A ratio type rare earth functionalized covalent organic framework fluorescent probe, a preparation method and application thereof

Abstract

The present application relates to a kind of ratio type rare earth functional covalent organic framework fluorescent probe and preparation method and application, the fluorescent probe includes covalent organic framework and rare earth ion;The covalent organic framework includes first connector and second connector;The first connector is 3,3"-dihydroxy-[1,1':4',1"-terphenyl]-4,4"-dialdehyde;The rare earth ion is scandium ion.The fluorescent probe prepared in the application can realize the detection of enrofloxacin, norfloxacin and perfloxacin in the environment, compared with the resistance of other fluorescent probes to the change of external environment factor is higher, and the recognition result is more accurate and reliable;And its preparation method is simple, product yield is high, and it is suitable for mass production application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental detection, and particularly relates to a ratio type rare earth functionalized covalent organic framework fluorescent probe, a preparation method and application thereof. BACKGROUND

[0002] Since the discovery of antibiotics, they have played a crucial role in human production and life. In the prevention and treatment of diseases, as well as in livestock and aquaculture, the use of antibiotics has greatly reduced the incidence of disease and mortality. However, the antibiotics used in the treatment process are not completely absorbed and utilized by humans and animals, and the overuse of antibiotics has led to the frequent occurrence of these substances in the environment and in the body, thereby triggering a series of environmental and health problems. For example, the emergence of antibiotic resistance genes reduces the effectiveness of antibiotic treatment, and the residues of antibiotics in water and soil change the biochemical properties, thereby affecting the structure of biological populations.

[0003] The commonly used types of antibiotics currently include quinolones, macrolides, sulfonamides and tetracyclines, among which quinolones are particularly concerned due to their wide variety and extensive use. Enrofloxacin, norfloxacin and perfloxacin, as the third generation of quinolone antibacterial drugs, are widely used in the prevention and treatment of bacterial diseases in livestock and aquatic animals. However, due to their low metabolic and absorption rate in the animal body, antibiotics are prone to remain in the environment, causing serious environmental pollution and ecological damage. Therefore, in the face of this potential ecological and health risk, it is urgent to develop effective pollution control measures, and early detection of antibiotics provides the necessary basis and direction for related management. In this context, the efficient recognition of enrofloxacin, norfloxacin and perfloxacin is particularly important, especially the use of sensitive, convenient, economical and suitable for on-site detection technology has important practical significance.

[0004] Currently, a variety of detection techniques have been widely used in antibiotic detection, such as high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS / MS), capillary electrophoresis, micellar liquid chromatography and surface acoustic wave sensing, etc. However, these methods usually require complex sample pretreatment and rely on expensive instruments, so the development of low-cost, simple-to-operate on-site monitoring technology has become the current research focus. Among the many detection techniques, the fluorescent probe method has gradually stood out from the crowd due to its advantages of portability, sensitivity and strong specificity, and has become an ideal choice for antibiotic detection.

[0005] CN112816448A discloses a fluorescence detection method for rapid detection of tetracycline in food, which is prepared by preparing carbon quantum dots and mercaptoacetic acid modified cadmium telluride quantum dots (CQDs / TGA-CdTe QDs) solution as a ratio fluorescent probe. The invention uses monohydrate citric acid as a carbon source and reducing glutathione as a nitrogen / sulfur source. First, CQDs and red luminescent TGA-CdTe QDs are synthesized by hydrothermal method, and then CQDs and TGA-CdTe QDs are mixed together in a certain proportion to prepare CQDs / TGA-CdTe QDs ratio fluorescent probe. The probe can greatly exclude the interference of external environment by its own dual fluorescence self-reference effect, and realize more accurate quantitative detection, but the use of heavy metal cadmium will undoubtedly pollute the environment and even affect the health of the user if not used properly.

[0006] CN118956390A discloses a fluorescence probe for detecting gatifloxacin and its application in food. A novel biological matrix derived carbon quantum dot is prepared using bear gall powder as a precursor, and a highly selective fluorescence sensing platform is constructed, which is successfully used for detecting gatifloxacin in milk and honey. The color of the system changes from blue fluorescence to green fluorescence under ultraviolet light. By establishing the linearity between the fluorescence signal intensity and the concentration of gatifloxacin, sensitive detection of gatifloxacin is realized, and the detection limit can be as low as 3 μg / L. However, the raw materials for preparation are limited in source and expensive, and more importantly, the color change is not obvious, which will cause large errors in naked eye identification of the solution.

[0007] CN118063787A discloses a metal organic framework fluorescent probe for specifically detecting tetracycline antibiotics and a preparation method thereof, which can realize qualitative and quantitative detection of tetracycline. The material has the advantages of rapidity, simplicity, good selectivity, high sensitivity, etc. Three different antibiotics can be recognized and detected, and the preparation method of the material is simple, has high purity and good activity. However, the material for recognition is single quenching type detection, which is easily disturbed by external substances and causes measurement errors.

[0008] Therefore, it is very meaningful to develop more fluorescence probe strategies for detecting antibiotics, especially for detecting quinolone antibiotics. SUMMARY

[0009] To solve the above technical problems, the present application provides a ratio type rare earth functionalized covalent organic framework fluorescent probe, a preparation method and application. By coordination of scandium ions with covalent organic frameworks, the influence of other interfering substances is weakened while the rare earth ions are protected, and enrofloxacin, norfloxacin and pefloxacin in water can be detected more sensitively and portably.

[0010] To achieve this purpose, the present application adopts the following technical solutions:

[0011] In a first aspect, the present application provides a ratio-type rare earth functionalized covalent organic framework fluorescent probe, the fluorescent probe comprising a covalent organic framework and a rare earth ion; the covalent organic framework comprising a first linker and a second linker;

[0012] The first linker is 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde; and the rare earth ion is scandium ion.

[0013] The covalent organic framework in the present application has a highly adjustable pore structure and surface property, good stability, high specific surface area and accessible porosity, multifunctionality and adjustability, and strong fluorescence emission, which can play a fluorescence reference role in the detection process; at the same time, the rare earth ion such as scandium ion can play a role of sensitized fluorescence enhancement on organic molecules, therefore, the present application provides protection for the rare earth ion through coordination of the covalent organic framework and scandium ion, and also plays a certain pore barrier role, which weakens the influence of other interfering substances, so that the fluorescent probe has higher sensitivity and selectivity in fluorescence sensing.

[0014] As a preferred technical solution of the present application, the second linker comprises any one of 1,3,5-tris(4-aminophenyl)benzene, 1,3,5-tris(4-formylphenyl)benzene, 1,3,5-trihydroxybenzene or 1,3,5-triaminobenzene.

[0015] In a second aspect, the present application provides a preparation method of the fluorescent probe according to the first aspect, the preparation method comprising:

[0016] (1) mixing 1,4-benzenediboronic acid and 4-bromo-2-hydroxybenzaldehyde, then adding a lye and a first catalyst to react, adjusting the pH after the reaction, and then solid-liquid separation to obtain a first linker;

[0017] (2) mixing the second linker with the first linker, then adding a second catalyst to react, and then solid-liquid separation to obtain a covalent organic framework precursor;

[0018] (3) mixing the covalent organic framework precursor with a scandium salt to perform a coordination reaction, then solid-liquid separation after the reaction to obtain the ratio-type rare earth functionalized covalent organic framework fluorescent probe.

[0019] The preparation technical route of the fluorescent probe in the present application is as follows: 1,4-benzenediboronic acid and 4-bromo-2-hydroxybenzaldehyde are subjected to Suzuki coupling reaction to obtain a first linker 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde. Then, 1,3,5-tris(4-aminophenyl)benzene (a second linker) and 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde are used as precursors to realize condensation of aldehyde groups and amino groups under hydrothermal conditions to form a covalent organic framework (COF) material COF-3 with a crystal form, and then trivalent scandium ions are anchored on the COF structure to obtain the probe COF-3-Sc.

[0020] As a preferred technical solution of the present application, the 1,4-benzenediboronic acid and the 4-bromo-2-hydroxybenzaldehyde in step (1) are mixed in an organic solvent.

[0021] Preferably, the organic solvent includes any one or a combination of at least two of methanol, ethanol, toluene, tetrahydrofuran or anhydrous acetonitrile, and typical but non-limiting examples include methanol and ethanol, toluene and tetrahydrofuran, methanol and anhydrous acetonitrile, etc.

[0022] Preferably, the lye includes potassium carbonate and / or potassium phosphate.

[0023] Preferably, the first catalyst includes tetrakis(triphenylphosphine)palladium or palladium acetate.

[0024] As a preferred technical solution of the present application, the reaction in step (1) is carried out under a protective atmosphere.

[0025] Preferably, the protective atmosphere includes nitrogen and / or argon.

[0026] Preferably, the temperature of the reaction is 50-80℃, such as 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, etc., but is not limited to the listed values, and other values not listed in the above value range are also applicable, and further preferably 60-80℃.

[0027] Preferably, the time of the reaction is 12-24h, such as 12h, 14h, 16h, 18h, 20h, 22h, 24h, etc., but is not limited to the listed values, and other values not listed in the above value range are also applicable, and further preferably 20h-24h.

[0028] Preferably, the adjustment of pH is specifically adjusting the pH of the solution to be acidic to generate a precipitate.

[0029] Preferably, after the solid-liquid separation, washing and drying are performed to obtain the first linker.

[0030] Preferably, the washing is performed using methanol and water.

[0031] Preferably, the second linker in step (2) is mixed with the first linker in an organic solvent.

[0032] Preferably, the organic solvent comprises any one or a combination of at least two of 1,4-dioxane, dimethyl sulfoxide or dimethyl formamide, such as 1,4-dioxane and dimethyl sulfoxide, 1,4-dioxane and dimethyl formamide, dimethyl sulfoxide and dimethyl formamide.

[0033] Preferably, the second catalyst comprises acetic acid.

[0034] Preferably, the reaction in step (2) is performed under a protective atmosphere.

[0035] Preferably, the protective atmosphere comprises nitrogen and / or argon.

[0036] Preferably, the reaction is performed at a temperature of 60-120℃, such as 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 110℃, 120℃, etc., but not limited to the listed values, and other values not listed within the above range are also applicable, and further preferably 90-120℃.

[0037] Preferably, the reaction is performed for a time of 3-5d, such as 3d, 3.5d, 4d, 4.5d, 5d, etc., but not limited to the listed values, and other values not listed within the above range are also applicable, and further preferably 3d.

[0038] Preferably, the covalent organic framework precursor is obtained after washing and drying after the solid-liquid separation.

[0039] Preferably, the washing is performed at least three times using tetrahydrofuran and ethanol.

[0040] Preferably, the mass ratio of the covalent organic framework precursor to the scandium salt in step (3) is 1:(0.5-2), such as 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, etc., but not limited to the listed values, and other values not listed within the above range are also applicable, and further preferably 1:(0.5-1).

[0041] Preferably, the scandium salt comprises any one of scandium chloride hexahydrate, scandium nitrate, scandium sulfate, scandium triflate or scandium oxide or a combination of at least two of them, such as scandium chloride hexahydrate and scandium nitrate, scandium sulfate and scandium triflate, scandium sulfate and scandium oxide, scandium chloride hexahydrate and scandium oxide, etc.

[0042] As a preferred technical solution of the present application, the covalent organic framework precursor in step (3) is mixed with the scandium salt in an organic solvent.

[0043] Preferably, the organic solvent is anhydrous acetonitrile.

[0044] Preferably, the temperature of the coordination reaction is 60-80℃, such as 60℃, 65℃, 70℃, 75℃, 80℃, etc., but not limited to the listed values, and other values not listed in the above value range are also applicable, and further preferably 60℃.

[0045] The time of the coordination reaction is 6-24h, such as 6h, 9h, 12h, 15h, 18h, 21h, 24h, etc., but not limited to the listed values, and other values not listed in the above value range are also applicable, and further preferably 18-24h.

[0046] Preferably, after the solid-liquid separation, washing and drying are performed to obtain the ratio type rare earth functionalized covalent organic framework fluorescent probe.

[0047] Preferably, the washing is performed by flushing with anhydrous ethanol.

[0048] In a third aspect, the present application provides a use of the fluorescent probe according to the first aspect for detecting quinolone antibiotics.

[0049] Preferably, the quinolone antibiotics comprise any one of enrofloxacin, norfloxacin or perfloxacin or a combination of at least two of them, such as enrofloxacin and norfloxacin, enrofloxacin and perfloxacin, norfloxacin and perfloxacin.

[0050] Compared with the prior art, the present application has at least the following beneficial effects:

[0051] (1) The present application prepares the linker 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde with aggregation-induced emission effect through a one-step simple Suzuki coupling reaction, and the preparation process is simple and the product yield is high.

[0052] (2) The present application provides protection for rare earth ions through the coordination of covalent organic framework and scandium ions, and also plays a certain pore blocking role, reducing the influence of other interfering substances.

[0053] (3) The fluorescent probe of the present application can specifically recognize quinolone antibiotics enoxacin, norfloxacin and perfloxacin, and has higher resistance to changes in external environmental factors compared with common "turn-off" or "turn-on" fluorescent probes, and the recognition result is more accurate and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 is a synthesis diagram of the first linker 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde.

[0055] Figure 2 is the nuclear magnetic hydrogen spectrum (a) and carbon spectrum (b) of the first linker 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde.

[0056] Figure 3 is the aggregation-induced emission light condition of the first linker 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde.

[0057] Figure 4 is a synthesis diagram of the covalent organic framework precursor COF-3.

[0058] Figure 5 is a Fourier infrared spectrum comparison diagram of the ligand and COF-3 before and after the synthesis of the covalent organic framework material.

[0059] Figure 6 is a powder XRD spectrum of the covalent organic framework precursor COF-3.

[0060] Figure 7 is a scanning electron microscope SEM (a) and transmission electron microscope TEM image (b) of the covalent organic framework precursor COF-3.

[0061] Figure 8 is a fluorescence emission spectrum diagram of COF-3 under 365nm excitation light.

[0062] Figure 9 is a construction diagram of the fluorescent probe COF-3-Sc.

[0063] Figure 10 is a transmission electron microscope TEM picture and element distribution condition in EDS test diagram of the fluorescent probe COF-3-Sc.

[0064] Figure 11 is an XPS comparison diagram of O1s in the covalent organic framework COF-3 and the fluorescent probe COF-3-Sc.

[0065] Figure 12The fluorescence spectrum changes of the fluorescent probe COF-3-Sc under different concentrations of enrofloxacin (a), norfloxacin (b) and pefloxacin (c). DETAILED DESCRIPTION

[0066] The technical solutions of the present application are further illustrated below in combination with the drawings and through specific embodiments. However, the following examples are only simple examples of the present application and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims.

[0067] Embodiment 1

[0068] The embodiment provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, and the preparation method comprises the following steps:

[0069] (1) 1,4-benzenediol (414.4 mg, 2.5 mmol) and 4-bromo-2-hydroxybenzaldehyde (1.005 g, 5 mmol) are dispersed in a 50 ml methanol solution, potassium carbonate solution (2M, 15 mL) and tetrakis(triphenylphosphine)palladium (56 mg) are added, and the reaction is carried out under nitrogen protection at 50 DEG C for 24 h; after the reaction, the pH is adjusted to be acidic to generate a precipitate, and after solid-liquid separation, the precipitate is washed with methanol and water, and after drying, a first linker 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde is obtained;

[0070] (2) 1,3,5-tris(4-aminophenyl)benzene (17.6 mg, 0.05 mmol) and 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde (23.9 mg, 0.075 mmol) are dissolved in a mixed solution of 1,4-dioxane and dimethyl sulfoxide (10 mL, 4:1), 0.2 mL of acetic acid is added, and the reaction is carried out under nitrogen protection at 60 DEG C for 3 d; after solid-liquid separation, the precipitate is washed with tetrahydrofuran and ethanol for at least three times, and after drying, a covalent organic framework precursor COF-3 is obtained;

[0071] (3) COF-3 (50 mg) is uniformly dispersed in 20 mL of an acetonitrile solution by ultrasonic dispersion, scandium chloride hexahydrate (25 mg) is added, and the reaction is carried out under 60 DEG C condensation reflux for 24 h; after the reaction, solid-liquid separation is carried out, the precipitate is washed with ethanol, and after drying, a fluorescent probe COF-3-Sc is obtained.

[0072] Embodiment 2

[0073] The embodiment provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, and the preparation method comprises the following steps:

[0074] (1) 1,4-benzenediol (414.4 mg, 2.5 mmol) and 4-bromo-2-hydroxybenzaldehyde (1.005 g, 5 mmol) were dispersed in 50 ml of methanol solution, potassium carbonate solution (2M, 15 mL) and tetrakis(triphenylphosphine)palladium (56 mg) were added, and the reaction was carried out under nitrogen protection at 60°C for 20h. After the reaction, the pH was adjusted to be acidic to produce a precipitate, and the solid-liquid separation was carried out, and then methanol and water were used for washing, and after drying, the first linker 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dial was obtained;

[0075] (2) 1,3,5-tris(4-aminophenyl)benzene (17.6 mg, 0.05 mmol) and 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dial (23.9 mg, 0.075 mmol) were dissolved in a mixed solution of 1,4-dioxane and dimethyl sulfoxide (10 mL, 4:1), 0.2 mL of acetic acid was added, and the reaction was carried out under nitrogen protection at 90°C for 3d. After the reaction, the solid-liquid separation was carried out, and then tetrahydrofuran and ethanol were used for washing at least three times, and after drying, the covalent organic framework precursor COF-3 was obtained;

[0076] (3) COF-3 (50 mg) was uniformly dispersed in 20 mL of acetonitrile solution by ultrasonic, and scandium chloride hexahydrate (50 mg) was added, and the reaction was carried out under 60°C condensation reflux for 18h. After the reaction, the solid-liquid separation was carried out, and then ethanol was used for washing, and after drying, the fluorescent probe COF-3-Sc was obtained.

[0077] Example 3

[0078] The embodiment provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, and the preparation method comprises the following steps:

[0079] (1) 1,4-benzenediol (414.4 mg, 2.5 mmol) and 4-bromo-2-hydroxybenzaldehyde (1.005 g, 5 mmol) were dispersed in 50 ml of methanol solution, potassium carbonate solution (2M, 15 mL) and tetrakis(triphenylphosphine)palladium (56 mg) were added, and the reaction was carried out under nitrogen protection at 70°C for 16h. After the reaction, the pH was adjusted to be acidic to produce a precipitate, and the solid-liquid separation was carried out, and then methanol and water were used for washing, and after drying, the first linker 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dial was obtained;

[0080] (2) 1,3,5-tris(4-aminophenyl)benzene (17.6 mg, 0.05 mmol) and 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dial (23.9 mg, 0.075 mmol) were dissolved in a mixed solution of 1,4-dioxane and dimethyl sulfoxide (10 mL, 4:1), 0.2 mL acetic acid was added, and the reaction was carried out at 120 °C for 3 d under nitrogen protection. After solid-liquid separation, the product was washed with tetrahydrofuran and ethanol at least three times, and dried to obtain the covalent organic framework precursor COF-3;

[0081] (3) COF-3 (50 mg) was uniformly dispersed in 20 mL acetonitrile solution by ultrasonic, and scandium chloride hexahydrate (100 mg) was added. The reaction was carried out at 70 °C for 12 h under condensation reflux. After the reaction, solid-liquid separation was carried out, and the product was washed with ethanol and dried to obtain the fluorescent probe COF-3-Sc.

[0082] Example 4

[0083] The embodiment provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, and the preparation method comprises the following steps:

[0084] (1) 1,4-benzenediboronic acid (414.4 mg, 2.5 mmol) and 4-bromo-2-hydroxybenzaldehyde (1.005 g, 5 mmol) were dispersed in 50 ml of methanol solution, potassium carbonate solution (2M, 15 mL) and tetrakis(triphenylphosphine)palladium (56 mg) were added, and the reaction was carried out at 80 °C for 12 h under nitrogen protection. After the reaction, the pH was adjusted to be acidic to produce a precipitate, and the precipitate was washed with methanol and water after solid-liquid separation, and dried to obtain the first linker 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dial;

[0085] (2) 1,3,5-tris(4-aminophenyl)benzene (17.6 mg, 0.05 mmol) and 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dial (23.9 mg, 0.075 mmol) were dissolved in a mixed solution of 1,4-dioxane and dimethyl sulfoxide (10 mL, 4:1), 0.2 mL acetic acid was added, and the reaction was carried out at 150 °C for 3 d under nitrogen protection. After solid-liquid separation, the product was washed with tetrahydrofuran and ethanol at least three times, and dried to obtain the covalent organic framework precursor COF-3;

[0086] (3) COF-3 (50 mg) was uniformly dispersed in 20 mL acetonitrile solution by ultrasonic, and scandium chloride hexahydrate (150 mg) was added. The reaction was carried out at 80 °C for 8 h under condensation reflux. After the reaction, solid-liquid separation was carried out, and the product was washed with ethanol and dried to obtain the fluorescent probe COF-3-Sc.

[0087] Example 5

[0088] The embodiment provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, which is identical to the embodiment 1 except that the reaction temperature of the step (1) is 80 DEG C.

[0089] Example 6

[0090] The embodiment provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, which is identical to the embodiment 1 except that the reaction time of the step (2) is 4d.

[0091] Example 7

[0092] The embodiment provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, which is identical to the embodiment 2 except that the reaction time of the step (2) is 1d.

[0093] Example 8

[0094] The embodiment provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, which is identical to the embodiment 2 except that the reaction temperature of the step (2) is 30 DEG C.

[0095] Example 9

[0096] The embodiment provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, which is identical to the embodiment 2 except that the addition amount of the scandium chloride hexahydrate of the step (3) is 10mg.

[0097] Comparative Example 1

[0098] The comparative example provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, which is identical to the embodiment 2 except that the scandium chloride hexahydrate is added in the step (3).

[0099] Comparative Example 2

[0100] The comparative example provides a preparation method of a ratio type rare earth functionalized covalent organic framework fluorescent probe, which is identical to the embodiment 2 except that the step (1) is omitted, and the covalent organic framework precursor is synthesized by the reaction of 1,3,5-tris (4-aminophenyl) benzene and 2,6-pyridine dicarboxaldehyde in the step (2).

[0101] Performance detection

[0102] The fluorescent probe COF-3-Sc prepared in Examples 1-9 and Comparative Examples 1 and 2 were used to detect and identify enrofloxacin, norfloxacin, and pefloxacin, respectively. The specific test methods are as follows:

[0103] Enrofloxacin detection: 5 mg of the fluorescent probe COF-3-Sc prepared in Examples 1-9 and Comparative Examples 1 and 2 were weighed and dispersed in 1 mL of dimethyl sulfoxide to prepare a 5 mg / mL fluorescent probe stock solution. 40 µL of the fluorescent probe stock solution was placed in a cuvette, followed by the addition of 1.95 mL of deionized water. Then, 10 µL of enrofloxacin solutions of different concentrations were added dropwise to achieve enrofloxacin concentrations of 5 µM, 10 µM, 15 µM, 20 µM, and 25 µM. After reacting for 10 min, spectral analysis was performed under 330 nm excitation light. The ratio of different materials at 430 nm and 556 nm was measured, and the slope K value was obtained by fitting the curve.

[0104] The detection and identification test methods for norfloxacin and pefloxacin are as described above, and the test results are shown in Table 1.

[0105]

[0106] The slope K reflects the fluorescence change of the probe in response to antibiotics; a larger K value indicates greater sensitivity to antibiotics in the system. During synthesis, reaction temperature and time directly affect the crystal structure of the COFs material; an ordered spatial structure facilitates successful sensing. Secondly, Sc... 3+ The content of Sc directly affects the sensitization luminescence to antibiotics, therefore Sc 3+ The amount added should be sufficient to coordinate with the binding sites in COFs.

[0107] As can be seen from Examples 1-6, under the condition of ensuring the reaction proceeds fully, increasing the reaction time, temperature, and Sc... 3+ The amount of [something] will have a significant impact on detection efficiency; and comparing Example 2 and Examples 7-9, it can be seen that the reaction time, temperature, and [something] [are all factors that affect the detection efficiency]. 3+ Insufficient addition will affect the sensing performance of the material.

[0108] By comparing Example 2 with Comparative Example 1, it can be seen that using Eu 3+ Fluorescent probes prepared using coordination covalent organic frameworks exhibit poor sensing performance for antibiotics, primarily because Eu... 3+The sensor cannot enhance the luminescence of the three antibiotics at 430 nm; instead, it uses the antenna effect to divert the energy absorbed by norfloxacin to sensitize its own luminescence at 612 nm. For enrofloxacin and pefloxacin, it can only rely on their weak fluorescence for contrast, resulting in reduced sensing performance. For norfloxacin, the luminescence at 612 nm is very close to the luminescence wavelength of the covalent organic framework, making effective ratiometric detection impossible.

[0109] By comparing Example 2 and Comparative Example 2, it can be seen that although the covalent organic framework synthesized in Comparative Example 2 can also interact with Sc... 3+ Coordination was performed, but the prepared fluorescent probes showed poor sensing performance for antibiotics, mainly because the covalent organic framework precursors synthesized by this method cannot emit light themselves and can only rely on Sc. 3+ The enhanced single fluorescence emission of antibiotics at 430 nm cannot achieve the effect of ratiometric detection.

[0110] Furthermore, according to Example 2, while ensuring good detection results, the conditions for preparing the materials are also milder, avoiding waste of time, energy, and materials. Therefore, considering both preparation efficiency and detection capability, the materials obtained in Example 2 were used for corresponding tests.

[0111] The materials obtained in Example 2 were characterized accordingly, and the results are illustrated in the figures.

[0112] In the early stages of material preparation, a first linker with aggregation-induced emission effect, 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde, was easily prepared based on the Suzuki coupling reaction. Figure 1 Subsequently, its structure was determined by testing with 1H and 1C NMR spectra. Figure 2 Tests revealed that the first linker is soluble in dimethyl sulfoxide but poorly soluble in water. When the first linker dissolved in dimethyl sulfoxide, almost no fluorescence was produced. However, when different proportions of water were added to the system, the first linker gradually precipitated out, and the fluorescence of the system continuously increased. Figure 3 Subsequently, we successfully constructed the covalent organic framework precursor COF-3 using 1,3,5-tris(4-aminophenyl)benzene and 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde according to the procedure in Example 2. Figure 4 ).

[0113] Subsequently, the covalent organic framework precursor COF-3 underwent corresponding structural characterization and testing. For example... Figure 5 As shown, FITR results indicate that after the first step of the Schiff base reaction, the amino vibration peak of 1,3,5-tris(4-aminophenyl)benzene (3420 cm⁻¹) is present. -1 and 3345cm-1 ) and 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde (1668 cm -1 ) could not be observed, while the formation of C=N bond (1618 cm -1 ) could be clearly observed from the test of the product, indicating that the amino and aldehyde groups have successfully combined to form the covalent organic framework precursor COF-3.

[0114] As shown in Figure 6 , the PXRD test determines that the material is crystalline, and the test results show that the material has a strong crystal diffraction peak at 2ɵ=2.0°, further confirming the synthesis of the covalent organic framework precursor COF-3. Figure 7 The scanning electron microscope and transmission electron microscope images of COF-3 show that COF-3 is a uniformly dispersed spherical structure. Importantly, COF-3 material produces strong fluorescence emission at 556 nm under the excitation of ultraviolet light, providing a basis for the construction of a ratiometric fluorescent probe Figure 8 ).

[0115] Finally, the scandium ion is fixed on COF-3 by electrostatic adsorption and van der Waals force Figure 9 . The energy spectrum analysis test of the transmission electron microscope shows that Sc 3+ is uniformly dispersed in COF-3, and the XPS test also verifies the formation of Sc-O bond, indicating that COF-3-Sc is successfully prepared Figure 10 and Figure 11 ).

[0116] When enoxacin, norfloxacin and perfloxacin are coordinated with trivalent scandium, the rigid structure of the molecule will be further increased, and the fluorescence will also be further enhanced. After the combination of scandium ion and COF-3, COF-3 can not only provide support and protection for Sc 3+ , but also can play a role as a reference fluorescence. The test results show that COF-3-Sc is a ratiometric detection for the three kinds of antibiotics, and with the increase of the concentration of the antibiotics, the fluorescence intensity around 430 nm is further enhanced; while the fluorescence of COF-3-Sc material at 556 nm will also be slightly enhanced due to the fluorescence resonance energy transfer (FRET) effect, but due to the dominant role of the inner filter effect (IFE), the color of the whole system changes from orange to purple Figure 12 ).

[0117] In summary, the application provides a ratio type rare earth functional covalent organic framework fluorescent probe, a preparation method and an application, a first linker is synthesized through a one-step Suzuki coupling reaction, the method is simple, and the product yield is high; and through coordination of the covalent organic framework and scandium ions, the rare earth ions are protected, meanwhile, a certain channel blocking effect is achieved, the influence of other interference substances is weakened, and more sensitive and portable detection of enrofloxacin, norfloxacin and perfloxacin in water is realized.

[0118] The applicant declares that the above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto, and those skilled in the art should understand that any change or replacement within the technical scope disclosed by the application, which can be easily thought of by any person skilled in the art, falls within the protection scope and disclosure scope of the application.

Claims

1. A ratiometric rare earth functionalized covalent organic framework fluorescent probe characterized in that, The fluorescent probe comprises a covalent organic framework and a rare earth ion; the covalent organic framework comprises a first linker and a second linker; The first linker is 3,3''-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-dialdehyde; the rare earth ion is scandium ion; and the second linker comprises 1,3,5-tris(4-aminophenyl)benzene.

2. A method for preparing the fluorescent probe according to claim 1, characterized by, The preparation method comprises: (1) mixing 1,4-benzenediboronic acid and 4-bromo-2-hydroxybenzaldehyde, then adding a lye and a first catalyst to react, adjusting pH after the reaction, and performing solid-liquid separation to obtain the first linker; (2) mixing the second linker with the first linker, then adding a second catalyst to react, and performing solid-liquid separation after the reaction to obtain a covalent organic framework precursor; (3) mixing the covalent organic framework precursor with a scandium salt to perform a coordination reaction, and performing solid-liquid separation after the reaction to obtain the ratio type rare earth functionalized covalent organic framework fluorescent probe.

3. The production method according to claim 2, characterized by, In step (1), the 1,4-benzenediboronic acid and the 4-bromo-2-hydroxybenzaldehyde are mixed in an organic solvent.

4. The production method according to claim 3, characterized by, The organic solvent comprises any one or a combination of at least two of methanol, ethanol, toluene, tetrahydrofuran or anhydrous acetonitrile.

5. The preparation method according to claim 2, characterized in that, The lye comprises potassium carbonate and / or potassium phosphate.

6. The preparation method according to claim 2, characterized in that, The first catalyst comprises tetrakis(triphenylphosphine)palladium or palladium acetate.

7. The preparation method according to claim 2, characterized in that, In step (1), the reaction is performed under a protective atmosphere; and the temperature of the reaction is 50-80°C.

8. The preparation method according to claim 7, characterized in that, The temperature of the reaction is 60-80°C.

9. The preparation method according to claim 7, characterized in that, The time of the reaction is 12-24h.

10. The method of claim 9, wherein, The time of the reaction is 20h-24h.

11. The method of claim 2, wherein, The adjustment of pH specifically comprises adjusting the pH of the solution to be acidic to generate a precipitate.

12. The method of claim 7, wherein, After the solid-liquid separation, the first linker is obtained through washing and drying.

13. The method of claim 12, wherein, The washing is performed using methanol and water.

14. The method of claim 2, wherein, In step (2), the second linker and the first linker are mixed in an organic solvent.

15. The preparation method according to claim 14, characterized in that, The organic solvent comprises any one or a combination of at least two of 1,4-dioxane, dimethyl sulfoxide or dimethylformamide.

16. The method of claim 2, wherein, The second catalyst comprises acetic acid.

17. The method of claim 2, wherein, In step (2), the reaction is performed under a protective atmosphere; and the temperature of the reaction is 60-120°C.

18. The method of claim 17, wherein, The temperature of the reaction is 90-120°C.

19. The method of claim 17, wherein, The time of the reaction is 3-5d.

20. The method of claim 17, wherein, After the solid-liquid separation, the covalent organic framework precursor is obtained through washing and drying.

21. The method of claim 20, wherein, The washing is performed using tetrahydrofuran and ethanol for at least three times.

22. The method of claim 2, wherein, In step (3), the mass ratio of the covalent organic framework precursor to the scandium salt is 1:(0.5-2).

23. The method of claim 22, wherein, In step (3), the mass ratio of the covalent organic framework precursor to the scandium salt is 1:(0.5-1).

24. The method of claim 2, wherein, The scandium salt comprises any one or a combination of at least two of scandium chloride hexahydrate, scandium nitrate, scandium sulfate and scandium triflate.

25. The method of claim 2, wherein, In step (3), the covalent organic framework precursor and the scandium salt are mixed in an organic solvent.

26. The method of claim 25, wherein, The organic solvent is anhydrous acetonitrile.

27. The method of claim 2, wherein, The temperature of the coordination reaction is 60-80°C; and the time of the coordination reaction is 6-24h.

28. The method of claim 27, wherein, The time of the coordination reaction is 18-24h.

29. The method of claim 25, wherein, After the solid-liquid separation, the ratio type rare earth functionalized covalent organic framework fluorescent probe is obtained through washing and drying.

30. The method of claim 29, wherein, The washing employs anhydrous ethanol rinsing.

31. Use of a fluorescent probe as claimed in claim 1, wherein, The fluorescent probe is used for detecting quinolone antibiotics in water bodies.

32. Use according to claim 31, characterized in that, The quinolone antibiotics include any one or a combination of at least two of enrofloxacin, norfloxacin or perfloxacin.

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