A fluorescence probe for detecting Pd 2+ and its preparation method and application

Abstract

The present invention belongs to the technical fields of organic synthesis and analytical chemistry, and particularly relates to a fluorescent probe for detecting Pd<supgt;2+< / supgt>, a preparation method thereof and an application. The chemical name of the fluorescent probe is: cyclo-(1R,2R)-1,2-cyclohexanediamide ethoxy-4-phenyl-(2-cyano)-vinyl-4-phenylmethylimino-phenyl-4-acetylcyclohexanediamine; the fluorescent probe uses cyanostilbene as a chromophore and has two (1R,2R)-1,2-cyclohexanediamine and Schiff base structures. The fluorescent probe can have a strong supramolecular interaction with Pd<supgt;2+< / supgt>, resulting in significant quenching of the fluorescence of the compound SDC. This characteristic can be used for the sensitive detection of Pd<supgt;2+< / supgt> in an aqueous environment, with little interference from other ions, and it is an ideal rapid and sensitive sensor for Pd<supgt;2+< / supgt>.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic synthesis and analytical chemistry, and specifically relates to a method for detecting Pd 2+ Fluorescent probe and its preparation method and application. Background Art

[0002] Palladium (Pd) is one of the important transition heavy metals and has been widely used in pharmaceutical research, organic catalysis, electrochemistry, aerospace and other fields. The widespread use of palladium may also lead to the 2+ Excessive residues in the environment, residual Pd 2+ It is easy to combine with some biological molecules and have adverse effects on human health. The World Health Organization has determined that Pd in drugs 2+ The maximum content of Pd in the diet per person per day is 5-10ppm. 2+ The intake of Pd does not exceed 1.5-15 μg. Therefore, the design can detect Pd in the environment and biological systems in real time and efficiently. 2+ The detection method is of great significance.

[0003] Currently used to detect Pd 2+ The main methods include inductively coupled plasma mass spectrometry, plasma emission spectrometry, atomic absorption spectrometry, solid phase microextraction-high performance liquid chromatography and fluorescence spectrometry. Among them, fluorescence spectrometry has become the most popular method for detecting Pd due to its advantages of short time consumption, fast response and simple process. 2+ The Chinese invention patent application with publication number CN110498794A discloses an imidazo[1,2-a]pyridine derivative Pd 2+ The fluorescent probe and its application, whose chemical name is 2-(2-(propargyloxy)phenyl)imidazo[1,2-a]pyridine, is a fluorescent probe for Pd in PBS solution (pH=7.40) 2+ It has unique fluorescence selectivity, high sensitivity and strong resistance to interference from other ions. However, as a traditional fluorescent material, this fluorescent probe is prone to fluorescence quenching when aggregated, which greatly limits the practical application of fluorescent probes. This fluorescent probe has poor luminescence performance and low quantum yield in poor solvents such as water phase, and is not suitable for real-time monitoring and analysis of food, environment and biological samples. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for detecting Pd with high sensitivity. 2+ Fluorescent probe and its preparation method and application.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for detecting Pd 2+The fluorescent probe, the chemical name of the fluorescent probe is: cyclo-(1R,2R)-1,2-cyclohexanediamide ethoxy-4-phenyl-(2-cyano)-vinyl-4-benzylideneamino-phenyl-4-acetylcyclohexanediamine; its chemical structural formula is shown in Formula (1):

[0006]

[0007] Another technical solution adopted by the present invention is: for preparing the above-mentioned fluorescent probe for detecting Pd 2+ The preparation method of the fluorescent probe, characterized in that, dissolving the compound of Formula (2) and the compound of Formula (3) in absolute ethanol, stirring and refluxing until the reaction is complete, then distilling off the solvent under reduced pressure to obtain a residue, and recrystallizing the residue to obtain the compound of Formula (1);

[0008]

[0009] Another technical solution adopted by the present invention is: as described above, the fluorescent probe for detecting Pd 2+ The application of the fluorescent probe in detecting Pd 2+ When detecting, mixing the tetrahydrofuran aqueous solution containing the compound of Formula (1) with a series of gradient concentration Pd 2+ Solutions, measuring the corresponding fluorescence intensity, and establishing a standard working curve with the fluorescence intensity as the ordinate and the Pd 2+ Concentration as the abscissa;

[0010] Mixing the tetrahydrofuran aqueous solution containing the compound of Formula (1) with the test solution, measuring the fluorescence intensity value after mixing, and reading out the Pd in the test solution according to the standard working curve 2+ Concentration.

[0011] The beneficial effect of the present invention is that: the fluorescent probe of the present invention uses cyanostilbene as the chromophore, with two (1R,2R)-1,2-cyclohexanediamine and Schiff base structures. This fluorescent probe can have a strong supramolecular interaction with Pd 2+ And cause significant quenching of the fluorescence of the compound SDC. This characteristic can be used for the sensitive detection of Pd in the water environment 2+ With little interference from other ions, it is an ideal Pd 2+ Rapid and sensitive sensor. Description of the Drawings

[0012] Figure 1 It is the infrared spectrum of the fluorescent probe in Example 1;

[0013] Figure 2 It is the nuclear magnetic resonance hydrogen spectrum of the fluorescent probe in Example 1;

[0014] Figure 3 It is the nuclear magnetic resonance carbon spectrum of the fluorescent probe in Example 1;

[0015] Figure 4 Mass spectrum of the fluorescent probe in Example 1;

[0016] Figure 5 For the fluorescent emission spectra of Pd at gradient concentrations in Example 5 2+ ;

[0017] Figure 6 Standard working curve in Example 5;

[0018] Figure 7 Fluorescent emission spectra of various metal ions in Example 6;

[0019] Figure 8 For the statistical chart of the interference degree of the sensitive detection of Pd by various metal ions 2+ . Detailed implementation mode

[0020] To illustrate the technical content, achieved objectives and effects of the present invention in detail, the following is described in conjunction with the implementation modes and accompanied by drawings.

[0021] A fluorescent probe for detecting Pd 2+ , the chemical name of the fluorescent probe is: cyclo-(1R,2R)-1,2-cyclohexanediamide ethoxy-4-phenyl-(2-cyano)-vinyl-4-benzylideneamino-phenyl-4-acetylcyclohexanediamine; its chemical structural formula is shown in Formula (1):

[0022]

[0023] As can be seen from the above description, the beneficial effects of the present invention are as follows: Cyano stilbene is a typical aggregation-induced emission molecule, and unique derivatives can be obtained through various functionalizations, and it shows specific recognition of specific guest ions, having good detection application prospects. The fluorescent probe of the present invention uses cyano stilbene as the chromophore, with two (1R,2R)-1,2-cyclohexanediamine and Schiff base structures. The Schiff base functional group and the oxygen-containing functional group have a coordination effect on Pd 2+ , and the cavity formed between the functional groups matches the size of Pd 2+ , so the fluorescent probe has good selectivity for Pd 2+ . The fluorescent probe can sensitively and selectively detect the presence of Pd 2+ through obvious fluorescence quenching. The presence of other guest ions has little or negligible interference on the detection of Pd 2+ , having good selective detection ability. This characteristic can be used to detect Pd 2+ in the water environment and is an ideal Pd 2+Fast and sensitive sensor has important practical application value for detecting samples containing Pd in actual complex environments. 2+

[0024] Another technical solution adopted in the present invention is: a preparation method of a fluorescent probe for detecting Pd 2+ , characterized in that the compound of formula (2) and the compound of formula (3) are dissolved in absolute ethanol, stirred and refluxed until the reaction is complete, then the solvent is distilled off under reduced pressure to obtain a residue, and the residue is recrystallized to obtain the compound of formula (1);

[0025]

[0026] As can be seen from the above description, the synthesis route of the compound of formula (1) is:

[0027]

[0028] Furthermore, the molar ratio of the compound of formula (2) to the compound of formula (3) is 0.5:1 to 1.5:1.

[0029] As can be seen from the above description, if the molar ratio of the compound of formula (2) to the compound of formula (3) is too high or too low, the yield of the product will be reduced and the separation difficulty of the product will be increased.

[0030] Furthermore, the reflux time is 12 to 36 h.

[0031] As can be seen from the above description, if the reflux time is short, the reaction is incomplete; if the reflux time is too long, the reaction energy consumption will be increased.

[0032] Furthermore, the residue is recrystallized with methanol and dichloromethane.

[0033] As can be seen from the above description, the solubility of the fluorescent probe of the present invention in methanol and dichloromethane changes greatly with temperature, and the recrystallization effect is good.

[0034] Furthermore, the preparation method of the compound of formula (2) is specifically: adding 1R,2R-di-acetylchloroamino-cyclohexane, 4-hydroxybenzaldehyde, potassium carbonate and potassium iodide into dry acetonitrile, stirring and refluxing until the reaction is complete, and obtaining the compound of formula (2) after separation and purification.

[0035] As can be seen from the above description, the synthesis route of the compound of formula (2) is as follows:

[0036]

[0037] ​Further, the preparation method of the compound of formula (3) is specifically as follows: The compound of formula (2), 4-nitrobenzyl cyanide and piperidine are added to dry dichloromethane and refluxed until the reaction is complete, and then the product is purified; after mixing and stirring the purified product and sodium sulfide nonahydrate, it is added to 1,4-dioxane and refluxed until the reaction is complete, and the compound of formula (3) is obtained after purification.

[0038] As can be seen from the above description, the synthetic route of the compound of formula (3) is as follows:

[0039]

[0040] Another technical solution adopted by the present invention is: the application of the fluorescence probe for detecting Pd 2+ when detecting Pd 2+ : An aqueous solution of tetrahydrofuran containing the compound of formula (1) is respectively mixed with a series of gradient concentration Pd 2+ solutions, and the corresponding fluorescence intensities are measured to establish a standard working curve with the fluorescence intensity as the ordinate and the Pd 2+ concentration as the abscissa;

[0041] An aqueous solution of tetrahydrofuran containing the compound of formula (1) is mixed with the test solution, and the fluorescence intensity value after mixing is measured, and the Pd 2+ concentration in the test solution is read according to the standard working curve.

[0042] As can be seen from the above description, first establish a standard working curve with the fluorescence intensity as the ordinate and the Pd 2+ concentration as the abscissa, and then read the Pd 2+ concentration in the test solution according to the standard working curve. This detection method is efficient, reasonable and highly specific.

[0043] Further, the volume ratio of tetrahydrofuran to water in the aqueous solution of tetrahydrofuran is 5:97 to 5:93.

[0044] Further, the detection wavelength during detection is 490 - 510 nm.

[0045] As can be seen from the above description, the fluorescence probe compound prepared by the present invention has strong blue-green fluorescence emission in a tetrahydrofuran-water (5:97 - 5:93) solution at a detection wavelength of 490 - 510 nm, and the detection effect is obvious and the sensitivity is high under this condition.

[0046] Example 1 of the present invention is: A fluorescence probe for detecting Pd 2+ with the molecular formula C 64 H 60N8O8, the chemical name is: cyclo-(1R,2R)-1,2-cyclohexanediamide ethoxy-4-phenyl-(2-cyano)-vinyl-4-benzylideneamino-phenyl-4-acetylcyclohexanediamine; its chemical structural formula is shown in Formula (1):

[0047]

[0048] The infrared spectrum of this fluorescent probe is shown in Figure 1 , infrared spectrum (KBr), v / cm -1 : 3000 - 3500 (NH), 2210 (-CN), 1597 (C=N); The nuclear magnetic resonance hydrogen spectrum is shown in Figure 2 , nuclear magnetic hydrogen spectrum (400 MHz, DMSO): δ ppm 7.84 - 7.87 (m, NH, 2H), 7.75 (s, 2H, N=CH), 7.72 (d, J = 8.0 Hz, 4H, ArH), 7.65 (d, J = 8.0 Hz, 4H, ArH), 7.52 (d, J = 8.0 Hz, 4H, ArH), 7.12 (d, J = 8.0 Hz, 4H, ArH), 6.82 - 6.92 (m, 12H, ArH), 4.41 (d, J = 16.0 Hz, 4H, OCH2), 3.81 (bs, 4H, OCH2), 3.55 - 3.64 (m, 4H, NCH2), 2.17 - 2.25 (m, 4H, CH2), 1.84 (bs, 4H, CH2), 1.34 - 1.45 (bs, 8H, CH2); The nuclear magnetic resonance carbon spectrum is shown in Figure 3 , nuclear magnetic carbon spectrum (101 MHz, DMSO) δ ppm: 191.62, 169.48, 167.68, 164.37, 162.94, 133.88, 132.00, 130.58, 128.01, 126.61, 125.54, 125.16, 118.62, 117.10, 115.30, 112.45, 104.74, 67.25, 52.65, 31.95, 24.78. The mass spectrum is shown in Figure 4 , high-resolution mass spectrum (m / s) (C 64 H 60 N8O8): Calcd for m / z = 1069.2100, found: [M + = 1069.2939, found: [M+Na + = 1092.4061, and the strong peak at 1069.2939 determines the structure of the fluorescent probe.

[0049] Example two of the present invention is: the preparation method of the fluorescent probe in Example one, characterized in that

[0050]

[0051]

[0052] S1: Synthesize the compound of formula (2), and the synthetic route is as follows:

[0053]

[0054] The specific synthesis method is as follows: Put 1R,2R - di - acetylchloroamino - cyclohexane (1.02 g, 3.81 mmol), 4 - hydroxybenzaldehyde (1.05 g, 8.21 mmol), potassium carbonate (1.3 g, 9.5 mmol) and potassium iodide (0.2 g, 1.2 mmol) in 50.00 mL of dry acetonitrile, stir and reflux for 24 hours for the reaction; After the reaction is completed, add 50.00 mL of 1 mol / L hydrochloric acid solution and 50.00 mL of dichloromethane to the mixture, and separate and concentrate the organic layer by rotary evaporation; Then use column chromatography (eluent: dichloromethane / ethyl acetate = 5 / 1, V / V) to purify the concentrated viscous compound to obtain the compound of formula (2) as a white solid, with a yield of 82%.

[0055] S2: Synthesize the compound of formula (3), and the synthetic route is as follows:

[0056]

[0057] The specific synthesis method is as follows: React a mixture containing the compound of formula (2) (2.01 g, 4.6 mmol), 4 - nitrobenzyl cyanide (2.03 g, 12.32 mmol) and piperidine (2.00 mL) in 50.00 mL of dry dichloromethane by refluxing for 12 hours, and monitor the reaction process by thin - layer chromatography technology; After the reaction is completed, separate the mixture with 30.00 mL of 1 mol / L hydrochloric acid solution and 50.00 mL of dichloromethane; The separated organic layer is concentrated and collected under reduced pressure, and then recrystallized with methanol to obtain a yellow solid; Mix and stir the yellow solid with sodium sulfide nonahydrate (2.04 g, 41.63 mmol), and reflux in 30.00 mL of 1,4 - dioxane for 18 h; After refluxing, treat the mixture with 50.00 mL of 1.0 mol / L hydrochloric acid solution, and adjust the pH of the mixture to 8 - 9 with saturated sodium bicarbonate solution; Then extract the mixture with 60.00 mL of dichloromethane, separate the organic phase under reduced pressure, and finally use column chromatography (eluent: dichloromethane / ethyl acetate = 1 / 3, V / V) to purify the organic phase. Obtain the compound of formula (3) as a yellow solid, with a yield of 78%.

[0058] S3: Dissolve 0.2 mmol of the compound of formula (2) and 0.2 mmol of the compound of formula (3) in 25 mL of absolute ethanol with a volume fraction of 99.5%, stir and reflux for 12 h. Monitoring by thin-layer chromatography shows that the compounds of formula (2) and formula (3) have been consumed completely; after the reaction is completed, distill off the solvent under reduced pressure to obtain a residue. The residue is recrystallized with 20 mL of methanol and 10 mL of dichloromethane to obtain the compound of formula (1) in the form of a yellow solid; the yield is 85%;

[0059] The synthetic route of the compound of formula (1) is as follows:

[0060]

[0061] Example 3 of the present invention is as follows:

[0062] The difference between Example 3 and Example 2 is only in S3: Dissolve 0.1 mmol of the compound of formula (2) and 0.2 mmol of the compound of formula (3) in 25 mL of absolute ethanol with a volume fraction of 99.9%, stir and reflux for 36 h. Monitoring by thin-layer chromatography shows that the compound of formula (2) has been consumed completely; after the reaction is completed, distill off the solvent under reduced pressure to obtain a residue. The residue is recrystallized with 30 mL of methanol and 10 mL of dichloromethane to obtain the compound of formula (1) in the form of a yellow solid; the yield is 45%.

[0063] Example 4 of the present invention is as follows:

[0064] The difference between Example 4 and Example 2 is only in S3: Dissolve 0.15 mmol of the compound of formula (2) and 0.1 mmol of the compound of formula (3) in 30 mL of absolute ethanol with a volume fraction of 99.5%, stir and reflux for 24 h. Monitoring by thin-layer chromatography shows that the compound of formula (3) has been consumed completely; after the reaction is completed, distill off the solvent under reduced pressure to obtain a residue. The residue is recrystallized with 25 mL of methanol and 10 mL of dichloromethane to obtain the compound of formula (1) in the form of a yellow solid; the yield is 46%.

[0065] Example 5 of the present invention is the application of the fluorescent probe of Example 1 in detecting Pd 2+ when, including the following steps:

[0066] S1: Mix the tetrahydrofuran aqueous solution (the volume ratio of tetrahydrofuran to water is 5:95) containing 1×10 -5 mol / L of the fluorescent probe with a series of gradient concentration Pd 2+ solutions respectively and measure the corresponding fluorescence intensities. The detection results are shown in Figure 5 , Figure 5 The curves from top to bottom in which the Pd 2+ concentration increases in turn, and the Pd 2+The concentrations are 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0 times that of the fluorescent probe, and the detection wavelength is 500 nm;

[0067] S2: Based on the detection results of S1, establish a standard working curve with fluorescence intensity as the ordinate and the concentration of Pd 2+ as the abscissa. This standard working curve is shown in Figure 6 ; It can be seen from Figure 5 and Figure 6 that there is a good linear relationship between the fluorescence intensity and the equivalent concentration of Pd 2+ in this detection method.

[0068] S3: Mix the tetrahydrofuran aqueous solution (the volume ratio of tetrahydrofuran to water is 5:95) containing 1×10 -5 mol / L of the fluorescent probe with the solution to be measured, measure the fluorescence intensity value of the mixture, and read the concentration of Pd 2+ in the solution to be measured according to the standard working curve.

[0069] Example six of the present invention is as follows: Add 1×10 -5 mol / L of the fluorescent probe in Example 1 to the tetrahydrofuran aqueous solution (the volume ratio of tetrahydrofuran to water is 5:95), and then add 1×10 -5 mol / L of various metal ions (blank, Li + , Na + , k + , Pd 2+ , Fe 3+ , Mg 2+ , Ca 2+ , Al 2+ , Cd 2+ , Co 2+ , Cu 2+ , Zn 2+ , Hg 2+ , Ni 2+ , Pd 2+ , Ag + , Cr 3+ , Mn 2+ , Sn 2+ ) for fluorescence detection. The detection results are shown in Figure 7 . It can be seen from Figure 7 that the fluorescent probe in Example 1 has good selective detection ability for Pd 2+ .

[0070] Example seven of the present invention is as follows: Add 1×10 -5 mol / L Pd to the tetrahydrofuran aqueous solution (the volume ratio of tetrahydrofuran to water is 5:95)2+ , 1×10 -5 mol / L of the fluorescent probe in Example 1, and then 1×10 -5 mol / L various metal ions (blank, Li + 、Na + , k + , Pd 2+ , Fe 3+ Mg 2+ , Ca 2+ 、Al 2+ 、Cd 2+ 、Co 2+ , Cu 2+ 、Zn 2+ , Hg 2+ 、Ni 2+ , Pd 2+ 、Ag + Cr 3+ , Mn 2+ Sn 2+ The detection results were summarized with those in Example 6, and the ratio of the maximum fluorescence intensity of the mixed solution (I) to the maximum fluorescence intensity of the solution with the same concentration containing only the fluorescent probe (I0) was used as the ordinate to plot the fluorescence intensity of other metal ions on Pd 2+ The statistical results of the sensitive detection interference degree are shown in Figure 8 , wherein SDS is the fluorescent probe in Example 1.

[0071] Depend on Figure 8 It can be seen that when other metal ions are added, the I / I0 ratio is close to 1, indicating that other guests have little effect on the fluorescence of the fluorescent probe. 2+ After that, the fluorescence was greatly weakened (I / I0 was around 0.15), which indicated that other ions 2+ The sensitive detection interference has little effect.

[0072] In summary, the fluorescent probe of the present invention uses cyanostilbene as a chromophore, has two (1R, 2R)-1,2-cyclohexanediamines and a Schiff base structure, and can selectively detect Pd through obvious fluorescence quenching. 2+ The presence of other guest ions has an effect on the 2+ The detection interference effect is very small or even negligible, and it has good selective detection ability. This feature can be used for Pd in water environment 2+ It is an ideal Pd 2+ Fast and sensitive sensor, for Pd-containing 2+ The sample detection has important practical application value.

[0073] The above are only embodiments of the present invention, and do not thus limit the patent scope of the present invention. All equivalent transformations made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in the relevant technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A fluorescence probe for detecting Pd 2+ , characterized in that The chemical name of the fluorescent probe is: cyclo-(1R,2R)-1,2-cyclohexanediamide ethoxy-4-phenyl-(2-cyano)-vinyl-4-benzylideneamino-phenyl-4-acetylcyclohexanediamine; Its chemical structural formula is shown in Formula (1):

2. A method for preparing a fluorescent probe for detecting Pd as described in claim 1 2+ , characterized in that Dissolve the compound of Formula (2) and the compound of Formula (3) in anhydrous alcohol, stir and reflux until the reaction is complete, then distill off the solvent under reduced pressure to obtain a residue, and recrystallize the residue to obtain the compound of Formula (1); 3. The preparation method of the fluorescent probe for detecting Pd 2+ , characterized in that The molar ratio of the compound of Formula (2) to the compound of Formula (3) is 0.5:1 to 1.5:

1.

4. The preparation method of the fluorescent probe for detecting Pd 2+ , characterized in that The reflux time is 12 to 36 hours.

5. The preparation method of the fluorescence probe for detecting Pd 2+ , characterized in that The preparation method of the compound of Formula (2) is specifically: add 1R,2R-di-acetylchloroamino-cyclohexane, 4-hydroxybenzaldehyde, potassium carbonate and potassium iodide to dry acetonitrile, stir and reflux until the reaction is complete, and obtain the compound of Formula (2) after separation and purification.

6. The preparation method of the fluorescent probe for detecting Pd 2+ , characterized in that The preparation method of the compound of Formula (3) is specifically: add the compound of Formula (2), 4-nitrobenzyl cyanide and piperidine to dry dichloromethane and reflux until the reaction is complete, and then purify the product; after mixing and stirring the purified product and sodium sulfide nonahydrate, add it to 1,4-dioxane and reflux until the reaction is complete, and obtain the compound of Formula (3) after purification.

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