A rapid test for low pH and IO3 - Fluorescent polymer probe and its preparation method and application

Abstract

The present invention discloses a method for rapidly detecting low pH and IO3 ‑ The fluorescent polymer probe DAPF and its preparation method and application are as follows: during the preparation, 4-ammonia-4,4-dibromotriphenylamine and 4,5-diazafluorene are firstly reacted to obtain compound M1 through dehydration condensation; compound M1 is then reacted with 2,7-bis(4,4,5,5-tetramethyl-1,3-dioxy-2-borane)-9,9-dibutyric acid ethyl ester-fluorene to obtain the fluorescent polymer probe DAPF; when used, the fluorescent polymer probe DAPF of the present invention can quickly realize low pH and IO3 in solution and thin film fluorescence sensor. ‑ The detection has the advantages of high selectivity, high sensitivity, good safety, good stability, low cost, simple operation, and does not require complex synthesis processes and expensive instruments. It effectively improves the problems of high cost, low stability and complex material synthesis process of existing technologies.

Description

Technical Field

[0001] The present invention relates to the field of fluorescent probe technology, specifically a method for rapidly detecting low pH and IO3 - Fluorescent polymer probe and its preparation method and application. Background Art

[0002] pH is a critical parameter controlling many chemical and physiological processes, and is used in a variety of applications, including environmental analysis, chemical process control, food production, and medical diagnostics. Currently, various methods for pH measurement exist, including electrochemistry, NMR, and optical pH sensors. Compared to other technologies, optical pH sensors offer numerous advantages, including low cost, fast response time, simple operation, high stability, high sensitivity, the absence of a reference electrode, and the potential for real-time sensing. Optical pH sensors typically operate by measuring pH-dependent optical properties, including absorbance, reflectance, and fluorescence. Among these optical methods, fluorescent pH sensors have garnered considerable attention due to their high sensitivity. However, most fluorescent pH sensors are suitable for use in the pH range (4-8) or the weakly acidic pH range (2-4). Fluorescent probes for use in the strongly acidic pH region (<2) have received relatively little attention. However, low-pH sensors hold great practical value, as some media, such as those found in the human stomach and other environments, are highly acidic. Conventional pH glass electrodes are unsuitable for use under these conditions. Therefore, the development of responsive optical pH sensors capable of detecting low pH is an attractive area of ​​research.

[0003] Iodine is an essential micronutrient for life. Iodine deficiency can lead to a range of health problems, including hypothyroidism, cretinism, and spontaneous abortion. The US National Research Council recommends that adults consume 150 μg of iodine daily. The most effective treatment for iodine deficiency is the addition of potassium iodate to salt. Therefore, the detection of iodate content in salt is of research interest. To date, iodate detection has been performed using resonance scattering spectroscopy, ion chromatography, and electrochemical sensors. However, due to the high cost and complexity of the operation, the use of fluorescence sensors for iodate detection has drawn attention. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for rapid detection of low pH and IO3, which is suitable for most fluorescent pH sensors in the pH (4-8) region or weakly acidic pH (2-4) conditions, while the currently commonly used pH glass electrodes are not suitable for use under special conditions, and the detection of iodate by resonance scattering spectroscopy, ion chromatography and electrochemical sensors has problems such as high cost and complexity. - Fluorescent polymer probe and its preparation method and application.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention provides a method for rapidly detecting low pH and IO3 - The fluorescent polymer probe DAPF has the following repeating structural units:

[0007]

[0008] Where n=10-20.

[0009] The present invention also provides a method for rapidly detecting low pH and IO3 - The synthesis method of the fluorescent polymer probe DAPF comprises the following steps:

[0010] (1) 4-Amino-4,4-dibromotriphenylamine, 4,5-diazafluorene, a catalyst, and toluene were placed in a reaction vessel and reacted at 80-90° C. under an inert gas atmosphere for 16-24 hours. After the reaction was completed, the mixture was cooled to room temperature and the organic solvent was removed by distillation. The crude product was purified by column separation to obtain compound M1. The synthetic route is as follows:

[0011]

[0012] This reaction is a typical dehydration condensation reaction;

[0013] (2) The above compound M1 and 2,7-bis(4,4,5,5-tetramethyl-1,3-dioxo-2-borane)-9,9-dibutyric acid ethyl ester-fluorene were dissolved in DMF, and then the catalyst and K2CO3 solution were added in sequence. The temperature was maintained at 100-120°C under the protection of an inert atmosphere, and the reaction was carried out for 44-52 hours. After the reaction was completed, the mixture was cooled to room temperature and poured into an appropriate amount of ethanol. The mixture was stirred, filtered, washed, and dried to obtain the fluorescent polymer probe DAPF. The synthesis route is as follows:

[0014]

[0015] This reaction is a typical Suzuki coupling reaction.

[0016] The fluorescent polymer probe DAPF provided by the present invention can detect pH and exhibits significant fluorescence enhancement. This is because the triphenylamine in the polymer DAPF and the nitrogen atom in the pyridine ring are protonated, inhibiting the PET process and leading to fluorescence enhancement.

[0017] The fluorescent polymer probe DAPF provided by the present invention can also achieve IO3 - The recognition of IO3 - With H + The binding forms iodic acid, which causes the PET process to occur, resulting in fluorescence quenching.

[0018] Preferably, in step (1), the molar ratio of 4-ammonia-4,4-dibromotriphenylamine to 4,5-diazafluorene is (1-1.2):1; the mass of the catalyst is 1%-5% of 4-ammonia-4,4-dibromotriphenylamine or 4,5-diazafluorene, and the catalyst is one of p-toluenesulfonic acid, acetic acid, and trifluoromethanesulfonic acid.

[0019] Preferably, in step (2), the molar ratio of compound M1 to 2,7-bis(4,4,5,5-tetramethyl-1,3-dioxo-2-borane)-9,9-dibutyric acid ethyl ester-fluorene is 1:(0.9-1.1).

[0020] The present invention also provides a method for rapidly detecting low pH and IO3 - The fluorescent polymer probe DAPF is used in pH detection. After adjusting the pH to 1 in the DMSO:H2O (5:1, v / v) solution of the fluorescent polymer probe DAPF, the fluorescence of the solution is significantly enhanced, and the color changes from colorless to bright blue under 365nm ultraviolet light.

[0021] The present invention also provides a method for rapidly detecting low pH and IO3 - The fluorescent polymer probe DAPF is used to detect IO3 - Application in DAPF-H + Add IO3 - The fluorescence of the solution was quenched, and the color changed from bright blue to colorless under 365nm ultraviolet light.

[0022] Preferably, the IO3 - The detection limit was 3×10 -8 M.

[0023] The present invention also provides a method for rapidly detecting low pH and IO3 - The fluorescent polymer probe DAPF was used as a hydrogel film sensor. The fluorescent polymer probe DAPF was combined with polyvinyl alcohol to make a hydrogel film device. Under a 365nm ultraviolet light, the pH and IO3 in the solution were quickly and conveniently detected by "naked eyes". - Detection.

[0024] The present invention also provides a method for rapidly detecting low pH and IO3 - The fluorescent polymer probe DAPF was used as a hydrogel film sensor. Three parts of polyvinyl alcohol were weighed and added to an organic solvent and water. After stirring and dissolving, fluorescent polymer probes DAPF and DAPF-H were added respectively and the pH of the solution was adjusted to 1. + Join IO3 -, cooled to room temperature to obtain a hydrogel film sensor, and the three hydrogel film sensors obtained were placed under a 365nm ultraviolet lamp, and the color change of the hydrogel film sensor was detected by "naked eyes".

[0025] The fluorescent polymer probe DAPF provided by the present invention can quickly realize the low pH and IO3 - The fluorescent polymer has the advantages of high selectivity, high sensitivity, good safety, good stability, low cost, simple operation, and does not require complex synthesis processes and expensive instruments. It effectively improves the problems of high cost, low stability and complex material synthesis process of existing technologies.

[0026] Figures in the specification

[0027] Figure 1 The fluorescent probes DAPF and DAPF-H prepared in Example 1 + Infrared spectrum of

[0028] Figure 2 The fluorescence spectra of the fluorescent probe DAPF prepared in Example 1 in DMSO:H2O (5:1, v:v) at different pH values;

[0029] Figure 3 : This is the fluorescence response graph of the fluorescent probe DAPF prepared in Example 1 for pH selective interference detection in DMSO:H2O (5:1, v:v);

[0030] Figure 4 This is a graph showing the anion-selective fluorescence spectrum of the fluorescent probe DAPF prepared in Example 1 in DMSO:H2O (5:1, v:v, pH=1);

[0031] Figure 5 The fluorescent probe DAPF prepared in Example 1 was dissolved in DMSO:H2O (5:1, v:v, pH=1) along with IO3 - Fitting curve of fluorescence intensity with increasing concentration;

[0032] Figure 6 The fluorescent probes DAPF and DAPF-H prepared in Example 1 + DAPF-H + +IO3 - Image of a thin film sensor under 365nm UV light. DETAILED DESCRIPTION

[0033] In order to better explain the present invention and facilitate understanding of the technical solution of the present invention, it is now further described in conjunction with the drawings and embodiments. It should be understood that the specific embodiments of the present invention are only for illustrative purposes and are not intended to limit the present invention.

[0034] Example 1

[0035] A rapid detection method of low pH and IO3 in this embodiment - The synthesis method of the fluorescent polymer probe DAPF is as follows: 4-amino-4,4-dibromotriphenylamine (0.6 g, 1.44 mmol), 4,5-diazafluorene (0.2166 g, 1.2 mmol), and p-toluenesulfonic acid (0.0207 g, 0.12 mmol) are weighed and dissolved in toluene (25 mL), placed in a 50 mL round-bottom flask, and kept at 90°C under an argon atmosphere for 18 hours. After the reaction is completed, it is cooled to room temperature and the toluene is removed by a rotary evaporator. The crude product is purified by silica gel chromatography to obtain compound M1. The structure of M1 can be found in step (1) in the specification. The results of the H NMR spectrum of M1 are as follows: 1H NMR (400MHz, CDCl3) δ8.81 (dd, J=5.0, 1.6Hz, 1H), 8.70 (dd, J=4.9, 1.6Hz, 1H), 8.24 (dd, J=7.6, 1.6Hz, 1H),7.42–7.37(m,5H),7.25(s,1H),7.15(d,J=8.8Hz,2H),7.10–7.06(m,1H),7.02–6.94(m,6H).13CNM R(101MHz, CDCl3)δ161.66,159.81,158.23,153.31,152.74,146.39,146.26,144.28,133.47,132.62,1 32.54,132.12,130.52,125.42,125.32,124.29,124.23,123.18,120.19,115.78,77.25.IR(KBr):v(cm -1 )2965(CN),1596(C=N),566(C-Br).HRMS(ESI+,m / z)calculatedforC 29 H 18 Br2N4(M+4H) + :583.0132,found:582.9964.

[0036] The obtained M1 (0.2900 g, 0.5 mmol), 2,7-bis(4,4,5,5-tetramethyl-1,3-dioxo-2-borane)-9,9-dibutyric acid ethyl ester-fluorene (0.3231 g, 0.5 mmol), Pd(Phh3)4 (10 mg), and 2MK2CO3 (2 mL) were dissolved in 10 mL of DMF. The mixture was stirred in an oil bath at 100°C under an argon atmosphere for 48 h. After the reaction, it was cooled to room temperature and 100 mL of ethanol was added to precipitate a red solid. The solid was washed with deionized water and dried to obtain a crude polymer product. The crude product was Soxhlet extracted with petroleum ether, acetone, ethanol, and methanol for 12 h. Finally, the methanol solution was concentrated and evaporated to dryness to obtain the fluorescent polymer probe DAPF. The results of hydrogen nuclear magnetic resonance spectrum of DAMF are as follows: 1H NMR (400 MHz, CDCl3) δ (ppm): 8.81-8.13 (diazafluorene, Ph-H), 7.83-7.51 (triphenylamine, Ph-H), 7.36-7.17 (fluorene, Ph-H), 2.28-1.93 (-CH2), 1.33-1.09 (-CH3). IR (KBr): v (cm-1) 2916 (CN), 1513 (C=O), 1465 (CO), 1596 (C=N).

[0037] The surface functional groups of the fluorescent polymer probe DAPF prepared in Example 1 were analyzed by infrared spectroscopy. Figure 1 As shown. Figure 1 It can be seen that at 2916cm -1 The characteristic absorption peak of CN is 1596 cm -1 The characteristic absorption peak of C=N is 1513cm -1 The characteristic absorption peak of C=O is located at , which proves that the fluorescent polymer probe DAPF of the present invention is successfully synthesized.

[0038] The fluorescent polymer probe DAPF prepared in this example can quickly detect a strong acidic environment with a pH value less than 2, and can also detect IO3 in an acidic environment. - Identification of DAPF-H + Fluorescence intensity and IO3 - There is a good linear relationship, IO3 - The detection limit was 3×10 -8 M.

[0039] Example 2

[0040] To evaluate the performance of the fluorescent polymer probe DAPF at different pH values, its performance in DMSO:H2O (5:1, v:v) was verified. + The selectivity, Figure 2 It is a fluorescent polymer probe DAPF (1×10 -5 mol / L) at pH = 0-14 (λex = 360nm; slit ex / em = 10.0nm / 10.0nm). Figure 2 It can be seen that when pH = 0, there is no obvious change in fluorescence. As the pH increases, the fluorescence increases significantly when pH = 1, and then the fluorescence is completely quenched at pH = 3. The results show that the fluorescent probe DAPF is highly selective for strong acidity at pH = 1.

[0041] Anti-interference performance is another important indicator to measure an excellent sensor. Figure 3 It is H + The fluorescence intensity histogram in the presence of different interfering ions. Figure 3 It can be seen that the fluorescent polymer probe DAPF (1×10 -5 mol / L) were added with a concentration of 2×10 -5 mol / L of different metal ions (Na + Mg 2+ , Ca 2+ 、Cd 2+ Cr 3+ 、Li + 、Ba 2+ 、Mn 2+ , K + 、Fe 2+ 、Fe 3+ 、Co 2+ 、Ni 2+ 、Cu 2+ 、Sr 2+ 、Al 3+ 、Ag + 、Zn 2+ 、Hg 2+ , Pb 2+ ) and adjusted the solution pH to 1 in the presence of the aforementioned interfering ions, and measured its fluorescence intensity (λex = 360 nm; slit ex / em = 10.0 / 10.0 nm). The results showed that when the solution pH was adjusted to 1, the fluorescent probe DAPF exhibited a significant fluorescence enhancement. Furthermore, when the solution pH was adjusted to 1 in the presence of common interfering substances, the fluorescence response was largely unaffected. This demonstrates the excellent anti-interference performance of the fluorescent probe DAPF.

[0042] Example 3

[0043] This example also tested the selectivity of the fluorescent polymer probe DAPF with anions at pH = 1. Figure 4As shown. The fluorescent probe DAPF (1×10 -5 mol / L) and adjust the solution pH to 1, add 2×10 -5 mol / L of different anions (Br - , ClO3 - , CN - , SO4 2- , H2PO4 - , HSO3 - , I - , IO3 - , NO2 - , S 2- , S2O8 2- ) were tested. The results showed that in addition to adding NO2 - , HSO3 - and ClO3 - When IO3 is added, the fluorescence intensity of the solution will decrease slightly. - When , the fluorescence intensity of the system was significantly quenched, while other anions did not cause significant changes in the fluorescence intensity of the system, indicating that the fluorescent probe DAPF has a strong effect on IO3 - Has good selectivity.

[0044] In addition, the fluorescent polymer probe DAPF was also used to detect IO3 in DMSO:H2O (5:1, v:v, pH=1). - To perform the quantitative analysis, 3 μL of 1×10 -2 moL / L fluorescent polymer probe DAPF and a concentration of 1×10 -2 io3 in moL / L - Solution (0μL-9μL) was tested, and the experimental results were as follows Figure 5 As shown, the fluorescent polymer probe DAPF has bright blue fluorescence in DMSO:H2O (5:1, v:v, pH=1), but - As the concentration increases, the fluorescence at 476nm increases with the increase of IO3 - The solution color changes from bright blue to colorless as the concentration of IO3 increases. - The concentration of the fluorescent probe DAPF is in the range of 3.2-4.4 μM. - The concentration showed a good linear relationship (R 2 =0.992), according to the detection limit formula: LOD = 3σ / k (where σ is the standard deviation and k is the slope of the line), the detection limit is calculated to be 3×10 -8M, indicating that the fluorescent probe DAPF is sensitive to IO3 - The recognition has higher sensitivity.

[0045] Example 4

[0046] For portability, the fluorescent polymer probe DAPF of the present invention can also be used as a thin film fluorescence sensor. The thin film sensor prepared in this embodiment is as follows: Figure 6 As shown, 0.0125 g of polyvinyl alcohol was weighed and added to 5 mL of DMSO:H2O (5:1), stirred to dissolve, and 1×10 -2 mol / L fluorescent polymer probe DAPF was placed in a mold and cooled to room temperature to obtain a hydrogel film sensor. Under a 365nm ultraviolet light, the fluorescent polymer probe DAPF had no fluorescence. When the pH was adjusted to 1, DAPF-H + It has bright blue fluorescence under 365nm ultraviolet light, and IO3 is added - The fluorescence disappears. The results show that the fluorescent probe DAPF can be used as an acid detection sensor with the advantages of portability and simple operation.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A rapid test for low pH and IO3 - The fluorescent polymer probe DAPF is characterized by: Its repeating structural units are as follows: Where n=10-20.

2. A rapid detection method for low pH and IO3 as claimed in claim 1 - The method for synthesizing the fluorescent polymer probe DAPF is characterized in that: Its synthetic route is as follows:

3. A rapid detection method for low pH and IO according to claim 2 - The method for synthesizing the fluorescent polymer probe DAPF is characterized in that: The specific synthesis steps are as follows: (1) 4-Amino-4,4-dibromotriphenylamine, 4,5-diazafluorene, a catalyst, and toluene were placed in a reaction vessel and reacted at 80-90° C. under an inert gas for 16-24 hours. After the reaction was completed, the mixture was cooled to room temperature and the organic solvent was removed by distillation. The crude product was purified by column separation to obtain compound M1; (2) Compound M1 and 2,7-bis(4,4,5,5-tetramethyl-1,3-dioxo-2-borane)-9,9-dibutyric acid ethyl ester-fluorene were dissolved in DMF, and then catalyst and K2CO3 solution were added in sequence. The temperature was maintained at 100-120°C under the protection of inert atmosphere, and the reaction was carried out for 44-52 hours. After the reaction was completed, the mixture was cooled to room temperature and poured into an appropriate amount of ethanol. The mixture was stirred, filtered, washed, and dried to obtain the fluorescent polymer probe DAPF.

4. A rapid detection method for low pH and IO according to claim 3 - The method for synthesizing the fluorescent polymer probe DAPF is characterized in that: In the step (1), the molar ratio of 4-ammonia-4,4-dibromotriphenylamine to 4,5-diazafluorene is (1-1.2):1; the mass of the catalyst is 1%-5% of 4-ammonia-4,4-dibromotriphenylamine or 4,5-diazafluorene, and the catalyst is one of p-toluenesulfonic acid, acetic acid, and trifluoromethanesulfonic acid.

5. A rapid detection method for low pH and IO according to claim 3 - The method for synthesizing the fluorescent polymer probe DAPF is characterized by: In the step (2), the molar ratio of compound M1 to 2,7-bis(4,4,5,5-tetramethyl-1,3-dioxo-2-borane)-9,9-dibutyric acid ethyl ester-fluorene is 1:(0.9-1.1).

6. A rapid detection method for low pH and IO3 as claimed in claim 1 - The application of the fluorescent polymer probe DAPF in detecting pH is characterized by: After adjusting the pH value to 1 in the DMSO:H2O (5:1, v / v) solution of the fluorescent polymer probe DAPF, the fluorescence of the solution was significantly enhanced, and the color changed from colorless to bright blue under 365nm ultraviolet light.

7. A rapid detection method for low pH and IO3 as claimed in claim 1. - The fluorescent polymer probe DAPF is used to detect IO3 - The application is characterized by: In DAPF-H + Add IO3 - The fluorescence of the solution was quenched, and the color changed from bright blue to colorless under 365nm ultraviolet light.

8. A rapid detection method for low pH and IO3 according to claim 7. - The fluorescent polymer probe DAPF is used to detect IO3 - The application is characterized by: IO3 - The detection limit was 3×10 -8 M.

9. A rapid detection method for low pH and IO3 as claimed in claim 1 - The application of the fluorescent polymer probe DAPF as a hydrogel film sensor is characterized in that: The fluorescent polymer probe DAPF and polyvinyl alcohol were used to make a hydrogel film device, which can quickly and conveniently detect the pH and IO3 in the solution with the naked eye under a 365nm ultraviolet lamp. - Detection.

10. A rapid detection method for low pH and IO3 according to claim 9. - The application of the fluorescent polymer probe DAPF as a hydrogel film sensor is characterized by: Weigh 3 parts of polyvinyl alcohol and add organic solvent and water, stir and dissolve, then add fluorescent polymer probe DAPF, fluorescent polymer probe DAPF and adjust the pH of the solution to 1 and DAPF-H + Join IO3 - , cooled to room temperature to obtain a hydrogel film sensor, and the three obtained hydrogel film sensors were placed under a 365nm ultraviolet lamp, and the color change of the hydrogel film sensor was detected by "naked eyes".

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