BIMESOGENIC COMPOUNDS AND MESOGENIC MEDIA

Abstract

The invention relates to bimesogenic compounds of formula I

##STR00001##

wherein R.sup.11, R.sup.12, MG.sup.1, MG.sup.2, X.sup.11, X.sup.12 and Sp.sup.1 have the meaning given in claim 1, to the use of bimesogenic compounds of formula I in liquid crystal media and in particular to flexoelectric liquid crystal devices comprising a liquid crystal medium according to the present invention.

Claims

1. A bimesogenic compound of formula I ##STR00183## wherein R.sup.11 and R.sup.12 respectively and independently denote a terminal group selected from H, F, Cl, CN, NCS and a straight-chain or branched alkyl group with 1 to 25 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups and optionally having one or more CH.sub.2 groups replaced, in each occurrence independently from one another, by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another, MG.sup.1 and MG.sup.2 respectively and independently denote a mesogenic group comprising one or more cyclic groups selected from aromatic, heteroaromatic, non-aromatic carbocyclic and/or non-aromatic heterocyclic groups, which are connected to each other directly and/or via (a) linking group(s), wherein the respective terminal group R.sup.11 or R.sup.12 is directly linked to a cyclic group of the mesogenic group, Sp.sup.1 denotes alkylene having 1, 3 or 5 to 40 C atoms, wherein optionally one or more CH.sub.2 groups are, respectively and independently, replaced by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, COS, SCO, CH(halogen)-, CH(CN), CHCH or CC, wherein respectively two O atoms, two CHCH groups and two groups selected from OCO, SCO, OCOO, COS and COO are not linked directly to one another, and X.sup.11 and X.sup.12 are independently from one another selected from a single bond, COO, OCO, OCOO, O, CHCH, CC, CF.sub.2O, OCF.sub.2, CF.sub.2CF.sub.2, CH.sub.2O, OCH.sub.2, COS, SCO, CSS, SCS, SCSS and S, wherein in X.sup.11-Sp.sup.1-X.sup.12 respectively two O atoms, two CHCH groups and two groups selected from OCO, SCO, OCOO, COS and COO are not linked directly to one another, provided that at least one of R.sup.11 and R.sup.12 is H, or provided that at least one of R.sup.11 and R.sup.12 is a straight-chain or branched alkyl group with 1 to 25 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups and optionally having one or more CH.sub.2 groups replaced, in each occurrence independently from one another, by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another, and further at least one of MG.sup.1 and MG.sup.2 exhibits in addition to the terminal group one or more substituents respectively and independently selected from F, Cl, CN, NCS, OCF.sub.3, CF.sub.3, SCH.sub.3, NO.sub.2, NH.sub.2, NHR.sup.c and NR.sup.cR.sup.d, wherein R.sup.c and R.sup.d each independently denote a straight-chain or branched alkyl group with 1 to 6 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups.

2. The bimesogenic compound according to claim 1, wherein MG.sup.1 and MG.sup.2 respectively and independently comprise at least one 6-atomic ring and optionally one, two or more 5-atomic rings, wherein in case of comprising two or more rings at least two of these rings are optionally linked by a 2-atomic linking group, preferably selected from COO, OCO, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, CH.sub.2CH.sub.2, CF.sub.2CF.sub.2, CHCH, CFCF and CC, more preferably COO, OCO, CH.sub.2O, OCH.sub.2, CF.sub.2O and OCF.sub.2, and wherein in MG.sup.1 and MG.sup.2 the respective cyclic groups directly connected to the respective terminal groups are respectively and independently 1,4-phenylene, wherein optionally one or two non-adjacent CH groups each may be replaced by an N atom, and which optionally is substituted by one or more substituents respectively and independently selected from F, Cl, CN, NCS, OCF.sub.3, CF.sub.3, SCH.sub.3, NO.sub.2, NH.sub.2, NHR.sup.c and NR.sup.cR.sup.d, wherein R.sup.c and R.sup.d each independently denote a straight-chain or branched alkyl group with 1 to 6 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups, and/or by one or more alkyl groups each independently having 1 to 9 C atoms and/or by one or more alkoxy groups each independently having 1 to 9 C atoms, or 1,4-cyclohexylene, wherein optionally one or two non-adjacent CH.sub.2 groups are replaced by O and/or S, and which optionally is substituted by one or more substituents respectively and independently selected from F, Cl, CN, NCS, OCF.sub.3, CF.sub.3, SCH.sub.3, NO.sub.2, NH.sub.2, NHR.sup.c and NR.sup.cR.sup.d, wherein R.sup.c and R.sup.d each independently denote a straight-chain or branched alkyl group with 1 to 6 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups and/or by one or more alkyl groups each independently having 1 to 9 C atoms and/or by one or more alkoxy groups each independently having 1 to 9 C atoms.

3. The bimesogenic compound according to claim 1, wherein at least one of MG.sup.1 and MG.sup.2 comprises a cyclic group selected from the structures represented by ##STR00184## and the mirror images thereof, wherein L, in each occurrence independently from one another, denotes F, Cl, CN, NCS, OCF.sub.3, CF.sub.3, SCH.sub.3, NO.sub.2, NH.sub.2, NHR.sup.c and NR.sup.cR.sup.d, wherein R.sup.c and R.sup.d each independently are a straight-chain or branched alkyl group with 1 to 6 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups.

4. The bimesogenic compound according to claim 1, comprising one of the structures represented by ##STR00185## wherein R.sup.11 denotes a terminal group selected from H, F, Cl CN, NCS and a straight-chain or branched alkyl group with 1 to 25 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups and optionally having one or more CH.sub.2 groups replaced, in each occurrence independently from one another, by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another, and L in each occurrence independently from one another, denotes F, Cl, CN, NCS, OCF.sub.3, CF.sub.3, SCH.sub.3, NO.sub.2, NH.sub.2, NHR.sup.c and NR.sup.cR.sup.d, wherein R.sup.c and R.sup.d each independently are a straight-chain or branched alkyl group with 1 to 6 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups, and wherein optionally R.sup.11 can be replaced by R.sup.12.

5. The bimesogenic compound according to claim 1, wherein at least one of MG.sup.1 and MG.sup.2 comprises a cyclic group selected from the structures represented by ##STR00186## and the mirror images thereof, wherein preferably said cyclic group is directly connected to the respective terminal group R.sup.11 or R.sup.12.

6. The bimesogenic compound according to claim 1, wherein at least one of R.sup.11 and R.sup.12 is H, preferably R.sup.11 and R.sup.12 are H.

7. The bimesogenic compound according to claim 1, wherein at least one of R.sup.11 and R.sup.12 is a straight-chain or branched alkyl group with 1 to 25 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups and optionally having one or more CH.sub.2 groups replaced, in each occurrence independently from one another, by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another, preferably R.sup.11 and R.sup.12, in each occurrence independently from one another, denote a straight-chain or branched alkyl group with 1 to 25 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups and optionally having one or more CH.sub.2 groups replaced, in each occurrence independently from one another, by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another.

8. The bimesogenic compound according to claim 1, wherein Sp.sup.1 is (CH.sub.2).sub.k, wherein k is 1, 3 or an integer from 5 to 15.

9. (canceled)

10. A liquid crystalline medium comprising one or more bimesogenic compounds according to claim 1.

11. The liquid crystalline medium according to claim 10, additionally comprising a chiral dopant.

12. The liquid crystalline medium according to claim 10, additionally comprising one or more compounds selected from the group of the compounds of formula II
R.sup.21-MG.sup.21-X.sup.21Sp.sup.2-X.sup.22MG.sup.22-R.sup.22 II wherein R.sup.21 and R.sup.22 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms, said alkyl group optionally being substituted by one or more halogen and/or CN groups and optionally having one or more non-adjacent CH.sub.2 groups replaced, in each occurrence independently from one another, by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC, MG.sup.21 and MG.sup.22 are each independently a mesogenic group, Sp.sup.2 is a spacer group comprising 5 to 40 C atoms, wherein one or more non-adjacent CH.sub.2 groups may be replaced by O, S, NH, N(CH.sub.3), CO, OCO, SCO, OCOO, COS, COO, CH(halogen)-, CH(CN), CHCH or CC, and X.sup.21 and X.sup.22 are each independently O, S, CO, COO, OCO, OCOO, CONH, NHCO, CH.sub.2CH.sub.2, OCH.sub.2, CH.sub.2O, SCH.sub.2, CH.sub.2S, CHCH, CHCHCOO, OCOCHCH, CC or a single bond, provided that the compounds of formula I are excluded from the compounds of formula II.

13. (canceled)

14. A liquid crystal device comprising a liquid crystalline medium which comprises two or more components, wherein at least one of the components is the bimesogenic compound according to claim 1.

15. The liquid crystal device according to claim 14, wherein the device is a flexoelectric device.

Description

COMPOUND AND SYNTHESIS EXAMPLES

Synthesis Example 1

[0266] Preparation of

##STR00161##

[0267] The compound of interest is prepared according to the following scheme.

##STR00162##

[0268] Stage 4

##STR00163##

[0269] 1-bromo-3-fluoroiodobenzene (27.5 g, 0.092 mol) is added to a round bottom flask containing tetrahydrofuran (30 mL). Diisopropylamine (30 mL) is added and the reaction is placed in an ultrasonic bath for 10 minutes. Catalysts, bis(triphenylphosphine)palladium(II) dichloride (0.9 g, 1.28 mmol) and copper (I) iodide (0.2 g, 1.05 mmol) are added and the reaction is cooled in a water bath to 20 C. 1,8-Nonadiyne (5.0 g, 0.041 mol) is slowly added to the reaction and stirred for a further 20 hours. The reaction is cooled and filtered under vacuum to remove precipitates. The filtrate is acidified with dilute hydrochloric acid and extracted with diethyl ether. The organic material is washed with water before concentrating to afford the product as a black solid. Pure product is obtained after column chromatography, eluting with dichloromethane/petroleum ether.

[0270] Stage 2

##STR00164##

[0271] Product of stage 1 (21.5 g, 0.040 mol) is dissolved in tetrahydrofuran (600 mL) and passed through a Thalesnano hydrogenator. Conditions of 70 bar pressure and 60 C. are used to produce the product as pale coloured solid.

[0272] Stage 3

##STR00165##

[0273] 1-Bromo-4-iodo-benzene (17.33 g; 61.25 mmol), (3-cyanophenyl)boronic acid (9.00 g; 61.25 mmol) are charged in a flask containing 400 mL tetrahyrofuran under nitrogen. Potassium carbonate (12.70 g; 91.87 mmol) in 20 mL water is added. The system is degassed and bis(triphenylphosphine)palladium(II) dichloride (0.90 g; 1.28 mmol; 0.02 eq.) is added. The reaction mixture is stirred at 80 C. overnight. Water (50 mL) and 20 mL dilute hydrochloric acid are added. Organic phase is separated and aqueous phase is extracted with ethyl acetate (3100 mL). Organic phases are combined, dried over magnesium sulphate and evaporated under reduced pressure. Purification by plug of silica eluted by dichloromethane followed by crystallisation from IMS gives pure product.

[0274] Stage 4

##STR00166##

[0275] 4-Bromo-biphenyl-3-carbonitrile (10.50 g; 40.68 mmol), 4,4,5,5,4,4,5,5-octamethyl-[2,2]bi[[1,3,2]dioxaborolanyl] (11.36 g; 44.75 mmol) and potassium acetate (5.94 g; 60.65 mmol) are added to 200 mL anhydrous 1,4-dioxane. The system is degassed, dichlorobis(tricyclohexylphosphine)palladium (II) (1.50 g; 2.03 mmol) is added and the reaction mixture is stirred at 80 C. overnight. Water (30 mL) is added and organic phase is separated. Aqueous phase is extracted three times with ethyl acetate. Organic phases are combined and washed with brine, then twice with water, dried over magnesium sulphate and concentrated. Purification by column chromatography over silica gel eluted with petroleum ether/dichloromethane (5:1 ratio), followed by recrystallisation from petroleum ether/IMS gives pure product as white solid.

[0276] Stage 5

##STR00167##

[0277] To a solution of 4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-biphenyl-3-carbonitrile (9.65 g; 31.63 mmol) and 1-bromo-4-[9-(4-bromo-3-fluoro-phenyl)nonyl]-2-fluoro-benzene (7.50 g; 15.82 mmol) in 100 mL tetrahydrofuran, sodium metaborate octahydrate (6.83 g; 24.78 mmol) in 20 mL water is added. The system is purged with nitrogen and bis(triphenylphosphine)palladium(II) dichloride (0.28 g; 0.40 mmol) is added and the reaction mixture is stirred at 80 C. overnight. Water (20 mL) is added and organic phase is separated. Aqueous phase is extracted with ethyl acetate. Organic phases are combined, washed with dilute hydrochloric acid followed by water and evaporated under reduced pressure. Crystallisation from dichloromethane/acetonitrile gives pure product.

[0278] Phase sequence: K 124 I, e/K=1.96 V.sup.1.

Synthesis Example 2

Synthesis Example 2a

[0279] Preparation of

##STR00168##

[0280] The compound of interest is prepared according to the following scheme.

##STR00169##

[0281] Stage 1

##STR00170##

[0282] To a solution of 1-bromo-4-iodo-benzene (25.00 g; 88.37 mmol) in 80 mL tetrahydrofuran, bis(triphenylphosphine)palladium(II) dichloride (0.90 g; 1.28 mmol), copper(I) iodide (0.20 g; 1.05 mmol) and diisopropylamine (14.00 ml; 99.61 mmol) are added. The reaction mixture is purged with nitrogen. Then, nona-1,8-diyne (5.00 g; 41.60 mmol) in 20 mL tetrahydrofuran is added slowly. The reaction is stirred overnight at room temperature. Reaction mixture is filtered and the solid washed with tetrahydrofuran. The solvent is removed under reduced pressure. Column chromatography of crude on silica gel eluted with dichloromethane gives product as yellow solid.

[0283] Stage 2

##STR00171##

[0284] 1-bromo-4-[9-(4-bromophenyl)nona-1,8-diynyl]benzene (30.00 g; 69.74 mmol), (3,5-difluorophenyl)boronic acid (24.23 g; 153.43 mmol), bis(triphenylphosphine)palladium(II) dichloride (2.45 g; 3.49 mmol) are charged into a flask containing 600 mL tetrahydrofuran. Aqueous solution of sodium carbonate (2 M, 139.48 ml; 278.96 mmol) is added. The reaction mixture is degassed and stirred at 80 C. overnight. Organic layer is separated, dried over magnesium sulphate and evaporated under reduced pressure. Column chromatography of crude on silica gel eluted with petroleum ether/dichloromethane (4:1 ratio) gives pure product.

[0285] Phase sequence: K 115 I, e/K=1.72 V.sup.1.

Synthesis Example 2b

[0286] Preparation of

##STR00172##

[0287] The compound of interest is prepared according to the following scheme.

##STR00173##

[0288] Stages 1 and 2 are carried out as in Example 2a.

[0289] Stage 3

##STR00174##

[0290] 1-[4-[9-[4-(3,5-difluorophenyl)phenyl]nona-1,8-diynyl]phenyl]-3,5-difluoro-benzene (7.00 g; 1.00 eq.) in 100 mL methanol/tetrahydrofuran (1:1 ratio) is pumped four times through the H-Cube using 10% Pd/C as catalyst. The pressure of the system is set to 10 bar, flow rate 10 mL/min and the temperature to 30 C. The solvent is removed under reduced pressure, affording the product as white crystals.

[0291] Phase sequence: K 46 I, e/K=2.0 V.sup.1.

Synthesis Example 3

[0292] Preparation of

##STR00175##

[0293] The compound of interest is prepared according to the following scheme.

##STR00176##

[0294] Stage 1 is carried out as in Example 2a.

[0295] Stage 2

##STR00177##

[0296] 1-Bromo-4-[9-(4-bromophenyl)nona-1,8-diynyl]benzene (8.00 g; 18.60 mmol) and (3-cyanophenyl)boronic acid (5.88 g; 40.00 mmol) are charged into a flask containing 1,4-dioxane (200.00 mL). [1,1-Bis(diphenylphosphino)ferrocene]dichloropalladium(II), complex with dichloromethane (0.50 g; 0.68 mmol), sodium carbonate (10.60 g; 100.00 mmol) and water (50.00 mL) are added. The reaction mixture is degassed and stirred at 80 C. for 3 h. The reaction is cooled to room temperature and 100 mL ethyl acetate is added. Organic phase is separated, washed with brine then water, and evaporated under educed pressure. Column chromatography of crude on silica gel eluted with petroleum ether/dichloromethane (7:3 ratio) gives product.

[0297] Stage 3

##STR00178##

[0298] 3-[4-[9-[4-(3-cyanophenyl)phenyl]nona-1,8-diynyl]phenyl]benzonitrile (1.50 g; 1.00 eq.) in 100 mL methanol is pumped through the H-Cube using 10% Pd/C as catalyst. The pressure of the system is set to 30 bar, flow rate 3 mL/min, and the temperature to 30 C. The solvent is removed under reduced pressure. Crystallisation from acetonitrile gives pure product.

[0299] Phase sequence: K 84 I.

Synthesis Example 4

[0300] Preparation of

##STR00179##

[0301] The compound of interest is prepared according to the following scheme.

##STR00180##

[0302] Stage 1

##STR00181##

[0303] 4-Bromo-phenol (11.77 g; 68.05 mmol; 1.00 eq.), (3-cyanophenyl)boronic acid (10.00 g; 68.06 mmol) are charged to a flask containing 1,4-dioxane (200.00 mL). [1,1-Bis(diphenylphosphino)ferrocene]dichloropalladium(II), complex with dichloromethane (0.50 g; 0.68 mmol), sodium carbonate (14.31 g; 0.14 mol) and water (50.00 mL) are added. The reaction mixture is degassed and stirred overnight at 80 C. Ethyl acetate (100 mL) is added. Organic phase is separated, washed with brine then water, dried over magnesium sulphate and evaporated under educed pressure. Recrystallisation from dichloromethane/ethyl acetate (1:4 ratio) gives product.

[0304] Stage 2

##STR00182##

[0305] Undecanedioic acid (2.88 g; 13.30 mmol) acid is added to a flask containing 100 mL toluene. 4-Hydroxy-biphenyl-3-carbonitrile (5.20 g; 26.64 mmol), N,N-dicyclohexylcarbodiimid (5.57 g; 27.00 mmol) and 4-(dimethylamino)-pyridine (0.61 g; 5.00 mmol) are added and stirred overnight at room temperature. Water (50 mL) is added and organic phase is separated, dried over magnesium sulphate and evaporated under reduced pressure. Column chromatography of crude on silica gel eluted with petroleum ether/dichloromethane (3:2 ratio) followed by recrystallisation from petroleum ether/ethyl acetate gives pure product.

[0306] Phase sequence: K 125 (N 84) I, e/K=1.9 V.sup.1.

[0307] The above compounds have suitable phase behaviour and flexoelastic ratios and can be useful components in liquid crystal media as shown below, and can in particular be useful to tune the working temperature of high e/K mixtures with regard to the flexoelectric effect.

Use Examples, Mixture Examples

[0308] Phase transitions, including clearing point, are initially measured using Differential Scanning Calorimetry (DSC).

[0309] Furthermore, typically a 5.6 m thick cell having an anti-parallel rubbed PI alignment layer is filled on a hotplate at a temperature at which the flexoelectric mixture is in the isotropic phase.

[0310] After the cell has been filled phase transitions, including clearing point, are verified by optical inspection. For optical phase transition measurements, a Mettler FP90 hot-stage controller connected to a FP82 hot-stage is used to control the temperature of the cell. The temperature is increased from ambient temperature at a rate of 5 C. per minute until the onset of the isotropic phase is observed. The texture change is observed through crossed polarizers using an Olympus BX51 microscope and the respective temperature is noted.

[0311] Wires are then attached to the ITO electrodes of the cell using indium metal. The cell is secured in a Linkam THMS600 hot-stage connected to a Linkam TMS93 hot-stage controller. The hot-stage is secured to a rotation stage in an Olympus BX51 microscope.

[0312] The cell is heated until the liquid crystal is completely isotropic. The cell is then cooled under an applied electric field until the sample is completely nematic. The driving waveform is supplied by a Tektronix AFG3021B arbitrary function generator, which is sent through a Newtons4th LPA400 power amplifier before being applied to the cell. The cell response is monitored with a Thorlabs PDA55 photodiode. Both input waveforms and optical response are measured using a Tektronix TDS 2024B digital oscilloscope.

[0313] In order to measure the flexoelastic response of the material, the change in the size of the tilt of the optical axis is measured as a function of increasing voltage. In this connection the following equation is used

[00001]$\tan .Math..Math.=\frac{P_0}{2.Math.}.Math.\frac{e}{K}.Math.\underset{\_}{E}$

wherein is the tilt in the optical axis from the original position (i.e. when E=0), E is the applied field, K is the elastic constant (average of K.sub.1 and K.sub.3) and e is the flexoelectric coefficient, wherein e=e.sub.1+e.sub.3. The applied field is monitored using a HP 34401A multimeter. The tilt angle is measured using the aforementioned microscope and oscilloscope. The undisturbed cholesteric pitch, P.sub.0, is measured using an Ocean Optics USB4000 spectrometer attached to a computer. The selective reflection band is obtained and the pitch is determined from the spectral data.

[0314] The mixtures according to the invention shown in the following examples are well suitable for use in flexoelectric displays. To achieve a suitable cholesteric pitch appropriate concentrations of chiral dopant or dopants can be used.

Reference Mixture Example 1

[0315] The host mixture H-0 is prepared and investigated, inter alia studying its properties for alignment.

TABLE-US-00006 Composition Compound No. Abbreviation Conc./% 1 F-PGI-O-9-O-GP-F 25.0 2 F-PGI-O-9-O-PP-N 25.0 3 F-PGI-ZI-9-Z-GP-F 25.0 4 F-PGI-ZI-9-Z-PP-N 25.0 100.0

[0316] The alignment of the mixtures is determined in a test cell with anti-parallel rubbed PI orientation layers, for planar alignment, having a cell gap of 10 m at a wavelength of 550 nm. The optical retardation of the samples is determined using an ellipsometer instrument for various angles of incidence ranging from 60 to +40.

[0317] The results for H-0 are compiled in the following table, wherein the sample H-0 shows an optical retardation of 25 nm under perpendicular observation, i.e. at an angle of incidence of 0. This already indicates the presence of a homogeneous alignment. For various angles of incidence the values of the retardation range from 2 nm to 55 nm. Although scattering, as a function of the angle of incidence, is quite significant, there appears to be a trend for the retardation to increase with increasing angle of incidence. However, the significant scatter of the retardation values indicates a rather poor quality of the homeotropic alignment.

TABLE-US-00007 Angle/ 60 40 20 0 20 40 Mixt. d .Math. n/nm 2 33 42 25 55 44 H-0

Comparative Mixture Example 1

[0318] Mixture C-1

[0319] 2% of the chiral dopant R-5011 are added in the mixture H-0 giving the mixture C-1, which is investigated for its properties.

TABLE-US-00008 Composition Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 F-PGI-O-9-O-GP-F 24.5 3 F-PGI-O-9-O-PP-N 24.5 4 F-PGI-ZI-9-Z-GP-F 24.5 5 F-PGI-ZI-9-Z-PP-N 24.5 100.0

[0320] The mixture C-1 may be used for the USH mode. It has a clearing point of 82 C. and a lower transition temperature [T(N2,N)] of 33 C. It has a cholesteric pitch of 301 nm at 35 C. The e/K of this mixture is 1.9 Cm.sup.1N.sup.1 at a temperature of 34.8 C.

Mixture Example 1

[0321] In a mixture of H-0 10% of the compound of Synthesis Example 1 and 2% of chiral dopant are comprised to give mixture M-1, which is investigated.

TABLE-US-00009 Composition Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 F-PGI-O-9-O-GP-F 22.0 3 F-PGI-O-9-O-PP-N 22.0 4 F-PGI-ZI-9-Z-GP-F 22.0 5 F-PGI-ZI-9-Z-PP-N 22.0 6 Compound 1* 10.0 100.0 Remark: *) Compound of Synthesis Example 1.

[0322] This mixture M-1 is well suitable for the USH mode.

[0323] It has a cholesteric pitch of 307 nm at 40.2 C.

[0324] The e/K of this mixture is 1.96 Cm.sup.1 N.sup.1 at a temperature of 39.3 C.

Mixture Example 2

[0325] In a mixture of H-0 10% of the compound of Synthesis Example 2a and 2% of dopant are comprised to give mixture M-2, which is investigated.

TABLE-US-00010 Composition Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 F-PGI-O-9-O-GP-F 22.0 3 F-PGI-O-9-O-PP-N 22.0 4 F-PGI-ZI-9-Z-GP-F 22.0 5 F-PGI-ZI-9-Z-PP-N 22.0 6 Compound 2a* 10.0 100.0 Remark: *) Compound of Synthesis Example 2a.

[0326] This mixture M-2 is well suitable for the USH mode. It has a cholesteric pitch of 311 nm at 40 C. The e/K of this mixture is 1.72 Cm.sup.1N.sup.1 at a temperature of 39.3 C.

Mixture Example 3

[0327] In a mixture of H-0 10% of the compound of Synthesis Example 2b and 2% of chiral dopant are comprised to give mixture M-3, which is investigated.

TABLE-US-00011 Composition Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 F-PGI-O-9-O-GP-F 22.0 3 F-PGI-O-9-O-PP-N 22.0 4 F-PGI-ZI-9-Z-GP-F 22.0 5 F-PGI-ZI-9-Z-PP-N 22.0 6 Compound 2b* 10.0 100.0 Remark: *) Compound of Synthesis Example 2b.

[0328] This mixture M-3 is well suitable for the USH mode. It has a cholesteric pitch of 277 nm at 35 C. The e/K of this mixture is 2.00 Cm.sup.1N.sup.1 at a temperature of 36.6 C.