Sensing material based on Tb metal organic framework, preparation method and application thereof

Abstract

The invention provides a sensing material based on a Tb metal organic framework as well as a preparation method and application thereof, the sensing material takes Tb < 3 + > as a metal center and acid radical ions of 2, 3-quinoline dicarboxylic acid as organic ligands, and a two-dimensional network structure is formed through self-assembly. The preparation method comprises the following steps: adding 2, 3-quinoline dicarboxylic acid and Tb < 3 + >-containing metal salt into a mixed solvent, carrying out solvothermal reaction at 130-150 DEG C for 36-60 hours, and after the reaction is finished, cooling and separating to obtain the Tb-MOF sensing material. The Tb-MOF sensing material disclosed by the invention has excellent stability and wide pH adaptability, and shows remarkable fluorescence quenching response to Fe and Al, the detection limits of the Tb-MOF sensing material to Fe and Al respectively reach 8.60 nM and 9.27 nM, and the Tb-MOF sensing material is extremely high in sensitivity, so that high-selectivity and high-sensitivity rapid detection of Fe and Al is realized.

Description

Technical Field

[0001] This invention belongs to the field of chemical materials and sensing technology, and in particular relates to a sensing material based on Tb metal-organic framework, its preparation method and its application. Background Technology

[0002] With the continuous increase in emissions from mining, smelting, electroplating, chemical, and electronic waste, heavy metal pollution in water bodies is showing a trend towards complexity and diversification. Heavy metal pollutants are characterized by their non-degradability, ease of accumulation through the food chain, and toxic damage to multiple systems, including the nervous, liver, kidneys, and bones, making them a focal point of global environmental regulation and public health protection. Currently, countries have established increasingly stringent water quality concentration limits for more than twenty heavy metal ions, including lead, cadmium, chromium, nickel, copper, zinc, mercury, iron, and aluminum. Therefore, there is an urgent need for a low-cost detection technology that can simultaneously and rapidly screen multiple components in the field.

[0003] Traditionally, the detection of heavy metal ions has relied primarily on laboratory methods such as atomic absorption spectrometry, inductively coupled plasma mass spectrometry, and electrochemical anodic stripping spectroscopy. While these methods offer detection precision down to micrograms per liter, they are generally limited by factors such as bulky instruments, time-consuming sample pretreatment (e.g., acid digestion), the need for high-purity carrier gas, and the requirement for professional personnel. These limitations make them unsuitable for the rapid on-site detection needs of sudden pollution incidents. On the other hand, while on-site detection methods such as colorimetric strips and portable electrodes offer the advantage of ease of operation, they often face challenges such as severe interference from complex matrices, insufficient sensitivity, and the potential for cross-reactions between different valence states and coexisting ions. This leads to a high risk of misjudgment, and the detection limits often fail to meet the stringent requirements of micrograms per liter or even submicrograms per liter in drinking water standards.

[0004] In recent years, metal-organic frameworks (MOFs) have been regarded as ideal platforms for constructing high-performance heavy metal ion sensors due to their tunable pore structure, surface functionalization capabilities, and potential multi-site recognition. However, existing research mostly focuses on the recognition and detection of single ions, lacking a systematic solution that can simultaneously achieve good water stability, strong anti-interference ability, and effective signal amplification in real-world water samples. Therefore, developing MOF sensors with high selectivity and high sensitivity for use in complex heavy metal pollution scenarios has become an important research direction in the field of environmental analysis.

[0005] In particular, ferric ions (Fe³⁺) and aluminum ions (Al³⁺) are abundant in the Earth's crust and often coexist in large quantities in acidic mine drainage or eutrophic waters. Their hydrolysis behaviors are similar, leading to significant mutual interference. Fe³⁺ can catalyze the production of hydroxyl radicals, damaging the aquatic ecosystem. Excessive intake can also increase the risk of Parkinson's disease and cirrhosis; its drinking water limit is typically set at no more than 0.3 mg·L⁻¹. Al³⁺, on the other hand, has acute toxicity to fish gill tissue at micrograms per liter, and long-term accumulation is believed to be associated with Alzheimer's disease and osteoporosis. Its drinking water limit is more stringent, with many countries setting it at 0.2 mg·L⁻¹. Current detection methods, when dealing with systems where these two coexist, often require masking agents and complex acid-base adjustments to eliminate interference, resulting in cumbersome procedures and significant errors during on-site implementation.

[0006] Therefore, there is an urgent need to develop a novel metal-organic framework sensing material that can simultaneously distinguish and highly sensitively detect Fe³⁺ and Al³⁺ to fill the technological gap in rapid on-site monitoring of dual-target ions in complex pollution scenarios. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a sensing material based on Tb metal-organic framework, its preparation method and its application, to solve the problem that the detection methods in the prior art are difficult to achieve simple, highly selective and highly sensitive on-site rapid detection of coexisting Fe³⁺ and Al³⁺ in complex aquatic environments.

[0008] To achieve the above and other related objectives, the present invention provides a sensing material based on a Tb metal-organic framework, wherein the sensing material is based on Tb 3+ With a metal center and 2,3-quinolinedicarboxylic acid anion as an organic ligand, it forms a two-dimensional network structure through self-assembly.

[0009] Preferably, the sensing material belongs to the monoclinic crystal system and has a space group of C2. / C .

[0010] This invention also provides a method for preparing a sensing material based on a Tb metal-organic framework, the method comprising at least the following steps:

[0011] 2,3-quinolinedicarboxylic acid, containing Tb 3+ The metal salt is added to a mixed solvent and subjected to a solvothermal reaction at 130~150℃ for 36~60h. After the reaction is completed, the mixture is cooled and separated to obtain the Tb-MOF sensing material.

[0012] Preferably, the 2,3-quinolinedicarboxylic acid and the Tb-containing... 3+ The molar ratio of the metal salts is 1:1 to 1:6.

[0013] Preferably, the Tb-containing 3+ The metal salt is selected from one or a combination of terbium trichloride hexahydrate, terbium nitrate, terbium perchlorate, and terbium acetate.

[0014] Preferably, the mixed solvent is a mixture of an organic solvent and deionized water, wherein the volume ratio of the organic solvent to the deionized water is 1:3 to 1:6, and the organic solvent is selected from one or a combination of acetonitrile, N,N-dimethylformamide, methanol, and ethanol.

[0015] Preferably, the preparation method of the 2,3-quinolinedicarboxylic acid is as follows:

[0016] 1,2-Phenylacetamine and dimethyl terephthalate were mixed in a molar ratio of 1:1 to 1:1.5, a catalyst and an organic solvent were added, and the mixture was reacted at 90 to 120 °C for 10 to 36 h to obtain an intermediate.

[0017] The intermediate was subjected to alkaline hydrolysis at 90-120°C for 1-24 hours to obtain 2,3-quinolinedicarboxylic acid.

[0018] Preferably, the catalyst is selected from one or a combination of triethylamine, pyridine, N,N-diisopropylethylamine, and potassium carbonate.

[0019] Preferably, the organic solvent is selected from one or a combination of ethanol, isopropanol, acetonitrile, DMF, and DMSO.

[0020] This invention also provides an application of a Tb metal-organic framework-based sensing material, which is used as a fluorescence sensing element for detecting Fe. 3+ and / or Al 3+ The sensing material is either the Tb metal-organic framework-based sensing material described above, or a Tb metal-organic framework-based sensing material prepared using the above-described preparation method.

[0021] Preferably, the sensing material, as a fluorescent sensing element, has a detection limit of no more than 8.60 nM for Fe³⁺ and no more than 9.27 nM for Al³⁺.

[0022] As described above, the Tb-based metal-organic framework sensing material, its preparation method, and its application of the present invention have the following beneficial effects:

[0023] This invention successfully constructs a Tb-MOF sensing material with a specific monoclinic crystal system (C2 / c space group) and an sql topological network structure by self-assembling Tb³⁺ as the metal center and 2,3-quinolinedicarboxylic acid (H₂QDA) as the organic ligand. This Tb-MOF sensing material exhibits excellent water and thermal stability, enabling it to maintain structural integrity and functional stability in complex aquatic environments. It provides highly selective recognition sites, demonstrating significant fluorescence quenching responses to Fe³⁺ and Al³⁺, while showing weak responses to other common heavy metal ions, exhibiting excellent anti-interference capabilities. The detection limits for Fe³⁺ and Al³⁺ reach extremely high sensitivities of 8.60 nM and 9.27 nM, respectively, allowing it to withstand interference from multiple coexisting ions in complex aquatic environments and achieve highly selective and sensitive rapid detection of these two similar heavy metal ions, filling a technological gap in rapid on-site monitoring under complex pollution scenarios.

[0024] The raw materials for preparing the Tb-MOF sensing material in this invention are readily available. Synthesized via a mild and controllable solvothermal process, it boasts advantages such as high yield, low cost, and good reproducibility, making it suitable for large-scale production. The detection method based on this sensing material eliminates the need for complex sample pretreatment and large instruments; detection can be achieved simply by monitoring changes in fluorescence intensity. This extremely simple operation significantly reduces manpower and equipment costs, enabling low-cost and rapid screening of heavy metal pollutants in the field. Furthermore, the excellent stability and wide pH adaptability of this Tb-MOF sensing material ensure reliable detection capabilities in various actual water samples, systematically solving the bottleneck problem of traditional sensing technologies struggling to balance sensitivity, selectivity, environmental applicability, and on-site convenience. Attached Figure Description

[0025] Figure 1 The diagram shows the crystal structure of the Tb-MOF sensing material in Embodiment 1 of the present invention.

[0026] Figure 2 The diagram shows a 2D mesh structure of the Tb-MOF sensing material in Embodiment 1 of the present invention.

[0027] Figure 3 The image shown is a thermogravimetric analysis diagram of the Tb-MOF sensing material in Example 1 of this invention.

[0028] Figure 4 The image shows the fluorescence spectra of the Tb-MOF sensing material in different metal ions in Example 1 of this invention.

[0029] Figure 5 The image shows the fluorescence emission spectra of Tb-MOF in different concentrations of iron ions in Example 1 of this invention.

[0030] Figure 6 The image shows a dotted line graph of the fluorescence intensity of Tb-MOF in different concentrations of iron ions in Example 1 of this invention.

[0031] Figure 7 The image shows the fluorescence emission spectra of Tb-MOF in different concentrations of aluminum ions in Example 1 of this invention.

[0032] Figure 8 The image shows a dotted line graph of the fluorescence intensity of Tb-MOF in different concentrations of aluminum ions in Example 1 of this invention.

[0033] Figure 9 The image shows a bar chart of the fluorescence intensity of Tb-MOF under the coexistence conditions of iron ions and different heavy metal ions in Example 1 of this invention.

[0034] Figure 10 The image shows a bar chart of the fluorescence intensity of Tb-MOF under the coexistence conditions of aluminum ions and different heavy metal ions in Example 1 of this invention.

[0035] Figure 11 The image shows a dotted line graph of the fluorescence intensity of iron ions detected by Tb-MOF at different pH values ​​in Example 1 of this invention.

[0036] Figure 12 The image shows a dotted line graph of the fluorescence intensity of aluminum ions detected by Tb-MOF at different pH values ​​in Example 1 of this invention. Detailed Implementation

[0037] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0038] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0039] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0040] This invention provides a method for preparing a sensing material based on a Tb metal-organic framework, characterized in that the preparation method includes at least the following steps:

[0041] 2,3-quinolinedicarboxylic acid (H2QDA), containing Tb 3+ The metal salt is added to a mixed solvent and subjected to a solvothermal reaction at 130~150℃ for 36~60h. After the reaction is completed, the mixture is cooled and separated to obtain the Tb-MOF sensing material.

[0042] Specifically, the temperature of the solvothermal reaction can be any value within the range of 130℃, 135℃, 140℃, 145℃, 150℃, etc., and can be adjusted according to the actual situation. The time of the solvothermal reaction can be any value within the range of 36h, 42h, 48h, 54h, 60h, etc., and can be adjusted according to the actual situation.

[0043] As an example, the 2,3-quinolinedicarboxylic acid and the Tb-containing... 3+ The molar ratio of the metal salts is 1:1 to 1:6.

[0044] Specifically, 2,3-quinolinedicarboxylic acid and Tb-containing... 3+ The molar ratio of the metal salts can be any value within a range such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, etc., and can be adjusted according to actual needs.

[0045] As an example, the Tb-containing 3+ The metal salt is selected from one or a combination of terbium trichloride hexahydrate, terbium nitrate, terbium perchlorate, and terbium acetate.

[0046] As an example, the mixed solvent is a mixture of an organic solvent and deionized water, wherein the volume ratio of the organic solvent to the deionized water is 1:3 to 1:6, and the organic solvent is selected from one or a combination of acetonitrile, N,N-dimethylformamide, methanol, and ethanol.

[0047] Specifically, the mixed solvent can be one or a combination of acetonitrile and deionized water, N,N-dimethylformamide and deionized water, methanol and deionized water, and ethanol and deionized water; the volume ratio of the organic solvent to deionized water can be any value within the range of 1:3, 1:4, 1:5, 1:6, etc., and can be adjusted according to actual conditions.

[0048] As an example, the specific method for preparing the 2,3-quinolinedicarboxylic acid is as follows:

[0049] S11. Mix 1,2-phenylethylamine and dimethyl terephthalate in a molar ratio of 1:1 to 1:1.5, add a catalyst and an organic solvent, and react at 90 to 120°C for 10 to 36 hours to obtain an intermediate.

[0050] S12. The intermediate is subjected to alkaline hydrolysis at 90~120℃ for 1~24h to obtain 2,3-quinolinedicarboxylic acid.

[0051] Specifically, in step S11, the structural formula of 1,2-phenylethylamine is:

[0052] ;

[0053] The structural formula of dimethyl terephthalate is:

[0054] ;

[0055] The structural formula of the intermediate is:

[0056] .

[0057] In step S12, the structural formula of 2,3-quinolinedicarboxylic acid is:

[0058] .

[0059] Specifically, in step S11, the molar ratio of 1,2-phenylethylamine to dimethyl terephthalate can be any value within the range of 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, etc.; the reaction temperature can be any value within the range of 90℃, 100℃, 110℃, 120℃, etc.; and the reaction time can be any value within the range of 10h, 12h, 18h, 24h, 30h, 36h, etc., which can be adjusted according to the actual situation.

[0060] Specifically, the alkaline hydrolysis in step S12 involves hydrolyzing the intermediate in an alkaline solution. Preferably, the intermediate is mixed with NaOH, MeOH, and deionized water, and alkaline hydrolysis is carried out at 90~120℃ (e.g., 90℃, 100℃, 110℃, 120℃, etc.) for 1~24h (e.g., 1h, 6h, 12h, 18h, 24h, etc.). During alkaline hydrolysis, NaOH can be replaced with other alkaline solutions such as KOH; no specific limitation is made here. The addition of methanol (MeOH) during alkaline hydrolysis can adjust the polarity of the solution, and the methanol-water system is used to dissolve the reactants.

[0061] As an example, the catalyst is selected from one or a combination of triethylamine (N(CH2CH3)3), pyridine, N,N-diisopropylethylamine, and potassium carbonate.

[0062] As an example, the organic solvent is selected from one or a combination of ethanol (EtOH), isopropanol, acetonitrile, DMF, and DMSO.

[0063] The present invention also provides a sensing material based on a Tb metal-organic framework, wherein the sensing material is based on Tb 3+ With a metal center, the 2,3-quinolinedicarboxylic acid anion (BQDA) 2- () is an organic ligand that forms a two-dimensional network structure through self-assembly.

[0064] Specifically, the preparation of Tb-MOF-based sensing materials can be carried out using the above-mentioned methods for preparing Tb-MOF-based sensing materials, but it is not limited to these methods. Other preparation methods may also be used as needed.

[0065] In a specific embodiment of the present invention, the sensing material is prepared directly using the above-described method for preparing Tb-based metal-organic framework sensing materials. The chemical structural unit of this sensing material includes two Tb atoms. 3+ and 2,3-quinoline dicarboxylate ion (BQDA) 2- ).

[0066] As an example, the sensing material belongs to the monoclinic crystal system with space group C2. / C .

[0067] In addition, this invention also provides an application of a Tb metal-organic framework-based sensing material, which is used as a fluorescence sensing element for detecting Fe. 3+ and / or Al 3+ The sensing material is either the Tb metal-organic framework-based sensing material described above, or a Tb metal-organic framework-based sensing material prepared using the above-described preparation method.

[0068] Specifically, Tb-MOF sensing materials are used as fluorescent sensing elements to detect heavy metal ions. When Tb-MOF encounters heavy metal ions, its framework breaks down due to metal-coordination competition, releasing luminescent ligands. The difference in luminescence efficiency between the ligand and the MOF outputs a quantitative fluorescence on / off signal, thus completing the heavy metal detection. In a specific embodiment of this invention, Tb-MOF is used to detect Fe... 3+ and / or Al 3+ When this occurs, a fluorescence quenching effect takes place.

[0069] As an example, the sensing material, as a fluorescence sensing element, has a detection limit of no more than 8.60 nM for Fe³⁺ and no more than 9.27 nM for Al³⁺.

[0070] Specifically, Tb-MOF sensing materials are used as fluorescence sensing elements for the detection of Fe. 3+ and / or Al 3+ The specific steps include: using Tb-MOF sensing material as a fluorescence sensing element, contacting it with the water sample to be tested, so that the Tb-MOF sensing material reacts with Fe in the water sample. 3+ Alternatively, an Al³⁺ reaction can be performed; changes in the fluorescence signal of the reaction system are detected; finally, based on the changes in the fluorescence signal, the Fe content in the water sample is determined. 3+ The presence or absence of Al³⁺, or its concentration.

[0071] To better understand the Tb metal-organic framework-based sensing materials, preparation methods, and applications of this invention, specific embodiments are described below. It should be noted that these embodiments are merely descriptive and do not limit the invention in any way.

[0072] Example 1

[0073] This embodiment provides a method for preparing a sensing material based on a Tb metal-organic framework, characterized in that the preparation method includes at least the following steps:

[0074] S1. Preparation of 2,3-quinolinedicarboxylic acid;

[0075] S11. Mix 1,2-phenylethylamine (2 mmol) with dimethyl terephthalate (2 mmol), add 0.8 mL of catalyst (N(CH2CH3)3) and 20 mL of organic solvent (EtOH), place in a polytetrafluoroethylene reactor, and react at 90 °C for 36 h to obtain an intermediate;

[0076] S12. The intermediate was mixed with NaOH (25 mmol), MeOH (5.0 mL) and deionized water (25.0 mL) and subjected to alkaline hydrolysis at 90 °C for 12 h to obtain 2,3-quinolinedicarboxylic acid (H2QDA).

[0077] S2, 0.04 mmol of 2,3-quinolinedicarboxylic acid and 0.20 mmol of Tb-containing... 3+ The metal salt (TbCl3·6H2O) was added to a mixed solvent (composed of 12 mL deionized water and 2 mL acetonitrile), and the resulting mixture was placed in a polytetrafluoroethylene reactor and subjected to a solvothermal reaction at 140 °C for 48 h. After the reaction was completed, the mixture was cooled and separated to obtain the Tb-MOF sensing material.

[0078] The reaction flow chart for step S1 is as follows:

[0079]

[0080] This embodiment also provides a sensing material, which is prepared by the method for preparing a Tb-MOF-based sensing material in this embodiment. The chemical structural unit of this Tb-MOF sensing material includes Tb. 3+ and 2,3-quinoline dicarboxylate ion (BQDA) 2- ).

[0081] Performance testing:

[0082] 1. X-ray single-crystal diffraction analysis was performed on the Tb-MOF sensing material prepared in this embodiment using a DX-2700BH X-ray diffractometer. A schematic diagram of the crystal structure of the Tb-MOF sensing material was drawn after analysis (see...). Figure 1 ) and a schematic diagram of a 2D mesh structure (see Figure 2 ).

[0083] See Figure 1 This is a schematic diagram of the crystal structure of the Tb-MOF sensing material. The crystal belongs to the monoclinic C2 crystal system. / C Space group; each asymmetric element of a Tb-MOF has two Tb 3+ Four deprotonated H₂QDA atoms, each Tb³⁺ surrounded by eight oxygen atoms, originate from oxygen atoms in three different coordinated water molecules (O₁, O₄, O₁₁). The five oxygen atoms from the four deprotonated H₂QDA atoms (O₂, O₃, O₅, O₆, O₇) ultimately form a tetrahedron. See also... Figure 2 two adjacent Tb 3+ A 1D chain structure is formed by linking one carboxyl group of deprotonated H2QDA, and then linking the next two adjacent Tb groups with another carboxyl group. 3+This forms a 2D mesh structure; each adjacent pair of Tb 3+ Viewing each node as a "node" and the organic ligands connecting them as "linkage rods," analysis using software (TOPOS) reveals that each node steadily extends four linkage rods, connecting to the other four nodes. Tb-MOF represents a 4-joint SQL structure, with its topological notation being {4...}. 4 0.6 2}

[0084] 2. Thermogravimetric analysis was performed on the Tb-MOF sensing material prepared in this embodiment using a METTLER TG-DSC-1 thermogravimetric analyzer to investigate its stability at different temperatures. (See reference...) Figure 3 Thermogravimetric analysis curve of Tb-MOF, by Figure 3 It is known that the Tb-MOF sensing material experiences its first stage of weight loss at room temperature to 163℃, losing 6 coordinated water molecules, with a weight loss of approximately 7.33%. The stable range of the Tb-MOF sensing material is 163℃ to 492℃, within which it exhibits excellent thermal stability. When the temperature exceeds 492℃, the framework structure begins to collapse. This indicates that the Tb-MOF sensing material prepared in this embodiment can maintain basic structural stability before 163℃, demonstrating a certain degree of thermal stability.

[0085] 3. Ion selectivity of Tb-MOF sensing materials:

[0086] The optical properties of Tb-MOF sensing material in different heavy metal ions were determined. The specific steps included: dissolving 0.5 mg of Tb-MOF in 3.0 mL of water to prepare a bulk solution; then adding different heavy metal ions (Na+, Na+, and Sodium) at a concentration of 86.67 μM to the bulk solution. + Ag + K + Ni 2+ Fe 3+ Li + Al 3+ Ba 2+ Cu 2+ Zn 2+ Mg 2+ Cd 2+ Co 2+ Pb 2+ Ca 2 + Fe 2+ Cr 3+ Hg 2+ Fluorescence spectra of different added metal ions were obtained at an excitation wavelength of 320 nm, as shown in the figure. Figure 4 As shown.

[0087] See Figure 4 It can be seen that when Fe is added to the main solution 3+ Or Al 3+ Subsequently, the fluorescence significantly decreased, exhibiting a strong fluorescence quenching effect. However, after the addition of other metal ions, the fluorescence intensity remained essentially the same as that of Tb-MOF itself, showing no significant change. This indicates that Fe... 3+ The competitive mechanism with Tb in Tb-MOFs leads to the release of luminescent ligands, which weakens fluorescence. 3+ Similarly, this further demonstrates that Tb-MOF exhibits high selectivity for iron and aluminum ions; even in the presence of high concentrations of various interfering ions, Tb-MOF can still selectively target Fe ions. 3+ And Al 3+ It produces a unique and remarkable fluorescence response, while other ions produce almost no interfering signal.

[0088] 4. Continuous titration of Tb-MOF sensing materials:

[0089] 0.5 mg of Tb-MOF was dissolved in 3.0 mL of water to prepare the main solution, and different concentrations of Fe were added. 3+ At an excitation wavelength of 320 nm, the fluorescence emission spectrum was obtained, as follows: Figure 5 As shown; the fluorescence intensity at the fluorescence emission peak of 416 nm is used to correlate different concentrations of Fe. 3+ Plotting the graphs revealed the presence of different concentrations of Fe in Tb-MOF. 3+ The continuous titration spectrum fluorescence intensity dot plot, such as Figure 6 As shown.

[0090] Figure 5 The fluorescence response behavior of Tb-MOF sensing materials is shown under increasing Fe³⁺ concentrations (0 to 66.67 μM). Each curve represents the fluorescence intensity emitted by Tb-MOF at different wavelengths at a specific Fe³⁺ concentration. From top to bottom, the Fe³⁺ concentrations corresponding to the curves gradually increase from 0 µM (blank control) to 66.67 µM. Figure 5 It can be seen that Fe³⁺ ions can effectively quench the fluorescence of Tb-MOF; Figure 5 The small graph in the upper right corner shows that as the Fe³⁺ concentration (X-axis) increases, the quenching efficiency (Y-axis) increases monotonically and eventually approaches 1 (i.e., 100% quenching), indicating that there is a reliable and quantifiable relationship between Fe³⁺ concentration and signal changes, laying the foundation for quantitative detection.

[0091] Depend on Figure 6 It can be seen that Fe 3+Within a very low concentration range (0–30 µM), the fluorescence intensity ratio exhibits an excellent linear relationship with the Fe³⁺ concentration. The fitted linear equation is Y = -0.03539X - 0.0976, with a correlation coefficient R² = 0.9713, very close to 1, indicating a reliable linear relationship suitable for accurate quantification. Furthermore, this Tb-MOF sensing material is capable of detecting low concentrations of Fe. 3+ It exhibits extremely high sensitivity to Fe³⁺, with a calculated detection limit as low as 8.60 μM, which can meet the needs of trace and even ultra-trace detection.

[0092] 0.5 mg of Tb-MOF was dissolved in 3.0 mL of water to prepare the main solution, and different concentrations of Al were added. 3+ At an excitation wavelength of 320 nm, the fluorescence emission spectrum was obtained, as follows: Figure 7 As shown; the fluorescence intensity at the fluorescence emission peak of 416 nm is used to correlate different concentrations of Al. 3+ Plotting the graphs revealed the presence of different concentrations of Al in Tb-MOF. 3+ The continuous titration spectrum fluorescence intensity dot plot, such as Figure 8 As shown.

[0093] Figure 7 The changes in fluorescence emission spectra of Tb-MOF bulk solution after the addition of different concentrations of Al³⁺ ions are shown. The multiple curves in the figure correspond to the increasing Al³⁺ concentration from 0 μM to 86.67 μM from top to bottom. As the Al³⁺ ion concentration increases, the intensity of the fluorescence emission peak at 416 nm shows a regular and continuous decrease. This "fluorescence quenching" effect intuitively shows that the addition of Al³⁺ effectively and reversibly inhibits the fluorescence emission of Tb-MOF. Figure 7 The small graph in the upper right corner shows that the vertical axis represents quenching efficiency and the horizontal axis represents Al³⁺ concentration. The quenching efficiency increases monotonically with increasing Al³⁺ concentration and tends to saturate. This indicates that Tb-MOF has a wide dynamic range in response to Al³⁺ and achieves the maximum quenching effect at higher concentrations.

[0094] Figure 8 The main graph and the small graph in the upper right corner show the linear fitting results for different concentration ranges. As can be seen from the small graph, there is an excellent linear relationship between the fluorescence quenching degree of Tb-MOF and the Al³⁺ concentration in the range of 0-40 μM, which can be used for accurate quantitative analysis in this range. Combined with the main graph, it can be seen that Tb-MOF has a wide linear dynamic range for the detection of Al³⁺. The calculation shows that the detection limit of Tb-MOF sensing material for Al³⁺ is as low as 9.27 nM, which means it has high sensitivity.

[0095] 5. Ion competition of Tb-MOF sensing materials:

[0096] 0.5 mg of Tb-MOF sensing material was dissolved in 3.0 mL of water to prepare a bulk solution. Then, Fe was added to the bulk solution. 3+ and different heavy metal ions (Na) at a concentration of 86.67 μM + Ag + K + Ni 2+ Fe 3+ Li + Al 3+ Ba 2+ Cu 2+ Zn 2+ Mg 2+ Cd 2+ Co 2+ Pb 2+ Ca 2+ Fe 2+ Cr 3+ Hg 2+ Fluorescence emission spectra were obtained at an excitation wavelength λex of 320 nm; then, the fluorescence intensity at the fluorescence emission peak of 416 nm was plotted against different heavy metal ions to obtain the Fe... 3+ The results are shown in the histogram of fluorescence intensity with the addition of different heavy metal ions. Figure 9 As shown, it can be seen that Tb-MOF sensing materials are sensitive to Fe 3+ It has strong anti-interference ability and is not affected by other metal ions.

[0097] 0.5 mg of Tb-MOF sensing material was dissolved in 3.0 mL of water to prepare a bulk solution. Then, Al was added to the bulk solution. 3+ and different heavy metal ions (Na) with a concentration of 86.67 μM. + Ag + K + Ni 2+ Fe 3+ Li + Al 3+ Ba 2+ Cu 2 + Zn 2+ Mg 2+ Cd 2+ Co 2+ Pb 2+ Ca 2+ Fe 2+ Cr 3+ Hg 2+Fluorescence emission spectra were obtained at an excitation wavelength λex of 320 nm; then, the fluorescence intensity at the fluorescence emission peak of 416 nm was plotted against different heavy metal ions to obtain Al... 3+ The results are shown in the histogram of fluorescence intensity with the addition of different heavy metal ions. Figure 10 As shown, Tb-MOF sensing materials for Al 3+ It has strong anti-interference ability and is only affected by Fe. 3+ It is not affected by other metal ions, but is not affected by them.

[0098] 6. pH stability of Tb-MOF sensing materials:

[0099] A bulk solution was prepared by dissolving 0.5 mg of Tb-MOF in 3.0 mL of water, and fluorescence emission spectra were obtained at an excitation wavelength λex of 320 nm. A bulk solution was also prepared by dissolving 0.5 mg of Tb-MOF in 3.0 mL of water, and different concentrations of Fe were added. 3+ Fluorescence emission spectra were obtained at an excitation wavelength λex of 320 nm. Then, a dot plot of fluorescence intensity at the fluorescence emission peak of 416 nm was plotted to obtain a continuous titration fluorescence intensity dot plot of Tb-MOF with different concentrations of iron ions added, as shown below. Figure 11 As shown, it can be seen that Tb-MOF sensing materials have stable performance at pH 4 to 10.

[0100] A bulk solution was prepared by dissolving 0.5 mg of Tb-MOF in 3.0 mL of water, and fluorescence emission spectra were obtained at an excitation wavelength λex of 320 nm. The bulk solution was prepared by dissolving 0.5 mg of Tb-MOF in 3.0 mL of water, and different concentrations of Al were added. 3+ Fluorescence emission spectra were obtained at an excitation wavelength λex of 320 nm. Then, a dot plot of fluorescence intensity at the fluorescence emission peak of 416 nm was plotted to obtain a continuous titration fluorescence intensity dot plot of Tb-MOF with different concentrations of iron ions added, as shown below. Figure 11 As shown, it can be seen that Tb-MOF sensing materials have stable performance at pH 4 to 10.

[0101] Application Example 1

[0102] This application example provides an application of a Tb metal-organic framework-based sensing material, using the Tb-MOF sensing material prepared in Example 1 as a fluorescence sensing element for detecting Fe. 3+ and / or Al 3+ .

[0103] Specifically, Tb-MOF sensing materials are used as fluorescence sensing elements for the detection of Fe. 3+ and / or Al 3+The specific steps include:

[0104] Tb-MOF sensing material was used as a fluorescence sensing element and brought into contact with the water sample to be tested, allowing the Tb-MOF sensing material to react with Fe in the water sample. 3+ Alternatively, an Al³⁺ reaction can be performed; changes in the fluorescence signal of the reaction system are detected; finally, based on the changes in the fluorescence signal, the Fe content in the water sample is determined. 3+ The presence or absence of Al³⁺, or its concentration.

[0105] Specifically, according to Figure 9 and Figure 10 The results show that Tb-MOF sensing materials are effective for Fe 3+ It has strong anti-interference ability and is not affected by other metal ions. Tb-MOF sensing materials are sensitive to Al 3+ It has strong anti-interference ability and is only affected by Fe. 3+ It is not affected by other metal ions, i.e., Fe 3+ And Al 3+ Interference exists between them; Fe is present simultaneously in the water sample being tested. 3+ And Al 3+ At that time, according to Figure 4 It can be seen that Fe 3+ And Al 3+ The fluorescence attenuation of the two ions differs, and they can be distinguished by the different fluorescence attenuation intensities. Then, a standard curve is used for quantitative detection.

[0106] In summary, this invention successfully constructed a Tb-MOF sensing material with a specific monoclinic crystal system (C2 / c space group) and an sql topological network structure by self-assembling Tb³⁺ as the metal center and 2,3-quinolinedicarboxylic acid (H₂QDA) as the organic ligand. This Tb-MOF sensing material exhibits excellent water and thermal stability, enabling it to maintain structural integrity and functional stability in the complex environment of real water bodies. Furthermore, this Tb-MOF sensing material provides highly selective recognition sites, enabling it to... Fe³⁺ and Al³⁺ exhibit significant fluorescence quenching responses, while showing weak responses to other common heavy metal ions, demonstrating excellent anti-interference capabilities. The detection limits for Fe³⁺ and Al³⁺ reach extremely high sensitivities of 8.60 nM and 9.27 nM, respectively, enabling them to withstand interference from multiple coexisting ions in complex aquatic environments. This allows for the rapid detection of Fe³⁺ and Al³⁺, two heavy metal ions with similar characteristics, with high selectivity and sensitivity, filling the technological gap in rapid on-site monitoring under complex pollution scenarios. The raw materials for preparing the Tb-MOF sensing material in this invention are readily available. Synthesized via a mild and controllable solvothermal process, it boasts advantages such as high yield, low cost, and good reproducibility, making it suitable for large-scale production. The detection method based on this sensing material requires no complex sample pretreatment or large instruments; detection is achieved simply by monitoring changes in fluorescence intensity. This extremely simple operation significantly reduces labor and equipment costs, enabling low-cost and rapid screening of heavy metal pollutants in the field. Furthermore, the excellent stability and wide pH adaptability of this Tb-MOF sensing material ensure reliable detection capabilities in various actual water samples, systematically solving the bottleneck problem of traditional sensing technologies struggling to balance sensitivity, selectivity, environmental applicability, and on-site convenience. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial application value.

[0107] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A sensing material based on a Tb metal-organic framework, characterized in that, The sensing material is Tb 3+ With a metal center and 2,3-quinolinedicarboxylic acid anion as an organic ligand, it forms a two-dimensional network structure through self-assembly.

2. The sensing material based on a Tb metal-organic framework according to claim 1, characterized in that: The sensing material belongs to the monoclinic crystal system and has a space group of C2. / C .

3. A method for preparing a sensing material based on a Tb metal-organic framework, characterized in that: The preparation method includes at least the following steps: 2,3-quinolinedicarboxylic acid, containing Tb 3+ The metal salt is added to a mixed solvent and subjected to a solvothermal reaction at 130~150℃ for 36~60h. After the reaction is completed, the mixture is cooled and separated to obtain the Tb-MOF sensing material.

4. The method for preparing the sensing material based on the Tb metal-organic framework according to claim 3, characterized in that: The 2,3-quinolinedicarboxylic acid and the Tb-containing 3+ The molar ratio of the metal salts is 1:1 to 1:

6.

5. The method for preparing the sensing material based on the Tb metal-organic framework according to claim 3, characterized in that: The Tb-containing 3+ The metal salt is selected from one or a combination of terbium trichloride hexahydrate, terbium nitrate, terbium perchlorate, and terbium acetate.

6. The method for preparing the sensing material based on the Tb metal-organic framework according to claim 3, characterized in that: The mixed solvent is a mixture of an organic solvent and deionized water, wherein the volume ratio of the organic solvent to the deionized water is 1:3 to 1:6, and the organic solvent is selected from one or a combination of acetonitrile, N,N-dimethylformamide, methanol, and ethanol.

7. The method for preparing the sensing material based on the Tb metal-organic framework according to claim 3, characterized in that: The specific method for preparing the 2,3-quinolinedicarboxylic acid is as follows: 1,2-Phenylacetamine and dimethyl terephthalate were mixed in a molar ratio of 1:1 to 1:1.5, a catalyst and an organic solvent were added, and the mixture was reacted at 90 to 120 °C for 10 to 36 h to obtain an intermediate. The intermediate was subjected to alkaline hydrolysis at 90-120°C for 1-24 hours to obtain 2,3-quinolinedicarboxylic acid.

8. The method for preparing the sensing material based on the Tb metal-organic framework according to claim 7, characterized in that: Includes one or a combination of the following conditions: The catalyst is selected from one or a combination of triethylamine, pyridine, N,N-diisopropylethylamine, and potassium carbonate. The organic solvent is selected from one or a combination of ethanol, isopropanol, acetonitrile, DMF, and DMSO.

9. An application of a sensing material based on a Tb metal-organic framework, characterized in that: The sensing material is used as a fluorescence sensing element for detecting Fe. 3+ and / or Al 3+ The sensing material is the Tb metal-organic framework-based sensing material as described in claim 1 or 2, or the Tb metal-organic framework-based sensing material prepared by any of the preparation methods described in claims 3 to 8.

10. The application of the Tb metal-organic framework-based sensing material according to claim 9, characterized in that: The sensing material, as a fluorescent sensing element, has a detection limit of no more than 8.60 nM for Fe³⁺ and no more than 9.27 nM for Al³⁺.

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