Tetracarboxylic acid organic ligand based on benzothiadiazole functional group for preparing metal organic framework as well as preparation method and application of tetracarboxylic acid organic ligand
By using tetracarboxylic acid organic ligand based on benzothiadiazole functional groups, a metal organic framework with a high conjugated structure and an electron donation framework was prepared, which solved the problem of insufficient detection sensitivity and selectivity of amine compounds in the prior art, and achieved efficient fluorescence detection effect.
Patent Information
- Application Number
- CN202510238180.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-03
- Publication Date
- 2025-06-03
AI Technical Summary
In the prior art, organic ligands used to prepare metal organic frameworks have problems of insufficient sensitivity and selectivity in fluorescent detection of amine compounds.
Using the tetracarboxylic acid organic ligand 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid based on the benzothiadiazole functional group, ligands with high conjugated structure and electron donating framework are formed through specific preparation methods and process steps, thereby enhancing the fluorescence intensity and selectivity of the metal organic framework.
Selective fluorescence detection of amine compounds is realized, the fluorescence intensity of the metal organic framework is enhanced, and the sensitivity and selectivity of detection are improved.
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Figure CN120081801A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of fluorescent sensing materials, and particularly relates to a quaternary carboxylic acid organic ligand based on a benzothiadiazole functional group for preparing metal-organic frameworks, a preparation method thereof, and an application thereof. Background Art
[0002] Metal-organic frameworks are organic-inorganic hybrid materials with permanent porosity formed by the self-assembly of metal ions or clusters and organic ligands through coordination bonds. In recent years, among metal-organic framework sensors, luminescent probes are considered to be highly efficient chemical probes due to their advantages such as simple structural composition, simple luminescence induction, and diverse detection mechanisms. Compared with other conventional fluorescent probes, luminescent metal-organic framework materials have well-organized chromophores, crystalline states, constant porous structures, and convertible characteristics. Generally, excellent luminescent metal-organic framework sensors have advantages such as high sensitivity, large detection range, excellent anti-interference ability, and good stability. The selection of organic ligands plays a decisive role in the luminescence of metal-organic frameworks. Even if there are no metal ions with characteristic luminescence in the framework, the strong luminescence of the ligand also endows the metal-organic framework with excellent luminescence characteristics. Currently, organic ligands with high conjugated π electrons are widely used in the research of functionalized luminescent metal-organic framework materials. Therefore, organic ligands are crucial in the design and synthesis of functional metal-organic frameworks.
[0003] Carboxylic acid ligands are one of the organic ligands commonly used in the synthesis of coordination polymers. According to the hard-soft acid-base theory, carboxylate is a hard base that can form strong coordination with metal ions, while metal ions belong to hard acids and are more likely to coordinate with carboxylate. Carboxylate has a negative charge, which can balance the positive charge of metal ions, making the pore channels of the constructed metal-organic framework electrically neutral, which is beneficial to improving the porosity and structural stability. In addition, the coordination modes of carboxylic acids are diverse, which is also beneficial to constructing metal-organic frameworks with rich structures. And 2,1,3-benzothiadiazole (BTD) is an important electron acceptor and is often used as an electron-deficient component of donor-acceptor polymers. It can be introduced as an electron-deficient unit into various small molecule structures to enrich the properties of molecules. In addition, BTD belongs to an important class of N, S heterocyclic compounds and has excellent optical properties. The planar rigidity and tunability of the structure are beneficial to constructing metal-organic frameworks. Therefore, polycyclic organic carboxylic acid ligands with BTD groups have potential application value in the preparation of luminescent properties. Summary of the Invention
[0004] The present invention provides a quaternary carboxylic acid organic ligand based on a benzothiadiazole functional group for preparing metal-organic frameworks and a preparation method thereof. The quaternary carboxylic acid organic ligand is 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid, and its molecular formula is C 22 H12 N 2 O 8 S, and this tetracarboxylic acid organic ligand can selectively detect amine compounds through fluorescence enhancement.
[0005] The present invention provides a tetracarboxylic acid organic ligand based on a benzothiadiazole functional group for preparing a metal-organic framework. The tetracarboxylic acid organic ligand based on the benzothiadiazole functional group is 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid, and its molecular formula is C 22 H 12 N 2 O 8 S.
[0006] The present invention also provides a preparation method of the above-mentioned tetracarboxylic acid organic ligand based on a benzothiadiazole functional group for preparing a metal-organic framework, including the following steps:
[0007] Step 1: Dissolve dimethyl 4-bromophthalate, pinacol borane, potassium acetate and 1,1''-bis(diphenylphosphino)ferrocene dichloropalladium in 1,4-dioxane, heat under reflux in a nitrogen atmosphere, extract successively with water and dichloromethane, dry over anhydrous sodium sulfate, filter, rotary evaporate and dry, and then purify by column chromatography to obtain the product dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate;
[0008] Step 2: Under nitrogen protection, take the dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate prepared in Step 1, 4,7-dibromo-2,1,3-benzothiadiazole, anhydrous potassium carbonate and tetrakis(triphenylphosphine)palladium, dissolve them in 1,4-dioxane, heat under reflux, and the obtained crude product is successively extracted with water and dichloromethane, rotary evaporated, dried, and then purified by column chromatography to obtain the product dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate;
[0009] Step 3: Dissolve the dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate prepared in Step 2 and sodium hydroxide in ethanol, heat under reflux, filter to obtain a filter residue, dissolve the filter residue in water, add concentrated hydrochloric acid dropwise and stir until a precipitate is formed, and successively filter, purify and dry to obtain the powdery product 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid.
[0010] Further, in Step 1, the molar ratio of dimethyl 4-bromophthalate, pinacol ester, and potassium acetate is 10:(10 - 20):40 mmol, the amount of substance of 1,1”-bis(diphenylphosphino)ferrocene dichloropalladium is 2% - 3% of the amount of substance of dimethyl 4-bromophthalate used, the amount of 1,4-dioxane used is 30 mL, the reaction temperature for heating under reflux is 95 °C, and the reaction time for heating under reflux is 72 h.
[0011] Further, in Step 1, the number of extraction times is three, and the conditions for column chromatography are as follows: silica gel is used as the stationary phase, dichloromethane / petroleum ether is used as the eluent, and the elution ratio is 2 / 1.
[0012] Further, in Step 2, the molar ratio of dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate, 4,7-dibromo-2,1,3-benzothiadiazole, and anhydrous potassium carbonate is (20 - 40):10:60 mmol, the amount of substance of tetrakis(triphenylphosphine)palladium is 12% - 15% of the amount of substance of 4,7-dibromo-2,1,3-benzothiadiazole used, the amount of 1,4-dioxane used is 130 mL, the reaction temperature for heating under reflux is 100 °C, and the reaction time for heating under reflux is 72 h.
[0013] Further, in Step 2, the number of extraction times is three, and the conditions for column chromatography are as follows: silica gel is used as the stationary phase, ethyl acetate / petroleum ether is used as the eluent, and the elution ratio is 1 / 2.
[0014] Further, in Step 3, the molar ratio of dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate and sodium hydroxide is 10:40 mmol, the amount of ethanol used is 45 mL, the reaction temperature for heating under reflux is 90 °C, and the reaction time for heating under reflux is 2 h.
[0015] Further, in Step 3, concentrated hydrochloric acid is added dropwise until the pH is 3 - 5, and the purification solvent is methanol.
[0016] The present invention also provides an application of the above-mentioned quaternary carboxylic acid organic ligand based on a benzothiadiazole functional group for preparing a metal-organic framework, and the quaternary carboxylic acid organic ligand based on a benzothiadiazole functional group is used for selectively fluorescently detecting amine compounds.
[0017] Further, the amine compound is any one of the following: ethylenediamine, polyamide, trimethylamine, methylamine, ethylamine, cyclohexylamine, tetramethylethylenediamine, and triethylamine.
[0018] The present invention has the following advantages compared with the prior art:
[0019] The present invention provides a quaternary carboxylic acid organic ligand 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid containing a benzothiadiazole functional group for preparing metal-organic frameworks and a preparation method thereof. The molecular structure of the quaternary carboxylic acid organic ligand contains four carboxyl groups and has a large conjugated structure and an electron-donating backbone, can selectively detect amine compounds through fluorescence enhancement, is used for preparing metal-organic frameworks, and can enhance the fluorescence intensity of the metal-organic frameworks. Description of the Drawings
[0020] Figure 1 is the structural diagram of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid;
[0021] Figure 2 is the nuclear magnetic resonance spectrum of dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate;
[0022] Figure 3 is the nuclear magnetic resonance spectrum of dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate;
[0023] Figure 4 is the nuclear magnetic resonance spectrum of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid;
[0024] Figure 5 is the infrared spectrum of dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate;
[0025] Figure 6 is the infrared spectrum of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid;
[0026] Figure 7 is the solid-state fluorescence excitation spectrum of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid;
[0027] Figure 8 is the solid-state fluorescence emission spectrum of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid;
[0028] Figure 9 is the CIE chromaticity diagram of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid;
[0029] Figure 10It is the sensitive fluorescence detection spectrogram of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl) diphthalic acid for amine compounds. Detailed implementation mode
[0030] Example 1
[0031] This example provides a preparation method of a quaternary carboxylic acid ligand containing a benzothiadiazole functional group for preparing a metal-organic framework. The specific steps are as follows:
[0032] Step 1: In a 250 mL three-necked flask, add 100 mL of 1,4-dioxane solvent, degas with nitrogen for 30 min. Under nitrogen protection, sequentially add 36.6 mmol of dimethyl 4-bromophthalate (10 g), 40.26 mmol of pinacol ester, 146.4 mmol of potassium acetate, and 1.1 mmol of catalyst 1,1”-bis(diphenylphosphino)ferrocene dichloropalladium. Reflux at 95 °C for 72 h. After the reaction is cooled to room temperature, a black-brown oily product is obtained. Extract it three times with a mixed solvent of water and dichloromethane, dry it with anhydrous sodium sulfate, and filter it. Retain the filtrate. After rotary evaporation, a crude product is obtained. Use a mixed solvent of dichloromethane:petroleum ether = 2:1 in a chromatography column to further purify the crude product. After rotary evaporation, cooling, and drying, 10.2 g of a white solid product, dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate, is obtained, with a yield of 87.05%;
[0033] Step 2: In a 250 mL three-necked flask, add 100 mL of 1,4-dioxane solvent, degas with N 2 for 1 h. Under N 2 protection, sequentially add 31.2 mmol of dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate (10 g), 7.8 mmol of 4,7-dibromo-2,1,3-benzothiadiazole, 46.8 mmol of anhydrous potassium carbonate, and 0.94 mmol of tetrakis(triphenylphosphine)palladium; The reaction mixture is refluxed at 100 °C for 72 h. After the reaction is completed, it is cooled to room temperature. The obtained crude product is extracted three times with a mixed solution of water and dichloromethane, and after rotary evaporation and drying, a crude product is obtained. Using silica gel as the stationary phase and ethyl acetate / petroleum ether as the eluent, with an elution ratio of 1 / 2, it is further purified by column chromatography. After rotary evaporation and drying, 3.69 g of a light yellow product, dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate, is obtained, with a yield of 90.89%;
[0034] Step 3: Add 6.72 mmol of dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate, 26.9 mmol of sodium hydroxide, and 30 mL of ethanol into a 100 mL flask. The mixture is refluxed at 90 °C for 2 h. After the reaction is completed, it is cooled to room temperature, filtered by suction and dried. The dried sample is dissolved in water, and concentrated HCl is added dropwise to adjust the solution to a pH value of 3 - 5. A yellow precipitate is precipitated under continuous stirring. The precipitate is filtered and purified with methanol, and then placed in an oven at 50 °C to dry overnight to obtain 2.5 g of yellow product 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid, with a yield of 80.11%.
[0035] The 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid prepared in this example is a quaternary carboxylic acid ligand based on benzothiadiazole functional groups for preparing metal-organic frameworks.
[0036] Example 2
[0037] This example provides a preparation method of a quaternary carboxylic acid ligand containing benzothiadiazole functional groups for preparing metal-organic frameworks. The specific steps are as follows:
[0038] Step 1: Add 30 mL of 1,4-dioxane solvent into a 100 mL three-necked flask, degas with nitrogen for 30 min. Under nitrogen protection, sequentially add 10 mmol of dimethyl 4-bromophthalate, 10 mmol of pinacol ester, 40 mmol of potassium acetate, and 0.2 mmol of catalyst 1,1”-bis(diphenylphosphino)ferrocene dichloropalladium. Reflux at 95 °C for 72 h. After the reaction is cooled to room temperature, a black-brown oily product is obtained. It is successively extracted three times with a mixed solvent of water and dichloromethane, dried with anhydrous sodium sulfate, and filtered by suction. The filtrate is retained. After rotary evaporation, a crude product is obtained. The crude product is further purified in a chromatography column using a mixed solvent of dichloromethane:petroleum ether = 2:1. After rotary evaporation, cooling, and drying, a white solid product dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate is obtained;
[0039] Step 2: Add 130 mL of 1,4-dioxane solvent into a 250 mL three-necked flask, degas for 1 h under N 2 degas for 1 h under N 2Under the protection state, 20 mmol of dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate, 10 mmol of 4,7-dibromo-2,1,3-benzothiadiazole, 60 mmol of anhydrous potassium carbonate and 1.2 mmol of tetrakis(triphenylphosphine)palladium were added successively; the reaction mixture was refluxed at 100 °C for 72 h, and after the reaction was completed, it was cooled to room temperature. The obtained crude product was extracted three times with a mixed solution of water and dichloromethane, and after rotary evaporation and drying, the crude product was obtained. Using silica gel as the stationary phase and ethyl acetate / petroleum ether as the eluent, the elution ratio was 1 / 2, and it was further purified by column chromatography. After rotary evaporation and drying, a light yellow product, dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate, was obtained;
[0040] In the third step, 10 mmol of dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate, 40 mmol of sodium hydroxide and 45 mL of ethanol were added to the flask. The mixture was refluxed at 90 °C for 2 h. After the reaction was completed, it was cooled to room temperature. After filtration and drying, the dried sample was dissolved in water, and concentrated HCl was added dropwise to adjust the solution to a pH value of 3-5. A yellow precipitate was precipitated with continuous stirring. The precipitate was filtered and purified with methanol, and then dried in an oven at 50 °C overnight to obtain the final product 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid.
[0041] The 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid prepared in this example is a quaternary carboxylic acid ligand based on a benzothiadiazole functional group for preparing metal-organic frameworks.
[0042] Example 3
[0043] This example provides a preparation method of a quaternary carboxylic acid ligand containing a benzothiadiazole functional group for preparing metal-organic frameworks. The specific steps are as follows:
[0044] Step 1: In a 100 mL three-necked flask, add 30 mL of 1,4-dioxane solvent, degas with nitrogen for 30 min. Under nitrogen protection, sequentially add 10 mmol of dimethyl 4-bromophthalate, 20 mmol of pinacol ester, 40 mmol of potassium acetate, and 0.3 mmol of the catalyst 1,1”-bis(diphenylphosphino)ferrocene dichloropalladium. Reflux at 95 °C for 3 days. After the reaction is cooled to room temperature, a black-brown oily product is obtained. Extract it three times with a mixed solvent of water and dichloromethane, dry it over anhydrous sodium sulfate, and filter it. Retain the filtrate. After rotary evaporation, a crude product is obtained. Further purify the crude product in a chromatography column using a mixed solvent of dichloromethane:petroleum ether = 2:1. After rotary evaporation, cooling, and drying, a white solid product, dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate, is obtained;
[0045] Step 2: In a 250 mL three-necked flask, add 100 mL of 1,4-dioxane solvent, degas with N 2 for 1 h. Under N 2 protection, sequentially add 30 mmol of dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate, 7.5 mmol of 4,7-dibromo-2,1,3-benzothiadiazole, 45 mmol of anhydrous potassium carbonate, and 1.1 mmol of tetrakis(triphenylphosphine)palladium. The reaction mixture is refluxed at 100 °C for 3 days. After the reaction is completed, cool it to room temperature. The obtained crude product is extracted three times with a mixed solution of water and dichloromethane. After rotary evaporation and drying, a crude product is obtained. Using silica gel as the stationary phase and ethyl acetate / petroleum ether as the eluent, with an elution ratio of 1 / 2, further purify it by column chromatography. After rotary evaporation and drying, a light yellow product, dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate, is obtained;
[0046] Step 3: In a 100 mL flask, add 10 mmol of dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate, 40 mmol of sodium hydroxide, and 45 mL of ethanol. The mixture is refluxed at 90 °C for 2 h. After the reaction is completed, cool it to room temperature. After filtration and drying, dissolve the dried sample in water, add concentrated HCl dropwise to adjust the solution to a pH value of 3 - 5. A yellow precipitate is precipitated with continuous stirring. After the precipitate is filtered and purified with methanol, it is placed in an oven at 50 °C and dried overnight to obtain the final product 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid.
[0047] The 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid prepared in this example is a tetracarboxylic acid ligand based on benzothiadiazole functional groups for preparing metal-organic frameworks.
[0048] Example 4
[0049] Characterize the obtained product 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid:
[0050] Take the tetracarboxylic acid ligand based on benzothiadiazole functional groups synthesized in Example 1 for preparing metal-organic frameworks and characterize it.
[0051] Figure 1 is the structural diagram of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid, and the molecular structure contains four carboxyl groups.
[0052] Figures 2 to 4 1H NMR data of dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate, dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate, and 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid, as well as the 1H NMR spectra of dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phthalate, dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate, and 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid were all collected by a Bruker AscendTM 400M nuclear magnetic resonance spectrometer.
[0053] Figure 2 in 1 1H NMR (400 MHz, CDCl 3 ) δ 8.15 (s, 1H), 7.95 (dd, J = 7.6, 0.9 Hz, 1H), 7.69 (d, J = 7.6 Hz, 1H), 3.89 (t, J = 10.4 Hz, 6H), 1.34 (s, 11H);
[0054] Figure 3 in 1 1H NMR (400 MHz, CDCl 3 ) δ 8.33 (d, J = 1.8 Hz, 1H), 8.21 (dd, J = 8.1, 1.9 Hz, 1H), 7.93 (d, J = 8.0 Hz, 1H), 7.88 (s, 1H), 3.97 (d, J = 2.1 Hz, 6H);
[0055] Figure 4 Middle 1 1H NMR(400 MHz, DMSO) δ 8.36 (d, J = 1.8 Hz, 1H), 8.24 (dd, J = 8.1, 1.9 Hz, 1H), 8.12 (s, 1H), 7.89 (d, J = 8.1 Hz, 1H);
[0056] Figures 5 - 6 It is the infrared spectrum of dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate and the organic ligand 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid prepared in Example 1 by a Bruker ALPHA FT-IR spectrometer.
[0057] Figure 5 In IR (KBr, cm -1 ): 3741w, 3609w, 3519w, 3448w, 3337m, 1726s, 1659m, 1594m, 1558m, 1440w, 1297s, 1192w, 1131w, 1058w, 859w, 772w, 677w, 542m.
[0058] Figure 6 In IR (KBr, cm -1 ): 3740m, 3611m, 3527w, 3446w, 3329s, 1706s, 1590m, 1550m, 1505m, 1388w, 1283m, 1143w, 1069w, 836w, 776w, 699w, 670w, 555w.
[0059] Figures 7 to 8 It is the solid-state fluorescence excitation and emission spectra of the ligand ground into powder collected by an F–4600 (Hitachi) fluorescence spectrometer (solid state), and the excitation and emission peaks are 370 nm and 510 nm, respectively, for 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid.
[0060] Figure 9 It is the CIE chromaticity diagram of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid.
[0061] Figure 10The detection data of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid for amine compounds were collected by an F–4600 (Hitachi) fluorescence spectrometer and plotted into a sensitive fluorescence detection spectrum. It can be seen that this organic ligand has specific recognition for ethylenediamine (EDA).
[0062] Other amine compounds were taken for corresponding detections. It can be known that 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid prepared in this example produces different fluorescence changes for ethylenediamine, polyamide, trimethylamine, methylamine, ethylamine, cyclohexylamine, tetramethylethylenediamine, and triethylamine. The addition of EDA enhances the fluorescence and causes a blue shift, while other amine substances cause a weak quenching of the fluorescence.
[0063] One or more embodiments of this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of this specification still fall within the protection scope of the technical solution of the present invention.
Claims
1. A tetracarboxylic acid organic ligand based on benzothiadiazole functional group for preparing a metal organic framework, characterized in that: The tetracarboxylic acid organic ligand based on the benzothiadiazole functional group is 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid, whose molecular formula is C 22 H 12 N2O8S.
2. A method for preparing a tetracarboxylic acid organic ligand based on a benzothiadiazole functional group for preparing a metal organic framework as claimed in claim 1, characterized in that: The following steps are involved: Step 1, dissolving dimethyl 4-bromophthalate, pinacol ester, potassium acetate and 1,1″-bis(diphenylphosphino)ferrocenepalladium dichloride in 1,4-dioxane, heating to reflux under a nitrogen atmosphere, extracting with water and dichloromethane in sequence, drying with anhydrous sodium sulfate and suction filtration, rotary evaporation and drying, and then purifying by column chromatography to obtain the product dimethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-diyl)phthalate; Step 2: Under nitrogen protection, dissolve the 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-diyl)phthalic acid dimethyl ester, 4,7-dibromo-2,1,3-benzothiadiazole, anhydrous potassium carbonate and tetrakis(triphenylphosphine)palladium prepared in step 1 in 1,4-dioxane, heat to reflux, and extract the obtained crude product with water and dichloromethane in turn, rotary evaporate, dry, and then purify by column chromatography to obtain the product 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid dimethyl ester; Step 3: dissolve the dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate and sodium hydroxide prepared in step 2 in ethanol, heat to reflux, filter to obtain a filter residue, dissolve the filter residue in water, add concentrated hydrochloric acid dropwise and stir until a precipitate is produced, filter, purify and dry in sequence to obtain a powdery product 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalic acid.
3. The preparation method according to claim 2, characterized in that: The molar ratio of dimethyl 4-bromophthalate, pinacol ester and potassium acetate in step 1 is 10: (10-20): 40 mmol, the molar amount of 1,1"-bis(diphenylphosphino)ferrocenepalladium dichloride is 2%-3% of the molar amount of dimethyl 4-bromophthalate used, the amount of 1,4-dioxane is 30 mL, the reaction temperature of heating and reflux is 95 ° C, and the reaction time of heating and reflux is 72 h.
4. The preparation method according to claim 2, characterized in that: The extraction times in step 1 are three times, and the column chromatography conditions are: silica gel as the stationary phase, dichloromethane / petroleum ether as the eluent, and the elution ratio is 2 / 1.
5. The preparation method according to claim 2, characterized in that: The molar ratio of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-diyl)phthalate, 4,7-dibromo-2,1,3-benzothiadiazole and anhydrous potassium carbonate in step 2 is (20-40):10:60 mmol, the amount of tetrakis(triphenylphosphine)palladium is 12%-15% of the amount of 4,7-dibromo-2,1,3-benzothiadiazole used, the amount of 1,4-dioxane is 130 mL, the reaction temperature of heating and reflux is 100° C., and the reaction time of heating and reflux is 72 h.
6. The preparation method according to claim 2, characterized in that: The extraction times in step 2 are three times, and the column chromatography conditions are: silica gel as the stationary phase, ethyl acetate / petroleum ether as the eluent, and the elution ratio is 1 / 2.
7. The preparation method according to claim 2, characterized in that: In step 3, the molar ratio of dimethyl 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphthalate to sodium hydroxide is 10:40 mmol, the amount of ethanol used is 45 mL, the reaction temperature of heating and reflux is 90° C., and the reaction time of heating and reflux is 2 h.
8. The preparation method according to claim 2, characterized in that: In step 3, concentrated hydrochloric acid is added dropwise until the pH value is 3-5, and the purification solvent is methanol.
9. A use of a tetracarboxylic acid organic ligand based on a benzothiadiazole functional group for preparing a metal organic framework as claimed in claim 1, characterized in that: The tetracarboxylic acid organic ligand based on benzothiadiazole functional group is used for selective fluorescence detection of amine compounds.
10. The use according to claim 9, characterized in that: The amine compound is any one of the following: ethylenediamine, polyamide, trimethylamine, methylamine, ethylamine, cycloethylamine, tetramethylethylenediamine and triethylamine.