A colorimetric sensor based on bis(pentafluorophenylhydrazone) functionalization for single selective recognition of fluoride ions, and its synthesis and application

Abstract

The present invention provides a colorimetric sensor BPFH based on bis(pentafluorophenylhydrazone) functionalization that can selectively recognize fluoride ions singly. This fluoride ion colorimetric sensor is synthesized from pentafluorophenylhydrazine and terephthalaldehyde. In the DMSO solution of this fluoride ion sensor BPFH, only the addition of fluoride ions can change the color of the sensor BPFH solution from colorless to pink, while other anions (F ‑ , Cl ‑ , Br ‑ , I ‑ , AcO ‑ , H2PO4 ‑ , HSO4 ‑ , ClO4 ‑ , CN ‑ , SCN ‑ , N 3‑ and S 2‑ ) show no response. Therefore, this sensor BPFH has the performance of selectively recognizing fluoride ions singly, with a detection limit of 1.63×10 ‑7 M. The recognition of fluoride ions by this sensor is achieved through hydrogen bonding and anion-π interactions.

Description

Technical Field

[0001] The present invention relates to a synthesis method of a colorimetric sensor based on bis(pentafluorophenylhydrazone) functionalization for highly sensitive and single-selective recognition of fluoride ions; the present invention also relates to the application of this colorimetric sensor in colorimetric recognition of fluoride ions in DMSO solution, belonging to the fields of chemical synthesis and ion detection. Background Art

[0002] Fluorine is the smallest and most electronegative element among the halogens and exists in the environment in the form of fluoride ions. Appropriate amounts of fluoride can protect teeth, prevent dental caries, and promote mineral deposition in bones. However, excessive intake of fluoride can cause dental fluorosis and also affect bone development, leading to skeletal fluorosis. In addition, excessive fluoride in the body can damage the kidneys and liver, and also affect the nervous system and blood system. High concentrations of fluoride ions in the body are prone to causing immune system metabolic disorders, and ultimately lead to abnormal immune function by inhibiting protein and DNA synthesis. In addition to the direct impact on the human body, fluoride pollutants are released into the environment through human activities such as coal combustion, fertilizer use, aluminum smelting, and the production of ceramics, bricks, and glass, posing a threat to the health of the human body and the ecological environment. Excessive fluoride content in the soil can inhibit plant metabolism and photosynthesis, reducing crop yields.

[0003] Common methods for detecting fluoride ions include ion-selective electrode method, ion chromatography, and Willard and Winter method, etc., but most of these methods are costly and operationally complex. Summary of the Invention

[0004] The purpose of the present invention is to provide a colorimetric sensor molecule based on bis(pentafluorophenylhydrazone) functionalization;

[0005] Another purpose of the present invention is to provide a synthesis method of the above colorimetric sensor;

[0006] Another purpose of the present invention is to provide the application of this colorimetric sensor in single-selective recognition of fluoride ions.

[0007] I. Colorimetric Sensor and Its Synthesis

[0008] The colorimetric sensor molecule based on bis(pentafluorophenylhydrazone) functionalization of the present invention has the molecular formula: C 20 H8F 10 N4, labeled as: BPFH, and the structural formula is:

[0009]

[0010] Synthesis method of the colorimetric sensor of the present invention: Using pentafluorophenylhydrazine and terephthalaldehyde as substrates, absolute ethanol as the solvent, reacting at 70-80 °C for 70-75 h. After the reaction, the solution is distilled under reduced pressure to obtain a pale yellow solid, which is recrystallized with ethanol, and the solid obtained by suction filtration is the colorimetric sensor BPFH. Among them, the molar ratio of the substrate terephthalaldehyde to pentafluorophenylhydrazine is 1:2-1:4.

[0011] The synthesis route of the above-prepared colorimetric sensor is as follows:

[0012]

[0013] The mass spectrum and hydrogen spectrum of the sensor molecule BPFH are shown in Figure 1 and Figure 2 .

[0014] II. Application of the colorimetric sensor in detecting fluoride ions

[0015] 1. Luminescence performance of the colorimetric sensor BPFH

[0016] Research on the luminescence performance of the colorimetric sensor BPFH shows that the colorimetric sensor BPFH has good solubility in DMSO solution. Under natural light, the DMSO solution of the sensor molecule BPFH is colorless.

[0017] 2. Recognition of fluoride ions by the colorimetric sensor BPFH

[0018] In the DMSO solution (C BPFH =1×10 -5 M) of the colorimetric sensor BPFH, 50-fold equivalents (relative to the colorimetric sensor BPFH) of 0.1 M F - , Cl - , Br - , I - , AcO - , H2PO4 - , HSO4 - , ClO4 - , CN - , SCN - , N 3- , S 2- aqueous solutions are added respectively, and the color change of the solution is observed. Figure 3 is the fluorescence spectrum diagram of adding different anions to the DMSO solution of the sensor molecule BPFH of the present invention (λ ex= 350 nm). It was found that only the addition of fluoride ions could reduce the fluorescence intensity of the colorimetric sensor BPFH. Under natural light, only the addition of fluoride ions could change the color of the DMSO solution of the colorimetric sensor BPFH from colorless to pink, while the addition of other anions could not change the color of the DMSO solution of the colorimetric sensor BPFH. This indicates that the colorimetric sensor BPFH has a single selective recognition performance for fluoride ions.

[0019] The UV titration experiment showed that the lowest detection limit of the colorimetric sensor BPFH for fluoride ions was 1.63×10 -7 M (as Figure 4 、 5 shown).

[0020] 3. Analysis of the recognition mechanism

[0021] The mechanism of the colorimetric sensor BPFH recognizing fluoride ions was studied by 1H NMR spectra. Different amounts of fluoride ions (prepared in DMSO- d 6 solution) with 0.2, 0.5, 1.0, and 2.0 equivalents were added to the DMSO solution of the host BPFH respectively, and then the changes in the 1H NMR peaks were observed. d 6 Figure 6 Fig. 23 is the 1H NMR titration diagram of the DMSO solution of the sensor molecule BPFH with different volumes (a)-(e): 0, 0.2, 0.5, 1, 2 equivalents of fluoride ions. As 1 can be seen from Figure 6 Fig. 26, with the addition of fluoride ions, the NH peak on BPFH disappeared, and the proton peaks on the aromatic ring shifted to a higher field. This phenomenon indicates that there is a hydrogen bond interaction and an anion-π interaction between the colorimetric sensor BPFH and fluoride ions. Therefore, after the addition of fluoride ions, the color of the DMSO solution of the colorimetric sensor BPFH changed, realizing the single selective recognition of fluoride ions. This is a novel recognition mechanism.

[0022] Meanwhile, the mechanism of the colorimetric sensor BPFH recognizing fluoride ions was studied by 19F NMR spectra. Different amounts of fluoride ions (prepared in DMSO- d 6 solution) with 0.2, 0.5, 1.0, 2.0, and 5.0 equivalents were added to the DMSO solution of the host BPFH respectively, and then the changes in the 19F NMR peaks were observed. d 6 Figure 7 Fig. 38 is the 19F NMR (400 MHZ) titration diagram of the DMSO solution of the sensor molecule BPFH with different volumes (a)-(f): 0, 0.2, 0.5, 1, 2, 5 equivalents of fluoride ions, (g) tetrabutylammonium fluoride. As 19 can be seen from Figure 7 ​​It can be seen that with the addition of fluoride ions, the fluorine on the pentafluorophenyl group shows a high-field shift. This phenomenon indicates that due to the addition of fluoride ions, an anion-π interaction occurs between the fluoride ions and the pentafluorophenyl group of the sensor molecule BPFH, resulting in an increased charge transfer from the NH site to the pentafluorophenyl group, which is consistent with the results obtained from the 1H NMR titration. With the addition of excessive fluoride ions, the fluoride ions deprotonate NH to form HF2 - anions. At the same time, it shows that the fluorine atoms of the fluorophenyl group form hydrogen bond interactions with the HF2 - anions, leading to a low-field shift in the fluorine spectrum of the pentafluorophenyl group again. Brief Description of the Drawings

[0023] Figure 1 is the mass spectrum of the sensor molecule BPFH of the present invention;

[0024] Figure 2 is the 1H NMR spectrum of the sensor molecule BPFH of the present invention;

[0025] Figure 3 is the full-scan curve of different anions added to the DMSO solution of the sensor molecule BPFH of the present invention (λ ex = 345 nm);

[0026] Figure 4 is the UV titration diagram of fluoride ions added to the DMSO solution of the sensor molecule BPFH of the present invention;

[0027] Figure 5 is the lowest detection limit of fluoride ions added to the DMSO solution of the sensor molecule BPFH of the present invention;

[0028] Figure 6 is the 1H NMR spectrum of different volumes of fluoride ions added to the DMSO solution of the sensor molecule BPFH of the present invention;

[0029] Figure 7 is the 19F NMR spectrum of different volumes of fluoride ions added to the DMSO solution of the sensor molecule BPFH of the present invention. Detailed Embodiments

[0030] The preparation of the sensor molecule BPFH of the present invention and its application in colorimetric recognition of fluoride ions will be further described below through specific examples.

[0031] Example 1, Colorimetric Sensor BPFH

[0032] Synthesis of colorimetric sensor BPFH: Weigh 0.25 g (1.26 mmol) of pentafluorophenylhydrazine and 0.074 g (0.55 mmol) of terephthalaldehyde and add them to 50 ml of anhydrous ethanol solvent. React at 75 °C for 72 h. After the reaction, distill the solution under reduced pressure to obtain a pale yellow solid. Recrystallize this crude product with ethanol, and the solid obtained by suction filtration is the colorimetric sensor BPFH. The yield is 74%. The mass spectrum and hydrogen spectrum of the sensor molecule BPFH are shown in Figure 1 and Figure 2 .

[0033] Example 2: Recognition of fluoride ions by colorimetric sensor BPFH

[0034] Pipette 2 mL of the DMSO solution of colorimetric sensor BPFH (C BPFH = 1×10 -5 M) into a series of test tubes, and respectively add aqueous solutions of F - , Cl - , Br - , I - , AcO - , H2PO4 - , HSO4 - , ClO4 - , CN - , SCN - , N 3- , S 2- (C = 0.1 M). If the color of the DMSO solution of the sensor molecule turns pink, it indicates that the added solution is a fluoride ion solution; if the color of the sensor molecule does not change, it indicates that the added solution is not a fluoride ion.

Claims

1. Application of a colorimetric sensor based on bis(pentafluorophenyl)hydrazone functionalization for single selective recognition of fluoride ions in the recognition of fluoride ions, characterized in that: The molecular formula of the colorimetric sensor is C 20 H8F 10 N4, and the structural formula is as follows: 。 2. Use of the colorimetric sensor based on bis(pentafluorophenyl)hydrazone functionalization for single-selective recognition of fluoride ions in the recognition of fluoride ions, characterized in that: In the DMSO solution of the colorimetric sensor molecule BPFH, F - , Cl - , Br - , I - , AcO - , H2PO4 - , HSO4 - , ClO4 - , CN - , SCN - , N 3- , S 2- aqueous solutions are added respectively. Only the addition of fluoride ions can change the color of the DMSO solution of the colorimetric sensor molecule from colorless to pink.

3. Application of the colorimetric sensor based on bis(pentafluorophenyl)hydrazone functionalization for single-selective recognition of fluoride ions in the recognition of fluoride ions, characterized in that: Synthesis method of colorimetric sensor, comprising the following steps: Using pentafluorophenylhydrazine and terephthalaldehyde as substrates, absolute ethanol as solvent, reacting at 70~80 °C for 70~75 h. After the reaction, the solution is distilled under reduced pressure to obtain a pale yellow solid, which is recrystallized with ethanol, and the solid obtained by suction filtration is the colorimetric sensor BPFH.

4. Use of the colorimetric sensor based on bis(pentafluorophenyl)hydrazone functionalization for single-selective recognition of fluoride ions in the recognition of fluoride ions, characterized in that: The molar ratio of terephthalaldehyde to pentafluorophenylhydrazine is 1:2~1:4.

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