A COF material with controllable morphology, its preparation method and application

Abstract

The present invention discloses a COFs material with controllable morphology, its preparation method and application, belonging to the fields of covalent organic framework materials and analytical detection. In the present invention, the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TTA) and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene (TFP) are selected as raw materials, and different morphologies of TTA-TFP-COF materials are prepared by a solvothermal method, a room-temperature solvent method, a room-temperature solvent method + benzaldehyde and aniline, realizing precise control of the morphology of the TTA-TFP-COF materials. Based on the particle changes of the synthesized materials, their scattering properties are used for analysis and detection. When there are Fe 3+ and Cr 3+ ions in the aqueous solution, the scattering peak intensity of TTA-TFP-COF can be greatly weakened, and rapid detection of Fe 3+ and Cr 3+ ions in the aqueous solution can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of covalent organic framework materials, and more specifically, relates to a COFs material with controllable morphology, a preparation method thereof, and applications thereof. Background Art

[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. Compared with traditional materials, COFs materials have some unique properties, such as large surface area, pre-designed pore geometry, excellent crystallinity, inherent adaptability, and high flexibility in structure and function design. Therefore, the scope of properties of COFs materials has been rapidly extended to include numerous applications from energy to the environment.

[0003] So far, COFs microcrystals have various shapes, such as ribbon-like, fibrous, flaky, cubic, rod-like, spherical, and other morphologies. However, the current research still knows little about the formation and self-assembly mechanism of COFs microcrystals. In fact, the growth of 2D COFs is very fast, and the product almost immediately precipitates, resulting in kinetic traps and inhibiting the formation of highly crystalline structures, let alone achieving precise morphology control. Therefore, slowing down the reaction process is an effective method currently proposed to form higher crystallinity and control the morphology of COFs materials.

[0004] Since controllable morphology has a great impact on the optical properties of materials, especially scattering properties. For example, the light scattering of nanoparticles has a long history. More specifically, good development has been achieved in the light scattering of nanoparticles. For example, the light scattering determination of drugs, DNA, proteins, and heavy metals such as mercury, cadmium, lead, chromium, and arsenic in the aqueous environment has achieved good development. As a typical nanomaterial, if the growth of the morphology of COFs materials can be precisely controlled, it will have great application prospects for studying its light scattering properties, and there is currently no report on applying the scattering properties of COFs to analytical detection.

[0005] In the prior art, the synthesized COFs materials are mostly irregularly shaped blocks, which limits their scope of application. At the same time, COFs materials are difficult to reshape because they are insoluble in various solvents and cannot be melted at high temperatures. Therefore, it is a difficult problem to prepare COFs materials with regular shapes. Moreover, the application of covalent organic frameworks in analytical detection is mostly limited to their fluorescence properties, and there are almost no reports on the scattering properties based on their ordered structures in environmental analysis. Summary of the Invention

[0006] To overcome the technical problems existing in the background art, the present invention proposes a COFs material with controllable morphology, its preparation method and application. Using 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TTA) and 1,3,5-tris(4-formylphenyl)-benzene (TFP) as raw materials, different preparation methods are used to precisely control the morphology of the synthesized TTA-TFP-COF material, and using the scattering properties of the synthesized TTA-TFP-COF material, it is applied to the rapid detection of Fe 3+ and Cr 3+ metal ions.

[0007] To achieve the above object, the present invention is realized by the following technical solutions:

[0008] A COFs material with controllable morphology, the raw materials for preparation are the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TTA) and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene (TFP).

[0009] One of the preparation methods, the specific steps are as follows:

[0010] 1) Add the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene into a 10 mL Pyrex tube, then add methanol and acetic acid and shake evenly, and ultrasonically treat for 10.0 min until the monomers are completely dispersed;

[0011] 2) Immerse the Pyrex tube in step 1) into liquid nitrogen and quickly freeze it, evacuate and seal it, and then place it in an oven at 40 - 120 °C for reaction for 2 - 4 d to obtain the TTA-TFP-COF crude product;

[0012] 3) Filter the TTA-TFP-COF crude product in step 2), wash it successively with anhydrous N,N-dimethylformamide and tetrahydrofuran, and then wash it by centrifugation with anhydrous ethanol;

[0013] 4) Collect the solid product in step 3), place it in an oven at 60 - 100 °C for drying to obtain yellow powder TTA-TFP-COF, and its morphology is an irregular granular structure.

[0014] Preferably, the molar ratio of the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine to the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene is 1:1, the amount of methanol used is 3.0 mL, and the amount of acetic acid used is 0.2 - 0.6 mL.

[0015] The second preparation method is as follows:

[0016] 1) Add the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene into a 10 mL centrifuge tube, then add acetonitrile and acetic acid, shake well, and ultrasonically treat for 10.0 min until the monomers are completely dispersed;

[0017] 2) React the centrifuge tube in step 1) at room temperature for 1 - 6 days to obtain the crude product of TTA-TFP-COF;

[0018] 3) Filter the crude product of TTA-TFP-COF in step 2), wash it successively with anhydrous N,N-dimethylformamide and tetrahydrofuran, and then wash it by centrifugation with anhydrous ethanol;

[0019] 4) Collect the solid product in step 3), dry it in an oven at 60 - 100 °C to obtain the yellow powder TTA-TFP-COF, and its morphology is a regular hollow tube structure.

[0020] The third preparation method is as follows:

[0021] 1) Add the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene into a 10 mL centrifuge tube, add acetonitrile and shake well, then add benzaldehyde and aniline respectively, shake well, and then add acetic acid, shake well and ultrasonically treat for 10.0 min until the monomers are completely dispersed;

[0022] 2) React the centrifuge tube in step 1) at room temperature for 1 - 6 days to obtain the crude product of TTA-TFP-COF;

[0023] 3) Filter the crude product of TTA-TFP-COF in step 2), wash it successively with anhydrous N,N-dimethylformamide and tetrahydrofuran, and then wash it by centrifugation with anhydrous ethanol;

[0024] 4) Collect the solid product in step 3), dry it in an oven at 60 - 100 °C to obtain the yellow powder TTA-TFP-COF, and its morphology is a flower-like structure.

[0025] Preferably, in Preparation Method 2 or 3, the molar ratio of the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene is 1:1, the amount of acetonitrile used is 5.0 mL, and the amount of acetic acid used is 0.3 - 1.2 mL.

[0026] The COF material with a hollow tube structure prepared by the foregoing method can be applied to the detection of Fe 3+ and Cr 3+ metal ions. The specific method steps are as follows:

[0027] 1) Weigh the hollow tubular TTA-TFP-COF powder and disperse it in absolute ethanol to prepare a suspension of TTA-TFP-COF.

[0028] 2) Take 20 μL of the suspension and place it in a 1.5 mL centrifuge tube, add a solution containing Fe 3+ and Cr 3+ and add water to make up to 1 mL. After shaking for 10 s, let it stand for 20 min.

[0029] 3) Detect the scattering intensity of the mixture obtained in step 2).

[0030] Advantages of the present invention:

[0031] (1) Using 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TTA) and 1,3,5-tris(4-formylphenyl)-benzene (TFP) as raw materials, the present invention can achieve precise control of the morphology of the TTA-TFP-COF material by using different preparation methods.

[0032] (2) The TTA-TFP-COF material with a hollow tube structure morphology prepared by the present invention can be applied to the rapid detection of Fe 3+ and Cr 3+ metal ions in aqueous solution. Description of the Drawings

[0033] Figure 1 is a schematic diagram of the synthesis of TTA-TFP-COF;

[0034] Figure 2 is the PXRD pattern of the TTA-TFP-COF synthesized in Example 1;

[0035] Figure 3 is the PXRD pattern and structural schematic diagram of the stacking model of the TTA-TFP-COF in Example 1;

[0036] Figure 4 is the XRD pattern of the TTA-TFP-COF synthesized in Example 1 and Example 2;

[0037] Figure 5 XRD pattern of the TTA-TFP-COF synthesized in Example 3;

[0038] Figure 6 TEM image of the TTA-TFP-COF synthesized in Example 1;

[0039] Figure 7 SEM image of the TTA-TFP-COF synthesized in Example 1;

[0040] Figure 8 TEM images of the TTA-TFP-COF synthesized by the method of Example 2 under different acetic acid dosages;

[0041] Figure 9 SEM images of the TTA-TFP-COF synthesized by the method of Example 2 under different acetic acid dosages;

[0042] Figure 10 TEM images of the TTA-TFP-COF synthesized in Example 3 at room temperature;

[0043] Figure 11 SEM images of the TTA-TFP-COF synthesized in Example 3;

[0044] Figure 12 Schematic diagram of the influence of different metal ions on the scattering of TTA-TFP-COF;

[0045] Figure 13 For different concentrations of Fe 3+ , Cr 3+ Ion weakening the linear relationship diagram of the scattering of TTA-TFP-COF. Detailed implementation manners

[0046] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited to the content described.

[0047] Example 1

[0048] The preparation method steps of a COFs material with an irregular granular structure are as follows:

[0049] 1) Add the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (21.26 m, 0.60 mmol) and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene (23.43 mg, 0.60 mmol) into a 10 mL Pyrex tube, then add 3.0 mL of methanol and 0.2 mL of 6 M acetic acid, shake evenly, and ultrasonically treat for 10.0 min until the monomers are completely dispersed;

[0050] 2) In step 1), the Pyrex tube was immersed in liquid nitrogen and rapidly frozen. After being evacuated and sealed, it was placed in an 80 °C oven and reacted for 3 days to obtain the TTA-TFP-COF crude product;

[0051] 3) The TTA-TFP-COF crude product obtained in step 2) was filtered, washed 3 times each with anhydrous N,N-dimethylformamide and tetrahydrofuran in sequence, and then centrifugally washed 5 times with anhydrous ethanol;

[0052] 4) The solid product obtained in step 3) was collected, dried in a 100 °C oven to obtain the yellow powder TTA-TFP-COF.

[0053] The synthesis schematic diagram of TTA-TFP-COF in this example is shown in Figure 1 , and the PXRD pattern of the synthesized TTA-TFP-COF is shown in Figure 2 , where the abscissa represents the 2θ diffraction angle; the PXRD pattern of the TTA-TFP-COF material shows a strong diffraction peak at approximately 4.077°, which can be attributed to the reflection plane (100). In addition, there are five weak diffraction peaks at 7.019°, 8.073°, 10.717°, 14.554° and 24.518° corresponding to the (110), (200), (210), (130) and (001) crystal planes respectively.

[0054] The results of simulating the structure of the TTA-TFP-COF synthesized in this example by MaterialsStudio (MS) software are shown in Figure 3 , Figure 3 In A, they are respectively the PXRD spectrum of the experimentally obtained TTA-TFP-COF, the PXRD simulated by MS based on the AA-stacking model, the PXRD simulated by MS based on the AB-stacking model, and the PXRD simulated by MS based on the ABC-stacking model; Figure 3 B is the schematic diagram of the structure of TTA-TFP-COF; Figure 3 C is the Pawley refinement result of TTA-TFP-COF; Figure 3 D is the schematic diagram of the structure of the refined TTA-TFP-COF. The initial unit cell parameters are α = 90°, β = 90°, γ = 120°. The structure stacking mode of TTA-TFP-COF is the AA-stacking model structure, and its space group is P6. After correcting the unit cell parameters of TTA-TFP-COF using Pawley refinement, the weighted R factors obtained are: Rwp = 6.665%, Rp = 4.113%. From the refined structure diagram, the theoretical pore size of TTA-TFP-COF is The layer spacing is

[0055] The morphology of the TTA-TFP-COF synthesized in this example is shown in Figure 6 and Figure 7 , which is an irregular granular structure.

[0056] Example 2

[0057] The preparation method of a COFs material with a regular hollow tube structure morphology is as follows:

[0058] 1) Add the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (21.26 mg, 0.60 mmol) and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene (23.43 mg, 0.60 mmol) into a 10 mL centrifuge tube, then add 5.0 mL of acetonitrile and 12 M acetic acid, shake evenly, and ultrasonically treat for 10.0 min until the monomers are completely dispersed;

[0059] 2) React the centrifuge tube in step 1) at room temperature for 3 days to obtain the TTA-TFP-COF crude product;

[0060] 3) Filter the TTA-TFP-COF crude product in step 2), wash it 3 times with anhydrous N,N-dimethylformamide and tetrahydrofuran in sequence, and then centrifuge and wash it 5 times with anhydrous ethanol;

[0061] 4) Collect the solid product in step 3), place it in an oven at 100 °C for drying to obtain the yellow powder TTA-TFP-COF.

[0062] The synthesis schematic diagram of the TTA-TFP-COF in this example is shown in Figure 1 , and the PXRD pattern of the synthesized TTA-TFP-COF is shown in Figure 4 , where the abscissa represents the 2θ diffraction angle and the ordinate represents the diffraction intensity.

[0063] The morphology of the TTA-TFP-COF synthesized in this example is shown in Figure 8 and Figure 9 , which is a hollow tube with a rough surface. For the TTA-TFP-COF synthesized in Figures A, B, and C, the amount of acetic acid used is 0.3 mL; for Figures D, E, and F, the amount of acetic acid used is 0.5 mL; for Figures G, H, and I, the amount of acetic acid used is 0.7 mL. As the amount of acetic acid added increases, the diameter of the hollow tube increases significantly.

[0064] Using the TTA-TFP-COF synthesized in this example to achieve Fe in aqueous solution 3+ 、Cr 3+Detection of metal ions. The specific steps are as follows: Weigh the solid powder of TTA-TFP-CO and disperse it in absolute ethanol to prepare a TTA-TFP-COF suspension with a concentration of 0.02 mg / mL. Take 20.0 μL and put it into a 1.5 mL centrifuge tube, and then add a series of ion solutions of different concentrations of Fe 3+ and Cr 3+ respectively. Finally, add water to make the volume up to 1.0 mL. Shake well. After reacting for 25.0 min, detect the change in its scattering intensity.

[0065] Figure 12 Shows the influence of different metal ions on the scattering intensity of TTA-TFP-COF. As Figure 12 shown, after various metal ions (including Hg 2+ , Fe 3+ , Cr 3+ , Mn 2+ , Co 2+ , Ni 2+ , Cd 2+ , Ca 2+ , Na + , Mg 2+ , Zn 2+ , Pb 2+ and Cu 2+ ) act on TTA-TFP-COF, only Fe 3+ and Cr 3+ ions can greatly weaken its scattering, while there is no obvious change in the scattering signal in the presence of other cations. It is proved that TTA-TFP-COF has good selectivity for Fe 3+ and Cr 3+ ions.

[0066] In this example, the scattering intensity of Fe 3+ and Cr 3+ ions weakening TTA-TFP-COF is as Figure 13 shown, where the abscissa represents the metal ions and the ordinate represents the decrease value of the scattering intensity. Under the optimal detection conditions, a series of ion solutions of different concentrations of Fe 3+ are added to the TTA-TFP-COF ethanol suspension, and its scattering intensity is as Figure 13 A, B shown. It can be seen from the figure that after adding Fe 3+ ions and reacting, the scattering intensity of TTA-TFP-COF gradually weakens with the increase of the Fe 3+ ion concentration. And in the concentration range of 2.0 - 350.0 μM, there is a good linear relationship between the degree of scattering weakening of TTA-TFP-COF and the Fe 3+ ion concentration. The fitted linear regression equation is △I = 2.1680C Fe3+ +48.5053, correlation coefficient R 2 is 0.9945, and the lowest detection limit (LOD, 3σ) is 0.7239 μM. Similarly, as shown in Figure 13 C and D, adding Cr 3+ ion solution to the TTA-TFP-COF solution will also weaken its scattering, which is proportional to the added Cr 3+ ion concentration. And in the concentration range of 40.0 - 800.0 μM, there is a good linear relationship between the scattering intensity of TTA-TFP-COF and the Cr 3+ concentration. The calibration curve is ΔI = 0.9099C Cr 3 + +524.1997, correlation coefficient (R 2 ) is 0.9932, and the detection limit (LOD, 3σ) is 1.7249 μM.

[0067] Example 3

[0068] A preparation method of a COFs material with a flower-shaped structure is as follows:

[0069] 1) Add the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (21.26 mg, 0.60 mmol) and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene (23.43 mg, 0.60 mmol) into a 10 mL centrifuge tube, add 5.0 mL of acetonitrile and shake well. Then add 35 μL of benzaldehyde and 35 μL of aniline respectively, and shake well. Then add 0.6 mL of 12 M acetic acid, shake evenly and perform ultrasonic treatment for 10.0 min until the monomers are completely dispersed;

[0070] 2) React the centrifuge tube in step 1) at room temperature for 3 days to obtain the TTA-TFP-COF crude product;

[0071] 3) Filter the TTA-TFP-COF crude product in step 2), wash it 3 times with anhydrous N,N-dimethylformamide and tetrahydrofuran in sequence, and then perform centrifugal washing with anhydrous ethanol 5 times;

[0072] 4) Collect the solid product in step 3), place it in an oven at 100 °C for drying to obtain the yellow powder TTA-TFP-COF.

[0073] The PXRD pattern of the TTA-TFP-COF synthesized in this example is shown in Figure 5 , where the abscissa represents the 2θ diffraction angle and the ordinate represents the diffraction intensity.

[0074] The morphology of the TTA-TFP-COF synthesized in this example is shown inFigure 10 and Figure 11 , which is a flower-shaped structure.

[0075] The present invention uses 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TTA) and 1,3,5-tris(4-formylphenyl)-benzene (TFP) as raw materials, and adopts different preparation methods to achieve precise control of the morphology of the TTA-TFP-COF material. The TTA-TFP-COF material with a hollow tube structure morphology prepared by the present invention can be applied to the rapid detection of Fe 3+ and Cr 3+ metal ions in aqueous solution.

[0076] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. 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. A COFs material with a regular hollow tube structure, characterized in that: The raw materials are the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene. The specific preparation steps are as follows: 1) Add the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene into a 10 mL centrifuge tube, then add acetonitrile and acetic acid and shake evenly, and ultrasonically treat for 10.0 min until the monomers are completely dispersed; 2) React the centrifuge tube in step 1) at room temperature for 1 - 6 d to obtain the TTA-TFP-COF crude product; 3) Filter the TTA-TFP-COF crude product in step 2), wash it successively with anhydrous N,N-dimethylformamide and tetrahydrofuran, and then wash it by centrifugation with anhydrous ethanol; 4) Collect the solid product in step 3), dry it in an oven at 60 - 100 °C to obtain the yellow powder TTA-TFP-COF, and its morphology is a regular hollow tube structure.

2. The COF material with a regular hollow tube structure according to claim 1, characterized in that: The molar ratio of the amino ligand 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and the aldehyde ligand 1,3,5-tris(4-formylphenyl)-benzene is 1:1, the amount of acetonitrile used is 5.0 mL, and the amount of acetic acid used is 0.3 - 1.2 mL.

3. Application of a COFs material with a regular hollow tube structure as described in claim 1, characterized in that: COF materials with a hollow tube structure can be used for the detection of Fe 3+ and Cr 3+ metal ions.

4. Use of a COF material with a regular hollow tube structure according to claim 3, characterized in that: The specific method steps are as follows: 1) Weigh the hollow tubular TTA-TFP-COF powder and disperse it in anhydrous ethanol to prepare a suspension of TTA-TFP-COF; 2) Take 20 μL of the suspension and place it in a 1.5 mL centrifuge tube. Add a solution containing Fe 3+ and Cr 3+ . Make up the volume to 1 mL with water, shake for 10 s and then let it stand for 20 min; 3) Detect the scattering intensity of the mixture obtained in step 2).

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