A dual-wavelength excited Schiff base optical switch material, photochromic material, and preparation method and application thereof

Abstract

This invention discloses a dual-wavelength excited Schiff base photo-switching material, a photochromic material, its preparation method, and its applications. The Schiff base photo-switching material of this invention is obtained by reflux reaction of 4-halosalicylaldehyde and a primary amine. Due to the p-π conjugation of the halogen atom with the benzene ring, the electron cloud density at the para position of the halogen atom is slightly higher than that at the meta position, making it easier for the Schiff base to undergo enol-keto configuration conversion, thus improving the luminescence efficiency of the material. Simultaneously, the amino group in the primary amine is not directly connected to the benzene ring, avoiding the conjugation of the C=N bond with the benzene ring on the primary amine side, improving the switching speed, and thus reducing the aggregation-induced fluorescence quenching phenomenon of the material molecules. The Schiff base photo-switching material and photochromic material provided by this invention can be applied in two-dimensional or three-dimensional display devices, light-controlled switching elements, multi-emissivity anti-counterfeiting materials, three-dimensional data storage, and other fields.

Description

Technical Field

[0001] This invention relates to the field of organic light-emitting materials technology, specifically to a dual-wavelength excited Schiff base photo-switching material, a photochromic material, its preparation method, and its application. Background Technology

[0002] Light is a high-speed, high-resolution, and environmentally friendly form of energy that can serve as a driving force for various advanced functional materials, among which reversible photoresponsive functional materials are one. These materials can be reversed between two isomers with different absorption wavelengths, exhibiting a switching effect. Therefore, reversible photoresponsive functional materials have been widely applied in fields such as optical data storage, optoelectronic devices, and bioimaging.

[0003] Schiff bases, also known as Schiff bases or Schiff alkalis, are a class of organic compounds containing imine or methylimine characteristic groups (-CRC=N-). They are generally synthesized by the condensation of amines with activated carbon groups. Due to the lone pair of electrons in the hybrid orbitals of the nitrogen atom, Schiff bases have important applications and research value in chemistry, biology, and other fields. The synthesis of Schiff bases typically involves a condensation reaction between an active group and an amine. Because of its flexible selectivity, slight changes in the groups and chemical environment of the raw materials can produce Schiff base products with different properties and structures, thus offering unique applications. This condensation reaction method can meet the needs of preparing various Schiff bases, such as bidentate Schiff bases (condensation of diamines with alkalis), monodentate Schiff bases (condensation of monoalkalis with monoamines), isobis-Schiff bases, asymmetric Schiff bases, etc. Schiff bases and their complexes, due to their excellent catalytic and liquid crystal properties, have significant research value and application potential in molecular catalysis, medicinal chemistry, analytical chemistry, spectroscopy, displays, and other fields. Some types of Schiff base materials exhibit photochromism, meaning they can reversibly change their color under illumination. This is due to an intramolecular proton transfer (ESIPT) process. Taking salicylaldehyde aniline (SA) as an example, under illumination, the initial structure of the SA molecule is excited. Through intramolecular hydrogen bonds, protons in the acidic phenolic hydroxyl group readily transfer to the nearby basic nitrogen atom, resulting in a rapid ESIPT process. This leads to a change in the molecular valence structure and photochromism. This photochromic property of Schiff bases has significant application prospects in information storage, memory simulation, optical computing, anti-counterfeiting, and information display. The isomers of photochromic Schiff base materials before and after the color change exhibit different fluorescence properties; these reversible photofluorescent color-changing materials are also known as "light-switching" materials. Light-switching Schiff base materials can serve as volumetric 3D imaging media for generating spatial voxels, making them highly valuable for research in the field of volumetric 3D display technology.

[0004] Volumetric 3D display is a stereoscopic display technology that allows direct observation of 3D images with physical depth. It offers numerous advantages, including lifelike images, full-view capability, multi-angle viewing, simultaneous observation by multiple users, and real-time interaction. Volumetric 3D display constructs a series of luminous voxels in the imaging space within a very short time using two light sources, and utilizes the persistence of vision to achieve the display. This requires materials capable of volumetric 3D display to emit light at the intersection when excited by two light sources of different wavelengths, thus enabling free control of the voxels. Therefore, reversible photoresponse materials with single-wavelength control and slow response speeds are difficult to use in the field of volumetric 3D display.

[0005] Currently, in the field of inorganic materials, it has been found that volumetric 3D displays can be achieved in rare-earth-doped fluoride glasses. However, the size of such solid media is difficult to increase significantly, which cannot meet the requirements for screen-level volumetric 3D displays. In the field of organic materials, reversible photoresponsive materials show promise as media for volumetric 3D displays, but their slow response speed makes it difficult for most photochromic materials to be applied in the field of volumetric 3D displays.

[0006] Organic small molecules possess advantages such as simple structure, good luminescence properties, ease of purification, and the ability to fabricate optoelectronic devices using vacuum evaporation. For example, Schiff bases, due to their excellent coordination ability and readily available structural modification properties, are widely used in optoelectronic materials and chemical information sensing. However, while organic small molecule luminescent materials typically exhibit excellent fluorescence properties in solution, in the solid state, due to strong intermolecular interactions, they are prone to aggregation-induced fluorescence quenching, which reduces the luminescence efficiency of the material and consequently affects the performance of the corresponding light-emitting devices, thus limiting their application scenarios. Summary of the Invention

[0007] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a Schiff base photoswitching material, which is a compound having the general chemical formula (1):

[0008]

[0009] In formula (I), X is selected from F, Cl, or Br; R is -C n H 2n - Carbon chain, n is a positive integer from 1 to 6.

[0010] Preferably, the Schiff base photoswitching material is any one of the following compounds:

[0011]

[0012]

[0013] Another object of the present invention is to provide a method for preparing the above-mentioned Schiff base photoswitching material, comprising the following steps:

[0014] Compound A (4-halosalicylaldehyde), compound B (primary amine), and compound C (organic solvent 1) were sequentially added to a reaction flask. The mixture was stirred and heated to 78–90 °C until reflux was achieved. After the reaction was carried out under the controlled temperature, the mixture was cooled to allow crystals to precipitate, filtered, washed, and dried to obtain the target product D.

[0015] In the above-mentioned preparation method of Schiff base photo-switching material, the primary amine is selected from 1-phenylethylamine, α-methylbenzylamine, 3-phenylpropylamine, and 1-methyl-3-phenylpropylamine;

[0016] The organic solvent 1 is selected from methanol, ethanol, tetrahydrofuran, 1,4-dioxane, and toluene;

[0017] The ratio of raw materials used is: 4-halosalicylaldehyde: primary amine = 1 mol: (1.0~1.2) mol, 4-halosalicylaldehyde: solvent = 1 g: (3~5) mL;

[0018] The reaction time is 2 to 4 hours.

[0019] Another object of the present invention is to provide a photochromic material, which is obtained by mixing and curing the above-mentioned Schiff base photoswitching material with epoxy resin; the mass ratio of Schiff base photoswitching material to epoxy resin is 1:(5000-10000).

[0020] Another object of the present invention is to provide a method for preparing the above-mentioned photochromic material, comprising the following steps:

[0021] Weigh out the Schiff base photo-switching material and dissolve it in organic solvent 2 to prepare a solution. Pour the solution into the epoxy resin liquid, mix it evenly, pour the reaction solution into the mold, and after curing and demolding, the product is obtained.

[0022] The organic solvent 2 is selected from dichloromethane, cyclohexane, tetrahydrofuran, and n-hexane; the Schiff base photoswitching material is prepared with organic solvent 2 in a solution of 0.001–10 mg / mL.

[0023] In the above-mentioned method for preparing photochromic materials, the epoxy resin solution is obtained by mixing epoxy resin A and epoxy resin B in a mass ratio of 1 to 10:1, preferably in a mass ratio of 3:1.

[0024] The epoxy resin A is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin and hydrogenated bisphenol A epoxy resin;

[0025] The epoxy resin B adhesive is an anhydride-based resin curing agent; preferably, the epoxy resin B adhesive is at least one of the following anhydrides: methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, etc.

[0026] The preferred reaction solution is cured at room temperature for 20–30 hours.

[0027] The final object of the present invention is to provide the application of the above-mentioned Schiff base photo-switching material or the above-mentioned photochromic material in three-dimensional imaging, preferably in the preparation of bulk three-dimensional display materials.

[0028] In the above application technical solution, the material is irradiated with an isomer excitation light source and a color-changing excitation light source, and a photopixel point is formed at the intersection of the isomer excitation light source and the color-changing excitation light source.

[0029] Controlling the scanning path and scanning speed of the isomer excitation source and the color-changing excitation source enables three-dimensional imaging in materials;

[0030] Preferably, the excitation source for the isomer is ultraviolet light; the color-changing excitation source is blue visible light.

[0031] Preferably, in the above application technical solution, the wavelength of the ultraviolet light is 350nm to 420nm, and the wavelength of the blue visible light is 450nm to 500nm;

[0032] The material is irradiated with ultraviolet light and blue visible light, and the ultraviolet light and blue visible light converge within the material, forming a yellow photon dot at the convergence point. By controlling the scanning path and scanning speed of the ultraviolet light and blue visible light, a three-dimensional image of yellow fluorescence is formed in the material.

[0033] The beneficial effects of this invention are:

[0034] The present invention provides a method for preparing a dual-wavelength excited Schiff base photoswitching material, which has low raw material cost, simple process flow and is conducive to industrial application.

[0035] The Schiff base photoswitching material provided in this invention exhibits the following performance characteristics in epoxy resin: it emits yellow fluorescence under co-excitation by ultraviolet light and 450nm blue light, and recovers rapidly after visible light stimulation. This invention uses 4-halosalicylaldehyde and primary amine as raw materials to prepare the Schiff base photoswitching material. Due to the p-π conjugation of the halogen atom with the benzene ring, the electron cloud density at the para position of the halogen atom is slightly higher than that at the meta position, making it easier for the Schiff base to undergo enol-keto configuration conversion, thus improving the luminescence efficiency of the material. Simultaneously, the amino group in the primary amine is not directly connected to the benzene ring, avoiding C=N bond conjugation with the benzene ring on the primary amine side, improving the switching speed, and thus reducing the occurrence of aggregation-induced fluorescence quenching.

[0036] The Schiff base photosensitive material provided in this invention can be applied to two-dimensional or three-dimensional display devices, light-controlled switching elements, and multi-emissivity anti-counterfeiting materials. The epoxy resin prepared using this Schiff base photosensitive material exhibits high transparency, good stability, and good reversibility. As a fast-response photosensitive material, it can be applied to two-dimensional or volumetric three-dimensional displays, multi-security anti-counterfeiting, and three-dimensional data storage.

[0037] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0038] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0039] Figure 1 This is a flowchart of the preparation process of the Schiff base photoluminescence material of the present invention.

[0040] Figure 2 This is the absorption spectrum of the Schiff base prepared from 4-chlorosalicylaldehyde and α-methylbenzylamine in Example 2 of this invention.

[0041] Figure 3 This is the 1H NMR spectrum of the Schiff base material prepared by 4-chlorosalicylaldehyde and α-methylbenzylamine in Example 2 of this invention.

[0042] Figure 4 This is an image of the intersection emission point of the Schiff base photoswitch in epoxy resin during dual-wavelength excitation, as described in Embodiment 2 of the present invention.

[0043] Figure 5 This is a three-dimensional imaging image of the Schiff base photoswitch in epoxy resin under dual-wavelength excitation, as described in Embodiment 2 of the present invention. Detailed Implementation

[0044] The embodiments of the present invention are described in detail below, and the embodiments described with reference to the accompanying drawings are exemplary.

[0045] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0046] The dual-wavelength excited Schiff base photoswitching material of the present invention has the general chemical formula (1):

[0047]

[0048] In formula (I), X is selected from F, Cl, or Br; R is -C n H 2n - Carbon chain, n is a positive integer from 1 to 6.

[0049] The preparation method of the Schiff base photoswitching material shown in formula (I) specifically includes the following steps (flowchart shown). Figure 1 As shown):

[0050] 4-Halosalicylaldehyde (compound A), primary amine (compound B), and solvent (compound C) were added sequentially to a reaction flask, stirred, and heated to 78–90°C (preferably 80–85°C) until reflux was reached. The reaction was maintained at this temperature for 2–4 hours, then cooled, allowed to crystallize, filtered, washed, and dried to obtain the target product (compound D). The reaction equation is as follows:

[0051]

[0052] In the above chemical reaction, the amounts of each raw material are as follows: 4-halosalicylaldehyde:solvent = 1 g:(3-5) mL, 4-halosalicylaldehyde:primary amine = 1 mmol:(1.0-1.2) mmol. The solvent is one of methanol, ethanol, tetrahydrofuran, 1,4-dioxane, or toluene. The primary amine can be selected from 1-phenylethylamine (CAS No.: 64-04-0), 3-phenylpropylamine (CAS No.: 2038-57-5), 1-methyl-3-phenylpropylamine (CAS No.: 22374-89-6), or α-methylbenzylamine (CAS No.: 3886-69-9).

[0053] The aforementioned Schiff base photoswitching material uses epoxy resin as the medium and can be prepared together with epoxy resin as a photochromic material. The preparation method includes the following steps:

[0054] Hydrogenated bisphenol A epoxy resin (epoxy resin A, CAS No.: 30583-72-3) and epoxy resin B (CAS No.: 11070-44-3) were mixed evenly at a mass ratio of 3:1 to obtain epoxy resin for later use. Schiff base photosensitive material was weighed and dissolved in dichloromethane to prepare a solution, which was then poured into the epoxy resin solution. After mixing evenly, the solution was poured into a mold and cured at room temperature for 24 hours. After demolding, the Schiff base photochromic material was obtained. The mass ratio of Schiff base photosensitive material to epoxy resin was 1:(5000~10000).

[0055] The Schiff base photoswitching materials of Examples 1-6 and the photochromic materials of Examples 7-12 were prepared according to the above method:

[0056] Example 1: Preparation of Schiff base photoswitching materials

[0057] The specific synthesis steps of the Schiff base provided by this invention are as follows:

[0058] 1.40 g of 4-fluorosalicylaldehyde, 1.21 g of 1-phenylethylamine, and 3 mL of ethanol were added sequentially to a flask. The mixture was stirred and heated to 85 °C and then refluxed. The reaction was maintained at this temperature for 4 h. The mixture was then cooled to 0 °C to precipitate a solid. The precipitate was filtered and washed three times with cold ethanol to obtain the target product.

[0059] Example 2: Preparation of Schiff base photoswitching materials

[0060] The specific synthesis steps of the Schiff base provided by this invention are as follows:

[0061] 1.56 g of 4-chlorosalicylaldehyde, 1.21 g of α-methylbenzylamine, and 5 mL of ethanol were added sequentially to a flask. The mixture was stirred and heated to 85 °C, then refluxed. The reaction was maintained at this temperature for 2 h. The mixture was then cooled to 0 °C, and a solid precipitated. The precipitate was filtered and washed three times with cold ethanol to obtain the target product. The absorption spectrum and 1H NMR spectrum of the product are shown below. Figure 2 and Figure 3 As shown in the figure, the test results indicate that the product was synthesized correctly.

[0062] Example 3: Preparation of Schiff base photoswitching materials

[0063] The specific synthesis steps of the Schiff base provided by this invention are as follows:

[0064] 2.01 g of 4-bromosalicylic acid, 1.45 g of α-methylbenzylamine, and 5 mL of ethanol were added sequentially to a flask. The mixture was stirred and heated to 85 °C and then refluxed. The reaction was maintained at this temperature for 2 h. The mixture was then cooled to 0 °C to precipitate a solid. The precipitate was filtered and washed three times with cold ethanol to obtain the target product.

[0065] Example 4: Preparation of Schiff base photoswitching materials

[0066] The specific synthesis steps of the Schiff base provided by this invention are as follows:

[0067] 1.56 g of 4-chlorosalicylaldehyde, 1.45 g of 1-phenylethylamine, and 5 mL of ethanol were added sequentially to a flask. The mixture was stirred and heated to 80 °C and then refluxed. The reaction was maintained at this temperature for 2 h. The mixture was then cooled to 0 °C to precipitate a solid. The precipitate was filtered and washed three times with cold ethanol to obtain the target product.

[0068] Example 5: Preparation of Schiff base photoswitching materials

[0069] The specific synthesis steps of the Schiff base provided by this invention are as follows:

[0070] 1.56 g of 4-chlorosalicylaldehyde, 1.62 g of 1-methyl-3-phenylpropanamine, and 5 mL of ethanol were added sequentially to a flask. The mixture was stirred and heated to 80 °C and then refluxed. The reaction was maintained at this temperature for 2 h. The mixture was then cooled to 0 °C to precipitate a solid. The precipitate was filtered and washed three times with cold ethanol to obtain the target product.

[0071] Example 6: Preparation of Schiff base photoswitching materials

[0072] The specific synthesis steps of the Schiff base provided by this invention are as follows:

[0073] 1.56 g of 4-chlorosalicylaldehyde, 1.79 g of 1-methyl-3-phenylpropanamine, and 5 mL of ethanol were added sequentially to a flask. The mixture was stirred and heated to 80 °C and refluxed. The reaction was maintained at this temperature for 2 h. The mixture was then cooled to 0 °C to precipitate a solid. The precipitate was filtered and washed three times with cold ethanol to obtain the target product.

[0074] Example 7: Preparation of photochromic materials

[0075] The specific preparation steps of the Schiff base photo-switching epoxy resin provided by this invention are as follows:

[0076] Epoxy resin A and B are mixed evenly at a mass ratio of 3:1 and set aside. 3.0 mg of the target product from Example 1 is weighed and dissolved in 1 mL of dichloromethane to prepare a solution. This solution is then poured into 30 g of epoxy resin liquid, mixed evenly, and poured into a mold. The mixture is cured at room temperature for 24 hours. After demolding, Schiff base photo-switching epoxy resin is obtained.

[0077] Example 8: Preparation of photochromic materials

[0078] The specific preparation steps of the Schiff base photo-switching epoxy resin provided by this invention are as follows:

[0079] Epoxy resin A and B are mixed evenly at a mass ratio of 3:1 and set aside. 5.0 mg of the target product from Example 2 is weighed and dissolved in 1 mL of dichloromethane to prepare a solution. This solution is then poured into 30 g of epoxy resin liquid, mixed evenly, and poured into a mold. The mixture is cured at room temperature for 24 hours. After demolding, Schiff base photo-switching epoxy resin is obtained.

[0080] Example 9: Preparation of photochromic materials

[0081] The specific preparation steps of the Schiff base photo-switching epoxy resin provided by this invention are as follows:

[0082] Epoxy resin A and B are mixed evenly at a mass ratio of 3:1 and set aside. 5.0 mg of the target product from Example 3 is weighed and dissolved in 1 mL of dichloromethane to prepare a solution. This solution is then poured into 30 g of epoxy resin liquid, mixed evenly, and poured into a mold. The mixture is cured at room temperature for 24 hours. After demolding, Schiff base photo-switching epoxy resin is obtained.

[0083] Example 10: Preparation of photochromic materials

[0084] The specific preparation steps of the Schiff base photo-switching epoxy resin provided by this invention are as follows:

[0085] Epoxy resin A and B are mixed evenly at a mass ratio of 3:1 and set aside. 1.5 mg of the target product from Example 4 is weighed and dissolved in 1 mL of dichloromethane to prepare a solution. This solution is then poured into 15 g of epoxy resin liquid, mixed evenly, and poured into a mold. The mixture is cured at room temperature for 24 hours. After demolding, Schiff base photo-switching epoxy resin is obtained.

[0086] Example 11: Preparation of photochromic materials

[0087] The specific preparation steps of the Schiff base photo-switching epoxy resin provided by this invention are as follows:

[0088] Epoxy resin A and B are mixed evenly at a mass ratio of 3:1 and set aside. 5.0 mg of the target product from Example 5 is weighed and dissolved in 1 mL of dichloromethane to prepare a solution. This solution is then poured into 42 g of epoxy resin liquid, mixed evenly, and poured into a mold. The mixture is cured at room temperature for 24 hours. After demolding, Schiff base photo-switching epoxy resin is obtained.

[0089] Example 12: Preparation of photochromic materials

[0090] The specific preparation steps of the Schiff base photo-switching epoxy resin provided by this invention are as follows:

[0091] Epoxy resin A and B are mixed evenly at a mass ratio of 3:1 and set aside. 6 mg of the target product from Example 6 is weighed and dissolved in 1 mL of dichloromethane to prepare a solution. This solution is then poured into 30 g of epoxy resin liquid, mixed evenly, and poured into a mold. The mixture is cured at room temperature for 24 hours. After demolding, Schiff base photo-switching epoxy resin is obtained.

[0092] Example 13: Demonstration of the light-changing effect of photochromic materials

[0093] Using the epoxy resin cured product prepared in Example 8 as the display medium, according to Figure 2 The absorption spectrum shown uses a 405nm laser (100mW) as the photochromic light source and a 450nm laser (100mW) as the fluorescence excitation source, with the two light sources intersecting within the display medium. For example... Figure 4As shown, significant fluorescence emission was generated at the intersection of the two light sources inside the display medium, meaning that voxel dots could be generated inside the epoxy resin cured material prepared in Example 8.

[0094] Example 14: Demonstration of the light-changing effect of photochromic materials

[0095] Using the epoxy resin cured product prepared in Example 8 as the display medium, according to Figure 2 The absorption spectrum shown uses a 405nm laser (100mW) as the photochromic light source and a 488nm laser (200mW) as the fluorescence excitation source, with the two light sources intersecting within the display medium. For example... Figure 5 As shown, a 488nm laser forms a screen in the display medium, and a 405nm laser draws a pentagram shape on the screen, realizing a demonstration of a two-dimensional pentagram graphic in space inside the display material.

[0096] This invention uses 4-halosalicylaldehyde and primary amine as raw materials to prepare Schiff base photo-switching materials. Due to the p-π conjugation of halogen atoms with the benzene ring, the electron cloud density at the para position of the halogen atom is slightly higher than that at the meta position, making it easier for the Schiff base to undergo enol-keto configuration conversion, thus improving the luminous efficiency of the material. Taking 4-chlorosalicylaldehyde acetal 1-methyl-3-phenylpropylamine Schiff base as an example, under the co-excitation of a 200mW 405nm laser and a 10mW 488nm laser, the luminous brightness of the epoxy resin cured product of 4-chlorosalicylaldehyde acetal 1-methyl-3-phenylpropylamine Schiff base in Example 12 was measured by a luminometer to be about 60% higher than that of salicylaldehyde acetal 1-methyl-3-phenylpropylamine Schiff base under the same curing conditions.

[0097] Meanwhile, using a continuous shooting mode, the voxel generation and recovery times of the epoxy resin cured product of 4-chlorosalicylic acid 1-methyl-3-phenylpropylamine Schiff base were both measured to be approximately 2 seconds, while the voxel generation time of salicylaldehyde 1-methyl-3-phenylpropylamine Schiff base was approximately 1 minute and the recovery time was approximately 2 minutes. Furthermore, experimental testing revealed that the aggregation-induced fluorescence quenching concentration of the dichloromethane solution of 4-chlorosalicylic acid 1-phenylethylamine Schiff base prepared in Example 4, when excited by 365 nm UV light, was approximately 5 mg / ml, and the aggregation-induced fluorescence quenching concentration of 4-chlorosalicylic acid aniline Schiff base was approximately 1 mg / ml. The increased switching speed and reduced concentration quenching observed above are attributed not only to the electron-withdrawing ability of the 4-halogen substituent but also to the fact that the amino group in the primary amine is not directly connected to the benzene ring, avoiding conjugation of the C=N bond with the benzene ring on the primary amine side, thus increasing the switching speed and reducing the occurrence of aggregation-induced fluorescence quenching in the material molecules.

[0098] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0099] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A Schiff base photo-switching material, characterized in that, It is a compound with the general chemical structural formula (1-4): Equation (1-4) In equation (1-4), X is selected from F, Cl, or Br.

2. The method for preparing the Schiff base photoswitching material according to claim 1, characterized in that, Includes the following steps: 4-Halosalicylaldehyde, primary amine, and organic solvent 1 were added sequentially to a reaction flask, stirred and heated to 78-90℃ and refluxed. After the reaction was fully carried out under the temperature, the mixture was cooled, allowed to crystallize, filtered, washed, and dried to obtain the target product.

3. The preparation method according to claim 2, characterized in that, The primary amine is α-methylbenzylamine; The organic solvent 1 is selected from methanol, ethanol, tetrahydrofuran, 1,4-dioxane, and toluene; The ratio of raw materials used is: 4-halosalicylaldehyde : primary amine = 1 mol : (1.0~1.2) mol, 4-halosalicylaldehyde : organic solvent 1 = 1 g : (3~5) mL; The reaction time is 2-4 hours.

4. A photochromic material, characterized in that, It is obtained by mixing and curing the Schiff base photoswitching material described in claim 1 with epoxy resin; the mass ratio of the Schiff base photoswitching material to epoxy resin is 1: (5000~10000).

5. The method for preparing the photochromic material according to claim 4, characterized in that, Includes the following steps: Weigh out the Schiff base photo-switching material and dissolve it in organic solvent 2 to prepare a solution. Pour the solution into the epoxy resin liquid, mix it evenly, pour the reaction solution into the mold, and after curing and demolding, the product is obtained. The organic solvent 2 is selected from dichloromethane, cyclohexane, tetrahydrofuran, and n-hexane; the Schiff base photoswitching material is prepared with organic solvent 2 in a solution of 0.001~10 mg / mL.

6. The preparation method according to claim 5, characterized in that, The epoxy resin adhesive is obtained by mixing epoxy resin A and epoxy resin B in a mass ratio of 1 to 10:

1. The epoxy resin A is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin and hydrogenated bisphenol A epoxy resin; The epoxy resin B adhesive is an acid anhydride-based resin curing agent.

7. The preparation method according to claim 6, characterized in that, The epoxy resin A and epoxy resin B are mixed in a mass ratio of 3:1; and / or The epoxy resin B is at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, and hexahydrophthalic anhydride; and / or The reaction solution is cured at room temperature for 20-30 hours.

8. The application of the Schiff base photo-switching material of claim 1 or the photochromic material of claim 4 in the preparation of bulk three-dimensional display materials.

9. The application according to claim 8, characterized in that, The volumetric three-dimensional display material is irradiated with an isomer excitation light source and a color-changing excitation light source, and a photon dot is formed at the intersection of the isomer excitation light source and the color-changing excitation light source; By controlling the scanning path and scanning speed of the isomer excitation source and the color-changing excitation source, three-dimensional imaging can be achieved in the material.

10. The application according to claim 9, characterized in that, The isomer excitation source is ultraviolet light; the color-changing excitation source is blue visible light.

11. The application according to claim 10, characterized in that, The wavelength of the ultraviolet light is 350nm to 420nm, and the wavelength of the blue visible light is 450nm to 500nm; The volumetric three-dimensional display material is irradiated with ultraviolet light and blue visible light. The ultraviolet light and blue visible light converge within the material, forming yellow light voxel dots at the convergence point. By controlling the scanning path and scanning speed of the ultraviolet light and blue visible light, a yellow fluorescent three-dimensional image is formed in the material.

Images