Fluorine-containing squarylium cyanine near-infrared absorption dye for zinc ion detection and preparation method thereof

Abstract

The invention discloses a fluorine-containing squarylium cyanine near-infrared absorption dye and a preparation method thereof. The chemical structural formula of the fluorine-containing squarylium cyanine near-infrared absorption dye is shown in the specification. The dye is of a D-A-D type molecular structure, has enough low absorbance in a visible wavelength region of 400-750 nm, and has enough high absorbance in a near-infrared wavelength region of 750-1000 nm, so that the dye can be used for zinc ion colorimetric response and qualitative and quantitative detection based on near-infrared light absorption.

Description

Technical Field

[0001] This invention belongs to the field of near-infrared absorption dye preparation technology, specifically relating to a fluorinated squaric acid cyanine near-infrared absorption dye for zinc ion detection and its preparation method. Background Technology

[0002] Near-infrared absorbing dyes refer to dyes with absorption wavelengths between 780 and 2526 nm. Based on their chemical structure, they can be classified into cyanine dyes, metal complex dyes, BODIPY dyes, squaric acid cyanine dyes, and phthalocyanine dyes, among others. Among these, squaric acid cyanine dyes have received widespread attention in the near-infrared field due to their unique optical properties and structural characteristics.

[0003] Squamousine is a dye with a zwitterionic resonance structure, exhibiting strong absorption and fluorescence emission in the visible and near-infrared regions, with a narrow band gap. Its core structure is a strong electron-withdrawing group, making it susceptible to attack by electron-rich nucleophiles such as thiols, F⁻, and CN⁻, leading to changes in the conjugated structure and consequently alterations in color and fluorescence emission. While squamousine dyes have been developed into colorimetric probes for the identification of divalent copper, trivalent iron, and divalent mercury ions, their application to zinc ion identification is not yet observed. This is because there is currently no effective method for detecting zinc ions, and its absorption peak in the visible light region is easily interfered with by colored impurities. Summary of the Invention

[0004] The purpose of this invention is to provide a fluorinated near-infrared absorbing dye for zinc ion detection and its preparation method. The dye has a DAD-type molecular structure, with sufficiently low absorbance in the visible wavelength region of 400-750 nm and sufficiently high absorbance in the near-infrared wavelength region of 750-1000 nm. It can realize colorimetric recognition response and qualitative and quantitative detection of zinc ions based on near-infrared light absorption, and its preparation is simple.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: One objective of this invention is to protect a fluorinated squaric acid cyanine near-infrared absorbing dye, the chemical structural formula of which is: This dye contains six fluorine atoms, whose intermolecular interactions are suppressed, and its particles have high crystallinity, thus giving it excellent near-infrared color development and lightfastness.

[0006] The second objective of this invention is to protect the preparation method of the fluorinated squaric acid cyanine near-infrared absorbing dye, the reaction flow of which is as follows: Specifically, it includes the following steps: 1) Preparation of intermediate product: At room temperature, 1,8-diaminonaphthalene, acid catalyst, 2,2,2-trifluoroacetophenone and dehydrating solvent are mixed and subjected to azeotropic dehydration reaction under nitrogen protection. After the reaction is completed, the mixture is cooled to room temperature, and the reaction solution is purified by concentration, column chromatography or recrystallization to obtain the intermediate product 2-phenyl-2-trifluoromethyl-2,3-dihydropyridine. 2) Preparation of fluorinated near-infrared absorbing dye: At room temperature, 2-phenyl-2-trifluoromethyl-2,3-dihydropyridine, squaric acid and solvent obtained in step 1) are mixed and subjected to azeotropic dehydration reaction under nitrogen protection. After the reaction is completed, the mixture is cooled to room temperature, the reaction solution is filtered to obtain a solid product, and the obtained solid product is washed with ethyl acetate to obtain the fluorinated near-infrared absorbing dye.

[0007] Further, the molar ratio of 1,8-diaminonaphthalene, acid catalyst and 2,2,2-trifluoroacetophenone used in step 1) is 1:(0.01~0.1):1.

[0008] Further, the acid catalyst mentioned in step 1) is any one of p-toluenesulfonic acid monohydrate, benzenesulfonic acid monohydrate, 4-chlorobenzenesulfonic acid, pyridine-3-sulfonic acid, ethanesulfonic acid, sulfuric acid, nitric acid, and acetic acid.

[0009] Further, the dehydrating solvent in step 1) is any one of aromatic hydrocarbons or cycloalkanes. Optionally, the aromatic hydrocarbon is any one of benzene, toluene, xylene, or monochlorobenzene; the cycloalkanes are any one of cyclohexane, methylcyclohexane, or cycloheptane.

[0010] Furthermore, the temperature of the azeotropic dehydration reaction described in step 1) is 80~160 ℃, and the time is 5~15 h.

[0011] Furthermore, in step 2), the molar ratio of 2-phenyl-2-trifluoromethyl-2,3-dihydropyridine and squaric acid is 2:1 to 2.5:1.

[0012] Further, the solvent mentioned in step 2) is an alcohol, or a mixture of an alcohol with any one of aromatic hydrocarbons, cycloalkanes, ethers, halogenated hydrocarbons, or amides. Optionally, the alcohol is any one of 1-propanol, 2-propanol, 1-butanol, and 1-pentanol; the aromatic hydrocarbon is any one of benzene, toluene, xylene, and monochlorobenzene; the cycloalkanes are any one of cyclohexane, methylcyclohexane, and cycloheptane; the ethers are any one of tetrahydrofuran and dioxane; the halogenated hydrocarbons are any one of chloroform, dichloroethane, trichloroethane, and dichloropropane; and the amides are any one of N,N-dimethylformamide and N,N-dimethylacetamide.

[0013] More specifically, the solvent used in step 2) may be 1-propanol, 2-propanol, 1-butanol, 2-butanol, a mixed solvent of 1-propanol and benzene, a mixed solvent of 1-propanol and toluene, a mixed solvent of 1-propanol and cyclohexane, a mixed solvent of 1-propanol and methylcyclohexane, a mixed solvent of 1-propanol and N,N-dimethylformamide, a mixed solvent of 2-propanol and benzene, a mixed solvent of 2-propanol and toluene, a mixed solvent of 2-propanol and cyclohexane, a mixed solvent of 2-propanol and methylcyclohexane, or 2-propanol... Mixed solvents of N,N-dimethylformamide, mixed solvents of 1-butanol and benzene, mixed solvents of 1-butanol and toluene, mixed solvents of 1-butanol and cyclohexane, mixed solvents of 1-butanol and methylcyclohexane, mixed solvents of 1-butanol and N,N-dimethylformamide, mixed solvents of 2-butanol and benzene, mixed solvents of 2-butanol and toluene, mixed solvents of 2-butanol and cyclohexane, mixed solvents of 2-butanol and methylcyclohexane, and mixed solvents of 2-butanol and N,N-dimethylformamide.

[0014] Furthermore, when using a mixed solvent, the volume percentage of alcohols is preferably 1% or more, more preferably 5% to 75%.

[0015] Furthermore, the temperature of the azeotropic dehydration reaction described in step 2) is 100~160 ℃, and the time is 3~6 h.

[0016] Furthermore, the reaction temperature varies depending on the type of solvent used. However, the temperature of the reaction solution is preferably 60°C or higher, more preferably 75°C or higher. For example, when using a mixed solvent of 1-butanol and toluene, the temperature of the reaction solution can be set in the range of 75°C to 105°C. Simultaneously, the reaction time also varies depending on the type of solvent or the temperature of the reaction solution. For example, when using a mixed solvent of 1-butanol and toluene and setting the temperature of the reaction solution in the range of 90°C to 105°C, the reaction time can be 2 to 4 hours.

[0017] Furthermore, a dehydrating agent may be used in step 2) to shorten the reaction time. The type of dehydrating agent is not specifically limited, as long as it does not react with the intermediate product or with squaric acid. Specifically, the dehydrating agent may be orthoformate esters such as trimethyl orthoformate, triethyl orthoformate, tripropyl orthoformate, and tributyl orthoformate; and molecular sieves.

[0018] A third objective of this invention is to protect the application of the fluorinated squaric acid cyanine near-infrared absorbing dye in the detection of zinc ions.

[0019] Furthermore, the fluorinated squaric acid cyanine near-infrared absorbing dye can be used to prepare a chemical sensor for the identification and detection of zinc ions in solution.

[0020] The beneficial effects of this invention are as follows: The fluorinated squaric acid cyanine near-infrared absorbing dye prepared by this invention has sufficiently low absorbance in the visible wavelength region of 400~750 nm and sufficiently high absorbance in the near-infrared wavelength region of 750~1000 nm. Therefore, it can realize the colorimetric response of zinc ions based on near-infrared light absorption. The chemical sensor prepared using it has excellent optical performance and advantages such as high sensitivity and good selectivity. It can be used for the qualitative and quantitative determination of zinc ions in solution. Attached Figure Description

[0021] Figure 1 The visible to near-infrared absorption spectrum of the fluorinated squaric acid cyanine near-infrared absorbing dye prepared as an example in tetrahydrofuran solution.

[0022] Figure 2 The powder X-ray diffraction spectrum of the fluorinated squaric acid cyanine near-infrared absorbing dye prepared as an example.

[0023] Figure 3 The visible to near-infrared absorption spectrum is shown in the N,N-dimethylformamide solution containing fluorosquamousine near-infrared absorbing dye after the addition of zinc acetate.

[0024] Figure 4 To add zinc acetate and five other metal ions (K+, K+, K+) to a solution of N,N-dimethylformamide containing fluorosquaric acid cyanine near-infrared absorbing dye. + Ca 2+ Mn 2+ Co 2+ Mg 2+ The visible to near-infrared absorption spectrum after ( ).

[0025] Figure 5 The visible to near-infrared absorption spectrum of the fluorine-free squaricine near-infrared absorbing dye prepared as a comparative example in tetrahydrofuran solution.

[0026] Figure 6 The visible to near-infrared absorption spectrum of N,N-dimethylformamide solution containing fluorine-free squaric acid cyanine near-infrared absorbing dye is shown.

[0027] Figure 7 The graph shows a comparison of the normalized maximum absorbance (750–850 nm) of the fluorinated squaric acid cyanine near-infrared absorbing dye prepared in the example and the fluorine-free squaric acid cyanine near-infrared absorbing dye prepared in the comparative example with the zinc acetate concentration. Detailed Implementation

[0028] To facilitate understanding of the present invention, it will be described in more detail below through embodiments and comparative examples. However, the present invention is by no means limited to the following examples.

[0029] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0030] Examples include fluorinated squaric acid cyanine near-infrared absorbing dyes ( Preparation of ) 5.062 g of 1,8-diaminonaphthalene (98%, 32.0 mmol), 5.572 g of 2,2,2-trifluoroacetophenone (98%, 32.0 mmol), 182.6 mg of p-toluenesulfonic acid monohydrate (0.96 mmol), and 50 mL of toluene were stirred and mixed. The mixture was then heated to 110 °C under a nitrogen atmosphere and refluxed for 10 hours (water generated during the reaction was removed by azeotropic distillation). After the reaction was complete, the toluene was evaporated, and the resulting dark brown oily substance was purified by silica gel column chromatography. A mixture of PE (petroleum ether) and EA (ethyl acetate) (6:1, V / V) was used as the eluent. The desired product eluent was collected by thin-layer chromatography analysis. After removing the solvent by rotary evaporation, the product was dried under vacuum (60 °C) to obtain an orange-yellow oily liquid, which was 2-phenyl-2-trifluoromethyl-2,3-dihydropeptididine, with a yield of 7.42 g and a yield of 73.8%.

[0031] 4.150 g of 2-phenyl-2-trifluoromethyl-2,3-dihydropeptidyl (13.2 mmol), 0.685 g of squaric acid (6.0 mmol), 15 mL of n-butanol, and 45 mL of toluene were stirred and mixed, then heated to 105 °C under a nitrogen atmosphere and refluxed for 4.5 hours (water generated during the reaction was removed by azeotropic distillation). After the reaction was complete, most of the solvent was evaporated under a nitrogen atmosphere, and then a small amount of ethyl acetate was added to the resulting reaction mixture with stirring, resulting in a dark green precipitate. The resulting dark green precipitate was collected by suction filtration, washed with a small amount of ethyl acetate, and dried under vacuum (60 °C) to obtain a dark green solid product with a yield of 2.43 g, representing a yield of 54.7%.

[0032] The obtained dye compounds were analyzed by infrared absorption spectroscopy (reflectance method). 1 H-NMR (DMSO-d6), 19 Identification was performed using spectroscopic methods including DMSO-d6 NMR spectroscopy, MALDI-TOF-MS, and visible to near-infrared absorption spectroscopy. The identification data are shown below: Infrared absorption spectroscopy (reflectance method): v max=3736, 3443(NH), 3058, 2923, 2358, 2337, 2113, 1610, 1572, 1541, 1516(C=C ring), 1456, 1418, 1354, 1315, 1279, 1225, 1190(CN), 1157, 1132(CO) - ), 1090, 1063, 999, 967, 936, 907, 841, 818, 780, 753,687, 668, 618 cm -1 .

[0033] 1 H-NMR spectrum (DMSO-d6): δ =11.65(br s, 2H, NH); 8.83(br s, 2H, NH); 7.91, 7.88, 7.86(m, 3H, H arom ); 7.72, 7.71, 7.68 (m, 4H, H) arom ); 7.52, 7.50, 7.48, 7.38, 7.25, 7.23, 7.18, 7.16(m, 9H, H arom ); 7.03, 7.01, 6.96, 6.94(m, 4H, H arom ) ppm.

[0034] 19 F-NMR spectrum (DMSO-d6): δ =─78.04, ─78.39, ─79.05, ─79.21 (m, 3F, CF3)ppm.

[0035] Mass spectrometry (MALDI-TOF-MS): m / z = 706.275 (M + (100%), calculated molecular weight: 706.180.

[0036] Visible to near-infrared absorption spectra, such as Figure 1 , its λ max =799 nm, ε max =1.5×10 5 M -1 cm -1 .

[0037] X-ray diffraction measurements were performed using a Cu target and an X-ray diffractometer. For example... Figure 2In the powder X-ray diffraction spectrum, it has diffraction peaks at at least 2θ = 9.6°, 10.4°, 13.5°, 15.3°, 16.0°, 17.0°, 17.4°, 19.4°, 20.2°, 22.1°, 22.5°, 23.2°, 23.6°, 24.3°, 25.4° and 27.8° (2θ ± 0.2°), and is in the form of crystalline particles.

[0038] To test the recognition performance of the prepared fluorinated squaric acid cyanine near-infrared absorbing dye for zinc ions, N,N-dimethylformamide was used as a solvent to formulate the synthesized fluorinated squaric acid cyanine near-infrared absorbing dye to a concentration of approximately 0.5 (concentration 3.6 × 10⁻⁶) with a maximum absorbance in the near-infrared region. -5 After measuring the absorption spectrum of a solution containing mol / L zinc acetate, 5 mg, 10 mg, 15 mg, 30 mg, 45 mg, and 60 mg of zinc acetate dihydrate were added to 3.3 mL of this solution, respectively. After thorough mixing, the changes in the visible to near-infrared absorption spectra were measured sequentially. The results are as follows: Figure 3 As shown. By Figure 3 It can be seen that the addition of zinc ions to the N,N-dimethylformamide solution of the fluorosquamousine near-infrared absorbing dye significantly increases the maximum absorbance at 805 nm, indicating that it has excellent recognition performance for zinc ions.

[0039] To further test the anti-interference performance of the prepared fluorinated squaric acid cyanine near-infrared absorbing dye against other metal ions, N,N-dimethylformamide was used as a solvent to formulate the synthesized fluorinated squaric acid cyanine near-infrared absorbing dye to a concentration of approximately 0.5 (concentration 3.6 × 10⁻⁶) with a maximum absorbance in the near-infrared region. -5 After measuring the absorption spectrum of a solution containing mol / L zinc acetate, 5 mg of zinc acetate dihydrate was added to 3.3 mL of the solution. After mixing thoroughly, the changes in the visible to near-infrared absorption spectrum were measured. Then, two groups of solutions containing different concentrations of other metal ions were added: ① 10 mg 5wt% potassium chloride aqueous solution + 10 mg 5wt% calcium chloride aqueous solution + 10 mg 5wt% N,N-dimethylformamide solution of manganese acetate tetrahydrate + 10 mg 5wt% N,N-dimethylformamide solution of cobalt acetate tetrahydrate + 10 mg 5wt% N,N-dimethylformamide solution of magnesium acetate tetrahydrate; ② 20 mg 5wt% potassium chloride aqueous solution + 20 mg 5wt% calcium chloride aqueous solution + 20 mg 5wt% N,N-dimethylformamide solution of manganese acetate tetrahydrate + 20 mg 5wt% N,N-dimethylformamide solution of cobalt acetate tetrahydrate + 20 mg 5wt% N,N-dimethylformamide solution of magnesium acetate tetrahydrate. After thorough mixing, the changes in its visible to near-infrared absorption spectrum were measured, and the results are as follows: Figure 4 As shown. By Figure 4 It can be seen that when other metal ions are added to the solution, no other near-infrared absorption peaks are generated in the figure. Furthermore, the addition of other metal ions has little effect on the near-infrared absorption generated by the addition of zinc ions to the fluorine-containing near-infrared absorber acid cyanine dye, proving that it has good anti-interference performance and can thus achieve effective identification of zinc ions.

[0040] Comparative example: Fluorine-free squaricine near-infrared absorbing dyes ( Preparation of ) 3.48 g of 1,8-diaminonaphthalene (98%, 22.0 mmol), 2.643 g of acetophenone (98%, 22.0 mmol), 103.9 mg of p-toluenesulfonic acid monohydrate (0.546 mmol), and 37 mL of toluene were stirred and mixed. The mixture was then heated to 110 °C under a nitrogen atmosphere and refluxed for 6 hours (water generated during the reaction was removed by azeotropic distillation). After the reaction was complete, the toluene was evaporated, and the resulting dark brown oily substance was purified by silica gel column chromatography using a PE / EA mixture (6:1, V / V) as the eluent. The desired product eluent was collected by thin-layer chromatography analysis, and after removing the solvent by rotary evaporation, it was dried under vacuum (60 °C) to obtain an orange-yellow solid, which was 2-phenyl-2-methyl-2,3-dihydropeptididine, with a yield of 5.32 g and a yield of 92.9%.

[0041] 4.100 g of the obtained 2-phenyl-2-methyl-2,3-dihydropiperidine (15.75 mmol), 0.855 g of squaric acid (7.5 mmol), 15 mL of n-butanol, and 45 mL of toluene were stirred and mixed, then heated to 105 °C under a nitrogen atmosphere and refluxed for 3 hours (water generated during the reaction was removed by azeotropic distillation). After the reaction was complete, most of the solvent was evaporated under a nitrogen atmosphere, and then a small amount of ethyl acetate was added to the resulting reaction mixture with stirring, forming a blackish-brown-green precipitate. The resulting blackish-brown-green precipitate was collected by suction filtration, washed with a small amount of ethyl acetate, and dried under vacuum (60 °C) to obtain a blackish-brown-green solid product with a yield of 3.43 g, representing a yield of 76.4%.

[0042] The obtained dye compounds were analyzed by infrared absorption spectroscopy (reflectance method). 1 Identification was performed using spectroscopic methods including 1H-NMR (DMSO-d6), MALDI-TOF-MS, and visible to near-infrared absorption spectroscopy. The identification data are shown below: Infrared absorption spectroscopy (reflectance method): v max= 3736, 3397(NH), 3042(=CH), 2979, 2932,2863(CH3), 2358, 2341, 2329, 2115, 1606, 1556, 1539, 1516(C=C ring), 1491, 1448,1418, 1358 (CH3), 1306, 1275, 1206(CN), 1161, 1107(CO - ), 1030, 997, 945,897, 857, 812, 774, 745, 703, 670, 622 cm -1 .

[0043] 1 H-NMR spectrum (DMSO-d6): δ =11.32(br s, 2H, NH); 8.38(br s, 2H, NH); 7.97, 7.95, 7.85, 7.83(m, 3H, H arom ); 7.60, 7.58 (m, 4H, H) arom ); 7.37, 7.35, 7.33, 7.25, 7.23, 7.18, 7.17(m, 9H, H arom ); 6.82, 6.80, 6.72, 6.70(m, 4H, H arom ); 1.91(m, 6H, 2×CH3)ppm.

[0044] Mass spectrometry (MALDI-TOF-MS): m / z = 598.243 (M + (100%), calculated molecular weight: 598.237.

[0045] Visible to near-infrared absorption spectra: such as Figure 5 , its λ max =813 nm, ε max =1.5×10 5 M -1 cm -1 .

[0046] To test the recognition performance of the prepared fluorine-free squaric acid cyanine near-infrared absorbing dye for zinc ions, N,N-dimethylformamide was used as a solvent to formulate the synthesized fluorine-free squaric acid cyanine near-infrared absorbing dye to a concentration of approximately 0.5 (concentration 4.8 × 10⁻⁶) in the near-infrared region. -6After measuring the absorption spectrum of a solution containing mol / L zinc acetate, 5 mg, 10 mg, 15 mg, 30 mg, 45 mg, and 60 mg of zinc acetate dihydrate were added to 3.3 mL of this solution, respectively. After thorough mixing, the changes in the visible to near-infrared absorption spectra were measured sequentially. The results are as follows: Figure 6 As shown. By Figure 6 It can be seen that when different concentrations of zinc ions are added to the N,N-dimethylformamide solution of fluorine-free squaric acid cyanine near-infrared absorbing dye, there is no significant change in the maximum absorbance at 822 nm, indicating that this chemical is difficult to effectively identify zinc ions.

[0047] To compare the recognition performance of the prepared fluorinated squaric acid cyanine near-infrared absorbing dye and the fluorine-free squaric acid cyanine near-infrared absorbing dye for low concentrations of zinc ions, N,N-dimethylformamide was used as a solvent to prepare the fluorinated squaric acid cyanine near-infrared absorbing dye synthesized in the examples and the squaric acid cyanine near-infrared absorbing dye synthesized in the comparative examples to a maximum absorbance of approximately 0.5 in the near-infrared region (concentrations of 3.6 × 10⁻⁶ and 3.6 × 10⁻⁶, respectively). -5 mol / L, 4.8×10 -6 After measuring the absorption spectrum of a solution containing 1 mol / L zinc acetate, 0.5 mg, 1.0 mg, 1.5 mg, and 3.0 mg of zinc acetate dihydrate were added to 3.3 mL of the solution, respectively. After thorough mixing, the changes in the visible to near-infrared absorption spectra were measured sequentially, and the maximum absorbance at 805 nm and 822 nm were normalized and plotted. The results are shown below. Figure 7 As shown. By Figure 7 It can be seen that, compared with fluorine-free squaric acid cyanine near-infrared absorbing dyes, the addition of a low concentration of zinc ions to the N,N-dimethylformamide solution of fluorine-containing squaric acid cyanine near-infrared absorbing dye still significantly increases its maximum absorbance at 805 nm, indicating that it also has good recognition performance for low concentrations of zinc ions.

[0048] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A fluorine-containing squarylium near-infrared absorbing dye, characterized by: The chemical structural formula is: 。 2. A process for the preparation of a fluorine-containing squarylium near infrared absorbing dye according to claim 1, characterized in that: The method comprises the following steps: 1) Preparation of an intermediate product: 1,8-diaminonaphthalene, an acid catalyst, 2,2,2-trifluoroacetophenone and a dehydration solvent are mixed at room temperature, and azeotropic dehydration reaction is carried out under nitrogen protection; after the reaction is completed, the reaction liquid is cooled to room temperature, concentrated and purified to obtain the intermediate product 2-phenyl-2-trifluoromethyl-2,3-dihydrophthalene; 2) Preparation of a fluorine-containing near-infrared absorbing dye: 2-phenyl-2-trifluoromethyl-2,3-dihydrophthalene obtained in step 1) and squaric acid are mixed in a solvent at room temperature, and azeotropic dehydration reaction is carried out under nitrogen protection; after the reaction is completed, the reaction liquid is cooled to room temperature, the solid product is obtained by filtration, and the obtained solid product is washed with ethyl acetate to obtain the fluorine-containing near-infrared absorbing dye.

3. The method for preparing the fluorinated squaric acid cyanine near-infrared absorbing dye according to claim 2, characterized in that: The molar ratio of 1,8-diaminonaphthalene, the acid catalyst and 2,2,2-trifluoroacetophenone used in step 1) is 1:(0.01-0.1):

1.

4. The method for preparing the fluorinated squaric acid cyanine near-infrared absorbing dye according to claim 2, characterized in that: The acid catalyst in step 1) is any one of p-toluenesulfonic acid monohydrate, benzenesulfonic acid monohydrate, 4-chlorobenzenesulfonic acid, pyridine-3-sulfonic acid, ethanesulfonic acid, sulfuric acid, nitric acid and acetic acid.

5. The method for preparing the fluorinated squaric acid cyanine near-infrared absorbing dye according to claim 2, characterized in that: The dehydration solvent in step 1) is any one of aromatic hydrocarbons or cycloalkanes.

6. The method for preparing the fluorinated squaric acid cyanine near-infrared absorbing dye according to claim 2, characterized in that: The temperature of the azeotropic dehydration reaction in step 1) is 80-160 ℃, and the time is 5-15 h.

7. The method for preparing the fluorinated squaric acid cyanine near-infrared absorbing dye according to claim 2, characterized in that: The molar ratio of 2-phenyl-2-trifluoromethyl-2,3-dihydrophthalene and squaric acid used in step 2) is 2:1-2.5:

1.

8. The method for preparing the fluorinated squaric acid cyanine near-infrared absorbing dye according to claim 2, characterized in that: The solvent in step 2) is an alcohol or a mixture of an alcohol and any one of aromatic hydrocarbons, cycloalkanes, ethers, halogenated hydrocarbons and amides.

9. The method for preparing the fluorinated squaric acid cyanine near-infrared absorbing dye according to claim 2, characterized in that: The temperature of the azeotropic dehydration reaction in step 2) is 100-160 ℃, and the time is 3-6 h.

10. Use of the fluorine-containing squaraine near-infrared absorbing dye according to claim 1 in detection of zinc ions.

Images