A polyacid-based complex for detecting phenolic compounds and trace phenol and application thereof

Abstract

A polyacid-based complex for detecting phenolic compounds and trace phenol and application thereof, the complex can be used as a catalyst for detecting trace phenolic compounds by aminoantipyrine colorimetry, and has a molecular formula as follows: {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O; wherein, dap is 1,2-propylenediamine; 3-HPA is 3-(3-pyridine) acrylic acid, and 3-PA is a carboxyl group of 3-(3-pyridine) acrylic acid with one proton removed. The polyacid-based complex for detecting phenolic compounds and trace phenol has an application in detecting phenolic compounds. The polyacid-based complex has the advantages of simple synthesis method, short synthesis period and high synthesis yield. The polyacid-based complex can be used to detect various phenolic compounds such as phenol, 4-chlorophenol, o-methylphenol, p-nitrophenol and phloroglucinol, and in particular, the polyacid-based complex can be used to detect trace phenol with low detection limit.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic pollutant detection and synthetic method, and particularly relates to a polyacid-based complex for detecting phenolic compounds and trace phenol and application thereof. BACKGROUND

[0002] Phenolic compounds refer to compounds generated by replacing hydrogen atoms on a benzene ring in aromatic hydrocarbons with hydroxyl groups, which exist widely in nature. Phenolic compounds in surface water mainly come from industrial wastewater such as oil refining, gas washing, coking, papermaking, synthetic ammonia, wood preservation and chemical industry. Since oxygen atoms exist in the structure of phenolic compounds, most of the phenolic compounds have quite high solubility in water, which enhances the migration and transformation ability of the phenolic compounds, so that the phenolic compounds become one of the main pollutants in industrial wastewater. Among the numerous phenolic compounds, phenol has a special odor of colorless needle-shaped crystals, is toxic, is an important raw material for producing certain resins, bactericides, preservatives and drugs (such as aspirin), and can also be used for disinfecting surgical instruments and excrement treatment, skin sterilization, itching and otitis media. At the same time, phenol is also the most toxic among the phenolic compounds, and the content of phenol is the highest in the wastewater containing phenol. Environmental monitoring often takes phenol as a pollution index. When the concentration of phenol in water is relatively low, it will cause dizziness, headache, loss of appetite, vomiting, diarrhea and other digestive symptoms. If the concentration is relatively high, it will penetrate into the internal tissues of the body, which can cause systemic poisoning, coma, respiratory failure, blindness and even death. Therefore, the content of phenol is regulated to be lower than 0.002 mg / L in the drinking water quality standard of China.

[0003] At present, the methods for detecting phenolic compounds include spectrophotometry, high performance liquid chromatography, liquid chromatography-tandem mass spectrometry, gas chromatography-mass spectrometry and nuclear magnetic resonance method. Among them, the aminoantipyrine colorimetric method is one of the most basic methods in spectrophotometry, which detects phenolic compounds by using the oxidative coupling reaction of phenolic compounds and colorless 4-aminoantipyrine (4-AAP) to generate colored quinonimine with the assistance of H2O2 and a catalyst. This method has low detection cost, simple operation, short time and high accuracy, so it has attracted widespread attention. Professor Pang Haijun of Harbin University of Science and Technology reported a polyacid-based complex [Co2(btap)4(H2O)4][SiW 12 O 40 ], which can detect phenol, but the detection limit is 1.32 μM, which cannot realize the detection of phenolic compounds and trace phenol. SUMMARY

[0004] The technical problem solved by the present application is to provide a polyacid-based complex for detecting phenolic compounds and trace phenol, and application thereof, which can detect various phenolic compounds such as phenol, 4-chlorophenol, o-methylphenol, p-nitrophenol and phloroglucinol, and in particular, can detect trace phenol with a low detection limit.

[0005] The technical solution of the present application is:

[0006] The present application provides a polyacid-based complex for detecting phenolic compounds and trace phenol, which can be used as a catalyst for detecting trace phenolic compounds by aminoantipyrine colorimetry, and has the following molecular formula:

[0007] {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O;

[0008] wherein, dap is 1,2-propanediamine; 3-HPA is 3-(3-pyridine) acrylic acid, and 3-PA is a carboxyl group of 3-(3-pyridine) acrylic acid from which one proton is removed.

[0009] Further, the complex can be used for detecting phenol, 4-chlorophenol, o-methylphenol, p-nitrophenol and phloroglucinol, wherein the detection limit of phenol is 0.36 μM, the detection limit of 4-chlorophenol is 1.89 μM, the detection limit of o-methylphenol is 2.12 μM, the detection limit of p-nitrophenol is 1.67 μM, and the detection limit of phloroglucinol is 5.02 μM; more preferably, the complex can be used for detecting trace phenol, and the detection limit of phenol is 0.36 μM.

[0010] Further, the specific synthesis steps of the complex are as follows:

[0011] (1) Cu(NO3)2·3H2O, 3-(3-pyridine) acrylic acid, H4[SiW 12 O 40 ]·xH2O, 1,4-naphthalene dicarboxylic acid and 1,2-propanediamine are added to an aqueous solution of acetonitrile, stirred at room temperature for 2 h to obtain a mixed solution; wherein,

[0012] the molar ratio of Cu(NO3)2·3H2O, 3-(3-pyridine) acrylic acid, 1,4-naphthalene dicarboxylic acid to H4[SiW 12 O 40 ]·xH2O is 12.2:1, 15.8:1 and 5.4:1 respectively, the molar volume ratio of H4[SiW 12 O 40 ]·xH2O to 1,2-propanediamine is 0.85 mol / L, and the volume ratio of 1,2-propanediamine to the aqueous solution of acetonitrile is 1:30.

[0013] (2) The mixed solution is added to a stainless steel autoclave with a polytetrafluoroethylene inner liner, heated to 120℃, and kept for 4 days, and then cooled to obtain blue block-shaped crystals, which are washed with an acetonitrile aqueous solution to obtain a polyoxometalate-based complex {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O.

[0014] The 1,4-naphthalene dicarboxylic acid ligand in the raw material is used to form a mixed ligand to construct the polyoxometalate-based complex, but the 1,4-naphthalene dicarboxylic acid ligand does not appear in the structure of the polyoxometalate-based complex; if the 1,4-naphthalene dicarboxylic acid ligand is removed during synthesis, the polyoxometalate-based complex cannot be obtained.

[0015] Further, in step (2), the heating and cooling rates are both 10℃ / h.

[0016] Further, in steps (1) and (2), the volume ratio of acetonitrile to water in the acetonitrile aqueous solution is 1:2.

[0017] Further, the washing times with the acetonitrile aqueous solution are 3 times.

[0018] The polyoxometalate-based complex for detecting phenolic compounds and trace phenol described above is applied to detecting phenolic compounds.

[0019] The application of a polyoxometalate-based complex for detecting trace phenolic compounds to detecting phenolic compounds, the steps for detecting phenolic compounds and trace phenol are as follows:

[0020] (1) The polyoxometalate-based complex {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O is ground to obtain a polyoxometalate-based complex powder;

[0021] (2) The polyoxometalate-based complex powder and 4-aminoantipyrine are dispersed in 3mL of water to prepare a suspension with a concentration of 0.1mg·mL -1 of the polyoxometalate-based complex powder and 1.5mg·mL -1 of 4-aminoantipyrine, the pH of the solution is adjusted to 3 with 1M hydrochloric acid, and ultrasonic dispersion is performed for 5min at room temperature to obtain a suspension;

[0022] (3) Add the sample to be detected into the suspension obtained in step (2), then add H2O2 to make the concentration of H2O2 in the suspension 4 mM, after stirring at room temperature in the dark environment for 30 min, take the sample, centrifuge, and perform UV-vis detection; when the absorbance at 503 nm gradually increases, it indicates that the sample to be detected contains phenolic compounds or phenol; otherwise, the sample to be detected does not contain phenolic compounds and phenol.

[0023] Further, when the concentration of the polyacid-based complex for detecting phenol is 0.01-0.1 mM, the ultraviolet absorption spectrum has a good linear relationship, and the correlation coefficient is 0.999, and the detection limit of the polyacid-based complex for detecting phenol is calculated as 0.36 µM.

[0024] Further, the polyacid-based complex respectively detects phenolic compounds 4-chlorophenol, o-methylphenol, p-nitrophenol and m-phloroglucinol, and all have good linear relationships, and the correlation coefficients are 0.999, 0.999, 0.994 and 0.996 respectively, and the corresponding detection limits are 1.89 µM, 2.12 µM, 1.67 µM and 5.02 µM respectively.

[0025] The polyacid-based complex is synthesized by using Cu(NO3)2·3H2O, 3-(3-pyridine) acrylic acid, H4[SiW 12 O 40 ]·xH2O, 1,4-naphthalene dicarboxylic acid and 1,2-propanediamine as raw materials.

[0026] (1) The synthesis method is simple, the synthesis period is short, and the synthesis yield is high. The 3-(3-pyridine) acrylic acid ligand used has N-containing groups and oxygen-containing groups, is easy to coordinate with copper ions, accelerates the crystallization process of the polyacid-based complex, and shortens the synthesis period. The synthesized polyacid-based complex has high crystallinity and clear structure, and is easy to separate from the reaction medium.

[0027] (2) The synthesized polyacid-based complex {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O can be used as a catalyst for detecting phenolic compounds and trace phenol in the environment. The detection limit of the polyacid-based complex for detecting phenol is as low as 0.36 µM; the detection limits of the polyacid-based complex for detecting 4-chlorophenol, o-methylphenol, p-nitrophenol and m-phloroglucinol are 1.89 µM, 2.12 µM, 1.67 µM and 5.02 µM respectively, the detection limit is low, and the anti-interference performance is good. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The present invention is {[Cu(dap)(3-PA)]4(SiW) 12 O 40 Infrared spectrum of )(H2O)2·2H2O;

[0029] Figure 2 The present invention is {[Cu(dap)(3-PA)]4(SiW) 12 O 40 Powder line diffraction pattern of )(H2O)2·2H2O;

[0030] Figure 3 The present invention is {[Cu(dap)(3-PA)]4(SiW) 12 O 40 Coordination environment diagram of )(H2O)2}·2H2O;

[0031] Figure 4 The present invention is {[Cu(dap)(3-PA)]4(SiW) 12 O 40 A one-dimensional chain diagram of )(H2O)2·2H2O;

[0032] Figure 5 The present invention is {[Cu(dap)(3-PA)]4(SiW) 12 O 40 Two-dimensional supramolecular layer diagram of )(H2O)2·2H2O;

[0033] Figure 6 The present invention is {[Cu(dap)(3-PA)]4(SiW) 12 O 40 )(H2O)2}·2H2O detection of peroxidase-like activities of phenolic compounds;

[0034] Figure 7 The present invention is {[Cu(dap)(3-PA)]4(SiW) 12 O 40 Blank control diagram for detecting peroxidase-like activity of phenolic compounds using (H2O)2·2H2O;

[0035] Figure 8 The present invention is {[Cu(dap)(3-PA)]4(SiW) 12 O 40 (H₂O)₂·2H₂O as a mechanism diagram for peroxidase simulation experiments;

[0036] Figure 9 The present invention is {[Cu(dap)(3-PA)]4(SiW)12 O 40 )2}·2H2O after adding phenolic compounds with different concentrations;

[0037] Figure 10 {[Cu(dap)(3-PA)]4(SiW 12 O 40 )2}·2H2O after adding phenolic compounds with different concentrations;

[0038] Figure 11 {[Cu(dap)(3-PA)]4(SiW 12 O 40 )2}·2H2O after adding phenolic compounds with different concentrations;

[0039] Figure 12 {[Cu(dap)(3-PA)]4(SiW 12 O 40 )2}·2H2O for phenolic compound detection;

[0040] Figure 13 {[Cu(dap)(3-PA)]4(SiW 12 O 40 )2}·2H2O after catalytic reaction;

[0041] Figure 14 {[Cu(dap)(3-PA)]4(SiW 12 O 40 )2}·2H2O after catalytic reaction. DETAILED DESCRIPTION

[0042] {[Cu(dap)(3-PA)]4(SiW 12 O 40 )2}·2H2O, wherein dap is 1,2-propanediamine; 3-HPA is 3-(3-pyridyl) acrylic acid, 3-PA is a carboxyl group of 3-(3-pyridyl) acrylic acid losing one proton; and the structural formula of 3-(3-pyridyl) acrylic acid is:

[0043] 2.07 mmol of Cu(NO3)2·3H2O, 0.17 mmol of H4[SiW 12 O 40·xH₂O, 2.68 mmol 3-(3-pyridine)acrylic acid, 0.92 mmol 1,4-naphthalenedicarboxylic acid, 0.2 mL 1,2-propanediamine, 4 mL water, and 2 mL acetonitrile were sequentially added to a 25 mL stainless steel autoclave lined with polytetrafluoroethylene. After stirring at room temperature for two hours, the temperature was increased to 120 °C at a rate of 10 °C / h and kept at this temperature for 4 days. Then, the temperature was decreased to room temperature at a rate of 10 °C / h to obtain blue blocky crystals. These crystals were washed three times with a mixture of acetonitrile and water in a volume ratio of 1:2 and then dried to obtain the polyacid complex {[Cu(dap)(3-PA)]₄(SiW 12 O 40 {[Cu(dap)(3-PA)]4(SiW)2}·2H2O (polyacid complex 1), the yield was tested to be 54%. The 1,4-naphthalenedicarboxylic acid ligand in the raw materials did not appear in this polyacid complex {[Cu(dap)(3-PA)]4(SiW)2}·2H2O (polyacid complex 1). 12 O 40 In the structure {(H2O)2}·2H2O, if the 1,4-naphthalenedicarboxylic acid ligand is removed during the synthesis process, while other aspects remain the same as in Example 1, the polyacid complex {[Cu(dap)(3-PA)]4(SiW)} will not be obtained after the reaction. 12 O 40 )(H2O)2}·2H2O.

[0044] I. Example 1 Synthesized polyacid complex {[Cu(dap)(3-PA)]4(SiW 12 O 40 Characterization of (H2O)2·2H2O (polyacid complex 1)

[0045] (1) Infrared Spectroscopy

[0046] The infrared spectra of the complex materials were tested using an FT-IR spectrometer, with a scanning range of 500–4000 cm⁻¹. -1 ;like Figure 1 The characteristic absorption peak of the polyacid shown is at 999 cm⁻¹. -1 -873cm -1 The ν(-NH2) absorption peak in 1,2-propanediamine appears at 2869-2954 cm⁻¹. -1 The ν(-CH2) absorption peak appears at 1441-1555 cm⁻¹. -1 This indicates that the complex was synthesized from the corresponding raw materials.

[0047] (2) Powder diffraction

[0048] The powder diffraction data were collected on a Rigaku Ultima IV powder X-ray diffractometer with an operating current of 40 mA and a voltage of 40 kV; a molybdenum target X-ray was used; fixed scan, receiving slit width was 0.1 mm; the density data collection scan range was 5° to 50°, the scan speed was 5° / s, and the span was 0.02° / time; the data fitting used the Cerius2 program, and the single crystal structure powder diffraction spectrum simulation conversion used Mercury 1.4.1.

[0049] As shown in FIG. 1, the powder X-ray diffraction spectrum of the polyacid-based complex 1 is basically consistent with the fitted PXRD spectrum, indicating that the polyacid-based complex 1 is a pure phase. Figure 2

[0050] II. Crystal structure determination of the polyacid-based complex { [Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O (polyacid-based complex 1) synthesized in Example 1

[0051] A single crystal of appropriate size was selected under a microscope, and diffraction data were collected at room temperature using a Bruker SMART APEX II diffractometer (graphite monochromator, Mo-Ka, ) with a scan mode The diffraction data were corrected for absorption using the SADABS program; data reduction and structure analysis were completed using the SAINT and SHELXTL programs, respectively; the coordinates of all non-hydrogen atoms were determined by least squares method, and the positions of hydrogen atoms were obtained by theoretical hydrogenation; the crystal structure was refined by least squares method; Figures 3-5 showing the basic coordination and extended structure of the polyacid-based complex 1 synthesized in Example 1; part of the parameters of the crystallographic diffraction point data collection and structure refinement of the polyacid-based complex 1 are shown in Table 1:

[0052] Table 1 Crystal data table of the polyacid-based complex 1

[0053]

[0054]

[0055] III. Peroxidase-like activity experiment of the polyacid-based complex { [Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O (polyacid-based complex 1) synthesized in Example 1

[0056] The peroxidase-like enzyme activity was studied by the catalytic reaction of 4-aminoantipyrine and phenol; the specific scheme is as follows:

[0057] ​The 4-aminoantipyrine and polyoxometalate complex {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O was dispersed in 3 mL of water, and the concentrations of 4-aminoantipyrine and polyoxometalate complex were 2 mg·mL -1 , 0.5 mg·mL -1 , respectively. Then, phenol and H2O2 were added to the above mixture in turn, and the concentrations of phenol and H2O2 in the mixture were 6 mM and 5 mM, respectively. After the reaction for 30 min at room temperature, i.e., 25°C, in the dark, the absorbance of the reaction solution at 503 nm was recorded by UV-vis testing (Table 2).

[0058] Table 2 Experimental scheme for the peroxidase-like activity of polyoxometalate complex 1

[0059]

[0060] As shown in Table 2 and Figure 6 , the system of phenol + 4-aminoantipyrine + H2O2 + polyoxometalate complex 1 has a significant absorption peak at 503 nm, indicating that the polyoxometalate complex 1 can act as a peroxidase mimic to catalyze the hydrogen peroxide reaction of phenol and 4-aminoantipyrine to form quinone imine.

[0061] Four, the polyoxometalate complex {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O (polyoxometalate complex 1) synthesized in Example 1 was used as a blank control experiment for peroxidase-like activity

[0062] To verify the catalytic effect of the polyoxometalate complex 1, 0.4 μmol of the same molar mass of polyoxometalate complex 1, H4[SiW 12 O 40 ]·xH2O, 3-(3-pyridyl) acrylic acid, and Cu(NO3)2·3H2O were added to the system of 4-aminoantipyrine, phenol, and oxidant H2O2, respectively. After the reaction for a certain time at room temperature, i.e., 25°C, the absorbance of the reaction solution at 503 nm was recorded by UV-vis testing (Table 3).

[0063] Table 3 Blank control experiment for peroxidase-like activity of polyoxometalate complex 1

[0064] Serial number Catalyst Absorbance 1 Polyacid-based complex 1 0.55 2 [H4[SiW 12 O 40 ]·xH2O]]> 0.07 3 [Cu(NO3)2·3H2O] 0.21 4 3-(3-pyridyl) acrylic acid 0.15

[0065] The reaction conditions were as follows: the concentration of phenol was 6 mM, the amount of substance of the catalyst was 0.4 μmol, and the concentration of 4-aminoantipyrine was 2 mg·mL -1, the concentration of H2O2 was 5 mM, room temperature, dark, 30 min.

[0066] As shown in Table 3 and Figure 7 Fig. 2, the absorbance of UV spectrum of each solution followed the order of polyoxometalate-based complex 1 > Cu(NO3)2·3H2O > 3-(3-pyridyl) acrylic acid > H4[SiW 12 O 40 ]·XH2O. The experimental results showed that the activity of polyoxometalate-based complex 1 as peroxidase mainly came from the coordination of Cu 2+ and 3-(3-pyridyl) acrylic acid, and the increase of absorbance might be due to the synergistic effect of metal and 3-(3-pyridyl) acrylic acid.

[0067] Five, the synthesis of polyoxometalate-based complex { [Cu (dap) (3-PA) ]4 (SiW 12 O 40 ) (H2O) 2}·2H2O (polyoxometalate-based complex 1) as peroxidase catalytic reaction mechanism phthalic acid (TA) as a fluorescent probe for ·OH identification. The catalyst polyoxometalate-based complex 1 and TA were added to a 5 mL centrifuge tube, water was added to 3 mL, and then the oxidant H2O2 was added. The reaction was carried out in the dark at room temperature, i.e. 25℃ for 12 h and centrifuged. The fluorescence spectrum of the mixed solution was detected under the excitation wavelength of 326 nm.

[0068] Experimental group 1

[0069] Phthalic acid was added to a 5 mL centrifuge tube, water was added to 3 mL to make its concentration 0.5 mM, and ultrasonic was carried out for 5 min. The reaction was carried out in the dark for 12 h and centrifuged. The fluorescence spectrum of the mixed solution was detected under the excitation wavelength of 326 nm, and no obvious absorption peak appeared at 420 nm.

[0070] Experimental group 2

[0071] Phthalic acid and polyoxometalate-based complex 1 were added to a 5 mL centrifuge tube, water was added to 3 mL to make the concentration of phthalic acid and polyoxometalate-based complex 1 0.5 mM and 0.5 mg·mL -1 , respectively. After ultrasonic for 5 min, the reaction was carried out in the dark for 12 h and centrifuged. The fluorescence spectrum of the mixed solution was detected under the excitation wavelength of 326 nm, and no obvious absorption peak appeared at 420 nm.

[0072] Experimental group 3

[0073] Phthalic acid was added to a 5 mL centrifuge tube, water was added to 3 mL to make its concentration 0.5 mM, after ultrasonic for 5 min, H2O2 was added to make its concentration 5 mM, reacted for 12 h in the dark and centrifuged, the fluorescence spectrum of the mixed solution was detected at an excitation wavelength of 326 nm, and an absorption peak appeared at 420 nm.

[0074] Experimental group 4

[0075] Phthalic acid and polyacid-based complex 1 were added to a 5 mL centrifuge tube, water was added to 3 mL to make the concentrations of phthalic acid and polyacid-based complex 1 0.5 mM and 0.5 mg·mL -1 , respectively, after ultrasonic for 5 min, the mixed solution was obtained, H2O2 was added to make the concentration of H2O2 in the mixed solution 5 mM, reacted for 12 h in the dark and centrifuged, the fluorescence spectrum of the mixed solution was detected at an excitation wavelength of 326 nm, and an obvious absorption peak appeared at 420 nm.

[0076] As shown in Figure 8 , an absorption peak appeared at 420 nm in experimental group 3 and experimental group 4, and the absorption peak appeared in experimental group 4 was much higher than that in experimental group 3. The results showed that polyacid-based complex 1 could act as a peroxidase to catalyze the decomposition of hydrogen peroxide to produce ·OH. Because ·OH has strong oxidizing ability, it can extract electrons from the hydroxyl group of phenol to generate quinone free radicals; leading to the oxidative coupling of 4-aminoantipyrine and quinone free radicals to produce pink quinone imine.

[0077] Six, polyacid-based complex {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O (polyacid-based complex 1) synthesized in example 1 for the best condition exploration of colorimetric detection of phenolic compounds

[0078] In order to better utilize the peroxidase activity of polyacid-based complex 1, the experimental conditions were optimized within a certain range. The catalytic efficiency of polyacid-based complex 1 as a catalyst depends on the amount of 4-aminoantipyrine, pH, the amount of catalyst and hydrogen peroxide, and the specific experimental scheme is shown in Table 4.

[0079] Table 4 Best condition exploration experiment table of polyacid-based complex 1 for colorimetric detection of phenolic compounds

[0080]

[0081] Reaction conditions: the concentration of phenol is 6 mM, the reaction temperature is 25℃, and the reaction time is 30 minutes.

[0082] As shown in Figure 9The optimal conditions for the colorimetric detection of phenolic compounds by the polyoxometalate-based complex 1 were as follows: the concentration of 4-aminoantipyrine was 1.5 mg / mL, the pH of the solution was 3, the concentration of the catalyst was 0.1 mg·mL -1 , and the concentration of hydrogen peroxide was 4 mM.

[0083] Seven, the polyoxometalate-based complex { [Cu (dap) (3-PA) ]4 (SiW 12 O 40 )(H2O)2}·2H2O (polyoxometalate-based complex 1) for the colorimetric detection of phenolic compounds

[0084] The colorimetric detection method of the polyoxometalate-based complex 1 for phenolic compounds is as follows: the polyoxometalate-based complex { [Cu (dap) (3-PA) ]4 (SiW 12 O 40 )(H2O)2}·2H2O is used as a catalyst and is placed in a reactor, 4-aminoantipyrine, deionized water, phenolic compounds, and oxidant H2O2 are sequentially added to the reactor, and the reaction is stirred at room temperature 25℃ for a certain period of time, the reaction is stopped, and the sample is taken for UV-vis detection, and the detection limit (LOD, Figures 10-11 ) of the phenolic compound is calculated according to the UV-vis result.

[0085]

[0086] Wherein, S / N is the signal-to-noise ratio, usually 3, σ is the standard deviation, and k is the linear regression slope.

[0087] Phenol experimental group 1

[0088] The polyoxometalate-based complex 1 and 4-aminoantipyrine are added to a 5 mL centrifuge tube, water is added to make the volume 3 mL, so that the concentrations of the above-mentioned substances are 0.1 mg·mL -1 , 1.5 mg·mL -1 , respectively, and then different concentrations of phenol (0.01-0.1 mM) are sequentially added. The solution pH is adjusted to 3 with 1M hydrochloric acid, H2O2 is added after ultrasonic treatment for 5 min, so that the concentration of H2O2 is 4 mM, and after stirring at room temperature for 30 min, the sample is taken and its absorbance is tested by UV-vis, and the detection limit of phenol is calculated to be 0.36 μM.

[0089] 4-chlorophenol experimental group 2

[0090] The polyoxometalate-based complex 1 and 4-aminoantipyrine are added to a 5 mL centrifuge tube, water is added to make the volume 3 mL, so that the concentrations of the above-mentioned substances are 0.1 mg·mL -1 , 1.5 mg·mL -1Then, different concentrations of 4-chlorophenol (0.01-0.1 mM) were added in turn. The solution was adjusted to pH = 3 with 1 M hydrochloric acid, and H2O2 was added after ultrasonic treatment for 5 min, to a concentration of 4 mM. After stirring at room temperature for 30 min, samples were taken, and the absorbance was tested by UV-vis. The detection limit of 4-chlorophenol was calculated to be 1.89 μM.

[0091] o-Methylphenol experimental group 3

[0092] The polyacid-based complex 1 and 4-aminoantipyrine were added to a 5 mL centrifuge tube, and water was added to make the volume 3 mL, so that the concentrations of the above substances were 0.1 mg·mL-1 and 1.5 mg·mL-1, respectively. -1 -1 Then, different concentrations of o-methylphenol (0.01-0.1 mM) were added in turn. The solution was adjusted to pH = 3 with 1 M hydrochloric acid, and H2O2 was added after ultrasonic treatment for 5 min, to a concentration of 4 mM. After stirring at room temperature for 30 min, samples were taken, and the absorbance was tested by UV-vis. The detection limit of o-methylphenol was calculated to be 2.12 μM.

[0093] Nitrophenol experimental group 4

[0094] The polyacid-based complex 1 and 4-aminoantipyrine were added to a 5 mL centrifuge tube, and water was added to make the volume 3 mL, so that the concentrations of the above substances were 0.1 mg·mL-1 and 1.5 mg·mL-1, respectively. -1 -1 Then, different concentrations of p-nitrophenol (0.01-0.1 mM) were added in turn. The solution was adjusted to pH = 3 with 1 M hydrochloric acid, and H2O2 was added after ultrasonic treatment for 5 min, to a concentration of 4 mM. After stirring at room temperature for 30 min, samples were taken, and the absorbance was tested by UV-vis. The detection limit of p-nitrophenol was calculated to be 1.67 μM.

[0095] Mesitylene experimental group 5

[0096] The polyacid-based complex 1 and 4-aminoantipyrine were added to a 5 mL centrifuge tube, and water was added to make the volume 3 mL, so that the concentrations of the above substances were 0.1 mg·mL-1 and 1.5 mg·mL-1, respectively. -1 -1 Then, different concentrations of mesitylene (0.01-0.1 mM) were added in turn. The solution was adjusted to pH = 3 with 1 M hydrochloric acid, and H2O2 was added after ultrasonic treatment for 5 min, to a concentration of 4 mM. After stirring at room temperature for 30 min, samples were taken, and the absorbance was tested by UV-vis. The detection limit of mesitylene was calculated to be 5.02 μM.

[0097] Eight, the polyacid-based complex {[Cu(dap)(3-PA)]4(SiW 12 ​​​O 40

[0098] Table 5 Anti-interference performance of polyacid-based complex 1 for colorimetric detection of phenol compounds

[0099]

[0100]

[0101] Reaction conditions: the concentrations of phenol and interfering substances were 6 mM, the concentration of catalyst was 0.1 mg·mL -1 , the concentration of 4-aminoantipyrine was 1.5 mg·mL -1 , and the concentration of H2O2 was 4 mM, and the reaction was carried out at room temperature for 30 minutes.

[0102] As shown in Table 5 and Figure 12 , when ethanol, acetone, sodium chloride and 2-ethylimidazole were added to the system of polyacid-based complex 1 + 4-aminoantipyrine + H2O2, it was found that the influence on the detection of phenol was not great, indicating that polyacid-based complex 1 had good anti-interference performance for the detection of phenol. In addition, the IR( Figure 13 ) and PXRD( Figure 14 ) of polyacid-based complex 1 before and after the detection of phenol compounds did not change significantly, indicating that polyacid-based complex 1 had good stability.

[0103] The above merely illustrates the specific embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A polyacid-based complex, characterized in that: The complex is used as a catalyst for detecting trace phenolic compounds by the aminoantipyrine colorimetric method, and has the following molecular formula: {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O; wherein dap is 1,2-propanediamine; 3-HPA is 3-(3-pyridyl) acrylic acid, and 3-PA is a carboxyl group of 3-(3-pyridyl) acrylic acid from which one proton is removed; The complex crystallizes in a triclinic system with space group P -1, with the following unit cell parameters: a = 11.8171(3) Å, b = 12.4810(3) Å, c = 14.6202(4) Å, α = 86.7550(10) ° , β = 81.6790(10) ° , γ = 71.5250(10) ° , and a unit cell volume of V= 2023.53(9) Å 3 , with a number of formula units of Z = 1, corresponding to the molecular formula C 44 H 70 Cu4N 12 O 52 SiW 12 .

2. A process for the preparation of a polyacid-based complex as claimed in claim 1, characterized by: Specific steps are as follows: In step (2), the heating and cooling rates are both 10℃ / h, and the flushing times of the acetonitrile aqueous solution are 3 times. (1) Cu(NO3)2.3H2O, 3-(3-pyridyl) acrylic acid, H4[SiW 12 O 40 ] x H2O, 1,4-naphthalene dicarboxylic acid and 1,2-propanediamine were added into an aqueous solution of acetonitrile, stirred at room temperature for 2 h to obtain a mixed solution; wherein, Cu(NO3)2.3H2O, 3-(3-pyridyl) acrylic acid, 1,4-naphthalene dicarboxylic acid and H4[SiW 12 O 40 ] x H2O in a molar ratio of 12.2:1, 15.8:1, 5.4:1, respectively, H4[SiW 12 O 40 ] x H2O and 1,2-propanediamine in a molar volume ratio of 0.85 mol / L, and the aqueous solution of 1,2-propanediamine and acetonitrile in a volume ratio of 1:30; (2) The above mixed solution was added to a stainless steel autoclave with a polytetrafluoroethylene inner liner, heated to 120°C, and kept for 4 days, and then cooled to obtain blue block-shaped crystals. After being washed with an acetonitrile aqueous solution, a polyacid-based complex {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O was obtained.

3. The method for producing a polyacid-based complex according to claim 2, characterized by: In steps (1) and (2), the volume ratio of acetonitrile to water in the acetonitrile aqueous solution is 1:

2.

4. The polyacid-based complex of claim 2, characterized by: The phenolic compound is phenol, 4-chlorophenol, o-methylphenol, p-nitrophenol or phloroglucinol.

5. Use of the polyacid-based complex according to claim 1 for detecting phenolic compounds, characterized in that: μ 6. Use of the polyacid-based complex according to claim 5 for detecting phenolic compounds, characterized in that: The polyacid-based complex can detect the concentration of phenol in the range of 0.01-0.1 mM, the correlation coefficient is 0.999, and the detection limit of phenol is 0.36 μ M.

7. Use of the polyacid-based complex according to claim 5 for detecting phenolic compounds, characterized in that: The polyacid-based complexes respectively detect phenolic compounds 4-chlorophenol, o-methylphenol, p-nitrophenol and phloroglucinol, the correlation coefficients are 0.999, 0.999, 0.994 and 0.996 respectively, and the corresponding detection limits are 1.89 μ M, 2.12 μ M, 1.67 μ M and 5.02 The polyacid-based complex is used as a catalyst for detecting phenolic compounds by the aminoantipyrine colorimetric method. M.

8. Use of the polyacid-based complex according to claim 5 for detecting phenolic compounds, characterized in that: The steps for detecting phenolic compounds are as follows: (3) The sample to be detected is added to the suspension obtained in step (2), and then H2O2 is added to make the concentration of H2O2 in the suspension 4mM. After stirring at room temperature in the dark for 30min, the sample is taken, centrifuged, and subjected to UV-vis detection. When the absorbance at 503nm gradually increases, it indicates that the sample to be detected contains phenolic compounds; otherwise, the sample to be detected does not contain phenolic compounds. (1) After grinding the polyoxometalate-based complex {[Cu(dap)(3-PA)]4(SiW 12 O 40 )(H2O)2}·2H2O, a polyoxometalate-based complex powder is obtained; (2) dispersing the polyacid-based complex powder and 4-aminoantipyrine into 3 mL of water to prepare a suspension with a polyacid-based complex powder concentration of 0.1 mg·mL -1 and a 4-aminoantipyrine concentration of 1.5 mg·mL -1 , adjusting the pH of the solution to 3 with 1 M hydrochloric acid, and ultrasonically dispersing at room temperature for 5 min to obtain a suspension; ​

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