A cationic molecular cage, its preparation method and application

Abstract

This disclosure provides a cationic molecular cage, its preparation method, and its application. The structural formula of the cationic molecular cage is shown in formula (I), where X represents a coordinating anion selected from PF6. ‑ AsF6 ‑ Cl ‑ ,Br ‑ I ‑ CF3COO ‑ SO4 2‑ At least one of the following, with a total anionic charge of 8. This pyridine cationic molecular cage can form multiple C-H…O / N-H…O hydrogen bonds with sugar molecules through cationically polarized pyridine ring C-H, urea, and thiourea functional groups, and the two parallel aromatic planes form hydrophobic / CH-π interactions with the vertical C-H bonds in the sugar chair conformation; at the same time, there may be mechanisms such as complementary host-guest spatial structures, complementary charges, and chiral matching in the recognition system between the molecular cage and the sugar molecule, thereby enabling selective recognition of sugar substrates in the aqueous phase.

Description

Technical Field

[0001] This invention relates to the field of organic biomaterials technology, specifically to a cationic molecular cage, its preparation method, and its application. Background Technology

[0002] Molecular recognition is fundamental to the physiological functions of bioactive substances and is an important area of ​​research in supramolecular chemistry. Specific recognition by sugar-protein receptors plays a crucial role in many physiological and pathological processes, including cell communication, sperm-egg recognition, viral adhesion, and tumor metastasis. Highly glycosylated viruses such as coronaviruses, retroviruses (HIV and hepatitis B), and orthomyxoviruses (influenza AC) typically adhere to host cells via sugar-protein specific recognition through oligosaccharide chains exposed on their envelope surfaces. Utilizing sugar recognition receptors to specifically bind to these sugar substrates can inhibit viral-cell interactions, thereby preventing viral invasion and infection. However, natural sugar recognition receptors suffer from drawbacks such as difficulty in preparation, high cost, and poor stability; therefore, the development of artificial sugar recognition receptors is urgently needed.

[0003] Currently, the design of artificial receptors for sugar recognition in aqueous phases is mainly based on two strategies—boronic acid receptors and non-boronic acid receptors. Boronic acid receptors utilize the covalent interaction between the boronic acid group and compounds containing cis-1,2- or 1,3-diol structures, with the boron atom in a trivalent planar sp... 2 (Neutral) to tetravalent tetrahedron sp 3 The rapid interconversion of (anions) to form reversible five / six-membered cyclic esters is an enthalpy-driven process. Compared to carbohydrate substrates, boric acids generally tend to bind to polyols and are pH-sensitive. Non-boronic acid receptors mainly include macrocyclic systems (cyclodextrins, porphyrins, cucurbiturils, and calixarenes, etc.), linear systems (gel polysaccharides, conjugated aromatic rings, and polypeptides, etc.), branched systems, and molecular cage systems. Non-boronic acid receptors recognize sugars through non-covalent interactions such as hydrogen bonding, CH-π interactions, electrostatic interactions, hydrophobic interactions, and van der Waals forces, mimicking the specific recognition of sugar molecules by natural sugar receptors such as bacterial periplasmic proteins and lectins. This represents a cutting-edge area of ​​research in glycochemistry and supramolecular chemistry.

[0004] In recent years, researchers have successfully developed a series of biomimetic sugar recognition receptors in aqueous phases based on biomimetic principles. Mazik et al. reported a branched sugar recognition receptor based on charge-enhanced hydrogen bond interactions. The selectivity and binding strength of this receptor to sugars need further improvement before practical application. Yoshiza et al. reported a sucrose recognition receptor based on multiple CH-π interactions. This receptor forms a 1:1 complex with sucrose, which is spatially complementary, representing a unique design for sugar recognition receptors, applicable only to sucrose as a specific substrate. Francesconi and Roelens et al. reported a methyl-α-L-fucoside recognition receptor based on five NH…O hydrogen bonds and hydrophobic / CH-π synergistic interactions. Recently, they also utilized a portion of the macrocycle structure to achieve selective recognition of methyl-β-DN,N'-diacetylchitoside (MeβGlcNAc2). Molecular model calculations indicate that hydrogen bonding and CH-π interactions between the sugar NAc functional group and the receptor carbazole are the source of the receptor's selectivity for MeβGlcNAc2. However, these receptors exhibit weak binding strength when binding to non-derived monosaccharides and disaccharides, such as glucose, which has significant biological and clinical importance. Inspired by the specific recognition of sugar molecules by lectins, Davis et al. synthesized a series of molecular cage receptors capable of recognizing sugars in aqueous solutions. Most of these receptors show strong binding to oligosaccharides / polysaccharides or β-N-acetyl-D-glucosamine, but low affinity for monosaccharides. Recently, Davis's group synthesized a glucose biomimetic receptor by replacing the previous amide functional group with a urea functional group. This receptor provides a cavity that matches glucose, exhibiting high selectivity and strong binding to glucose. The drawbacks are that each molecule requires the introduction of twenty-seven carboxyl functional groups, resulting in a complex molecular structure that hinders in-depth research into the recognition mechanism; the preparation process is cumbersome, and the synthetic yield is low.

[0005] In summary, although some progress has been made in the construction of biomimetic sugar recognition receptors in aqueous phase in recent years, there are still very few biomimetic sugar recognition receptors with high recognition selectivity and high binding strength, and they face challenges such as complicated preparation, small recognition range and unclear recognition rules. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a cationic molecular cage, its preparation method and application.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a cationic molecular cage is provided, the structural formula of which is shown in formula (I):

[0008]

[0009] In formula (I), X represents a coordinating anion, and X is selected from PF6. - AsF6- Cl - ,Br - I - CF3COO - SO4 2- At least one of them, the total anion charge is 8.

[0010] This disclosure presents a pyridine cationic molecular cage as an artificial receptor for sugar recognition. The pyridine cationic molecular cage can form multiple CH…O / NH…O hydrogen bonds with sugar molecules through cationically polarized pyridine ring CH, urea and thiourea functional groups, and the two parallel aromatic planes form hydrophobic / CH-π interactions with the vertical CH bonds in the sugar chair conformation. At the same time, the recognition system between the molecular cage and the sugar molecule may have mechanisms such as complementary host-guest spatial structures, complementary charges and chiral matching, thereby enabling selective recognition of sugar substrates in the aqueous phase.

[0011] On the other hand, a method for preparing the aforementioned cationic molecular cage is provided, comprising the following steps:

[0012] S1: After adding dibenzyl bromide and tetrapyridinium pyrene to a solvent and mixing them, the reaction was carried out. After filtering and washing the product obtained from the reaction, hexafluorophosphate was added to precipitate the product, which yielded the intermediate PBP-HS.

[0013] S2: After adding intermediate PBP-HS, tetrapyridine biphenyl and catalyst to solvent and mixing, the mixture is heated under reflux. After the reaction is complete, a coordinating anion salt is added for ion exchange reaction. The precipitate obtained by separating the product from the ion exchange reaction is the cationic molecular cage.

[0014] This disclosure discloses a method for constructing sugar recognition receptors based on pyridine cationic organic molecular cages. This avoids the need for additional water-soluble groups in the preparation process, thus solving the problems of cumbersome preparation and low yield of sugar recognition receptors. The method for preparing the cationic molecular cages disclosed herein requires no template and can synthesize two cationic molecular cage compounds in two steps. Furthermore, water-soluble molecular cage compounds with different coordinating ions can be obtained by adjusting the coordinating ions of the molecular cages.

[0015] Specifically, the preparation method of the intermediate PBP-HS is as follows:

[0016] After adding dibenzyl bromide and tetrapyridine pyrene to a solvent and mixing them, the reaction was carried out. After the reaction was completed, dichloromethane was added to precipitate product 1. After filtering and washing, the solid 1 obtained was dissolved and excess hexafluorophosphate was added to precipitate product. After filtering, washing and drying, the intermediate PBP-HS was obtained.

[0017] Specifically, the steps in step S2 are as follows:

[0018] After adding intermediate PBP-HS, tetrapyridine biphenyl and catalyst to solvent and mixing, the mixture was heated under reflux. After the reaction was completed, excess tetrabutylammonium chloride was added to precipitate product 3. After centrifugation and washing, solid 2 was dissolved and trifluoroacetic acid (TFA) and diatomaceous earth were added. The mixture was then distilled under reduced pressure. Solid 4 was separated by column chromatography to obtain cationic molecular cages.

[0019] Furthermore, the mobile phase for column chromatography consisted of acetonitrile and water containing 0.1% TFA; the column was a C18 reversed-phase column.

[0020] In one embodiment, the molar ratio of p-dibenzyl bromide to tetrapyridine pyrene is (1000:1) to (4:1); for example, it can be selected from, but is not limited to, 1000:1, 950:1, 900:1, 850:1, 800:1, 750:1, 700:1, 650:1, 600:1, 550:1, 500:1, 450:1, 400:1, 350:1, 300:1, 250:1, 200:1, 150:1, 100:1, 50:1, 40:1, 30:1, 20:1, 10:1, 5:1, 1:1, 1:3, 1:4; preferably (1:800) to (1:4), more preferably (1:650) to (1:4), and even more preferably (1:400) to (1:4).

[0021] In one embodiment, the molar ratio of PBP-HS to p-tetrapyridinepyrene is (1:100) to (100:1); for example, it can be selected from, but is not limited to, 100:1, 90:1, 80:1, 70:1, 60:1, 50:1, 40:1, 30:1, 20:1, 10:1, 5:1, 1:1, 1:5, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100; preferably (1:85) to (85:1), more preferably (1:55) to (55:1), and even more preferably (1:35) to (35:1).

[0022] In this disclosure, the molar ratio of p-dibenzyl bromide to tetrapyridinium pyrene, and the molar ratio of PBP-HS to p-dibenzyl bromide, are among the key factors affecting the yield of cationic molecular cages and the reaction time. If the molar ratio of p-dibenzyl bromide to tetrapyridinium pyrene is too low, it will affect the purity and yield of PBP-HS and lead to a prolonged reaction time. If the molar ratio of PBP-HS to p-dibenzyl bromide is too high or too low, it will affect the yield of molecular cages, leading to the formation of a large amount of polymer and preventing the formation of macrocyclic compounds.

[0023] In one embodiment, the reaction temperature in step S1 is 0–150°C and the time is 0.1–10000 h; and / or, the temperature of the reflux reaction in step S2 is 0–150°C and the time is 0.1–10000 h.

[0024] In this disclosure, the reaction temperature in step S1 is 0–150°C, and the reaction time is 0.1–10000 h; for example, the reaction temperature can be, but is not limited to, 0°C, 15°C, 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C; the reaction time can be, but is not limited to, 0.1 h, 1 h, 5 h, 10 h, 24 h, 48 h, 72 h, 96 h, 120 h, 150 h, 200 h, 300 h, 400 h, or 500 h. h, 600h, 700h, 800h, 900h, 1000h, 2000h, 3000h, 4000h, 5000h, 6000h, 7000h, 8000h, 9000h, 10000h; preferably, the reaction temperature in step S1 is 40-120℃ and the reaction time is 24-8000h; more preferably, the reaction temperature in step S1 is 40-100℃ and the reaction time is 72-5000h; more preferably, the reaction temperature in step S1 is 40-80℃ and the reaction time is 72-4000h.

[0025] In this disclosure, the temperature of the reflux reaction in step S2 is 0–150°C, and the time is 0.1–10000 h; for example, the reaction temperature can be, but is not limited to, 0°C, 15°C, 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C; the reaction time can be, but is not limited to, 0.1 h, 1 h, 5 h, 10 h, 24 h, 48 h, 72 h, 96 h, 120 h, 150 h, 200 h, 300 h, or 400 h. 500h, 600h, 700h, 800h, 900h, 1000h, 2000h, 3000h, 4000h, 5000h, 6000h, 7000h, 8000h, 9000h, 10000h; preferably, the reaction temperature in step S1 is 40-120℃ and the reaction time is 24-8000h; more preferably, the reaction temperature in step S1 is 40-100℃ and the reaction time is 72-5000h; more preferably, the reaction temperature in step S1 is 40-80℃ and the reaction time is 72-4000h.

[0026] This disclosure adjusts the reaction rate of the cation molecular cage by adjusting the temperature and time of the reaction in step S1 and the temperature and time of the heating reflux reaction in step S2.

[0027] In one embodiment, the solvents in steps S1 and S2 are each independently selected from at least one of acetonitrile, dichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, dioxane, ethanol, methanol, tetrahydrofuran, mesitylene, and chloroform.

[0028] In one embodiment, the catalyst is tetrabutylammonium iodide.

[0029] On the other hand, the application of the aforementioned cationic molecular cage in recognizing sugars in aqueous solutions is provided.

[0030] In one embodiment, the cationic molecular cage binds sugar in an aqueous solution at a binding temperature of 4-100°C for a binding time of 0.1-2400 min.

[0031] In one embodiment, the aqueous solution is at least one of PBS buffer, human serum, and cell growth medium; the sugar is at least one of monosaccharide, oligosaccharide, and polysaccharide.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The sugar recognition molecular cages reported in the literature (J.Am.Chem.Soc.2021,143,15688-15700) are more inclined to recognize glucose and glucose derivatives in aqueous phase, and have almost no recognition ability for disaccharides. Single crystal diffraction experiments show that the cationic molecular cage disclosed in this invention has a cavity size suitable for binding with sugar molecules. The cationic molecular cage disclosed in this invention has a larger cavity opening than the sugar recognition molecular cages reported in the literature (J.Am.Chem.Soc.2021,143,15688-15700). The cationic molecular cage disclosed in this invention can achieve good recognition performance for disaccharide molecules in aqueous phase, indicating that the cationic molecular cage disclosed in this invention has a wider recognition range and better recognition ability.

[0034] (2) Compared with the preparation method of sugar recognition molecular cage reported in the literature (J.Am.Chem.Soc.2021,143,15688-15700), the preparation method of cationic molecular cage disclosed in this paper has a shorter preparation time, higher yield, and does not use a reaction template, resulting in better reaction atom economy. Attached Figure Description

[0035] Figure 1 The 1H NMR spectrum of the intermediate PBP-HS;

[0036] Figure 2 The carbon NMR spectrum of the intermediate PBP-HS;

[0037] Figure 3For PBP-1 . 8CF3COO and PBP-2 . High-resolution mass spectra of the two molecular cages of 8CF3COO;

[0038] Figure 4 The 1H NMR spectrum of the PBP-1.8Cl molecular cage;

[0039] Figure 5 The 1H NMR spectrum of the PBP-1.8Cl molecular cage;

[0040] Figure 6 The single-crystal structure diagram of PBP-1.8AsF6 is shown.

[0041] Figure 7 For different concentrations of glucose and PBP-1.8Cl molecular cages 1 1H NMR titration analysis spectrum;

[0042] Figure 8 The figure shows the fitting curve of the binding constant when PBP-1.8Cl molecular cages and glucose are bound together in an aqueous phase at a 1:1 ratio.

[0043] Figure 9 For different concentrations of galactose and PBP-1.8Cl molecular cages 1 1H NMR titration analysis spectrum;

[0044] Figure 10 The figure shows the fitting curve of the binding constant when PBP-1.8Cl molecular cages and galactose are bound together in an aqueous phase at a 1:1 ratio. Detailed Implementation

[0045] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this invention are commonly used reagents and instruments.

[0046] Example 1

[0047] This embodiment provides a cationic molecular cage and its preparation method. The structural formula of the cationic molecular cage and its preparation method are as follows:

[0048] Preparation of intermediate PBP-HS:

[0049] 21.0 g of p-dibenzyl bromide (80 mmol) and 510 mg (1 mmol) of tetrapyridine pyrene (TPP) were dissolved in 500 mL of anhydrous N,N-dimethylformamide (DMF), and the mixture was stirred at 50 °C for 7 days. After cooling to room temperature, 1 L of dichloromethane was added, and a solid precipitated. The solid was obtained by filtration under reduced pressure and washed three times with acetonitrile. The solid was dissolved in 30 mL of water, and excess NH4PF6 was added, resulting in the precipitation of a solid. The solid was then filtered under reduced pressure, washed three times with water, and freeze-dried to obtain 1.64 g of a white solid, which was the intermediate PBP-HS. The yield of intermediate PBP-HS was calculated to be 90%. The 1H NMR spectrum of intermediate PBP-HS is shown below. Figure 1 As shown, the carbon NMR spectrum is as follows: Figure 2 As shown, by Figure 1 and Figure 2 It can be seen that the intermediate PBP-HS was successfully synthesized.

[0050] Preparation of cation molecular cages:

[0051] 100 mL of anhydrous acetonitrile was added to a round-bottom flask containing 183 mg (0.1 mmol) PBP-HS, 46.2 mg tetrapyridine biphenyl (0.1 mmol) (TBP), and 7.4 mg (0.02 mmol) tetrabutylammonium iodide (TBAI). The reaction mixture was stirred and refluxed for 3 days. After cooling to room temperature, excess tetrabutylammonium chloride (TBACl) was added, and a solid precipitated. The solid was collected by centrifugation and washed three times with water. The solid was dissolved in 20 mL of methanol (MeOH), and 2 mL of trifluoroacetic acid (TFA) and 2 g of diatomaceous earth were added. The mixture was then subjected to rotary distillation under reduced pressure. The evaporated sample was loaded onto a dry column using an automated column chromatography system with C24-245 ppm. 18 The product was separated by a reverse-phase column elution with a gradient of acetonitrile and water containing 0.1% TFA, yielding two molecular cages, PBP-1 and PBP-2. The high-resolution mass spectra of the obtained products are shown below. Figure 3 As shown, from Figure 3 From this, we can see that the mass-to-charge ratio of 1033.2647 is [PBP-1]. . 6CF3COO] 2+ and [PBP-2] . 6CF3COO] 2+ The ion peaks confirm that PBP-1 . 8CF3COO and PBP-2 . Successful synthesis of 8CF3COO molecular cage.

[0052] The PBP-1 molecular cage was concentrated to 30 mL, and excess ammonium hexafluorophosphate (NH4PF6) was added. The precipitated solid was filtered under reduced pressure, the filter cake sample was washed three times with water, and then freeze-dried to obtain PBP-1. . 8PF6 (48.4mg), calculated, PBP-1. The yield of 8PF6 was 19%;

[0053] The PBP-2 molecular cage was concentrated to 30 mL, and excess ammonium hexafluorophosphate (NH4PF6) was added. The precipitated solid was filtered under reduced pressure, the filter cake sample was washed three times with water, and then freeze-dried to obtain PBP-2. . 8PF6 (48.4mg), calculated, PBP-1 . The yield of 8PF6 was 10%.

[0054] 12.8mg PBP-1 . 8PF6 was dissolved in 10 mL of acetonitrile, and 200 mg of TBACl was added. The precipitated solid was filtered under reduced pressure, washed three times with acetonitrile, and dried under vacuum to obtain molecular cage PBP-1. . 8Cl, yield 99%. The product was characterized by 1H NMR spectroscopy as follows: Figure 4 As shown, PBP-1 has been proven. . Successful synthesis of 8Cl.

[0055] 12.8mg PBP-2 . 8PF6 was dissolved in 10 mL of acetonitrile, and 200 mg of TBACl was added. The precipitated solid was filtered under reduced pressure, washed three times with acetonitrile, and dried under vacuum to obtain molecular cage PBP-2. . 8Cl, yield 99%. The product was characterized by 1H NMR spectroscopy as follows: Figure 5 As shown, PBP-2 has been proven. . Successful synthesis of 8Cl.

[0056] 12.8mg PBP-1 . 8PF6 was dissolved in 10 mL of acetonitrile, and 200 mg of Na2SO4 was added. The precipitated solid was filtered under reduced pressure, washed three times with acetonitrile, and dried under vacuum to obtain molecular cage PBP-1. . 8SO4, yield 99%.

[0057] 12.8mg PBP-2 . 8PF6 was dissolved in 10 mL of acetonitrile, and 200 mg of Na2SO4 was added. The precipitated solid was filtered under reduced pressure, washed three times with acetonitrile, and dried under vacuum to obtain molecular cage PBP-2. . 8SO4, yield 99%.

[0058] 8.3mg PBP-1 . 8Cl was dissolved in 10 mL of water, and 200 mg of NaAsF6 was added. The precipitated solid was filtered under reduced pressure, washed three times with water, and dried under vacuum to obtain molecular cage PBP-1. . 8AsF6, yield 99%, PBP-1 .The single crystal structure diagram of 8AsF6 is shown below. Figure 6 As shown, from Figure 6 It can be seen that PBP-1 . 8AsF6 has cavities that bind to sugar molecules.

[0059] 8.3mg PBP-2 . 8Cl was dissolved in 10 mL of water, and 200 mg of NaAsF6 was added. The precipitated solid was filtered under reduced pressure, washed three times with water, and dried under vacuum to obtain molecular cage PBP-2. . 8AsF6, yield 99%.

[0060] In this embodiment, PBP-1 . 8Cl and PBP-2 . The synthetic route for the 8Cl cation molecular cage is as follows:

[0061]

[0062] Example 2

[0063] Example 2 verifies the recognition performance of the cationic molecular cage obtained in Example 1 for carbohydrate compounds in the aqueous phase.

[0064] This embodiment uses nuclear magnetic resonance titration of hydrogen spectrum ( 1 The binding constants of cationic molecular cages and different sugar molecules in aqueous phase were determined by using ¹H NMR titration to determine the recognition performance of cationic molecular cages for sugar compounds in aqueous phase. The specific experimental steps are as follows:

[0065] Prepare 500 μL of 0.1 mmol / L PBP-1 containing 10 mM PBS buffer in the NMR tube. . 8Cl or PBP-2 . The 1H NMR spectra of PBP-1.8Cl and PBP-2.8Cl molecular cages were measured at 25℃ using aqueous solutions of 8Cl molecular cages. Then, high-concentration deuterated aqueous solutions of sugar molecules with different equivalent numbers were gradually added to the solution. The concentration of the original deuterated aqueous solution of sugar molecules varied depending on the solubility of different sugar molecules, aiming to maximize the sugar concentration while minimizing the added volume. For example, a 500 mmol / L original deuterated aqueous solution was prepared and added in batches, resulting in a total equivalent number of glucose molecules in the NMR tube solution that was 0, 10, 20, 50, 100, 200, 300, 400, 500, 750, and 1000 times the molar number of PBP molecular cages. After addition, the solution was shaken well, and the 1H NMR spectra were measured. The binding constant Ka was obtained by nonlinear fitting of a 1:1 host-guest binding model according to the following formula:

[0066]

[0067] In the formula, [H] is the total concentration of PBP molecular cages; [G] is the total concentration of sugar molecules; L is the maximum value of Δδ; and Δδ is the chemical shift change of a specific peak in the molecular cage.

[0068] PBP-1 can be obtained using OriginPro software. . The binding constant of 8Cl and glucose molecules in the aqueous phase is Ka = 77 mol. -1 The titration spectrum is as follows: Figure 7 As shown, the fitted curve and the fitting constant are as follows: Figure 8 As shown.

[0069] Similarly, PBP-1 can be obtained using OriginPro software. . The binding constant Ka of 8Cl and galactose molecules in the aqueous phase is 41 mol. -1 The titration spectrum is as follows: Figure 9 As shown, the fitted curve and the fitting constant are as follows: Figure 10 As shown.

[0070] PBP-1 can be measured using the same method. . 8Cl and PBP-2 . The binding constants of 8Cl with different sugar molecules in an aqueous phase at a 1:1 ratio are shown in Table 1.

[0071] Table 1

[0072]

[0073] As can be seen from Table 1, the cationic molecular cages of this disclosure have a better binding capacity for disaccharide molecules in the aqueous phase; and exhibit good selectivity between monosaccharide and disaccharide molecules.

[0074] Example 3

[0075] In Example 3, the same method as in Example 2 was used to determine the PBP-1. . 8CF3COO and PBP-2 . The binding constants of 8CF3COO with different sugar molecules in a 1:1 ratio in an aqueous phase were used to verify the recognition performance of the cationic molecular cage obtained in Example 1 for sugar compounds in an aqueous phase. The results are shown in Table 2.

[0076] Table 2

[0077]

[0078] As can be seen from Table 2, the cationic molecular cages of this disclosure have a better binding capacity for disaccharide molecules in the aqueous phase; and exhibit good selectivity between monosaccharide and disaccharide molecules.

[0079] Example 4

[0080] In Example 4, the same method as in Example 2 was used to determine the PBP-1. . 4SO2 and PBP-2 . The binding constants of 8SO2 with different sugar molecules in a 1:1 ratio in an aqueous phase were used to verify the recognition performance of the cationic molecular cages obtained in Example 1 for sugar compounds in an aqueous phase. The results are shown in Table 3.

[0081] Table 3

[0082]

[0083] As can be seen from Table 3, the cationic molecular cage of this disclosure has a better binding ability to disaccharide molecules in the aqueous phase; and has good selectivity between monosaccharide and disaccharide molecules.

[0084] Since PBP.8PF6 and PBP.8AsF6 are insoluble in water, their selective recognition of sugars in the aqueous phase could not be studied. However, they have good crystallinity, and by culturing and determining the single-crystal structure of PBP-1.8AsF6, the mechanism of molecular cage recognition of sugars was further understood.

[0085] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A cationic molecular cage, characterized in that, The structural formula of the cationic molecular cage is shown in formula (I): Formula (I) In formula (I), X represents a coordinating anion, and X is selected from Cl. - ,Br - I - CF3COO - SO4 2- At least one of them, the total anion charge is 8.

2. The method for preparing a cationic molecular cage as described in claim 1, characterized in that, Includes the following steps: S1: After adding dibenzyl bromide and tetrapyridinium pyrene to a solvent and mixing them, the reaction was carried out. After filtering and washing the product obtained from the reaction, hexafluorophosphate was added to precipitate the product, which yielded the intermediate PBP-HS. S2: After adding intermediate PBP-HS, tetrapyridine biphenyl and catalyst to solvent and mixing, the mixture is heated under reflux. After the reaction is complete, a coordinating anion salt is added for ion exchange reaction. The precipitate obtained by separating the product from the ion exchange reaction is the cationic molecular cage.

3. The preparation method according to claim 2, characterized in that, The molar ratio of p-dibenzyl bromide to tetrapyridine pyrene is (1:1000) to (1:4).

4. The preparation method according to claim 2, characterized in that, The molar ratio of PBP-HS and tetrapyridine biphenyl is (1:100) to (100:1).

5. The preparation method according to claim 2, characterized in that, The reaction temperature in step S1 is 0~150℃ and the time is 0.1~10000h; and / or, the temperature of the reflux reaction in step S2 is 0~150℃ and the time is 0.1~10000h.

6. The preparation method according to claim 2, characterized in that, The solvents used in steps S1 and S2 are each independently selected from at least one of acetonitrile, dichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, dioxane, ethanol, methanol, tetrahydrofuran, mesitylene, and chloroform.

7. The preparation method according to claim 2, characterized in that, The catalyst is tetrabutylammonium iodide.

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