A proton and fluoride ion dual-responsive organic fluorescent material and its preparation method

Abstract

The invention discloses a proton and fluoride dual-responsive organic fluorescent material and a preparation method thereof. The invention first uses 3,6-di-tert-butylcarbazole and N-bromosuccinimide as raw materials to prepare 1,8-dibromo-3,6-di-tert-butylcarbazole as an intermediate product, and then performs a Suzuki coupling reaction on the obtained intermediate product with 4-fluorophenylboric acid to generate 1,8-dibromo-3,6-di-tert-butyl (4-fluorophenyl)-9H carbazole having an A-D-A type molecular structure. The obtained organic fluorescent material can realize fluorescence quenching recognition response and qualitative and quantitative detection of protons and fluoride ions, and its preparation method is simple and the preparation process is simple.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic fluorescent material preparation, and in particular relates to a proton and fluoride ion dual-responsive organic fluorescent material and a preparation method thereof. Background Art

[0002] Existing organic fluorescent materials with stimulus-responsive behavior often only exhibit stimulus-responsive behavior to monovalent ions (cations or anions). To achieve multi-stimulus response, it is often necessary to design molecules with complex structures combined with complex stimulus-responsive mechanisms. This has disadvantages such as high preparation costs and complex technical routes. Summary of the Invention

[0003] The purpose of the present invention is to provide a proton and fluoride ion dual-responsive organic fluorescent material and a preparation method thereof. The organic fluorescent material has an ADA-type molecular structure, has richer recognition response behaviors, can realize fluorescence quenching recognition response and qualitative and quantitative detection of protons and fluoride ions, and has a simple preparation method and a simple preparation process.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A proton and fluoride ion dual-responsive organic fluorescent material, specifically 1,8-dibromo-3,6-di-tert-butyl (4-fluorophenyl)-9H carbazole, has the following chemical structure:

[0006] .

[0007] The preparation method of the proton and fluoride ion dual-responsive organic fluorescent material comprises the following steps:

[0008] 1) Preparation of 1,8-dibromo-3,6-di-tert-butylcarbazole: 3,6-di-tert-butylcarbazole and silica gel were added to dichloromethane at room temperature to prepare solution A; N-bromosuccinimide was dissolved in dichloromethane to prepare solution B; solution B was then slowly added to solution A for reaction in the dark. After the reaction, the product was filtered to remove the silica gel, and the silica gel was washed with a small amount of ethyl acetate. The washing solution and the product filtrate were combined, extracted and washed with saturated brine, and the organic layer was separated. After drying over anhydrous magnesium sulfate, filtration and concentration were performed, and separation was performed by silica gel column chromatography to obtain 1,8-dibromo-3,6-di-tert-butylcarbazole as an intermediate product.

[0009] 2) Preparation of 1,8-dibromo-3,6-di-tert-butyl(4-fluorophenyl)-9H-carbazole: 1,8-dibromo-3,6-di-tert-butylcarbazole (1.0 g, 2.8 mmol) obtained in step 1) was added to a mixture of toluene and water, mixed with 4-fluorophenylboric acid, tetrabutylammonium iodide, 2-dicyclohexylphosphine-2',6'-methoxydiphenyl, potassium carbonate, and bis(dibenzylideneacetone)palladium. The mixture was deoxygenated by nitrogen purging and then reacted under a nitrogen atmosphere. After completion of the reaction, the mixture was cooled to room temperature. The product was washed with saturated brine, extracted with ethyl acetate, dried over anhydrous magnesium sulfate, filtered, concentrated, and then separated by silica gel column chromatography to obtain the product.

[0010] Furthermore, in step 1), the molar ratio of 3,6-di-tert-butylcarbazole to N-bromosuccinimide is 1:2.1; and the mass ratio of 3,6-di-tert-butylcarbazole to silica gel is 1:0.4.

[0011] Furthermore, the temperature of the light-proof reaction in step 1) is 30° C. and the time is 4 hours.

[0012] Furthermore, the molar ratio of 1,8-dibromo-3,6-di-tert-butylcarbazole, 4-fluorophenylboric acid, tetrabutylammonium iodide, 2-dicyclohexylphosphine-2',6'-methoxydiphenyl, potassium carbonate, and bis(dibenzylideneacetone)palladium used in step 2) is 28:31:0.8:4.5:56:1.4.

[0013] Furthermore, the volume ratio of toluene to water in the mixed solution of toluene and water used in step 2) is 2:1.

[0014] Furthermore, the reaction temperature in step 2) is 100° C. and the reaction time is 48 h.

[0015] The significant advantages of the present invention are:

[0016] The organic fluorescent material provided by this invention has an ADA-type molecular structure, namely, carbazole as the electron-donating D unit and 4-fluorobenzene as the electron-withdrawing A unit. The carbazole NH position is exposed and unmodified, while the A unit is attached to the 1,8 position of the carbazole, resulting in less exposed space for the carbazole NH. Furthermore, the unmodified carbazole NH unit can serve as a recognition response site, enabling recognition of fluoride ions (based on the interaction between F and the H in NH) and recognition response of protons (protons mainly interact with the N in NH). This makes it suitable for fluorescence quenching recognition response and qualitative and quantitative detection of protons and fluoride ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart for preparing proton and fluoride ion dual-responsive organic fluorescent materials in the examples.

[0018] Figure 2Graphs showing the fluorescence spectra of the proton and fluoride ion dual-responsive organic fluorescent material prepared in the examples in different solvents.

[0019] Figure 3 These are fluorescence spectra obtained by adding different equivalents of trifluoroacetic acid to the proton and fluoride ion dual-responsive organic fluorescent material prepared in the example.

[0020] Figure 4 The fluorescence spectra obtained by adding different equivalents of tetrabutylammonium fluoride to the proton and fluoride ion dual-responsive organic fluorescent material prepared in the example. DETAILED DESCRIPTION

[0021] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto. Example

[0022] A proton and fluoride ion dual-responsive organic fluorescent material, the preparation process of which is as follows Figure 1 , the specific preparation steps are as follows:

[0023] 1) Preparation of 1,8-dibromo-3,6-di-tert-butylcarbazole (Compound C1): 3,6-di-tert-butylcarbazole (1.0 g, 3.6 mmol) and silica gel (0.4 g) were added to dichloromethane (35.00 mL) at room temperature to prepare solution A. N-bromosuccinimide (1.34 g, 7.5 mmol) was dissolved in dichloromethane (35.00 mL) to prepare solution B. Solution B was then slowly added to solution A and the reaction was carried out at 30°C in the dark for 4 h. h. After tracking the plate until the raw material is completely consumed, the product is filtered to remove silica gel, and the silica gel is washed with a small amount of ethyl acetate. The washing liquid is combined with the product filtrate, extracted and washed with saturated brine, and the organic layer is separated and dried over anhydrous magnesium sulfate. The organic layer is concentrated and separated by silica gel column chromatography using a mixed solution of petroleum ether and dichloromethane (10:1, v / v) as eluent to obtain 1.057 g of white powder of 1,8-dibromo-3,6-di-tert-butylcarbazole with a yield of 67.4%.

[0024] 2) Preparation of 1,8-dibromo-3,6-di-tert-butyl(4-fluorophenyl)-9H-carbazole (Compound C2): 1,8-dibromo-3,6-di-tert-butylcarbazole (1.0 g, 2.8 mmol), 4-fluorophenylboric acid (0.43 g, 3.1 mmol), tetrabutylammonium iodide (30 mg), 2-dicyclohexylphosphino-2',6'-methoxydiphenyl (183 mg, 0.45 mmol), potassium carbonate (0.77 mg, 5.6 mmol), and bis(dibenzylideneacetone)palladium (128 mg, 0.14 mmol) were sequentially added to a two-necked flask, and toluene (6 mL) and water (3 ml) were added. After nitrogen was added to deoxygenate, the mixture was reacted at 100°C under a nitrogen atmosphere for 48 hours. h, followed by tracking the plate until the raw material was completely consumed and then cooled to room temperature. The product was washed with saturated brine and extracted with ethyl acetate (repeated three times). The resulting organic layer was dried over anhydrous magnesium sulfate, filtered and concentrated. After concentration, it was separated by silica gel column chromatography using a mixed solution of petroleum ether and dichloromethane (10:1, v / v) as eluent to obtain 0.112 g of brown powder of 1,8-dibromo-3,6-di-tert-butyl(4-fluorophenyl)-9H-carbazole with a yield of 40%.

[0025] The NMR data of the obtained target compound are as follows:

[0026] δ H (400 MHz, Acetone- d 6) 8.08 (5 H, d, J 54.8), 7.53 (2 H, s), 7.20-6.91 (4 H, m), 6.41 (4 H, s), 6.03 (3 H, s), 1.46 (36 H, d, J 22.7); δ C (101 MHz,Acetone- d 6) 144.61, 143.85, 140.53, 136.07, 133.76, 130.03, 126.51, 124.75,124.59, 123.81, 122.50, 117.12, 116.52, 113.33, 113.12, 109.45,32.13, 32.00.

[0027] The H-C spectrum of the compound is consistent with its molecular structure, indicating that the compound was successfully prepared.

[0028] 1. Fluorescence spectroscopy: The target compound was added to toluene (TOL), ethyl acetate (EA), dimethylformamide (DMF), dichloromethane (DCM), and tetrahydrofuran (THF) respectively, and excited with 300 nm light. The results are shown in Figure 2 .

[0029] like Figure 2 As shown, in different solvents, the target compound produces single-peak emission in the short-wave range of deep blue light, and with the increase of solvent polarity, its emission peak produces a slight red shift, showing a solvation effect.

[0030] 2. Recognition and response to protons: The target compound was dispersed in tetrahydrofuran, and then different equivalents (0, 0.01, 0.03, 0.05, 0.1, 0.2, 0.3, 0.5, 1, 2, 5, 10, 20eq) of trifluoroacetic acid were added and excited with 300 nm light. The results are shown in Figure 3 .

[0031] like Figure 3 As shown in the figure, when a small amount of trifluoroacetic acid (<0.05eq) is added, the fluorescence intensity increases significantly and reaches a peak at 0.05eq. Then, with the continued addition of trifluoroacetic acid, the fluorescence intensity shows a linear quenching effect. This is because the N of carbazole contains unbonded electrons, which can interact with the proton acid, thereby exerting a recognition response effect.

[0032] 3. Recognition and response to fluoride ions: The target compound was dispersed in tetrahydrofuran, and then different equivalents (0, 0.01, 0.03, 0.05, 0.1, 0.2, 0.3, 0.5, 1, 2, 5, 10, 20eq) of tetrabutylammonium fluoride were added and excited with 300nm light. The results are shown in Fig. Figure 4 .

[0033] like Figure 4 As shown in the figure, when the addition amount of tetrabutylammonium fluoride is within the range of 0.2eq, its fluorescence intensity increases with the increase of the addition amount, and then further increases the fluoride ion content, and its fluorescence intensity shows a linear decrease phenomenon, so the quantitative detection of fluoride ions can be achieved in the range of 0.2~20eq.

[0034] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A proton and fluoride ion dual-responsive organic fluorescent material, characterized in that: The organic fluorescent material is 1,8-dibromo-3,6-di-tert-butyl (4-fluorophenyl)-9H carbazole, and its chemical structure is as follows: 。 2. A method for preparing a proton and fluoride ion dual-responsive organic fluorescent material according to claim 1, characterized in that: The following steps are involved: 1) Preparation of 1,8-dibromo-3,6-di-tert-butylcarbazole: 3,6-di-tert-butylcarbazole and silica gel were added to dichloromethane at room temperature to prepare solution A; N-bromosuccinimide was dissolved in dichloromethane to prepare solution B; solution B was then slowly added to solution A for reaction in the dark. After the reaction, the product was filtered to remove the silica gel, and the silica gel was washed with ethyl acetate. The washing solution and the product filtrate were combined, extracted and washed with saturated brine, and the organic layer was separated. After drying over anhydrous magnesium sulfate, filtration and concentration were performed, and separation was performed by silica gel column chromatography to obtain 1,8-dibromo-3,6-di-tert-butylcarbazole as an intermediate product. 2) Preparation of 1,8-dibromo-3,6-di-tert-butyl(4-fluorophenyl)-9H-carbazole: 1,8-dibromo-3,6-di-tert-butylcarbazole obtained in step 1) was added to a mixture of toluene and water with 4-fluorophenylboric acid, tetrabutylammonium iodide, 2-dicyclohexylphosphine-2',6'-methoxydiphenyl, potassium carbonate, and bis(dibenzylideneacetone)palladium, and the mixture was uniformly mixed. After nitrogen was added to deoxygenate the mixture, the mixture was reacted under a nitrogen atmosphere. After completion of the reaction, the mixture was cooled to room temperature. The product was washed with saturated brine, extracted with ethyl acetate, dried over anhydrous magnesium sulfate, filtered, concentrated, and then separated by silica gel column chromatography to obtain the product.

3. The method for preparing a proton and fluoride ion dual-responsive organic fluorescent material according to claim 2, characterized in that: The molar ratio of 3,6-di-tert-butylcarbazole to N-bromosuccinimide used in step 1) is 1:2.1; the mass ratio of 3,6-di-tert-butylcarbazole to silica gel used is 1:0.

4.

4. The method for preparing a proton and fluoride ion dual-responsive organic fluorescent material according to claim 2, characterized in that: The temperature of the light-proof reaction in step 1) is 30° C. and the reaction time is 4 h.

5. The method for preparing a proton and fluoride ion dual-responsive organic fluorescent material according to claim 2, characterized in that: The molar ratio of 1,8-dibromo-3,6-di-tert-butylcarbazole, 4-fluorophenylboric acid, tetrabutylammonium iodide, 2-dicyclohexylphosphine-2',6'-methoxydiphenyl, potassium carbonate, and bis(dibenzylideneacetone)palladium used in step 2) is 28:31:0.8:4.5:56:1.

4.

6. The method for preparing a proton and fluoride ion dual-responsive organic fluorescent material according to claim 2, characterized in that: The volume ratio of toluene to water in the mixed solution of toluene and water used in step 2) is 2:

1.

7. The method for preparing a proton and fluoride ion dual-responsive organic fluorescent material according to claim 2, characterized in that: The reaction temperature in step 2) is 100° C. and the reaction time is 48 h.

8. Use of the dual-responsive organic fluorescent material according to claim 1 in the quantitative detection of fluorine-containing organic compounds.

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