A porphyrin-based Al-MOF material, a preparation method and application thereof

Abstract

The application discloses a kind of based on porphyrin Al-MOF material, the based on porphyrin Al-MOF material is presented by multiple layers nanometer sheet stacking into shuttle columnar shape shuttle columnar shape.The application also discloses the preparation method of the above-mentioned based on porphyrin Al-MOF material and its application in ratio type fluorescent sensor.The application also discloses a kind of ratio type fluorescent sensor, the ratio type fluorescent sensor is the solution containing the above-mentioned based on porphyrin Al-MOF material, the pH of solution is 7.3-7.5.The application also discloses a kind of method for detecting copper ion.The based on porphyrin Al-MOF material of the application has unique microstructure, it is used as ratio type fluorescent sensor and can realize specific identification to copper ion, and sensitivity is high, anti-interference ability is good, stability is good;And the preparation method of the application is simple, easy to operate, time consumption is shorter.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fluorescent sensing technology, and in particular to a kind of Al-MOF material based on porphyrin and its preparation method and application. BACKGROUND

[0002] Copper is a metal element widely present in nature, and is an essential trace element for human health and plant and animal growth. However, excessive intake of Cu 2+ can cause a series of adverse health effects such as vomiting, diarrhea, stomach discomfort, and even severe liver and kidney damage. Due to the widespread use of Cu 2+ in households, industries and agriculture, it can accumulate in water, plants and animals in the food chain, leading to contamination of drinking water and agriculture-related substrates such as tea, thereby having physiological effects on humans. In order to meet the needs of environmental monitoring and food safety evaluation, it is of great significance to develop a highly efficient, selective and sensitive Cu 2+ detection method for human health and environmental protection.

[0003] Currently, the main methods for detecting Cu 2+ include inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectrometry (ICP-AES), electrochemical method, fluorescence method, etc. Among them, fluorescence method is of great concern due to its unique advantages such as high sensitivity, good selectivity, fast speed, inexpensive equipment and simple operation. Currently, in order to facilitate the measurement of trace Cu 2+ , a variety of types of fluorescent sensors have been synthesized, but most of them can only achieve single-color fluorescence detection, with inherent instability and environmental interference. In contrast, due to the self-calibration mechanism, ratio fluorescent sensors are considered as potential candidates.

[0004] Metal-organic frameworks (MOFs) are composed of organic struts and inorganic nodes, and have attracted extensive research interest due to their potential application prospects, especially in gas storage and separation, catalysis, drug delivery and sensing. In addition, luminescent metal-organic frameworks (LMOFs) have attracted extensive interest in the field of chemical sensors due to their unique chemical and physical properties, including tunable structure, large surface area, ultra-high porosity and thermal and chemical stability.

[0005] Currently, in order to avoid the influence of complex samples and environment and effectively improve the signal accuracy of MOFs-based sensors, many research groups have introduced fluorescent guest materials into the channels or cavities of luminescent MOFs by taking advantage of the inherent porosity and guest binding capacity of luminescent MOFs, forming functionalized composite materials with dual-emission system. However, the formation process of such composite materials requires complex operations and consumes a lot of time. Therefore, it is of great significance to synthesize ratio-type fluorescent sensors with a simple method. SUMMARY

[0006] Based on the technical problems existing in the background art, the application provides a porphyrin-based Al-MOF material and a preparation method and application thereof; the porphyrin-based Al-MOF material has a unique microstructure, and when used as a ratio-type fluorescent sensor, can realize specific recognition of copper ions, has high sensitivity, good anti-interference ability and good stability; and the preparation method is simple, easy to operate and short in time consumption.

[0007] The application provides a porphyrin-based Al-MOF material, which is in a shuttle column shape and is stacked by multiple layers of nanosheets into a shuttle column shape.

[0008] Preferably, the average thickness of the nanosheet is 14-24 nm.

[0009] Preferably, the length of the shuttle column is 1-4 μm; more preferably, the length of the shuttle column is 2-3 μm.

[0010] The porphyrin-based Al-MOF material has a unique microstructure, and Al 3+ in the porphyrin-based Al-MOF material is not coordinated with pyrrole N in the porphyrin ring, thereby providing a recognition site for ion detection; when used as a ratio-type fluorescent sensor, can realize specific recognition of copper ions, has high sensitivity, can effectively avoid interference from the environment and complex samples, has good anti-interference ability, and has good stability.

[0011] The application further provides a preparation method of the porphyrin-based Al-MOF material, which comprises the following steps: uniformly mixing meso-tetra(4-carboxyphenyl) porphyrin, an aluminum source and water, and performing hydrothermal reaction to obtain the porphyrin-based Al-MOF material.

[0012] Preferably, the aluminum source is a water-soluble aluminum salt.

[0013] Preferably, the aluminum source is at least one of aluminum chloride trihydrate and aluminum chloride.

[0014] Preferably, the weight ratio of the meso-tetra(4-carboxyphenyl) porphyrin to water is 0.1:1-2.

[0015] Preferably, the molar ratio of the meso-tetra(4-carboxyphenyl) porphyrin to Al 3+ is 1:1.8-2.2.

[0016] Preferably, the temperature of the hydrothermal reaction is 175-185 ℃, and the time is 16-24 h.

[0017] Preferably, after the hydrothermal reaction, solid-liquid separation, washing, and drying, the porphyrin-based Al-MOF material is obtained.

[0018] For metal organic framework materials, different raw materials, dosages, preparation steps, and process parameters can cause significant differences in the microstructure of the materials. The present application obtains the specific structure of the porphyrin-based Al-MOF material by selecting appropriate raw materials, dosages, and combining appropriate process parameters. Moreover, the preparation method is simple, easy to operate, and time-consuming.

[0019] The present application also provides the application of the porphyrin-based Al-MOF material in a ratiometric fluorescent sensor.

[0020] Preferably, the application is in detecting copper ions in the ratiometric fluorescent sensor.

[0021] The present application also provides a ratiometric fluorescent sensor containing the porphyrin-based Al-MOF material, and the pH of the solution is 7.3-7.5.

[0022] Preferably, the concentration of the porphyrin-based Al-MOF material is 0.05-0.2 mg / mL.

[0023] Preferably, the solvent of the porphyrin-based Al-MOF material solution is one of a HEPES buffer aqueous solution with pH=7.3-7.5 and a Tris-HCl buffer aqueous solution with pH=7.3-7.5.

[0024] The HEPES buffer aqueous solution with pH=7.3-7.5 is an N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid aqueous solution, and the pH is adjusted to 7.3-7.5 by using an aqueous hydrochloric acid solution.

[0025] The HEPES buffer aqueous solution and the Tris-HCl buffer aqueous solution can maintain a stable pH range when the ratiometric fluorescent sensor detects ions, thereby avoiding the influence of pH value changes on the fluorescence intensity and further affecting the detection results.

[0026] The present application also provides a method for detecting copper ions, which comprises the following steps: using a fluorescence spectrophotometric method, adding a to-be-detected solution into the ratiometric fluorescent sensor, and detecting the fluorescence intensity.

[0027] The above-mentioned water is deionized water.

[0028] Advantages:

[0029] The porphyrin-based Al-MOF material has a unique microstructure, and the Al 3+The pyrrole N in the porphyrin ring is not coordinated, which provides a recognition site for ion detection, and the porphyrin itself has a dual-emission characteristic, so that the use of the single-component ratio fluorescent sensor can realize specific recognition of copper ions, and the sensitivity is high, and the detection limit is 5.28nM (the known existing fluorescent sensor Cu 2+ The detection limit is generally 32.4nM-1mM); the ratio fluorescent sensor system has a self-calibration function, which can effectively avoid the interference of the environment and complex samples, has good anti-interference ability, and has a satisfactory recovery rate and reliability in real water samples and complex tea samples, indicating that the ratio fluorescent sensor has a potential application in the monitoring of Cu 2+ ; and the porphyrin-based Al-MOF material has good stability; and the preparation method is simple, easy to operate, and short in time consumption. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a PXRD diagram of the porphyrin-based Al-MOF material, wherein the experimental value is the porphyrin-based Al-MOF material.

[0031] Figure 2 It is an infrared spectrum diagram of the porphyrin-based Al-MOF material, wherein the Al-MOF is the porphyrin-based Al-MOF material, and the ligand is meso-tetrakis(4-carboxyphenyl) porphyrin.

[0032] Figure 3 It is a scanning electron microscope diagram and nanosheet thickness measurement result of the porphyrin-based Al-MOF material.

[0033] Figure 4 It is an element distribution diagram of the porphyrin-based Al-MOF material.

[0034] Figure 5 It is a fluorescence emission spectrum diagram of the ratio fluorescent sensor of Example 4.

[0035] Figure 6 It is a result diagram of the fluorescence intensity ratio I 467 / I646 of each ion in the ratio fluorescent sensor of Example 4.

[0036] Figure 7 It is a fluorescence response spectrum diagram of the ratio fluorescent sensor of Example 4 to different concentrations of Cu 2+ .

[0037] Figure 8 It is a linear relationship diagram of the fluorescence intensity ratio I 467 / I646 and the concentration of copper ions when the ratio fluorescent sensor of Example 4 detects copper ions.

[0038] Figure 9 Example 4 ratio type fluorescent sensor detects Cu in the presence of other ions 2+ Anti-interference test fluorescent response intensity diagram of Example 4 ratio type fluorescent sensor, wherein ions is no Cu added 2+ ions+Cu 2+ Anti-interference test fluorescent response intensity diagram of Example 4 ratio type fluorescent sensor, wherein ions is no Cu added 2+ . DETAILED DESCRIPTION

[0039] Hereinafter, the technical solutions of the present application will be described in detail through specific examples.

[0040] Example 1

[0041] A preparation method of a porphyrin-based Al-MOF material, comprising the following steps:

[0042] At room temperature, 100 mg (0.126 mmol) of meso-tetra(4-carboxyphenyl) porphyrin and 60 mg (0.25 mmol) of aluminum chloride hexahydrate were weighed, 10 mL of deionized water was measured, the three were mixed and stirred for 30 min, then transferred to a stainless steel reaction kettle containing a polytetrafluoroethylene liner, the temperature was adjusted to 180℃, and the hydrothermal reaction was carried out for 24 h, then cooled to room temperature, centrifuged, the precipitate was washed with DMF to remove unreacted meso-tetra(4-carboxyphenyl) porphyrin, then the precipitate was washed with acetone, and dried in a vacuum drying box overnight, ground, and a brick red powder was obtained, which was the porphyrin-based Al-MOF material.

[0043] The porphyrin-based Al-MOF material prepared in Example 1 was detected, and the results are shown in Figures 1-3 , Figure 1 PXRD diagram of the porphyrin-based Al-MOF material, wherein the experimental value is the porphyrin-based Al-MOF material; Figure 2 Infrared spectrum diagram of the porphyrin-based Al-MOF material, wherein Al-MOF is the porphyrin-based Al-MOF material, and the ligand is meso-tetra(4-carboxyphenyl) porphyrin; Figure 3 Scanning electron microscope diagram and nanosheet thickness measurement results of the porphyrin-based Al-MOF material; Figure 4 Element distribution diagram of the porphyrin-based Al-MOF material.

[0044] It can be seen from Figure 1 that the porphyrin-based Al-MOF material exhibits good phase purity and basically corresponds to the simulated peak (the simulated peak is a simulated XRD standard card).

[0045] It can be seen from Figure 2 that the -COOH in the ligand (meso-tetra(4-carboxyphenyl) porphyrin) is at 1685 cm -1The carbonyl (C=O) stretching vibration at the carbonyl group is severely suppressed in porphyrin-based Al-MOF materials, indicating that the carboxyl group of the ligand in porphyrin-based Al-MOF materials interacts with the Al group. 3+ Coordination occurs; the stretching and in-plane bending vibrations of -NH in the ligand occur at 3315 and 964 cm⁻¹. -1 The two peaks mentioned above, which exhibit strong absorption peaks at the porphyrin-based Al-MOF materials, can also be observed, indicating that Al... 3+ It does not coordinate with the pyrrole N in the porphyrin ring, which provides a recognition site for subsequent ion detection.

[0046] Depend on Figure 3 It can be seen that the porphyrin-based Al-MOF material is a spindle-shaped column, which is formed by stacking many nanosheets. The surface of the spindle column has a multilayer structure. The average thickness of the nanosheets is 18.7±4.7nm, and the length of the spindle column is 1-4μm.

[0047] Depend on Figure 4 It can be seen that the porphyrin-based Al-MOF material contains Al element, indicating that the synthesis of the porphyrin-based Al-MOF material was successful.

[0048] Example 2

[0049] A method for preparing porphyrin-based Al-MOF materials includes the following steps: mixing meso-tetra(4-carboxyphenyl)porphyrin, an aluminum source, and water, and carrying out a hydrothermal reaction to obtain porphyrin-based Al-MOF materials.

[0050] At room temperature, 100 mg (0.126 mmol) of racemic tetra(4-carboxyphenyl)porphyrin and 55 mg (0.227 mmol) of aluminum trichloride hexahydrate were weighed out, and 10 mL of deionized water was added. The mixture was stirred for 30 min and then transferred to a stainless steel reactor with a polytetrafluoroethylene liner. The temperature was adjusted to 185 °C and the hydrothermal reaction was carried out for 16 h. The mixture was then cooled to room temperature, centrifuged, and the precipitate was washed with DMF to remove unreacted racemic tetra(4-carboxyphenyl)porphyrin. The precipitate was then washed with acetone, dried overnight in a vacuum drying oven, and ground to obtain a brick-red powder, which is the porphyrin-based Al-MOF material.

[0051] Example 3

[0052] A method for preparing porphyrin-based Al-MOF materials includes the following steps: mixing meso-tetra(4-carboxyphenyl)porphyrin, an aluminum source, and water, and carrying out a hydrothermal reaction to obtain porphyrin-based Al-MOF materials.

[0053] At room temperature, 100 mg (0.126 mmol) meso-tetra(4-carboxyphenyl) porphyrin and 67 mg (0.278 mmol) aluminum chloride trihydrate were weighed, 12 mL deionized water was measured, the three were mixed and stirred for 30 min, then transferred to a stainless steel reaction kettle with a polytetrafluoroethylene liner, the temperature was adjusted to 175℃, and the hydrothermal reaction was carried out for 24 h, then cooled to room temperature, centrifuged, washed the precipitate with DMF to remove unreacted meso-tetra(4-carboxyphenyl) porphyrin, then washed the precipitate with acetone, dried in a vacuum drying oven overnight, ground, and a brick red powder was obtained, which was a porphyrin-based Al-MOF material.

[0054] Example 4

[0055] A ratio type fluorescent sensor, the preparation steps of which comprise:

[0056] N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid was weighed, deionized water was added and stirred to dissolve; 0.1 mol / L HCl aqueous solution was added dropwise to adjust the pH, and the pH value of the solution was observed with a pH meter to record the reading until the pH was 7.4 to obtain an HEPES buffer aqueous solution, wherein the concentration of HEPES was 20 mmol / L, and the solution was stored in a 4℃ refrigerator for later use.

[0057] The porphyrin-based Al-MOF material prepared in Example 1 was weighed and added into the HEPES buffer aqueous solution, and ultrasonic treatment was performed for 20 min to obtain a uniformly dispersed suspension, which was a ratio type fluorescent sensor, wherein the concentration of the porphyrin-based Al-MOF material was 0.1 mg / mL.

[0058] The ratio type fluorescent sensor prepared in Example 4 was subjected to fluorescence emission spectrum detection, and the results are shown in Figure 5 , Figure 5 which is the fluorescence emission spectrum of the ratio type fluorescent sensor of Example 4.

[0059] As can be seen from Figure 5 , the ratio type fluorescent sensor of Example 4 has two fluorescence emission peaks at 467 nm and 646 nm under excitation at 395 nm.

[0060] Example 5

[0061] The ratio type fluorescent sensor of Example 4 was used to detect common chloride salts MCl x and sodium salts Na x Y (M = Na + , K + , Ni 2+ , Mn 2+ , Al 3+ , Mg 2+ , Zn 2+, Ca 2+ , and Co 2+ ), (Y = Cl-, NO3 - , F - , SO3 2- , Ac - , CO3 2- , NO2 - , and PO4 3- ) were used to carry out fluorescence selective experiments, and the specific steps were as follows:

[0062] Chloride salts and sodium salts were respectively prepared into aqueous solutions with a concentration of 1 x 10 -2 mol / L, 20 μL of the chloride salt and sodium salt aqueous solutions were respectively added into 2 mL of the ratiometric fluorescent sensor of Example 4, and after stirring for 30 s, fluorescence detection was carried out and the fluorescence emission spectrum was recorded, the fluorescence intensity ratio I 467 / I646 of each ion was calculated, and the results are shown in Figure 6 . Figure 6 is a result graph of the fluorescence intensity ratio I 467 / I646 of each ion in the ratiometric fluorescent sensor of Example 4.

[0063] As can be seen from Figure 6 , when and only when Cu 2+ is added, the fluorescence intensity ratio I 467 / I646 of the ratiometric fluorescent sensor of Example 4 is obviously enhanced, while the addition of other salt solutions has little effect on the fluorescence intensity ratio of the sensor.

[0064] Example 6

[0065] The detection ability of the ratiometric fluorescent sensor of Example 4 for copper ions was explored. The specific steps were as follows: 0.1 mmol / L Cu 2+ solution was prepared, and 20 μL of the Cu 2+ solution was added into a quartz tube containing 2.0 mL of the ratiometric fluorescent sensor of Example 4 (a total of 100 μL of Cu 2+ solution was added), after each addition of Cu 2+ solution, the mixture was stirred for 40 s, and then the fluorescence was measured under excitation at 395 nm. The results are shown in Figure 7 . Figure 7 is a fluorescence response spectrum graph of the ratiometric fluorescent sensor of Example 4 to Cu 2+ ions with different concentrations.

[0066] As can be seen from Figure 7 , with the increase of the amount of copper ions, the fluorescence intensity at 646 nm continuously decreases, while the fluorescence intensity at 467 nm is basically unchanged.

[0067] Cu with a concentration of 0.1 mM 2+ The solution was gradually added to a quartz tube containing a 2.0 mL ratiometric fluorescence sensor from Example 4 (20 μL Cu was added each time). 2+ Solution (total 100 μL), Cu added each time. 2+ After dissolving, shake for 40 seconds to mix, then measure the fluorescence intensity under 395 nm excitation, and examine the fluorescence intensity ratio I. 467 / I646 The linear relationship with copper ion concentration is shown in the following results. Figure 8 As shown; Figure 8 In Example 4, when the ratiometric fluorescence sensor detects copper ions, the fluorescence intensity ratio I... 467 / I646 Linear relationship between the concentration of copper ions and the concentration of copper ions.

[0068] Depend on Figure 8 It can be seen that: the fluorescence intensity ratio I 467 / I646 With C Cu2+ The linear relationship between 1 and 5 μM indicates that it can quantitatively detect Cu in water at low concentrations. 2+ Cu can be calculated using the formula LOD = 3σ / k. 2+ The detection limit was 5.28 nM.

[0069] Anti-interference analysis was performed on the ratiometric fluorescence sensor of Example 4. Cu was added in the presence of various other ionic solutions. 2+ The solution was subjected to fluorescence testing. The results are as follows: Figure 9 As shown; Figure 9 Example 4: Ratio-modulated fluorescence sensor for detecting Cu in the presence of other ions. 2+ The fluorescence response intensity diagram of the anti-interference test, where ions represent the fluorescence intensity without Cu. 2+ ions+Cu 2+ Cu was added 2+ .

[0070] Depend on Figure 9 It can be seen that: adding Cu 2+ After solution, the fluorescence intensity ratio I 467 / I646 The significant enhancement indicates that the ratiometric fluorescence sensor of Example 4 can detect Cu 2+ It has good anti-interference performance.

[0071] Example 7

[0072] Tap water, lake water, and two types of tea were selected as samples to investigate the potential application of the ratiometric fluorescence sensor in Example 4 in a real-world environment. The specific steps are as follows:

[0073] Two types of water samples were selected: laboratory tap water and lake water (from Anhui University). Two types of tea samples were selected: white tea (from Huzhou, Zhejiang) and green tea (from Huangshan, Anhui) for pretreatment.

[0074] The pretreatment steps were as follows: both water samples were centrifuged and filtered through a 0.2μm microporous membrane to remove impurities, and then set aside for use.

[0075] Two tea samples were dried at 80℃ for 24 hours, ground into powder, and passed through an 80-mesh sieve. Each sample was placed in a 50ml round-bottom flask, and 5ml of nitric acid solution was added. The mixture was heated in an oil bath at 180℃ to decompose the tea. When the mixture in the round-bottom flask was nearly dry and no reddish-brown fumes escaped from the mouth of the flask, 5.0mL of hydrogen peroxide was added to further remove excess nitric acid. After drying and cooling to room temperature, HEPES buffer (pH = 7.4, 0.1M) was added, mixed well, filtered, and the filtrate was collected for later use.

[0076] Cu solutions of different concentrations were prepared using pretreated tap water, lake water, and tea solution. 2+ The solutions were added separately to the ratiometric fluorescence sensor of Example 4. Under 395 nm excitation light, the ratio of the fluorescence emission peak intensities at 467 nm and 646 nm was measured and then incorporated into... Figure 8 The linear regression equation is Y = 0.8109X - 2.0209 (where X is the concentration of copper ions, Y is Ln(I)). 467 / I 646 The concentration of copper ions in the sample was calculated, and the recovery rate was calculated. The results are shown in Table 1.

[0077] Table 1. Results of copper ion detection and recovery in actual water and tea samples.

[0078] Sample Amount added (μΜ) Limit of detection (μΜ) Recovery (%) RSD (%) Tap water 1.0 1.15 115.18 1.22 1.9 1.82 95.64 2.06 2.9 2.82 97.26 2.37 Lake water 1.0 1.15 114.82 5.88 1.9 1.91 100.6 1.03 2.9 2.86 98.62 2.93 White tea White tea 1.0 0.98 98.20 3.02 1.9 1.82 95.80 5.09 2.9 2.84 98.08 2.13 Green tea 1.0 0.95 94.81 3.67 1.9 1.83 96.11 3.45 2.9 2.86 98.54 4.34

[0079] Note: The amounts added and detected in Table 1 refer to Cu. 2+ Amount added, Cu 2+ Detection amount.

[0080] As shown in Table 1, the recoveries of copper ions in the two actual water samples and the two tea samples were 95.64-115.18% and 94.81-98.54%, respectively, with relative standard deviations of 1.03-5.88% and 2.13-5.09%, respectively. This indicates that the porphyrin-based ratiometric fluorescence sensor described in this invention has good accuracy in detecting copper ions in both actual water samples and tea samples, and has good practical performance.

[0081] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A porphyrin-based Al-MOF material, characterized in that, The porphyrin-based Al-MOF material is in a shuttle column shape, stacked by multiple layers of nanosheets into a shuttle column shape. The average thickness of the nanosheet is 14-24 nm, and the length of the shuttle column is 1-4 μm. The preparation method of the porphyrin-based Al-MOF material comprises the following steps: mixing meso-tetra(4-carboxyphenyl) porphyrin, an aluminum source and water, and performing a hydrothermal reaction to obtain the porphyrin-based Al-MOF material. The weight ratio of meso-tetra(4-carboxyphenyl) porphyrin to water is 0.1:10 or 0.1:

12. meso-tetra(4-carboxyphenyl)porphine with Al 3+ in a molar ratio of 1 : 1.8-2.2; The temperature of the hydrothermal reaction is 175-185 ℃, and the time is 16-24 h.

2. A method for preparing a porphyrin-based Al-MOF material according to claim 1, characterized by, The preparation method of the porphyrin-based Al-MOF material comprises the following steps: mixing meso-tetra(4-carboxyphenyl) porphyrin, an aluminum source and water, and performing a hydrothermal reaction to obtain the porphyrin-based Al-MOF material.

3. The method for preparing porphyrin-based Al-MOF materials according to claim 2, characterized in that, The aluminum source is a water-soluble aluminum salt.

4. The method for preparing porphyrin-based Al-MOF materials according to claim 2, characterized in that, The aluminum source is at least one of aluminum chloride hexahydrate and aluminum chloride.

5. The method for preparing porphyrin-based Al-MOF materials according to claim 2, characterized in that, After the hydrothermal reaction, solid-liquid separation, washing and drying are performed to obtain the porphyrin-based Al-MOF material.

6. The porphyrin-based Al-MOF material according to claim 1 is applied in a ratiometric fluorescent sensor.

7. Use according to claim 6, characterized in that, The application in the ratiometric fluorescent sensor for detecting copper ions.

8. A ratiometric fluorescent sensor characterized in that, The ratiometric fluorescent sensor is a solution containing the porphyrin-based Al-MOF material according to claim 1, and the pH of the solution is 7.3-7.

5.

9. The ratiometric fluorescent sensor of claim 8, wherein, The concentration of the porphyrin-based Al-MOF material is 0.05-0.2 mg / mL.

10. The ratiometric fluorescent sensor of claim 8, wherein, The solvent of the solution of the porphyrin-based Al-MOF material is one of a HEPES buffer aqueous solution with pH=7.3-7.5 and a Tris-HCl buffer aqueous solution with pH=7.3-7.

5.

11. A method of detecting copper ions, characterized in that The method comprises the following steps: using a fluorescence spectrophotometry method, adding a to-be-detected solution into the ratiometric fluorescent sensor according to any one of claims 8-10, and detecting the fluorescence intensity.

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