JP5397710B2 - New alkenylbiphenyl derivatives - Google Patents

Description

  The present invention relates to an alkenylbiphenyl derivative which is a novel liquid crystal compound and a liquid crystal composition containing the same. These are useful as materials for electro-optical liquid crystal display, particularly nematic liquid crystal display.

  Liquid crystal display elements are used in various measuring instruments, automobile panels, word processors, electronic notebooks, printers, computers, televisions, etc., including watches and calculators. Typical liquid crystal display methods include TN (twisted nematic), STN (super twisted nematic), DS (dynamic light scattering), GH (guest / host), or FLC (ferroelectric liquid crystal). In addition, as a driving method, a multiplex drive is generally used instead of a conventional static drive, and a simple matrix method and recently an active matrix method have been put into practical use.

  Various characteristics are required as a liquid crystal material according to these display methods and driving methods. Among them, high-speed response and a wide temperature range are very important in common in most cases.

  The physical properties required of the liquid crystal material in order to speed up the response are directly (i) reducing the viscosity or (ii) increasing the elastic constant. However, when the elastic constant is increased, the threshold voltage often increases. Therefore, when low voltage driving is required, it is necessary to reduce the viscosity without increasing the elastic constant.

  In order to obtain a liquid crystal material exhibiting a wide temperature range, it is necessary to add a compound having a high nematic phase upper limit temperature (TN-I). However, compounds with low viscosity generally have low liquid crystallinity, and compounds with excellent liquid crystallinity often have high viscosity. Therefore, when trying to obtain a liquid crystal composition having a wide liquid crystal phase temperature range up to a high temperature range, the viscosity is also low. There was a tendency to grow.

  In view of the above, in order to prepare a liquid crystal composition having a wide temperature range and capable of high-speed response, a liquid crystal compound having a high nematic phase upper limit temperature (TN-I) and a low viscosity is required. I understand that.

  Currently, liquid crystal compounds that satisfy these conditions relatively well include, for example, general formulas (IIa) and (IIb)

In the formula, Ra and Rb each represent a linear alkyl group, and Rc represents a linear alkenyl group. However, even if these are used, it is difficult to meet the demand for improving the characteristics of the liquid crystal material accompanying the improvement in display quality, and a liquid crystal compound having further excellent characteristics is desired.

  In liquid crystal compounds, it is known that the above effects (decrease in viscosity, increase in TN-I) may be obtained by using an alkenyl group having a double bond introduced in place of the side chain alkyl group. ing. However, most of the alkenyl groups in this case are directly bonded to the cyclohexane ring as in the compound of the general formula (IIb), and the alkenyl group (particularly the 3-alkenyl group) is directly bonded to the benzene ring of the biphenyl group. In fact, it is not easy to introduce an alkenyl group into the skeleton of such a compound, and it is a fact that no specific compound has been known so far.

  By the way, the alkenylbiphenyl derivative of the general formula (I) of the present invention is a novel compound as described above. However, in theory, the general formula itself that can include the general formula (I) is not without examples.

  Patent Document 1 includes a general formula (V) including a large number of compounds containing an alkenyl group or an alkenyloxy group as a side chain.

It is shown. The range represented by the general formula (V) is very wide, and depending on the selection of R ¹ , B, m, A and R ² , the compound represented by the general formula (I) of the present invention is included. .

  However, in all the specific compounds shown in this publication, the alkenyl group is directly connected to the cyclohexane ring (or dioxane ring), and the alkenyl group is bonded to the benzene ring as in the compound of the general formula (I) in the present invention. A directly connected compound, that is, a compound in the case where ring B represents a 1,4-phenylene group in the general formula (V) is not described at all.

  Furthermore, this publication does not describe even a general synthesis method for a compound in the case where ring B represents a 1,4-phenylene group. According to this publication, a Wittig reagent prepared from a methoxymethyltriphenylphosphonium salt is reacted with an aldehyde to synthesize an aldehyde having an extended carbon chain, and this is reacted with an alkyl Wittig reagent to give 1- An alkenyl group other than an alkenyl group is introduced. However, even if this method is applied to a compound in which the 3-butenyl group is directly bonded to the benzene ring, such as the compound of the general formula (I) of the present invention, the synthesis of the intermediate is difficult because hydrolysis does not proceed easily. It is.

  As described above, it is difficult to say that the compound of the general formula (I) of the present invention has been disclosed by this publication.

  On the other hand, there is also a disclosure of a cyclohexyl alkenyl biphenyl derivative (see Patent Document 2) or a terphenyl derivative having an alkenyl group (see Patent Document 3). However, these literature disclosures do not suggest compounds for the present invention.

JP 61-83136 A Japanese Patent Application Laid-Open No. 61-27929 (Example) British Patent Application No. 2281656

  The problem to be solved by the present invention is to provide a novel alkenylbiphenyl derivative as a liquid crystalline compound having a high TN-I and a low viscosity as a tricyclic compound in order to meet the above-mentioned purpose. An object of the present invention is to provide a liquid crystal composition having a low viscosity and a wide liquid crystal temperature range.

In order to solve the above problems, the present invention
1. Formula (I)

(Wherein R represents an alkyl group having 1 to 12 carbon atoms, ring A represents a 1,4-phenylene group or trans-1,4-cyclohexylene group optionally substituted with fluorine, and ring B represents Represents a 1,4-phenylene group optionally substituted with fluorine, R ′ represents hydrogen or an alkyl group having 1 to 5 carbon atoms, and when R ′ is an alkyl group, the double bond represents a cis ( Z) or trans (E))).
2. 2. The alkenylbiphenyl derivative according to 1 above, wherein R ′ represents a hydrogen atom in the general formula (I).
3. 3. The alkenylbiphenyl derivative according to 1 or 2 above, wherein in general formula (I), ring A represents a trans-1,4-cyclohexylene group and ring B represents a 1,4-phenylene group.
4). 4. A liquid crystal composition containing the alkenylbiphenyl derivative according to the above 1, 2 or 3.
5. 5. A display device using the liquid crystal composition according to 4 above.
Has been found as means for solving the above problems.

  The alkenylbiphenyl derivative provided by the present invention can be easily produced industrially as shown in Examples. The obtained alkenylbiphenyl derivative has a higher nematic phase upper limit temperature and is superior in improving the responsiveness compared to a tricyclic biphenyl derivative compound having a similar or similar skeleton, which is conventionally used. The liquid crystal composition is extremely useful as a practical liquid crystal, particularly for a liquid crystal display having a wide temperature range and requiring a high-speed response.

  An example of the present invention will be described below. In the general formula (I), R represents an alkyl group having 1 to 12 carbon atoms, and a linear alkyl group having 1 to 7 carbon atoms is preferable. Ring A represents a 1,4-phenylene group or trans-1,4-cyclohexylene group which may be fluorine-substituted, but a 2-fluoro-1,4-phenylene group or trans-1,4-cyclohexylene group Are preferred, and a trans-1,4-cyclohexylene group is particularly preferred. Ring B represents a 1,4-phenylene group which may be substituted with fluorine, and a 1,4-phenylene group, a 3-fluoro-1,4-phenylene group or a 2-fluoro-1,4-phenylene group is preferred. A 1,4-phenylene group is particularly preferred. R 'represents hydrogen or an alkyl group having 1 to 5 carbon atoms, but if the side chain becomes too long, the viscosity increases, so hydrogen or a methyl group is preferable, and a hydrogen atom is particularly preferable. When R ′ is an alkyl group, the configuration of the double bond is cis (Z) or trans (E), but trans (E) is preferred.

  Accordingly, among the compounds represented by the general formula (I), the following general formulas (Ia) to (Id) are preferable.

(In the formula, R ¹ represents an alkyl group having 1 to 12 carbon atoms.) Among these general formulas (Ia) to (Id), the compound represented by the general formula (Ia) is particularly preferable.
The compound of the general formula (I) of the present invention can be produced as follows.

  That is, the general formula (IIIa)

And an organic metal reactant represented by the general formula (IVb)

It can manufacture by making the compound represented by these react in presence of a catalyst. In the above formula, X represents Li, MgBr, MgI or MgCl, with MgBr or MgI being preferred. Y represents a leaving group such as a bromine atom, an iodine atom, a chlorine atom, a p-toluenesulfonyl group, a methanesulfonyl group or a trifluoromethanesulfonyl group, preferably a bromine atom or an iodine atom. R, ring A, ring B and R ′ have the same meaning as in general formula (I).

As the catalyst, a palladium (0) complex, a palladium (II) complex or a nickel (II) complex is preferable, and a palladium (0) complex is particularly preferable.
Alternatively, the compound of the general formula (I) is a compound of the general formula (IIIb)

And a compound of the general formula (IVa)

It can manufacture also by making it react similarly with the organometallic reagent represented by these. Here, in the above formula, X, Y, R, ring A, ring B and R ′ represent the same meaning as described above.

  Table 1 lists the phase transition temperatures of representative compounds of the compound of the present invention thus produced represented by the general formula (I).

(In the table, Cr represents a crystalline phase, SB represents a smectic B phase, N represents a nematic phase, I represents an isotropic liquid phase, and the phase transition temperature is “° C.”.) The excellent effects obtained by adding it to the liquid crystal composition are as follows.
Of the compounds represented by the general formula (I), those shown in Table 1, wherein ring A represents a trans-1,4-cyclohexylene group, ring B represents a 1,4-phenylene group, and R ′ = H A representative formula (I-1)

20% by weight of the compound and a host liquid crystal composition (M)

A liquid crystal composition (M-1) comprising 80% by weight was prepared. Here, the physical property values of (M) are as follows.
TN-I: 116.7 ° C
Response time (τr = τd): 25.3 ms Refractive index anisotropy (Δn): 0.090
Here, the response time is a measured value at the time of voltage application at which the rise time (τr) and the fall time (τd) become equal at 20 ° C.

On the other hand, the physical property values of (M-1) were as follows.
TN-I: 128.6 ° C
Response time (τr = τd): 21.0 ms Refractive index anisotropy (Δn): 0.108
As described above, it can be seen that the response time is shortened by about 20% even though the TN-I has increased by about 12 °.

  On the other hand, the compound represented by the formula (IIa-1) represented by the formula (IIa) having a cyclohexylbiphenyl skeleton similarly to the formula (I) but having both side chains of a linear alkyl group.

The physical properties of the composition (Ma-1) comprising 20% by weight of the above compound and 80% by weight of the host liquid crystal were as follows.
TN-I: 125.5 ° C
Response time (τr = τd): 22.5 ms Refractive index anisotropy (Δn): 0.105
Therefore, although both the response time and the nematic phase upper limit temperature (TN-I) are improved for the host liquid crystal (M), when compared with the physical property value of (M-1), (TN-I) is It can be seen that the response has been delayed by about 7% despite being about 3 ° lower.

  Next, formulas (IIb-1) and (IIb-2) represented by general formula (IIb) having the same skeleton and having a structure in which an alkenyl group is directly connected to a cyclohexane ring

Was used to prepare a composition. Composition (Mb-1) comprising 20% by weight of the compound of formula (IIb-1) and 80% by weight of the host liquid crystal (M), 20% by weight of the compound of formula (IIb-2) and 80% by weight of the host liquid crystal (M) The physical properties of the composition consisting of (Mb-2) were as follows.
(Mb-1)
TN-I: 122.5 ° C
Response time (τr = τd): 22.1 ms Refractive index anisotropy (Δn): 0.109
(Mb-2)
TN-I: 128.5 ° C
Response time (τr = τd): 21.8 ms Refractive index anisotropy (Δn): 0.110
Accordingly, although the response time is improved for the host liquid crystal (M) and the aforementioned (Ma-1), the response becomes slow when compared with the physical property value of (M-1) of the present invention. You can see that

  Therefore, the compound of (I-1) of the present invention has (IIa-1), (IIb-1) or (IIb) in obtaining a liquid crystal composition having low viscosity, excellent responsiveness and a wide nematic phase temperature range. It is clear that an effect superior to the compound of -2) is exhibited.

  Therefore, the compound of the general formula (I) of the present invention is in a mixture with other nematic liquid crystal compounds and used for a field effect display cell such as a TN type or STN type, particularly as a material having a low viscosity and a fast response. It can be preferably used. In addition, since the compound of the general formula (I) does not have a strong polar group in the molecule, it is easy to obtain a large specific resistance and a high voltage holding ratio, and it should be used as a constituent component of an active matrix driving liquid crystal material. Is also possible. The present invention also provides a liquid crystal composition containing at least one compound represented by the general formula (I) as a constituent component.

  In this composition, preferable representative examples of the nematic liquid crystal compound that can be used by mixing with the compound of the general formula (I) include, for example, 4-substituted benzoic acid 4-substituted phenyl, 4-substituted cyclohexanecarboxylic acid 4-substituted phenyl, 4-substituted cyclohexanecarboxylic acid 4′-substituted biphenylyl, 4- (4-substituted cyclohexanecarbonyloxy) benzoic acid 4-substituted phenyl, 4- (4-substituted cyclohexyl) benzoic acid 4-substituted phenyl, 4 -(4-substituted cyclohexyl) benzoic acid 4-substituted cyclohexyl, 4,4'-substituted biphenyl, 1- (4-substituted cyclohexyl) -4-substituted benzene, 4,4'-substituted bicyclohexane, 1- [2- (4-Substituted cyclohexyl) ethyl] -4-substituted benzene, 1- (4-substituted cyclohexyl) -2- ( -Substituted cyclohexyl) ethane, 4,4 "-substituted terphenyl, 4- (4-substituted cyclohexyl) -4'-substituted biphenyl, 4- [2- (4-substituted cyclohexyl) ethyl] -4'-substituted biphenyl, 4- (4-substituted phenyl) -4'-substituted bicyclohexane, 4- [2- (4-substituted cyclohexyl) ethyl] -4'-substituted biphenyl, 4- [2- (4-substituted cyclohexyl) ethyl] cyclohexyl -4'-substituted benzene, 4- [2- (4-substituted phenyl) ethyl] -4'-substituted bicyclohexane, 1- (4-substituted phenylethynyl) -4-substituted benzene, 1- (4-substituted phenyl) Ethynyl) -4- (4-substituted cyclohexyl) benzene, 2- (4-substituted phenyl) -5-substituted pyrimidine, 2- (4′-substituted biphenylyl) -5-substituted phenyl Benzene ring in spermidine and each compound can be exemplified compounds having a lateral substituent.

  Among these, for active matrix driving, 4,4′-substituted biphenyl, 1- (4-substituted cyclohexyl) -4-substituted benzene, 4,4′-substituted bicyclohexane, 1- [2- (4-substituted cyclohexyl) Ethyl] -4-substituted benzene, 1- (4-substituted cyclohexyl) -2- (4-substituted cyclohexyl) ethane, 4,4 "-substituted terphenyl, 4- (4-substituted cyclohexyl) -4'-substituted biphenyl 4- [2- (4-substituted cyclohexyl) ethyl] -4′-substituted biphenyl, 4- (4-substituted phenyl) -4′-substituted bicyclohexane, 4- [2- (4-substituted cyclohexyl) ethyl] -4'-substituted biphenyl, 4- [2- (4-substituted cyclohexyl) ethyl] cyclohexyl-4'-substituted benzene, 4- [2- (4-substituted phenyl) Ethyl] -4′-substituted bicyclohexane, 1- (4-substituted phenylethynyl) -4-substituted benzene, 1- (4-substituted phenylethynyl) -4- (4-substituted cyclohexyl) benzene and the above benzene ring Fluorine substituted compounds are suitable.

The following examples further illustrate the present invention. However, the present invention is not limited to these examples.
The structure of the compound was confirmed by nuclear magnetic resonance spectrum (NMR), mass spectrum (MS) and infrared absorption spectrum (IR). Further, “%” of the composition represents “% by weight”.
Reference Example 1 Synthesis of 4- (trans-4-propylcyclohexyl) -4 ′-(3-butenyl) biphenyl (No. (I-1) compound in Table 1)

A solution of 7.2 g of 4-bromo-1- (3-butenyl) benzene in 30 mL of tetrahydrofuran (THF) was added dropwise to 0.83 g of magnesium at a rate at which reflux of the solvent was gently maintained. After completion of dropping, the mixture was further heated to reflux for 1 hour and cooled to room temperature. The obtained Grignard reactant was added dropwise at 40 ° C. or lower to a solution of 1- (trans-4-propylcyclohexyl) -4-iodobenzene 9.3 g and tetrakistriphenylphosphine palladium (0) 330 mg in THF 40 mL over 1 hour. For 1 hour. Water and 10% hydrochloric acid were added, and the aqueous layer was separated and extracted with toluene. The organic layers were combined and washed with 10% hydrochloric acid, water and then saturated brine. After dehydrating and drying over anhydrous sodium sulfate, the solvent was distilled off to obtain 12.6 g of 4- (trans-4-propylcyclohexyl) -4 '-(3-butenyl) biphenyl crude crystals. This was purified using silica gel column chromatography (hexane), and further recrystallized from ethanol to obtain 8.0 g of a purified product. This compound showed a crystalline phase at room temperature, its melting point was 147 ° C., showed a smectic B (SB) phase up to 149.5 ° C., and a nematic (N) phase up to 214 ° C.

Similarly, the following compounds were obtained.
4- (trans-4-methylcyclohexyl) -4 '-(3-butenyl) biphenyl 4- (trans-4-ethylcyclohexyl) -4'-(3-butenyl) biphenyl 4- (trans-4-butylcyclohexyl) -4 '-(3-butenyl) biphenyl 4- (trans-4-pentylcyclohexyl) -4'-(3-butenyl) biphenyl 4- (trans-4-heptylcyclohexyl) -4 '-(3-butenyl) biphenyl 3-Fluoro-4- (trans-4-methylcyclohexyl) -4 ′-(3-butenyl) biphenyl 3-fluoro-4- (trans-4-ethylcyclohexyl) -4 ′-(3-butenyl) biphenyl 3- Fluoro-4- (trans-4-propylcyclohexyl) -4 '-(3-butenyl) biphenyl 3-fluoro-4- ( Lance-4-butylcyclohexyl) -4 '-(3-butenyl) biphenyl 3-fluoro-4- (trans-4-pentylcyclohexyl) -4'-(3-butenyl) biphenyl 3-fluoro-4- (trans- 4-Heptylcyclohexyl) -4 '-(3-butenyl) biphenyl (Example 1) Synthesis of 2-fluoro-4-propyl-4 "-(3-butenyl) terphenyl In Reference Example 1, 1- (trans- The title compound was obtained in the same manner except that 2-fluoro-4-propyl-4′-iodobiphenyl was used instead of 4-propylcyclohexyl) -4-iodobenzene.
Similarly, the following compounds were obtained.
2-Fluoro-4-methyl-4 "-(3-butenyl) terphenyl 2-fluoro-4-ethyl-4"-(3-butenyl) terphenyl 2-fluoro-4-butyl-4 "-(3- Butenyl) terphenyl 2-fluoro-4-pentyl-4 "-(3-butenyl) terphenyl 2-fluoro-4-heptyl-4"-(3-butenyl) terphenyl 2'-fluoro-4-methyl- 4 ″-(3-butenyl) terphenyl 2′-fluoro-4-ethyl-4 ″-(3-butenyl) terphenyl 2′-fluoro-4-propyl-4 ″-(3-butenyl) ter Phenyl 2′-fluoro-4-butyl-4 ″-(3-butenyl) terphenyl 2′-fluoro-4-pentyl-4 ″-(3-butenyl) terphenyl 2′-fluoro-4-heptyl- 4 ″-(3-butenyl) terphenyl ( Preparation of Reference Example 2) The liquid crystal composition (1)
General-purpose host liquid crystal (M)

Was prepared. This host liquid crystal (M) exhibits a nematic phase at 116.7 ° C. or lower. The response time and refractive index anisotropy (Δn) of this composition were as follows.
Response time (τr = τd): 25.3 ms Refractive index anisotropy (Δn): 0.090
Here, the response time is a measured value at the time of voltage application at which the rise time (τr) and the fall time (τd) become equal at 20 ° C.

  To this, the representative formula (I-1) obtained in Example 1 among the compounds represented by the general formula (I)

A liquid crystal composition (M-1) comprising 20% by weight of the above compound and 80% by weight of the host liquid crystal (M) was prepared. The physical property values of (M-1) were as follows.
TN-I: 128.6 ° C
Response time (τr = τd): 21.0 ms Refractive index anisotropy (Δn): 0.108
As described above, it can be seen that the response time is shortened by about 20% even though the TN-I has increased by about 12 °.
(Comparative Example 1) Formula (IIa-1) represented by formula (IIa) having a cyclohexylbiphenyl skeleton similarly to formula (I) but having both side chains of a linear alkyl group

The physical properties of the composition (Ma-1) comprising 20% by weight of the compound and 80% by weight of the host liquid crystal (M) were as follows.
(Ma-1)
TN-I: 125.5 ° C
Response time (τr = τd): 22.5 ms Refractive index anisotropy (Δn): 0.105
Therefore, although both the response time and the nematic phase upper limit temperature (TN-I) are improved for the host liquid crystal (M), when compared with the physical property value of (M-1), (TN-I) is It can be seen that the response has been delayed by about 7% despite being about 3 ° lower.
(Comparative Example 2) Formula (IIb-1) and Formula (IIb) represented by Formula (IIb) having a cyclohexylbiphenyl skeleton similarly to Formula (I) but having a structure in which an alkenyl group is directly connected to a cyclohexane ring -2)

Was used to prepare a composition. Composition (Mb-1) comprising 20% by weight of the compound of formula (IIb-1) and 80% by weight of the host liquid crystal (M), 20% by weight of the compound of formula (IIb-2) and 80% by weight of the host liquid crystal (M) The physical properties of the composition consisting of (Mb-2) were as follows.
(Mb-1)
TN-I: 122.5 ° C
Response time (τr = τd): 22.1 ms Refractive index anisotropy (Δn): 0.109
(Mb-2)
TN-I: 128.5 ° C
Response time (τr = τd): 21.8 ms Refractive index anisotropy (Δn): 0.110
Therefore, the response time is improved for the host liquid crystal (M) and the above-mentioned (Ma-1), but the response is slow compared with the physical property value of (M-1). I understand.

Therefore, the compound of (I-1) of the present invention has (IIa-1), (IIb-1) or (IIb) in obtaining a liquid crystal composition having low viscosity, excellent responsiveness and a wide nematic phase temperature range. It is clear that an effect superior to the compound of -2) is exhibited.
Reference Example 3 Preparation of liquid crystal composition (2)
General-purpose host liquid crystal (H) for STN display

Was prepared. This host liquid crystal (H) exhibits a nematic phase at 54.5 ° C. or lower. The response time and refractive index anisotropy (Δn) of this composition were as follows.
Response time (τr = τd): 39.2 ms Refractive index anisotropy (Δn): 0.092
A nematic liquid crystal composition (H-1) comprising 80% of the host liquid crystal (H) and 20% of the compound of the formula (I-1) was prepared. The characteristic value of (H-1) was as follows.
TN-I: 78.9 ° C
Response time (τr = τd): 41.9 ms Refractive index anisotropy (Δn): 0.115
Thus, although the TN-I has increased by about 25 °, the response time has only increased by about 7%. Therefore, it can be seen that the compound (I-1) is extremely effective for obtaining a nematic liquid crystal composition having a wide temperature range up to a high temperature range and a low viscosity.

Claims (2)

Formula (I)

(Wherein R represents an alkyl group having 1 to 12 carbon atoms, ring A represents a 1,4-phenylene group optionally substituted with fluorine, and ring B represents a 1,4-phenylene group substituted with fluorine. R 'represents an alkyl group having 1 to 5 carbon atoms, and the double bond is cis (Z) or trans (E). In the general formula (I), alkenyl biphenyl derivative according to claim 1, wherein the at representing the ring B is 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene group.