Multi-color tunable responsive gel fluorescent materials, methods of making, using, tuning, and applications thereof

Abstract

The application belongs to the technical field of functional materials, and discloses a multi-color adjustable responsive gel fluorescent material, wherein a rare earth europium ion-2,6-pyridine dicarboxylic acid complex is used as a red fluorescent group, 5-amino salicylic acid is used as a blue-green fluorescent group, and gelatin is used as a gel matrix; under ultraviolet excitation, the fluorescent color of the responsive gel fluorescent material presents red, pink, pinkish white, white, light blue or blue-green. The gel material provided by the application not only introduces two kinds of light emitting centers, but also has a stimulation response; by changing the concentration of each component, changing the wavelength of excitation light, or adding acid or metal ions, the fluorescent color of the gel can be converted between red, pink, white, light blue and blue-green through one or more of the three ways, and this multi-dimensional regulation method is more conducive to application in the field of information storage or encryption anti-counterfeiting.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, and relates to a multicolor tunable responsive gel fluorescent material and its preparation method, usage method, regulation method and application. Background Technology

[0002] In recent years, information storage, encryption, and information security technologies have been widely applied in people's daily lives, economic fields, and the military. With the rapid development of information science and technology, the demand for information storage materials with high storage capacity and strong security is becoming increasingly urgent. Various technologies such as laser holography, nano-humidity sensing, and radio frequency identification have been applied to storage and encryption. However, these methods are generally complex, inconvenient to use, and expensive, which limits their widespread application in the field of information security.

[0003] Responsive fluorescent materials can switch fluorescence or change fluorescence color in response to external stimuli, showing potential for applications in advanced encryption and information storage. However, the performance of existing responsive fluorescent materials is already struggling to meet the rapidly evolving needs of information storage, primarily due to the difficulty in introducing and controlling multiple fluorescent groups. Therefore, the development of more reliable information storage materials remains crucial.

[0004] Gel materials exhibit a favorable matrix effect, allowing for the embedding of fluorescent groups such as carbon dots, quantum dots, dyes, and nanoparticles to construct multiple luminescent centers. Furthermore, as a soft material, gels possess self-supporting, shape-flexible, and easily processed properties compared to solid and liquid materials, thus offering greater application flexibility. Introducing fluorescent groups into gel matrices to construct responsive gel fluorescent materials, and modulating changes in fluorescence, phase state, color, and mechanical properties through external stimuli, can significantly enhance information storage and encryption capabilities, as well as substantially improve the security of information transmission.

[0005] However, the preparation process of the reported responsive gel fluorescent materials is complex, time-consuming, has a single emission color, is not easy to control, and has limited applications. There are no reports of multi-color tunable responsive gel fluorescent materials that can be used for information storage and encryption. Summary of the Invention

[0006] This invention addresses the technical problems of existing gel fluorescent materials, such as complex preparation processes, long processing times, single emission color, difficulty in control, and limited applications. It provides a multi-color tunable responsive gel fluorescent material that introduces two emission centers and exhibits stimulus responsiveness. By changing the concentration of each component, changing the wavelength of the excitation light, or adding one or more of the following methods, the fluorescent color of the gel can be switched between red, pink, off-white, white, light blue, and blue-green. This multi-dimensional control method is more conducive to applications in information storage or encryption and anti-counterfeiting fields.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a multi-color tunable responsive gel fluorescent material, wherein the responsive gel fluorescent material uses a rare earth europium ion-2,6-pyridine dicarboxylic acid complex as a red fluorescent group, 5-aminosalicylic acid as a blue-green fluorescent group, and gelatin as a gel matrix; under ultraviolet light excitation, the fluorescence color of the responsive gel fluorescent material is red, pink, off-white, white, light blue, or blue-green.

[0009] This invention introduces two fluorescent groups, 5-aminosalicylic acid (blue-green) and rare-earth europium ion-2,6-pyridinedicarboxylic acid complex (red), into a gel material. Gelatin is used as the gel matrix. By utilizing the gelling properties and encapsulation ability of gelatin for guest molecules, not only are the luminescence properties of rare-earth europium ion-2,6-pyridinedicarboxylic acid complex and 5-aminosalicylic acid unaffected, but the network structure formed by their intermolecular hydrogen bonds and electrostatic interactions can uniformly embed and fix these two luminescent centers, which is more conducive to the stability of gel luminescence and the precise control of multiple colors.

[0010] Secondly, the present invention provides a method for preparing the above-mentioned multicolor tunable responsive gel fluorescent material, comprising the following steps:

[0011] 1) Dissolve 2,6-pyridinedicarboxylic acid in an organic solvent to obtain an organic solution of 2,6-pyridinedicarboxylic acid, and then add a salt solution of rare earth europium ions to the organic solution of 2,6-pyridinedicarboxylic acid to obtain a mixed solution containing rare earth europium ions and a complex of 2,6-pyridinedicarboxylic acid.

[0012] 2) Dissolve 5-aminosalicylic acid in an organic solvent to obtain an organic solution containing 5-aminosalicylic acid;

[0013] 3) Under heating conditions, a mixed solution containing rare earth europium ions and a 2,6-pyridine dicarboxylic acid complex, an organic solution containing 5-aminosalicylic acid, and an aqueous solution of gelatin are mixed evenly and then cooled to room temperature to obtain a multicolor tunable responsive gel fluorescent material.

[0014] In one technical solution, the organic solvent is selected from N,N-dimethylformamide, dimethyl sulfoxide, methanol, ethanol, acetonitrile, or acetone.

[0015] In one technical solution, the concentration of europium ions in the rare earth europium ion salt solution is 1-100 mmol / L, and the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid organic solution is 1-600 mmol / L; the volume ratio of the rare earth europium ion salt solution to the 2,6-pyridinedicarboxylic acid organic solution is 1:1-3.

[0016] In one technical solution, the concentration of 5-aminosalicylic acid in the organic solution containing 5-aminosalicylic acid is 1 to 100 μmol / L; the volume ratio of the organic solution containing 5-aminosalicylic acid to the mixed solution containing rare earth europium ions and 2,6-pyridine dicarboxylic acid complex is 1 to 3:1.

[0017] In one technical solution, the concentration of gelatin in the aqueous solution of gelatin is 10-30 wt%; the volume ratio of the aqueous solution of gelatin to the mixed solution containing rare earth europium ions and 2,6-pyridine dicarboxylic acid complex is 1-5:1.

[0018] In preparing the gel material according to this invention, a rare earth europium salt solution and 2,6-pyridinedicarboxylic acid are first mixed in a specific ratio and concentration. Then, under heating conditions, this mixture and a 5-aminosalicylic acid organic solution are separately added to an aqueous gelatin solution and mixed thoroughly. This order of addition cannot be arbitrarily changed. If the rare earth europium salt solution is mixed with the 5-aminosalicylic acid organic solution first, the rare earth europium salt solution and 2,6-pyridinedicarboxylic acid cannot form a complex, and the gel will not exhibit red fluorescence. 5-Aminosalicylic acid has amino, carboxyl, and hydroxyl groups, all of which can coordinate with rare earth europium ions to form complexes. However, the excited state energy levels of 5-aminosalicylic acid and rare earth europium ions do not match, preventing energy transfer. In other words, changing the order of addition will prevent the resulting gel material from undergoing color conversion under ultraviolet light excitation.

[0019] During the experiments of this invention, other polymeric gels were tried as gel matrices, such as agarose gel, chitosan gel, and alginate gel, but none of them could achieve the above experimental results well, and the gel fluorescence could not be converted well. Therefore, gelatin is the preferred gel matrix.

[0020] During the experiments of this invention, several other rare earth ions with good inherent luminescence properties were also tried, such as terbium ions, dysprosium ions, and samarium ions. However, under the same conditions, the green fluorescence emitted by terbium ions overlapped with the blue-green fluorescence of 5-aminosalicylic acid, resulting in minimal color change in the gel. Gel materials prepared from dysprosium and samarium ions, on the other hand, did not exhibit the fluorescence of rare earth ions. Therefore, europium ions are preferred as the rare earth ion, resulting in gel materials with diverse fluorescence color variations.

[0021] During the experiments of this invention, other fluorescent dyes that do not require synthetic modification were also tried, but none of them could achieve the above experimental results well, and the gel fluorescence could not be converted well. Therefore, the preferred blue-green luminescent center is 5-aminosalicylic acid. The multicolor control of the gel material of this invention is based on the change of two different colors of fluorescence. Arbitrarily replacing the luminescent center and the gel matrix may result in the inability to control the fluorescence color of the gel.

[0022] In summary, the control of the gel material preparation process is particularly crucial in this invention. The type, concentration, ratio, and order of addition of raw materials all have a significant impact on whether a gel can be formed and the performance of the formed gel. This invention, by selecting suitable gel matrices and fluorescent groups and controlling specific preparation conditions and process parameters, enables the successful preparation of multicolor tunable responsive gel fluorescent materials.

[0023] Thirdly, the present invention provides a method for using the above-mentioned multicolor tunable responsive gel fluorescent material, wherein the responsive gel fluorescent material is used in one or more of the following environments:

[0024] 1) Under ultraviolet light excitation of 220–380 nm, the fluorescence color of this responsive gel fluorescent material is red, pink, off-white, white, light blue, or blue-green;

[0025] 2) When used under heating conditions, this responsive gel fluorescent material transforms into a solution state, but its luminescent properties remain unchanged;

[0026] 3) When acid or metal ions are present in the environment, the phase state of this responsive gel fluorescent material remains unchanged, but its red fluorescence under ultraviolet light excitation is weakened.

[0027] In one technical solution, the heating temperature is 45–100°C; the acid is hydrochloric acid, and the concentration of the acid used is 0.01–1 mol / L; the metal ion is Cu. 2+ When using it, the concentration of metal ions is 0.1 to 1.6 mmol / L.

[0028] The gel material prepared by this invention can achieve quenching of red fluorescence upon the addition of acid or metal ions. Other acids such as acetic acid, phosphoric acid, and acetic acid, and other metal ions such as Zn were tried during the experiment. 2+ Fe 3+ Co 2+ Mn 2+ Cd 2+ However, none of these methods could achieve the above experimental results satisfactorily, as the gel fluorescence did not convert well. Therefore, hydrochloric acid is preferred as the acid, and Cu is preferred as the metal ion. 2+ .

[0029] Fourthly, the present invention provides a method for regulating the above-mentioned multicolor tunable responsive gel fluorescent material, which is achieved through one or more of the following methods:

[0030] 1) By changing the ratio of rare earth europium ion-2,6-pyridinedicarboxylic acid complex to 5-aminosalicylic acid, or by changing the concentration of one or more of rare earth europium ions, 2,6-pyridinedicarboxylic acid or 5-aminosalicylic acid, the fluorescence color of the responsive gel fluorescent material can be controlled.

[0031] 2) By changing the wavelength of the excitation ultraviolet light, the fluorescence color of the responsive gel fluorescent material can be modulated;

[0032] 3) Add different concentrations of HCl and / or Cu to the gel system. 2+ The fluorescence color of this responsive gel fluorescent material can be controlled.

[0033] In the gel material of this invention, the maximum excitation wavelengths of the two fluorescent groups differ by 100 nm. Simultaneously, the energy transfer between 2,6-pyridinedicarboxylic acid and rare-earth europium ions can be interrupted by acids or metal ions. Therefore, by changing the concentration of each component, altering the wavelength of the excitation light, or adding acids (hydrochloric acid) or metal ions (Cu), the energy transfer can be achieved. 2+ One or more of these three methods can be used to control the fluorescent color of the gel to switch between red, pink, off-white, white, light blue, and blue-green.

[0034] Fifthly, the present invention also provides the application of the above-mentioned multi-color tunable responsive gel fluorescent material in information storage, encryption or anti-counterfeiting.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] (1) The gel material provided by the present invention not only introduces two light-emitting centers, but also has stimulation responsiveness. By changing the concentration of each component, changing the wavelength of the excitation light, or adding acid or metal ions, one or more of these three methods can be used to make the fluorescent color of the gel switch between red, pink, off-white, white, light blue and blue-green. This multi-dimensional regulation method is more conducive to its application in the fields of information storage or encryption and anti-counterfeiting.

[0037] (2) The fluorescent groups used in this invention are antibacterial drugs and rare earth elements, which have the advantages of high safety, good stability, high fluorescence intensity, long luminescence lifetime and high quantum yield. The gel matrix is ​​gelatin, which has high biological safety, good encapsulation effect, does not affect the performance of the luminescent group, and increases the security of information encryption.

[0038] (3) The preparation method of the present invention is simple. It only requires mixing several solutions evenly. The required materials are common and readily available. There is no need for complex processes such as chemical modification and synthesis. Moreover, the gel has excellent mechanical properties and processability, which broadens the application range of the material. Attached Figure Description

[0039] Figure 1 The image shows a scanning electron microscope (SEM) image of the gel fluorescent material prepared in Example 8.

[0040] Figure 2 Fluorescence photograph of the gel fluorescent material prepared in Example 9 under ultraviolet light (254nm+365nm).

[0041] Figure 3 The images show the heart-shaped, five-pointed star-shaped, and leaf-shaped gel fluorescent material prepared in Example 10 under sunlight and ultraviolet light (254nm, 365nm, 254nm+365nm).

[0042] Figure 4 The images show the gel fluorescent material prepared in Example 11 under sunlight and ultraviolet light (254nm, 365nm, 254nm+365nm) before and after heating.

[0043] Figure 5 The images show the gel fluorescent material prepared in Example 12 under sunlight and ultraviolet light (254nm, 365nm, 254nm+365nm) before and after the addition of HCl.

[0044] Figure 6 This is a photograph of the encryption and decryption process of the digital password stored in the gel sheet array in Example 13.

[0045] Figure 7 The images show the encryption and decryption process of the pattern information stored in the gel in Example 14, and the multiple encryption and decryption using HCl. Detailed Implementation

[0046] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the test methods in the following embodiments are conventional methods.

[0047] Example 1

[0048] Take 100 μL of a 0.1 mol / L europium chloride aqueous solution in a test tube, then add 200 μL of a 0.1 mol / L dimethyl sulfoxide solution of 2,6-pyridinedicarboxylic acid and mix thoroughly. At 60 °C, add the above mixed solution and 100 μL of a 0.1 mmol / L dimethyl sulfoxide solution of 5-aminosalicylic acid to a 1 mL 15 wt% gelatin aqueous solution and mix thoroughly. Cool to room temperature to form a yellow gel, which is the multicolor tunable responsive gel fluorescent material of this invention.

[0049] Example 2

[0050] Take 100 μL of a 0.1 mol / L europium chloride aqueous solution in a test tube, then add 300 μL of a 0.1 mol / L dimethyl sulfoxide solution of 2,6-pyridinedicarboxylic acid and mix thoroughly. At 60 °C, add the above mixed solution and 100 μL of a 0.1 mmol / L dimethyl sulfoxide solution of 5-aminosalicylic acid to a 1 mL 15 wt% gelatin aqueous solution and mix thoroughly. Cool to room temperature to form a yellow gel, which is the multicolor tunable responsive gel fluorescent material of this invention.

[0051] Example 3

[0052] Take 100 μL of a 0.1 mol / L europium chloride aqueous solution in a test tube, then add 200 μL of a 0.1 mol / L dimethyl sulfoxide solution of 2,6-pyridinedicarboxylic acid and mix thoroughly. At 60 °C, add the above mixed solution and 200 μL of a 0.1 mmol / L dimethyl sulfoxide solution of 5-aminosalicylic acid to a 1 mL 15 wt% gelatin aqueous solution and mix thoroughly. Cool to room temperature to form a yellow gel-like substance, which is the multicolor tunable responsive gel fluorescent material of this invention.

[0053] Example 4

[0054] Take 100 μL of a 0.1 mol / L europium chloride aqueous solution in a test tube, then add 200 μL of a 0.1 mol / L dimethyl sulfoxide solution of 2,6-pyridinedicarboxylic acid and mix thoroughly. At 60 °C, add the above mixed solution and 100 μL of a 0.1 mmol / L dimethyl sulfoxide solution of 5-aminosalicylic acid to a 1 mL 20 wt% gelatin aqueous solution and mix thoroughly. Cool to room temperature to form a yellow gel, which is the multicolor tunable responsive gel fluorescent material of this invention.

[0055] Example 5

[0056] Take 100 μL of a 0.1 mol / L europium chloride aqueous solution in a test tube, then add 200 μL of a 0.1 mol / L dimethyl sulfoxide solution of 2,6-pyridinedicarboxylic acid and mix thoroughly. At 60 °C, add the above mixed solution and 200 μL of a 0.1 mmol / L dimethyl sulfoxide solution of 5-aminosalicylic acid to a 1 mL 20 wt% gelatin aqueous solution and mix thoroughly. Cool to room temperature to form a yellow gel-like substance, which is the multicolor tunable responsive gel fluorescent material of this invention.

[0057] Example 6

[0058] Take 100 μL of a 0.1 mol / L europium chloride aqueous solution in a test tube, then add 300 μL of a 0.1 mol / L dimethyl sulfoxide solution of 2,6-pyridinedicarboxylic acid and mix thoroughly. At 60 °C, add the above mixed solution and 100 μL of a 0.1 mmol / L dimethyl sulfoxide solution of 5-aminosalicylic acid to a 1 mL 20 wt% gelatin aqueous solution and mix thoroughly. Cool to room temperature to form a yellow gel, which is the multicolor tunable responsive gel fluorescent material of this invention.

[0059] Example 7

[0060] Take 100 μL of a 0.1 mol / L europium chloride aqueous solution in a test tube, then add 300 μL of a 0.1 mol / L dimethyl sulfoxide solution of 2,6-pyridinedicarboxylic acid and mix thoroughly. At 60 °C, add the above mixed solution and 200 μL of a 0.1 mmol / L dimethyl sulfoxide solution of 5-aminosalicylic acid to a 1 mL 20 wt% gelatin aqueous solution and mix thoroughly. Cool to room temperature to form a yellow gel, which is the multicolor tunable responsive gel fluorescent material of this invention.

[0061] Example 8

[0062] Take 100 μL of a 0.1 mol / L europium chloride aqueous solution in a test tube, then add 300 μL of a 0.1 mol / L dimethyl sulfoxide solution of 2,6-pyridinedicarboxylic acid and mix thoroughly. At 60 °C, add the above mixed solution and 200 μL of a 0.1 mmol / L dimethyl sulfoxide solution of 5-aminosalicylic acid to a 1 mL 20 wt% gelatin aqueous solution and mix thoroughly. Cool to room temperature to form a yellow gel, which is the multicolor tunable responsive gel fluorescent material of this invention.

[0063] Figure 1 This is an electron microscope image of the gel fluorescent material in this embodiment. Figure 1 The image shows that the gel has an intertwined network structure.

[0064] Example 9: Fluorescence color of the gel material under ultraviolet light excitation

[0065] (I) Experimental Materials

[0066] Raw materials: The rare earth salt was europium chloride, with europium ion concentrations of 100, 50, 10, 5, 2, and 1 mmol / L; the concentrations of 2,6-pyridinedicarboxylic acid were 200, 100, 20, 10, 4, and 2 mmol / L; the concentrations of 5-aminosalicylic acid were 1, 2, 5, 10, 50, and 100 μmol / L; the concentration of gelatin was 15 wt%; and the organic solvent was dimethyl sulfoxide. Six gel fluorescent materials were prepared according to the method in Example 1, with a total volume of 1 mL. The concentrations of each component in the six gel fluorescent materials are shown in Table 1.

[0067] Table 1. Concentrations of each component in the six gel fluorescent materials obtained in Example 9.

[0068]

[0069] (II) Experimental Methods

[0070] The above-mentioned gel fluorescent materials were placed under ultraviolet light (254nm + 365nm), and the results are shown in the figure. Figure 2 .Depend on Figure 2 It is known that by adjusting the concentration of fluorescent group components, the fluorescent color of the gel material can be red, pink, off-white, white, light blue, or blue-green.

[0071] Example 10: Modulating the fluorescence color of the gel fluorescent material by changing the wavelength of the excitation ultraviolet light.

[0072] (I) Experimental Materials

[0073] Materials: The rare earth salt was europium chloride, with europium ion concentrations of 20, 10, and 5 mmol / L; the concentrations of 2,6-pyridinedicarboxylic acid were 40, 20, and 10 mmol / L; the concentration of 5-aminosalicylic acid was 2 μmol / L; the organic solvent was dimethyl sulfoxide; the concentration of gelatin was 15 wt%; and the total volume was 1 mL.

[0074] (II) Experimental Methods: Three types of gel fluorescent materials were prepared according to the method in Example 1. The concentrations of each component in the three types of gel fluorescent materials are shown in Table 2. Each gel was molded into heart, pentagram, and leaf shapes, with three sizes for each shape, and placed under sunlight and ultraviolet light (254nm, 365nm, and 254nm+365nm).

[0075] Table 2. Concentrations of each component in the three gel fluorescent materials obtained in Example 10.

[0076]

[0077] When excited by ultraviolet light (254nm, 365nm, 254nm+365nm), the fluorescence colors of the gel fluorescent material are as follows: Figure 3 As shown. By Figure 3It is known that the gel fluorescent material is yellow under sunlight, red under 254nm ultraviolet light, blue under 365nm ultraviolet light, and pink or pinkish-white under 254nm+365nm ultraviolet light. This is because, under 254nm ultraviolet excitation, the rare-earth europium ion-2,6-pyridinedicarboxylic acid complex in the gel fluorescent material emits red fluorescence. Under 365nm ultraviolet excitation, 5-aminosalicylic acid in the gel fluorescent material emits blue fluorescence. Under co-excitation by 254nm and 365nm ultraviolet light, the color of the gel changes to pink or pinkish-white after mixing red and green fluorescence of different intensities, indicating that the fluorescence color of the gel fluorescent material can be controlled by changing the wavelength of the excitation ultraviolet light.

[0078] Example 11 Temperature Response of Gel Fluorescent Materials

[0079] (I) Experimental Materials

[0080] Materials: The rare earth salt is europium chloride, with a europium ion concentration of 20 mmol / L, a 2,6-pyridinedicarboxylic acid concentration of 40 mmol / L, a 5-aminosalicylic acid concentration of 10 μmol / L, a gelatin concentration of 15 wt%, and a dimethyl sulfoxide organic solvent. The total volume is 1.5 mL.

[0081] (II) Experimental methods: After preparing the gel according to the method of Example 1, it was heated at 60°C until it became a solution, and then placed under sunlight and ultraviolet light (254nm, 365nm, 254nm+365nm). The fluorescent material of the gel before heating was used as a control.

[0082] The gel fluorescent material before heating and the solution material after heating were excited by ultraviolet light (254nm, 365nm, 254nm+365nm), respectively. The fluorescence color of the gel fluorescent material is shown in [reference needed]. Figure 4 As shown in the figure, the gel becomes a solution after heating, but remains yellow under sunlight, and its fluorescence under ultraviolet light shows no significant change. Under heating conditions, the hydrogen bonds and electrostatic interactions between gelatin molecules break, the gel's network structure disintegrates, and the gel transforms into a solution, indicating that this gel fluorescent material is temperature-responsive.

[0083] Example 12 Gel material for use with HCl and / or Cu 2+ response

[0084] (I) Experimental Materials

[0085] Materials: The rare earth salt is europium chloride, with a europium ion concentration of 20 mmol / L; the concentration of 2,6-pyridinedicarboxylic acid is 40 mmol / L; the concentration of 5-aminosalicylic acid is 10 μmol / L; the concentration of gelatin is 15 wt%; the organic solvents are dimethyl sulfoxide, 0.1 mol / L HCl solution, and 0.1 mol / L copper chloride aqueous solution, with a total volume of 1.5 mL.

[0086] (II) Experimental methods: Following the method in Example 1, 100 μL of HCl solution, 100 μL of copper chloride aqueous solution, and 50 μL each of HCl solution and copper chloride aqueous solution were added during the gel preparation process. After mixing evenly and cooling to room temperature to form a gel, the gel was placed under sunlight and ultraviolet light (254 nm, 365 nm, 254 nm + 365 nm) to obtain three kinds of gel fluorescent materials. The gel fluorescent material without acid or metal ions was used as a control.

[0087] Gel fluorescent materials without added acid or metal ions, and gel fluorescent materials with added HCl solution, were excited by ultraviolet light (254nm, 365nm, and 254nm+365nm), respectively. The fluorescence colors of the gel fluorescent materials are shown in [the figure]. Figure 5 The fluorescence color of the gel fluorescent material containing copper chloride aqueous solution and simultaneously HCl solution and copper chloride aqueous solution under the above ultraviolet light is the same. Figure 5 As shown in the figure, the gel was treated with the addition of HCl or Cu. 2+ Afterwards, it remains yellow under sunlight, but its red fluorescence is quenched under 254nm ultraviolet light, while having no significant effect on its blue fluorescence under 365nm ultraviolet light. In HCl or Cu... 2+ In the presence of Cu, energy transfer between 2,6-pyridinedicarboxylic acid and rare earth europium ions in the complex is interrupted, and the red fluorescence of the gel is quenched, indicating that the gel fluorescent material is resistant to HCl and Cu. 2+ It is responsive.

[0088] Example 13: Gel materials applied to information storage and encryption

[0089] (I) Experimental Materials

[0090] Materials: The concentrations of rare earth europium ions were 20 and 5 mmol / L, the concentrations of 2,6-pyridinedicarboxylic acid were 40 and 10 mmol / L, the concentration of 5-aminosalicylic acid was 2 μmol / L, the organic solvent was dimethyl sulfoxide, the rare earth salt was europium chloride, the concentration of gelatin was 15 wt%, and the total volume was 1 mL. Three types of gel fluorescent materials were prepared according to the method in Example 1. The concentrations of each component in the three types of gel fluorescent materials are shown in Table 3.

[0091] Table 3. Concentrations of each component in the three gel fluorescent materials obtained in Example 12

[0092]

[0093] (II) Experimental Methods: Three gel sheet arrays were prepared using three different gel fluorescent materials. The digital password was stored in the arrays and then decrypted under ultraviolet light (254nm, 365nm, and 254nm+365nm). The results are shown in [Figure Number]. Figure 6 .

[0094] Depend on Figure 6 It can be seen that the gel array can read the number "438" under 254nm ultraviolet light, and still read the encrypted number "888" under 365nm ultraviolet light. However, it can read the number "110" under 254nm+365nm ultraviolet light. Combining the two numbers gives the complete password information, indicating that the gel fluorescent material can be used for information storage and encryption.

[0095] Example 14: Application of Gel Fluorescent Materials in Multidimensional Information Storage and Encryption

[0096] (I) Experimental Materials

[0097] Materials: The rare earth salt was europium chloride, with europium ion concentrations of 5 mmol / L, 2,6-pyridinedicarboxylic acid concentrations of 10 mmol / L, and 5-aminosalicylic acid concentrations of 2 μmol / L. The organic solvent was dimethyl sulfoxide, and the gelatin concentration was 15 wt%, with a total volume of 1 mL. 0.1 mol / L HCl solution and 0.1 mol / L copper chloride aqueous solution were also used. Two types of gel fluorescent materials were prepared according to the method in Example 1. The concentrations of each component in the two gel fluorescent materials are shown in Table 4.

[0098] Table 4. Concentrations of each component in the two gel fluorescent materials obtained in Example 13

[0099]

[0100] (II) Experimental Methods: Two types of gel fluorescent materials were prepared into gemstone shapes, and the pattern information was stored in the gel. Based on this, HCl or Cu... 2+ The alphabetic code was then stored in a gel and decrypted under ultraviolet light (254nm, 365nm, and 254nm+365nm), respectively. The results are shown below. Figure 7 .

[0101] Depend on Figure 7 It is known that the original gem-shaped gel fluorescent material can be read as a red heart pattern under 254nm ultraviolet light, but not under 365nm ultraviolet light, and can be read as a white heart pattern under 254nm+365nm ultraviolet light. This can be further verified by using HCl or Cu... 2+After re-encryption, the gel fluorescent material can be read under 254nm or 254nm+365nm ultraviolet light, indicating that the gel fluorescent material can be used for multi-dimensional storage and encryption of information.

[0102] The embodiments described above are merely preferred embodiments of the present invention and are only used to explain the present invention. They are not intended to limit the scope of the present invention. For those skilled in the art, other implementation methods can be easily made by substitution or modification based on the technical content disclosed in this specification. Therefore, all changes and improvements made on the principle of the present invention should be included within the scope of the patent application of the present invention.

Claims

1. A multicolor tunable responsive gel fluorescent material, characterized in that, The responsive gel fluorescent material uses rare earth europium ion-2,6-pyridine dicarboxylic acid complex as a red fluorescent group, 5-aminosalicylic acid as a blue-green fluorescent group, and gelatin as a gel matrix; under ultraviolet light excitation, the fluorescence color of the responsive gel fluorescent material is red, pink, off-white, white, light blue, or blue-green.

2. The method for preparing a multicolor tunable responsive gel fluorescent material according to claim 1, characterized in that, Includes the following steps: 1) Dissolve 2,6-pyridinedicarboxylic acid in an organic solvent to obtain an organic solution of 2,6-pyridinedicarboxylic acid, and then add a salt solution of rare earth europium ions to the organic solution of 2,6-pyridinedicarboxylic acid to obtain a mixed solution containing rare earth europium ions-2,6-pyridinedicarboxylic acid complex. 2) Dissolve 5-aminosalicylic acid in an organic solvent to obtain an organic solution containing 5-aminosalicylic acid; 3) Under heating conditions, a mixed solution containing rare earth europium ion-2,6-pyridine dicarboxylic acid complex, an organic solution containing 5-aminosalicylic acid, and an aqueous solution of gelatin are mixed evenly and then cooled to room temperature to obtain a multicolor tunable responsive gel fluorescent material.

3. The preparation method according to claim 2, characterized in that, The organic solvent is selected from one of N,N-dimethylformamide, dimethyl sulfoxide, methanol, ethanol, acetonitrile, or acetone.

4. The preparation method according to claim 2, characterized in that, The concentration of europium ions in the rare earth europium ion salt solution is 1–100 mmol / L, and the concentration of 2,6-pyridinedicarboxylic acid in the 2,6-pyridinedicarboxylic acid organic solution is 1–600 mmol / L; the volume ratio of the rare earth europium ion salt solution to the 2,6-pyridinedicarboxylic acid organic solution is 1:1–3.

5. The preparation method according to claim 2, characterized in that, The concentration of 5-aminosalicylic acid in the organic solution containing 5-aminosalicylic acid is 1 to 100 μmol / L; the volume ratio of the organic solution containing 5-aminosalicylic acid to the mixed solution containing rare earth europium ion-2,6-pyridinedicarboxylic acid complex is 1 to 3:

1.

6. The preparation method according to claim 2, characterized in that, The concentration of gelatin in the aqueous solution of the gelatin is 10-30 wt%; the volume ratio of the aqueous solution of the gelatin to the mixed solution containing rare earth europium ion-2,6-pyridine dicarboxylic acid complex is 1-5:

1.

7. The method of using the multicolor tunable responsive gel fluorescent material according to claim 1, characterized in that, The responsive gel fluorescent material is used in one or more of the following environments: 1) Under ultraviolet light excitation of 220~380nm, the fluorescence color of the responsive gel fluorescent material is red, pink, off-white, white, light blue or blue-green; 2) When used under heating conditions, the responsive gel fluorescent material transforms into a solution state, while its luminescent properties remain unchanged; 3) When acid or metal ions are present in the environment, the phase state of the responsive gel fluorescent material remains unchanged, but the red fluorescence under ultraviolet light excitation is weakened.

8. The method of use according to claim 7, characterized in that, The heating temperature is 45–100°C; the acid is hydrochloric acid, and the concentration of the acid used is 0.01–1 mol / L; the metal ion is Cu. 2+ When using it, the concentration of metal ions is 0.1 to 1.6 mmol / L.

9. The method for regulating a multicolor tunable responsive gel fluorescent material according to claim 1, characterized in that, This can be achieved through one or more of the following methods: 1) By changing the ratio of rare earth europium ion-2,6-pyridinedicarboxylic acid complex to 5-aminosalicylic acid, or by changing the concentration of one or more of rare earth europium ions, 2,6-pyridinedicarboxylic acid or 5-aminosalicylic acid, the fluorescence color of the responsive gel fluorescent material can be controlled. 2) By changing the wavelength of the excitation ultraviolet light, the fluorescence color of the responsive gel fluorescent material can be modulated; 3) Add different concentrations of HCl and / or Cu to the gel system. 2+ The fluorescence color of the responsive gel fluorescent material is controlled.

10. The application of the multicolor tunable responsive gel fluorescent material of claim 1 in information storage, encryption, or anti-counterfeiting.

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