Fluorescent covalent organic framework material for hydrogen sulfide detection as well as preparation method and application of fluorescent covalent organic framework material

Abstract

The invention discloses a fluorescent covalent organic framework material for hydrogen sulfide detection as well as a preparation method and application thereof, relates to a covalent organic framework material as well as a preparation method and application thereof, and aims to solve the technical problems that an existing porous material for H2S detection is few in structure type, unstable in COFs (Covalent Organic Frameworks) structure, high in detection limit and harsh in detection environment. The periodic structure fragment of the fluorescent covalent organic framework material for hydrogen sulfide detection is shown in the specification. 3-(5, 10-diamino-1H-phenanthrene) [9, 10-d] imidazole-2-yl) phenol and 2, 4, 6-tri (4-formylphenoxy)-1, 3, 5-triazine are subjected to a reaction to obtain a hydroxyl intermediate, the hydroxyl intermediate is modified with 2, 4-dinitrofluorobenzene, and the fluorescent material is used for qualitative detection of H2S. The method is not interfered by amino acids and anions in the environment, and is not influenced by an acid-base environment. The method can be used in the field of H2S detection.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen sulfide (H2S) detection, and in particular relates to a fluorescent covalent organic framework material and a preparation method and application thereof. Background Art

[0002] H2S, a highly toxic and flammable acidic gas, is widely present in natural gas extraction, oil refining, wastewater treatment, and biological metabolism. Exposure to low concentrations can cause central nervous system damage in humans, while inhalation of high concentrations can cause sudden death. The threshold limit value (TLV) for H2S in industrial environments is typically below 10 ppm, while the physiological concentration range of H2S in organisms is only nanomolar to micromolar (50-160 μM). Therefore, the development of highly sensitive and selective H2S detection technologies is of great significance for industrial safety and protection, environmental monitoring, and biomedical research. Traditional H2S detection methods primarily include electrochemical sensors, metal oxide semiconductors, and chromatography, but these technologies generally suffer from expensive equipment, complex operation, or slow response speeds. Fluorescent probe technology has become a research hotspot due to its advantages such as high sensitivity, real-time response, and visual detection. However, existing small molecule fluorescent probes (such as those based on azide or nitro reduction) often suffer from poor photostability, low water solubility, and non-recyclability. Zhou Liyi et al. reported in Spectrochomoca Acta Part A: Molecular Spectroscopy, December 2024, Vol. 323, an azide-based fluorescent probe, CIT-H2S, for H2S detection. The azide group reacts with H2S and is reduced to an amino group, eliminating ICT quenching and achieving a fluorescence "on" response. However, the azide group is susceptible to photolysis and requires light-protection, limiting its application for long-term imaging. Furthermore, while porous materials (such as metal organic frameworks (MOFs)) can be loaded with fluorophores for H2S detection, their frameworks are unstable and prone to decomposition, particularly in acidic or humid environments, severely limiting their practical applications.

[0003] Covalent organic frameworks (COFs) are a class of crystalline porous materials formed by lightweight elements connected by strong covalent bonds. They have high specific surface area, tunable pore size, and excellent chemical stability. In recent years, functional materials with fluorescence response have been constructed by embedding fluorescent groups (such as pyrene, triphenylamine, or borate) into the COFs skeleton. This type of material not only inherits the structural designability of COFs, but also can achieve switching or shifting of fluorescence signals through the selective reaction of H2S with specific sites within the framework (such as double bonds, borate esters, or metal coordination sites). Compared with traditional probes, fluorescent COFs combine high stability, recyclability, and signal amplification effects, providing a new approach for the development of a new generation of H2S sensors. In recent years, researchers have attempted to combine COFs with H2S-responsive groups, but still face challenges such as insufficient stability or anti-interference. Yin Xia et al. reported in Chem. Sci., Vol. 9, No. 44, pp. 8402-28408, November 2018, that an azide-based covalent organic framework was used for H2S detection. The azide unit was reduced to an amino group in the presence of H2S, thereby enhancing fluorescence emission. However, this probe relies on the H2S dissociation reaction. + The protonation of nitrogen atoms in the COF backbone may cause failure outside the physiological pH range (7.0-7.4), limiting its application in acidic or alkaline environments.

[0004] According to current literature reports, the main defects of H2S identification methods are as follows:

[0005] 1. There are only a few types of porous material structures used for H2S detection;

[0006] 2. Existing fluorescent COFs for H2S detection have a single structure;

[0007] 3. The existing fluorescent COF used for H2S detection has an unstable structure, a high detection limit, and a harsh detection environment. Summary of the Invention

[0008] The present invention aims to solve the technical problems of the limited variety of porous material structures used for H2S detection, the unstable structure of fluorescent COFs used for H2S detection, the high detection limit, and the harsh detection environment. The present invention provides a fluorescent covalent organic framework material for H2S detection and its preparation method and application. This fluorescent covalent organic framework material for hydrogen sulfide detection has a novel structure, is easy to modify, has good stability, and high selectivity, and can realize its qualitative detection of H2S.

[0009] The fluorescent covalent organic framework material for hydrogen sulfide detection of the present invention has a periodic structural fragment as follows:

[0010] .

[0011] The fluorescent covalent organic framework material for hydrogen sulfide detection is prepared by reacting 3-(5,10-diamino-1H-phenanthrene)[9,10-d]imidazol-2-yl)phenol (hereinafter collectively referred to as phenanthroimidazole-hydroxy monomer) and 2,4,6-tris(4-formylphenoxy)-1,3,5-triazine (hereinafter collectively referred to as triazine aldehyde monomer) to obtain a hydroxy intermediate. The reaction formula is:

[0012] .

[0013] The hydroxy intermediate was then post-modified with 2,4-dinitrofluorobenzene to obtain a fluorescent covalent organic framework material for H2S detection. The reaction formula is:

[0014] .

[0015] The preparation method of the fluorescent covalent organic framework material for hydrogen sulfide detection is specifically carried out according to the following steps:

[0016] 1. adding the phenanthroimidazole-hydroxy monomer and the triazine aldehyde monomer to a mixed solvent I at a molar ratio of 1 to 5:1, then adding the acid as a catalyst to the mixed solvent I at a molar ratio of 1 to 0.01 to 0.1, and mixing the mixture to obtain a reaction solution I;

[0017] 2. Add reaction solution I into the Schlenk tube, and perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen atmosphere in the Schlenk tube;

[0018] 3. Raise the temperature of the Schlenk tube to 100-200°C and maintain for 1-7 days to carry out the reaction;

[0019] 4. After the reaction is completed, the temperature is lowered to room temperature, filtered, and the filter cake is washed clean with mixed solvent II and vacuum dried to obtain a hydroxy intermediate;

[0020] 5. Add the hydroxy intermediate and 2,4-dinitrofluorobenzene to an organic solvent at a ratio of (20-400) mg to 1 mmol, then add a base to provide an alkaline environment and promote the reaction, and react at room temperature for 6-24 hours.

[0021] 6. After the reaction is completed, the filter cake is filtered and washed with mixed solvent II. After vacuum drying, a fluorescent covalent organic framework material for hydrogen sulfide detection is obtained.

[0022] Further, the synthesis method of the phenanthroimidazole-hydroxyl monomer in step one is as follows:

[0023] (1) first, 9,10-phenanthrenequinone is added to the mixed solution of concentrated HNO3 and concentrated H2SO4, and the temperature is raised to 120°C for reaction for 24 hours to obtain light yellow solid 2,7-dinitro-9,10-phenanthrenequinone;

[0024] (2) then, 2,7-dinitro-9,10-phenanthrenequinone, ammonium acetate and m-hydroxybenzaldehyde are mixed in a molar ratio of 1: (1~5): (1~5), and the reaction is carried out at 80°C for 6~12 hours to obtain 3-(5,10-dinitro-1H-phenanthrene) [9,10-d] imidazole-2-yl) phenol;

[0025] (3) then, 3-(5,10-dinitro-1H-phenanthrene) [9,10-d] imidazole-2-yl) phenol is added to a mixed solution of hydrazine hydrate and ethanol, and Raney nickel is added as a catalyst, and the reaction is carried out at 80°C for 3~12 hours to obtain a phenanthroimidazole-hydroxyl monomer.

[0026] The chemical reaction formula of the synthesis of the phenanthroimidazole-hydroxyl monomer is as follows:

[0027]

[0028] Further, the mixed solvent I in step one is any two of xylene, mesitylene, o-dichlorobenzene, N,N-dimethylformamide, dioxane and n-butanol.

[0029] Further, the acid in step one is glacial acetic acid, trifluoroacetic acid, benzene sulfonic acid, p-toluenesulfonic acid, benzoic acid, concentrated hydrochloric acid with a mass percentage concentration of 30%~37%, or concentrated sulfuric acid with a mass percentage concentration of 95%~98%.

[0030] Further, the molar ratio of the acid to the phenanthroimidazole-hydroxyl monomer in step one is (0.05~0.12):1.

[0031] Further, the mixed solvent II in step four and step six is any two of tetrahydrofuran, methanol, ethanol, ethyl acetate, acetone, dichloromethane, chloroform or 1,2-dichloroethane.

[0032] Further, the organic solvent in step five is dichloromethane, tetrahydrofuran, acetone, methanol, ethanol or N, N-dimethylformamide.

[0033] Further, the base in step five is triethylamine, potassium carbonate, sodium carbonate, calcium hydroxide or pyridine.

[0034] Furthermore, the alkaline environment described in step 5 refers to a pH value of 8 to 12.

[0035] The application of the fluorescent covalent organic framework material for hydrogen sulfide detection is to use it as a fluorescent material for the qualitative detection of H2S.

[0036] The method for qualitative detection of H2S using the fluorescent covalent organic framework material for H2S detection is carried out in the following steps:

[0037] First, the fluorescent covalent organic framework material for hydrogen sulfide detection was uniformly dispersed in a mixture of PBS buffer solution (pH = 7.4) and N, N-dimethylformamide (volume ratio: 3:(1-7)) to obtain probe solution A. The concentration of the fluorescent covalent organic framework material for H2S detection in probe solution A was 0.01-0.1 g·L -1 ;

[0038] 2. Add the sample I to the probe solution A and mix evenly to obtain the test solution B;

[0039] 3. Measure the fluorescence emission spectrum of probe solution A with an excitation wavelength of 320 nm and record the emission intensity at an emission wavelength of 424 nm, which is recorded as T A ;

[0040] 4. Measure the fluorescence emission spectrum of solution B with an excitation wavelength of 320 nm and record the emission intensity at a wavelength of 466 nm, which is recorded as T B ;

[0041] 5. Comparison T A and T B , if T A >T B , it is determined that the sample to be tested contains H2S.

[0042] The fluorescent covalent organic framework material of the present invention exhibits strong selectivity and anti-interference ability for H2S as a fluorescent probe, capable of identifying H2S without interference from amino acids and anions in the environment, such as glutathione, histidine, alanine, arginine, aspartic acid, glutamic acid, cysteine, glycine, leucine, methionine, phenylalanine, proline, serine, tryptophan, tyrosine, valine, and iodide, bromide, chloride, fluoride, bisulfate, sulfate, sulfite, bicarbonate, carbonate, nitrate, nitrite, hydrogen phosphate, thiocyanate, and acetate. Furthermore, the material is unaffected by acidic or alkaline environments. Compared to other fluorescent probes, the fluorescent covalent organic framework material of the present invention can be used as a fluorescent probe for detecting H2S in environmental and biological systems, expanding the scope and application of covalent organic frameworks. The method for detecting H2S using the fluorescent covalent organic framework material of the present invention is simple and has a rapid response. During the test process, the fluorescent 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is an infrared spectrum of the fluorescent covalent organic framework material for H2S detection prepared in Example 1, where the abscissa is wavelength and the ordinate is transmittance;

[0044] Figure 2 This is a high-resolution spectrum of the fluorescent covalent organic framework material N 1s for H2S detection prepared in Example 1;

[0045] Figure 3 This is a fluorescence spectrum of the fluorescent covalent organic framework material for H2S detection prepared in Example 1;

[0046] Figure 4 The fluorescent covalent organic framework material for H2S detection prepared in Example 1 was added with different types of amino acids and anions, and 0.001 mol·L -1 The fluorescence spectrum after H2S is added, the horizontal axis is the wavelength and the vertical axis is the fluorescence intensity;

[0047] Figure 5 This is a fluorescence spectrum of the fluorescent covalent organic framework material for H2S detection prepared in Example 1 when it coexists with different types of amino acids and anions and H2S. The horizontal axis is wavelength and the vertical axis is fluorescence intensity.

[0048] Figure 6 This is a graph of the fluorescence intensity of the fluorescent covalent organic framework material for H2S detection prepared in Example 1 when coexisting with H2S under different pH conditions, with the horizontal axis representing pH value and the vertical axis representing fluorescence intensity;

[0049] Figure 7 : This is a fluorescence spectrum of the fluorescent covalent organic framework material for H2S detection prepared in Example 1 when it coexists with H2S at different concentrations, with the horizontal axis representing wavelength and the vertical axis representing fluorescence intensity;

[0050] Figure 8 This is a linear fitting graph of the fluorescence intensity of the fluorescent covalent organic framework material for H2S detection prepared in Example 1 when it coexists with H2S at different concentrations, with the abscissa being the H2S concentration and the ordinate being the fluorescence intensity. DETAILED DESCRIPTION

[0051] The beneficial effects of the present invention are verified by the following examples:

[0052] Example 1: The preparation method of the fluorescent covalent organic framework material for H2S detection in this example is carried out according to the following steps:

[0053] 1. To a mixed solvent I of 1.8 mL of mesitylene and 0.2 mL of n-butanol, 0.04 mol of phenanthroimidazole-hydroxy monomer and 0.04 mol of triazine aldehyde monomer were added, respectively, and 0.004 mol of glacial acetic acid was added as a catalyst, and the mixture was mixed to obtain a reaction solution I.

[0054] The phenanthroimidazole-hydroxy monomer is synthesized according to the following steps:

[0055] (1) First, 6 g of 9,10-phenanthrenequinone was added to a mixture of 60 mL of 63% concentrated HNO3 and 8 mL of 98% concentrated H2SO4, and the mixture was heated to 120°C and reacted for 24 hours to obtain a light yellow solid 2,7-dinitro-9,10-phenanthrenequinone.

[0056] (2) 3 g of 2,7-dinitro-9,10-phenanthrenequinone, 1.5 g of ammonium acetate and 1.2 g of m-hydroxybenzaldehyde were mixed and reacted at 80 °C for 12 hours to obtain 3-(5,10-dinitro-1H-phenanthrene)[9,10-d]imidazol-2-yl)phenol;

[0057] (3) Then, 1.6 g of 3-(5,10-dinitro-1H-phenanthrene)[9,10-d]imidazol-2-yl)phenol was added to a mixed solution of 60 mL of hydrazine hydrate and 100 mL of ethanol, and 7.2 g of Raney nickel was added as a catalyst. The mixture was reacted at 80 °C for 6 hours under nitrogen protection to obtain a phenanthroimidazole-hydroxy monomer.

[0058] 2. Add reaction solution I into the Schlenk tube, and then perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen environment in the Schlenk tube;

[0059] 3. Raise the temperature of the Schlenk tube to 110°C and maintain for 2 days to carry out the reaction;

[0060] 4. After the reaction, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II of acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a hydroxy intermediate was obtained with a mass of 0.62 g.

[0061] 5. Add 25 mg of the hydroxy intermediate to 10 mL of N,N-dimethylformamide and stir until the hydroxy intermediate is completely dispersed to obtain a dispersion. Add 0.5 mmol of 2,4-dinitrofluorobenzene to the dispersion under nitrogen protection in an ice bath, and then add triethylamine to adjust the pH of the dispersion to 9. Stir at room temperature for 6 h.

[0062] 6. After the reaction is completed, the filter cake is filtered and washed three times with a mixed solvent II of tetrahydrofuran and ethanol in a volume ratio of 1:1. After vacuum drying, a fluorescent covalent organic framework material for H2S detection is obtained, with a mass of 19.4 mg.

[0063] The structure of the fluorescent covalent organic framework material for H2S detection prepared in Example 1 was characterized by Fourier transform infrared spectroscopy. The infrared spectrum obtained is as follows: Figure 1 As shown. Figure 1 It can be seen that at 1665 cm -1 and 1550 cm -1 The characteristic absorption peaks of C=N and NO appeared at , indicating that the two covalent organic framework materials were successfully prepared.

[0064] The structure of the fluorescent covalent organic framework material for H2S detection prepared in Example 1 was characterized by N 1s high-resolution energy spectrum. The energy spectrum obtained is shown in FIG. Figure 2 As shown. Figure 2 It can be seen that a new peak at 404.88 e is attributed to the ONO bond, proving that the nitro group was successfully modified.

[0065] From the above characterization results, it can be seen that the periodic structural fragments of the fluorescent covalent organic framework material for H2S detection prepared in this example are:

[0066]

[0067] The spectral performance of the fluorescent covalent organic framework material for H2S detection prepared in Example 1 was tested as follows:

[0068] 1. Solution preparation:

[0069] The concentration of the fluorescent covalent organic framework material used for H2S detection was 0.1 g·L-1 , the fluorescent covalent organic framework material for H2S detection is uniformly dispersed in N,N-dimethylformamide solution to obtain probe solution A;

[0070] Weigh 4 mg of sodium hydrosulfide as the H2S source and add it to a 10 mL volumetric flask. -1 A mixture of PBS buffer solution (pH = 7.4) and N, N-dimethylformamide (volume ratio: 3:7) was made up to volume, and ultrasonic vibration was performed to completely dissolve the sodium hydrosulfide to obtain a concentration of 0.005 mol·L -1 H2S stock solution;

[0071] Weigh different amounts of amino acids (glutathione, histidine, alanine, arginine, aspartic acid, glutamic acid, cysteine, glycine, leucine, methionine, phenylalanine, proline, serine, tryptophan, tyrosine, and valine) and anionic sodium salts (sodium iodide, sodium bromide, sodium chloride, sodium fluoride, sodium bisulfate, sodium sulfate, sodium sulfite, sodium bicarbonate, sodium carbonate, sodium nitrate, sodium nitrite, sodium hydrogen phosphate, sodium thiocyanide, and sodium acetate) and add them to a 10 mL volumetric flask. -1 , pH = 7.4 water buffer solution to the fixed volume, ultrasonic vibration uniform, so that different types of amino acids and anions are completely dissolved, to obtain a concentration of 0.005 mol·L -1 Stock solutions of different types of amino acids and anions;

[0072] 2. Spectral performance test:

[0073] 0.1 g·L -1 0.005 mol·L -1 Different types of amino acid and anion stock solutions were prepared and ultrasonically shaken for 5 min to obtain a mixed solution;

[0074] With 320 nm as the excitation wavelength, 0.1 g·L -1 Probe solution A, add 0.005 mol·L -1 The fluorescence emission spectra of mixed solutions of different types of amino acids and anion stock solutions and mixed solutions with H2S stock solution added are as follows. Figure 3 and Figure 4 As shown. Figure 3 It can be seen that the fluorescence emission wavelength of the probe solution A prepared in this embodiment is 424 nm and the fluorescence intensity is 98 au. Figure 4It can be seen from the figure that after adding different types of amino acids and anion stock solutions, the fluorescence intensity of probe solution A did not change much, ranging from 75 au to 150 au. -1 After adding the H2S stock solution, the emission wavelength shifted significantly to 466 nm, red-shifting by 42 nm. Furthermore, the fluorescence intensity increased significantly to 281 au, a three-fold increase. Therefore, the fluorescence emission spectrum indicates that the fluorescent covalent organic framework prepared in this example has selective recognition properties for H2S.

[0075] The ability of the probe solution A of Example 1 to resist interference from different types of amino acids and anions in H2S detection was tested. The specific testing method was as follows: -1 0.005 mol·L was added to the probe solution A. -1 Different types of amino acids and anion stock solutions were mixed, and then 0.005 mol·L -1 The H2S stock solution was prepared into a mixed test solution of probe, identification substance and interference substance. After thorough shaking, ultrasonic vibration was performed for 5 minutes, and fluorescence test was performed. The results were as follows: Figure 5 As shown. Figure 5 It can be seen that in the presence of different types of amino acids and anions, when H2S coexists with different types of amino acids and anions, the fluorescence intensity of probe solution A hardly changes. Therefore, it can be inferred from the fluorescence spectrum that the fluorescent covalent organic framework material prepared in this example is not interfered with by different types of amino acids and anions in the fluorescence detection of H2S.

[0076] The response ability of the probe solution A of Example 1 to H2S at different pH values ​​was tested. The specific test method was as follows: the pH value was 2-13 and the concentration was 0.1 g·L -1 0.005 mol·L was added to the probe solution A. -1 After thorough shaking, ultrasonic vibration for 5 minutes, and fluorescence test, the results are as follows Figure 6 As shown. Figure 6 It can be seen that under different pH conditions, the fluorescence of the probe hardly changes, and the fluorescence does not change significantly after the addition of H2S. Therefore, it can be inferred that the fluorescence detection of H2S by the fluorescent covalent organic framework material prepared in this example is not interfered by the acidic and alkaline environment.

[0077] The response ability of the probe solution A of Example 1 to different H2S concentrations was tested. The specific test method was as follows: -1 Add 0~0.005 mol·L -1After being thoroughly shaken and ultrasonically shaken for 5 minutes, fluorescence test was performed. The results were as follows: Figure 7 As shown. Figure 7 It can be seen that with the increase of H2S concentration, the fluorescence intensities at emission wavelengths of 424 nm and 466 nm both increase, and the fluorescence intensity enhancement rate at 466 nm is greater than that at 424 nm, showing a phenomenon of gradual red shift of the fluorescence emission wavelength. Figure 8 The linear fitting diagram of the fluorescence emission spectrum of Example 1 shows that the fluorescence emission intensity is linearly correlated with the H2S concentration, and the linear equation is y=0.718[H2S]+9.318, R 2 =0.995, and the linear range is 0~100μM.

[0078] Example 2: The preparation method of the fluorescent covalent organic framework material for H2S detection in this example is carried out according to the following steps:

[0079] 1. To a mixed solvent I of 1.6 mL of mesitylene and 0.4 mL of dioxane, 0.06 mol of phenanthroimidazole-hydroxy monomer and 0.04 mol of triazine aldehyde monomer were added, respectively, and 0.003 mol of trifluoroacetic acid was added as a catalyst, and the mixture was mixed to obtain a reaction solution I.

[0080] 2. Add reaction solution I into the Schlenk tube, and then perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen environment in the Schlenk tube;

[0081] 3. Maintain the temperature of the Schlenk tube at 140°C and react for 3 days;

[0082] 4. After the reaction, cool to room temperature, filter, and wash the filter cake repeatedly with a mixed solvent II of acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a hydroxy intermediate with a mass of 0.60 g was obtained;

[0083] 5. To 10 mL of anhydrous DMF, add 20 mg of the hydroxy intermediate and stir until the hydroxy intermediate is completely dispersed to obtain a dispersion; add 0.2 mmol of 2,4-dinitrofluorobenzene to the dispersion under nitrogen protection in an ice bath, then add sodium carbonate to adjust the pH value of the dispersion to 9, and stir at room temperature for 8 h;

[0084] 6. After the reaction is completed, the filter cake is filtered and washed repeatedly three times with a mixed solvent II of acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a fluorescent covalent organic framework material for H2S detection is obtained, with a mass of 18.2 mg.

[0085] Example 3: The preparation method of the fluorescent covalent organic framework material for H2S detection in this example is carried out according to the following steps:

[0086] 1. To a mixed solvent I of 1.4 mL of xylene and 0.6 mL of N, N-dimethylformamide, 0.08 mol of phenanthroimidazole-hydroxy monomer and 0.04 mol of triazine aldehyde monomer were added, respectively, and 0.008 mol of benzenesulfonic acid as a catalyst was added, and the mixture was mixed to obtain a reaction solution I.

[0087] 2. Add reaction solution I into the Schlenk tube, and then perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen environment in the Schlenk tube;

[0088] 3. Maintain the temperature of the Schlenk tube at 140°C and react for 4 days;

[0089] 4. After the reaction, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II of tetrahydrofuran and dichloromethane in a volume ratio of 1:1. After vacuum drying, a hydroxy intermediate was obtained with a mass of 0.59 g.

[0090] 5. To 10 mL of anhydrous DMF, add 30 mg of the hydroxy intermediate and stir until the hydroxy intermediate is completely dispersed to obtain a dispersion. Add 0.4 mmol of 2,4-dinitrofluorobenzene to the dispersion under nitrogen protection in an ice bath, and then add potassium carbonate to adjust the pH of the dispersion to 9. Stir at room temperature for 10 h.

[0091] 6. After the reaction, the filter cake was filtered and washed three times with a mixed solvent II of methanol and ethanol in a volume ratio of 1:1. After vacuum drying, a fluorescent covalent organic framework material for H2S detection was obtained, with a mass of 19.0 mg.

[0092] Example 4: The preparation method of the fluorescent covalent organic framework material for H2S detection in this example is carried out according to the following steps:

[0093] 1. To a mixed solvent I of 1.2 mL of o-dichlorobenzene and 0.8 mL of n-butanol, 0.1 mol of phenanthroimidazole-hydroxy monomer and 0.04 mol of triazine aldehyde monomer were added, respectively, and 0.005 mol of benzoic acid as a catalyst was added, and the mixture was mixed uniformly to obtain a reaction solution I;

[0094] 2. Add reaction solution I into the Schlenk tube, and then perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen environment in the Schlenk tube;

[0095] 3. Maintain the temperature of the Schlenk tube at 160°C and react for 5 days;

[0096] 4. After the reaction, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II of methanol and dichloromethane in a volume ratio of 1:1. After vacuum drying, a hydroxy intermediate was obtained with a mass of 0.64 g.

[0097] 5. To 10 mL of anhydrous DMF, add 35 mg of the hydroxy intermediate and stir until the hydroxy intermediate is completely dispersed to obtain a dispersion; add 0.3 mmol of 2,4-dinitrofluorobenzene to the dispersion under nitrogen protection in an ice bath, and then add calcium hydroxide to adjust the pH value of the dispersion to 9, and stir at room temperature for 12 h;

[0098] 6. After the reaction is completed, the filter cake is filtered and washed three times with a mixed solvent II of acetone and ethyl acetate in a volume ratio of 1:1. After vacuum drying, a fluorescent covalent organic framework material for H2S detection is obtained, with a mass of 19.6 mg.

[0099] Example 5: The preparation method of the fluorescent covalent organic framework material for H2S detection in this example is carried out according to the following steps:

[0100] 1. To a mixed solvent I of 1.0 mL of mesitylene and 1.0 mL of dioxane, 0.12 mol of phenanthroimidazole-hydroxy monomer and 0.04 mol of triazine aldehyde monomer were added, respectively, and 0.012 mol of p-toluenesulfonic acid was added as a catalyst, and the mixture was mixed to obtain a reaction solution I.

[0101] 2. Add reaction solution I into the Schlenk tube, and then perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen environment in the Schlenk tube;

[0102] 3. Maintain the temperature of the Schlenk tube at 180°C and react for 6 days;

[0103] 4. After the reaction, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II of acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a hydroxy intermediate was obtained with a mass of 0.56 g.

[0104] 5. To 10 mL of anhydrous DMF, add 40 mg of the hydroxy intermediate and stir until the hydroxy intermediate is completely dispersed to obtain a dispersion. Add 0.6 mmol of 2,4-dinitrofluorobenzene to the dispersion under nitrogen protection in an ice bath, then add pyridine to adjust the pH of the dispersion to 9, and stir at room temperature for 14 h.

[0105] 6. After the reaction is completed, the filter cake is filtered and washed three times with a mixed solvent II of tetrahydrofuran and ethanol in a volume ratio of 1:1. After vacuum drying, a fluorescent covalent organic framework material for H2S detection is obtained, with a mass of 19.2 mg.

[0106] Example 6: The preparation method of the fluorescent covalent organic framework material for H2S detection in this example is carried out according to the following steps:

[0107] 1. To a mixed solvent I of 1.2 mL of n-butanol and 0.8 mL of o-dichlorobenzene, 0.12 mol of phenanthroimidazole-hydroxy monomer and 0.04 mol of triazine aldehyde monomer were added, respectively, and 0.006 mol of glacial acetic acid was added as a catalyst, and the mixture was mixed uniformly to obtain a reaction solution I;

[0108] 2. Add reaction solution I into the Schlenk tube, and then perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen environment in the Schlenk tube;

[0109] 3. Maintain the temperature of the Schlenk tube at 200°C and react for 7 days;

[0110] 4. After the reaction, the mixture was cooled to room temperature and filtered. The filter cake was repeatedly washed with a mixed solvent II of acetone and dichloromethane in a volume ratio of 1:1. After vacuum drying, a hydroxy intermediate with a mass of 0.65 g was obtained.

[0111] 5. To 10 mL of anhydrous DMF, add 35 mg of the hydroxy intermediate and stir until the COF is completely dispersed. Then, add 0.7 mmol of 2,4-dinitrofluorobenzene under nitrogen protection and calcium carbonate to adjust the pH of the dispersion to 9. Stir at room temperature for 16 h.

[0112] 6. After the reaction is completed, the filter cake is filtered and repeatedly washed with a mixed solvent II of acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a fluorescent covalent organic framework material for H2S detection is obtained, with a mass of 18.8 mg;

[0113] Example 7: The preparation method of the fluorescent covalent organic framework material for H2S detection in this example is carried out according to the following steps:

[0114] 1. To a mixed solvent I of 1.4 mL of mesitylene and 0.6 mL of dioxane, 0.14 mol of phenanthroimidazole-hydroxy monomer and 0.04 mol of triazine aldehyde monomer were added, respectively, and 0.014 mol of benzenesulfonic acid as a catalyst was added, and the mixture was mixed uniformly to obtain a reaction solution I;

[0115] 2. Add reaction solution I into the Schlenk tube, and then perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen environment in the Schlenk tube;

[0116] 3. Maintain the temperature of the Schlenk tube at 150°C and react for 4 days;

[0117] 4. After the reaction, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II of tetrahydrofuran and ethanol in a volume ratio of 1:1. After vacuum drying, a hydroxy intermediate was obtained with a mass of 0.59 g.

[0118] 5. To 10 mL of anhydrous DMF, add 35 mg of the hydroxy intermediate and stir until the hydroxy intermediate is completely dispersed. Add 0.8 mmol of 2,4-dinitrofluorobenzene under nitrogen protection, and then add pyridine to adjust the pH value of the dispersion to 9. Stir at room temperature for 18 hours.

[0119] 6. After the reaction is completed, the filter cake is filtered and washed three times with a mixed solvent II of tetrahydrofuran and ethyl acetate in a volume ratio of 1:1. After vacuum drying, a fluorescent covalent organic framework material for H2S detection is obtained, with a mass of 19.4 mg.

[0120] Example 8: The preparation method of the fluorescent covalent organic framework material for H2S detection in this example is carried out according to the following steps:

[0121] 1. To a mixed solvent I of 1.5 mL of xylene and 0.5 mL of N, N-dimethylformamide, 0.16 mol of phenanthroimidazole-hydroxy monomer and 0.04 mol of triazine aldehyde monomer were added, respectively, and 0.016 mol of benzoic acid as a catalyst was added, and the mixture was mixed to obtain a reaction solution I.

[0122] 2. Add reaction solution I into the Schlenk tube, and then perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen environment in the Schlenk tube;

[0123] 3. Maintain the temperature of the Schlenk tube at 170°C and react for 5 days;

[0124] 4. After the reaction, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II of acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a hydroxy intermediate was obtained with a mass of 0.69 g.

[0125] 5. To 10 mL of anhydrous DMF, add 25 mg of the hydroxy intermediate and stir until the hydroxy intermediate is completely dispersed. Add 0.8 mmol of 2,4-dinitrofluorobenzene under nitrogen protection, and then add sodium carbonate to adjust the pH value of the dispersion to 9. Stir at room temperature for 18 hours.

[0126] 6. After the reaction is completed, the filter cake is filtered and washed three times with a mixed solvent II of acetone and ethanol in a volume ratio of 1:1. After vacuum drying, a fluorescent covalent organic framework material for H2S detection is obtained, with a mass of 18.9 mg.

[0127] Example 9: The preparation method of the fluorescent covalent organic framework material for H2S detection in this example is carried out according to the following steps:

[0128] 1. To a mixed solvent I of 1.6 mL of mesitylene and 0.4 mL of dioxane, 0.2 mol of phenanthroimidazole-hydroxy monomer and 0.04 mol of triazine aldehyde monomer were added, respectively, and 0.02 mol of glacial acetic acid was added as a catalyst, and the mixture was mixed to obtain a reaction solution I.

[0129] 2. Add reaction solution I into the Schlenk tube, and then perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen environment in the Schlenk tube;

[0130] 3. Maintain the temperature of the Schlenk tube at 130°C and react for 3 days;

[0131] 4. After the reaction, the mixture was cooled to room temperature and filtered. The filter cake was washed three times with a mixed solvent II of acetone and dichloromethane in a volume ratio of 1:1. After vacuum drying, a hydroxy intermediate was obtained with a mass of 0.67 g.

[0132] 5. To 10 mL of anhydrous DMF, add 35 mg of the hydroxy intermediate and stir until the COF is completely dispersed. Then, add 1.0 mmol of 2,4-dinitrofluorobenzene under nitrogen protection, and then add potassium carbonate to adjust the pH of the dispersion to 9. Stir at room temperature for 24 h.

[0133] 6. After the reaction is completed, the filter cake is filtered and washed three times with a mixed solvent II of tetrahydrofuran and ethanol in a volume ratio of 1:1. After vacuum drying, a fluorescent covalent organic framework material for H2S detection is obtained, with a mass of 19.5 mg.

Claims

1. A fluorescent covalent organic framework material for hydrogen sulfide detection, characterized in that: The periodic structural fragments of this material are: 。 2. A method for preparing a fluorescent covalent organic framework material for hydrogen sulfide detection, characterized in that: The method proceeds as follows:

1. adding a phenanthroimidazole-hydroxy monomer and a triazine aldehyde monomer to a mixed solvent I at a molar ratio of 1 to 5:1, then adding an acid as a catalyst to the mixed solvent I at a molar ratio of 1 to 0.01 to 0.1, and mixing uniformly to obtain a reaction solution I; wherein the phenanthroimidazole-hydroxy monomer is 3-(5,10-diamino-1H-phenanthrene)[9,10-d]imidazol-2-yl)phenol, and the triazine aldehyde monomer is 2,4,6-tris(4-formylphenoxy)-1,3,5-triazine; 2. Add reaction solution I into the Schlenk tube, and perform a cycle of vacuuming and nitrogen filling on the Schlenk tube to maintain a nitrogen atmosphere in the Schlenk tube; 3. Raise the temperature of the Schlenk tube to 100-200°C and maintain for 1-7 days to carry out the reaction; 4. After the reaction is completed, the temperature is lowered to room temperature, filtered, and the filter cake is washed with mixed solvent II and vacuum dried to obtain a hydroxy intermediate; 5. Add the hydroxy intermediate and 2,4-dinitrofluorobenzene to an organic solvent at a ratio of (20-400) mg to 1 mmol, then add a base to provide an alkaline environment and promote the reaction, and react at room temperature for 6-24 hours.

6. After the reaction is completed, the filter cake is filtered and washed with mixed solvent II. After vacuum drying, a fluorescent covalent organic framework material for hydrogen sulfide detection is obtained.

3. The method for preparing a fluorescent covalent organic framework material for hydrogen sulfide detection according to claim 2, characterized in that: The mixed solvent I described in step 1 is any two of xylene, mesitylene, o-dichlorobenzene, N,N-dimethylformamide, dioxane and n-butanol.

4. The method for preparing a fluorescent covalent organic framework material for hydrogen sulfide detection according to claim 2 or 3, characterized in that: The acid described in step 1 is glacial 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%.

5. The method for preparing a fluorescent covalent organic framework material for hydrogen sulfide detection according to claim 2 or 3, characterized in that: The molar ratio of the acid and the phenanthroimidazole-hydroxy monomer in step 1 is (0.05-0.12):

1.

6. The method for preparing a fluorescent covalent organic framework material for hydrogen sulfide detection according to claim 2 or 3, characterized in that: The mixed solvent II described in step 4 and step 6 is any two of tetrahydrofuran, methanol, ethanol, ethyl acetate, acetone, dichloromethane, chloroform or 1,2-dichloroethane.

7. The method for preparing a fluorescent covalent organic framework material for hydrogen sulfide detection according to claim 2 or 3, characterized in that: The organic solvent described in step 5 is dichloromethane, tetrahydrofuran, acetone, methanol, ethanol or N, N-dimethylformamide.

8. The method for preparing a fluorescent covalent organic framework material for hydrogen sulfide detection according to claim 2 or 3, characterized in that: The alkaline environment described in step 5 refers to a pH value of 8 to 12.

9. Application of fluorescent covalent organic framework materials for hydrogen sulfide detection, characterized in that: This application is to use the fluorescent covalent organic framework material used for hydrogen sulfide detection as a fluorescent material for the detection of H2S.

10. The use of the fluorescent covalent organic framework material for hydrogen sulfide detection according to claim 9, characterized in that: The method for qualitative detection of H2S using a fluorescent covalent organic framework material for H2S detection is carried out in the following steps: First, the fluorescent covalent organic framework material for hydrogen sulfide detection was uniformly dispersed in a mixture of PBS buffer solution (pH = 7.4) and N, N-dimethylformamide (volume ratio: 3:(1-7)) to obtain probe solution A. The concentration of the fluorescent covalent organic framework material for H2S detection in probe solution A was 0.01-0.1 g·L -1 ; 2. Add the sample I to the probe solution A and mix evenly to obtain the test solution B; 3. Measure the fluorescence emission spectrum of probe solution A with an excitation wavelength of 320 nm and record the emission intensity at an emission wavelength of 424 nm, which is recorded as T A ; 4. Measure the fluorescence emission spectrum of solution B with an excitation wavelength of 320 nm and record the emission intensity at a wavelength of 466 nm, which is recorded as T B ; 5. Comparison T A and T B , if T A >T B , it is determined that the sample to be tested contains H2S.

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