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1. (WO2004048499) COMBINED ROD-DISC CRYSTALLINE SYSTEMS WITH NEMATIC PROPERTIES
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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, In 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. In the former, the molecules are aligned perpendicularly 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 NDisc and the NCal phase has never been observed experimentally. Minor differences between the NDisc and the NCal phases are that - by definition - the NDisc phase is diamagnetically negative, whereas the NCal phase are positive. The birefringence (Δn≡ ne -n0) of most NDisc phases is negative, and positive 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 NB 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 (NDisc) phase, and more than one rod-shaped groups, promoting the formation of the calamitic nematic (NCal) 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 (NB) phase; thus these mixtures might exhibit NB phase behaviour and could be incorporated in devices making use of the particular properties of the NB 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;


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


wherein D1 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, L1, OL2 and SL3;

E1 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;

Y1 is selected from the group; single bond, O, S, CH2, CO2, OCO, CONH, NHCO, NH and-(C=O)-;

T1 is selected from the group; H, CN, F, CI, CF3, NO2, NCS, SCN, L4, OL5, SL6, CO2L7, OCOL8;

X is represented by 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 E1 or is an aromatic or aliphatic multifunctional moiety, selected from one of the structures of formula V;


[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;

Q1 and Q2, which may be the same or different, are each selected from the group; (CH2)g, (CF2)h, (CH2CH2O)iCH2CH2 and (SiZ12O)-jSiZ22 ,

Z1 and Z2, which may be the same or different, are each selected from CH3, CF3 and

H;

L1, 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 C1-16 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 IV and IVa, 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, OL10 and

SL11;

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, Lu, OL13, SL14, CO2L15 and OCOL16,

L9, L10 and L11, which may be the same or different, are each selected from a C1-5 branched or straight alkyl chain;

L12, L13, L14, L15 and L16, which may be the same or different, are each a C1-16 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.

T1, T2 and/or T3may include one or more non-adjacent CH2 groups that are substituted with CH(CN), CH(CF3), CH(Cl) 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 Q1 and Q2 may be compiled from the fragments described before.

Preferred disc-shaped mesogens are 11-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl alcohol or 11-[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-[1,1';4',1"]terphenyl-4-yloxy)hexyloxy]benzoic acid ethyl ester.

Thus an especially preferred mixed disc-rod mesogen of the invention comprises an ester formed between 11-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl alcohol or 11-[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-[1,1';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 11-[pentakis(4-methoxyphenyletynyl)- phenoxy] undecyl ester; 3,4,5-tris[10-(4'-cyanobiphenyl-4-yloxy)decyloxy]benzoic acid 11-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester; 3,4,5-tris[6-(4'- cyanobiphenyl-4-yloxy)hexyloxy]benzoic acid 11-[pentakis(4-hexyloxy- phenyletynyl)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 11-[pentakis(4- methoxyphenyletynyl)phenoxy] undecyl ester; 3,4,5-tris[6-(4-(4-pentylphenylazo)phenoxy)hexyloxy]benzoic acid 11-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester; and 3,4,5-tris[6-(2,3-difluoro-4"-octyloxy[1,1;4',1"]terphenyl-4-yloxy)hexyloxy]benzoic acid 11-[ρentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester.

A specifically preferred compound which may be mentioned is a compound of formula D1R5, 3,4,5-tris[6-(2,3-difluoro-4"-octyloxy-[1,1';4',1"]terphenyl-4-yloxy)hexyloxy]benzoic acid 11-[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 and/or 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; iii) aq. KOH, EtOH/THF (1:1), reflux 2 hrs; iv) aq. HCl; v) DCC, DMAP,pTSA, 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 "NDisc" and rods "NCal ", the nematic phases are aligned to the director
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 D1 (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 esterification with the discotic mesogen 6 yielded the target material.

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

K2CO3, KI, butanone, reflux 16 hrs; iii) aq. K , EtOH/THF (1:1), reflux 2 hrs; iv)

aq. HCl; v) DCC, DMAP,p TSA, CH2Cl2, room temperature 5 days.

Experimental Section

1. Materials

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 D1 and D2 have been fully described previously. [REF]

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 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


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, H1). 13C NMR (400 MHz, CDCl3): 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/methanol mixtures or CH2Cl2/hexane mixtures) or column chromatography (SiO2, CH2Cl2/hexane mixtures as eluent). 1H NMR (400 MHz, CDCl3): 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, H1). 13C NMR (400 MHz,

CDCl3): 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, CDCl3): δ 7.66, 7.61, 7.51, 6.97 (4xdd, 8H, H1, 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, CDCl3): 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 (k).

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

Synthesis according to the general procedure. Purification by crystallisation from acetone:MeOH and CH2Cl2: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, CDCl3): δ 7.66, 7.61, 7.51, 6.97 (4xdd, 8H, H1, 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, CDCl3): 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 (l); 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, H1). 13C NMR (400 MHz, CDCl3): δ 161.32 (k); 150.98 (g); 146.95 (d); 145.81 (h); 129.02 (e); 124.55 (i); 122.49 (f); 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 (a).

3.6 4-(6-BromohexyIoxy)-2,3-difluoro-4"-octyloxy-[1,1 ';4',1 '']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, CDCl3): 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, H10, H3 and H12, resp.); 1.98-1.25 (m, 20H, H2 and H11); 0.90 (t, 3H, H1). 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); 123.47 (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 (a). 19F NMR (400 MHz, CDCl3): δ -141.51 (d, |3J(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 CH2Cl2/hexane mixtures) or column chromatography (SiO2, CH2Cl2/hexane mixtures as eluent).


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 CH2Cl2). 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, H14); 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, H15). 13C NMR (400 MHz, CDCl3): δ 166.35 0); 159.66 (i); 152.68 (n); 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 (l); 68.92 (l'); 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'-cyanobiphenyl-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, H14); 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, CDCl3): δ 166.44 (y); 159.75 (i); 152.74 (n); 145.22, 145.19 (e); 142.18 (m); 132.53 (c); 131.22 (f); 128.27 (g); 127.02 (d); 125.07 (p); 119.08 (a); 115.03 (h); 110.01 (b); 107.91 (o); 73.40 (l); 69.10 (l'); 68.10 (j); 60.98 (z); 30.28-25.99 (k), 14.39 (aa).

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


Synthesis according to the general procedure. Purification by crystallisation from butanone. Yield: 93 % of a white powder. 1H NMR (400 MHz, CDCl3): δ 7.70-7.59 (m, 9H, H1, H2 and H8); 7.55-7.48 (m, 5H, H3 and H9); 6.98 (dd, 4Η, H4); 6.86 (dd, 1H, H10); 4.33 (q, 2H, H14); 4.04, 4.03 and 3.99 (3xt, 12H, H7 and H5); 1.90-1.75 and 1.53-1.28 (2xm, 32H, H6); 1.35 (t, 3H, H1S). 13C NMR (400 MHz, CDCl3)

δ 166.53 (y); 159.77 (i); 153.03 (n); 148.43 (m); 145.25 (e); 132.55 (c); 131.25 (f); 128.30 (g); 127.04 (d); 123.43 (o); 122.78 (q); 119.09 (a); 115.05 (h); 114.23 (p); 111.87 (r); 110.25 (b); 69.22, 68.95 (l); 68.12 (j); 60.70 (z); 29.48-29.95 and 26.02- 25.93 (k, k'), 14.39 (aa).

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


Synthesis according to the general procedure. Purification by multiple crystallisations from acetone and CH2Cl2 :hexane mixtures. Yield: 62 % of a yellow-orange powder. 1H NMR (400 MHz, CDCl3): δ 7.88-7.72 (m, 12H, HS and H6); 7.29-7.21 (m, 8H, H4 and H11); 6.98-6.89 (m, 6H, H7); 4.33 (t, 2H, H12); 4.05-3.92 (m, 12H, H8 and H14); 2.64 (t, 6H, H3); 1.91-1.25 (m, 42H, H2 and H9); 1.37 (t, 3Η, H15); 0.88 (t, 3H, H1). 13C NMR (400 MHz, CDCl3): δ 166.45 (y); 161.42, 161.40 (k); 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 (i); 122.54 (f); 114.68 (j); 108.01 (r); 73.70 (n); 68.99 (n'); 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 (aa); 14.08 (a).

4.6 3,4,5-tris[6-(2,3-difluoro-4"-octyIoxy-[1,1';4',1'']terphenyl-4- yIoxy)hexyloxy]benzoic acid ethyl ester


Synthesis according to the general procedure. Purification by column chromatography (SiO2, 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, CDCl3): δ 7.64, 7.45 (m, 18H, H7, H5 and H6); 7.24 (s, 2H, H13); 7.22-7.07 (m, 3H, H8); 6.98-6.92 (m, 6H, H4) 6.68-6.80 (m, 3H, H9); 4.36 (q, 2Η, H14); 4.10-3.95 (2xm, 18H, H10, H3 and H12); 1.98-1.25 (m, 60H, H2 and H11); 1.35 (t, 3H, H15); 0.89 (t, 9H, H1). 13C NMR (400 MHz, CDCl3): 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 (aa); 14.10 (a). 19F NMR (400 MHz, CDCl3): 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 para--oluene sulphonic acid (pTSA, 0.5 eq.) in CH2Cl2 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 CH2Cl2hexane or CH2Cl2aceton). 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-yloxy)hexyloxy]benzoic acid 11- [pentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester

Synthesis according to the general procedure. Purification using column chromatography (SiO2, eluent CH2Cl2: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, H1-3 and H17); 7.25 (s, 2H, H8); 6.90-6.74 (m, 16H, H4 and H18); 4.33 (t, 2H, H14); 4.27 (t, 2H, H16); 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 H15). 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 (af); 119.85 (ad); 119.11, 119.08 (a); 115.69, 115.56, 115.46 (ai); 115.02 (h); 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 (l'); 68.11, 68.07 (j,j'); 65.20 (z); 55.34, 55.32 (am); 30.60-25.04 (k and aa).

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 CH2Cl2:hexane (2:1) to CH2CI2) and crystallisation from MeOH:CH2Cl2. Yield: 36 % of a pale sticky yellow solid. 1H NMR (400 MHz,

CDCl3): δ 7.67-7.45 (m, 28H, H1-3 and H17); 7.25 (s, 2H, H8); 6.90-6.74 (m, 16Η, H4 and H18); 4.33 (t, 2H, H14); 4.27 (t, 2H, H16); 4.03, 4.01, 3.98 (4xt, 12H, H7 and H5); 3.83, 3.82, 3.81 (3xs, 15H, H19); 1.92-1.25 (m, 66H, H6 and H15). 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 (aj); 132.54, 132.52 (c); 131.21, 131.17 (j); 128.40 (ac); 128.28 (g); 127.01 (d); 125.12 (p); 123.87 (af); 119.85 H; 119.11, 119.08 (a); 115.69, 115.56, 115.46 (ai); 115.02 (h); 114.12, 114.09, 114.08 (ak); 110.02, 109.96 (b); 107.95 (o); 99.20, 98.99, 96.9 (ag); 86.63, 86.08, 83.58 (ah); 74.61 (v); 73.42 (I); 69.12 (I'); 68.11, 68.07 (j, j ''; 65.20 (z); 55.34, 55.32 (am); 30.60-25.04 (k and a aa.

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 (SiO2, eluent EtOAc:hexane (3:2)) and crystallisation from MeOH:CH2Cl2. Yield: 41 % of a pale yellow powder. 1H NMR (400 MHz, CDCl3): δ 7.65-7.39 (m, 28H, H1-3 and H17); 7.25 (s, 2H, H8); 6.88-6.75 (m, 16Η, H4 and H18); 4.30 (t, 2H, H14); 4.27 (t, 2H, H16); 4.01 (t, 12H, H7) 3.98-3.91 (m, 16H, H5 and H19); 1.92-1.25 (m, 82H, H6, H15 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 (i); 152.69 (n); 145.14, 145.09 (e); 142.06 (m); 133.24, 133.10, 133.06 (aj); 132.51 (c); 131.19 (f); 128.37 (ac); 128.26 (g); 126.98 (d); 125.25 (p); 123.87 (af); 119.80 (ad); 119.06, 119.02 (α); 115.21, 115.14, 115.10 (af); 114.98 (h); 114.61, 114.59, 114.58 (a k); 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 (l'); 68.09 (am); 67.99, 67.90 (j); 65.23 (z); 31.58-22.58 (k, aa and an); 14.02 (ao).

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 (SiO2, 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, CDCl3): δ 7.68-7.59 (m, 9H, H1, H2 and H8); 7.57-7.44 (m, 15H, H3, H9 and H17); 6.94 (dd, 4H, H4); 6.86-6.73 (m, 11H, H10 and H18); 4.35 (t, 2H, H16); 4.27 (t, 2H, H14); 4.04, 4.03, 3.99 and 3.97 (4xt, 12H, H7 and H5); 3.85-3.84 (3xs, 15H, H19); 1.92-1.25 (m, 50Η, H6 and H15). 13C NMR (400 MHz, CDCl3): δ 166.56 (z); 159.99, 159.89, 159.80 (al); 159.85 (ac); 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 (af); 123.38 (p); 122.77 (q); 119.83 (ad); 119.07 (a); 115.69, 115.53, 115.45 (ai); 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 (j); 67.90 (z); 55.30, 55.28 (am); 30.56-25.90 (k 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 (SiO2, 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, CDCl3): δ 7.68-7.59 (m, 9H, H1, H2 and H8); 7.57-7 '.44 (m, 15H, H3, H9 and H17); 6.94 (dd, 4H, H4); 6.86-6.73 (m, 11H, H10 and H18); 4.35 (t, 2H, H16); 4.27 (t, 2H, H14); 4.04, 4.03, 3.99 and .3.97 (4xt, 12H, H7 and H5); 3.85-3.84 (3xs, 15H, H19); 1.92-1.25 (m, 50H, H6 and H15). 13C NMR (400 MHz, CDCl3): δ 166.56 (z); 159.99, 159.89, 159.80 (al); 159.85 (ac); 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 (αc); 128.25 (g); 126.99 (d); 123.82 (αf); 123.38 (p); 122.77 (q); 119.83 (ad); 119.07 (a); 115.69, 115.53, 115.45 (ai); 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 (0; 68.08 (j); 67.90 (z); 55.30, 55.28 (am); 30.56-25.90 (k and 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 CH2Cl2: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, H5 and H6); 7.56-7.48 (m, 10H, H17); 7.29-7.22 (m, 8H, H4 and H11); 6.95-6.89 (m, 6H, H7); 6.88-6.81 (m, 10H, H18); 4.31 (t, 2H, H14); 4.25

(t, 2H, H16); 4.03, 4.00 (2xt, 12H, H8 and H10); 3.81, 3.80 (2xs, 15H, H19); 2.63 (t, 2H, H3); 1.91-1.21 (m, 60H, H2, H9 and H15); 0.87 (t, 3H, H1). 13C NMR (400 MHz, CDCl3): δ 166.32 (y); 161.22 (k); 159.89, 159.79, 159.70 (al); 159.77 (ac); 152.60 (p); 150.87 (g); 146.79, 146.76 (d); 145.62, 145.60 (h); 142.00 (o); 133.15, 133.02, 132.99 (aj); 128.88 (e); 128.28 (αc); 125.11 (q); 124.42 (i); 123.73 (af); 122.38 (f); 119.74 (αd); 115.61, 115.44, 115.37 (ai); 114.48 (j); 114.00, 113.96 (ai); 107.84 (r); 99.05, 98.88, 96.82 (ae); 86.51, 85.98, 83.45 (aj); 74.50 (ab); 73.15 (n); 68.83 (n'); 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-[1,1':4',1"]terphenyl-4-yloxy)hexyloxy] benzoic acid 11-[pentakis(4-methoxyphenyletynyl)phenoxy] undecyl ester

6.1 4-(6-Bromohexyloxy)-2,3-difluoro-4 -octyloxy-[1,1';4',1"]terphenyl (3).

A mixture of the aromatic alcohol 4-hydroxy)-2,3-difluoro-4"-octyloxy-[1,1';4',1"]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, CDCl3): δ 7.62, 7.58, 56, 6.99 (4xdd, 8H, H7, H5, H6 and H4, resp.); 7.14, 6.82 (2xtd, 2H, H8 and H9); 4.10, 4.01, 3.45 (3x×, 6Η, H10, H3 and H12, resp.); 1.98-1.25 (m, 20H, H2 and H11); 0.90 (t, 3H, H1). 13C NMR (400 MHz,

CDCl3): 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); 123.47 (m); 122.78 (l); 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). 19F NMR (400 MHz, CDCl3): 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-[1,1';4',1'']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 CH2Cl2 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.


1H NMR (400 MHz, CDCl3): δ 7.64, 7.45 (m, 18H, H7, H5 and H6); 7.24 (s, 2H, H13); 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 H11); 1.35 (t, 3H, H15); 0.89 (t, 9H, H1). 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 (αα); 14.10 (α). 19F NMR (400 MHz, CDCl3): 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''-octyloxy-[1,1';4',1"]terphenyl-4-yloxy)hexyloxy]benzoic acid 11-[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 CH2Cl2) 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, H7 and H17); 7.25 (s, 2H, H13) 7.10-7.01 (m, 3H, H8); 6.97-6.92 (m, 6Η, H4); 6.90-6.85 (m, 10H, H18);

6.11-6.69 (m, 3H, H9); 4.33 (t, 2Η, H14); 4.29 (t, 2H, H16); 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, H11 and H15); 0.89 (t, 3H, H1). 13C NMR (400 MHz, CDCl3): δ 166.45 (y); 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 (i); 128.41 (ae); 126.68, 126.66 (f);

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

115.47 (ai); 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, CDCl3): 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 (D1 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.


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 TNI 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 TNI. 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, 123,, 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, W.F.; Mijs, W.J.; Picken, S.J. J. Mater. Chem., submitted for publication.