JPH03120239A - New ester compound, liquid crystal composition and optical switching element containing the same - Google Patents

Abstract

NEW MATERIAL:An ester compound expressed by formula I [R1 and R2 are 2-18C alkyl; X is formula IV (p and q are 0, 1 or 2; B is bivalent chain group selected from single bond, -COO- or -OOC-; X1 and X2 are 6-membered ring- containing group which may have a substituent group)]. EXAMPLE:4-(2-Methyloctanoyl)biphenyl 4-(2-methylbutyloxy)benzoate. USE:A component of liquid crystal compositions and optical switching elements, having different chiral groups at both molecular terminals, i.e., 2-methylalkanoyl group, with great dipole moment and contributing to development of spontaneous polarization as either thereof and 2-methylalkoxy group as the other and further a stable Sc* phase. PREPARATION:For example, a 2-methylalkanol, such as a compound expressed by formula II, and a benzoic acid derivative, such as a compound expressed by formula III (Y is H, Cl or CH3), are subjected to esterifying reaction to afford the compound expressed by formula I.

Description

[Detailed Description of the Invention] [Industrial Application Field J] The present invention can take a stable thermotropic liquid crystal state,
For example, a new ester compound that can be used as a liquid crystal material that is useful as a material for optoelectronics-related elements that use liquid crystals or electrochemical microsm, such as optical printer heads for displays such as LCD televisions, optical Fourier transform elements, and light valves. The present invention relates to a liquid crystal composition containing the present invention and an optical switching element.

[Prior Art] The emergence of ferroelectric liquid crystals, with 4-(4-n-decyloxybenzylideneamino)cinnamic acid-2-methylbutyl ester (DOBAMBC) synthesized by R0B and Meyer et al. in 1975 as a representative example. and N using it,
A.

A new display method proposed by C1ark et al. [Appl, P
hys.

μse by Lett, 36.899 (1980))
It has now become possible to create a liquid crystal cell that has c-order high-speed response and the property that the orientation does not change even when the electric field is turned off (memory property). For this reason, many ferroelectric liquid crystal materials have been synthesized and proposed to date. In order to obtain this ferroelectric liquid crystal, it is necessary to introduce an optically active group into the compound that becomes the liquid crystal. Conventionally, 2-methylbutanol and 2-octatool have been used as chiral sources for this optically active group. It was getting worse. Recently, ferroelectric liquid crystal compounds using amino acids or lactic acid as chiral sources have been proposed.

Among these, a compound expressed by the following formula using amino acids was proposed [Proceedings of the 12th International Liquid Crystal Conference Freiburg FE18 P, 294 (1988)], and a compound using lactic acid was proposed by the following formula: A compound represented by is proposed (14th Liquid Crystal Symposium Sendai Lecture Proceedings P, 52 (19
88)) C,H,,OOCH,C"HOCOC冨H-QC,H.

Maximum spontaneous polarization in Sc” phase is 500nC/cnt
It shows.

Furthermore, it has different chiral groups at both ends of the molecule,
With the aim of satisfying multiple conditions required as a chiral dopant, such as having a large induced spontaneous polarization (P,), having a large helical pitch induced in the NX phase, and exhibiting liquid crystallinity as much as possible, A compound of the following formula has been proposed [14th Liquid Crystal Symposium Sendai Lecture Proceedings P.
, I8 (198g)].

C1H1, O-◎-■-〇-〇〇-C”H-C”H-C
,H.

This means that the maximum spontaneous polarization in the Sc” phase is 400 nC.
/ad is shown.

This compound has low liquid crystallinity as a single substance, and the spontaneous polarization obtained by extrapolation is 200 nC/cn? That's about it.

[Problem to be solved by the invention] [1] The present invention was made in view of the above-mentioned current situation, and an object of the present invention is to exhibit a stable Sc” phase and exhibit even greater spontaneous polarization than the above-mentioned conventional compounds. An object of the present invention is to provide a novel compound having the same composition, a liquid crystal composition containing the same, and an optical switching element containing this compound as a constituent element.

[Means to solve the problem J The present invention relates to general formula (I) CH, CH.

[In the formula, R1 and R1 are the same or different alkyl groups having 2 to 18 carbon atoms, and X is represented by the following general formula (
II) -(X,)p-B-(X,)q-(II) (where p
, q represents 0, l or 2, B is a single bond, -COO-
G1-00 also represents a divalent chain group selected from G-,
xl, X represents an included member ring group which may have a substituent) and a new ester compound containing this ester compound. The present invention is an optical switching element containing a liquid crystal composition and at least one of the above compounds as a constituent element.

The compound represented by the above general formula (I) of the present invention has different chiral groups at both ends of the molecule. In other words, one is 2-, which has a large dipole moment and contributes to the expression of spontaneous polarization.
One is a methylalkanoyl group and the other is a 2-methylalkoxy group. Therefore, this compound exhibits large spontaneous polarization and is stable as a single substance and as a composition.
It has a phase.

2- which is a necessary raw material for synthesizing the compound of the present invention
Methyl alkanol is commercially available and can be easily obtained. The higher the optical purity of this 2-methylalkanol, the more a compound with large spontaneous polarization can be obtained.
Although it is desirable to use an optical purity of 0% ee or higher, there is no problem even if the optical purity is lower than this.

In addition, R1 and R in the above formula (1) are selected to have carbon numbers in the range of 2 to 18 from the viewpoint of ease of obtaining synthetic raw materials.

Next, the nuclear structure, that is, the structure of -X- in the above formula (I), is -◎-CoO-◎-◎--◎-〇CO-◎-
◎−１−◎−◎−Co○−◎～, −■−■−0CO−◎
Examples include -1-Confucianism-◎-0CO-■-1CH1 1◎-○CO-◎--◎-◎-.

The compound of the above general formula (1) has the following formula: HOmC-C"H-R,,HOC(<co+C-C"H-
R,,R,c'HcH,o-◎-◎-COOH1 or rich CH.

R, C"HCH, O-◎-◎-○H CH.

It can be synthesized by carrying out an esterification reaction with an intermediate of (Y represents 1, CI, or Cl-1).

The former intermediate can be synthesized using commercially available 2-methylalkanol as a raw material by the method described in International Publication No. 88107518, which was previously filed and published by the applicant.

On the other hand, a benzoic acid derivative, which is one of the latter intermediates, can be synthesized according to the following scheme.

any intermediate of CH.

In addition, for 4-(2-methylbutyloxy)benzoic acid in which 4 is =c, H6, Y=H among these intermediates,
Since it is commercially available, it can be easily obtained.

Further, the intermediates described in the above scheme, 4-hydroxybenzoic acid, 3-chloro-4-hydroxybenzoic acid, and 2-methylalkanol, are easily available as commercial products. On the other hand, 3-methyl-4-hydroxybenzoic acid is
It is synthesized from commercially available 2-methylanisole according to the following scheme.

Further, other intermediates can also be synthesized by using commercially available materials and by alkylation similar to the above.

Next, the effects of the present invention will be specifically explained with reference to Examples.

[Example] (Example 1) 4-2-methyloctanorubiphenyl 4-4-(2methyloctanoyl)-4'-hydroxybiphenyl 1
, 55g (5n+mol), commercially available 4-(-2methylbutyloxy)benzoic acid 1.04g (5mmol), methylene chloride 10+nQ, N,N'-dicyclohexylcarbodiimide 1.05g (5.1mmol), 061 g of dimethylaminopyridine was stirred at room temperature for 4 hours. Insoluble materials were filtered off, the filtrate was concentrated, and the resulting concentrate was recrystallized from 30mα ethanol to yield 1.15g (2
, 3 mmol) of a white solid with the following physical properties.
-Methyloctanoyl)biphenyl 4(2-methylbutyloxy)benzoic acid ester was obtained.

1, R, (KBr, cm −'); 1730,16
85NMR (CDCI, ppm); 8.16 (d
, 2l-1), 8.06 (d, 2H), 7.84 (d,
2H), 7.48 (d, 2H), 7.00 (d, 211
), 3.95 (d.

lH), 3.92 (d, IH), 3.48 (m, I
H), 2.13-0.80 (m, 26H) Toyo 1J11 The phase transition behavior of the above compound was measured by controlling the temperature on a hot stage and observing it using a crossed Nicol microscope. The temperature was raised and lowered at a rate of 2°C/min. During the cooling process, it changed from an isotropic liquid to a smectic A phase (Sa) at 100.4°C, changed to a xyl smectic C phase (Sc'') at 75.0°C, and further crystallized at 31.6°C. In this case, the crystals melted at 66.7°C and became a xylsmectic C phase (Sc''). In addition, the compound was injected into a cell with a thickness of 4 μm made of glass with transparent electrodes coated with Bolimide and subjected to rubbing treatment, and the magnitude of spontaneous polarization was measured using the triangular wave method.
It was a very large value of 5 nC/cIa and 540 nC/d at 35°C.

Next, as a comparative example, the phase transition temperature and spontaneous polarization are shown in Table 1 for comparison with a compound of the following formula whose structure is relatively similar to the compound of the present invention.

C9H,0-e-Coo-e-◎-C-C”H-C,H
,.

Table 1 Cry Sc” Sa Iso
ΔT=10℃ Maximum value part, 7・75.0・100
．． 4 ・205 540 (35,0℃) 141
．． 3(-71,7-141,0)-100203(46
,rc:)" Tac-T=lO℃ Thus, the comparative example changed from a crystal to an isotropic liquid at 141.3℃, and did not show liquid crystal when the temperature was raised.
s is also less than half that of Example 1.

The compound obtained in the present invention has a stable Sc” compared to the comparative example.
It has a phase and a large spontaneous polarization.

Example 1 Comparative Example A base liquid crystal was used in which a non-chiral phenylpyrimidine compound was mixed to form a cholesteric phase at 67 to 62°C, a smectic A phase at 62 to 47°C, and a smectic C phase at 47 to 7°C. The compound shown in Example 1 was added in a weight ratio of 50:6.
When mixed at 67.0-65.7°C, the cholesteric phase, 65.7-37.0°C, the smectic A phase,
A good ferroelectric liquid crystal composition having a xylsmectic C phase at 37.0 to -1.9°C was obtained.

When the compounds of the above comparative example were mixed under the same conditions, 68.
Smectic A phase at 8-64.9°C, 5.2--1.7
The xyl smectic C phase was observed at 100° C., and the stability of the xyl smectic C phase was significantly lower than that of the composition using Example 1.

The above liquid crystal composition using the compound of the present invention is injected into a cell with a thickness of 1.6 μm made of glass with a transparent electrode coated with polyimide and subjected to a rubbing treatment, and the liquid crystal composition is gradually changed from an isotropic liquid state. After lowering the temperature and obtaining a well-oriented xyl smectic C phase, an electric field was applied to the cell while observing it with a crossed Nicol polarizing microscope, and optical switching behavior was observed, and the response time at 25°C was 44μ.
It was s.

〔Effect of the invention〕

As explained above, the compound obtained according to the present invention can exhibit extremely large spontaneous polarization, and has excellent stability of the xylsmectic C phase both as a simple substance and as a liquid crystal composition.

The compound provided by the present invention, the liquid crystal composition containing the same, and the optical switching device have large spontaneous polarization, quick response, and are useful as display materials for optoelectronics.

Claims (3)

[Claims] (1) General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) [In the formula, R_1 and R_2 are the same or different alkyl groups having 2 to 18 carbon atoms, and X is the following General formula (II) -(X_1)p-B-(X_2)q-(II) (where,
p, q represent 0, 1 or 2, B is a single bond, -COO
- or -OOC- represents a divalent chain group,
_1 and X_2 are six-membered ring-containing groups that may have substituents)
An ester compound consisting of a six-membered ring-containing group represented by: (2) A liquid crystal composition containing an ester compound represented by the general formula (I) of claim (1). (3) An optical switching element comprising at least one compound represented by the general formula (I) of claim (1) as a constituent element.