A rapidly synthesized COFs material and its application in detecting the water content in organic solvents

Abstract

The present invention discloses a rapidly synthesized COFs material and its application in detecting the water content in organic solvents, belonging to the fields of covalent organic framework materials and analytical detection. In the present invention, 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxybenzene-1,4-dicarbaldehyde are used as raw materials, and TAPB-DMTP-COF is rapidly synthesized by the grinding method. The specific steps are as follows: p-toluenesulfonic acid and 1,3,5-tris(4-aminophenyl)benzene are fully mixed; then 2,5-dimethoxybenzene-1,4-dicarbaldehyde is added, and the mixture is fully ground and heated; the obtained dark red powder is immersed in hot water, and the initial product is collected by filtration; it is washed 3 times with tetrahydrofuran and acetone respectively, and then centrifugally washed 5 times with absolute ethanol; the solid product is collected and vacuum dried in an oven to obtain a red powder TAPB-DMTP-COF. By controlling the pH value of the suspension, the originally non-luminescent TAPB-DMTP-COF emits blue-violet fluorescence, realizing the analysis and detection of the H2O content in the solvent; the method of the present invention is simple and rapid, can be detected by naked eye observation without using large instruments, and has good application potential.

Description

Technical Field

[0001] The present invention belongs to the fields of covalent organic framework materials and analytical detection, and specifically relates to a rapidly synthesized COFs material and its application in detecting the water content in organic solvents. Background Technique

[0002] Covalent organic framework materials (COFs) are a new type of porous crystalline polymer, which are composed of light elements (such as B, C, Si, N, and O) connected by strong covalent bonds (such as B-O, C-N, C=N, and C=C-N) to form organic units. They are constructed by dynamic reversible covalent chemistry and can precisely integrate organic units into periodic columnar π arrays and ordered pores. Due to the characteristics of low density, high stability, large surface area, and inherent porosity of COFs materials, they have been increasingly used as fluorescence sensors in recent years, and exhibit characteristics such as high physical and chemical stability, fast response time, and high detection sensitivity in applications.

[0003] However, it is difficult to obtain COFs materials with strong fluorescence. Fluorescent COFs materials will undergo fluorescence quenching due to bond rotation and π-π accumulation, so the quantum yield of COFs materials is not high. For this reason, on the one hand, researchers use non-planar monomers with aggregation-induced emission to construct COFs to enhance fluorescence. On the other hand, the prepared COFs materials are divided into two-dimensional nanosheets to reduce fluorescence quenching caused by polymerization. For example, Jin et al. reported the design and synthesis of sp 2 carbon conjugated frameworks. The C=C double bonds connect pyrene and vinylidene linkers into a 2D sp 2 carbon lattice in the topological structure. These carbon lattices are designed to conduct π conjugation along the x and y directions and form a layered structure, so stronger fluorescence emission can be generated after being exfoliated into nanosheets. COFs materials can replicate multiple identical binding sites through the entire extended framework, so signals can be effectively conducted and amplified through the framework to achieve ultra-high sensitivity in detection. Therefore, in the research, considering external auxiliary means to regulate the luminescence properties of COFs materials, reduce fluorescence quenching caused by π-π accumulation, enhance the fluorescence intensity of COFs materials, improve the sensitivity of the method, and expand the application scope of fluorescence sensing detection of COFs materials is the key to the research. In addition, the most commonly used synthesis method for COFs materials at present is the solvothermal synthesis method. Using this method will inevitably have disadvantages such as cumbersome operation, long time consumption, and residual toxic solvents. Therefore, there is a great need to explore a simple, economical, and environmentally friendly synthesis method.

[0004] Water is one of the most important and essential substances in human daily life and chemical research. At the same time, it is also an important impurity that needs to be removed for many chemical and industrial production processes. For many sensitive chemical reactions, water controls the yield and selectivity of the final product. Although traditional analytical techniques for detecting trace water, such as Karl Fischer titration and chromatography, can achieve water detection in parts per million, they have some disadvantages, such as the use of toxic reagents, long analysis time, and cumbersome operation. Therefore, simple, efficient, and convenient methods are needed to estimate the water content in routine laboratory work such as organic synthesis, solvent purification, liquid chromatography, and industrial processes. Recently, luminescence-based sensors have been developed to detect water using different kinds of fluorescent probes, especially to detect moisture in organic solvents and food raw materials. However, these systems have disadvantages such as fluorescence shut-off, low sensitivity, slow response time, emission signal collection efficiency, and uneven probe distribution, which limit the detection of water content in the system. COFs have the advantages of high crystallinity, good stability, controllable structure, and high porosity, making them potential candidates for water detection applications. Summary of the invention

[0005] In order to overcome the technical problems existing in the background technology, the present invention proposes a rapidly synthesized COFs material and its application in detecting the water content in an organic solvent. TAPB-DMTP-COF is rapidly synthesized by a grinding method, which greatly shortens its synthesis time. By controlling the pH value of the suspension, the originally non-luminescent TAPB-DMTP-COF emits blue-purple fluorescence, thereby realizing the analytical detection of the H2O content in the solvent. The method of the present invention is simple and rapid, and can be detected by naked eye observation without using large instruments, and has good application potential.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A rapidly synthesized COFs material is TAPB-DMTP-COF, which is synthesized by a grinding method using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde as raw materials.

[0008] The specific steps are as follows:

[0009] 1) fully mixing p-toluenesulfonic acid and 1,3,5-tris(4-aminophenyl)benzene;

[0010] 2) adding 2,5-dimethoxybenzene-1,4-dicarbaldehyde to the mixture in step 1), grinding thoroughly, and then heating;

[0011] 3) soaking the dark red powder obtained in step 2) in hot water, and collecting the initial product by filtration;

[0012] 4) Filter the crude product, wash it three times with tetrahydrofuran and acetone respectively, and then wash it five times by centrifugation with absolute ethanol.

[0013] 5) Collect the solid product from step 4), place it in an oven for vacuum drying to obtain the red powder TAPB-DMTP-COF.

[0014] Further, in step 1), the amount of p-toluenesulfonic acid used is 1.0 - 3.0 mmol, and the amount of 1,3,5-tris(4-aminophenyl) used is 0.2251 - 0.6753 mmol.

[0015] Further, the amount of 2,5-dimethoxybenzene-1,4-dicarbaldehyde used is 0.45 - 1.35 mmol, the grinding time range is 25 - 30 min, and the heating temperature is 180 °C.

[0016] Further, in step 3), the time for hot water soaking is 5 - 15 min.

[0017] Application of a rapidly synthesized COFs material as described above in detecting the water content in organic solvents. The specific method steps are as follows:

[0018] 1) Through pH regulation, convert non-fluorescent TAPB-DMTP-COF into fluorescent TAPB-DMTP-COF. The specific operation is as follows: Take the solid powder of TAPB-DMTP-COF and disperse it in anhydrous methanol, stir for 30 min; adjust the pH value to 4.0 with 0.1 M HCl and continue stirring for 1.5 h to obtain a TAPB-DMTP-COF suspension with a concentration of 2.0 mg / mL.

[0019] 2) Take 50.0 μL of the suspension and place it in multiple 1.5 mL centrifuge tubes, add the solution to be detected, and then make up the volume to 1 mL with methanol. After thorough mixing, detect the maximum fluorescence emission peak.

[0020] Advantages of the present invention: The present invention uses the grinding method to rapidly synthesize TAPB-DMTP-COF, greatly shortening its synthesis time. By controlling the pH value of the suspension, the originally non-luminescent TAPB-DMTP-COF emits blue-violet fluorescence, realizing the analysis and detection of the H2O content in the solvent. The method of the present invention is simple and fast, and can be detected by naked eye observation without using large instruments, having good application potential. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the synthesis of TAPB-DMTP-COF in Example 1;

[0022] Figure 2 It is the PXRD pattern of TAPB-DMTP-COF in Example 1;

[0023] Figure 3 The refinement result and structural diagram of TAPB-DMTP-COF in Example 1;

[0024] Figure 4 This is the fluorescence emission spectrum of TAPB-DMTP-COF after pH adjustment in Example 1;

[0025] Figure 5 This is the result of the effect of different contents of H2O on the fluorescence of TAPB-DMTP-COF. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0027] Example 1

[0028] A method for preparing a rapidly synthesized COFs material, the specific steps are as follows:

[0029] 1) P-toluenesulfonic acid (0.1902 g, 1.0 mmol) and 1,3,5-tris(4-aminophenyl)benzene (TAPB) (0.0791 g, 0.2251 mmol) were thoroughly mixed;

[0030] 2) Add 2,5-dimethoxybenzene-1,4-dicarbaldehyde (DMTP) (0.0874 g, 0.45 mmol) to the mixture in step 1), grind thoroughly for 25 minutes, and then heat at 180° C. for 15 minutes;

[0031] 3) soaking the dark red powder obtained in step 2) in hot water for 5 minutes, and collecting the initial product by filtration;

[0032] 4) Filter the initial product, wash it with tetrahydrofuran and acetone 3 times each, and then wash it with anhydrous ethanol by centrifugation 5 times;

[0033] 5) Collect the solid product of step 4), place it in an oven at 80° C. and vacuum dry it to obtain red powder TAPB-DMTP-COF.

[0034] The schematic diagram of the synthesis of TAPB-DMTP-COF is shown in Figure 1 The PXRD pattern of the synthesized TAPB-DMTP-COF is shown in Figure 2, where the abscissa represents the 2θ diffraction angle; the strong diffraction peak of the PXRD pattern of the TAPB-DMTP-COF material at 2.819° can be attributed to the (100) crystal plane. In addition, the five weaker signal peaks at 4.859°, 5.599°, 7.359°, 9.699° and 25.258° can be respectively corresponding to the (110), (200), (120), (130) and (001) crystal planes after analysis.

[0035] The results of the simulation of the structure of the synthesized TAPB-DMTP-COF in this example by Materials Studio (MS) software are shown in Figure 3

(A) The PXRD spectrum of the experimentally obtained TAPB-DMTP-COF, the PXRD spectrum of the MS simulation based on the AA-stacking model, and the PXRD spectrum of the MS simulation based on the AB-stacking model; (B) Schematic diagrams of the AA-stacking and AB-stacking structures of TAPB-DMTP-COF; (C) Pawley refinement results of TAPB-DMTP-COF; (D) Schematic diagram of the refined structure of TAPB-DMTP-COF

[0036] The TAPB-DMTP-COF material as described above is applied to the detection of the water content in organic solvents, and the specific method steps are as follows:

[0037] 1) Through pH regulation, the non-fluorescent TAPB-DMTP-COF is regulated to the fluorescent TAPB-DMTP-COF. The specific operation is as follows: Take 60.0 mg of TAPB-DMTP-COF solid powder and disperse it in 30.0 mL of anhydrous methanol, and stir for 30 min; adjust the pH value to 4.0 with 0.1 M HCl and continue to stir for 1.5 h to obtain a TAPB-DMTP-COF suspension with a concentration of 2.0 mg / mL;

[0038] The fluorescence emission spectrum diagram of the synthesized TAPB-DMTP-COF suspension is shown in Figure 4, where the abscissa represents the wavelength and the ordinate represents the fluorescence intensity; its maximum emission wavelength is 433 nm; the synthesized TAPB-DMTP-COF is light yellow under natural light and blue-violet under a 365 nm ultraviolet lamp.

[0039] 2) Take 50.0 μL of the suspension and place it in multiple 1.5 mL centrifuge tubes. Add the solution to be detected, and then make up the volume to 1 mL with methanol. After thorough mixing, detect the maximum emission peak of fluorescence.

[0040] Example 2

[0041] A preparation method of a rapidly synthesized COFs material, the specific steps are as follows:

[0042] 1) Thoroughly mix p-toluenesulfonic acid (0.3804 g, 2.0 mmol) and 1,3,5-tris(4-aminophenyl)benzene (TAPB) (0.1582 g, 0.4502 mmol);

[0043] 2) Add 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP) (0.1748 g, 0.90 mmol) to the mixture in step 1), grind thoroughly for 28 minutes, and then heat at 180 °C for 15 minutes;

[0044] 3) Immerse the dark red powder obtained in step 2) in hot water for 10 minutes, and collect the crude product by filtration;

[0045] 4) Filter the crude product, wash it 3 times with tetrahydrofuran and acetone respectively, and then wash it 5 times by centrifugation with anhydrous ethanol;

[0046] 5) Collect the solid product in step 4), place it in an oven at 80 °C for vacuum drying to obtain the red powder TAPB-DMTP-COF.

[0047] Example 3

[0048] A preparation method of a rapidly synthesized COFs material, the specific steps are as follows:

[0049] 1) Thoroughly mix p-toluenesulfonic acid (0.5760 g, 3.0 mmol) and 1,3,5-tris(4-aminophenyl)benzene (TAPB) (0.2373 g, 0.6753 mmol);

[0050] 2) Add 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP) (0.2622 g, 1.35 mmol) to the mixture in step 1), grind thoroughly for 30 minutes, and then heat at 180 °C for 15 minutes;

[0051] 3) Immerse the dark red powder obtained in step 2) in hot water for 15 minutes, and collect the crude product by filtration;

[0052] 4) Filter the crude product, wash it 3 times with tetrahydrofuran and acetone respectively, and then centrifuge and wash it 5 times with absolute ethanol.

[0053] 5) Collect the solid product from step 4), place it in an oven at 80 °C for vacuum drying to obtain the red powder TAPB-DMTP-COF.

[0054] Experimental analysis

[0055] Take the TAPB-DMTP-COF suspension after pH regulation in Example 1, add a series of different volumes of ultrapure water, make up the volume to 1.0 mL with methanol, mix well and measure the change in fluorescence emission spectrum.

[0056] The result of the red shift of the fluorescence emission of TAPB-DMTP-COF caused by H2O is shown in Figure 5 , where the abscissa represents the wavelength and the ordinate represents the fluorescence intensity. From Figure 5 it can be seen that H2O can cause a red shift in the maximum emission peak of the fluorescence of TAPB-DMTP-COF.

[0057] The present invention uses the grinding method to rapidly synthesize TAPB-DMTP-COF, greatly shortening its synthesis time, and by controlling the pH value of the suspension, making the originally non-luminescent TAPB-DMTP-COF emit blue-violet fluorescence, realizing the analysis and detection of the H2O content in the solvent; the method of the present invention is simple and fast, can be detected by naked eye observation without using large instruments, and has good application potential.

[0058] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. Application of a rapidly synthesized COFs material in detecting water content in organic solvents, characterized in that: The rapidly synthesized COFs material is TAPB-DMTP-COF, which is synthesized by a grinding method using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde as raw materials. The specific preparation steps are as follows: 1) Thoroughly mix p-toluenesulfonic acid and 1,3,5-tris(4-aminophenyl)benzene; 2) Add 2,5-dimethoxybenzene-1,4-dicarbaldehyde to the mixture in step 1), grind thoroughly, and then heat; 3) soaking the dark red powder obtained in step 2) in hot water, and collecting the initial product by filtration; 4) Filter the initial product, wash it with tetrahydrofuran and acetone for 3 times respectively, and then wash it with anhydrous ethanol by centrifugation for 5 times; 5) Collecting the solid product of step 4) and drying it in a vacuum oven to obtain red powder TAPB-DMTP-COF; The specific method steps of the application of the rapidly synthesized COFs material in detecting the water content in an organic solvent are as follows: 1) The non-fluorescent TAPB-DMTP-COF was adjusted to fluorescent TAPB-DMTP-COF by pH control. The specific operation was as follows: TAPB-DMTP-COF solid powder was dispersed in anhydrous methanol and stirred for 30 min; the pH value was adjusted to 4.0 with 0.1 M HCl and stirred for 1.5 h to obtain a TAPB-DMTP-COF suspension with a concentration of 2.0 mg / mL; 2) Take 50.0 μL of the suspension and place it in multiple 1.5 mL centrifuge tubes, add the solution to be tested, and then dilute to 1 mL with methanol. After thorough mixing, detect the maximum fluorescence emission peak.

2. Use of a rapidly synthesized COF material according to claim 1 in detecting the water content in organic solvents, characterized in that: In the COFs material preparation step 1), the amount of p-toluenesulfonic acid used is 1.0-3.0 mmol, and the amount of 1,3,5-tris(4-aminophenyl) used is 0.2251-0.6753 mmol.

3. Use of a rapidly synthesized COF material according to claim 1 in detecting the water content in organic solvents, characterized in that: In the COFs material preparation step 2), the amount of 2,5-dimethoxybenzene-1,4-dicarbaldehyde used is 0.45-1.35 mmol, the grinding time ranges from 25-30 min, and the heating temperature is 180°C.

4. Use of a rapidly synthesized COF material according to claim 1 in detecting the water content in organic solvents, characterized in that: In the COFs material preparation step 3), the hot water immersion time is 5-15 minutes.

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