DE102012004393A1 - Compounds for a liquid crystalline medium and their use for high frequency components - Google Patents

Abstract

The present invention relates to compounds with at least one bicyclic or tricyclic ring system connected with acetylene or difluoroethylene bridges, their use for high-frequency components, liquid-crystalline media containing the compounds and high-frequency components containing these media, especially antennas, especially for the gigahertz range. The liquid-crystalline media are used, for example, to phase-shift microwaves for tunable 'phased-array' antennas.

Description

The present invention relates to compounds having at least one bicyclic or tricyclic ring system which is connected to acetylene or difluoroethylene bridges, their use for high-frequency components, liquid-crystalline media containing the compounds and high-frequency components containing these media, in particular antennas, especially for the gigahertz range. The liquid-crystalline media are used, for example, for phase shifting microwaves for tunable 'phased-array' antennas.

Liquid-crystalline media have long been used in electro-optical displays (Liquid Crystal Displays - LCDs) to display information.

1,4-Diethynylbenzene derivatives are disclosed in the publications EP 0968988 A1 . DE 19907941 A1 . DE 10120024 A1 and JP 08012599 A proposed as liquid-crystalline components. Compounds having a (difluoro) ethylene bridge between two rings are not disclosed therein.

Recently, however, liquid-crystalline media are also proposed for use in components, or in components, for microwave technology, such. In DE 10 2004 029 429 A and in JP 2005-120208 (A) ,

A technically valuable application of the liquid-crystalline media in high-frequency technology is based on their property that they can be controlled by a variable voltage in their dielectric properties, especially for the gigahertz range. Thus, tunable antennas can be constructed that do not contain any moving parts ( A. Gaebler, A. Moessinger, F. Goelden, et al., "Liquid Crystal-Reconfigurable Antenna Concepts for Space Applications at Microwave and Millimeter Waves," International Journal of Antennas and Propagation, vol. 2009, Article ID 876989, 7 pages, 2009. doi: 10.1155 / 2009/876989 ).

The publication A. Penirschke, S. Müller, P. Scheele, C. Weil, M. Wittek, C. Hock and R. Jakoby: "Cavity Perturbation Method for Characterization of Liquid Crystals up to 35 GHz", 34th European Microwave Conference - Amsterdam, 545-548 describes, inter alia, the properties of the known single liquid crystalline substance K15 (Merck KGaA, Germany) at a frequency of 9 GHz.

1- (phenylethynyl) tolanes, also referred to below as bistolan compounds, with an alkyl substitution on the central phenylene ring are known to the person skilled in the art. For example, the publication discloses S.-T. Wu, C.-S. Hsu, K.-F. Shyu Appl. Phys. Lett. (1999), 74 (3), 344-346 various liquid crystalline bistolane compounds having a lateral methyl group of the formula

CS Hsu, KF Shyu, YY Chuang, S.-T. Wu Liq. Cryst. (2000), 27 (2), 283-287 discloses, in addition to such liquid-crystalline bistolan compounds having a lateral methyl group, also corresponding compounds having a lateral ethyl group and proposes their use, inter alia, in "liquid crystal optically phased arrays" before.

DE 10 2004 029 429 A (supra) describes the use of conventional liquid-crystal media in microwave technology, including in phase shifters. There, liquid-crystalline media are already being investigated for their properties in the corresponding frequency range.

oder abgeleitete Derivate sind beschrieben als Bestandteile von organischen Dünnschicht-Transistoren ( EP 2 073 290 A1 ), als photosensibilisierende Farbstoffe zur Steuerung eines „photoacid generating systems” ( WO 20081021208 A2 ) und als Bestandteile von Datenaufzeichnungsmedien ( JP 2004-082439 A ). Flüssigkristalline Eigenschaften und ihre Verwendung in flüssigkristallinen Medien sind bisher nicht beschrieben. In EP 2 073 290 A1 werden außerdem folgende Verbindungen benannt:

A compound of the formula

or derived derivatives are described as constituents of organic thin-film transistors ( EP 2 073 290 A1 ), as photosensitizing dyes for controlling a "photoacid generating systems "( WO 20081021208 A2 ) and as constituents of data recording media ( JP 2004-082439 A ). Liquid-crystalline properties and their use in liquid-crystalline media are not yet described. In EP 2 073 290 A1 the following compounds are also named:

In each case the four symmetrically substituted molecules are mentioned.

However, the previously known compositions or individual compounds are generally associated with disadvantages. Most of them, among other deficiencies, lead to unfavorably high losses and / or inadequate phase shifts or material quality.

For use in high-frequency technology, liquid-crystalline media with special, hitherto unusual, unusual properties or combinations of properties are needed.

Thus, new components are required for liquid crystalline media with improved properties. In particular, the loss in the microwave range must be reduced and the material quality (η) to be improved. Tunable antennas also require liquid crystalline media with fast response time to a changed voltage between the electrodes of the cell.

There is also a need to improve the low-temperature behavior of the components. Here, both an improvement of the operating characteristics, as well as the shelf life required.

There is therefore a considerable need for liquid-crystalline media with suitable properties for corresponding practical applications.

Surprisingly, it has been found that the compounds according to the invention have broad nematic phases and high clearing points (transition of the nematic phase into the isotropic phase). At the same time, the optical anisotropy (Δn) is in a favorable range for the phase shift of microwaves. Taking advantage of this effect, it has now surprisingly been found that the compounds according to the invention can be used to produce liquid-crystalline media having a suitable, nematic phase range and high Δn which do not or at least only to a significantly lesser extent have the disadvantages of the prior art materials.

• a) einen Rest der Formeln
  
  
  worin X O, S, SO, SO₂, NH, NR³ oder NO bedeutet, ein oder zwei nicht benachbarte -CH₂- durch X ersetzt sein können, und R³ wie R¹ definiert ist,
• b) 1,4-Phenylen, worin ein oder mehrere, bevorzugt ein bis zwei CH-Gruppen durch N ersetzt sein können,
• c) einen Rest der Formeln
  
• d) trans-1,4-Cyclohexylen oder Cyclohexenylen, worin auch eine oder zwei nicht benachbarte CH₂-Gruppen durch -O- und/oder -S- ersetzt sein können, und worin H durch F ersetzt sein kann, oder
• e) einen Rest aus der Gruppe 1,4-Bicyclo(2,2,2)-octylen, Cyclobutan-1,3-diyl, Spiro[3.3]heptan-2,6-diyl, Thiophen-2,5-diyl, Thiophen-2,4-diyl, Furan-2,5-diyl, Furan-2,4-diyl, und worin in den Gruppen a), b), c), d) und e) auch ein oder mehrere H-Atome gegen Br, Cl, F, CN, -NCS, -SCN, SF₅, C₁-C₁₀ Alkyl, C₁-C₁₀ Alkoxy, C₃-C₆ Cyclalkyl oder eine ein- oder mehrfach fluorierte C₁-C₁₀ Alkyl- oder Alkoxygruppe ersetzt sein können, und wobei mindestens ein Rest aus A², A³ und A⁴ einen Rest nach a) darstellt, R¹ und R² jeweils unabhängig voneinander einen halogenierten oder unsubstituierten Alkylrest mit 1 bis 15 C-Atomen, wobei in diesen Resten auch eine oder mehrere CH₂-Gruppen jeweils unabhängig voneinander durch -C≡C-, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -(CO)O-, -O(CO)-, -(CO)-, -O- oder -S- so ersetzt sein können, dass O- oder S-Atome nicht direkt miteinander verknüpft sind, F, Cl, Br, CN, CF₃, OCF₃, SCN, NCS oder SF₅, Z², Z³ unabhängig voneinander -C≡C- oder
  
  Y¹, Y² unabhängig voneinander H, F, Cl, C₁-C₁₀ Alkyl, bevorzugt H oder F, besonders bevorzugt F, Z¹, Z⁵ unabhängig voneinander, eine Einfachbindung, -C≡C-, -CH=CH-, -CH₂O-, -(CO)O-, -CF₂O-, -CF₂CF₂-, -CH₂CF₂-, -CH₂CH₂-, -(CH₂)₄-, -CH=CF- oder -CF=CF-, wobei asymmetrische Brücken nach beiden Seiten orientiert sein können, p 1 oder 2, und m, n unabhängig voneinander 0, 1 oder 2, oder R¹-(A¹-Z¹)_m-A²- oder -A⁴-(Z⁵-A⁵)_n-R² unabhängig optional auch einen Rest der Formeln
  
  bedeuten.

The invention relates to compounds of the formula I, R ¹ - (A ¹ -Z ¹ ) _m -A ² -Z ² - (A ³ ) _p -Z ³ -A ⁴ - (Z ⁵ -A ⁵ ) _n -R ² I wherein
A ^1-5 independent of each other, optionally aligned on both sides,

• a) a remainder of the formulas
  
  
  wherein X is O, S, SO, SO ₂ , NH, NR ³ or NO, one or two non-adjacent -CH ₂ - may be replaced by X, and R ³ is defined as R ¹ ,
• b) 1,4-phenylene, in which one or more, preferably one or two, CH groups may be replaced by N,
• c) a remainder of the formulas
  
• d) trans-1,4-cyclohexylene or cyclohexenylene, wherein also one or two non-adjacent CH ₂ groups may be replaced by -O- and / or -S-, and in which H may be replaced by F, or
• e) a radical from the group consisting of 1,4-bicyclo (2,2,2) octyl, cyclobutane-1,3-diyl, spiro [3.3] heptane-2,6-diyl, thiophene-2,5-diyl, Thiophene-2,4-diyl, furan-2,5-diyl, furan-2,4-diyl, and wherein in the groups a), b), c), d) and e) also one or more H atoms against Br, Cl, F, CN, -NCS, -SCN, SF ₅ , C ₁ -C ₁₀ alkyl, C ₁ -C ₁₀ alkoxy, C ₃ -C ₆ cyclalkyl or a mono- or polyfluorinated C ₁ -C ₁₀ Or at least one radical from A ² , A ³ and A ^{4 is} a radical according to a), R ¹ and R ^{2 are} each independently of one another a halogenated or unsubstituted alkyl radical having 1 to 15 C atoms, wherein in these radicals also one or more CH ₂ groups each independently of one another by -C≡C-, -CH = CH-, -CF = CF-, -CF = CH-, -CH = CF-, - (CO) O, -O (CO) -, - (CO) -, -O- or -S- can be replaced so that O or S atoms are not directly linked to each other, F, Cl, Br, CN, CF. ₃ , OCF ₃ , SCN, NCS or SF ₅ , Z ² , Z ³ independently of each other - C≡C or
  
  Y ¹ , Y ² independently of one another are H, F, Cl, C ₁ -C ₁₀ -alkyl, preferably H or F, particularly preferably F, Z ¹ , Z ⁵ independently of one another, a single bond, -C≡C-, -CH = CH -, CH ₂ O-, - (CO) O-, -CF ₂ O-, -CF ₂ CF ₂ -, -CH ₂ CF ₂ -, -CH ₂ CH ₂ -, - (CH ₂ ) ₄ -, -CH = CF- or -CF = CF-, where asymmetric bridges may be oriented to both sides, p 1 or 2, and m, n independently of one another 0, 1 or 2, or R ¹ - (A ¹ -Z ¹ ) _m -A ² - or -A ⁴ - (Z ⁵ -A ⁵ ) _n -R ² independently optionally also a radical of the formulas
  
  mean.

worin R¹ und R² beide CH₃, beide F oder beide CF₃ bedeuten, nicht umfasst sind.Preferred compounds of the formula I are those in which the compounds of the formulas

wherein R ¹ and R ^{2 are} both CH ₃ , both F or both CF _{3 are} not included.

The double bonds of the formula -CY ¹ = CY ² - between the rings A ² to A ⁴ and optional double bonds in the groups Z ¹ and Z ⁵ preferably have the trans configuration (E configuration).

The compounds according to the invention have a high clearing point, a low melting point and a high optical anisotropy (Δn). The unwanted rotation of the compounds is limited so that they are particularly suitable for use in the gigahertz range. Advantageously, the relatively low loss factor in the microwave spectrum. The compounds alone or in mixture with other mesogenic components have a nematic phase over a broad temperature range. These properties make them particularly suitable for use in components for high frequency engineering, especially in liquid crystal phase shifters. Liquid-crystalline media according to the invention have the corresponding properties.

Preferred compounds of formula I are characterized by the selection of one or more of the following parameters:
The counter m is preferably 0 or 1, more preferably 0. The counter n is preferably 0 or 1, more preferably 0. m + n is preferably 0 or 1 and more preferably 0. m + n + p is preferably 1 or 2, ie the total number of ring systems in formula I is preferably 3 or 4.

The groups A ² , A ³ and A ⁴ preferably comprise a total of one or two bicyclic or tricyclic ring groups according to definition a). Particularly preferably, the group A ^{3 is} a ring group according to definition a). The ring groups A ² and A ⁴ , and A ¹ and A ^5, if present, are particularly preferably an optionally substituted ring group according to definition b) or c), in particular optionally substituted 1,4-phenylene.

The bridging groups Z ¹ and Z ⁵ are, independently of each other, preferably a single bond, -C≡C-, -CF = CF- or -CH = CH-, more preferably a single bond.

Z ² and Z ³ are preferably -C≡C- or -CF = CF-, more preferably -C≡C-. Among other things, these groups support a high Δn value and good phase properties. Y ¹ / Y ² are preferably H / F, F / H, F / F, Cl / F, CH ₃ / F, F / CH ₃ or F / Cl and more preferably F / F.

One or both of the radicals R ¹ or R ² , preferably R ¹ , preferably denotes a straight-chain alkyl radical having 1 to 15, in particular 2 to 15, C atoms, where in these radicals also one or more CH ₂ groups are in each case independently C≡C-, -CH = CH-, - (CO) O-, -O (CO) -, - (CO) -, -O- may be replaced so that O atoms are not directly linked to one another. The groups R ¹ and R ² are particularly preferably both an alkyl radical having 2 to 7 C atoms. Here, R ¹ and R ^{2 are,} for example, propyl and hexyl or butyl and butyl, furthermore propyl and pentyl, propyl and hexyl or butyl and pentyl.

In a further preferred embodiment of the invention, the group R ^{2 is} a polar group (radical X). The group R ² = X is in this case F, Cl, Br, CN, CF ₃ , OCF ₃ , SCN, NCS, SF ₅ or another halogenated alkyl radical having 1 to 9 C atoms, in which radical also one or more CH ₂ groups each independently of one another by -C≡C-, -CH = CH-, -CF = CF-, -CF = CH-, -CH = CF-, - (CO) O-, -O (CO) - , - (CO) -, -O- or -S- may be replaced so that O or S atoms are not directly linked to one another. R ² particularly preferably denotes F, CF ₃ or OCF ₃ . The corresponding compounds of the formula I have a clearly positive dielectric anisotropy (Δε). The Δε value is preferably 3 or more. The radical R ² therefore for both embodiments together preferably represents an alkyl radical having 2 to 15 C atoms, where in these radicals also one or more CH ₂ groups are each independently of one another by -C≡C-, -CH = CH-, - (CO) O-, -O (CO) -, - (CO) -, -O- can be replaced so that O atoms are not directly linked to one another, or F, Cl, Br, CN, CF ₃ , OCF ₃ , SCN, NCS, SF ₅ or a halogenated alkyl radical having 9 to 9 C-atoms, wherein in this radical also one or more CH ₂ groups each independently of one another by -C≡C-, -CH = CH-, -CF = CF-, -CF = CH-, -CH = CF-, - (CO) O-, -O (CO) -, - (CO) -, -O- or -S- may be replaced so that O - or S atoms are not directly linked.

The ring groups according to definition b) preferably have the partial structure

worin die Gruppen wie in Formel I definiert sind, insbesondere R¹ und R² unabhängig einen Alkylrest mit 2 bis 7 C-Atomen, beispielsweise einen Propylrest und die andere Gruppe einen Hexylrest oder beide Gruppen gleichzeitig einen Propyl-, Butyl-, Pentyl- oder Hexylrest bedeuten.Preferred embodiments of the invention are therefore represented by the following exemplary structures:

wherein the groups are as defined in formula I, in particular R ¹ and R ² independently an alkyl radical having 2 to 7 carbon atoms, for example a propyl radical and the other group a hexyl radical or both groups simultaneously a propyl, butyl, pentyl or Hexyl mean.

Schema 1: Syntheseschema zur Darstellung von Verbindungen der Formel I. The compounds of formula I can be advantageously prepared as shown in the following exemplary synthetic schemes (Scheme 1, 2). The symmetrical compounds of the formula I can be prepared by means of a simple Sonogashira reaction (Scheme 1):

Scheme 1: Synthetic scheme for the preparation of compounds of the formula I.

Schema 2: Syntheseschema zur Darstellung von asymmetrischen Verbindungen der Formel I. Asymmetric compounds of the formula (1) can be prepared in analogy to the reaction sequence shown in Scheme 2:

Scheme 2: Synthetic scheme for the preparation of asymmetric compounds of the formula I.

R ^1/2 in Scheme 1 and 2 have the meaning of R ^1/2 as defined for formula I. Schemes 1 and 2 show the synthesis of certain compounds. The phenyl radicals "R ¹ -phenyl" or "R ² -phenyl" can be assigned to any radicals -A ² - (Z ¹ -A ¹ ) _m -R ¹ or -A ⁴ - (Z ⁵ -A ⁵ ) generalize _n -R ² according to formula I. The parameters R ^1/2 , A ^1-5 , Z ^1/5 , m and n are defined therein as above and below.

The liquid-crystalline media according to the present invention comprise one or more compounds of the formula I and optionally at least one further, preferably mesogenic compound. The liquid-crystalline medium therefore preferably contains two or more compounds, which are preferably liquid-crystalline. Preferred media include the preferred compounds of formula I.

worin
L¹¹ R¹¹ oder X¹¹,
L¹² R¹² oder X¹²,
R¹¹ und R¹² unabhängig voneinander unfluoriertes Alkyl oder unfluoriertes Alkoxy mit 1 bis 17, bevorzugt mit 3 bis 10, C-Atomen oder unfluoriertes Alkenyl, unfluoriertes Alkinyl, unfluoriertes Alkenyloxy, oder unfluoriertes Alkoxyalkyl mit 2 bis 15, bevorzugt 3 bis 10, C-Atomen, vorzugsweise Alkyl oder unfluoriertes Alkenyl bedeuten,
X¹¹ und X¹² unabhängig voneinander F, Cl, Br, -CN, -NCS, -SCN, -SF₅, fluoriertes Alkyl oder fluoriertes Alkoxy mit 1 bis 7 C-Atomen oder fluoriertes Alkenyl, fluoriertes Alkenyloxy oder fluoriertes Alkoxyalkyl mit 2 bis 7 C-Atomen, vorzugsweise fluoriertes Alkoxy, fluoriertes Alkenyloxy, F oder Cl bedeuten,
p, q unabhängig 0 oder 1,
Z¹¹ bis Z¹³ unabhängig voneinander trans- -CH=CH-, trans- -CF=CF-, -C≡C- oder eine Einfachbindung bedeuten, und

unabhängig voneinander

worin L unabhängig verzweigtes oder unverzweigtes Alkyl, Alkenyl oder Alkinyl mit 1 bis 12 C-Atomen, worin unabhängig voneinander auch eine oder mehrere ”-CH₂-”-Gruppen durch O ersetzt sein können, C₃-C₆ Cycloalkyl, C₃-C₆ Cycloalkenyl, fluoriertes Alkyl oder Alkenyl, fluoriertes Alkyloxy oder Alkenyloxy, F, Cl, Br, CN, NCS, SCN oder SF₅, bedeutet,
bedeuten.Further components of the liquid-crystalline media are preferably selected from the compounds of the formula II:

wherein
L ¹¹ R ¹¹ or X ¹¹ ,
L ¹² R ¹² or X ¹² ,
R ¹¹ and R ¹² are each independently of one another unfluorinated alkyl or unfluorinated alkoxy having 1 to 17, preferably 3 to 10, C atoms or unfluorinated alkenyl, unfluorinated alkynyl, unfluorinated alkenyloxy, or unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C Atoms, preferably alkyl or unfluorinated alkenyl,
X ¹¹ and X ¹² independently of one another are F, Cl, Br, -CN, -NCS, -SCN, -SF ₅ , fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms or fluorinated alkenyl, fluorinated alkenyloxy or fluorinated alkoxyalkyl having 2 to 7 C atoms, preferably fluorinated alkoxy, fluorinated alkenyloxy, F or Cl,
p, q independently 0 or 1,
Z ¹¹ to Z ^{13 are} independently of one another trans- CH = CH-, trans- -CF = CF-, -C≡C- or a single bond, and

independently of each other

in which L is independently branched or unbranched alkyl, alkenyl or alkynyl having 1 to 12 C atoms, in which independently of one another one or more "-CH ₂ -" groups may be replaced by O, C ₃ -C ₆ cycloalkyl, C ₃ - C ₆ denotes cycloalkenyl, fluorinated alkyl or alkenyl, fluorinated alkyloxy or alkenyloxy, F, Cl, Br, CN, NCS, SCN or SF ₅ ,
mean.

In a preferred embodiment of the present invention, the liquid-crystalline media comprise one or more compounds of the formula I and one or more compounds of the formula II.

According to the present application, the liquid-crystalline media preferably contain a total of 5 to 95%, preferably 10 to 90% and particularly preferably 15 to 80%, of compounds of the formula I.

Preferably, the liquid-crystalline media according to the present invention contain compounds selected from the group of the compounds of formulas I and II, more preferably they are predominantly, even more preferably they are substantially and quite preferably they consist entirely thereof.

In this application, "contained" in the context of compositions means that the entity in question, i. H. the medium or component, the specified component or components or compound or compounds, preferably in a total concentration of 10% or more, and more preferably 20% or more.

"Predominantly" in this context means that the entity in question contains 55% or more, preferably 60% or more and most preferably 70% or more of the indicated component or components or compound or compounds.

"Substantially" in this context means that the entity in question contains 80% or more, preferably 90% or more, and most preferably 95% or more of the stated component or components or compound or compounds.

"Complete" in this context means that the entity in question contains 98% or more, preferably 99% or more and most preferably 100.0% of the indicated component or components or compound or compounds.

According to the present application, the liquid-crystalline media preferably contain a total of 10 to 100%, preferably 20 to 95% and particularly preferably 25 to 90%, of compounds of the formulas I and II.

According to the present invention, the compounds of formula II are preferably present in a total concentration of from 10% to 90%, more preferably from 15% to 85%, even more preferably from 25% to 80% and most preferably from 30% to 75% of the total mixture used.

The liquid-crystalline media may also contain other additives such as stabilizers, chiral dopants and nanoparticles. The individual compounds added are used in concentrations of 0.005 to 6%, preferably from 0.1 to 3%. The total concentration of these other ingredients is in the range of 0% to 10%, preferably 0.1% to 6%, based on the total mixture. However, the concentration data of the other constituents of the liquid-crystal mixtures, ie the liquid-crystalline or mesogenic compounds, are given without consideration of the concentration of these additives.

The liquid-crystalline media preferably contain 0 to 10% by weight, in particular 0.01 to 5% by weight and more preferably 0.1 to 3% by weight, of stabilizers. Preferably, the media contain one or more stabilizers selected from 2,6-di-tert-butylphenols, 2,2,6,6-tetramethylpiperidines or 2-benzotriazol-2-yl-phenols. These adjuvants are known in the art and commercially available, for. B. as a sunscreen.

An embodiment of the invention is therefore also a process for the preparation of a liquid-crystal medium, which is characterized in that one or more compounds of the formula I is mixed with one or more further compounds and optionally with one or more additives. The further compounds are preferably selected from the compounds of the formula II, as indicated above, and optionally one or more further compounds.

In the present application, the term dielectrically positive describes compounds or components with Δε> 3.0, dielectrically neutral with -1.5 ≤ Δε ≤ 3.0 and dielectrically negative with Δε <-1.5. The dielectric anisotropy of each compound is determined from the results of a solution of 10% of each individual compound in a nematic host mixture. If the solubility of each compound in the host mixture is less than 10%, the concentration is reduced to 5%. The capacities of the test mixtures are determined in a cell with homeotropic as well as homogeneous orientation. The layer thickness is about 20 μm for both cell types. The applied voltage is a square wave with a frequency of 1 kHz and an effective value of typically 0.5V to 1.0V, but is always chosen to be below the capacitive threshold for the particular test mixture.

Δε is defined as (ε _|| - ε _⊥ ), while ε is _average (ε _|| + 2ε _⊥ ) / 3.

As a host mixture, the mixture ZLI-4792 is used for dielectrically positive compounds and the mixture ZLI-3086 for dielectrically neutral as well as for dielectrically negative compounds, both from Merck KGaA, Germany. The absolute values of the dielectric constants of the compounds are determined from the change in the respective values of the host mixture upon addition of the compounds of interest. The values are extrapolated to a concentration of the compounds of interest of 100%.

Components which have a nematic phase at the measuring temperature of 20 ° C are measured as such, all others are treated as compounds.

The term threshold voltage in the present application refers to the optical threshold and is given for 10% relative contrast (V ₁₀ ), the term saturation voltage refers to optical saturation and is given for 90% relative contrast (V ₉₀ ), in both cases, if not expressly stated otherwise. The capacitive threshold voltage (V ₀ ), also called the Freedericks threshold V _Fr , is only used if expressly stated.

The parameter ranges given in this application all include the limits unless expressly stated otherwise.

The different upper and lower limits given for different ranges of properties provide additional preferred ranges in combination.

Throughout this application, the following terms and definitions apply unless expressly stated otherwise. All concentrations are given in percentage by weight and refer in each case to the total mixture, all temperatures and all temperature differences are given in degrees Celsius or degree of difference. All physical properties typical of liquid crystals are reduced "Merck Liquid Crystals, Physical Properties of Liquid Crystals", as of Nov. 1997, Merck KGaA, Germany , and are listed for a temperature of 20 ° C, unless otherwise stated. The optical anisotropy (Δn) is determined at a wavelength of 589.3 nm. The dielectric anisotropy (Δε) is determined at a frequency of 1 kHz. The threshold voltages as well as all other electro-optical properties are determined with test cells manufactured at Merck KGaA, Germany. The test cells for the determination of Δε have a layer thickness of approximately 20 μm. The electrode is a circular ITO electrode with a surface area of 1.13 cm ² and a guard ring. The alignment layers are SE-1211 from Nissan Chemicals, Japan, for homeotropic alignment (ε _|| ) and polyimide AL-1054 from Japan Synthetic Rubber, Japan, for homogeneous alignment (ε _⊥ ). Capacitance is determined with a Salatron 1260 frequency response analyzer using a sine wave with a voltage of 0.3 V. The light used in the electro-optical measurements is white light. In this case, a structure with a commercially available device DMS Fa. Autronic Melchers, Germany is used. The characteristic stresses are determined under vertical observation. The threshold voltage (V ₁₀ ), mid-gray voltage (V ₅₀ ) and saturation voltage (V ₉₀ ) are determined for 10%, 50% and 90% relative contrast, respectively.

The liquid-crystalline media are examined for their properties in the frequency range of microwaves as in A. Penirschke et al. "Cavity Perturbation Method for Characterization of Liquid Crystals up to 35 GHz", 34th European Microwave Conference Amsterdam, pp. 545-548 describe. See also Gaebler et al. "Direct Simulation of Material Permittivities ...", 12MTC 2009 - International Instrumentation and Measurement Technology Conference, Singapore, 2009 (IEEE), pp. 463-467 and DE 10 2004 029 429 A , in which also a measuring method is described in detail.

The liquid crystal is filled in a capillary made of polytetrafluoroethylene (PTFE) or quartz glass. The capillary has an inner radius of 180 μm and an outer radius of 350 μm. The effective length is 2.0 cm. The filled capillary is placed in the center of the cylindrical cavity with a resonant frequency of 19 GHz. This cavity has a length of 11.5 mm and a radius of 6 mm. Thereafter, the input signal ("source") is applied and the result of the output signal is recorded with a commercial network analyzer ("vector network analyzer"). For other frequencies, the dimensions of the cavity are adjusted accordingly.

From the change of the resonance frequency and the Q factor, between the measurement with the capillary filled with the liquid crystal and the measurement without the capillary filled with the liquid crystal, the dielectric constant and the loss angle at the corresponding target frequency are calculated by means of equations 10 and 11 of FIG previously mentioned document A. Penirschke et al., 34th European Microwave Conference - Amsterdam, pp. 545-548 determined, as described there.

The values for the components of the properties perpendicular to and parallel to the director of the liquid crystal are obtained by orienting the liquid crystal in a magnetic field. For this purpose, the magnetic field of a permanent magnet is used. The strength of the magnetic field is 0.35 Tesla. The orientation of the magnet is adjusted accordingly and then rotated accordingly by 90 °.

The dielectric anisotropy in the μ-wave range is defined as Δε _r ≡ (ε _{r, ||} - ε _{r, ⊥} ).

The modulability or controllability ("tuneability", τ) is defined as τ ≡ (Δε _r / ε _{r, ||} ).

mit dem maximalen dielektrischen Verlustfaktor tan

der aus dem Maximalwert der gemessenen Werte für tan

hervorgeht.The material quality (η) is defined as

with the maximum dielectric loss factor tan

from the maximum value of the measured values for tan

evident.

The material quality (η) of the preferred liquid crystal materials is 6 or more, preferably 7 or more, preferably 10 or more, preferably 15 or more, more preferably 25 or more and most preferably 30 or more.

The preferred liquid crystal materials have in the respective components phase shifters of 15 ° / dB or more, preferably 20 ° / dB or more, preferably 30 ° / dB or more, preferably 40 ° / dB or more, preferably 50 ° / dB or more, more preferably 80 ° / dB or more, and most preferably 100 ° / dB or more.

The liquid-crystal media according to the invention preferably have nematic phases of at least -20.degree. C. to 80.degree. C., preferably -30.degree. C. to 85.degree. C., and very particularly preferably -40.degree. C. to 100.degree. Particularly preferably, the phase is up to 120 ° C or more, preferably up to 140 ° C or more, and most preferably up to 180 ° C or more. In this case, the term "nematic phase" means, on the one hand, that no smectic phase and no crystallization are observed at low temperatures at the corresponding temperature and, on the other hand, that clarification does not yet occur on heating from the nematic phase. The investigation at low temperatures is carried out in a flow viscometer at the appropriate temperature and checked by storage in test cells, with a layer thickness of 5 microns, for at least 100 hours. At high temperatures, the clearing point is measured in capillaries by conventional methods.

The liquid crystal media according to the present invention preferably have a clearing point of 90 ° C or more, more preferably 100 ° C or more, even more preferably 120 ° C or more, more preferably 150 ° C or more, and most preferably 170 ° C or more, up.

The Δε of the liquid crystal medium according to the invention at 1 kHz and 20 ° C is preferably 1 or more, more preferably 2 or more, and most preferably 3 or more.

The Δn of the liquid crystal media according to the present invention is preferably 589 nm (Na ^D ) and 20 ° C in the range of 0.20 or more to 0.90 or less, more preferably in the range of 0.25 or more to 0.90 or less, more preferably in the range of 0.30 or more to 0.85 or less and most preferably in the range of 0.35 or more to 0.80 or less.

In a preferred embodiment of the present application, the Δn of the liquid crystal media according to the present invention is preferably 0.50 or more, more preferably 0.55 or more.

Furthermore, the liquid-crystal media according to the invention are characterized by high anisotropies in the microwave range. The birefringence is z. B. at about 8.3 GHz, preferably 0.14 or more, more preferably 0.15 or more, more preferably 0.20 or more, more preferably 0.25 or more and most preferably 0.30 or more. In addition, the birefringence is preferably 0.80 or less.

The liquid crystals used are either individual substances or mixtures. Preferably, they have a nematic phase.

In the present application, unless expressly stated otherwise, the term compounds means both one compound and several compounds.

Preferred devices containing a liquid crystal medium or at least one compound according to the invention are phase shifters, varactors, antenna arrays (eg for radio, cellular, radio, microwave / radar and other data transmission), matching circuit adaptive filters and others. Preference is given to components for high-frequency technology, as defined above. Preference is also given by different applied electrical voltages modulatable components. Very particularly preferred components are tunable phase shifters. In preferred embodiments, a plurality of phase shifters are operatively connected, thereby providing, for example, a phased array antenna, typically called a 'phased array'. Antenna designates, results. A group antenna uses the phase shift of the transmitting or receiving elements arranged in a matrix, in order to achieve bundling by interference. A so-called 'phased array' can be constructed from a row or grid-shaped parallel arrangement of phase shifters, which can serve as a tunable or passive transmitting or receiving antenna for high frequencies (eg gigahertz range). Inventive 'phased array' antennas have a very wide usable receiving cone.

Preferred applications are radar installations and data transmission equipment on manned or unmanned vehicles in the automotive, shipping, aircraft, aerospace and satellite industries.

For the production of suitable components for high-frequency technology, in particular suitable phase shifter, a liquid-crystalline medium according to the invention is typically introduced into rectangular cavities of less than 1 mm thickness, several mm wide and several centimeters long. The cavities have opposing electrodes mounted along two long sides. Such arrangements are familiar to the skilled person. By applying a variable voltage when operating the antenna, the dielectric properties of the liquid-crystalline medium can be tuned to set different frequencies or directions of an antenna.

The term "halogen" or "halogenated" stands for F, Cl, Br and I, especially for F and Cl and especially for F.

The term "alkyl" preferably comprises straight-chain and branched alkyl groups having 1 to 15 carbon atoms, in particular the straight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl. Groups of 2 to 10 carbon atoms are generally preferred.

The term "alkenyl" preferably comprises straight-chain and branched alkenyl groups having 2 to 15 carbon atoms, in particular the straight-chain groups. Particularly preferred alkenyl groups are C ₂ to C ₇ -1E-alkenyl, C ₄ to C ₇ -3E-alkenyl, C ₅ to C ₇ -4-alkenyl, C ₆ to C ₇ -5-alkenyl and C ₇ -6-alkenyl , in particular C ₂ to C ₇ -1E-alkenyl, C ₄ to C ₇ -3E-alkenyl and C ₅ to C ₇ -4-alkenyl. Examples of further preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl , 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Groups of up to 5 carbon atoms are generally preferred.

The term "alkoxy" preferably comprises straight-chain radicals of the formula C _n H _{2n + 1} -O-, where n is 1 to 10. N is preferably 1 to 6. Preferred alkoxy groups are, for example, methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy, n-nonoxy, n-decoxy.

The expression "oxaalkyl" or "alkoxyalkyl" preferably comprises straight-chain radicals of the formula C _n H _{2n + 1} -O- (CH ₂ ) _m , in which n and m are each independently of one another 1 to 10. Preferably, n is 1 and m is 1 to 6.

The term "fluorinated alkyl" preferably includes mono- or polyfluorinated radicals. Perfluorinated radicals are included. Particularly preferred are CF ₃ , CH ₂ CF ₃ , CH ₂ CHF ₂ , CHF ₂ , CH ₂ F, CHFCF ₃ and CF ₂ CHFCF ₃ .

The term "fluorinated alkoxy" includes mono- or polyfluorinated radicals. Perfluorinated radicals are preferred. Particularly preferred is the radical OCF ₃ .

The term "alk (en / yn) yl groups wherein one or more" -CH ₂ - "groups may be replaced by -O-" preferably refers to those groups wherein a non-terminal CH ₂ group is replaced. OH groups are included in the general meaning.

The term "substituted cycloalkyl" embraces mono- or polysubstituted alkyl-substituted cycloalkyl, especially alkyl of 1 to 8 carbon atoms.

The term "substituted phenyl" includes phenyl which is monosubstituted or polysubstituted by a group such as R ¹ , in particular phenyl which is substituted by F, Cl, alkyl or alkoxy.

In the present application, high frequency engineering means applications with frequencies in the range of 1 MHz to 10 THz, preferably from 1 GHz to 3 THz, more preferably 2 GHz to 1 THz, most preferably from 5 to 300 GHz. The application is preferably in the microwave spectrum or adjacent areas suitable for message transmission, in which 'phased array' modules can be used in transmitting and receiving antennas.

The liquid-crystal media according to the invention consist of one or more compounds, preferably from 2 to 30, more preferably from 3 to 20 and most preferably from 3 to 16 compounds. These compounds are mixed in a conventional manner. In general, the desired amount of the compound used in the smaller amount is dissolved in the compound used in the larger amount.

If the temperature is above the clearing point of the compound used in the higher concentration, the completion of the dissolution process is particularly easy to observe. However, it is also possible, the media in other conventional ways, for example using so-called premixes, which may be z. B. may be homologous or eutectic mixtures of compounds, or using so-called "multi-bottle" systems whose ingredients are themselves ready mixtures. All temperatures, such. B. the melting point T (K, N) or T (K, S), the transition from the smectic (S) to the nematic (N) phase T (S, N) and the clearing point T (N, I) of the liquid crystals are given in degrees Celsius. All temperature differences are indicated in degrees of difference.

In the present application and in the following examples, the structures of the liquid crystal compounds are indicated by acronyms, wherein the transformation into chemical formulas according to following Tables A and B takes place. All radicals C _n H _{2n + 1} and C _m H _{2m + 1} are straight-chain alkyl radicals with n or m C atoms; n, m and k are integers and are preferably 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12. The coding according to Table B is self-evident. In Table A only the acronym for the main body is given. In individual cases, followed by asterisks, a code for the substituents R ^{1 *} , R ^{2 *} , L ^{1 *} and L ^{2 *} follows separately from the acronym for the main body: Code for R ^{1 *} , R ^{2 *} , L ^{1 *} , L2 *, L ^{3 *} R ^{1 *} R ^{2 *} L ^{1 *} L ^{2 *} nm C _n H _{2n + 1} C _m H _{2m + 1} H H n Om C _n H _{2n + 1} OC _m H _{2m + 1} H H nO.m OC _n H _{2n + 1} C _m H _{2m + 1} H H n C _n H _{2n + 1} CN H H nN.F C _n H _{2n + 1} CN F H nN.FF C _n H _{2n + 1} CN F F nF C _n H _{2n + 1} F H H n Cl C _n H _{2n + 1} Cl H H nOF OC _n H _{2n + 1} F H H nF.F C _n H _{2n + 1} F F H nF.FF C _n H _{2n + 1} F F F nOCF ₃ C _n H _{2n + 1} OCF ₃ H H nOCF ₃ .F C _n H _{2n + 1} OCF ₃ F H n-Vm C _n H _{2n + 1} -CH = CH-C _m H _{2m + 1} H H nV-Vm C _n H _{2n + 1} -CH = CH -CH = CH-C _m H _{2m + 1} H H

Tabelle B

Suitable mixture components can be found in Tables A and B. TABLE A

Table B

The following examples illustrate the present invention without limiting it in any way.

From the physical properties, however, it will be apparent to those skilled in the art which properties can be achieved and in which areas they are modifiable. In particular, therefore, the combination of the various properties that can preferably be achieved, well defined for the expert.

In the present application, unless expressly stated otherwise, the plural form of a term means both the singular form and the plural form, and vice versa. Further combinations of the embodiments and variants of the invention according to the description will become apparent from the appended claims. Used abbreviations: MTB Methyl tert-butyl ether SiO ₂ silica gel RT Room temperature (about 20 ° C)

Examples

The acetylenes and boronic acids used are commercially available or can be prepared analogously to known syntheses which are known to the person skilled in the art. The radicals "C ₄ H ₉ " stand for unbranched n-butyl radicals. The same applies to C ₃ H ₇ , C ₆ H ₁₃ , etc. Synthesis Example 1: Synthesis of 1,4-bis (4-n-butylphenylethynyl) phthalazine

10 g (50 mmol) of 1,4-dichlorophthalazine and 18 g (114 mmol) of 4-n-butylphenylacetylene are initially charged in 250 ml of triethylamine, with 200 mg (1 mmol) of copper (I) iodide and 700 mg (1 mmol ) Added bis (triphenylphosphine) palladium (II) chloride and refluxed for 1.5 h. The mixture is cooled, treated with water and toluene and the phases separated. The organic phase is washed once with saturated ammonium chloride solution and once with saturated sodium chloride solution, dried over sodium sulfate, filtered off and concentrated on a rotary evaporator. The residue is purified by column chromatography (SiO ₂ , toluene → toluene / ethyl acetate = 10: 1). Further purification is carried out by recrystallization from toluene or toluene-heptane mixtures.
MS (EI): m / z (%) = 442 (100, M ⁺ ), 414 (13), 399 (13), 328 (11), 313 (9).
Δε = -3.2
Δn = 0.41
γ ₁ = 3475 mPa · s
K 148 N 179 I

MS (EI): m/z (%) = 448 (100, M⁺), 405 (35, [M – Propyl]⁺), 362 (22, [M – 2 Propyl]⁺), 181 (10, [M – 2 Propyl]²⁺).
Δε = +1,3
Δn = 0,48
γ₁ = 1703 mPa·s
K 87 N 165 I 3) 4,7-Bis-(4-n-Butyl-phenylethynyl)-indan

MS (EI): m/z (%) = 430 (100, M⁺), 387 (25, [M – Propyl]⁺), 344 (8, [M – 2 Propyl]⁺), 172 (12, [M – 2 Propyl]²⁺).
Δε = +1,7
Δn = 0,42
γ₁ = 1532 mPa·s
K 109 N 178 I 4) 5,8-Bis-(4-n-Butyl-phenylethynyl)-1,2,3,4-tetrahydronaphthalin

MS (EI): m/z (%) = 444 (100, M⁺), 401 (15, [M – Propyl]⁺).
Δε = +2,4
Δn = 0,39
γ₁ = 3238 mPa·s
K 77 N 160 I 5) 5,8-Bis-(4-n-Butyl-phenylethynyl)-chinolin

MS (EI): m/z (%) = 441 (100, M⁺), 398 (40, [M – Propyl]⁺), 355 (20, [M – 2 Propyl]⁺), 177,5 (13, [M – 2 Propyl]²⁺).
Δε = +6,5
Δn = 0,44
γ₁ = 3347 mPa·s
K 85 N 152 I 6a) 3',6'-Ditrifluormethansulfonyl-benzonorbornan

Analogously, the following Examples 2 to 5 are synthesized: 2) 4,7-bis- (4-n-butylphenylethynyl) -2,1,3-benzothiadiazole, (2)

MS (EI): m / z (%) = 448 (100, M ⁺ ), 405 (35, [M-propyl] ⁺ ), 362 (22, [M-2-propyl] ⁺ ), 181 (10, M - 2 propyl] ²⁺ ).
Δε = +1.3
Δn = 0.48
γ ₁ = 1703 mPa · s
K 87 N 165 I 3) 4,7-bis- (4-n-butylphenylethynyl) -indane

MS (EI): m / z (%) = 430 (100, M ⁺ ), 387 (25, [M-propyl] ⁺ ), 344 (8, [M-2-propyl] ⁺ ), 172 (12, M - 2 propyl] ²⁺ ).
Δε = +1.7
Δn = 0.42
γ ₁ = 1532 mPa · s
K 109 N 178 I 4) 5,8-Bis- (4-n-butylphenylethynyl) -1,2,3,4-tetrahydronaphthalene

MS (EI): m / z (%) = 444 (100, M ⁺ ), 401 (15, [M-propyl] ⁺ ).
Δε = +2.4
Δn = 0.39
γ ₁ = 3238 mPa · s
K 77 N 160 I 5) 5,8-Bis- (4-n-butylphenylethynyl) quinoline

MS (EI): m / z (%) = 441 (100, M ⁺ ), 398 (40, [M-propyl] ⁺ ), 355 (20, [M-2-propyl] ⁺ ), 177.5 (13 , [M-2-propyl] ²⁺ ).
Δ∈ = + 6.5
Δn = 0.44
γ ₁ = 3347 mPa · s
K 85 N 152 I 6a) 3 ', 6'-Ditrifluoromethanesulfonylbenzonorbornane

4 g (22 mmol) of 3 ', 6'-dihydroxy-benzonorbornan are initially charged in 80 ml of dichloromethane, mixed with 15 ml (108 mmol) of triethylamine and 102 mg (0.8 mmol) of 4-dimethylamino-pyridine and cooled in an ice bath. Thereafter, 17.5 g (61 mmol) of trifluoromethanesulfonic anhydride are added dropwise, and the mixture is stirred overnight while heating to RT. Subsequently, water is added carefully and the phases are separated. The organic phase is washed with water and saturated sodium bicarbonate solution, dried over sodium sulfate, filtered off and concentrated on a rotary evaporator. The residue is purified by column chromatography (SiO ₂ , dichloromethane); the product is obtained as a yellow oil. 6b) 3 ', 6'-bis (4-n-butyl-phenylethynyl) -benzonorbornane

MS (EI): m/z (%) = 446 (100, M⁺), 403 (35, [M – Propyl]⁺), 360 (22, [M – 2 Propyl]⁺), 180 (16, [M – 2 Propyl]²⁺).
Δε = +3,1
Δn = 0,50
γ₁ = 1494 mPa·s
K 99 N 224 I 7.1 g (42 mmol) of 4-n-butyl-phenylacetylene are initially charged in 50 ml of tetrahydrofuran, cooled to -75 ° C and treated with 42 ml (1.0 M in hexane, 42 mmol) Lithiumhexamethyldisilazid. After 1 h, 42 ml (1.0 M in hexane, 42 mmol) of B-methoxy-9-borabicyclo [3.3.1] nonane are added and stirred for an additional hour. The mixture is then heated to -20 ° C, with 500 mg (0.55 mmol) of tris (dibenzylideneaceton) dipalladium, 160 mg (0.39 mmol) of 2-dicyclohexylphosphino-2'-6'-dimethoxybiphenyl and 8.5 g (19 mmol) of the triflate obtained in the previous reaction in 50 ml of tetrahydrofuran and refluxed for 16 h. The workup is carried out by adding MTB and water, the phases are separated and the aqueous phase is extracted once with MTB. The combined organic phases are washed with saturated Natriumchloridlsg. washed, dried over sodium sulfate, filtered off and concentrated on a rotary evaporator. The residue is purified by column chromatography (SiO ₂ , heptane / toluene = 9: 1); the product is obtained as an orange solid. The further purification is carried out by recrystallization from isopropanol and ethanol-toluene mixtures.
MS (EI): m / z (%) = 456 (100, M ⁺ ), 428 (46, [M-ethylene] ⁺ ), 413 (8, [M-propyl] ⁺ ), 385 (30, [M - ethylene - propyl] ⁺ ).
Δε = +0.6
Δn = 0.34
γ ₁ = 5504 mPa · s
Tg - 18 K 95 N 105 I 7) 2,6-Bis- (4-n-butylphenylethynyl) benzthiophene (7)

MS (EI): m / z (%) = 446 (100, M ⁺ ), 403 (35, [M-propyl] ⁺ ), 360 (22, [M-2-propyl] ⁺ ), 180 (16, M - 2 propyl] ²⁺ ).
Δε = +3.1
Δn = 0.50
γ ₁ = 1494 mPa · s
K 99 N 224 I

Mixing Example 1

A liquid crystal medium M-1 having the composition and properties as shown in the following table is prepared. The compound (2) (No. 15) is from Synthesis Example 2. composition Physical Properties connection T (N, I) = 99.5 ° C Δn (20 ° C, 589.3 nm) = 0.135 Δε (20 ° C, 1 kHz) = 4.9 No. abbreviation 1 BGH 3F.F 10.8% 2 BCH 5F.F 9.00% 3 ECCP 30CF3 4.50% 4 ECCP 50CF3 4.50% 5 CBC-33F 1.80% 6 CBC-53F 1.80% 7 CBC-55F 1.80% 8th PCH-6F 7.20% 9 PCH-7F 5.40% 10 CCP 20CF3 7.20% 11 CCP 30CF3 10.8% 12 CCP 40CF3 6.30% 13 CCP 50CF3 9.90% 14 PGH-5F 9.00% 15 (2) 10.0% Σ 100.0%

This mixture is used for applications in the microwave range, in particular for phase shifters for 'phased array' antennas.

For comparison, a medium C-1 without the component (2) is prepared from the compounds Nos. 1-14 of the medium M-1, wherein the compounds Nos. 1-14 are contained in the same relative amounts.

Mixture example 2

A liquid-crystal medium M-2 having the composition of M-1 is prepared, except that the compound (7) of Synthesis Example 7 is used instead of the compound (2).

The results for mixture examples 1 and 2 can be found in the following table. Table: Properties of Mixtures M-1, M-2 and C-1 (Comparison) at 19 GHz (20 ° C)

) und die Materialgüte η sind jeweils gegenüber der Vergleichsmischung C-1 deutlich verbessert.The controllability τ, the maximum loss factor (here tan

) and the material quality η are each significantly improved over the comparison mixture C-1.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0968988 A1 [0003]
• DE 19907941 A1 [0003]
• DE 10120024 A1 [0003]
• JP 08012599 A [0003]
• DE 102004029429 A [0004, 0009, 0055]
• JP 2005-120208 (A) [0004]
• EP 2073290 A1 [0010, 0010]
• WO 20081021208 A2 [0010]
• JP 2004-082439A [0010]

Cited non-patent literature

• A. Gaebler, A. Moessinger, F. Goelden, et al., "Liquid Crystal-Reconfigurable Antenna Concepts for Space Applications at Microwave and Millimeter Waves," International Journal of Antennas and Propagation, vol. 2009, Article ID 876989, 7 pages, 2009. doi: 10.1155 / 2009/876989 [0005]
• A. Penirschke, S. Müller, P. Scheele, C. Weil, M. Wittek, C. Hock and R. Jakoby: "Cavity Perturbation Method for Characterization of Liquid Crystals up to 35 GHz", 34th European Microwave Conference - Amsterdam, 545-548 [0006]
• S.-T. Wu, C.-S. Hsu, K.-F. Shyu Appl. Phys. Lett. (1999), 74 (3), 344-346 [0007]
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• A. Penirschke et al. "Cavity Perturbation Method for Characterization of Liquid Crystals up to 35 GHz", 34th European Microwave Conference Amsterdam, pp. 545-548 [0055]
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Claims (16)

Compounds of the formula I R ¹ - (A ¹ -Z ¹ ) _m -A ² -Z ² - (A ³ ) _p -Z ³ -A ⁴ - (Z ⁵ -A ⁵ ) _n -R ² I wherein A ^{1-5 are} independently, optionally bilaterally, a) a group of the formulas

wherein X is O, S, SO, SO ₂ , NH, NR ³ or NO, one or two non-adjacent -CH ₂ - may be replaced by X, and R ³ is defined as R ¹ , b) 1,4-phenylene, wherein one or more, preferably one to two CH groups may be replaced by N, c) a radical of the formulas

d) trans-1,4-cyclohexylene or cyclohexenylene, in which also one or two non-adjacent CH ₂ groups may be replaced by -O- and / or -S-, and in which H may be replaced by F, or e) a Residue from the group 1,4-bicyclo (2,2,2) octyl, cyclobutane-1,3-diyl, spiro [3.3] heptane-2,6-diyl, thiophene-2,5-diyl, thiophene-2 , 4-diyl, furan-2,5-diyl, furan-2,4-diyl, and in which groups a), b), c), d) and e) also have one or more H atoms towards Br, Cl, F, CN, -NCS, -SCN, SF ₅ , C ₁ -C ₁₀ alkyl, C ₁ -C ₁₀ alkoxy, C ₃ -C ₆ cycloalkyl or a mono- or polyfluorinated C ₁ -C ₁₀ alkyl or Alkoxy group may be replaced, and wherein at least one radical of A ² , A ³ and A ^{4 is} a radical according to a), R ¹ and R ^{2 are} each independently a halogenated or unsubstituted alkyl radical having 1 to 15 carbon atoms, wherein in these Also one or more CH ₂ groups each independently of one another by -C≡C-, -CH = CH-, -CF = CF-, -CF = CH-, -CH = CF-, - (CO) O-, -O (CO) -, - (CO) -, -O- or -S- may be replaced so that O or S atoms are not directly linked to each other, F, Cl, Br, CN, CF ₃ , OCF ₃ , SCN, NCS or SF ₅ , Z ² , Z ³ independently of one another -C≡C- or

Y ¹ , Y ² independently of one another are H, F, Cl, C ₁ -C ₁₀ -alkyl, Z ¹ , Z ⁵ independently of one another a single bond, -C≡C-, -CH = CH-, -CH ₂ O-, - ( CO) O-, -CF ₂ O-, -CF ₂ CF ₂ -, -CH ₂ CF ₂ -, -CH ₂ CH ₂ -, - (CH ₂ ) ₄ -, -CH = CF- or -CF = CF - where asymmetric bridges may be oriented to either side, p 1 or 2, and m, n independently of one another 0, 1 or 2, or R ¹ - (A ¹ -Z ¹ ) _m -A ² - or -A ⁴ - (Z ⁵ -A ⁵ ) _n -R ² independently optionally also a radical of the formulas

mean. Compounds according to claim 1, characterized in that the group A ^{3 of} the formula I is a radical according to definition a). Compounds according to claim 1 or 2, characterized in that p is 1. Compounds according to one or more of claims 1 to 3, characterized in that compounds of the formulas

wherein R ¹ and R ^{2 are} both CH ₃ , both F or both CF _{3 are} not included. Compounds according to one or more of claims 1 to 4, characterized in that the rings A ² and A ^{4 is} an optionally substituted 1,4-phenylene ring. Compounds according to one or more of claims 1 to 5, characterized in that m and n represent 0. Liquid-crystal medium, characterized in that it contains one or more compounds of the formula I according to one of claims 1 to 6. Liquid-crystal medium according to claim 7, characterized in that it additionally contains one or more compounds selected from the compounds of formula II:

wherein: L ¹¹ R ¹¹ or X ¹¹ , L ¹² R ¹² or X ¹² , R ¹¹ and R ^{12 are} independently of each other unfluorinated alkyl or unfluorinated alkoxy having 1 to 17 carbon atoms or unfluorinated alkenyl, unfluorinated alkynyl, unfluorinated alkenyloxy, or unfluorinated Alkoxyalkyl having 2 to 15 carbon atoms, X ¹¹ and X ¹² independently of one another F, Cl, Br, -CN, -NCS, -SCN, -SF ₅ , fluorinated alkyl or fluorinated alkoxy having 1 to 7 carbon atoms or fluorinated alkenyl , fluorinated alkenyloxy or fluorinated alkoxyalkyl of 2 to 7 carbon atoms, p, q are independently 0 or 1, Z ¹¹ to Z ^{13 are} independently of one another trans- CH = CH-, trans- -CF = CF-, -C≡C- or a single bond, and

independently of each other

wherein L is independently branched or unbranched alkyl, alkenyl or alkynyl having 1 to 12 C atoms, wherein independently of one another one or more "-CH ₂ -" - groups may be replaced by O, C ₃ -C ₆ Cycloalkyl, C ₃ -C ₅ cycloalkenyl, fluorinated alkyl or alkenyl, fluorinated alkyloxy or alkenyloxy, F, Cl, Br, CN, NCS, SCN or SF ₅ , Liquid-crystal medium according to Claim 7 or 8, characterized in that the concentration of the compounds of the formula I in the medium is in the range from 5% to 95% overall. Use of the compounds of the formula I according to one of claims 1 to 6 in a liquid-crystalline medium. Use of the compounds of the formula I according to one of Claims 1 to 6 in a component for high-frequency engineering. Process for the preparation of a liquid-crystal medium according to one or more of Claims 7 to 9, characterized in that one or more compounds of the formula I is mixed with one or more further compounds and optionally with one or more additives. Component for high-frequency technology, characterized in that it contains a liquid-crystal medium according to one or more of claims 7 to 9. Component according to claim 13, characterized in that it is one or more functionally connected phase shifter. Use of a liquid-crystal medium according to one or more of Claims 7 to 9 in a component for high-frequency engineering. 'Phased array' antenna, characterized in that it contains one or more components according to claim 13 or 14.