An organic compound for detecting chromium ion content in solution and its application

Abstract

The present invention relates to the field of metal ion detection in solution, and in particular to an organic compound for detecting the content of chromium ions in solution and its application. The present invention proposes an organic compound using ethylenebenzopiperazine-pyridine-6-carboxylic acid as an ion complex and connected to a chromogenic group or a fluorescent group, which is a selective chromium ion complexing agent, which can be used for selective elimination and masking of chromium ions and has extremely high selectivity. By introducing a chromogenic group, it can be used for selective color development of chromium ions in various media, spectrophotometric determination, and preparation of color development test papers. By introducing a fluorescent group, it can also become a chromium ion fluorescent indicator, and the content of chromium ions in each solution can be calculated from its fluorescence intensity, which greatly improves efficiency, sensitivity and reproducibility.

Description

Technical Field

[0001] The invention relates to the technical field of metal ion detection in solution, and in particular to an organic compound for detecting the chromium ion content in solution and application thereof. Background Art

[0002] Chromium ion is the fourth toxic metal ion after mercury, lead and cadmium, and its toxicity has a huge impact on environmental water quality. Environmental protection departments in various countries have strict requirements for its wastewater discharge. However, unlike the first three ions, trivalent chromium ion is one of the necessary trace elements in the biological system, and its excessive or insufficient content has a very important impact on the biological system. Traditional detection methods include flame atomic absorption, inductively coupled atomic emission spectroscopy (ICP-AES), X-ray fluorescence spectroscopy and electrochemical analysis. These methods are very cumbersome for the detection of trace chromium ion content, and can only be carried out in the laboratory, and cannot be automatically detected. It is difficult to achieve full automation of water quality parameter detection and compensation measures. Fluorescence probe method is widely used in various fields due to its simple method and high sensitivity. At present, chromium ion fluorescent probes mainly use carboxyacridone, benzimidazole, dansylamide and piperazine as ion complexes. However, this series of fluorescent probes have poor selectivity for chromium ions, and the response range cannot meet the actual detection requirements. Moreover, those molecules do not contain functional groups that can be used for immobilization and cannot be used to make reversible sensors, so they cannot be applied to the continuous detection of chromium ions in various samples that need to be used multiple times.

[0003] In order to overcome the defects in the prior art, the present invention discloses an organic compound for detecting the chromium ion content in a solution and application thereof. Summary of the invention

[0004] In view of the problems existing in the background technology, an organic compound for detecting the content of chromium ions in a solution and its application are proposed. The present invention proposes an organic compound using ethylene benzopiperazine-pyridine-6-carboxylic acid as an ion complex and connected to a chromogenic group or a fluorescent group, which is a selective chromium ion complexing agent, which can be used for selective elimination and masking of chromium ions and has extremely high selectivity. By introducing a chromogenic group, it can be used for selective color development of chromium ions in various media, spectrophotometric determination, and preparation of color development test papers. By introducing a fluorescent group, it can also become a chromium ion fluorescent indicator, and the content of chromium ions in each solution can be calculated from its fluorescence intensity, which greatly improves efficiency, sensitivity and reproducibility.

[0005] The present invention provides an organic compound for detecting the chromium ion content in a solution. The organic compound uses ethylenebenzopiperazine-pyridine-6-carboxylic acid as an ion complex and is connected to a chromogenic group or a fluorescent group, and has the following structural formula:

[0006]

[0007] Preferably, the above organic compound includes at least one chromogenic group or one fluorescent group; the chromogenic group or the fluorescent group is selected from:

[0008]

[0009]

[0010] Preferably, R 5’ , R6, R7, R8, R 8’ , R9, R 10 , R 11 , R 11’ , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , R 19 , R 20 independently selected from -H, -OH, C1-C6 straight chain or branched alkyl, C1-C6 straight chain or branched alkoxy, C3-C6 cycloalkyl, -F, -Cl, -Br, -I, -CN, -NO2, -NH2,

[0011]

[0012] Preferably, R1, R2, R3 and R4 are selected from -H, C1-C6 straight chain or branched chain alkyl and C1-C6 straight chain or branched chain alkoxy, respectively.

[0013] Preferably, S and T are selected from the following groups: -H, C1-C6 straight chain or branched alkyl, -R 21 COOR 22 , -R 23 COR 24 , -R 25 OR 26 COOR 27 , -R 28 CONHR 29 、-OCOR 30 ,

[0014] Preferably, S and Y are selected from fluorescent or chromogenic groups, -H, -NO2, C1-C6 straight chain or branched chain alkyl.

[0015] Preferably, R21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 , R 28 , R 29 , R 30 , R 31 R is selected from -H, C1-C6 straight chain or branched alkyl; 32 , R 33 , R 34 They are respectively selected from -H, C1-C6 straight chain or branched alkyl, C1-C6 straight chain or branched alkoxy, and -COOH.

[0016] Preferably, S and T are selected from:

[0017]

[0018] Preferably, S and T are selected from -H, -CH3 and C2H5OCOCH2-, 2-methylpyridine-6-carboxylic acid, respectively.

[0019] Preferably, Y is selected from the group consisting of fluorescent groups:

[0020]

[0021] The present invention further proposes a product for detecting the metal ion content in a water environment, comprising the above-mentioned organic compound; the product is prepared into a semi-finished product by preparing the organic compound and a hydrophilic polymer as a carrier, and then the semi-finished product is added to a hydrogel for coating.

[0022] The present invention further proposes an application of an organic compound for detecting the chromium ion content in a solution, comprising the above-mentioned product, wherein the metal ion used for detection is Ca 2+ 、Cd 2+ 、Co 2+ Cr 3+ , Cu 2+ , Fe 2+ , Fe 3+ 、Ag + , Hg 2+ Mg 2+ , Mn 2+ 、Ni 2+ , Pb 2+ , Sr 2+ ,La 3+ 、Eu 3+ and Er 3+ .

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] 1. The present invention proposes an organic compound using ethylenebenzopiperazine-pyridine-6-carboxylic acid as an ion complex and connected to a chromogenic group or a fluorescent group, which is a selective chromium ion complexing agent, can be used for selective elimination and masking of chromium ions, and has extremely high selectivity. By introducing a chromogenic group, it can be used for selective color development of chromium ions in various media, spectrophotometric determination, and preparation of color development test papers. By introducing a fluorescent group, it can also become a chromium ion fluorescent indicator, and the content of chromium ions in each solution can be calculated from its fluorescence intensity, which greatly improves efficiency, sensitivity and reproducibility.

[0025] 2. The organic compound in the present invention is fixed on the surface of a hydrophilic polymer to produce a product, thereby achieving real-time monitoring of trace metal ion content, automating the entire analysis process, and greatly improving efficiency.

[0026] 3. The synthetic process route and process parameters involved in the present invention have mild and safe reaction conditions, and the product purity can reach more than 99.0%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the reaction route of the chromium ion complexing group in the preparation of the present invention.

[0028] Figure 2 The chromium ion fluorescent indicator ( Figure 1 Fluorescence excitation and emission spectra of compound 11).

[0029] Figure 3 The chromium ion fluorescent indicator ( Figure 1 Fluorescence spectra of compound 11) at different chromium ion concentrations.

[0030] Figure 4 The chromium ion fluorescent indicator ( Figure 1 Calibration curve of compound 11) for chromium ion.

[0031] Figure 5 is the chromium ion complexing group ( Figure 1 UV-visible spectra of compound 8) at different chromium ion concentrations.

[0032] Figure 6 is the chromium ion complexing group ( Figure 1 UV-visible calibration curve of compound 8) at different chromium ion concentrations.

[0033] Figure 7 is the chromium ion complexing group ( Figure 1 Fluorescence response ratio of compound 11) at different ion concentrations. DETAILED DESCRIPTION

[0034] The present invention provides an organic compound for detecting the chromium ion content in a solution. The organic compound uses ethylene benzopiperazine-pyridine-6-carboxylic acid as an ion complex, is connected to a chromogenic group or a fluorescent group, and has the following structural formula:

[0035]

[0036] The following is a synthetic route of the metal ion carrier compound and the color or fluorescent indicator in the present invention, taking a specific compound as an example. It should be noted that the specific compounds are used here only for the purpose of easy understanding, and those skilled in the art can make necessary changes according to the synthetic routes of these specific compounds to prepare other ion carrier compounds and indicators that can be used in the present invention.

[0037] Figure 1 The invention shows a preferred molecular structure (also called chromium ion carrier) of the present invention, namely, ethylenebenzopiperazine pyridine-6-carboxylic acid as a chromium ion complexing agent. Compound (1) 2,6-pyridinedicarboxylic acid is used as a raw material, and reacts with methanol under the catalysis of concentrated sulfuric acid to form a dimethyl ester compound (2). Then, it is reduced with sodium borohydride to 2-hydroxymethylpyridine-6-carboxylic acid methyl ester compound (3), and then reacts with thionyl chloride to obtain compound (4). Compound (5) o-phenylenediamine is used as a raw material, and reacts with chloroacetic acid to form a ring-closed compound (6), and then the amide is reduced with lithium aluminum hydride to generate a benzopiperazine compound (7). Then, it is alkylated with compound (4) to obtain compound (8). Then, it reacts with DMF to form an aldehyde compound (9), and finally, it is condensed with 4-chlororesorcinol to form a dichlorofluorescein derivative compound (10), and then the dimethyl ester is hydrolyzed with alkali to obtain the final product compound (11).

[0038] Follow the steps below Figure 1 The described reaction process is used to prepare various compounds mentioned in the present invention, and specific examples are made:

[0039] Example 1

[0040] Synthesis of compound 2

[0041] Weigh compound 1 (167 g, 1 mol, 1 eq) into a 2000 mL three-necked flask, add methanol (2000 ml) and concentrated sulfuric acid (50 mL), heat to reflux, stir overnight and react for 16 h. The solution is clear, and thin layer chromatography TLC (DCM: MeOH = 5: 1) shows that the reaction is complete. Concentrate the reaction solution to 200 mL, cool and stir for 30 minutes, filter, wash the filter cake with a small amount of methanol and dry to obtain the product compound 2 (156 g, 80%). 1H NMR (CDCl3) δ = 3.90 (s, 6H), 8.60 (m, 1H). 8.90-8.95 (m, 2H).

[0042] Synthesis of compound 3

[0043] Weigh compound 2 (19.5 g, 0.1 mol, 1 eq) into a 500 mL three-necked flask, add 300 mL of anhydrous THF / MeOH (5:1 300 mL), cool to 0 degrees, add sodium borohydride (3.8 g, 0.1 mol) in batches, warm to room temperature after addition, and react for 4 hours. Thin layer chromatography TLC (PE:EA=3:1) shows that the reaction is complete. Add saturated ammonium chloride to quench, spin dry the solvent, extract with ethyl acetate (300 mL*3), combine the organic phases and use saturated brine (500 mL*1), dry the organic phase with anhydrous sodium sulfate and spin dry to obtain compound 3 (12 g, 72%) as an off-white solid. 1H NMR (CDCl3) δ = 3.80 (s, 3H), 5.15 (d, 2H), 6.70 (t, 1H), 8.10 (m, 1H), 8.35-8.40 (m, 2H).

[0044] Synthesis of compound 4

[0045] Weigh compound 3 (8.4 g, 50 mmol, 1 eq) into a 250 mL three-necked flask, add 100 mL of thionyl chloride, stir overnight at room temperature, and TLC (PE:EA=3:1) shows that the reaction is complete. Concentrate the reaction solution to obtain compound 4 (8.9 g, 100%), which is used directly in the next step. 1H NMR (CDCl3) δ=3.85 (s, 3H), 5.25 (d, 2H), 8.15 (m, 1H), 8.45-8.50 (m, 2H).

[0046] Synthesis of compound 6

[0047] Weigh compound 5 (10.8 g, 100 mmol) and dissolve it in dimethylformamide (DMF, 100 mL) in a 250 mL three-necked flask, add chloroacetic acid (11 g, 120 mmol) and potassium carbonate (25.6 g, 200 mmol), stir at room temperature overnight, and then heat to 100 degrees to react overnight. TLC (PE: EA = 1: 1) detected that the reaction was complete. Concentrate the reaction solution, add water (300 mL), extract with ethyl acetate (300 mL * 3), dry with anhydrous sodium sulfate, and spin dry the organic phase to obtain a crude product. Column chromatography gave compound 6 (11.5 g, 78%). 1HNMR (CDCl3) δ = 3.99 (s, 2H), 4.80 (br, 1H), 6.75 (m, 1H), 6.80 (m, 1H), 6.90 (m, 1H), 9.55 (br, 1H).

[0048] Synthesis of compound 7

[0049] Weigh compound 6 (7.4 g, 50 mmol) and dissolve it in anhydrous THF (150 mL) in a 250 mL three-necked flask. Add lithium aluminum hydride (3.8 g, 100 mmol) in batches at zero degrees, and heat to 80 degrees to react overnight. TLC (PE: EA = 3: 1) detected that the reaction was complete. Quench the reaction with 15% sodium hydroxide (4 mL) at zero degrees, filter, wash the filter cake twice with tetrahydrofuran, combine the organic phases and spin dry the solvent to obtain 5 g (75%) of the product. 1HNMR (CDCl3) δ = 3.25 (s, 4H), 6.55 (m, 2H), 6.65 (m, 2H), 7.55 (br, 2H).

[0050] Synthesis of compound 8

[0051] Weigh compound 7 (1.34 g, 10 mmol) and dissolve it in dimethylformamide (DMF, 50 mL) in a 250 mL three-necked flask, add compound 4 (4.1 g, 22 mmol) and potassium carbonate (4.16 g, 30 mmol), and heat to 80 degrees for 18 hours. TLC (PE: EA = 1: 1) detected that the reaction was complete. Add water (200 mL) to the reaction solution, extract with 100 ml of ethyl acetate three times, combine the organic phases, wash once with saturated brine, dry with anhydrous sodium sulfate, and concentrate the organic phase to obtain 6.7 g of crude product. Column chromatography (eluent: dichloromethane, DCM) gave 1.5 g (35%) of product. 1H NMR (CDCl3) δ = 3.45 (s, 4H), 3.65 (s, 6H), 4.95 (s, 4H), 6.35 (m, 2H), 6.49 (m, 2H), 7.85 (m, 2H), 8.10 (m, 2H), 8.25 (m, 2H).

[0052] Synthesis of compound 9

[0053] Weigh compound 8 (0.43 g, 1 mmol) and dissolve it in DMF (5 mL) in a 100 mL three-necked flask. Add phosphorus oxychloride (1 mL) under argon protection, and heat to 60 degrees to react overnight. After the reaction is complete, add 50 mL of water, extract three times with ethyl acetate (EA, 50 mL), mix the organic phase and wash three times with water, separate the liquids, dry the organic phase with anhydrous sodium sulfate and spin dry to obtain a crude product, which is purified by column chromatography to obtain 320 mg (70%) of the product. 1H NMR (CDCl3) δ = 3.47 (s, 4H), 3.68 (s, 6H), 4.90 (s, 4H), 6.38 (m, 2H), 6.53 (m, 2H), 7.80 (m, 2H), 8.15 (m, 2H), 8.35 (m, 2H). 9.80(s,1H).

[0054] Synthesis of compound 10

[0055] Weigh compound 9 (0.23 g, 0.5 mmol), resorcinol (0.22 g, 1 mmol) and dissolve in dichloromethane (15 mL) in a 50 mL three-necked flask, add p-methanesulfonic acid (0.1 mL, cat), and react at room temperature overnight. After TLC (petroleum ether: ethyl acetate, PE: EA = 1: 1) detected that the reaction was complete, add 3 ml of triethylamine and DDQ (680 mg, 3 mmol), stir at room temperature overnight, spin dry the organic phase, and separate on a preparative plate to obtain 1050 mg (16%) of compound. 1H NMR (CDCl3) δ = 3.50 (s, 4H), 3.70 (s, 6H), 4.90 (s, 4H), 6.42 (m, 2H), 6.28 ( m, 2H), 6.58 (m, 2H), 6.78 (m, 2H), 7.85 (m, 2H), 8.17 (m, 2H), 8.38 (m, 2H).

[0056] Synthesis of compound 11

[0057] Compound 10 (25 mg) was weighed and dissolved in methanol (2 mL) in a 50 mL three-necked flask, 15% sodium hydroxide solution (1 mL) was added, and the mixture was reacted at room temperature overnight. The reaction solution was directly used for testing.

[0058] Testing of Compound 11

[0059] Compound 5 solution (40 μl) was diluted with 10 ml HEPES buffer solution to prepare a 40 μM HEPES buffer solution with a pH of 7.4 for testing. The UV-visible absorption spectrum test results of the solution in response to chromium ions are shown in Figure 2 .

[0060] Figure 2 The fluorescence excitation and emission spectra of the chromium ion fluorescent indicator compound 11 are shown. The indicator concentration is 0.1 mM in a 10 mM TRIS-HCl buffer solution at pH 7.0. Like the parent compound, this compound retains almost all the optical properties of dichlorofluorescein, with a maximum excitation at 470 nm, which is very suitable for commercially available blue light-emitting diodes, and a maximum emission at 530 nm, which is suitable for blue light filters.

[0061] Figure 3 The chromium ion fluorescent indicator of the present invention ( Figure 1 Fluorescence emission spectra of compound 11 at different chromium ion concentrations. The indicator concentration was 0.1 mM, and the excitation wavelength was 470 nm in a 10 mM TRIS-HCl buffer solution at pH 7.0. The fluorescence intensity decreased with increasing chromium ion concentration, and the signal changed fastest in the 800-1200 micromolar chromium ion concentration range.

[0062] Figure 4The chromium ion fluorescent indicator of the present invention ( Figure 1 The fluorescence calibration curve of compound 11) at different chromium ion concentrations has a response in the range of 0-1600 micromolar chromium ion concentration, and the maximum slope is around 800 micromolar, which can be used for the determination of chromium ion concentration in environmental water samples.

[0063] Figure 5 The chromium ion head of the present invention ( Figure 1 The UV-visible absorption spectra of compound 8 in Figure 1 at different chromium ion concentrations. The ion head concentration is 0.1 millimolar in a 10 millimolar TRIS-HCl buffer solution with a pH of 7.0. As the cadmium ion concentration increases, the absorbance at the maximum absorption peak at 247 nanometers increases, while the absorbance at 320 nanometers decreases, and there is an isosbestic point near 300 nanometers. This set of data proves that the chromium ion head complexes with the chromium ion, affecting the distribution of the electron cloud of the ion head, thereby causing corresponding changes in the UV-visible absorption spectrum. The maximum absorbance change occurs in the 600 micromolar chromium ion concentration range.

[0064] Figure 6 The chromium ion head of the present invention ( Figure 1 The corresponding calibration curve formed by the UV-visible absorption spectrum of compound 8) at different chromium ion concentrations. The ion head concentration is 0.1 millimolar in a 10 millimolar TRIS-HCl buffer solution with a pH of 7.0. The absorbance at the maximum absorption peak at 247 nanometers is plotted against the chromium ion concentration, and the maximum signal change occurs in the 600 micromolar chromium ion concentration range.

[0065] Figure 7 The PET type chromium ion fluorescent indicator of the present invention ( Figure 1 Fluorescence emission spectra of compound 11 in different metal ion solutions (the metal ion measured is Ag + , Ca 2+ 、Cd 2+ 、Co 2+ Cr 3+ , Cu 2+ , Er 3+ 、Eu 3+ , Fe 2+ , Fe 3+ , Hg 2+ ,La 3 + Mg 2+ , Mn 2+ 、Na + 、Ni 2+ , Pb 2+ , Sr 2+ 、Zn 2+). The data showed that the fluorescence enhancement of the molecule to chromium ions was the most significant, followed by rare earth ions Er 3+ and Eu 3+ ions have a slight quenching effect on the indicator, and the fluorescence intensity of other ions remains almost unchanged. These data show that the indicator has good selectivity for chromium ions.

[0066] The above data show that by introducing various substituents into substituted ethylene benzopiperazine, a series of new ion carriers can be obtained, and these carriers can also be connected with different fluorescent groups to produce a series of new fluorescent sensors to meet various needs. A general technician with professional knowledge in this field can use the combination of different substituents to draw inferences and prepare a series of color developers and fluorescent indicators for metal ions, especially chromium ions.

[0067] As can be seen from Example 1, in the technical solution of the present invention, a chromogenic group is introduced into the structure of the substituted phenyl of the ion carrier ethylene benzopiperazine to generate a series of molecules that can produce color responses to metal ions, especially chromium ions. Such molecules can produce different colors in samples with different ion concentrations, which can be detected by a photometer or the naked eye. A fluorescent group is introduced into the ion carrier of the present invention to generate a series of molecules that can produce fluorescent responses to metal ions, especially chromium ions. Such molecules can produce fluorescence of different intensities in samples with different chromium ion concentrations, which can be detected by a fluorescence instrument. Therefore, the organic compound of the present invention includes at least one chromogenic group or one fluorescent group. When U is a chromogenic group or a fluorescent group, Y can be other groups; when Y is a fluorescent group or a chromogenic group, U can be other groups, or U and Y form a ring to form at least one fluorescent or chromogenic group, as long as at least one chromogenic group or one fluorescent group is ensured to exist in the compound.

[0068] Embodiment 2

[0069] The present invention provides a product for detecting the chromium ion content in a solution, wherein the product is prepared by the compound in Example 1 and a hydrophilic polymer as a carrier, and then adding a hydrogel for coating. Common hydrophilic polymers can be used in the present invention, and the preferred polymer is aminocellulose.

[0070] In a specific embodiment, the product is a fluorescent probe or a sensitive membrane.

[0071] In a specific embodiment, the product can be made into a detection kit.

[0072] In a specific embodiment, the detection is continuous detection.

[0073] Embodiment 3

[0074] The present invention provides an application of an organic compound for detecting the chromium ion content in a solution. The product can be used to detect the following metal ions: Ca 2+ 、Cd 2+ 、Co 2+ Cr 3+ , Cu 2+ , Fe 2+ , Fe 3+ 、Ag + , Hg 2+ Mg 2+ , Mn 2+ 、Ni 2+ , Pb 2+ , Sr 2+ ,La 3+ 、Eu 3+ , Er 3+ .

[0075] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. An organic compound for detecting the chromium ion content in a solution, It is characterized in that The organic compound uses ethylene benzopiperazine-pyridine-6-carboxylic acid as an ion complex, which is connected to a color-developing group or a fluorescent group, and has the following structural formula: ； In the above organic compounds, R 1 , R 2 , R 3 and R 4 All are selected from -H; U is selected from -H; Y is selected from a fluorescent group ; S and T are selected from ; Among them, R 12 and R 13 independently selected from -H, -OH, C1-C6 straight chain or branched alkyl, C1-C6 straight chain or branched alkoxy, C3-C6 cycloalkyl, -F, -Cl, -Br, -I, -CN, -NO 2 or -NH 2 .

2. The organic compound for detecting the chromium ion content in a solution according to claim 1, It is characterized in that The specific structural formula of the organic compound is: 。 3. A product for detecting the content of metal ions in water environment, It is characterized in that The product comprises the organic compound as claimed in claim 1; the product is prepared into a semi-finished product by using the organic compound and a hydrophilic polymer as a carrier, and then the semi-finished product is added into a hydrogel for coating.

4. An application of an organic compound for detecting the chromium ion content in a solution, It is characterized in that The organic compound according to claim 1 is used for detecting Cr in a solution. 3+ .

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