JP2019151597A - Novel chiral dopant and liquid crystal composition - Google Patents

Abstract

To provide a cholesteric liquid crystal capable of changing a reflected color even if a low voltage is applied.SOLUTION: The invention provides a compound represented by formula (I) in the figure. [Xand Xeach represent an oxygen atom or the like; Y represents a single bond, a substituted/unsubstituted C1-10 alkylene group, a nitrogen atom, or P(=O)-O; T represents a linking group; Fc represents ferrocene or a derivative thereof; n, s and t each represent an integer from 0 to 2, provided that one or two thereof represent 1 or 2; Rand Reach represent a C1-18 alkyl group; and p and q each represent an integer from 0 to 6.]SELECTED DRAWING: Figure 1

Description

  The present invention relates to a novel chiral dopant compound, more specifically. The present invention relates to a redox-responsive chiral dopant for the reflection color modulation of cholesteric liquid crystals. The present invention also relates to a liquid crystal composition containing the chiral dopant and a reflective display using the liquid crystal composition.

  A cholesteric liquid crystal has a feature that it forms a molecular arrangement of a spiral structure and selectively reflects circularly polarized light having a wavelength corresponding to its period (pitch). A cholesteric liquid crystal is usually prepared by adding an optically active guest molecule (chiral dopant or chiral agent) to a nematic liquid crystal that is a liquid crystal having a low structural order to impart optical rotation.

The central wavelength (λ) of the reflected light of the cholesteric liquid crystal has the following relationship with the average refractive index (n) and pitch (P) of the liquid crystal.

  That is, when the pitch of the spiral structure is increased, light having a long wavelength is reflected, and when the pitch is decreased, light having a short wavelength is reflected. If λ is a wavelength in the visible region, the liquid crystal exhibits a beautiful reflected color.

Moreover, when adding a chiral dopant to a liquid crystal, the said (1) Formula can be represented by the following formula | equation. In Formula (2), c is a dopant concentration, and β is a helical twisting power (HTP) (μm ⁻¹ ).

  From equation (2), the higher the concentration of the chiral dopant, the shorter the reflected color, and the higher the HTP, the shorter the wavelength.

  A display using a cholesteric liquid crystal having such characteristics (reflective display) has an advantage that power consumption is small because a backlight is not necessary, whereas a conventional liquid crystal display requires a backlight. . However, the conventional reflective display using cholesteric liquid crystal can only show two states of transmitting or reflecting light and cannot control the reflected color.

  Therefore, if the molecular arrangement of the helical structure can be controlled by electrical stimulation and the reflected color of the cholesteric liquid crystal can be modulated, it can be used as a new type of reflective display in combination with the existing display technology. However, to change the reflection color of the cholesteric liquid crystal, a large voltage of several tens of volts has been required so far (Non-Patent Documents 1 and 2).

On the other hand, in recent years, attempts have been made to control the molecular arrangement of liquid crystals using a stimulus-responsive chiral additive instead of the method of controlling the molecular arrangement of cholesteric liquid crystals by electrical stimulation.
Up to now, for the purpose of modulating the reflection color of cholesteric liquid crystal, a method using a photoresponsive dopant (Non-Patent Document 3), a method using a gas-responsive dopant (Non-Patent Document 4), and controlling the concentration of the dopant by temperature are used. The method (Nonpatent literature 5) etc. to do has been studied. However, electrical stimulation responsive dopants have not yet been developed.

G. P. Crawford et al., Appl. Opt. 2004, 43, 5006-5015. A. Y.-G. Fuh et al., Appl. Phys. Lett. 2006, 88, 061122. Q. Li et al., J. Am. Chem. Soc. 2012, 134, 9573-9576 R. P. Sijbesma et al., J. Am. Chem. Soc., 2010, 132, 2961-2967. S.-T.Wu et al. ,, Opt. Express, 2006, 14, 1236-1242

An object of the present invention is to provide a novel chiral dopant having an ability to induce a helical structure in order to develop a cholesteric liquid crystal.
Another object of the present invention is to provide a novel cholesteric liquid crystal that can change the reflection color even when a low voltage is applied by using a novel chiral dopant.

The inventors of the present invention diligently studied to solve the above-mentioned problems, and made an original discovery that the ability of the dopant to form a liquid crystal helix changes when the chiral dopant is imparted with ionicity. That is, it was found that a chiral dopant that responds to electrical stimulation can be obtained by imparting to the chiral dopant a site that reversibly switches between ionic and nonionic properties by electrical stimulation.
Here, the present inventors have focused on introducing a chiral dopant into a site having redox reaction activity. Such a site has the property of causing an oxidation-reduction reaction at a low voltage and switching between ionic and nonionic properties. The present inventors have found that a new cholesteric liquid crystal capable of changing the reflection color at a low voltage can be developed by using the chiral dopant thus developed, and the present invention has been completed.

（式中、
Ｘ^１及びＸ^２は、各々独立に、酸素、ＣＲ^３Ｒ^４、ＮＲ^３からなる群から選択され、
ここで、Ｒ^３及びＲ^４は、各々独立に、水素、炭素原子１〜１８のアルキル基であり；
Ｙは、単結合、炭素原子１〜１０の置換又は無置換のアルキレン基、窒素、Ｐ（＝Ｏ）−Ｏからなる群から選択され：
Ｔは、連結基であり；
Ｆｃは、フェロセン又はフェロセン誘導体であり：
ｎは０〜２の整数であり、ｓは０〜２の整数であり、ｔは０〜２の整数であり、ｎ、ｓ及びｔのいずれか１つもしくは２つが１もしくは２であり：
Ｒ^１及びＲ^２は、各々独立に、炭素原子１〜１８のアルキル基であり；
ｐは０〜６の整数であり、ｑは０〜６の整数である。）
［２］前記連結基が、カルボニル基、エステル基（−ＣＯＯ−、−ＯＣＯ−）、アルキルエステル基（−Ｒ−ＣＯＯ−、−Ｒ−ＯＣＯ−）、アミド基、アルキルアミド基、カルボニルアミノ基、エーテル基又はアルキルエーテル基から選択される、［１］に記載の化合物。
［３］Ｙの置換又は無置換のアルキレン基が、−（ＣＲ^５Ｒ^６）_ｍ−（Ｃ^＊１Ｒ^５）−（ＣＲ^５Ｒ^６）_ｌ−で表される（ここで、Ｒ^５及びＲ^６は、各出現において独立に、水素、炭素原子１〜１８のアルキル基であり、ｍは、０〜２０の整数であり、ｌは、０〜２０の整数であり、＊１は、一般式（Ｉ）中の−（Ｔ−Ｆｃ）_ｎ（但し、ｎは１である）と結合する結合位置を示す）、［１］又は［２］に記載の化合物。
［４］Ｘ^１及びＸ^２が、酸素である、［１］〜［３］のいずれか１項に記載の化合物。
［５］Ｙが、−ＣＨ_２−Ｃ^＊１Ｈ−ＣＨ_２−である、［３］又は［４］に記載の化合物。
［６］Ｆｃが、以下の式（ＩＩ）で表される、［１］〜［５］のいずれか１項に記載の化合物。

（式中、
Ｒ^７、Ｒ^８、Ｒ^９、Ｒ^１０、Ｒ^１１、Ｒ^１２、Ｒ^１３、Ｒ^１４及びＲ^１５は、各々独立に、水素原子又は置換基を表し、＊２は、一般式（Ｉ）中のＴと結合する結合位置を示す。）
［７］［１］〜［６］のいずれか１項に記載の化合物を含む液晶組成物。
［８］選択反射を示し、電場による酸化還元反応によって選択反射波長が変化する液晶組成物であって、以下の式（Ｉ）で表されるキラルドーパントを含有する液晶組成物。

（式中、
Ｘ^１及びＸ^２は、各々独立に、酸素、ＣＲ^３Ｒ^４、ＮＲ^３からなる群から選択され、
ここで、Ｒ^３及びＲ^４は、各々独立に、水素、炭素原子１〜１８のアルキル基であり；
Ｙは、単結合、炭素原子１〜１０の置換又は無置換のアルキレン基、窒素、Ｐ（＝Ｏ）−Ｏからなる群から選択され：
Ｔは、連結基であり；
Ｆｃは、フェロセン又はフェロセン誘導体であり：
ｎは０〜２の整数であり、ｓは０〜２の整数であり、ｔは０〜２の整数であり、ｎ、ｓ及びｔのいずれか１つもしくは２つが１もしくは２であり：
Ｒ^１及びＲ^２は、各々独立に、炭素原子１〜１８のアルキル基であり；
ｐは１〜６の整数であり、ｑは１〜６の整数である。）
［９］少なくとも１種以上の前記キラルドーパント、支持電解質、及びホスト液晶を含有する［８］に記載の液晶組成物。
［１０］少なくとも一方が透明電極である一対の電極と、
前記電極間に、［１］〜［９］のいずれか１項に記載の液晶組成物を含有する液晶層と、
を有する液晶素子。
［１１］［１０］に記載の液晶素子を備える反射型液晶ディスプレイ。
［１２］［１］〜［６］のいずれか１項に記載の化合物を用いた酸化剤センサー。
を、提供することである。 That is, the present invention
[1] A compound represented by the following formula (I).

(Where
X ¹ and X ² are each independently selected from the group consisting of oxygen, CR ³ R ⁴ , NR ³ ;
Where R ³ and R ⁴ are each independently hydrogen, an alkyl group of 1 to 18 carbon atoms;
Y is selected from the group consisting of a single bond, a substituted or unsubstituted alkylene group of 1 to 10 carbon atoms, nitrogen, P (= O) -O:
T is a linking group;
Fc is ferrocene or a ferrocene derivative:
n is an integer from 0 to 2, s is an integer from 0 to 2, t is an integer from 0 to 2, and any one or two of n, s, and t is 1 or 2:
R ¹ and R ² are each independently an alkyl group of 1 to 18 carbon atoms;
p is an integer of 0-6, and q is an integer of 0-6. )
[2] The linking group is a carbonyl group, an ester group (—COO—, —OCO—), an alkyl ester group (—R—COO—, —R—OCO—), an amide group, an alkylamide group, or a carbonylamino group. The compound according to [1], selected from an ether group or an alkyl ether group.
[3] A substituted or unsubstituted alkylene group represented by Y is represented by — (CR ⁵ R ⁶ ) _m — (C ^{* 1} R ⁵ ) — (CR ⁵ R ⁶ ) ₁ — (wherein R ⁵ and R ⁶ is independently at each occurrence hydrogen, an alkyl group having 1 to 18 carbon atoms, m is an integer of 0 to 20, l is an integer of 0 to 20, and * 1 is The compound according to [1] or [2], which represents a binding position that binds to-(T-Fc) _n (wherein n is 1) in formula (I).
[4] The compound according to any one of [1] to [3], wherein X ¹ and X ² are oxygen.
[5] The compound according to [3] or [4], wherein Y is —CH ₂ —C ^{* 1} H—CH ₂ —.
[6] The compound according to any one of [1] to [5], wherein Fc is represented by the following formula (II).

(Where
R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ^14, and R ¹⁵ each independently represent a hydrogen atom or a substituent, and * 2 in the general formula (I) The binding position for binding to T is shown. )
[7] A liquid crystal composition comprising the compound according to any one of [1] to [6].
[8] A liquid crystal composition that exhibits selective reflection and has a selective reflection wavelength that changes due to an oxidation-reduction reaction by an electric field, comprising a chiral dopant represented by the following formula (I):

(Where
X ¹ and X ² are each independently selected from the group consisting of oxygen, CR ³ R ⁴ , NR ³ ;
Where R ³ and R ⁴ are each independently hydrogen, an alkyl group of 1 to 18 carbon atoms;
Y is selected from the group consisting of a single bond, a substituted or unsubstituted alkylene group of 1 to 10 carbon atoms, nitrogen, P (= O) -O:
T is a linking group;
Fc is ferrocene or a ferrocene derivative:
n is an integer from 0 to 2, s is an integer from 0 to 2, t is an integer from 0 to 2, and any one or two of n, s, and t is 1 or 2:
R ¹ and R ² are each independently an alkyl group of 1 to 18 carbon atoms;
p is an integer of 1 to 6, and q is an integer of 1 to 6. )
[9] The liquid crystal composition according to [8], comprising at least one kind of chiral dopant, a supporting electrolyte, and a host liquid crystal.
[10] a pair of electrodes, at least one of which is a transparent electrode;
Between the electrodes, a liquid crystal layer containing the liquid crystal composition according to any one of [1] to [9];
A liquid crystal element having
[11] A reflective liquid crystal display comprising the liquid crystal element according to [10].
[12] An oxidant sensor using the compound according to any one of [1] to [6].
Is to provide.

According to the present invention, it is possible to provide a novel chiral dopant having an ability to induce a helical structure in order to develop a cholesteric liquid crystal.
Further, by using the chiral dopant of the present invention, it is possible to provide a new cholesteric liquid crystal capable of changing the reflection color at a low voltage.

It is a transmission spectrum of a cholesteric liquid crystal sample. It is a transmission spectrum of a cholesteric liquid crystal sample. 6 is a diagram illustrating a liquid crystal element including a cholesteric liquid crystal phase manufactured in Example 2. FIG. 4 is a transmission spectrum of a liquid crystal element including a cholesteric liquid crystal phase produced in Example 2. 4 is a transmission spectrum of a liquid crystal element including a cholesteric liquid crystal phase produced in Example 2.

1. One embodiment of the chiral dopant present invention is a compound represented by the following formula (I).

In formula (I), X ¹ and X ² are each independently selected from the group consisting of oxygen, CR ³ R ⁴ , NR ³ .
Here, R ³ and R ⁴ are each independently hydrogen or an alkyl group having 1 to 18 carbon atoms.

In one preferred aspect of the invention, both X ¹ and X ² are oxygen.

In another preferred aspect of the invention, both X ¹ and X ² are CH ₂ .

In the formula (I), Y is selected from the group consisting of a single bond, a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, nitrogen, and P (═O) —O. However, when both X ¹ and X ² are oxygen, Y is not a single bond.

A substituted or unsubstituted alkylene group of Y is _{^{preferably, - (CR 5 R 6)}} m - (C * 1 R 5) - (CR 5 R 6) l - represented by.
Here, R ⁵ and R ⁶ are each independently hydrogen or an alkyl group having 1 to 18 carbon atoms.
Moreover, m is an integer of 0-20, l is an integer of 0-20.
* 1 indicates a binding position that binds to-(T-Fc) _n (where n is 1) in general formula (I).

Another preferred example of substituted or unsubstituted alkylene group for _{^{Y, - (CR 5 R 6)}} m - (C * 1 * 2) - (CR 5 R 6) l - represented by.
Here, R ⁵ and R ⁶ are each independently hydrogen, an alkyl group having 1 to 18 carbon atoms, m is an integer of 0 to 20, and l is an integer of 0 to 20. .
* 1 and * 2 represent binding positions for binding to-(T-Fc) _n (when n is 2) in the general formula (I).

One preferred example of a substituted or unsubstituted alkylene group for Y is —CH ₂ —C ^{* 1} H—CH ₂ —.

One preferred aspect of the present invention is a compound wherein in formula (I) both X ¹ and X ² are oxygen and Y is —CH ₂ —C ^{* 1} H—CH ₂ —. This is because this compound has a high helix-inducing power, can arrange ferrocene near the binaphthyl skeleton, and is easy to synthesize.

In formula (I), T represents a linking group.
Examples of the linking group include a carbonyl group, an ester group (—COO—, —OCO—), an alkyl ester group (—R—COO—, —R—OCO—), an amide group, an alkylamide group, a carbonylamino group, and an ether group. Or it is selected from alkyl ether groups.

In formula (I), Fc is ferrocene or a ferrocene derivative.
In the present invention, it is important to introduce ferrocene or a ferrocene derivative into the skeleton structure of the chiral dopant of the formula (I). That is, a chiral dopant that responds to electrical stimulation can be obtained by imparting ferrocene or a ferrocene derivative to the chiral dopant as a site that reversibly switches between ionic and nonionic properties by electrical stimulation. The ferrocene or ferrocene derivative site has the property of causing an oxidation-reduction reaction by low voltage to switch between ionic and nonionic properties. Therefore, by adding the compound of formula (I) to the liquid crystal molecule, the reflection color can be reduced at low voltage. It is possible to obtain a cholesteric liquid crystal capable of changing. Organic compounds generally become unstable when oxidized or reduced, and will decompose and polymerize even when placed in the air, but ferrocene does not have this, and after oxidation (ionic) However, since it can exist stably, it is considered effective for stabilization of the device.

Fc of formula (I) can be represented by the following formula (II).

In the formula (II), R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁵ each independently represent a hydrogen atom or a substituent. Moreover, * 2 shows the coupling | bonding position couple | bonded with T in general formula (I).

R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ^{15 have} a substituent of 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably carbon atoms. An alkyl group having 1 to 8 carbon atoms, a halogen atom (for example, chlorine, bromine, iodine, fluorine), 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably an alkoxy group having 1 to 8 carbon atoms (for example, methoxy, Ethoxy, 2-methoxyethoxy, 2-phenylethoxy, etc.).

  In formula (I), n is an integer of 0-2, s is an integer of 0-2, and t is an integer of 0-2. However, any one or two of n, s, and t is 1 or 2.

In formula (I), R ¹ and R ² each independently represent a monovalent substituent. The monovalent substituent is, for example, an alkyl group having 1 to 18 carbon atoms.

In formula (I), p is an integer of 0-6, and q is an integer of 0-6. When p and q are 0, the binaphthalene of the formula (I) has a structure having no substituent.
Further, when p and q are 2 or more, each R ¹ and each R ² may be the same or different.

When R ¹ and R ² are present, it is preferable from the viewpoint of steric hindrance that each of R ¹ and R ² is introduced at the 3-position and / or the 6-position of each naphthalene ring of formula (I).

Moreover, one preferable aspect of the present invention is a compound represented by the following formula (1).

In the formula (1), T, Fc, R ¹ , R ² , n, s, t, p, q are as defined in the formula (I).

In the formula (I), if Y is a single bond, general formula (I) in - _{(T-Fc) n} is bonded directly to either the ^{X 1} or ^{X 2.}

The present invention also includes compounds of the formula (I) in which both X ¹ and X ² are CH ₂ and Y is a single bond.

Examples of such a compound include compounds represented by the following formula (2a) or (2b).

In the formulas (2a) and (2b), T, Fc, R ¹ , R ² , n, s, t, p, and q are as defined in the formula (I).

2. Liquid Crystal Composition Another embodiment of the present invention is a liquid crystal composition containing a chiral dopant represented by the following formula (I) (hereinafter also referred to as “liquid crystal composition of the present invention”).

In the formula (I), X ¹ , X ² , Y, T, Fc, n, s, t, R ¹ , R ² , p, q are as described in detail above.

  Since the compound represented by formula (I) (chiral dopant) has the ability to induce a helical structure of liquid crystal, the liquid crystal composition of the present invention can exhibit cholesteric liquid crystal.

  The liquid crystal composition of the present invention exhibits selective reflection, and the selective reflection wavelength can be changed by an oxidation-reduction reaction by an electric field.

  The liquid crystal composition of the present invention preferably contains at least one chiral dopant represented by the formula (I), a supporting electrolyte, and a host liquid crystal.

  The concentration of the chiral dopant of formula (I) in the liquid crystal composition is 1 to 10 mol%, preferably 1 to 5 mol%.

Examples of the liquid crystal compound include a liquid crystal compound exhibiting a nematic phase or a smectic phase, and specific examples thereof include azomethine compounds, cyanobiphenyl compounds, cyanophenyl esters, fluorine-substituted phenyl esters, cyclohexanecarboxylic acid phenyl esters, fluorine Substituted cyclohexane carboxylic acid phenyl ester, cyanophenyl cyclohexane, fluorine substituted phenyl cyclohexane, cyano substituted phenyl pyrimidine, fluorine substituted phenyl pyrimidine, alkoxy substituted phenyl pyrimidine, fluorine substituted alkoxy substituted phenyl pyrimidine, phenyl dioxane, tolan compounds, fluorine substituted tolan compounds And alkenylcyclohexylbenzonitrile.
For details, refer to Japan Society for the Promotion of Science 142nd Committee, Liquid Crystal Device Handbook, Nikkan Kogyo Shimbun, 1989, pages 154-192 and pages 715-722.

支持電解質は、ホスト液晶に対する溶解性が高いものが好ましい。
支持電解質は、単独で用いてもよいし、２種以上を併用してもよい。 As the supporting electrolyte used in the liquid crystal composition of the present invention, conductivity is imparted to the liquid crystal composition. There is no particular limitation as long as this is possible, and a supporting electrolyte (nBu ₄ NPF ₆ , nBu ₄ NBF ₄ , nBu ₄ NClO ₄ ) or an ionic liquid that is generally used in electrochemistry can be used. As the ionic liquid, for example, one having the following structure can be used.

The supporting electrolyte preferably has high solubility in the host liquid crystal.
A supporting electrolyte may be used independently and may use 2 or more types together.

  The content of the supporting electrolyte is 1 to 30 mol%, preferably 1 to 15 mol%.

Moreover, the liquid crystal composition of the present invention can contain an oxidizing agent. The oxidizing agent reacts with ferrocene or a ferrocene derivative introduced into the skeleton structure of the chiral dopant to realize a redox reaction. Examples of such an oxidizing agent include NO ⁺ BF ₄ ^{− and the} like.

  When adding an oxidizing agent, the content is 1-10 mol%, Preferably it is 1-5 mol%.

The liquid crystal composition of the present invention has various liquid crystal and non-liquid crystal compounds for the purpose of changing the physical properties of the host liquid crystal (for example, the temperature range of the liquid crystal phase) to a desired range and promoting the oxidation-reduction reaction. Can be added. Moreover, you may contain compounds, such as a ultraviolet absorber and antioxidant.
Moreover, the liquid crystal composition of the present invention may contain a chiral dopant other than the chiral dopant of the formula (I).

3. Liquid Crystal Element Another embodiment of the present invention is a liquid crystal element having a pair of electrodes, at least one of which is a transparent electrode, and a liquid crystal layer containing the liquid crystal composition of the present invention between the electrodes (hereinafter, “ Also referred to as “liquid crystal element of the present invention”).

  The liquid crystal element of the present invention has a pair of electrodes, at least one of which is a transparent electrode, and a liquid crystal layer containing the liquid crystal composition of the present invention between the electrodes. Further, a black plate, an antireflection film, a brightness enhancement film, and the like may be provided.

The liquid crystal element of the present invention can be constituted by being sandwiched between a pair of electrode substrates. As the electrode substrate used in the liquid crystal element of the present invention, a glass or plastic substrate is usually used.
Examples of the plastic substrate used in the present invention include acrylic resin, polycarbonate resin, and epoxy resin. For example, triacetyl cellulose, polyethylene terephthalate, polyethylene naphthalate, syndiotactic polystyrene, polyphenylene sulfide, polycarbonate, polyarylate, polysulfone. , Polyester sulfone, polyetherimide, cyclic polyolefin, polyimide and the like.

The thickness of the plastic substrate is not particularly limited, but is preferably 30 μm to 700 μm, more preferably 40 μm to 200 μm, and still more preferably 50 μm to 150 μm.
Further, in any case, the haze is preferably 3% or less, more preferably 2% or less, still more preferably 1% or less, and the total light transmittance is preferably 70% or more, more preferably 80% or more, and further preferably 90%. That's it.

  The plastic substrate may be either light transmissive or non-light transmissive. When a non-light-transmissive support is used as the support, a black support that does not have light reflectivity on the non-display surface side can be used. Examples of the black support include a plastic substrate to which an inorganic pigment such as carbon black is added.

An electrode layer is formed on the surface of the pair of substrates, and at least the electrode layer is a transparent electrode. As the electrode layer, indium oxide, indium tin oxide (ITO), tin oxide, PEDOT-PSS, silver nanorod, carbon nanotube, or the like is used.
The transparent electrode 10 can be formed by a sputtering method, a sol-gel method, or a printing method.

  In addition, among the pair of substrates, the electrode layer used for the substrate paired with the substrate on which the transparent electrode layer is formed may be a transparent electrode layer or a non-transparent electrode layer. In the case of an electrode layer, a GC electrode or the like can be used.

  In the liquid crystal element of the present invention, a conductive polymer layer is preferably provided on the electrode in order to perform a redox reaction with the compound of formula (I) in the liquid crystal layer. As such a conductive polymer, a thiophene-based conductive polymer (PEDOT (for example, trade name: Aedotron (trademark) C3-NM (sales company: Aldrich), etc.)) and the like are preferable.

  In the liquid crystal element of the present invention, the electrode surface may or may not be rubbed for the purpose of aligning the liquid crystal.

In the liquid crystal element of the present invention, a gap (cell gap) is provided between a pair of substrates via a spacer or the like, and the liquid crystal composition can be injected into the space.
Moreover, the liquid crystal composition of the present invention can be disposed in the space between the substrates by coating or printing on the substrates.

  The liquid crystal element of the present invention includes other members such as a barrier film, an ultraviolet absorbing layer, an antireflection layer, a hard coat layer, a stain prevention layer, an organic interlayer insulating film, a metal reflector, a retardation plate, an alignment film, and the like. You can also. These may be used alone or in combination of two or more.

  The liquid crystal element of the present invention can be driven by a simple matrix driving method or an active matrix driving method using a thin film transistor (TFT).

  In the liquid crystal element of the present invention, the absolute value of the drive voltage is preferably 0.1 V to 20 V, more preferably 0.3 V to 15 V, and still more preferably 0.5 V to 1.0 V.

  Next, a toning method in the liquid crystal element of the present invention will be described.

  A liquid crystal composition containing a chiral dopant of formula (I) and a supporting electrolyte is injected into the counter electrode cell. The electrode cell into which the liquid crystal composition has been injected exhibits selective reflection. Next, toning is performed by applying a DC voltage equal to or higher than the redox potential of the chiral dopant to the electrode cell. The change width of the selective reflection length can be controlled by changing the application time (adjusting the reaction amount of the chiral dopant).

In order to restore the selective reflection wavelength, a reverse voltage is applied. For example, when a selective reflection wavelength is changed by applying a voltage of 1.5 V, a selective reflection wavelength is restored by applying a voltage of -1.5 V.
In this way, the selective reflection wavelength of the liquid crystal composition can be changed.

  Another embodiment of the present invention is a reflective liquid crystal display comprising the liquid crystal element of the present invention.

  Another embodiment of the present invention is an oxidant sensor using a compound of formula (I).

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

[Synthesis Example 1]

(Synthesis of Compound 2)
To a solution of (R)-(+)-1,1′-bi (2-naphthol) (manufactured by Tokyo Chemical Industry) (2.00 g) in N, N-dimethylformamide solution (60 mL) under ice cooling, 60% oil hydrogen Sodium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) (0.7 g) was added, and the mixture was stirred at room temperature for 1 hour under an argon atmosphere. Then, 3-chloro-2-chloromethyl-1-propene (0.87 g) was added dropwise, Stir at 60 ° C. for 3 hours. The reaction solution was poured into ethyl acetate / saturated aqueous ammonium chloride solution, and the organic layer was washed with saturated aqueous sodium chloride solution, dried over sodium sulfate, and concentrated under reduced pressure. The concentrated residue was purified by silica gel column chromatography (developing solvent: methylene chloride / hexane = 1/2) to obtain Compound 2 (1.85 g).

(Synthesis of Compound 3)
To a tetrahydrofuran solution (10 mL) of compound 2 (1.02 g), 0.9 M tetrahydrofuran-borane / tetrahydrofuran solution (manufactured by Wako Pure Chemical Industries, Ltd.) (5.4 mL) was added dropwise under ice cooling, followed by stirring for 1 hour. A 3.0 M aqueous sodium hydroxide solution (1.2 mL) was added dropwise to the reaction solution and stirred for 30 minutes, and then 30% aqueous hydrogen peroxide (1.2 mL) was added dropwise and stirred at room temperature for 1 hour. Potassium carbonate (600 mg) was added to the reaction solution, stirred for 10 minutes, poured into methylene chloride / water, the organic layer was washed with saturated aqueous sodium chloride solution, dried over sodium sulfate, and concentrated under reduced pressure. . The concentrated residue was purified by silica gel column chromatography (developing solvent: ethyl acetate / hexane = 1/1) to obtain Compound 3 (0.36 g).

(Synthesis of Compound ^Fc D of the ^Present Invention)
Triethylamine (102 mg) and oxalyl chloride (767 mg) were added to a methylene chloride solution (3.6 mL) of ferrocenecarboxylic acid (manufactured by Tokyo Chemical Industry) (237 mg) in an argon atmosphere, and the mixture was stirred at room temperature for 5 hours. After the reaction solution was concentrated under reduced pressure, Compound 3 (161 mg), 4-dimethylaminopyridine (26 mg), triethylamine (305 mg) and tetrahydrofuran (8.6 mL) were added, and then heated under reflux in an argon atmosphere under heating. Stir for hours. The reaction solution was poured into methylene chloride / water, and the organic layer was washed with a saturated aqueous sodium chloride solution, dried over sodium sulfate, and concentrated under reduced pressure. The concentrated residue was purified by silica gel column chromatography (developing solvent: ethyl acetate / hexane = 1/5), and the resulting crude product was purified by size exclusion chromatography and then washed with pentane to give compound ^Fc D ( 157 mg) was obtained.

The compound of the present invention ( ^Fc D) was identified by NMR and High Resolution MASS spectrum. The appearance was a yellow powder.
¹ H NMR (CDCl ₃ )
δ: 7.99 (2H, dd), 7.90 (2H, d), 7.59 (1H, d), 7.44 (1H, d), 7.36-7.40 (2H, m) 7.2-3.29 (4H, m), 4.77 (2H, d), 4.74 (1H, d), 4.62 (1H, d), 4.41 (2H, t), 4.30 (1H, dd), 4.16-4.30 (5H, m), 4.07 (1H, dd), 2.60-2.67 (1H, m).

[Example 1]
Using the compound ^Fc D of the present invention, the transmission spectrum was measured as follows.
1. Methylene chloride solution of a 4-cyano-4'-pentyloxy-biphenyl host liquid crystal, the compound ^Fc D respectively added 2.2～4.0Mol%, to prepare a cholesteric liquid crystal sample was concentrated under reduced pressure. A cholesteric liquid crystal sample was sealed in a glass cell having a cell thickness of 5 μm and a surface rubbed with a nylon cloth, and a transmission spectrum was measured at 40 ° C. at which a cholesteric liquid crystal phase was developed. The results are shown in FIG.
2. To the methylene chloride solution of 4-cyano-4'-pentyloxybiphenyl, which is the host liquid crystal, 2.2 to 4.0 mol% of FcD is added, and 1 equivalent of nitrosonium tetrafluoroborate is added to FcD. And a cholesteric liquid crystal sample concentrated under reduced pressure was prepared. A cholesteric liquid crystal sample was sealed in a glass cell having a cell thickness of 5 μm and a surface rubbed with a nylon cloth, and a transmission spectrum was measured at 40 ° C. at which a cholesteric liquid crystal phase was developed. The results are shown in FIG.

[Example 2]
1. To a methylene chloride solution of 4-cyano-4′-pentyloxybiphenyl as a host liquid crystal, 3.1 mol% of compound ^Fc D and 3.0 mol% of 1-ethyl-3-methylimidazolium triflate were added respectively, and the pressure was reduced. A concentrated cholesteric liquid crystal sample was prepared. A cholesteric liquid crystal sample was enclosed in a cell made of patterned ITO glass having a cell thickness of 5 μm and a surface rubbed with a nylon cloth, and a glass with ITO spin coated with PEDOT to produce the liquid crystal element shown in FIG. Subsequently, the transmission spectrum was measured at 40 ° C. at which a cholesteric liquid crystal phase was developed.
In the measurement of the transmission spectrum, a DC voltage of 1.5 V was applied to the cholesteric liquid crystal sample-encapsulated cell of the liquid crystal element shown in FIG. 3, and the transmission spectrum was measured. It was. The results are shown in FIG.
2. The above 1. except that the concentration of the compound ^Fc D in the cholesteric liquid crystal sample was changed to 2.6 mol%. In the same manner as above, a liquid crystal element was produced. Next, a direct current voltage of 1.5 V was applied to the cell in which the cholesteric liquid crystal sample was sealed, and the transmission spectrum was measured. Then, the direct current voltage application was stopped and the transmission spectrum was measured. The results are shown in FIG.

Claims (12)

The compound represented by the following formula (I).

(Where
X ¹ and X ² are each independently selected from the group consisting of oxygen, CR ³ R ⁴ , NR ³ ;
Where R ³ and R ⁴ are each independently hydrogen, an alkyl group of 1 to 18 carbon atoms;
Y is selected from the group consisting of a single bond, a substituted or unsubstituted alkylene group of 1 to 10 carbon atoms, nitrogen, P (= O) -O:
T is a linking group;
Fc is ferrocene or a ferrocene derivative:
n is an integer from 0 to 2, s is an integer from 0 to 2, t is an integer from 0 to 2, and any one or two of n, s, and t is 1 or 2:
R ¹ and R ² are each independently an alkyl group of 1 to 18 carbon atoms;
p is an integer of 0-6, and q is an integer of 0-6. )   The linking group is a carbonyl group, an ester group (—COO—, —OCO—), an alkyl ester group (—R—COO—, —R—OCO—), an amide group, an alkylamide group, a carbonylamino group, an ether group. Or a compound according to claim 1 selected from alkyl ether groups. A substituted or unsubstituted alkylene group for Y _{^{is, - (CR 5 R 6)}} m - (C * 1 R 5) - (CR 5 R 6) l - represented by (wherein in, ^{R 5} and ^{R 6} , Independently at each occurrence, hydrogen, an alkyl group of 1 to 18 carbon atoms, m is an integer of 0 to 20, l is an integer of 0 to 20, and * 1 is represented by the general formula (I )-(T-Fc) _n (wherein n is 1)), the compound according to claim 1 or 2. The compound according to any one of claims 1 to 3, wherein X ¹ and X ² are oxygen. Y ^{_{is, -CH 2 -C * 1 H-}} CH 2 - A compound according to claim 3 or 4. The compound according to any one of claims 1 to 5, wherein Fc is represented by the following formula (II).

(Where
R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ^14, and R ¹⁵ each independently represent a hydrogen atom or a substituent, and * 2 in the general formula (I) The binding position for binding to T is shown. )   The liquid crystal composition containing the compound of any one of Claims 1-6. A liquid crystal composition that exhibits selective reflection and has a selective reflection wavelength that changes by an oxidation-reduction reaction by an electric field, the liquid crystal composition containing a chiral dopant represented by the following formula (I):

(Where
X ¹ and X ² are each independently selected from the group consisting of oxygen, CR ³ R ⁴ , NR ³ ;
Where R ³ and R ⁴ are each independently hydrogen, an alkyl group of 1 to 18 carbon atoms;
Y is selected from the group consisting of a single bond, a substituted or unsubstituted alkylene group of 1 to 10 carbon atoms, nitrogen, P (= O) -O:
T is a linking group;
Fc is ferrocene or a ferrocene derivative:
n is an integer from 0 to 2, s is an integer from 0 to 2, t is an integer from 0 to 2, and any one or two of n, s, and t is 1 or 2:
R ¹ and R ² are each independently an alkyl group of 1 to 18 carbon atoms;
p is an integer of 1 to 6, and q is an integer of 1 to 6. )   The liquid crystal composition according to claim 8, comprising at least one kind of the chiral dopant, a supporting electrolyte, and a host liquid crystal. A pair of electrodes, at least one of which is a transparent electrode;
A liquid crystal layer containing the liquid crystal composition according to any one of claims 1 to 9, between the electrodes,
A liquid crystal element having   A reflective liquid crystal display comprising the liquid crystal element according to claim 10.   The oxidizing agent sensor using the compound of any one of Claims 1-6.

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