Preparation method and application of photochromic material

Abstract

The present invention belongs to the technical field of organic solid-state photochromic materials, and relates to a preparation method and application of photochromic materials. By introducing porous materials into the photochromic system, the free volume of the photochromic molecules in the solid state and their color change rate are increased, and Tb is introduced by complexation reaction and esterification reaction. 3+ Modifying the HOFs framework material with ester groups not only improves the stability of the framework, but also improves the photochromic properties of spiropyran. Compared with the unmodified HOFs framework material, it has a faster light response rate and better photochromic properties, and has better development prospects in the field of anti-counterfeiting. At the same time, it has better information storage encryption functions than most current information storage encryption materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic solid-state photochromic materials, and in particular relates to a preparation method and application of a photochromic material. Background Art

[0002] Spiropyran compounds are a type of stimuli-responsive color-changing material that can undergo an isomerization transition from a closed-ring state (SP) to an open-ring state (MC) under the stimulation of ultraviolet light, accompanied by a color change. They have many advantages such as low cost, fast reading speed, and reusability, and are widely used in the anti-counterfeiting field.

[0003] Current research shows that solid-state spiropyran molecules are difficult to photochromic. The main reason is that in the solid state, spiropyran is tightly packed and there is insufficient spatial volume for it to undergo the ring-opening-closing isomerization process, resulting in poor color change performance under ultraviolet light, which greatly limits its application prospects in the anti-counterfeiting field.

[0004] Therefore, how to improve the solid-state photochromic properties of spiropyran while making its color change range wide and better broaden the application of photochromic materials in anti-counterfeiting and information storage encryption is an important technical problem that researchers in this field urgently need to solve. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention proposes a preparation method and application of a photochromic material. 3+ Modifying the framework material with ester groups not only improves the stability of the framework but also enhances the photochromic properties of spiropyran.

[0006] To achieve the above objectives, the present invention provides a modified HOFs framework material, which is a HOFs framework material modified with lanthanide elements and / or double bonds.

[0007] On the other hand, the present invention also provides a method for preparing the modified HOFs framework material, comprising:

[0008] The method of lanthanide element modification is as follows: Tb-HOFs framework material is prepared by complexation reaction between lanthanum salt and HOFs framework material;

[0009] The double bond modification method is as follows: using esterification reaction to modify HOFs framework material through olefin alcohol to obtain HOFs-olefin framework material;

[0010] The method of co-modification of lanthanide elements and double bonds is: first, lanthanum salt and HOFs framework material are complexed to prepare Tb-HOFs framework material, and then Tb-HOFs framework material is modified by olefin alcohol through esterification reaction to obtain Tb-HOFs-olefin framework material.

[0011] Furthermore, the HOFs framework material is assembled through the ligand 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TATB).

[0012] Furthermore, the specific steps of the lanthanide element modification method are: dispersing the HOFs framework material in an ethanol solution, adding lanthanum salt to the ethanol solution, stirring and centrifuging to collect the white solid, using anhydrous ethanol and acetone to centrifuge and wash three times respectively, soaking in a dichloromethane solution (CH2Cl2) for three days, and finally centrifuging and vacuum drying to obtain the Tb-HOFs framework material.

[0013] Preferably, the mass ratio of the HOFs framework material to the lanthanum salt is 4-6:6-9; the mass volume ratio of the HOFs framework material to ethanol is 20-30 mg:6-9 mL.

[0014] Preferably, the ethanol solution is anhydrous ethanol.

[0015] Preferably, the stirring speed is 1000-1200 r / min and the stirring time is 12-15 h.

[0016] Furthermore, the double bond modification method specifically comprises the following steps: ultrasonically disrupting the HOFs framework material to obtain an assembled framework HOFs, adding 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), activating the carboxyl group, adding olefin alcohol, dissolving it in a mixture of water and anhydrous ethanol, stirring the reaction, and then centrifuging the reaction solution to collect the reaction product, washing the reaction product three times each with anhydrous ethanol and acetone, and drying it in a vacuum drying oven to obtain the HOFs-olefin framework material.

[0017] Preferably, the mass ratio of the assembled framework HOFs to 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is 20-40:1-2; the mass volume ratio of the assembled framework HOFs to olefin alcohol is 4-8 mg:5-10 μL; and the volume ratio of the olefin alcohol to the mixed solution is 50-100 μL:13-26 mL.

[0018] It is worth noting that ultrasonic disruption can expose more carboxyl groups in the HOFs framework material for reaction between lanthanides and olefin alcohols, so that the HOFs framework material can be modified with more lanthanides and double bonds, thereby improving the photochromic properties of the material.

[0019] Preferably, the volume ratio of water to anhydrous ethanol in the mixed solution is 3-6:10-20.

[0020] Preferably, the ultrasonic interruption temperature is room temperature and the time is 20-30 minutes.

[0021] Preferably, the stirring reaction time is 12-15 hours.

[0022] Furthermore, the specific steps of the method for co-modification of lanthanide elements and double bonds are: replacing the HOFs framework material in the specific steps of the above double bond modification method with a Tb-HOFs framework material, and keeping other conditions and parameters the same, to prepare a Tb-HOFs-olefin framework material.

[0023] Furthermore, the lanthanum salt is Tb(NO3)3·6H2O; and the olefin alcohol is 5-hexen-1-ol.

[0024] On the other hand, the present invention also provides a use of the modified HOFs framework material in preparing a photochromic material.

[0025] On the other hand, the present invention also provides a photochromic material, which uses the modified HOFs framework material as a carrier and a stimulus-responsive color-changing material as a load.

[0026] On the other hand, the present invention also provides a method for preparing the above-mentioned photochromic material, comprising preparing a stimuli-responsive color-changing material into a solution, uniformly mixing the modified HOFs framework material with the stimuli-responsive color-changing material solution, allowing the mixture to stand, and drying to obtain the photochromic material.

[0027] Furthermore, the mass ratio of the stimulus-responsive color-changing material to the modified HOFs framework material is 2-4:7-13.

[0028] Furthermore, the stimulus-responsive color-changing material is spiropyran; the solvent of the solution is toluene, and the concentration is 0.2 mol / L.

[0029] Preferably, the spiropyran is methylspiropyran.

[0030] On the other hand, the present invention also provides an application of the above-mentioned photochromic material in the field of information storage and encryption.

[0031] On the other hand, the present invention also provides an application of the above-mentioned photochromic material in the field of anti-counterfeiting.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects:

[0033] (1) The present invention introduces the lanthanide metal Tb into the HOFs framework material through complexation reaction and esterification reaction. 3+ and double bonds, modifying more free carboxyl groups in the HOFs framework materials, enhancing the stability of the HOFs framework materials and greatly improving the color-changing properties of spiropyran.

[0034] (2) The present invention uses Tb-HOFs framework material, HOFs-olefin framework material and Tb-HOFs-olefin framework material to adsorb spiropyran through a solution adsorption method, and loads the spiropyran molecules into the pores of the framework material, so that the densely stacked spiropyran molecules are dispersed, and the free volume of the spiropyran molecules is increased. At the same time, the spiropyran molecules have sufficient spatial freedom in the solid state to perform ring-opening-closing reactions, making the color change effect of the spiropyran more obvious, and significantly improving the solid-state photochromic performance of the spiropyran molecules.

[0035] (3) The photochromic material prepared by the present invention has a solid powder that undergoes significant changes in both physical color and fluorescent color within 30 seconds when irradiated with ultraviolet light of a wavelength of 365 nm. The physical color of the Tb-HOFs@SP material changes from white to pink, and the fluorescent color changes from orange to red; the physical color of the HOFs-olefin@SP and Tb-HOFs-olefin@SP materials changes from white to purple, and the fluorescent color changes from orange to red.

[0036] (4) While achieving photochromism, the present invention has a faster light response rate than unmodified frame materials, has better photochromic performance, has better development prospects in the field of anti-counterfeiting, and has better information storage encryption functions than most current information storage encryption materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0038] Figure 1 This is the ultraviolet absorption spectrum of the photochromic material prepared in Example 1 when irradiated with 365nm ultraviolet light for different times, and a graph showing the color change of the solid powder after irradiation with 365nm ultraviolet light for different times.

[0039] Figure 2 This is the fluorescence emission spectrum of the photochromic material prepared in Example 1 under 365nm ultraviolet light irradiation for different times and the solid fluorescence color change diagram after 365nm ultraviolet light irradiation for different times.

[0040] Figure 3 This is the ultraviolet absorption spectrum of the photochromic material prepared in Example 2 when irradiated with 365nm ultraviolet light for different times, and a graph showing the color change of the solid powder after irradiation with 365nm ultraviolet light for different times.

[0041] Figure 4This is the fluorescence emission spectrum of the photochromic material prepared in Example 2 under 365nm ultraviolet light irradiation for different times and the solid fluorescence color change diagram after 365nm ultraviolet light irradiation for different times.

[0042] Figure 5 This is the ultraviolet absorption spectrum of the photochromic material prepared in Example 3 when irradiated with 365nm ultraviolet light for different times, and the color change diagram of the solid powder after irradiation with 365nm ultraviolet light for different times.

[0043] Figure 6 This is the fluorescence emission spectrum of the photochromic material prepared in Example 3 under 365nm ultraviolet light irradiation for different times and the solid fluorescence color change diagram after 365nm ultraviolet light irradiation for different times.

[0044] Figure 7 This is the ultraviolet absorption spectrum of the photochromic material prepared in Comparative Example 1 after being irradiated with 365nm ultraviolet light for different times, and a graph showing the color change of the solid powder after being irradiated with 365nm ultraviolet light for different times.

[0045] Figure 8 This is the fluorescence emission spectrum of the photochromic material prepared in Comparative Example 1 under 365nm ultraviolet light irradiation for different times and the solid fluorescence color change diagram after 365nm ultraviolet light irradiation for different times.

[0046] Figure 9 This is the fluorescence emission spectrum of the Tb-HOFs framework material prepared in Example 1 that was successfully modified by lanthanide elements.

[0047] Figure 10 This is the infrared spectrum of the HOFs-olefin framework material prepared in Example 2 that was successfully modified with olefin alcohol.

[0048] Figure 11 This is the infrared spectrum of the Tb-HOFs-olefin framework material prepared in Example 3 that was successfully modified with olefin alcohol. DETAILED DESCRIPTION

[0049] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0050] In addition, for numerical ranges in the present invention, it is understood that each intervening value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or stated range, and any other stated value or intervening value in the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention.

[0052] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0053] The room temperature referred to in the present invention is the indoor temperature, which is well known to those skilled in the art and will not be described in detail here; it should be pointed out in particular that the room temperature referred to in the embodiments of the present invention is 25°C.

[0054] Example 1

[0055] Preparation of Tb-HOFs@SP photochromic material:

[0056] S1. Dissolve 1 g of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TATB) in 100 mL of N,N-dimethylformamide (DMF). Add 300 mL of deionized water to the solution. Stir at 1000 rpm for 12 h at room temperature, and collect the white solid by centrifugation.

[0057] S2. The collected white solid was washed three times with acetone by centrifugation, then immersed in a dichloromethane solution (CH2Cl2) for three days, and finally dried by centrifugation in a vacuum to obtain the HOFs framework material.

[0058] S3. Take 100 mg of HOFs framework material and disperse it in 30 mL of ethanol solution. Add 150 mg of Tb(NO3)3·6H2O to the ethanol solution and stir at 1000 r / min for 12 h. Collect the white solid by centrifugation and wash it three times with anhydrous ethanol and acetone respectively. The collected solid is further soaked in dichloromethane solution (CH2Cl2) for three days. Finally, dry it by centrifugation in a vacuum to obtain the Tb-HOFs framework material.

[0059] S4. Take 30 mg of methyl spiropyran and dissolve it in toluene solution to prepare a solution with a concentration of 0.2 mol / L. Use a dropper to evenly add the solution to 100 mg of Tb-HOFs framework material. Let it stand at room temperature for 3 hours and dry naturally to obtain Tb-HOFs@SP photochromic material.

[0060] Figure 1 This is the ultraviolet absorption spectrum of the Tb-HOFs@SP photochromic material prepared in Example 1 after being irradiated with 365nm ultraviolet light for different times, and the color change diagram of the solid powder after being irradiated with 365nm ultraviolet light for different times.

[0061] Figure 2 This is the fluorescence emission spectrum of the Tb-HOFs@SP photochromic material prepared in Example 1 under 365nm ultraviolet light irradiation for different times and the solid fluorescence color change diagram after 365nm ultraviolet light irradiation for different times.

[0062] Figure 9 This is the fluorescence emission spectrum of the Tb-HOFs framework material prepared in Example 1 that was successfully modified by lanthanide elements.

[0063] Example 2

[0064] Preparation of HOFs-olefin@SP photochromic materials:

[0065] S1. Dissolve 1 g of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TATB) in 100 mL of N,N-dimethylformamide (DMF). Add 300 mL of deionized water to the solution. Stir at 1000 rpm for 12 h at room temperature, and collect the white solid by centrifugation.

[0066] S2. The collected white solid was washed three times with acetone by centrifugation, then immersed in a dichloromethane solution (CH2Cl2) for three days, and finally dried by centrifugation in a vacuum to obtain the HOFs framework material.

[0067] S3. The powdered HOFs framework material was ultrasonically disrupted at room temperature for 20 min to obtain the assembled framework HOFs (40 mg). 2 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) was added to activate the carboxyl group. 50 μL of 5-hexen-1-ol was added and dissolved in a mixture of 3 mL of deionized water and 10 mL of anhydrous ethanol. The mixture was stirred at room temperature for 12 h.

[0068] S4. The reaction solution was centrifuged and washed three times with anhydrous ethanol and acetone respectively, and then dried in a vacuum drying oven to obtain a HOFs-olefin framework material.

[0069] S5. Take 30 mg of methyl spiropyran and dissolve it in toluene solution to prepare a solution with a concentration of 0.2 mol / L. Use a dropper to evenly add the solution to 100 mg of HOFs-olefin framework material. Let it stand at room temperature for 3 hours and dry naturally to obtain HOFs-olefin@SP photochromic material.

[0070] Figure 3 This is the ultraviolet absorption spectrum of the HOFs-olefin@SP photochromic material prepared in Example 2 after being irradiated with 365nm ultraviolet light for different times, and the color change diagram of the solid powder after being irradiated with 365nm ultraviolet light for different times.

[0071] Figure 4 This is the fluorescence emission spectrum of the HOFs-olefin@SP photochromic material prepared in Example 2 under 365nm ultraviolet light irradiation for different times and the solid fluorescence color change diagram after 365nm ultraviolet light irradiation for different times.

[0072] Figure 10 This is the infrared spectrum of the HOFs-olefin framework material prepared in Example 2 that was successfully modified with olefin alcohol.

[0073] Example 3

[0074] Preparation of Tb-HOFs-olefin@SP photochromic material:

[0075] S1. Dissolve 1 g of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TATB) in 100 mL of N,N-dimethylformamide (DMF). Add 300 mL of deionized water to the solution. Stir at 1000 rpm for 12 h at room temperature, and collect the white solid by centrifugation.

[0076] S2. The collected white solid was washed three times with acetone by centrifugation, then immersed in a dichloromethane solution (CH2Cl2) for three days, and finally dried by centrifugation in a vacuum to obtain the HOFs framework material.

[0077] S3. Disperse 100 mg of the HOFs framework material in 30 mL of ethanol solution. Add 150 mg of Tb(NO₃)₃·6H₂O to the ethanol solution, stir at 1000 rpm for 12 hours, and collect the white solid by centrifugation. Wash the solid three times with ethanol and acetone by centrifugation. Soak the solid in dichloromethane (CH₂Cl₂) for three days and finally dry it by centrifugation in a vacuum oven to obtain the Tb-HOFs framework material.

[0078] S4. The powdered Tb-HOFs framework material was ultrasonically disrupted at room temperature for 20 min to obtain the assembled framework Tb-HOFs (40 mg). 2 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) was added to activate the carboxyl group. 50 μL of 5-hexen-1-ol was added and dissolved in a mixture of 3 mL of deionized water and 10 mL of anhydrous ethanol. The reaction was stirred at room temperature for 12 h.

[0079] S5. The reaction solution was centrifuged and washed three times with anhydrous ethanol and acetone respectively, and then dried in a vacuum drying oven to obtain a Tb-HOFs-olefin framework material.

[0080] S6. Take 30 mg of methyl spiropyran and dissolve it in toluene solution to prepare a solution with a concentration of 0.2 mol / L. Use a dropper to evenly add the solution to 100 mg of Tb-HOFs-olefin framework material. Let it stand at room temperature for 3 hours and dry naturally to obtain Tb-HOFs-olefin@SP photochromic material.

[0081] Figure 5 This is the ultraviolet absorption spectrum of the Tb-HOFs-olefin@SP photochromic material prepared in Example 3 after being irradiated with 365nm ultraviolet light for different times, and the color change diagram of the solid powder after being irradiated with 365nm ultraviolet light for different times.

[0082] Figure 6 This is the fluorescence emission spectrum of the Tb-HOFs-olefin@SP photochromic material prepared in Example 3 under 365nm ultraviolet light irradiation for different times and the solid fluorescence color change diagram after 365nm ultraviolet light irradiation for different times.

[0083] Figure 11 This is the infrared spectrum of the Tb-HOFs-olefin framework material prepared in Example 3 that was successfully modified with olefin alcohol.

[0084] Comparative Example 1

[0085] Preparation of HOFs@SP photochromic materials:

[0086] S1. Dissolve 1 g of 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TATB) in 100 mL of N,N-dimethylformamide (DMF). Add 300 mL of deionized water to the solution. Stir at 1000 rpm for 12 h at room temperature, and collect the white solid by centrifugation.

[0087] S2. The collected white solid was washed three times with acetone by centrifugation, then immersed in a dichloromethane solution (CH2Cl2) for three days, and finally dried by centrifugation in a vacuum to obtain the HOFs framework material.

[0088] S3. Take 30 mg of methyl spiropyran and dissolve it in toluene solution to prepare a solution with a concentration of 0.2 mol / L. Use a dropper to evenly add the solution to 100 mg of HOFs framework material. Let it stand at room temperature for 3 hours and dry naturally to obtain HOFs@SP photochromic material.

[0089] Figure 7 This is the ultraviolet absorption spectrum of the HOFs@SP photochromic material prepared in Comparative Example 1 after irradiation with 365nm ultraviolet light for different times and the color change diagram of the solid powder after irradiation with 365nm ultraviolet light for different times.

[0090] Figure 8 This is the fluorescence emission spectrum of the HOFs@SP photochromic material prepared in Comparative Example 1 under 365nm ultraviolet light irradiation for different times and the solid fluorescence color change diagram after 365nm ultraviolet light irradiation for different times.

[0091] Depend on Figure 1 、 Figure 3 and Figure 5 It can be seen that the photochromic material prepared by the present invention is very sensitive to ultraviolet light, can respond quickly within 30 seconds, and undergoes a physical color change. The color change is obvious and the contrast is high, which significantly improves the photochromic performance of spiropyran in the solid state.

[0092] Depend on Figure 4 and Figure 8 It can be seen that the fluorescence emission peak of the present invention first rises and then falls under ultraviolet light irradiation, which is due to the fluorescence quenching phenomenon caused by the close accumulation of spiropyran molecules after ring opening.

[0093] Depend on Figure 2 and Figure 6 It can be seen that Tb at 450nm 3+ As the ultraviolet light irradiation time increases, the fluorescence emission peak intensity gradually decreases, and energy resonance transfer occurs between the spiropyran and the material, realizing the dual fluorescence response of the material.

[0094] Depend on Figure 7 and Figure 8 It can be seen that when the HOFs framework material is not modified, the photochromic performance of the loaded spiropyran is poor, the contrast between the actual color and the fluorescent color before and after ultraviolet light irradiation is poor, and the color change response speed is slow, which greatly limits its application in information storage encryption and anti-counterfeiting fields.

[0095] Depend on Figure 9 It can be seen that the fluorescence color of the HOFs framework material modified by lanthanide metals is Tb 3+ The green fluorescence of HOFs proves that the HOFs framework material has been successfully modified by lanthanide elements.

[0096] Depend on Figure 10 It can be seen that characteristic peaks of double bonds and ester groups appear in the infrared spectrum of the HOFs framework material modified with olefin alcohol, indicating that the HOFs framework material has been successfully modified with olefin alcohol.

[0097] Depend on Figure 11 It can be seen that characteristic peaks of double bonds and ester groups appear in the infrared spectrum of the Tb-HOFs framework material modified with olefin alcohol, indicating that the Tb-HOFs framework material has been successfully modified with olefin alcohol.

[0098] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for improving the light response rate of a photochromic material, characterized in that the steps include: The stimuli-responsive color-changing material is prepared into a solution, and the modified HOFs framework material and the stimuli-responsive color-changing material solution are evenly mixed, and then allowed to stand and dried to obtain the photochromic material; The stimulus-responsive color-changing material is spiropyran; The HOFs framework material is assembled by ligand 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine; The modified HOFs framework material includes a lanthanide and / or double bond modified HOFs framework material; When the modified HOFs framework material is a lanthanide-modified HOFs framework material, the preparation steps include: preparing a Tb-HOFs framework material by complexing a lanthanum salt with the HOFs framework material; When the modified HOFs framework material is a double-bond modified HOFs framework material, the preparation steps include: modifying the HOFs framework material through olefin alcohol using an esterification reaction to obtain a HOFs-olefin framework material; When the modified HOFs framework material is a HOFs framework material modified with a lanthanide element and a double bond, the preparation steps include: first preparing a Tb-HOFs framework material by complexing a lanthanum salt with the HOFs framework material, and then modifying the Tb-HOFs framework material with olefin alcohol by an esterification reaction to obtain a Tb-HOFs-olefin framework material; The lanthanum salt is Tb(NO3)3·6H2O; and the olefin alcohol is 5-hexen-1-ol.

2. The method according to claim 1, characterized in that The mass ratio of the stimulus-responsive color-changing material to the modified HOFs framework material is 2-4:7-13.

3. The method according to claim 1, characterized in that The concentration of the solution is 0.2 mol / L.

4. Use of the photochromic material prepared by the method according to any one of claims 1 to 3 in the field of information storage and encryption.

5. Use of the photochromic material prepared by the method according to any one of claims 1 to 3 in the field of anti-counterfeiting.

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