Ligand compounds, rare earth supramolecular sensor materials, sensor thin films, fluorescent probes, and preparation methods and uses

Abstract

To provide a ligand compound which is used for detecting a content of heavy metal ions in water environment, and enables formation of rare earth metal ions and a rare earth supermolecular sensor material for achieving microanalysis of cadmium ions at a particularly low detection limit, and a preparation method, and to provide a rare earth supermolecular sensor material, a sensor thin film, a fluorescent probe and a preparation method, and use.SOLUTION: A ligand compound has a structure represented by formula (I).SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a ligand compound, a rare earth supramolecular sensor material, a sensor thin film, a fluorescent probe and a method for preparing and using the same. [Background technology]

[0002] Heavy metals include gold, silver, copper, iron, mercury, lead, cadmium, etc. From the perspective of environmental pollution, heavy metals primarily refer to highly biotoxic heavy elements such as mercury, cadmium, lead, chromium, and the metalloid arsenic. Because heavy metals are difficult to biodegrade, they become concentrated thousands of times through biological enrichment in the food chain and ultimately enter the human body. Heavy metals can strongly interact with proteins and enzymes in the human body, deactivating them, or accumulate in certain organs, causing chronic poisoning.

[0003] Cadmium is a highly toxic heavy metal, and most of its compounds are toxic. Industrial wastewater containing cadmium contaminates rivers and farmland. Cadmium is more easily absorbed by crops, vegetables, and rice than other heavy metals. When contaminated crops are eaten, cadmium enters the human body through the digestive tract and accumulates primarily in the liver and kidneys, causing damage. Long-term cadmium intake affects the function of hematopoiesis, nerves, kidneys, and other organs, causing significant damage to human health, especially children. Cadmium is highly destructive to the central nervous system, and once cadmium enters the body, it is extremely difficult to excrete, severely disrupting kidney and reproductive function. Cadmium displaces calcium in bones, causing severe bone softening and fragmentation. Cadmium can also cause gastric dysfunction, reduce the zinc-to-cadmium ratio, and increase high blood pressure. "Itai-itai disease" is a typical example of chronic cadmium poisoning, caused by cadmium contamination of the human living environment, has widespread effects, and has claimed many lives, so it has been recognized as a "pollution disease."

[0004] Cadmium contamination is also characterized by a long cycle and high degree of concealment. Cadmium is potentially toxic and can accumulate in human tissues (especially women) even at low cadmium concentrations of 0.1 mg / L in drinking water. The incubation period is as long as 10 to 30 years, making it difficult to detect medical symptoms in the early stages.

[0005] Currently, traditional methods such as atomic absorption spectrometry, atomic fluorescence spectrometry, and inductively coupled plasma spectrometry are mature and capable of meeting the needs for accuracy and precision, but they are limited to scientific research institutions because they require time-consuming detection, special sample processing to reduce noise interference, and large laboratory equipment.

[0006] Crown ethers are a type of cyclic compound composed of polyether units, and have strong metal complexing properties, making them useful as metal ion trapping agents. CN110394166A discloses a crown ether-type lignin-based adsorbent produced using an amino crown ether compound and lignin as raw materials via the Mannich reaction, and a method for producing the adsorbent. The adsorbent is used in fields such as the treatment of wastewater containing ions of heavy metals such as mercury, lead, and copper, and the purification of water resources.

[0007] Researchers have been interested in how to capture heavy metal ions and identify them through changes in luminescence signal or fluorescence intensity, thereby achieving qualitative or quantitative trace detection and analysis of heavy metal ions. CN109897317A discloses a cellulose nanocrystal-rare earth complex-polyvinyl alcohol composite hydrogel fluorescent probe, which constructs a rare earth europium complex in a reversibly crosslinked hydrogel, enabling the detection of heavy metal ions in aqueous environments. This patent document describes the use of a cellulose nanocrystal / polyvinyl alcohol composite gel to improve the mechanical properties of the fluorescent probe, enabling the detection of heavy metal ions. Summary of the Invention

[0008] One object of the present invention is to provide a ligand compound capable of forming a rare earth supramolecular sensor material with a rare earth metal ion, which can be used to detect the content of heavy metal ions in an aqueous environment, particularly for the trace analysis of cadmium ions with a low detection limit. Another object of the present invention is to provide a method for preparing the ligand compound. Another object of the present invention is to provide a rare earth supramolecular sensor material capable of detecting the content of heavy metal ions, particularly cadmium ions, in an aqueous environment with high sensitivity, a low detection limit, and good reproducibility. Another object of the present invention is to provide a method for preparing the rare earth supramolecular sensor material. Another object of the present invention is to provide uses of the rare earth supramolecular sensor material. Other objects of the present invention include providing a sensor thin film and a fluorescent probe.

[0009] In one aspect, the present invention provides a ligand compound having a structure shown in formula (I):

[0010] TIFF0007792471000001.tif64170(In formula (I), R 1 is trihalomethyl, and R 2 is selected from the structures represented by the following formula (II):

[0011] TIFF0007792471000002.tif29170 (In formula (II), X is at least one selected from oxygen and sulfur, and always contains oxygen.)

[0012] The ligand compound according to the present invention preferably has a structure represented by the following formula:

[0013] TIFF0007792471000003.tif62170

[0014] In another aspect, the present invention provides a method for producing a medicament for the treatment of a pulmonary arthritis, comprising: Step (1) of subjecting a compound represented by formula (1c) to a bromine substitution reaction to obtain a compound represented by formula (1d); Compounds represented by formula (1d) and HR 2Step (2) of reacting the compound represented by formula (1e) with a raw material to obtain the compound represented by formula (1e); and Step (3) of reacting the compound represented by formula (1e) with the compound represented by formula (IV) to obtain the ligand compound; The present invention provides a method for preparing the ligand compound, comprising:

[0015] TIFF0007792471000004.tif95170 (in formula (1e), R 2 is selected from the structures represented by the following formula (II): TIFF0007792471000005.tif35170 (In formula (II), X is at least one selected from oxygen and sulfur, and always contains oxygen.) TIFF0007792471000006.tif23170 (in formula (IV), R 1 is trihalomethyl.

[0016] According to the preparation method of the present invention, preferably In step (1), a compound represented by formula (1c) is reacted with N-bromosuccinimide to obtain a compound represented by formula (1d); In step (2), a compound represented by formula (1d) and HR 2 and a compound represented by formula (1e) in the presence of cesium carbonate, In step (3), first, the compound represented by formula (IV) is reacted with sodium methoxide, and then the compound represented by formula (1e) is added and reacted to obtain the ligand compound.

[0017] According to the preparation method of the present invention, preferably (i) reacting m-halotoluene with an acetyl halide to form a compound of formula (1a); (ii) reacting m-acetotoluidine with an acetyl halide to form a compound of formula (1b); and (iii) a step of reacting a compound represented by formula (1a) with a compound represented by formula (1b) to obtain a compound represented by formula (1c); further comprising Among these, steps (i) and (ii) may be performed in any order.

[0018] TIFF0007792471000007.tif24170 (In formula (1a), Y is bromine or iodine.) TIFF0007792471000008.tif25170

[0019] In another aspect, the present invention provides a method for preparing a rare earth metal ion RE complex comprising the above-described ligand compound and the rare earth metal ion RE complex. 3+ A rare earth supramolecular sensor material formed from rare earth metal ions RE 3+ is Sm 3+ ,EU 3+ , Tb 3+ , Er 3+ and Lu 3+ The present invention further provides a rare earth supramolecular sensor material, which is at least one selected from:

[0020] In another aspect, the present invention further provides a method for preparing the rare earth supramolecular sensor material, comprising the steps of dissolving the ligand compound in a C1-C3 alkyl alcohol and reacting it with a rare earth chloride in the presence of an alkaline substance to obtain the rare earth supramolecular sensor material, wherein the alkaline substance is selected from triethylamine or pyridine.

[0021] In another aspect, the present invention further provides the use of said rare earth supramolecular sensor material in detecting heavy metal ion content in an aqueous environment, wherein said heavy metal ions comprise cadmium ions.

[0022] In another aspect, the present invention provides a sensor thin film having a thickness of less than 100 nm, formed by applying the rare earth supramolecular sensor material to a substrate.

[0023] Finally, the present invention further provides a fluorescent probe comprising the sensor thin film.

[0024] The present invention utilizes a triphenylamine-based tri-β-diketone ligand to coordinate with rare earth metal ions (especially europium ions) to achieve fluorescent responses of the rare earth metal ions. Furthermore, the introduction of an azacrown ether as a heavy metal ion recognition group at the meta position of the amine group in the triphenylamine skeleton allows for the capture of heavy metal ions, particularly cadmium ions. The coordination of the nitrogen on the benzene ring with the ligand affects energy transfer from the ligand to the rare earth metal ion (especially europium ions), resulting in enhanced fluorescence in the rare earth supramolecular sensor material of the present invention. The rare earth supramolecular sensor material of the present invention can be used to analyze trace amounts of heavy metal ions (especially cadmium ions) in water, with improved analytical efficiency, sensitivity, and reproducibility, and a low detection limit. The reaction conditions for the preparation method of the present invention are mild and safe. The purity of the resulting ligand compound and rare earth supramolecular sensor material can reach 99.0% or more. The present invention further enables the fabrication of nanoscale sensor thin films (thickness <100 nm) by spin-coating rare earth supramolecular sensor materials onto quartz chips, and the voids between the thin films can be used to create reversible fluorescent probes that can be used multiple times, thereby enabling the analysis of trace cadmium ion content, improving efficiency and reducing costs. [Brief explanation of the drawings]

[0025] [Figure 1] 1 shows the ultraviolet absorption spectra of the rare earth supramolecular sensor material prepared in Example 2 of the present invention capturing different concentrations of cadmium ions. [Figure 2] 4 shows the fluorescence spectra of different concentrations of cadmium ions captured by the rare earth supramolecular sensor material prepared in Example 2 of the present invention. [Figure 3] 4 shows the fluorescence intensity spectra at 616 nm under ultraviolet excitation wavelength of the rare earth supramolecular sensor material prepared in Example 2 of the present invention after the concentration of different metal ions is enhanced by 10 times. [Figure 4] 1 is a hydrogen spectrum of the intermediate 1e compound obtained in Example 1 of the present invention. [Figure 5]1 is a hydrogen spectrum of the ligand compound obtained in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will now be further described with reference to specific examples, which do not limit the scope of the claims.

[0027] <Terminology> In the present invention, Cm-Cn means having m to n carbon atoms, for example, a C1-C3 alkyl group means an alkyl group having 1 to 3 carbon atoms.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned in this application are incorporated by reference in their entirety. In the case of conflict, the present specification and definitions contained therein will control. Additionally, the materials, methods, preparations, and examples are illustrative only and are not intended to be limiting.

[0029] <Ligand compound> The ligand compound of the present invention can form a rare earth supramolecular sensor material with rare earth metal ions, and the formed rare earth supramolecular sensor material can be used to capture heavy metal ions, especially cadmium ions, in water, which can be used for trace analysis of heavy metal ions in aqueous environments, and the content of heavy metal ions can be determined by the fluorescence response value.

[0030] The ligand compound according to the present invention has a structure represented by formula (I).

[0031] TIFF0007792471000009.tif64170(In formula (I), R 1is trihalomethyl, for example, trifluoromethyl, trichloromethyl or tribromomethyl, preferably trifluoromethyl. R 2 is selected from the structures represented by the following formula (II):

[0032] TIFF0007792471000010.tif30170 (In formula (II), X is at least one selected from oxygen and sulfur, and always contains oxygen.)

[0033] In some embodiments, all X are oxygen. In other embodiments, some X are oxygen and some X are sulfur.

[0034] According to one embodiment of the present invention, R in the structure of formula (I) 1 is trifluoromethyl, and in formula (II), all X's are oxygen, and the ligand compound according to the present invention has the structure shown below.

[0035] TIFF0007792471000011.tif62170

[0036] As a result of extensive research, the inventors have found that a tri-β-diketone with a triphenylamine skeleton serves as a ligand, and by coordinating with rare earth metal ions (especially europium ions), the fluorescent response of the rare earth metal ions can be realized. Furthermore, by introducing an azacrown ether as a heavy metal ion recognition group at the meta-position of the amine group of the triphenylamine skeleton, heavy metal ions, particularly cadmium ions, can be captured. When the nitrogen on the benzene ring coordinates with the ligand, it affects the energy transfer from the ligand to the rare earth ion, resulting in a fluorescence enhancement phenomenon in the rare earth supramolecular sensor material.

[0037] After introducing an azacrown ether as a heavy metal ion recognition group into the meta position of the amine group in the triphenylamine skeleton synthesized in this invention, the resulting rare earth supramolecular sensor material exhibits a fluorescent response to heavy metal ions, particularly cadmium ions. When the concentration of the captured heavy metal ions (especially cadmium ions) reaches a certain level, fluorescence decay or quenching occurs. Such rare earth supramolecular sensor materials produce fluorescence of different intensities when samples with different ion concentrations are tested, which can be detected using a fluorometer.

[0038] <Method for preparing ligand compounds> The present invention further provides a method for preparing the ligand compound, which includes step (1) of synthesizing a compound represented by formula (1d), step (2) of synthesizing a compound represented by formula (1e), and step (3) of synthesizing a ligand compound. Optionally, the method further includes step (i) of synthesizing a compound represented by formula (1a), step (ii) of synthesizing a compound represented by formula (1b), and step (iii) of synthesizing a compound represented by formula (1c). The order of steps (i) and (ii) can be arbitrary. The method is described in detail below.

[0039] Synthesis of the compound represented by formula (1a) That is, this is the synthesis process of intermediate 1a. m-Halotoluene and acetyl halide are reacted to form the compound represented by formula (1a).

[0040] TIFF0007792471000012.tif24170 (In formula (1a), Y is bromine or iodine.)

[0041] The m-halotoluene may be m-chlorotoluene, m-bromotoluene, or m-iodotoluene, preferably m-iodotoluene. The acetyl halide may be acetyl chloride or acetyl bromide, preferably acetyl chloride.

[0042] According to one embodiment of the present invention, m-halotoluene is dissolved in 1,2-dichloroethane as a solvent to form a first solution, acetyl halide and anhydrous aluminum trichloride are added to 1,2-dichloroethane as a solvent to form a second solution, the second solution is added to the first solution, and the reaction is carried out in an ice bath. After the reaction is completed, the reaction system is quenched by placing it in ice water, and the liquids are separated by standing. The organic layer is collected, and the aqueous layer is extracted with dichloromethane or chloroform. The organic phases are combined. The combined organic phases are washed with water until neutral, and then dried and concentrated to obtain a concentrate. The concentrate is then subjected to column chromatography (eluent for column chromatography: petroleum ether / ethyl acetate) to obtain the compound represented by formula (1a) as an oily liquid.

[0043] The molar ratio of m-halotoluene to acetyl halide may be 1:1.9-2.1, preferably 1:2.0-2.02. The molar ratio of m-halotoluene to anhydrous aluminum trichloride may be 1:1.9-2.1, preferably 1:2.0-2.03.

[0044] According to one embodiment of the present invention, the m-halotoluene is m-iodotoluene, the acetyl halide is acetyl chloride, and the reaction scheme is as follows:

[0045] TIFF0007792471000013.tif27170

[0046] Synthesis of the compound represented by formula (1b) That is, this is the synthesis process of intermediate 1b. m-Acetotoluidine and acetyl halide are reacted to form the compound represented by formula (1b).

[0047] TIFF0007792471000014.tif25170 The acetyl halide may be acetyl chloride or acetyl bromide, and is preferably acetyl chloride.

[0048] According to one embodiment of the present invention, m-acetotoluidine is dissolved in 1,2-dichloroethane as a solvent to obtain a third solution, and acetyl halide and anhydrous aluminum trichloride are dissolved in 1,2-dichloroethane as a solvent to obtain a fourth solution. The fourth solution is added to the third solution in batches and reacted under heating and reflux. After the reaction is complete, the reaction system is quenched by placing it in ice water, and dilute hydrochloric acid is added to adjust the pH to 2-3 and stirred at room temperature for 1-1.5 hours. The pH is then adjusted to a weak base, and the mixture is allowed to stand for liquid separation. The organic layer is collected, and the aqueous layer is extracted with dichloromethane or chloroform. The organic phases are combined, dried, and concentrated to obtain a concentrate. The concentrate is then subjected to column chromatography (eluent: petroleum ether / ethyl acetate) to obtain an oily liquid. This gives the compound represented by formula (1b).

[0049] The molar ratio of m-acetotoluidine to acetyl halide is 1:2.2 to 2.6, preferably 1:2.4 to 2.55. The molar ratio of acetyl halide to anhydrous aluminum trichloride is 1:1.

[0050] According to one particular embodiment of the present invention, the specific reaction scheme is as follows:

[0051] TIFF0007792471000015.tif29170

[0052] Synthesis process of the compound represented by formula (1c) That is, this is a synthesis process for intermediate 1c. A compound represented by formula (1a) is reacted with a compound represented by formula (1b) to obtain a compound represented by formula (1c).

[0053] TIFF0007792471000016.tif39170

[0054] In this process, the solvent is 1,2-o-dichlorobenzene, and the reaction aids are copper powder, 18-crown-6, and potassium carbonate, among which copper powder is the catalyst, 18-crown-6 is the phase transfer catalyst, and potassium carbonate is the alkali agent.

[0055] In some embodiments, intermediates 1a and 1b are dissolved in 1,2-o-dichlorobenzene under inert gas protection, and copper powder, 18-crown-6, and potassium carbonate are added to the solution. The reaction is allowed to proceed under reflux for 18 to 32 hours. After the reaction is complete, the solid is removed by solid-liquid separation. The mother liquor is washed with ammonia and then with water, and the organic layer is extracted. The organic layer is dried and concentrated to obtain a concentrate, which is then separated by column chromatography (eluent: petroleum ether / ethyl acetate, volume ratio of the two = 5:1) to obtain a solid. This yields the compound represented by formula (1c).

[0056] The molar ratio of intermediate 1a to intermediate 1b may be 2.1 to 2.6:1, preferably 2.4 to 2.6:1, and more preferably 2.5 to 2.55:1.

[0057] The molar ratio of copper powder to intermediate 1b may be 8 to 11:1, preferably 9.5 to 10.5:1, and more preferably 9.9 to 10.1:1. The molar ratio of 18-crown-6 to intermediate 1b may be 0.05 to 0.07:1, and preferably 0.06 to 0.07:1. The molar ratio of potassium carbonate to intermediate 1b may be 1.4 to 1.6:1, preferably 1.48 to 1.55:1, and more preferably 1.49 to 1.51:1.

[0058] Synthesis of the compound represented by formula (1d) That is, this is the synthesis process of intermediate 1d. A compound represented by formula (1c) is subjected to a bromine substitution reaction to obtain a compound represented by formula (1d).

[0059] TIFF0007792471000017.tif45170

[0060] In the present invention, the reagent used for bromine substitution is NBS (N-bromosuccinimide).

[0061] In some embodiments, intermediate 1c is dissolved in acetonitrile to obtain an acetonitrile solution, NBS is added to the acetonitrile solution in batches, and the mixture is allowed to react at room temperature for 18-36 hours with continued stirring. After the reaction is complete, the mixture is reduced with sodium thiosulfate and extracted multiple times with ethyl acetate. The organic layers are collected, dried, filtered, and concentrated, and the concentrate is recrystallized to obtain a solid, i.e., a compound of formula (1d).

[0062] The molar ratio of intermediate 1c to NBS may be 1:3.1 to 3.5, preferably 1:3.2 to 3.4, and more preferably 1:3.3 to 3.35. The solvent used for recrystallization is ethanol.

[0063] Synthesis process of the compound represented by formula (1e) That is, this is the synthesis process of intermediate 1e. 2 Specifically, the compound represented by formula (1d) is reacted with HR 2 is reacted in the presence of cesium carbonate to obtain the compound represented by formula (1e).

[0064] TIFF0007792471000018.tif45170H-R 2 The structural formula is as follows:

[0065] TIFF0007792471000019.tif28170 (wherein X is at least one selected from oxygen and sulfur, and always contains oxygen.)

[0066] In some embodiments, HR in anhydrous acetone 2A mixture of the raw material and cesium carbonate is heated under reflux under the protection of an inert gas for 1 to 1.5 hours to react, and then the compound represented by formula (1d) is added to the reaction system and allowed to react for 24 to 38 hours under reflux. After the reaction is complete, the temperature is lowered, and the reaction liquid is quenched by pouring it into ice water. A solid crude product is obtained by solid-liquid separation, and the solid crude product is separated by column chromatography (petroleum ether / ethyl acetate, volume ratio of the two = 1:3) to obtain the compound represented by formula (1e) as a solid product.

[0067] Compounds represented by formula (1d) and HR 2 The molar ratio to the raw material may be 1:3-15, preferably 1:3.2-10, and more preferably 1:3.5-5.

[0068] According to one specific embodiment of the present invention, HR 2 The starting material is aza-15-crown ether-5.

[0069] Ligand compound synthesis process The ligand compound is obtained by reacting the compound represented by formula (1e) with the compound represented by formula (IV). Specifically, the compound represented by formula (IV) is reacted with sodium methoxide, and then the compound represented by formula (1e) is added and reacted to obtain the ligand compound.

[0070] TIFF0007792471000020.tif23170 (in formula (IV), R 1 is trihalomethyl, preferably trifluoromethyl.

[0071] In some embodiments, sodium methoxide and the compound represented by formula (IV) are dissolved in DME (N,N-dimethylacetamide) to obtain a DME solution, and the compound represented by formula (1e) is added to the DME solution and reacted at room temperature for 18 to 36 hours. After the reaction is completed, the reaction system is adjusted to a pH value of 2 to 3 using dilute hydrochloric acid, and a precipitate is precipitated. The precipitate is filtered, the cake is washed with water, and the cake after washing with water is dried to obtain the ligand compound.

[0072] In the present invention, the molar ratio of the compound represented by formula (1e) to the compound represented by formula (IV) may be 1:3.5 to 6.5, preferably 1:4.5 to 6.5, and more preferably 1:5.5 to 6.0.

[0073] The molar ratio of the compound represented by formula (IV) to sodium methoxide may be 1:1.0 to 1.2, preferably 1:1.0 to 1.1, and more preferably 1:1.0 to 1.05.

[0074] In the present invention, anhydrous sodium sulfate may be used to dry the organic phase.

[0075] <Rare earth supramolecular sensor materials> The rare earth supramolecular sensor material according to the present invention is a compound comprising the ligand compound and a rare earth metal ion RE. 3+ It is formed from, among which, RE 3+ is Sm 3+ ,EU 3+ , Tb 3+ , Er 3+ and Lu 3+ At least one selected from the following is preferably RE 3+ is Sm 3+ ,EU 3+ , Tb 3+ , Er 3+ and Lu 3+ More preferably, it is one selected from RE 3+ is Sm 3+ ,EU 3+ , Tb 3+ , Er 3+ More preferably, it is one selected from RE 3+ EU 3+ is.

[0076] The rare earth supramolecular sensor material of the present invention can capture heavy metal ions, especially cadmium ions, in water. It can realize trace analysis of cadmium ion content, with significantly improved efficiency, sensitivity, and reproducibility. It can identify heavy metal ions and detect their trace levels through changes in fluorescence intensity. The rare earth supramolecular sensor material of the present invention has excellent applicability for detecting heavy metal ions (especially cadmium ions).

[0077] According to one particular embodiment of the invention, R 1 is trifluoromethyl, and R 2 is an aza-15-crown ether-5 substituent, and RE 3+ is EU 3+ The rare earth supramolecular sensor material according to the present invention has the following structure (pseudotetrahedron structure):

[0078] TIFF0007792471000021.tif62170

[0079] <Preparation method of rare earth supramolecular sensor material> The method for preparing a rare earth supramolecular sensor material according to the present invention includes dissolving the rare earth supramolecular sensor material ligand in a C1-C3 alkyl alcohol, and then reacting the ligand with a rare earth chloride in the presence of an alkaline agent to obtain a rare earth supramolecular sensor material.

[0080] In the present invention, the C1-C3 alkyl alcohol may be methanol, ethanol, or isopropyl alcohol, and is preferably ethanol. The alkaline agent is selected from triethylamine or pyridine, and is preferably triethylamine. The rare earth chloride may be a rare earth chloride containing water of crystallization.

[0081] <Use> The present invention further provides a use of the rare earth supramolecular sensor material in detecting the content of heavy metal ions in an aqueous environment, wherein the heavy metal ions comprise cadmium ions.

[0082] Preferably, the heavy metal ions are cadmium ions.

[0083] <Sensor thin film> The present invention further provides a sensor thin film having a thickness of less than 100 nm, which is formed by applying (preferably by spin coating) the rare earth supramolecular sensor material to a substrate, which may be a piece of quartz.

[0084] <Fluorescent probe> The present invention further provides a fluorescent probe comprising the sensor thin film. The gap between the thin films can be utilized to create a reversible fluorescent probe that can be used multiple times, and is suitable for continuous detection of heavy metal ion concentrations in various environments.

[0085] Example 1 Reaction scheme: TIFF0007792471000022.tif82170

[0086] The structural formula of Aza-15-Crown-5 (Japanese: Aza-15-Crown Ether-5) is as follows:

[0087] TIFF0007792471000023.tif29170

[0088] Synthesis of intermediate 1a: m-Iodotoluene (5.00 g, 22.93 mmol) was dissolved in 120 mL of 1,2-dichloroethane, and then acetyl chloride (3.60 g, 45.86 mmol) and anhydrous aluminum trichloride (6.12 g, 45.86 mmol) were added to 60 mL of 1,2-dichloroethane. The mixture was stirred at room temperature for 10 minutes to completely dissolve the anhydrous aluminum trichloride, and then slowly added dropwise to the m-iodotoluene solution. After stirring in an ice bath for 12 hours and confirming the completion of the reaction by TLC, the reaction solution was poured into ice water and allowed to stand for separation. The aqueous layer was extracted with dichloromethane, and the combined organic phase was washed repeatedly with water until neutral. The organic phase was dried over anhydrous sodium sulfate, the solvent was removed, and the residue was separated by silica gel column chromatography. 2.88 g of a pale yellow oily liquid was obtained in 48.37% yield. This gave the compound represented by formula (1a).

[0089] Synthesis of intermediate 1b: m-Acetotoluidine (4.00 g, 26.81 mmol) was dissolved in 150 mL of 1,2-dichloroethane, and acetyl chloride (5.26 g, 67.02 mmol) and anhydrous aluminum trichloride (8.94 g, 67.02 mmol) were added to 80 mL of 1,2-dichloroethane. The mixture was stirred at room temperature for 10 minutes until the anhydrous aluminum trichloride was completely dissolved, and then added in batches to the m-acetotoluidine solution. The mixture was heated to reflux for 4 hours, poured into ice water, and diluted hydrochloric acid was added to adjust the pH of the mixture to 2-3. The mixture was then stirred at room temperature for 1 hour. The pH of the mixture was then adjusted to a slightly alkaline pH and allowed to stand for separation. The aqueous layer was extracted with dichloromethane, and the organic layers were combined. The organic layers were dried over anhydrous sodium sulfate, the solvent was removed, and the residue was separated by silica gel column chromatography. 2.12 g of a pale yellow oily liquid was obtained in 53.00% yield. That is, the compound represented by formula (1b) was obtained.

[0090] Synthesis of intermediate 1c: The obtained intermediate 1a compound (17.44 g, 67.07 mmol) and the obtained intermediate 1b compound (4.00 g, 26.83 mmol) were dissolved in 100 mL of 1,2-o-dichlorobenzene under nitrogen gas protection. Copper powder (17.05 g, 268.28 mmol), 18-crown-6 (0.43 g, 1.61 mmol), and K2CO3 (5.56 g, 40.24 mmol) were added to the solution and heated to reflux for 24 h. After the reaction was completed, the solid was removed by filtration, and the filtrate was washed with dilute aqueous ammonia until colorless, followed by several washes with water. The organic layer was dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure to give a dark brown solid. The crude product was separated by silica gel column chromatography (petroleum ether / ethyl acetate = 5:1 volume ratio) to give 8.78 g of a white solid. The yield was 79.22%. That is, the compound represented by formula (1c) was obtained.

[0091] Synthesis of intermediate 1d: The obtained intermediate 1c compound (5.00 g, 12.10 mmol) was dissolved in 150 mL of acetonitrile, and 7.11 g (39.93 mmol) of NBS (N-bromosuccinimide) reagent was added in batches to the reaction solution while stirring at room temperature. The reaction was allowed to proceed with stirring at room temperature for 24 h. After the reaction was completed, sodium thiosulfate solution was added to reduce the Br2 produced during the reaction. The mixture was then extracted with ethyl acetate (4 × 50 mL). The organic layer was dried over anhydrous sodium sulfate, filtered, and concentrated. The obtained crude product was recrystallized from ethanol to obtain 4.86 g of a pale yellow solid. The yield was 61.73%. This gave the compound represented by formula (1d).

[0092] Synthesis of intermediate 1e: A mixture of aza-15-crown ether-5 (1.00 g, 4.56 mmol) and Cs2CO3 (2.23 g, 6.84 mmol) in 320 mL of anhydrous acetone was heated to reflux for 1 h under nitrogen gas protection. The resulting intermediate 1d compound (0.74 g, 1.10 mmol) was then added and refluxed for 36 h. After refluxing, the reaction temperature was lowered, and the reaction solution was poured into ice water. A large amount of off-white solid was obtained, which was then suction filtered under reduced pressure. The crude product was separated by silica gel column chromatography (petroleum ether / ethyl acetate = 1:3 volume ratio) to obtain 0.66 g of a pale yellow solid. The yield was 54.31%. The hydrogen spectrum of intermediate 1e is shown in Figure 4.

[0093] Synthesis of Ligand Compound I: Sodium methoxide (0.30 g, 5.64 mmol) and ethyl trifluoroacetate (i.e., the compound represented by Formula IV, 0.80 g, 5.64 mmol) were dissolved in 30 mL of DME. The resulting intermediate compound 1e (1.00 g, 0.94 mmol) was added to the solution and reacted at room temperature for 24 h with stirring. After the reaction was completed, the pH of the reaction solution was adjusted to 2-3 with dilute hydrochloric acid. A large amount of yellow precipitate formed. After filtration, the precipitate was washed several times with water and dried to obtain 1.21 g of a yellow solid. No further purification of the product was required. The yield was 95.23%. Thus, ligand compound I was obtained. Its hydrogen spectrum is shown in Figure 5.

[0094] Example 2 Reaction scheme: The resulting ligand compound (0.68 g, 0.50 mmol) of formula (I) was added to 20 mL of methanol, followed by triethylamine (0.20 g, 2.00 mmol). The mixture was stirred thoroughly until the ligand compound was completely dissolved. A 5 mL solution of europium chloride hexahydrate (EuCl3·6H2O) (0.06 g, 0.17 mmol) in methanol was then added. After the addition was complete, the mixture was allowed to react at room temperature for 24 hours. After the reaction was complete, the reaction mixture was filtered, and the resulting filtrate was added to water. A yellow precipitate formed, which was then filtered and dried under vacuum to yield the rare earth supramolecular sensor material.

[0095] Application Example 1 - Ultraviolet absorption spectrum test Nine different concentrations of cadmium ion solution (10 -9 M~10 -1 A rare earth supramolecular sensor material (M) was prepared. 0.02 g of the rare earth supramolecular sensor material prepared in Example 2 was dissolved in 2 mL of N,N-dimethylformamide (DMF). 3 mL of each of the cadmium ion solutions was mixed with the DMF solution of the rare earth supramolecular sensor material and ultrasonicated for 20 minutes. UV absorption spectra were measured for nine solutions with different concentrations, and the results are shown in Figure 1. Figure 1 demonstrates that the rare earth supramolecular sensor material of the present invention has the ability to capture cadmium ions. The absorbance at a wavelength of 260 nm correlated with the cadmium ion concentration. The higher the cadmium ion concentration, the higher the absorbance at 260 nm. Overall, the absorption intensity of cadmium ions was very low, with a weak absorption peak near 260 nm only present when the concentration of the prepared cadmium ion solution reached 0.1 M. This is thought to be due to the fact that cadmium ions have little effect on the fluorescence of the rare earth supramolecular sensor material.

[0096] Application Example 2 - Fluorescence Test Nine different concentrations of cadmium ion solution (10 -9 M~10 -1A solution of cadmium ions (M) was prepared. 0.02 g of the rare earth supramolecular sensor material prepared in Example 2 was dissolved in 2 mL of N,N-dimethylformamide. 3 mL of each of the cadmium ion solutions was mixed with the DMF solution of the rare earth supramolecular sensor material and ultrasonicated for 20 minutes. Fluorescence capture tests were conducted on nine solutions of different concentrations, and the test results are shown in Figure 2. Due to the lack of clarity in the diagram, the highest fluorescence intensities corresponding to cadmium ion solutions of different concentrations are listed in Table 1. The results showed that cadmium ions significantly weakened the fluorescence of the rare earth supramolecular sensor material only when the concentration of the prepared cadmium ion solution reached 0.1 M.

[0097] TIFF0007792471000025.tif46170

[0098] Application Example 3 - Fluorescence Test with Different Metal Ions 1×10 -2 N,N-dimethylformamide solutions of various metal hydrochlorides (M) were prepared. The metal salts included AlCl3, CdCl2, CoCl2, LaCl3, MnCl2, NiCl2, PbCl2, and ZnCl2. 3 ml of each solution was added to 5 mg of the rare earth supramolecular sensor material solid prepared in Example 2 to obtain a solution of rare earth supramolecular sensor material and metal ions. The solution was sonicated for 20 minutes and then left for 12 hours. Fluorescence testing was performed at an excitation wavelength of 298 nm, excitation slit of 2.5 nm, and emission slit of 1.5 nm. Results showed that metal ions other than cadmium ion solution significantly attenuated or quenched the fluorescence of the rare earth supramolecular sensor material. Therefore, the rare earth supramolecular sensor material of the present invention exhibited significant fluorescence detection for the highly toxic heavy metal cadmium ion. This demonstrated that the rare earth supramolecular sensor material prepared in the present invention can achieve fluorescent recognition of the heavy metal cadmium ion.

[0099] Application Example 4 - Fluorescence Test with Different Concentrations of Metal Ions 1×10 -1N,N-dimethylformamide solutions of various metal hydrochlorides were prepared, containing AlCl3, CdCl2, CoCl2, LaCl3, MnCl2, NiCl2, PbCl2, and ZnCl2 as metal salts. 3 ml of each solution was added to 5 mg of the rare earth supramolecular sensor material solid prepared in Example 2 to obtain a solution of rare earth supramolecular sensor material and metal ions. The solution was sonicated for 20 minutes and then allowed to stand for 12 hours. Fluorescence testing was performed at an excitation wavelength of 298 nm, excitation slit 2.5 nm, and emission slit 1.5 nm. The results are shown in Figure 3 (the left column for the same metal ion is 10 -2 The right column shows the fluorescence intensity results for M. -1 The fluorescence intensity results for M are shown in the table. As a result, the fluorescence intensity of each metal ion increased by 10 times (1 × 10 -1 After the increase of M, it was found that metal ions other than cadmium ions quench the fluorescence of the rare earth supramolecular sensor material, demonstrating that the rare earth supramolecular sensor material of the present invention can realize the fluorescent recognition function of cadmium ions.

[0100] Based on the above analysis, trace concentrations of cadmium ions have little effect on the fluorescence intensity of the rare-earth supramolecular sensor material, while some other metal ions significantly reduce or quench the fluorescence of the rare-earth supramolecular sensor material, and the fluorescence intensity increases when the prepared metal ion concentration is increased by 10 times (10 -2 M to 10 -1 M), other metal ions except cadmium ions quench the fluorescence of the rare earth supramolecular sensor material. Therefore, the rare earth supramolecular sensor material prepared in the present invention realizes the fluorescent recognition function of heavy metal cadmium ions, and -9 It was shown that the detection limit was low, reaching below M.

[0101] The present invention is not limited to the above-described embodiments, and all modifications, improvements, substitutions, etc. that can be thought of by those skilled in the art are included within the scope of the present invention, as long as they do not deviate from the spirit of the present invention.

Claims

1. A ligand compound characterized by having a structure represented by the following formula (I): (In formula (I), R １ is trihalomethyl, R ２ is selected from the structures represented by the following formula (II): (In formula (II), X is at least one selected from oxygen and sulfur, and always contains oxygen.)

2. 2. The ligand compound of claim 1, having a structure represented by the following formula:

3. Step (1) of subjecting a compound represented by formula (1c) to a bromine substitution reaction to obtain a compound represented by formula (1d); A compound represented by formula (1d) and H-R ２ Step (2) of reacting the raw material with the compound represented by formula (1e) to obtain the compound represented by formula (1e); and (3) a step of reacting a compound represented by formula (1e) with a compound represented by formula (IV) to obtain the ligand compound; 2. A method for preparing the ligand compound of claim 1, comprising: (In formula (1e), R ２ is selected from the structures represented by the following formula (II): (In formula (II), X is at least one selected from oxygen and sulfur, and always contains oxygen.) (In formula (IV), R １ is trihalomethyl.)

4. In step (1), a compound represented by formula (1c) is reacted with N-bromosuccinimide to obtain a compound represented by formula (1d); In step (2), a compound represented by formula (1d) and H-R ２ and a compound represented by formula (1e) in the presence of cesium carbonate, In step (3), first, the compound represented by formula (IV) is reacted with sodium methoxide, and then the compound represented by formula (1e) is added and reacted to obtain the ligand compound.

4. The method according to claim 3, characterized in that:

5. (i) reacting m-halotoluene with an acetyl halide to form a compound of formula (1a); (ii) reacting m-acetotoluidine with an acetyl halide to form a compound of formula (1b); and (iii) reacting a compound represented by formula (1a) with a compound represented by formula (1b) to obtain a compound represented by formula (1c); further comprising wherein steps (i) and (ii) are performed in any order; The preparation method according to claim 3. (In formula (1a), Y is bromine or iodine.)

6. The ligand compound according to claim 1 or 2 and a rare earth metal ion RE ３＋ A rare earth supramolecular sensor material formed from rare earth metal ions RE ３＋ is Sm ３＋ , Eu ３＋ , Tb ３＋ , Er ３＋ and Lu ３＋ A rare earth supramolecular sensor material characterized by being at least one selected from the following:

7. A method for preparing the rare earth supramolecular sensor material according to claim 6, characterized in that it comprises the steps of dissolving the ligand compound according to claim 1 or 2 in a C1-C3 alkyl alcohol, and reacting it with a rare earth chloride in the presence of an alkaline substance to obtain a rare earth supramolecular sensor material, wherein the alkaline substance is selected from triethylamine or pyridine.

8. 10. The use of the rare earth supramolecular sensor material according to claim 6 in detecting the content of heavy metal ions in an aqueous environment, wherein the heavy metal ions include cadmium ions.

9. A sensor thin film formed by applying the rare earth supramolecular sensor material according to claim 6 to a substrate, the sensor thin film having a thickness of less than 100 nm.

10. A fluorescent probe comprising the sensor thin film according to claim 9.

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