A furanyl oxadiazolone compound, a preparation method thereof and application thereof in detecting CO3 2- or PO4 3- ​

Abstract

The application discloses a furan oxadiazole ketone compound and a preparation method and application thereof in detecting CO3 2‑ or PO4 3‑ . The furan oxadiazole ketone compound has a structural formula. The application further provides a preparation method of the furan oxadiazole ketone compound, which comprises the following steps: reacting 5-nitrofuran-2-carboxylic acid and oxalyl chloride to obtain 5-nitrofuran-2-carbonyl chloride, then acylating 2-hydrazinyl pyrimidine with 5-nitrofuran-2-carbonyl chloride to obtain 5-nitro-N'-(2-pyrimidinyl) furan-2-carbonyl hydrazine, and forming a ring of the 5-nitro-N'-(2-pyrimidinyl) furan-2-carbonyl hydrazine with triphosgene to obtain the furan oxadiazole ketone compound. The furan oxadiazole ketone compound provided by the application is an optical probe, which can be used as a fluorescent probe to detect CO3 2‑ or PO4 3‑ in environmental water bodies, and has strong anti-interference ability.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, specifically to a furanyloxadiazolone compound, its preparation method, and its application in the detection of CO3. 2- Or PO4 3- Applications in [the field]. Background Technology

[0002] carbonates (CO3) 2- ) and phosphate (PO4) 3- Carbonates and phosphates are two common chemical substances with extremely wide applications, covering almost all important areas of modern society. For example, carbonates are widely used in construction, agriculture, food and pharmaceuticals, and polymer processing, while phosphates, as another crucial class of inorganic compounds, are used in fine chemicals, electronics and new energy, chemical production, and even high-tech fields. However, excessive or improper use of carbonates and phosphates can also pose threats to ecosystems and human health. When excessive carbonate and phosphate anions are released into water, it can lead to water acidification and eutrophication, affecting the survival and reproduction of aquatic organisms. Humans absorb low concentrations of PO4 through drinking water. 3 - Ions can lead to a range of health problems, such as muscle weakness, heart failure, seizures, or coma. Given CO3... 2- and PO4 3- Given their profound impact on ecosystems and human life, tracking and quantifying these two anions is essential for preventing and eliminating environmental pollution, especially water pollution.

[0003] There are various analytical methods for detecting carbonate and phosphate ions, mainly including chemical titration, electrochemical methods, spectrophotometry, and chromatography. However, these methods typically suffer from drawbacks such as long processing times, high costs, and the need for skilled operators. These shortcomings, however, leave ample room for the development of selective, sensitive, and quantitative fluorescent chemical sensors, due to the advantages of high sensitivity, simplicity, low cost, rapid response, and real-time monitoring inherent in fluorescent molecular sensing methods. Currently, research on fluorescence-based anion sensors is relatively extensive. However, reports on sensors that can be used for both carbonate and phosphate anion fluorescence detection are scarce. Therefore, the development of a sensor capable of detecting both CO32- and CO22- is a priority. 2- It can also be used to detect PO4. 3- The dual fluorescent probe can expand the application range of fluorescence detection. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for detecting CO3. 2- Or PO4 3- A dual fluorescent probe.

[0005] The present invention solves the above-mentioned technical problems through the following technical means:

[0006] A furanyloxadiazolone compound, the structural formula of which is shown below: .

[0007] Beneficial effects: The compound obtained by this invention has a large conjugated structure and can emit fluorescence under ultraviolet light excitation, making it a method for detecting low concentrations of CO3 using fluorescence emission spectroscopy. 2- Or PO4 3- Dual optical probes.

[0008] This invention also provides a method for preparing the aforementioned furanyloxadiazolone compound, comprising the following steps: S1. 5-Nitrofuran-2-carboxylic acid and oxaloyl chloride are reacted to obtain 5-nitrofuran-2-carboxylic chloride; S2. Acylation of 2-hydrazinopyrimidine with 5-nitrofuran-2-carboxyl chloride yields 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazide; S3. The furanyloxadiazolone compound is obtained by cyclizing 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine with triphosgene.

[0009] Preferably, in S1, the reaction temperature is room temperature, and in S2 and S3, the reaction temperature is controlled within the range of -5 to 10°C; the reaction solvent used is one or more of dichloromethane, trichloromethane and carbon tetrachloride; and the reaction time is 2-4 hours.

[0010] Beneficial effects: Some of the raw materials involved in the method for preparing the compounds in this invention are easily decomposed by protic solvents, so non-protic organic compounds must be used as solvents.

[0011] Preferably, in S1, the molar ratio of 5-nitrofuran-2-carboxylic acid to oxaloyl chloride is 1:1.2~1.5; in S2, the molar ratio of 2-hydrazinopyrimidine to 5-nitrofuran-2-carboxyl chloride is 1:1.2~2; and in S3, the molar ratio of 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine to triphosgene is 1:1.2~1.5.

[0012] Preferably, in S2 and S3, triethylamine is added for reaction; the molar ratio of 2-hydrazinopyrimidine, triethylamine and 5-nitrofuran-2-carboxyl chloride in S2 is 1:1.5~3:1.2~2; the molar ratio of 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine, triethylamine and triphosgene in S3 is 1:1~3:1.2~1.5.

[0013] Beneficial effect: In S1, the oxalyl chloride involved in the synthesis is easily decomposed, so an excess is used to improve the product yield.

[0014] Beneficial effect: In S2, the 5-nitrofuran-2-formyl chloride involved in the synthesis is easily decomposed, so an excess is used to improve the product yield.

[0015] Beneficial effect: In S3, the triphosgene involved in the synthesis is easily decomposed, so an excess of it is used to improve the product yield.

[0016] Preferably, steps S2 and S3 further include washing the reaction product with double-distilled water.

[0017] Beneficial effect: The product is purified by washing the product with double-distilled water to remove triethylamine.

[0018] Preferably, in S1, the specific process of reacting 5-nitrofuran-2-carboxylic acid with oxalyl chloride to obtain 5-nitrofuran-2-carboxylic chloride includes the following steps: dissolving 5-nitrofuran-2-carboxylic acid in a solvent, adding a solution containing oxalyl chloride dropwise at room temperature, and continuing the reaction for 1-2 hours after the addition is complete; ending the reaction, recovering the solvent by vacuum distillation, washing, and drying to obtain the 5-nitrofuran-2-carboxylic chloride.

[0019] Preferably, in S2, 2-hydrazinopyrimidine and triethylamine are dissolved in a solvent, and under nitrogen protection, a solution containing 5-nitrofuran-2-carboxyl chloride is added dropwise at -5~10°C. After the addition is complete, the mixture is stirred at -5~10°C for 2~4 hours. After the reaction is completed, the mixture is filtered, washed, and dried to obtain the 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine.

[0020] Preferably, in S3, the specific process of cyclizing 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine with triphosgene to obtain the oxadiazolone compound includes the following steps: dissolving 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine and triethylamine in a solvent, adding a solution containing triphosgene dropwise under nitrogen protection at -5~10°C, and stirring the reaction at -5~10°C for 2~4 hours after the addition is complete; after the reaction is completed, filtering, washing, and drying are performed to obtain the furanyloxadiazolone compound.

[0021] Preferably, the method for preparing the furanyloxadiazolone compound includes the following steps: Preparation of S1, 5-nitrofuran-2-carboxylic acid: The molar ratio of 5-nitrofuran-2-carboxylic acid to oxaloyl chloride is 1:1.2~1.5. First, 5-nitrofuran-2-carboxylic acid is dissolved in a solvent. Then, the solution obtained by dissolving oxaloyl chloride in the same solvent is added dropwise at room temperature. After the addition is complete, the reaction is continued to be stirred at room temperature for 1~2 hours. After the reaction is complete, the solvent is removed by vacuum distillation. The solid is washed with diethyl ether to obtain solid 5-nitrofuran-2-carboxylic acid. Preparation of S2, 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine: Based on a molar ratio of 2-hydrazinopyrimidine, triethylamine, and 5-nitrofuran-2-carboxyl chloride of 1:1.5~3:1.2~2, 2-hydrazinopyrimidine and triethylamine were first dissolved in a solvent. Under nitrogen protection, the solution obtained by dissolving 5-nitrofuran-2-carboxyl chloride in the above solvent was added dropwise at -5~10℃. After the addition was complete, the mixture was stirred at -5~10℃ for 2~4 hours. After the reaction was completed, the mixture was filtered, the filter cake was washed with double-distilled water, and dried to obtain solid 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine. Preparation of S3, 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one: Based on a molar ratio of 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine, triethylamine, and triphosgene of 1:1~3:1.2~1.5, 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine and triethylamine were first dissolved in a solvent and kept under nitrogen atmosphere. Under the protection of the solvent, a solution obtained by dissolving triphosgene in the above solvent was added dropwise at -5~10℃. After the addition was completed, the mixture was stirred at -5~10℃ for 2~4 hours. After the reaction was completed, the mixture was filtered, and the filter cake was washed with double-distilled water and dried to obtain the solid product 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one, which is the furanyloxadiazolone compound.

[0022] Beneficial Effects: This invention prepares the above-mentioned furanyloxadiazolone compound via a three-step method, with the reaction temperature at each stage directly affecting the product yield. Experiments show that when the reaction temperature is below -5℃, the yield of 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine is below 17%, and the yield of 5-(2-(5-nitrofuran)yl)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one is below 11%; when the reaction temperature is above 10℃, the product yield at each stage is below 27%.

[0023] This invention also proposes a method for detecting CO3 in water using the aforementioned furanyloxadiazolone compound. 2- Or PO4 3- Applications in [the field].

[0024] Preferably, the furanyloxadiazolone compound is used as a fluorescent probe.

[0025] Beneficial effects: This furanyloxadiazolone compound can be used as a fluorescent probe to detect trace amounts of CO3 in actual water bodies. 2- Or PO4 3- It has practicality, convenience and accuracy in detection.

[0026] Preferably, the furanyloxadiazolone compound is used as a fluorescent probe to detect CO3. 2- The concentration range is 7.5 × 10⁻⁶. -5 ~2.0×10 -4 mol L -1 .

[0027] Preferably, the furanyloxadiazolone compound is used as a fluorescent probe to detect PO4. 3- The concentration range is 6.0 × 10⁻⁶. -5 ~1.0×10 -4 mol L -1 .

[0028] Preferably, the CO3 2- Or PO4 3- CO3 in the aquatic environment 2- Or PO4 3- .

[0029] Preferably, CO3 is detected. 2- At that time, the linear equation is I0 / I = 0.132 + 1.529 × 10 4 C; Detection of PO4 3- At that time, the linear equation is I0 / I = -0.868 + 3.892 × 10 4 C; where C is CO3 2- Or PO4 3- The concentration, in mol L -1 I0 and I are CO3 2- Or PO4 3- Fluorescence intensity at concentrations of 0 and C.

[0030] Preferably, during the detection process, the prepared furanyloxadiazolone compound is added to an ethanol solvent to prepare a solution before use.

[0031] Preferably, during the detection process, the prepared furanyloxadiazolone compound is added to an ethanol solvent to prepare a solution, which is then injected into a cuvette to measure its fluorescence emission spectrum. CO3 is then added to the cuvette sequentially. 2- Aqueous solution, determination of different CO3 2- Fluorescence emission spectra of solutions at various concentrations.

[0032] Beneficial effects: The measured relative fluorescence intensity (I0 / I) (I0 and I are CO32- and CO32- respectively) 2- Fluorescence intensity at concentrations of 0 and C, where C is in mol / L. -1 ) and CO3 2- The relationship between concentration (C) and CO3 concentration shows that as CO3 increases... 2- With increasing concentration, the emission wavelength λ em =425nm (excitation wavelength λ) ex The fluorescence emission intensity at 371 nm (=371 nm) decreases rapidly, and at 7.5 × 10⁻⁶ nm... -5 ~ 2.0×10 -4 mol L -1 Relative fluorescence intensity within the range and CO3 2- The concentration exhibits a good linear relationship, with the linear equation being I0 / I = 0.132 + 1.529 × 10⁻⁶. 4 C, in the equation, is CO3. 2- Concentration. This allows for the detection of low concentrations of CO3. 2- .

[0033] Preferably, during the detection process, the prepared furanyloxadiazolone compound is added to an ethanol solvent to prepare a solution, which is then injected into a cuvette, and CO3 is removed separately. 2- and PO4 3- For aqueous solutions containing other anions, test the fluorescence emission spectrum of the solution containing that ion, and then add CO3. 2- Aqueous solution containing CO3 2- CO3 in aqueous solution 2- The molar amount of the mixed anions was the same as that of the other anions added, and the fluorescence emission spectrum of the solution containing the mixed anions was tested again.

[0034] Beneficial Effects: In practical applications, fluorescent probes are often used to detect water samples containing multiple anions, not just a single type. Therefore, interference resistance is a crucial indicator for probe evaluation. Test results show that the prepared compound probe exhibits excellent resistance to anion interference, making it a highly practical method for CO3 detection. 2- Fluorescent probes.

[0035] Preferably, during the detection process, the prepared furanyloxadiazolone compound is added to an ethanol solvent to prepare a solution, which is then injected into a cuvette to measure its fluorescence emission spectrum. PO4 is then added to the cuvette sequentially. 3- Aqueous solution, determination of different PO4 3- Fluorescence emission spectra of solutions at various concentrations.

[0036] Beneficial effects: The measured relative fluorescence intensity (I0 / I) (I0 and I are respectively PO42-) 3- Fluorescence intensity at concentrations of 0 and C, where C is in mol / L. -1 ) and PO4 3- The relationship between concentration (C) and PO4 concentration indicates that as PO4 increases... 3- With increasing concentration, the emission wavelength λ em =425nm (excitation wavelength λ) ex The fluorescence emission intensity at 371 nm (=371 nm) decreases rapidly, and at 6.0 × 10⁻⁶ nm... -5 ~1.0×10 -4 mol L -1 Relative fluorescence intensity within the range and PO4 3- The concentration exhibits a good linear relationship, with the linear equation being I0 / I = -0.868 + 3.892 × 10⁻⁶. 4 C, in the equation, C is PO4. 3- Concentration. This allows for the detection of low concentrations of PO4. 3- .

[0037] Preferably, during the detection process, the prepared furanyloxadiazolone compound is added to an ethanol solvent to prepare a solution, which is then injected into a cuvette, and CO3 is removed separately. 2- and PO4 3- For aqueous solutions containing other anions, test the fluorescence emission spectrum of the solution containing that ion, and continue adding PO4. 3- Aqueous solution containing PO4 3- PO4 in aqueous solution 3- The molar amount of the mixed anion was the same as the molar amount of the added anion, and the fluorescence emission spectrum of the solution containing the mixed anion was tested again.

[0038] Beneficial Effects: In practical applications, fluorescent probes are often used to detect water samples containing multiple anions, not just a single type. Therefore, interference resistance is a crucial indicator for probe evaluation. Test results show that the prepared compound probe exhibits excellent resistance to anion interference, making it a highly practical method for detecting PO4. 3- Fluorescent probes.

[0039] Preferably, the CO3 removal 2- and PO4 3- Other anionic aqueous solutions are MnO4 - Aqueous solution, ClO4 - Aqueous solution, NO3 - Aqueous solution, SO4 2- Aqueous solution, [Fe(CN)6] 3- Aqueous solution, HCO3 - Aqueous solution, Br- Aqueous solution, SCN - Aqueous solution, F - Aqueous solution, Cr2O7 2- Aqueous solution, I - Aqueous solution, Cl - Aqueous solution and CrO4 2- One or more of the following in aqueous solution.

[0040] Preferably, the CO3 removal 2- and PO4 3- Other anionic aqueous solutions include one or more of the following: potassium permanganate aqueous solution, potassium perchlorate aqueous solution, potassium nitrate aqueous solution, potassium sulfate aqueous solution, potassium thiocyanate aqueous solution, potassium bicarbonate aqueous solution, potassium bromide aqueous solution, potassium fluoride aqueous solution, potassium chloride aqueous solution, potassium iodide aqueous solution, potassium dichromate aqueous solution, potassium chromate aqueous solution, and potassium hexacyanoferrate aqueous solution.

[0041] Preferably, the CO3 2- The aqueous solution is a potassium carbonate solution.

[0042] Preferably, the PO4 3- The aqueous solution is a potassium phosphate solution.

[0043] The advantages of this invention are: the synthetic method of the furanyloxadiazolone compound 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one is simple and the reaction conditions are mild. This compound can be used as a fluorescent probe to detect low concentrations of CO3 in water. 2- It can also be used as a fluorescent probe to detect low concentrations of PO4 in water. 3- It also has good anti-interference capabilities. Attached Figure Description

[0044] Figure 1 The normal mass spectrum of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one prepared in Example 1 of this invention; Figure 2 The solid infrared spectrum (KBr tablet) of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one prepared in Example 1 of this invention. Figure 3 The 1H NMR spectrum of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one prepared in Example 1 of this invention (400 MHz, deuterated DMSO as solvent, tetramethylsilane as internal standard). Figure 4The carbon NMR spectrum of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one prepared in Example 1 of this invention (400 MHz, deuterated DMSO as solvent, tetramethylsilane as internal standard). Figure 5 In Example 3 of this invention, the excitation wavelength was 371 nm, and the concentration was 3.64 × 10⁻⁶. -3 mol L -1 CO3 was added dropwise to a solution of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one / ethanol. 2- The fluorescence emission spectrum, where the data indicated by the arrows represents the added CO3. 2- The concentration; Figure 6 The concentration in Example 4 of this invention is 3.64 × 10⁻⁶. -3 mol L -1 In a solution of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one / ethanol, with an excitation wavelength of 371 nm, the emission wavelength at 425 nm was measured, and the other anions' effects on CO32 were also measured. 2- A bar chart of fluorescence emission intensity from the interference experiment; Figure 7 In Example 5 of this invention, the excitation wavelength was 371 nm, the emission wavelength was 425 nm, and the concentration was 3.64 × 10⁻⁶. -3 mol L -1 Detection of CO3 in a solution of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one / ethanol 2- Linear relationship between relative fluorescence intensity I0 / I value and analyte concentration (C); Figure 8 In Example 6 of this invention, the excitation wavelength was 371 nm, and the concentration was 3.64 × 10⁻⁶. -3 mol L -1 PO4 was added dropwise to a solution of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one / ethanol. 3- The fluorescence emission spectrum is shown in the figure, with the data indicated by the arrows representing the added PO4. 3- The concentration; Figure 9 The concentration in Example 7 of this invention is 3.64 × 10⁻⁶. -3 mol L -1In a solution of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one / ethanol, with an excitation wavelength of 371 nm, the emission wavelength at 425 nm was measured, and the other anions were used to determine the PO4- ions. 3- A bar chart of fluorescence emission intensity from the interference experiment; Figure 10 In Example 8 of this invention, the excitation wavelength was 371 nm, the emission wavelength was 425 nm, and the concentration was 3.64 × 10⁻⁶. -3 mol L -1 Detection of PO4 in a solution of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one / ethanol 3- Linear relationship between relative fluorescence intensity I0 / I value and analyte concentration (C). Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0047] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0048] Example 1 A method for preparing a furanyloxadiazolone compound, the reaction process of which is shown below:

[0049] Where: TEA is the abbreviation for triethylamine; DCM is the abbreviation for dichloromethane; BTC is the abbreviation for triphosgene.

[0050] Specifically, the following steps are included: (1) Preparation of 5-nitrofuran-2-carboxylic acid: 15.7 g (0.1 mol) of 5-nitrofuran-2-carboxylic acid was placed in a 150 mL double-necked round-bottom flask equipped with a reflux condenser and dissolved in 40 mL of anhydrous dichloromethane. Oxaloyl chloride (16.51 g (0.13 mol)) was dissolved in 40 mL of dichloromethane and added dropwise to the double-necked round-bottom flask under magnetic stirring and at room temperature. After the addition was complete, the reaction was stirred for 1 hour at room temperature. After the reaction was completed, the solvent was removed by vacuum distillation, the solid was washed twice with diethyl ether, and dried to obtain 8.98 g of 5-nitrofuran-2-carboxylic acid solid. The product yield was 51.2% based on 5-nitrofuran-2-carboxylic acid.

[0051] (2) Synthesis of 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine: 2-hydrazinopyrimidine (4.40 g, 0.04 mol) and triethylamine (6.074 g, 0.06 mol) were placed in a 150 mL three-necked flask equipped with a reflux condenser and dissolved in 40 mL of dichloromethane. 5-nitrofuran-2-carboxyl chloride (8.424 g, 0.048 mol) was dissolved in 40 mL of dichloromethane and added dropwise to the above three-necked flask under magnetic stirring and nitrogen protection at 8 °C. After the addition was complete, the reaction was continued to be stirred at 8 °C for 2 hours. After the reaction was completed, the mixture was filtered, the filter cake was washed with double-distilled water, and dried to obtain 4.896 g of solid 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine. The product yield calculated based on 2-hydrazinopyrimidine was 49.12%.

[0052] (3) Synthesis of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one: 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine (3.735 g, 0.015 mol) and triethylamine (3.03 g, 0.030 mol) were placed in a 150 mL three-necked flask equipped with a reflux condenser and dissolved in 40 mL of dichloromethane. Triphosgene (5.342 g, 0.018 mol) was dissolved in 40 mL of dichloromethane and added dropwise to the above three-necked flask under magnetic stirring and nitrogen protection at 8 °C. After the addition was complete, the reaction was stirred at 8 °C for 2 hours. After the reaction was complete, the mixture was filtered, the filter cake was washed with double-distilled water, and dried to give 2.735 g of a white solid product, 5-(2-(5-nitrofuran)yl)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one, with a melting point of 201.1 °C. The yield, calculated based on 5-nitro-N'-(2-pyrimidinyl)furan-2-formylhydrazide, was 66.30%. The main infrared and nuclear magnetic resonance (NMR) data for 5-(2-(5-nitrofuran)yl)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one are as follows: IR: 3102 cm⁻¹-1 1530 cm -1 1348 cm -1 812 cm -1 . 1 H NMR (400 MHz, DMSO-d6) δ: 8.94 (d, 2H), 7.94 (d, 1H), 7.70 (d, 1H), 7.55 (t, 1H). 13 C NMR (400 MHz, DMSO-d6) δ: 159.76, 154.48, 153.04, 148.20, 145.33, 139.90, 120.41, 117.23, 114.41. Figure 1-4 It was deduced that the synthesized compound was the target substance.

[0053] Example 2 A method for preparing a furanyloxadiazolone compound includes the following steps: (1) Preparation of 5-nitrofuran-2-carboxylic acid: 15.7 g (0.1 mol) of 5-nitrofuran-2-carboxylic acid was placed in a 150 mL double-necked round-bottom flask equipped with a reflux condenser and dissolved in 40 mL of anhydrous dichloromethane. Oxaloyl chloride (15.24 g (0.12 mol)) was dissolved in 40 mL of dichloromethane and added dropwise to the double-necked round-bottom flask under magnetic stirring and at room temperature. After the addition was complete, the reaction was stirred for 2 hours at room temperature. After the reaction was completed, the solvent was removed by vacuum distillation, the solid was washed twice with diethyl ether, and dried to obtain 8.86 g of 5-nitrofuran-2-carboxylic acid solid. The product yield was 50.5% based on 5-nitrofuran-2-carboxylic acid.

[0054] (2) Synthesis of 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine: 2-hydrazinopyrimidine (4.40 g, 0.04 mol) and triethylamine (6.074 g, 0.06 mol) were placed in a 150 mL three-necked flask equipped with a reflux condenser and dissolved in 40 mL of dichloromethane. 5-nitrofuran-2-carboxyl chloride (10.53 g, 0.06 mol) was dissolved in 40 mL of dichloromethane and added dropwise to the above three-necked flask under magnetic stirring and nitrogen protection at 5 °C. After the addition was complete, the reaction was continued to be stirred at 5 °C for 3 hours. After the reaction was completed, the mixture was filtered, the filter cake was washed with double-distilled water, and dried to obtain 5.187 g of 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine solid. The product yield calculated based on 2-hydrazinopyrimidine was 52.04%.

[0055] (3) Synthesis of 5-(2-(5-nitrofuran)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one: 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine (3.735 g, 0.015 mol) and triethylamine (4.545 g, 0.045 mol) were placed in a 150 mL three-necked flask equipped with a reflux condenser and dissolved in 40 mL of dichloromethane. Triphosgene (5.979 g, 0.02 mol) was dissolved in 40 mL of dichloromethane and added dropwise to the above three-necked flask under magnetic stirring and nitrogen protection at 5 °C. After the addition was complete, the reaction was stirred at 5 °C for 3 hours. After the reaction was completed, the mixture was filtered, the filter cake was washed with double-distilled water, and dried to give 3.024 g of white solid product 5-(2-(5-nitrofuran)yl)-3-(2-pyrimidinyl)-1,3,4-oxadiazol-2(3H)-one with a melting point of 201.1 °C. The yield was 73.31% based on 5-nitro-N'-(2-pyrimidinyl)furan-2-formylhydrazide.

[0056] Example 3 The furanyloxadiazolone compound prepared in Example 1 was used as a fluorescent probe to detect low concentrations of CO3. 2- .

[0057] 4.0 mg of furanyloxadiazolone compound was added to ethanol solvent and ultrasonically dispersed to prepare a solution with a concentration of 3.64 × 10⁻⁶. -3 mol L -1 The solution was prepared as follows. 2 mL of the above solution was injected into a cuvette, and the fluorescence emission spectrum was measured using a Hitachi F-4500 fluorescence spectrometer at λex = 371 nm (excitation wavelength). Then, 5 µL of a prepared (0.01 mol / L) aqueous solution of potassium carbonate was added sequentially, and the fluorescence emission spectra of the solutions at the excitation wavelength of 371 nm were measured each time. The results are as follows. Figure 5 As shown, by Figure 5 It can be seen that with CO3 2- As the ion concentration increases, the fluorescence intensity of the solution decreases rapidly, especially when CO32- concentration increases. 2- The amount of ions added is 4×10 -4 moL L -1 At that time, the fluorescence emission intensity of the solution changed very little.

[0058] Example 4 4.0 mg of the furanyloxadiazolone compound prepared in Example 1 was added to an ethanol solvent and ultrasonically dispersed to prepare a solution with a concentration of 3.64 × 10⁻⁶. -3 mol L -1The solution was prepared by injecting 2 mL of the above solution into a cuvette and measuring the wavelength at λ using a Hitachi F-4500 fluorescence spectrometer with an excitation wavelength of 371 nm. em =Fluorescence intensity at 425nm (emission wavelength). Continue adding 200μL (0.01mol / L) of CO32-removing agent. 2- and PO4 3- For aqueous solutions of potassium salts other than those containing the anion, the fluorescence intensity of the solution containing the anion at the emission wavelength of 425 nm was measured, and the results are as follows: Figure 6 As shown in the figure, furanyloxadiazolone + other anions were added, followed by the addition of 200 µL (0.01 mol / L) of potassium carbonate aqueous solution. The emission wavelength λ of the mixed anion solution was then measured. em The fluorescence intensity at 425 nm is shown in the following results. Figure 6 furanyl oxadiazolone + other anions + CO3 2- As shown, by Figure 6 It can be seen that other anions (F) - NO3 - [Fe(CN)6] 3- I - SCN - SO4 2- CrO4 2- ,Br - ClO4 - HCO3 - Cl - MnO4 - Cr2O7 2- CO3 2- Fluorescence detection is virtually unaffected.

[0059] Example 5 Using the furanyloxadiazolone compound prepared in Example 1 as a fluorescent probe, the detection of CO3 by furanyloxadiazolone compound / ethanol solution was determined. 2- The relative fluorescence intensity I0 / I value of the ion and the detection of CO3 2- The relationship between concentration (C).

[0060] 4.0 mg of furanyloxadiazolone compound was added to ethanol solvent and ultrasonically dispersed to prepare a solution with a concentration of 3.64 × 10⁻⁶. -3 mol L -1The solution was prepared by adding 2 mL of the above solution to a cuvette and using a Hitachi F-4500 fluorescence spectrometer to excite the sample at λex = 371 nm (excitation wavelength) and measuring the fluorescence emission spectrum. Then, 15 µL, 20 µL, 25 µL, 35 µL, and 40 µL of a prepared potassium carbonate aqueous solution (0.01 mol / L) were added sequentially, and the fluorescence intensity at an emission wavelength of 425 nm (excitation wavelength of 371 nm) was measured respectively. The relative fluorescence intensity (I0 / I) was then calculated (I0 and I are CO32-, ... 2- Fluorescence intensity at concentrations of 0 and C, where C is in mol / L. -1 ) and CO3 2- The linear relationship between concentration (C) and measurement results are as follows: Figure 7 As shown in Table 1.

[0061] Table 1 shows the linear relationship between the I0 / I value of furanyloxadiazolone compound / ethanol solution and the concentration (C) of the analyte.

[0062] The relative fluorescence intensity (I0 / I) and CO3 measured above 2- The relationship between concentration (C) and concentration (C) indicates that at 7.5 × 10 -5 ~ 2.0×10 -4 mol L -1 Fluorescence intensity and CO3 within the range 2- The concentration showed a good linear relationship. This compound can be used as a fluorescent probe for the quantitative detection of low concentrations of CO3. 2- .

[0063] Example 6 The furanyloxadiazolone compound prepared in Example 1 was used as a fluorescent probe to detect low concentrations of PO4. 3- .

[0064] 4.0 mg of furanyloxadiazolone compound was added to ethanol solvent and ultrasonically dispersed to prepare a solution with a concentration of 3.64 × 10⁻⁶. -3 mol L -1 The solution was prepared as follows. 2 mL of the above solution was injected into a cuvette, and the fluorescence emission spectrum was measured using a Hitachi F-4500 fluorescence spectrometer at λex = 371 nm (excitation wavelength). Then, 2 µL of a prepared 0.01 mol / L potassium phosphate aqueous solution was added sequentially, and the fluorescence emission spectra of the solutions at the excitation wavelength of 371 nm were measured each time. The results are as follows. Figure 8 As shown, by Figure 8 It can be seen that with PO4 3- As the ion concentration increases, the fluorescence intensity of the solution decreases rapidly, especially when PO42-... 3- The amount of ions added was 2.0 × 10⁻⁶.-4 moL L -1 At that time, the fluorescence emission intensity of the solution changed very little.

[0065] Example 7 4.0 mg of the furanyloxadiazolone compound prepared in Example 1 was added to an ethanol solvent and ultrasonically dispersed to prepare a solution with a concentration of 3.64 × 10⁻⁶. -3 mol L -1 The solution was prepared by injecting 2 mL of the above solution into a cuvette and measuring the wavelength at λ using a Hitachi F-4500 fluorescence spectrometer with an excitation wavelength of 371 nm. em =Fluorescence intensity at 425nm (emission wavelength). Continue adding 200μL (0.01mol / L) of CO32-removing agent. 2- and PO4 3- For aqueous solutions of potassium salts other than those containing the anion, the fluorescence intensity of the solution containing the anion at the emission wavelength of 425 nm was measured, and the results are as follows: Figure 9 As shown in the figure, furanyloxadiazolone + other anions were added, followed by the addition of 200 µL (0.01 mol / L) of potassium phosphate aqueous solution. The emission wavelength λ of the mixed anion solution was then measured. em The fluorescence intensity at 425 nm is shown in the following results. Figure 9 furanyl oxadiazolone + other anions + PO4 3- As shown. By Figure 9 It can be seen that other anions (F) - NO3 - [Fe(CN)6] 3- I - SCN - SO4 2- CrO4 2- ,Br - ClO4 - HCO3 - Cl - MnO4 - Cr2O7 2- ) for PO4 3- Fluorescence detection is virtually unaffected.

[0066] Example 8 Using the furanyloxadiazolone compound prepared in Example 1 as a fluorescent probe, the detection of PO4 by furanyloxadiazolone compound / ethanol solution was determined. 3- The relative fluorescence intensity I0 / I value of ions and the detectant PO4 3- The relationship between concentration (C).

[0067] 4.0 mg of furanyloxadiazolone compound was added to ethanol solvent and ultrasonically dispersed to prepare a solution with a concentration of 3.64 × 10⁻⁶. -3 mol L -1 The solution was prepared by adding 2 mL of the above solution to a cuvette and using a Hitachi F-4500 fluorescence spectrometer to excite the sample at λex = 371 nm (excitation wavelength) and measuring the fluorescence emission spectrum. Then, 12 µL, 14 µL, 16 µL, 18 µL, and 20 µL of a prepared potassium phosphate aqueous solution (0.01 mol / L) were added sequentially, and the fluorescence intensity at an emission wavelength of 425 nm (excitation wavelength of 371 nm) was measured respectively. The relative fluorescence intensity (I0 / I) was then calculated (I0 and I are the PO42-phosphate dihydrogen phosphate concentrations, respectively). 3- Fluorescence intensity at concentrations of 0 and C, where C is in mol / L. -1 ) and PO4 3- The linear relationship between concentration (C) and measurement results are as follows: Figure 10 As shown in Table 2.

[0068] Table 2 shows the linear relationship between the I0 / I value of furanyloxadiazolone compound / ethanol solution and the concentration (C) of the analyte.

[0069] The relative fluorescence intensity (I0 / I) and PO4 measured above 3- The relationship between concentration (C) and concentration (C) indicates that at 6.0 × 10⁻⁶... -5 ~ 1.0×10 -4 mol L -1 Fluorescence intensity and PO4 within the range 3- The concentration showed a good linear relationship. This compound can be used as a fluorescent probe for the quantitative detection of low concentrations of PO4. 3- .

[0070] Comparative Example 1 Application number 202311792107, entitled "An Oxadiazolone Compound and Its Preparation Method and Its Application in the Detection of Fe..." 3+ A Chinese patent application document disclosing the application of this technology discloses a method for preparing an oxadiazolone compound by reacting 2-hydrazinopyrimidine with 4-nitrobenzoyl chloride to obtain 4-nitro-N'-(2-pyrimidinyl)benzoylhydrazine, followed by reaction with triphosgene. This compound is 5-(4-nitrophenyl)-3-(2-pyrimidinyl)-1,3,4'-oxadiazol-2(3H)-one, and only its fluorescence detection of Fe has been reported. 3+ Performance cannot detect PO4 3- .

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A furanyloxadiazolone compound, characterized in that: Its structural formula is shown below: 。 2. A method for preparing the furanyloxadiazolone compound as described in claim 1, characterized in that: Includes the following steps: S1. 5-Nitrofuran-2-carboxylic acid and oxaloyl chloride are reacted to obtain 5-nitrofuran-2-carboxylic chloride; S2. Acylation of 2-hydrazinopyrimidine with 5-nitrofuran-2-carboxyl chloride yields 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazide; S3. The furanyloxadiazolone compound is obtained by cyclizing 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine with triphosgene.

3. The method for preparing the furanyloxadiazolone compound according to claim 2, characterized in that, In S1, the reaction temperature is room temperature. In S2 and S3, the reaction temperature is controlled within the range of -5 to 10°C. The reaction solvents used are one or more of dichloromethane, trichloromethane, and carbon tetrachloride, and the reaction time is 2-4 hours.

4. The method for preparing the furanyloxadiazolone compound according to claim 2, characterized in that, In S1, the molar ratio of 5-nitrofuran-2-carboxylic acid to oxaloyl chloride is 1:1.2~1.5; in S2, the molar ratio of 2-hydrazinopyrimidine to 5-nitrofuran-2-carboxyl chloride is 1:1.2~2; in S3, the molar ratio of 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine to triphosgene is 1:1.2~1.

5.

5. The method for preparing the furanyloxadiazolone compound according to claim 2, characterized in that, In S2 and S3, triethylamine is added to carry out the reaction; in S2, the molar ratio of 2-hydrazinopyrimidine, triethylamine and 5-nitrofuran-2-carboxyl chloride is 1:1.5~3:1.2~2; in S3, the molar ratio of 5-nitro-N'-(2-pyrimidinyl)furan-2-carboxylhydrazine, triethylamine and triphosgene is 1:1~3:1.2~1.

5.

6. A furanyloxadiazolone compound as described in claim 1 for the detection of CO3 in water. 2- Or PO4 3- Applications in [the field].

7. The furanyloxadiazolone compound according to claim 6 in the detection of CO3 2- Or PO4 3- The application of this technology is characterized by: The furanyloxadiazolone compound is used as a fluorescent probe.

8. The furanyloxadiazolone compound according to claim 6 or 7 in the detection of CO3. 2- Or PO4 3- The application of this technology is characterized by: The furanyloxadiazolone compound was used as a fluorescent probe to detect CO3. 2- The concentration range is 7.5 × 10⁻⁶. -5 ~2.0×10 -4 mol L -1 .

9. The furanyloxadiazolone compound according to claim 6 in the detection of CO3 2- Or PO4 3- The application of this technology is characterized by: The furanyloxadiazolone compound was used as a fluorescent probe to detect PO4. 3- The concentration range is 6.0 × 10⁻⁶. -5 ~1.0×10 -4 mol L -1 .

10. The furanyloxadiazolone compound according to any one of claims 6-9 in the detection of CO3. 2- Or PO4 3- The application of this technology is characterized by: CO3 detection 2- At that time, the linear equation is I0 / I = 0.132 + 1.529 × 10 4 C; Detection of PO4 3- At that time, the linear equation is I0 / I = -0.868 + 3.892 × 10 4 C; where C is CO3 2- Or PO4 3- The concentration, in mol L -1 I0 and I are CO3 2- Or PO4 3- Fluorescence intensity at concentrations of 0 and C.

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