Electro-Optical Display Elements

Abstract

An electro-optical display element in the areas of displays for watches, pocket calculators, large display panels as used in railway stations, airports and sports arenas, displays of portable or desktop computers, navigation systems and video applications, which upon the application of a voltage to the display element achieves that the longitudinal axis of molecules in a liquid-crystalline media orients itself in such a way that the larger of the dielectric constants becomes effective, which electro-optical display element contains two plates of a capacitor.

Claims

1. An electro-optical display element in the areas of displays for watches, pocket calculators, large display panels as used in railway stations, airports and sports arenas, displays of portable or desktop computers, navigation systems and video applications, which upon the application of a voltage to the display element achieves that the longitudinal axis of molecules in a liquid-crystalline media orients itself in such a way that the larger of the dielectric constants becomes effective.

2. An electro-optical display element according to claim 1, which comprises two plates of a capacitor.

3. An electro-optical display element according to claim 1, wherein the dielectric constant ε.sub.∥ parallel to the longitudinal axes of molecules is larger than the dielectric constant ε.sub.⊥ perpendicular to the longitudinal axes of the molecules, whereby the dielectric anisotropy Δε is negative.

4. An electro-optical display element according to claim 1, wherein the molecules have a dielectric anisotropy Δε that is negative, and in the field-free state, these molecules are oriented with their longitudinal axis perpendicular to the glass surface of the display, wherein the application of an electric field causes them to orient themselves more or less parallel to the glass surfaces.

5. An electro-optical display element according to claim 1, which is a VA-TFT display, wherein the molecules have a negative Δε, and preferably have a Δε≤−4 and particularly preferably a Δε≤−8, and they exhibit good miscibility with the conventional substances used in liquid-crystal mixtures for displays, and have advantageously low rotational viscosities, among also other physical, physicochemical or electro-optical parameters of the compounds being also advantageous for use of the compounds in liquid-crystalline media, which have, in particular, an adequate width of the nematic phase and good low-temperature and long-term stability as well as sufficiently high clearing points, among also low melting points, which give an indication of the advantageous mixing behaviour, and furthermore, the molecules have values of the optical anisotropy Δn which are of greater than 0.15 and less than 0.25.

6. An electro-optical display element according to claim 1, wherein the molecules are of formula I ##STR00026## in which m and n are each, independently of one another, 0 or 1, and R.sup.1 and R.sup.2, independently of one another, denote an alkyl radical having 1 to 15 C atoms or an alkenyl or alkynyl radical having 2 to 15 C atoms, each of which are optionally mono- or polyhalogenated.

7. An electro-optical display element according to claim 1, wherein the molecules are of formula I ##STR00027## in which m and n both denote 1 and R.sup.1 and R.sup.2 each, independently of one another, denotes an alkyl radical having 2 to 6 carbon atoms or an alkenyl radical having 3 to 6 carbon atoms.

8. An electro-optical display element according to claim 1, wherein the molecules are of formula I ##STR00028## in which m and n one of m and n is 1 and the other of m and n is 0, and R.sup.1 is methyl, and R.sup.2 is an alkyl radical having 1 to 15 C atoms or an alkenyl or alkynyl radical having 2 to 15 C atoms.

9. An electro-optical display element according to claim 1, wherein the molecules are of formula IA ##STR00029## in which alkyl denotes an alkyl radical having 2 to 6 carbon atoms, and R.sup.2 denotes an alkyl radical having 2 to 6 C atoms or an alkenyl radical having 3 to 6 C atoms.

10. An electro-optical display element according to claim 1, wherein the molecules are one of the following compounds ##STR00030##

11. An electro-optical display element according to claim 1, wherein the molecules are one of the following compounds ##STR00031## wherein TABLE-US-00004 R.sup.1 R.sup.2 —CH.sub.3 —CH.sub.3 —CH.sub.3 —C.sub.2H.sub.5 —CH.sub.3 —C.sub.3H.sub.7 —CH.sub.3 —C.sub.4H.sub.9 —CH.sub.3 —C.sub.5H.sub.11 —CH.sub.3 —C.sub.6H.sub.13 —C.sub.2H.sub.5 —C.sub.2H.sub.5 —C.sub.2H.sub.5 —C.sub.3H.sub.7 —C.sub.2H.sub.5 —C.sub.4H.sub.9 —C.sub.2H.sub.5 —CH.sub.2CH(CH.sub.3).sub.2 —C.sub.2H.sub.5 —(CH.sub.2).sub.2CH═CH.sub.2 —C.sub.2H.sub.5 —(CH.sub.2).sub.2CH(CH.sub.3).sub.2 —C.sub.2H.sub.5 —C.sub.5H.sub.11 —C.sub.2H.sub.5 —C.sub.6H.sub.13 —C.sub.2H.sub.5 —(CH.sub.2).sub.3CH(CH.sub.3).sub.2 —C.sub.3H.sub.7 —C.sub.3H.sub.7 —C.sub.3H.sub.7 —C.sub.4H.sub.9 —C.sub.3H.sub.7 —C.sub.5H.sub.11 —C.sub.3H.sub.7 —C.sub.6H.sub.13 —C.sub.4H.sub.9 —C.sub.4H.sub.9 —C.sub.4H.sub.9 —C.sub.5H.sub.11 —C.sub.4H.sub.9 —(CH.sub.2).sub.2CH═CHCH.sub.3*.sup.) —C.sub.4H.sub.9 —C.sub.6H.sub.13 —C.sub.5H.sub.11 —C.sub.5H.sub.11 —C.sub.5H.sub.11 —C.sub.6H.sub.13 wherein R.sup.1 and R.sup.2 are straight-chain unless indicated otherwise and .sup.*) indicates a trans isomer.

12. An electro-optical display element according to claim 1, wherein the molecules are one of the following compounds ##STR00032## wherein TABLE-US-00005 R.sup.1 R.sup.2 —CH.sub.3 —C.sub.3H.sub.7 —CH.sub.3 —C.sub.4H.sub.9 —CH.sub.3 —C.sub.5H.sub.11 —C.sub.2H.sub.5 —C.sub.3H.sub.7 —C.sub.2H.sub.5 —C.sub.4H.sub.9 —C.sub.2H.sub.5 —CH.sub.2CH(CH.sub.3).sub.2 —C.sub.2H.sub.5 —(CH.sub.2).sub.2CH═CH.sub.2 —C.sub.2H.sub.5 —(CH.sub.2).sub.2CH(CH.sub.3).sub.2 —C.sub.2H.sub.5 —C.sub.5H.sub.11 —C.sub.2H.sub.5 —C.sub.6H.sub.13 —C.sub.2H.sub.5 —(CH.sub.2).sub.3CH(CH.sub.3).sub.2 —C.sub.3H.sub.7 —C.sub.3H.sub.7 —C.sub.3H.sub.7 —C.sub.4H.sub.9 —C.sub.3H.sub.7 —C.sub.5H.sub.11 —C.sub.3H.sub.7 —C.sub.6H.sub.13 —C.sub.4H.sub.9 —C.sub.4H.sub.9 —C.sub.4H.sub.9 —C.sub.5H.sub.11 —C.sub.4H.sub.9 —(CH.sub.2).sub.2CH═CHCH.sub.3*.sup.) wherein R.sup.1 and R.sup.2 are straight-chain unless indicated otherwise and .sup.*) indicates a trans isomer.

13. An electro-optical display element according to claim 1, wherein the molecules are ##STR00033##

14. An electro-optical display element according to claim 7, wherein R.sup.1 and R.sup.2 each, independently of one another, denotes an alkyl radical having 2 to 6 carbon atoms.

15. An electro-optical display element according to claim 7, wherein the sum of the number of carbon atoms in R.sup.1 and R.sup.2 is 4, 5, 6, 7, 8, 9 or 10.

16. An electro-optical display element according to claim 1, wherein the molecules are of formula IB ##STR00034## in which alkyl is methyl, and R.sup.2 is an alkyl radical having 1 to 15 C atoms or an alkenyl or alkynyl radical having 2 to 15 C atoms.

17. An electro-optical display element according to claim 1, wherein the molecules are one of the following compounds TABLE-US-00006 R.sup.1 R.sup.2 —CH.sub.3 —CH.sub.3. —CH.sub.3 —C.sub.2H.sub.5 —CH.sub.3 —C.sub.3H.sub.7 —CH.sub.3 —C.sub.4H.sub.9 —CH.sub.3 —C.sub.5H.sub.11 —CH.sub.3 —C.sub.6H.sub.13.

18. An electro-optical display element according to claim 6, wherein the sum m+n is 1 or 2, and/or R.sup.1 and R.sup.2, independently of one another, denote an alkyl radical having 1 to 7 carbon atoms or an alkenyl radical having 2 to 7 carbon atoms, and/or the sum of the number of carbon atoms in R.sup.1 and R.sup.2 is 4, 5, 6, 7, 8, 9 or 10.

19. An electro-optical display element according to claim 6, wherein m and n both denote 1.

20. An electro-optical display element containing a liquid-crystalline medium comprising at least two compounds, one of which is a compound of formula I ##STR00036## in which m and n are each, independently of one another, 0 or 1, and R.sup.1 and R.sup.2, independently of one another, denote an alkyl radical having 1 to 15 C atoms or an alkenyl or alkynyl radical having 2 to 15 C atoms, each of which are optionally mono- or polyhalogenated.

Description

EXAMPLES

[0092] The starting substances can be obtained in accordance with generally accessible literature procedures or commercially.

Example 1: 3-Butoxy-4,6-difluoro-7-propoxydibenzofuran

[0093] ##STR00014##

[0094] Step 1

##STR00015##

[0095] 50 g of dibenzofuran are initially introduced in 1500 ml of THF, and 152 g of 15% BuLi soln. in hexane are added dropwise at −60 to −75° C. The mixture is warmed to RT and stirred for a further 3 h. The mixture is then recooled to −75° C., and a solution of 112.5 g of N-fluorobenzenesulfonimide in 1000 ml of THF is added at −75 to −60° C. After a further 30 min at −70° C., the reaction mixture is allowed to warm to ambient temperature, and the batch is hydrolysed using water and subjected to extractive work-up. The crude product (red-brown oil) is purified by chromatography (eluent: n-heptane).

[0096] White crystals.

[0097] Step 2

##STR00016##

[0098] 40 g of 4-fluorodibenzofuran are initially introduced in 450 ml of THF, and 96 g of 15% BuLi soln. in hexane are added dropwise at −60 to −75° C. The mixture is stirred for a further 2 hours. A solution of 25 g of trimethyl borate in 80 ml of THF is then added at −75 to −60° C. After a further 30 min at −70° C., the reaction mixture is allowed to warm to ambient temperature, and the batch is slowly hydrolysed using a mixture of 30 g of glacial acetic acid and 40 ml of water. 40 g of 30% hydrogen peroxide are subsequently added dropwise at such a rate that the temperature does not exceed 45° C. The mixture is stirred at RT for a further 12 h and subjected to extractive work-up.

[0099] The crude product is purified by chromatography (eluent: n-heptane/MTB 4/1).

[0100] White crystals.

[0101] Step 3

##STR00017##

[0102] 36.8 g of 4-fluorodibenzofuran-3-ol, 13.6 g of imidazole and 24.5 g of DMAP are dissolved in 700 ml of DMF, and a solution of 55 g of chloro-triisopropylsilane in 35 ml of DMF is added at 25° C. The mixture is stirred at RT for a further 12 h, and the batch is carefully poured into ice-water and subjected to extractive work-up.

[0103] The crude product is purified by chromatography (eluent: n-heptane/chlorobutane 9/1).

[0104] Colourless oil.

[0105] Step 4

##STR00018##

[0106] 30.8 g of (4-fluorodibenzofuran-3-yloxy)triisopropylsilane are initially introduced in 850 ml of THF, and 106 g (3 eq.) of 15% BuLi soln. in hexane are added dropwise at −60 to −75° C. The mixture is warmed to −40° C. and stirred at this temperature for a further 5 h. The mixture is then re-cooled to −65° C., and a solution of 78.8 g of N-fluorobenzenesulfonimide in 300 ml of THF is added at −65 to −50° C. After a further 30 min at −50° C., the reaction mixture is allowed to warm to ambient temperature, and the batch is hydrolysed using water and subjected to extractive work-up.

[0107] The crude product (red-brown oil) is purified by chromatography (eluent: n-heptane/chlorobutane 4/1) and recrystallised from ethanol.

[0108] White crystals.

[0109] Step 5

##STR00019##

[0110] 15.4 g of (4,6-difluorodibenzofuran-3-yloxy)triisopropylsilane are dissolved in 150 ml of THF, and 57 ml of a 1 M solution of tetrabutylammonium fluoride in THF are added at 5° C. The mixture is stirred at RT for a further 30 min and subjected to extractive work-up.

[0111] The crude product is purified by chromatography (eluent: n-heptane/MTB 2/1) and recrystallised from heptane/toluene 1/1.5.

[0112] White crystals.

[0113] Step 6

##STR00020##

[0114] 17.3 g of 4,6-difluorodibenzofuran-3-ol are boiled under reflux with 14.5 g of n-propyl bromide and 16.3 g of potassium carbonate in 150 ml of methyl ethyl ketone for 15 h. The mixture is subjected to extractive work-up.

[0115] The crude product is purified by chromatography (eluent: n-heptane/MTB 4/1) and recrystallised from heptane.

[0116] White crystals.

[0117] Step 7

##STR00021##

[0118] 17.3 g of 4,6-difluoro-3-propyloxydibenzofuran are initially introduced in 250 ml of THF, and 33 g of 15% BuLi soln. in hexane are added dropwise at −60 to −75° C. The mixture is stirred for a further 2 h. A solution of 7.9 g of trimethyl borate in 20 ml of THF is then added at −75 to −60° C. After a further 30 min at −70° C., the reaction mixture is allowed to warm to RT, and the batch is slowly hydrolysed using a mixture of 10 g of glacial acetic acid and 12 ml of water. 16 g of 30% hydrogen peroxide are subsequently added dropwise at such a rate that the temperature does not exceed 45° C. The mixture is stirred at RT for a further 12 h and subjected to extractive work-up.

[0119] The crude product is purified by chromatography (eluent: n-heptane/MTB 3/1).

[0120] Yield 9.9 g. White crystals.

[0121] Step 8

##STR00022##

[0122] 7.1 g of 4,6-difluoro-7-propoxydibenzofuran-3-ol are boiled under reflux with 7 g of n-butyl bromide and 5.3 g of potassium carbonate in 65 ml of methyl ethyl ketone for 5 h. The mixture is subjected to extractive work-up. The crude product is purified by chromatography (eluent: n-heptane/chlorobutane 2/1) and recrystallised from heptane.

[0123] Yield 7.9 g. White crystals.

[0124] Phases: C 68 I (m.p. 68° C., cf. also table).

[0125] The following compounds are prepared analogously to Example 1:

##STR00023##

[0126] The radicals R.sup.1/2 are straight-chain, i.e. unbranched, unless indicated otherwise. The substance data are given in Table 1.

TABLE-US-00001 TABLE 1 M.p. γ.sub.1 Cl. p. R.sup.1 R.sup.2 [° C.] Δε Δn [mPa .Math. s] [° C.] —CH.sub.3 —CH.sub.3 —CH.sub.3 —C.sub.2H.sub.5 119 —CH.sub.3 —C.sub.3H.sub.7 93 −15 0.193 149 59 —CH.sub.3 —C.sub.4H.sub.9 79 −13 0.191 144 60 —CH.sub.3 —C.sub.5H.sub.11 79 −14 0.185 144 46 —CH.sub.3 —C.sub.6H.sub.13 —C.sub.2H.sub.5 —C.sub.2H.sub.5 —C.sub.2H.sub.5 —C.sub.3H.sub.7 85 −15 0.189 128 66 —C.sub.2H.sub.5 —C.sub.4H.sub.9 77 −14 0.189 116 62 —C.sub.2H.sub.5 —CH.sub.2CH(CH.sub.3).sub.2 90 −14 0.183 152 55 —C.sub.2H.sub.5 —(CH.sub.2).sub.2CH═CH.sub.2 87 −14 0.196 102 51 —C.sub.2H.sub.5 —(CH.sub.2).sub.2CH(CH.sub.3).sub.2 90 −14 0.179 108 41 —C.sub.2H.sub.5 —C.sub.5H.sub.11 57 −14 0.181 119 59 —C.sub.2H.sub.5 —C.sub.6H.sub.13 68 −13 0.180 131 61 —C.sub.2H.sub.5 —(CH.sub.2).sub.3CH(CH.sub.3).sub.2 56 −13 0.167 144 51 —C.sub.3H.sub.7 —C.sub.3H.sub.7 75 −14 0.193 123 68 —C.sub.3H.sub.7 —C.sub.4H.sub.9 68 −13 0.192 115 63 —C.sub.3H.sub.7 —C.sub.5H.sub.11 63 −13 0.176 104 58 —C.sub.3H.sub.7 —C.sub.6H.sub.13 69 −13 0.171 125 61 —C.sub.4H.sub.9 —C.sub.4H.sub.9 87 −12 0.184 73 62 —C.sub.4H.sub.9 —C.sub.5H.sub.11 76 −12 0.181 111 59 —C.sub.4H.sub.9 —(CH.sub.2).sub.2CH═CHCH.sub.3*.sup.) 65 −13 0.187 116 36 —C.sub.4H.sub.9 —C.sub.6H.sub.13 —C.sub.5H.sub.11 —CF.sub.3 64 −4 0.132 73 −24 —C.sub.5H.sub.11 —C.sub.5H.sub.11 —C.sub.5H.sub.11 —C.sub.6H.sub.13 *.sup.)trans isomer

[0127] The following compounds are prepared analogously to Example 1 and Scheme 2:

##STR00024##

[0128] The radicals R.sup.1/2 are straight-chain, i.e. unbranched, unless indicated otherwise. The substance data are given in Table 2.

TABLE-US-00002 TABLE 2 M.p. γ.sub.1 Cl. p. R.sup.1 R.sup.2 [° C.] Δε Δn [mPa .Math. s] [° C.] —CH.sub.3 —CH.sub.3 —CH.sub.3 —C.sub.2H.sub.5 100 −10 0.197 75 45 —CH.sub.3 —C.sub.3H.sub.7 102 −10 0.187 90 39 —CH.sub.3 —C.sub.4H.sub.9 82 −9 0.183 84 35 —CH.sub.3 —C.sub.5H.sub.11 74 −9 0.172 89 28 —CH.sub.3 —C.sub.6H.sub.13 61 −9 0.170 98 26 —C.sub.2H.sub.5 —CH.sub.3 —C.sub.2H.sub.5 —C.sub.2H.sub.5 60 −9 0.182 65 16 —C.sub.2H.sub.5 —C.sub.3H.sub.7 —C.sub.2H.sub.5 —C.sub.4H.sub.9 —C.sub.2H.sub.5 —CH.sub.2CH(CH.sub.3).sub.2 —C.sub.2H.sub.5 —(CH.sub.2).sub.2CH═CH.sub.2 —C.sub.2H.sub.5 —(CH.sub.2).sub.2CH(CH.sub.3).sub.2 —C.sub.2H.sub.5 —C.sub.5H.sub.11 —C.sub.2H.sub.5 —C.sub.6H.sub.13 —C.sub.2H.sub.5 —(CH.sub.2).sub.3CH(CH.sub.3).sub.2 —C.sub.3H.sub.7 —CH.sub.3 —C.sub.3H.sub.7 —C.sub.2H.sub.5 63 −10 0.177 74 9 —C.sub.3H.sub.7 —C.sub.3H.sub.7 54 −8 0.174 72 7 —C.sub.3H.sub.7 —C.sub.4H.sub.9 65 −8 0.167 67 8 —C.sub.3H.sub.7 —(CH.sub.2).sub.2CH═CH.sub.2 50 −8 0.171 55 −6 —C.sub.3H.sub.7 —C.sub.5H.sub.11 —C.sub.3H.sub.7 —C.sub.6H.sub.13 —C.sub.4H.sub.9 —CH.sub.3 —C.sub.4H.sub.9 —C.sub.2H.sub.5 56 −9 0.172 83 5 —C.sub.4H.sub.9 —C.sub.3H.sub.7 —(CH.sub.2).sub.2—CH═CH.sub.2 —C.sub.2H.sub.5 68 −9 0.188 79 17 —C.sub.4H.sub.9 —C.sub.4H.sub.9 —C.sub.4H.sub.9 —C.sub.5H.sub.11 —C.sub.4H.sub.9 —(CH.sub.2).sub.2CH═CHCH.sub.3*.sup.) —C.sub.4H.sub.9 —C.sub.6H.sub.13 —C.sub.5H.sub.11 —CH.sub.3 —C.sub.5H.sub.11 —C.sub.2H.sub.5 60 −9 0.177 88 13 —(CH.sub.2).sub.2—CH═CH—CH.sub.3*.sup.) —C.sub.2H.sub.5 90 −10 0.193 94 49 —C.sub.5H.sub.11 —C.sub.3H.sub.7 —C.sub.5H.sub.11 —C.sub.4H.sub.9 64 −8 0.162 73 11 —C.sub.5H.sub.11 —(CH.sub.2).sub.2CH═CH.sub.2 70 −8 0.165 71 −2 —C.sub.5H.sub.11 —C.sub.6H.sub.13 *.sup.)trans isomer

[0129] The following compounds are prepared analogously to Example 1 and Scheme 3:

##STR00025##

[0130] The radicals R.sup.1/2 are straight-chain, i.e. unbranched, unless indicated otherwise. The substance data are given in Table 3.

TABLE-US-00003 TABLE 3 M.p. γ.sub.1 Cl. p. R.sup.1 R.sup.2 [° C.] Δε Δn [mPa .Math. s] [° C.] —CH.sub.3 —CH.sub.3 —CH.sub.3 —C.sub.2H.sub.5 —CH.sub.3 —C.sub.3H.sub.7 —CH.sub.3 —C.sub.4H.sub.9 —CH.sub.3 —C.sub.5H.sub.11 63 −5 0.151 59 −20 —CH.sub.3 —C.sub.6H.sub.13 —CH.sub.3 —(CH.sub.2).sub.2CH═CH.sub.2 51 −4 0.157 108 −12 —CH.sub.3 —(CH.sub.2).sub.2CH═CHCH.sub.3*.sup.) 59 −5 0.181 100 10 —C.sub.2H.sub.5 —C.sub.2H.sub.5 —C.sub.2H.sub.5 —C.sub.3H.sub.7 42 −4 0.142 33 −57 —C.sub.2H.sub.5 —C.sub.4H.sub.9 —C.sub.2H.sub.5 —CH.sub.2CH(CH.sub.3).sub.2 —C.sub.2H.sub.5 —(CH.sub.2).sub.2CH═CH.sub.2 —C.sub.2H.sub.5 —(CH.sub.2).sub.2CH(CH.sub.3).sub.2 —C.sub.2H.sub.5 —C.sub.5H.sub.11 —C.sub.2H.sub.5 —C.sub.6H.sub.13 —C.sub.2H.sub.5 —(CH.sub.2).sub.3CH(CH.sub.3).sub.2 —C.sub.3H.sub.7 —C.sub.3H.sub.7 —C.sub.3H.sub.7 —C.sub.4H.sub.9 —C.sub.3H.sub.7 —(CH.sub.2).sub.2CH═CH.sub.2 50 −4 0.151 44 −49 —C.sub.3H.sub.7 —C.sub.5H.sub.11 —C.sub.3H.sub.7 —C.sub.6H.sub.13 —C.sub.4H.sub.9 —C.sub.4H.sub.9 38 −5 0.131 44 −63 —(CH.sub.2).sub.2—CH═CH.sub.2 —(CH.sub.2).sub.2CH═CH.sub.2 60 −5 0.159 51 −36 —C.sub.4H.sub.9 —C.sub.5H.sub.11 —C.sub.4H.sub.9 —(CH.sub.2).sub.2CH═CHCH.sub.3*.sup.) —C.sub.4H.sub.9 —C.sub.6H.sub.13 —C.sub.5H.sub.11 —(CH.sub.2).sub.2CH═CH.sub.2 35 −4 0.143 47 −41 —C.sub.5H.sub.11 —C.sub.6H.sub.13 *.sup.)trans isomer

[0131] The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

[0132] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.