Pyridine group functionalized column [5] arene or salt thereof, and preparation method and application thereof

Abstract

The invention belongs to the technical field of water body detection, and particularly relates to pyridine group functionalized column [5] arene or salt thereof as well as a preparation method and application of the pyridine group functionalized column [5] arene. The pyridine group functionalized column [5] arene or the salt thereof has excellent binding capacity with fluorescein sodium, and the binding capacity is far higher than that of the pyridine group functionalized column [5] arene or the salt thereof with other fluorescent indicators (such as sunset yellow, rhodamine B, acridine orange G and the like); the binding capacity is higher than that of other different modified column [5] arene (such as P5A, P5B or P5CA) and fluorescein sodium; moreover, the binding constant of the fluorescein sodium and the pyridine group functionalized column [5] arene or the salt thereof can reach 8.60 * 10 < 5 > M <-1 >, which indicates that the complexing stability of the pyridine group functionalized column [5] arene and the fluorescein sodium is high, and the fluorescent probe formed by combining the pyridine group functionalized column [5] arene and the fluorescein sodium has very high stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of water body detection, and specifically relates to pyridine group-functionalized pillar[5]arene or its salt, and a preparation method and application thereof. Background Art

[0002] Per- and polyfluoroalkyl substances (PFAS) have become persistent pollutants of global concern due to the high stability and bioaccumulation of their carbon-fluorine chains. These substances are difficult to remove through conventional pathways such as photolysis, hydrolysis, or biodegradation, and can accumulate through the food chain, causing irreversible damage to human organs such as the liver and kidneys. Although the detection demand for PFAS is urgent, their chemical inertness results in insufficient sensitivity of traditional detection methods such as color development and precipitation (the detection limit is usually higher than 1 ppm), and there is an urgent need to develop efficient and highly selective detection technologies.

[0003] Current PFAS detection mainly relies on triple quadrupole liquid chromatography-mass spectrometry (LC-MS / MS). This method requires complex pretreatment (such as solid-phase extraction and ion-pair reagent derivatization), the detection time for a single sample is as long as 4-6 hours, and the equipment purchase and maintenance costs are high (about 500,000 US dollars per unit), and strict requirements are imposed on the professionalism of operators. In addition, matrix effects and isotope internal standard dependence may lead to quantitative errors, making it difficult to meet the detection needs of on-site rapid screening or resource-limited areas.

[0004] Supramolecular chemistry realizes molecular specific recognition through host-guest interactions, providing a new path for PFAS detection. Early host materials such as cyclodextrin and calixarene have limited binding ability to long-chain PFAS (such as PFOS chain length 1.1 nm - 1.4 nm) due to cavity size limitations (for example, the pore diameter of β-cyclodextrin is 0.6 nm - 0.8 nm) (binding constant Ka < 10^4 M-1). In recent years, pillar[n]arene has shown potential in the field of supramolecular sensing due to its rigid extended cavity (diameter up to 1.3 - 1.5 nm) and rich modification sites (such as phenolic hydroxyl edges): its cavity size and hydrophobic interaction can adapt to long-chain molecules, and its modification flexibility is higher than that of traditional materials such as crown ethers and cucurbiturils. However, existing research has mostly focused on the recognition of alkanes or metal ions by pillar[n]arene, and its application in PFAS detection still faces bottlenecks such as the lack of signal response mechanism (such as the lack of an effective fluorescence labeling strategy) and insufficient selectivity. Summary of the Invention

[0005] In order to achieve the above object, the present invention can adopt the following technical solutions:

[0006] The present invention provides a pyridine group-functionalized pillar[5]arene or its salt on the one hand. The structural formula of the pyridine group-functionalized pillar[5]arene is shown as follows:

[0007]

[0008] On the other hand, the present invention also provides a method for preparing the pyridine group-functionalized pillar[5]arene in the present invention, comprising:

[0009] (1) Reacting 1,4-bis(2-bromobutoxy)benzene, an aldehyde group condensation reagent and a Lewis acid catalyst to obtain bromobutoxy-modified pillar[5]arene;

[0010] (2) Reacting the bromobutoxy-modified pillar[5]arene with pyridine to obtain a pyridine group-functionalized pillar[5]arene.

[0011] On yet another aspect, the present invention provides a fluorescent probe, which comprises sodium fluorescein and the pyridine group-functionalized pillar[5]arene or its salt in the present invention, and the sodium fluorescein is within the cavity of the pyridine group-functionalized pillar[5]arene or its salt.

[0012] Preferably, in the above-mentioned fluorescent probe, the molar concentration ratio of sodium fluorescein to the pyridine group-functionalized pillar[5]arene is (0.7 - 0.9):1.

[0013] On yet another aspect, the present invention provides a method for preparing the fluorescent probe in the present invention, comprising: mixing an aqueous solution of sodium fluorescein and a solution of the pyridine group-functionalized pillar[5]arene to obtain the fluorescent probe.

[0014] On yet another aspect, the present invention provides a detection reagent or kit, which comprises the fluorescent probe in the present invention.

[0015] On yet another aspect, the present invention provides an application of the fluorescent probe in the present invention in detecting a compound, wherein the binding constant of the compound with the pyridine group-functionalized pillar[5]arene > the binding constant of sodium fluorescein with the pyridine group-functionalized pillar[5]arene.

[0016] Preferably, in the above application, the compound is a perfluoro and polyfluoroalkyl compound.

[0017] Preferably, in the above application, the perfluoro and polyfluoroalkyl compound is selected from perfluorooctanoic acid (PFOA) and / or perfluorooctane sulfonic acid (PFOS).

[0018] On yet another aspect, the present invention provides a method for detecting perfluoro and polyfluoroalkyl compounds in water, comprising: (1) constructing a concentration-fluorescence intensity standard curve by using a standard solution of a perfluoro and polyfluoroalkyl compound with a known concentration and the fluorescent probe in the present invention; detecting the fluorescence intensity of the water to be detected by using the fluorescent probe; (2) calculating the concentration of the perfluoro and polyfluoroalkyl compound in the water according to the fluorescence intensity and the concentration-fluorescence intensity standard curve.

[0019] The beneficial effects of the present invention include:

[0020] (1) The pyridine group-functionalized pillar[5]arene or its salt in the present invention has excellent binding ability with sodium fluorescein, and its binding ability is much stronger than that with other fluorescent indicators (such as sunset yellow, rhodamine B, and acridine orange G, etc.), and also stronger than that of other differently modified pillar[5]arenes (such as P5A, P5B, or P5CA) with sodium fluorescein; moreover, the binding constant of sodium fluorescein and the pyridine group-functionalized pillar[5]arene or its salt can reach 8.60×10 5 M -1 , indicating that the pyridine group-functionalized pillar[5]arene has high complexation stability with sodium fluorescein, and the fluorescent probe formed by their combination has high stability.

[0021] (2) The pyridine group-functionalized pillar[5]arene in the present invention has excellent binding ability with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) respectively. For example, the binding constant with PFOA can reach 8.70×10 5 M -1 , and the binding constant with PFOS reaches 1.59×10 6 M -1 .

[0022] (3) The pyridine group-functionalized pillar[5]arene in the present invention can specifically recognize and form host-guest complexation with PFOA and PFOS. The process is extremely rapid. Compared with the traditional detection using LC-MS / MS, the detection time can be significantly shortened, fully ensuring the timeliness of the detection results.

[0023] (4) The pyridine group-functionalized pillar[5]arene in the present invention can specifically bind with PFOA and PFOS. Therefore, the complex pretreatment process during the detection using LC-MS / MS can be avoided, reducing the operation difficulty and minimizing the influence brought by the matrix effect as much as possible, making the detection more convenient, rapid, and accurate.

[0024] (5) The preparation method of the pyridine group-functionalized pillar[5]arene in the present invention is simple and the product is single. It can be applied to large-scale synthesis and used for the detection of water samples, with high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the 1H NMR spectrum of the pyridine group-functionalized pillar[5]arene;

[0026] Figure 2 is the binding situation of the pyridine group-functionalized pillar[5]arene with different fluorescent indicators;

[0027] Figure 3 is the fluorescence situation of different concentrations of the pyridine group-functionalized pillar[5]arene bound with sodium fluorescein under the excitation wavelength of 490 nm;

[0028] Figure 4 Concentration-fluorescence intensity curves of pyridine group-functionalized pillar[5]arenes with different concentrations after binding with sodium fluorescein at an emission wavelength of 515 nm;

[0029] Figure 5 Chemical structures of different modified pillar[5]arenes;

[0030] Figure 6 Binding constants of different modified pillar[5]arenes with sodium fluorescein;

[0031] Figure 7 Binding constants of different modified pillar[5]arenes with PFOA;

[0032] Figure 8 Binding constants of different modified pillar[5]arenes with PFOS;

[0033] Figure 9 Fluorescence intensity of pyridine group-functionalized pillar[5]arene-sodium fluorescein binding PFOA at an excitation wavelength of 490 nm;

[0034] Figure 10 Fluorescence intensity of pyridine group-functionalized pillar[5]arene-sodium fluorescein binding PFOS at an excitation wavelength of 490 nm;

[0035] Figure 11 Fluorescence intensity of pyridine group-functionalized pillar[5]arene-sodium fluorescein binding PFOA at an emission wavelength of 515 nm;

[0036] Figure 12 Fluorescence intensity of pyridine group-functionalized pillar[5]arene-sodium fluorescein binding PFOS at an emission wavelength of 515 nm;

[0037] Figure 13 Test situation of the anti-interference ability of pyridine group-functionalized pillar[5]arene-sodium fluorescein;

[0038] Figure 14 PFOA concentration-fluorescence intensity standard curve constructed based on pyridine group-functionalized pillar[5]arene-sodium fluorescein;

[0039] Figure 15 PFOS concentration-fluorescence intensity standard curve constructed based on pyridine group-functionalized pillar[5]arene-sodium fluorescein. Specific implementation manners

[0040] The examples given are for better illustration of the present invention, but the content of the present invention is not limited only to the examples given. Therefore, those skilled in the art who make non-essential improvements and adjustments to the implementation manners according to the above-mentioned invention content still fall within the protection scope of the present invention.

[0041] The terms used in this document are only for describing specific embodiments and are not intended to limit the present disclosure. Unless having an obviously different meaning in the context, expressions in the singular form include those in the plural form. As used herein, it should be understood that terms such as "including", "having", "containing" are intended to indicate the existence of features, numbers, operations, components, parts, elements, materials or combinations. Terms of the present invention are disclosed in the specification, and are not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials or their combinations may exist or can be added. As used herein, depending on the circumstances, " / " can be interpreted as "and" or "or".

[0042] An embodiment of the present invention provides a pyridine group-functionalized pillar[5]arene or its salt. The structural formula of the pyridine group-functionalized pillar[5]arene is shown as follows:

[0043]

[0044] It should be noted that the pyridine group-functionalized pillar[5]arene can form a salt form to improve water solubility and stability, and the salt form is well known in the art. For example, the nitrogen atom in the pyridine group has a lone pair of electrons and can react with strong acids (such as sulfuric acid, hydrochloric acid) to form a protonated salt; for another example, the pyridine group can also react with halogenated hydrocarbons (such as bromoalkanes) to generate a quaternary ammonium salt (such as bromide salt (Br-)) through nucleophilic substitution; for another example, the pyridine group can combine with Lewis acids (such as silver trifluoromethanesulfonate, aluminum chloride) to form a coordination salt.

[0045] It should also be noted that the structural formula of the pyridine group-functionalized pillar[5]arene in the present invention can be the following structural formula:

[0046] An embodiment of the present invention also provides a preparation method of the pyridine group-functionalized pillar[5]arene in the present invention, including: (1) 1,4-bis(2-bromobutoxy)benzene, an aldehyde group condensation reagent and a Lewis acid catalyst are mixed and reacted to obtain bromobutoxy-modified pillar[5]arene; (2) the bromobutoxy-modified pillar[5]arene and pyridine are mixed and reacted to obtain the pyridine group-functionalized pillar[5]arene.

[0047] It should be noted that in the above preparation method, the aldehyde group condensation reagent refers to a class of compounds containing an aldehyde group (-CHO), which form a bridging structure (such as a methylene bridge) with the benzene ring monomer through a condensation reaction under the catalysis of a Lewis acid, including formaldehyde donors (such as paraformaldehyde) and other aldehyde compounds (such as acetaldehyde, benzaldehyde); it can be selected from formaldehyde donors, C1-C6 aliphatic aldehydes or aromatic aldehydes, and is used to form a bridging structure between benzene ring monomers through a condensation reaction; among them, the formaldehyde donor includes paraformaldehyde, trioxane or formalin, etc. In addition, the Lewis acid catalyst can be selected from boron trifluoride diethyl ether.

[0048] It should also be noted that the structural formulas of 1,4-bis(2-bromobutoxy)benzene and bromobutoxy-modified pillar[5]arene are shown as follows: Among them, 1,4-bis(2-bromobutoxy)benzene can be commercially available or prepared by oneself.

[0049] In some specific examples, the synthesis route of the pyridine group-functionalized pillar[5]arene in the present invention can be shown as follows:

[0050]

[0051] The embodiment of the present invention also provides a fluorescent probe, which includes sodium fluorescein and the pyridine group-functionalized pillar[5]arene or its salt in the present invention, and sodium fluorescein is in the cavity of the pyridine group-functionalized pillar[5]arene or its salt.

[0052] It should be noted that the pyridine group-functionalized pillar[5]arene or its salt in the present invention has a cavity structure, and sodium fluorescein (with fluorescence characteristics) is wrapped in the cavity of the pyridine group-functionalized pillar[5]arene or its salt, and the fluorescence of sodium fluorescein is quenched; when there is other substance that can bind to the pyridine group-functionalized pillar[5]arene or its salt and has a stronger binding ability than sodium fluorescein, sodium fluorescein is displaced and its fluorescence characteristics are restored, and the substance that binds to the pyridine group-functionalized pillar[5]arene or its salt can be qualitatively or quantitatively detected by detecting the fluorescence.

[0053] In some specific examples, in the above fluorescent probe, the molar concentration ratio of sodium fluorescein to the pyridine group-functionalized pillar[5]arene is (0.7-0.9):1, such as 0.75:1, 0.8:1 or 0.85:1.

[0054] The embodiment of the present invention also provides a preparation method of the fluorescent probe in the present invention, including: mixing an aqueous solution of sodium fluorescein and a solution of the pyridine group-functionalized pillar[5]arene to obtain the fluorescent probe.

[0055] It should be noted that in the present invention, the pyridine group-functionalized pillar[5]arene solution can select HEPES buffer solution, and the concentration of the HEPES buffer solution is 10 mM and the pH is 7.4.

[0056] The embodiment of the present invention also provides a detection reagent or kit, which includes the fluorescent probe in the present invention.

[0057] It should be noted that as described above, the fluorescence characteristics in the present invention can qualitatively or quantitatively detect substances that bind to pyridine group-functionalized pillar[5]arene or its salt. Therefore, the fluorescent probe can be prepared in the form of a detection reagent or kit. The detection reagent or kit can include some auxiliary reagents, such as buffer solution; the form of the kit is well known in the art.

[0058] The embodiment of the present invention also provides an application of the fluorescent probe in the present invention in detecting a compound, and the binding constant of the compound with pyridine group-functionalized pillar[5]arene > the binding constant of sodium fluorescein and pyridine group-functionalized pillar[5]arene.

[0059] It should be noted that as described above, the fluorescence characteristics in the present invention can qualitatively or quantitatively detect substances that bind to pyridine group-functionalized pillar[5]arene or its salt. At the same time, the binding ability of the substance binding to it should be stronger than that of sodium fluorescein to displace sodium fluorescein from the cavity structure of pyridine group-functionalized pillar[5]arene or its salt, restore the fluorescence characteristics, and achieve quantitative or qualitative detection.

[0060] In some specific examples, in the above application, the compound is a perfluoro and polyfluoroalkyl compound, especially perfluorooctanoic acid (PFOA) and / or perfluorooctane sulfonate (PFOS).

[0061] It should be noted that when the fluorescent probe in the present invention contacts the compound to be detected, the pyridine group-functionalized pillar[5]arene can specifically recognize and form host-guest complex with PFOA and PFOS molecules, and the process is extremely rapid; moreover, the binding constant between the pyridine group-functionalized pillar[5]arene and PFOA and PFOS is also relatively high, and it can still show good selectivity for PFOA and PFOS even in the presence of various interfering substances, ensuring the accuracy of the detection result.

[0062] The embodiment of the present invention also provides a method for detecting perfluoro and polyfluoroalkyl compounds in water, which includes: (1) constructing a concentration-fluorescence intensity standard curve by using a perfluoro and polyfluoroalkyl compound standard solution with a known concentration and the fluorescent probe in the present invention; detecting the fluorescence intensity of the water body to be detected by using the fluorescent probe; (2) calculating the concentration of perfluoro and polyfluoroalkyl compounds in the water body according to the fluorescence intensity and the concentration-fluorescence intensity standard curve.

[0063] In some specific examples, in the above applications, the perfluoro and polyfluoroalkyl compounds can be perfluorooctanoic acid (PFOA) and / or perfluorooctane sulfonic acid (PFOS).

[0064] It should be noted that, as described above, the pyridyl group-functionalized pillar[5]arene also has a high binding constant with PFOA and PFOS, and can still show good selectivity for PFOA and PFOS even in the presence of various interfering substances, ensuring the accuracy of the detection results; therefore, the fluorescence characteristics in the present invention can accurately detect the concentrations of PFOA and PFOS in water bodies and will not be interfered by other general substances in the water bodies.

[0065] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with specific examples, but the content of the present invention is not limited to the following examples only.

[0066] I. Preparation of Pillar[5]arene

[0067] Example 1

[0068] (1) Add 1,4-dibromobutane (21.59 g, 100 mmol), hydroquinone (2.75 g, 25 mmol), potassium carbonate (20.73 g, 150 mmol) and potassium iodide (1.33 g, 8 mmol) to 200 mL of acetone solution in a 250 mL round-bottom flask, reflux and react at 65 °C, and detect the reaction progress by thin-layer chromatography; after the reactants are completely reacted, quickly add cold water, and a large amount of white precipitate is generated while the reaction is quenched; collect the precipitate and purify it by column chromatography (the eluent uses an ethyl acetate / petroleum ether mixed system (in the mixed system, the volume ratio of ethyl acetate to petroleum ether is 1:5)); after purification, use rotary evaporation to evaporate the solvent to obtain white crystalline 1,4-bis(2-bromobutoxy)benzene (6.2 g, yield 65%).

[0069] (2) In a 250 mL round-bottom flask, dissolve 1,4-bis(2-bromobutoxy)benzene (1.9 g, 5 mmol) in 100 mL of 1,2-dichloroethane, add paraformaldehyde (0.4504 g, 15 mmol) to the solution, and dropwise add 1.5 mL of boron trifluoride etherate under nitrogen protection and react for about 1 h; after the solution reacts to gray-green, add 50 mL of deionized water to quench the reaction; let it stand for layering, collect the organic phase after layering, add anhydrous sodium sulfate for drying, filter and then purify by column chromatography, and the eluent uses a dichloromethane / petroleum ether (the volume ratio of dichloromethane to petroleum ether is 1:1) system to obtain white powdery bromobutoxy-modified pillar[5]arene (0.82 g, yield 38%).

[0070] (3) In a 10 mL round-bottom flask, take bromobutoxy-modified pillar[5]arene (0.5 g, 0.23 mmol) and dissolve it in 3 mL of pyridine solution. Reflux the reaction at 100 °C for 24 h to obtain the reaction product; wash the reaction product with 20 mL of dichloromethane, dissolve it in water and filter; collect the filtrate, add 20 mL of acetonitrile, and dry the solvent by rotary evaporation to obtain brown solid pyridyl group-functionalized pillar[5]arene (hereinafter also referred to as P5CB) (0.52 g, yield 83%).

[0071] The results of the nuclear magnetic resonance hydrogen spectrum of the prepared brown solid pyridyl group-functionalized pillar[5]arene are shown as Figure 1 follows: 1 HNMR(400MHz,Deuterium Oxide)δ8.50(tt,J=7.9,1.3Hz,30H),8.02–7.95(m,20H),6.69(s,10H),4.38(s,20H),3.87(t,J=6.0Hz,20H),3.69(s,10H),1.94(s,20H),1.76(s,20H).

[0072] II. Application of pyridyl group-functionalized pillar[5]arene

[0073] In the following examples, the binding constant and binding ratio are calculated using the Benesi-Hildebrand equation. For specific details, please refer to the literature "Salicylimine-based fluorescent chemosensor for magnesium ions in aqueous solution".

[0074] (I) Screening of fluorescent indicators

[0075] Select four common fluorescent indicators, namely sodium fluorescein (FI), sunset yellow (SY), rhodamine B (RhB), and acridine orange G (AO), to verify the fluorescence quenching effect of pyridyl group-functionalized pillar[5]arene on different indicators; the specific verification method is as follows:

[0076] In HEPES buffer (10 mM, pH = 7.4), the concentration of sodium fluorescein was fixed at 1 μM, and then pyridine group-functionalized pillar[5]arene with different concentrations (0, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, and 1 μM) was added to obtain different sodium fluorescein fluorescence systems; sodium fluorescein was replaced with sunset yellow, rhodamine B, and acridine orange G respectively, and different sunset yellow fluorescence systems, rhodamine B fluorescence systems, and acridine orange G fluorescence systems were prepared according to the above method; a fluorescence spectrophotometer (Shimadzu RF6000, the same below) was used to measure the fluorescence intensities of different systems at the corresponding excitation wavelengths and emission wavelengths; among them, the excitation wavelength of sodium fluorescein was 490 nm, and the emission wavelength was 515 nm; the excitation wavelength of sunset yellow was 480 nm, and the emission wavelength was 520 nm; the excitation wavelength of rhodamine B was 550 nm, and the emission wavelength was 580 nm; the excitation wavelength of acridine orange G was 490 nm, and the emission wavelength was 530 nm.

[0077] The test results are as Figure 2 shown. The results show that with the increase in the concentration of pyridine group-functionalized pillar[5]arene, only sodium fluorescein produced an obvious fluorescence quenching effect, and the fluorescence intensity decreased significantly; while the fluorescence intensities of sunset yellow, rhodamine B, and acridine orange G remained stable, and there was no decrease in fluorescence intensity. This indicates that there is a binding behavior only between sodium fluorescein and pyridine group-functionalized pillar[5]arene.

[0078] (II) Exploration of the stability of the fluorescent indicator

[0079] In HEPES buffer (10 mM, pH = 7.4, prepared by diluting the purchased HEPES buffer (concentration 0.5 mol / L, pH = 7.4) with deionized water, the same below), the concentration of sodium fluorescein was fixed at 1 μM, and then pyridine group-functionalized pillar[5]arene with different concentrations (0, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.3 μM, 2 μM, 3 μM, 4 μM, 5 μM, 7 μM, 9 μM, 11 μM, and 15 μM) was added to obtain different systems, and the binding constant and binding ratio between pyridine group-functionalized pillar[5]arene and sodium fluorescein were measured according to the above reference test method. The results are as Figure 3 shown. The results show that with the addition of pyridine group-functionalized pillar[5]arene, sodium fluorescein was encapsulated in the large cavity of pyridine group-functionalized pillar[5]arene, and the fluorescence intensity of the system gradually decreased at the excitation wavelength of 490 nm.

[0080] In addition, pyridine group-functionalized pillar[5]arenes with different concentrations (0, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.3 μM, 2 μM, 3 μM, 4 μM, 5 μM, 7 μM, 9 μM, 11 μM, and 15 μM) were used to measure the fluorescence intensity at an emission wavelength of 515 nm, and a concentration-fluorescence intensity curve was plotted. The results are as Figure 4 shown. The results show that the obtained results satisfy a binding mode with a binding ratio of 1:1, and the binding constant reaches 8.60×10 5 M -1 . The relatively high binding constant confirms the stable complexation between the pyridine group-functionalized pillar[5]arene and sodium fluorescein, indicating that the fluorescence probe formed by their combination has high stability.

[0081] (III) Comparison of the binding constants of different modified pillar[5]arenes with sodium fluorescein

[0082] Quaternary ammonium group-modified short-chain pillar[5]arene (P5A), pyridine group-modified short-chain pillar[5]arene (P5B), and quaternary ammonium group-modified long-chain pillar[5]arene (P5CA) were synthesized according to the synthesis methods described in "Photocontrolled Reversible Guest Uptake, Storage, and Release by Azobenzene-Modified Microporous Multilayer Films of Pillar[5]arenes", "A Water-Soluble Leggero Pillar[5]arene", and "Study on the Synthesis of Supramolecular Sensors Based on Quaternized Pillar[5]arenes and Their Host-Guest Recognition Properties". In addition, the pyridine group-functionalized pillar[5]arene (P5CB) in the present invention was used for comparison. The structures of the above different pillar[5]arenes are as Figure 5 shown.

[0083] In HEPES buffer (10 mM, pH = 7.4), the concentration of sodium fluorescein was fixed at 1 μM, and then different concentrations (0, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.3 μM, 2 μM, 3 μM, 4 μM, 5 μM, 7 μM, 9 μM, 11 μM, and 15 μM) of pyridine group-functionalized pillar[5]arene (P5CB) were added to obtain different pillar[5]arene systems; the pyridine group-functionalized pillar[5]arene (P5CB) was replaced with quaternary ammonium group-modified short-chain pillar[5]arene (P5A), pyridine group-modified short-chain pillar[5]arene (P5B), and quaternary ammonium group-modified long-chain pillar[5]arene (P5CA) to obtain different pillar[5]arene systems; the binding constant between the pyridine group-functionalized pillar[5]arene and sodium fluorescein was measured according to the test method in the above reference.

[0084] The results are as Figure 6 shown. The results show that the binding constant of P5A with sodium fluorescein is 2.51×10 5 M -1 , the binding constant of P5B with sodium fluorescein is 2.78×10 5 M -1 , and the binding constant of P5CA with sodium fluorescein is 4.74×10 5 M -1 , all of which are lower than the binding constant of the pyridine group-functionalized calix[5]arene synthesized in the present invention with sodium fluorescein.

[0085] (IV) Comparison of the binding constants of different modified calix[5]arenes with PFOA

[0086] In HEPES buffer (10 mM, pH = 7.4), the concentration of pyridine group-functionalized calix[5]arene (P5CB) was fixed at 0.8 μM, and the concentration of sodium fluorescein was 1 μM. Then, different concentrations (0, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.3 μM, 2 μM, 3 μM, 4 μM, 5 μM, 7 μM, 9 μM, 11 μM, and 15 μM) of PFOA were added to obtain different test systems; the pyridine group-functionalized calix[5]arene (P5CB) was replaced with quaternary ammonium group-modified short-chain calix[5]arene (P5A), pyridine group-modified short-chain calix[5]arene (P5B), and quaternary ammonium group-modified long-chain calix[5]arene (P5CA) to obtain different test systems; the binding constant between the pyridine group-functionalized calix[5]arene and PFOA was measured according to the above reference test method.

[0087] The results are as Figure 7 shown. The results show that the binding constant of P5A with PFOA is 2.36×10 5 M -1 , the binding constant of P5B with PFOA is 2.67×10 5 M -1 , and the binding constant of P5CA with PFOA is 6.38×10 5 M -1 , all of which are lower than the binding constant of the pyridine group-functionalized calix[5]arene synthesized in the present invention with PFOA.

[0088] (V) Comparison of the binding constants of different modified calix[5]arenes with PFOS

[0089] In HEPES buffer (10 mM, pH = 7.4), the concentration of pyridyl group-functionalized pillar[5]arene (P5CB) was fixed at 0.8 μM, and the concentration of sodium fluorescein was 1 μM. Then, different concentrations (0, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 1.3 μM, 2 μM, 3 μM, 4 μM, 5 μM, 7 μM, 9 μM, 11 μM, and 15 μM) of PFOS were added to obtain different test systems; pyridyl group-functionalized pillar[5]arene (P5CB) was replaced with quaternary ammonium group-modified short-chain pillar[5]arene (P5A), pyridyl group-modified short-chain pillar[5]arene (P5B), and quaternary ammonium group-modified long-chain pillar[5]arene (P5CA) to obtain different test systems; according to the test method in the above reference, the binding constant between pyridyl group-functionalized pillar[5]arene and PFOS was measured.

[0090] The results are as Figure 8 shown. The results show that the binding constant between P5A and PFOS is 3.06×10 5 M -1 , the binding constant between P5B and PFOS is 5.04×10 5 M -1 , and the binding constant between P5CA and PFOS is 1.20×10 6 M -1 , all of which are lower than the binding constant between the pyridyl group-functionalized pillar[5]arene synthesized in the present invention and PFOS.

[0091] (VI) Investigation on the host-guest binding properties between the fluorescent probe constructed by pyridyl group-functionalized pillar[5]arene and sodium fluorescein and PFOA and PFOS

[0092] In HEPES buffer (10 mM, pH = 7.4), pyridyl group-functionalized pillar[5]arene and sodium fluorescein were added respectively. Among them, the concentration of pyridyl group-functionalized pillar[5]arene was 0.8 μM, and the concentration of sodium fluorescein was 1 μM. Then, different concentrations (0, 0.2 μM, 0.4 μM, 0.6 μM, 0.8 μM, 1 μM, 2 μM, 3 μM, 6 μM, 8 μM, 10 μM, 13 μM, and 16 μM) of PFOA were added; according to the test method in the above reference, the binding constant and binding ratio between pyridyl group-functionalized pillar[5]arene and PFOA were measured; similarly, according to the above method, the binding constant and binding ratio between pyridyl group-functionalized pillar[5]arene and PFOS were measured.

[0093] Among them, the fluorescence intensities corresponding to different concentrations of PFOA and PFOS systems at the emission wavelength of 515 nm were taken to make a concentration-fluorescence intensity curve. The concentration-fluorescence intensity curves are as Figure 9 and Figure 10As shown, the results show that with the addition of PFOA and PFOS, sodium fluorescein is displaced, and the fluorescence intensity of the system at an excitation wavelength of 490 nm gradually increases.

[0094] In addition, the binding constants and binding ratios are as shown in Figure 11 and Figure 12 The results show that the pyridine group-functionalized pillar[5]arene satisfies a 1:1 binding mode with both PFOA and PFOS. The binding constant with PFOA reaches 8.70×10 5 M -1 and the binding constant with PFOS reaches 1.59×10 6 M -1 proving that there is a high binding force between the pyridine group-functionalized pillar[5]arene and both PFOA and PFOS.

[0095] From the above, it can be known that compared with the other three known functionalized pillar[5]arenes, the pyridine group-functionalized pillar[5]arene synthesized in the present invention not only has higher stability as a fluorescence probe, but also can bind more firmly to PFOA and PFOS molecules during detection, improving the accuracy of the detection results.

[0096] III. Investigation of the anti-interference ability of pyridine group-functionalized pillar[5]arene-sodium fluorescein

[0097] A fluorescence probe was prepared by adding pyridine group-functionalized pillar[5]arene and sodium fluorescein to HEPES buffer (10 mM, pH = 7.4) respectively; among them, the concentration of pyridine group-functionalized pillar[5]arene was 10 μM and the concentration of sodium fluorescein was 1 μM.

[0098] PFOA and PFOS and several common anionic interferents in water bodies (including NaF (F - ), NaCl (Cl - ), NaBr (Br - ), KNO 3 (NO 3 - ), Na 2 SO 4 (SO 4 2- ), Na 2 CO 3 (CO 3 2- ), and KH 2 PO 4 (H 2 PO 4 -)) The concentration of each additive was 50 μM. A fluorescence spectrophotometer (Shimadzu RF6000) was used to test the fluorescence of the fluorescent probe after adding different substances, so as to test the selectivity of the fluorescent probe for PFOA and PFOS.

[0099] The test results are as Figure 13 shown. The results show that the fluorescent probe only shows strong fluorescence expression upon the addition of PFOA and PFOS, indicating that the pyridine group-functionalized pillar[5]arene exhibits high selectivity for PFOA and PFOS, demonstrating that the developed detection method has strong anti-interference ability.

[0100] IV. Application of Pyridine Group-Functionalized Pillar[5]Arene in Water Sample Detection

[0101] (1) Take several 15 mL centrifuge tubes, and add 100 μL of a 0.1 mM fluorescein sodium solution, 5 mL of a 10 mM HEPES buffer solution (pH 7.4), and 80 μL of a 0.1 mM pyridine group-functionalized pillar[5]arene solution to each tube respectively. Vortex for 30 s to prepare a fluorescent probe in which the pyridine group-functionalized pillar[5]arene binds to fluorescein sodium.

[0102] (2) Then take five fluorescent probes, and add 0 μL, 20 μL, 40 μL, 60 μL, and 80 μL of a 0.1 mM PFOA standard solution to them respectively. Use 10 mM HEPES buffer solution to make up the system to 10 mL. At this time, the concentrations of the pyridine group-functionalized pillar[5]arene and fluorescein sodium in the system are 0.8 μM and 1 μM respectively, and the concentrations of PFOA are 0 μM, 0.2 μM, 0.4 μM, 0.6 μM, and 0.8 μM respectively. After vortexing for 1 min, use a fluorescence spectrophotometer (Shimadzu RF6000) to measure the fluorescence intensity of the liquid in each centrifuge tube at an excitation wavelength of 490 nm and an emission wavelength of 515 nm, and draw a standard curve of PFOA concentration-fluorescence intensity, as Figure 14 shown. In addition, draw a standard curve of PFOS concentration-fluorescence intensity in the same way as above, and the results are as Figure 15 shown.

[0103] (3) Prepare the water samples to be detected: Take tap water and add different amounts of PFOA to prepare water samples to be detected containing different concentrations of PFOA (see Table 1); take tap water and add different amounts of PFOS to prepare water samples to be detected containing different concentrations of PFOS (see Table 2).

[0104] (4) Take several fluorescent probes, add them to 200 μL of the above-mentioned water sample to be tested respectively, then supplement the system to 10 mL with 10 mM HEPES buffer solution. After vortexing for 1 min, use a fluorescence spectrophotometer (Shimadzu RF6000) to measure the fluorescence intensity of the liquid in each centrifuge tube at an excitation wavelength of 490 nm and an emission wavelength of 515 nm, and compare it with the concentration-fluorescence intensity standard curve to obtain the specific concentration of the corresponding perfluoro and polyfluoroalkyl compounds.

[0105] Among them, the test results of the water sample to be tested containing PFOA are shown in Table 1 below.

[0106] Table 1 Test Results of Water Sample to be Tested for PFOA

[0107] Sample number PFOA water sample concentration (μM) PFOA test concentration (μM) Relative error 1 0.200 0.209 4.5％ 2 0.400 0.406 1.5％ 3 0.600 0.584 2.6％

[0108] As can be seen from Table 1 above, the error between the test value of PFOA in the water sample detected by the fluorescent probe in the present invention and the actual value of PFOA in the water sample is small, indicating that the detection accuracy is relatively high.

[0109] In addition, the test results of the water sample to be tested containing PFOS are shown in Table 2 below.

[0110] Table 2 Test Results of Water Sample to be Tested for PFOS

[0111]

[0112]

[0113] As can be seen from Table 2 above, the error between the test value of PFOS in the water sample detected by the fluorescent probe in the present invention and the actual value of PFOS in the water sample is small, indicating that the detection accuracy is relatively high.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. Pyridine group functionalized column [5] aromatic hydrocarbon or its salt, the structural formula of pyridine group functionalized column [5] aromatic hydrocarbon is as follows:

2. The method for preparing the pyridine group functionalized pillar [5] aromatic hydrocarbon according to claim 1, characterized in that: include: (1) 1,4-bis(2-bromobutyloxy)benzene, an aldehyde condensation reagent and a Lewis acid catalyst are mixed to obtain bromobutyloxy-modified pillar[5]arene; (2) The bromobutoxy-modified pillar[5]arene and pyridine are mixed to obtain pyridine-functionalized pillar[5]arene.

3. A fluorescent probe, characterized in that It comprises sodium fluorescein and the pyridine group functionalized column [5] aromatic hydrocarbon or its salt as claimed in claim 1, wherein the sodium fluorescein is in the cavity of the pyridine group functionalized column [5] aromatic hydrocarbon or its salt.

4. The fluorescent probe according to claim 3, characterized in that The molar concentration ratio of fluorescein sodium and pyridine group functionalized column [5] aromatic hydrocarbon is (0.7-0.9):

1.

5. The method for preparing the fluorescent probe according to claim 3 or 4, characterized in that: include: The fluorescent probe is obtained by mixing a sodium fluorescein aqueous solution and a pyridine group functionalized column [5] aromatic hydrocarbon solution.

6. A detection reagent or a kit, characterized in that: Includes the fluorescent probe described in claim 3 or 4.

7. Use of the fluorescent probe according to claim 3 or 4 in detecting a compound, wherein the binding constant of the compound to the pyridine group functionalized column [5] aromatic hydrocarbon is greater than the binding constant of sodium fluorescein to the pyridine group functionalized column [5] aromatic hydrocarbon.

8. The use according to claim 7, characterized in that: The compounds are perfluoro and polyfluoroalkyl compounds.

9. The use according to claim 8, characterized in that: The perfluoro and polyfluoroalkyl compounds are selected from perfluorooctanoic acid and / or perfluorooctane sulfonic acid.

10. A method for detecting perfluoroalkyl and polyfluoroalkyl compounds in water, characterized in that: include: (1) constructing a concentration-fluorescence intensity standard curve using a known concentration of a perfluoroalkyl and polyfluoroalkyl compound standard solution and the fluorescent probe described in claim 3 or 4; and using the fluorescent probe to detect the fluorescence intensity of the water body to be detected; (2) The concentration of perfluoroalkyl compounds and polyfluoroalkyl compounds in water is calculated based on the fluorescence intensity and the concentration-fluorescence intensity standard curve.

Images