Azobenzene derivatives, methods for producing azobenzene derivatives, photothermal energy storage materials, adhesives, optical elements, and actuator materials

Abstract

Provided is an azobenzene derivative represented by formula (1). (In formula (1), R1 represents a C1-18 alkoxy group, R2 each independently represent a hydrogen atom or a C1-4 alkyl group, R3 represents a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxy group, R3 represents a functional group different than R1, X1 to X4 each independently represent a halogen atom or a C1-2 alkyl group, and one or more of X1 to X4 represents a halogen atom.)

Description

Technical Field

[0001] The present invention relates to an azobenzene derivative, a method for producing an azobenzene derivative, and a photothermal storage material, an adhesive, an optical element, and an actuator material containing the azobenzene derivative.

Background Art

[0002] Compounds and materials that can reversibly undergo a phase change between a solid and a liquid using light have been studied for applications such as reversible adhesion, actuators, and photothermal storage materials. Patent Document 1 discloses a macrocyclic azobenzene having a predetermined structure as a photoresponsive liquid crystal compound. Further, Patent Documents 2 and 3 disclose azobenzene derivatives having a predetermined structure. Further, Non-Patent Documents 1, 2, 3, and 4 disclose azobenzene derivatives substituted with a halogen.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

[0005] However, in order to melt the compounds described in Patent Documents 1 to 3 with light, it was necessary to use ultraviolet light. The inventors realized that ultraviolet light has high energy, which poses problems in terms of damage to materials and living organisms. They also realized that when using ultraviolet light, there is a problem in that the solar spectrum cannot be fully utilized. Furthermore, the inventors discovered that azobenzene, which is widely used in photoresponsive compounds, has a problem in that the cis isomer, which corresponds to the state in which it is molten in light, has low stability. Therefore, if azobenzene is left at room temperature, it will return to a solid state even if left in the dark. For example, when applying azobenzene as an adhesive, it is difficult to maintain a molten and detachable state for a long period of time. Similarly, when applying azobenzene as a light-based heat storage material, it is difficult to maintain a state in which it has stored light energy for a long period of time. On the other hand, Non-Patent Documents 1 to 4 disclose halogen-substituted azobenzene derivatives. Furthermore, the compounds disclosed in Non-Patent Documents 1 to 4 are shown to be capable of photoisomerization between trans and cis isomers only when the compounds are dissolved in a solvent and exposed to visible light, not ultraviolet light. However, the inventors realized that melting by visible light has not been achieved for any of the compounds disclosed in Non-Patent Documents 1 to 4.

[0006] Thus, conventional azobenzenes melt when irradiated with visible light, and it has been difficult to maintain this molten state (liquid phase) for an extended period of time due to molecular design limitations. Furthermore, molecular design that allows for adjustment of response characteristics to light wavelengths and photosensitivity had not been achieved due to the difficulty of molecular synthesis. As described above, the inventors of this invention realized that the problem is to provide a compound that melts when irradiated with visible light.

[0007] The present invention provides an azobenzene derivative that melts in visible light, a method for producing the same, and a photothermal energy storage material, adhesive, optical element, and actuator material containing the azobenzene derivative. [Means for solving the problem]

[0008] This invention provides the following: [1] An azobenzene derivative represented by the following formula (1). [ka] (In formula (1), R1 represents an alkoxy group having 1 to 18 carbon atoms, R2 independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R3 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, R3 represents a functional group different from R1, and X1 to X4 independently represent a halogen atom or an alkyl group having 1 to 2 carbon atoms, with one or more of X1 to X4 representing a halogen atom.) [2] The azobenzene derivative according to [1], wherein one or more of the R2s in formula (1) are branched C3-C4 alkyl groups. [3] The azobenzene derivative according to [1] or [2], wherein in formula (1), R1 represents an alkoxy group having 6 to 18 carbon atoms, X1 to X4 each independently represent a halogen atom, and X1 to X4 represent a combination of two or more halogen atoms. [4] An azobenzene derivative according to any one of [1] to [3], wherein X1 to X4 in formula (1) is a combination of two or more halogen atoms selected from the group consisting of fluorine atoms, chlorine atoms and bromine atoms. [5] An azobenzene derivative according to any one of [1] to [4], wherein in formula (1), X1 and X2 are the same halogen atom, and X3 and X4 are the same halogen atom different from X1 and X2. [6] An azobenzene derivative according to any one of [1] to [5], wherein X1 to X4 in formula (1) are a combination of a fluorine atom and a chlorine atom. [7] The azobenzene derivative according to any one of [1] to [6], wherein R2 in formula (1) is independently a hydrogen atom or a methyl group. [8] An azobenzene derivative according to any of [1] to [7] that can undergo a phase transition between a solid phase and a liquid phase by irradiation with visible light. [9] The azobenzene derivative described in [8], which undergoes a phase transition from a solid phase to a liquid phase when irradiated with visible light with a wavelength of 500 to 650 nm.

[10] An azobenzene derivative according to [8] or [9] that undergoes a phase transition from a liquid phase to a solid phase by irradiation with visible light having a wavelength of 400 to 500 nm. A method for producing an azobenzene derivative according to any of

[11] [1] to

[10] , Step (A) involves contacting at least one azobenzene derivative selected from the group consisting of an azobenzene derivative represented by the following formula (2-1), an azobenzene derivative represented by the following formula (2-2), and an azobenzene derivative represented by the following formula (2-3) with a halogenating agent in the presence of a palladium compound to obtain an azobenzene derivative represented by the following formula (3), A method for producing an azobenzene derivative, comprising the steps of: (A) deprotecting the acetoxy group of the azobenzene derivative represented by the following formula (3) obtained in step (A) to obtain the azobenzene derivative represented by the above formula (1); and (B) in this order. [ka] [ka] [ka] (In formulas (2-1), (2-2), and (2-3), R'1 represents an acetoxy group, R2 independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R3 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and X1 to X4 independently represent a halogen atom or an alkyl group having 1 to 2 carbon atoms.) [ka] (In formula (3), R'1 represents an acetoxy group, R2 independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R3 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and X1 to X4 independently represent a halogen atom or an alkyl group having 1 to 2 carbon atoms, with one or more of X1 to X4 representing a halogen atom.)

[12] In equations (2-1), (2-2), and (2-3) above, X1 to X4 each independently represent a halogen atom. A method for producing an azobenzene derivative according to

[11] , wherein in formula (3), X1 to X4 each independently represent a halogen atom, and X1 to X4 represent a combination of two or more halogen atoms. A photothermal energy storage material containing an azobenzene derivative as described in any of

[13] [1] to

[10] . An adhesive containing an azobenzene derivative as described in any of

[14] [1] to

[10] . An optical element containing an azobenzene derivative as described in any of

[15] [1] to

[10] . An actuator material containing an azobenzene derivative as described in any of

[16] [1] to

[10] . [Effects of the Invention]

[0009] The present invention provides an azobenzene derivative that melts in visible light, a method for producing the same, and a photothermal energy storage material, adhesive, optical element, and actuator material containing the azobenzene derivative. [Brief explanation of the drawing]

[0010] [Figure 1] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 2] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 3] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 4] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 5] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 6] Observation results of the sunlight irradiation experiment [Figure 7] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 8] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 9] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 10] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 11] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 12] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 13] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 14] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 15] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 16] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 17] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 18] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Figure 19] Observation results of crystalline phase-isotropic phase transition using polarized optical microscopy [Modes for carrying out the invention]

[0011] The present invention will be described in detail below, but is not limited to the following description. When a numerical range is expressed as "XX or greater and YY or less" or "XX to YY," unless otherwise specified, it means a numerical range that includes the lower and upper limits. When a numerical range is expressed in steps, the upper and lower limits of each range can be combined in any way. Furthermore, in this disclosure, visible light refers to light with a wavelength of 400 to 700 nm.

[0012] Azobenzene derivatives are azobenzene derivatives represented by the following formula (1). [ka] (In formula (1), R1 represents an alkoxy group having 1 to 18 carbon atoms (preferably 3 to 18, more preferably 6 to 18, even more preferably 6 to 16, even more preferably 6 to 14, and particularly preferably 6 to 12); R2 independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms (preferably 1 to 2, preferably 3 to 4, and more preferably 1); R3 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms (preferably 1 to 2, preferably 3 to 4, and more preferably 1), or an alkoxy group having 1 to 4 carbon atoms (preferably 1 to 2, preferably 3 to 4, and more preferably 1); R3 represents a functional group different from R1; X1 to X4 independently represent a halogen atom or an alkyl group having 1 to 2 carbon atoms, and one or more of X1 to X4 represent a halogen atom.)

[0013] The azobenzene derivative having the structure represented by formula (1) above allows it to melt when irradiated with visible light and to maintain its molten state for a long period of time. The mechanism by which these effects are produced is not clear, but the inventors speculate as follows. Azobenzene derivatives having the structure represented by formula (1) above have an alkoxy group R1 at the first para position relative to the azo group, and a hydrogen atom, a relatively short alkyl group, or an alkoxy group different from R1, R3, at the second para position relative to the azo group. In this way, the asymmetric molecular structure of azobenzene derivatives makes it possible to control the strength of intermolecular interactions and packing in the crystalline state. Furthermore, if R1 is a relatively long alkoxy group (for example, with 6 to 18 carbon atoms), the strength of intermolecular interactions and packing in the crystalline state becomes even easier to control. Furthermore, azobenzene derivatives having the structure represented by formula (1) above contain one or more halogen atoms X1 to X4 in the molecule. The presence of one or more halogen atoms in an azobenzene derivative makes it easier to control the electron density of the azobenzene derivative, the strength of intermolecular interactions in the crystalline state, and the packing strength.

[0014] In formula (1) above, when R1 to R3 are alkyl groups or alkoxy groups, the alkyl groups and alkoxy groups may be linear or branched, but branching is preferred. Branching makes the asymmetry of the azobenzene derivative stronger, making it easier to control the strength of intermolecular interactions and packing in the crystalline state. Specifically, alkyl groups such as isopropyl groups and isobutyl groups, and alkoxy groups such as isopropoxy groups and isobutoxy groups are preferred.

[0015] Each of X1 to X4 independently represents a halogen atom or an alkyl group having 1 to 2 carbon atoms, and one or more of X1 to X4 represent a halogen atom. In formula (1) above, the halogen atoms represented by X1 to X4 are not particularly limited and may be fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, astatine atoms, or tennessine atoms. Each of X1 to X4 independently represents a halogen atom, and it is preferable that X1 to X4 represent a combination of two or more halogen atoms. Having two or more halogen atoms in an azobenzene derivative makes it easier to control the electron density of the azobenzene derivative, the strength of intermolecular interactions in the crystalline state, and the packing strength. In particular, it is preferable that X1 to X4 be a combination of two or more halogen atoms selected from the group consisting of fluorine atoms, chlorine atoms, bromine atoms, or iodine atoms, more preferably a combination of two or more halogen atoms selected from the group consisting of fluorine atoms, chlorine atoms, and bromine atoms, and even more preferably a combination of fluorine atoms and chlorine atoms. When X1 to X4 are a combination of two or more halogen atoms, X1 to X4 are not particularly limited, but it is more preferable that X1 and X2 are the same halogen atom, and X3 and X4 are the same halogen atom but different from X1 and X2.

[0016] The fact that the azobenzene derivative has the structure represented by formula (1) above can be confirmed by NMR measurement as described later.

[0017] Examples of azobenzene derivatives having the structure represented by formula (1) above include the following: 2,6-Dichloro-4-octoxy-2',6'-difluoroazobenzene, 2,6-Dichloro-3-methyl-4-octoxy-2',6'-difluoroazobenzene, 2,6-Dichloro-3,5-dimethyl-4-octoxy-2',6'-difluoroazobenzene, 2,6-Dichloro-2',6'-difluoro-4'-octoxyazobenzene, 2,6-Dichloro-3-methyl-2',6'-difluoro Ro-4'-octoxyazobenzene, 2,6-dichloro-4-hexoxy-2',6'-difluoroazobenzene, 2,6-dichloro-4-heptoxy-2',6'-difluoroazobenzene, 2,6-dibromo-4-octoxy-2',6'-difluoroazobenzene, 2,6-dibromo-4-octoxy-2',6'-dichloroazobenzene, 4-butoxy-2,6-dichloro-3,5-dimethyl-2 ',6'-difluoroazobenzene, 2,6-dichloro-3,5-dimethyl-4-pentoxy-2',6'-difluoroazobenzene, 2,6-dichloro-4-hexoxy-3,5-dimethyl-2',6'-difluoroazobenzene, 2,6-dichloro-3-methyl-2',6'-difluoro-4'-methoxyazobenzene, 2,6-dichloro-3-methyl-4'-ethoxy-2',6'-difluoroazo Benzene, 2,6-dichloro-3-methyl-2',6'-difluoro-4'-propoxyazobenzene, 2,6-dichloro-3-methyl-4'-butoxy-2',6'-difluoroazobenzene, 2,6-dichloro-3-methyl-2',6'-difluoro-4'-pentoxyazobenzene, 2-chloro-6-methyl-2'-chloro-4'-methoxy-6'-methyl-3'-isopropylazobenzene, etc.

[0018] As described above, the azobenzene derivative has the structure represented by formula (1) above, which gives it the property of melting when irradiated with visible light. That is, an azobenzene derivative having the structure represented by formula (1) above can undergo a phase transition from the solid phase to the liquid phase by irradiation with visible light. This is because the azobenzene derivative undergoes a photoisomerization reaction upon irradiation with visible light, for example, photoisomerizing from the trans isomer to the cis isomer. Furthermore, an azobenzene derivative having the structure represented by formula (1) above is a photosensitive azobenzene derivative. It is preferable that an azobenzene derivative having the structure represented by formula (1) above undergoes a phase transition from the solid phase to the liquid phase by irradiation with visible light with a wavelength of 500 to 650 nm (preferably 520 to 600 nm). This wavelength of visible light can be adjusted by changing R1 to R3 and X1 to X4 in formula (1) above. The range of wavelengths used for the phase transition can also be predicted from the absorption spectrum obtained by measuring the azobenzene derivative by ultraviolet-visible spectroscopy.

[0019] Furthermore, it is preferable that the azobenzene derivative having the structure represented by formula (1) above undergoes a phase transition from the liquid phase to the solid phase by irradiation with visible light. This is because the azobenzene derivative undergoes a photoisomerization reaction upon irradiation with visible light, for example, photoisomerizing from the cis isomer to the trans isomer. For example, it is preferable that the azobenzene derivative having the structure represented by formula (1) above undergoes a phase transition from the liquid phase to the solid phase by irradiation with visible light with a wavelength of 400 to 500 nm (preferably 420 to 480 nm). This wavelength of visible light can be adjusted by changing R1 to R3 and X1 to X4 in formula (1) above. The range of wavelengths used for the phase transition can also be predicted from the absorption spectrum obtained by measuring the azobenzene derivative by ultraviolet-visible spectroscopy.

[0020] If an azobenzene derivative undergoes a phase transition from a solid phase to a liquid phase when irradiated with visible light at a wavelength of 500-650 nm, and also undergoes a phase transition from a liquid phase to a solid phase when irradiated with visible light at a wavelength of 400-500 nm, then irradiating the azobenzene derivative with light containing wavelengths of 400-650 nm will simultaneously cause photoisomerization from the trans isomer to the cis isomer and from the cis isomer to the trans isomer. However, in this case, the phase transition of the azobenzene derivative can be controlled by adjusting the intensity distribution of wavelengths in the 400-650 nm range. For example, if sunlight, which has a stronger intensity at wavelengths of 500-650 nm than at wavelengths of 400-500 nm, is irradiated onto the azobenzene derivative, a phase transition from the solid phase to the liquid phase will occur. Conversely, by irradiating an azobenzene derivative with light whose intensity at wavelengths of 400-500 nm is stronger than that at wavelengths of 500-650 nm, a phase transition from the liquid phase to the solid phase can be induced.

[0021] It is preferable that an azobenzene derivative having the structure represented by formula (1) above can undergo a phase transition between a solid phase and a liquid phase by irradiation with visible light. That is, it is preferable that the solid phase and liquid phase of the azobenzene derivative undergo a reversible phase change by irradiation with visible light. Having such properties makes it possible to contribute to energy saving and resource saving in photothermal energy storage materials and adhesives containing azobenzene derivatives.

[0022] Here, "crystalline phase" refers to the solid state in which the molecules of the azobenzene derivative are arranged regularly, while "liquid phase" refers to the fluid state in which the molecules of the azobenzene derivative are arranged irregularly. Furthermore, "reversible" means that it is possible to return a substance that has been in a liquid state back to its original solid state.

[0023] Azobenzene derivatives having the structure represented by formula (1) above can be incorporated into photosensitive materials, thin films, photoresist materials, printing plate materials, photothermal energy storage materials, adhesives, optical elements, or actuator materials that can be patterned by light irradiation, and the property of the azobenzene derivative to melt with visible light can be utilized. In other words, the photovoltaic thermal storage material is a photovoltaic thermal storage material containing the azobenzene derivative of the present invention. Furthermore, the adhesive is an adhesive containing the azobenzene derivative of the present invention. Furthermore, the optical element is an optical element containing the azobenzene derivative of the present invention. Examples of optical elements include light-controllable TFT elements or light-controllable liquid crystal displays. In addition, the actuator material is an actuator material containing the azobenzene derivative of the present invention.

[0024] The azobenzene derivative having the structure represented by formula (1) above preferably has an isomerization reaction enthalpy (ΔHisom) measured by differential scanning calorimetry (DSC) of -70.0 to -30.0 J / g, and more preferably -60.0 to -40.0 J / g. Furthermore, the crystallization enthalpy (ΔHcryst) measured by differential scanning calorimetry (DSC) is preferably -80.0 to -40.0 J / g, and more preferably -70.0 to -50.0 J / g. By being within these ranges, for example, in photothermal energy storage materials, heat storage and heat dissipation can be performed effectively. ΔHisom and ΔHcryst can be adjusted by changing R1 to R3 and X1 to X4.

[0025] The azobenzene derivative having the structure represented by formula (1) above preferably has a lifetime at 30°C of 10.0 days or more, more preferably 31.0 days or more, even more preferably 40.0 days or more, and particularly preferably 50.0 days or more, as calculated by the liquid phase stability calculation method described later. The upper limit is not particularly limited, but may be 200.0 days or less, 150.0 days or less, or 120.0 days or less. For example, 10.0 to 200.0 days, 31.0 to 200.0 days, 40.0 to 150.0 days, and 50.0 to 120.0 days are possible. Within the above range, for example, in a photothermal energy storage material, the stored state of light energy can be maintained for a long period of time. The lifetime at 30 degrees Celsius can be adjusted by changing R1~R3 ​​and X1~X4.

[0026] Since the hardness, viscosity, and fluidity of a compound differ between its crystalline and liquid phases, the azobenzene derivative according to the present invention can be applied to materials in which the hardness, viscosity, fluidity, and diffusion coefficient can be freely controlled by light. Furthermore, since the refractive index of a compound differs between the crystalline and liquid phases, the azobenzene derivative according to the present invention can be applied to materials whose refractive index can be freely controlled by light. Furthermore, since the birefringence of the compound differs between the crystalline and liquid phases, the azobenzene derivative according to the present invention can be applied to materials in which birefringence can be freely controlled by light. Also, since the scattering intensity of light differs between the crystalline and liquid phases, it can be applied to materials in which the scattering intensity can be freely controlled by light. Furthermore, since the above-mentioned changes in the properties of the azobenzene derivative according to the present invention are performed using light, the properties can be changed at any location. That is, hardness, viscosity, fluidity, diffusion coefficient, refractive index, birefringence, and scattering intensity can be patterned. Furthermore, by utilizing the difference in birefringence between the crystalline and liquid phases and combining it with polarizing plates, a display element or recording element can be created. Specifically, by sandwiching the azobenzene derivative according to the present invention between polarizing plates orthogonal to each other, light is transmitted in the crystalline state which exhibits birefringence, but not in the liquid state which does not exhibit birefringence. By patterning this, a display or recording element can be created. Furthermore, by irradiating the azobenzene derivative according to the present invention with patterned light and patterning the crystalline phase and liquid phase, the liquid phase can be removed by utilizing the difference in fluidity or diffusion coefficient, thereby creating a pattern. This can then be used to create a resist pattern.

[0027] A method for producing an azobenzene derivative having the structure represented by formula (1) above will be described. The method for producing an azobenzene derivative having the structure represented by formula (1) above is not particularly limited as long as an azobenzene derivative having the desired structure can be produced, but the following method is preferred. By using the following production method, an azobenzene derivative having the structure represented by formula (1) above can be suitably produced. That is, preferably, step (A) involves contacting at least one azobenzene derivative selected from the group consisting of an azobenzene derivative represented by the following formula (2-1), an azobenzene derivative represented by the following formula (2-2), and an azobenzene derivative represented by the following formula (2-3) with a halogenating agent in the presence of a palladium compound to obtain an azobenzene derivative represented by the following formula (3), The method for producing an azobenzene derivative comprises, in this order, step (B) deprotecting the acetoxy group of the azobenzene derivative represented by the following formula (3) obtained in step (A) to obtain the azobenzene derivative represented by the above formula (1). [ka] [ka] [ka] (In formulas (2-1), (2-2), and (2-3), R'1 represents an acetoxy group, R2 independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms (preferably 1 to 2, preferably 3 to 4, more preferably 1), R3 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms (preferably 1 to 2, preferably 3 to 4, more preferably 1), or an alkoxy group having 1 to 4 carbon atoms (preferably 1 to 2, preferably 3 to 4, more preferably 1), and X1 to X4 independently represent a halogen atom or an alkyl group having 1 to 2 carbon atoms.) [ka] (In formula (3), R'1 represents an acetoxy group, R2 independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms (preferably 1 to 2, preferably 3 to 4, more preferably 1), R3 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms (preferably 1 to 2, preferably 3 to 4, more preferably 1), or an alkoxy group having 1 to 4 carbon atoms (preferably 1 to 2, preferably 3 to 4, more preferably 1), and X1 to X4 independently represent a halogen atom or an alkyl group having 1 to 2 carbon atoms, with one or more of X1 to X4 representing a halogen atom.)

[0028] The following describes process (A). Step (A) is a step in which an azobenzene derivative intermediate represented by formulas (2-1) to (2-3) is contacted with a halogenating agent in the presence of a palladium compound to obtain an azobenzene derivative intermediate represented by formula (3). That is, it is a step in which an azobenzene derivative intermediate having an acetoxy group represented by formulas (2-1) to (2-3) is halogenated to obtain an azobenzene derivative intermediate represented by formula (3). By having such a step (A) in the method for producing an azobenzene derivative, an azobenzene derivative intermediate represented by formula (3) can be obtained. Here, it is preferable that in formulas (2-1), (2-2), and (2-3), X1 to X4 each independently represent a halogen atom. Furthermore, in formula (3), it is preferable that X1 to X4 each independently represent a halogen atom, and that X1 to X4 represent a combination of two or more halogen atoms.

[0029] Palladium compounds are used as catalysts for halogenation reactions. Palladium compounds are not particularly limited as long as they can be used as catalysts for halogenation reactions, but examples include palladium salts such as palladium chloride, palladium acetate, palladium trifluoroacetate, and palladium nitrate, complex compounds such as π-allyl palladium chloride dimer, palladium acetylacetonate, tris(dibenzylideneacetone)dipalladium, bis(dibenzylideneacetone)palladium, dichlorobis(acetonitrile)palladium, and dichlorobis(benzonitrile)palladium, as well as palladium having tertiary phosphine ligands such as dichlorobis(triphenylphosphine)palladium, tetrakis(triphenylphosphine)palladium(0), dichloro[1,1'-bis(diphenylphosphino)ferrocene]palladium, bis(tri-tert-butylphosphine)palladium, bis(tricyclohexylphosphine)palladium, and dichlorobis(tricyclohexylphosphine)palladium. Among these, tetrakis(triphenylphosphine)palladium(0) is preferred. Palladium compounds may be used alone or in combination of two or more. The amount of palladium compound added is not particularly limited, but is preferably 0.1 to 5.0 mol, more preferably 0.5 to 4.0 mol, and particularly preferably 1.5 to 3.5 mol, per 100.0 mol of the azobenzene derivative represented by formulas (2-1) to (2-3).

[0030] Furthermore, palladium compounds may be prepared in the reaction system by adding ligands such as tertiary phosphines to palladium salts or complex compounds. Tertiary phosphines that can be used in this case include triphenylphosphine, trimethylphosphine, tributylphosphine, tri(tert-butyl)phosphine, tricyclohexylphosphine, tert-butyldiphenylphosphine, 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene, 2-(diphenylphosphino)-2'-(N,N-dimethylamino)biphenyl, 2-(di-tert-butylphosphino)biphenyl, 2-(dicyclohexylphosphino)biphenyl, and bis(diphenyl Examples include nylphosphino)methane, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,1'-bis(diphenylphosphino)ferrocene, tri(2-furyl)phosphine, tri(o-tolyl)phosphine, tris(2,5-xylyl)phosphine, (±)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, and 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl.

[0031] Examples of halogenating agents that can be used include chlorinating agents such as chlorine, N-chlorosuccinimide, N-chlorophthalimide, 1,3-dichloro-5,5-dimethylhydantoin (DCDMH), and trichloroisocyanuric acid; brominating agents such as bromine, N-bromosuccinimide, N-bromophthalimide, 1,3-dibromo-5,5-dimethylhydantoin, and tribromoisocyanuric acid; and iodinating agents such as iodine, N-iodosuccinimide, N-iodophthalimide, 1,3-diiodo-5,5-dimethylhydantoin, and triiodoisocyanuric acid. Among these, trichloroisocyanuric acid is preferred as a chlorinating agent, tribromoisocyanuric acid as a brominating agent, and triiodoisocyanuric acid as an iodinating agent. Halogenating agents may be used alone or in combination of two or more. The amount of halogenating agent added is not particularly limited, but is preferably 50.0 to 250.0 mol, more preferably 50.0 to 200.0 mol, even more preferably 50.0 to 150.0 mol, particularly preferably 65.0 to 135.0 mol, and especially preferably 80.0 to 120.0 mol, per 100.0 mol of the azobenzene derivative represented by formulas (2-1) to (2-3).

[0032] In addition, oxidizing agents may be used as needed. Examples of oxidizing agents include persulfates and their salts, such as ammonium, sodium, potassium, cesium, and alkylammonium salts, inorganic peroxodisulfates, and peroxides such as benzoyl peroxide. Among these, potassium peroxodisulfate is preferred. Oxidizing agents may be used alone or in combination of two or more. The amount of oxidizing agent added is not particularly limited, but is preferably 70.0 to 170.0 mol, more preferably 85.0 to 155.0 mol, and particularly preferably 100.0 to 140.0 mol, per 100.0 mol of the azobenzene derivative represented by formulas (2-1) to (2-3).

[0033] The reaction solvent is not particularly limited, but examples include carbon tetrachloride, 1,1,2,2-tetrachloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, chloroform, and chlorobenzene. Among these, 1,1,2,2-tetrachloroethane is preferred. The reaction solvent may be used alone or in combination of two or more. The amount of reaction solvent added is not particularly limited, but it is preferable that the concentration of the azobenzene derivative represented by formulas (2-1) to (2-3) in the reaction solution be 0.1 to 2.0 mol / L, more preferably 0.2 to 1.5 mol / L, and particularly preferably 0.4 to 1.2 mol / L.

[0034] Other reaction conditions are not particularly limited, but the reaction temperature is preferably 90 to 130°C, and more preferably 100 to 120°C. The reaction time is preferably 0.1 to 10.0 hours, more preferably 0.5 to 5.0 hours, and even more preferably 0.5 to 2.0 hours.

[0035] Azobenzene derivatives represented by formulas (2-1) to (2-3) above can generally be synthesized by reductively dimerizing a precursor nitro compound. Alternatively, they can be synthesized by oxidatively dimerizing a precursor amino compound. Alternatively, they can be synthesized by a diazo coupling reaction between a precursor amino compound and a phenol derivative. Alternatively, they can be synthesized by a condensation reaction between a precursor nitroso compound and an amino compound.

[0036] The following describes process (B). Step (B) is a step in which the acetoxy group of the azobenzene derivative intermediate represented by formula (3) obtained in step (A) is deprotected to obtain the azobenzene derivative represented by formula (1). By having such a step (B), the method for producing the azobenzene derivative can be obtained.

[0037] The reaction conditions are not particularly limited, as long as the acetoxy group of the azobenzene derivative represented by formula (3) can be deprotected to obtain the azobenzene derivative represented by formula (1). For example, to hydrolyze an acetoxy group for the purpose of deprotecting it, an acid or base can be used to hydrolyze the acetoxy group. Using a base is more preferable. Examples of bases include sodium hydride, sodium hydroxide, potassium hydroxide, and lithium hydroxide, with sodium hydride being preferable. Examples of acids include hydrogen chloride, sulfuric acid, acetic acid, and formic acid. The amount of acid or base added is not particularly limited, but is preferably 100.0 to 600.0 mol, more preferably 200.0 to 500.0 mol, and especially preferably 350.0 to 450.0 mol, per 100.0 mol of the azobenzene derivative represented by formula (3). Water may be added for hydrolysis. The type of water is not particularly limited; for example, distilled water can be used. Preferably, the amount of water added is equal to the amount of the acid or base mentioned above.

[0038] It is preferable to use an alkyl halide having 1 to 18 carbon atoms. More preferably, the number of carbon atoms is 3 to 18, even more preferably 6 to 18, even more preferably 6 to 16, particularly preferably 6 to 14, and especially preferably 6 to 12. The alkyl halide is not particularly limited, but it is preferable to use at least one selected from the group consisting of alkyl chloride, alkyl bromide, and alkyl iodide. More preferably, it is an alkyl bromide. Examples of such alkyl halides include alkyl chlorides such as chloropropane, chlorobutane, chloropentane, chlorohexane, chloroheptane, chlorooctane, chlorononane, chlorodecane, chloroundecane, and chlorododecane; alkyl bromides such as bromopropane, bromobutane, bromopentane, bromohexane, bromoheptane, bromooctane, bromononane, bromodecane, bromoundecane, and bromododecane; and alkyl iodides such as iodopropane, iodobutane, iodopentane, iodohexane, iodoheptane, iodooctane, iodononane, iododecane, iodoundecane, and iodododecane. The amount of alkyl halide added is not particularly limited, but it is preferably 100.0 to 300.0 mol, more preferably 150.0 to 250.0 mol, and especially preferably 175.0 to 225.0 mol, per 100.0 mol of the azobenzene derivative represented by formula (3). Furthermore, methylating agents such as methyl p-toluenesulfonate and ethylating agents such as ethyl p-toluenesulfonate may be used. The amount of methylating agent and ethylating agent added can be the same as that for alkyl halides.

[0039] It is preferable to use a crown ether as a catalyst. By using a crown ether, the solubility of the intermediate salt can be increased by trapping sodium. The crown ether is not particularly limited, but examples include 18-crown-6, 15-crown-5, and 12-crown-4, with 18-crown-6 being preferred. The amount of crown ether added is not particularly limited, but is preferably 0.1 to 5.0 mol, more preferably 0.5 to 4.0 mol, and especially preferably 1.5 to 3.5 mol, per 100.0 mol of the azobenzene derivative represented by formula (3).

[0040] The reaction solvent is not particularly limited, but examples include 1,4-dioxane, tetrahydrofuran (THF), and N,N-dimethylformamide. Among these, tetrahydrofuran is preferred. The reaction solvent may be used alone or in combination of two or more. The amount of reaction solvent added is not particularly limited, but it is preferably an amount such that the concentration of the azobenzene derivative represented by formula (3) in the reaction solution is 0.1 to 2.0 mol / L, more preferably an amount such that it is 0.1 to 1.0 mol / L, and particularly preferably an amount such that it is 0.1 to 0.5 mol / L.

[0041] Other reaction conditions are not particularly limited, but the reaction temperature is preferably 50 to 80°C, more preferably 60 to 70°C. It is especially preferable that the reaction solvent is refluxed at this temperature. The reaction time is preferably 1.0 to 40.0 hours, more preferably 5.0 to 30.0 hours, and even more preferably 12.0 to 24.0 hours. [Examples]

[0042] The present invention will be further described below based on examples, but the present invention is not limited to such representative examples.

[0043] <Synthesis and Characterization> The following compounds were synthesized, and their thermophysical properties and photoresponsiveness were evaluated. A summary of the compounds examined is provided below.

[0044] <Reagents and equipment used in the experiment> (Reagents used in the experiment) Commercially available reagents and solvents were used directly for synthesis and property evaluation. Silica gel 100 (manufactured by Kanto Chemical Co., Ltd.) was used for column chromatography. (NMR spectrum) The NMR (nuclear magnetic resonance) spectrum was measured using the NMR analyzer "Avance 400" (Bruker).

[0045] (Analysis of the thermal behavior of synthesized compounds) The thermal behavior of the synthesized compounds was analyzed in the dark using a differential scanning calorimeter (DSC) (DSC6100, manufactured by SII Nanotechnology). The phase transition temperature of each compound is indicated by a symbol. For example, "Cr 43 Iso, Iso 30 Cr" means that the crystalline (Cr) melted at 43°C during heating and changed to a liquid (Iso), and the liquid solidified at 30°C during cooling. Also, "Cr 43 Iso" means that the crystalline (Cr) melted at 43°C during heating and changed to a liquid (Iso). Note that X indicates an unconfirmed phase.

[0046] (Photoirradiation experiments for each compound) Light irradiation experiments for each compound were performed using samples prepared by encapsulating the compound crystals in glass sandwich cells. Light irradiation was performed at room temperature under observation using a polarizing optical microscope. The polarizing optical microscope used was a "BX51" microscope (manufactured by Olympus Corporation). A high-pressure mercury lamp was used as the light source for light irradiation. Light was passed through a filter and irradiated at an arbitrary wavelength. In observation with a polarizing optical microscope, when the sample was observed with the transmission axes of the polarizer and analyzer of the polarizing microscope orthogonal to each other (orthogonal nicols), it was judged that a phase transition from the crystalline phase to the isotropic phase had been induced when the bright field disappeared due to birefringence of the crystal and became a dark field. Conversely, it was judged that a phase transition from the isotropic phase to the crystalline phase had been induced when the field changed from dark field to bright field. Furthermore, the induction of phase transitions from the solid phase to the liquid phase and from the liquid phase to the solid phase was judged by visual inspection.

[0047] (Stability of the liquid phase) The stability of the liquid phase was calculated as follows: The phase transition from solid to liquid is induced by photoisomerization from the trans isomer to the cis isomer of an azobenzene derivative. Conversely, the phase transition from liquid to solid is induced by photoisomerization or thermal isomerization from the cis isomer to the trans isomer of an azobenzene derivative. Here, the stability of the liquid phase can be defined by the thermal stability of the cis isomer. Specifically, the stability of the liquid phase was calculated by determining the lifetime at 30°C from the rate constant of thermal isomerization of the cis isomer of the azobenzene derivative in the dark at 30°C. Here, the lifetime is defined as the reciprocal (1 / k) of the reaction rate constant (k) of the thermal isomerization reaction. The lifetime of the azobenzene derivative of this application at 30°C is long, and direct measurement is experimentally difficult. Therefore, k at 30°C was calculated using measurements at multiple temperatures in accelerated high-temperature tests and the Arrhenius equation. Specifically, the rate constant (k) of thermal isomerization was measured at different temperatures, and the reciprocal of the absolute temperature (1 / T) was plotted on the x-axis, with the natural logarithm of the reaction rate constant (k) (ln k) on the y-axis. k at 30°C was calculated using this plot and the Arrhenius equation. The Arrhenius equation is expressed by the following equation (4). ln k = A exp(-Ea / RT) (4) In equation (4), A is the frequency factor, Ea is the activation energy, R is the gas constant, and T is the absolute temperature.

[0048] Furthermore, the rate constant of thermal isomerization was measured as follows: azobenzene derivative in 1,1,2,2-tetrachloroethane (TCE) solution (5x10 -5 The sample (mol / l) was irradiated with 365 nm light for 10 minutes, and then held at a predetermined temperature using a UV-Vis spectrophotometer "V-780" (manufactured by JASCO) and its attached constant temperature cell holder "ETCR-762" (manufactured by JASCO). By observing the time evolution of the absorption spectrum of this sample, the rate constant (k) of thermal isomerization at the predetermined temperature was obtained.

[0049] <Example 1-1> (Synthesis of compound C2-A1-OAc (intermediate 1-1)) 16 mL of distilled water and 4 mL of concentrated hydrochloric acid were added to 1.29 g of 2,6-difluoroaniline (10 mmol). While stirring at 0°C, a solution prepared by dissolving 0.83 g of sodium nitrite (12 mmol) in 5 mL of distilled water was added. The resulting solution was then added to 20 mL of an aqueous solution of 0.94 g of phenol (10 mmol) and 4.7 g of sodium hydroxide, and stirred for 15 minutes. The resulting solution was cooled, acidified with hydrochloric acid, and then extracted with ethyl acetate. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was diluted with 50 mL of anhydrous dichloromethane, and 12.1 g (12 mmol) of triethylamine (TEA) was added. A mixture of 0.94 g (12 mmol) of acetyl chloride (AcCl) dissolved in 10 mL of dichloromethane (DCM) was added dropwise while stirring at 0°C under nitrogen. The resulting solution was left to stand for 1 hour and then extracted with water. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was purified by silica gel column chromatography to obtain intermediate 1-1 shown below (orange solid, 1.33 g, yield: 48%). [ka]

[0050] Intermediate 1-1 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.33 (s, 3H), 7.04 (t, J=8.5 Hz, 2H), 7.26 (dd, J1= 8.7Hz, J2=1.9Hz, 2H), 7.28-7.35 (m, 1H), 7.97 (dd, J1=8.9Hz, J2=2.0Hz, 2H)

[0051] <Example 1-2> (Synthesis of compound C2-A1A-OAc (intermediate 1-2)) 5 mL of 1,1,2,2-tetrachloroethane (TCE), trichloroisocyanuric acid (TCCA, 0.93 g, 4 mmol), potassium peroxodisulfate (1.3 g, 4.8 mmol), and tetrakis(triphenylphosphine)palladium (0) (0.12 g, 0.1 mmol) were added to compound C2-A1-OAc (intermediate 1-1, 1.1 g, 4 mmol), and the mixture was stirred at 110°C for 2 hours. The mixture was then filtered, and the solvent was removed from the filtrate under reduced pressure. The resulting solid was purified by silica gel column chromatography to obtain intermediate 1-2 shown below (red solid, 1.1 g, yield: 80.4%). [ka]

[0052] Intermediate 1-2 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.29 (s, 3H), 7.00-7.11 (m, 1H), 7.07 (t, J=8.6 Hz, 2H), 7.27-7.47 (m, 1H)

[0053] <Examples 1-3> (Synthesis of compound C2-A1A-OC8 (azobenzene derivative 1)) 5 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 160 mg, 4 mmol) were added to compound C2-A1A-OAc (intermediate 1-2, 0.34 g, 1 mmol), and the mixture was stirred at room temperature. 5 mL of a mixture of THF and 72 mg of distilled water was added dropwise to the reaction mixture, and the mixture was stirred at room temperature for 1 hour. A catalytic amount (0.05 mmol) of crown ether 18-crown-6 and 1-bromooctane (0.38 g, 2 mmol) were added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain azobenzene derivative 1 (orange solid, 0.41 g, yield: 100%) as shown below. [ka]

[0054] Azobenzene derivative 1 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.88-0.91 (m, 3H), 1.30-1.45 (m, 2H), 1.49-1.51 (m, 2H), 1.76-1.83 (m, 2H), 3.99 (t, J= 6.5 Hz, 2H), 7.23 (dd, J1= 4.8Hz, J2=2.1Hz, 2H), 7.90 (dd, J1= 6.9Hz, J2=1.5Hz 2H), 7.95 (dd, J1= 4.8Hz, J2=2.1Hz, 2H) 13C NMR (100 MHz, CDCl3): 14.12, 22.67, 25.90, 28.95, 29.22, 29.28, 31.81, 68.98, 76.72, 77.04, 77.24, 77.35, 77.52, 112.52, 112.55, 112.56, 112.71, 112.73, 112.76, 115 / 65, 129.06, 130.91, 131.01, 131.14, 131.24, 131.34, 141.64, 154.42, 154.46, 157.01, 157.05, 159.24

[0055] <Examples 1-4> (Thermal phase change of compound C2-A1A-OC8 (azobenzene derivative 1) by DSC measurement) A chloroform solution of compound C2-A1A-OC8 was irradiated with ultraviolet light (365 nm) for 15 minutes to induce trans-cis isomerization. The solvent was removed from the mixture under reduced pressure, and the isomer mixture was separated by silica gel column chromatography to obtain cis-type azobenzene derivative 1 and trans-type azobenzene derivative 1. The thermal phase transition temperatures of both isomers of compound C2-A1-OC8 were measured using a differential scanning calorimeter, and the phase change occurred at the following temperatures. Trans Cr 43 Iso, Iso 30 Cr Cis Cr 48 Iso

[0056] <Examples 1-5> (Measuring isomerization reaction enthalpy and crystallization enthalpy of compound C2-A1A-OC8 (azobenzene derivative 1) by DSC measurement) The energy released during thermally induced cis-trans isomerization (ΔHisom) of compound C2-A1A-OC8 and subsequent recrystallization (ΔHcryst) of the trans compound C2-A1A-OC8 was measured using differential scanning calorimeter, yielding the following results. ΔH isom = -56.1 J / g (-23.3 kJ / mol), ΔH cryst = -66.1 J / g (-27.4 kJ / mol)

[0057] <Examples 1-6> (Photoirradiation experiment of compound C2-A1A-OC8 (azobenzene derivative 1)) The crystalline-isotropic phase transition of the compound C2-A1A-OC8 was observed in a glass sandwich cell at 23°C using a polarized light microscope. The results are shown in Figure 1. In Figure 1, (a) is a polarized light microscope image showing the crystalline phase at 23°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 23°C, and (c) is a polarized light microscope image showing the state after irradiation with green light followed by irradiation with blue light (450 nm) at 23°C. As is clear from Figure 1, irradiation with green light caused a phase transition from the crystalline phase to the isotropic phase, and a change from bright-field to dark-field observation was observed under orthogonal nicols (see (b)). Irradiation with green light caused the birefringence of the crystal to disappear, confirming that it had melted from a crystal to a liquid. Furthermore, when the isotropic phase (liquid phase) was irradiated with blue light, the birefringence of the crystal reappeared. From this, it was confirmed that a phase transition from the isotropic phase to the crystalline phase occurred and a crystal was formed (see (c)).

[0058] <Examples 1-7> (Calculation of the liquid phase stability of compound C2-A1A-OC8 (azobenzene derivative 1)) The rate constant (k) for thermal isomerization was measured at 50°C, 60°C, 70°C, 80°C, and 90°C, respectively. Using these values ​​and an Arrhenius plot, the lifetime at 30°C was calculated to be 60.0 days.

[0059] <Example 2-1> (Synthesis of compound C2-A4-OAc (intermediate 2-1)) 16 mL of distilled water and 4 mL of concentrated hydrochloric acid were added to 1.29 g of 2,6-difluoroaniline (10 mmol). While stirring at 0°C, a solution prepared by dissolving 0.83 g of sodium nitrite (12 mmol) in 5 mL of distilled water was added. The resulting solution was then added to 20 mL of an aqueous solution of 1.08 g of o-cresol (10 mmol) and 4.7 g of sodium hydroxide, and stirred for 15 minutes. The resulting solution was cooled, acidified with hydrochloric acid, and then extracted with ethyl acetate. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was diluted with 50 mL of anhydrous dichloromethane, and 12.1 g (12 mmol) of triethylamine (TEA) was added. While stirring at 0°C under nitrogen, a mixture of 0.94 g (12 mmol) of acetyl chloride (AcCl) dissolved in 10 mL of dichloromethane (DCM) was added dropwise. The resulting solution was allowed to stand for 1 hour and then extracted with water. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was purified by silica gel column chromatography to obtain intermediate 2-1 shown below (orange solid, 2.47 g, yield: 85%). [ka]

[0060] Intermediate 2-1 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.28 (s, 3H), 2.35 (s, 3H), 7.03 (t, J= 8.6 Hz, 2H), 7.27-7.34 (m, 1H), 7.80-7.83 (m, 2H)

[0061] <Example 2-2> (Synthesis of compound C2-A4A-OAc (intermediate 2-2)) 5 mL of 1,1,2,2 - tetrachloroethane (TCE), trichloroisocyanuric acid (TCCA, 0.70 g, 3 mmol), potassium peroxydisulfate (0.98 g, 3.6 mmol) and tetrakis(triphenylphosphine)palladium(0) (0.90 g, 0.075 mmol) were added to compound C2 - A1 - OAc (intermediate 2 - 1, 0.87 g, 3 mmol), and the mixture was stirred at 110 °C for 2 h. Then, the mixture was filtered and the solvent was distilled off under reduced pressure from the filtrate. The obtained solid was purified by silica gel column chromatography to obtain intermediate 2 - 2 shown below (red solid, 0.97 g, yield: 89.9%). [Chemical Structure]

[0062] Intermediate 2 - 2 was 1 analyzed by 1H NMR to determine its structure. 1H NMR (400 MHz, CDCl3): 2.21 (s, 3H), 2.35 (s, 3H), 7.04 (t, J = 8.6 Hz, 2H), 7.31 (s, 1H), 7.32 - 7.46 (m, 1H)

[0063] <Example 2 - 3> (Synthesis of compound C2 - A4A - OC8 (azobenzene derivative 2)) 5 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 160 mg, 4 mmol) were added to compound C2 - A4A - OAc (intermediate 1 - 2, 0.36 g, 1 mmol), and the mixture was stirred at room temperature. A mixture of 5 mL of THF and 72 mg of distilled water was added dropwise to the reaction mixture, and then the mixture was stirred at room temperature for 1 h. A catalytic amount (0.05 mmol) of crown ether 18 - crown - 6 and 1 - bromooctane (0.38 g, 2 mmol) were added to the reaction mixture, and the mixture was stirred at 66 °C for 22 h. The solvent was distilled off under reduced pressure from the mixture, and the obtained solid was purified by silica gel column chromatography to obtain azobenzene derivative 2 shown below (orange solid, 0.34 g, yield: 79.5%). [ka]

[0064] Azobenzene derivative 2 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.88-0.91 (m, 3H), 1.30-1.56 (m, 10H), 1.80-1.87 (m, 2H), 4.00 (t, J= 7.8 Hz, 2H), 6.88 (s, 1H), 7.07 (t, J= 8.6 Hz, 2H) 7.31-7.41 (m, 1H) 13C NMR (100 MHz, CDCl3): 12.79, 1423, 22.68, 26.04, 29.24, 29.29, 31.82, 69.09, 115.58, 112.51, 112.53, 112.55, 112.70, 112.72, 112.74, 123.68, 125.83, 129.76, 130.92, 131.03, 131.13, 131.24, 141.97, 154.39, 154.44, 156.99, 157.03, 157.41

[0065] <Example 2-4> (Thermal phase change of compound C2-A4A-OC8 (azobenzene derivative 2) by DSC measurement) A chloroform solution of compound C2-A4A-OC8 was irradiated with ultraviolet light (365 nm) for 15 minutes to induce trans-cis isomerization. The solvent was removed from the mixture under reduced pressure, and the isomer mixture was separated by silica gel column chromatography to obtain cis-type azobenzene derivative 2 and trans-type azobenzene derivative 2. The thermal phase transition temperatures of both isomers of compound C2-A4A-OC8 were measured using a differential scanning calorimeter, and the phase change occurred at the following temperatures. Trans Cr1 58 X, X 60 Iso, Iso 42 X, X 39 Cr1 Cis Cr 61 Iso

[0066] <Example 2-5> (Measuring isomerization reaction enthalpy and crystallization enthalpy of compound C2-A4A-OC8 (azobenzene derivative 2) by DSC measurement) The energy released during thermally induced cis-trans isomerization (ΔHisom) of compound C2-A4A-OC8 and subsequent recrystallization (ΔHcryst) of the trans compound C2-A4A-OC8 was measured using a differential scanning calorimeter, yielding the following results. ΔH isom = -47.7 J / g (-20.5 kJ / mol), ΔH cryst = -59.8 J / g (-25.7 kJ / mol)

[0067] <Example 2-6> (Photoirradiation experiment of compound C2-A4A-OC8 (azobenzene derivative 2)) The crystalline-isotropic phase transition of the crystalline compound C2-A4A-OC8 in a glass sandwich cell at 23°C was observed using a polarized light microscope. The results are shown in Figure 2. In Figure 2, (a) is a polarized light microscope image showing the crystalline phase at 23°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 23°C, and (c) is a polarized light microscope image showing the state after irradiation with green light followed by irradiation with blue light (450 nm) at 23°C. As is clear from Figure 2, irradiation with green light caused a phase transition from the crystalline phase to the isotropic phase, and a change from bright-field to dark-field observation was observed under orthogonal nicols (see (b)). Irradiation with green light caused the birefringence of the crystal to disappear, confirming that it had melted from a crystal to a liquid. Furthermore, when the isotropic phase (liquid phase) was irradiated with blue light, the birefringence of the crystal reappeared. From this, it was confirmed that a phase transition from the isotropic phase to the crystalline phase occurred and a crystal was formed (see (c)).

[0068] <Example 2-7> (Calculation of the liquid phase stability of compound C2-A4A-OC8 (azobenzene derivative 2)) The rate constant (k) for thermal isomerization was measured at 50°C, 60°C, 70°C, and 90°C, respectively. Using these values ​​and an Arrhenius plot, the lifetime at 30°C was calculated to be 70.5 days.

[0069] <Example 3-1> (Synthesis of compound prec-A5-OAc (intermediate 3-1)) 1.67 g (10 mmol) of 2,6-dimethyl-4-nitrophenol was dissolved in 50 mL of anhydrous dichloromethane, and 12.1 g (12 mmol) of triethylamine was added. Under nitrogen at 0°C with stirring, a mixture of 0.94 g (12 mmol) of acetyl chloride (AcCl) dissolved in 5 mL of dichloromethane was added dropwise. The resulting solution was allowed to stand for 4 hours and then extracted with water. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. The solvent was removed under reduced pressure to obtain intermediate 3-1 shown below (white solid, 2.1 g, yield: 100%). [ka]

[0070] Intermediate 3-1 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.24 (s, 6H), 2.39 (s, 3H), 7.96 (s, 2H)

[0071] <Example 3-2> (Synthesis of compound A5-OAc (intermediate 3-2)) To 2.1 g (10 mmol) of intermediate 3-1, 50 mL of ethanol (EtOH) and a catalytic amount of 10% palladium(0) carbon were added. The atmosphere over the mixture was then evacuated and replaced with nitrogen, and then again with hydrogen. After stirring at room temperature under a hydrogen atmosphere for 48 hours, the mixture was filtered using Celite. After evaporating the solvent from the filtrate under reduced pressure, the resulting solid was purified by silica gel column chromatography to obtain intermediate 3-2 shown below (white solid, 1.5 g, yield: 84.1%). [ka]

[0072] Intermediate 3-2 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.05 (s, 6H), 2.29 (s, 3H), 3.47 (broad, 2H), 6.36 (s, 2H)

[0073] <Example 3-3> (Synthesis of compound C2-A5-OAc (intermediate 3-3)) A solution of 2,6-difluoroaniline (0.52 g, 4 mmol) in 10 mL of dichloromethane (DCM) was mixed with 12.3 g of potassium peroxysulfate (oxone®, 20 mmol) and 20 mL of distilled water. After stirring for 2 hours, the organic layer was removed, washed with saturated brine, and dried on anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure to obtain 1,3-difluoro-2-nitrosobenzene as a gray powder, after which 5 mL of acetic acid and 0.72 g (4 mmol) of intermediate 3-2 (compound A5-OAc) were added. The mixture was stirred at room temperature for 24 hours, then diluted with distilled water, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was purified by silica gel column chromatography to obtain intermediate 3-3 shown below (orange solid, 1.0 g, yield: 90%). [ka]

[0074] Intermediate 3-3 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.25 (s, 6H), 2.37 (s, 3H), 7.03 (t, J= 8.4 Hz, 2H), 7.26-7.33 (m, 1H), 7.68 (s, 2H)

[0075] <Example 3-4> (Synthesis of compound C2-A5A-OAc (intermediate 3-4)) 5 mL of 1,1,2,2-tetrachloroethane (TCE), trichloroisocyanuric acid (TCCA, 0.47 g, 2 mmol), potassium peroxodisulfate (0.65 g, 2.4 mmol), and tetrakis(triphenylphosphine)palladium (0) (0.06 g, 0.05 mmol) were added to compound C2-A5-OAc (intermediate 3-3, 0.61 g, 2 mmol), and the mixture was stirred at 110°C for 2 hours. The mixture was then filtered, and the solvent was removed from the filtrate under reduced pressure. The resulting solid was purified by silica gel column chromatography to obtain intermediates 3-4 shown below (red solid, 0.68 g, yield: 90.1%). [ka]

[0076] Intermediate 3-4 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.25 (s, 6H), 2.39 (s, 3H), 7.09 (t, J= 8.6 Hz, 2H), 7.38-7.43 (m, 1H)

[0077] <Example 3-5> (Synthesis of compound C2-A5A-OC8 (azobenzene derivative 3)) 10 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 128 mg, 3.2 mmol) were added to compound C2-A4A-OAc (intermediate 3-4, 0.30 g, 0.8 mmol), and the mixture was stirred at room temperature. 5 mL of a mixture of THF and 58 mg of distilled water was added dropwise to the reaction mixture, and the mixture was stirred at room temperature for 1 hour. A catalytic amount (0.04 mmol) of crown ether 18-crown-6 and 1-bromooctane (0.30 g, 1.6 mmol) were added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain azobenzene derivative 3 (orange solid, 0.24 g, yield: 66.9%) as shown below. [ka]

[0078] Azobenzene derivative 3 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.88-0.92 (m, 3H), 1.31-1.36 (m, 8H), 1.49-1.51 (m, 2H), 1.78-1.85 (m, 2H) 2.36 (s, 6H), 3.73 (t, J= 6.6 Hz, 2H), 7.08 (t, J= 8.6 Hz, 2H), 7.36-7.41 (m, 1H) 13C NMR (100 MHz, CDCl3): 14.09, 14.48, 23.05, 26.48, 29.64, 29.87, 30.55, 32.22, 74.02, 112.93, 112.96, 112.97, 113.12, 113.14, 113.17, 124.61, 130.28, 131.24, 131.35, 131.92, 132.02, 132.13, 146.14, 154.85, 154.88, 156.54, 157.45, 157.49

[0079] <Example 3-6> (Thermal phase change of compound C2-A5A-OC8 (azobenzene derivative 3) by DSC measurement) A chloroform solution of compound C2-A5A-OC8 was irradiated with ultraviolet light (365 nm) for 15 minutes to induce trans-cis isomerization. The solvent was removed from the mixture under reduced pressure, and the isomer mixture was separated by silica gel column chromatography to obtain cis-type azobenzene derivative 3 and trans-type azobenzene derivative 3. The thermal phase transition temperatures of both isomers of compound C2-A5A-OC8 were measured using a differential scanning calorimeter, and the phase change occurred at the following temperatures. Trans Cr 62 Iso, Iso 10 Cr Cis Cr 51 Iso

[0080] <Example 3-7> (Measuring isomerization reaction enthalpy and crystallization enthalpy of compound C2-A5A-OC8 (azobenzene derivative 3) by DSC measurement) The energy released during thermally induced cis-trans isomerization (ΔHisom) of compound C2-A5A-OC8 and subsequent recrystallization (ΔHcryst) of the trans compound C2-A5A-OC8 was measured using differential scanning calorimeter, yielding the following results. ΔH isom = -51.0 J / g (-22.5 kJ / mol), ΔH cryst = -59.0 J / g (-26.1 kJ / mol)

[0081] <Example 3-8> (Photoirradiation experiment of compound C2-A5A-OC8 (azobenzene derivative 3)) The crystalline-isotropic phase transition of the crystalline compound C2-A5A-OC8 in a glass sandwich cell at 23°C was observed using a polarized light microscope. The results are shown in Figure 3. In Figure 3, (a) is a polarized light microscope image showing the crystalline phase at 23°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 23°C, and (c) is a polarized light microscope image showing the state after irradiation with green light followed by irradiation with blue light (450 nm) at 23°C. As is clear from Figure 3, irradiation with green light caused a phase transition from the crystalline phase to the isotropic phase, and a change from bright-field to dark-field observation was observed under orthogonal nicols (see (b)). Irradiation with green light caused the birefringence of the crystal to disappear, confirming that it had melted from a crystal to a liquid. Furthermore, when the isotropic phase (liquid phase) was irradiated with blue light, the birefringence of the crystal reappeared. From this, it was confirmed that a phase transition from the isotropic phase to the crystalline phase occurred and a crystal was formed (see (c)).

[0082] <Example 3-9> (Calculation of the liquid phase stability of compound C2-A5A-OC8 (azobenzene derivative 3)) The rate constant (k) for thermal isomerization was measured at 50°C, 60°C, 70°C, 80°C, and 90°C, respectively. Using these values ​​and an Arrhenius plot, the lifetime at 30°C was calculated to be 117.2 days.

[0083] <Example 4-1> (Synthesis of compound C3-A6-OAc (intermediate 4-1)) 0.93 g, 10 mmol of aniline was mixed with 16 mL of distilled water and 4 mL of concentrated hydrochloric acid. While stirring at 0°C, a solution prepared by dissolving 0.83 g, 12 mmol of sodium nitrite in 5 mL of distilled water was added. Then, 20 mL of an aqueous solution of 1.3 g, 10 mmol of 3,5-difluorophenol and 4.7 g of sodium hydroxide was added to the resulting solution, and the mixture was stirred for 15 minutes. The resulting solution was cooled, acidified with hydrochloric acid, and then extracted with ethyl acetate. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was diluted with 50 mL of anhydrous dichloromethane, and 12.1 g (12 mmol) of triethylamine (TEA) was added. While stirring at 0°C under nitrogen, a mixture of 0.94 g (12 mmol) of acetyl chloride (AcCl) dissolved in 10 mL of dichloromethane (DM) was added dropwise. The resulting solution was allowed to stand for 1 hour and then extracted with water. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was purified by silica gel column chromatography to obtain intermediate 4-1 shown below (orange solid, 2.22 g, yield: 80.2%). [ka]

[0084] Intermediate 4-1 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.31 (s, 3H), 7.03 (d, J= 1.9 Hz, 2H), 7.51-7.53 (m, 3H), 7.91-7.93 (m, 2H)

[0085] <Example 4-2> (Synthesis of compound C3-A6A-OAc (intermediate 4-2)) 5 mL of 1,1,2,2-tetrachloroethane (TCE), trichloroisocyanuric acid (TCCA, 1.16 g, 5 mmol), potassium peroxodisulfate (1.6 g, 6 mmol), and tetrakis(triphenylphosphine)palladium(0) (0.15 g, 0.12 mmol) were added to compound C2-A1-OAc (intermediate 4-1, 1.38 g, 5 mmol), and the mixture was stirred at 110°C for 2 hours. The mixture was then filtered, and the solvent was removed from the filtrate under reduced pressure. The resulting solid was purified by silica gel column chromatography to obtain intermediate 4-2 (red solid, 2.2 g, yield: 100%). [ka]

[0086] Intermediate 4-2 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 2.33 (s, 3H), 6.95 (dd, J1= 9.0 Hz, J2=2.9 Hz, 1H), 7.20 (t, J=8.4 Hz, 1H), 7.40 (s, 1H), 7.42 (s, 1H)

[0087] <Example 4-3> (Synthesis of compound C3-A6A-OC8 (azobenzene derivative 4)) 5 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 160 mg, 4 mmol) were added to compound C3-A6A-OAc (intermediate 4-2, 0.34 g, 1 mmol), and the mixture was stirred at room temperature. 5 mL of a mixture of THF and 72 mg of distilled water was added dropwise to the reaction mixture, and the mixture was stirred at room temperature for 1 hour. A catalytic amount (0.05 mmol) of crown ether 18-crown-6 and 1-bromooctane (0.38 g, 2 mmol) were added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain azobenzene derivative 4 (orange solid, 0.4 g, yield: 97.2%) as shown below. [ka]

[0088] Azobenzene derivative 4 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.88-0.91 (m, 3H), 1.22-1.45 (m, 10H), 1.77-1.85 (m, 2H), 4.00-4.08 (m, 2H), 6.37 (dd, J1=12Hz, J2=2.6 Hz, 1H), 6.60 (dd, J1=11.2 Hz, J2=2.9 Hz, 1H), 7.15-7.21 (m, 1H), 7.36-7.43 (m, 1H)

[0089] <Example 4-4> (Thermal phase change of compound C3-A6A-OC8 (azobenzene derivative 4) by DSC measurement) The thermal phase transition temperature of compound C3-A6A-OC8 was measured using a differential scanning calorimeter, and the phase change occurred at the following temperature. Cr 31 Iso, Iso -5 Cr

[0090] <Examples 4-5> (Photoirradiation experiment of compound C3-A6A-OC8 (azobenzene derivative 4)) The crystalline-isotropic phase transition of the crystalline compound C3-A6A-OC8 in a glass sandwich cell at 29°C was observed using a polarized light microscope. The results are shown in Figure 4. In Figure 4, (a) is a polarized light microscope image showing the crystalline phase at 29°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 29°C, and (c) is a polarized light microscope image showing the state after irradiation with green light followed by irradiation with blue light (450 nm) at 29°C. As is clear from Figure 4, irradiation with green light induced a limited phase transition from the crystalline phase to the isotropic phase, and a dark-field image was observed under orthogonal nicols (see (b)). That is, the birefringence of the crystal disappeared upon irradiation with green light, confirming that it melted from a crystal to a liquid. However, irradiation of the isotropic phase with blue light did not induce a phase transition from the isotropic phase to the crystalline phase (see (c)).

[0091] <Example 5-1> (Synthesis of compound C4-A6-OAc (intermediate 5-1)) m-toluidine (1.07 g, 10 mmol) was mixed with 16 mL of distilled water and 4 mL of concentrated hydrochloric acid. While stirring at 0°C, a solution prepared by dissolving sodium nitrite (0.83 g, 12 mmol) in 5 mL of distilled water was added. Then, 20 mL of an aqueous solution of 3,5-difluorophenol (1.3 g, 10 mmol) and 4.7 g of sodium hydroxide was added to the resulting solution, and the mixture was stirred for 15 minutes. The resulting solution was cooled, acidified with hydrochloric acid, and then extracted with ethyl acetate. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was diluted with 50 mL of anhydrous dichloromethane, and 12.1 g (12 mmol) of triethylamine (TEA) was added. While stirring at 0°C under nitrogen, a mixture of 0.94 g (12 mmol) of acetyl chloride (AcCl) dissolved in 10 mL of dichloromethane (DCM) was added dropwise. The resulting solution was allowed to stand for 1 hour and then extracted with water. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was purified by silica gel column chromatography to obtain intermediate 5-1 shown below (orange solid, 2.22 g, yield: 75.5%). [ka]

[0092] Intermediate 5-1 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.31 (s, 3H), 2.45 (s, 3H), 6.88 (d, J= 10 Hz, 2H), 7.31 (dd, J1= 7.3 Hz, J2=1.9 Hz, 1H), 7.40 (t, J= 7.6 Hz, 1H), 7.73 (s, 1H), 7.74 (s, 1H)

[0093] <Example 5-2> (Synthesis of compound C4-A6A-OAc (intermediate 5-2)) 5 mL of 1,1,2,2-tetrachloroethane (TCE), trichloroisocyanuric acid (TCCA, 1.16 g, 5 mmol), potassium peroxodisulfate (1.6 g, 6 mmol), and tetrakis(triphenylphosphine)palladium(0) (0.15 g, 0.12 mmol) were added to compound C4-A6-OAc (intermediate 5-1, 1.45 g, 5 mmol), and the mixture was stirred at 110°C for 2 hours. The mixture was then filtered, and the solvent was removed from the filtrate under reduced pressure. The resulting solid was purified by silica gel column chromatography to obtain intermediate 5-2 shown below (red solid, 1.16 g, yield: 64.6%). [ka]

[0094] Intermediate 5-2 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.33 (s, 3H), 2.41 (s, 3H), 6.88 (d, J= 10 Hz, 2H), 6.94 (dd, J1= 9.3 Hz, J2=2.7 Hz, 1H), 7.14 (d, J=8.24 Hz, 1H), 7.29 (d, J=8.24 Hz, 1H)

[0095] <Example 5-3> (Synthesis of compound C4-A6A-OC8 (azobenzene derivative 5)) 5 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 160 mg, 4 mmol) were added to compound C4-A6A-OAc (intermediate 5-2, 0.36 g, 1 mmol), and the mixture was stirred at room temperature. A mixture of 5 mL of THF and 72 mg of distilled water was added dropwise to the reaction mixture, and the mixture was stirred at room temperature for 1 hour. A catalytic amount (0.05 mmol) of crown ether 18-crown-6 and 1-bromooctane (0.38 g, 2 mmol) was added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain azobenzene derivative 5 (orange solid, 0.4 g, yield: 91.6%) as shown below. [ka]

[0096] Azobenzene derivative 5 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.88-0.91 (m, 3H), 1.22-1.46 (m, 10H), 2.41 (s, 3H), 1.78-1.85 (m, 2H), 4.01 (t, J= 6.5 Hz, 2H), 6.60 (dd, J1= 11.1 Hz, J2=2.84Hz, 2H), 7.12 (d, J= 8.2 Hz, 1H), 7.28 (d, J= 8.2 Hz, 1H) 13C NMR (100 MHz, CDCl3): 14.11, 20.01, 22.66, 25.88, 28.83, 29.20, 31.79, 69.28, 99.21, 99.23, 99.44, 99.47, 123.01, 124.75, 124.85, 124.95, 126.88, 128.15, 128.56, 129.58, 136.42, 149.24, 156.41, 156.49, 159.02, 159.09

[0097] <Example 5-4> (Thermal phase change of compound C4-A6A-OC8 (azobenzene derivative 5) by DSC measurement) A chloroform solution of compound C4-A6A-OC8 was irradiated with ultraviolet light (365 nm) for 15 minutes to induce trans-cis isomerization. The solvent was removed from the mixture under reduced pressure, and the isomer mixture was separated by silica gel column chromatography to obtain cis-type azobenzene derivative 5 and trans-type azobenzene derivative 5. The thermal phase transition temperature of compound C4-A6A-OC8 was measured using a differential scanning calorimeter, and the phase change occurred at the following temperature. Trans Cr 51 Iso, Iso 21 Cr For the cis-type azobenzene derivative 5, no crystallization peak was observed even when cooled to -50°C using DSC.

[0098] <Example 5-5> (Measuring isomerization reaction enthalpy and crystallization enthalpy of compound C4-A6A-OC8 (azobenzene derivative 5) by DSC measurement) The energy released during thermally induced cis-trans isomerization (ΔHisom) of compound C4-A6A-OC8 and subsequent recrystallization (ΔHcryst) of the trans compound C4-A6A-OC8 was measured using differential scanning calorimeter, yielding the following results. ΔH isom = -56.7 J / g (-24.3 kJ / mol), ΔH cryst = -57.5 J / g (-24.7 kJ / mol)

[0099] <Examples 5 and 6> (Photoirradiation experiment of compound C4-A6A-OC8 (azobenzene derivative 5)) The crystalline-isotropic phase transition of the crystalline compound C4-A6A-OC8 in a glass sandwich cell at 23°C was observed using a polarized light microscope. The results are shown in Figure 5. In Figure 5, (a) is a polarized light microscope image showing the crystalline phase at 23°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 23°C, and (c) is a polarized light microscope image showing the state after irradiation with blue light (450 nm) at 23°C following green light irradiation. As is clear from Figure 5, irradiation with green light caused a phase transition from the crystalline phase to the isotropic phase, and a change from bright-field to dark-field observation was observed under orthogonal nicols (see (b)). Irradiation with green light caused the birefringence of the crystal to disappear, confirming that it had melted from a crystal to a liquid. Furthermore, when the isotropic phase (liquid phase) was irradiated with blue light, the birefringence of the crystal reappeared. From this, it was confirmed that a phase transition from the isotropic phase to the crystalline phase occurred and a crystal was formed (see (c)).

[0100] <Example 5-7> (Sunlight irradiation experiment of compound C4-A6A-OC8 (azobenzene derivative 5)) The crystalline-isotropic phase transition of the crystalline compound C4-A6A-OC8 was observed in a glass sandwich cell irradiated with sunlight at 23°C. The results are shown in Figure 6. In Figure 6, (a) shows the state before exposure, (b) shows the state after exposure to sunlight for several hours, and (c) shows the temperature of the glass substrate surface recorded during exposure. In (c), the left figure represents the time of sunrise, the center figure represents the time of solar noon, and the right figure represents the time of sunset. As is clear from Figure 6, even in experiments conducted at temperatures considerably lower than the phase transition temperature from the crystalline phase to the isotropic phase, irradiation with sunlight induced a phase transition from the crystalline phase to the isotropic phase.

[0101] <Example 5-8> (Calculation of the liquid phase stability of compound C4-A6A-OC8 (azobenzene derivative 5)) The rate constant (k) for thermal isomerization was measured at 40°C, 50°C, 60°C, 70°C, 80°C, and 90°C, respectively. Using these values ​​and an Arrhenius plot, the lifetime at 30°C was calculated to be 43.0 days.

[0102] <Example 6-1> (Synthesis of compound C2-A5A-OC4 (azobenzene derivative 9)) 5 mL of tetrahydrofuran (THF), sodium ethoxide (34 mg, 0.5 mmol), and a catalytic amount (0.01 mmol) of crown ether 18-crown-6 were added to compound C2-A5A-OAc (intermediate 3-4, 75 mg, 0.2 mmol), and the mixture was stirred at room temperature for 2 hours. Then, 1-bromobutane (68 mg, 0.5 mmol) was added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain the azobenzene derivative 9 shown below (orange solid, 51 mg, yield: 65.3%). [ka]

[0103] Azobenzene derivative 9 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.99-1.02 (m, 3H), 1.42-1.84 (m, 4H), 2.36 (s, 6H), 3.73-3.86 (m, 2H), 7.08 (t, J= 8.6 Hz, 2H), 7.36-7.43 (m, 1H) 13C NMR (100 MHz, CDCl3): 14.07, 15.84, 19.70, 69.56, 73.72, 112.92, 112.95, 113.13, 113.16, 124.59, 124.61, 130.27, 130.32, 131.26, 131.36, 131.91, 132.00, 132.10, 146.15, 146.18, 154.56, 154.90, 156.46, 156.54, 157.45, 157.50

[0104] <Example 6-2> (Thermal phase change of compound C2-A5A-OC4 (azobenzene derivative 9) by DSC measurement) The thermal phase transition temperature of the trans isomer of compound C2-A5A-OC4 was measured using a differential scanning calorimeter, and the phase change occurred at the following temperature. Cr 76 ISO, ISO 54 Cr

[0105] (Photoirradiation experiment of compound C2-A5A-OC4 (azobenzene derivative 9)) The crystalline-isotropic phase transition of the crystalline compound C2-A5A-OC4 in a glass sandwich cell at 30°C was observed using a polarized light microscope. The results are shown in Figure 9. In Figure 9, (a) is a polarized light microscope image showing the crystalline phase at 30°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 30°C, and (c) is a polarized light microscope image showing the state after irradiation with green light followed by irradiation with blue light (450 nm) at 30°C. As is clear from Figure 9, irradiation with green light caused a phase transition from the crystalline phase to the isotropic phase, and a change from bright-field to dark-field observation was observed under orthogonal nicols (see (b)). Irradiation with green light caused the birefringence of the crystal to disappear, confirming that it had melted from a crystal to a liquid. Furthermore, when the isotropic phase (liquid phase) was irradiated with blue light, the birefringence of the crystal reappeared. From this, it was confirmed that a phase transition from the isotropic phase to the crystalline phase occurred and a crystal was formed (see (c)).

[0106] <Example 7-1> (Synthesis of compound C2-A5A-OC5 (azobenzene derivative 10)) 5 mL of tetrahydrofuran (THF), sodium ethoxide (34 mg, 0.5 mmol), and a catalytic amount (0.01 mmol) of crown ether 18-crown-6 were added to compound C2-A5A-OAc (intermediate 3-4, 75 mg, 0.2 mmol), and the mixture was stirred at room temperature for 2 hours. Then, 1-bromopentane (76 mg, 0.5 mmol) was added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain the azobenzene derivative 10 shown below (orange solid, 72 mg, yield: 88.6%). [ka]

[0107] Azobenzene derivative 10 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.94-0.98 (m, 3H), 1.38-1.52 (m, 4H), 1.80-1.87 (m, 2H) 2.36 (s, 6H), 3.74 (t, J= 6.6 Hz, 2H), 7.09 (t, J= 8.7 Hz, 2H), 7.38-7.42 (m, 1H) 13C NMR (100 MHz, CDCl3): 14.07, 14.37, 22.95, 28.60, 30.21, 74.01, 112.92, 112.95, 113.16, 124.60, 131.97, 146.15, 156.53

[0108] <Example 7-2> (Thermal phase change of compound C2-A5A-OC5 (azobenzene derivative 10) by DSC measurement) The thermal phase transition temperature of the trans isomer of compound C2-A5A-OC5 was measured using a differential scanning calorimeter, and the phase change occurred at the following temperature. Cr 76 ISO, ISO 35 Cr

[0109] <Example 7-3> (Photoirradiation experiment of compound C2-A5A-OC5 (azobenzene derivative 10)) The crystalline-isotropic phase transition of the crystalline compound C2-A5A-OC5 in a glass sandwich cell at 30°C was observed using a polarized light microscope. The results are shown in Figure 10. In Figure 10, (a) is a polarized light microscope image showing the crystalline phase at 30°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 30°C, and (c) is a polarized light microscope image showing the state after irradiation with green light followed by irradiation with blue light (450 nm) at 30°C. As is clear from Figure 10, irradiation with green light caused a phase transition from the crystalline phase to the isotropic phase, and a change from bright-field to dark-field observation was observed under orthogonal nicols (see (b)). Irradiation with green light caused the birefringence of the crystal to disappear, confirming that it had melted from a crystal to a liquid. Furthermore, when the isotropic phase (liquid phase) was irradiated with blue light, the birefringence of the crystal reappeared. From this, it was confirmed that a phase transition from the isotropic phase to the crystalline phase occurred and a crystal was formed (see (c)).

[0110] <Example 8-1> (Synthesis of compound C2-A5A-OC6 (azobenzene derivative 11)) 5 mL of tetrahydrofuran (THF), sodium ethoxide (34 mg, 0.5 mmol), and a catalytic amount (0.10 mmol) of crown ether 18-crown-6 were added to compound C2-A5A-OAc (intermediate 3-4, 75 mg, 0.2 mmol), and the mixture was stirred at room temperature for 2 hours. Then, 1-bromohexane (82 mg, 0.5 mmol) was added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain the azobenzene derivative 11 shown below (orange solid, 77 mg, yield: 92.3%). [ka]

[0111] Azobenzene derivative 11 1HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.91-0.94 (m, 3H), 1.33-1.52 (m, 6H), 1.79-1.86 (m, 2H) 2.36 (s, 6H), 3.74 (t, J= 6.6 Hz, 2H), 7.08 (t, J= 8.6 Hz, 2H), 7.36-7.42 (m, 1H) 13C NMR (100 MHz, CDCl3): 14.08, 14.40, 22.98, 26.12, 30.51, 32.08, 74.02, 112.92, 112.95, 113.11, 113.16, 124.61, 130.26, 131.89, 131.99, 132.09, 146.15, 154.86, 154.89, 156.55, 157.45, 157.49

[0112] (Thermal phase change of compound C2-A5A-OC6 (azobenzene derivative 11) by DSC measurement) The thermal phase transition temperature of the trans isomer of compound C2-A5A-OC6 was measured using a differential scanning calorimeter, and the phase change occurred at the following temperatures. Cr 59 ISO, ISO 34 Cr

[0113] (Photoirradiation experiment of compound C2-A5A-OC6 (azobenzene derivative 11)) The crystalline-isotropic phase transition of the crystalline compound C2-A5A-OC6 in a glass sandwich cell at 30°C was observed using a polarized light microscope. The results are shown in Figure 11. In Figure 11, (a) is a polarized light microscope image showing the crystalline phase at 30°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 30°C, and (c) is a polarized light microscope image showing the state after irradiation with green light followed by irradiation with blue light (450 nm) at 30°C. As is clear from Figure 11, irradiation with green light caused a phase transition from the crystalline phase to the isotropic phase, and a change from bright-field to dark-field observation was observed under orthogonal nicols (see (b)). Irradiation with green light caused the birefringence of the crystal to disappear, confirming that it had melted from a crystal to a liquid. Furthermore, when the isotropic phase (liquid phase) was irradiated with blue light, the birefringence of the crystal reappeared. From this, it was confirmed that a phase transition from the isotropic phase to the crystalline phase occurred and a crystal was formed (see (c)).

[0114] <Example 9-1> (Synthesis of compound C2-A5A-OC7 (azobenzene derivative 12)) 5 mL of tetrahydrofuran (THF), sodium ethoxide (34 mg, 0.5 mmol), and a catalytic amount (0.01 mmol) of crown ether 18-crown-6 were added to compound C2-A5A-OAc (intermediate 3-4, 75 mg, 0.2 mmol), and the mixture was stirred at room temperature for 2 hours. Then, 1-bromoheptane (90 mg, 0.5 mmol) was added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain the azobenzene derivative 12 shown below (orange solid, 59 mg, yield: 68.2%). [ka]

[0115] Azobenzene derivative 12 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.89-0.92 (m, 3H), 1.25-1.56 (m, 8H), 1.76-1.85 (m, 2H) 2.35 (s, 6H), 3.73 (t, J= 6.6 Hz, 2H), 7.08 (t, J= 8.6 Hz, 2H), 7.37-7.41 (m, 1H) 13C NMR (100 MHz, CDCl3): 12.68, 13.04, 21.59, 24.99, 28.15, 29.14, 30.74, 72.62, 111.52, 111.55, 111.71, 111.76, 123.20, 128.86, 130.58, 130.68, 132.09, 144.75, 153.46, 155.14, 156.06, 156.10

[0116] <Example 9-2> (Thermal phase change of compound C2-A5A-OC7 (azobenzene derivative 12) by DSC measurement) When the thermal transition temperature of the trans isomer of compound C2-A5A-OC7 was measured with a differential scanning calorimeter, a phase change occurred at the following temperatures. Cr 62 Iso, Iso 20 Cr

[0117] <Example 9-3> (Photoirradiation experiment of compound C2-A5A-OC7 (azobenzene derivative 12)) The crystal phase-isotropic phase transition of the crystalline compound C2-A5A-OC7 in a glass sandwich cell at 30 °C was observed with a polarized light optical microscope. The results are shown in Fig. 12. In Fig. 12, (a) is a polarized light optical microscope photograph showing the crystal phase at 30 °C, (b) is a polarized light optical microscope photograph showing the state irradiated with green light (540 nm) at 30 °C, and (c) is a polarized light optical microscope photograph showing the state irradiated with blue light (450 nm) at 30 °C after irradiation with green light, respectively. As is clear from Fig. 12, irradiation with green light caused a phase transition from the crystal phase to the isotropic phase, and a change from a bright field to a dark field was observed under cross Nicol observation (see (b)). It was confirmed that the birefringence of the crystal disappeared due to irradiation with green light, and the crystal melted into a liquid. Also, when blue light was irradiated to the isotropic phase (liquid phase), the birefringence of the crystal appeared. From this, it was confirmed that a phase transition from the isotropic phase to the crystal phase occurred and crystals were formed (see (c)).

[0118] <Example 10-1> (Synthesis of compound C4-A6A-OC1 (azobenzene derivative 13)) 5 mL of tetrahydrofuran (THF), sodium hydride (60% in paraffin, 2 mmol) was added to compound C4-A6A-OAc (intermediate 5-2, 0.36 g, 0.5 mmol), and then the mixture was stirred at room temperature. A mixture of 5 mL of THF and 36 mg of distilled water was added dropwise to the reaction mixture, and then the mixture was stirred at room temperature for 1 hour. Then, a catalytic amount (0.02 mmol) of crown ether 18-crown-6 and methyl p-toluenesulfonate (TsOMe, 0.38 g, 2 mmol) were added to the reaction mixture, and the mixture was stirred at 66 °C for 22 hours. The solvent was distilled off from the mixture under reduced pressure, and the obtained solid was purified by silica gel column chromatography to obtain the azobenzene derivative 13 shown below (orange solid, 0.15 g, yield: 90.5%). [Chemical Structure]

[0119] The azobenzene derivative 13 was 1 analyzed by 1H NMR and 13 13C NMR to determine the structure. 1H NMR (400 MHz, CDCl3): 2.39 (s, 3H), 3.85 (s, 3H), 6.60 (d-d, J1 = 11.1 Hz, J2 = 2.84 Hz, 2H), 7.10 (d-d, J1 = 8.24 Hz, J2 = 0.68 Hz, 1H), 7.27 (d, J = 8.3 Hz, 1H) 13C NMR (100 MHz, CDCl3): 20.31, 56.59, 99.21, 99.24, 99.45, 99.48, 123.36, 127.26, 128.55, 130.04, 136.85, 149.58, 156.74, 156.81, 159.35, 159.42, 163.29, 163.43, 163.57

[0120] <Example 10-2> (Thermal phase change of compound C4-A6A-OC1 (azobenzene derivative 13) by DSC measurement) The thermal phase transition temperature of the trans isomer of compound C4-A6A-OC1 was measured using a differential scanning calorimeter, and the phase change occurred at the following temperature. Cr 67 ISO, ISO 33 Cr

[0121] <Example 10-3> (Photoirradiation experiment of compound C4-A6A-OC1 (azobenzene derivative 13)) The crystalline-isotropic phase transition of the crystalline compound C4-A6A-OC1 in a glass sandwich cell at 30°C was observed using a polarized light microscope. The results are shown in Figure 13. In Figure 13, (a) is a polarized light microscope image showing the crystalline phase at 30°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 30°C, and (c) is a polarized light microscope image showing the state after irradiation with green light followed by irradiation with blue light (450 nm) at 30°C. As is clear from Figure 13, irradiation with green light caused a phase transition from the crystalline phase to the isotropic phase, and a change from bright-field to dark-field observation was observed under orthogonal nicols (see (b)). Irradiation with green light caused the birefringence of the crystal to disappear, confirming that it had melted from a crystal to a liquid. Furthermore, when the isotropic phase (liquid phase) was irradiated with blue light, the birefringence of the crystal reappeared. From this, it was confirmed that a phase transition from the isotropic phase to the crystalline phase occurred and a crystal was formed (see (c)).

[0122] <Example 11-1> (Synthesis of compound C4-A6A-OC2 (azobenzene derivative 14)) 5 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 160 mg, 4 mmol) were added to compound C4-A6A-OAc (intermediate 5-2, 0.72 g, 1 mmol), and the mixture was stirred at room temperature. A mixture of 5 mL of THF and 72 mg of distilled water was added dropwise to the reaction mixture, and the mixture was stirred at room temperature for 1 hour. Then, a catalytic amount (0.05 mmol) of crown ether 18-crown-6 and ethyl p-toluenesulfonate (TsOEt, 0.80 g, 4 mmol) were added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain the azobenzene derivative 14 shown below (orange solid, 0.24 g, yield: 70.1%). [ka]

[0123] Azobenzene derivative 14 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 1.42-1.46 (m, 3H), 2.39 (s, 3H), 4.05-4.11 (m, 2H), 6.60 (dd, J1= 11.1 Hz, J2=2.84 Hz, 2H), 7.11 (d, J= 8.24 Hz, 1H), 7.28 (d, J= 8.24Hz, 1H) 13C NMR (100 MHz, CDCl3): 14.78, 20.32, 65.21, 99.56, 99.60, 99.80, 99.84, 123.40, 125.31, 127.28, 128.53, 129.97, 136.81, 149.63, 156.77, 156.84, 159.38, 159.45, 162.69, 162.83, 162.97

[0124] <Example 11-2> (Thermal phase change of compound C4-A6A-OC2 (azobenzene derivative 14) by DSC measurement) The thermal phase transition temperature of the trans isomer of compound C4-A6A-OC2 was measured using differential scanning calorimeter, and the phase change occurred at the following temperature. Although the compound was cooled to -50°C at a cooling rate of 2°C / min, no signal originating from crystallization during cooling was observed. Cr 65 ISO

[0125] <Example 11-3> (Photoirradiation experiment of compound C4-A6A-OC2 (azobenzene derivative 14)) The crystalline-isotropic phase transition of the crystalline compound C4-A6A-OC2 in a glass sandwich cell at 30°C was observed using a polarized light microscope. The results are shown in Figure 14. In Figure 14, (a) is a polarized light microscope image showing the crystalline phase at 30°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 30°C, and (c) is a polarized light microscope image showing the state after irradiation with blue light (450 nm) at 30°C following green light irradiation. As is clear from Figure 14, irradiation with green light caused a phase transition from the crystalline phase to the isotropic phase, and a change from bright-field to dark-field observation was observed under orthogonal nicols (see (b)). Irradiation with green light caused the birefringence of the crystal to disappear, confirming that it had melted from a crystal to a liquid. Furthermore, when the isotropic phase (liquid phase) was irradiated with blue light, the birefringence of the crystal reappeared. From this, it was confirmed that a phase transition from the isotropic phase to the crystalline phase occurred and a crystal was formed (see (c)).

[0126] <Example 12-1> (Synthesis of compound C4-A6A-OC3 (azobenzene derivative 15)) 5 mL of tetrahydrofuran (THF), sodium hydride (60% in paraffin, 128 mg, 3.2 mmol) was added to compound C4-A6A-OAc (intermediate 5-2, 0.58 g, 0.8 mmol), and then the mixture was stirred at room temperature. A mixture of 5 mL of THF and 58 mg of distilled water was added dropwise to the reaction mixture, and then the mixture was stirred at room temperature for 1 hour. Then, a catalytic amount (0.04 mmol) of crown ether 18-crown-6 and 1-bromopropane (0.39 g, 3.2 mmol) were added to the reaction mixture, and the mixture was stirred at 66 °C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain the azobenzene derivative 15 shown below (orange solid, 0.23 g, yield: 79.7%). [Chemical formula]

[0127] The azobenzene derivative 15 was 1 analyzed by 1H NMR and 13 13C NMR to determine the structure. 1H NMR (400 MHz, CDCl3): 1.03 - 1.07 (m, 3H), 1.80 - 1.89 (m, 2H), 2.40 (s, 3H), 3.98 (t, J = 6.4 Hz, 2H) 6.60 (d-d, J1 = 11.2 Hz, J2 = 2.92 Hz, 2H), 7.11 (d, J = 8.24 Hz, 1H), 7.27 (d, J = 8.28 Hz, 1H) 13C NMR (100 MHz, CDCl3): 10.71, 20.34, 22.61, 71.10, 99.59, 99.62, 99.82, 99.86, 123.41, 125.29, 127.28, 128.53, 129.56, 149.65, 156.79, 156.86, 159.39, 159.46, 163.03, 163.18

[0128] <Example 12-2> (Thermal phase change of compound C4-A6A-OC3 (azobenzene derivative 15) by DSC measurement) The thermal phase transition temperature of the trans isomer of compound C4-A6A-OC3 was measured using differential scanning calorimeter, and the phase change occurred at the following temperature. Although the compound was cooled to -50°C at a cooling rate of 2°C / min, no signal originating from crystallization during cooling was observed. Cr 61 ISO

[0129] <Example 12-3> (Photoirradiation experiment of compound C4-A6A-OC3 (azobenzene derivative 15)) The crystalline-isotropic phase transition of the crystalline compound C4-A6A-OC3 in a glass sandwich cell at 30°C was observed using a polarized light microscope. The results are shown in Figure 15. In Figure 15, (a) is a polarized light microscope image showing the crystalline phase at 30°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 30°C, and (c) is a polarized light microscope image showing the state after irradiation with blue light (450 nm) at 30°C following green light irradiation. As is clear from Figure 15, irradiation with green light induced a phase transition from the crystalline phase to the isotropic phase, and a dark-field was observed in crossed nicol observation (see (b)). Furthermore, when the isotropic phase was irradiated with blue light, a phase transition from the isotropic phase to the crystalline phase was induced, and crystals were formed (see (c)).

[0130] <Example 13-1> (Synthesis of compound C4-A6A-OC4 (azobenzene derivative 16)) 5 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 128 mg, 3.2 mmol) were added to compound C4-A6A-OAc (intermediate 5-2, 0.58 g, 0.8 mmol), and the mixture was stirred at room temperature. A mixture of 5 mL of THF and 58 mg of distilled water was added dropwise to the reaction mixture, and the mixture was stirred at room temperature for 1 hour. Then, a catalytic amount (0.04 mmol) of crown ether 18-crown-6 and 1-bromobutane (0.44 g, 3.2 mmol) were added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain the azobenzene derivative 16 shown below (orange solid, 0.14 g, yield: 47.6%). [ka]

[0131] Azobenzene derivative 16 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.97-1.01 (m, 3H), 1.45-1.5 (m, 2H), 1.77-1.83 (m, 2H), 2.40 (s, 3H), 4.02 (t, J= 6.5 Hz, 2H), 6.60 (dd, J1= 11.1 Hz, J2=2.96 Hz, 2H), 7.11 (d, J= 8.24 Hz, 1H), 7.27 (d, J= 8.24 Hz, 1H) 13C NMR (100 MHz, CDCl3): 14.09, 19.47, 20.22, 20.34, 31.23, 69.35, 99.58, 99.61, 99.82, 99.85, 127.28, 128.53, 129.95, 130.02, 136.80, 149.65, 159.79, 156.86, 159.39, 159.46, 162.91, 163.05

[0132] <Example 13-2> (Thermal phase change of compound C4-A6A-OC4 (azobenzene derivative 16) by DSC measurement) The thermal phase transition temperature of the trans isomer of compound C4-A6A-OC4 was measured using differential scanning calorimeter, and the phase change occurred at the following temperature. Although the compound was cooled to -50°C at a cooling rate of 2°C / min, no signal originating from crystallization during cooling was observed. Cr 47 ISO

[0133] <Example 13-3> (Photoirradiation experiment of compound C4-A6A-OC4 (azobenzene derivative 16)) The crystalline-isotropic phase transition of the crystalline compound C4-A6A-OC4 in a glass sandwich cell at 30°C was observed using a polarized light microscope. The results are shown in Figure 16. In Figure 16, (a) is a polarized light microscope image showing the crystalline phase at 30°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 30°C, and (c) is a polarized light microscope image showing the state after irradiation with blue light (450 nm) at 30°C following green light irradiation. As is clear from Figure 16, irradiation with green light induced a phase transition from the crystalline phase to the isotropic phase, and a dark-field was observed in crossed nicol observation (see (b)). Furthermore, when the isotropic phase was irradiated with blue light, a phase transition from the isotropic phase to the crystalline phase was induced, and crystals were formed (see (c)).

[0134] <Example 14-1> (Synthesis of compound C4-A6A-OC5 (azobenzene derivative 17)) 5 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 80 mg, 2 mmol) were added to compound C4-A6A-OAc (intermediate 5-2, 0.36 g, 0.5 mmol), and the mixture was stirred at room temperature. A mixture of 5 mL of THF and 36 mg of distilled water was added dropwise to the reaction mixture, and the mixture was stirred at room temperature for 1 hour. Then, a catalytic amount (0.02 mmol) of crown ether 18-crown-6 and 1-bromopentane (0.27 g, 2 mmol) were added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain the azobenzene derivative 17 shown below (orange solid, 0.19 g, yield: 100.0%). [ka]

[0135] Azobenzene derivative 17 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.92-0.96 (m, 3H), 1.36-1.47 (m, 4H), 1.78-1.84 (m, 2H), 2.40 (s, 3H), 4.01 (t, J= 6.5 Hz, 2H), 6.59 (dd, J1= 11.2 Hz, J2=2.92 Hz, 2H), 7.11 (d, J= 8.24 Hz, 1H), 7.27 (d, J= 8.24 Hz, 1H) 13C NMR (100 MHz, CDCl3): 14.33, 20.32, 22.74, 28.39, 28.91, 69.65, 99.5781, 99.61, 99.81, 99.84, 123.41, 125.28, 127.28, 128.53, 129.95, 149.64, 156.79, 156.86, 159.06, 159.39, 159.46, 162.90, 163.04, 163.18

[0136] <Example 14-2> (Thermal phase change of compound C4-A6A-OC5 (azobenzene derivative 17) by DSC measurement) The thermal phase transition temperature of the trans isomer of compound C4-A6A-OC5 was measured using differential scanning calorimeter, and the phase change occurred at the following temperature. Although the compound was cooled to -50°C at a cooling rate of 2°C / min, no signal originating from crystallization during cooling was observed. Cr 50 ISO <Example 14-3> (Photoirradiation experiment of compound C4-A6A-OC5 (azobenzene derivative 17)) The crystalline-isotropic phase transition of the crystalline compound C4-A6A-OC5 in a glass sandwich cell at 30°C was observed using a polarized light microscope. The results are shown in Figure 17. In Figure 17, (a) is a polarized light microscope image showing the crystalline phase at 30°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 30°C, and (c) is a polarized light microscope image showing the state after irradiation with blue light (450 nm) at 30°C following green light irradiation. As is clear from Figure 17, irradiation with green light induced a phase transition from the crystalline phase to the isotropic phase, and a dark-field was observed in crossed nicol observation (see (b)). Furthermore, when the isotropic phase was irradiated with blue light, a phase transition from the isotropic phase to the crystalline phase was induced, and crystals were formed (see (c)).

[0137] <Example 15-1> (Synthesis of compound C5-B2-OAc (intermediate 18-1)) A mixture was obtained by adding 16 mL of distilled water and 4 mL of concentrated hydrochloric acid to o-toluidine (1.07 g, 10 mmol). A solution prepared by dissolving sodium nitrite (0.83 g, 12 mmol) in 5 mL of distilled water was added to the mixture while stirring at 0°C. The resulting solution was then added to 20 mL of an aqueous solution of thymol (1.5 g, 10 mmol) and sodium hydroxide (4.7 g), and the resulting mixture was stirred for 15 minutes. The resulting solution was acidified with hydrochloric acid under cooling and extracted with ethyl acetate. The organic layer was washed with saline solution and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was diluted with 50 mL of anhydrous dichloromethane (DCM), and 12.1 g (12 mmol) of triethylamine (TEA) was added. While stirring at 0°C under nitrogen, a mixture of 0.94 g (12 mmol) of acetyl chloride (AcCl) in 10 mL of dichloromethane was added dropwise. The resulting solution was left to stand for 1 hour and then extracted with water. The organic layer was washed with brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was purified by silica gel column chromatography to obtain intermediate 18-1 shown below (orange solid, 2.18 g, yield: 70.2%). [ka]

[0138] Intermediate 18-1 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 1.23 (s, 3H), 1.25 (s, 3H), 2.35 (s, 3H), 2.68 (s, 3H), 2.73, (s, 3H), 2.96-3.06, (m, 1H), 6.99 (s, 1H), 7.23-7.35 (m, 3H), 7.59 (d, J= 7.7 Hz, 1H), 7.62 (s, 1H)

[0139] <Example 15-2> (Synthesis of compound C5-B2A-OAc (intermediate 18-2)) 5 mL of 1,1,2,2-tetrachloroethane (PCE), trichloroisocyanuric acid (TCCA, 0.46 g, 2 mmol), potassium peroxodisulfate (0.6 g, 2.4 mmol), and tetrakis(triphenylphosphine)palladium(0) (Pd(PPh3) 4.55 mg, 48 μmol) were added to compound C5-B2-OAc (intermediate 18-1, 0.62 g, 2 mmol), and the mixture was stirred at 110°C for 2 hours. The mixture was then filtered, and the solvent was removed from the filtrate under reduced pressure. The resulting solid was purified by silica gel column chromatography to obtain intermediate 18-2 shown below (red solid, 0.43 g, yield: 62.4%). [ka]

[0140] Intermediate 18-2 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 1.24 (s, 3H), 1.26 (s, 3H), 2.31 (s, 3H), 2.37 (s, 3H), 2.65, (s, 3H), 2.99-3.06, (m, 1H), 7.02 (s, 1H), 7.14-7.19 (m, 2H), 7.35-7.37 (m, 1H), 7.67 (s, 1H)

[0141] <Example 15-3> (Synthesis of compound C5-B2A-OMe (azobenzene derivative 18)) 5 mL of tetrahydrofuran (THF), sodium ethoxide (68 mg, 1.0 mmol), and a catalytic amount (0.03 mmol) of crown ether 18-crown-6 were added to compound C5-B2A-OAc (intermediate 18-3, 190 mg, 0.5 mmol). The mixture was then stirred at room temperature for 2 hours. Next, methyl p-toluenesulfonate (TsOMe, 0.19 g, 1.0 mmol) was added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain the azobenzene derivative 18 shown below (orange solid, 55 mg, yield: 31.7%). [ka]

[0142] Azobenzene derivative 18 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 1.23 (s, 3H), 1.25 (s, 3H), 2.32 (s, 3H), 2.68 (s, 3H), 3.24-3.31 (m, 1H), 3.91 (s, 3H), 6.78 (s, 1H), 7.12 (t, J= 7.6 Hz, 1H), 7.15-7.17 (m, 1H), 7.32-7.35 (m, 1H), 7.69 (s, 1H) 13C NMR (100 MHz, CDCl3): 17.96, 19.35, 22.89, 27.33, 55.97, 112.46, 114.05, 128.04, 128.47, 130.19, 131.61, 135.99, 139.00, 160.52

[0143] <Example 15-4> (Thermal phase change of compound C5-B2A-OMe (azobenzene derivative 18) by DSC measurement) The thermal phase transition temperature of the trans isomer of compound C5-B2A-OMe was measured using differential scanning calorimeter, and the phase change occurred at the following temperature. Although the compound was cooled to -50°C at a cooling rate of 2°C / min, no signal originating from crystallization during cooling was observed. Cr 74 ISO

[0144] <Example 15-5> (Photoirradiation experiment of compound C5-B2A-OMe (azobenzene derivative 18)) The crystalline-isotropic phase transition of the crystalline compound C5-B2A-OMe in a glass sandwich cell at 23°C was observed using a polarized light microscope. The results are shown in Figure 18. In Figure 18, (a) is a polarized light microscope image showing the crystalline phase at 30°C, (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 30°C, and (c) is a polarized light microscope image showing the state after irradiation with blue light (450 nm) at 30°C following irradiation with green light. As is clear from Figure 18, irradiation with green light induced a phase transition from the crystalline phase to the isotropic phase, and a dark-field was observed in crossed nicol observation (see (b)). Furthermore, when the isotropic phase was irradiated with blue light, a phase transition from the isotropic phase to the crystalline phase was induced, and crystals were formed (see (c)).

[0145] <Reference example 1-1> (Synthesis of compound C3-A1-OAc (intermediate 6-1)) Aniline (1.86 g, 20 mmol) was mixed with 24 mL of distilled water and 6 mL of concentrated hydrochloric acid. While stirring at 0°C, a solution prepared by dissolving sodium nitrite (1.66 g, 24 mmol) in 10 mL of distilled water was added. The resulting solution was then added to 30 mL of aqueous solution of phenol (1.88 g, 20 mmol) and sodium hydroxide (7.05 g), and stirred for 15 minutes. The resulting solution was cooled, acidified with hydrochloric acid, and then extracted with ethyl acetate. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was diluted with 50 mL of anhydrous dichloromethane, and 24.2 g (24 mmol) of triethylamine (TEA) was added. While stirring at 0°C under nitrogen, a mixture of 1.88 g (24 mmol) of acetyl chloride (AcCl) dissolved in 10 mL of dichloromethane (DCM) was added dropwise. The resulting solution was left to stand for 1 hour and then extracted with water. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was purified by silica gel column chromatography to obtain intermediate 6-1 shown below (orange solid, 4.6 g, yield: 80.2%). [ka]

[0146] Intermediate 6-1 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.29 (s, 3H), 7.23 (dd, J1= 4.8 Hz, J2=2.1 Hz, 2H), 7.42-7.51 (m, 3H), 7.90 (dd, J1= 6.9 Hz, J2=2.1 Hz, 2H), 7.95 (dd, J1= 4.8 Hz, J2=2.1Hz, 2H)

[0147] <Reference example 1-2> (Synthesis of compound C3-A1A-OAc (intermediate 6-2)) 5 mL of 1,1,2,2-tetrachloroethane (TCE), trichloroisocyanuric acid (TCCA, 0.70 g, 3 mmol), potassium peroxodisulfate (0.48 g, 1.8 mmol), and tetrakis(triphenylphosphine)palladium (0) (0.48 g) were added to compound C3-A1-OAc (intermediate 6-1, 0.36 g, 1.5 mmol), and the mixture was stirred at 110°C for 2 hours. The mixture was then filtered, and the solvent was removed from the filtrate under reduced pressure. The resulting solid was purified by silica gel column chromatography to obtain intermediate 6-2 shown below (red solid, 0.52 g, yield: 91.8%). [ka] Intermediate 6-2 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.34 (s, 3H), 7.23-7.29 (m, 3H), 7.44 (s, 1H), 7.46 (s, 1H)

[0148] <Reference example 1-3> (Synthesis of compound C3-A1A-OC8 (azobenzene derivative 6)) 5 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 192 mg, 4.8 mmol) were added to compound C3-A1A-OAc (intermediate 6-2, 0.45 g, 1.2 mmol), and the mixture was stirred at room temperature. 5 mL of a mixture of THF and 86 mg of distilled water was added dropwise to the reaction mixture, and the mixture was stirred at room temperature for 1 hour. A catalytic amount (0.06 mmol) of crown ether 18-crown-6 and 1-bromooctane (0.46 g, 2.4 mmol) were added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain azobenzene derivative 6 shown below (orange solid, 0.53 g, yield: 98.6%). [ka]

[0149] Azobenzene derivative 6 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.88-0.91 (m, 3H), 1.29-1.45 (m, 10H), 1.76-1.83 (m, 2H), 4.00 (t, J= 6.5 Hz, 2H), 7.00 (s, 2H), 7.21 (t, J= 8.4 Hz, 1H), 7.42 (d, J= 8.0Hz, 1H) 13C NMR (100 MHz, CDCl3): 14.14, 22.69, 25.90, 28.93, 29.23, 29.28, 31.82, 69.05, 115.90, 126.92, 128.94, 129.23, 130.11, 140.31, 148.33, 159.76

[0150] <Reference example 1-4> Thermal phase change of compound C3-A1A-OC8 (azobenzene derivative 6) by DSC measurement. The thermal phase transition temperature of compound C3-A1A-OC8 was measured using a differential scanning calorimeter, and the phase change occurred at the following temperature. Cr 44 Iso, Iso 5 Cr

[0151] <Reference example 1-5> (Photoirradiation experiment of compound C3-A1A-OC8 (azobenzene derivative 6)) The crystalline-isotropic phase transition of the crystalline compound C3-A1A-OC8 in a glass sandwich cell at 29°C was observed using a polarized light microscope. The results are shown in Figure 7. In Figure 7, (a) is a polarized light microscope image showing the crystalline phase at 29°C, and (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 29°C. As is clear from Figure 7, irradiation with green light caused a phase transition from the crystalline phase to the isotropic phase, and a dark-field observation was observed under orthogonal nicols (see (b)). That is, irradiation with green light caused the birefringence of the crystal to disappear, confirming that it melted from a crystal to a liquid. However, irradiation of the isotropic phase with blue light did not induce a phase transition from the isotropic phase to the crystalline phase (see (c)).

[0152] <Reference example 1-6> (Calculation of the liquid phase stability of compound C3-A1A-OC8 (azobenzene derivative 6)) The rate constant (k) for thermal isomerization was measured at 50°C, 60°C, 70°C, 80°C, and 90°C, respectively. Using these values ​​and an Arrhenius plot, the lifetime at 30°C was calculated to be 5.8 days.

[0153] <Comparative Example 1-1> (Synthesis of compound C2-A6-OAc (intermediate 7-1)) 16 mL of distilled water and 4 mL of concentrated hydrochloric acid were added to 1.29 g of 2,6-difluoroaniline (10 mmol). While stirring at 0°C, a solution prepared by dissolving 0.83 g of sodium nitrite (12 mmol) in 5 mL of distilled water was added. Then, 20 mL of an aqueous solution of 1.3 g of 3,5-difluorophenol (10 mmol) and 4.7 g of sodium hydroxide was added to the resulting solution, and the mixture was stirred for 15 minutes. The resulting solution was cooled, acidified with hydrochloric acid, and then extracted with ethyl acetate. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was diluted with 50 mL of anhydrous dichloromethane, and 12.1 g (12 mmol) of triethylamine (TEA) was added. While stirring at 0°C under nitrogen, a mixture of 0.94 g (12 mmol) of acetyl chloride (AcCl) dissolved in 10 mL of dichloromethane (DCM) was added dropwise. The resulting solution was allowed to stand for 1 hour, then extracted with water. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was purified by silica gel column chromatography to obtain intermediate 7-1 shown below (orange solid, 2.9 g, yield: 92%). [ka]

[0154] Intermediate 7-1 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.32 (s, 3H), 6.92 (d, J= 9.4 Hz, 2H), 7.05 (t, J= 8.6 Hz,, 2H), 7.33-7.40 (m, 1H)

[0155] <Comparative Example 1-2> (Compound C2-A6A-OC8 (Azobenzene derivative 7)) 5 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 160 mg, 4 mmol) were added to compound C2-A6A-OAc (intermediate 7-1, 0.31 g, 1 mmol), and the mixture was stirred at room temperature. 5 mL of a mixture of THF and 72 mg of distilled water was added dropwise to the reaction mixture, and the mixture was stirred at room temperature for 1 hour. A catalytic amount (0.05 mmol) of crown ether 18-crown-6 and 1-bromooctane (0.38 g, 2 mmol) were added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain azobenzene derivative 7 (orange solid, 0.36 g, yield: 93.1%) as shown below. [ka]

[0156] Azobenzene derivative 7 1 HNMR and 13 The structure was determined by analysis using 13C NMR. 1H NMR (400 MHz, CDCl3): 0.88-0.91 (m, 3H), 1.30-1.45 (m, 10H), 1.77-1.83 (m, 2H), 3.99-4.03 (m, 2H), 6.36 (dd, J1=12Hz, J2=2.6 Hz, 1H), 6.58 (d, J1=11.2 Hz, 1H), 7.01-7.07 (m, 2H), 7.28-7.34 (m, 1H) 13C NMR (100 MHz, CDCl3): 14.29, 22.85, 26.06, 29.02, 29.39, 29.45, 69.41, 99.32, 99.36, 99.56, 99.59, 125.94, 126.04, 126.13, 130.39, 130.49, 130.59, 132.24, 132.34, 132.44, 154.37, 154.41, 156.36, 156.43, 158.96, 159.03

[0157] <Comparative Example 1-3> (Thermal phase change of compound C2-A6A-OC8 (azobenzene derivative 7) by DSC measurement) The thermal phase transition temperature of compound C2-A6A-OC8 was measured using a differential scanning calorimeter, and the phase change occurred at the following temperature. Cr 45 ISO, ISO 22 Cr

[0158] <Comparative Example 1-4> (Photoirradiation experiment of compound C2-A6A-OC8 (azobenzene derivative 7)) The crystalline-isotropic phase transition of the crystalline compound C2-A6A-OC8 in a glass sandwich cell at 29°C was observed using a polarized light microscope. The results are shown in Figure 8. In Figure 8, (a) is a polarized light microscope image showing the crystalline phase at 29°C, and (b) is a polarized light microscope image showing the state after irradiation with green light (540 nm) at 29°C. As is clear from Figure 8, the phase transition from the crystalline phase to the isotropic phase did not occur upon irradiation with green light. In other words, the azobenzene derivative did not undergo a phase transition from the solid phase to the liquid phase upon irradiation with green light.

[0159] <Comparative Example 1-5> (Calculation of the liquid phase stability of compound C2-A6A-OC8 (azobenzene derivative 7)) The rate constant (k) for thermal isomerization was measured at 60°C, 75°C, 85°C, and 90°C, respectively. Using these values ​​and an Arrhenius plot, the lifetime at 30°C was calculated to be 30.2 days.

[0160] <Comparative Example 2-1> (Synthesis of compound A1-B9-diOAc (intermediate 8-1)) 4-aminophenol (1.09 g, 10 mmol) was mixed with 16 mL of distilled water and 4 mL of concentrated hydrochloric acid. While stirring at 0°C, a solution prepared by dissolving sodium nitrite (0.83 g, 12 mmol) in 5 mL of distilled water was added. Then, 20 mL of an aqueous solution of o-cresol (1.08 g, 10 mmol) and 4.7 g of sodium hydroxide was added to the resulting solution, and the mixture was stirred for 15 minutes. The resulting solution was cooled, acidified with hydrochloric acid, and then extracted with ethyl acetate. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was diluted with 50 mL of anhydrous dichloromethane, and 24.2 g (24 mmol) of triethylamine (TEA) was added. While stirring at 0°C under nitrogen, a mixture of acetyl chloride (AcCl) (24 mmol) dissolved in 10 mL of dichloromethane (DCM) was added dropwise. The resulting solution was allowed to stand for 1 hour and then extracted with water. The organic layer was washed with saturated brine and dried on anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the resulting solid was purified by silica gel column chromatography to obtain intermediate 8-1 shown below (orange solid, 0.45 g, yield: 14.4%). [ka]

[0161] Intermediate 8-1 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.28 (s, 3H), 2.33 (s, 3H), 2.35 (s, 3H), 7.17 (d, J= 8.4 Hz, 1H), 7.24 (d, J= 8.8 Hz, 2H), 7.77-7.81 (m, 2H), 7.94 (d, J= 8.8 Hz, 2H)

[0162] <Comparative Example 2-2> (Synthesis of compound A1-B9A-diOAc (intermediate 8-2)) 5 mL of 1,1,2,2-tetrachloroethane (TCE), trichloroisocyanuric acid (TCCA, 0.94 g, 4 mmol), potassium peroxodisulfate (1.3 g, 4.8 mmol), and tetrakis(triphenylphosphine)palladium (0) (0.24 g, 0.2 mmol) were added to compound A1-B9-diOH (intermediate 8-1, 0.62 g, 2 mmol), and the mixture was stirred at 110°C for 2 hours. The mixture was then filtered, and the solvent was removed from the filtrate under reduced pressure. The resulting solid was purified by silica gel column chromatography to obtain intermediate 8-2 shown below (red solid, 0.42 g, yield: 48.6%). [ka]

[0163] Intermediate 8-2 1 The structure was determined by analysis using 1HNMR. 1H NMR (400 MHz, CDCl3): 2.28 (s, 3H), 2.33 (s, 3H), 2.37 (s, 3H), 7.21 (s, 1H), 7.28 (s, 2H)

[0164] <Comparative Example 2-3> (Synthesis of compound A1-B9A-diOC8 (azobenzene derivative 8)) 10 mL of tetrahydrofuran (THF) and sodium hydride (60% in paraffin, 160 mg, 4 mmol) were added to compound A1-B9A-diOAc (intermediate 8-2, 0.18 g, 0.5 mmol), and the mixture was stirred at room temperature. After stirring for 1 hour, a catalytic amount (0.025 mmol) of crown ether 18-crown-6 and 1-bromooctane (0.38 g, 2 mmol) were added to the reaction mixture, and the mixture was stirred at 66°C for 22 hours. The solvent was removed from the mixture under reduced pressure, and the resulting solid was purified by silica gel column chromatography to obtain azobenzene derivative 8 (orange solid, 0.25 g, yield: 84.4%) as shown below. [ka]

[0165] Azobenzene derivative 8 1 HNMR and 13 The structure was determined by analysis using 1CNMR. 1H NMR (400 MHz, CDCl3): 0.88-0.91 (m, 6H), 1.30-1.51 (m, 20H), 1.78-1.87 (m, 2H), 2.33 (s, 3H), 3.98 (m, 4H), 6.89 (s, 1H), 6.98 (s, 2H) 13C NMR (100 MHz, CDCl3): 12.85, 14.12, 22.67, 25.90, 26.04, 28.95, 29.04, 29.21, 29.23, 29.27, 31.81, 68.96, 69.09, 111.73, 115.74, 123.93, 125.84, 129.31, 130.17, 140.95, 141.26, 157.37, 159.11

[0166] <Comparative Example 2-4> (Thermal phase change of compound A1-B9A-diOC8 (azobenzene derivative 8) by DSC measurement) The thermal phase transition temperature of compound A1-B9A-diOC8 was measured using a differential scanning calorimeter, and the phase change occurred at the following temperature. Cr 91 ISO, ISO 85 Cr

[0167] <Comparative Example 2-5> (Photoirradiation experiment of compound A1-B9A-diOC8 (azobenzene derivative 8)) The crystalline-isotropic phase transition of the compound A1-B9A-diOC8 crystals was observed using a polarized light microscope in a glass sandwich cell at 29°C. The results are shown in Figure 9. In Figure 9, (a) is a polarized light microscope image showing the crystalline phase at 29°C, and (b) is a polarized light microscope image showing the sample irradiated with green light (540 nm) at 29°C. As is clear from Figure 9, the phase transition from the crystalline phase to the isotropic phase did not occur upon irradiation with green light. In other words, the azobenzene derivative did not undergo a phase transition from the solid phase to the liquid phase upon irradiation with green light.

[0168] <Comparative Example 2-6> (Calculation of the liquid phase stability of compound A1-B9A-diOC8 (azobenzene derivative 8)) The rate constant (k) for thermal isomerization was measured at 40°C, 45°C, 50°C, and 55°C, respectively. Using these values ​​and an Arrhenius plot, the lifetime at 30°C was calculated to be 4.8 days.

[0169] <Comparative Example 3-1> (Chlorination reaction of compound C2-A1-OH) 5 mL of 1,1,2,2-tetrachloroethane (TCE), trichloroisocyanuric acid (TCCA, 0.23 g, 1 mmol), potassium peroxodisulfate (0.33 g, 1.2 mmol), and tetrakis(triphenylphosphine)palladium(0) (0.03 g, 0.025 mmol) were added to compound C2-A1-OH (0.23 g, 1 mmol) and stirred at 110°C for 2 hours. However, the target compound was not obtained (the starting materials decomposed). [ka]

[0170] <Comparative Example 3-2> (Chlorination reaction of compound C2-A1-OTIPS) 5 mL of 1,1,2,2-tetrachloroethane (TCE), trichloroisocyanuric acid (TCCA, 0.23 g, 1 mmol), potassium peroxodisulfate (0.33 g, 1.2 mmol), and tetrakis(triphenylphosphine)palladium (0) (0.03 g, 0.025 mmol) were added to compound C2-A1-OTIPS (0.39 g, 1 mmol), and the mixture was stirred at 110°C for 2 hours. However, the target compound was not obtained (multiple decomposition products were obtained). [ka]

[0171] <Comparative Example 3-3> (Chlorination reaction of compound C2-A1-OC8) 5 mL of 1,1,2,2-tetrachloroethane (TCE), trichloroisocyanuric acid (TCCA, 0.23 g, 1 mmol), potassium peroxodisulfate (0.33 g, 1.2 mmol), and tetrakis(triphenylphosphine)palladium (0) (0.03 g, 0.025 mmol) were added to compound C2-A1-OC8 (0.35 g, 1 mmol), and the mixture was stirred at 110°C for 2 hours. However, the target compound was not obtained (multiple decomposition products were obtained). [ka]

Claims

1. an azobenzene derivative represented by the following formula (1), An azobenzene derivative capable of undergoing a phase transition from solid to liquid phase upon irradiation with visible light. (In formula (1), R １ represents an alkoxy group having 1 to 18 carbon atoms, and R ２ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ３ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R ３ represents a functional group different from R １ , X １ to X ４ each independently represents a halogen atom, and X １ to X ４ represent a combination of two or more kinds of halogen atoms.)

2. In the above formula (1), R ２ The azobenzene derivative according to claim 1, wherein one or more of them are branched C3-C4 alkyl groups.

3. In the above formula (1), R １ This represents an alkoxy group with 6 to 18 carbon atoms, X １ ~X ４ However, each independently represents a halogen atom, X １ ~X ４ The azobenzene derivative according to claim 1, wherein represents a combination of two or more halogen atoms.

4. In the above formula (1), X １ ~X ４ The azobenzene derivative according to claim 1, wherein the azobenzene derivative is a combination of two or more halogen atoms selected from the group consisting of fluorine atoms, chlorine atoms, and bromine atoms.

5. In the above formula (1), X １ and X ２ However, they are the same halogen atom, X ３ and X ４ However, X １ and X ２ The azobenzene derivative according to claim 1, wherein it is the same halogen atom but different from the one described above.

6. In the above formula (1), X １ ~X ４ The azobenzene derivative according to claim 1, wherein the azobenzene derivative is a combination of a fluorine atom and a chlorine atom.

7. In the above formula (1), R ２ The azobenzene derivative according to claim 1, wherein each is independently a hydrogen atom or a methyl group.

8. The azobenzene derivative according to claim 1, which is capable of undergoing a phase transition between a solid phase and a liquid phase by irradiation with visible light.

9. The azobenzene derivative according to claim 1, which undergoes a phase transition from a solid phase to a liquid phase when irradiated with visible light with a wavelength of 500 to 650 nm.

10. The azobenzene derivative according to claim 1, which undergoes a phase transition from a liquid phase to a solid phase when irradiated with visible light with a wavelength of 400 to 500 nm.

11. A method for producing an azobenzene derivative represented by the following formula (1), Step (A) involves contacting at least one azobenzene derivative selected from the group consisting of an azobenzene derivative represented by the following formula (2-1), an azobenzene derivative represented by the following formula (2-2), and an azobenzene derivative represented by the following formula (2-3) with a halogenating agent in the presence of a palladium compound to obtain an azobenzene derivative represented by the following formula (3), A method for producing an azobenzene derivative, comprising the steps of: (A) deprotecting the acetoxy group of the azobenzene derivative represented by the following formula (3) obtained in step (A) to obtain the azobenzene derivative represented by the above formula (1); and (B) in this order. (In formula (1), R １ R represents an alkoxy group having 1 to 18 carbon atoms. ２ Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ３ R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. ３ R １ It represents a different functional group, X １ ~X ４ Each of these independently represents a halogen atom or an alkyl group having 1 to 2 carbon atoms, X １ ~X ４ (One or more of these represent halogen atoms.) (In equations (2-1), (2-2), and (2-3), R' １ represents an acetoxy group, R ２ Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ３ X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. １ ~X ４ Each of these independently represents a halogen atom or an alkyl group having 1 to 2 carbon atoms. (In formula (3), R' １ represents an acetoxy group, R ２ Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ３ X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. １ ~X ４ Each of these independently represents a halogen atom or an alkyl group having 1 to 2 carbon atoms, X １ ~X ４ (One or more of these represent halogen atoms.)

12. In equations (2-1), (2-2), and (2-3) above, X １ ~X ４ However, each independently represents a halogen atom. In the above formula (3), X １ ~X ４ However, each independently represents a halogen atom, X １ ~X ４ A method for producing an azobenzene derivative according to claim 11, wherein represents a combination of two or more halogen atoms.

13. A photothermal energy storage material containing an azobenzene derivative according to any one of claims 1 to 10.

14. An adhesive containing the azobenzene derivative according to any one of claims 1 to 10.

15. An optical element containing the azobenzene derivative according to any one of claims 1 to 10.

16. An actuator material containing the azobenzene derivative according to any one of claims 1 to 10.

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