Organic-inorganic hybrid monolithic materials containing bipyridine and preparation of their separation from cb[5] and cb[7]

Abstract

The present application relates to a kind of organic-inorganic hybrid monolithic material containing bipyridine and preparation and CB [5] and CB [7] separation. Specifically, first using tetramethoxysilane and 3-chloropropyl trimethoxysilane as silane reagent, urea and polyethylene glycol-10000 as porogen, after hydrolysis reaction of silane reagent, copolymerization is carried out into the silica gel monolithic material with chlorine atom, then through electrophilic substitution reaction modification 4,4-bipyridine, obtain a kind of organic-inorganic hybrid monolithic material containing bipyridine. Using the difference between CB [5], CB [7] and host-guest interaction of bipyridine, the selective separation of CB [5] and CB [7] is realized. The method used in the present application process is simple, organic solvent is used less, green and environmental protection, can be applied to large-scale preparation high-purity CB [5] and CB [7], with good commercialization prospect.

Description

Technical Field

[0001] The synthetic products of cucurbituril (CB[n]) are generally composed of a series of homologues, including cucurbituril[5] (CB[5]), cucurbituril[6] (CB[6]), cucurbituril[7] (CB[7]), and cucurbituril[8] (CB[8]). Among them, CB[6] and CB[8] can be separated by simple differences in solubility. However, due to their physical and chemical similarities, CB[5] and CB[7] are difficult to separate by conventional methods. This invention adopts a "supramolecular affinity chromatography" strategy, using hybrid monolithic materials as adsorbents, and utilizes the differences in host-guest interactions between CB[5], CB[7] and bipyridine to achieve selective separation of CB[5] and CB[7]. Background Technology

[0002] CB[n] is a macrocyclic molecule composed of glycourea units linked by methylene bridges. It is generally composed of a series of homologues of CB[5], CB[6], CB[7] and CB[8], and has a rigid and highly symmetrical structure. Their unique molecular structure endows them with extraordinary molecular recognition ability: their hydrophobic cavity and the electronegative carbonyl groups at the two ports can bind different guests through a variety of non-covalent interactions. Therefore, CB[n] is widely used in perovskite solar cells, adsorption separation, room temperature phosphorescence, and biomolecular science. Due to its small hydrophobic cavity, CB[5] can only bind certain gas molecules or cations: by using the hydrophobic cavity of CB[5] to suppress oxygen vacancies in SnO2 and suppress particle aggregation, a highly efficient and stable perovskite solar cell can be realized. (Literature 1, Z. Long, C. Peng, K. Dong, H. Jiang, M. Zhu, W. Yan, Y.Dong, W. Jiang, L. Wen, X. Jiang, Z. Zhou, Supramolecular cucurbit[5]urilmodulates the buried SnO2 / perovskite interface for efficient and stable perovskite solar cells, Advanced Functional Materials,34 (2024), 2408818.) CB[7] Because its larger cavity can not only encapsulate aromatic compounds to form room temperature phosphorescent materials with extended lifetime, but also use its dynamic regulation ability to control the binding of guest molecules and realize the reversible regulation of DNA helical structure. (Reference 2, S.Wang, J. Wang, G. Xu, L. Wei, B. Fu, L. Wu, Y. Song, X. Yang, C. Li, S. Liu, X. Zhou, The cucurbit[7]uril‐based supramolecular chemistry for reversible B / Z‐DNA transition, Advanced Science 5 (2018), 1800231.) CB[5] and CB[7] are extremely difficult to prepare, but their applications are very wide and their supply is limited; at the same time, the high-purity products are expensive (at Aladdin Reagent Company, CB[5]: RMB 12,000 / g, CB[7]: RMB 17,000 / g), and their high purity is a key prerequisite for ensuring the performance of subject-object recognition, supporting drug delivery, sensing detection and functional materials and other core applications. Traditional separation methods are cumbersome, costly and difficult to scale up. Kim proposed a method to separate CB[n] based on the difference in solubility: CB[6] and CB[8] have a large difference in solubility in hydrochloric acid solution, so they can be separated well; however, the solubility of CB[5] and CB[7] is similar in any solution, so separation based on the difference in solubility is limited. (Literature 3, K. Jaheon, J. In-Sun, K. Soo-Young, L. Eunsung, K. Jin-Koo, S. Shigeru, Y. Kentaro, K. Kimoon, Newcucurbituril homologues: Syntheses, isolation, characterization, and X-raycrystal structures of cucurbit[n]uril (n=5, 7, and 8), Journal of the American Chemical Society122 (2000), 540-541.) Scherman's team proposed a novel separation strategy that introduces a compound with an alkylimidazolium ionic liquid guest of the [Cnmim]Br type. This compound can selectively bind to CB[7] to form a solid ionic complex and finally obtain high-purity CB[7]. However, this method is complex and time-consuming. (Reference 4, D. Jiao, N. Zhao, OAScherman, A “green” method for isolation of cucurbit[7]uril) via a solid statemetathesis reaction, Chemical Commol / Lunications 46 (2010), 2007-2009.) Sletten designed a guest molecule called carborane, whose binding affinity with the host molecule can be regulated by chemical reaction, thus making the successful recovery and reuse of CB[7] possible. However, due to its complex structure, difficult preparation and high production cost, carborane is difficult to apply on a large scale, which limits the practical promotion of this method. (Reference 5, A. Kataki-Anastasakou, JC Axtell, S. Hernandez, RM Dziedzic, GJ Balaich, ALRheingold, AM Spokoyny, EM Sletten, Carborane guests for cucurbit[7]urilfacilitate strong binding and on-demand removal, Journal of the American Chemical Society 142 (2020), 20513-20518.) These exploratory studies inspire us to separate guest molecules by the selectivity differences of CB[5] and CB[7]. Affinity chromatography has the characteristics of high affinity and high selectivity, and plays an important role in the preparation and purification of high-purity samples. This application proposes a method for separating CB[5] and CB[7] based on hybrid monolithic materials of supramolecular affinity chromatography. It is simple to operate, has mild conditions, and has good scale-up potential. It can significantly reduce the preparation cost of high-purity CB[5] and CB[7], and has important scientific research value and commercial prospects. Summary of the Invention

[0003] The purpose of this invention is to provide a method for selectively separating CB[5] and CB[7] on hybrid monolithic materials using a "supramolecular affinity chromatography" strategy based on molecular recognition.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: First, measure 5-6 mL of 0.01-0.03 mol / L acetic acid solution into a container. Weigh 500-600 mg of urea and 400-450 mg of polyethylene glycol-10000 into the same container and mix and dissolve them. Then, measure 1.5-2 mL of tetramethoxysilane and 0.5-0.7 mL of 3-chloropropyltrimethoxysilane into the same container. Hydrolyze the mixture under ice bath conditions (-10-0 °C) for 3-6 h, then react it in a water bath at 50-70 °C for 12-20 h. Finally, wash away the pore-forming agent with a 40-60% (v / v) ethanol aqueous solution and dry to obtain a monolithic silica material with chlorine atoms. Weigh 420-480 mg of 4,4-bipyridine and dissolve it in 10-20 mL of acetonitrile solution. Add 320-380 mg of the monolithic silica material with chlorine atoms and react it at 50-100 °C for 12-20 h. h, and finally washed with an aqueous ethanol solution of 40-60% by volume, and dried to obtain an organic-inorganic hybrid monolithic material containing bipyridine.

[0005] ① Weigh 50-100 mg of the organic-inorganic hybrid monolithic material containing bipyridine as described in claim 3 into a centrifuge tube; ② Equilibration: Measure 2-4 mL of 45-55% acetonitrile aqueous solution into a centrifuge tube, shake (200-400 rpm) for 30-60 min, and centrifuge to remove the supernatant. Repeat the operation 2-5 times; ③ Sample loading: Measure 4-6 mL of crude product solution containing CB[5] and CB[7] (the crude separation product in the synthesis process, dissolved in 20-200 mmol / L ammonium acetate solution, with a concentration of 1-3 mg / mL) into the above centrifuge tube, shake (200-400 rpm) for 12-20 h, and centrifuge to collect the flow-through liquid containing CB[5]; ④ Washing: Measure 2-10 mL of 70-120 mmol / L ammonium acetate solution (dissolved in 30-70% methanol aqueous solution) into the above centrifuge tube, shake (200-400 rpm) for 30-60 min. After min, centrifuge to remove the eluent containing impurities such as CB[6] (residual from the coarse separation process), and repeat the rinsing operation 3 times; ⑤ Elution: Measure 1~1.2 M ammonium acetate aqueous solution into the above centrifuge tube, shake (200~400 rpm) for 30~60 min, centrifuge to collect the eluent of CB[7], repeat the elution operation 2~5 times to obtain the eluent; collect the flow-through liquid and the eluent separately and combine them, and dry them separately to obtain solid samples of CB[5] and CB[7].

[0006] The present invention has the following advantages:

[0007] 1. The operation process is simple and requires a small amount of organic reagents, making it green and environmentally friendly; 2. The separated products have high purity; 3. It can be applied to the large-scale preparation of high-purity CB[5] and CB[7]. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of a method for selectively separating CB[5] and CB[7] on a hybrid monolithic material using a "supramolecular affinity chromatography" strategy based on molecular recognition.

[0009] Figure 2 This is a physical image of Monolith-Bp-1 in Example 1.

[0010] Figure 3 The infrared spectrum of Monolith-Bp-1 in Example 1 is shown.

[0011] Figure 4 The MALDI-TOF MS spectrum of the crude product sample containing CB[5] and CB[7].

[0012] Figure 5 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-1 in Example 1 is shown.

[0013] Figure 6 The MALDI-TOF MS spectrum of the eluent of Monolith-Bp-1 in Example 1 is shown.

[0014] Figure 7 This is a physical image of Monolith-Bp-2 in Example 2.

[0015] Figure 8 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-2 in Example 2 is shown.

[0016] Figure 9 The image shows the MALDI-TOF MS spectrum of the eluent of Monolith-Bp-2 in Example 2.

[0017] Figure 10 This is a physical image of Monolith-Bp-1 in Example 3.

[0018] Figure 11 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-1 in Example 3 is shown.

[0019] Figure 12 The MALDI-TOF MS spectrum of the eluent of Monolith-Bp-1 in Example 3 is shown.

[0020] Figure 13 This is a physical image of Monolith-Bp-3 from Comparative Example 1.

[0021] Figure 14 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-3 in Comparative Example 1 is shown.

[0022] Figure 15 The MALDI-TOF MS spectrum of the eluent of Monolith-Bp-3 in Comparative Example 1 is shown.

[0023] Figure 16 This is a physical image of Monolith-Bp-4 from Comparative Example 2.

[0024] Figure 17 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-4 in Comparative Example 2 is shown.

[0025] Figure 18 The image shows the MALDI-TOF MS spectrum of the eluent of Monolith-Bp-4 in Comparative Example 2.

[0026] Figure 19 This is a physical image of Monolith-Bp-1 from Comparative Example 3.

[0027] Figure 20 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-1 in Comparative Example 3 is shown.

[0028] Figure 21 The MALDI-TOF MS spectrum of the eluent from Monolith-Bp-1 in Comparative Example 3 is shown.

[0029] Figure 22 This is a physical image of Monolith-BVBp-1 in Comparative Example 4.

[0030] Figure 23 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-BVBp-1 in Comparative Example 4 is shown.

[0031] Figure 24 The MALDI-TOF MS spectrum of the eluent of Monolith-BVBp-1 in Comparative Example 4 is shown. Detailed Implementation

[0032] Example 1: Hybrid monolithic materials based on supramolecular affinity chromatography for the separation of CB[5] and CB[7]. Separation of samples: Crude product containing CB[5] and CB[7]: 71.2 g of glycourea and 30.1 g of paraformaldehyde were weighed into a round-bottom flask and dissolved in 110 mL of 37% hydrochloric acid. The mixture was reacted at 110 °C and 300 rpm for 24 h with mechanical stirring. The solution was then concentrated to 10 mL under reduced pressure, precipitated with 100 mL of acetone, filtered, and the filter cake (a mixture containing CB[5], CB[6], CB[7] and CB[8]) was collected. The filter cake was then dissolved in 600 mL of deionized water, stirred for 12 h, filtered, and the filtrate was collected. The process of dissolving, stirring, and filtering was repeated three times. All the filtrates were then collected and combined to obtain a crude product solution containing CB[5] and CB[7]. The solution was concentrated to 10 mL under reduced pressure and precipitated with 100 mL of acetone. The filter cake was collected. After drying, the filter cake yielded a white powdery crude product containing CB[5] and CB[7] (which contained incompletely separated CB[6] and byproducts). (Prepared by reference 6: A. Day, A. Alan P, B. Rodney J, S. Barry, Controllingfactors in the synthesis of cucurbituril and its homologues, The Journal of Organic Chemistry 66 (2001), 8094-8100.) Preparation of organic-inorganic hybrid monolithic material containing bipyridine: First, 5 mL of 0.01 mol / L acetic acid aqueous solution was measured into a container, and 600 mg of urea and 410 mg of polyethylene glycol-10000 were weighed and dissolved in the same container. Then, 1.8 mL of tetramethoxysilane and 0.6 mL of 3-chloropropyltrimethoxysilane were measured into the same container and hydrolyzed for 4 h under ice bath conditions (-5 °C). The mixture was then reacted in a water bath at 60 °C for 12 h. Finally, the porogen was washed away with 50% ethanol aqueous solution, and the material was dried to obtain a silica monolithic material containing chlorine atoms. 420 mg of 4,4-bipyridine was weighed and dissolved in 10 mL of acetonitrile solution, and 350 mg of the silica monolithic material containing chlorine atoms was added. The mixture was reacted at 50 °C for 12 h and finally washed with 50% ethanol aqueous solution. After vacuum drying at 60 °C, an organic-inorganic hybrid monolithic material containing bipyridine was obtained, named Monolith-Bp-1.

[0033] The method for separating CB[5] and CB[7] based on supramolecular affinity chromatography: ① Weigh 50 m of Monolith-Bp-1, an organic-inorganic hybrid monolith containing bipyridine, into a centrifuge tube; ② Equilibrate: Measure 2 mL of 50% acetonitrile aqueous solution into a centrifuge tube, shake (300 rpm) for 30 min, and centrifuge to remove the supernatant. Repeat the operation 3 times; ③ Load the sample: Measure 4 mL of crude product solution containing CB[5] and CB[7] (the crude separation product in the synthesis process, dissolved in 100 mmol / L ammonium acetate solution, with a concentration of 1 mg / mL) into the above centrifuge tube, shake (300 rpm) for 12 h, and centrifuge to collect the flow-through liquid containing CB[5]; ④ Wash: Measure 2 mL of 100 mmol / L ammonium acetate solution (dissolved in 50% methanol aqueous solution) into the above centrifuge tube, shake (300 rpm) for 30 min. After min, centrifuge to remove the eluent containing impurities such as CB[6] (residual from the coarse separation process), and repeat the rinsing operation 3 times; ⑤ Elution: Measure 1 M ammonium acetate aqueous solution into the above centrifuge tube, shake (300 rpm) for 30 min, centrifuge to collect the eluent of CB[7], repeat the elution operation 3 times to obtain the eluent; collect the flow-through liquid and the eluent separately and combine them, and dry them separately to obtain solid samples of CB[5] and CB[7].

[0034] Assay Method: Each component of the workflow was collected separately, including the flow-through and combined eluent. These liquids were lyophilized to a concentration of 1 mg / mL before analysis by MALDI-TOF MS (CP-Light 1000, Xiamen Kingnoahva Biotechnology Co., LTD, China). Finally, 1 μL of sample and 1 μL of DHB solution (2,5-dihydroxybenzoic acid dissolved in a mixed solution: ACN / H₂O / H₃PO₄, concentration 25 mg / mL, volume ratio 50 / 49 / 1, v / v / v) were sequentially spotted onto a MALDI plate.

[0035] Purity identification method: Find the peak intensity values ​​of the signals representing CB[5] and CB[7] and the signals containing CB[6] and by-product impurities in the mass spectrum, sum all the peak intensity values ​​to obtain the total intensity value, and then calculate the proportion of the peak intensity values ​​of CB[5] and CB[7] to the total intensity, and express it as the purity of CB[5] and CB[7].

[0036] Product characterization

[0037] Figure 2This is a picture of Monolith-Bp-1. The picture shows that the material has a uniform texture, is a white, opaque solid, and exhibits some elasticity when pressed, indicating that it has a certain degree of rigidity.

[0038] Figure 3 This is the infrared spectrum of Monolith-Bp-1. The spectrum shows a value of 1082 cm⁻¹. -1 and 795 cm -1 The absorption peaks at 3426 cm⁻¹ represent the asymmetric and symmetric stretching vibrations of the Si-O-Si bonds in the silica backbone, respectively. -1 The peak at 1632 cm⁻¹ is a characteristic peak of the Si-OH bond in the silica skeleton; the peak at 1632 cm⁻¹ is a stretching vibration peak of the C=N bond in the pyridine ring, indicating that the organic-inorganic hybrid monolithic material containing bipyridine was successfully prepared.

[0039] Evaluation results

[0040] Figure 4 The MALDI-TOF MS spectrum of the crude product sample containing CB[5] and CB[7] is shown in the figure. A high-intensity CB[5] signal peak 1 (831 Da, [CB[5]+H]) is observed in the figure. + ) and CB[7] signal peak 6 (1163 Da, [CB[7]+H] + Other signal peaks were also detected in the spectrum, which were attributed to CB[5] / CB[7] with various guests (including Na). + / K + The addition peak of / DHB), peak 2 (853 Da, [CB[5]+Na) + ), peak 3 (869 Da, [CB[5]+K] + ), peak 7 (1185 Da, [CB[7]+Na] + ), peak 8 (1201 Da, [CB[7]+K] + ), peak 9 (1298 Da, [CB[7]+DHB-OH] + In addition, two CB[6] peaks with lower abundance were observed, namely peak 4 (997 Da, [CB[6]+H]). + ), peak 5 (1019 Da, [CB[6]+Na] + This is a product that could not be removed during the coarse separation process. In the region with a relatively high mass charge, a special type of signal peak was identified, which is speculated to be the addition product of two CB[n] units, peak 10 (2181 Da, [CB[6]+CB[7]+Na]). + ) and peak 11 (2347 Da, [CB[7]+CB[7]+Na] + ).

[0041] Figure 5 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-1 in Example 1 shows a distinct CB[5] signal peak 2 (853 Da, [CB[5]+Na]). + ) and a weak CB[7] signal peak 7 (1185 Da, [CB[7]+Na] + This is because, under neutral loading conditions of 100 mmol / L NH4OAc, it can suppress the protonation of bipyridine, thereby effectively suppressing the ion-dipole interaction of CB[5], while CB[7] can still encapsulate the guest in its larger hydrophobic cavity. The flow-through liquid is collected and lyophilized to obtain high-purity solid CB[5] (>97.0%).

[0042] Figure 6 The MALDI-TOF MS spectrum of the eluent of Monolith-Bp-1 in Example 1 shows a distinct CB[7] signal peak (1201 Da, [CB[7]+K]). + Peak 9 (1298 Da, [CB[7]+DHB-OH]) + At the same time, there was no CB[5] signal peak. This is because the ion-dipole interaction of CB[5] is destroyed during the rinsing process, and CB[5] cannot be retained on the whole material and is washed off first. The hydrophobic cavity effect of CB[7] is destroyed under the elution conditions of high concentration of ammonium acetate, and CB[7] is obtained in the eluent. Collect the eluent and freeze dry to obtain high purity solid CB[7] (>99.0%).

[0043] Example 2: A method for separating CB[5] and CB[7] using hybrid monolithic materials based on supramolecular affinity chromatography

[0044] The process and conditions were the same as in Example 1, except that the mass of 4,4-bipyridine in the preparation system of the hybrid monolithic material of Example 1 was increased to 480 mg, and the rest of the preparation and modification process and conditions (preparation of organic-inorganic hybrid monolithic material containing bipyridine) were the same as in Example 1. The obtained hybrid monolithic material containing bipyridine was named Monolith-Bp-2. The supramolecular affinity chromatography process and conditions (method for separating CB[5] and CB[7] based on supramolecular affinity chromatography) were the same as in Example 1.

[0045] Product characterization

[0046] Figure 7This is a picture of Monolith-Bp-2. The picture shows that the material has a uniform texture, is a white, opaque solid, and exhibits some elasticity when pressed, indicating that it has a certain degree of rigidity.

[0047] Product Application

[0048] Monolith-Bp-2 was used to selectively separate CB[5] and CB[7]. The separation of samples and detection methods were the same as in Example 1.

[0049] Evaluation results

[0050] Figure 8 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-2 in Example 2 shows a distinct CB[5] signal peak 2 (853 Da, [CB[5]+Na]). + At the same time, there was no CB[7] signal peak. The CB[7] content in the flow-through liquid was significantly reduced compared with Example 1. This is because the increase in the guest molecule 4,4-bipyridine increases the binding sites of the material, allowing CB[7] to encapsulate more guests. The flow-through liquid was collected and lyophilized to obtain high-purity solid CB[5] (>99.0%).

[0051] Figure 9 The image shows the MALDI-TOF MS spectrum of the eluent of Monolith-Bp-2 in Example 1. A distinct CB[7] signal peak (1201 Da, [CB[7]+K]) was observed in the image. + Peak 9 (1298 Da, [CB[7]+DHB-OH]) + At the same time, there was no CB[5] signal peak. Collect the eluent and freeze-dry it to obtain high-purity solid CB[7] (>99.0%).

[0052] Example 3: A method for separating CB[5] and CB[7] using hybrid monolithic materials based on supramolecular affinity chromatography

[0053] The preparation and modification process and conditions (preparation of the organic-inorganic hybrid monolithic material containing bipyridine) were the same as in Example 1, and the resulting hybrid monolithic material containing bipyridine was named Monolith-Bp-1. The supramolecular affinity chromatography method differed from that in that the ammonium acetate concentration was reduced to 30 mmol / L under the loading conditions of Example 1, while the remaining processes and methods (methods for separating CB[5] and CB[7] based on supramolecular affinity chromatography) were the same as in Example 1.

[0054] Product characterization

[0055] Figure 10This is a picture of Monolith-Bp-1. The picture shows that the material has a uniform texture, is a white, opaque solid, and exhibits some elasticity when pressed, indicating that it has a certain degree of rigidity.

[0056] Product Application

[0057] Monolith-Bp-1 was used to selectively separate CB[5] and CB[7]. The separation of samples and detection methods were the same as in Example 1.

[0058] Evaluation results

[0059] Figure 11 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-1 in Example 3 shows a high CB[5] signal peak 2 (853 Da, [CB[5]+Na]). + Furthermore, a distinct signal peak of CB[7] (1185 Da, [CB[7]+Na]) can be observed. + Compared with Example 1, the content of CB[7] in the flow-through liquid was significantly increased. This is because the ion concentration of ammonium acetate was too low under the loading conditions of 30 mmol / L, which could not suppress the ion-dipole interaction of CB[5] and reduce the selectivity of the material for CB[7]. The flow-through liquid was collected, and lyophilization could not yield high-purity solid CB[5].

[0060] Figure 12 The MALDI-TOF MS spectrum of the eluent of Monolith-Bp-1 in Example 3 shows a distinct CB[7] signal peak (1298 Da, [CB[7]+DHB-OH]). + ), and there was no CB[5] signal peak. Compared with Example 1, the CB[7] signal peak 8 (1201 Da, [CB[7]+K]) in the flow-through liquid + The CB[7] disappears because the content of CB[7] is extremely low. Collect the eluent and freeze dry to obtain a very small amount of high-purity solid CB[7] (>98.0%).

[0061] Comparative Example 1: A method for separating CB[5] and CB[7] using hybrid monolithic materials based on supramolecular affinity chromatography

[0062] The process and conditions were the same as in Example 1, except that the volume of tetramethoxysilane in the preparation system of the hybrid monolithic material in Example 1 was reduced to 0.5 mL, and the rest of the preparation and modification process and conditions (preparation of organic-inorganic hybrid monolithic material containing bipyridine) were the same as in Example 1. The obtained hybrid monolithic material containing bipyridine was named Monolith-Bp-3. The supramolecular affinity chromatography process and conditions (method for separating CB[5] and CB[7] based on supramolecular affinity chromatography) were the same as in Example 1.

[0063] Product characterization

[0064] Figure 13 This is a picture of Monolith-Bp-3. As can be seen from the picture, the material has an uneven texture, appears as a transparent gel, and lacks elasticity when pressed, indicating that the material does not have a rigid structure.

[0065] Product Application

[0066] Monolith-Bp-3 was used to selectively separate CB[5] and CB[7]. The separation of samples and detection methods were the same as in Example 1.

[0067] Evaluation results

[0068] Figure 14 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-3 in Comparative Example 1 shows a high CB[5] signal peak 2 (853 Da, [CB[5]+Na]). + Furthermore, a distinct signal peak of CB[7] (1185 Da, [CB[7]+Na]) can be observed. + Compared with Example 1, the content of CB[7] in the flow-through liquid increased significantly. This is because the material preparation was unsuccessful and the guest could not be successfully modified. The flow-through liquid was collected, and freeze-drying could not yield high-purity solid CB[5].

[0069] Figure 15 The MALDI-TOF MS spectrum of the eluent of Monolith-Bp-3 in Comparative Example 1 shows that no CB[7] signal peak was observed. This is because the material preparation was unsuccessful and the guest could not be successfully modified. The eluent was collected and lyophilized, but high-purity solid CB[7] could not be obtained.

[0070] Comparative Example 2: A method for separating CB[5] and CB[7] using hybrid monolithic materials based on supramolecular affinity chromatography

[0071] The process and conditions were the same as in Example 1, except that the volume of 3-chloropropyltrimethoxysilane in the preparation system of the hybrid monolithic material in Example 1 was reduced to 0.05 mL, and the remaining preparation and modification processes and conditions (preparation of organic-inorganic hybrid monolithic material containing bipyridine) were the same as in Example 1. The obtained hybrid monolithic material containing bipyridine was named Monolith-Bp-4. The supramolecular affinity chromatography process and conditions (method for separating CB[5] and CB[7] based on supramolecular affinity chromatography) were the same as in Example 1.

[0072] Product characterization

[0073] Figure 16 This is a picture of Monolith-Bp-4. As can be seen from the picture, the material has a slightly uneven overall texture, presenting a relatively transparent gel state. It exhibits low elasticity when pressed, indicating that the material does not possess a very rigid structure.

[0074] Product Application

[0075] Monolith-Bp-4 was used to selectively separate CB[5] and CB[7]. The separation of samples and detection methods were the same as in Example 1.

[0076] Evaluation results

[0077] Figure 17 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-4 in Comparative Example 2 shows a high CB[5] signal peak 2 (853 Da, [CB[5]+Na]). + Furthermore, a distinct signal peak of CB[7] (1185 Da, [CB[7]+Na]) can be observed. + Compared with Example 1, the content of CB[7] in the flow-through liquid increased significantly. This is because the material preparation was unsuccessful and the guest could not be successfully modified. The flow-through liquid was collected, and freeze-drying could not yield high-purity solid CB[5].

[0078] Figure 18 The MALDI-TOF MS spectrum of the eluent of Monolith-Bp-4 in Comparative Example 2 shows that no CB[7] signal peak was observed. This is because the material preparation was unsuccessful and the guest could not be successfully modified. The eluent was collected and lyophilized, but high-purity solid CB[7] could not be obtained.

[0079] Comparative Example 3: A method for separating CB[5] and CB[7] using hybrid monolithic materials based on supramolecular affinity chromatography

[0080] The preparation and modification process and conditions (preparation of the organic-inorganic hybrid monolithic material containing bipyridine) were the same as in Example 1, and the resulting hybrid monolithic material containing bipyridine was named Monolith-Bp-1. The supramolecular affinity chromatography method differed from that in that the loading conditions of the example were increased to 20 mL for the crude product solution volume, while the remaining processes and methods (methods for separating CB[5] and CB[7] based on supramolecular affinity chromatography) were the same as in Example 1.

[0081] Product characterization

[0082] Figure 19 This is a picture of Monolith-Bp-1. The picture shows that the material has a uniform texture, is a white, opaque solid, and exhibits some elasticity when pressed, indicating that it has a certain degree of rigidity.

[0083] Product Application

[0084] Monolith-Bp-1 was used to selectively separate CB[5] and CB[7]. The separation of samples and detection methods were the same as in Example 1.

[0085] Evaluation results

[0086] Figure 20 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-Bp-1 in Comparative Example 3 shows a high CB[5] signal peak 2 (853 Da, [CB[5]+Na]). + Furthermore, a distinct signal peak of CB[7] (1185 Da, [CB[7]+Na]) can be observed. + Compared with Example 1, the content of CB[7] in the flow-through liquid was significantly increased. This is because the excessive loading volume led to the enrichment and loading of the material. The flow-through liquid was collected, and lyophilization could not yield high-purity solid CB[5].

[0087] Figure 21 The MALDI-TOF MS spectrum of the eluent of Monolith-Bp-1 in Comparative Example 3 shows a clear CB[7] signal peak (1298 Da, [CB[7]+DHB-OH]). + Furthermore, a CB[5] signal peak 2 (853 Da, [CB[5]+Na]) was observed. + Compared with Example 1, the content of CB[5] in the eluent increased significantly. This is because the excessive loading volume led to the enrichment of the material. The eluent was collected, and high-purity solid CB[7] could not be collected by lyophilization.

[0088] Comparative Example 4: A method for separating CB[5] and CB[7] using hybrid monolithic materials based on supramolecular affinity chromatography

[0089] First, 1 mL of a 0.05 mol / L acetic acid aqueous solution was measured into a centrifuge tube. Then, 100 mg of polyethylene glycol-10000 was weighed into the same centrifuge tube and dissolved by sonication. Next, 0.5 mL of tetramethoxysilane solution and 0.2 mL of vinyltrimethoxysilane solution were measured into the same centrifuge tube and hydrolyzed for 1 h under ice bath conditions (-5 ℃). Then, 30 mg of 1,1′-bis(4-vinylbenzyl)-4,4′-bipyridine hydrochloride organic functional monomer and 3.0 mg of azobisisobutyronitrile were weighed into the same centrifuge tube and dissolved by sonication under ice bath conditions (-5 ℃). The reaction was carried out in a water bath in two steps at 40 ℃ for 15 h and 60 ℃ for 15 h. After the reaction was completed, the mixture was washed with deionized water to obtain an organic-inorganic hybrid monolithic column containing bipyridine, named Monolith-BVBp-1. The procedures and conditions for supramolecular affinity chromatography (the method for separating CB[5] and CB[7] based on supramolecular affinity chromatography) are the same as in Example 1.

[0090] Product characterization

[0091] Figure 22 This is a picture of Monolith-BVBp-1. The picture shows that the material has a uniform texture, is a white, opaque solid, and exhibits some elasticity when pressed, indicating that it has a certain degree of rigidity.

[0092] Product Application

[0093] Monolith-BVBp-1 was used to selectively separate CB[5] and CB[7]. The separation of samples and detection methods were the same as in Example 1.

[0094] Evaluation results

[0095] Figure 23 The MALDI-TOF MS spectrum of the flow-through liquid of Monolith-BVBp-1 in Comparative Example 4 shows a high CB[5] signal peak 2 (853 Da, [CB[5]+Na]). + Furthermore, a distinct signal peak of CB[7] (1185 Da, [CB[7]+Na]) can be observed. + Compared with Example 1, the content of CB[7] in the flow-through liquid was significantly increased. This may be because when the bipyridine moiety, as a guest component, crosslinks inside the polymer chain during the material synthesis process, both ends are capped. Due to the steric hindrance effect, the binding ability of CB[7] with bipyridine is weakened, making it difficult to selectively separate CB[5]. The flow-through liquid was collected, and lyophilization could not yield high-purity solid CB[5].

[0096] Figure 24 The MALDI-TOF MS spectrum of the eluent of Monolith-BVBp-1 in Comparative Example 4 shows that no obvious CB[7] signal was observed in the figure, which may be because the adsorption capacity of the material for CB[7] decreased. The eluent was collected, and lyophilization could not yield high-purity solid CB[7].

Claims

1. A method for preparing an organic-inorganic hybrid monolithic material containing bipyridine, characterized in that: Using tetramethoxysilane and 3-chloropropyltrimethoxysilane as silane reagents, and urea and polyethylene glycol-10000 as porogens, the silane reagents were hydrolyzed and then co-condensed to form a monolithic silica material containing chlorine atoms. Then, 4,4-bipyridine was modified by electrophilic substitution reaction to obtain an organic-inorganic hybrid monolithic material containing bipyridine.

2. The preparation method according to claim 1, characterized in that: You can follow these steps: First, measure 3-8 mL (preferably 4-7 mL; more preferably 5-6 mL) of acetic acid solution with a concentration of 0.001-0.1 mol / L (preferably 0.005-0.05 mol / L; more preferably 0.01-0.03 mol / L) into a container. Weigh 300-900 mg (preferably 400-800 mg; more preferably 500-600 mg) of urea and 200-600 mg (preferably 300-500 mg; more preferably 400-450 mg) of polyethylene glycol-10000 into the same container and mix to dissolve. Then, measure 1-3 mL (preferably 1.2-2.8 mL; more preferably 1.5-2 mL) of tetramethoxysilane and 0.1-1 mL (preferably 0.3-0.8 mL; more preferably 0.5-0.7 mL) of [unspecified ingredient]. 3-Chloropropyltrimethoxysilane (mL) was hydrolyzed in the above-mentioned container under ice bath conditions (-10~0 °C) for 3~6 h, and then reacted in a water bath at 30~90 °C (preferably: 40~80 °C; more preferably: 50~70 °C) for 12~20 h. Finally, the pore-forming agent was washed away with an ethanol aqueous solution with a volume concentration of 10~90% (preferably: 30~70%; more preferably: 40~60%), and dried to obtain a monolithic silica gel material with chlorine atoms. 300~600 mg (preferably: 400~500 mg; more preferably: 420~480 mg) of 4,4-bipyridine was dissolved in 10~20 mL of acetonitrile solution, and 200~500 mg (preferably: 300~400 mg; more preferably: 320~380 mg) of the above-mentioned monolithic silica gel material with chlorine atoms was added, and reacted at 50~100 °C for 12~20 h. h, and finally washed with an aqueous ethanol solution of 10-90% (preferably 30-70%; more preferably 40-60%), and dried to obtain an organic-inorganic hybrid monolithic material containing bipyridine.

3. The preparation method according to claim 2, characterized in that: After washing away the pore-forming agent, the silica gel monolithic material containing chlorine atoms is obtained by vacuum drying at 60~80 ℃; After washing with ethanol, the material was vacuum dried at 60-80 °C to obtain an organic-inorganic hybrid monolithic material containing bipyridine.

4. An organic-inorganic hybrid monolithic material containing bipyridine prepared by the method of claim 1, 2 or 3.

5. A method for separating CB[5] and CB[7] based on supramolecular affinity chromatography, characterized in that: Using an organic-inorganic hybrid monolithic material containing bipyridine as an adsorbent, the selective separation of CB[5] and CB[7] from the crude product obtained after synthesis and crude separation of glycourea and paraformaldehyde is achieved by taking advantage of the difference in host-guest interaction between CB[5] and CB[7] and the bipyridine functional group.

6. The method according to claim 5, characterized in that: You can follow these steps: ① Weigh 50-100 mg of the organic-inorganic hybrid monolithic material containing bipyridine as described in claim 3 into a centrifuge tube; ② Equilibrate: Measure 2-4 mL of 30-70% (preferably 40-60%; more preferably 45-55%) acetonitrile aqueous solution into a centrifuge tube, shake (200-400 rpm) for 30-60 min, centrifuge to remove the supernatant, repeat the operation 2-5 times; ③ Load the sample: Measure 2-10 mL (preferably 3-9 mL; more preferably 4-6 mL) of a crude product solution containing CB[5] and CB[7] (obtained by synthesis and crude separation of glycyrrhizin and paraformaldehyde, in which incompletely separated CB[6] and byproducts still remain; dissolved in 20-200 mmol / L ammonium acetate solution, with a concentration of 1-3 mg / mL) into the above centrifuge tube, shake (200-400 rpm) for 12-20 min. After h, centrifuge to collect the flow-through containing CB[5]; ④ Washing: Measure 2~10 mL of 20~200 mmol / L (preferably: 50~150 mmol / L; more preferably: 70~120 mmol / L) ammonium acetate solution (dissolved in 30~70% methanol aqueous solution by volume) into the above centrifuge tube, shake (200~400 rpm) for 30~60 min, and centrifuge to remove the wash solution containing impurities such as CB[6] (residual in the crude separation process), and repeat the washing operation 3 times; ⑤ Elution: Measure 2~10 mL of 1~2 M (preferably: 1~1.5 M, more preferably: 1~1.2 M) ammonium acetate aqueous solution into the above centrifuge tube, shake (200~400 rpm) for 30~60 min. After centrifugation for min, the eluent of CB[7] was collected. The elution operation was repeated 2 to 5 times to obtain the eluent. The flow-through liquid and the eluent were collected separately and combined. After drying, solid samples of CB[5] and CB[7] were obtained.

7. An organic-inorganic hybrid monolithic material containing bipyridine as described in claim 4 can be used as a supramolecular affinity chromatography packing material for selectively separating CB[5] and CB[7] from the crude product (which still contains incompletely removed CB[6] and byproducts) obtained after synthesis and crude separation of glycourea and paraformaldehyde.

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