CN109060733B - Iron ion molecular fluorescence sensor and preparation method thereof - Google Patents

Abstract

The invention provides an iron ion molecular fluorescence sensor and a preparation method thereof. The iron ion molecular fluorescence sensor comprises a transparent resin base layer; a test layer is arranged on one side surface of the transparent resin base layer, and the test layer includes a first gel base material and Fe dispersed in the first gel base material ^{3 +} Molecular fluorescent compound; light-shielding layer, arranged on the surface of the test layer away from the transparent resin base layer, the light-shielding layer includes a second gel base material, a light-shielding filler and an oxidant dispersed in the second gel base material; wherein , the structure of the Fe ³⁺ molecular fluorescent compound is shown in formula I, and Polym is an aminated hydrophilic macromolecular polymer group. The iron ion molecular fluorescence sensor provided by the invention can quickly detect the total concentration of ferrous ions and ferric ions in the liquid to be tested, and has the advantages of high measurement efficiency, high sensitivity, good accuracy, and the like.

Description

Iron ion molecular fluorescence sensor and preparation method thereof

technical field

The invention relates to the technical field of organic synthesis and elemental analysis, in particular to an iron ion molecular fluorescence sensor and a preparation method thereof.

Background technique

Iron is one of the most abundant trace elements in the body. It is an important component of hemoglobin, myoglobin and various enzymes, and participates in processes such as oxygen uptake, oxygen metabolism, and electron transfer. If the body lacks iron, it can affect the synthesis of hemoglobin, and reduce the activity of enzymes such as cytochrome c, ribonucleotide reductase, and succinate dehydrogenase, resulting in serious body dysfunction. The change of Fe ³⁺ content in the human body is related to many diseases, such as iron deficiency can lead to anemia, cancer, diabetes and organ dysfunction, etc., while iron excess can induce Alzheimer's disease, Huntington's disease and Huntington's disease through the generation of reactive oxygen species through the Fenton reaction. disease and Parkinson's disease. Therefore, rapid and accurate detection of iron ion content in the environment and in the human body is of great significance for environmental safety and human health.

At present, there are many analytical techniques for detecting trace amounts of Fe ³⁺ , including atomic absorption spectrometry, plasma emission spectrometry, plasma mass spectrometry, electrochemical methods, and titration methods. Most of these methods require the use of expensive large-scale instruments, which are complicated to operate, poor in portability, and not suitable for online real-time monitoring. Due to the simple equipment required by the fluorescence analysis method, and the advantages of fast response, high sensitivity, and easy operation, the use of fluorescent probes to qualitatively and quantitatively detect Fe ³⁺ has become a research hotspot.

In recent years, there have been few reports on the study of Fe ³⁺ fluorescent probes. Most of them are iron ion fluorescent probes with rhodamine as the fluorescent group, such as Chinese patents CN107011351A, CN 105884788A, Synthesis and evaluation of a novel rhodamine B-based'off-on'fluorescent chemosensor for the selective determination of Fe ³⁺ ions , Sensors and Actuators B: Chemicals, 2017, 242, 921-931. The detection principle of rhodamine-based fluorescent probes is: through the interaction with metal ions, the ring-opening of the self-lactam spiro ring structure can be caused, which can cause changes in ultraviolet-visible absorption and fluorescence spectra, and finally achieve the purpose of detecting the concentration of different metal ions.

However, since rhodamine will participate in the ion coupling reaction, its excitation wavelength and emission wavelength will change due to changes in the detected ions, resulting in the rhodamine-based fluorescence sensor for a variety of different ions cannot be detected with the same excitation and emission wavelength. Moreover, the excitation wavelength of the Fe ³⁺ fluorescence sensor reported above is about 560nm, the emission wavelength is about 580nm, and its Stokes shift is only about 20nm. It is difficult for ordinary optical spectroscopic lenses to distinguish the excitation light from the fluorescence, thus affecting the detection results. Generally, a spectral detection device with high spectral resolution is used for fluorescence signal collection, and the difficulty and cost of detection will be greatly increased.

In addition to the above problems, some existing liquid environments contain both ferrous ions and ferric ions, and it is often necessary to detect the total concentration of ferric ions and ferric ions during detection. However, the current Fe ³⁺ molecular fluorescence sensor cannot detect the ferrous ions in it, and some spectrophotometric methods for the detection of the total iron content in the solution are mostly based on first reducing Fe ³⁺ to Fe ²⁺ with the reducing agent hydroxylamine hydrochloride. After 10 minutes of stabilization, Fe ²⁺ is measured again, which takes a long time and has low sensitivity.

Based on the above reasons, it is very necessary to provide a fluorescent sensor that can detect the total concentration of ferrous ions and ferric ions, and can quickly detect and measure more sensitive iron ions.

Contents of the invention

The main purpose of the present invention is to provide a kind of iron ion molecular fluorescence sensor and preparation method thereof, to solve the problem that the Fe3 ⁺ molecular fluorescence sensor in the prior art cannot be quickly measured, the sensitivity is not enough, and it cannot detect ferrous ion and trivalent iron ion simultaneously. The problem of the total concentration of iron ions.

In order to achieve the above object, according to one aspect of the present invention, a kind of iron ion molecular fluorescence sensor is provided, which includes a transparent resin base layer; the test layer is arranged on one side surface of the transparent resin base layer, and the test layer includes a first gel Adhesive substrate and dispersed in the first gel substrate ^Fe Molecular fluorescent compound; Light-shielding layer, arranged on the surface of the test layer away from the transparent resin base layer side, the light-shielding layer includes the second gel substrate, A light-shielding filler and an oxidizing agent dispersed in the second gel substrate; wherein, the Fe ³⁺ molecular fluorescent compound has a structure shown in formula I:

In formula I, Polym is an aminated hydrophilic macromolecular polymer group.

Further, Polym is the residue formed by the dehydrogenation of aminocellulose, the residue formed by the dehydrogenation of aminomaltodextrin or the residue formed by the dehydrogenation of aminovinylpyrrolidone; preferably aminocellulose is aminoethylcellulose, aminohydroxyl One or more of ethyl cellulose, aminohydroxypropyl cellulose and aminocarboxymethyl cellulose.

Further, the oxidant is one or more of potassium permanganate, ceric sulfate and sodium bismuthate.

Further, the light-shielding filler is carbon black.

Further, the first gel substrate and the second gel substrate are respectively selected from one or more of D4 hydrogel, D6 hydrogel, acrylamide-acrylonitrile copolymer and polyvinyl alcohol.

Further, the material of the transparent resin base layer is one or more of PET, PMMA, PC, PVC, PS, PP and ABS.

According to another aspect of the present invention, there is also provided a method for preparing an iron ion molecular fluorescence sensor, which includes the following steps: step L1, providing a transparent resin base layer; step L2, adding Fe3 ⁺ molecular fluorescent compound, the first condensation The gel material of the adhesive substrate and the first gel solvent are mixed, the obtained mixture is coated on one side surface of the transparent resin base layer, and the test layer is formed after drying; step L3, the light-shielding filler, the oxidizing agent, the second gel The gel material of the adhesive base material is mixed with the second gel solvent, and the obtained mixture is coated on the surface of the test layer on the side away from the transparent resin base layer, and dried to form a light-shielding layer, thereby obtaining an iron ion molecular fluorescence sensor; wherein , the Fe ³⁺ molecular fluorescent compound has a structure shown in formula I:

In formula I, Polym is an aminated hydrophilic macromolecular polymer group.

Further, the Fe ³⁺ molecular fluorescent compound is prepared by the following method:

In step S1, compound A and compound B are condensed to form compound C; the structures of compound A, compound B and compound C are as follows, wherein X in compound A is a halogen:

In step S2, compound C is hydrolyzed to obtain compound D; the structure of compound D is as follows:

Step S3, performing a condensation amidation reaction between the compound D and the aminated hydrophilic macromolecular polymer to obtain a fluorescent compound of Fe ³⁺ molecules.

Further, the aminated hydrophilic macromolecular polymer is aminocellulose, aminomaltodextrin or aminopolyvinylpyrrolidone; preferably, before step S1, the preparation method also includes the step of preparing compound A, which includes: 4-cyanobenzoic acid and tert-butanol carry out esterification reaction to obtain tert-butyl 4-cyanobenzoate; mix tert-butyl 4-cyanobenzoate, catalyst and methanol to form a mixed system, and pass through the mixed system Go into hydrogen and carry out hydrogenation reaction, obtain 4-aminomethylbenzoic acid tert-butyl ester E; Wherein catalyzer is one or more in nickel catalyst, palladium carbon catalyst and cobalt catalyst; 4-aminomethylbenzoic acid tert-butyl ester E reacts with compound F to obtain compound A; wherein tert-butyl 4-aminomethylbenzoate E and compound F have the following structures:

Wherein X in compound F is halogen.

Further, step S1 includes: mixing compound A, compound B and an acid-binding agent with a first solvent to obtain a first mixture; performing a condensation reaction on the first mixture at a temperature of 80-100° C. to obtain a first product system; The first product system is cooled and poured into water, filtered to obtain a precipitate, which is compound C; preferably, the first solvent is N-methylpyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, dimethyl One or more of acetamide and tetrahydrofuran; preferably, the acid-binding agent is N,N-diisopropylethylamine, N,N-dimethylformamide, 4-dimethylaminopyridine and triethyl One or more of the amines; preferably, the molar ratio between compound A, compound B and the acid-binding agent is 1 to 6:1 to 5:1 to 15; preferably, after the filtering step, step S1 also Including the step of washing the precipitate, the washing step includes: dissolving the precipitate in chloroform, adding water to it for washing, separating the liquids to obtain an organic phase and an aqueous phase; drying the organic phase with anhydrous sodium sulfate, filtering and evaporating , to obtain compound C.

Further, step S2 includes: mixing and reacting compound C, a carbonyl removing reagent and a second solvent to obtain a second product system; diluting the second product system with a chloroform/methanol mixed solution with a volume ratio of 1:1, Then the solvent is evaporated to obtain compound D; preferably, the carbonyl removal reagent is trifluoroacetic acid, a mixed reagent of hydrochloric acid and ethyl acetate with a volume ratio of 1:2, or silica gel; preferably, the second solvent is dichloromethane and/or or chloroform; preferably, the molar amount of compound C is 1.8-2.0%, preferably 1.9%, of the molar amount of the carbonyl-removing reagent.

Further, step S3 includes: mixing and reacting compound D, aminated hydrophilic macromolecular polymer, dehydrating agent, carbonyl activator and a third solvent to obtain a third product system; filtering the third product system, and Wash and dry the filtered precipitate to obtain Fe ³⁺ molecule fluorescent compound; preferably, the dehydrating agent is N,N-dicyclohexyl-1,3-carbodiimide, 1-(3-dimethylaminopropane one or more of -3-ethylcarbodiimide hydrochloride and diisopropylcarbodiimide; preferably, the carbonyl activator is N-hydroxysuccinimide and/or N- Hydroxysulfosuccinimide; preferably, the third solvent is N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide and hexamethylphosphoryl One or more of triamines; preferably, the amount of compound D is 2 to 3% of the weight of the aminated hydrophilic macromolecular polymer; preferably, when the aminated hydrophilic macromolecular polymer is polymerized Before the mixture, step S3 also includes: suspending the aminated hydrophilic macromolecular polymer in aqueous sodium carbonate solution, filtering, resuspending in DMF, filtering, and washing with DMF to obtain the pretreated aminated hydrophilic macromolecular polymer. Water-based macromolecular polymer.

Further, the step of carrying out the esterification reaction of 4-cyanobenzoic acid and tert-butanol comprises: mixing and reacting 4-cyanobenzoic acid and the fourth solvent of an acylating agent to obtain an intermediate; removing the solvent in the intermediate Afterwards, it is mixed and reacted with an esterification catalyst and tert-butanol to obtain the fourth product system; the fourth product system is purified to obtain tert-butyl 4-cyanobenzoate; preferably, the acylating agent is oxalyl chloride, chlorine One or more of sulfoxide, phosphorus trichloride and phosphorus pentachloride; preferably, the esterification catalyst is pyridine, N,N-dimethylformamide, 4-dimethylaminopyridine and triethylamine One or more in; Preferably, the molar ratio between 4-cyanobenzoic acid and acylating reagent is 2～3:3～5; The volume ratio between esterification catalyst and tert-butanol is 1～ 1.1:1.

Further, in the step of preparing tert-butyl 4-aminomethylbenzoate E, the weight ratio between tert-butyl 4-cyanobenzoate and the catalyst is 10～20:1～3; 4-cyanobenzoic acid The weight ratio between tert-butyl ester and methanol is 1-3:8-20; preferably, after the hydrogen gas is introduced, the pressure of the reaction system is 0.8-1.2 MPa.

Further, the step of reacting tert-butyl 4-aminomethylbenzoate E with compound F comprises: mixing and reacting tert-butyl 4-aminomethylbenzoate E, compound F and a fifth solvent to obtain the fifth Product system; filter the fifth product system, and dry the obtained precipitate to obtain compound A; preferably, the fifth solvent is one or more of ethanol, methanol, propanol and isopropanol; preferably, 4- The molar ratio between tert-butyl aminomethylbenzoate E and compound F is 1:1.

Further, both the first gel solvent and the second gel solvent are mixed solvents of water and ethanol.

The invention provides an iron ion molecular fluorescence sensor, which includes a transparent resin base layer, a test layer and a light-shielding layer, the test layer is arranged on one side surface of the transparent resin base layer, and the test layer includes a first gel base material and a dispersed ^Fe in the first gel substrate Molecular fluorescent compound; The light-shielding layer is arranged on the surface of the test layer away from the transparent resin base layer side, and the light-shielding layer includes the second gel base material, dispersed in the second gel Opacifying fillers and oxidizing agents in substrates.

First of all, the shading layer of the sensor provided by the present invention contains an oxidizing agent. In the actual detection process, the liquid to be detected first passes through the shading layer and enters the test layer, and the ferrous ions in it can be oxidized to ferric ions by the oxidizing agent. The concentration of ferric ions detected in the layer is actually the total concentration of ferrous ions and ferric ions in the liquid to be tested. At the same time, the light-shielding filler in the light-shielding layer can also serve the purpose of shielding the interference of external light, thereby improving the measurement accuracy of the sensor.

Secondly, the Fe ³⁺ molecular fluorescent compound in the above test layer uses 1,8-naphthalimide as the fluorescent group, which makes it have good photostability, and the excitation (449nm) and emission light (521nm) are both long-wavelength visible light , large Stokes shift (72nm), high quantum yield. At the same time, the Fe ³⁺ molecule in the fluorescent compound The group (test group) has high sensitivity to Fe ³⁺ , and the nitrogen in the pyridine ring and the 4-amino nitrogen can complex with Fe ³⁺ to form an ion complex, which can cause electron transfer or energy transfer , so that the test reagent has different fluorescence responses under different Fe ³⁺ concentrations. In addition, the aminated hydrophilic macromolecular polymer group in the Fe3 ⁺ molecular fluorescent compound can play a role in fixing and dispersing the fluorescent group and the test group, so that the fluorescent group and the test group The test group can be better dispersed, and the aminated hydrophilic macromolecular polymer group itself provides micropores, so that the Fe ³⁺ in the sample to be tested can enter more fully and be more closely related to the test group. Sufficient and faster contact, so that the Fe ³⁺ molecular fluorescent compound provided by the present invention has better test accuracy and sensitivity.

In a word, the above factors make the iron ion molecular fluorescence sensor provided by the present invention capable of quickly detecting the total concentration of ferrous ions and ferric ions in the liquid to be tested, and has the advantages of high measurement efficiency, high sensitivity, and accuracy. Good and other advantages.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 shows the structural representation of the iron ion molecular fluorescence sensor according to the present invention;

Fig. 2 shows the H NMR spectrum of tert-butyl-4-aminomethylpyridine-1,8-naphthalimide methylbenzoate prepared in Example 1 of the present invention;

Fig. 3 shows the H NMR spectrum of 4-aminomethylpyridine-1,8-naphthalimidomethylbenzoic acid prepared in Example 1 of the present invention;

Fig. 4 shows the change diagram of the fluorescence spectrum of the iron ion fluorescent sensor made in Example 1 of the present invention as the concentration of iron ions (Fe ³⁺ :Fe ²⁺ =1:1) increases;

Fig. 5 shows the change diagram of the fluorescence intensity of the iron ion fluorescent sensor prepared in Example 1 of the present invention as the concentration of iron ions (Fe ³⁺ :Fe ²⁺ =1:1) increases;

6 shows a schematic diagram of the fluorescence selective recognition of iron ions by the iron ion (Fe ³⁺ :Fe ²⁺ =1:1) fluorescence sensor prepared in Example 1 of the present invention;

Fig. 7 shows the iron ion (Fe ³⁺ :Fe ²⁺ =1:1) fluorescence sensor prepared in the embodiment 1 of the present invention to detect the anti-interference identification schematic diagram of iron ion;

Fig. 8 shows the fluorescence intensity recognition schematic diagram of the ferric ion fluorescent sensor that makes in the embodiment 1 of the present invention to the ferric ion mixture that contains different concentration ratios Fe3 ⁺ and Fe2 ⁺ There was no significant difference under the least significant difference (LSD) test (P<0.05)].

Wherein, the above-mentioned accompanying drawings include the following reference signs:

10. Transparent resin base layer; 20. Test layer; 30. Shading layer.

Detailed ways

It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and examples.

The present application will be described in further detail below in conjunction with specific examples, and these examples should not be construed as limiting the scope of protection claimed in the present application.

As described in the background technology section, the Fe ³⁺ molecular fluorescence sensor in the prior art cannot be reversibly measured, has insufficient accuracy, and cannot simultaneously detect the total concentration of ferrous ions and ferric ions.

In order to solve the above problems, the present invention provides a kind of iron ion molecular fluorescence sensor, as shown in Figure 1, it comprises transparent resin base layer 10, test layer 20 and light-shielding layer 30; Test layer 20 is arranged on transparent resin base layer 10 On one side surface, test layer 20 comprises the first gel base material and Fe3 ⁺ molecule fluorescent compound dispersed in the first gel base material; Light-shielding layer 30 is arranged on the side of test layer 20 away from transparent resin base layer 10 On the surface, the light-shielding layer 30 includes a second gel base material, a light-shielding filler and an oxidant dispersed in the second gel base material; wherein, the Fe ³⁺ molecular fluorescent compound has a structure shown in formula I:

In formula I, Polym is an aminated hydrophilic macromolecular polymer group.

First of all, the shading layer of the sensor provided by the present invention contains an oxidizing agent. In the actual detection process, the liquid to be detected first passes through the shading layer and enters the test layer, and the ferrous ions in it can be oxidized to ferric ions by the oxidizing agent. The concentration of ferric ions detected in the layer is actually the total concentration of ferrous ions and ferric ions in the liquid to be tested. At the same time, the light-shielding filler in the light-shielding layer can also serve the purpose of shielding the interference of external light, thereby improving the measurement accuracy of the sensor.

Secondly, the Fe ³⁺ molecular fluorescent compound in the above test layer uses 1,8-naphthylimide as the fluorescent group, which makes it have good photostability, and the excitation (449nm) and emission light (521nm) are both long-wavelength visible light , large Stokes shift (72nm), high quantum yield. At the same time, the Fe ³⁺ molecule in the fluorescent compound The group (test group) has high sensitivity to Fe ³⁺ , and the nitrogen in the pyridine ring and the 4-amino nitrogen can complex with Fe ³⁺ to form an ion complex, which can cause electron transfer or energy transfer , so that the test reagent has different fluorescence responses under different Fe ³⁺ concentrations. In addition, the aminated hydrophilic macromolecular polymer group in the Fe3 ⁺ molecular fluorescent compound can play a role in fixing and dispersing the fluorescent group and the test group, so that the fluorescent group and the test group The test group can be better dispersed, and the aminated hydrophilic macromolecular polymer group itself provides micropores, so that Fe ³⁺ in the sample to be tested can enter more fully and be more closely related to the test group. Sufficient and faster contact, so that the Fe ³⁺ molecular fluorescent compound provided by the present invention has better test accuracy and sensitivity.

In short, the above factors make the iron ion molecular fluorescence sensor provided by the present invention capable of detecting the total concentration of ferrous ions and ferric ions in the liquid to be tested, and has the advantages of high measurement efficiency, high sensitivity, and good accuracy. Etc. The linear response range of the sensor to the concentration of Fe ³⁺ is 4-1000 μmol/L, and the detection limit is 1.36 μmol/L.

In addition to the above advantages, none of the dispersion media used in the test layer 20 and the light-shielding layer 30 in the present invention has a gel base material. Compared with other dispersion media, the use of a gel base material can greatly simplify the preparation process. After coating, only It can be molded after drying, without light curing or heat curing procedures, and it is also beneficial to prevent light and heat curing conditions from affecting the stability of the testing machine.

It should be noted that, in the present invention above-mentioned formula I (referred to as functional groups here) and the molar ratio between the Polym hydrophilic macromolecular polymer group is not limited to 1:1, and the loading capacity of the functional group on the hydrophilic macromolecular polymer group is It can be adjusted according to the number of amino functional groups in the corresponding hydrophilic macromolecular polymer, which only means that the functional group and the hydrophilic macromolecular polymer group are connected by chemical bonds.

In a preferred embodiment, the aforementioned Polym includes, but is not limited to, residues formed by dehydrogenation of aminocellulose, residues formed by dehydrogenation of aminomaltodextrin or residues formed by dehydrogenation of aminovinylpyrrolidone. These residues are actually the groups formed after the amino hydrogen atoms are removed from the aminated hydrophilic macromolecular polymer. Preferably, the aminocellulose is one or more of aminoethylcellulose, aminohydroxyethylcellulose, aminohydroxypropylcellulose and aminocarboxymethylcellulose. These macromolecular groups all have good hydrophilicity, and can form a stable chemical connection with the above-mentioned functional groups, and have better dispersion performance for the above-mentioned functional groups, as the carrier of the functional groups can further improve Fe Stability, sensitivity and measurement accuracy of ³⁺ molecular fluorescent compounds. Moreover, these macromolecular groups have good bonding properties with the base layer in the final iron ion molecular fluorescence sensor, which is also conducive to further improving the stability of the product.

In a preferred embodiment, the oxidant is one or more of potassium permanganate, ceric sulfate and sodium bismuthate. These oxidants have strong oxidizing ability and can oxidize ferrous ions more rapidly. The sensor of the present invention is used to test the content of trace iron ^ions in the liquid. The effect of the oxidizing agent is to oxidize the trace Fe in the liquid to be measured to Fe ^3+. The approximate content of ²⁺ should be adjusted, which should be understood by those skilled in the art.

In a preferred embodiment, the opacifying filler is carbon black. Using the above-mentioned light-shielding filler can improve the light-shielding performance of the light-shielding layer 30 , thereby helping to reduce and further reduce the interference of light on fluorescence detection. In actual detection, the weight ratio between the second gel substrate and the light-shielding filler can be adjusted according to the detection environment, which should be understood by those skilled in the art. In order to further reduce the interference of light, on the other hand, the light-shielding layer has a relatively high cohesive force. It is recommended that the weight ratio between the second gel base material and the light-shielding filler of the present invention be 3.2:1.

In a preferred embodiment, the first gel substrate and the second gel substrate are respectively selected from one of D4 hydrogel, D6 hydrogel, acrylamide-acrylonitrile copolymer and polyvinyl alcohol or more. The above-mentioned Fe ³⁺ molecular fluorescent compound provided by the present invention has better compatibility with these several kinds of hydrogels, and the dispersibility of test reagents in them is better. In addition, these hydrogels have better bonding properties with the substrate layer, which is conducive to further improving the stability of the iron ion molecular fluorescence sensor. In addition, the sensor of the present invention is used to test the content of trace iron ions in the liquid, and the weight ratio between the Fe ³⁺ molecule fluorescent compound and the first gel substrate in the test layer 20 can be determined according to the Fe ³⁺ and Fe in the liquid to be tested. The approximate content of ²⁺ should be adjusted, which should be understood by those skilled in the art.

In a preferred embodiment, the material of the transparent resin base layer 10 includes but not limited to one or more of PET, PMMA, PC, PVC, PS, PP and ABS. These resin materials have better transparency, which is beneficial to further improving the accuracy and stability of fluorescence detection.

Preferably, the thickness of the transparent resin base layer 10 is 75-125 μm, the thickness of the test layer 20 is 100-200 μm, and the thickness of the light-shielding layer 30 is 100-200 μm.

According to another aspect of the present invention, there is also provided a method for preparing an iron ion molecular fluorescence sensor, which includes the following steps: step L1, providing a transparent resin base layer; step L2, adding Fe3 ⁺ molecular fluorescent compound, the first condensation The gel material of the adhesive substrate and the first gel solvent are mixed, the obtained mixture is coated on one side surface of the transparent resin base layer, and the test layer is formed after drying; step L3, the light-shielding filler, the oxidizing agent, the second gel The gel material of the adhesive base material is mixed with the second gel solvent, and the obtained mixture is coated on the surface of the test layer on the side away from the transparent resin base layer, and dried to form a light-shielding layer, thereby obtaining an iron ion molecular fluorescence sensor; wherein , the Fe ³⁺ molecular fluorescent compound has a structure shown in formula I:

In formula I, Polym is an aminated hydrophilic macromolecular polymer group.

As mentioned above, whether it is in aqueous solution or human body fluid, the iron ion molecular fluorescence sensor prepared by this preparation method has the advantages of high measurement efficiency, high sensitivity and good accuracy when measuring the concentration of Fe ³⁺ in the sample. It exhibits good analytical characteristics, and its linear response to Fe ³⁺ concentration ranges from 4 to 1000 μM, with a lower detection limit of 1.36 μM. At the same time, the iron ion molecular fluorescence sensor can also detect the total concentration of ferrous ions and ferric ions in the liquid to be tested.

In a preferred embodiment, the above-mentioned Fe3 ⁺ molecular fluorescent compound is prepared by the following method:

In step S1, compound A and compound B are condensed to form compound C; the structures of compound A, compound B and compound C are as follows, wherein X in compound A is a halogen:

In step S2, compound C is hydrolyzed to obtain compound D; the structure of compound D is as follows:

Step S3, performing a condensation amidation reaction between the compound D and the aminated hydrophilic macromolecular polymer to obtain a fluorescent compound of Fe ³⁺ molecules.

The present invention utilizes the condensation reaction of compound A and compound B, the hydrolysis reaction of compound C, the reaction of compound D and aminated hydrophilic macromolecular polymers to synthesize the above-mentioned Fe3 ⁺ molecular fluorescent compound with a shorter route, and The preparation method has simple process operation and mild conditions, and is very suitable for large-scale industrial application.

Preferably, the aminated hydrophilic macromolecular polymer is aminocellulose, aminomaltodextrin or aminopolyvinylpyrrolidone; more preferably aminocellulose is aminoethylcellulose, aminohydroxyethylcellulose, aminohydroxyl One or more of propyl cellulose and amino carboxymethyl cellulose.

The above-mentioned compound A can be selected from commercially available products. In a preferred embodiment, before step S1, the preparation method also includes the step of preparing compound A, which includes: esterifying 4-cyanobenzoic acid and tert-butanol reaction to obtain tert-butyl 4-cyanobenzoate; tert-butyl 4-cyanobenzoate, catalyst (one or more of nickel catalyst, palladium carbon catalyst and cobalt catalyst) and methanol are mixed to form a mixed system , feed hydrogen into the mixed system for hydrogenation reaction to obtain tert-butyl 4-aminomethylbenzoate E; react tert-butyl 4-aminomethylbenzoate E with compound F to obtain compound A; wherein 4- Aminomethylbenzoic acid tert-butyl ester E, compound F have the following structures:

Wherein X in compound F is halogen.

Compound A is prepared by the above method, the route is short, the process is simple, the cost is lower, and the yield is relatively high.

Concrete process conditions in each of the above synthetic steps can be adjusted, specifically as follows:

In a preferred embodiment, the above step S1 includes: mixing compound A, compound B and an acid-binding agent with a first solvent to obtain a first mixture; heating the first mixture at 80-100°C, more preferably at 90°C The condensation reaction is carried out at high temperature to obtain the first product system; the first product system is cooled and poured into water, and filtered to obtain a precipitate, which is compound C.

Preferably, the first solvent includes but not limited to one or more of N-methylpyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, dimethylacetamide and tetrahydrofuran.

Preferably, the acid-binding agent is one or more of N-methylpyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, dimethylacetamide and tetrahydrofuran. The use of these several acid-binding agents is conducive to further improving the reaction efficiency between compound A and compound B, and improving the reaction conversion rate.

Preferably, the molar ratio between compound A, compound B and the acid-binding agent is 1-6:1-5:1-15; preferably, after the filtering step, step S1 also includes the step of washing the precipitate, washing The steps include: dissolving the precipitate in chloroform, adding water to it for washing, and separating the liquids to obtain an organic phase and an aqueous phase; drying the organic phase with anhydrous sodium sulfate, filtering and evaporating to obtain compound C.

An example is as follows: tert-butyl-4-chloro-1,8-naphthalimide methyl benzoate (compound A), 2-aminopicoline (compound B) and N, N-di Isopropylethylamine was suspended in N-methylpyrrolidone (NMP) and heated at 90°C for 18 hours. The mixture is cooled and poured into water. The precipitate was obtained by filtration, then dissolved in CHCl ₃ and washed with water, and the layers were separated. The organic layer was dried _{over Na2SO4} , filtered and evaporated to give the crude product, which was hot slurried with hot methanol at 55-60 °C, filtered and washed with cold methanol at 0-10 °C. The obtained solid (solid after washing with cold methanol) was recrystallized from hot _CHCl3 at 50-55 °C to give yellow crystals of tert-butyl-4-aminomethylpyridine-1,8-naphthalimidomethylbenzene Formate (compound C).

In a preferred embodiment, the above step S2 includes: mixing and reacting compound C, a carbonyl removing reagent and a second solvent to obtain a second product system; using a mixture of chloroform/methanol with a volume ratio of 1:1 The solution dilutes the second product system, and the solvent is evaporated to give compound D. The tert-butoxycarbonyl (BOC) group of reactant C was removed using a carbonyl removing reagent. The mixed solution of chloroform/methanol with a volume ratio of 1:1 can be used as a solvent to dilute the product, thereby removing excess carbonyl-removing reagent.

Preferably, the above-mentioned carbonyl removal reagent is trifluoroacetic acid, a mixed reagent of hydrochloric acid and ethyl acetate with a volume ratio of 1:2, or silica gel. For the purposes of reducing side reactions and simplifying the post-treatment process, trifluoroacetic acid is more preferably used as the carbonyl removal reagent.

Preferably, the second solvent is dichloromethane and/or chloroform, wherein dichloromethane is less toxic and more environmentally friendly. Preferably, the molar amount of compound C is 1.8-2.0%, more preferably 1.9%, of the molar amount of the carbonyl-removing reagent.

An example is as follows: adding trifluoroacetic acid (TFA) to _CH2Cl2 where tert-butyl- ₄ -aminomethylpyridine-1,8-naphthalimidomethylbenzoate (Compound C) in solution. The resulting solution was stirred at room temperature for about 1 hour until thin layer chromatography (TLC) showed that most of tert-butyl-4-aminomethylpyridine-1,8-naphthalimidomethylbenzoate disappeared. The mixture was then diluted with _CHCl3 :MeOH in a volume ratio of 1:1 and the solvent was evaporated. Repeat 4 to 8 times to remove TFA, then place on pump for 30 minutes to dry completely to give yellow crystalline 4-aminomethylpyridine-1,8-naphthalimidomethylbenzoic acid (compound D) .

In a preferred embodiment, the above step S3 includes: mixing and reacting compound D, an aminated hydrophilic macromolecular polymer, a dehydrating agent, a carbonyl activator and a third solvent to obtain a third product system; The third product system is filtered, and the filtered precipitate is washed and dried to obtain Fe ³⁺ molecular fluorescent compound. The use of a carbonyl activator can increase the activation of the carbonyl in compound D, and the addition of a dehydrating agent is beneficial to increase the conversion rate of the reaction. Preferably, the dehydrating agent is N,N-dicyclohexyl-1,3-carbodiimide (DCC), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride One or more of (EDCI) and diisopropylcarbodiimide (DIC); preferably, the carbonyl activator is N-hydroxysuccinimide (NHS) and/or N-hydroxysulfosuccinyl Imine (Sulfo-NHS).

Preferably, the third solvent is N,N-dimethylformamide (DMF), N,N-diethylformamide (DEF), N,N-dimethylacetamide (DMAC) and hexamethylphosphorus One or more in amide triamide (HMPT); Preferably, the consumption of compound D is 2～3% of the weight of the hydrophilic macromolecular polymer of amination (more preferably the weight ratio of the two is 13: 500); Preferably, before the aminated hydrophilic macromolecular polymer is mixed, step S3 also includes: suspending the aminated hydrophilic macromolecular polymer in aqueous sodium carbonate solution, filtering, and resuspending in DMF , filtered, and then washed with DMF to obtain a pretreated aminated hydrophilic macromolecular polymer. Utilize this step to wash the aminated hydrophilic macromolecular polymer and remove the water therein.

An example is as follows: Suspend a hydrophilic macromolecular polymer (such as aminoethyl cellulose) in an aqueous solution of sodium carbonate for 30 minutes, filter, resuspend in DMF for 30 minutes, filter, and wash twice with DMF to replace the retained water . Then, the washed hydrophilic macromolecular polymer is transferred to a compound containing 4-aminomethylpyridine-1,8-naphthalimidomethylbenzoic acid (compound D), N,N-dicyclohexyl-1 , 3-carbodiimide (DCC) and N-hydroxysuccinimide (NHS) were mixed in anhydrous DMF, and the mixed suspension was stirred at room temperature for 20 hours. Then the crude product was obtained by filtration, washed with DMF, water, HCl, water, NaOH, water, acetone, ether, and finally vacuum-dried for 16 hours to obtain a yellow powder, which was the Fe ³⁺ molecular fluorescent compound.

In a preferred embodiment, the step of esterifying 4-cyanobenzoic acid and tert-butanol comprises: mixing and reacting 4-cyanobenzoic acid, an acylating agent and a fourth solvent to obtain an intermediate ; After removing the solvent in the intermediate, mix and react it with the esterification catalyst and tert-butanol mixture to obtain the fourth product system; purify the fourth product system to obtain tert-butyl 4-cyanobenzoate. Utilize an acylating agent to first carry out acylation reaction with 4-cyanobenzoic acid to form an intermediate product, and then react with tert-butyl alcohol under the action of an esterification catalyst to form tert-butyl 4-cyanobenzoate. Compared with the direct reaction between acid and pure, the route provided by the invention is used to prepare tert-butyl 4-cyanobenzoate, and the conversion rate of raw materials is higher. Preferably, the acylating agent is one or more of oxalyl chloride, thionyl chloride, phosphorus trichloride and phosphorus pentachloride; preferably, the esterification catalyst is pyridine, N,N-dimethylformamide One or more of (DMF), 4-dimethylaminopyridine (DMAP) and triethylamine.

Preferably, the molar ratio between 4-cyanobenzoic acid and acylating reagent is 2～3:3～5, more preferably 2:3; The weight of the intermediate of the solvent is denoted as m, m:n is 1～3:10～20, more preferably 3:20; the volume ratio between the esterification catalyst and tert-butanol is 1～1.1:1, preferably 1:1.

An example is as follows: 4-cyanobenzoic acid was dissolved in anhydrous _CH2Cl2 , oxalyl _chloride and dimethylformamide (DMF) were added. The resulting mixture was stirred at room temperature for 1 hour until gas evolution ceased. The solvent was removed and the resulting residue was treated with a pyridine/tert-butanol mixture and stirred at room temperature for 6 hours. The solvent was evaporated under reduced pressure, and the green residue was suspended in water, followed by extraction with ethyl acetate. The combined organic layers were washed, dried _{over Na2SO4} and evaporated. The crude product was purified by an ethyl acetate/petroleum ether column to obtain tert-butyl 4-cyanobenzoate as a white solid.

In a preferred embodiment, in the step of preparing tert-butyl 4-aminomethylbenzoate E, the weight ratio between tert-butyl 4-cyanobenzoate and the catalyst is 10～20:1～3, More preferably 10:1; The weight ratio between tert-butyl 4-cyanobenzoate and methanol is 1～3:8～20, more preferably 3:20; Preferably, after feeding hydrogen, the reaction system The pressure is 0.8-1.2 MPa, more preferably 1 MPa. Utilize above-mentioned technique to prepare tert-butyl 4-aminomethylbenzoate E, the efficiency of reaction is higher, and above-mentioned catalyst can specifically adopt one or more in nickel catalyst, palladium-carbon catalyst and cobalt catalyst.

An example is as follows: tert-butyl 4-cyanobenzoate and nickel catalyst are mixed in methanol and hydrogenated under a pressure of 1 MPa for 16 hours. The catalyst was removed by filtration, and the solvent was removed under reduced pressure to give tert-butyl 4-aminomethylbenzoate as a white solid.

In a preferred embodiment, the step of reacting tert-butyl 4-aminomethylbenzoate E with compound F comprises: mixing tert-butyl 4-aminomethylbenzoate E, compound F and a fifth solvent and react to obtain the fifth product system; filter the fifth product system, and dry the obtained precipitate to obtain compound A.

Preferably, the fifth solvent is one or more of ethanol, methanol, propanol and isopropanol; preferably, the mol ratio between tert-butyl 4-aminomethylbenzoate E and compound F is 1: 1.

An example is as follows: put 4-chloro-1,8-naphthalene dicarboxylic anhydride and tert-butyl 4-aminomethylbenzoate into ethanol to form a suspension. Stir at room temperature for 16 hours. The obtained precipitate was filtered and dried at 50° C. for 8 hours to obtain white powder tert-butyl-4-chloro-1,8-naphthalimidomethylbenzoate.

Preferably, both the first gelling solvent and the second gelling solvent are mixed solvents of water and ethanol. For example, ethanol/water mixed solvent with a volume ratio of 8-10.

In a word, the iron ion fluorescence sensor provided by the present invention has the following advantages:

(1) The Fe ³⁺ molecular fluorescent compound in the sensor has good photostability, the excitation (449nm) and emission light (521nm) are long-wavelength visible light, the Stokes shift is large (72nm), and the quantum yield is high. ;

(2) The sensor designed by the present invention can selectively detect the change of Fe ³⁺ , has strong anti-interference ability, and the synthesis method is simple, the detection cost is low, and can be reused;

(3) The shading layer of the sensor in the present invention can be used to better remove the interference of stray light in the environment or the color of the sample on the sample detection, and can also filter and isolate the macromolecular insolubles in the sample, so that only the sample The soluble substances in the test layer are in contact with the test layer to improve the detection accuracy;

(4) The first hydrogel and the second hydrogel in the present invention can allow Fe ³⁺ molecular fluorescent compounds and light-shielding fillers to be evenly dispersed on the surface of the base layer, further improving the uniformity and stability of the sensor. Moreover, the hydrogel can increase the adhesion, so that the test layer and the light-shielding layer can be easily fixed with the base layer, without UV curing, heat curing and other processes, which simplifies the fixing process;

(5) The excellent isolation between the hydrophilic macromolecular polymer group and the light-shielding layer also broadens its application range. For example, the sensor can be applied in the fields of bioelectrolyte fluorescence analysis, high-throughput drug screening and environmental monitoring, among which Uncured precursor substances (such as compound D) can also be used in the fields of fluorescent probes, cell staining, and fluorescent imaging.

(6) The iron ion fluorescence sensor of the present invention can detect the total concentration of ferrous ions and ferric ions in the liquid to be tested.

The preparation method of the above-mentioned iron ion molecular fluorescence sensor is relatively simple, and only needs to coat the test layer 20 and the light shielding layer 30 on the surface of the transparent resin base layer 10 once. for example:

The Fe ³⁺ molecular fluorescent compound was mixed with the D4 hydrogel solution (the D4 hydrogel was dissolved in ethanol and water), and stirred at room temperature for at least 18 h to make it uniformly dispersed in the hydrogel. Then the suspension is uniformly coated on the transparent resin base layer 10 with a doctor blade, and dried for at least 30 minutes. Then, the carbon black and the oxidant suspension mixed with the D6 hydrogel solution and stirred for at least 18 hours are continuously and uniformly coated on the Fe3 ⁺ fluorescent cellulose film with a scraper to obtain two layers of iron ion fluorescent sensors (upper layer) with uniform thickness. Add oxidant layer to carbon black, the lower layer is Fe ³⁺ fluorescent cellulose layer)

Further illustrate the beneficial effect of the present invention below by embodiment:

Example 1

Synthesis of compound 1

4-cyanobenzoic acid (80 g, 544 mmol) was dissolved in anhydrous _{CH2Cl2 (} 1000 mL). Add oxalyl chloride (104 mL, 816 mmol) and 10 mL of dimethylformamide (DMF). The resulting reaction mixture was stirred at room temperature for 1 hour until gas evolution ceased. Solvent was removed. The resulting residue was treated with 600 mL of a pyridine/tert-butanol mixture (1:1) and stirred at room temperature for 6 hours. The solvent was evaporated under reduced pressure, and the green residue was suspended in _H2O . The aqueous suspension was extracted with ethyl acetate (3 x 500 mL). The combined organic layers were washed with 10% KHSO ₄ (2×500 mL), H ₂ O (500 mL) NaHCO ₃ (500 mL), H ₂ O (500 mL) and brine (500 mL). The solvent was dried _{over Na2SO4} and evaporated. The crude product was purified by column chromatography using ethyl acetate/petroleum ether (1:4) to give white solid 58g (yield 52%).

Synthesis of Compound 2

tert-Butyl 4-cyanobenzoate (58 g, 37 mol) and nickel catalyst (5.8 g) were mixed in methanol (500 mL) and hydrogenated under a pressure of 10 kg for 16 hours. The catalyst was removed by filtration, and then the solvent was removed under reduced pressure to obtain 47 g of a white solid (yield 80%).

Synthesis of Compound 3

Put 46.4g (200mmol) of 4-chloro-1,8-naphthalic anhydride and 41.4g (200mmol) of tert-butyl 4-aminomethylbenzoate into 250mL EtOH to form a suspension. Stir at RT for 16 hours. The obtained precipitate was filtered and dried at 50° C. for 8 hours to obtain 48 g of white powder (yield 57%).

Synthesis of Compound 4

24.33g (225mmol) 2-aminopicoline and 31.3g (74.3mmol) tert-butyl-4-chloro-1,8-naphthalimide methylbenzoate and 13mL (74.6mmol) N,N-Diisopropylethylamine was suspended in 110 mL of N-methylpyrrolidone (NMP) and heated at 90°C for 18 hours. The mixture was cooled and poured into water (2L). The precipitate was filtered, then dissolved in _CHCl3 (800 mL) and washed with water (5 x 800 mL). The organic layer was dried _{over Na2SO4} , filtered and evaporated to give 63.55 g of crude product. The residue was triturated with hot methanol (600 mL), filtered and washed with cold methanol (600 mL). The resulting solid was recrystallized from hot CHCl ₃ to obtain 32.0 g (yield 87%) of yellow crystals, tert-butyl-4-aminomethylpyridinium-1,8-naphthalimidomethylbenzoate, Its H NMR spectrum is shown in Figure 2.

Synthesis of compound 5

Add 87.5 mL (1.14 mol) of trifluoroacetic acid (TFA) to 10.68 g (21.64 mmol) of tert-butyl-4-aminomethylpyridine-1,8-naphthalimidomethylbenzoate in CH ₂ Cl ₂ (160 mL). The resulting solution was stirred at room temperature for about 1 hour until thin layer chromatography (TLC) showed that most of tert-butyl-4-aminomethylpyridine-1,8-naphthalimidomethylbenzoate disappeared. The mixture was then diluted with 1:1 _CHCl3 :MeOH (1.2 L) and the solvent was evaporated. Repeat 6 times to remove TFA, and then put it on the pump for 30 minutes to dry it completely to obtain 9.35 g of yellow crystals (yield 99%), 4-aminomethylpyridine-1,8-naphthalimidomethyl Benzoic acid, its hydrogen nuclear magnetic resonance spectrogram is as shown in Figure 3.

Synthesis of compound 6

Aminoethylcellulose (5 g) was suspended in 50 mL of 2.5% aqueous sodium carbonate for 30 min, filtered, resuspended in 50 mL of DMF for 30 min, filtered, and washed twice with DMF to replace the entrapped water. The washed cellulose was then transferred to a solution containing 4-aminomethylpyridine-1,8-naphthalimidomethylbenzoic acid (0.13 g, 0.3 mmol), N,N-dicyclohexyl-1,3- Carbodiimide (DCC, 0.62g, 3mmol) and N-hydroxysuccinimide (NHS, 0.35g, 3mmol) were mixed in a solution of anhydrous DMF (20mL), and the mixed suspension was Stir for 20 hours. Then filter to obtain yellow cellulose fibers, wash with DMF (5×50mL), water (50mL), 0.2NHCl (2×50mL), water (50mL), 1.0NNaOH (2×50mL, 60°C, 30min), water (10 ×50mL), acetone (2×50mL), diethyl ether (2×50mL), and finally vacuum-dried for 16h to obtain 0.54g of yellow powder.

Fabrication of Iron Ion Fluorescence Sensor

Take 0.3 g of 4-aminomethylpyridine-1,8-naphthalimidomethylbenzamide cellulose passed through a 25 μm sieve, and dissolve it with 4.7 mL of D4 hydrogel solution (0.47 g of D4 hydrogel is dissolved in 3.807mL ethanol and 0.309mL water) were mixed, and stirred at room temperature for at least 18h, so that it was uniformly dispersed in the hydrogel. Then the suspension was uniformly coated on a 100 μm thick polyester (PET) film sheet (light transmittance greater than or equal to 88%) with a doctor blade, and dried for at least 30 minutes. A mixture of carbon black (0.15 g) and oxidant potassium permanganate (0.1 g) was then mixed with D6 hydrogel solution 4.85 mL (D6 hydrogel 0.475 g dissolved in 3.852 mL ethanol and 0.428 mL water) and stirred for at least 18 h. The suspension is evenly coated on the Fe ³⁺ fluorescent cellulose film with a scraper to obtain two layers of iron ion fluorescent sensors with uniform thickness (the upper layer is carbon black plus oxidant layer, the thickness is 150 μm, and the lower layer is Fe ³⁺ fluorescent cellulose layer, thickness 150 μm).

Fluorescence Performance Test of Iron Ion Fluorescence Sensor

(1) Spectral characteristics of iron ion fluorescent sensor for different concentrations of iron ions (Fe ³⁺ :Fe ²⁺ =1:1)

Dissolve 0.1622g of ferric chloride and 0.1268g of ferrous chloride in 0.05mol/L Tris-HCl buffer solution of pH 6.0, and use a 100mL volumetric flask to obtain 1.0×10 ^-2 mol/L of Fe ³⁺ standard solution and 1.0×10 ^-2 mol/L Fe ²⁺ standard solution. Continue to use this buffer solution to carry out multiple stepwise dilutions of the prepared Fe ³⁺ and Fe ²⁺ standard solutions in a ratio of 1:1, thereby obtaining the following series of standard solutions with different iron ion concentrations: 4 μmol/L, 8 μmol /L, 10μmol/L, 40μmol/L, 80μmol/L, 100μmol/L, 400μmol/L, 800μmol/L, 1000μmol/L and 10000μmol/L. The iron ion fluorescence sensor is fixed in the fluorescence cuvette along the diagonal position, and the voltage of the photomultiplier tube is 650V, and the excitation wavelength and emission wavelength are respectively 449nm and 521nm. Changes in fluorescence intensity of emitted light in a series of standard solutions with different iron ion concentrations. Fig. 4 is the change diagram of the fluorescent spectrum of the ferric ion fluorescent sensor made by the present invention along with the concentration of iron ion (Fe ³⁺ :Fe ²⁺ =1:1), it can be seen that the ferric ion fluorescent sensor is in the presence of Fe ³⁺ and Fe In the case of ²⁺ equal proportion coexistence, it shows strong fluorescence quenching. With the increase of iron ion concentration, the fluorescence intensity of the sensor at 521nm decreased gradually. Fig. 5 is the changing diagram of the fluorescent intensity of the ferric ion fluorescent sensor prepared by the present invention as the concentration of ferric ions (Fe ³⁺ :Fe ²⁺ =1:1) increases, from this figure it can be seen that when the ferric ions (Fe ³⁺ :Fe ²⁺ ＝1:1) concentration in the range of 4μmol/L-1000μmol/L, the fluorescence intensity has a good linear relationship with the iron ion (Fe ³⁺ :Fe ²⁺ ＝1:1) concentration, its The fitted linear equation can quantitatively detect iron ions (Fe ³⁺ :Fe ²⁺ =1:1). The detection limit of iron ion (Fe ³⁺ :Fe ²⁺ =1:1) concentration was calculated as 1.36μmol/L according to the ratio of the standard deviation of 3 times 10 blank solutions and the slope of the fitting equation.

(2) Spectral characteristics of 16 other heavy metal ions by the iron ion fluorescent sensor

16 metal ion salts [NaCl, KCl, CH ₃ COOLi·2H ₂ O, Al(NO ₃ ) ₃ , CaCl ₂ , MgCl ₂ ·6H ₂ O, ZnCl ₂ , CoCl ₂ ·6H ₂ O, MnCl ₂ ·4H ₂ O, CrCl ₃ 6H ₂ O, BaCl ₂ 2H ₂ O, NiCl ₂ 6H ₂ O, CuCl ₂ 2H ₂ O, CdCl ₂ 2.5H ₂ O, Pb(NO ₃ ) ₂ , HgCl ₂ ] The 0.05mol/L Tris-HCl buffer solution with pH6.0 is accurately configured into a stock solution with a concentration of 10mmol/L, and then diluted into 16 kinds of ion standard solutions with a concentration of 1000μmol/L for use. At the same time, a standard solution in which each metal ion coexists with iron ions (Fe ³⁺ :Fe ²⁺ =1:1) is also configured, so that a single metal ion in each standard solution and iron ion (Fe ³⁺ :Fe ²⁺ =1 : 1) the concentration is 1000 μmol/L. The fluorescence selectivity experiment is shown in Figure 6. Na ⁺ , K ⁺ , Li ⁺ , Al ³⁺ , Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , Fe ²⁺ , Co ²⁺ , Mn ²⁺ , Cr ³⁺ , Ba ²⁺ , Ni ²⁺ , Cu ²⁺ , Cd ²⁺ , Pb ²⁺ , Hg ²⁺ , Fe ³⁺ , Fe ²⁺ and iron ion (Fe ³⁺ :Fe ²⁺ = ¹ :1) standard Take 2ml of the solution and add them to the cuvettes with the iron ion fluorescence sensor obliquely inserted. After the fluorescence is stable, use the excitation light with a wavelength of 449nm under the voltage of 650V to detect the change of the fluorescence intensity at 521nm. Observing Figure 6, it can be seen that the iron ion fluorescent sensor has an obvious response effect to Fe ³⁺ , Fe ²⁺ and iron ions (Fe ³⁺ :Fe ²⁺ =1:1), and the fluorescence intensity at 521nm is reduced to the lowest value, And the fluorescence intensities of the three are similar, which shows that the sensor has good selectivity to Fe ³⁺ , Fe ²⁺ and iron ions (Fe ³⁺ :Fe ²⁺ =1:1). After adding Cu ²⁺ , the fluorescence intensity of the sensor is also slightly reduced, but other equivalent metal ions have basically no effect on the fluorescence emission intensity of the optode film. In order to further study the interference effect of other common metal cations on the determination of iron ions (Fe ³⁺ :Fe ²⁺ = 1:1), we conducted a competition experiment, that is, 1000 μmol/L containing other ions (both concentrations were 1000 μmol/L) The solution of L iron ions (Fe ^{3 +} :Fe ²⁺ =1:1) was added to the cuvette containing the iron ion fluorescence sensor for measurement (the results are shown in the white bar graph in FIG. 7 ). According to the competition experiment, except for Cu ²⁺ , Fe ³⁺ and Fe ²⁺ , the fluorescence emission intensity at 521nm did not change significantly when other ions coexisted with Fe ³⁺ . From the data of Fe ³⁺ and Fe ²⁺ , it can be seen that the sensor has good recognition for both Fe ³⁺ and Fe ²⁺ , and there is no difference in the recognition ability of the two. Therefore, in addition to Cu ²⁺ , other common metal cations and anions (different metal cations are added in the form of chloride, nitrate or acetate) will not interfere with the iron ion (Fe ³⁺ :Fe ²⁺ =1:1 ) determination. When the concentration of Cu ²⁺ is reduced to 100 μmol/L, the detection of 1000 μmol/L iron ion (Fe ³⁺ :Fe ²⁺ =1:1) no longer interferes. Therefore, it is feasible to use this sensor for iron ion detection.

(3) The ability of the iron ion fluorescence sensor to identify the iron ion mixture containing different proportions of Fe ³⁺ and Fe ²⁺

In order to further understand whether there is a difference in the recognition ability of the iron ion fluorescent sensor for Fe ³⁺ and Fe ²⁺ , a series of iron ion mixtures containing different proportions of Fe ³⁺ and Fe ²⁺ were configured so that the final total iron ion The concentrations were all 1000 μM. These treatments include all Fe ³⁺ , the concentration ratio of Fe ³⁺ and Fe ²⁺ is 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:1 4, 1:5, and all Fe ²⁺ . Take 2ml of iron ion solutions of various treatments and add them into cuvettes obliquely inserted with iron ion fluorescence sensors. After the fluorescence is stable, use excitation light with a wavelength of 449nm to detect the change of fluorescence intensity at 521nm at a voltage of 650V. The result is shown in Figure 8. According to Figure 8, when the total concentration of iron ions is the same, the relative deviations of the emitted light fluorescence values of each treatment are all below 4%, and the one-way analysis of variance shows that in the case of P<0.05, the differences in the emitted light fluorescence intensity of each treatment are not significant. Significantly, this shows that the iron ion sensor has the same recognition ability for Fe ³⁺ and Fe ²⁺ , and can be used to accurately detect the concentration of total iron ions with different concentration ratios of Fe ³⁺ and Fe ²⁺ .

Example 2

The technique of each step in this embodiment is the same as Example 1, and the only difference is: in the synthetic process of compound 1, adjust the consumption of oxalyl chloride, make the mol ratio of 4-cyanobenzoic acid and oxalyl chloride be 2:3, The volume ratio between pyridine and tert-butanol is 1.1:1. The yield of the final compound 1 was 49%.

Example 3

The process of each step in this example is the same as that of Example 1, the only difference being that during the synthesis of compound 1, the amount of oxalyl chloride was adjusted so that the molar ratio of 4-cyanobenzoic acid and oxalyl chloride was 3:5. The yield of the final compound 1 was 53%.

Example 4

The process of each step in this embodiment is the same as that of Example 1, the only difference being that in the synthesis process of compound 1, oxalyl chloride is replaced by thionyl chloride, and its amount is adjusted to make 4-cyanobenzoic acid and chlorinated The molar ratio of sulfoxide is 3:2. Pyridine was replaced by 4-dimethylaminopyridine, and the amount was adjusted so that the volume ratio between 4-dimethylaminopyridine and tert-butanol was 1.2:1, and the final yield of compound 1 was 45%.

Example 5

The technique of each step in this embodiment is with embodiment 1, and difference is only: in the synthetic process of compound 2, adjust the consumption of catalyst, make the weight ratio between 4-cyanobenzoic acid tert-butyl ester and nickel catalyst be 20:3, adjust the amount of methanol, so that the weight ratio between tert-butyl 4-cyanobenzoate and methanol is 1:8. The yield of compound 2 was 82%.

Example 6

The technique of each step in this embodiment is with embodiment 1, and difference is only: in the synthetic process of compound 2, adjust the consumption of catalyst, make the weight ratio between 4-cyanobenzoic acid tert-butyl ester and nickel catalyst be 20:3, adjust the amount of methanol so that the weight ratio between tert-butyl 4-cyanobenzoate and methanol is 3:20. The yield of compound 2 was 84%.

Example 7

The technique of each step in this embodiment is the same as that of Example 1, and the only difference is that in the synthesis process of compound 2, the nickel catalyst is replaced by a palladium carbon catalyst, and the consumption of the catalyst is adjusted to make 4-cyanobenzoic acid tert-butyl The weight ratio between the ester and the palladium carbon catalyst is 15:1, and the consumption of methyl alcohol is adjusted so that the weight ratio between tert-butyl 4-cyanobenzoate and methyl alcohol is 1:6. The yield of compound 2 was 74%.

Example 8

The process of each step in this embodiment is the same as that of Example 1, the only difference is that during the synthesis of compound 4, the amount of 2-aminopicoline and N,N-diisopropylethylamine is adjusted to make tert-butyl The molar ratio between methyl-4-chloro-1,8-naphthalimidomethylbenzoate, 2-aminopicoline and N,N-diisopropylethylamine is 1:1 :1. The yield of compound 4 was 85%.

Example 9

The process of each step in this embodiment is the same as that of Example 1, the only difference is that during the synthesis of compound 4, the amount of 2-aminopicoline and N,N-diisopropylethylamine is adjusted to make tert-butyl The molar ratio between 4-chloro-1,8-naphthalimidomethylbenzoate, 2-aminopicoline and N,N-diisopropylethylamine is 6:5 :15. The yield of compound 4 was 82%.

Example 10

The process of each step in this example is the same as that of Example 1, the only difference is that during the synthesis of compound 4, N,N-diisopropylethylamine is replaced by triethylamine, and the 2-aminomethyl The amount of pyridine and triethylamine such that the molar ratio between tert-butyl-4-chloro-1,8-naphthalimidomethylbenzoate, 2-aminopicoline and triethylamine It is 8:5:5. The yield of compound 4 was 73%.

Example 11

The process of each step in this example is the same as in Example 1, the only difference is that in the synthesis process of compound 5, the amount of trifluoroacetic acid was adjusted to make tert-butyl-4-aminomethylpyridine-1,8-naphthalene The mole amount of dicarboximidomethylbenzoate is 1.8% of the mole amount of trifluoroacetic acid. The yield of compound 5 was 97%.

Example 12

The process of each step in this example is the same as that of Example 1, the only difference is that in the synthesis process of compound 5, the amount of trifluoroacetic acid was adjusted to make tert-butyl-4-aminomethylpyridine-1,8-naphthalene The molar amount of dicarboximidomethylbenzoate is 2.0% of the molar amount of trifluoroacetic acid. The yield of compound 5 was 98%.

Example 13

The process of each step in this embodiment is the same as in Example 1, the only difference being that in the synthesis process of compound 5, trifluoroacetic acid is replaced by a mixed reagent of hydrochloric acid and ethyl acetate with a volume ratio of 1:2, and its The dosage, the mole number of tert-butyl-4-aminomethylpyridine-1,8-naphthalimide methylbenzoate is 3.0% of the mole number of the mixed reagent. The yield of compound 5 was 75%.

It can be seen from the above examples that the iron ion molecular fluorescence sensor provided by the present invention has the advantages of high measurement efficiency, high sensitivity, and high accuracy when measuring the concentration of iron ions in a sample, and can detect any proportion of ferrous ions and The total concentration of ferric ions.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (27)

1. An iron ion molecular fluorescence sensor, is characterized in that, comprises: transparent resin base layer (10); a test layer (20), disposed on one side surface of the transparent resin base layer (10), the test layer (20) comprising a first gel base material and dispersed in the first gel base material Fe ³⁺ molecular fluorescent compounds; A light-shielding layer (30), arranged on the surface of the test layer (20) away from the transparent resin base layer (10), the light-shielding layer (30) comprising a second gel base material dispersed in the The opacifying filler and the oxidizing agent in the second gel matrix; Wherein, the Fe3 ⁺ molecular fluorescent compound has a structure shown in formula I: Formula I In the formula I, Polym is an aminated hydrophilic macromolecular polymer group. 2. The iron ion molecular fluorescence sensor according to claim 1, wherein said Polym is a residue formed by dehydrogenation of aminocellulose, a residue formed by dehydrogenation of aminomaltodextrin or dehydrogenation of aminovinylpyrrolidone formed residues. 3. iron ion molecular fluorescence sensor according to claim 2, is characterized in that, described amino cellulose is amino ethyl cellulose, amino hydroxyethyl cellulose, amino hydroxypropyl cellulose and amino carboxymethyl cellulose one or more of the elements. 4. The iron ion molecular fluorescence sensor according to claim 1, wherein the oxidant is one or more of potassium permanganate, ceric sulfate and sodium bismuthate. 5. The iron ion molecular fluorescence sensor according to any one of claims 1 to 4, characterized in that, the light-shielding filler is carbon black. 6. The iron ion molecular fluorescence sensor according to claim 5, wherein the first gel substrate and the second gel substrate are respectively selected from D4 hydrogel, D6 hydrogel, propylene One or more of amide-acrylonitrile copolymer and polyvinyl alcohol. 7. The iron ion molecular fluorescence sensor according to any one of claims 1 to 4, characterized in that, the material of the transparent resin base layer (10) is PET, PMMA, PC, PVC, PS, PP and ABS one or more of. 8. a preparation method of the ferric ion molecular fluorescence sensor described in any one of claims 1 to 7, is characterized in that, described preparation method comprises the following steps: Step L1, providing a transparent resin base layer; Step L2, mixing the Fe3 ⁺ molecular fluorescent compound, the gel material of the first gel base material and the first gel solvent, coating the obtained mixture on one side surface of the transparent resin base layer, and drying Form a test layer; Step L3, mixing the light-shielding filler, the oxidant, the gel material of the second gel base material and the second gel solvent, and coating the obtained mixture on the surface of the test layer on the side away from the transparent resin base layer , forming a light-shielding layer after drying, and then obtaining the iron ion molecular fluorescence sensor; Wherein, the Fe3 ⁺ molecular fluorescent compound has a structure shown in formula I: Formula I In the formula I, Polym is an aminated hydrophilic macromolecular polymer group. 9. preparation method according to claim 8, is characterized in that, described ^Fe Molecular fluorescent compound is prepared by the following method: In step S1, compound A and compound B are condensed to form compound C; the structures of compound A, compound B and compound C are as follows, wherein X in compound A is a halogen: A B C Step S2, hydrolyzing the compound C to obtain the compound D; the structure of the compound D is as follows: C D Step S3, performing condensation amidation reaction between the compound D and the aminated hydrophilic macromolecular polymer to obtain Fe ^{3 +} molecular fluorescent compound. 10. The preparation method according to claim 9, characterized in that the aminated hydrophilic macromolecular polymer is aminocellulose, aminomaltodextrin or aminopolyvinylpyrrolidone. 11. The preparation method according to claim 10, characterized in that, before the step S1, the preparation method further comprises the step of preparing the compound A, which comprises: Carry out esterification reaction with 4-cyanobenzoic acid and tert-butanol to obtain tert-butyl 4-cyanobenzoate; The tert-butyl 4-cyanobenzoate, catalyst and methanol are mixed to form a mixed system, and hydrogen gas is introduced into the mixed system to carry out a hydrogenation reaction to obtain tert-butyl 4-aminomethylbenzoate E; wherein the Catalyst is one or more in nickel catalyst, palladium carbon catalyst and cobalt catalyst; The tert-butyl 4-aminomethylbenzoate E is reacted with the compound F to obtain the compound A; wherein the tert-butyl 4-aminomethylbenzoate E and the compound F have the following structure: E F A Wherein X in the compound F is a halogen. 12. The preparation method according to any one of claims 9 to 11, wherein the step S1 comprises: mixing the compound A, the compound B and the acid-binding agent with a first solvent to obtain a first mixture; performing the condensation reaction on the first mixture at a temperature of 80-100° C. to obtain a first product system; The first product system was cooled and poured into water, and filtered to obtain a precipitate, which was the compound C. 13. The preparation method according to claim 12, characterized in that, The first solvent is one or more of N-methylpyrrolidone, N,N-dimethylacetamide, dimethylsulfoxide and tetrahydrofuran; The acid-binding agent is one or more of N,N-diisopropylethylamine, N,N-dimethylformamide, 4-dimethylaminopyridine and triethylamine; The molar ratio among the compound A, the compound B and the acid-binding agent is 1-6:1-5:1-15. 14. The preparation method according to claim 12, characterized in that, after the filtering step, said step S1 also includes the step of washing said precipitate, said washing step comprising: Dissolving the precipitate in chloroform, adding water to it for washing, and separating the layers to obtain an organic phase and an aqueous phase; The organic phase was dried over anhydrous sodium sulfate, filtered and evaporated to give the compound C. 15. according to the preparation method described in any one in claim 9 to 11, it is characterized in that, described step S2 comprises: mixing and reacting the compound C, the carbonyl removing reagent and the second solvent to obtain the second product system; The second product system was diluted with a chloroform/methanol mixed solution with a volume ratio of 1:1, and then the solvent was evaporated to obtain the compound D. 16. The preparation method according to claim 15, characterized in that, The carbonyl removal reagent is trifluoroacetic acid, a mixed reagent of hydrochloric acid and ethyl acetate with a volume ratio of 1:2, or silica gel; The second solvent is dichloromethane and/or chloroform; The number of moles of the compound C is 1.8-2.0% of the number of moles of the carbonyl removal reagent. 17. The preparation method according to claim 16, characterized in that, the moles of the compound C are 1.9% of the moles of the carbonyl removal reagent. 18. The preparation method according to any one of claims 9 to 11, wherein the step S3 comprises: mixing and reacting the compound D, the aminated hydrophilic macromolecular polymer, a dehydrating agent, a carbonyl activator and a third solvent to obtain a third product system; The third product system is filtered, and the filtered precipitate is washed and dried to obtain the Fe ³⁺ molecular fluorescent compound. 19. The preparation method according to claim 18, characterized in that, The dehydrating agent is N,N-dicyclohexyl-1,3-carbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and diisopropyl One or more of carbodiimides; The carbonyl activator is N-hydroxyl succinimide and/or N-hydroxyl sulfosuccinimide; The third solvent is one or more of N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide and hexamethylphosphoric triamide ; The dosage of the compound D is 2-3% of the weight of the aminated hydrophilic macromolecular polymer. 20. The preparation method according to claim 18, characterized in that, before mixing the aminated hydrophilic macromolecular polymer, the step S3 further comprises: mixing the aminated hydrophilic macromolecular polymer The molecular polymer is suspended in sodium carbonate aqueous solution, filtered, resuspended in DMF, filtered, and washed with DMF to obtain the pretreated aminated hydrophilic macromolecular polymer. 21. preparation method according to claim 11, is characterized in that, the step of carrying out esterification reaction with described 4-cyanobenzoic acid and described tert-butyl alcohol comprises: Mixing and reacting the 4-cyanobenzoic acid and the fourth solvent of the acylating reagent to obtain an intermediate; After removing the solvent in the intermediate, it is mixed and reacted with an esterification catalyst and tert-butanol to obtain a fourth product system; The fourth product system is purified to obtain the tert-butyl 4-cyanobenzoate. 22. The preparation method according to claim 21, characterized in that, The acylating reagent is one or more of oxalyl chloride, thionyl chloride, phosphorus trichloride and phosphorus pentachloride; The esterification catalyst is one or more of pyridine, N,N-dimethylformamide, 4-dimethylaminopyridine and triethylamine; The molar ratio between described 4-cyanobenzoic acid and described acylating reagent is 2～3:3～5; The volume ratio between described esterification catalyst and described tert-butanol is 1～1.1:1 . 23. The preparation method according to claim 11 or 21, characterized in that, in the step of preparing the tert-butyl 4-aminomethylbenzoate E, the tert-butyl 4-cyanobenzoate and the The weight ratio between the catalysts is 10~20:1~3; the weight ratio between the tert-butyl 4-cyanobenzoate and the methanol is 1~3:8~20. 24. The preparation method according to claim 23, characterized in that, after the hydrogen gas is introduced, the pressure of the reaction system is 0.8-1.2 MPa. 25. according to the described preparation method of claim 11 or 21, it is characterized in that, the step that described tert-butyl 4-aminomethylbenzoate E is reacted with described compound F comprises: Mixing and reacting the tert-butyl 4-aminomethylbenzoate E, the compound F and the fifth solvent to obtain the fifth product system; The fifth product system is filtered, and the obtained precipitate is dried to obtain the compound A. 26. The preparation method according to claim 25, characterized in that, The fifth solvent is one or more of ethanol, methanol, propanol and isopropanol; The molar ratio between the tert-butyl 4-aminomethylbenzoate E and the compound F is 1:1. 27. The preparation method according to claim 8, characterized in that, both the first gelling solvent and the second gelling solvent are mixed solvents of water and ethanol.