Zinc metal organic framework material based on pyridine functionalized pyrazole ligand as well as preparation and application of zinc metal organic framework material

Abstract

The invention discloses a metal organic framework material based on pyridine functionalized zinc as well as preparation and application thereof, and belongs to the technical field of crystalline materials. The chemical formula is [Zn (DPP)], and DPP is an organic ligand 3, 5-bis (1H-pyrazole-4-yl) pyridine. The synthesis of the metal-organic framework is as follows: under a closed condition, an organic ligand 3, 5-di (1H-pyrazol-4-yl) pyridine (DPP) and zinc nitrate are subjected to solvothermal reaction in a mixed solution of N, N-dimethylformamide and hydrochloric acid to obtain crystals of the metal-organic framework material; the metal organic framework material shows selective adsorption on CO2.

Description

Technical Field

[0001] The present invention belongs to the technical field of crystalline materials, and relates to metal-organic coordination polymer materials, and is characterized by a metal-organic framework material of pyridine-functionalized pyrazole zinc, a preparation method thereof, and an application research thereof. Background Art

[0002] The greenhouse effect is a serious environmental problem faced by mankind. As the main greenhouse gas, it far exceeds the load of the natural carbon cycle. Due to the dominant position of fossil fuels in the current energy framework, about 60% of carbon dioxide emissions are contributed by power plants. Therefore, there is an urgent need to develop an effective and environmentally friendly technology to capture carbon dioxide from the flue gas emitted by power plants burning fossil fuels. Among various adsorption technologies, porous solid adsorbents are favored due to their high efficiency, energy saving, and easy recycling.

[0003] Metal-organic frameworks (MOFs) are prominent solid adsorbents that combine well-defined adsorption sites, fine-tuned pore sizes, and decorated internal functions to achieve strong binding affinity, high selectivity, large capacity, and low regeneration energy for CO 2 capture. Incorporating functional sites and tuning pore size / shape in MOFs are two powerful strategies to achieve this goal. However, it remains challenging to develop target materials with extremely high CO 2 capture capacity / selectivity and moderate CO 2 adsorption enthalpy. Summary of the Invention

[0004] The purpose of the present invention is to provide a metal-organic framework material of zinc based on a pyridine-functionalized pyrazole ligand, a preparation method thereof, and an application thereof.

[0005] A metal-organic framework material of zinc based on a pyridine-functionalized pyrazole ligand according to the present invention is characterized in that its chemical formula is [Zn(DPP)]·H 2 DPP is an organic ligand 3,5-bis(1H-pyrazol-4-yl)pyridine.

[0006] The metal-organic framework material has a three-dimensional framework structure. From the perspective of framework connection construction, the crystal structure of the metal-organic framework belongs to the cubic crystal system, the space group is I4 1 md, and the unit cell parameters are: α = β = γ = 90°.

[0007] In the metal-organic framework, the Zn atoms are tetracoordinated, and the surrounding coordinated atoms are 4 nitrogen atoms, and these coordinated nitrogen atoms come from four different pyrazole ligands.

[0008] In the metal-organic framework, there are three bond lengths of Zn-N bonds, which are respectively and One-dimensional (1D) infinite zinc-based chains serve as its secondary building units (SBUs), which are interconnected by double-wall bispyrazole ligands to ultimately form a three-dimensional framework with one-dimensional channels.

[0009] The organic ligand is 3,5-bis(1H-pyrazol-4-yl)pyridine (H 2 DPP), namely a ditopic pyrazole ligand, and its structural formula is shown as follows:

[0010]

[0011] This ligand contains a benzene ring and two pyrazoles; the included angle between two adjacent pyrazoles in the ligand is 120°, and the pyrazole rings are directly connected to the benzene ring.

[0012] The synthesis method of the novel ditopic pyrazole ligand of the present invention includes the following two steps:

[0013] Carbon-carbon coupling: 3,5-dibromopyridine and tert-butyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole-1-carboxylate are in 1,4-dioxane and water, potassium carbonate and tetrakis(triphenylphosphine)palladium are added, sealed, protected by inert gas, reacted at room temperature, and then reacted for at least 20 hours. After completion, the solvent is evaporated, and extracted with dichloromethane and water. The organic layer is dried with anhydrous magnesium chloride, and after the solvent is evaporated, it is purified by column chromatography (PE:EA = 10:1 to 2:1) to obtain 3,5-bis(1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-4-yl)pyridine.

[0014] Deprotection: 3,5-bis(1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-4-yl)pyridine and hydrochloric acid are heated under reflux in a mixed solution of ethanol / water for deprotection to obtain 3,5-bis(1H-pyrazol-4-yl)pyridine.

[0015] The synthesis method of the metal-organic framework material of the present invention includes the following steps:

[0016] Under sealed conditions, 3,5-bis(1H-pyrazol-4-yl)pyridine (H 2 DPP) and zinc nitrate (Zn(NO 3 )) 2 ) are in a mixed solution of N,N-dimethylformamide (DMF) and hydrochloric acid, and the crystal of the metal-organic framework is obtained through a solvothermal reaction.

[0017] Further preferably, under sealed conditions, 3,5-bis(1H-pyrazol-4-yl)pyridine (H 2 DPP) and zinc nitrate (Zn(NO 3 ))2 ) The molar ratio is 1:1; the mixed solution of N,N-dimethylformamide (DMF) and hydrochloric acid is a solution with a volume ratio of DMF to 0.01 - 1 M dilute hydrochloric acid of 20:1 to 4:1.

[0018] The organic ligand synthesized in the present invention belongs to a novel bis-pyrazole ligand. The metal-organic framework constructed in the present invention has pyridine groups, large pore size and pore volume, making the MOFs have potential applications in the selective capture of carbon dioxide in nitrogen. Description of the Drawings

[0019] Figure 1 It is a synthetic route diagram of the bis-pyrazole ligand for synthesizing the metal-organic framework.

[0020] Figure 2 It is a secondary building unit diagram of the metal-organic framework. (a) corresponds to the coordination environment diagram of zirconium, and (b) corresponds to the ligand.

[0021] Figure 3 It is a three-dimensional structure schematic diagram of the metal-organic framework.

[0022] Figure 4 It is an adsorption isotherm diagram of the metal-organic framework material for carbon dioxide and nitrogen at 298 K. Detailed Embodiments

[0023] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited to the following embodiments.

[0024] Example 1:

[0025] Under nitrogen protection, 3,5-dibromopyridine (18.0 mmol), tert-butyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole-1-carboxylate (50.0 mmol), potassium carbonate (0.2 mmol), tetrakis(triphenylphosphine)palladium (0.18 mmol), and 1,4-dioxane (200 mL) and water (50 mL) were added to a 500 mL round-bottom flask, and the reaction system was stirred at room temperature for 24 hours. After the reaction was completed, the solvent of the reaction system was rotary evaporated, and the residue was dissolved in dichloromethane (500 mL), washed successively with water (500 mL × 2) and saturated brine (500 mL), and dried over anhydrous Mg 2 SO 4 After drying, it was filtered and concentrated. The crude product was purified by column chromatography (SiO 2 , petroleum ether / ethyl acetate = 20:1 to 1:2), and after concentration, a yellow viscous substance 3,5-bis(1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-4-yl)pyridine was obtained (yield 76%).

[0026] Example 2:

[0027] The yellow viscous substance 3,5-bis(1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-4-yl)pyridine obtained in the previous step and concentrated hydrochloric acid (20 mL) were placed in an ethanol (50 mL) solution and stirred under reflux for 12 hours. After the reaction was completed, the organic solvent was removed by rotary evaporation. The remaining solid was dispersed in 200 mL of water, and then 2M hydrochloric acid aqueous solution was added dropwise to adjust the pH to 9. The resulting suspension was filtered, and the solid was washed with water (100 mL×3) and then dried in vacuo at 60 °C to obtain the white solid 3,5-bis(1H-pyrazol-4-yl)pyridine (H 2 DPP, with a yield of 70%). 1 H NMR (DMSO-d 6 , 400 MHz) δ 13.04 (s, 2H), 9.69 (s, 2H), 8.43 (s, 1H), 7.88 (s, 4H).

[0028] Example 3

[0029] Weigh the ligand H 2 DPP (0.06 mmol) and Zn(NO 3 ) 2 (0.06 mmol) and place them in a 4 mL glass vial. Add a DMF solution with a volume ratio of (2:1) and 0.1M dilute hydrochloric acid. Then seal the vial and place it in an ultrasonic bath and ultrasonicate for 5 minutes at room temperature. After sealing, place the vial in an oven at 120 °C and react for 10 hours. After the reaction is completed, turn off the oven. After cooling to room temperature, filter and collect the solid particles obtained in the vial, and then wash them successively with DMF, H 2 O and EtOH (5 mL×3). Colorless rod-shaped crystals (Zn(DPP)) were obtained by observing under a microscope (yield: 64%, based on the H 2 DPP ligand).

[0030] Example 4

[0031] Weigh the ligand H 2 DPP (0.06 mmol) and Zn(NO 3 ) 2 (0.06 mmol) and place them in a 4 mL glass vial. Add a DMF solution with a volume ratio of (3:1) and 1M dilute nitric acid. Then seal the vial and place it in an ultrasonic bath and ultrasonicate for 5 minutes at room temperature. After sealing, place the vial in an oven at 120 °C and react for 10 hours. After the reaction is completed, turn off the oven. After cooling to room temperature, filter and collect the solid particles obtained in the vial, and then wash them successively with DMF, H 2Washed with O and EtOH (5 mL × 3), and colorless rod-shaped crystals (Zn(DPP)) were obtained by microscopic observation (yield: 72%, based on the H 2 DPP ligand).

[0032] The test results of the products obtained in the above examples are the same, as shown below:

[0033] (1) Determination of crystal structure:

[0034] Powders of appropriate size were selected, and data were collected at 298 K using a PANalytical X’Pert PRO high-resolution powder diffractometer. The data collection used Cu-Kα target radiation monochromatized by a graphite monochromator. The absorption correction of the data was completed using the SCALE3 ABSPACK software. The crystal structure was solved by the direct method using the SHELXTL-97 program. First, the coordinates of all non-hydrogen atoms were determined by the difference function method and the least-squares method, and the positions of hydrogen atoms were obtained by the theoretical hydrogenation method. Then, the crystal structure was refined using SHELXTL-97. The structure diagram is shown in Figures 2 to 4 . The crystallographic data are shown in Table 1.

[0035] Table 1 Crystallographic data of the metal-organic framework material

[0036]

[0037] Figure 1 The synthetic route diagram of the ditopic pyrazole ligand shows that: First, 3,5-dibromopyridine and tert-butyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole-1-carboxylate were added with potassium carbonate and tetrakis(triphenylphosphine)palladium in 1,4-dioxane and water, sealed, evacuated, and protected by an inert gas, and reflux reaction could obtain 3,5-bis(1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-4-yl)pyridine; then 3,5-bis(1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-4-yl)pyridine and 2 M hydrochloric acid were heated under reflux in an ethanol / water solution to remove the protection to obtain 3,5-bis(1H-pyrazol-4-yl)pyridine.

[0038] Figure 2 The structure diagram shows that: The inorganic nodes contained in the framework structure are zinc chains, and the organic ligand is 3,5-bis(1H-pyrazol-4-yl)pyridine.

[0039] Figure 3 The structure diagram shows: The three-dimensional packing diagram in this metal-organic framework.

[0040] (2) Adsorption of carbon dioxide and nitrogen

[0041] Figure 4 The following is the adsorption isotherm of the material of the present invention for carbon dioxide and nitrogen. It can be seen that the material can selectively adsorb carbon dioxide.

Claims

1. A zinc metal-organic framework material based on pyridine-functionalized pyrazole ligands, characterized in that: The chemical formula is [Zn(DPP)], and H2DPP is the organic ligand 3,5-di(1H-pyrazol-4-yl)pyridine.

2. A zinc metal-organic framework material based on pyridine-functionalized pyrazole ligands according to claim 1, characterized in that: The metal-organic framework material has a three-dimensional framework structure. From the perspective of framework connection and construction, the crystal structure of the metal-organic framework belongs to the cubic crystal system, the space group is I41md, and the unit cell parameters are: α=β=γ=90°.

3. A zinc metal-organic framework material based on pyridine-functionalized pyrazole ligands according to claim 1, characterized in that: In this metal-organic framework, the Zn atom is tetracoordinated, and the surrounding coordinated nitrogen atoms are from four different pyrazole ligands. In this metal-organic framework, there are three Zn-N bond lengths, which are and Based on zinc one-dimensional (1D) infinite chains as its secondary building units (SBUs), these units are interconnected by double-walled bipyrazole ligands to finally form a 3D framework with 1D channels.

4. A zinc metal-organic framework material based on pyridine-functionalized pyrazole ligands according to claim 1, characterized in that: The organic ligand is 3,5-di(1H-pyrazol-4-yl)pyridine (H2DPP), i.e., a bipyrazole ligand, and the structural formula is as follows: The ligand comprises a benzene ring and two pyrazoles; the angle between two adjacent pyrazoles in the ligand is 120°, and the pyrazole ring is directly connected to the benzene ring.

5. A zinc metal-organic framework material based on pyridine-functionalized pyrazole ligands according to claim 1, characterized in that: The synthesis method of the two-headed pyrazole ligand comprises the following two steps: CC coupling: 3,5-dibromopyridine and tert-butyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)-1H-pyrazole-1-carboxylate are added to 1,4-dioxane and water, potassium carbonate and tetrakistriphenylphosphine palladium are added, sealed, protected by inert gas, reacted at room temperature, and then reacted for at least 20 hours. After completion, the solvent is dried by spin drying and extracted with dichloromethane and water. The organic layer is dried over anhydrous magnesium chloride, the solvent is dried by spin drying and purified by column chromatography (PE:EA=10:1~2:1) to obtain 3,5-di(1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-4-yl)pyridine; Deprotection: 3,5-di(1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-4-yl)pyridine and hydrochloric acid are heated under reflux in a mixed solution of ethanol / water for deprotection to obtain 3,5-di(1H-pyrazol-4-yl)pyridine.

6. The method for preparing the zinc metal-organic framework material of pyridine-functionalized pyrazole ligand according to any one of claims 1 to 5, characterized in that: The following steps are involved: Under sealed conditions, 3,5-di(1H-pyrazol-4-yl)pyridine (H2DPP) and zinc nitrate (Zn(NO3)2) were reacted in a mixed solution of N,N-dimethylformamide (DMF) and hydrochloric acid to obtain the crystals of the metal-organic framework via a solvothermal reaction.

7. The method according to claim 6, characterized in that The molar ratio of 3,5-di(1H-pyrazol-4-yl)pyridine (H2DPP) to zinc nitrate (Zn(NO3)2) is 1:(1-4), each 0.05 mmol of zinc nitrate corresponds to 1 mL-8 mL of DMF and 300 ul-800 ul of dilute acid, the temperature of the thermal reaction is 80°C-150°C, and the reaction time is 8-48 hours.

8. Use of the zinc metal-organic framework material based on pyridine-functionalized pyrazole ligands as claimed in any one of claims 1 to 6 in the selective capture of carbon dioxide in nitrogen.

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