Preparation method and application of phenanthrolinyl Schiff base derivative

Abstract

The invention relates to a preparation method and application of a phenanthroline-based Schiff base derivative, a Schiff base substance is synthesized by amine-aldehyde condensation reaction between 1, 10-phenanthroline-2, 9-dicarboxaldehyde (PDL) and thionine (Thi), the PDL has an excellent carbon skeleton, the Thi has an excellent electron transport performance, and the Schiff base substance can be used for preparing the phenanthroline-based Schiff base derivative. The two are combined to synthesize a novel electron mediator (PT) with good electron transmission performance and high stability. The preparation method is simple, efficient and low in cost, the current in the solution to be detected is tested through a chronoamperometry, and the concentration of the catechol in the solution to be detected is obtained according to the linear relation between the concentration of the catechol and the current. According to the invention, PT is used as an electron transporter, the composite material is formed by loading laccase through PT to serve as a catechol electrochemical sensing catalyst, the composite material shows excellent electrochemical sensing performance, catechol is detected under the constant overpotential condition of 0.23 V (vs.SCE), the lowest detection lower limit is 0.531 [mu] M, and the linear response range is 1-1000 [mu] M.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical sensing technology, and specifically to a preparation method and application of a phenanthroline-based Schiff base derivative. Background Art

[0002] With the continuous development of the economy, some negative impacts brought about by social development, such as environmental pollution, food safety, drug abuse, disease transmission, etc., pose a huge threat to people's health. People pay more and more attention to the safety issues of food, medicine, and the environment. Therefore, the detection of early disease markers and related pollutants in the environment has become crucial. An electrochemical biosensor is a sensor that combines biomolecules with electrochemical detection. The core lies in the combination of biorecognition and electrochemical signal conversion, and the biomolecules are identified and detected by detecting the changes in electrochemical reactions. This method has many advantages, such as low price, simple device, high sensitivity, and the ability to measure the changes of the analyte online. Therefore, it has practical application value and is easy to commercialize.

[0003] In recent years, researchers have done a lot of research work in improving the performance of sensors such as specificity and sensitivity. The research focus is mainly on improving the receiver of the sensor, thereby improving the specificity or sensitivity to the target analyte to be measured. In this research work, Schiff base polymers have attracted extensive attention due to their high stability, two-dimensional (2D) layered structure close to the single-atom thickness, functional diversity, and controllability. However, many COF materials synthesized from Schiff bases have poor conductivity. Researchers usually choose to add highly conductive additives such as gold nanoparticles and carbon nanotubes to improve their electrochemical performance. Therefore, this research selects substances with excellent electron transport performance and a supporting framework for synthesis to improve the application of Schiff base polymers in electrochemical sensing.

[0004] Due to the various electrochemical activities associated with the heteroaromatic nucleus, the electron-donating properties of appropriate nitrogen (sulfur) heteroatoms, good hole transport ability, and low ionization energy, phenothiazine dyes have great application potential in electrochemical (bio) sensors. Among them, thionine in the phenothiazine family has an amino group that can participate in the Schiff base reaction and also has electron transport performance, showing promise for the creation of reagentless biosensors. However, biosensors based on such redox-active polymers of thionine are characterized by a weak connection between the polymer and the working electrode surface, which results in a decrease in electron transfer efficiency. o-Phenanthroline-derived ligands and their complexes have good conjugation. o-Phenanthroline has a unique rigid planar structure with a tricyclic conjugation. The electron cloud density of the nitrogen atoms on its aromatic ring increases, enhancing the electron transfer performance, making o-phenanthroline an excellent and stable π-electron acceptor. Due to the presence of up to 10 modifiable sites on its ring, o-phenanthroline has numerous derivatives. PDL has the structural properties of the o-phenanthroline family and can be used for the pyridine N site for metal coordination. The two aldehyde groups at the 2- and 9-positions are almost coplanar with the rigid phenanthroline moiety. Additionally, there is an advantage in using PDL for the Schiff base reaction, that is, the Schiff base formed by aromatic aldehydes with an effective conjugation system is more stable than the Schiff base formed by aliphatic aldehydes.

[0005] To solve the problems existing in the prior art, the present invention provides a preparation method and application of an o-phenanthroline-based Schiff base derivative. Summary of the Invention

[0006] The object of the present invention is to provide a preparation method and application of an o-phenanthroline-based Schiff base derivative to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: A preparation method of an o-phenanthroline-based Schiff base derivative, including the following method steps:

[0008] Step 1: Dissolve 1,10-phenanthroline-2,9-dicarboxaldehyde (PDL) in a mixed solvent of N,N-dimethylacetamide (DMA) and 1,4-dioxane (Diox) until a pale yellow solution is formed;

[0009] Step 2: Dissolve thionine (Thi) in a mixed solvent of N,N-dimethylacetamide and 1,4-dioxane;

[0010] Step 3: Add the Thi solution obtained in Step 2 to the PDL solution obtained in Step 1 through a syringe and a filter membrane;

[0011] Step 4: Transfer the mixed solution obtained in Step 3 to a polytetrafluoroethylene-lined bottle, place the lined bottle in a reaction kettle, and transfer it to an oven for hydrothermal reaction;

[0012] Step 5: Centrifuge, dry, and grind the solution obtained in Step 4 to obtain a red-brown product, phenanthroline-based Schiff base derivative PT;

[0013] Step 6: Disperse PT, single-walled carbon nanotubes (SWCNT), and laccase (Lac) in water to form a dispersion. Then, drop-coat the dispersion on the surface of a glassy carbon electrode and dry it. Subsequently, slowly drop-coat the lapnoite solution on the electrode surface to seal the sample, and dry it at room temperature to prepare a sensor with a surface-modified PT-C / L composite material;

[0014] Step 7: Using the chronoamperometry method and a three-electrode system, with a platinum wire electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and a sensor with a surface-modified PT-C / L composite material as the working electrode, measure the current of the solution to be tested. According to the linear relationship between the catechol concentration and the current, calculate the catechol concentration in the solution to be tested.

[0015] Preferably, in Step 1, the concentration range of PDL is 6.0 - 9.0 mg / mL, and the volume ratio of DMA to Diox is 1:1.

[0016] Preferably, in Step 2, the concentration range of Thi is 15.0 - 20.0 mg / mL, and the volume ratio of DMA to Diox is 1:1.

[0017] Preferably, the filter membrane used in Step 3 is a nylon filter membrane.

[0018] Preferably, in Step 4, the temperature of the hydrothermal reaction ranges from 100 - 120 °C, and the reaction time is 48 - 72 h.

[0019] Preferably, the washing solvent used for centrifugation in Step 5 is N,N-dimethylformamide (DMF).

[0020] Preferably, in Step 6, the concentrations are 2 mg / mL PT, 0.5 mg / mL SWCNT, and 3 mg / mL Lac.

[0021] Preferably, in Step 7, the test conditions are as follows: the buffer solution for electrochemical testing is 0.1 M PBS solution with pH = 7.0, the scanning rate is 10 mV / s, the gas atmosphere is oxygen, the test voltage range is -0.2 to +0.6 V vs. SCE, the starting potential for the current-time response curve test is 0.23 V vs. SCE, and the rotation rate of the working electrode is 400 rpm.

[0022] Preferably, the amino group of Thi and the aldehyde group of PDL are used for the amine-aldehyde condensation reaction to form a Schiff base derivative, aiming to combine Thi with good electron transfer performance and PDL with excellent planar structure, so as to synthesize a novel electron mediator with high conjugation and planar structure.

[0023] Preferably, an application of a phenanthroline-based Schiff base derivative, wherein the phenanthroline-based Schiff base derivative is used as a novel electron mediator-supported catalytic substance.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) The present invention synthesizes a Schiff base substance by the amine-aldehyde condensation reaction between 1,10-phenanthroline-2,9-dicarboxaldehyde (PDL) and thionine (Thi). PDL has an excellent carbon skeleton, and Thi has excellent electron transport performance. By combining the two, a novel electron mediator with good electron transport performance and high stability is synthesized.

[0026] (2) The preparation method of the present invention is simple, efficient and low-cost. The current in the test solution is measured by chronoamperometry, and according to the linear relationship between the catechol concentration and the current, the concentration of catechol in the test solution is obtained.

[0027] (3) The present invention uses PT as an electron transfer body, and forms a composite material by loading laccase on PT as a catechol electrochemical sensing catalyst, showing excellent electrochemical sensing performance. Catechol is detected under the condition of a constant overpotential of 0.23 V (vs. SCE), and the lowest detection limit is 0.531 μM, and the linear response range is 1 - 1000 μM. Description of the Drawings

[0028] Figure 1 It is the FT-IR infrared spectrum of the PT-C / L composite material prepared in Example 1;

[0029] Figure 2 It is the scanning electron micrograph of the PT-C / L composite material prepared in Example 1;

[0030] Figure 3 It is the cyclic voltammogram of the PT-C / L composite material prepared in Example 1 after adding catechol;

[0031] Figure 4 It is the sensing detection diagram of the PT-C / L composite material prepared in Example 1 for catechol;

[0032] Figure 5 It is the anti-interference performance and stability diagram of the Cu-N / C composite material prepared in Example 1 for catechol detection. Detailed Embodiments

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0034] Example 1: Step 1: Dissolve 6.0 mg / mL of 1,10-phenanthroline-2,9-dicarboxaldehyde (PDL) in a mixed solvent of N,N-dimethylacetamide (DMA) and 1,4-dioxane (Diox) until a pale yellow solution is formed, denoted as Solution A;

[0035] Step 2: Dissolve 15.0 mg / mL of thionine (Thi) in a mixed solvent of N,N-dimethylacetamide and 1,4-dioxane, denoted as Solution B;

[0036] Step 3: Add Solution B obtained in Step 2 to Solution A obtained in Step 1 through a syringe and a nylon filter membrane, and the resulting mixed solution is denoted as Solution C;

[0037] Step 4: Transfer Solution C obtained in Step 3 to a polytetrafluoroethylene-lined bottle, place the lined bottle in a reaction kettle and transfer it to an oven for hydrothermal reaction. The reaction temperature is 120 °C and the reaction time is 48 h;

[0038] Step 5: Centrifuge, dry, and grind the solution obtained in Step 4 to obtain a red-brown product, phenanthroline-based Schiff base derivative PT;

[0039] Step 6: Disperse PT, single-walled carbon nanotubes (SWCNT), and laccase (Lac) in water to form a dispersion. The concentration of PT in the formed dispersion is 2 mg / mL, the concentration of SWCNT is 0.5 mg / mL, and the concentration of Lac is 3 mg / mL. Then, 15 μL of the dispersion is drop-coated on the surface of a glassy carbon electrode with a diameter of 3 mm, dried, and then 5 μL of lapnoite solution is slowly drop-coated on the electrode surface to seal the sample. After drying at room temperature, a sensor with a surface-modified PT-C / L composite material is prepared;

[0040] Step 7: Using chronoamperometry, with a three-electrode system, a platinum wire electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and a sensor with a surface-modified PT-C / L composite material as the working electrode, in an oxygen atmosphere, add 10 mL of 0.1 M PBS solution with pH = 7.0 to the electrolytic cell, the scanning rate is 10 mV / s, measure the current of the solution to be measured, the test voltage range is -0.2 to +0.6 V vs. SCE, the starting potential for the current-time response curve test is 0.23 V vs. SCE, the rotation rate of the working electrode is 400 rpm, and calculate the catechol concentration in the solution to be measured according to the linear relationship between catechol concentration and current.

[0041] Example 2: Step 1: Dissolve 7.0 mg / mL 1,10-phenanthroline-2,9-dicarboxaldehyde (PDL) in a mixed solvent of N,N-dimethylacetamide (DMA) and 1,4-dioxane (Diox) until a pale yellow solution is formed, denoted as solution A;

[0042] Step 2: Dissolve 16.0 mg / mL thionine (Thi) in a mixed solvent of N,N-dimethylacetamide and 1,4-dioxane, denoted as solution B;

[0043] Step 3: Add the B solution obtained in Step 2 to the A solution obtained in Step 1 through a syringe and a nylon filter membrane, and the resulting mixed solution is denoted as solution C;

[0044] Step 4: Transfer the C solution obtained in Step 3 to a polytetrafluoroethylene-lined bottle, place the lined bottle in a reaction kettle and transfer it to an oven for hydrothermal reaction, the reaction temperature is 120 °C, and the reaction time is 48 h;

[0045] Step 5: Centrifuge, dry, and grind the solution obtained in Step 4 to obtain a red-brown product, phenanthroline-based Schiff base derivative PT;

[0046] Step 6: Disperse PT, single-walled carbon nanotubes (SWCNT), and laccase (Lac) in water to form a dispersion. The concentration of PT in the formed dispersion is 2 mg / mL, the concentration of SWCNT is 0.5 mg / mL, and the concentration of Lac is 3 mg / mL. Then drop 15 μL of the dispersion onto the surface of a glassy carbon electrode with a diameter of 3 mm, dry it, and then continue to slowly drop 5 μL of lapnoite solution onto the electrode surface to seal the sample, and dry it at room temperature to prepare a sensor with a surface-modified PT-C / L composite material;

[0047] Step 7: Using chronoamperometry and a three - electrode system, with a platinum wire electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and a sensor with a surface - modified PT - C / L composite material as the working electrode. In an oxygen atmosphere, add 10 mL of 0.1 M PBS solution with pH = 7.0 to the electrolytic cell. The scanning rate is 10 mV / s. Test the current of the solution to be measured. The test voltage range is - 0.2~+0.6 V vs. SCE. The starting potential for the current - time response curve test is 0.23 V vs. SCE. The rotation rate of the working electrode is 400 rpm. Calculate the catechol concentration in the solution to be measured according to the linear relationship between the catechol concentration and the current.

[0048] Example 3: Step 1: Dissolve 8.0 mg / mL of 1,10 - phenanthroline - 2,9 - dialdehyde (PDL) in a mixed solvent of N,N - dimethylacetamide (DMA) and 1,4 - dioxane (Diox) until a pale yellow solution is formed, denoted as solution A;

[0049] Step 2: Dissolve 17.0 mg / mL of thionine (Thi) in a mixed solvent of N,N - dimethylacetamide and 1,4 - dioxane, denoted as solution B;

[0050] Step 3: Add the B solution obtained in Step 2 to the A solution obtained in Step 1 through a syringe and a nylon filter membrane. The resulting mixed solution is denoted as solution C;

[0051] Step 4: Transfer the C solution obtained in Step 3 to a polytetrafluoroethylene - lined bottle. Place the lined bottle in a reaction kettle and transfer it to an oven for hydrothermal reaction. The reaction temperature is 120 °C and the reaction time is 48 h;

[0052] Step 5: Centrifuge, dry, and grind the solution obtained in Step 4 to obtain a red - brown product, phenanthroline - based Schiff base derivative PT;

[0053] Step 6: Disperse PT, single - walled carbon nanotubes (SWCNT), and laccase (Lac) in water to form a dispersion. In the formed dispersion, the concentration of PT is 2 mg / mL, the concentration of SWCNT is 0.5 mg / mL, and the concentration of Lac is 3 mg / mL. Then, drop 15 μL of the dispersion onto the surface of a glassy carbon electrode with a diameter of 3 mm, dry it, and then slowly drop 5 μL of lapnoite solution onto the electrode surface to seal the sample. After drying at room temperature, a sensor with a surface - modified PT - C / L composite material is prepared;

[0054] Step 7: Using chronoamperometry, with a three-electrode system, a platinum wire electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and a sensor with a surface-modified PT-C / L composite material as the working electrode, in an oxygen atmosphere, add 10 mL of 0.1 M PBS solution with pH = 7.0 to the electrolytic cell, the scanning rate is 10 mV / s, measure the current of the solution to be tested, the test voltage range is -0.2 to +0.6 V vs. SCE, the starting potential for the current-time response curve test is 0.23 V vs. SCE, the rotation rate of the working electrode is 400 rpm, and calculate the catechol concentration in the solution to be tested according to the linear relationship between the catechol concentration and the current.

[0055] Example 4: Step 1: Dissolve 9.0 mg / mL of 1,10-phenanthroline-2,9-dicarboxaldehyde (PDL) in a mixed solvent of N,N-dimethylacetamide (DMA) and 1,4-dioxane (Diox) until a pale yellow solution is formed, denoted as Solution A;

[0056] Step 2: Dissolve 18.0 mg / mL of thionine (Thi) in a mixed solvent of N,N-dimethylacetamide and 1,4-dioxane, denoted as Solution B;

[0057] Step 3: Add the B solution obtained in Step 2 to the A solution obtained in Step 1 through a syringe and a nylon filter membrane, and the resulting mixed solution is denoted as Solution C;

[0058] Step 4: Transfer the C solution obtained in Step 3 to a polytetrafluoroethylene-lined bottle, place the lined bottle in a reaction kettle and transfer it to an oven for hydrothermal reaction, the reaction temperature is 120 °C, and the reaction time is 48 h;

[0059] Step 5: Centrifuge, dry, and grind the solution obtained in Step 4 to obtain a red-brown product, phenanthroline-based Schiff base derivative PT;

[0060] Step 6: Disperse PT, single-walled carbon nanotubes (SWCNT), and laccase (Lac) in water to form a dispersion. The concentration of PT in the formed dispersion is 2 mg / mL, the concentration of SWCNT is 0.5 mg / mL, and the concentration of Lac is 3 mg / mL. Then drop 15 μL of the dispersion onto the surface of a glassy carbon electrode with a diameter of 3 mm and dry it. Then continue to slowly drop 5 μL of lapnoite solution onto the electrode surface to seal the sample, and dry it at room temperature to prepare a sensor with a surface-modified PT-C / L composite material;

[0061] Step 7: Using chronoamperometry and a three - electrode system, with a platinum wire electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and a sensor with a surface - modified PT - C / L composite material as the working electrode, in an oxygen atmosphere, add 10 mL of 0.1 M PBS solution with pH = 7.0 to the electrolytic cell. The scanning rate is 10 mV / s. Test the current of the solution to be measured. The test voltage range is - 0.2~+0.6 V vs. SCE. The starting potential for the current - time response curve test is 0.23 V vs. SCE. The rotation rate of the working electrode is 400 rpm. Calculate the catechol concentration in the solution to be measured according to the linear relationship between the catechol concentration and the current.

[0062] Example 5: Step 1: Dissolve 9.0 mg / mL of 1,10 - phenanthroline - 2,9 - dialdehyde (PDL) in a mixed solvent of N,N - dimethylacetamide (DMA) and 1,4 - dioxane (Diox) until a pale yellow solution is formed, denoted as solution A;

[0063] Step 2: Dissolve 20.0 mg / mL of thionine (Thi) in a mixed solvent of N,N - dimethylacetamide and 1,4 - dioxane, denoted as solution B;

[0064] Step 3: Add the B solution obtained in Step 2 to the A solution obtained in Step 1 through a syringe and a nylon filter membrane. The resulting mixed solution is denoted as solution C;

[0065] Step 4: Transfer the C solution obtained in Step 3 to a polytetrafluoroethylene - lined bottle. Place the lined bottle in a reaction kettle and transfer it to an oven for hydrothermal reaction. The reaction temperature is 120 °C and the reaction time is 72 h;

[0066] Step 5: Centrifuge, dry, and grind the solution obtained in Step 4 to obtain a red - brown product, phenanthroline - based Schiff base derivative PT;

[0067] Step 6: Disperse PT, single - walled carbon nanotubes (SWCNT), and laccase (Lac) in water to form a dispersion. In the formed dispersion, the concentration of PT is 2 mg / mL, the concentration of SWCNT is 0.5 mg / mL, and the concentration of Lac is 3 mg / mL. Then, drop 15 μL of the dispersion onto the surface of a glassy carbon electrode with a diameter of 3 mm and dry it. Then, slowly drop 5 μL of lapnoite solution onto the electrode surface to seal the sample. After drying at room temperature, a sensor with a surface - modified PT - C / L composite material is prepared;

[0068] Step 7: Using chronoamperometry, with a three-electrode system, a platinum wire electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and a sensor with surface-modified PT-C / L composite material as the working electrode. In an oxygen atmosphere, add 10 mL of 0.1 M PBS solution with pH = 7.0 to the electrolytic cell, the scanning rate is 10 mV / s, measure the current of the solution to be tested, the test voltage range is -0.2 to +0.6 V vs. SCE, the starting potential for the current-time response curve test is 0.23 V vs. SCE, and the rotation rate of the working electrode is 400 rpm. Calculate the concentration of catechol in the solution to be tested according to the linear relationship between the catechol concentration and the current.

[0069] Figure 1 FT-IR infrared spectrogram of the PT-C / L composite material prepared in Example 1. It can be seen that the C=O stretching vibration in the aldehyde group is at 1696 cm-1, and the intensity of the C=O stretching vibration in the synthesized product weakens. The non-negligible broadband in the region of 2300 - 3300 cm-1 can correspond to aliphatic C-H, aromatic C-H, and N-H stretching vibrations in order of decreasing wavenumber, and the intensity of the N-H stretching vibration weakens. The peak around 1620 cm–1 can be attributed to the stretching vibration of the C=N double bond of thionine and PDLTHI.

[0070] Figure 2 Scanning electron micrograph of the PT-C / L composite material prepared in Example 1. From this SEM image, it can be observed that the material mainly exists in the form of irregular block aggregates, the surface of the block is rough and shows a certain degree of layered or flaky stacking structure. Based on the speculation of the strong π-π interaction that may occur in the phenanthroline planar skeleton, the stacking effect between molecules leads to the formation of these irregular large particles. The size of the clusters in the image is about micron-level, and the surface has many protrusions and depressions, indicating the existence of multi-level stacking or local aggregation between particles. Due to the introduction of conjugated structures such as PT (PDL and thionine Schiff base derivatives), a relatively dense ordered packing can be formed at the microscale, while at a larger scale, it appears in the form of looser clusters. Overall, this kind of stacking can not only provide a certain specific surface area, but also enhance the stability of the system through the π-π interaction between molecules, which may have certain structural advantages for subsequent electrochemical or optoelectronic performance applications.

[0071] Figure 3 Cyclic voltammogram of the PT-C / L composite material prepared in Example 1 after adding catechol. After adding 500 μM catechol, the current intensity increases significantly, indicating that the composite material has good response ability to catechol.

[0072] Figure 4Sensing detection diagram of PT-C / L composite material prepared in Example 1 for catechol. The PT-C / L composite material exhibits excellent electrochemical sensing performance, with a minimum detection limit of 0.531 μM and a linear response range of 1 - 1000 μM.

[0073] Figure 5 Anti-interference performance and stability performance diagram of Cu-N / C composite material prepared in Example 1 for catechol detection. It can be seen that after adding 10 μM catechol aqueous solution. The I-t curve shows an obvious upward trend, that is, the PT-C / L composite material has an obvious catalytic effect on catechol. Subsequently, after sequentially adding 10 mM various cationic, organic molecular, and electroactive substance interferents, no further current change in the i-t curve is observed. After adding the catechol aqueous solution, the i-t curve shows an obvious upward trend again, proving that the PT-C / L composite material has no catalytic effect on the above solution and has excellent anti-interference ability. When catechol is added multiple times, the current is in an increasing state, which indicates that the modified electrode has good selectivity for the catalysis of catechol. The PT-C / L composite material has strong anti-interference for the catalysis of catechol. In the range of 200 - 3000 s after adding 100 μM catechol aqueous solution, the current curve remains stable for a long time, which indicates that the electrode modified with the PT-C / L composite material is not easily detached during the electrocatalytic oxidation process of catechol and has stable performance.

Claims

1. A preparation method of a phenanthroline-based Schiff base derivative, characterized in that, The method comprises the following steps: Step 1: Dissolve 1,10-phenanthroline-2,9-dicarbaldehyde (PDL) in a mixed solvent of N,N-dimethylacetamide (DMA) and 1,4-dioxane (Diox) until a light yellow solution is formed; Step 2: dissolving thionine (Thi) in a mixed solvent of N,N-dimethylacetamide and 1,4-dioxane; Step 3: Add the Thi solution obtained in step 2 into the PDL solution obtained in step 1 through a syringe and a filter membrane; Step 4: Transfer the mixed solution obtained in step 3 to a polytetrafluoroethylene lined bottle, place the lined bottle in a reaction kettle and transfer it to an oven for hydrothermal reaction; Step 5: centrifuging, drying and grinding the solution obtained in step 4 to obtain a reddish brown product, o-phenanthroline Schiff base derivative PT; Step 6: PT, single-walled carbon nanotubes (SWCNT) and laccase (Lac) are dispersed in water to form a dispersion, and then the dispersion is dropwise coated on the surface of the glassy carbon electrode for drying, and then the lapnoite solution is slowly dropwise coated on the electrode surface to seal the sample, and after drying at room temperature, a sensor of the surface-modified PT-C / L composite material is obtained; Step 7: Using the chronoamperometry method, using a three-electrode system, with a platinum wire electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and a sensor with a surface-modified PT-C / L composite material as the working electrode, the current of the test solution is tested, and the catechol concentration in the test solution is calculated based on the linear relationship between the catechol concentration and the current.

2. The preparation method of a phenanthroline-based Schiff base derivative according to claim 1, characterized in that: In the step 1, the concentration range of PDL is 6.0-9.0 mg / mL, and the volume ratio of DMA to Diox is 1:

1.

3. The preparation method of a phenanthroline-based Schiff base derivative according to claim 1, characterized in that: In the step 2, the concentration range of Thi is 15.0-20.0 mg / mL, and the volume ratio of DMA to Diox is 1:

1.

4. The preparation method of a phenanthroline-based Schiff base derivative according to claim 1, wherein: The filter membrane used in step three is a nylon filter membrane.

5. The preparation method of a phenanthroline-based Schiff base derivative according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step 4 is between 100-120° C., and the reaction time is 48-72 hours.

6. The preparation method of a phenanthroline-based Schiff base derivative according to claim 1, characterized in that: The washing solvent used for centrifugation in step 5 is N,N-dimethylformamide (DMF).

7. The preparation method of a phenanthroline-based Schiff base derivative according to claim 1, characterized in that: The concentrations in step six are 2 mg / mL PT, 0.5 mg / mL SWCNT, and 3 mg / mL Lac.

8. The preparation method of a phenanthroline-based Schiff base derivative according to claim 1, characterized in that: In step seven, the test conditions are as follows: the buffer used for the electrochemical test is a 0.1 M PBS solution with a pH of 7.0, the scanning rate is 10 mV / s, the gas atmosphere is oxygen, the test voltage range is -0.2 to +0.6 V vs. SCE, the starting potential of the current-time response curve test is 0.23 V vs. SCE, and the working electrode rotation rate is 400 rpm.

9. The preparation method of a phenanthroline-based Schiff base derivative according to claim 1, characterized in that: The amino group of Thi and the aldehyde group of PDL are used to carry out an amine-aldehyde condensation reaction to form a Schiff base derivative, and Thi and PDL are combined to synthesize a new type of electron mediator with high conjugation and planar structure.

10. Application of a phenanthroline-based Schiff base derivative, characterized in that, The o-phenanthroline Schiff base derivative is obtained by the preparation method described in any one of claims 1 to 9, and the o-phenanthroline Schiff base derivative is used as a novel electron mediator-supported catalytic substance.

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