A D-A-π-A type organic dye, its preparation method and its application in sensing and detecting the water content of organic solvents

Abstract

The present invention discloses a preparation method of a D-A-π-A type organic small molecule dye and its application in sensing and detecting the water content of organic solvents. The organic small molecule has the following structure: The D-A-π-A type organic small molecule of the present invention has excellent ultraviolet absorption and fluorescence emission properties. The D-A-π-A type organic small molecule fluorescent probe can simply, reliably and highly sensitively detect the water content in organic solvents.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of functional materials, in particular to a preparation method of a D-A-π-A type organic dye and its application in sensing and detecting the water content of organic solvents. Background Art

[0002] Water is the most common impurity in organic solvents. It not only affects chemical reactions but also determines the reaction products. For example, in chemistry, especially in organometallic chemistry, the presence of water will lead to the quenching of reactive organometallic compounds, inhibiting reactions or reducing yields.

[0003] Traditional methods for detecting the water content in organic solvents include Karl Fischer titration, gas chromatography, liquid chromatography, and infrared spectroscopy analysis. These methods have limitations in terms of sensitivity, real-time performance, and the complexity of sample preparation. Therefore, in routine laboratory work such as organic synthesis, solvent purification, liquid chromatography, and industrial processes, there is a need for simple and efficient methods to detect the water content. However, fluorescence sensing analysis methods have received extensive attention due to their easy fabrication, high sensitivity and selectivity, low cost, short response time, and low detection limit. Fluorescent sensors based on photoinduced electron transfer (PET), intramolecular charge transfer (ICT), water-induced aggregation, reactive water sensing (chemical dosimeter), and hydrogen bonding have been widely reported. These sensors include small organic dyes, polymers, metal-organic framework materials (MOF), and covalent organic framework materials (COF). Currently, some typical fluorescent sensing dyes such as N-heteroaryl-1,8-naphthalimide, phenylene(poly)ethynyl dyes, triazaborine pyridine, and phenothiazine aldehyde have been applied to the detection of water in various solvents, but the development of new simple, inexpensive, and highly sensitive fluorescent dyes remains a challenging task.

[0004] Combining an electron-donating unit (D), a π-conjugated segment, and an electron-withdrawing unit (A) to form a donor-π-acceptor (D-π-A) configuration is an effective way to design organic fluorescent dyes. This push-pull chromophore exhibits a large Stokes shift (red shift) and a strong ICT effect from the donor unit to the acceptor unit. In addition, the optical properties of such molecules can be changed by altering the molecular polarity, viscosity, and hydrogen bonding, so they have potential application prospects in detecting water in organic solvents. However, there are still some problems with the unrestricted expansion of the π-conjugated system, such as: the absorption peak does not always undergo a red shift, the molecular π-π aggregation becomes more serious, and the photostability will deteriorate. Compared with D-π-A type molecules, introducing a set of electron-withdrawing conjugated components as additional electron acceptors in D-A-π-A type molecules not only helps to improve the energy level, absorption spectrum, and optoelectronic properties, but also greatly improves the photostability.

[0005] In existing research, D-A-π-A structured materials are widely used in organic solar cells (OSCs), organic light-emitting diodes (OLEDs), dye-sensitized solar cells (DSSCs), and perovskite solar cells (PSCs). However, there is little research on the application of D-A-π-A type molecules as fluorescent sensors. Therefore, developing such sensors for analyte detection has potential application prospects.

[0006] Through retrieval, no patent publication documents related to this invention patent application have been found. Summary of the Invention

[0007] The purpose of the present invention is to overcome the problems existing in the prior art and provide a D-A-π-A type organic dye, its preparation method, and its application in sensing and detecting the water content of organic solvents.

[0008] The technical solution adopted by the present invention to solve the technical problems is as follows:

[0009] The first aspect of the present invention provides a D-A-π-A type organic small molecule dye (LM-3), and the molecule has the structure shown in Formula I:

[0010]

[0011] The second aspect of the present invention provides a preparation method of the above D-A-π-A type organic small molecule dye (LM-3), and the method includes the following steps:

[0012] (1) Take 4,7-dibromo-2-(3,4,5-trifluorophenyl)-2H-benzotriazole, 4-borate-N,N-bis(4-methoxyphenyl)aniline, tetrakis(triphenylphosphine)palladium, and potassium carbonate and dissolve them in a mixed solution of toluene and water. Heat to 110 - 120 °C under an argon atmosphere and react for 10 - 15 hours. Extract with dichloromethane, dry the lower organic phase with anhydrous sodium sulfate, filter and concentrate, and then separate by silica gel chromatography column to obtain Intermediate 1. The reaction formula for this step is:

[0013]

[0014] (2) Take Intermediate 4-formylphenylboronic acid, potassium carbonate, and tetrakis(triphenylphosphine)palladium and dissolve them in a mixed solution of tetrahydrofuran and water. Heat to 70 - 80 °C under an argon atmosphere and react for 10 - 15 hours. Extract with dichloromethane, dry the lower organic phase with anhydrous sodium sulfate, filter and concentrate, and then separate by silica gel chromatography column to obtain 4-(7-(4-(bis(4-methoxyphenyl)amino)phenyl)-2-(3,4,5-trifluorophenyl)-2H-benzotriazol-4-yl)benzaldehyde (LM-3) red solid. The reaction formula for this step is:

[0015]

[0016] Further, in the step (1), the molar ratio of 4,7-dibromo-2-(3,4,5-trifluorophenyl)-2H-benzotriazole, 4-borate-N,N-bis(4-methoxyphenyl)aniline, potassium carbonate, and tetrakis(triphenylphosphine)palladium is 10:10:145:1.

[0017] Alternatively, in the step (1), the concentration of 4,7-dibromo-2-(3,4,5-trifluorophenyl)-2H-benzotriazole in the mixed solution is 0.02 - 0.025 mol / L;

[0018] Alternatively, in the step (2), the molar ratio of intermediate 4-formylphenylboronic acid pinacol ester, potassium carbonate, and tetrakis(triphenylphosphine)palladium is 4.4:8.8:144:1.

[0019] Alternatively, in the step (2), the concentration of intermediate 1 in the mixed solution is 0.0055 - 0.0065 mol / L;

[0020] The third aspect of the present invention is to provide the application of the above D-A-π-A type organic small molecule dye (LM-3) in the field of sensing detection. In particular, the application method for detecting the water content in organic solvents.

[0021] Accurately weigh the D-A-π-A type organic small molecule, prepare a solution with an ultra-dry organic solvent, add water with different contents, and observe the change in fluorescence intensity. The ultra-dry organic solvent is: tetrahydrofuran or dioxane.

[0022] Advantages and beneficial effects of the present invention:

[0023] The D-A-π-A type organic small molecule of the present invention can accurately and quantitatively detect trace water in organic solvents (tetrahydrofuran and 1,4-dioxane) through fluorescence weakening. The detection limit of tetrahydrofuran is 0.048% and that of 1,4-dioxane is 0.0043%. Description of the drawings

[0024] Figure 1 It is the nuclear magnetic resonance hydrogen spectrum of the D-A-π-A type organic small molecule (LM-3) of the present invention;

[0025] Figure 2 The infrared spectrum of the D-A-π-A type organic small molecule LM-3 of the present invention;

[0026] Figure 3 It is the diagram of the change in the fluorescence peak intensity of the D-A-π-A type organic small molecule LM-3 of the present invention with the increase in water content in tetrahydrofuran solvent;

[0027] Figure 4Standard curve of water content vs. fluorescence intensity of the D-A-π-A type organic small molecule LM-3 of the present invention in tetrahydrofuran solvent;

[0028] Figure 5 Graph showing the change in fluorescence peak intensity of the D-A-π-A type organic small molecule LM-3 of the present invention with increasing water content in 1,4-dioxane solvent;

[0029] Figure 6 Standard curve of water content vs. fluorescence intensity of the D-A-π-A type organic small molecule LM-3 of the present invention in 1,4-dioxane solvent. Detailed implementation manners

[0030] For a better understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments. However, the scope of protection required by the present invention is not limited to the scope represented by the embodiments.

[0031] The raw materials used in the present invention are all conventional commercially available products without special instructions. The methods used in the present invention are all conventional methods in the art without special instructions. The masses of various substances used in the present invention are all conventional masses used.

[0032] Example 1:

[0033] Weigh 4,7-dibromo-2-(3,4,5-trifluorophenyl)-2H-benzotriazole (405 mg, 1.00 mmol), 4-boronate-N,N-bis(4-methoxyphenyl)aniline (432 mg, 1.00 mmol), tetrakis(triphenylphosphine)palladium (115 mg, 0.1 mmol) and potassium carbonate (2.00 g, 14.5 mmol) and dissolve them in a mixture of toluene (40 mL) and water (5 mL). Heat the mixture to 115 °C under an argon atmosphere and react for 12 hours. Extract with dichloromethane. Dry the lower organic phase with anhydrous sodium sulfate, filter and concentrate, and then separate and purify by silica gel column chromatography (the eluent is dichloromethane:petroleum ether = 1:1) to obtain intermediate 1. 1 H NMR (400 MHz, CDCl3) δ 8.19 - 8.10 (m, 2H), 7.89 (d, J = 8.9 Hz, 2H), 7.67 (d, J = 7.7 Hz, 1H), 7.42 (d, J = 7.8 Hz, 1H), 7.15 (d, J = 8.9 Hz, 4H), 7.05 (d, J = 8.8 Hz, 2H), 6.88 (d, J = 9.0 Hz, 4H), 3.82 (s, 6H).

[0034] The reaction formula for this step is:

[0035]

[0036] Intermediate 1 (138 mg, 0.22 mmol), 4-formylphenylboronic acid pinacol ester (102 mg, 0.44 mmol), potassium carbonate (1.00 g, 7.25 mmol) and tetrakis(triphenylphosphine)palladium (58 mg, 0.05 mmol) were dissolved in a mixture of tetrahydrofuran (30 mL) and water (5 mL). The reaction was heated to 75 °C under an argon atmosphere for 12 hours. After the reaction, it was extracted with dichloromethane. The lower organic phase was dried over anhydrous sodium sulfate, filtered and concentrated, and then purified by silica gel column chromatography (eluent: petroleum ether:dichloromethane = 1:1) to obtain 4-(7-(4-(bis(4-methoxyphenyl)amino)phenyl)-2-(3,4,5-trifluorophenyl)-2H-benzotriazol-4-yl)benzaldehyde (LM-3) as a red solid. 1 H NMR (400 MHz, DMSO) δ 10.09 (s, 1H), 8.43 (d, J = 8.2 Hz, 2H), 8.38–8.30 (m, 2H), 8.13 (d, J = 8.8 Hz, 2H), 8.07 (d, J = 8.3 Hz, 2H), 7.96 (d, J = 7.6 Hz, 1H), 7.81 (d, J = 7.6 Hz, 1H), 7.14 (d, J = 8.8 Hz, 4H), 6.98 (d, J = 8.9 Hz, 4H), 6.89 (d, J = 8.8 Hz, 2H), 3.78 (s, 6H). The reaction equation for this step is:

[0037]

[0038] Figure 1 is the 1H NMR spectrum of LM-3, Figure 2 is the IR spectrum of LM-3. The absorption peak at 3435 cm -1 is for N-H stretching vibration, and the absorption peak at 1041 cm -1 corresponds to the bending vibration of the benzene ring ether bond.

[0039] The results of 1H NMR and IR characterizations indicate that the small molecule LM-3 was successfully synthesized in this invention.

[0040] Example 2: LM-3 was used for detecting the water content in tetrahydrofuran solvent.

[0041] LM-3 prepared in Example 1 was taken and formulated into 6×10 -3A tetrahydrofuran solution with a concentration of [[mol / L]]. Take 0.5 mL of the above-mentioned tetrahydrofuran solution, and add different volumes of water (0, 0.3, 0.5, 1, 3, 5, 7, 10, 15, 20, 30, 40, 50, 70 μL) respectively. Dilute to 1 mL with tetrahydrofuran, and then measure the fluorescence emission spectra of each solution using a fluorescence spectrophotometer. The excitation wavelength is 455 nm, and the emission wavelength is 625 nm. Record the maximum fluorescence emission intensity of each solution. The fluorescence spectrogram is as shown in Figure 3 shown. The fluorescence intensity of the LM-3 small molecule decreases with the increase of water content (v / v%), as shown in Figure 4 shown. There is a linear relationship between the water content and the fluorescence intensity, which can be used for the quantitative detection of trace water. The linear range is 0.3 - 2%, and the detection limit is 0.048%.

[0042] Example 3: Detection of water content in 1,4-dioxane solvent using LM-3.

[0043] Take the LM-3 prepared in Example 1 and prepare a 1,4-dioxane solution with a concentration of 6×10 -3 mol / L. Take 0.5 mL of the above-mentioned 1,4-dioxane solution, and add different volumes of water (0, 0.05, 0.3, 0.5, 1, 5, 7, 10, 15, 20, 30, 40, 50, 70 μL) respectively. Dilute to 1 mL with 1,4-dioxane, and then measure the fluorescence emission spectra of each solution using a fluorescence spectrophotometer. The excitation wavelength is 458 nm, and the emission wavelength is 584 nm. Record the maximum fluorescence emission intensity of each solution. The fluorescence spectrogram is as shown in Figure 5 , the fluorescence intensity of the LM-3 small molecule decreases with the increase of water content (v / v%), as shown in Figure 6 shown. There is a linear relationship between the water content and the fluorescence intensity, which can be used for the quantitative detection of trace water. The linear range is 0.3 - 1.5%, and the detection limit is 0.0043%.

[0044] From the above examples, it can be concluded that the detection limits of the quantitative detection method of the present invention for trace water content in organic solvents are: the detection limit of tetrahydrofuran is 0.048%, and the detection limit of 1,4-dioxane is 0.0043%. This shows that the fluorescence probe prepared by the present invention has high sensitivity to trace water in organic solvents. The quantitative detection method of the present invention has the advantages of convenience, high efficiency, high sensitivity and low detection limit, and can quantitatively determine trace water in organic solvents batch by batch and efficiently.

[0045] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art can understand that: various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the content disclosed in the embodiments.

Claims

1. A D-A-π-A type organic dye, characterized in that: It has the structure shown in Formula I:

2. The preparation method of the D-A-π-A type organic dye according to claim 1, wherein: It includes the following steps: (1) Dissolve 4,7-dibromo-2-(3,4,5-trifluorophenyl)-2H-benzotriazole, 4-borate-N,N-bis(4-methoxyphenyl)aniline, tetrakis(triphenylphosphine)palladium, and potassium carbonate in a mixed solution of toluene and water, heat to 110 - 120 °C under an argon atmosphere and react for 10 - 15 hours, extract with dichloromethane, dry the lower organic phase with anhydrous sodium sulfate, filter and concentrate, and then separate through a silica gel chromatography column to obtain Intermediate 1; (2) Dissolve Intermediate 1, 4-formylphenylboronic acid pinacol ester, potassium carbonate, and tetrakis(triphenylphosphine)palladium in a mixed solution of tetrahydrofuran and water, heat to 70 - 80 °C under an argon atmosphere and react for 10 - 15 hours, extract with dichloromethane, dry the lower organic phase with anhydrous sodium sulfate, filter and concentrate, and then separate through a silica gel chromatography column to obtain 4-(7-(4-(bis(4-methoxyphenyl)amino)phenyl)-2-(3,4,5-trifluorophenyl)-2H-benzotriazol-4-yl)benzaldehyde LM-3 red solid; 3. The preparation method according to claim 2, characterized in that: In step (1), the molar ratio of 4,7-dibromo-2-(3,4,5-trifluorophenyl)-2H-benzotriazole, 4-borate-N,N-bis(4-methoxyphenyl)aniline, potassium carbonate, and tetrakis(triphenylphosphine)palladium is 10:10:145:

1.

4. The preparation method according to claim 2, characterized in that: In step (1), the concentration of 4,7-dibromo-2-(3,4,5-trifluorophenyl)-2H-benzotriazole in the mixed solution is 0.02 - 0.025 mol / L.

5. The preparation method according to claim 2, wherein: In step (2), the concentration of Intermediate 1 in the mixed solution is 0.0055 - 0.0065 mol / L.

6. The application of the D-A-π-A type organic dye according to claim 1 in sensing and detecting the water content of organic solvents.

7. The application according to claim 6, wherein: The organic solvent is tetrahydrofuran or 1,4-dioxane.

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