CN112920189B

CN112920189B - High-sensitivity mercury ion fluorescent sensing material, preparation method and application thereof, and method for detecting concentration of mercury ions in solution

Info

Publication number: CN112920189B
Application number: CN202110127806.7A
Authority: CN
Inventors: 王佳妮; 张娴; 张晗; 张子兴; 崔丽
Original assignee: Institute of Urban Environment of CAS
Current assignee: Institute of Urban Environment of CAS
Priority date: 2021-01-29
Filing date: 2021-01-29
Publication date: 2021-12-21
Anticipated expiration: 2041-01-29
Also published as: CN112920189A

Abstract

The invention belongs to Hg²⁺The field of concentration detection, in particular to a novel supramolecular fluorescent sensing material with double signal amplification functions, a preparation method and application thereof, and application of the fluorescent sensing material in Hg²⁺And (3) a concentration detection method. The fluorescent sensing material has a structure shown in a formula (1), wherein M in the formula (1) is K or Na. In the invention, a catalytic unit is grafted on the barbital, and when a target Hg is obtained²⁺The catalytic units can be orderly gathered, the catalyst enables the substrate to generate fluorescence derivatization reaction, and the oligomerization activity amplification effect of the catalyst is utilized to obviously enhance the fluorescence signal, so that the purpose of fluorescence sensing is achieved. The fluorescence amplification sensor provided by the invention is a signal amplification type fluorescence sensor, and is a novel Hg²⁺The fluorescent sensing mode can compensate the existing Hg based on thymine T²⁺The fluorescent sensing system only adopts colorimetric or fluorescent quenching signals for sensing.

Description

High-sensitivity mercury ion fluorescent sensing material, preparation method and application thereof, and method for detecting concentration of mercury ions in solution

Technical Field

The invention belongs to Hg²⁺The field of concentration detection, in particular to a deviceNovel supramolecular fluorescence sensing material with double signal amplification functions, preparation method and application thereof, and application of fluorescence sensing material in Hg²⁺And (3) a concentration detection method.

Background

The serious physiological toxicity of mercury has long been known. Mercury exists mainly in the forms of metallic mercury, inorganic mercury (mercury salts) and organic mercury, and different kinds of mercury and mercurides can accumulate at different parts after entering a human body, so that the parts are damaged. It is noted that metallic mercury and inorganic mercury are mostly discharged into human body, while organic mercury has strong lipophilicity and is easily enriched in human body, and the "water guarantee" is an example of methyl mercury poisoning. Due to the unique physicochemical properties of mercury, about three thousand industrial production needs to use mercury as raw material or auxiliary material in the world, a large amount of mercury-containing waste water is discharged into the nature at every moment, and the mercury is converted into highly toxic organic mercury by organisms under specific conditions, thus threatening human beings, animals and plants. As mercury ions have easy migration, durability, high biological absorptivity and enrichment, the detection of the mercury ions is concerned, and as mercury has harmful effects on organisms, the sensitive detection of mercury is continuously concerned by the environment and the biological field as an important subject, and the development of a mercury ion detection method with high selectivity, high sensitivity, simplicity and convenience is of great practical significance. Fluorescence has the advantages of simple and convenient operation and control, high sensitivity, small damage to living bodies, real-time detection, remote signal transmission and the like as a detection signal, so that the design of a transition metal ion fluorescent molecular sensing system suitable for monitoring a microsystem is concerned in recent years. Many cases of mercury ion fluorescence sensing systems have been reported, but it is still challenging to obtain a mercury ion fluorescence sensor with high specificity and easy availability.

Thymine T can be mixed with Hg²⁺The reaction, since such a reaction of the T-Hg-T type has a high selectivity and a large binding stability constant, has been widely used for Hg in recent years²⁺In the sensing of (1). At present, based on the T-Hg-T modelHg²⁺The optical sensing of (2) is mainly a colorimetric method and a fluorescence method. In the colorimetric method, nanogold is mostly used as a signal unit, and sensing is performed by utilizing the aggregation discoloration effect of the nanogold, for example: mirkin et al modify an oligodeoxynucleotide chain (ODN) containing thymine on the surface of nanogold when Hg is present²⁺When present, due to Hg²⁺The Hg-T cross-linking structure is formed by the reaction with thymine on the surface of different nano-gold, so that the distance between the nano-gold is shortened, the color of the system is obviously changed, and Hg is realized according to the method²⁺High selectivity, high sensitivity detection (J.S.Lee, M.S.Han and C.A.Mirkin.Angew.chem.Int.Ed.,2007,46, 4093-. Since the T-Hg-T binding reaction corresponds to a base mismatch

Can be used for Hg correction by molecular beacon-like method²⁺Fluorescence sensing of (2). Togashi et al introduced fluorescein as a fluorophore at one end of a specifically designed ODN and a quenching group, Hg, at the other end²⁺The occurrence of the fluorescent dye results in that the ODN forms a hairpin structure due to T-Hg-T reaction, the fluorophore and the quenching group are close to each other to generate energy transfer, and the fluorescence quenching method is utilized to realize Hg²⁺(A.Ono and H.Togashi.Angew.chem.int.Ed.,2004,43, 4300-. Lu et al use the reverse design mode, graft the fluorescence quenching group on one end of ODN, another one end of ODN mated with it grafts the fluorophore, after two ODN hybridize, the fluorophore and quenching group are close to and take place the fluorescence quenching; hg is a mercury vapor²⁺After the addition, a T-Hg-T structure is formed inside the ODN grafted with the fluorophore, so that the T-Hg-T structure is separated from the ODN with the quenching group, and the fluorescence rises back, thereby realizing Hg²⁺OFF-ON light sensing (j.liu and y.lu.angelw.chem.int.ed, 2007,46, 7587-.

Hg of the T-Hg-T type recognition pattern reported at present²⁺The optical sensing systems all show extremely high recognition specificity, but the detection sensitivity of the optical sensing systems still cannot completely meet the requirement of high-toxicity Hg²⁺The need for ion detection. At thymine T receptor pair Hg²⁺On the basis of the high-selectivity and high-affinity bonding effect, a new signal response mode is developed, and Hg is innovated²⁺The sensing of the fluorescence is carried out,establishment of high Performance Hg²⁺Fluorescence detection methods have been the focus of attention in the art.

Disclosure of Invention

The invention aims to provide a novel supramolecular fluorescent sensing material with double signal amplification functions, a preparation method and application thereof, and application of the fluorescent sensing material in high-sensitivity Hg²⁺And (3) a detection method. The Hg is²⁺The fluorescence detection method has the advantages of recognition specificity, ultrahigh sensitivity, convenient operation and low operation cost, and can make up for the existing specific Hg²⁺The optical detection method has the limitations of insufficient sensitivity or complicated operation.

The inventors of the present invention have found, after intensive studies, that a barbiturate derivative having a double imide structure is introduced into Hg²⁺In identification, a catalyst is grafted to a barbiturate side chain in a self-assembly mode when Hg is used²⁺When present, Hg²⁺The chain coordination polymer can be formed with barbital grafted with a catalyst on a side chain, ordered aggregation of catalytic units can be caused after the chain coordination polymer is formed, the catalytic fluorogenic reaction of a substrate is coupled by utilizing the oligomerization activity amplification effect of the catalyst, so that the fluorescent response signal is enhanced rapidly, and the fluorescence in Hg is amplified²⁺The fluorescence enhancement response is obvious when the concentration is only 10nmol/L, and the response is along with Hg²⁺The concentration is increased, the fluorescence signal is further enhanced, and the signal amplification type Hg is realized²⁺And (4) fluorescence sensing. That is, Hg is utilized in the sensing process²⁺The specific recognition is realized by the specific reaction with the imide, the reaction efficiency is effectively improved by utilizing the formation of the coordination polymer, and the dual signal amplification (the coupling of the catalytic amplification effect and the aggregation effect) is carried out by utilizing the ordered aggregation of the catalyst, so that the purposes of ultrahigh selectivity and ultrahigh sensitivity fluorescence sensing are achieved, and the specific principle is shown in a reaction formula (1). Based on this, the present invention has been completed.

Specifically, the invention provides a fluorescence sensing material, wherein the fluorescence sensing material has a structure shown in formula (1):

in the formula (1), M is K or Na.

The invention also provides a preparation method of the fluorescence sensing material, wherein the method comprises the following steps:

s1, synthesis of tetraphenyl sulfonic acid porphyrin iron FeTPPS: dissolving tetraphenyl sulfoporphyrin in water, adjusting the pH value of the obtained tetraphenyl sulfoporphyrin aqueous solution to be neutral by adopting alkaline potassium salt and/or alkaline sodium salt, heating to 80-95 ℃, adding excessive ferrous salt to perform stirring reflux reaction, removing unreacted ferrous salt in the obtained reaction product, adjusting the pH value to be neutral, and then sequentially removing, purifying and drying a solvent to obtain tetraphenyl sulfoporphyrin iron FeTPPS;

s2, synthesis of barbituric acid pyridine PyD: under the protection of inert gas, carrying out reflux reaction on barbituric acid and 4-pyridine formaldehyde in an organic solvent by taking piperidine as a catalyst to obtain barbituric acid pyridine PyD;

s3, synthesis of a high-sensitivity mercury ion fluorescence sensing material FeTPPS-PyD: uniformly mixing tetraphenyl sulfonic acid porphyrin iron FeTPPS and barbituric acid pyridine PyD according to a molar ratio (0.9-1.1): 1, and standing at room temperature to obtain the high-sensitivity mercury ion fluorescent sensing material FeTPPS-PyD.

In a preferred embodiment, in step S1, the molar ratio of the tetraphenylporphyrin to the divalent iron salt is 1 (6 to 7), and may be, for example, 1:6.1, 1:6.2, 1:6.3, 1:6.4, 1:6.5, 1:6.6, 1:6.7, 1:6.8, 1:6.9, 1:7.0, or the like.

In a preferred embodiment, in step S1, the ferrous salt is at least one selected from ferrous sulfate, ferrous chloride and ferrous nitrate.

In a preferred embodiment, in step S1, the alkali potassium salt is KOH and/or K₂CO₃。

In a preferred embodiment, in step S1, step SThe alkaline sodium salt is NaOH and/or Na₂CO₃。

In a preferred embodiment, in step S1, the rotation speed of the stirring reflux reaction is 400 to 600r/min, and the time is 10 to 12 hours.

In a preferred embodiment, in step S1, the unreacted ferrous salt in the reaction product is removed by adjusting the pH of the reaction product to 2 to 4 and then passing through a strong acid type cation exchange resin. The reactive group of the strong acid type cation exchange resin is preferably a sulfonic acid group.

In a preferred embodiment, in step S1, the alcohol solution is first dissolved in methanol, and then the alcohol solution is filtered through a cotton-plug funnel, and the above steps are repeated 2-5 times. The main purpose of the purification is to remove metal salts.

In a preferred embodiment, in step S2, the molar ratio of barbituric acid to 4-pyridinecarboxaldehyde is (0.9-1.1): 1, for example, 0.9:1, 1.0:1, 1.1:1, and most preferably 1: 1.

In a preferred embodiment, the amount ratio of barbituric acid to piperidine used in step S2 is (2 to 3) mmol:1mL, and may be, for example, 2.0mmol:1mL, 2.1mmol:1mL, 2.2mmol:1mL, 2.3mmol:1mL, 2.4mmol:1mL, 2.5mmol:1mL, 2.6mmol:1mL, 2.7mmol:1mL, 2.8mmol:1mL, 2.9mmol:1mL, 3.0mmol:1mL, or the like.

In a preferred embodiment, in step S2, the time of the reflux reaction is 5 to 10 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, and the like.

In a preferred embodiment, in step S3, the standing time is 20 to 30 min.

The invention also provides the application of the high-sensitivity mercury ion fluorescent sensing material in detecting Hg in a solution²⁺Application to concentration.

In addition, the invention also provides a method for detecting Hg in the solution²⁺A concentration method, wherein the method adopts the high-sensitivity mercury ion fluorescent sensing material for detection and comprises the specific detection steps of adding p-hydroxyphenylacetic acid and hydrogen peroxide into Hg-containing²⁺To be treatedDetecting the mercury ion in the solution, and then placing the high-sensitivity mercury ion fluorescent sensing material in the Hg-containing solution²⁺Detecting Hg in the solution to be detected²⁺And (4) concentration.

In a preferred embodiment, the molar ratio of the hydroxyphenylacetic acid to the hydrogen peroxide is (2-100): 1.

In a preferred embodiment, the hydrogen peroxide is used in an amount such that it contains Hg²⁺The concentration in the solution to be detected is 1.00X 10^-6mol/L～1.00×10^-4mol/L。

In a preferred embodiment, the high-sensitivity mercury ion fluorescence sensing material contains Hg²⁺The Hg is detected after the solution to be detected is placed for 200 s-5 min²⁺And (4) concentration.

In a preferred embodiment, the present invention provides for the detection of Hg in a solution²⁺The method of concentration further comprises detecting Hg²⁺Before concentration, the Hg content is²⁺The pH value of the solution to be detected is adjusted to 10-12.

In the invention, a catalytic unit is grafted on the barbital, and when a target Hg is obtained²⁺The catalytic units can be orderly gathered, the catalyst enables the substrate to generate fluorescence derivatization reaction, and the oligomerization activity amplification effect of the catalyst is utilized to obviously enhance the fluorescence signal, so that the purpose of fluorescence sensing is achieved. The fluorescence amplification sensing material provided by the invention is a signal amplification type fluorescence sensing material, and is a novel Hg²⁺The fluorescent sensing mode can compensate the existing Hg based on thymine T²⁺The fluorescent sensing system only adopts colorimetric or fluorescent quenching signals for sensing.

Drawings

FIG. 1 is a graph showing an ultraviolet absorption spectrum of FeTPPS synthesized in example;

FIG. 2 is a MALDI-TOF-MS spectrum of FeTPPS-PyD synthesized in example;

FIG. 3 is a graph of the UV absorption spectrum of the FeTPPS solution of the example after adding PyD with equal concentration;

FIG. 4 shows the reaction system of p-hydroxyphenylacetic acid, hydrogen peroxide and FeTPPS-PyD in different Hg²⁺Fluorescence spectra at concentration;

FIG. 5 shows FeTPPS-PyD and Hg²⁺MALDI-TOF mass spectrum of the bound product;

FIG. 6 is Hg²⁺MALDI-TOF mass spectrum of the binding product with PyD at a molar ratio of 1: 1;

FIG. 7 is a graph showing the change of fluorescence spectra with time of a reaction system of p-hydroxyphenylacetic acid, hydrogen peroxide and FeTPPS-PyD;

FIG. 8 is a graph showing the change of the fluorescence spectrum of p-hydroxyphenylacetic acid, hydrogen peroxide and FeTPPS-PyD with pH.

Detailed Description

The present invention will be described in detail below by way of examples. The examples of embodiments are intended to be illustrative of the invention and are not to be construed as limiting the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

The reagents and equipment used in the following examples are as follows:

(1) the main reagents are as follows: 4-pyridylaldehyde, Tetraphenylporphyrin (TPPS) and p-hydroxyphenylacetic acid are purchased from Bailingwei science and technology Limited, cation exchange resin and hydrogen peroxide are purchased from Shantou Wen Longhua chemical plant Limited, mercuric chloride is purchased from copper mercy chemical reagent factory in Guizhou province, and barbituric acid, ferrous sulfate, sulfuric acid, sodium hydroxide and methanol are all analytically pure and are purchased from national medicine group chemical reagent Limited.

(2) The main apparatus is as follows: hitachi F-7000 type fluorescence spectrophotometer; hitachi U-3900 uv-visible spectrophotometer; bruker AV 400MHz nuclear magnetic resonance instrument; a Micromass-LCT high resolution mass spectrometer; bruker MALDI-TOF mass spectrometer.

Example Synthesis and characterization of high-sensitivity Mercury ion fluorescent sensing Material

(1) Synthesis of FeTPPS

Dissolving tetraphenylporphyrin TPPS (0.2mmol, 200mg) in water (10mL), adjusting pH to neutral with NaOH (0.2mol/L), heating to 90 deg.C, and adding newly-formulated FeSO₄20mL of an aqueous solution (1.3mmol, 358mg) was stirred and refluxed. Tracking the reaction by ultraviolet absorption spectrum until the absorption peak (lambda is 435nm, 645nm) of tetraphenyl sulfoporphyrin TPPS completely disappears, the absorption peak (lambda is 395nm, 528nm) of tetraphenyl sulfoporphyrin iron FeTPPS appears, stopping the reaction, cooling, and reacting with H₂SO₄(0.2mol/L) to adjust the pH to 3.0. The reaction product is passed through strong acid type cation exchange resin to remove excessive Fe²⁺The fractions were quickly pH-adjusted to neutrality with NaOH (0.2 mol/L). The solvent was removed by rotary evaporation, dissolved in methanol (30mL) and filtered through a cotton-stoppered funnel; repeating the above steps for three times to remove Na₂SO₄Finally, the solvent was removed by rotary evaporation, dried in vacuo and the iron tetraphenylporphyrin FeTPPS product (105mg) was weighed out in 45.6% yield.

Ultraviolet absorption spectrum (1.0X 10) of the tetraphenylporphyrin iron FeTPPS^-5mol/L) As shown in FIG. 1, it can be seen from the results of FIG. 1 that characteristic absorption peaks appear at 395nm and 528nm for iron tetraphenylporphyrin FeTPPS, and that characteristic absorption peaks at 435nm and 645nm for the starting material tetraphenylporphyrin TPPS disappear, indicating that the reaction shown in formula (1) has been completed.

(2) Synthesis of pyridine barbiturate PyD

Barbituric acid (5.0mmol, 820mg) was dissolved in methanol (30mL), 4-pyridinecarboxaldehyde (5.0mmol, 0.477mL) and piperidine (2mL) were added, and the reaction was refluxed under nitrogen. Changing the reaction liquid from light yellow to red after 1h and separating out a precipitate, changing the reaction liquid to yellow brown after 3h, tracking the reaction by adopting thin layer chromatography, stopping the reaction after 5h of reaction, obtaining a white precipitate, and obtaining a deep red supernatant. The precipitate was collected by suction filtration and dried under vacuum, and the resulting product was washed with methanol (30mL) three times to remove the residual reactant and dried under vacuum to obtain white powder which was barbituric acid pyridine PyD in a weight of 392mg and a yield of 36%. The reaction process is shown as the formula (2).

Pyridine barbiturate PyD through¹H NMR spectrum,¹³And (3) carrying out structural identification by using spectral means such as C NMR spectrum and ESI-MS, and the like, wherein the related data are as follows:

1H NMR(400MHz,DMSO-d₆,ppm)：δ＝9.62(s,2H),8.54(d,2H，J＝4.0Hz),7.59(d,2H,J＝4.0Hz),5.27(s,1H)。

¹³C-NMR(100MHz,D₂O,ppm)：δ＝165.66,153.28,126.21,88.76,44.52,22.18,21.46。

ESI-MS: [ M + H ] + calculated value 218.1, actual value 218.2.

(3) Synthesis of high-sensitivity mercury ion fluorescent sensing material FeTPPS-PyD

Mixing the aqueous solution of tetraphenyl sulfo porphyrin iron FeTPPS and the aqueous solution of barbituric acid pyridine PyD uniformly according to the molar ratio of 1:1, and standing for 25min at room temperature. The nitrogen atom of pyridine in the barbituric acid pyridine PyD can be axially coordinated with the metal center of tetraphenyl sulfonic porphyrin iron FeTPPS to form the high-sensitivity mercury ion fluorescent sensing material FeTPPS-PyD, and the reaction process is shown as a formula (3).

The formation of the supramolecular structure was confirmed by MALDI-TOF-MS and the results are shown in FIG. 2. As can be seen from FIG. 2, in a solution of tetraphenylporphyrin iron FeTPPS (1.0X 10)^-5mol/L) was added with an equal concentration of pyridine barbiturate PyD (1.0X 10)^-5mol/L), a molecular ion peak of FeTPPS-PyD appears at a mass-to-charge ratio (m/z) of 1293.96; in the process, the ultraviolet absorption spectrum of the system is not obviously changed, and the detail is shown in figure 3.

Test example

(1)Hg²⁺Effect on catalytic efficiency of FeTPPS-PyD

Fixing the concentration of a high-sensitivity mercury ion fluorescence sensing material FeTPPS-PyD, and adding Hg with different concentrations²⁺The influence of the catalytic effect of the catalyst on the reaction system of oxidizing p-hydroxyphenylacetic acid (p-PHA) by hydrogen peroxide is examined, the specific reaction process is shown as formula (4), and FeTPPS-PyD is a catalyst and a mercury ion sensing material in the reaction system. Investigation of p-PHA (5.00X 10)^-4mol/L)、H₂O₂(1.00×10^-4mol/L) and FeTPPS-PyD (1.00X 10)^-7mol/L) in different Hg²⁺Fluorescence spectrum of reaction system with concentration of 0.02mol/L NH₄Cl-NH₃The pH of the solution was adjusted to 11, and all spectra were measured after 5min reaction at room temperature (λ ex ═ 316nm), and the results are shown in fig. 4. As can be seen from fig. 4: no Hg is present²⁺When the catalyst exists, FeTPPS-PyD has catalytic effect on the reaction of oxidizing p-hydroxyphenylacetic acid (p-PHA) by hydrogen peroxide; with Hg²⁺The catalytic activity of the product is obviously enhanced when the concentration is increased, and the characteristic fluorescence emission of the product is gradually enhanced. Hg is a mercury vapor²⁺The catalyst efficiency of FeTPPS-PyD can be improved mainly due to Hg²⁺After the ion-induced coordination polymer is formed, the ordered aggregation of FeTPPS is caused, the local concentration of the catalyst is promoted to be effectively improved, the amplification of a fluorescence signal is generated, and 10nmol/L Hg is added²⁺A significant enhancement of the fluorescence signal has been enabled.

(2)Hg²⁺Discussion of recognition mechanism

As has been elucidated hereinbefore, Hg is due to the fact that barbiturate contains two imide recognition sites²⁺Form a 1:1 coordination polymer with barbiturate derivatives. When Hg is present in the system after FeTPPS-PyD is formed²When the catalyst system is used in the method, + formation of a chain polymer induces ordered aggregation of catalytic unit FeTPPS (see formula (5)), resulting in effective improvement of catalytic efficiency. To confirm formation of coordination polymer, FeTPPS-PyD was investigated with Hg²⁺MALDI-TOF mass spectrum of the bound product, obtainedThe results are shown in FIG. 5. As can be seen in FIG. 5, a set of consecutive metal complex peaks with characteristic spacing appears in the spectra, strongly confirming coordination polymer formation. Their mass to charge ratios (m/z) are 6491, 7569, 8652, 9728, 10800, 11875, 12947, 14002, 15067 and 16148 respectively, i.e. adjacent peak separations differ by 1078, 1083, 1076, 1072, 1075, 1072, 1055, 1065 and 1081 respectively, the average mass to charge ratio (m/z) is 1073, while the molecular weight of FeTPPS is 1075, indicating that coordination bonds between FeTPPS and PyD are susceptible to disruption during mass spectrometry.

In addition, Hg was also examined²⁺MALDI-TOF mass spectrum of the bound product at a 1:1 molar ratio with PyD, as shown in FIG. 6, also shows a set of mass peaks with typical characteristics of polymers, further confirming the formation of Hg (II) -barbiturate coordination polymers.

(3) Investigation of experimental conditions

Selection of catalytic time

In general, the concentration of catalyst and reactants has a significant effect on the equilibration time for a catalyzed reaction. The dynamic process of FeTPPS-PyD catalyzing the reaction of oxidizing p-hydroxyphenylacetic acid by hydrogen peroxide under a series of different catalyst concentrations and different reactant concentrations, namely p-PHA and H, is examined₂O₂And FeTPPS-PyD with 0.02mol/L NH₄Cl-NH₃The change over time of the fluorescence spectrum (. lamda.ex/. lamda.em.: 316nm/404nm) of the reaction system with pH 11 adjusted in the solution is shown in FIG. 7, in which [ H ] in (A) ]₂O₂]＝1.00×10^-6mol/L，[p-HPA]＝1.00×10^-4mol/L，[FeTPPS-PyD]＝1.00×10^- ⁷mol/L; (B) in (H)₂O₂]＝1.00×10^-6mol/L，[p-HPA]＝1.00×10^-4mol/L，[FeTPPS-PyD]＝1.00×10^-6mol/L; (C) in (H)₂O₂]＝1.00×10^-5mol/L，[p-HPA]＝2.00×10^-4mol/L，[FeTPPS-PyD]＝1.00×10^-6mol/L. As can be seen from FIG. 7, in the present catalytic system, the substrate concentration has little effect on the equilibrium time of the reaction; after the concentration of the catalyst is increased, the balance time is greatly shortened, and the fluorescence intensity of the system after the balance is achieved is greatly enhanced.In order to highlight the effect of the polymerization process on the amplification of the catalytic activity, it is advantageous to use a lower initial concentration of FeTPPS-PyD. In the following experiments, the fixed FeTPPS-PyD concentration was 1.00X 10^-7mol/L. It is worth pointing out that the mercury is exposed to FeTPPS-PyD and Hg²⁺In combination with the limitation of the stability constant, continued reduction of the Hg that would result from its concentration²⁺The binding efficiency is lowered, which is not favorable for the improvement of the detection sensitivity. Meanwhile, in the catalytic system, the formation of the complex polymer only corresponds to the increase of the local concentration of the catalyst and does not increase the total concentration of the catalyst, so Hg can be more prominent before the catalytic reaction reaches the equilibrium²⁺Enhancing effect on catalytic activity. Taking these factors into consideration, the fluorescence detection is preferably selected to be performed at 200s to 5 min.

② acidity of the solution

In enzyme-catalyzed assays, pH has a large impact on the final assay sensitivity: one is the enzyme-catalyzed reaction pH and the other is the pH of the product fluorescence measurement. In general, the enzyme-catalyzed reaction is preferably carried out under optimal pH conditions, and then a buffer solution is added to adjust the pH so that the acidity of the solution is favorable for the measurement of the fluorescence of the product. However, in the present catalytic sensing system, it is not necessary to have the catalytic reaction proceed at its optimal pH; hg at a lower pH for catalytic activity²⁺The addition of the catalyst leads the catalytic activity of FeTPPS-PyD to be improved more obviously, but is beneficial to Hg²⁺High sensitivity detection. In order to avoid inconvenience and operation error caused by multiple pH adjustments, catalytic reaction and fluorescence detection are selected under the favorable pH condition of fluorescence emission of the product. For this reason, the effect of different pH on the fluorescence of the product was investigated. P-PHA (1.00X 10)^-4mol/L)、H₂O₂(1.00×10^-6mol/L) and FeTPPS-PyD (1.00X 10)^-7mol/L) of the reaction system, the change curve of the fluorescence spectrum with pH at room temperature is shown in FIG. 8, and the fluorescence spectrum tests are all measured after adjusting the pH value by using different pH buffer solutions and reacting for 5min (lambda ex/lambda em is 316nm/404 nm). As can be seen from FIG. 8, as the pH of the solution increases, the fluorescence of the product gradually increases and becomes stable after pH 10.0. Therefore, NH with pH 11.0 was chosen for the experiments₄Cl-NH₃And controlling the acidity by a buffer system.

In conclusion, the invention utilizes supermolecule self-assembly reaction to graft the catalyst FeTPPS on the barbital side chain, and establishes the high-sensitivity Hg with the function of catalyzing fluorescence signal amplification by taking the catalyst FeTPPS as a receptor²⁺A sensing system. Mass spectrum investigation shows that Hg²⁺Can induce barbiturate acceptor to form coordination polymer, so as to effectively improve the catalytic activity of the catalytic unit. Except for barbiturate-Hg²⁺In addition to the high selectivity of recognition, the present invention is advantageous in that the catalytic reaction is selective for Hg²⁺Amplification of the fluorescent response signal.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.

Claims

1. A high-sensitivity mercury ion fluorescent sensing material with dual signal amplification is characterized in that the high-sensitivity mercury ion fluorescent sensing material has a structure shown in a formula (1):

in the formula (1), M is K or Na.

2. The method for preparing the high-sensitivity mercury ion fluorescence sensing material as claimed in claim 1, wherein the method comprises the following steps:

s1, synthesis of tetraphenyl sulfonic acid porphyrin iron FeTPPS: dissolving tetraphenyl sulfoporphyrin in water, adjusting the pH value of the obtained tetraphenyl sulfoporphyrin aqueous solution to be neutral by adopting alkaline potassium salt and/or alkaline sodium salt, heating to 80-95 ℃, adding excessive ferrous salt for stirring reflux reaction, removing unreacted ferrous salt in the obtained reaction product, adjusting the pH value to be neutral, and then sequentially removing, purifying and drying a solvent to obtain tetraphenyl sulfoporphyrin iron FeTPPS;

3. The preparation method of the high-sensitivity mercury ion fluorescent sensing material according to claim 2, wherein in step S1, the molar ratio of the tetraphenyl sulfoporphyrin to the ferrous salt is 1 (6-7); the ferrous salt is at least one selected from ferrous sulfate, ferrous chloride and ferrous nitrate; the alkaline potassium salt is KOH and/or K₂CO₃(ii) a The alkaline sodium salt is NaOH and/or Na₂CO₃(ii) a The rotating speed of the stirring reflux reaction is 400-600 r/min, and the time is 10-12 h; the unreacted ferrous salt in the reaction product is removed by adjusting the pH value of the reaction product to 2-4 and then passing through strong acid type cation exchange resin.

4. The method for preparing the high-sensitivity mercury ion fluorescent sensing material as claimed in claim 2, wherein in step S2, the molar ratio of the barbituric acid to the 4-pyridinecarboxaldehyde is (0.9-1.1): 1; the dosage ratio of the barbituric acid to the piperidine is (2-3) mmol:1 mL; the time of the reflux reaction is 5-10 h.

5. The method for preparing the high-sensitivity mercury ion fluorescence sensing material according to claim 2, wherein in the step S3, the standing time is 20-30 min.

6. The high-sensitivity mercury ion fluorescent sensing material as defined in claim 1 for detecting Hg in solution²⁺Application to concentration.

7. Method for detecting Hg in solution²⁺A method for detecting concentration, which comprises using the highly sensitive mercury ion fluorescent sensor material according to claim 1 and comprises the step of adding p-hydroxyphenylacetic acid and hydrogen peroxide to the mercury-containing mercury²⁺Then the high-sensitivity mercury ion fluorescent sensing material is placed in the solution to be detected, wherein the solution contains Hg²⁺Detecting Hg in the solution to be detected²⁺And (4) concentration.

8. The method of claim 7 for detecting Hg in a solution²⁺The concentration method is characterized in that the molar ratio of the p-hydroxyphenylacetic acid to the hydrogen peroxide is (2-100): 1; the hydrogen peroxide is used in an amount such that it contains Hg²⁺The concentration in the solution to be detected is 1.00X 10^-6mol/L～1.00×10^-4mol/L。

9. The method of claim 7 for detecting Hg in a solution²⁺The concentration method is characterized in that the high-sensitivity mercury ion fluorescence sensing material contains Hg²⁺The Hg is detected after the solution to be detected is placed for 200 s-5 min²⁺And (4) concentration.

10. The method of claim 7 for detecting Hg in a solution²⁺The method for detecting the concentration is characterized in that the method also comprises the step of detecting Hg²⁺Before concentration, the Hg content is²⁺The pH value of the solution to be detected is adjusted to 10-12.