AROMATIC ISOTHIOCYANATES

Abstract

The present invention relates to a liquid crystal medium comprising aromatic isothiocyanates of formula C

##STR00001##

as defined in claim 1, and to high-frequency components comprising these media, especially microwave components for high-frequency devices, such as devices for shifting the phase of microwaves, tunable filters, tunable metamaterial structures, and electronic beam steering antennas, e.g. phased array antennas.

Claims

1. A liquid crystal medium comprising a) a compound of formula C ##STR00455## in which R.sup.C1 denotes H, straight-chain or branched alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms, in which one or more CH.sub.2-groups may be replaced by ##STR00456## where one or more non-adjacent CH.sub.2-groups may be replaced by O and where one or more H atoms may be replaced by F, Z.sup.C2 denotes CHCH, CFCF, CHCF, CFCH or CC, X.sup.1, X.sup.2 identically or differently, denote H, Cl, F or methyl, Y denotes H, Cl, F, or alkyl or alkoxy each having 1 to 6 C atoms, ##STR00457## identically or differently, denote ##STR00458## R.sup.C2 denotes H, CH.sub.3 or F, and c is 0 or 1, and b) one or more compounds selected from the group of compounds of the formulae I, II and III: ##STR00459## in which R.sup.1 denotes H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17 C atoms, or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, in which one or more CH.sub.2-groups may be replaced by ##STR00460## n is 0, 1 or 2, ##STR00461## on each occurrence, independently of one another, denote ##STR00462## in which R.sup.L, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, or ##STR00463## in which one or more H atoms may be replaced by a group R.sup.L or F, and wherein ##STR00464## alternatively denotes ##STR00465## R.sup.2 denotes H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17 C atoms, or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, in which one or more CH.sub.2-groups may be replaced by ##STR00466## Z.sup.21 denotes trans-CHCH, trans-CFCF or CC, and ##STR00467## independently of one another, denote ##STR00468## in which R.sup.L, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, or ##STR00469## in which one or more H atoms may be replaced by a group R.sup.L or F, R.sup.3 denotes H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17 C atoms, or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, in which one or more CH.sub.2-groups may be replaced by ##STR00470## one of Z.sup.31 and Z.sup.32 denotes trans-CHCH, trans-CFCF or CC and the other one, independently thereof, denotes CC, trans-CHCH, trans-CFCF or a single bond, and ##STR00471## independently of one another, denote ##STR00472## in which R.sup.L, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, or ##STR00473## in which one or more H atoms may be replaced by a group R.sup.L or F, and wherein ##STR00474## alternatively denotes ##STR00475##

2. The medium according to claim 1, wherein the medium comprises one or more compounds of formula C selected from the group consisting of the compounds of the formulae C-1, C-2 and CL-1 and CL-2 ##STR00476## in which the occurring groups have the meanings given for formula C.

3. The liquid crystal medium according to claim 1, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae I-1 to I-5 ##STR00477## in which L.sup.1, L.sup.2 and L.sup.3 on each occurrence, identically or differently, denote H or F, and R.sup.1, ##STR00478## have the meanings given for formula I.

4. The liquid crystal medium according to claim 1, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae II-1 to II-3 ##STR00479## in which R.sup.2, ##STR00480## have the meanings given for formula II.

5. The medium according to claim 1, wherein the medium comprises one or more compounds of formula III selected from the group consisting of the compounds of the formulae III-1 to III-6 ##STR00481## in which Z.sup.31 and Z.sup.32 independently of one another denote trans-CHCH or trans-CFCF, preferably trans-CHCH, and in formula III-6 alternatively one of Z.sup.31 and Z.sup.32 may denote CC and the other groups have the meaning given under formula III, R.sup.3 denotes unfluorinated alkyl or alkoxy having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms, and one of ##STR00482## denotes ##STR00483## and the others, independently of one another, denote ##STR00484## where ##STR00485## alternatively denotes ##STR00486##

6. The medium according to claim 1, wherein the medium comprises one or more compounds of formula T ##STR00487## in which R.sup.T denotes halogen, CN, NCS, R.sup.F, R.sup.FO or R.sup.FS, wherein R.sup.F denotes fluorinated alkyl or fluorinated alkenyl having up to 12 C atoms, ##STR00488## on each occurrence, independently of one another, denote ##STR00489## L.sup.4 and L.sup.5 identically or differently, denote F, Cl or straight-chain or branched or cyclic alkyl or alkenyl each having up to 12 C atoms; Z.sup.T3, Z.sup.T4 identically or differently, denote CHCH, CFCF, CHCF, CFCH, CC or a single bond, and t is 0 or 1.

7. The medium according to claim 1, wherein the medium comprises one or more compounds of formula U ##STR00490## in which R.sup.U denotes H, alkyl or alkoxy having 1 to 12 C atoms, or alkenyl, alkenyloxy or alkoxyalkyl having 2 to 12 C atoms, in which one or more CH.sub.2-groups may be replaced by ##STR00491## or denotes a group R.sup.P, R.sup.P denotes halogen, CN, NCS, R.sup.F, R.sup.PO or R.sup.PS, wherein R.sup.P denotes fluorinated alkyl or fluorinated alkenyl having up to 9 C atoms, Z.sup.U1, Z.sup.U2 identically or differently, denote CHCH, CFCF, CHCF, CFCH, CC or a single bond, X.sup.1, X.sup.2, X.sup.3 and X.sup.4 identically or differently, denote Cl or F, t is 0 or 1, and ##STR00492## denote a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6-naphthylene, in which one or two CH groups may be replaced by N and in which one or more H atoms may be replaced by L, wherein tetrafluoro-1,4-phenylene is excluded, b) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, bicyclo[1.1.1]pentane-1,3-diyl, 4,4-bicyclohexylene, bicyclo[2.2.2]octane-1,4-diyl and spiro[3.3]heptane-2,6-diyl, in which one or more non-adjacent CH.sub.2 groups may be replaced by O and/or S and in which one or more H atoms may be replaced by F, and c) the group consisting of thiophene-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl, selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, wherein L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5 or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms.

8. The medium according to claim 1, wherein the medium comprises one or more compounds selected from the group consisting of the compounds of the formulae U-1 to U-11 ##STR00493## ##STR00494## in which L.sup.1, L.sup.2 and L.sup.3 identically or differently, denote H, F, Cl, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl, R.sup.U denotes H, alkyl or alkoxy having 1 to 12 C atoms, or alkenyl, alkenyloxy or alkoxyalkyl having 2 to 12 C atoms, in which one or more CH.sub.2 ##STR00495## groups may be replaced by or denotes a group R.sup.P, R.sup.P denotes halogen, CN, NCS, R.sup.F, R.sup.PO or R.sup.PS, wherein R.sup.P denotes fluorinated alkyl or fluorinated alkenyl having up to 9 C atoms, and X.sup.1, X.sup.2, X.sup.3 and X.sup.4 identically or differently, denote Cl or F.

9. A compound of formula C as defined in claim 1, in which at least one of X.sup.1 and X.sup.2 is different from H.

10. A compound of formula CL ##STR00496## in which R.sup.C1 denotes H, straight-chain or branched alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms, in which one or more CH.sub.2-groups may be replaced by ##STR00497## where one or more non-adjacent CH.sub.2-groups may be replaced by O and where one or more H atoms may be replaced by F, Z.sup.C2 denotes CHCH, CFCF, CHCF, CFCH or CC, X.sup.1, X.sup.2 identically or differently, denote H, Cl, F or methyl, Y denotes H, Cl, F, or alkyl or alkoxy each having 1 to 6 C atoms, ##STR00498## denotes ##STR00499## R.sup.C2 denotes H, CH.sub.3 or F, and t is 0 or 1.

11. The compound according to claim 10, wherein the group Z.sup.C2 denotes CC.

12. The compound according to claim 10, wherein t is 1 and the group ##STR00500## denotes ##STR00501##

13. The compound according to claim 10, wherein the group R.sup.C2 denotes CH.sub.3.

14. A component for high-frequency technology, characterised in that it comprises the liquid crystal medium according to claim 1.

15. The component according to claim 14, wherein the component is a liquid-crystal based antenna element, a phase shifter, a tunable filter, a tunable metamaterial structure, a matching network or a varactor.

16. A microwave antenna array, characterised in that it comprises one or more components according to claim 14.

Description

EXAMPLES

[0720] The following examples illustrate the present invention without limiting it in any way. It is clear to the person skilled in the art from the physical properties what properties can be achieved and in what ranges they can be modified. In particular, the combination of the various properties which can preferably be achieved is thus well defined for the person skilled in the art.

SYNTHESIS EXAMPLES

Abbreviations

[0721] RT room temperature (typically 20 C.1 C.) [0722] THF Tetrahydrofuran [0723] MTB ether Methyl-tert-butyl ether [0724] DCM Dichloromethane [0725] dist. distilled [0726] XPhos 2-Dicyclohexylphosphino-2,4,6-triisopropylbiphenyl [0727] XPhos Pd G2 Chloro(2-dicyclohexylphosphino-2,4,6-triisopropyl-1,1-biphenyl)[2-(2-amino-1,1-biphenyl)palladium (II)

Step 1: 1-(2,2-Dibromovinyl)-4-(4-propylcyclohexyl)cyclohexane

[0728] ##STR00400##

[0729] A solution of carbon tetrabromide (14.0 g, 42 mmol) in dichloromethane (40 ml) is treated with zinc dust (2.8 g, 42 mmol) and triphenylphosphine (11.1 g, 42 mmol), and the reaction mixture is stirred at room temp. overnight. Then a suspension of 4-(4-propylcyclohexyl)cyclohexane carbaldehyde (5.0 g, 21 mmol) in dichloromethane (60 ml) is added dropwise, and the reaction mixture is stirred at room temperature for 2 h. It is filtered and concentrated in vacuo, and the residue is dissolved in a mixture of heptane, methanol and dist. water. The phases are separated, and the aqueous phase is extracted with heptane. The combined organic phases are washed with methanol/water, dried (sodium sulfate) and concentrated in vacuo. The crude product is purified by flash chromatography (heptane) to give 1-(2,2-dibromovinyl)-4-(4-propylcyclohexyl)cyclohexane as a colorless oil.

Step 2: 1-Ethynyl-4-(4-propylcyclohexyl)cyclohexane

[0730] ##STR00401##

[0731] A solution of n-butyllithium in hexane (9.8 ml, 15.5 mmol) is added slowly to a solution of 1-(2,2-dibromovinyl)-4-(4-propylcyclohexyl)cyclohexane (2.9 g, 7.4 mmol) in tetrahydrofuran (15 ml) at 70 C. The reaction mixture is stirred for 1 h at 70 C. and then allowed to warm up to room temp. and stirred for an additional hour. It is hydrolyzed with water at 0 C., and the phases are separated. The aqueous phase is extracted with methyl tert-butyl ether. The combined organic phases are washed with brine, dried (sodium sulfate) and concentrated in vacuo. The residue is purified by flash chromatography (heptane) to give 1-ethynyl-4-(4-propylcyclohexyl)cyclohexane as a light yellow oil.

Step 3: 2,6-Difluoro-4-[2-[4-(4-propylcyclohexyl)cyclohexyl]ethynyl]aniline

[0732] ##STR00402##

[0733] A solution of 1-ethynyl-4-(4-propylcyclohexyl)cyclohexane (1.5 g, 6.5 mmol) and 4-bromo-2,6-difluoro-aniline (1.3 g, 6.1 mmol) in diisopropylamine (15 ml) and tetrahydrofuran (15 ml) is heated to 70 C. under nitrogen. Then XPhos Pd G2 (10 mg, 0.01 mmol), XPhos (6 mg, 0.01 mmol) and copper(I)-iodide (1 mg, 0.01 mmol) are added, and the reaction mixture is stirred at 70 C. overnight. Then it is filtered and concentrated in vacuo. The residue is purified by flash chromatography (heptane/methyl tert-butyl ether) to give 2,6-difluoro-4-[2-[4-(4-propylcyclohexyl)cyclohexyl]ethynyl]aniline as a light brown solid.

Step 4

1,3-Difluoro-2-isothiocyanato-5-[2-[4-(4-propylcyclohexyl)cyclohexyl]ethynyl]benzene

[0734] ##STR00403##

[0735] Thiophosgene (0.4 mL, 5.2 mmol) is added dropwise to a mixture of 2,6-difluoro-4-[2-[4-(4-propylcyclohexyl)cyclohexyl]ethynyl]aniline (1.7 g, 4.7 mmol) and 1,4-diazabicyclo[2.2.2]octane (1.3 g, 11.8 mmol) in dichloromethane (20 ml) at 0 C., and the reaction mixture is stirred for 1 h at room temperature. It is hydrolyzed with brine, and the phases are separated. The aqueous phase is washed with dichloromethane, and the combined organic phases are dried (sodium sulfate) and concentrated in vacuo. The residue is purified by flash chromatography (heptane) and crystallization with heptane to give 1,3-difluoro-2-isothiocyanato-5-[2-[4-(4-propylcyclohexyl)cyclohexyl]ethynyl]benzene as pale yellow crystals.

[0736] Phase sequence: K 69 N 224 I. [0737] =14.8 [0738] n=0.2617

[0739] In analogy to Synthesis Examples 1 to 4 the following compounds are obtained:

TABLE-US-00007 physical No. Compound parameters 1 [00404] K 47 N (9.6) I 2 [00405] 3 [00406] 4 [00407] 5 [00408] 6 [00409] 7 [00410] 8 [00411] 9 [00412] 10 [00413] 11 [00414] 12 [00415] 13 [00416] 14 [00417] 15 [00418] 16 [00419] 17 [00420] 18 [00421] = 17.4 n = 0.327 19 [00422] 20 [00423] 21 [00424] 22 [00425] 23 [00426] 24 [00427] 25 [00428] 26 [00429] 27 [00430] 28 [00431] 29 [00432] 30 [00433] 31 [00434] 32 [00435] 33 [00436] 34 [00437] = 17.7 n = 0.317 35 [00438] 36 [00439] 37 [00440] 38 [00441] 39 [00442] 40 [00443] 41 [00444] 42 [00445] 43 [00446] 44 [00447] 45 [00448] 46 [00449] 47 [00450] 48 [00451]

[0740] The compound according to the invention combines a high clearing temperature with high birefringence which is why it is particularly suitable for microwave applications. The compound of formula CPU-3-F (Table 1) is known for its use in liquid crystalline media for microwave applications from prior art. Due to the aromatic ring P, the clearing temperature is relatively low (198 C.), whereas the corresponding cyclohexane-diyl derivative CCU-3-S has a significantly higher clearing temperature of 225 C. However, the birefringence of the compound CCP-3-S is far too low for the applications according to the invention, where values well above 0.200 are required. Surprisingly, the birefringence of the compound CCU-3-S can be significantly increased to almost the level of CPU-3-S by the introduction of the triple bond while keeping the same high clearing temperature.

TABLE-US-00008 TABLE 1 phase sequence n [00452] K 52 N 198 I 0.2950 CPU-3-F [00453] K 65 N 225 I 0.1990 CCU-3-F [00454] K 69 N 224 I 0.2617 CCTU-3-F

Mixture Examples

[0741] Liquid-crystal mixtures C1 and N1 having the compositions and properties as indicated in the following tables are prepared and characterized with respect to their general physical properties and their applicability in microwave components at 19 GHz and

Comparative Example C1

[0742]

TABLE-US-00009 CPG-3-F 12.0% T(N,I) [ C.]: 92.5 CPG-5-F 10.0% n [589 nm, 20 C.]: 0.0969 CCEP-3-OT 5.0% n.sub.e [589 nm, 20 C.]: 1.5764 CCEP-5-OT 5.0% n.sub.o [589 nm, 20 C.]: 1.4795 CGPC-3-3 2.0% [1 kHz, 20 C.]: 5.3 CGPC-5-3 2.0% .sub. [1 kHz, 20 C.]: 8.4 CGPC-5-5 2.0% .sub. [1 kHz, 20 C.]: 3.1 CP-6-F 8.0% .sub.1 [mPa s, 20 C.]: 128 CP-7-F 6.0% K.sub.1 [pN, 20 C.]: 13.2 CCP-2-OT 8.0% K.sub.3 [pN, 20 C.]: 19.6 CCP-3-OT 12.0% K.sub.3/K.sub.1 [pN, 20 C.]: 1.48 CCP-4-OT 7.0% V.sub.0 [V, 20 C.]: 1.66 CCP-5-OT 11.0% [20 C., 19 GHz]: 0.100 CP-5-F 10.0% .sub.r, [20 C., 19 GHz]: 2.49 100.0% .sub.r, [20 C., 19 GHz]: 2.24 tan .sub. r, [20 C., 19 GHz]: 0.0049 tan .sub. r, [20 C., 19 GHz]: 0.0125 [20 C., 19 GHz]: 8.0

Example N1

[0743]

TABLE-US-00010 C1 90.0% T(N,I) [ C.]: 103 CCTU-3-S 10.0% n [589 nm, 20 C.]: 0.1134 100.0 n.sub.e [589 nm, 20 C.]: 1.5764 n.sub.o [589 nm, 20 C.]: 1.4795 [1 kHz, 20 C.]: 6.3 .sub. [1 kHz, 20 C.]: 9.4 .sub. [1 kHz, 20 C.]: 3.1 [20 C., 19 GHz]: 0.108 .sub.r, [20 C., 19 GHz]: 2.58 .sub.r, [20 C., 19 GHz]: 2.30 tan .sub. r, [20 C., 19 GHz]: 0.0045 tan .sub. r, [20 C., 19 GHz]: 0.0123 [20 C., 19 GHz]: 8.8

[0744] The addition of the compound of formula C to the medium C1 results in a surprisingly higher figure-of-merit which is improved from 8.0 to 8.8 due to higher tunability and reduced dielectric loss tan . Due to its excellent phase properties, the clearing temperature of the medium is also significantly improved from 92.5 to 103 C.