyc, -Cyc-Cyc, -Pyr-, -Dio, G-Phe and -G-Cyc and their mirror images formed Group, wherein Phe is unsubstituted or by Fluorine-substituted 1,4-phenylene, Cyc trans-1,4-cyclohexylene or 1,4-cyclohexenylene, Pyr pyrimidine-2,5-diyl or pyridine-2,5-diyl, dio-1,3-dioxane-2,5-diyl and G 2- (trans-1,4-cyclohexyl) -ethyl, pyrimidine-2,5-diyl, Pyridine-2,5-diyl or 1,3-dioxane-2,5-diyl.

Preferably one of the radicals L and E is cyc, phe or Pyr. E is preferably Cyc, Phe or Phe-Cyc. Preferably contain the media of the invention one or several components selected from the compounds of Formulas 1, 2, 3, 4 and 5, wherein L and E are selected from the group Cyc, Phe and Pyr and at the same time one or more components selected from the compounds of the formulas 1, 2, 3, 4 and 5, wherein one of the radicals L and E is selected from the group Cyc, Phe and Pyr and the other radical is selected from the group -Phe-Phe-, -Phe-Cyc, -Cyc-Cyc, -G-Phe and -G-Cyc-, and optionally one or more components selected from the Compounds of the formulas 1, 2, 3, 4 and 5, wherein the  Radicals L and E are selected from the group -Phe-Cyc-, -Cyc-Cyc, -G-Phe and -G-Cyc.

R 'and R' 'in the compounds of the sub-formulas 1a, 2a, 3a, 4a and 5a independently of one another Alkyl, alkenyl, alkoxy, alkenyloxy or alkanoyloxy with up to 8 carbon atoms. For most of these compounds R 'and R' 'are different from each other, where one of these radicals is usually alkyl or alkenyl. In the Compounds of sub-formulas Ib, 2b, 3b, 4b and 5b means R "-CN, -CF₃, F, Cl or -NCS; R has the case at the compounds of the sub-formulas 1a to 5a specified Meaning and is preferably alkyl or alkenyl. But also other variants of the proposed substituents in The compounds of the formulas 1, 2, 3, 4 and 5 are customary. Many such substances or mixtures of which are commercially available. All these substances are by literature methods or in analogy available.

The media according to the invention preferably contain in addition Components from the group of compounds 1a, 2a, 3a, 4a and 5a (group 1) also components from the group of Compounds 1b, 2b, 3b, 4b and 5b (group 2), their proportions preferably as follows:

Group 1: 20 to 90%, in particular 30 to 90%,
Group 2: 10 to 80%, in particular 10 to 50%,

wherein the sum of the proportions of the compounds of the invention and the compounds from groups 1 and 2 to 100% yield.  

The media according to the invention preferably contain 1 to 40%, in particular preferably 5 to 30% of inventive Links. Further preferred Media containing more than 40%, in particular 45 to 90% of compounds of the invention. The media included preferably three, four or five according to the invention Links.

The preparation of the media according to the invention takes place in in the usual way. In general, the components are dissolved in each other, useful at elevated temperature. By suitable additives, the liquid-crystalline Phases modified according to the invention that in all hitherto known species of Liquid crystal display elements can be used. Such additives are known in the art and in the Literature described in detail (H. Kelker / R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980). For example, pleochroic dyes for the production of colored guest host systems or substances for changing the dielectric anisotropy, the viscosity and / or the orientation of the nematic Phases are added.

The following examples are intended to illustrate the invention, without limiting it. mp. = Melting point, cp. = Clearing point. Above and below, percentages are by weight; All temperatures are in degrees Celsius. "Usual work-up" means: you add water, extracted with methylene chloride, separated, dried organic phase, evaporated and purified by the product Crystallization and / or chromatography.  

It also means:
K: crystalline solid state, S: smectic phase (the index indicates the phase type), N: nematic state, Ch: cholesteric phase, I: isotropic phase. The number between two symbols indicates the transformation temperature in degrees Celsius.

Example 1

0.1 mol of 2- (4-nonylphenyl) -5-hydroxypyridine (prepared by condensation of 4-nonylacetophenone with 2-benzyloxytrimethinium perchlorate according to Jutz et al. (please refer Page 11) followed by hydrogenolysis of the benzyl ether) are reacted with 0.11 mol of 1-bromoheptane and 0.11 mol Potassium carbonate in dimethylformamide as solvent etherified. After workup, the 2- (4-nonylphenyl) - 5-heptyloxypyridine recrystallized from isopropanol.

Analog is obtained by reacting 4-benzyloxyacetophenone with 2-octyloxytrimethinium perchlorate, ammonium acetate and hydrogenating cleavage of the benzyl ether 2- (4-hydroxyphenyl) -5-octyloxypyridine, which is treated with 1-bromodecane to 2- (4-n-decyloxyphenyl) -5-octyloxypyridine is alkylated.

Examples 2-204

The following compounds of the formula I are prepared analogously or by etherification or esterification of corresponding hydroxy compounds by standard methods:

example 205

0.1 mol of 4- (trans-4-pentylcyclohexyl) phenylboronic acid are mixed with 0.1 mol of 2,5-dibromopyridine in toluene / 2N-NaHCO₃- Solution (1: 1) with tetrakis [triphenylphosphine] palladium (0) coupled as a catalyst according to Scheme 2. The coupling product is at -100 ° C in THF with n-butyllithium and then mixed with trimethyl borate. The thus obtained Boronic acid is mixed with 20 ml of a 3% H₂O₂ solution and stirred at room temperature for 2 hrs. The obtained 2- [4- (trans-4-pentylcyclohexyl) phenyl] -5-hydroxypyridine is etherified analogously to Example 1 with 1-bromooctane. To the work-up is 2- [4- (trans-4-pentylcyclohexyl) - Reconstructed phenyl] -5-octyloxypyridine.

Example 206-223

The following compounds of the formula I are prepared analogously:

Claims (9)

1. 5-Oxy-2-phenylpyridine of the formula I. wherein
m and n are each independently 1 to 18,
Q¹ is -O-, trans-1,4-cyclohexylene, 1,4-phenylene or a single bond and or a single bond means
with the provisos that a) in the case of Q¹ = Q² = single bond, the sum of m + n ≧ 11, and b) in the case of Q² = CO, the radical -C _n H _{2n + 1 is} straight-chain. 2. 5-Oxy-2-phenylpyridines according to claim 1, characterized by the formula Ia wherein m is 7 to 12 and n is 6 to 12. 3. 5-Oxy-2-phenylpyridines according to claim 1, characterized by the formula Ib wherein n and m are each independently 5 to 12. 4. 5-Oxy-2-phenylpyridines according to claim 1, characterized by the formula Ic wherein the radical C _n H _{2n + 1 is} straight-chain, and Q ₁ is -O- or a single bond and m and n are each independently 5 to 12. 5. 5-Oxy-2-phenylpyridines according to claim 1, characterized by the formula Id wherein Q¹ is -O- or a single bond, m is 5 to 12 and n is 2 to 12. 6. 5-Oxy-2-phenylpyridines according to claim 1, characterized by the formula Ie wherein Q¹ is -O- or a single bond, m is 5 to 12 and n is 2 to 12. 7. 5-Oxy-2-phenylpyridines according to claim 1 of the formula If wherein m and n are each independently 1 to 12. 8. Ferroelectric liquid-crystalline medium with at least two liquid crystalline components, characterized in that it is one or more Compounds according to at least one of the claims 1 to 7 contains. 9. Electro-optical display, characterized in that, as a dielectric, it is a medium according to claim 8 contains.