Copper-based metal-organic framework material based on binaphthyl skeleton and its preparation method and application

Abstract

The present invention relates to the technical field of metal-organic framework materials and discloses a copper-based metal-organic framework material based on a binaphthyl skeleton, its preparation method, and application. The present invention uses divalent copper salts such as copper nitrate as raw materials, a pyridine-functionalized binaphthyl compound as a ligand, and triethylamine or ammonia as a modifier to control the macroscopic size of the crystals. By combining the coordination properties of the pyridine group with the metal ion, a rapid reaction is achieved to obtain highly crystalline and large-sized MOFs material crystals. The MOFs metal framework material has a novel structure, a stable skeleton, and contains abundant nitrogen-containing ligands and unsaturated metal sites within the crystals, enabling direct capture of carbon dioxide gas molecules from the air. Based on this specific adsorption of carbon dioxide, it exhibits a high carbon dioxide / nitrogen adsorption selectivity.

Description

Technical Field

[0001] The present invention relates to the technical field of metal organic framework materials, in particular to a copper-based metal organic framework material based on a binaphthyl skeleton, and a preparation method and application thereof. Background Art

[0002] Metal-organic frameworks (MOFs) are porous crystalline frameworks formed by coordination bonds between metal ions and organic ligands. They inherit the structural determinism, designability, tunability of pores, good stability, and easy functional group modification characteristics of crystalline functional materials. The presence of multiple unsaturated coordination sites within their structure enables them to exhibit high selectivity for specific molecules, offering broad application prospects in gas adsorption, separation, and storage. For gases of similar molecular size, such as carbon dioxide and nitrogen, the key to selective adsorption and separation using MOFs lies in the preferential interaction between the active sites within the material's cavities and the target gas molecules. Furthermore, the stable structure, regular pores, and high specific surface area of MOFs further ensure the efficient and highly selective adsorption and separation of gas molecules during multiple adsorption / desorption cycles. However, applying the excellent gas adsorption properties of MOFs to practical applications requires overcoming the following limitations: 1. Breaking away from the energy-intensive solvothermal synthesis process and synthesizing the corresponding MOFs with relatively simple operations under mild conditions and in a short time; 2. Designing and synthesizing MOFs with specific capture capabilities at low concentrations, particularly for carbon dioxide molecules in air. According to the principles of framework chemistry, the structure of the organic ligand and the coordination pattern of the coordinating atoms not only determine the topology and crystallinity of MOFs, but also significantly influence their performance and the activity of unsaturated coordination. Therefore, selecting suitable ligands is a key breakthrough in simplifying crystal synthesis conditions and regulating the adsorption selectivity of materials. Chinese patent publication number CN106279213B discloses a highly stable copper-based metal-organic framework material, its preparation method, and application. Using 4,4-bipyridine and disodium 1,2-ethanedisulfonate as ligands, the prepared copper-based metal-organic framework material has the characteristics of good stability and excellent selectivity for guest molecules. However, this patent requires the additional addition of sulfonic acid ligands and does not exhibit good adsorption selectivity for carbon dioxide / nitrogen. Summary of the Invention

[0003] The invention solves the problem that the existing metal frame material has poor gas adsorption and separation performance for carbon dioxide and nitrogen.

[0004] The technical solution of the present invention includes a method for preparing a copper-based metal organic framework material based on a binaphthyl skeleton, comprising the following steps:

[0005] S1: Add metallic copper salt to distilled water and stir to dissolve to obtain solution A.

[0006] S2: Add pyridylbinaphthyl ligand to N,N-dimethylformamide, stir and dissolve, and obtain solution B.

[0007] S3: Solution A is added dropwise to solution B, and a regulator is added after stirring to mix. The mixture is kept warm at 35-50°C for 12-24 hours, filtered, washed, dried, and vacuum activated at 120-130°C for 4-6 hours to obtain a copper-based metal organic framework material based on a binaphthyl skeleton.

[0008] Among them, the structural formula of the pyridyl binaphthyl ligand is .

[0009] Preferably, the ratio of the metal copper salt, the pyridyl binaphthyl ligand, and the regulator is (3-3.3) mol:1 mol:(0.2-0.5) L.

[0010] Preferably, the metal copper salt is any one of copper nitrate, copper chloride, copper acetate, and copper sulfate.

[0011] Preferably, the regulator is triethylamine or ammonia.

[0012] Preferably, the structural formula of the copper-based metal organic framework material based on the binaphthyl skeleton includes any one of [CuL4(H2O)2](NO3)6, [CuL4(H2O)2](Cl)6, and [CuL4(H2O)2](CH3COO)6, where L is a pyridyl binaphthyl ligand.

[0013] Preferably, the copper-based metal organic framework material based on the binaphthyl skeleton is used in the gas adsorption separation of carbon dioxide and nitrogen.

[0014] Preferably, the preparation method of the pyridyl binaphthyl ligand is:

[0015] (1) Add binaphthol, potassium carbonate, and ethyl bromide to acetone, stir and react under argon atmosphere, cool, distill under reduced pressure, add distilled water, stir, filter, wash with distilled water, and dry to obtain intermediate 1. The reaction formula is:

[0016] .

[0017] (2) Add intermediate 1 to dichloromethane, stir, and then dropwise add liquid bromine in an ice-water bath. After stirring and reacting, add sodium thiosulfate aqueous solution to quench the excess bromine. Add dichloromethane for extraction. Dry the dichloromethane organic phase with anhydrous sodium sulfate. After filtering, evaporate the filtrate under reduced pressure. The crude product is separated by column chromatography to obtain intermediate 2. The reaction formula is:

[0018] .

[0019] (3) Add the intermediate 2,4-pyridineboronic acid pinacol ester, potassium phosphate, and tetrakis(triphenylphosphine)palladium to N,N-dimethylformamide, react under an argon atmosphere, and perform vacuum distillation. The crude product is separated by column chromatography to obtain a pyridylbinaphthyl ligand. The reaction formula is:

[0020] .

[0021] Preferably, the molar ratio of binaphthol, potassium carbonate and ethyl bromide in (1) is 1:(3.4-3.6):(3.429-3.7).

[0022] Preferably, the reaction temperature in (1) is 55-60°C and the reaction time is 6-8h.

[0023] Preferably, the reaction temperature in (2) is 20-25° C., and the reaction time is 10-12 h.

[0024] Preferably, in (2), the molar ratio of the intermediate 1 to the liquid bromine is 1:(5-6).

[0025] Preferably, the reaction temperature in (3) is 100-110° C., and the reaction time is 60-72 h.

[0026] Preferably, in (3), the molar ratio of the intermediate 2, 4-pyridineboronic acid pinacol ester, potassium phosphate, and tetrakis(triphenylphosphine)palladium is 1:(6-7):(6-8):(0.16-0.2).

[0027] Beneficial technical effects of the present invention: The present invention uses binaphthol, bromoethane, liquid bromine, 4-pyridine boric acid pinacol ester and the like as reactants to prepare pyridyl binaphthol ligands. Using divalent copper salts such as copper nitrate as raw materials, pyridine-functionalized binaphthol compounds as ligands, and triethylamine or ammonia water as regulators, the macroscopic size of the crystals is regulated, and the coordination between the pyridine group and the metal ion is combined to rapidly react to obtain highly crystalline and larger-sized MOFs material crystals. The preparation method of the MOFs material has a simple process, mild conditions, and is easy to scale up and synthesize. Moreover, there is no need to add sulfonic acid or carboxylic acid ligands. Only pyridine ligands are added to carry out coordination polymerization reactions to obtain pyridine copper-based MOFs materials. This method has high reference and research value for the development of rapid, efficient and large-scale preparation of MOFs materials.

[0028] The copper-based metal framework material prepared by this invention has a novel structure, a stable skeleton, and abundant nitrogen-containing ligands and unsaturated metal sites within the crystal. Single crystal structure analysis reveals that the unsaturated sites of this MOF crystal material can directly capture carbon dioxide gas molecules from the air, indicating that the metal framework material has a specific adsorption effect on carbon dioxide. This provides a new strategy for the design and synthesis of MOFs materials for direct air capture of carbon dioxide. Based on this specific adsorption of carbon dioxide, the MOF material achieves a high carbon dioxide / nitrogen adsorption selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a diagram of the asymmetric unit structure of the copper-based metal-organic framework material based on the binaphthyl skeleton of Example 3.

[0030] Figure 2 This is the in-situ adsorption diagram of carbon dioxide by the copper-based metal-organic framework material based on the binaphthyl skeleton of Example 3.

[0031] Figure 3 This is a three-dimensional structural diagram of the copper-based metal-organic framework material based on the binaphthyl skeleton of Example 3.

[0032] Figure 4 This is the thermogravimetric curve of the copper-based metal organic framework material based on the binaphthyl skeleton of Example 3.

[0033] Figure 5 This is the gas adsorption-desorption curve of the copper-based metal organic framework material based on the binaphthyl skeleton of Example 3 at 273K.

[0034] Figure 6 This is the gas adsorption-desorption curve of the copper-based metal organic framework material based on the binaphthyl skeleton of Example 3 at 298K.

[0035] Figure 7 This is the gas IAST selectivity of the copper-based metal organic framework material based on the binaphthyl skeleton in Example 3 at 273K.

[0036] Figure 8 Gas IAST selectivity of the binaphthyl skeleton-based copper-based metal-organic framework material of Example 3 at 298K. DETAILED DESCRIPTION

[0037] The present invention is further illustrated below with reference to specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, modifications of various equivalent forms of the present invention made by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0038] Example 1:

[0039] (1) 70 mmol of binaphthol (CAS registration number 18531-99-2), 238 mmol of potassium carbonate, and 240 mmol of bromoethane were added to 300 mL of acetone. Under an argon atmosphere, the mixture was stirred at 55°C and refluxed for 8 h. The mixture was then distilled under reduced pressure, 2 L of distilled water was added, and the mixture was stirred for 6 h. The mixture was filtered, washed, and dried to obtain intermediate 1 with a yield of 98.6%. The structural formula is .

[0040] (2) Add 20 mmol of intermediate 1 to 100 mL of dichloromethane, stir, then dropwise add 100 mmol of liquid bromine in an ice-water bath, stir and react at 25°C for 10 h, add sodium thiosulfate aqueous solution to quench the excess bromine, extract, and separate the crude product by column chromatography. Elution with a mixed solution of petroleum ether and ethyl acetate gives intermediate 2 in a yield of 59.5%. The structural formula is .

[0041] (3) 10 mmol of intermediate 2, 60 mmol of 4-pyridineboronic acid pinacol ester, 60 mmol of potassium phosphate, and 2 mmol of tetrakis(triphenylphosphine)palladium were added to 100 mL of N,N-dimethylformamide. The mixture was stirred at 100 °C for 72 h under an argon atmosphere. The mixture was distilled under reduced pressure and the crude product was separated by column chromatography. The mixture was eluted with a mixed solution of dichloromethane and methanol to obtain a pyridylbinaphthyl ligand with a yield of 75.3%. The structural formula is .

[0042] Example 2:

[0043] (1) 70 mmol of binaphthol (CAS registration number 18531-99-2), 252 mmol of potassium carbonate, and 259 mmol of ethyl bromide were added to 300 mL of acetone. Under an argon atmosphere, the mixture was stirred at 60°C and refluxed for 6 h. The mixture was then distilled under reduced pressure, 2 L of distilled water was added, and the mixture was stirred for 6 h. The mixture was filtered, washed, and dried to obtain intermediate 1 with a yield of 95.2%.

[0044] (2) 20 mmol of intermediate 1 was added to 100 mL of dichloromethane. After stirring, 120 mmol of liquid bromine was added dropwise in an ice-water bath. The reaction was stirred at 20°C for 12 h. An aqueous sodium thiosulfate solution was added to quench the excess bromine. The crude product was extracted and separated by column chromatography. The mixture was eluted with a mixed solution of petroleum ether and ethyl acetate to obtain intermediate 2 in a yield of 66.9%.

[0045] (3) 10 mmol of intermediate 2, 70 mmol of 4-pyridineboronic acid pinacol ester, 80 mmol of potassium phosphate, and 1.6 mmol of tetrakis(triphenylphosphine)palladium were added to 100 mL of N,N-dimethylformamide. The mixture was stirred at 110 °C under an argon atmosphere for 60 h. The mixture was distilled under reduced pressure and the crude product was separated by column chromatography and eluted with a mixed solution of dichloromethane and methanol to obtain a pyridylbinaphthyl ligand with a yield of 71.7%.

[0046] Example 3:

[0047] (1) Add 3 mmol of copper nitrate to 1.5 mL of distilled water and stir to dissolve to obtain solution A.

[0048] (2) Add 1 mmol of pyridylbinaphthyl ligand (prepared in Example 1) to 10 mL of N,N-dimethylformamide and stir to dissolve to obtain solution B.

[0049] (3) Solution A was added dropwise to solution B, stirred and mixed, and then 0.2 mL of ammonia water (20% by mass) was added. The mixture was kept at 35°C for 24 h, filtered, washed with a 1:1 volume ratio of acetone aqueous solution, dried, and finally activated at 120°C for 6 h under vacuum conditions to obtain a copper-based metal-organic framework material based on a binaphthyl skeleton. The structural formula is [CuL4(H2O)2](NO3)6, where L is a pyridyl binaphthyl ligand.

[0050] Figure 1 This is a diagram of the asymmetric unit structure of a copper-based metal-organic framework material based on a binaphthyl skeleton; Figure 3 It is a three-dimensional structural diagram of the metal framework material; it proves that copper nitrate and pyridyl binaphthyl ligand react to produce a copper-based metal-organic framework material based on the binaphthyl skeleton. Figure 2 This is the in-situ adsorption diagram of carbon dioxide by metal framework materials. It contains rich nitrogen-containing ligands and unsaturated metal sites, which can directly capture carbon dioxide gas molecules from the air, indicating that metal framework materials have a specific adsorption effect on carbon dioxide. Figure 4 This is the thermogravimetric curve of the copper-based metal-organic framework material based on the binaphthyl skeleton, which shows that the metal framework material has good thermal stability.

[0051] Example 4:

[0052] (1) Add 3.3 mmol of copper acetate to 1.5 mL of distilled water and stir to dissolve to obtain solution A.

[0053] (2) Add 1 mmol of pyridylbinaphthyl ligand (prepared in Example 1) to 10 mL of N,N-dimethylformamide and stir to dissolve to obtain solution B.

[0054] (3) Solution A was added dropwise to solution B, stirred and mixed, and then 0.5 mL of triethylamine (a regulator) was added and the mixture was kept at 50°C for 12 h. The mixture was filtered, washed with a 1:1 volume ratio of acetone aqueous solution, dried, and finally activated at 120°C for 6 h under vacuum conditions to obtain a copper-based metal-organic framework material based on a binaphthyl skeleton. The structural formula is [CuL4(H2O)2](CH3COO)6, where L is a pyridyl binaphthyl ligand.

[0055] Example 5:

[0056] (1) Add 3 mmol of copper chloride to 1.5 mL of distilled water and stir to dissolve to obtain solution A.

[0057] (2) Add 1 mmol of pyridylbinaphthyl ligand (prepared in Example 1) to 10 mL of N,N-dimethylformamide and stir to dissolve to obtain solution B.

[0058] (3) Solution A was added dropwise to solution B, stirred and mixed, and then 0.2 mL of ammonia water (20% by mass) was added. The mixture was kept at 45°C for 24 h, filtered, washed with a 1:1 volume ratio of acetone aqueous solution, dried, and finally activated at 130°C for 4 h under vacuum conditions to obtain a copper-based metal-organic framework material based on a binaphthyl skeleton. The structural formula is [CuL4(H2O)2](Cl)6, where L is a pyridylbinaphthyl ligand.

[0059] Comparative Example 1:

[0060] (1) Add 3 mmol of copper nitrate to 1.5 mL of distilled water and stir to dissolve to obtain solution A.

[0061] (2) Add 1 mmol of pyridylbinaphthyl ligand (prepared in Example 1) to 10 mL of N,N-dimethylformamide and stir to dissolve to obtain solution B.

[0062] (3) Solution A was added dropwise to solution B, stirred and mixed, and then kept warm at 35°C for 24 h. The mixture was filtered, washed with an acetone aqueous solution with a volume ratio of 1:1, dried, and finally activated at 120°C for 6 h under vacuum conditions to obtain a copper-based metal-organic framework material based on a binaphthyl skeleton.

[0063] Comparative Example 2: In this comparative example, conventional trimesic acid and 4,4'-bipyridine were used as ligands to prepare MOFs materials.

[0064] To 9 mL of N,N-dimethylformamide and 9 mL of ethanol, 0.4 g of copper nitrate trihydrate, 0.095 g of trimesic acid, and 4,4'-bipyridine were added, stirred, and poured into a reactor. The mixture was reacted at 120°C for 12 hours. After filtration, the mixture was washed with an acetone aqueous solution with a volume ratio of 1:1, dried, and finally activated at 120°C under vacuum conditions for 6 hours to obtain MOFs material.

[0065] Comparative Example 3: In this comparative example, conventional 2,2'-bipyridine-4,4'-dicarboxylic acid was used as a ligand to prepare MOFs material.

[0066] 0.14 mmol copper nitrate and 0.1 mol 2,2'-bipyridine-4,4'-dicarboxylic acid were added to a mixed solvent of 1 mL N,N-dimethylacetamide, 1 mL acetonitrile and 1 mL water, stirred and poured into a reactor, reacted at 125°C for 36 hours, cooled, filtered, washed with ethanol, dried, and finally activated at 120°C under vacuum conditions for 6 hours to obtain MOFs material.

[0067] The nitrogen adsorption and desorption curves and carbon dioxide adsorption and desorption curves of MOFs materials at 273K and 298K were measured using a gas adsorption instrument. The test results are shown in the following table and Figure 5-8 .

[0068] Table 1 Gas adsorption capacity test at temperature 273K and relative pressure P / P0 of 1

[0069] Carbon dioxide adsorption capacity (mL / g) Nitrogen adsorption capacity (mL / g) Example 3 25.95 17.04 Example 4 25.33 17.08 Example 5 24.27 16.92 Comparative Example 1 21.16 14.56 Comparative Example 2 16.30 12.21 Comparative Example 3 13.19 9.65

[0070] Table 2 Gas adsorption capacity test at temperature 298K and relative pressure P / P0 of 1

[0071] Carbon dioxide adsorption capacity (mL / g) Nitrogen adsorption capacity (mL / g) Example 3 11.58 0.80 Example 4 11.45 0.88 Example 5 10.67 0.73 Comparative Example 1 9.86 0.69 Comparative Example 2 7.04 0.62 Comparative Example 3 5.62 0.49

[0072] From Table 1, Table 2 and Figure 5-6 It can be seen that the copper-based metal-organic framework materials based on the binaphthyl skeleton of Examples 3-5 have an adsorption capacity for carbon dioxide of 24.27-25.95 mL / g at 273 K and a relative pressure of 1. At 298 K and a relative pressure of 1, the adsorption capacity for carbon dioxide reaches 10.67-11.58 mL / g, which is significantly higher than that of Comparative Examples 1-3.

[0073] Depend on Figure 7 and Figure 8 It can be seen that the metal frame material prepared in Example 3 exhibits good gas IAST selectivity at temperatures of 273K and 298K in a mixed gas with a volume ratio of carbon dioxide to nitrogen of 1:9 or 2:8.

[0074] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. Application of a copper-based metal organic framework material based on a binaphthyl skeleton in the gas adsorption separation of carbon dioxide and nitrogen, characterized in that: The preparation method of the copper-based metal organic framework material based on the binaphthyl skeleton comprises: S1: Add metallic copper salt to distilled water and stir to dissolve to obtain solution A; S2: Add pyridylbinaphthyl ligand to N,N-dimethylformamide, stir and dissolve to obtain solution B; S3: adding solution A dropwise to solution B, stirring and mixing, adding a regulator, keeping the mixture warm for reaction, filtering, washing, drying, and vacuum activating to obtain a copper-based metal organic framework material based on a binaphthyl skeleton; The structural formula of the pyridylbinaphthyl ligand is .

2. The use of the copper-based metal organic framework material based on the binaphthyl skeleton according to claim 1 in the gas adsorption separation of carbon dioxide and nitrogen, characterized in that: The ratio of the metal copper salt, the pyridyl binaphthyl ligand, and the regulator is (3-3.3) mol:1 mol:(0.2-0.5) L; the metal copper salt is any one of copper nitrate, copper chloride, copper acetate, and copper sulfate.

3. The use of the copper-based metal organic framework material based on the binaphthyl skeleton in the gas adsorption separation of carbon dioxide and nitrogen according to claim 2, characterized in that: The regulator is triethylamine or ammonia water.

4. The use of the copper-based metal organic framework material based on the binaphthyl skeleton in the gas adsorption separation of carbon dioxide and nitrogen according to claim 1, characterized in that: The temperature of the heat preservation reaction in S3 is 35-50° C. and the time is 12-24 hours; the temperature of the vacuum activation is 120-130° C. and the time is 4-6 hours.

5. The use of the copper-based metal organic framework material based on the binaphthyl skeleton in the gas adsorption separation of carbon dioxide and nitrogen according to claim 1, characterized in that: The structural formula of the copper-based metal organic framework material based on the binaphthyl skeleton includes any one of [CuL4(H2O)2](NO3)6, [CuL4(H2O)2](Cl)6, and [CuL4(H2O)2](CH3COO)6, where L is a pyridyl binaphthyl ligand.

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