Ligand compound, rare earth supermolecular sensor material, sensor thin film, fluorescent probe and preparation method, and use

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 preparation method and use thereof.

Background Art

[0002] Heavy metals include gold, silver, copper, iron, mercury, lead, cadmium, etc. From the perspective of environmental pollution, heavy metals mainly refer to heavy elements with strong biotoxicity such as mercury, cadmium, lead, chromium, and arsenic, which is a semi-metal. Since heavy metals are difficult to biodegrade, they are concentrated thousands of times under the biological enrichment effect of the food chain and finally enter the human body. Heavy metals may strongly interact with proteins and enzymes in the human body to inactivate them, or accumulate in some organs of the human body to cause chronic poisoning.

[0003] As is well known, cadmium is a highly toxic heavy metal, and most of its compounds are toxic substances. Sewage containing cadmium discharged from industries pollutes river water and farmland. Cadmium is more easily absorbed by crops, vegetables, and rice than other heavy metals. When contaminated crops are eaten by humans, cadmium also enters the human body through the digestive tract and is mainly accumulated in the liver and kidneys, causing disorders. Long-term intake of cadmium affects the functions of human hematopoiesis, nerves, kidneys, and other organs, and causes great harm to the health of humans, especially children. Cadmium has a great destructive power on the human central nervous system. After cadmium poisoning enters the human body, it is extremely difficult to excrete, and it is very likely to seriously interfere with kidney function and reproductive function. Cadmium replaces calcium in bones, causing severe softening of bones and bone fractures. In addition, cadmium may cause gastric dysfunction, reduce the ratio of zinc to cadmium, and cause an increase in hypertension. "Itai-itai disease" is also a typical example of chronic cadmium poisoning, which is caused by the pollution of the human living environment by cadmium, affects a wide range, causes many victims, and has been recognized as a "public nuisance disease".

[0004] In addition, cadmium pollution has the characteristics of a long cycle and high concealment. Cadmium is potentially toxic and can accumulate in human tissues (especially in women) even when the cadmium concentration in drinking water is as low as 0.1 milligram per liter. Its latency period is as long as 10 to 30 years, and it is difficult to detect medical symptoms in the initial stage.

[0005] Currently, traditional methods such as atomic absorption spectrometry, atomic fluorescence spectrometry, and inductively coupled plasma method can meet the needs of accuracy and precision, and the technology is mature. However, the necessary detections take time, special sample treatment is required to reduce noise interference, and large experimental equipment is needed, so their use is limited to scientific research institutions only.

[0006] Crown ether is a kind of cyclic compound composed of polyether units, has strong metal complexing properties, and is useful as a metal ion scavenger. CN110394166A discloses a crown ether-type lignin-based adsorbent and its manufacturing method, which are manufactured using an aminocrown ether compound and lignin as raw materials and utilizing the Mannich reaction. The adsorbent is used in fields such as the treatment of wastewater containing heavy metal ions such as mercury, lead, and copper, and the purification of water resources.

[0007] How to capture heavy metal ions, identify heavy metal ions through changes in luminescence signals or fluorescence intensities, and achieve qualitative or quantitative trace detection and analysis of heavy metal ions is a concern of researchers. CN109897317A discloses a cellulose nanocrystal-rare earth complex-polyvinyl alcohol composite hydrogel fluorescence probe that constructs a rare earth europium complex in a cross-linkable reversible hydrogel to enable the detection of heavy metal ions in the water environment. In this patent document, by using a cellulose nanocrystal / polyvinyl alcohol composite gel, the mechanical properties of the fluorescence probe are improved, enabling the detection of heavy metal ions. Summary of the Invention

[0008] One object of the present invention is to provide a ligand compound that can be used for detecting the content of heavy metal ions in an aqueous environment, and in particular, can form a rare earth metal ion and a rare earth supramolecular sensor material for realizing 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 that can detect the content of heavy metal ions, especially cadmium ions, in an aqueous environment with high sensitivity, 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 the use 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 represented by formula (I).

[0010] TIFF2025082248000002.tif64170(In formula (I), R 1 is trihalomethyl, and R 2 is selected from the structures represented by the following formula (II).

[0011] TIFF2025082248000003.tif29170(In formula (II), X is at least one selected from oxygen and sulfur and necessarily contains oxygen.))

[0012] According to the ligand compound of the present invention, preferably, it has a structure represented by the following formula.

[0013] TIFF2025082248000004.tif62170

[0014] In another aspect, the present invention Step (1) of subjecting the compound represented by formula (1c) to a bromine substitution reaction to obtain the compound represented by formula (1d), The compound represented by formula (1d) and H-R 2Step (2) of reacting with a raw material to obtain a 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, A method for preparing the ligand compound including the above is provided.

[0015] TIFF2025082248000005.tif95170 (In formula (1e), R 2 is selected from the structures represented by the following formula (II). TIFF2025082248000006.tif35170 (In formula (II), X is at least one selected from oxygen and sulfur, and necessarily contains oxygen.)) TIFF2025082248000007.tif23170 (In formula (IV), R 1 is trihalomethyl.)

[0016] According to the preparation method of the present invention, preferably, In step (1), the compound represented by formula (1c) is reacted with N-bromosuccinimide to obtain a compound represented by formula (1d), In step (2), the compound represented by formula (1d) is reacted with an H-R 2 compound in the presence of cesium carbonate to obtain a compound represented by formula (1e), 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, Step (i) of reacting m-halotoluene with an acetyl halide to form a compound represented by formula (1a), Step (ii) of reacting m-acetotoluidine with an acetyl halide to form a compound represented by formula (1b), and Step (iii) of reacting the compound represented by formula (1a) with the compound represented by formula (1b) to obtain the compound represented by the above formula (1c), further comprising Among them, steps (i) and (ii) may be in any order.

[0018] TIFF2025082248000008.tif24170 (In formula (1a), Y is bromine or iodine.) TIFF2025082248000009.tif25170

[0019] In another aspect, the present invention provides a rare earth supramolecular sensor material formed from the ligand compound and rare earth metal ions RE 3+ wherein the rare earth metal ions RE 3+ are at least one selected from Sm 3+ , Eu 3+ , Tb 3+ , Er 3+ and Lu 3+ The present invention further provides a rare earth supramolecular sensor material.

[0020] In another aspect, the present invention provides a method for preparing the rare earth supramolecular sensor material, which comprises dissolving the ligand compound in a C1-C3 alkyl alcohol and reacting it in the presence of a rare earth chloride and 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 provides the use of the rare earth supramolecular sensor material in detecting the heavy metal ion content in an aqueous environment, wherein the heavy metal ions include cadmium ions.

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

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

[0024] The present invention uses a tri-β-diketone having a triphenylamine skeleton as a ligand, coordinates with a rare earth metal ion (especially europium ion) to realize the fluorescence response of the rare earth metal ion, and introduces an azacrown ether as a recognition group for heavy metal ions at the meta-position of the amine group in the triphenylamine skeleton, so that heavy metal ions, especially cadmium ions, can be captured. When the nitrogen on the benzene ring coordinates to the ligand, it affects the energy transfer from the ligand to the rare earth metal ion (especially europium ion), resulting in the fluorescence enhancement phenomenon of the rare earth supramolecular sensor material according to the present invention. The rare earth supramolecular sensor material according to the present invention can realize the analysis of the content of trace heavy metal ions (especially cadmium ions) in water, improve the analysis efficiency, sensitivity and reproducibility, and has a low detection limit. The reaction conditions of the preparation method according to the present invention are mild and safe. The products of the ligand compound and the rare earth supramolecular sensor material can also reach a purity of 99.0% or more. The present invention can further prepare a nanoscale sensor thin film (film thickness < 100 nm) by spin-coating the rare earth supramolecular sensor material on a quartz wafer, and can create a reversible fluorescence probe that can be used multiple times by utilizing the voids between the thin films, realize the analysis of the content of trace cadmium ions, improve the efficiency and reduce the cost.

Brief Description of Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0026] Hereinafter, the present invention will be further described with reference to specific examples, but the scope of the claims of the present invention is not limited thereto.

[0027] <Explanation of Terms> 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 those skilled in the technical field to which the present invention belongs. Methods and materials similar or equivalent to those described in this application can be used in the implementation or testing of the present invention. Appropriate methods and materials will be described below. All publications, patent applications, patents, and other references mentioned in this application are hereby incorporated by reference in their entirety into the specification. In case of conflict, the specification and the definitions included therein shall prevail. Also, the materials, methods, preparation examples, and examples are merely illustrative and are not intended to be limiting.

[0029] <Ligand Compound> The ligand compound according to the present invention can form a rare earth metal ion and a rare earth supramolecular sensor material, and the formed rare earth supramolecular sensor material is used to capture heavy metal ions, particularly cadmium ions, in water. This is used for trace analysis of heavy metal ions in the water environment. 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 the formula (I).

[0031] TIFF2025082248000010.tif64170 (In the formula (I), R 1is trihalomethyl. For example, it is trifluoromethyl, trichloromethyl or tribromomethyl, preferably trifluoromethyl.) R 2 is selected from the structures represented by the following formula (II).

[0032] TIFF2025082248000011.tif30170(In formula (II), X is at least one selected from oxygen and sulfur and necessarily contains oxygen.)

[0033] In some embodiments, all of the Xs are oxygen. In other embodiments, some of the Xs are oxygen and some of the Xs are sulfur.

[0034] According to one embodiment of the present invention, R in the structure represented by formula (I) 1 is trifluoromethyl, in formula (II), all of the Xs are oxygen, and the ligand compound according to the present invention has the structure represented by the following.

[0035] TIFF2025082248000012.tif62170

[0036] As a result of intensive research, the present inventors have used a tri-β-diketone having a triphenylamine skeleton as a ligand, coordinated with a rare earth metal ion (especially europium ion) to realize the fluorescence response of the rare earth metal ion, and introduced an azacrown ether as a recognition group for heavy metal ions at the meta-position of the amine group of the triphenylamine skeleton, whereby heavy metal ions, especially 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, causing a fluorescence enhancement phenomenon of the rare earth supramolecular sensor material.

[0037] After introducing an azacrown ether as a recognition group for heavy metal ions at the meta-position of the amine group in the triphenylamine skeleton synthesized in the present invention, the resulting rare earth supramolecular sensor material exhibits a fluorescence response to heavy metal ions, particularly cadmium ions. When the concentration of the captured heavy metal ions (particularly cadmium ions) reaches a certain level, fluorescence attenuation or fluorescence quenching occurs. Such a rare earth supramolecular sensor material produces fluorescence of different intensities in samples with different ion concentrations and can be detected with a fluorometer.

[0038] <Method for Preparing Ligand Compound> The present invention further provides a method for preparing the ligand compound including the synthesis step (1) of the compound represented by formula (1d), the synthesis step (2) of the compound represented by formula (1e), and the synthesis step (3) of the ligand compound. Optionally, it further includes the synthesis step (i) of the compound represented by formula (1a), the synthesis step (ii) of the compound represented by formula (1b), and the synthesis step (iii) of the compound represented by formula (1c). Among them, steps (i) and (ii) may be in any order. The following will be described in detail.

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

[0040] TIFF2025082248000013.tif24170 (In formula (1a), Y is bromine or iodine.)

[0041] m-Halotoluene may be m-chlorotoluene, m-bromotoluene or m-iodotoluene, preferably m-iodotoluene. 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 aluminum trichloride anhydrous 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, 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. The combined organic phase is washed with water until neutral, and the organic phase is dried and concentrated to obtain a concentrate. The concentrate is subjected to column chromatography (eluent for column chromatography: petroleum ether / ethyl acetate) to obtain a compound represented by the formula (1a) as an oily liquid.

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

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

[0045] TIFF2025082248000014.tif27170

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

[0047] TIFF2025082248000015.tif25170 Acetyl halide may be acetyl chloride or acetyl bromide, 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 aluminum trichloride anhydrous 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 while heating under reflux. After the reaction is completed, 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 h. Then, the pH is adjusted to weakly basic, allowed to stand and separated, the organic layer is collected, and the aqueous layer is extracted with dichloromethane or chloroform. The organic phases are combined. The organic phase is dried and concentrated to obtain a concentrate. The concentrate is subjected to column chromatography (eluent for column chromatography: petroleum ether / ethyl acetate) to obtain an oily liquid. That is, the compound represented by the formula (1b) is obtained.

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

[0050] According to one specific embodiment of the present invention, the specific reaction formula is as follows.

[0051] TIFF2025082248000016.tif29170

[0052] Synthesis process of the compound represented by formula (1c) That is, it is a synthesis step of intermediate 1c. The compound represented by the formula (1a) and the compound represented by the formula (1b) are reacted to obtain the compound represented by the formula (1c).

[0053] TIFF2025082248000017.tif39170

[0054] In this step, the solvent is 1,2-o-dichlorobenzene, and copper powder, 18-crown-6 and potassium carbonate are used as reaction aids. Specifically, copper powder is used as a catalyst, 18-crown-6 is used as a phase transfer catalyst, and potassium carbonate is used as an alkali agent.

[0055] In some embodiments, intermediate 1a and intermediate 1b are dissolved in 1,2-o-dichlorobenzene under the protection of an inert gas, copper powder, 18-crown-6 and potassium carbonate are added to this solution, and the reaction is carried out for 18 to 32 h (hours) while heating under reflux. After the reaction is completed, solid-liquid separation is carried out to remove the solid, the mother liquor is washed with ammonia and then washed with water, and the organic layer is taken out. The organic layer is dried and concentrated to obtain a concentrate, and the concentrate is separated by column chromatography (eluent: petroleum ether / ethyl acetate, volume ratio of both = 5:1) to obtain a solid. That is, the compound represented by formula (1c) is obtained.

[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, 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 process of the compound represented by formula (1d) That is, it is the synthesis step of intermediate 1d. The compound represented by formula (1c) is subjected to a bromine substitution reaction to obtain the compound represented by formula (1d).

[0059] TIFF2025082248000018.tif45170

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

[0061] In some embodiments, the intermediate 1c is dissolved in acetonitrile to obtain an acetonitrile solution. NBS is added to the acetonitrile solution in batches. After the addition is complete, the reaction is carried out at room temperature with continuous stirring for 18 to 36 h. After the reaction is completed, it is reduced with sodium thiosulfate, and then extracted multiple times with ethyl acetate. The extracted organic layer is collected, dried, filtered and concentrated. The concentrate is recrystallized to obtain a solid. That is, the compound represented by formula (1d) is obtained.

[0062] The molar ratio of the 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, it is the synthesis step of the intermediate 1e. The compound represented by formula (1d) and H-R 2 are reacted to obtain the compound represented by formula (1e). Specifically, the compound represented by formula (1d) and H-R 2 are reacted in the presence of cesium carbonate to obtain the compound represented by formula (1e).

[0064] TIFF2025082248000019.tif45170H-R 2 The structural formula of is as follows.

[0065] TIFF2025082248000020.tif28170(Here, X is at least one selected from oxygen and sulfur, and must contain oxygen.)

[0066] In some embodiments, H-R is added to anhydrous acetone 2The mixture of the raw material and cesium carbonate is reacted for 1 - 1.5 h while heating under reflux under the protection of an inert gas, and then the compound represented by formula (1d) is added to the reaction system, and the reaction is continued for 24 - 38 h while refluxing. After the reaction is completed, the temperature is lowered, the reaction solution is quenched by pouring it into ice water, and solid-liquid separation is carried out to obtain a crude solid product. The crude solid product is separated by column chromatography (petroleum ether / ethyl acetate, volume ratio of both = 1:3) to obtain the compound represented by formula (1e) as a solid product.

[0067] The compound represented by formula (1d) and H-R 2 The molar ratio of the compound represented by formula (1d) 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, H-R 2 The raw material is aza-15-crown ether-5.

[0069] Synthesis process of the ligand compound The compound represented by formula (1e) and the compound represented by formula (IV) are reacted to obtain the ligand compound. 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] TIFF2025082248000021.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, the compound represented by formula (1e) is added to the DME solution, and the reaction is carried out at room temperature for 18 - 36 h. After the reaction is completed, the reaction system is adjusted to a pH value of 2 - 3 using dilute hydrochloric acid, a precipitate is deposited, 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 the formula (1e) to the compound represented by the 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 the 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 for drying the organic phase.

[0075] <Rare earth supramolecular sensor material> The rare earth supramolecular sensor material according to the present invention is formed from the ligand compound and rare earth metal ions RE 3+ , wherein RE 3+ is at least one selected from Sm 3+ , Eu 3+ , Tb 3+ , Er 3+ and Lu 3+ . Preferably, RE 3+ is one selected from Sm 3+ , Eu 3+ , Tb 3+ , Er 3+ and Lu 3+ . More preferably, RE 3+ is one selected from Sm 3+ , Eu 3+ , Tb 3+ , Er 3+ . Even more preferably, RE 3+ is Eu 3+ .

[0076] The rare earth supramolecular sensor material according to the present invention can capture heavy metal ions, especially cadmium ions, in water. Microanalysis of the cadmium ion content can be realized, and the efficiency, sensitivity, and reproducibility can be significantly improved. Heavy metal ions can be identified through changes in fluorescence intensity, and their trace levels can be detected. The rare earth supramolecular sensor material according to the present invention has excellent applicability for the detection of heavy metal ions (especially cadmium ions).

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

[0078] TIFF2025082248000022.tif62170

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

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

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

[0082] Preferably, the heavy metal ion is a cadmium ion.

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

[0084] <Fluorescent probe> The present invention further provides a fluorescent probe comprising the sensor thin film. A reversible fluorescent probe that can be used multiple times by utilizing the gaps between the thin films can be prepared and can be suitably used for continuously detecting the heavy metal ion concentration in various environments.

[0085] Example 1 Reaction formula: TIFF2025082248000023.tif82170

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

[0087] TIFF2025082248000024.tif29170

[0088] Synthesis of intermediate 1a: m-Iodotoluene (5.00 g, 22.93 mmol) was dissolved in 120 mL of 1,2-dichloroethane, and 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. After stirring for 10 minutes at room temperature until anhydrous aluminum trichloride was completely dissolved, it was slowly added dropwise to the m-iodotoluene solution. The mixture was stirred in an ice bath for 12 h. After confirming the completion of the reaction by TLC, the reaction solution was poured into ice water and allowed to stand for liquid separation. The aqueous layer was extracted with dichloromethane, the organic phases were combined, 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. A pale yellow oily liquid (2.88 g) was obtained in a yield of 48.37%. That is, the compound represented by formula (1a) was obtained.

[0089] Synthesis of Intermediate 1b: m-Acettoluidine (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 anhydrous aluminum trichloride was completely dissolved, and then added to the m-acettoluidine solution in one batch. The mixture was heated to reflux for 4 h, the reaction solution was poured into ice water, dilute hydrochloric acid was added to adjust the pH of the mixture to 2 - 3, and the mixture was stirred at room temperature for 1 h. Next, the pH of the mixture was adjusted to weakly alkaline and allowed to stand for liquid separation. The aqueous layer was extracted with dichloromethane, the organic phases were combined, the organic phase was dried over anhydrous sodium sulfate, the solvent was removed, and the residue was separated by silica gel column chromatography. A pale yellow oily liquid (2.12 g) was obtained in a yield of 53.00%. 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 the protection of nitrogen gas. Copper powder (17.05 g, 268.28 mmol), 18-crown-6 (0.43 g, 1.61 mmol) and K 2 CO 3 (5.56 g, 40.24 mmol) were added to the above solution, and the mixture was heated to reflux for 24 h. After completion of the reaction, the mixture was filtered to remove the solid, and the filtrate was washed with dilute aqueous ammonia until it became colorless, and then washed several times with water. The organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure to obtain a black-brown solid. The crude product was separated by silica gel column chromatography (volume ratio of petroleum ether / ethyl acetate = 5:1) to obtain 8.78 g of a white solid. The yield was 79.22%. That is, the compound represented by the 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 batchwise to the reaction solution stirred at room temperature. The reaction was carried out for 24 h while stirring at room temperature. After completion of the reaction, a sodium thiosulfate solution was added to reduce Br 2 generated in the reaction. Then, it was 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%. That is, the compound represented by the formula (1d) was obtained.

[0092] Synthesis of intermediate 1e: Aza-15-crown ether-5 (1.00 g, 4.56 mmol) and Cs 2 CO 3(2.23 g, 6.84 mmol) of the mixture was heated under reflux for 1 h under the protection of nitrogen gas. Then, the obtained intermediate 1d compound (0.74 g, 1.10 mmol) was added, and the mixture was continuously refluxed for 36 h. After refluxing, the reaction temperature was lowered, the reaction solution was poured into ice water, a large amount of off-white solid was obtained, and the off-white solid was obtained by suction filtration under reduced pressure. The crude product was separated by silica gel column chromatography (volume ratio of petroleum ether / ethyl acetate = 1:3), and 0.66 g of a pale yellow solid was obtained. 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, and the obtained intermediate 1e compound (1.00 g, 0.94 mmol) was added to the solution, and the reaction was carried out with stirring at room temperature for 24 h. 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 was generated, and after filtration, the precipitate was washed several times with water, and the precipitate was dried to obtain 1.21 g of a yellow solid. The product did not need to be further purified. The yield was 95.23%. That is, ligand compound I was obtained. Its hydrogen spectrum is shown in Figure 5.

[0094] Example 2 Reaction formula: The obtained ligand compound (0.68 g, 0.50 mmol) represented by formula (I) was added to 20 mL of methanol, and triethylamine (0.20 g, 2.00 mmol) was added, and the mixture was stirred well until the ligand compound was completely dissolved, and europium chloride hexahydrate EuCl 3 ·6H 2 O (0.06 g, 0.17 mmol) in 5 mL of methanol solution was added. After the dropping was completed, the reaction was carried out at room temperature for 24 h. After the reaction was completed, the reaction solution was filtered, the obtained filtrate was added to water, a yellow precipitate was precipitated, filtered, and vacuum dried to obtain a rare earth supramolecular sensor material.

[0095] Application Example 1 - Ultraviolet absorption spectrum test Nine different concentrations of cadmium ion solutions (10 -9 M~10 -1 M) were prepared. 0.02 g of the rare earth supramolecular sensor material prepared in Example 2 above was taken and dissolved in 2 ml of N,N-dimethylformamide (DMF) solution. 3 mL of multiple types of cadmium ion solutions were each mixed with the DMF solution of the rare earth supramolecular sensor material and subjected to ultrasonic treatment for 20 min. Ultraviolet absorption spectrum tests were performed on nine different concentrations of solutions, and the test results are shown in Figure 1. From Figure 1, it was found that the rare earth supramolecular sensor material according to the present invention has the ability to capture cadmium ions. The absorbance at a wavelength of 260 nm was correlated with the concentration of cadmium ions. The higher the concentration of cadmium ions, the higher the absorbance at a wavelength of 260 nm. Overall, the absorption intensity of cadmium ions is very low, and only when the concentration of the prepared cadmium ion solution reaches 0.1 M, there is a weak absorption peak near 260 nm, which is considered to be a factor that cadmium ions hardly affect the fluorescence of the rare earth supramolecular sensor material.

[0096] Application Example 2 - Fluorescence test Nine different concentrations of cadmium ion solutions (10 -9 M~10 -1 M) were prepared. 0.02 g of the rare earth supramolecular sensor material prepared in Example 2 above was taken and dissolved in 2 ml of N,N-dimethylformamide solution. 3 mL of multiple types of cadmium ion solutions were each mixed with the DMF solution of the rare earth supramolecular sensor material and subjected to ultrasonic treatment for 20 min. Fluorescence capture tests were performed on nine different concentrations of solutions, and the test results are shown in Figure 2. Since the drawings are not clear, in the present invention, the highest fluorescence intensity corresponding to different concentrations of cadmium ion solutions is listed in Table 1. As a result, it was shown that cadmium ions significantly weaken the fluorescence of the rare earth supramolecular sensor material only when the concentration of the prepared cadmium ion solution reaches 0.1 M.

[0097] TIFF2025082248000026.tif46170

[0098] Application Example 3 - Fluorescence test with different metal ions 1×10 -2 N,N-dimethylformamide solutions of various metal hydrochlorides of 1×10 3 M were prepared. As metal salts, AlCl 2 3, CdCl 2 2, CoCl 3 2, LaCl 2 2, MnCl 2 2, NiCl 2 2, PbCl 2 2, and ZnCl

[0099] Application Example 4 - Fluorescence test with different concentrations of metal ions 1×10 -1 N,N-dimethylformamide solutions of various metal hydrochlorides of 1×10 3 M were prepared. As metal salts, AlCl 2 3, CdCl 2 2, CoCl 3 2, LaCl 2 2, MnCl 2 2, NiCl 2 2, PbCl 2It contains, and 3 ml of each of the solutions was put into 5 mg of the rare earth supramolecular sensor material solid prepared in Example 2 to obtain a solution of the rare earth supramolecular sensor material and metal ions. After ultrasonic treatment for 20 min, it was left standing for 12 h. A fluorescence test was carried out under the conditions of an excitation wavelength of 298 nm, an excitation slit of 2.5 nm, and an emission slit of 1.5 nm. The results are shown in Fig. 3 (the left column of the same metal ion represents the fluorescence intensity results of 10 -2 M, and the right column represents the fluorescence intensity results of 10 -1 M.). As a result, after the concentration of each metal ion increased by 10 times (1×10 -1 M), it was found that other metal ions except cadmium ions quenched the fluorescence of the rare earth supramolecular sensor material. The rare earth supramolecular sensor material according to the present invention has shown that it can realize the fluorescence 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, but several other metal ions significantly reduce or quench the fluorescence of the rare earth supramolecular sensor material. When the prepared metal ion concentration increases by 10 times (from 10 -2 M to 10 -1 M), other metal ions except cadmium ions quench the fluorescence of the rare earth supramolecular sensor material. From this, the rare earth supramolecular sensor material prepared in the present invention has realized the fluorescence discrimination function of heavy metal cadmium ions and has shown a low detection limit reaching below 10 -9 M.

[0101] The present invention is not limited to the above embodiments, and all possible deformations, improvements, substitutions, etc. that can be conceived by those skilled in the art within the scope not departing from the gist of the present invention are included in the scope of the present invention.

Claims

1. A ligand compound 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 according to claim 1, characterized in that it has a structure represented by the following formula:

3. (1) a step 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); and (3) 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 according to 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 reacting the compound with the compound represented by formula (1e) in the presence of cesium carbonate to obtain a compound represented by formula (1e), 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 process 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: The process is characterized in that steps (i) and (ii) are carried out 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 a rare earth metal ion RE ３＋ is Sm ３＋ , Eu ３＋ , Tb ３＋ , Er ３＋ and Lu ３＋ The rare earth supramolecular sensor material is at least one selected from the following:

7. The 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 C1-C3 alkyl alcohol, and reacting it with 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.

8. 7. 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, characterized in that said heavy metal ions include cadmium ions.

9. A sensor thin film formed by applying the rare earth supramolecular sensor material according to claim 6 onto 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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