JP2015143196A - Azobenzene compound and heat pump system using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an azobenzene compound capable of changing a structure repeatedly without heating and a heat pump system using it.SOLUTION: An azobenzene compound expressed by the formula (1) and reacts by cis-trans isomerization by light radiation, is used as a heat medium of a heat pump system. The azobenzene compound expressed by the formula (1) is subjected to endotherm by melting latent heat when phase change from a solid phase trans body to a liquid phase cis body occurs, and is subjected to heat evolution when phase change from the liquid phase cis body to the solid phase trans body occurs.

Description

  The present invention relates to an azobenzene compound whose structure is changed by light irradiation and a heat pump system using the same.

  Conventionally, it is known that an azobenzene compound is isomerized from a cis form to a trans form or from a trans form to a cis form by irradiating light of a predetermined wavelength. In such an azobenzene compound, a cyclic azobenzene derivative that changes from a solid state trans form to a liquid state cis form upon irradiation with ultraviolet light has been reported (see Patent Document 1 and Non-Patent Document 1).

JP2011-256155A

Chemical Communications, 2011, 47, 1770-1772

  Since the above-mentioned cyclic azobenzene derivative undergoes a phase change from a solid to a liquid upon irradiation with ultraviolet light, it can be considered to be used as a heat medium for a heat pump system utilizing latent heat accompanying the phase change. However, in order to change the cyclic azobenzene derivative that has become a liquid cis form into a solid trans form, heating is required. That is, it is necessary to apply heat from the outside in order to release the heat pumped up by ultraviolet light irradiation. As a result, the amount of heat that can be effectively transferred from the low temperature side to the high temperature side is reduced, which is undesirable as a heat medium for the heat pump system.

  An object of this invention is to provide the azobenzene compound which can change a structure repeatedly without heating in view of the said point, and a heat pump system using the same.

  In order to achieve the above object, the azobenzene compound according to claim 1 of the present invention is represented by the general formula (1), and is characterized in that it undergoes a cis-trans isomerization reaction by light irradiation.

In general formula (1),
Y: N or CH.

R _{1 to} R ₃ : a linear or branched alkyl group having 1 to 12 carbon atoms.

_{R 4: (OCH 2 CH 2} ) n ( where n is an integer of 1 to _{3), (OCH 2 CH 2 CH} 2) n ( where n is an integer of 1 to _{3), R 10, O-R} 10, NHR ₁₀ , N (R ₁₀ ) (R ₁₁ ), COOR ₁₀ or CONHR ₁₀ .

R ₁₀ and R ₁₁ are linear or branched alkyl groups having 1 to 12 carbon atoms.

R ₉ : CH ₃ (OCH ₂ CH ₂ ) _n O (where n is an integer of 1 to 3), CH ₃ (OCH ₂ CH ₂ CH ₂ ) _n O (where n is an integer of 1 to 3), R ₁₀ , R ₁₀ O, R ₁₀ NH, (R ₁₀ ) (R ₁₁ ) N, R ₁₀ COO or R ₁₀ CONH.

R _{5 to} R ₈ are any one of H, F, R ₁₄ , OR _{14, and} N (R ₁₄ ) ₂ .

R ₁₄ is any one of H, CH ₃ , C ₂ H ₅ , C ₃ H ₇ or i-C ₃ H ₇ .

X ⁻ : Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CH ₃ (CH ₂ ) _n SO ₃ ⁻ (where n is an integer of 0 to 2), TsO ⁻ , (YSO ₂ ) ₂ N ^- (where _{Y = F, CF 3, C} 2 F 5), (NC) 2 N - is either.

  The azobenzene compound represented by the general formula (1) isomerizes from a trans isomer to a cis isomer by irradiating ultraviolet light as a first light irradiation trigger, and irradiates visible light as a second light irradiation trigger. It has the property of isomerizing from the cis form to the trans form. For this reason, the phase change from the solid phase to the liquid phase or from the liquid phase to the solid phase of the azobenzene compound is carried out by isomerizing the trans isomer and the cis isomer in the temperature range between the melting point of the cis isomer and the trans isomer. Can be triggered.

  The azobenzene compound represented by the general formula (1) undergoes endotherm due to latent heat of fusion when the phase transition from the solid phase trans form to the liquid phase cis form, and the liquid phase cis form changes to the solid phase trans form. When the phase changes, heat is generated due to the phase change. For this reason, by irradiating the solid phase trans form with ultraviolet light in a low temperature environment, the liquid phase cis form can change its phase and absorb heat. By irradiating, it is possible to generate heat by changing the phase to a solid-state trans form.

  And, using the azobenzene compound of the above general formula (1) as a heat medium of the heat pump system, by utilizing the latent heat accompanying the phase change of the azobenzene compound due to light irradiation, energy is externally used using a device such as a compressor. It is possible to transfer heat from a low temperature environment to a high temperature environment without charging. Thereby, it is possible to provide a heat pump system capable of transferring heat with less energy.

  Further, since the azobenzene compound has a high response speed to light stimulation, heat absorption and heat generation accompanying phase change are performed in a short time, and it can be suitably used as a heat medium for a heat pump system.

1 is a conceptual diagram of a heat pump system according to an embodiment of the present invention. It is a figure which shows the isomer of an azobenzene compound. It is a figure which shows the Gibbs free energy of an azobenzene compound. It is a graph which shows the absorption spectrum change at the time of irradiating the ultraviolet light to the trans body of an azobenzene compound. It is a graph which shows the absorption spectrum change at the time of irradiating visible light to the cis body of an azobenzene compound. It is a figure which shows the polarization microscope image before ultraviolet light irradiation of an azobenzene compound. It is a figure which shows the polarization microscope image after ultraviolet irradiation of an azobenzene compound. It is a figure which shows the polarization microscope image after visible light irradiation of an azobenzene compound.

  Hereinafter, an embodiment in which the azobenzene compound of the present invention is used as a heat medium of a heat pump system will be described with reference to FIGS.

  As shown in FIG. 1, the heat pump system includes a circulation path 10, a low temperature side heat exchanger 11, a high temperature side heat exchanger 12, and a circulation pump 13. The heat pump system is used in an environment where a temperature gradient exists such as a low temperature environment and a high temperature environment.

  In FIG. 1, the left side is the low temperature side and the right side is the high temperature side. The circulation path 10 is disposed across the low temperature side and the high temperature side. The low temperature side heat exchanger 11 is disposed on the low temperature side in the circulation path 10, and the high temperature side heat exchanger 12 is disposed on the high temperature side in the circulation path 10.

  The heat pump system of this embodiment is configured as an indoor heating device used in winter. That is, in the winter season when the outside air temperature is low, the low temperature side heat exchanger 11 is disposed outdoors (for example, 0 ° C.), and the high temperature heat exchanger 12 is disposed indoors (for example, 25 ° C.) to be used for indoor heating. Can do.

  A heat medium is enclosed in the circulation path 10, and the heat medium can circulate between the low temperature side heat exchanger 11 and the high temperature side heat exchanger 12. In this embodiment, an azobenzene compound is used as the heat medium. As the azobenzene compound, for example, a compound dissolved in an organic solvent such as chloroform can be encapsulated in a microcapsule.

  In the circulation path 10, a transportation fluid for transporting the microcapsules in which the azobenzene compound is sealed is also sealed. As the transport fluid, an antifreeze such as ethylene glycol can be used. The heat medium is sent together with the transport fluid by the circulation pump 13 and circulates in the circulation path 10.

  The low-temperature side heat exchanger 11 is provided with an ultraviolet light transmission part that can transmit at least ultraviolet light, and can irradiate the azobenzene compound passing through the interior with ultraviolet light from the outside. Moreover, the high temperature side heat exchanger 12 is provided with a visible light transmission part capable of transmitting at least visible light, and is capable of irradiating visible light from the outside to the azobenzene compound passing through the inside.

  The azobenzene compound used in the present embodiment is represented by the following general formula (1).

In the general formula (1), Y is N or CH.

R < ₁ > -R < ₃ > is a C1-C12 linear or branched alkyl group. R ₄ is (OCH ₂ CH ₂ ) _n (where n is an integer of 1 to 3), (OCH ₂ CH ₂ CH ₂ ) _n (where n is an integer of 1 to 3), R ₁₀ , O—R ₁₀ , NHR ₁₀ , N (R ₁₀ ) (R ₁₁ ), COOR ₁₀ or CONHR ₁₀ . R ₁₀ and R ₁₁ are each a linear or branched alkyl group having 1 to 12 carbon atoms.

R ₉ is CH ₃ (OCH ₂ CH ₂ ) _n O (where n is an integer of 1 to 3), CH ₃ (OCH ₂ CH ₂ CH ₂ ) _n O (where n is an integer of 1 to 3), R ₁₀ , R ₁₀ O, R ₁₀ NH, (R ₁₀ ) (R ₁₁ ) N, R ₁₀ COO, or R ₁₀ CONH.

R _{5 to} R ₈ are any one of H, F, R ₁₄ , OR _{14, and} N (R ₁₄ ) ₂ . R ₁₄ is H, CH ₃ , C ₂ H ₅ , C ₃ H _7, or i-C ₃ H ₇ .

X ⁻ represents Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CH ₃ (CH ₂ ) _n SO ₃ ⁻ (where n is an integer of 0 to 2), TsO ⁻ , (YSO ₂ ) _2. N ⁻ (where Y = F, CF ₃ , C ₂ F ₅ ), (NC) ₂ N ⁻ , preferably Cl ⁻ or Br ⁻ .

  As shown in FIG. 2, it is known that an azobenzene compound has trans and cis isomers. The trans isomer is more stable by about 50 kJ / mol than the cis isomer. The azobenzene compound of the present embodiment is isomerized from a trans form to a cis form by irradiating ultraviolet light (for example, wavelength 365 nm) as a first light irradiation trigger, and visible light (for example, wavelength 500 nm) as a second light irradiation trigger. Is isomerized from the cis form to the trans form. In addition, the azobenzene compound has a characteristic that the response speed to light stimulation is fast.

Next, the phase change of the azobenzene compound of this embodiment is demonstrated based on FIG. The vertical axis in FIG. 3 represents Gibbs free energy, and the horizontal axis represents temperature. As shown in FIG. 3, in the azobenzene compound of the present embodiment, the melting point Tm _{cis of the} cis isomer is lower than the melting point Tm _{trans of the} trans isomer. That is, in a temperature range higher than the melting point Tm _{cis of the} cis isomer and lower than the melting point Tm _{trans of the trans} isomer, the cis azobenzene compound is in a liquid phase and the trans azobenzene compound is in a solid phase. For this reason, the azobenzene compound of the present embodiment is obtained from the solid phase of the azobenzene compound by isomerizing the trans isomer and the cis isomer in a temperature range between the melting point Tm _{cis of the} cis isomer and the melting point Tm _trans of the _trans isomer. A phase change from a liquid phase or a liquid phase to a solid phase can be induced.

  The azobenzene compound of this embodiment can be transformed into a liquid cis isomer by irradiating the solid phase trans isomer with ultraviolet light, and can be solidified by irradiating the liquid cis isomer with visible light. The phase can be changed to a trans form of crystal (crystal). An azobenzene compound that isomerizes into a trans form of a solid phase (crystal) by irradiating visible light to a cis isomer in a liquid phase has not been reported so far, and is a characteristic property of the azobenzene compound of the present embodiment. .

  An azobenzene compound undergoes endotherm due to latent heat of fusion when it changes from a solid phase trans form to a liquid cis form, and changes phase when the liquid phase cis form changes to a solid phase trans form. The accompanying fever occurs. For this reason, by irradiating the solid phase trans form with ultraviolet light in a low temperature environment, the liquid phase cis form can change its phase and absorb heat. By irradiating, it is possible to generate heat by changing the phase to a solid-state trans form.

For this reason, the heat pump system according to the present embodiment is used under a temperature range between the melting point Tm _{cis of the} cis isomer and the melting point Tm _trans of the _trans isomer, so that the heat absorption and heat generation accompanying the phase change of the azobenzene compound are achieved. Can be used. That is, in the heat pump system, the temperature on the low temperature side where the low temperature side heat exchanger 11 is arranged is higher than the melting point Tm _{cis of the} cis body, and the temperature on the high temperature side where the high temperature side heat exchanger 12 is arranged is the melting point Tm of the transformer body. Use under _trans conditions.

  Under such conditions, the heat pump system operates as follows. First, the azobenzene compound is changed from a trans isomer to a cis isomer by irradiating the internal azobenzene compound with ultraviolet light through an ultraviolet light transmitting portion (not shown) of the low temperature side heat exchanger 11. The azobenzene compound absorbs heat in a low temperature environment due to the latent heat of fusion accompanying the phase change from the trans form (solid) to the cis form (liquid).

  The cis azobenzene compound is moved from the low temperature side heat exchanger 11 to the high temperature side heat exchanger 12 by the circulation pump 13. And an azobenzene compound changes from a cis body to a trans body by irradiating an internal azobenzene compound with visible light through the visible light transmission part (not shown) of the high temperature side heat exchanger 12. With the phase change from the cis form (liquid) to the trans form (solid), the azobenzene compound dissipates heat in a high temperature environment. In this way, heat can be transferred from the low temperature environment to the high temperature environment by using the latent heat accompanying the phase change of the azobenzene compound by light irradiation.

  In the present embodiment described above, the azobenzene represented by the above general formula (1) having a characteristic of absorbing heat by irradiating ultraviolet light in a low temperature environment and generating heat by irradiating visible light in a high temperature environment. By using the compound as a heat medium for the heat pump system, it is possible to perform heat absorption and heat generation without using external energy using a device such as a compressor. Thereby, heat can be transferred with less energy.

  Further, since the azobenzene compound has a high response speed to light stimulation, heat absorption and heat generation accompanying phase change are performed in a short time, and it can be suitably used as a heat medium for a heat pump system.

  Moreover, since the azobenzene compound of this embodiment is an ionic liquid, it is hard to volatilize and is stable at high temperature. Further, it can be expected that latent heat is increased as compared with other nonionic compounds having a similar structure due to the effect of Madelung energy.

  Here, “melting point” refers to the endothermic peak of the endothermic peak observed when the sample changes from the solid state to the liquid state in differential scanning calorimetry (DSC). The temperature at the intersection of tangent lines drawn at the inflection point.

  Further, “a temperature higher than the melting point” and “lower than the melting point” mean that the temperatures exist on the high temperature side not including the melting point and on the low temperature side not including the melting point, respectively.

Next, examples of the present invention will be described. In this example, R _{1 to} R ₃ in the general formula (1) are each C ₇ H ₁₅ , R ₄ is C ₄ H ₈ , R _{5 to} R ₈ are H, and R ₉ is C ₆ H. and _13, X ^- a Br ^- and the N represented by the following general formula (2), N, N-triheptyl - [4- (4'-hexyloxy-phenyl diazenyl) phenoxy butyl] ammonium bromide (hereinafter, "C ₆ AzoC ₄ N (C ₇ H ₁₅ ) ₃ ⁺ Br ⁻ ”) will be described.

Here, a method for producing the azobenzene compound C ₆ AzoC ₄ N (C ₇ H ₁₅ ) ₃ ⁺ Br ⁻ represented by the general formula (2) will be described.

As shown in the above synthetic scheme, C ₆ AzoC ₄ N (C ₇ H ₁₅ ) ₃ ⁺ Br ⁻ is 4- (hexyloxy) aniline, 4-((4-hexyloxyphenyl) diazenyl) phenol (C ₆ AzoC). ₄ OH) and C ₆ AzoC ₄ Br are synthesized through intermediate products.

  First, the synthesis of 4- (hexyloxy) aniline will be described.

In a 500 ml eggplant flask, 71.87 grams (520 mmol) of potassium carbonate (MW 138.20), 30.23 grams (200 mmol) of 4-acetamidophenol (MW 151.16), 1-bromohexane (M .W.165.07) 42.92 grams (260 mmol) was added. Thereto, 300 ml of acetone was added and refluxed for 18 hours. The reaction suspension was returned to room temperature and then added dropwise to 600 ml of water. The colorless precipitate that precipitated was filtered off and dried in vacuo. Thereafter, the suspension was suspended in 900 ml of hexane, stirred for 60 minutes, excess 1-bromohexane dissolved in hexane was removed, and recovered by filtration under reduced pressure.

  The obtained solid was put into a 500 ml eggplant flask, and 300 ml of a mixed solvent of methanol: 12N hydrochloric acid = 6: 4 (v / v) was added and refluxed. After 18 hours, the reaction solution was added dropwise to 600 ml of water, and the pH was adjusted to 6 to 7 using an aqueous NaOH solution. The appearing brown oil was extracted with ethyl acetate (100 ml × 6 times). After drying the organic phase with sodium sulfate, ethyl acetate was distilled off under reduced pressure to obtain 35.28 g (182.5 mmol) of a brown solid.

  All protons were assigned from the 1H-NMR spectrum measurement result of the obtained brown solid, and the disappearance of the C═O stretching vibration of the precursor was confirmed from the FT-IR spectrum measurement result of the light brown solid. This confirmed the synthesis of 4- (hexyloxy) aniline.

Next, the synthesis (diazo coupling) of 4-((4-hexoxyphenyl) diazenyl) phenol (C ₆ AzoC ₄ OH) will be described.

To a 1000 ml beaker, 8.23 grams (42.5 mmol) of 4-hexyloxyaniline (MW 193.29), 100 ml of water and 200 ml of acetone were added. Thereto was added 11.0 ml (132 mmol) of 12N hydrochloric acid, and this solution was cooled to 5 ° C. or lower in a chamber (the system was uneven). To this, a solution (5 ° C. or lower) of 3.81 g (55.2 mmol) of sodium nitrite (MW 69.01) dissolved in 15 ml of water was added dropwise with stirring in an ice bath (the system was Uniform). In addition, a solution of 5.27 grams (132 mmol) of sodium hydroxide (MW 39.9) and 5.20 grams (55.3 mmol) of phenol (MW 94.11) in 50 ml of water (5 C. or lower) was added to the previous solution (pH 8 to 9 after the dropwise addition), and the mixture was stirred for 4 hours in an ice bath. After stirring overnight at room temperature, 6N hydrochloric acid was added to adjust the pH to 4-5. Acetone was distilled off under reduced pressure, and the resulting precipitate was filtered off and recrystallized with 390 ml of ethanol: water = 2: 1 (v / v) mixed solvent. The obtained crystals were filtered off and dried under reduced pressure to obtain 9.93 g (33.3 mmol) of dark red crystals.

  All protons were assigned from the 1H-NMR spectrum measurement result of the obtained dark red crystal, and the formation of OH bond and -N = N- bond was suggested from the FT-IR spectrum measurement result of the dark red crystal. This confirmed the synthesis of 4-((4-hexoxyphenyl) diazenyl) phenol.

Next, the synthesis of C ₆ AzoC ₄ Br will be described.

In a 500 ml eggplant flask, 13.81 grams (99.9 mmol) of potassium carbonate (MW 138.21) and 9.93 grams (33.3 mmol) of C ₆ AzoOH (MW 298.38), 1,6 34.59 grams (160.2 mmol) of dibromobutane (MW 215.91) were added. 300 ml of acetone was added thereto and refluxed for 12 hours. After returning the reaction suspension to room temperature, the solvent was distilled off under reduced pressure, and 300 ml of water was added. The components insoluble in water were collected by filtration and recrystallized with 150 ml of ethyl acetate: chloroform = 2: 1 (v / v). The precipitated crystals were collected by filtration under reduced pressure to obtain 8.04 g (18.6 mmol) of pale yellow crystals.

All protons were assigned from the 1H-NMR spectrum measurement result of the obtained pale yellow crystal, and the disappearance of the OH bond was confirmed from the FT-IR spectrum measurement result of the pale yellow crystal. This confirmed the synthesis of C ₆ AzoC ₄ Br.

Next, synthesis of C ₆ AzoC ₄ N (C ₇ H ₁₅ ) ₃ ⁺ Br ⁻ will be described.

In a 50 ml eggplant flask, 1.50 grams (3.46 mmol, 1 eq) of C ₆ AzoC ₄ Br (MW 433.39) and triheptylamine (N (C ₇ H ₁₅ ) ₃ ) (MW 311. 59) 3.23 grams (10.37 mmol, 3 eq) was added. 50 ml of acetonitrile was added thereto, and the mixture was refluxed for 72 hours under an argon atmosphere (the system during heating was uniform). After returning the reaction solution to room temperature, the solvent was distilled off to obtain a dark red oil. Then, when this oil was dropped into 200 ml of hexane, a dark red viscous solid was precipitated. The supernatant hexane was removed, a small amount of toluene was added thereto, and the mixture was added dropwise again to 200 ml of hexane. A yellow powder was obtained and collected by vacuum filtration. After drying under reduced pressure, it was dissolved again in a small amount of toluene and added dropwise to 200 ml of hexane. The obtained powder was collected by vacuum filtration and dried to obtain 1.76 g (2.36 mmol) of a yellow powder.

All protons were assigned from the 1H-NMR spectrum measurement result of the obtained yellow powder. Moreover, the molecular ion peak was confirmed by MALDI-TOF-MS of yellow powder. The result of elemental analysis of the yellow solid was consistent with the composition of C ₆ AzoC ₄ N (C ₇ H ₁₅ ) ₃ ⁺ Br ⁻ . As a result, it was judged that C ₆ AzoC ₄ N (C ₇ H ₁₅ ) ₃ ⁺ Br ⁻ was synthesized.

Next, a change in absorption spectrum when the trans isomer of C ₆ AzoC ₄ N (C ₇ H ₁₅ ) ₃ ⁺ Br ⁻ (hereinafter abbreviated as “azobenzene compound” in this example) of this example is irradiated with ultraviolet light. And the result of having measured the absorption spectrum change at the time of irradiating visible light to the cis body of the azobenzene compound of a present Example is demonstrated based on FIG. 4, FIG. The absorption spectrum was measured at 25 ° C. in a 25 μM methanol solution using a cell having an optical path length of 1 cm.

  FIG. 4 shows the results of recording the change in absorbance every 5 seconds when the trans form of the azobenzene compound is irradiated with ultraviolet light of 365 nm for 40 seconds. The upper part of FIG. 4 shows the change of the absorption spectrum when the trans form of the azobenzene compound is irradiated with ultraviolet light, and the lower part of FIG. 4 shows the change of the absorbance at 356 nm.

  As shown in the upper part of FIG. 4, in the absorption spectrum before irradiation with ultraviolet light, a peak having a large absorbance appears in the vicinity of 356 nm derived from the trans form of the azobenzene compound. In the absorption spectrum after 40 seconds from irradiation with ultraviolet light, the absorbance near 356 nm decreases, and the absorbance near 448 nm derived from the cis isomer of the azobenzene compound increases. From this change in the absorption spectrum, it is clear that the trans form of the azobenzene compound of this example is changed to a cis form by irradiating with ultraviolet light.

  In addition, as shown in the lower part of FIG. 4, the absorbance at 356 nm derived from the trans form of the azobenzene compound rapidly decreases until about 20 seconds have elapsed after the start of irradiation with ultraviolet light (365 nm). It is gradually decreasing.

  FIG. 5 shows changes in absorbance when a cis isomer of an azobenzene compound is irradiated with visible light of 480 nm for 120 seconds, every 5 seconds until 30 seconds elapse, every 10 seconds from 30 seconds to 60 seconds, and 60 seconds elapse. After that, the results recorded every 20 seconds are shown. The upper part of FIG. 5 shows the change in the absorption spectrum when the cis isomer of the azobenzene compound is irradiated with visible light, and the lower part of FIG. 5 shows the change in the absorbance at 356 nm.

  As shown in the upper part of FIG. 5, in the absorption spectrum before irradiation with visible light, a peak having a large absorbance appears at around 448 nm derived from the cis isomer of the azobenzene compound. In the absorption spectrum after 120 seconds from irradiation with visible light, the absorbance near 448 nm decreases, and the absorbance near 356 nm derived from the trans form of the azobenzene compound increases. From the change in the absorption spectrum, it is clear that the cis isomer of the azobenzene compound of this example is changed to the trans isomer when irradiated with visible light.

  In addition, as shown in the lower part of FIG. 5, the absorbance at 356 nm derived from the trans form of the azobenzene compound increases rapidly until about 60 seconds have elapsed since the start of irradiation with visible light (480 nm), and thereafter It is increasing slowly.

  Next, the result of observing the azobenzene compound of the present example under the crossed Nicols condition of a polarizing microscope (POM) will be described with reference to FIGS. The POM image before irradiating the azobenzene compound trans isomer with ultraviolet light in FIG. 6 indicates that the azobenzene compound is in a crystalline state. Moreover, in the POM image after irradiating the trans form of the azobenzene compound shown in FIG. 7 with ultraviolet light, a dark field is observed in the central portion, and the portion irradiated with ultraviolet light in the crystalline azobenzene compound is in a liquid state. It has been shown. Moreover, in the POM image after irradiating the cis-isomer of the azobenzene compound shown in FIG. 8 with visible light, it can be confirmed that the portion observed as a dark field in FIG. .

(Other embodiments)
As mentioned above, although embodiment of this invention was described, this invention is not limited to this, Unless it deviates from the range described in each claim, it is not limited to the wording of each claim, and those skilled in the art Improvements based on the knowledge that a person skilled in the art normally has can be added as appropriate to the extent that they can be easily replaced.

  For example, in the above embodiment, an example in which the azobenzene compound of the present invention is used as a heat medium of a heat pump system has been described. However, the azobenzene compound may be used for applications other than the heat medium of the heat pump system.

  In the above embodiment, an example in which a heat pump system using an azobenzene compound as a heat medium is used for room heating has been described, but the present invention is not limited to this, in an environment where there are a low temperature side and a high temperature side, A heat pump system using an azobenzene compound as a heat medium can be used for other applications as long as the structure absorbs heat on the low temperature side and dissipates heat on the high temperature side.

  Moreover, although the said embodiment demonstrated the example which enclosed and used the azobenzene compound in the microcapsule, you may use an azobenzene compound not only in this but in a different aspect.

DESCRIPTION OF SYMBOLS 10 Circulation path | route 11 Low temperature side heat exchanger 12 High temperature side heat exchanger 13 Circulation pump

Claims (6)

An azobenzene compound represented by the general formula (1), which undergoes a cis-trans isomerization reaction by light irradiation.
In general formula (1),
Y: N or CH.
R _{1 to} R ₃ : a linear or branched alkyl group having 1 to 12 carbon atoms.
_{R 4: (OCH 2 CH 2} ) n ( where n is an integer of 1 to _{3), (OCH 2 CH 2 CH} 2) n ( where n is an integer of 1 to _{3), R 10, O-R} 10, NHR ₁₀ , N (R ₁₀ ) (R ₁₁ ), COOR ₁₀ or CONHR ₁₀ .
R ₁₀ and R ₁₁ are linear or branched alkyl groups having 1 to 12 carbon atoms.
R ₉ : CH ₃ (OCH ₂ CH ₂ ) _n O (where n is an integer of 1 to 3), CH ₃ (OCH ₂ CH ₂ CH ₂ ) _n O (where n is an integer of 1 to 3), R ₁₀ , R ₁₀ O, R ₁₀ NH, (R ₁₀ ) (R ₁₁ ) N, R ₁₀ COO or R ₁₀ CONH.
R _{5 to} R ₈ are any one of H, F, R ₁₄ , OR _{14, and} N (R ₁₄ ) ₂ .
R ₁₄ is any one of H, CH ₃ , C ₂ H ₅ , C ₃ H ₇ or i-C ₃ H ₇ .
X ⁻ : Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CH ₃ (CH ₂ ) _n SO ₃ ⁻ (where n is an integer of 0 to 2), TsO ⁻ , (YSO ₂ ) ₂ N ^- (where _{Y = F, CF 3, C} 2 F 5), (NC) 2 N - is either.   2. The azobenzene compound according to claim 1, wherein the azobenzene compound is transformed into a cis form by irradiating the trans form with ultraviolet light, and transformed into a trans form by irradiating the cis form with visible light. The melting point of the cis isomer is lower than the melting point of the trans isomer,
In the temperature range higher than the melting point of the cis isomer and lower than the melting point of the trans isomer, the solid phase trans isomer is transformed into a liquid phase cis isomer by irradiation with ultraviolet light, and the cis isomer is transformed into a solid phase trans isomer by visible light irradiation. The azobenzene compound according to claim 2, which changes. A circulation circuit (10) in which the heat medium containing the azobenzene compound represented by the general formula (1) circulates inside and is disposed across the low temperature side and the high temperature side;
A low temperature side heat exchanger (11) provided on the low temperature side in the circulation circuit (10) and transferring heat from the outside to the heat medium;
A high temperature side heat exchanger (12) provided on the high temperature side in the circulation circuit (10) and releasing heat from the heat medium to the outside;
The heat pump system, wherein the azobenzene compound is changed to a cis form by irradiation of the trans form with ultraviolet light, and is changed to a trans form by irradiation of visible light to the cis form.
In general formula (1),
Y: N or CH.
R _{1 to} R ₃ : a linear or branched alkyl group having 1 to 12 carbon atoms.
_{R 4: (OCH 2 CH 2} ) n ( where n is an integer of 1 to _{3), (OCH 2 CH 2 CH} 2) n ( where n is an integer of 1 to _{3), R 10, O-R} 10, NHR ₁₀ , N (R ₁₀ ) (R ₁₁ ), COOR ₁₀ or CONHR ₁₀ .
R ₁₀ and R ₁₁ are linear or branched alkyl groups having 1 to 12 carbon atoms.
R ₉ : CH ₃ (OCH ₂ CH ₂ ) _n O (where n is an integer of 1 to 3), CH ₃ (OCH ₂ CH ₂ CH ₂ ) _n O (where n is an integer of 1 to 3), R ₁₀ , R ₁₀ O, R ₁₀ NH, (R ₁₀ ) (R ₁₁ ) N, R ₁₀ COO or R ₁₀ CONH.
R _{5 to} R ₈ are any one of H, F, R ₁₄ , OR _{14, and} N (R ₁₄ ) ₂ .
R ₁₄ is any one of H, CH ₃ , C ₂ H ₅ , C ₃ H ₇ or i-C ₃ H ₇ .
X ⁻ : Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CH ₃ (CH ₂ ) _n SO ₃ ⁻ (where n is an integer of 0 to 2), TsO ⁻ , (YSO ₂ ) ₂ N ^- (where _{Y = F, CF 3, C} 2 F 5), (NC) 2 N - is either.   The heat pump system according to claim 4, wherein the azobenzene compound is changed to a cis form by irradiating the trans form with ultraviolet light, and is changed to a trans form by irradiating the cis form with visible light.   In the azobenzene compound, the melting point of the cis isomer is lower than the melting point of the trans isomer, and in the temperature range higher than the melting point of the cis isomer and lower than the melting point of the trans isomer, the solid phase trans isomer is irradiated with ultraviolet light. 6. The heat pump system according to claim 5, wherein the heat pump system changes to a solid cis form by irradiation with visible light to the cis form.