Novel organic framework material based on alkali metal and alkaline earth metal ion pairs as well as preparation method and application of novel organic framework material

Abstract

The invention discloses a novel bridging organic framework material based on alkali metal and alkaline earth metal ion pairs and a preparation method and application thereof. Firstly, the invention provides a super-cyclic compound as shown in a formula I which is described in the specification. The super-cyclic compound I of the crown ether chain connected tetraoxacalix [2] arene [2] triazine skeleton provided by the invention is obtained by reacting a compound as shown in a formula II, a compound as shown in a formula III and cesium fluoride in an organic solvent. The synthesis method has the characteristics that the raw materials are cheap and easy to obtain, the operation is simple and convenient, the reaction is efficient, the reaction condition is mild, the product is stable and easy to separate in the air, and the product purity is high; and the ion pair bridging organic framework material constructed by the formula I can show good practicability and application prospects in adsorption of radioactive waste gases (including iodine steam but not limited to iodine steam, such as harmful gases such as xenon and krypton). # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the field of organic chemistry, and specifically relates to a novel organic framework material based on alkali metal and alkaline earth metal ion pairs, and a preparation method and application thereof. Background Art

[0002] Supramolecular chemistry plays an important role in many fields, and host-guest chemistry is an important branch of supramolecular chemistry. Ion pair recognition refers to the process in which a host molecule with both anion recognition sites and cation recognition sites in its molecular structure simultaneously binds to anions and cations to form a multi-component complex. Due to the simultaneous presence of anion and cation interaction sites, ion pair receptors exhibit greater advantages in recognition strength and selectivity compared to individual anion and cation receptors (Jonathan L. Sessler. Chem. Rev. 2019, 119, 9753-9835).

[0003] Effectively removing radioactive waste gases (such as iodine, xenon, and krypton) during nuclear reactor operation, fuel reprocessing, and nuclear accidents is crucial for the sustainable development of the nuclear industry and public health (Haefner, D.; Tranter, T. Report No. INL / EXT-07-12299, Idaho National Laboratory, 2007). Solid-phase adsorption is a viable method for removing radioactive waste gases in reprocessing plants. However, the adsorption capacity of currently developed adsorbents (such as activated carbon and metal-organic frameworks) is limited (Yaghi, OIChem. Rev. 2012, 112, 673–674; Wang, S. Chem. 2022, 8, 1442–1459). Therefore, finding more effective and economical adsorbents for removing radioactive waste gases is crucial. Summary of the Invention

[0004] An object of the present invention is to provide a super macrocyclic compound having a tetraoxacalix[2]arene[2]triazine skeleton connected by crown ether chains.

[0005] The present invention provides a super macrocyclic compound having a tetraoxacalix[2]arene[2]triazine skeleton connected by a crown ether chain, and its general structural formula is shown in Formula I:

[0006]

[0007] In the general structural formula of Formula I, R1 and R2 are selected from any one of the following groups:

[0008] R1=H; OH; OBn; F; Cl; Br; I; OMe; OEt; OPr; OBu;

[0009] R2=H; OH; OMe; OEt; OPr; Me; Et; Pr; F; Cl; Br; I;

[0010]

[0011] In the above groups, OBn represents a benzyloxy group, OMe represents a methoxy group, OEt represents an ethoxy group, OPr represents a propoxy group, and OBu represents a butoxy group.

[0012] Another object of the present invention is to provide a method for preparing the compound represented by the above formula I.

[0013] The method for preparing the compound represented by formula I provided by the present invention comprises the following steps:

[0014] Reacting the compound represented by formula II with the compound represented by formula III to obtain the compound represented by formula I;

[0015]

[0016] In the formula II and formula III, the definitions of R1 and R2 are the same as those in the aforementioned formula I, and R1 and R2 are selected from any one of the following groups:

[0017] R1=H; OH; OBn; F; Cl; Br; I; OMe; OEt; OPr; OBu;

[0018] R2=H; OH; OMe; OEt; OPr; Me; Et; Pr; F; Cl; Br; I;

[0019]

[0020] In addition, when R1 and R2 are selected from any one of the following, the method further comprises the step of deprotecting the benzyl group:

[0021] R1=OBn

[0022]

[0023] In the step of constructing the structure of formula I, the reaction is carried out in an organic solvent, and the organic solvent is selected from at least one of the following: acetonitrile, tetrahydrofuran, acetone, dichloromethane, and N,N-dimethylformamide, preferably acetonitrile.

[0024] The reaction is carried out under alkaline conditions, and the base is selected from at least one of the following: cesium fluoride, N,N-diisopropylethylamine, potassium carbonate, sodium carbonate, sodium hydroxide, and cesium carbonate, preferably cesium fluoride.

[0025] In the reaction, the compound represented by formula II, the compound represented by formula III, the base, and the organic solvent are used in a ratio of (1-5) mmol: (1-5) mmol: (8-40) mmol: (100-500) mL, respectively. In the reaction, the reaction temperature is 24-120° C., and the reaction time is 1-48 hours.

[0026] The compound represented by the above formula II as an intermediate for preparing the compound represented by formula I also falls within the scope of protection of the present invention.

[0027] The present invention also provides a method for preparing the compound represented by the above formula II.

[0028] The compound represented by formula II is obtained by reacting the compound represented by formula III and the compound represented by formula IV with N,N-diisopropylethylamine (DIPEA).

[0029]

[0030] In Formula III and Formula II, the definitions of R1 and R2 are the same as those in Formula I, and R1 and R2 are selected from any one of the following groups:

[0031] R1=H; OH; OBn; F; Cl; Br; I; OMe; OEt; OPr; OBu;

[0032] R2=H; OH; OMe; OEt; OPr; Me; Et; Pr; F; Cl; Br; I;

[0033]

[0034] In the step of constructing the structure of formula II, the reaction is carried out in an organic solvent, and the organic solvent is selected from at least one of the following: acetonitrile, tetrahydrofuran, acetone, dichloromethane, and N,N-dimethylformamide, preferably acetonitrile.

[0035] The compound represented by formula III, the compound represented by formula IV, N,N-diisopropylethylamine, and the organic solvent (acetonitrile) are used in a ratio of (1-20) mmol: (1-20) mmol: (2.5-50) mmol: (100-2000) mL, respectively. In the reaction step, the reaction temperature is room temperature, and the reaction time is 6 hours to 8 hours.

[0036] Another object of the present invention is to provide the application of the compound represented by the above formula I.

[0037] The application of the compound represented by formula I provided by the present invention is selected from at least one of the following aspects:

[0038] 1) As a reagent for ion pair recognition;

[0039] 2) ion pair recognition;

[0040] 3) Preparation of ion-pair bridged organic framework materials.

[0041] The ion pair is an ion pair of an alkali metal and an alkaline earth metal halide.

[0042] The present invention also protects a class of ion-pair bridged organic framework materials.

[0043] The ion-pair bridged organic framework material protected by the present invention is formed by the compound represented by formula I and lithium perchlorate or calcium bromide.

[0044] Furthermore, the molar ratio of the compound represented by formula I to lithium perchlorate or calcium bromide is 1:1-1:4, specifically 1:2.

[0045] The method for preparing the ion-pair bridged organic framework material comprises the following steps: slowly diffusing ether vapor into a mixed solution of the compound represented by formula I and lithium perchlorate / calcium bromide in acetonitrile and chloroform at room temperature.

[0046] The mass ratio of the compound represented by formula I to lithium perchlorate / calcium bromide is 1:3-1:5.

[0047] The volume ratio of acetonitrile to chloroform in the acetonitrile-chloroform mixed solution is 1:1-9:1.

[0048] The diffusion time of the ether vapor is 4 to 7 days.

[0049] The present invention also protects the application of the above ion-pair bridged organic framework material.

[0050] The application of the ion-pair bridged organic framework material is selected from at least one of the following aspects:

[0051] 1) Acting as an adsorbent to absorb radioactive waste gas;

[0052] 2) Adsorb radioactive waste gas.

[0053] In the present invention, the radioactive waste gas includes but is not limited to: iodine vapor, xenon, krypton and other harmful gases.

[0054] The present invention uses cheap and readily available raw materials, starting from cyanuric chloride and several cheap and readily available nucleophilic reagents, to prepare a super macrocyclic compound having a crown ether chain-linked tetraoxacalix[2]arene[2]triazine skeleton through a simple nucleophilic substitution reaction. The compound with benzyl protection is then deprotected to obtain a super macrocyclic compound having a crown ether chain-linked tetraoxacalix[2]arene[2]triazine skeleton. This super macrocyclic compound has good ion pair recognition ability and the ion pair bridged organic framework material constructed therefrom is used in the adsorption of radioactive waste gas. The reaction conditions for constructing the super macrocyclic compound are relatively mild, and the constructed ion pair bridged organic framework material has good practicality and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Schematic diagram of the ion pair solid-liquid extraction process;

[0056] Figure 2 (a)-(f) Photos of the iodine vapor adsorption process (from left to right in each photo are the blank control group, the filtered crystal powder, and the crystals); (g) Changes in iodine vapor adsorption over time at room temperature; (h) Kinetic curve fitting of iodine vapor adsorption;

[0057] Figure 3 Schematic diagram of the crystal structure of the ion-pair bridged organic framework material of I-A2 and lithium perchlorate prepared in Example 5, wherein (a) is the unit cell of the crystal and (b) is the stacking structure of the crystal;

[0058] Figure 4 Schematic diagram of the crystal structure of the ion-pair bridged organic framework material of I-A3 and calcium bromide prepared in Example 6, wherein (a) is the unit cell of the crystal and (b) is the stacking structure of the crystal. DETAILED DESCRIPTION

[0059] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.

[0060] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0061] Example 1: Preparation of the macrocyclic ring of formula II-A1

[0062] The reaction formula is as follows:

[0063]

[0064] The specific preparation method is as follows:

[0065] To a clean two-necked flask, add a magnet, the compound represented by Formula IV (8.01 g, 15 mmol), and N,N-diisopropylethylamine (4.85 g, 37.5 mmol) and dissolve them in 1300 mL of acetonitrile. Under argon, the compound represented by Formula III-A1 (3.24 g, 15 mmol) was dissolved in 200 mL of acetonitrile. This acetonitrile solution of the compound represented by Formula III-A1 was slowly added dropwise to the two-necked flask over 2 hours. The reaction was allowed to proceed at room temperature for 6 hours. The solvent was then dried and the product was purified by column chromatography (silica gel 100-200 mesh, eluent: petroleum ether / ethyl acetate = 1:1, v / v) to obtain 4.14 g of the compound represented by Formula II-A1 in a 56% yield.

[0066] 1 H NMR (DMSO-d6, 500MHz) δ (ppm) 7.37-7.21 (m, 6H), 7.12 (s, 2H), 4.92 (s, 2H), 4.38 (t, J = 4.4Hz, 4H), 3.67 (t, J = 4.6Hz, 4H), 3.46 (m, 12H);

[0067] 13 C NMR (DMSO-d6, 125MHz) δ (ppm) 172.4, 172.2, 171.8, 145.2, 142.4, 136.6, 128.6, 128.5, 127.8, 124.5, 121.6, 75.5, 70.3, 68.9, 68.2;

[0068] HR-ESI-MS(positive ion mode)m / z:[M+H] + calcd for C 29 H 31 Cl2N6O9:677.1524,found:677.1518.

[0069] From the above, it can be seen that the structure of the above compound is correct and is indeed the compound represented by formula II-A1.

[0070] Example 2: Preparation of benzyl-protected macrocyclic formula I-A1 shown in general formula I

[0071] The reaction formula is as follows:

[0072]

[0073] The specific preparation method is as follows:

[0074] To a clean two-necked flask, add a magnet, the compound represented by Formula II-A1 (2.51 g, 4.00 mmol), the compound represented by Formula III-A1 (0.86 g, 4.00 mmol), cesium fluoride (4.86 g, 32.00 mmol), and 400 mL of acetonitrile. Reflux for 1.5 hours, cool to room temperature, evaporate the solvent, and perform column chromatography (100-200 mesh silica gel, eluent: dichloromethane / acetone = 6:1-4:1, v / v) to obtain 377 mg of the compound represented by Formula I-A1 in a 12% yield.

[0075] The preparation method of the compound represented by Formula II-A1 is detailed in Example 1.

[0076] 1 H NMR(d6-DMSO,500MHz)δ(ppm)7.07-6.99(m,24H),6.91(d,J=7.2Hz,8H),4.72(s,8H),4.39(t,J=4.5Hz,8H),3.70(t,J=4.5Hz,8H),3.57–3.53(m,24H);

[0077] 13 C NMR (DMSO-d6, 125MHz) δ (ppm) 174.0, 173.1, 145.3, 142.7, 136.6, 128.3, 128.0, 127.2, 124.2, 121.1, 74.9, 70.4, 70.3, 70.3, 68.4, 68.2;

[0078] HR-ESI-MS(positive mode)m / z:[M+Na] + calcd for C 84 H 80 N 12 O 24 Na:1663.5301,found:1663.5314.

[0079] From the above, it can be seen that the structure of the above compound is correct, and it is the compound represented by formula I-A1.

[0080] Example 3: Preparation of Hydroxyl Supermacrocyclic Formula I-A2 Represented by General Formula I

[0081] The reaction formula is as follows:

[0082]

[0083] The specific preparation method is:

[0084] To a clean two-necked flask, add a magnet, the compound represented by Formula I-A1 (250 mg, 0.00015 mmol), and 100 mg of palladium on carbon. Stir at room temperature under a hydrogen atmosphere for 24 hours. Stop the reaction, filter through celite to remove the palladium on carbon, and spin-dry the solvent. Recrystallize the product from acetonitrile, methanol, and diethyl ether (dissolve the dried product in a 1:1 mixture of 0.5-2 ml of methanol and acetonitrile, then add 5-50 ml of diethyl ether to precipitate a white solid. Filter and wash the white solid with diethyl ether to obtain the compound represented by Formula I-A2). 95 mg of the compound represented by Formula I-A2 was obtained in a 50% yield.

[0085] 1 H NMR(DMSO-d6,500MHz)δ(ppm)9.38(s,4H),6.85(d,J=8.0Hz,8H),6.63(t,J=8.4Hz,4H),4 .59(t,J=4.7Hz,8H),3.83–3.76(t,J=4.0Hz,8H),3.62-3.60(m,8H),3.57–3.55(m,16H);

[0086] 13 C NMR (DMSO-d6, 125MHz) δ (ppm) 173.9, 173.2, 142.1, 141.2, 120.4, 118.6, 70.3, 70.3, 70.3, 68.65, 67.9;

[0087] HR-ESI-MS(negative mode)m / z:[MH] - calcd for C 56 H 56 N 12 O 24 :1279.3447,found:1279.3468.

[0088] From the above, it can be seen that the structure of the above compound is correct, and it is the compound represented by formula I-A2.

[0089] The preparation method of the compound represented by Formula I-A1 is detailed in Example 2.

[0090] Example 4: Experimental study of ion pair performance

[0091] The differently substituted supermacrocyclic compounds prepared in the present invention are used as ion pair receptors to explore their ion pair recognition capabilities with common alkali metal and alkaline earth metal halides.

[0092] We applied this series of synthesized super-macrocyclic compounds to the recognition of common alkali metal and alkaline earth metal halides, realizing ion pair recognition based on anion-π interaction / hydrogen bonding and synergistic ion-dipole interaction.

[0093]

[0094]

[0095] The specific preparation method is:

[0096] Add the macrocyclic compound represented by formula I-A2 or formula I-A3 (1 mmol) and the halide of alkali metal or alkaline earth metal (3 mg) to a clean NMR tube, add 0.5 mL of deuterated chloroform, and ultrasonicate at room temperature for 2 minutes. 1 Changes in H NMR spectra are used to measure the presence of host-guest interaction. In the presence of the host, when significant host-guest interaction occurs, i.e., during solid-liquid extraction (SLI), where the host extracts the guest from the solid phase into an organic solvent, a distinct chemical shift is observed. Because these individual ion-pair guests are poorly soluble in deuterated chloroform, the addition of salt causes simultaneous changes in the chemical shifts of the aromatic protons (anion binding sites) and the ethylene glycol chains (cation binding sites), reflecting the binding behavior of the ion pair. We divide the observed results into the following four types of ion pair binding: (1) There is no obvious change in the hydrogen spectrum of the system before and after the addition of the host and guest (indicated by "N" in the table), indicating that there is no obvious interaction between the host and the guest; (2) There is an obvious change in chemical shift before and after the addition of the guest, and only one set of nuclear magnetic resonance signals is observed (indicated by "F" in the table), indicating that there is an interaction between the host and the guest; (3) There is a significant change in the hydrogen spectrum after the addition of the guest, and two sets of nuclear magnetic resonance signals are observed (indicated by "S" in the table), indicating that there is a strong interaction between the host and the guest; (4) After the addition of the guest, the hydrogen spectrum of the host weakens to disappear, indicating that there is an interaction between the host and the guest, and the formed complex has poor solubility in deuterated chloroform, that is, coprecipitation occurs (indicated by "P" in the table), and thus precipitates from the system.

[0097] It was found that lower and upper edge substituents affect ion pair binding. Formulas I-A3 and I-A2 are relatively good ion pair acceptors compared to I-A4, indicating that the introduction of upper edge substituents is detrimental to ion pair binding. Compared to Formulas I-A3 and I-A2, Formula I-A2 introduces a hydroxyl group at the lower edge. I-A2 exhibits fast NMR exchange with all salts except LiCl(N) and CaBr2(P), while I-A3 selectively binds to CaBr2. All supermacrocycles possess the same cation binding site, and the difference in ion pair binding ability may arise from the synergistic interaction between the anion binding site (subcavity) and the anion-cation site. Formulas I-A3 and I-A4 provide the same anion-π bonding site, while I-A2 provides an anion interaction site that is synergistic with both anion-π and hydrogen bonding. Thus, the anion-π interaction promotes the selectivity of ion pair binding, while the synergistic interaction between anion-π and hydrogen bonding improves its compatibility with various salts.

[0098] Subsequently, ion-pair complexes of formula I-A3-CaBr2 and formula I-A2-NaI were selected for quantitative investigation (maximum chemical shift change Δδs > 0.15 ppm). Solution-state NMR titrations were performed with the supermacrocyclic compound using a halide anion (tetrabutylammonium salt as the counter cation) and a cation (BARF salt as the counter anion). Cation binding was reflected by downfield shifts of ethylene glycol protons, while anion binding was reflected by downfield shifts of aromatic protons. The binding constants for both anions and cations were calculated based on a stoichiometric ratio of 1:2. The table below shows the binding constants for the anions and cations. As expected, the supermacrocyclic compound exhibited strong binding capacity for both anions and cations. Subsequently, NMR titrations were performed by adding anions to the complexes of the supermacrocyclic compound with two equivalents of cations to investigate their binding to the ion pairs.

[0099]

[0100] Example 5: Preparation of an ion-pair bridged organic framework material of general structural formula I-A2 and lithium perchlorate

[0101] The single crystal structure is Figure 3 shown.

[0102] The specific preparation method is:

[0103] Compound I-A2 (3 mg) and lithium perchlorate (1 mg) were added to a clean sample vial. By slowly diffusing diethyl ether vapor into a 1:1, v / v, acetonitrile-chloroform mixture of compound I-A2 and lithium perchlorate at room temperature for four days, we successfully obtained the single crystal structure of a 1:2 (molar ratio) complex of compound I-A2 and lithium perchlorate. The structure was identified by X-ray diffraction. The resulting ion-pair-bridged organic framework exhibited a large cavity.

[0104] Chemical formula: C 68 H 74 Cl2Li2N 18 O 32

[0105] a=42.5681(8); b=42.5681(8); c=11.8355(2); α=90.0; β=90.0; γ=120.0; V=18573.1(8).

[0106] From the above, it can be seen that the structure of the above compound is correct, and it is a crystal of formula I-A2 and lithium perchlorate.

[0107] The preparation method of the compound represented by Formula I-A2 is detailed in Example 3.

[0108] Example 6: Preparation of an ion-pair bridged organic framework material of general structural formula I-A3 and calcium bromide

[0109] The single crystal structure is Figure 4 shown.

[0110] The specific preparation method is:

[0111] Compound I-A3 (3 mg) and calcium bromide (1 mg) were added to a clean sample vial. By slowly diffusing diethyl ether vapor into a mixture of compound I-A3 and calcium bromide in acetonitrile and chloroform (1:1, v / v, containing 3% methanol) at room temperature for 6 days, we successfully obtained a single crystal structure of a complex of compound I-A3 and calcium bromide in a 1:2 molar ratio. The structure was identified by X-ray diffraction. The resulting ion-pair-bridged organic framework exhibited a large cavity.

[0112] Chemical formula: C 56 H 56 Br4Ca2N 12 O 20

[0113] a=18.9752(3); b=24.7105(5); c=18.4263(5); α=90.0; β=90.0; γ=90.0; V=8639.9(3).

[0114] From the above, it can be seen that the structure of the above compound is correct, which is a 1:2 complex of the compound shown in I-A3 and calcium bromide.

[0115] The preparation method of the compound represented by Formula I-A3 is detailed in Example 2.

[0116] Example 7: Adsorption experiment of iodine by ion-pair bridged organic framework material formed by compound represented by formula I-A3 and calcium bromide

[0117] The specific experimental methods are as follows:

[0118] 3 mg of crystals formed by the compound shown in I-A3 and calcium bromide (the ion-pair bridged organic framework material prepared in Example 6) were added to a clean small sample vial, which was then placed in a large sample vial containing elemental iodine. The change in the mass of the sample vial containing the crystals was measured to investigate the adsorption process of elemental iodine over time.

[0119] Figure 2 (a)-(f) Photographs of the iodine vapor adsorption process (from left to right in each photo, a blank control group, filtered crystal powder, and crystals); (g) Changes in iodine vapor adsorption over time at room temperature; (h) Kinetic curve fitting of iodine vapor adsorption. The blank control group was treated with no crystals, with only iodine vapor introduced; the filtered crystals were the powder group, obtained by filtering the ion-pair bridged organic framework material prepared in Example 6 (after filtration, the pores of the ion-pair bridged organic framework material may collapse, but the chemical composition remains unchanged).

[0120] Depend on Figure 2 It can be seen that this ion-pair bridged organic framework material can adsorb iodine vapor and is expected to be used as an adsorption material for iodine vapor.

[0121] From the above results, it can be seen that the ion-pair bridged organic framework material prepared by the present invention has sub-macrocyclic and super-macrocyclic cavities, and shows good capture ability for iodine vapor, with the maximum adsorption capacity reaching 117 wt% at 96 h.

Claims

1. A type of crystal / organic metal framework material formed by the compound represented by Formula I and lithium perchlorate or calcium bromide; In the general structural formula of Formula I, R1 and R2 are selected from any one of the following groups:

2. The ion-pair bridged organic framework material according to claim 1, characterized in that: The molar ratio of the compound represented by formula I to lithium perchlorate or calcium bromide is 1:1-1:

4.

3. The method for preparing the ion-pair bridged organic framework material according to claim 1 or 2, comprising the following steps: At room temperature, diethyl ether vapor is diffused into a mixed solution of the compound represented by formula I and lithium perchlorate or calcium bromide in acetonitrile and chloroform.

4. The preparation method according to claim 3, wherein: The mass ratio of the compound represented by Formula I to lithium perchlorate / calcium bromide is 1:3-1:

5. Alternatively, the volume ratio of acetonitrile to chloroform in the acetonitrile-chloroform mixed solution is 1:1-9:1; Alternatively, the diffusion time of the ether vapor is 4 to 7 days.

5. The use of the ion-pair bridged organic framework material according to claim 1 or 2, wherein the use is selected from at least one of the following aspects: 1) Acting as an adsorbent to absorb radioactive waste gas; 2) Adsorption of radioactive waste gas; Preferably, the radioactive waste gas includes but is not limited to the following harmful gases: iodine vapor, xenon gas, and krypton gas.

6. A super macrocyclic compound having a tetraoxacalix[2]arene[2]triazine skeleton connected by a crown ether chain, the general structural formula of which is shown in Formula I: In the general structural formula of Formula I, R1 and R2 are selected from any one of the following groups:

7. A method for preparing the compound of formula I according to claim 6, comprising the steps of: Reacting the compound represented by formula II with the compound represented by formula III to obtain the compound represented by formula I; In the formula II and formula III, the definitions of R1 and R2 are the same as those in the aforementioned formula I, and R1 and R2 are selected from any one of the following groups:

8. The preparation method according to claim 7, characterized in that: When R1 and R2 in the formula I are selected from any one of the following, the method further comprises: a step of deprotecting the benzyl group:

9. The preparation method according to claim 7 or 8, characterized in that: The reaction is carried out in an organic solvent, and the organic solvent is selected from at least one of the following: acetonitrile, tetrahydrofuran, acetone, dichloromethane, N,N-dimethylformamide, preferably acetonitrile; Alternatively, the reaction is carried out under alkaline conditions, and the base is selected from at least one of the following: cesium fluoride, N,N-diisopropylethylamine, potassium carbonate, sodium carbonate, sodium hydroxide, and cesium carbonate, preferably cesium fluoride; Alternatively, in the reaction, the compound represented by Formula II, the compound represented by Formula III, the base, and the organic solvent are used in a ratio of (1-5) mmol: (1-5) mmol: (8-40) mmol: (100-500) mL, respectively; in the reaction, the reaction temperature is 24-120° C., and the reaction time is 1-48 hours.

10. Compound represented by formula II: In the formula II, R1 and R2 are defined the same as those in the above formula I, and R1 and R2 are selected from any one of the following groups:

11. The method for preparing the compound of formula II according to claim 10, comprising the steps of: reacting the compound of formula III and the compound of formula IV with N,N-diisopropylethylamine (DIPEA); In Formula III and Formula II, the definitions of R1 and R2 are the same as those in Formula II, and are selected from any one of the following groups: Preferably, the reaction is carried out in an organic solvent, and the organic solvent is selected from at least one of the following: acetonitrile, tetrahydrofuran, acetone, dichloromethane, N,N-dimethylformamide; Preferably, the compound represented by formula III, the compound represented by formula IV, N,N-diisopropylethylamine, and the organic solvent are used in a ratio of (1-20) mmol: (1-20) mmol: (2.5-50) mmol: (100-2000) mL, respectively; in the reaction step, the reaction temperature is room temperature, and the reaction time is 6-8 hours.

12. The use of the compound of formula I according to claim 6, selected from at least one of the following aspects: 1) As a reagent for ion pair recognition; 2) ion pair recognition; 3) Preparation of ion-pair bridged organic framework materials; Preferably, the ion pair is an ion pair of an alkali metal and an alkaline earth metal halide.

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