DEVICE FOR REGULATING THE PASSAGE OF ENERGY

Abstract

The present application relates to a device for regulating the passage of energy from an outside space into an inside space, to compounds, windows and uses of the devices and compounds.

Claims

1. Device for regulating the passage of energy from an outside space into an inside space, where the device comprises a switching layer, where the switching layer comprises one or more compounds of the formula (I): ##STR00054## where: X is equal to S or Se; Z.sup.1 is, independently of one another, a single bond, —CR.sup.3═CR.sup.3— or —C≡C—; or two, three, four or five groups combined with one another, selected from the groups —CR.sup.3═CR.sup.3— and —C≡C—; Z.sup.2 is, independently of one another, a single bond, O, S, C(R.sup.3).sub.2, —CR.sup.3═CR.sup.3— or —C≡C—; or two, three, four or five groups combined with one another, selected from the groups O, S, C(R.sup.3).sub.2, —CR.sup.3═CR.sup.3— and —C≡C—; Ar.sup.1 is, independently of one another, an aryl or heteroaryl group having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R.sup.4; R.sup.1 is, independently of one another, H, D, F, CN, N(R.sup.5).sub.2, or an alkyl, alkoxy or thioalkoxy group having 1 to 20 C atoms, which may be substituted by one or more radicals R.sup.5, where one or more CH.sub.2 groups in the alkyl, alkoxy or thioalkoxy groups may be replaced by —R.sup.5C═CR.sup.5—, —C≡C—, C═O, C═S, —C(═O)O—, —OC(═O)—, Si(R.sup.5).sub.2, NR.sup.5, —O— or —S—; R.sup.3, R.sup.4 are, independently of one another, H, D, F, Cl, CN, or an alkyl, alkoxy or thioalkoxy group having 1 to 10 C atoms, which may be substituted by one or more radicals R.sup.5, where one or more CH.sub.2 groups in the alkyl, alkoxy or thioalkoxy groups may be replaced by —R.sup.5C═CR.sup.5—, —C≡C—, C═O, C═S, —C(═O)O—, —OC(═O)—, Si(R.sup.5).sub.2, NR.sup.5, —O— or —S—; R.sup.5 is, independently of one another, H, D, F, Cl, CN, N(R.sup.6).sub.2, an alkyl, alkoxy or thioalkoxy group having 1 to 10 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms, where the above-mentioned groups may each be substituted by one or more radicals R.sup.6 and where one or more CH.sub.2 groups in the above-mentioned groups may be replaced by —R.sup.6C═CR.sup.6—, —C≡C—, C═O, C═S, —C(═O)O—, —O(C═O)—, Si(R.sup.6).sub.2, NR.sup.6, —O— or —S—, or an aryl or heteroaryl group having 5 to 30 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.6; R.sup.6 is, independently of one another, H, F or an aliphatic organic radical having 1 to 20 C atoms, in which one or more H atoms may be replaced by F, or an aryl or heteroaryl group having 5 to 20 C atoms, in which one or more H atoms may be replaced by F; and i is, independently of one another, equal to 0, 1, 2, 3, 4 or 5.

2. Device according to claim 1, characterised in that X is equal to S, and/or in that Z.sup.1 is a single bond.

3. Device according to claim 1, characterised in that Z.sup.2 stands, independently of one another, for a single bond, —C(R.sup.3).sub.2C(R.sup.3).sub.2—, —CR.sup.3═CR.sup.3—, —C≡C—, —OC(R.sup.3).sub.2— or —C(R.sup.3).sub.2O—.

4. Device according to claim 1, characterised in that Ar.sup.1 represents, independently of one another, an aryl group having 6 to 15 C atoms or a heteroaryl group having 5 to 15 C atoms, which may be substituted by one or more radicals R.sup.4.

5. Device according to claim 1, characterised in that Ar.sup.1 is selected on each occurrence from benzene, fluorene, naphthalene, pyridine, pyrimidine, pyrazine, triazine, thiophene, thiophene with condensed-on 1,4-dioxane ring, benzothiophene, dibenzothiophene, benzodithiophene, cyclopentadithiophene, thienothiophene, indenothiophene, dithienopyrrole, silolodithiophene, selenophene, benzoselenophene, dibenzoselenophene, furan, benzofuran, dibenzofuran and quinoline, each of which is optionally substituted by radicals R.sup.4.

6. Device according to claim 1, characterised in that at least one Ar.sup.1 is selected from a sulfur-containing heteroaryl group, which may be substituted by one or more radicals R.sup.4.

7. Device according to claim 1, characterised in that R.sup.1 is selected, independently of one another, from H, F, or a straight-chain alkyl or alkoxy group having 3 to 20 C atoms, which may be substituted by one or more radicals R.sup.5, or a branched alkyl or alkoxy group having 3 to 20 C atoms, which may be substituted by one or more radicals R.sup.5, or a cyclic alkyl group having 6 C atoms, which may be substituted by one or more radicals R.sup.5, where one or more CH.sub.2 groups in the alkyl and alkoxy groups may be replaced by —O—, —S— or —R.sup.5C═CR.sup.5—, or a siloxanyl group having 1 to 6 Si atoms, which may be substituted by one or more radicals R.sup.5.

8. Device according to claim 1, characterised in that the index i is equal to 1 or 2.

9. Device according to claim 1, characterised in that the degree of anisotropy R of the compound of the formula (I), determined as indicated in the working examples, is greater than 0.4.

10. Device according to claim 1, characterised in that, besides the compound of the formula (I), a liquid-crystalline medium comprising one or more different compounds is preferably present in the switching layer.

11. Device according to claim 1, characterised in that it is electrically switchable.

12. Device according to claim 1, characterised in that it is connected to a solar cell or another device for conversion of light and/or heat energy into electrical energy.

13. Window comprising a device according to claim 1.

14. Compound of the formula (I): ##STR00055## where: X is equal to S or Se; Z.sup.1 is, independently of one another, a single bond, —CR.sup.3═CR.sup.3— or —C≡C—; or two, three, four or five groups combined with one another, selected from the groups —CR.sup.3═CR.sup.3— and —C≡C—; Z.sup.2 is, independently of one another, a single bond, O, S, C(R.sup.3).sub.2, —CR.sup.3═CR.sup.3— or —C≡C—; or two, three, four or five groups combined with one another, selected from the groups O, S, C(R.sup.3).sub.2, —CR.sup.3═CR.sup.3— and —C≡C—; Ar.sup.1 is, independently of one another, an aryl or heteroaryl group having 5 to 30 aromatic ring atoms, which may be substituted by one or more radicals R.sup.4; R.sup.1 is, independently of one another, H, D, N(R.sup.7).sub.2, or an alkyl, alkoxy or thioalkoxy group having 1 to 20 C atoms, which may be substituted by one or more radicals R.sup.7, where one or more CH.sub.2 groups in the alkyl, alkoxy or thioalkoxy groups may be replaced by —R.sup.7C═CR.sup.7—, —C≡C—, C═O, C═S, —C(═O)O—, —OC(═O)—, Si(R.sup.7).sub.2, NR.sup.7, —O— or —S—; R.sup.3, R.sup.4 are, independently of one another, H, D, F, Cl, CN, or an alkyl, alkoxy or thioalkoxy group having 1 to 10 C atoms, which may be substituted by one or more radicals R.sup.5, where one or more CH.sub.2 groups in the alkyl, alkoxy or thioalkoxy groups may be replaced by —R.sup.5C═CR.sup.5—, —C≡C—, C═O, C═S, —C(═O)O—, —OC(═O)—, Si(R.sup.5).sub.2, NR.sup.5, —O— or —S—; R.sup.5 is, independently of one another, H, D, F, Cl, CN, N(R.sup.6).sub.2, an alkyl, alkoxy or thioalkoxy group having 1 to 10 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms, where the above-mentioned groups may each be substituted by one or more radicals R.sup.6 and where one or more CH.sub.2 groups in the above-mentioned groups may be replaced by —R.sup.6C═CR.sup.6—, —C≡C—, C═O, C═S, —C(═O)O—, —O(C═O)—, Si(R.sup.6).sub.2, NR.sup.6, —O— or —S—, or an aryl or heteroaryl group having 5 to 30 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.6; R.sup.6 is, independently of one another, H, F or an aliphatic organic radical having 1 to 20 C atoms, in which one or more H atoms may be replaced by F, or an aryl or heteroaryl group having 5 to 20 C atoms, in which one or more H atoms may be replaced by F; R.sup.7 is, independently of one another, H, D, Cl, N(R.sup.8).sub.2, an alkyl, alkoxy or thioalkoxy group having 1 to 10 C atoms or an alkenyl or alkynyl group having 2 to 20 C atoms, where the above-mentioned groups may each be substituted by one or more radicals R.sup.8 and where one or more CH.sub.2 groups in the above-mentioned groups may be replaced by —R.sup.8C═CR.sup.8—, —C≡C—, C═O, C═S, —C(═O)O—, —O(C═O)—, Si(R.sup.8).sub.2, NR.sup.8, —O— or —S—, or an aryl or heteroaryl group having 5 to 30 aromatic ring atoms, which may in each case be substituted by one or more radicals R.sup.8; R.sup.8 is, independently of one another, H or an aliphatic organic radical having 1 to 20 C atoms, or an aryl or heteroaryl group having 5 to 20 C atoms; and i is, independently of one another, equal to 0, 1, 2, 3, 4 or 5, with the proviso that a terminal group Ar.sup.1—Z.sup.2—Ar.sup.1— in a side chain does not consist of terminal unsubstituted thiophene and diethylthiophenyl bonded thereto via a single bond.

15. Electrochemical device comprising a compound according to claim 14.

16. Use of at least one compound according to claim 14 in a window, in organic solar cells, in organic electronic components, in particular semiconductors, for tinting a polymer matrix or as constituent of liquid-crystalline mixtures.

Description

WORKING EXAMPLES

[0182] The following examples are intended to illustrate the present invention and should not be interpreted as restrictive.

[0183] In the present application, structures of liquid-crystalline compounds are reproduced by means of abbreviations (acronyms). These abbreviations are explicitly presented and explained in WO 2012/052100 (pp. 63-89).

[0184] All physical properties are determined in accordance with “Merck Liquid Crystals, Physical Properties of Liquid Crystals”, Status November 1997, Merck KGaA, Germany, and apply for a temperature of 20° C. The value of Δn is determined at 589 nm, and the value of Δ∈ is determined at 1 kHz, unless explicitly indicated otherwise in each case. n.sub.e and n.sub.o are in each case the refractive indices of the extraordinary and ordinary light beam under the conditions indicated above.

[0185] The degree of anisotropy R is determined from the value for the extinction coefficient E(p) (extinction coefficient of the mixture in the case of parallel alignment of the molecules to the polarisation direction of the light) and the value for the extinction coefficient of the mixture E(s) (extinction coefficient of the mixture in the case of perpendicular alignment of the molecules to the polarisation direction of the light), in each case at the wavelength of the maximum of the absorption band of the dye in question. If the dye has a plurality of absorption bands, the strongest absorption band is selected. The alignment of the molecules of the mixture is achieved by an alignment layer, as known to the person skilled in the art in the area of LC display technology. In order to eliminate influences by liquid-crystalline medium, other absorptions and/or reflections, each measurement is carried out against an identical mixture comprising no dye, and the value obtained is subtracted.

[0186] The measurement is carried out using linear-polarised light whose vibration direction is either parallel to the alignment direction (determination of E(p)) or perpendicular to the alignment direction (determination of E(s)). This can be achieved by a linear polariser, where the polariser is rotated with respect to the device in order to achieve the two different vibration directions. The measurement of E(p) and E(s) is thus carried out via the rotation of the vibration direction of the incident polarised light.

[0187] The degree of anisotropy R is calculated from the resultant values for E(s) and E(p) in accordance with the formula

R=[E(p)−E(s)]/[E(p)+2*E(s)],

[0188] as indicated, inter alia, in “Polarized Light in Optics and Spectroscopy”, D. S. Kliger et al., Academic Press, 1990. A detailed description of the method for the determination of the degree of anisotropy of liquid-crystalline media comprising a dichroic dye is also given in B. Bahadur, Liquid Crystals—Applications and Uses, Vol. 3, 1992, World Scientific Publishing, Section 11.4.2.

[0189] The quantity ∈.sub.iso is calculated as follows:

[0190] ∈.sub.iso=[E(p)+2*E(s)]/c/d, where the concentration c is selected in % and the cell thickness d is selected in cm.

[0191] A) Preparation of the Dyes

[0192] Compound V-5 is prepared in a synthetic process in accordance with the following Working Examples A-1 to A-5.

[0193] A-1) Synthesis of Compound V-1

##STR00041##

[0194] The metaborate is initially introduced in water, dibromide, THF, catalyst and hydrazine are added, and the mixture is stirred for 30 sec. The boronic acid is then added, and the mixture is heated to the boiling point (65° C.) and refluxed overnight. According to the thin-layer chromatogram TLC (heptane/EA 9:1), everything has reacted. The mixture is cooled, water and MTB ether are added, and the phases are separated. The aqueous phase is then extracted 6× with MTB ether (methyl tert-butyl ether), and the combined org. phases are washed 2× with water and 1× with sat. NaCl soln. and dried over sodium sulfate. Poor phase separation (black/black) is observed. The mixture is then evaporated to dryness. The residue is eluted over 200 ml of silica gel with heptane/toluene 1:1 (yield: 6.3 g, dark brown, solid; HPLC: 52.2%). The product is crystallised from 40 ml of toluene at −20° C. (3.56 g of ochre powder; HPLC: 91.7%).

[0195] The following tables summarise the starting materials employed, the product and the amounts employed and obtained.

TABLE-US-00002 Name Amount M Moles Equiv. 2,5-Dibromo-3,4-dinitrothiophene 13.200 g 331.928 39.768 mmol 1.0 Thiophene-2-boronic acid 11.195 g 127.958 87.489 mmol 2.2 Sodium metaborate tetrahydrate 21.929 g 137.860 0.159 mol 4.0 Bis(triphenylphosphine)palladium(II) 1.117 g 701.907 1.591 mmol 0.0 chloride (15.2% of Pd) for synthesis Tetrahydrofuran for analysis ACS 300.000 ml 72.106 3.703 mol 93.1 Hydrazinium hydroxide (about 80% of 0.135 ml 50.060 2.784 mmol 0.1 N.sub.2H.sub.5OH) for synthesis DI water 120.000 g 18.020 6.659 mol 167.5

TABLE-US-00003 Th. Product Amount M Content Moles Yield % yield 3′,4′-Dinitro- 3.560 g 338.385 91.7% 0.01 mol 24.3 13.5 g [2,2′;5′,2″]- terthiophene

[0196] A-2) Synthesis of Compound V-2

##STR00042##

[0197] Compound V-1, as prepared in accordance with Example A-1), is initially introduced in DMF under nitrogen, NBS is added with stirring, and the reaction mixture is heated to 90° C. and stirred at this temperature overnight. The reaction is carried out using an apparatus comprising 100 ml three-necked flask, magnetic stirrer, condenser, nitrogen inlet, thermometer and heating mantle.

[0198] The preparation of the novel product is evident in the TLC. Water is added to the still-warm product batch. The reaction mixture changes colour from red to dark brown. The mixture is subsequently cooled to 0° C., and crystals which have precipitated out are filtered off with suction, giving, as residue, 4.52 g of orange-brown powder (compound V-2; HPLC: 82.3%).

[0199] The following tables summarise the starting materials employed, the product and the amounts employed and obtained.

TABLE-US-00004 Name Amount M Moles Equiv. 3′,4′-Dinitro-[2,2′;5′,2″]terthiophene 3.500 g 338.385 10.343 mmol 1.0 N-Bromosuccinimide for synthesis 3.866 g 177.985 21.721 mmol 2.1 N,N-Dimethylformamide for analysis 40.000 ml 73.094 514.406 mmol 49.7

TABLE-US-00005 Yield Th. Product Amount M Content Moles % yield 5,5″-Dibromo- 4.520 g 496.177 82.3% 0.007 mol 72.5 5.1 g 3′,4′-dinitro- [2,2′;5′,2″]- terthiophene

[0200] A-3) Synthesis of Compound V-3

##STR00043##

[0201] The dibromide V-2 prepared in accordance with Example A-2) and boronic acid are initially introduced in 40 ml of toluene (under nitrogen). The carbonate solution is added to the batch. The catalyst and the ligand are subsequently added, and the mixture is heated to the boil and stirred under reflux overnight. According to a thin-layer check, everything has reacted. The batch is allowed to cool, and the aqueous phase is separated off. The aqueous phase is extracted once more with toluene. The combined org. phases are dried, filtered and evaporated in a rotary evaporator, giving 5.28 g of red-brown solid crude product, which is eluted through a 250 ml silica-gel frit with toluene/heptane 1:1. The two dark-red product fractions are combined and evaporated and crystallised from 35 ml of heptane/toluene 4:1. The product does not dissolve completely (−20° C.). The yield is 2.04 g of red flakes; HPLC: 80.0%. The product is crystallised from 25 ml of toluene at 0° C. Yield: 1.05 g of red flakes; HPLC: 92.8%. The product is crystallised again from 15 ml of toluene at −20° C. Yield: 0.88 g of red flakes; HPLC: 97.3%.

[0202] The following tables summarise the starting materials employed, the product and the amounts employed and obtained.

TABLE-US-00006 Name Amount Content M Moles Equiv. 5,5″-Dibromo-3′,4′-dinitro- 2.000 g 82.3% 496.177 3.317 mmol 1.0 [2,2′;5′,2″]terthiophene G5 boronic acid 1.590 g 210.053 7.570 mmol 2.3 Tris(dibenzylideneacetone)- 30.377 mg 915.700 0.033 mmol 0.0 dipalladium(0) Tris(o-tolylphosphine) 40.379 mg 304.300 0.133 mmol 0.0 Toluene, extra pure 40.000 ml 92.140 377.686 113.9 Sodium carbonate 13.269 ml 2.0 mol/l 105.988 26.539 8.0 (2M soln.)

TABLE-US-00007 No. Product Amount M Content Moles Yield % Th. yield 1 5,5″-Bis-(2-fluoro-4- 0.880 g 666.824 97.3% 0.001 mol 38.7 2.2 g pentylphenyl)-3′,4′- dinitro-[2,2′;5′,2″]- terthiophene

[0203] A-4) Synthesis of Compound V-4

##STR00044##

[0204] Compound V-3, as prepared in accordance with Example A-3), is converted into compound V-4 shown above. The dehydrogenation catalyst and the further starting materials are indicated in the table below. The nominal pressure is 4 bar/RT, the actual pressure is 4.4 bar/RT. The experiment duration is 38 h and the uptake of hydrogen is 230 ml. The product is filtered off with suction and transferred under argon. The hydrogenation solution is evaporated to dryness in a rotary evaporator, giving, as residue, 1.27 g of dark product, HPLC: 42.0%, conversion +40.9% according to the thin-layer chromatogram.

[0205] The following tables summarise the starting materials employed, the product and the amounts employed and obtained.

TABLE-US-00008 Name Amount Content M Moles Equiv. 5,5″-Bis-(2-fluoro-4- 0.900 g 97.3% 666.824 0.001 mol 1.0 pentylphenyl)-3′,4′- dinitro-[2,2′;5′,2″]- terthiophene Tetrahydrofuran for 20.000 ml 72.106 212.299 mmol 169.2 analysis 5% Pd/C E101 R 0.200 g (~54% H.sub.2O), Degussa Hydrogen 3.0 168.655 ml 22400.000 7.529 mmol 6.0

TABLE-US-00009 Yield Th. Product Amount M Content Moles % yield 5,5″-Bis- 1.270 g 606.858 42.0% 0.001 mol 70.0 0.8 g (2-fluoro-4- pentylphenyl)- [2,2′;5′, 2″]terthiophene- 3′,4′-diamine

[0206] A-5) Synthesis of Compound V-5

##STR00045##

[0207] Compound V-4, as prepared in accordance with Example A-4), is converted into compound V-5 according to the invention shown above.

[0208] The amine A-4) is initially introduced in the flask in pyridine under argon. The N-thionylaniline is added, and the mixture is stirred at 50° C. for 5 h. The mixture is subsequently cooled and stirred at room temperature over the weekend. According to the thin-layer chromatogram (toluene), conversion is complete, and a new green spot is obtained. MTB/toluene is added to the reaction mixture, which is washed a number of times with HCl/water. The organic phase is dried and evaporated to dryness in a rotary evaporator, giving, as crude product, 1.3 g of black-green oil. The crude product is eluted through a column with silica gel with heptane/chlorobutane 3:2, and a green spot is isolated: 270 mg of solid, dark-green product; HPLC: 94.9%. This is crystallised from 20 ml of toluene at −20° C., giving, as product, 222 mg of blue-green coal-like powder; HPLC: 96.2%. The structural formula V-5 is confirmed by means of mass spectroscopy and NMR.

[0209] The following tables summarise the starting materials employed, the product and the amounts employed and obtained.

TABLE-US-00010 Name Amount Content M Moles Equiv. 5,5″-Bis-(2-fluoro-4-pentyl- 1.270 g 42.0% 606.858 0.879 mmol 1.0 phenyl)[2,2′;5′,2″]terthiophene- 3′,4′-diamine Pyridine for analysis 10.000 ml 79.102 0.124 mol 141.0 N-Thionylaniline 0.390 g 139.176 0.003 mol 3.2

TABLE-US-00011 Yield Th. Product Amount M Content Moles % yield C.sub.34H.sub.32F.sub.2N.sub.2S.sub.4 220.000 634.892 96.2% 0.000 38.3 558.0 mg mg mol

Examples A-6 to A-8

[0210] Compound V-8 is prepared in a synthetic process, as shown in the following scheme, in accordance with the following Working Examples A-6) to A-8).

##STR00046##

[0211] A-6) Synthesis of Compound V-6

[0212] A mixture of compound 1 (2 g, 6 mmol), 4-butoxybiphenyl-4′-boronic acid (3.75 g, 13.3 mmol), sodium metaborate tetrahydrate (3.3 g, 24 mmol), bis(triphenylphosphine)palladium(II) chloride (169 mg, 0.24 mmol), THF (50 ml), water (22.5 ml) and hydrazine hydrate (0.02 ml, 0.42 mmol) is stirred at 65° C. for 18 h under a nitrogen atmosphere. The mixture is then subjected to conventional aqueous work-up, and the crude product is purified by filtration in toluene through a silica-gel frit (400 ml). Crystallisation from ethanol/toluene 9:1 (40 ml) at 0° C. gives V-6 as fine yellow needles (HPLC purity: 99.6%) in a yield of 16%.

[0213] A-7) Synthesis of Compound V-7

[0214] A solution of compound V-6 (900 mg, 1 mmol) in THF (10 ml) is hydrogenated in the presence of 5% Pd/C (200 mg) at 4 bar and RT until the theoretical amount of hydrogen has been taken up. The catalyst is filtered off, and the solution is evaporated to dryness in a rotary evaporator. The crude product V-7 is employed in the next synthesis step without further purification.

[0215] A-8) Synthesis of Compound V-8

[0216] The diamine V-7 (800 mg, 1.42 mmol) is dissolved in pyridine (10 ml) under an argon atmosphere, and N-thionylaniline (396 mg, 3 mmol) is added with stirring. The mixture is stirred at 50° C. for 17 h, subjected to conventional aqueous work-up, and the combined organic extracts are evaporated to dryness in a rotary evaporator. The crude product (2.5 g of blue-violet shimmering solid) is chromatographed in toluene through a silica-gel frit (300 ml) (540 mg, HPLC purity: 98.1%). Further purification is carried out by crystallisation from chlorobutane (50 ml) at −20° C. Yield: 466 mg (54%) of V-8 as dark-blue crystals.

[0217] A-9) Synthesis of Compound V-9

##STR00047##

[0218] Compound V-9) of the formula shown above is prepared analogously to Working Examples A-1) to A-5). Example A-3) is modified here by employing the corresponding boronic acid shown above.

[0219] B) Determination of the Properties of the Dyes

[0220] The dyes prepared are investigated with respect to their physical properties in order to establish their suitability for use in devices for regulating the transmission of energy. For comparison, the corresponding properties are indicated for compound D-1 (structure see below).

TABLE-US-00012 TABLE Structures of the dyes used [00048] Compound (1) [00049] Compound (8) [00050] Compound (9) [00051] D-1 [00052] D-2 [00053] D-3

TABLE-US-00013 TABLE Physical properties of the dyes Layer Host Band thickness Dye mixture Colour No. Conc. in % in μm λ.sub.max nm ε.sub.iso R D-1 M-1 red-violet 1 0.25 24.3 595 653 0.71 2 425 148 −0.07 Comp. (1) M-1 green 1 0.25 23.1 698 343 0.68 2 417 503 0.72 Comp. (8) M-1 blue 1 0.25 23.8 616 324 0.77 2 370 768 0.74 Comp. (9) M-1 green 1 0.25 23.6 717 335 0.71 2 413 545 0.72

[0221] The measurements show that the thienothiadiazole compounds according to the invention have excellent properties with respect to the degree of anisotropy R. In particular, the virtually identical degree of anisotropy in the second shorter-wave absorption band should be emphasised. The absorptions have positive dichroism both in the long-wave and in the shorter-wave band.

[0222] By contrast, comparative substance D-1 has positive dichroism in the longer-wave absorption band and slightly negative dichroism in the shorter-wave absorption band. A change in the dichroism thus takes place over the wavelengths. In a black mixture comprising a plurality of exclusively positively dichroic dyes using compound D-1, this negative value of D-1 in the region of the second band would then result in a reduction in the transmission range potentially achievable in a display. This would represent a disadvantage which is eliminated by the provision of the compounds according to the invention with their identical direction of the dichroism.

[0223] The compounds according to the invention exhibit different absorption colours depending on the substitution pattern, so that a mixture comprising two or more of the dyes according to the invention already covers a large part of the visible spectrum. If a red-absorbent dye is added as further dye, a black mixture can be obtained.

[0224] Some representatives of the dyes according to the invention exhibit a green colour, which can otherwise only be obtained by the combination of a yellow and blue dye. The use of green dyes can already give rise to black together with a red dye, so that the possibility exists of preparing black mixtures from just two different dyes.

[0225] C) Preparation of Liquid-Crystalline Media Comprising the Dyes

[0226] C-1) Preparation of LC Dye Mixtures LC-1 to LC-4

[0227] The example shows the possible preparation in principle of solutions of the compounds according to the invention in liquid-crystalline mixtures. The following dyes are added to the base mixture M-1 (see below) in the proportions indicated, and a solution is prepared:

TABLE-US-00014 TABLE LC dye mixtures LC-1 to LC-4 Dye Proportion LC-1 D-1 0.25% by weight LC-2 compound (1) 0.25% by weight LC-3 compound (8) 0.25% by weight LC-4 compound (9) 0.25% by weight

TABLE-US-00015 TABLE Composition of host mixture M-1 Clearing point 114.5° C. Delta-n 0.1342 n.sub.e 1.6293 n.sub.o 1.4951 Composition Compound CPG-3-F % by weight CPG-5-F 5 CPU-3-F 5 CPU-5-F 15 CP-3-N 15 CP-5-N 16 CCGU-3-F 16 CGPC-3-3 7 CGPC-5-3 4 CGPC-5-5 4 CCZPC-3-3 4 CCZPC-3-4 3 CCZPC-3-5 3

[0228] D) Use of Liquid-Crystalline Media Comprising Dye (1) According to the Invention in Devices for Regulating the Passage of Energy

[0229] In order to produce the devices, the liquid-crystal mixture comprising dye (1) is introduced into the interspace of the following layer arrangement: [0230] substrate layer [0231] ITO layer [0232] polyimide alignment layer [0233] interspace kept open using spacers [0234] polyimide alignment layer [0235] ITO layer [0236] substrate layer

[0237] The liquid-crystal layer in this arrangement is aligned in a planar manner with antiparallel pretilt angle. This alignment is achieved by two polyimide layers rubbed antiparallel to one another. The thickness of the liquid-crystalline layer is defined by spacers and is usually 25 μm.

[0238] Values for the degree of light transmission τ.sub.v for both the dark and bright switching states of the device are determined and are shown below. The bright switching state is achieved by application of a voltage, while the dark switching state is present without voltage. Furthermore, the colour location of the device (in CIE coordinates) in the dark and bright states is determined.

[0239] The measurement is carried out with the device comprising the liquid-crystalline medium with dyes in the measurement beam and a device of the same construction correspondingly without the dyes in the reference beam. Reflection and absorption losses of the cell are thereby eliminated.

[0240] The value τ.sub.v and the CIE coordinates (x,y) are defined as follows: τ.sub.v=degree of light transmission, determined in accordance with DIN EN410

[0241] The colour location (for white, grey, black) of the basic standard illuminant D65 here is at x=0.3127 and y=0.3290 (Manfred Richter, Einführung in die Farbmetrik [Introduction to Colorimetry], second edition 1991, ISBN 3-11-008209-8). The colour locations (x,y) indicated all relate to the standard illuminant D65 and the 2° standard observer in accordance with CIE 1931.

Device Example 1

[0242] The following liquid-crystalline mixture is used:

TABLE-US-00016 Constituent Proportion M-1 98.601% Compound (1) according to the invention 0.638% D-1 0.385% D-2 0.376%

[0243] Measurement values obtained for the device: [0244] dark state: x=0.313; y=0.329; τ.sub.v=35% [0245] bright state: x=0.313; y=0.333; τ.sub.v=66%

[0246] In the example, adequate solubility of the dyes in the liquid-crystalline medium is apparent. Furthermore, the example shows that the device can be switched from a dark state having significantly lower light transmission to a bright state having significantly increased light transmission by application of a voltage.

Device Example 2

[0247]

TABLE-US-00017 Constituent Proportion M-1 98.981% Compound (1) 0.600% D-3 0.419%

[0248] Measurement values obtained for the device: [0249] dark state: x=0.316; y=0.330; τ.sub.v=35% [0250] bright state: x=0.315; y=0.333; τ.sub.v=68.2%

[0251] In the example, adequate solubility of the dyes in the liquid-crystalline medium is apparent. Furthermore, the example shows that the device can be switched from a dark state having significantly lower light transmission to a bright state having significantly increased light transmission by application of a voltage. The example shows a black mixture consisting of only two dyes, a green dye and a red dye.