CN110330664B

CN110330664B - Eu/Tb-BHM-COOH complex and preparation method and application thereof

Info

Publication number: CN110330664B
Application number: CN201910651074.4A
Authority: CN
Inventors: 杨朝龙; 贾鹏; 张丹; 李又兵; 高伟宸; 王中豪; 张永锋
Original assignee: Chongqing University of Technology
Current assignee: Chongqing University of Technology
Priority date: 2019-07-18
Filing date: 2019-07-18
Publication date: 2021-08-03
Anticipated expiration: 2039-07-18
Also published as: CN110330664A

Abstract

The invention discloses a Eu/Tb-BHM-COOH complex, a preparation method and application thereof, and belongs to the field of rare earth luminescent materials. The Eu/Tb-BHM-COOH complex mainly consists of EuCl₃·6H₂O、TbCl₃·6H₂O and BHM-COOH. The Eu/Tb-BHM-COOH complex of the metal organic framework material can effectively transfer energy to terbium ions or europium ions, so that the metal organic framework material has high and excellent luminescence performance. Due to Fe³⁺Competitive absorption with the Eu/Tb-BHM-COOH complex results in Fe³⁺So that the Eu/Tb-BHM-COOH complex is Fe³⁺Has selectivity to Fe³⁺Identification and detection are performed.

Description

Eu/Tb-BHM-COOH complex and preparation method and application thereof

Technical Field

The invention relates to the field of rare earth luminescent materials, in particular to a Eu/Tb-BHM-COOH complex and a preparation method and application thereof.

Background

The rare earth element is an IIIB group element in the periodic table of elements and comprises 17 elements, the optical property is determined by the unique 4f electron shell structure of the rare earth element, and the light-emitting characteristic of the rare earth ion is mainly determined by the property of 4f shell electrons of the rare earth ion. With the change of the number of electrons of the 4f shell, the rare earth ions present different electron transition forms and extremely rich energy level transitions. Thus, rare earth ions can absorb or emit light of various wavelengths from the ultraviolet to infrared region to form a wide variety of light emitting materials. The excellent luminescence property of the rare earth ions lays a foundation for preparing high-efficiency luminescent materials by using the rare earth ions.

Metal-organic frameworks (MOFs) are network-structured crystals formed mainly by nitrogen-oxygen multidentate organic ligands of aromatic acids or bases, hybridized with inorganic centers via coordination bonds, and are therefore also referred to as porous coordination polymers. Due to their structural (advances in cluster chemistry) and functional tunability (maturity of organic synthesis associated with ligand preparation and post-synthetic modification), the synthetic tunability of MOFs distinguishes them from traditional porous inorganic materials and allows rational design of many interesting properties, such as stability, porosity, chemical functionality and chirality.

At present, light-emitting metal-organic framework materials have been widely used: such as synthesizing fluorescent sensor, making linear luminous and nonlinear optical elements, and using as photocatalytic material. Among the most practical applications are in the environmental and biological fields. Light-emitting metal organic framework material with both aperture structure and light-emitting functionIs a very potential sensing material. Through the development of decades, many luminescent metal organic framework materials have been widely used in anion, cation, small molecule, steam and other sensing processes. Some pairs of Cu have been prepared²⁺、Zn²⁺、Mg²⁺、Fe³⁺The metal ions and the organic micromolecules are metal organic framework materials with fluorescence recognition capability.

Fe³⁺Widely exists in the nature and human body, plays an important role in the environment and the ecosystem, and is one of trace elements necessary for the human body. Due to Fe³⁺It is commonly existed in biochemical processes of cell metabolism, electron transferase catalysis, oxygen transport, DNA and RNA synthesis, etc., and excess or lack of iron ion can cause physical diseases such as anemia, mental deterioration, arthritis, diabetes, cancer, etc. Thus, for Fe³⁺Detection is extremely important. At present, for Fe³⁺The detection method mainly comprises the following detection methods: spectrophotometry, chromatography, and electrochemical method. These methods are in detecting Fe³⁺The time is long, the needed equipment is large and expensive, and the detection precision is low and insensitive. Therefore, it cannot satisfy the requirement for Fe³⁺Real-time, rapid detection of and not satisfactory at Fe³⁺Detection at lower concentrations is inefficient and sensitive.

Therefore, how to design a Fe-recognition probe³⁺And the metal organic framework material is used for detecting Fe in aqueous solution³⁺Ions, remain a challenge.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide an Eu/Tb-BHM-COOH complex so as to solve the problem that Fe cannot be identified by a metal organic framework material in the prior art³⁺To a problem of (a).

In order to solve the technical problem, the technical scheme adopted by the invention is as follows:

an Eu/Tb-BHM-COOH complex has the following structural general formula:

wherein Ln is Eu and Tb.

The invention also provides a preparation method of the Eu/Tb-BHM-COOH complex, which comprises the following steps:

(1) according to the mol ratio of 1: (6-10): 1, putting hexabromomethylbenzene, dimethyl 5-hydroxyisophthalate and sodium hydroxide into a round-bottom flask, mixing, adding a good solvent, stirring to dissolve a solid, heating a reactant to 60-160 ℃, and carrying out condensation reflux reaction for 8-20 hours; after the reaction is completed, adding excessive ice-cold water into the solution, carrying out rotary evaporation and filtering to obtain a white precipitate, and drying the white precipitate in a vacuum oven for 6 hours to obtain a gray solid; adding the gray solid into a methanol solution, adding a NaOH solution, reacting for 8 hours, acidifying with dilute hydrochloric acid to acidity to obtain a precipitate, washing with deionized water for multiple times, and drying to obtain BHM-COOH; the structural general formula of the BHM-COOH is as follows:

the reaction equation of step (1) is as follows:

(2) the molar ratio (1-12): (1-12): 1 taking EuCl₃·6H₂O、TbCl₃·6H₂O, BHM-COOH, placing in a 20mL reaction kettle, adding deionized water and NaOH solution, stirring the mixture at room temperature for 10-20 min, adding cyclohexanol, and stirring the mixture for 10-30 min; and heating the reaction kettle containing the mixture to 80-120 ℃, and reacting at a constant temperature for 3-6 days to obtain a crude Eu/Tb-BHM-COOH complex product. The reaction equation of step (2) is as follows:

(3) filtering oily impurities from the crude product of the Eu/Tb-BHM-COOH complex while the crude product is hot, washing the crude product with ethanol for a plurality of times, and then drying the crude product in vacuum at 50-70 ℃ for 5-7 hours to obtain the purified Eu/Tb-BHM-COOH complex.

The good solvent in the step (1) is one or more of chloroform, N-dimethylformamide and tetrahydrofuran. And (3) putting the cyclohexanol in the step (2) into an oven at the temperature of 55 ℃ and preserving heat for 0.5h to obtain warm cyclohexanol.

The invention also provides a preparation method of the fluorescent sensor, which uses the Eu/Tb-BHM-COOH complex and specifically comprises the following steps:

a. physically blending the Eu/Tb-BHM-COOH complex and a PLA (polylactic acid) solution, and performing ultrasonic treatment for 30 min;

b. and dripping the film by adopting a tape casting method to prepare the Eu/Tb-BHM-COOH-PLA fluorescent film, namely the fluorescent sensor.

In the step a, the solid-to-liquid ratio of the Eu/Tb-BHM-COOH complex to the PLA solution is 1-5: 1 to 10. The concentration of the PLA aqueous solution is 5-20 g/L.

The invention also discloses a method for identifying Fe by using the fluorescent sensor³⁺The fluorescent sensor is prepared by the preparation method of the fluorescent sensor.

Compared with the prior art, the invention has the following advantages:

1. because the BHM-COOH ligand provided by the invention has twelve coordination sites, and europium ions or terbium ions are grafted on the twelve coordination sites, the coordination capability of the europium ions or terbium ions and the BHM-COOH ligand is enhanced, so that energy can be effectively transferred to the terbium ions or europium ions in the Eu/Tb-BHM-COOH complex which is a metal organic framework material, and the complex has excellent luminescence property. Due to Fe³⁺Competitive absorption with the Eu/Tb-BHM-COOH complex results in Fe³⁺The Eu/Tb-BHM-COOH complex can realize the quenching of the fluorescence intensity of Fe³⁺Selective identification and detection.

2. The Eu/Tb-BHM-COOH complex disclosed by the invention is simple in preparation method, relatively low in cost and suitable for industrial production.

3. The preparation method is simple to operate, short in reaction time and relatively low in cost, and can be used for industrial production.

4. The fluorescent sensor prepared by the invention can realize the aim of Fe³⁺Accurate identification. The Fe can be treated under the condition that single ions exist or multiple ions exist in a mixed manner³⁺Accurate identification and is not affected by anions. By adding Fe with different concentrations dropwise to the fluorescent sensor³⁺The fluorescence lifetime is not changed, and dynamic quenching is eliminated, so that the fluorescence sensor prepared by the invention is used for detecting Fe³⁺The detection of (2) is static quenching. The reason for the quenching is the analyte (Fe)³⁺) Competitive absorption with the complex leads to Fe³⁺Quenching of fluorescence intensity of (1).

The fluorescent sensor prepared by the invention can be used for detecting Fe³⁺The concentration is 3.38X 10^-4M quenches about 80% and has higher detection sensitivity. And the fluorescent sensor is used for detecting Fe³⁺Then the Fe-Fe³⁺And has good repeatable performance. Therefore, the fluorescence sensor prepared by the invention has wide prospect in the fields of pollutant detection and biomedicine.

Drawings

FIG. 1 is an infrared spectrum analysis chart (potassium bromide tablet) of ligand BHM-COOH and complex Eu/Tb-BHM-COOH prepared by the present invention.

FIG. 2 is a fluorescence titration spectrum of fourteen metal ions by the fluorescence sensor prepared in the present invention.

FIG. 3 shows FeCl solutions of different concentrations₃Fluorescence titration spectrum of the solution.

FIG. 4 is a partial enlarged view of FIG. 3, with a wavelength of 500-580 nm.

FIG. 5 shows the dropwise addition of Fe at different concentrations(NO₃)₃Fluorescence titration spectrum of the solution.

FIG. 6 shows a FeCl₃Stern-Volmer curve in solution.

FIG. 7 shows the results obtained with Fe (NO)₃)₃Stern-Volmer curve in solution.

FIG. 8 shows a single ion pair of Fe³⁺The fluorescence titration spectrum of the interference experiment of (1), wherein the ordinate value is the luminescence intensity at 547 nm.

FIG. 9 shows a multi-ion mixed pair of Fe³⁺The fluorescence titration spectrum of the interference experiment of (1), wherein the ordinate value is the luminescence intensity at 547 nm.

FIG. 10 is a graph showing the cyclic titration of Fe for a fluorescence sensor³⁺Wherein the ordinate value is the luminous intensity at 547 nm.

Detailed Description

The invention will be further explained with reference to the drawings and the embodiments.

Preparation of Eu/Tb-BHM-COOH complex

(1) 2.54g (4mmol) of hexabromomethylbenzene and 5.04g (24mmol) of dimethyl 5-hydroxyisophthalate were taken and introduced into a 250mL round-bottomed flask, followed by DMF (50mL), and the mixture solution was heated to 150 ℃ and 0.96g (4mmol) of sodium hydroxide was added and condensed under reflux for 10 hours.

After the reaction was completed, the distillation apparatus was changed to distill off the solvent, and then heated in a vacuum oven at 60 ℃ to obtain a gray solid. The gray solid was added to 120mL of methanol solution, 1.8g of NaOH was added to 30mL of distilled water to prepare NaOH solution, and the NaOH solution was added dropwise to the methanol solution, after 8 hours of reaction, the methanol was removed with a rotary evaporator, and the remaining solution was poured into deionized water (300mL) and acidified with dilute hydrochloric acid to a pH of about 3. After stirring, a precipitated product is obtained. The precipitate was collected by filtration, washed 3 times with deionized water, and dried by vacuum oven overnight at 60 ℃. Obtaining the ligand BHM-COOH.

(2) 0.3g (0.24mmol) of BHM-COOH, EuCl, was weighed₃·6H₂O 0.3225g(0.72mmol)，TbCl₃·6H₂O1.1 g (2.1mmol) in a 50mL reaction vesselTo this solution, 6mL of deionized water and 0.5mL of a 2mol/L NaOH solution were added, and the mixture was stirred at room temperature. After 10min, 7mL of warm cyclohexanol at 55 ℃ were added and the mixture was stirred for 15 min. And (3) placing the reaction kettle in an oven to react for 5 days at the temperature of 100 ℃ to obtain a crude Eu/Tb-BHM-COOH complex product.

(3) Filtering oily impurities from the crude product of the Eu/Tb-BHM-COOH complex while the crude product is hot, washing the crude product with 500ml of ethanol for 3 times, and then drying the crude product in vacuum at 50-70 ℃ for 6 hours to obtain the purified Eu/Tb-BHM-COOH complex.

Infrared spectrum analysis is carried out on the prepared ligand BHM-COOH and the complex Eu/Tb-BHM-COOH, and the analysis result is as described in 1. As can be seen from FIG. 1, the infrared spectra of the ligand BHM-COOH and the complex Eu/Tb-BHM-COOH are very similar and are at 3460cm^-1The left and right parts correspond to-OH characteristic absorption peaks, and the ligand is at 1730cm^-1Has a characteristic absorption peak, is the stretching vibration of C ═ O, and the characteristic absorption peak of the complex is 1623cm^-1And (C) is the stretching vibration of C ═ O. Therefore, the stretching vibration of C ═ O is shifted toward a low wave number because C ═ O and Eu are moved³⁺/Tb³⁺The coordination of (a) results in weakening of the strength thereof. Thus indicating that the preparation of the complex was successful.

Preparation of fluorescent sensor

a. 1g of PLA was taken and put into a single-neck flask, 100ml of chloroform was added thereto, and stirred at room temperature for 2 hours to obtain a 10g/L PLA solution. And physically blending 5mg of prepared Eu/Tb-BHM-COOH complex with 5mL of PLA solution with the concentration of 10g/L, and performing ultrasonic treatment for 30 min.

b. And dripping the film at room temperature by a tape casting method to prepare the Eu/Tb-BHM-COOH-PLA fluorescent film, namely the fluorescent sensor.

Application of fluorescence sensor

Example 1

Respectively taking the prepared M (Cl) by a centrifuge tube_xSolution of said M (Cl)_xThe concentration of the solution is 1 x 10-²mol/L, wherein M is Fe³⁺、Al³⁺、Ba²⁺、Ca²⁺、Co²⁺、Cr³⁺、Cu²⁺、Fe²⁺、K⁺、Mg²⁺、Na⁺、Li⁺、Pb²⁺And Zn²⁺. All fluorescence titration experiments are carried out at the temperature of 25 +/-0.5 ℃, and the Eu/Tb-BHM-COOH-PLA film is respectively placed in a cuvette, 3-5 ml of deionized water is added, and then titration is carried out. 120. mu.L of the above solution was added to each cuvette by a pipette, and the change in fluorescence intensity was observed while recording at an excitation wavelength of 314 nm.

The fluorescence titration spectrum is shown in FIG. 2, with the abscissa representing the fourteen metal ions and the ordinate representing the relative intensity I/I₀. Taking the mixture without adding M (Cl)_xThe fluorescence sensor of the solution served as a control group, and the emission intensity at 547nm was the initial fluorescence emission intensity before titration and was recorded as I₀. Adding M (Cl)_xThe emission intensity of the fluorescence sensor after the solution at 547nm is the fluorescence emission intensity after titration and is marked as I.

As can be seen from FIG. 2, only Fe was added dropwise to the fourteen ions³⁺Obvious change, adding Fe³⁺Then, the relative intensity obtained was about 0.2, and the fluorescence was quenched. And after the other thirteen ions are added, the relative strength is between 0.8 and 1.2, and the change is not obvious. Therefore, the Eu/Tb-BHM-COOH fluorescent sensor prepared by the invention can realize the aim of detecting Fe³⁺Accurate identification of the object.

Example 2

Taking 1 x 10-²FeCl in mol/L₃The solution was gradually dropped (5. mu.L, 10. mu.L, 15. mu.L, 20. mu.L, 25. mu.L, 30. mu.L, 45. mu.L, 55. mu.L, 65. mu.L, 90. mu.L, 120. mu.L) into a cuvette containing a fluorescence sensor, and Fe was detected as a fluorescence sensor pair³⁺The sensitivity of the recognition. The same addition of 1X 10-²mol/L Fe(NO₃)₃Solutions (5. mu.L, 10. mu.L, 15. mu.L, 20. mu.L, 25. mu.L, 30. mu.L, 35. mu.L, 40. mu.L, 50. mu.L, 80. mu.L, 110. mu.L, 140. mu.L) were put into cuvettes in which fluorescence sensors were placed, and the influence of anions on the presence of fluorescence sensors was excluded. FeCl with different concentrations is dripped₃The fluorescence titration spectrum of the solution is shown in figure 3, and the enlarged view of the wavelength of 500-580 nm is shown in figure 4. Adding Fe (NO) with different concentrations dropwise₃)₃The fluorescence titration spectrum of the solution is shown in FIG. 5.

As can be seen from FIGS. 3 to 5, Fe was added³⁺After that, whether by adding FeCl₃Or Fe (NO)₃)₃The fluorescence intensity of the fluorescent probe was as high as about 80% (quenching value ═ fluorescence intensity before quenching-fluorescence intensity after quenching)/fluorescence intensity after quenching, and the fluorescence intensity values were all obtained from 547 nm), and the fluorescent probe had a good recognition effect. To study the effect on Fe in aqueous solution³⁺The quenching ability of an ion, we calculated the quenching constant (K) using the Stern-Volmer (SV) equation (equation 1)_SV)。

I₀/I＝1+K_SV[C] (1)

Wherein I₀To add no Fe³⁺In the case of ions, the fluorescence intensity at 547nm, I is Fe³⁺Luminous intensity at 547nm after ionization, [ C]Is Fe³⁺The concentration of the ions.

Referring to fig. 6 and 7, the quenching curves show good linear dependence. FeCl₃The Ksv value in (A) is 1.45X 10^-4，Fe(NO₃)₃The Ksv value in (A) is 1.27X 10^-4. From this, it was found that the anion-pair fluorescence sensor detects Fe³⁺There is no interference. In addition, the Eu/Tb-BHM-COOH fluorescent sensor prepared by the invention is used for detecting Fe³⁺The detection concentration of (2) reaches 3.38 multiplied by 10^-4M, comparing the detected concentration of other sensors, and determining Fe by using Eu/Tb-BHM-COOH fluorescent sensor³⁺Has good selectivity in detection.

Example 3

Respectively taking the prepared M (Cl) by a centrifuge tube_xSolution of said M (Cl)_xThe concentration of the solution is 1 x 10-²mol/L, wherein M is Fe³⁺、Al³⁺、Ba²⁺、Ca²⁺、Co²⁺、Cr³⁺、Cu²⁺、Fe²⁺、K⁺、Mg²⁺、Na⁺、Li⁺、Pb²⁺And Zn²⁺. Thirteen fluorescence sensors are respectively placed in a cuvette, 3-5 ml of deionized water is added, and Fe is removed³⁺Adding 120 μ L of thirteen solutions except the solution into each cuvette by using a pipette, and adding 120 μ L of solutions into each cuvette by using the pipetteL Fe³⁺The change in fluorescence intensity of the solution was observed with the excitation wavelength of 314nm, and the results are shown in FIG. 8. As can be seen from FIG. 8, one of the thirteen ions was added first, followed by the addition of Fe³⁺Without affecting the fluorescence sensor pair Fe³⁺Identification of (1).

Example 4

Preparing a mixed ion solution, wherein the concentration of ions in the mixed ion solution is 1 × 10-²mol/L. The No. 1 solution is Cr³⁺、Al³⁺、Ca²⁺、Ba²⁺And Co²⁺The solution No. 2 is Li⁺、k⁺、Na⁺、Pb²⁺、Mg²⁺The solution No. 3 is Zn²⁺、Pb²⁺、Cr³⁺、Fe²⁺、Cu²⁺Mixed solution of (4) Li⁺、k⁺、Pb²⁺、Zn²⁺、Cr³⁺、Al³⁺、Ba²⁺、Mg²The mixed solution of No. 5 includes removing Fe³⁺Mixed solution of other thirteen ions. The reconfiguration concentration is 1 × 10-²mol/L of Fe³⁺And (3) solution. Placing five fluorescence sensors in cuvettes respectively, adding 3-5 ml deionized water, dripping 120 mu L of No. 1-5 mixed solution into each cuvette respectively by using a pipettor, and dripping 120 mu L of Fe into each cuvette by using the pipettor³⁺The change in fluorescence intensity of the solution was observed with the excitation wavelength of 314nm, and the results are shown in FIG. 9. As can be seen from FIG. 9, the mixing of multiple ions did not affect the Fe recognition of the fluorescence sensor³⁺Identification of (1).

Example 5

Configuration of Fe³⁺Concentration of 1X 10-²Putting a fluorescence sensor into a cuvette for the mol/L solution, adding 3-5 ml of deionized water, and taking 120 mu L of Fe by using a pipettor³⁺The solution was added dropwise to a cuvette and the fluorescence intensity was recorded and observed at an excitation wavelength of 314 nm. Then the used fluorescence sensor is washed by deionized water for 3 times, and then Fe is dripped³⁺And (3) solution. Repeating the step of adding Fe dropwise for 10 times³⁺The solution and washing with deionized water for 3 times, and inspectingThe lifetime of the fluorescence sensor. The detection results are shown in fig. 10.

As can be seen from FIG. 10, although the Eu/Tb-BHM-COOH fluorescent sensor is paired with Fe³⁺The quenching effect of (2) is very obvious, the intensity is high, but the fluorescence intensity can still be recovered to a very high level after deionized water is washed for a plurality of times. The fluorescent sensor prepared by the invention has good repeatability, can be used for multiple times and still maintains the Fe³⁺Accurate identification of the object.

The fluorescent sensor prepared by the invention can realize the aim of Fe³⁺Accurate identification. The Fe can be treated under the condition that single ions exist or multiple ions exist in a mixed manner³⁺Accurate identification and is not affected by anions. The fluorescent sensor prepared by the invention can be used for detecting Fe³⁺The concentration is 3.38X 10^-4M quenches about 80% and has higher detection sensitivity. And the fluorescent sensor is used for detecting Fe³⁺Then the Fe-Fe³⁺And has good repeatable performance. Therefore, the fluorescence sensor prepared by the invention has wide prospect in the fields of pollutant detection and biomedicine.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the technical solutions, and those skilled in the art should understand that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all that should be covered by the claims of the present invention.

Claims

1. Use of fluorescent sensor for identifying Fe³⁺The application of (2) is characterized in that the fluorescence sensor is obtained by adopting the following preparation method, and specifically comprises the following steps:

a. physically blending the Eu/Tb-BHM-COOH complex and a PLA solution, and performing ultrasonic treatment for 30 min; wherein the solid-to-liquid ratio of the Eu/Tb-BHM-COOH complex to the PLA solution is (1-5): (1-10); the concentration of the PLA aqueous solution is 5-20 g/L;

b. dripping the film by adopting a tape casting method to prepare a Eu/Tb-BHM-COOH-PLA fluorescent film, namely the fluorescent sensor;

wherein, the Eu/Tb-BHM-COOH complex has the following structural general formula:

；

wherein Ln is Eu and Tb.

2. Use of a fluorescence sensor for the identification of Fe according to claim 1³⁺The Eu/Tb-BHM-COOH complex is prepared by the following method, and comprises the following steps:

(1) according to the mol ratio of 1: (6-10): 1, putting hexabromomethylbenzene, dimethyl 5-hydroxyisophthalate and sodium hydroxide into a round-bottom flask, mixing, adding a good solvent, stirring to dissolve a solid, heating a reactant to 60-160 ℃, and carrying out condensation reflux reaction for 8-20 hours; after the reaction is completed, adding excessive ice-cold water into the solution, carrying out rotary evaporation and filtering to obtain a white precipitate, and drying the white precipitate in a vacuum oven for 6 hours to obtain a gray solid; adding the gray solid into a methanol solution, adding a NaOH solution, reacting for 8 hours, acidifying with dilute hydrochloric acid to acidity to obtain a precipitate, washing with deionized water for multiple times, and drying to obtain BHM-COOH;

(2) the molar ratio (1-12): (1-12): 1 taking EuCl₃·6H₂O、TbCl₃·6H₂O, BHM-COOH, placing in a 20mL reaction kettle, adding deionized water and NaOH solution, stirring the mixture at room temperature for 10-20 min, adding cyclohexanol, and stirring the mixture for 10-30 min; heating the reaction kettle containing the mixture to 80-120 ℃, and reacting at a constant temperature for 3-6 days to obtain a crude Eu/Tb-BHM-COOH complex product;

3. Use of a fluorescence sensor for the identification of Fe according to claim 2³⁺The application of (A), wherein the structural general formula of the BHM-COOH is as follows:

。

4. use of a fluorescence sensor for the identification of Fe according to claim 2³⁺The method is characterized in that the good solvent in the step (1) is one or more of chloroform, N-dimethylformamide and tetrahydrofuran.

5. Use of a fluorescence sensor for the identification of Fe according to claim 2³⁺The method is characterized in that the cyclohexanol in the step (2) is placed in an oven at 55 ℃ and is kept warm for 0.5h to obtain warm cyclohexanol.