CN115728251A - Application of cholesteric artificial receptor for specifically recognizing silver ions - Google Patents

Abstract

The application of the specific recognition silver ion of the cholesteric artificial receptor. The invention provides a silver ion detection method, which comprises the step of using a sample to be detected and simultaneously containing-COOCH ₃ and-ArOCH ₃ And (4) carrying out pretreatment on the molecular clamp of the two functional groups, and then detecting. Establishes Ag in a practical sample ⁺ The detection method has the advantages of sensitivity, high efficiency, simple operation compared with the traditional method, shortened detection time and low cost of required instruments and equipment, so that the Ag is expected to be developed based on the method ⁺ The rapid detection kit is applied to silver ion detection in the fields of food, environment and the like.

Description

Application of specific recognition silver ion of cholesteric artificial receptor

Technical Field

The invention relates to the field of detection, in particular to detection of metal ions.

Background

It is known that metal ions are applied to daily life everywhere, and particularly play an irreplaceable role in the fields of food, environment, medical treatment and the like. However, due to the insufficient prevention of negative effects brought by the rapid development of the economic society, a large amount of untreated toxic and harmful ions are discharged into the environment without restriction, and then enter the human body through the food chain, thus harming the human health. The transition metal silver is one of important trace elements existing in nature, and is now widely used in photography and semiconductor materials due to its optical properties. Scientific research shows that silver ions with a certain concentration show good bactericidal effect, can be used for producing disinfectants, and has been successfully applied to prevention and treatment of diseases and research and development of antibacterial drugs. Although Ag ⁺ Shows beneficial effects, but once accumulated in the body continuously over a safe concentration, the thiol-group in various metabolites can interact with each other to inactivate the sulfurase, thereby causing serious adverse effects on human health, such as inhibition of cell proliferation and differentiation, induction of skin tissue damage, liver and kidney failure, mitochondrial dysfunction and the like. Therefore, the development of a recognition receptor with high sensitivity response of silver ions and a reliable detection method have important significance on human health and food safety. At present, the detection of silver ions is usually limited to traditional analysis methods, such as Atomic Absorption Spectroscopy (AAS), atomic Emission Spectroscopy (AES), inductively coupled plasma mass spectrometry (ICP-MS), ion selective electrode method (ISE), and the like, but these methods all rely on large-scale precision instruments and specialized technicians, and are cumbersome to operate, thereby seriously hindering the conventional and field detection capabilities. Today, photochemistryThe technology is gradually developed into a detection method with wide application prospect, the method not only has high selectivity and high sensitivity required by detection technology, but also has cheap required instruments and equipment, and environmental-friendly and efficient experimental operation, and accords with the concept of green chemical detection.

In recent years, the kind of cation-specific recognition receptor based on the formation of photochemical response signals has been reported in large quantities year by year. Jiahui 21180 ²⁺ A fluorescent probe recognizing that Cu can be detected with high selectivity in an aqueous acetonitrile solution ²⁺ Ions. Wang et al synthesized a dipyrene derivative using a pyrene molecule and a pyridine molecule, and found that the compound was specific to Ag by a fluorescence test ⁺ Good selectivity is shown. Chen and the like synthesize p-Pd by taking coumarin as a base ²⁺ High selectivity and sensitivity fluorescent probes.

Disclosure of Invention

The invention aims to provide a method for detecting silver ions in products such as food, medicines, health-care products and the like.

The research of the invention finds that the application contains-COOCH ₃ and-ArOCH ₃ The molecular clamp with two functional groups can be combined with silver ions, has selective recognition capability on the silver ions, can better distinguish the silver ions from other metal ions, can distinguish whether the silver ions exist or not by observing colors through naked eyes after combination, and can perform qualitative or quantitative detection through fluorescence, ultraviolet and other spectroscopy.

The molecular clamp of the present invention includes, but is not limited to:

through research, the methoxy oxygen atom connected with the benzene ring in the molecular clamp 7a and Ag ⁺ Has a shortest distance of

12α-COOCH ₃ Of carbonyl oxygen atoms with Ag ⁺ Has a shortest distance of

It is thus assumed that 12 α -COOCH ₃ And ArOCH ₃ Oxygen atoms of radicals with Ag ⁺ And act to form a complex.

The method for digesting the sample to be detected by a wet method is a method for destroying organic matters or reducing substances in the sample by using acid liquor or alkali liquor under a heating condition.

In the present invention, digestion may be carried out with an acid solution, for example, sulfuric acid and salts thereof.

The color can be distinguished by naked eye detection, namely, by naked eye visualization without using other instruments and equipment.

Drawings

FIG. 1 (A) color change of a host compound 7a with different metal ions added; (B) Ultraviolet-visible absorption spectrum of host compound 7a added with different metal ions

FIG. 2 shows fluorescence spectra of host compound 7a after adding different metal ions

FIG. 3 recognition of Ag for the body 7a by other metal ions ⁺ Influence of change in fluorescence intensity of

FIG. 4 host compound 7a vs Ag at different pH values ⁺ Fluorescence response of

FIG. 5 shows host compound 7a with Ag ⁺ 1/[ G ] of Complex formation ₀ ]Plotting 1/Δ A

FIG. 6 host Compound 7a (1.0X 10) ^-4 mol/L) at different concentrations of Ag ⁺ (0-20 mu mol/L) ultraviolet-visible spectrum diagram

FIG. 7 shows host compounds 7a and Ag ⁺ Coordinated Job plot

FIG. 8 (A) host Compound 7a in the absence of Ag ⁺ FESEM image under the conditions (. Times.300,5kw) (B) Ag for the host compound 7a ⁺ FESEM image in the Presence (. Times.10000,5kw.) of (C) host Compound 7a in Ag ⁺ FESEM image in presence (x 20000, 25 kw) (D) host compound 7a in Ag ⁺ Energy spectrum image in the presence (× 20000, 25 kw)

FIG. 9. Complex 7a +Ag ⁺ Mass spectrum of

FIG. 10. Host compound 7a and complex 7a + Ag ⁺ In the infrared spectrum

FIG. 11 host compound 7a in DMSO-d ₆ Adding Ag in different proportions ⁺ Is ¹ H NMR spectrum: (A) +1 equivalent; (B) +0 equivalents, (. Diamond-solid., NCH;

12α-COOCH ₃ ；·，ArOCH ₃ ；)

FIG. 12 shows main body molecular tweezer 7a and complex 7a + Ag ⁺ Minimum energy constellation diagram of

FIG. 13 shows the main molecular clamp 7a and Ag ⁺ Possible complexation model

FIG. 14.Ag ⁺ Quantitative detection standard curve

Detailed Description

Example 1

1 test part

1.1 reagents and instruments

Deoxycholic acid, o-methoxybenzoic acid, and triphosgene (not less than 99%) are purchased from Shanghai Aladdin Biotechnology, inc.; methanol, ethanol, concentrated hydrochloric acid, dichloromethane and ethyl acetate are purchased from Fuyu fine chemical engineering Co., ltd, tianjin; acetone was purchased from Jiang Shunhua engineering and technology Co., ltd, guangzhou; anhydrous sodium sulfate was purchased from mao chemical reagent factory, tianjin; pyridine (more than or equal to 99 percent) is purchased from Shanghai Jianxin chemical industry Co., ltd; hydrazine hydrate was purchased from Guangdong Guanghua technologies, inc.; deuterated DMSO was purchased from merck chemicals, inc; tris (tris) was purchased from Guangzhou Sai Biotechnology, inc.; the metal ion solution is prepared from nitrate or acetate thereof; milk powder was purchased from double city Nestle Co., ltd; fructus Lycii and rhizoma quinoa are purchased from commercial GmbH of Germina Mulberry; wheat flour was purchased from commercial and trade companies in Jinshahe, hebei; all the reagents are analytically pure, and all the test water is distilled water.

Ultraviolet absorption spectrum was measured with a UV-2600 type ultraviolet-visible spectrophotometer (Shimadzu instruments Co., ltd., japan); measurement of fluorescence emission spectrum with an RF-6000 type fluorescence photometer (Shimadzu instruments Co., ltd., japan); mass spectrometry was performed using a Thermo Q active ultra high resolution lc/lc instrument (siemer femoris technologies ltd, usa); performing a chemical reaction using an MCR-3 microwave chemical reactor (Zheng Zhou Tai Yuan instruments, ltd.); nuclear magnetic resonance spectra were recorded with an AVANCE NEO model nuclear magnetic resonance spectrometer (brueck, germany); the microscopic image was observed with a JSM-7900F field emission scanning electron microscope (Nippon electronics Co., ltd.); the infrared spectra were recorded using a Nicolet 6700 Fourier Infrared spectrometer (Sammer Feishel technologies, USA).

1.2 Synthesis of cholesteric molecular tweezer 7a

The synthesis route of the main molecular clamp 7a is shown in scheme 1, the intermediate 3 and the intermediate 5 are synthesized according to the method reported in the prior literature, the intermediate 5 (0.5 mmol/L), anhydrous dichloromethane (10 mL), anhydrous pyridine (0.5 mL) and triphosgene (0.18 mmol/L) are placed in a 50mL round-bottom flask, heating and refluxing are carried out for 10min under 300W microwave radiation, valine methyl ester hydrochloride (1 mmol/L) and anhydrous pyridine (0.5 mL) are added after the reaction is completed, the reaction is continued for 10min under the same conditions, the solvent is evaporated under reduced pressure after the reaction is completed, and the residue is separated and purified by column chromatography to obtain a white solid (C) (C is a solid) ₄₁ H ₆₁ N ₃ O ₁₀ ) The mass spectrum, hydrogen spectrum, carbon spectrum, etc. of the target are consistent with those reported in the literature (YE Y, SUO Y R, YANG F, et al. Microwave-assisted synthesis of novel chemical receptors from reactive acids and molecular receptors [ J ]].Chem Lett,2014,43:1812-1814).

1.3 preparation of solutions and spectroscopic analysis

Reference is made to: synthesis of a Shizhichuan, zhao Zhi just and an asymmetric bis-biuret thiosemicarbazide fluorescent probe and research on identification performance of the probe on metal ions [ J ] modern chemical industry, 2019,39 (09): 227-231.

Selecting 0.1mol/L of Tris (hydroxymethyl) aminomethane and hydrochloric acid, and quantitatively mixing the Tris (hydroxymethyl) aminomethane and the hydrochloric acid according to a volume ratio of 25. Molecular clamp capable of accurately weighing proper amountThe artificial receptor 7a is placed in a 25mL volumetric flask, and after being completely dissolved by 5mL of DMSO, ethanol/Tris (V/V =1/1, pH 7.0) solution is added to the volumetric flask until reaching the marked line, so that 0.1mmol/L of molecular tweezer stock solution is obtained. Respectively weighing nitrate or acetate (Ag) of metal ions ⁺ 、Al ³⁺ 、Ca ²⁺ 、Mg ²⁺ 、Na ⁺ 、K ⁺ 、Pb ²⁺ 、Mn ^{2 +} 、Zn ²⁺ 、Fe ³⁺ ) Dissolving in deionized water to prepare metal ion salt solution with concentration of 0.1 mmol/L.

At room temperature, adding a certain amount of different metal ions into the prepared molecular tweezer solution respectively, measuring the ultraviolet-visible absorption spectrum and the fluorescence spectrum (selectivity test, interference test, ultraviolet titration test and Job test) of the mixture, detecting the fluorescence spectrum in the range of 200-600 nm, and detecting the change of the ultraviolet absorption spectrum in the range of 200-400 nm.

1.4 Selective identification of Metal ions by host Compounds

And the host molecular clamp 7a is used for ultraviolet visible absorption spectrum identification tests on different metal cations. Taking 0.5mL of 1X 10 ^-4 The mol/L of the main molecular clamp 7a is added with various metal ions (Ag) with 5 times of the mass ⁺ 、Al ³⁺ 、Ca ²⁺ 、Mg ²⁺ 、Na ⁺ 、K ⁺ 、Pb ²⁺ 、Mn ²⁺ 、Zn ²⁺ 、Fe ³⁺ ) And observing the color, fluorescence emission spectrum and ultraviolet-visible absorption spectrum change of the solution.

1.5 coexisting ion Pair specificity recognition Ag ⁺ Study on the interference ability and the influence of pH

To detect if the host compound 7a interferes with Ag in the presence of other metal ions ⁺ The selective recognition is carried out, the anti-interference research of the recognition is carried out, a mixed system with different pH values is prepared, and the influence of the pH value on the fluorescence intensity of the complex is observed. The concentration of the host molecular clamp 7a is 1X 10 ^-4 Adding 5 times of Ag in mass into the solution in mol/L in sequence ⁺ And other single metal ions, and observing the change of the fluorescence emission spectrum.

1.6 recognition of Ag by Main body molecular Clamp 7a ⁺ Ultraviolet drop ofJob test and Ding

At a concentration of 1.0X 10 ^-4 Gradually dripping Ag into the solution of the main molecular clamp 7a of mol/L ⁺ (0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20. Mu. Mol/L), determination of different Ag ⁺ The ultraviolet-visible absorbance values of the compound solutions of each group under the concentration are calculated by the absorbance value of the compound at 257nm of the main molecular clamp 7a and Ag ⁺ The complexation constant of (c).

To further determine the host molecular clamp 7a versus Ag ⁺ The mixing ratio of (2) is an effective measurement method by the equimolar ratio continuous variation method (Job test method) ^[30] . Always maintain the host and the object Ag ⁺ Total concentration of (1X 10) ^-4 mol/L, preparing the main molecular clamp 7a and Ag in sequence ⁺ A series of mixed solutions with a molar ratio of 1.

1.7 microstructure observation and energy spectrum imaging research of complex

In order to more visually observe the compound 7a and Ag ⁺ For the host molecular clamp 7a and its interaction with Ag ⁺ The complex of (2) is subjected to microstructure observation and energy spectrum imaging analysis by using a Field Emission Scanning Electron Microscope (FESEM).

1.8 recognition of Ag by Main body molecular Clamp 7a ⁺ Study of the mechanism of action of

Research on Ag by using main molecular clamp 7a by means of Fourier infrared spectroscopy, nuclear magnetic titration, computer molecular simulation and the like ⁺ The mechanism of action of the recognition. Addition of Ag into main molecular clamp 7a for Fourier infrared spectrum observation ⁺ The change of the post functional group preliminarily deduces the possible binding sites of the two; quantitatively adding the molecular clamp 7a and Ag according to the composition ratio of the complex ⁺ Observe the addition of Ag to the subject molecular tweezer 7a ⁺ Rear end ¹ The change of H spectrum, further judge the molecular clamp 7a and Ag through the change of hydrogen proton chemical shift on different functional groups ⁺ The binding site and possible recognition driving force of (c); computer molecular simulation for further confirming molecular clamp 7a andAg ⁺ possible mechanism of action.

1.9 Main body fluorescent probes 7a vs. Ag ⁺ Determination of detection limits

The concentration of the host molecular clamp is 1.0X 10 ^-4 Gradually dripping Ag into the mol/L solution ⁺ When being Ag ⁺ The concentration is 2X 10 ^-6 ～2×10 ^-5 In the mol/L range, with Ag in the complex formation process ⁺ Plotting the concentration to the ultraviolet-visible absorbance value to obtain a standard curve equation, and calculating the ratio of the fluorescent probe 7a to Ag according to the formula LOD =3 sigma/k ⁺ The detection limit of (2). Where σ is the standard deviation and k is the slope of the linear fit.

1.10 Ag in food samples ⁺ Quantitative determination of

Taking milk powder, quinoa, wheat flour and medlar samples 2g respectively, drying, crushing, transferring into a dry digestion tube, adding 0.2g of copper sulfate, 6g of potassium sulfate and 10mL of sulfuric acid respectively, digesting at a high temperature of 400 ℃ for 1h, cooling to room temperature, diluting to a certain multiple, and adjusting the pH to 7.0 (refer to Xia Jun Ying, synthesis based on benzothiazole derivative fluorescent probe and performance research [ D]Bohai sea university, 2020). Main body molecular clamp 7a (1X 10) ^-4 mol/L) 0.5mL, adding 2.5mL diluted sample, mixing, measuring the absorbance value of the sample at 257nm, measuring each group for 3 times, taking the average value, and calculating Ag in each sample according to the standard curve equation obtained by 1.9 ⁺ The content of (a).

2 results and discussion

2.1 Selective identification of Metal ions by host Compounds

As shown in FIG. 1B, the probe had absorption at 235, 290nm without addition of metal ions, with a strong absorption peak at 235 nm. When the host compound reacts with metal ions, although the absorption peak intensity at the maximum ultraviolet absorption wavelength of the host compound is changed, ag ⁺ But exhibit distinctiveness. The absorption peak intensity of the metal ion at the wavelength is higher than that of other metal ions, and the ultraviolet absorption peak at 290nm is obviously red-shifted to 257 nm. This is probably due to the host compound 7a being reacted with Ag ⁺ A selective recognition effect is generated, which causes the change of the absorption peak signalWhile other metal ions do not react. In addition, it is noted that the host compound 7a is mixed with Ag ⁺ The color changed from colorless to a clear pale red after the action, and the color of other metal ions did not change (fig. 1A). This is probably due to the host compound 7a with Ag ⁺ A complex is formed, promoting the color change of the solution. This indicates that the host compound 7a can achieve macroscopic specific recognition of Ag ⁺ The effect of (1). In order to further examine the selective recognition effect of the host compound 7a on metal cations, the emission properties of the metal cations were investigated by fluorescence spectroscopy.

As shown in FIG. 2, ag is formed when different metal ions are added to the host compound 7a at the same concentrations ⁺ Shows the strongest fluorescence emission spectrum intensity change, and the other metal ions have basically no difference in response value although the fluorescence intensity of the main body at 268nm is slightly enhanced. The change results of the fluorescence spectrum and the ultraviolet spectrum show that the main molecular clamp 7a and Ag ⁺ Better specific binding is generated, and the main compound 7a can be applied to Ag ⁺ High-selectivity recognition is realized.

2.2 study of the Effect of coexisting ions on the interference ability of the specific recognition Effect and on the pH value

As shown in FIG. 3, in the host compound 7a and Ag ⁺ Adding other metal ions under the coexisting system, the fluorescence intensity is equal to that of only adding Ag ⁺ The change is not great, indicating that the host compound 7a is to Ag ⁺ Has good fluorescent response and other metal ions have good response to Ag ⁺ The selection recognition process has little effect. In addition, mixed solutions of different pH were prepared, and the effect of pH on the fluorescence intensity of the complex was observed, and the results are shown in fig. 4. Does not contain Ag ⁺ The host molecular clamp 7a showed very weak fluorescence intensity and was relatively stable, and Ag was added ⁺ Then, the fluorescence intensity shows a continuously increasing trend along with the change of pH, when the pH is equal to 6-8, the fluorescence response of the complex tends to be stable and the intensity gradually reaches a peak value and then starts to decrease, which is probably caused by influencing the space structure of the cholesterol ring of the main body under the peracid or over-alkaline environment, and meanwhile, the molecular clamp 7a of the main body and Ag simultaneously ⁺ The identified pushing force is destroyedThereby causing the fluorescence intensity of the complex solution to show significant fluctuation. Based on the above effects, study of the host molecular tweezer 7a on Ag ⁺ The identification performance of (1) was determined by selecting Ethanol/Tris solution with pH 7.0 as the detection system.

2.3 recognition of Ag by Main body molecular Clamp 7a ⁺ Ultraviolet titration and Job test results

As can be seen from FIG. 5, ag was added to the host molecular tweezer 7a ⁺ When the concentration is increased from 0 mu mol/L to 20 mu mol/L, the ultraviolet absorption spectrum of the solution has a regular rising trend, probably because the main molecular clamp 7a and the Ag which is continuously added ⁺ The complexation occurs resulting in intramolecular charge transfer, which results in a gradual increase in the ultraviolet absorbance value of the host compound at 257 nm. At 2X 10 ^-6 ～2×10 ^-5 In the mol/L range according to the Hildebrand-Benes equation ^[35] At 1/[ G ] ₀ ]Plot 1/Δ A and obtain a straight line (R) by linear fitting ² = 0.997), as shown in fig. 6, illustrating host compound 7a and Ag ⁺ Form 1 ⁴ L/mol. As shown in FIG. 7, it can be seen that [ Ag ] is present ⁺ ]/[7a+Ag ⁺ ]At 0.5, the maximum UV-Vis absorbance value was obtained, thus indicating the same for the host molecular tweezer 7a and Ag ⁺ Is complex coordinated with 1.

2.4 microstructure Observation and spectral imaging analysis of complexes

Main body molecular clamp 7a and Ag ⁺ The scanning electron microscope for electric field emission of the complex is shown in FIG. 8. As can be seen, no metal Ag was added ⁺ When ionized (FIG. 8A), the host compound 7a is mainly accumulated in a dense bulk form when combined with the metal ion Ag ⁺ After complexation (fig. 8B), the structure of compound 7a is significantly changed, forming a regular network structure, and a large number of cavities and fissures appear to convert Ag ⁺ Embedded therein to form stable molecular aggregates ^[36] . To further verify that the cavities in the figure are embedded with metallic Ag ⁺ Acceleration at 25.0kV by JSM 7900F high resolution transmission scanning electron microscopeA scanning electron microscope image of the sample was taken at voltage (fig. 8C) and a corresponding imaging plot of the energy spectrum (fig. 8D). As shown in FIG. 8C, when the host molecular clamp 7a is engaged with Ag ⁺ After the action, a large amount of silver ions enter into the cleft holes of the molecular clamp 7a, high bright points appear in the image, and the blue part in FIG. 8D is Ag through the analysis of a spectrum imaging graph ⁺ The red part is the carbon skeleton structure in the host molecular clip 7a, and as can be seen from the figure, most of the metal silver ions are successfully embedded into the cleft and are wrapped by the host compound 7a to form a stable complex.

2.5 host Compound 7a with Ag ⁺ Post-complexation mass spectrometry and infrared spectroscopy

The molecular weight of the main compound 7a is 755.33, and the theoretical value of the molecular weight of the complex [ M + H ] after silver ions are added] ⁺ 864.20, found 864.11 (FIG. 9), further confirming the main molecular tweezer 7a and Ag ⁺ A complex is formed. Main body molecular clamp 7a and complex 7a + Ag ⁺ The infrared spectrum of the main molecular clamp 7a is as shown in FIG. 10, and the stretching frequencies of the amide N-H, the methoxy C-H, the methoxy C = O, and the methoxy C-O-C in the main molecular clamp are 3372cm ^-1 、2951cm ^-1 、1737cm ^-1 、1239cm ^-1 . When it is reacted with Ag ⁺ After complexation, the host molecular clamp 7a is at 3372cm ^-1 The N-H vibration absorption peak of the amide (B) is shifted to 3437cm in the high wavenumber direction ^-1 At 2951cm ^-1 The methoxy C-H stretching vibration peak of the material moves to 2930cm ^-1 And C = O characteristic absorption peak from 1737cm ^-1 Move to 1720cm ^-1 The telescopic absorption peak of methoxyl C-O-C is from 1239cm ^-1 Moved to 1059cm ^-1 And 2951cm ^-1 、1737cm ^-1 The peak shape is obviously changed, the peak shape is reduced, and the peak intensity is weakened, so that C = O, -OCH are presumed from the above ₃ Possibly with Ag ⁺ The main functional group in which complexation occurs, ag ⁺ Electron deficiency, C = O, -OCH ₃ It is supplied with electrons, thereby causing a transfer of charge, which causes a change in the infrared spectrum.

2.6 Nuclear magnetic titration test results and analysis

From the 2.3 results, it is found that the host compound 7a is bound to Ag ⁺ Coordination ratio of1, to further explore host compound 7a with metallic Ag ⁺ The method adopts a nuclear magnetic titration method to determine that the main compound 7a is added with Ag in deuterated dimethyl sulfoxide ⁺ Front and rear ¹ H NMR change. As can be seen from FIG. 11, ag was not added ⁺ When in the main compound 7a, the main compound is-NCH, 12 alpha-COOCH ₃ And ArOCH ₃ The chemical shifts of the hydrogen protons on the groups were 4.52, 3.53 and 3.62ppm, respectively. When 1.0equiv of Ag is added ⁺ After the action, the intensity of the hydrogen proton signal peak on the aromatic ring of the host molecular clamp 7a is weakened, the intensity of the peak positioned at 4.52ppm is obviously increased, and the peak is shifted to a low field region (delta =0.1 ppm), and in addition, the ester group signal peak at delta 3.53ppm is obviously widened and strengthened. Presumably 12 α -COOCH ₃ And ArOCH ₃ Oxygen atoms in radicals to Ag ⁺ Electrons are supplied, resulting in a change in the signal peak of the adjacent hydrogen proton.

2.7 computer molecular simulation results and analysis

Performing systematic conformation search and structure optimization on host and host-guest complexes by using computer molecular model software (Chem 3D) ^[37] . Main body molecular clamp 7a and complex 7a + Ag ⁺ The lowest energy molecular conformation is shown in FIG. 12, and it can be seen that the host molecular clamp 7a is in the lowest energy conformation, i.e., clamp-shaped and Ag ⁺ Provide sufficient space for the guest Ag ⁺ Can better enter the molecular trap of the compound 7a and form a stable complex. The methoxy oxygen atom connected with the benzene ring in the main molecular clamp 7a and Ag ⁺ Has a shortest distance of

12α-COOCH ₃ Of carbonyl oxygen atoms with Ag ⁺ Has a shortest distance of

It is thus believed that 12 α -COOCH ₃ And ArOCH ₃ Oxygen atoms of radicals with Ag ⁺ The reaction is carried out to form a complex, the possible recognition driving force is the action of hydrogen bond and electrostatic attraction, and the main molecular clamp 7a and Ag ⁺ Possible complexation models such asAs shown in fig. 13.

2.8 Ag in actual sample ⁺ Quantitative detection of

Silver ion plays a non-negligible role in the growth and metabolism process of human body, so Ag in actual food samples ⁺ The detection of (2) is of great significance. Through the main molecular clamp 7a to Ag ⁺ The quantitative detection standard curve and detection limit test of the complex, and the Ag in the complex forming process ⁺ The concentration was plotted against the UV-visible absorbance (FIG. 14), and the standard curve equation at 257nm was fitted to be y =0.014x +0.359 and the correlation coefficient was 0.991, and the host molecular tweezers 7a were calculated for Ag according to the formula LOD =3 σ/k ⁺ The detection limit of (2) is 1.0. Mu. Mol/L.

To verify the method on Ag ⁺ The practicability of the detection is that after the nitrified food sample is diluted by a plurality of times, the food sample is subjected to a titration test by Ag ⁺ Calculating Ag in the food sample by using the standard curve ⁺ The results are shown in Table 1. Compared with AAS method, the Ag of milk powder, wheat flour, quinoa and medlar detected by the main molecular clamp 7a ⁺ The contents are respectively 19.44, 31.06, 41.4 and 38.37 mu g/g. In addition, based on the results, two of the food samples were randomly selected for their Ag using standard addition methods ⁺ The content is detected by adding Ag with different concentrations into the diluted solution ⁺ The UV absorbance values of the standard solutions (10. Mu.g/g, 40. Mu.g/g) were measured, and the results are shown in Table 2. The recovery rate is 99-104%, and the relative standard deviation is 1.34-4.59%. The relative error value between the detection result of the test and the atomic absorption method is less than 5 percent (n = 3), which proves that the method has better accuracy and can be used for Ag in different food samples ⁺ The quantitative detection of (2) has higher practicability and reliability in the analysis of actual samples.

TABLE 1 Ag in food samples ⁺ Comparison of the novel measurement method with the atomic absorption method (n = 3)

TABLE 2 Ag in the labeled food samples ⁺ Determination of the recovery (n)＝3)

3 conclusion

The research synthesizes the chiral cholesteric molecular clamp 7a, and the ultraviolet titration and fluorescence spectrum examine the chiral cholesteric molecular clamp on Ag ⁺ The research result shows that the host molecular clamp 7a can specifically recognize the metal Ag in the Ethanol/Tris (V/V =1/1, pH 7.0) solution ⁺ With a binding constant of 1.38X 10 ⁴ L/mol, the lowest detection limit is 1.0 mu mol/L, and the naked eye detection of silver ions is realized through the change of the solution color from colorless to light red. The main molecular clamp 7a is used for researching Ag by means of Fourier infrared spectroscopy, nuclear magnetic titration, computer molecular simulation and the like ⁺ The mechanism of action of (2) was found to be 12. Alpha. -COOCH in the host molecular tweezer 7a ₃ And ArOCH ₃ Is the main binding site, the oxygen atom in the group is Ag ⁺ Providing electrons, and recognizing the pushing acting force mainly including electrostatic attraction and hydrogen bond action. In addition, the Ag in food samples such as quinoa and wheat flour is added ⁺ The determination of (1) establishes a practical sample of Ag ⁺ The detection method has the advantages of sensitivity, high efficiency, simple operation compared with the traditional method, shortened detection time and low cost of required instruments and equipment, so that the Ag is expected to be developed based on the method ⁺ The rapid detection kit is applied to silver ion detection in the fields of food, environment and the like.

Claims (10)

1. The detection method of the silver ions is characterized by comprising the following steps: comprises that a sample to be detected contains-COOCH ₃ and-ArOCH ₃ The molecular clamp of the two functional groups is pretreated and then detected.

2. The detection method according to claim 1, characterized in that: the molecular clamp is selected from the following structural formulas:

3. the detection method according to claim 1, characterized in that: the pretreatment comprises the following steps: after a sample to be detected is digested, the pH value is adjusted to 6-8, and the sample is mixed with the molecular clamp.

4. The detection method according to claim 3, characterized in that: and (4) digesting by using acid.

5. The detection method according to claim 1, characterized in that: the detection is selected from the group consisting of visual detection, fluorescence detection, and ultraviolet detection.

6. The detection method according to claim 5, characterized in that: and (4) adopting naked eye detection, and when the pretreated sample solution turns red, the sample to be detected contains silver ions.

7. The detection method according to claim 5, characterized in that: ultraviolet light detection is adopted, absorption peaks exist at 235nm and 257nm, and the sample to be detected contains silver ions.

8. The detection method according to claim 5 or 7, characterized in that: and detecting the content of silver ions in the sample to be detected by adopting ultraviolet light, and determining the absorbance value at 257nm for quantification.

9. The detection method according to claim 5, characterized in that: fluorescence detection is adopted, molecular tweezers are used as a reference, the fluorescence intensity at 268nm is obviously enhanced, and the sample to be detected contains silver ions.

10. The detection method according to claim 1, characterized in that: the sample to be detected is selected from food, medicine and health care product.

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