A three-dimensional fluorescent covalent organic framework, its preparation method and application

Abstract

This invention discloses a three-dimensional fluorescent covalent organic framework, its preparation method, and its application. A three-dimensional covalent organic framework with an fjh topological network structure is synthesized by a solvothermal method using a four-site pyrene amino monomer and a three-site aldehyde monomer. This covalent organic framework exhibits excellent fluorescence performance in solution and shows sensitive response and specific detection of nitrofurantoin.

Description

Technical Field

[0001] This invention relates to the field of porous organic crystalline materials technology, specifically to a novel three-dimensional fluorescent covalent organic framework material and its preparation method, as well as its application in fields such as antibiotic detection. Background Technology

[0002] Antibiotics are frequently used in aquaculture as a solution to bacterial infections, but overuse leads to high levels of antibiotic residues in aquatic systems. Currently, antibiotics are considered a serious type of organic pollutant due to their high toxicity, numerous side effects, and difficulty in natural degradation. Because these antibiotics pose a serious threat to human life, there is a need to develop efficient and rapid methods for antibiotic detection and analysis. In recent years, commonly used antibiotic detection methods include liquid chromatography-tandem mass spectrometry (LC-MS / MS), enzyme immunoassay (EI), capillary electrophoresis (CE), and fluorescence detection. Fluorescence methods have received widespread attention in the fields of biological instrumentation and biotherapy, and are widely used in cancer diagnosis and inflammatory diseases. More importantly, fluorescence-based antibiotic analysis methods have several advantages, including ease of operation, low cost, and rapid response.

[0003] Covalent organic frameworks (COFs) are an emerging type of porous material with advantages such as low density, high specific surface area, diverse structures, easily tunable pore structures, and ease of functionalization. They hold great potential in fields such as gas storage / separation, catalysis, sensing, energy storage, and optoelectronics. Two-dimensional or three-dimensional COFs linked by a series of boronic acid ester bonds and imine bonds have achieved single-photon fluorescence by introducing aggregation-induced emission groups or non-planar units and altering the packing mode. Generally, due to strong π-π packing interactions, traditional fluorophores emit only weak fluorescence or no fluorescence at high concentrations or in aggregated states. However, three-dimensional COFs, due to their unique three-dimensional framework, exhibit reduced π-π packing and often possess better fluorescence properties.

[0004] Based on this, the present invention designs a novel three-dimensional covalent organic framework, which is composed of a four-site amino derivative of pyrene with fluorescent emission function and a three-site aldehyde derivative for topology regulation, to obtain a three-dimensional covalent organic framework material with an fjh topological network structure. This framework compound has a sensitive response and specific detection of nitrofurantoin. Summary of the Invention

[0005] The present invention aims to provide a novel three-dimensional fluorescent covalent organic framework, its preparation method and application. The three-dimensional fluorescent covalent organic framework is formed by the reaction of a chromogenic pyrene four-site amine and a three-site aldehyde with a regulated topological structure. The synthesized covalent organic framework has a three-dimensional network, which helps to improve its fluorescence performance and has a sensitive response and specific detection function for nitrofurantoin.

[0006] The technical solution of the present invention is as follows:

[0007] A three-dimensional fluorescent covalent organic framework, obtained by reacting monomers 1a and 1b, has a three-dimensional fjh topological network structure;

[0008] Powder X-ray diffraction measurements revealed three strong peaks at 3.8, 5.1, and 6.8 degrees, which are characteristic peaks of this covalent organic framework.

[0009]

[0010] Monomer 1a is a chromophore with fluorescent emission function, named 1,3,6,8-tetra-(p-aminophenyl)-pyrene, CAS: 2195343-70-3;

[0011] Monomer 1b can regulate the topology of covalent organic frameworks. Name: [1,3,5-trimethyl-2,4,6-tris(4'-aldehydephenyl)]benzene, CAS: 1610471-69-6.

[0012] The three-dimensional fluorescent covalent organic framework described in this invention has a BET specific surface area of ​​1057 m². 2 / g, with an average pore size of 1.44nm; this covalent organic framework is rich in pyrene chromophores in regular three-dimensional channels, which enhances its fluorescence emission. When used for fluorescence detection, its unique three-dimensional structure can greatly increase its contact area with the analyte, thereby improving the sensitivity of fluorescence detection.

[0013] A topological schematic diagram of the three-dimensional fluorescent covalent organic framework described in this invention is shown below. Figure 11 As shown, the square blocks represent the four-site monomer 1a (1,3,6,8-tetra-(p-aminophenyl)-pyrene), and the triangular blocks represent the three-site monomer 1b ([1,3,5-trimethyl-2,4,6-tris(4'-aldehydephenyl)]benzene). This covalent organic framework is a typical three-dimensional fjh topological network structure.

[0014] The preparation method of the three-dimensional fluorescent covalent organic framework of the present invention is as follows:

[0015] Monomers 1a and 1b were added to an organic solvent and ultrasonically dispersed. Then, a catalyst was added, and the mixture was degassed by cyclic freezing. The reaction was carried out at 120°C for 72 hours. After post-treatment, a three-dimensional fluorescent covalent organic framework was obtained.

[0016] The preferred molar ratio of monomer 1a to monomer 1b is 1:1;

[0017] The preferred organic solvent is a mixture of o-dichlorobenzene and n-butanol in a volume ratio of 1:1; the volume molar ratio of the organic solvent to monomer 1a is 1:0.03, mL / mmol;

[0018] The catalyst is acetic acid, preferably fed in the form of a 6 mol / L aqueous acetic acid solution, the volume of which is 10-20% of the volume of the organic solvent;

[0019] Specifically, the operation method of cyclic freezing degassing is as follows: liquid nitrogen is used for freezing, followed by three cycles of freezing and vacuuming to ensure the vacuum level in the reaction vessel;

[0020] Specifically, the post-processing method is as follows: After the reaction is completed, the solid precipitate is filtered and extracted with tetrahydrofuran and acetone by Soxhlet extraction for 12-48 hours (to remove unreacted monomers and small molecule products that have not been fully reacted). After extraction, the product is vacuum dried at 80°C for 12 hours to obtain the final purified product.

[0021] The three-dimensional fluorescent covalent organic framework described in this invention can exhibit fluorescence emission at different wavelengths in different solutions, and has application potential in the fluorescence detection of antibiotics, especially showing a sensitive and specific response to the antibiotic nitrofurantoin.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] (1) Through reasonable structural design, the present invention synthesizes a novel three-dimensional fluorescent covalent organic framework with fjh topology. This covalent organic framework has high crystallinity, large specific surface area and good thermal stability.

[0024] (2) The three-dimensional fluorescent covalent organic framework described in this invention has a simple synthesis procedure, requires inexpensive monomers, and has good industrialization potential.

[0025] (3) The three-dimensional fluorescent covalent organic framework described in this invention has excellent fluorescence performance. In the experiment, nitrofurantoin has a sensitive fluorescence detection effect and has great application potential. Attached Figure Description

[0026] Figure 1 Powder X-ray spectra and simulated spectra of a three-dimensional fluorescent covalent organic framework.

[0027] Figure 2 The image shows the infrared spectrum of a three-dimensional fluorescent covalent organic framework.

[0028] Figure 3 The nitrogen isotherm adsorption-desorption curves and corresponding pore size distribution diagrams are shown for the three-dimensional fluorescent covalent organic framework.

[0029] Figure 4 Thermogravimetric analysis spectrum of a three-dimensional fluorescent covalent organic framework.

[0030] Figure 5 The fluorescence excitation spectra of the three-dimensional fluorescent covalent organic framework in different solvents are shown.

[0031] Figure 6 This is a comparison of the quantum yields of three-dimensional fluorescent covalent organic frameworks in different solvents.

[0032] Figure 7 The CIE spectra of a three-dimensional fluorescent covalent organic framework in different solvents.

[0033] Figure 8 The fluorescence change curve of a three-dimensional fluorescent covalent organic framework dispersed in dimethyl sulfoxide solution and titrated with nitrofurantoin.

[0034] Figure 9 Stern-Wolmer diagram of a three-dimensional fluorescent covalent organic framework.

[0035] Figure 10 A graph showing the selective detection of nitrofurantoin in the presence of other antibiotics using COF.

[0036] Figure 11 This is a topological schematic diagram of the three-dimensional fluorescent covalent organic framework of the present invention.

[0037] Figure 12 This is a schematic diagram of the structure of the three-dimensional fluorescent covalent organic framework of the present invention. Detailed Implementation

[0038] The present invention is further described below through specific embodiments. The following examples are helpful for those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0039] Example 1

[0040] (1) Synthesis method of three-dimensional fluorescent covalent organic framework

[0041] 17 mg (0.03 mmol) of monomer 1a (1,3,6,8-tetra-(p-aminophenyl)-pyrene) and 17 mg (0.03 mmol) of monomer 1b ([1,3,5-trimethyl-2,4,6-tris(4'-aldehydephenyl)]benzene) were added to a Schlenk tube containing o-dichlorobenzene (0.5 mL) and n-butanol (0.5 mL). The solution was sonicated for 5 minutes to ensure uniform dispersion. 0.1 mL of 6M aqueous acetic acid was added to the Schlenk tube as a catalyst. The Schlenk tube was rapidly frozen at 77 K using a liquid nitrogen bath and degassed three times using a freeze-thaw degassing method to maintain vacuum. After returning to room temperature, the Schlenk tube was placed in a 120 °C oven for 3 days. After the reaction was completed, the yellow powder product was separated by filtration, and then the sample was further activated by Soxhlet extraction with tetrahydrofuran and acetone for 12 h. After Soxhlet extraction, the sample was transferred to a vacuum oven and vacuum dried at 80 °C for 12 h to obtain yellow powder COFs material.

[0042] (2) Product characterization

[0043] See Figure 1 Powder X-ray diffraction measurements showed that the obtained COFs exhibited diffraction peaks at 3.8, 5.1, and 6.8 degrees, confirming the successful synthesis of the COFs material and its high crystallinity. Structural simulation using Materials Studio software resolved the crystal structure of the COFs. The simulated PXRD pattern generated by the simulated structure matched the experimental PXRD pattern well, proving the correctness of the structure.

[0044] See Figure 2 Fourier transform infrared (FT-IR) spectroscopy was performed. By comparing the infrared spectra of the relevant monomers required for synthesis with the corresponding COFs materials, the products showed a peak intensity at 1625 cm⁻¹. -1 The characteristic stretching vibrations of C=N bonds were generated at the point, and the characteristic peaks of amino and aldehyde groups were greatly weakened, proving the successful synthesis of COFs materials.

[0045] See Figure 3 Nitrogen isothermal adsorption-desorption curves and corresponding pore size distribution diagrams. The calculated BET specific surface area of ​​the COFs material is 1057 m². 2 The large specific surface area indicates its high application potential in various fields. The pore size distribution of COFs material was obtained by using empirical formulas based on nitrogen isothermal adsorption-desorption data. The average pore size is 1.4 nm, which also corresponds to the simulation data of the simulated fjh topology.

[0046] See Figure 4Thermogravimetric analysis showed that the obtained COFs material remained basically stable at 500℃, indicating that the COFs material has good thermal stability.

[0047] See Figure 5 The fluorescence excitation spectra of COFs materials in different solvents show that they have strong fluorescence properties in a variety of organic solvents, with the longest emission wavelength at 500 nm in dimethyl sulfoxide.

[0048] See Figure 6 The comparison of quantum yield of COFs materials in different solvents shows that when acetonitrile is used as the solvent, COFs materials have a high fluorescence emission yield of 61.2%.

[0049] See Figure 7 The CIE spectra of three-dimensional fluorescent covalent organic frameworks in different solvents show that COFs materials have different emission wavelengths in different solvents, indicating that they have good application prospects in fluorescence detection.

[0050] (3) Antibiotic detection experiment

[0051] See Figure 8 At 298 K, 2 mg of a three-dimensional fluorescent covalent organic framework was ultrasonically dispersed in 3 mL of dimethyl sulfoxide solution to form a suspension. Then, 0.01 mmol of nitrofurantoin was added to the suspension, and its fluorescence emission spectrum was measured at 298 K and 365 nm excitation wavelength using a fluorescence spectrometer (F-4600). The fluorescence spectrum showed that the framework material exhibited an aggregation quenching effect when it encountered nitrofurantoin.

[0052] See Figure 9 ,pass Figure 8 Data from the fluorescence quenching experiment were used to construct a Stern-Wolmer plot. The well-fitting straight line indicates that nitrofurantoin can linearly quench the fluorescence emission of COFs materials, with a relatively high K value (K = 8.5 * 10⁻⁶). 4 This directly demonstrates its highly sensitive response to nitrofurantoin.

[0053] See Figure 10 The selective detection of nitrofurantoin by COFs materials under interference from other antibiotics was studied. The prepared COFs materials showed sensitive and specific responses to nitrofurantoin under interference from antibiotics such as amoxicillin, ibuprofen, sulfadiazine, carbamazepine, chloramphenicol, and cyproterone, indicating their excellent fluorescence detection performance.

[0054] The above-described embodiments merely illustrate preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of the present invention. The technical features of the embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described, but as long as these combinations do not contradict each other, they should be considered within the scope of this specification. For those skilled in the art, several modifications and variations can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. Application of a three-dimensional fluorescent covalent organic framework in the fluorescent detection of the antibiotic nitrofurantoin. The three-dimensional fluorescent covalent organic framework is obtained by reacting monomer 1a and monomer 1b, and has a three-dimensional fjh topological network structure. 1a 1b.

2. Use according to claim 1, wherein The three-dimensional fluorescent covalent organic framework has three strong peaks at 3.8, 5.1 and 6.8 degrees by powder X-ray diffraction measurement, which are characteristic peaks of the covalent organic framework.

3. The use according to claim 1, wherein The preparation method of the three-dimensional fluorescent covalent organic framework is as follows: Monomer 1a and monomer 1b are added to an organic solvent, ultrasonically dispersed uniformly, then a catalyst is added, and the mixture is subjected to cyclic freeze degassing, reacted at 120 DEG C for 72 h, and then subjected to post-treatment to obtain the three-dimensional fluorescent covalent organic framework. The catalyst is acetic acid.

4. Use according to claim 3, wherein the compound is ###0002### The molar ratio of monomer 1a to monomer 1b is 1:

1.

5. The use according to claim 3, wherein the compound is ###0002### The organic solvent is a mixed solvent of o-dichlorobenzene and n-butanol in a volume ratio of 1:

1.

6. The use according to claim 3, wherein the compound is ###0002### The catalyst is fed in the form of a 6 mol / L acetic acid aqueous solution, and the volume of the 6 mol / L acetic acid aqueous solution is 10-20% of the volume of the organic solvent.

7. The use according to claim 3, wherein the compound is ###00003### or a pharmaceutically acceptable salt thereof. The post-treatment method is as follows: after the reaction is completed, the solid precipitate product is filtered, and is subjected to Soxhlet extraction with tetrahydrofuran and acetone respectively for 12-48 h, and then is vacuum dried at 80 DEG C for 12 h to obtain the final purified product.

Images