L-histidine functionalized ZrTb-His-MOG as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of chemical analysis, and relates to L-histidine functionalized ZrTb-His-MOG as well as a preparation method and application thereof. The fluorescent material is formed by coordination self-assembly of Zr < 4 + >, Tb < 3 + > and bifunctional ligands L-His and BTC through a solvothermal method. A 366 nm signal is generated by Zr < 4 + >-L-His ligand-metal charge transfer, and a 546 nm signal output by a BTC-Tb < 3 + > antenna effect is combined to construct a double-signal ratio detection mechanism for quantitative detection of Hg < 2 + >; and the adsorption quantity is measured through an ultraviolet absorption spectrum. The material shows high selectivity, wide linear detection range and strong adsorption capacity to Hg < 2 + >, the reliability is verified through sample adding standard recovery and adsorption saturation capacity tests, the material is suitable for rapid detection and efficient adsorption of Hg < 2 + > in complex scenes such as industrial wastewater, and the problems that a traditional material is low in detection precision and poor in adsorption performance are effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of chemical analysis technology, specifically relating to an L-histidine-functionalized ZrTb-His-MOG, its preparation method, and its application. Background Technology

[0002] Mercury ions (Hg) 2+ As a highly toxic heavy metal pollutant, ions are widely found in various industrial wastewaters, agricultural soils, and many foods. These ions exhibit strong bioaccumulation and persistence, accumulating continuously through the food chain. Once in the human body, they primarily damage the central nervous system, kidneys, and liver, causing irreversible health hazards. Therefore, developing multifunctional materials capable of both efficient identification and rapid adsorption and removal is of urgent practical significance for environmental monitoring, food safety, and human health protection.

[0003] Currently, for Hg 2+ Conventional detection methods mainly include large-scale instrumental analysis methods such as atomic absorption spectrometry and atomic fluorescence spectrometry. While these methods offer high detection accuracy, they typically rely on complex and expensive equipment, specialized operation, and long analysis cycles, making them unsuitable for rapid on-site detection and real-time monitoring. Regarding adsorption removal, traditional adsorbents such as activated carbon, zeolite, and resins, although effective for Hg removal... 2+ While possessing a certain adsorption capacity, they generally suffer from poor selectivity, limited adsorption capacity, and an inability to reflect the adsorption process and pollution status in real time.

[0004] In recent years, fluorescence-based materials and technologies have attracted widespread attention in the field of heavy metal ion detection due to their advantages of high sensitivity, rapid response, ease of operation, and visualization. Among them, metal-organic gels (MOGs), as an emerging porous soft material, have shown great potential as both fluorescence sensors and adsorbents due to their tunable chemical structure, abundant active sites, diverse pore size distribution, and flexible fluorescence properties. However, most reported MOG-based materials currently have relatively limited functions, often focusing only on sensing or adsorption, making it difficult to achieve the detection of Hg. 2+ The integrated treatment of "real-time detection and simultaneous removal" is proposed. However, some materials with dual functions often suffer from insufficient detection sensitivity and high detection limits due to limitations in their fluorescence response mechanisms, making them unsuitable for effectively detecting trace amounts of Hg in actual samples. 2+ The need for precise testing. Summary of the Invention

[0005] The purpose of this invention is to provide an L-histidine-functionalized ZrTb-His-MOG, its preparation method, and its applications, thereby overcoming the shortcomings of existing technologies and selecting rare earth metal ions Tb with unique ff transition fluorescence characteristics.3+ With Zr 4+ As a metal node, introducing Hg 2+ ZrTb-His-MOG materials were constructed via self-assembly using the dual ligands histidine (L-His) and trimesic acid (BTC), which possess specific recognition capabilities. This composite material, based on a ratiometric fluorescence sensing mode, can achieve not only Hg... 2+ It features highly selective identification and ultra-low detection limits, while also efficiently adsorbing Hg in water. 2+ Ultimately, this achieves a dual-function integrated application for the detection and removal of target pollutants, providing a solution for Hg in environmental water bodies. 2+ This provides new materials and technological ideas for comprehensive governance.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing an L-histidine-functionalized ZrTb-His-MOG fluorescent material, comprising the following steps: L-histidine and pyromellitic acid were dissolved in a mixed solvent of DMF and water, and then zirconium source and terbium source were added and stirred to obtain a mixed solution. The mixed solution was subjected to a hydrothermal reaction to obtain L-histidine-functionalized ZrTb-His-MOG fluorescent material. The molar ratio of L-histidine to pyromellitic acid is (0.5-1.5):1; The molar ratio of zirconium source to terbium source is (0.8-1.5):(1-2).

[0008] This preparation method is easy to synthesize, has mild reaction conditions, simple process requirements, high raw material utilization, easy gelation, and good material stability.

[0009] In some other embodiments, the volume ratio of DMF to water is (6-8):(2-4); the concentration of L-histidine is 0.02-0.03 mol / L.

[0010] Different DMF to water volume ratios affect the formation time and ease of ZrTb-His-MOG materials. Preferably, the DMF to water volume ratio is 7:3; and the L-histidine concentration is 0.025 mol / L.

[0011] In some other embodiments, the concentration of the zirconium source in the mixed solution is 0.03-0.06 mol / L; The hydrothermal reaction temperature is 90-110 ℃, and the time is 12-24 h; The zirconium source is one or more of zirconium chloride, zirconium sulfate, zirconium nitrate, and zirconium oxychloride; The terbium source is one or more of terbium nitrate, terbium chloride, terbium acetate, terbium carbonate, terbium fluoride, and terbium sulfate.

[0012] Preferably, the concentration of the zirconium source in the mixed solution is 0.05 mol / L; the hydrothermal reaction temperature is 100 ℃ and the time is 12 h; the zirconium source is zirconium chloride; and the terbium source is terbium nitrate.

[0013] In a second aspect, the present invention provides an L-histidine-functionalized ZrTb-His-MOG fluorescent material prepared by the method of preparing the L-histidine-functionalized ZrTb-His-MOG fluorescent material of the first aspect.

[0014] In some other embodiments, the L-histidine-functionalized ZrTb-His-MOG fluorescent material is composed of Zr 4+ 、Tb 3+ It is formed through coordination self-assembly with bifunctional ligands L-histidine and pyromellitic acid; L-histidine-functionalized ZrTb-His-MOG fluorescent materials have a three-dimensional porous network structure.

[0015] In some other embodiments, the molar ratio of L-histidine to pyromellitic acid is (0.5-1.5):1; The molar ratio of zirconium source to terbium source is (0.8-1.5):(1-2); Zr 4+ The molar ratio of L-histidine to L-histidine is (1-2):1.

[0016] Preferably, Zr 4+ :Tb 3+ The molar ratio of L-histidine to pyromellitic acid is 1:1; the molar ratio of Zr is 1:1. 4+ The molar ratio with L-histidine is 2:1.

[0017] A major challenge in lanthanide metal-organogel sensors is the difficulty in material synthesis. Lanthanide ions possess high coordination numbers and variable coordination geometries, often leading to the formation of interwoven coordination networks and dense structures in lanthanide organic gels. Simultaneously, the forbidden ff transitions of lanthanide ions result in weak fluorescence; only by selecting suitable ligands as "antennae" can energy be effectively transferred to the luminescent center. The sensor of this invention utilizes Zr... 4+ -L-histidine (L-His) ligand-metal charge transfer (LMCT) produces a 366 nm fluorescence signal, binding to trimesolic acid (BTC) → Tb 3+ The 546 nm fluorescence signal output by the antenna effect was used to construct a dual-signal ratio detection mechanism (I... 366 / I 546 This improves the reliability of the detection.

[0018] Thirdly, this invention provides an L-histidine-functionalized ZrTb-His-MOG fluorescent material in Hg 2+ Applications in detection and / or adsorption.

[0019] Hg 2+ The detection mechanism is as follows: Hg 2+ It specifically coordinates with the imidazole group of L-His, directly affecting the electron cloud distribution of L-His and causing a slight quenching of its 366 nm fluorescence signal (a reduction in fluorescence lifetime of 0.28 ns); on the other hand, it disrupts BTC→Tb³ + The antenna effect energy transfer path leads to Tb 3+ The characteristic fluorescence signal at 546 nm was significantly quenched (fluorescence lifetime shortened by 33.68 μs). This was achieved by calculating I... 366 / I 546 The ratio change achieves Hg 2+ High-sensitivity quantitative detection.

[0020] Hg 2+ Adsorption and capacity determination mechanism: The three-dimensional porous network structure of the material provides abundant adsorption sites, and the imidazole groups of L-His react with Hg. 2+ Forming stable coordinate bonds to achieve Hg 2+ The material exhibits highly efficient adsorption of Hg. By measuring the changes in the ultraviolet absorption spectrum of the sample before and after adsorption at a characteristic wavelength (300 nm), and combining this with adsorption kinetics and adsorption isotherm models, the material's adsorption capacity for Hg can be quantitatively calculated. 2+ Adsorption capacity.

[0021] Fourthly, the present invention provides a method for simultaneously detecting and adsorbing Hg. 2+ The method involves adding L-histidine-functionalized ZrTb-His-MOG fluorescent material to the sample, exciting it at a wavelength of 230 nm, and simultaneously acquiring fluorescence intensities at 366 nm and 546 nm. The ratio of the two signal intensities, I, is then calculated. 366 / I 546 To obtain Hg in the sample to be tested 2+ concentration; By measuring the UV absorption spectra of L-histidine-functionalized ZrTb-His-MOG fluorescent material at 300 nm before and after adsorption, the effect of L-histidine-functionalized ZrTb-His-MOG fluorescent material on Hg can be obtained. 2+ The amount of adsorption.

[0022] In some other embodiments, 1-3 mL of the test sample is added for every 3-6 mg of L-histidine-functionalized ZrTb-His-MOG fluorescent material.

[0023] In some other embodiments, the sample to be tested also contains Na. + K + Li + Ca 2+ Mg 2+ Fe 3+ Al 3+ Zn 2+ In 3+ Cd 2+ Ba 2+ Fe 2+ Co 2+ Ni 2+ Ag + and La 3+ One or more of them.

[0024] The beneficial effects of this invention are: (1) This invention uses L-histidine (L-His) and trimesic acid (BTC) as dual organic ligands to construct a novel type of bimetallic organogel (MOG) in synergy with zirconium (Zr) and terbium (Tb) bimetallic centers. Through multi-level synergistic effects of "ligand-ligand" and "ligand-metal", this material achieves the inhibition of mercury ions (Hg) 2+ It exhibits highly selective and sensitive fluorescence sensing response. Its detection performance is excellent, with a detection limit as low as 23 fM (femtomolar per liter) and good linearity over a wide range from 0.3 pM to 150 pM.

[0025] (2) The MOG material constructed in this invention uses I 366 (Ligand emission peak) and I 546 (Tb³) + A dual-channel ratiometric fluorescence detection mechanism (characteristic emission peak) is proposed. This mechanism utilizes two fluorescence signals to detect Hg. 2+ The differential response enabled the construction of a high signal-to-noise ratio internal reference detection system, effectively overcoming the shortcomings of single fluorescence signals being susceptible to interference from the environment and instrument fluctuations. Thanks to this robust ratio detection strategy, the material not only achieved an ultra-low detection limit of up to 23 fM, but also exhibited excellent anti-interference capabilities in complex matrices.

[0026] (3) The MOG material prepared in this invention not only performs efficient sensing but also functions as a high-performance adsorbent. Its adsorption capacity for Hg... 2+ The adsorption effect can be directly and quantitatively evaluated using a simple UV-Vis absorption spectroscopy method. This method requires no complex or expensive instruments, is simple and quick to operate, and provides great convenience and reliable technical support for the determination of adsorption capacity and performance evaluation of materials in practical applications. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 This invention relates to the synthesis and regeneration process of ZrTb-His-MOG, and the detection and adsorption of Hg in Example 1. 2+ A schematic diagram of the material's light-emitting mechanism; Figure 2 The images show fluorescence spectra of ZrTb-His-MOG ligand and metal doping ratio optimization experiments in Examples 1-2 of this invention; where a is the fluorescence emission spectrum under different ligand ratios and b is the fluorescence emission spectrum under different metal doping ratios. Figure 3 This is a photograph of the gel-forming material of ZrTb-His-MOG in Example 1 of this invention; Figure 4 The image shown is the XRD pattern of ZrTb-His-MOG in Embodiment 1 of the present invention. Figure 5 XPS plot of ZrTb-His-MOG in Embodiment 1 of the present invention; Figure 6 The infrared spectrum of ZrTb-His-MOG in Embodiment 1 of the present invention; Figure 7 The fluorescence emission spectrum of ZrTb-His-MOG in Example 1 of this invention is shown. Figure 8 This is an example of the fluorescence detection experiment of ZrTb-His-MOG in different metal ion solutions in Example 3 of the present invention; wherein, a is the fluorescence emission spectrum (inset showing color changes), b is the fluorescence quenching rate histogram, and c is the fluorescence emission spectrum of the material in a single metal ion solution for Hg. 2+ The quenched fluorescence emission spectrum (inset showing color changes); d represents the material's response to Hg in a solution doped with multiple metal ions. 2+ Quenched fluorescence emission spectrum (inset showing color changes); Figure 9 Different Hg values ​​in Embodiment 4 of the present invention 2+ Sensing performance analysis of ZrTb-His-MOG at different concentrations; where a is the fluorescence emission spectrum and b is the Ig emission spectrum. 366 / I 546 Ratio and Hg 2+ Linear fitting plot of concentration; Figure 10 The ZrTb-His-MOG in Embodiment 4 of this invention is used to treat Hg 2+Adsorption test analysis; where a is the pseudo-first-order kinetic model analysis of the material, b is the pseudo-second-order kinetic model analysis of the material, c is the adsorption isotherm analysis of the material, and d is the summary of the maximum adsorption capacity and equilibrium time of various adsorbents. Figure 11 The ZrTb-His-MOG material in Example 4 of this invention is used to treat Hg. 2+ The regeneration stability test; where 'a' represents the effect of five consecutive EDTA treatments on Hg. 2+ Fluorescence properties after desorption cycle, where b represents the desorbed Hg. 2+ The FT-IR spectrum of the material after desorption, c represents the Hg desorption. 2+ The XRD pattern of the material after processing. Detailed Implementation

[0029] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] Addressing the issue of existing materials having limited functionality and Hg 2+ To address the issues of separate detection and adsorption steps and insufficient detection stability, this invention proposes a ZrTb-His-MOG fluorescent material that utilizes an L-His / BTC dual ligand to react with Zr. 4+ / Tb 3+ Bimetallic co-assembly constructs an integrated material that combines fluorescence ratio detection and adsorption functions. The detection performance is optimized by utilizing the quenching difference of dual fluorescence signals, and the adsorption capacity is quantified by ultraviolet absorption spectroscopy.

[0031] The synthesis process, fluorescence detection, and adsorption mechanism of ZrTb-His-MOG fluorescent materials are as follows: Figure 1 As shown. This material is composed of zirconium ions (Zr). 4+ ), terbium ions (Tb 3+ It forms a three-dimensional porous network structure through coordination self-assembly with bifunctional ligands L-histidine (L-His) and pyromellitic acid (BTC), as shown in the following structural formula: ; The synthetic route for L-histidine-functionalized ZrTb-His-MOG fluorescent materials is as follows: .

[0032] Specifically, L-His and BTC were dissolved in a DMF / H2O mixed solvent and sonicated; then ZrCl4 and Tb(NO3)3·6H2O were added and magnetically stirred at room temperature until clear to obtain a mixed solution. The mixed solution was subjected to a solvothermal reaction to generate a white columnar gel; ZrTb-His-MOG powder was obtained by centrifugation, washing, freeze drying and grinding.

[0033] like Figure 1 As shown, the luminescence mechanism of L-histidine-functionalized ZrTb-His-MOG phosphor is as follows: the dual ligands L-histidine and BTC react with Tb 3+ Cooperative energy transfer between ions. Under ultraviolet irradiation, two parallel pathways are activated: in L-histidine, electrons transition from the ground state (S0) to the singlet excited state (S1), and then via intersystem crossing (ISC) to the triplet state (T1), and subsequently to Tb. 3+ Energy transfer occurs; simultaneously, BTC, acting as an antenna ligand, absorbs excitation energy to fill the excited state, thus achieving energy transfer to Tb. 3+ Resonant energy transfer at the center. This synergistic ligand system enhances energy transfer efficiency through functional complementarity: BTC primarily achieves energy capture through the antenna effect, while L-histidine achieves it through interaction with Tb. 3+ A multi-tooth coordination stable framework structure with Zr nodes. The resulting rigid microenvironment provides ideal conditions for energy transfer and emission processes. Ultimately, Tb in the excited state... 3+ occur 5 D4→ 7 F6 level transition (producing 546 nm green light emission). This is achieved via Zr... 4+ -L-His coordination produces a 366 nm LMCT fluorescence signal (I 366 ), combined with BTC→Tb 3+ The antenna effect outputs a fluorescence signal at 546 nm (I0). 546 ), forming a dual-signal ratio (I 366 / I 546 Dynamically compensates for environmental interference, significantly improving the protection against Hg. 2+ Selectivity and high sensitivity response.

[0034] Example 1 This embodiment provides an L-histidine-functionalized ZrTb-His-MOG fluorescent material and its preparation method, specifically including the following steps: L-histidine (L-His, 0.0776 g, 0.25 mmol) and 1,3,5-tristyric acid (BTC, 0.0525 g, 0.25 mmol) were dissolved in a DMF / H2O mixed solvent (DMF / H2O volume ratio 7 mL / 3 mL), and the mixture was sonicated for 30 min. Then, ZrCl4 (0.1165 g, 0.50 mmol) and Tb(NO3)3·6H2O (0.1130 g, 0.50 mmol) were added, and the mixture was magnetically stirred at room temperature for 25 min until clear, yielding a clear solution. The solution was transferred to a quartz flask and reacted at 100 °C for 12 h to obtain a white columnar gel. The gel was washed three times each with ethanol and deionized water by centrifugation, freeze-dried at -110 °C for 24 h, and then ground to obtain the target dry gel, labeled ZrTb-His-MOG.

[0035] Example 2 An L-histidine-functionalized ZrTb-His-MOG fluorescent material and its preparation method are disclosed. Unlike Example 1, the ratio of the ligand L-histidine to trimesic acid (molar ratio of (0.5-1.5):1) and the Zr / Tb ratio (Zr / Tb molar ratio of (0.8-1.5):(1-2)) are optimized, as follows: (1) Optimize the ratio of L-histidine to pyromellitic acid Unlike Example 1, while ensuring that the molar ratio of Zr / Tb is 1:1, the molar ratio of L-histidine and pyromellitic acid is set to 0.5:1 and 1.5:1, respectively, to prepare L-histidine-functionalized ZrTb-His-MOG, which are labeled as L-His / BTC=0.5:1 and L-His / BTC=1.5:1, respectively.

[0036] (2) Optimize the Zr / Tb ratio Unlike Example 1, while maintaining a 1:1 molar ratio of L-histidine to pyromellitic acid, the Zr / Tb molar ratio was set to 0.8:1 and 1.5:2, respectively, to prepare L-histidine-functionalized ZrTb-His-MOGs. These were labeled as Zr / Tb=0.8:1 and Zr / Tb=1.5:2, respectively.

[0037] The fluorescence properties of the L-histidine-functionalized ZrTb-His-MOG prepared above were investigated, and the results are as follows: Figure 2 As shown, a represents the fluorescence emission spectrum with different ligand ratios, and b represents the fluorescence emission spectrum with different metal doping ratios.

[0038] Depend on Figure 2As shown in Figure a, the fluorescence intensity at 366 nm initially increases and then decreases with increasing L-His ratio, reaching a peak at a molar ratio of 1:1. This indicates that an appropriate amount of L-histidine can enhance the energy transfer efficiency between the ligand and the metal ion, while an excessively high ratio triggers competition between ligands and weakens the fluorescence.

[0039] When Zr 4+ :Tb 3+ When the molar ratio increases from 0.8:1 to 1:1, the characteristic peak of L-His (366 nm) and Tb 3+ The fluorescence intensity of the characteristic peaks (490 nm, 546 nm, 590 nm, and 624 nm) was significantly enhanced. Figure 2 (b) indicates that an appropriate amount of Zr 4+ This can effectively enhance structural stability and promote energy transfer efficiency. Further increasing Zr... 4+ When the ratio reaches 1.5:2, the fluorescence intensity begins to decrease, which may be due to excessive Zr. 4+ This results in an overly compact structure, reducing rare-earth ion binding sites and inhibiting energy transfer. Analysis revealed that the molar ratio of L-histidine to pyromellitic acid was 1:1, and Zr... 4+ :Tb 3+ When the molar ratio is 1:1, ZrTb-His-MOG exhibits the best fluorescence performance (i.e., Example 1).

[0040] Figure 3 This is a physical image of the gel formed by ZrTb-His-MOG in Example 1; it appears as an opaque white columnar gel under natural light and emits bright green fluorescence under 254 nm ultraviolet light excitation.

[0041] Figure 4 The image shows the XRD pattern of ZrTb-His-MOG in Example 1. The smooth curve in the image indicates that the material has amorphous properties, and the weak diffraction peaks in the 20-30° range show that the material has a small amount of ordered crystalline phase structure.

[0042] Figure 5 This is the XPS plot of ZrTb-His-MOG in Example 1. The characteristic peaks at 520-540 eV, 390-410 eV, and 280-290 eV correspond to O 1s, N 1s, and C 1s, respectively; the characteristic peaks at 175-185 eV and 1230-1300 eV correspond to Zr 3d and Tb 3d, respectively; and a Tb-O characteristic peak appears at 140 eV, confirming that Zr... 4+ 、Tb 3+ Successfully incorporated and formed a coordination network.

[0043] Figure 6The infrared spectrum of ZrTb-His-MOG in Example 1; 2700-3500 cm⁻¹ -1 The ν(OH) band, 1640cm -1 The ν(C=O) band confirms that the carboxylic acid oxygen participates in coordination, 1616 cm -1 The ν(C=N) stretching vibration peak confirms successful L-His incorporation, 650 cm⁻¹ -1 The ν(Zr-O) tensile vibration peak indicates that Zr 4+ It coordinates with carboxyl groups to form a network structure.

[0044] Figure 7 This is the fluorescence emission spectrum of ZrTb-His-MOG in Example 1; from Figure 7 It can be seen that the fluorescence peak at 366 nm is L-His, and the peaks at 490 nm, 546 nm, 590 nm, and 624 nm are Tb. 3+ of 5 D4→ 7 F6 5 D4→ 7 F5 5 D4→ 7 F4 and 5 D4→ 7 The F3 characteristic transition peak causes the ZrTb-His-MOG material to emit green light under ultraviolet excitation at 254 nm.

[0045] Example 3 This embodiment studies the effect of ZrTb-His-MOG on Hg. 2+ The specific identification and anti-interference performance are determined by the following steps: (1) Specific recognition test: 5 mg ZrTb-His-MOG powder was mixed with 1 mL of different metal ion solutions (Hg 2+ Na + K + Li + Ca 2+ Mg 2+ Fe 3+ Al 3+ Zn 2+ In 3+ Cd 2+ Ba 2+ Fe 2+ Co 2+ Ni 2+ Ag + La 3+ (The metal ion concentration was 1 μM) and the mixture was ultrasonically mixed. The fluorescence spectrum and fluorescence quenching rate were measured under 230 nm excitation.

[0046] (2) Single interfering ion coexistence test: 5 mg ZrTb-His-MOG powder was mixed with 1 mL of Hg-containing... 2+ (1 μM) and a single interfering ion (Na) + K + Li + Ca 2+ Mg 2+ Fe 3+ Al 3+ Zn 2+ In 3+ Cd 2+ Ba 2+ Fe 2+ Co 2+ Ni 2+ Ag + La 3+ A mixed solution (each with a concentration of 50 μM) was ultrasonically mixed, and the fluorescence spectrum was measured under 230 nm excitation. The results are as follows: Figure 8 As shown in c.

[0047] (3) Multiple interfering ion coexistence test: 5 mg ZrTb-His-MOG powder was mixed with 1 mL of Hg 2+ (1 μM) and various interfering ions (Na) + K + Li + Ca 2+ Mg 2+ Fe 3+ Al 3+ Zn 2+ In 3+ Cd 2+ Ba 2+ Fe 2+ Co 2+ Ni 2+ Ag + La 3+ A mixed solution (each with a concentration of 50 μM) was ultrasonically mixed, and the fluorescence spectrum was measured under 230 nm excitation. The results are as follows: Figure 8 As shown in d.

[0048] Depend on Figure 8 From 'a' in the text, we can see that only Hg 2+ When present, the fluorescence intensity at 546 nm is significantly quenched, the fluorescence intensity at 366 nm decreases slightly, and the fluorescence color turns blue (inset); other metal ions have little effect on the fluorescence signal. Figure 8 In b, Hg 2+ The fluorescence quenching rate of this system is significantly higher than that of other metal ion systems, confirming the material's resistance to Hg. 2+Its specific recognition capability. Figure 8 In the c and d components, whether a single or multiple interfering ions coexist, the material's effect on Hg... 2+ The fluorescence still retains the quenching effect, and the fluorescence color remains blue (inset), indicating that the material has extremely strong anti-interference ability.

[0049] Example 4 This embodiment tests the effect of ZrTb-His-MOG on Hg. 2+ The sensing performance and adsorption capacity were determined by the following steps: (1) Sensing performance test: 5 mg ZrTb-His-MOG powder was mixed with 1 mL of Hg at different concentrations. 2+ The solutions (0.001-150 pM) were ultrasonically mixed, and the fluorescence spectrum and Ig were measured under 230 nm excitation. 366 / I 546 The ratio, the result is as follows Figure 9 As shown.

[0050] (2) Adsorption capacity test: 5 mg ZrTb-His-MOG powder was mixed with 10 mL Hg 2+ The solutions were mixed, and the ultraviolet absorption spectra were measured at different adsorption times. Adsorption kinetics were analyzed, and adsorption isotherm analysis was performed to calculate the adsorption capacity and maximum adsorption amount. The results are as follows: Figure 10 As shown Depend on Figure 9 As can be seen from 'a' in Hg, 2+ With increasing concentration, the fluorescence at 366 nm was slightly quenched, and the fluorescence at 546 nm was significantly quenched. Furthermore, a noticeable color change was observed under UV light, with increasing Hg... 2+ The concentration increased and the color changed from green to blue. Figure 9 (The inline image of 'a'). Figure 9 In b, I 366 / I 546 Ratio and Hg 2+ The concentration showed a good linear relationship in the range of 0.3-150 pM, and the linear equation was I. 366 / I 546 =0.025C Hg2++6.36,R 2 =0.99, with a minimum detection limit of 23 fM.

[0051] Depend on Figure 10 Adsorption kinetics analysis of a and b in the data shows that the material has a high affinity for Hg. 2+ The adsorption of ZrTb-His-MOG is more consistent with the second-order kinetic model, indicating that chemisorption plays a dominant role in the adsorption process. 2+ It exhibits excellent adsorption performance, with an adsorption capacity of 813.08 mg / g after 140 minutes, after which adsorption equilibrium is reached. Figure 10 In the c-value, adsorption isotherm analysis showed that the correlation coefficient of the Langmuir model was higher than that of the Freundlich model, and the theoretical maximum value obtained by the Langmuir model was 833.16 mg / g, which is closer to the actual experimental value. Therefore, ZrTb-His-MOG has a better effect on Hg. 2+ The adsorption of is a monolayer adsorption; Figure 10 In d, ZrTb-His-MOG and other adsorbent materials for Hg 2+ A comparison of adsorption capacity and time shows that the high specific surface area and fast mass transfer channels provided by the three-dimensional cross-linked porous structure of ZrTb-His-MOG material, as well as the abundant highly active exclusive coordination sites constructed by the Zr / Tb bimetallic center and functional groups such as histidine imidazole group and amino group, enable the material to exhibit significant advantages in adsorption capacity and adsorption rate.

[0052] Depend on Figure 11 The cyclic fluorescence performance test results of material 'a' in the figure show that after Hg adsorption... 2+ The fluorescence response intensity of the ZrTb-His-MOG material remained stable after EDTA desorption treatment (5 cycles), indicating that EDTA can strongly coordinate with Hg adsorbed on the material surface. 2+ Effective combination to achieve Hg 2+ The material exhibits highly efficient desorption, and the desorption process does not damage the fluorescent sensing active sites of the material. The material also demonstrates high sensitivity to Hg. 2+ The recognition and response capabilities did not change significantly during the cycle. Figure 11 The FT-IR spectral characterization results of b in the figure show that the position and intensity of the characteristic functional group absorption peaks of the material did not change significantly before and after five cycles, indicating that the EDTA desorption process did not induce the breakage or structural reconstruction of the coordination active sites (such as imidazole groups, carboxyl groups, etc.) on the material surface. Figure 11 The XRD pattern of c in the figure shows that the crystal structure of the material remains intact during the cyclic adsorption-desorption process, and the characteristic diffraction peaks do not shift or broaden, indicating that the framework structure of the material has good rigidity and stability. The above cyclic experimental results show that the ZrTb-His-MOG material exhibits good rigidity and stability in fluorescence-quenched Hg. 2+ It exhibits both excellent regeneration performance and structural stability during testing.

[0053] The excellent reliability was verified by the recovery rate of spiked samples. Deionized water, drinking water, tap water, and lake water were used as actual samples for detection. Under optimal detection conditions, Hg in the four water samples was determined. 2+ Prior to analysis, all water samples were filtered three times, and Hg was determined using a fluorescence spectrophotometer. 2+ The fluorescence spectra after addition are shown in Table 1.

[0054] Table 1 Hg in actual samples 2+ Test results

[0055] The results are shown in Table 1. The recoveries ranged from 93.0% to 103.7%. Hg was measured using the ZrTb-His-MOG fluorescence sensing method. 2+ Concentration value and the actual spiked Hg in the sample 2+ The concentration values ​​showed a high degree of agreement, proving that ZrTb-His-MOG can be used for Hg in actual water bodies. 2+ The detection.

[0056] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an L-histidine-functionalized ZrTb-His-MOG fluorescent material, characterized in that, Includes the following steps: L-histidine and pyromellitic acid were dissolved in a mixed solvent of DMF and water, and then zirconium source and terbium source were added and stirred to obtain a mixed solution. The mixed solution was subjected to a hydrothermal reaction to obtain L-histidine-functionalized ZrTb-His-MOG fluorescent material. The molar ratio of L-histidine to pyromellitic acid is (0.5-1.5):1; The molar ratio of the zirconium source to the terbium source is (0.8-1.5):(1-2).

2. The method for preparing L-histidine-functionalized ZrTb-His-MOG fluorescent material according to claim 1, characterized in that, The volume ratio of DMF to water is (6-8):(2-4); the concentration of L-histidine is 0.02-0.03 mol / L.

3. The method for preparing L-histidine-functionalized ZrTb-His-MOG fluorescent material according to claim 1, characterized in that, The concentration of the zirconium source in the mixed solution is 0.03-0.06 mol / L; The hydrothermal reaction is carried out at a temperature of 90-110 ℃ for a duration of 12-24 h. The zirconium source is one or more of zirconium chloride, zirconium sulfate, zirconium nitrate, and zirconium oxychloride; The terbium source is one or more of terbium nitrate, terbium chloride, terbium acetate, terbium carbonate, terbium fluoride, and terbium sulfate.

4. The L-histidine-functionalized ZrTb-His-MOG fluorescent material prepared by the method described in any one of claims 1-3.

5. The L-histidine-functionalized ZrTb-His-MOG fluorescent material according to claim 4, characterized in that, The L-histidine-functionalized ZrTb-His-MOG fluorescent material is made from Zr 4+ 、Tb 3+ It is formed through coordination self-assembly with bifunctional ligands L-histidine and pyromellitic acid; The L-histidine-functionalized ZrTb-His-MOG fluorescent material has a three-dimensional porous network structure.

6. The L-histidine-functionalized ZrTb-His-MOG fluorescent material according to claim 4, characterized in that, The molar ratio of L-histidine to pyromellitic acid is (0.5-1.5):1; The molar ratio of the zirconium source to the terbium source is (0.8-1.5):(1-2); The Zr 4+ The molar ratio of L-histidine to L-histidine is (1-2):

1.

7. A ZrTb-His-MOG fluorescent material functionalized with L-histidine according to any one of claims 4-6 in Hg 2+ Applications in detection and / or adsorption.

8. A method for simultaneous detection and adsorption removal of Hg 2+ The method is characterized by, The L-histidine-functionalized ZrTb-His-MOG fluorescent material as described in claim 4 or 5 was added to the sample to be tested. It was excited at a wavelength of 230 nm, and the fluorescence intensity at 366 nm and 546 nm was simultaneously acquired. The ratio of the two signal intensities, I, was calculated. 366 / I 546 To obtain Hg in the sample to be tested 2+ concentration; By measuring the UV absorption spectra of L-histidine-functionalized ZrTb-His-MOG fluorescent material at 300 nm before and after adsorption, the effect of L-histidine-functionalized ZrTb-His-MOG fluorescent material on Hg can be obtained. 2+ The amount of adsorption.

9. The method for simultaneous detection and adsorption removal of Hg according to claim 8 2+ The method is characterized by, Add 1-3 mL of the test sample to each 3-6 mg L-histidine-functionalized ZrTb-His-MOG fluorescent material.

10. The method for simultaneous detection and adsorption removal of Hg according to claim 8 2+ The method is characterized by, The sample to be tested also contains Na. + K + Li + Ca 2+ Mg 2+ Fe 3+ Al 3+ Zn 2+ In 3+ Cd 2+ Ba 2+ Fe 2+ Co 2+ Ni 2+ Ag + and La 3+ One or more of them.

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