A porous coordination polymer and preparation and utilization thereof for realizing molecular recognition selectivity by temperature switching

Abstract

The present application relates to a kind of porous coordination polymers with molecular recognition selectivity by temperature change switching and its preparation method and application, belong to functional porous material field.The present application provides a kind of porous coordination polymers, the organic ligand and metal ion shown in formula I are self-assembled into porous coordination polymers by coordination bond;In formula I, R1-R8 are independently selected from one of -H, -CH3, -C2H5, -OCH3.The present application is self-assembled by the organic ligand of specific structure and metal ion by coordination bond and is obtained a kind of ultra-microporous local flexible porous polymer material;The diffusion process of the obtained porous polymer can accurately control carbon dioxide and acetylene C2H2, and amplify their diffusion rate difference;So that the material can recognize and adsorb carbon dioxide at low temperature, recognize and adsorb acetylene C2H2 at high temperature, therefore can be used in carbon dioxide and acetylene recognition inversion adsorption separation.

Description

Technical Field

[0001] This invention relates to a porous coordination polymer with molecular recognition selectivity that can be switched by temperature change, its preparation method and application, belonging to the field of functional porous materials. Background Technology

[0002] Molecular recognition plays a crucial role in supramolecular chemistry. The recognition process is essentially a process of mutual binding through the synergistic interaction of intermolecular forces under specific conditions. This reveals three important components of the molecular recognition principle: "specific conditions" refer to the need for molecules to achieve a complementary state through pre-organization; "intermolecular forces" refer to the non-covalent interactions between molecules; and "synergistic interaction" emphasizes the need for macrocyclic or chelation effects to ensure a consistent effect among various interactions. While identifying the guest with the highest affinity from multiple guest systems is generally achievable, the specific recognition of different guests under different environmental conditions remains a challenge. It is well known that for a given host-guest system, the host-guest interaction forces are definite. In other words, thermodynamically, changing the temperature cannot switch the molecular recognition selectivity. Therefore, "switching molecular recognition selectivity at different temperatures" is widely recognized as a fundamental scientific challenge in this field.

[0003] On the other hand, within the same system, changing only a single factor to switch the selectivity of recognition between different guests is crucial. Such "intelligent" host-guest materials can be widely applied in molecular machines, sensors, gas separation, and drug delivery. To achieve switchable molecular recognition, chemists have attempted to develop stimulus-responsive materials (through light, pH, and redox reactions) whose chemical structure or molecular conformation changes with external stimuli, thereby altering the host-guest interactions and achieving selective switching of molecular recognition under different conditions. However, this strategy is limited to cyclodextrin-azobenzene, cyclodextrin-benzimidazole, and cyclodextrin-ferrocene systems. Currently, there are no reports, either domestically or internationally, of overcoming thermodynamic limitations to achieve selective switching of molecular recognition. Summary of the Invention

[0004] The purpose of this invention is to propose a porous material with temperature-responsive molecular recognition selectivity. An ultramicroporous, locally flexible porous polymer material is prepared by self-assembling an organic ligand containing a specific structure of oxyphenthiazide and metal ions through coordination bonds. The resulting porous polymer possesses a special pore structure and folding units with folding motion, enabling precise control of the diffusion process of carbon dioxide and acetylene (C2H2) and amplifying their diffusion rate differences. This allows the material to recognize and adsorb carbon dioxide at low temperatures and acetylene (C2H2) at high temperatures, with separation factors of 498.1 (carbon dioxide / acetylene) and 180.7 (acetylene / carbon dioxide), respectively. In other words, the coordination polymer obtained by this invention exhibits temperature-responsive reverse recognition behavior and can be used for the recognition-reverse adsorption separation of carbon dioxide and acetylene.

[0005] The technical solution of the present invention:

[0006] The first technical problem to be solved by the present invention is to provide a porous coordination polymer, wherein the coordination polymer is self-assembled by organic ligands and metal ions represented by Formula I through coordination bonds;

[0007]

[0008] In Formula I, R1 to R8 are each independently selected from -H, -CH3, -C2H5, and -OCH3; Y is selected from one of the following groups:

[0009]

[0010] Furthermore, the organic ligand is selected from one of the following substances:

[0011]

[0012]

[0013] Furthermore, the dihedral angle of the two benzene rings of the organic ligand is 0–90°, and its energy barrier requires only 0–30 kJ / mol. -1 .

[0014] Furthermore, the folding motion temperature of the organic ligand is 80–400 K.

[0015] Furthermore, the metal ion is selected from one of zinc, cobalt, nickel, copper, sodium, potassium, or calcium.

[0016] Furthermore, the metal ions are derived from soluble metal salts, including nitrates, acetates, sulfates, or chlorides of metal ions, such as Zn(NO3)2·6H2O.

[0017] Furthermore, the pore size of the porous coordination polymer is...

[0018] Furthermore, the porous coordination polymer adsorbs CO2 in the range of 200–280 K and selectively adsorbs C2H2 in the range of 290–370 K.

[0019] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned porous coordination polymer, wherein the preparation method is as follows: the organic ligand of Formula I is self-assembled with a salt containing metal ions through coordination bonds.

[0020] Furthermore, the porous coordination polymer can be prepared by the following method: reacting the organic ligand of Formula I with a salt containing metal ions and a mixed solvent at 40–120°C (preferably 80°C) for 12–72 h (preferably 24 h); wherein the organic ligand accounts for 1–50% of the molar ratio of the metal ions; the mixed solvent is at least two of acetone, MeCN, DMSO, THF, DMA, DMF, DMI, NMP, EtOH, MeOH, or H2O; a mixed solvent of DMA and MeOH is preferred. When two solvents are selected as the mixed solvent, the volume ratio of the two solvents is 1 / 9 to 9 / 1 (preferably 1 / 4).

[0021] Furthermore, the organic ligand can be prepared in the following manner:

[0022] First use compound 1 and compound 2 Compound 3 was prepared Then, compound 4 was prepared using compound 3. Finally, the organic ligand shown in Formula I was prepared using compound 4.

[0023] Furthermore, the organic ligand can be prepared by the following method:

[0024] 1) Compound 1 Compound 2 Palladium acetate and cesium carbonate reacted under nitrogen or inert gas protection; the reaction was stopped when compound 1 was completely eliminated and the mixture was cooled to room temperature. Ethyl acetate and diatomaceous earth were added, and the mixture was stirred before filtering off the solid. The organic phase was extracted; the organic phase was collected and subjected to column chromatography and drying to obtain compound 3.

[0025] 2) Compound 3 was dissolved in an organic solvent, and then hydrogen peroxide solution was added to react. When compound 3 was completely dissolved, the reaction was stopped and cooled to room temperature. The organic solvent was then removed, and the organic phase was extracted. The organic phase was collected, separated by column chromatography, and dried to obtain compound 4.

[0026] 3) After dissolving compound 4 in an organic solvent, an alkaline aqueous solution was added and refluxed. After cooling to room temperature, the organic solvent was removed, the pH of the solution was adjusted, the solid was filtered out, washed and dried to obtain the organic ligand described in Formula I.

[0027] Furthermore, in step 1) above, the solvent is either ultra-dry toluene or ultra-dry p-xylene.

[0028] Furthermore, in step 1) above, the reaction is carried out at 100–120°C for 16–72 hours.

[0029] Furthermore, in steps 1) to 2) above, thin-layer chromatography is used to monitor the reaction.

[0030] Furthermore, in step 2) above, the reaction is carried out at 60–100°C for 24–48 hours.

[0031] Furthermore, in steps 2) and 3) above, the organic solvent is selected from at least one of DCM, AcOH, THF, EA, PE, MeOH or MeCN.

[0032] Furthermore, in step 3) above, the pH of the solution is adjusted to 1-2.

[0033] Furthermore, compound 1 can be prepared by the following method: [The following text appears to be a separate, unrelated section:] ...raw material... (10H-phenothiazine), halogenated aromatic compounds (such as 1,3,5-tribromobenzene), tetrakis(triphenylphosphine)palladium(O), and a base (sodium carbonate) were placed in a container. Solvent was added under nitrogen or inert gas protection, and the mixture was stirred at 100–120 °C for 12–72 h. The reaction was stopped when the halogenated aromatic compounds completely disappeared, and the mixture was cooled to room temperature. Ethyl acetate and diatomaceous earth were added, and the mixture was stirred. The solid was filtered off, and the organic phase was extracted. The organic phase was collected, separated by column chromatography, and dried to obtain compound 1. Where X is a halogen atom.

[0034] In the preparation of the organic ligands of the present invention, the preparation method and conditions of the applicant's previous work CN115558121B can be referred to.

[0035] The third technical problem to be solved by the present invention is to point out the application of the above-mentioned porous coordination polymer in the selective separation of CO2 and C2H2.

[0036] Furthermore, the porous coordination polymer is separated at a temperature of 200–370 K.

[0037] Furthermore, the porous coordination polymer adsorbs CO2 at 200–280 K, while selectively adsorbing C2H2 in the opposite range of 290–370 K.

[0038] Furthermore, the porous coordination polymer needs to be activated before use. Conventional activation methods can be used.

[0039] The beneficial effects of this invention are:

[0040] This invention provides a novel porous coordination polymer material with a special pore structure and folding units with folding motion, enabling precise control of the diffusion process of carbon dioxide and acetylene (C2H2) and amplifying their diffusion rate differences. This allows the material to recognize and adsorb carbon dioxide at low temperatures and C2H2 at high temperatures, with separation factors of 498.1 (carbon dioxide / acetylene) and 180.7 (acetylene / carbon dioxide), respectively. In other words, the coordination polymer obtained by this invention exhibits temperature-responsive reverse recognition behavior, which can be used for the recognition-reverse adsorption separation of carbon dioxide and acetylene. This is also the first time that thermodynamic limitations have been overcome to achieve selective switching of molecular recognition. Attached Figure Description

[0041] Figure 1 The organic ligand initially synthesized in Example 1 and the FDC-3 after solvent exchange in Example 2 were digested with deuterated hydrochloric acid. 1 H NMR spectrum.

[0042] Figure 2 This is the folding motion potential energy curve of the OPTz ring in the organic ligand of Example 1 of the present invention.

[0043] Figure 3 The isobaric lines of CO2 and C2H2 adsorption at 1 bar for FDC-3a in Example 2 of the present invention, and the ratios of CO2 / C2H2 and C2H2 / CO2 adsorption amounts.

[0044] Figure 4 The McCabe-Tiller diagrams for the separation of CO2 / C2H2 by FDC-3a at 240 and 320 K in Example 2 of this invention are shown below. Figure 4 a) and the correlation between CO2 concentration and the CO2 / C2H2 separation coefficient ( Figure 4 b). Detailed Implementation

[0045] This invention provides a porous material with selective molecular recognition that switches through temperature changes, and its preparation method. Specifically, a novel coordination porous polymer material is synthesized by using a specific organic ligand (locally flexible ligand) with a folding motion structure and metal ions under solvothermal conditions. In this invention, the obtained locally flexible ligand (such as an organic ligand containing phenthiazine units) exhibits in-situ vibrations and rotations with temperature-responsive characteristics, flapping and vibrating like a butterfly. The dihedral angles of the two benzene rings can undergo effective bending vibrations, with an energy barrier of 25 kJ / mol. -1It can occur effectively at very low temperatures, and the amplitude of bending vibration increases with increasing temperature, thereby achieving the purpose of precisely controlling the size of the channel outlet.

[0046] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0047] Example 1 Organic Ligands Preparation

[0048] The synthetic route for the organic ligand in Example 1 is as follows:

[0049]

[0050] The specific preparation process is as follows:

[0051] 10H-phenathiazide (4.38 g, 22.0 mmol, 2.2 eq.), 1,3,5-tribromobenzene (3.15 g, 10.0 mmol, 1.0 eq.), tetrakis(triphenylphosphine)palladium(0)(Pd(PPh3)4, 0.58 g, 0.5 mmol, 0.05 eq.), and sodium carbonate (2.65 g, 25.0 mmol, 2.5 eq.) were placed in a 250 mL round-bottom flask. The air in the flask was purged and filled with nitrogen. Under nitrogen protection, 80 mL of ultra-dry toluene was added, and the mixture was stirred at 115 °C for 24 h. The reaction was monitored by thin-layer chromatography (TLC). When the starting material 1,3,5-tribromobenzene had completely disappeared, the reaction was stopped and cooled to room temperature. 50 mL of ethyl acetate and diatomaceous earth were added to the flask, and the mixture was stirred and the solid was filtered off. The organic phase was extracted with ethyl acetate (100 mL × 3 times) and saturated brine (100 mL × 3 times). The organic phase was collected, dried with anhydrous magnesium sulfate, and then evaporated to dryness before being loaded onto a column for separation by column chromatography. The sample was dried under vacuum at 80°C for 12 hours to obtain powder (1). 2.86g, yield 66%.

[0052] Raw material 1 (2.17g, 5.0mmol, 1.0eq.), Raw material 2 (2.89 g, 5.5 mmol, 1.1 eq.), palladium acetate (Pd(OAc)2, 0.056 g, 0.25 mmol, 0.05 eq.) and cesium carbonate (4.07 g, 12.5 mmol, 2.5 eq.) were placed in a 250 ml round-bottom flask. The air in the flask was purged and filled with nitrogen. Under nitrogen protection, 80 mL of ultra-dry p-xylene was added, and the mixture was stirred at 115 °C for 16 h. The reaction was monitored by TLC. When the starting material 1 was completely eliminated, the reaction was stopped and cooled to room temperature. 50 mL of ethyl acetate and diatomaceous earth were added to the flask. After stirring, the solid was filtered off. The organic phase was extracted with ethyl acetate (100 mL × 3 times) and saturated brine (100 mL × 3 times). The organic phase was collected, dried with anhydrous magnesium sulfate, and then evaporated to dryness before being loaded onto a column for separation. The sample was dried under vacuum at 80 °C for 12 h to obtain a pale yellow powder (3). 1.98g, yield 73%.

[0053] Containing raw material 3 (1.8 g, 3.3 mmol) of DCM / AcOH (100 mL, 1 / 3 v / v) solution was added to a 250 mL round-bottom flask, followed by hydrogen peroxide solution. The reaction was carried out at 80 °C for 24 h. The reaction was monitored by TLC. When the starting material 3 was completely eliminated, the reaction was stopped and cooled to room temperature. The organic solvent was removed by rotary evaporation. The organic phase was extracted with ethyl acetate (100 mL × 3 times) and saturated brine (100 mL × 3 times). The organic phase was collected, dried with anhydrous magnesium sulfate, and then evaporated to dryness before being loaded onto a column for separation by column chromatography. The sample was dried under vacuum at 80 °C for 12 h to obtain a pale yellow powder (4). 1.67g, yield 88%.

[0054] Containing raw material 4 A THF solution of 1.6 g (2.78 mmol) (60 mL) was added to a 250 mL round-bottom flask, followed by the addition of 2 M NaOH aqueous solution (100 mL, 200 mmol). The mixture was refluxed for 16 h. After cooling to room temperature, the organic solvent was removed by rotary evaporation. The pH of the solution was adjusted to 1-2 with 3% glacial hydrochloric acid. The solid was filtered off and washed three times with deionized water. The solid was dried under vacuum at 60 °C for 12 h to obtain a white powder, OPTz-t3da (1.28 g, 84% yield).

[0055] Figure 1 The figure shows the NMR spectrum of the obtained organic ligand. As can be seen from the figure, the ligand peaks confirm the successful synthesis of the ligand. This ligand possesses a very low folding energy barrier (…). Figure 2 It can occur effectively at very low temperatures, and the amplitude of bending vibration increases with increasing temperature, thereby achieving the purpose of precisely controlling the size of the channel outlet.

[0056] Example 2: Preparation of porous coordination polymers

[0057] The 50 mg (0.09 mmol) obtained in Example 1 was subjected to treatment at 30°C. (denoted as OPTz-t3da) was dissolved in 2 mL of DMA, and then 54 mg (0.18 mmol) of Zn(NO3)2·6H2O methanol solution (8 mL) was added. The mixture was heated in an oven at 80 °C for 72 h to obtain colorless blocky single crystals with a size close to several hundred micrometers. The crystals were filtered, washed three times with DMA and methanol respectively, and dried at 30 °C to obtain the corresponding product, denoted as FDC-3 (37 mg, yield 43%).

[0058] Application Example 1

[0059] 1. Solvent exchange and activation of FDC-3

[0060] After the single crystal preparation was completed, FDC-3 underwent solvent exchange in a low-boiling-point solvent to remove the high-boiling-point solvent from the channels. Specifically, FDC-3 was immersed in anhydrous methanol at 60°C for 7 days, with a fresh batch of methanol solution every 12 hours. After the exchange was completed, a small amount of FDC-3 was placed in a 2mL vial, one drop of deuterated hydrochloric acid was added and sonicated for 1 minute, and then 1mL of deuterated dimethyl sulfoxide was added to completely dissolve the mixture and proceed with the process. 1 H NMR characterization. Test results are as follows: Figure 1 As shown, DMA in FDC-3 is completely exchanged out by methanol to obtain the activated state FDC-3a.

[0061] Figure 2 The folding energy barrier and dihedral angle (C) in the ligand were calculated. 1 -NSC 2 The potential energy curves from 120° to 200° show that the energy change (ΔE) of the OPTz ring folding motion is not significant, with ΔE less than 25 kJ / mol relative to the 25° dihedral angle. -1 The folding motion of the OPTz ring can occur effectively at very low temperatures, and the amplitude of the folding motion increases with increasing temperature.

[0062] 2. Adsorption behavior of FDC-3a and kinetics of the adsorption process:

[0063] Taking CO2 as an example, when the temperature increases from 200K to 240K, the CO2 adsorption capacity increases from 25mL / g. -1 Increase to 41 mL g -1 Then, as the temperature further increased to 370K, the adsorption amount decreased to 5 mL g. -1 Therefore, the maximum adsorption capacity of CO2 (T) max At a temperature of 240K, the T of C2H2 maxThe temperature is 320K; the T of CO2 and C2H2 max The values ​​are all significantly higher than their boiling points. Unlike thermodynamically controlled adsorption systems, the adsorption behavior in this invention can be considered a kinetic factor; low temperatures hinder gas diffusion, while increasing temperature gradually promotes gas diffusion. It is noteworthy that although CO2 and C2H2 have exactly the same kinetic diameter and very similar molecular sizes, their T values ​​are significantly higher than their boiling points. max The values ​​differ by 80 K. Therefore, selectivity can be switched by temperature; FDC-3a adsorbs CO2 well in the 200–280 K range, while conversely selecting C2H2 in the 290–370 K range. The maximum adsorption ratios of CO2 / C2H2 and C2H2 / CO2 are 2.9 (220 K) and 3.6 (350 K), respectively. Figure 3 ).

[0064] 3. Results of selective separation of CO2 / C2H2 by switching temperature

[0065] Temperature-programmed adsorption-desorption (TPD) tests showed that the selective separation of CO2 / C2H2 could be switched by temperature changes. At 240 K, FDC-3a selectively adsorbed CO2 from a CO2 / C2H2 mixture, resulting in significant CO2 enrichment. Even in a mixed vapor mixture with a CO2:C2H2 ratio of 4.0:96.0, the CO2 adsorption ratio of FDC-3a still reached 95.4%, with a corresponding CO2 / C2H2 separation factor as high as 498.1. Figure 4 a) At 320 K, FDC-3a selectively adsorbs C2H2 from a CO2 / C2H2 mixture, resulting in significant C2H2 enrichment. Even in a CO2:C2H2 mixed vapor mixture of 93.8:6.2, the C2H2 adsorption ratio of FDC-3a still reaches 92.6%, with a corresponding C2H2 / CO2 separation factor as high as 180.7. Figure 4 b).

[0066] This invention controls the diffusion of gas molecules by synthesizing an ultramicroporous porous material through the arrangement of localized flexible structures at the pore outlets (i.e., the thiazide oxide folding structures are precisely arranged at the pore inlet and outlet, and the pore size is controlled by temperature). At low temperatures, due to the closed diffusion channels and the amplification of diffusion rate differences by this special pore structure, carbon dioxide diffuses much faster than acetylene, and only adsorbed carbon dioxide is recognized. As the temperature increases, the amplitude of the ligand folding motion gradually increases, causing the diffusion channels to gradually open, allowing both carbon dioxide and acetylene to diffuse. However, the interaction force between acetylene and the porous material is greater than that between carbon dioxide and the porous material, and adsorbed acetylene is recognized at high temperatures, thus exhibiting a temperature-responsive reversal recognition behavior.

Claims

1. A porous coordination polymer, characterized in that, The porous coordination polymer is formed by the self-assembly of organic ligands and metal ions as shown in Formula I through coordination bonds; Formula I In Formula I, R1 to R8 are each independently selected from -H, -CH3, -C2H5, and -OCH3; Y is selected from one of the following groups: , , or ; Furthermore, the metal ion is selected from one of zinc, cobalt, nickel, copper, sodium, potassium, or calcium.

2. The porous coordination polymer according to claim 1, characterized in that, The organic ligand is selected from one of the following substances: , or .

3. A porous coordination polymer according to claim 1 or 2, characterized in that, The dihedral angle of the two benzene rings of the organic ligand is 0~90 degrees. o ; The energy barrier of the organic ligand requires 0~30 kJ / mol. -1 ; The folding motion temperature of the organic ligand is 80~400 K.

4. A porous coordination polymer according to claim 1 or 2, characterized in that, The metal ions are selected from soluble metal salts.

5. The porous coordination polymer according to claim 4, characterized in that, The metal ions are selected from: nitrates, acetates, sulfates or chlorides of metal ions.

6. A porous coordination polymer according to claim 1 or 2, characterized in that, The porous coordination polymer has a pore size of 2.55 ~ 3.00 Å.

7. A porous coordination polymer according to claim 1 or 2, characterized in that, The porous coordination polymer adsorbs CO2 in the range of 200 ~ 280 K and selectively adsorbs C2H2 in the opposite range of 290 ~ 370 K.

8. A method for preparing the porous coordination polymer according to any one of claims 1 to 7, characterized in that, The preparation method is as follows: the organic ligand shown in Formula I is self-assembled with a salt containing metal ions through coordination bonds.

9. The application of the porous coordination polymer according to any one of claims 1 to 7 in the selective separation of CO2 and C2H2.

10. The application according to claim 9, characterized in that, The porous coordination polymers are separated at temperatures ranging from 200 to 370 K.

11. The application according to claim 9, characterized in that, The porous coordination polymer exhibits temperature-stimulated switching molecular recognition selectivity.

12. The application according to claim 9, characterized in that, The porous coordination polymer adsorbs CO2 at 200–280 K, and conversely selectively adsorbs C2H2 in the range of 290–370 K.

Images