Photochromic Compounds

Abstract

To provide a photochromic compound that is transparent in an open ring state and can absorb light over the entire visible region in a close ring state, with its absorption observed more uniformly.SOLUTION: A compound is represented by one of the following formulae (I) and (I)' [where R1-R4 independently represent a group selected from the group consisting of H, a hydrocarbon group, a silyl group, a heterocyclic group, an electron-withdrawing group, an electron-donating group and a substituent containing a heteroatom, R1 and R2 may be bound together to form a ring, X1 is a heteroatom, and A is a heterocyclic compound-derived group].SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photochromic compound. [Background technology]

[0002] The phenomenon of reversible color change upon light irradiation is called photochromism, and compounds that exhibit this phenomenon are called photochromic compounds. Photochromic compounds are expected to be used in light-control materials, optical recording materials, holographic materials, and other applications.

[0003] Diarylethenes, which have five-membered heterocyclic rings as aryl groups, are known as photochromic compounds. These diarylethenes are generally colorless in the open ring form, but exhibit various colorations in the closed ring form depending on their structure.

[0004] For example, Patent Document 1 discloses a compound that has strong absorption around 450 nm and can develop a brown color, and Non-Patent Document 1 discloses a compound that can develop a blue color. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5337927 [Non-patent literature]

[0006] [Non-Patent Document 1] C. Zheng et al.,Dyes and Pigments,2013,vol.98,p.565-574 Summary of the Invention [Problem to be solved by the invention]

[0007] The compounds described in Patent Document 1 and Non-Patent Document 1 can produce brown or blue colors. On the other hand, when the purpose is, for example, anti-glare, it is required that the compounds uniformly absorb light over the entire visible range.

[0008] However, when the compounds described in Patent Document 1 and Non-Patent Document 1 are used as light-modulating materials, a large amount of the light-modulating material must be mixed in order to uniformly absorb light across the entire visible range. Therefore, when forming a film, for example, the material concentration in the film becomes high, which can cause aggregation of the material, potentially resulting in color unevenness.

[0009] Therefore, an object of the present invention is to provide a photochromic compound which is transparent in its ring-open form and can absorb light over the entire visible range in its ring-closed form, and which can absorb the light more uniformly. [Means for solving the problem]

[0010] The present inventors have conducted extensive research to solve the above problems, and as a result have found that a hetero-fused ring structure having a structure in which a substituted amino group is bonded can absorb light over the entire visible range in its closed ring state, and can achieve more uniform absorption, thereby completing the present invention.

[0011] That is, according to one aspect of the present invention, there is provided a compound represented by any one of the following formulas (I) and (I)'.

[0012] [ka]

[0013] In each of formulas (I) and (I)′, R1 to R4 each independently represent a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted hydrocarbon group, a substituted or unsubstituted silyl group, a substituted or unsubstituted heterocyclic group, an electron-withdrawing group, an electron-donating group, and a substituent containing a heteroatom, and R1 and R2 may be bonded to each other to form a ring; X1 is a heteroatom, A is a group derived from a heterocyclic compound. [Effects of the Invention]

[0014] According to the present invention, there is provided a photochromic compound which is transparent in its ring-open form and can absorb light over the entire visible range in its ring-closed form, and which can absorb light more uniformly. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a graph showing the absorption spectrum of Compound 1′ of an example. [Figure 2] 1 is a graph showing the absorption spectra of compounds A to C of the examples. [Figure 3] 1 is a graph showing the absorption spectra of compounds 1 and 1′ of the examples. [Figure 4] 1 is a graph showing the absorption spectra of compounds D to F of the examples. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will be described below, but the present invention is not limited to the following embodiment.

[0017] In this specification, the range "X to Y" means "X or more and Y or less." Unless otherwise specified, operations and measurements of physical properties are performed at room temperature (20 to 25°C) and a relative humidity of 40 to 50% RH.

[0018] One aspect of the present invention is a compound represented by any one of the following formulas (I) and (I)'.

[0019] [ka]

[0020] In each of formulas (I) and (I)′, R1 to R4 are each independently a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted hydrocarbon group, a substituted or unsubstituted silyl group (-SiH3), a substituted or unsubstituted heterocyclic group, an electron-withdrawing group, an electron-donating group, and a substituent containing a heteroatom; R1 and R2 may be bonded to each other to form a ring; X1 is a heteroatom; and A is a group derived from a heterocyclic compound.

[0021] In this specification, the compound represented by either one of the above formulas (I) and (I)' is also simply referred to as "the compound according to the present invention."

[0022] The compound according to the present invention is transparent in its ring-open form (compound represented by formula (I)), and can absorb light over the entire visible range in its ring-closed form (compound represented by formula (I)'), with the absorption being more uniform. The reversible interconversion between the ring-open form and the ring-closed form occurs only upon irradiation with light.

[0023] The compound described in Non-Patent Document 1 has low absorption around 470 nm and cannot absorb uniformly across the entire visible range. Therefore, when uniform absorption across the entire visible range is required for anti-glare purposes, for example, it is necessary to mix multiple light-modulating materials. Therefore, when producing an anti-glare film, for example, the concentration of the light-modulating material in the film increases, which can cause aggregation of the light-modulating material. This can easily cause color unevenness.

[0024] On the other hand, the compound according to the present invention contains a structure having a substituted amino group (the structure on the left side in formulas (I) and (I)'), and therefore can have higher absorption in the range of 400 to 500 nm compared to the compound described in Non-Patent Document 1. This makes it possible to absorb light more uniformly over the entire visible range.

[0025] In formulas (I) and (I)', the hydrocarbon group may be, for example, any of a straight-chain, branched-chain, or cyclic hydrocarbon group. From the viewpoint of further exerting the effects of the present invention, the hydrocarbon group is preferably a saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, and more preferably a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms, a straight-chain or branched-chain alkynyl group having 2 to 20 carbon atoms, a straight-chain or branched-chain alkenyl group having 2 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0026] In formulas (I) and (I)', examples of the alkyl group having 1 to 20 carbon atoms include straight-chain alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, and n-hexadecyl; isopropyl, isobutyl, sec-butyl, tert-butyl, and isoamyl. Examples of branched alkyl groups include a tert-pentyl group, a neopentyl group, a 1-methylpentyl group, a 4-methyl-2-pentyl group, a 3,3-dimethylbutyl group, a 2-ethylbutyl group, a 1-methylhexyl group, a tert-octyl group, a 1-methylheptyl group, a 2-ethylhexyl group, a 2-propylpentyl group, a 2,2-dimethylheptyl group, a 2,6-dimethyl-4-heptyl group, a 3,5,5-trimethylhexyl group, a 1-methyldecyl group, and a 1-hexylheptyl group.

[0027] In formulas (I) and (I)', examples of the alkynyl group having 2 to 20 carbon atoms include an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 3-butynyl group, a 3-methyl-1-propynyl group, a 2-methyl-3-propynyl group, a pentynyl group, a 1-hexynyl group, a 3-methyl-1-butynyl group, and a 3,3-dimethyl-1-butynyl group.

[0028] In formulas (I) and (I)', examples of the alkenyl group having 2 to 20 carbon atoms include a vinyl group, an allyl group, an isopropenyl group, a 1-butenyl group, a 2-butenyl group, a 2-methyl-2-propenyl group, a 1-methyl-2-propenyl group, a 2-methyl-1-propenyl group, a pentenyl group, a 1-hexenyl group, and a 3,3-dimethyl-1-butenyl group.

[0029] In formulas (I) and (I)', examples of the aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, a 2-naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, a naphthacenyl group, an indenyl group, an azulenyl group, an anthracenyl group, a triphenylenyl group, and a chrysenyl group.

[0030] In formulae (I) and (I)′, the heterocyclic group may be either an aromatic heterocyclic group having 2 to 20 carbon atoms or a non-aromatic heterocyclic group having 2 to 20 carbon atoms.

[0031] Examples of aromatic heterocyclic groups having 2 to 20 carbon atoms include a thienyl group, a furanyl group, a pyrrolyl group, a pyrazolyl group, an imidazolyl group, a pyridyl group, a pyridazinyl group, a pyrimidinyl group, a pyrazinyl group, a triazolyl group, a tetrazolyl group, a triazinyl group, a benzothienyl group, a benzimidazolyl group, an indolyl group, an isoindolyl group, a quinolinyl group, an isoquinolinyl group, a quinazolinyl group, a quinoxalinyl group, a naphthyridinyl group, an acridinyl group, a carbazolyl group, and a dibenzothienyl group.

[0032] Examples of the non-aromatic heterocyclic group having 2 to 20 carbon atoms include a pyrrolidinyl group, a tetrahydrofuranyl group, a tetrahydrothienyl group, a piperidinyl group, a tetrahydropyranyl group, a tetrahydrothiopyranyl group, a dioxanyl group, a morpholyl group, and a dioxolanyl group.

[0033] In formulas (I) and (I)', the electron-withdrawing group, also called an electron-accepting group, is an atomic group that attracts electrons from the substituted atomic group due to the inductive effect or resonance effect in organic electronics. Examples of electron-withdrawing groups include those with a positive value for the Hammett's substituent constant (σp(para)). The Hammett's substituent constant (σp(para)) can be found in the Revised 5th Edition of the Basic Chemistry Handbook (page II-380; edited by the Chemical Society of Japan, Maruzen Co., Ltd.).

[0034] Examples of the electron-withdrawing group include a halogeno group (preferably a fluoro group, a chloro group, or a bromo group), a halogenoalkyl group (preferably a perhalogenoalkyl group having 1 to 3 carbon atoms), a cyano group, an alkoxycarbonyl group (an ester group), a carboxy group (a carboxylic acid group), a carboxylic acid ester group, a carboxylic acid amide group, a sulfo group (a sulfonic acid group), a nitro group, a dicyanoethylene group, and an aldehyde group.

[0035] In formulas (I) and (I)', the electron-donating group is an atomic group that donates electrons to the substituted atomic group due to the inductive effect or resonance effect in organic electronic theory. Examples of electron-donating groups include those whose Hammett's substituent constant (σp(para)) is a negative value. The Hammett's substituent constant (σp(para)) can be cited from the Revised 5th Edition of the Basic Chemistry Handbook (page II-380; edited by the Chemical Society of Japan, Maruzen Co., Ltd.).

[0036] Examples of the electron-donating group include an alkyl group (preferably a linear or branched alkyl group having 1 to 4 carbon atoms), an aromatic hydrocarbon group (preferably an aromatic hydrocarbon group having 6 to 10 or 6 to 20 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 4 carbon atoms), an alkylthio group (preferably an alkylthio group having 1 to 2 carbon atoms (methylthio group, ethylthio group)), an aromatic heterocyclic group (preferably an aromatic heterocyclic group having 2 to 20 carbon atoms), an amino group, an amide group, a sulfonamide group, a hydroxyl group, a thiol group, a benzothiazole group, and an indolinyl group.

[0037] Examples of the alkoxy group include linear alkoxy groups such as methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-undecyloxy, n-dodecyloxy, n-tridecyloxy, n-tetradecyloxy, n-pentadecyloxy, and n-hexadecyloxy; isopropoxy, tert-butoxy, and 1-methylpentyloxy. branched-chain alkoxy groups such as a 4-methyl-2-pentyloxy group, a 3,3-dimethylbutyloxy group, a 2-ethylbutyloxy group, a 1-methylhexyloxy group, a tert-octyloxy group, a 1-methylheptyloxy group, a 2-ethylhexyloxy group, a 2-propylpentyloxy group, a 2,2-dimethylheptyloxy group, a 2,6-dimethyl-4-heptyloxy group, a 3,5,5-trimethylhexyloxy group, a 1-methyldecyloxy group, and a 1-hexylheptyloxy group.

[0038] Examples of the substituent containing a hetero atom include an alkoxy group (preferably an alkoxy group having 1 to 4 carbon atoms), an alkylamino group, an alkyl ether group, a hydroxyalkyl group, an alkylthio group, an acyloxy group, an alkylcarboxylic acid ester group, an alkylcarboxylic acid amide group, an N-alkylcarbamoyl group, an N,N-dialkylcarbamoyl group, an alkylsulfonyl group, a halogenated alkyl group, a pyrrolyl group, a pyridyl group, a naphthyl group, a pyrrolidinyl group, a piperidyl group, a perhydroindolyl group, a perhydroisoindolyl group, a perhydroquinolyl group, a perhydroisoquinolyl group, a perhydrocarbazolyl group, a perhydroacridinyl group, a furyl group, a pyranyl group, a perhydrofuryl group, and a thienyl group.

[0039] When the hydrocarbon group, silyl group, or heterocyclic group has a substituent, the substituent to be introduced is not particularly limited, and examples of the substituent to be introduced include a halogeno group, an unsubstituted alkyl group, an unsubstituted alkoxy group, and combinations thereof.

[0040] In formulas (I) and (I)', from the viewpoint of further exhibiting the effects of the present invention, R1 and R2 are each independently preferably a substituted or unsubstituted hydrocarbon group, more preferably a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, and even more preferably a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms.

[0041] In a preferred embodiment, from the viewpoint of further exhibiting the effects of the present invention, R1 and R2 each independently represent a linear or branched hydrocarbon group, more preferably a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 4 carbon atoms, or a substituted or unsubstituted alkenyl group having 2 to 4 carbon atoms, even more preferably a methyl group, ethyl group, n-propyl group, n-butyl group, isopropyl group, isobutyl group, sec-butyl group, or tert-butyl group, and particularly preferably a methyl group.

[0042] In a preferred embodiment, from the viewpoint of achieving more uniform light absorption across the entire visible range, R1 and R2 are each independently an unsubstituted phenyl group or a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms, more preferably a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms, even more preferably a methylphenyl group or a tert-butylphenyl group, and particularly preferably a tert-butylphenyl group. When the phenyl group is substituted with an alkyl group having 1 to 4 carbon atoms, the position of the substituent may be any of the ortho-, meta-, or para-position, and is preferably the para-position.

[0043] In formulas (I) and (I)′, R3 is, from the viewpoint of being able to more effectively exhibit the effects of the present invention, a substituted or unsubstituted hydrocarbon group or a substituted or unsubstituted heterocyclic group, more preferably a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted aromatic heterocyclic group, and particularly preferably an unsubstituted hydrocarbon group.

[0044] In a preferred embodiment, from the viewpoint of further exerting the effects of the present invention, R3 is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, more preferably a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, still more preferably a methyl group, ethyl group, n-propyl group, n-butyl group, isopropyl group, isobutyl group, sec-butyl group or tert-butyl group, and particularly preferably a methyl group.

[0045] In a preferred embodiment, from the viewpoint of red-shifting the absorption spectrum, R3 is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, more preferably a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, still more preferably a phenyl group, 1-naphthyl group, 2-naphthyl group, anthryl group, phenanthryl group, pyrenyl group, naphthacenyl group, indenyl group, azulenyl group, anthracenyl group, triphenylenyl group, or chrysenyl group, and particularly preferably a phenyl group.

[0046] By red-shifting the absorption spectrum, coloring and decoloring can be controlled not only by ultraviolet light but also by infrared light.

[0047] In formulae (I) and (I)', R4 is preferably a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, or an electron-withdrawing group, from the viewpoint of being able to more effectively exhibit the effects of the present invention.

[0048] In a preferred embodiment, R4 is an electron-withdrawing group, more preferably a dicyanoethylene group, from the viewpoint of red-shifting the absorption spectrum.

[0049] In a preferred embodiment, R4 is a phenyl group or an aldehyde group substituted with an alkoxy group having 1 to 4 carbon atoms, more preferably a methoxyphenyl group or an aldehyde group, and even more preferably an aldehyde group, from the viewpoint of further exerting the effects of the present invention.

[0050] In a more preferred embodiment, R1 and R2 are each independently a methyl group, a methylphenyl group, or a tert-butylphenyl group, R3 is a methyl group or a phenyl group, and R4 is a hydrogen atom, a methoxyphenyl group, a dicyanoethylene group, or an aldehyde group, and R1 and R2 are preferably the same substituent.

[0051] In formulae (I) and (I)', X1 is a heteroatom, preferably a nitrogen atom.

[0052] In formulas (I) and (I)′, A is a group derived from a heterocyclic compound. Examples of the heterocyclic compound include heterocyclic compounds having 5 to 14 ring atoms, such as thiophene, thiazole, oxazole, furan, benzothiophene, and benzofuran.

[0053] In a preferred embodiment, the compound according to the present invention is a compound represented by any one of the following formulae (I-1) and (I-1)', from the viewpoint of being able to further exert the effects of the present invention.

[0054] [ka]

[0055] In each of formulas (I-1) and (I-1)', R1 to R4 and X1 are as defined above, and X2 is a heteroatom.

[0056] In a preferred embodiment, X2 is an oxygen atom, a nitrogen atom or a sulfur atom, more preferably a sulfur atom.

[0057] In a more preferred embodiment, the compound according to the present invention is a compound represented by any one of the following formulae (I-2) and (I-2)', from the viewpoint of being able to further exert the effects of the present invention.

[0058] [ka]

[0059] In each of the formulas (I-2) and (I-2)', R1 to R4 are as defined above.

[0060] The synthesis method of the compound according to the present invention is not particularly limited, and a conventionally known synthesis method can be applied. For example, taking Compound 1 of Formula (I), in which R1 and R2 are 4-tert-butylphenyl groups, R3 is a phenyl group, R4 is a 4-methoxyphenyl group, X1 is a nitrogen atom, and A is a group derived from thiophene, as an example, Compound 1 can be synthesized according to the following Scheme 1.

[0061] [ka]

[0062] In the above scheme 1, compound 3 and compound 4 can be synthesized according to the method described in S. Lee et al., Org. Lett., 2012, 14, 2238-2241.

[0063] In the above scheme 1, compound 5 can be synthesized according to the method described in F. Sun et al., Tetrahedron, 2003, 59, 7615-7621.

[0064] In the above scheme 1, compound 7 can be synthesized according to the method described in CL Dong et al., Org. Lett., 2020, 22, 1076-1080.

[0065] In the above scheme 1, compound 8 can be synthesized according to the method described in P. Ni et al., Org. Lett., 2019, 21, 3518-3522.

[0066] In the above scheme 1, compound 9 can be synthesized, for example, by the following method.

[0067] Compound 8 is dissolved in dehydrated toluene, and the resulting solution is mixed with bis(4-tert-butylphenyl)amine, sodium tert-butoxide, tri-tert-butylphosphonium tetrafluoroborate, and tris(dibenzylideneacetone)dipalladium(0). The mixture is refluxed overnight under an argon atmosphere. The reaction mixture is extracted with ethyl acetate, and the organic layer is washed, dried, concentrated, and purified to give compound 9.

[0068] In the above scheme 1, compound 10 can be synthesized, for example, by the following method.

[0069] Compound 9 is dissolved in a dichloromethane / methanol (volume ratio: 5 / 2) mixture, and calcium carbonate and benzyltrimethylammonium tribromide (BTMABr3) are added to the reaction solution, which is then stirred at room temperature for 30 minutes. The reaction solution is extracted with dichloromethane, and the organic layer is washed, dried, concentrated, and purified to obtain compound 10.

[0070] In the above scheme 1, compound 1 can be synthesized, for example, by the following method.

[0071] To a reaction solution containing compound 10 dissolved in anhydrous tetrahydrofuran, a 1.6M n-butyllithium hexane solution is slowly added dropwise at -78°C under an argon atmosphere. After stirring at that temperature for 30 minutes, a solution containing compound 5 dissolved in anhydrous tetrahydrofuran is slowly added dropwise at -78°C. After stirring at that temperature for 1 hour, the temperature is slowly raised to room temperature. Water is added to the reaction solution to quench the reaction. The reaction solution is extracted with ethyl acetate, and the organic layer is washed, dried, concentrated, and purified to obtain compound 1.

[0072] Furthermore, taking as an example Compound 1' of Formula (I), in which R1 and R2 are 4-tert-butylphenyl groups, R3 is a methyl group, R4 is a 4-methoxyphenyl group, X1 is a nitrogen atom, and A is a group derived from thiophene, it can be synthesized according to the following Scheme 2.

[0073] [ka]

[0074] In the above scheme 2, compounds 3 to 5, 9, 10 and 1′ can be synthesized in the same manner as in the above scheme 1.

[0075] In the above scheme 2, compound 7 can be synthesized according to the method described in X. Song et al., Org. Lett., 2017, 19, 6542-6545.

[0076] The compound according to the present invention can absorb light more uniformly over the entire visible range, and is therefore suitable as a light-controlling material, and can be used in particular for applications requiring absorption over the entire visible range, such as anti-glare applications, and applications requiring black color development.

[0077] Therefore, one embodiment of the present invention is a light-modulating material comprising the compound of the present invention. The light-modulating material may be in a liquid or solid state.

[0078] When the light-modulating material is liquid, a solution in which the compound of the present invention is dissolved in a solvent can be used. The solvent is not particularly limited as long as it is colorless and can dissolve the compound of the present invention. Examples of the solvent include organic solvents, supercritical solvents, ionic liquids, and mixtures thereof.

[0079] When the light-modulating material is solid, the compound according to the present invention is dispersed in a solid matrix. Examples of solid matrices include crystalline solids or glassy (amorphous) solids, liquid crystals, and gels. Examples of components of the solid matrix include organic or inorganic low-molecular-weight compounds and organic or inorganic polymer compounds. For example, when providing anti-glare protection against light incident from a light source located outside (in front of) a moving body (vehicle), examples of the matrix include glassy (amorphous) solids and polymer matrices containing organic polymers. The solid light-modulating material can be used as glass, a film, etc. [Example]

[0080] The present invention will be described in more detail below with reference to examples, although the technical scope of the present invention is not limited to the following examples.

[0081] (Synthesis of Compound 1) Compound 1 was synthesized according to Scheme 1 shown below.

[0082] [ka]

[0083] Compound 2 (2-methylthiophene) and compound 6 (5-bromoindole) were purchased from Tokyo Chemical Industry Co., Ltd. Compounds 3 to 5, 7, and 8 were synthesized according to the following literature: Compounds 3 and 4: S. Lee, Y. You, K. Ohkubo, S. Fukuzumi and W. Nam, Org. Lett., 2012, 14, 2238-2241; Compound 5: F. Sun, F. Zhang, H. Guo, X. Zhou, R. Wang and F. Zhao, Tetrahedron, 2003, 59, 7615-7621; Compound 7: CL Dong, X. Ding, L.-Q. Huang, Y.-H. He and Z. Guan, Org. Lett., 2020, 22, 1076-1080; Compound 8: P. Ni, J. Tan, W. Zhao, H. Huang, F. Xiao and G.-J. Deng, Org. Lett., 2019, 21, 3518-3522.

[0084] Synthesis of compound 9

[0085] [ka]

[0086] Compound 8 (2.0 g, 7.0 mmol) was dissolved in anhydrous toluene (36 mL) and bis(4-tert-butylphenyl)amine (3.04 g, 10.8 mmol), sodium tert-butoxide (1.35 g, 14.0 mmol), tri-tert-butylphosphonium tetrafluoroborate (202 mg, 10 mol%), and tris(dibenzylideneacetone)dipalladium(0) (81 mg, 88 μmol) were added. The mixture was refluxed overnight under an argon atmosphere. The reaction solution was allowed to warm to room temperature, and the progress of the reaction was confirmed by TLC. The solution was extracted with ethyl acetate, and the organic layer was washed with brine. The organic layer was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by silica gel column chromatography (hexane:dichloromethane = 4:1 (volume ratio)) to give compound 9 as a white solid (yield: 2.1 g, 62%). 1H NMR (400 MHz, CD2Cl2)δ: 7.42-7.52 (m, 4H), 7.36-7.41 (m, 1H), 7.27-7.35 (m, 2H), 7.20 (d, J = 8 Hz, 2H), 7.02 (d, J = 8 Hz, 1H), 6.93 (d, J = 8 Hz, 2H), 6.42 (s, 1H), 3.71 (s, 3H), 1.27 (s, 18H); MS (MALDI) m / z = 487.42 [M+H] + (Exact Mass: 486.30).

[0087] NMR measurements were performed by dissolving 3 to 5 mg of the synthesized compound in 1 mL of a deuterated solvent (deuterated chloroform or deuterated dichloromethane) using an NMR spectrometer JNMEX400 spectrometer (manufactured by JEOL Ltd., magnetic field number: 400 MHz).

[0088] Synthesis of compound 10

[0089] [ka]

[0090] Compound 9 (1.7 g, 3.5 mmol) was dissolved in a dichloromethane / methanol (volume ratio: 5 / 2) mixed solution (17.5 mL). Calcium carbonate (1.0 g, 10.0 mmol) and benzyltrimethylammonium tribromide (BTMABr3) (1.5 g, 3.85 mmol) were added to the reaction solution and stirred at room temperature for 30 minutes. After confirming the progress of the reaction by TLC, the solution was extracted with dichloromethane, and the organic layer was washed with 2N aqueous hydrochloric acid. The organic layer was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by silica gel column chromatography (hexane:dichloromethane = 4:1 (volume ratio)) to obtain compound 10 as a white solid (yield: 2.0 g, quantitative yield). 1H NMR (400 MHz, DMSO-d6)δ: 7.48-7.56 (m, 6H), 7.23 (d, J = 8 Hz, 4H), 7.06 (s, 1H), 6.98 (d, J = 8 Hz, 1H), 6.85 (d, J = 8 Hz, 4H), 3.62 (s, 3H), 1.22 (s, 18H); MS (MALDI) m / z = 564.67 [M] + (Exact Mass: 564.21).

[0091] Synthesis of Compound 1

[0092] [ka]

[0093] To a reaction solution prepared by dissolving compound 10 (1.0 g, 1.77 mmol) in anhydrous tetrahydrofuran (17 mL), a 1.6 M n-butyllithium hexane solution (1.3 mL, 2.1 mmol) was slowly added dropwise at −78°C under an argon atmosphere. After stirring at that temperature for 30 minutes, a solution of compound 5 (860 mg, 2.2 mmol) in anhydrous tetrahydrofuran (5 mL) was slowly added dropwise at −78°C. After stirring at that temperature for 1 hour, the mixture was slowly warmed to room temperature. After confirming the progress of the reaction by TLC, water was added to the solution to quench the reaction. The organic layer was extracted with ethyl acetate, and washed with 2 N aqueous hydrochloric acid and brine. The organic layer was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by silica gel column chromatography (hexane:dichloromethane = 4:1 (volume ratio)) to obtain compound 1 as a pale yellow solid (yield: 1.0 g, 66%). 1H NMR (400 MHz, CD2Cl2)δ: 7.29 (t, J = 8 Hz, 2H), 7.15-7.26 (m, 10H), 6.91-6.97 (m, 5H), 6.87 (d, J = 8 Hz, 2H), 6.02 (s, 1H), 3.81 (s, 3H), 3.52 (s, 3H), 1.67 (s, 3H), 1.29 (s, 18H); MS (MALDI) m / z = 863.59 [M+H] + (Exact Mass: 862.34).

[0094] (Synthesis of Compound 1') Compound 1' was synthesized according to Scheme 2 shown below.

[0095] [ka]

[0096] Compound 2 (2-methylthiophene) and compound 6 (2-methyl-5-chloroindole) were purchased from Tokyo Chemical Industry Co., Ltd. Compounds 3 to 5 and 7 were synthesized according to the following literature: Compounds 3 and 4: S. Lee, Y. You, K. Ohkubo, S. Fukuzumi and W. Nam, Org. Lett., 2012, 14, 2238-2241; Compound 5: F. Sun, F. Zhang, H. Guo, X. Zhou, R. Wang and F. Zhao, Tetrahedron, 2003, 59, 7615-7621; Compound 7: X. Song, C. Xu, D. Du, Z. Zhao, D. Zhu and M. Wang, Org. Lett., 2017, 19, 6542-6545.

[0097] Synthesis of compound 8

[0098] [ka]

[0099] Compound 7 (1.0 g, 5.6 mmol) was dissolved in anhydrous toluene (28 mL) and bis(4-tert-butylphenyl)amine (2.4 g, 8.5 mmol), sodium tert-butoxide (1.07 g, 11.1 mmol), tri-tert-butylphosphonium tetrafluoroborate (161 mg, 10 mol%), and tris(dibenzylideneacetone)dipalladium(0) (64 mg, 2 mol%) were added. The mixture was refluxed overnight under an argon atmosphere. The reaction solution was allowed to warm to room temperature, and the progress of the reaction was confirmed by TLC. The solution was extracted with ethyl acetate, and the organic layer was washed with brine. The organic layer was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by silica gel column chromatography (hexane:dichloromethane = 4:1 (volume ratio)) to give compound 8 as a white solid (yield: 1.6 g, 68%). 1 H NMR (400 MHz, CDCl3)δ: 7.18-7. 21 (d, J = 8 Hz, 1H), 7.13-7.18 (m, 5H), 6.86-6.92 (m, 5H), 6.12 (brs, 1H), 3.60 (s, 3H), 2.36 (s, 3H), 1.25 (s, 18H); MS (MALDI) m / z = 425.64 [M+H] + (Exact Mass: 424.29).

[0100] Synthesis of compound 9 Compound 8 (300 mg, 0.7 mmol) was dissolved in a dichloromethane / methanol (volume ratio: 5 / 2) mixture (3.5 mL) to prepare a reaction solution. Calcium carbonate (200 mg, 2.0 mmol) and benzyltrimethylammonium tribromide (BTMABr3) (300 mg, 0.78 mmol) were added and the mixture was stirred at room temperature for 30 minutes. After confirming the progress of the reaction by TLC, the solution was extracted with dichloromethane, and the organic layer was washed with 2N aqueous hydrochloric acid. The organic layer was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by silica gel column chromatography (hexane:dichloromethane = 4:1) to give compound 9 as a white solid (yield: 360 mg, quantitative yield). 1 H NMR (400 MHz, CDCl3)δ: 7.19 (d, J = 8 Hz, 6H), 6.85-7.02 (m, 4H), 3.64 (brs, 3H), 2.38 (s, 3H), 1.27 (s, 18H); MS (MALDI) m / z = 502.14 [M] + (Exact Mass: 502.20).

[0101] Synthesis of Compound 1'

[0102] [ka]

[0103] To a reaction solution prepared by dissolving compound 9 (2.0 g, 4.0 mmol) in anhydrous tetrahydrofuran (35 mL), a 1.6 M n-butyllithium hexane solution (3.0 mL, 4.8 mmol) was slowly added dropwise at −78°C under an argon atmosphere. After stirring at that temperature for 30 minutes, a solution of compound 5 (2.0 g, 5.0 mmol) in anhydrous tetrahydrofuran (5 mL) was slowly added dropwise at −78°C. After stirring at that temperature for 1 hour, the mixture was slowly warmed to room temperature. After confirming the progress of the reaction by TLC, water was added to the solution to quench the reaction. The organic layer was extracted with ethyl acetate, and washed with 2 N aqueous hydrochloric acid and brine. The organic layer was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by silica gel column chromatography (hexane:dichloromethane = 3:1 (volume ratio)) to obtain compound 1' as a pale yellow solid (yield: 1.8 g, 54%). 1 H NMR (400 MHz, CD2Cl2)δ: 7.27-7.33 (m, 3H), 7.04-7.26 (m, 10H), 6.88 (d, J = 8 Hz, 2H), 6.82 (s, 1H), 3.83 (s, 3H), 3.58 (s, 3H), 1.97 (s, 3H), 1.71 (s, 3H), 1.28 (s, 18H); MS (MALDI) m / z = 801.45 [M+H] + (Exact Mass: 800.32).

[0104] (Example 1: Measurement of visible light absorptance) 10 μg of compound 1′ was dissolved in 3 mL of tetrahydrofuran, and the absorption spectrum was measured using an ultraviolet-visible spectrophotometer (U-3310, Hitachi High-Tech Science Corporation). The results are shown in FIG.

[0105] In FIG. 1, UV indicates the absorption spectrum of the closed-ring form after irradiation with 365 nm light for 30 seconds, and Vis indicates the absorption spectrum of the open-ring form after irradiation with 650 nm light for 3 minutes.

[0106] As shown in FIG. 1, Compound 1' is transparent in its ring-open form, and can absorb light across the entire visible range in its ring-closed form.

[0107] The visible light absorptance was calculated from the absorption spectrum. Specifically, the maximum absorbance in the visible range (λ = 400 to 700 nm) was calculated as A max In the visible range, the horizontal axis is max The area of ​​the absorption spectrum of the closed-ring isomer in the visible range was calculated as a percentage of the area of ​​the absorption spectrum of the closed-ring isomer in the visible range, assuming that the area occupied by the closed-ring isomer is 100%. The results are shown in Table 1.

[0108] [Table 1]

[0109] In Table 1, the visible light absorptance of the comparative compounds was calculated from the absorption spectrum (absorption spectrum having the highest peak at 583 nm) in Fig. 3(A) of Non-Patent Document 1 (C. Zheng et al., Dyes and Pigments, 2013, vol. 98, pp. 565-574).

[0110] As shown in Table 1, it can be seen that the closed-ring form of Compound 1' has a broader (more uniform) absorption spectrum in the visible range compared to the comparative compounds, and exhibits a high visible light absorptance.

[0111] (Example 2: Calculation of visible light absorptance)

[0112] [ka]

[0113] The absorption spectra of Compounds A to C were calculated using Gaussian 16 (Gaussian). Compound B has the same structure as the ring-closed form of Compound 1. Geo-opt:TD-DFT UV-Vis Spectra:CAM-B3LYP Excited states: 10 singles Medium:Vacuum.

[0114] In addition, the visible light absorptance was calculated from the absorption spectrum in the same manner as in Example 1. The results are shown in FIG.

[0115] [Table 2]

[0116] As shown in FIG. 2 and Table 2, it can be seen that compounds A to C have improved absorption peak intensities on the short wavelength side of visible light and can broadly absorb the entire visible light range.

[0117] (Example 3: Measurement of absorption spectrum) The absorption spectrum of Compound 1 was measured in the same manner as in Example 1. The results are shown in Figure 3 together with the absorption spectrum of Compound 1'.

[0118] As shown in Figure 3, when R3 of the compound according to the present invention is a phenyl group, it is possible to absorb broadly the entire visible light range and the absorption spectrum is red-shifted. This shows that Compound 1 can control coloring and decoloring not only by ultraviolet light but also by infrared light.

[0119] (Example 4: Calculation of absorption spectrum)

[0120] [ka]

[0121] The absorption spectra of Compounds D and E were calculated using Gaussian 16 (Gaussian) in the same manner as in Example 2. The results are shown in FIG.

[0122] As shown in Figure 4, the compound according to the present invention, in which R4 is an electron-withdrawing group (dicyanoethylene), can absorb broadly the entire visible light range and also red-shift the absorption spectrum. This indicates that the coloring and decoloring of compound E can be controlled not only by ultraviolet light but also by infrared light.

[0123] (Example 5: Calculation of absorption spectrum)

[0124] [ka]

[0125] The absorption spectrum of Compound F was calculated using Gaussian 16 (Gaussian) in the same manner as in Example 2. The results are shown in FIG.

[0126] In addition, the visible light absorptance was calculated from the absorption spectra of compounds E and F in the same manner as in Example 1. The results are shown in Table 3.

[0127] [Table 3]

[0128] As shown in FIG. 4 and Table 3, it can be seen that compound F has a broader absorption spectrum in the visible range and exhibits a higher visible light absorptance because R4 of the compound according to the present invention is an aldehyde group.

Claims

1. A compound represented by any one of the following formulas (I-2) and (I-2)′: 【Chemistry 1】 In each of formulas (I-2) and (I-2)′, R １ and R ２ are each independently a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms or an unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, R ３ is an unsubstituted alkyl group having 1 to 4 carbon atoms or an unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, R ４ is a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms.

2. The R ３ is an unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms.

3. The R ３ The compound according to claim 1 or 2, wherein is a phenyl group, a 1-naphthyl group, a 2-naphthyl group, an indenyl group, or an azulenyl group.

4. The R ３ The compound according to any one of claims 1 to 3, wherein is a phenyl group.

5. The R １ and the R ２ The compound according to any one of claims 1 to 4, wherein is a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms.

6. The R １ and the R ２ is a tert-butylphenyl group, and R ３ is a methyl group or a phenyl group, and R ４ is a methoxyphenyl group.

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