A fluorescent composite material, thin film and preparation and application thereof

Abstract

The present application relates to a kind of fluorescent composite, film and its preparation and application, by weak fluorescent material is dispersed in metal organic framework can be prepared with porous structure's solid-state fluorescent film, improve the luminescent performance of weak fluorescent material, expand its application range.Simultaneously the continuous pore of fluorescent MOF material inside provides space for guest molecule invasion, captures guest molecule in pore not only increases the opportunity of guest and host interaction, and also can enrich guest molecule, has potential application prospect in gas sensor aspect.

Description

Technical Field

[0001] This invention belongs to the field of functional materials, and specifically relates to a fluorescent composite material, a thin film, and its preparation and application. Background Technology

[0002] High-performance trace hazardous gas sensors are urgently needed in various fields such as national defense, environmental monitoring, and public health. Thin-film fluorescent sensors, due to their advantages of high sensitivity, fast response, and ease of device fabrication, hold promise for widespread application in gas sensing. However, the development of organic thin-film fluorescent sensing materials lags far behind that of solution-phase fluorescent sensing materials. The range of fluorescent materials applicable to gas-phase detection and the types of gases that can be detected are far fewer than those applicable to solution-phase detection and the types of analytes.

[0003] The main reason why thin-film fluorescence sensing research lags behind solution-phase sensing research is that most fluorescence sensing materials exhibit fluorescence aggregation-induced quenching. Therefore, many materials that exhibit good luminescence performance and sensing effects in solution show very weak luminescence after being fabricated into thin films due to the aggregation-induced quenching effect, making them difficult to use for gas-phase detection.

[0004] To develop fluorescent sensing materials for gas-phase detection, some existing technologies have focused on designing and synthesizing aggregation-induced emission (AIE) materials. However, the variety of AIE materials is limited, mainly consisting of a few types of materials with restricted structures, such as tetraphenylethylene, tetraphenylthiophene, and salicylaldehyde imide, which significantly restricts their application. Furthermore, the performance of fluorescent thin-film sensor materials is closely related to their aggregated morphology; porous structures greatly enhance the sensing efficiency of thin-film fluorescent sensors. Finding a method to apply materials with weak solid-state fluorescence to gas-phase detection and effectively control their aggregated morphology would undoubtedly greatly promote the development of thin-film fluorescent sensors. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a fluorescent composite material, a thin film, and its preparation and application, thereby addressing the technical problem that existing fluorescent sensing materials, when prepared into thin films, emit weak light due to aggregation-induced quenching, making them unsuitable for gas-phase detection. Simultaneously, this invention aims to address how to control the aggregation morphology of the fluorescent sensing material to form a porous structure, thereby promoting improved fluorescence sensing performance.

[0006] The present invention provides a fluorescent material, the structural formula of which is shown below:

[0007]

[0008] The preparation method of the fluorescent material includes: mixing Me4BOPHY, diethylamino-p-benzaldehyde and p-TsOH, adding solvent (a mixed solution of toluene and piperidine), and continuously stirring and heating in an oil bath at 140°C until the solvent evaporates to dryness. After the reaction stops, the mixture is purified to obtain the fluorescent material. The molar ratio of Me4BOPHY, diethylamino-p-benzaldehyde and p-TsOH is 1:1.2~1.5:0.05~0.2.

[0009] The purification process specifically involves: diluting and dissolving the mixture in dichloromethane to completely dissolve the black substance in the double-necked flask, washing it three times with water, extracting the aqueous phase with dichloromethane, drying and filtering the combined organic phases with anhydrous MgSO4, removing the organic solvent by vacuum evaporation, separating the phases by column chromatography with silica gel, and then recrystallizing the mixture by diffusing cyclohexane in a concentrated tetrahydrofuran solution.

[0010] The present invention provides a fluorescent composite material, the composite material comprising the fluorescent material and metal-organic frameworks (MOFs); the structure of the metal-organic frameworks (MOFs) is as follows: The fluorescent material is

[0011] Furthermore, the fluorescent composite material is a fluorescent material encapsulated by metal-organic frameworks (MOFs); wherein the mass ratio of the fluorescent material to the reactant 2-methylimidazole of the metal-organic framework is 1:492-20:492.

[0012] The present invention provides a method for preparing a fluorescent composite material, comprising: dispersing fluorescent material into a metal-organic framework structure to obtain a fluorescent composite material, namely a solid-state luminescent fluorescent sensing material.

[0013] More specifically, a method for preparing a fluorescent composite material according to the present invention includes:

[0014] The fluorescent material, nano-zinc oxide, and 2-methylimidazole were mixed, sealed, and reacted to obtain a fluorescent composite material. The mass ratio of the fluorescent material to 2-methylimidazole was 1:492-20:492; the mass ratio of the nano-zinc oxide to 2-methylimidazole was 162:492; the average particle size of the nano-zinc oxide was <50 nm; the reaction was carried out at a temperature of 100℃~120℃ for 21h~26h.

[0015] The present invention provides a fluorescent composite film, wherein the film is formed on a substrate containing the fluorescent composite material.

[0016] A method for preparing a fluorescent composite film according to the present invention includes:

[0017] The fluorescent composite material is dissolved in an organic solvent and then formed into a film on a substrate to obtain a fluorescent composite film. The organic solvent is at least one of tetrahydrofuran, dichloromethane, chloroform, toluene, and acetone; the substrate is a transparent substrate. Further, the transparent substrate is one of a glass substrate, a quartz substrate, an organic polymer solid support substrate, a transparent substrate, or a composite substrate composed of ultrathin metal oxides.

[0018] The concentration of the fluorescent composite material dissolved in the organic solvent is 1 mg / ml-5 mg / ml; the film formation method is at least one of spin coating, drop coating, and dip coating.

[0019] A sensor according to the present invention includes the fluorescent composite material film.

[0020] The present invention relates to the application of the sensor in gas phase detection, wherein the thin-film sensor for gas phase detection can be used to detect gases, wherein the gases include volatile organic compounds, narcotic gases, simulant gases, organic amine gases, hydrogen peroxide gases, nerve agent gases, or trace explosive volatile gases.

[0021] This application provides a method for improving the sensing performance of fluorescent sensitive materials and its application in gas sensors. The method for improving performance includes the following steps: obtaining a fluorescent probe material; dispersing the fluorescent probe material into a metal-organic framework structure to obtain a solid-state luminescent fluorescent sensing material; dissolving the sensing material in an organic solvent and preparing a fluorescent sensing film on a transparent substrate; the fluorescent sensing film can be used for gas phase detection.

[0022] This invention enables the preparation of porous solid-state fluorescent films by dispersing weakly fluorescent materials within a metal-organic framework (MOF), thereby improving the luminescence performance of these materials and expanding their application range. Simultaneously, the continuous pores within the fluorescent MOF provide space for guest molecules to invade. Capturing guest molecules within these pores not only increases the opportunity for interaction between the guest and the host but also allows for the enrichment of guest molecules, showing potential applications in gas sensors.

[0023] Beneficial effects

[0024] This invention synthesizes excellent fluorescent sensing probes by combining metal-organic frameworks (MOFs) with fluorescent sensing materials. MOFs provide various nanocavities for confining guest molecules, and the luminescence properties of the fluorescent molecules can be adjusted by the addition ratio. Selective recognition is achieved using organic fluorescent molecules. By applying the MOF framework to disperse the fluorescent molecules, aggregation-induced quenching effects can be effectively overcome, significantly improving the fluorescence quantum efficiency of the molecules and achieving solid-state emission while enhancing photostability. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating a method for improving the sensing performance of a fluorescent sensitive material according to an embodiment of this application;

[0026] Figure 2 The scanning electron microscope image (a) and X-ray diffraction pattern (b) of the metal-organic framework material loaded with fluorescent probes in Example 1 of this application are shown.

[0027] Figure 3 These are fluorescence images of the raw materials and the metal-organic framework material loaded with fluorescent probes in Example 1 of this application under a UV lamp; Figure 4 The fluorescence intensity of the encapsulated fluorescent sensing film in Example 1 of this application at its excitation wavelength of 490 nm is shown in the DCP.

[0028] Graphs showing changes in steam and SEM characterization;

[0029] Figure 5 The graph shows the change in fluorescence intensity of the coated fluorescent sensing film at its excitation wavelength of 490 nm in DCP vapor and its SEM characterization. (Example 2 of this application)

[0030] Figure 6 The graph shows the change in fluorescence intensity of the coated fluorescent sensing film at its excitation wavelength of 490 nm in DCP vapor and its SEM characterization.

[0031] Figure 7 The graph shows the change in fluorescence intensity of the coated fluorescent sensing film at its excitation wavelength of 490 nm in DCP vapor and its SEM characterization.

[0032] Figure 8 The graph shows the change in fluorescence intensity of the coated fluorescent sensing film at its excitation wavelength of 490 nm in DCP vapor and its SEM characterization. (Example 5 of this application)

[0033] Figure 9 The graph shows the change in fluorescence intensity of the coated fluorescent sensing film in DCP vapor at its excitation wavelength of 490 nm in Example 6 of this application, along with its SEM characterization. Detailed Implementation

[0034] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0035] Please see Figure 1, Figure 1 This application provides a method for improving the sensing performance of a fluorescence-sensitive material. The preparation method includes the following steps:

[0036] S1: Acquire fluorescence sensing material;

[0037] S2: A hybrid material is obtained by encapsulating fluorescent sensing materials and metal-organic framework structures in a set ratio;

[0038] S3: Dissolve the mixed material in the good organic solvent tetrahydrofuran to obtain a fluorescent sensing suspension;

[0039] S4: Fluorescent sensing probes are prepared by spin-coating a fluorescent sensing suspension onto a quartz substrate.

[0040] The fluorescent sensing probe prepared by this method can be used for gas phase detection.

[0041] In this embodiment of the application, the organic fluorescent sensing material can be a first compound;

[0042]

[0043] The structural formula of the first compound is:

[0044] The preparation method of the first compound is as follows: Fluoroboropyrrole (Me4BOPHY) (338 mg, 1 mmol), diethylamino-p-benzaldehyde (213 mg, 1.2 equivalents), and p-toluenesulfonic acid p-TsOH (10 mg) were placed in a double-necked flask. A magnetic stir bar was added, followed by a mixed solution of toluene and piperidine (2 mL). The mixture was heated in a fume hood with an oil bath at 140 °C with continuous stirring until the solvent evaporated to dryness. After the reaction was stopped, the mixture was diluted and dissolved in dichloromethane to completely dissolve the black substance in the double-necked flask, and washed three times with water. The aqueous phase was extracted with dichloromethane. The combined organic phases were dried over anhydrous MgSO4 and filtered, and the organic solvent was removed by evaporation under reduced pressure. The mixture was separated by column chromatography using silica gel, and then recrystallized by diffusion of cyclohexane in concentrated tetrahydrofuran solution to obtain the pure first compound. 1 H NMR(500MHz,Chloroform-d)δ7.89(s,1H),7.77(s,1H),7.37(d,J=8.5Hz,2H),7.17–7.05(m,2H),6.64(s,1H),6. 58(d,J=8.6Hz,2H),6.10(s,1H),3.34(q,J=7.1Hz,4H),2.43(s,3H),2.27(d,J=8.5Hz,6H),1.13(t,J=7.1Hz,6H). 13C NMR(101MHz,Chloroform-d)δ151.93,150.13,148.72,139.91,137.99,133.70,132.22,129.34 ,123.32,118.20,114.61,112.31,111.47,77.22,44.49,14.09,12.66,11.20,11.09.MALDI-TOF MS for C25H29B2F4N5:calcd,497.2545; found,497.2644.

[0045] In the embodiments of this application, the metal-organic framework structure includes a second compound.

[0046] The structural formula of compound 2 is:

[0047]

[0048] The preparation method of the second compound is as follows: 162 mg of nano-zinc oxide and 492 mg of 2-methylimidazole were mixed and added to a 10 ml glass bottle. The sealed glass bottle was placed in an oven at 110°C for one day. The reaction product was washed three times by centrifugation with DMF and methanol solvents, and finally dried in an oven at 60°C to obtain the second compound.

[0049] In this embodiment, the reaction mass ratio of the fluorescent sensing material and 2-methylimidazole is 1:492-20:492. Here, 1:492 and 20:492 are not two extreme values, but only a reference value. For specific materials, the optimal doping ratio needs to be optimized individually. For example, when the coating ratio of the fluorescent sensing material is small, it is closer to the solution state, which can obtain a higher fluorescence quantum efficiency, but will not obtain excellent sensing effect. When the coating ratio of the material is large, the fluorescence quantum efficiency is lower, but it can have a better sensing effect. The coating ratio can be determined according to the specific situation.

[0050] In this embodiment, the organic solvent can be any one of tetrahydrofuran, dichloromethane, chloroform, toluene, or acetone. The mixed material obtained by encapsulating the fluorescent sensing material and the metal-organic framework structure is dissolved in the above solvent, and its concentration range can be 1 mg / ml-5 mg / ml. In practice, the concentration of the solution can be adjusted according to the properties of different materials to obtain optimal performance.

[0051] In the embodiments of this application, the transparent substrate can be any one of glass substrate, quartz substrate, organic polymer solid carrier substrate, transparent substrate or composite substrate composed of ultrathin metal oxide.

[0052] In the embodiments of this application, the solution film formation method includes spin coating film formation method, drop coating film formation method, or dip coating film formation method.

[0053] This application embodiment prepares a fluorescent sensing film by synthesizing a metal-organic framework (MOF) with a fluorescent sensing material. The MOF can provide various nanocavities for confining guest molecules, and the luminescence properties of the fluorescent molecules can be adjusted by the addition ratio. Selective recognition is achieved using organic fluorescent molecules. By applying the MOF framework to disperse the fluorescent molecules, the aggregation-induced quenching effect can be effectively overcome, significantly improving the fluorescence quantum efficiency of the molecules, achieving solid-state emission while enhancing photostability.

[0054] This application also provides a gas phase sensor application, including a fluorescent sensing film prepared by the above preparation method. The gas phase sensor has high sensitivity to gases and can be used to detect gases.

[0055] In the embodiments of this application, the gas may be an organic volatile gas, an organic amine gas, hydrogen peroxide gas, a drug gas, a nerve agent gas, a simulant gas, or a trace explosive volatile gas.

[0056] Example 1

[0057] S1: Fluorescent sensing material (i.e., the first compound);

[0058] S2: The first compound, nano zinc oxide (product name: Zinc oxide nanoparticle ink, brand: Aldrich, supplier: Sigma-Aldrich (Shanghai) Trading Co. Ltd., average particle size: 8-16nm), and 2-methylimidazole were sealed in a mass ratio of 1:162:492, heated at 110°C for one day, and then centrifuged and washed to obtain mixed material Z1;

[0059] S3: Dissolve the mixed material Z1 in the good organic solvent tetrahydrofuran to obtain a fluorescent sensing suspension with a concentration of 3 mg / ml;

[0060] S4: A fluorescent sensing thin film is prepared on a quartz substrate by spin coating of a fluorescent sensing suspension. The length and width of the quartz substrate can be selected as 2cm × 1cm.

[0061] like Figure 2 The image shows a scanning electron microscope image and a powder XRD pattern of the metal-organic framework material loaded with fluorescent probes, indicating that the ZIF-8 structure has been successfully formed, realizing a basic framework for molecular dispersion.

[0062] like Figure 3The images shown are fluorescence images of the original and enhanced fluorescent sensing materials under ultraviolet light, respectively. Figure 3 As shown, the original fluorescent sensing material does not fluoresce under fluorescent light, but after being coated, the fluorescent sensing material emits bright pink fluorescence under ultraviolet light.

[0063] like Figure 4 The image shows the fluorescence intensity of the coated fluorescent sensing film at its excitation wavelength of 490 nm in DCP vapor and its SEM characterization. The test method is as follows: A small amount of diethyl chlorophosphate (DCP) is dropped into the bottom of a sealed quartz cell, and the fluorescence...

[0064] A photosensitive thin film was placed in a sealed quartz cell, and the change in its fluorescence emission spectrum under 490 nm excitation light over time was measured. For example... Figure 4 As shown, the fluorescence spectrum of the thin film in a DCP atmosphere is enhanced at 538 nm and quenched at 600 nm, consistent with the liquid-phase sensing of the raw material. In contrast, the original fluorescent sensing material's thin film does not emit light and cannot be used for gas-phase detection. This demonstrates that the fluorescent sensing thin film prepared by the method for improving the sensing performance of fluorescent sensitive materials provided in this application can enable gas-phase detection of materials that cannot be applied to solid-state sensing.

[0065] Example 2

[0066] S1: Fluorescent sensing material (i.e., the first compound);

[0067] S2: The first compound, nano zinc oxide (product name: Zinc oxide nanoparticle ink, brand: Aldrich, supplier: Sigma-Aldrich (Shanghai) Trading Co. Ltd., average particle size: 8-16nm) and 2-methylimidazole were sealed in a mass ratio of 2:162:492, heated at 110℃ for one day, and then centrifuged and washed to obtain the mixed material Z2.

[0068] S3: Dissolve the mixed material Z2 in the good organic solvent tetrahydrofuran to obtain a fluorescent sensing suspension with a concentration of 3 mg / ml;

[0069] S4: A fluorescent sensing thin film is prepared on a quartz substrate by spin coating of a fluorescent sensing suspension. The length and width of the quartz substrate can be selected as 2cm × 1cm.

[0070] like Figure 5The image shows the fluorescence intensity of the coated fluorescent sensing film at an excitation wavelength of 490 nm in DCP vapor and its SEM characterization. The test method is as follows: a small amount of DCP was dropped into the bottom of a sealed quartz cell, and the fluorescent sensing film was placed in the sealed quartz cell. The fluorescence emission spectrum under 490 nm excitation light was measured over time. The fluorescence of the film increased by 150% within 5 minutes in the DCP atmosphere, indicating excellent sensing performance. Compared to the 1:492 ratio synthesis in Example 1, the 2:492 ratio synthesis showed better results, indicating that different synthesis ratios may have different effects on sensing performance.

[0071] Example 3

[0072] S1: Fluorescent sensing material (i.e., the first compound);

[0073] S2: The first compound, nano zinc oxide (product name: Zinc oxide nanoparticle ink, brand: Aldrich, supplier: Sigma-Aldrich (Shanghai) Trading Co. Ltd., average particle size: 8-16nm), and 2-methylimidazole were sealed in a mass ratio of 5:162:492, heated at 110°C for one day, and then centrifuged and washed to obtain mixed material Z3;

[0074] S3: Dissolve the mixed material Z3 in the good organic solvent tetrahydrofuran to obtain a fluorescent sensing suspension with a concentration of 3 mg / ml;

[0075] S4: A fluorescent sensing thin film is prepared on a quartz substrate by spin coating of a fluorescent sensing suspension. The length and width of the quartz substrate can be selected as 2cm × 1cm.

[0076] like Figure 6 The image shows the change in fluorescence intensity of the coated fluorescent sensing film at its excitation wavelength of 490 nm in DCP vapor and its SEM characterization. The test method is as follows: a small amount of DCP was dropped into the bottom of a sealed quartz cell, and the fluorescent sensing film was placed in the sealed quartz cell. The change in its fluorescence emission spectrum under 490 nm excitation light over time was measured. The fluorescence of the film increased by 300% within 5 minutes in the DCP atmosphere, indicating excellent sensing performance. Compared with the 2:492 ratio synthesis in Example 2, the 5:492 ratio synthesis showed better results, and the sensing performance steadily improved with the increase of the coating ratio.

[0077] Example 4

[0078] S1: Fluorescent sensing material (i.e., the first compound);

[0079] S2: The first compound, nano zinc oxide (product name: Zinc oxide nanoparticle ink, brand: Aldrich, supplier: Sigma-Aldrich (Shanghai) Trading Co. Ltd., average particle size: 8-16nm), and 2-methylimidazole were sealed in a mass ratio of 10:162:492, heated at 110°C for one day, and then centrifuged and washed to obtain mixed material Z4;

[0080] S3: Dissolve the mixed material Z4 in the good organic solvent tetrahydrofuran to obtain a fluorescent sensing suspension with a concentration of 3 mg / ml;

[0081] S4: A fluorescent sensing thin film is prepared on a quartz substrate by spin coating of a fluorescent sensing suspension. The length and width of the quartz substrate can be selected as 2cm × 1cm.

[0082] like Figure 7 The image shows the change in fluorescence intensity of the coated fluorescent sensing film at its excitation wavelength of 490 nm in DCP vapor and its SEM characterization. The test method is as follows: a small amount of DCP is dropped into the bottom of a sealed quartz cell, and the fluorescent sensing film is placed in the sealed quartz cell. The change in its fluorescence emission spectrum under 490 nm excitation light over time is measured. The fluorescence of the film in the DCP atmosphere increases by 210% within 5 minutes, indicating excellent sensing performance.

[0083] Example 5

[0084] S1: Fluorescent sensing material (i.e., the first compound);

[0085] S2: The first compound, nano zinc oxide (product name: Zinc oxide nanoparticle ink, brand: Aldrich, supplier: Sigma-Aldrich (Shanghai) Trading Co. Ltd., average particle size: 8-16nm), and 2-methylimidazole were sealed in a mass ratio of 15:162:492, heated at 110°C for one day, and then centrifuged and washed to obtain mixed material Z5;

[0086] S3: Dissolve the mixed material Z5 in the good organic solvent tetrahydrofuran to obtain a fluorescent sensing suspension with a concentration of 3 mg / ml;

[0087] S4: A fluorescent sensing thin film is prepared on a quartz substrate by spin coating of a fluorescent sensing suspension. The length and width of the quartz substrate can be selected as 2cm × 1cm.

[0088] like Figure 8The image shows the variation of fluorescence intensity of the coated fluorescent sensing film at its excitation wavelength of 490 nm in DCP vapor and its SEM characterization. The test method is as follows: a small amount of DCP is dropped into the bottom of a sealed quartz cell, and the fluorescent sensing film is placed in the sealed quartz cell. The change of its fluorescence emission spectrum under 490 nm excitation light over time is measured, showing excellent sensing performance.

[0089] Example 6

[0090] S1: Fluorescent sensing material (i.e., the first compound);

[0091] S2: The first compound, nano zinc oxide (product name: Zinc oxide nanoparticle ink, brand: Aldrich, supplier: Sigma-Aldrich (Shanghai) Trading Co. Ltd., average particle size: 8-16nm), and 2-methylimidazole were sealed in a mass ratio of 20:162:492, heated at 110°C for one day, and then centrifuged and washed to obtain mixed material Z6;

[0092] S3: Dissolve the mixed material Z6 in the good organic solvent tetrahydrofuran to obtain a fluorescent sensing suspension with a concentration of 3 mg / ml;

[0093] S4: A fluorescent sensing thin film is prepared on a quartz substrate by spin coating of a fluorescent sensing suspension. The length and width of the quartz substrate can be selected as 2cm × 1cm.

[0094] like Figure 9 The figures show the fluorescence intensity of the coated fluorescent sensing film at its excitation wavelength of 490 nm in DCP vapor and its SEM characterization. The test method is as follows: a small amount of DCP is dropped into the bottom of a sealed quartz cell, and the fluorescent sensing film is placed in the sealed quartz cell. The change in its fluorescence emission spectrum under 490 nm excitation light over time is measured. The film exhibits the best sensing performance with a 1000% fluorescence enhancement within 5 minutes in the DCP atmosphere. However, as shown in Table 1, compared with Examples 1-6, the fluorescence quantum efficiency has stabilized and reached a relatively low value.

[0095] Table 1. Fluorescence quantum efficiency variation in Examples 1-6 of this application.

[0096] Z1 Z2 Z3 Z4 Z5 Z6 First compound Fluorescence quantum efficiency 19.72％ 12.74％ 11.16％ 9.18％ 8.81％ 9.18％ 0.76％

[0097] Note: Absolute fluorescence quantum yield (QY) was measured on a HORIBA FluoroMax-4 / Plus spectrophotometer using a calibrated integrating sphere at an excitation wavelength of 490 nm.

[0098] The above embodiments fully illustrate that the method provided in this invention, which uses a metal-organic framework structure, can make fluorescent sensing materials that do not emit light in the solid state due to the fluorescence self-aggregation quenching effect luminescent, thus enabling their application in gas phase detection. Alternatively, it can enhance the fluorescence of materials that emit weak light in the solid state due to the fluorescence self-aggregation quenching effect, thereby improving their gas phase detection efficiency.

Claims

1. A fluorescent composite material, characterized in that, The composite material comprises fluorescent materials and metal-organic frameworks (MOFs); the structural formula of the metal-organic frameworks (MOFs) is as follows: The fluorescent material is The preparation method of the fluorescent composite material includes: mixing fluorescent material, nano zinc oxide and 2-methylimidazole, sealing and reacting to obtain the fluorescent composite material.

2. The fluorescent composite material according to claim 1, characterized in that, The composite material is a fluorescent material encapsulated by metal-organic frameworks (MOFs).

3. A method for preparing the fluorescent composite material as described in claim 1, comprising: The fluorescent material, nano zinc oxide, and 2-methylimidazole are mixed, sealed, and reacted to obtain a fluorescent composite material.

4. The preparation method according to claim 3, characterized in that, The mass ratio of the fluorescent material to 2-methylimidazole is 1:492-20:492; the mass ratio of the nano zinc oxide to 2-methylimidazole is 162:492; the average particle size of the nano zinc oxide is <50nm; the reaction is carried out at a temperature of 100℃~120℃ for a reaction time of 21h~26h.

5. A fluorescent composite material thin film, characterized in that, The thin film comprises the fluorescent composite material of claim 1.

6. A method for preparing a fluorescent composite film, comprising: The fluorescent composite material described in claim 1 is dissolved in an organic solvent and then formed on a substrate to obtain a fluorescent composite film.

7. The preparation method according to claim 6, characterized in that, The organic solvent is at least one of tetrahydrofuran, dichloromethane, chloroform, toluene, and acetone; the substrate is a transparent substrate; the transparent substrate is one of a glass substrate, a quartz substrate, an organic polymer solid carrier substrate, or a composite substrate composed of ultrathin metal oxides.

8. The preparation method according to claim 6, characterized in that, The concentration of the fluorescent composite material dissolved in the organic solvent is 1 mg / ml-5 mg / ml; the film formation method is at least one of spin coating, drop coating, and dip coating.

9. A sensor, characterized in that, The sensor includes the fluorescent composite film of claim 5.

10. An application of the sensor as described in claim 9 in gas phase detection.

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