An azobenzene-based calixarene porous organic polymer and its preparation and application

Abstract

The present invention discloses an azobenzene calixarene porous organic polymer, which is connected by azobenzene calixarene through alkyne functional groups. This polymer material has a large specific surface area and a high content of functional groups, and has excellent extraction performance for triphenylmethane dyes in food. It can improve the sample pretreatment efficiency of triphenylmethane dyes in food, reduce the matrix interference of target analytes, and achieve accurate analysis and detection of triphenylmethane dyes in foods such as aquatic products. In addition, this material has a long service life and good repeatability.

Description

Technical Field

[0001] The present invention relates to an azobenzene calixarene porous organic polymer and a preparation method thereof; the present invention also uses the azobenzene calixarene porous organic polymer as a sample pretreatment material for the extraction and enrichment of triphenylmethane dyes, and realizes the separation and analysis of triphenylmethane dyes in foods, belonging to the technical field of analytical detection. Background Art

[0002] Triphenylmethane dyes such as malachite green and crystal violet have been widely used as bactericidal preservatives due to their excellent effects in preventing and treating infectious diseases of aquatic products. However, after the carcinogenicity and mutagenicity of malachite green and crystal violet were discovered, they were prohibited from being used in aquatic products in 2002. Recently, some researchers have used brilliant green and the derivative basic blue (VPBO) of triphenylmethane victoria pure blue with good anti-corrosion performance to replace malachite green, but its structure is similar to that of malachite green and may have similar toxicity. Some scholars have reported that brilliant green and basic blue may cause skin sensitization or necrosis, and ingestion or inhalation of brilliant green and basic blue may irritate the gastrointestinal tract and respiratory tract. At present, the application of triphenylmethane dyes and their possible substitutes is very complex and is extremely likely to be abused in aquatic products. And some unknown dyes that have not been banned are more likely to cause potential hazards. Therefore, it is very important to effectively detect triphenylmethane dyes.

[0003] At present, the main method for detecting triphenylmethane dyes is high performance liquid chromatography (HPLC). However, due to the complexity of aquatic products causing matrix interference and the low level of dye residues in food samples, technical indicators such as low recovery rate and lower limit of quantification cannot meet the measurement requirements. Therefore, the development of an efficient sample pretreatment technology is an important link to achieve sensitive detection of triphenylmethane dyes in aquatic products. Solid phase extraction technology is the most widely used because of its characteristics such as less solvent consumption, low cost, short time, high enrichment efficiency and recovery rate, and is easy to realize automation and connection with other analytical instruments. The core of solid phase extraction technology is the extraction material. In recent years, porous organic polymers (POPs) have received increasing attention in the field of sample preparation due to their unique physical and chemical properties such as high specific surface area, low framework density and high chemical stability. Compared with classical inorganic porous materials such as molecular sieves and inorganic-organic hybrid porous materials such as metal-organic frameworks, the great advantage of porous organic polymers is that specific organic structural units and synthesis techniques can be selected to adjust the pore parameters and framework properties of the polymer. However, there is no relevant report on using porous organic polymers for the extraction and analysis detection of triphenylmethane dyes in foods. Summary of the Invention

[0004] In view of the current status and deficiencies in the pretreatment, analysis and detection of triphenylmethane dyes in foods, the purpose of the present invention is to provide an azobenzene calixarene porous organic polymer and a preparation method thereof; and to use it for the efficient extraction of triphenylmethane dyes in foods, and combined with HPLC detection technology, an analytical determination method is established to realize the analysis and determination of triphenylmethane dyes in food samples.

[0005] I. Azobenzene calixarene porous organic polymer

[0006] The azobenzene calixarene porous organic polymer of the present invention is formed by connecting azobenzene calixarenes through alkyne functional groups, and has the following chemical structure:

[0007]

[0008] In the formula, the substituent R1 is independently selected from any one of hydrogen, methyl, ethyl, and propyl; R2 and R3 are independently selected from any one of hydrogen, methyl, halogen, nitro, carboxyl, sulfonic acid group, hydroxyl group, and amino group.

[0009] The preparation method of the azobenzene calixarene porous organic polymer is to dissolve azobenzene calixarene in an organic solvent, add bis(triphenylphosphine)palladium dichloride and copper iodide, stir for 5 - 10 min, then add an alkyne compound and a base, and react at 25 - 120 °C for 24 - 100 hours under nitrogen protection. After the reaction is completed, it is washed successively with an organic solvent and water, and dried to obtain the target organic polymer. Marked as POPs material.

[0010] The structural formula of the azobenzene calixarene is shown as follows. The synthesis of azobenzene calixarene refers to the literature ( Spectrochim. Acta, Part A. 2015, 142, 178 )

[0011]

[0012] Among them: the substituent R1 is independently selected from any one of hydrogen, methyl, ethyl, and propyl;

[0013] The alkyne compound is an important reaction raw material for synthesizing the target compound, and its structural formula is shown as follows:

[0014]

[0015] Among them: R2 and R3 are independently selected from any one of hydrogen, methyl, halogen, nitro, carboxyl, sulfonic acid group, hydroxyl group, and amino group.

[0016] In the above reaction, the organic solvent is at least one of tetrahydrofuran, acetonitrile, dichloromethane, benzene, toluene, xylene, chlorobenzene, chloroform, methanol, ethanol, petroleum ether, N,N-dimethylformamide, and dimethyl sulfoxide. The mass ratio of azobenzene calixarene to the alkyne compound is 5:1 to 1:1.

[0017] Both bis(triphenylphosphine)palladium dichloride and copper iodide are catalysts required for the reaction. The mass ratio of azobenzene calixarene to bis(triphenylphosphine)palladium dichloride is 3:1 to 1:1; the mass ratio of azobenzene calixarene to copper iodide is 12:1 to 5:1.

[0018] The purpose of adding the base is to provide a basic environment for the reaction. The base can be an organic base or an inorganic base; among them, the organic base is triethylamine, pyridine, diisopropylamine, or 4-dimethylaminopyridine; the inorganic base is at least one of sodium carbonate, potassium carbonate, sodium hydroxide, cesium carbonate, sodium bicarbonate, potassium bicarbonate, or barium carbonate. The molar ratio of azobenzene calixarene to the base is 80:1 to 20:1.

[0019] The synthesis formula of the above azobenzene calixarene porous organic polymer is as follows:

[0020]

[0021] Figure 1 This is the solid-state NMR spectrum of the POPs prepared in the present invention. Figure 1 It shows that the adsorption peak near 152 ppm corresponds to the phenoxy carbon of calix[4]arene, the chemical shifts in the range of 115 - 140 ppm are assigned to the benzene carbons of calix[4]arene and the linker, and the peaks near 85 ppm and 30 ppm belong to the alkyne carbon of the linker and the methylene carbon of the macrocycle respectively, indicating the successful synthesis of the porous organic polymer.

[0022] Figure 2 This is the transmission electron microscopy characterization diagram of the POPs material prepared in the present invention. As Figure 2 shown, the obtained porous organic polymer is an amorphous network structure, and there are many ordered pores on the material surface, providing abundant adsorption sites for the extraction of target analytes.

[0023] Figure 3 This is the specific surface area test diagram of the POPs material prepared in the present invention. The test results show that the porous organic polymer has a relatively large BET specific surface area of 80.74 m²·g -1 , and the average pore diameter is about 18.43 nm. It shows that the prepared POPs material has a large specific surface area, strong hydrophobic cavities and negative charge structures, can form electrostatic interactions with positively charged analytes to be measured, and has great potential for the solid-phase extraction of triphenylmethane dyes in food.

[0024] II. Application of Azobenzene Calixarene Porous Organic Polymer in Sample Pretreatment

[0025] (1) Place 2.0 - 100 mg (preferably 10 mg) of the above - prepared POPs material in 1 - 10 mL (preferably 2 mL) of a solution containing five triphenylmethane dye test solutions (malachite green, rhodamine B, crystal violet, brilliant green, basic blue) with a concentration of 2 - 50 mg·L -1 (20 mg·L -1 ). After ultrasonic treatment for 1 - 5 min (preferably 2 min), place it on an oscillator and oscillate for 5 - 60 min (preferably 10 min) to achieve extraction equilibrium. Then perform centrifugation to separate the POPs material from the aqueous phase, and measure the five triphenylmethane dyes in the aqueous phase.

[0026] (2) Transfer the separated POPs material to a centrifuge tube, add an eluent, and perform ultrasonic treatment for 0.5 - 20 min (preferably 5 min) to desorb the target analyte from the POPs extraction material. Repeat the above operation 3 times, combine the desorbed solutions, and measure their concentrations using HPLC. Thus, calculate the content of triphenylmethane dyes in the original test sample.

[0027] The eluent can be a mixed solution of methanol and acid solution or a mixed solution of acetonitrile and acid solution. The acid solution can be selected from formic acid, acetic acid, and trifluoroacetic acid. The volume ratio of the acid solution is 0.1% - 5%. Preferably, the eluent is a mixed solution of acetonitrile and trifluoroacetic acid, and the volume ratio of the acid solution is 1%.

[0028] Figure 4 Analysis and detection diagrams of five triphenylmethane dyes before and after extraction by POPs material under preferred conditions: (1) Malachite green; (2) Rhodamine B; (3) Crystal violet; (4) Brilliant green; (5) Basic blue. It can be seen from Figure 4 that the enrichment effects of the five target analytes (triphenylmethane dyes) after enrichment by the POPs material are all obvious, and the maximum enrichment factor can reach 100 times (crystal violet).

[0029] In addition, the experiment also found that the porous organic polymer material prepared by the present invention has good stability, a long service life, and can be reused more than 10 times.

[0030] In summary, the azobenzene-calixarene porous organic polymer POPs prepared by the present invention is formed by connecting azobenzene-calixarene through alkynyl functional groups. This polymer material has a large specific surface area and a high content of functional groups, and has excellent extraction performance for triphenylmethane dyes in food. It can improve the sample pretreatment efficiency of triphenylmethane dyes in food, increase the recovery rate of sample pretreatment, improve its detection sensitivity, reduce the matrix interference of target analytes, and achieve the precise analysis and detection of triphenylmethane dyes in foods such as aquatic products. Description of the Drawings

[0031] Figure 1 It is the solid nuclear magnetic spectrum of POPs.

[0032] Figure 2 It is the transmission electron microscopy characterization diagram of the POPs material.

[0033] Figure 3 It is the specific surface area test diagram of the POPs material.

[0034] Figure 4 It is the analysis and detection diagram of five triphenylmethane dyes before and after extraction of the POPs material: (1) malachite green; (2) rhodamine B; (3) crystal violet; (4) brilliant green; (5) basic blue. Detailed Embodiments

[0035] Hereinafter, the present invention further illustrates the preparation and performance of the POPs material of the present invention through specific examples.

[0036] Example 1

[0037] (1) Dissolve compound 1 (115 mg) in anhydrous tetrahydrofuran (5 mL). Under nitrogen protection, add bis(triphenylphosphine)palladium dichloride (35 mg) and copper iodide (10 mg). After stirring for 5 minutes, dropwise add a tetrahydrofuran solution (2 mL) containing 1,4-diethynylbenzene (52 mg) and diisopropylamine (50 μL). After the above solution is stirred for 10 minutes under nitrogen protection, heat it at 65 °C for 72 hours. After cooling to room temperature, filter to obtain a solid, wash it successively with tetrahydrofuran, dichloromethane, methanol and water, and then dry it to obtain the azobenzene-calixarene porous organic polymer material (POPs-1). The reaction structural formula is as follows:

[0038]

[0039] (2) Place 10 mg of the material POPs-1 prepared above in 2 mL of a solution containing a concentration of 20 mg·L -1For the five triphenylmethane dye test solutions (malachite green, rhodamine B, crystal violet, brilliant green, basic blue), after ultrasonic treatment for 2 min, place them on an oscillator and oscillate for 10 min to achieve extraction equilibrium. Subsequently, centrifuge to separate POPs-1 from the aqueous phase, and determine the five triphenylmethane dyes in the aqueous phase;

[0040] (3) Transfer the separated material POPs-1 to a centrifuge tube, add a mixed solution of acetonitrile and trifluoroacetic acid (the volume ratio of the acid solution is 1%) as the eluent, and ultrasonicate for 5 min to desorb the target analyte from the material POPs-1. Repeat the above operation 3 times, combine the desorbed solutions, and determine their concentrations using HPLC. Calculate the content of triphenylmethane dyes in the original test sample. The analysis and detection diagrams of the five triphenylmethane dyes before and after extraction of the test sample by the POPs-1 material are as Figure 4 : (1) Malachite green; (2) Rhodamine B; (3) Crystal violet; (4) Brilliant green; (5) Basic blue. As can be seen from Figure 4 it, the enrichment effects of the five target analytes (triphenylmethane dyes) to be measured after enrichment by the POPs-1 material are all obvious, and the maximum enrichment factor can reach 100 times.

[0041] Example 2

[0042] (1) Dissolve compound 2 (130 mg) in anhydrous tetrahydrofuran (5 mL). Under nitrogen protection, add bis(triphenylphosphine)palladium dichloride (35 mg) and copper iodide (10 mg). After stirring for 5 minutes, dropwise add a tetrahydrofuran solution (2 mL) containing 1,4-diethynylbenzene (52 mg) and triethylamine (80 μL). After stirring the above solution under nitrogen protection for 10 minutes, heat it at 50 °C for 36 hours. After cooling to room temperature, filter to obtain a solid, wash it successively with N,N-dimethylformamide, dichloromethane, ethanol, and water, and then dry it to obtain an azophenylcalixarene porous organic polymer material (POPs-2). The reaction structural formula is as follows:

[0043]

[0044] (2) Application of the material POPs-2: The same as in Example 1.

[0045] Example 3

[0046] (1) Dissolve compound 3 (54 mg) in acetonitrile (5 mL). Under nitrogen protection, add bis(triphenylphosphine)palladium(II) dichloride (54 mg) and copper(I) iodide (15 mg). After stirring for 5 minutes, dropwise add an acetonitrile solution (2 mL) containing 2-amino-1,4-diethynylbenzene (52 mg) and sodium carbonate (0.04 g). After stirring the above solution for 10 minutes under nitrogen protection, heat it at 100 °C for 36 hours. After cooling to room temperature, filter to obtain a solid, wash it successively with tetrahydrofuran, dichloromethane, methanol, and water, and then dry it to obtain the azobenzene calixarene porous organic polymer material (POPs-3). The reaction structural formula is as follows:

[0047]

[0048] (2) Application of the material POPs-3: The same as in Example 1.

[0049] Example 4

[0050] (1) Dissolve compound 4 (115 mg) in chloroform (5 mL). Under nitrogen protection, add bis(triphenylphosphine)palladium(II) dichloride (87 mg) and copper(I) iodide (45 mg). After stirring for 5 minutes, dropwise add a chloroform solution (2 mL) containing 2-methyl-1,4-diethynylbenzene (52 mg) and sodium hydroxide (0.04 g). After stirring the above solution for 10 minutes under nitrogen protection, heat it at 80 °C for 96 hours. After cooling to room temperature, filter to obtain a solid, wash it successively with tetrahydrofuran, dichloromethane, methanol, and water, and then dry it to obtain the azobenzene calixarene porous organic polymer material (POPs-4). The reaction structural formula is as follows:

[0051]

[0052] (2) Application of the material POPs-4: The same as in Example 1.

[0053] Example 5

[0054] (1) Dissolve compound 5 (115 mg) in toluene (5 mL). Under nitrogen protection, add bis(triphenylphosphine)palladium(II) dichloride (32 mg) and copper(I) iodide (15 mg). After stirring for 5 minutes, dropwise add a toluene solution (2 mL) containing 2-methyl-1,4-diethynylbenzene (52 mg) and pyridine (40 μL). After stirring the above solution for 10 minutes under nitrogen protection, heat it at 120 °C for 24 hours. After cooling to room temperature, filter to obtain a solid, wash it successively with tetrahydrofuran, dichloromethane, methanol, and water, and then dry it to obtain the azobenzene calixarene porous organic polymer material (POPs-5). The reaction structural formula is as follows:

[0055]

[0056] (2) Application of Material POPs-5: The same as in Example 1.

Claims

1. A preparation method of an azophenylcalixarene porous organic polymer, which comprises dissolving azophenylcalixarene in an organic solvent, adding bis(triphenylphosphine)palladium dichloride and cuprous iodide, stirring for 5 - 10 min, then adding a base and an alkyne compound, and reacting at 25 - 120 °C for 24 - 100 hours under nitrogen protection; after the reaction is completed, washing with an organic solvent and water in sequence, and drying to obtain the azophenylcalixarene porous organic polymer; The structural formula of the azophenylcalixarene is as shown in the following formula: Wherein: The substituent R1 is independently selected from any one of hydrogen, methyl, ethyl, and propyl; The structural formula of the alkyne compound is as shown in the following formula: Wherein: R2 and R3 are independently selected from any one of hydrogen, methyl, halogen, nitro, carboxyl, sulfonic acid group, hydroxyl, and amino; The structural formula of the azophenylcalixarene porous organic polymer is as shown in the following formula: Wherein: the substituent R1 is independently selected from any one of hydrogen, methyl, ethyl, and propyl; R2 and R3 are independently selected from any one of hydrogen, methyl, halogen, nitro, carboxyl, sulfonic acid group, hydroxyl, and amino.

2. The preparation method of an azobenzene-calixarene porous organic polymer according to claim 1, characterized in that: The mass ratio of the azophenylcalixarene to the alkyne compound is 5:1 - 1:

1.

3. The preparation method of an azobenzene-calixarene porous organic polymer according to claim 1, characterized in that: The organic solvent is at least one of tetrahydrofuran, acetonitrile, dichloromethane, benzene, toluene, xylene, chlorobenzene, chloroform, methanol, ethanol, petroleum ether, N,N-dimethylformamide, and dimethyl sulfoxide.

4. The preparation method of an azobenzene-based calixarene porous organic polymer as claimed in claim 1, characterized in that: The mass ratio of the azophenylcalixarene to bis(triphenylphosphine)palladium dichloride is 3:1 - 1:1; the mass ratio of the azophenylcalixarene to cuprous iodide is 12:1 - 5:

1.

5. The preparation method of an azobenzene-calixarene porous organic polymer according to claim 1, characterized in that: The base is an organic base or an inorganic base; wherein the organic base is triethylamine, pyridine, diisopropylamine, or 4-dimethylaminopyridine; the inorganic base is at least one of sodium carbonate, potassium carbonate, sodium hydroxide, cesium carbonate, sodium bicarbonate, potassium bicarbonate, and barium carbonate, and the molar ratio of the azophenylcalixarene to the base is 80:1 - 20:

1.

6. The application of the azophenylcalixarene porous organic polymer prepared by the method as described in claim 1 as a solid-phase extraction agent in extracting triphenylmethane dyes in food, which comprises the following steps: (1) Place 2.0 - 100 mg of azobenzene calixarene porous organic polymer into 1 - 10 mL of the test solution of triphenylmethane dye with a concentration of 2 - 50 mg·L -1 and ultrasonicate for 1 - 5 min, then place it on an oscillator and oscillate for 5 - 60 min to achieve extraction equilibrium; subsequently, centrifuge to separate the azobenzene calixarene porous organic polymer from the aqueous phase; (2) Transfer the separated azophenylcalixarene porous organic polymer into a centrifuge tube, add an eluent, and ultrasonicate for 0.5 - 20 min to desorb the target analyte from the azophenylcalixarene porous organic polymer; repeat the above operation 3 times, combine the desorbed solutions, and determine its concentration by HPLC, so as to calculate the content of triphenylmethane dyes in the original sample to be measured.

7. Use of the azobenzene-calixarene porous organic polymer as a solid-phase extractant according to claim 6 in extracting triphenylmethane dyes in foods, characterized in that: The triphenylmethane dyes are malachite green, rhodamine B, crystal violet, brilliant green, and basic blue.

8. Use of the azobenzene calixarene porous organic polymer as a solid phase extraction agent according to claim 6 in extracting triphenylmethane dyes in foods, characterized in that: The eluent is a mixed solution of methanol and an acid solution or a mixed solution of acetonitrile and an acid solution, the acid solution is selected from one of formic acid, acetic acid, and trifluoroacetic acid, and the volume ratio of the acid solution is 0.1% - 5%.

9. The application of the azobenzene calixarene porous organic polymer as a solid-phase extraction agent in extracting triphenylmethane dyes in foods according to claim 6, characterized in that: The eluent is a mixed solution of acetonitrile and trifluoroacetic acid, and the volume ratio of the acid solution is 1%.

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