A heterocyclic ligand-based zinc-based coordination polymer and a preparation method and application thereof

Abstract

This application belongs to the field of fluorescence sensing technology, specifically relating to a zinc-based coordination polymer based on heterocyclic ligands, its preparation method, and its application. The method involves dissolving 3,7-dibromo-10H-phenthiazide, pyridine-4-boronic acid, and K₂CO₃ in a mixture of DMF and H₂O and stirring until homogeneous. Then, tetrakis(triphenylphosphine)palladium is added, and the mixture is heated under a protective gas under reflux. After the reaction, the solvent is removed, impurities are separated, and the mixture is purified to obtain 3,7-di(4-pyridyl)phenthiazide. This 3,7-dibromo-10H-phenthiazide is then dissolved in a mixture of DMF and H₂O, stirred until homogeneous, and heated to react. After the reaction, the mixture is washed and dried to obtain the zinc-based coordination polymer based on heterocyclic ligands. This invention utilizes the butterfly conformation and electron-donating effect of the ligand molecule 3,7-di(4-pyridyl)phenthiazide, along with the synergistic effect of pyridine's coordination binding ability, to coordinate with zinc ions, constructing a novel material with excellent luminescent properties.

Description

Technical Field

[0001] This application belongs to the field of fluorescence sensing technology, specifically relating to a zinc-based coordination polymer based on heterocyclic ligands, its preparation method, and its application. Background Technology

[0002] Phenothiazine (PTZ) possesses a non-planar "butterfly" structure and, due to its unique intramolecular charge transfer mechanism, is frequently used as a near-infrared fluorescent dye with a red-shifted fluorescence spectrum. Following El-sayed's rule, organic light-emitting molecules containing heteroatoms (such as N and O) are chosen, as the lone pair electrons of these heteroatoms facilitate intersystem crossing and promote the generation of triplet excitons. Pyridyl ligands are organic molecules with a pyridyl ring structure, a six-membered carbon-nitrogen heterocycle in which the nitrogen atom acts as a coordination site, forming stable coordinate bonds with metal ions. These ligands provide coordination sites and endow CPs with specific chemical functions, such as catalytic activity. The diversity and modifiability of pyridyl ligands offer extensive flexibility in designing CPs with customized properties.

[0003] Compared with other environmental pollutant detection methods such as voltammetry and atomic absorption spectrometry, fluorescence analysis has advantages such as short response time, low cost, and simple operation. Therefore, developing fluorescence sensors capable of detection is of great significance. Existing technology has developed a novel three-dimensional Cd-MOF-based fluorescence sensor that can achieve high sensitivity and high selectivity in "off-on" mode for the detection of hexavalent chromium ions and ascorbic acid. Although cadmium (Cd)-based metal-organic frameworks (Cd-MOFs) possess excellent luminescent properties, their application in practical biological systems faces significant challenges due to the biotoxicity of the Cd metal center. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a zinc-based coordination polymer based on heterocyclic ligands, its preparation method, and its application. Specifically, the following technical solution is adopted:

[0005] In a first aspect, the present invention provides a method for preparing a zinc-based coordination polymer based on heterocyclic ligands, comprising the following steps:

[0006] 3,7-Dibromo-10H-phenthiazide, pyridine-4-boronic acid and K2CO3 were dissolved in a mixture of DMF and H2O and stirred until homogeneous. Then tetra(triphenylphosphine)palladium was added and the mixture was heated under reflux under a protective gas. After the reaction was completed, the solvent was removed, impurities were separated and purified to obtain 3,7-di(4-pyridyl)phenthiazide.

[0007] The 3,7-bis(4-pyridyl)phenthiazide and zinc nitrate hexahydrate were dissolved in a mixture of DMF and H2O, stirred until homogeneous, heated to react, washed and dried after the reaction was completed to obtain the zinc-based coordination polymer based on heterocyclic ligands.

[0008] This invention designs and synthesizes a novel phenothiazine derivative ligand, 3,7-bis(4-pyridyl)phenothiazine (PTZpy), which can bind to Zn via the pyridine nitrogen site. 2+ Directed coordination successfully constructed a zinc-based coordination polymer, Zn-PTZpy, exhibiting excellent luminescence properties. Based on the conjugation effect of the phenothiazine fluorophore and pyridine group, a method for detecting S2O4 was developed. 2- and CrO4 2- A fluorescent sensor.

[0009] As a further preferred embodiment, the molar ratio of 3,7-dibromo-10H-phenthiazide, pyridine-4-boronic acid, tetrakis(triphenylphosphine)palladium and K2CO3 is 1.4 mmol: 11.2 mmol: 0.07 mmol: 20 mmol.

[0010] As a further preferred embodiment, the molar ratio of 3,7-bis(4-pyridyl)phenthiazide to zinc nitrate hexahydrate is 0.025 mmol:0.025 mmol.

[0011] As a further preferred embodiment, the temperature of the heating reflux reaction is 100℃-120℃, and the time is 48h-72h.

[0012] As a further preferred embodiment, the heating reaction temperature is 100℃-110℃ and the time is 24 h-48 h.

[0013] As a further preferred embodiment, the volume ratio of DMF to H2O in the DMF and H2O mixture is 3-8:1.

[0014] As a further preferred embodiment, the separation of impurities specifically includes the following steps:

[0015] After the reaction is complete and the solvent is removed, the product is dissolved in a mixture of dichloromethane and water. The two phases are separated, the organic phase is washed, filtered, and rotary evaporated.

[0016] Secondly, the present invention provides a zinc-based coordination polymer based on heterocyclic ligands, which is prepared by the above-described preparation method.

[0017] Thirdly, the present invention provides a fluorescent probe comprising the above-described heterocyclic ligand-based zinc-based coordination polymer.

[0018] Fourthly, the present invention provides the above-mentioned heterocyclic ligand-based zinc-based coordination polymer or the above-mentioned fluorescent probe for detecting S2O4. 2- and CrO4 2- Applications in [the field].

[0019] This invention utilizes zinc (Zn) with excellent biocompatibility. 2+ Using 3,7-bis(4-pyridyl)phenthiazide as the metal center fundamentally solves the biotoxicity problem and significantly broadens the application prospects of the material in fields such as biosensing and imaging. Utilizing the butterfly conformation and electron-donating effect of the ligand molecule 3,7-bis(4-pyridyl)phenthiazide, along with the synergistic effect of pyridine's coordination binding ability, a novel material with excellent luminescent properties is constructed by coordinating with zinc ions. According to experimental data from this invention, the addition of S2O4 to this coordination polymer... 2- The solution will enhance the fluorescence of the mixture solution, possibly by more than 200%, upon addition of CrO4. 2- The solution exhibits a fluorescence quenching effect, with a quenching degree potentially exceeding 90%. Titration experiments demonstrate that this sensor is effective against S2O4. 2- and CrO4 2- With its excellent sensitivity, selectivity, and rapid response, it expands the application of polymers in fields such as biolabeling.

[0020] The beneficial effects of this invention are as follows:

[0021] By cleverly coupling the molecular properties of phenothiazine and pyridine, this invention designs a novel structural material and constructs a fluorescent sensor with both high selectivity and dual response, providing a new strategy for developing more functional CPs materials based on phenothiazine derivatives. The material has a simple synthesis method, uses inexpensive raw materials, and achieves control over reducing (S₂O₄)₂... 2- ) and oxidizing properties (CrO4) 2- The dual-function sensor for anions greatly improves detection efficiency and application potential, and also enhances the detection of S2O4. 2- and CrO4 2- It exhibits good sensitivity, selectivity, and rapid response, and can quickly identify S2O4 in actual polluted water samples. 2- and CrO4 2- This expands the application of polymers in fields such as biomarking. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The image shown is the 1H NMR spectrum of PTZpy.

[0024] Figure 2 The diagram shows the crystal structure of the Zn-PTZpy coordination polymer; where (a) is an asymmetric unit; and (bc) is a three-dimensional structure.

[0025] Figure 3 The photophysical properties of the Zn-PTZpy coordination polymer are shown below; (a) shows the excitation spectrum of PTZpy at 397 nm and the emission spectrum at 519 nm; (b) shows the excitation spectrum of Zn-PTZpy at 397 nm and the emission spectrum at 593 nm; (c) shows the CIE coordinate plot (the inset is the corresponding image under 254 nm UV light irradiation); and (d) shows the lifetime decay curve of Zn-PTZpy.

[0026] Figure 4 The following is a study on the fluorescence sensing performance of Zn-PTZpy: (a) fluorescence selective detection emission diagram of Zn-PTZpy mixed with different compounds; (b) fluorescence selective detection bar chart of Zn-PTZpy mixed with different compounds.

[0027] Figure 5 The process involves gradually adding CrO4 to a Zn-PTZpy suspension. 2- / S2O4 2- Subsequently, the fluorescence intensity changes of Zn-PTZpy are shown in the diagrams (a, c); CrO4 was gradually added to the Zn-PTZpy suspension. 2- / S2O4 2- Stern-Volmer plots of Zn-PTZpy after solution treatment (b, d).

[0028] Figure 6 The diagram shows a schematic of the preparation of zinc-based coordination polymers based on heterocyclic ligands. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] Example 1

[0031] A method for preparing a zinc-based coordination polymer based on heterocyclic ligands, specifically comprising the following steps:

[0032] (1) Preparation of 3,7-bis(4-pyridyl)phenthiazine (PTZpy) ligand

[0033]

[0034] 3,7-Dibromo-10H-phenothiazine (500 mg, 1.4 mmol), pyridine-4-boronic acid (689 mg, 11.2 mmol), and K₂CO₃ (2.72 g, 20 mmol) were dissolved in DMF (80 mL) and H₂O (10 mL), stirred for 15 min, degassed with nitrogen, and then tetra(triphenylphosphine)palladium (809 mg, 0.07 mmol) was added. The mixture was heated to 100 °C under nitrogen protection and refluxed for 72 h. After the reaction was completed, the solvent was removed under vacuum to obtain the product. The product was redissolved in a mixture of dichloromethane and water, and the two phases were separated. The organic phase was washed twice with water. The organic phase was filtered and rotary evaporated to obtain the crude product. The crude product was then purified by silica gel column chromatography using dichloromethane and methanol as eluents to obtain 3,7-bis(4-pyridyl)phenothiazine in 70.6% yield.

[0035] (2) Preparation of zinc-based coordination polymer based on heterocyclic ligands (Zn-PTZpy)

[0036] 0.025 mmol of 3,7-bis(4-pyridyl)phenthiazide (PTZpy) and 0.025 mmol of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) were dissolved in DMF (3 mL) and H2O (1 mL) and stirred for 5 min. The resulting solution was then transferred to a reaction vessel and heated to 100 °C in an oven for 48 h. After the reaction was completed, the solution was washed three times with water and dried in a vacuum drying oven at 60 °C for 24 h to obtain red crystals (Zn-PTZpy).

[0037] The 3,7-bis(4-pyridyl)phenthiazine (PTZpy) ligands and the zinc-based coordination polymer based on heterocyclic ligands (Zn-PTZpy) prepared above were characterized as follows:

[0038] Figure 1The figure shows the 1H NMR spectrum of PTZpy; as can be seen from the figure, the 1H NMR data confirms that the final product is the target product. Besides the broad singlet NH resonance at 9.10 ppm, the six aromatic protons and eight pyridinium protons were accurately calculated in various integrated trajectories. The shifts of the aromatic protons are shown as doublets at δ7.49, δ7.43, and δ6.78, integrated at 2H. The chemical shifts of the eight pyridinium protons are clearly shown as doublets at δ8.55 and δ7.63, integrated at 4H, consistent with the prediction.

[0039] Select Zn-PTZpy coordination polymer crystals with clean, smooth surfaces, no concave areas, and no cracks. Then, at a temperature of 293 K, use SuperNova E G8910B X... X-ray single-crystal diffractometer, using graphite monochromatic Mo Kα (wavelength 0.71013 Å) rays were used to collect diffraction data using a scanning method. All data were corrected for empirical absorption, and the crystal structure was determined using a direct method. Detailed crystal determination data are shown in Table 1, and the crystal structure is shown in [reference needed]. Figure 2 .

[0040] Table 1 Crystallographic data of Zn-PTZpy

[0041]

[0042] Table 1 shows that Zn-PTZpy crystallizes in the orthogonal Pna21 space group. Figure 2 The single-crystal structure diagram of Zn-PTZpy clearly shows the butterfly-shaped spatial configuration of the phenothiazine group. This non-planar structure effectively suppresses π-π stacking interactions, which is beneficial to improving luminescence performance. The asymmetric unit consists of two Zn groups. 2+ It consists of a cation and four PTZpy ligands. The Zn1 and Zn2 centers adopt a tetrahedral coordination geometry, with two N atoms from two pyridinium groups of the PTZpy ligands in tetracoordination. In Zn1 and Zn2, four monodentate pyridinium groups connect the two Zn centers, resulting in a [Zn(C 12 H9NS-C 10 [H8N2)2] unit. Finally, this one-dimensional chain grows infinitely through hydrogen bonds to form a three-dimensional (3D) supramolecular structure.

[0043] Example 2

[0044] A method for preparing a zinc-based coordination polymer based on heterocyclic ligands, specifically comprising the following steps:

[0045] (1) Preparation of 3,7-bis(4-pyridyl)phenthiazine (PTZpy) ligand

[0046] The process is exactly the same as step (1) in Example 1.

[0047] (2) Preparation of zinc-based coordination polymer based on heterocyclic ligands (Zn-PTZpy)

[0048] 0.025 mmol of 3,7-bis(4-pyridyl)phenthiazide (PTZpy) and 0.02 mmol of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) were dissolved in DMF (3 mL) and H2O (1 mL) and stirred for 5 min. The resulting solution was then transferred to a reaction vessel and heated to 100 °C in an oven for 48 h. After the reaction was completed, the solution was washed three times with water and dried in a vacuum drying oven at 60 °C for 24 h to obtain a small amount of red crystals (Zn-PTZpy).

[0049] Example 3

[0050] A method for preparing a zinc-based coordination polymer based on heterocyclic ligands, specifically comprising the following steps:

[0051] (1) Preparation of 3,7-bis(4-pyridyl)phenthiazine (PTZpy) ligand

[0052] The process is exactly the same as step (1) in Example 1.

[0053] (2) Preparation of zinc-based coordination polymer based on heterocyclic ligands (Zn-PTZpy)

[0054] 0.025 mmol of 3,7-bis(4-pyridyl)phenthiazide (PTZpy) and 0.03 mmol of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) were dissolved in DMF (3 mL) and H2O (1 mL) and stirred for 5 min. The resulting solution was then transferred to a reaction vessel and heated to 100 °C in an oven for 48 h. After the reaction was completed, the solution was washed three times with water and dried in a vacuum drying oven at 60 °C for 24 h to obtain a small amount of red crystals (Zn-PTZpy).

[0055] Example 4

[0056] The specific process for investigating the fluorescence properties of PTZpy and Zn-PTZpy is as follows:

[0057] The fluorescence spectra of PTZpy and Zn-PTZpy were measured using steady-state fluorescence, respectively. The results are as follows: Figure 3 As shown, Figure 3 (a) and Figure 3(b) shows the emission peaks of PTZpy and Zn-PTZpy at 520 nm and 516 nm and 594 nm, respectively. Zn-PTZpy may produce two different conformations under different aggregation states, resulting in two stable excited states and thus dual-emission fluorescence. Compared with the ligand, the steady-state solid-state fluorescence of the coordination polymer shows a significant red shift, which is attributed to the coordination of the ligand with the metal ion. Under UV excitation, PTZpy and Zn-PTZpy exhibit completely different emission colors. PTZpy shows cyan emission, while Zn-PTZpy shows orange-red emission. The CIE coordinates of the emission spectra of PTZpy and Zn-PTZpy are (0.374, 0.577) and (0.474, 0.470), respectively, corresponding to yellow and orange-red (…). Figure 3 c). To investigate the luminescent stability of Zn-PTZpy, the fluorescence decay curve of Zn-PTZpy was determined using transient fluorescence, as shown in the figure. Figure 3 As shown in d, the fluorescence lifetime of Zn-PTZpy is 0.87 ns.

[0058] Example 5

[0059] The specific process for investigating the fluorescence response of Zn-PTZpy prepared in Example 1 in common ions is as follows:

[0060] (1) Add 2 mg Zn-PTZpy to 10 mL of water and sonicate for 60 min.

[0061] (2) Prepare solutions of different compounds (CO3) by mixing different types of anions. 2- SO4 2- OH - HPO4 2- AlO2 - SCN - S2O4 2- CO3 2-- H2PO2 - CrO4 2- (c = 1×10) -3 mol / L).

[0062] (3) Take 0.5 mL of anionic compound solution and add it to 4.5 mL of Zn-PTZpy solution for fluorescence testing.

[0063] (4) For fluorescence analysis, the excitation wavelength is set to 397 nm and the emission wavelength is collected from 417 to 700 nm; the excitation and emission slit widths are set to 3 nm and 3 nm, respectively.

[0064] The result is as follows Figure 4The maximum emission wavelength of Zn-PTZpy appears at 495 nm. After adding different ions, it can be clearly seen that only S2O4 exhibits the highest emission wavelength. 2- This causes a significant enhancement in fluorescence; furthermore, only CrO4... 2- This causes significant fluorescence quenching. CN - SCN - HPO4 2- H2PO2 - OH - SO4 2- CO3 2- AlO2 - Under the same conditions, there was no significant effect on Zn-PTZpy. The fluorescence intensity of Zn-PTZpy at 497 nm was compared after titration with different ions. (S2O4) 2- The induced enhancement may reach over 200%, CrO4 2- The induced quenching degree can reach over 90%. Therefore, the above results indicate that Zn-PTZpy effectively quenches S2O4 in common ions. 2- and CrO4 2- It has good selectivity.

[0065] Example 6

[0066] Investigating the effect of Zn-PTZpy prepared in Example 1 on S2O4 2- and CrO4 2- The sensitivity of the detection is determined through the following process:

[0067] S2O4 was added incrementally to 10 mL of aqueous solution of the complex Zn-PTZpy (2 mg / 10 mL). 2- and CrO4 2- Solution (c = 1 × 10) -3 Fluorescence was measured at mol / L, and the results are as follows: Figure 5 a, b, with S2O4 2- and CrO4 2- Gradually increase, (Zn-PTZpy+ S2O4) 2- The luminescence of the solution of (Zn-PTZpy+CrO4) is enhanced. 2- The luminescence of the solution is quenched. The luminescence efficiency is quantitatively described using the Stern-Volmer (SV) expression: I 0 / I =1+ K sv [M]. The quenching curve was observed by gradually increasing the concentration in the range of 0-200 μM. It exhibited a good linear quenching response at low concentrations. CrO4 was detected. 2- of Ksv The value is 3.56 × 10 4 M -1 (Figure and diagram), the calculated LOD is 0.09 μM. For example... Figure 5 As shown in c and b, the S2O4 gradually increases in the range of 0-200 μM. 2- With increasing concentration, the fluorescence of Zn-PTZpy gradually increased, exhibiting a good linear response at low concentrations. Calculations yielded... K sv The value is 6.69 × 10 3 M -1 With an LOD of 0.12 μM, Zn-PTZpy can be used as a detector for S2O4. 2- and CrO4 2- A highly sensitive fluorescence sensor.

[0068] Comparative Example 1

[0069] To investigate the effect of different solvents on the present invention, this embodiment uses "THF" instead of "DMF" for preparation, and specifically includes the following steps:

[0070] (1) Preparation of 3,7-bis(4-pyridyl)phenthiazine (PTZpy) ligand

[0071] The process is exactly the same as step (1) in Example 1.

[0072] (2) Preparation of zinc-based coordination polymer based on heterocyclic ligands (Zn-PTZpy)

[0073] 0.05 mmol of 3,7-bis(4-pyridyl)phenthiazide (PTZpy) and 0.05 mmol of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) were dissolved in THF (3 mL) and H2O (3 mL) and stirred for 10 min. The resulting solution was then transferred to a reaction vessel and placed in an oven to be heated to 120 °C for 24 h. After the reaction was completed, the product was a yellow solution and no solid product was obtained.

[0074] Therefore, it can be seen that changing the solvent (replacing DMF with THF) will not yield the zinc-based coordination polymer (Zn-PTZpy) based on heterocyclic ligands of this invention. This is because the carbonyl oxygen atom in the DMF molecule has a lone pair of electrons, which can interact with zinc ions (Zn... 2+The zinc ion coordinates and occupies a coordination site, forming a "solvated" metal precursor. This process is relatively slow, which helps control the rate of crystal nucleation and growth, thus facilitating the formation of well-structured coordination polymer single crystals. While the oxygen atom in the THF molecule is also a potential coordination site, its coordination ability is much weaker than that of DMF. It cannot effectively form a stable intermediate with zinc ions, leading to an excessively fast reaction rate and the easy formation of amorphous precipitates, thus preventing the preparation of the target crystal Zn-PTZpy.

[0075] Comparative Example 2

[0076] To investigate the influence of the metal source on the present invention, this embodiment replaces "zinc nitrate hexahydrate" with "zinc chloride," specifically including the following steps:

[0077] (1) Preparation of 3,7-bis(4-pyridyl)phenthiazine (PTZpy) ligand

[0078] The process is exactly the same as step (1) in Example 1.

[0079] (2) Preparation of zinc-based coordination polymer based on heterocyclic ligands (Zn-PTZpy)

[0080] 0.05 mmol of 3,7-bis(4-pyridyl)phenthiazide (PTZpy) and 0.05 mmol of zinc chloride (ZnCl2) were dissolved in acetonitrile (3 mL) and H2O (3 mL) and stirred for 5 min. The resulting solution was then transferred to a reaction vessel and heated to 120 °C in an oven for 36 h. After the reaction was completed, the solution was washed three times with water and then dried in a vacuum drying oven at 60 °C for 24 h to obtain a yellow powder.

[0081] Therefore, it can be seen that replacing zinc nitrate hexahydrate with zinc chloride does not yield the heterocyclic ligand-based zinc coordination polymer (Zn-PTZpy) of this invention. This is because NO 3- It is a very weak coordinating anion that exists as an ion pair or very weakly coordinates to the metal center in a monodentate manner in solvents such as H2O or DMF. It is easily replaced by organic ligands (such as PTZpy). - With zinc ions Zn 2+ It has a strong coordination tendency, Cl - It will strongly occupy the coordination sites of zinc ions and compete with the organic ligand PTZpy for coordination with zinc ions.

[0082] Comparative Example 3

[0083] To investigate the effect of solvent ratio and dosage on the present invention, the following steps are specifically included:

[0084] (1) Preparation of 3,7-bis(4-pyridyl)phenthiazine (PTZpy) ligand

[0085] The process is exactly the same as step (1) in Example 1.

[0086] (2) Preparation of zinc-based coordination polymer based on heterocyclic ligands (Zn-PTZpy)

[0087] 0.025 mmol of 3,7-bis(4-pyridyl)phenthiazide (PTZpy) and 0.025 mmol of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) were dissolved in DMF (3 mL) and H2O (3 mL) and stirred for 5 min. The resulting solution was then transferred to a reaction vessel and heated to 100 °C in an oven for 48 h. After the reaction was completed, the solution was washed three times with water and dried in a vacuum drying oven at 60 °C for 24 h to obtain a small amount of flaky red crystals (Zn-PTZpy).

[0088] Therefore, changing the volume ratio of DNF to H2O from 3:1 to 3:3 does not yield the Zn-PTZpy heterocyclic ligand-based coordination polymer of this invention. This is because the significant increase in the water ratio leads to a substantial increase in the polarity of the entire solvent system and a greatly enhanced protonicity. The solubility of many heterocyclic aromatic ligands in strongly polar protic solvents (such as water) decreases drastically. The ligands may dissolve from a molecular state to a colloidal state, or even precipitate, failing to effectively encounter metal ions in solution and undergo ordered self-assembly.

[0089] The embodiments of this application have been described above with reference to the accompanying drawings. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the core ideas of this application. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for preparing a zinc-based coordination polymer based on heterocyclic ligands, characterized in that, Includes the following steps: 3,7-Dibromo-10H-phenthiazide, pyridine-4-boronic acid and K2CO3 were dissolved in a mixture of DMF and H2O and stirred until homogeneous. Then tetra(triphenylphosphine)palladium was added and the mixture was heated under reflux under a protective gas. After the reaction was completed, the solvent was removed, impurities were separated and purified to obtain 3,7-di(4-pyridyl)phenthiazide. The 3,7-bis(4-pyridyl)phenthiazide and zinc nitrate hexahydrate were dissolved in a mixture of DMF and water, stirred until homogeneous, heated to react, and after the reaction was completed, washed and dried to obtain the zinc-based coordination polymer based on heterocyclic ligands. The molar ratio of 3,7-dibromo-10H-phenthiazide, pyridine-4-boronic acid, tetrakis(triphenylphosphine)palladium and K2CO3 was 1.4 mmol: 11.2 mmol: 0.07 mmol: 20 mmol.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the 3,7-bis(4-pyridyl)phenthiazide to zinc nitrate hexahydrate is 0.025 mmol: 0.02 mmol-0.03 mmol.

3. The preparation method according to claim 1, characterized in that, The heating reflux reaction is carried out at a temperature of 100℃-120℃ for a time of 48 h-72 h.

4. The preparation method according to claim 1, characterized in that, The heating reaction is carried out at a temperature of 100℃-110℃ for a duration of 24 h-48 h.

5. The preparation method according to claim 1, characterized in that, The separation of impurities specifically includes the following steps: After the reaction is complete and the solvent is removed, the product is dissolved in a mixture of dichloromethane and water. The two phases are separated, the organic phase is washed, filtered, and rotary evaporated.

6. A zinc-based coordination polymer based on heterocyclic ligands, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. A fluorescent probe, characterized in that, Including the zinc-based coordination polymer based on heterocyclic ligands as described in claim 6.

8. The heterocyclic ligand-based zinc-based coordination polymer according to claim 6 in the detection of S2O4 2- and CrO4 2- Applications in [the context of the text].

9. The fluorescent probe according to claim 7 for detecting S2O4 2- and CrO4 2- Applications in [the context of the text].

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