A tetrazolyl hydrogen-bonded organic framework material and its preparation method and application

Abstract

The present invention relates to a tetrazole-based hydrogen-bonded organic framework material and its preparation method and application, belonging to the technical field of functional organic crystalline materials. The tetrazole-based hydrogen-bonded organic framework material of the present invention is assembled by monomer molecules and solvent molecules through hydrogen bonding, and has a three-dimensional structure. The four tetrazole functional groups of each monomer molecule are connected to the solvent molecules through N-H...O hydrogen bonds. Adjacent monomer molecules are stacked to form a three-dimensional hydrogen-bonded organic framework through the synergistic effect of π-π stacking between tetrazole rings and benzene rings. The hydrogen-bonded organic framework has one-dimensional continuous channels, and the channels are filled with guest molecules. The tetrazole-based hydrogen-bonded organic framework material disclosed by the present invention can be used for selective static adsorption of p-xylene in a variety of xylene mixtures.

Description

Technical Field

[0001] The present invention relates to the technical field of functional organic crystalline materials, and in particular to a tetrazole-based hydrogen-bonded organic framework material and a preparation method and application thereof. Background Art

[0002] Xylenes are important organic chemical raw materials. Para-xylene, the most valuable isomer, is the primary feedstock for the production of terephthalic acid (PET), which is widely used in the production of polyester plastics such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBTE). With the development of my country's polyester industry, demand for para-xylene is increasing. The efficient and cost-effective separation of para-xylene from industrially produced C8 aromatics mixtures (industrially, a mixture of aromatic hydrocarbons containing eight carbon atoms, primarily o-xylene, p-xylene, m-xylene, ethylbenzene, and sometimes styrene, from various sources) is crucial to the sustainable development of the chemical industry.

[0003] However, xylene isomers have very similar structures and physicochemical properties, making them difficult to separate by distillation. Currently, most paraxylene is obtained through adsorption separation methods based on simulated moving beds, which have limited adsorption capacity and selectivity and require high temperature and high pressure operation. Developing adsorbents with high adsorption capacity and selectivity that can separate paraxylene from liquid C8 aromatics mixtures at ambient temperature and pressure could significantly reduce energy consumption and costs in the xylene separation process, and has broad application prospects.

[0004] Hydrogen-bonded organic frameworks (HOFs) are a class of crystalline, porous framework materials composed of organic or metal-organic building blocks connected by hydrogen bonds. They offer advantages such as low density, high specific surface area, high crystallinity, solution processability, and simple preparation and regeneration. They hold broad application prospects in gas separation and storage, isomer separation, molecular recognition, proton conduction, and biomedicine. However, due to the weak and poorly directional nature of hydrogen bonds, their organic building blocks tend to pack closely during crystallization. Controlling the hydrogen-bonded self-assembly of these building blocks to crystallize into crystalline porous materials rather than dense, non-porous crystals remains a major challenge.

[0005] At present, although the existing technology discloses that metal-organic framework materials can be used to separate para-xylene from C8 aromatic hydrocarbon mixtures, metal-organic framework materials have the problems of complex preparation, poor renewability, and high requirements for separation conditions, and the separation effect of para-xylene / ethylbenzene still needs to be improved. Summary of the Invention

[0006] In view of the above analysis, the present invention aims to provide a tetrazolyl-based hydrogen-bonded organic framework material and its preparation method and application, so as to solve at least one of the problems of existing metal-organic framework materials, such as complex preparation, high conditions for separating paraxylene, and poor separation effect of ethylbenzene.

[0007] In a first aspect, the present invention provides a tetrazolyl hydrogen-bonded organic framework material, the molecular formula of the tetrazolyl hydrogen-bonded organic framework material is as follows:

[0008] [(C 29 H 20 N 16 ) a (C3H7NO) b (G) c ] n , wherein a, b, and c are all positive integers, n is the number of crystal repeating units, and G is the molecular formula of the guest molecule, wherein the guest molecule includes but is not limited to one or more of 1,4-dioxane, p-xylene, m-xylene, o-xylene, mesitylene, 1,2,4-trichlorobenzene, methyl benzoate, toluene, N,N'-dimethylformamide, etc.

[0009] Furthermore, the tetrazolyl hydrogen bond organic framework material belongs to the orthorhombic system, the space group is Pbcn or Cmcm, and the unit cell parameter is α=β=γ=90°;

[0010] And / or, the tetrazolyl hydrogen bond organic framework material belongs to the orthorhombic crystal system, the space group is Pccn, and the unit cell parameter is α=β=γ=90°;

[0011] And / or, the tetrazolyl hydrogen bond organic framework material belongs to the orthorhombic crystal system, the space group is Pbca, and the unit cell parameter is α=β=γ=90°.

[0012] Furthermore, the tetrazolyl hydrogen-bonded organic framework material comprises one-dimensional continuous channels, and the one-dimensional continuous channels extend along the

[010] or

[001] crystal plane direction;

[0013] Preferably, the size of the one-dimensional continuous channel is p×m, wherein,

[0014] Preferably, the porosity of the tetrazolyl hydrogen-bonded organic framework material is 16.1 to 32.5%.

[0015] In a second aspect, the present invention provides a method for preparing the above-mentioned tetrazolyl hydrogen-bonded organic framework material, comprising the following steps:

[0016] (1) dissolving tetrakis(4-2H-tetrazol-5-ylphenyl)methane in an organic solvent and filtering to obtain a clear tetrakis(4-2H-tetrazol-5-ylphenyl)methane solution;

[0017] (2) The tetrakis(4-2H-tetrazolyl-5-phenyl)methane clarified solution and guest molecules are subjected to a gas phase diffusion method or a liquid phase diffusion method to obtain the tetrazolyl-based hydrogen bond organic framework material.

[0018] Furthermore, in step (1), the organic solvent is N,N'-dimethylformamide;

[0019] And / or, the concentration of the tetrakis(4-2H-tetrazol-5-ylphenyl)methane in the organic solvent is 16-24 mg / mL.

[0020] Furthermore, in step (2), the volume ratio of the guest molecule to the organic solvent is ≥2.

[0021] Furthermore, in step (2), the vapor diffusion method is specifically as follows: placing the tetrakis(4-2H-tetrazolyl-5-phenyl)methane clarified solution in an uncovered device, and then placing the uncovered device in a covered device containing guest molecules, performing constant temperature diffusion crystallization to obtain the tetrazolyl hydrogen bonded organic framework material.

[0022] Furthermore, in step (2), the liquid phase diffusion method is specifically as follows: placing the tetrakis(4-2H-tetrazolyl-5-phenyl)methane clear solution in a container, then slowly spreading the guest molecules on the surface of the tetrakis(4-2H-tetrazolyl-5-phenyl)methane clear solution, sealing the container, and diffusion crystallizing at room temperature to obtain the tetrazolyl hydrogen bonded organic framework material.

[0023] In a third aspect, the present invention provides an activation material for separating paraxylene, wherein the activation material is prepared by the following method: removing guest molecules from the above-mentioned tetrazolyl hydrogen bond organic framework material by a solvent exchange method, and vacuum activation to obtain the activation material.

[0024] In a fourth aspect, the present invention provides an application of the above-mentioned tetrazolyl hydrogen-bonding organic framework material in the static adsorption of p-xylene or the separation of p-xylene from a mixture.

[0025] Furthermore, the application includes the following steps:

[0026] (a) removing guest molecules from a tetrazole-based hydrogen-bonded organic framework material by a solvent exchange method, and vacuum-activating the material to obtain an activated material;

[0027] (b) soaking the activated material in a C8 aromatic hydrocarbon mixture, centrifuging, removing the supernatant, washing, and drying to obtain a tetrazolyl hydrogen-bonded organic framework material that adsorbs p-xylene.

[0028] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0029] (1) The tetrazolyl hydrogen bond organic framework material of the present invention is assembled by monomer molecules and solvent molecules through hydrogen bonding, and has a three-dimensional structure. The molecular formula is [(C 29 H 20 N 16 ) a (C3H7NO) b (G) c ] n The four tetrazole functional groups of each monomer molecule are connected to the solvent molecules through NH…O hydrogen bonds. Adjacent monomer molecules are stacked through the synergistic effect of π-π stacking between the tetrazole ring and the benzene ring to form a three-dimensional hydrogen-bonded organic framework. The hydrogen-bonded organic framework has one-dimensional continuous channels, which are filled with guest molecules.

[0030] (2) The method for preparing tetrazolyl hydrogen-bonded organic framework materials of the present invention is characterized by utilizing a guest-induced template method to achieve the assembly of porous hydrogen-bonded organic framework materials, thereby avoiding the close packing of organic building units during the crystallization process, and achieving a porosity of up to 32.5%. In comparison, if the guest-induced template method is not employed, tetrakis(4-2H-tetrazolyl-5-phenyl)methane can only be crystallized into non-porous crystals in dimethyl sulfoxide. The guest-induced template method proposed in the present invention has mild preparation conditions and a simple process, and is suitable for the large-scale preparation of hydrogen-bonded organic framework materials;

[0031] (3) The tetrazolyl hydrogen-bonded organic framework material disclosed in the present invention can be used to selectively and statically adsorb p-xylene in a variety of xylene mixtures. The pore size of the tetrazolyl hydrogen-bonded organic framework material is commensurate with that of p-xylene, allowing p-xylene molecules to be efficiently arranged within the pores through π…π interactions. However, there is a size exclusion effect on o-xylene and m-xylene. In addition, this tetrazolyl hydrogen-bonded organic framework material has multiple groups of weak CH…π interactions with p-xylene, which enhances its selectivity for p-xylene. The present invention provides a new green adsorbent for achieving low-energy, high-efficiency, and selective separation of p-xylene from C8 aromatic hydrocarbon mixtures at room temperature and pressure.

[0032] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0034] Figure 1 Schematic diagram of the crystal structure of the tetrazolyl hydrogen-bonding organic framework material prepared in Example 1 of the present invention;

[0035] Figure 2 Schematic diagram of the crystal structure of the tetrazolyl hydrogen-bonding organic framework material prepared in Example 2 of the present invention;

[0036] Figure 3 Schematic diagram of the crystal structure of the tetrazolyl hydrogen-bonding organic framework material prepared in Example 5 of the present invention;

[0037] Figure 4 Schematic diagram of the crystal structure prepared in Comparative Example 2 of the present invention;

[0038] Figure 5 The activated HOF-PX of Application Example 1 and the HOF-PX prepared in Example 2 of the present invention are 1 H NMR comparison spectra;

[0039] Figure 6 The XRD comparison patterns of the activated HOF-PX of Application Example 1 and the HOF-PX prepared in Example 2 of the present invention are shown in FIG.

[0040] Figure 7 This is a graph showing the adsorption of p-xylene by the hydrogen-bonded organic framework material at different temperatures in Application Example 1 of the present invention;

[0041] Figure 8 The activated HOF-PX in Application Example 2 of the present invention is adsorbed in different xylene mixtures. 1 H NMR spectrum;

[0042] Figure 9 The activated HOF-PX in Application Example 3 of the present invention is adsorbed in a simulated C8 aromatic mixture. 1 H NMR spectrum. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0044] A specific embodiment of the present invention discloses a tetrazolyl hydrogen-bonded organic framework material. The molecular formula of the tetrazolyl hydrogen-bonded organic framework material is as follows:

[0045] [(C 29 H 20 N 16 ) a (C3H7NO) b (G) c ] n , wherein a, b, and c are all positive integers, n is the number of crystal repeating units, and G is the molecular formula of the guest molecule, wherein the guest molecule includes but is not limited to one or more of 1,4-dioxane, p-xylene, m-xylene, o-xylene, mesitylene, 1,2,4-trichlorobenzene, methyl benzoate, toluene, N,N'-dimethylformamide, etc.

[0046] It should be noted that the novel tetrazole-based hydrogen-bonded organic framework material of the present invention is assembled from monomer molecules and solvent molecules through hydrogen bonding, and has a three-dimensional structure. The four tetrazole functional groups of each monomer molecule are connected to the solvent molecules through NH...O hydrogen bonds. Adjacent monomer molecules are stacked through the synergistic effect of π-π stacking between the tetrazole ring and the benzene ring to form a three-dimensional hydrogen-bonded organic framework. The hydrogen-bonded organic framework has one-dimensional continuous channels filled with guest molecules. Among them, the tetrazole-based hydrogen-bonded organic framework material is a crystal structure, and a, b, and c represent a ratio without a common divisor. For example, a is 1 or 2, b is 4, 6, 8, or 12, and c is 1, 4, or 2. n represents that the crystal structure is an infinitely repeating unit structure, and n can be infinite.

[0047] In a specific embodiment, the tetrazolyl hydrogen bond organic framework material belongs to the orthorhombic system, the space group is Pbcn or Cmcm, and the unit cell parameter is α=β=γ=90°;

[0048] And / or, the tetrazolyl hydrogen bond organic framework material belongs to the orthorhombic crystal system, the space group is Pccn, and the unit cell parameter is α=β=γ=90°;

[0049] And / or, the tetrazolyl hydrogen bond organic framework material belongs to the orthorhombic crystal system, the space group is Pbca, and the unit cell parameter is α=β=γ=90°.

[0050] In a specific embodiment, the tetrazolyl-based hydrogen-bonding organic framework material comprises one-dimensional continuous channels, and the one-dimensional continuous channels extend along the

[010] or

[001] crystal plane direction.

[0051] In a specific embodiment, the size of the one-dimensional continuous channel is p×m, wherein For example,

[0052] For example,

[0053] Preferably, the porosity of the tetrazolyl hydrogen-bonded organic framework material is 16.1% to 32.5%, for example, 16.1%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, or 32.5%.

[0054] Another specific embodiment of the present invention discloses a method for preparing the above-mentioned tetrazolyl hydrogen-bonded organic framework material, comprising the following steps:

[0055] (1) dissolving tetrakis(4-2H-tetrazol-5-ylphenyl)methane in an organic solvent, and filtering the solution to obtain a clear tetrakis(4-2H-tetrazol-5-ylphenyl)methane solution;

[0056] (2) The tetrakis(4-2H-tetrazolyl-5-phenyl)methane clarified solution and guest molecules are subjected to a gas phase diffusion method or a liquid phase diffusion method to obtain the tetrazolyl-based hydrogen bond organic framework material.

[0057] The method for preparing a tetrazole-based hydrogen-bonded organic framework material of the present invention is characterized by utilizing a guest-induced template method to achieve assembly of the porous hydrogen-bonded organic framework material, thereby avoiding close packing of organic building units during crystallization, and achieving a porosity of up to 32.5%. In comparison, without the guest-induced template method, tetrakis(4-2H-tetrazol-5-ylphenyl)methane can only crystallize into non-porous crystals in dimethyl sulfoxide. The guest-induced template method proposed in the present invention has mild preparation conditions and a simple process, making it suitable for large-scale preparation of hydrogen-bonded organic framework materials. The yield of the tetrazole-based hydrogen-bonded organic framework material in the method of the present invention is ≥36.4%, preferably 36.4-67.8%, for example, 37%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or 75%.

[0058] The structural formula of tetrakis(4-2H-tetrazol-5-ylphenyl)methane described in the present invention is as follows:

[0059]

[0060] Specifically, in step (1), the organic solvent is N,N'-dimethylformamide.

[0061] Preferably, the concentration of tetrakis(4-2H-tetrazol-5-ylphenyl)methane in the organic solvent is 16-24 mg / mL, for example, 16 mg / mL, 17 mg / mL, 18 mg / mL, 19 mg / mL, 20 mg / mL, 21 mg / mL, 22 mg / mL, 23 mg / mL, or 24 mg / mL. It should be noted that below this concentration range, no crystals are produced, while above this concentration, a powdery precipitate is produced rather than a crystalline material.

[0062] Specifically, in step (2), the volume ratio of the guest molecule to the organic solvent is ≥2, for example, 2, 3, 4, 5, 6, 7, preferably, the volume ratio is 3-5.

[0063] It should be noted that the guest molecule is also a poor solvent for the monomer molecule tetrakis(4-2H-tetrazol-5-ylphenyl)methane. Below this volume ratio, the solubility of the monomer molecule in the organic solvent cannot be sufficiently reduced, thereby preventing crystallization.

[0064] Specifically, in step (2), the vapor diffusion method is as follows: placing the tetrakis(4-2H-tetrazolyl-5-phenyl)methane clarified solution in an uncovered device, then placing the uncovered device in a covered device containing guest molecules, and performing constant temperature diffusion crystallization to obtain the tetrazolyl hydrogen bonded organic framework material.

[0065] Preferably, the temperature of the isothermal diffusion is 40-70°C, for example, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, and the isothermal diffusion crystallization is 1-4 weeks, for example, 1 week, 2 weeks, 3 weeks, 4 weeks.

[0066] It should be noted that when the temperature is lower than this, the guest molecules can hardly diffuse into the monomer molecule solution through the gas phase, resulting in a too long crystallization time or no crystallization. When the temperature is higher than this, a large number of guest molecules enter the monomer molecule solution, the solubility drops rapidly, and a powdery precipitate is produced rather than a crystalline material.

[0067] Specifically, in step (2), the liquid phase diffusion method is as follows: placing the tetrakis(4-2H-tetrazolyl-5-phenyl)methane clear solution in a container, then slowly spreading the guest molecule on the surface of the tetrakis(4-2H-tetrazolyl-5-phenyl)methane clear solution, sealing the container, and allowing diffusion crystallization at room temperature for 1 to 5 days, for example, 1 day, 2 days, 3 days, 4 days, or 5 days, to obtain the tetrazolyl hydrogen bonded organic framework material.

[0068] Another specific embodiment of the present invention discloses an activated material for separating p-xylene. The activated material is prepared by removing guest molecules from the aforementioned tetrazolyl hydrogen-bonding organic framework material through a solvent exchange method, followed by vacuum activation to obtain the activated material. Another specific embodiment of the present invention discloses the use of the aforementioned tetrazolyl hydrogen-bonding organic framework material for static adsorption of p-xylene.

[0069] The structural units of the tetrazole-based hydrogen-bonding organic framework material described herein are tetrakis(4-2H-tetrazol-5-ylphenyl)methane, N,N'-dimethylformamide, and guest molecules interconnected by intermolecular hydrogen bonds, and assembled into a crystalline material under the synergistic effect of π-π stacking. This hydrogen-bonding organic framework material has one-dimensional through-holes, and its pore size and porosity can be regulated by the choice of guest molecules. The tetrazole functional groups introduced into the hydrogen-bonding organic framework material, whose open nitrogen atoms not involved in hydrogen bonding, can provide adsorption sites for the selective separation of xylene isomers.

[0070] The tetrazolyl-based hydrogen-bonding organic framework disclosed in this invention can be used to selectively statically adsorb p-xylene in various xylene mixtures. Its pore size is commensurate with that of p-xylene, allowing p-xylene molecules to be efficiently arranged within the pores through π…π interactions. However, size exclusion occurs for o-xylene and m-xylene. Furthermore, this tetrazolyl-based hydrogen-bonding organic framework exhibits multiple weak CH…π interactions with p-xylene, enhancing its selectivity for p-xylene. This invention provides a new green adsorbent for the low-energy, high-efficiency, selective separation of p-xylene from C8 aromatic hydrocarbon mixtures at ambient temperature and pressure.

[0071] Specifically, the application includes the following steps:

[0072] (a) removing guest molecules from a tetrazole-based hydrogen-bonded organic framework material by a solvent exchange method, and vacuum-activating the material to obtain an activated material;

[0073] (b) soaking the activated material in a C8 aromatic hydrocarbon mixture, centrifuging, removing the supernatant, washing, and drying to obtain a tetrazolyl hydrogen-bonded organic framework material that adsorbs p-xylene.

[0074] Specifically, in step (a), the solvent is n-hexane or n-pentane, preferably n-pentane.

[0075] Preferably, in step (a), the number of solvent exchanges is 4 to 6 times, for example, 4 times, 5 times, or 6 times, with an interval of 2 to 4 hours between each exchange, for example, 2 hours, 2.5 hours, 3.0 hours, 3.5 hours, or 4 hours. To maintain the crystallinity of the material, the total solvent exchange time should not exceed 24 hours.

[0076] Specifically, in step (a), the temperature of vacuum activation is less than 50°C, for example, 48°C, 46°C, 44°C, 42°C, 40°C, 38°C, 36°C, 34°C, 32°C, 30°C, 28°C, 26°C, 24°C. Above this temperature, the crystallinity decreases, and the activation time is ≥24h, for example, 24h, 25h, 26h, 27h, 28h, 29h, 30h. Preferably, the temperature is 30°C and the activation time is 48h.

[0077] The tetrazolyl hydrogen-bonded organic framework material of the present invention has the following selectivity coefficients for xylene: p-xylene / m-xylene selectivity coefficient ≥ 2.9, p-xylene / o-xylene selectivity coefficient ≥ 3, and p-xylene / ethylbenzene selectivity coefficient ≥ 4.9.

[0078] The technical solution of the present invention is further explained below in conjunction with specific embodiments.

[0079] Example 1

[0080] A tetrazolyl-based hydrogen-bonded organic framework material of this embodiment is prepared by vapor phase diffusion, and the specific steps include the following:

[0081] (1) Weigh 50 mg of tetrakis(4-2H-tetrazol-5-ylphenyl)methane and dissolve it in 3 mL of N,N'-dimethylformamide. After sonication, filter through a 0.45 μm nylon filter to obtain a clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane.

[0082] (2) The clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane was placed in a 10 mL uncovered glass bottle, which was then placed in a 50 mL wide-mouthed glass bottle with a lid containing 10 mL of 1,4-dioxane. The bottle cap was tightened and the reaction was carried out in a constant temperature oven at 40°C for two weeks to obtain colorless and transparent block crystals of HOF-Dio (tetrazolyl hydrogen-bonded organic framework material) with a yield of 54.4% (calculated based on the mass of tetrakis(4-2H-tetrazol-5-ylphenyl)methane).

[0083] The crystal structure diagram of the tetrazolyl hydrogen bond organic framework material prepared in this example is shown in FIG. Figure 1As shown, HOF-Dio has a one-dimensional channel in the

[001] crystal plane direction, and the channel size is The porosity is 19.4%.

[0084] Its structure was determined by single crystal X-ray diffractometry, and the space group was Pbcn, and the unit cell parameters were α=β=γ=90°, Z=4.

[0085] The molecular formula of the tetrazolyl hydrogen bond organic framework material prepared in this embodiment is as follows: [(C 29 H 20 N 16 ) a (C3H7NO) b (G) c ] n , where a=1, b=4, c=4, n is the infinite number of crystal repeating units, and G is 1,4-dioxane with the molecular formula C4H8O2.

[0086] Example 2

[0087] A tetrazolyl-based hydrogen-bonding organic framework material of this embodiment is prepared by liquid phase diffusion, and the specific steps include the following:

[0088] (1) Weigh 100 mg of tetrakis(4-2H-tetrazol-5-ylphenyl)methane and dissolve it in 5 mL of N,N'-dimethylformamide. After sonication, filter through a 0.45 μm nylon filter to obtain a clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane.

[0089] (2) A clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane was placed in a 20 mL glass bottle with a lid, 15 mL of p-xylene was slowly layered on top of the solution, the bottle cap was tightened, and the reaction was carried out at room temperature for 24 hours to obtain colorless and transparent block crystals of HOF-PX (tetrazolyl hydrogen-bonded organic framework material) with a yield of 46.4% (calculated based on the mass of tetrakis(4-2H-tetrazol-5-ylphenyl)methane).

[0090] The crystal structure diagram of the tetrazolyl hydrogen bond organic framework material prepared in this example is shown in FIG. Figure 2 As shown, HOF-PX has a one-dimensional channel in the

[010] crystal plane direction, and the channel size is The porosity is 32.1%.

[0091] Its structure was determined by single crystal X-ray diffractometer and it belongs to the orthorhombic system with space group Pccn and unit cell parameters α=β=γ=90°, Z=8.

[0092] The molecular formula of the tetrazolyl hydrogen bond organic framework material prepared in this embodiment is as follows: [(C 29 H 20 N 16 ) a (C3H7NO) b (G) c ] n , where a=1, b=4, c=2, n is the number of infinite crystal repeating units, and G is the molecular formula of p-xylene, C8H 10 .

[0093] Example 3

[0094] A tetrazolyl-based hydrogen-bonded organic framework material of this embodiment is prepared by vapor phase diffusion, and the specific steps include the following:

[0095] (1) Weigh 72 mg of tetrakis(4-2H-tetrazol-5-ylphenyl)methane and dissolve it in 3 mL of N,N'-dimethylformamide. After sonication, filter through a 0.45 μm nylon filter to obtain a clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane.

[0096] (2) The clear solution of tetrakis(4-2H-tetrazolyl-5-ylphenyl)methane was placed in a 10 mL uncovered glass bottle, which was then placed in a 50 mL wide-mouthed glass bottle with a lid containing 12 mL of methyl benzoate. The bottle cap was tightened and the mixture was reacted in a 70°C constant temperature oven for one week to obtain colorless and transparent block crystals of HOF-MB (tetrazolyl hydrogen-bonded organic framework material) with a yield of 50.9% (calculated based on the mass of tetrakis(4-2H-tetrazolyl-5-ylphenyl)methane). The tetrazolyl hydrogen-bonded organic framework material HOF-MB prepared in this example has a one-dimensional pore in the

[001] crystal plane direction, and the pore size is The porosity is 31.9%.

[0097] Its structure was determined by single crystal X-ray diffractometry, and the space group was Pbcn, and the unit cell parameters were α=β=γ=90°, Z=8.

[0098] The molecular formula of the tetrazolyl hydrogen bond organic framework material prepared in this embodiment is as follows: [(C 29 H 20 N 16 ) a (C3H7NO) b (G) c ]n , where a=2, b=8, c=1, n is the infinite number of crystal repeating units, and G is the molecular formula of methyl benzoate C8H8O2.

[0099] Example 4

[0100] A tetrazolyl-based hydrogen-bonded organic framework material of this embodiment is prepared by vapor phase diffusion, and the specific steps include the following:

[0101] (1) Weigh 50 mg of tetrakis(4-2H-tetrazol-5-ylphenyl)methane and dissolve it in 3 mL of N,N'-dimethylformamide. After sonication, filter through a 0.45 μm nylon filter to obtain a clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane.

[0102] (2) The clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane was placed in a 10 mL uncovered glass bottle, which was then placed in a 50 mL wide-mouthed glass bottle with a lid and filled with 15 mL of mesitylene. The bottle cap was tightened and the mixture was reacted in a constant temperature oven at 50°C for four weeks to obtain colorless, transparent block crystals of HOF-TMB (tetrazolyl hydrogen-bonding organic framework material) with a yield of 52.4% (calculated based on the mass of tetrakis(4-2H-tetrazol-5-ylphenyl)methane).

[0103] The tetrazolyl hydrogen-bonded organic framework material HOF-TMB prepared in this embodiment has a one-dimensional pore in the

[001] crystal plane direction. The pore size is The porosity is 31.4%.

[0104] Its structure was determined by single crystal X-ray diffractometry, and the space group was Pbcn, and the unit cell parameters were α=β=γ=90°, V= Z=4.

[0105] The molecular formula of the tetrazolyl hydrogen bond organic framework material prepared in this embodiment is as follows: [(C 29 H 20 N 16 ) a (C3H7NO) b (G) c ] n , where a=1, b=6, c=1, n is the number of infinite crystal repeating units, and G is the molecular formula of mesitylene C9H 12 .

[0106] Example 5

[0107] A tetrazolyl-based hydrogen-bonding organic framework material of this embodiment is prepared by liquid phase diffusion, and the specific steps include the following:

[0108] (1) Weigh 100 mg of tetrakis(4-2H-tetrazol-5-ylphenyl)methane and dissolve it in 5 mL of N,N'-dimethylformamide. After sonication, filter through a 0.45 μm nylon filter to obtain a clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane.

[0109] (2) A clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane was placed in a 20 mL glass bottle with a lid, 15 mL of 1,2,4-trichlorobenzene was slowly layered on top of the solution, the bottle cap was tightened, and the reaction was carried out at room temperature for 5 days to obtain colorless and transparent block crystals of HOF-TCB (tetrazolyl hydrogen-bonded organic framework material) with a yield of 41.9% (calculated based on the mass of tetrakis(4-2H-tetrazol-5-ylphenyl)methane).

[0110] The crystal structure diagram of the tetrazolyl hydrogen bond organic framework material prepared in this example is shown in FIG. Figure 3 As shown, HOF-TCB has a one-dimensional channel in the

[010] crystal plane direction, and the channel size is The porosity is 32.5%.

[0111] Its structure was determined by single crystal X-ray diffractometer and it belongs to the orthorhombic system with space group Pbca and unit cell parameters α=β=γ=90°, Z=8.

[0112] The molecular formula of the tetrazolyl hydrogen bond organic framework material prepared in this embodiment is as follows: [(C 29 H 20 N 16 ) a (C3H7NO) b (G) c ] n , where a=1, b=4, c=2, n is the infinite number of crystal repeating units, and G is the molecular formula of 1,2,4-trichlorobenzene C6H6Cl3.

[0113] Example 6

[0114] A tetrazolyl-based hydrogen-bonding organic framework material of this embodiment is prepared by liquid phase diffusion, and the specific steps include the following:

[0115] (1) Weigh 50 mg of tetrakis(4-2H-tetrazol-5-ylphenyl)methane and dissolve it in 3 mL of N,N'-dimethylformamide. After sonication, filter through a 0.45 μm nylon filter to obtain a clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane.

[0116] (2) A clear solution of tetrakis(4-2H-tetrazol-5-ylphenyl)methane was placed in a 20 mL glass bottle with a lid. 15 mL of toluene was slowly layered on top of the solution, the bottle cap was tightened, and the reaction was carried out at room temperature for 3 days to obtain colorless, transparent block crystals of HOF-Tol (tetrazolyl hydrogen-bonded organic framework material) with a yield of 52.3% (calculated based on the mass of tetrakis(4-2H-tetrazol-5-ylphenyl)methane).

[0117] The tetrazolyl hydrogen-bonded organic framework material HOF-Tol prepared in this embodiment has a one-dimensional pore in the

[001] crystal plane direction, and the pore size is The porosity is 16.1%.

[0118] Its structure was determined by single crystal X-ray diffractometer and it belongs to the orthorhombic system with space group Cmcm and unit cell parameters α=β=γ=90°, Z=4.

[0119] The molecular formula of the tetrazolyl hydrogen bond organic framework material prepared in this embodiment is as follows: [(C 29 H 20 N 16 ) a (C3H7NO) b (G) c ] n , where a=2, b=8, c=1, n is the infinite number of crystal repeating units, and G is the molecular formula of toluene C7H8.

[0120] Comparative Example 1

[0121] The preparation method of the organic framework material in this comparative example is the same as that in Example 1, except that in step (2), the guest molecule 1,4-dioxane is replaced by a poor solvent acetone or ethyl acetate, and the reaction is carried out at room temperature for 1 month until the poor solvent is completely diffused into the monomer solution and no crystals are produced.

[0122] Comparative Example 2

[0123] The preparation method of the organic framework material of this comparative example is the same as that of Example 1, except that in step (1), N,N'-dimethylformamide is replaced with dimethyl sulfoxide. Place it in a 10mL glass bottle without a lid and evaporate at room temperature to obtain colorless and transparent flaky crystals of CP-DMSO. Its structure is determined by single crystal X-ray diffractometer, and the unit cell parameters are α=β=γ=90°, Z=8.

[0124] Figure 4The crystal structure diagram of the crystal shows that CP-DMSO is a densely packed crystal without a porous structure. This comparative example illustrates that the method for preparing hydrogen-bonded organic framework materials disclosed in the present invention can successfully obtain porous hydrogen-bonded organic framework materials that cannot be obtained by conventional crystallization methods through the guest-induced template effect.

[0125] Application Example 1

[0126] This application example uses a tetrazolyl-based hydrogen-bonding organic framework material in the static adsorption of p-xylene. The specific steps are as follows:

[0127] (a) The tetrazolyl hydrogen-bonded organic framework material (HOF-PX) prepared in Example 2 was immersed in n-pentane for 8 h, and fresh n-pentane solvent was replaced every 2 h until the p-xylene molecules in the pores were completely replaced. The replaced material was vacuum activated at 30° C. for 24 h to obtain an activated material. The activated material (activated HOF-PX) was compared with the HOF-PX prepared in Example 2. 1 H NMR comparison spectra Figure 5 As shown, the p-xylene in the surface pores has been completely removed.

[0128] The XRD comparison of the activated HOF-PX and the HOF-PX prepared in Example 2 is shown in FIG. Figure 6 As shown, the crystallinity of the hydrogen bond organic framework material did not decrease significantly before and after activation, and the framework structure did not change significantly, which proved the stability of the material.

[0129] (b) Weigh 30 mg of activated HOF-PX and place it in four 10 mL glass bottles with lids, add 3 mL of p-xylene to completely immerse the activated HOF-PX, and tighten the bottle caps. Place the four glass bottles at 4°C, 25°C, 60°C, and 80°C for 72 hours. Use a syringe with a needle to remove the liquid from the glass bottle and quickly wash the remaining solid in the bottle with n-pentane three times, then dry it at room temperature. Dissolve 10 mg of hydrogen-bonded organic framework material adsorbed with xylene in 0.75 mL of DMSO-d6. 1 H NMR test, calculate the amount of p-xylene adsorption. The results show that ( Figure 7 ), the maximum adsorption capacity of hydrogen-bonded organic framework materials for p-xylene is 1.25 mmol / g at 60 °C.

[0130] Application Example 2

[0131] This application example is identical to Application Example 1, except that in step (b), the p-xylene in the four glass bottles was replaced with a 1:1 molar ratio of p-xylene / m-xylene, a p-xylene / o-xylene mixture, a p-xylene / ethylbenzene mixture, and a 1:1:1 molar ratio of p-xylene / m-xylene / o-xylene mixture, respectively. Adsorption was performed at 25°C for 72 hours.

[0132] After activation, HOF-PX was adsorbed in different xylene mixtures. 1 H NMR spectrum Figure 8 As shown, after calculation, the selectivity coefficients of p-xylene / m-xylene, p-xylene / o-xylene, and p-xylene / ethylbenzene in the binary mixture are 3.6, 4.9, and 21.7, respectively; the selectivity coefficients of p-xylene / m-xylene and p-xylene / o-xylene in the ternary mixture are 3.7 and 3.1, respectively.

[0133] The inventors also conducted the above test on tetrazolyl hydrogen-bonded organic framework materials prepared in other examples, and the results were basically the same. Due to limited space, they are not listed one by one.

[0134] Application Example 3

[0135] This application example is the same as application example 1, except that in step (b), 30 mg of activated HOF-PX was weighed and placed in a 10 mL glass bottle with a lid, and 2 mL of a C8 aromatic hydrocarbon mixture was added, the composition of which was 19% ethylbenzene, 44% m-xylene, 20% o-xylene, and 17% p-xylene by mass. The results showed that ( Figure 9 ), the selectivity coefficients of p-xylene / m-xylene, p-xylene / o-xylene, and p-xylene / ethylbenzene in the C8 aromatic hydrocarbon mixture are 3.2, 3.9, and 4.9, respectively.

[0136] The inventors also conducted the above test on tetrazolyl hydrogen-bonded organic framework materials prepared in other examples, and the results were basically the same. Due to limited space, they are not listed one by one.

[0137] Application Example 4

[0138] This application example is the same as application example 2, except that, in step (a), the tetrazolyl hydrogen-bonded organic framework material (HOF-PX) prepared in example 2 is replaced by the existing MIL-125(Ti)-NH2.

[0139] After calculation, the selectivity coefficients of p-xylene / m-xylene, p-xylene / o-xylene, and p-xylene / ethylbenzene in the binary mixture are 3.4, 2.8, and 1.6, respectively; the selectivity coefficients of p-xylene / m-xylene and p-xylene / o-xylene in the ternary mixture are 3.0 and 2.2, respectively.

[0140] Compared with Application Example 2, the tetrazolyl hydrogen-bonded organic framework material of the present invention has higher selectivity for p-xylene than the existing organic framework materials, and in particular, the separation effect for ethylbenzene is more obvious.

[0141] The inventors also conducted the above test on tetrazolyl hydrogen-bonded organic framework materials prepared in other examples, and the results were basically the same. Due to limited space, they are not listed one by one.

[0142] Application Example 5

[0143] The tetrazolyl hydrogen-bonded organic framework materials prepared in Examples 1-6 were respectively placed at 60° C. for 72 hours using the method of Application Example 1. The maximum adsorption capacity of the tetrazolyl hydrogen-bonded organic framework materials for p-xylene, o-xylene, m-xylene and ethylbenzene was tested. The results are shown in Table 1.

[0144] Table 1

[0145]

[0146] As can be seen from the above table, the tetrazolyl hydrogen-bonded organic framework material prepared by the present invention has a significantly better adsorption capacity for p-xylene than o-xylene, m-xylene and ethylbenzene.

[0147] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A tetrazolyl hydrogen-bonded organic framework material, characterized in that: The molecular formula of the tetrazolyl hydrogen bond organic framework material is as follows: [(C 29 H 20 N 16 ) a (C3H7NO) b (G) c ] n , wherein a, b, and c are all positive integers, n is the number of crystal repeating units, and G is the molecular formula of a guest molecule, wherein the guest molecule includes but is not limited to one or more of 1,4-dioxane, p-xylene, mesitylene, 1,2,4-trichlorobenzene, methyl benzoate, and toluene; The tetrazolyl hydrogen bond organic framework material is prepared by the following method: (1) dissolving tetrakis(4-2H-tetrazol-5-ylphenyl)methane in an organic solvent and filtering to obtain a clear tetrakis(4-2H-tetrazol-5-ylphenyl)methane solution; (2) using a gas phase diffusion method or a liquid phase diffusion method to obtain the tetrazolyl hydrogen bond organic framework material; Wherein, in step (1), the organic solvent is N,N'-dimethylformamide; And / or, the concentration of the tetrakis(4-2H-tetrazol-5-ylphenyl)methane in the organic solvent is 16-24 mg / mL.

2. A tetrazolyl hydrogen-bonded organic framework material according to claim 1, characterized in that: The tetrazolyl hydrogen-bonded organic framework material belongs to the orthorhombic crystal system, the space group is Pbcn or Cmcm, the unit cell parameters are a = 19.9~20.7 Å, b = 14.1~15.2 Å, c = 20.6~20.9 Å, α = β = γ = 90°; and / or, the tetrazolyl hydrogen-bonded organic framework material belongs to the orthorhombic crystal system, the space group is Pccn, the unit cell parameters are a = 20.0806(3) Å, b = 20.5072(2) Å, c = 29.1526(5) Å, α = β = γ = 90°; And / or, the tetrazolyl hydrogen-bonded organic framework material belongs to the orthorhombic crystal system, the space group is Pbca, the unit cell parameters are a = 15.1167(3) Å, b = 20.3431(3) Å, c = 39.4033(5) Å, α = β = γ = 90°.

3. A tetrazolyl hydrogen-bonding organic framework material according to claim 1 or 2, characterized in that: The tetrazolyl hydrogen-bonded organic framework material comprises one-dimensional continuous channels, and the one-dimensional continuous channels extend along the [010] or [001] crystal plane direction.

4. A tetrazolyl hydrogen-bonded organic framework material according to claim 3, characterized in that: The size of the one-dimensional continuous channel is p×m, where p = 3.5~4.8 Å, m = 4.6~7.0 Å.

5. A tetrazolyl hydrogen-bonding organic framework material according to claim 3, characterized in that: The porosity of the tetrazolyl hydrogen-bonded organic framework material is 16.1-32.5%.

6. A method for preparing the tetrazolyl hydrogen-bonding organic framework material according to any one of claims 1 to 5, characterized in that: The steps include: (1) dissolving tetrakis(4-2H-tetrazol-5-ylphenyl)methane in an organic solvent and filtering to obtain a clear tetrakis(4-2H-tetrazol-5-ylphenyl)methane solution; (2) The tetrakis(4-2H-tetrazolyl-5-phenyl)methane clarified solution and guest molecules are subjected to a gas phase diffusion method or a liquid phase diffusion method to obtain the tetrazolyl-based hydrogen bond organic framework material.

7. The preparation method according to claim 6, characterized in that In step (1), the organic solvent is N,N'-dimethylformamide; And / or, the concentration of the tetrakis(4-2H-tetrazol-5-ylphenyl)methane in the organic solvent is 16-24 mg / mL.

8. The preparation method according to claim 6, characterized in that In step (2), the volume ratio of the guest molecule to the organic solvent is ≥2.

9. The preparation method according to claim 6, characterized in that In step (2), the vapor diffusion method is specifically as follows: placing the tetrakis(4-2H-tetrazolyl-5-phenyl)methane clarified solution in an uncovered device, then placing the uncovered device in a covered device containing guest molecules, and performing constant temperature diffusion crystallization to obtain the tetrazolyl hydrogen bond organic framework material.

10. The preparation method according to claim 6, characterized in that In step (2), the liquid phase diffusion method is specifically as follows: placing the tetrakis(4-2H-tetrazolyl-5-phenyl)methane clear solution in a container, then slowly spreading the guest molecules on the surface of the tetrakis(4-2H-tetrazolyl-5-phenyl)methane clear solution, sealing the container, and performing diffusion crystallization at room temperature to obtain the tetrazolyl hydrogen bond organic framework material.

11. An activated material for separating p-xylene, characterized in that: The activated material is prepared by the following method: removing guest molecules from the tetrazolyl hydrogen bond organic framework material described in any one of claims 1 to 5 or the tetrazolyl hydrogen bond organic framework material prepared by the method of any one of claims 6 to 10 by a solvent exchange method, and vacuum activation to obtain the activated material.

12. Use of the tetrazolyl hydrogen-bonding organic framework material according to any one of claims 1 to 5 or the tetrazolyl hydrogen-bonding organic framework material prepared by the method according to any one of claims 6 to 10 in the static adsorption of p-xylene or in the separation of p-xylene from a mixture, characterized in that: The application comprises the following steps: (a) The tetrazolyl hydrogen-bonded organic framework material is subjected to solvent exchange to remove guest molecules and vacuum activation to obtain an activated material; (b) Immersing the activated material in a C8 aromatic hydrocarbon mixture, centrifuging, removing the supernatant, washing, and drying to obtain a tetrazolyl hydrogen-bonded organic framework material adsorbing p-xylene.

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