Used to detect Al 3+ Fluorescence-enhanced imine-type covalent organic framework materials, their preparation methods and applications

Abstract

This invention provides a method for detecting Al 3+ A method for preparing a fluorescence-enhanced imine-type covalent organic framework material includes the following steps: Step S1, stirring 2,5-dimethoxy-1,4-dicarboxaldehyde and 1,3,5-trimethylbenzene under water bath heating until uniformly mixed, then adding 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, heating and stirring until uniform, then adding 1,4-dioxane, sonicating, and then adding acetic acid to obtain a first mixture; Step S2, rapidly transferring the first mixture to the lining of a hydrothermal reactor, compacting the reactor, and heating for reaction, after the reaction is completed, removing the pale yellow product from the reactor, soaking it in tetrahydrofuran, and filtering to obtain a second mixture, extracting it with acetone using Soxhlet extraction and vacuum drying to obtain the covalent organic framework material Dma-TAPT. This covalent organic framework material can be used as a fluorescence sensor to detect Al 3+ Highly efficient detection.

Description

Technical Field

[0001] This invention belongs to the field of fluorescent material synthesis, specifically relating to a method for detecting Al. 3+ Fluorescence-enhanced imine-type covalent organic framework materials, their preparation methods, and applications. Background Technology

[0002] Aluminum is the most abundant metal on Earth and is widely used in industrial production. However, excessive aluminum poses significant risks to the environment and human health. Under normal physiological conditions, aluminum readily enters the central nervous system and accumulates in the brain, potentially leading to memory impairment and cognitive disorders, thus contributing to neurotoxicity-based diseases such as Alzheimer's or Parkinson's. Therefore, it is necessary to monitor the levels of aluminum in drinking water and surface water. 3+ By strictly controlling the ions, a highly sensitive and selective Al2O3 ion exchanger can be established. 3+ Detection methods are of great significance to the environment and human health.

[0003] To date, numerous techniques for determining aluminum have been reported, including ICP-MS, neutron activation analysis, atomic absorption spectrometry, high-performance liquid chromatography, and fluorescence methods. Among these methods, fluorescence methods have become highly attractive due to their advantages such as high sensitivity, short response time, convenient detection, and low cost. Although various types of methods for detecting Al have been reported... 3+ A fluorescent chemical sensor, but used for detecting Al 3+ The development of fluorescence sensors still needs further improvement, and a more efficient material needs to be found. Summary of the Invention

[0004] This invention was made to solve the above-mentioned problems, and its purpose is to provide a method for detecting Al. 3+ Fluorescence-enhanced imine-type covalent organic framework materials, their preparation methods, and applications.

[0005] This invention provides a method for detecting Al 3+ The preparation method of the fluorescence-enhanced imine-type covalent organic framework material has the following characteristics and includes the following steps:

[0006] Step S1: Stir 2,5-dimethoxy-1,4-dicarboxaldehyde and 1,3,5-trimethylbenzene under water bath heating until they are mixed evenly. Then add 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, heat and stir evenly, then add 1,4-dioxane, sonicate and add acetic acid to obtain the first mixture.

[0007] Step S2: The first mixture is quickly transferred to the lining of a hydrothermal reactor, the reactor is compressed, and the reaction is heated. After the reaction is completed, the pale yellow product in the reactor is removed, soaked in tetrahydrofuran, and then filtered to obtain the second mixture. The second mixture is extracted with acetone using Soxhlet extraction and then vacuum dried to obtain the covalent organic framework material Dma-TAPT.

[0008] The present invention provides a method for detecting Al. 3+ The preparation method of the fluorescence-enhanced imine covalent organic framework material may also have the following characteristics: in step S1, the temperature during stirring under water bath heating is 40℃, the stirring time is 5min, and the ultrasonic time is 3min.

[0009] The present invention provides a method for detecting Al. 3+ The preparation method of the fluorescence-enhanced imine covalent organic framework material may also have the following characteristics: in step S1, the molar ratio of 2,5-dimethoxy-1,4-dicarboxaldehyde to 2,4,6-tris(4-aminophenyl)-1,3,5-triazine is 2:1 to 1.5.

[0010] The present invention provides a method for detecting Al. 3+ The preparation method of the fluorescence-enhanced imine covalent organic framework material may also have the following characteristics: in step S1, the volume ratio of 1,3,5-trimethylbenzene, 1,4-dioxane and acetic acid is 1:1:2, and the acetic acid is 36% acetic acid.

[0011] The present invention provides a method for detecting Al. 3+ The preparation method of the fluorescence-enhanced imine covalent organic framework material may also have the following feature: in step S2, the amount of the first mixture added does not exceed 30% of the total volume of the hydrothermal reactor.

[0012] The present invention provides a method for detecting Al. 3+ The preparation method of the fluorescence-enhanced imine covalent organic framework material may also have the following characteristics: in step S2, the temperature of the reaction in the oven is 120°C and the reaction time is 72h.

[0013] The present invention provides a method for detecting Al. 3+ The preparation method of the fluorescence-enhanced imine covalent organic framework material may also have the following characteristics: in step S2, after soaking in sufficient tetrahydrofuran for at least 24 hours, a second mixture is obtained by filtration, the second mixture is extracted with acetone by Soxhlet for 24 hours, and then vacuum dried at 80°C for 10 hours.

[0014] The present invention also provides any of the above-mentioned methods for detecting Al. 3+The covalent organic framework material Dma-TAPT was prepared by a method for preparing fluorescence-enhanced imine-type covalent organic framework materials.

[0015] This invention provides the above-mentioned covalent organic framework material Dma-TAPT for detecting Al 3+ Applications in [the context of the text].

[0016] The role and effect of invention

[0017] This invention relates to a fluorescence-enhanced imine-type covalent organic framework material for detecting Al3+, its preparation method, and its application. The invention uses 2,5-dimethoxy-terephthalaldehyde and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine as raw materials to prepare the imine-type covalent organic framework material Dma-TAPT via a solvothermal method. The synthesis conditions of this invention are mild, the raw materials are readily available, and the synthesized covalent organic framework material Dma-TAPT exhibits high purity, easily controllable composition, good uniformity, and strong corrosion resistance.

[0018] Meanwhile, the covalent organic framework material prepared by this invention is a novel porous crystal material, Dma-TAPT, composed of organic structural units connected by covalent bonds. It possesses an adjustable and regular pore structure, high specific surface area, and high chemical and thermal stability. Fluorescent covalent organic framework materials with chelating sites and special spatial structures can, through the chelation effect of active sites on the framework wall, resist Al… 3+ It exhibits highly selective fluorescence response, and is effective against metal interference ions (Cd). 2+ Cr 2+ Mg 2+ Cu 2+ Co 2+ Ni 2+ Pb 2+ 、Sr 2+ and Fe 3+ In the presence of ), the fluorescence intensity did not change significantly, and it was effective against Al. 3+ It has a good identification function.

[0019] Furthermore, the fluorescence intensity of the covalent organic framework material Dma-TAPT prepared in this invention is similar to that of Al. 3+ The concentration exhibits a good linear relationship, with fast response time and good stability. Therefore, the imine-type covalent organic framework material prepared in this invention can be used as a fluorescence sensor to detect Al. 3+ Highly efficient detection. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the reaction of the covalent organic framework material Dma-TAPT in the embodiments of the present invention;

[0021] Figure 2 This is an AA stacked side view of the covalent organic framework material Dma-TAPT in an embodiment of the present invention;

[0022] Figure 3 This is an AA stacked top view of the covalent organic framework material Dma-TAPT in an embodiment of the present invention;

[0023] Figure 4 This is the PXRD pattern of the covalent organic framework material Dma-TAPT in the embodiments of the present invention;

[0024] Figure 5 This is the infrared spectrum of the covalent organic framework material Dma-TAPT in the embodiments of the present invention;

[0025] Figure 6 This refers to the covalent organic framework material Dma-TAPT in the embodiments of the present invention. 13 C NMR spectrum;

[0026] Figure 7 This is the X-ray photoelectron spectrum of the covalent organic framework material Dma-TAPT in the embodiments of the present invention;

[0027] Figure 8 This is a scanning electron microscope image of Dma-TAPT, a covalent organic framework material in an embodiment of the present invention;

[0028] Figure 9 This is a thermogravimetric analysis diagram of the covalent organic framework material Dma-TAPT in the embodiments of the present invention;

[0029] Figure 10 These are the adsorption-desorption isotherms of the covalent organic framework material Dma-TAPT in the embodiments of the present invention;

[0030] Figure 11 These are emission spectra of the covalent organic framework material Dma-TAPT in different solvents in embodiments of the present invention;

[0031] Figure 12 These are the fluorescence emission spectra of the covalent organic framework material Dma-TAPT in different metal ion solutions in the embodiments of the present invention;

[0032] Figure 13 The covalent organic framework material Dma-TAPT and Al in the embodiments of the present invention are 3+ Concentration versus fluorescence emission spectrum intensity curves. Detailed Implementation

[0033] To make the technical means, creative features, objectives and effects of this invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate the fluorescence-enhanced imine covalent organic framework material for detecting Al3+, its preparation method and application.

[0034] <Example>

[0035] This embodiment is used for detecting Al. 3+ The preparation method of the fluorescence-enhanced imine-type covalent organic framework material includes the following steps:

[0036] Step S1: Under water bath heating, stir 2,5-dimethoxy-1,4-dicarboxaldehyde and 1,3,5-trimethylbenzene until homogeneous. Then add 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, heat and stir until homogeneous, then add 1,4-dioxane, sonicate, and then add acetic acid to obtain the first mixture, as follows:

[0037] Add 0.594 g of 2,5-dimethoxy-1,4-dicarboxaldehyde (Dma) and 1 mL of mesitylene to a round-bottom flask, heat and stir in a 40°C water bath for 5 min to mix thoroughly; then add 0.608 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) to the round-bottom flask, heat and stir thoroughly, then add 1 mL of 1,4-dioxane, sonicate for 3 min, and then add 2 mL of 36% acetic acid to obtain the first mixture.

[0038] Step S2: The first mixture is quickly transferred to the lining of a hydrothermal reactor, the reactor is compressed, and the reaction is carried out by heating. After the reaction is completed, the pale yellow product in the reactor is removed, soaked in tetrahydrofuran, and then filtered to obtain the second mixture. The second mixture is then extracted with acetone using a Soxhlet extractor and then vacuum dried to obtain the covalent organic framework material Dma-TAPT. The specific process is as follows:

[0039] The first mixture was quickly transferred to the lining of a hydrothermal reactor, the reactor was compressed, and the mixture was placed in an oven at 120°C for 72 hours. After the reaction was completed, the pale yellow product was removed from the reactor, 30 mL of tetrahydrofuran was added and soaked for 24 hours, and then filtered. The resulting mixture was extracted with acetone using a Soxhlet extractor for 24 hours, and then vacuum dried at 80°C for 10 hours to obtain the covalent organic framework material Dma-TAPT.

[0040] Figure 1 This is a schematic diagram of the reaction of the covalent organic framework material Dma-TAPT in an embodiment of the present invention.

[0041] like Figure 1 As shown, this embodiment is used to detect Al 3+The method for preparing fluorescence-enhanced imine-type covalent organic framework materials uses 2,5-dimethoxyterephthalaldehyde (Dma) and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) as raw materials. The imine-type covalent organic framework material Dma-TAPT is prepared via a solvothermal method, and the stacking diagram is shown below. Figure 2 and Figure 3 As shown, the structural groups in this covalent organic framework (COF) undergo photogenerated electron transfer (PET) processes, leading to a decrease in its fluorescence properties. Al 3+ By interacting with O in Dma-TAPT to form coordination, the PET process in COFs is blocked, resulting in fluorescence enhancement.

[0042] The characterization of the imine-type covalent organic framework material Dma-TAPT prepared in this embodiment is as follows:

[0043] (1) Powder diffraction characterization of phase and crystallization

[0044] Powder diffraction data were collected using a SmartLab 9 X-ray powder diffractometer from Rigaku, Japan.

[0045] Figure 4 This is the PXRD pattern of the covalent organic framework material Dma-TAPT in the embodiments of the present invention.

[0046] like Figure 4 As shown, DMA-TAPT has a strong diffraction peak at 2θ value of 2.73°, which corresponds to the (100) crystal plane of COFs; 4.75°, 5.61° and 7.28° correspond to the (110), (200) and (210) crystal planes, respectively.

[0047] (2) Characterization of structure by infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy

[0048] The infrared spectrum, nuclear magnetic resonance spectrum, and X-ray photoelectron spectrum of Dma-TAPT were analyzed using a Nicolet NEXUS infrared spectrometer (USA), an AVANCE NEO nuclear magnetic resonance spectrometer (Germany), and an Escalab Xi+ X-ray photoelectron spectrometer (Thermo Fisher Scientific, USA).

[0049] Figure 5 This is the infrared spectrum of the covalent organic framework material Dma-TAPT in the embodiments of the present invention; Figure 6 This refers to the covalent organic framework material Dma-TAPT in the embodiments of the present invention. 13 C NMR spectrum; Figure 7 This is the X-ray photoelectron spectrum of Dma-TAPT, a covalent organic framework material in an embodiment of the present invention.

[0050] like Figure 5 As shown, the absorption peaks of the NH group in APT are at 3210, 3324, and 3452 cm⁻¹. -1 The absorption peak of the C=O group of Dma is located at 1679 cm⁻¹. -1 After the reaction, the C=O stretching vibration peak in Dma-TAPT disappeared, and the peak at 1592 cm⁻¹ disappeared. -1 The appearance of a C=N stretching vibration peak indicates that the -NH2 in TAPT reacts with the -CHO in Dma to form an imine via a Schiff base reaction.

[0051] like Figure 6 As shown, the peak at 168 ppm corresponds to the carbon in the triazine ring, 152 ppm corresponds to the carbon in C=N, the peaks at 107 ppm to 127 ppm correspond to the carbon in the benzene ring structural unit, and the peak at 53 ppm corresponds to the carbon in the methoxy group in the side chain.

[0052] like Figure 7 As shown, the peaks with binding energies at 297.9 eV, 409.9 eV, and 544.9 eV are attributed to C1s, N1s, and O1s peaks, respectively.

[0053] (3) Scanning electron microscopy morphology characterization

[0054] The morphology of Dma-TAPT was analyzed using a scanning electron microscope from Zeiss, Germany.

[0055] Figure 8 This is a scanning electron microscope image of Dma-TAPT, a covalent organic framework material in an embodiment of the present invention. Figure 8 The images in the middle are scanning electron microscope images at different magnifications.

[0056] like Figure 8 As shown, the aggregates are formed by the aggregation of tiny rod-shaped fibers.

[0057] (4) Thermogravimetric analysis and adsorption-desorption curves characterize the micropore features.

[0058] Dma-TAPT was characterized using a TA Q600 integrated thermal analyzer (USA) and a MicrotracBEL Belserp max specific surface area and porosity analyzer (Japan).

[0059] Figure 9 This is a thermogravimetric analysis diagram of the covalent organic framework material Dma-TAPT in the embodiments of the present invention; Figure 10 This is the adsorption-desorption isotherm of the covalent organic framework material Dma-TAPT in the embodiments of the present invention.

[0060] like Figure 9As shown, the mass loss before 200℃ is attributed to adsorbed water. The material has high thermal stability and begins to decompose when the temperature is above 380℃.

[0061] like Figure 10 As shown, the adsorption-desorption isotherm curve exhibits a Type IV characteristic, rising rapidly in the low relative pressure region, fully demonstrating the microporous characteristics of the material. The specific surface area is 625.8 m². 2 .g -1 The pore size is mainly distributed at 1.6 nm.

[0062] In this embodiment, the synthesized Dma-TAPT was also dispersed in four solvents—water, acetone, anhydrous ethanol, and tetrahydrofuran—and dispersed to a concentration of 0.5 mg / mL using a high-speed homogenizer. -1 The fluorescence spectrum of the suspension was measured using a fluorescence spectrometer.

[0063] Figure 11 These are emission spectra of the covalent organic framework material Dma-TAPT in different solvents in embodiments of the present invention.

[0064] like Figure 11 As shown, the covalent organic framework material Dma-TAPT achieves the best fluorescence display performance when water is used as the solvent.

[0065] In this embodiment, a solution containing 0.5 mg·mL was also prepared. -1 Dma-TAPT and 1mM nitrate (X(NO3)) n A suspension of ), X = Ca 2+ ,Cr 2+ Ni 2+ Al 3+ Co 2+ ,Fe 3+ Mg 2+ Na + Cd 2+ Cu 2+ Pb 2+ ,Sr 2+ Its fluorescence sensing performance was tested.

[0066] Figure 12 The fluorescence emission spectra of the covalent organic framework material Dma-TAPT in different metal ion solutions are shown in the embodiments of the present invention.

[0067] like Figure 12 As shown, the covalent organic framework material Dma-TAPT, with chelating sites and a special spatial structure, chelates Al through the chelating action of active sites on the framework wall. 3+ It exhibits highly selective fluorescence response, especially when the metal ion is Al. 3+It exhibits optimal fluorescence display performance.

[0068] Therefore, in the presence of metal interfering ions (Cd) 2+ Cr 2+ Mg 2+ Cu 2+ Co 2+ Ni 2+ Pb 2+ 、Sr 2+ and Fe 3+ In the presence of ), the fluorescence intensity of the covalent organic framework material Dma-TAPT does not change significantly, and its effect on Al 3+ It has a good identification function.

[0069] In this embodiment, the synthesized covalent organic framework material Dma-TAPT was also dispersed in water and dispersed to a concentration of 0.5 mg / mL using a high-speed homogenizer. -1 Suspensions of Al(NO3)3 with concentrations of 1, 0.5, 0.25, 0.1, and 0.05 mM were prepared and mixed with COFs suspensions at a 1:1 ratio. The fluorescence emission intensity was measured at an excitation wavelength of 396 nm, and the fluorescence emission intensity was plotted against Al. 3+ Concentration relationship curve.

[0070] Figure 13 The covalent organic framework material Dma-TAPT and Al in the embodiments of the present invention are 3+ Concentration versus fluorescence emission spectrum intensity curves.

[0071] like Figure 13 As shown, Al 3+ At concentrations ranging from 0 mM to 1.0 mM, fluorescence intensity exhibited a linear relationship with aluminum ion concentration. The correlation coefficient was 0.99, and the limit of detection was 1.82 × 10⁻⁶. -5 mol / L.

[0072] The role and effect of the embodiments

[0073] According to the method for detecting Al involved in this embodiment 3+ This embodiment describes the fluorescence-enhanced imine-type covalent organic framework material, its preparation method, and its applications. Using 2,5-dimethoxy-terephthalaldehyde and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine as raw materials, the imine-type covalent organic framework material Dma-TAPT was prepared via a solvothermal method. The synthesis conditions in this embodiment are mild, the raw materials are readily available, and the synthesized covalent organic framework material Dma-TAPT exhibits high purity, easily controllable composition, good uniformity, and strong corrosion resistance.

[0074] Meanwhile, the covalent organic framework material prepared in this embodiment is a novel porous crystal material, Dma-TAPT, composed of organic structural units connected by covalent bonds. It possesses an adjustable and regular pore structure, high specific surface area, and high chemical and thermal stability. Fluorescent covalent organic framework materials with chelating sites and special spatial structures can, through the chelation effect of active sites on the framework wall, resist Al… 3+ It exhibits highly selective fluorescence response, and is effective against metal interference ions (Cd). 2+ Cr 2+ Mg 2+ Cu 2+ Co 2+ Ni 2+ Pb 2+ 、Sr 2+ and Fe 3+ In the presence of ), the fluorescence intensity did not change significantly, and it was effective against Al. 3+ It has a good identification function.

[0075] Furthermore, the fluorescence intensity of the covalent organic framework material Dma-TAPT prepared in this embodiment is similar to that of Al. 3+ The concentration exhibits a good linear relationship, with fast response time and good stability. Therefore, the imine-type covalent organic framework material prepared in this embodiment can be used as a fluorescence sensor to detect Al. 3+ Highly efficient detection.

[0076] The above embodiments are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A method for detecting Al 3+ A method for preparing fluorescence-enhanced imine-type covalent organic framework materials, characterized in that... Includes the following steps: Step S1: Stir 2,5-dimethoxy-1,4-dicarboxaldehyde and 1,3,5-trimethylbenzene under water bath heating until they are mixed evenly. Then add 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, heat and stir evenly, then add 1,4-dioxane, sonicate and add acetic acid to obtain the first mixture. Step S2: The first mixture is quickly transferred to the lining of a hydrothermal reactor, the reactor is compressed, and the reaction is carried out by heating. After the reaction is completed, the pale yellow product in the reactor is removed, soaked in tetrahydrofuran, and then filtered to obtain a second mixture. The second mixture is then extracted with acetone using a Soxhlet extractor and then vacuum dried to obtain the covalent organic framework material Dma-TAPT. In step S1, the molar ratio of 2,5-dimethoxy-1,4-dicarboxaldehyde to 2,4,6-tris(4-aminophenyl)-1,3,5-triazine is 2:1~1.

5. The volume ratio of 1,3,5-trimethylbenzene, 1,4-dioxane, and acetic acid is 1:1:

2. The mass-to-volume ratio of 2,5-dimethoxy-1,4-dicarboxaldehyde and 1,3,5-trimethylbenzene is 0.594 g: 1 mL. Acetic acid is 36% acetic acid.

2. The method for detecting Al according to claim 1 3+ A method for preparing fluorescence-enhanced imine-type covalent organic framework materials, characterized in that: in, In step S1, the temperature during stirring under water bath heating is 40℃, and the stirring time is 5 minutes. The ultrasound duration is 3 minutes.

3. The method for detecting Al according to claim 1 3+ A method for preparing fluorescence-enhanced imine-type covalent organic framework materials, characterized in that: in, In step S2, the amount of the first mixture added does not exceed 30% of the total volume of the hydrothermal reactor.

4. The method for detecting Al according to claim 1 3+ A method for preparing fluorescence-enhanced imine-type covalent organic framework materials, characterized in that: in, In step S2, the temperature of the reaction in the oven is 120°C and the reaction time is 72 hours.

5. The method for detecting Al according to claim 1 3+ A method for preparing fluorescence-enhanced imine-type covalent organic framework materials, characterized in that: in, In step S2, after soaking in sufficient tetrahydrofuran for at least 24 hours, the mixture is filtered to obtain the second mixture. The second mixture is then extracted with acetone using a Soxhlet extractor for 24 hours and then vacuum dried at 80 °C for 10 hours.

6. A method for detecting Al as described in any one of claims 1 to 5 3+ The covalent organic framework material Dma-TAPT was prepared by a method for preparing fluorescence-enhanced imine-type covalent organic framework materials.

7. A covalent organic framework material, Dma-TAPT, as described in claim 6, for detecting Al 3+ Applications in [the context of the text].

Images