WO2004048499A2 - Combined rod-disc crystalline systems with nematic properties - Google Patents

Abstract

A liquid crystal compound comprising a discotic nematic phase promoting moiety, comprises a disc shaped mesogen, and at least two calamitic nematic phase moieties, comprising rod shaped mesogens.

Description

Combined rod - disc systems with unusual nematic properties

This invention relates to novel liquid crystals, to methods of their manufacture and to uses thereof.

The term "liquid crystals" is well known. It refers to compounds which, as a result of their structure, will align themselves in a similar orientation, preferably at working temperatures, for example of from -40 to 200°C. These materials are useful in various devices, in particular liquid crystal display devices or LCDs.

Liquid crystals can exist in various phases, hi essence there are three different classes of liquid crystalline material, each possessing a characteristic molecular arrangement. These classes are nematic, chiral nematic (cholesteric) and smectic.

Broadly speaking, the molecules of nematic compounds will align themselves in a particular orientation in a bulk material. Smectic materials, in addition to being orientated in a similar way, will align themselves closely in layers.

A wide range of smectic phases exists, for example smectic A and smectic C. h the former, the molecules are aligned pe endicularly to a base or support, whilst in the latter, molecules may be inclined to the support. Some liquid crystal materials possess a number of liquid crystal phases on varying the temperature. Others have just one phase. For example, a liquid crystal material may show the following phases on being cooled from the isotropic phase:- isotropic - nematic - smectic A - smectic C - solid. If a material is described as being smectic A then it is generally taken to mean that the material possesses a smectic A phase over a useful working temperature range.

Such materials are useful, in particular in display devices where their ability to align themselves and to change their alignment under the influence of voltage, is used to impact on the path of polarised light, thus giving rise to liquid crystal displays. These are widely used in devices such as watches, calculators, display boards or hoardings, computer screens, in particular laptop computer screens etc. The properties of the compounds which impact on the speed with which the compounds respond to changes in voltage include molecule size, viscosity (Δn), dipole moments (Δε), conductivity etc.

A typical liquid crystal device comprises a layer of liquid crystal material (typically a mixture) sandwiched between two cell walls. On the inner surfaces of the cell walls are electrode structures and on the inner surface of the electrode structures is a so called alignment layer. This alignment layer serves to align the liquid crystal material in a particular manner such that the switching characteristic of the device may be optimised. There are various types of methods of providing alignment layers including rubbing the surface in a particular direction, typically with a cloth. Alternatively there are so called non contact alignment layers wherein a layer of material is deposited on to the inner electrode surface(s) which has the effect of imparting a particular alignment characteristic on to the liquid crystal material. These alignment techniques are well known to those skilled in the art and there is a continued effort in developing improved methods of alignment.

There is also a continued need for alternative liquid crystal materials which show improved properties in the bulk liquid crystal layer.

Nematic liquid crystals are the backbone of the display industry and applications are centred on the ability to orient the nematic director in a sample via the application of electromagnetic fields. Theoretical predicted for more than 30 years and attempted to realise experimentally by numerous research groups is the biaxial nematic phase. In a deviation from the overall cylinder envelope with one director such materials are expected to have a board like envelope with the potential to use two directors (orientations). A theoretical prediction of the biaxial nematic phase is the miscibility of nematic disc and rod-shaped molecules - an experimental result for our materials. The potential uses of such materials have been, -apart form the fundamental scientific importance been the driving force for continuous research efforts. Important technological advantages of the materials are associated with the option for completely new device construction and addressing schemes, so far however the expectations are that this phase allows for the alignment of one director in matrices e.g. polymer matrices and the time resolved switching of the second molecular orientational axis. As polymers can be oriented and fabricated into large areas, this opens the option for a construction of large area devices, using essentially conventional spinning techniques. A further advantage is the mechanical flexibility of such systems.

Additional technological benefits of the materials are associated with their electron rich structure allowing for fluorescence, and application in the area of light emitting diodes. Attractive, in conjunction with a chiral nematic phase, particularly, is their use in LC lasers, where the emitting wavelength can be controlled either by distorting the cholesteric helix with an electromagnetic field or in elastomers via a mechanical field.

The majority of liquid crystals are built up from either a rod-shaped (calamitic) or a disc-shaped (discotic) core. Both structures can form nematic mesophases, wherein the mesogens only display orientational order and no positional order. In the 'nematic calamitic phase (Ncai),' the long axis of the mesogens is aligned to the director fi, whereas in the 'nematic discotic phase (No),' the short axis of the mesogens is aligned to the director, see Figure 1.

From, a symmetry point of view, both nematic phases are the same, in fact indistinguishable, and because of this, they should be able to mix in mixing experiments solely out of symmetry considerations. However, because of their pronounced dissimilar shape, mixing of the ND_ΪSC and the Ncai phase has never been observed experimentally. Minor differences between the NDJ_SO and the Nc_aι phases are that - by definition - the N_DJ_SC phase is diamagnetically negative, whereas the Ncai phase are positive. The birefringence (An ≡ n_e ~n₀) of most DI_SC phases is negative, and po sitive for the nearly all Ncai phases . Theoreticians have proposed that the nematic biaxial phase may occur in mixtures of disc-shaped and rod-shaped particles.¹ However, since the both are immiscible in practise, the N_B phase has never been observed experimentally in such systems.

The present invention is based on the surprising experimental result that mixed molecular systems, composed of at least one disc-shaped moiety, promoting the formation of the discotic nematic (N_D;_SC) phase, and more than one rod-shaped groups, promoting the formation of the calamitic nematic (Nc_ai) phase, wherein the groups are linked by a flexible spacer, show nematic phases. In the nematic phase, a continuous miscibility over the full concentration range is observed for mixtures of the disc-rod combined mesogen with the disc-shaped and the rod-shaped precursor mesogens.

It is known that this behaviour is a precondition for the formation of the nematic biaxial (N_B) phase; thus these mixtures might exhibit N_B phase behaviour and could be incorporated in devices making use of the particular properties of the N_B phase.

We have prepared a series of novel liquid crystals by connecting discotic and calamitic moieties,² see Figure 2. Here, we also describe the mesomorphic properties of the combined liquid crystals, their constituents as well as the properties of some of their mixtures.

According to a first aspect of the invention we provide a liquid crystal which comprises a discotic nematic phase promoting, moiety and at least two calamitic nematic phase promoting moieties.

In a preferred aspect of the invention the discotic nematic phase promoting moiety comprises a disc shaped moiety. Furthermore, each of the at least two calamitic nematic phase promoting moieties comprise rod shaped moieties. In an especially preferred aspect of the invention the liquid crystal comprises a compound of formula I. Such compounds are novel per se, thus we provide a compound of formula I;

Formula I in which R is X or hydrogen or is represented by formula II provided that at least one group is represented by formula II;

Formula II

wherein Di is selected from the following rings or fused ring systems:

each of which may optionally be substituted in at least one of the available positions with one or more of a substituent selected from the group F, CI, Br, CN, NO , Li, OL and SL₃;

Ei is selected from the group; single bond, -CO2-, -OCO-, -CH₂CH₂- -CH=CH- -C≡C- -CH₂O- -OCH₂- -CH₂S- -SCH₂- -CN=N- -N=CH- -N=N- OCO(CH₂)_c and CO₂(CH₂)_c; Yi is selected from the group; single bond, O, S, CH₂, CO₂, OCO, CONH, NHCO, NH and-(C=O)-;

Ti is selected from the group; H, CN, F, CI, CF₃, NO₂, NCS, SCN, L₄, OL₅, SL₆, CO₂L₇, OCOLs; X is represented by formula IH;

rod-shaped

-rg-^Q— n — [Z]-t-^Q ₂ mesogen m

Formula III

wherein [Z] which may be a bond or is optionally a branching group, provided that when it is not a branching group then at least one R in Formula I is a group X, and when [Z] is a branching group it is selected from Ei or is an aromatic or aliphatic multifunctional moiety, selected from one of the structures of formula V;

Formula V ^t Substitution may be on any available position. [Y₂], [Y₃] and [Y₄], which may be the same or different, are each selected from the ^' group; single bond, H, O, S, CH₂, CO₂, OCO, CONH, NHCO, NH, -(C=O)-, CH₂O,

CH₂CH₂O, CH₂OCO, CH₂CH₂OCO;

Qi and Q₂, which may be the same or different, are each selected from the group; (CH₂)_g, (CF₂)_h, (CH₂CH₂O)iCH₂CH₂ and (SiZ^-SiZ², ,

Z and Z , which may be the same or different, are each selected from CH₃, CF₃ and

H;

Li, L₂ and L₃, which may be the same or different, are each a C₁-₅ branched or straight alkyl chain; L₄, L₅, L₆, L₇ and L₈, which may be the same or different, are each a Ci.iβ straight or branched alkyl chain; c is an integer from 1 to 4; g and h, which may be the same or different, are each an integer from 1 to 20; i and j, which may be the same or different, are each an integer from 1 to 10; and m is an integer from 1 to 5.

The rod-shaped mesogen may be an end-on rod-shaped mesogen or a side-on rod- shaped mesogen.

When the rod-shaped mesogen is an end on rod-shaped mesogen it is preferably a compound of formula IV. When the rod-shaped mesogen is a side-on rod-shaped mesogen it is preferably a compound of formula IVa;

end-on rod-shaped mesogen - formula IV

side-on rod-shaped mesogen (a + b = 1 ) - formula IVa

In the formulae IN and INa, D₂, D₃, D₄ and D₅, which may be the same or different, are each selected from the following groups; -

each of which may optionally be substituted in at least one of the available positions with one or more of the following substituents: F, CI, Br, CΝ, ΝO₂, L₉, OLio and

SLn;

E₂, E₃ and E₄, which may be the same or different, are each selected from the group; single bond, ~CO₂~, -OCO-, -CH₂CH₂- -CH=CH- -C≡C-

-CH₂O-, -OCH₂-, -CH2S- -SCH2- -CN=N- -N=CH-, -N=N-, OCO(CH₂)_f and CO₂(CH₂)_f ;

T₂ and T₃, which may be the same or different, are each selected from the group; H,

CN, F, CI, CF₃, NO₂, NCS, SCN, L_u, OL13, SL_!4, CO₂Lι₅ and OCOLι₆,

L₉, Lio and Lπ, which may be the same or different, are each selected from a C₁-5 branched or straight alkyl chain; L₁₂, L₁₃, Lι , L₁₅ and Lι₆, which may be the same or different, are each a C_M6 straight or branched alkyl chain; and f is an integer from 1 to 4. In side-on rod-shaped mesogens, the rings D₃ or D₅ are substituted by a spacer of type Q₂ in one of the available positions.

The mesogenic group may also be given by cholesteryl groups of derivatives thereof.

Ti, T₂ and/or T₃may include one or more non-adjacent CH₂ groups that are substituted with CH(CN), CH(CF₃), CH(C1) CH(CH₃) in chiral or non-chiral form and/or one or more non-adjacent CH₂ groups that are substituted by CH such that there is a double bond present and the terminal CH₃ group may be replaced by a CH₂ group.

Spacers of the type Qi and Q₂ may be compiled from the fragments described before.

Preferred disc-shaped mesogens are ll-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl alcohol or ll-[pent-ikis(4-hexyloxyphenyletynyl)phenoxy] undecyl alcohol. Alternatively, disc-shaped mesogens may include tetrakis-(alkyl phenyl ethynyl phenoxy (undecyl alcohol) compounds.

hi a preferred aspect of the invention we particularly provide a compound as hereinbefore described selected from the group consisting rod-disc mesogens as hereinbefore described when the rod-shaped mesogen is selected from the group comprising; 3,4,5-tris[6-(4'-cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid ethyl ester; 3,4,5-tris[10-(4'-cyanobiphenyl-4-yloxy)decyloxy]benzoic acid ethyl ester; 3,4- bis[6-(4'-cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid ethyl ester; 3,4,5-tris[6-(4-(4- pentylphenylazo)phenoxy)decyloxy]ber-zoic acid ethyl ester; and 3,4,5-tris[6-(2,3- difluoro-4"-octyloxy-[l,r;4',r']terphenyl-4-yloxy)hexyloxy]benzoic acid ethyl ester.

Thus an especially preferred mixed disc-rod mesogen of the invention comprises an ester formed between ll-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl alcohol or ll-[pentakis(4-hexyloxyphenyletynyl)phenoxy] undecyl alcohol and a compound selected from the group comprising; 3,4,5-tris[6-(4'-cyanobiphenyl-4- yloxy)hexyloxy]benzoic acid; 3,4,5-tris[10-(4'-cyanobiphenyl-4- yloxy)decyloxy]benzoic acid; 3,4-bis[6-(4'-cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid; 3,4,5-tris[6-(4-(4-pentylphenylazo)phenoxy)decyloxy]benzoic acid; and 3,4,5- tris[6-(2,3-difluoro-4"-octyloxy-[l , 1 ';4', 1 "]terphenyl-4-yloxy)hexyloxy]benzoic acid.

In an especially preferred aspect of the invention we particularly provide a compound as hereinbefore described selected from the group consisting of 3,4,5-tris[6-(4'- cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid 1 l-[pentakis(4-methoxyphenyletynyl)- phenoxy] undecyl ester; 3,4,5-tris[10-(4'-cyanobiphenyl-4-yloxy)decyloxy]benzoic acid ll-[pent--kis(4-methoxyphenyletynyl)phenoxy] undecyl ester; 3,4,5-tris[6-(4'- cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid 1 l-[pentakis(4-hexyloxy- phenyletynyl)phenoxy] undecyl ester; 3,4,5-tris[10-(4'-cyanobiphenyl-4- yloxy)decyloxy]benzoic acid l l-[pent--kis(4-hexyloxyphenyletynyl)phenoxy] undecyl ester; 3,4-bis[10-(4'-cyanobiphenyl-4-yloxy)decyloxy]benzoic acid ll-[pentakis(4- methoxyphenyletynyl)phenoxy] undecyl ester; 3,4,5-tris[6-(4-(4- pentylphenylazo)phenoxy)hexyloxy]benzoic acid 1 l-[pentakis(4-methoxy- phenyletynyl)phenoxy] undecyl ester; and 3,4,5-tris[6-(2,3-difluoro-4"-octyloxy- [l,r;4',l"]terphenyl-4-yloxy)hexyloxy]benzoic acid 1 l-[ρentakis(4- methoxyphenyletynyl)phenoxy] undecyl ester.

A specifically preferred compound which may be mentioned is a compound of formula D 1 R5, 3,4,5-tris[6-(2,3-difluoro-4"-octyloxy-[ 1 , 1 ';4', 1 "]terphenyl-4- yloxy)hexyloxy]benzoic acid ll-[ρentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester.

According to a further aspect of the invention, we further provide the use of one or more of the compounds hereinbefore described in the manufacture of a liquid crystal.

According to this aspect of the invention we provide the use of a compound as hereinbefore described in the manufacture of a liquid crystal that exhibits a nematic phase, e.g. a liquid crystal that exhibits a uni-axial nematic phase, a biaxial nematic phase, a chiral nematic phase, a smectic A phase, a smectic C phase or a chiral smectic C phase.

The use may also comprise the manufacture of a liquid crystal containing discotic nematic liquid crystal components or containing discotic nematic and calamitic liquid crystal components.

The use may also comprise the manufacture of a transmissive or reflective device, e.g. where the molecules are in a biaxial nematic phase.

In the liquid crystal of the invention, the two directors of the nematic phase can be oriented selectively and independently.

We further provide the use of one or more compounds as hereinbefore described in the manufacture of a liquid crystal which comprises a polymer so that one of the nematic directors of the mixture is oriented by the polymer the other can be oriented by electromagnetic fields allowing for mechanically flexible devices and for devices where a preferred orientation by a alignment of the polymer matrix; the design of very large area devices without alignment problems.

We also provide the use of a compound in the manufacture of a device comprising two spaced cell walls, each bearing electrode structures on at least one facing surface treated with an alignment layer, a layer of liquid crystal material enclosed between the cell walls, characterised that it incorporates a liquid crystal or a liquid crystal mixtures mixture containing nematic liquid crystal.

The use may comprise the manufacture of a device comprising two spaced cell walls whose transparency in the electromagnetic spectrum is dissimilar, at least one bearing electrode structures on at least one facing surface treated with an alignment layer, a layer of liquid crystal material enclosed between the cell walls, characterised that it incorporates a liquid crystal or a liquid crystal mixtures mixture containing nematic liquid crystal.

The use may further comprise the manufacture of a data storage, memory, or 3D memory device and/or data and processing systems of which optical or holographic devices are examples; a laser, where the wavelength of the emitted radiation can be varied by the variation of the pitch of the cholesteric helix performed by the application of an electric field or temperature, or where cholesteric elastomers are used by the application of a mechanical field or temperature; a data transmission device; an optical switch; an optical data transmission device for the alignment of the liquid crystal mixtures; a laser; an opto-electrical switch; an optical computing system; a component in protective devices for radiation; a medical diagnostic device; a light emissive device; a lithographic device; a photovoltaic cell andor a molecular logic gate.

Alternatively the use may comprise the manufacture of a paint.

In a further alternative of the present invention, the use may comprise the use as a material as a bulk heterojunction compound.

According to the invention we also provide a liquid crystal comprising one or more compounds as hereinbefore described.

The compounds of the invention may be made by methods known per se. Preparation of discotic mesogens and the rod-shaped terphenyl have been described by, for example, Key: i) Br(CH₂)₆Br (5 eq.), K₂CO₃, KI, butanone, reflux 16 hrs; ii) Ethyl gallate, K₂CO₃, KI, butanone, reflux 16 hrs; Hi) aq. KOH, EtOH/THF (1:1), reflux 2 hrs; z^'v) aq. HC1; v) DCC, DMAP,^>TSA, CH₂Cl2, room temperature 5 days.

The mesophase behaviour of the compounds of the invention and/or their precursors may be investigated by optical polarising microscopy (OPM) and differential scanning calorimetry (DSC). The results are summarised in Table 2.

The invention will now be illustrated by way of example only and with reference to the accompanying drawings, in which Figure 1 is a representation of nematic phases of discs "N_DΪSC" and rods "Ncai ", the nematic phases are aligned to the director fi; Figure 2 is a schematic representation of the prepared mixed disc-rod mesogens; Figure 6 comprises selected photographs from a temperature scan of a contact sample of R2 (rod-shaped mesogen, top of the picture) and D1R2 (combined mesogen, bottom right of the picture) at (a) 92°C to (i) 74°C (cooling with 2°C / frame), the focus area was slightly shifted between (e) and (f) to allow the full mixing area to be viewed, all pictures were taken at the same spot and with crossed polarisers. The scaling bar represents 45 μm; and

Figure 7 comprises selected photographs from a temperature scan of a contact sample of DI (disc-shaped mesogen, bottom right of the picture) and D1R2 (combined mesogen, top left of the picture) at (a) 75°C; (b) 70°C; (c) 65°C; (d) 60°C; (e) 55°C; (c) 50°C. Note that the isotropic gap in between the two nematic phases disappears on cooling to 50°C. All pictures were taken at the same spot and with crossed polarisers. The scaling bar represents 45 μm. Detailed reaction procedures and structure analysis are provided in the examples and reaction scheme 1. A spacer was attached to 2 by means of a Williamson alkylation under standard conditions. Alkylation of 3 to ethyl gallate yielded 4, which was saponified to the free carboxylic acid under basic conditions. A DCC-mediated 5 esterification with the discotic mesogen 6 yielded the target material.

Key: f) Br(CH₂)₆Br (5 eq.), K₂CO₃, KI, butanone, reflux 16 hrs; if) Ethyl gallate,

K₂CO₃, KI, butanone, reflux 16 hrs; Hi) aq. KOH, EtOH/THF (1:1), reflux 2 hrs; zv)

aq. HC1; v) DCC, DMAP,/.TSA, CH₂C1₂, room temperature 5 days.

10

Experimental Section

1. Materials

, 15 All materials were used as purchased unless mentioned otherwise. THF has been distilled from sodium prior to use. The preparation of bromides 2 and 3 has been described before. Diazotation of pentylaniline with phenol, yielding 8, was described before, [ref] Mesogens DI and D2 have been fully described previously. [REF]

20 2. Instrumentation

Nuclear magnetic resonance (NMR) spectra were taken on a Jeol JNM-ECP 400 MHz FT-NMR spectrometer. Chemical shifts are reported in ppm relative to TMS. The 1H-NMR, ¹³C NMR and ¹⁹F NMR data refers to the figures that are shown in 25 the experimental section. In some ¹³C NMR spectra, multiple peaks are reported for because of the chemical dissimilarity of seemingly equal carbon atoms. The thermal properties were investigated using a Perkin Elmer DSC 7 differential calorimeter (DSC) in nitrogen against an indium standard. Transition temperatures were determined as the onset of the maximum in the endotherm or exotherm. The mesophases were studied on an Olympus BH-2 optical polarising microscope, equipped with a Mettler FP82 HT hot stage and a Mettler FP90 central processor. Pictures of the mesophases were taken using a JVC digital video camera connected to a PC. Software Studio Capture, supplied by Studio86Designs was used for image capturing.

3. Synthesis of Intermediates

1c 2d 3g 4h

V , 5] 6k

^L-0-CH₂-(CH₂ 2).,_m-₂ CH₂-Br

4e Sf 6i_7i

.a 2b 3c ,,Λ~ _{n h}/⁼ _- 81 9m 10n

CH₃-(CH₂)₃-CH₂-^^N=N-^_^O-CH (CH₂)_ΓCH₂-E

Figure 8. NMR assignment for precursor mesogens.

3.1 4-(4-Pentylphenylazo)phenol

A solution of 4-pentylaniline (8.15 g) and cone. HCl (20 ml) in water (100 ml) was chilled at 0 °C and sodium nitrite (3.45 g) was added in small portions, keeping the temperature below 5 °C. After stirring for 2 hours at low temperatures the solution of the diazonium salt was slowly added to a chilled solution of phenol (4.7 g) and NaOH (2.5 g) in water (25 mL), again keeping the temperature below 5 °C. The red product separates from the solution and is filtered off. Compound 7 was purified by two crystallisations from ethanol, yielding 10.8 g of a red crystals. 1H NMR (400 MHz, CDCI₃): δ 7.85, 7.82, 7.30, 6.93 (4xdd, 8H, H5, H6, H4 and H7, resp.); 2.67 (t, 2Η, H3); 1.71-1.61, 1.42-1.30 (2xm, 6H, H2); 0.91 (t, 3H, HI). ¹³C NMR (400 MHz, CDC1₃): δ 158.76 (k); 150.42 (g); 146.67 (d); 146.12 (h); 129.11 (e); 125.04 (f); 122.47 (f); 115.97 (j); 35.78 (c); 31.41, 30.93, 22.48 (b); 13.98 (a).

3.2 Alkylation of an aromatic alcohol with α,ω-dibromoalkane

A mixture of the aromatic alcohol (1 eq.), dibromoalkane (20 eq.), K₂CO₃ (6 eq.), KI (0.5 eq.) and butanone was refluxed overnight. The mixture was allowed to cool to room temperature, the solids were filtered off and the solvent was evaporated under reduced pressure. The oily residue was precipitated in methanol (at least five times the volume) and the crude product was filtered. Purification was done by crystallisation (from acetone, acetone/ ethanol mixtures or CH₂Cl₂/hexane mixtures) or column chromatography (SiO₂, CH₂Cl₂/hexane mixtures as eluent). 1H NMR (400 MHz, CDC1₃): δ 7.85, 7.82, 7.30, 6.93 (4xdd, 8H, H5, H6, H4 and H7, resp.); 2.67 (t, 2H, H3); 1.71-1.61, 1.42-1.30 (2xm, 6H, H2); 0.91 (t, 3H, HI). ¹³C NMR (400 MHz, CDC1₃): δ 158.76 (k); 150.42 (g); 146.67 (d); 146.12 (h); 129.11 (e); 125.04 (ι); 122.47 (f); 115.97 (j); 35.78 (c); 31.41, 30.93, 22.48 (b); 13.98 (a).

3.3 4 '-(6-BromohexyIoxy)biphenyI-4-carbonitrile

Synthesis according to the general procedure. Purification by two crystallisations from acetone :hexane . Yield: 81 % of a white powder. Thermal behaviour: K [N 61 °C (1.7 J g^"1)] 69 °C (73.7 J g^_1) I. 1H NMR (400 MHz, CDC1₃): δ 7.66, 7.61, 7.51, 6.97 (4xdd, 8H, HI, H2, H3 and H4, resp.); 3.99 (t, 2H, H5); 3.40 (t, 2H, H7); 1.92- 1.78, 1.66-1.57 (2xm, H6). ^I C NMR (400 MHz, CDC1₃): δ 159.64 (z); 145.18 (e); 132.51 (c); 131.28 ( ); 128.28 (g); 127.02 (d); 119.06 (a); 115.01 (h); 109.99 (b); 67.83 (j); 32.60 (I); 33.75, 28.98, 27.85, 25.23 (lc).

3.4 4'-(10-Bromodecyloxy)biphenyl-4-carbonitrile

Synthesis according to the general procedure. Purification by crystallisation from acetone:MeOH and CH₂C_₂:hexane. Yield: % of a white powder. Thermal behaviour: K [N 61 °C (1.7 J g^'1)] 69 °C (73.7 J g^'1) I. 1H NMR (400 MHz, CDC1₃): δ 7.66, 7.61, 7.51, 6.97 (4xdd, 8H, HI, H2, H3 and H4, resp.); 3.99 (t, 2H, H5); 3.40 (t, 2H, H7); 1.92-1.78, 1.66-1.57 (2xm, H6). ¹³C NMR (400 MHz, CDC1₃): δ 159.64 (f); 145.18 (e); 132.51 (c); 131.28 (f); 128.28 (g); 127.02 (d); 119.06 (α); 115.01 (h); 109.99 (b); 67.83 (j); 32.60 (/); 33.75, 28.98, 27.85, 25.23 (k).

3.5 4-(6-Bromohexyloxy)phenyl-(4-pentylphenyl)diazene

Synthesis according to the general procedure. Purification by crystallisation from MeOH:acetone. Yield: 74 % of yellow-orange crystals. Thermal behaviour: K 65 °C (66.4 J g ¹) SmA 79 °C (7.7 J g^"1) N 84 °C (2.8 J g ¹) I. 1H NMR (400 MHz, CDCI₃): δ 7.89, 7.77, 7.29, 6.97 (4xdd, 8H, H5, H6, H4 and H7, resp.); 4.02 (t, 2H, H8); 3.42 (t, 2H, H10); 2.65 (t, 2H, H3); 1.91-1.25 (m, 14H, H2 and HP); 0.91 (t, 3Η, HI). ¹³C NMR (400 MHz, CDC1₃): δ 161.32 (k); 150.98 (g); 146.95 (d); 145.81 (h); 129.02 (e); 124.55 (-); 122.49 (/); 114.62 j); 68.01 (I); 35.80 (c); 32.63 (n); 33.75, 29.00, 27.89, 25.26 (m); 31.44, 30.99, 22.51 (b); 14.01 (α).

3.6 4-(6-BromohexyIo--y)-2,3-difluoro-4"-octyloxy-[l,l ';4',1 ^M]terphenyl

Synthesis according to the general procedure. Purification using crystallisations from MeOH:CH₂Cl₂ and toluene:hexane. Yield: 45 % of a white powder. Thermal behaviour: K 110 °C (97 J g ¹) SmC 137 °C (0.1 J g^"1) SmA 172 °C (9.7 J g^"1) I. 1H NMR (400 MHz, CDC1₃): δ 7.62, 7.58, 56, 6.99 (4xdd, 8H, H7, H5, H6 and H4, resp.); 7.14, 6.82 (2xtd, 2H, H8 and HP); 4.10, 4.01, 3.45 (3xt, 6Η, HI0, H3 and HI 2, resp.); 1.98-1.25 (m, 20H, H2 and HI I); 0.90 (t, 3H, HI). ¹³C NMR (400 MHz, CDCI₃): δ 158.89 (d); 149.03 (q); 147.66 (o); 141,84 (p); 140.15 (h); 133.12 (k); 132.81 (g); 129.02 (j); 128.03 (i); 126.76 (f); 12 Al (m); 122.78 (I); 114.83 (e); 109.61 (n); 69.63 (r); 68.10 (c); 32.62 (t); 33.76, 31.81, 29.36, 29.28, 29.24, 28.99, 27.84, 26.06, 25.14, 22.65 (b and s) 14.10 (α). ¹⁹F NMR (400 MHz, CDC1₃): δ - 141.51 (d, i³J(F,F)| = 22 Hz); -158.69 (d, |³J(F,F)| = 22 Hz). Example 4

Preparation rod-shaped mesogen molecules

4.1 Alkylation of ethyl gallate with ω-bromoalkyl-substituted mesogens

A mixture of ethyl gallate (1 eq.), ω-bromoalkyl-substituted mesogen (4 eq.; 3 eq. for R3), K₂CO3 (6 eq.), KI (0.5 eq.) and butanone was refluxed overnight. The mixture was allowed to cool to room temperature, the solids were filtered off, washed thoroughly with warm acetone or toluene and the solvent was evaporated under reduced pressure. The residue was diluted with some CH₂CI₂ and precipitated in methanol (at least five times the volume) and the product (and excess starting material) was filtered. Purification was done by multiple crystallisations (from acetone, acetone/methanol mixtures or CH₂C_₂/hexane mixtures) or column chromatography (Siθ2, CTbC^/he ane mixtures as eluent).

Figure 9. NMR assignment for linked cyanobiphenyl mesogens.

4.2 3,4,5-tris[6-(4'-cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid ethyl ester

Synthesis according to the general procedure. Purification using column chromatography (SiO₂, eluent CH₂Cl₂:hexane (1:1) to CH₂C1₂). Yield: 81 % of a white powder. 1H NMR (400 MHz, CDCI3): δ 7.68-7.57 and 7.53-7.45 (2xm, 18H,

H1-H3); 7.27 (s, 2H, H8); 6.97-6.92 (m, 6H, H4); 4.35 (q, 2H, HI4); 4.04, 4.03, 3.99 and 3.97 (4xt, 12H, H7 and H5); 1.91-1.73 and 1.64-1.50 (2xm, 24H, H6); 1.38 (t, 3H, HIS). ¹³C NMR (400 MHz, CDC1₃): δ 166.35 0); 159.66 (i); 152.68 («); 145.14, 145.09 (e); 142.05 (m); 132.51 (c); 131.25, 131.22 (j); 128.28, 128.25 (g); 126.99,^' 126.98 (d); 125.21 (p); 119.05, 119.02 (a); 115.01, 114.98 (h); 110.02 (b); 107.93 (o); 73.20 (/); 68.92 (O; 67.99, 67.91 j); 61.02 (z); 30.19, 29.22, 29.19, 29.16, 25.89, 25.85, 25.79 (k); 14.38 (aa).

4.3 3,4,5-tris[10-(4'-cyanobip-ιenyl-4-yloxy)decyIoxy]benzoic acid ethyl ester

Synthesis according to the general procedure. Purification by crystallisation from MeOH:CH₂Cl₂ and acetone. Yield: 96 % of a white powder. 1H NMR (400 MHz, CDCI3): δ 7.68-7.58 and 7.52-7.45 (2xm, 18H, H1-H3); 7.24 (s, 2H, H8); 6.98-6.94 (m, 6Η, H4); 4.33 (q, 2H, HI4); 4.02, 4.01, 3.97 and 3.96 (4xt, 12H, H7 and H5); 1.91-1.25 (m, 48H, H6); 1.37 (t, 3H, HIS). ¹³C NMR (400 MHz, CDC1₃): δ 166.44 (y); 159.75 (/); 152.74 (n); 145.22, 145.19 (β); 142.18 (m); 132.53 (c); 131.22 (J); 128.27 (g); 127.02 (d); 125.07 (p); 119.08 (a); 115.03 (h); 110.01 (b); 107.91 (o); 73.40 (/); 69.10 (/^*); 68.10 ( ); 60.98 (z); 30.28-25.99 (/), 14.39 (aa).

4.4 3,4-bis[6-(4'-cyanobiphenyl-4-yIoxy)hexyloxy]benzoic acid ethyl ester

Figure 10. NMR assignment for linked cyanobiphenyl mesogens.

Synthesis according to the general procedure. Purification by crystallisation from butanone. Yield: 93 % of a white powder. 1H NMR (400 MHz, CDC1₃): δ 7.70-7.59 (m, 9H, HI, H2 and H8); 7.55-7.48 (m, 5H, H3 and HP); 6.98 (dd, 4Η, H4); 6.86 (dd, 1H, HI0); 4.33 (q, 2H, HI4); 4.04, 4.03 and 3.99 (3xt, 12H, H7 and HS); 1.90- 1.75 and 1.53-1.28 (2xm, 32H, H6); 1.35 (t, 3H, HIS). ¹³C NMR (400 MHz, CDC1₃): δ 166.53 (y); 159.77 (f); 153.03 (n); 148.43 (m); 145.25 (e); 132.55 (c); 131.25 (/); 128.30 (g); 127.04 (-/); 123.43 (o); 122.78 (q); 119.09 (a); 115.05 (h); 114.23 ?); 111.87 (r) 110.25 (b); 69.22, 68.95 (-); 68.12 (/^'); 60.70 (z); 29.48-29.95 and 26.02- 25.93 (k, kj, 14.39 (aa).

4.5 3,4,5-tris[6-(4-(4-pentylphenylazo)phenoxy)decyloxy]benzoic acid ethyl ester

Figure 11. NMR assignment for linked azobenzene mesogens.

Synthesis according to the general procedure. Purification by multiple crystallisations from acetone and CH₂C1₂ :hexane mixtures. Yield: 62 % of a yellow-orange powder. 1H NMR (400 MHz, CDC1₃): δ 7.88-7.72 (m, 12H, HS and H6); 7.29-7.21 (m, 8H, H4 and HIT); 6.98-6.89 (m, 6H, H7); 4.33 (t, 2H, HI2); 4.05-3.92 (m, 12H, H8 and H14); 2.64 (t, 6H, H3); 1.91-1.25 (m, 42H, H2 and HP); 1.37 (t, 3Η, HIS); 0.88 (t, 3H, HI). ¹³C NMR (400 MHz, CDC1₃): δ 166.45 (y); 161.42, 161.40 (Jc); 152.76 (p); 151.02 (g); 146.97, 146.94 (d); 145,82, 145.80 (h); 142.16 (0); 129.05 (e); 125.26 (q); 124.61 (/); 122.54 (f); 114.68 (7); 108.01 (r); 73.70 («); 68.99 (/. '); 68.23, 68.13 (I); 61.08 (2); 35.84 (c); 29.26, 29.21, 25.92, 25.84 (m); 31.50, 31.03, 22.56 (b); 14.45 (α ); 14.08 ( ). 4.6 3,4,5-tris[6-(2,3-difluoro-4"-octyIoxy-[l,l';4^,,l^M]terphenyl-4- yIoxy)hexyloxy]benzoic acid ethyl ester

Figure 12. NMR assignment for linked terphenyl mesogens.

Synthesis according to the general procedure. Purification by column chromatography (Siθ₂, eluent toluene:hexane (3:1) to toluene.-acetone (95:1) and crystallisation from MeOH:CH₂Cl₂. Yield: 46 % of a white powder. 1H NMR (400 MHz, CDC1₃): δ 7.64, 7.45 (m, 18H, H7, HS and H6); 7.24 (s, 2H, HI 3); 7.22-7.07 (m, 3H, H8); 6.98-6.92 (m, 6H, H4) 6.68-6.80 (m, 3H, HP); 4.36 (q, 2Η, HI4); 4.10- 3.95 (2xm, 18H, HI0, H3 and H12); 1.98-1.25 (m, 60H, H2 and HII); 1.35 (t, 3H, HIS); 0.89 (t, 9H, HI). ¹³C NMR (400 MHz, CDC1₃): δ 166.40 (y); 158.88 (d); 152.33 (v); 148.92 (q); 147.76 (o); 141.79 (p); 142.12 (u); 140.05, 140.00 (h); 133.10 (k); 132.76, 172.73 (g); 129.01, 128.99 (j); 128.00 (i); 126.71, 126.68 (f); 125.23 (w); 123.45 (m); 122.64, 122.54 (I); 114.81 (e); 109.54, 109.51 (n); 107.95 (x); 73.27 (t); 69.72, 69.66 (r); 68.95 (f); 68.08 (c); 61.02 (z); 31.82-22.67 (b and s) 14.41 (αα); 14.10 (α). ¹⁹F NMR (400 MHz, CDC1₃): δ -141.60 (d, |³J(F,F)| = 22 Hz); -158.66 (d, |³J(F,F)| = 22 Hz).

Example 5

Preparation mixed disc-rod molecules

5.1 Esterification reaction of the linked rod-shaped mesogens with the discshaped mesogens The free carboxylic acids of the linked rod-shaped mesogens R1-R5 were prepared by refluxing the corresponding ethyl esters in ethanol (50 ml) and aqueous KOH (5 ml, 4N). In case of limited solubility of the mesogen in hot ethanol, a part of the solvent was replaced by THF. The solution was refluxed until TLC indicated complete consumption of the starting material. The reaction mixture was neutralised with cone. HCl, cooled and the precipitated product was filtered from the mixture. Due to the very low solubility of these mesogens, they were not further isolated, but the products were directly used for the esterification with the disc-shaped mesogens. A mixture of the gallic acid (with two or three linked rod-shaped mesogens) (1 eq.) and the disc-shaped mesogen (1 eq., ca. 100-200 μmol), dicyclocarbodiimide (DCC, 10 eq.), dimethylaminopyridine (DMAP, 0.5 eq.) and p αrα-toluene sulphonic acid (pTSA, 0.5 eq.) in CH₂C1₂ or THF (5-10 ml) was stirred for 3-8 days at room temperature under inert atmosphere. Then the solvent was removed under reduced pressure, the residue was diluted with the eluent and the mixture was directly applied to a column for chromatography (SiO₂, eluent: mixtures of C^C^ e ane or CH^C^aceton). Pure samples were obtained after further chromatography and/or crystallisations.

Figure 13. NMR assignment for linked disc-rod mesogens. X represents the gallic acid moiety with the two or three rod-shaped mesogens attached and are numbered as done before. 5.2 3,4,5-tris[6-(4'-cyanobiphenyl-4-ylo--y)hexyloxy]benzoic acid 11- [pentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester

Synthesis according to the general procedure. Purification using column chromatography (SiO₂, eluent CTbC^hexane (2:1) to CH₂CI₂) and crystallisation from MeOH:CH₂Cl₂. Yield: 36 % of a pale sticky yellow solid. 1H NMR (400 MHz, CDCI₃): δ 7.67-7.45 (m, 28H, Hl-3 and HIT); 7.25 (s, 2H, H8); 6.90-6.74 (m, 16H, H4 and H18); 4.33 (t, 2H, H14); 4.27 (t, 2H, HI 6); 4.03, 4.01, 3.98 (4xt, 12H, H7 and HS); 3.83, 3.82, 3.81 (3xs, 15H, H19); 1.92-1.25 (m, 66H, H6 and HIS). ¹³C NMR (400 MHz, CDCI3): δ 166.47 (y); 160.04, 159.92, 159.82 (al); 159.76 (ac); 159.63 (0; 152.75 (n); 145.22, 145.19 (e); 142.21 (m); 133.27, 133.13, 133.10 (aj); 132.54, 132.52 (c); 131.21, 131.17 (f); 128.40 (ac); 128.28 (g); 127.01 (d); 125.12 (p); 123.87 (qβ; 119.85 (αή; 119.11, 119.08 (a); 115.69, 115.56, 115.46 (a ); 115.02 (A); 114.12, 114.09, 114.08 (ak); 110.02, 109.96 (b); 107.95 (o); 99.20, 98.99, 96.97 (ag); 86.63, 86.08, 83.58 (ah); 74.61 (v); 73.42 (l); 69.12 (O_. 68.11, 68.07 (JJ , 65.20 (z); 55.34, 55.32 (am); 30.60-25.04 (k and αα).

5.3 3,4,5-tris[10-(4'-cyanobiphenyI-4-yloxy)decyloxy]benzoic acid 11- [pentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester

Synthesis according to the general procedure. Purification using column chromatography (SiO₂, eluent CH₂C_₂:hexane (2:1) to CH2CI2) and crystallisation from MeOH:CH₂Cl₂. Yield: 36 % of a pale sticky yellow solid. 1H NMR (400 MHz, CDC1₃): δ 7.67-7.45 (m, 28H, Hl-3 and HIT); 7.25 (s, 2H, HS); 6.90-6.74 (m, 16Η, H4 and H18); 4.33 (t, 2H, HI4); 4.27 (t, 2H, H16); 4.03, 4.01, 3.98 (4xt, 12H, H7 and HS); 3.83, 3.82, 3.81 (3xs, 15H, HI9); 1.92-1.25 (m, 66H, H6 and HIS). ¹³C NMR (400 MHz, CDCI₃): δ 166.47 (y); 160.04, 159.92, 159.82 (al); 159.76 (ac); 159.63 (i); 152.75 (n); 145.22, 145.19 (e); 142.21 (m); 133.27, 133.13, 133.10 (α/); 132.54, 132.52 (c); 131.21, 131.17 (j) 128.40 ( c); 128.28 fe); 127.01 (d); 125.12 (p); 123.87 (af); 119.85 H; 119.11, 119.08 (a); 115.69, 115.56, 115.46 (af); 115.02 (A); 114.12, 114.09, 114.08 (ak); 110.02, 109.96 (b); 107.95 (o); 99.20, 98.99, 96.97 (ag); 86.63, 86.08, 83.58 (ah); 74.61 (v); 73.42 (I); 69.12 (I , 68.11, 68.07 (j, jy, 65.20 (-.); 55.34, 55.32 (am); 30.60-25.04 (£and -.-z).

5.4 3,4,5-tris[6-(4'-cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid 11- [pentakis(4-hexyloxyphenyletynyl)phenoxy] undecyl ester

Synthesis according to the general procedure. Purification using column chromatography (Siθ₂, eluent EtOAc:hexane (3:2)) and crystallisation from MeOH:CH₂Cl₂. Yield: 41 % of a pale yellow powder. 1H NMR (400 MHz, CDC1₃): δ 7.65-7.39 (m, 28H, Hl-3 and HIT); 7.25 (s, 2H, HS); 6.88-6.75 (m, 16Η, H4 and H18); 4.30 (t, 2H, H14); 4.27 (t, 2H, H16); 4.01 (t, 12H, HT) 3.98-3.91 (m, 16H, H5 and H19); 1.92-1.25 (m, 82H, H6, HIS and H20); 0.85-0.94 (m, 15H, H21). ¹³C NMR (400 MHz, CDCI₃): δ 166.38 (y); 159.85 (ac); 159.66, 159.51, 159.45 (al); 159.63 (z); 152.69 («); 145.14, 145.09 (e); 142.06 (m); 133.24, 133.10, 133.06 (af); 132.51 (c); 131.19 (/); 128.37 (ac); 128.26 fe); 126.98 (d); 125.25 (/?); 123.87 (α ); 119.80 (ad); 119.06, 119.02 ( ); 115.21, 115.14, 115.10 (af); 114.98 (h); 114.61, 114.59, 114.58 (α/c); 110.02, 109.97 (b); 107.92 (o); 99.31, 99.08, 97.08 (ag); 86.60, 86.06, 83.55 (ah); 74.55 (z); 73.22 (I); 68.94 (/"); 68.09 (am); 67.99, 67.90 (/); 65.23 (z); 31.58-22.58 (£, αα and an); 14.02 (αo).

5.5 3,4,5-tris[10-(4'-cyanobiphenyl-4-yloxy)decyloxy]benzoic acid 11- [pentakis(4-hexyloxyphenyletynyl)phenoxy] undecyl ester

Synthesis according to the general procedure. Purification using column chromatography (Siθ₂, eluent EtOAc:hexane (3:2) to EtOAc.hexane (3:1)) and crystallisation from CH₂Cl₂:hexane. Yield: 42 % of a pale yellow powder. 1H NMR (400 MHz, CDC1₃): δ 7.68-7.59 ( , 9H, HI, H2 and H8); 7.57-7.44 (m, 15H, H3, H9 and HIT); 6.94 (dd, 4H, H4); 6.86-6.73 (m, 11H, H10 and HI 8); 4.35 (t, 2H, H16); 4.27 (t, 2H, H14); 4.04, 4.03, 3.99 and 3.97 (4xt, 12H, H7 and HS); 3.85-3.84 (3xs, 15H,^'HiP); 1.92-1.25 (m, 50Η, H6 and HIS). ¹ C NMR (400 MHz, CDC1₃): δ 166.56 (z); 159.99, 159.89, 159.80 (αϊ); 159.85 (αc); 159.73 (i); 153.00 (n); 148.38 (m); 145.20 (e); 133.24, 133.10, 133.07 (aj); 132.51 (c); 131.18, 131.14 (f); 128.37 (ac); 128.25 (g); 126.99 (d); 123.82 («/); 123.38 (p); 122.77 (q); 119.83 (Ω ); 119.07 (a); 115.69, 115.53, 115.45 (αz); 115.00 (h); 114.22 (o); 114.09, 114.05 (ak); 111.85 (r); 109.97, 109.93 (b); 99.15, 98.98, 96.91 (ag); 86.60, 86.27, 83.54 (ah); 74.60 (ab); 69.18, 68.92 (I) 68.08 ( ); 67.90 (z); 55.30, 55.28 (am); 30.56-25.90 (/c and aa).

5.6 3,4-bis[10-(4'-cyanobiphenyl-4-yloxy)decyloxy]benzoic acid 11-

[pentakis(4-methoxyphenyIetynyl)phenoxy] undecyl ester

Synthesis according to the general procedure. Purification using column chromatography (Siθ , eluent EtOAc:hexane (3:2) to EtOAc:hexane (3:1)) and crystallisation from CH₂Cl₂:hexane. Yield: 42 % of a pale yellow powder. 1H NMR (400 MHz, CDC1₃): δ 7.68-7.59 (m, 9H, HI, H2 and H8); 7.57-7 '.44 (m, 15H, H3, H9 and HI 7); 6.94 (dd, 4H, H4); 6.86-6.73 (m, 11H, H10 and HI 8); 4.35 (t, 2H, HI 6); 4.27 (t, 2H, H14); 4.04, 4.03, 3.99 and .3.97 (4xt, 12H, H7 and HS); 3.85-3.84 (3xs, 15H, H19); 1.92-1.25 (m, 50H, H6 and HIS). ¹³C NMR (400 MHz, CDC1₃): δ 166.56 (z); 159.99, 159.89, 159.80 (al); 159.85 (ac); 159.73 (i); 153.00 (n); 148.38 (rn); 145.20 (e); 133.24, 133.10, 133.07 (aj); 132.51 (c); 131.18, 131.14 if); 128.37 (αc); 128.25 (g); 126.99 (d); 123.82 ( ); 123.38 (p); 122.77 (9); 119.83 (αtf); 119.07 (a); 115.69, 115.53, 115.45 (af); 115.00 (A); 114.22 (o); 114.09, 114.05 (ak); 111.85 (r); 109.97, 109.93 (b); 99.15, 98.98, 96.91 (ag); 86.60, 86.27, 83.54 (ah); 74.60 (ab); 69.18, 68.92 (0; 68.08 (j); 67.90 (z); 55.30, 55.28 (am); 30.56-25.90 (k d aa).

5.7 3,4,5-tris[6-(4-(4-pentyIphenyIazo)phenoxy)hexyIoxy]benzoic acid 11- [pentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester

Synthesis according to the general procedure. Purification using column chromatography (SiO₂, eluent CH-C^hexane (2:1) to CH2CI2) and crystallisation from MeOH:CH₂Cl₂. Yield: 55 % of a yellow powder. 1H NMR (400 MHz, CDCI3): δ 7.85-7.75 (m, 12H, HS and H6); 7.56-7.48 (m, 10H, HIT); 7.29-7.22 (m, 8H, H4 and Hll); 6.95-6.89 (m, 6H, H7); 6.88-6.81 (m, 10H, H18); 4.31 (t, 2H, H14); 4.25 (t, 2H, HI 6); 4.03, 4.00 (2xt, 12H, H8 and HI 0); 3.81, 3.80 (2xs, 15H, H19); 2.63 (t, 2H, H3); 1.91-1.21 (m, 60H, H2, H9 and HIS); 0.87 (t, 3H, HI). ¹³C NMR (400 MHz, CDC1₃): δ 166.32 (y); 161.22 (k); 159.89, 159.79, 159.70 (at); 159.77 (ac); 152.60 (p); 150.87 (g); 146.79, 146.76 (d); 145.62, 145.60 (h); 142.00 (σ); 133.15, 133.02, 132.99 (a/); 128.88 (e); 128.28 (αc); 125.11 (q); 124.42 (z); 123.73 (α ); 122.38 ( ); 119.74 (αd); 115.61, 115.44, 115.37 (af); 114.48 (_/); 114.00, 113.96 (af); 107.84 (r); 99.05, 98.88, 96.82 (ae); 86.51, 85.98, 83.45 (aj); 74.50 (αb); 73.15 (n); 68.83 (« ; 68.06, 67.97 (l); 65.11 (z); 55.21 (am); 35.68 (c); 31.33, 30.87, 22.40 (b); 28.60, 26.25 (m); 30.26-25.69 (aa); 13.90 (a).

Example 6

3,4,5-tris[6-(2,3-difluoro-4"-octyIoxy-[l, ;4',l"]terphenyl-4-yloxy)hexyloxy] benzoic acid ll-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester

6.1 4-(6-Bromohexyloxy)-2,3-difluoro-4 -octyloxy-[l,l';4',l"]terphenyl (3).

A mixture of the aromatic alcohol 4-hydroxy)-2,3-difluoro-4"-octyloxy- [l,l';4',l"]terphenyl (2)(1 eq.), dibromohexane (5 eq.), K₂CO₃ (5 eq.), KI (0.5 eq.) and butanone was refluxed overnight. The mixture was allowed to cool to room temperature, the solids were filtered off and the solvent was evaporated under reduced pressure. The oily residue was precipitated in methanol (at least five times the volume) and the was filtered. Pure 3 was obtained by multiple crystallisations form MeOH:CH₂Cl₂ and toluene:hexane. Yield: 45 % of a white powder. Thermal behaviour: K 110 °C (97 J g^"1) SmC 137 °C (0.1 J g ¹) SmA 172 °C (9.7 J g^"1) I.

Figure 1. NMR assignment for 3 (letters for proton assignment and numbers for carbon assignment).

1H NMR (400 MHz, CDC1₃): δ 7.62, 7.58, 56, 6.99 (4xdd, 8H, HT, H5, H6 and H4, resp.); 7.14, 6.82 (2xtd, 2H, H8 and HP); 4.10, 4.01, 3.45 (3χt, 6Η, H10, H3 and HI 2, resp.); 1.98-1.25 ( , 20H, H2 and Hll); 0.90 (t, 3H, HI). ¹³C NMR (400 MHz, CDC1₃): δ 158.89 (d); 149.03 (q); 147.66 (o); 141,84 (p); 140.15 (/.); 133.12 (k); 132.81 (g); 129.02 (/); 128.03 (f); 126.76 (f); 123.47 (m); 122.78 ( ); 114.83 (e); 109.61 (n); 69.63 (r); 68.10 (c); 32.62 (t); 33.76, 31.81, 29.36, 29.28, 29.24, 28.99, 27.84, 26.06, 25.14, 22.65 (b and s) 14.10 (a). ^I9F NMR (400 MHz, CDC1₃): δ - 141.51 (d, |³J(F,F)| = 22 Hz); -158.69 (d, |³J(F,F)| = 22 Hz).

6.2 3,4,5-Tris[6-(2,3-difluoro-4"-octyIoxy-[l,l';4',l^M]terphenyI-4- yloxy)hexyloxy]benzoic acid ethyl ester (4).

Synthesis according to the general procedure. A mixture of ethyl gallate (1 eq.), bromide 3 (4 eq.), K₂CO₃ (6 eq.), KI (0.5 eq.) and butanone was refluxed overnight. The mixture was allowed to cool to room temperature, the solids were filtered off, washed thoroughly with warm acetone and toluene and the solvent was evaporated under reduced pressure. The residue was diluted with some CH₂C1₂ and precipitated in methanol (at least five times the volume) and the product (and excess starting material) was filtered. Trimer 4 was purified by column chromatography (SiO₂, eluent toluene:hexane (3:1) to toluene:acetone (95:5) and crystallisation from MeOH:CH₂Cl₂ (2x). Yield: 46 % of a white powder.

Figure 2. NMR assignment for 4 (letters for proton assignment and numbers for carbon assignment).

1H NMR (400 MHz, CDC1₃): δ 7.64, 7.45 (m, 18H, HT, HS and H6); 7.24 (s, 2H, HI 3); 7.22-7.07 (m, 3H, H8); 6.98-6.92 (m, 6H, H4) 6.68-6.80 (m, 3H, HP); 4.36 (q, 2Η, H14); 4.10-3.95 (2xm, 18H, H10, H3 and H12); 1.98-1.25 (m, 60H, H2 and Hll); 1.35 (t, 3H, HIS); 0.89 (t, 9H, HI). ¹³C NMR (400 MHz, CDCI₃): δ 166.40 (y); 158.88 (d); 152.33 (v); 148.92 (q); 147.76 (o); 141.79 (p); 142.12 (u); 140.05, 140.00 (h); 133.10 (k); 132.76, 172.73 (g); 129.01, 128.99 (j); 128.00 (z); 126.71, 126.68 (f); 125.23 (w); 123.45 (m); 122.64, 122.54 (I); 73.27 (t); 69.72, 69.66 (r); 68.95 (t'); 68.08 (c); 61.02 (z); 31.82-22.67 (b and s) 14.41 (α ); 14.10 (α). ¹⁹F NMR (400 MHz, CDC1₃): δ -141.60 (d, |³J(F,F)| = 22 Hz); -158.66 (d, |³J(F,F)| = 22 Hz).

6.2 3,4,5-tris[6-(2,3-difluoro-4^M-octyloxy-[l,l';4',l"]terphenyl-4- yloxy)hexyloxy]benzoic acid ll-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester (1)

The free carboxylic acids of the trimer 4 was prepared by refluxing the corresponding ethyl esters in ethanol/THF (25+25 mL) and aqueous KOH (5 mL, 4N). The solution was refluxed until TLC indicated complete consumption of the starting material (ca. 2 hrs). The reaction mixture was neutralised with cone. HCl, cooled and the precipitated product was filtered from the mixture. Due to the very low solubility of 5, the material was not isolated, but the product was directly used for the esterification with the disc-shaped mesogen 6.

A mixture of the disc-shaped mesogen (1 eq., 100 μmol), the gallic acid derivative 5 (1 eq.) and dicyclocarbodiimide (DCC, 10 eq.), dimethylaminopyridine (DMAP, 0.5 eq.) and p αra-toluene sulphonic acid (pTSA, 0.5 eq.) in CH₂CI₂ or THF (5-10 mL) was stirred for 5 days at room temperature under inert atmosphere. Then the solvent was removed under reduced pressure, the residue was diluted with the eluent and the mixture was directly applied to a column for chromatography (SiO₂, eluent toluene :CH₂Cl₂ (1:2)). Pure samples were obtained after further chromatography (SiO₂, eluent CH₂C1₂) and crystallisations from MeOH:CH₂Cl₂. Yield: 39 % of a yellow powder.

1H NMR (400 MHz, CDCI3): δ 7.58-7.46 (m, 28H, H5, H6, HT and HIT); 7.25 (s, 2H, HIS) 7.10-7.01 (m, 3H, HS); 6.97-6.92 (m, 6Η, H4); 6.90-6.85 (m, 10H, Hlδ);

6.11-6.69 (m, 3H, HP); 4.33 (t, 2Η, H14); 4.29 (t, 2H, HI 6); 4.04, 3.97 (2xt, 18H,

H3, H10 and H12); 3.83, 3.82, 3.80 (3xs, 15H, H19); 1.95-1.23 (m, 78H, H2, Hll and HI 5); 0.89 (t, 3H, HI). ¹³C NMR (400 MHz, CDC1₃): δ 166.45 ( ); 160.04,

159.94, 159.90 (al); 159.84 (ac); 158.86 (d); 152.72 (v); 148.84 (q); 147.66 (o); 142.13 (u); 141.76 (p); 139.99, 139.96 (h); 133.27, 133.14, 133.11 (aj); 133.23 (k);

132.74, 172.72 (g); 129.00, 128.98 (j); 128.00 (z); 128.41 (ae); 126.68, 126.66 (j);

125.25 (w); 123.86 (af); 123.45 ( ); 122.61, 122.50 (I); 119.88 (ad); 115.72, 115.54,

115.47 (at); 114.80 (e); 114.13, 114.09 (ak); 109.46 (n); 107.95 (x); 99.22, 99.05,

96.98 (ag); 86.64, 86.11, 83.58 (ah); 74.62 (ab); 73.28 (t); 69.70, 69.63 (r); 68.95 (t ; 68.08 (c); 65.24 (z); 55.33, 55.31 (am); 31.83-22.66 (b, s and aa); 14.11 (a). ¹⁹F

NMR (400 MHz, CDC1₃): δ -141.62 to -142.72 (m); -158.69 to -158.82 (m). Example 7

Materials

The combined mesogens are constituted form disc-shaped mesogens, based on a pentakis(phenylethynyl)phenyl ether cores (DI and D2, see Figure 3) and rod-shaped mesogens, based on cyanobiphenyl (R1-R3), azobenzene (R4) or terphenyl (R5) cores (see Figure 4). The two discotic mesogens vary by the length of the five tails around the aromatic core. Two or three rod-shaped mesogens are linked by gallic acid moiety via a flexible spacer (m = 6 or 10). It is anticipated that the use of other rod- shaped mesogens with nematic tendencies will give similar results.

Figure 3. Structure of the disc-shaped mesogens.

Example 8

Phase behaviour mesogens

The liquid crystalline properties of the disc-rod mesogens and their precursors were determined by optical polarising microscopy (OPM) and differential scanning calorimetry (DSC). The results are summarised in Table 1.

Example 9

Mixing studies Mixing studies of the disc-rod mesogens were mixed with both precursors were performed to establish the mesomorphic behaviour over the entire disc-rod composition range. Using optical microscopy contact samples between two samples were studied. In general, linear mixing behaviour was observed between the nematic phase of the rod-disc mesogen and the corresponding rod-shaped precursors, e.g. D1R2 with R2, D1R3 with D3 and D1R4 with R4. Mixtures of the disc-rod mesogens with the discs, however, showed more complex mixing behaviour. In all contact samples, a minimum in the nematic-isotropic phase transition temperature JNI was observed. Upon cooling the contact sample, the nematic phases from both components grew towards each other and when the both nematic phases 'met' (when the isotropic interface disappeared), a nematic texture is observed over the full composition range (as long as the pure compounds did not crystallise yet). It is noted that at first, the texture is very small, but after some annealing, typically for 1 hour just below the mimmum JN_I. the domains have grown considerably and a homogeneous nematic texture is obtained. This indicates full miscibility between the two nematic phases. Figures 6 and 7 show a series of photographs taken from contact samples.

References

(1) De Gennes, P.G.; Prost, J. in The Physics of Liquid Crystals, Clarendon Press, Oxford, 1993.

(2) (a) Fletcher, I.D.; Luckhurst, G.R. Liq. Cryst. 1995, 18, 175-183. (b) Hunt, J.J.; Date, R.W.; Timimi, B.A.; Luckhurst, G.R.; Bruce, D.W. J. Am. Chem. Soc. 2001, i-25, 10115-10116

(3) Kouwer, P.H.J.; Jager, W.F.; Mijs, W.J.; Picken, S.J. Macromolecules 2001, 34, 7582-7584. (b) Kouwer, P.H.J.; Jager, .F.; Mijs, W.J.; Picken, S.J. J. Mater. Chem., submitted for publication .

I 01433 O.2

Claims

Claims

1. A compound which is a liquid crystal which comprises a discotic nematic phase promoting moiety and at least two calamitic nematic phase promoting moieties.

2. A compound according to claim 1 characterised in that the discotic nematic phase promoting moiety comprises a disc shaped moiety.

3. A compound according to claim 2 characterised in that each of the at least two calamitic nematic phase promoting moieties comprise rod shaped moieties.

4. A compound according to claim 1 which comprises a compound of formula I comprising a disc-shaped mesogen and a rod-shaped mesogen;

in which R is X or hydrogen or is represented by formula II provided that at least one group is represented by formula II;

Formula II

wherein Di is selected from the following rings or fused ring systems:

each of which may optionally be substituted in at least one of the available positions with one or more of a substituent selected from the group F, CI, Br, CN, NO₂, Li,

OL₂ and SL₃;

Ei is selected from the group; single bond, -CO₂- -OCO-, -CH₂CH₂- -CH=CH-

-C-≡C-, -CH₂O~, -OCH2-, -CH₂S-, -SCH₂-, -CN=N- -N=CH- -N=N-

OCO(CH₂)c and CO₂(CH₂)_c; Yi is selected from the group; single bond, O, S, CH₂, CO₂, OCO, CONH, NHCO,

NH and-(C=O)-;

Ti is selected from the group; H, CN, F, CI, CF₃, NO₂, NCS, SCN, L₄, OL₅, SL₆,

CO₂L₇, OCOL_8;

X is represented by formula III;

rod-shaped

-[Y₂]-Q—[Y₃h-[Z]- -Q₂ mesogen

Formula III

wherein [Z], which is a bond or is optionally a branching group, provided that when it is not a branching group then at least one R group in formula I is a group X, and when [Z] is a branching group it is selected from Ei or is an aromatic or aliphatic multifunctional moiety, selected from one of the structures of formula V;

Formula V Substitution may be on any available position.

[Y₂], [Y3] and [Y₄], which may be the same or different, are each selected from the group; single bond, H, O, S, CH₂, CO₂, OCO, CONH, NHCO, NH, -(C=O)-, CH₂O,

CH₂CH₂O, CH₂OCO, CH₂CH₂OCO;

Qi and Q₂, which may be the same or different, are each selected from the group;

(CH₂)_g, (CF₂)_h, (CH₂CH₂O)iCH₂CH₂ and (SiZ^O^SiZ², , Z¹ and Z², which may be the same or different, are each selected from CH₃, CF3 and

H;

Li, L₂ and L₃, which may be the same or different, are each a Cι_₅ branched or straight alkyl chain;

L₄, L5, L₆, ₇ and L₈, which may be the same or different, are each a Cue straight or branched alkyl chain; c is an integer from 1 to 12; g and h, which may be the same or different, are each an integer from 1 to 20; i andj, which may be the same or different, are each an integer from 1 to 10; and m is an integer from 1 to 5.

5. A compound according- to claim 4 characterised in that the rod-shaped mesogen is selected from an end-on rod-shaped mesogen or a side on rod-shaped mesogen.

6. A compound according to claim 5 characterised in that the rod-shaped mesogen is an end-on rod-shaped mesogen of formula IV;

wherein D₂, D₃ and D , which may be the same or different, are each selected from the following groups;

each of which may optionally be substituted in at least one of the available positions with one or more of the following substituents: F, CI, Br, CN, NO₂, L , OLι₀ and

SL_lι;

E₂ and E₃, which may be the same or different, are each selected from the group; single bond, -CO₂- -QCO-, -CH₂CH₂- -CH=CH- -C≡C-, -CH₂O-, -OCH₂- -CH₂S- -SCH₂- -CN=N- -N=CH- -N=N- OCO(CH₂)_f and

CO₂(CH₂)_f ;

T₂ is selected from the group; H, CN, F, CI, CF₃, NO₂, NCS, SCN, L_i2, OL13, SL_M,

CO2L15 and OCOLie,

L₉, Lio and Ln, which may be the same or different, are each selected from a Cι_₅ branched or straight alkyl chain; L12, L13, L_i4, L15 and Lι₆, which may be the same or different, are each a Cl-16 straight or branched alkyl chain; and f is an integer from 1 to 4.

7. A compound according to claim 5 characterised in that the rod-shaped mesogen is a side-on on rod-shaped mesogen of formula INa;

wherein D₂, D3, D₄ and D₅, which may be the same or different, are each selected from the following groups;

each of which may optionally be substituted in at least one of the available positions with one or more of the following substituents: F, CI, Br, CN, NO2, L₉, OLio and

SLπ;

E₂, E₃ and E₄, which may be the same or different, are each selected from the group; single bond, -CO₂- -OCO- -CH₂CH₂- -CH=CH- -C=C-

-CH₂O-, -OCH₂- -CH₂S- -SCH2-, -CN=N- -N=CH- -N=N- OCO(CH₂)_f and CO₂(CH₂)_f ;

T₂ and T₃, which may be the same or different, are each selected from the group; H,

CN, F, CI, CF₃, NO , NCS, SCN, L_]2, OL₁₃, SLι₄, CO₂Lι₅ and OCOLι₆,

L₉, Lio and Ln, which may be the same or different, are each selected from a C₁-₅ branched or straight alkyl chain; L₁₂, L₁₃, Lι , L₁5 and Lι₆, which may be the same or different, are each a Cl-16 straight or branched alkyl chain; and f is an integer from 1 to 4.

8. A compound according to claim 7 characterised in that the groups D₃ or D₅ are substituted by a spacer of type Q in one of the available positions.

5

9. A compound according to claim 6 characterised in that Ti includes one or more non-adjacent CH₂ groups that are substituted with CH(CN), CH(CF3), CH(C1) CH(CH₃) in chiral or non-chiral form and/or one or more non-adjacent CH₂ groups that are substituted by CH such that there is a double bond present and the terminal

10 CH₃ group may be replaced by a CH₂ group.

10. A compound according to claim 2 or 4 characterised in that the disc-shaped mesogen is ll-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl alcohol or 11- [pentakis(4-hexyloxyphenyletynyl)phenoxy] undecyl alcohol.

15 il. A compound according to 4 characterised in that the compound is a compound of formula X;

so^¬ in which Rx is selected from one of the following;

5 in which m is an integer from 6 to 10.

12. A compound according to claim 3 or 4 characterised in that the rod-shaped mesogen is selected from the group comprising; 3,4,5-tris[6-(4'-cyanobiphenyl-4- yloxy)hexyloxy]benzoic acid ethyl ester; 3,4,5-tris[10-(4'-cyanobiphenyl-4- 0.-._ ,yloxy)decyl xylbenzoic acid ethyl ester; 3,4-bis[6-(4'-cyanobiphenyl-4- yloxy)hexyloxy]benzoic acid ethyl . ester; 3,4,5-tris[6-(4-(4- ρentylphenylazo)ρhenoxy)decyloxy]benzoic acid ethyl ester; and 3,4,5-tris[6-(2,3- difluoro-4"-octyloxy-[l, ;4',l"]terphenyl-4-yloxy)hexyloxy]benzoic acid ethyl ester.

13. A compound according to claim 4 characterised in that the compound comprises an ester formed between ll-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl alcohol or l l-[ρentakis(4-hexyloxyphenyletynyl)phenoxy] undecyl alcohol and a compound selected from the group comprising; 3,4,5-tris[6-(4'-cyanobiphenyl- 4-yloxy)hexyloxy]benzoic acid; 3,4,5-tris[10-(4'-cyanobiphenyl-4- yloxy)decyloxy]benzoic acid; 3,4-bis[6-(4'-cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid; 3,4,5-tris[6-(4-(4-pentylphenylazo)phenoxy)decyloxy]benzoic acid; and 3,4,5- tris[6-(2,3-difluoro-4"-octyloxy~[l, ;4',r^,]terphenyl-4-yloxy)hexyloxy]benzoic acid.

14. A compound according to claim 13 characterised in that the compound is selected from the group consisting of 3,4,5-tris[6-(4'-cyanobiphenyl-4- yloxy)hexyloxy]benzoic acid l l-[pent-Lkis(4-methoxyphenyletynyl)phenoxy] undecyl ester; 3,4,5-tris[10-(4'-cyanobiphenyl-4-yloxy)decyloxy]benzoic acid ll-[pentakis(4- methoxyphenyletynyl)phenoxy] undecyl ester; 3,4,5-tris[6-(4'-cyanobiphenyl-4- yloxy)hexyloxy]benzoic acid 1 l-[pentakis(4-hexyloxyphenyletynyl)phenoxy] undecyl ester; 3,4,5-tris[10-(4'-cyanobiphenyl-4-yloxy)decyloxy]benzoic acid 11- [pentakis(4-hexyloxyphenyletynyl)phenoxy] undecyl ester; 3,4-bis[10-(4'- cyanobiphenyl-4-yloxy)decyloxy]benzoic acid 1 l-[pentakis(4-methoxyphenyIetynyl)- phenoxy] undecyl ester; 3,4,5-tris[6-(4-(4- pentylphenylazo)phenoxy)hexyloxy]benzoic acid 1 l-[pentakis(4-methoxy- phenyletynyl)phenoxy] undecyl ester; and 3,4,5-tris[6-(2,3-difluoro-4"-octyloxy- [l,r;4',l"]terphenyl-4-yloxy)hexyloxy]benzoic acid ll-[pentakis(4- methoxyphenyletynyl)phenoxy] undecyl ester.

15. A compound according to claim 14 characterised in that the compound is a compound of formula D1R5, 3,4,5-tris[6-(2,3-difluoro-4"-octyloxy- [l,r;4',l"]terphenyl-4-loxy)hexyloxy]benzoic acid ll-[pentakis(4- methoxyphenyletynyl)phenoxy] undecyl ester.

16. A compound according to claim 4 characterised in that the compound is admixed with a rod-shaped mesogen or a disc-shaped mesogen.

17. A compound according to claim 4 characterised in that the compound is admixed with a rod-shaped mesogen and a disc-shaped mesogen.

18. A compound according to claims 8, 16 or 17 characterised in that the rod- shaped mesogen is selected from the group comprising; 3,4,5-tris[6-(4'- cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid ethyl ester; 3,4,5-tris[10-(4'- cyanobiphenyl-4-yloxy)decyloxy]benzoic acid ethyl ester; 3,4-bis[6-(4'- cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid ethyl ester; 3,4,5-tris[6-(4-(4- pentylphenylazo)ρhenoxy)decyloxy]benzoic acid ethyl ester; and 3,4,5-tris[6-(2,3- difluoro-4"-octyloxy-[l,r;4',r^,]terphenyl-4-yloxy)hexyloxy]benzoic acid ethyl ester.

19. A compound according to claims 11 or 12 characterised in that the discshaped mesogen is 3,4,5-tris[6-(4'-cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid 11- [pentakis(4-methoxyphenyletynyl)phenoxy] undecyl alcohol.

20. The use of a compound according to claim 4 in the manufacture of a liquid crystal.

21. The use of a compound according to claim 16 in the manufacture of a liquid crystal.

22. The use according to claim 21 characterised in that the mesogen is a discshaped mesogen.

23. The use according to claim 22 characterised in that the disc-shaped mesogen is 3,4,5-tris[6-(4'-cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid ll-[pentakis(4- methoxyphenyletynyl)phenoxy] undecyl alcohol.

24. The use according to claim 21 characterised in that the mesogen is a rod- shaped mesogen.

25. The use according to claim 24 characterised in that the rod-shaped mesogen is selected from the group comprising; 3,4₅5-tris[6-(4'-cyanobiphenyl-4- yloxy)hexyloxy]benzoic acid ethyl ester; 3,4,5-tris[10-(4'-cyanobiphenyl-4- yloxy)decyloxy]benzoic acid ethyl ester; 3,4-bis[6-(4'-cyanobiphenyl-4- yloxy)hexyloxy]benzoic acid ethyl ester; 3,4,5-tris[6-(4-(4- pentylphenylazo)phenoxy)decyloxy]benzoic acid ethyl ester; and 3,4,5-tris[6-(2,3- difluoro-4"-octyloxy-[l,r;4',l"]terphenyl-4-yloxy)hexyloxy]benzoic acid ethyl ester.

26. The use according to claim 25 characterised in that the compound is a compound of formula D1R5, 3,4,5-tris[6-(2,3-difluoro-4"-octyloxy- [l, ;4', ']terphenyl-4-yloxy)hexyloxy]benzoic acid l l-[pentakis(4- methoxyphenyletynyl)phenoxy] undecyl ester.

27. The use of a compound according to claim 4 in the manufacture of a liquid crystal that exhibits a nematic phase.

28. The use of a compound according to claim 27 in the manufacture of a liquid crystal that exhibits a uni-axial nematic phase.

29. The use of a compound according to claim 27 in the manufacture of a liquid crystal that exhibits a biaxial nematic phase.

30. The use of a compound according to claim 27 in the manufacture of a liquid crystal that exhibits a chiral nematic phase.

31. The use of a compound according to claim 4 in the manufacture of a liquid crystal containing discotic nematic liquid crystal components.

32. The use of a compound according to claim 4 in the manufacture of a liquid crystal containing discotic nematic and calamitic liquid crystal components.

33. The use of a liquid crystal according to claim 1 or a compound according to claim 4 in the manufacture of a transmissive or reflective device.

34. The use of a liquid crystal according to claim 1 or a compound according to claim 30 in the manufacture of transmissive or reflective devices, where the molecules are in a biaxial nematic phase.

35. The use of a compound according to claim 4 in the manufacture of a liquid crystal which exhibits a smectic A phase.

36. The use of a compound according to claim 4 in the manufacture of a liquid crystal which exhibits a smectic C phase.

37. The use of a compound according to claim 4 in the manufacture of a liquid crystal which exhibits a chiral smectic C phase

38. The use of a compound according to claim 4 in the manufacture of a liquid crystal wherein the two directors of the nematic phase can be oriented selectively and independently.

39. The use of a compound according to claim 4 in the manufacture of a liquid crystal which comprises a polymer so that one of the nematic directors of the mixture is oriented by the polymer the other can be oriented by electromagnetic fields allowing for mechanically flexible devices and for devices where a preferred orientation by a alignment of the polymer matrix; the design of very large area devices without alignment problems .

40. The use of a compound according to claim 1 in the manufacture of a device comprising two spaced cell walls, each bearing electrode structures on at least one facing surface treated with an alignment layer, a layer of liquid crystal material enclosed between the cell walls, characterised that it incorporates a liquid crystal or a liquid crystal mixtures mixture containing nematic liquid crystal.

41. The use of a compound according to claim 1 in the manufacture of a device comprising two spaced cell walls whose transparency in the electromagnetic spectrum is dissimilar, at least one bearing electrode structures on at least one facing surface treated with an alignment layer, a layer of liquid crystal material enclosed between the cell walls, characterised that it incorporates a liquid crystal or a hquid crystal mixtures mixture containing nematic liquid crystal.

42. The use of a compound according to claim 1 in the manufacture of a data storage, memory, or 3D memory device and/or data and processing systems of which optical or holographic devices are examples.

43. The use of a compound according to claim 1 in the manufacture of a laser, where the wavelength of the emitted radiation can be varied by the variation of the pitch of the cholesteric helix performed by the appUcation of an electric field or temperature, or where cholesteric elastomers are used by the application of a mechanical field or temperature.

44. The use of a compound according to claim 1 in the manufacture of a data transmission device.

45. The use of a compound according to claim 1 in the manufacture of an optical switch.

46. The use of a compound according to claim 1 in the manufacture of an optical data transmission device for the alignment of the liquid crystal mixtures.

47. The use of a compound according to claim 1 in the manufacture of a laser.

48. The use of a compound according to claim 1 in the manufacture of an opto- electrical switch.

49. The use of a compound according to claim 1 in the manufacture of an optical computing system.

50. The use of a compound according to claim 1 in the manufacture of a component in protective devices for radiation.

51. The use of a compound according to claim 1 in the manufacture of a paint.

52. The use of a compound according to claim 1 in the manufacture of a medical diagnostic device.

53. The use of a compound according to claim 1 in the manufacture of a light emissive device.

54. The use of a compound according to claim 1 in the manufacture of a lithographic device.

55. The use of a compound according to claim 1 in the manufacture of a molecular logic gate.

56. The use of a compound according to claim 1 in the manufacture of a photovoltaic cell.

57. The use of a compound according to claim 1 as a material as a bulk heterojunction compound.

58. A liquid crystal comprising a compound of claim 1.

59. A liquid crystal or a compound substantially as hereinbefore described with reference to the accompanying examples.

P101433 O.2