Cucurbit [5] uril-based framework material as well as preparation method and application thereof

Abstract

The invention discloses a cucurbit [5] uril-based framework material as well as a preparation method and application thereof, and belongs to the crossing field of supramolecular chemistry and functional materials. The preparation method comprises the following steps: dissolving potassium salt and cucurbit [5] uril in distilled water; then adding a 3, 3 '-disulfo-[1, 1'-biphenyl]-4, 4 '-dicarboxylic acid ligand, and stirring to obtain a mixed solution; the mixed solution is subjected to a heating reaction, then cooling, filtering and drying are conducted, and the cucurbit [5] uril-based framework material is obtained, and the chemical formula is C396H360K18N180O198S18. Through coordination of an organic ligand containing a sulfonic acid group and metal ions, in combination with non-covalent interaction of hydrogen bonds, Van der Waals force and the like, and through optimal regulation and control of a material ratio, pH and temperature, a honeycomb three-dimensional porous framework structure with high stability is successfully constructed. By utilizing the fluorescence characteristic and the structural characteristic, the efficient recognition of Fe < 3 + > and Pb < 2 + > heavy metal ions and norfloxacin antibiotics in a water body can be realized. The problems that in the prior art, when heavy metal ions and antibiotics in water are detected, operation is tedious, and cost is high are solved.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of supramolecular chemistry and functional materials, specifically relating to a five-membered cucurbitacin-based framework material, its preparation method, and its applications. Background Technology

[0002] In industrial activities (such as mining, metal processing, and chemical manufacturing), heavy metal ions (mercury, lead, cadmium, etc.) enter the environment through waste gas, wastewater, and waste residue. They seep into groundwater through water bodies and soil, and diffuse through the water and atmospheric cycles, causing pollution. Their high toxicity, persistence, and accumulation make them difficult to degrade naturally, accumulating through the food chain and harming the nervous and immune systems; lead significantly impacts children's intellectual development. Simultaneously, antibiotic residues (such as norfloxacin) disrupt the aquatic ecological balance, induce bacterial resistance, and increase the difficulty of treating infections.

[0003] Traditional detection methods (AAS, ICP-OES, ICP-MS) are accurate but complex to operate, expensive to use, and have high operating costs, limiting their application in primary and field testing. Fluorescence sensing technology achieves rapid detection through changes in fluorescence signals (intensity, wavelength), and has advantages such as high sensitivity (detection limit down to the nanogram level), high selectivity, real-time operation, and ease of use. However, there are few reports on stable materials that can simultaneously detect heavy metals and antibiotics.

[0004] Therefore, it is necessary to develop a method that can selectively identify Fe in water. 3+ Pb 2 The five-membered cucurbitacin framework material and fluorescent probe for + and norfloxacin (NFX) help fill the gap in this field, providing a rapid, sensitive and convenient new approach for water pollution detection, which is of great significance to ecological protection and human health. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a five-membered cucurbit ring-based framework material, its preparation method, and its application, thereby solving the problems in the prior art.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a five-membered cucurbit ring-based framework material includes the following steps:

[0008] Dissolve the potassium salt and the five-membered cucurbit ring in distilled water; then add 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid ligand and stir to obtain a mixture.

[0009] The mixture was heated and the pH was adjusted. After the reaction was completed, it was cooled, filtered, and dried to obtain a five-membered cucurbitacin-based framework material with the chemical formula C. 396 H 360 K 18 N180 O 198 S 18 .

[0010] Furthermore, in the five-membered cucurbita ring-based framework material, the molar ratio of potassium ions, the five-membered cucurbita ring, and the 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid ligand is 2:1:1.

[0011] Furthermore, the potassium salt is any one of KCl, KNO3, and K2SO4.

[0012] Furthermore, the conditions for the heating reaction are as follows:

[0013] First, heat the mixture to 120℃ and hold it at that temperature for 10 hours, then increase the temperature by 1℃ for 10 minutes. -1 Cool down to 25℃ at a rapid rate and hold at that temperature for 12-24 hours;

[0014] Alternatively, heat under reflux in an oil bath at 80°C for 4 hours.

[0015] Furthermore, the pH adjustment range is 6-8.

[0016] A five-membered cucurbit ring-based framework material was prepared using the above-described preparation method.

[0017] Application of the aforementioned five-membered cucurbitacin-based framework material in the detection of heavy metal ions and antibiotics in water; the heavy metal ion is Fe. 3+ and Pb 2+ The antibiotic in question is norfloxacin.

[0018] A method for preparing a fluorescent probe includes: grinding the above-mentioned five-membered cucurbitacin framework material, dissolving it in distilled water to obtain a concentration of 1 mg·mL⁻¹. -1 The solution is the fluorescent probe.

[0019] A fluorescent probe was prepared using the method described above.

[0020] A method for detecting Fe in water 3+ Pb 2+ And the NFX method, using the above-described fluorescent probe, characterized in that it includes:

[0021] 1) Record the fluorescence spectrum generated by the fluorescent probe at an excitation wavelength of 235 nm;

[0022] 2) Containing Fe 3+ Pb 2+ Alternatively, a single aqueous solution of NFX can be added to the fluorescent probe, and the fluorescence spectrum generated by the fluorescent probe at an excitation wavelength of 235 nm can be recorded.

[0023] 3) Compare the changes in fluorescence spectra before and after emission at the maximum emission wavelength of 383 nm, and their effect on Fe in water. 3+ Pb 2+ Alternatively, NFX can be used for detection.

[0024] The beneficial effects of this invention are:

[0025] 1. This invention provides a method for preparing a five-membered cucurbit ring-based framework material, which is simple to operate and has a high yield. Through the coordination of sulfonic acid-containing organic ligands with metal ions, combined with non-covalent interactions such as hydrogen bonds and van der Waals forces, and through optimized control of material ratio, pH, and temperature, a highly stable "honeycomb" three-dimensional porous framework structure was successfully constructed. This design fully utilizes the multiple forces between the sulfonic acid groups of the organic ligands and the cucurbit ring matrix, achieving precise construction and performance optimization of the framework material's pore structure through synergistic thermodynamic and kinetic control.

[0026] 2. In this invention, a fluorescent probe is configured using a five-membered cucurbitacin-based framework material, and is used for the detection of Fe in water. 3+ and Pb 2 + Heavy metal ions and norfloxacin (NFX) antibiotics are characterized by convenient and quick operation, good selectivity, low detection limit, and reusability. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the crystal structure of the five-membered cucurbit ring-based framework material of the present invention;

[0029] Figure 2 This is a structural characterization diagram of the five-membered cucurbit ring-based framework material of the present invention;

[0030] Figure 3 This is a thermogravimetric (TG) characterization diagram of the five-membered cucurbit ring-based framework material of the present invention;

[0031] Figure 4 The graph shows the changes in fluorescence intensity before and after adding 1M standard solutions of different metal ions to the fluorescent probe.

[0032] Figure 5 For fluorescent probes containing Fe 3+ Fluorescence titration chromatogram of aqueous solution;

[0033] Figure 6 For fluorescent probes containing Pb 2+Fluorescence titration chromatogram of aqueous solution;

[0034] Figure 7 The graph shows the changes in fluorescence intensity before and after adding 1M standard solutions of different antibiotics to the fluorescent probe.

[0035] Figure 8 This is a fluorescence titration diagram of the fluorescent probe on an aqueous solution containing NFX. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0037] A method for preparing a five-membered cucurbit ring-based framework material includes the following steps:

[0038] S1, dissolve potassium salt and five-membered cucurbita ring (Q[5]) in distilled water to form a transparent solution; then add 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid ligand (H4L) and stir evenly to obtain a mixed solution;

[0039] S2, the mixture is heated to adjust the pH to 6-8 (by adding ammonia), thereby dissolving the 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid ligand and the five-membered cucurbitacin-K ligand in the mixture. + A five-membered cucurbit ring-based framework material was obtained through self-assembly. After the reaction was completed, the material was cooled, filtered, and dried to obtain the five-membered cucurbit ring-based framework material.

[0040] In S1, n(K) + ):n(Q[5]):n(H4L)=2:1:1; the potassium salt is any one of KCl, KNO3, and K2SO4.

[0041] In S2, the heating reaction conditions are as follows: first, heat the mixture to 120℃ and hold it at that temperature for 10 hours, then heat it at 1℃ for 10 minutes. -1 The rate of cooling is reduced to 25°C, and the temperature is maintained for 12-24 hours. Alternatively, the reaction conditions can be: reflux at 80°C in an oil bath for 4 hours.

[0042] Among them, the chemical formula of the five-membered cucurbit ring-based framework material is: C 396 H 360 K 18 N 180 O 198 S 18 The molecular weight is 12089.11. The structural diagram is shown below. Figure 1 As shown, the repeating basic units are: Q[5], 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid, and K. + .

[0043] The technical solution of the present invention will be described below through the following embodiments: In the embodiments, the synthesized five-membered cucurbitacin-based framework material was characterized by X-ray single-crystal diffraction, PXRD powder diffraction, DSC-TG and other analytical methods. Fluorescence spectroscopy was used to study its ability to detect Fe in aqueous solution. 3+ and Pb 2+ Heavy metal ions and the properties of norfloxacin (NFX) antibiotics.

[0044] Example 1

[0045] A method for preparing a five-membered cucurbit ring-based framework material, the process of which is as follows:

[0046] Weigh Q[5] (35.2 mg, 0.03 mmol) and excess KCl (894.6 mg, 0.12 mmol); place it in a reagent tube containing 10 mL of distilled water, and sonicate for 10 min to completely dissolve Q[5] and KCl to obtain a clear and transparent solution. Add 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid (12.03 mg, 0.03 mmol) to the above clear solution, dissolve, and sonicate for 20 min to obtain a mixture, and then adjust the pH to 6-8 with NH3·H2O. Place it in a high-pressure reactor, first heat the mixture to 120℃, keep it at a constant temperature for 10 h, and then heat it at 1℃·10 min. -1 The temperature was gradually reduced to 25°C, the programmed temperature rise oven was turned off, and the high-pressure reactor was allowed to cool to room temperature. After standing for 24 hours, the mixture was directly filtered to obtain colorless blocky crystals. The yield was 35-45%; in the product, n(K) + ):n(Q[5]):n(H4L)=2:1:1, when raw materials are added, K + It is excessive.

[0047] The structural characterization of the colorless bulk crystal (a five-membered cucurbit ring-based framework material) is shown in [reference needed]. Figure 1 and Figure 2 The results showed that the obtained sample was a pure phase; thermogravimetric analysis is shown in [reference needed]. Figure 3 It can be seen that the thermal stability of the material reaches 400℃, which is higher than that of cucurbitacin.

[0048] Example 2

[0049] A method for preparing a five-membered cucurbit ring-based framework material, the process of which is as follows:

[0050] Weigh Q[5] (35.2 mg, 0.03 mmol) and KCl (894.6 mg, 0.12 mmol). Place them in a reagent tube containing 10 mL of distilled water and sonicate for 10 min to completely dissolve Q[5] and KCl to obtain a clear and transparent solution. Then add 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid (12.03 mg, 0.03 mmol) to the above clear solution, dissolve it, and then add it to the above solution. Adjust the pH to 6-8 with NH3·H2O, sonicate for 20 min to obtain a mixed solution. Heat the above mixed solution under reflux in an oil bath at 80℃ for 4 hours (simple method), cool and filter, wash the precipitate with deionized water, and dry to obtain the desired five-membered cucurbitacin-based framework material with a yield of 72% (where n(K + ):n(Q[5]):n(H4L)=2:1:1).

[0051] In this embodiment, the synthesized material was characterized by powder PXRD. Figure 2 The presence of α indicates that it has a high degree of crystallinity, and the main peaks match the simulated peaks of the crystal structure, indicating that it is a pure phase.

[0052] Example 3

[0053] This embodiment describes the preparation process of a fluorescent probe made of a five-membered cucurbit ring-based framework material:

[0054] Weigh 50 mg of the sample (pentacyclic cucurbitacin-based framework material) obtained in Example 1, grind it thoroughly, add 10 mL of distilled water, sonicate for 30 min, and then transfer it to a 50 mL volumetric flask and make up to volume to obtain a concentration of 1 mg / mL. -1 Fluorescent probe solution.

[0055] Example 4

[0056] This embodiment describes the use of the fluorescent probe from Example 3 in the detection of heavy metals (Fe) in water. 3+ Pb 2+ Methods for determining the concentration of antibiotics (norfloxacin).

[0057] (1) Determination of Fe in water 3+ ;

[0058] The specific procedure is as follows: Take a quartz glass dish, add 2 mL of a 1 mg / mL fluorescent probe solution, fix the excitation wavelength at 235 nm, and measure the fluorescence spectrum in the range of 255-450 nm. Then, add 1 M Fe... 3+After obtaining the standard solution, stir the suspension at a constant rate to ensure homogeneity. Measure a series of fluorescence curves until the ordinate of the fluorescence curve changes slowly; at this point, the titration operation can be stopped. Using the probe fluorescence emission intensity at 320 nm, apply the nonlinear Stern-Volmer equation I0 / I=Ae k[Q] +B (where I0 and I are the fluorescence emission intensities of the suspension before and after adding FeCl3 solution, respectively; A, B, and k are constants; and Q is the ion concentration) are fitted and then based on K SV =A×k Calculate the quenching constant and the standard deviation σ of 5 blank values. According to the formula, the limit of detection DL = 3σ / K SV Calculate the detection of Fe-containing fluorescent probes 3+ The detection limit of the standard solution.

[0059] (2) Determination of Pb in water 2+ ;

[0060] The specific procedure is as follows: Take a quartz glass dish, add 2 mL of a 1 mg / mL fluorescent probe solution, fix the excitation wavelength at 235 nm, and measure the fluorescence spectrum in the range of 255-450 nm. Then, add 1 M Pb-containing solution dropwise. 2+ After obtaining the standard solution, stir the suspension at a constant rate to ensure homogeneity. Measure a series of fluorescence curves until the ordinate of the fluorescence curve changes slowly; at this point, the titration operation can be stopped. Using the probe fluorescence emission intensity at 320 nm, apply the nonlinear Stern-Volmer equation I0 / I=Ae k[Q] +B (where I0 and I are the fluorescence emission intensities of the suspension before and after adding PbCl2 solution, respectively; A, B, and k are constants; and Q is the ion concentration) are fitted and then based on K SV =A×k Calculate the quenching constant and the standard deviation σ of 5 blank values. According to the formula, the limit of detection DL = 3σ / K SV Calculate the detection of Pb-containing fluorescent probes. 2+ The detection limit of the standard solution.

[0061] in:

[0062] Figure 4 The changes in fluorescence intensity before and after the fluorescent probe was added to 1M standard solutions of different metal ions were demonstrated. It can be seen that the five-membered cucurbitacin-based framework material synthesized in Example 1 exhibits resistance to Fe when in contact with a series of metal ion solutions. 3+ and Pb 2 The material exhibits highly selective fluorescence quenching response, with quenching efficiencies reaching 90% and 75%, respectively. This demonstrates its significant potential as a "turn-off" fluorescent probe, particularly in the field of environmental pollutant detection.

[0063] Fluorescent probes for Fe 3+ The fluorescence titration chromatogram of the aqueous solution is shown below. Figure 5 As shown, fluorescence titration analysis indicates that the framework material prepared in Example 1 is effective against Fe. 3+ The ions exhibit a significant concentration-dependent fluorescence quenching effect. With the increase of Fe... 3+ As the ion concentration gradient increases, the characteristic fluorescence emission intensity of the material at 383 nm exhibits a regular decrease, especially when Fe... 3+ When the ion concentration reaches 100 μM, the quenching efficiency can reach 99.38%, and the detection limit is 3.75 × 10⁻⁶. -7 M. This linear response characteristic (R) 2 =0.999) confirms that this material can be used as a highly sensitive "turn-off" fluorescent probe in environmental water samples containing Fe 3+ It has potential applications in the field of ion detection.

[0064] Fluorescent probes for Pb-containing 2+ The fluorescence titration chromatogram of the aqueous solution is shown below. Figure 6 As shown, fluorescence titration analysis indicates that the framework material prepared in Example 1 is effective against Pb. 2+ The ions exhibit a significant concentration-dependent fluorescence quenching effect. With the increase of Pb... 2+ As the ion concentration gradient increases, the characteristic fluorescence emission intensity of the material at 383 nm exhibits a regular decrease, especially when Pb... 2+ When the ion concentration reaches 100 μM, the quenching efficiency can reach 68.95%, and the detection limit is 1.15 × 10⁻⁶. -6 M. This linear response characteristic (R) 2 =0.996) confirms that this material can serve as a highly sensitive "turn-off" fluorescent probe for Pb in environmental water samples. 2+ It has potential applications in the field of ion detection.

[0065] (3) Determination of norfloxacin (NFX) in water;

[0066] The specific procedure is as follows: Take a quartz glass dish, add 2 mL of a 1 mg / mL fluorescent probe solution, fix the excitation wavelength at 235 nm, and measure the fluorescence spectrum in the range of 255-450 nm. Next, add a 1 M standard solution containing norfloxacin (NFX) dropwise, stirring the suspension at a constant rate to ensure homogeneity. Measure a series of fluorescence curves until the ordinate of the fluorescence curve changes slowly, at which point the titration operation can be stopped. Using the probe fluorescence emission intensity at 320 nm, apply the nonlinear Stern-Volmer equation I0 / I=Ae k[Q]+B (where I0 and I are the fluorescence emission intensities of the suspension before and after adding NFX solution, respectively; A, B, and k are constants; and Q is the concentration of NFX) are fitted and then based on K SV =A×k Calculate the quenching constant and the standard deviation σ of 5 blank values. According to the formula, the limit of detection DL = 3σ / K SV The detection limit of the fluorescent probe for detecting standard solutions containing NFX was calculated.

[0067] in, Figure 7 The changes in fluorescence intensity before and after the fluorescent probe was added to 1M standard solutions of different antibiotics were demonstrated. It can be seen that the five-membered cucurbitacin framework material synthesized in Example 1 exhibits highly selective fluorescence quenching response to norfloxacin (NFX) upon contact with a series of antibiotic solutions. This phenomenon indicates that the material possesses significant potential as a "turn-off" fluorescent probe, especially in the field of environmental pollutant detection.

[0068] The fluorescence titration chromatogram of the fluorescent probe against the NFX-containing aqueous solution is shown in Figure 8. It can be seen that the fluorescence titration analysis indicates that the framework material prepared in Example 1 exhibits a significant concentration-dependent fluorescence quenching effect on the antibiotic norfloxacin (NFX). With increasing norfloxacin (NFX) concentration, the characteristic fluorescence emission intensity of the material at 383 nm shows a regular decrease. When the norfloxacin (NFX) concentration reaches 100 μM, the quenching efficiency reaches 70.62%, and the detection limit reaches 1.84 × 10⁻⁶. - 6 M. This linear response characteristic (R) 2 =0.997) confirms that this material can be used as a highly sensitive "turn-off" fluorescent probe, and has potential application value in the detection of the antibiotic norfloxacin (NFX) in environmental water samples.

[0069] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0070] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a five-membered cucurbit ring-based framework material, characterized in that, Includes the following steps: Dissolve the potassium salt and the five-membered cucurbit ring in distilled water; then add 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid ligand and stir to obtain a mixture. The mixture was heated and the pH was adjusted. After the reaction was completed, it was cooled, filtered, and dried to obtain a five-membered cucurbitacin-based framework material with the chemical formula C. 396 H 360 K 18 N 180 O 198 S 18 .

2. The method for preparing a five-membered cucurbit ring-based framework material according to claim 1, characterized in that, In the five-membered cucurbita ring-based framework material, the molar ratio of potassium ions, five-membered cucurbita rings, and 3,3'-disulfonyl-[1,1'-biphenyl]-4,4'-dicarboxylic acid ligands is 2:1:

1.

3. The method for preparing a five-membered cucurbit ring-based framework material according to claim 1, characterized in that, The potassium salt is any one of KCl, KNO3, and K2SO4.

4. The method for preparing a five-membered cucurbit ring-based framework material according to claim 1, characterized in that, The conditions for the heating reaction are: First, heat the mixture to 120℃ and hold it at that temperature for 10 hours, then increase the temperature by 1℃ for 10 minutes. -1 Cool down to 25℃ at a rapid rate and hold at that temperature for 12-24 hours; Alternatively, heat under reflux in an oil bath at 80°C for 4 hours.

5. The method for preparing a five-membered cucurbit ring-based framework material according to claim 1, characterized in that, The pH range for adjustment is 6-8.

6. A five-element cucurbit ring-based framework material, characterized in that, Prepared using the preparation method described in any one of claims 1-5.

7. The application of the five-membered cucurbitacin-based framework material of claim 6 in the detection of heavy metal ions and antibiotics in water; wherein the heavy metal ion is Fe. 3+ and Pb 2+ The antibiotic in question is norfloxacin.

8. A method for preparing a fluorescent probe, characterized in that, include: After grinding the five-membered cucurbit ring-based framework material as described in claim 6, it was dissolved in distilled water to obtain a concentration of 1 mg·mL⁻¹. -1 The solution is the fluorescent probe.

9. A fluorescent probe, characterized in that, It was prepared using the preparation method described in claim 8.

10. A method for detecting Fe in water 3+ Pb 2+ And the NFX method, using the fluorescent probe of claim 9, characterized in that, include: 1) Record the fluorescence spectrum generated by the fluorescent probe at an excitation wavelength of 235 nm; 2) Containing Fe 3+ Pb 2+ Alternatively, a single aqueous solution of NFX can be added to the fluorescent probe, and the fluorescence spectrum generated by the fluorescent probe at an excitation wavelength of 235 nm can be recorded. 3) Compare the changes in fluorescence spectra before and after emission at the maximum emission wavelength of 383 nm, and their effect on Fe in water. 3+ Pb 2+ Alternatively, NFX can be used for detection.

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