阅读说明：本技术 一种混合价态铁掺杂沸石咪唑酯骨架纳米材料的制备方法 (Preparation method of mixed-valence iron-doped zeolite imidazole ester framework nano material ) 是由 刘惠玉 王伟伟 于志昊 张皓渊 卫奇星 于 2019-09-17 设计创作，主要内容包括：本发明涉及一种混合价态铁掺杂沸石咪唑酯骨架纳米材料的制备方法。通过将二价和三价铁盐与硝酸锌同时分散于甲醇溶剂中形成铁-锌前驱体溶液,将2-甲基咪唑甲醇溶液与前驱体溶液混合,并置于40～100℃油浴中,持续磁力搅拌反应后,对产物进行离心、洗涤、干燥处理。得到产量较高、颗粒尺寸大小均一可控的混合价态铁掺杂沸石咪唑酯骨架纳米材料。本发明方法可通过调节二价和三价铁盐的比例实现总铁掺杂量最高达50％,锌铁离子的转化率分别可高达78％和60％。该方法简单,经济节约,反应后的母液可重复利用。所得纳米材料在超声诱导下具有较高的活性氧产生效率,在环境污染物降解和肿瘤声动力治疗中的应用价值很大,且可用于制备高浓度单原子铁-碳基催化剂。(The invention relates to a preparation method of a mixed valence state iron-doped zeolite imidazolate framework nano material. Divalent and trivalent iron salts and zinc nitrate are simultaneously dispersed in a methanol solvent to form an iron-zinc precursor solution, the 2-methylimidazole methanol solution and the precursor solution are mixed and placed in an oil bath at 40-100 ℃, and after continuous magnetic stirring reaction, the product is subjected to centrifugation, washing and drying treatment. The mixed valence state iron-doped zeolite imidazole ester framework nano material with higher yield and uniform and controllable particle size is obtained. The method can realize the highest total iron doping amount of 50 percent by adjusting the proportion of the ferrous salt and the ferric salt, and the conversion rates of zinc and iron ions can respectively reach 78 percent and 60 percent. The method is simple, economical and economical, and the mother liquor after reaction can be recycled. The obtained nano material has higher active oxygen generation efficiency under ultrasonic induction, has great application value in environmental pollutant degradation and tumor sonodynamic therapy, and can be used for preparing a high-concentration monatomic iron-carbon-based catalyst.)

1. A preparation method of a mixed valence state iron-doped zeolite imidazole ester framework nano material is characterized by comprising the following steps:

s01: simultaneously dispersing bivalent and trivalent ferric salts and zinc nitrate in a methanol solvent to form an iron-zinc metal cation precursor solution, wherein the molar ratio of zinc ions to methanol is 1: 100-1: 1000; wherein the molar ratio of divalent to trivalent iron ions is 2:1 to 1: 2; the molar ratio of total iron ions to zinc ions is 1: 50-1: 20;

s02: preparing a 2-methylimidazole methanol solution, mixing the 2-methylimidazole methanol solution with the precursor solution, and performing magnetic stirring reaction for 16-36 hours in an oil bath at the temperature of 40-100 ℃ to obtain a product, wherein the molar ratio of 2-methylimidazole to methanol is 1: 20-1: 200, and the molar ratio of 2-methylimidazole to zinc ions is 1: 4-1: 6;

s03: and centrifuging, washing and vacuum drying the product to obtain the mixed valence iron-doped zeolite imidazole ester framework nano material.

2. The preparation method according to claim 1, wherein the particle size of the prepared mixed-valence iron-doped zeolite imidazolate framework nano-material is 50-250 nm.

3. The method according to claim 1, wherein the ferrous salt is ferrous sulfate, ferrous ammonium sulfate or ferrous chloride.

4. The method of claim 1, wherein the ferric salt is selected from the group consisting of ferric chloride, ferric nitrate, ferric ammonium sulfate, and ferric acetylacetonate, and wherein the molar ratio of divalent to trivalent ferric ions is 2:1, 1:1, and 1: 2.

5. The method according to claim 1, wherein the magnetic stirring speed is 200 to 400 rpm.

6. The method according to claim 1, further comprising S04: and (3) recycling the mother liquor obtained after centrifugation in the S03, and preparing the mixed valence iron-doped zeolite imidazole ester framework nano material by using the mother liquor as a reaction solvent in the same method as that of the S01-S03.

7. The preparation method of claim 1, wherein the obtained mixed valence iron-doped zeolite imidazolate framework nano-material is applied to the acoustic dynamic catalysis of pollutant degradation and the application as a tumor treatment drug.

8. The preparation method of claim 1, wherein the obtained mixed valence iron-doped zeolite imidazolate framework nano-material is used for preparing a monoatomic iron-carbon-based catalyst.

The technical field is as follows:

the invention belongs to the technical field of functional nano materials, and particularly relates to a preparation method of a mixed valence state iron-doped metal organic framework nano material.

Background art:

the metal organic framework Materials (MOFs) are porous materials with three-dimensional space network structures formed by coordination self-assembly of transition metal ions and organic ligands, and the formed porous materials show unique physicochemical properties (such as controllable size, large specific surface area, high chemical stability and the like) of the nano materials on a nanoscale. Particularly, the transition metal single-atom carbon-based nano material with higher catalytic activity can be prepared under the high-temperature pyrolysis condition by utilizing the space confinement effect of the metal organic framework, and has wide application value in the fields of energy, catalysis and biomedicine. For example, Zhang et al (Journal of the American Chemical Society,2017,139(40),14143-14149) prepared a bimetallic Zn-Fe zeolitic imidazole framework material (i.e., iron-doped ZIF-8) by one-pot method using coordinated self-assembly in the methanol phase and subjected to high temperature pyrolysis to prepare a monatomic iron-based catalyst with high catalytic activity. Besides, a bimetallic Co-Zn or Ni-Zn zeolite imidazole framework material is also adopted, and the monatomic cobalt or nickel-based catalyst prepared by the same method shows better catalytic activity. Therefore, different transition metal ions are selected for coordination or doping, and MOFs with different structures and functions can be obtained, so that the MOFs has a wider application prospect.

The transition metal iron ions have better coordination capacity, and the iron ions are used as coordination center atoms, so that more unsaturated coordination structures are provided to generate more abundant active sites when the metal organic framework material is formed, and the transition metal iron ions attract wide attention in the fields of environmental protection, chemical engineering, energy, life science and the like. At present, many methods for synthesizing iron-doped ZIFs have been reported. However, few reports have been made on achieving high yields of iron-doped ZIF-8 with high catalytic activity at low temperatures. At the earliest by Fe³⁺And carrying out four or six coordination with imidazole ligand to obtain the product. Later, researchers developed an all-solid-state one-step synthesis to prepare Fe-doped ZIF-8. In the method, 1, 10-phenanthroline iron perchlorate is used as an iron-based additive, zinc oxide and 2-methylimidazole are used as a zinc source and a ligand respectively, and the iron-based additive is prepared at a relatively high temperature (180 ℃). However, how to design and control the reaction conditions to achieve directional assemblyThe target compound coordinated or doped by transition metal ions in mixed valence state is a great challenge facing the preparation field of the current metal organic framework material.

Compared with the conventional bimetallic metal-organic framework material, the metal ion center with mixed valence has the advantages of high density of catalytic active sites, high dispersity and the like. In addition, studies show that the ferric ion doped metal organic framework material containing unsaturated coordinated mixed valence iron center can form iron vacancy under certain conditions, and when a monatomic catalyst is formed through high-temperature phase transition, the unsaturated coordinated iron metal center can be activated to be converted from high valence to low valence (ferrous iron), so that the catalytic activity of the catalyst can be improved. At present, many reports on the preparation method of the mixed valence bimetallic-based metal-organic framework material exist. Erik et al prepared mixed valence cobalt center zeolitic imidazole framework materials by pyrolysis of cobalt acetate and imidazole ligands in a heptane/n-hexanol/water mixed solvent under reverse microemulsion conditions (Chemistry A European journal,2016,22, 3676-. Jiao et al synthesized a mixed valence copper-centered metal-organic framework material based on pyridine ligands by a solvothermal method (CrystEngComm, 2016,18, 8683-8687). Recently, Pu et al prepared mixed valence iron-centered metal-organic frameworks based on phthalic acid using high temperature solvothermal (catalysis science & Technology, 2017,7, 1129-. Samia et al prepared a mixed valence state iron center metal-organic framework material based on a phenazine ligand by a closed reaction for two months (ACSApplied Materials & Interfaces,2017,9,26210-26218) using low temperature self-assembly. However, simple, economical and preparative methods based on mixed-valence iron-centered bimetallic zeolitic imidazolate framework materials with specific nitrogen-containing imidazolate ligands have been reported, and it is difficult to control the concentration of iron ions involved in coordination. Therefore, there remains a significant challenge to preparing mixed-valence metallic iron ion-doped ZIF-8 nanoparticles.

In view of the above discussion, the present invention discloses a method for preparing a mixed valence iron-doped zeolite imidazolate framework nanomaterial. The method can realize effective regulation of divalent and trivalent iron ions under the condition of low temperature, and the maximum iron doping amount of the prepared mixed valence iron-doped zeolite imidazole ester framework nano material reaches 50 percent. And the conversion rates of the metal zinc and iron ions are respectively as high as 78 percent and 60 percent. The method has the advantages of simple preparation process, economy, saving, mild conditions and reutilization of the mother liquor after reaction. The prepared nano particles are uniform and controllable in size and can be used for preparing a high-concentration monatomic iron-based catalyst; and has higher active oxygen generation efficiency under the drive of ultrasound, and has potential application value in the degradation of environmental pollutants and the application of cancer sonodynamic therapy.

The invention content is as follows:

aiming at the blank existing in the preparation of mixed-valence iron-zinc bimetallic zeolite imidazole ester framework nano-materials at low temperature, the invention aims to overcome the application defects of the conventional bimetallic zeolite imidazole ester framework materials, further improve the catalytic activity of MOFs and expand the new application thereof. Provides a method for realizing the controllable synthesis of mixed valence iron-zinc bimetallic zeolite imidazole ester framework materials by utilizing competitive adsorption and substitution among transition metal ions with different valences under the condition of low temperature.

In order to realize the purpose of the invention, the technical scheme of the invention is as follows:

a preparation method of a mixed valence state iron-doped zeolite imidazole ester framework nano material is characterized by comprising the following steps:

s01: simultaneously dispersing bivalent and trivalent ferric salts and zinc nitrate in a methanol solvent to form an iron-zinc metal cation precursor solution, wherein the molar ratio of zinc ions to methanol is 1: 100-1: 1000; wherein the molar ratio of divalent to trivalent iron ions is 2:1 to 1: 2; the molar ratio of total iron ions to zinc ions is 1: 50-1: 20;

s02: preparing a 2-methylimidazole methanol solution, mixing the 2-methylimidazole methanol solution with the precursor solution, and performing magnetic stirring reaction for 16-36 hours in an oil bath at the temperature of 40-100 ℃ to obtain a product, wherein the molar ratio of 2-methylimidazole to methanol is 1: 20-1: 200, and the molar ratio of 2-methylimidazole to zinc ions is 1: 4-1: 6;

s03: and centrifuging, washing and vacuum drying the product to obtain the mixed valence iron-doped zeolite imidazole ester framework nano material, which can also be called mixed valence iron-doped-ZIF-8 nano material for short.

Centrifuging the formed product and recycling the mother solution, wherein the prepared nano material has uniform and controllable particle size and can be used for preparing a high-concentration monatomic iron-based catalyst; and has higher active oxygen generation efficiency under the drive of ultrasound, and has potential application value in the degradation of environmental pollutants and the application of cancer sonodynamic therapy.

The ferrous salt is ferrous sulfate, ammonium ferrous sulfate or ferrous chloride. The ferric salt is ferric chloride, ferric nitrate, ammonium ferric sulfate or ferric acetylacetonate, wherein the molar ratio of the divalent iron to the trivalent iron is 2:1, 1:1 or 1: 2.

Further, the magnetic stirring speed is 200-400 r/min.

Further, the method is characterized by further comprising the step of S04: and (3) recycling the mother liquor obtained after centrifugation in the S03, and preparing the mixed valence doped-ZIF-8 nano material by using the mother liquor as a reaction solvent in the same method as that of the S01-S03.

Further, the method is characterized in that the obtained mixed valence state iron doped ZIF-8 nano material is applied to the acoustic dynamic catalysis of pollutant degradation and the application of the material as a tumor treatment drug.

Further, the method is characterized in that the obtained mixed valence state iron-doped ZIF-8 nano material is used for preparing the monatomic iron-carbon-based catalyst.

Preferably, the total molar ratio of iron ions to zinc ions is 1: 30.

Preferably, the combination of the divalent and trivalent iron salts is ferrous ammonium sulfate and ferric ammonium sulfate, and the molar ratio of the ferrous ammonium sulfate to the ferric ammonium sulfate is 1: 1.

Preferably, the molar ratio of the zinc ions to the methanol is 1: 100-1: 1000; the molar ratio of the 2-methylimidazole to the methanol is 1: 20-1: 200; the molar ratio of the zinc ions to the 2-methylimidazole is 1: 4-1: 6;

preferably, the reaction temperature is 60 ℃, the stirring speed is 300 r/min, and the reaction time is 24 hours.

The particle size of the prepared mixed valence iron doped ZIF-8 nano material is 50-250 nm.

The key point of the design of the invention is that in the process of forming ZIF-8, the competitive adsorption effect of the metal zinc-imidazole framework on divalent and trivalent iron ions is utilized, and the valence state balance between the two plays a key role in the adsorption and substitution of stable ions. Under the action of higher coordination ability of iron ions, the doping amount of the iron ions is effectively controlled, and the conversion rate of metal zinc ions and iron ions is improved.

Compared with the prior art, the invention has the following remarkable advantages:

the mixed valence state iron-doped metal organic framework nano material prepared by the invention has uniform and adjustable particle size, simple preparation method, mild conditions, economy and conservation; the process can be enlarged; few synthesis regulation parameters, low raw material cost and industrial production.

Description of the drawings:

FIG. 1 is a TEM photograph of a 50nm mixed valence iron-doped ZIF-8 nanomaterial prepared.

FIG. 2 XRD patterns of mixed-valence iron-doped ZIF-8 nanomaterial prepared in examples 2 and 3.

FIG. 3 example 1 sample capture experiment for singlet oxygen generation under ultrasound.

FIG. 4 in vitro cellular safety and sonodynamic therapeutic efficacy of the sample of example 6. (ns: P0.05;. P < 0.001;. P <0.0001)

Detailed Description

The present invention will be described in more detail with reference to the following examples and the accompanying drawings.

Capture experiment for generating active oxygen under ultrasonic action

Respectively preparing 1mg/mL DPA dimethyl sulfoxide solution and 50mL 100 mu g/mL mixed valence state iron-doped-ZIF-8 nano material PBS solution by using 9, 10-diphenylanthracene (9,10. diphenylanthracene; DPA) as a singlet oxygen capture agent; 3.2mL of the material solution was weighed out and mixed with 80. mu.L of DPA solution at 1.0MHz and 1.5W/cm²Under the ultrasonic condition, after ultrasonic treatment for different time, ultraviolet-visible absorption spectrum is used for measurementThe solution absorbs in the range of 300-450 nm, so that the capability of the material as a sound sensitive agent for generating active oxygen (singlet oxygen) under the action of ultrasound is evaluated.