Preparation method of rare earth luminescent metal-organic framework material and application of rare earth luminescent metal-organic framework material as heavy metal ion fluorescence detection agent

Abstract

The invention provides a preparation method of a rare earth luminescent metal-organic framework material and application of the rare earth luminescent metal-organic framework material as a heavy metal ion fluorescence detection agent, La (III) and Dy (III) are used as metal centers, terephthalic acid is used as a ligand, and the rare earth metal-organic framework material is synthesized under the condition that a template agent is added or not added. And the template agent can realize the regulation and control of the morphology and the size of the product. According to the prepared rare earth luminescent metal-organic framework material, DyMOF is extremely sensitive to heavy metal ions and is quick in response, the fluorescence intensity of DyMOF is gradually reduced along with increase of the amount of the heavy metal ions, and finally a fluorescence quenching phenomenon occurs. LaMOF is extremely sensitive to heavy metal ions such as Cu < 2 + >, Fe < 3 + > and Mn < 2 + >, the fluorescence intensity of LaMOF is gradually reduced along with the increase of the quantity of the ions, and fluorescence quenching occurs when the heavy metal ions reach a certain quantity. In the future, the MOFs are expected to be used for developing fluorescence sensors, fluorescence probes and the like for detecting heavy metal ions.

Description

Technical Field

[0001] The present invention relates to the technical fields of the preparation of metal-organic framework materials and heavy metal detection, and specifically relates to a preparation method of a rare earth luminescent metal-organic framework material and its application as a fluorescent detection agent for heavy metal ions. Background Art

[0002] In 1995, American chemist Yaghi and his colleagues proposed the concept of "Metal-Organic Frameworks (MOFs)", and systematically explored the potential of such materials as porous materials. MOFs have rapidly become a research hotspot in the field of materials science due to their highly ordered structure, adjustable pore size, large specific surface area, and potential for various applications.

[0003] In recent years, the application scope of coordination polymers and MOFs has rapidly expanded to many fields. Researchers have achieved fine control over the structure and properties of coordination polymers by precisely controlling the types of metal centers and organic ligands, coordination modes, and polymerization conditions, further promoting the optimization of material properties and the discovery of new functions. With the increasing attention to environmental issues, recent research has focused more on the green synthesis methods, biodegradability of coordination polymers, and their applications in environmental protection (such as pollutant adsorption and decomposition).

[0004] Currently, the problem of heavy metal pollution has become a globally concerned environmental issue, and heavy metal pollution seriously endangers the ecological environment safety and the survival and development of humans. In terms of the ecological environment, the accumulation of heavy metals in the soil can lead to the destruction of soil structure and the decline of fertility, and the accumulation in organisms such as soil microorganisms, plants, and animals causes toxicity; for the survival and development of humans, after heavy metals enter the human body through the food chain and accumulate, they may cause chronic toxicity and lead to various health problems, including cancer and neurological diseases. In addition, some heavy metals may also have genetic toxicity, affecting the human reproductive system and the health of future generations. Therefore, the detection and treatment of heavy metal pollution are very important, and there is an urgent need for a new and effective means to detect heavy metals in wastewater. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention proposes a preparation method of a rare earth luminescent metal-organic framework material and its application as a fluorescent detection agent for heavy metal ions. The prepared product has the unique structure and surface characteristics of MOFs, enabling it to efficiently capture heavy metal ions and detect them through fluorescence sensing technology, which provides a new approach and method for the monitoring and treatment of heavy metal pollution. This rare earth luminescent metal-organic framework material has important application prospects in treating heavy metal pollution in water bodies.

[0006] For the above purposes, the technical solution adopted by the present invention is as follows:

[0007] A preparation method of a rare earth luminescent metal-organic framework material, using La(Ⅲ) and Dy(Ⅲ) as metal centers and terephthalic acid as a ligand, synthesizing a rare earth metal-organic framework material [La 2 (BDC) 3 (H 2 O) 4 n 、[Dy 2 (BDC) 3 (H 2 O) 4 n under the condition of adding or not adding a template agent (CTAB), and the template agent can realize the regulation of the product morphology and size.

[0008] As a preferred technical solution of the present invention, the raw materials used in the preparation method are disodium terephthalate and lanthanum nitrate or dysprosium chloride with a molar ratio of 3:2.

[0009] As a preferred technical solution of the present invention, when adding a template agent (CTAB) in the preparation method, the mass ratio between the template agent (CTAB) and lanthanum nitrate or dysprosium chloride is 1-10:1.

[0010] As a preferred technical solution of the present invention, the disodium terephthalate in the preparation method is prepared by reacting terephthalic acid with a sodium hydroxide solution.

[0011] As a preferred technical solution of the present invention, the reaction temperature used in the preparation method is room temperature, and the reaction time is 30 min - 3 h.

[0012] Compared with the prior art, the beneficial effects of the present invention are shown in:

[0013] (1) The present invention synthesizes metal-organic framework materials with different sizes and morphologies using a stirring synthesis method, with dysprosium and lanthanum as metal centers and terephthalic acid as a ligand, and the crystal size and morphology can be adjusted by changing the addition amount of the template agent.

[0014] (2) For the rare earth luminescent metal-organic framework material prepared by the present invention, DyMOF is extremely sensitive and has a fast response to heavy metal ions such as Co 2+ 、Cu 2+ 、Fe 3+ 、Mn 2+ . And as the amount of heavy metal ions increases, its fluorescence intensity gradually decreases, and finally fluorescence quenching occurs. LaMOF is sensitive to Cu 2+ 、Fe 3+ 、Mn​​2+ They are extremely sensitive to heavy metal ions such as, and as the amount of ions increases, their fluorescence intensity gradually decreases. When the heavy metal ions reach a certain amount, fluorescence quenching occurs. All these indicate that DyMOF and LaMOF are sensitive to some heavy metal ions and can respond within a short time. These two kinds of MOFs prepared in the present invention both have excellent water stability, and in the future, it is expected to develop fluorescence sensors, fluorescence probes, etc. for detecting heavy metal ions by using MOFs. Description of the Drawings

[0015] Figure 1 XRD patterns of [Dy 2 (BDC) 3 (H 2 O) 4 n prepared under different reaction conditions.

[0016] Figure 2 XRD patterns of [La 2 (BDC) 3 (H 2 O) 4 n prepared under different reaction conditions.

[0017] Figure 3 SEM images of [Dy 2 (BDC) 3 (H 2 O) 4 n prepared without adding CTAB at different reaction times. The reaction times are (a) 30 min and (b) 3 h respectively.

[0018] Figure 4 SEM images of [Dy 2 (BDC) 3 (H 2 O) 4 n prepared with different amounts of CTAB added. The amounts of CTAB added are (a) 0 g, (b) 0.2 g, (c) 0.4 g, and (d) 0.8 g respectively.

[0019] Figure 5 SEM images of [La 2 (BDC) 3 (H 2 O) 4 n prepared without adding CTAB at different reaction times. The reaction times are (a) 30 min and (b) 3 h respectively.

[0020] Figure 6 ​​​​​SEM images of [La 2 (BDC) 3 (H 2 O) 4 n prepared with different masses of CTAB added: CTAB addition amounts: (a) 0 g, (b) 0.2 g, (c) 0.4 g, (d) 0.8 g.

[0021] Figure 7 Variation of the fluorescence intensity of DyMOF when different volumes of cobalt ion solution are added.

[0022] Figure 8 Variation of the fluorescence intensity of DyMOF when different volumes of copper ion solution are added.

[0023] Figure 9 Variation of the fluorescence intensity of DyMOF when different volumes of iron ion solution are added.

[0024] Figure 10 Variation of the fluorescence intensity of DyMOF when different volumes of manganese ion solution are added.

[0025] Figure 11 Variation of the fluorescence intensity of DyMOF when different volumes of nickel ion solution are added.

[0026] Figure 12 Variation of the fluorescence intensity of LaMOF when different volumes of cobalt ion solution are added.

[0027] Figure 13 Variation of the fluorescence intensity of LaMOF when different volumes of copper ion solution are added.

[0028] Figure 14 Variation of the fluorescence intensity of LaMOF when different volumes of iron ion solution are added.

[0029] Figure 15 Variation of the fluorescence intensity of LaMOF when different volumes of manganese ion solution are added.

[0030] Figure 16 Variation of the fluorescence intensity of LaMOF when different volumes of nickel ion solution are added. Detailed implementation method

[0031] Example 1

[0032] In this example, the rare earth luminescent metal-organic framework material [Dy 2 (BDC) 3 (H 2 O) 4 n is prepared without a template, and the steps are as follows: ​​

[0033] (1) Preparation of disodium terephthalate:

[0034] Weigh an appropriate amount of solid sodium hydroxide particles and prepare a 25 mL sodium hydroxide solution with a concentration of 4 M. Weigh 1.660 g of terephthalic acid and add it to 5 mL of this sodium hydroxide solution. After the reaction, dry it in a vacuum drying oven, and then reflux with ethanol for 3 h to remove impurities, thus obtaining disodium terephthalate (Na 2 BDC), dissolve it in water to prepare a sodium salt solution for storage and standby.

[0035] (2) Preparation of [Dy 2 (BDC) 3 (H 2 O) 4 n :

[0036] Weigh 0.113 g (0.3 mmol) of DyCl 3 and dissolve it in 15 mL of water. Dropwise add the sodium salt solution to the DyCl 3 solution (control the molar ratio of disodium terephthalate to dysprosium chloride to be 3:2), and stir and react at room temperature for 30 min to obtain a white solid. After filtering the white solid product, wash it with water and alcohol, and dry it naturally to obtain the rare earth luminescent metal-organic framework material [Dy 2 (BDC) 3 (H 2 O) 4 n , labeled as DyMOF-30min.

[0037] Example 2

[0038] The difference between this example and Example 1 is only that the stirring reaction time in step (2) is 3 h, and the prepared product is labeled as DyMOF-3h.

[0039] Examples 3-5

[0040] In this example, the rare earth luminescent metal-organic framework material [Dy 2 (BDC) 3 (H 2 O) 4 n is prepared under the condition of the presence of a template, and the steps are as follows:

[0041] (1) Preparation of disodium terephthalate:

[0042] Same as Example 1.

[0043] (2) [Dy 2 (BDC) 3 (H 2 O)​​​4 n (Preparation):

[0044] Weigh 0.113 g (0.3 mmol) of DyCl 3 Dissolve it in 15 mL of water, add an appropriate amount of CTAB and stir evenly until the template agent is completely dissolved. Then, dropwise add the sodium salt solution (control the molar ratio of disodium terephthalate to dysprosium chloride to be 3:2), and stir and react at room temperature for 3 h to obtain a white solid. After filtering the white solid product, wash it with water and alcohol, and dry it naturally to obtain the rare earth luminescent metal-organic framework material [Dy 2 (BDC) 3 (H 2 O) 4 n

[0045] Control the CTAB addition amounts corresponding to Examples 3, 4, and 5 to be 0.2 g, 0.4 g, and 0.8 g, respectively. The finally prepared products are labeled as DyMOF-0.2 g CTAB-3 h, DyMOF-0.4 g CTAB-3 h, and DyMOF-0.8 g CTAB-3 h.

[0046] Example 6

[0047] In this example, the rare earth luminescent metal-organic framework material [La 2 (BDC) 3 (H 2 O) 4 n is prepared as follows:

[0048] (1) Preparation of disodium terephthalate:

[0049] Same as Example 1.

[0050] (2) Preparation of [La 2 (BDC) 3 (H 2 O) 4 n :

[0051] Weigh 0.097 g (0.3 mmol) of La(NO 3 ) 3 Dissolve it in 15 mL of water, and dropwise add the sodium salt solution to the La(NO 3 ) 3 solution (control the molar ratio of disodium terephthalate to lanthanum nitrate to be 3:2), and stir and react at room temperature for 30 min to obtain a white solid. After filtering the white solid product, wash it with water and alcohol, and dry it naturally to obtain the rare earth luminescent metal-organic framework material [La 2 ​​​​(BDC) 3 (H 2 O) 4 n , labeled as LaMOF-30min.

[0052] Example 7

[0053] The difference between this example and Example 1 is only that the stirring reaction time in step (2) is 3 h, and the prepared product is labeled as LaMOF-3h.

[0054] Examples 8-10

[0055] In this example, rare earth luminescent metal-organic framework materials [La 2 (BDC) 3 (H 2 O) 4 n are prepared as follows:

[0056] (1) Preparation of disodium terephthalate:

[0057] Same as Example 1.

[0058] (2) Preparation of [La 2 (BDC) 3 (H 2 O) 4 n :

[0059] Weigh 0.097 g (0.3 mmol) of La(NO 3 ) 3 and dissolve it in 15 mL of water. Add an appropriate amount of CTAB and stir evenly until the template agent is completely dissolved. Then, dropwise add the sodium salt solution (control the molar ratio of disodium terephthalate to lanthanum nitrate to be 3:2), and stir and react at room temperature for 3 h to obtain a white solid. After filtering the white solid product, wash it with water and alcohol, and dry it naturally to obtain the rare earth luminescent metal-organic framework material [La 2 (BDC) 3 (H 2 O) 4 n

[0060] Control the CTAB addition amounts corresponding to Examples 8, 9, and 10 to be 0.2 g, 0.4 g, and 0.8 g, respectively. The finally prepared products are labeled as LaMOF-0.2g CTAB-3h, LaMOF-0.4g CTAB-3h, and LaMOF-0.8gCTAB-3h.

[0061] Example 11 - Characterization Example ​​​​

[0062] Preparation and characterization of rare earth luminescent metal-organic framework materials:

[0063] 1. Preparation of [Dy 2 (BDC) 3 (H 2 O) 4 ] n XRD characterization:

[0064] pass Figure 1 It can be seen from the comparison with the standard spectrum that the peak position of the synthesized sample product XRD spectrum is consistent with the standard spectrum, indicating that the target product has been synthesized. Wherein when the reaction conditions are to add 0g CTAB and stir the synthesis for 30min, the peak area of ​​its diffraction peak is the largest, indicating that the crystallinity of the metal-organic framework synthesized under this condition is higher than the product degree under the remaining several conditions. Therefore, when the subsequent fluorescence performance test is performed, the sample (sample prepared in Example 1) in which 0g CTAB is added and stirred for synthesis for 30min is selected. The metal-organic framework synthesized by Dy as the metal center has strong stability in water and does not collapse when encountering water.

[0065] 2. [La under different reaction conditions 2 (BDC) 3 (H 2 O) 4 ] n XRD characterization:

[0066] pass Figure 2 It can be concluded from the comparison with the standard spectrum that the peak position of the synthesized sample product XRD spectrum is consistent with the standard spectrum, indicating that the target product has been synthesized. When the reaction conditions are to add 0.2g CTAB and stir the synthesis for 3h, its diffraction peak area is larger, indicating that the crystallinity of the metal-organic framework generated under this condition is higher than the product degree under several other conditions. Therefore, when the subsequent fluorescence performance is detected, the sample (prepared sample in Example 8) when adding 0.2g CTAB and stirring the synthesis for 3h is selected. The stability of the metal-organic framework made by La as the metal center in water is not strong, and the product synthesized under the stirring synthesis for 30min will collapse when it encounters water.

[0067] 3. Preparation of [Dy 2 (BDC) 3 (H 2 O) 4 ] n SEM test:

[0068] from Figure 3It can be seen that the product is in irregular block shape. When the reaction time is prolonged, the sample does not show any obvious changes except that the diameter increases slightly. This result shows that the extent to which the product morphology can be adjusted by regulating the reaction time is limited.

[0069] 4. Add different amounts of CTAB to assist in the preparation of [Dy 2 (BDC) 3 (H 2 O) 4 ] n SEM test:

[0070] pass Figure 4 It can be seen that after the product is modified by adding CTAB, the structure becomes more regular and presents a rod-like structure. As the amount of CTAB added increases, the product gradually becomes regular from the initial rod-like shape. This result shows that the purpose of adjusting the morphology of nanocrystals can be achieved by regulating the amount of CTAB added. The product in Figure a presents an irregular block structure, while the morphology in Figure b has already taken the initial shape of a rod. The product in Figure c presents a rod-like structure, and Figure d presents a more regular rod-like structure. In summary, when 0.8g CTAB is added, the morphology of the nanocrystals is relatively good.

[0071] 5. Preparation of [La 2 (BDC) 3 (H 2 O) 4 ] n SEM test:

[0072] from Figure 5 It can be seen that the product presents a rice grain structure. As the reaction time increases, the nanorods grow into stacked nanorods. This result shows that the product morphology can be controlled by adjusting the reaction time.

[0073] 6. Add different amounts of CTAB to assist in the preparation of [La 2 (BDC) 3 (H 2 O) 4 ] n SEM test:

[0074] from Figure 6It can be seen that after being modified by CTAB, the product grows into beautiful flower-like shapes. The overall morphology of the synthesized metal-organic framework is more regular and the structure is clear. In Figure a, the product shows a rod-like structure formed by stacking, with the rudiment of an independent cluster structure. It can be seen from Figure b that the morphology of the product has grown into a stacked cluster structure. In Figure c, a stacked cluster structure is presented, resembling a flower, and in Figure d, a stacked flocculent structure is shown. Based on the above, when 0.4 g of CTAB is added, the morphology of the nanocrystals is relatively excellent.

[0075] Example 12 - Application Example

[0076] Application of the rare earth luminescent metal-organic framework materials prepared in Examples 1 and 8 in the fluorescence detection of heavy metal ions:

[0077] To explore the sensitivity of metal-organic framework materials to heavy metal ions, the fluorescence sensitivities of DyMOF-30min and LaMOF-0.2 g CTAB-3h prepared in Examples 1 and 8 to Co 2+ , Cu 2+ , Fe 3+ , Mn 2+ , Ni 2+ were investigated respectively.

[0078] 1. Experimental method:

[0079] Take 2 mL of absolute ethanol and the product to be tested and put them into a cuvette. After mixing, put it into a fluorescence spectrometer for detection and record the fluorescence data. Then continuously and microscopically add 0.1 M heavy metal ion solution to the cuvette with the absolute ethanol solvent, and draw a fluorescence intensity spectrum to observe the change trend of the fluorescence intensity (excitation wavelength Ex = 300 nm).

[0080] 2. Fluorescence sensing properties of DyMOF-30min:

[0081] ① Sensitivity to Co 2+

[0082] As Figure 7 can be seen, when 0.01 mL of cobalt ion solution is added to ethanol, its fluorescence intensity begins to decline. During the process of adding cobalt ion solution from 0.01 mL to 0.05 mL, the decline trend of the fluorescence intensity is relatively fast. When the volume of the cobalt ion solution continues to increase, the fluorescence intensity no longer decreases significantly; when the volume of the added cobalt ion solution reaches 2.2 mL, an obvious fluorescence quenching phenomenon occurs. These all indicate that DyMOF has strong sensitivity to cobalt ions.

[0083] ② Sensitivity to Cu 2+

[0084] As Figure 8It can be seen that when 0.002 mL of copper ion solution is added to the ethanol solution, its fluorescence intensity begins to decrease. Until 0.06 mL is added, the decreasing trend of the fluorescence intensity is relatively stable. When the copper ion solution is continuously added, the decrease in fluorescence intensity is no longer as obvious as at the beginning. When the volume of the added copper ion solution reaches 0.350 mL, fluorescence quenching occurs. All these indicate that DyMOF is highly sensitive to copper ions.

[0085] ③ Sensitivity to Fe 3+ Sensitivity

[0086] From Figure 9 It can be seen that when 0.002 mL of iron ion solution is added thereto, its fluorescence intensity begins to decrease. When the volume of the iron ion solution is continuously increased, the fluorescence intensity always shows a stable decreasing trend. When the volume of the added iron ion solution reaches 0.300 mL, fluorescence quenching occurs. All these indicate that DyMOF is highly sensitive to iron ions and has a good response.

[0087] ④ Sensitivity to Mn 2+ Sensitivity

[0088] From Figure 10 It can be seen that when 0.002 mL of manganese ion solution is added, the fluorescence intensity shows an obvious decreasing trend. Until 0.02 mL is added, the fluorescence intensity decreases rapidly. After that, when added again, the decrease in fluorescence intensity is not as rapid as at the beginning. Until 0.6 mL is added, a very obvious fluorescence quenching occurs. All these indicate that the fluorescence intensity of DyMOF is extremely sensitive to manganese ions.

[0089] ⑤ Sensitivity to Ni 2+ Sensitivity

[0090] From Figure 11 It can be seen that until 0.175 mL of nickel ion solution is added to the cuvette, the obvious decrease in fluorescence intensity can be observed. After adding 1.2 mL of nickel ion solution and continuing to add the solution, the fluorescence intensity does not change significantly. It can be seen that at this time, the fluorescence intensity has reached the lowest point and fluorescence quenching does not occur. All these indicate that the fluorescence intensity of DyMOF is less sensitive to nickel ions than the other several heavy metal ions in the experimental tests.

[0091] 3. Fluorescence sensing properties of LaMOF - 0.2g CTAB - 3h:

[0092] ① Sensitivity to Co 2+ Sensitivity

[0093] From Figure 12It can be seen that when a small amount of cobalt ion solution is dropped into the sample, the fluorescence intensity can be significantly enhanced. Subsequently, when the amount of cobalt ion solution is continuously increased, the fluorescence intensity continues to increase, and reaches the strongest when 0.01 mL is added. When the cobalt ion solution is continuously dropped thereafter, the fluorescence intensity remains unchanged. Thus, it can be seen that the fluorescence sensitivity of LaMOF to heavy metal ions is very strong at extremely small amounts, but there is no longer a response after reaching a certain amount.

[0094] ② Sensitivity to Cu 2+

[0095] From Figure 13 it can be seen that when 0.002 mL of copper ion solution is added to the cuvette, the peak value of its fluorescence intensity decreases. When the volume of the copper ion solution is continuously increased, the peak value of the fluorescence intensity continues to decrease. During this process, the fluorescence intensity always maintains a stable downward trend; when the volume of the copper ion solution added reaches 0.45 mL, a fluorescence quenching phenomenon occurs. This indicates that LaMOF is sensitive to copper ions, and the synthesized LaMOF has an excellent response to copper ions, indicating that the performance of the synthesized product is good.

[0096] ③ Sensitivity to Fe 3+

[0097] From Figure 14 it can be seen that when 0.001 mL of iron ion solution is added to the cuvette, the fluorescence intensity starts to respond and decreases significantly. During the subsequent continuous dropping of the iron ion solution, the fluorescence intensity always maintains a stable decrease until 0.15 mL of the iron ion solution is dropped, and an obvious fluorescence quenching phenomenon occurs. These all indicate that the fluorescence intensity of LaMOF is very sensitive to iron ions and has a fast response, and the performance of the synthesized product is good.

[0098] ④ Sensitivity to Mn 2+

[0099] From Figure 15 it can be seen that when 0.0002 mL of manganese ion solution is added to the cuvette, the peak value of the fluorescence intensity decreases significantly. Until 0.0005 mL of manganese ion solution is dropped, the fluorescence intensity is rapidly decreasing. When the manganese ion solution is continuously dropped thereafter, the downward trend of the fluorescence intensity slows down. Finally, when 1.1 mL of manganese ion solution is dropped, an obvious quenching phenomenon occurs. These all indicate that the fluorescence intensity of LaMOF has extremely strong sensitivity to manganese ions, and LaMOF can detect and respond even when containing extremely small amounts of manganese ions.

[0100] ⑤ Sensitivity to Ni 2+

[0101] From Figure 16 ​​​​It can be seen that when nickel ion solutions with different volumes are added, the variation trend of the fluorescence intensity changes. When 0.0002 mL of nickel ion solution is added, the peak value of its fluorescence intensity becomes larger. Continuing to add nickel ion solution, it can be seen that the peak value continues to increase and finally reaches the maximum at 0.010; when the volume of nickel ion solution is continuously increased to 0.014 mL, the fluorescence intensity begins to decrease. When the nickel ion solution continues to increase, the fluorescence intensity slowly decreases and drops to 1500 a.u. when it is added to 0.25 mL; when the volume of nickel ion solution is further increased, the fluorescence intensity basically fluctuates slightly around 1500 a.u. and no quenching phenomenon occurs. All these indicate that the fluorescence intensity of LaMOF is not sensitive to nickel ions.

[0102] The above content is only an example and explanation of the concept of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar ways to replace them. As long as they do not deviate from the concept of the invention or exceed the scope defined by this claim book, they should all belong to the protection scope of the present invention.

Claims

1. A method for preparing a rare earth luminescent metal-organic framework material, characterized in that: Using La(Ⅲ) and Dy(Ⅲ) as metal centers and terephthalic acid as ligand, rare earth metal-organic framework materials [La2(BDC)3(H2O)4] were synthesized with or without the addition of template (CTAB). n 、[Dy2(BDC)3(H2O)4] n , the template can achieve the regulation of product morphology and size.

2. The preparation method according to claim 1, characterized in that The raw materials used in the reaction are disodium terephthalate and lanthanum nitrate or dysprosium chloride in a molar ratio of 3:

2.

3. The preparation method according to claim 2, characterized in that: When the template (CTAB) is added, the mass ratio between the template (CTAB) and lanthanum nitrate or dysprosium chloride is 1-10:

1.

4. The preparation method according to claim 2, characterized in that: The disodium terephthalate is prepared by reacting terephthalic acid with a sodium hydroxide solution.

5. The preparation method according to claim 1, characterized in that: The reaction temperature is room temperature and the reaction time is 30min-3h.

6. Use of the rare earth luminescent metal-organic framework material prepared by the method according to any one of claims 1 to 5 as a heavy metal ion fluorescent detection agent.

7. The use according to claim 6, characterized in that The heavy metal ion is Co 2+ , Cu 2+ , Fe 3+ , Mn 2+ 、Ni 2+ .

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