Flexible water-stable coordination-confined materials, preparation method and application thereof

Abstract

The application provides a flexible water-stable coordination confined material as well as a preparation method and application thereof, and belongs to the technical field of metal organic coordination polymers. The flexible water-stable coordination confined material is obtained through a coordination reaction of metal ions and oxygen-based organic ligands; wherein the metal ions are selected from any one of V 4+ , Zr 4+ , Cu 2+ , Ti 4+ , Al 3+ , Cr 3+ , Fe 3+ ; and the oxygen-based organic ligands are selected from any one of nitrogen heterocyclic phosphonic acid organic ligands, alkyl phosphonic acid organic ligands, sugar organic ligands, phenolic hydroxyl organic ligands, alcoholic hydroxyl organic ligands, nitrogen heterocyclic hydroxyl organic ligands and enolic organic ligands.

Description

Technical Field

[0001] This application relates to the field of metal-organic coordination polymer technology, specifically to a flexible water-stable coordination confinement material, its preparation method, and its application. Background Technology

[0002] Heavy water (D2O), as a core carrier of deuterium isotopes, is widely used in basic research and industrial fields. Its efficient separation and purification is a core prerequisite for the large-scale utilization of deuterium isotopes. However, the content of heavy water in natural water is only about 0.015%, and the molecular dynamic diameters of water (H2O) and heavy water are basically the same, with very little difference in their physicochemical properties. This makes the efficient separation of the two a long-standing technical challenge in this field.

[0003] Current methods for heavy water separation mainly rely on traditional methods, but these methods generally suffer from low separation factors (only 1.02-1.05) and are accompanied by significant drawbacks such as large equipment size, high energy consumption, and high separation costs, making it difficult to meet the industrial demand for large-scale, low-cost heavy water extraction. Therefore, developing water and heavy water separation technologies with lower energy consumption and higher efficiency has become a core breakthrough for promoting the industrial application of deuterium isotopes, and has important practical significance and application value.

[0004] In recent years, coordination-confined materials with flexible structures have gradually demonstrated unique advantages in the field of molecular separation. The core characteristic of coordination-confined materials lies in the reversible transformation of their framework structure under external stimuli, enabling dynamic control of pore size and chemical environment through local dynamic movement or overall "breathing" behavior. Specifically, utilizing the localized pore-controlled flexibility of coordination-confined materials, the subtle differences in diffusion rates between H₂O and D₂O can be effectively amplified, providing a kinetic control mechanism for achieving the challenging separation of H₂O and D₂O. Simultaneously, the water stability of coordination-confined materials is a key factor determining their practical application: high water stability not only requires the coordination-confined material to maintain its framework structure integrity in humid environments but also ensures that its dynamic response function can be maintained stably over a long period in aqueous environments. This is one of the core prerequisites for the practical application of coordination-confined materials in water and heavy water separation.

[0005] However, existing technologies have not yet been able to effectively integrate structural flexibility and high water stability into the same material system, which severely restricts the large-scale application of flexible coordination confinement materials in the field of water and heavy water separation. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a flexible water-stable coordination confinement material, its preparation method, and its application, aiming to at least partially solve the above-mentioned technical problems. The specific technical solution provided by this application is as follows.

[0007] As a first aspect of this application, a flexible water-stable coordination confinement material is provided, which is obtained by a coordination reaction between a metal ion and an oxygen-based organic ligand; wherein the metal ion is selected from V 4+ Zr 4 + Cu 2+ Ti 4+ Al 3+ Cr 3+ Fe 3+ Any one of the following; the oxygen-based organic ligand is selected from any one of the following: nitrogen-containing heterocyclic phosphonic acid organic ligands, alkyl phosphonic acid organic ligands, sugar organic ligands, phenolic hydroxyl organic ligands, alcoholic hydroxyl organic ligands, nitrogen-containing heterocyclic hydroxyl organic ligands, and enol organic ligands.

[0008] As a second aspect of this application, a method for preparing a flexible water-stable coordination confinement material is provided, comprising: providing a precursor solution containing an oxygen-containing organic ligand; adding a metal precursor containing metal ions to the precursor solution; mixing evenly and then carrying out a coordination reaction; and after the reaction is completed, sequentially performing filtration, washing, drying and activation treatments to obtain the flexible water-stable coordination confinement material.

[0009] As a third aspect of this application, an application of a flexible water-stable coordination confinement material in the adsorption and separation of water and heavy water is provided.

[0010] In this application embodiment, a flexible water-stabilized coordination confinement material (hereinafter referred to as coordination confinement material) is provided, which is obtained by screening V 4+ Zr 4+ Cu 2+ Ti 4+ Al 3+ Cr 3+ Fe 3+ The coordination assembly of metal ions with specific strong-coordinating oxygen-based organic ligands effectively integrates the structural flexibility and high water stability of the coordination-confined material. This significantly improves separation selectivity and separation factor by amplifying the diffusion difference between H₂O and D₂O through the local dynamic movement or overall reversible deformation of the coordination-confined material framework, overcoming the performance limitations of traditional separation methods. Simultaneously, it ensures that the coordination-confined material maintains structural integrity and stable dynamic response in the aqueous environment over a long period. The preparation method is simple, mild, and highly controllable, facilitating large-scale production and effectively reducing preparation costs. Applying this coordination-confined material to the adsorption and separation of water and heavy water achieves high-efficiency separation with low energy consumption, perfectly meeting the industrialization needs for large-scale heavy water acquisition and providing key technical support for the widespread application of deuterium isotopes. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the crystal structure of V-MDP-1 in Embodiment 1 of this application;

[0012] Figure 2 This is the powder X-ray diffraction pattern of V-MDP-1 in Example 1 of this application;

[0013] Figure 3 This is an adsorption separation diagram of water and heavy water of V-MDP-1 at 303K in Example 1 of this application;

[0014] Figure 4 This is a schematic diagram of the crystal structure of V-MDP-2 in Embodiment 2 of this application;

[0015] Figure 5 This is the powder X-ray diffraction pattern of V-MDP-2 in Example 2 of this application;

[0016] Figure 6 This is an adsorption separation diagram of water and heavy water of V-MDP-2 at 303K in Example 2 of this application;

[0017] Figure 7 This is a schematic diagram of the crystal structure of Zr-SA-1 in Embodiment 3 of this application;

[0018] Figure 8 This is the powder X-ray diffraction pattern of Zr-SA-1 in Example 3 of this application;

[0019] Figure 9 This is a diagram showing the adsorption and separation of water and heavy water in Zr-SA-1 at 303K in Example 3 of this application;

[0020] Figure 10 This is the powder X-ray diffraction pattern of Zr-SA-2 in Example 4 of this application;

[0021] Figure 11 This is a diagram showing the adsorption and separation of water and heavy water in Zr-SA-2 at 303K in Example 4 of this application;

[0022] Figure 12 This is a schematic diagram of the crystal structure of Cu-MDP in Example 5 of this application;

[0023] Figure 13 This is the powder X-ray diffraction pattern of Cu-MDP in Example 5 of this application;

[0024] Figure 14 This is an adsorption separation diagram of water and heavy water in Cu-MDP at 303K in Example 5 of this application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0026] In realizing the concept of this application, it was discovered that the structural characteristics and coordination ability of organic ligands are the core key to constructing coordination confinement materials that combine flexibility and high water stability. Strongly coordinating oxygen-based organic ligands with well-defined geometric configurations, strong structural predictability, rich coordination modes, and excellent bonding ability can provide ideal structural building blocks for coordination confinement materials. Among them, ligands such as methylene diphosphonic acid (MDP) and 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid, SA) can endow coordination confinement materials with a synergistic effect of structural flexibility and coordination stability through diverse coordination interactions with metal ions. Developing coordination confinement materials constructed with such ligands and systematically studying the correlation between their structure and separation performance is of great significance for promoting technological breakthroughs in isotope water separation materials. Based on this, this application provides a flexible water-stable coordination confinement material. By screening specific metal ions and directionally coordinating and assembling them with oxygen-containing organic ligands such as nitrogen heterocyclic phosphonates, alkyl phosphonates, and sugars, a coordination confinement material system with a controllable dimensional coordination framework is constructed. This achieves an effective integration of the flexibility of the coordination confinement material structure and high water stability, thereby achieving efficient adsorption and separation of water and heavy water. At the same time, it provides theoretical and technical support for the structural design and performance optimization of isotope water separation materials.

[0027] As a first aspect of this application, a flexible water-stable coordination confinement material is provided, which is obtained by a coordination reaction between a metal ion and an oxygen-based organic ligand; wherein the metal ion is selected from V 4+ Zr 4 + Cu 2+ Ti 4+ Al 3+ Cr 3+ Fe 3+ Any one of the following; the oxygen-based organic ligand is selected from any one of the following: nitrogen-containing heterocyclic phosphonic acid organic ligands, alkyl phosphonic acid organic ligands, sugar organic ligands, phenolic hydroxyl organic ligands, alcoholic hydroxyl organic ligands, nitrogen-containing heterocyclic hydroxyl organic ligands, and enol organic ligands.

[0028] In the embodiments of this application, the flexible water-stabilized coordination confinement material provided in this application, based on the soft and hard acid-base theory, V 4+ Zr 4+ Cu 2+ Ti 4+ Al 3+ Cr 3+ Fe 3+The coordination bonds formed between metal ions and oxygen-based organic ligands have higher bond energies and stronger stability, which can fully meet the requirements for the adsorption and separation of water and heavy water. Through the directional coordination assembly of specific metal ions and specific oxygen-based organic ligands, the strong bonding ability of the oxygen-based organic ligands endows the coordination confinement material with excellent water stability. At the same time, the structural characteristics of the oxygen-based organic ligands endow the coordination confinement material with flexibility, which can effectively amplify the diffusion difference between H2O and D2O, improve separation efficiency, solve the technical problem that traditional coordination materials cannot balance flexibility and water stability, adapt to the practical application needs of water and heavy water adsorption and separation, and provide support for the large-scale utilization of deuterium isotopes.

[0029] In some embodiments, the flexible water-stable coordination confinement material is a one-dimensional chain structure, a two-dimensional layered structure, or a three-dimensional framework structure formed by metal ions and oxygen-based organic ligands connected by coordination bonds.

[0030] Specifically, one-dimensional chain structures extend infinitely in a single direction, with chains stacked between them by intermolecular forces (such as van der Waals forces and weak hydrogen bonds). Chain segments can locally oscillate and twist within the limits allowed by intermolecular forces, forming local structural flexibility. This flexibility does not disrupt the stability of the intrachain coordination bonds, but only manifests as dynamic movement at the chain segment level. Two-dimensional layered structures form a continuous coordination network along two mutually perpendicular directions, with layers connected by weak interactions (such as interlayer hydrogen bonds and π-π stacking interactions). The dynamic tunability of these weak interactions allows for relative slippage, bending, or slight interlayer peeling-repositioning between layers. The system is designed to achieve flexible deformation of a two-dimensional layered structure, which can be restored to its initial state after deformation. The three-dimensional framework structure is a three-dimensional porous skeleton with dynamically adjustable channels. The intrinsic flexibility of the oxygen-based organic ligands (such as the torsion of aliphatic chains and the slight deformation ability of ring structures) can be transferred to the entire three-dimensional porous skeleton. This manifests as local dynamic movement of the oxygen-based organic ligands (local structural flexibility) and can also drive the three-dimensional porous skeleton to undergo overall dynamic changes such as channel contraction-expansion and slight twisting (overall framework flexibility). Moreover, all such deformations are reversible and do not affect the overall structural integrity of the three-dimensional porous skeleton.

[0031] Furthermore, the coordination number of the metal ions in the flexible water-stable coordination confinement material is 1-8, for example, it can be 1, 2, 3, 4, 5, 6, 7, or 8. The oxygen-based organic ligand coordinates with the metal ions through its oxygen atom.

[0032] Specifically, this coordination number range fully covers V 4+ Zr 4+ Cu 2+The diverse coordination modes of metal ions with oxygen-based organic ligands such as nitrogen-containing heterocyclic phosphonates and alkyl phosphonates include both simple coordination structures formed by metal ions and oxygen-based organic ligands under low coordination (e.g., 1-4) and stable coordination environments constructed by metal ions through polydentate oxygen-based organic ligands under high coordination (e.g., 5-8). The bonding strength and spatial configuration of metal ions and oxygen-based organic ligands can be flexibly controlled according to actual conditions. Low coordination is beneficial to enhance the local structural flexibility of coordination confinement materials, while high coordination can improve the water stability of coordination confinement materials by increasing the number of coordination bonds. The adaptability of different coordination numbers can also directionally control the spatial structural dimension of coordination confinement materials (one-dimensional chain structure, two-dimensional layered structure, three-dimensional framework structure), ultimately achieving synergistic optimization of the flexibility and water stability of coordination confinement materials, ensuring that they maintain stable dynamic response and separation performance during the adsorption and separation of water and heavy water.

[0033] In some embodiments, the azacyclic phosphonic acid organic ligands are selected from (piperazine-1,4-diylbis(methylene))bis(phosphonic acid), (1,4-diazacycloheptane-1,4-diylbis(methylene))bis(phosphonic acid), (S)-2-methyl-1,4-bis(phosphonomethyl)piperazine, 1,4-bis(phosphonomethyl)-2,5-piperazinedione, and 1,4,7-triazacyclononane-1,4,7-tris(methylenephosphonic acid); the alkylphosphonic acid organic ligands are selected from methylene diphosphonic acid; and the sugar organic ligands are selected from sucrose, fruit... Sugars, mannose, glucose, α-lactose; phenolic hydroxyl organic ligands selected from salicylaldehyde and its derivatives, 2,6-dihydroxymethylphenol, 2-hydroxy-4-alkoxybenzophenone; alcoholic hydroxyl organic ligands selected from 2-amino-1,3-propanediol, 4-[tris-(hydroxymethyl)methyl]pyridine, tris(hydroxymethyl)aminomethane and its derivatives; nitrogen-containing heterocyclic hydroxyl organic ligands selected from 8-hydroxyquinoline and its derivatives, hexahydroxyhexaazatriphenylnaphthalene; enol organic ligands selected from 3,4-dihydroxy-3-cyclobutene-1,2-dione.

[0034] In the embodiments of this application, the various oxygen-based organic ligands selected in this application achieve a balance between the flexibility and water stability of the coordination confinement material through the synergistic effect of the parent structure and the coordinating group.

[0035] Specifically, nitrogen heterocyclic phosphonic acid organic ligands use nitrogen heterocycles as the parent structure and phosphonic acid groups as coordinating groups. The heterocyclic skeleton can provide stable spatial support, while the multidentate phosphonic acid groups can provide abundant coordination sites to form strong coordination bonds with metal ions. At the same time, the tunable spatial orientation of the phosphonic acid groups endows the coordination confinement material with local structural flexibility.

[0036] Alkylphosphonic acid ligands (methylene bisphosphonic acid) use aliphatic chains as the parent structure and phosphonic acid groups as coordinating groups; the flexible connecting units of the aliphatic chains can endow the coordination confinement material with dynamic tunability after coordination, while the strong coordinating ability of the phosphonic acid groups ensures the water stability of the coordination confinement material.

[0037] Carbohydrate organic ligands use aliphatic rings or flexible sugar chains as the structural parent and hydroxyl groups as coordinating groups; the abundant polyhydroxy coordination sites can flexibly regulate interlayer or interchain forces through weak coordination and intramolecular hydrogen bond networks, further optimizing the overall framework flexibility of coordination confinement materials.

[0038] Phenolic hydroxyl organic ligands use an aromatic ring as the parent structure and phenolic hydroxyl groups as coordinating groups. The rigid structure of the aromatic ring ensures the basic stability of the coordination framework, the strong coordination between the phenolic hydroxyl group and metal ions enhances the bonding strength, and the conformational freedom of the aromatic ring substituents gives the coordination confinement material local structural flexibility.

[0039] Hydroxyl alcohol organic ligands use aliphatic chains as the parent structure and hydroxyl alcohols as coordinating groups. The mild coordination of hydroxyl alcohols and the torsionability of aliphatic chains endow coordination confinement materials with dynamic flexibility. In some ligands, amino groups can coordinate with hydroxyl groups to further enhance coordination stability.

[0040] Nitrogen heterocyclic hydroxyl organic ligands use nitrogen heterocycles as the parent structure and hydroxyl groups as coordinating groups. The rigid framework of nitrogen heterocycles ensures structural integrity, while the synergistic coordination of hydroxyl and nitrogen atoms enhances bonding. The tunable spatial configuration of heterocycles endows coordination-confined materials with local structural flexibility.

[0041] Enol organic ligands use cyclobutene heterocycles as the parent structure and enol hydroxyl groups as coordinating groups. The rigidity of the heterocyclic skeleton and the strong coordination of the enol hydroxyl groups together ensure the water stability of the coordination confinement material, while the conformational flexibility of the hydroxyl groups endows the coordination confinement material with local structural flexibility.

[0042] In addition, the structural parent structure of oxygen-based organic ligands can also include aromatic hydrocarbons, bridged rings, etc., and the coordinating group can also be selected from carboxyl groups, aldehyde groups, or combinations thereof to adapt to the coordination requirements of different metal ions. The structural parent structure and coordinating group characteristics of the above-mentioned types of oxygen-based organic ligands work together to ensure the structural integrity of the coordination confinement material in the water environment through strong coordination, and to endow the coordination confinement material with dynamic response capabilities in different dimensions based on its own structural flexibility, thereby effectively amplifying the diffusion difference between H2O and D2O and improving the adsorption and separation performance of water and heavy water.

[0043] As a second aspect of this application, a method for preparing a flexible water-stable coordination confinement material is provided, comprising: providing a precursor solution containing an oxygen-containing organic ligand; adding a metal precursor containing metal ions to the precursor solution; mixing evenly and then carrying out a coordination reaction; and after the reaction is completed, sequentially performing filtration, washing, drying and activation treatments to obtain the flexible water-stable coordination confinement material.

[0044] In the embodiments of this application, the preparation method provided by this application is simple in steps and controllable in process. The uniform contact between metal ions and oxygen-based organic ligands can be achieved by mixing the precursor solution, ensuring that the coordination reaction proceeds fully. The subsequent filtration and washing processes can effectively remove reaction impurities, and the drying and activation processes can further optimize the coordination environment and pore structure of the coordination confinement material, ensuring that the prepared coordination confinement material is stable and has both structural flexibility and high water stability. The overall process does not require complex equipment, is easy to operate, and is conducive to large-scale production, laying a technological foundation for the industrial application of coordination confinement materials.

[0045] In some embodiments, the molar ratio of the metal precursor to the oxygen-based organic ligand is 1:(0.06-8), for example, it can be 1:0.06, 1:0.1, 1:1, 1:3, 1:5, or 1:8.

[0046] In some embodiments, the metal precursor is selected from any one of ammonium salts, chloride salts, sulfates, and nitrates, such as ammonium metavanadate, zirconium sulfate, and copper chloride. Further selections include ammonium tetraoxonate, ammonium copper sulfate, vanadium chloride, zirconium chloride, vanadium sulfate, copper sulfate, vanadium nitrate, zirconium nitrate, and copper nitrate. These metal precursors all possess good water solubility or solvent compatibility, enabling rapid dissociation and release of the target metal ions in the precursor solution. This allows for uniform and sufficient contact with the oxygen-based organic ligands, promoting orderly coordination reactions, avoiding structural defects caused by localized over-coordination, and ensuring that the final prepared flexible water-stable coordination-confined material possesses a uniform spatial structure and stable flexibility and water stability.

[0047] In some embodiments, the reaction temperature of the coordination reaction is 20-250°C, for example, 20°C, 50°C, 100°C, 150°C, or 250°C; the reaction time of the coordination reaction is 1-96h, for example, 1h, 5h, 10h, 50h, or 96h.

[0048] In some embodiments, the drying temperature is 20-30°C, for example, 20°C, 25°C, or 30°C; the drying time is 6-24 hours, for example, 6 hours, 8 hours, 12 hours, 18 hours, or 24 hours.

[0049] In some embodiments, the activation temperature is 50-200°C, for example, 50°C, 100°C, 150°C, or 200°C; the activation time is 2-12 hours, for example, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, or 12 hours. Further, the activation is performed under vacuum conditions.

[0050] The specific activation process is as follows: The coordination confinement material after filtration, washing and drying is placed in a vacuum environment with a degree of 0.001-0.1 torr and vacuum activated at a temperature of 50-200℃ for 2-12 hours.

[0051] In some embodiments, the solvent used in the precursor solution is selected from at least one of water, alcohol, ketone, and N,N'-dimethylformamide. Alcohol solvents may include methanol, ethanol, n-propanol, isopropanol, etc.; ketone solvents may include acetone, butanone, methyl isobutyl ketone, etc. Water is used as the solvent for the washing process.

[0052] In some embodiments, the coordination reaction is carried out using a reaction method selected from hydrothermal, solvothermal, atmospheric reflux, microwave, and ultrasonic methods.

[0053] The above reaction methods are all suitable for the coordination reaction requirements of metal ions and oxygen-based organic ligands. Hydrothermal and solvothermal methods can promote the stable formation of coordination bonds through high temperature and high pressure environments. The atmospheric pressure reflux method is mild and easy to control the temperature. Microwave and ultrasonic methods can accelerate the mixing and mass transfer of the reaction system and improve the reaction efficiency. The methods can be flexibly selected according to the solubility of oxygen-based organic ligands and the reactivity of metal precursors to ensure that the coordination reaction proceeds efficiently and orderly.

[0054] For example, when the coordination reaction is carried out using a hydrothermal method, the specific preparation process of the flexible water-stable coordination confinement material is as follows:

[0055] S1: Using water as a solvent, the oxygen-based organic ligand is dispersed in it and stirred with a magnetic stir bar and a stirring table until it is uniformly dispersed; then the metal precursor is added, and the molar ratio of the metal precursor to the oxygen-based organic ligand is controlled at 1:(0.06-0.6). The mixture is stirred with a magnetic stir bar and a stirring table to obtain a uniformly mixed reaction solution.

[0056] S2: The reaction solution obtained in step S1 is subjected to a hydrothermal reaction at a temperature of 20-250℃ for a time of 24-96h.

[0057] S3: After the hydrothermal reaction is completed, a vacuum filtration device is set up to filter the obtained mixture; then, the filter residue is washed with water as a washing solvent, and after washing, it is placed in the air to dry at a temperature of 20-30℃ for 6-24 hours; finally, the dried sample is activated by vacuum heating under the following conditions: temperature 50-200℃, vacuum degree 0.001-0.1 torr, and time 2-12 hours.

[0058] For example, when the coordination reaction is carried out using the atmospheric pressure reflux method, the specific preparation process of the flexible water-stable coordination confinement material is as follows:

[0059] Q1: Using water as a solvent, disperse the oxygen-based organic ligands in it and stir with a magnetic stir bar and a stirring table until the dispersion is uniform; then add the metal precursor, controlling the molar ratio of the metal precursor to the oxygen-based organic ligands to be 1:(0.2-8), and continue stirring with a magnetic stir bar and a stirring table to obtain a uniformly mixed reaction solution.

[0060] Q2: The reaction solution obtained in step Q1 is subjected to reflux reaction at normal pressure, the reaction temperature is 60-130℃, and the reaction time is 1-72h.

[0061] Q3: After the atmospheric pressure reflux reaction is completed, a vacuum filtration device is set up to filter the obtained mixture; then, the filter residue is washed with water as a washing solvent, and after washing, it is placed in the air to dry at a temperature of 20-30℃ for 6-24 hours; finally, the dried sample is activated by vacuum heating under the following conditions: temperature 50-200℃, vacuum degree 0.001-0.1 torr, and time 2-12 hours.

[0062] As a third aspect of this application, an application of a flexible water-stable coordination confinement material in the adsorption and separation of water and heavy water is provided.

[0063] In the embodiments of this application, the flexible water-stable coordination confinement material provided by this application, with its tunable one-dimensional chain structure, two-dimensional layered structure, or three-dimensional framework structure, can amplify the slight difference in diffusion rates between H2O and D2O during the adsorption and separation of water and heavy water through the dynamic deformation of the coordination confinement material framework or the reversible contraction-expansion of the pores, thereby achieving efficient sieving of the two molecules. Simultaneously, its stable framework, constructed by strong coordination bonds between metal ions and oxygen-based organic ligands, ensures that the coordination confinement material maintains structural integrity and flexible response capabilities in an aqueous environment, avoiding structural collapse or performance degradation due to water immersion. This maintains stable separation efficiency during long-term adsorption and separation cycles, providing a structurally reliable material support for the large-scale, low-energy separation of water and heavy water.

[0064] In summary, this application provides a flexible water-stable coordination confinement material constructed from oxygen-based organic ligands, its preparation method, and its application in the adsorption and separation of water and heavy water, aiming to solve the problems of low separation factor, high energy consumption, and high cost of traditional separation methods.

[0065] This application abandons conventional ligands and specifically designs and uses simple organic ligands containing specific oxygen functional groups, such as polyhydroxyl and phosphonic acid ligands (e.g., methylene diphosphonic acid, squaric acid, etc.). These ligands have the characteristics of well-defined functions, highly predictable properties, economic availability, well-defined charge states, and tunable pore chemical environment. They are used to synthesize target coordination-confined materials through coordination reactions with metal precursors. When oxygen-based organic ligands coordinate with metal ions, pre-establish interaction sites, making the coordination-confined materials more hydrophilic and water-selective. Furthermore, the resulting structure exhibits superior chemical, thermal, and water stability compared to some conventional metal frameworks (MOFs). Comparative tests before and after water washing confirm that the structure of the coordination-confined material remains unchanged.

[0066] Meanwhile, this application achieves multi-scale flexible control from local conformation adjustment to the overall framework by selecting oxygen-based organic ligands with intrinsic structural characteristics and utilizing the free rotation of the methylene diphosphonic acid aliphatic chain and the local stretching of squaric acid oxygen atoms, breaking through the single mode of local flexibility in conventional flexible MOFs. The flexibility of the coordination-confined material originates from the intrinsic conformational freedom of the oxygen-based organic ligands, and has the characteristics of multi-scale, pre-settable, and actively controllable features. Specifically, it includes overall framework flexibility, local structural flexibility, and the synergistic flexibility of the combination of the two, which can respond to the water molecule diffusion process in real time, amplify the dynamic differences of isotope molecules, and achieve separation effects that cannot be achieved by conventional rigid or single-scale flexible materials.

[0067] The coordination confinement material provided in this application exhibits significant adsorption and separation effects on water and heavy water under both room temperature and low temperature heating conditions. Its preparation process is based on the advantages of simple ligand synthesis and features low cost and easy scalability. Compared with existing technologies, it not only solves the problems of traditional separation technologies but also provides a higher-performance isotope separation material, providing key support for the large-scale utilization of deuterium isotopes.

[0068] The present application is further illustrated below through embodiments and related test experiments. In the detailed description below, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may be implemented without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict. All instruments, consumables, and reagents used in the following embodiments are commercially available unless otherwise specified.

[0069] Example 1

[0070] This embodiment 1 provides an oxygen-based organic ligand of methylene diphosphonic acid and a metal cation of V. 4+ The specific preparation process of the coordination-confined material is as follows.

[0071] 91.75 mg of methylene diphosphonic acid (as shown in Formula 1) was dissolved in 8.55 mL of water and stirred at room temperature until the methylene diphosphonic acid was completely dissolved. Then, 117 mg of ammonium metavanadate was added, and stirring was continued to mix the system evenly. The above mixed solution was transferred to a 25 mL reaction vessel, sealed, and placed in a 170 °C oven for constant temperature reaction for 96 h. After the reaction was completed, the reaction vessel was allowed to cool naturally to room temperature, and the reaction product was taken out and collected by vacuum filtration. The obtained product was then added to deionized water at a solid-liquid ratio of 1:1 and washed at a stirring rate of 1000 r / min for 4 h. The solid was collected by vacuum filtration again. The washed product was placed in air to dry naturally, and then the dried sample was activated by vacuum heating at 80 °C for 6 h to finally obtain the coordination confinement material with methylene diphosphonic acid as a ligand (denoted as V-MDP-1).

[0072] Formula 1.

[0073] Figure 1 This is a schematic diagram of the crystal structure of V-MDP-1 in Embodiment 1 of this application.

[0074] from Figure 1 It can be seen that V-MDP-1 is composed of V 4+ It assembles with methylene diphosphonic acid via a coordination reaction to form: V 4+ As coordination nodes, they coordinate with the phosphonic acid groups of methylene diphosphonic acid, constructing two types of coordination structure units: square pyramidal and octahedral. These coordination units are interconnected through vertex sharing, ultimately forming a three-dimensional porous framework. Each phosphonic acid group contains three coordinateable oxygen atoms, and the oxygen atoms from multiple phosphonic acid groups collectively interact with V... 4+ Coordination forms two strong coordination environments: 5-coordination (quadrilateral pyramidal) and 6-coordination (octahedral), providing core support for the structural stability of the three-dimensional porous framework. Methylene diphosphonic acid is a strongly coordinating oxygen-containing organic ligand, and its structural parent is an aliphatic chain, which has intrinsic flexibility: on the one hand, the inherent conformational freedom of the aliphatic chain endows the ligand with local mobility, enabling V-MDP-1 to possess ligand-driven local structural flexibility; on the other hand, the torsion properties of the aliphatic chain can flexibly adjust the spatial orientation of the ligand, driving reversible deformation of the three-dimensional porous framework through conformational changes of the ligand, thereby enabling V-MDP-1 to simultaneously possess overall framework flexibility.

[0075] Furthermore, to investigate the structural integrity of V-MDP-1 before and after water washing, powder X-ray diffraction (PXRD) tests were performed. The PXRD data were collected using a Rigaku Miniflex diffractometer equipped with Cu Kα radiation (λ=1.54059Å) for fundamental characterization of the crystal structure of the V-MDP-1 samples.

[0076] Figure 2 This is a powder X-ray diffraction pattern of V-MDP-1 in Example 1 of this application.

[0077] from Figure 2 As can be seen, the characteristic diffraction peaks of V-MDP-1 are clear and sharp, indicating that the target flexible water-stable coordination confinement material V-MDP-1 has been successfully synthesized and possesses good crystallinity. After washing V-MDP-1 with water at a stirring speed of 1000 r / min for 4 h at a 1:1 ratio, the PXRD diffraction peak positions and intensities of the resulting sample remained highly consistent with those of the sample before washing. This result confirms that V-MDP-1 did not undergo a phase transition after prolonged water washing, and its crystallinity did not show a significant decrease, fully demonstrating the excellent room-temperature water stability of this coordination confinement material.

[0078] Furthermore, to test the adsorption performance of V-MDP-1 for water and heavy water, the following tests were conducted. Before the tests, the water solvent used in the experiments was degassed through five cycles of freezing-pumping-thawing to ensure the accuracy of the adsorption tests. Using a Belsarp Max X analyzer, single-component adsorption equilibrium isotherm data for V-MDP-1 for water and heavy water were collected at 303 K.

[0079] Figure 3 This is an adsorption separation diagram of water and heavy water of V-MDP-1 at 303K in Example 1 of this application.

[0080] from Figure 3 It can be seen that within the absolute pressure test range of 0-4 kPa, the adsorption capacity of V-MDP-1 for heavy water is consistently higher than that for water, demonstrating its inherent adsorption selectivity for heavy water molecules. Taking an absolute pressure of 3.41 kPa as an example, the adsorption capacity of V-MDP-1 for heavy water reaches 138.2 mg / g, while the adsorption capacity for water is 115.1 mg / g, with a heavy water to water adsorption ratio of 1.20. This result directly confirms that under 303 K conditions, V-MDP-1 has preferential adsorption characteristics for heavy water molecules, effectively achieving the adsorption and separation of water and heavy water.

[0081] Example 2

[0082] This embodiment 2 provides an oxygen-based organic ligand of methylene diphosphonic acid and a metal cation of V. 4+The specific preparation process of the coordination-confined material is as follows.

[0083] 53 mg of methylene diphosphonic acid was dissolved in 5 mL of water and stirred at room temperature until the methylene diphosphonic acid was completely dissolved. Then, 117 mg of ammonium metavanadate was added, and stirring continued until the system was homogeneous. The mixture was transferred to a 25 mL reactor, sealed, and placed in a 170 °C oven for 96 h. After the reaction was complete, the reactor was allowed to cool naturally to room temperature. The reaction product was then removed and collected by vacuum filtration. The resulting product was then added to deionized water at a solid-liquid ratio of 1:1 and washed at a stirring rate of 1000 r / min for 4 h. The solid was collected again by vacuum filtration. The washed product was allowed to air dry naturally, and then the dried sample was activated by vacuum heating at 80 °C for 6 h, finally yielding a coordination-confined material with methylene diphosphonic acid as the ligand (denoted as V-MDP-2).

[0084] Figure 4 This is a schematic diagram of the crystal structure of V-MDP-2 in Embodiment 2 of this application.

[0085] from Figure 4 As can be seen, similar to the construction and flexibility mechanism of V-MDP-1, V-MDP-2 also uses methylene diphosphonic acid as a strong coordinating oxygen organic ligand, and interacts with V... 4+ Metal ions assemble through coordination reactions to form V; 4+ It is 5-coordinated, with 5 coordinating oxygen atoms around the center, forming a trigonal bipyramidal coordination polyhedron. These coordination polyhedra are bridged by phosphonic oxygen atoms of the methylene bisphosphonic acid ligand, constructing an infinitely extending one-dimensional coordination chain. The chains are ordered and stacked through weak interactions, ultimately yielding the V-MDP-2 crystal. The aliphatic chain structure of methylene bisphosphonic acid possesses intrinsic conformational freedom and torsion, allowing for flexible changes in spatial orientation through local conformational adjustments. Therefore, V-MDP-2 also exhibits ligand-driven local structural flexibility.

[0086] Furthermore, to investigate the structural integrity of V-MDP-2 before and after water washing, powder X-ray diffraction (PXRD) tests were performed. The PXRD data were collected using a Rigaku Miniflex diffractometer equipped with Cu Kα radiation (λ=1.54059Å) for fundamental characterization of the crystal structure of the V-MDP-2 samples.

[0087] Figure 5 This is a powder X-ray diffraction pattern of V-MDP-2 in Example 2 of this application.

[0088] from Figure 5As can be seen, the characteristic diffraction peaks of V-MDP-2 are sharp and significant, indicating that the target flexible water-stable coordination confinement material V-MDP-2 has been successfully synthesized and possesses good crystallinity. After washing V-MDP-2 with water at a stirring speed of 1000 r / min for 4 h at a 1:1 ratio, the PXRD diffraction peak positions, peak shapes, and intensities of the resulting sample remained highly consistent with those of the sample before washing. This result confirms that V-MDP-2 did not undergo a phase transition after prolonged water washing, and its crystallinity did not show a significant decrease, fully demonstrating the excellent room-temperature water stability of this coordination confinement material.

[0089] Furthermore, to test the adsorption performance of V-MDP-2 for water and heavy water, the following tests were conducted. Before the tests, the water solvent used in the experiments was degassed through five cycles of freezing-pumping-thawing to ensure the accuracy of the adsorption tests. Using a Belsarp Max X analyzer, single-component adsorption equilibrium isotherm data for V-MDP-2 for water and heavy water were collected at 303 K.

[0090] Figure 6 This is an adsorption separation diagram of water and heavy water of V-MDP-2 at 303K in Example 2 of this application.

[0091] from Figure 6 It can be seen that within the absolute pressure test range of 0-4 kPa, the adsorption capacity of V-MDP-2 for water is significantly higher than that for heavy water throughout the test, exhibiting inherent adsorption selectivity for water molecules. Taking an absolute pressure of 3.38 kPa as an example, the adsorption capacity of V-MDP-2 for water reaches 220.2 mg / g, while the adsorption capacity for heavy water is 115.5 mg / g, with a water to heavy water adsorption ratio of 1.91. This result directly confirms that under 303 K conditions, V-MDP-2 has preferential adsorption characteristics for water molecules, effectively achieving the adsorption and separation of water and heavy water.

[0092] Example 3

[0093] This embodiment 3 provides an example where the oxygen-based organic ligand is squaric acid and the metal cation is Zr. 4+ The specific preparation process of the coordination-confined material is as follows.

[0094] 2280 mg of squaric acid (as shown in Formula 2) was dissolved in 10 mL of water and sonicated at room temperature to obtain a clear and transparent solution. Then, 3550 mg of zirconium sulfate was added, and the mixture was transferred to a 25 mL flask. The flask was placed on a pre-built reflux apparatus and refluxed at 60 °C for 24 h. After the reaction was complete, the flask was allowed to cool naturally to room temperature. The reaction product was then removed from the flask and collected by vacuum filtration. The resulting product was then added to deionized water at a solid-liquid ratio of 1:1 and washed at a stirring rate of 1000 r / min for 4 h. The solid was collected by vacuum filtration again. The washed product was allowed to air dry naturally, and then the dried sample was activated by vacuum heating at 50 °C for 6 h, finally yielding a coordination-confined material with squaric acid as a ligand (denoted as Zr-SA-1).

[0095] Equation 2.

[0096] Figure 7 This is a schematic diagram of the crystal structure of Zr-SA-1 in Embodiment 3 of this application.

[0097] from Figure 7 It can be seen that Zr-SA-1 is composed of Zr 4+ The structure is constructed from metal ions and squaric acid organic ligands: each Zr atom adopts an eight-coordinate mode, and four Zr atoms aggregate to form Zr4 cluster secondary structural units; squaric acid, as a hydroxyl-containing organic ligand, bridges adjacent Zr4 clusters through its oxygen atoms, ultimately constructing a regular two-dimensional layered structure. As a simple oxygen-based organic ligand, squaric acid possesses potential local rotational and stretching conformational freedom, making the Zr-SA-1 formed by its coordination primarily characterized by ligand-driven local structural flexibility, accompanied by weak overall framework flexibility.

[0098] Furthermore, to investigate the structural integrity of Zr-SA-1 before and after water washing, powder X-ray diffraction (PXRD) tests were performed. The PXRD data were collected using a Rigaku Miniflex diffractometer equipped with Cu Kα radiation (λ=1.54059Å) for fundamental characterization of the crystal structure of the Zr-SA-1 samples.

[0099] Figure 8 This is a powder X-ray diffraction pattern of Zr-SA-1 in Example 3 of this application.

[0100] from Figure 8As can be seen, the characteristic diffraction peaks of Zr-SA-1 are sharp and significant, indicating that the target flexible water-stable coordination confinement material Zr-SA-1 has been successfully synthesized and possesses good crystallinity. After washing Zr-SA-1 with water at a stirring speed of 1000 r / min for 4 h at a 1:1 ratio, the PXRD diffraction peak positions, peak shapes, and intensities of the resulting sample remained highly consistent with those of the sample before washing. This result confirms that Zr-SA-1 did not undergo a phase transition after prolonged water washing, and its crystallinity did not show a significant decrease, fully demonstrating the excellent room-temperature water stability of this coordination confinement material.

[0101] Furthermore, to test the adsorption performance of Zr-SA-1 for water and heavy water, the following tests were conducted. Before the tests, the water solvent used in the experiments was degassed through five cycles of freezing-pumping-thawing to ensure the accuracy of the adsorption tests. Using a Belsarp Max X analyzer, single-component adsorption equilibrium isotherm data for Zr-SA-1 for water and heavy water were collected at 303 K.

[0102] Figure 9 This is a diagram showing the adsorption and separation of water and heavy water in Zr-SA-1 at 303K in Example 3 of this application.

[0103] from Figure 9 It can be seen that within the absolute pressure test range of 0-4 kPa, the adsorption capacity of Zr-SA-1 for water is consistently higher than that for heavy water, demonstrating its inherent adsorption selectivity for water molecules. Taking an absolute pressure of 3.61 kPa as an example, the adsorption capacity of Zr-SA-1 for water reaches 137.2 mg / g, while the adsorption capacity for heavy water is 93.1 mg / g, with a water to heavy water adsorption ratio of 1.47. This result directly confirms that Zr-SA-1 synthesized by the reflux method at 303 K exhibits preferential adsorption characteristics for water molecules, effectively achieving the adsorption and separation of water and heavy water.

[0104] Example 4

[0105] This embodiment 4 provides an example where the oxygen-based organic ligand is squaric acid and the metal cation is Zr. 4+ The specific preparation process of the coordination-confined material is as follows.

[0106] 228 mg of squaric acid was dissolved in 1 mL of water and stirred at room temperature until the squaric acid was completely dissolved. Then, 355 mg of zirconium sulfate was added, and stirring was continued until the system was homogeneous. The above mixed solution was transferred to a 25 mL reaction vessel, sealed, and placed in a 60 °C oven for 72 h of constant temperature reaction. After the reaction was completed, the reaction vessel was allowed to cool naturally to room temperature, and the reaction product was removed and collected by vacuum filtration. The obtained product was then added to deionized water at a solid-liquid ratio of 1:1 and washed at a stirring rate of 1000 r / min for 4 h. The solid was collected by vacuum filtration again. The washed product was placed in air to dry naturally, and then the dried sample was activated by vacuum heating at 50 °C for 6 h to finally obtain the coordination confinement material with squaric acid as a ligand (denoted as Zr-SA-2).

[0107] Crystal structure characterization confirmed that the crystal structure of Zr-SA-2 prepared in Example 4 is consistent with that of Zr-SA-1 in Example 3.

[0108] Furthermore, to investigate the structural integrity of Zr-SA-2 before and after water washing, powder X-ray diffraction (PXRD) tests were performed. The PXRD data were collected using a Rigaku Miniflex diffractometer equipped with Cu Kα radiation (λ=1.54059Å) for fundamental characterization of the crystal structure of the Zr-SA-2 samples.

[0109] Figure 10 This is a powder X-ray diffraction pattern of Zr-SA-2 in Example 4 of this application.

[0110] from Figure 10 As can be seen, the characteristic diffraction peaks of Zr-SA-2 are sharp and significant, indicating that the target flexible water-stable coordination confinement material Zr-SA-2 has been successfully synthesized and possesses good crystallinity. After washing Zr-SA-2 with water at a stirring speed of 1000 r / min for 4 h at a 1:1 ratio, the PXRD diffraction peak positions, peak shapes, and intensities of the resulting sample remained highly consistent with those of the sample before washing. This result confirms that Zr-SA-2 did not undergo a phase transition after prolonged water washing, and its crystallinity did not show a significant decrease, fully demonstrating the excellent room-temperature water stability of this coordination confinement material.

[0111] Furthermore, to test the adsorption performance of Zr-SA-2 for water and heavy water, the following tests were conducted. Before the tests, the water solvent used in the experiments was degassed through five cycles of freezing-pumping-thawing to ensure the accuracy of the adsorption tests. Using a Belsarp Max X analyzer, single-component adsorption equilibrium isotherm data for Zr-SA-2 for water and heavy water were collected at 303 K.

[0112] Figure 11This is a diagram showing the adsorption and separation of water and heavy water in Zr-SA-2 at 303K in Example 4 of this application.

[0113] from Figure 11 It can be seen that within the absolute pressure test range of 0-4 kPa, the adsorption capacity of Zr-SA-2 for heavy water is consistently higher than that for water, exhibiting an inherent adsorption selectivity for heavy water molecules. Taking an absolute pressure of 3.44 kPa as an example, the adsorption capacity of Zr-SA-2 for heavy water reaches 189.2 mg / g, while the adsorption capacity for water is 130.4 mg / g, with a heavy water to water adsorption ratio of 1.45. This result directly confirms that, under 303 K conditions, Zr-SA-2 synthesized via a hydrothermal method has preferential adsorption characteristics for heavy water molecules, effectively achieving the adsorption and separation of water and heavy water.

[0114] Example 5

[0115] This embodiment 5 provides an oxygen-based organic ligand of methylene diphosphonic acid and a metal cation of Cu. 2+ The specific preparation process of the coordination-confined material is as follows.

[0116] 489 mg of methylene diphosphonic acid was dissolved in 5 mL of water and stirred at room temperature until the methylene diphosphonic acid was completely dissolved. Then, 472 mg of copper chloride dihydrate was added, and stirring continued until the system was homogeneous. The mixture was transferred to a 25 mL reaction vessel, sealed, and placed in a 120 °C oven for 48 h. After the reaction was complete, the reaction vessel was allowed to cool naturally to room temperature. The reaction product was then removed and collected by vacuum filtration. The resulting product was then added to deionized water at a solid-liquid ratio of 1:1 and washed at a stirring rate of 1000 r / min for 4 h. The solid was collected again by vacuum filtration. The washed product was allowed to air dry naturally, and then the dried sample was activated by vacuum heating at 80 °C for 6 h, finally yielding a coordination-confined material with methylene diphosphonic acid as the ligand (denoted as Cu-MDP).

[0117] Figure 12 This is a schematic diagram of the crystal structure of Cu-MDP in Example 5 of this application.

[0118] from Figure 12 It can be seen that Cu-MDP exhibits a two-dimensional layered structure, in which Cu 2+Two coordination environments exist: octahedral coordination (coordination number 6) and trigonal bipyramidal coordination (coordination number 5). The hexamer structure constructed by the trigonal bipyramidal coordination units is connected to the isolated octahedral coordination units through phosphonic oxygen atoms of methylene bisphosphonic acid, forming a continuous two-dimensional layered structure. Similar to the flexibility mechanism of V-MDP-1, Cu-MDP also uses methylene bisphosphonic acid as a strong coordinating oxygen-containing organic ligand. The aliphatic chain structure of the ligand has intrinsic conformational freedom, enabling the coordination-confined material to possess ligand-driven local structural flexibility. At the same time, due to the constraints of the two-dimensional layered structure and the strong intralayer coordination bonds, Cu-MDP exhibits weak overall framework flexibility.

[0119] Furthermore, to investigate the structural integrity of Cu-MDP before and after water washing, powder X-ray diffraction (PXRD) tests were performed. The PXRD data were collected using a Rigaku Miniflex diffractometer equipped with Cu Kα radiation (λ=1.54059Å) for fundamental characterization of the crystal structure of the Cu-MDP samples.

[0120] Figure 13 This is a powder X-ray diffraction pattern of Cu-MDP in Example 5 of this application.

[0121] from Figure 13 As can be seen, the characteristic diffraction peaks of Cu-MDP are sharp and significantly intense, indicating that the target flexible water-stable coordination confinement material Cu-MDP with methylene diphosphonic acid as a ligand has been successfully synthesized and possesses good crystallinity. After washing Cu-MDP with water at a stirring speed of 1000 r / min and a 1:1 ratio for 4 h, the PXRD diffraction peak positions, peak shapes, and intensities of the obtained sample remained highly consistent with those of the sample before washing. This result confirms that Cu-MDP did not undergo a phase transition after prolonged water washing, and its crystallinity did not decrease significantly, fully demonstrating the excellent room-temperature water stability of this coordination confinement material.

[0122] Furthermore, to test the adsorption performance of Cu-MDP on water and heavy water, the following tests were conducted. Before the tests, the water solvent used in the experiments was degassed through five cycles of freezing-pumping-thawing to ensure the accuracy of the adsorption tests. Using a Belsarp Max X analyzer, single-component adsorption equilibrium isotherm data for Cu-MDP on water and heavy water were collected at 303 K.

[0123] Figure 14 This is an adsorption separation diagram of water and heavy water in Cu-MDP at 303K in Example 5 of this application.

[0124] from Figure 14It can be seen that within the absolute pressure test range of 0-4 kPa, the adsorption capacity of Cu-MDP for heavy water is consistently higher than that for water, demonstrating its inherent adsorption selectivity for heavy water molecules. Taking an absolute pressure of 3.49 kPa as an example, the adsorption capacity of Cu-MDP for heavy water reaches 143.5 mg / g, while the adsorption capacity for water is 108.0 mg / g, with a heavy water to water adsorption ratio of 1.33. This result directly confirms that under 303 K conditions, Cu-MDP has preferential adsorption characteristics for heavy water molecules, effectively achieving the adsorption and separation of water and heavy water.

[0125] As can be seen from the above embodiments, the coordination confinement materials provided in this application all possess the adsorption capacity for water (H2O) and heavy water (D2O) under 303K conditions. Comparative analysis of Examples 1, 2, and 5 shows that this application can construct coordination confinement materials with different structures using the same oxygen-based organic ligand, exhibiting significant differences in structural flexibility. This difference in structural flexibility leads to differences in the diffusion efficiency of water and heavy water molecules within the pores, and also drives reversible conformational changes in the coordination confinement materials within the pores, thereby regulating the hydrophilicity and hydrophobicity of the pores. Ultimately, this results in different adsorption selectivity for water and heavy water in coordination confinement materials with different structures.

[0126] The coordination-confined materials provided in this application are all constructed from simple, strongly coordinating oxygen-based organic ligands. These ligands possess structural advantages such as well-defined geometric configurations, strong structural predictability, rich coordination modes, and excellent bonding ability with metal ions, providing ideal structural building blocks for constructing coordination-confined materials that simultaneously exhibit excellent structural flexibility and high water stability. All coordination-confined materials in Examples 1 to 5 demonstrate excellent room-temperature water stability. This characteristic effectively ensures the structural integrity of the coordination-confined materials in an aqueous environment, while also ensuring the stability and reliability of the water and heavy water adsorption regulation mechanisms.

[0127] In summary, this application provides a coordination confinement material that combines excellent structural flexibility with high water stability. These coordination confinement materials are all efficiently constructed from simple, strongly coordinating oxygen-based organic ligands, exhibiting excellent application performance in the adsorption and separation of water and heavy water, and providing a novel material solution for the large-scale separation of deuterium isotopes.

[0128] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are 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 protection scope of this application.

Claims

1. A flexible water-stabilized coordination confinement material, characterized in that, The flexible water-stable coordination confinement material is obtained by coordination reaction of metal ions and oxygen-based organic ligands. Wherein, the metal ions are selected from V 4+ Zr 4+ Cu 2+ Ti 4+ Al 3+ Cr 3+ Fe 3+ Any one of them; The oxygen-containing organic ligand is selected from any one of the following: nitrogen-containing heterocyclic phosphonic acid organic ligands, alkyl phosphonic acid organic ligands, sugar organic ligands, phenolic hydroxyl organic ligands, alcoholic hydroxyl organic ligands, nitrogen-containing heterocyclic hydroxyl organic ligands, and enol organic ligands.

2. The flexible water-stabilized coordination confinement material according to claim 1, characterized in that, The flexible water-stable coordination confinement material is a one-dimensional chain structure, a two-dimensional layered structure, or a three-dimensional framework structure formed by the metal ions and the oxygen-based organic ligands connected by coordination bonds. The coordination number of the metal ions in the flexible water-stable coordination confinement material is 1-8.

3. The flexible water-stabilized coordination confinement material according to claim 1, characterized in that, The azacyclic phosphonic acid organic ligands are selected from (piperazine-1,4-diylbis(methylene))bis(phosphonic acid), (1,4-diazacycloheptane-1,4-diylbis(methylene))bis(phosphonic acid), (S)-2-methyl-1,4-bis(phosphonomethyl)piperazine, 1,4-bis(phosphonomethyl)-2,5-piperazinedione, and 1,4,7-triazacyclononane-1,4,7-tris(methylenephosphonic acid); The alkylphosphonic acid organic ligand is selected from methylene diphosphonic acid; The sugar organic ligands are selected from sucrose, fructose, mannose, glucose, and α-lactose; The phenolic hydroxyl organic ligands are selected from salicylaldehyde and its derivatives, 2,6-dihydroxymethylphenol, and 2-hydroxy-4-alkoxybenzophenone. The hydroxyl organic ligands are selected from 2-amino-1,3-propanediol, 4-[tris-(hydroxymethyl)methyl]pyridine, tris(hydroxymethyl)aminomethane and their derivatives; The nitrogen-containing heterocyclic hydroxyl organic ligands are selected from 8-hydroxyquinoline and its derivatives, and hexahydroxyhexaazatriphenylnaphthalene; The enol organic ligands are selected from 3,4-dihydroxy-3-cyclobutene-1,2-dione.

4. A method for preparing a flexible water-stabilized coordination confinement material as described in any one of claims 1-3, characterized in that, include: A precursor solution containing an oxygen-containing organic ligand is provided. A metal precursor containing metal ions is added to the precursor solution, and after mixing evenly, a coordination reaction is carried out. After the reaction is completed, the material is sequentially filtered, washed, dried, and activated to obtain a flexible water-stable coordination confinement material.

5. The preparation method according to claim 4, characterized in that, The molar ratio of the metal precursor to the oxygen-based organic ligand is 1:(0.06-8).

6. The preparation method according to claim 4, characterized in that, The metal precursor is selected from any one of ammonium salts, chloride salts, sulfates, and nitrates.

7. The preparation method according to claim 4, characterized in that, The coordination reaction is carried out at a temperature of 20-250℃ and for a time of 1-96h.

8. The preparation method according to claim 4, characterized in that, The drying temperature is 20-30℃, and the drying time is 6-24 hours. The activation treatment temperature is 50-200℃, and the activation treatment time is 2-12h; The activation process is carried out under vacuum conditions.

9. The preparation method according to claim 4, characterized in that, The solvent used in the precursor solution is selected from at least one of water, alcohol, ketone, and N,N'-dimethylformamide; The solvent used in the washing process is water.

10. The application of a flexible water-stabilized coordination confinement material as described in any one of claims 1-3 in the adsorption and separation of water and heavy water.

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