A self-calibration dual-channel MOF ratio fluorescent sensing material and its method for rapid visual detection of phosphate

Abstract

This invention relates to the field of chemical analysis and detection technology, specifically to a self-calibrated dual-channel MOF ratio fluorescence sensing material and its application in a rapid visual detection method for phosphate. The problem addressed by this invention is that existing phosphate detection technologies suffer from slow response speed, poor material stability, and low detection accuracy and difficulty in rapid on-site quantification due to the lack of self-calibration functionality. To solve these problems, this invention constructs an internal reference luminescent component + Eu luminescent component within the same MOF carrier. 3+ A self-calibrating dual-emission system with a "-TTA response channel" and utilizing Pi-Eu 3+ Competition-triggered local antenna replacement enables rapid, stable, wide-environment-applicable, and highly interference-resistant visualization / quantitative detection of phosphates via mobile phones. It overcomes the problems commonly found in existing technologies, such as complex high-temperature solvothermal processes, inconvenience of deep ultraviolet excitation in the field, poor stability due to reliance on frame destruction, slow response due to multiple steps, and insufficient field consistency.

Description

Technical Field

[0001] This invention relates to the field of chemical analysis and detection technology, and in particular to a self-calibrated dual-channel MOF ratio fluorescence sensing material and its application in a rapid visual detection method for phosphate. Background Technology

[0002] Phosphate (Pi), a key nutrient element in aquatic ecosystems and an important participant in energy metabolism, is crucial for accurate monitoring to prevent eutrophication and aid in related clinical diagnosis. Traditional detection methods, such as ion chromatography and molybdenum blue colorimetry, while technically mature, often rely on expensive precision instruments, complex chemical reagent preparation, and cumbersome sample pretreatment processes, making them unsuitable for rapid on-site screening in cases of sudden environmental pollution. In recent years, ratiometric fluorescent probes based on metal-organic frameworks (MOFs) have become a research hotspot in rapid on-site detection due to their self-calibration capabilities, high sensitivity, and visual visibility. These probes can effectively eliminate interference from excitation light fluctuations and complex backgrounds by varying the intensity ratio of two independent emission channels.

[0003] However, existing phosphate fluorescence sensing technologies still face significant challenges in their practical application. First, most MOF-based sensors rely on relatively crude mechanisms, often depending on phosphate-induced framework collapse or competitive decomposition to release signal molecules. This results in slow response times and poor material structural stability, making them prone to irreversible drift. Second, some probes require deep ultraviolet excitation and are extremely sensitive to environmental pH, limiting their application in extreme natural water environments or portable mobile detection scenarios. Therefore, developing a self-calibrating dual-channel fluorescence sensing system capable of rapid response under near-ultraviolet excitation, possessing robust physicochemical stability, and adaptable to quantitative analysis on smartphones has become a pressing technical challenge in the fields of chemical analysis and environmental engineering. Summary of the Invention

[0004] The problem solved by this invention is that existing phosphate detection technologies suffer from slow response speed, poor material stability, and low detection accuracy due to lack of self-calibration function, making it difficult to quickly quantify on-site.

[0005] To address the aforementioned problems, this invention provides a self-calibrating dual-channel MOF ratio fluorescence sensing material, comprising a main framework, an internal reference luminescent component, and a responsive luminescent component; the main framework is Eu. 3+ The doped ZIF-8 metal-organic framework is denoted as Eu-ZIF-8; the internal reference luminescent component is 9-aminoacridine confined in the channels of Eu-ZIF-8; the responsive luminescent component is 2-thiamethoxyacetylacetone and Eu 3+The sensitized luminescent center formed by coordination is denoted as Eu. 3+ -TTA.

[0006] Preferably, the material simultaneously generates blue and red dual-channel fluorescence emission under single-wavelength excitation.

[0007] Preferably, the single wavelength is 365 nm near-ultraviolet light.

[0008] Preferably, the range of the single wavelength is 350-380 nm near-ultraviolet light.

[0009] This invention also provides a method for preparing a self-calibrating dual-channel MOF ratio fluorescence sensing material, comprising the following steps:

[0010] The first step involves mixing 9-aminoacridine solution, zinc salt solution, and Eu... 3+ After mixing the salt solutions, they were reacted with 2-methylimidazole solution at room temperature to give 9-AA@Eu-ZIF-8;

[0011] In the second step, 9-AA@Eu-ZIF-8 was dispersed in ethanol, and 2-thiamethoxyacetylacetone was added to carry out a coordination reaction to obtain 9-AA@Eu-ZIF-8@TTA.

[0012] Preferably, the zinc salt solution is a zinc nitrate solution, and the Eu... 3+ The salt solution is a europium nitrate solution.

[0013] Preferably, the concentration of the 9-aminoacridine solution is 0.5-6.0 mg / mL.

[0014] Preferably, the concentration of the 2-methylimidazole solution is 0.15-0.417 g / mL.

[0015] Preferably, the concentration of the zinc nitrate solution is 50-250 mg / mL.

[0016] Preferably, the concentration of the europium nitrate solution is 26.67-120 mg / mL.

[0017] Preferably, the concentration of the 2-methylimidazole solution is 0.18-0.367 g / mL.

[0018] Preferably, the concentration of the 9-aminoacridine solution is 0.75-5.0 mg / mL.

[0019] Preferably, the concentration of the zinc nitrate solution is 60-220 mg / mL.

[0020] Preferably, the concentration of the europium nitrate solution is 30-110 mg / mL.

[0021] Preferably, the mass ratio of 2-thiayltrifluoroacetylacetone to 9-AA@Eu-ZIF-8 powder is (0.1-0.5):1.

[0022] This invention also provides a method for rapid visual detection of phosphate using a self-calibrated dual-channel MOF ratio fluorescence sensing material, characterized by comprising the following steps:

[0023] Mix the sample to be tested with the suspension of the fluorescent sensing material and let it stand until the response equilibrium is reached;

[0024] Qualitative or quantitative detection of phosphate can be achieved by detecting the ratio of dual-channel fluorescence signals or the grayscale ratio of image channels in a mixed system under ultraviolet light excitation.

[0025] Preferably, the quantitative detection employs fluorescence spectrophotometry: under ultraviolet light irradiation, the fluorescence intensity of the mixture at 460 nm and 617 nm is measured, and then analyzed using F... 617 / F 460 The ratio enables quantitative detection of phosphate; the method has a linear detection range of 0-80 μM, a detection limit of 0.48 μM, a response time of 0.3-1.0 min, and maintains an effective response within the pH range of 3-11.

[0026] Preferably, the method further includes a visual detection and portable quantification step:

[0027] Under 365 nm ultraviolet light irradiation, the fluorescence color change of the mixed system can be directly observed to achieve visual qualitative or semi-quantitative detection of phosphate;

[0028] Fluorescence images of the system in a darkroom environment were acquired using a smartphone. The red channel value R and the blue channel value B in the images were extracted. Phosphate was quantitatively detected based on the R / B ratio. The linear range of the quantitative detection was 0-80 μM, the response time was 0.3-1.0 min, and it maintained an effective response within the pH range of 3-11.

[0029] Preferably, the rapid visual detection method for phosphate can be used to detect phosphate in other water samples such as tap water, lake water, river water, reservoir water, groundwater, aquaculture water, domestic sewage, and industrial wastewater.

[0030] The beneficial effects of this invention are:

[0031] The preparation process is simple and mild, and easy to scale up: The sensor material is prepared by a two-step method at room temperature. The entire process does not require high temperature and high pressure solvothermal conditions. The steps are simple, the energy consumption is low, and it is easy to control batch consistency, which reduces production costs and facilitates subsequent engineering scale-up.

[0032] Excellent self-calibration performance and high detection accuracy: It integrates a 9-AA (9-aminoacridine) internal reference luminescence channel and an Eu luminescence channel within the same MOF platform. 3+ - The TTA-responsive luminescence channel eliminates signal crosstalk and effectively eliminates interference from external factors such as probe dosage, light source fluctuations, and sample turbidity through ratiometric fluorescence signal output, thereby improving the accuracy and repeatability of quantitative detection.

[0033] Rapid detection response, suitable for rapid on-site screening: phosphate and Eu 3+ The competitive coordination reaction is rapid. The 9-AA@Eu-ZIF-8 probe can reach a stable response within 0.5 minutes after being added to the sample, which is far superior to existing detection technologies that require long incubation. It is suitable for rapid screening and emergency detection of environmental water samples.

[0034] Excellent detection performance and strong environmental adaptability: The linear detection range for phosphate is 0-80 μM, with a detection limit as low as 0.48 μM, meeting the detection needs of common environmental water samples; it maintains effective detection response over a wide pH range of 3-11, demonstrating good applicability to aqueous phases; relying on phosphate and Eu... 3+ Its strong coordination enables highly selective recognition, resists interference from common anions and cations as well as organic anions, and reduces the risk of misjudgment.

[0035] The detection method is flexible and portable, and highly adaptable to the field: the sensing material can achieve dual-channel fluorescence readout under single-wavelength excitation by a 365 nm universal ultraviolet light source, avoiding the limitations of deep ultraviolet excitation; it exhibits a visible fluorescence color change with the change of phosphate concentration, and can also be combined with smartphone RGB image analysis to achieve semi-quantitative or quantitative detection without large instruments, making it suitable for field detection scenarios such as field and grassroots.

[0036] Excellent material and detection signal stability: Detection based on Eu 3+ Changes in the local coordination environment do not depend on the collapse or decomposition of the MOF main framework to release luminescent components, and the signal output is stable without drift; the ratio fluorescence signal of the sensing material remains basically stable within 7 days of storage, demonstrating good storage and use stability.

[0037] The design concept has the potential for platform expansion: The modular design concept of "pore-confined internal reference + metal site response + competitive coordination triggering ratio change" of this invention has universality. By changing the lanthanide ions, antenna ligands or target metal sites, it is expected to expand and build a ratiometric fluorescence detection platform for other analytes, and the scope of application can be further extended. Attached Figure Description

[0038] Figure 1 This is a schematic diagram illustrating the preparation process and phosphate detection mechanism of a self-calibrating dual-channel MOF ratio fluorescence sensing material according to the present invention.

[0039] Figure 2 The images show the powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), and ultraviolet-visible absorption (UV-vis) spectra of the 9-AA@Eu-ZIF-8@TTA material during the stepwise assembly process of this invention.

[0040] Figure 3 The X-ray photoelectron spectroscopy (XPS) spectrum of the 9-AA@Eu-ZIF-8@TTA material of this invention, as well as the high-resolution spectra of Eu 3d, F1s, N 1s, Zn 2p and S 2p, are shown.

[0041] Figure 4 The images show transmission electron microscopy (TEM) images and elemental distribution energy distribution mapping (EDS) images of the 9-AA@Eu-ZIF-8@TTA material of this invention.

[0042] Figure 5 This is a comparison of the three-dimensional fluorescence spectrum (3D-EEM) of the 9-AA@Eu-ZIF-8@TTA material of this invention;

[0043] Figure 6 The following are fluorescence spectrum changes of the 9-AA@Eu-ZIF-8@TTA material of the present invention at different phosphate concentrations: F 617 / F 460 Linear relationship between ratio and phosphate concentration, and color coordinate variation graph;

[0044] Figure 7 The graph shows the linear relationship between the color change of the 9-AA@Eu-ZIF-8@TTA material of this invention under ultraviolet irradiation and the R / B ratio of a mobile phone, as well as the selectivity / anti-interference results.

[0045] Figure 8 Comparison of powder X-ray diffraction patterns, Fourier transform infrared spectra, and X-ray photoelectron spectroscopy of the 9-AA@Eu-ZIF-8@TTA material before and after the addition of phosphate.

[0046] Figure 9 The images show transmission electron microscopy (TEM) images and elemental distribution energy distribution mapping diagrams of the 9-AA@Eu-ZIF-8@TTA material of this invention after the addition of phosphate.

[0047] Figure 10 The graphs show the time-resolved fluorescence decay curves of the 9-AA@Eu-ZIF-8@TTA material of this invention at 460 nm and 617 nm under different phosphate concentrations.

[0048] Figure 11 This is a dynamic light scattering particle size distribution (DLS) diagram of the 9-AA@Eu-ZIF-8@TTA material of the present invention;

[0049] Figure 12 This is a comparison of the excitation and emission spectra of the 9-AA@Eu-ZIF-8@TTA material of the present invention;

[0050] Figure 13 These are comparative photographs of samples of the 9-AA@Eu-ZIF-8@TTA material of the present invention at different preparation stages, under visible light and 365 nm ultraviolet light irradiation.

[0051] Figure 14 The 9-AA@Eu-ZIF-8@TTA material of this invention, under a specific phosphate concentration, F 617 / F 460 A graph showing the ratio changing over time;

[0052] Figure 15 The graph shows the fluorescence response of the 9-AA@Eu-ZIF-8@TTA material of this invention under different pH conditions.

[0053] Figure 16 The image shows the luminescence stability test results of the 9-AA@Eu-ZIF-8@TTA material of this invention over several consecutive days. Detailed Implementation

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] This invention provides a self-calibrated dual-channel MOF ratio fluorescence sensing material, the material comprising a main framework, an internal reference luminescent component, and a responsive luminescent component;

[0056] The main frame is Eu 3+ The doped ZIF-8 metal-organic framework, denoted as Eu-ZIF-8, is used to provide a stable porous framework and realize Eu 3+ Site immobilization.

[0057] The internal reference luminescent component is 9-aminoacridine confined in the Eu-ZIF-8 channels;

[0058] The responsive luminescent components are 2-thiamethoxam trifluoroacetylacetone (TTA) and Eu. 3+ Sensitized luminescent centers formed through coordination.

[0059] In some embodiments, the material simultaneously produces blue and red dual-channel fluorescence emission under single-wavelength excitation.

[0060] In some embodiments, the single wavelength is 365nm near-ultraviolet light.

[0061] In some embodiments, the single wavelength range is 350-380 nm near-ultraviolet light.

[0062] In this invention, the self-calibrated dual-channel MOF ratio fluorescence sensing material can simultaneously generate blue and red dual-channel fluorescence emission under a single excitation wavelength, which is used to construct a ratiometric detection signal, facilitating visualization and portable detection.

[0063] In this invention, the preferred emission peak of the internal reference luminescent component is located at approximately 460 nm. As a blue reference signal that is essentially insensitive to phosphate, it remains relatively stable during phosphate detection and serves as a reference signal to correct errors caused by changes in external conditions.

[0064] In this invention, the preferred emission peak of the responsive luminescent component is located at approximately 617 nm. This serves as a red signal channel selectively responsive to phosphate, exhibiting responsiveness to the presence of phosphate. The luminescence intensity changes under the influence of phosphate, reflecting the concentration of the phosphate to be measured. Specifically, TTA acts as an antenna ligand at the sensitized luminescent center, absorbing excitation energy and transferring it to Eu. 3+ It can enhance Eu 3+ Red emission, when phosphate is present, phosphate reacts with Eu. 3+ Strong coordination occurs between them, and they coordinate with the original Eu site. 3+ Competition arises between TTAs on the surface, leading to Eu 3+ - Changes in the local coordination environment of TTA cause selective attenuation of the red light channel, while the blue light channel remains basically stable, thus achieving a self-calibration ratio.

[0065] It should be noted that antenna ligands refer to those capable of absorbing excitation energy and transferring it to Eu. 3+ The luminescent center, thereby enhancing Eu 3+ The characteristic emission ligand, in this invention, TTA is Eu. 3+ Antenna ligands.

[0066] In this invention, the term "confined domain" refers to the state in which the functional molecule 9-AA is introduced into and confined within the pores, cavities, or internal microenvironment of the Eu-ZIF-8 framework. It should be noted that the confinement does not require 9-AA to form covalent bonds with the framework, but rather includes situations where it stably exists within the framework or pore environment through pore encapsulation, physical embedding, host-guest interactions, or other non-covalent interactions.

[0067] In this invention, the self-calibrating dual-channel MOF ratio fluorescence sensing material simultaneously includes an internal reference emission channel that is essentially insensitive to phosphate and an emission channel that selectively responds to phosphate. During the detection process, the ratio of the fluorescence intensity of the two channels is used as the output signal, thereby reducing the influence of factors such as the dosage of the self-calibrating dual-channel MOF ratio fluorescence sensing material, excitation light intensity fluctuations, sample turbidity, background interference, and instrument drift on the detection results.

[0068] This invention also provides a method for preparing a self-calibrating dual-channel MOF ratio fluorescence sensing material, comprising the following steps:

[0069] The first step involves mixing 9-aminoacridine solution, zinc salt solution, and Eu... 3+ After mixing the salt solutions, they were reacted with 2-methylimidazole solution at room temperature to give 9-AA@Eu-ZIF-8;

[0070] In the second step, 9-AA@Eu-ZIF-8 was dispersed in ethanol, and 2-thiamethoxyacetylacetone was added to carry out a coordination reaction to obtain 9-AA@Eu-ZIF-8@TTA.

[0071] In some embodiments, the zinc salt solution is a zinc nitrate solution, and the Eu... 3+ The salt solution is a europium nitrate solution.

[0072] In some embodiments, the concentration of the 9-aminoacridine solution is 0.5-6.0 mg / mL, for example 0.5 mg / mL, 1.2 mg / mL, 3.0 mg / mL, 5.0 mg / mL or 6.0 mg / mL. This concentration range can be adjusted according to the expected fluorescence intensity and encapsulation effect. Too low a concentration will result in insufficient internal reference signal, while too high a concentration may cause molecular aggregation, unstable loading, or affect the formation of the material framework, thereby reducing product stability and detection performance.

[0073] In some embodiments, the concentration of the zinc nitrate solution is 50-250 mg / mL, such as 50 mg / mL, 80 mg / mL, 150 mg / mL, 200 mg / mL or 250 mg / mL. As the metal source of the MOF framework, the concentration of the zinc salt needs to ensure that the framework can nucleate and grow normally. If the concentration is too low, the crystal growth will be incomplete and the crystallinity of the product will be poor. If the concentration is too high, it will easily produce amorphous precipitation and it will be difficult to obtain a regular porous target framework structure.

[0074] In some embodiments, the concentration of the europium nitrate solution is 26.67-120 mg / mL, for example 26.67 mg / mL, 40 mg / mL, 70 mg / mL, 100 mg / mL, or 120 mg / mL. 3+As the core component of the response site, when its concentration is too low, the doping effect is not obvious and it is difficult to achieve the expected fluorescence characteristics; when its concentration is too high, it may destroy the orderly formation of the ZIF-8 framework, leading to the generation of secondary phases or a decrease in material stability. This concentration range can ensure that the doping amount is adapted to the stability requirements of the framework structure.

[0075] In some embodiments, the concentration of the 2-methylimidazole solution is 0.15-0.417 g / mL, for example, 0.15 g / mL, 0.2 g / mL, 0.3 g / mL, 0.38 g / mL, or 0.417 g / mL. As an organic ligand for constructing the ZIF-8 framework, the amount of 2-methylimidazole significantly affects the formation of the framework structure and the crystallinity of the product. When the amount of 2-methylimidazole is too low, it can lead to insufficient framework construction, decreased product crystallinity, and reduced encapsulation efficiency; when the amount is too high, it can lead to an excessively rapid nucleation rate, uneven particle size distribution, and even affect the effective introduction of Eu and 9-AA. Therefore, the amount of 2-methylimidazole is preferably controlled within the above-mentioned range.

[0076] Further preferably, the concentrations of 9-aminoacridine solution are controlled at 0.75-5.0 mg / mL, zinc nitrate solution at 60-220 mg / mL, europium nitrate solution at 30-110 mg / mL, and 2-methylimidazole solution at 0.18-0.367 g / mL. Products prepared within this parameter range exhibit the best crystallinity and the most stable ratio of dual-channel fluorescence signal intensity.

[0077] In some embodiments, the mass ratio of 2-thiamethoxytrifluoroacetylacetone to 9-AA@Eu-ZIF-8 powder is (0.1-0.5):1, for example 0.1:1, 0.2:1, 0.3:1, 0.4:1 or 0.5:1, with TTA as Eu 3+ The proportion of sensitized antenna ligands used directly affects Eu. 3+ The initial red emission intensity, when TTA dosage is insufficient, Eu 3+ The coordination sites cannot be fully occupied, resulting in low red light emission intensity after sensitization, which fails to obtain sufficient initial signal contrast and is detrimental to the differentiation of subsequent response signals. Furthermore, when the amount of TTA is too large, the excess TTA cannot fully bind to Eu. 3+ Excess free TTA can remain in the material pores or on the surface, affecting the surface condition and stability, and consequently the detection performance. Therefore, controlling the TTA within this mass ratio range ensures sufficient TTA coordination without wasting raw materials, resulting in a stable initial red light emission signal. The amount of 9-AA@Eu-ZIF-8 added affects the concentration of the dispersion system and the TTA-Eu ratio. 3+The coordination efficiency of the sites is affected by the following: when the amount of 9-AA@Eu-ZIF-8 is too low, the number of active sites in the system is insufficient, which is not conducive to forming a stable and effective fluorescence response; when the amount is too high, it leads to uneven dispersion or particle aggregation, thereby affecting the coordination modification effect and the final performance of the 9-AA@Eu-ZIF-8 probe.

[0078] The above preparation process is carried out at room temperature. In the first step of the reaction, 9-aminoacridine is dissolved in methanol to obtain a 9-aminoacridine solution, and 2-methylimidazole is dissolved in water to obtain a 2-methylimidazole aqueous solution. Zn(NO3)2·6H2O and Eu(NO3)3·6H2O are dissolved in 1.0-3.0 mL of water respectively to obtain the corresponding metal salt solutions. The 9-aminoacridine solution, zinc salt solution, and Eu... 3+ After mixing the salt solutions, stir for 1-5 min, then add the 2-methylimidazole aqueous solution dropwise to the mixture and continue stirring at room temperature for 20-60 min. After the reaction is complete, collect the resulting suspension by centrifugation, wash with water and ethanol sequentially, and dry to obtain 9-AA@Eu-ZIF-8.

[0079] In the second step of the reaction, the 9-AA@Eu-ZIF-8 obtained in the first step was dispersed in ethanol, TTA was added, and the mixture was stirred at room temperature for 10-40 min to allow the TTA to react with the Eu. 3+ Coordination occurs at the sites; after the reaction, the resulting system is centrifuged, washed, and dried to obtain 9-AA@Eu-ZIF-8@TTA. The stirring time affects the reaction between TTA and Eu. 3+ The degree of coordination between sites is crucial. If the stirring time is too short, the coordination is insufficient, which is detrimental to the formation of the target dual-channel probe; if the stirring time is too long, it can cause particle aggregation and waste time. Therefore, the stirring time is preferably controlled within the above range.

[0080] This invention also provides a method for rapid visual detection of phosphate using a self-calibrated dual-channel MOF ratio fluorescence sensing material, characterized by comprising the following steps:

[0081] The sample to be tested is mixed with the suspension of the fluorescent sensing material;

[0082] Fluorescence intensities at 460 nm and 617 nm were measured under ultraviolet light irradiation, and the results were analyzed via F... 617 / F 460 The ratio enables quantitative detection of phosphate.

[0083] In some embodiments, the concentration of the fluorescent sensing material suspension is 1.5-2.5 mg / mL, for example, 1.5 mg / mL, 1.8 mg / mL, 2.0 mg / mL, 2.2 mg / mL, or 2.5 mg / mL. When the probe dispersion concentration is too low, the fluorescence signal is weak, which is not conducive to improving the detection sensitivity; when the probe dispersion concentration is too high, it will lead to increased turbidity of the system or particle aggregation, thereby affecting the accurate acquisition of the fluorescence signal. Therefore, the probe concentration is preferably controlled within the above range.

[0084] In some embodiments, the quantitative detection employs fluorescence spectrophotometry: under ultraviolet light irradiation, the fluorescence intensity of the mixture at 460 nm and 617 nm is measured, and the result is obtained via F... 617 / F 460 The ratio enables quantitative detection of phosphate; the method has a linear detection range of 0-80 μM, a detection limit of 0.48 μM, a response time of 0.3-1.0 min, and maintains an effective response within the pH range of 3-11.

[0085] In some embodiments, the method further includes a visual detection and portable quantification step:

[0086] Under 365 nm ultraviolet light irradiation, the fluorescence color change of the mixed system can be directly observed to achieve visual qualitative or semi-quantitative detection of phosphate;

[0087] Fluorescence images of the system in a darkroom environment were acquired using a smartphone. The red channel value R and the blue channel value B in the images were extracted. Phosphate was quantitatively detected based on the R / B ratio. The linear range of the quantitative detection was 0-80 μM, the response time was 0.3-1.0 min, and it maintained an effective response within the pH range of 3-11.

[0088] In some embodiments, the rapid visual detection method for phosphate can be used to detect phosphate in other water samples such as tap water, lake water, river water, reservoir water, groundwater, aquaculture water, domestic sewage, and industrial wastewater.

[0089] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0090] Example 1

[0091] In one specific embodiment, the present invention provides a method for preparing a self-calibrating dual-channel MOF ratiometric fluorescence sensing material, comprising the following steps: dissolving 2g of 2-methylimidazole in 8 mL of water to obtain a 2-methylimidazole aqueous solution. Separately, dissolving 2mg of 9-AA in 1.25mL of methanol, and simultaneously dissolving 200mg of Zn(NO3)2·6H2O and 100mg of Eu(NO3)3·6H2O in 2mL of water respectively to obtain the corresponding metal salt solutions. Mixing the above Zn(NO3)2·6H2O solution, Eu(NO3)3·6H2O solution, and 9-AA solution, stirring for 3 min, then adding the 2-methylimidazole aqueous solution dropwise to the above mixture, and continuing stirring at room temperature for 30 min. After the reaction is complete, collecting the resulting suspension by centrifugation, washing with water and ethanol sequentially, and drying to obtain 9-AA@Eu-ZIF-8. Subsequently, 50.0 mg of 9-AA@Eu-ZIF-8 was dispersed in 30 mL of ethanol, 20 mg of TTA was added, and the mixture was stirred at room temperature for 20 min. Then, it was centrifuged, washed, and dried to obtain 9-AA@Eu-ZIF-8@TTA.

[0092] Using ZIF-8 as a porous framework, Eu is introduced into the framework. 3+ Forming coordinable luminescent sites; confining 9-AA within the pores as an internal reference channel insensitive to phosphate; and then using TTA to target Eu. 3+ Post-modification coordination was performed to construct a response channel that could competitively coordinate with phosphate; when phosphate was present, the red light channel selectively decayed while the blue light intrinsic parameter remained stable, thus achieving ratiometric self-calibrating detection, such as... Figure 1 As shown.

[0093] Actual test

[0094] To verify the retention of the framework crystal form during stepwise assembly and confirm the successful introduction of 9-AA and TTA, PXRD, FT-IR, and UV-Vis were used to compare and characterize the products obtained in Example 1. The results showed that the PXRD diffraction peaks of ZIF-8, Eu-ZIF-8, 9-AA@Eu-ZIF-8, and 9-AA@Eu-ZIF-8@TTA were basically consistent, indicating that Eu-AA and TTA were successfully introduced. 3+ Doping, 9-AA confinement, and TTA post-modification did not disrupt the ZIF-8 host crystal structure. Figure 2 a); Simultaneously, a new characteristic absorption peak related to TTA appeared in the FT-IR spectrum, accompanied by a change in peak position, and the UV-vis spectrum showed absorption characteristics related to the introduction of 9-AA and TTA, indicating that the component had been successfully introduced ( Figure 2 b). Furthermore, the Eu spectrum was confirmed using XPS total spectrum and high-resolution spectra such as Eu 3d, F 1s, and S 2p. 3+The presence of TTA characteristic elements proves the formation of post-modification coordination, such as Figure 3 As shown. Furthermore, elemental mapping using TEM and EDS revealed that the material maintained a polyhedral morphology, and that elements such as Zn, Eu, C, N, F, and S were uniformly distributed, further confirming the uniformity and reproducibility of the material preparation. Figure 4 As shown.

[0095] To demonstrate that the self-calibrated dual-channel MOF ratiometric fluorescence sensing material of this invention can generate dual-channel emission under a single excitation condition, 9-AA solution ( Figure 5 a), 9-AA@Eu-ZIF-8 ( Figure 5 b), Eu-ZIF-8@TTA ( Figure 5 c) and 9-AA@Eu-ZIF-8@TTA ( Figure 5 d) Three-dimensional fluorescence spectroscopy (3D-EEM) comparative analysis was performed. The results showed that the probe of the present invention has both blue light emission (about 460 nm) and red light emission (about 617 nm), and both can be effectively read out under single-wavelength excitation at 365 nm, indicating that the system is suitable for on-site detection under portable ultraviolet light source conditions.

[0096] Example 2

[0097] Fluorescence ratio detection and quantification performance of phosphate.

[0098] (1) System configuration

[0099] Prepare a 1 mM phosphate stock solution using deionized water. Weigh 4.0 mg of 9-AA@Eu-ZIF-8@TTA and add it to 2.0 mL of deionized water. Sonicate for 5 min to form a homogeneous suspension. The concentration of 9-AA@Eu-ZIF-8@TTA is approximately 2.0 mg / mL.

[0100] (2) Detection steps

[0101] The suspension was transferred to a 1 cm quartz cuvette, and Pi standard solutions of different concentrations were added and mixed thoroughly. After standing for about 0.5 min to equilibrate, fluorescence spectroscopy was then performed.

[0102] The fluorescence testing conditions were as follows: Fluorescence detection was performed using an F-7000 fluorescence spectrophotometer; the excitation wavelength was 365 nm; the emission spectral scanning range was 380-700 nm; the testing temperature was 25±2 ℃; the excitation slit was 5 nm; and the emission slit was 5 nm. Changes in the fluorescence emission signal of 9-AA@Eu-ZIF-8@TTA were observed after adding different concentrations of phosphate. The emission intensity was read at 460 nm (internal reference) and 617 nm (response), and the ratio signal F was calculated. 617 / F 460This establishes a quantitative relationship between phosphate concentration and fluorescence response.

[0103] With F 617 / F 460 A calibration curve was established with respect to the Pi concentration, and the Pi concentration of the unknown sample was determined accordingly. The system exhibits the following behavior: as the Pi concentration increases, the 617 nm red light gradually decreases while the 460 nm light remains essentially unchanged, thus achieving a stable ratioistic response.

[0104] It should be noted that effective detection can be achieved with a fluorescent sensing material suspension concentration of 1.5-2.5 mg / mL, an ultrasonic time of 3-10 min, a settling time of 0.3-1.0 min, an excitation wavelength of 350-380 nm, and an emission scanning range of 380-700 nm. The above specific parameters are only preferred conditions for this embodiment and are not absolute limitations on the detection conditions of this invention.

[0105] In addition, the settling time has a certain impact on the detection results. If the settling time is too short, the interaction between the probe and the analyte is insufficient, making it difficult to obtain a stable fluorescence response; if the settling time is too long, it will prolong the detection cycle and reduce the detection efficiency. Therefore, the settling time is preferably controlled within the range of 0.3-1.0 min.

[0106] (3) Results and performance

[0107] like Figure 6 As shown in Figure a, the 9-AA@Eu-ZIF-8@TTA sensing material exhibits dual emission fluorescence characteristics under 365 nm excitation: the stable internal reference fluorescence peak of 9-AA is at 460 nm, and the fluorescence peak of Eu is at 617 nm. 3+ Characteristic fluorescence response peaks; as the Pi concentration increases from 0 μM to 105 μM, Eu at 617 nm... 3+ The characteristic fluorescence intensity exhibits gradient quenching with increasing Pi concentration, while the fluorescence intensity of the internal reference at 460 nm remains essentially constant. Simultaneously, the system fluorescence color gradually changes from bright red to blue, enabling rapid and visual detection of Pi. As the Pi concentration increases, the Eu at 617 nm... 3+ The red emission gradually decreases, while the blue emission of 9-AA at 460 nm remains basically stable. Figure 6 (b) This indicates that Pi primarily affects the response channel while having a relatively small impact on the intrinsic parameter channel. For example... Figure 6 As shown in c, the F of the sensing material of the present invention 617 / F 460 The ratio fluorescence signal showed a strong linear negative correlation with phosphate concentration. Within the concentration range of 0-80 μM, the linear correlation coefficient R was high. 2The concentration reached 0.992, indicating that the 9-AA@Eu-ZIF-8@TTA material constructed in this invention can achieve accurate and stable quantitative detection of phosphate within the above concentration range, providing a reliable calibration basis and methodological support for rapid on-site quantitative analysis of phosphate in actual samples such as environmental water samples. Furthermore, Figure 6 Figure d shows the color coordinate changes of the 9-AA@Eu-ZIF-8@TTA material of the present invention under different phosphate concentrations. The color coordinates in the figure are determined by the relative intensity of the emission from the 460 nm and 617 nm dual channels. As the phosphate concentration increases, the color coordinates gradually shift from the red region to the blue region, showing a continuous and distinguishable color change. This indicates that the present invention can achieve visualized quantitative detection of phosphate through visual observation or mobile phone RGB analysis.

[0108] Example 3

[0109] The selectivity and anti-interference performance of the probe to phosphate were tested.

[0110] To evaluate the selectivity and anti-interference performance of 9-AA@Eu-ZIF-8@TTA for phosphate, the effects of various possible coexisting ions on the probe ratio fluorescence signal were investigated. The interfering substances tested included Zn. 2+ Ni 2+ K + Na + Mg 2+ Cu 2+ Co 2+ Al 3+ Fe 3+ HCO3 - SO4 2- CO3 2- NO 3- , Br - I - S 2- and citrate.

[0111] The specific testing method is as follows: Take the 9-AA@Eu-ZIF-8@TTA probe suspension prepared in this invention, add each of the above-mentioned single interfering substances respectively, measure its fluorescence emission spectrum under the same detection conditions, and record the fluorescence intensity at 617 nm and 460 nm, and calculate the ratio fluorescence signal F. 617 / F 460 The results showed that among the various metal ions, inorganic anions, and organic anions tested, only the addition of phosphate could induce the probe ratio fluorescence signal F. 617 / F 460 Significant changes occurred, while other ions only caused minor fluctuations or had virtually no significant effect, indicating that the probe of this invention has good selectivity for phosphates. Figure 7 As shown in b.

[0112] To further verify the probe's anti-interference capability, phosphate was added to systems containing the aforementioned interfering ions, and the ratiometric fluorescence response of the probe was measured under the same conditions. The results showed that even in the presence of the aforementioned coexisting ions, the probe could still produce a ratiometric fluorescence response essentially consistent with that when detecting phosphate alone after the addition of phosphate. This indicates that the probe of the present invention still possesses good anti-interference capability and reliable detection performance in complex ionic environments. Figure 7 As shown in b.

[0113] The reason why the probe of this invention exhibits excellent selectivity for phosphates is that phosphates, as relatively strong Lewis bases, can react with Eu in the probe. 3+ Strong Lewis acid-base interactions occur at the site, thus preferentially binding with Eu. 3+ Competition for coordination occurs, and the original coordination site in Eu is partially replaced. 3+ The TTA ligand on the probe induces a characteristic ratiometric fluorescence response. In contrast, although citrate and carbonate ions can also coordinate with lanthanide ions under certain conditions, under the experimental conditions of this invention, their interaction with Eu... 3+ The interaction between them is weak, and their coordination competition ability is insufficient, making it difficult to effectively disrupt Eu. 3+ -TTA coordination environment, therefore it does not cause obvious changes in fluorescence signal.

[0114] Example 4

[0115] Visual detection and mobile phone RGB reading.

[0116] 4.0 mg of 9-AA@Eu-ZIF-8@TTA prepared in this invention was dispersed in 2.0 mL of deionized water and sonicated for 5 min to obtain a uniform suspension. Different concentrations of phosphate standard solutions were added to this suspension, mixed thoroughly, and allowed to stand for 0.5 min. Each sample was photographed and recorded under 365 nm UV light irradiation. RGB readings were taken using the rear camera of a smartphone, at a distance of 10 cm, under 365 nm UV light irradiation conditions in a dark room. The obtained luminescence images were imported into color analysis software to extract the red channel intensity value (R) and blue channel intensity value (B) from each sample image, and the R / B ratio was calculated. A standard relationship curve between phosphate concentration and color parameters was established by plotting the R / B ratio on the ordinate and phosphate concentration on the abscissa. The results showed that the R / B value and Pi concentration met a good linear relationship: R / B = 2.381(0.029[Pi]), R² = 0.98, where [Pi] is the concentration of Pi in μM. Figure 7 As shown in a.

[0117] It should be noted that the R / B ratio is the ratio of the gray value of the red channel to the gray value of the blue channel in the fluorescence image, and is used to characterize the dual-channel fluorescence response of the system.

[0118] The above results show that the 9-AA@Eu-ZIF-8@TTA probe prepared in this invention can not only detect phosphate by fluorescence spectroscopy, but also identify and analyze fluorescence color changes with the help of a smartphone, realizing rapid on-site detection without the need for large instruments.

[0119] Example 5

[0120] Detection of phosphates in actual samples.

[0121] To evaluate the feasibility of applying the 9-AA@Eu-ZIF-8@TTA probe prepared in this invention to actual samples, spiked recovery experiments were conducted on tap water and lake water samples. The tap water was taken from the laboratory water supply system, and the lake water was taken from Baigui Lake in Pingdingshan City, Henan Province.

[0122] Before testing, the actual water samples were filtered through 0.22 μm microporous membranes to remove suspended particles and impurities. Then, phosphate standard solutions of different concentrations were added to the filtered water samples to prepare spiked samples. Each spiked sample was measured under the same fluorescence detection conditions as in Example 2, with each group of samples measured in parallel five times. The phosphate concentration in the samples was calculated based on a pre-established standard curve.

[0123] Table 1 shows the detection results of phosphorus in the actual samples.

[0124] Table 1

[0125]

[0126] a This is the average value;

[0127] b Not detected.

[0128] As shown in Table 1, the spiked recoveries in tap water and lake water samples were approximately 97.0%-103.2%, and the relative standard deviation (RSD) was less than 4.27%, indicating that the method of the present invention has good accuracy and reliability in real water samples.

[0129] The above results demonstrate that the 9-AA@Eu-ZIF-8@TTA probe prepared in this invention is suitable for rapid detection of phosphates in tap water and lake water. For other environmental water samples, such as river water, reservoir water, groundwater, aquaculture water, domestic sewage, and industrial wastewater, pretreatment methods such as filtration, centrifugation, settling, or appropriate dilution can be used before detection, depending on the complexity of the sample matrix. Its specific applicability can be further verified through actual sample experiments.

[0130] Example 6

[0131] Mechanism verification—Pi competition coordination leads to the interruption of TTA antenna effect

[0132] After adding excess Pi to the 9-AA@Eu-ZIF-8@TTA system, structural and spectroscopic analyses were performed on the material. The results showed that the PXRD patterns remained essentially unchanged before and after the addition of Pi, indicating that the ZIF-8 framework remained intact. In FT-IR, the addition of phosphate resulted in changes at approximately 1000-1100 cm⁻¹. -1 The appearance of a new absorption peak at this point is attributed to the stretching vibration of the PO bond, proving the interaction between phosphate and Eu. 3+ Coordination occurred; simultaneously, the intensity of characteristic absorption peaks associated with TTA coordination (such as C=O, CF, and Eu-O) significantly decreased, indicating that the original Eu... 3+ - The TTA coordination structure was partially disrupted; the F 1s and S 2p signals associated with TTA in XPS were significantly weakened or disappeared, while the intrinsic elements of the framework remained, indicating that Pi and Eu were related. 3+ Competition for coordination occurs and the original TTA ligand is replaced, such as... Figure 8 As shown.

[0133] Furthermore, TEM-EDS elemental mapping results showed that P element signals appeared in the material after the addition of Pi, and the spatial distributions of P and Eu elements overlapped, supporting the correlation between Pi and Eu. 3+ Determining site binding, such as Figure 9 As shown.

[0134] Furthermore, time-resolved fluorescence lifetime tests showed that the fluorescence lifetimes at 460 nm and 617 nm did not change significantly before and after the addition of phosphate, indicating that the response mechanism of this invention does not involve dynamic quenching processes such as fluorescence resonance energy transfer (FRET) or photoinduced electron transfer (PET). Figure 10 As shown. Combined with FT-IR and XPS analysis, it was confirmed that phosphate replaces the TTA ligand through competitive coordination, leading to the interruption of the antenna effect, which belongs to the quenching mechanism caused by changes in the static coordination environment.

[0135] It should be noted that the antenna effect refers to the process by which the TTA absorbs external excitation energy and transfers it to Eu. 3+This will enhance Eu 3+ The process of red launch.

[0136] To further demonstrate the morphology of the main framework, system dispersibility, single-wavelength excitation adaptability, response kinetics, wide pH applicability, and long-term storage stability, the following supplementary characterization was performed on the 9-AA@Eu-ZIF-8@TTA of this invention:

[0137] (1) Complex particle size distribution (DLS) test, such as Figure 11 The diagram illustrates particle size and dispersibility.

[0138] (2) Comparison of excitation and emission spectra of 9-AA@Eu-ZIF-8, such as Figure 12 As shown, this illustrates that 365 nm single-wavelength excitation can simultaneously read out both blue and red light channels. Specifically, under 365 nm excitation, 9-AA@Eu-ZIF-8 only exhibits blue emission at 460 nm, while the TTA-modified material exhibits both blue emission at 460 nm and red emission at 620 nm, indicating that TTA successfully coordinated and sensitized Eu. 3+ It produces red fluorescence; the emission spectrum shows that 9-AA@Eu-ZIF-8@TTA exhibits two well-separated characteristic emission peaks at 460 nm and 620 nm, corresponding to 9-AA and Eu, respectively. 3+ The characteristic fluorescence provides an optical basis for dual-channel ratiometric fluorescence detection.

[0139] (3) Comparison of photographs of each material under visible light and 365 nm ultraviolet irradiation, such as Figure 13 As shown; under visible light, Eu-ZIF-8 appears white, while 9-AA@Eu-ZIF-8 loaded with 9-AA and 9-AA@Eu-ZIF-8@TTA modified with TTA appear pale yellow, indicating successful loading of 9-AA. Under 365 nm UV light irradiation, Eu-ZIF-8 shows no obvious fluorescence, while 9-AA@Eu-ZIF-8 exhibits blue fluorescence, confirming successful confinement of 9-AA within the pores; 9-AA@Eu-ZIF-8@TTA modified with TTA exhibits red / orange-red fluorescence, indicating that TTA and Eu-AA react effectively. 3+ Successful coordination and the establishment of the antenna effect enabled Eu 3+ The red emission is dominant. These results directly demonstrate the successful construction of the probe material of this invention and provide a basis for its visualization and detection under ultraviolet light.

[0140] (4) Under specific Pi concentration conditions, F 617 / F 460 Curves of change over time, such as Figure 14As shown, the ratio signal rapidly decreased and stabilized within about 0.5 minutes after the addition of phosphate, and then remained constant, indicating that the probe of the present invention has a rapid response, is suitable for rapid on-site detection, and the detection results have good stability.

[0141] (5) Fluorescence response results under different pH conditions, such as Figure 15 As shown, the results indicate that the ratio fluorescence signal of 9-AA@Eu-ZIF-8@TTA remains stable within the pH range of 3-11. Therefore, the probe of this invention is suitable for water sample detection within the pH range of 3-11 and has wide pH adaptability.

[0142] (6) Continuous multi-day luminescence stability test: The prepared 9-AA@Eu-ZIF-8@TTA probe was stored under the same storage conditions, and samples were taken from day 1 to day 7, and its ratio fluorescence signal F was measured under the same detection conditions. 617 / F 460 The results showed that the ratiometric fluorescence signal of the 9-AA@Eu-ZIF-8@TTA probe prepared in this invention remained basically stable during the 7-day testing period, with no significant attenuation and only slight fluctuations. This indicates that the material has good storage stability and luminescence stability. Figure 16 As shown.

[0143] Comparative Example 1:

[0144] Zhang et al. constructed a CDs / Zn-TCPP (BPDC) ratiometric fluorescent probe for Pi detection, the mechanism of which mainly depends on the interaction between Pi and Zn. 2+ Strong coordination leads to the collapse of the MOF layered structure and the release of TCPP monomers, resulting in fluorescence changes. This material needs to be synthesized in a DMF system by heating at 150 °C, and the detection requires an incubation of about 9 min (YX Zhang, B. Ren, W. Dong, Q. Duan, T. Fei. A ratiometric fluorescence probe based on porphyrin-based MOF for phosphate ions detection. Microchemical Journal, 2025, 211, 113156).

[0145] Comparative analysis: While this scheme can achieve a ratio response, it is a structurally destructive signal source characterized by "skeleton collapse / release," the process relies on high-temperature organic solvents, and structural damage easily affects long-term stability and consistency in repeated detections. This invention employs an "internal reference luminescent component + Eu" approach. 3+The self-calibrating dual-channel strategy of the "-TTA response channel" can stably output ratio signals and visualize color changes without relying on MOF collapse, which is more conducive to reliable readings in the field.

[0146] Comparative Example 2:

[0147] Liu et al. encapsulated carbon dots and gold nanoclusters in ZIF-8 to form CDs / AuNCs@ZIF-8 ratio probes. The Pi response mechanism was that Pi induced the decomposition of ZIF-8 and released the guest, resulting in a change in the ratio signal. The linear range was 1-120 μM, and the detection time was about 10 min (J. Liu, Y. Liu, W. Wang, S. Zhang, L. Tang, P. Ma, D. Song, Q. Fei. Aratiometric fluorescent sensor for the detection of phosphate. Luminescence, 2023, 38, 152–158. DOI: 10.1002 / bio.4434).

[0148] Comparative analysis: This method, like others, belongs to the "framework decomposition / guest release" route. Changes in particle state, turbidity, and the release process can easily introduce fluctuations in on-site readings and negatively impact repeatability and storage stability. This invention utilizes Pi to target Eu... 3+ Competitive coordination enables selective control of the Eu-TTA channel, ensuring stable internal standard signals and avoiding the uncertainties caused by "decomposition-release".

[0149] Comparative Example 3:

[0150] Zhang et al. proposed a two-stage stimuli-responsive probe for PMOF@Al2O3: first, the Al2O3 protective layer is destroyed, and then PMOF is further destroyed to release TCPP and generate a fluorescent signal. Its preparation involves multiple solvothermal / post-modification steps: 2D Zr-BTB needs to be synthesized in DMF at 120°C for 48 h, TCPP assembly needs to be done at 100°C for 12 h, and Al2O3 regeneration needs to be done at 90°C for 4 h; the detection incubation is about 10 min (G.Zhang, Y. Ma, H. Chai, K. Yu, Y. Li, S. Wang, J. Ma, L. Qu, W. Tan, X. Zhang. Porphyrinic metal–organic framework@alumina nanocomposite fluorescent probe: two-stage stimuli-responsive behavior and phosphate sensing. Sensors and Actuators B: Chemical, 2022, 370, 132395).

[0151] Comparative analysis: This system involves multiple steps, is time-consuming, and relies on high-temperature organic solvents. Furthermore, the response mechanism essentially still involves protective layer destruction and framework collapse / release, limiting its field consistency and long-term stability. This invention, through modular construction of a dual-channel probe, avoids damage to the chain caused by multi-layered structures, resulting in more direct and controllable readings.

[0152] Comparative Example 4:

[0153] Gao et al. constructed an RhB@UiO-66-NH2 ratio probe, where RhB was the reference signal and UiO-66-NH2 was the response signal; PO4 3-The interaction with Zr-O nodes weakens the LMCT process, enhancing MOF emission recovery and enabling ratiometric detection with a linear range of 80-400 μM and a LOD of approximately 2.0 μM. However, solution detection requires 2 h of incubation, and immobilization in hydrogels still requires approximately 1 h of incubation. Furthermore, the synthesis of UiO-66-NH2 requires a solvothermal reaction at 120 °C for 48 h (N. Gao, J. Huang, L. Wang, J. Feng, P. Huang, F. Wu. Ratiometric fluorescence detection of phosphate in human serum with a metal-organic frameworks-based nanocomposite and its immobilized agarosehydrogels. Applied Surface Science, 2018, 459, 686–692).

[0154] Comparative analysis: Although this system has a reference signal, its response time is on the order of hours and its linear range is relatively high, which is not conducive to low-concentration, rapid on-site monitoring. This invention is based on the competitive coordination rapid interruption Eu-TTA antenna effect, which has a faster response and can stably perform ratio quantification in the low μM range, which is more suitable for environmental water samples.

[0155] Comparative Example 5:

[0156] Li et al. reported the use of UiO-66(Fe / Zr)-NH2 for Pi ratio detection: the Fe node provides peroxidase-like activity to catalyze the generation of OPD into OPDox (555 nm), and quenches the intrinsic emission of MOFs (435 nm) through an internal filtration effect; after Pi adsorbs onto the Zr-O site, it inhibits the enzyme-like activity, reducing OPDox generation and achieving I 555 / I 435Ratio response. This method requires a pH 4.0 buffer, and the detection procedure is "incubate with Pi for 5 min, then add H2O2 and react with OPD for 30 min", totaling approximately 35 min; MOF preparation is a DMF system hydrothermal at 120 °C for 12 h (X. Li, P. Liu, X. Niu, K. Ye, L. Ni, D. Du, J. Pan, Y. Lin. Tri-functional Fe–Zr bi-metal–organic frameworks enable high-performance phosphate ion ratiometric fluorescent detection. Nanoscale, 2020, 12, 19383–19389).

[0157] Comparative analysis: This system has high sensitivity, but the detection depends on the added substrate and catalytic process, involving many steps and variables (substrate concentration, H2O2 activity, temperature, etc.), and requires acidic conditions, limiting its on-site repeatability and simplicity. This invention does not rely on added substrates or catalytic scale-up, but only utilizes Pi-Eu... 3+ Competitive coordination enables rapid ratio response, resulting in a simpler system and greater environmental adaptability.

[0158] In summary, this invention constructs an "internal reference luminescent component + Eu" within the same MOF carrier. 3+ A self-calibrated dual-emission system with a "-TTA response channel" and utilizing Pi-Eu 3+ Competition-triggered local antenna replacement enables rapid, stable, wide-environment-applicable, and highly interference-resistant visualization / quantitative detection of phosphates via mobile phones. It overcomes the problems commonly found in existing technologies, such as complex high-temperature solvothermal processes, inconvenience of deep ultraviolet excitation in the field, poor stability due to reliance on frame destruction, slow response due to multiple steps, and insufficient field consistency.

[0159] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A self-calibrating dual-channel MOF ratio fluorescence sensing material, characterized in that, The material includes a main frame, an intrinsic luminescent component, and a responsive luminescent component; The main frame is Eu 3+ The doped ZIF-8 metal-organic framework is denoted as Eu-ZIF-8; The internal reference luminescent component is 9-aminoacridine confined in the Eu-ZIF-8 channels; The responsive luminescent component is 2-thiamethoxytrifluoroacetylacetone and Eu. 3+ The sensitized luminescent center formed by coordination is denoted as Eu. 3+ -TTA.

2. The self-calibrating dual-channel MOF ratio fluorescence sensing material according to claim 1, characterized in that, The material simultaneously produces blue and red dual-channel fluorescence emission under single-wavelength excitation.

3. The method for preparing a self-calibrating dual-channel MOF ratio fluorescence sensing material according to claim 1, characterized in that, Includes the following steps: The first step involves mixing 9-aminoacridine solution, zinc salt solution, and Eu... 3+ After mixing the salt solutions, they were reacted with 2-methylimidazole solution at room temperature to give 9-AA@Eu-ZIF-8; In the second step, 9-AA@Eu-ZIF-8 was dispersed in ethanol, and 2-thiamethoxyacetylacetone was added to carry out a coordination reaction to obtain 9-AA@Eu-ZIF-8@TTA.

4. The preparation method according to claim 3, characterized in that, The zinc salt solution is a zinc nitrate solution, and the Eu... 3+ The salt solution is a europium nitrate solution.

5. The preparation method according to claim 4, characterized in that, The concentration of the 9-aminoacridine solution is 0.5-6.0 mg / mL, the concentration of the 2-methylimidazole solution is 0.15-0.417 g / mL, the concentration of the zinc nitrate solution is 50-250 mg / mL, and the concentration of the europium nitrate solution is 26.67-120 mg / mL.

6. The preparation method according to claim 3, characterized in that, The mass ratio of 2-thiayltrifluoroacetylacetone to 9-AA@Eu-ZIF-8 powder is (0.1-0.5):

1.

7. A method for rapid visual detection of phosphate using the self-calibrated dual-channel MOF ratio fluorescence sensing material according to any one of claims 1 to 6, characterized in that, Includes the following steps: Mix the sample to be tested with the suspension of the fluorescent sensing material and let it stand until the response equilibrium is reached; Qualitative or quantitative detection of phosphates can be achieved by detecting the ratio of dual-channel fluorescence signals in a mixed system under ultraviolet light excitation.

8. The method for rapid visual detection of phosphate according to claim 7, characterized in that, The quantitative detection was performed using fluorescence spectrophotometry: under ultraviolet light irradiation, the fluorescence intensity of the mixture at 460 nm and 617 nm was measured, and the result was analyzed via F... 617 / F 460 The ratio enables quantitative detection of phosphate; the method has a linear detection range of 0-80 μM, a detection limit of 0.48 μM, a response time of 0.3-1.0 min, and maintains an effective response within the pH range of 3-11.

9. The method for rapid visual detection of phosphate according to claim 7, characterized in that, The method also includes visual detection and portable quantification steps: Under 365 nm ultraviolet light irradiation, the fluorescence color change of the mixed system can be directly observed to achieve visual qualitative or semi-quantitative detection of phosphate; Fluorescence images of the system in a darkroom environment were acquired using a smartphone. The red channel value R and the blue channel value B in the images were extracted. Phosphate was quantitatively detected based on the R / B ratio. The linear range of the quantitative detection was 0-80 μM, the response time was 0.3-1.0 min, and it maintained an effective response within the pH range of 3-11.

Images