A carbazole-maleimide alternating conjugated macrocyclic material for efficient capture of radioactive triiodide and a preparation method thereof

Abstract

The application discloses a carbazole-maleimide alternating conjugated macrocyclic material for efficient capture of radioactive triiodide and a preparation method thereof. The conjugated macrocyclic compound has a rigid pi conjugated skeleton, can be efficiently synthesized through one-step tandem condensation reaction, and can obtain two different crystal conformations (MC-Czalpha and MC-Czbeta) through crystal condition regulation. The two conformations show significant differences when adsorbing triiodide (I3 ‑ ), wherein the MC-Czalpha conformation has superfast adsorption kinetics, the rate constant can reach 5.44*10 ‑2 g·mg ‑1 ·min ‑1 , and high removal efficiency is maintained in a wide pH range, and the reuse performance is stable. The conjugated macrocyclic compound has a clear structure, excellent adsorption performance, and has a good application prospect in the fields of nuclear waste treatment, environmental remediation and iodine detection.

Description

Technical Field

[0001] This invention belongs to the fields of organic synthetic chemistry and supramolecular chemistry, specifically relating to a method for preparing a class of rhombic carbazole-maleimide conjugated macrocyclic compounds and their application as iodine adsorbents in nuclear waste treatment and environmental remediation. Background Technology

[0002] Iodine capture is crucial for nuclear waste management, chemical safety, and environmental remediation because radioactive isotopes are highly volatile, toxic, and persistent, posing threats to the ecosystem and human health. Therefore, developing highly efficient iodine adsorbents with high capacity, rapid kinetics, and stability is both a scientific challenge and a practical necessity for nuclear safety and environmental sustainability. To date, various iodine adsorbents have been developed (such as silver-loaded zeolites, activated carbon, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), conjugated macrocyclic polymers (CMPs), and porous organic polymers (POPs)). However, problems such as low structural stability, slow adsorption rates, and limited recyclability remain unresolved.

[0003] Conjugated macrocycles with rigid frameworks, well-defined pores, tunable electronic environments, and the ability to participate in various non-covalent interactions are ideal candidates for iodine adsorption. This invention utilizes charge-transfer interactions by introducing electron-rich units (e.g., carbazole) and enhances electrostatic affinity for polyiodide anions through anionic π interactions (e.g., the introduction of electron-deficient maleimides), while their inherent cavities further facilitate guest inclusion. A rhombic alternating carbazole-maleimide donor-acceptor (DA) conjugated macrocycle (MC-Cz) was designed and synthesized via a one-step tandem reaction (Perkin condensation of glyoxylate followed by imidization). MC-Cz exhibits solvent-dependent emission due to its DA structure, induced by intramolecular charge transfer (ICT), and crystallizes in two conformations (MC-Czα / β) with different aqueous I3 phases. - Adsorption kinetics. Notably, MC-Czα exhibits an adsorption kinetic density of 5.44 × 10⁻⁶. -2 g·mg -1 ·min -1 The ultrafast iodine adsorption kinetics rate is MC-Czβ (6.6 × 10⁻⁶). 3 g·mg -1 ·min -1 It is 8 times higher than that of most reported aqueous phase I3. -Conjugated adsorbents. Furthermore, MC-Czα exhibits excellent reusability and structural stability, maintaining an iodine removal efficiency of over 97% even after five adsorption-desorption cycles. This study highlights the importance of designing high-performance cyclic iodine adsorbents through conformational control for environmental applications. Summary of the Invention

[0004] This invention proposes a carbazole-maleimide alternating conjugated macrocyclic material for efficient capture of radioactive triiodides. The unique molecular conformation and electronic structure enable the macrocyclic molecule to exhibit ultrafast adsorption kinetics and high adsorption capacity for iodine species. The iodine capture efficiency can be optimized based on the adsorption performance differences of different conformations. The stable adsorption capacity of the macrocyclic molecule for radioactive iodine has significant application potential in fields such as nuclear waste treatment and environmental remediation.

[0005] This invention also proposes a class of rhombic alternating carbazole-maleimide donor-acceptor conjugated macrocyclic molecules.

[0006] This invention also proposes a method for preparing a class of rhombic alternating carbazole-maleimide donor-acceptor conjugated macrocyclic molecules.

[0007] The present invention also proposes the application of the above-mentioned rhomboid alternating carbazole-maleimide donor-acceptor conjugated macrocyclic molecule.

[0008] In a first aspect, this invention proposes a class of donor-acceptor conjugated macrocyclic molecules based on carbazole-maleimide, the structure of which comprises two N-alkyl-substituted carbazole units as electron donors (D), four maleimide units as electron acceptors (A), and two benzene ring units bridging each other to form a rhombic macrocyclic structure with a rigid π-conjugated backbone. R1 and R2 are independently selected from C1-C16 straight-chain or branched alkyl groups; preferably, R1 is pent-3-yl and R2 is n-butyl. Its general structural formula is:

[0009] Preferably, the carbazole-maleimide donor-acceptor conjugated macrocycle has the following structural formula:

[0010] The macrocyclic molecule can exist stably in at least two different crystal conformations, and in particular, it can be selectively obtained by controlling the crystallization conditions: Conformation MC-Czα: It has an asymmetric rectangular geometric structure with the N-alkyl chains of the two carbazole units aligned in the same direction; Conformation MC-Czβ: It has a symmetrical saddle-shaped geometry with the N-alkyl chains of the two carbazole units arranged in opposite directions.

[0011] Preferably, the conformation MC-Czα has superior iodine adsorption kinetics.

[0012] Furthermore, the conjugated macrocyclic compound can exist in at least two different crystal conformations, including a first conformation MC-Czα and a second conformation MC-Czβ; wherein, the molecule of the first conformation MC-Czα has an asymmetrically twisted rectangular geometry, and the N-substituted alkyl chains of the two carbazole units are oriented in the same direction; the molecule of the second conformation MC-Czβ has an approximately symmetrical saddle-shaped geometry, and the N-substituted alkyl chains of the two carbazole units are oriented in opposite directions, and its structural formula is as follows:

[0013] A method for controlling the crystal conformation of the conjugated macrocyclic compound includes the following steps: 1) Crystals of the first conformation MC-Czα are obtained by slowly diffusing a poor solvent into a good solvent solution containing the macrocyclic compound, wherein the good solvent is dichloromethane or chloroform and the poor solvent is methanol; 2) Crystals of the second conformation MC-Czβ are obtained by solvothermal reaction of a mixed solvent system containing the macrocyclic compound under sealed conditions, wherein the mixed solvent contains acetonitrile and methanol.

[0014] A second aspect of the present invention provides a method for preparing the conjugated macrocyclic molecule as described above, comprising the following steps: S1: N-alkylcarbazole and chloroacetaldehyde ester were subjected to Friedel-Crafts acylation reaction under Lewis acid catalysis to obtain the intermediate N-alkylcarbazole-3,6-diethylene glycol diester. S2: The diester obtained in step S1 is hydrolyzed under alkaline conditions and then acidified to obtain the key intermediate N-alkylcarbazole-3,6-diethylene glycol acid; S3: The diketo acid obtained in step S2 is reacted with an aromatic diacetic acid in an inert organic solvent in the presence of an acid anhydride and an organic base to undergo a condensation cyclization reaction, followed by Perkin condensation and imidization reactions to obtain the target macrocyclic compound.

[0015] Preferably, the aromatic diacetic acid in step S3 is 1,4-phenylenediacetic acid, the acid anhydride is acetic anhydride, the organic base is triethylamine, and the inert organic solvent is tetrahydrofuran.

[0016] As a preferred preparation example, the method can be specifically implemented as follows: 1) N-Butylcarbazole and oxaloyl chloride monoethyl ester were dissolved in dichloromethane, and aluminum trichloride was added in batches under ice bath conditions. The reaction was allowed to return to room temperature for 2-6 hours. After the reaction was completed, the mixture was quenched with ice water, and purified by extraction, drying and column chromatography to obtain the diethyl ester intermediate.

[0017] 2) Dissolve the diethyl ester in ethanol, add an aqueous sodium hydroxide solution, and stir at room temperature for 4-12 hours to complete the hydrolysis; then acidify to pH 1-2, filter, wash and dry to obtain the diketo acid intermediate.

[0018] 3) The above diketo acid and 1,4-phenylenediacetic acid were dissolved in tetrahydrofuran and heated under reflux. A mixture of acetic anhydride and triethylamine was added dropwise under an inert atmosphere, and the reaction was continued under reflux for 48-96 hours. Then 3-aminopentane was added, and the reaction was refluxed again for 48-96 hours. The reaction solution was acid washed, extracted, dried, concentrated, and purified by column chromatography to obtain the target macrocyclic compound MC-Cz.

[0019] Preferably, in step 1), the molar ratio of N-butylcarbazole, oxaloyl chloride monoethyl ester, and aluminum trichloride is approximately 1:3:2.5; in step 3), the molar ratio of diketo acid, 1,4-phenylenediacetic acid, acetic anhydride, and triethylamine is approximately 1:1:15:10, and the molar ratio of 3-aminopentane to diketo acid is approximately 20:1.

[0020] In a third aspect, the invention proposes the application of the conjugated macrocyclic molecule as an iodine adsorbent, particularly for capturing triiodine ions (I3) in aqueous or gas phases. - Applications of macrocyclic molecules, particularly their MC-Czα conformation, in the form of powders, molded articles, or supported materials, for the treatment of iodine-containing nuclear waste liquids, radioactive waste gases, or iodine-contaminated environmental water bodies.

[0021] Furthermore, the iodine adsorbent is in contact with the iodine-containing medium; the iodine-containing medium includes I3... - An aqueous solution, a gas containing iodine vapor, or an organic solution containing molecular iodine are used for contact. After contact, the iodine-loaded adsorbent is treated with a reducing eluent to achieve desorption and adsorbent regeneration. The reducing eluent is an aqueous solution of sodium thiosulfate.

[0022] Furthermore, the adsorbent is effective against triiodide anions (I3) in the aqueous medium. - Adsorbents exhibit adsorption properties, with the adsorbent in the first conformation (MC-Czα) exhibiting faster adsorption kinetics than the adsorbent in the second conformation (MC-Czβ).

[0023] The beneficial effects of this invention include: 1. Excellent adsorption performance: The macrocyclic molecule (especially the MC-Czα conformation) exhibits excellent adsorption properties for I3. - The adsorption rate constant can reach 5.44 × 10⁻⁶. -2 g·mg -1 ·min -1 It belongs to the category of ultrafast adsorption materials and has a high adsorption capacity (e.g., adsorption capacity for iodine vapor > 0.40 g·g).-1 ).

[0024] 2. Good stability and cycle performance: The material is stable in a wide pH range (2-9) and can maintain the integrity of its structure and adsorption efficiency (>97%) after at least 5 adsorption-desorption cycles.

[0025] 3. Clear structure-activity relationship and adjustable performance: For the first time, by controlling the crystal conformation of the same macrocyclic molecule (MC-Czα and MC-Czβ), significant regulation of adsorption kinetics was achieved (the rate difference is about 8 times), providing a new approach for the directional design of adsorption materials through crystal engineering.

[0026] 4. The synthesis route is simple and efficient: it adopts a one-pot series reaction with few steps and mild conditions, which is suitable for large-scale preparation.

[0027] 5. Wide range of applications: This material has significant application value in nuclear waste treatment, environmental iodine pollution remediation, and potential iodine sensing. Attached Figure Description

[0028] Figure 1 The image shows the 1H NMR spectrum of compound 1. Figure 2 The carbon NMR spectrum and hydrogen NMR spectrum of compound 1 are shown. Figure 3 The image shows the proton NMR spectrum of compound 2. Figure 4 The carbon NMR spectrum and hydrogen NMR spectrum of compound 2 are shown below. Figure 5 The image shows the 1H NMR spectrum of compound 3. Figure 6 The carbon NMR spectrum and hydrogen NMR spectrum of compound 3 are shown below. Figure 7 The 1H NMR spectrum of compound MC-Cz; Figure 8 The carbon NMR spectrum and hydrogen NMR spectrum of compound MC-Cz are shown below. Figure 9 The mass spectrometry and nuclear magnetic resonance (NMR) spectrum of compound MC-Cz is shown below. Figure 10 The structures of MC-Czα and MC-Czβ; Figure 11 (a) Photographs of MC-Czα adsorbing iodine aqueous solution at different times; (b) Photograph of the adsorbed solution after filtration through a 0.22 μm membrane filter; Figure 12 (a) Photographs of MC-Czβ adsorbing iodine aqueous solution at different times; (b) Photograph of the adsorbed solution after filtration through a 0.22-micron membrane filter; Figure 13The adsorption properties of MC-Czα and MC-Czβ are shown in (a, b). - (0.15 mmol per liter of water) UV-Vis absorption spectrum over time, inset: I3 - Photos showing color changes; Figure 14 The nuclear magnetic resonance spectra of MC-Cz and the recovered MC-Czα are shown. Figure 15 For from I3 - UV-Vis spectrum of MC-Czα recovered from @MC-Czα after 5 cycles in dynamic adsorption experiment; Figure 16 For (a) MC-Czα and I3 - XPS spectra of @MC-Czα; (b) I3 - High-resolution I 3d spectrum of @MC-Czα. Detailed Implementation

[0029] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or according to the manufacturer's recommendations. Unless otherwise specified, the raw materials and reagents used are all commercially available from conventional markets. Example 1

[0030] Synthesis of macrocyclic compound MC-Cz: Sodium hydroxide solid (4.2 g) was suspended in 20 mL of dimethyl sulfoxide (DMSO). 9H-carbazole (2 g) was added to the mixture, and the resulting solution was stirred at room temperature for 0.5 h. Subsequently, 1-bromobutane (1.5 mL, density 1.28 g / mL) was added to the solution, and the reaction mixture was stirred at room temperature for another 12 h. The reaction mixture was poured into 100 mL of deionized water, and the resulting precipitate (compound 1) was collected by vacuum filtration. Product N-butylcarbazole: 2.6 g (molecular weight 223.32 g / mol, 11.64 mmol, yield 97.3%).

[0031] 1 H NMR spectral analysis as follows Figure 1As shown (400 MHz, Chloroform-d), δ 8.14 (dt, J = 7.8, 1.0 Hz, 2H), 7.53 - 7.43 (m, 4H), 7.26 (ddd, J = 7.9, 6.9, 1.2 Hz, 2H), 4.35 (t, J = 7.2 Hz, 2H), 1.95 - 1.85 (m, 2H), 1.50 - 1.39 (m, 2H), 0.99 (t, J = 7.4 Hz, 3H). 13 C NMR spectral analysis as follows Figure 2 The values ​​shown (101 MHz, Chloroform-d) are δ 140.54, 125.65, 122.91, 120.44, 118.79, 108.76, 42.88, 31.22, 20.67, 13.99. Under nitrogen protection, N-butylcarbazole (2.0 g) was dissolved in dry dichloromethane (100 mL) and cooled in an ice-water bath. With stirring, oxaloyl chloride monoethyl ester (7.64 mL) and anhydrous aluminum trichloride (4.78 g) were slowly added sequentially. The ice bath was removed, and the reaction mixture was allowed to react at room temperature for 4 hours. The reaction mixture was quenched in 2 M hydrochloric acid aqueous solution (200 mL) and extracted with dichloromethane (3 × 50 mL). The organic phases were combined, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: dichloromethane / petroleum ether = 3:1, v / v) to give the intermediate N-butylcarbazole-3,6-diethyl ketone acid ethyl ester (compound 2) as a yellow solid (yield approximately 91%).

[0032] 1 H NMR spectral analysis as follows Figure 3 Shown (400 MHz, Chloroform-d) δ 8.85 (dd, J = 1.7,0.6 Hz, 2H), 8.26 (dd, J = 8.7, 1.7 Hz, 2H), 7.55 (dd, J = 8.7, 0.6 Hz, 2H), 4.56 (q, J = 7.1 Hz, 4H), 4.41 (t, J = 7.2 Hz, 2H), 1.91 (tt, J = 7.5, 6.4Hz, 2H), 1.51 (t, J = 7.1 Hz, 6H), 1.46-1.37 (m, 2H), 0.99 (t, J = 7.4 Hz, 3H). 13 C NMR spectral analysis as follows Figure 4The values ​​shown (101 MHz, Chloroform-d) are δ 185.61, 164.38, 144.97, 128.74, 125.21, 124.37, 123.05, 109.76, 62.38, 43.58, 30.97, 20.42, 14.18, 13.75. The above-mentioned ethyl N-butylcarbazole-3,6-diacetate (0.42 g) was dissolved in ethanol (10 mL), and 7.5 M sodium hydroxide aqueous solution (2.0 mL) was added. After stirring at room temperature for 6 hours, the reaction solution was poured into ice water (30 mL), and the pH was adjusted to 1-2 with 6 M hydrochloric acid. A yellow precipitate precipitated, which was filtered under reduced pressure, washed with water, and dried under vacuum at 60 °C overnight to give the intermediate N-butylcarbazole-3,6-diacetate (compound 3), a yellow solid, which could be used in the next step without further purification, with a yield of 93.6%.

[0033] 1H NMR spectral analysis as follows Figure 5 The 13C NMR spectrum analysis (400 MHz, DMSO-d6) shows the following values: δ 9.03 (d, J = 1.8 Hz, 2H), 8.12 (dd, J = 8.8, 1.8 Hz, 2H), 7.94 (d, J = 8.8 Hz, 2H), 4.56 (t, J = 7.1 Hz, 2H), 1.81 (p, J = 7.3 Hz, 2H), 1.32 (q, J = 7.6 Hz, 2H), 0.89 (t, J = 7.4 Hz, 3H). The wavelengths are as follows: Figure 6 The values ​​shown (101 MHz, DMSO-d6) are δ 188.55, 145.07, 128.47, 124.87, 124.77, 122.81, 111.26, 43.28, 31.01, 20.11, 14.06. The obtained N-butylcarbazole-3,6-diethyl ketoacid (1.29 g) and 1,4-phenylenediacetic acid (0.68 g) were dissolved in dry tetrahydrofuran (700 mL) and heated to reflux. Under argon protection, a mixture of acetic anhydride (5.0 mL) and triethylamine (4.7 mL) dissolved in tetrahydrofuran (50 mL) was added dropwise to the reflux suspension. The mixture was stirred vigorously and refluxed for 3 days. Then 3-aminopentane (8.2 mL) was added, and the reaction was continued at reflux temperature of 80 °C for 3 days. The reaction solution was concentrated under reduced pressure to about 200 mL, cooled to room temperature, and 5 wt% hydrochloric acid aqueous solution (200 mL) was added. The mixture was extracted with dichloromethane (2 × 200 mL), the organic phases were combined, and dried over anhydrous sodium sulfate. After removing the solvent under reduced pressure, the residue was purified by silica gel column chromatography (eluent: dichloromethane / petroleum ether = 3:2, v / v) to give the target product, a rhombic alternating carbazole-maleimide conjugated macrocyclic compound (MC-Cz), as an orange solid (yield approximately 15.3%).

[0034] 1 H NMR spectral analysis as follows Figure 7 Shown (400 MHz, Chloroform-d) δ 8.02 (d, J = 1.7 Hz, 4H), 7.75 (s, 8H), 7.63 (dd, J = 8.6, 1.6 Hz, 4H), 7.38 (d, J = 8.6 Hz, 4H), 4.25 (t, J = 7.2 Hz, 4H), 4.03 (tt, J = 9.9, 5.5 Hz, 4H), 2.04 (ddt, J =16.9, 14.6, 7.5 Hz, 9H), 1.88 - 1.78 (m, 13H), 1.39 (q, J = 7.6 Hz, 4H), 0.94(t, J = 7.4 Hz, 30H). 13 C NMR spectral analysis as follows Figure 8 The following HRMS (m / z) plots (101 MHz, Chloroform-d) show the following values: δ 171.42, 141.51, 136.71, 131.03, 130.32, 129.55, 128.43, 122.88, 121.95, 120.19, 109.41, 56.09, 43.15, 31.06, 25.31, 20.46, 13.78, 11.40. Figure 9 As shown: [M] + calcd for C 80 H 82 N6O8 +1254.6254, found 1254.6189. The reaction formula is shown below:

[0035] Example 2 Controllable preparation of crystal conformations MC-Czα and MC-Czβ.

[0036] The MC-Cz compound obtained in Example 1 was dissolved in dichloromethane to prepare a solution with a concentration of 5 mg / mL. After filtration, the filtrate was placed in a glass sample tube, and methanol was slowly added above it as a poor solvent to form a clear interface. After standing at room temperature for about one week, orange blocky crystals grew at the interface and at the bottom of the tube. The crystals were collected by filtration, and X-ray single-crystal diffraction analysis confirmed that it was the MC-Czα conformation. The crystal structure showed that its molecule had an asymmetric rectangular geometry, and the butyl chains of the two carbazole units were aligned in the same direction.

[0037] A separate sample of the MC-Cz compound was dissolved in a mixed solvent of methanol and acetonitrile (volume ratio 1:3). The solution was transferred to a stainless steel reactor lined with polytetrafluoroethylene (PTFE), sealed, and placed in an oven at 100°C for 48 hours, followed by a programmed cooling to room temperature at a rate of 5°C per hour. Upon opening the reactor, yellow blocky crystals were obtained. These were collected by filtration, and X-ray single-crystal diffraction analysis confirmed that the MC-Czβ conformation was present. The crystal structure showed a symmetrical saddle-shaped geometry with the butyl chains of the two carbazole units arranged in anti-alignment. Figure 10 . Example 3

[0038] MC-Czα and MC-Czβ in aqueous solution of triiodide ions (I3) - The adsorption performance of ).

[0039] The MC-Czα and MC-Czβ single crystals obtained in Example 2 were ground into uniform powders and activated by vacuum drying at 373 K (about 100 °C) for 10 hours.

[0040] Accurately weigh 5.0 mg of activated MC-Czα and MC-Czβ powder respectively, and place them in separate 10 mL glass sample vials. Add 5.0 mL of 0.15 mM I3 to each vial. - Aqueous solution (prepared from potassium iodide and elemental iodine in a molar ratio of 10:1). The sample vials were kept at room temperature and continuously stirred magnetically. Results are as follows: Figure 11 , Figure 12 As shown.

[0041] Samples were taken at predetermined time intervals (e.g., 0, 1, 2, 3, 5, 7, 10, 15, 20, 25, 30 minutes) using a UV-Vis spectrometer. After filtration through a 0.22 μm filter membrane, the absorbance of the filtrate was immediately measured at 288 nm. The remaining I3 in the solution was calculated using a pre-established standard curve. - The concentration was determined, and the adsorption capacity of the adsorbent at different times was calculated using the formula. The results are as follows: Figure 13 As shown.

[0042] Experimental data show that MC-Czα has an effect on I3 within 1 minute after addition. - The removal rate reached 82%; after stirring for 30 minutes, the removal rate exceeded 98%. Its adsorption kinetics data conformed to a pseudo-second-order kinetic model, and the fitted rate constant (k²) was 5.44 × 10⁻⁶. -2 g·mg -1 ·min -1 Under identical conditions, the adsorption process of MC-Czβ was significantly slower, with a removal rate of approximately 62.5% at 30 minutes, and its pseudo-second-order adsorption rate constant (k²) was 6.65 × 10⁻⁶. -3 g·mg -1 ·min -1 The adsorption rate of MC-Czα is approximately 8 times that of MC-Czβ. Example 4

[0043] Cyclic stability of MC-Czα Take 50 mg of activated MC-Czα powder and add it to 50 mL of 0.15 mM I3 solution. - In an aqueous solution, the mixture was stirred at room temperature for 1 hour to reach adsorption saturation. The adsorbed solid material was then separated by filtration.

[0044] The iodine-loaded solid material was immersed in a 0.1 M sodium thiosulfate (Na2S2O3) aqueous solution and gently stirred to desorb the iodine. The solid was then thoroughly washed with ultrapure water until neutral and dried under vacuum at 60 °C to obtain the regenerated MC-Czα material.

[0045] The regenerated material was used in the next adsorption experiment, repeating the "adsorption-desorption-washing-drying" steps. After 5 consecutive cycles, MC-Czα showed its effect on I3. - The removal efficiency remains above 97%. Figure 15 Comparison of the 1H NMR spectra of the material before and after cycling revealed no shifts in characteristic peaks or the appearance of new peaks, indicating that its chemical structure remained intact during cycling. Figure 14 As shown.

[0046] X-ray photoelectron spectroscopy (XPS) analysis was performed on the MC-Czα sample after initial adsorption saturation. Characteristic signals of iodine were observed in the full spectrum. High-resolution scanning and peak fitting of the iodine (I3d) region revealed two sets of spin-orbit doublets: peaks with binding energies at 619.68 eV and 630.74 eV were attributed to triiodide ions (I3). - The peaks with binding energies at 617.52 eV and 628.88 eV are attributed to pentaiodine ions (I3). - This indicates that charge-transfer interactions occur between the macrocyclic framework and iodine species during adsorption, and polyiodides may be formed. Figure 16 As shown.

[0047] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A class of carbazole-maleimide donor-acceptor conjugated macrocyclic compounds based on rhombic alternation, characterized in that: The general molecular structural formula of the carbazole-maleimide donor-acceptor conjugated macrocyclic compound is as follows: ； R1 and R2 are independently selected from C1-C8 straight-chain or branched alkyl groups.

2. The conjugated macrocyclic compound according to claim 1, characterized in that, R1 is pentyl-3-yl and R2 is butyl.

3. The conjugated macrocyclic compound according to claim 1 or 2, characterized in that, The conjugated macrocyclic compound can exist in at least two different crystal conformations, including a first conformation MC-Czα and a second conformation MC-Czβ; wherein, the molecule of the first conformation MC-Czα has an asymmetrically twisted rectangular geometry, and the N-substituted alkyl chains of the two carbazole units are oriented in the same direction; the molecule of the second conformation MC-Czβ has an approximately symmetrical saddle-shaped geometry, and the N-substituted alkyl chains of the two carbazole units are oriented in opposite directions, and its structural formula is as follows: 。 4. The method for preparing the conjugated macrocyclic compound according to claim 3, characterized in that: Includes the following steps: 1) Under Lewis acid catalysis, N-alkylcarbazole is subjected to Friedel-Crafts acylation reaction with haloacetylacetate to obtain carbazole-3,6-diacetate ethyl ester intermediate; 2) The intermediate was hydrolyzed under alkaline conditions, followed by acidification, to obtain the corresponding carbazole-3,6-diacetylene acid; 3) The carbazole-3,6-diethyl keto acid obtained in step (2) is reacted with aromatic diacetic acid in an inert organic solvent in the presence of an acid anhydride and an organic base to carry out a condensation cyclization reaction, followed by Perkin condensation and imidization reaction to obtain the conjugated macrocyclic compound.

5. The method according to claim 4, characterized in that, The aromatic diacetic acid mentioned in step (3) is 1,4-phenylenediacetic acid, the acid anhydride is acetic anhydride, the organic base is triethylamine, and the inert organic solvent is tetrahydrofuran.

6. A method for controlling the crystal conformation of the conjugated macrocyclic compound as described in claim 3, characterized in that: Includes the following steps: 1) Crystals of the first conformation MC-Czα are obtained by slowly diffusing a poor solvent into a good solvent solution containing the macrocyclic compound, wherein the good solvent is dichloromethane or chloroform and the poor solvent is methanol; 2) Crystals of the second conformation MC-Czβ are obtained by solvothermal reaction of a mixed solvent system containing the macrocyclic compound under sealed conditions, wherein the mixed solvent contains acetonitrile and methanol.

7. An iodine adsorbent, characterized in that, It comprises a conjugated macrocyclic compound as described in any one of claims 1 to 3, or a conjugated macrocyclic compound having a specific crystal conformation obtained by the method according to claim 6.

8. The iodine adsorbent according to claim 7, characterized in that, The adsorbent targets triiodide anions (I3) in the aqueous medium. - It exhibits adsorption properties, wherein the adsorbent present in the first conformation MC-Czα exhibits faster adsorption kinetics than the second conformation MC-Czβ.

9. A method for capturing or removing iodine from an iodine-containing medium, characterized in that, The iodine adsorbent as described in claim 7 or 8 is contacted with an iodine-containing medium; the iodine-containing medium includes I3-containing media. - The adsorbent can be in an aqueous solution, a gas containing iodine vapor, or an organic solution containing molecular iodine. After contact, the iodine-loaded adsorbent is treated with a reducing eluent to achieve desorption and adsorbent regeneration. The reducing eluent is an aqueous solution of sodium thiosulfate.

10. The use of the conjugated macrocyclic compound as described in any one of claims 1 to 3 in the preparation of iodine capture materials for nuclear waste treatment, environmental remediation or chemical safety.

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