A tetraphenylethylene-based covalent organic framework material with high fluorescence quantum yield and its preparation method and use

Abstract

The present invention provides a tetraphenylethylene-based covalent organic framework material with a high fluorescence quantum yield, as well as a preparation method and uses. Due to the introduction of the aggregation-induced emission unit tetraphenylethylene, the conjugated interaction between the tetraphenylethylene moiety and the linking group is weakened, thereby changing the exciton dynamics between other linking groups, resulting in a photoluminescence quantum yield of 73%. This material exhibits excellent luminescence performance and is suitable for use in the field of optoelectronic materials, providing insights for the design of similar materials. Furthermore, this material possesses regular pores and abundant active sites. The highly reactive imine linking sites can nucleophilically attack the phosphorus-chlorine bond in the nerve agent simulant diethyl chlorophosphate, altering the conjugated relationship of its linking groups. This material exhibits excellent detection efficiency for the nerve agent simulant diethyl chlorophosphate. The material is characterized by simple and rapid operation, sensitive response, ease of use, and low cost, providing an effective technical means for relevant departments to detect potentially hazardous substances.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic materials, and in particular relates to a tetraphenylethylene-based covalent organic framework material with high fluorescence quantum yield, a preparation method and an application thereof. Background Art

[0002] Covalent organic framework (COF) materials are a class of crystalline porous materials formed by covalent cross-linking between organic monomers, with a highly ordered two-dimensional or three-dimensional network structure. Compared with other porous materials, COF not only has a large specific surface area, designable pore size and excellent thermochemical stability, but also exhibits unique fluorescence properties due to its rich structural conjugated system. By rationally designing the structure and connection mode of organic monomers, the luminescence characteristics of COF, including spectral wavelength, luminescence intensity and photostability, can be regulated, thereby giving the material fluorescence emission under specific conditions. Fluorescent COF materials are widely used in optical detection and sensing, bioimaging, information storage and anti-counterfeiting technology due to their excellent fluorescence properties. In addition, fluorescent COF materials show broad application prospects in the fields of fluorescence detection and optoelectronic devices, providing new ideas for the development and application of functional fluorescent materials.

[0003] Although fluorescent covalent organic framework (COF) materials have many advantages in the field of fluorescence applications, their current quantum yield is relatively low, which limits their further development in applications such as high-performance optoelectronics and bioimaging. This is mainly due to the structural characteristics of fluorescent COFs, including large non-radiative losses in the conjugated system and luminophore aggregation-induced quenching. In order to improve the quantum yield of fluorescent COFs, researchers are exploring a variety of strategies, including optimizing the design of organic monomers, introducing conjugated units with high fluorescence quantum yields, and functionalizing the framework structure. These methods are expected to improve the radiative transition efficiency of COFs and reduce non-radiative losses, thereby improving fluorescence performance. At present, improving quantum yield remains a key challenge in fluorescent COF research and one of the core bottlenecks in achieving widespread application of this material. Summary of the Invention

[0004] The present invention aims to address the deficiencies of the prior art by providing a tetraphenylethylene-based covalent organic framework material with a high fluorescence quantum yield, as well as its preparation method and use. By incorporating the aggregation-induced emission unit tetraphenylethylene, this material weakens the conjugated interaction between the tetraphenylethylene moiety and the linker, thereby altering the exciton dynamics between other linking groups, resulting in a photoluminescence quantum yield of 73%. This material exhibits excellent luminescence performance and is suitable for use in optoelectronic materials, providing insights for the design of similar materials. Furthermore, this material possesses regular pores and abundant active sites. The highly reactive imine linker sites can nucleophilically attack the phosphorus-chloridus bond in the nerve agent simulant diethyl chlorophosphate, altering the conjugated relationship of its linkers. This material exhibits excellent detection efficiency for the nerve agent simulant diethyl chlorophosphate. The material is characterized by simple and rapid operation, sensitive response, ease of use, and low cost, providing an effective technical means for relevant departments to detect potentially hazardous substances.

[0005] The present invention discloses a tetraphenylethylene covalent organic framework material with high fluorescence quantum yield. The unit structure of the material is a tetraphenylethylene covalent organic framework formed by the reaction of 4',4",4"',4""-(ethylene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carboxaldehyde)) and trans-1,4-cyclohexanediamine, wherein the structural formula is (I):

[0006]

[0007] The method for preparing the tetraphenylethylene-based covalent organic framework material with high fluorescence quantum yield is carried out according to the following steps:

[0008] Preparation of organic mixed solvents:

[0009] a. Mix any two of o-dichlorobenzene, 1,4-dioxane, and n-butanol, and perform ultrasonic treatment to obtain an organic mixed solvent;

[0010] b. Add 4',4",4"',4""-(ethylene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carboxaldehyde)) and trans-1,4-cyclohexanediamine into a Pyrex tube and mix, then add the mixed solution obtained in step a, and ultrasonicate for 10 seconds to 5 minutes;

[0011] c. Add acetic acid, p-toluenesulfonic acid, benzoic acid, trifluoroacetic acid or benzenesulfonic acid at a concentration of 0.5M-6M to the mixed solution obtained in step b, and continue ultrasonic treatment for 5 minutes;

[0012] d. The mixed solution obtained in step c is treated to remove dissolved gas, and liquid nitrogen is used to perform freeze-vacuum-thaw three cycles to complete degassing. In the frozen and vacuum state, the Pyrex tube is sealed with a blowtorch flame, and the reaction is carried out at a temperature of 70-140° C. for 70-168 hours. After the system returns to room temperature, the reaction is completed, and the precipitate is filtered to obtain a precipitate. The precipitate is then washed with tetrahydrofuran, dichloromethane and ethanol for 3-6 times in sequence, and vacuum dried at a temperature of 45-80° C. for 6-24 hours to obtain a tetraphenylethylene covalent organic framework material.

[0013] The invention discloses a use of the tetraphenylethylene-based covalent organic framework material with high fluorescence quantum yield in the preparation of diethyl chlorophosphate, a neurotoxin simulant for fluorescence detection.

[0014] The tetraphenylethylene covalent organic framework material is dispersed in ethanol to obtain a probe solution, and then a diethyl chlorophosphate solution is added to the probe solution. When the excitation light wavelength is 365nm, the fluorescence changes from yellow-green to orange-red.

[0015] The present invention discloses a tetraphenylethylene-based covalent organic framework material with high fluorescence quantum yield, a preparation method, and a use thereof. The material is used to detect the nerve agent simulant diethyl chlorophosphate. The specific operation is carried out according to the following steps:

[0016] Prepare detection reagents:

[0017] a. At room temperature, 0.001-0.1 g of the obtained tetraphenylethylene covalent organic framework material was weighed and dissolved in 2 mL of ethanol, and ultrasonically mixed until uniformly mixed to obtain a tetraphenylethylene covalent organic framework material detection reagent, which was packaged in a brown reagent bottle;

[0018] b. Take a 0.05M diethyl chlorophosphate solution at a volume ratio of 1:0.05 and add it to the test bottle of the detection reagent obtained in step a. Due to the protonation of the imine linker, the photoinduced electron transfer between the imine group and the tetraphenylethylene group is changed, causing the fluorescence at 543 nm to be gradually quenched and the emission wavelength to shift to longer wavelengths, thereby confirming the presence of diethyl chlorophosphate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a powder X-ray diffraction spectrum of the tetraphenylethylene covalent organic framework material prepared in Example 1 of the present invention;

[0020] Figure 2 This is a Fourier transform infrared spectrum of the tetraphenylethylene covalent organic framework material prepared in Example 1 of the present invention;

[0021] Figure 3This is the fluorescence emission change spectrum of the tetraphenylethylene covalent organic framework material prepared in Example 2 of the present invention before and after the reaction with the nerve agent simulant diethyl chlorophosphate. DETAILED DESCRIPTION

[0022] Example 1

[0023] Preparation of organic mixed solvents:

[0024] a. Mix 0.8 mL of o-dichlorobenzene and 1.2 mL of n-butanol, and ultrasonicate for 10 minutes to obtain an organic mixed solvent;

[0025] b. Add 40 mg of 4',4",4"',4""-(ethylene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carbaldehyde)) and 10 mg of trans-1,4-cyclohexanediamine into a Pyrex tube, mix well, add the mixed solution obtained in step a, and sonicate for 5 min.

[0026] c. Add 0.2 mL of 6 M acetic acid as catalyst to the mixed solution obtained in step b, and continue ultrasonic treatment for 5 minutes;

[0027] d. The mixed solution in step c was treated to remove dissolved gases, the Pyrex tube was connected to a double-row tube, and liquid nitrogen was used to perform three cycles of freezing-vacuuming-thawing to complete the degassing treatment. In the frozen and vacuum state, the Pyrex tube was sealed with a blowtorch flame, and the reaction was carried out at a temperature of 70°C for 168 hours. After the system returned to room temperature, the reaction was completed, and the precipitate was filtered to obtain a precipitate. The precipitate was then washed three times with tetrahydrofuran, dichloromethane and ethanol in sequence, and the obtained solid was vacuum dried at a temperature of 80°C for 12 hours to obtain a tetraphenylethylene covalent organic framework material.

[0028] Example 2

[0029] Preparation of organic mixed solvents:

[0030] a. Mix 0.8 mL of 1,4-dioxane and 1 mL of o-dichlorobenzene, and ultrasonicate for 10 minutes to obtain an organic mixed solvent;

[0031] b. Add 40 mg of 4',4",4"',4""-(ethylene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carbaldehyde)) and 10 mg of trans-1,4-cyclohexanediamine into a Pyrex tube, mix well, add to the mixed solution obtained in step a, and sonicate for 10 seconds.

[0032] c. Add 0.1 mL of 6 M p-toluenesulfonic acid to the mixed solution obtained in step b and continue ultrasonic treatment for 5 minutes;

[0033] d. The mixed solution in step c was treated to remove dissolved gases, the Pyrex tube was connected to a double-row tube, and liquid nitrogen was used to perform three cycles of freezing-vacuuming-thawing to complete the degassing treatment. In the frozen and vacuum state, the Pyrex tube was sealed with a blowtorch flame, and the reaction was carried out at a temperature of 80°C for 100 hours. After the system returned to room temperature, the reaction was completed, and the precipitate was filtered to obtain a precipitate. The precipitate was then washed three times with tetrahydrofuran, dichloromethane and ethanol in sequence, and the obtained solid was vacuum dried at a temperature of 70°C for 20 hours to obtain a tetraphenylethylene covalent organic framework material.

[0034] Example 3

[0035] Preparation of organic mixed solvents:

[0036] a. Mix 1 mL of 1,4-dioxane and 1 mL of n-butanol, and ultrasonicate for 10 minutes to obtain an organic mixed solvent;

[0037] b. Add 40 mg of 4',4",4"',4""-(ethylene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carbaldehyde)) and 10 mg of trans-1,4-cyclohexanediamine into a Pyrex tube, mix well, add the mixed solution obtained in step a, and sonicate for 1 min.

[0038] c. Add 0.1 mL of 6 M p-toluenesulfonic acid to the mixed solution obtained in step b, and continue ultrasonic treatment for 5 minutes;

[0039] d. The mixed solution in step c was treated to remove dissolved gas, the Pyrex tube was connected to a double-row tube, and liquid nitrogen was used to perform three cycles of freezing-vacuuming-thawing to complete the degassing treatment. In the frozen and vacuum state, the Pyrex tube was sealed with a blowtorch flame, and the reaction was carried out at a temperature of 100°C for 120 hours. After the system returned to room temperature, after the reaction was completed, the precipitate was filtered to obtain a precipitate, and the precipitate was washed three times with tetrahydrofuran, dichloromethane and ethanol in sequence. The obtained solid was vacuum dried at a temperature of 50°C for 15 hours to obtain a tetraphenylethylene covalent organic framework material.

[0040] Example 4

[0041] Preparation of organic mixed solvents:

[0042] a. Mix 0.8 mL of 1,4-dioxane and 1 mL of o-dichlorobenzene, and ultrasonicate for 10 minutes to obtain an organic mixed solvent;

[0043] b. Add 40 mg of 4',4",4"',4""-(ethylene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carbaldehyde)) and 10 mg of trans-1,4-cyclohexanediamine into a Pyrex tube, mix well, add the mixed solution obtained in step a, and sonicate for 3 minutes;

[0044] c. Add 0.1 mL of 5 M trifluoroacetic acid to the mixed solution obtained in step b, and continue ultrasonic treatment for 5 minutes;

[0045] d. The mixed solution in step c was treated to remove dissolved gases, the Pyrex tube was connected to a double-row tube, and liquid nitrogen was used to perform three cycles of freezing-vacuuming-thawing to complete the degassing treatment. In the frozen and vacuum state, the Pyrex tube was sealed with a blowtorch flame, and the reaction was carried out at a temperature of 140°C for 70 hours. After the system returned to room temperature, the reaction was completed, and the precipitate was filtered to obtain a precipitate. The precipitate was then washed with tetrahydrofuran, dichloromethane and ethanol six times in sequence. Finally, the obtained solid was vacuum dried at a temperature of 45°C for 24 hours to obtain a tetraphenylethylene covalent organic framework material.

[0046] Example 5

[0047] Preparation of organic mixed solvents:

[0048] a. Mix 0.8 mL of 1,4-dioxane and 1 mL of o-dichlorobenzene, and ultrasonicate for 10 minutes to obtain an organic mixed solvent;

[0049] b. Add 40 mg of 4',4",4"',4""-(ethylene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carbaldehyde)) and 10 mg of trans-1,4-cyclohexanediamine into a Pyrex tube, mix well, add the mixed solution obtained in step a, and sonicate for 4 minutes;

[0050] c. Add 0.1 mL of 5 M benzoic acid as catalyst to the mixed solution obtained in step b, and continue ultrasonic treatment for 5 minutes;

[0051] d. The mixed solution in step c was treated to remove dissolved gases, the Pyrex tube was connected to a double-row tube, and liquid nitrogen was used to perform three cycles of freezing-vacuuming-thawing to complete the degassing treatment. In the frozen and vacuum state, the Pyrex tube was sealed with a blowtorch flame, and the reaction was carried out at a temperature of 120°C for 130 hours. After the system returned to room temperature, the reaction was completed, and the precipitate was filtered to obtain a precipitate. The precipitate was then washed four times with tetrahydrofuran, dichloromethane and ethanol in sequence, and the obtained solid was vacuum dried at a temperature of 60°C for 10 hours to obtain a tetraphenylethylene covalent organic framework material.

[0052] Example 6

[0053] The crystal structure of any of the tetraphenylethylene covalent organic framework materials obtained in Examples 1-5 was determined using an X-ray crystal diffractometer. Figure 1 As shown, it can be seen that the tetraphenylethylene-based covalent organic framework material has an ordered crystal structure;

[0054] The chemical structure of any tetraphenylethylene covalent organic framework material obtained in Examples 1-5 was determined using an infrared spectrometer. Figure 2 As shown in the figure, the characteristic peak of the monomer of the preparation raw material of tetraphenylethylene covalent organic framework material disappears, and the peak at 1640 cm -1 The characteristic peak corresponding to the imine bond (-C=N-) appears at , proving that the organic monomer 4',4",4"',4""-(ethylene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carboxaldehyde)) and the organic monomer trans-1,4-cyclohexanediamine in the tetraphenylethylene covalent organic framework material are connected by chemical bonds.

[0055] Example 7

[0056] Any one of the tetraphenylethylene covalent organic framework materials obtained in Examples 1-5 was used to detect the nerve agent simulant diethyl chlorophosphate. The specific operation was carried out according to the following steps:

[0057] Prepare detection reagents:

[0058] a. At room temperature, 0.01 g of the obtained tetraphenylethylene covalent organic framework material was weighed and dissolved in 2 mL of ethanol, and ultrasonically mixed to obtain a tetraphenylethylene covalent organic framework material detection reagent, which was packaged in a brown reagent bottle;

[0059] b Take 0.05M diethyl chlorophosphate solution, by volume ratio of 1: 0.05, was added to the test bottle containing the detection reagent obtained in step a, causing the fluorescence at 543nm to be gradually quenched, and the emission wavelength shifted to a longer wavelength, in order to determine the presence of diethyl chlorophosphate;

[0060] The fluorescence response of tetraphenylethylene covalent organic framework materials to nerve agent simulants was measured using a fluorescence spectrometer. Figure 3 As shown, the fluorescence peak intensity weakened and red-shifted to a longer wavelength, thereby confirming the presence of diethyl chlorophosphate.

Claims

1. A tetraphenylethylene-based covalent organic framework material with high fluorescence quantum yield, characterized in that The unit structure of the material is a tetraphenylethylene covalent organic framework formed by the Schiff base reaction of 4',4",4"',4""-(ethylene-1,1,2,2-tetrayl)tetrakis([1,1'-biphenyl]-4-carboxaldehyde) and trans-1,4-cyclohexanediamine, wherein the structural formula is (I):

2. The method for preparing a tetraphenylethylene-based covalent organic framework material with high fluorescence quantum yield according to claim 1, characterized in that: Follow these steps: Preparation of organic mixed solvents: a. Mix any two of o-dichlorobenzene, 1,4-dioxane, and n-butanol, and perform ultrasonic treatment to obtain an organic mixed solvent; b. Add 4',4",4"',4""-(ethylene-1,1,2,2-tetrayl)tetrakis([1,1'-biphenyl]-4-carbaldehyde) and trans-1,4-cyclohexanediamine into a Pyrex tube and mix, then add the mixed solution obtained in step a, and ultrasonicate for 10 seconds to 5 minutes; c. Add acetic acid, p-toluenesulfonic acid, benzoic acid, trifluoroacetic acid or benzenesulfonic acid at a concentration of 0.5M-6M to the mixed solution obtained in step b, and continue ultrasonic treatment for 5 minutes; d. The mixed solution obtained in step c is treated to remove dissolved gas, and liquid nitrogen is used to perform freeze-vacuum-thaw three cycles to complete degassing. In the frozen and vacuum state, the Pyrex tube is sealed with a blowtorch flame, and the reaction is carried out at a temperature of 70-140° C. for 70-168 hours. After the system returns to room temperature, the reaction is completed, and the precipitate is filtered to obtain a precipitate. The precipitate is then washed with tetrahydrofuran, dichloromethane and ethanol for 3-6 times in sequence, and vacuum dried at a temperature of 45-80° C. for 6-24 hours to obtain a tetraphenylethylene covalent organic framework material.

3. Use of the tetraphenylethylene-based covalent organic framework material with high fluorescence quantum yield as claimed in claim 1 in the preparation of diethyl chlorophosphate for fluorescence detection of nerve agent simulant.

4. The use according to claim 3, characterized in that The tetraphenylethylene covalent organic framework material is dispersed in ethanol to obtain a probe solution, and then a diethyl chlorophosphate solution is added to the probe solution. When the excitation light wavelength is 365nm, the fluorescence changes from yellow-green to orange-red.

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