CN115651641A - Water vapor fluorescence sensor and preparation method thereof - Google Patents

Abstract

The invention relates to a water vapor fluorescence sensor and a preparation method thereof, wherein the water vapor fluorescence sensor is obtained by compounding a compound M1 and a base material M2, and the water vapor sensor designed by the invention has good water vapor sensing performance. The ether oxygen atom in the M1 molecule and the hydroxyl in the matrix material form a hydrogen bond, so that the ether oxygen atom is dispersed on the surface of the matrix, and monodisperse green fluorescence is emitted; as water molecules are easier to form hydrogen bonds with hydroxyl groups on the matrix, when the water vapor concentration is increased, M1 molecules are dissociated from the matrix material, so that orange associated complex fluorescence is formed. The method has the advantages of simple operation, high sensitivity, convenient preparation, field detection and the like, and provides another choice for the water sensing technology.

Description

A kind of water vapor fluorescent sensor and preparation method thereof

technical field

The invention relates to the field of fluorescent chemical sensors, in particular to a water vapor fluorescent sensor and a preparation method thereof.

Background technique

Water is the most common impurity in many organic solvents, and its diagnosis is of great significance in many fields such as laboratory chemistry, fine chemical industry, biomedical analysis and food processing. Karl Fischer titration is a commonly used method for the determination of water content in organic solvents. It was originally developed in the 1930s in which water reacts with a reagent and converts it into a non-conductive substance. Although this technique has the advantages of absolute measurement, high sensitivity, applicable to both liquid and solid samples, low cost, and wide application range, there are also some disadvantages that cannot be ignored, including the need for specialized equipment and skilled operators, which limits its application. application. Electrochemical and electrophysical sensors are other sensing mechanisms for quantifying water content. Their high stability and ease of calibration and use make them suitable for industrial applications. However, the reported limitations of these methods are lack of sufficient precision and portability for real-time analysis, and susceptibility to electromagnetic radiation due to electronic properties. Compared with the above technologies, the optical water sensing technology based on fluorophore or chromophore materials has many advantages such as simple operation, high sensitivity, convenient preparation, and convenient on-site detection, which provides another choice for water sensing technology.

Contents of the invention

Based on this, the present invention develops a new type of water vapor fluorescence sensor by introducing hydrophilic ether chains on phenylene vinylene derivatives to endow them with amphiphilic properties. The hydrogen bond between the hydroxyl group in the silica gel, the ether oxygen atom, and the water molecule is used to induce the association-disassociation phenomenon of the sensor molecule, thereby exhibiting significantly different fluorescent properties and achieving the purpose of water vapor sensing.

To achieve the above object, the technical solution provided by the invention is:

A kind of water vapor fluorescent sensor, this water vapor fluorescent sensor is obtained by compounding compound M1 and matrix material M2, and the structural formula of compound M1 is as follows:

Wherein the range of m is 1-3.

The matrix material M2 is one of chitosan, nanocellulose and silicon dioxide.

The matrix material M2 has a porous structure.

The preparation method of water vapor fluorescent sensor comprises the following steps:

a) Put 2,5-dihydroxyterephthalaldehyde, bromobutane, anhydrous potassium carbonate and solvent N,N-dimethylformamide into a round-bottomed flask at one time, and react at a constant temperature of 80°C for 48 hours; After completion, the insoluble inorganic salts were removed by vacuum filtration, and the filtrate was concentrated by a rotary evaporator, and recrystallized with methanol to obtain the first reactant 1;

b) Put the first reactant 1, the second reactant 2, the organic base and the mixed solvent of tert-butanol/tetrahydrofuran into the round bottom flask at one time; stir and react at a constant temperature of 70°C for 20 minutes; after the reaction is completed, cool to room temperature, The reactant was poured into water, extracted with dichloromethane, the organic phase was dried over anhydrous Na ₂ SO ₄ , concentrated with a rotary evaporator, and the target molecule M1 was obtained by column chromatography;

c) dissolving the molecule M1 obtained in step b in a tetrahydrofuran solvent, using this as an impregnating solution to impregnate the substrate M2, and obtaining the final water vapor fluorescence sensor after the solvent is dried.

The organic base in step b) is one or more of potassium tert-butoxide, sodium tert-butoxide, tetrabutylammonium hydroxide, tetramethylguanidine, 1,8-diazabicycloundec-7-ene kind.

The concentration range of M1 in the immersion liquid in step c) is 0.001-0.005 mol/liter, and the immersion time of the base material M2 is more than 20 minutes.

The present invention also protects the application of the water vapor fluorescent sensor in water vapor sensing materials.

Compared with prior art, the beneficial effect of the present invention is:

The present invention develops a new type of water vapor fluorescence sensor by introducing hydrophilic ether chains on phenylene vinylene derivatives to endow them with amphiphilic properties. The hydrogen bond between the hydroxyl group in the silica gel, the ether oxygen atom and the water molecule is used to induce the association-disassociation phenomenon of the sensor molecule, thereby exhibiting significantly different fluorescent properties and achieving the purpose of water vapor sensing. The research results show that when the water vapor sensor molecules are dispersed on the silica gel-based material, the ether oxygen atoms in the sensor molecules form hydrogen bonds with the silica gel, causing them to disperse on the surface of the substrate, thereby emitting monodisperse green fluorescence; It is easier to form hydrogen bonds with silicon hydroxyl groups. When the water vapor concentration increases, the sensor molecules will dissociate from the matrix material, thereby forming an orange associate fluorescence, thus showing good water vapor sensing performance.

The water vapor sensor designed in the present invention exhibits good water vapor sensing performance. The ether oxygen atoms in the M1 molecule form hydrogen bonds with the hydroxyl groups in the matrix material, causing them to disperse on the surface of the matrix, thus emitting monodisperse green fluorescence; since water molecules are more likely to form hydrogen bonds with the hydroxyl groups on the matrix, when the water vapor concentration increases When , M1 molecules dissociate from the matrix material, thus forming orange-colored association fluorescence. This method has many advantages such as simple operation, high sensitivity, convenient preparation, and on-site detection, which provides another choice for water sensing technology.

Description of drawings

Figure 1 is the fluorescence photo of VS-1 under different humidity.

Figure 2 is the fluorescence spectrum of RS-4 before and after standing for 2 hours.

Fig. 3 is the fluorescence and visible light photos of VS-1, VS-2, VS-3 and VS-4.

Figure 4 is the fluorescence photo of RS-4 under different humidity.

Fig. 5 is the fluorescent photos of RS-1, RS-2 and RS-3 under different humidity.

Detailed ways

The above-mentioned content of the present invention will be described in further detail below by the form of the embodiment, but this should not be interpreted as the scope of the above-mentioned theme of the present invention being limited to the following embodiments, all technologies realized based on the above-mentioned content of the present invention belong to scope of the invention.

The water vapor fluorescence sensor prepared by the present invention is tested according to the following method:

H NMR spectrum and C NMR spectrum were determined by Bruker AVANCE II NMR instrument, tetramethyl silicon was used as internal standard, and solvent was deuterated chloroform or deuterated dimethyl sulfoxide. Fluorescence spectra were measured with a Shimadzu RF-5301PC fluorescence spectrophotometer.

Example 1: Preparation of Water Vapor Fluorescence Sensor VS-1

The preparation route is as follows:

a) Mix 2,5-dihydroxyterephthalaldehyde (2g, 121mmol), bromobutane (2.41mL, 228mmol), anhydrous potassium carbonate (3.3g, 239mol) and 30ml of N,N-dimethylformaldehyde The amide was put into a round bottom flask at one time, and the oil bath was heated to 80°C, stirred and refluxed at a constant temperature for 48 hours, and the reaction was stopped when the raw materials disappeared by thin-layer chromatography. After the reaction was completed, the insoluble inorganic salt was removed by vacuum filtration, and the filter cake was washed three times with N,N-dimethylformamide. After the filtrate was concentrated by a rotary evaporator, it was recrystallized with methanol as a solvent to obtain the first reactant 1 .

b) The first reactant 1 (100mg, 0.299mmol), the second reactant 2 (190mg, 0.719mmol), an organic base, 8mL tert-butanol, and 8mL tetrahydrofuran are thrown into a round-bottomed flask at one time, and the oil bath is heated to 70°C. Then, potassium tert-butoxide (36mg, 0.321mmol) and tetrabutylammonium hydroxide (1.8mL, 2.53mmol) were added into the round-bottomed flask, stirred at constant temperature for 20 minutes, and the reaction was stopped until the raw materials disappeared by thin-layer chromatography. After the reaction was completed, it was cooled to room temperature, the reactant was poured into water, extracted with dichloromethane, the organic phase was dried over anhydrous Na ₂ SO ₄ , concentrated with a rotary evaporator, and the target molecule M1 was obtained by column chromatography.

c) Dissolving the M1 molecule obtained in step b in a tetrahydrofuran solvent, using this as an impregnating solution to impregnate the substrate M2, and standing and drying at room temperature for 5 hours to obtain the final water vapor fluorescence sensor.

Wherein the value of m in the target molecule M1 is 2, the concentration of the M1 impregnation solution in step c is 0.003 mol/L, and the matrix M2 is silicon dioxide.

Example 2: Preparation of Water Vapor Fluorescence Sensor VS-2

The specific preparation steps are as follows: the same part as in Example 1 will not be repeated, and the difference with Example 1 is that the concentration of the M1 soaking solution in step c is 0.001 mol/liter.

Example 3: Preparation of Water Vapor Fluorescence Sensor VS-3

The specific preparation steps are as follows: the same part as in Example 1 will not be repeated, and the difference with Example 1 is that the concentration of the M1 soaking solution in step c is 0.002 mol/liter.

Example 4: Preparation of Water Vapor Fluorescence Sensor VS-4

The specific preparation steps are as follows: the same part as in Example 1 will not be repeated, and the difference with Example 1 is that the concentration of the M1 soaking solution in step c is 0.004 mol/liter.

Comparative Example 1: Preparation of RS-1

Concrete preparation steps are as follows: its identical part with embodiment 1 repeats no more, and the difference with embodiment 1 is, used matrix material M2 in the step c is polyester non-woven fabric.

Comparative Example 2: Preparation of RS-2

Concrete preparation steps are as follows: its identical part with embodiment 1 repeats no more, and the difference with embodiment 1 is, used matrix material M2 in the step c is polypropylene non-woven fabric.

Comparative Example 3: Preparation of RS-3

The specific preparation steps are as follows: the same part as in Example 1 will not be repeated, and the difference with Example 1 is that the matrix material M2 used in step c is filter paper.

Comparative Example 4: Preparation of RS-4

The specific preparation steps are as follows: the same part as in Example 1 will not be repeated, and the difference with Example 1 is that the concentration of the M1 soaking solution in step c is 0.0001 mol/liter.

Hereinafter, the water vapor fluorescence sensor and its preparation method of the present invention will be further described in conjunction with some embodiments.

It can be seen from the fluorescence photos of the sensor VS-1 under different water vapors (Fig. 1), as the water vapor gradually increases from 1g/m ³ to 25g/m ³ , the fluorescence color of the system gradually changes from green to orange yellow, showing a very Obvious ratiometric fluorescent sensing characteristics. This process can be observed directly with the naked eye. Water molecules can form stronger hydrogen bonds with the hydroxyl groups on the surface of the silica gel, which will destroy the hydrogen bonds formed between the ether oxygen atoms in the M1 molecule and the silicon hydroxyl groups. Therefore, we preliminarily speculate that the fluorescence color change under the action of water vapor is due to the re-aggregation of M1 molecules induced by it.

When the concentration of M1 was low, there was no significant shift in the fluorescence spectrum before and after standing, and RS-4 showed bright green fluorescence (Fig. 2). The main reason for this phenomenon is that when the concentration of M1 is low, the molecules are already in a dispersed state, and there is no aggregation-hydrogen bond-induced dispersion process. When the M1 loading concentration reaches 0.004M/L, because the concentration is too high, the hydrogen bonds on the surface of the silica gel are not enough to induce all the M1 molecules to disperse on the surface, so the VS-4 system still shows a relatively obvious aggregated orange after standing. Yellow fluorescence, the degree of blue shift of the fluorescence spectrum is also weakened (Figure 3). The control example RS-4 does not exhibit obvious water vapor fluorescence sensing characteristics. It can be seen from Figure 4 that when the concentration of the M1 solution is as low as 0.0001M/L, the fluorescence color of the system does not change significantly as the water vapor increases from 1g/m ³ to 25g/m ³ . This phenomenon further confirmed our speculated water vapor sensing mechanism.

The composites prepared with polyester (PET) and polypropylene (PP) non-woven fabrics as impregnated substrates did not show obvious water vapor sensing properties (Fig. 5). Under the water content of 1g/m ³ , 10g/m ³ , and 25g/m ³ respectively, the fluorescence colors of RS-1, RS-2 and RS-3 systems did not change significantly, showing orange-yellow fluorescence. The main reason for this phenomenon is that the content of groups on the surface of the substrate is different. Both PET and PP surfaces do not contain hydroxyl groups, so they cannot induce M1 molecules to disperse on the substrate surface through hydrogen bonding. Although filter paper is made of cellulose, due to the strong crystallinity of cellulose, the hydroxyl content on the surface of the fiber is not as good as that of porous silica gel, so it does not have obvious water vapor sensing characteristics.

It can be seen that the water vapor fluorescence sensor provided by the present invention can respond in a wide range of humidity. This technical route has many advantages such as simple operation, high sensitivity, convenient preparation, and on-site detection, which provides another choice for water sensing technology.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Any skilled person who is familiar with the profession, without departing from the scope of the technical solutions of the present invention, according to the technical essence of the present invention, Any simple modifications, equivalent replacements and improvements made in the above embodiments still fall within the protection scope of the technical solution of the present invention.

Claims (7)

1. The water vapor fluorescence sensor is characterized by being obtained by compounding a compound M1 and a base material M2, wherein the compound M1 has the following structural formula:

wherein m ranges from 1 to 3.

2. The aqueous vapor fluorescence sensor according to claim 1, wherein the matrix material M2 is one of chitosan, nanocellulose and silica.

3. The aqueous vapor fluorescence sensor according to claim 2, wherein the matrix material M2 is a porous structure.

4. The method for preparing the water vapor fluorescence sensor according to any one of claims 1 to 3, which is characterized by comprising the following steps:

a) Putting 2, 5-dihydroxy terephthalaldehyde, bromobutane, anhydrous potassium carbonate and solvent N, N-dimethylformamide into a round-bottom flask at one time, and reacting at the constant temperature of 80 ℃ for 48 hours; after the reaction is finished, carrying out vacuum filtration to remove insoluble inorganic salt, concentrating the filtrate by using a rotary evaporator, and recrystallizing by using methanol to obtain a first reactant 1;

b) Putting a first reactant 1, a second reactant 2, an organic base and a tert-butyl alcohol/tetrahydrofuran mixed solvent into a round-bottom flask at one time; stirring and reacting for 20 minutes at a constant temperature of 70 ℃; after completion of the reaction, it was cooled to room temperature, the reaction was poured into water, extracted with dichloromethane and the organic phase was passed over anhydrous Na ₂ SO ₄ Drying, concentrating with rotary evaporator, and performing column chromatography to obtain target molecule M1;

c) And c, dissolving the M1 molecules obtained in the step b in a tetrahydrofuran solvent, taking the solution as an impregnation solution to impregnate the matrix M2, and drying the solvent to obtain the final water vapor fluorescence sensor.

5. The method for preparing the water vapor fluorescence sensor according to claim 4, wherein the organic base in the step b) is one or more of potassium tert-butoxide, sodium tert-butoxide, tetrabutylammonium hydroxide, tetramethylguanidine and 1, 8-diazabicycloundecen-7-ene.

6. The method for preparing the water vapor fluorescence sensor according to claim 4, wherein the concentration of M1 in the dipping solution in the step c) is in the range of 0.001-0.005 mol/L, and the dipping time of the matrix material M2 is more than 20 minutes.

7. Use of the moisture fluorescent sensor according to any one of claims 1 to 3 in a moisture sensing material.

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