A coumarin dye and its preparation method and application

Abstract

The present invention relates to a coumarin dye and its preparation method and application, and belongs to the field of organic dye synthesis technology. The most obvious feature of the dye is that a strong electron-donating amine group is introduced at its 7-position, and a strong electron-withdrawing cyano group is introduced at the 3,4-position to form a push-pull electron, with strong fluorescence activity. The dye is based on coumarin and has the advantages of high fluorescence quantum yield, good light resistance, large Stokes shift, adjustable optical properties, and a long emission wavelength. It has good application prospects in aspects such as fluorescence imaging. Moreover, the fluorescence behavior of the dye is greatly affected by organic solvents, especially for some common organic solvents with similar structures and properties. It has obvious distinguishing ability, and the dye can be used to prepare a solvochromic fluorescent probe with excellent performance.

Description

Technical Field

[0001] The invention belongs to the technical field of organic dye synthesis, and in particular relates to a coumarin dye and a preparation method and application thereof. Background Art

[0002] With the gradual development of biotechnology, fluorescent dyes are increasingly being used in fields such as bioanalysis and bioimaging. Currently, organic fluorescent probes used for biolabeling or derivatization primarily include coumarins, benzene and naphthalene derivatives, pyrenes, and benzo-pentacyclic compounds. Coumarin derivatives, in particular, hold a crucial position in biological research.

[0003] Coumarin-based fluorescent compounds, with benzopyrone as their parent ring structure, possess advantages such as high fluorescence quantum yield, excellent photostability, large Stokes shift, strong modifiability, and good biocompatibility. They are widely used as laser dyes, fluorescent brighteners, and fluorophores in small molecule fluorescent probes. Coumarin itself is not fluorescent, but it has a wide range of modifiable sites. By introducing groups of varying properties at different positions or by connecting various aromatic rings to expand the conjugated system, fluorescent dyes with diverse emission bands can be obtained.

[0004] Organic liquids, as an important energy source and physicochemical medium, are indispensable in industrial production and scientific research. Due to their frequent use, large-scale production is necessary. However, most organic liquids are toxic and hazardous, and difficult to degrade in nature. Therefore, they should be recycled and reused as much as possible after use, or be treated harmlessly. Therefore, it is crucial to accurately distinguish different types of organic liquids before recycling or treatment. In particular, distinguishing between organic solvents that are very similar in structure and properties has always been a challenging task. These solvents with similar physicochemical properties have a high degree of chemical structure similarity, and it is very difficult to distinguish them without the intervention of large-scale analytical instruments such as nuclear magnetic resonance and mass spectrometry.

[0005] Solvatochromism occurs when organic solvents interact with fluorescent molecules, causing the fluorescence spectrum to change color. In organic solvents of varying polarity, the absorption or emission spectra of fluorescent dye molecules exhibit distinct responses, exhibiting distinct differences in color development capabilities. Solvatochromic fluorescent dyes are now widely used in fluorescent probes, indicators, color developers, and molecular recognition.

[0006] Solvachromic fluorescent probes, whose absorption or fluorescence emission properties are highly sensitive to the structure and polarity of solvents, have attracted increasing scientific attention as sensors for distinguishing and detecting organic liquids or gases. Therefore, providing a new coumarin fluorescent dye as a sovachromic fluorescent probe is of great significance in this field. Summary of the Invention

[0007] The present invention aims to provide a coumarin dye, a preparation method and an application thereof. The coumarin fluorescent dye can be used to selectively and quickly distinguish three groups of common organic solvents with similar structures: (dichloromethane, chloroform and carbon tetrachloride), (ether, tetrahydrofuran and 1,4-dioxane) and (methanol, ethanol, n-propanol, n-butanol and n-pentanol).

[0008] To achieve the above object, the present invention provides a coumarin dye, the structural formula of which is as follows:

[0009]

[0010] The coumarin dye of the present invention is 3,4-dicyano-7-diethylaminocoumarin, which contains two cyano groups. The most notable feature of the coumarin dye of the present invention is the introduction of a strong electron-donating amino group at the 7-position and strong electron-withdrawing cyano groups at the 3- and 4-positions, forming an electron-pushing and electron-pulling mechanism. This produces a highly fluorescent compound with advantages such as high fluorescence quantum yield, good light resistance, a large Stokes shift, adjustable optical properties, and a long emission wavelength. It has good application prospects in fluorescence imaging and other fields. Furthermore, the fluorescence behavior of the coumarin dye is significantly affected by organic solvents, and it has a particularly strong ability to distinguish common organic solvents with similar structures and properties. Therefore, the coumarin dye can be used to prepare high-performance solvatochromic fluorescent probes.

[0011] A method for preparing the coumarin dye comprises the following steps:

[0012] Urea and choline chloride were mixed and heated to form a homogeneous liquid. After cooling, 4-diethylaminosalicylaldehyde and ethyl cyanoacetate were added and reacted at 80-100° C. for 1-2 hours. The reaction mixture was poured into water while hot and filtered. The solid was collected, washed, and filtered to obtain compound A. The structural formula of compound A is as follows:

[0013]

[0014] 1,8-diazobisspiro[5.4.0]undec-7-ene (DBU) and trimethylsilyl cyanide are added to a first solvent and stirred to form a first solution. Compound A is added to the first solvent to form a suspension. The suspension is added to the first solution and reacted at room temperature for 25-40 hours. A second solvent is added for extraction. The organic phases are combined, dried, and recrystallized to obtain compound B, which is the coumarin dye.

[0015]

[0016] Furthermore, after urea and choline chloride are mixed, they are heated at 100-120° C. for 15-30 minutes until the solid forms a homogeneous liquid.

[0017] Furthermore, during the preparation of compound A, the solvent used for washing is ethanol or ethyl acetate.

[0018] Further, DBU and trimethylsilyl cyanide are stirred and reacted at room temperature for 0.5-1 h.

[0019] Further, the first solvent is N,N-dimethylformamide (DMF), acetonitrile, tetrahydrofuran or dichloromethane;

[0020] The second solvent is ethyl acetate or dichloromethane.

[0021] Furthermore, the preparation method of the coumarin dye is as follows:

[0022]

[0023] Urea (6.246 g, 0.104 mol) and choline chloride (7.229 g, 0.052 mol) were added to a clean two-necked flask and heated at 100-120°C for 15-30 min until the solid formed a homogeneous liquid. After the flask was cooled to room temperature, 4-diethylaminosalicylaldehyde (2.010 g, 0.0104 mol) and ethyl cyanoacetate (1.1 mL, 0.0104 mol) were added and reacted at 80-100°C for 1-2 h. The reaction mixture was added to water (94 mL, 5.28 mol) while hot and filtered to collect the solid. The solid was washed with a solvent (anhydrous ethanol or ethyl acetate, 25 mL) and filtered to obtain compound A (3-cyano-7-diethylaminocoumarin). The structural formula of compound A is as follows:

[0024]

[0025] A first solvent (N, N-dimethylformamide) (7 mL) was added to a clean and dry single-necked flask, and DBU (1.142 g, 0.0075 mol) and trimethylsilyl cyanide (1.488 g, 0.015 mol) were added under stirring, and the mixture was stirred at room temperature for 0.5-1 h to form a first solution. Compound A (1.211 g, 0.005 mol) was added to the first solvent (8 mL) to form a suspension, and the suspension was then dripped dropwise into the first solution. The mixture was reacted at room temperature for 25-40 h. After the reaction was completed, the reaction was quenched with 2 mL of saturated ammonium chloride solution, and ethyl acetate (40 mL) and ultrapure water (20 mL) were added to the reaction system and extracted three times. The organic phase was washed with 20 mL of ultrapure water each time. The organic phases were combined and spin-dried, and the residue after spin-dried was recrystallized and filtered to obtain compound B, which is the coumarin dye.

[0026]

[0027] A solvatochromic fluorescent probe is prepared from the above-mentioned coumarin dye and can be used for visual detection of similar organic solvents.

[0028] The coumarin dye is used in the visual detection of similar organic solvents.

[0029] Furthermore, in the visual detection of the coumarin dye in a similar organic solvent, the ultraviolet absorption spectrum behavior of the coumarin dye is detected, comprising the following steps: placing the coumarin dye in a 25 mL volumetric flask, dissolving it with N,N-dimethylformamide and fixing the volume to prepare 3×10 -5 mol·L -1 The test solution is prepared and its ultraviolet absorption spectrum is detected; the fluorescence spectrum behavior of the coumarin dye in different solvents is detected, comprising the following steps: accurately weighing compound B, adding it to 1 mL of different solvents, respectively, to prepare a concentration of 1.0×10 -5 mol·L -1 The test solution is prepared and its fluorescence emission spectrum and fluorescence color change in different solvents are detected.

[0030] Furthermore, the similar organic solvents are methanol, ethanol, n-propanol, n-butanol and n-pentanol.

[0031] Furthermore, the similar organic solvents are diethyl ether, tetrahydrofuran (THF) and 1,4-dioxane.

[0032] Furthermore, the similar organic solvents are dichloromethane, chloroform and carbon tetrachloride.

[0033] Compared with the prior art, the present invention has the following advantages and technical effects:

[0034] The cyano group is a strong electron-withdrawing group, and its π orbital can overlap with the large π electrons of the aromatic ring, further broadening the π conjugated system, increasing the planar rigidity of the molecule, and enhancing the fluorescence performance. The diethylamino group is a strong electron-donating group. Introducing it into the 7-position of coumarin can improve the charge transfer ability within the coumarin molecule, thereby obtaining a fluorescent dye with high fluorescence quantum efficiency. The present invention introduces electron-withdrawing groups (cyano groups) at the 3-position and 4-position of coumarin, and simultaneously introduces an electron-donating group (diethylamino group) at the 7-position, so that the entire molecule forms a D-π-A conjugated pattern. The obtained coumarin dye has strong fluorescence and can selectively and quickly distinguish three groups of common organic solvents with similar structures: (methanol, ethanol, n-propanol, n-butanol, n-pentanol), (ether, tetrahydrofuran and 1,4-dioxane), and (dichloromethane, chloroform and carbon tetrachloride).

[0035] The coumarin dye synthesis method of the present invention is simple to operate and has mild reaction conditions. The coumarin dye prepared by the present invention realizes visual detection of various common organic liquids, especially for some common organic liquids with similar structural properties, it can achieve rapid differentiation and can be used as a very ideal solvatochromic fluorescent probe material. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0037] Figure 1 Schematic diagram of the preparation method of Example 1 of the present invention;

[0038] Figure 2 This is the nuclear magnetic resonance spectrum of the 3,4-dicyano-7-diethylaminocoumarin dye prepared in Example 1 of the present invention;

[0039] Figure 3 The ultraviolet absorption spectrum of the 3,4-dicyano-7-diethylaminocoumarin dye prepared in Example 1 of the present invention;

[0040] Figure 4 The fluorescence emission spectra of compound B prepared in Example 1 of the present invention in different alcohol solvents are shown;

[0041] Figure 5 The fluorescence emission spectra of compound B prepared in Example 1 of the present invention in different ether solvents are shown;

[0042] Figure 6 The fluorescence emission spectra of compound B prepared in Example 1 of the present invention in different chlorinated hydrocarbon solvents are shown in FIG.

[0043] Figure 7 This is a graph showing the fluorescence changes of compound B prepared in Example 1 of the present invention in different alcohol solvents;

[0044] Figure 8 This is a graph showing the fluorescence changes of compound B prepared in Example 1 of the present invention in different ether solvents;

[0045] Figure 9 This is a graph showing the fluorescence changes of compound B prepared in Example 1 of the present invention in different chlorinated hydrocarbon solvents. DETAILED DESCRIPTION

[0046] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0047] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0048] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0049] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0050] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0051] The room temperature in the embodiments of the present invention refers to 25±2°C.

[0052] Example 1

[0053] (1) Preparation of compound A (3-cyano-7-diethylaminocoumarin):

[0054]

[0055] Urea (6.246 g, 0.104 mol) and choline chloride (7.229 g, 0.052 mol) were added to a clean two-necked flask and heated until the solid formed a homogeneous liquid. After the flask cooled to room temperature, 4-diethylaminosalicylaldehyde (2.010 g, 0.0104 mol) and ethyl cyanoacetate (1.1 mL, 0.0104 mol) were added. The reaction was controlled at 100°C for 1 hour. While hot, the reaction mixture was added to water (94 mL, 5.28 mol) and stirred thoroughly. Filter and collect the solid into a flask. 25 mL of anhydrous ethanol was added to the flask, a reflux apparatus was set up, and the mixture was heated until the solid was loose in the liquid. After cooling, filter and collect the solid. Repeat the above steps twice to purify the solid to obtain compound A (1.706 g, 84.9% yield).

[0056] (2) Preparation of compound B (i.e., 3,4-dicyano-7-diethylaminocoumarin dye):

[0057]

[0058] To a clean and dry single-necked flask, add N,N-dimethylformamide (7 mL), and add 1,8-diazobisspiro[5.4.0]undec-7-ene (1.142 g, 0.0075 mol) and trimethylsilyl cyanide (1.488 g, 0.015 mol) with stirring. Stir at room temperature for 1 h to form a first solution. Add 3-cyano-7-diethylaminocoumarin (1.211 g, 0.005 mol) to N,N-dimethylformamide (8 mL) to form a suspension. Then, add the suspension dropwise into the first solution and react at room temperature for 40 h. After the reaction is completed, quench the reaction with 2 mL of saturated ammonium chloride solution. Then, 40 mL of ethyl acetate and 20 mL of ultrapure water were added to the reaction system, and the mixture was extracted three times. The organic phase was washed with 20 mL of ultrapure water each time. After the organic phases were combined, the mixture was dried by spin drying. The residue after spin drying was recrystallized and then filtered to obtain compound B (0.854 g, yield 64.0%). The nuclear magnetic resonance spectrum of the 3,4-dicyano-7-diethylaminocoumarin dye prepared in Example 1 is shown in FIG. Figure 2 , 1H NMR (600MHz, DMSO) δ7.54(d,J=9.2Hz,1H),7.01(dd,J=9.3,2.4Hz,1H),6.78(d,J=2.4Hz,1H),3.58(q,J=7.1Hz,1H),1.16(t,J=7.1Hz,1H).

[0059] Application Examples

[0060] The coumarin dye prepared in Example 1 was used for identification of similar organic solvents, and the steps were as follows:

[0061] The ultraviolet absorption spectrum behavior of compound B was detected:

[0062] Specific steps:

[0063] 1) The coumarin-based lyotropic fluorescent dye compound B prepared in Example 1 was placed in a 25 mL volumetric flask, dissolved in N,N-dimethylformamide and fixed to volume to prepare 3×10 -5 mol·L -1 The test solution was tested and its UV absorption spectrum was detected. The results are shown in Figure 3 .

[0064] Fluorescence emission spectra of compound B in different alcohol solvents:

[0065] Specific steps: accurately weigh the compound B prepared in Example 1, add it to 1 mL of different alcohol solvents, and prepare a concentration of 1.0×10 -5 mol·L -1 The alcohol solvents used are methanol, ethanol, propanol, butanol and pentanol. Using a fluorescence spectrometer, the maximum absorption wavelength is selected as the excitation wavelength, and the excitation wavelength is 510nm to obtain the fluorescence spectra of compound B in the above five alcohol solvents, as shown in FIG. Figure 4 The maximum fluorescence emission wavelengths of compound B in the five alcohol solvents were obtained, as shown in Table 1.

[0066] Table 1

[0067] Solvent name Maximum fluorescence emission wavelength (nm) Methanol 662 ethanol 579 Propanol 621 Butanol 580 Pentanol 571

[0068] The fluorescence emission spectra of compound B in different ether solvents are determined as follows:

[0069] Compound B prepared in Example 1 was added to 1 mL of different ether solvents to prepare a concentration of 1.0×10 -5 mol·L -1The solvents used were: diethyl ether, tetrahydrofuran and 1,4-dioxane. Using a fluorescence spectrometer, the maximum absorption wavelength was selected as the excitation wavelength, and the excitation wavelength was 510 nm to obtain the fluorescence spectra of compound B in these three solvents, as shown in FIG. Figure 5 The maximum fluorescence emission wavelengths of compound B in these three solvents are shown in Table 2.

[0070] Table 2

[0071] Solvent name Maximum fluorescence emission wavelength (nm) Ether 539 Tetrahydrofuran 508 1,4-Dioxane 547

[0072] The fluorescence emission spectra of compound B in different chlorinated hydrocarbon solvents are determined as follows:

[0073] Compound B prepared in Example 1 was added to 1 mL of different chlorinated hydrocarbon solvents to prepare a concentration of 1.0×10 -5 mol·L -1 The solvents used were dichloromethane, chloroform and carbon tetrachloride. The fluorescence spectra of compound B in these three solvents were obtained, as shown in FIG. Figure 6 The maximum fluorescence emission wavelengths of compound B in these three solvents are shown in Table 3.

[0074] Table 3

[0075] Solvent name Maximum fluorescence emission wavelength (nm) dichloromethane 562 Chloroform 553 Carbon tetrachloride 588

[0076] Determination of the fluorescence performance of compound B in different alcohol solvents: different alcohol solvents were used to prepare the -5 mol·L -1 The test solution, the solvents used are: methanol, ethanol, propanol, butanol and pentanol, shaken and allowed to stand for 5 minutes, under 365nm ultraviolet light irradiation, obtain the fluorescence luminescence change graph of compound B in these five different alcohol solvents, as shown in FIG. Figure 7 Methanol, ethanol, propanol, butanol and pentanol solutions emit green, purple, pink, yellow and blue fluorescence respectively, which are clearly different and easy to distinguish.

[0077] Determination of the fluorescence performance of compound B in different ether solvents: Different ether solvents were used to prepare the -5 mol·L -1 The test solution was shaken and allowed to stand for 5 minutes. The solvents used were: ether, tetrahydrofuran and 1,4-dioxane. Under 365nm ultraviolet light, the fluorescence luminescence change graph of compound B in these three different ether solvents was obtained, as shown in FIG. Figure 8 Ether, tetrahydrofuran, and 1,4-dioxane solutions emit blue, bright yellow, and light yellow fluorescence, respectively, with distinct differences and easy to distinguish.

[0078] Determination of the fluorescence performance of Compound B in different chlorinated hydrocarbon solvents: Different chlorinated hydrocarbon solvents were used, each shaken and allowed to stand for 5 minutes. The solvents used were: dichloromethane, chloroform, and carbon tetrachloride. Under 365nm ultraviolet light, the fluorescence change graphs of the coumarin-based solvatochromic fluorescent dye Compound B in these three different chlorinated hydrocarbon solvents were obtained, as shown in Figure 2. Figure 9 Dichloromethane, chloroform, and carbon tetrachloride solutions emit blue-purple, orange-yellow, and yellow-green fluorescence, respectively, with distinct differences and easy to distinguish.

[0079] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a coumarin dye, characterized in that: The following steps are involved: Urea and choline chloride were mixed and heated to form a homogeneous liquid. After cooling, 4-diethylaminosalicylaldehyde and ethyl cyanoacetate were added and reacted at 80-100° C. for 1-2 hours. The reaction mixture was poured into water while hot and filtered. The solid was collected, washed, and filtered to obtain compound A. The structural formula of compound A is as follows: 1,8-diazobisspiro[5.4.0]undec-7-ene and trimethylsilyl cyanide are added to a first solvent and stirred to form a first solution. Compound A is then added to the first solvent to form a suspension. The suspension is added to the first solution and reacted for 25-40 hours. A second solvent is added for extraction. The organic phases are combined, dried, and recrystallized to obtain compound B. Compound B is the coumarin dye. The structural formula of compound B is as follows:

2. The preparation method of coumarin dye according to claim 1, wherein After mixing urea and choline chloride, heat at 100-120°C for 15-30 minutes until the solid forms a homogeneous liquid.

3. The preparation method of coumarin dye according to claim 1, wherein 1,8-diazobisspiro[5.4.0]undec-7-ene and trimethylsilyl cyanide are stirred and reacted at room temperature for 0.5-1h.

4. The preparation method of coumarin dye according to claim 1, wherein The first solvent is N,N-dimethylformamide, acetonitrile, tetrahydrofuran or dichloromethane; The second solvent is ethyl acetate or dichloromethane.

5. Use of a coumarin dye prepared according to the preparation method according to any one of claims 1 to 4 in visual detection of similar organic solvents; The similar organic solvents are dichloromethane, chloroform and carbon tetrachloride; Alternatively, the similar organic solvent is diethyl ether, tetrahydrofuran and 1,4-dioxane; Alternatively, the similar organic solvent is methanol, ethanol, n-propanol, n-butanol and n-pentanol.

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