Method for observing aggregation state of molecules

Abstract

The invention discloses a method for observing the aggregation state of molecules. Specifically, the invention discloses a method for observing the molecular aggregation state by using a covalent organic framework, and the method is characterized in that the covalent organic framework is COF-300. According to the invention, the dynamic COF-300 is used as a host framework, the organic molecule is used as an object, the structure of the dynamic COF-300 and the aggregation state structure in a nanometer confinement space are analyzed from an atomic scale by using a single crystal X-ray diffraction technology, and further crystallization is not needed.

Description

Technical Field

[0001] This invention relates to a method for observing molecular aggregate states. Background Technology

[0002] Dynamic covalent organic frameworks (COFs) are three-dimensional porous crystalline materials constructed from freely rotating covalent bonds. They exhibit reversible structural transformations while maintaining a good crystalline state after the exchange or removal of guest molecules. Three-dimensional dynamic COFs are a novel type of flexible porous crystalline material. Compared to crystalline sponges, dynamic COFs, linked by covalent bonds, possess higher thermal stability. Unlike coordination alignment (CAL), where guest molecules form coordinate bonds with metal-organic frameworks, guest molecules in dynamic COFs are assembled in a dynamic nanoscale confined space primarily through host-guest interactions and guest-guest interactions. Compared to crystalline complexes crystallized through eutectic methods, dynamic COFs can be directly used for the determination of gaseous and liquid molecules without further crystallization.

[0003] Dynamic COFs, by utilizing guest-guest interactions within a dynamically confined space, hold the potential to reveal the condensed structures of organic liquids, which are typically dynamic and complex. While several COF single-crystal structures have been reported, the use of dynamic COF single crystals to resolve guest aggregation states within nanoscale confined spaces remains rare. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a novel method for observing molecular aggregate states, addressing the deficiency of insufficient types of existing methods for observing molecular aggregate states.

[0005] In this invention, we utilize a dynamic COF as the host framework and organic molecules as guests. Single-crystal X-ray diffraction is used to resolve their structures at the atomic level and their aggregated states within nanoscale confinement spaces. Nanoscale confinement spaces of different shapes and sizes adapt to different types of organic molecules, resulting in different assembly patterns. We call this method the molecular sponge strategy. This proposed dynamic crystallizable molecular sponge strategy can be used to study liquid condensed matter, reducing the challenges of liquid crystallization and providing a new research platform for molecular sponges.

[0006] The present invention solves the above-mentioned technical problems through technical solutions.

[0007] This invention provides a method for observing molecular aggregation states using a covalent organic framework, characterized in that the covalent organic framework is COF-300.

[0008] In one embodiment of the present invention, the COF-300 is a prismatic crystal.

[0009] In one aspect of the present invention, the size of the COF-300 is 9 to 50 μm, for example 10 to 50 μm, preferably 50 μm, and the size is the length of the crystal along the c-axis.

[0010] In one embodiment of the present invention, the COF-300 is a single crystal.

[0011] In one embodiment of the present invention, the COF-300 is a single crystal, and its diffraction resolution in the reciprocal space b* direction hk0 is [missing information]. For example

[0012] In one embodiment of the present invention, the full width at half maximum (FWHM) of the PXRD spectrum of the COF-300 is 0.08° to 0.2°, for example, 0.094° to 0.123°, preferably 0.123°; more preferably, the PXRD spectrum is obtained under the following test conditions: the test wavelength is a copper target. The scanning angle is 5-35°, the test step is 0.02°, and the test time is 0.5 seconds.

[0013] In one embodiment of the present invention, the full width at half maximum (FWHM) of the solid-state carbon NMR spectrum of the COF-300 is 0.5ppm to 0.7ppm, for example, 0.52ppm to 0.63ppm, preferably 0.52ppm. More preferably, the solid-state carbon NMR spectrum is obtained under the following test conditions: the test method is cross-polarized CP, the test conditions are 298K, the rotation speed is 10000 rpm, and the relaxation time is 0.3s.

[0014] In one embodiment of the present invention, the COF-300 is a prismatic single crystal with a size of 50 μm, where the size refers to the length along the c-axis of the crystal, and its diffraction resolution along the b* direction in reciprocal space is [missing information]. The PXRD spectrum has a full width at half maximum (FWHM) of 0.123°, and the solid-state carbon NMR spectrum has a FWHM of 0.52 ppm. The PXRD spectrum was obtained under the following testing conditions: the test wavelength was a copper target. The scanning angle is 5-35°, the test step is 0.02°, and the test time is 0.5 seconds. The solid-state NMR carbon spectrum is obtained under the following test conditions: the test method is cross-polarized CP, the test conditions are 298K, the rotation speed is 10000 rpm, and the relaxation time is 0.3s.

[0015] In one embodiment of the present invention, the COF-300 is prepared by the following method, which includes the following steps:

[0016] The compound shown in formula (I) COF-300 was prepared by imine exchange reaction with tetra-(p-aminophenyl)-methane via gradient diffusion.

[0017] In one embodiment of the present invention, in the imine exchange reaction, the molar ratio of the compound represented by formula (I) to tetra-(p-aminophenyl)-methane is (1-3):1, for example 1.7:1.

[0018] In one embodiment of the present invention, the imine exchange reaction is catalyzed by an organic acid, such as a C1-C6 alkyl-COOH, preferably acetic acid; the molar ratio of the organic acid to the tetra-(p-aminophenyl)-methane is (0.5-30):1, for example (2.3-23):1.

[0019] In one embodiment of the present invention, in the imine exchange reaction, a solution of tetra-(p-aminophenyl)-methane is added to a suspension of the compound shown in formula (I), and after standing for 5 to 10 days, COF-300 is prepared. The solvent of the tetra-(p-aminophenyl)-methane solution is a cyclic ether solvent, and the solvent of the suspension of the compound shown in formula (I) is a mixed solvent of cyclic ether solvent and water.

[0020] Preferably, the term "add" refers to "add drop by drop";

[0021] Preferably, the "5-10 days of standing" refers to "6 days of standing".

[0022] Preferably, the cyclic ether solvent is 1,4-dioxane;

[0023] Preferably, the purity of the cyclic ether solvent is 99.5% or higher;

[0024] Preferably, in the mixed solvent of the cyclic ether solvent and water, the volume ratio of the cyclic ether solvent to water is (2-3):1, for example 2.6:1;

[0025] Preferably, the volume ratio of the solvent in the solution of tetra-(p-aminophenyl)-methane to the solvent in the suspension of the compound as shown in formula (I) is 1:(1-2), for example 1:1.4.

[0026] Preferably, in the solution of tetra-(p-aminophenyl)-methane, the molar concentration of tetra-(p-aminophenyl)-methane is 0.05 to 0.15 mol / L, for example, 0.1 mol / L.

[0027] In one embodiment of the present invention, in the imine exchange reaction, a solution of tetra-(p-aminophenyl)-methane is added to a suspension of the compound shown in formula (I), and the mixture is heated at 60-70°C for 4-6 days to prepare COF-300. The solvent of the tetra-(p-aminophenyl)-methane solution is a cyclic ether solvent, and the solvent of the suspension of the compound shown in formula (I) is a cyclic ether solvent.

[0028] Preferably, "under conditions of 60-70°C" means "under conditions of 65°C";

[0029] Preferably, the "heating for 4-6 days" is "heating for 5 days";

[0030] Preferably, the cyclic ether solvent is 1,4-dioxane;

[0031] Preferably, the purity of the cyclic ether solvent is 99.5% or higher;

[0032] Preferably, the volume ratio of the solvent in the solution of tetra-(p-aminophenyl)-methane to the solvent in the suspension of the compound as shown in formula (I) is (3-7):1, for example 5:1;

[0033] Preferably, in the solution of tetra-(p-aminophenyl)-methane, the molar concentration of tetra-(p-aminophenyl)-methane is 0.05 to 0.15 mol / L, for example 0.05 mol / L.

[0034] In one embodiment of the present invention, the preparation method of COF-300 further includes the following steps: in a solvent, in the presence of an acid, phenylenedialdehyde and aniline undergo an imine condensation reaction to prepare a compound as shown in formula (I);

[0035] Preferably, in the imine condensation reaction, the solvent is a cyclic ether solvent and / or water, such as 1,4-dioxane and / or water; when the solvent is a cyclic ether solvent and water, the volume ratio of the cyclic ether solvent to water is (2-3):1, for example 2.6:1; preferably, the purity of the cyclic ether solvent is 99.5% or higher.

[0036] Preferably, in the imine condensation reaction, the acid is an organic acid, such as a C1-C6 alkyl-COOH, preferably acetic acid;

[0037] Preferably, in the imine condensation reaction, the molar ratio of terephthalaldehyde to aniline is 1:(2-20), for example 1:(4.5-15);

[0038] Preferably, in the imine condensation reaction, the molar ratio of the terephthalaldehyde to the acid is 1:(1-15), for example 1:(1.3-13).

[0039] Preferably, in the imine condensation reaction, the molar concentration of terephthalaldehyde in the solvent is 0.01 to 0.2 mol / L, for example, 0.02 to 0.13 mol / L.

[0040] In one aspect of this invention, the preparation method of COF-300 specifically includes the following steps:

[0041] S1: Add aniline and an aqueous solution of acetic acid to a solution of terephthalaldehyde to obtain a suspension;

[0042] S2: Add a solution of tetra-(p-aminophenyl)-methane dropwise to the suspension obtained in step S1 above to form layers, let stand, and prepare COF-300;

[0043] In step S1, the solvent of the terephthalaldehyde solution is 1,4-dioxane; the molar concentration of terephthalaldehyde in the terephthalaldehyde solution is 0.15–0.20 mol / L, for example, 0.18 mol / L; the molar ratio of terephthalaldehyde to aniline is 1:(10–20), for example, 1:15; the molar concentration of acetic acid in the aqueous acetic acid solution is 5–7 mol / L, for example, 6 mol / L; the volume ratio of 1,4-dioxane to the aqueous acetic acid solution is (2–3):1, for example, 2.5:1.

[0044] In step S2, the solvent of the tetra-(p-aminophenyl)-methane solution is 1,4-dioxane; the molar ratio of tetra-(p-aminophenyl)-methane to terephthalaldehyde is 1:(1.5-2), for example 1:1.7; the molar concentration of tetra-(p-aminophenyl)-methane in the tetra-(p-aminophenyl)-methane solution is 0.08-0.12 mol / L, for example 0.1 mol / L;

[0045] Steps S1 and S2 are performed at 20–35°C, for example, 26°C.

[0046] Preferably, steps S1 and S2 are performed in a glass diffusion tube.

[0047] In one aspect of this invention, the preparation method of COF-300 specifically includes the following steps:

[0048] I: Aniline and acetic acid are added to a solution of terephthalaldehyde and reacted to obtain mixture 1;

[0049] II: Add a solution of tetra-(p-aminophenyl)-methane to the mixture 1 obtained in step I above, and heat at 60-70°C (e.g., 65°C) for 4-6 days (e.g., 5 days) to prepare COF-300.

[0050] In step I, the solvent for the terephthalaldehyde solution is 1,4-dioxane with a purity of 99.5% or higher; the molar concentration of terephthalaldehyde in the terephthalaldehyde solution is 0.4–0.5 mol / L, for example, 0.45 mol / L; the molar ratio of terephthalaldehyde to aniline is 1:(4–5), for example, 1:4.5; the molar ratio of acetic acid to terephthalaldehyde is (10–15):1, for example, 13:1.

[0051] In step II, the solvent for the tetra-(p-aminophenyl)-methane solution is 1,4-dioxane with a purity of 99.5% or higher; the molar ratio of tetra-(p-aminophenyl)-methane to terephthalaldehyde is 1:(1.5-2), for example, 1:1.7; and the molar concentration of tetra-(p-aminophenyl)-methane in the tetra-(p-aminophenyl)-methane solution is 0.04-0.06 mol / L, for example, 0.05 mol / L.

[0052] In one aspect of this invention, the molecule is a liquid or gas molecule.

[0053] In one aspect of the present invention, the molecule is an alkane substituted with one or more OH radicals, or an alkane substituted with one or more R radicals. 1 Replacement C6-C 10 Aromatic rings, aryl alcohols, R 2 C(=O)OR 3 Or by one or more R 1 An alkyl-substituted 5-10 membered heteroaromatic ring, wherein the heteroatom is selected from one or more of N, O, and S, and the number of heteroatoms is 1, 2, or 3. 1 R is a C1-C6 alkyl group substituted with OH or one or more OH groups. 2 and R 3 It is independently a C1-C6 alkyl or a C1-C6 alkyl substituted with one or more OH groups.

[0054] In one embodiment of the present invention, the molecule is 1-butanol, 1-pentanol, 1-hexanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-pentanol, benzyl alcohol, phenol, ethyl acetate, 2-methylfuran, ethyl lactate, or ethylene glycol.

[0055] In one aspect of the present invention, in the method for observing molecular aggregation states using a covalent organic framework, the molecular aggregation states in COF-300 are analyzed by single-crystal X-ray diffraction (SXRD), wherein the COF-300 adsorbs the molecules;

[0056] Preferably, the COF-300 adsorbs the molecules by molecular vapor adsorption or molecular liquid immersion.

[0057] In one aspect of the present invention, in the method for observing the molecular aggregation state using a covalent organic framework, the COF-300 needs to be activated before adsorbing molecules;

[0058] The activation method is a conventional covalent organic framework activation method in the art. Preferably, the activation method includes the following steps: placing the COF-300 in an adsorption tube, evacuating to <500 mTorr at 20-30°C (e.g., 25°C), then raising the temperature by 5-15°C (e.g., 10°C) every 10-20 min (e.g., 15 min) to 110-130°C (e.g., 120°C), and activating at this temperature for 5-24 h (e.g., 12 h). The final vacuum degree in the sample tube should be maintained at <15 mTorr to obtain a framework with completely removed guest molecules.

[0059] In one aspect of the present invention, the method for observing molecular aggregation states using a covalent organic framework includes the following steps:

[0060] The activated COF-300 is mixed with the molecular liquid and allowed to stand at 20–35°C (e.g., 26°C) for 5–24 hours (e.g., 12 hours); or the activated COF-300 is fumigated with the molecular vapor at 30–150°C (40–120°C) for 10–15 hours (e.g., 12 hours) to obtain COF-300 adsorbing the molecules. The obtained COF-300 is subjected to SXRD testing to determine the aggregate state 1 of the molecules.

[0061] Preferably, COF-300 in aggregate state 1 is purged under N2 at 80-120 mL / min (e.g., 100 mL / min) for 2-5 h, and further SXRD tests are performed to determine the aggregate state 2 of the molecule.

[0062] Preferably, the activated COF-300 reacts with the molecular liquid or molecular vapor in an atmosphere of inert gas or air, such as nitrogen.

[0063] In one aspect of this invention, the molecular aggregation state is observed using a covalent organic framework, yielding the following molecular aggregation states:

[0064] 1-Butanol exhibits two molecular aggregate states: 1) fishbone-like aggregate and 2) linear aggregate.

[0065] 1-Pentanol has two molecular aggregate states: 1) a triple helix chain and 2) linear and S-type aggregates.

[0066] The molecular aggregate state 1 of 1-hexanol is a triple helix chain;

[0067] The molecular aggregate state 1 of 2-methyl-butanol is a triple helix chain;

[0068] The molecular aggregate state 1 of 3-methyl-butanol is a triple helix chain;

[0069] The molecular aggregate state 1 of 2-methylpentanol is a triple helix chain;

[0070] The molecular aggregate state 1 of benzyl alcohol is a triple helix chain;

[0071] The molecular aggregate state 1 of phenol is windmill-shaped;

[0072] The molecular aggregate of ethyl acetate is in a windmill-like state.

[0073] The molecular aggregate 1 of 2-methylfuran is windmill-shaped;

[0074] Ethyl lactate has a triple helix structure as its molecular aggregate.

[0075] The molecular aggregate state 1 of ethylene glycol is a double helix chain.

[0076] The present invention also provides a method for inducing molecules to form a specific aggregation state, wherein the molecules and the corresponding specific aggregation states are as follows:

[0077] 1-Butanol exhibits two molecular aggregate states: 1) fishbone-like aggregate and 2) linear aggregate.

[0078] 1-Pentanol has two molecular aggregate states: 1) a triple helix chain and 2) linear and S-type aggregates.

[0079] The molecular aggregate state 1 of 1-hexanol is a triple helix chain;

[0080] The molecular aggregate state 1 of 2-methyl-butanol is a triple helix chain;

[0081] The molecular aggregate state 1 of 3-methyl-butanol is a triple helix chain;

[0082] The molecular aggregate state 1 of 2-methylpentanol is a triple helix chain;

[0083] The molecular aggregate state 1 of benzyl alcohol is a triple helix chain;

[0084] The molecular aggregate state 1 of phenol is windmill-shaped;

[0085] The molecular aggregate of ethyl acetate is in a windmill-like state.

[0086] The molecular aggregate 1 of 2-methylfuran is windmill-shaped;

[0087] Ethyl lactate has a triple helix structure as its molecular aggregate.

[0088] The molecular aggregate state 1 of ethylene glycol is a double helix chain;

[0089] The method is characterized by mixing the activated COF-300 with the molecular liquid and allowing it to stand at 20-35°C (e.g., 26°C) for 5-24 hours (e.g., 12 hours); or by fumigating the activated COF-300 with the molecular vapor at 30-150°C (40-120°C) for 10-15 hours (e.g., 12 hours) to obtain COF-300 adsorbing the molecules, thereby obtaining the aggregated state 1 of the molecules;

[0090] COF-300 in aggregate state 1 was purged under N2 at a rate of 80–120 mL / min (e.g., 100 mL / min) for 2–5 h to obtain aggregate state 2 of the molecules.

[0091] The COF-300 mentioned is the COF-300 described in any embodiment of the present invention.

[0092] Preferably, the activation method is as described in any embodiment of the present invention.

[0093] Preferably, the activated COF-300 reacts with the molecular liquid or molecular vapor in an atmosphere of inert gas or air, such as nitrogen.

[0094] This invention also provides a method for inducing COF-300 to form specific channels, wherein the specific channels are divided into two types:

[0095] Case 1: The channel is a rhomboid channel, and the dimensions of the channel are...

[0096] Case 2: The channel has two sizes simultaneously, namely and

[0097] The method is characterized in that, when the specific channel is as described in Case 1, the method comprises the following steps: mixing the activated COF-300 with a molecular liquid and allowing it to stand at 20–35°C (e.g., 26°C) for 5–24 hours (e.g., 12 hours); or fumigating the activated COF-300 with molecular vapor at 30–150°C (40–120°C) for 10–15 hours (e.g., 12 hours).

[0098] When the specific pore is as described in case 2, the method includes the following steps: mixing the activated COF-300 with a molecular liquid and letting it stand at 20–35°C (e.g., 26°C) for 5–24 hours (e.g., 12 hours), or fumigating the activated COF-300 with molecular vapor at 30–150°C (40–120°C) for 10–15 hours (e.g., 12 hours); then purging with N2 at 80–120 mL / min (e.g., 100 mL / min) for 2–5 hours;

[0099] The molecule is the molecule described in any embodiment of the present invention, preferably 1-butanol; the COF-300 is the COF-300 described in any embodiment of the present invention.

[0100] Preferably, the activation method is as described in any embodiment of the present invention.

[0101] Preferably, the activated COF-300 reacts with the molecular liquid or molecular vapor in an atmosphere of inert gas or air, such as nitrogen.

[0102] The present invention also provides a method for quantifying the molecules adsorbed by COF-300, characterized in that the conformation of COF-300 after adsorbing different numbers of molecules is identified, a correspondence between the conformation of COF-300 and the number of molecules is constructed, and based on this correspondence, the number of molecules adsorbed by COF-300 is identified by the conformation of COF-300 after adsorbing molecules.

[0103] The COF-300 mentioned herein is the COF-300 described in any embodiment of the present invention; the molecule mentioned herein is the molecule described in any embodiment of the present invention.

[0104] Preferably, the conformation is obtained by PXRD or SXRD.

[0105] In one embodiment of the present invention, the molecule is 1-butanol.

[0106] In one embodiment of the present invention, the molecule is 1-butanol. When the molar ratio of COF-300 to the adsorbed 1-butanol is 1 mol / 2 mol, the conformation of COF-300 simultaneously has the following two sets of torsion angles: Set 1: ω torsion angle is 0.5°, ψ torsion angle is 163.2°; Set 2: ω torsion angle is 134.8°, ψ torsion angle is 176.9°. When the molar ratio of COF-300 to the adsorbed 1-butanol is 1 mol / 4 mol, the conformation of COF-300 has the following two sets of torsion angles: ω torsion angle is 180.0°, ψ torsion angle is 178.7°.

[0107] The present invention also provides a method for preparing COF-300, which is as described in any of the above-described methods for preparing COF-300.

[0108] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0109] The reagents and raw materials used in this invention are all commercially available.

[0110] The positive and progressive effects of this invention are as follows: This invention uses dynamic COF-300 as the main framework and organic molecules as guests, and uses single-crystal X-ray diffraction technology to analyze its structure at the atomic level and its aggregated state structure in the nano-confined space, without the need for further crystallization. Attached Figure Description

[0111] Figure 1 Mechanism of COF-300 single crystal growth by gradient diffusion control method (a) and optical microscope image of single crystal (b).

[0112] Figure 2 This is a single-crystal diffraction pattern of the COF-300-DC crystal in the reciprocal space b* direction (h0l).

[0113] Figure 3 SEM images of COF-300 with uniform size and morphology of 10 μm grown by vial evaporation method.

[0114] Figure 4 The particle size distribution is COF-300-10μm.

[0115] Figure 5 PXRD patterns of COF-300-DC and COF-300-10μm.

[0116] Figure 6 For COF-300-DC and COF-300-10μm 13 C ss NMR spectrum.

[0117] Figure 7 The 298K butanol isotherm adsorption curves are for COF-300-DC and COF-300-10μm.

[0118] Figure 8 The adsorption heat curve for COF-300-10μm is shown.

[0119] Figure 9 Diagrams of in-situ vapor adsorption-PXRD and semi-in-situ vapor adsorption-SXRD test setups.

[0120] Figure 10 The in-situ PXRD patterns of COF-300-10μm vapor adsorption under different partial pressures are shown.

[0121] Figure 11 The equilibrium PXRD patterns of COF-300-10μm at partial pressures of 30%, 35%, 40%, 50%, and 90% 1-butanol are shown.

[0122] Figure 12 Define the degrees of freedom in the COF-300 segment.

[0123] Figure 13 The potential distribution diagram shows the different conformations of COF-300.

[0124] Figure 14 Nanoscale confinement spaces for different conformations of COF-300.

[0125] Figure 15 This represents the aggregated state of 1-butanol molecules in the ip and op structures.

[0126] Figure 16 This represents the aggregated state of 1-pentanol molecules in the ip and op structures.

[0127] Figure 17 This represents the aggregated state of 1-hexanol molecules in the op structure.

[0128] Figure 18 This represents the aggregated state of 2-methyl-butanol molecules in the op structure.

[0129] Figure 19 This represents the aggregated state of 3-methyl-butanol molecules in the op structure.

[0130] Figure 20 This represents the aggregated state of 2-pentanol molecules in the op structure.

[0131] Figure 21 This represents the aggregated state of benzyl alcohol molecules in the op structure.

[0132] Figure 22 This represents the aggregated state of phenol molecules in the op structure.

[0133] Figure 23 This represents the aggregated state of ethyl acetate molecules in the op structure.

[0134] Figure 24 It represents the aggregated state of 2-methylfuran in the op structure.

[0135] Figure 25 This represents the aggregated state of ethyl lactate in the op structure.

[0136] Figure 26 This represents the aggregated state of ethylene glycol in the op structure. Detailed Implementation

[0137] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0138] Those skilled in the art will understand that the numerical values ​​or ranges described in the embodiments include a reasonable range of deviations caused by fluctuations in conventional testing conditions (such as system errors of measuring equipment, changes in ambient temperature and humidity, fluctuations in raw material purity, etc.).

[0139] Any technical solution based on the inventive concept and implemented through equivalent substitution or obvious modification, if its technical effect is substantially equivalent to the embodiments of the present invention, shall fall within the scope of the claims.

[0140] Example 1: Synthesis of Single Crystals using COF-300-DC (Gradient Diffusion Method)

[0141] Terephthalaldehyde (TPA, 12.0 mg, 0.089 mmol) was dissolved in 1,4-dioxane (0.5 mL), and aniline (0.12 mL, 15 equivalents) and an aqueous solution of acetic acid (AcOH; 6 mol / L) were added. -1 White flake crystals precipitated from the bottom of a vertically placed glass diffusion tube (inner diameter ~4.24 mm) after being dissolved in 0.2 mL of 1,4-dioxane (0.5 mL) in tetra-(p-aminophenyl)-methane (TAM, 20.0 mg, 0.052 mmol) dropwise to form a layer. A diffusion gradient transfer scheme controlled nucleation and crystal growth, producing COF-300 prismatic crystals with a size of approximately 50 μm (50 μm refers to length, represented by the c-axis direction on the crystal) within 6 days. A schematic diagram of the preparation and structural characterization are shown below. Figure 1 and Figure 2 The above process is carried out at room temperature (determined according to the laboratory temperature, for example, 26°C).

[0142] A schematic diagram of the COF-300-DC fabrication process is shown below. Figure 1 (a).

[0143] Optical microscope images were taken of the samples prepared in the glass diffusion tube using a Leica optical microscope at 50x magnification. Figure 1 (b) shows that the crystal size is about 50 μm.

[0144] Single-crystal X-ray diffraction (SXRD) analysis of the aqueous phase of COF-300 showed that the diffraction resolution in the reciprocal lattice space b* direction hk0 reached [value missing]. ( Figure 2The diffraction resolution of hk0 was determined using APEX4 software, which integrated all tested diffraction points and extracted the hk0 diffraction pattern. SXRD data were measured at the BL17B beamline of the Shanghai Synchrotron Radiation Facility (SSRF) at an energy of 18 keV. The beamline was equipped with a Decrispilatus 3-2M detector, and the collection temperature was 100 K. Data reconstruction and integration were performed using Apex4 software, and data correction was performed using standard SADABS correction without attenuation correction. The single-crystal structure was determined using SHELXT's Intrinsic Phasing direct method. The structure of the synthesized sample can be obtained from... Figure 14 The crystal structure was confirmed to be COF-300.

[0145] Figure 5 The PXRD spectrum of the COF-300-DC micrometer showed a full width at half maximum (FWHM) of 0.123°. The testing instrument was a Bruker D8 Advance, with an operating voltage of 40 kV and an operating current of 40 mA. The test wavelength was measured using a copper target. The scanning angle was 5-35°, the test step size was 0.02°, and the test time was 0.5 seconds. Standard PXRD spectra were generated using single-crystal data with Cambridge Analytica's Mercury software, and FWMH was measured using Java software. The PXRD spectra showed that the synthesized sample's theoretical Bragg diffraction pattern was consistent with that generated from COF-300 single-crystal data simulation.

[0146] Figure 6 The full width at half maximum (FWHM) of the solid-state carbon NMR spectrum of the COF-300-DC is 0.52 ppm, which is consistent with... Figure 5 Together, these methods can characterize the sample's good crystalline state. The solid-state carbon NMR spectrometer was a Bruker ADVANCEIIIHD 400MHz solid NMR spectrometer, and the test method was cross-polarized CP. The test conditions were room temperature, rotation speed of 10,000 rpm, relaxation time of 0.3 s, and FWHM was measured using TopSpin software.

[0147] Example 2: Synthesis of Uniform-Sized COF-300 Crystals

[0148] To optimize adsorption kinetics and achieve synergistic structural transformation, a vial evaporation method was developed to obtain COF-300 samples with uniform size and morphology, denoted as COF-300-10μm. The specific procedure is as follows:

[0149] TPA (60.0 mg, 0.445 mmol) was dissolved in 1,4-dioxane (1 mL) in a 20 mL glass bottle. Aniline (0.20 mL) and AcOH (6 mol / L) were then added to the solution. -11 mL). Then, the solution of 1,4-dioxane (5 mL) containing dissolved TAM (100.0 mg, 0.26 mmol) was added to the vial and heated at 65 °C for 5 days. COF-300 crystals with a size of 10 μm were obtained and thoroughly extracted with 1,4-dioxane and tetrahydrofuran at 145 °C and 85 °C, respectively (using Soxhlet extraction to thoroughly wash away impurities). The crystal size and morphology were observed under a scanning electron microscope; see details below. Figure 3 .

[0150] Figure 3 The SEM images show that the crystals have a spindle-shaped morphology with uniform size. The SEM instrument used was a JSM-7800, with an operating voltage of 2kV, an operating current of 6mA, and a vacuum level of 4 x 10⁻⁶. -5 Pa.

[0151] The crystals in the SEM images were measured using Nano_Measurer software, and their size was plotted to obtain a particle size distribution map. Figure 4 The size range is 9-10μm, and for convenience, it is denoted as COF-300-10μm.

[0152] PXRD patterns and solid-state carbon NMR spectra ( Figure 5 The half-maximum widths (WHM) of the synthesized sample (6) were 0.094° and 0.63 ppm, indicating good crystallinity. The PXRD pattern showed that the synthesized sample was consistent with the theoretical Bragg diffraction pattern generated by simulation using COF-300 single-crystal data. The PXRD pattern and solid-state carbon NMR spectroscopy were performed under the same conditions as in Example 1.

[0153] Example 3: Comparison of adsorption behavior of COF-300-DC and COF-300-10μm

[0154] Before performing the 1-butanol vapor adsorption test, the sample was activated: the COF-300 sample was transferred to a 9 mm adsorption tube and connected to a Quantachrome Flovac vacuum degassing station in the United States. First, the sample was evacuated at 25°C for 2-3 hours until the vacuum level dropped to <500 mTorr. Then, the temperature was increased by 10°C every 15 minutes in stages until it reached 120°C overnight for activation. The final vacuum level in the sample tube should be maintained at <15 mTorr to obtain a framework in which guest molecules were completely removed. After cooling to 25°C and backfilling with pure nitrogen, the sample could be transferred to the next step of gas adsorption testing.

[0155] (1) Comparison of butanol adsorption curves of COF-300-DC and COF-300-10μm

[0156] Figure 7The adsorption isotherm curves of 1-butanol at 298 K were obtained by testing the 298 K adsorption-desorption isotherms of the samples using a static adsorption instrument (Bruker MAXⅡ). ​​The adsorption responses of COF-300-DC and COF-300-10μm samples to butanol were basically the same. The sample mass was 50-100 mg for each test, and P0 was manually input as 1.30 kPa during the test.

[0157] (2) Test of system heat change during COF-300-10μm adsorption of butanol

[0158] Figure 8 The display shows the heat change of the COF-300-10μm system during the adsorption of butanol, tested at 298K. The heat of adsorption was obtained using an adsorption-calorimetry (AC) system with a KEP ChemStar instrument. The heat change was obtained by integrating the heat flow signal measured by the calorimeter, and the heat was divided by the amount of adsorption under the test conditions to obtain the heat of adsorption value. The results show that the heat of adsorption of COF-300-10μm during the adsorption of butanol is above 65 kJ / mol, exhibiting both host-guest and guest-guest interactions. Figure 8 Activation conditions during testing and Figure 7 The only difference is that the sample tube is a U-shaped tube, the sample mass is about 50mg, and the P0 is manually input as 1.30kPa during the test.

[0159] (3) Conformational changes during the butanol adsorption and desorption processes of COF-300-DC and COF-300-10μm

[0160] Figure 9 For the dynamic vapor adsorption testing device: the working gas concentration of the organic vapor is achieved by mixing saturated nitrogen vapor and dry N2 from the solvent storage tank, with the ratio controlled using two 100 sccm flow controllers. In this invention patent, only 1-butanol is used as the probe molecule for in-situ PXRD testing. This working gas is introduced onto the XRK-900 in-situ testing sample stage of the powder X-ray diffractometer, or onto the capillary of a single crystal sample.

[0161] Due to the size effect of COF-300, the diffusion rate of vapor in the pores slows down when the size is too large; size inhomogeneity makes it difficult for phase transitions in the structure to be coordinated. Therefore, in-situ vapor-PXRD tests using COF-300-10μm samples are used to macroscopically examine the number of possible conformations of COF-300.

[0162] Figure 10The images show in-situ PXRD patterns of COF-300-10μm vapor adsorption under different partial pressures. Red represents the adsorption process, and blue represents the desorption process. PXRD patterns were continuously collected at a stable vapor concentration until the positions and intensities of the PXRD diffraction peaks reached equilibrium. The testing conditions were then adjusted to the next set point. During adsorption, at a relative vapor pressure of 25%, and when 1 mol / mol (the number of 1-butanol molecules in the smallest asymmetric unit of a single crystal) of vapor molecules were adsorbed, the PXRD diffraction peaks at 8.73°, 17.48°, 20.56°, and 24.13° began to shift. Figure 10 The areas circled in red in the diagram show the structure transitioning from a contractile phase (cp) to an intermediate phase (ip) conformation when adsorbing 2 mol / mol of vapor molecules at a relative humidity of 40%. At a relative humidity of 90%, the structure completely transforms into an open phase (op) conformation when adsorbing 4 mol / mol of vapor molecules. During desorption, under dry nitrogen purging at room temperature, the structure is a miscible phase of op and ip; heating to 120℃ causes a reversible transformation back to the cp conformation. The in-situ PXRD structural transformation is consistent with the dynamic behavior of vapor adsorption. Figure 7 ).

[0163] Figure 11 The values ​​are the equilibrium PXRD spectra of COF-300-10μm at partial pressures of 30%, 35%, 40%, 50%, and 90% 1-butanol, compared with the simulated PXRD spectra of the COF-300-cp, -ip, and -op structures obtained from COF-300-DC measurements. Figure 1 The method for simulating PXRD spectra is consistent with that in Example 1. Figure 5 The methods used are the same.

[0164] Example 4: Testing Molecular Aggregate State Using COF-300-DC

[0165] 1-Butanol adsorption-in-situ PXRD testing revealed that COF-300 has three conformations. The structural changes were difficult to accurately determine using Rietveld refinement. Therefore, single-crystal X-ray diffraction was used with COF-300-DC to determine and resolve the structures of different conformations at the atomic level.

[0166] Figure 13 , 14Sample preparation for SXRD testing of 1-butanol-induced structural changes and guest assembly in section 16: When butanol is used as the probe molecule, for the cp phase: after activation, the sample was placed in a glass capillary with an inner diameter of approximately 50 micrometers in a nitrogen glove box, and SXRD testing was performed at the Shanghai Synchrotron Radiation Facility (SSRF) at an energy of 18 keV; for the op phase: the activated phase sample was immersed in butanol solution and left overnight at room temperature before testing at the SSRF at an energy of 18 keV; for the ip phase: the open phase sample was placed in a capillary with an inner diameter of 0.4 mm, purged with nitrogen at 100 mL / min for 2-3 hours, and tested at the BL10U2 beamline of the SSRF at an energy of 18 keV. The beamline was equipped with a Decris Eiger 16M, S / N E-32-0111 detector, and the collection temperature was 100 K. Data restoration and integration were performed using Apex4 software, and data correction was performed using standard SADABS correction without attenuation correction. The single crystal structure was obtained using SHELXT's Intrinsic Phasing direct method. All non-hydrogen atoms were obtained using the difference Fourier correction method. Anisotropic refinement was performed, and isotropic refinement was performed after rigid confinement of hydrogen atoms. The benzene ring was also rigidly confined.

[0167] Figure 12 Define the ω degree of freedom in the COF-300 structural segment. Figure 13 The potential distribution map of the main framework is shown. The structure was obtained through SXRD analysis using Olex software. The potential distribution map of the main framework demonstrates the high resolution and accuracy of the test results, revealing at the atomic level the metastable phase (ip phase) of the dynamic COF during structural evolution, from the cp phase to the op phase. The twist angle of the diimine group (ω) of terephthalic acid was also determined, showing the conformational changes from trans-coplanar (180°) to cis-coplanar (0.5°) / ortho-staggered (134.8°), and then back to trans-coplanar (180°).

[0168] Figure 14 The crystal structures of different conformations in SXRD testing are shown below, along with their corresponding space group and unit cell information. Figure 13 In the ω-angle conformational transition, COF-300 exhibits four different nanoconfined spaces. The confinement spaces of the cp and op phases manifest as rhomboid channels with dimensions of [missing information]. and Due to reduced symmetry, the IP phase has two confined spaces with different shapes and sizes, with the following dimensions: and

[0169] COF-300-DC has been used to test various guest molecules, including 1-butanol, 1-pentanol, 1-hexanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-pentanol, benzyl alcohol, phenol, ethyl acetate, 2-methylfuran, ethyl lactate, and ethylene glycol. The flexible conformation of COF-300 allows it to adapt to molecules with a wide range of functional groups. Specifically, 1-pentanol can induce a reversible structural transition from the activated mesophase to the open phase in COF-300; other molecules, as currently tested, exhibit open-phase symmetry.

[0170] The obtained product was subjected to single-crystal X-ray diffraction to resolve the structure of the main framework and guest molecules, and to analyze the changes in the aggregation state of the guest in different nanoscale confinement spaces.

[0171] Figure 15 The 1-butanol molecules aggregate in the ip and op structures, exhibiting linear and herringbone-like structures, respectively. Preparation methods: op phase: The activated phase sample was immersed in a 1-butanol solution and left overnight at room temperature before testing at the Shanghai Synchrotron Radiation Facility (SSRF) at an energy of 18 keV; ip phase: The open phase sample was placed in a 0.4 mm inner diameter capillary tube, purged with nitrogen at 100 mL / min for 2-3 hours, and then tested at the SSRF using the following apparatus: Figure 4 As shown, the energy used in the test was 18keV.

[0172] Figure 16 The 1-pentanol molecule exhibits aggregated states in the ip and op structures, displaying linear and S-shaped structures in the ip phase and a triple helix chain in the op phase. Preparation methods: op phase: The activated phase sample is immersed in a 1-pentanol solution and left overnight at room temperature before testing at the Shanghai Synchrotron Radiation Facility (SSRF) at an energy of 18 keV; ip phase: The open phase sample is placed in a 0.4 mm inner diameter capillary tube, purged with nitrogen at 100 mL / min for 4-5 hours, and then tested at the SSRF using the following apparatus: Figure 4 As shown, the energy used in the test was 18keV.

[0173] Figure 17 The 1-hexanol molecule is aggregated in the op structure, exhibiting a triple helix chain. Preparation method: After fumigation at 40℃ for 12 hours, the crystal was removed and tested at the Shanghai Synchrotron Radiation Facility. Data was reduced using Apex4 and the structure was resolved using Olex2.

[0174] Figure 18 The 2-methyl-butanol molecule is aggregated in the op structure, exhibiting a triple helix chain. Preparation method: After fumigation at 40℃ for 12 hours, the crystal was removed and tested at the Shanghai Synchrotron Radiation Facility. Data was reduced using Apex4 and the structure was resolved using Olex2.

[0175] Figure 19The 3-methyl-butanol molecule is aggregated in the op structure, exhibiting a triple helix chain. Preparation method: After fumigation at 40℃ for 12 hours, the crystal was removed and tested at the Shanghai Synchrotron Radiation Facility. Data was reduced using Apex4 and the structure was resolved using Olex2.

[0176] Figure 20 The 2-methyl-pentanol molecule is aggregated in the op structure, exhibiting a triple helix chain. Preparation method: After fumigation at 40℃ for 12 hours, the crystal was removed and tested at the Shanghai Synchrotron Radiation Facility. Data was reduced using Apex4 and the structure was resolved using Olex2.

[0177] Figure 21 The benzyl alcohol molecules are aggregated in the op structure, exhibiting a triple helix chain. Preparation method: After soaking at room temperature for 12 hours, the crystals were removed and tested at the Shanghai Synchrotron Radiation Facility. Data were restored using Apex4 and the structure was resolved using Olex2.

[0178] Figure 22 The phenol molecules are aggregated in the op structure, exhibiting a windmill-like shape. Preparation method: After fumigation at 120℃ for 12 hours, the crystals were removed and tested at the Shanghai Synchrotron Radiation Facility. Data were reduced using Apex4 and the structure was resolved using Olex2.

[0179] Figure 23 The ethyl acetate molecules are aggregated in the op structure, exhibiting a windmill-like shape. Preparation method: After fumigation at 40℃ for 12 hours, the crystals were removed and tested at the Shanghai Synchrotron Radiation Facility. The structure was then resolved using Apex4 data reduction and Olex2 analysis.

[0180] Figure 24 The 2-methylfuran molecule is aggregated in the op structure, exhibiting a windmill-like shape. Preparation method: After fumigation at 40℃ for 12 hours, the crystal was removed and tested at the Shanghai Synchrotron Radiation Facility. The data was reduced using Apex4 and the structure was resolved using Olex2.

[0181] Figure 25 The ethyl lactate molecule is aggregated in the op structure, exhibiting a triple helix chain. Preparation method: After fumigation at 40℃ for 12 hours, the crystal was removed and tested at the Shanghai Synchrotron Radiation Facility. Data was restored using Apex4 and the structure was resolved using Olex2.

[0182] Figure 26 The ethylene glycol molecules are aggregated in the op structure, exhibiting a double helix chain. Preparation method: After soaking at room temperature for 12 hours, the crystals were removed and tested at the Shanghai Synchrotron Radiation Facility. Data were restored using Apex4, and the structure was resolved using Olex2.

Claims

1. A method for observing molecular aggregation states using covalent organic frameworks, characterized in that, The covalent organic framework mentioned is COF-300.

2. The method for observing molecular aggregation states using covalent organic frameworks as described in claim 1, characterized in that, It meets one or more of the following conditions: (1) The COF-300 is prismatic in shape; (2) The size of the COF-300 is 9 to 50 μm, for example 10 to 50 μm, preferably 50 μm, and the size is the length of the crystal along the c-axis. (3) The COF-300 is a single crystal; preferably, the diffraction resolution of hk0 in the reciprocal space b* direction is . For example (4) The full width at half maximum (FWHM) of the PXRD spectrum of the COF-300 is 0.08° to 0.2°, for example, 0.094° to 0.123°, preferably 0.123°; more preferably, the PXRD spectrum is obtained under the following test conditions: the test wavelength is a copper target. The scanning angle is 5-35°, the test step is 0.02°, and the test time is 0.5 seconds. (5) The full width at half maximum (FWHM) of the solid-state carbon NMR spectrum of the COF-300 is 0.5ppm to 0.7ppm, for example, 0.52ppm to 0.63ppm, preferably 0.52ppm. More preferably, the solid-state carbon NMR spectrum is obtained under the following test conditions: the test method is cross-polarized CP, the test conditions are 298K, the rotation speed is 10000 rpm, and the relaxation time is 0.3s. (6) The molecule is a liquid or gas molecule, such as an alkane substituted with one or more OH groups, or a molecule substituted with one or more R groups. 1 Replacement C6-C 10 Aromatic rings, aryl alcohols, R 2 C(=O)OR 3 Or by one or more R 1 An alkyl-substituted 5-10 membered heteroaromatic ring, wherein the heteroatom is selected from one or more of N, O, and S, and the number of heteroatoms is 1, 2, or 3. 1 R is a C1-C6 alkyl group substituted with OH or one or more OH groups. 2 and R 3 Independently, it is a C1-C6 alkyl group or a C1-C6 alkyl group substituted with one or more OH groups; further, for example, 1-butanol, 1-pentanol, 1-hexanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-pentanol, benzyl alcohol, phenol, ethyl acetate, 2-methylfuran, ethyl lactate or ethylene glycol; Preferably, the COF-300 is a prismatic single crystal with a size of 50 μm, where the size refers to the length along the c-axis of the crystal, and its hk0 diffraction resolution is [missing value]. The PXRD spectrum has a full width at half maximum (FWHM) of 0.123°, and the solid-state carbon NMR spectrum has a FWHM of 0.52 ppm. The PXRD spectrum was obtained under the following testing conditions: the test wavelength was a copper target. The scanning angle is 5-35°, the test step is 0.02°, and the test time is 0.5 seconds. The solid-state NMR carbon spectrum is obtained under the following test conditions: the test method is cross-polarized CP, the test conditions are 298K, the rotation speed is 10000 rpm, and the relaxation time is 0.3s.

3. The method for observing molecular aggregation states using covalent organic frameworks as described in claim 1, characterized in that, The COF-300 is prepared by the following method, which includes the following steps: The compound shown in formula (I) COF-300 was prepared by imine exchange reaction with tetra-(p-aminophenyl)-methane via gradient diffusion. Preferably, the method for preparing COF-300 satisfies one or more of the following conditions: (1) In the imine exchange reaction, the molar ratio of the compound shown in formula (I) to tetra-(p-aminophenyl)-methane is (1-3):1, for example 1.7:1; (2) The imine exchange reaction is catalyzed by an organic acid, such as a C1-C6 alkyl-COOH, preferably acetic acid; the molar ratio of the organic acid to the tetra-(p-aminophenyl)-methane is (0.5-30):1, for example (2.3-23):1; (3) The imine exchange reaction described herein is either Scheme 1 or Scheme 2. Scheme 1: Add a solution of tetra-(p-aminophenyl)-methane to a suspension of the compound shown in formula (I), and let it stand for 5 to 10 days to prepare COF-300. The solvent of the tetra-(p-aminophenyl)-methane solution is a cyclic ether solvent, and the solvent of the suspension of the compound shown in formula (I) is a mixed solvent of cyclic ether solvent and water. Preferably, the term "add" refers to "add drop by drop"; Preferably, the "5-10 days of standing" refers to "6 days of standing". Preferably, the cyclic ether solvent is 1,4-dioxane; Preferably, the purity of the cyclic ether solvent is 99.5% or higher; Preferably, in the mixed solvent of the cyclic ether solvent and water, the volume ratio of the cyclic ether solvent to water is (2-3):1, for example 2.6:1; Preferably, the volume ratio of the solvent in the solution of tetra-(p-aminophenyl)-methane to the solvent in the suspension of the compound as shown in formula (I) is 1:(1-2), for example 1:1.

4. Preferably, in the solution of tetra-(p-aminophenyl)-methane, the molar concentration of tetra-(p-aminophenyl)-methane is 0.05 to 0.15 mol / L, for example 0.1 mol / L; Option 2: In the imine exchange reaction, a solution of tetra-(p-aminophenyl)-methane is added to a suspension of the compound shown in formula (I), and the mixture is heated at 60-70°C for 4-6 days to prepare COF-300. The solvent of the tetra-(p-aminophenyl)-methane solution is a cyclic ether solvent, and the solvent of the suspension of the compound shown in formula (I) is a cyclic ether solvent. Preferably, "under conditions of 60-70°C" means "under conditions of 65°C"; Preferably, the "heating for 4-6 days" means "heating for 5 days"; Preferably, the cyclic ether solvent is 1,4-dioxane; Preferably, the purity of the cyclic ether solvent is 99.5% or higher; Preferably, the volume ratio of the solvent in the solution of tetra-(p-aminophenyl)-methane to the solvent in the suspension of the compound as shown in formula (I) is (3-7):1, for example 5:1; Preferably, in the solution of tetra-(p-aminophenyl)-methane, the molar concentration of tetra-(p-aminophenyl)-methane is 0.05 to 0.15 mol / L, for example 0.05 mol / L; (4) The preparation method of COF-300 further includes the following steps: in a solvent, in the presence of an acid, phenylenedialdehyde and aniline undergo an imine condensation reaction to prepare a compound as shown in formula (I); Preferably, in the imine condensation reaction, the solvent is a cyclic ether solvent and / or water, such as 1,4-dioxane and / or water; when the solvent is a cyclic ether solvent and water, the volume ratio of the cyclic ether solvent to water is (2-3):1, for example 2.6:1; preferably, the purity of the cyclic ether solvent is 99.5% or higher. Preferably, in the imine condensation reaction, the acid is an organic acid, such as a C1-C6 alkyl-COOH, preferably acetic acid; Preferably, in the imine condensation reaction, the molar ratio of terephthalaldehyde to aniline is 1:(2-20), for example 1:(4.5-15); Preferably, in the imine condensation reaction, the molar ratio of the terephthalaldehyde to the acid is 1:(1-15), for example 1:(1.3-13); Preferably, in the imine condensation reaction, the molar concentration of terephthalaldehyde in the solvent is 0.01 to 0.2 mol / L, for example, 0.02 to 0.13 mol / L.

4. The method for observing molecular aggregation states using covalent organic frameworks as described in claim 3, characterized in that, The preparation method of COF-300 specifically includes the following steps: S1: Add aniline and an aqueous solution of acetic acid to a solution of terephthalaldehyde to obtain a suspension; S2: Add a solution of tetra-(p-aminophenyl)-methane dropwise to the suspension obtained in step S1 above to form layers, let stand, and prepare COF-300; In step S1, the solvent of the terephthalaldehyde solution is 1,4-dioxane; the molar concentration of terephthalaldehyde in the terephthalaldehyde solution is 0.15–0.20 mol / L, for example, 0.18 mol / L; the molar ratio of terephthalaldehyde to aniline is 1:(10–20), for example, 1:15; the molar concentration of acetic acid in the aqueous acetic acid solution is 5–7 mol / L, for example, 6 mol / L; the volume ratio of 1,4-dioxane to the aqueous acetic acid solution is (2–3):1, for example, 2.5:

1. In step S2, the solvent of the tetra-(p-aminophenyl)-methane solution is 1,4-dioxane; the molar ratio of tetra-(p-aminophenyl)-methane to terephthalaldehyde is 1:(1.5-2), for example 1:1.7; the molar concentration of tetra-(p-aminophenyl)-methane in the tetra-(p-aminophenyl)-methane solution is 0.08-0.12 mol / L, for example 0.1 mol / L; Steps S1 and S2 are performed at 20–35°C, for example, 26°C. Preferably, steps S1 and S2 are performed in a glass diffusion tube; or, The preparation method of COF-300 specifically includes the following steps: I: Aniline and acetic acid are added to a solution of terephthalaldehyde and reacted to obtain mixture 1; II: Add a solution of tetra-(p-aminophenyl)-methane to the mixture 1 obtained in step I above, and heat at 60-70°C (e.g., 65°C) for 4-6 days (e.g., 5 days) to prepare COF-300. In step I, the solvent for the terephthalaldehyde solution is 1,4-dioxane with a purity of 99.5% or higher; the molar concentration of terephthalaldehyde in the terephthalaldehyde solution is 0.4–0.5 mol / L, for example, 0.45 mol / L; the molar ratio of terephthalaldehyde to aniline is 1:(4–5), for example, 1:4.5; the molar ratio of acetic acid to terephthalaldehyde is (10–15):1, for example, 13:

1. In step II, the solvent for the tetra-(p-aminophenyl)-methane solution is 1,4-dioxane with a purity of 99.5% or higher; the molar ratio of tetra-(p-aminophenyl)-methane to terephthalaldehyde is 1:(1.5-2), for example, 1:1.7; and the molar concentration of tetra-(p-aminophenyl)-methane in the tetra-(p-aminophenyl)-methane solution is 0.04-0.06 mol / L, for example, 0.05 mol / L.

5. The method for observing molecular aggregation states using a covalent organic framework as described in claim 1 or 2, characterized in that, The molecular aggregation state in COF-300 was analyzed by single-crystal X-ray diffraction, and the molecules were adsorbed by COF-300. Preferably, the COF-300 adsorbs the molecules by molecular vapor adsorption or molecular liquid immersion; Preferably, the COF-300 needs to be activated before adsorbing molecules. The activation method preferably includes the following steps: placing the COF-300 in an adsorption tube, evacuating to <500 mTorr at 20-30°C (e.g., 25°C), then raising the temperature by 5-15°C (e.g., 10°C) every 10-20 min (e.g., 15 min) to 110-130°C (e.g., 120°C), and activating at this temperature for 5-24 h (e.g., 12 h). The final vacuum degree in the sample tube should be maintained at <15 mTorr to obtain a framework with completely removed guest molecules.

6. The method for observing molecular aggregation states using covalent organic frameworks as described in claim 5, characterized in that, It includes the following steps: The activated COF-300 is mixed with the molecular liquid and allowed to stand at 20–35°C (e.g., 26°C) for 5–24 hours (e.g., 12 hours); or the activated COF-300 is fumigated with the molecular vapor at 30–150°C (40–120°C) for 10–15 hours (e.g., 12 hours) to obtain COF-300 adsorbing the molecules. The obtained COF-300 is subjected to SXRD testing to determine the aggregate state 1 of the molecules. Preferably, COF-300 in aggregate state 1 is purged under N2 at 80-120 mL / min (e.g., 100 mL / min) for 2-5 h, and further SXRD tests are performed to determine the aggregate state 2 of the molecule. Preferably, the activated COF-300 reacts with the molecular liquid or molecular vapor in an atmosphere of inert gas or air, such as nitrogen. Preferably, by observing the molecular aggregation state using a covalent organic framework, the following molecular aggregation states are obtained: 1-Butanol exhibits two molecular aggregate states: 1) fishbone-like aggregate and 2) linear aggregate. 1-Pentanol has two molecular aggregate states: 1) a triple helix chain and 2) linear and S-type aggregates. The molecular aggregate state 1 of 1-hexanol is a triple helix chain; The molecular aggregate state 1 of 2-methyl-butanol is a triple helix chain; The molecular aggregate state 1 of 3-methyl-butanol is a triple helix chain; The molecular aggregate state 1 of 2-methyl-pentanol is a triple helix chain; The molecular aggregate state 1 of benzyl alcohol is a triple helix chain; The molecular aggregate state 1 of phenol is windmill-shaped; The molecular aggregate of ethyl acetate is in a windmill-like state. The molecular aggregate 1 of 2-methylfuran is windmill-shaped; Ethyl lactate has a triple helix structure as its molecular aggregate. The molecular aggregate state 1 of ethylene glycol is a double helix chain.

7. A method for inducing molecules to form a specific aggregate state, wherein, The molecules and their corresponding specific aggregation states are as follows: 1-Butanol exhibits two molecular aggregate states: 1) fishbone-like aggregate and 2) linear aggregate. 1-Pentanol has two molecular aggregate states: 1) a triple helix chain and 2) linear and S-type aggregates. The molecular aggregate state 1 of 1-hexanol is a triple helix chain; The molecular aggregate state 1 of 2-methyl-butanol is a triple helix chain; The molecular aggregate state 1 of 3-methyl-butanol is a triple helix chain; The molecular aggregate state 1 of 2-methylpentanol is a triple helix chain; The molecular aggregate state 1 of benzyl alcohol is a triple helix chain; The molecular aggregate state 1 of phenol is windmill-shaped; The molecular aggregate of ethyl acetate is in a windmill-like state. The molecular aggregate 1 of 2-methylfuran is windmill-shaped; Ethyl lactate has a triple helix structure as its molecular aggregate. The molecular aggregate state 1 of ethylene glycol is a double helix chain; The method is characterized by mixing the activated COF-300 with the molecular liquid and allowing it to stand at 20-35°C (e.g., 26°C) for 5-24 hours (e.g., 12 hours); or by fumigating the activated COF-300 with the molecular vapor at 30-150°C (40-120°C) for 10-15 hours (e.g., 12 hours) to obtain COF-300 adsorbing the molecules, thereby obtaining the aggregated state 1 of the molecules; COF-300 in aggregate state 1 was purged under N2 at a rate of 80–120 mL / min (e.g., 100 mL / min) for 2–5 h to obtain aggregate state 2 of the molecules. The COF-300 mentioned above is the COF-300 as described in any one of claims 1-6; Preferably, the activation method is as described in claim 5; Preferably, the activated COF-300 reacts with the molecular liquid or molecular vapor in an atmosphere of inert gas or air, such as nitrogen.

8. A method for inducing COF-300 to form specific channels, wherein the specific channels are of two types: Case 1: The channel is a rhomboid channel, and the dimensions of the channel are... Case 2: The channel has two sizes simultaneously, namely and Its features are, When the specific pore is as described in Case 1, the method includes the following steps: mixing the activated COF-300 with a molecular liquid and letting it stand at 20–35°C (e.g., 26°C) for 5–24 hours (e.g., 12 hours); or fumigating the activated COF-300 with molecular vapor at 30–150°C (40–120°C) for 10–15 hours (e.g., 12 hours). When the specific pore is as described in case 2, the method includes the following steps: mixing the activated COF-300 with a molecular liquid and letting it stand at 20–35°C (e.g., 26°C) for 5–24 hours (e.g., 12 hours), or fumigating the activated COF-300 with molecular vapor at 30–150°C (40–120°C) for 10–15 hours (e.g., 12 hours); then purging with N2 at 80–120 mL / min (e.g., 100 mL / min) for 2–5 hours; The molecule is the molecule as described in any one of claims 1-6, preferably 1-butanol; the COF-300 is the COF-300 as described in any one of claims 1-6; Preferably, the activation method is as described in claim 5; Preferably, the activated COF-300 reacts with the molecular liquid or molecular vapor in an atmosphere of inert gas or air, such as nitrogen.

9. A method for quantifying the molecules adsorbed by COF-300, characterized in that, The conformations of COF-300 after adsorbing different numbers of molecules were identified, the correspondence between the conformations of COF-300 and the number of molecules was constructed, and based on this correspondence, the number of molecules adsorbed by COF-300 was determined by the conformations of COF-300 after adsorbing molecules. The COF-300 is the COF-300 as described in any one of claims 1-6; the molecule is the molecule as described in any one of claims 1-6; Preferably, the conformation is obtained by PXRD or SXRD; Preferably, the molecule is 1-butanol; more preferably, the molecule is 1-butanol, and when the molar ratio of COF-300 to the adsorbed 1-butanol is 1 mol / 2 mol, the conformation of COF-300 simultaneously has the following two sets of torsion angles: Group 1: ω torsion angle is 0.5°, ψ torsion angle is 163.2°; Group 2: ω torsion angle is 134.8°, ψ torsion angle is 176.9°; when the molar ratio of COF-300 to the adsorbed 1-butanol is 1 mol / 4 mol, the conformation of COF-300 has the following two sets of torsion angles: ω torsion angle is 180.0°, ψ torsion angle is 178.7°.

10. A method for preparing COF-300, as described in any one of claims 1-6.

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