Zirconium-based metal organic framework material as well as preparation method and application thereof

Abstract

The invention discloses a zirconium-based metal organic framework material with high dehumidification capacity and excellent cycling stability and containing a one-dimensional pore channel as well as a preparation method and application of the zirconium-based metal organic framework material. By horizontally and axially expanding a core part of an X-type organic connector, an ortho-dibenzoic acid part of the organic connector is kept unchanged; the isomorphic synthesis of the zirconium-based metal organic framework material can simultaneously meet three necessary conditions that the zirconium-based metal organic framework material contains a one-dimensional pore channel, Zr6-cluster chelating coordination formate radicals are coplanar and the oxygen spacing of adjacent Zr6-cluster formic acid is less than or equal to 5.4. Meanwhile, introduction of water molecules in the center position between the adjacent Zr6 clusters can be effectively limited under the three conditions, and therefore the situation that the whole grid structure collapses due to unbalanced stress caused by the water molecules in the position in the desorption process is prevented. By intentionally shortening or prolonging the length of the organic linker core in the horizontal axial direction, the synthesized zirconium-based metal organic framework material containing the one-dimensional pore channel shows high water adsorption cycle stability.

Description

Technical Field

[0001] The present invention relates to a zirconium-based metal-organic framework material, a preparation method thereof and an application thereof, and belongs to the technical field of water adsorption materials. Background Art

[0002] Metal-organic frameworks (MOFs) with high hydrolytic stability are regarded as potential candidate materials for water adsorption applications (such as drying, atmospheric water collection, heat pumps and humidity control). Among them, zirconium-based metal-organic frameworks (Zr-MOFs) with excellent chemical stability have attracted wide attention. However, in terms of water vapor adsorption, in addition to hydrolytic stability, the candidate MOF materials should also have a strong ability to resist the capillary force caused by water desorption, which is closely related to the mechanical stability of the MOF. Although many Zr-MOFs with high water stability have been reported so far, materials that can resist capillary force and maintain mechanical stability are still scarce. In most of these limited cases, the focus is on revealing the uniqueness and excellent performance of the candidate materials, but there is still a lack of systematic research on the relationship between structural design and water adsorption mechanical stability. There is currently no effective guiding principle for the bottom-up structural design of MOFs with high mechanical stability for water adsorption.

[0003] Previously, based on a typical Zr-MOF (NU-1000) with one-dimensional mesoporous channels, we reported a new example of organic linker isomerization, that is, moving the terminal benzoate rings on the 1, 3, 6, 8 positions of pyrene to the 4, 5, 9, 10 positions, generating c a NU-1000 isomer with blocked pores, which exhibits one of the highest water adsorption capacities and significantly improved cycling stability. We speculated that the improvement of cycling stability is due to c the chelating formate in the pore region hinders its hydrolysis through steric hindrance, thus stabilizing the nodes and preventing them from being distorted by capillary force. However, whether this pore-blocking c strategy is limited to specific structures or widely applicable to other structure types is still unknown.

[0004] Inspired by this pore-blocking c strategy, in this application, a bottom-up method is first described, by selectively constructing zirconium-based MOFs with one-dimensional channels while restricting Zr 6The accessibility of nodes to water along the pore direction is used to construct zirconium-based MOFs with high water vapor cycling stability. All Zr-MOFs constructed by this method exhibit excellent water vapor cycling stability. In addition, a novel Zr-MOF (NJTech-5) synthesized through a further organic linker design strategy shows one of the highest water adsorption capacities, making it one of the excellent candidate materials in the field of humidity control based on water adsorption. Summary of the Invention

[0005] The object of the present invention is to provide a zirconium-based metal-organic framework material, its preparation method and application. An organic linker configuration design strategy is adopted, that is, by horizontally axially expanding the core part of the X-type organic linker, ensuring that the "ortho-dibenzoic acid" part of the organic linker remains unchanged, so as to simultaneously meet the requirements of containing one-dimensional pores, Zr 6 cluster chelating coordination formate coplanar and adjacent Zr 6 cluster formate oxygen spacing ≤ 5.4 Å for the isomorphic synthesis of zirconium-based metal-organic framework materials. Simultaneously meeting the above three conditions can effectively limit the introduction of water molecules at the central position between adjacent Zr 6 clusters, thereby preventing the uneven force caused by the water molecules at this position during the desorption process from leading to the collapse of the overall grid structure. By intentionally shortening or lengthening the length of the organic linker core in the horizontal axis direction, the synthesized zirconium-based metal-organic framework materials containing one-dimensional pores all exhibit high water adsorption cycling stability.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: A zirconium-based metal-organic framework material, in which each Zr 6 cluster node is coordinatively connected with 12 X-type organic linkers 4,4',4'',4'''-(pyrazino[2,3-g]quinoxaline-2,3,7,8-tetrayl)tetrabenzoic acid (H 4 PyQ) with 4-connectivity, and each X-type organic linker H 4 PyQ is coordinatively connected with four Zr 6 clusters with 12-connectivity; among them, Zr 6 cluster nodes are linearly arranged along the one-dimensional pore, having coplanar chelating coordination formate; the distance between formate oxygens of adjacent Zr 6 clusters along the pore direction is ≤ 5.4 Å.

[0007] The preparation method of the above zirconium-based metal-organic framework material is to dissolve H 4 PyQ, zirconium tetrachloride and a template agent in DMF, heat once, wash, and then disperse in a mixed solution of DMF and an acid solution, and then heat twice to remove the template agent, centrifuge, wash, replace with a low-boiling solvent, dry, and activate.

[0008] Preferably, the template agent is propionic acid; and the addition ratios of zirconium tetrachloride, H 4 PyQ, and propionic acid are (5 - 10) mg : (8 - 12) mg : (1 - 5) mL.

[0009] Preferably, the conditions for the first heating are: 100 - 140 °C, 15 - 20 hours; The conditions for the second heating are: 100 - 140 °C, 15 - 20 hours; The conditions for drying are: under non - vacuum conditions, 50 - 75 °C, 1 - 2 hours; The conditions for activation are: under vacuum conditions, 80 - 140 °C, 10 - 15 hours.

[0010] Preferably, the washing is carried out with an organic solvent, and acetone is used for the replacement of the low - boiling solvent.

[0011] The application of the above - mentioned zirconium - based metal - organic framework material in water vapor adsorption and desorption.

[0012] A zirconium - based metal - organic framework material with one - dimensional pores, the material contains one - dimensional pores, and Zr 6 cluster chelates and coordinates formate ions on the same plane, and at the same time, the formate oxygen distance between adjacent Zr 6 clusters is ≤ 5.4 Å.

[0013] Preferably, the topological structure of the zirconium - based metal - organic framework material is bct type, csq type, scu type, shp type, etc.

[0014] Preferably, the combination of pores can generate kgm , sql , kgd and bex and other cross - sections; The ligand in the zirconium - based metal - organic framework material is H 2 TCPP, H 4 TCPB - Br 2 , H 4 MDIP, fumaric acid, H 4 TPTA, H 6 PET, H 4 ETTC, H 4 TTFTB, H 4 TCPE, H 4 PyQ, one or several of them.

[0015] A method for improving the water adsorption cycle stability of zirconium-based metal-organic framework materials is to make the organic linker have an "ortho-dibenzoic acid" unit and extend the length of the organic linker axially along the symmetry axis of the "ortho-dibenzoic acid" unit when preparing the metal-organic framework materials.

[0016] The beneficial effects of the present invention are as follows: The present invention proposes a configuration design strategy for organic linkers, that is, by horizontally axially expanding the core part of the X-type organic linker to ensure that the "ortho-dibenzoic acid" component of the organic linker remains unchanged, so as to simultaneously meet the requirements of having one-dimensional pores, Zr 6 cluster chelating coordination formate coplanar and adjacent Zr 6 cluster formate oxygen spacing ≤ 5.4 Å, and the isomorphic synthesis of zirconium-based metal-organic framework materials that meet the three necessary conditions. By intentionally shortening or lengthening the length of the core of the organic linker in the horizontal axis direction, the synthesized zirconium-based metal-organic framework materials with one-dimensional pores all show high water adsorption cycle stability. Among them, NJTech-5, as a new type shp zirconium-based metal-organic framework with a topological structure, has high water absorption capacity and is one of the ideal candidate materials in the field of humidity control. Description of the Drawings

[0017] Figure 1 Schematic diagram of the pore force situation of Zr-MOFs with one-dimensional pores during water molecule desorption. a) On the plane of each pore cross-section of one-dimensional pore Zr-MOFs, when the second coordination layer water molecules (from the water clusters outside the coordinated water molecules) desorb, the force borne by each Zr 6 node is symmetric; b) Three typical pore shapes contained in Zr-MOFs with one-dimensional pores; c) Unbalanced force caused by water molecules in the adjacent Zr 6 coordination plane; d) to h) show Zr-MOFs with one-dimensional pores, along the pore direction Zr 6 cluster chelating coordination formate coplanar, and the schematic diagram of the minimum space required for the possible coordination modes of adjacent Zr 6 nodes; Figure 2 Unit structure diagrams of four pairs of Zr-MOFs; Figure 3 Inherited "Zr 6 cluster chelating coordination formate coplanar and adjacent Zr 6 cluster formate oxygen spacing less than 5 Å" feature Zr-MOFs list, the pore cross-section patterns of these Zr-MOFs can be roughly divided into three categories: 1) Cross-section has sql type grid of MIP-203, PCN-206, and NU-913; 2) Cross-section has kgdNU-1600 with a type of grid; 3) The cross-section has bex Zr-PEP-1 with a type of grid; Figure 4 The dimensional changes of the organic linker used to construct Zr-MOFs with one-dimensional pores in different dimensions affect the distance between adjacent coplanar Zr 6 nodes. a) The prototype organic linker can control the Zr 6 node distance to be 3 - 5 Å; b) Based on the prototype organic linker, the core part is laterally extended, and the Zr 6 node distance can still be controlled to be 3 - 5 Å; c) Based on the prototype organic linker, the core part is longitudinally extended, and the Zr 6 node distance will increase significantly to >10 Å; d) Based on the prototype organic linker, the end arms are extended, and the Zr 6 node distance will increase significantly to >10 Å; e) Based on the prototype organic linker, the arm angle is changed, and the Zr 6 node distance will increase to >5.4 Å; Figure 5 For a) laterally contracting or extending the H 4 The core part of HTPTA can generate H 4 TCPE and H 4 PyQ respectively; b) The PXRD pattern of NJTech-5; c) The schematic diagram of the crystal structure of NJTech-5, and the size of the one-dimensional triangular pores is about 1.2 nm; d) The distance between the formate oxygen of adjacent coplanar Zr 6 clusters along the one-dimensional triangular pores of NJTech-5 is 3.9 Å; e) The nitrogen adsorption isotherm of Zr-TCPE before and after the water vapor adsorption cycle; f) The five-time water vapor adsorption isotherm of Zr-TCPE; g) The nitrogen adsorption isotherm of NJTech-5 before and after the water vapor adsorption cycle; h) The five-time water vapor adsorption isotherm of NJTech-5; i) The dehumidification working ability ranking of NJTech-5 between 40% - 60% relative humidity; e) The 20-time kinetic water vapor adsorption cycle test of NJTech-5. Detailed implementation mode

[0018] Zirconium-based metal-organic framework materials (Zr-MOFs) show great potential in many water adsorption-related applications due to their excellent hydrolysis stability. However, hydrolysis stability is not always a reliable guarantee for the long-term service of zirconium-based metal-organic framework materials in water adsorption. This application reveals a method of restricting the hexanuclear zirconium cluster nodes (Zr 6The mechanism of water molecule accessibility in zirconium-based metal-organic framework materials. According to this mechanism, through specific topologies (such as csq type, scu type, shp type, etc.), the unsaturated coordination sites occupied by chelated formate on the hexanuclear zirconium cluster nodes are controlled on the same plane and maintained at an appropriate distance (≤5.4 Å), which can effectively prevent the introduction of water molecules in this plane and avoid the structural collapse caused by uneven stress when water vapor desorbs due to the departure of water molecules in the plane, thus significantly improving the cyclic stability of zirconium-based metal-organic framework materials in water adsorption. Based on this mechanism, this application proposes a strategy for the design of organic linker configurations, that is, by horizontally axially expanding the core part of the X-type organic linker to ensure that the "ortho-dibenzoic acid" component of the organic linker remains unchanged, to achieve the isomorphic synthesis of zirconium-based metal-organic framework materials that can simultaneously meet the three necessary conditions of containing one-dimensional pores, the chelating coordination of Zr 6 clusters with formate on the same plane and the formate oxygen distance between adjacent Zr 6 clusters ≤5.4 Å. By intentionally shortening or lengthening the length of the organic linker core in the horizontal axis, the synthesized zirconium-based metal-organic framework materials containing one-dimensional pores all exhibit high cyclic stability in water adsorption. Among them, NJTech-5, as a new shp topological structure of zirconium-based metal-organic framework, has high water absorption capacity and is one of the ideal candidate materials in the field of humidity control.

[0019] Synthesis of pure-phase zirconium metal-organic framework material Zr-MOFs.

[0020] Synthesis of PCN-224: Dissolve 120 mg of zirconium oxychloride octahydrate (ZrOCl 2 ·8H 2 O, 0.67 mmol), 40 mg of meso-tetrakis(4-carboxyphenyl)porphine (H 2 TCPP, 0.052 mmol) and 1.6 g of benzoic acid in 8 mL of N,N-dimethylformamide (DMF), and ultrasonically treat for 10 minutes. Place the obtained mixture in a Teflon reactor and heat at 120 °C for 24 hours. Wash this product thoroughly three times with DMF, and then disperse it in a solution of 12 mL of DMF and 0.5 mL of 8 M hydrochloric acid aqueous solution. Heat the mixture in an oven at 100 °C for 18 hours. After cooling to room temperature, collect the solid by centrifugation, wash it three times with DMF and acetone respectively, and then vacuum dry at 65 °C. Finally, vacuum dry at 150 °C for 8 hours to obtain the activated sample of PCN-224.

[0021] Synthesis of PCN-222: Dissolve 10 mg of meso-tetrakis(4-carboxyphenyl)porphine (H 2TCPP (0.013 mmol) and 7 mg of zirconium tetrachloride (ZrCl 4 , 0.03 mmol) were added to a vial containing 10 mL of DMF and dissolved under ultrasonic assistance. Then, 2.82 mL of formic acid (76 mmol) was added to the vial, and further ultrasonic treatment was performed to obtain a homogeneous reaction mixture. The vial was placed in an oven at 120 °C for 16 hours and then cooled to room temperature. The white product was collected by centrifugation and washed three times with DMF and acetone respectively, and then dried under vacuum at 65 °C. Finally, it was dried under vacuum at 120 °C for 16 hours to obtain an activated sample of PCN-222.

[0022] Synthesis of NU-1008: Zirconium oxynitrate hexahydrate (0.267 mmol, 66.4 mg), N,N-dimethylformamide (1.5 mL), and formic acid (1 mL) were added to a vial. The mixture was dissolved by ultrasonic treatment and heated at 80 °C for 1 hour to obtain a Zr 6 node solution. Meanwhile, 1,4-dibromo-2,3,5,6-tetrakis(4-carboxyphenyl)benzene (H 4 TCPB-Br 2 , 0.0533 mmol, 38.2 mg) and N,N-dimethylformamide (1.5 mL) were added to a vial and heated at 80 °C for 1 hour to dissolve the organic linker. After cooling to room temperature, the clear mixture containing H 4 TCPB-Br 2 linker was added to the prepared Zr 6 cluster solution. The mixture was sealed and heated at 100 °C overnight (15 - 16 hours). After cooling to room temperature, the resulting powder was collected by centrifugation and washed with N,N-dimethylformamide (5 mL × 3) and acetone (5 mL × 3). The powder was soaked in acetone overnight and washed three more times with acetone. Finally, it was dried under vacuum at 100 °C for 12 hours to obtain an activated sample of NU-1008.

[0023] Synthesis of MIP-201: Zirconium sulfate (Zr(SO 4 ) 2 ·4H 2 O, 108 mg) and 5-[(3,5-dicarboxyphenyl)methyl]benzene-1,3-dicarboxylic acid (H 4The MDIP (51 mg) was transferred to a 50 mL round-bottom flask, and then water (3 mL) and acetic acid (1 mL) were added under stirring at room temperature. The reaction was refluxed at 120 °C for 12 hours and then cooled to room temperature. The obtained solid product was collected by filtration, washed with ethanol, and air-dried. A pale golden crude product was obtained. Finally, it was dried under vacuum at 120 °C for 12 hours to obtain an activated sample of MIP-201.

[0024] Synthesis of MIP-203: 466 mg (2 mmol) of zirconium tetrachloride was added to a solution containing 116 mg (1 mmol) of fumaric acid and 5 mL of pure formic acid. After sonication for 10 minutes, the reaction was heated in an oven at 120 °C for 72 hours. After the reaction was cooled to room temperature, the white product was collected by filtration, washed with water and ethanol, then subjected to six solvent exchanges with ethanol (8 hours each time), and activated at 100 °C under high vacuum for 24 hours before measurement.

[0025] Synthesis of PCN-206: 20 mg (0.086 mmol) of zirconium tetrachloride, 10 mg (0.036 mmol) of 4,4',4",4"'-(pyrazine-2,3,5,6-tetraalkyl)tetrabenzoic acid (H 4 TPTA) and 268.6 mg of benzoic acid were added to 6 mL of N,N-dimethylformamide (DMF). The mixture was heated in an oven at 120 °C for 24 hours and then cooled to room temperature. This white product was washed thoroughly with DMF three times and then dispersed in a solution of 3 mL of DMF and 0.125 mL of 8 M hydrochloric acid aqueous solution. The mixture was heated in an oven at 100 °C for 18 hours. After cooling to room temperature, the solid was collected by centrifugation and washed three times with DMF and acetone respectively, and then dried under vacuum at 65 °C. Finally, it was dried under vacuum at 120 °C for 16 hours to obtain an activated sample of PCN-206.

[0026] Synthesis of NU-1600: 60 mg (0.186 mmol) of zirconium chloride octahydrate, 30 mg (0.031 mmol) of 4,4',4'',4''',4''',4'''''-(9,10-dihydro-9,10-[1,2]benzanthracene-2,3,6,7,14,15-hexyl)hexabenzoic acid (H 6 PET) and 4 mL of formic acid were added to 4 mL of N,N-dimethylformamide (DMF). The mixture was sealed and heated to 120 °C and maintained for 18 hours, and then cooled to room temperature. The white product was collected by centrifugation and washed three times with DMF and acetone respectively, and then dried under vacuum at 65 °C. Finally, it was dried under vacuum at 120 °C for 16 hours to obtain an activated sample of NU-1600.

[0027] Synthesis of WSU-5: In a 4 mL glass bottle, 30 mg (0.13 mmol) of zirconium tetrachloride and 5 mg (0.018 mmol) of tetrakis[4-(4'-carboxyphenyl)phenyl]ethylene (H 4 ETTC) were dissolved in 2 mL of N,N-dimethylformamide (DMF). 1 mL of formic acid was added, the bottle cap was covered, and it was placed in an oven at 135 °C and heated for 6 hours. After the reaction was completed, the glass bottle was taken out of the oven to obtain the synthesized WSU-5 (4.3 mg, yield based on zirconium tetrachloride was 8.2%). The synthesized WSU-5 was cooled, washed three times with fresh DMF, and then soaked in fresh DMF for 24 hours. Then the MOF was washed three times with acetone and soaked in fresh acetone overnight to obtain the washed sample. Finally, it was dried under vacuum at 25 °C for 12 hours to obtain the activated sample of WSU-5.

[0028] Synthesis of Zr-TTF: 40 mg (0.172 mmol) of zirconium tetrachloride, 40 mg (0.06 mmol) of tetrathiafulvalene-3,4,5,6-tetra(4-benzoic acid) (H 4 TTFTB) and 2.8 mL of acetic acid were added to 8 mL of N,N-dimethylformamide (DMF). The mixture was sealed and heated to 120 °C and maintained for 12 hours, and then cooled to room temperature at a rate of 5 °C / h. This red product was washed thoroughly three times with DMF, and then dispersed in a solution of 12 mL of DMF and 0.5 mL of 8 M hydrochloric acid aqueous solution. The mixture was heated in an oven at 100 °C for 18 hours. After cooling to room temperature, the solid was collected by centrifugation and washed three times with DMF and acetone respectively, and then dried under vacuum at 65 °C. Finally, it was dried under vacuum at 120 °C for 16 hours to obtain the activated sample of Zr-TTF.

[0029] Synthesis of Zr-TCPE: In a 7 mL glass bottle, 10 mg (0.043 mmol) of zirconium tetrachloride and 120 μL of acetic acid were dissolved in 2 mL of N,N-dimethylformamide (DMF). The glass bottle was heated at 100 °C for 1 hour. After cooling to room temperature, 20 μL of water, 160 μL of acetic acid and 10 mg (0.02 mmol) of 1,1,2,2-tetrakis(4-carboxyphenyl)ethylene (H 4TCPE). After ultrasonic treatment, the glass bottle was heated at 120 °C for 24 hours and then cooled to room temperature. The white product was washed thoroughly with DMF three times and then dispersed in a solution of 3 mL DMF and 0.125 mL 8 M hydrochloric acid aqueous solution. The mixture was heated in an oven at 100 °C for 18 hours. After cooling to room temperature, the solid was collected by centrifugation and washed three times with DMF and acetone respectively, and then dried in vacuo at 65 °C. Finally, it was dried in vacuo at 120 °C for 16 hours to obtain an activated sample of Zr-TCPE.

[0030] Synthesis of NJTech-5: In a 20 mL glass bottle, 8.4 mg (0.036 mmol) of zirconium tetrachloride and 10 mg (0.015 mmol) of 4,4',4'',4'''-(pyrazino[2,3-g]quinoxaline-2,3,7,8-tetrayl)tetrabenzoic acid (H 4 PyQ) were added to 10 mL of N,N-dimethylformamide (DMF) and dissolved under ultrasonic assistance. Then 2 mL of propionic acid was added to the glass bottle and further ultrasonicated to obtain a homogeneous reaction mixture. The glass bottle was placed in an oven at 120 °C and heated for 16 hours, and then cooled to room temperature. The yellow product was washed thoroughly with DMF three times and then dispersed in a solution of 3 mL DMF and 0.125 mL 8 M hydrochloric acid aqueous solution. The mixture was heated in an oven at 100 °C for 18 hours. After cooling to room temperature, the solid was collected by centrifugation and washed three times with DMF and acetone respectively, and then dried in vacuo at 65 °C. Finally, it was dried in vacuo at 120 °C for 16 hours to obtain an activated sample of NJTech-5.

[0031] Synthesis of CAU-24: 1,2,4,5-Tetrakis(4-carboxyphenyl)benzene (H 4 TCPB, 29.8 mg, 53.3 μmol) was added to a glass reactor. Subsequently, N,N-dimethylformamide (DMF, 1.5 mL) and formic acid (99%, HCOOH, 1030 μL, 27.3 mmol) were added, and then an aqueous solution of zirconium(IV) dinitrate oxide hydrate (500 μL, 0.5333 M) was added. The glass reactor was sealed and heated to 100 °C with stirring using an aluminum heating block for 15 minutes. The colorless precipitate was centrifuged in the mother liquor, and then the mother liquor was poured out. After the precipitate was redispersed, it was centrifuged twice with DMF (2 mL). To remove DMF from the product, it was washed and centrifuged four times with acetone (2 mL). The obtained white solid was dried in air at 70 °C and activated at 120 °C under high vacuum for 24 hours before measurement.

[0032] Synthesis of MOF-FF: The synthesized MOF (40 mg, 0.0182 mmol) was suspended in 15 mL of dimethyl sulfoxide (DMSO) for solvent exchange for 5 hours. 8 M aqueous hydrochloric acid (0.6 mL) was added to the MOF solution and left overnight at room temperature. The yellow powder was separated by centrifugation, washed four times with DMSO, and then solvent-exchanged with ethanol, using 10 mL of ethanol each time, for a total of four times for 12 hours. 2 equivalents (5.6 µL, 0.04 mmol) of triethylamine (TEA) was added to 10 mL of the mixture and left overnight at room temperature. The TEA treatment was repeated to completely remove the Cl⁻ anions. The resulting powder was separated by centrifugation and washed three times with 10 mL of ethanol and acetone respectively. The final product was separated by centrifugation and dried in a vacuum oven at 80 °C for 1 hour.

[0033] Four pairs of Zr-MOFs were selected in this application, and the MOFs in each pair were composed of the same building units (as Figure 2 shown). For the pair of PCN-224 and PCN-222, they were both constructed from H 4 TCPP and Zr 6 nodes (as Figure 2 shown in a). Due to the different connection modes of the Zr 6 nodes, they exhibited completely different topological structures. Among them, PCN-224 had 6-connected Zr 6 nodes and was a she type network ( Figure 2 b), while PCN-222 had 8-connected Zr 6 nodes and was a csq type network ( Figure 2 c). Due to their instability to capillary forces, they were not suitable as candidate materials for water vapor adsorption.

[0034] In contrast, the pair of NU-600 ( 4 type topological structure, 6 e) and NU-1008 ( she type topological structure, Figure 2 e) constructed from H csq type topological structure, Figure 2 f) showed completely different water vapor cycle stabilities. The saturated adsorption capacity of NU-600 decreased by 55% in the third cycle, indicating its instability to capillary forces. In contrast, NU-1008 was more stable.

[0035] In another pair of NU-601 and ISO-NU-1000, the same difference in cycle stability was also observed. NU-601 with a she type network ( Figure 2h) 80% of the initial saturated adsorption capacity was lost in the second cycle. However, ISO-NU-1000 ( Figure 2 i) was tested to be extremely stable even after 20 water adsorption cycles. Another pair, MIP-200 ( Figure 2 k) and MIP-201 ( Figure 2 l) also provided the same information, showing the vulnerability of MIP-201 to capillary forces and the stability of MIP-200 in water vapor adsorption.

[0036] Except for the first pair of Zr-MOFs, the other pairs tend to illustrate that the possibility of constructing Zr-MOFs with high water cycle stability depends on the cross-sectional structure of the pores (the cross-section of the stable triangular-hexagonal combined pores kgm and the unstable square pores sql cross-section). However, PCN-222 in the first pair negates this possibility. Comparing PCN-222 with NU-1008, ISO-NU-1000, and MIP-200, they all have the same structural characteristics, namely one-dimensional pores with a triangular-hexagonal combined pore cross-section, Zr 6 cluster chelating coordinated formate coplanar and adjacent Zr 6 cluster formate oxygen spacing ≤ 5 Å. For NU-1008, ISO-NU-1000, and MIP-200, the distance between adjacent Zr 6 nodes in the pore direction is limited within 5 Å. When the formate ligand chelates and occupies the node, it will hinder water molecules from accessing the node. In contrast, their isostructural counterparts, such as NU-600, NU-601, and MIP-201, due to topological changes, their adjacent Zr 6 nodes chelating coordinated formate are not coplanar, thus improving the accessibility of water molecules and leading to unsatisfactory water cycle stability.

[0037] Given that the above three stable Zr-MOFs have similar structural characteristics, this application explores whether this feature can be further extended to other Zr-MOFs besides those with kgm cross-sectional grids (regarded as having mechanical stability) csq type networks. From all the Zr-MOFs reported so far, several cases that inherit the feature of "Zr 6 cluster chelating coordinated formate coplanar and adjacent Zr 6 cluster formate oxygen spacing less than 5 Å" were selected. In addition, these Zr-MOFs also have two other features: 1) containing one-dimensional pores; 2) the pore cross-section contains a rhombic grid regarded as mechanically unstable.

[0038] According to the pore cross-sectional patterns of these Zr-MOFs, they can be roughly divided into three categories: 1) MIP-203, PCN-206, and NU-913 with sql -type grids in the cross-section; 2) NU-1600 with kgd -type grids in the cross-section; 3) Zr-PEP-1 with bex -type grids in the cross-section. sql MIP-203 is formed by connecting fumaric acid and Zr kgd clusters, presenting a bex network with 10-connected Zr

[0039] nodes. Due to the short distance (~2.2 Å) between adjacent coplanar Zr 6 nodes along the pore direction, each pair of adjacent Zr 6 nodes is bridged by two formate ligands, preventing water molecules from entering the central position between the nodes. The water adsorption cycle stability of MIP-203 was further tested, and the results showed that its initial saturated adsorption capacity could reach 0.18 g g bct -1, but in the second cycle, its saturated adsorption capacity decreased to 0.14 g g 6 -1. There was no further decrease in subsequent cycles. The decrease between the first and second cycles was due to incomplete removal of water molecules. Reactivating the sample at 120 °C for 12 hours could completely restore the porosity of MIP-203, indicating that its structure remained stable after multiple water adsorption cycles. 6 -1. -1 -1 -1 -1.

[0040] PCN-206 is formed by connecting the linker TPTA 4- and Zr 6 clusters, presenting a scu network. The one-dimensional pores in it have a cross-section with a sql grid, and the distance between each pair of adjacent coplanar Zr 6 nodes along the pore direction is 3.4 Å. PCN-206 exhibits a water adsorption capacity as high as 0.61 g g -1 -1, and there is almost no decrease in the adsorption capacity during subsequent cyclic adsorption tests.

[0041] NU-913 composed of the relatively flexible linker BPCP 4- has the same topological structure as PCN-206. Due to the configuration of the organic linker, the one-dimensional pores in NU-913 are more square-like than rhombic. However, the distance between adjacent coplanar Zr 6 nodes along the pore direction is still limited within 4.3 Å. After connecting trifluoroacetate groups at the unsaturated sites, NU-913 shows high water adsorption cycle stability similar to that of PCN-206.

[0042] These three Zr-MOFs with sql cross-sections indicate that the mechanically unstable rhombic shape on the pore cross-section has little negative impact on the water cycle stability of these Zr-MOFs. The rearrangement of the rhombuses can also form kgd type grids, and NU-1600 is one of the Zr-MOFs with this cross-sectional grid.

[0043] NU-1600 is composed of PET-1 6- linkers and Zr 6 clusters, showing typical one-dimensional pores with a pore size of 7.4 Å. The distance between every pair of adjacent coplanar Zr 6 nodes along the pore direction is 4.5 Å. Within this range, water molecules cannot enter the nodes along the pore direction. Therefore, the water adsorption isotherms of NU-1600 in multiple cycles were further measured. NU-1600 showed a water vapor saturation adsorption capacity of up to 0.84 g g -1 in the initial cycle and still maintained 95% of its capacity in the fifth cycle, indicating its strong ability to resist capillary force.

[0044] For Zr-PEP-1 assembled from the octahedral steric organic linker PEP-1 8- and Zr 6 clusters, its pore cross-section is a bex grid containing a rhombic grid. The distance between every pair of adjacent coplanar Zr 6 nodes along the one-dimensional pore direction is 4.2 Å. Zr-PEP-1 shows high water cycle stability and, combined with its high saturation adsorption capacity, is a good candidate for collecting water from the air.

[0045] From all the above cases with high water cycle stability, their one-dimensional pores have a high degree of structural similarity, that is, they contain one-dimensional pores, Zr 6 clusters chelated and coordinated with formate ions in the same plane and the formate oxygen distance between adjacent Zr 6 clusters is less than 5 Å. This is fundamentally attributed to the node structure and arrangement. The one-dimensional pore cross-sections in the above Zr-MOFs with high water cycle stability can be divided into three types: hexagonal, triangular, and rhombic, as shown in Figure 1 region b. The combination of these pores can produce kgm , sql , kgd and bex and other cross-sections. On the plane of each cross-section, when the second-shell water molecules (from the water clusters outside the coordinated water molecules) desorb, the force borne by each Zr 6 node is symmetric (as shown in Figure 1as shown in region a). During the desorption process, the capillary force caused by the water clusters in these Zr-MOFs with one-dimensional pores basically points to the center of the pores, as shown in Figure 1 region a). Therefore, within the range of each cross-section, the tensile force caused by such water molecules acting on each zirconium cluster is balanced. However, along the pore direction, the distances between adjacent coplanar Zr 6 nodes are different, which determines the cyclic stability of the target Zr-MOFs. When the distance is long enough, water molecules enter the exact center of the plane of adjacent coplanar Zr 6 nodes. Since the capillary force caused by the desorption of water clusters points to the center of the pores, the desorption process often leads to two modes of unbalanced forces as shown in Figure 1 region c), which depends on the specific topological structure of each Zr-MOF. This unbalanced tensile force is the decisive factor leading to the collapse of the entire structure. When the distance is narrow enough to block water molecules from entering the coplanar region, the water molecules can be symmetrically distributed above and below the plane, thus avoiding this unbalanced tensile force.

[0046] In Figure 1 regions d - h, several possible situations are shown, which respectively show the minimum space required for each coordination mode. In most cases, for Zr-MOFs, when the synthesis solvent is DMF (or DEF), the unsaturated coordination sites of Zr 6 nodes are mainly occupied by formate ions in a chelating manner (as shown in the single-crystal structures of NU-1000 and NU-1008). If the unsaturated sites on both sides of adjacent Zr 6 nodes are chelated by formate ions, considering the van der Waals radius, the distance between the coordinated oxygen atoms in the first coordination layer needs to be at least 5.2 Å (as shown in Figure 1 region f). The distance required to accommodate one chelating formate ion and one coplanar water molecule in the second coordination layer needs to be at least 5.4 Å (as shown in Figure 1 region g). If the bidentate chelating formate ligand is maintained, adding a coplanar water molecule in the second coordination layer in the middle requires at least 7.0 Å (as shown in Figure 1 region h). From the perspective of blocking water molecules from entering between adjacent Zr 6 nodes, a distance less than 5.4 Å is a safety guarantee. When the distance is less than 5.2 Å, it will not be sufficient to accommodate two chelating formate ions. Therefore, the most likely coordination node environment is the combination of a single chelating formate ion and a pair of coordinated hydroxyl-water (as shown in Figure 1 region e). This mode can also avoid the introduction of coplanar water molecules, thus contributing to improving the water cycle stability. In this application, for all Zr-MOFs with high water adsorption cycle stability, the coplanar Zr along the pore direction 6The distances between the cluster-coordinated oxygen atoms are all within the range of less than 5.4 Å, while the unstable PCN-222 (with a distance of 9.2 Å) is significantly beyond this range. When the distance is further shortened to 2.3 Å, MIP-203 exhibits a bridging formate pattern (as shown in the d region of Figure 1 ). This coordination pattern can also block the interference of coplanar water molecules, thus endowing MIP-203 with high water cycle stability. Since the synthesis conditions of these Zr-MOFs with high water adsorption cycle stability contain solvents such as DMF that are easily decomposed into formate, it is difficult to obtain products without coordinated formate during the synthesis stage. However, Zr-MOFs with clean nodes (without coordinated formate) obtained by the reported methods for removing coordinated formate instead show extremely poor water adsorption cycle stability (such as ISO-NU-1000-FF, CAU-24-FF, and MIP-203-FF), which verifies the conclusion that coordinated formate within the appropriate Zr 6 distance range hinders the introduction of coplanar water molecules to improve the water adsorption cycle stability of Zr-MOFs.

[0047] Based on the distance between coplanar Zr 6 nodes along the pore direction, it plays a crucial role in the water adsorption cycle stability of Zr-MOFs. The following are three influencing factors that control this distance: Firstly, the configuration of the organic linker. The organic linkers of all the above-mentioned Zr-MOFs with high water cycle stability have some structural similarities. Except for MIP-200 and MIP-203, the organic linkers of all Zr-MOFs have the same part, namely phthalic acid (as shown in the a region of Figure 3 and Figure 4 ). When these organic linkers containing phthalic acid parts are used to construct Zr-MOFs in the scu -, csq -, alb -, and bcu -types, the unsaturated coordination sites of adjacent Zr 6 nodes along the one-dimensional pore direction can be arranged in a coplanar manner and maintain an appropriate distance to block the introduction of any coplanar water molecules interacting with the nodes. However, comparing PCN-224 and NU-600 reveals that the phthalic acid part does not always ensure a close enough Zr 6 distance, but depends on the specific topological structure. For the she topological network, the dihedral angle between the terminal benzoic acid and Zr 6 is close to 90°, which makes the unsaturated sites of adjacent Zr 6 nodes non-coplanar with each other. Therefore, water molecules are more likely to contact Zr 6nodes, which makes the structure prone to collapse during the water vapor adsorption cycle.

[0048] Second, the length of the organic linker. For an X-shaped organic linker, its size can be changed in three dimensions: the core lateral extension ( Figure 4 Middle b area), core longitudinal stretch ( Figure 4 middle c region) and distal arm extension ( Figure 4 However, the phthalic acid portion of the organic linker can only be retained if the core is extended laterally. Figure 4 The organic linker shown in region b is synthesized with csq The topologically networked ISO-NU-1000 indeed exhibits excellent water adsorption cyclic stability. In contrast, longitudinally stretching the core of the X-shaped organic linker in the same-grid synthesis will directly increase the adjacent Zr 6 The distance between the nodes is reduced, resulting in a structure with poor water adsorption cycle stability. For example, the structure with csq The NU-1000 network has scu The topological network of NU-901 is difficult to resist the capillary force during water desorption. 6 Similar to the change in node distance, organic linkers with the same configuration but different end arm lengths also lead to the Zr 6 The node distance changes. For example, in WSU-5, the extension of the organic linker end arm makes the Zr 6 The node distance becomes wider, resulting in poor structural stability of WSU-5. In another pair of Zr-MOFs with the same grid but different lengths of organic linker end arms, the Zr 6 The node distance is limited, showing extremely high water adsorption cyclic stability, but Zr-PEP-2 cannot maintain its complete porosity even with conventional vacuum thermal activation schemes due to the long end arms of the organic linkers.

[0049] Third, the arm angle of the organic linker. When the organic linker has a phthalic acid moiety, the angle between the two arms is about 60°. 6 The distance between nodes can be controlled within 5 Å. However, when the core changes from a six-membered ring to a five-membered ring ( Figure 4 When the Zr-TTF is constructed by the organic linker of the five-membered ring core, the coplanar Zr 6 The node distance increases to 5.7 Å. Therefore, Zr-TTF cannot resist the capillary force during water adsorption and desorption, resulting in structural collapse in the second water adsorption cycle.

[0050] In summary, the phthalic acid moiety can be effectively retained by lateral stretching of the core of the X-shaped organic linker, which will be the limit of the adjacent coplanar Zr 6 The optimal scheme for the accessibility of water molecules at the node. According to the above rules, Zr-MOFs with high water adsorption cycle stability can be designed and synthesized for air water collection or indoor humidity control. 4 The TPTA linker, whether contracting or stretching its core laterally, can yield Zr-MOFs with one-dimensional pores and high water adsorption cycle stability.

[0051] When the organic linker Figure 5 When the area a in the middle is shortened, it is H 4 TCPE organic linker, and can be used to synthesize a scu The topological structure of Zr-MOF is called Zr-TCPE. Zr-TCPE has a typical one-dimensional pore, and along the pore direction, Zr 6 The unsaturated sites of adjacent Zr 6 The finite distance between them is less than 5.2 Å, which satisfies the necessary conditions for high water adsorption cycle stability of Zr-MOFs. Therefore, Zr-TCPE exhibits excellent water adsorption cycle stability, although the subsequent adsorption cycles show a slightly decreased saturation adsorption capacity compared to the first cycle ( Figure 5 However, after the sample was reactivated at 120°C for 10 hours, the nitrogen adsorption isotherm was still completely consistent with that of the fresh sample ( Figure 5 This indicates that the porosity of Zr-TCPE remains intact after multiple rounds of water adsorption.

[0052] Horizontal stretch H 4 TPTA linker can obtain H 4 PyQ( Figure 5 Using this new organic linker, a new microporous Zr-MOF (NJTech-5) was successfully synthesized in DMF. According to the experimental PXRD pattern of NJTech-5 ( Figure 5 As can be seen from the area b in the figure, NJTech-5 P 6 / m The space group crystallizes in the hexagonal system, which consists of 12 connected Zr 6 Node and H 4 PyQ linker, with shp The crystal structure of NJTech-5 shows that it also meets the necessary conditions for being a Zr-MOFs with high water adsorption cycle stability, that is, it contains a one-dimensional 1.2 nm triangular pore ( Figure 5In the c region), coplanar Zr along the pore direction 6 The distance between the nodes is 3.9 Å( Figure 5 In the d region). Therefore, NJTech-5 has high water adsorption cycle stability.

[0053] To characterize the porosity of NJTech-5, the powder sample was subjected to solvent exchange with acetone and further evacuated at 120 °C for 16 hours to obtain an activated sample. According to N 2 isotherm( Figure 5 In the g region), the BET surface area of NJTech-5 is 1730 m 2 g -1 . From the N 2 isotherm-calculated pore size distribution (PSD) indicates that there are micropores with diameters of 1.1 - 1.5 nm in NJTech-5, which is consistent with its crystal structure. Further water adsorption experiments show that it has a high water adsorption capacity of 0.93 g g -1 , belonging to the category of MOFs with high water adsorption capacity( Figure 5 In the h-i region). At the same time, kinetic studies were carried out on NJTech-5 at 60% relative humidity (RH), and water adsorption and release were carried out at 298 K. As Figure 5 shown in the j region, NJTech-5 reaches saturated water adsorption within 360 minutes at 298 K, with a capacity of 0.89 g g -1 , and 90% of the adsorbed water can be released within 30 minutes at 298 K, showing a fast dehydration rate of 1.78 L kg -1 h -1 .

[0054] The cycle stability of NJTech-5 was further tested through multiple water adsorption-desorption cycles. As Figure 5 shown in the j region, after 20 water vapor kinetic cycles, the adsorption capacity of NJTech-5 still retains 90% of its initial capacity. Further activation by the thermal vacuum method can maintain the N 2 adsorption capacity at 77 K similar to the initial adsorption amount, indicating that NJTech-5 has the expected good water adsorption cycle stability.

[0055] In summary, this application reveals a mechanism for restricting the water molecule accessibility of Zr 6 nodes in Zr-MOFs through a series of zirconium-based metal-organic framework materials (Zr-MOFs) with high water adsorption cycle stability. According to this mechanism, certain topological structures can regulate Zr 6Nodes, thus successfully restricting the introduction of water molecules in the plane and significantly improving the cyclic stability of Zr-MOFs in water adsorption. Based on this mechanism, this application proposes an organic linker design strategy, that is, to achieve the isostructural synthesis of Zr-MOFs by laterally stretching the core of the organic linker. Whether shrinking or stretching the horizontal length of the organic linker core, the resulting MOFs all exhibit high cyclic stability in water adsorption. Among them, NJTech-5, as a new type of zirconium-based metal-organic framework with shp topology, has high water absorption capacity and is one of the potential candidate materials for humidity control.

Claims

1. A zirconium-based metal organic framework material, characterized in that: Each Zr6 cluster node is coordinated with 12 X-type organic linkers 4,4',4'',4'''-(pyrazino[2,3-g]quinoxaline-2,3,7,8-tetrayl)tetrabenzoic acid (H4PyQ) with 4-connectivity, and each X-type organic linker H4PyQ is coordinated with four Zr6 clusters with 12-connectivity; among them, the Zr6 cluster nodes are linearly arranged along the one-dimensional channel with co-planar chelated formate groups; the distance between adjacent Zr6 cluster formate oxygens along the channel direction is ≤5.4 Å.

2. The method for preparing the zirconium-based metal organic framework material according to claim 1, characterized in that: The method comprises dissolving H4PyQ, zirconium tetrachloride and a template in DMF, and dispersing the mixture in a mixture of DMF and an acid solution after heating and washing once, and then performing secondary heating to remove the template, centrifuging, washing, replacing with a low boiling point solvent, drying and activating.

3. The method for preparing a zirconium-based metal organic framework material according to claim 2, characterized in that: The template agent is propionic acid; The addition ratio of zirconium tetrachloride, H4PyQ and propionic acid is (5~10) mg:(8~12) mg:(1~5) mL.

4. The method for preparing a zirconium-based metal organic framework material according to claim 2, characterized in that: The conditions for primary heating are: 100~140℃, 15~20 hours; The conditions for secondary heating are: 100~140℃, 15~20 hours; Drying conditions are: 50~75℃, 1~2 hours under non-vacuum conditions; The activation conditions are: under vacuum conditions, 80~140℃, 10~15 hours.

5. The method for preparing a zirconium-based metal organic framework material according to claim 1, characterized in that: The washing is performed with an organic solvent, and the low-boiling point solvent replacement is performed with acetone.

6. Use of the zirconium-based metal organic framework material according to claim 1 in water vapor adsorption and desorption.

7. A zirconium-based metal organic framework material containing one-dimensional channels, characterized in that: The material contains one-dimensional pores, and the Zr6 cluster chelated coordinated formate is on the same plane, and the distance between the formate oxygen atoms of adjacent Zr6 clusters is ≤5.4 Å.

8. The zirconium-based metal organic framework material containing one-dimensional channels according to claim 7, characterized in that: The topological structure of the zirconium-based metal organic framework material is bct type, csq type, scu type, shp type.

9. The zirconium-based metal organic framework material containing one-dimensional channels according to claim 7, characterized in that: The combination of channels can produce kgm , sql , kgd and bex Any cross section in The ligand in the zirconium-based metal organic framework material is one or more of H2TCPP, H4TCPB-Br2, H4MDIP, fumaric acid, H4TPTA, H6PET, H4ETTC, H4TTFTB, H4TCPE, and H4PyQ.

10. A method for improving the water adsorption cycle stability of zirconium-based metal organic framework materials is to provide an organic linker with an "o-dibenzoic acid" unit when preparing the metal organic framework material, and to extend the length of the organic linker axially along the symmetry axis of the "o-dibenzoic acid" unit.

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