JP2022185494A - Polymerizable liquid crystal composition and polarizer - Google Patents

Abstract

To provide a novel liquid crystal composition containing a near-infrared absorbing dye.SOLUTION: A polymerizable liquid crystal composition comprises a dichroic dye, and a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase, where the dichroic dye is a near-infrared absorbing dye having a maximum absorption wavelength in a wavelength region of 700 nm or more.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a polymerizable liquid crystal composition, a polarizer, and the like.

Optical elements such as polarizers are used in liquid crystal display devices. Also, it is known that a polarizer is produced using a polymerizable liquid crystal composition containing a dichroic dye, a polymerizable liquid crystal compound, and a polymerization initiator.
For example, Patent Documents 1 and 2 describe a polymerizable liquid crystal composition containing a dichroic dye and a polymerizable liquid crystal compound.

Japanese Patent No. 5923941 Japanese Patent No. 6343866

However, the dichroic dyes in the liquid crystal compositions described in Patent Documents 1 and 2 are dyes that absorb in the visible light region, and liquid crystal compositions using dyes that absorb in the near-infrared region are not known.
An object of the present invention is to provide a novel liquid crystal composition containing a near-infrared absorbing dye, which is useful for various optical elements such as a polarizer, and a polarizer using the same.

The present invention relates to the following polymerizable liquid crystal composition.
A polymerizable liquid crystal composition comprising a dichroic dye and a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase, wherein the dichroic dye is a near-infrared absorbing dye having a maximum absorption wavelength in a wavelength region of 700 nm or more. A polymerizable liquid crystal composition.

ADVANTAGE OF THE INVENTION According to this invention, the novel liquid-crystal composition containing a near-infrared absorption dye, a polarizer using the same, etc. can be provided.

In this specification, the compound represented by formula (A1) is referred to as compound (A1). The same applies to compounds represented by other formulas. The NIR dye composed of compound (A1) is also called NIR dye (A1), and the same applies to other dyes. Further, for example, the group represented by formula (1a) is also referred to as group (1a), and the groups represented by other formulas are the same.
In the present specification, the numerical range "to" includes upper and lower limits.

In this specification, unless otherwise specified, the alkyl group may be linear, branched, cyclic, or a combination of these structures.
Unless otherwise specified, the halogen atom includes fluorine, chlorine, bromine, iodine and the like, with fluorine being preferred.
In the present specification, unless otherwise specified, an aryl group refers to a group bonded via a carbon atom that constitutes an aromatic ring of an aromatic compound, such as a benzene ring, naphthalene ring, biphenyl, and the like. A heteroaryl group refers to a group bonded via a carbon atom or a heteroatom constituting an aromatic ring of an aromatic compound having a heteroatom, such as a furan ring, a thiophene ring, a pyrrole ring, and the like.

As used herein, a squarylium compound refers to a compound having a squarylium skeleton represented by the following formula (S1) that can have a resonance structure represented by the following formula (S2) in the structural formula. As used herein, the squarylium skeleton is represented by either formula (S1) or formula (S2).

In this specification, optical properties such as maximum absorption wavelength and dichroism are measured and calculated by a visible absorption spectrometer.

<Polymerizable liquid crystal composition>
The polymerizable liquid crystal composition of the present invention (hereinafter also referred to as "the composition of the present invention") contains a dichroic dye and a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase. A dichroic dye means a dye having a property that the absorbance in the long axis direction and the absorbance in the short axis direction of the molecule are different. By including a dichroic dye in the composition of the present invention, the resulting optical element can function as a polarizer.
The dichroic dye in the composition of the present invention is a near-infrared absorbing dye having a maximum absorption wavelength in the wavelength region of 700 nm or longer. Since the dichroic dye is a near-infrared absorbing dye, a polarizer capable of absorbing polarized light in the near-infrared and infrared regions can be produced.
The wavelength region with maximum absorption wavelength is preferably above 800 nm.

The near-infrared absorbing dye preferably has a highly linear structure so that it can be aligned following the alignment of the polymerizable liquid crystal, and the aspect ratio is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably. is greater than or equal to 1.8.
The aspect ratio referred to here is defined as the ratio (L/D) of the length (L) to the diameter (D) of the cylinder with the minimum diameter inscribed by the molecule.
The aspect ratio described in the present invention can be measured and calculated by the following method. Using Gaussian 16, which is software for molecular orbital calculation manufactured by Gaussian, USA, and using B3LYP/6-31G* as a keyword, the structure of the target molecular structure is optimized. Further, from the optimized structure, the aspect ratio is calculated using Winmostar (Winmostar V10), which is simulation software manufactured by X-Ability.

The near-infrared absorbing dye is preferably a squarylium dye, and more preferably a compound represented by the following formula (X), from the viewpoint of being able to absorb near-infrared and infrared light regions of 700 nm or more.

The symbols in the formula (X) are as follows.
Ar is an aromatic monocyclic, condensed or linked ring having 5 to 14 carbon atoms.

Each of R ¹ and R ² is independently a hydrogen atom or one having 1 to 20 carbon atoms which may have a substituent and may contain an unsaturated bond, hetero atom or ring structure between carbon atoms. indicates a valent hydrocarbon group.
The monovalent hydrocarbon group may be branched, linear, or cyclic, and from the viewpoint that the squarylium dye is likely to be linear, that is, to easily exhibit dichroism, it may be linear or, as described later, R ¹ and R ² are preferably linked.
The monovalent hydrocarbon group preferably has 1 to 12 carbon atoms.
Also, R ¹ and R ² may be the same or different. Furthermore, when R ¹ and R ² are linear, R ¹ and R ² are preferably different from the viewpoint that the squarylium dye tends to be linear.

The carbon atoms constituting R ¹ and R ² , or at least one of R ¹ and R ² and Ar may be linked together to form a 3- to 10-membered heterocyclic ring together with the nitrogen atom. As a result, the squarylium dye tends to be linear, that is, it tends to exhibit dichroism.

When R ¹ and R ² form a heterocyclic ring, each of R ¹ and R ² may independently have a substituent and contain an unsaturated bond between carbon atoms, a hetero atom or a ring structure. It represents a good divalent hydrocarbon group having 1 to 20 carbon atoms.

Substituents for R ¹ and R ² include halogen atom, hydroxyl group, carboxy group, sulfo group, cyano group, amino group, N-substituted amino group, nitro group, alkoxycarbonyl group, carbamoyl group, N-substituted carbamoyl group, imide groups, and alkoxy groups having 1 to 19 carbon atoms.
In addition, when R ¹ and R ² have a substituent, the number of carbon atoms of the substituent is included in the number of carbon atoms of R ¹ and R ² .

Substituents for R ¹ and R ² further include cyclic alkyl groups and aryl groups. The aryl group is preferably a phenyl group optionally having 1 to 5 substituents or a naphthyl group optionally having 1 to 7 substituents. Substituents which may substitute the hydrogen atoms of the phenyl group and naphthyl group include an alkyl group having 1 to 12 carbon atoms which may contain an unsaturated bond or an oxygen atom between carbon atoms, an alkoxy group, or an alkyl An amino group (wherein the alkyl group has 1 to 12 carbon atoms) can be mentioned. Phenyl and naphthyl groups are preferably unsubstituted or substituted with 1 to 3 hydrogen atoms, and preferred substituents include methyl, t-butyl, dimethylamino and methoxy groups.

The heteroatom for R ¹ and R ² is preferably an oxygen atom or a nitrogen atom.

When R ¹ and R ² contain an alicyclic ring or aromatic ring in the main chain or side chain, the alicyclic ring preferably has 3 to 10 carbon atoms. The number of carbon atoms in the aromatic ring is preferably 4-14.

The substituents on R ¹ and R ² may also be polymerizable groups for copolymerization with polymerizable liquid crystal compounds.

When R ¹ and R ² are linked together to form a heterocyclic ring together with a nitrogen atom, the number of members of the heterocyclic ring is 4 to 6 from the viewpoint that the squarylium dye is likely to be linear, that is, from the viewpoint that dichroism is likely to be exhibited. is preferred.
In such a heterocyclic ring, one of the hydrogen atoms bonded to the carbon atom farthest from the nitrogen atom may have an unsaturated bond or heteroatom between carbon atoms having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, and further Preferably, it may be substituted with 3 to 8 alkyl groups.
In such a heterocyclic ring, the carbon atom farthest from the nitrogen atom is replaced with a nitrogen atom, and the hydrogen atom bonded to the nitrogen atom may have an unsaturated bond or a heteroatom between carbon atoms. to 12, preferably 1 to 8, more preferably 3 to 8 alkyl groups may be substituted.
The alkyl group may be branched, straight-chain, or cyclic, but a straight-chain is preferable from the viewpoint that the squarylium dye readily exhibits dichroism. Also, some or all of the hydrogen atoms in the heterocyclic ring may be substituted with halogen atoms, in which case some or all of the hydrogen atoms bonded to carbon atoms not adjacent to the nitrogen atom are substituted with halogen atoms. preferably.

When at least one of R ¹ and R ² and the carbon atoms constituting Ar are linked to each other to form a heterocyclic ring together with the nitrogen atom, the heterocyclic ring preferably has 5 to 7 members. In such a heterocyclic ring, one of the hydrogen atoms bonded to the carbon atoms adjacent to the nitrogen atom may have an unsaturated bond or a heteroatom between the carbon atoms having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, and further preferably substituted with an alkyl group of 3 to 8, and some or all of the remaining hydrogen atoms are substituted with an alkyl group of 1 to 4 carbon atoms which may have an unsaturated bond or heteroatom between carbon atoms may be The alkyl group may be branched, straight-chain, or cyclic, but a straight-chain is preferable from the viewpoint that the squarylium dye readily exhibits dichroism. Also, some or all of the hydrogen atoms in the heterocyclic ring may be substituted with halogen atoms, in which case some or all of the hydrogen atoms bonded to carbon atoms not adjacent to the nitrogen atom are substituted with halogen atoms. preferably.

The two R ^1s may be different on the left and right sides of the squarylium skeleton, but it is preferable that the right and left sides are the same from the viewpoint of ease of production. The same applies to R ² and Ar. Moreover, the same applies to symbols after this. That is, the two symbols in the chemical formula may be different on the left and right sides of the squarylium skeleton, but from the viewpoint of ease of production, it is preferable that the left and right sides are the same.

Ar may have one or more substituents. Here, the substituent is a halogen atom, a hydroxyl group, or a substituent from the viewpoint that dichroism is easily expressed when the ratio of the molecular length in the short axis direction to the long axis direction (aspect ratio) of the squarylium dye is large. It is preferably selected from monovalent organic groups R ^Ar having 1 to 9 carbon atoms which may have The number of carbon atoms in R ^Ar and the number of carbon atoms in the substituent of R ^Ar are not included in the number of carbon atoms in Ar. R ^Ar preferably has 1 to 7 carbon atoms, more preferably 1 to 5 carbon atoms.
A halogen atom includes a chlorine atom, a fluorine atom, and an iodine atom.
The monovalent organic group R ^Ar includes alkyl groups, alkoxy groups, acyloxy groups, araryl groups, amino groups, alkenyl groups, alkynyl groups, imino groups, cyano groups, carbonyl groups, aryl groups, heteroaryl groups and the like.
R ^Ar may have a substituent. The number of carbon atoms in the substituent is included in the number of carbon atoms in R ^Ar .

As the squarylium dye, compounds represented by any one of the following formulas (I) to (VI) are preferable. The squarylium dye may contain one or more compounds.

<Squarylium dye (I)>

[The symbols in the above formula are as follows.
R ¹¹ and R ²¹ are each independently a hydrogen atom, an optionally substituted alkyl group or an alkoxy group having 1 to 20 carbon atoms which may contain an unsaturated bond or a hetero atom between carbon atoms; an acyloxy group having 1 to 19 carbon atoms, an aryl group having 6 to 11 carbon atoms, or an araryl group having 7 to 18 carbon atoms, optionally having a substituent and having an oxygen atom between the carbon atoms indicates
R ³¹ and R ⁵¹ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group or an alkoxy group having 1 to 8 carbon atoms, an acyloxy group having 1 to 8 carbon atoms, an aryl group having 6 to 9 carbon atoms, an araryl group having 7 to 9 carbon atoms which may have a substituent and which may have an oxygen atom between the carbon atoms, —NR ^31a R ^31b (R ^31a and R ^31b are each independently a hydrogen atom, Alkyl group having 1 to 4 carbon atoms, -C(=O)-R ^31c (R ^31c may have a hydrogen atom, a halogen atom, a hydroxyl group, a substituent, an unsaturated bond between carbon atoms, an oxygen atom , a hydrocarbon group having 1 to 8 carbon atoms which may contain a saturated or unsaturated ring structure), —NHR ^31d , or —SO ₂ —R ^31d (R ^31d has one or more hydrogen atoms each substituted with a halogen atom , a hydroxyl group, a carboxy group, a sulfo group, or a cyano group, and may contain an unsaturated bond between carbon atoms, an oxygen atom, a saturated or unsaturated ring structure, and a hydrocarbon group having 1 to 8 carbon atoms. ), or a group represented by formula (S) below (R ^31e and R ^31f independently represent a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 3 carbon atoms. k is 2 or 3.).

R ⁴¹ and R ⁶¹ each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl or alkoxy group having 1 to 8 carbon atoms, an acyloxy group having 1 to 8 carbon atoms, an aryl group having 6 to 9 carbon atoms, Alternatively, it represents an araryl group having 7 to 9 carbon atoms which may have a substituent and which may have an oxygen atom between carbon atoms.
R ¹¹ and R ²¹ , R ¹¹ and R ⁴¹ , and R ²¹ and R ⁶¹ are each linked together with a nitrogen atom to form a 4- to 6-membered heterocyclic ring A1, a 5- to 7-membered heterocyclic ring B1, and A 5- to 7-membered heterocyclic ring C1 may be formed. ]

When R ¹¹ and R ²¹ are alkyl groups, they are preferably linear from the viewpoint that the squarylium dye easily exhibits dichroism.

R ¹¹ and R ²¹ when heterocyclic ring A1 is formed represent an alkylene group having 3 to 5 carbon atoms or an alkyleneoxy group having 2 to 4 carbon atoms as the divalent group —Q ¹ — to which they are bonded. . Here, in the heterocyclic ring composed of a nitrogen atom and Q1, ^one of the hydrogen atoms bonded to the carbon atom farthest from the nitrogen atom may have an unsaturated bond or heteroatom between carbon atoms. It may be substituted with 1 to 12, preferably 1 to 8, more preferably 3 to 8 alkyl groups. The alkyl group is preferably linear from the viewpoint that the squarylium dye easily exhibits dichroism. Also, some or all of the hydrogen atoms in the heterocyclic ring may be substituted with halogen atoms, in which case some or all of the hydrogen atoms bonded to carbon atoms not adjacent to the nitrogen atom are substituted with halogen atoms. preferably.

R ¹¹ and R ⁴¹ when the heterocycle B1 is formed, and R ²¹ and R ⁶¹ when the heterocycle C1 is formed are the divalent groups —X ¹ —Y ¹ — and — As X ² -Y ² - (X ¹ and X ² are on the nitrogen-bonding side), X ¹ and X ² are groups represented by the following formula (1x) or (2x), and Y ¹ and Y ² are each A group represented by any one of the following formulas (1y) to (5y). When each of X ¹ and X ² is a group represented by the following formula (2x), each of Y ¹ and Y ² may be a single bond, in which case an oxygen atom may be present between the carbon atoms. .

In formula (1x), four Zs are each independently a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms or an alkoxy group, or -Nx ³⁸ x ³⁹ (x ³⁸ and x ³⁹ are each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms). x ³¹ to x ³⁶ each independently represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 10 carbon atoms, and x ³⁷ represents an alkyl group having 1 to 6 carbon atoms or an represents an aryl group.
R ^31a , R ^31b , R ^31c , x ³¹ to x ³⁷ , R ¹¹ when not forming a heterocyclic ring, R ²¹ , R ⁴¹ and R ⁶¹ are combined with any other of these to form 5 A membered ring or a 6-membered ring may be formed. x ³¹ and x ³⁶ and x ³¹ and x ³⁷ may be directly combined.

Substituents for R ¹¹ and R ²¹ include halogen atoms, hydroxyl groups, carboxy groups, sulfo groups, cyano groups, amino groups, N-substituted amino groups, nitro groups, alkoxycarbonyl groups, carbamoyl groups, N-substituted carbamoyl groups, An imide group and an alkoxy group having 1 to 19 carbon atoms can be mentioned.

Substituents for R ¹¹ and R ²¹ further include cyclic alkyl groups and aryl groups. The aryl group is preferably a phenyl group optionally having 1 to 5 substituents or a naphthyl group optionally having 1 to 7 substituents. Substituents which may substitute the hydrogen atoms of the phenyl group and naphthyl group include an alkyl group having 1 to 12 carbon atoms which may contain an unsaturated bond or an oxygen atom between carbon atoms, an alkoxy group, or an alkyl An amino group (wherein the alkyl group has 1 to 12 carbon atoms) can be mentioned. Phenyl and naphthyl groups are preferably unsubstituted or substituted with 1 to 3 hydrogen atoms, and preferred substituents include methyl, t-butyl, dimethylamino and methoxy groups.

When R ¹¹ and R ²¹ contain an alicyclic ring or aromatic ring in the main chain or side chain, the alicyclic ring preferably has 3 to 10 carbon atoms. The number of carbon atoms in the aromatic ring is preferably 4-14.

The substituents for R ¹¹ and R ²¹ may further be polymerizable groups for copolymerization with polymerizable liquid crystal compounds.

Examples of compound (I) include compounds represented by any one of formulas (I-1) to (I-4).

The symbols in formulas (I-1) to (I-4) are the same as those defined in formula (I), and preferred embodiments are also the same unless otherwise specified.

In compound (I-1), R ¹¹ is preferably a hydrogen atom or a linear alkyl group having 1 to 12 carbon atoms.

In compound (I-1), X ¹ is preferably group (2x), and Y ¹ is preferably a single bond or group (1y). That is, as -Y ¹ -X ¹ -, -C(x ³¹ )(x ³² )-C(x ³³ )(x ³⁴ )- or -C(x ³⁵ )(x ³⁶ )-C(x ³¹ )(x ³² )-C(x ³³ )(x ³⁴ )- is preferred.
In this case, x ³¹ , x ³² , x ³⁵ and x ³⁶ are each independently preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or a methyl group.
Each of x ³³ and x ³⁴ is preferably independently a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

In compound (I-1), when one linear alkyl group is bonded to the carbon atom adjacent to the nitrogen atom in the heterocyclic ring, or when one linear alkyl group is bonded to the nitrogen atom, the linearity of the compound is obtained, and dichroism is likely to be expressed. From such a viewpoint, any one of R ¹¹ , x ³³ and x ³⁴ is preferably a linear alkyl group having 3 to 12 carbon atoms, more preferably 3 to 8 carbon atoms, and the remaining two are each independently A hydrogen atom or an alkyl group having 2 or less carbon atoms is preferred.

As -Y ¹ -X ¹ -, specifically, divalent organic groups represented by the following formulas (11-1) to (11-4) and (12-1) to (12-3) are mentioned.
—C(CH ₃ ) ₂ —CH(CH ₃ )— (11-1)
—C(CH ₃ ) ₂ —CH ₂ — (11-2)
-C(CH ₃ ) ₂ -CH(nC _k H _2k+1 )- (11-3) (k = 2 to 6)
-C(CH ₃ ) ₂ -C(CH ₃ )(nC _k H _2k+1 )- (11-4) (k=3-6)
—C(CH ₃ ) ₂ —CH ₂ —CH ₂ — (12-1)
—C(CH ₃ ) ₂ —CH ₂ —CH(CH ₃ )— (12-2)
—C(CH ₃ ) ₂ —CH(CH ₃ )—CH ₂ — (12-3)

In compound (I-4), R ⁵¹ is preferably a hydrogen atom or a hydroxyl group.

<Squarylium dye (II)>

[The symbols in the above formula are as follows.
Each ring Z2 is independently a 5- or 6-membered ring having 0 to 3 heteroatoms in the ring, and the hydrogen atoms of ring Z2 may be substituted.
R ¹² and R ²² each independently contain a hydrogen atom, or an unsaturated bond between carbon atoms, a hetero atom, a saturated or unsaturated ring structure, and the number of carbon atoms that may have a substituent It represents a 1-20 monovalent hydrocarbon group.
R ³² and R ⁴² each independently represent a hydrogen atom, a halogen atom, or an optionally substituted alkyl or alkoxy group having 1 to 8 carbon atoms which may contain a heteroatom between carbon atoms; show.
The carbon atoms or heteroatoms constituting R ¹² and R ²² , R ¹² and R ⁴² , and R ²² and ring Z2 are linked together with a nitrogen atom to form a 4- to 6-membered heterocyclic ring A2 and a 5- to 5-membered heterocyclic ring A2. 7 heterocycle B2 and 5- to 7-membered heterocycle C2 may be formed. The hydrogen atoms of heterocycle A2, heterocycle B2 and heterocycle C2 may be substituted. ]

Substituents for R ¹² and R ²² include halogen atoms, hydroxyl groups, carboxy groups, sulfo groups, cyano groups, amino groups, N-substituted amino groups, nitro groups, alkoxycarbonyl groups, carbamoyl groups, N-substituted carbamoyl groups, An imide group and an alkoxy group having 1 to 19 carbon atoms can be mentioned.

Substituents for R ¹² and R ²² further include cyclic alkyl or aryl groups. The aryl group is preferably a phenyl group optionally having 1 to 5 substituents or a naphthyl group optionally having 1 to 7 substituents. Substituents which may substitute the hydrogen atoms of the phenyl group and naphthyl group include an alkyl group having 1 to 12 carbon atoms which may contain an unsaturated bond or an oxygen atom between carbon atoms, an alkoxy group, or an alkyl An amino group (wherein the alkyl group has 1 to 12 carbon atoms) can be mentioned. Phenyl and naphthyl groups are preferably unsubstituted or substituted with 1 to 3 hydrogen atoms, and preferred substituents include methyl, t-butyl, dimethylamino and methoxy groups.

When R ¹² and R ²² contain an alicyclic or aromatic ring in the main chain or side chain, the alicyclic ring preferably has 3 to 10 carbon atoms. The number of carbon atoms in the aromatic ring is preferably 4-14.

The substituents for R ¹² and R ²² may also be polymerizable groups for copolymerization with polymerizable liquid crystal compounds.

Examples of compound (II) include compounds represented by any one of formulas (II-1) to (II-3). From the viewpoint of durability, compounds represented by formula (II-1), formula Compounds represented by (II-3) are particularly preferred.

In formulas (II-1) and (II-2), each of R ¹² and R ²² may independently have a hydrogen atom or a substituent, and an unsaturated bond or heteroatom between carbon atoms. It represents an alkyl group having 1 to 20 carbon atoms which may be present. R ³² , R ⁴² , R ⁵² and R ⁶² each independently represent a hydrogen atom, a halogen atom, or an optionally substituted alkyl group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms. A halogen atom is mentioned as a substituent in an alkyl group.

From the viewpoint of orientation, R ¹² and R ²² in compound (II-1) and compound (II-2) may independently have a substituent, and an unsaturated bond between carbon atoms or a heteroatom A linear alkyl group having 1 to 20 carbon atoms which may have is preferred. R ¹² is more preferably a linear alkyl group having 1 to 12 carbon atoms, particularly preferably a linear alkyl group having 3 to 8 carbon atoms. R ²² is more preferably an alkyl group having 1 to 8 carbon atoms, particularly preferably a linear alkyl group having 1 to 4 carbon atoms. R ¹² and R ²² may be the same or different, but in the case of linear alkyl groups, they are preferably different from the viewpoint of molecular linearity.

Further, the carbon atoms constituting R ¹² and R ²² in compound (II-1) and compound (II-2) may be linked to each other to form a heterocyclic ring together with the nitrogen atom, and the heterocyclic ring may be a 4-membered ring to A 6-membered ring is particularly preferred. In such a heterocyclic ring, one of the hydrogen atoms bonded to the carbon atom farthest from the nitrogen atom may have an unsaturated bond or heteroatom between carbon atoms having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, and further Preferably, it may be substituted with 3 to 8 straight-chain alkyl groups.

From the viewpoint of orientation, R ³² and R ⁴² are each preferably a hydrogen atom or a halogen atom, and particularly preferably a hydrogen atom.

In formula (II-3), R ¹² represents a hydrogen atom or an optionally substituted alkyl group having 1 to 20 carbon atoms. R ^92a to R ^92d each independently represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group having 1 or more carbon atoms, and —CR ^92a R ^92b —CR ^92c R ^{92d —whole} has 20 or less carbon atoms. R ³² , R ⁷² and R ⁸² each independently represents a hydrogen atom, a halogen atom, or an optionally substituted alkyl group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms. A halogen atom is mentioned as a substituent in an alkyl group.

From the viewpoint of orientation, R ¹² in compound (II-3) is preferably a linear alkyl group having 1 to 18 carbon atoms.

R ^92a is more preferably a hydrogen atom, a halogen atom, or an alkyl group having 1 to 18 carbon atoms which may be substituted with a halogen atom and optionally have an unsaturated bond or heteroatom between carbon atoms.
R ^92b to R ^92d are each preferably a hydrogen atom, a halogen atom, or an optionally halogen-substituted alkyl group having 1 to 5 carbon atoms.

Furthermore, in compound (II-3), when one linear alkyl group is bonded to the carbon atom adjacent to the nitrogen atom in the heterocyclic ring, or when one linear alkyl group is bonded to the nitrogen atom, the compound Linearity is obtained and dichroism is easily expressed. From this viewpoint, one of R ¹² and R ^92a is preferably a linear alkyl group having 3 to 18 carbon atoms, more preferably 3 to 12 carbon atoms, and the other is a hydrogen atom or an alkyl group having 2 or less carbon atoms. is preferably

—CR ^92a R ^92b —CR ^92c R ^92d — includes divalent organic groups represented by the following groups (13-1) to (13-9).
—CH(CH ₃ )—C(CH ₃ ) ₂ — (13-1)
—C(CH ₃ ) ₂ —CH(CH ₃ )— (13-2)
—C(CH ₃ ) ₂ —CH ₂ — (13-3)
—C(CH ₃ ) ₂ —CH(C ₂ H ₅ )— (13-4)
—CH(CH ₃ )—C(CH ₃ )(CH ₂ —CH(CH ₃ ) ₂ )— (13-5)
—CH(CH ₂ CH(CH ₃ ) ₂ )—C(CH ₃ ) ₂ — (13-6)
—CH(C _n H _2n+1 )—C(CH ₃ ) ₂ − (13-7) (n=1 to 12)
—CH(C _n H _2n+1 )—CH ₂ − (13-8) (n=1 to 12)
—C(CH ₃ )(C _n H _2n+1 )—CH ₂ − (13-9) (n=1 to 12)

R ⁷² and R ⁸² are each preferably a hydrogen atom, a halogen atom, or an optionally halogen-substituted alkyl group having 1 to 8 carbon atoms, more preferably a hydrogen atom, a halogen atom, or a methyl group.

More specific examples of compound (II-1) include the compounds shown in the table below. In addition, in the compounds shown in the following tables, the symbols on the left and right sides of the squarylium skeleton have the same meaning.

More specific examples of compound (II-3) include the compounds shown in the table below. In addition, in the compounds shown in the following tables, the symbols on the left and right sides of the squarylium skeleton have the same meaning.

Compounds (I) to (II) can be produced by known methods. Compound (I) can be produced by the methods described in US Pat. Compound (II) can be produced by the method described in International Publication No. 2017/135359.

<Squarylium dye (III)>

[The symbols in the above formula are as follows.
each of R ¹³ and R ²³ independently may have a substituent and may contain an unsaturated bond between carbon atoms, a hetero atom, an alicyclic ring or an aromatic ring, and an alkyl group having 1 to 20 carbon atoms; is.
R ³³ is an organic group R ^33A not essentially having an unsaturated bond or an organic group R ^33B essentially having an unsaturated bond.
^X31 is ^CR43 or N;
X ³² is S, NR ⁵³ , or O;
^X33 is S, ^NR63 , or O;
R ⁴³ is a hydrogen atom, a halogen atom, a sulfo group, a hydroxyl group, a cyano group, a nitro group, a carbonyl structure-containing monovalent organic group, a phosphate group, a silyl group, a thiol group, a sulfide group, an amide structure-containing monovalent organic group, a sulfone amide group, urea group, urethane structure-containing monovalent organic group, optionally substituted C1-C9 alkyl group, optionally substituted C2-C9 alkenyl group, substituent an alkynyl group having 2 to 9 carbon atoms which may have a substituent, an aryl group having 6 to 9 carbon atoms which may have a substituent, a heteroaryl group having 3 to 9 carbon atoms which may have a substituent, an optionally substituted alkoxy group having 1 to 9 carbon atoms, an optionally substituted acyloxy group having 2 to 9 carbon atoms, or —N(R ^43g ) ₂ (R ^43g is a hydrogen atom or It is an optionally substituted alkyl group having 1 to 4 carbon atoms.).
R ⁵³ and R ⁶³ are each independently a hydrogen atom, a monovalent organic group containing a carbonyl structure, a sulfo group, or an optionally substituted alkyl group having 1 to 9 carbon atoms.
R ¹³ may be combined with R ²³ , R ³³ , X ³¹ , X ³² or X ³³ to form a 3-6 membered ring.
R ²³ may be combined with R ¹³ , R ³³ , X ³¹ , X ³² or X ³³ to form a 3-6 membered ring.
R ³³ may be combined with X ³¹ , X ³² or X ³³ to form a 5- to 7-membered ring. ]

Substituents for R ¹³ and R ²³ include halogen atoms, hydroxyl groups, carboxy groups, sulfo groups, cyano groups, amino groups, N-substituted amino groups, nitro groups, alkoxycarbonyl groups, carbamoyl groups, N-substituted carbamoyl groups, An imide group and an alkoxy group having 1 to 19 carbon atoms can be mentioned.

Substituents for R ¹³ and R ²³ further include cyclic alkyl groups and aryl groups. The aryl group is preferably a phenyl group optionally having 1 to 5 substituents or a naphthyl group optionally having 1 to 7 substituents. Substituents which may substitute the hydrogen atoms of the phenyl group and naphthyl group include an alkyl group having 1 to 12 carbon atoms which may contain an unsaturated bond or an oxygen atom between carbon atoms, an alkoxy group, or an alkyl An amino group (wherein the alkyl group has 1 to 12 carbon atoms) can be mentioned. Phenyl and naphthyl groups are preferably unsubstituted or substituted with 1 to 3 hydrogen atoms, and preferred substituents include methyl, t-butyl, dimethylamino and methoxy groups.

When R ¹³ and R ²³ contain an alicyclic or aromatic ring in the main chain or side chain, the alicyclic ring preferably has 3 to 10 carbon atoms. The number of carbon atoms in the aromatic ring is preferably 4-14.

The substituents for R ¹³ and R ²³ may also be polymerizable groups for copolymerization with polymerizable liquid crystal compounds.

The carbon number of R ¹³ includes 1-20. The number of carbon atoms in R ¹³ is preferably 2 to 20, more preferably 2 to 16, even more preferably 2 to 12, in the case of a linear chain. The number of carbon atoms in R ¹³ is preferably 3 to 20, more preferably 3 to 16, and even more preferably 3 to 12 in the case of a branched chain.
The carbon number of R ²³ includes 1-20. The number of carbon atoms in R ²³ is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4 when linear, from the viewpoint of the degree of orientation. The number of carbon atoms in R ²³ is preferably 3 to 10, more preferably 3 to 6, in the case of a branched chain.
When R ¹³ and R ²³ have a substituent, and when the main chain or side chain contains an alicyclic ring or an aromatic ring, the carbon number of the substituent, the alicyclic ring and the aromatic ring are included in the above number of carbon atoms.

R ¹³ and R ²³ may be the same or different. From the viewpoint of the degree of orientation, it is preferable that R ¹³ and R ²³ are different when chain-like.

From the viewpoint of orientation, R ¹³ and R ²³ are preferably linear.

More preferably, R ¹³ and R ²³ are groups selected from groups (1b) to (5b) and groups (1c) to (2c).
—CH(C _n H _2n+1 ) ₂ (1b)
-C(C _n H _2n+1 ) ₃ (1c)
—CH ₂ —CH(C _n H _2n+1 ) ₂ (2b)
—CH ₂ —C(C _n H _2n+1 ) ₃ (2c)
—(CH ₂ ) ₂ —CH(C _n H _2n+1 ) ₂ (3b)
—(CH ₂ ) ₃ —CH(C _n H _2n+1 ) ₂ (4b)
—(CH ₂ ) _m —CH ₃ (5b)

However, in formulas (1b) to (4b) and formulas (1c) to (2c), n is an integer of 1 to 10, preferably 1 to 8, more preferably 1 to 4. However, the number of carbon atoms in groups (1b) to (4b) and groups (1c) to (2c) should be within the range of 1-20. Two C _n H 2n+1 in formulas (1b) to (4b) and three C _n H _{2n +1} in formulas (1c) to (2c) may each be linear or branched, They may be the same or different. In formula (5b), m is an integer of 0 to 19, preferably 1 to 19, more preferably 2 to 19, and even more preferably 4 to 19. Furthermore, groups (1b) to (5b) and groups (1c) to (2c) may have an oxygen atom between carbon atoms.

Further, when R ¹³ and R ²³ are linked to each other to form a heterocyclic ring together with a nitrogen atom, the divalent group -Q ³ - to which R ¹³ and R ²³ are linked is an alkylene group having 3 to 5 carbon atoms or a carbon represents an alkyleneoxy group of numbers 2 to 4; Here, in the heterocyclic ring composed of a nitrogen atom and ^Q3 , one of the hydrogen atoms bonded to the carbon atom farthest from the nitrogen atom may have an unsaturated bond or heteroatom between carbon atoms. It may be substituted with 1 to 12, preferably 1 to 8, more preferably 3 to 8 alkyl groups. The alkyl group is preferably linear from the viewpoint that the squarylium dye easily exhibits dichroism. Also, some or all of the hydrogen atoms in the heterocyclic ring may be substituted with halogen atoms, in which case some or all of the hydrogen atoms bonded to carbon atoms not adjacent to the nitrogen atom are substituted with halogen atoms. preferably.

R ³³ is an organic group R ^33A not essentially having an unsaturated bond or an organic group R ^33B essentially having an unsaturated bond.
The organic group R ^33A which does not necessarily have an unsaturated bond is a hydrogen atom, a halogen atom, a hydroxyl group, or an alkyl group which may have a substituent and which may contain an unsaturated bond or an oxygen atom between carbon-carbon atoms. , an alkoxy group, an aryl group or an araryl group.
The organic group R ^33B essentially having an unsaturated bond is an optionally substituted alkenyl group having 2 or more carbon atoms, an optionally substituted alkynyl group having 2 or more carbon atoms, and a substituted imino group having 1 or more carbon atoms, cyano group, organic group having 1 or more carbon atoms and optionally having a carbonyl structure and optionally having a substituent, aryl group having 6 to 9 carbon atoms and optionally having a substituent , or an optionally substituted heteroaryl group having 3 to 9 carbon atoms.
R ³³ may be linked with X ³¹ , X ³² or X ³³ to form a ring. As the ring, a ring having 5 to 7 members is preferable. Moreover, the ring may have a substituent.

Examples of substituents for R ^33A include halogen atoms, hydroxyl groups, carboxy groups, sulfo groups, cyano groups, amino groups, N-substituted amino groups, nitro groups, alkoxycarbonyl groups, carbamoyl groups, N-substituted carbamoyl groups, imide groups, An alkoxy group having 1 to 8 carbon atoms can be mentioned. When R ^33A is an aryl group or an araryl group, the substituent is a hydrogen atom bonded to an aromatic ring or a group that substitutes a hydrogen atom of an alkyl group thereof, and includes an aryl group in addition to the above substituents.

When R ^33A is an alkyl group or an alkoxy group, it preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms. When R ^33A is an aryl group, it preferably has 6 to 9 carbon atoms. When R ^33A is an araryl group, it preferably has 7 to 9 carbon atoms.
When R ^33A has a substituent, the carbon number of the substituent is included in the carbon number of R ^33A .

R ^33A is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, particularly preferably a hydrogen atom, from the viewpoint of light stability and orientation.

Substituents for the organic group R ^33B essentially having an unsaturated bond include a halogen atom, a hydroxyl group, a carbonyl structure-containing monovalent organic group, a phosphate group, a sulfo group, a cyano group, an amino group, an N-substituted amino group, a nitro group, alkoxycarbonyl group, carbamoyl group, N-substituted carbamoyl group, imide group, thiol group, sulfide group, alkoxy group having 1 to 8 carbon atoms, alkyl group having 1 to 8 carbon atoms, aryl group having 6 to 8 carbon atoms , a heteroaryl group having 3 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, a silyl group, and a halogenated alkyl group having 1 to 8 carbon atoms.
When R ^33B has a substituent, the carbon number of the substituent is included in the carbon number of R ^33B .

When R ^33B is an alkenyl group, it has 2 or more carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, still more preferably 2 to 4 carbon atoms.
As the alkenyl group, a group represented by the following formula (3-1) is preferable.

R ^3a , R ^3b , and R ^3c each independently represent a hydrogen atom, a halogen atom, a formyl group, a carboxy group, a sulfo group, a cyano group, an amino group, an N-substituted amino group, a nitro group, an alkoxycarbonyl group, or a carbamoyl group. , N-substituted carbamoyl group, imide group, sulfide group, alkoxy group having 1 to 7 carbon atoms, alkyl group having 1 to 7 carbon atoms, aralkyl group having 6 to 7 carbon atoms, number of carbon atoms which may have a substituent 6 to 7 aryl group, optionally substituted heteroaryl group having 3 to 7 carbon atoms, alkenyl group optionally having 2 to 7 carbon atoms, optionally having substituent(s) Alkynyl groups having 2 to 7 carbon atoms, triorganosilyl groups having 3 to 7 carbon atoms (trimethylsilyl group, triphenylsilyl group, t-butyldiphenylsilyl group, etc.), trialkoxysilyl groups having 3 to 7 carbon atoms (trimethoxy silyl group, dimethoxyethoxysilyl group, etc.), or a halogenated alkyl group having 1 to 7 carbon atoms. R ^3b may combine with R ^3a or R ^3c to form a 3- to 6-membered ring which may contain a heteroatom, in which case the ring may have a substituent.

Examples of substituents in the ring formed by connecting an aryl group, a heteroaryl group, an alkenyl group, an alkynyl group, and ^R3b with ^R3a or ^R3c include a halogen atom, a formyl group, a carboxy group, a sulfo group, an amino group, N -substituted amino group, nitro group, alkoxycarbonyl group, carbamoyl group, N-substituted carbamoyl group, imide group, sulfide group, alkoxy group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms, 3 to 6 carbon atoms triorganosilyl group (trimethylsilyl group, etc.), C 3-6 trialkoxysilyl group (trimethoxysilyl group, dimethoxyethoxysilyl group, etc.), or C 1-6 halogenated alkyl group.

Group (3-1) preferably includes the following structures.

When R ^33B is an alkynyl group, it has 2 or more carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, still more preferably 2 to 4 carbon atoms.
As the alkynyl group, a group represented by the following formula (3-2) is preferable.

R ^3d is hydrogen atom, halogen atom, formyl group, carboxy group, sulfo group, cyano group, amino group, N-substituted amino group, nitro group, alkoxycarbonyl group, carbamoyl group, N-substituted carbamoyl group, imide group, sulfide group, an alkoxy group having 1 to 7 carbon atoms, an alkyl group having 1 to 7 carbon atoms, an aralkyl group having 6 to 7 carbon atoms, an aryl group having 6 to 7 carbon atoms which may have a substituent, a substituent a heteroaryl group having 3 to 7 carbon atoms which may be substituted, an alkenyl group having 2 to 7 carbon atoms which may have a substituent, an alkynyl group having 2 to 7 carbon atoms which may have a substituent, a carbon number triorganosilyl groups of 3 to 7 (trimethylsilyl group, etc.), trialkoxysilyl groups of 3 to 7 carbon atoms (trimethoxysilyl group, dimethoxyethoxysilyl group, etc.), or halogenated alkyl groups of 1 to 7 carbon atoms. .

Substituents in the aryl group, heteroaryl group, alkenyl group and alkynyl group include halogen atoms, formyl groups, carboxy groups, sulfo groups, amino groups, N-substituted amino groups, nitro groups, alkoxycarbonyl groups, carbamoyl groups, N -substituted carbamoyl group, imide group, sulfide group, alkoxy group having 1 to 5 carbon atoms, triorganosilyl group having 3 to 5 carbon atoms (trimethylsilyl group, etc.), trialkoxysilyl group having 3 to 5 carbon atoms (trimethoxysilyl group, dimethoxyethoxysilyl group, etc.), or a halogenated alkyl group having 1 to 5 carbon atoms.

Group (3-2) preferably includes the following structures.

When R ^33B is an imino group, it has 1 or more carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms.
As the imino group, a group represented by the following formula (3-3) is preferable.

R ^3e and R ^3f each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a formyl group, a carboxy group, a sulfo group, a cyano group, an amino group, an N-substituted amino group, a nitro group, an alkoxycarbonyl group, a carbamoyl group, N-substituted carbamoyl group, imide group, sulfide group, alkoxy group having 1 to 8 carbon atoms, alkyl group having 1 to 8 carbon atoms, aralkyl group having 6 to 8 carbon atoms, optionally substituted 6 carbon atoms ~8 aryl group, optionally substituted C3-10 heteroaryl group, optionally substituted C2-8 alkenyl group, optionally substituted carbon alkynyl group having 2 to 8 carbon atoms, triorganosilyl group having 3 to 8 carbon atoms (trimethylsilyl group, etc.), trialkoxysilyl group having 3 to 8 carbon atoms (trimethoxysilyl group, dimethoxyethoxysilyl group, etc.), or carbon It is a halogenated alkyl group of number 1-8. R ^3e and R ^3f may combine to form a 3- to 6-membered ring which may contain a heteroatom, in which case the ring may have a substituent.

Aryl group, heteroaryl group, alkenyl group, alkynyl group, and substituents in the ring formed by combining R ^3e and R ^3f include halogen atom, formyl group, carboxy group, sulfo group, amino group, N-substituted amino group, nitro group, alkoxycarbonyl group, carbamoyl group, N-substituted carbamoyl group, imide group, sulfide group, alkoxy group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms, triorgano having 3 to 6 carbon atoms A silyl group (trimethylsilyl group, etc.), a C3-6 trialkoxysilyl group (trimethoxysilyl group, dimethoxyethoxysilyl group, etc.), or a C1-6 halogenated alkyl group can be mentioned.

Group (3-3) preferably includes the following structures.

When R ^33B is a cyano group, it is a group represented by the following formula (3-4).

When R ^33B is an organic group containing a carbonyl structure and having 1 or more carbon atoms and optionally having a substituent, the number of carbon atoms is 1 or more, preferably 1 to 8, more preferably 1 to 6, More preferably 1-4.
As such an organic group, a group represented by the following formula (3-5) is preferable.

R ^3g is a hydrogen atom, a hydroxyl group, a cyano group, an amino group, an N-substituted amino group, an alkoxycarbonyl group, a sulfide group, an alkoxy group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms, or 6 to 8 carbon atoms; aralkyl group, optionally substituted C6-8 aryl group, optionally substituted C3-8 heteroaryl group, optionally substituted C2 ~8 alkenyl groups, optionally substituted alkynyl groups having 2 to 8 carbon atoms, triorganosilyl groups having 3 to 8 carbon atoms (such as trimethylsilyl groups), trialkoxysilyl groups having 3 to 8 carbon atoms ( trimethoxysilyl group, dimethoxyethoxysilyl group, etc.), or a halogenated alkyl group having 1 to 8 carbon atoms.

Substituents in the aryl group, heteroaryl group, alkenyl group and alkynyl group include halogen atoms, formyl groups, carboxy groups, sulfo groups, amino groups, N-substituted amino groups, nitro groups, alkoxycarbonyl groups, carbamoyl groups, N -substituted carbamoyl group, imido group, sulfide group, alkoxy group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms, triorganosilyl group having 3 to 6 carbon atoms (trimethylsilyl group, etc.), 3 to 6 carbon atoms and a trialkoxysilyl group (trimethoxysilyl group, dimethoxyethoxysilyl group, etc.), or a halogenated alkyl group having 1 to 6 carbon atoms.

Group (3-5) preferably includes the following structures.

When R ^33B is an aryl group, it has 6-9 carbon atoms.

As the aryl group, a group represented by the following formula (3-6) is preferable.

R ^3h , R ³ⁱ , R ^3j , R ^3k and R ^3l are each independently hydrogen atom, halogen atom, hydroxyl group, formyl group, carboxy group, sulfo group, cyano group, amino group, N-substituted amino group, nitro group, alkoxycarbonyl group, carbamoyl group, N-substituted carbamoyl group, imide group, sulfide group, alkoxy group having 1 to 3 carbon atoms, alkyl group having 1 to 3 carbon atoms, optionally substituted 2 carbon atoms to 3 alkenyl groups, optionally substituted alkynyl groups having 2 to 3 carbon atoms, trimethylsilyl groups, trimethoxysilyl groups, or halogenated alkyl groups having 1 to 3 carbon atoms.
R ^3h and R ³ⁱ , R ³ⁱ and R ^3j , R ^3j and R ^3k , R ^3k and R ^3l may be linked together to form a 3- to 6-membered ring which may contain a heteroatom.

Substituents for alkenyl and alkynyl groups include halogen atoms, formyl groups, carboxy groups, sulfo groups, amino groups, N-substituted amino groups, nitro groups, alkoxycarbonyl groups, carbamoyl groups, N-substituted carbamoyl groups, and imide groups. , a sulfide group, a methoxy group, a methyl group, or a halogenated methyl group.

Group (3-6) preferably includes the following structures.

When R ^33B is a heteroaryl group, it has 3-9 carbon atoms.

As the heteroaryl group, a group represented by any one of the following formulas (3-7) to (3-9) is preferable.

X ^3a , X ^3b , X ^3c , X ^3d and X ^3e are each independently N or CR ^3m and at least one is N; R ^3m is a hydrogen atom, a halogen atom, a hydroxyl group, a formyl group, a carboxy group, a sulfo group, a cyano group, an amino group, an N-substituted amino group, a nitro group, an alkoxycarbonyl group, a carbamoyl group, an N-substituted carbamoyl group, an imide group; , a sulfide group, an alkoxy group having 1 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms, a phenyl group, a heteroaryl group having 3 to 6 carbon atoms which may have a substituent, optionally having a substituent C 2-6 alkenyl groups, optionally substituted C 2-6 alkynyl groups, C 3-6 triorganosilyl groups (such as trimethylsilyl groups), C 3-6 tri It is an alkoxysilyl group (trimethoxysilyl group, dimethoxyethoxysilyl group, etc.) or a halogenated alkyl group having 1 to 6 carbon atoms.
When X ^3a , X ^3b , X ^3c , X ^3d and X ^3e are CR ^3m , adjacent X ^3a to X ^3e are 3- to 6-membered rings Ar ³⁰ and Ar ³¹ which may be linked to each other and may contain a heteroatom. , Ar ³² , Ar ³³ , in which case the ring may have a substituent.
Substituents in the heteroaryl group, alkenyl group, alkynyl group, ring Ar ³⁰ , Ar ³¹ , Ar ³² and Ar ³³ include halogen atom, formyl group, carboxy group, sulfo group, amino group, N-substituted amino group, nitro group, alkoxycarbonyl group, carbamoyl group, N-substituted carbamoyl group, imide group, sulfide group, trimethylsilyl group, alkoxy group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms, or halogen having 1 to 4 carbon atoms alkyl group.

Group (3-7) preferably includes the following structures.

X ^3f , X ^3g and X ^3h are each independently N or CR ³ⁿ . Y ^3a is S, O or NR ^3o .
R ³ⁿ and R ^3o each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a formyl group, a carboxy group, a sulfo group, a cyano group, an amino group, an N-substituted amino group, a nitro group, an alkoxycarbonyl group, a carbamoyl group, N-substituted carbamoyl group, imide group, sulfide group, alkoxy group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms, phenyl group, optionally substituted heteroaryl group having 3 to 6 carbon atoms , an alkenyl group having 2 to 6 carbon atoms which may have a substituent group, an alkynyl group having 2 to 6 carbon atoms which may have a substituent group, a triorganosilyl group having 3 to 6 carbon atoms (trimethylsilyl group, etc.) , a trialkoxysilyl group having 3 to 6 carbon atoms (trimethoxysilyl group, dimethoxyethoxysilyl group, etc.), or a halogenated alkyl group having 1 to 6 carbon atoms.
When X ^3f , X ^3g and X ^3h are CR ³ⁿ and Y ^3a is NR ^3o , adjacent X ^3f , X ^3g , X ^3h and Y ^3a may be linked to each other and may contain a heteroatom. 6 rings Ar ³⁴ , Ar ³⁵ and Ar ³⁶ may be formed, in which case the rings may have a substituent.
Substituents in the heteroaryl group, alkenyl group, alkynyl group, ring Ar ³⁴ , Ar ³⁵ and Ar ³⁶ include halogen atom, formyl group, carboxy group, sulfo group, amino group, N-substituted amino group, nitro group and alkoxy group. carbonyl group, carbamoyl group, N-substituted carbamoyl group, imide group, sulfide group, trimethylsilyl group, alkoxy group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms, or halogenated alkyl group having 1 to 4 carbon atoms is mentioned.

Group (3-8) preferably includes the following structures.

X ³ⁱ , X ^3j and X ^3k are each independently N or CR ^3p . Y ^3b is S, O or NR ^3q . R ^3p and R ^3q each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a formyl group, a carboxy group, a sulfo group, a cyano group, an amino group, an N-substituted amino group, a nitro group, an alkoxycarbonyl group, a carbamoyl group, N-substituted carbamoyl group, imide group, sulfide group, alkoxy group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms, phenyl group, optionally substituted heteroaryl group having 3 to 6 carbon atoms , an alkenyl group having 2 to 6 carbon atoms which may have a substituent group, an alkynyl group having 2 to 6 carbon atoms which may have a substituent group, a triorganosilyl group having 3 to 6 carbon atoms (trimethylsilyl group, etc.) , a trialkoxysilyl group having 3 to 6 carbon atoms (trimethoxysilyl group, dimethoxyethoxysilyl group, etc.), or a halogenated alkyl group having 1 to 6 carbon atoms.
When X ³ⁱ , X ^3j , and X ^3k are CR ^3p and Y ^3b is NR ^3q , adjacent X ³ⁱ , X ^3j , X ^3k , and Y ^3b may be linked to each other and may contain a heteroatom. 6 rings Ar ³⁷ , Ar ³⁸ and Ar ³⁹ may be formed, in which case the rings may have a substituent.
Substituents in the aryl group, heteroaryl group, alkenyl group, alkynyl group, ring Ar ³⁷ , Ar ³⁸ and Ar ³⁹ include halogen atom, formyl group, carboxy group, sulfo group, amino group, N-substituted amino group, nitro group, alkoxycarbonyl group, carbamoyl group, N-substituted carbamoyl group, imide group, sulfide group, trimethylsilyl group, alkoxy group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms, or halogen having 1 to 4 carbon atoms alkyl group.

Group (3-9) preferably includes the following structures.

In formula (III), X ³¹ is CR ⁴³ or N. X ³² is S, NR ⁵³ , or O; ^X33 is S, ^NR63 , or O;

R ⁴³ is a hydrogen atom, a halogen atom, a sulfo group, a hydroxyl group, a cyano group, a nitro group, a carbonyl structure-containing monovalent organic group, a phosphate group, a silyl group, a thiol group, a sulfide group, an amide structure-containing monovalent organic group, a sulfone amide group, urea group, urethane structure-containing monovalent organic group, optionally substituted C1-C9 alkyl group, optionally substituted C2-C9 alkenyl group, substituent an alkynyl group having 2 to 9 carbon atoms which may have a substituent, an aryl group having 6 to 9 carbon atoms which may have a substituent, a heteroaryl group having 3 to 9 carbon atoms which may have a substituent, an optionally substituted alkoxy group having 1 to 9 carbon atoms, an optionally substituted acyloxy group having 2 to 9 carbon atoms, or —N(R ^43g ) ₂ (R ^43g is a hydrogen atom or It is an optionally substituted alkyl group having 1 to 4 carbon atoms.).

When R ⁴³ is an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heteroaryl group, an alkoxy group, an acyloxy group, or -N(R ^43g ) ₂ , R ⁴³ and any one of R ¹³ to R ³³ They may be linked to form a 3- to 6-membered ring. Moreover, the said ring may have a substituent.

Examples of substituents for R ⁴³ include a halogen atom, a hydroxyl group, a monovalent organic group containing a carbonyl structure, a phosphoric acid group, a sulfo group, a cyano group, an amino group, an N-substituted amino group, a nitro group, an alkoxycarbonyl group, a carbamoyl group, N-substituted carbamoyl group, imide group, thiol group, sulfide group, alkoxy group having 1 to 8 carbon atoms, alkyl group having 1 to 8 carbon atoms, aryl group having 6 to 8 carbon atoms, heteroaryl group having 3 to 8 carbon atoms groups, alkenyl groups having 2 to 8 carbon atoms, alkynyl groups having 2 to 8 carbon atoms, silyl groups, and halogenated alkyl groups having 1 to 8 carbon atoms.
When R ⁴³ has a substituent, the carbon number of the substituent is included in the carbon number of R ⁴³ .

A fluorine atom is preferred as the halogen atom for R ⁴³ .

The carbonyl structure-containing monovalent organic group for R ⁴³ is preferably -C(=O)-R ^43a . R ^43a is a hydrogen atom, an optionally substituted C 1-8 alkyl group, or an optionally substituted C 1-8 alkoxy group, methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, isopropyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, methoxy group, ethoxy group, propoxy group, butoxy group, hexyloxy group, octyloxy group, isopropoxy group , isobutoxy group and 2-ethylhexyloxy group are preferred.

The silyl group for R ⁴³ is preferably —Si(R ^43b ) ₃ . R ^43b is a hydrogen atom or an optionally substituted alkyl group having 1 to 3 carbon atoms, preferably a methyl group, an ethyl group, a propyl group or an isopropyl group. The three R ^43b may be the same or different.

-SR ^43c is preferred as the sulfide group for R ⁴³ . R ^43c is a hydrogen atom or an optionally substituted alkyl group having 1 to 9 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl, octyl, isopropyl, t-butyl The 2-ethylhexyl group is preferred.

As the amide structure-containing monovalent organic group for R ⁴³ , -C(=O)-NH-R ^43d is preferable. R ^43d is a hydrogen atom or an optionally substituted alkyl group having 1 to 8 carbon atoms, such as methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, isopropyl group, t-butyl The 2-ethylhexyl group is preferred.

The sulfonamide group for R ⁴³ is preferably —SO ₂ —N(R ^43e ) ₂ . R ^43e is a hydrogen atom or an optionally substituted alkyl group having 1 to 4 carbon atoms, preferably a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group or a t-butyl group. Two R ^43e may be the same or different.

The urethane structure-containing monovalent organic group for R ⁴³ is preferably -NH-C(=O) ^{OR 43f} . R ^43f is a hydrogen atom or an optionally substituted alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl, octyl, isopropyl, t-butyl The 2-ethylhexyl group is preferred.

The alkyl group having 1 to 9 carbon atoms for R ⁴³ is preferably a methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, isopropyl group, isobutyl group, t-butyl group or 2-ethylhexyl group. .

The alkenyl group having 2 to 9 carbon atoms in R ⁴³ includes vinyl group, 1-propenyl group, isobutenyl group, styryl group, 2-fluorovinyl group, 2,2-difluorovinyl group, 3,3,3-trifluoro A propenyl group is preferred.

The alkynyl group having 2 to 9 carbon atoms for R ⁴³ is preferably an acetylenyl group, 1-propynyl group, trimethylsilylethynyl group, triethylsilylethynyl group, triisopropylsilylethynyl group, or t-butyldimethylsilylethynyl group.

The aryl group having 6 to 9 carbon atoms for R ⁴³ includes a phenyl group, 4-methoxyphenyl group, 3,4,5-trifluorophenyl group, 4-trifluoromethylphenyl group, 2,5-dimethylphenyl group, A 3-nitrophenyl group is preferred.

The heteroaryl group having 3 to 9 carbon atoms for R ⁴³ includes a pyridyl group, a pyrimidyl group, a quinolyl group, a furyl group, a thienyl group, an oxazolyl group, an imidazolyl group, a thiazolyl group, a benzoxazolyl group, a benzimidazolyl group, and a benzthiazolyl group. groups are preferred.

The alkoxy group having 1 to 9 carbon atoms for R ⁴³ is preferably methoxy, ethoxy, propoxy, butoxy, hexyloxy, octyloxy, isopropoxy, isobutoxy and 2-ethylhexyloxy.

The acyloxy group having 2 to 9 carbon atoms in R ⁴³ is preferably an acetoxy group, a propionyloxy group, a butyryloxy group, an isobutyryloxy group and a benzoyloxy group.

Two R ^43g in —N(R ^43g ) ₂ in R ⁴³ may be the same or different. Also, two R ^43g may be linked together to form a ring. —N(R ^43g ) ₂ is preferably a dimethylamino group, a diethylamino group, an ethylisopropylamino group, or a morpholino group.

X ³² is S, NR ⁵³ , or O;
R ⁵³ is a hydrogen atom, a monovalent organic group containing a carbonyl structure, a sulfo group, or an optionally substituted alkyl group having 1 to 9 carbon atoms, and is a hydrogen atom, a methyl group, an ethyl group, an isobutyl group, a 2 -ethylhexyl group, benzyl group, t-butoxycarbonyl group, benzyloxycarbonyl group, 9-fluorenylmethyloxycarbonyl group, allyloxycarbonyl group, 2,2,2-triethoxycarbonyl group, 2-nitrobenzenesulfonyl group preferable.
Substituents include the same substituents as those for R ⁴³ .

When R ⁵³ is an optionally substituted alkyl group having 1 to 9 carbon atoms, R ⁵³ may be linked to any one of R ¹³ to R ³³ to form a 3- to 6-membered ring.

^X33 is S, ^NR63 , or O;
R ⁶³ is a hydrogen atom, a monovalent organic group containing a carbonyl structure, a sulfo group, or an optionally substituted alkyl group having 1 to 9 carbon atoms, and is a hydrogen atom, a methyl group, an ethyl group, an isobutyl group, a 2 -ethylhexyl group, benzyl group, t-butoxycarbonyl group, benzyloxycarbonyl group, 9-fluorenylmethyloxycarbonyl group, allyloxycarbonyl group, 2,2,2-triethoxycarbonyl group, 2-nitrobenzenesulfonyl group preferable.
Substituents include the same substituents as those for R ⁴³ .

When R ⁶³ is an alkyl group, R ⁶³ may be linked with R ⁴³ to form a 3-6 membered ring.

In Formula (III), X ³¹ , X ³² and X ³³ include the following combinations.

From the viewpoint of ease of synthesis, preferred combinations are (X ³¹ , X ³² , X ³³ ) = (CR ⁴³ , S, S), (CR ⁴³ , S, O), (CR ⁴³ , O, S), ( CR ⁴³ , O, O), (CR ⁴³ , NR ⁵³ , S), (CR ⁴³ , NR ⁵³ , O), and a more preferred combination is (X ³¹ , X ³² , X ³³ )=(CR ⁴³ , S, S), ( ^CR43 , S, O), ( ^CR43 , ^NR53 , S), ( ^CR43 , ^NR53 , O).

As the squarylium compound represented by formula (III), the squarylium compound represented by formula (III-1) below and the squarylium compound represented by formula (III-2) below are selected from the standpoint of increasing molecular linearity in addition to ease of synthesis. A squarylium compound represented by is preferred.

R ¹³ , R ²³ , R ^33A , R ^33B and R ⁴³ are respectively the same as R ¹³ , R ²³ , R ^33A , R ^33B and R ⁴³ in Formula (III) including preferred embodiments.

More specific examples of compound (III-1) include the compounds shown in the table below. In addition, in the compounds shown in the following tables, the symbols on the left and right sides of the squarylium skeleton have the same meaning.

More specific examples of compound (III-2) include the compounds shown in the table below. In addition, in the compounds shown in the following tables, the symbols on the left and right sides of the squarylium skeleton have the same meaning.

The squarylium compound (III) can be synthesized by a known production method or a production method described below.

Squarylium compound (III-1) can be produced, for example, by the method described in WO2019/230570.

Scheme (FB) shows a method for obtaining a squarylium compound (III-B) in which R ³³ in the squarylium compound (III) is R ^33B .

Step A (step (A)) is a reaction for converting a carboxylic acid into a dialkylamine, and the details are shown in the scheme below.
HetAr in the following scheme means heteroaryl. Moreover, azide is preferably diphenylphosphoryl azide. _N alkylation is preferably an SN2 reaction using an alkyl halide and a base or a reductive amination reaction using an aldehyde and a reducing agent.

Step B (step (B)) is a reaction for converting halogen to various substituents, and includes cross-coupling reaction, Heck reaction, formylation, and Wittig reaction, Knevenagel reaction, Henry reaction, alkyl A nucleophilic addition reaction of a metal reactant or the like can be used, but is not limited thereto.

The starting material (a2-1) of scheme (FB) can be obtained, for example, from a known compound by the synthesis method described below.

A method for synthesizing a compound, wherein X ³¹ , X ³² and R in the starting material (a2-1) are as follows:
Compound (a2-1-1): (X ³¹ , X ³² , R)=(—CH, S, —CH ₂ CH ₃ )
Compound (a2-1-2): (X ³¹ , X ³² , R) = (-CH, S, H)
Compound (a2-1-3): (X ³¹ , X ³² , R)=(—CH, O, —CH ₂ CH ₃ )
Compound (a2-1-4): (X ³¹ , X ³² , R) = (-CH, O, H)

A method for synthesizing a compound, wherein X ³¹ , X ³² , (X ³³ ) and R in the starting material (a2-1) are as follows:
Compound (a2-1-5): (X ³¹ , X ³² , R)=(—CH, —NH, —CH ₂ CH ₃ )
Compound (a2-1-6): (X ³¹ , X ³² , R)=(—CH, —NH, H)
Compound (a2-1-7): (X ³¹ , X ³² , X ³³ , R)=(—CH, —NH, —NH, —CH ₂ CH ₃ )
Compound (a2-1-8): (X ³¹ , X ³² , X ³³ , R)=(—CH, —NH, —NH, H)

A method for synthesizing a compound, wherein X ³¹ , X ³² and R in the starting material (a2-1) are as follows:
Compound (a2-1-9): (X ³¹ , X ³² , R)=(N, O, —CH ₂ CH ₃ )
Compound (a2-1-10): (X ³¹ , X ³² , R)=(N, O, H)

A method for synthesizing a compound, wherein X ³¹ , X ³² and R in the starting material (a2-1) are as follows:
Compound (a2-1-11): (X ³¹ , X ³² , R)=(N, —NH, —CH ₂ CH ₃ )
Compound (a2-1-12): (X ³¹ , X ³² , R)=(N, —NH, H)

A method for synthesizing a compound, wherein X ³¹ , X ³² and R in the starting material (a2-1) are as follows:
Compound (a2-1-13): (X ³¹ , X ³² , R)=(N, S, —CH ₂ CH ₃ )
Compound (a2-1-14): (X ³¹ , X ³² , R) = (N, S, H)

<Squarylium dye (IV)>

[The symbols in the above formula are as follows.
R ¹⁴ and R ²⁴ each independently may have a substituent and may contain an unsaturated bond between carbon atoms, a hetero atom, an alicyclic ring or an aromatic ring and has 1 to 20 carbon atoms. is an alkyl group.
R ³⁴ is an organic group R ^34A not essentially having an unsaturated bond or an organic group R ^34B essentially having an unsaturated bond.
^X41 is ^CR43 or N;
X ⁴² is S, NR ⁵³ , or O;
X ⁴³ is S, NR ⁶³ , or O;
R ⁴³ is a hydrogen atom, a halogen atom, a sulfo group, a hydroxyl group, a cyano group, a nitro group, a carbonyl structure-containing monovalent organic group, a phosphate group, a silyl group, a thiol group, a sulfide group, an amide structure-containing monovalent organic group, a sulfone amide group, urea group, urethane structure-containing monovalent organic group, optionally substituted C1-C9 alkyl group, optionally substituted C2-C9 alkenyl group, substituent an alkynyl group having 2 to 9 carbon atoms which may have a substituent, an aryl group having 6 to 9 carbon atoms which may have a substituent, a heteroaryl group having 3 to 9 carbon atoms which may have a substituent, an optionally substituted alkoxy group having 1 to 9 carbon atoms, an optionally substituted acyloxy group having 2 to 9 carbon atoms, or —N(R ^43g ) ₂ (R ^43g is a hydrogen atom or It is an optionally substituted alkyl group having 1 to 4 carbon atoms.).
R ⁴⁴ , R ⁵⁴ , R ⁶⁴ and R ⁷⁴ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, or a monovalent organic group having 1 to 9 carbon atoms.
R ¹⁴ may be combined with R ²⁴ , R ⁵⁴ or R ⁷⁴ to form a 3-6 membered ring.
R ²⁴ may be combined with R ¹⁴ , R ⁵⁴ or R ⁷⁴ to form a 3-6 membered ring. ]

The carbon number of R ¹⁴ includes 1-20. The number of carbon atoms in R ¹⁴ is preferably 2 to 20, more preferably 2 to 16, and even more preferably 2 to 12 when it is linear. The number of carbon atoms in R ¹⁴ is preferably 3 to 20, more preferably 3 to 16, and even more preferably 3 to 12 in the case of a branched chain.
The carbon number of R ²⁴ includes 1-20. The number of carbon atoms in R ²⁴ is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4 when linear, from the viewpoint of the degree of orientation. The number of carbon atoms in R ²⁴ is preferably 3 to 10, more preferably 3 to 6, in the case of a branched chain.

Substituents for R ¹⁴ and R ²⁴ include the same substituents for R ¹³ and R ²³ in squarylium dye (III).

When R ¹⁴ and R ²⁴ contain an alicyclic or aromatic ring in the main chain or side chain, the alicyclic ring preferably has 3 to 10 carbon atoms. The number of carbon atoms in the aromatic ring is preferably 4-14.

When R ¹⁴ and R ²⁴ have a substituent, and when the main chain or side chain contains an alicyclic ring or an aromatic ring, the number of carbon atoms of the substituent, alicyclic ring and aromatic ring is included in the number of carbon atoms.

R ¹⁴ and R ²⁴ may be the same or different. From the viewpoint of the degree of orientation, it is preferred that R ¹⁴ and R ²⁴ are different when chain-like.

From the viewpoint of orientation, R ¹⁴ and R ²⁴ are preferably linear.

More preferably, R ¹⁴ and R ²⁴ are groups selected from groups (1b) to (5b) and groups (1c) to (2c) for R ¹³ and R ²³ in the above squarylium dye (III).

Further, when R ¹⁴ and R ²⁴ are linked to each other to form a heterocyclic ring together with a nitrogen atom, the divalent group —Q ⁴ — to which R ¹⁴ and R ²⁴ are attached is the above-mentioned squarylium dye (III). Groups similar to the divalent group -Q ³ - are preferred.

R ³⁴ is an organic group R ^34A not essentially having an unsaturated bond or an organic group R ^34B essentially having an unsaturated bond.
The organic group R ^34A which does not necessarily have an unsaturated bond is a hydrogen atom, a halogen atom, a hydroxyl group, or an alkyl group which may have a substituent and which may contain an unsaturated bond or an oxygen atom between carbon-carbon atoms. , an alkoxy group, an aryl group or an araryl group.
The organic group R ^34B essentially having an unsaturated bond is an optionally substituted alkenyl group having 2 or more carbon atoms, an optionally substituted alkynyl group having 2 or more carbon atoms, and a substituted imino group having 1 or more carbon atoms, cyano group, organic group having 1 or more carbon atoms and optionally having a carbonyl structure and optionally having a substituent, aryl group having 6 to 9 carbon atoms and optionally having a substituent , or an optionally substituted heteroaryl group having 3 to 9 carbon atoms.

Examples of the substituent for R ^34A include the same substituents for R ^33A in the above-described squarylium dye (III).

When R ^34A is an alkyl group or an alkoxy group, the number of carbon atoms is preferably 1-8, more preferably 1-6, even more preferably 1-3. When R ^33A is an aryl group, it preferably has 6 to 9 carbon atoms. When R ^34A is an araryl group, it preferably has 7 to 9 carbon atoms.
When R ^34A has a substituent, the carbon number of the substituent is included in the carbon number of R ^34A .

R ^34A is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, particularly preferably a hydrogen atom, from the viewpoint of light stability and orientation.

Examples of the substituent for the organic group R ^34B essentially having an unsaturated bond include the same substituents for R ^33B in the above-mentioned squarylium dye (III).
When R ^34B has a substituent, the carbon number of the substituent is included in the carbon number of R ^34B .

When R ^34B is an alkenyl group, it has 2 or more carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, still more preferably 2 to 4 carbon atoms.
As the alkenyl group, a group represented by the above formula (3-1) is preferred, like R ^33B in the above squarylium dye (III).

When R ^34B is an alkynyl group, it has 2 or more carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, still more preferably 2 to 4 carbon atoms.
The alkynyl group is preferably a group represented by the above formula (3-2), like R ^33B in the above squarylium dye (III).

When R ^34B is an imino group, it has 1 or more carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms.
The imino group is preferably a group represented by the above formula (3-3), like R ^33B in the above squarylium dye (III).

When R ^34B is a cyano group, it is a group represented by the above formula (3-4), like R ^33B in the above squarylium dye (III).

When R ^34B is an organic group containing a carbonyl structure and having 1 or more carbon atoms and optionally having a substituent, the number of carbon atoms is 1 or more, preferably 1 to 8, more preferably 1 to 6, More preferably 1-4.
Such an organic group is preferably a group represented by the above formula (3-5), like R ^33B in the above squarylium dye (III).

When R ^34B is an aryl group, it has 6-9 carbon atoms.
The aryl group is preferably a group represented by the above formula (3-6), like R ^33B in the above squarylium dye (III).

When R ^34B is a heteroaryl group, it has 3 to 9 carbon atoms.
The heteroaryl group is preferably a group represented by any one of the above formulas (3-7) to (3-9), like R ^33B in the above squarylium dye (III).

R ⁴⁴ , R ⁵⁴ , R ⁶⁴ and R ⁷⁴ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, or a monovalent organic group having 1 to 9 carbon atoms.

A halogen atom includes a chlorine atom, a fluorine atom, and an iodine atom.
Examples of monovalent organic groups include alkyl groups, alkoxy groups, acyloxy groups, araryl groups, amino groups, alkenyl groups, alkynyl groups, imino groups, cyano groups, carbonyl groups, aryl groups and heteroaryl groups.

In formula (IV), X ⁴¹ is CR ⁴³ or N. X ⁴² is S, NR ⁵³ , or O; X ⁴³ is S, NR ⁶³ , or O; R ⁴³ , R ⁵³ and R ⁶³ are the same as R ⁴³ , R ⁵³ and R ⁶³ in the above squarylium dye (III) including definitions and preferred embodiments.

More specific examples of compound (IV) include the compounds shown in the table below. In addition, in the compounds shown in the following tables, the symbols on the left and right sides of the squarylium skeleton have the same meaning.

Compound (IV) is a cup of 4-aminobenzeneboronic acid in which R ¹⁴ and R ²⁴ are bonded to the amino group, and a condensed heterocyclic compound in which a halogen atom is bonded to the carbon atom between X ⁴¹ and X ⁴² . It can be produced by linking by ring reaction and then reacting with squaric acid.

<Squarylium dye (V)>

[The symbols in the above formula are as follows.
R ¹⁵ and R ²⁵ each independently may have a substituent, an unsaturated bond between carbon atoms, an alkyl group having 1 to 20 carbon atoms which may contain a hetero atom, or an alkyl group having 4 to 4 carbon atoms 20 araryl groups.
R ³⁵ , R ⁴⁵ , R ⁵⁵ and R ⁶⁵ each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an optionally substituted alkyl group having 1 to 9 carbon atoms, an optionally substituted It is an aryl group having 4 to 9 carbon atoms or an araryl group having 5 to 9 carbon atoms which may have a substituent.
R ³⁵ and R ⁴⁵ , R ⁴⁵ and R ⁵⁵ , and R ⁵⁵ and R ⁶⁵ may be linked to each other to form a monocyclic ring or a polycyclic ring in which 2 to 4 rings are condensed.
R ¹⁵ and R ²⁵ may be linked together to form a 4- to 10-membered heterocyclic ring with the nitrogen atom. ]

R ³⁵ , R ⁴⁵ , R ⁵⁵ and R ⁶⁵ each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an optionally substituted alkyl group having 1 to 9 carbon atoms, an optionally substituted It is an aryl group having 4 to 9 carbon atoms or an araryl group having 5 to 9 carbon atoms which may have a substituent.

In R ³⁵ , R ⁴⁵ , R ⁵⁵ and R ⁶⁵ , the alkyl group, aryl group or araryl group may have a substituent.
Alkyl, aryl or araryl groups may also contain unsaturated bonds, oxygen atoms, ester bonds, amide bonds or thioamide bonds between carbon-carbon atoms.
Furthermore, the alkyl group, aryl group, or araryl group may have an oxygen atom, an ester bond, an amide bond, or a thioamide bond at the terminal bound to the thiophene ring.

Substituents for R ³⁵ , R ⁴⁵ , R ⁵⁵ and R ⁶⁵ include halogen atom, hydroxyl group, carboxy group, sulfo group, cyano group, amino group, N-substituted amino group, nitro group, alkoxycarbonyl group, carbamoyl group, Examples include N-substituted carbamoyl groups, imide groups, and alkoxy groups having 1 to 8 carbon atoms. When R ³⁵ , R ⁴⁵ , R ⁵⁵ and R ⁶⁵ are an aryl group or an araryl group, the substituent is a hydrogen atom bonded to an aromatic ring or a group that substitutes a hydrogen atom of an alkyl group possessed by these, and the above substituent contains an aryl group in addition to

When R ³⁵ , R ⁴⁵ , R ⁵⁵ and R ⁶⁵ are alkyl groups, the number of carbon atoms is 1-8, preferably 1-4, more preferably 1-2.
When R ³⁵ , R ⁴⁵ , R ⁵⁵ and R ⁶⁵ are aryl groups, they have 4 to 9 carbon atoms, preferably 4 to 6 carbon atoms.
When R ³⁵ , R ⁴⁵ , R ⁵⁵ and R ⁶⁵ are araryl groups, they have 5 to 9 carbon atoms, preferably 5 to 7 carbon atoms.

When R ³⁵ , R ⁴⁵ , R ⁵⁵ and R ⁶⁵ have a substituent, the number of carbon atoms mentioned above includes the number of carbon atoms of the substituent.

R ³⁵ and R ⁴⁵ , R ⁴⁵ and R ⁵⁵ , and R ⁵⁵ and R ⁶⁵ may be linked to each other to form a monocyclic ring or a polycyclic ring in which 2 to 4 rings are condensed, in which case A hydrogen atom bonded to the ring may be substituted with a substituent.

The ring formed by connecting R ³⁵ and R ⁴⁵ and R ⁵⁵ and R ⁶⁵ may be an alicyclic ring or an aromatic ring, and may be a hydrocarbon ring or a heterocyclic ring. . An aromatic ring is preferred. A monocyclic ring includes a benzene ring, and a polycyclic ring includes a naphthalene ring, anthracene ring, phenanthrene ring, tetracene ring, chrysene ring and the like.

When R ⁴⁵ and R ⁵⁵ are linked, the dye (V) includes a structure in which a ring is formed between two thiophene rings and at least three rings are condensed.

A hydrogen atom bonded to a ring formed by connecting R ³⁵ and R ⁴⁵ , R ⁴⁵ and R ⁵⁵ , and R ⁵⁵ and R ⁶⁵ may be substituted with a substituent.
Substituents in these connecting rings include the same substituents as those in R ³⁵ , R ⁴⁵ , R ⁵⁵ and R ⁶⁵ , and optionally substituted phenyl groups.

R ¹⁵ and R ²⁵ are each independently an alkyl group having 1 to 20 carbon atoms or an araryl group having 4 to 20 carbon atoms.

R ¹⁵ and R ²⁵ may have substituents and may contain unsaturated bonds and heteroatoms between carbon atoms.
Substituents for R ¹⁵ and R ²⁵ include halogen atom, hydroxyl group, carboxy group, sulfo group, cyano group, amino group, N-substituted amino group, nitro group, alkoxycarbonyl group, carbamoyl group, N-substituted carbamoyl group, imide groups, and alkoxy groups having 1 to 19 carbon atoms.
In addition, when R ¹ and R ² have a substituent, the number of carbon atoms of the substituent is included in the number of carbon atoms of R ¹ and R ² .

Substituents for R ¹⁵ and R ²⁵ further include cyclic alkyl or aryl groups. The aryl group is preferably a phenyl group optionally having 1 to 5 substituents or a naphthyl group optionally having 1 to 7 substituents. Substituents which may substitute the hydrogen atoms of the phenyl group and naphthyl group include an alkyl group having 1 to 12 carbon atoms which may contain an unsaturated bond or an oxygen atom between carbon atoms, an alkoxy group, or an alkyl An amino group (wherein the alkyl group has 1 to 12 carbon atoms) can be mentioned. Phenyl and naphthyl groups are preferably unsubstituted or substituted with 1 to 3 hydrogen atoms, and preferred substituents include methyl, t-butyl, dimethylamino and methoxy groups.

When R ¹⁵ and R ²⁵ contain an alicyclic ring or an aromatic ring in the main chain or side chain, the alicyclic ring preferably has 3 to 10 carbon atoms. The number of carbon atoms in the aromatic ring is preferably 4-14.

The substituents on R ¹⁵ and R ²⁵ may further be polymerizable groups for copolymerization with polymerizable liquid crystal compounds.

When R ¹⁵ and R ²⁵ are alkyl groups, from the viewpoint of improving visible light transmittance and dichroic ratio, a linear or branched chain having 1 to 20 carbon atoms which may contain a heteroatom between carbon atoms. A linear or cyclic alkyl group is preferred.
The number of carbon atoms in R ¹⁵ is preferably 2 to 20, more preferably 2 to 16, and even more preferably 2 to 12 when it is linear. In the case of a branched chain, R ¹⁵ preferably has 3 to 20 carbon atoms, more preferably 3 to 16 carbon atoms, and still more preferably 3 to 12 carbon atoms. Furthermore, the number of carbon atoms in R ¹⁵ is preferably 5 to 10 when it is cyclic.
The number of carbon atoms in R ²⁵ is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4 when linear, from the viewpoint of the degree of orientation. The number of carbon atoms in R ²⁵ is preferably 3 to 10, more preferably 3 to 6, in the case of a branched chain. Furthermore, the carbon number of R ²⁵ is preferably 3 to 7 in the case of a cyclic ring.
When R ¹⁵ and R ²⁵ have a substituent, the above carbon number includes the carbon number of the substituent.

R ¹⁵ and R ²⁵ may be the same or different. From the viewpoint of the degree of orientation, it is preferred that R ¹⁵ and R ²⁵ are different when chain-like.

R ¹⁵ is more preferably, for example, a group selected from groups (1a) to (16a), and particularly preferably groups (6a) and (16a) from the viewpoint of the degree of orientation.
R ²⁵ is preferably a linear alkyl group having 1 to 4 carbon atoms, more preferably a methyl group or an ethyl group, from the viewpoint of orientation.

R ¹⁵ and R ²⁵ may be linked to each other to form a 4- to 10-membered heterocyclic ring together with the nitrogen atom. is particularly preferably 4 to 6. In such a heterocyclic ring, one of the hydrogen atoms bonded to the carbon atom farthest from the nitrogen atom may have an unsaturated bond or heteroatom between carbon atoms having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, and further Preferably, it may be substituted with 3 to 8 alkyl groups. The alkyl group may be branched, straight-chain, or cyclic, but a straight-chain is preferable from the viewpoint that the squarylium dye readily exhibits dichroism. Also, some or all of the hydrogen atoms in the heterocyclic ring may be substituted with halogen atoms, in which case some or all of the hydrogen atoms bonded to carbon atoms not adjacent to the nitrogen atom are substituted with halogen atoms. preferably.

When the divalent group to which R ¹⁵ and R ²⁵ are bonded is represented by -Q ⁵ -, specific examples of -Q ⁵ - include the following groups (11) to (15).

—(CH ₂ ) ₄ — (11)
—(CH ₂ ) ₅ — (12)
—C(CH ₃ ) ₂ (CH ₂ ) ₂ C(CH ₃ ) ₂ — (13)
—C(CH ₃ ) ₂ (CH ₂ ) ₃ C(CH ₃ ) ₂ — (14)
—CH ₂ —CH(nC ₈ H ₁₇ )—(CH ₂ ) ₂ — (15)

As the squarylium compound (V), for example, a compound represented by the following formula (V-1) or a compound represented by the following formula (V-2) is preferable. The squarylium compound (V-1) is a squarylium compound (V) in which R ⁴⁵ and R ⁵⁵ are linked to form a cyclopentadithiophene ring. The squarylium compound (V-2) is a compound containing a structure in which R ⁴⁵ and R ⁵⁵ are not linked but two thiophene rings are linked in the squarylium compound (V).

The definitions of R ¹⁵ , R ²⁵ , R ³⁵ and R ⁶⁵ are the same as the definitions of R ¹⁵ , R ²⁵ , R ³⁵ and R ⁶⁵ in formula (V), including preferred embodiments.
The definitions of R ^45b and R ^55b are the same as those of R ⁴⁵ and R ⁵⁵ in Formula (V), including preferred embodiments, except that they are not linked to form a ring.

R ^45a and R ^55a are straight chain having 1 to 9 carbon atoms which may contain an oxygen atom between hydrogen atoms or carbon atoms, from the viewpoint of visible light transmittance, light resistance and dichroic ratio improvement. , branched or cyclic alkyl groups are preferred. The number of carbon atoms in the alkyl group is preferably 1 to 9, more preferably 1 to 4, in the case of a straight chain. In the case of a branched chain, 3 to 9 are preferred, and in the case of a cyclic chain, 5 to 9 are more preferred. R ^45a and R ^55a are preferably, for example, methyl group, ethyl group, phenyl group and the like.

R ^45a and R ^55a are preferably a phenyl group optionally having a substituent or a cyclic alkyl group having 5 to 9 carbon atoms from the viewpoint of heat resistance, light resistance and control of NIR absorption wavelength. Substituents for the phenyl group include an alkyl group having 1 to 3 carbon atoms which may contain an unsaturated bond or an oxygen atom between carbon atoms, an alkoxy group, or an alkylamino group (wherein the alkyl group has 1 to 3 carbon atoms). 3), and particularly preferred are a methyl group, a dimethylamino group, a methoxy group, and the like. The phenyl group is preferably unsubstituted or substituted with 1 to 3 hydrogen atoms.

Specific examples of the phenyl group which may have a substituent include groups (P1) to (P6).

More specific examples of compound (V-1) include the compounds shown in the table below. In addition, in the compounds shown in the following tables, the symbols on the left and right sides of the squarylium skeleton have the same meaning.

Among these, compounds (V-1-51), (V-1-67) and the like are preferable as the compound (V-1) from the viewpoint of improving the dichroic ratio.

Compound (V-2) more specifically includes the compounds shown in the table below. In addition, in the compounds shown in the following tables, the symbols on the left and right sides of the squarylium skeleton have the same meaning.

Among these, compounds (V-2-31), (V-2-41) and the like are preferable as the compound (V-2) from the viewpoint of improving the dichroic ratio.

Compound (V) can be produced by a known method, for example, by the method described in International Publication No. 2019/230660.

<Squarylium dye (VI)>

[The symbols in the above formula are as follows.
R ¹⁶ and R ²⁶ each independently may have a substituent and may contain an unsaturated bond between carbon atoms, a hetero atom, an alicyclic ring or an aromatic ring and has 1 to 20 carbon atoms. is an alkyl group.
R ³⁶ is a monovalent organic group having 9 or less carbon atoms containing an atom having a lone pair of electrons.
R ⁴⁶ is a hydrogen atom or an alkyl group having 1 to 9 carbon atoms.
R ⁵⁶ is a hydrogen atom or an alkyl group having 1 to 9 carbon atoms.
X ⁶¹ is C=O, C ₌ S, or SO2.
R ¹⁶ and R ²⁶ , R ¹⁶ and R ⁴⁶ , R ³⁶ and R ⁴⁶ may be linked together to form a 3- to 6-membered ring. ]

Substituents for R ¹⁶ and R ²⁶ include halogen atoms, hydroxyl groups, carboxy groups, sulfo groups, cyano groups, amino groups, N-substituted amino groups, nitro groups, alkoxycarbonyl groups, carbamoyl groups, N-substituted carbamoyl groups, An imide group and an alkoxy group having 1 to 19 carbon atoms can be mentioned.

Substituents for R ¹⁶ and R ²⁶ further include cyclic alkyl groups or aryl groups. As the aryl group, a phenyl group which may have a substituent or a naphthyl group which may have a substituent is preferable. Substituents which may substitute the hydrogen atoms of the phenyl group and naphthyl group include an alkyl group having 1 to 9 carbon atoms which may contain an unsaturated bond or an oxygen atom between carbon atoms, an alkoxy group, or an alkyl An amino group (wherein the alkyl group has 1 to 9 carbon atoms) can be mentioned. Phenyl and naphthyl groups are preferably unsubstituted or substituted with 1 to 3 hydrogen atoms, and preferred substituents include methyl, t-butyl, dimethylamino and methoxy groups.

The substituents for R ¹⁶ and R ²⁶ may further be polymerizable groups for copolymerization with polymerizable liquid crystal compounds.

When R ¹⁶ and R ²⁶ contain an alicyclic or aromatic ring in the main chain or side chain, it is preferable in terms of heat resistance and control of NIR absorption wavelength. When R ¹⁶ and R ²⁶ do not have an alicyclic ring or an aromatic ring in the main chain or side chain, it is preferable from the viewpoint of light resistance, ease of production, and improvement in dichroic ratio. The number of carbon atoms in the alicyclic ring is preferably 3-10. The number of carbon atoms in the aromatic ring is preferably 4-14.

The carbon number of R ¹⁶ includes 1-20. The number of carbon atoms in R ¹⁶ is preferably 2 to 20, more preferably 2 to 16, even more preferably 2 to 12, in the case of a linear chain. The number of carbon atoms in R ¹⁶ is preferably 3 to 20, more preferably 3 to 16, even more preferably 3 to 12 in the case of a branched chain.
The carbon number of R ²⁶ includes 1-20. The number of carbon atoms in R ²⁶ is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 4 when linear, from the viewpoint of the degree of orientation. The number of carbon atoms in R ²⁶ is preferably 3 to 10, more preferably 3 to 6, in the case of a branched chain.

When R ¹⁶ and R ²⁶ have a substituent, and when the main chain or side chain contains an alicyclic ring or an aromatic ring, the number of carbon atoms of the substituent, alicyclic ring and aromatic ring is included in the number of carbon atoms.

R ¹⁶ and R ²⁶ may be the same or different. From the viewpoint of the degree of orientation, it is preferable that R ¹³ and R ²³ are different when chain-like. From the viewpoint of the degree of orientation, R ¹⁶ and R ²⁶ are preferably linear rather than branched.

When R ¹⁶ and R ²⁶ are branched, the number of branches is not particularly limited. The number of branches is preferably 1-5, more preferably 1-3. From the viewpoints of both solubility in liquid crystals and solvents and ease of production, the branching position is preferably the β-position. In addition, one carbon atom may be branched into two or three.

More preferably, R ¹⁶ and R ²⁶ are groups selected from groups (1b) to (5b), (1c) and (2c) described as more preferred embodiments of R ¹³ and R ²³ in the squarylium dye (III). .
—CH(C _n H _2n+1 ) ₂ (1b)
-C(C _n H _2n+1 ) ₃ (1c)
—CH ₂ —CH(C _n H _2n+1 ) ₂ (2b)
—CH ₂ —C(C _n H _2n+1 ) ₃ (2c)
—(CH ₂ ) ₂ —CH(C _n H _2n+1 ) ₂ (3b)
—(CH ₂ ) ₃ —CH(C _n H _2n+1 ) ₂ (4b)
—(CH ₂ ) _m —CH ₃ (5b)

However, in formulas (1b) to (4b), (1c) and (2c), n is an integer of 1 to 10, preferably 2 to 8, more preferably 2 to 4. However, the number of carbon atoms in groups (1b) to (4b) and groups (1c) to (2c) should be within the range of 1-20. Two C _n H 2n+1 in formulas (1b) to (4b), (1c), and (2c) and three C _n H _{2n +1} in formulas (1c) to (2c) may each be a straight chain. They may be branched and may be the same or different. In formula (5b), m is an integer of 0 to 19, preferably 0 to 15, more preferably 0 to 11. In addition, groups (1b)-(5b), (1c), (2c) may have heteroatoms between carbon-carbon atoms.

R ³⁶ is a monovalent organic group having 9 or less carbon atoms containing an atom having a lone pair of electrons. The bonding of the group with the lone pair to the carbon atom closest to the squarylium skeleton increases the electron density of the unsaturated carbocycle, and the atom with the lone pair in the formation of the dye (reaction with squaric acid) becomes necessary. From this point of view, the atom having a lone pair of electrons in R ³⁶ is preferably directly bonded to the carbon atom of the unsaturated carbocyclic ring to which R ³⁶ is bonded.
Preferably, the atom with the lone pair of electrons is N, S or O.

R ³⁶ is preferably NH—Y ^36a —R ^36a , SH, or OH.
In NH-Y ^36a -R ^36a , Y ^36a is a single bond or a divalent organic group having 0 to 3 carbon atoms, preferably -CO-, -COO-, -CONH- or -SO ₂ -.
R ³⁶ is preferably NH--R ^36a , NH--CO--R ^36a , NH--COO--R ^36a , NH--CONH--R ^36a , NH--SO ₂ --R ^36a , SH or OH.

In NH-Y ^36a -R ^36a , R ^36a may have a substituent, may contain an unsaturated bond between carbon atoms, an oxygen atom, an alicyclic ring or an aromatic ring, and may have 1 to 9 carbon atoms. is an alkyl group. The upper limit of the total carbon number of Y ^36a and R ^36a is 9.

The number of carbon atoms in R ^36a is preferably 1 to 9, more preferably 1 to 4, and particularly preferably 1 to 2 when it is linear, and preferably 3 to 9 when it is branched, and 3 to 4 is particularly preferred.

Substituents for R ^36a include the same groups as the substituents for R ¹⁶ and R ²⁶ .
When R ^36a has a substituent and when the main chain or side chain contains an alicyclic ring or an aromatic ring, the number of carbon atoms in the substituent, the alicyclic ring and the aromatic ring are included in the above number of carbon atoms.

From the viewpoint of improving the dichroic ratio, R ^36a is preferably linear.

R ^36a is more preferably a group selected from groups (11b) to (15b), (11c) and (12c).
—CH(C _n H _2n+1 ) ₂ (11b)
-C(C _l H _2l+1 ) ₃ (11c)
—CH ₂ —CH(C _n H _2n+1 ) ₂ (12b)
—CH ₂ —C(C _l H _2l+1 ) ₃ (12c)
—(CH ₂ ) ₂ —CH(C _n H _2n+1 ) ₂ (13b)
—(CH ₂ ) ₃ —CH(C _n H _2n+1 ) ₂ (14b)
—(CH ₂ ) _m —CH ₃ (15b)

However, in formulas (11b) to (14b), n is an integer of 1 to 3, preferably 2 to 3. In formulas (11c) and (12c), l is an integer of 1-2. Two C _n H _2n+1 or three C _l H _2l+1 in formulas (11b)-(14b), (11c), (12c) may be linear or branched and may be identical. may be different. In formula (15b), m is an integer of 0 to 8, preferably 0 to 8, more preferably 0 to 3, and even more preferably 0 to 1. Furthermore, groups (11b)-(15b), (11c) and (12c) may have an oxygen atom between carbon atoms.

R ⁴⁶ is a hydrogen atom or an alkyl group having 1 to 9 carbon atoms.

The number of carbon atoms in the alkyl group is preferably 1-8, more preferably 1-4.
The alkyl group may be linear or branched, but is preferably linear from the viewpoint of improving the dichroic ratio.

When R ⁴⁶ is an alkyl group having 1 to 9 carbon atoms, a group selected from groups (11b) to (15b), (11c) and (12c) described as preferred embodiments for R ^36a is more preferred.

From the viewpoint of steric hindrance, R ⁴⁶ is preferably a hydrogen atom.

R ⁵⁶ is a hydrogen atom or an alkyl group having 1 to 9 carbon atoms.
From the viewpoint of steric hindrance, R ⁵⁶ is preferably a hydrogen atom.

R ¹⁶ and R ²⁶ , R ¹⁶ and R ⁴⁶ , R ³⁶ and R ⁴⁶ may be linked together to form a ring.
As the ring, R ¹⁶ and R ²⁶ , R ¹⁶ and R ⁴⁶ are preferably 3- to 6-membered alicyclic rings, and R ³⁶ and R ⁴⁶ are preferably 3- to 6-membered alicyclic or aromatic rings. Moreover, the ring may have a substituent. Substituents include the same groups as the substituents for R ¹⁶ and R ²⁶ .

X ⁶¹ is C=O, C ₌ S, or SO2.

As the squarylium compound (VI), a squarylium compound represented by the following formula (VI-1) is preferable.

R ¹⁶ to R ⁴⁶ are the same as R ¹⁶ to R ⁴⁶ in Formula (VI) including preferred embodiments.

The squarylium compound (VI) includes the following squarylium compound (VI-11) in which R ³⁶ is NH—CO—R ^36a , and the following squarylium compound (VI-12) in which R ³⁶ is NH—SO ₂ —R ^36a . , the squarylium compound (VI-13) below, wherein R ³⁶ is NH-CONH-R ^36a , the squarylium compound (VI-14) below, wherein R ³⁶ is NH-COO-R ^36a , R ³⁶ is OH, The following squarylium compound (VI-15) is preferred.

As the squarylium compounds (VI-11) to (VI-15), more specifically, R ¹⁶ , R ²⁶ , R ^36a , and R ⁴⁶ are compounds shown in the following table (in the table, the squarylium compounds (VI-11) to (VI-15) are also shown together.). In the table, R ¹⁶ , R ²⁶ , R ^36a and R ⁴⁶ represent the symbols of the formulas when they are the groups having the formulas. In all the compounds shown in the table, R ¹⁶ , R ²⁶ , R ^36a and R ⁴⁶ are all the same on the left and right sides of the formula.

<Method for producing compound (VI)>
The method for producing the squarylium compound (VI) will be described using the method for producing the squarylium compound (VI-11), but the method for producing the squarylium compound (VI) is not limited thereto.
Scheme (F-A11) shows a method for obtaining squarylium compound (VI-11).

_{( 1} ) _{Compound ( pA11} -2) is obtained.
(2) A compound (pA11-3) is obtained by a nitration reaction.
(3) A compound (pA11-4) is obtained by deprotecting the amino group.
(4) N alkylation (S _N 2 reaction using alkyl halide and base, or reductive amination reaction using aldehyde and reducing agent) to give compound (pA11-5).
(5) Reduction of the nitro group gives compound (pA11-6).
(6) Compound (pA11-7) is obtained by reacting compound (pA11-6) with an alkanoyl chloride (R ^36a -C(=O)-Cl).
(7) A compound (pA11-8) is obtained by deprotecting the methoxy group.
(8) Compound (VI-11) is obtained by reacting compound (pA11-8) with squaric acid.

The squarylium compound (VI-12) can be produced by changing the alkanoyl chloride (R ^36a -C(=O)-Cl) in step (6) above to R ^36a SO ₂ Cl.
The squarylium compound (VI-13) can be produced by reacting R ^36a NH ₂ after reacting carbonyldiimidazole in step (6) above.
The squarylium compound (VI-14) can be produced by changing the alkanoyl chloride (R ^36a -C(=O)-Cl) in step (6) above to R ^36a OC(=O)-Cl.

In the composition of the present invention, the content of the dichroic dye is preferably 0.02 mmol or more with respect to 100 parts by mass of the polymerizable liquid crystal compound, from the viewpoint of ensuring sufficient absorbance for polarized light parallel to the absorption axis. , More preferably 0.05 mmol or more, from the viewpoint of ensuring the transmittance for polarized light perpendicular to the absorption axis and maintaining the solubility in the polymerizable liquid crystal compound, preferably 100 parts by mass of the polymerizable liquid crystal compound 10 mmol or less, more preferably 7 mmol or less. Two or more dichroic dyes may be used in combination, in which case the total content should be within the above range.

<Polymerizable liquid crystal compound>
The polymerizable liquid crystal composition of the present invention contains a polymerizable liquid crystal compound. A polymerizable liquid crystal compound is a compound having a polymerizable group and exhibiting liquid crystallinity. A polymerizable group means a group involved in a polymerization reaction of a polymerizable liquid crystal compound. By having both properties as a polymerizable monomer and properties as a liquid crystal, an optically anisotropic material in which the orientation of the liquid crystal compound is fixed can be obtained by polymerizing after aligning the polymerizable liquid crystal compound. Since the optically anisotropic material has optical anisotropy such as refractive index anisotropy derived from the mesogenic skeleton, this property can be used to produce diffraction elements, retardation plates, and the like.

The polymerizable liquid crystal compound in the present invention exhibits a smectic liquid crystal phase. A smectic liquid crystal phase is a liquid crystal in which the long axes of rod-like molecules are arranged in parallel to form layers. The regularity is higher than that of nematic liquid crystals, which have no positional regularity. When the liquid crystal phase exhibited by the polymerizable liquid crystal compound is a smectic liquid crystal phase, an optical element having a high degree of orientational order can be obtained.

The smectic liquid crystal phase includes smectic liquid crystal A phase, smectic liquid crystal B phase, smectic liquid crystal D phase, smectic liquid crystal E phase, smectic liquid crystal F phase, smectic liquid crystal G phase, smectic liquid crystal H phase, smectic liquid crystal I phase, and smectic liquid crystal J phase. and smectic liquid crystal K phase, and those with tilted smectic liquid crystal phase selected from these. Among them, smectic liquid crystal B phase, smectic liquid crystal F phase, smectic liquid crystal I phase, tilted smectic liquid crystal F phase and tilted smectic liquid crystal I phase are preferable, and smectic liquid crystal B phase is more preferable.

The polymerizable liquid crystal compound contains one or more polymerizable groups, and although the polymerizable group is not particularly limited, it is preferably a photopolymerizable group. Examples include CH ₂ ═CH—, CH ₂ ═CCl—, CH ₂ ═C(CH ₃ )—, 4-vinylphenylyl, etc. Suitable examples include acrylates, methacrylates, vinyl ethers, oxetanes, Examples include epoxy or thiolene.

A polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase is described by Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), Japanese Patent No. 4,719,156, etc., or a commercially available product may be used.

The content of the polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase in the composition of the present invention is preferably in the range of 70 to 99.9% by mass, more preferably in the range of 90 to 99.9% by mass, based on the solid content of the composition. is more preferred. Within the above range, the orientation of the liquid crystal compound tends to be high. Here, the solid content refers to the total amount of components of the composition excluding the solvent. A liquid crystal compound may be used independently or may use multiple types together.

<Polymerization initiator>
The polymerizable liquid crystal composition of the invention preferably further contains a polymerization initiator. A polymerization initiator is a compound that initiates polymerization of a polymerizable liquid crystal compound, and generates active radicals and acids by the action of light and/or heat. Among them, a polymerization initiator that generates an active radical or an acid by the action of light (that is, a photopolymerization initiator) is preferable because it is easy to cure while maintaining liquid crystallinity, and photopolymerization that generates radicals by light irradiation. Initiators are more preferred. The light used for photopolymerization is preferably ultraviolet light or visible light.

As the photopolymerization initiator, a photopolymerization initiator appropriately selected from acetophenones, benzophenones, benzoins, benzyls, Michler ketones, benzoin alkyl ethers, benzyldimethylketals, acylphosphine oxides, thioxanthones, and the like. is preferably used. A photoinitiator can be used 1 type or in combination of 2 or more types. Moreover, a commercially available photopolymerization initiator can be used.

Examples of thermal polymerization initiators include azo compounds such as azobisisobutyronitrile; hydrogen peroxide, persulfates, and peroxides such as benzoyl peroxide. Moreover, a commercially available thermal polymerization initiator can be used.

The content of the polymerization initiator in the composition of the present invention is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 7 parts by mass based on 100 parts by mass of the polymerizable liquid crystal compound. Within the above range, the polymerizable liquid crystal compound can be polymerized without disturbing its orientation.

<Antioxidant>
The polymerizable liquid crystal composition of the invention preferably further contains an antioxidant. By including an antioxidant in the composition of the present invention, the polymerization of the polymerizable liquid crystal compound can be controlled, and the stability of the polymerizable liquid crystal composition of the present invention can be improved.

Examples of antioxidants include hindered phenols, hydroquinone, alkoxy group-containing hydroquinone, alkoxy group-containing catechol (eg, butyl catechol, etc.), pyrogallol, 2,2,6,6-tetramethyl-1-piperidinyloxy radical. thiophenols, β-naphthylamines, β-naphthols and the like.

The content of the antioxidant in the composition of the present invention is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 2 parts by mass based on 100 parts by mass of the polymerizable liquid crystal compound. Within the above range, polymerization can be controlled without disturbing the orientation of the polymerizable liquid crystal compound.

<Leveling agent>
The polymerizable liquid crystal composition of the invention may further contain a leveling agent. The leveling agent has the function of adjusting the fluidity of the polymerizable liquid crystal composition and flattening the applied film. When forming a coating film from a polymerizable liquid crystal composition, it is preferable to include a leveling agent because a flat film can be obtained. A surfactant or the like is preferably used as the leveling agent.
The content of the leveling agent in the composition of the present invention is preferably 0.3 parts by mass or more and 5 parts by mass or less, more preferably 0.5 parts by mass or more and 3 parts by mass or less relative to the polymerizable liquid crystal compound. . is. Within the above range, it is easy to obtain a flat coating film.

<Solvent>
The polymerizable liquid crystal composition of the invention may further contain a solvent. When forming a coating film from a polymerizable liquid crystal composition, it is preferable to contain a solvent because a uniform film can be obtained. As the solvent, a solvent capable of dissolving components such as the liquid crystal compound and the dichroic dye and inert to the polymerization reaction of the liquid crystal compound is preferable.

Examples of solvents include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ- ester solvents such as butyrolactone or propylene glycol methyl ether acetate and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; These solvents may be used alone or in combination.

When the composition of the present invention contains a solvent, its content is preferably 50 to 98% by mass based on the total amount of the composition. In other words, it is preferable that the solid content concentration in the composition is 2 to 50% by mass. Within the above range, the thickness of the film obtained from the composition is sufficient to exhibit dichroism, and a uniform film can be obtained during coating, which is preferable.

<Optical anisotropic material>
The optically anisotropic material of the present invention comprises the polymer of the polymerizable liquid crystal composition of the present invention.
The polymerization method is not particularly limited, but it is necessary to polymerize in a state in which the polymerizable liquid crystal composition exhibits a smectic liquid crystal phase and in a state in which the liquid crystal is oriented.
In order to create a state in which the polymerizable liquid crystal composition exhibits a smectic liquid crystal phase, the ambient temperature should be within the temperature range in which the polymerizable liquid crystal compound exhibits a smectic liquid crystal phase, or lower. At this time, after the polymerizable liquid crystal composition is heated to a temperature at which the polymerizable liquid crystal compound exhibits a nematic liquid crystal phase or higher to form a nematic liquid crystal phase, the polymerizable liquid crystal compound exhibits a smectic liquid crystal phase within a temperature range, or A smectic liquid crystal phase is preferably formed by cooling to a temperature below that. Furthermore, when forming a nematic liquid crystal phase, after heating the polymerizable liquid crystal composition to a temperature higher than the temperature at which the polymerizable liquid crystal compound exhibits an isotropic phase to form an isotropic phase, the polymerizable liquid crystal compound forms a nematic liquid crystal phase. A nematic liquid crystal phase may be formed by cooling to within the temperature range or below. These manipulations can create a more uniform orientation.

The nematic liquid crystal phase and smectic liquid crystal phase can be confirmed by, for example, texture observation using a polarizing microscope, X-ray diffraction measurement, or differential scanning calorimetry.

The optically anisotropic material can be formed, for example, by polymerizing a polymerizable liquid crystal composition sandwiched between a pair of substrates whose surfaces have been subjected to alignment treatment.

Examples of the substrate include substrates made of glass or transparent resin. The thickness of the substrate is usually preferably 0.2 to 1.5 mm.

As a method of applying the orientation treatment to the surface of the substrate, for example, an orientation film is formed on the substrate and the orientation treatment is applied to the orientation film. The alignment film may have a function of aligning liquid crystals, and may be organic materials such as polyimide, polyamide, polyvinyl alcohol, polyvinyl cinnamate and polystyrene, or inorganic materials such as SiO ₂ and Al ₂ O ₃ . can be used. Specifically, the orientation treatment can be performed using a rubbing method or the like. For example, by rubbing the surface of the alignment film in one direction with a rubbing cloth such as nylon or rayon, the liquid crystal compound is aligned in that direction. In addition to the rubbing method, the orientation of the liquid crystal compound can be aligned by oblique vapor deposition of SiO ₂ , an ion beam method, a photo-alignment film, or the like.

Next, an optically anisotropic material is formed on the alignment film. Separately from the above substrate (hereinafter referred to as the first substrate), a second substrate having an alignment film formed on its surface is newly prepared. This alignment film may be formed in the same manner as the first substrate. Next, if necessary, the surface of the second substrate on which the alignment film is formed is subjected to mold release treatment. As the mold release agent, for example, a fluorosilane-based agent or a fluorine-containing polymer having a fluorine-containing alicyclic structure can be used. Next, the first substrate is overlaid on the second substrate and temporarily adhered with a space therebetween. At this time, the surface of the second substrate on which the alignment film is formed or the surface subjected to the release treatment and the surface of the first substrate on which the alignment film is formed are directed inward. In addition, an opening is provided through which the polymerizable liquid crystal composition can be filled from the outside. Then, a polymerizable liquid crystal composition is injected between the substrates through this opening. For injection, a vacuum injection method may be used, or a method utilizing capillary action in the atmosphere may be used, and the liquid crystal composition may be melted by heating and injected. After the injection of the polymerizable liquid crystal composition, the ambient temperature is set within or below the temperature range at which the polymerizable liquid crystal compound exhibits a smectic liquid crystal phase, so that the polymerizable liquid crystal composition exhibits a smectic liquid crystal phase. do. At this time, the polymerizable liquid crystal composition is heated to within the temperature range in which the polymerizable liquid crystal compound exhibits a nematic phase or within the temperature range in which it exhibits an isotropic phase, and within the temperature range in which the polymerizable liquid crystal compound exhibits a smectic liquid crystal phase, or It is preferable to make a state exhibiting a smectic liquid crystal phase by cooling to below that temperature. Then, the polymerizable liquid crystal composition is polymerized. If the polymerizable group of the polymerizable liquid crystal composition is a photopolymerizable group, photopolymerization is performed by irradiating light of a predetermined wavelength, and if the polymerizable group is a thermally polymerizable group, heat is applied to perform thermal polymerization. conduct. After that, by removing the temporarily bonded second substrate as necessary, a structure in which an alignment film and an optically anisotropic material are formed between the two substrates or on the first substrate is obtained. be able to. In the embodiment of the present invention, the polymerizable liquid crystal composition is oriented in a direction substantially parallel to the surface of the first substrate, and the optically anisotropic material is obtained with this orientation fixed.

Formation of the optically anisotropic material can also be carried out, for example, as follows.
First, a first substrate having an alignment film formed thereon and a second substrate having a release agent applied to the surface having the alignment film formed thereon, if necessary, are prepared. Next, a photocurable polymerizable liquid crystal composition is dropped onto the alignment film formed on the first substrate. After that, the second substrate is superimposed on the first substrate so that the surface on which the alignment film is formed or the surface on which the release agent is applied faces the polymerizable liquid crystal composition. Next, the polymerizable liquid crystal composition is polymerized in a state in which the polymerizable liquid crystal composition exhibits a smectic liquid crystal phase. After that, if necessary, the second substrate is removed to obtain a structure in which an alignment film and an optically anisotropic material are formed between the two substrates or on the first substrate in the same manner as described above. can be done.

Formation of the optically anisotropic material can also be carried out, for example, as follows.
First, a polymerizable liquid crystal composition is applied to the surface of a substrate that has been subjected to alignment treatment, and the resulting coating film is polymerized in a state in which it is converted into a film having a liquid crystal phase. In this case, the polymerizable liquid crystal composition preferably contains a solvent at the time of coating from the viewpoint of improving the handling of the coating. Further, examples of the coating method on the substrate include spin coating, die coating, dip coating, bar coating, and the like. After application to the substrate, it is preferable to remove volatile components such as solvents by drying from the viewpoint of film-forming properties. In order to convert the coating film into a film in which a smectic liquid crystal phase is formed, the polymerizable liquid crystal composition is heated within a temperature range in which the polymerizable liquid crystal compound exhibits a nematic phase or within a temperature range in which it exhibits an isotropic phase, The polymerizable liquid crystal compound may be cooled to within or below the temperature range in which the smectic liquid crystal phase is exhibited.

<Optical element>
The optically anisotropic material of the present invention can be used as a material for optical elements.
In the present invention, the dichroic dye transmits visible light and absorbs near-infrared light, so the optically anisotropic material of the present invention has both properties of refractive index anisotropy and light absorption anisotropy. Therefore, it functions as a retardation plate in the visible light region and as a polarizer in the near-infrared region.
Examples of optical elements include polarizers, retardation plates, wavefront correction elements, diffraction gratings, and the like. A display member, an imaging member, a sensor, and the like can be produced by using these materials.
Since the optical element using the optically anisotropic material of the present invention has a near-infrared absorption ability, it can be used as a sensor for near-infrared light and infrared light. There is an advantage that stray light is less likely to occur.

The optical element of the present invention can be mounted on various devices described below.

<Imaging device>
An imaging device of the present invention includes, for example, a solid-state imaging device, an imaging lens, and the optical element of the present invention. As a result, a good image with high color reproducibility can be obtained.

<Light wave ranging device>
A light wave distance measuring device of the present invention includes, for example, a laser diode, a scanning unit such as a beam splitter or a MEMS mirror, a photodiode, and the optical element of the present invention. As a result, it is possible to suppress return optical noise to the laser diode and stray light in the light wave rangefinder, improve detection accuracy, and reduce erroneous detection.

<Virtual reality device>
The virtual reality apparatus of the present invention includes, for example, a display unit such as an LCD, OLED, or μLED, a lens unit, an optical element of the present invention between the display unit and the lens unit, and a near-infrared illuminator capable of photographing the user's eyes. and a camera equipped with
The lens unit can include a retardation plate and a reflective polarizer, and the retardation plate of the present invention can be used as the retardation plate.
As an optical element between the display unit and the lens unit, the retardation plate and polarizer of the present invention can be used.
With the above configuration, it is possible to suppress stray near-infrared light in the virtual reality apparatus, improve eye tracking accuracy, and reduce erroneous detection.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples.

The dyes used in each example are as follows.
<Near-infrared absorbing dye>
Compound 1: Pyrrolidone and TMS-Cl are reacted to form N-TMS-pyrrolidone, which is reacted with LDA to react with n-octane iodide, added with water to give 5-octylpyrrolidone, and reduced with _LiAlH4 . , the corresponding amine (3-octylpyrrolidine) was synthesized, and others were synthesized based on WO2017/135359.
Compound 2: Synthesized according to WO2019/230570 except that 3-octylpyrrolidine was used as the amine.
Compound 3: Synthesized based on International Publication No. 2019/230660 except that acetone was used as the ketone and 3-octylpyrrolidine was used as the amine.
Compound 4: Synthesized according to International Publication No. 2019/230660 except that acetone was used as the ketone and pyrrolidine was used as the amine.
<Visible light absorption dye>
Compound 5: A commercially available product (manufactured by Hayashibara Co., Ltd., trade name G-205) was used.
Compound 6: A commercially available product (2,4-Bis[4-(diethylamino)-2-hydroxyphenyl]squaraine manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

The aspect ratio of each dye was calculated by optimizing the structure using B3LYP/6-31G* as a keyword in molecular orbital calculation software Gaussian 16, and loading the optimized structure into simulation software Winmostar.

As the liquid crystal compound, the following polymerizable smectic liquid crystal compound exhibiting a smectic liquid crystal B phase was used. Liquid crystal compounds are disclosed in Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), Japanese Patent No. 4719156 and other known methods.

Irgacure 369E manufactured by BASF was used as a photopolymerization initiator.

As an antioxidant, Irganox 1010 manufactured by BASF was used.

<Production of Polymerizable Liquid Crystal Composition and Evaluation of Dichroic Ratio>
(Example 1)
With respect to 100 parts by mass of the liquid crystal compound, 0.3 mmol of the squarylium dye of compound 1, 0.2 parts by mass of the polymerization initiator, and 0.4 parts by mass of antioxidant are dissolved in dichloromethane, and dried to obtain dichloromethane. was removed to obtain a polymerizable liquid crystal composition of Example 1.
An alignment cell manufactured by EHC Co., Ltd. in which a gap of 5 μm was maintained was heated to 120° C., the resulting polymerizable liquid crystal composition was injected into the cell, heated at 140° C. for 5 minutes, and then cooled to room temperature (25° C. ) to form a smectic B phase.
The composition was polymerized by irradiating UV light with a wavelength of 365 nm under the conditions of 50 mW/cm ² ×30 seconds.
Polarized light parallel to the rubbing direction and polarized light perpendicular to the rubbing direction are irradiated, and the respective absorption spectra (A|| and A⊥) are measured with a visible absorption spectrometer (SolidSpec-3700DUV manufactured by Shimadzu Corporation). was measured.

(Example 2)
A polymerizable liquid crystal composition was prepared, a polymer was obtained, and the dichroic ratio was measured in the same manner as in Example 1 except that compound 2 was used as the squarylium dye.

(Example 3)
A polymerizable liquid crystal composition was prepared and a polymer was obtained in the same manner as in Example 1 except that compound 3 was used as the squarylium dye and the amount of the dye was changed to 1.2 mmol with respect to 100 parts by mass of the polymerizable liquid crystal compound. , the dichroic ratio was measured.

(Example 4)
A polymerizable liquid crystal composition was prepared, a polymer was obtained, and the dichroic ratio was measured in the same manner as in Example 1 except that compound 4 was used as the squarylium dye.

(Example 5)
A polymerizable liquid crystal composition was prepared in the same manner as in Example 1, except that the visible light absorbing dye of compound 5 was used as the dye, and the amount of the dye was changed to 1 mmol with respect to 100 parts by mass of the polymerizable liquid crystal compound, and the polymer was added. obtained and the dichroic ratio was measured.

(Example 6)
A polymerizable liquid crystal composition was prepared, a polymer was obtained, and the dichroic ratio was measured in the same manner as in Example 1, except that the visible light absorbing dye of compound 6 was used as the dye.

The following table shows the dichroic ratio of the polymer obtained from each polymerizable liquid crystal composition and the maximum absorption wavelength of each dye.
Examples 1 to 4 are examples, and examples 5 and 6 are reference examples.

From the above results, all the polymers obtained from the polymerizable liquid crystal compositions of Examples exhibited excellent dichroism.

The polymerizable liquid crystal composition of the present invention is useful as a material for optical elements such as polarizers, retardation plates, wavefront correction elements and diffraction gratings. In addition, the polymer obtained from the polymerizable liquid crystal composition of the present invention has near-infrared absorption ability, and is therefore particularly useful for near-infrared light and infrared light sensors.

Claims (10)

A polymerizable liquid crystal composition comprising a dichroic dye and a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase,
A polymerizable liquid crystal composition, wherein the dichroic dye is a near-infrared absorbing dye having a maximum absorption wavelength in a wavelength region of 700 nm or more. 2. The polymerizable liquid crystal composition according to claim 1, wherein the near-infrared absorbing dye has an aspect ratio of 1.5 or more. 3. The polymerizable liquid crystal composition according to claim 1, wherein said near-infrared absorbing dye is a squarylium dye. 4. The polymerizable liquid crystal composition according to any one of claims 1 to 3, wherein the near-infrared absorbing dye is a compound represented by the following formula (X).

[The symbols in the formula (X) are as follows.
Ar is an aromatic monocyclic, condensed or linked ring having 5 to 14 carbon atoms.
Each of R ¹ and R ² is independently a hydrogen atom or one having 1 to 20 carbon atoms which may have a substituent and may contain an unsaturated bond, hetero atom or ring structure between carbon atoms. indicates a valent hydrocarbon group.
The carbon atoms constituting R ¹ and R ² , or at least one of R ¹ and R ² and Ar may be linked together to form a 3- to 10-membered heterocyclic ring together with the nitrogen atom. ] 5. The polymerizable liquid crystal composition according to claim 4, wherein Ar has one or more substituents selected from halogen atoms, hydroxyl groups, and monovalent organic groups R 1 ^Ar having 1 to 9 carbon atoms. 6. The polymerizable liquid crystal composition according to claim 1, wherein the smectic liquid crystal phase is a smectic liquid crystal B phase, a smectic liquid crystal F phase, or a smectic liquid crystal I phase. 7. The polymerizable liquid crystal composition according to claim 1, which is used for a polarizer. An optically anisotropic material comprising a polymer of the polymerizable liquid crystal composition according to any one of claims 1 to 7. An optical element comprising the optically anisotropic material according to claim 8 . A polarizer comprising the optically anisotropic material according to claim 8 .