Schiff base and preparation method thereof, Schiff base optical switch and preparation method thereof, and optical element

Abstract

The invention provides a Schiff base. The chemical structural formula of the Schiff base is # imgabs0 #. The invention further provides a preparation method of the Schiff base, a Schiff base optical switch applying the Schiff base, a preparation method of the Schiff base optical switch and an optical element applying the Schiff base optical switch.

Description

Technical Field

[0001] The present application relates to a Schiff base, a preparation method of the Schiff base, a Schiff base optical switch containing the Schiff base and a preparation method thereof, and an optical element applying the Schiff base optical switch. Background Art

[0002] A photo-responsive functional material with reversibility can reversibly transform between two isomers under the irradiation of two different wavelengths of light. During the transformation process, the properties of molecules such as the absorption spectrum, emission spectrum, electronic conductivity, electrochemical properties, magnetic properties, coordination properties, dipole-dipole interaction, refractive index, dielectric constant, and geometric structure of the two isomers will be different. Therefore, the photo-responsive functional material can be adjusted by light and thus applied in material fields such as molecular data storage and logic gates, optoelectronic functional devices, photocatalysis, and light-controlled self-assembly.

[0003] However, the current photo-responsive functional materials perform poorly when applied to the field of volumetric three-dimensional display. Among them, in the field of inorganic materials, it has been found that rare-earth-doped fluoride glass can achieve volumetric three-dimensional display, but it is difficult to significantly increase the size of this solid medium and it cannot meet the requirements of volumetric three-dimensional display at the screen level. In the field of organic materials, organic photochromic materials with reversible properties are promising as media for volumetric three-dimensional display, but the slow response speed is the biggest obstacle for most organic photochromic materials to be applied in the field of volumetric three-dimensional display. Summary of the Invention

[0004] The first aspect of the present application provides a Schiff base, and the chemical structural formula of the Schiff base is:

[0005]

[0006] In one embodiment, the absorption spectrum of the Schiff base is 300 nm - 480 nm.

[0007] In one embodiment, the Schiff base is converted from an initial state to an isomer under the irradiation of a first excitation light, and the isomer spontaneously or after being stimulated by visible light returns to the initial state; the isomer generates stimulated light under the irradiation of a second excitation light. The first excitation light is ultraviolet light in the range of 300 nm - 410 nm, and the power range is 10 mW - 200 mW; the second excitation light is blue light in the range of 440 nm - 480 nm, and the power range is 5 mW - 100 mW.

[0008] In one embodiment, the response time of the Schiff base to generate the stimulated light under the simultaneous irradiation of the first excitation light and the second excitation light is less than 1 second.

[0009] In one embodiment, the change in the chemical structural formula of the Schiff base under the irradiation of the first excitation light is as follows:

[0010]

[0011] The Schiff base provided by the embodiments of the present application can emit yellow fluorescence under the co-excitation of ultraviolet light and blue light, and can return to the initial state spontaneously or after being stimulated by visible light, with a fast response speed, which is beneficial to being used as a fast-response optical switch material.

[0012] The second aspect of the present application provides a method for preparing a Schiff base for preparing the above-mentioned Schiff base, including:

[0013] Mix p-methoxysalicylaldehyde and 2-amino-3-methylpyridine in absolute ethanol;

[0014] Carry out a reflux reaction on the mixture for 2-4 h;

[0015] Cool, filter, and wash the product after the reflux reaction to obtain the Schiff base.

[0016] The method for preparing a Schiff base provided by the embodiments of the present application has low raw material costs and a simple process flow, which is beneficial to industrial application.

[0017] In one embodiment, the molar ratio of p-methoxysalicylaldehyde to 2-amino-3-methylpyridine is 1:0.8-1:1.2, and the molar concentration of p-methoxysalicylaldehyde in the absolute ethanol is 0.05 mol / L-1 mol / L.

[0018] In one embodiment, the step of cooling the product after the reflux reaction is specifically: cooling the product after the reflux reaction to -4°C - 4°C.

[0019] In one embodiment, the steps of cooling, filtering, and washing the product after the reflux reaction specifically include: washing the filtered product with cold ethanol 2-5 times.

[0020] The third aspect of the present application provides a Schiff base optical switch, including:

[0021] The above-mentioned Schiff base; and

[0022] A transparent medium, the Schiff base is mixed in the transparent medium, and the mass ratio of the Schiff base to the transparent medium is 1:5000-1:10000.

[0023] The Schiff base optical switch provided by the embodiments of the present application has high transparency by arranging the Schiff base in the transparent medium, and the stability and reversibility of the Schiff base light response are good, and it can be used as a fast-response optical switch material and applied to fields such as two-dimensional or volumetric three-dimensional display, multiple security anti-counterfeiting, and three-dimensional data storage.

[0024] In one embodiment, the transparent medium includes one of epoxy resin, polymethyl methacrylate or polycarbonate.

[0025] The fourth aspect of the present application provides a preparation method of a Schiff base optical switch for preparing the above-mentioned Schiff base optical switch, including:

[0026] Dissolve the Schiff base in an organic solvent and pour it into the transparent medium solution;

[0027] After mixing the mixed solution evenly, pour it into a mold for curing at room temperature;

[0028] Demold the cured product to obtain the Schiff base optical switch.

[0029] The preparation method of the Schiff base optical switch provided by the embodiment of the present application has low raw material cost and simple process flow, which is beneficial to industrial application.

[0030] In one embodiment, the transparent medium is epoxy resin, the transparent medium solution includes glue A and glue B, and the mass ratio of glue A to glue B is 2.85:1 - 3.15:1.

[0031] In one embodiment, the transparent medium includes one of polymethyl methacrylate or polycarbonate.

[0032] In one embodiment, the organic solvent includes one or several mixtures of dichloromethane, dichloroethane, ethyl acetate, toluene, tetrahydrofuran, N,N-dimethylformamide.

[0033] In one embodiment, the mass concentration of the Schiff base in the organic solvent is 1 g / L - 20 g / L.

[0034] The fifth aspect of the present application provides an optical element, including: the above-mentioned Schiff base optical switch.

[0035] In one embodiment, the optical element is one of a two-dimensional display device, a three-dimensional display device, an optical control switch element or a multiple-light-emitting anti-counterfeiting material. Description of the Drawings

[0036] Figure 1 It is a schematic diagram of the absorption spectrum of the Schiff base in an embodiment of the present application.

[0037] Figure 2 It is the 1H NMR spectrum of the Schiff base in an embodiment of the present application.

[0038] Figure 3 It is the preparation flow chart of the Schiff base in an embodiment of the present application.

[0039] Figure 4The flowchart for the preparation of the Schiff base optical switch in an embodiment of the present application.

[0040] Figure 5 The schematic diagram of the Schiff base optical switch under dual-wavelength light excitation in an embodiment of the present application.

[0041] Description of main component symbols

[0042] Steps S11, S12, S13, S21, S22, S23 The following specific embodiments will further illustrate the present application in conjunction with the above-mentioned drawings. Specific embodiments

[0043] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments.

[0044] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application.

[0045] To further elaborate on the technical means and effects adopted by the present application to achieve the predetermined purpose, the following detailed description of the present application is made in conjunction with the drawings and preferred embodiments.

[0046] The embodiments of the present application provide a Schiff base, and its chemical structural formula is:

[0047]

[0048] The chemical structural formula is the structural formula of the Schiff base in the natural state. Please refer to Figure 1 , It can be seen from the absorption spectrum diagram that the Schiff base provided by the present application has strong absorption in the ultraviolet region of 300 nm - 410 nm, and weak absorption in the region of 410 nm - 480 nm. Therefore, ultraviolet light can be selected as the first excitation light of the Schiff base.

[0049] The Schiff base provided by the present application is converted from the initial state (i.e., the natural state) to an isomer under the irradiation of the first excitation light, and the isomer spontaneously or after being stimulated by visible light returns to the initial state; the isomer can generate stimulated light under the irradiation of the second excitation light. Specifically, the change in the chemical structural formula of the Schiff base under the irradiation of the first excitation light is as follows:

[0050]

[0051] Among them, the first excitation light can be ultraviolet light in the range of 300 nm - 410 nm, and the power range is 10 mW - 200 mW. The second excitation light can be blue light in the range of 440 nm - 480 nm, and the power range is 5 mW - 100 mW. When the first excitation light and the second excitation light are simultaneously irradiated on the Schiff base, the stimulated emission generated by the Schiff base converted into an isomer under the action of the second excitation light is yellow fluorescence. The response time of the Schiff base to generate stimulated emission under the simultaneous irradiation of the first excitation light and the second excitation light is less than 1 second.

[0052] The Schiff base provided by the embodiment of the present application can be converted into an isomer under the irradiation of the first excitation light. The isomer generates stimulated emission under the irradiation of the second excitation light. The overall response speed is fast and it can be applied to various application scenarios. For example, two-dimensional display devices, three-dimensional display devices, light-controlled switch elements, or multiple-emission anti-counterfeiting materials, etc.

[0053] Please refer to Figure 3 , the embodiment of the present application also provides a preparation method of a Schiff base, including:

[0054] Step S11: Mix p-methoxysalicylaldehyde and 2-amino-3-methylpyridine in absolute ethanol;

[0055] Step S12: Carry out a reflux reaction on the mixture for 2 - 4 h;

[0056] Step S13: Cool, filter, and wash the product after the reflux reaction to obtain the Schiff base.

[0057] In step S11, the molar ratio of p-methoxysalicylaldehyde to 2-amino-3-methylpyridine is 1:0.8 - 1:1.2, and the molar concentration of p-methoxysalicylaldehyde in absolute ethanol is 0.05 mol / L - 1 mol / L.

[0058] In step S13, it specifically includes:

[0059] Step S131: Cool the mixed solution after the reflux reaction to -4°C - 4°C;

[0060] Step S132: Filter the cooled mixed solution to obtain a crude product;

[0061] Step S133: Wash the crude product with cold ethanol 2 - 5 times, and obtain the target product after drying.

[0062] The preparation method of the Schiff base provided by the embodiment of the present application has low raw material cost and simple process flow, which is conducive to industrial application.

[0063] The embodiment of the present application also provides a Schiff base optical switch, which includes the Schiff base in the above embodiment and a transparent medium. Among them, the Schiff base is mixed in the transparent medium, and the mass ratio of the Schiff base to the transparent medium is 1:5000 - 1:10000.

[0064] Specifically, the Schiff base optical switch is prepared by mixing the Schiff base into the transparent medium, so that the light-impermeable Schiff base is dispersed in the transparent medium, forming an approximately transparent effect. That is to say, the transparent medium is the application medium of the Schiff base. The transparent medium can include one of epoxy resin, polymethyl methacrylate or polycarbonate.

[0065] The first excitation light can be used to control the on / off state of the Schiff base optical switch. Specifically, when the first excitation light irradiates the Schiff base optical switch, the Schiff base mixed in the epoxy resin generates isomers under the irradiation of the first excitation light, which is regarded as the "on" state. After the first excitation light is withdrawn, the isomers return to the initial state spontaneously or under the stimulation of visible light, which is regarded as the "off" state.

[0066] The "on" or "off" state of the Schiff base optical switch can be confirmed by the second excitation light. Please refer to Figure 5 , when the first excitation light and the second excitation light irradiate the Schiff base optical switch and converge at one place respectively, stimulated emission is generated at the intersection of the first excitation light and the second excitation light. That is to say, the area where stimulated emission is generated after the Schiff base optical switch is irradiated by the second excitation light can be judged as the "on" state, and the area where no stimulated emission is generated can be judged as the "off" state.

[0067] By setting the first excitation light and the second excitation light, stimulated emission can be generated at a specified position in the Schiff base optical switch, and thus two-dimensional or volumetric three-dimensional display can be realized in the Schiff base optical switch. That is to say, the Schiff base optical switch can be used as the display medium of a two-dimensional or three-dimensional display device. The Schiff base optical switch can also be used to manufacture an optical control switch element or a multi-luminescent anti-counterfeiting material.

[0068] The Schiff base optical switch provided by the embodiment of the present application can obtain an approximately transparent Schiff base optical switch by mixing the Schiff base with the transparent medium, so that the first excitation light and the second excitation light can converge at any position of the Schiff base optical switch, and stimulated emission is generated at the corresponding position of the Schiff base optical switch, thereby improving the application scope of the Schiff base material and enabling the Schiff base optical switch to be applied to a variety of application scenarios. For example, two-dimensional display devices, three-dimensional display devices, optical control switch elements or multi-luminescent anti-counterfeiting materials, etc.

[0069] Please refer to Figure 4 , the embodiment of the present application also provides a preparation method of the above Schiff base optical switch, including:

[0070] Step S21: Dissolve the Schiff base in an organic solvent and pour it into the transparent medium solution;

[0071] Step S22: Mix the mixed solution evenly and pour it into a mold for curing at room temperature;

[0072] Step S23: Demold the cured product to obtain the Schiff base optical switch.

[0073] In step S21, the organic solvent is a good solvent for the Schiff base, and specifically may include one or several mixtures of dichloromethane, dichloroethane, ethyl acetate, toluene, tetrahydrofuran, N, N-dimethylformamide. The mass concentration of the Schiff base in the organic solvent is 1 g / L - 20 g / L.

[0074] In this embodiment, the transparent medium can be epoxy resin, and the transparent medium solution includes glue A and glue B, and the mass ratio of glue A to glue B is 2.85:1 - 3.15:1. Specifically, the transparent medium solution is a room temperature curing two-component epoxy resin glue, including glue A and glue B. Among them, glue A can specifically be bisphenol A type epoxy resin, and glue B can specifically be a polyamine curing agent. The curing temperature of the transparent medium solution is 5°C - 40°C, and the curing time is 10 h - 30 h. The mass ratio of the Schiff base to the transparent medium solution is 1:5000 - 1:10000. In other embodiments, the transparent medium can also be one of polymethyl methacrylate or polycarbonate.

[0075] Step S22 specifically includes: After stirring the Schiff base dissolved in the organic solvent and the epoxy resin solution evenly, evacuate and remove bubbles for 5 - 20 minutes, pour it into a mold, and cure it at a temperature of 5°C - 40°C for 10 h - 30 h.

[0076] The method for preparing the Schiff base optical switch provided by the embodiment of the present application has low raw material cost and simple process flow, which is beneficial to industrial application.

[0077] The embodiment of the present application also provides an optical element, including the Schiff base optical switch in the above embodiment. The optical element can be one of a two-dimensional display device, a three-dimensional display device, an optical control switch element, or a multi-emission anti-counterfeiting material.

[0078] Specifically, the Schiff base optical switch can be used as a display medium for two-dimensional or three-dimensional display devices. Since the Schiff base optical switch is an epoxy resin mixed with Schiff base, it is approximately transparent as a whole. And when the Schiff base is irradiated by the first excitation light and the second excitation light simultaneously, it will generate yellow stimulated emission. Therefore, by setting the first excitation light and the second excitation light, stimulated emission can be generated at any position of the Schiff base optical switch. By controlling the beam cross-sectional sizes of the first excitation light and the second excitation light, the size of a single region where stimulated emission is generated can be controlled. The smallest region where stimulated emission is generated can be set as a pixel. By setting multiple beams of the first excitation light and multiple beams of the second excitation light, multiple luminous pixels can be generated within the Schiff base optical switch. By setting the spatial positions of multiple pixels, two-dimensional or three-dimensional display can be realized accordingly.

[0079] Since the Schiff base can be converted into an isomer under the irradiation of the first excitation light of ultraviolet light and generate yellow stimulated emission under the irradiation of the second excitation light, the Schiff base optical switch can also be used to prepare an optically controlled switch element.

[0080] Since the Schiff base can generate yellow stimulated emission under the co-irradiation of the first excitation light and the second excitation light, the Schiff base optical switch can be used to prepare a multi-luminescence anti-counterfeiting material. That is, the object to be detected can be irradiated with the first excitation light and the second excitation light simultaneously, and the authenticity of the object to be detected can be judged according to whether yellow fluorescence is generated.

[0081] The embodiments of the present application will be further described below through specific examples.

[0082] Example 1

[0083] 1.52 g of p-methoxysalicylaldehyde and 1.08 g of 2-amino-3-methylpyridine were mixed in 50 mL of absolute ethanol, and refluxed for 4 h. After cooling to 0 °C, the precipitate was filtered, and washed 3 times with cold ethanol to obtain the Schiff base.

[0084] Figure 2 For the nuclear magnetic resonance hydrogen spectrum of the Schiff base obtained in Example 1, it can be determined from the positions (chemical shifts) of the peaks corresponding to the hydrogen atoms and the areas of the peaks (number of hydrogen atoms) in Figure 2 that the product prepared in Example 1 corresponds to the molecular structural formula of the Schiff base, verifying that the Schiff base with this molecular structural formula has been formed.

[0085] Example 2

[0086] 0.51 g of p-methoxysalicylaldehyde and 0.39 g of 2-amino-3-methylpyridine were mixed in 20 mL of absolute ethanol, and refluxed for 2 h. After cooling to 0 °C, the precipitate was filtered, and washed 3 times with cold ethanol to obtain the Schiff base.

[0087] Example 3

[0088] Weigh 3.2 mg of the Schiff base synthesized in Example 1 and dissolve it in 1 mL of dichloromethane solution. Mix it with 15 g of epoxy resin A glue and 5 g of epoxy resin B glue. After stirring evenly, evacuate and remove bubbles for 10 min, pour it into a mold, and cure it at 25 °C for 24 h. After demolding, the Schiff base optical switch can be obtained.

[0089] Select 10 mW, 405 nm ultraviolet light as the first excitation light source, and select 40 mW, 450 nm blue light as the second excitation light source. The two light sources intersect in the Schiff base optical switch. Use a camera to continuously record the switching speed of the Schiff base under a 510 nm filter. The results show that within 1 second after turning on the light source, a luminescent voxel point can be observed at the intersection of the light sources, as Figure 5 shown. Turn off the ultraviolet light without turning off the blue light, and the voxel point disappears after 3 seconds. It shows that the Schiff base provided by this application can complete a switching cycle within 4 seconds.

[0090] Example 4

[0091] Similar to Example 3, only replace the Schiff base synthesized in Example 1 with the Schiff base synthesized in the example. The obtained Schiff base optical switch can also complete a switching cycle within 4 seconds.

[0092] Comparative Example 1

[0093] Obtain spiropyran SP-5-An-9 according to the preparation method in the literature "Pressure induced the largest emission wavelength change in asingle crystal". Spiropyran SP-5-An-9 is a reversibly photochromic material reported in the literature, and its structural formula is as follows:

[0094]

[0095] Weigh 3.2 mg of spiropyran SP-5-An-9 and dissolve it in 1 mL of dichloromethane solution. Mix it with 15 g of epoxy resin A glue and 5 g of epoxy resin B glue. After stirring evenly, evacuate and remove bubbles for 10 min, pour it into a mold, and cure it at 25 °C for 24 h. After demolding, the spiropyran SP-5-An-9 epoxy resin can be obtained.

[0096] Select 10 mW of 405 nm ultraviolet light as the first excitation light source, and select 40 mW of 480 nm blue light as the second excitation light source. The two light sources are simultaneously irradiated onto the spiropyran SP-5-An-9 epoxy resin prepared in Comparative Example 1. Continuously photograph with a camera to record the switching speed of spiropyran SP-5-An-9. The results show that within 1 second after turning on the light source, a luminescent voxel point can be observed at the intersection of the light sources. Turn off the ultraviolet light without turning off the blue light, and the voxel point disappears after 60 seconds. It shows that spiropyran SP-5-An-9 reported in the literature takes at least 61 seconds to complete one switching cycle, and the switching speed is much lower than that of the Schiff base optical switch provided by the present invention.

[0097] Those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to limit the present application. As long as appropriate changes and variations made to the above embodiments fall within the scope of the spirit of the present application, they fall within the scope of protection required by the present application.

Claims

1. A Schiff base, characterized in that, The chemical structural formula of the Schiff base in its natural state is as follows:

2. The Schiff base according to claim 1, wherein, The absorption spectrum of the Schiff base is 300 nm - 480 nm.

3. The Schiff base according to claim 1, wherein Under the irradiation of the first excitation light, the Schiff base is converted from the chemical structural formula in its natural state into an isomer, and the isomer spontaneously or after being stimulated by visible light returns to the chemical structural formula in its natural state; under the irradiation of the second excitation light, the isomer generates stimulated light. The first excitation light is ultraviolet light in the range of 300 nm - 410 nm, and the power range is 10 mW - 200 mW; the second excitation light is blue light in the range of 440 nm - 480 nm, and the power range is 5 mW - 100 mW.

4. The Schiff base according to claim 3, wherein The response time for the Schiff base to generate the stimulated light under the simultaneous irradiation of the first excitation light and the second excitation light is less than 1 second.

5. The Schiff base according to claim 3, wherein The change in the chemical structural formula of the Schiff base under the irradiation of the first excitation light is as follows:

6. A method for preparing Schiff base, which is used to prepare the Schiff base described in any one of claims 1-5, characterized in that, Including: Mix p-methoxysalicylaldehyde and 2-amino-3-methylpyridine in absolute ethanol to obtain a mixture; Carry out a reflux reaction on the mixture for 2 - 4 h; Cool, filter, and wash the product after the reflux reaction to obtain the Schiff base.

7. The preparation method of the Schiff base according to claim 6, characterized in that, The molar ratio of p-methoxysalicylaldehyde to 2-amino-3-methylpyridine is 1:0.8 - 1:1.2, and the molar concentration of p-methoxysalicylaldehyde in the absolute ethanol is 0.05 mol / L - 1 mol / L.

8. The preparation method of the Schiff base according to claim 6, characterized in that, The step of cooling the product after the reflux reaction is specifically: cooling the product after the reflux reaction to -4°C to 4°C.

9. The preparation method of the Schiff base according to claim 6, wherein, The steps of cooling, filtering, and washing the product after the reflux reaction specifically include: washing the filtered product with cold ethanol 2 - 5 times.

10. A Schiff base optical switch, characterized in that, Including: The Schiff base according to any one of claims 1 - 5; And A transparent medium, the Schiff base is mixed in the transparent medium, and the mass ratio of the Schiff base to the transparent medium is 1:5000 - 1:10000.

11. The Schiff base optical switch according to claim 10, wherein, The transparent medium includes one of epoxy resin, polymethyl methacrylate, or polycarbonate.

12. A preparation method of a Schiff base optical switch, characterized in that, Including: Dissolve the Schiff base in an organic solvent and then pour it into the transparent medium solution, where the Schiff base is the Schiff base according to any one of claims 1 - 5; Mix the mixed solution evenly and then pour it into a mold for room temperature curing; Demold the cured product to obtain the Schiff base optical switch.

13. The preparation method of the Schiff base optical switch according to claim 12, characterized in that, The transparent medium is epoxy resin, the transparent medium solution includes A glue and B glue, and the mass ratio of A glue to B glue is 2.85:1 - 3.15:

1.

14. The preparation method of the Schiff base optical switch according to claim 12, characterized in that, The transparent medium includes one of polymethyl methacrylate or polycarbonate.

15. The preparation method of the Schiff base optical switch according to claim 12, wherein, The organic solvent includes one or a mixture of dichloromethane, dichloroethane, ethyl acetate, toluene, tetrahydrofuran, N,N-dimethylformamide.

16. The preparation method of the Schiff base optical switch according to claim 12, characterized in that, The mass concentration of the Schiff base in the organic solvent is 1 g / L - 20 g / L.

17. An optical element, characterized in that, Including: A Schiff base optical switch, where the Schiff base is the Schiff base according to any one of claims 1 - 5.

18. The optical element according to claim 17, wherein The optical element is one of a two-dimensional display device, a three-dimensional display device, an optical control switch element, or a multi-emission anti-counterfeiting material.

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