Preparation method and anti-counterfeiting application of metal organic framework heterojunction based on charge transfer in differentiated ligands

Abstract

The invention discloses a preparation method of a metal organic framework heterojunction based on charge transfer in differentiated ligands and an anti-counterfeiting application of the metal organic framework heterojunction. A metal organic framework is prepared from an organic ligand A, an organic ligand TCPE, zinc nitrate and the like through a solvothermal method, the triblock metal organic framework heterojunction is prepared from a mixed solution of an organic ligand B, an organic ligand TCPE, zinc nitrate and the like and the metal organic framework, the organic ligand A is any one of DPBD, DPA and DPB, the organic ligand B is DPA or DPB, and the organic ligand A and the organic ligand B are different from each other. The metal organic framework heterojunction is a rod-shaped composite material which is formed by two different metal organic frameworks through chemical bonding, physical stacking and the like and is provided with a heterojunction interface, and can be used for designing a stable photon bar code as an anti-counterfeit label. The triblock metal organic framework heterostructure realizes a modulatable and steady stimuli-responsive fluorescence signal, and can be used for coding and decoding anti-counterfeiting photon barcodes and high-grade anti-counterfeiting of artworks.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescent metal organic framework heterojunctions, and specifically relates to a preparation method of a metal organic framework heterojunction based on differentiated intra-ligand charge transfer and its anti-counterfeiting application. Background Art

[0002] Metal-organic frameworks (MOFs) with unique dynamics and multifunctional modules play a pivotal role in different research fields. Luminescent MOFs utilize the optoelectronic properties of metal centers and organic ligands and the infinite combination of optical mechanisms to achieve various responsive luminescence properties under chemical / physical stimulation, providing great potential for information encryption and advanced anti-counterfeiting technologies. Typically, responsive MOFs always rely on a single framework, with problems of limited emission control and low information complexity, and face great challenges in meeting the escalating requirements of advanced anti-counterfeiting technologies for multiple authentication and information security. In contrast, MOF heterostructures integrate different responsive frameworks into a unified system, which is not only conducive to the harmonious coexistence of different stimulus-responsive behaviors, but also has recognizable colors and independent emission regions, which is conducive to the generation of dynamic multi-color synergistic signals. It is a promising high-security anti-counterfeiting platform. However, the construction of multicolor responsive MOF heterostructures remains a huge challenge due to the following obstacles: (1) Traditional responsive heterostructure design relies heavily on differentiated metal nodes, which always require harsh stimulation conditions (such as high temperature, high pressure, acid and alkali) to trigger responsive behavior, which makes MOF heterostructures suffer from poor reversibility and low crystallinity. (2) Organic ligands with different optical response properties always have different molecular configurations, resulting in poor compatibility and low lattice matching, which limits the formation of stable MOF heterostructures. Therefore, a milder stimulation condition is needed to trigger fluorescent MOF heterojunctions and explore their preparation methods and applications in anti-counterfeiting photonic barcodes. Summary of the invention

[0003] In order to address the deficiencies of the prior art, the present invention provides a preparation method of a metal-organic framework heterojunction based on differentiated intra-ligand charge transfer and its anti-counterfeiting application, specifically involving a preparation method of three metal-organic frameworks and three triblock metal-organic framework heterostructures and the application of their differentiated and switchable stimulus response signals in robust anti-counterfeiting photonic barcodes.

[0004] The luminescent organic ligands in metal-organic frameworks are composed of coordination groups and aromatic skeletons. The electron-donating aromatic skeletons can easily redistribute charge with the electron-accepting coordination groups, thereby inducing intra-ligand charge transfer that is sensitive to the surrounding environment and is conducive to responding under mild stimulation. Therefore, adjusting the electron-donating ability of the aromatic skeleton while keeping the coordination groups unchanged may create optical ligands with both differentiated intra-ligand charge transfer and similar coordination modes, which is conducive to the construction of metal-organic framework heterostructures with multicolor responses.

[0005] Designing the same type of electron-donating groups in the aromatic backbone of a MOF facilitates the emergence of highly similar ligand conformations and helps achieve lattice matching, thereby integrating different MOFs into a single heterostructure. Adjusting the number and substitution positions of electron-donating groups in the aromatic backbone can induce different strengths of intra-ligand charge transfer, so that the MOF exhibits different intrinsic emissions, making it possible to achieve multicolor emission in MOF heterostructures. Finally, different electron-donating groups on the aromatic backbone can produce bonding effects with surrounding molecules, which then leads to different confinements of charge-transfer ligands. Under the same mild stimulus, this will endow different regions of the MOF with different reaction behaviors, which is conducive to the construction of robust responsive MOF heterosystems.

[0006] Based on the above ideas, the present invention adopts the following technical solutions:

[0007] A method for preparing a metal organic framework heterojunction based on differentiated intra-ligand charge transfer comprises the following steps:

[0008] 1) dissolving organic ligand A, organic ligand TCPE and metal zinc nitrate in an organic solvent DMF at a molar ratio of 1:2:5; adding poor solvent water and hydrochloric acid solution to the uniformly mixed solution, and ultrasonicating to obtain a mixed solution; putting the mixed solution into a glass bottle, placing it in an oven for heating, then taking it out and cooling it to room temperature, and washing it with an organic solvent DMF for 3 to 4 times to obtain a rod-shaped metal organic framework with regular morphology and smooth surface;

[0009] 2) dissolving the organic ligand B, the organic ligand TCPE and the metal zinc nitrate in an organic solvent DMF at a molar ratio of 1:2:5; adding poor solvent water and hydrochloric acid solution to the uniformly mixed solution, ultrasonicating to obtain a mixed solution, placing the mixed solution and the metal organic framework prepared in step 1) into a glass bottle and heating it in an oven, then taking it out and cooling it to room temperature, washing it with an organic solvent DMF for 3 to 4 times, and obtaining a triblock metal organic framework heterojunction with a regular morphology and a smooth surface;

[0010] The organic ligand A is any one of DPBD, DPA and DPB, the organic ligand B is DPA or DPB, and the organic ligand A and the organic ligand B are different from each other;

[0011] Among them, DPBD is 3,6-dipyridine-4-tetraphenyl-1,2-diamine, DPA is 2,5-dipyridine-4-acylanilide, DPB is 1,4-dipyridine-4-alkylbenzene, TCPE is tetracarboxytetraphenylethylene, and the structural formulas are as follows:

[0012]

[0013] Furthermore, in step 1), the total amount ratio of the organic ligand A, the organic ligand TCPE, and the metal zinc nitrate to the organic solvent DMF is 8 mmol: 2-2.2 ml.

[0014] Furthermore, in step 1), the total amount of the organic ligand A, the organic ligand TCPE, the metal zinc nitrate, the water, and the hydrochloric acid is in a ratio of 8 mmol:1-1.1:ml:300-320 μL.

[0015] Furthermore, in step 2), the total amount ratio of the organic ligand B, the organic ligand TCPE, and the metal zinc nitrate to the organic solvent DMF is 8 mmol: 2 to 2.2 ml.

[0016] Furthermore, in step 2), the total amount of the organic ligand B, the organic ligand TCPE, the metal zinc nitrate, water, and the hydrochloric acid is in a ratio of 8 mmol:1-1.1:ml:300-320 μL.

[0017] Furthermore, the ultrasonic time in step 1) and step 2) is 4.5 to 5.5 min, and the ultrasonic frequency is 55 to 65 kHz.

[0018] Furthermore, the heating temperature of the oven in step 1) and step 2) is 60 ～ 100°C, heating time is 24 to 48 hours, preferably heating at 80°C for 24 hours.

[0019] As an embodiment of the present invention, the organic ligand A is DPBD, and the organic ligand B is DPA.

[0020] As an embodiment of the present invention, the organic ligand A is DPBD, and the organic ligand B is DPB.

[0021] As an embodiment of the present invention, the organic ligand A is DPA, and the organic ligand B is DPB.

[0022] In the present invention, the organic solvent DMF (N,N-dimethylformamide) is a good solvent for the organic ligands DPBD, DPA, DPB and TCPE, and water is a poor solvent for the organic ligands DPBD, DPA, DPB and TCPE.

[0023] The invention uses an organic solvent DMF to wash the organic molecules remaining on the surface of the rod-shaped metal organic framework to obtain high-quality metal organic framework heterostructure seeds.

[0024] The organic solvent DMF can also be replaced by other organic solvents, such as DMA (dimethylacetamide) and the like.

[0025] The triblock metal organic framework heterojunction of the present invention is synthesized by a simple solvothermal method. It is a rod-shaped composite material with a heterojunction interface formed by two different metal organic frameworks through specific chemical bonding, physical stacking, etc., and can be used to design robust photonic barcodes as anti-counterfeiting labels. The triblock metal organic framework heterostructure realizes a modulatable robust stimulus response fluorescence signal, which can be used for encoding and decoding of anti-counterfeiting photonic barcodes and advanced anti-counterfeiting of artworks.

[0026] Beneficial effects of the present invention:

[0027] 1. The metal-organic framework heterostructures of the present invention have smooth surfaces and easily distinguishable emission regions; similar metal-organic frameworks designed with differentiated intra-ligand charge transfer are integrated through time-dependent epitaxial growth to form multi-color metal-organic framework heterostructures. Different numbers of electron-donating groups in the metal-organic framework blocks have different spatial regulation of the torsion of the charge transfer ligands, triggering different response emissions under the same mild stimulation, thereby generating a variety of adjustable color patterns in the heterostructures. These spatially resolved metal-organic framework heterostructures with stable multi-color response patterns enable the encoding of fingerprint information, further serving as robust anti-counterfeiting labels with high-security conversion states. These results provide a new solution to the compatibility problem of different photoresponses with low lattice matching, and provide a promising path for the advanced information development of metal-organic framework heterosystems with smart responses.

[0028] 2. The present invention provides a method for preparing a metal organic framework and a metal organic framework heterojunction. The preparation method is simple and easy to operate. The metal organic framework and the metal organic framework heterojunction synthesized by the solvothermal method have a smooth surface and good stability, which is conducive to achieving robust fluorescence stimulus response regulation under mild stimulation conditions.

[0029] 3. The present invention provides an application of a metal-organic framework heterojunction, whose highly stable, switchable fluorescence stimulus response allows the design of robust anti-counterfeiting labels with high-security conversion states. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Fluorescence images of three metal organic frameworks FJU-666, FJU-667 and FJU-668. The scale bar of the fluorescence image is 50 μm.

[0031] Figure 2 The crystal structures of three metal-organic frameworks FJU-666, FJU-667 and FJU-668.

[0032] Figure 3 Fluorescence images of the metal-organic framework heterostructure MH-1 at different growth stages. The scale bar of the fluorescence image is 50 μm.

[0033] Figure 4 , A is a fluorescence image of the metal organic framework heterostructure MH-1, and B is a scanning electron microscope image of the metal organic framework heterostructure MH-1. The size of A and B is 20 μm.

[0034] Figure 5 Fluorescence images of metal-organic framework heterostructures MH-2 and MH-3. The scale bar of the fluorescence image is 50 μm.

[0035] Figure 6 This is the fluorescence image of the metal-organic framework heterostructures MH-1, MH-2 and MH-3 under the stimulation and volatilization of dichloromethane.

[0036] Figure 7 The PL spectra of metal-organic framework heterostructures MH-1, MH-2 and MH-3 were obtained and robust anti-counterfeiting labels with high-security switching states were designed using PL spectra for encoding.

[0037] Figure 8 Demonstration of photonic barcode based on metal-organic framework heterostructure for anti-counterfeiting of artworks. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content recorded in the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the present invention equally.

[0039] Example 1

[0040] Preparation method of metal organic framework FJU-666

[0041] The ligand DPBD (0.01mmol), TCPE (0.02mmol) and metal zinc nitrate (0.05mmol) were uniformly dissolved in the organic solvent DMF (2ml); poor solvent water (1ml) and hydrochloric acid solution (300μL) were added to the uniformly mixed solution and ultrasonicated to obtain a mixed solution; the mixed solution was placed in a glass bottle and heated in an oven at 80℃ for 24h; the mixture was taken out and cooled to room temperature, and washed three times with DMF to obtain a rod-shaped metal organic framework FJU-666 with regular morphology and smooth surface.

[0042] Example 2

[0043] Preparation method of metal organic framework FJU-667

[0044] The ligand DPA (0.01mmol), TCPE (0.02mmol) and metal zinc nitrate (0.05mmol) were uniformly dissolved in the organic solvent DMF (2ml); poor solvent water (1ml) and hydrochloric acid solution (300μL) were added to the uniformly mixed solution and ultrasonicated to obtain a mixed solution; the mixed solution was placed in a glass bottle and heated in an oven at 80℃ for 24h; the mixture was taken out and cooled to room temperature, and washed three times with DMF to obtain a rod-shaped metal organic framework FJU-667 with regular morphology and smooth surface.

[0045] Example 3

[0046] Preparation method of metal organic framework FJU-668

[0047] First, the ligands DPB, TCPE and metal zinc nitrate are uniformly dissolved in an organic solvent in a ratio of 1:2:5; poor solvent water is added to the uniformly mixed solution and ultrasonicated; the mixed solution is placed in a glass bottle and heated in an oven; the mixture is taken out and cooled to room temperature, and washed three times with an organic solvent (DMF) to obtain a rod-shaped metal organic framework FJU-668 with a regular morphology and a smooth surface.

[0048] The ligand DPB (0.01mmol), TCPE (0.02mmol) and metal zinc nitrate (0.05mmol) were uniformly dissolved in the organic solvent DMF (2ml); poor solvent water (1ml) and hydrochloric acid solution (300μL) were added to the uniformly mixed solution and ultrasonicated to obtain a mixed solution; the mixed solution was placed in a glass bottle and heated in an oven at 80℃ for 24h; the mixture was taken out and cooled to room temperature, and washed three times with DMF to obtain a rod-shaped metal organic framework FJU-668 with regular morphology and smooth surface.

[0049] Example 4

[0050] Preparation method of metal organic framework heterostructure MH-1

[0051] 1) Obtain the metal organic framework FJU-666 according to the preparation method of Example 1

[0052] 2) Preparation method of metal organic framework heterostructure MH-1

[0053] The ligand DPA (0.01mmol), TCPE (0.02mmol) and metal zinc nitrate (0.05mmol) were uniformly dissolved in the organic solvent DMF (2ml); poor solvent water (1ml) and hydrochloric acid solution (300μL) were added to the uniformly mixed solution and ultrasonicated to obtain a mixed solution; the mixed solution and the above-mentioned metal organic framework FJU-666 were placed in a glass bottle and placed in an oven at 80℃ for 24h; the bottle was taken out and cooled to room temperature, and washed three times with DMF to obtain a triblock metal organic framework heterojunction MH-1 with regular morphology and smooth surface.

[0054] Example 5

[0055] Preparation method of metal organic framework heterostructure MH-2

[0056] 1) Obtain the metal organic framework FJU-666 according to the preparation method of Example 1

[0057] 2) Preparation method of metal organic framework heterostructure MH-1

[0058] The ligand DPB (0.01mmol), TCPE (0.02mmol) and metal zinc nitrate (0.05mmol) were uniformly dissolved in the organic solvent DMF (2ml); poor solvent water (1ml) and hydrochloric acid solution (300μL) were added to the uniformly mixed solution and ultrasonicated to obtain a mixed solution; the mixed solution and the above-mentioned metal organic framework FJU-666 were placed in a glass bottle and placed in an oven at 80℃ for 24h; the bottle was taken out and cooled to room temperature, and washed three times with DMF to obtain a triblock metal organic framework heterojunction MH-2 with regular morphology and smooth surface.

[0059] Example 6

[0060] Preparation method of metal organic framework heterostructure MH-2

[0061] 1) Obtain the metal organic framework FJU-667 according to the preparation method of Example 2

[0062] The ligand DPB (0.01mmol), TCPE (0.02mmol) and metal zinc nitrate (0.05mmol) were uniformly dissolved in the organic solvent DMF (2ml); poor solvent water (1ml) and hydrochloric acid solution (300μL) were added to the uniformly mixed solution and ultrasonicated to obtain a mixed solution; the mixed solution and the above-mentioned metal organic framework FJU-667 were placed in a glass bottle and placed in an oven at 80℃ for 24h; the bottle was taken out and cooled to room temperature, and washed three times with DMF to obtain a triblock metal organic framework heterojunction MH-3 with regular morphology and smooth surface.

[0063] Figure 1 The fluorescence images of three metal organic frameworks FJU-666, FJU-667 and FJU-668. Figure 1 It can be seen that under ultraviolet excitation, the metal organic framework FJU-666 exhibits yellow fluorescence, which is similar to the emission of the corresponding columnar ligand, indicating that the emission of the metal organic framework FJU-666 comes from the charge transfer ligand DPBD. Under ultraviolet excitation, the metal organic framework FJU-667 exhibits cyan fluorescence, which is similar to the emission of the corresponding columnar ligand, indicating that the emission of the metal organic framework FJU-667 comes from the charge transfer ligand DPA. Under ultraviolet excitation, the metal organic framework FJU-668 exhibits blue fluorescence, which is similar to the emission of the corresponding columnar ligand, indicating that the emission of the metal organic framework FJU-668 comes from the charge transfer ligand DPB.

[0064] Figure 2 The crystal structures of three metal organic frameworks FJU-666, FJU-667 and FJU-668. Figure 2 It can be seen that the three metal-organic frameworks show similar layer-column structures, which is conducive to the lattice matching of different metal-organic frameworks, thereby promoting the construction of metal-organic framework heterostructures.

[0065] Figure 3 The fluorescence images of the metal organic framework heterostructure MH-1 at different growth stages. Figure 3 It can be seen that in a typical preparation process, the yellow metal organic framework FJU-666 is quickly prepared by solvothermal reaction and can be used as a seed for the epitaxial growth of the cyan metal organic framework FJU-667. Then, the yellow metal organic framework FJU-666 is added to the prepared DPA, TCPE and zinc nitrate solution. After heating for 24 hours, a cyan-yellow-cyan triblock MOF heterostructure with the yellow metal organic framework FJU-666 as the middle segment and the cyan metal organic framework FJU-667 as the tip is obtained, showing the horizontal epitaxial growth of these MOF heterostructures. Interestingly, further increase above 24 hours can induce the longitudinal epitaxial growth of the cyan metal organic framework FJU-667 to form a core-shell metal organic framework heterojunction.

[0066] Figure 4 A is the fluorescence image of the metal organic framework heterostructure MH-1; B is the scanning electron microscope image of the metal organic framework heterostructure MH-1. Figure 4 It is shown that the metal-organic framework heterostructure MH-1 composed of yellow metal-organic framework FJU-666 and cyan metal-organic framework FJU-667 has a linear and smooth morphology and robust interfacial connection, which helps to provide high-security information presentation in the metal-organic framework heterostructure.

[0067] Figure 5 The fluorescence images of metal organic framework heterostructures MH-2 and MH-3 are shown in Figure 2. Figure 5 It can be seen that the blue metal-organic framework FJU-668 is assembled with the yellow metal-organic framework FJU-666 and the cyan metal-organic framework FJU-667 by horizontal epitaxial growth, which greatly enriches the color and information complexity of the metal-organic framework heterostructure.

[0068] Figure 6 The fluorescence images of the metal organic framework heterostructures MH-1, MH-2 and MH-3 under dichloromethane stimulation and volatilization. As shown in Figure A, the metal organic framework heterostructure MH-1 composed of the yellow metal organic framework FJU-666 and the cyan metal organic framework FJU-667 exhibits a distinct cyan-yellow-cyan emission pattern in its original state. After exposure to dichloromethane, the color changes to a cerulean-green-cerulean pattern. After dichloromethane volatilization, MH-1 returns to its original state and exhibits a reversible response emission pattern. This prompted us to replace the basic metal organic framework to adjust the response emission pattern of the heterostructure.

[0069] Then, the metal organic framework heterostructure MH-2 composed of yellow metal organic framework FJU-666 and blue metal organic framework FJU-668 and the metal organic framework FJU-668 heterostructure MH-3 composed of cyan metal organic framework FJU-667 and blue metal organic framework FJU-668 are shown in Figures B and C, respectively. Under the stimulation of dichloromethane, the initial blue-yellow-blue emission mode of MH-2 is transformed into a blue-green-blue mode with obvious regional control, and finally returns to the blue-yellow-blue mode after the dichloromethane evaporates; under the stimulation of dichloromethane, the initial blue-cyan-blue emission mode of MH-3 is rapidly transformed into a blue-cerulean-blue emission mode, and when the dichloromethane evaporates, it returns to the initial state again, indicating that these heterostructures have different response emission modes, which further enhances the information storage and presentation capabilities.

[0070] Figure 7The PL spectra of metal-organic framework heterostructures MH-1, MH-2, and MH-3 were used to encode and design robust anti-counterfeiting labels with high-security switching states. Figure 7 It can be seen that the responsive composite coding strategy is defined in Figure A. Taking MH-1 as an example, the spectra of all metal-organic frameworks are divided into four equal sections along the wavelength axis (400-600 nm), and the integrated area and midpoint of each section determine the width and position of the sub-barcode, respectively. Then, the sub-barcodes are compressed according to the length ratio of the metal-organic framework blocks to form the initial barcode-1, which is further reversibly converted into the covert barcode-2. In addition, the barcodes based on MH-2 and MH-3 (barcode-3, barcode-4, barcode-5, barcode-6) also have reversible coding performance, further expanding the coding diversity of covert photon barcodes.

[0071] Figure 8 Demonstration of photonic barcodes based on metal-organic framework heterostructures for anti-counterfeiting of artworks. Figure 8 As can be seen, the multicolor responsive photonic barcodes of the three metal-organic framework heterostructures inspire us to utilize them as robust anti-counterfeiting labels with multiple authentication. Figure 8 The concept in the illustration is that the three metal-organic framework heterostructures are embedded into an artwork by the manufacturer as a set of security tags. The corresponding initial (barcode I) and covert (barcode II) coding information are obtained according to the coding rules and entered into the cloud for reference. During the circulation of artworks, in step 1, the initial coding information (barcode III) of the tagged metal-organic framework heterostructure can be obtained through the encoder and entered into the computer for online retrieval. Only when barcode III is consistent with barcode I, the match will proceed to the next step of verification. In step 2, under the stimulation of dichloromethane, if the obtained covert coding information (barcode IV) matches the barcode II provided in the cloud, the evaluation result is correct, otherwise the work is counterfeit.

[0072] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a metal-organic framework heterojunction based on differentiated intra-ligand charge transfer, characterized in that: The following steps are involved: 1) dissolving organic ligand A, organic ligand TCPE and zinc nitrate in DMF at a molar ratio of 1:2:5; adding water and hydrochloric acid solution to the uniformly mixed solution, and ultrasonicating to obtain a mixed solution; putting the mixed solution into a glass bottle, placing it in an oven for heating, then taking it out and cooling it to room temperature, and washing it with DMF for 3 to 4 times to obtain a rod-shaped metal organic framework with regular morphology and smooth surface; 2) dissolving the organic ligand B, the organic ligand TCPE and zinc nitrate in DMF at a molar ratio of 1:2:5; adding water and hydrochloric acid solution to the uniformly mixed solution, ultrasonicating to obtain a mixed solution, placing the mixed solution and the metal organic framework prepared in step 1) into a glass bottle and heating it in an oven, then taking it out and cooling it to room temperature, washing it with DMF for 3 to 4 times, and obtaining a triblock metal organic framework heterojunction; The organic ligand A is any one of DPBD, DPA and DPB, the organic ligand B is DPA or DPB, and the organic ligand A and the organic ligand B are different from each other; Among them, DPBD is 3,6-dipyridine-4-tetraphenyl-1,2-diamine, DPA is 2,5-dipyridine-4-acylanilide, DPB is 1,4-dipyridine-4-alkylbenzene, and TCPE is tetracarboxytetraphenylethylene.

2. The method for preparing a metal organic framework heterojunction based on differentiated intra-ligand charge transfer according to claim 1, characterized in that: Step 1) The total amount of the organic ligand A, the organic ligand TCPE, the metal zinc nitrate and the organic solvent DMF is 8mmol:2-2.2ml; Step 1) The total amount of the organic ligand A, the organic ligand TCPE, the metal zinc nitrate, water, and the hydrochloric acid is in the ratio of 8mmol:1-1.1:ml:300-320μL.

3. The method for preparing a metal organic framework heterojunction based on differentiated intra-ligand charge transfer according to claim 1, characterized in that: Step 2) the total amount of the organic ligand B, the organic ligand TCPE, the metal zinc nitrate and the organic solvent DMF is 8mmol:2-2.2ml; Step 2) The total amount of the organic ligand B, the organic ligand TCPE, the metal zinc nitrate, water, and the hydrochloric acid is in the ratio of 8 mmol:1-1.1:ml:300-320 μL.

4. The method for preparing a metal organic framework heterojunction based on differentiated intra-ligand charge transfer according to claim 1, characterized in that: The ultrasonic time in step 1) and step 2) is 4.5 to 5.5 minutes, and the ultrasonic frequency is 55 to 65 kHz.

5. The method for preparing a metal organic framework heterojunction based on differentiated intra-ligand charge transfer according to claim 1, characterized in that: The heating temperature of the oven in step 1) and step 2) is 60 ～ 100°C, heating time is 24 to 48 hours, preferably heating at 80°C for 24 hours.

6. The method for preparing a metal organic framework heterojunction based on differentiated intra-ligand charge transfer according to claim 1, characterized in that: The organic ligand A is DPBD, and the organic ligand B is DPA.

7. The method for preparing a metal organic framework heterojunction based on differentiated intra-ligand charge transfer according to claim 1, characterized in that: The organic ligand A is DPBD, and the organic ligand B is DPB.

8. The method for preparing a metal organic framework heterojunction based on differentiated intra-ligand charge transfer according to claim 1, characterized in that: The organic ligand A is DPA, and the organic ligand B is DPB.

9. The metal organic framework heterojunction obtained according to the preparation method according to any one of claims 1 to 8.

10. Application of the metal organic framework heterojunction obtained by the preparation method according to any one of claims 1 to 8 in anti-counterfeiting.

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