A covalent organic framework material and its preparation method and application

Abstract

The present application relates to the field of chemical analysis technology, and in particular to a covalent organic framework material and its preparation method and application. The chemical composition of the covalent organic framework material includes: terephthalaldehyde and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin; wherein the weight ratio of the terephthalaldehyde to the 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is 2 to 4:5. The content of the present application solves the technical problem that the existing covalent organic framework materials have poor stability in analysis and detection.

Description

Technical Field

[0001] The present application relates to the field of chemical analysis technology, and in particular to a covalent organic framework material and a preparation method and application thereof. Background Art

[0002] Covalent organic frameworks (COFs) are a type of crystalline organic polymer with a porous structure that is constructed by covalently linking light elements such as C, H, B, O, and N. As nanozymes, COFs have good oxide-mimicking enzyme activity, but unstable hydrogen peroxide needs to be added during the detection of ascorbic acid (vitamin C, Vc), which increases costs and reduces the stability of the test results. Summary of the invention

[0003] The present application provides a covalent organic framework material and a preparation method and application thereof, in order to solve the technical problem that the existing covalent organic framework materials have poor stability in analysis and detection.

[0004] In a first aspect, the present application provides a covalent organic framework material, the chemical composition of the covalent organic framework material comprising:

[0005] Terephthalaldehyde and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin; wherein,

[0006] The weight ratio of the terephthalaldehyde to the 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is 2-4:5.

[0007] Optionally, the weight ratio of the terephthalaldehyde to the 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is 3:5.

[0008] In a second aspect, the present application provides the use of the covalent organic framework material described in any embodiment of the first aspect in detecting ascorbic acid.

[0009] In a third aspect, the present application provides a method for preparing a covalent organic framework material, which is used to prepare the covalent organic framework material described in any embodiment of the first aspect, and the method comprises:

[0010] terephthalaldehyde, 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and a solvent are mixed, and then heated at a set temperature to obtain a reaction solution;

[0011] The reaction solution is centrifuged and dried to obtain a covalent organic framework material.

[0012] Optionally, the set temperature is 50-150°C.

[0013] Optionally, the set temperature is 90°C.

[0014] Optionally, the heating time is 24 to 72 hours.

[0015] Optionally, the heating time is 48 hours.

[0016] Optionally, the solvent is dimethyl sulfoxide, and the volume V of the dimethyl sulfoxide and the weight M of the terephthalaldehyde satisfy the relationship: V:M=1-3:1.

[0017] Optionally, the volume V of the dimethyl sulfoxide and the weight M of the terephthalaldehyde satisfy the relationship: V:M=1:1.

[0018] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0019] The covalent organic framework material (COFs) provided in the embodiment of the present application has oxidase catalytic properties and can effectively prevent and control the aggregation of porphyrins. The porous structure of COFs is conducive to the aggregation of substrates, enhances electron transfer, and enhances the catalytic activity of the enzyme. The COFs enzyme mimic can directly catalyze the TMB reaction without the presence of hydrogen peroxide, which makes the operation simpler, improves the stability and accuracy of the reaction system, reduces costs, and reduces pollution to the environment. The enzyme mimic can be used to detect ascorbic acid at room temperature, which is simple, fast, highly sensitive, and has very strong practical application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 A synthesis process of a COFs mimic enzyme provided in the embodiments of the present application;

[0023] Figure 2 SEM and TEM images of a COFs enzyme mimic provided in the examples of the present application;

[0024] Figure 3 An XRD diagram of a COFs enzyme mimic provided in an embodiment of the present application;

[0025] Figure 4An infrared spectrum of a COFs enzyme mimic provided in an embodiment of the present application;

[0026] Figure 5 This is an XPS graph of a COFs enzyme mimic provided in an embodiment of the present application;

[0027] Figure 6 A 13C NMR image of a COFs mimetic enzyme provided in an embodiment of the present application;

[0028] Figure 7 A diagram of the catalytic activity of a COFs-mimicking enzyme provided in an embodiment of the present application;

[0029] Figure 8 An enzyme kinetic diagram of a COFs-mimicking enzyme provided in an embodiment of the present application;

[0030] Fig. 9 The response of a detection platform to ascorbic acid at different reaction times provided in an embodiment of the present application;

[0031] Fig.10 The response of the detection platform to ascorbic acid at different pH values ​​provided in the embodiments of the present application;

[0032] Fig.11 The response of the different reaction temperature detection platforms provided in the embodiments of the present application to ascorbic acid;

[0033] Fig.12 The detection results and linear calibration curve of a COFs mimetic enzyme for different concentrations of ascorbic acid provided in the embodiments of the present application;

[0034] Fig.13 A COFs mimetic enzyme specific detection result for ascorbic acid provided in the examples of the present application;

[0035] Fig.14 The catalytic performance of COFs prepared under different synthesis conditions provided in the examples of this application;

[0036] Fig.15 A method for preparing COFs is provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0038] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0039] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc or abc, where a, b, c can be single or plural, respectively.

[0040] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0041] In a first aspect, the present application provides a covalent organic framework material, the chemical composition of the covalent organic framework material comprising:

[0042] Terephthalaldehyde and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin; wherein,

[0043] The weight ratio of the terephthalaldehyde to the 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is 2-4:5.

[0044] In some embodiments, the weight ratio of the terephthalaldehyde to the 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is 3:5.

[0045] In the covalent organic framework material, the role of terephthalaldehyde is to link the framework of the covalent organic framework material. The role of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is the main source of the catalytic function of the covalent framework material.

[0046] The positive effect of controlling the weight ratio of terephthalaldehyde to 5,10,15,20-tetrakis(4-aminophenyl)porphyrin to be 2 to 4:5: the catalytic function of the product. If the content of terephthalaldehyde is too high or the content of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is too low, the catalytic performance of the product will be reduced to a certain extent; if the content of terephthalaldehyde is too low or the content of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is too high, the yield of the product will be reduced to a certain extent. Specifically, the weight ratio of terephthalaldehyde to 5,10,15,20-tetrakis(4-aminophenyl)porphyrin can be 2:5, 3:5, 4:5, etc. Preferably, the weight ratio is 3:5.

[0047] In a second aspect, the present application provides the use of the covalent organic framework material described in any embodiment of the first aspect in detecting ascorbic acid.

[0048] Ascorbic acid (vitamin C, Vc) is a water-soluble vitamin essential to the human body and is widely found in fresh fruits and vegetables. Due to its good antioxidant activity, ascorbic acid can maintain the normal function of the immune system and prevent gum bleeding. Since the human body cannot synthesize ascorbic acid, it can only be ingested from the outside. Excessive intake and insufficient intake can lead to certain diseases. At present, vegetables and fruits are the main sources of ascorbic acid for the human body. In addition, ascorbic acid, as a natural antioxidant, is widely used in medical pharmaceuticals, food processing and cosmetics. Therefore, it is very important to use a highly sensitive and simple method to analyze the ascorbic acid content in food and drugs. At present, the detection methods of Vc include titration, chromatography, capillary electrophoresis, electrophoresis and fluorescence. Among the many detection methods, the colorimetric method judges the content of the analyte by the change in the color of the reaction system, which has the unique advantages of being simple, fast, visible to the naked eye and low cost. However, the enzyme required for the colorimetric method has the problems of poor stability and harsh storage conditions, which affects the stability of the detection. In order to improve the stability of the detection, it is necessary to improve the stability of the enzyme in the colorimetric process.

[0049] The covalent organic framework material (COFs) of the first aspect has oxidase catalytic properties. The enzyme simulation can be used to detect ascorbic acid at room temperature. It is simple, fast and highly sensitive, and has very strong practical application prospects.

[0050] In the third aspect, the present application provides a method for preparing a covalent organic framework material, see Fig.15 , used to prepare the covalent organic framework material according to any one of the embodiments of the first aspect, the method comprising:

[0051] S1, mixing terephthalaldehyde, 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and a solvent, and then heating at a set temperature to obtain a reaction solution;

[0052] S2. Centrifuging and drying the reaction solution to obtain a covalent organic framework material.

[0053] In some embodiments, the set temperature is 50-150°C.

[0054] In some embodiments, the set temperature is 90°C.

[0055] "Set temperature" means the temperature of the above heating. The positive effect of controlling the above heating temperature to 50-150°C is to meet the requirements of production, cost, environmental protection, etc. If the temperature is too high, the by-product content will increase to a certain extent; if the temperature is too low, the synthesis efficiency will be reduced to a certain extent. Specifically, the temperature can be 50°C, 100°C, 150°C, etc. Preferably, the temperature can be 90°C.

[0056] In some embodiments, the heating time is 24 to 72 hours.

[0057] In some embodiments, the heating time is 48 hours.

[0058] The positive effect of controlling the heating time to 24 to 72 hours is to meet the requirements of cost and product yield. If the time is too long, the time cost and by-product content will increase to a certain extent; if the time is too short, the synthesis yield will be reduced to a certain extent. Specifically, the heating time can be 24 hours, 30 hours, 40 hours, 50 hours, 60 hours, 72 hours, etc., and the preferred heating time is 48 hours.

[0059] In some embodiments, the solvent is dimethyl sulfoxide, and the volume V of the dimethyl sulfoxide and the weight M of the terephthalaldehyde satisfy the relationship: V:M=1-3:1.

[0060] In some embodiments, the volume V of the dimethyl sulfoxide and the weight M of the terephthalaldehyde satisfy the relationship: V:M=1:1.

[0061] The positive effect of using dimethyl sulfoxide as solvent is to obtain the best reaction rate and product yield.

[0062] The positive effect of controlling the ratio of the volume of dimethyl sulfoxide to the weight of the terephthalaldehyde to be 1 to 3:1 is to ensure the reaction rate and product yield. If the volume of dimethyl sulfoxide is too large or the weight of terephthalaldehyde is too small, the reaction rate will be affected to a certain extent; if the volume of dimethyl sulfoxide is too small or the weight of terephthalaldehyde is too large, the product yield will be affected to a certain extent. Specifically, the ratio can be 1:1, 2:1, 3:1, etc. Preferably, the ratio is 1:1.

[0063] The preparation method of the covalent organic framework material is based on the above-mentioned covalent organic framework material. The specific chemical composition of the covalent organic framework material can refer to the above-mentioned embodiment. Since the preparation method of the covalent organic framework material adopts part or all of the technical solutions of the above-mentioned embodiment, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here one by one.

[0064] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0065] Preparation of COFs:

[0066] S1, mixing terephthalaldehyde, 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and dimethyl sulfoxide solution, and then heating at a set temperature to obtain a reaction solution;

[0067] S2. Centrifuging and drying the reaction solution to obtain a covalent organic framework material.

[0068] Table 1 Components of covalent organic framework materials

[0069]

[0070] Example 1

[0071] Weigh 6 mg of terephthalaldehyde and dissolve it in 6 mL of dimethyl sulfoxide solution, add 10 mg of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin, mix well, and react at 90°C for 48 hours. Centrifuge at 8000 rpm / min for 5 minutes, wash the collected solid with tetrahydrofuran and ethanol three times, and dry the white solid in a vacuum oven at 65°C overnight. The obtained solid is the COFs1 material.

[0072] Example 2

[0073] Weigh 4 mg of terephthalaldehyde and dissolve it in 8 mL of dimethyl sulfoxide solution, add 10 mg of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin, mix well, and react at 50°C for 40 hours. Centrifuge at 8000 rpm / min for 5 minutes, wash the collected solid with tetrahydrofuran and ethanol three times, and dry the white solid in a vacuum oven at 60°C overnight. The obtained solid is the COFs2 material.

[0074] Example 3

[0075] Weigh 8 mg of terephthalaldehyde and dissolve it in 24 mL of dimethyl sulfoxide solution, add 10 mg of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin, mix well, and react at 150°C for 24 hours. Centrifuge at 8000 rpm / min for 5 minutes, wash the collected solid with tetrahydrofuran and ethanol three times, and dry the white solid in a vacuum oven at 80°C overnight. The obtained solid is COFs3 material.

[0076] Among them, 1 is TMB colorimetric solution, 2 is COFs1+TMB colorimetric solution, 3 is COFs2+TMB colorimetric solution, and 4 is COFs3+TMB colorimetric solution. Figure 1 The preparation process of COFs can be known from Fig.14 It can be seen that the color change of solution 2 is the most obvious, while the color changes of other solutions are not obvious, indicating that COFs1 has a good catalytic effect on TMB, and the oxidase catalytic effect of COFs2 and COFs3 is weaker than that of COFs1. Therefore, the material synthesized under the conditions of Example 1 has the best oxidase catalytic performance. Figure 2 From the SEM and TEM images, we can see that COFs is a spherical structure. Figure 3 , Figure 4 , Figure 5 and Figure 6 Further detection and analysis revealed that COFs have a uniform chemical structure and regular crystal configuration, confirming that this method formed COFs materials.

[0077] The catalytic activity test was carried out using the COF prepared in Example 1

[0078] (1) Oxidase catalytic activity

[0079] Take 1 mg of COFs material, add 1 mL of aqueous solution, mix well, and prepare 1 mg / mL COFs suspension. Take 500 μL of COFs suspension, add 500 μL of TMB solution, react for 0.5 h in the dark, take a photo with a camera, and use a functional microplate reader to test the absorbance at 650 nm.

[0080] (2) Kinetic catalytic constant

[0081] Take 500 μL COFs suspension, add different volumes of TMB solution (0, 10, 50, 100, 250, 500, 750, 1000, 1250, 1500, 1750, 2000 μL), add water to a total volume of 2500 μL, and react in dark for 0.5 h. Use a functional microplate reader to measure the absorbance at 650 nm, and plot the TMB concentration and absorbance value to obtain the catalytic kinetic curve of the COFs mimic enzyme. Use the COF prepared in Example 1 to detect ascorbic acid

[0082] (1) Determination of standard curve

[0083] COF (200 μL, 1 mg / mL) and TMB (100 μL, 0.3 mg / mL) were mixed in a ratio of 1:1 and reacted at room temperature for 90 min. Standard solutions of different concentrations were prepared using ascorbic acid standards and dissolved in pure water solutions to prepare multiple ascorbic acid standard solutions. The standard solutions of different concentrations were added dropwise to the COFs-TMB system.

[0084] (2) Specificity detection

[0085] Different types of competing substances (sodium chloride, potassium chloride, calcium chloride, glucose, mannose, glycine, cholesterol, phenylalanine, uric acid) were used to prepare a 10 mg / mL solution to prepare a 1 mg / mL standard mixed solution of ascorbic acid. Different types of competing substances were mixed with the 1 mg / mL standard solution of ascorbic acid in equal proportions, and the fluorescence signal was measured after 5 minutes of reaction.

[0086] 1) preparing different standard solutions with a standard substance of ascorbic acid, and dissolving them in pure aqueous solution respectively to prepare a plurality of standard solutions of ascorbic acid;

[0087] 2) using different types of competitive substances to prepare a concentration of 10 mg / mL, and mixing the different types of competitive substances with the standard solution of ascorbic acid to prepare a plurality of different types of standard mixed solutions of ascorbic acid;

[0088] 3) adding standard solutions of different concentrations dropwise to the covalent organic framework material solution, and after reacting for 5 minutes, taking pictures with a camera, and reading the ultraviolet signal with a multifunctional microplate reader to establish a linear relationship between the ascorbic acid concentration and the ultraviolet signal;

[0089] 4) adding different types of competitive substance solutions and a standard mixed solution of ascorbic acid to the covalent organic framework material solution, and after reacting for 5 minutes, taking pictures with a camera, and reading the ultraviolet signal with a multifunctional microplate reader, and comparing the changes in the ultraviolet signal with and without the presence of ascorbic acid.

[0090] The optimal reaction time ( Fig. 9 )、pH( Fig.10 ) and temperature ( Fig.11 ). Standard solutions of different concentrations were prepared with standard ascorbic acid, and dissolved in pure water solution respectively to prepare multiple standard ascorbic acid solutions. Under the optimal reaction conditions, standard solutions of different concentrations were added dropwise to the COFs-TMB system, and the UV signal was read with a multifunctional microplate reader to establish a linear relationship between the ascorbic acid concentration and the UV signal ( Fig.12 ). Fig.13 The results show that the sensor of the present invention has satisfactory specificity.

[0091] Recovery experiment of ascorbic acid in the effervescent tablets and strawberry samples of COFs nanozymes based on Example 1

[0092] Take an appropriate amount of Vc effervescent tablets, grind them into powder with a mortar, accurately weigh 5.00g of powder into a 100mL beaker, add a certain amount of Vc standard solution to make the final concentrations 3.33, 33.30, and 100.00μg / g, and mix well. Add 50mL of oxalic acid solution (20g / L), transfer to a 100mL volumetric flask after fully dissolving, dilute to 100mL with 20g / L oxalic acid solution, and filter the solution for later use.

[0093] Take an appropriate amount of strawberry sample and homogenize it with a homogenizer. Accurately weigh 5.00g of the homogenized sample into a 100mL beaker, add a certain amount of Vc standard solution to make the final concentrations 3.33, 33.30, and 100.00μg / g, and mix well. Add 50mL of oxalic acid solution (20g / L), transfer to a 100mL volumetric flask after fully dissolving, and dilute to 100mL with 20g / L oxalic acid solution. Filter the solution for later use.

[0094] Table 2 Vc spike recovery experiment in actual samples

[0095]

[0096] From Table 2, it can be found that the recovery rate of Vc detected by the method of the embodiment of this application is consistent with the recovery rate in the national standard, which shows that this method technology has great potential in practical application.

[0097] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. Application of a covalent organic framework material in the detection of ascorbic acid, It is characterized in that The application includes simulating a covalent organic framework material into an oxidase to directly catalyze a TMB reaction without adding hydrogen peroxide. The chemical composition of the covalent organic framework material includes: Terephthalaldehyde and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin; wherein, The weight ratio of terephthalaldehyde to 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is 2 to 4:5; The preparation method of the covalent organic framework material comprises: terephthalaldehyde, 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and a solvent are mixed, and then heated at a set temperature to obtain a reaction solution; The reaction solution is centrifuged and dried to obtain a covalent organic framework material.

2. The use according to claim 1, It is characterized in that The weight ratio of the terephthalaldehyde to the 5,10,15,20-tetrakis(4-aminophenyl)porphyrin is 3:

5.

3. The use according to claim 1, It is characterized in that The set temperature is 50-150°C.

4. The use according to claim 3, It is characterized in that The set temperature is 90°C.

5. The use according to claim 1, It is characterized in that The heating time is 24 to 72 hours.

6. The use according to claim 5, It is characterized in that The heating time is 48 h.

7. The use according to claim 1, It is characterized in that The solvent is dimethyl sulfoxide, and the volume V of the dimethyl sulfoxide and the weight M of the terephthalaldehyde satisfy the relationship: V:M=1-3:1, wherein the unit of the volume V is mL, and the unit of the weight M is mg.

8. The use according to claim 7, It is characterized in that The volume V of the dimethyl sulfoxide and the weight M of the terephthalaldehyde satisfy the relationship: V:M=1:1.

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