Aggregation-induced emission metal-organic framework material and preparation method and application thereof

Abstract

The application discloses an aggregation-induced emission metal organic framework material and a preparation method and application thereof. The metal node in the aggregation-induced emission metal organic framework material is Zn 2+ , the organic linker is 1,2-di(4-carboxylphenyl)-1,2-stilbene or 4,4'-(2,2-diphenylethene-1,1-diyl)dibenzoic acid, and the preparation method comprises the following steps: dissolving a zinc salt and an organic ligand in an organic solvent to prepare a solution, the organic ligand is DCPE or DPEB, the pH value of the solution is adjusted to 3-5, and then a solvothermal reaction is carried out; and then, product separation, purification and drying are carried out. The aggregation-induced emission metal organic framework material has a low-symmetry framework structure, has the advantages of rapidness, convenience, good selectivity, high sensitivity and the like in the detection of maleic acid and fumaric acid, and the preparation method is simple, the synthesis purity is high, and the aggregation-induced emission metal organic framework material is suitable for large-scale industrial production and application.

Description

Technical Field

[0001] This invention relates to the field of fluorescence detection technology, specifically to an aggregation-induced emission metal-organic framework material, its preparation method, and its application. Background Technology

[0002] Olefin cis-trans isomers are widely found in nature and industrial processes. The physical, chemical, and biological properties of these isomers can vary significantly due to differences in double bond configurations. The detection of olefin cis-trans isomers is of great importance. For example, maleic acid and fumaric acid are common food additives and chemical intermediates, and the rapid differentiation and quantitative detection of their isomers are crucial for food safety and industrial quality control. Currently, methods for detecting olefin cis-trans isomers include chromatography and electrochemical methods, but these methods often suffer from drawbacks such as expensive equipment and complex operation, making it difficult to fully meet practical application requirements. Therefore, developing a simple, rapid, and highly sensitive method for detecting olefin cis-trans isomers is essential.

[0003] Metal-organic frameworks (MOFs) are a class of highly ordered porous materials formed by the self-assembly of metal ions or metal clusters with organic ligands through coordination bonds. They possess high specific surface area, tunable pore structure, and abundant functional modification sites, showing broad application prospects in gas storage, catalysis, and biosensing. Aggregation-induced emission (AIE) metal-organic frameworks are a type of MOF material exhibiting aggregation-induced emission activity. They combine the high fluorescence emission performance of AIE ligands with the advantages of MOF materials, providing new possibilities for efficient fluorescence sensing detection. However, due to the similar molecular weight and chemical properties of cis-trans isomers, efficient identification and detection of olefin cis-trans isomers still faces significant technical barriers. For example, Xu et al. reported a luminescent metal-organic framework based on tetraphenylethene that can be used for the detection of cis-trans isomers (Xu, Y.; Tao, C.-L.; Yu, M.; Xiong, Y.; Ouyang, Y.-N.; Liu, X.-G.; Zhao, Z. Tetraphenylethene-Based Luminescent Metal-Organic Framework for Effective Differentiation of cis / trans Isomers. ACS Appl. Mater. Interfaces 2020, 12, 35266-35272.). However, this metal-organic framework has a single structural recognition dimension, mainly relying on static pore size sieving, making it difficult to distinguish olefin cis-trans isomers with very small differences in molecular size and chemical properties. Furthermore, existing MOF material synthesis methods only control the pore size of MOF materials by empirically adjusting the ligand length, lacking precise design of the local chemical microenvironment of the framework and effective synthesis strategies. This limits the sensitivity, selectivity, and anti-interference ability of aggregation-induced emission metal-organic framework materials for the detection of olefin cis-trans isomers.

[0004] Therefore, it is of great significance to develop an aggregation-induced emission metal-organic framework material that can be used for efficient detection of olefin cis-trans isomers. Summary of the Invention

[0005] The purpose of this invention is to provide an aggregation-induced emission metal-organic framework material, its preparation method, and its application.

[0006] The technical solution adopted in this invention is:

[0007] An aggregation-induced emission metal-organic framework material, wherein the metal nodes are Zn 2+The organic linker is 1,2-bis(4-carboxyphenyl)-1,2-diphenylphenyl or 4,4'-(2,2-diphenylethylene-1,1-diyl)dibenzoic acid.

[0008] A method for preparing an aggregation-induced emission metal-organic framework material as described above includes the following steps: dissolving a zinc salt and an organic ligand in an organic solvent to form a solution, wherein the organic ligand is 1,2-bis(4-carboxyphenyl)-1,2-diphenyl styrene (DCPE) or 4,4'-(2,2-diphenylethylene-1,1-diyl)dibenzoic acid (DPEB), adjusting the pH of the solution to 3-5, then carrying out a solvothermal reaction, and then separating, purifying and drying the product to obtain the aggregation-induced emission metal-organic framework material.

[0009] Preferably, the molar ratio of the zinc salt to the organic ligand is 1:0.14 to 0.20.

[0010] Preferably, the ratio of zinc salt to organic solvent is 1 mmol: 30 mL to 60 mL.

[0011] Preferably, the zinc salt is at least one of zinc nitrate hexahydrate and zinc acetate tetrahydrate. The water of crystallization contained in zinc nitrate hexahydrate and zinc acetate tetrahydrate can significantly slow down the nucleation rate, which is beneficial to crystal growth. However, it is impossible to successfully synthesize metal-organic framework materials with good crystallinity using zinc salts that do not contain water of crystallization.

[0012] Preferably, the organic solvent is at least one of N,N-dimethylformamide, N,N-diethylformamide, and dimethyl sulfoxide.

[0013] Preferably, the pH adjustment reagent used to adjust the solution is an aqueous nitric acid solution.

[0014] Preferably, the concentration of the nitric acid aqueous solution is 4 mol / L to 8 mol / L.

[0015] Preferably, the solvothermal reaction is carried out at a temperature of 110℃ to 130℃ for a reaction time of 24h to 72h.

[0016] Preferably, the product separation, purification and drying include the following operations: transferring the product from the reaction solution to hot N,N-dimethylformamide for multiple solvent exchanges, washing with ethanol multiple times, and then drying.

[0017] Preferably, the temperature of the heated N,N-dimethylformamide is 60°C to 80°C.

[0018] Preferably, the drying is carried out at a temperature of 60℃ to 80℃ for a drying time of 7h to 10h.

[0019] An aggregation-induced emission metal-organic framework material as described above is used for the detection of maleic acid (cis-butenedioic acid) and fumaric acid (trans-butenedioic acid).

[0020] A method for detecting maleic acid and fumaric acid includes the following steps:

[0021] 1) Plotting the fluorescence intensity-maleic acid concentration relationship curves and the fluorescence intensity-fumaric acid concentration relationship curves:

[0022] Plotting the fluorescence intensity-maleic acid concentration curve: MOF-1 was dispersed in a solvent to prepare a MOF-1 dispersion, with Zn as the metal node in the MOF-1. 2+ The organic linker was 1,2-bis(4-carboxyphenyl)-1,2-diphenylene. Maleic acid was added in multiple portions, and the fluorescence spectrum of the dispersion was measured each time. The fluorescence intensity-maleic acid concentration relationship curve was then established based on the peak intensity in the fluorescence spectrum.

[0023] Plotting the fluorescence intensity-fumaric acid concentration curve: MOF-2 was dispersed in a solvent to prepare a MOF-2 dispersion, with Zn as the metal node in the MOF-2. 2+ The organic linker is 4,4'-(2,2-diphenylethylene-1,1-diyl)dibenzoic acid. Fumaric acid is added in multiple portions, and the fluorescence spectrum of the dispersion is measured each time. The fluorescence intensity-fumaric acid concentration relationship curve is established based on the peak intensity in the fluorescence spectrum.

[0024] 2) Prepare the sample to be tested into a solution, and then add it to MOF-1 dispersion and MOF-2 dispersion respectively. Measure the fluorescence spectrum of the dispersion, and then obtain the concentration of maleic acid / fumaric acid based on the fluorescence intensity-maleic acid / fumaric acid concentration relationship curve according to the fluorescence spectrum.

[0025] Preferably, the solvent in step 1) is at least one of ethanol and isopropanol.

[0026] Preferably, the concentration of the MOF-1 dispersion in step 1) is 0.3 mg / mL to 0.7 mg / mL.

[0027] Preferably, the concentration of the MOF-2 dispersion in step 1) is 0.3 mg / mL to 0.7 mg / mL.

[0028] Preferably, the fluorescence spectrum in step 1) is excited under excitation light with a wavelength of 365 nm.

[0029] Preferably, the concentration of the MOF-1 dispersion in step 2) is 0.3 mg / mL to 0.7 mg / mL.

[0030] Preferably, the concentration of the MOF-2 dispersion in step 2) is 0.3 mg / mL to 0.7 mg / mL.

[0031] Preferably, the fluorescence spectrum in step 2) is excited under excitation light with a wavelength of 365 nm.

[0032] Preferably, the MOF-1 dispersion in step 1) and the MOF-1 dispersion in step 2) have the same concentration.

[0033] Preferably, the MOF-2 dispersion in step 1) and the MOF-2 dispersion in step 2) have the same concentration.

[0034] The principle of this invention: This invention constructs an aggregation-induced emission metal-organic framework material with a low-symmetry framework structure by reducing ligand symmetry, and integrates isomer recognition sites into the framework. The resulting aggregation-induced emission metal-organic framework material can selectively recognize maleic acid and fumaric acid, thus enabling efficient detection of maleic acid and fumaric acid, significantly improving the selectivity and anti-interference ability of detection, and solving the problems of cumbersome methods, poor selectivity, and weak anti-interference ability of existing aggregation-induced emission metal-organic framework materials for the practical detection of olefin cis-trans isomers.

[0035] The beneficial effects of the present invention are: the aggregation-induced emission metal-organic framework material of the present invention has a low symmetry framework structure, which has the advantages of being rapid and simple, having good selectivity and high sensitivity for the detection of maleic acid and fumaric acid, and its preparation method is simple and has high synthesis purity, making it suitable for large-scale industrial production and application.

[0036] Specifically:

[0037] 1) The aggregation-induced emission metal-organic framework material of the present invention has a porous structure and aggregation-induced emission characteristics, and excellent fluorescence performance, providing the necessary conditions for fluorescence detection;

[0038] 2) The aggregation-induced emission metal-organic framework material of the present invention has a unique framework structure and active metal center, which can selectively recognize maleic acid and fumaric acid, greatly improving detection sensitivity and detection speed.

[0039] 3) The preparation method of the aggregation-induced emission metal-organic framework material of the present invention is simple and has high synthesis purity, making it suitable for large-scale industrial production and application;

[0040] 4) The method for detecting maleic acid and fumaric acid of the present invention has the advantages of simple operation, rapid reaction and low equipment requirements. This detection method is crucial for food safety and industrial quality control and has great practical application value. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the crystal structure of MOF-1.

[0042] Figure 2 This is a schematic diagram of the crystal structure of MOF-2.

[0043] Figure 3 The fluorescence spectrum of the dispersion containing MOF-1 and maleic acid is shown.

[0044] Figure 4 This is the fluorescence intensity-maleic acid concentration curve.

[0045] Figure 5 The fluorescence spectrum of the dispersion containing MOF-2 and fumaric acid is shown.

[0046] Figure 6 This is a curve showing the relationship between fluorescence intensity and fumaric acid concentration.

[0047] Figure 7 The fluorescence response diagrams of MOF-1 and MOF-2 to maleic acid and fumaric acid are shown.

[0048] Figure 8 The images show the color development of four types of starch under sunlight / ultraviolet light. Detailed Implementation

[0049] The present invention will be further explained and described below with reference to specific embodiments.

[0050] Example:

[0051] Preparation of MOF-1 and MOF-2:

[0052] a) Preparation of MOF-1:

[0053] An aggregation-induced emission metal-organic framework material is prepared by the following method:

[0054] 0.084 mmol of zinc acetate tetrahydrate, 0.014 mmol of DCPE, and 100 μL of 6 mol / L nitric acid aqueous solution were added to 4 mL of N,N-diethylformamide. The mixture was ultrasonically dispersed for 5 min and then placed in an oven at 120 °C for 72 h. After cooling to room temperature (light yellow prismatic crystals precipitated), the product was transferred from the reaction solution to N,N-dimethylformamide preheated to 60 °C for three solvent exchanges. The product was then washed twice with ethanol and placed in a vacuum oven at 80 °C for 8 h to obtain an aggregation-induced emission metal-organic framework material (denoted as MOF-1).

[0055] Single-crystal structure analysis of aggregation-induced emission metal-organic framework (MOF-1):

[0056] Single crystals of suitable size were selected for single-crystal X-ray diffraction under a microscope. The crystal structure parameters of MOF-1 obtained are as follows: triclinic system. P 1. Space group a =19.0506(2)Å, b =19.2076(2)Å, c =19.4202(3)Å, α =94.6300(10) ° , β =99.2180(10) ° , γ =91.3110(10) ° The structure contains two similar asymmetric structural units: one consisting of a Zn4O metal unit, three DCPE molecules, and two coordinated water molecules, and the other consisting of a Zn4O metal unit, three DCPE molecules, a coordinated DEF, and a coordinated water molecule. Slightly different from the classic Zn4O(COO)6, this structure contains two modified tetranuclear metal nodes: Zn4O(COO)6(DMF)(H2O) and Zn4O(COO)6(DMF)2. Zn1, Zn2, and Zn3 are tetracoordinated, each connecting two carboxyl groups; Zn4 is hexacoordinated, connecting two carboxyl groups and two coordinated water molecules; Zn5, Zn6, and Zn7 are also tetracoordinated; and Zn8 has a hexacoordinated octahedral coordination geometry, coordinating with four carboxyl oxygen atoms, one DEF molecule, one water molecule, four Zn4O nodes, and eight DCPEs to form cubic building blocks. These building blocks share metal nodes, thus forming a three-dimensional framework structure. The three-dimensional framework composed of the two different structural units interpenetrates through their respective channels, forming an interpenetrating structure. (A schematic diagram of the MOF-1 crystal structure obtained after structural analysis and refinement is shown below.) Figure 1 As shown in the figure, a and b are two types of asymmetric structural units, c is a molecular building block, and d is a three-dimensional structure diagram.

[0057] b) Preparation of MOF-2:

[0058] An aggregation-induced emission metal-organic framework material is prepared by the following method:

[0059] 0.084 mmol of zinc nitrate hexahydrate, 0.014 mmol of DPEB and 100 μL of 6 mol / L nitric acid aqueous solution were added to 4 mL of N,N-diethylformamide. The mixture was ultrasonically dispersed for 5 min and then placed in an oven at 120 °C for 24 h. After cooling to room temperature (colorless rod-shaped crystals precipitated), the product was transferred from the reaction solution to N,N-dimethylformamide preheated to 60 °C for three solvent exchanges. The product was then washed twice with ethanol and placed in a vacuum oven at 80 °C for 8 h to obtain an aggregation-induced emission metal-organic framework material (denoted as MOF-2).

[0060] Single-crystal structure analysis of aggregation-induced emission metal-organic framework (MOF-2):

[0061] Single crystals of suitable size were selected for single-crystal X-ray diffraction under a microscope. The crystal structure parameters of MOF-2 obtained are as follows: monoclinic system. C 2 / c Space group, a =23.8191(10)Å, b =41.6687(14)Å, c =6.1178(2)Å, β =94.683(3) ° The asymmetric structural unit contains 1.5 Zn ions, one DPEB molecule, and one OH ion. The three Zn ions share a single OH ion, forming a Zn3OH cluster metal node. These metal nodes form a one-dimensional rod-shaped SBU with shared vertices. These SBUs are connected by DPEB ligands, thus forming a two-dimensional layered structure. These two-dimensional layers are stacked in space in a -AAAA- pattern. π-π interactions and CH…π interactions exist between the benzene rings of the layers, further extending into a three-dimensional supramolecular structure. ab The planar structure formed a channel structure of approximately 6.11 Å × 17.81 Å (see schematic diagram of the MOF-2 crystal structure obtained after structural analysis and refinement). Figure 2 As shown in the figure, a is an asymmetric structural unit, b is a secondary structural unit, c is a molecular building block, and d is a stacking diagram of two-dimensional layers.

[0062] Detection of maleic acid and fumaric acid:

[0063] A method for detecting maleic acid and fumaric acid, comprising the following steps:

[0064] 1) Plotting the fluorescence intensity-maleic acid concentration relationship curves and the fluorescence intensity-fumaric acid concentration relationship curves:

[0065] Plotting the fluorescence intensity-maleic acid concentration curve: MOF-1 was ultrasonically dispersed in ethanol to prepare a MOF-1 dispersion with a concentration of 0.5 mg / mL. Then, 3 mL of the MOF-1 dispersion was added to maleic acid in multiple portions, and the fluorescence spectrum of the dispersion was measured each time under excitation light at a wavelength of 365 nm (e.g., Figure 3 As shown, the concentration range of maleic acid is 0 μM to 75 μM. Then, a fluorescence intensity-maleic acid concentration relationship curve is established based on the peak intensity in the fluorescence spectrum (e.g., ...). Figure 4 (as shown)

[0066] Plotting the fluorescence intensity-fumaric acid concentration curve: MOF-2 was ultrasonically dispersed in ethanol to prepare a MOF-2 dispersion with a concentration of 0.5 mg / mL. Then, 3 mL of the MOF-2 dispersion was added to fumaric acid in multiple portions, and the fluorescence spectrum of the dispersion was measured each time under excitation light at a wavelength of 365 nm (e.g., fumaric acid concentration). Figure 5 As shown, the concentration range of fumaric acid is 0 μM to 75 μM. Then, a fluorescence intensity-fumaric acid concentration relationship curve is established based on the peak intensity in the fluorescence spectrum (e.g., ...). Figure 6 (as shown)

[0067] 2) 100 μL of 0.1 mM maleic acid aqueous solution and 0.1 mM fumaric acid aqueous solution were used as simulated test samples and added to 0.5 mg / mL MOF-1 dispersion and 0.5 mg / mL MOF-2 dispersion, respectively. The fluorescence spectra of the dispersions were measured under excitation light at a wavelength of 365 nm. The concentrations of maleic acid / fumaric acid were then obtained based on the fluorescence intensity-maleic acid / fumaric acid concentration relationship curve (the fluorescence response diagrams of MOF-1 and MOF-2 to maleic acid and fumaric acid are shown in Figure 1). Figure 7 As shown in the figure, cis-COOH represents maleic acid, and trans-COOH represents fumaric acid.

[0068] Depend on Figure 3 and Figure 4 It can be seen that as maleic acid is continuously added, the fluorescence intensity of the dispersion gradually decreases. When the concentration of maleic acid in the dispersion reaches 75 μM, the fluorescence is almost completely quenched. When the concentration of maleic acid in the dispersion is below 3.5 μM, the fluorescence intensity of the dispersion changes linearly with the concentration of maleic acid. The calculated K0 value indicates this. sv =9.40×10 4 M -1 The lowest detection limit was calculated to be 1.30 ppm based on the SV equation.

[0069] Depend on Figure 5 and Figure 6It can be seen that as fumaric acid is continuously added, the fluorescence intensity of the dispersion gradually decreases. When the concentration of fumaric acid in the dispersion reaches 75 μM, the fluorescence is almost completely quenched. When the concentration of fumaric acid in the dispersion is below 3.5 μM, the fluorescence intensity of the dispersion changes linearly with the concentration of fumaric acid. The calculated K0 value indicates this. sv =1.41×10 5 M -1 The lowest detection limit was calculated to be 846 ppb based on the SV equation.

[0070] Depend on Figure 7 It can be seen that maleic acid (cis configuration) quenches MOF-1 to a much greater extent than fumaric acid (trans configuration). Conversely, fumaric acid (trans configuration) quenches MOF-2 to a much greater extent than maleic acid (cis configuration). This indicates that MOF-1 has a specific recognition ability for maleic acid and its detection will not be interfered with by fumaric acid. In contrast, MOF-2 has a specific recognition ability for fumaric acid and its detection will not be interfered with by maleic acid.

[0071] In summary, the aggregation-induced emission metal-organic framework material of the present invention can selectively identify maleic acid and fumaric acid, and has the advantages of being rapid, simple, selective, and sensitive for the detection of maleic acid and fumaric acid.

[0072] Application example:

[0073] A method for detecting maleic acid and fumaric acid, comprising the following steps:

[0074] Four commercially available starches (corn starch, potato starch, wheat starch, and sweet potato starch) were added to well plates, with eight wells per group. Two wells contained 600 ppm maleic acid, and two wells contained 600 ppm fumaric acid to simulate the maximum permissible additive dosage. The remaining four wells contained unadulterated starch. Then, 50 μL of either a 0.5 mg / mL MOF-1 dispersion or a 0.5 mg / mL MOF-2 dispersion was added to each well. The plates were then dried in an oven and photographed under sunlight and a 365 nm UV lamp. The color development of the four starches under sunlight / UV lamp is shown below. Figure 8 (A shows the color development of corn starch and potato starch under sunlight, B shows the color development of corn starch and potato starch under ultraviolet light, C shows the color development of wheat starch and sweet potato starch under sunlight, and D shows the color development of wheat starch and sweet potato starch under ultraviolet light.)

[0075] Depend on Figure 8It can be seen that after adding MOF dispersion, all four types of starch exhibited obvious fluorescence emission; the fluorescence of the starch sample mixed with fumaric acid with MOF-1 showed no obvious change, while the fluorescence of the starch sample mixed with maleic acid was significantly quenched; conversely, the fluorescence of the starch sample mixed with fumaric acid with MOF-2 was significantly quenched, while the fluorescence of the starch sample mixed with maleic acid showed no obvious change. These results indicate that MOF-1 and MOF-2 have the potential to detect the corresponding additives (maleic acid and fumaric acid) in actual starch samples.

[0076] In addition, by dissolving the above four types of starch in water to prepare a test solution, and then performing the concentration test of maleic acid and fumaric acid according to the method in the example, the content of maleic acid and fumaric acid in the four types of starch can be quickly and accurately determined.

[0077] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for detecting maleic acid and fumaric acid, characterized by, Comprising the following steps: 1) Preparation of fluorescence intensity-maleic acid concentration curve and fluorescence intensity-fumaric acid concentration curve: Preparation of the fluorescence intensity-maleic acid concentration relationship curve: the aggregation-induced emission metal organic framework material MOF-1 is dispersed in a solvent to prepare a MOF-1 dispersion liquid, and the metal node in the MOF-1 is Zn 2+ , the organic linker is 1,2-bis(4-carboxylphenyl)-1,2-diphenyl ethylene, and the maleic acid is added in multiple times, the fluorescence spectrum of the dispersion liquid is measured each time, and the fluorescence intensity-maleic acid concentration relationship curve is established according to the peak intensity in the fluorescence spectrum; Preparation of fluorescence intensity-fumaric acid concentration relationship curve: the aggregation-induced emission metal organic framework material MOF-2 is dispersed in a solvent to prepare a MOF-2 dispersion liquid, and the metal node in the MOF-2 is Zn 2+ , the organic linker is 4,4'-(2,2-diphenyl ethylene-1,1-diyl) dibenzoic acid, and the fumaric acid is added in multiple times, the fluorescence spectrum of the dispersion liquid is measured each time, and the fluorescence intensity-fumaric acid concentration relationship curve is established according to the peak intensity in the fluorescence spectrum; 2) The sample to be tested is prepared into a solution, then added into MOF-1 dispersion and MOF-2 dispersion respectively, and the fluorescence spectrum of the dispersion is measured, and then the concentration of maleic acid / fumaric acid is obtained according to the fluorescence spectrum and the fluorescence intensity-maleic acid / fumaric acid concentration curve.

2. The method of detecting maleic acid and fumaric acid according to claim 1, characterized by: The MOF-1 in step 1) is prepared by a preparation method comprising the following steps: dissolving a zinc salt and an organic ligand into an organic solvent to prepare a solution, the organic ligand being 1,2-di(4-carboxyphenyl)-1,2-stilbene, adjusting the pH value of the solution to 3-5, then carrying out a solvothermal reaction, and then carrying out product separation, purification and drying to obtain the aggregation-induced emission metal organic framework material MOF-1.

3. The method of detecting maleic acid and fumaric acid according to claim 2, characterized in that: The molar ratio of the zinc salt to the organic ligand is 1:0.14-0.

20.

4. The method of detecting maleic acid and fumaric acid according to claim 2 or 3, characterized in that: The zinc salt is at least one of zinc nitrate hexahydrate and zinc acetate tetrahydrate.

5. The method of detecting maleic acid and fumaric acid according to claim 2 or 3, characterized in that: The organic solvent is at least one of N,N-dimethylformamide, N,N-diethylformamide and dimethyl sulfoxide.

6. The method of detecting maleic acid and fumaric acid according to claim 2 or 3, characterized by: The solvothermal reaction is carried out at a temperature of 110-130°C, and the reaction time is 24-72h.

7. The method of detecting maleic acid and fumaric acid according to claim 2 or 3, characterized by: The product separation, purification and drying comprise the following operations: transferring the product from the reaction solution into hot N,N-dimethylformamide for multiple times of solvent exchange, then washing with ethanol for multiple times, and then drying.

8. The method of detecting maleic acid and fumaric acid according to claim 1, characterized by: The MOF-2 in step 1) is prepared by a preparation method comprising the following steps: dissolving a zinc salt and an organic ligand into an organic solvent to prepare a solution, the organic ligand being 4,4'-(2,2-diphenylvinyl-1,1-diyl)dibenzoic acid, adjusting the pH value of the solution to 3-5, then carrying out a solvothermal reaction, and then carrying out product separation, purification and drying to obtain the aggregation-induced emission metal organic framework material MOF-2.

9. The method of detecting maleic acid and fumaric acid according to claim 8, characterized in that: The molar ratio of the zinc salt to the organic ligand is 1:0.14-0.

20.

10. The method of detecting maleic acid and fumaric acid according to claim 8 or 9, characterized in that: The zinc salt is at least one of zinc nitrate hexahydrate and zinc acetate tetrahydrate.

11. The method of detecting maleic acid and fumaric acid according to claim 8 or 9, characterized in that: The organic solvent is at least one of N,N-dimethylformamide, N,N-diethylformamide and dimethyl sulfoxide.

12. The method of detecting maleic acid and fumaric acid according to claim 8 or 9, characterized in that: The solvothermal reaction is carried out at a temperature of 110-130°C, and the reaction time is 24-72h.

13. The method of detecting maleic acid and fumaric acid according to claim 8 or 9, characterized in that: The product separation, purification and drying comprise the following operations: transferring the product from the reaction solution into hot N,N-dimethylformamide for multiple times of solvent exchange, then washing with ethanol for multiple times, and then drying.

14. The method of detecting maleic acid and fumaric acid of claim 1, wherein: The concentration of the MOF-1 dispersion solution in step 1) is 0.3 mg / mL to 0.7 mg / mL; the concentration of the MOF-2 dispersion solution in step 1) is 0.3 mg / mL to 0.7 mg / mL; the concentration of the MOF-1 dispersion solution in step 2) is 0.3 mg / mL to 0.7 mg / mL; the concentration of the MOF-2 dispersion solution in step 2) is 0.3 mg / mL to 0.7 mg / mL; the concentration of the MOF-1 dispersion solution in step 1) is the same as that of the MOF-1 dispersion solution in step 2); and the concentration of the MOF-2 dispersion solution in step 1) is the same as that of the MOF-2 dispersion solution in step 2).

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