JPH0977767A - Chiral photochromic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a chiral photochromic material expressed by a specific formula, capable of carrying out an optical asymmetric induction of a ring closed compound having helicene simulant structure, optically forming an another asymmetric structure of helicene and inducing a high angle of rotation by introducing an asymmetric molecule into a diaryl ester molecule. SOLUTION: This chiral photochromic material is a compound of formula I X is formulas II-IV [(n) is 2-6; R<7> is a (substituted) alkyl or aryl]; YZ is O atom, S atom or a (substituted) NH; R<1> and R<4> are each an alkyl, alkoxy or an alkoxycarbonyl; R<2> , R<3> , R<5> and R<6> are each an alkyl, H or a halogen; at least one of R<1> to R<6> is an asymmetric carbon, R<2> and R<3> and/or R<5> and R<6> are bound each other and form a ring}. E.g. 2-(2-methyl-3-benzothienyl)-(2-1- menthyl-3-benzothienyl)-N-cyanomethylmaleimide, etc. The objective compound can be obtained by condensing a 3-oxamoyl substituted unsaturated heterocyclic compound with an unsaturated heterocycle-3-substituted acetic acid chloride.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photochromic compound which changes optical rotation upon irradiation with light, and is suitable for an optical recording medium, and more particularly to a material for performing nondestructive readout of recording by optical rotation reading.

[0002]

2. Description of the Related Art A photochromic material refers to a material containing molecules or molecular aggregates that reversibly generate two isomers having different states by the action of light. Research and development is being pursued with the aim of applying photochromic materials to optical recording media. The performance required for the recording medium is as follows.

1) Repeated durability 2) Thermal irreversibility 3) Semiconductor laser sensitivity 4) Non-destructive reading function 5) High-speed and high-sensitivity response 6) Thin film forming ability Aiming at molecules having all of these, repeated durability The development of photochromic molecules (diarylethene, fulgide) that possess the properties of heat and are irreversible has been promoted. At present, diarylethene molecules have been obtained that have sufficient cyclic durability, thermal irreversibility, and high-speed and high-sensitivity response (M.Irie, Mol.Cryst.Liq.Cry).
st.227,263 (1993)).

The problem left for the optical recording material using the photochromic material is to achieve the nondestructive read function. Conventional photochromic materials have a drawback that the photoreaction progresses in proportion to the amount of absorbed light, and therefore even if a weak reading light is used, the record disappears when read many times.

[0005]

In order to achieve nondestructive reading, a reaction system having a threshold value in the photoreaction is constructed. The birefringence or the optical rotation that is changed by the photochromic reaction with light having a wavelength that does not induce the photoreaction. Is required to be used.

[0006] One of the methods is to synthesize a photochromic molecule that reacts with two photons. It has been found that a naphthopyran derivative undergoes a two-photon photochromic reaction, and its investigation has begun (M.Uchida, M.Irie; J.
Am. Chem. Soc., 115 (1993) 6442). Hattori et al. Proposed that the birefringence be read out and used as a physical quantity (Y. Hattori, J. Yoshitake, T. Yamanaka; "Che
mistry of Functional Dyes ", Z. Yoshida, T. Kitao ed
s. (1989) 326-329). The above-mentioned two-photon system has a defect that the absorption wavelength is too short, and the birefringence reading is anxious about storage stability.

The present invention relates to a material for optical rotation reading which is one of the methods. In birefringence reading, the orientation of photochromic molecules is essential. A stretched polymer material or liquid crystal is used for orientation,
In either case, when stored for a long time, relaxation occurs and the degree of orientation changes, resulting in loss of recording. On the other hand, in the present invention, since the optical rotation of the molecule itself changes, the problem of storage stability does not occur, and the optical rotation can be read at a wavelength that does not induce a photoreaction. So far, it has been attempted to introduce an asymmetric molecule into azobenzene or spirobenzopyran to change induced circularly polarized light (induced CD) or optical rotation change by a photochromic reaction (M.Go.
oman, A. Koosoy, J. Am. Chem. Soc., 88 (1966) 7010),
The amount of change was very small.

[0008]

In the present invention, by introducing an asymmetric molecule into a diarylethene molecule, a chiral induction of a ring-closed compound having a helicene-like structure is carried out, and one asymmetric structure of helicene is photoinduced. The inventors have found that they can be generated and induce a high optical rotation unlike the case of induced optical rotation, and have completed the present invention.

That is, the present invention has the following general formula

[0010]

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(Where X is

[0012]

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A group represented by: wherein R 7 is a hydrogen atom, an optionally substituted alkyl group or aryl group, Y and Z are an oxygen atom, a sulfur atom or an optionally substituted NH group, R ¹ and R ⁴ represents an alkyl group, an alkoxy group or an alkoxycarbonyl group, R ² , R ³ , R ⁵ and R ⁶ represent an alkyl group, a hydrogen atom or a halogen atom, and R ^{1 to} R ⁶
Any of them have an asymmetric carbon atom, and R ² and R ³ and / or R ⁵ and R ⁶ may be bonded to each other to form a ring).

In the above general formula (1), X is

[0015]

[Chemical 6]

## STR3 ## wherein R ⁷ is a hydrogen atom, an optionally substituted alkyl group, or an aryl group.

When R ⁷ is specifically exemplified, the alkyl group which may be substituted is an alkyl group having 1 to 6 carbon atoms such as methyl group and propyl group; and an alkyl group having 6 to 14 carbon atoms such as phenyl group and toluyl group. Examples of the substituent include a halogen atom such as fluorine, chlorine and bromine; an alkyl group having 1 to 6 carbon atoms such as methyl group and propyl group; an aryl group having 6 to 14 carbon atoms such as phenyl group and toluyl group. Group; aralkyl group having 7 to 15 carbon atoms such as benzyl group; alkoxy group having 1 to 6 carbon atoms such as methoxy group and propoxy group;
Examples include a cyanomethyl group; an alkoxycarbonylalkylene group such as a methoxycarbonylmethylene group; an alkoxyalkylene group such as a methoxyethylene group; a nitro group; an amino group.

In the general formula (1), Y and Z are oxygen atom, sulfur atom or NH group, and hydrogen of NH group may be substituted. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms such as a methyl group and an aryl group such as a phenyl group.

In the above general formula (1), R ¹ and R ⁴ are an alkyl group, an alkoxy group or an alkoxycarbonyl group. When the alkyl group does not have an asymmetric carbon, the alkyl group is a carbon such as a methyl group or an isopropyl group. An alkyl group having 1 to 6 carbon atoms; an alkoxy group having no asymmetric carbon atom, such as an ethoxy group, a propyl group, and an alkoxy group having 1 to 6 carbon atoms; an alkoxycarbonyl group having no asymmetric carbon atom, methoxy Examples thereof include alkoxycarbonyl groups having 2 to 7 carbon atoms such as carbonyl group and ethoxycarbonyl group.

In the above general formula (1), R ² , R ³ , R ⁵ and R ⁶ represent an alkyl group, a hydrogen atom or a halogen atom, and in the case of having no asymmetric carbon, the alkyl group is a methyl group, An alkyl group having 1 to 6 carbon atoms such as an isopropyl group; examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom.

R ² and R ³ and / or R ⁵ and R ⁶ may be bonded to each other to form a ring.
Alternatively, it is preferably condensed with an unsaturated heterocycle containing X to form a benzofuran ring, a benzothiophene ring, or an indole ring.

In the diarylethene compound of the present invention, it is essential that any of R ^{1 to} R ⁶ has an asymmetric carbon. Specific examples of the substituent having an asymmetric carbon atom for R ¹ and R ² include an asymmetric carbon-containing alkyl group such as a 2-butyl group, a 2-heptyl group, a 2-nonyl group and a menthyl group; a 2-butoxy group. , 2-heptoxy group, 2-nonyloxy group, menthyloxy group and other asymmetric carbon-containing alkoxy groups; 2-butoxycarbonyl group, 2-heptoxycarbonyl group, 2-nonyloxycarbonyl group, menthyloxycarbonyl group and the like. Examples of the asymmetric carbon-containing alkoxycarbonyl group include a 2-butyl group as a more specific example of the substituent having an asymmetric carbon for R ² , R ³ , R ⁵ and R ⁶ .
Examples thereof include asymmetric carbon-containing alkyl groups such as 2-heptyl group, 2-nonyl group and menthyl group.

The diarylethene compound of the present invention is synthesized by the following method.

X is

[0025]

[Chemical 7]

In the case of

[0027]

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As described above, it can be synthesized by condensing a 3-oxamoyl-substituted unsaturated heterocyclic compound and an unsaturated heterocyclic 3-acetic acid chloride.

X is

[0030]

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In the case of

[0032]

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As described above, it can be synthesized by condensing a 3-cyanomethyl-substituted unsaturated heterocyclic group and then hydrolyzing it to form an acid anhydride.

X is

[0035]

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In the case of

[0037]

[Chemical 12]

As described above, it can be synthesized by reacting a 3-lithio unsaturated heterocyclic compound with a cycloperfluoroalkene derivative.

[0039]

INDUSTRIAL APPLICABILITY In the present invention, by introducing an asymmetric molecule into a diarylethene molecule, it is possible to induce photoasymmetry of a ring-closed compound having a helicene-like structure and photogenerate one asymmetric structure of helicene. Therefore, unlike the case of the induced optical rotation, a high optical rotation can be induced.

[0040]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 2- (2-Methyl-3-benzothienyl)-(2-1)
Synthesis of Menthyl-3-benzothienyl) -N-cyanomethylmaleimide (4)

[0042]

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2-Methyl-in a 100 ml three-necked flask.
0.922 g (4.47 mmo) 3-benzothienyl acetic acid
l) and 1.422 g (11.2 m) of oxalyl chloride
mol) and 40 ml of dry benzene were added, and the mixture was stirred at room temperature for 2 hours and under reflux conditions for 1 hour. After distilling off the solvent, 25 ml of 1,2-dichloroethane was added.

This solution was prepared in advance.
-(L-Mentoxy) -3- (cyanomethyloxamoyl) benzothiophene 1.365 g (3.425 mmo)
l), 15 ml of triethylamine and 2 of dichloroethane
The mixture was added dropwise to 5 ml of the mixed solution at room temperature. After stirring for 48 hours as it was, diluted hydrochloric acid was added and the mixture was extracted with chloroform. The organic layer was dried over anhydrous magnesium sulfate. The solvent was evaporated, the obtained liquid was separated by a column, and 2- (2-methyl-3-benzothienyl) -3- (2-1-menthyl-3) was used.
-Benzothienyl) -N-cyanomethylmaleimide (A) was obtained. (1.378 g, 71% yield) This compound was obtained as a reddish orange liquid (minute droplets having a decomposition point of 86 ° C).

When 1H-NMR (in a CDCl3 solution) was measured, 9H based on methyl of the menthyl group and 6 based on methylene were found in the vicinity of δ = 0.55 to 2.41 ppm.
The peaks of H, 3H based on methine, and 3H based on the methyl group bound to thiophene were observed, and the peak of 1H of methine bound to oxygen of the menthyloxy group was observed near δ = 3.62 to 3.74 ppm. Δ = 4.51 ppm
A 2H peak of methylene of the cyanomethyl group was observed in the vicinity, and an 8H peak of the benzothiophene ring was observed in the vicinity of δ = 6.88 to 7.63 ppm. As a result of mass spectrometry, spectra were obtained at 430 (C10H19 +), 401, 290 and 83 with an intensity ratio of 18, 12, 18, 100. Elemental analysis showed C: 69.85%, H:
6.05%, N: 4.94%, calculated value C: 96.69
%, N: 5.67%, N: 4.93%.
The compound (A) was identified by the above analysis.

When the hexane solution of (A) is irradiated with light of 450 nm, the two diastereomers (B1) and (B
2) was obtained. When 1 H-NMR of these compounds was measured, almost the same δ = 0.55 to 2.41 ppm showed that methyl-based 9H of the menthyl group, methylene-based 6H, methine-based 3H, and ring-closed thiophene. A peak of 3H was observed based on the bonded methyl group, and δ =
A peak of 1H of methine bound to the oxygen of the menthyloxy group was observed at around 4.17 to 4.23 ppm, and δ =
2H of cyanomethyl group methylene around 4.60 ppm
The peak of 8H of the closed benzothiophene ring was observed in the vicinity of δ = 7.15 to 9.25 ppm.

From this, (B1) and (B2) were identified as the following structures.

[0048]

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The optical rotation of these is measured to be 633 nm.
Thus, large optical rotations of + 1300 ° and -1300 ° were obtained.

Example 2 The l-menthol group in Example 1 was replaced with a d-menthol group, and the same synthesis was carried out to obtain the following compound (C).

[0051]

[Chemical 15]

When 1 H-NMR (in a CDCl 3 solution) was measured, 9H based on methyl of the menthyl group and 6 based on methylene were found in the vicinity of δ = 0.55 to 2.41 ppm.
The peaks of H, 3H based on methine, and 3H based on the methyl group bound to thiophene were observed, and the peak of 1H of methine bound to oxygen of the menthyloxy group was observed near δ = 3.62 to 3.74 ppm. Δ = 4.51 ppm
A 2H peak of methylene of the cyanomethyl group was observed in the vicinity, and an 8H peak of the benzothiophene ring was observed in the vicinity of δ = 6.88 to 7.63 ppm.

The enantiomers obtained by irradiating (C) with light of 450 nm were + 1300 ° and -1300, respectively.
A degree of optical rotation was given.

Example 3 2- (2-Methyl-3-benzothienyl) -3- (2-
Synthesis of sec-butoxy-3-benzothienyl) -N-cyanomethylmaleimide (D).

[0055]

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2-Methyl-3 in a 50 ml three neck flask
-Benzothienyl acetic acid 0.222 g (1.08 mmo
l) and 0.355 g of oxalyl chloride (2.24 m
mol) and 15 ml of dry benzene were added, and the mixture was stirred at room temperature for 2 hours and under reflux conditions for 1 hour. After the solvent was distilled off, 20 ml of 1,2-dichloroethane was added.

This solution was prepared in advance.
-(Sec-Butoxy) -3- (cyanomethyloxamoyl) benzothiophene 0.257 g (0.812 mm)
ol), 4.2 ml of triethylamine and 20 ml of dichloroethane were added dropwise at room temperature. 7 as it is
After stirring for 2 hours, diluted hydrochloric acid was added and the mixture was extracted with chloroform. The organic layer was dried over anhydrous magnesium sulfate. The solvent was distilled off, the obtained liquid was separated on a column, and 2- (2-
Methyl-3-benzothienyl) -3- (2-sec-butoxy-3-benzothienyl) -N-cyanomethylmaleimide (D) was obtained. (0.212 g, 63% yield) This compound was obtained as a reddish orange liquid (minute droplets having a decomposition point of 109-110 ° C). 1H-NMR (CDC
13 solution), δ = 0.53 to 2.
Peaks of 6H based on methyl of sec-butoxy group, 2H based on methylene and 3H based on methyl group bound to thiophene were observed at around 53 ppm, and sec-butoxy at around δ = 3.98 to 4.07 ppm. The 1H peak of methine bound to the base oxygen was observed, and δ = 4.61p
A methylene 2H peak of the cyanomethyl group was observed near pm, and a benzothiophene ring 8H peak was observed near δ = 7.03 to 7.70 ppm.

CD spectra of two diastereomers obtained by irradiating (D) with light of 450 nm were measured. The results are shown in FIG.

Example 4 Compound (A) was dissolved in toluene (1.2 × 10 −4 mo)
1 / l) and 450 nm light and light having a wavelength of 570 nm or more were alternately irradiated, and the change in optical rotation at 633 nm was measured. At 633 nm, the ring-closure compound of the compound (A) has no absorption, and the photochromic reaction is not induced. The results are shown in FIG. It was observed that the optical rotation changed reversibly. This is a result of the asymmetric induction in the ring closure reaction due to the presence of the asymmetric menthol group. By using 633 nm light, it became possible to read the recording nondestructively.

[Brief description of drawings]

FIG. 1 is a diagram showing CD spectra of two diastereomers obtained by irradiating (D) with light.

FIG. 2 is a view showing a change in optical rotation by light irradiation of the toluene solution of (A).

Claims (3)

[Claims] 1. The following general formula: (In the formula, X is Wherein R ⁷ is a hydrogen atom, an optionally substituted alkyl group or aryl group, Y and Z are an oxygen atom, a sulfur atom or an optionally substituted NH group, R ¹
And R ⁴ is an alkyl group, an alkoxy group or an alkoxycarbonyl group, R ² , R ³ , R ⁵ and R ⁶ are alkyl groups,
Hydrogen atom or halogen atom, any one of R ^{1 to} R ⁶ has an asymmetric carbon atom, and R ² and R ³ and / or R ⁵ and R ⁶ may be bonded to each other to form a ring). Diarylethene compounds represented. 2. X is R is a sulfur atom, R ² and R ³ and R ⁵ and R ⁶ are bonded to each other to form an aromatic carbocycle.
The diarylethene compound according to claim 1, wherein ¹ is an alkyl group and R ⁴ is an alkoxy group having an asymmetric carbon. 3. A photochromic material comprising the diarylethene compound according to claim 1 or 2.