9,9'-spirobifluorene-containing ultramicroporous metal-organic frameworks and methods of preparation

Abstract

The present application belongs to the technical field of metal-organic framework materials, and particularly relates to a kind of super-microporous metal-organic framework materials containing 9,9'-spirobifluorene and a preparation method thereof.The present application takes SHU-1 (chemical formula is {[(CH3)2NH2]2[(Ca4O)L4(H2O)4]·6DMF} ∞ ) as raw material, and through the method of water vapor diffusion, under the induction of water vapor, SHU-1 is subjected to structure transformation to obtain super-microporous metal-organic framework materials containing 9,9'-spirobifluorene.The preparation method is simple in operation, mild in condition, and friendly to environment, and the yield is between 70-87%.The super-microporous metal-organic framework materials containing 9,9'-spirobifluorene of the present application are formed by connecting calcium oxygen polyhedron helical chain and spirobifluorene dicarboxylic acid rigid ligand, have three-dimensional framework structure, porosity is about 21%, BET specific surface area is 187m 2 / g, pore volume is 0.14cm 3 / g, and pore size is 0.6nm.The super-microporous metal-organic framework materials containing 9,9'-spirobifluorene have potential application prospect in CO2 gas adsorption and CO2 / CH4 mixed gas separation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metal-organic framework materials, and particularly relates to a 9,9'-spirobifluorene-containing ultramicroporous metal-organic framework material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of industrial production, higher requirements are put forward for gas adsorption and separation, and it is of great industrial significance to develop more efficient porous materials for gas adsorption and separation. On the one hand, porous materials are required to have ultralarge specific surface area and micropores with large pore size to realize high-density storage of gas. On the other hand, porous materials with ultramicropores have gradually attracted people's attention because they have better screening effect and can play a good role in gas separation. There are still some difficulties in the preparation of ultramicroporous materials, which limit the application of this kind of materials in the field of gas adsorption and separation.

[0003] In the past three decades, metal-organic framework materials (MOFs) have attracted widespread attention as a new type of porous material. Compared with other porous materials, MOFs have unique advantages and broad application prospects in the field of gas adsorption and separation due to their high porosity, high specific surface area and excellent structural tunability. The 9,9'-spirobifluorene structural unit has strong rigidity and has been used to construct MOFs materials. By reasonably selecting metal nodes, MOFs containing 9,9'-spirobifluorene structural units can realize the fine-tuning of pore structure, so that ultramicropores are obtained in the structure of MOFs, making this kind of MOFs become an ideal candidate material for gas storage and separation. The preparation of MOFs often involves hydrothermal and solvothermal conditions, and sometimes simple stirring reaction conditions are also used. These preparation conditions usually require energy consumption and may cause environmental pollution, so it is urgent to develop a simple, energy-saving and environmentally friendly MOFs synthesis method. SUMMARY

[0004] In order to solve the problems in the prior art, the purpose of the present application is to overcome the shortcomings of the prior art and provide a 9,9'-spirobifluorene-containing ultramicroporous metal-organic framework material. The calcium-oxygen polyhedral helical chain and the rigid spirobifluorene ligand in the ultramicroporous metal-organic framework material are connected to form a MOF with a three-dimensional structure, which has high stability and exhibits constant porosity, and has potential application prospects in CO2 gas adsorption and CO2 / CH4 mixed gas separation.

[0005] To achieve the above object, the present application adopts the following technical solution: A kind of 9,9'-spirobifluorene-containing supermicroporous metal-organic framework material, the 9,9'-spirobifluorene-containing supermicroporous metal-organic framework material has three-dimensional structure, which is connected by spiral chain containing calcium oxygen polyhedron and spirobifluorene rigid ligand, and its chemical formula is {[Ca6L6(DMF)2(H2O)8]·2DMF·3H2O} ∞ Wherein L represents organic ligand, and DMF represents N,N-dimethylformamide;

[0006] The organic ligand L is 9,9'-spirobifluorene-2,2'-dicarboxylic acid, and its structural formula is as follows

[0007]

[0008] Further improvement of the 9,9'-spirobifluorene-containing supermicroporous metal-organic framework material:

[0009] Preferably, the 9,9'-spirobifluorene-containing supermicroporous metal-organic framework material is crystallized in monoclinic crystal system C2 / c space group, and the calcium oxygen polyhedron in the form of pentagonal bipyramid is connected to each other by the way of common side to form one-dimensional spiral chain in two orientations, the aromatic ring of the spirobifluorene dicarboxylic acid ligand separates the two spiral chains, there is C-H…π interaction between the aromatic rings, and the spiral chain and the rigid ligand are connected to form a three-dimensional structure.

[0010] Preferably, in the 9,9'-spirobifluorene-containing supermicroporous metal-organic framework material, the spirobifluorene dicarboxylic acid and the one-dimensional spiral chain enclose a one-dimensional channel, and the size of the channel opening is It belongs to supermicropore.

[0011] Preferably, the 9,9'-spirobifluorene-containing supermicroporous metal-organic framework material is applied to CO2 gas adsorption and CO2 / CH4 mixed gas separation.

[0012] The second object of the present application is to provide a preparation method of the above-mentioned 9,9'-spirobifluorene-containing supermicroporous metal-organic framework material, which comprises the following steps:

[0013] S1, 30-58 mg of raw material SHU-1 with chemical formula {[[(CH3)2NH2]2[(Ca4O)L4(H2O)4]·6DMF} ∞ is weighed and added into a 1.5 mL Eppendorf plastic centrifuge tube;

[0014] 10-20 ml of deionized water is added into a 100 mL Schott Duran blue cover bottle, and a 10 mL glass sample bottle is placed in the bottle; the Eppendorf plastic centrifuge tube containing SHU-1 is placed in the glass sample bottle with the opening exposed, then the cover of the Schott Duran blue cover bottle is tightly screwed, and the bottle is placed;

[0015] S2, during the standing process, the centrifugal tube containing the raw material SHU-1 is taken out every 1-2 days, and the raw material is ground and then placed back into the Schott Duran blue cap bottle for continuous standing; the standing-grinding operation is repeated until the end of 1-2 weeks, and the sample is taken out from the centrifugal tube and dried, thereby obtaining the super-microporous metal-organic framework material containing 9,9'-spirobifluorene, denoted as SHU-1c.

[0016] The beneficial effects of the present application compared with the prior art are:

[0017] 1) The present application provides a super-microporous metal-organic framework material containing 9,9'-spirobifluorene (SHU-1c), and the 9,9'-spirobifluorene structural unit has strong rigidity. By reasonably selecting the metal nodes to construct the MOFs material, the pore structure can be fine-tuned, so that super-micropores are obtained in the MOFs structure, and this kind of MOFs becomes an ideal candidate material for gas storage and separation. The calcium-oxygen polyhedral substructure unit and the spirobifluorene dicarboxylic acid ligand in the structure of SHU-1c are crystallized in a monoclinic C2 / c space group, and form a three-dimensional structure. The calcium-oxygen polyhedral substructure unit is in a pentagonal bipyramidal configuration, and is connected to each other through a common side to form a one-dimensional spiral chain, and there are two orientations of left-handed and right-handed spiral chains in the one-dimensional spiral chain. The spirobifluorene dicarboxylic acid ligand and the one-dimensional chain with two spiral orientations are connected to form a three-dimensional structure, and the one-dimensional channel formed by the spirobifluorene dicarboxylic acid and the one-dimensional spiral chain has an opening size of which belongs to the range of super-micropores. Due to the support of the spiral chain and the rigid ligand, SHU-1c has good structural stability. After removing the guest and the coordination solvent, the porosity is about 21%, which shows constant pore properties, the BET specific surface area is 187 m 2 / g, the pore volume is 0.14 cm 3 / g, and the pore size is

[0018] 2) The present application provides a method for preparing a super-microporous metal-organic framework material containing 9,9'-spirobifluorene, which involves a structure transformation under water vapor induction conditions: SHU-1 (chemical formula is {[(CH3)2NH2]2[(Ca4O)L4(H2O)4]·6DMF} ∞The polycrystal of SHU-1 is placed in a small container, and then the small container is placed in an airtight large container saturated with water vapor in an open state, water vapor diffusion is carried out, and through the induction of water vapor, SHU-1 is subjected to structural transformation, and then the target framework material SHU-1c is formed. In the whole process, no dissolution of the polycrystal occurs, and the possibility of dissolution recrystallization can be excluded. The process can be described as a structural transformation under the induction of water vapor. When a large amount of SHU-1c needs to be prepared, the parallel experiment method can be adopted, and a plurality of groups of transformations are simultaneously carried out, and the final yield is between 70-87%. The preparation method is simple in operation, mild in conditions, environmentally friendly, and high in yield, and provides a reference for synthesizing metal-organic framework materials with supermicroporous structure.

[0019] 3) The supermicroporous metal-organic framework material containing 9,9'-spirobifluorene of the present application has a novel structure, good structural stability, supermicropores, and constant pore size in the supermicropore range, and has separation capacity for CO2 / CH4 mixed gas. Under the conditions of 195K and 100kPa, the adsorption capacity of CO2 is 78cm 3 / g. When using CO2 / CH4 mixed gas (50 / 50, V / V), under the condition of a flow rate of 4.00cm 3 / min, the breakthrough time of CH4 is 12.9s / g, and the breakthrough time of CO2 is 118.1s / g, and the CO2 / CH4 separation coefficient calculated by the breakthrough experiment is 3.5. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a schematic diagram of the calcium oxygen pentagonal bipyramid, one-dimensional helical chain and one-dimensional helical chain-like orientation of the supermicroporous metal-organic framework material containing 9,9'-spirobifluorene (SHU-1c) of the present application.

[0021] Figure 2 It is a schematic diagram of the one-dimensional pore structure of the supermicroporous metal-organic framework material containing 9,9'-spirobifluorene (SHU-1c) of the present application.

[0022] Figure 3 It is an N2(77K) and CO2(195K) isotherm adsorption curve diagram of the supermicroporous metal-organic framework material containing 9,9'-spirobifluorene (SHU-1c) prepared in Example 1 of the present application.

[0023] Figure 4 It is a CO2 and CH4 isotherm adsorption curve diagram (296K) of the supermicroporous metal-organic framework material containing 9,9'-spirobifluorene (SHU-1c) prepared in Example 1 of the present application.

[0024] Figure 5Figure of multi-component gas penetration experiment of 9,9'-spirobifluorene-containing super-microporous metal-organic framework material (SHU-1c) prepared in Embodiment 1 of the present application. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below in combination with embodiments, and all other embodiments obtained by those skilled in the art without making any creative efforts on the basis of the embodiments in the present application all belong to the scope of protection of the present application.

[0026] Embodiment 1

[0027] The present embodiment provides a preparation method of 9,9'-spirobifluorene-containing super-microporous metal-organic framework material, specifically comprising the following steps:

[0028] S1, 58 mg of raw material SHU-1 with chemical formula of {[(CH3)2NH2]2[(Ca4O)L4(H2O)4]·6DMF} is weighed and added into a 1.5 mL Eppendorf centrifuge tube; ∞ S2, during the standing process, the centrifuge tube containing the raw material SHU-1 is taken out every 2 days, and the raw material is ground and then placed back into the Schott Duran blue cap bottle for continuous standing; the standing-grinding operation is repeated until the end of 2 weeks, and the sample is taken out from the centrifuge tube and dried, thereby obtaining the 9,9'-spirobifluorene-containing super-microporous metal-organic framework material, which is recorded as SHU-1c; the yield of SHU-1c is calculated to be 87%.

[0029] In a 100 mL Schott Duran blue cap bottle, 20 ml of deionized water is added, and a 10 mL glass sample bottle is placed in the bottle; the Eppendorf centrifuge tube containing SHU-1 is placed in the glass sample bottle with the opening exposed, and then the cap of the Schott Duran blue cap bottle is tightly screwed, and the bottle is left standing;

[0030] S2, during the standing process, the centrifuge tube containing the raw material SHU-1 is taken out every 2 days, and the raw material is ground and then placed back into the Schott Duran blue cap bottle for continuous standing; the standing-grinding operation is repeated until the end of 2 weeks, and the sample is taken out from the centrifuge tube and dried, thereby obtaining the 9,9'-spirobifluorene-containing super-microporous metal-organic framework material, which is recorded as SHU-1c; the yield of SHU-1c is calculated to be 87%.

[0031] In the present embodiment, the 9,9'-spirobifluorene-containing super-microporous metal-organic framework material (SHU-1c) is crystallized in a monoclinic crystal system C2 / c space group, and the cell parameters are as follows: β = 124.36 (3) o , Z = 4, D c = 1.304 g / cm 3 , F (000) = 6016.

[0032] Figure 1Schematic diagram of calcium oxypentagonal bipyramid, one-dimensional helical chain and one-dimensional helical chain-like orientation of the 9,9'-spirobifluorene-containing super-microporous metal-organic framework material (SHU-1c) of the present application. From Figure 1 It can be seen that the calcium-oxygen polyhedral substructure motif of SHU-1c is in the form of pentagonal bipyramid Figure 1 a), and 7 oxygen atoms coordinated with the calcium ion at the center of the polyhedron, of which 4 are derived from the carboxyl groups of the ligand, 2 are derived from the coordinated water, and 1 is derived from the coordinated DMF. The calcium-oxygen polyhedra in the form of pentagonal bipyramid in SHU-1c are connected to each other in a way of sharing edges, thereby forming a one-dimensional helical chain-like structure Figure 1 b), in which the distance between adjacent calcium ions is There are two orientations of helix in the one-dimensional helical chain of SHU-1c, i.e. the spatial extension direction of the helical chain is right-handed helix and left-handed helix Figure 1 c), and the two types of helical chains are equally present, so no optical rotation phenomenon is generated. The one-dimensional chains of the two helix orientations extend along the c-axis direction, and the aromatic rings of the spirobifluorene dicarboxylic acid ligand separate them, and there are C-H…π interactions between the aromatic rings.

[0033] Figure 2 Schematic diagram of the one-dimensional channel structure of SHU-1c prepared in the above Example 1. From Figure 2 It can be seen that the aromatic rings of the spirobifluorene dicarboxylic acid ligand in SHU-1c also generate one-dimensional channels while separating Figure 2 a and Figure 2 b), and the one-dimensional channels also extend along the c-axis direction, and are surrounded by the two types of helical chains and the aromatic rings of the spirobifluorene dicarboxylic acid ligand, and the DMF and water coordinated with the calcium ions extend into the inside of the channels, and the size of the opening of the channels is which belongs to the range of super-micropores Figure 2 c). It can be seen from the PLATON / SQUEEZE calculation that the porosity of SHU-1c after removing the guests and the coordinated solvent is about 21%.

[0034] Figure 3 N2(77K) and CO2(195K) isotherm curve diagram of SHU-1c prepared in the above Example 1. After activation, when the specific surface area is quantitatively tested using N2 as the probe molecule under the condition of 77K, no type I characteristic adsorption curve of micropore is observed; when CO2 is used as the probe molecule for quantitative testing, type I characteristic adsorption curve Figure 3 is obtained under the condition of 195K, which confirms the existence of super-micropores in the sample and the constant-pore nature of the sample. Through BJH method calculation, the BET specific surface area of the material prepared in Example 1 is 187 m 2 / g, and the pore volume is 0.14 cm 3 / g, with a pore size of The CO2 adsorption capacity of SHU-1c is 78 cm 3 / g at 195 K and 100 kPa.

[0035] Figure 4 The CO2 and CH4 isotherm plot of the 9,9'-spirobifluorene-containing supermicroporous metal-organic framework material (SHU-1c) of the present application (296 K). The CO2 adsorption capacity of SHU-1c is 24.5 cm 3 / g, and the CH4 adsorption capacity is only 5.9 cm 3 / g at 296 K and 100 kPa. The CO2 adsorption capacity is significantly higher than the CH4 adsorption capacity, and the ratio of the two is 4.2 Figure 4 ).

[0036] Figure 5 The multi-component gas breakthrough experiment diagram of the 9,9'-spirobifluorene-containing supermicroporous metal-organic framework material (SHU-1c) of the present application. When using CO2 / CH4 mixed gas (50 / 50, V / V), the CH4 breakthrough time in the SHU-1c material is 12.9 s / g, and the CO2 breakthrough time in the SHU-1c material is 118.1 s / g 3 at a flow rate of 4.00 cm Figure 5 / min. The CO2 / CH4 separation coefficient calculated by breakthrough experiment is 3.5, and the results show that SHU-1c has potential application value in the separation of CO2 / CH4 mixed gas.

[0037] Experimental test analysis:

[0038] I. Single crystal structure determination:

[0039] Carefully select suitable SHU-1c single crystals under an Olympus SZX-16 microscope, then wrap the single crystals with Paratone-N mineral oil, fix them with a crystal holder, and then transfer them to the goniometer head of the diffractometer for centering, and then start collecting diffraction data. The single crystal X-ray diffraction data of the material prepared in this embodiment 1 were collected by a Bruker / ARINAX MD2 diffractometer of Shanghai Synchrotron Radiation Facility BL17B1 beamline, and the detector was a MarCCD-300. The collection temperature was 100 K, the detector distance was 90 mm, and the diffraction wavelength was 0.7107 A. The exposure time was 0.5 s. The diffraction data were collected by ω scanning, the scanning range was 0-360°, and the swing angle was 1°. Absorption correction and data reduction were performed using HKL3000. Refinement was performed on SHELXTL using the least squares method. The final refinement parameters are SHU-1c: R1=0.0883, wR2=0.2290, S=1.068.

[0040] II. Activation, Surface Area, Gas Adsorption and Gas Separation:

[0041] A polycrystalline sample of the material prepared in Example 1 was soaked in anhydrous ethanol for 3 days, then the sample was transferred to a degassing line station of a Micromeritics physical adsorption instrument, and degassed under vacuum at 100°C for 24 hours; then the sample was transferred to a test line station for testing of gas adsorption properties, and about 300 mg of sample was used for the test. The gases used for the test included N2, CO2, C2H2 and CH4, all of which were of 5N purity. When performing a real-time dynamic multi-component gas breakthrough experiment, about 1.2 g of the polycrystalline sample was soaked in anhydrous ethanol for 3 days, then was filled into a breakthrough column (about 7.6 cm in length), and degassed under vacuum at 100°C for 4 hours, and the test was performed at a flow rate of 4.00 cm 3 / min using a CO2 / CH4 mixed gas (50 / 50, V / V).

[0042] Example 2

[0043] This example provides a preparation method of a 9,9'-spirobifluorene-containing super-microporous metal-organic framework material, and the specific steps refer to Example 1, and the only difference is that in step S1, 30 mg of raw material SHU-1 of chemical formula {[(CH3)2NH2]2[(Ca4O)L4(H2O)4]·6DMF} ∞ is weighed and added into a 1.5 mL Eppendorf centrifuge tube; 10 ml of deionized water is added into a 100 mL Schott Duran blue cap bottle, and a 10 mL glass sample bottle is placed in the bottle; the Eppendorf centrifuge tube containing SHU-1 is placed in the glass sample bottle with the opening exposed, and then the cap of the Schott Duran blue cap bottle is tightly screwed, and the bottle is left standing;

[0044] Finally, a 9,9'-spirobifluorene-containing super-microporous metal-organic framework material is prepared, which is recorded as SHU-1c; and the yield of SHU-1c is calculated to be 70%.

[0045] Example 3

[0046] This example provides a preparation method of a 9,9'-spirobifluorene-containing super-microporous metal-organic framework material, and the specific steps refer to Example 1, and the only difference is that in step S2, the operation of standing and grinding is repeated until the end of 1 week.

[0047] Finally, a 9,9'-spirobifluorene-containing super-microporous metal-organic framework material is prepared, which is recorded as SHU-1c; and the yield of SHU-1c is calculated to be 81%.

[0048] In summary, the present application uses SHU-1 as raw material, through the induction of water vapor, SHU-1 occurs structural transformation, and then form 9,9'-spirobifluorene containing supermicroporous metal-organic framework material (SHU-1c). The preparation method is simple, mild conditions, environment friendly, high yield. The 9,9'-spirobifluorene containing supermicroporous metal-organic framework material in the present application has a three-dimensional structure formed by the connection of helical chain and rigid ligand, the porosity is about 21%, has constant pore, BET specific surface area is 187m 2 / g, pore volume is 0.14cm 3 / g, has potential application prospect in CO2 gas adsorption and CO2 / CH4 mixed gas separation.

[0049] The above describes the embodiments of the present application in combination with the drawings, but the present application is not limited to the above embodiments, and can be changed in many ways according to the purpose of the present application, any change, modification, replacement, combination or simplification made according to the spirit and principle of the present application should be equivalent replacement, as long as it meets the purpose of the present application, as long as it does not deviate from the technical principles and inventive concept of the present application, it belongs to the protection scope of the present application.

Claims

1. A microporous metal-organic framework material containing 9,9'-spirodifluorene, characterized in that, The ultramicroporous metal-organic framework material containing 9,9'-spirodifluorene has a three-dimensional structure composed of helical chains containing calcium-oxygen polyhedra and rigid spirodifluorene ligands, and its chemical formula is {[Ca6L6(DMF)2(H2O)8}. 2DMF 3H2O} ∞ Where L represents an organic ligand and DMF represents N,N-dimethylformamide; The organic ligand L is 9,9'-spirodifluorene-2,2'-dicarboxylic acid, with the following structural formula: ； The ultramicroporous metal-organic framework material containing 9,9'-spirodifluorene crystals is crystallized in a monoclinic crystal system. C 2 / c The space group, composed of pentagonal bipyramidal calcium-oxygen polyhedra, forms two oriented one-dimensional helical chains interconnected by sharing edges. An aromatic ring of 9,9'-spirodifluorene-2,2'-dicarboxylic acid separates the two helical chains, with CH atoms existing between the aromatic rings. π Through interaction, helical chains and rigid ligands connect to form a three-dimensional structure; 9,9'-spirodifluorene-2,2'-dicarboxylic acid and one-dimensional helical chains form one-dimensional channels.

2. The ultramicroporous metal-organic framework material containing 9,9'-spirodifluorene according to claim 1, characterized in that, The opening size of the one-dimensional channel is 5.4 × 3.9 Å, which is classified as an ultramicropore.

3. The ultramicroporous metal-organic framework material containing 9,9'-spirodifluorene according to claim 1, characterized in that, The ultraporous metal-organic framework material containing 9,9'-spirodifluorene is applied to CO2 gas adsorption and CO2 / CH4 mixed gas separation.

4. A method for preparing an ultramicroporous metal-organic framework material containing 9,9'-spirodifluorene as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Weigh out 30-58 mg of the chemical formula {[(CH3)2NH2]2[(Ca4O)L4(H2O)4]·6DMF} ∞ Add the raw material SHU-1 to a 1.5 mL Aisjin plastic centrifuge tube; Add 10-20 mL of deionized water to a 100 mL Schott Duran blue cap bottle and place a 10 mL glass sample bottle inside. Place an open SHU-1 plastic centrifuge tube into the glass sample bottle, then tighten the cap of the Schott Duran blue cap bottle and let it stand. S2. During the settling process, every 1 to 2 days, remove the centrifuge tube containing the raw material SHU-1, grind the raw material, and then put it back into the Schott-Duran blue-capped bottle for continued settling. Repeat the settling-grinding operation until 1 to 2 weeks have passed. Remove the sample from the centrifuge tube and air dry it to obtain the ultramicroporous metal-organic framework material containing 9,9'-spirodifluorene, denoted as SHU-1c.

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