Three-dimensional Tb-MOF compound as well as preparation method and application thereof

Abstract

The invention discloses a three-dimensional Tb-MOF compound and a preparation method and application thereof, the chemical formula of Tb-MOF is {[H2N (CH3) 2] (H3O) [Tb (btec) (HCOO) (H2O) 3]} n, and btec is a ligand pyromellitic acid. The preparation method comprises the following steps: enabling terbium salt, ligand N, N-bis (3, 5-dicarboxylphenyl) pyromellitic diimide and N, N-dimethylformamide and diluted hydrochloric acid to react at 120-150 DEG C for 24-72 hours, after the reaction is finished, naturally cooling to normal temperature, filtering, washing and drying to obtain the three-dimensional Tb-MOF compound. The three-dimensional Tb-MOF compound can be used for detecting 4-hydroxybenzaldehyde and a metal ion Al < 3 + >.

Description

Technical Field

[0001] The present invention relates to metal-organic framework-based luminescent materials, and particularly to a three-dimensional Tb-MOF compound, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of technology, people's living standards have been greatly improved, but hazards such as environmental pollution, food poisoning, and ecological damage have also followed. Among them, aluminum ions are relatively common metal ions in life, but when their content exceeds the normal range, they will pose a hazard to people's health. The toxicity of aluminum is relatively slow and not easily detectable in the initial stage. Only when it accumulates to a certain extent will there be toxic reactions of metabolic disorders. Research shows that excessive Al3+ can cause neurodegenerative diseases and metabolic system disorders, and is significantly associated with the pathogenesis of various malignant tumors.

[0003] On the other hand, 4-hydroxybenzaldehyde is an important intermediate in the pharmaceutical industry and the fragrance industry, and plays a huge role in the synthesis of the pharmaceutical industry and the fragrance industry. However, 4-hydroxybenzaldehyde is a common toxic gas in indoor decoration materials, which is very harmful to the human body and may cause olfactory, gustatory, and digestive system diseases, and may even cause cancer. Due to its strong carcinogenicity and multi-organ toxicity, it is listed as a Class II hazardous chemical by the World Health Organization. Therefore, developing a detection method for 4-hydroxybenzaldehyde and metal ion Al 3+ has become a technical challenge that urgently needs to be broken through in the fields of environmental monitoring and health protection.

[0004] Currently, the detection technologies widely used for 4-hydroxybenzaldehyde and metal ion Al 3+ include high performance liquid chromatography (HPLC), inductively coupled plasma (ICP), electrochemical analysis technology, atomic absorption spectrometry (AAS), etc.; due to disadvantages such as complex operation, high use cost, and poor detection effect, their applications are limited. It is worth noting that luminescent metal-organic framework materials (LMOFs) have been widely used in the detection fields of ions, volatile organic compounds (VOCs), antibiotics, and biomarkers due to their characteristics such as optical tunability and fluorescence diversity. In particular, lanthanide metal-organic frameworks (Ln-MOFs) have excellent luminescent characteristics such as strong emission peaks, long luminescence lifetimes, and high luminescence efficiencies, and are more favored in the field of fluorescence sensors.

[0005] However, there are two major key shortcomings in the existing technologies: First, there is still a technological gap in the detection of 4-hydroxybenzaldehyde by LMOF-based fluorescent probes. Existing research mainly focuses on traditional volatile organic compounds such as formaldehyde and nitro compounds. Second, for the detection of Al3+ by the reported LMOF fluorescent probes, the response mode is generally fluorescence quenching type, which is prone to false positives due to interference from environmental factors. However, there are few research reports on ratio-type sensors based on dual emission peak self-calibration. Such technological bottlenecks seriously restrict the development process of on-site rapid detection equipment and are even more difficult to meet the urgent need for synchronous monitoring of multiple pollutants in complex matrices. Therefore, developing a multifunctional material based on LMOF materials for detecting 4-hydroxybenzaldehyde and metal ion Al 3+ is of great significance. Summary of the Invention

[0006] The purpose of the present invention is to provide a three-dimensional Tb-MOF compound, its preparation method and application, which can efficiently and selectively recognize 4-hydroxybenzaldehyde and metal ion Al 3+ .

[0007] In one aspect of the present invention, a three-dimensional Tb-MOF compound is proposed. According to an embodiment of the present invention, the chemical formula of the compound is {[H2N(CH3)2](H3O)[Tb(btec)(HCOO)(H2O)3]}, where btec is the ligand benzene-1,2,4,5-tetracarboxylic acid. n , in which btec is the ligand benzene-1,2,4,5-tetracarboxylic acid.

[0008] In another aspect of the present invention, a preparation method of a three-dimensional Tb-MOF compound is proposed. According to an embodiment of the present invention, the method includes the following steps: reacting a terbium salt, the ligand N,N-bis(3,5-dicarboxyphenyl)pyromellitimide, N,N-dimethylformamide and dilute hydrochloric acid at 120-150 °C for 24-72 h, and after the reaction is completed, naturally cooling to room temperature, filtering, washing and drying to obtain the three-dimensional Tb-MOF compound.

[0009] In addition, according to the preparation method of a three-dimensional Tb-MOF compound in the above embodiment of the present invention, the following additional technical features may also be included:

[0010] In some embodiments of the present invention, the terbium salt is at least one of terbium nitrate and terbium chloride.

[0011] In some embodiments of the present invention, the molar ratio of the terbium salt, the ligand N,N-bis(3,5-dicarboxyphenyl)pyromellitimide to N,N-dimethylformamide is (1.5-2.5):1:(520-780).

[0012] In some embodiments of the present invention, the concentration of the dilute hydrochloric acid is 0.5-1.5 mol / L, and the molar ratio of the dilute hydrochloric acid to the terbium salt is 1:(15-40).

[0013] In another aspect of the present invention, the present invention provides a fluorescence detection material. According to the embodiments of the present invention, the material includes the three-dimensional Tb-MOF compound, and the fluorescence detection material is used to detect 4-hydroxybenzaldehyde or metal ion Al 3+ .

[0014] In another aspect of the present invention, the present invention provides a fluorescence detection method. According to the embodiments of the present invention, the method includes the following steps: dispersing the crystalline material of the three-dimensional Tb-MOF compound in an N,N-dimethylformamide solution to obtain a Tb-MOF suspension, adding the solution containing the analyte to the Tb-MOF suspension and shaking well, waiting for 30-240 s, and collecting the fluorescence emission spectrum of the mixture using a fluorescence spectrometer. The method is used to detect 4-hydroxybenzaldehyde or metal ion Al 3+ .

[0015] In addition, according to a fluorescence detection method of the above embodiments of the present invention, the following additional technical features may also be provided:

[0016] In some embodiments of the present invention, when the analyte is 4-hydroxybenzaldehyde, the ratio of the fluorescence intensities at 543 nm before and after adding the solution containing the analyte is calculated to determine the concentration of 4-hydroxybenzaldehyde; when the analyte is metal ion Al 3+ , the ratio of the fluorescence intensities at 543 nm and 362 nm is calculated to determine the concentration of Al 3+ ; the concentration of Al 3+ in the solution containing the analyte is 0-1.38 mmol / L; the concentration of 4-hydroxybenzaldehyde in the solution containing the analyte is 0-1.60 mmol / L.

[0017] In some embodiments of the present invention, the concentration of the Tb-MOF suspension is 0.5-1.0 mg / mL.

[0018] In another aspect of the present invention, the present invention provides a luminescent material. According to the embodiments of the present invention, it includes the three-dimensional Tb-MOF compound.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1) The three-dimensional Tb-MOF compound prepared by the present invention has excellent luminescence characteristics such as strong emission peaks, long luminescence lifetimes, and high luminescence efficiencies.

[0021] 2) The present invention provides a fluorescence detection material, which is equivalent to constructing a quenching-type fluorescence sensor for the detection of 4-hydroxybenzaldehyde and a dual-emission ratio-type fluorescence sensor for the detection of metal ion Al 3+ When 4-hydroxybenzaldehyde is added to the Tb-MOF suspension, the fluorescence of Tb-MOF at 543 nm is completely quenched, and the quenching efficiency is as high as 95.8%. When metal ion Al 3+ is added, the fluorescence intensity of the Tb-MOF suspension at 543 nm decreases, and at the same time, the fluorescence intensity at 362 nm increases. It shows that the three-dimensional Tb-MOF synthesized by this method has good application potential in the detection of 4-hydroxybenzaldehyde and metal ion Al 3+ . BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the coordination environment of Tb ions and the coordination mode diagram of ligand btec in the three-dimensional Tb-MOF compound in Example 2 of the present invention (a), the single-capped square antiprismatic structure of Tb1 (b) and the binuclear structure diagram of Tb-MOF (c); 3+

[0023] Figure 2 is the one-dimensional chain structure (a) and three-dimensional supramolecular network structure (b) of the Tb-MOF compound in Example 2 of the present invention;

[0024] Figure 3 is the fluorescence spectrum diagram (a) of the three-dimensional Tb-MOF compound in Application Example 2 of the present invention in response to different concentrations of 4-hydroxybenzaldehyde and the detection calibration curve (b) of 4-hydroxybenzaldehyde;

[0025] Figure 4 is the bar chart of the fluorescence detection of 4-hydroxybenzaldehyde by the three-dimensional Tb-MOF compound in Application Example 2 of the present invention under the interference of other aldehyde components;

[0026] Figure 5 is the fluorescence spectrum diagram (a) of the three-dimensional Tb-MOF compound in Application Example 3 of the present invention in response to different concentrations of Al 3+ and the detection calibration curve (b) of Al 3+ ;

[0027] Figure 6 is the solid fluorescence spectrum diagram of the three-dimensional Tb-MOF compound in Application Example 4 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] ​Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Example 1

[0030] A three-dimensional Tb-MOF compound with the chemical formula {[H2N(CH3)2](H3O)[Tb(btec)(HCOO)(H2O)3]} n , where btec is the ligand pyromellitic acid, which is generated by the decomposition of the reactant ligand N,N-bis(3,5-dicarboxyphenyl)pyromellitimide during the synthesis reaction process. The three-dimensional Tb-MOF compound belongs to the orthorhombic crystal system and the Cmmm space group. The unit cell parameters are β = 90°,

[0031] Example 2

[0032] A preparation method of a three-dimensional Tb-MOF compound includes the following steps:

[0033] Add terbium nitrate hexahydrate (90.6 mg, 0.2 mmol) and N,N-bis(3,5-dicarboxyphenyl)pyromellitimide (54.4 mg, 0.1 mmol) into a 15 mL autoclave, successively add 5 mL of N,N-dimethylformamide (DMF) and 5 mL of 1 M HCl, heat to 130 °C, react for 72 h, then cool to room temperature, filter, wash with DMF three times, and dry at room temperature to obtain colorless flaky crystals, which are the three-dimensional Tb-MOF compound.

[0034] Based on the determination of the single crystal structure of a three-dimensional Tb-MOF compound, the process is as follows:

[0035] Tb-MOF single crystals with dimensions of 0.12×0.14×0.20 mm were selected and tested using a Bruker SMART APEX CCD X-ray single crystal diffractometer to collect single crystal data. The Shelxl-2018 program was used for data analysis and refinement. The crystal structure was solved by the direct method, and all non-hydrogen coordinates and anisotropic thermal parameters were refined using full-matrix least-squares methods. The geometric positions of hydrogen atoms on carbon were consistent with the theoretical riding model. Hydrogen atoms on coordinated water were determined by difference Fourier map analysis. The structure contained highly disordered solvent molecules, which were removed by using the SQUEEZE program in PLATON. The final molecular formula was obtained from the crystal structure combined with elemental analysis and thermogravimetric analysis. The crystallographic data and structure refinement parameters of compound Tb-MOF are summarized in Table 1.

[0036] Table 1 Crystal structure data and refinement parameters of a three-dimensional Tb-MOF compound

[0037]

[0038]

[0039] R1 = ∑||Fo| - |Fcs|| / ∑|Fo| wR2 = ∑[w(Fo 2 -Fc 2 ) 2 / ∑[w(Fo 2 ) 2 1 / 2

[0040] The crystal structure is shown in Figure 1 and 2 . Figure 1 (a) is a schematic diagram of the structure of compound Tb-MOF. Tb1 coordinates with nine O atoms to form a single-capped square antiprismatic structure ( Figure 1 (b)). Among them, O1 and O2, O1 i and O2 i are carboxyl oxygen atoms on two ligands btec, O6, O6 i , O7 come from O atoms on three coordinated water molecules, O5 and O5 i are O atoms on two formic acid molecules; the four carboxyl O atoms (O1, O1 i , O2, O2 i ) on two btec occupy four vertices of the bottom surface of the single-capped square antiprismatic structure; the two O atoms (O6, O6 i ) on two H2O and the two O atoms (O5, O5 i ​)Another plane is formed. The ligand btec has only one coordination mode in Tb-MOF, which is bidentate chelation; the carboxyl groups on the ligand have only one coordination mode, which is chelating coordination. The bond length range of Tb-O is 2.336(2)- The bond angle range of O-Tb-O is 50.65°(8)-153.00°(12), which is similar to the reported literature. In the structure of Tb-MOF, Tb1 chelates with four carboxyl groups from two different ligands btec to form a binuclear structure, as shown in Figure 1 (c); this binuclear structure is connected by two formic acid molecules to form a one-dimensional chain structure, as shown in Figure 2 (a). The one-dimensional chain structure is further connected into a three-dimensional supramolecular network structure through the hydrogen bond interaction between the uncoordinated carboxyl group on btec and the coordinated water, as shown in Figure 2 (b).

[0041] Example 3

[0042] A preparation method of a three-dimensional Tb-MOF compound includes the following steps:

[0043] Add terbium chloride hexahydrate (74.7 mg, 0.2 mmol) and N,N-bis(3,5-dicarboxyphenyl) pyromellitimide (54.4 mg, 0.1 mmol) into a 15 mL autoclave, successively add 4.5 mL N,N-dimethylformamide (DMF) and 5 mL 1M HCl, heat to 120 °C, react for 48 h, then cool to room temperature, filter, wash with DMF three times, and dry at room temperature to obtain colorless flaky crystals, which are the three-dimensional Tb-MOF compound.

[0044] Application Example 1

[0045] A fluorescence detection material uses the Tb-MOF compound prepared in Example 2 as the detection material for detecting 4-hydroxybenzaldehyde or metal ion Al 3+ .

[0046] Application Example 2

[0047] A fluorescence detection method for 4-hydroxybenzaldehyde includes the following steps:

[0048] (1) Take 3 mg of the three-dimensional Tb-MOF compound prepared in Example 2, grind it into powder, ultrasonically disperse it in 5 mL of DMF for 30 min to form a suspension, and prepare a 0.6 mg / mL Tb-MOF fluorescence probe solution.

[0049] (2) Take 1.5 mL of 0.6 mg / mL Tb-MOF fluorescent probe solution, and gradually add 0.01 M DMF solution of 4-hydroxybenzaldehyde to it, that is, add different microliters of 0.01 M DMF solution of 4-hydroxybenzaldehyde in batches. After each addition, measure the fluorescence spectrum once to obtain all the spectral graphs, as Figure 3 (a) shown. Calculate the ratio of the fluorescence intensity at 543 nm before and after adding the test solution to judge the concentration of 4-hydroxybenzaldehyde.

[0050] As Figure 3 shown, with the gradual addition of 4-hydroxybenzaldehyde, the fluorescence intensity of Tb-MOF at 543 nm gradually decreases until almost completely quenched; when the concentration of 4-hydroxybenzaldehyde is in the range of 0 - 0.1 mM, its concentration is linearly correlated with I0 / I, K = 29.44×10 3 M -1 , and the detection limit is 0.79 μM. When the concentration of 4-hydroxybenzaldehyde is in the range of 0.1 - 0.7 mM, its concentration is still linearly correlated with I0 / I, K = 97.10×10 3 M -1 . It shows that the concentration of 4-hydroxybenzaldehyde can be measured in a relatively wide range.

[0051] Investigate the detection of 4-hydroxybenzaldehyde by the three-dimensional Tb-MOF compound under the interference of other aldehydes. As Figure 4 shown, in the presence of other aldehyde aromatic compounds with similar structures (3-hydroxybenzaldehyde, 3-carboxybenzaldehyde, 4-carboxybenzaldehyde or 3-methylbenzaldehyde), 4-hydroxybenzaldehyde can still quench the fluorescence of the compound Tb-MOF, indicating its excellent anti-interference ability, which shows that Tb-MOF is a superior sensor for identifying 4-hydroxybenzaldehyde.

[0052] Application Example 3

[0053] A fluorescence detection method for Al 3+ , including the following steps:

[0054] (1) Take 3 mg of the three-dimensional Tb-MOF compound prepared in Example 2 ground into powder and ultrasonically disperse it in 5 mL of DMF for 30 min to form a suspension, and prepare a 0.6 mg / mL Tb-MOF fluorescent probe solution.

[0055] (2) Take 1.5 mL of 0.6 mg / mL Tb-MOF fluorescent probe solution, and gradually add 0.01 M DMF solution of Al 3+ ions to it, that is, add different microliters of 0.01 M DMF solution of Al 3+The DMF solution of the ions was added one by one, and the fluorescence spectrum was measured each time. All the spectral diagrams were obtained, as shown in Figure 5 (a). Calculate the ratio of the fluorescence intensities at 543 nm and 362 nm to judge the concentration of the metal ion Al 3+ .

[0056] As shown in Figure 5 , as the concentration of Al 3+ ions in the Tb-MOF fluorescence probe solution gradually increases, the intensity of Tb-MOF at 543 nm gradually decreases. At the same time, the fluorescence intensity at 362 nm gradually increases; and in the concentration range of 0 - 0.3 mM, the concentration of Al 3+ and I 543 / I 362 show a linear relationship. The linear regression equation is I 543 / I 362 =-22.43×[Al 3+ +16.16, and the detection limit is 0.67 μM. It shows that the Tb-MOF fluorescence probe prepared in the present invention has high sensitivity for the detection of Al 3+ ions.

[0057] Application Example 4

[0058] A luminescent material includes the three-dimensional Tb-MOF compound prepared in Example 2.

[0059] The crystal sample of the three-dimensional Tb-MOF compound prepared in Example 2 was ground thoroughly, and the solid luminescence test was carried out at room temperature. As shown in Figure 6 , when the excitation wavelength was set to 290 nm, the compound Tb-MOF showed four characteristic emission peaks of Tb 3+ , which were 488 nm ( 5 D4→ 7 F6), 543 nm ( 5 D4→ 7 F5), 584 nm ( 5 D4→ 7 F4) and 620 nm ( 5 D4→ 7 F6). Among them, the emission intensity at 543 nm ( 5 D4→ 7 F5) was the strongest. Therefore, Tb-MOF showed characteristic green luminescence under ultraviolet lamp irradiation. It can be seen that it has potential applications in the field of luminescent materials.

[0060] The above content is only an example and illustration of the present invention. Those skilled in the art to which the present technology pertains can make various modifications, supplements, or use similar methods of substitution to the described specific embodiments, as long as they do not deviate from the structure of the present invention or exceed the scope defined by this claims book, and shall fall within the protection scope of the present invention.

Claims

1. A three-dimensional Tb-MOF compound, characterized in that: Chemical formula: {[H2N(CH3)2](H3O)[Tb(btec)(HCOO)(H2O)3]}, where btec is the ligand benzene-1,2,4,5-tetracarboxylic acid. n ​ 2. The preparation method of the three-dimensional Tb-MOF compound according to claim 1, characterized in that It includes the following steps: reacting a terbium salt, ligand N,N-bis(3,5-dicarboxyphenyl) pyromellitimide, N,N-dimethylformamide, and dilute hydrochloric acid at 120-150 °C for 24-72 h, naturally cooling to room temperature after the reaction, filtering, washing, and drying to obtain the three-dimensional Tb-MOF compound.

3. The preparation method of a three-dimensional Tb-MOF compound according to claim 2, characterized in that: The terbium salt is at least one of terbium nitrate and terbium chloride.

4. The preparation method of a three-dimensional Tb-MOF compound according to claim 2, wherein: The molar ratio of the terbium salt, ligand N,N-bis(3,5-dicarboxyphenyl) pyromellitimide to N,N-dimethylformamide is (1.5-2.5):1:(520-780).

5. The preparation method of a three-dimensional Tb-MOF compound according to claim 2, characterized in that: The concentration of the dilute hydrochloric acid is 0.5-1.5 mol / L, and the molar ratio of the dilute hydrochloric acid to the terbium salt is 1:(15-40).

6. A fluorescent detection material, characterized in that: The material includes the three-dimensional Tb-MOF compound described in claim 1, and the fluorescence detection material is used to detect 4-hydroxybenzaldehyde or metal ion Al 3+ .

7. A fluorescence detection method, characterized in that, It includes the following steps: dispersing the crystalline material of the three-dimensional Tb-MOF compound described in claim 1 in an N,N-dimethylformamide solution to obtain a Tb-MOF suspension, adding the solution containing the analyte to the Tb-MOF suspension and shaking well, waiting for 30 - 240 s, and collecting the fluorescence emission spectrum of the mixture using a fluorescence spectrometer. The method is used to detect 4-hydroxybenzaldehyde or metal ion Al 3+ .

8. A fluorescence detection method according to claim 7, characterized in that: When the analyte is 4-hydroxybenzaldehyde, the ratio of the fluorescence intensities at 543 nm before and after adding the solution containing the analyte is calculated to determine the concentration of 4-hydroxybenzaldehyde; when the analyte is the metal ion Al 3+ ³⁺, the ratio of the fluorescence intensities at 543 nm and 362 nm is calculated to determine the concentration of Al 3+ ³⁺; the concentration of Al 3+ ³⁺ in the solution containing the analyte is 0 - 1.38 mmol / L; the concentration of 4-hydroxybenzaldehyde in the solution containing the analyte is 0 - 1.60 mmol / L.

9. A fluorescence detection method according to claim 7, characterized in that: The concentration of the Tb-MOF suspension is 0.5-1.0 mg / mL.

10. A luminescent material, characterized in that: It includes the three-dimensional Tb-MOF compound described in claim 1.

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