A hydrogen-bonded aromatic amide molecular cage compound, its preparation method and applications

Abstract

The present invention discloses a hydrogen-bonded aromatic amide molecular cage compound, a preparation method thereof and an application thereof, belonging to the technical field of porous organic functional materials. In the present invention, an imine intermediate is synthesized by a dynamic covalent chemical imine condensation reaction of a hydrogen-bonded oligomeric aromatic amide diamine monomer and a trialdehyde monomer in dichloromethane, and then in-situ one-pot reduction is carried out using NaBH3CN to finally obtain an aromatic amide cage molecule. The preparation method is simple, and the reaction monomers are cheap and easily available. At the same time, the hydrogen-bonded aromatic amide molecular cage compound prepared in the present invention has high thermal stability and high chemical stability, and can efficiently adsorb iodine in solution state and gas phase (including I2, I3 ‑ and CH3I), and can be applied to the design and development of high-performance radioactive iodine capture materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of porous organic functional materials, and particularly relates to a hydrogen-bonded arylamide molecular cage compound, a preparation method thereof, and an application thereof. Background Art

[0002] Radioactive iodine (such as 129 I and 131 I) as a fission product of 239 Pu and 235 U in nuclear power plants is considered to be one of the most harmful radionuclides. Its easy sublimation, high solubility, diverse existence forms (such as inorganic iodine: I2, I 2n+1 - , IO3 - ; organic iodine: CH3I / CH3CH2I, etc.) and redox reaction activity, etc., make it extremely easy to migrate and diffuse in the ecosystem, causing many challenging problems for the efficient capture of radioactive iodine.

[0003] At present, the adsorption materials mainly used in nuclear industry technology include silver-impregnated molecular sieves, activated carbon, Al2O3, SiO2, etc., for iodine adsorption in radioactive waste gas and liquid. Although the above materials have stable structures, low costs, and can be prepared on a large scale, these materials generally have problems such as easy aging, low iodine adsorption capacity (the adsorption capacity is usually less than 1 g / g), relatively slow adsorption kinetics, and difficulties in material activation regeneration and recycling, which greatly limit their practical applications.

[0004] In recent years, porous materials with extended network framework structures, such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), porous organic polymers (POPs), etc., have become ideal research platforms for developing high-performance iodine adsorption functional materials due to their diverse structures and easy customization design, low framework density, high specific surface area, rich pore structures, and adjustable pore sizes. However, the strong acidic conditions and high water content during the nuclear fission product treatment process are likely to cause poor structural stability of MOF materials, resulting in reduced or even lost performance. In addition, COF and POP materials are formed by covalent bonds. Although their structural stability is relatively good, there are widespread problems such as poor crystallinity, complex defect structures, and unclear chemical structures during the material synthesis process, which are not conducive to the study of the adsorption mechanism during the iodine adsorption process and the revelation of iodine bonding forces, and it is difficult to rationally guide the design synthesis and performance optimization of materials. In addition, these polymer materials usually have poor solubility or even insoluble, which greatly hinders the activation regeneration cycle and dissolution processing use of the materials.

[0005] Macrocyclic compounds and organic cage molecules are a type of discrete porous molecular materials (PMMs). They usually have inherently customizable cavities, stable chemical structures, are easy to functionalize, and can be dissolved and processed. Compared with framework materials, their clear chemical structures and precisely functionalizable structural features contribute to the study of iodine adsorption mechanisms. In view of this, there is an urgent need to develop new porous functional materials with high adsorption capacity, fast adsorption kinetics, simple synthesis, high cost-effectiveness, good stability, and easy activation and recycling for efficient iodine capture. Summary of the Invention

[0006] Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a hydrogen-bonded arylamide molecular cage compound, its preparation method and application, to solve the problems of easy aging of radioactive iodine adsorption materials, low iodine adsorption capacity, slow adsorption kinetics, poor solubility, and poor structural stability in the prior art.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: Provide a hydrogen-bonded arylamide molecular cage compound, the structural formula of which is shown in formula (Ⅰ):

[0008]

[0009] In formula (Ⅰ), R is X is CH or N.

[0010] The beneficial effects of the present invention are as follows: The hydrogen-bonded arylamide molecular cage compound provided by the present invention does not contain metals, is an organic molecule with a clear structure, and has an inherent three-dimensional cavity and a backbone structure stabilized by intramolecular hydrogen bonds. During the adsorption of iodine, in the cavity of the cage molecule, by enhancing cooperative non-covalent interactions, or by introducing nitrogen atoms to create active adsorption sites, the lone pair electrons on the nitrogen atoms can be transferred to the antibonding orbital (σ*) of I2, thereby forming a strong charge transfer complex. At the same time, the pyridine-N atom and the six intramolecular hydrogen bond pre-organized carbonyl oxygen atoms act as binding sites in its cavity to play a synergistic role, which can effectively enhance the binding affinity of the adsorption material for iodine; by replacing the side chains of aromatic oligomeric amides and incorporating additional oxygen atoms into the cage molecule, the iodine adsorption ability can also be enhanced.

[0011] On the basis of the above technical solution, the present invention can also be improved as follows:

[0012] Further, X is CH, and R is Or, X is N, and R is

[0013] The present invention also provides a preparation method of the above hydrogen-bonded arylamide molecular cage compound, including the following steps:

[0014] S1: Take the hydrogen-bonded oligomeric aromatic amide diamine monomer 1 and the trialdehyde monomer 2, dissolve them in an organic solvent to obtain a reaction solution; the structural formulas of the hydrogen-bonded oligomeric aromatic amide diamine monomer 1 and the trialdehyde monomer 2 are as follows, where R is X is CH or N;

[0015]

[0016] S2: Stir and react the reaction solution at 35 - 45 °C for 100 - 140 h to obtain a reaction solution containing the imine intermediate 1; the structural formula of the imine intermediate 1 is as follows:

[0017]

[0018] S3: Add a reducing agent solution to the reaction solution containing the imine intermediate 1, stir and react for 16 - 20 h, and remove the solvent by vacuum distillation to obtain a crude product;

[0019] S4: Separate and purify the crude product to obtain the product.

[0020] Based on the above technical solutions, the present invention can be further improved as follows:

[0021] Further, the molar ratio of the hydrogen-bonded oligomeric aromatic amide diamine monomer 1 to the trialdehyde monomer 2 is 3:2.

[0022] Further, the organic solvent is dichloromethane.

[0023] Further, the reducing agent solution is prepared by dissolving NaBH3CN in methanol.

[0024] Further, the specific steps of separation and purification in S4 are: add anhydrous methanol to the crude product for solid-liquid extraction, and filter under reduced pressure to obtain a filter residue; thermally dissolve the filter residue with a mixed solution of dichloromethane and methanol, and then add anhydrous methanol for reprecipitation to obtain a crude product; recrystallize the crude product with a mixed solution of dichloromethane and methanol, filter under reduced pressure to obtain a filter residue, and wash the filter residue with ether.

[0025] Further, the volume ratio of dichloromethane to methanol in the mixed solution of dichloromethane and methanol used for dissolving the filter residue is 20:1, and the volume ratio of dichloromethane to methanol in the mixed solution of dichloromethane and methanol used for recrystallization is 1:1.

[0026] The present invention also provides an application of the above hydrogen-bonded aromatic amide molecular cage compound in capturing radioactive element iodine.

[0027] Based on the above technical solutions, the present invention can be further improved as follows:

[0028] Further, the existence form of the radioactive element iodine is iodine vapor or organic iodine compound.

[0029] The present invention has the following beneficial effects:

[0030] 1. The present invention synthesizes an imine intermediate through the dynamic covalent chemical imine condensation reaction of a hydrogen-bonded oligomeric aromatic amide diamine monomer and a trialdehyde monomer in dichloromethane, and then uses NaBH3CN for reduction in an in-situ one-pot method, and finally obtains an aromatic amide cage molecule. The preparation method is simple, and the reaction monomers are cheap and easily available.

[0031] 2. The BET specific surface area of the hydrogen-bonded aromatic amide molecular cage compound prepared by the present invention reaches 645.8 m 2 / g, and it has high thermal stability and high chemical stability, and can be applied to harsh environments. Most current iodine adsorption materials have a high adsorption capacity under low-temperature (T≤80 °C) and high-concentration iodine vapor (>10000 ppmv) conditions, but it is difficult to be applied under industrial application conditions (T≥150 °C, I2 concentration: ~150 ppmv). The material prepared by the present invention has excellent iodine vapor capture performance under the above environmental conditions.

[0032] 3. R1, PyR1, and PyR2 prepared by the present invention can efficiently adsorb various forms of iodine (including I2, I3 - and CH3I) in the solution state and gas phase. PyR1 introduces a pyridine-N cap for internal engineering. Due to the synergistic effect of the pyridine-N atom and six intramolecular hydrogen-bond preorganized carbonyl oxygen atoms as binding sites in its cavity, PyR1 shows high affinity, resulting in an iodine adsorption capacity of 5.37 g / g in aqueous solution (equivalent to 56 I2 per cage), 2.17 g / g in cyclohexane, and 9.68 g / g in KI / I2 solution, even in the presence of excess competing anions. PyR2 enhances the iodine adsorption ability by replacing the side chain of the aromatic oligomeric amide and incorporating additional oxygen atoms into PyR1. Its adsorption capacity for I3 - in aqueous solution remains at a high level of about 9.58 g / g and shows an enhanced adsorption capacity of 2.90 g / g in cyclohexane. Description of the Drawings

[0033] Figure 1 It is a thermogravimetric analysis diagram of hydrogen-bonded aromatic amide molecular cage compounds R1, PyR1, and PyR2, where Figure (a) is R1, Figure (b) is PyR1, and Figure (c) is PyR2;

[0034] Figure 2 It is an iodine vapor adsorption curve diagram of hydrogen-bonded aromatic amide molecular cage compounds R1, PyR1, and PyR2 changing with time, where the inset is a color change diagram of R1 before and after adsorbing iodine vapor;

[0035] Figure 3Quasi-first-order kinetic fitting plots of the iodine vapor adsorption curves of hydrogen-bonded aromatic amide molecular cage compounds R1, PyR1, and PyR2 over time;

[0036] Figure 4 Graph showing the variation of the adsorption capacity of hydrogen-bonded aromatic amide molecular cage compounds R1, PyR1, and PyR2 for methyl iodide over time, where the inset is a graph of the color and property changes of cage R1 before and after adsorbing methyl iodide. Detailed implementation mode

[0037] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. For those not specified in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0038] Example 1:

[0039] A hydrogen-bonded aromatic amide molecular cage compound R1, whose structural formula is shown in formula (II):

[0040]

[0041] In formula (II), R is

[0042] The preparation method of the above-mentioned hydrogen-bonded aromatic amide molecular cage compound includes the following steps:

[0043] S1: Weigh hydrogen-bonded oligomeric aromatic amide diamine monomer 1 (0.048 mmol, 3 eq.) and trialdehyde monomer 2 (0.032 mmol, 2 eq.) in a 25 mL Schlenk reaction tube, add 10 mL of dry dichloromethane to dissolve, and obtain a reaction solution;

[0044] The structural formulas of hydrogen-bonded oligomeric aromatic amide diamine monomer 1 and trialdehyde monomer 2 are shown as follows:

[0045]

[0046] Among them, R is

[0047] S2: Stir and react the reaction solution at 40 °C for 5 days. During this period, monitor the reaction process using TLC thin-layer chromatography. When the raw materials are completely converted, an insoluble yellow precipitate forms in the reaction solution, and a reaction solution containing imine intermediate 1 is obtained;

[0048] The structural formula of imine intermediate 1 is shown as follows:

[0049]

[0050] wherein, R is

[0051] S3: Weigh NaBH3CN (24.5 mg, 0.39 mmol) and dissolve it in 2 mL of methanol. Then add it to the reaction solution containing imine intermediate 1, and stir at room temperature for the reduction reaction. During the reaction, the yellow insoluble precipitate gradually dissolves, and the solution changes from yellow to light green. After reacting for 18 h, monitor the reaction process by TLC. When imine intermediate 1 completely disappears, stop the reaction, and remove the solvent by vacuum distillation to obtain the crude product.

[0052] S4: Add 30 mL of anhydrous methanol to the obtained crude product, perform solid-liquid extraction and washing twice, then filter under reduced pressure. The filter residue is dissolved by heating with 10 mL of CH2Cl2 / MeOH (20 / 1, v / v) mixed solution, and then reprecipitated with 30 mL of anhydrous methanol to obtain the crude product. The crude product is recrystallized with CH2Cl2 / MeOH (1 / 1, v / v), filtered under reduced pressure, and the filter residue is rinsed with 30 mL of ether to obtain the hydrogen-bonded aromatic amide molecular cage compound R1.

[0053] Example 2:

[0054] A hydrogen-bonded aromatic amide molecular cage compound PyR1, whose structural formula is shown in Formula (Ⅲ):

[0055]

[0056] In Formula (Ⅲ), R is

[0057] The preparation method of the above hydrogen-bonded aromatic amide molecular cage compound includes the following steps:

[0058] S1: Weigh hydrogen-bonded oligomeric aromatic amide diamine monomer 1 (0.048 mmol, 3 eq.) and trialdehyde monomer 2 (0.032 mmol, 2 eq.) in a 25 mL Schlenk reaction tube, add 10 mL of dry dichloromethane to dissolve, and obtain the reaction solution.

[0059] The structural formulas of the hydrogen-bonded oligomeric aromatic amide diamine monomer and the trialdehyde monomer are shown as follows:

[0060]

[0061] wherein, R is

[0062] S2: Stir the reaction solution at 40 °C for 5 days. During this period, monitor the reaction process by TLC thin layer chromatography. When the raw materials are completely converted, an insoluble yellow precipitate forms in the reaction solution to obtain the reaction solution containing imine intermediate 1.

[0063] The structural formula of imine intermediate 1 is shown as follows:

[0064]

[0065] Among them, R is

[0066] S3: Weigh NaBH3CN (24.5 mg, 0.39 mmol) and dissolve it in 2 mL of methanol. Then add it to the reaction solution containing imine intermediate 1, and stir at room temperature for the reduction reaction. During the reaction, the yellow insoluble precipitate gradually dissolves, and the solution changes from yellow to light green. After 18 h of reaction, monitor the reaction progress by TLC. When imine intermediate 1 completely disappears, stop the reaction, remove the solvent by vacuum distillation to obtain the crude product.

[0067] S4: Add 30 mL of anhydrous methanol to the obtained crude product, perform solid-liquid extraction and washing twice, and then perform vacuum filtration. The filter residue is hot-dissolved in 10 mL of CH2Cl2 / MeOH (20 / 1, v / v) mixed solution, and then reprecipitated by adding 30 mL of anhydrous methanol to obtain the crude product. The crude product is recrystallized with CH2Cl2 / MeOH (1 / 1, v / v), and then vacuum filtered. The filter residue is rinsed with 30 mL of ether to obtain the hydrogen-bonded aromatic amide molecular cage compound PyR1.

[0068] Example 3:

[0069] A hydrogen-bonded aromatic amide molecular cage compound PyR2, whose structural formula is shown in Formula (IV):

[0070]

[0071] In Formula (IV), R is

[0072] The preparation method of the above hydrogen-bonded aromatic amide molecular cage compound includes the following steps:

[0073] S1: Weigh hydrogen-bonded oligomeric aromatic amide diamine monomer 1 (0.048 mmol, 3 eq.) and trialdehyde monomer 2 (0.032 mmol, 2 eq.) in a 25 mL Schlenk reaction tube, add 10 mL of dry dichloromethane to dissolve, and obtain the reaction solution.

[0074] The structural formulas of hydrogen-bonded oligomeric aromatic amide diamine monomer 1 and trialdehyde monomer 2 are shown as follows:

[0075]

[0076] Among them, R is

[0077] S2: Stir and react the reaction solution at 40 °C for 5 days. During this period, monitor the reaction process using TLC thin-layer chromatography. When the raw materials are completely converted, an insoluble yellow precipitate forms in the reaction solution, obtaining a reaction solution containing imine intermediate 1;

[0078] The structural formula of imine intermediate 1 is as follows:

[0079]

[0080] Among them, R is

[0081] S3: Weigh NaBH3CN (24.5 mg, 0.39 mmol) and dissolve it in 2 mL of methanol. Then add it to the reaction solution containing imine intermediate 1 and stir at room temperature for the reduction reaction. During the reaction, the yellow insoluble precipitate gradually dissolves, and the solution changes from yellow to light green; after 18 h of reaction, monitor the reaction process by TLC. When imine intermediate 1 completely disappears, stop the reaction and remove the solvent by vacuum distillation to obtain the crude product;

[0082] S4: Add 30 mL of anhydrous methanol to the obtained crude product, perform solid-liquid extraction and washing twice, then filter under reduced pressure. The filter residue is dissolved by heating with 10 mL of CH2Cl2 / MeOH (20 / 1, v / v) mixed solution, and then reprecipitated by adding 30 mL of anhydrous methanol to obtain the crude product; the crude product is recrystallized with CH2Cl2 / MeOH (1 / 1, v / v), filtered under reduced pressure, and the filter residue is rinsed with 30 mL of ether to obtain the hydrogen-bonded aromatic amide molecular cage compound PyR2.

[0083] Experimental example:

[0084] 1. Structure testing

[0085] Characterize the hydrogen-bonded aromatic amide molecular cage compound R1 prepared in Example 1 by 1H NMR, 13C NMR, and high-resolution mass spectrometry:

[0086] R1 (light yellow solid, 71%). 11H NMR (400 MHz, CDCl3, 298 K) δ 9.90 (s, 6H), 9.16 (s, 3H), 8.27 (d, J = 2.8 Hz, 6H), 7.81 (s, 6H), 7.72 (d, J = 8.2 Hz, 12H), 7.52 (d, J = 8.0 Hz, 12H), 6.80 (d, J = 8.8 Hz, 6H), 6.55 (s, 3H), 6.41 (dd, J = 8.7, 2.8 Hz, 6H), 4.33 (s, 12H), 4.11 (q, J = 9.1, 7.4 Hz, 12H), 3.83 (s, 18H), 2.10–1.98 (m, 6H), 1.49–1.42 (m, 48H), 0.95 (t, J = 7.4 Hz, 18H), 0.88 (t, J = 7.0 Hz, 18H);

[0087] 13 13C NMR (100 MHz, CDCl3, 298 K) δ 162.34, 160.10, 142.99, 141.89, 141.26, 140.16, 138.58, 138.15, 129.30, 128.85, 128.81, 128.50, 127.49, 124.87, 116.15, 110.90, 107.65, 105.91, 96.52, 72.78, 56.05, 49.25, 38.65, 30.16, 29.72, 28.92, 23.57, 23.05, 14.06, 10.67, 1.04;

[0088] HRMS: m / z calculated for C 168 H 198 N 12 O 18 [M + 2H] 2+ 1337.2563; found 1337.2683.

[0089] The hydrogen-bonded aromatic amide molecular cage compound PyR1 prepared in Example 2 was characterized by 1H NMR and 13C NMR:

[0090] PyR1 (pale red solid, 59%). 11H NMR (400 MHz, CDCl3, 298 K) δ 9.81 (s, 6H), 9.11 (s, 3H), 8.87 (d, J = 2.4 Hz, 6H), 8.26 (d, J = 2.8 Hz, 6H), 7.97–7.94 (m, 6H), 7.74 (s, 6H), 7.53 (d, J = 8.2 Hz, 6H), 6.77 (d, J = 8.7 Hz, 6H), 6.54 (s, 3H), 6.42 (dd, J = 8.7, 2.9 Hz, 6H), 4.51 (s, 12H), 4.12 (dd, J = 6.5, 3.4 Hz, 12H), 3.81 (s, 18H), 2.02 (t, J = 6.3 Hz, 6H), 1.56–1.29 (m, 48H), 0.97–0.84 (m, 36H).

[0091] 13 13C NMR (100 MHz, CDCl3, 298 K) δ 162.58, 147.34, 142.13, 141.38, 136.00, 128.54, 125.82, 122.45, 115.77, 72.75, 55.91, 49.60, 49.38, 49.17, 48.95, 48.74, 48.53, 48.32, 38.67, 30.10, 28.86, 23.51, 22.90, 13.86, 10.56.

[0092] The 1H NMR characterization of the hydrogen-bonded aromatic amide molecular cage compound PyR2 prepared in Example 3 is as follows:

[0093] PyR2 (light red solid, 87%). 1 1H NMR (400 MHz, CDCl3, 298 K) δ 9.97 (s, 6H), 9.11 (s, 3H), 8.85 (d, J = 2.4 Hz, 6H), 8.21 (d, J = 2.8 Hz, 6H), 7.98 (dd, J = 8.1, 2.3 Hz, 6H), 7.75 (s, 6H), 7.55 (d, J = 8.3 Hz, 6H), 6.79 (d, J = 8.8 Hz, 6H), 6.73 (s, 3H), 6.42 (dd, J = 8.8, 2.7 Hz, 6H), 4.50 (s, 12H), 4.43 (d, J = 5.2 Hz, 12H), 4.01 (t, J = 5.1 Hz, 12H), 3.85 (s, 18H), 3.70 (dd, J = 5.9, 3.5 Hz, 12H), 3.58 (ddd, J = 12.0, 5.2, 2.9 Hz, 24H), 3.47 (dd, J = 5.8, 3.4 Hz, 12H), 3.33 (s, 18H).

[0094] 2. Thermogravimetric analysis test

[0095] The three kinds of hydrogen-bonded aromatic amide molecular cage compounds R1, PyR1 and PyR2 prepared in Examples 1-3 were subjected to thermogravimetric analysis test. Figure 1 is the thermogravimetric analysis curve of the three molecular cage compounds. The test results show that the three molecular cage compounds have relatively excellent thermal stability, and their thermal decomposition temperatures are all higher than 340 °C, which is much greater than the industrial treatment conditions for radioactive iodine adsorption (150 °C).

[0096] 3. Iodine vapor adsorption experiment

[0097] The three kinds of hydrogen-bonded aromatic amide molecular cage compounds R1, PyR1 and PyR2 prepared in Examples 1-3 were used for the adsorption of iodine vapor. The temperature during adsorption was 75 °C, and the adsorption time was 4-40 h.

[0098] The iodine vapor adsorption curves of the three molecular cage compounds with time are as Figure 2 shown. The iodine adsorption capacities of PyR1 and PyR2 are greater than that of R1. It can be seen that introducing pyridine adsorption sites into the molecular cage skeleton can greatly increase its adsorption ability for iodine vapor.

[0099] Performing pseudo-first-order kinetic fitting on it, the following results are obtained:

[0100] The pseudo-first-order kinetic model is: ln(Q e -Q t ) = lnQ e -k1t, where Q e and Q t represent the adsorption amounts (wt%) at equilibrium and at time t (min), respectively; k1 (min -1 ) represents the pseudo-first-order kinetic constant.

[0101] The relevant data are summarized in Table 1 below:

[0102] Table 1 Adsorption kinetic fitting results of hydrogen-bonded aromatic amide molecular cage compounds

[0103] Parameter R1 PyR1 PyR2 <![CDATA[Q e (wt%)]]> 421.14 508.38 523.58 <![CDATA[k1(min -1 )]]> 0.00507 0.01764 0.00603 <![CDATA[R 2 > 0.98635 0.99068 0.991

[0104] Figure 3 is the pseudo-first-order kinetic fitting of the iodine vapor adsorption curves of R1, PyR1 and PyR2 with time. From Figure 3 and the data in Table 1, it can be seen that the adsorption rate of PyR1 is the largest, followed by PyR2, and the smallest is R1; while the adsorption capacity of PyR2 is the largest, followed by PyR1, and the smallest is R1.

[0105] 4. Iodine adsorption experiment in cyclohexane phase

[0106] The three kinds of hydrogen-bonded aromatic amide molecular cage compounds R1, PyR1, and PyR2 prepared in Examples 1 to 3 were used as adsorbents for iodine adsorption in the cyclohexane phase. The determination of the adsorption capacity was carried out using a cyclohexane solution of 2.5 mg / mL (10 mM) I2. Accurately weigh 4 mg of the adsorbents R1, PyR1, and PyR2 and place them in 15 mL vials respectively. Use a pipette to transfer 10 mL of the I2 cyclohexane solution to the vials containing the adsorbents, and perform two parallel groups for each adsorbent. Add a magnetic stir bar to each vial, cover the lid and tighten it, and stir at room temperature for 48 h. Dilute the supernatant 5 times and then perform ultraviolet-visible light testing. Select the absorbance at 570 nm for concentration conversion, and calculate the adsorption capacity of the adsorbent according to Equation (1):

[0107]

[0108] Where C is the adsorption capacity, V0 is the volume of the initially added I2 cyclohexane solution, and A is the absorbance of the diluted solution after adsorption at 570 nm.

[0109] The adsorption capacities of the three molecular cage compounds for iodine in the organic phase are shown in Table 2:

[0110] Table 2. Determination results of the adsorption capacity of hydrogen-bonded aromatic amide molecular cage compounds for I2 cyclohexane solution

[0111]

[0112] Comparing the adsorption capacities of R1 and PyR1, it can be seen that introducing pyridine adsorption sites into the molecular cage framework can improve the adsorption capacity of the material for iodine in the organic phase. Further, comparing the adsorption capacities of PyR1 and PyR2, it can be seen that modifying a large number of O adsorption sites in the molecular cage side chain can further improve the adsorption capacity of the material for iodine in the organic phase.

[0113] 5. KI3 adsorption experiment in the aqueous phase

[0114] The three kinds of hydrogen-bonded aromatic amide molecular cage compounds R1, PyR1, and PyR2 prepared in Examples 1 to 3 were used as adsorbents for KI3 adsorption in the aqueous phase. The determination of the adsorption capacity was carried out using an aqueous solution of 30 mg / mL KI3. Accurately weigh 4 mg of the adsorbents R1, PyR1, and PyR2 and place them in 15 mL vials respectively. Use a pipette to transfer 10 mL of the KI3 aqueous solution to the vials containing the adsorbents, and perform two parallel groups for each adsorbent. Add a magnetic stir bar to each vial, cover the lid and tighten it, and stir at room temperature for 48 h. Filter off the adsorbent solid by suction filtration, and wash it with water several times until the filtrate washed out is colorless. Combine the filtrates, titrate with 0.05 M sodium bisulfite solution, add 1 mL of 2% starch indicator when approaching the titration end point, and continue titrating until the solution changes from blue to colorless. Calculate the adsorption capacity of the adsorbent according to Equation (2):

[0115]

[0116] Where C is the adsorption capacity, V0 is the volume of the initially added aqueous KI3 solution, and V is the volume of the sodium bisulfite solution used to reach the titration end point.

[0117] The adsorption capacities of the three molecular cage compounds for aqueous KI3 were measured as shown in Table 3.

[0118] Table 3. Measurement results of the maximum adsorption capacity of molecular cage compounds for aqueous KI3

[0119]

[0120] From the data in Table 3, by comparing the adsorption capacities of R1, PyR1, and PyR2, it can be seen that introducing pyridine adsorption sites into the molecular cage framework can improve the adsorption capacity of the material for iodine in the organic phase; further, by comparing the adsorption capacities of PyR1 and PyR2, it can be seen that the aqueous phase adsorption capacity of PyR2 has not increased much, probably because water molecules form hydrogen bonds with the side chain O adsorption sites and compete with iodine.

[0121] 6. Methyl iodide vapor (CH3I) adsorption experiment

[0122] The three hydrogen-bonded aromatic amide molecular cage compounds R1, PyR1, and PyR2 prepared in Examples 1 to 3 were used for the adsorption of methyl iodide vapor (CH3I). The temperature during adsorption was 75 °C and the adsorption time was 140 h.

[0123] The iodine vapor adsorption curves of R1, PyR1, and PyR2 versus time are as Figure 4 shown. The adsorption reached equilibrium at about 50 h, and the maximum adsorption capacity of molecular cage R1 for CH3I could reach 1.93 g g -1 .

[0124] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

Use of a hydrogen-bonded aromatic amide molecular cage compound with a structural formula as shown in formula (I) in capturing radioactive element iodine, wherein the radioactive element iodine exists in the form of KI3 in the aqueous phase: （Ⅰ） In formula (I), R is or ; X is CH or N.

2. The application according to claim 1, wherein wherein X is CH and R is ; Alternatively, X is N and R is or .

3. The application according to claim 1 or 2, characterized in that, The preparation method of the hydrogen-bonded aromatic amide molecular cage compound comprises the following steps: S1: Take the hydrogen-bonded oligomeric aromatic amide diamine monomer 1 and the trialdehyde monomer 2, dissolve them in an organic solvent to obtain a reaction solution; the structural formulas of the hydrogen-bonded oligomeric aromatic amide diamine monomer 1 and the trialdehyde monomer 2 are shown as follows, where R is or ; X is CH or N; Monomer 1 Monomer 2 S2: Stir and react the reaction solution at 35 - 45 °C for 100 - 140 h to obtain a reaction solution containing imine intermediate 1; the structural formula of the imine intermediate 1 is as follows: Intermediate 1 S3: Add a reducing agent solution to the reaction solution containing imine intermediate 1, stir and react for 16 - 20 h, and remove the solvent by vacuum distillation to obtain a crude product; S4: Separate and purify the crude product to obtain the target product.

4. The application according to claim 3, characterized in that, The molar ratio of the hydrogen-bonded oligomeric aromatic amide diamine monomer 1 to the trialdehyde monomer 2 is 3:

2.

5. The application according to claim 3, wherein The organic solvent is dichloromethane.

6. The application according to claim 3, wherein The reducing agent solution is prepared by dissolving NaBH3CN in methanol.

7. The application according to claim 3, wherein The specific steps of separation and purification in S4 are as follows: Add anhydrous methanol to the crude product for solid-liquid extraction, and obtain a filter residue by vacuum filtration; thermally dissolve the filter residue with a mixed solution of dichloromethane and methanol, and then add anhydrous methanol for reprecipitation to obtain a crude product; recrystallize the crude product with a mixed solution of dichloromethane and methanol, obtain a filter residue by vacuum filtration, and wash the filter residue with ether.

8. The application according to claim 7, wherein The volume ratio of dichloromethane to methanol in the mixed solution of dichloromethane and methanol used for dissolving the filter residue is 20:1, and the volume ratio of dichloromethane to methanol in the mixed solution of dichloromethane and methanol used for recrystallization is 1:1.

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