Photochromic rare earth spiral body as well as preparation method and application thereof
By developing photochromic rare earth spirochete materials, using their color discoloration characteristics under ultraviolet light to form dynamic anti-counterfeiting QR codes, the existing anti-counterfeiting technology is easily deciphered, with long production cycles and high costs, and high efficiency and low cost are achieved dynamic anti-counterfeiting effect.
Patent Information
- Application Number
- CN202411361304.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-09-19
- Filing Date
- 2024-09-27
- Publication Date
- 2025-01-03
AI Technical Summary
The existing anti-counterfeiting technology is easy to be deciphered, has a long production cycle and is high in cost, making it difficult to effectively prevent the spread of counterfeit and shoddy goods.
A photochromic rare earth spirochete material is developed, and a photochromic rare earth spirochete is prepared through a specific synthetic method, and its discoloration characteristics under ultraviolet light are used to form a dynamic anti-counterfeiting QR code to achieve dynamic protection of information.
It improves the molecular motility of color-changing materials in solid state and enhances the photochemical reaction efficiency. The materials have high fatigue resistance and rapid response capabilities during repeated photochromic processes, which are low-cost and suitable for large-scale industrial applications.
Smart Images
Figure CN119242291A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of photochromic rare earth complex materials, and in particular relates to a photochromic rare earth helix and a preparation method and application thereof. Background Art
[0002] Against the backdrop of globalization and the rapid development of e-commerce, the speed of commodity circulation has accelerated, and the spread of counterfeit and shoddy goods has become more covert and rapid. Therefore, the importance of anti-counterfeiting technology has become increasingly prominent. It is not only a technical means, but also a manifestation of social responsibility and legal obligations. With the advancement and innovation of science and technology, such as the integration of new technologies such as blockchain and big data, anti-counterfeiting technology is becoming more intelligent and efficient, providing a more solid barrier to protect consumers, enterprises and markets. In short, the role of anti-counterfeiting technology in modern society is indispensable, and its importance and scope of application are constantly expanding, which has a far-reaching impact on building an honest society and sustainable development. Therefore, it is of great significance to the anti-counterfeiting market to be able to develop a material with superior performance for anti-counterfeiting.
[0003] At present, the existing anti-counterfeiting technologies mainly include digital anti-counterfeiting, physical anti-counterfeiting, chemical anti-counterfeiting and other means. Among them, ink anti-counterfeiting technology, laser anti-counterfeiting technology and texture anti-counterfeiting technology are the three most commonly used anti-counterfeiting technologies. However, each technology has its inherent limitations. Ink anti-counterfeiting technology is easy to be deciphered and used by counterfeiters; laser anti-counterfeiting technology has a long production cycle and high cost per sheet; texture anti-counterfeiting technology is expensive and has a narrow application range. In order to cope with the ever-evolving counterfeit and shoddy technology, the anti-counterfeiting industry needs to continue to innovate to maintain market order and protect the legitimate rights and interests of merchants and consumers. Summary of the invention
[0004] In order to solve the problems of the existing anti-counterfeiting technology being easy to be deciphered, having a long production cycle and high cost, the present invention provides a photochromic rare earth spiral and a preparation method and application thereof.
[0005] The structural formula of the photochromic rare earth spiromorph of the present invention is:
[0006]
[0007] The general structural formula of the photochromic rare earth helicoid is (HNEt 3 ) 2 [E 2 L 4 ], consisting of a ligand L and a rare earth element, wherein the structural formula of the ligand L is:
[0008]
[0009] The preparation method of the photochromic rare earth spiromorph of the present invention is carried out according to the following steps:
[0010] Step 1. Synthesis of 2-methylbenzofuran
[0011] 5.0-6.0 g of benzofuran was dissolved in 100-150 mL of anhydrous tetrahydrofuran. The reaction solution was cooled to -78°C under nitrogen protection. 37-39 mL of n-butyl lithium was added dropwise to the reaction solution, stirred at -78°C for 30 minutes, and then the reaction solution was restored to room temperature. 3-4 mL of iodomethane was added dropwise to the reaction solution. After the addition was completed, stirring was continued at room temperature for 5 hours. After the reaction was complete, water was added to quench the reaction. The quenched reaction solution was extracted with 90-150 mL of ethyl acetate, the organic layers were combined and washed with anhydrous Na 2 SO 4 Dry and then filter to remove Na 2 SO 4 ; The solution was concentrated under reduced pressure to obtain a crude product, and the crude product was purified by column chromatography to obtain 2-methylbenzofuran; it was white needle-shaped crystals with a yield of 90% to 92%;
[0012] Step 2: Synthesis of 3-bromo-2-methylbenzofuran
[0013] Dissolve 5.0-7.0 g of 2-methylbenzofuran in 100-130 mL of CHCl at 0 °C. 3 2-3 mL of liquid bromine was added dropwise to the reaction solution. After the addition of liquid bromine was completed, the reaction solution was returned to room temperature and stirred for 10 hours. After the reaction was complete, the obtained mixture was washed several times with a saturated sodium thiosulfate aqueous solution until the organic layer no longer changed color. The organic layers were combined and washed with anhydrous Na 2 SO 4 The organic layer was dried and concentrated under reduced pressure to obtain a crude product, which was purified by column chromatography to obtain 3-bromo-2-methylbenzofuran as white crystals with a yield of 92% to 93%.
[0014] Step 3: Synthesis of 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene
[0015] Under nitrogen protection, 5.00-7.00 g of 3-bromo-2-methylbenzofuran was dissolved in 100-150 mL of anhydrous tetrahydrofuran, and then the reaction solution was cooled to -78 ° C, 17-19 mL of n-butyl lithium was added dropwise to the reaction solution, and after the addition was complete, the mixed solution was stirred at -78 ° C for 1 hour, 1.5-2.0 mL of octafluorocyclopentene anhydrous tetrahydrofuran solution was added dropwise to the mixed solution at a rate of 1 s / drop, and after the mixed solution was stirred for 30 minutes, the mixed solution was returned to room temperature and stirred for 8 hours. After the reaction was complete, 10-12 mL of methanol was added to the mixed solution to quench the reaction, the reaction solution was poured into water and extracted with 150-180 mL of ethyl acetate, the organic layer solution was combined and washed with anhydrous Na 2SO 4 Dry, remove Na by vacuum filtration 2 SO 4 The organic layer solution was distilled under reduced pressure to obtain a black oily crude product, which was purified by column chromatography to obtain 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene; it was white crystals with a yield of 41% to 45%;
[0016] Step 4: Synthesis of 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene
[0017] Dissolve 1.0-1.5g of 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene in 20-25mL of nitrobenzene, then add 0.5-1.0g of acetyl chloride to the solution, stir at room temperature for 30 minutes after the solution becomes turbid, then put the solution into ice water and cool to 0°C, add 1.5-2.0g of anhydrous aluminum chloride to the solution, stir for 12 hours after returning to room temperature, and after the reaction is complete, add 5-10mL of 2mol / L dilute hydrochloric acid to the reaction solution to quench the reaction; pour the resulting mixture into 60-70mL of water and extract with 90-150mL of ethyl acetate, retain the organic layer solution and purify with anhydrous Na 2 SO 4 Dry, and remove Na by vacuum filtration. 2 SO 4 , the organic layer solution was distilled under reduced pressure to obtain a black oily crude product, the crude product was purified by column chromatography to obtain a yellow oily substance, and then recrystallized from a mixed solution of ethyl acetate and n-hexane to obtain 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene; it was a white powder with a yield of 45% to 55%;
[0018] The volume ratio of ethyl acetate to n-hexane in the ethyl acetate and n-hexane mixture is 3:1
[0019] Step 5: Synthesis of ligand L:
[0020] Add 5-7 mL of ethyl trifluoroacetate to 20-30 mL of anhydrous ethylene glycol dimethyl ether solution containing 0.4-0.5 g of sodium methoxide, stir for 5-10 minutes, add 1.0-1.5 g of 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene after the solution is clarified, and stir at room temperature for 24 hours; after the reaction is complete, pour the resulting mixture into 60-70 mL of ice water and adjust the pH value to 2-3 with 1.0 mol / L dilute hydrochloric acid, filter to obtain a brown solid, dry it, and then recrystallize it with a mixed solvent of ethyl acetate and hexane to obtain ligand L; it is light yellow crystals with a yield of 60%-70%;
[0021] The volume ratio of ethyl acetate to hexane in the mixed solvent of ethyl acetate and hexane is 3:1;
[0022] Step 6: (HNEt 3 ) 2 [E 2 L 4 Synthesis of
[0023] Dissolve 0.2-0.3 g of ligand L and 0.06-0.07 g of triethylamine in 8-10 mL of methanol to obtain a reaction solution. 3 6H 2 O is dissolved in 10-12 mL of methanol to obtain a rare earth salt solution; the rare earth salt solution is added to the reaction solution, and the reaction solution is stirred for 24-30 hours after it is completely clarified, and then the reaction solution is added to 10-20 mL of water to form a flocculent precipitate. After standing for a period of time, the precipitate is filtered off under reduced pressure to retain the precipitate, and the precipitate is dissolved in acetone and transferred to n-hexane until a precipitate is precipitated, the precipitate is collected, and then the precipitate is vacuum dried to obtain (HNEt 3 ) 2 [E 2 L 4 ]; the yield is 70% to 80%.
[0024] The developing solvent during column chromatography purification in steps 1, 2 and 3 is petroleum ether;
[0025] The developing solvents for column chromatography purification in steps 1, 2 and 3 are petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate is 3:1;
[0026] The method for preparing an anti-counterfeiting two-dimensional code with photochromic properties by using a photochromic rare earth spirosome of the present invention is carried out according to the following steps:
[0027] 1. dissolving the synthesized photochromic rare earth spirosome in a tetrahydrofuran solution to obtain a photochromic rare earth spirosome solution;
[0028] 2. forming a two-dimensional code pattern on a substrate;
[0029] 3. Covering the photochromic rare earth spirosome solution obtained in step 1 on the two-dimensional code pattern; curing after irradiation with ultraviolet light of 350 to 370 nm for 5 to 10 minutes to obtain an anti-counterfeiting two-dimensional code with photochromic properties;
[0030] 4. In the absence of ultraviolet light, the anti-counterfeiting QR code with photochromic properties is colorless, the information in the QR code pattern is fully displayed, and the information can be successfully read; under ultraviolet light, the photochromic rare earth spiral changes color and covers the covered part of the QR code pattern, resulting in an incomplete QR code and inability to read the information, forming a dynamic anti-counterfeiting effect.
[0031] Compared with the prior art, the present invention has the following advantages:
[0032] 1. The rare earth helicoid of the present invention is a supramolecular helicoid constructed by four ligands and metal ions. The larger ionic radius of the rare earth makes the supramolecular (HNEt 3 ) 2 [E 2 L 4 ] has a certain hole structure, which allows the photochromic unit to rotate under light, thus effectively solving the problem of spatial limitation of molecular motion in the solid state of the color-changing material, thereby improving its color-changing performance in the film-forming material.
[0033] 2. In the parallel conformation, the interaction of ligand molecules may lead to unfavorable energy states or steric hindrances, limiting the occurrence of photochemical reactions. In the antiparallel conformation, the spatial arrangement between molecules is more conducive to interaction and energy transfer, making the conformation more stable, thereby improving the efficiency of photochemical reactions. The formation of the supramolecular structure of the rare earth helicoid of the present invention makes the rare earth helicoid structure orderly, the interaction between ligand molecules is optimized, and the ineffective consumption of energy is reduced, thereby more effectively realizing the antiparallel conformation conversion, solving the problem that the parallel conformation of the ligand cannot be completely converted into the antiparallel conformation.
[0034] 3. The flexibility and variability of the helical structure of the photochromic rare earth spirosome of the present invention enables this conformational change to respond quickly to light stimulation, so that the photochromic rare earth spirosome material changes color quickly, and the color development rate is <3s in a strong light environment.
[0035] 4. Since the photochromic rare earth spirosome material of the present invention is composed of rare earth elements and organic ligands, the rare earth elements and the coordination units provide a strong coordination effect in the material, enhance the stability of the entire molecule, reduce the possibility of structural fatigue, and ensure the high reversibility of energy transfer and structural changes in the photochromic process while maintaining the integrity and stability of the structure during repeated photochromic processes. Therefore, the photochromic rare earth spirosome material of the present invention has strong fatigue resistance, and the absorbance decreases by <0.5% after 10,000 switching cycles; it can be reused.
[0036] 5. The synthesis method of the photochromic rare earth supramolecular helicoid of the present invention is relatively simple and has low synthesis cost, and has the possibility of large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Figure 1 This is a picture of a photochromic QR code under natural light;
[0038] Figure 2 This is a picture of a photochromic QR code under ultraviolet light. DETAILED DESCRIPTION
[0039] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any reasonable combination of the specific implementation modes.
[0040] Specific implementation method 1: The structural formula of the photochromic rare earth spiral in this implementation method is:
[0041]
[0042] The general structural formula of the photochromic rare earth helicoid is (HNEt 3 ) 2 [E 2 L 4 ], consisting of a ligand L and a rare earth element, wherein the structural formula of the ligand L is:
[0043]
[0044] This embodiment has the following beneficial effects:
[0045] 1. The rare earth helicoid of this embodiment is a supramolecular helicoid constructed by four ligands and metal ions. The large ionic radius of the rare earth makes the supramolecular (HNEt 3 ) 2 [E 2 L 4 ] has a certain hole structure, which allows the photochromic unit to rotate under light, thus effectively solving the problem of spatial limitation of molecular motion in the solid state of the color-changing material, thereby improving its color-changing performance in the film-forming material.
[0046] 2. In the parallel conformation, the interaction of ligand molecules may lead to unfavorable energy states or steric hindrances, limiting the occurrence of photochemical reactions. In the antiparallel conformation, the spatial arrangement between molecules is more conducive to interaction and energy transfer, making the conformation more stable, thereby improving the efficiency of photochemical reactions. The formation of the supramolecular structure of the rare earth helicoid of this embodiment makes the rare earth helicoid structure orderly, the interaction between ligand molecules is optimized, and the ineffective consumption of energy is reduced, thereby more effectively realizing the antiparallel conformation conversion, solving the problem that the parallel conformation of the ligand cannot be completely converted into the antiparallel conformation.
[0047] 3. The flexibility and variability of the helical structure of the photochromic rare earth spirosome in this embodiment enables the conformational change to respond quickly to light stimulation, so that the photochromic rare earth spirosome material changes color quickly, with a color development rate of <3s in a strong light environment.
[0048] 4. Since the photochromic rare earth spirosome material of this embodiment is composed of rare earth elements and organic ligands, the rare earth elements and the coordination units provide a strong coordination effect in the material, enhance the stability of the entire molecule, reduce the possibility of structural fatigue, and ensure the high reversibility of energy transfer and structural changes in the photochromic process while maintaining the integrity and stability of the structure during repeated photochromic processes. Therefore, the photochromic rare earth spirosome material of this embodiment has strong fatigue resistance, and the absorbance decreases by <0.5% after 10,000 switching cycles; it can be reused.
[0049] 5. The synthesis method of the photochromic rare earth supramolecular helicoid of this embodiment is relatively simple and has low synthesis cost, and has the possibility of large-scale industrial application.
[0050] Specific implementation method 2: The preparation method of the photochromic rare earth spiral in this implementation method is carried out according to the following steps:
[0051] Step 1. Synthesis of 2-methylbenzofuran
[0052] 5.0-6.0 g of benzofuran was dissolved in 100-150 mL of anhydrous tetrahydrofuran. The reaction solution was cooled to -78°C under nitrogen protection. 37-39 mL of n-butyl lithium was added dropwise to the reaction solution, stirred at -78°C for 30 minutes, and then the reaction solution was restored to room temperature. 3-4 mL of iodomethane was added dropwise to the reaction solution. After the addition was completed, stirring was continued at room temperature for 5 hours. After the reaction was complete, water was added to quench the reaction. The quenched reaction solution was extracted with 90-150 mL of ethyl acetate, the organic layers were combined and washed with anhydrous Na 2 SO 4 Dry and then filter to remove Na 2 SO 4 ; The solution was concentrated under reduced pressure to obtain a crude product, and the crude product was purified by column chromatography to obtain 2-methylbenzofuran; it was white needle-shaped crystals with a yield of 90% to 92%;
[0053] Step 2: Synthesis of 3-bromo-2-methylbenzofuran
[0054] Dissolve 5.0-7.0 g of 2-methylbenzofuran in 100-130 mL of CHCl at 0 °C. 3 2-3 mL of liquid bromine was added dropwise to the reaction solution. After the addition of liquid bromine was completed, the reaction solution was returned to room temperature and stirred for 10 hours. After the reaction was complete, the obtained mixture was washed several times with a saturated sodium thiosulfate aqueous solution until the organic layer no longer changed color. The organic layers were combined and washed with anhydrous Na 2 SO 4The organic layer was dried and concentrated under reduced pressure to obtain a crude product, which was purified by column chromatography to obtain 3-bromo-2-methylbenzofuran as white crystals with a yield of 92% to 93%.
[0055] Step 3: Synthesis of 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene
[0056] Under nitrogen protection, 5.00-7.00 g of 3-bromo-2-methylbenzofuran was dissolved in 100-150 mL of anhydrous tetrahydrofuran, and then the reaction solution was cooled to -78 ° C, 17-19 mL of n-butyl lithium was added dropwise to the reaction solution, and after the addition was complete, the mixed solution was stirred at -78 ° C for 1 hour, 1.5-2.0 mL of octafluorocyclopentene anhydrous tetrahydrofuran solution was added dropwise to the mixed solution at a rate of 1 s / drop, and after the mixed solution was stirred for 30 minutes, the mixed solution was returned to room temperature and stirred for 8 hours. After the reaction was complete, 10-12 mL of methanol was added to the mixed solution to quench the reaction, the reaction solution was poured into water and extracted with 150-180 mL of ethyl acetate, the organic layer solution was combined and washed with anhydrous Na 2 SO 4 Dry, and remove Na by vacuum filtration. 2 SO 4 The organic layer solution was distilled under reduced pressure to obtain a black oily crude product, which was purified by column chromatography to obtain 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene; it was white crystals with a yield of 41% to 45%;
[0057] Step 4: Synthesis of 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene
[0058] Dissolve 1.0-1.5g of 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene in 20-25mL of nitrobenzene, then add 0.5-1.0g of acetyl chloride to the solution, stir at room temperature for 30 minutes after the solution becomes turbid, then put the solution into ice water and cool to 0°C, add 1.5-2.0g of anhydrous aluminum chloride to the solution, stir for 12 hours after returning to room temperature, and after the reaction is complete, add 5-10mL of dilute hydrochloric acid to the reaction solution to quench the reaction; pour the resulting mixture into 60-70mL of water and extract with 90-150mL of ethyl acetate, retain the organic layer solution and purify it with anhydrous Na 2 SO 4 Dry, and remove Na by vacuum filtration. 2 SO 4, the organic layer solution was distilled under reduced pressure to obtain a black oily crude product, the crude product was purified by column chromatography to obtain a yellow oily substance, and then recrystallized from a mixed solution of ethyl acetate and n-hexane to obtain 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene; it was a white powder with a yield of 45% to 55%;
[0059] Step 5: Synthesis of ligand L:
[0060] Add 5-7 mL of ethyl trifluoroacetate to 20-30 mL of anhydrous ethylene glycol dimethyl ether solution containing 0.4-0.5 g of sodium methoxide, stir, and after the solution is clarified, add 1.0-1.5 g of 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene, and stir at room temperature for 24 hours; after the reaction is complete, pour the resulting mixture into 60-70 mL of ice water and adjust the pH value to 2-3 with dilute hydrochloric acid, filter to obtain a brown solid, dry it, and then recrystallize it with a mixed solvent of ethyl acetate and hexane to obtain ligand L; it is light yellow crystals with a yield of 60%-70%;
[0061] Step 6: (HNEt 3 ) 2 [E 2 L 4 Synthesis of
[0062] Dissolve 0.2-0.3 g of ligand L and 0.06-0.07 g of triethylamine in 8-10 mL of methanol to obtain a reaction solution. 3 6H 2 O is dissolved in 10-12 mL of methanol to obtain a rare earth salt solution; the rare earth salt solution is added to the reaction solution, and the reaction solution is stirred for 24-30 hours after it is completely clarified, and then the reaction solution is added to 10-20 mL of water to form a flocculent precipitate. After standing for a period of time, the precipitate is filtered off under reduced pressure to retain the precipitate, and the precipitate is dissolved in acetone and transferred to n-hexane until a precipitate is precipitated, the precipitate is collected, and then the precipitate is vacuum dried to obtain (HNEt 3 ) 2 [E 2 L 4 ]; the yield is 70% to 80%.
[0063] 1. The rare earth helicoid of this embodiment is a supramolecular helicoid constructed by four ligands and metal ions. The large ionic radius of the rare earth makes the supramolecular (HNEt 3 ) 2 [E 2 L 4] has a certain hole structure, which allows the photochromic unit to rotate under light, thus effectively solving the problem of spatial limitation of molecular motion in the solid state of the color-changing material, thereby improving its color-changing performance in the film-forming material.
[0064] 2. In the parallel conformation, the interaction of ligand molecules may lead to unfavorable energy states or steric hindrances, limiting the occurrence of photochemical reactions. In the antiparallel conformation, the spatial arrangement between molecules is more conducive to interaction and energy transfer, making the conformation more stable, thereby improving the efficiency of photochemical reactions. The formation of the supramolecular structure of the rare earth helicoid of this embodiment makes the rare earth helicoid structure orderly, the interaction between ligand molecules is optimized, and the ineffective consumption of energy is reduced, thereby more effectively realizing the antiparallel conformation conversion, solving the problem that the parallel conformation of the ligand cannot be completely converted into the antiparallel conformation.
[0065] 3. The flexibility and variability of the helical structure of the photochromic rare earth spirosome in this embodiment enables the conformational change to respond quickly to light stimulation, so that the photochromic rare earth spirosome material changes color quickly, with a color development rate of <3s in a strong light environment.
[0066] 4. Since the photochromic rare earth spirosome material of this embodiment is composed of rare earth elements and organic ligands, the rare earth elements and the coordination units provide a strong coordination effect in the material, enhance the stability of the entire molecule, reduce the possibility of structural fatigue, and ensure the high reversibility of energy transfer and structural changes in the photochromic process while maintaining the integrity and stability of the structure during repeated photochromic processes. Therefore, the photochromic rare earth spirosome material of this embodiment has strong fatigue resistance, and the absorbance decreases by <0.5% after 10,000 switching cycles; it can be reused.
[0067] 5. The synthesis method of the photochromic rare earth supramolecular helicoid of this embodiment is relatively simple and has low synthesis cost, and has the possibility of large-scale industrial application.
[0068] Specific implementation method three: This implementation method is different from specific implementation method two in that: the volume ratio of ethyl acetate to n-hexane in the ethyl acetate and n-hexane mixed solution described in step four is 3:1.
[0069] Specific implementation method 4: This implementation method is different from specific implementation method 2 in that the concentration of the dilute hydrochloric acid in step 4 is 2 mol / L.
[0070] Specific implementation mode 5: This implementation mode is different from specific implementation mode 2 in that: the volume ratio of ethyl acetate to hexane in the mixed solvent of ethyl acetate and hexane in step 5 is 3:1.
[0071] Specific implementation method 6: This implementation method is different from specific implementation method 2 in that: the concentration of the dilute hydrochloric acid in step 5 is 1 mol / L.
[0072] Specific implementation method 7: This implementation method is different from specific implementation method 2 in that: the stirring time in step 5 is 5 to 10 minutes.
[0073] Specific embodiment eight: This embodiment differs from specific embodiment two in that the developing solvent used in the column chromatography purification in steps one, two and three is petroleum ether.
[0074] Specific embodiment 9: This embodiment is different from specific embodiment 2 in that the developing solvents used in the column chromatography purification in steps 1, 2 and 3 are petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate is 3:1.
[0075] Specific embodiment 10: The method for preparing an anti-counterfeiting two-dimensional code with photochromic properties using a photochromic rare earth spiral in this embodiment is carried out according to the following steps:
[0076] 1. dissolving the synthesized photochromic rare earth spirosome in a tetrahydrofuran solution to obtain a photochromic rare earth spirosome solution;
[0077] 2. forming a two-dimensional code pattern on a substrate;
[0078] 3. Covering the photochromic rare earth spirosome solution obtained in step 1 on the two-dimensional code pattern; curing after irradiation with ultraviolet light of 350 to 370 nm for 5 to 10 minutes to obtain an anti-counterfeiting two-dimensional code with photochromic properties;
[0079] 4. In the absence of ultraviolet light, the anti-counterfeiting QR code with photochromic properties is colorless, the information in the QR code pattern is fully displayed, and the information can be successfully read; under ultraviolet light, the photochromic rare earth spiral changes color and covers the covered part of the QR code pattern, resulting in an incomplete QR code and inability to read the information, forming a dynamic anti-counterfeiting effect.
[0080] 1. The rare earth helicoid of this embodiment is a supramolecular helicoid constructed by four ligands and metal ions. The large ionic radius of the rare earth makes the supramolecular (HNEt 3 ) 2 [E 2 L 4 ] has a certain hole structure, which allows the photochromic unit to rotate under light, thus effectively solving the problem of spatial limitation of molecular motion in the solid state of the color-changing material, thereby improving its color-changing performance in the film-forming material.
[0081] 2. In the parallel conformation, the interaction of ligand molecules may lead to unfavorable energy states or steric hindrances, limiting the occurrence of photochemical reactions. In the antiparallel conformation, the spatial arrangement between molecules is more conducive to interaction and energy transfer, making the conformation more stable, thereby improving the efficiency of photochemical reactions. The formation of the supramolecular structure of the rare earth helicoid of this embodiment makes the rare earth helicoid structure orderly, the interaction between ligand molecules is optimized, and the ineffective consumption of energy is reduced, thereby more effectively realizing the antiparallel conformation conversion, solving the problem that the parallel conformation of the ligand cannot be completely converted into the antiparallel conformation.
[0082] 3. The flexibility and variability of the helical structure of the photochromic rare earth spirosome in this embodiment enables the conformational change to respond quickly to light stimulation, so that the photochromic rare earth spirosome material changes color quickly, with a color development rate of <3s in a strong light environment.
[0083] 4. Since the photochromic rare earth spirosome material of this embodiment is composed of rare earth elements and organic ligands, the rare earth elements and the coordination units provide a strong coordination effect in the material, enhance the stability of the entire molecule, reduce the possibility of structural fatigue, and ensure the high reversibility of energy transfer and structural changes in the photochromic process while maintaining the integrity and stability of the structure during repeated photochromic processes. Therefore, the photochromic rare earth spirosome material of this embodiment has strong fatigue resistance, and the absorbance decreases by <0.5% after 10,000 switching cycles; it can be reused.
[0084] 5. The synthesis method of the photochromic rare earth supramolecular helicoid of this embodiment is relatively simple and has low synthesis cost, and has the possibility of large-scale industrial application.
[0085] Embodiment 1:
[0086] The structural formula of the photochromic rare earth spiromorph in this embodiment is:
[0087]
[0088] The general structural formula of the photochromic rare earth helicoid is (HNEt 3 ) 2 [E 2 L 4 ], consisting of a ligand L and a rare earth element, wherein the structural formula of the ligand L is:
[0089]
[0090] The preparation method of the photochromic rare earth spiromorph in this embodiment is carried out according to the following steps:
[0091] Step 1. Synthesis of 2-methylbenzofuran
[0092] 5.7 g of benzofuran was dissolved in 100 mL of anhydrous tetrahydrofuran. The reaction solution was cooled to -78 °C under nitrogen protection. 38 mL of n-butyl lithium was added dropwise to the reaction solution, stirred at -78 °C for 30 minutes, and then the reaction solution was restored to room temperature. 3.5 mL of iodomethane was added dropwise to the reaction solution. After the addition was completed, stirring was continued at room temperature for 5 hours. After the reaction was complete, water was added to quench the reaction. The quenched reaction solution was extracted with 90 mL of ethyl acetate, the organic layers were combined and washed with anhydrous Na 2 SO 4 Dry and then filter to remove Na 2 SO 4 ; The solution was concentrated under reduced pressure to obtain a crude product, which was purified by column chromatography to obtain 2-methylbenzofuran; it was white needle-shaped crystals with a yield of 90.48%;
[0093] Step 2: Synthesis of 3-bromo-2-methylbenzofuran
[0094] Dissolve 5.0 g of 2-methylbenzofuran in 100 mL of CHCl at 0 °C. 3 2 mL of liquid bromine was added dropwise to the reaction solution. After the addition of liquid bromine was completed, the reaction solution was returned to room temperature and stirred for 10 hours. After the reaction was complete, the obtained mixture was washed several times with a saturated sodium thiosulfate aqueous solution until the organic layer no longer changed color. The organic layers were combined and washed with anhydrous Na 2 SO 4 The organic layer was dried and concentrated under reduced pressure to obtain a crude product, which was purified by column chromatography to obtain 3-bromo-2-methylbenzofuran as white crystals with a yield of 92.69%.
[0095] Step 3: Synthesis of 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene
[0096] Under nitrogen protection, 5.00 g of 3-bromo-2-methylbenzofuran was dissolved in 100 mL of anhydrous tetrahydrofuran, and then the reaction solution was cooled to -78 ° C, 17 mL of n-butyl lithium was added dropwise to the reaction solution, and after the addition was completed, the mixed solution was stirred at -78 ° C for 1 hour, 1.5 mL of octafluorocyclopentene anhydrous tetrahydrofuran solution was added dropwise to the mixed solution at a rate of 1 s / drop, and after the mixed solution was stirred for 30 minutes, the mixed solution was returned to room temperature and stirred for 8 hours. After the reaction was complete, 10 mL of methanol was added to the mixed solution to quench the reaction, the reaction solution was poured into water and extracted with 150 mL of ethyl acetate, the organic layer solution was combined and washed with anhydrous Na 2 SO 4 Dry, and remove Na by vacuum filtration. 2 SO 4The organic layer solution was distilled under reduced pressure to obtain a black oily crude product, which was purified by column chromatography to obtain 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene; it was white crystals with a yield of 41%;
[0097] Step 4: Synthesis of 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene
[0098] 1.0 g of 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene was dissolved in 20 mL of nitrobenzene, and then 0.5 g of acetyl chloride was added to the solution. After the solution became turbid, it was stirred at room temperature for 30 minutes, and then the solution was placed in ice water and cooled to 0°C. 1.5 g of anhydrous aluminum chloride was added to the solution, and it was stirred for 12 hours after returning to room temperature. After the reaction was complete, 10 mL of 2 mol / L dilute hydrochloric acid was added to the reaction solution to quench the reaction; the resulting mixture was poured into 60 mL of water and extracted with 90 mL of ethyl acetate, and the organic layer solution was retained and precipitated with anhydrous Na 2 SO 4 Dry, and remove Na by vacuum filtration. 2 SO 4 , the organic layer solution was distilled under reduced pressure to obtain a black oily crude product, the crude product was purified by column chromatography to obtain a yellow oily substance, and then recrystallized from a mixed solution of ethyl acetate and n-hexane to obtain 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene; it was a white powder with a yield of 45%;
[0099] The volume ratio of ethyl acetate to n-hexane in the ethyl acetate and n-hexane mixture is 3:1
[0100] Step 5: Synthesis of ligand L:
[0101] Add 5 mL of ethyl trifluoroacetate to a 20 mL anhydrous ethylene glycol dimethyl ether solution containing 0.4 g of sodium methoxide, stir for 5 minutes, add 1.0 g of 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene after the solution is clarified, and stir at room temperature for 24 hours; after the reaction is complete, pour the resulting mixture into 60 mL of ice water and adjust the pH value to 3 with 1.0 mol / L dilute hydrochloric acid, filter to obtain a brown solid, dry it, and then recrystallize it with a mixed solvent of ethyl acetate and hexane to obtain ligand L; it is light yellow crystals with a yield of 60%;
[0102] The volume ratio of ethyl acetate to hexane in the mixed solvent of ethyl acetate and hexane is 3:1;
[0103] Step 6: (HNEt 3 ) 2 [E 2 L 4 Synthesis of
[0104] 0.2 g of ligand L and 0.06 g of triethylamine were dissolved in 8 mL of methanol to obtain a reaction solution. EuCl 3 6H 2 O was dissolved in 10 mL of methanol to obtain a rare earth salt solution; the rare earth salt solution was added to the reaction solution, and the reaction solution was stirred for 24 hours after it was completely clarified, and then the reaction solution was added to 10 mL of water to form a flocculent precipitate. After standing for a period of time, the precipitate was filtered under reduced pressure to retain the precipitate, and the precipitate was dissolved in acetone and transferred to n-hexane until a precipitate was precipitated, the precipitate was collected, and then the precipitate was vacuum dried to obtain (HNEt 3 ) 2 [E 2 L 4 ]; the yield is 70%.
[0105] The developing solvent during column chromatography purification in steps 1, 2 and 3 is petroleum ether;
[0106] The developing solvents for column chromatography purification in steps 1, 2 and 3 are petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate is 3:1;
[0107] The method for preparing an anti-counterfeiting two-dimensional code with photochromic properties using the photochromic rare earth spirosome is carried out according to the following steps:
[0108] 1. dissolving the synthesized photochromic rare earth spirosome in a tetrahydrofuran solution to obtain a photochromic rare earth spirosome solution;
[0109] 2. forming a two-dimensional code pattern on a substrate;
[0110] 3. Covering the photochromic rare earth spirosome solution obtained in step 1 on the two-dimensional code pattern; curing after irradiation with ultraviolet light of 350 to 370 nm for 5 to 10 minutes to obtain an anti-counterfeiting two-dimensional code with photochromic properties;
[0111] Four, Figure 1 This is a picture of a photochromic QR code under natural light; Figure 2 This is a picture of a photochromic QR code under ultraviolet light. Without ultraviolet light, the anti-counterfeiting QR code with photochromic properties is colorless, the information in the QR code pattern is fully displayed, and the information can be successfully read; under ultraviolet light, the photochromic rare earth spiral changes color and covers the part of the QR code pattern, resulting in an incomplete QR code and an inability to read information, forming a dynamic anti-counterfeiting effect.
Claims
1. A photochromic rare earth spirochete, characterized in that: The structural formula of the photochromic rare earth spirochete is: The photochromic rare earth spirosome has a general structural formula of (HNEt3)2[Eu2L4], and is composed of a ligand L and a rare earth element. The structural formula of the ligand L is:
2. The method for preparing the photochromic rare earth spiral according to claim 1, characterized in that: The preparation method of the photochromic rare earth spirosome is carried out according to the following steps: Step 1. Synthesis of 2-methylbenzofuran 5.0-6.0 g of benzofuran was dissolved in 100-150 mL of anhydrous tetrahydrofuran, and the reaction solution was cooled to -78°C under nitrogen protection; 37-39 mL of n-butyl lithium was added dropwise to the reaction solution, and the mixture was stirred at -78°C for 30 minutes, and then the reaction solution was restored to room temperature; 3-4 mL of iodomethane was added dropwise to the reaction solution, and the mixture was stirred at room temperature for 5 hours after the addition was completed. After the reaction was complete, water was added to quench the reaction, and the quenched reaction solution was extracted with 90-150 mL of ethyl acetate, the organic layers were combined and dried with anhydrous Na2SO4, and then the Na2SO4 was removed by suction filtration; the solution was concentrated under reduced pressure to obtain a crude product, and the crude product was purified by column chromatography to obtain 2-methylbenzofuran, which was white needle-shaped crystals with a yield of 90%-92%; Step 2: Synthesis of 3-bromo-2-methylbenzofuran 5.0-7.0 g of 2-methylbenzofuran was dissolved in 100-130 mL of CHCl3 at 0°C, and 2-3 mL of liquid bromine was added dropwise to the reaction solution. After the addition of liquid bromine was completed, the reaction solution was returned to room temperature and stirred for 10 hours. After the reaction was complete, the obtained mixed solution was washed with a saturated sodium thiosulfate aqueous solution for several times until the organic layer no longer changed color; the organic layers were combined, dried with anhydrous Na2SO4, and concentrated under reduced pressure to obtain a crude product, which was purified by column chromatography to obtain 3-bromo-2-methylbenzofuran; it was white crystals with a yield of 92%-93%; Step 3: Synthesis of 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene Under nitrogen protection, 5.00-7.00 g of 3-bromo-2-methylbenzofuran was dissolved in 100-150 mL of anhydrous tetrahydrofuran, and then the reaction solution was cooled to -78 ° C, 17-19 mL of n-butyl lithium was added dropwise to the reaction solution, and after the addition was completed, the mixed solution was stirred at -78 ° C for 1 hour, 1.5-2.0 mL of octafluorocyclopentene anhydrous tetrahydrofuran solution was added dropwise to the mixed solution at a rate of 1 s / drop, and after the mixed solution was stirred for 30 minutes, the mixed solution was returned to room temperature and The mixture was stirred for 8 hours. After the reaction was complete, 10-12 mL of methanol was added to the mixture to quench the reaction. The reaction solution was poured into water and extracted with 150-180 mL of ethyl acetate. The organic layer solution was combined and dried over anhydrous Na2SO4. Na2SO4 was removed by vacuum filtration. The organic layer solution was distilled under reduced pressure to obtain a black oily crude product. The crude product was purified by column chromatography to obtain 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene; it was white crystals with a yield of 41% to 45%. Step 4: Synthesis of 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene Dissolve 1.0-1.5 g of 1,2-bis(2-methylbenzofuran-3-yl)hexafluorocyclopentene in 20-25 mL of nitrobenzene, then add 0.5-1.0 g of acetyl chloride to the solution, stir for 30 minutes at room temperature after the solution becomes turbid, then put the solution into ice water and cool to 0°C, add 1.5-2.0 g of anhydrous aluminum chloride to the solution, stir for 12 hours after returning to room temperature, and after the reaction is complete, add 5-10 mL of dilute hydrochloric acid to the reaction solution to quench the reaction; The product was poured into 60-70 mL of water and extracted with 90-150 mL of ethyl acetate, the organic layer solution was retained and dried with anhydrous Na2SO4, the Na2SO4 was removed by vacuum filtration, and the organic layer solution was distilled under reduced pressure to obtain a black oily crude product, which was purified by column chromatography to obtain a yellow oily product, which was then recrystallized with a mixed solution of ethyl acetate and n-hexane to obtain 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene; it was a white powder with a yield of 45% to 55%; Step 5: Synthesis of ligand L: Add 5-7 mL of ethyl trifluoroacetate to 20-30 mL of anhydrous ethylene glycol dimethyl ether solution containing 0.4-0.5 g of sodium methoxide, stir, and after the solution is clarified, add 1.0-1.5 g of 1,2-bis(6-acetyl-2-methylbenzofuran-3-yl)hexafluorocyclopentene, and stir at room temperature for 24 hours; after the reaction is complete, pour the resulting mixture into 60-70 mL of ice water and adjust the pH value to 2-3 with dilute hydrochloric acid, filter to obtain a brown solid, dry it, and then recrystallize it with a mixed solvent of ethyl acetate and hexane to obtain ligand L; it is light yellow crystals with a yield of 60%-70%; Step 6. Synthesis of (HNEt3)2[Eu2L4] Dissolve 0.2-0.3 g of ligand L and 0.06-0.07 g of triethylamine in 8-10 mL of methanol to obtain a reaction solution, dissolve EuCl3·6H2O in 10-12 mL of methanol at room temperature to obtain a rare earth salt solution; add the rare earth salt solution to the reaction solution, continue stirring for 24-30 hours after the reaction solution is completely clarified, then add the reaction solution to 10-20 mL of water to form a flocculent precipitate, let it stand for a period of time, filter under reduced pressure to retain the precipitate, dissolve the precipitate in acetone and transfer it to n-hexane until a precipitate is precipitated, collect the precipitate, and then vacuum dry the precipitate to obtain (HNEt3)2[Eu2L4]; the yield is 70%-80%.
3. The method for preparing the photochromic rare earth spiral according to claim 2, characterized in that: The volume ratio of ethyl acetate to n-hexane in the ethyl acetate and n-hexane mixture described in step 4 is 3:
1.
4. The method for preparing the photochromic rare earth helicoid according to claim 2, characterized in that: The concentration of the dilute hydrochloric acid in step 4 is 2 mol / L.
5. The method for preparing the photochromic rare earth spiral according to claim 2, characterized in that: The volume ratio of ethyl acetate to hexane in the mixed solvent of ethyl acetate and hexane in step 5 is 3:
1.
6. The method for preparing the photochromic rare earth spiral according to claim 2, characterized in that: The concentration of the dilute hydrochloric acid in step 5 is 1 mol / L.
7. The method for preparing the photochromic rare earth helicoid according to claim 2, characterized in that: The stirring time in step 5 is 5 to 10 minutes.
8. The method for preparing the photochromic rare earth spiral according to claim 2, characterized in that: The developing solvent used in the column chromatography purification in steps 1, 2 and 3 is petroleum ether.
9. The method for preparing the photochromic rare earth spiral according to claim 2, characterized in that: The developing solvents used in the column chromatography purification in steps 1, 2 and 3 are petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate is 3:
1.
10. The use of the photochromic rare earth spiral as claimed in claim 1, characterized in that: The method for preparing an anti-counterfeiting two-dimensional code with photochromic properties by using a photochromic rare earth spirosome is carried out in the following steps:
1. dissolving the synthesized photochromic rare earth spirosome in a tetrahydrofuran solution to obtain a photochromic rare earth spirosome solution; 2. forming a two-dimensional code pattern on a substrate; 3. Covering the photochromic rare earth spirosome solution obtained in step 1 on the two-dimensional code pattern; curing after irradiation with ultraviolet light of 350 to 370 nm for 5 to 10 minutes to obtain an anti-counterfeiting two-dimensional code with photochromic properties; 4. In the absence of ultraviolet light, the anti-counterfeiting QR code with photochromic properties is colorless, the information in the QR code pattern is fully displayed, and the information can be successfully read; under ultraviolet light, the photochromic rare earth spiral changes color and covers the covered part of the QR code pattern, resulting in an incomplete QR code and inability to read the information, forming a dynamic anti-counterfeiting effect.