Metal organic complex and method for producing the same

Abstract

The application relates to the technical field of metal organic framework material preparation, and provides a metal organic compound and a preparation method thereof, the molecular formula of the metal organic compound is Zr6O m (OH) n (OL) 6‑(x+y) / 2 (sol) x (blank) y N b , 4<=m<=6, 0<=n<=4, 0.09<=x<=0.92, 1.8<=y<=6.02, 0.9<=b<=6.94; wherein, OL is a double-carboxyl conjugated organic ligand, sol includes at least one of acetate, formate and CH3(CH2) p COO ‑ , 1<=p<=6, blank is a ligand vacancy, and N is a counter ion; the unsaturated coordination defect rate of the metal organic compound is 15%-50.1%.

Description

Technical Field

[0001] This application relates to the field of metal-organic framework material preparation technology, and in particular to a metal-organic composite and its preparation method. Background Technology

[0002] Defects in MOF materials possess unique spatial structures and electronic properties, providing active sites for chemical reactions and leading to their widespread application in catalysis, adsorption, and many other fields. Therefore, defect engineering has become a perennial research direction in crystalline nanomaterials. Metal-organic frameworks (MOFs) are crystalline framework materials with intramolecular pores formed by the self-assembly of metal ions or clusters with organic ligands under certain conditions through coordination bonds. Compared to other nanomaterials, MOFs have a larger specific surface area, tunable pore size and shape, and are easily modified, showing broad application prospects in catalysis, separation and purification, gas adsorption, and energy. Introducing defects into the crystal structure of MOFs can regulate their structure and improve adsorption performance, catalytic activity, and conductivity. During the preparation of MOFs, solvent / template substitution leading to organic ligand loss, unsaturated coordination, organic ligand doping, and metal node loss all result in defects within the MOFs.

[0003] However, excessively high defect concentrations can lead to reduced connectivity between the metal framework and ligands and an increase in unstable nodes within the metal-organic framework (MOF), thus limiting the improvement of the MOF defect rate. Taking UiO-66 as an example, its theoretical maximum defect rate is 36.6%. Among various defect types, unsaturated coordination often exhibits higher activity; however, the occupation of polar solvents, adsorption of impurities, and coordination of template agents can all lead to the elimination of unsaturated coordination. Therefore, improving the unsaturated coordination defect rate within MOFs while simultaneously preparing high-defect-rate MOFs holds significant promise for future applications. Summary of the Invention

[0004] The purpose of this application is to provide a metal-organic composite and its preparation method, so as to improve the total defect rate and unsaturated coordination defect rate of the metal-organic composite. The specific technical solution is as follows:

[0005] The first aspect of this application provides a metal-organic composite with the molecular formula Zr6O. m (OH) n (OL) 6-(x+y) / 2 (sol) x (blank) y N b, 4≤m≤6, 0≤n≤4, 0.09≤x≤0.92, 1.8≤y≤6.02, 0.9≤b≤6.94; where OL is a dicarboxylic acid conjugated organic ligand, and sol includes acetate, formate and CH3(CH2). p COO - At least one of the following, 1≤p≤6, blank is a ligand vacancy, and N is a counter ion.

[0006] In some embodiments of this application, the molar ratio of Zr to OL in the organometallic composite is 6:(2.53~5.055).

[0007] In some embodiments of this application, the molar ratio of Zr to OL in the organometallic compound is 6:(2.766~4.932).

[0008] In some embodiments of this application, the molar ratio of Zr to OL in the organometallic composite is 6:(2.766~3.996).

[0009] In some embodiments of this application, the molar ratio of Zr to OL in the organometallic compound is 6:(2.766~3.51).

[0010] In some embodiments of this application, the organometallic complex comprises a cationic framework and an in-pore adsorbent component.

[0011] In some embodiments of this application, the dicarboxylated conjugated organic ligand comprises a molecular skeleton, which includes any one of phenyl, pyridyl, and imidazole groups.

[0012] In some embodiments of this application, when the molecular skeleton is phenyl, the dicarboxylate conjugated organic ligand includes at least one of terephthalate, isophthalate, and phthalate.

[0013] In some embodiments of this application, when the molecular skeleton is phenyl, the dicarboxylic acid conjugated organic ligand includes functional group X, which includes any one of amino, hydroxyl, mercapto, methoxy, nitro, fluorine, and chlorine groups.

[0014] In some embodiments of this application, the dicarboxylated conjugated organic ligand comprises at least one of the following substances:

[0015] (1) When the functional group X is an amino group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-aminoterephthalate, 2,5-diaminoterephthalate, 2,3-diaminoterephthalate, 2,3,5-triaminoterephthalate and 2,3,4,5-tetraaminoterephthalate.

[0016] (2) When the functional group X is a hydroxyl group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-hydroxyterephthalate, 2,5-dihydroxyterephthalate, 2,3-dihydroxyterephthalate, 2,3,5-trihydroxyterephthalate and 2,3,4,5-tetrahydroxyterephthalate;

[0017] (3) When the functional group X is a thiol group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-mercaptoterephthalate, 2,5-dimercaptoterephthalate, 2,3-dimercaptoterephthalate, 2,3,5-trimercaptoterephthalate and 2,3,4,5-tetramercaptoterephthalate;

[0018] (4) When the functional group X is methoxy, the dicarboxylic acid conjugated organic ligand includes at least one of 2-methoxyterephthalate, 2,5-dimethoxyterephthalate, 2,3-dimethoxyterephthalate, 2,3,5-trimethoxyterephthalate and 2,3,4,5-tetramethoxyterephthalate;

[0019] (5) When the functional group X is a nitro group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-nitroterephthalate, 2,5-dinitroterephthalate, 2,3-dinitroterephthalate, 2,3,5-trinitroterephthalate and 2,3,4,5-tetranitroterephthalate;

[0020] (6) When the functional group X is a fluorine group, the dicarboxylic acid conjugated organic ligand includes at least one of 2,5-dicarboxyfluorobenzoate, 2,5-difluoroterephthalate, 2,3-difluoroterephthalate, 2,3,5-trifluoroterephthalate and 2,3,4,5-tetrafluoroterephthalate;

[0021] (7) When the functional group X is a chlorine group, the dicarboxylic conjugated organic ligand includes at least one of 2,5-dicarboxychlorophthalate, 2,5-dichloroterephthalate, 2,3-dichloroterephthalate, 2,3,5-trichloroterephthalate and 2,3,4,5-tetrachloroterephthalate.

[0022] In some embodiments of this application, the molecular skeleton is selected from either pyridyl or imidazolyl, and the dicarboxylated conjugated organic ligand comprises at least one of the following substances:

[0023] (1) When the molecular skeleton is selected from pyridinyl, the dicarboxylic acid conjugated organic ligand includes 2,5-pyridinic acid dicarboxylate;

[0024] (2) When the molecular skeleton is selected from imidazole, the dicarboxylic conjugated organic ligand includes at least one of 1H-imidazol-2,4-dicarboxylate and imidazol-4,5-dicarboxylate.

[0025] In some embodiments of this application, the counterion includes NO3. - Cl - SO4 2- ,Br - acetylacetone and F - At least one of them.

[0026] In some embodiments of this application, the unsaturated coordination defect rate of the organometallic composite is 15% to 50.1%, preferably 26.1% to 50.1%, more preferably 30.7% to 50.1%, and even more preferably 37% to 50.1%.

[0027] In some embodiments of this application, thermogravimetric analysis is used to test the total defect rate of the metal-organic composite, which is 20% to 53.5%, preferably 29.6% to 53.5%, more preferably 32.9% to 53.5%, and even more preferably 41% to 53.5%.

[0028] In some embodiments of this application, the average particle size of the organometallic composite is 20 nm to 125 nm.

[0029] A second aspect of this application provides a method for preparing a metal-organic composite, comprising the following steps:

[0030] (1) A reaction system is obtained by adding zirconium salt and dicarboxylic acid conjugated organic ligand to a mixed solution of deionized water and template agent; wherein the reaction system is a suspension system, and the molar concentration of zirconium salt is 300 mmol / L to 600 mmol / L based on the volume of the reaction system; the molar ratio of zirconium salt to dicarboxylic acid conjugated organic ligand is 1:(0.6~2), and the molar ratio of zirconium salt to template agent is (0.02~0.3):1;

[0031] (2) The reaction system is mechanically stirred and heated at a temperature of 60°C to 120°C for a time of 1 h to 168 h. The crude product of the metal-organic complex is obtained by solid-liquid separation.

[0032] (3) The crude product of the organometallic compound is washed and separated to obtain the organometallic compound.

[0033] In some embodiments of this application, the zirconium salt includes at least one selected from zirconium oxynitrate, zirconium chloride, zirconium oxychloride, zirconium bromide, zirconium fluoride, zirconium acetylacetonate, and zirconium sulfate; the template agent includes glacial acetic acid, formic acid, hydrochloric acid, and CH3(CH2). p At least one of COOH, 1≤p≤6; the organometallic compound has the molecular formula Zr6O m (OH) n (OL) 6-(x+y) / 2 (sol) x (blank) y N b , 4≤m≤6, 0≤n≤4, 0.09≤x≤0.92, 1.8≤y≤6.02, 0.9≤b≤6.94; where OL is a dicarboxylic acid conjugated organic ligand, and sol includes acetate, formate, and CH3(CH2). p COO - At least one of the following, 1≤p≤6, blank is a ligand vacancy, and N is a counter ion.

[0034] In some embodiments of this application, a drying step is included after the separation step described in step (3).

[0035] The beneficial effects of this application are:

[0036] This application provides a metal-organic composite and its preparation method, wherein the molecular formula of the metal-organic composite is Zr6O. m (OH) n (OL) 6-(x+y) / 2 (sol) x (blank) y N b , 4≤m≤6, 0≤n≤4, 0.09≤x≤0.92, 1.8≤y≤6.02, 0.9≤b≤6.94; where OL is a dicarboxylic acid conjugated organic ligand, and sol includes acetate, formate, and CH3-(CH2). p -COO - At least one of the following, 1≤p≤6, blank represents a ligand vacancy, and N represents a counter ion. Organometallic compounds conforming to the above molecular formula have a high total defect rate and unsaturated coordination defect rate, which can give them more highly active sites, thereby improving their catalytic activity, adsorption capacity for gases, toxic substances, and dyes, and charge transfer capacity.

[0037] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these accompanying drawings.

[0039] Figure 1 This is a schematic diagram of the structure of a metal-organic compound;

[0040] Figure 2 Infrared spectra of the organometallic complexes in Examples 1 and 7;

[0041] Figure 3 The infrared spectrum of the organometallic compound in Example 12;

[0042] Figure 4 The infrared spectrum of the organometallic compound in Example 14;

[0043] Figure 5 The XRD patterns of the organometallic complexes in Examples 1 and 11 are shown below.

[0044] Figure 6 This is the solid-state NMR phosphorus spectrum of the organometallic complex labeled with TMPO in Example 3.

[0045] Figure 1 In the diagram, 1 represents a zirconium atom, 2 represents an oxygen atom, 3 represents a dicarboxylic acid conjugated organic ligand, and 4 represents a missing dicarboxylic acid conjugated organic ligand. Detailed Implementation

[0046] The technical solutions of this application will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0047] The first aspect of this application provides a metal-organic composite with the molecular formula Zr6O. m (OH) n (OL) 6-(x+y) / 2 (sol) x (blank) y N bThe formula is: 4≤m≤6, 0≤n≤4, 0.09≤x≤0.92, 1.8≤y≤6.02, 0.9≤b≤6.94. For example, the value of m can be 4, 4.3, 4.5, 4.8, 5, 5.3, 5.5, 5.8, 6, or any range of two such values; the value of n can be 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, or any range of two such values; the value of x can be 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, ... The values ​​for 0.9, 0.92, or any two of these values ​​can be within a range; the values ​​for y can be 1.8, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.02, or any two of these values; the values ​​for b can be 0.9, 1, 1.5, 1.8, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.02, 6.5, 6.94, or any two of these values. Wherein, OL represents a dicarboxylic acid conjugated organic ligand, and sol includes acetate, formate, and CH3(CH2). p COO - At least one of the following, 1≤p≤6, blank is a ligand vacancy, and N is a counter ion.

[0048] Generally, based on the charge characteristics of the metal framework, the metal frameworks of organometallic compounds (MMCs) can be classified into cationic frameworks, anionic frameworks, and neutral frameworks. In some embodiments of this application, the MMC comprises a cationic framework and an in-pore adsorbed component. The cationic framework refers to a framework exhibiting cationic properties, and the in-pore adsorbed component includes counter ions. These counter ions are weakly bound to the metal framework through non-covalent interactions and are essential for maintaining the charge neutrality of the MMC. The role of the counter ions is to balance the charge of the cationic framework caused by defects. For example, for the cationic framework in the MMC of this application, the counter ion is NO3. - Cl - SO4 2- ,Br - acetylacetone and F - Counterions can be used to replace other ions of the same charge in the dissolution reaction system, thereby affecting the performance of organometallic compounds in various fields, such as ion removal, uptake, detection, drug loading and release, proton transport, dye removal, catalysis, gas adsorption and separation, and fluorescence. Furthermore, since solvents and template agents are used in the preparation of organometallic compounds, the adsorbed components within the pores of the prepared organometallic compounds also include adsorbed solvents and / or adsorbed template agents; this application does not specifically limit the types and contents of other adsorbed components.

[0049] The zirconium-oxygen cluster nodes of UiO series metal-organic composites are typically represented as Zr6O4(OH)4 (i.e., m=4, n=4), a designation that has gained industry consensus. However, during post-processing such as heating and vacuum treatment, the hydroxyl groups at the zirconium-oxygen cluster nodes may dehydrate and partially detach, potentially forming a Zr6O6 structure in extreme cases. Due to limitations in current characterization techniques, the hydroxyl content at the zirconium-oxygen cluster nodes cannot be precisely quantified. Therefore, in this application, the molecular formula of the metal-organic composite is described as "Zr6O4(OH)4". m (OH) n (OL) 6(x+y) / 2 (sol) x (blank) y N b ", where 4≤m≤6, 0≤n≤4, 0.09≤x≤0.92, 1.8≤y≤6.02, and 0.9≤b≤6.94.

[0050] The unsaturated coordination defect rate of the metal-organic complex is 15% to 50.1%. For example, the unsaturated coordination defect rate of the metal-organic complex can be 15%, 20%, 25%, 26.1%, 30%, 30.7%, 35%, 37%, 40%, 45%, 49%, 50%, 50.1%, or a range of any two values ​​therein. The unsaturated coordination defect rate in this application is measured using solid-state phosphorus NMR spectroscopy, and the corresponding test method is described in the Test Methods and Equipment section of this application specification.

[0051] Defects in MOF materials play a crucial role as active sites in adsorption and catalytic reactions due to their unique spatial structure and electronic properties. Unsaturated coordination defects, caused by the absence of dicarboxylic acid conjugated organic ligands, exhibit higher activity compared to other types of defects. Exposed unsaturated metal sites possess lower steric hindrance and higher site accessibility, enabling them to effectively adsorb and activate catalytic substrate molecules. Furthermore, unsaturated coordination sites typically have lower metal valence states, resulting in a charge distribution within the material and a charge transfer pathway with the substrate that differs significantly from saturated coordination structures. This unique charge distribution and transfer pathway are more conducive to molecular activation and electron migration, thereby enhancing the material's relevant application performance. Controlling the unsaturated coordination defect rate within the range described in this application can improve the catalytic, adsorption, and charge transfer capabilities of metal-organic complexes.

[0052] In some embodiments of this application, the molar ratio of Zr to OL in the organometallic composite is 6:(2.53~5.055), preferably 6:(2.766~4.932), more preferably 6:(2.766~3.996), and even more preferably 6:(2.766~3.51). For example, the molar ratio of Zr to OL in the organometallic composite can be 6:2.53, 6:2.766, 6:3, 6:3.44, 6:3.51, 6:3.996, 6:4.266, 6:4.5, 6:4.932, 6:5.055, or a range of any two of these values. In the organometallic composite, the molar ratio of Zr to OL actually reflects the total defect rate of the material. Theoretically, the total defect rate = 1 - n(OL) / n(Zr). Controlling the molar ratio of Zr to OL within the range of this application helps to ensure that the defect rate is within a suitable range.

[0053] In some embodiments of this application, the dicarboxylated conjugated organic ligand includes a molecular skeleton, which includes any one of phenyl, pyridyl, and imidazolyl groups.

[0054] In some embodiments of this application, when the molecular skeleton is phenyl, the dicarboxylate conjugated organic ligand includes at least one of terephthalate, isophthalate, and phthalate.

[0055] In some embodiments of this application, when the molecular skeleton is phenyl, the dicarboxylic acid conjugated organic ligand includes a functional group X, which includes any one of amino, hydroxyl, mercapto, methoxy, nitro, fluorine, and chlorine groups. Introducing functional group X into the organometallic complex and controlling the type of functional group X within the scope of this application is beneficial for adjusting the polarity of the pore wall of the organometallic complex, thereby enhancing the interaction between its pore wall and the adsorbed and catalytic substrate, promoting the adsorption of the substrate in the pore, and thus improving the catalytic ability, adsorption capacity, and charge transfer ability of the organometallic complex.

[0056] In some embodiments of this application, the dicarboxylated conjugated organic ligand comprises at least one of the following substances:

[0057] (1) When the functional group X is an amino group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-aminoterephthalate, 2,5-diaminoterephthalate, 2,3-diaminoterephthalate, 2,3,5-triaminoterephthalate and 2,3,4,5-tetraaminoterephthalate.

[0058] (2) When the functional group X is a hydroxyl group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-hydroxyterephthalate, 2,5-dihydroxyterephthalate, 2,3-dihydroxyterephthalate, 2,3,5-trihydroxyterephthalate and 2,3,4,5-tetrahydroxyterephthalate;

[0059] (3) When the functional group X is a thiol group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-mercaptoterephthalate, 2,5-dimercaptoterephthalate, 2,3-dimercaptoterephthalate, 2,3,5-trimercaptoterephthalate and 2,3,4,5-tetramercaptoterephthalate;

[0060] (4) When the functional group X is methoxy, the dicarboxylic acid conjugated organic ligand includes at least one of 2-methoxyterephthalate, 2,5-dimethoxyterephthalate, 2,3-dimethoxyterephthalate, 2,3,5-trimethoxyterephthalate and 2,3,4,5-tetramethoxyterephthalate;

[0061] (5) When the functional group X is a nitro group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-nitroterephthalate, 2,5-dinitroterephthalate, 2,3-dinitroterephthalate, 2,3,5-trinitroterephthalate and 2,3,4,5-tetranitroterephthalate;

[0062] (6) When the functional group X is a fluorine group, the dicarboxylic acid conjugated organic ligand includes at least one of 2,5-dicarboxyfluorobenzoate, 2,5-difluoroterephthalate, 2,3-difluoroterephthalate, 2,3,5-trifluoroterephthalate and 2,3,4,5-tetrafluoroterephthalate;

[0063] (7) When the functional group X is a chlorine group, the dicarboxylic conjugated organic ligand includes at least one of 2,5-dicarboxychlorophthalate, 2,5-dichloroterephthalate, 2,3-dichloroterephthalate, 2,3,5-trichloroterephthalate and 2,3,4,5-tetrachloroterephthalate.

[0064] In some embodiments of this application, the molecular skeleton is selected from either pyridyl or imidazole, and the dicarboxylated conjugated organic ligand includes at least one of the following: (1) when the molecular skeleton is selected from pyridyl, the dicarboxylated conjugated organic ligand includes 2,5-pyridinic acid dicarboxylate; (2) when the molecular skeleton is selected from imidazole, the dicarboxylated conjugated organic ligand includes at least one of 1H-imidazolium-2,4-dicarboxylate and imidazolium-4,5-dicarboxylate. When the molecular skeleton of the dicarboxylated conjugated organic ligand includes imidazole and pyridyl, the dicarboxylated conjugated organic ligand skeleton itself contains heteroatoms, which is beneficial for adjusting the polarity of the pore wall of the organometallic complex, thereby enhancing the interaction between its pore wall and the adsorbed and catalytic substrate, promoting the adsorption of the substrate in the pore, and thus improving the catalytic ability, adsorption ability and charge transfer ability of the organometallic complex.

[0065] In this application, functional group X has a significant impact on the steric hindrance of the metal-organic complex. Simultaneously, functional group X itself acts as an active site for Lewis acids or bases, altering the affinity of the pores for external guest molecules. Furthermore, functional group X is electronegative, influencing the electronic structure at the nodes; electron-withdrawing groups enhance the Lewis acidity of the nodes, and vice versa. Within the scope of this application, suitable functional groups and dicarboxylic acid conjugated organic ligands can be selected according to practical application requirements to achieve optimal electronic and spatial structures.

[0066] Figure 2 The images show the infrared spectra of the organometallic complexes in Examples 1 and 7. The organometallic complexes are spectral at 1630 cm⁻¹. -1 and 1260cm -1 The absorption peaks at 1384 cm⁻¹ represent the NH and CN vibrations of the amino group on the benzene ring, respectively, indicating that the organometallic complex contains the functional group amino. Meanwhile, the two samples from Examples 1 and 7 also showed absorption peaks at 1384 cm⁻¹. -1 1430 cm -1 1500 cm -1 and 1574 cm -1 Both exhibited significant carboxyl vibrations, with the two groups resembling a carboxyl group at 770 cm⁻¹. -1 and 665 cm -1 The two distinct absorption peaks directly indicate the presence of Zr-O bonds. Figure 3 The infrared spectrum of the organometallic compound in Example 12 is shown below. The organometallic compound has an infrared spectrum at 1245 cm⁻¹. -1 and 1230 cm -1 The presence of absorption peaks indicates that the organometallic compound contains fluorine groups. Figure 4 The infrared spectrum of the organometallic compound in Example 14 is shown below. The organometallic compound has an infrared spectrum at 1624 cm⁻¹. -1The presence of an absorption peak around a pyridine ring indicates that the organometallic complex contains a pyridine group.

[0067] In this application, sol refers to a small molecule ligand, and blank refers to a ligand vacancy appearing around Zr. Sol is introduced during the preparation process via a template agent. Depending on the preparation conditions, sol may be partially substituted by polar molecules such as ethanol, dichloromethane, water, or the template agent. This application does not specifically limit the polar molecules; any molecule that achieves the purpose of this application is acceptable. For example, in the embodiments of this application, when sol is selected from acetate, it includes the possibility of partial substitution by the solvent.

[0068] In some embodiments of this application, the counterion includes NO3. - Cl - SO4 2- ,Br - acetylacetone and F - At least one of them.

[0069] Based on the charge characteristics of the metal framework, the metal frameworks of organometallic compounds (MMCs) can be classified into cationic frameworks, anionic frameworks, and neutral frameworks. Counterions, weakly bound to the metal framework through non-covalent interactions, are essential for maintaining the charge neutrality of MMCs. The role of counterions is to balance the charge of the cationic framework caused by defects. For cationic frameworks in MMCs, the counterion is NO3-. - Cl - SO4 2- ,Br - acetylacetone and F - Counterions can influence the performance of organometallic compounds in various fields, such as ion removal, uptake, detection, drug loading and release, proton transport, dye removal, catalysis, gas adsorption and separation, and fluorescence, by dissolving and replacing other ions of the same charge in the reaction system.

[0070] In some embodiments of this application, solid-state NMR phosphorus spectroscopy is used to determine that the unsaturated coordination defect rate of the organometallic complex is 26.1% to 50.1%, preferably 30.7% to 50.1%, and more preferably 37% to 50.1%. For example, the unsaturated coordination defect rate of the organometallic complex can be 26.1%, 28%, 30%, 30.7%, 32%, 35%, 37%, 40%, 43%, 45%, 47%, 49%, 50%, 50.1%, or a range consisting of any two of these values. Unsaturated coordination defects refer to defect structures caused by the absence of dicarboxyl conjugated ligands. Compared with other types of defects, unsaturated coordination defects have higher activity; exposed unsaturated metal sites have lower steric hindrance and higher site accessibility, which allows them to more effectively adsorb and activate catalytic substrate molecules. Furthermore, unsaturated coordination sites typically have lower metal valence states, resulting in a charge distribution within the material and a charge transfer path with the substrate that is significantly different from that of saturated coordination structures. By controlling the unsaturated coordination defects of organometallic compounds within the scope of this application, this unique charge distribution and transfer pathway is more conducive to molecular activation and electron migration, thereby improving the relevant application performance of organometallic compounds.

[0071] In some embodiments of this application, thermogravimetric analysis is used to test the total defect rate of the organometallic complex, which is 20% to 53.5%, preferably 29.6% to 53.5%, more preferably 32.9% to 53.5%, and even more preferably 41% to 53.5%. For example, the total defect rate of the organometallic complex can be 20%, 23%, 25%, 27%, 29.6%, 30%, 32.9%, 35%, 38%, 40%, 41%, 43%, 45%, 48%, 50%, 53%, 53.5%, or a range of any two of these values. Introducing defects into the organometallic complex can adjust its structure and improve its adsorption performance, catalytic activity, and band structure energy. The total defect rate refers to the ratio of the number of defects present in the organometallic complex structure to the number of corresponding conjugated dicarboxyl organic ligands in the theoretically intact structure. When the total defect rate of the organometallic complex is too low, its catalytic ability, adsorption capacity, and charge transfer ability are weak; when the total defect rate of the organometallic complex is too high, its structure is unstable. By controlling the total defect rate of the organometallic compound within the range specified in this application, the catalytic ability, adsorption capacity for gases, toxic substances and dyes, and charge transfer capacity of the organometallic compound can be improved.

[0072] In some embodiments of this application, the average particle size of the metal-organic composite is 15 nm to 125 nm, preferably 56 nm to 78 nm. For example, the average particle size of the metal-organic composite can be 15 nm, 20 nm, 30 nm, 50 nm, 56 nm, 70 nm, 78 nm, 80 nm, 100 nm, 120 nm, 125 nm, or a range consisting of any two of these values. In fact, particle size at the nanoscale has a profound impact on material properties. We can observe effects such as quantum size effects in semiconductor materials, improved catalytic performance of inert noble metals, and changes in the conductivity of insulators. By controlling the particle size of the metal-organic composite within the range specified in this application, the size of the metal-organic composite is reduced to the nanoscale. In the region near the outer surface of the metal-organic composite, the proportion of atoms is relatively high. Compared with the atoms inside the metal-organic composite, these atoms on the outer surface have more open cavity spaces. This structural feature expands the interfacial area for the interaction between the substrate and the metal-organic composite, while shortening the diffusion and desorption paths of the substrate. This optimized structural layout is beneficial to improving the application performance of the metal-organic composite, endowing the metal-organic composite with a series of enhanced properties and new characteristics. For example, in the fields of catalysis, sensing, and biomedicine, nanoscale metal-organic composites have better flexibility and optical properties.

[0073] When the particle size of a material is too large, the bulk diffusion paths of its ions / molecules increase significantly, resulting in slow mass transfer kinetics; simultaneously, the specific surface area decreases sharply, leading to an insufficient number of effective surface reaction sites. Both of these factors jointly limit the material's performance. Correspondingly, larger particle sizes usually mean higher crystallinity and a more complete structure, thus resulting in a lower total defect rate, especially a scarcity of highly reactive unsaturated coordination defects. When the particle size is too small, on the one hand, the surface energy is too high, making agglomeration highly likely, which reduces the effective surface area; on the other hand, excessively high defect density (especially a large number of unsaturated coordination defects) may disrupt the long-range ordered structure of the material, leading to decreased structural stability and potentially inducing the continuous occurrence of side reactions. Therefore, while small particle size significantly increases both the total defect rate and the unsaturated coordination defect rate, it also introduces the risks of agglomeration and structural instability.

[0074] In this application, the crystal structure of the organometallic compound is a face-centered cubic structure. Figure 1This is a schematic diagram of a metal-organic compound (MOC), where 1 represents a zirconium atom, 2 an oxygen atom, 3 a dicarboxylic acid conjugated organic ligand, and 4 represents a missing dicarboxylic acid conjugated organic ligand. In MOCs, zirconium atoms, oxygen atoms, and dicarboxylic acid conjugated organic ligands (with phenyl as an example of a molecular framework) are connected by coordinate bonds, while counter ions and small molecule ligands are weakly bonded to the metal framework through non-covalent interactions. Specifically, a single MOC unit cell contains 6 zirconium atoms, which form octahedral zirconium-oxygen cluster nodes by combining with bridging oxygen and bridging hydroxyl groups. Simultaneously, the zirconium-oxygen clusters coordinate with dicarboxylic acid conjugated organic ligands to form the overall framework structure. In a defect-free perfect crystal, each MOC unit cell can coordinate with 12 dicarboxylic acid conjugated organic ligands, meaning each MOC unit cell can contain 6 dicarboxylic acid conjugated organic ligands. If the chemical bond to be coordinated on a zirconium atom does not coordinate with a dicarboxyl conjugated organic ligand, a defect is formed. When the missing organic ligand is replaced by a solvent or template agent (i.e., a small molecule ligand), or when the missing organic ligand is not occupied by any molecule / ion, it becomes a ligand vacancy (blank). To make the charge properties of the unsaturated coordination defect electrically neutral, an antiion with the same charge must be introduced at the ligand-deficient site, i.e., a counterion.

[0075] A schematic diagram of the structure of a metal-organic compound can be obtained from kinetic simulation (MD), such as... Figure 1 As shown in the figure. In the dynamical simulation, geometry optimization was performed using the CP2K package. The calculations employed the Perdew–Burke–Ernzerhof (PBE) functional, combined with a mixed basis set. The atomic nuclei and inner-shell electrons were described using pseudopotentials recommended by Goedecker, Teter, and Hutter, while valence electrons were treated using a double-zeta polarization (DZVP) basis set. Furthermore, non-covalent interactions were described using the scheme proposed by Grimme et al. The BFGS (Broyden-Fletcher-Goldfarb-Shanno) optimization method was used to optimize the atomic structure and cell parameters throughout the process.

[0076] In some embodiments of this application, the number of functional groups X within a single dicarboxylic acid conjugated organic ligand in the organometallic complex is 1 to 4. For example, the number of functional groups X within a single dicarboxylic acid conjugated organic ligand in the organometallic complex can be 1, 2, 3, 4, or any combination of two such values. The number of functional groups X has a significant impact on steric hindrance of the pores; the more functional groups X, the more significant the steric hindrance effect. Simultaneously, functional groups X themselves act as active sites for Lewis acids or bases, altering the affinity of the pores for external guest molecules; the more functional groups X, the stronger the affinity. Furthermore, the electronegativity of functional groups X also affects the electronic structure at the nodes; an increase in electron-withdrawing groups enhances the Lewis acidity of the nodes, and vice versa. Within the scope of this application, an appropriate number of functional groups X can be selected according to actual application requirements to achieve the optimal electronic and spatial structure.

[0077] In some embodiments of this application, the XRD pattern of the organometallic composite includes diffraction peaks of the (200) and (111) crystal planes. Figure 5 The XRD patterns of the organometallic composites in Examples 1 and 11 are shown. The black vertical line in the lower part of the figure (XRD standard card) is the diffraction peak simulated based on UiO-66 single crystal. It includes the diffraction peaks of the (200) and (111) crystal planes, indicating that the organometallic composite of this application is a UiO-66 series material and has a good crystal structure.

[0078] A second aspect of this application provides a method for preparing a metal-organic composite, comprising the following steps:

[0079] (1) A reaction system is obtained by adding zirconium salt and dicarboxylic acid conjugated organic ligand to a mixed solution of deionized water and template agent; wherein the reaction system is a suspension system, and the molar concentration of zirconium salt is 300 mmol / L to 600 mmol / L based on the volume of the reaction system; the molar ratio of zirconium salt to dicarboxylic acid conjugated organic ligand is 1:(0.6~2), and the molar ratio of zirconium salt to template agent is (0.02~0.3):1;

[0080] (2) The reaction system is mechanically stirred and heated at a temperature of 60°C to 120°C for a time of 1 h to 168 h. The crude product of the metal-organic complex is obtained by solid-liquid separation.

[0081] (3) The crude product of the organometallic compound is washed and separated to obtain the organometallic compound.

[0082] In some embodiments of this application, the zirconium salt includes at least one selected from zirconium oxynitrate, zirconium chloride, zirconium oxychloride, zirconium bromide, zirconium fluoride, zirconium acetylacetonate, and zirconium sulfate; the template agent includes glacial acetic acid, formic acid, hydrochloric acid, and CH3(CH2). p At least one of COOH, 1≤p≤6; the organometallic compound has the molecular formula Zr6O m (OH) n (OL) 6-(x+y) / 2 (sol) x (blank) y N b , 4≤m≤6, 0≤n≤4, 0.09≤x≤0.92, 1.8≤y≤6.02, 0.9≤b≤6.94; where OL is a dicarboxylic acid conjugated organic ligand, and sol includes acetate, formate, and CH3(CH2). p COO - At least one of the following, 1≤p≤6, blank is a ligand vacancy, and N is a counter ion.

[0083] In this application, the zirconium oxynitrate includes zirconium oxynitrate and / or hydrated zirconium oxynitrate, and the zirconium oxychloride includes zirconium oxychloride and / or zirconium oxychloride octahydrate.

[0084] This application uses deionized water as a solvent. The total defect rate, unsaturated coordination defect rate, and morphology of the resulting organometallic complex were adjusted by modifying the amounts of the dicarboxylated conjugated organic ligand, template agent, and zirconium salt. Compared to traditional organic solvents, such as N,N-dimethylformamide (DMF) and N,N-diethylformamide (DEF), the use of aqueous phase synthesis of organometallic complexes offers advantages such as being environmentally friendly and cost-effective. Furthermore, compared to DMF solvent, the faster hydrolysis rate of zirconium salt in water results in more nucleation sites during the growth of the organometallic complex, leading to a higher total defect rate, unsaturated defect rate, and smaller particle size.

[0085] In some embodiments of this application, the molar concentration of the zirconium salt is 300 mmol / L to 600 mmol / L, based on the volume of the reaction system. For example, based on the volume of the reaction system, the molar concentration of the zirconium salt can be 300 mmol / L, 350 mmol / L, 400 mmol / L, 450 mmol / L, 500 mmol / L, 550 mmol / L, 600 mmol / L, or a range of any two of these values. Controlling the molar concentration of the zirconium salt within the range specified in this application results in a higher molar concentration, leading to a supersaturated solution of the zirconium salt. This causes some of the zirconium salt to dissolve in the mixed solution of deionized water and the template agent, while some remains undissolved, thus forming a suspension system. Using the suspension system as the reaction system, with mechanical stirring and heating, zirconium salt and dicarboxylated conjugated organic ligands react with deionized water and a template agent. During the reaction, dissolved zirconium salt and dicarboxylated conjugated organic ligands are consumed, while undissolved zirconium salt and dicarboxylated conjugated organic ligands in the suspension system continue to dissolve, maintaining a high molar concentration of zirconium salt and dicarboxylated conjugated organic ligands. This provides more nucleation sites for the preparation of the organometallic composite, increasing the nucleation rate and slowing the growth rate, which is beneficial for forming organometallic composites with smaller and more uniform particle sizes and higher unsaturated defect rates. Based on the volume of the reaction system, controlling the molar concentration of zirconium salt within the range specified in this application can accelerate the formation rate of zirconium oxide clusters in the organometallic composite, thereby providing more nucleation sites during the preparation process. Furthermore, in this application, compared to the dissolved concentration of zirconium salt, the concentration of dicarboxylated conjugated organic ligands is relatively low, which leads to a slower condensation reaction rate (crystal growth) between them and zirconium oxide clusters. By simultaneously controlling the concentrations of zirconium salt and dicarboxylic acid conjugated organic ligands within the range specified in this application, it is beneficial to form metal-organic complexes with smaller particle sizes and uniform distribution. This allows for more precise control over the nucleation and growth processes, resulting in higher total defect rates and unsaturated coordination defect rates in the metal-organic complexes. If the molar concentration of zirconium salt is too low, the concentration is low, providing fewer nucleation sites, leading to a lower nucleation rate and faster growth rate in the metal-organic complex, resulting in larger particle sizes and a lower unsaturated defect rate. Conversely, if the concentration of zirconium salt is too high, it will result in waste of raw materials.

[0086] Because the synthesis of organometallic compounds (MMCs) involves multiple steps and is influenced by various parameters, even minute changes in synthesis conditions can have multidimensional effects on the actual microscopic reaction environment, thereby affecting the structure of the MMC. For example, reducing the amount of template agent decreases the solubility of the dicarboxylated conjugated organic ligand, i.e., reduces the actual solution concentration of the dicarboxylated conjugated organic ligand. Simultaneously, the ratio of template agent to dicarboxylated conjugated organic ligand undergoes a non-linear change, reducing the template agent's ability to coat the initial zirconium-oxygen clusters. These three parameters all affect the nucleation and growth of MMCs at different stages, and the mechanisms are unclear. Similarly, the zirconium salt concentration, or the ratio of zirconium salt to template agent, or the solvent type or reaction temperature all affect the product's molecular formula and unsaturated coordination defect rate, and these effects are difficult to predict.

[0087] In some embodiments of this application, the molar ratio of the zirconium salt to the dicarboxylated conjugated organic ligand is 1:(0.6~2). For example, the molar ratio of the zirconium salt to the dicarboxylated conjugated organic ligand can be 1:0.6, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, or a range consisting of any two of these values. Controlling the molar ratio of the zirconium salt to the dicarboxylated conjugated organic ligand within the range specified in this application is beneficial for controlling the nucleation and growth rate of the metal-organic complex, thereby increasing the unsaturated coordination defect rate and the total defect rate in the metal-organic complex structure.

[0088] In some embodiments of this application, the molar ratio of the zirconium salt to the template agent is (0.02~0.3):1. For example, the molar ratio of the zirconium salt to the template agent can be 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, or a range of any two of these values. By controlling the molar ratio of the zirconium salt to the template agent within the range of this application, taking glacial acetic acid as the template agent as an example, during the synthesis of the organometallic complex, the template agent first competitively reacts with the zirconium salt with a dicarboxyl conjugated organic ligand, forming Zr6O4(OH)4(HAc)6 clusters in situ. These clusters then further react with the dicarboxyl conjugated organic ligand, promoting the growth of the framework structure through a condensation process. It is noteworthy that a high concentration of template agent has an inhibitory effect on crystal growth, which helps to form organometallic complexes with larger grain size, higher crystallinity, and lower defect characteristics. When the template agent concentration is too high, there are two effects. First, too much template agent will inhibit the growth of metal-organic complexes and reduce the unsaturated coordination defect rate. Growth is inhibited because too much template agent will make it difficult for OLs to be replaced to growth sites. Second, the template agent will occupy unsaturated coordination sites, resulting in a decrease in the unsaturated coordination defect rate.

[0089] In some embodiments of this application, the reaction system is mechanically stirred at a rate of 400–800 r / min. For example, the stirring rate may be 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, or a range of any two of these values. The stirring rate has a significant impact on particle size but a relatively small impact on the molecular formula and unsaturated defect rate. Controlling the stirring rate within the range specified in this application helps to form metal-organic composites with smaller particle sizes. Higher stirring rates result in more nucleation sites and smaller crystal sizes compared to lower stirring rates. However, there is a limit to the size reduction; excessively high stirring rates only increase energy consumption, while excessively low stirring rates lead to larger metal-organic composite particle sizes. In some embodiments of this application, the reaction system is mechanically stirred and simultaneously heated at a temperature of 60°C–120°C for 1 h–168 h, followed by solid-liquid separation to obtain a crude metal-organic composite product. For example, the heating temperature can be 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, or a range of any two of these values; the heating time can be 1h, 10h, 30h, 50h, 80h, 100h, 120h, 150h, 168h, or a range of any two of these values. By adjusting the heating temperature and time within the range specified in this application, the nucleation process and growth rate of the metal-organic composite can be effectively controlled, while also affecting the degree of substitution of the dicarboxylic acid conjugated organic ligands. This precise control strategy can promote the metal-organic composite to exhibit a higher total defect rate and unsaturated coordination defect rate, which has a positive impact on improving the material's performance and functionality.

[0090] In some embodiments of this application, the crude product of the organometallic complex is washed and separated to obtain the organometallic complex. Specifically, the crude product of the organometallic complex is soaked and washed with a low-boiling-point solvent, the number of soaking and washing cycles being 3 to 8, and the soaking time for each cycle being 6 to 24 hours; the low-boiling-point solvent is selected from at least one of methanol, ethanol, tetrahydrofuran, acetone, dichloromethane, and chloroform. For example, the number of soaking and washing cycles can be 3, 5, 6, or 8, or any combination of two of these values; the soaking time for each cycle can be 6 hours, 9 hours, 12 hours, 15 hours, 18 hours, 21 hours, or 24 hours, or any combination of two of these values. For example, the soaking process can use ethanol for 12 hours, acetone for 12 hours, dichloromethane for 12 hours, then ethanol for 12 hours, acetone for 12 hours, and dichloromethane for 12 hours, for a total of 6 soakings using different liquids. Soaking the crude metal-organic complex product in the low-boiling-point solvent described in this application is beneficial for removing residual unreacted reactants and template agents from the crude metal-organic complex product; using the number of soaking times and soaking time within the scope of this application is beneficial for improving the cleaning effect of residual unreacted reactants and template agents from the crude metal-organic complex product.

[0091] In some embodiments of this application, a drying step is included after the separation step described in step (3).

[0092] Example:

[0093] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0094] Test methods and equipment:

[0095] Thermogravimetric analysis for determining the total defect rate of organometallic compounds:

[0096] Thermogravimetric analysis (TGA) was used to test the defect rate of the metal-organic composite. The test temperature range was 50℃-600℃, the heating rate was 3℃ / min, and the test atmosphere was air.

[0097] The results were processed as follows: The mass of the remaining material (zirconia) from the TGA test at 600℃ was used as the baseline, and normalization was performed, recorded as 100%. Under ideal conditions, in a defect-free perfect crystal, the chemical formula of the organometallic compound at 350°C is Zr6O6(OL)6, and the corresponding normalized weight is N (%). ×100%, where M(Zr6O6(OL)6) represents the molar mass of Zr6O6(OL)6, and M(ZrO2) represents the molar mass of ZrO2. At 350°C, the normalized weight of the defective organometallic complex is lower than N (%), indicating insufficient OL linkers within the defective organometallic complex. The total defect rate is calculated using the formula: Where w% (350℃) is the standardized weight of the metal-organic compound containing defects at 350℃, i.e., w% (350℃) = weight of the remaining material at a test temperature of 350℃ / weight of the remaining material at a test temperature of 600℃ × 100%, and Z is the total defect rate of the metal-organic compound.

[0098] Solid-state NMR phosphorus spectroscopy for determining the unsaturated coordination defect rate of organometallic complexes:

[0099] The unsaturated coordination defect rate of the organometallic complex (MMC) was determined using solid-state NMR phosphorus spectrometry: The MMC was activated under vacuum at 150 °C for 4 h. 100 mg of 2,2,6,6-tetramethylpiperidine-1-oxo radical (TMPO) was dissolved in 15 mL of dichloromethane to obtain a TMPO solution. 50 mg of the activated MMC was added to the TMPO solution and immersed for 1 h. Defects in the MMC were labeled and identified using TMPO. The total defect rate and unsaturated coordination defect rate of the MMC were measured using an NMR spectrometer (Bruker Avance NEO 600 MHz, Germany). A 3.2 mm MAS probe was used, with a rotation speed of 15 or 18 kHz. 31 The P signal is calibrated using the NH4H2PO4 signal.

[0100] Origin software was used to perform peak fitting on the data between 1 and 100, and the R-squared value of the fitted curve was obtained. 2 >99.7. Quantitative analysis was performed based on peak area, with peaks above 50° considered to correspond to Lewis acid sites at the nodes. Peaks with chemical shifts around 62, 58, 55, and 53° were identified as Zr-blank, μ-OH(OL), μ-OH(sol), and Zr-sol sites, respectively. Zr-blank represents unsaturated coordination defects, μ-OH(OL) represents bridged hydroxyl groups adjacent to organic ligands, μ-OH(sol) represents bridged hydroxyl groups adjacent to small organic molecule coordination, and Zr-sol represents coordination defects in small organic molecule coordination.

[0101] Taking the test results of Example 3 as an example, the test results are as follows: Figure 6As shown, the black dots represent the original test data, and the solid line represents the fitted data. The arrow pointing to μ-OH(OL) indicates that the area of ​​the peak formed by this curve is based on the total number of Zr-blank, μ-OH(OL), μ-OH(sol), and Zr-sol sites, with the percentage of μ-OH(OL) sites. The arrow pointing to Zr-blank indicates that the area of ​​the peak formed by this curve is based on the total number of Zr-blank, μ-OH(OL), μ-OH(sol), and Zr-sol sites, with the percentage of Zr-blank sites. The arrow pointing to Zr-sol indicates that the area of ​​the peak formed by this curve is based on the total number of Zr-blank, μ-OH(OL), μ-OH(sol), and Zr-sol sites, with the percentage of Zr-sol sites. Origin software was used to analyze the data. Figure 6 The data in Table 1 was obtained through analysis.

[0102] Table 1. Area percentage and total defect rate of each point in the metal-organic composite of Example 3:

[0103]

[0104] Wherein, the value corresponding to Zr-blank is the unsaturated coordination defect rate, denoted as K; the sum of the values ​​corresponding to Zr-blank, μ-OH(sol), and Zr-sol is the total defect rate, denoted as S.

[0105] Organometallic compound with molecular formula Zr6O m (OH) n (OL) 6-(x+y) / 2 (sol) x (blank) y N b In (4≤m≤6, 0≤n≤4, 0.9≤b≤6.94), x=12(SK), y=12K.

[0106] Reliability analysis of unsaturated coordination defect rate of samples using solid-state phosphorus NMR spectroscopy:

[0107] The ratio of OL to sol in the organometallic complex of Example 37 was determined using liquid NMR, and the specific procedure is as follows:

[0108] Sample pretreatment: The sample was vacuum dried at 120℃ for 12 h to remove small molecules physically adsorbed within the pores. Then, 25 mg of the sample was placed in 5 mL of NaOH deuterium aqueous solution (1 mol / L) and sonicated for 1 h. After complete decomposition, the sample was filtered, and the liquid NMR spectrum (H1N1) was measured using a Bruker Ascend 400 spectrometer. The ratio P of OL to sol was obtained from the integral of the liquid NMR spectrum.

[0109] As mentioned above, the total defect rate Z can be obtained using thermogravimetric analysis. In the molecular formula, OL is subscripted as 6 - (x + y) / 2 = 6 × (1 - Z). Based on the liquid NMR results, the ratio P of OL to sol can be obtained: P = [6 - (x + y) / 2] / x. Therefore, x = 6 × (1 - Z) / P; y = 12Z - 6 × (1 - Z) / P.

[0110] The unsaturated coordination defect rate is K = y / 12 = Z - (1-Z) / 2P, the defect rate for other types is x / 12 = (1-Z) / 2P, and the total defect rate is Z. The test results are shown in Table 2.

[0111] Table 2. Defect rates of the metal-organic composite in Example 37 measured by different test methods:

[0112]

[0113] Test of the molar ratio of Zr to OL in organometallic compounds:

[0114] Zr concentration test: Approximately 0.1 g of sample + 4 mL concentrated sulfuric acid + 1 mL hydrogen peroxide were heated at 130℃ for 1 hour using an electric heater. After cooling to room temperature, microwave digestion was performed (microwave digestion program: 120℃-3 min; 150℃-3 min; 180℃-3 min; 200℃-10 min; 220℃-15 min). After digestion, the sample was cooled to room temperature, and the cap and body of the volumetric flask were rinsed at least three times with ultrapure water. The volume was then adjusted to 50 mL. The Zr molar concentration C(Zr) was obtained by measuring the solution using inductively coupled plasma atomic emission spectrometry.

[0115] OL Concentration Test: Accurately weigh approximately 100 mg of sample and add 10 mL of 5 mol / L H₂SO₄ aqueous solution. Sonicate in a 60°C water bath for 30 min until the solution is clear. Transfer the entire solution to a 25 mL volumetric flask and dilute to the mark with ultrapure water. Take 0.5 mL of the sample solution, dilute 20 times, and filter through a 0.22 μm filter to measure the absorbance. Use liquid chromatography (HPLC) to determine the concentration. The instrument model is Agilent ZORBAX SB-C18. The mobile phase elution program is a gradient elution of 85% acetonitrile and 15% formic acid aqueous solution (0.1%), with a run time of 12 minutes. The OL concentration C(OL) can be obtained.

[0116] The molar ratio of Zr to OL is C(Zr) / C(OL).

[0117] Average particle size test of organometallic compounds:

[0118] 2 mg of organometallic compound was dispersed in 20 mL of methanol and sonicated for 20-60 min. A portion of the suspension was then dropped onto a copper grid and dried. The average particle size of the sample was measured using a transmission electron microscope (TEM) at a magnification of 1 million times. The particle size of the organometallic compound particles in the TEM image was measured using Processing-Velox software, and the average particle size was obtained by Gaussian fitting.

[0119] Test of the types and quantities of counterions within a single unit cell:

[0120] 25 mg of the organometallic compound was added to 5 mL of 1 mol / L NaOH solution to obtain the test solution. The types and concentrations (mass fractions) of counterions in the test solution were determined using an ion chromatograph (Dionex-7680). The mass fraction of counterions in the test solution was calculated to be W(N), and the molar mass of the counterions was calculated to be M(N). The mass fraction of Zr in the test solution was determined by ICP (inductively coupled plasma atomic emission spectrometry) to be W(Zr), where the molar mass of Zr is M(Zr).

[0121] The molecular formula of the organometallic compound is Zr6O4(OH)4(OL). 6-(x+y) / 2 (sol) x (blank) y N b In this context, the value of b is calculated using the mass fraction of the counter ions mentioned above.

[0122] Test of the types of functional groups X:

[0123] The types of functional group X in organometallic compounds were determined using a Fourier transform infrared spectroscopy (IS50) instrument. Background acquisition (using air as the background) was performed first. Then, a small amount of powder sample was placed on a KBr crystal, ensuring the powder covered the crystal. The pressure column was then rotated clockwise to compress the sample. The sample was then tested, with 32 scans and a data interval of 1.928 cm⁻¹. -1 Save the results after collection is complete.

[0124] Carbon dioxide adsorption rate test:

[0125] The organometallic composite was vacuum-dried at 120°C for 24 hours to remove physically adsorbed gases (such as N2 and H2O from the air) within the pores. Before testing, all samples were degassed at 473 K for 3 hours and then vacuum-treated for 240 minutes before analysis. Carbon dioxide adsorption isotherms were collected using an automated adsorption isotherm analyzer (Mike, TriStar II Plus). The specific procedure was as follows: 0.1 g of sample was placed in the sample holder, immersed in a 25°C deionized water constant temperature bath, and the carbon dioxide pressure was controlled at 100 MPa. After 1 hour of carbon dioxide adsorption, the adsorption isotherm curve was measured to obtain the amount of carbon dioxide adsorbed.

[0126] Example 1:

[0127] 38.5 g (154.5 mmol) of hydrated zirconium nitrate and 19.6 g (108 mmol) of 2-aminoterephthalic acid were added to a 1000 mL two-necked flask, followed by 256.54 mL of deionized water and 29.46 mL of glacial acetic acid to obtain the reaction system.

[0128] The reaction system was mechanically stirred at a rate of 600 r / min. Simultaneously, the reaction system was heated to 100℃ for 24 hours. Subsequently, the crude metal-organic complex was obtained by centrifugation at 10000 r / min for 10 min.

[0129] The crude product of the organometallic complex was washed using the following steps: soaking in ethanol for 12 h, soaking in acetone for 12 h, soaking in dichloromethane for 12 h, then soaking in ethanol for 12 h, soaking in acetone for 12 h, and then soaking in dichloromethane for 12 h, for a total of 6 soakings with different liquids. After each soaking, the supernatant was separated by centrifugation, and then fresh solvent was added. The centrifugation rate was 10000 r / min, and the centrifugation time was 15 min to obtain the organometallic complex.

[0130] Carbon dioxide was adsorbed using organometallic compounds, and the adsorption rates are shown in Table 4.

[0131] Based on the volume of the reaction system, the molar concentration of zirconium salt is 540 mmol / L, the molar ratio of zirconium salt to dicarboxylic acid conjugated organic ligand is 1:0.7, and the molar ratio of zirconium salt to template agent is 0.3:1.

[0132] Thermogravimetric analysis showed that the total defect rate of the organometallic compound was 53.5%; solid-state NMR phosphorus spectroscopy showed that the unsaturated coordination defect rate was 50.1%; and the average particle size of the organometallic compound was 24 nm.

[0133] Examples 2 to 38:

[0134] Except for adjusting the types, contents, and preparation parameters of zirconium salt, dicarboxylic acid conjugated organic ligand, and template agent according to Tables 3 and 4, the rest is the same as in Example 1. The total volume of deionized water and template agent added is controlled to be 286 mL.

[0135] In Example 31, sol consists of formate and acetate ions, with a total amount of formate and acetate ions in each molecule of 0.468 (x=0.468).

[0136] Comparative Example 1:

[0137] 0.385 g (1.545 mmol) of hydrated zirconium oxynitrate and 0.54 g (3 mmol) of 2-aminoterephthalic acid were added to a 1000 mL two-necked flask, followed by 6 mL of deionized water and 280 mL of glacial acetic acid to obtain the reaction system.

[0138] Take 100 mL of the reaction solution, transfer the reaction system into a 200 mL Teflon liner, and place it in an oven to heat.

[0139] The heating temperature was 120 °C and the heating time was 168 hours; then the crude product of the organometallic complex was obtained by centrifugation at 10000 r / min for 10 min.

[0140] The crude product of the organometallic compound was washed, and the specific steps were the same as in Example 1, to obtain the organometallic compound.

[0141] Table 3 shows the particle size of the organometallic compounds, the total defect rate of the organometallic compounds measured by thermogravimetric analysis, and the unsaturated coordination defect rate of the organometallic compounds measured by solid-state NMR phosphorus spectroscopy. Table 4 shows the carbon dioxide adsorption rate achieved using organometallic compounds.

[0142] Based on the volume of the reaction system, the molar concentration of zirconium salt is 5.4 mmol / L, the molar ratio of zirconium salt to organic ligand is 1:2, and the molar ratio of zirconium salt to template agent is 0.0003:1.

[0143] Comparative Example 2:

[0144] 0.385 g (1.545 mmol) of hydrated zirconium oxynitrate and 0.54 g (3 mmol) of 2-aminoterephthalic acid were added to a 1000 mL two-necked flask, followed by 6 mL of deionized water and 280 mL of glacial acetic acid to obtain the reaction system.

[0145] The reaction system was mechanically stirred at a rate of 600 r / min. Simultaneously, the reaction system was heated to 120 °C for 168 hours. The crude metal-organic complex was then separated by centrifugation at 10000 r / min for 10 min.

[0146] The crude product of the organometallic compound was washed, and the specific steps were the same as in Example 1, to obtain the organometallic compound.

[0147] Table 3 shows the particle size of the organometallic compounds, the total defect rate of the organometallic compounds measured by thermogravimetric analysis, and the unsaturated coordination defect rate of the organometallic compounds measured by solid-state NMR phosphorus spectroscopy. Table 4 shows the carbon dioxide adsorption rate achieved using organometallic compounds.

[0148] Based on the volume of the reaction system, the molar concentration of zirconium salt is 5.4 mmol / L, the molar ratio of zirconium salt to organic ligand is 1:2, and the molar ratio of zirconium salt to template agent is 0.0003:1.

[0149] Comparative Example 3:

[0150] Carbon dioxide adsorption was performed using commercially available organometallic composite materials (Innochem, CAS No.: 1260119-00-3, Product No.: A63394). The carbon dioxide adsorption rate is shown in Table 4.

[0151] Comparative Example 4:

[0152] Except for adjusting the types, contents, and preparation parameters of zirconium salt, dicarboxylic acid conjugated organic ligand, and template agent according to Table 4, the rest is the same as in Example 1. The total volume of deionized water and template agent added is controlled to be 286 mL.

[0153] Table 3:

[0154]

[0155] Note: In Table 3, " / " indicates that the corresponding preparation parameters or substances do not exist.

[0156] Table 4:

[0157]

[0158] Note: In Table 4, " / " indicates that the corresponding preparation parameter or substance does not exist; "D" represents the molar concentration of zirconium salt in mmol / L; "S" represents the molar ratio of zirconium salt to dicarboxylic acid conjugated organic ligand; "K" represents the unsaturated coordination defect rate obtained by solid-state NMR phosphorus spectroscopy in %; "Z" represents the total defect rate obtained by thermogravimetric analysis in %; and "Q" represents the carbon dioxide adsorption rate in %.

[0159] As can be seen from Examples 1 to 38, the organometallic composites of each embodiment of this application have high unsaturated coordination defects and high carbon dioxide adsorption rates; while the organometallic composites of Comparative Examples 1 and 2 have low unsaturated coordination defect rates and low carbon dioxide adsorption rates; Comparative Example 3 is a commercially available organometallic composite material, which, according to testing, has a low unsaturated coordination defect rate and a low carbon dioxide adsorption rate. As can be seen from Examples 1 to 4 and Example 37, the molecular formula of the organometallic composite is within the scope of this application, and the organometallic composite has a high unsaturated coordination defect rate, small particle size, and high carbon dioxide adsorption rate. The molecular formula of the organometallic composite of Comparative Example 4 is outside the scope of this application. Although the unsaturated coordination defect rate and total defect rate are increased, its internal structural collapse results in a low carbon dioxide adsorption rate.

[0160] The type of molecular framework and functional group X can affect the chemical properties of organometallic compounds, thereby affecting the unsaturated coordination defect rate, total defect rate, and particle size of the organometallic compounds. As can be seen from Examples 6 to 15 and Example 38, within the scope of this application, the types of molecular framework and functional group X result in organometallic compounds with higher unsaturated coordination defect rates, smaller particle sizes, and higher carbon dioxide adsorption rates.

[0161] As can be seen from Examples 5, 16 to 24, the types of zirconium salts are within the scope of this application, and the resulting organometallic composites exhibit higher unsaturated coordination defect rates, smaller particle sizes, and higher carbon dioxide adsorption rates. As can be seen from Examples 25 to 37, the types of template agents, heating temperatures, heating times, zirconium salt molar concentrations, and the molar ratio of zirconium salt to organic ligands are within the scope of this application, and the resulting organometallic composites exhibit higher saturated coordination defect rates, smaller particle sizes, and higher carbon dioxide adsorption rates.

[0162] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A metal-organic composite, characterized in that, The organometallic compound has the molecular formula Zr6O. m (OH) n (OL) 6-(x+y) / 2 (sol) x (blank) y N b , 4≤m≤6, 0≤n≤4, 0.09≤x≤0.92, 3≤y≤6.02, 0.9≤b≤6.94; wherein, OL is a dicarboxylic acid conjugated organic ligand, the dicarboxylic acid conjugated organic ligand comprising a molecular skeleton, the molecular skeleton comprising any one of phenyl, pyridinyl and imidazole groups, and sol comprises acetate, formate and CH3(CH2). p COO - At least one of the following, 1≤p≤6, blank is a ligand vacancy, and N is a counter ion.

2. The organometallic compound according to claim 1, characterized in that, In the organometallic compound, the molar ratio of Zr to OL is 6:(2.766~4.266).

3. The organometallic compound according to claim 1, characterized in that, In the organometallic compound, the molar ratio of Zr to OL is 6:(2.766~3.996).

4. The organometallic compound according to claim 1, characterized in that, In the organometallic complex, the molar ratio of Zr to OL is 6:(2.766~3.51).

5. The organometallic compound according to claim 1, characterized in that, In the organometallic compound, the molar ratio of Zr to OL is 6:(2.766~3.44).

6. The organometallic compound according to claim 1, characterized in that, In the organometallic compound, the molar ratio of Zr to OL is 6:(2.766~2.928).

7. The organometallic compound according to claim 1, characterized in that, The organometallic complex comprises a cationic framework and an in-pore adsorbed component.

8. The organometallic compound according to claim 1, characterized in that, When the molecular skeleton is phenyl, the dicarboxylic acid conjugated organic ligand includes at least one of terephthalate, isophthalate and phthalate.

9. The organometallic compound according to claim 1, characterized in that, When the molecular skeleton is phenyl, the dicarboxylated conjugated organic ligand includes functional group X, which includes any one of amino, hydroxyl, mercapto, methoxy, nitro, fluorine, and chlorine groups.

10. The organometallic compound according to claim 9, characterized in that, The dicarboxylated conjugated organic ligand includes at least one of the following substances: (1) When the functional group X is an amino group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-aminoterephthalate, 2,5-diaminoterephthalate, 2,3-diaminoterephthalate, 2,3,5-triaminoterephthalate and 2,3,4,5-tetraaminoterephthalate. (2) When the functional group X is a hydroxyl group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-hydroxyterephthalate, 2,5-dihydroxyterephthalate, 2,3-dihydroxyterephthalate, 2,3,5-trihydroxyterephthalate and 2,3,4,5-tetrahydroxyterephthalate; (3) When the functional group X is a thiol group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-mercaptoterephthalate, 2,5-dimercaptoterephthalate, 2,3-dimercaptoterephthalate, 2,3,5-trimercaptoterephthalate and 2,3,4,5-tetramercaptoterephthalate; (4) When the functional group X is methoxy, the dicarboxylic acid conjugated organic ligand includes at least one of 2-methoxyterephthalate, 2,5-dimethoxyterephthalate, 2,3-dimethoxyterephthalate, 2,3,5-trimethoxyterephthalate and 2,3,4,5-tetramethoxyterephthalate; (5) When the functional group X is a nitro group, the dicarboxylic acid conjugated organic ligand includes at least one of 2-nitroterephthalate, 2,5-dinitroterephthalate, 2,3-dinitroterephthalate, 2,3,5-trinitroterephthalate and 2,3,4,5-tetranitroterephthalate; (6) When the functional group X is a fluorine group, the dicarboxylic acid conjugated organic ligand includes at least one of 2,5-dicarboxyfluorobenzoate, 2,5-difluoroterephthalate, 2,3-difluoroterephthalate, 2,3,5-trifluoroterephthalate and 2,3,4,5-tetrafluoroterephthalate; (7) When the functional group X is a chlorine group, the dicarboxylic conjugated organic ligand includes at least one of 2,5-dicarboxychlorophthalate, 2,5-dichloroterephthalate, 2,3-dichloroterephthalate, 2,3,5-trichloroterephthalate and 2,3,4,5-tetrachloroterephthalate.

11. The organometallic compound according to claim 1, characterized in that, The molecular skeleton is selected from either pyridyl or imidazolyl, and the dicarboxylated conjugated organic ligand includes at least one of the following substances: (1) When the molecular skeleton is selected from pyridinyl, the dicarboxylic acid conjugated organic ligand includes 2,5-pyridinic acid dicarboxylate; (2) When the molecular skeleton is selected from imidazole, the dicarboxylic conjugated organic ligand includes at least one of 1H-imidazol-2,4-dicarboxylate and imidazol-4,5-dicarboxylate.

12. The organometallic compound according to claim 1, characterized in that, The counterions include NO3. - Cl - SO4 2- ,Br - acetylacetone and F - At least one of them.

13. The organometallic compound according to any one of claims 1 to 12, characterized in that, The unsaturated coordination defect rate of the organometallic complex was found to be 25% to 50.1% by solid-state NMR phosphorus spectroscopy.

14. The organometallic compound according to claim 13, characterized in that, The unsaturated coordination defect rate of the organometallic compound is 26.1% to 50.1%.

15. The organometallic compound according to claim 13, characterized in that, The unsaturated coordination defect rate of the organometallic complex is 30.7% to 50.1%.

16. The organometallic compound according to claim 13, characterized in that, The unsaturated coordination defect rate of the metal-organic complex is 37%~50.1%.

17. The organometallic compound according to claim 13, characterized in that, The unsaturated coordination defect rate of the organometallic compound is 40.7%~50.1%.

18. The organometallic compound according to claim 13, characterized in that, The unsaturated coordination defect rate of the organometallic compound is 43%~50.1%.

19. The organometallic compound according to claim 13, characterized in that, The unsaturated coordination defect rate of the organometallic complex is 47.5%~50.1%.

20. The organometallic compound according to any one of claims 1 to 12, characterized in that, The total defect rate of the metal-organic composite was found to be 29.6%–53.5% by thermogravimetric analysis.

21. The organometallic compound according to claim 20, characterized in that, The total defect rate of the metal-organic complex is 32.9% to 53.5%.

22. The organometallic compound according to claim 20, characterized in that, The total defect rate of the metal-organic complex is 37.5% to 53.5%.

23. The organometallic compound according to claim 20, characterized in that, The total defect rate of the metal-organic complex is 41% to 53.5%.

24. The organometallic compound according to claim 20, characterized in that, The total defect rate of the metal-organic complex is 45% to 53.5%.

25. The organometallic compound according to claim 20, characterized in that, The total defect rate of the metal-organic complex is 50.9% to 53.5%.

26. The organometallic compound according to any one of claims 1 to 12, characterized in that, The average particle size of the metal-organic composite is 15 nm to 125 nm.

27. A method for preparing a metal-organic composite, characterized in that, Includes the following steps: (1) A reaction system is obtained by adding zirconium salt and dicarboxylic acid conjugated organic ligand to a mixed solution of deionized water and template agent; wherein the reaction system is a suspension system, and the molar concentration of zirconium salt is 300 mmol / L to 600 mmol / L based on the volume of the reaction system; the molar ratio of zirconium salt to dicarboxylic acid conjugated organic ligand is 1:(0.6~2), and the molar ratio of zirconium salt to template agent is (0.02~0.3):1; (2) The reaction system is mechanically stirred and heated at a temperature of 60°C to 120°C for a time of 1 h to 168 h. The crude product of the metal-organic complex is obtained by solid-liquid separation. (3) The crude product of the organometallic compound is washed and separated to obtain the organometallic compound; The organometallic compound has the molecular formula Zr6O. m (OH) n (OL) 6-(x+y) / 2 (sol) x (blank) y N b , 4≤m≤6, 0≤n≤4, 0.09≤x≤0.92, 3≤y≤6.02, 0.9≤b≤6.94; wherein, OL is a dicarboxylic acid conjugated organic ligand, the dicarboxylic acid conjugated organic ligand includes a molecular skeleton, the molecular skeleton includes any one of phenyl, pyridinyl and imidazole groups, and sol includes acetate, formate, CH3(CH2) p COO - At least one of the following, 1≤p≤6, blank is a ligand vacancy, and N is a counter ion.

28. The preparation method according to claim 27, characterized in that, The zirconium salt includes at least one selected from zirconium oxynitrate, zirconium chloride, zirconium oxychloride, zirconium bromide, zirconium fluoride, zirconium acetylacetonate, and zirconium sulfate; the template agent includes glacial acetic acid, formic acid, and CH3(CH2). p At least one of COOH, 1≤p≤6.

29. The preparation method according to claim 27, characterized in that, Step (3) includes a drying step after the separation step.

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