CN113563601A

CN113563601A - Cation-deficient ZIF porous material and preparation method and application thereof

Info

Publication number: CN113563601A
Application number: CN202110950889.XA
Authority: CN
Inventors: 张文华; 田鑫鑫
Original assignee: Suzhou University
Current assignee: Suzhou University
Priority date: 2021-08-18
Filing date: 2021-08-18
Publication date: 2021-10-29
Anticipated expiration: 2041-08-18
Also published as: CN113563601B

Abstract

The invention provides a cation-deficient ZIF porous material as well as a preparation method and application thereof, belonging to the technical field of functional adsorption materials. The preparation method of the cation-deficient ZIF porous material comprises the following steps: in an organic solvent, mixing and reacting an imidazole compound with methyl iodide to obtain an imidazole-based cationic ligand; and dissolving the obtained imidazolyl cationic ligand and an imidazole compound in water, adding metal salt, uniformly mixing, and standing for reaction to obtain the cation-deficient ZIF porous material. The obtained cation-deficient ZIF porous material is applied to the adsorption of iodine. The synthesis method is simple, low in cost and high in iodine adsorption efficiency.

Description

Cation-deficient ZIF porous material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of functional adsorption materials, and particularly relates to a cation-deficient ZIF porous material and a preparation method and application thereof.

Background

Nuclear energy is used as a green and reliable energy source, and the importance of the nuclear energy is increasingly highlighted with the increase of energy demand worldwide. However, the risk of radioactive nuclear waste being released into the environment is also one of the important issues to be considered for drug management in the nuclear power industry. Among the numerous radioactive elements, radioactive iodine toolsThere are unique exposure problems. Elemental iodine (I)₂) Its isotope is highly mobile due to its extreme sublimation (45 deg.C)¹²⁹I and¹³¹i also presents unique exposure problems.¹²⁹I is an extremely long-lived isotope with a half-life of 1.57X 10⁷Must be captured and reliably stored during their decay, and¹³¹the half-life of I is only 8.02 days, but it needs to be captured immediately, since it is involved in human metabolic processes. Radioactive iodine can cause adverse damage to human metabolic processes. These radioisotopes, upon inhalation or ingestion through the food chain, tend to accumulate in the thyroid gland, release damaging radiation, cause lung cancer, and increase the incidence of cancer.

During the past decades, iodine adsorbents such as silica, activated carbon, zeolites, etc. have been studied. At present, the method commonly used in industry is to impregnate organic amine (such as triethylamine) in porous material (such as activated carbon), the prepared adsorbent has higher affinity and purification effect on radioactive iodine, and the process of capturing iodine is relatively simple. In recent years, some new porous materials, such as Metal-Organic Framework (MOF) and Covalent-Organic Framework (COF), have been proved to have strong adsorption and storage functions of iodine. Meanwhile, the new materials are concerned by the material cavities with adjustable pore channel structure and size, large specific surface area and weak polarity.

For example, HKUST-1(Hong Kong University of science and Technology) has a high specific surface area (1850 m)² g^-1) And size of the pore channel

Can absorb 175wt percent of I at 75-80 ℃ and normal pressure₂(Table 1). However, the material is much higher than I due to the opening size of the pore channel₂(about

) This gives long-term storage of I with weak polarity₂Causing difficulties. In addition, MFM-300(Sr)/MFM-300(Fe)/MFM-300(In) and Zn₃(DL-lac)₂(pybz)₂Etc. also due to the larger opening size of the channels₂Is difficult to store for a long period of time (table 1). Simultaneous MFM-300 series material and Zn₃(DL-lac)₂(pybz)₂The preparation conditions of MOF materials are harsh, and the like, which causes difficulties in the practical application of the materials. Therefore, the synthetic raw materials which are cheap and easy to obtain are selected, and the stable structure I is obtained through mild and green reaction conditions₂The MOF storage material with high storage capacity and long storage time is a key problem to be solved in the practical application of the material.

TABLE 1

Among many MOF materials, ZIF-8(ZIF ═ zeolic imidazole Framework) having a zeolite structure is an ideal I due to its suitable pore size, large specific surface area, high chemical and thermal stability₂A trapping agent. ZIF-8 tetrahedrally coordinated Zn²⁺A three-dimensional lattice structure with sodalite topology linked to 2-methylimidazole (MeIM) ligands (see figure 1 for results). In this structure, the diameter of the beta-ring is

By a diameter of

The six-membered ring pores are connected. The presence of the six-membered ring pore is such that I₂(about

) Can be diffused and effectively sealed. In addition, the smaller quaternary ring holes in the structure do not allow any guest I due to the smaller size₂Into or out of the hole.

For example, the studies by Nenoff and Navrotsky et al found that ZIF-8 pairs I₂Up to a maximum adsorption level of 125wt%, wherein, 25 wt% of I₂Bound to the ZIF-8 surface with the remainder 100 wt.% I₂It is effectively trapped in the pores of ZIF-8 and only released as the frame disintegrates (about 300 ℃). Baek et al replaced MeIM in ZIF-8 with 3-amino-1, 2, 4-triazole ligand (Atz) by means of post-modification, and when the content of Atz reached 61%, the resulting material ZIF8-A61 was conjugated to I₂The adsorption amount of the ZIF-8 can be up to 8.7 times.

Existing materials for radioactivity I₂There are mainly problems or disadvantages in the following aspects of adsorption and storage: (1) low storage (e.g., activated carbon); (2) the material has large pore canal, which is not favorable for long-term storage (such as Zn)₃(DL-lac)₂(pybz)₂) (ii) a (3) The organic ligand for synthesizing MOF materials is high in cost and harsh in synthesis conditions (such as MFM-300 series); (4) i is₂Only as simple substance (I)₂) Form storage, which is not conducive to long-term storage (e.g., ZIF-8); (5) due to non-polarity I₂The binding effect with the adsorbent is weak, the binding site is unstable, the iodine can be further released, and the conventional trapping method is difficult to firmly fix I₂。

Most of the current reports are that anticancer drugs are embedded by utilizing pores of a nano Metal-Organic Framework (nMOF), and the anticancer drugs have the risk of leakage in the transportation process, so that the toxic and side effects of the anticancer drugs are shown, and the anticancer effect is greatly reduced. In addition, most of nmofs are not easy to enter tumor cells, the surface of the nmofs needs to be modified by polyethylene glycol, hyaluronic acid or folic acid, and the modified nmofs can easily pass through phospholipid bilayers to enter cells, which increases the synthesis difficulty and cost. For example, in 2017, in order to wrap anticancer drugs such as adriamycin and verapamil in ZIF-8, the Li subject group modifies folic acid on the surface of ZIF-8, so that folic acid on the surface of ZIF-8 is specifically bound with a folate receptor on the surface of a tumor cell, and thus nanoparticles can easily enter the tumor cell.

Furthermore, due to the limited effectiveness of a single treatment modality in killing tumor cells, a combination of multiple treatment modalities, such as photodynamic therapy and chemotherapy, radiotherapy and chemotherapy, is desirable. For example, in 2019, Zhang group reported that Doxorubicin (DOX) and photosensitizer chlorin e6(Ce6) are embedded in ZIF-8 and reach tumor cells, DOX and Ce6 are released simultaneously, and Ce6 generates active oxygen under the irradiation of a light source at 630nm to realize photodynamic therapy, and at the same time, DOX plays a role in chemotherapy (FIG. 2).

Most of the existing nano particle carrier transport drugs fall off from the carrier when the drugs do not reach the tumor part through simple physical embedding or adsorption, so that the drug loading capacity is reduced. In addition, most nanoparticles have poor biocompatibility and are not easy to pass through the cell membrane of tumor cells, so that the internalization rate of the tumor cells is low. In addition, most nanoparticles do not target tumor cells or organelles, and modification with a targeting functional group is needed, which causes great synthesis difficulty. Meanwhile, since a single treatment mode has low lethality to tumor cells, a combination of multiple treatment modes, such as chemotherapy and photodynamic therapy, is required to achieve high lethality to tumor cells, which results in high synthesis cost.

Aiming at the technical problems in the prior art: the method comprises the problems of tumor cell targeting, tumor toxicity, SiRNA carrying, anticancer drug transportation, nanoparticle synthesis cost and the like, and a novel technical scheme is urgently needed to solve the problems.

Disclosure of Invention

In order to solve the technical problems, the invention provides a cation-deficient ZIF porous material and a preparation method and application thereof. In the invention, N-containing methylation is added in the synthesis process of ZIF-8 to form N⁺-CH₃"group 2-methylimidazole. Only sp in the group²The hybridized N is methylated to form the quaternary ammonium cation, and sp³The hybridized N still retains the NH form, forming-1 valent ions by coordination with Zn under alkaline conditions to balance valences, with the entire ligand in terminal coordination (see fig. 3). I-enriched formation can thus be achieved by constructing 2-methylimidazole based ZIF-8 containing methylated imidazolium cation defects^-The cationic type ZIF-8 of (A),the obtained compound was named ZIF-8⁺-I^-。

A preparation method of a cation-deficient ZIF porous material comprises the following steps:

step (1): in an organic solvent, mixing and reacting an imidazole compound with methyl iodide to obtain an imidazole-based cationic ligand;

step (2): and (2) dissolving the imidazole-based cationic ligand obtained in the step (1) and an imidazole-based compound in water, adding metal salt, uniformly mixing, and standing for reaction to obtain the cation-deficient ZIF porous material.

In one embodiment of the present invention, in the step (1), the organic solvent is one or more selected from tetrahydrofuran, dimethylformamide, dioxane, acetone, dimethyl sulfoxide, methanol, ethanol, acetonitrile, benzene and toluene.

In one embodiment of the present invention, in step (1) and step (2), the imidazole compound is one or more selected from imidazole, benzimidazole, 2-methylimidazole, imidazole-2-carbaldehyde, 2-chloro-imidazole and 2-phenylimidazole.

In one embodiment of the invention, in step (1), the molar ratio of methyl iodide to imidazole compound is 1:1-3: 1.

In one embodiment of the present invention, in the step (1), the reaction time is 8 to 24 hours and the reaction temperature is 55 to 75 ℃.

In one embodiment of the present invention, in step (2), the molar ratio of the imidazolyl cationic ligand to the imidazole based compound is from 1:30 to 1: 20.

In one embodiment of the present invention, in the step (2), the metal salt is one or more of zinc acetate, zinc nitrate, cobalt acetate and cobalt nitrate.

In one embodiment of the invention, in step (2), the molar ratio of the metal salt to the imidazole compound is from 1:40 to 1: 70.

The cation-deficient ZIF porous material prepared by the preparation method is provided.

The cation-deficient ZIF porous material is applied to iodine adsorption.

Compared with the prior art, the technical scheme of the invention has the following advantages:

the cationic material ZIF-8+ -I of the invention^-Successful synthesis of^-Fixed in the hole of the material as an integral part of the material, can continue to be connected with I₂Form I₃ ^-And simultaneously can exert the high-efficiency I of ZIF-8₂The adsorption performance finally achieves the effect of physical and chemical adsorption synergistic adsorption. Formation of cationic ZIF-8 by modification of ZIF-8⁺-I^-The invention successfully avoids I₂By simultaneous adsorption of I₂Conversion into I₃ ^-And the storage stability is greatly improved.

The material prepared by the invention has the advantages of cheap and easily obtained raw materials, green and simple synthesis, I₂Large storage capacity and long storage time.

Cationic ZIF-8 (ZIF-8) having defects synthesized by the present invention⁺-I^-) Can be combined with some anionic anticancer drugs by electrostatic force, which makes the drugs not easy to fall off from the carrier during transportation, and ZIF-8⁺-I^-Is easy to decompose in an acidic tumor environment, so that the medicine can be completely released at a tumor part, thereby realizing a high-efficiency anticancer effect. The positively charged drug carrier can promote the interaction with the negatively charged cell membrane, thereby improving the internalization speed and degree of cancer cells, and the ZIF-8 synthesized in the time⁺-I^-The nano metal organic framework with positive charges can well interact with cell membranes, so that the nano metal organic framework can easily enter tumor cells, and the synthesis steps are simple and the cost is low.

In addition, the present invention is directed to ZIF-8⁺-I^-Was investigated and found to be associated with ZIF-8⁺-I^-The increasing concentration of ZIF-8 was observed as a stepwise decrease in the viability of tumor cells⁺-I^-Has obvious toxicity to tumor cells, so the efficiency of killing the tumor cells by using the nano particles as carriers is increased.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which

FIG. 1 is a schematic diagram of the synthesis and structure of ZIF-8.

FIG. 2 is a schematic of the synthesis of ZIF 8-A61.

FIG. 3 is a ZIF-8 of the present invention⁺-I^-Schematic synthesis of (a).

FIG. 4 is an imidazolyl cationic ligand of the present invention¹H NMR。

FIG. 5 is a ZIF-8 of the present invention⁺-I^-(20:1)、ZIF-8⁺-I^-(30:1) PXRD vs. ZIF-8 three materials.

FIG. 6 is ZIF-8+ -I obtained in example 1 of the present invention^-EDS spectrum of (30: 1).

FIG. 7 is a ZIF-8 of the present invention⁺-I^-(20:1)、ZIF-8⁺-I^-(30:1) with ZIF-8¹Spectrum of H NMR.

FIG. 8 is a ZIF-8 of the present invention⁺-I^-(20:1)、ZIF-8⁺-I^-(30:1) and ZIF-8.

FIG. 9 is ZIF-8 obtained in example 1 of the present invention⁺-I^-(30:1) Infrared absorption Spectrum.

FIG. 10 is a ZIF-8 of the present invention⁺-I^-(20:1)、ZIF-8⁺-I^-(30:1) thermogravimetric curves of the three materials with ZIF-8.

FIG. 11 is a ZIF-8 of the present invention⁺-I^-(20:1)、ZIF-8⁺-I^-(30:1) N of three materials with ZIF-8₂Adsorption and desorption curves.

FIG. 12 is a ZIF-8 of the present invention⁺-I^-(20:1)、ZIF-8⁺-I^-(30:1) and ZIF-8 materials have adsorption curves for iodine in n-hexane.

FIG. 13 is a ZIF-8 of the present invention⁺-I^-(20:1)、ZIF-8⁺-I^-(30:1) with ZIF-8 IIIAdsorption profile of seed material to iodine vapor.

FIG. 14 is a ZIF-8 of the present invention⁺-I^-(20:1)、ZIF-8⁺-I^-(30:1) cytotoxicity test results with ZIF-8 material.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention. The ZIF-8 is prepared according to the document Dalton trans, 2013,42, 11128-11135.

Example 1

1) Synthesis of imidazolyl cationic ligands

First, 2-methylimidazole (411mg, 5mmol) was added to a reaction flask, followed by tetrahydrofuran (20mL) to completely dissolve 2-methylimidazole, finally iodomethane (710mg, 5mmol) was added, and the temperature was raised to 65 ℃ for overnight reaction, after the reaction was completed, a large amount of pale yellow imidazolyl cationic ligand was seen to be precipitated from tetrahydrofuran, the product was centrifuged, and washed with tetrahydrofuran several times to remove excess iodomethane, and dried to obtain the first step product.¹H NMR(400MHz,D₂O) δ 7.36-7.27 (m,2H),3.79(d, J ═ 0.9Hz,3H),2.61(d, J ═ 9.5Hz,3H), the results are shown in fig. 4, and it is seen from the nuclear magnetic data that a single peak with a methyl group at a displacement value of 3.79 is that "N" on 2-methylimidazole is methylated to form "N" in 2-methylimidazole⁺-CH₃"group", thereby demonstrating the synthesis of the desired product.

2)ZIF-8⁺-I^-Synthesis of (2)

2-methylimidazole (1230mg, 15mmol) and imidazolyl cationic ligand (112mg, 0.5mmol) were weighed and completely dissolved in 5mL of deionized water. Weighing zinc acetate (110mg, 0.5mmol) and dissolving in 5mL deionized water, mixing the two solutions thoroughly, standing for 5h to obtain milky white solution, centrifuging (10,000r/min) for 10min, washing with deionized water for three times, and freeze drying to obtain final product ZIF-8⁺-I^-(30:1)。

Example 2

1) Synthesis of imidazolyl cationic ligands

First, 2-methylimidazole (411mg, 5mmol) was added to a reaction flask, followed by tetrahydrofuran (20mL) to completely dissolve 2-methylimidazole, finally iodomethane (710mg, 5mmol) was added, and the temperature was raised to 65 ℃ for overnight reaction, after the reaction was completed, a large amount of pale yellow imidazolyl cationic ligand was seen to be precipitated from tetrahydrofuran, the product was centrifuged, and washed with tetrahydrofuran several times to remove excess iodomethane, and dried to obtain the first step product.

Separately, 2-methylimidazole (1230mg, 15mmol) and imidazolyl cationic ligand (168mg, 0.75mmol) were weighed and completely dissolved in 5mL of deionized water. Weighing zinc acetate (83mg,0.38mmol) and dissolving in 5mL deionized water, mixing the two solutions thoroughly, standing for 5h to obtain milky white solution, centrifuging (10,000r/min) for 10min, washing with deionized water for three times, and freeze drying to obtain ZIF-8 as final product⁺-I^-(20:1)。

Example 3

1) Synthesis of imidazolyl cationic ligands

Firstly, imidazole (341mg, 5mmol) is added into a reaction flask, then dimethylformamide (20mL) is added to completely dissolve the imidazole, finally methyl iodide (710mg, 5mmol) is added, the temperature is raised to 55 ℃ for reaction for 24 hours, after the reaction is finished, a large amount of light yellow imidazolyl cationic ligand is separated from the dimethylformamide, the product is centrifugally separated, and is washed with the dimethylformamide for multiple times to remove excessive methyl iodide, and the product is dried to obtain the first step product.

2)ZIF-8⁺-I^-Synthesis of (2)

Imidazole (1022mg, 15mmol) and imidazolyl cationic ligand (210mg, 1mmol) were weighed and completely dissolved in 5mL of deionized water. Weighing zinc nitrate (89mg, 0.3mmol) and dissolving in 5mL deionized water, mixing the two solutions thoroughly, standing for 5h to obtain milky white solution, centrifuging (10,000r/min) for 10min, washing with deionized water for three times, and freeze-drying to obtain ZIF-8 as final product⁺-I^-(15:1)。

Example 4

1) Synthesis of imidazolyl cationic ligands

Firstly, imidazole-2-formaldehyde (480mg, 5mmol) is added into a reaction bottle, then dimethyl sulfoxide (20mL) is added to completely dissolve the imidazole-2-formaldehyde, finally methyl iodide (1420mg, 10mmol) is added, the temperature is raised to 65 ℃ for reaction for 10 hours, after the reaction is finished, a large amount of light yellow imidazolyl cationic ligand is separated from the dimethyl sulfoxide, the product is centrifugally separated, and is washed by the dimethyl sulfoxide for multiple times to remove excessive methyl iodide, and the product is dried to obtain a first step product.

2)ZIF-8⁺-I^-Synthesis of (2)

Imidazole-2-carbaldehyde (1441mg, 15mmol) and imidazolyl cationic ligand (90mg, 0.38mmol) were weighed and completely dissolved in 5mL of deionized water. Weighing zinc acetate (55mg,0.25mmol) and dissolving in 5mL deionized water, mixing the two solutions thoroughly, standing for 5h to obtain milky white solution, centrifuging (10,000r/min) for 10min, washing with deionized water for three times, and freeze drying to obtain ZIF-8 as final product⁺-I^-(40:1)。

Example 5

1) Synthesis of imidazolyl cationic ligands

First, 2-chloro-imidazole (513mg, 5mmol) was added to a reaction flask, followed by addition of toluene (20mL) to completely dissolve 2-chloro-imidazole, and finally iodomethane (2130mg, 15mmol) was added, and the temperature was raised to 75 ℃ to react for 24 hours, after the reaction was completed, a large amount of pale yellow imidazolyl cationic ligand was seen to be precipitated from toluene, and the product was centrifuged, washed with toluene several times to remove excess iodomethane, and dried to obtain the first step product.

2)ZIF-8⁺-I^-Synthesis of (2)

2-chloro-imidazole (1538mg, 15mmol) and imidazolyl cationic ligand (73mg, 0.3mmol) were weighed and completely dissolved in 5mL of deionized water. Zinc nitrate (60mg, 0.2mmol) was weighed and dissolved in 5mL of deionized water, and finally the two solutions were mixed well and left to stand for 8h to obtain opalCentrifuging the solution (10,000r/min) for 10min, washing with deionized water three times, and freeze-drying to obtain ZIF-8 as final product⁺-I^-(50:1)。

Example 6

1) Synthesis of imidazolyl cationic ligands

First, benzimidazole (591mg, 5mmol) was added into a reaction flask, followed by addition of methanol (20mL) to completely dissolve the benzimidazole, and finally iodomethane (2130mg, 15mmol) was added, and the temperature was raised to 75 ℃ to react for 24 hours, after the reaction was completed, a large amount of pale yellow imidazolyl cationic ligand was seen to be separated from toluene, the product was centrifuged, and washed with toluene several times to remove excess iodomethane, and dried to obtain the first step product.

2)ZIF-8⁺-I^-Synthesis of (2)

Benzimidazole (1772mg, 15mmol) and imidazolyl cationic ligand (78mg, 0.3mmol) were weighed and completely dissolved in 5mL of deionized water. Weighing zinc nitrate (60mg, 0.2mmol) and dissolving in 5mL deionized water, mixing the two solutions thoroughly, standing for 8h to obtain milky white solution, centrifuging (10,000r/min) for 10min, washing with deionized water for three times, and freeze-drying to obtain ZIF-8 as the final product⁺-I^-(50:1)。

Comparative example 1

ZIF-8 was prepared according to the document Dalton trans, 2013,42, 1112811135: 2-methylimidazole (1230mg, 15mmol) was weighed out and dissolved completely in 5mL of deionized water. And weighing zinc acetate (110mg, 0.5mmol) and dissolving in 5mL of deionized water, fully mixing the two solutions, standing for 5h to obtain a milky white solution, performing centrifugal separation (10,000r/min) for 10min, washing with deionized water for three times, and freeze-drying to obtain the final product ZIF-8.

Material characterization

ZIF-8 prepared in example 1⁺-I^-(30:1) ZIF-8 prepared in example 2⁺-I^-(20:1) and ZIF-8 prepared in comparative example 1 were subjected to performance characterization, which included: x-ray powder diffraction (PXRD) (see FIG. 5), EDS Spectroscopy(see FIG. 6), nuclear magnetic resonance (see FIG. 7), Scanning Electron Microscope (SEM) (see FIG. 8), and Fourier transform infrared (FT-IR) (see FIG. 9), among others, identified cationic ZIF-8 with defects⁺-I^-And (4) synthesizing.

As can be seen from FIG. 5, ZIF-8⁺-I^-(30:1)、ZIF-8⁺-I^-(20:1) is essentially consistent with the PXRD results for ZIF-8, which indicates that doping with the imidazolyl cationic ligand does not degrade the crystallinity of the material.

As can be seen from FIG. 6, "I" is present due to the product^-", it can be seen from the figure that the presence of iodine in the product was consistent with the prediction, thus indicating ZIF-8⁺-I^-(30:1) successful synthesis.

As can be seen from FIG. 7, ZIF-8 is⁺-I^-Dissolved in 60. mu.L of deuterated hydrochloric acid, and then 0.6mL of deuterated dimethylsulfoxide was added to test for NMR. It can be seen that doping with varying amounts of imidazolyl cationic ligands, there is a single peak of methyl at a displacement value of 3.68, which is the methylation of the "N" on 2-methylimidazole to form "N⁺-CH₃"group, from which it was seen that successful doping of the imidazolyl cationic organic ligand into the backbone of ZIF-8 results in the product ZIF-8⁺-I^-And the nuclear magnetic peak increases with the increase of the doping amount.

As can be seen from FIG. 8, two ZIF-8 types⁺-I^-(30:1)、ZIF-8⁺-I^-(20:1) the morphology and size of the ZIF-8 was substantially unchanged from those of pure ZIF-8, and thus ZIF-8⁺-I^-The morphology of ZIF-8 can be basically maintained.

FIG. 9 is ZIF-8⁺-I^-(30:1) Infrared Spectrum and data: 2926(w),1570(w),1458(w),1422(w),1310(m),1178(m),1146(s),993(m),953(w),847(w),758(s),692(m) cm^-1。

FIG. 10 is a thermogravimetric plot showing that ZIF-8 begins to lose weight at 500 ℃ and ZIF-8⁺-I^-Weight loss started at 150 ℃ and stopped at 80%, presumably due to ligand doping of the imidazolyl cation into the backbone, resulting in ZIF-8⁺-I^-Unstable structureAnd then weight loss started again until 500 ℃, which is consistent with ZIF-8.

FIG. 11 shows three material pairs N₂As can be seen from the adsorption/desorption curves of (A), ZIF-8 is compared with the original ZIF-8⁺-I^-The Brunauer-Emmett-Teller (BET) specific surface area and pore volume of the samples gradually decreased with increasing doping of the imidazolyl cationic ligand. ZIF-8, although doping of imidazolyl cationic ligands resulted in a decrease in these properties⁺-I^-The sample has sufficient cavities and large surface area to adsorb I₂The molecules (see table 2) were used,

TABLE 2 ZIF-8⁺-I^-(30:1)、ZIF-8⁺-I^-(20:1) specific surface area and pore size of ZIF-8

Absorbents	S_BET(m²·g^-1)	V_pore(cm³·g^-1)
			ZIF-8	1637	2.79
ZIF-8⁺-I^-(30:1)	1388	2.13
			ZIF-8⁺-I^-(20:1)	1270	1.83

Examples of Performance test

Test example 1

1)ZIF-8、ZIF-8⁺-I^-(30:1), and ZIF-8⁺-I^-(20:1) para-I in n-hexane₂Adsorption experiment of (1).

Respectively weighing ZIF-8 and ZIF-8⁺-I^-(30:1), and ZIF-8⁺-I^-(20:1) 10mg of each of the three materials, preparing 3000mg/L iodine n-hexane solution, adding 10mL of the solution into 3 sample bottles, adding the three materials into the solution, and standing. Taking out 0.5mL of supernatant at intervals of 0h, 2h, 6h, 9h, 12h, 24h and 48h, diluting to 5mL by using n-hexane, measuring the ultraviolet absorption of the solution between 400nm and 600nm by using an ultraviolet spectrophotometer, drawing a curve and calculating the adsorption amount of iodine. The results of the experiment are shown in FIG. 13.

In FIG. 12, FIGS. 12-A, 12-B and 12-C are ZIF-8, respectively⁺-I^-(30:1) and ZIF-8⁺-I^-(20:1) UV absorption of the supernatant in iodine-containing n-hexane at various times, and observation revealed that ZIF-8 was comparable to ZIF-8⁺-I^-The UV absorbance of the supernatant decreased rapidly with time, which means ZIF-8⁺-I^-The material has high-efficiency adsorption effect on iodine in n-hexane. The 12-D diagram is obtained through calculation, and ZIF-8 is seen from the data⁺-I^-(20:1) the adsorption of iodine in n-hexane of the material was as high as 2200mg/g, which is about 1000mg/g higher than the adsorption of iodine in n-hexane of ZIF-8, and thus ZIF-8⁺-I^-Showing a high-efficiency iodine adsorption function.

Test example 2

1)ZIF-8、ZIF-8⁺-I^-(30:1), and ZIF-8⁺-I^-(20:1) in the pair I₂Adsorption experiments of the vapors.

Respectively weighing ZIF-8 and ZIF-8⁺-I^-(30:1), and ZIF-8⁺-I^-(20:1) putting 10mg of the three materials into a sample, weighing a large amount of iodine elementary substance, adding the iodine elementary substance into a sample bottle,they were simultaneously placed in jars covered with lids and the jars were placed in a constant temperature oven at 75 ℃. Sample bottles filled with the materials are weighed at intervals of 0h, 1h, 3h, 6h, 9h, 12h, 24h, 36h and 48h respectively, and finally the iodine vapor adsorption quantity is calculated. The results of the experiment are shown in FIG. 14.

As can be seen from FIG. 13, ZIF-8⁺-I^-Compared with ZIF-8, the adsorption of iodine vapor is slightly increased, and the adsorption increasing effect of the ZIF-8 on iodine vapor is not obvious from the adsorption increasing effect of iodine in normal hexane, which is probably caused by different mechanisms of two adsorption processes of solution and steam.

Test example 3

To study ZIF-8⁺-I^-The cytotoxicity test was carried out, and two cell lines, melanoma cells (B16F10) and glioma cells (U87), were selected as the study subjects. 5.18mg of pure ZIF-8 and 5.21mg of ZIF-8 were weighed out separately⁺-I^-(30:1), completely dispersing the two materials in 5mL of deionized water, and adding corresponding PBS dry powder (12.4 mg. mL) into 4mL of the prepared solution^-1) Ultrasonic dissolving and paving: 150 μ L per well, 4 replicates. The most concentrated group is directly diluted by 2 times (serum-free DMEM), ZIF-8 and ZIF-8 by using the stock solution after being directly used by PBS buffer solution⁺-I^-The concentration of the mixture was 62.5. mu.g/mL, 125. mu.g/mL, 250. mu.g/mL, and 500. mu.g/mL in this order, and the mixture was incubated for 24 hours, MTT 100. mu.L was added, and after 4 hours, the plate was turned over, and dimethyl sulfoxide 100. mu.L was added. Shaking on a shaker for 3min, and testing the absorbance at 570nm with a microplate reader to obtain the corresponding survival rate.

The experimental results are as follows: as can be seen from FIG. 14, the activity of tumor cells was hardly decreased with the increase of the concentration of pure ZIF-8 in the B16F10 cell line, so that pure ZIF-8 was not significantly toxic to B16F10 cells, but with the increase of ZIF-8⁺-I^-The activity of the tumor cells is reduced in a step manner by increasing the concentration. It is noted that when ZIF-8 is used⁺-I^-When the concentration of (2) is 500. mu.g/mL, the activity of tumor cells is reduced to 40% or less, so that ZIF-8⁺-I^-Has obvious toxicity to B16F10 cells. The tumor cell viability was slightly reduced with increasing concentrations of pure ZIF-8 in the U87 cell line, indicating that ZIF-8 was weakly present in the U87 cell lineToxicity. But with ZIF-8⁺-I^-The activity of tumor cells decreases rapidly with increasing concentration. It is noted that U87 tumor cells were completely killed (cell viability around 20% was considered to be completely killed) at a concentration of 500. mu.g/mL, thus ZIF-8⁺-I^-Has great toxicity to U87 cells, and the experimental results show that ZIF-8 is⁺-I^-Has obvious anticancer effect and is an anticancer material with great potential.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.

Claims

1. A preparation method of a cation-deficient ZIF porous material is characterized by comprising the following steps:

(1): in an organic solvent, mixing and reacting an imidazole compound with methyl iodide to obtain an imidazole-based cationic ligand;

(2): and (2) dissolving the imidazole-based cationic ligand obtained in the step (1) and an imidazole-based compound in water, adding metal salt, uniformly mixing, and standing for reaction to obtain the cation-deficient ZIF porous material.

2. The method according to claim 1, wherein in the step (1), the organic solvent is one or more selected from tetrahydrofuran, dimethylformamide, dioxane, acetone, dimethylsulfoxide, methanol, ethanol, acetonitrile, benzene and toluene.

3. The preparation method according to claim 1, wherein in the step (1) and the step (2), the imidazole compound is one or more selected from imidazole, 2-methylimidazole, benzimidazole, imidazole-2-carbaldehyde, 2-chloro-imidazole and 2-phenylimidazole.

4. The preparation method according to claim 1, wherein in the step (1), the molar ratio of the methyl iodide to the imidazole compound is 1:1-3: 1.

5. The method according to claim 1, wherein in the step (1), the reaction time is 8 to 24 hours and the reaction temperature is 55 to 75 ℃.

6. The preparation method according to claim 1, wherein in the step (2), the molar ratio of the imidazolyl cationic ligand to the imidazole compound is 1:30 to 1: 20.

7. The preparation method according to claim 1, wherein in the step (2), the metal salt is one or more of zinc acetate, zinc nitrate, cobalt acetate and cobalt nitrate.

8. The preparation method according to claim 1, wherein in the step (2), the molar ratio of the metal salt to the imidazole compound is 1:40 to 1: 70.

9. A cation-deficient ZIF-based porous material obtained by the production method according to any one of claims 1 to 8.

10. Use of the cation deficient ZIF based porous material as claimed in claim 9 for iodine adsorption.