CN111732736B - A kind of Ni(II)-Salen ligand metal organic framework crystal material and its preparation method and application - Google Patents

Abstract

Ni(II)-Salen ligand metal organic framework crystal material and preparation method and application thereof. The chemical formula of the material is: {[Zn ₄ O(L) ₆ ]·DMF·H ₂ O} _n , where L is (R,R)-N,N'-bis(3-methyl-5-carboxysalicylidene base)-1,2-diphenylethylenediamine nickel (II) dicarboxylate dianion, n is the degree of polymerization. The metal-organic framework crystal material adopts a solvothermal synthesis method, and has the advantages of simple operation, low cost, high yield and easy large-scale industrial production. The prepared metal-organic framework crystal material has high thermal stability (400°C), and the BET specific surface area is 228 m ² /g. The adsorption capacity of CO ₂ at 273 K and 1 atm was 18.8 m ³ /g. In the presence of an oxidant, the selective oxidation of styrene in the aqueous phase is catalyzed to form benzaldehyde with a yield of 99%, and the catalyst is recycled five times with little loss of activity. In the presence of tetrabutylammonium bromide, 1 atm, 50 °C solvent-free catalyzed the reaction of epoxy styrene and _CO to produce styrene carbonate with a yield of 91%, and the catalyst was recycled five times and still maintained its activity. This material is a good heterogeneous catalyst.

Description

A kind of Ni(II)-Salen ligand metal organic framework crystal material and its preparation method and application

technical field

The invention belongs to the field of preparation and application of MOFs new materials, in particular to (R,R)-N,N'-bis(3-methyl-5-carboxysalicylidene)-1,2-diphenylethyl Preparation method of metal-organic framework with nickel (II) diamine as ligand and application in the field of gas adsorption and catalysis.

Background technique

Metal-organic frameworks (MOFs) represent a class of hybrid organic-inorganic ordered network supramolecular materials, which are ordered network structures composed of organic bridging ligands and inorganic metal ions. Three-dimensional layered and three-dimensional network structure. These materials consist of rigid multi-tooth bridging struts and metal nodes. High micropore volume, large pore size, and high metal content that may provide active sites are important features of this class of materials.

MOFs based on metal-Salen complexes are usually prepared by a direct method, that is, directly using metal complexes as linkers and metal nodes to self-assemble in situ to construct MOFs. As mentioned above, metal-salen complexes are a class of homogeneous catalysts with excellent performance but are prone to pollution and waste, and are difficult to recycle. Therefore, its further application in the field of catalysis is limited. It is an effective method to obtain heterogeneous catalysts by loading on mesoporous composites, and it is an excellent method to build metal-organic frameworks based on them. MOFs are highly porous, ultra-high specific surface area, The stable physical/chemical properties are an ideal immobilization material, and the immobilization sites provided by MOFs are much higher than other common materials, the immobilization capacity is stronger, and it is not easy to be detached after multiple cycles after immobilization; The introduction of specific active groups into the framework can enhance the reaction ability and realize the tandem catalysis of multi-step reactions; in addition, the ligands can be modified to construct MOFs with specific structures to achieve synergistic catalysis. In conclusion, the rich geometry, diversity of catalytic centers, and modifiability of MOFs endow the catalyst with more catalytic forms.

The heterogeneous catalyst synthesized by the immobilization strategy of preparing MOFs not only perfectly overcomes the problems of difficult recovery and instability caused by homogeneous catalysts, but also has more catalytic forms and framework structures, and has a wider range of applications. Based on metal Salen MOFs prepared by complexes have gradually attracted the attention of researchers, and related research has become more and more in-depth. The construction of MOFs requires additional coordination sites of metal-Salen complexes to coordinate self-assembly with metal ions or metal clusters. The current reports mainly focus on carboxylic acid-type or pyridine-type metal-Salen ligands. As catalysts, such MOFs can be used to catalyze various types of reactions, such as: asymmetric siliconitrile, photodegradation, and Diels–Alder reactions, etc. (Hu YH, Liu CX, Wang JC, et al. Inorganic Chemistry, 2019, 58 ( 8): 4722-4730; Li QZ, Zhang TF, Zhang ZK, et al. Inorganic Chemistry Communications, 2019, 99: 113-118; Lou LL, Yu K, Ding F, et al. Journal of Catalysis, 2007, 249 (1 ): 102-110; Huang J, Fu X, Wang G, et al. Dalton Transactions, 2012, 41(35): 10661-10669). For example, Jian-Fang Ma's research group (Li J, Yang J, LiuY, et al.Chemistry, 2015, 21(11):4413-4421) in 2015 used Fe-Salen complexes (III as organic ligands to combine with Two chiral MOFs (CMOF 1 and CMOF 2) were obtained by in situ self-assembly of transition metals Zn ²⁺ and Cd ²⁺ . It was found that the prepared crystalline materials could catalyze the degradation of 2-chlorophenol under visible light conditions. Compared with the control homogeneous catalyst Fe-Salen complex (III), CMOF 1 and CMOF 2 show higher catalytic activity, which is speculated not only to benefit from the highly porous properties of MOFs, but also to increase the interaction between the catalyst and the degraded species. It also benefits from the OH radicals generated by visible light irradiation. Under acidic conditions, the active metal center first combines with hydroxyl groups, and then reacts with hydrogen peroxide to obtain [salen-Fe ^III OOH], which is then exposed to visible light to obtain [salen-Fe III OOH]. Fe(V)=O] and OH radicals, OH radicals are significantly more reactive than [salen-Fe(V)=O]. The generated OH radicals immediately react with the degraded species, thereby accelerating the reaction process and improve the catalytic efficiency.

Ying-Ying Liu's research group (Wang HH, Yang J, Liu YY, et al. Crystal Growth & Design, 2015, 15(10): 4986-4992) used the precursor of Salen complex to interact with barium chloride and sodium chloride in situ Self-assembled sites to obtain a porous trimetal organic framework, Fe ³⁺ chelates with N,N,O,O tetradentate to form metal centers, and the carboxyl groups of Salen ligands coordinate with Ba ²⁺ and Na ⁺ atoms to generate three-dimensional periodicity network, resulting in a periodic network crystalline supramolecular catalyst, which is also the first ternary metal MOFs containing Fe ^III based on Schiff base ligands and successfully applied to catalyze the catalysis of 2-CP, 3-CP and 4-CP. Photodegradation, the study found that the photocatalytic degradation activity of 4-CP is higher than that of 2-CP and 3-CP, which is generally considered to be caused by the action of phenolic hydroxyl group. The electron density of the carbon atoms in the position and the ortho position, so these two positions are vulnerable to attack by electrophiles, while the para position is weaker and less active for degradation.

As organic ligands, dicarboxylic acid compounds have the characteristics of strong coordination ability, multiple coordination modes, and easy formation of hydrogen bonds. (R,R)-N,N'-bis(3-methyl-5-carboxysalicylidene)-1,2-diphenylethylenediamine nickel (II) has two carboxyl coordination sites, and Metal ions or metal clusters can form a variety of coordination modes, and can obtain MOFs with diverse structures. In addition, (R,R)-N,N'-bis(3-methyl-5-carboxysalicylidene)-1,2-diphenylethylenediamine nickel (II) is coordinated with divalent nickel ions , which can be used as active centers to catalyze many organic reactions.

According to the literature, (R,R)-N,N'-bis(3-methyl-5-carboxysalicylidene)-1,2-diphenylethylenediamine nickel (II) is a new type of metal Salen ligands, which coordinate with metal ions to form metal-organic frameworks have not been reported in literature.

SUMMARY OF THE INVENTION

The first technical problem to be solved by the present invention is to provide a microporous metal organic framework crystal material with stable structure and high specific surface area.

The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned metal organic framework crystal material, which is simple and easy to implement, low in cost, high in yield, and easy for large-scale industrial production.

The third object of the present invention is to provide the application of the above-mentioned metal organic framework crystal material in the field of gas adsorption and catalysis.

The present invention utilizes (R,R)-N,N'-bis(3-methyl-5-carboxysalicylidene)-1,2-diphenylethylenediamine nickel (II) to have strong coordination It is the first time that the above-mentioned ligands coordinate with Zn ²⁺ to form a novel metal-organic framework crystal material. Such materials usually have pores and large specific surface area, and have good application prospects in the fields of catalysis and gas adsorption.

In order to achieve the above object, the present invention adopts the following technical solutions:

A Ni(II)-Salen ligand metal organic framework crystal material according to the present invention has the following chemical formula {[Zn ₄ O(L) ₆ ]·DMF·H ₂ O} _n , wherein L is (R, R)-N,N'-bis(3-methyl-5-carboxysalicylidene)-1,2-diphenylethylenediamine nickel (II) dicarboxylate dianion, n is the degree of polymerization .

The crystal of the metal organic framework described in the present invention belongs to the monoclinic system, and the space group is I2.

A kind of Ni(II)-Salen ligand metal organic framework crystal material of the present invention and its preparation method and application, comprise the following steps:

(1) Divalent zinc salt compound, (R,R)-N,N'-bis(3-methyl-5-carboxysalicylidene)-1,2-diphenylethylenediamine nickel (II) Dissolve in solvent, stir well, then add to threaded transparent high temperature glass vial.

(2) heating and heating, the reactant reacts at a certain temperature for a period of time, gradually lowering the temperature, cooling to room temperature, filtering, washing with DMF or DMA, and drying to obtain a metal organic framework crystal material.

The zinc salt compound of the present invention is a zinc nitrate salt, a zinc chloride salt, a zinc sulfate salt, a zinc acetate salt and a zinc perchlorate salt; the zinc ion is +2 valence;

The nickel ion of the present invention is +2 valence;

Solvent DMF or DMA of the present invention;

The zinc salt compound of the present invention is combined with (R,R)-N,N'-bis(3-methyl-5-carboxysalicylidene)-1,2-diphenylethylenediamine nickel (II) The molar ratio of zinc salt compound is 2:0.8～2:1, and the molar ratio of zinc salt compound and solvent is 1:1000～1:5000;

The reaction temperature of the present invention is 80 ℃～100 ℃;

The reaction time of the present invention is 1 to 120 hours;

The heating rate of the present invention is 1°C/h to 5°C/h.

The cooling rate of the present invention is 1°C/h to 10°C/h.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The structure of the metal organic framework crystal material synthesized by the present invention is novel and unique.

(2) The present invention adopts (R,R)-N,N'-bis(3-methyl-5-carboxysalicylidene)-1,2-diphenylethylenediamine nickel (II) and Zn ² The ⁺ salt is used as the raw material, and the solvothermal synthesis method is adopted, which is simple and feasible, low in cost, high in yield, and easy for large-scale industrial production.

(3) The metal organic framework crystal material of the present invention has the characteristics of three-dimensional network structure and porosity, specific surface area (BET specific surface area is 228m ² /g), stable (thermal stability up to 400 ° C), 273K, CO ₂ under 1atm The adsorption amount was 18.8 cm ³ /g. In the presence of an oxidant, the selective oxidation of styrene in the aqueous phase to form benzaldehyde is achieved with a yield of 99%, and the catalyst is recycled five times with almost no loss of activity. In addition, in the presence of tetrabutylammonium bromide, the reaction of epoxy styrene and _CO2 was catalyzed under solvent-free reaction conditions at 1 atm and 50 °C to produce styrene carbonate with a yield of 91%. The catalyst was recycled five times and its activity still remain. It shows that the material has good application prospects in the fields of gas adsorption and catalysis.

Description of drawings

Fig. 1 Molecular structure of Ni(II)-Salen(L) ligand of metal organic framework crystal material of the present invention. FIG. 2 is the coordination mode of the metal-organic framework crystal material Ni(II)-Salen(L) of the present invention.

Fig. 3 is a secondary structural unit diagram of the metal organic framework crystal material of the present invention.

FIG. 4 is a diagram of the coordination cubic unit of the metal organic framework crystal material of the present invention.

Fig. 5 is a structural diagram of the double interpenetrating topos of the metal organic framework crystal material of the present invention.

FIG. 6 is an infrared spectrogram of the metal organic framework crystal material of the present invention.

Fig. 7 is a thermogravimetric analysis diagram of the metal organic framework crystal material of the present invention.

FIG. ₈ is an N adsorption-desorption isotherm diagram of the metal organic framework crystal material of the present invention at 77K. Fig. 9 The adsorption diagram of _CO2 at 273K for the metal-organic framework crystal material of the present invention.

Fig. 10 ¹ H NMR chart of the metal organic framework crystal material of the present invention catalyzing the oxidation of styrene to benzaldehyde.

Fig. 11 ¹³ C NMR chart of the metal organic framework crystal material of the present invention catalyzing the oxidation of styrene to benzaldehyde.

Fig. 12 ¹ HNMR chart of the metal organic framework crystal material of the present invention catalyzing epoxy styrene and CO ₂ to generate styrene carbonate.

Fig. 13 ¹³ CNMR chart of the metal organic framework crystal material of the present invention catalyzing epoxy styrene and CO ₂ to generate styrene carbonate.

Detailed ways

The Ni(II)-Salen ligand metal organic framework crystal material of the present invention and its preparation method and application, the synthesis steps and structure are characterized as:

The divalent zinc salt compound, (R,R)-N,N'-bis(3-methyl-5-carboxysalicylidene)-1,2-diphenylethylenediamine nickel(II) was dissolved in In the solvent, stir evenly, then add it into a threaded high temperature resistant glass vial, heat up slowly, after the reactant reacts at a certain temperature for a period, gradually reduce the temperature, cool to room temperature, filter, wash with solvent, and dry to obtain {[ Zn ₄ O(L) ₆ ]·DMF·H ₂ O} _n crystal material. Then the single crystal structure of the compound was measured by Rigaku RAXIS~RAPID IP X-ray diffractometer, the infrared spectrum of the compound was measured by Nicolet Nexus 470FTIR infrared spectrometer, and the thermogravimetric/differential thermal analysis of the sample was tested on Q600 SDT thermogravimetric X-ray diffraction was tested on Bruker D8 X-ray diffractometer, C, H, N elemental analysis was tested on German Vario EL III elemental analyzer, nitrogen adsorption isotherm was tested on Quantachrome AS-1MP instrument, ¹ H NMR and ¹³ C NMR was tested on an Agilent DD2-400 nuclear magnetic resonance apparatus in the United States.

Specific examples are as follows:

Synthesis and Characterization of {[Zn ₄ O(L) ₆ ]·DMF·H ₂ O} _n

The Ni(II)-Salen(L) ligand (10mg, 0.0169mmol, 1.0equiv) was placed in a 10mL threaded transparent high temperature glass vial, followed by zinc nitrate hexahydrate (10mg, 0.0338mmol, 2.0equiv), 2mL DMF, ultrasonically treated for 2 minutes to dissolve, after complete dissolution, tighten the bottle cap, place it in an automatic program-controlled heating box, raise the temperature at a rate of 5°C/h to 80°C, keep warm for 3 days, and then heat at 5°C/h. h cooling rate was reduced to room temperature, filtered to obtain blocky brick red crystals, washed with DMF, and air-dried at room temperature to obtain 8.0 mg with a yield of 80% (calculated by Ni-Salen). The theoretical value (%) of elemental analysis calculated according to C ₁₉₈ H ₁₆₂ N ₁₄ Ni ₆ O ₄₂ Zn ₈ is: C, 55.49; N, 4.58; H, 3.81; experimental value: C, 55.38; N, 4.64; H, 3.86 . IR(4000-400cm ^-1 ): 3435(vs), 3059(w), 1660(vs), 1610(vs), 1400(vs), 1323(m), 1249(w), 754(w), 700 (w).

90kV和50mA的工作电压和电流，以ω扫描方式收集进行Lp因子校正，吸收校正使用CrystalClear程序(Müller P.,Herbst-Irmer R.,Spek A.L.,et al.InternationalUnion of Crystallography Book Series,Oxford University Press:New York,2006,Chapter 7)。用直接法解析结构，然后用差值傅里叶法求出全部非氢原子坐标，有机氢原子采用理论加氢法得到，用最小二乘法对结构进行修正。计算工作在微机上用SHELXTL程序包完成(Sheldrick,G.M.:Crystal structure refnement with SHELXL.ActaCrystallogr.2015,C71:3–8.)，所的化合物结构为{[Zn₄O(L)₆]·DMF·H₂O}_n。表1为该金属有机框架材料的主要晶体学数据。The single crystal X-ray diffraction data of the obtained compound was measured on a Rigaku RAXIS~RAPID IP X-ray diffractometer, and the single crystal X-ray diffraction data was collected at room temperature. The diffractometer uses CuKα rays with a wavelength of

The operating voltage and current of 90kV and 50mA were collected in ω scan mode for Lp factor correction, and the absorption correction was performed using the CrystalClear program (Müller P., Herbst-Irmer R., Spek AL, et al. International Union of Crystallography Book Series, Oxford University Press : New York, 2006, Chapter 7). The structure is analyzed by the direct method, and then the coordinates of all non-hydrogen atoms are obtained by the difference Fourier method. The organic hydrogen atoms are obtained by the theoretical hydrogenation method, and the structure is corrected by the least square method. The calculation work was done on the microcomputer with the SHELXTL package (Sheldrick, GM: Crystal structure refnement with SHELXL. ActaCrystallogr. 2015, C71: 3–8.), the compound structure is {[Zn ₄ O(L) ₆ ]·DMF · H ₂ O} _n . Table 1 is the main crystallographic data of the metal organic framework material.

Table 1

R ₁ =Σ||Fo|-|Fc||/Σ|Fo|.wR ₂ =[Σw(Fo ² -Fc ² ) ² /Σw(Fo ² ) ² ] ^1/2

符号是(4¹².6³)(图5)。Figure 1 is a molecular structure diagram of the ligand Ni(II)-Salen(L). X-ray single crystal diffraction studies show that the compound is monoclinic with space group I2. The crystallographic data and structural refinement parameters are shown in Table 1. Each asymmetric unit contains 6 Ni(II)-Salen ligands, 4 Zn(II) atoms, 1 coordinated water molecule and one coordinated DMF molecule. Each Zn atom is coordinated with 3 carboxyl groups, which are derived from 3 different ligands. The secondary structural unit is a tetranuclear Zn-O octahedral structure [Zn ₄ O(CO ₂ ) ₆ ] ( FIG. 3 ). Since one Zn atom coordinates a water molecule and a DMF molecule, the Zn atom is 6-coordinated, and the other three Zn atoms are 4-coordinated, resulting in some deformation of the octahedral structure. Six ligands are attached to each secondary building block, and the two carboxyl groups of each Ni(II)-Salen ligand are in (κ ¹ -κ ¹ -μ ₂ ) mode with two Zn atoms of the secondary building unit. bit (Figure 1). The topological structure analysis of the compound confirms that the linear Ni(II)-Salen maintains its two-connectivity, and each secondary structural unit acts as a six-connected node, and the Ni(II)-Salen ligand is connected to the secondary structural unit end-to-end to form pcu lattice (Figure 4). Ni(II)-Salen connects with secondary structural units to form a doubly interpenetrating 3D network, topology of the network

The symbol is (4 ¹² .6 ³ ) (Figure 5).

Figure 6 shows the infrared spectrum of the metal-organic framework, which was tested on a Nicolet Nexus 470FTIR infrared spectrometer using spectrally pure potassium bromide pellets. Before the test, the sample and potassium bromide were dried under a UV lamp to remove the surface Water, measuring range 4000-400cm ^-1 . It can be seen from the infrared spectrum that 3300-3600 cm ^-1 is the stretching vibration absorption peak of the OH bond of water. Due to the coordination of ligands and metals, the absorption peaks of some groups were changed. 3059cm ^-1 is the υC-H vibration of the aromatic ring; 1660 is the C=N stretching vibration; 1610cm ^-1 and 1400cm ^-1 are the υ _s C=O and υ _as C=O vibration of the carboxyl group, respectively, and the absorption peak at 1323cm ^-1 is Skeletal vibration of υ(C=C) in the aromatic ring of the ligand.

Figure 7 shows the thermogravimetric/differential thermal analysis of the metal-organic framework was tested on a Q600 SDT thermogravimetric analyzer. After zero adjustment, 5-10 mg of the sample was weighed and placed in a ceramic dry pot for measurement. The measurement was carried out under a nitrogen atmosphere. The heating rate was set at 10°C/min, and the temperature was raised to 800°C. There are two distinct stages of weight loss, 17.6% weight loss between 30-400 °C, corresponding to the loss of 1 coordinated water molecule and 1 coordinated DMF molecule, as well as disordered solvent molecules in the pores; at 400-440 °C In between, there is a sharp weight loss of 22.4%, the organic ligands begin to decompose and the framework begins to collapse. The weight loss ended at 700°C for a total of about 51.7% weight loss.

Figure 8 shows the nitrogen adsorption isotherm of the metal-organic framework, which was measured on a Quantachrome AS-1MP instrument. Before the test, the sample was vacuum activated at 200 °C for 24 h to remove guest molecules in the sample pores. Using high-purity N ₂ (99.999%) at 77K in the pressure range of 10 ^-6 -1 to measure the amount of N ₂ adsorption and calculate the BET specific surface area. The physical adsorption-desorption isotherm is a typical microporous adsorption isotherm (type I), and its BET specific surface area is calculated to be 228 m ² /g.

Figure 9 shows the amount of CO ₂ adsorption of the metal-organic framework at 0.1-1 atm and 273 K, which was measured on a Quantachrome AS-1MP instrument. Before the test, the sample was vacuum activated at 200 °C for 24 h to remove the guest molecules in the sample pores. High purity _CO2 (99.998%) was used. As a result of the experiment, the adsorption amount of CO ₂ was 18.8 m ³ /g.

Steps for catalyzing the selective oxidation of styrene and hydrogen peroxide: styrene (2 mmol), 2 mL of water, hydrogen peroxide (3 mmol) and {[Zn ₄ O (L ) ₆ ]·DMF·H ₂ O} _n (0.025mol%), react at 60°C for 15 hours, add 1.5 mL of ethyl acetate after the reaction, centrifuge the reaction solution and the catalyst, extract and separate in this way 4 times, and combine the supernatants , concentrated, separated and purified by silica gel column chromatography to obtain benzaldehyde (eluent is petroleum ether: ethyl acetate = 25:1), passed through Agilent DD2-400 nuclear magnetic resonance instrument, CDCl ₃ as solvent, TMS as internal standard, The target product structure was characterized (Figure 10 and Figure 11).

Cyclic catalysis experiment: after each catalytic reaction, centrifuge to separate the catalyst, filter, wash the catalyst with dichloromethane and acetone in turn, and activate it by vacuum heating at 150°C for 24h, as the catalyst for the next cycle of catalysis. The product yields of 5 cycles of catalysis were 99%, 97%, 95%, 94%, and 92%.

Steps for catalyzing the ring expansion reaction of epoxystyrene with _CO : Epoxystyrene (10 mmol), tetrabutylammonium bromide (0.025 mmol) and {[ _Zn4 O(L) ₆ ]·DMF·H ₂ O} _n (0.05mol%), and a balloon with CO ₂ was placed on the top of the condenser tube, and the gas was replaced three times, and then the reaction was performed at 50°C for 12 hours, and the reaction was over. Then, 1.5 mL of ethyl acetate was added to the reaction system, and the reaction solution and the catalyst were centrifuged to separate the reaction solution and the catalyst. The extraction and separation were performed 4 times. The supernatants were combined, concentrated, and separated and purified by silica gel column chromatography to obtain the product. The product was purified by column chromatography (eluting The solvent was petroleum ether:ethyl acetate=12:1), and the structure of the target product was characterized by an Agilent DD2-400 nuclear magnetic resonance instrument, CDCl ₃ was the solvent, and TMS was the internal standard (Figure 12 and Figure 13).

Cyclic catalysis experiment: reaction with styrene oxide as the substrate, after each catalysis reaction, centrifuge to separate the catalyst, filter, wash with dichloromethane and acetone in turn, and activate under vacuum heating at 150 ° C for 24 hours, as the next time Catalysts in cycle catalysis. The product yields of 5 cycles of catalysis were 91%, 90%, 88%, 88%, and 85%.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any form. Any simple modifications made to the above embodiments according to the technical essence of the present invention without departing from the technical solution content of the present invention, Equivalent changes and modifications still fall within the scope of the technical solutions of the present invention.

Claims (10)

1. A kind of Ni (C)

)-The preparation method of the Salen ligand metal organic framework crystal material is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: a divalent zinc salt compound, (b) aR, R)-N,N' -bis (3-methyl-5-carboxysalicylidene) -1, 2-diphenylethylenediamine nickel (II) ((III))

) Dissolving in a solvent, stirring uniformly, and then adding into a transparent high-temperature-resistant glass vial with threads;

step two: slowly heating to 80-100 ℃ at a heating rate of 1-5 ℃/h, reacting for 1-120 hours, gradually reducing the temperature, cooling to room temperature at a cooling rate of 1-10 ℃/h, filtering, washing with a solvent, and drying to obtain a metal organic framework crystal material; the chemical formula is as follows:

{[Zn₄O(L)₆]·DMF·H₂O}_nwherein L is: (R, R)-N,N' -bis (3-methyl-5-carboxysalicylidene) -1, 2-diphenylethylenediamine nickel (II) ((III))

) Abbreviation of dicarboxylate dianion of (a);

wherein the chemical structural formula of L is as follows:

in the above chemical formula:

and n is the degree of polymerization.

2. Ni (according to claim 1)

) -a method for preparing a Salen ligand metal organic framework crystalline material, characterized in that: the crystal of the metal organic framework belongs to a monoclinic system, and the space group isI2。

3. Ni (according to claim 1)

) -a method for preparing a Salen ligand metal organic framework crystalline material, characterized in that: the zinc salt compound and (A) and (B)R, R)-N,N' -bis (3-methyl-5-carboxysalicylidene) -1, 2-diphenylethylenediamine nickel (N- (ll-butyl-N-ethyl-p-phenylenediamine)

) The molar ratio of the zinc salt compound to the solvent is 2: 0.8-2: 1, and the molar ratio of the zinc salt compound to the solvent is 1: 1000-1: 5000.

4. Ni (according to claim 1)

) -a method for preparing a Salen ligand metal organic framework crystalline material, characterized in that: the zinc salt compound is one of zinc nitrate salt, zinc chloride salt, zinc sulfate salt, zinc acetate salt and zinc perchlorate salt.

5. Ni (according to claim 1)

) -a method for preparing a Salen ligand metal organic framework crystalline material, characterized in that: the zinc ion in the zinc salt is +2 valence.

6. Ni (according to claim 1)

) -a method for preparing a Salen ligand metal organic framework crystalline material, characterized in that: and the solvent in the first step and the second step is one of DMF and DMA.

7. Root of herbaceous plantA Ni (Ni) (I) prepared according to claim 1

) -the use of a Salen ligand metal organic framework crystalline material, characterized in that: the metal organic framework crystal material catalyzes styrene to be oxidized in a water phase to generate benzaldehyde.

8. Ni (Ni) (according to claim 7)

) -the use of a Salen ligand metal organic framework crystalline material, characterized in that: the oxidant is one of hydrogen peroxide, tert-butyl alcohol peroxide, iodobenzene oxide, peracetic acid, m-chloroperoxybenzoic acid and sodium hypochlorite.

9. A Ni (C) (prepared according to claim 1)

) -the use of a Salen ligand metal organic framework crystalline material, characterized in that: the metal organic framework crystal material catalyzes epoxystyrene and CO in the presence of tetrabutylammonium bromide₂The reaction produces styrene carbonate.

10. Ni (according to claim 9)

) -use of a Salen ligand metal organic framework crystalline material, characterized in that: the catalytic reaction conditions are 1atm and no solvent at 50 ℃.

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