Terbium-based three-dimensional metal organic framework material as well as preparation method and application thereof

Abstract

The invention discloses a terbium-based three-dimensional metal organic framework material as well as a preparation method and application thereof, and belongs to the technical field of new materials. The preparation method comprises the following steps: mixing H2tdc, terbium salt and 4, 4 '-Dm-2, 2'-bpy in a solvent, and carrying out a thermal reaction to obtain the terbium-doped H2tdc-terbium-doped 4, 4 '-Dm-2, 2'-bpy. The three-dimensional lanthanide series metal organic framework material ZJS-Tb is successfully prepared by adopting a solvothermal method, the material has an excellent selective fluorescence quenching effect (the quenching constant is 2.43 * 10 < 5 > M <-1 >) and a low detection limit (1.06 mu mol / L) on p-NP, has excellent cycling stability, and can keep stable fluorescence performance after continuous five times of cycling; the preparation method is simple, mild in condition and high in preparation efficiency, provides a novel fluorescent probe material and a preparation method for detecting p-NP in a solution based on a lanthanide metal organic framework material, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and in particular to a terbium-based three-dimensional metal-organic framework material and a preparation method and application thereof. Background Art

[0002] With the development of society and the advancement of science and technology, chemical products such as dyes, medicines, and pesticides have been widely used, causing serious environmental pollution. In the past few decades, many technologies for detecting chemical pollutants have been developed. In contrast, fluorescent probes have the advantages of simple operation, high sensitivity, and recyclability, which are not available in other traditional methods. p -NP) is a typical highly destructive compound. Due to its strong toxicity and carcinogenicity, it is easily enriched in soil and water, destroying the ecological balance, causing cancer, liver damage and other diseases, and endangering human health. Therefore, it is necessary to design a sensitive, efficient and economical detection method to detect p -NP.

[0003] Current testing p There are many methods for detecting NPs, such as atomic absorption spectroscopy, liquid or gas chromatography, and electrochemical methods. Although these methods are effective, they require expensive equipment and take a long time to process. Therefore, how to design a method with high sensitivity and good selectivity? p NP detection methods remain a hot topic and a challenge in current research. However, in various applications, fluorescence detection based on chemical sensors is the best choice for rapid identification and detection of ions and small molecules. Compared with traditional detection methods, fluorescence detection has the advantages of high sensitivity, good selectivity, and strong practicality.

[0004] However, most of the reported p The probe molecules for NP detection are all transition metal complexes, which have poor detection effects. Rare earth ions have high coordination numbers and are ideal for the preparation of p Ln-MOFs for NP detection still faces major challenges. How to prepare Ln-MOFs with high sensitivity and low detection limit is the key to solving the existing detection problems. p -One of the key issues is the high cost and time of NP detection methods, as well as the poor detection effect of the probe molecules used in fluorescence detection. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a terbium-based three-dimensional metal organic framework material and its preparation method and application, so as to solve the existing detection p -NP detection methods are expensive and time-consuming, and the probe molecules used in fluorescence detection have poor detection effects.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: A first aspect of the present invention provides a method for preparing a terbium-based three-dimensional metal-organic framework material, comprising the following steps: The product is prepared by mixing 2,5-thiophenedicarboxylic acid (H2tdc), terbium salt and 4,4'-dimethyl-2,2'-bipyridine (4,4'-Dm-2,2'-bpy) in a solvent and subjecting them to a thermal reaction.

[0007] The beneficial effects of the present invention are as follows: the present invention provides a method for preparing terbium-based three-dimensional metal-organic framework materials by a solvent thermal method, the preparation method is simple, the conditions are mild, the preparation yield is high, and the prepared terbium-based three-dimensional metal-organic framework materials are p -NP has excellent selective fluorescence quenching effect (quenching constant 2.43×10 5 M -1 ) and a low detection limit (1.06 μmol / L), with excellent cycling stability, able to maintain stable fluorescence performance after five consecutive cycles.

[0008] Further, the terbium salt includes Tb(NO3)3·6H2O.

[0009] Preferably, the terbium salt is Tb(NO3)3·6H2O.

[0010] Furthermore, the molar ratio of H2tdc, terbium salt and 4,4'-Dm-2,2'-bpy is 1:(1-3):(1-3).

[0011] Preferably, the molar ratio of H2tdc, terbium salt and 4,4'-Dm-2,2'-bpy is 1:1:1.

[0012] Furthermore, the solvent is a mixed solvent consisting of DMF and deionized water.

[0013] Furthermore, the volume ratio of DMF to deionized water in the mixed solvent is 1:(5-10).

[0014] Preferably, the volume ratio of DMF to deionized water in the mixed solvent is 1:7.

[0015] Furthermore, the mass volume ratio of H2tdc to the solvent is 5-10 mg:5-10 mL.

[0016] Preferably, the mass volume ratio of H2tdc to the solvent is 8.7 mg:8 mL.

[0017] Furthermore, the thermal reaction temperature is 80-120° C., and the time is 50-100 h.

[0018] Preferably, the thermal reaction temperature is 100° C. and the time is 72 h.

[0019] Furthermore, the mixed reaction system is ultrasonically treated for 1-10 min before the thermal reaction.

[0020] Preferably, the mixed reaction system is ultrasonically treated for 5 min before the thermal reaction.

[0021] The second aspect of the present invention provides a terbium-based three-dimensional metal-organic framework material, which is prepared using the above-mentioned preparation method.

[0022] The third aspect of the present invention provides the use of the above-mentioned terbium-based three-dimensional metal-organic framework material in the detection of p-nitrophenol.

[0023] The present invention has the following beneficial effects: The present invention successfully prepared a three-dimensional lanthanide metal organic framework material [Tb2(tdc 2- )3(4,4'-Dm-2,2'-bpy)2](ZJS-Tb), this material is p -NP has excellent selective fluorescence quenching effect (quenching constant 2.43×10 5 M -1 ) and a low detection limit (1.06 μmol / L), with excellent cyclic stability and the ability to maintain stable fluorescence performance after five consecutive cycles; the preparation method is simple, the conditions are mild, and the preparation efficiency is high, which provides a basis for the detection of lanthanide metal-organic frameworks in solution. p -NP provides a new fluorescent probe material and preparation method with broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the infrared spectrum of ZJS-Tb; Figure 2 is the PXRD pattern of ZJS-Tb; Figure 3 This is a photo of ZJS-Tb under an optical microscope; Figure 4 Figure 3 is the configuration and coordination relationship diagram of ZJS-Tb, where (a) is the coordination environment of Tb in ZJS-Tb, symmetric code: #1: x+1 / 2, -y+1 / 2, z+1 / 2; #2: x+1 / 2, y, -z; #3: x, -y+1 / 2, -z+1 / 2; (b) is the binuclear cluster structure of Tb(III) in the ZJS-Tb structure; (c) is the coordination mode of H2tdc and 4,4'-Dm-2,2'-bpy; (d) is the one-dimensional pore and three-dimensional framework structure in ZJS-Tb; (e) is the simplified topological structure of ZJS-Tb along the b-axis; Figure 5Topology connection relationship diagram of ZJS-Tb, wherein (a) is a μ2-ligand used as a 6-c node; (b) is a typical 6-connected dinuclear secondary building unit; Figure 6 TG diagram of ZJS-Tb; Figure 7 Solid-state fluorescence performance characterization results of ZJS-Tb, wherein (a) is an excitation spectrum and an emission spectrum of ZJS-Tb; (b) is a CIE spectrum of ZJS-Tb, (c) is a Tauc curve diagram of the band gap of ZJS-Tb; Figure 8 Detection results of ZJS-Tb p -NP capability, wherein (a) is a fluorescence spectrum diagram of ZJS-Tb in different NAC solutions; (b) is a fluorescence spectrum diagram of ZJS-Tb in different concentrations p -NP; (c) is a linear and nonlinear relationship of ZJS-Tb in different concentrations p -NP solutions; (d) is an anti-interference experiment result of ZJS-Tb on p -NP; Figure 9 Cycling experiment results of ZJS-Tb. DETAILED DESCRIPTION

[0025] The principles and characteristics of the present application are described below in conjunction with the accompanying drawings, and the examples are only used to explain the present application and are not used to limit the scope of the present application. If no specific conditions are specified in the examples, conventional conditions or manufacturer recommended conditions are used. If no manufacturer of the reagents or instruments is specified, it is a conventional product that can be purchased on the market.

[0026] Example 1: A preparation method of a terbium-based three-dimensional metal organic framework material, comprising the following steps: First, a mixture of H2tdc (0.05 mmol, 8.70 mg), Tb(NO3)3·6H2O (0.05 mmol, 26.50 mg), 4,4'-Dm-2,2'-bpy (0.05 mmol, 9.20 mg), DMF (1 mL) and deionized water (7 mL) is added to a 25 mL high-pressure reaction kettle; then the mixture is ultrasonically treated for 5 min, and then reacted at 100 ℃ for 72 h; finally, it is naturally cooled to room temperature to obtain purple-red rod-shaped crystals, which are washed with deionized water, filtered and naturally air-dried to collect the product [Tb2(tdc 2- )3(4,4'-Dm-2,2'-bpy)2], named as ZJS-Tb. Yield: 42% (based on H2tdc).

[0027] The results of elemental analysis are: C 42 H 30 Tb2N4O 12 S3, found (calcd), %: C, 42.15 (42.12); H, 2.53 (2.52); N, 4.68 (4.67).

[0028] Infrared spectroscopy Figure 1 As shown, FT-IR (cm -1 , KBr): 3412(s), 1645(s), 1616(s), 1547(w), 1525(s), 1488(w), 1376(s), 1235(w), 1128 (m), 1014(s), 921(s), 830(s), 801(m), 774(s), 678(s), 543(s), 516(s), 479(s), 421(s).

[0029] Example 2: A method for preparing a terbium-based three-dimensional metal-organic framework material comprises the following steps: A mixture of H2tdc (0.05 mmol, 8.70 mg), Tb(NO3)3·6H2O (0.05 mmol, 26.50 mg), 4,4'-Dm-2,2'-bpy (0.05 mmol, 9.20 mg), DMF (1 mL) and deionized water (10 mL) was first added to a 25 mL autoclave. The mixture was then ultrasonicated for 5 min and reacted at 120 °C for 50 h. Finally, it was naturally cooled to room temperature to obtain purple-red rod-shaped crystals, which were washed with deionized water, filtered, and naturally dried to collect the product.

[0030] Example 3: A method for preparing a terbium-based three-dimensional metal-organic framework material comprises the following steps: A mixture of H2tdc (0.05 mmol, 8.70 mg), Tb(NO3)3·6H2O (0.05 mmol, 26.50 mg), 4,4'-Dm-2,2'-bpy (0.05 mmol, 9.20 mg), DMF (1 mL) and deionized water (5 mL) was first added to a 25 mL autoclave. The mixture was then ultrasonicated for 5 min and reacted at 80 °C for 100 h. Finally, it was naturally cooled to room temperature to obtain purple-red rod-shaped crystals, which were washed with deionized water, filtered and naturally dried to collect the product.

[0031] Experimental Example 1: Structural Characterization 1. Characterization methods Powder X-ray diffraction (PXRD) data were collected using a Rigaku Ultima IV X-ray diffractometer equipped with a Mo-Kα radiation source. The product morphology was observed using an optical microscope. The configuration, coordination relationship, and structural topology of ZJS-Tb were analyzed using SHAPE V2.0 and TOPOS4.0 software.

[0032] 2. Characterization Results The structural characterization results are as follows Figure 2-Figure 4 As shown in Tables 1-3.

[0033] Table 1 Crystallographic data and structure refinement details of ZJS-Tb

[0034] Table 2 Geometric configuration of Tb(III) in ZJS-Tb analyzed by SHAPE software

[0035] Table 3 Some bond lengths and bond angles of ZJS-Tb

[0036] The PXRD pattern of ZJS-Tb is as follows Figure 2 As shown in the figure, the spectrum shows strong diffraction peaks at 2θ = 7.11°, 9.64°, 17.50°, 18.13° and 18.85°, corresponding to the (110), (300), (202), (102) and (321) crystal planes, respectively. The experimental results are highly consistent with the simulation data, fully confirming the phase purity and structural integrity of ZJS-Tb. The single crystal X-ray diffraction results show (crystal information is shown in Table 1) that ZJS-Tb belongs to the orthorhombic system. Pnna Space group.

[0037] Figure 3 The optical microscope photo in the figure shows that ZJS-Tb has a purple rod-shaped crystal structure.

[0038] like Figure 4 As shown in Figure (a), the asymmetric unit of ZJS-Tb contains 1 Tb(III) atom, 1.5 tdc 2- ligand and one 4,4'-Dm-2,2'-bpy ligand to form an octa-coordinate structure; Figure 4 As shown in Figure (b), two Tb1 atoms pass through four tdc 2- The four bridging carboxyl groups of the ligand form a binuclear [Tb2(COO)4] cluster unit. According to the analysis results of SHAPE software in Table 2, each Tb(III) atomic center has a triangular dodecahedron configuration. Figure 4As shown in Figure (c), tdc 2- The ligand exhibits two coordination modes, one of which is to bind to four different Tb(III) atoms through monodentate coordination via four carboxylic acid O atoms, and the other is to connect two Tb(III) atoms through two carboxylic acid groups in a chelating manner, thereby forming a three-dimensional network structure with the 4,4'-Dm-2,2'-bpy ligand. Among them, the Tb-N bond length range is 2.553(3)-2.570(3) Å, and the Tb-O bond length range is 2.289(3)-2.500(2) Å, as shown in Table 3. In the ZJS-Tb structure, the eight Tb(III) dodecahedral nodes are bridged by organic ligands to form a one-dimensional columnar open channel, as shown in Figure 3. Figure 4 As shown in Figure (d). From a topological point of view, tdc 2- The ligand and dinuclear unit act as 2-connected nodes and 6-connected nodes, respectively, as Figure 5 The TOPOS 4.0 software analysis results are shown in Figure 4 As shown in Figure (e), the results show that the topological type of the structure is 2,6T1 and the Schlafli symbol is {8 12 12 3}{8}3.

[0039] Test Example 2: Thermal Performance Characterization 1. Characterization methods Thermogravimetric analysis (TGA) was performed using a German NETZSCH STA 449 F5 analyzer in a N2 atmosphere with a temperature range of 30–800 °C and a heating rate of 10 °C / min.

[0040] 2. Characterization Results TGA characterization results are as follows Figure 6 The results show that ZJS-Tb remains stable from room temperature to 386°C. Above this temperature, its organic framework gradually collapses and results in significant mass loss. At 800°C, the residual mass of ZJS-Tb is 48.01%, indicating that ZJS-Tb does not completely decompose under N2 conditions and the residual amount is greater than the theoretical value, indicating excellent thermal stability.

[0041] Test Example 3: Solid-state fluorescence performance characterization 1. Characterization methods The fluorescence spectrum of ZJS-Tb was characterized by RF-5310PC fluorescence spectrophotometer, and the UV-visible diffuse reflectance spectrum of ZJS-Tb was measured at room temperature.

[0042] 2. Characterization Results The characterization results are shown in Figure 7. Figure 7As shown in Figure (a), the excitation spectrum of ZJS-Tb presents a broad band spectrum in the range of 300-336 nm, with the maximum excitation wavelength at 232 nm. Under the excitation wavelength of 323 nm, four sharp emission peaks of ZJS-Tb are observed at 488 nm, 543 nm, 585 nm and 620 nm, corresponding to 5 D4→ 7 F J ( J = 6, 5, 4, 3) transitions. The fluorescence emission data of ZJS-Tb were converted into color coordinates to clearly show its luminescence. The CIE coordinates of ZJS-Tb are (0.3580, 0.4711), indicating that ZJS-Tb is a potential green light material (such as Figure 7 (as shown in Figure (b)).

[0043] The spectral band gap analysis and calculation are performed using the relationship proposed by Tauc: ; Where, α is the absorbance, hν represents the photon energy, A is a constant, n Represents the transition type ( n = 1 / 2 indicates a direct transition, n = 2 for indirect transition). Using ( αhν ) 2 right hν Draw a graph and extend the straight line part outward to the x The intersection point is the bandgap width of ZJS-Tb. E g .like Figure 7 As shown in Figure (c), the ZJS-Tb is calculated E g The zeta potential is 3.70 eV, indicating that it has application potential as a semiconductor material.

[0044] Test Example 4: Detection p -Characterization of NP capabilities 1. Detection Effects of Different NACs After 20 mg of ZJS-Tb was fully ground, 50 mL of deionized water was added, and the mixture was ultrasonicated for 5 min. Then, 1.0×10 -3 mol / L of different NACs (including o-nitroaniline ( o -NA), p-nitroaniline ( p -NA), o-nitrophenol ( o -NP) and p-nitrophenol ( p-NP)) solution, and its fluorescence spectrum was measured by FLS1000 steady-state transient fluorescence spectrometer.

[0045] The experimental results are as follows Figure 8 As shown in Figure (a), different NACs have different effects on the fluorescence intensity of ZJS-Tb. p -NP significantly reduced the fluorescence intensity of ZJS-Tb, while the fluorescence quenching effect caused by other NACs was negligible. The results showed that ZJS-Tb can specifically detect p -NP.

[0046] 2. Quenching efficiency 1.0×10 -3 mol / L p -NP solution was gradually dropped into 0.4 mg / mL ZJS-Tb suspension, and its fluorescence spectrum was measured at room temperature.

[0047] The experimental results are as follows Figure 8 As shown in Figure (b), the results show that p -NP showed a significant quenching effect on ZJS-Tb. p When the -NP volume was 120 μL, the quenching efficiency reached 98.82%.

[0048] For quantitative analysis p The fluorescence quenching efficiency of NPs was established. p The linear relationship between the NP concentration and the luminescence intensity at 543 nm, as Figure 8 As shown in Figure (c), the curve conforms to the Stern-Volmer (SV) equation: ; in, I 0 and I To add p -Luminescence intensity before and after NP, K SV represents the quenching constant (M -1 ), [M] represents p -Molar concentration of NPs.

[0049] At low concentrations, p There is a significant linear relationship between the NP concentration and the quenching constant ( R 2 = 0.9924), which conforms to the linear relationship: y = 2.43 × 10 5 x + 0.30, calculated ZJS-Tb K SVThe value is 2.43 × 10 5 M -1 In addition to the SV equation, the limit of detection (LOD) is another important parameter for evaluating the sensitivity of luminescence sensors. LOD is calculated by 3σ / K SV The calculation results show that the LOD value of ZJS-Tb is 1.06 μmol / L, indicating that ZJS-Tb can effectively detect low concentrations of p -NP. With p -NP solution concentration increases, the quenching constant is p -NP concentration gradually deviates from the linear relationship and conforms to the nonlinear equation in the entire concentration range: y = 0.65 × exp(1.11 × 10 5 x ) + 1.26( R 2 = 0.9908). The results show that the ZJS-Tb prepared in the present invention has a fluorescence quenching efficiency comparable to that of sensors disclosed in existing literature, as shown in Table 4. Among them, samples 1-5 are from the following literatures: Sample 1: C. Sen, S. Devi, Niharika, N. Bhagat, HN Sheikh, Dual ligandbased 3D Eu(III) MOF as a multifunctional sensor for trace amounts of NACs,Cr 3+ and Hg 2+ in aqueous medium: synthesis, crystal structure and latent fingerprint detection, CrystEngComm. 26 (2024) 5013-5029. Sample 2: C. Sen, S. Devi, Niharika, N. Bhagat, HN Sheikh, A 3Dphotoluminescent Eu(III)-MOF sensor supported by a tetracarboxylate ligand for the sensitive and selective detection of Cd 2+ and o-nitrophenol, New. J.Chem. 48 (2024) 15136-15148. 样品3:Y. Yang, Z.H. Chen, C.Y. Fu, S. Kumar, W. Shi, F.Y. Sun, X.M.Yang, P. Ren, Selective and rapid detection of 4-nitrophenol in river andtreated industrial wastewater by a luminescent lanthanide metal-organicframework sensor, Inorg. Chem. 62 (2023) 19565-19572. 样品4:Y. Liu, J.L. Li, N. Zhang, Y. Zhao, Q.L. Guan, Y.H. Xing, F.Y.Bai, Tb-TATAB crystalline organic framework material based on triazinetricarboxylic acid ligand: photophysical properties and fluorescence sensingapplications, CrystEngComm. 27 (2025) 1939-1949. 样品5:C. Sen, R. Singh, S. Devi, Niharika, R. Singhaal, S.C. Sahoo,H.N. Sheikh, Design and synthesis of 2D coordination polymers fromisophthalic and adipic acids: exploring Tb-based luminescent sensors for Cr 3+ ,Fe 3+ and p-NA, New. J. Chem. 49 (2025) 2350-2364. Sample 6: D. Ahlawat, S. Pachisia, Aashish, R. Gupta, Lanthanide-basedmetal-organic frameworks offering hydrogen bonding cavities: Luminescentcharacteristics and sensing applications, Chem-Asian. J. 20 (2025)e202401213. Table 4 ZJS-Tb K SV Comparison of LOD values ​​with those of previously reported complexes

[0050] 3. Selective Detection Capabilities Validation of ZJS-Tb specific detection by competition experiments p -NP capacity. 1×10 -2 mol / L potential NACs( o -NA, p -NA and o -NP) solution, to which 1×10 -3 mol / L p -NP, and measure the fluorescence intensity.

[0051] The experimental results are as follows Figure 8 As shown in Figure (d), add p -NP, the fluorescence intensity was significantly quenched, and the added NACs had little effect on the fluorescence intensity of ZJS-Tb. p -NP has excellent selective detection ability.

[0052] 4. Cycle performance To evaluate the recyclability of ZJS-TB, ZJS-TB was p -NP solution for 12 h and then collected by centrifugation, and its fluorescence spectrum was measured.

[0053] The experimental results are as follows Figure 9 As shown in Figure 2, after five cycles of testing, there was almost no significant decrease in fluorescence intensity compared to the unsoaked sample. p -NP detection has excellent stability and cycling performance.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a terbium-based three-dimensional metal-organic framework material, characterized in that: The following steps are involved: The product is prepared by mixing H2tdc, terbium salt and 4,4'-Dm-2,2'-bpy in a solvent and subjecting them to thermal reaction.

2. The method for preparing a terbium-based three-dimensional metal-organic framework material according to claim 1, characterized in that: The terbium salt includes Tb(NO3)3·6H2O.

3. The method for preparing a terbium-based three-dimensional metal-organic framework material according to claim 1, wherein: The molar ratio of H2tdc, terbium salt and 4,4'-Dm-2,2'-bpy is 1:(1-3):(1-3).

4. The method for preparing a terbium-based three-dimensional metal-organic framework material according to claim 1, wherein: The solvent is a mixed solvent consisting of DMF and deionized water.

5. The method for preparing a terbium-based three-dimensional metal-organic framework material according to claim 4, characterized in that: The volume ratio of DMF to deionized water in the mixed solvent is 1:(5-10).

6. The method for preparing a terbium-based three-dimensional metal-organic framework material according to claim 1, characterized in that: The mass volume ratio of the H2tdc and the solvent is 5-10 mg:5-10 mL.

7. The method for preparing a terbium-based three-dimensional metal-organic framework material according to claim 1, characterized in that: The temperature of the thermal reaction is 80-120° C. and the time is 50-100 h.

8. The method for preparing a terbium-based three-dimensional metal-organic framework material according to claim 1, characterized in that: The mixed reaction system was ultrasonically treated for 1-10 min before the thermal reaction.

9. A terbium-based three-dimensional metal-organic framework material, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. Use of the terbium-based three-dimensional metal-organic framework material according to claim 9 in the detection of p-nitrophenol.

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