Covalent molecular nanotubes, methods of making and using the same

Abstract

This invention discloses a covalent molecular nanotube, its preparation method, and its applications. The covalent molecular nanotube has a three-dimensional tubular structure with a cavity, formed by repeating units as shown in Formula I. In this invention, rigid ring-p-phenylene oxides are used as the core building blocks, giving the covalent molecular nanotube radial conjugation and inherent cavity structural characteristics. The radial dimension of the material is controlled by adjusting the number of repeating units. Boronate bonds are used as connecting units to efficiently drive the axial connection of the ring-p-phenylene oxides, and the substituent Q is controlled... 4 The selection of functional groups enables the modular and customized synthesis of covalent molecular nanotubes of different sizes and structures. Furthermore, it has been found that these covalent molecular nanotubes have a large specific surface area and possess nanopores, thus showing potential applications in gas separation and storage.

Description

Technical Field

[0001] This invention relates to the field of preparation of cyclic p-phenylene molecules. More specifically, it relates to a covalent molecular nanotube, its preparation method, and its applications. Background Technology

[0002] Porous materials, due to their high specific surface area, tunable pore size, and excellent surface activity, are widely used in gas adsorption, catalysis, separation, and sensing. With the rapid development of synthetic chemistry and materials science, porous materials, represented by network structures such as zeolites, covalent organic frameworks (COFs), and metal-organic frameworks (MOFs), have made significant progress. However, their poor processability limits their applications. In contrast, molecular porous materials, with their precise structure and good solubility, exhibit superior processability and are gradually becoming a research hotspot.

[0003] Based on their structural characteristics, molecular porous materials can be further divided into molecular cages and molecular nanotubes. Compared with the more widely studied molecular cages, molecular nanotubes possess unique anisotropy and one-dimensional confined cavities, making them a promising functional carrier with significant application potential. The synthesis of molecular nanotubes typically relies on macrocyclic structures linked by axial multiple covalent bonds. However, due to limitations in the building blocks, molecular nanotubes with large specific surface areas have not yet been effectively synthesized.

[0004] Cycloparaphenylene (CPP) is a class of rigid macrocyclic molecules with a radially conjugated structure. Its rigidity allows it to maintain its inherent cavity during axial assembly, while its radial conjugation facilitates abundant CH…π interactions with gas molecules, thereby enhancing gas adsorption capacity. Based on these characteristics, CPP has become an ideal building block for molecular nanotubes. However, only a few studies have reported on the construction of molecular nanotubes using CPP as the core building block, and the CPP molecules are all connected by strong covalent bonds, resulting in low synthesis efficiency and difficulty in flexibly controlling the size of molecular nanotubes, hindering in-depth research on their porous properties.

[0005] In summary, there is an urgent need in this field to develop novel molecular nanotube structures with flexible control over their size, so as to facilitate modular and customized molecular nanotube synthesis and to explore the porous properties of such molecular nanotubes. Summary of the Invention

[0006] To address the aforementioned problems, the first objective of this invention is to provide a covalent molecular nanotube. This covalent molecular nanotube is achieved by controlling the number of repeating units and the substituent Q. 4The selection of functional groups enables the control of the material's size. Specifically, the radial dimension of the material is altered by controlling the number of repeating units, and the size of the substituent Q is controlled. 4 The choice of functional groups can be used to change the axial dimensions of the material.

[0007] The second objective of this invention is to provide a method for preparing covalent molecular nanotubes as described above.

[0008] A third objective of this invention is to provide an application of covalent molecular nanotubes as described above in gas separation and storage.

[0009] To achieve the first objective mentioned above, the present invention adopts the following technical solution:

[0010] This invention discloses a covalent molecular nanotube, wherein the structure of the covalent molecular nanotube is a three-dimensional tubular structure formed by enclosing the structure shown in Formula I as a repeating unit;

[0011]

[0012] Among them, Q 1 Q 2 Q 3 Each of these can be independently represented by one of the following: halogen, NRH, OR, and R, where R is selected from H and C. 1-10 Alkyl, C 1-10 Acyl group, C 6-20 One of the aryl groups;

[0013] Q 4 Selected from C 1-10 Alkyl, C 6-20 One of the aryl groups;

[0014] n is an integer ranging from 3 to 10.

[0015] Furthermore, the Q 1 Q 2 Q 3 H represents;

[0016] The Q 4 Selected from 1,4-disubstituted benzene or 4,4'-disubstituted biphenyl.

[0017] Furthermore, n can be 3 or 4.

[0018] Furthermore, the covalent molecular nanotubes are selected from one of the following structures:

[0019]

[0020]

[0021] Terminology Explanation and Description

[0022] Unless otherwise stated, the definitions of groups and terms recorded in this application specification and claims, including their definitions as examples, preferred definitions, and definitions of specific compounds in the embodiments, can be arbitrarily combined and combined with each other. Such combinations and combinations of group definitions and compound structures shall fall within the scope of this application.

[0023] Unless otherwise stated, superscripts for groups in this application are group designations, and subscripts generally indicate the number of groups.

[0024] The "C" used alone or as a suffix or prefix in this invention 1-10 "Alkyl" refers to branched and straight-chain saturated aliphatic hydrocarbon groups having 1 to 10 carbon atoms (or, if the specific number of carbon atoms is provided), such as "C". 1-6 Alkyl group. The "C" 1-4 "Alkyl" refers to an alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, and all isomers of the above groups.

[0025] Term "C" 6-20 "Aryl" should be understood as representing a monocyclic, bicyclic, or tricyclic hydrocarbon ring with 6 to 20 carbon atoms that is monovalent and partially aromatic, such as "C". 6-14 Aryl. The term "C" 6-14 "Aryl" should be understood as representing a monovalent aromatic or partially aromatic monocyclic, bicyclic, or tricyclic hydrocarbon ring ("C") having 6, 7, 8, 9, 10, 11, 12, 13, or 14 carbon atoms. 6-14 Aryl), particularly a ring with 6 carbon atoms (“C6 aryl”), such as phenyl; a ring with 7 carbon atoms (“C7 aryl”), such as benzyl; or biphenyl, or a ring with 9 carbon atoms (“C9 aryl”), such as indenyl or indenyl, or a ring with 10 carbon atoms (“C…”). 10 Aryl groups, such as tetrahydronaphthyl, dihydronaphthyl, or naphthyl, or rings with 13 carbon atoms (“C”). 13 Aryl groups, such as fluorene groups, or rings with 14 carbon atoms (“C”). 14 Aryl), for example, anthracene.

[0026] To achieve the second objective mentioned above, the present invention adopts the following technical solution:

[0027] This invention discloses a method for preparing covalent molecular nanotubes as described above, comprising the following steps:

[0028]

[0029] S1. Compound I-1 and anhydrous tetrahydrofuran were added to the reactor. Butyllithium was added at -78°C. After stirring for 1.5-2 hours, compound I-2 was added. The mixture was then heated to room temperature and stirred for 10-12 hours. After the reaction was completed, the mixture was quenched with water, the organic phase was collected, the aqueous phase was extracted with ethyl acetate, the organic phases were combined, washed with saturated brine, dried with anhydrous sodium sulfate, and rotary evaporated to obtain compound I-3.

[0030] S2. Sodium hydride was added to tetrahydrofuran and cooled to below 0°C. Compound I-3 was added to the mixture. After stirring at room temperature, iodomethane was added and stirring was continued for 15-20 hours. After the reaction was completed, the mixture was quenched with water, the organic phase was collected, the aqueous phase was extracted with ethyl acetate, the organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and purified by rotary evaporation and column chromatography to obtain compound I-4.

[0031]

[0032] S3. Add Ni(cod)2, 2,2'-bipyridine, THF and compound I-4 to the reactor and stir at 60-70℃ for 12-15h. After the reaction is completed, pass through a column and evaporate by rotary evaporation to obtain an intermediate. Add H2SnCl4 to the solution containing the intermediate at below 0℃ and stir at room temperature for 3-4h. After the reaction is completed, quench with NaOH solution, filter, evaporate by rotary evaporation, and purify by column chromatography to obtain compound I-5.

[0033]

[0034] S4. Add BBr3 to a solution containing compound I-5 at -78℃ or below, stir at room temperature for 3 hours, quench with water after the reaction is complete, and then evaporate by rotary evaporation to obtain compound I-6.

[0035]

[0036] S5. Mix compounds I-6 and I-7 with the solvent and stir at room temperature for 15-18 hours. After the reaction is complete, evaporate by rotary evaporation to obtain compound I.

[0037] Furthermore, in step S1, the molar ratio of compound I-1, compound I-2, and n-butyllithium is 2-3:1:2-3.

[0038] Furthermore, in step S2, the molar ratio of compound I-3, sodium hydride, and iodomethane is 1:2-5:2-5.

[0039] Furthermore, in step S3, the molar ratio of compound I-4, Ni(cod)2 and 2,2'-bipyridine is 1:1 to 2:1 to 2, and the molar ratio of intermediate and H2SnCl4 is 1:3 to 100.

[0040] Furthermore, in step S4, the molar ratio of compound I-5 to BBr3 is 1:3 to 100;

[0041] In step S5, the molar ratio of compound I-6 to compound I-7 is 2:3 to 5.

[0042] To achieve the third objective mentioned above, the present invention adopts the following technical solution:

[0043] This invention discloses an application of covalent molecular nanotubes as described above in gas separation and storage.

[0044] The beneficial effects of this invention are as follows:

[0045] This invention uses rigid ring-p-phenylene oxides as core building blocks, endowing covalent molecular nanotubes with radial conjugation and inherent cavity structural characteristics. The radial dimension of the material is controlled by adjusting the number of repeating units. Boronate bonds are used as connecting units to efficiently drive the axial connection of the ring-p-phenylene oxides, and the radial dimension is controlled by adjusting the substituent Q. 4 The selection of functional groups allows for the modular and customized synthesis of covalent molecular nanotubes of different sizes and structures. Taking compound 1 as an example, the axial dimension of a single crystal of the covalent molecular nanotube is 1.46 nm, and the radial dimension is 1.24 nm.

[0046] This invention can produce ring-p-phenylene blocks of various radial dimensions in a single batch during the preparation of ring-p-phenylene blocks, thereby improving construction efficiency.

[0047] The covalent molecular nanotubes prepared by this invention have a large specific surface area and possess nanopores. Taking compound 1 as an example, its specific surface area is 1241 m². 2 The pore size distribution is below 1.5 nm, indicating that the structure is porous and has potential applications in gas separation and storage. Attached Figure Description

[0048] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0049] Figure 1 A schematic diagram of the crystal structure of compound 1 is shown.

[0050] Figure 2 A schematic diagram of the crystal stacking structure of compound 1 is shown.

[0051] Figure 3A and Figure 3BThe N2 adsorption-desorption curves and pore size distribution diagrams of compound 1 obtained in the N2 adsorption-desorption test are shown below. Detailed Implementation

[0052] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0053] Synthesis Examples

[0054] Compound 6

[0055]

[0056] 1,4-Dibromobenzene (2.60 g, 11 mmol, 2.2 equiv) and anhydrous tetrahydrofuran (30 mL) were added to a 250 mL round-bottom flask. Butyllithium (4.4 mL, 11 mmol, 2.2 equiv) was added to the above solution at -78 °C. The reaction mixture was stirred at -78 °C for 1.5 h. Then, compound 4 (840 mg, 5.0 mmol, 1.0 equiv) was added at -78 °C. The reaction mixture was heated to 25 °C and stirred for 12 h. After the reaction was complete, the mixture was quenched with water, and the aqueous phase was extracted with ethyl acetate. The organic and inorganic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation to give a brown oily intermediate 5. Sodium hydride (800 mg, 20 mmol, 4.0 equiv) was suspended in 50 mL of tetrahydrofuran and cooled to 0 °C. Intermediate 5 was added to the sodium hydride suspension at 0 °C, and the mixture was stirred at room temperature for 1 h. Then, iodomethane (2.84 g, 20 mmol, 4.0 equiv) was added, and the mixture was stirred at room temperature for 16 h. After the reaction was complete, the mixture was quenched with water and extracted with ethyl acetate. The organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate. The solvent was removed by rotary evaporation, and the mixture was purified by column chromatography to give a white solid compound 6 (892 mg, 35% yield).

[0057] 1 H NMR (600MHz, CDCl3) δ7.47 (d, J = 8.5 Hz, 4H), 7.35 (d, J = 8.5 Hz, 4H), 5.81 (s, 2H), 3.58 (s, 6H), 3.47 (s, 6H);

[0058] 13 C NMR (151MHz, CDCl3) δ143.0,141.1,132.4,131.5,128.4,122.0,79.4,60.0,52.3;

[0059] IR(film):2936,2818,1643,1482,1395,1268,1991,1073,1009,876,814cm -1 ;

[0060] HRMS (MALDI): [M] + calcd for C 22 H 22 Br2O4 507.9879, found 507.9881.

[0061] Compound 7 and Compound 8

[0062]

[0063] Ni(cod)₂ (825 mg, 3.0 mmol, 2.0 equiv), 2,2'-bipyridine (470 mg, 3.0 mmol, 2.0 equiv), and THF (50 mL) were added to a reaction flask. The reaction mixture was stirred at room temperature for 10 min. Compound 6 (765 mg, 1.5 mmol, 1.0 equiv) was added, and the mixture was stirred at 65 °C for 15 h. After the reaction was completed, the mixture was filtered through a short silica gel column, and the solvent was evaporated to dryness to obtain a brown intermediate. The crude product and 100 mL of THF were added to a round-bottom flask. 30 mL of H₂SnCl₄ stock solution (12 mmol, 8 equiv) was added to the above solution at 0 °C, and the mixture was stirred at room temperature for 3 h. After the reaction was completed, the mixture was quenched with NaOH solution, filtered through diatomaceous earth, and the solvent was removed by rotary evaporation. The mixture was purified by column chromatography to obtain a yellow solid 7 (205 mg, yield 47%) and a white solid 8 (36 mg, yield 8%).

[0064] Compound 7:

[0065] 1 H NMR (600MHz, CDCl3) δ7.60 (d, J = 8.7Hz, 12H), 7.54 (d, J = 8.7Hz, 12H), 6.63 (s, 6H), 4.00 (s, 18H);

[0066] 13 C NMR (151MHz, CDCl3) δ150.8,138.9,137.8,131.8,128.5,128.0,127.1,62.4;

[0067] IR(film):2931,1472,1378,1217,1123,1006,802,736cm -1 ;

[0068] HRMS (MALDI): [M] + calcd for C 60 H 48 O6864.3445, found 864.3475.

[0069] Compound 8:

[0070] 1 H NMR (600MHz, CDCl3) δ7.64 (q, J = 8.7Hz, 32H), 6.78 (s, 8H), 3.95 (s, 24H);

[0071] 13 C NMR (151MHz, CDCl3) δ151.0,139.2,137.9,133.0,128.6,127.8,127.1,62.1;

[0072] IR(film):2935,1593,1472,1383,1221,1120,1006,806,741cm -1 ;

[0073] HRMS (MALDI): [M] + calcd for C 80 H 64 O81152.4596, found 1152.4616.

[0074] Compound 9

[0075]

[0076] Add 50 mL of CH2Cl2 containing compound 7 (156 mg, 0.18 mmol) to a flask. Slowly add BBr3 (1.0 M in CH2Cl2, 3.2 mL, 3.2 mmol, 18 equiv) to the above solution at -78 °C. Stir at room temperature for 3 h. After the reaction is complete, quench with water and remove the solvent by rotary evaporation. Wash the obtained solid with deionized water and dry to give a yellow solid compound 9 (115 mg, yield 82%).

[0077] 1 H NMR (600MHz, DMSO-d6) δ9.31 (s, 6H), 7.66 (d, J = 8.9Hz, 12H), 7.62 (d, J = 8.8Hz, 12H), 6.44 (s, 6H);

[0078] 13C NMR (151MHz, DMSO-d6) δ143.4,137.9,137.3,127.5,126.4,126.0,123.8;

[0079] IR(film):3438,3037,2832,1593,1469,1383,1309,1218,1118,1006,805,742cm -1 ;

[0080] HRMS (MALDI): [M] + calcd for C 54 H 36 O6780.2506, found 780.2539.

[0081] Compound 1

[0082]

[0083] 1,4-phenyldiboronic acid (35 mg, 0.21 mmol, 1.5 equiv), compound 9 (109 mg, 0.14 mmol, 1.0 equiv), 20 mL chloroform and 2 mL methanol were added to the reaction flask. The mixture was stirred at room temperature for 15 h, the solvent was removed by rotary evaporation, the solid was washed with dichloromethane and dried to give a yellow solid compound 1 (106 mg, yield 82%).

[0084] 1 H NMR (600MHz, CDCl3) δ8.35 (s, 12H), 8.04 (d, J = 8.5Hz, 24H), 7.54 (d, J = 8.9Hz, 25H), 7.46 (s, 12H);

[0085] 13 C NMR (151MHz, DMSO-d6) δ149.9,136.7,135.8,133.0,130.8,127.1,126.2,119.7,119.0;

[0086] IR(film):3031,1593,1520,1480,1366,1328,1219,1107,828,797,739,671cm -1 ;

[0087] HRMS (MALDI): [M] + calcd for C 126 H 72 B6O 12 1842.5577, found 1842.5596.

[0088] Single-crystal diffraction revealed that the crystal structure of compound 1 is as follows: Figure 1 As shown, compound 1 exhibits an ideal tubular structure in the crystalline state, with two rings of phenylene molecules arranged in parallel and maintaining axial alignment. The height of the nanotube is 1.46 nm and the diameter is 1.24 nm.

[0089] Figure 2 The schematic diagram of the crystal stacking structure of compound 1 shows that there are long-range ordered one-dimensional through-pores in its crystal stacking structure, which demonstrates its characteristics as a potential new type of molecular porous material.

[0090] N2 adsorption-desorption tests were performed on compound 1. The N2 adsorption-desorption curve of compound 1 at 77 K is shown in [reference needed]. Figure 3A See aperture distribution diagram. Figure 3B The results showed that the BET specific surface area of ​​compound 1 was 1241 m². 2 / g, whose pore size distribution is consistent with the crystal structure, indicates that the structure is porous and has potential applications in gas separation and storage.

[0091] Compound 2

[0092]

[0093] 4,4'-Biphenyldiboronic acid (7 mg, 0.03 mmol, 1.5 equiv), compound 9 (15.6 mg, 0.02 mmol, 1.0 equiv), 5 mL chloroform and 1 mL methanol were added to the reaction flask. The mixture was stirred at room temperature for 15 h, and the solvent was removed by rotary evaporation. The solid was washed with dichloromethane and dried to give a yellow solid compound 2 (18 mg, yield 86%).

[0094] 1 H NMR (400MHz, DMSO-d6) δ7.96–7.83(m,24H),7.78–7.63(m,48H),6.91(s,12H).

[0095] HRMS (MALDI): [M] + calcd for C 144 H 84 B6O 12 2070.6516, found 2070.6566.

[0096] Compound 10

[0097]

[0098] Compound 8 (69 mg, 0.06 mmol) and CH2Cl2 (50 mL) were added to a flask. BBr3 (1.0 M in CH2Cl2, 4.8 mL, 4.8 mmol, 80 equiv) was slowly added to the above solution at -78 °C. The mixture was stirred at room temperature for 3 h. After the reaction was completed, water was added to quench the reaction, and the solvent was removed by rotary evaporation. The obtained solid was washed with deionized water and dried to give compound 10 (56 mg, yield 89%).

[0099] 1 H NMR(600MHz,DMSO-d6)δ9.18(s,8H),7.72–7.68(m,32H),6.56(s,8H).

[0100] Compound 3

[0101]

[0102] 1,4-Phenylated boric acid (5 mg, 0.03 mmol, 2.0 equiv), compound 10 (15.6 mg, 0.015 mmol, 1.0 equiv), 5 mL chloroform, and 1 mL methanol were added to a reaction flask. The mixture was stirred at room temperature for 15 h. The solvent was removed by rotary evaporation, and the solid was washed with dichloromethane and dried to give a yellow solid, compound 3 (31 mg, 85% yield).

[0103] 1 H NMR (400MHz, CDCl3) δ8.02 (d, J = 7.6Hz, 32H), 7.76 (d, J = 8.0Hz, 32H), 7.64 (s, 16H), 7.05 (s, 16H).

[0104] HRMS (MALDI): [M] + calcd for C 168 H 96 B8O 16 2456.7437, found 2456.7539.

[0105] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A covalent molecular nanotube, characterized in that, The structure of the covalent molecular nanotube is a three-dimensional tubular structure with a cavity, formed by enclosing the structure shown in Formula I as a repeating unit. wherein Q 1 , Q 2 , Q 3 each independently represents one of halogen, NRH, OR, R selected from H, C 1-10 alkyl, C 1-10 acyl, C 6-20 aryl; Q 4 Selected from C 1-10 Alkyl, C 6-20 One of the aryl groups; n is an integer ranging from 3 to 10.

2. The covalent molecular nanotube according to claim 1, characterized in that, The Q 1 Q 2 Q 3 H represents; The Q 4 Selected from 1,4-disubstituted benzene or 4,4'-disubstituted biphenyl.

3. The covalent molecular nanotube according to claim 1, characterized in that, The value of n is 3 or 4.

4. The covalent molecular nanotube according to claim 1, characterized in that, The covalent molecular nanotubes are selected from one of the following structures:

5. The method for preparing covalent molecular nanotubes according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Compound I-1 and anhydrous tetrahydrofuran were added to the reactor. Butyllithium was added at -78°C. After stirring for 1.5-2 hours, compound I-2 was added. The mixture was then heated to room temperature and stirred for 10-12 hours. After the reaction was completed, the mixture was quenched with water, the organic phase was collected, the aqueous phase was extracted with ethyl acetate, the organic phases were combined, washed with saturated brine, dried with anhydrous sodium sulfate, and rotary evaporated to obtain compound I-3. S2. Sodium hydride was added to tetrahydrofuran and cooled to below 0°C. Compound I-3 was added to the mixture. After stirring at room temperature, iodomethane was added and stirring was continued for 15-20 hours. After the reaction was completed, the mixture was quenched with water, the organic phase was collected, the aqueous phase was extracted with ethyl acetate, the organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and purified by rotary evaporation and column chromatography to obtain compound I-4. S3. Add Ni(cod)2, 2,2'-bipyridine, THF and compound I-4 to the reactor and stir at 60-70℃ for 12-15h. After the reaction is completed, pass through a column and evaporate by rotary evaporation to obtain an intermediate. Add H2SnCl4 to the solution containing the intermediate at below 0℃ and stir at room temperature for 3-4h. After the reaction is completed, quench with NaOH solution, filter, evaporate by rotary evaporation, and purify by column chromatography to obtain compound I-5. S4. Add BBr3 to a solution containing compound I-5 at -78℃ or below, stir at room temperature for 3 hours, quench with water after the reaction is complete, and then evaporate by rotary evaporation to obtain compound I-6. S5. Mix compounds I-6 and I-7 with the solvent and stir at room temperature for 15-18 hours. After the reaction is complete, evaporate by rotary evaporation to obtain compound I.

6. The preparation method according to claim 5, characterized in that, In step S1, the molar ratio of compound I-1, compound I-2 and n-butyllithium is 2-3:1:2-3.

7. The preparation method according to claim 5, characterized in that, In step S2, the molar ratio of compound I-3, sodium hydride, and iodomethane is 1:2-5:2-5.

8. The preparation method according to claim 5, characterized in that, In step S3, the molar ratio of compound I-4, Ni(cod)2 and 2,2'-bipyridine is 1:1 to 2:1 to 2, and the molar ratio of intermediate and H2SnCl4 is 1:3 to 100.

9. The preparation method according to claim 5, characterized in that, In step S4, the molar ratio of compound I-5 to BBr3 is 1:3 to 100; In step S5, the molar ratio of compound I-6 to compound I-7 is 2:3 to 5.

10. The application of covalent molecular nanotubes as described in any one of claims 1-4 in gas separation and storage.

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