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Title:
LATERALLY CYANO- AND FLUORO-SUBSTITUTED TERPHENYLS
Document Type and Number:
WIPO Patent Application WO/1989/003821
Kind Code:
A1
Abstract:
Laterally cyano-substituted terphenyls of formula (I), wherein R1 and R2 are independently selected from hydrogen or C1-15 alkyl, alkoxy, or alkyl or alkoxy in which one or more CH2 groups are replaced by O, COO, OOC, CHX, CX2, CH=CX, CX=CH, CX=CX, where X is fluorine or chlorine, CRCN where R is alkyl, or C=C, or in which a terminal CH3 of the said alkyl or alkoxy chain is replaced by CF3, n is 0 or 1, and the CN and F (if present) substituent are independently located in any of the available substitution positions. Liquid crystal materials containing these terphenyls are also described.

Inventors:
Gray
George
William, Lacey
David, Hird
Michael, Toyne
Kenneth
Johnson
Application Number:
PCT/GB1988/000880
Publication Date:
May 05, 1989
Filing Date:
October 19, 1988
Export Citation:
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Assignee:
THE SECRETARY OF STATE FOR DEFENCE IN HER BRITANNIC MAJESTY'S GOVERNMENT OF THE UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND GRAY
George
William, Lacey
David, Hird
Michael, Toyne
Kenneth
Johnson
International Classes:
C07C255/50; C07C255/54; C07C255/55; C07C255/57; C09K19/12; C09K19/42; (IPC1-7): C07C121/64; C07C121/75; C09K19/12; C09K19/42; C09K19/44; C09K19/46; G02F1/13
Foreign References:
DE3216281C21984-07-12
EP0132377A21985-01-30
US4632515A1986-12-30
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Claims:
1. Cl im A la terally cyano^ubs ituted terphenyl characterised bv a general ^ormul : wherein R.
2. and B.
3. re independently selected from hydrogen or C alkyl, alkoxy, or alkyl or alkoxy in which one or more CH„ groups are replaced by 0, COO, 00G, CHX, CX2, CH=CX, CX=GH, GX=CX, where X is fluorine or chlorine, CRCN where R is alkyl, or C≡C, or in which a terminal CH, of the said alkyl or alkoxy chain is replaced by CF~, n is 0 or 1, and the CN and F (if present) substituent are independ¬ ently located in any of the available substitution positions.
4. 2 A terphenyl according to claim 1 characterised by a general '"or ula: A B C D E G wherein R and R are independently alkyl, alkoxy or alkynyl, and the terphenyl has a substitution pattern selected from any one of the following substitution patterns: (D = CN), (A = CN), (B = F, G = CN), (A = CN, B = F), (B = CN), (C = CN, D = F), (A = F, G = CN), (A = F, E = CN), (B = F, E = CN), (B = F, D = CN), (A = F, D = CN), (A = F, c.= CN), ( B = F, c = CN), ( A = F, B = CN ) the remaining lateral substitution positions being occupied by hydrogen. i J . A terphenyl according to claim 2 characterisei in that R~ and '2 R are independently selected ^rom nalkyl or nalkoxy containin ^ 12 carbon atoms.
5. A tsrphenyl according to claim 3 characterised by a formula selected from the two below: CN F F CH κ ©U© B1^®®*2 .
6. A e hen l according to claim ° characterised by a formula: GN ,2 ~ &<3>&> •R 3 A terphenyl according to claim 3 characterised by a formula; A liquid crystal material, being a mixture of compounds, characterised in that at least one of said compounds is a terphenyl as claimed in claim 1.
7. 10 A liquid crystal material being a mixture of compounds. characterised in that at least one of said compounds is a terphenyl as claiπe""' in claim 2.
8. 11 A liquid crystal material according tc claim 10, characterise" in that at least one of saiI compounds is a terphenyl o"~ formula: wherein R 1 and ?.~ r~~ are independently C^ C1 . nalkyl or nalkoxy.
9. 12 A liquid crystal material according to claim 10, 12 (contd.) characterised in that at least one of sail compounds is •:.. terphenyl of ormula: whe eein ~ and are independently C,, Q nalkyl cr nalkoxy.
10. 13 A liquid crystal material according to claim 10, characterised in that at least one of said compounds is a terphenyl having a formula selected from the two below: where:n R" an." R are independently ~~ G,2 nalkyl or nalkoxy V1 ■ A liqui' crystal material according to any one of claims 9 to 1/ characterised in that the material additionally contains one or "lore fluorin ted terphenyls of general formula: 3 4 ___ _. where R and R are independently selectedfrom hydrogen, alkyl and alkoxy each containing 112 carbon atoms, p may be 1 or 2 and the fluorosubstituents(s) may occupy any of the available lateral substi¬ tution positions. 15 A liquid crystal material according to claim 14 characterised in thε.t the fluorinated terphenyl has a formula selected from one or more ox' the following: ®*1 16 A liquid crystal material according to a,ny one of claims 9 to 1" characterised in that the mixture additionally contains one A wherein R" and y independently contain 1 12 carbon atoms. ? is nalkyl or nalkoxy. R is nalkyl.
11. 17 A liquid crystal material according to claim 9 or claim 10 characterised in that the mixture additionally contains one or more optically active compounds of formula: wherein RΛ is 0 C nalkyl or nalkoxy, (F) indicates that the * "B phenyl ring may carry one or more fluoro substituents, E is C ( nalkyl, cycloalkyl, o a branche" alkyl group of formula: where a is 0 or an integer 1 6 and each of b an", c is an integer 1 6.
12. 13 Use in a liquid crystal electro optical display device in the form of two substantially parallel substrates at least one of which is optically transparent and having electrodes on their facing surfaces o^ a liquid crystal material as claimed in claim Q or 10.
Description:
LATERALLY CYANO- AND FLUORO- SUBSTITUTED TERPHENYLS This invention relates to laterally cyano- and fluoro- substi¬ tuted terphenyls, in particular to those which may be used as con¬ stituents of liquid crystal mixtures. The invention also relates to such mixtures containing these terphenyls and to electro-optic devices which use them.

Liquid crystal materials are well known, and are commonly used in electro-optical devices such as watches, calculators, displays etc. Such materials are of two general types. There are those which use the electro-optical properties of the nematic (N) phase, such as the electrically controlled birefringence (ECB) effect, as described in M.F. Schiec el and K.Fahrenshon, "Defomation of nematic liquid crystals with vertical orientation in electrical fields". Appl Phys Lett (1971), 19, 3912. There are also those which use the electro- optical properties manifested by smectic phases. Examples of the latter include the ferroelectric effect manifested by certain chiral tilted smectic phases, see for example N A Clark and S T Lagerwall .

Appl-Phys Lett (1980) 36, 899 which offers the advantages of high speed and bistable properties. The chiral smectic C, F and I phases

* * * (Sc Sp and Si) i ^ the asterisk denoting chirality) are generally most

* favoured for such use, the S c being preferred because of its lower viscosity. Another electro-optical effect in smectic phases is the fast-switching electroclinic effect manifested by smectic A phases

(S A ).

Nematic and ferroelectric smectic liquid crystal materials have a number of desirable requirements in common, which for example include ease of preparation, chemical and photochemical stability, low vis- t cosity and a broad temeprature range over which the useful phases

(eg N, S„ _, S_ ε or S x 1) persist. Such materials are generally mixtures of compounds and these requirements are sought in compounds or mix- tures thereof intended for use in the materials.

Materials and compounds for use in ECB devices and S* devices have a number of specific desirable requirements. For example for use in ECB devices, compounds and materials should preferably show a high value for the ratio of elastic constants K K , high values for the optical ε-nir.otrσpy in and a negative dielectric aniεotropy ΔE. Indevices which use the ferroelectric effect in S* materials it

is desirable that compounds and mixtures show an S phase at a tem¬ perature above the range over which the S* phase persists, and that undesirable phases such as S do not appear.

A number of compounds are known which show broad S phases, among which are the alkyl- or alkoxy- terminated fluoroterphenyls ("FTP's") described in EP-A-0132377, of general formula:

F

where R and R are alkyl or alkoxy. Some FTPs and mixtures thereof are known to show broad temperature range S-- phases. This has made them excellent candidates for constituents of. ferroelectric smectic mixtures.

See for example their use in the mixtures disclosed in PCT/GB 87/0441 and GB 8627107.

It is an object of the present invention to provide novel compounds which may be used as constituents of liquid crystal mixtures, and novel liquid crystal mixtures which incorporate them.

According to this invention novel laterally cyano-substituted terphenyls general formula I below are provided:

*: 7:""."~T ' —1 " ~ "* -t_

The structural preferences discussed below are based on inter alia on ease of preparation and suitability for use as constituents of liquid crystal mixtures and electro-optical devices which use them-

Preferred structures for terphenyls of formula I are those having a general formula IA below:

wherein R and and the terphenyl has a substitution pattern selected "rom any one of the following substitution patterns: (D = CN), (A = CN), (B = F, G = CN), (A = CN, B = F), (B = CN), (C = CN, D = F), (A = F, G = CN), (A = F, Ξ = CN), (B = F, E = CN), (B = F, D = C ) , (A = F, D = CN), (A = F, C = CN), ( B = F, C = CN), ( A = F, B = CN ) the remaining lateral - boti tion positions " bein? occu-ie 5 by hy ; ro≤ren-

The structures included in formula IA are listed below in Table 1.

Table 1

S OXOKO F'

<2) --@fe oV-

Table 1 ζ contd. N

' - " , F " = s .I "l , a c y or al'-c nyl

30

35

of the structures listed in Table 1, structures 1.1, 1.3, 1.4, 1.5- . ~ __Α 1.1'. are particularly -y-eferred. esOecialϋy 1.1, 1.3, lΛ, 1 10.

1 2 In compounds of formula I, IA or as listed in Table 1, R and R are preferably independently n-alkyl, n-alkoxy or n-alkvnyl containing 3-12 especially 3-10 carbon atoms, or branched or asym¬ metrically substituted alkyl, alkoxy or alkynyl, which may be in an optically active or racemic form, but especially n-alkyl or n-alkoxy.

?, an ?_ may be the same or di f ferent .

1 2 In a compound of formula 1, R and R may therefore be indepen- dently selected from the following preferred groups listed in Table 2 below:-

Table 2 n-alkyl n-alkynyl

C 3 H 7 C 2 H 5 C,C

C 3 H 7 C C

C 4 H 9

C 5 H 11 C 4 H 9 C≡C

C H C ,JB, _, C=C __-> -~~ c - 7_ H 1-, 5_-

C 8 H 17 C 7 H 15 C≡C C 9 H 19 C 8 H 17 C≡C

C- Λ H Λ _ C_H_ _C~C

10 21 9 19 C 11 H 23 ' C 10 H 21 C - C C 12 H 25

Preferred asymmetrically substituted alkyl and alkoxy groups are 2-methylbutyl, 2-methylbutyloxy, 3-methylpentyl, 3-methylpentyloxy, 4-methylhexyl, 4-methylpentyl, 1-methylheptyl and 1-methylheptyloxy.

Preferred asymmetrically substitutedalkynyl groups are:-

CH CH PCHCH QΞC- 3 2 2

Compounds of formula I may be prepared via a number of synthetic routes, for example routes A - F shown in the accompanying figures 1-11, route B providing some useful intermediates. The respective structural types which, may be prepared using these routes are as follows, referring to Table 1 above:-

Structure Route

Modifications to routes A-F to prepare compounds in which the substituents R and R of Table 1 are different to those illustrated in figures 1 to ll will be apparent to those skilled in the art of organic synthesis, for example the replacement of the alkyl or alkoxy

1 2 groups R, R , R R" by their perfluorinated analogues or by alkynyl or alkynyloxy groups. -

Althoug the overall routes A-F and their end products are novel the individual steps use known reactions.

For example the following steps use the known coupling reaction between the halo-phenyl ring and the phenylboronic acid in the presence of tetra-(triphenylphosphine)-palladium (0): All, A23, A24, C14, C23, C25, D13, D22, D42, D44, E12, E22, E23, Fll, F21, F31, F32, F43, F44.

The phenylboronic acids used in these steps may in turn be produced from the halophenyl precursor by the known method which first prepares a Grignard Reagent using Magnesium in tetrahydrofuron (THF) followed by a reaction with tri-isopropylborate then hydrolysis with hydrochloric

acid. This procedure is used in steps B13, B22, C13, D41, D43, Ell,

F42.

In routes Dl, D2, D3 and D4 the lateral CO H group is introduced into the fluorinated ring using n-Butyl-lithium in hexane followed by reaction with carbon dioxide then hydrolysis. The CO H group is then converted into the corresponding amide using oxalyl chloride and ammonia, followed by dehydration using thionyl chloride.

Other known reactions used in these routes are as follows:-

A21, 5^5 - N-bromoεuccinimide/dichloromethane 0°C A22. P^6 - (i) NaN0 2 /HCl (ii) KI

Bll - Friedel Crafts reaction, RCOC1/A1C1

B12- ~ ^S - via nydrazine hydrate ( ^Sa = iirect uπe)

B21, Cll, D21, F41 - RBr/acetone/K CO

C12 - Br„ 2 C21, ≠-γ - F.-CSCH, ZnCl ? : P^H-h,^

C22 - H , Pd/C

Apart from standard reagents the starting materials for routes

A-F are known or commercially available, eg from BDH Ltd or Fluorochem.

A method for the preparation of the terphenyl starting point of route D3 is found in EP-A-0132377. In routes A-F when the starting compound may be made by one or more of the other routes this is indicated, eg

(C13) in route C2 shows that this starting compound may be made via step C13.

It should also be noted that the products of steps D13, D22 and D43, and the starting compound for step D3.1 are protected by the claims of the Applicant's EP-0132377-B and US Patent 4,594,465.

To prere.re compound? in which F.~ and/or H contain fluorine, the appropriate per luorcalkyl compound? may be use J as starting points, eg: in steps Ell or B22 etc.

-ι , p Compounds in which r an ' /or R ~ contain a COG or OOC group, eg

RCGG- where ? is alkyl ray ""or example be prepared by removing a terminal

R or y group which is alkoxy from a terphenyl product of formula I or

IA using the known method of reaction with E3r„ followed by hy d rolysis to leave a terminal -OH group, f ollowed by esterification of this phenol with a carboxylic acid ICCOH or an acyl chloride RC0C1.

The C=C group in compounds in which R ~ anI /or R is alkynyl is a reactive functional group and may for example be hydrateά, eg using H SO^ / H^SO, or BH to yield terminally ketone substituted terphenyls, eg having terminal -C0.CH„-R or -CH_C0.-R groups. Such ketones may be reduced to form the corresponding alcohols, ie

-CH(OH)GH 9 -R or -CH_GH(0H)-R, which may themselves be esterified with a carboxylic acid to form the corresponding esters.

Alternately the ketones may be converted into cyanohydrins by reaction with HCN, leaving terminal groups of structure -G.CIT.OH-GH -R and -CH^-C.CN.OH-R . Such cyanohydrins may then be esterified eg with a carboxylic acid R"-C00H where I-" is alkyl to yield terphenyls with one or more terminal substituent groups of structure: CN CN

I I

R"C00-C- or R"G00-G-GH - CH 2 R R

Also reaction of the C= G group with halogens or hydrogen halides can lead to terphenyls of formula I with halogenated terminal substituents P. and / or R . For example well known reactions o an alkyne subs-it ent R-CΞG such as in the product of step C25 can lead in this way to R-CXgC ^, E-CHX=CHX-, R-CH 2 CX 2 - and B-CXgCE,- where X is a halogen eg chlorine.

føiny terphenyls of formula I show liquid crystal phases, and also a high negative dielectric anisotropy , E. These are therefore useful components of liquid crystal materials, and therefore accord¬ ing to a further aspect of this invention there is provided a liquid c crystal material, being a mixture of compounds, at least one being a terphenyl of formula I , preferably formula IA.

Such a liquid crystal material may be a nematic or smectic liquid crystal material.

20 A nematic liquid crystal material may therefore be a mixture of compounds at least one of which is a terphenyl of formula I, prefer¬ ably one which exhibits a nematic liquid crystal phase. As terphenyls of formula I have a high negative l_.∑ they may usefully be mixed with other compounds which show nematic liquid crystal phases and which for

y z. example have a low »E,or a positive&E to provide a mixture of inter¬ mediate £»E.As is well known in the liquid crystal art, the sign o £kE (ie +ve or -ve) of a nematic liquid crystal material is chosen according to the kind of electro-optical device in which the material is to be used. Hence the availability of the high negative _E

20 compounds of the invention is very advantageous. In particular the terphenyls of the invention are likely to be useful in liquid crystal mixtures which use the ECB effect.

The general classes of other compounds which may be included in 2 ~ a nematic liquid crystal material according to this aspect of the invention will be well known to those skilled in the liquid crystal art. Some examples of compounds having a lowΔE are listed below:

■> _ H -0- C V H 2^-(0>- H'

Some examples of compounds having a positiveAE are listed below:

*-g>-<§)-CN R -Q-CK 2 CH 2 -g>-CN

2?

Where R and R' independently represent C. - Co alkyl or alkoxy, and X represents P or H.

The nematic liquid crystal mixture of this aspect of the inv¬ ention may also contain pleochroic dyes, such as those described in 2 ~ EP-A-S2300 c i91, and/or one or more optically active compounds to in¬ duce the appeamnce of a cholesteric phase.

Typically but not exclusively a nematic liquid crystal mixtur of this aspect of the invention contains:

Compounds of formula I: - 95 w % 0 Low b_ E compounds: 0 - 95 wt %

High +ve E compounds: 0 - 95 wt %

Optically active compounds: 0 - 5 wt

Pleochroic dyes: 0 - 5 wt

The overall sum of weight percentages being 100 wt %.

° < 5

The invention also provides a smectic liquid crystal material which is a mixture of two or more compounds, at least one of which is a terphenyl of formula I, preferably of formula IA, and especially of formula 1.1 or 1.4 of Table 1. This mixture preferably also contains in addition one or more other compounds which together or separately show a smectic phase. The smectic phase is preferably S , S or S / Preferably the mixture of this aspect of the invention contains one or more terphenyls of formula I and one or more FTP'S of formula

Formula II

3 where R and R are independently selectedfrom hydrogen, alkyl and alkoxy each containing 1-12 carbon atoms, p may be 1 or 2 and the 15 fluorosubstituents(s) may occupy any of the available lateral substi¬ tution positions. Preferred FTP's for this aspect of the invention have a formula IIA, IIB or IIC.

X Y Formula IIA

Formula IIB

25

E Formula TIC

3 4 where R and R are as defined above, and where X and Y are mdepen-

30 dently selected from hydrogen and fluorine, at least one of X and Y

3 4 being fluorine. Preferably R and R are n-alkyl or n-alkoxy con¬ taining 3-12 carbon atoms, especially 3-10.

3 4 R and R may be the same or different. Preferred n-alkyl and n-alkoxy groups from which R and R may be selected are those from

_ -_ 1 2 which R and R are selected, as listed above, although the combinations

1 2 3 4 . of R and R need not be the same as R and R in the mixture.

Preferably X in formula IIA is hydrogen and Y is fluorine. The preparation of such FTPs is described for example in EP-A-0132377. The preparation of FTPs in which p is 2, eg of formula IIB and IIC is described in GB-A-8806220 filed 16-03-88, the contents of which are incorporated herein by reference.

The smectic liquid crystal material of this aspect of the invention may for example show an Sc phase at room temperature, and may be a mixture of one or more FTPs of formula IIA plus one or more terphenyls of the invention, or may be a mixture of one or more FTP'S of formula II B and or one or more FTP's of formula IIC plus one or more ter¬ phenyls of the invention.

The addition of one or more compounds of formula I to one or more FTPs of foru ula II often results in suppression of undesirable S

B phases shown by the FTP, and may also result in a mixture showing an S phase over a broader temeprature range than the FTP. This is particularly so with FTP's of formula IIA. These effects may be mani¬ fested at quite low ratios of formula I compound(s) to FTP's, for example typically in the range 1:20 to 1:5 by weight % of formula I compound(s) to FTP(s). Other compounds which show an S phase and which may be used in mixtures of this aspect of the invention are the known compounds:

where R , R and R" independently contain 1 - 12 carbon atoms, R and are independently n-alkyl or n-alkoxy, and R is in d ependently n-alkyl

With the smectic mixtures of this aspect of the invention may be mixed one or more optically active compounds which induce the mixture

to show an S* phase and/or increase the P of the mixture. The mixtures produced in this way are ferroelectric mistures showing a P value and o are a further aspect of this invention. The use of terphenyls of the invention in such mixtures may result in advantageous P values and switching times.

Many optically active compounds are known which may be used in this way. Preferred optically active compounds are those described in PCT GB 85/0512, eg

the compounds described in EP-A-0110299, eg

the compounds described in PCT/GB 87/00280, eg

and in particular the compounds described in PCT/GB87/00441 which contain a C00CH(CN)R group where R is alkyl, for example:

where ^ is n-alkyl or n-alkoxy containing 5-12 carbon atoms, (F) indicates that the phenyl ring may carry a fluoro substituent, an d R B is C]_-4 n-alkyl, cycloalkyl or a branched alkyl of formula:

where a may be 0 or an integer 1-6, and each of b and c is an integer

1-6, preferably a being 0 and at least one of b or c being 1.

Pre erred groups R " In coπrpounis VII are methyl, -CHfCH-)-, -CH.GH^.^CH^ and cyclohsxyl.

Additives if used in such mixtures may fulfill a number of functions. For example additional optically active compounds may be included to control the pitch of the S Q phase such as the optically active amide compounds described in PCT GB 87/00223, eg

GEL, H i J i A - -@ 00CJlC0N- -R B VIII 0 or the optically active terphenylsdescribed in GB 8703103 eg

where R A , RB a ntai•ni•ng 5 1-12 carbon atoms, D is F or Cl, X is 00CCH(CH 3 )0R", OGH(GH 3 )COOR" or G00CH(CH„)R" where R" is n-alkyl containing from 1 to 12 carbon atoms.

Additives may also serve the function of encouraging the formation of an S phase at a temperature above that of the S* , to assist in

A C 0 alignment of the mixture with the electrodes of an electro-optic device. Additives may also suppress undesirable phases such as S or S so that these occur at temperatures far away from the working temperature range, eg p

R ^-^-COO-^-R 1

A B where R and R are independently n-alkyl or n-alkoxy containing 1-12 carbon atoms.

~ \f ~

Typically but not exclusively a smectic C liquii crystal terial of this aspect of the invention is a mixture having a composition as follows:

The nematic and ferroelectric smectic liquid crystal mixtures of the invention may be used in any of the known types of liquid crystal electro-optical display device which use such materials, for example as described in the two Appl. Phys. Lett, references mentioned above.

The construction and method of operation of such liquid crys¬ tal electro-optical devices is well known. Generally such a device comprises two substantially parallel substrates, at least one of which is optically transparent, and having electrodes on their facing surfaces, and sandwiched between them a liquid crystal mat¬ erial. The application of a voltage across the liquid crystal mat¬ erial via the electrodes causes a change in the optical properties of the liquid crystal material to produce a visible effect. Suitable dimensions, voltages and other parameters for such a device will be apparent to those skilled in the art.

The invention will now be described by way of example only with reference to the accompanying figures 1 - 11 which show prep¬ arative routes for terphenyls of the invention and figure 12 which shows a cross section through a liquid crystal device.

In the following examples all temperatures are in [ he abbreviations N = nematic, S. = smectic A, S_ = smectic C, 3, and S„ unidentifi d smectic pha.se, I = isotropic liquid, K = soli": crystal. I . icuid crystal transitions shown ( ) are virtual transitions seen on supercoolin g .

Preparative Examples.

Example 1

Using routes Al, A2, Bl and B2 the following compounds oi structure 1.1 were made:

Route Bl

s the presence of aluminium chloride. Step B 12 n - c K i l "®- Er

A mixture of the product of step Bll (77.1g, 0.32 mol), hydrazine hydrate (46.4g, 0.93 mol) and potassium hydroxide (59.0g, 1.05 mol ) in diethylene glycol (250 ml) was heated at 130°C for 2h. The excess of hydrazine hydrate was distilled off and the temperature was raised to 200°C for 2h. The cooled mixture was poured into 18% hydrochloric acid, the product was extracted into ether (twice), and the combined ethereal extracts were washed with water and dried (MgS04). The solvent was removed in vacuo and the residue was distilled to yield a colourless liquid. The identity of the product was confirmed by nmr, ir and MS. Yield 58 * lg (80%), bp 145-148°C at 20mm Hg.

A solution of the Grignard reagent prepared from the product of step B 12 (24.Og, 0.11 mol) and magnesium (2.95g, 0.12 mol) in dry THF (85 ml) was added dropwise to a stirred, cooled (-78°C) solution of tri-isopropyl borate(39.8g, 0.21 mol) in dry THF (25 ml) under dry nitrogen. The stirred mixture was allowed to warm to room temperature overnight and stirred for lh with 10% hydrochloric acid (120 ml) at room temperature. The product was extracted into ether (twice), and 0 the combined εtheral extracts were washed with water and dried (MgSO ). The solvent was removed in vacuo to afford a soft off-white solid. Yield 19.3g (95%). The identity of the product was confirmed as above.

Route B2

A solution of 1-bromohexane (60.Og, 0.36 mol) in acetone (150ml) was added dropwise to a stirred mixture of 4-bromophenol (71.0g,

0.41 mol) and potassium carbonate (120.Og, 0.87 mol) in acetone (600ml) 0 a room temperature. The stirred mixture was heated under reflux (90-95°C) for 43 h (ie until glc analysis revealed an absence of 1-bromohexane) . The product was extracted into ether (twice), and the combined ethereal extracts were washed with water, 5% sodium hydroxide, water and dried (MgSO ) i The solvent was removed in vacuo 5 and the residue was distilled to yield a colourless liquid. Yield

79.4g (86%), bp 100-110°C at 0.1mm Hg. The identity of the product was confirmed as above.

Step B22 / - 0H

? A solution of the Grignard reagent, prepared from the product of step 321 (72.Og, 0.28 mol) and magnesium (7.75g, 0.32 mol) in dry THF (220 ml) was added dropwise to a stirred, cooled (-78°C) solution of tri-isopropyl borate(109.1g, 0.58 mol) in dry THF (40 ml) under dry nitrogen. The stirred mixture was allowed to warm to room temperature 5 overnight and stirred for lh with 10% hydrocholoric acid (320 ml) at room temperature. The product was extracted into ether (twice), and the combined ethereal extracts were washed with water and dried (MgSO ) . The solvent was removed in vacuo to afford a colourless solid. Yield 61.2g (99%) mp 80-85°C. The identity of the product was confirmed as above.

Route Al

Step Ail CN,

Br -^-fOVH-Br

Bromine (44.Og, 0.275 mol) was added dropwise to a mixture of benzonitrile (10.Og, 0.097 mol) and aluminium chloride (42.Og, 0.31 mol) at room temperature. The mixture was heated at 70°C for 3.5h and poured into ice/water. The product was extracted into ether (twice) and the combined ethereal extracts were washed with sodium thiosulphate i _.n_ and dried (MgSO4). The solvent was removedin vacuo to afford an off- white solid (23.4g) (glc analysis revealed presence of three components) which was recrystallised from benzene to give colourless crystals. Yield 3.1g (12%). p 144-145°C (lit 144-145 β C). The identity of the product was confirmed as above. ]_ς Note; The low yield was probably due to insufficient reaction time or too low a temperature being used as glc analysis of the crude product revealed the presence of starting material and what is suspected to be

3-broτ_ιcbenz-onitrile.

A solution of 4-pentylphenylboronic acid (B13 ) (2.88g, 0.015 mol) in ethanol (50 ml) was added dropwise to a stirred mixture of 2,5- dibromobenzonitrile (1.40g, 5.36 mol) and tetrakis-(triphenylphosphine) palladiuπ(θ) (0.3749g, 0.325 mmol) in benzene (30 ml) and 2M-sodium carbonate (30 ml) at room temperature under dry nitrogen. The stirred mixture was heated under reflux (90-95°C) for 18h (ie until glc analysis revealed absence of starting material), cooled and stirred for lhr " at room temperature with 30% hydrogen peroxide (5 ml). The mixture was

^3 filtered, the filtrate was washed with ether (twice), and the combined ethereal phases were washed with water and dried (MgSO ). The solvent was removed in vacuo and the residue was purified by column chromato¬ graphy [silica gel/petroleum fraction (bp 40-60°C) - dichlorpmethane, 2tl] to give a colourless solid which was recrystallised from ethanol

35 to yield fine colourless crystals. Yield 1.13g (53%). The identity of the product was confirmed as above. The product showed the following liquid crystal transitions ( C): K-I 40.0, S A -N (33.5), N-I (38.0)

A solution of 4-hexoxyphenylboronic acid ( B 22 ) (3.33g, 0.015 mol) in ethanol (70 ml) was added dropwise to a stirred mixture of 2,5-dibromobenzonitrile (1.30g, 4.98 mmol) and tetrakis-(triphenyl- phosphine) palladium (0) (0.3554g, 0.308 mmol) in benzene (30 ml) and 2M-sodium carbonate (30 ml) at room temperature under dry nitrogen. The stirred mixture was heated under reflux (90-95°C) for 21h (ie until glc analysis revealed absence of starting material), cooled and stirred for lhr at room temperature with 30% hydrogen peroxide (5 ml). The mixture was filtered, the filtrate was washed with ether (twice), and the combined ethereal phases were washed with water and dried (MgSO ). The solvent was removed in vacuo and the residue was purified by column chromatography [silica gel/petroleun fraction (bp 40-60°C)-dichloromethane, 2T1] to give a colourless solid which was recrystallised from ethanol to give colourless crystals. Yield 0.87g (38%).

Route A2 The 4-alkyl-and 4-alkoxy-phenylboronic acids prepared using route B exemplified above were used to prepare compounds of formula 1.1 via route A 2.

N-Bromosuccinimide (NBS) (37.71g, 0.21 mol) was added in small portions over a 40 mins to a stirred, cooled (-10-0°C) solution of 2-aminobenzonitrile (25.00g, 0.21 mol) in dry dichloromethane (150 ml) under dry nitrogen. The mixture was stirred at 0°C for 1 h 10 mins (glc analysis revealed a complete reaction) and washed with a large amount of water. The aqueous layer was washed with dichloromethane and the combined organic phases were washed with water and dried (MgS04). The solvent was removed in vacuo to give a red/purple solid (39g, 94%) mp = 92-94°C.

A stirred mixture of 2-amino-5-bromobenzonitrile (25.00g 0.13 mol) and 36% (cone) HC1 (110 ml) was gently warmed to obtain a solution, then cooled to -5°C and a solution of sodium nitrite (10.50g, 0.15 mol) in water (50 ml) was added dropwise whilst maintaining the tempeature at -5°C. The mixture was stirred at 0°C for hr, cyclohexane was added, and a solution of potassium iodide (43.5g, 0.26 mol) was added dropwise at between 5 and 10°C. The mixture was stirred at room temperature for a few hours (or overnight for convenience), then warmed gently for 10 mins to ensure complete reaction. The product was extracted into ether (twice), the combined ethereal phases were washed successively with sodium metabisulphite, 10% sodium hydroxide, water and dried (Mg S04). The solvent was removed in vacuo to give a sand-coloured solid (35g, 87%). mp = 113-114°C

A solution of 4-hexoxyphenylboronic acid ( see step B22) ( I.56 g, 7.03 mmol) in ethanol (minimum amount possible ___ 20 ml) was

added dropwise to a stirred mixture of 5-bromo-2-iodobenzonitrile

(1.80g, 5.84 mmol) and tetrakis (triphenylphosphine) palladium (0)

(abbreviated hereinafter to TTP) (0.35 72g, 0.31 mmol) in benzene

(30 ml) and 2M-sodium carbonate (30 ml). The stirred mixture was heated under reflux ( 95 ~ ) £or ~ - ~~ hr (ie until glc analysis revealed a satisfactory starting material - product ratio (1:10)). The product was extracted into ether (twice), the combined ethereal extracts were washed with brine and dried (MgSO ). The solvent was removed jLn vacuo and the residue was purified by column chromatography (silica gel/ petroleum fraction (bp 40-60°C) - dichloromethane, l:l) to give a colourless solid (1.72g, 82%). _

CN

(2) G 8 H 17 0-^-^>-Br

5-bromo-2-iodobenzonitrile 2.50g, 8.12 mmol

4-octoxyphenylboronic acid (via route E2) 2.44g, 9.76 mmol TTP 0.4927g 0.43 mmol

The method was the same as that above. The mixture was reheated under reflux (95°C) for 2 h. Purified by column chromatography [silica gel/petroleum fraction (bp 48-60°C) -dichloromethane, 1:1] to give a colourless solid (2.50g, 80%).

CN

(3) C^-^-^-Br

5-bromo-2-iodobenzonitrile 3.50g, 0.001 mol

4-pentylphenylboronic acid (route Bl) 2.53g, 0.013 mol

TTP 0.6421g, 0.56 mmol s The method was the same as that above. The mixture was heated under reflux (295°C) for 2 h. Purified by column chromatography ( silica gel/petroleum fraction (bp 40-60°C)-dichloromethane, l:l) and iistillatior (Kugel rohr. 0.1 mm Hg) to give a pale yellow liquid

( V.- ι. £C. a s-, 7■ + jo)) .. CN

4-bromo-2-cyano-4 1 -pentylbiphenyl (A 3(3 0.34g, 1.0 mmol 4-hexoxyphenylboronic acid (B22) 0.44g, 1.98 mmol

TTP 0.1645g, 0.14 mmol

4-bromo-2-cyano-4l-hexoxybiphenyl ( A23(l)) 1.50g, 4.19 mmol 4-pentylphenylboronic acid (B13) 1.05g, 5.47 mmol TTP 0.314g, 0.27 mmol

0

4-bromo-2-cyano--4 1 -pentylbiphenyl (A23(3)) 1.30g, 3.96 mmol

4-octoxypenylboronic acid (via route B22) 1.19g, 4.76 mmol

TTP 0.265g, 0.23 mmol

4-bromo-2-cyano-4l-octoxybiphenyl (from A23(2)l.48g, 3.83 mmol 4-pentylphenylboronic acid (from B13) l.Olg, 5.26 mmol

TTP

0.2812g, 0.34 mmol 0

In each case the method used was that of step A2 above. The mixture in case (2) was heated unier reflux for 17 hours, in cases (l) and (3) ^or 21 hours, and case (4) for 22 hours, ie until glc analysis revealed a complete reaction. The product was purified by -" column chromatography (silica gel / petroleum fraction (bp 40 - 60) - dichloromethane l:l) to afford solids which were recrystallised from ethanol. The product of (2) was pale yellow and so was -ecolour- ised with charcoal.

Yields: (l) colourless crystals (0.26 g, 6l %) ° (2) colourless plates (O.Bo g, 4^ yi)

(3) colourless crystals (l.l8 g, 66 %)

(4) colouless solid (1.16 g, 67 %)

Example 2

Using route Cl the following compounds of structure 1.3 were

10

2-hydroxybenzonitrile A 7.50g, 0.063 mol

B 8.10g, 0.068 mol

1-bromo-octane A 14.00g, 0.127 mol , 1-bromohexane B 13.50g, 0.082 mol Potassium Carbonate A 17.50g 0.127 mol

B 18.77g 0.136 mol The experimental procedure was the same as for Step B21 described above. Yield: A 13.90g (96%) bp 130-135° at 0.05mm Hg; B 13-llg (95%) bp 115-118° at 0.1 mm Hg.

Bromine A 18.70g, 0.117 mol

B 19.32g 0.12 mol Cll product A 13.50g, 0.058 mol B 12.25g, 0.060 mol The bromine was added dropwise during 15 minutes to a stirred solution of the Cll product in chloroform (30 ml) at room temperature. The stirred solution was refluxed for 42 hours (glc showed a complete

reaction) . The cooled solution was washed with sodium meta- bisulphite, water, then dried (Mg SO ) . The solvent was removed in vacuo in give an off-white solid. Yield: A 17.50g (97%) mp 36-37°, B 16.10g (95%) low melting around 15°. Step C13

4'-bromo - 4 - pentylbiphenyl 9.35g magnesium 0.871g tri-isopropyl borate 11.66g

The experimental procedure was the same as for steps B13 and B22. The crude yield was 8.29g, 100%.

(A) C12 product (A) 1.55g, 5.00 mmol C13 product 1.75g, 6.53 mmol TPP 0.38g, 0.33 mmol

(B) C12 product (B) 1.55g, 5.50 mmol C13 product 1.91g, 7.13 mmol TTP 0.39g, 0.34 mmol The experimental procedure was the same as for Step A23 above. The crude product was purified by column chromatography (silica gel/ petroleum fraction (bp 40-60°) dichloromethane 2:1) to give a colour¬ less solid which was recrystallised from ethanol-ethylacetate (2:1) to yield colourless crystals. Yield: A 1.85g (82%), B 1.10g (47%). Example 3

Using route El the compound of structure 1.10:

was prepared. Liquid crystal transitions were K 48.0 S 118.0 I.

tep Ell

'-bromo-2-fluro-4-pentylbiphenyl 9.90g

Magnesium 0.871g

Triisopropylborate 11.66g

The experimental procedure was the same as for Step B13 above. Crude yield: 8.85g, 100%. Step E12

5-bromo-2-octoxybenzonitrile (C12 ) 1.30g, 4-19 mmol

Ell product 1.56g, 5.45 mmol

TTP 0.28g, 0.24 mol

The experimental procedure was the same as for step A23 above. The crude product was purified by column chromatography (silica gel/ petroleum fraction (bp 40-60°) dichloromethane 2:1) to give a colourless solid which was recrystallised from ethanol to give colourless crystals. Example 4

Using route D2 the following compounds of structure 1.4 was pre¬ pared: ΛΓVΓ J?

* The extrapolated dielectric anis ropy &E of the compound li s measured to be - 9.5.

Step D21

(A) 4-bromo-3-fluorophenol 6.00g 1-bromo-octane 7.30g potassium carbonate lO.OOg

(B) 4-bromo-3-fluorophenol lO.OOg 0 1-bromohexane 10.37g potassium carbonate 14.50g The experimental procedure was the same as for Step B21 above. Yields: A 9.01g, 96% as a colourless liquid bp 140-142° at 0.5 mm Hg; B 13.71g, 96%. 15 Step D22

20 (A) Step D21 product 2.00g, 6.60 mmol

Step C13 product 2.30g, 8.58 mmol

TTP 0.60g, 0.52 mmol

(B) Step D21 product 1.50g, 5.45 mmol

Step C13 product 1.90g, 7.10 mmol

~5 TTP 0.50g 0.43 mmol

The experimental procedure was the same as for Step A23 above. The crude products were purified by column chromatography (silica " gel/petroleum fraction (bp 40-60°) dichloromethane, 3:1) to yield colourless solids which were recrystallised from ethanol-ethyl acetate ~° (2:1) to yield colourless crystals. Yield: A 2.30g, 78%; B 1.46g, 64%.

These products showed liquid crystal phases as below:

(A) K 69.0 ( S 25.0 S 43.0 ) S 119.0 N 158.0 I

K J C

(B ) K 83.5 ( S 48.5 S 62.0 ) S 105.0 N 166.0 I

K J C

~ ~ \

(A) Step D22 product 1.50g, 3.36 mmol n-butyl lithium 0.50 ml 10.OM in hexane, 5.00 mmol

(B) Step D22 product 1.25g, 2/99 mmol n-butyl lithium 1.20 ml 2.5M in hexane, 3.00 mmol τ e soloution of n-butyl lithium was added dropwise to the solution of the appropriate D22 product in dry THF (80 ml) under dry nitrogen with stirring, cooled to -78°C. In the case of (A) the mixture was maintained under these conditions for 6 hours, and for (B) for 5 hours. The mixture was then poured into a solid CO /ether slurry. 10% hydrochloric acid was added, the aqueous layer was washed with ether and the combined ethereal.extracts were washed with water and dried (Mg S0„) The solvent was removed in vacuo to give

4 colourless solids. Yields: (A) l-65g, (B) 1.45g (tic analysis revealed the presence of some starting materials). Step D24

(A) Step D23 product 1.65g 3.37 mmol oxalyl chloride l.OOg 7.87 mmol 35% ammonia 30 ml

DMF 8 drops thionyl chloride 4.10g, 0.034 mol

(B) Step D23 product 1.45g 3.14 mmol oxalyl chloride 0.80g 6.30 mmol 35% ammonia 25 ml

DMF 2 drops thionyl chloride 3.70g, 0.03 mol

A solution of the oxalyl chloride in dry benzene (30 ml) was added dropwise to a stirred solution of the Step D23 product and DMF in dry

benzene (30 ml) at room temperature. The mixture was stirred at room temperature overnight and the excess of oxalyl chloride and benzene were removed in vacuo. The residue was dissolved in diglyme (10 ml) and added dropwise to the gently stirred 35% ammonia, the resulting precipitate was filtered off and dried (Ca Cl ) in vacuo (0.1 mm Hg) to give a colourless solid. A solution of the thionyl chloride in dry DMF (30 ml) was added dropwise to a stirred sollution of this solid in dry DMF (30 ml). The mixture was stirred at room temeprature overnight and poured onto ice/water. The product was extracted into 0 ether (twice), the combined ethereal extracts were washed with water, sodium hydrogen carbonate, water and dried (MgSO ). The solvent was removed in vacuo and the residue was purified by column chromatography [silica gel/petroleum fraction (bp 40-60°C) - dichloromethane, 2:1] to give a colourless solid. In the case of (A) this was recrystallised 5 from ethyl acetate, and (B) from ethanol-ethyl acetate (2:1) to yield colourless crystals. Yield A: 0.21g, 13% based on D22 product; B 0.20g, 15% based on D22 product. Examples of Liquid Crystal Mixtures Example 5 0 Properties of mixtures of two cyano-terphenyls of formula 1.1,

1 2 1 ie (A) where both R and R are n-pentyl, and (B) where both R and

2

R are n-hexyloxy, with an FTP of formula:

are listed below together with properties of the pure FTP.

"- '

~ e

Example 5 ( cont . )

-.

From these results it is clear that the mixing of a cyanoterphenyl of the invention with an FTP suppresses the S phase of the FTP, in

B some cases lowers the temperature at which the S phase of the FTP appears on heating, and in others broadens the temperature range over which the S phase persists.

In the following examples the following mixtures and compounds are referred to by the abbreviations indicated: Mixture HI p

(ie a mixture of FTP's of formula IIA (Y = - 7? ) described above)

This mixtures shows liquid crystal transition temperatures;

K 31.8 S 40.4 S 50.6 S„ 107 N 160 I ? ?? C

Mixture H2 __

-C 6 Ki3 c -©-<@-<2>- C 5 H ιι- n 13.6 wt

F

(ie a mixture of FTT' cf formula IIB and IIC described above) This mixture shows liquid crystal transition temperatures:

< 20 Sc 96.9 N 146.2 I Mixture H3

(ie a mixture of compounds of formula IIIA)

This mixture shows liquid crystal transition temperatures \ S, 41.5 Sc 87 S 120.7 N 134.5 I

Dopant 1

CN

•CH.

D-C 8 H 17 O-(O 200CHCH Dopant 2.

C ,

( ie formula VII described above) Example 6

Mixture HI + 10%

K 13 Sc 88.4 N 134.3 I Addition of the cyanoterphenyl results in increased Sc range and elimination of low temperature undesirable smectic phases relative to pure Hi. Example 7

Mixture HI + 10%

K 16.5 Sc 96.4 N 153 I

Increased Sc range, elimination of lower smectic phases.

Example 8

Mixture H3 + 10% <-20 Sc 66 SA 106.6 N 124 I

Supercooled to much lower temperature than pure H3, no lower smectic phases.

Example 9

Mixture H2 72 wt%

GN F

Dopant 1 6.25 wt % Dopant 2 3.75 wt % < 20 Sc 90 S 124 N 133 I

This mixture shows a room temperature Sc phase, with a higher temeprature S phase which assists alignment in a liquid crystal device. Switching response time (usec) at various peak voltages with zero volts AC bias at 30°C, and spontaneous, polarisation Ps at various temperatures using a 2 μm polyimide aligned cell are tabulated below:

Peak voltage Resp. time Temp (v) (°C) (nC/c )

10 205 80 2.0 15 99 70 4.5 20 63 60 6.7 25 46 50 8.1 30 38 40 9.3 35 31 40 9.3 40 27 30 10.5 45 23 50 21 55 19 60 17 65 16

At 30°C the cone angle was found to be 23°. Example 10

Mixture H2 72 wt %

Dopant 1 5.8 wt %

Dopant 2 4.2 wt % * 20 Sc 91.5 SA 123.7 N 133.7 I Switching response times (μsec) at various AC bias voltages, at 30°C using a 1.9 μm polyimide aligned cell are tabulated below. The cone angle was 23°.

(Contd... )

Using a 6 μm polyimide aligned cell the Ps at various tem¬ peratures was measured and tabulated below.

Example 11 (comparative)

To illustrate the advantages of use of the terphenyls of the invention in liquid crystal materials two mixtures were prepared containing mixture H2 without a terphenyl of the invention, and proportions of dopants 1 and 2 the same as or very close to those used in the mixtures of examples 9 and 10, identified as mixtures 9A and 10A below.

Hence these two mixtures retain their useful Sc phase up to virtually the same temperature as the mixtures of Examples 9 and 10 respectively.

At 30°C mixtures 9A and 10A showed the following Ps and minimum switching response times (T min) (γ. sec) at the voltage (Vmin) and AC bias shown, the corresponding values for mixtures 9 and 10 being given for comparison.

From this table it can be seen that mixtures 9 and 10, which contain a terphenyl of the invention, have a higher Ps and faster switching times than the corresponding mixtures 9A and 10A which 0 lack such a terphenyl.

An example of the use of a compound of Formula I in a liquid crystal material and device embodying the present invention will now be described with reference to the accompanying drawing, Figure 12 ~ which is a cross sectional end view of a liquid crystal shutter.

In Figure 12a liquid crystal cell comprises a layer i of liquid crystal material exhibiting a nematic or chiral smectic C phase, between a glass slide 2 having a transparent conducting layer 3 on its surface, eg of tin oxide or indium oxide, and a glass slide 0 having a transparent conducting layer 5 on its surface. The slides 2,4 bearing the layers 3, 5are respectively coated by films 6, 7 of a polyimide polymer. Prior to construction of the cell the films 6 and 7 are rubbed with a soft tissue in a given direction the rubbing directions being arranged parallel upon construction of the cell. A spacer 8 eg of polymethylmethacrylate, separates the slides 2, to the required distance, eg 5 microns. The liquid crystal material :l is introduced between the sliαes 24 by filling the space between the slides 2, 4 and spacer 8 and sealing the spacer Q in a vacuum in a known way.

~.r\ Suitable materials for the layer 1 of li uid crystal material are the mixtures of examples 9 and 10 above, with a spacing between the films 6 and of about 2 urn.