Host-guest composite materials based on cage-like porous materials and TPA mononuclear iron complexes, their preparation methods and applications

Abstract

The present invention relates to the field of porous coordination polymer materials, specifically to a host-guest composite material based on a cage-shaped porous material and a TPA mononuclear iron complex, and its preparation method and application. Aiming at the problem that the TPA mononuclear iron complex is prone to dimerization reaction and deactivation during the catalytic reaction cycle, the present invention utilizes the confined space of a porous coordination polymer material with a cage-shaped pore structure, and in-situ synthesizes the TPA mononuclear iron complex in the pores of the porous material through the "two-step in-pore in-situ synthesis method" to construct a host-guest type composite material. The composite material prepared by the present invention is beneficial to combining the respective advantages of the host and guest frameworks, and at the same time utilizes the confinement effect of the host pores to change the physical and chemical properties of the guest molecules and improve the stability of the mononuclear iron complex.

Description

Technical Field

[0001] The present invention relates to the technical field of porous coordination polymer materials, and specifically to a host-guest composite material based on a cage-like porous material and a TPA mononuclear iron complex, and its preparation method and application, and a host-guest composite material based on [(TPA)Fe Ⅱ (CH3CN)2](SO3CF3)2@UiO-66 and its preparation method and application. Background Art

[0002] In recent years, among mononuclear transition metal complexes of aminobipyridine ligands, iron is abundant in the earth's crust (the fourth in the earth's crust content, about 4.7 wt%), and its complexes have flexible variable valence states (commonly +2 and +3), and are easily coordinated with ligand elements such as oxygen and nitrogen to form stable complexes. Functional mononuclear complexes of the inexpensive metal iron have shown strong functionality / reactivity in the fields of photoluminescence energy transfer, redox catalysis, and bioinorganic chemistry. So far, more than a dozen iron aminobipyridine complexes have been synthesized and characterized, which can be classified into three categories: macrocyclic tetracoordinate N4 structure, tripod topology aminopyridine tetracoordinate N4 structure, and aminopyridine pentacoordinate N5 structure, with TMC, TPA, and N4Py as their representative structures (as Figure 1 shown), and the rest are mostly root-derived complexes of these three types of ligands. Among them, transition metal complexes containing polypyridyl ligands have received extensive attention and will continue to do so due to their potential applications in the fields of photoinitiated energy transfer, redox catalysis, and bioinorganic chemistry.

[0003] Tris(2-pyridylmethyl)amine (TPA for short) is a nitrogen-containing pyridyl-based tetradentate ligand. Because TPA has many potential coordination modes, the coordination geometries of its metal complexes are usually of two types: one is that the ligand is part of the coordination configuration, and the coordination configuration has a C3 symmetry axis, such as the trigonal bipyramidal metal ion complex of TPA; the other is that the ligand spans the meridional plane of the coordination sphere, such as the octahedral metal ion complex of TPA. Since this ligand was first reported by Anderegg and Wenk in 1967, it has been used to study the coordination chemistry of various transition metal ions. Mononuclear transition metal complexes based on the TPA ligand have many important applications in the catalytic field. For example, it has been found that in the presence of the ligand TPA, iron complexes can undergo catalytic reactions such as peroxide oxidation, oxygen binding and activation, water oxidation, hydrogen production, nitro transfer, etc. In addition, mononuclear iron complexes based on such ligands also have photochemical activity and gas adsorption reaction activity, etc., and have great application potential in the future field of functional molecules. However, mononuclear iron complexes based on the TPA ligand are extremely unstable and easily undergo binuclear coupling to form binuclear complexes, resulting in loss of reactivity. Under the current homogeneous solution conditions, there has been no progress in the study of their stability.

[0004] Different from the open space of homogeneous solutions, the confined system of solid porous materials can regulate the chemical and physical properties of active substances through interfacial confinement, increase the local concentration of reactants, thereby improving the chemical reaction rate, enhancing the selectivity of reactants and the stability of catalysts. When functional molecules are in the confined space, due to physical space constraints and chemical interfacial interactions, the spatial configuration of functional molecules, as well as the electronic structures of mononuclear metal centers or ligands, will change, thus leading to obvious changes in the physicochemical properties such as the photochemical properties, catalytic activity and reactivity of substances. Currently, there are many kinds of materials commonly used to construct confined spaces, such as coordination cages, hydrogen-bonded capsules, protein cages, vesicles and micelles, zeolites, covalent organic frameworks (COFs) and porous coordination polymers (PCPs). Among them, PCP materials are novel porous network materials assembled by metal ions (or metal ion clusters) and organic ligands through coordination. These materials have been widely concerned due to their large specific surface area, high porosity, diverse structures, etc. Utilizing the highly adjustable pore size and pore chemical environment of PCP materials, combined with the functional matching design that is conducive to improving / enhancing the functionality of mononuclear complexes, it is of great research significance to construct host-guest composite materials with good synergistic effects. For example, in 2008, researchers placed a relatively large metal porphyrin catalyst (In-HImDC) in rho-ZMOF. Experiments found that under the same conditions, using tert-butyl hydroperoxide (TBHP) as the oxidant, chlorobenzene as the internal standard, the loaded MOF as the catalyst, and oxidizing at 65 °C, the total yield (from cyclohexane to cyclohexanol / cyclohexanone) and the corresponding turnover number (TON) were significantly improved compared with other reaction systems; in the research results in 2021, complexes of Re and Ru were loaded into the MIL-101 structure, and the synergistic effect of the two complexes achieved highly reactive carbon dioxide reduction. In addition to changing the catalytic effect, the host-guest material Ru(bpy)2(dpbpy)@IRMOF-10 synthesized by Yan et al. has both blue and red light emissions.

[0005] Currently, methods for changing the photochemical properties of mononuclear iron metal complexes containing polypyridyl ligands and improving their stability as catalysts include those controlled by reaction conditions, such as changing the pH of the reaction solution, increasing external conditions such as light and electricity; in addition to controlling by changing reaction conditions, there is also changing the ligand structure. However, although the effects of these traditional solutions have been improved to some extent, they are not satisfactory. Summary of the Invention

[0006] Aiming at the problem that the current TPA mononuclear iron complex is prone to dimerization reaction during the catalytic reaction cycle, resulting in inactivation, the present invention provides a host-guest composite material based on a cage-like porous material and a TPA mononuclear iron complex, its preparation method and application. By utilizing the confined space of the pores of the porous coordination polymer material, a mononuclear iron complex is in-situ synthesized in the pores of the porous material through "two-step in-pore in-situ synthesis" to construct a host-guest type composite material, and the stability of the mononuclear iron complex is improved by the confinement effect of the host pores. At the same time, the composite material prepared by the present invention is beneficial to combining the respective advantages of the host and guest frameworks, and constructs a new composite material that can be used for various purposes such as catalysis, gas adsorption, and photochemical reactions.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A host-guest composite material based on a cage-like porous material and a TPA mononuclear iron complex, the molecular formula of the host-guest composite material is: [(TPA)Fe Ⅱ (CH3CN)2](SO3CF3)2@UiO-66.

[0009] The present invention also protects a preparation method of a host-guest composite material based on a cage-like porous material and a TPA mononuclear iron complex. The host-guest composite material is prepared by a two-step in-pore in-situ synthesis method, and the two-step in-pore in-situ synthesis method includes the following steps:

[0010] (1) Preparation of TPA@UiO-66: Add a mononuclear iron complex TPA ligand to the reaction solution of UiO-66, then carry out the growth of the cage-like porous material, and then obtain TPA@UiO-66 after centrifugation and washing;

[0011] (2) Preparation of the host-guest composite material: Place the TPA@UiO-66 material in step (1) into an aqueous acetonitrile solution of iron(II) trifluoromethanesulfonate, stir at room temperature for 2-6 h, and then obtain [(TPA)Fe Ⅱ (CH3CN)2](SO3CF3)2@UiO-66 after filtration and washing.

[0012] Preferably, the UiO-66 solution in step (1) is prepared according to the following steps:

[0013] Dissolve terephthalic acid and zirconium oxychloride octahydrate in a solvent and mix evenly. The solvent is a mixed solution of glacial acetic acid and N,N ， -dimethylformamide;

[0014] Among them, the molar ratio of the TPA ligand to zirconium in zirconium oxychloride octahydrate is 1:1-2.

[0015] Preferably, the growth method of the cage-like porous material in step (1) is: heating and stirring until all the solid powder is dissolved, and then standing at 70 - 90 °C for 6 - 12 h.

[0016] Preferably, in step (2), the molar ratio of the TPA@UiO-66 material to iron(II) trifluoromethanesulfonate is 1:1 - 1.5.

[0017] Preferably, in the acetonitrile aqueous solution of step (2), the volume ratio of H2O to CH3CN is 1:1 - 3.

[0018] The present invention also protects the application of the host-guest composite material based on the cage-like porous material and the TPA mononuclear iron complex in the preparation of carbon monoxide gas adsorption and separation materials, photoinduced energy transfer materials, redox catalytic materials, and bioinorganic chemistry materials. The host-guest composite material of the present invention aims to solve the problem that the mononuclear iron complex is prone to dimerization reaction during the catalytic reaction cycle, resulting in inactivation. Therefore, its application is consistent with that of the functional mononuclear complex.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. This application uses the porous coordination polymer (PCP) material with various applications and rich structures as the main structure, and the multifunctional TPA mononuclear metal iron complex as the guest. According to the properties of the host and the guest, the [(TPA)Fe Ⅱ (CH3CN)2](SO3CF3)2@UiO-66 host-guest system composite material was successfully prepared by the "two-step in-pore in-situ synthesis method", and then the host-guest assembly law of such mononuclear iron complexes in the PCP nanopores was preliminarily explored. The host-guest system can combine and influence the functions of the host, the functions of the guest molecules, and the confinement effect brought by the pores, thereby avoiding the problem that the current aminobipyridine mononuclear iron complex is prone to dimerization reaction during the catalytic reaction cycle, resulting in inactivation, improving the application ability, and also studying the influence of the confinement effect on the physical and chemical properties of the host and guest molecules.

[0021] 2. The present invention prepared the FeTPA@UiO-66 system by the "two-step in-pore in-situ synthesis method". The "two-step in-pore in-situ synthesis" means that: first, the guest molecule ligand, namely TPA, is pre-encapsulated into the cage cavity of UiO-66 by the in-situ synthesis method, and then divalent iron ions are diffused into the cage cavity of UiO-66 by soaking. The in-situ synthesis of guest molecules is carried out in the pores of the metal-organic porous material, and iron(II) trifluoromethanesulfonate and acetonitrile are respectively bonded to TPA to form coordination bonds, that is, the "two-step in-pore in-situ synthesis method", to obtain the host-guest assembled [(TPA)Fe Ⅱ(CH3CN)2](SO3CF3)2@UiO-66 material. Description of the Drawings

[0022] Figure 1 Structural formulas of the macrocyclic tetracoordinated N4 structure (TMC), tripod topological aminopyridine tetracoordinated N4 structure (TPA), and aminopyridine pentacoordinated N5 structure (N4Py) in the background art of the present invention;

[0023] Figure 2 Deactivation reaction path diagram of the high-valent iron complex in the background art of the present invention;

[0024] Figure 3 Synthesis schematic diagram of the FeTPA@UiO-66 host-guest system "two-step in-situ synthesis method" in Examples 1-3 of the present invention;

[0025] Figure 4 In Example 2 of the present invention, (a) XRD spectra of the TPA@UiO-66 sample and the TPA sample; (b) Comparative diagram of the TGA curves of the TPA, UiO-66, and TPA@UiO-66 samples;

[0026] Figure 5 In Example 2 of the present invention, (a) 1H NMR spectrum of the TPA sample; (b) 1H NMR spectrum of the TPA@UiO-66 sample after digestion;

[0027] Figure 6 In Example 2 of the present invention, (a) Color comparison diagram of the TPA@UiO-66 sample and the FeTPA@UiO-66 host-guest system sample; (b) XRD spectra of the TPA@UiO-66 sample and the UiO-66 sample;

[0028] (c) Comparative diagram of the TGA curves of the TPA@UiO-66 sample, the TPA@UiO-66 sample, and the FeTPA sample;

[0029] Figure 7 In Example 2 of the present invention, the upper figure is the FT-IR spectra of the TPA@UiO-66 sample, the UiO-66 sample, and the FeTPA sample, and the lower figure is an enlarged view of the upper figure;

[0030] Figure 8 In Example 2 of the present invention, UV-visible light spectrum of the FeTPA@UiO-66 release experiment. Detailed Embodiments

[0031] The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings of the present invention. However, it should be understood that the protection scope of the present invention is not limited by the specific embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the protection scope of the present invention. The raw materials used in the present invention that are not specified by the manufacturer can all be obtained as conventional products through commercial purchase.

[0032] Example 1

[0033] A preparation method of a host-guest composite material based on a cage-like porous material and a TPA mononuclear iron complex includes the following steps:

[0034] (1) Preparation of TPA@UiO-66: Weigh 1.00 g (6 mmol) of terephthalic acid (BDC) and 0.420 g (1.3 mmol) of zirconium oxychloride octahydrate (ZrOCl2·8H2O) and dissolve them in a mixed solution of 40 mL of glacial acetic acid and 60 mL of N,N ， -dimethylformamide (DMF) to obtain solution a;

[0035] Weigh 0.377 g (1.3 mmol) of TPA and dissolve it in 40 mL of DMF to obtain solution b;

[0036] Add solution b to solution a, heat to 90 °C, stir for 10 min until all the solid powder is dissolved, stop stirring, and then let it stand at 90 °C for 6 h. After the reaction is completed, centrifuge to remove the mother liquor, wash with ultrapure water 3 times to remove the surface raw materials, and finally obtain a white powder, which is TPA@UiO-66;

[0037] (2) [(TPA)Fe Ⅱ (CH3CN)2](SO3CF3)2@UiO-66: Weigh 0.10 g of TPA@UiO-66 and 0.015 g (0.04 mmol) of iron(II) trifluoromethanesulfonate (FeOTf) in a glass vial, add 2 mL of an ultrapure aqueous solution of acetonitrile, and the volume ratio of acetonitrile to ultrapure water is 3:1. Stir at room temperature for 2 h, filter to remove the mother liquor, and wash with ultrapure water to remove the unreacted FeOTf to obtain a light yellow powder, which is [(TPA)Fe Ⅱ (CH3CN)2](SO3CF3)2@UiO-66 (hereinafter simply referred to as FeTPA@UiO-66) synthesized by the "two-step in-pore in-situ synthesis method".

[0038] Example 2

[0039] A preparation method of a host-guest composite material based on a cage-like porous material and a TPA mononuclear iron complex includes the following steps:

[0040] (1) Preparation of TPA@UiO-66: Weigh 1.00 g (6 mmol) of terephthalic acid (BDC) and 0.420 g (1.3 mmol) of zirconium oxychloride octahydrate (ZrOCl₂·8H₂O) and dissolve them in a mixed solution of 40 mL of glacial acetic acid and 60 mL of N,N ， -dimethylformamide (DMF) to obtain solution a;

[0041] Weigh 0.1885 g (0.65 mmol) of TPA and dissolve it in 40 mL of DMF to obtain solution b;

[0042] Add solution b to solution a, heat the mixture to 70 °C, stir for 30 min until all the solid powder is dissolved, stop stirring, let it stand at 70 °C for 12 h. After the reaction is completed, centrifuge to remove the mother liquor, wash it with ultrapure water three times to remove the surface raw materials, and finally obtain a white powder, which is TPA@UiO-66;

[0043] (2) [(TPA)Fe Ⅱ (CH₃CN)₂](SO₃CF₃)₂@UiO-66: Weigh 0.10 g of TPA@UiO-66 and 0.0075 g (0.02 mmol) of iron(II) trifluoromethanesulfonate (FeOTf) in a glass vial, add 2 mL of ultrapure water, stir at room temperature for 2 h, filter to remove the mother liquor, and wash with ultrapure water to remove the unreacted FeOTf to obtain a pale yellow powder, which is [(TPA)Fe Ⅱ (CH₃CN)₂](SO₃CF₃)₂@UiO-66 (hereinafter simply referred to as FeTPA@UiO-66) synthesized by the "two-step in-pore in-situ synthesis method".

[0044] Example 3

[0045] A preparation method of a host-guest composite material based on a cage-like porous material and a TPA mononuclear iron complex, comprising the following steps:

[0046] (1) Preparation of TPA@UiO-66: Weigh 1.00 g (6 mmol) of terephthalic acid (BDC) and 0.420 g (1.3 mmol) of zirconium oxychloride octahydrate (ZrOCl₂·8H₂O) and dissolve them in a mixed solution of 40 mL of glacial acetic acid and 60 mL of N,N ， -dimethylformamide (DMF) to obtain solution a;

[0047] Weigh 0.14 g (1 mmol) of TPA and dissolve it in 40 mL of DMF to obtain solution b;

[0048] Add solution b to solution a and heat to 80 °C. Stir for 20 min until all the solid powder is dissolved. Stop stirring and let it stand at 80 °C for 10 h. After the reaction is completed, centrifuge to remove the mother liquor and wash it 3 times with ultrapure water to remove the surface raw materials. Finally, a white powder, namely TPA@UiO-66, is obtained.

[0049] (2)[(TPA)Fe Ⅱ (CH3CN)2](SO3CF3)2@UiO-66: Weigh 0.10 g of TPA@UiO-66 and 0.0075 g (0.02 mmol) of iron(II) trifluoromethanesulfonate (FeOTf) into a glass vial. Add 2 mL of ultrapure water and stir at room temperature for 6 h. Filter off the mother liquor by suction and wash away the unreacted FeOTf with ultrapure water to obtain a pale yellow powder, namely [(TPA)Fe Ⅱ (CH3CN)2](SO3CF3)2@UiO-66 (hereinafter simply referred to as FeTPA@UiO-66).

[0050] In Examples 1-3 of the present invention, host-guest composite materials based on cage-like porous materials and TPA mononuclear iron complexes were all prepared. Next, the preparation principle, as well as the TPA@UiO-66 sample, FeTPA@UiO-66, and FeTPA sample were studied. The FeTPA sample is a commercially available sample with the molecular formula: (TPA)Fe Ⅱ (CH3CN)2](SO3CF3) 2， Named: iron(III) trifluoromethanesulfonate. The specific research methods are as follows:

[0051] (I) Explanation of the preparation principle:

[0052] In the present invention, the FeTPA@UiO-66 system is synthesized by the "two-step in-situ synthesis method in pores". The "two-step in-situ synthesis in pores" means that: First, the guest molecule ligand, namely TPA, is pre-encapsulated into the cage cavity of UiO-66 by the in-situ synthesis method. Then, divalent iron ions are diffused into the cage cavity of UiO-66 by soaking, and in-situ coordination synthesis of guest molecules is carried out in the pore channels of the metal-organic porous material, that is, the "two-step in-situ synthesis method in pores", to obtain the host-guest assembly FeTPA@UiO-66. The specific assembly schematic diagram is as Figure 3 shown.

[0053] Using the "two-step in-situ synthesis in pores" FeTPA@UiO-66 host-guest system can completely avoid the dimerization reaction of iron complexes and solve its instability problem at the root. This is because the cage-like pore channels of UiO-66 spontaneously isolate the iron complexes in individual small rooms, avoiding the formation of binuclear iron complexes.

[0054] (2) Research on TPA@UiO-66:

[0055] Figure 4 They are the XRD pattern and thermogravimetric curve of the ligand pre-assembled sample TPA@UiO-66. In the original synthesis solution, the molar ratio of TPA to Zr is 1:2. The XRD pattern of the synthesized sample is basically consistent with the theoretical calculation results of the TPA sample without encapsulated ligand. Figure 4 The XRD pattern in a indicates that the ligand of the guest molecule does not affect the structure of the host framework. As Figure 4 The thermogravimetric analysis results in b show that compared with the unencapsulated TPA sample, the encapsulated ligand sample TPA@UiO-66 has a small additional weight loss in the range of 250-350 °C, and the weight loss temperature is slightly higher than that of pure TPA. Considering that the ligand in the pore is more stable than the free ligand, this part of the weight loss belongs to the TPA ligand in the pore.

[0056] In order to further characterize the existence state of the TPA ligand in the UiO-66 pore, the sample of TPA@UiO-66 was characterized by H-NMR in the study. In the experiment, UiO-66 was alkali-digested with 500 mmol / L sodium hydroxide solution to release the ligand molecules inside the pore for nuclear magnetic characterization. The precipitate after digestion was detected by XRD. As no XRD peak was found, it was considered that the UiO-66 structure was completely digested. After centrifugation, the supernatant was taken and the pH was adjusted to weakly acidic with hydrochloric acid, and then rotary evaporation was used to remove the solvent water. Finally, it was dissolved in deuterated dimethyl sulfoxide (DMSO-d6), and the supernatant was taken for nuclear magnetic testing.

[0057] The nuclear magnetic comparison results of the pure TPA ligand and the digested TPA@UiO-66 are as Figure 5 shown. The experiment found that the stronger the acidity, the more the TPA nuclear magnetic peak will shift towards the strong field direction. Therefore, in Figure 5 b, the peak at 8.3 ppm was attributed to the peak at 8.5 ppm under neutral conditions, that is, Figure 5 in a. This peak is the hydrogen atom adjacent to N in the pyridine ring of the TPA ligand. The peak at 8.09 ppm is the hydrogen on the benzene ring of the terephthalic acid ligand of UiO-66. Through integral calculation, it is obtained that the molar ratio of TPA to terephthalic acid in the in-situ synthesized TPA@UiO-66 is about 1:12, that is, TPA can occupy about 56% of the large cages in UiO-66.

[0058] (3) Research on FeTPA@UiO-66:

[0059] After obtaining the TPA@UiO-66 sample, iron ions were diffused into the UiO-66 cages by stirring and soaking, so that the TPA ligand and iron ions were coordinated in situ in the pores to form FeTPA complexes. To prevent as little TPA ligand as possible from escaping from the pores during the stirring and soaking process, ultrapure water, a poorly soluble solvent of the TPA ligand, was used as the soaking solvent. After soaking for 2 h, the product was obtained by filtration.

[0060] Figure 6 Figure a shows the color contrast before and after the "two-step in-situ synthesis in pores". The sample TPA@UiO-66 before the diffusion of divalent iron ions was bright white, while the color of the sample after the diffusion was changed from white to light red, indicating the formation of mononuclear iron complexes. Figure 6 As can be seen from the XRD pattern in Figure b, the framework structure of UiO-66 did not change before and after soaking, indicating that divalent iron ions did not affect the structure of the host framework material. Figure 6 As can be seen from the TGA spectrum in Figure c, compared with the weight loss of the TPA@UiO-66 sample before and after soaking in the iron ion solution, the second weight loss temperature increased significantly, from 200 - 300 °C to 300 - 400 °C, that is, from the weight loss temperature of TPA to the weight loss temperature range of FeTPA, successfully verifying the in-situ synthesis of mononuclear iron complexes in the pores.

[0061] To further characterize the existence state of iron complexes in the pores and exclude the possibility that iron elements exist in the pores in the form of ferrous salts (ferrous trifluoromethanesulfonate), Fourier transform infrared spectroscopy was used for testing. The test results are shown in Figure 7 As shown in the figure, compared with the TPA@UiO-66 sample, an obvious infrared absorption peak of FeTPA at 1230 cm -1 appeared in the FeTPA@UiO-66 sample. At the same time, an infrared absorption peak of FeTPA at 1034 cm -1 and an infrared absorption peak of UiO-66 at 1018 cm -1 appeared in the FeTPA@UiO-66 sample.

[0062] To verify whether the stability of the mononuclear iron complex was improved in the pores of the porous material, a release test was also carried out. The complex in the pores was released in situ with acetonitrile, a good solvent for the mononuclear iron complex, and ultraviolet-visible spectroscopy was used for testing. As Figure 8 can be seen, with the extension of time (3 min - 30 min), the guest molecules in the pores slowly escaped and the concentration gradually increased. The corresponding ultraviolet absorption spectrum was the ultraviolet-visible absorption spectrum of the mononuclear iron complex, indicating that the guest molecules in the pores existed completely in the form of mononuclear iron, and no ultraviolet absorption peak of the binuclear iron complex was found, fully verifying that the "two-step in-situ synthesis" indeed improved the stability of the mononuclear iron complex.

[0063] Finally, ICP test was carried out on the obtained sample. The mass fraction of iron element in the sample is 0.98%, and the molar mass ratio to the measured zirconium element is 1:12. Compared with the theoretical calculated value, it occupies about 50% of the large cages of UiO-66. This result is close to the pore occupancy value of 56% of the complex ligand TPA measured by NMR, which also provides favorable support for the successful host-guest assembly of this system by using the "two-step in-pore in-situ synthesis".

[0064] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A host-guest composite material based on a cage-like porous material and a TPA mononuclear iron complex, characterized in that, The host-guest composite material is prepared by a two-step in-situ synthesis method in pores, and the two-step in-situ synthesis method in pores includes the following steps: (1) Preparation of TPA@UiO-66: Add the mononuclear iron complex TPA ligand to the reaction solution of UiO-66, then carry out the growth of the cage-like porous material, and after centrifugation and washing, obtain TPA@UiO-66; (2)Preparation of host-guest composite material: The TPA@UiO-66 material obtained in step (1) was placed into an aqueous acetonitrile solution of iron(II) trifluoromethanesulfonate, stirred at room temperature for 2 - 6 h, and then filtered and washed to obtain [(TPA)Fe Ⅱ (CH3CN)2](SO3CF3)2@UiO-66.

2. The host-guest composite material based on the cage-like porous material and the TPA mononuclear iron complex according to claim 1, characterized in that, The UiO-66 solution in step (1) is prepared according to the following steps: Dissolve terephthalic acid and zirconium oxychloride octahydrate in a solvent and mix evenly. The solvent is a mixed solution of glacial acetic acid and N,N ， -dimethylformamide; Among them, the molar ratio of the TPA ligand to zirconium in zirconium oxychloride octahydrate is 1:1-2.

3. The host-guest composite material based on the cage-like porous material and the TPA mononuclear iron complex according to claim 1, wherein The growth method of the cage-like porous material in step (1) is: heat and stir until all the solid powder is dissolved, and then stand at 70-90 °C for 6-12 h.

4. The host-guest composite material based on the cage-like porous material and the TPA mononuclear iron complex according to claim 1, characterized in that, In step (2), the molar ratio of the TPA@UiO-66 material to iron(II) trifluoromethanesulfonate is 1:1-1.

5.

5. The host-guest composite material based on the cage-like porous material and the TPA mononuclear iron complex according to claim 1, wherein In the acetonitrile aqueous solution of step (2), the volume ratio of H2O to CH3CN is 1:1-3.

6. Application of the host-guest composite material based on the cage-like porous material and the TPA mononuclear iron complex described in claim 1 in the preparation of carbon monoxide gas adsorption and separation materials, photoinduced energy transfer materials, redox catalytic materials, and bioinorganic chemistry materials.

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