A boronic acid structure-based covalent organic framework material, a preparation method thereof and application thereof in dopamine detection

Abstract

The application relates to a covalent organic framework material based on a boronic acid structure and a preparation method and application thereof in dopamine detection, and relates to a covalent organic framework material and a preparation method and application thereof. The application aims to solve the technical problems of high detection limit and harsh recognition environment of the existing dopamine recognition method, and the periodical structure fragment of the covalent organic framework material based on the boronic acid structure is as follows: The covalent organic framework material based on the boronic acid structure is obtained by the reaction of 2-(4-boronic acid phenyl)-5,10-dinitro-1H-phenanthro[9,10-d]imidazole diamine and 4,4',4'',4'''-(pyrene-1,3,6,8-tetrayl) tetrakisbenzaldehyde. The covalent organic framework material based on the boronic acid structure is used for detecting dopamine, has strong selectivity and anti-interference capacity, and is not interfered by amino acids in the environment. The covalent organic framework material based on the boronic acid structure can be embedded in a hydrogel to facilitate carrying. The covalent organic framework material based on the boronic acid structure can be applied to the detection of dopamine in an environment and a biological system.

Description

Technical Field

[0001] This invention relates to a covalent organic framework (COF) material, its preparation method, and its application. Background Technology

[0002] Dopamine (DA) is an important neurotransmitter involved in regulating motor, mood, and cognitive functions. Abnormal dopamine levels are associated with various neurological disorders, such as Parkinson's disease, schizophrenia, and depression. Therefore, rapid and sensitive detection of dopamine is crucial for the early diagnosis and treatment of these diseases. Currently, methods for dopamine detection mainly include high-performance liquid chromatography (HPLC), electrochemical methods, and fluorescence methods. However, these methods typically require complex equipment and cumbersome sample pretreatment processes, making rapid on-site detection difficult. In recent years, hydrogel sensors based on functional materials have gradually become a research hotspot for dopamine detection due to their high sensitivity, ease of operation, and visual detection capabilities. Hydrogels, with their unique three-dimensional network structure, good biocompatibility, and tunable physicochemical properties, are considered ideal carriers for immobilizing fluorescent probes. Embedding fluorescent probes in a hydrogel network not only improves probe stability but also achieves high probe loading and uniform dispersion. By embedding boric acid-structured COF materials in hydrogels, not only can specific recognition of dopamine be achieved, but also the visual detection of dopamine can be realized through the swelling behavior of hydrogels.

[0003] Chinese patent application number 202311058644.1, entitled "Preparation of ZGC / ZIF-8-NH2 / Chitosan Hydrogel and its Application in Dopamine Detection," discloses a method. It is a Cr-doped... 3+ Zinc gallate persistent luminescent nanoparticles (ZGCPLNPs) were combined with amino-modified layered porous zeolite imidazole frameworks (ZIF-8-NH2) to obtain ZGC / ZIF-8-NH2 nanocomposites. Then, the ZGC / ZIF-8-NH2 nanocomposites were crosslinked with chitosan molecules to obtain ZGC / ZIF-8-NH2 / chitosan hydrogel. The detection limit of this hydrogel for dopamine detection was 1.0 mM, which is relatively high.

[0004] In their article "Optical Dual-Mode Detection of Dopamine Based on Fe(III)-Dopamine-Naphthyldiol Colorimetric Reaction" published in *Analytical Laboratory*, Zhao Lingzhi et al. developed a method for detecting dopamine using a simple, highly selective, and highly sensitive colorimetric-fluorescence dual-mode detection method. This method involves the oxidation of dopamine by Fe(III) followed by a reaction with 1,3-naphthyldiol to generate both colorimetric and fluorescent products. However, the reaction must be carried out in a liquid environment at pH 3.0, making the detection environment quite demanding.

[0005] According to current literature reports, fluorescent probes mainly have the following drawbacks:

[0006] 1. There are currently few reports on hydrogels recognizing dopamine;

[0007] 2. The fluorescence recognition environment for detecting dopamine is quite demanding. Summary of the Invention

[0008] This invention aims to address the technical problems of high detection limits and harsh recognition environments in existing dopamine recognition methods by providing a boric acid-based covalent organic framework (COF) material, its preparation method, and its application in dopamine detection. The boric acid-based COF material of this invention is prepared into an embedded hydrogel, which is used as a sensor for dopamine recognition. This sensor utilizes the specific dopamine recognition ability of the boric acid-based COF material, combined with the high permeability of the hydrogel and its high loading capacity for COF materials, to achieve highly sensitive and selective detection of dopamine.

[0009] The periodic structural segments of the covalent organic framework material based on boric acid structure of the present invention are as follows:

[0010] .

[0011] The aforementioned covalent organic framework material based on boric acid structure is obtained by reacting 2-(4-boronic acid phenyl)-5,10-dinitro-1H-phenanthro[9,10-d]imidazolium diamine (hereinafter collectively referred to as phenanthroimidazole-boronic acid diamine) and 4,4',4'',4'''-(pyrene-1,3,6,8-tetramethyl)tetrabenzaldehyde (hereinafter collectively referred to as pyrene tetraaldehyde), and the reaction formula is as follows:

[0012]

[0013] The above-mentioned method for preparing covalent organic framework materials based on boric acid structures is carried out according to the following steps:

[0014] I. Phenanthemidazole-borate diamine and pyrene tetraaldehyde are added to mixed solvent I according to a molar ratio of 1:(0.05~0.12). Then, the acid is added to mixed solvent I as a catalyst according to a molar ratio of 1:(0.01~0.10) of phenanthemidazole-borate diamine and pyrene tetraaldehyde. The mixture is mixed evenly to obtain reaction solution I.

[0015] 2. Add reaction solution I to the Schlenk tube and perform a vacuum-nitrogen purging cycle to maintain a nitrogen environment inside the Schlenk tube;

[0016] 3. Heat the Schlenk tube to 100~200℃ and react for 1~7 days;

[0017] IV. After the reaction is complete, the mixture is cooled to room temperature, filtered, and the filter cake is washed clean with organic solvent II. After vacuum drying, a covalent organic framework material based on boric acid structure is obtained.

[0018] Furthermore, the organic solvent I mentioned in step one is one or any combination of two of the following: mesitylene, o-dichlorobenzene, N,N-dimethylformamide, dioxane, and n-butanol.

[0019] Furthermore, the acid mentioned in step one is formic acid, acetic acid, trifluoroacetic acid, benzenesulfonic acid, p-toluenesulfonic acid, benzoic acid, concentrated hydrochloric acid with a mass percentage concentration of 30% to 37%, or concentrated sulfuric acid with a mass percentage concentration of 95% to 98%.

[0020] Furthermore, the synthesis method of phenanthrimidazole-boronic acid diamine described in step one is as follows:

[0021] (1) First, concentrated HNO3, concentrated H2SO4 and 9,10-phenanthrenequinone are reacted at 110~120℃ for 12~24 hours to obtain a pale yellow solid 2,7-dinitro-9,10-phenanthrenequinone;

[0022] (2) 2,7-dinitro-9,10-phenanthrenequinone, ammonium acetate and borate benzaldehyde are reacted at 110~120℃ for 6~12 hours to obtain 2-(4-boronic acid phenyl)-5,10-dinitro-1H-phenanthrene[9,10-d]imidazolium;

[0023] (3) Then, 2-(4-boronicophenyl)-5,10-dinitro-1H-phenanthro[9,10-d]imidazole and Raney nickel were added to a mixed solution of hydrazine hydrate and ethanol and reacted at 65-80°C for 3-6 hours to obtain phenanthroimidazole-boronic acid diamine. Its synthetic formula is as follows:

[0024]

[0025] The aforementioned application of covalent organic framework materials based on boric acid structures involves using these materials to detect dopamine.

[0026] The method for qualitative detection of dopamine using the above-mentioned covalent organic framework material based on boric acid structure is carried out according to the following steps:

[0027] I. The covalent organic framework material based on boric acid structure was prepared at a concentration of 3 × 10⁻⁶. -3 g·L -1 The probe solution A is obtained by uniformly dispersing it in methanol.

[0028] 2. Add the sample to be tested to probe solution A, mix thoroughly, and obtain test solution B;

[0029] III. Using 380 nm as the excitation wavelength, measure the fluorescence emission spectrum of probe solution A, and record the emission intensity at an emission wavelength of 565 nm, denoted as T. A ;

[0030] IV. Using 380 nm as the excitation wavelength, measure the fluorescence emission spectrum of the test solution B, and record the emission intensity at an emission wavelength of 565 nm, denoted as T. B ;

[0031] V. Comparison of T A and T B If T A >T B If the result is positive, the sample to be tested is determined to contain dopamine.

[0032] For convenient portable detection, boric acid-based covalent organic framework materials can be prepared into hydrogels. The method for preparing hydrogels for dopamine detection using boric acid-based covalent organic framework materials is as follows:

[0033] 1. Add 4-10 g of acrylamide (AAm), 0.2-0.6 g of sodium alginate, 0.004-0.006 g of N,N'-methylenebisacrylamide (MBA) and 0.2-0.4 g of ammonium persulfate (APS) to 20 mL of deionized water, stir well to obtain a hydrogel solution;

[0034] 2. Take 0.1~0.8 mg of covalent organic framework material based on boric acid structure and disperse it in 0.5 mL of deionized water, and sonicate for 30 minutes to obtain COF dispersion;

[0035] 3. Mix 0.5 mL of COF dispersion with 10 mL of hydrogel solution, stir well, pour into a mold, and place in a 50℃ oven for 4 hours to obtain a hydrogel for dopamine detection. A covalent organic framework material based on a boric acid structure is embedded in the hydrogel.

[0036] The method for qualitative detection of dopamine using the hydrogel described above is performed according to the following steps:

[0037] 1. Irradiate the hydrogel used to detect dopamine with a UV lamp and take a color photograph. Then extract the RGB values ​​of the photograph and record them as R1, G1, and B1.

[0038] 2. Immerse the hydrogel used to detect dopamine in the test solution, irradiate it with ultraviolet light and take a color photograph, then extract the RGB values ​​of the photograph and record them as R2, G2, B2;

[0039] 3. Compare R1 and R2. If R1 > R2, then the test solution contains dopamine.

[0040] Alternatively, compare G1 and G2. If G1 > G2, then the test solution contains dopamine.

[0041] Or compare and ,like If the test solution contains dopamine, then it is determined that the solution contains dopamine.

[0042] The covalent organic framework material based on boric acid structure of this invention exhibits strong selectivity and anti-interference ability for dopamine as a fluorescent probe. It can recognize dopamine without being affected by environmental amino acids such as L-isoleucine, L-lactamase, L-histidine, L-cysteine, α-D-glucose, lactose, galactose, D-glucose, sucrose, and fructose. The detection limit is as low as 8.5 μM.

[0043] The method for detecting dopamine using the boric acid-based covalent organic framework material of the present invention is simple and has a rapid response. During the test, the boric acid-based covalent organic framework material can maintain a stable fluorescence intensity, indicating that it has good chemical stability and its recognition is not affected by the external environment.

[0044] Compared with other fluorescent probes, the covalent organic framework material based on boric acid structure of the present invention can be used as a fluorescent probe for the detection of dopamine in environmental and biological systems, thus expanding the scope and application fields of covalent organic frameworks. Attached Figure Description

[0045] Figure 1 This is the infrared spectrum of the covalent organic framework material based on boric acid structure prepared in Example 1. The horizontal axis represents wavelength, and the vertical axis represents transmittance.

[0046] Figure 2 The fluorescence spectrum of the covalent organic framework material based on boric acid structure prepared in Example 1 is shown.

[0047] Figure 3 This is a covalent organic framework material based on boric acid structure prepared in Example 1 (3×10⁻⁶). -3 g·L -1 Add different types of amino acids, add 1.2 × 10 -4 mol·L -1 The fluorescence spectrum after DA is shown, with wavelength on the horizontal axis and fluorescence intensity on the vertical axis.

[0048] Figure 4 This is a covalent organic framework material based on boric acid structure prepared in Example 1 (3×10⁻⁶). -3 g·L-1 ) with different types of amino acids and 1.2×10 -4 mol·L -1 The fluorescence spectrum of DA coexisting, with wavelength on the horizontal axis and fluorescence intensity on the vertical axis.

[0049] Figure 5 This is a covalent organic framework material based on boric acid structure prepared in Example 1 (3×10⁻⁶). -3 g·L -1 Fluorescence spectra of DA with different concentrations, with wavelength on the horizontal axis and fluorescence intensity on the vertical axis.

[0050] Figure 6 This is a covalent organic framework material based on boric acid structure prepared in Example 1 (3×10⁻⁶). -3 g·L -1 Linear fitting graph of fluorescence intensity when coexisting with different concentrations of DA, with the horizontal axis representing DA concentration and the vertical axis representing fluorescence intensity.

[0051] Figure 7 The hydrogel prepared in Example 1 for detecting dopamine was immersed in a solution with a concentration of 0.1–1.0 mmol·L⁻¹. -1 Photograph taken under a 365 nm UV lamp after incubation in a dopamine solution for 20 minutes.

[0052] Figure 8 The hydrogel prepared in Example 1 for detecting dopamine was used to extract the RGB values ​​as a function of concentration by taking a color photo with a smartphone after dopamine was detected. The horizontal axis represents the dopamine concentration and the vertical axis represents the R / G / B values.

[0053] Figure 9 The graph shows the linear relationship between the R (red channel) value and concentration of the hydrogel prepared in Example 1 for detecting dopamine after identifying dopamine by taking a color photo with a smartphone. The horizontal axis represents the dopamine concentration and the vertical axis represents the R (red channel) value. Detailed Implementation

[0054] The beneficial effects of the present invention are verified using the following examples:

[0055] Example 1: The preparation method of the covalent organic framework material based on boric acid structure in this example is carried out according to the following steps:

[0056] 1. Add 0.04 mol of phenanthrimidazole-borate diamine and 0.004 mol of pyrene tetraaldehyde to mixed solvent I, which is composed of 1.8 mL of o-dichlorobenzene and 0.2 mL of n-butanol. Then add 0.004 mol of glacial acetic acid as a catalyst to mixed solvent I and mix well to obtain reaction solution I.

[0057] The method for synthesizing the phenanthrimidazole-borate diamine is as follows:

[0058] (1) First, 60 ml of concentrated HNO3 with a mass percentage of 63%, 8 ml of concentrated H2SO4 with a mass percentage of 98%, and 0.03 mol of 9,10-phenanthrenequinone were reacted at 120℃ for 24 hours to obtain a pale yellow solid 2,7-dinitro-9,10-phenanthrenequinone;

[0059] (2) Then add 0.003 mol of 2,7-dinitro-9,10-phenanthrenequinone, 0.012 mol of ammonium acetate and 0.0045 mol of borate benzaldehyde into a three-necked flask and react at 120°C for 6 hours to obtain 2-(4-boronic acid phenyl)-5,10-dinitro-1H-phenanthrene[9,10-d]imidazolium;

[0060] (3) Add 0.0005 mol of 2-(4-boronic acid phenyl)-5,10-dinitro-1H-phenanthro[9,10-d]imidazole and 0.9 g of Raney nickel to a mixed solution of 7.5 ml hydrazine hydrate and 10 ml ethanol, and react at 80 °C for 4 hours to obtain phenanthroimidazole-boronic acid diamine;

[0061] 2. Add reaction solution I to the Schlenk tube and perform a vacuum-nitrogen purging cycle to maintain a nitrogen environment inside the Schlenk tube;

[0062] 3. Heat the Schlenk tube to 110°C and react for 2 days;

[0063] IV. After the reaction was completed, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II containing acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a covalent organic framework material based on boric acid structure was obtained with a yield of 62%.

[0064] The structure of the covalent organic framework material based on boric acid prepared in Example 1 was characterized by Fourier transform infrared spectroscopy, and the infrared spectrum obtained is as follows: Figure 1 As shown. From Figure 1 It can be seen that at 1600 cm -1 The presence of characteristic absorption peaks for C=N at these locations indicates the successful preparation of the covalent organic framework material. The characterization results above show that the periodic structural segments of the boric acid-based covalent organic framework material prepared in this embodiment are:

[0065] .

[0066] The spectroscopic properties of the covalent organic framework material based on boric acid structure prepared in Example 1 were tested as follows:

[0067] I. Solution Preparation

[0068] Weigh 3.0 mg of the boric acid-based covalent organic framework material prepared in Example 1 and add it to a 100 mL volumetric flask, then dilute to volume with methanol to prepare a solution with a concentration of 0.03 g·L⁻¹. -1 The stock solution;

[0069] Different masses of amino acids (L-isoleucine, L-lactamase, L-histidine, L-cysteine, α-D-glucose, lactose, galactose, D-glucose, sucrose, and fructose) were weighed and added to 10 mL volumetric flasks, diluted to volume with deionized water, and sonicated until completely dissolved, yielding a concentration of 1.0 × 10⁻⁶. -4 mol·L -1 Different types of amino acid stock solutions;

[0070] Weigh 0.948 mg of dopamine hydrochloride, dissolve it in deionized water, transfer it to a 50 mL volumetric flask and make up to volume. Mix well and store in the dark at 3-5°C.

[0071] II. Spectral performance testing:

[0072] To 3×10 -3 g·L -1 Add 1.0 × 10 to probe solution A -4 mol·L -1 Different types of amino acid stock solutions were ultrasonically vibrated for 30 min to obtain a mixed solution;

[0073] Using 380 nm as the excitation wavelength, measurements were taken at 3 × 10⁻⁶ nm. -3 g·L -1 Add 1.0 × 10 to probe solution A. -4 mol·L -1 Fluorescence emission spectra of mixed solutions of different types of amino acid stock solutions and mixed solutions with added dopamine stock solution were obtained, and the results are as follows: Figure 2 , Figure 3 and Figure 4 As shown.

[0074] Figure 2 The fluorescence spectrum of the covalent organic framework material based on boric acid structure prepared in Example 1 is shown. Figure 2 It can be seen that the fluorescence emission wavelength of probe solution A prepared in this embodiment is 565 nm and the fluorescence intensity is 380 au.

[0075] Figure 3 This is a covalent organic framework material based on boric acid structure prepared in Example 1 (3×10⁻⁶). -3 g·L-1 Add different types of amino acids, add 1.2 × 10 -4 mol·L -1 The fluorescence spectrum after DA is shown, with wavelength on the x-axis and fluorescence intensity on the y-axis. From Figure 3 It can be seen that adding different types of amino acid stock solutions to probe solution A did not significantly change the fluorescence intensity of probe solution A, which remained between 320 au and 400 au. However, adding 1.0 × 10⁻⁶ amino acid stock solutions to probe solution A did not change the fluorescence intensity. - 4 mol·L -1 After being treated with DA stock solution, the emission wavelength intensity decreased significantly to 190 au, with a quenching degree of approximately 2 times. Therefore, the fluorescence emission spectrum shows that the covalent organic framework material based on boric acid structure prepared in Example 1 has selective recognition performance for DA.

[0076] The probe solution A of Example 1 was tested for its resistance to interference from different types of amino acids during DA detection. The specific test method is as follows: [The following text appears to be a separate, unrelated section:] 3×10 -3 g·L -1 Add 1.0 × 10 to probe solution A -4 mol·L -1 Shake the different types of amino acids well, then add 1.0 × 10⁻⁶. -4 mol·L -1 The DA stock solution was used to prepare a mixed test solution containing the probe, recognition substance, and interfering substance. After thorough mixing, the solution was sonicated for 30 minutes before fluorescence testing. Figure 4 This is a covalent organic framework material based on boric acid structure prepared in Example 1 (3×10⁻⁶). -3 g·L -1 ) with different types of amino acids and 1.2×10 -4 mol·L -1 The fluorescence spectrum of DA coexistence is shown, with wavelength on the x-axis and fluorescence intensity on the y-axis. From Figure 4 As can be seen from the fluorescence spectrum, when DA coexists with different types of amino acids, the fluorescence intensity of probe solution A decreases. Therefore, it can be inferred from the fluorescence spectrum that the fluorescence detection of DA by the covalent organic framework material based on boric acid structure prepared in Example 1 is not affected by different types of amino acids.

[0077] The test method for the responsiveness of probe solution A in Example 1 to different DA concentrations is as follows: [The text then abruptly shifts to a seemingly unrelated topic about a DA concentration and a test method involving 3×10...] -3 g·L -1 Add 0~1.0×10 to probe solution A -4 mol·L -1Different concentrations of DA stock solutions were prepared. After thorough mixing and ultrasonic agitation for 30 min, fluorescence testing was performed. Figure 5 This is a covalent organic framework material based on boric acid structure prepared in Example 1 (3×10⁻⁶). -3 g·L -1 Fluorescence spectra of DA coexisting with different concentrations, with wavelength on the x-axis and fluorescence intensity on the y-axis. Figure 5 As can be seen, the fluorescence intensity at the emission wavelength of 565 nm decreases with the increase of DA concentration. Figure 6 This is a covalent organic framework material based on boric acid structure prepared in Example 1 (3×10⁻⁶). -3 g·L -1 Linear fitting plot of fluorescence intensity when DA coexists with different concentrations of DA, with the x-axis representing DA concentration and the y-axis representing fluorescence intensity. Figure 6 It can be seen that the fluorescence emission intensity is linearly correlated with the DA concentration, and the linear equation is y = -2.269[DA] + 384.563, R0 2 =0.998, with a linear range of 0~100 μM.

[0078] To facilitate portable detection, a hydrogel for dopamine detection was prepared using the covalent organic framework material based on boric acid structure prepared in Example 1. The specific method is as follows:

[0079] 1. Add 4 g of acrylamide (AAm), 0.2 g of sodium alginate, 0.004 g of N,N'-methylenebisacrylamide (MBA) and 0.2 g of ammonium persulfate (APS) to 20 mL of deionized water and stir until homogeneous to obtain a hydrogel solution.

[0080] 2. Take 0.1 mg of covalent organic framework material based on boric acid structure and disperse it in 0.5 mL of deionized water, and sonicate for 30 minutes to obtain COF dispersion;

[0081] 3. Mix 0.5 mL of COF dispersion with 10 mL of hydrogel solution, stir well, pour into a mold, and place in a 50℃ oven for 4 hours to obtain a hydrogel for dopamine detection. A covalent organic framework material based on a boric acid structure is embedded in the hydrogel.

[0082] The recognition performance of the hydrogel used to detect dopamine for DA was tested using the following method: The hydrogel used to detect dopamine was immersed in an atmosphere with a concentration of 0.1–1.0 mmol·L⁻¹. -1 Incubate in a dopamine solution for 20 minutes, remove and dry, irradiate under a 365 nm UV lamp, and take a color photo with a smartphone. Figure 7 As shown, the RGB values ​​of the photo are extracted as follows. Figure 8 As shown in the figure, it can be seen that when the dopamine concentration decreases regularly from 0.0 to 1.0 mM, the red and green values ​​show a linear relationship with the dopamine concentration, as shown in the figure. Figure 9 As shown, the hydrogel has the ability to recognize dopamine, with a detection limit of 0.049 mM.

[0083] Example 2: The preparation method of the covalent organic framework material based on boric acid structure in this example is carried out according to the following steps:

[0084] 1. Add 0.06 mol of phenanthrimidazole-borate diamine and 0.04 mol of pyrene tetraaldehyde to a mixed solvent I consisting of 1.6 mL of o-dichlorobenzene and 0.4 mL of n-butanol. Then add 0.003 mol of glacial acetic acid as a catalyst to the mixed solvent I and mix thoroughly to obtain reaction solution I. The synthesis method of phenanthrimidazole-borate diamine is the same as that in Example 1.

[0085] 2. Add reaction solution I to the Schlenk tube and perform a vacuum-nitrogen purging cycle to maintain a nitrogen environment inside the Schlenk tube;

[0086] 3. Heat the Schlenk tube to 120°C and react for 3 days;

[0087] IV. After the reaction was completed, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II containing acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a covalent organic framework material based on boric acid structure was obtained with a yield of 60%.

[0088] Example 3: The preparation method of the covalent organic framework material based on boric acid structure in this example is carried out according to the following steps:

[0089] 1. Add 0.08 mol of phenanthrimidazole-borate diamine and 0.04 mol of pyrenetetraldehyde to a mixed solvent I consisting of 1.4 mL of o-dichlorobenzene and 0.6 mL of n-butanol. Then add 0.008 mol of benzenesulfonic acid as a catalyst to the mixed solvent I and mix thoroughly to obtain reaction solution I. The synthesis method of phenanthrimidazole-borate diamine is the same as that in Example 1.

[0090] 2. Add reaction solution I to the Schlenk tube and perform a vacuum-nitrogen purging cycle to maintain a nitrogen environment inside the Schlenk tube;

[0091] 3. Heat the Schlenk tube to 130°C and maintain the temperature for 3 days to carry out the reaction;

[0092] IV. After the reaction was completed, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II containing acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a covalent organic framework material based on boric acid structure was obtained with a yield of 68%.

[0093] Example 4: The preparation method of the covalent organic framework material based on boric acid structure in this example is carried out according to the following steps:

[0094] 1. Add 0.10 mol of phenanthrimidazole-borate diamine and 0.04 mol of pyrenetetraldehyde to a mixed solvent I consisting of 0.8 mL of o-dichlorobenzene and 1.2 mL of n-butanol. Then add 0.005 mol of formic acid as a catalyst to the mixed solvent I and mix thoroughly to obtain reaction solution I. The synthesis method of the phenanthrimidazole-borate diamine is the same as that in Example 1.

[0095] 2. Add reaction solution I to the Schlenk tube and perform a vacuum-nitrogen purging cycle to maintain a nitrogen environment inside the Schlenk tube;

[0096] 3. Heat the Schlenk tube to 170°C and maintain the temperature for 5 days to carry out the reaction;

[0097] IV. After the reaction was completed, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II containing acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a covalent organic framework material based on boric acid structure was obtained with a yield of 59%.

[0098] Example 5: The preparation method of the covalent organic framework material based on boric acid structure in this example is carried out according to the following steps:

[0099] 1. 0.16 mol of phenanthrimidazole-borate diamine and 0.04 mol of pyrene tetraaldehyde were added to a mixed solvent I consisting of 0.6 mL of o-dichlorobenzene and 1.4 mL of n-butanol. Then, 0.016 mol of benzoic acid was added to the mixed solvent I as a catalyst. The mixture was stirred until homogeneous to obtain reaction solution I. The synthesis method of the phenanthrimidazole-borate diamine was the same as that in Example 1.

[0100] 2. Add reaction solution I to the Schlenk tube and perform a vacuum-nitrogen purging cycle to maintain a nitrogen environment inside the Schlenk tube;

[0101] 3. Heat the Schlenk tube to 180°C and maintain the temperature for 6 days to carry out the reaction;

[0102] IV. After the reaction was completed, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II containing acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a covalent organic framework material based on boric acid structure was obtained with a yield of 43%.

Claims

1. A covalent organic framework material based on a boric acid structure, characterized in that, The periodic structural segments of this material are: 。 2. A method for preparing a covalent organic framework material based on a boric acid structure as described in claim 1, characterized in that, This method is performed in the following steps: I. Phenanthemidazole-borate diamine and pyrene tetraaldehyde are added to mixed solvent I at a molar ratio of 1:(0.05~0.12). Then, the acid is added to mixed solvent I as a catalyst at a molar ratio of 1:(0.01~0.10) between phenanthemidazole-borate diamine and acid. The mixture is stirred until homogeneous to obtain reaction solution I. The phenanthemidazole-borate diamine is 2-(4-boronic acid phenyl)-5,10-dinitro-1H-phenanthemid[9,10-d]imidazolium diamine, and the pyrene tetraaldehyde is 4,4',4'',4'''-(pyrene-1,3,6,8-tetramethyl)tetrabenzaldehyde.

2. Add reaction solution I to the Schlenk tube and perform a vacuum-nitrogen purging cycle to maintain a nitrogen environment inside the Schlenk tube; 3. Heat the Schlenk tube to 100~200℃ and react for 1~7 days; IV. After the reaction is complete, the mixture is cooled to room temperature, filtered, and the filter cake is washed clean with organic solvent II. After vacuum drying, a covalent organic framework material based on boric acid structure is obtained.

3. The method for preparing a covalent organic framework material based on a boric acid structure according to claim 2, characterized in that, The mixed solvent I mentioned in step one is any combination of two of the following: mesitylene, o-dichlorobenzene, N,N-dimethylformamide, dioxane, and n-butanol.

4. A method for preparing a covalent organic framework material based on a boric acid structure according to claim 2 or 3, characterized in that, The acid mentioned in step one is formic acid, acetic acid, trifluoroacetic acid, benzenesulfonic acid, p-toluenesulfonic acid, benzoic acid, or concentrated hydrochloric acid with a mass percentage concentration of 30% to 37%.

5. A method for preparing a covalent organic framework material based on a boric acid structure according to claim 2 or 3, characterized in that, The synthesis method of phenanthrimidazole-boronic acid diamine described in step one is as follows: (1) First, concentrated HNO3, concentrated H2SO4 and 9,10-phenanthrenequinone are reacted at 110~120℃ for 12~24 hours to obtain a pale yellow solid 2,7-dinitro-9,10-phenanthrenequinone; (2) 2,7-dinitro-9,10-phenanthrenequinone, ammonium acetate and borate benzaldehyde are reacted at 110~120℃ for 6~12 hours to obtain 2-(4-boronic acid phenyl)-5,10-dinitro-1H-phenanthrene[9,10-d]imidazolium; (3) Then add 2-(4-boronic acid phenyl)-5,10-dinitro-1H-phenanthro[9,10-d]imidazole and Raney nickel to a mixed solution of hydrazine hydrate and ethanol and react at 65~80℃ for 3~6 hours to obtain phenanthroimidazole-boronic acid diamine.

6. The application of the covalent organic framework material based on boric acid structure as described in claim 1, characterized in that, This application uses covalent organic framework materials based on boric acid structures to detect dopamine.

7. The application of a covalent organic framework material based on a boric acid structure according to claim 6, characterized in that, A method for preparing hydrogels for dopamine detection using boric acid-based covalent organic framework materials is performed according to the following steps:

1. Add 4-10 g of acrylamide, 0.2-0.6 g of sodium alginate, 0.004-0.006 g of N,N'-methylenebisacrylamide and 0.2-0.4 g of ammonium persulfate to 40 mL of deionized water, stir well to obtain a hydrogel solution; 2. Take 0.1~0.8 mg of covalent organic framework material based on boric acid structure and disperse it in 0.5 mL of deionized water, and sonicate for 30 minutes to obtain COF dispersion; 3. Mix 0.5 mL of COF dispersion with 10 mL of hydrogel solution, stir well and pour into a mold, place in an oven at 50℃ for 4 hours to obtain a hydrogel for dopamine detection.

8. The method for qualitative detection of dopamine using the hydrogel for dopamine detection according to claim 7 is performed according to the following steps:

1. Irradiate the hydrogel used to detect dopamine with a UV lamp and take a color photograph. Then extract the RGB values ​​of the photograph and record them as R1, G1, and B1.

2. Immerse the hydrogel used to detect dopamine in the test solution, irradiate it with ultraviolet light and take a color photograph, then extract the RGB values ​​of the photograph and record them as R2, G2, and B2; 3. Compare R1 and R2. If R1 > R2, then the test solution contains dopamine. Alternatively, compare G1 and G2. If G1 > G2, then the test solution contains dopamine. Or compare and ,like If the test solution contains dopamine, then it is determined that the solution contains dopamine.

Images