Thioester-protected ligand, ZnS4 site-connected three-dimensional metal organic framework material, and preparation method and application of thioester-protected ligand and ZnS4 site-connected three-dimensional metal organic framework material

Abstract

The invention discloses a thioester protected ligand, a ZnS4 site connected three-dimensional metal organic framework material as well as a preparation method and application of the thioester protected ligand and ZnS4 site connected three-dimensional metal organic framework material. The ligand takes triphenylene as a main body and thiol protected by an ester group as a substituent group, thioester is coordinated with metal ions while being hydrolyzed in the MOF forming process, the crystallization speed is slowed down, and a triple interspersed metal organic framework with high crystallinity can be obtained; the three-dimensional metal organic framework material has an anion framework property, shows a rapid colorimetric reaction on a positively charged toxic pollutant paraquat, and can be used as a naked eye sensor of paraquat.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal-organic framework functional materials, and particularly relates to a thioester-protected ligand, a three-dimensional metal-organic framework material connected by ZnS 4 sites, and a preparation method and application thereof. Background Art

[0002] Thiol metal-organic frameworks (S-MOFs), porous ordered framework materials formed by coordination bonds composed of thiol-containing organic linkers and metal nodes, have unique advantages such as large specific surface area, high tunability, and well-defined active sites. Moreover, due to the redox activity of electron-diffusing thiolates and the strong interaction with heavy / transition metal centers, S-MOFs usually have rich activity, good electrical conductivity, etc. These characteristics make S-MOFs stand out in a wide range of applications, including semiconductors, photocatalysis, electrocatalysis, energy storage, sensing, heavy metal adsorption, etc.

[0003] Generally, S-MOFs have two types: (1) frameworks composed of metal ions and linkers with carboxyl and thiol groups; (2) planar π-conjugated two-dimensional (2D) networks constructed from soft metal ions and linkers with only thiol groups (such as 2,3,6,7,10,11-hexakis(mercapto)triphenylene, HTT 6- ). On the one hand, the carboxyl group in the thiol linker reduces the electron density of the thiol and slows down the formation of the M-S bond. On the other hand, it reversibly coordinates with the metal center itself to promote the assembly of crystalline S-MOFs, which is suitable for resolving single crystal structures; therefore, it is insightful to obtain three-dimensional (3D) crystallographic analysis of thiol-linked S-MOFs. Summary of the Invention

[0004] For the above reasons, in order to slow down the coordination of higher-crystallinity frameworks and even be applicable to single crystal determination, the first object of the present invention is to provide a thioester-protected ligand, which masks the thiol functional group as a thioester. The ligand not only has laboratory stability but can also be easily deprotected during the assembly process to prolong the coordination process.

[0005] The second object of the present invention is to provide a three-dimensional metal-organic framework material connected by ZnS 4 sites, which is a triple-interpenetrated metal-organic framework with high crystallinity.

[0006] The third object of the present invention is to provide a preparation method of a three-dimensional metal-organic framework material connected by ZnS 4 sites. By selecting a suitable ligand and performing a hydrothermal reaction, controlling the crystallization rate, a triple-interpenetrated metal-organic framework is obtained.

[0007] The fourth object of the present invention is to provide a three-dimensional metal-organic framework material connected by ZnS 4Application of Site-Linked Three-Dimensional Metal-Organic Framework Material in Paraquat Detection.

[0008] The first object of the present invention can be achieved by adopting the following technical solutions:

[0009] A thioester-protected ligand having the structure shown in Formula I:

[0010]

[0011] wherein R is n is 0, 1 or 2.

[0012] The second object of the present invention can be achieved by adopting the following technical solutions:

[0013] A ZnS 4 site-linked three-dimensional metal-organic framework material, comprising a ligand having the structure shown in Formula I and zinc ions,

[0014] wherein each Zn 2+ center chelates with two adjacent sulfur anions of two ligands having the structure shown in Formula I to form a tetrahedral four-coordinate ZnS 4 unit, and each ligand having the structure shown in Formula I is tridentately connected to three ZnS 4 units to form an extended three-dimensional structure.

[0015] Furthermore, the three-dimensional structure has a windmill topological structure; it includes a windmill disk formed by connecting six ligands having the structure shown in Formula I with six ZnS 4 alternately; each ligand having the structure shown in Formula I on the windmill disk extends outward to connect with ten ligands having the structure shown in Formula I including adjacent ligands having the structure shown in Formula I to form windmill blades, and each windmill blade shares 3 ligands having the structure shown in Formula I;

[0016] The dihedral angle between adjacent ligand planes surrounding the windmill disk is 85°, and the dihedral angle between adjacent ligand planes forming the windmill blades is 90°;

[0017] The disk of one windmill is alternately wound with the blades of two other windmills.

[0018] The third object of the present invention can be achieved by adopting the following technical solutions:

[0019] A preparation method of a ZnS 4 site-linked three-dimensional metal-organic framework material, reacting a ligand having the structure shown in Formula I with a divalent zinc ion precursor by solvothermal reaction to obtain the ZnS 4 site-linked three-dimensional metal-organic framework material.

[0020] Further, the divalent zinc ion precursor is an acetic acid, hydrochloric acid, sulfuric acid or nitric acid compound of divalent zinc ions and their hydrates.

[0021] Further, the molar ratio of the monomer of the structure shown in Formula I to the divalent zinc ion precursor is 1:(2.5 - 3.5).

[0022] Further, the solvent for the reaction is a mixed solvent of NaOH methanol solution and ethylenediamine, and the volume ratio of the NaOH methanol solution to ethylenediamine is 1:(0.5 - 2);

[0023] The molar concentration of NaOH in the NaOH methanol solution is 200 - 278 mmol / L –1 .

[0024] Further, the conditions for the solvothermal reaction are:

[0025] The molar volume ratio of the monomer of the structure shown in Formula I to the solvent is (1.5 - 3) μmol:1 mL;

[0026] The reaction temperature is 100 - 120 °C; the reaction time is 12 - 96 h.

[0027] Further, after the reaction, it includes a separation and washing process; after separation, the solid is washed with methanol and dried in vacuum to obtain the three-dimensional metal-organic framework material connected to the ZnS 4 site.

[0028] To achieve the fourth object of the present invention, the following technical solutions can be adopted:

[0029] The application of the three-dimensional metal-organic framework material connected to the ZnS site described in any one of the above in paraquat detection. 4

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. For the thioester-protected ligand of the present application, the thiols connected to the 2,3,6,7,10,11 positions of triphenylene are protected by ester groups. During the formation of MOF as a ligand, triphenylene serves as the basic skeleton, and the thioester hydrolyzes and coordinates with metal ions simultaneously, slowing down the crystallization rate, and a metal-organic framework with high crystallinity can be obtained.

[0032] 2. The three-dimensional metal-organic framework material connected to the ZnS site of the present application has the high conjugate structure of triphenylene and the ZnS 4 site, and has a triple-interpenetrated metal-organic framework, with efficient electron transfer characteristics. 4

[0033] 3. The ZnS of the present application 4 ​​Preparation method of site-connected three-dimensional metal-organic framework material, which controls the coordination connection between ligand and metal ion through ligand hydrolysis, slows down the crystallization rate of MOF formation, and can obtain metal-organic framework with high crystallinity.

[0034] 4. ZnS of the present application 4 The site-connected three-dimensional metal-organic framework material has the property of anionic framework, shows a rapid colorimetric reaction to positively charged toxic pollutant paraquat, and can be used as a naked-eye sensor for paraquat. Description of the drawings

[0035] Figure 1 Crystal diagram of HTT-Zn prepared in the example;

[0036] Figure 2 1H NMR spectrum of HTT-Zn prepared in the example;

[0037] Figure 3 X-ray powder diffraction pattern of HTT-Zn prepared in the example;

[0038] Figure 4 For one Zn 2+ Tetrahedral four-coordination [ZnS4] unit structure diagram formed by each Zn center chelating with adjacent two sulfur anions of two ligands shown in Formula I;

[0039] Figure 5 Topological structure diagram of HTT-Zn prepared in the example;

[0040] Figure 6 Infrared spectrum of HTT-Zn prepared in the example;

[0041] Figure 7 Thermogravimetric curve diagrams of HTT-Zn prepared in the example under nitrogen and air atmospheres respectively;

[0042] Figure 8 X-ray powder diffraction pattern of the residue after thermogravimetric analysis of HTT-Zn-1 prepared in the example;

[0043] Figure 9 Crystal diagram of HTT-Zn prepared in the example after being treated with paraquat;

[0044] Figure 10 Crystal diagrams of HTT-Zn prepared in the example after being treated with paraquat at different concentrations. Detailed implementation manners

[0045] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0046] Existing organic ligands with thiol groups, where the naked thiol ligands are prone to oxidation and deterioration in air and are not suitable for long-term storage in air; and the strong coordination of HTT 6- chelates the metal center very quickly, resulting in the fact that this type of S-MOF usually adopts a two-dimensional planar network connected by metal double MS 4 nodes, and the obtained S-MOF usually has very poor crystallinity. In order to slow down the coordination of a higher crystallinity framework and even be suitable for single crystal determination, the present invention proposes a masking strategy of functionalizing thiol into thioester, which not only has laboratory stability (for example, thiol is more easily oxidized in air), but can also be easily deprotected during the assembly process to prolong the coordination process.

[0047] A thioester-protected ligand has the structure shown in Formula I:

[0048]

[0049] wherein R is n is 0, 1 or 2.

[0050] The thiols connected to the 2, 3, 6, 7, 10, 11 positions of triphenylene are protected by ester groups. During the formation of MOF as a ligand, triphenylene serves as the basic skeleton, and the thioester hydrolyzes while coordinating with metal ions, slowing down the crystallization rate, and a metal-organic framework with high crystallinity can be obtained.

[0051] The thiols of 2,3,6,7,10,11-hexakis(mercapto)triphenylene are protected by ester groups. During the formation of MOF as a ligand, triphenylene serves as the basic skeleton, and the thioester hydrolyzes while coordinating with metal ions, slowing down the crystallization rate, and a metal-organic framework with high crystallinity can be obtained.

[0052] As one of the implementation manners, the ligand with the structure shown in Formula I is prepared by reacting 2,3,6,7,10,11-hexahalotriphenylene with CH 3 SNa and then adding acyl chloride to continue the reaction.

[0053] As one of the implementation manners, 2,3,6,7,10,11-hexabromotriphenylene and CH 3SNa is added to dimethyl ethylene urea (DMEU) under an inert gas atmosphere and reacted at high temperature; after the reaction is completed and cooled, valeryl chloride is added under an inert gas atmosphere, and the reaction is stirred at low temperature. After the reaction is completed, extraction and separation are carried out to obtain the ligand shown in Formula I with n = 3.

[0054] As one of the embodiments, the high-temperature reaction is carried out at 200 - 250 °C for 12 - 36 h; the low-temperature reaction is carried out at 0 - 10 °C for 1 - 3 h.

[0055] As one of the embodiments, the process of extraction and separation is that after the reaction is completed, the mixture is poured into ice water and extracted with toluene; then the combined organic layer is washed with water, dried, and the volatile substances are evaporated under vacuum; the crude product is purified by chromatography (3:1 CH 2 Cl 2 / hexane).

[0056] A three-dimensional metal-organic framework material connected at ZnS 4 sites of the present application includes the ligand shown in Formula I and zinc ions,

[0057] wherein each Zn 2+ center chelates with two adjacent sulfur anions of HTT 6- to form a tetrahedral four-coordinate ZnS 4 unit, and each HTT 6- trifurcately connects with three [ZnS 4 units to form an extended three-dimensional structure.

[0058] Each Zn 2+ center chelates with two adjacent sulfur anions of HTT 6- to obtain a tetrahedral four-coordinate [ZnS 4 unit, rather than the common planar metal-bis(dithiolene) site. [ZnS 4 serves as a secondary building unit (SBU), and each triangular HTT 6- trifurcately connects with three SBUs to form an infinitely extended three-dimensional structure.

[0059] As one of the embodiments, the three-dimensional structure has a windmill topology; it includes a windmill disk formed by alternately connecting 6 HTT 6- with 6 [ZnS 4 ; each HTT 6- on the windmill disk extends outward and connects with ten HTT6 6- including the adjacent HTT - to form windmill blades, and each windmill blade shares 3 HTT 6- ;

[0060] Adjacent HTT6 surrounding the windmill disk - The dihedral angle between the planes is 85°, and the adjacent HTT6 forming the windmill blades - The dihedral angle between the planes is 90°;

[0061] The disk of one windmill is alternately wound with the blades of the other two windmills.

[0062] Viewed along the c-axis, with HTT 6- and Zn 2+ as triangles and rods, the framework can be simplified to a windmill-like topological structure. Adjacent HTT surrounding the windmill disk 6- The dihedral angle between the planes is approximately 85°, while the adjacent HTT 6- The dihedral angle between the planes forming the windmill blades is approximately 90°. And it exhibits a triple interpenetrating structure, that is, the disk of one windmill is alternately wound with the blades of the other two windmills.

[0063] The present invention provides a preparation method of a three-dimensional metal-organic framework material connected by ZnS 4 sites. The ligand of the structure shown in Formula I is subjected to a solvothermal reaction with a divalent zinc ion precursor to obtain the three-dimensional metal-organic framework material connected by ZnS 4 sites.

[0064] The present invention proposes a masking method for functionalizing thiol into thioester. This method not only overcomes the problem that thiol is more easily oxidized in air, making the ligand have laboratory stability; but also can be easily deprotected during the assembly process, and undergoes progressive coordination assembly with Zn(II) salt in an alkaline medium while deprotecting, prolonging the coordination process, and assembling a 3-fold interpenetrating zinc-based S-MOF suitable for crystallographic analysis; the assembly process is as follows:

[0065]

[0066] As one of the embodiments, the divalent zinc ion precursor is an acetic acid, hydrochloric acid, sulfuric acid or nitric acid compound of divalent zinc ion and its hydrate. Preferably, the divalent zinc ion precursor is zinc acetate hydrate Zn(OAc) 2 ·2H 2 O.

[0067] As one of the embodiments, the molar ratio of the monomer of the structure shown in Formula I to the divalent zinc ion precursor is 1:(2.5 - 3.5).

[0068] As one of the embodiments, the reaction solvent is a mixed solvent of NaOH methanol solution and ethylenediamine, and the volume ratio of the NaOH methanol solution to ethylenediamine is 1:(0.5 - 2);

[0069] The molar concentration of NaOH in the NaOH methanol solution is 200 - 278 mmol / L –1 NaOH provides an alkaline environment, which is beneficial to promoting the hydrolysis of the ligand alcohol ester group and enabling the subsequent coordination reaction to occur. Considering the solubility problem of NaOH, a NaOH methanol solution is used; while ethylenediamine is an organic base, on the one hand, it serves as an organic solvent, and on the other hand, it can coordinate with the metal to regulate the pore size.

[0070] As one of the implementation modes, the conditions for the solvothermal reaction are as follows:

[0071] The molar volume ratio of the monomer with the structure shown in Formula I to the solvent is (1.5 - 3) μmol:1 mL;

[0072] The reaction temperature is 100 - 120 °C; the reaction time is 12 - 96 h.

[0073] As one of the implementation modes, the reaction includes a separation and washing process; after separation, the solid is washed with methanol and dried in vacuum to obtain the ZnS 4 Three-dimensional metal-organic framework material connected by the site.

[0074] The following is further illustrated with specific examples.

[0075] Example 1

[0076] Load 2,3,6,7,10,11 - hexabromotriphenylene (0.216 g, 0.3 mmol) and CH 3 SNa (0.664 g, 9.0 mmol) into a 50 mL Schlenk flask; then evacuate the flask and backfill it multiple times with N 2 on the Schlenk pipeline; transfer DMEU (anhydrous, bubbled with nitrogen, 10 ml) into the flask through a sleeve; then stir the reaction mixture at 240 °C for 48 h; let the mixture cool naturally to room temperature, then cool it in an ice bath to 0 °C, and inject valeryl chloride (1.24 ml, 12.6 mmol) under nitrogen; stir at 0 °C for 2 h, pour the mixture into 50 ml of ice water, and extract with 3 - 30 ml of toluene; then wash the combined organic layer with water (4 × 30 ml), dry it with MgSO 4 and evaporate the volatile substances in vacuum; the product (black solid) is purified by chromatography (3:1 CH 2 Cl 2 / hexane) to obtain an off-white solid, which is 2,3,6,7,10,11 - hexakis(butyrylthio)triphenylene.

[0077] Example 2

[0078] The difference from Example 1 is that propionyl chloride is used, and the ligand obtained is 2,3,6,7,10,11 - hexakis(propionylthio)triphenylene.

[0079] Example 3

[0080] The difference from Example 1 is that butyryl chloride is used, and the ligand obtained is 2,3,6,7,10,11 - hexakis(butyrylthio)triphenylene.

[0081] Example 4

[0082] 30 μmol of 2,3,6,7,10,11 - hexakis(acetylthio)triphenylene prepared in Example 1 was added to a 25 mL Schlenk tube, and the tube was evacuated and filled with nitrogen three times; 7 mL of a dry NaOH methanol solution with a concentration of 278 mmol L –1 was bubbled with nitrogen for 5 min and then injected into the Schlenk tube; then, the mixture was ultrasonically treated until 2,3,6,7,10,11 - hexakis(pentanoylthio)triphenylene was completely dissolved; 7.0 mL of an ethylenediamine solution containing 75 μmol of Zn(OAc) 2 ·2H 2 O was bubbled with N 2 for 5 min and then added to the Schlenk tube; the resulting mixture was heated in an oven at 120 °C for 48 h, then naturally cooled to room temperature to obtain block - shaped crystals; the crystals were filtered, washed with methanol, and vacuum - dried at room temperature to obtain the three - dimensional metal - organic framework material connected at the ZnS 4 sites, named HTT - Zn, and the crystal diagram is as Figure 1 shown.

[0083] About 5 mg of HTT - Zn was weighed in a centrifuge tube, deuterated dimethyl sulfoxide and three drops of deuterated hydrochloric acid were added, and the mixture was ultrasonically treated until the crystals were completely dissolved, then centrifuged, and the supernatant was subjected to proton nuclear magnetic resonance detection. The proton nuclear magnetic resonance spectrum is as Figure 2 shown, where the peak at a chemical shift of 3.05 ppm is the peak of ethylenediamine, thus proving that HTT - Zn contains ethylenediamine molecules.

[0084] Example 5

[0085] 30 μmol of 2,3,6,7,10,11 - hexakis(pentanoylthio)triphenylene prepared in Example 2 was added to a 25 mL Schlenk tube, and the tube was evacuated and filled with nitrogen three times; 14 mL of a dry NaOH methanol solution with a concentration of 278 mmol L –1 was bubbled with nitrogen for 5 min and then injected into the Schlenk tube; then, the mixture was ultrasonically treated until 2,3,6,7,10,11 - hexakis(pentanoylthio)triphenylene was completely dissolved; the solution containing 105 μmol of ZnSO4 6 mL of ethylenediamine solution was bubbled with N 2 for 5 min, and then added into a Schlenk tube; the obtained mixture was heated in an oven at 110 °C for 12 h, and then naturally cooled to room temperature to obtain bulk crystals; the crystals were filtered, washed with methanol, and vacuumed at room temperature to obtain the ZnS 4 site-connected three-dimensional metal-organic framework material.

[0086] Example 6

[0087] 30 μmol of 2,3,6,7,10,11-hexakis(hexadecanoylthio)triphenylene prepared in Example 3 was added into a 25 mL Schlenk tube, and the tube was evacuated and filled with nitrogen three times; 3 mL of a dry NaOH methanol solution with a concentration of 278 mmol L –1 was bubbled with nitrogen for 5 min, and then injected into the Schlenk tube; then, the mixture was ultrasonically treated until 2,3,6,7,10,11-hexakis(hexadecanoylthio)triphenylene was completely dissolved; 7.0 mL of an ethylenediamine solution containing 90 μmol of ZnCl 2 was bubbled with N 2 for 5 min, and then added into the Schlenk tube; the obtained mixture was heated in an oven at 100 °C for 96 h, and then naturally cooled to room temperature to obtain bulk crystals; the crystals were filtered, washed with methanol, and vacuumed at room temperature to obtain the ZnS 4 site-connected three-dimensional metal-organic framework material.

[0088] Test example:

[0089] (1) X-ray powder diffraction test was performed on HTT-Zn prepared in Example 4; Rietveld refinement was carried out as Figure 3 shown; the crystallographic parameters and results of HTT-Zn are shown in Table 1.

[0090] Table 1 Crystallographic parameters and results of HTT-Zn

[0091]

[0092]

[0093] a R 1 = ∑(|F 0 | – |F c |) / ∑|F 0 |;

[0094] Single crystal X-ray diffraction was used to analyze HTT-Zn. The crystal data showed that HTT-Zn adopted a hexagonal crystal system with a space group of P63 / m, with lattice parameters of α = β = 90°, γ = 120°. Each Zn 2+ center is chelated with two adjacent sulfur anions of HTT 6- to obtain a tetrahedral four-coordinated [ZnS 4 unit (as shown in Figure 4 ), rather than the common planar metal-bis(dithiolene) site [MS 4 . [MS 4 serves as a secondary building unit (SBU), and each triangular HTT 6- is triconnected with three SBUs to form an infinitely extended three-dimensional structure. Observed along the c-axis, with HTT 6- and Zn 2+ as triangles and rods, the framework can be simplified to a windmill-like topological structure, as shown in Figure 5 . The dihedral angle between adjacent HTT 6- planes surrounding the windmill disk is approximately 85°, while the dihedral angle between adjacent HTT 6- planes forming the windmill blades is approximately 90°, as shown in Figure 5 a. It should be noted that HTT-Zn exhibits a triple interpenetrating structure, that is, the disk of one windmill is alternately intertwined with the blades of the other two windmills, as shown in Figure 5 b and Figure 5 c.

[0095] From Figure 3 the X-ray powder diffraction test results, the two values of R p = 3.96% and R wp = 2.49% are both less than 5%, indicating that the error between the experimental and simulated results is small, that is, the phase purity of the synthesized HTT-Zn is good.

[0096] (2) Elemental analysis was performed on the HTT-Zn prepared in Example 4. The measured contents of the elements were C (33.63%), H (3.42%), N (6.54%). According to Figure 2 the hydrogen spectrum, it was proved that there were free ethylenediamine molecules. Using ethylenediamine for molecular formula fitting, the molecular formula of HTT-Zn could be fitted as Zn 3 (C 18 H 6 S 6 ) 2 (Na) 6 (C 2 H 8 N 2 ) 3.6 (H 2 O) 9, The elemental analysis content calculated from this molecular formula is C (33.65%), H (3.84%), N (6.54%). Compared with the test results, the simulation error is within the normal range, indicating that the fitting result is reliable. At the same time, the fitted molecular formula also conforms to the results of single crystal testing.

[0097] (3) Infrared spectrum analysis was performed on HTT-Zn prepared in Example 4. The infrared spectrum is as Figure 6 shown.

[0098] From Figure 6 the infrared spectrum, it can be observed that the stretching vibration absorption peaks of alkanes at 2957 cm -1 , 2926 cm -1 , 2874 cm -1 and the C=O stretching vibration absorption peak at 1702 cm -1 in 2,3,6,7,10,11-hexakis(acetylthio)triphenylene basically disappear in HTT-Zn, indicating that the thioester has hydrolyzed and coordinated with zinc. The remaining peaks in the range of 2850–3000 cm –1 in HTT-Zn are the -CH 2 vibration peaks on the ethylenediamine molecule, further indicating the successful synthesis of HTT-Zn.

[0099] (4) Thermogravimetric analysis tests were performed on HTT-Zn prepared in Example 4 under nitrogen and air atmospheres respectively. The thermogravimetric curves are as Figure 7 shown; X-ray powder diffraction tests were performed on the powder after thermogravimetric treatment; the X-ray powder diffraction patterns are as Figure 8 shown.

[0100] From the thermogravimetric analysis Figure 7 it can be seen that HTT-Zn has a small weight loss before 200 °C, mainly due to the loss of guest molecules in the pores, such as water molecules; during the period of 200 - 500 °C, the weight loss of HTT-Zn is large, mainly due to the decomposition of the ligand, indicating that the thermal stability of HTT-Zn is about 200 °C; during the period of 500 - 900 °C, the sample weight loss is slow, mainly due to the further decomposition of a small amount of residual organic matter or carbon material; after performing thermogravimetric testing on HTT-Zn in an air atmosphere, the residue was analyzed by powder X-ray diffraction. As Figure 8 shown, it was found that its pattern highly coincides with the pattern of ZnO, indicating that the residue is zinc oxide.

[0101] Test Example:

[0102] Pick a few grains from the HTT-Zn crystals immersed in the MeOH solution into a petri dish (diameter: 35 mm; depth: 10 mm). After sucking out the MeOH with a paper towel or filter paper, drop a few drops of aqueous solution of paraquat diiodide (PDI) on the crystals; observe through a microscope or with the naked eye, and the results are as Figure 9 shown; at the same time, conduct sensing experiments with paraquat at different concentrations of 1000 ppm, 100 ppm, and 10 ppm, and the results are as Figure 10 shown.

[0103] From Figure 9 it can be seen that after dropping the aqueous solution of paraquat diiodide (PDI) on the HTT-Zn crystals, the color of the HTT-Zn crystals changed significantly from yellow to black. And from Figure 10 it can be seen that as the concentration of paraquat increases, the degree of blackening of the HTT-Zn crystals becomes heavier; this is because the anion framework of the HTT-Zn crystals has an electrostatic effect on the positive charge in paraquat. Therefore, when the HTT-Zn crystals come into contact with paraquat diiodide (PDI), HTT-Zn shows a significant response to paraquat, and as the concentration of paraquat increases, the degree of change of HTT-Zn from yellow to black deepens. It shows that HTT-Zn plays an important role in the sensing of paraquat.

[0104] In summary, the present invention provides a thioester-protected ligand, a three-dimensional metal-organic framework material connected by ZnS 4 sites, and its preparation method and application. Using triphenylene as the main body and thioalcohol protected by an ester group as a substituent, during the formation of the MOF, the thioester hydrolyzes and coordinates with metal ions while slowing down the crystallization rate, and a three-fold interpenetrated metal-organic framework can be obtained, which has high crystallinity. The three-dimensional metal-organic framework material has the property of an anion framework and shows a rapid colorimetric reaction to the positively charged toxic pollutant paraquat, and can be used as a naked-eye sensor for paraquat.

[0105] The above embodiments are only the preferred embodiments of the present invention, and the scope of protection of the present invention cannot be limited by this. Any non-substantive changes and substitutions made by those skilled in the art on the basis of the present invention belong to the scope of protection required by the present invention.

Claims

1. A thioester-protected ligand, characterized in that: It has the structure shown in formula I: Where R is n is 0, 1 or 2.

2. A three-dimensional metal organic framework material connected by ZnS4 sites, characterized in that: It comprises a ligand having a structure shown in formula I and a zinc ion, Each Zn 2+ The center chelates with two adjacent sulfur anions of the two structural ligands shown in formula I to form a tetrahedral four-coordinated ZnS4 unit, and each structural ligand shown in formula I is trifurcatedly connected with three ZnS4 units to form an expanded three-dimensional structure.

3. A ZnS4 site-linked three-dimensional metal organic framework material according to claim 2, characterized in that: The three-dimensional structure is a windmill topology structure; it includes a windmill disk formed by six ligands of the structure shown in formula I connected in sequence with six ZnS4 units; each ligand of the structure shown in formula I on the windmill disk extends outward and is connected with ten ligands of the structure shown in formula I including adjacent ligands of the structure shown in formula I to form a windmill blade, and each windmill blade shares three ligands of the structure shown in formula I; The dihedral angle between adjacent planes of the structure of Formula I surrounding the windmill disk is 85°, and the dihedral angle between adjacent planes of the structure of Formula I forming the windmill blade is 90°; The disk of one windmill is wound alternately with the blades of the other two windmills.

4. A method for preparing a three-dimensional metal organic framework material connected by ZnS4 sites, characterized in that: The ligand with the structure shown in formula I undergoes a solvothermal reaction with a divalent zinc ion precursor to obtain the three-dimensional metal organic framework material with ZnS4 sites connected.

5. The method for preparing a three-dimensional metal organic framework material connected by ZnS4 sites according to claim 4, characterized in that: The divalent zinc ion precursor is an acetic acid, hydrochloric acid, sulfuric acid or nitric acid compound of divalent zinc ion and a hydrate thereof.

6. The method for preparing a three-dimensional metal organic framework material connected by ZnS4 sites according to claim 4, characterized in that: The molar ratio of the monomer of the structure shown in Formula I to the divalent zinc ion precursor is 1:(2.5-3.5).

7. The method for preparing a three-dimensional metal organic framework material connected by ZnS4 sites according to claim 4, characterized in that: The reaction solvent is a mixed solvent of NaOH methanol solution and ethylenediamine, and the volume ratio of the NaOH methanol solution to ethylenediamine is 1:(0.5-2); The molar concentration of NaOH in NaOH methanol solution is 200-278 mmol L –1 .

8. The method for preparing a three-dimensional metal organic framework material connected by ZnS4 sites according to claim 4, characterized in that: The conditions for the solvothermal reaction are: The molar volume ratio of the monomer of the structure shown in Formula I to the solvent is (1.5-3) μmol:1 mL; The reaction temperature is 100-120°C; the reaction time is 12-96h.

9. The method for preparing a three-dimensional metal organic framework material connected by ZnS4 sites according to claim 4, characterized in that: After the reaction, a separation and washing process is included; After separation, the solid is washed with methanol and vacuum dried to obtain the three-dimensional metal organic framework material with ZnS4 sites connected.

10. Use of a three-dimensional metal organic framework material connected by ZnS4 sites as claimed in any one of claims 3 to 9 in the detection of paraquat.

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