JP2002332480A - Photochromic compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photochromic compound capable of reversibly and photoresponsively controlling color changes and viscosities, and requiring no UV irradiation to control nor mixing of a metal ion to stabilize a merocyanine structure. SOLUTION: This photochromic compound is prepared by dissolving a copolymer having (a) and (b) expressed in formula (1) (wherein R1 , R2 , R3 and R4 express each independently H or methyl; R5 expresses an alkyl or an amide; R6 expresses a fluoronated alkyl; X expresses C, N or S; Y expresses O or S) in a fluoronated alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photochromic compound, and more particularly, to a photochromic compound capable of reversibly controlling viscous resistance together with color by light irradiation.

[0002]

2. Description of the Related Art Various compounds exhibiting reversible changes in elastic modulus and solution viscosity by applying a voltage and changing the direction of an electric field have been proposed. A damper that absorbs vibrations in a use environment, a power transmission device, It is used for various applications such as a pressure converter. On the other hand, as a phenomenon in which a compound can take the form of two reversible isomers without the need for a device or operation such as application of a voltage as described above, photochromism in which the compound is reversibly discolored by irradiation of light to the compound is mentioned. Is mentioned. Examples of the compound exhibiting photochromism (hereinafter, referred to as a photochromic compound) include a compound utilizing a merocyanine structure of a spiropyran or spirooxazine molecule. According to spiropyran and spirooxazine molecules, it has been reported that the viscosity as well as the color change by light irradiation (M. Irie, A. Menj).
u, K. Hayashi, Macromolecule
s, 1981, 12, 1176 and A.I. Menju,
K. Hayashi, M .; Irie, Macromol
ecules, 1981, 14, 755). Irradiation with ultraviolet light is necessary for reversible control of the photoresponsiveness of these photochromic compounds, and the degradation of the photochromic compound by the ultraviolet light is by-produced. Further, there are problems that the equipment is large due to the ultraviolet light irradiation device and that the irradiation cost is high. Therefore, as a technique for stabilizing the merocyanine structure without using ultraviolet light, complex formation with a metal ion has been frequently used.

[0003]

The formation of a complex with a metal ion is accomplished by dissolving spiropyran or spirooxazine in a solvent and forming the merocyanine structure of the spiropyran or spirooxazine molecule with a metal ion such as copper or lead in the solvent. It is stabilized by complex formation. However, the disposal of these metals after the product disposal is complicated, and there is a problem in terms of environmental safety such as reduction of industrial waste and prevention of harmful metal outflow. Therefore, an object of the present invention is to provide a photochromic compound which can reversibly control the photoresponsiveness of the viscosity as well as the discoloration, does not require irradiation with ultraviolet light for control, and does not contain a metal ion for stabilizing the merocyanine structure. It is in.

The present inventor has disclosed a copolymer having a spiropyran segment or a spirooxazine segment and a fluorinated alcohol segment, wherein the merocyanine structure and the fluorinated alcohol segment in the copolymer are responsive to visible light irradiation. The reversible control of the occurrence of intramolecular hydrogen bonds with the fluorinated alcohol solution in which this photoresponsive copolymer is dissolved can be controlled by the wavelength of light (visible light and ultraviolet light) that irradiates this solution. A copolymer which can be reversibly adjusted by strength and strength was synthesized, and various conditions were established to solve the above-mentioned problem.

[0005]

In order to achieve the above object, the present invention provides a method comprising dissolving a copolymer having essential segments (a) and (b) represented by the following formula (1) in a fluorinated alcohol. The gist of the present invention is a photochromic compound.

Embedded image However, in the formula (1), R ₁ , R ₂ , R ₃ and R ₄ are each independently H or CH ₃ , R ₅ is an alkyl group or an amide group, R ₆ is a fluorinated alkyl group, X is a carbon atom, a nitrogen atom or a sulfur atom, and Y is an oxygen atom or a sulfur atom.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The photochromic compound of the present invention comprises a segment (a) represented by the above formula (1), ie, a spiropyran segment or a spirooxazine segment, and a segment (b), ie, a fluorinated alcohol segment, The essential copolymer is a solute,
This is a solution in which fluorinated alcohol is dissolved as a solvent. In the formula (1), R ₁ , R ₂ , R ₃ and R ₄ are each independently H or CH ₃ , and the polymer may be an acrylate copolymer or CH ₃ if R ₁ and R ₂ are H. For example, it is a methacrylate polymer.

R ₅ is an alkyl group or an amide group.
R ₅ is specifically exemplified by a methyl group, an ethyl group, a dodecyl group and the like. R ₆ is a fluorinated alkyl group in which at least one hydrogen atom of the alkyl group has been replaced by fluorine. For R ₆ , hydrogen at a position close to the hydroxyl group of the fluorinated alcohol segment is preferably fluorinated, such as — (CF ₂ ) ₆ CH ₂ CH ₃ , and more preferably a perfluoroalkyl group. Specific examples of R ₆ include a trifluoromethyl group, a pentafluoroethyl group, a perfluorooctyl group, a perfluorododecyl group, and the like. X is a carbon atom, a nitrogen atom or a sulfur atom, and Y is an oxygen atom or a sulfur atom. The polymerization of the (a) segment and the (b) segment may be block polymerization or alternate polymerization, and is not particularly limited. Hereinafter, the case where X is a carbon atom and Y is an oxygen atom, that is, the case where the copolymer has a spiropyran segment as the segment (a) due to the merocyanine structure will be described.

[0008] The spiropyran segment in the above copolymer has a photoresponsive property of reversibly isomerizing by irradiation with light into an electrically neutral spiropyran structure and a merocyanine structure having a zwitterion in the molecule. Have.

When the spiropyran segment in the copolymer has a merocyanine structure, an intramolecular hydrogen bond occurs between the merocyanine structure and the fluorinated alcohol segment. The intramolecular hydrogen bond is canceled when the merocyanine structure returns to the spiropyran structure. Intramolecular hydrogen bonding causes discoloration of the photochromic compound and changes in the viscous resistance of the solution containing the photochromic compound.

FIG. 1 shows an embodiment of the present invention.
The UV-visible absorption spectra of a fluorinated alcohol solution of a methacrylate copolymer of spiropyran and a fluorinated alcohol (solid line) and a fluorinated alcohol solution of this spiropyran monomer (dashed line) at high viscosity in a dark place are shown. Show. In FIG. 1, 1 ′, 3 ′, 3′-trimethyl-6- (methacryloyloxy) spiro (2H-) is a methacrylate of spiropyran (hereinafter referred to as SPMA).
1-benzopyran-2,2'-indole)
3-Perfluorooctyl-2-hydroxypropyl methacrylate is used as methacrylate of fluorinated alcohol (hereinafter referred to as FHMA), and 1,1,1,3,3,3 −
Hexafluoropropan-2-ol (hereinafter, referred to as HFP) was used.

The HFP solution of the copolymer is colored in a dark place because spiropyran segments in the copolymer are isomerized to form a merocyanine structure in a dark place. However, the color is orange which is slightly different in color from the HFP solution of the spiropyran monomer. That is, as shown in FIG. 1, an absorption band on the longer wavelength side in the visible region, which does not exist in the spiropyran monomer before polymerization, appears in the absorption spectrum of the copolymer. At this time, as shown in the following formula (2), an intramolecular hydrogen bond is formed between the oxygen ion of the merocyanine structure opened in the copolymer and the hydrogen of the hydroxyl group of the fluorinated alcohol segment in the same molecule. Is occurring. In addition, in Formula (2), n shows the molar ratio of a segment, and is 0 <n <1.

Embedded image

A visible light (> 420 nm) is externally irradiated to the copolymer solution in the dark place. Then, since the merocyanine structure is closed and isomerized into a spiropyran structure, the absorption band in the visible region disappears, and the copolymer solution becomes colorless and transparent. The fluorinated alcohol segment in the copolymer, which had previously been hydrogen-bonded in the same molecule, is now hydrogen-bonded to the fluorinated alcohol segment in another molecule, forming a cross-linked structure and the copolymer itself. Gels. Since the gelled copolymer floats in the fluorinated alcohol solvent, the viscosity of the entire solution decreases.

When the irradiation of visible light is stopped and the copolymer solution is placed in a dark place, the spiropyran segments in the copolymer again have a merocyanine structure and form hydrogen bonds with fluorinated alcohol segments in the same molecule. Then, the hydrogen bond between the fluorinated alcohol segments of the crosslinked structure is broken. At this time, the copolymer solution is colored orange again, and the gelled copolymer is dissolved again in the solvent, and the viscosity of the whole solution increases.

In the above, when the device is placed in a dark place without irradiating the visible light, the irradiation with the ultraviolet light may be used instead. I do.

The photoresponsiveness of the above-described copolymer solution corresponds to the light irradiation intensity as well as the light irradiation time. For example, when irradiating an orange copolymer solution in a dark place with visible light, it is possible to control the solution to be colorless and transparent and decrease the viscosity by adjusting the irradiation intensity and irradiation time of the visible light.

FIG. 2 is a graph showing the time-dependent changes in coloring and kinematic viscosity represented by absorbance at 550 nm when the same solution used in FIG. 1 is left in the dark after irradiation with visible light. The time-dependent change of the spiropyran segment from the spiropyran structure to the merocyanine structure in the copolymer is consistent with the time-dependent change of the kinematic viscosity. It can be seen that the viscosity of the polymer solution can be controlled.

The fluorinated alcohol solution of the copolymer is preferred because the higher the concentration of the solute, the greater the change in viscosity resistance. However, when the content of the spiropyran segment in the copolymer is too small, the solubility of the copolymer in the fluorinated alcohol solvent is reduced even in a dark place. The content of the spiropyran segment corresponds to, for example, the value n of the molar ratio of spiropyran segment / (spiropyran segment + fluorinated alcohol segment) in the copolymer in the case of the above formula (2). The content of the spiropyran segment in the copolymer is appropriately selected according to the solubility of the copolymer in a fluorinated alcohol solvent, required characteristics, and the like. For example, HF exemplified in the above embodiment
In the case of the P solution, the content of the spiropyran segment in the copolymer is preferably at least 70 mol% in order to dissolve the copolymer in HFP at a high concentration.

On the other hand, in order to provide intramolecular hydrogen bonds from the fluorinated alcohol segment, a certain amount of the fluorinated alcohol segment is required, so that the content of the spiropyran segment in the copolymer is 90 mol% or less. Is preferred.

The fluorinated alcohol as the solvent is preferably one having a high solubility of the solute copolymer, one having a high hydrogen bond donating property, one having a high response speed to light, and the like. Specifically, in addition to HFP, for example, 2,2,2-trifluoroethanol, 2-fluoroethanol and the like can be mentioned.
Among them, HFP is preferred in that the copolymer has high solubility and a wide range of change in viscosity, and 2,2,2-trifluoroethanol is preferred in terms of a high response speed to light.

As described above, as SPMA, 1 ', 3', 3'-
Trimethyl-6- (methacryloyloxy) spiro (2
H-1-benzopyran-2,2'-indole), FH
The case where 3-perfluorooctyl-2-hydroxypropyl methacrylate is used as MA has been described. However, similar photoresponsiveness can be obtained with photochromic compounds using other spiropyrans, other fluorinated alcohols or acrylates in formula (1). Have. Further, spiropyran is a case where X in the segment (a) in the formula (1) is a carbon atom and Y is an oxygen atom, but the same applies to other combinations of X and Y. Furthermore, in addition to the segments of (a) and (b) of the formula (1), the copolymer may contain other segments as necessary. For this, for example, a compound having an ethylenically unsaturated group can be used.

[0021]

The present invention will be specifically described below with reference to examples. The present invention is not limited by the embodiments. (Example 1) Spiropyran methacrylate (SPMA)
Synthesis of 1 ′, 3 ′, 3′-trimethyl-6-hydroxyspiro (2H-1-benzopyran-2,2′-indole) 4.72 g (0.0161 mol) (ACRO
S ORGANICS Co., Ltd., purity 99%, FW 293.37, product number 42192-0050) was dissolved in 28 ml of toluene (Kanto Chemical Co., Ltd., special grade, purity 99.5%, boiling point 110.625 ° C.). Methacrylic acid chloride (ACROS ORGANICS,
1.84 g) 760 mmHg boiling point 95-96 ° C)
(0.0176 mol) was dissolved in 14 ml of toluene (same as above). Separately, triethylamine (hereinafter referred to as TEA)
(Wako Pure Chemical Industries, 99% purity, product number 202-02646)
79 g (0.0114 mol) was prepared. In addition, 5 units were prepared using a 100 ml solution of 400 ml of pure water of 400 ml of ammonia (manufactured by Kanto Chemical Co., Ltd., purity: 28.0 to 30.0%, product number: 01266-00). The toluene solution of spiropyran obtained above and the above TEA are charged into a two-necked eggplant flask, a ball-in condenser is provided in one of the two-necked flask, and a cylindrical separatory funnel is provided in the other. Was attached. 60 two-necked flasks
After the toluene solution of methacrylic acid chloride was dripped little by little with a cylindrical separating funnel while keeping the temperature at ℃,
The reaction was performed for 24 hours. The hydrochloric acid generated in this reaction was neutralized with TEA. After 24 hours, in order to remove unreacted methacrylic acid chloride and TEA from the reaction solution, the reaction solution was diluted with 100 ml of toluene, then transferred into a separating funnel, and 1 unit of the above aqueous ammonia solution was added. The separating funnel was shaken and allowed to stand to take out the lower aqueous ammonia solution. One unit of the remaining aqueous ammonia solution was added, and the separation was repeated in a similar manner five times in total. 100 ml of pure water was added instead of the aqueous ammonia solution, and the separation was repeated a total of 5 times until the pH reached 7. The toluene in the upper layer of the separating funnel was evaporated by an evaporator and then dried under reduced pressure. The brown solid thus obtained was dissolved in dichloromethane and subjected to column chromatography to separate impurities. The column was silica gel (manufactured by Kanto Chemical Co., Inc., product number: 9385-4M, Rf: 0.
86) The developing solvent used dichloromethane. The liquid discharged from the column was evaporated with an evaporator to remove dichloromethane, and then dried under reduced pressure to obtain spiropyran methacrylate (SPMA) monomer, 1 ′, 3
', 3'-Trimethyl-6- (methacryloyloxy)
1.11 g (yield 23.5%) of spiro (2H-1-benzopyran-2,2'-indole) was obtained.

Synthesis of copolymer: 1 ′, 3 ′, 3′-Trimethyl-6- (methacryloyloxy) spiro (2H-1-benzopyran-2,2) of the SPMA monomer obtained above.
'-Indole) (molecular weight 361.44)
g (1.38 mmol) were prepared. In addition, 3-perfluorooctyl-2-hydroxypropyl methacrylate (molecular weight 562.22) was used as methacrylate (FHMA) of fluorinated alcohol in an equimolar ratio of 780 to SPMA.
mg (1.39 mmol). Besides, DMSO
8 ml, 7.6 mg of polymerization initiator AIBN (S
1/60 of the total number of moles of PMA and FHMA), 15 mg of polymerization inhibitor hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd., 99.0%, product number H0186), and pure water were prepared.

First, the SPMA and the FHMA are respectively assigned to the DMS
The two solutions obtained by dissolving 4 ml of O
The mixture was placed in a two-necked flask fitted with a bulb cooler in one port and a Pasteur pipette with a rubber stopper in the other port. Dry nitrogen was flowed into the flask through a Pasteur pipette for 20 minutes to remove moisture and air from the inside of the apparatus. Adjust the temperature of the flask to 60 in an oil bath.
After raising the temperature to ° C and adding a polymerization initiator and reacting for 2 hours, the reaction was stopped by adding a polymerization inhibitor.

The reaction product in the flask was dropped into a large amount of pure water little by little to precipitate and purify. The precipitate was filtered off with a filter paper, and further dried under reduced pressure to obtain 1 ', 3', 3'-trimethyl-6- (methacryloyloxy) spiro (2H
Copolymer of -1-benzopyran-2,2'-indole) and 3-perfluorooctyl-2-hydroxypropyl methacrylate (P (SPMA-FHMA)) 8
90 mg (69.5% yield) was obtained. When the molar ratio of each segment in this copolymer was calculated from the integral ratio of each site by 1H-NMR measurement, SPMA: FHMA was 71:29, that is, the spiropyran segment content was 71 mol%.

P (SPMA-FHMA) 3 obtained above
3 mg was dissolved in 10 ml of 1,1,1,3,3,3-hexafluoropropan-2-ol (HFP) as a solvent to prepare a 8.0 mM HFP solution. The viscosity and ultraviolet-visible absorption spectrum of this HFP solution were measured as follows in a dark room temperature condition.

(Viscosity measurement) The orange P (S
An HFP solution of PMA-FHMA) was left in the dark for 24 hours to equilibrate. Next, irradiation was performed with visible light from a xenon lamp from which ultraviolet light was removed through a filter for about 10 minutes, and then the irradiation was terminated. At this time, the solution was sufficiently light in color and nearly colorless and transparent. The viscosity of the solution immediately after the end of the irradiation was measured using an Ubbelohde viscometer (manufactured by SIBATA; use viscosity range of 1 to 5 cSt), and the change with time of the viscosity was measured every 10 minutes for a total of 60 minutes after the end of the irradiation.

(Spectrum measurement) An HFP solution of the copolymer P (SPMA-FHMA) prepared above
After allowing to stand for 4 hours to reach an equilibrium state, an ultraviolet-visible absorption spectrum was measured. For comparison, the SPMA monomer 1 ′, 3 ′, 3′-trimethyl-6- (methacryloyloxy) spiro (2H-1-benzopyran-2,2)
The UV-visible absorption spectrum of a 8.0 mM HFP solution of '-indole) was also measured. FIG. 1 shows the absorption spectrum of the copolymer solution by a solid line and the absorption spectrum of the monomer solution by a broken line.

Separately, the HFP solution whose viscosity was measured above was placed in a quartz cell having an optical path length of 1 mm, and the visible light obtained by removing ultraviolet light from a xenon lamp through a filter until the solution became almost colorless and transparent was filtered. Irradiated for 1 minute. Immediately after the completion of the irradiation, the time-lapse measurement of the ultraviolet-visible absorption spectrum was performed every 1 minute for a total of 60 minutes. FIG. 2 shows a time-dependent change in absorbance (right axis) at a wavelength of 550 nm in the ultraviolet-visible absorption spectrum with a broken line, and a time-dependent change in viscosity (left axis) measured above with a solid line.

[0029]

According to the photochromic compound of the present invention, colorlessness and viscosity decrease upon irradiation with visible light, color development and viscosity increase upon stopping irradiation with visible light, and wide discoloration and change in viscosity without the need for ultraviolet light irradiation. Photoresponsiveness can be controlled reversibly. Also, because it does not mix metal ions, a technique frequently used for stabilizing the merocyanine structure,
Easy disposal after use.

[Brief description of the drawings]

FIG. 1 shows a fluorinated alcohol solution (solid line) of a methacrylate copolymer of spiropyran and fluorinated alcohol (P (SPMA-FHMA)), which is an example of the photochromic compound of the present invention, and its spiropyran monomer. It is a graph which shows the ultraviolet-visible absorption spectrum at the time of the high viscosity in the dark place with the fluorinated alcohol solution (broken line) of SPMA.

FIG. 2 is a graph showing the time-dependent change of the fluorinated alcohol solution of the copolymer in FIG. 1 after irradiation with visible light in a dark place, in which the solid line indicates kinematic viscosity (left axis), and the dashed line indicates the viscosity at 550 nm. The coloring (right axis) indicated by the absorbance is shown.

Claims (4)

[Claims] 1. A photochromic compound characterized in that a copolymer comprising (a) and (b) represented by the following formula (1) as essential segments is dissolved in fluorinated alcohol. Embedded image (However, in the formula (1), R ₁ , R ₂ , R ₃ and R ₄ are each independently H or CH ₃ , R ₅ is an alkyl group or an amide group, and R ₆ is a fluorinated alkyl group. , X is a carbon atom, a nitrogen atom or a sulfur atom, and Y is an oxygen atom or a sulfur atom.) 2. The copolymer according to claim 1, wherein the copolymer is 1 ′, 3 ′, 3′-trimethyl-6- (methacryloyloxy) spiro (2H
-1-benzopyran-2,2'-indole) and 3-
The photochromic compound according to claim 1, which is a copolymer with perfluorooctyl-2-hydroxypropyl methacrylate. 3. The method according to claim 2, wherein the fluorinated alcohol is 1,1,1,
3. The photochromic compound according to claim 1, which is 3,3,3-hexafluoropropan-2-ol. 4. The photochromic compound according to claim 3, wherein the content of the spiropyran segment in the copolymer is 70 mol% to 90 mol%.