Layered covalent organic framework having new structure

Abstract

Provided is a COF characterized by the following items (1) to (5). (1) Building block molecules used to generate the COF include a tetra-building block molecule having a functional group at the position of each vertex of a tetrahedron and a tri-building block molecule having a functional group at the position of each vertex of a triangle. (2) The functional group of the tetra-building block molecule and the functional group of the tri-building block molecule can form a covalent bond by condensation reaction therebetween. (3) The COF has a planar network constructed trough covalent bonds formed by periodic condensation of the tetra-building block molecule and the tri-building block molecule. (4) Layers of the planar network can be stacked on top of each other to form a layered material. (5) Three functional groups of four condensable functional groups of the tetra-building block molecule undergo condensation reaction with three functional groups of the tri-building block molecule to form covalent bonds, and the remaining one functional group remains facing the out-of-plane direction of the planar network.　The COF can be partially dissolved or dispersed in a liquid, and a COF film can be produced from the solution or the dispersion.

Description

Novel layered covalent organic frameworks

[0001] The present invention relates to a covalent organic framework (hereinafter referred to as COF) having unprecedented structural features and reactive functional group arrangement features, its derivatives, and uses thereof.

[0002] COFs are typically formed by periodically covalently bonding two (or in special cases, three or more) types of organic molecules (building block molecules) with two or more reactive functional groups. They generally possess high specific surface area, high thermal and chemical stability, and a composition consisting only of light elements (e.g., C, N, and O). Because of their flexibility in designing the functionality and pore size through the selection of building block molecules, they are a category of crystalline organic solids for which numerous applications have been proposed in recent years (e.g., Non-Patent Documents 1-7). However, in contrast to metal-organic frameworks (MOFs), which have been the leading research and development target, the relatively rigid covalent bonds that form COFs offer the advantages of high thermal and chemical stability, but also the disadvantage of difficulty in producing highly crystalline materials (e.g., Figure 1 in Non-Patent Document 3).

[0003] COFs have been broadly classified into two-dimensional and three-dimensional COFs. As explained in various review articles (e.g., Non-Patent Documents 1, 2, 5, 6, and 7), two-dimensional COFs are typically constructed by repeated condensation reactions of two types of "planar building block molecules with two to four reactive functional groups present in the same plane," resulting in a planar network of covalent bonds, which are then stacked together via hydrogen bonds and van der Waals forces. On the other hand, three-dimensional COFs are typically constructed by repeated condensation reactions of "stereoscopic building block molecules with four or more reactive functional groups not present in the same plane, e.g., reactive functional groups at each vertex of a tetrahedron," and "planar building block molecules with two to three reactive functional groups present in the same plane," resulting in a three-dimensional network of covalent bonds.

[0004] As cited in Non-Patent Documents 1 to 7, numerous papers on 2D COFs have been published to date, but with very few exceptions (e.g., Non-Patent Documents 8, 9, and 10), the crystallinity was extremely low in almost all of them. For example, Non-Patent Documents 11 to 17 show scanning electron microscope images of various 2D COFs (Figure S5 in Non-Patent Document 11; Figures 2, 6, S29, and S30 in Non-Patent Document 12; Figure S18 in Non-Patent Document 13; Figures 2, S14, and S15 in Non-Patent Document 14; Figure S7 in Non-Patent Document 15; Figures 3 and S30 in Non-Patent Document 16; and Figure 2 in Non-Patent Document 17). However, the shapes of these images are amorphous even at the magnification of the scanning electron microscope images, indicating that the crystallinity of all of these materials is extremely low.

[0005] In contrast, recent advances in COF growth techniques (e.g., Non-Patent Documents 18, 19, 20) have led to the development of numerous highly crystalline COFs, whose crystal shapes are clearly visible under an optical microscope. This indicates that 3D COFs have a distinct advantage over 2D COFs in that they are easier to enhance crystallinity. The authors of Non-Patent Document 21 provide an insight into the underlying reason for this, stating on page 8487: "Three-dimensional COFs are characterized by covalent connectivity in three independent directions, which leads to improved crystallinity as compared to two-dimensional COFs."

[0006] On the other hand, two-dimensional COFs are expected to have great potential for applications because their layered structure allows them to be deployed in devices and films on substrates (e.g., Non-Patent Documents 5 and 7). Therefore, if a "layered COF" like two-dimensional COF could be synthesized with the same high crystallinity as three-dimensional COFs, it would be expected that the feasibility of COF applications would be significantly increased, but this has not been achieved to date.

[0007] Furthermore, to broaden the range of applications of COFs, it is desirable to be able to add functional groups to the organic framework of COFs through post-reactions, thereby imparting targeted functionality. For example, several previous studies have demonstrated that reactive functional groups are incorporated into COFs produced in the first stage, and then functional groups with targeted functions are added through subsequent post-treatment (e.g., Non-Patent Documents 15, 22, 25).

[0008] Such introduction of a "reactive functional group" that can be used in a subsequent reaction step can also be achieved by leaving some of the reactive functional groups that can be used in COF formation unreacted. For example, in Non-Patent Document 15, aminoterephthalohydrazide (a building block molecule having two hydrazide groups and one amino group) was reacted with 4,4',4"-(1,3,5-triazine-2,4,6-triyl)-tribenzaldehyde (a building block molecule having two aldehyde groups) in a liquid, causing a condensation reaction between only the hydrazide groups of the former and the aldehyde groups of the latter to form a COF, while leaving the amino groups of the former unreacted. This unreacted amino group was successfully used in a functional group addition reaction in the subsequent step.

[0009] As another example of leaving unreacted functional groups after COF formation, for example, Non-Patent Documents 24 to 28 report that building block molecules having multiple aldehyde groups as reactive functional groups for COF formation react with building block molecules having multiple amino groups in a liquid, thereby successfully leaving unreacted aldehyde groups after COF formation. Furthermore, as yet another example, Non-Patent Document 13 reports that building block molecules having multiple aldehyde groups as reactive functional groups for COF formation react with building block molecules having multiple amino groups in a liquid, thereby successfully leaving unreacted amino groups after COF formation.

[0010] However, all of the prior art COFs that successfully retained unreacted functional groups after COF formation (Non-Patent Documents 13, 15, 24-28) were two-dimensional (2D) COFs with planar framework geometric structures. The nanopores of such two-dimensional COFs extend one-dimensionally in the normal direction to the layer plane (see, for example, Figure 11 in Non-Patent Document 1). Therefore, the unreacted functional groups successfully retained in these prior art studies were all in the in-plane direction of the two-dimensional COF, i.e., facing the interior of the one-dimensional nanopores. Therefore, even if further functionalization was attempted after COF formation, the size of the functional groups that could be added was fundamentally limited to those that fit within the pore width of the two-dimensional COF.

[0011] Xiao Feng et al., Chem. Soc. Rev. 2012, 41, 6010-6022 (DOI: 10.1039 / c2cs35157a)San-Yuan Ding et al., Chem. Soc. Rev. 2013, 42, 548 (DOI: 10.1039 / c2cs35072f)Juncong Jiang et al., J. Am. Chem. Soc. 2016, 138, 3255-3265 (DOI: 10.1021 / jacs.5b10666)Christian S. Diercks and Omar M. Yaghi, Science 2017, 355, aal1585 (DOI: 10.1126 / science.aal1585) Thomas Adsev. Funct. Matter. 2018, 28, 1705553 (DOI: 10.1002 / adfm.201705553)Keyu Geng et al., Chem. Rev. 2020, 120, 8814-8933 (DOI: 10.1021 / acs.chemrev.9b00550)Xinyi Chen et al., Angew. Chem. Hint. Ed. 2020, 59, 5050-5091 (DOI: 10.1002 / anie.201904291)Austin M. Evans et al., Science 2018, 361, 52-57 (DOI: 10.1126 / science.aar7883), Wang J. Am. Chem. Soc. 2023, 145, 12155-12163 (DOI: 10.1021 / jacs.3c01783)Anusree Natraj et al., J. Am. Chem. Soc. 2024, 146, 16775-16786 (DOI: 10.1021 / jacs.4c04674)Qing Xu et al., J. Am. Chem. Soc. 2018, 140, 7429-7432 (DOI: 10.1021 / jacs.8b03814)Gen Zhang et al., J. Am. Chem. Soc.2019, 141, 1227-1234 (DOI: 10.1021 / jacs.8b07670)Tanmay Banerjee et al., Nat. Common. 2019, 10, 2689 (DOI: 10.1038 / s41467-019-10574-6)Adrien P. Cote et al., Science 2005, 310, 1166-70 (DOI: 10.1126 / science.11X20) Tang et al., Appl. Matter. Interfaces 2023, 15, 24836-24845 (DOI: 10.1021 / acsami.3c02025)Congcong Yin et al., J. Am. Chem. Soc. 2023, 145, 11431-11439 (DOI: 10.1021 / jacs.3c03198)Shun Wan et al., Angew. Chem. Hint. Ed. 2009, 48, 5439-42 (DOI: 10.1002 / anie.200900881)Tianqiong Ma et al., Science 2018, 361, 48-52 (DOI: 10.1126 / science.aat7679)Xiaohan Wang et al., Chem. Common. 2021, 57, 6656-6659 (DOI: 10.1039 / d1cc01857d)Jing Han et al., Science 2024, 383, 1014-1019 (DOI: 10.1126 / science.adk8680)Frederik and Bettina V. Chem. Soc. Rev. 2020, 49, 8469-8500 (DOI: 10.1039 / d0cs01027h)Jesus A. Martin-Illan et al., Chem. Eur. J. 2020, 26, 6495-6498 (DOI: 10.1002 / chem.202000224)Hao Liu et al., J. Am. Chem. Soc. 2022, 144, 12989-12995 (DOI: 10.1021 / jacs.2c05382)Qiang Gao et al., Chem. Mater. 2018, 30, 1762-1768 (DOI: 10.1021 / acs.chemmater.8b00117)Bing Zhang et al., J. Am. Chem. Soc. 2019, 141, 11420-11424 (DOI: 10.1021 / jacs.9b05626)Qiaobo Liao et al., Sci. China Chem. 2020, 63, 707-714 (DOI: 10.1007 / s11426-019-9696-3)Canran Wang et al., Molecules 2023, 28, 449 (DOI: 10.3390 / molecules28010449)Mengjie Hao et al., J. Am. Chem. Soc. 2024, 146, 1904-1913 (DOI: 10.1021 / jacs.3c08160).

[0012] As mentioned above, the prior art had two unresolved problems. The first problem was that, in principle, it was difficult to achieve the high crystallinity achieved in three-dimensional COFs, in which covalent bonds can be formed in three independent directions, by combining planar building block molecules with 2 to 4 reactive functional groups in the same plane (as described in paragraph

[0003] ) to produce "layered COFs" suitable for a wide range of applications such as devices and membranes using the typical method for producing two-dimensional COFs, i.e., the method of extending two-dimensional covalent bonds by combining "planar building block molecules with 2 to 4 reactive functional groups in the same plane" (as described in paragraph

[0005] ).

[0013] The second problem is that even if unreacted functional groups can be left after the formation of 2D-COFs in conventional techniques (e.g., Non-Patent Documents 13, 15, 24-28), such unreacted functional groups are arranged toward the interior of the nanopores extending in the normal direction of the 2D-COF layer. Therefore, as long as such conventional 2D-COFs are used, the size of functional groups that can be added to such unreacted functional groups by post-treatment is limited to those that fit within the width of the nanopores, which is a spatial limitation.

[0014] The present invention aims to provide a new structural category of COFs that cannot be classified as either two-dimensional or three-dimensional COFs according to conventional classifications based on structural concepts, and that can be called "2.5-dimensional COFs" that are intermediate between the two. This discovery aims to provide a new group of COF materials, their derivatives, and their uses that can solve the problems that were fundamentally difficult to avoid with the above-mentioned conventional technologies.

[0015] As a result of extensive research to solve the above problems, the present inventors have found that the following novel COF groups and their derivatives can be generated by combining building block molecules having functional groups at each vertex of a tetrahedron with building block molecules having functional groups at each vertex of a triangle, and have completed the present invention based on these findings. That is, the present invention provides the following [1] to

[10] .

[0016] [1] A covalent organic framework (COF) characterized by the following (1) to (5): (1) The building block molecules used to generate the covalent organic framework are Tetra building block molecules having functional groups at each vertex of a tetrahedron and Tri building block molecules having functional groups at each vertex of a triangle; (2) The functional groups of the Tetra building block molecules and the Tri building block molecules can form covalent bonds between them through a condensation reaction (also called an addition-elimination reaction, hereinafter the same); (3) The covalent organic framework has a planar network constructed by covalent bonds formed by periodic condensation of the Tetra building block molecules and the Tri building block molecules; (4) The planar networks can be stacked to form layered materials; (5) Three of the four condensed functional groups of the Tetra building block molecules condense with three functional groups of the Tri building block molecules to form covalent bonds, and the remaining functional group remains facing out of the plane of the planar network.

[0017] [2] The covalent organic framework according to [1], wherein the covalent bond formed by periodic condensation of the Tetra building block molecules and the Tri building block molecules is a covalent bond between a C atom and a N atom.

[0018] [3] The covalent organic framework according to [1], wherein the remaining functional group is an amino group, an aldehyde group, or a trimethylammonium group.

[0019] [4] The covalent organic framework according to [1], wherein the covalent bond formed by the periodic condensation of the Tetra building block molecule and the Tri building block molecule is a covalent bond between a C atom and a N atom, and the remaining functional group is a trimethylammonium group.

[0020] [5] A solution or dispersion of a covalent organic framework, characterized in that the covalent organic framework according to [4] is dissolved or dispersed in a liquid.

[0021] [6] A method for preparing a film of a covalent organic framework, comprising the steps of pouring a solution or dispersion of the covalent organic framework according to [5] onto a substrate having holes, and depositing the covalent organic framework on the substrate.

[0022] [7] A gas adsorbent containing the covalent organic framework according to [1].

[0023] [8] A separation membrane comprising the covalent organic framework according to [1].

[0024] [9] A drug delivery carrier comprising the covalent organic framework according to [1].

[0025]

[10] A derivative of the covalent organic framework according to [1], formed by modifying an unreacted functional group of the covalent organic framework with another compound through a reaction.

[0026] This specification includes part or all of the contents as disclosed in the specification and / or drawings of Japanese Patent Application No. 2024-116037, which is a priority document of the present application.

[0027] The present invention provides a novel COF that can be called a "2.5-dimensional COF," which cannot be classified as either a two-dimensional COF or a three-dimensional COF according to the typical conventional definitions. This enables the production of layered COFs with high crystallinity and large size, and significantly expands the potential applications of COFs.

[0028] Schematic diagram of Tetra building block molecules and Tri building block molecules. Schematic diagram of a planar network constructed by covalent bonds formed by the periodic condensation of Tetra building block molecules and Tri building block molecules. Schematic diagram of the layered structure of the planar network and the COF crystal of the present invention. Building block molecules of new COF-1 and new COF-2. Synthetic procedures for new COF-1 and new COF-2. Details are shown in Table 1. Powder X-ray diffraction (PXRD) data for new COF-1 (synthesis conditions I and II, measured in acetonitrile). Powder X-ray diffraction (PXRD) data for new COF-2 (synthesis conditions III and IV, measured in acetonitrile). Optical (polarized) microscope image of new COF-1 (synthesis condition I). Optical (polarized) microscope image of new COF-2 (synthesis condition III). Comparison of Fourier transform infrared (FT-IR) spectra. From bottom to top: spectra of new COF-2, new COF-1, TFPB, TFPT, and TAM. Comparison of powder X-ray diffraction (PXRD) patterns. From the bottom, diffraction patterns of new COF-2, new COF-1, TFPB, TFPT, and TAM. Comparison of PXRD patterns of new COF-1 under synthesis conditions III and IV. 15 N solid-state nuclear magnetic resonance ( 15 N ss-NMR measurement results. 13 C solid-state NMR spectrum of new COF-2 13C solid-state NMR spectrum. X-ray photoelectron spectroscopy (XPS) spectrum of new COF-1. XPS spectrum of new COF-2. Structure of new COF-1 determined by single crystal X-ray diffraction (SCXRD). This figure shows the asymmetric unit of the structure refined by analysis. Thermal ellipsoids have a 50% probability of existence. Structure of new COF-2 determined by SCXRD. This figure shows the asymmetric unit of the structure refined by analysis. Thermal ellipsoids have a 50% probability of existence. Comparison of the PXRD pattern obtained from a crystal of new COF-1 in acetonitrile with a simulated pattern generated from the crystal structure determined by SCXRD analysis. Comparison of the PXRD pattern obtained from a crystal of new COF-2 in acetonitrile with a simulated pattern generated from the crystal structure determined by SCXRD analysis. Plane index of the new COF-1 crystal determined from SCXRD measurement. The figure on the left is a photograph of a crystal of new COF-1 taken with the camera attached to the SCXRD instrument. The right figure is a schematic diagram of the new COF-1 crystal with the plane indices determined from the left figure. The plane indices of the new COF-2 crystal determined from SCXRD measurements. The left figure is a photograph of the new COF-2 crystal taken with the camera attached to the SCXRD instrument. The right figure is a schematic diagram of the new COF-2 crystal with the plane indices determined from the left figure. The crystal structure of new COF-1 determined from SCXRD measurements and data analysis. The schematic crystal diagram shows the correspondence between the viewing direction of the crystal structure and the viewing direction of the crystal outer shape. The dashed line (2.7 Å) in the bottom right figure indicates a hydrogen bond. The crystal structure of new COF-2 determined from SCXRD measurements and data analysis. The schematic crystal diagram shows the correspondence between the viewing direction of the crystal structure and the viewing direction of the crystal outer shape. The dashed line (2.4 Å) in the bottom right figure indicates a hydrogen bond. High-resolution transmission electron microscope (HR-TEM) image of new COF-1. HR-TEM image of new COF-2. PXRD patterns of new COF-1 and new COF-2 in the dry state. Scanning electron microscope (SEM) image of new COF-1. SEM image of new COF-2. Atomic force microscope (AFM) image of new COF-1. AFM image of new COF-2. Thermogravimetric analysis (TGA) results for new COF-1. Solid line indicates in air, dashed line indicates in nitrogen. TGA results for new COF-2. Solid line indicates in air, dashed line indicates in nitrogen.Measurement results of nitrogen adsorption isotherms (77 K) for new COF-1 and new COF-2. Pore size distribution for new COF-1. Pore size distribution for new COF-2. CO2 adsorption / desorption measurement results for new COF-1 (temperature: 273 K, 285.5 K, 298 K). CO2 adsorption / desorption measurement results for new COF-2 (temperature: 273 K, 285.5 K, 298 K). Heat of adsorption (Q) for new COF-1 and new COF-2. st ) Calculation results. N2 adsorption / desorption measurement results for new COF-1 (temperature: 273 K, 298 K). N2 adsorption / desorption measurement results for new COF-2 (temperature: 273 K, 298 K). Calculation results of IAST selectivity for new COF-1 and new COF-2 for a CO2:N2 = 15:85 (v:v) mixed gas (temperature: 273 K). Calculation results of IAST selectivity for new COF-1 and new COF-2 for a CO2:N2 = 15:85 (v:v) mixed gas (temperature: 298 K). The inventive step of new COF-1 and new COF-2 of the present invention, compared with COFs from previous studies. The lower the heat of adsorption, the better, and the higher the IAST selectivity. In other words, the more favorable the position in the upper right corner of this figure, the better. Optical microscope image of a derivative of new COF-1 produced by post-treatment modification of the residual amino groups of new COF-1. FT-IR spectrum of the derivative of new COF-1 produced by post-treatment of the residual amino groups of new COF-1. This is compared with the FT-IR spectrum before modification. New COF-2-N + A photograph showing the state of DMF to which COF-2-NH-N was added. A diagram comparing the amount of solid precipitate before and after heat treatment and over time after treatment. + Photograph showing the state of DMF after addition of new COF-1-NH-N + Photographs showing the state of PTFE filter paper (left) and new COF-1 (right) dispersed in water. + Scanning electron microscope (SEM) image of the PTFE filter paper (right) after filtration. New COF-1-NH-N + Photograph of laser light irradiated on the DMF solution of PTFE filter paper (left) and new COF-1-NH-N + Scanning electron microscope (SEM) image of the PTFE filter paper (center) after filtration. The SEM image on the right is an enlarged portion of the SEM image in the center.

[0029] The present invention is described in detail below. In this specification, a "covalent organic framework (COF)" is defined as a crystalline organic solid formed by covalent bonds. Furthermore, a "building block molecule" is defined as a molecule that can be used as a raw material for forming a COF.

[0030] The COF of the present invention is characterized by the following (1) to (5): (1) The building block molecules used to produce the COF are Tetra building block molecules having functional groups at each vertex of a tetrahedron and Tri building block molecules having functional groups at each vertex of a triangle.

[0031] The Tetra building block molecules are not necessarily regular tetrahedrons, and the Tri building block molecules are not necessarily equilateral triangles.

[0032] The functional group can be, but is not limited to, an amino group or an aldehyde group, as shown in the examples. The functional groups of COF building block molecules are well documented, and appropriate functional groups can be selected according to the descriptions in these documents. For example, Diercks et al., Science 2017, eaal1585, (DOI: 10.1126 / science.aal1585) describes bonds formed by condensation of functional groups, including (i) BO bonds (boroxine, boronic ester, borosilicate, spiroborate), (ii) C=N bonds (imine, hydrazone, squaraine), and (iii) C=N bonds. (aromatic) Examples include (i) a C═C bond (triazine, phenazine), (ii) a C═C bond (alkene), (iii) a C═C bond (β-ketoenamine, imide, amide), and (iv) a B═N bond (borazine). In the present invention, functional groups that form these bonds can also be selected.

[0033] Examples of suitable building block molecules include tetrakis(4-aminophenyl)methane (TAM) and tetrakis(4-formylphenyl)silane (TFS). Examples of suitable building block molecules include, but are not limited to, 2,4,6-tris(4-formylphenyl)-1,3,5-triazine (TFPT), 1,3,5-tris(4-formylphenyl)benzene (TFPB), and 1,3,5-tris(4-aminophenyl)benzene (TPB). Many literature documents have been published regarding COF building block molecules, and appropriate building block molecules can be selected according to the literature.

[0034] (2) The functional group of the Tetra building block molecule and the functional group of the Tri building block molecule are capable of forming a covalent bond by a condensation reaction therebetween.

[0035] (3) The COF has a planar network constructed by covalent bonds formed by periodic condensation of the Tetra building block molecules and the Tri building block molecules.

[0036] As shown in the schematic diagram in Figure 2, the geometric dimensionality of the chemical bonds that make up this network is three-dimensional (stereoscopic), but the network viewed macroscopically is planar and two-dimensional.

[0037] The "covalent bond formed by periodic condensation of the Tetra building block molecule and the Tri building block molecule" may be a covalent bond between a C atom and an N atom. The covalent bond between a C atom and an N atom is a covalent bond formed by a condensation reaction between functional groups of the building blocks, but this covalent bond may be converted into another covalent bond by various treatments. For example, a C=N bond (imine bond) formed by the condensation reaction of an amino group and an aldehyde group may be converted into a covalent bond between a C atom and an N atom, such as a C-NH bond (a bond containing a secondary amine).

[0038] (4) The planar networks can overlap with each other to form layered materials.

[0039] As shown in the schematic diagram of Figure 3, the planar networks can become layered materials by being bound to each other in the direction normal to the plane by "bonds or attractive forces weaker than covalent bonds," such as hydrogen bonds or van der Waals forces.

[0040] (5) Three of the four functional groups of the Tetra building block molecule react with three functional groups of the Tri building block molecule to form covalent bonds, and the remaining functional group remains facing out of the plane of the planar network.

[0041] As shown in Figure 2, only three of the four functional groups of the Tetra building block molecule are used to form covalent bonds with the Tri building block molecule, leaving one functional group of the Tetra building block molecule unreacted. As a result, the COF of the present invention has an innovative feature not seen in conventional COFs: a high density of functional groups (e.g., amino groups and aldehyde groups) oriented out of the plane of the layer.

[0042] The "one remaining functional group" mentioned above is a functional group originally possessed by the building block, but this functional group may be converted into another functional group by various treatments. For example, an amino group may be treated with an alkylating agent (e.g., iodomethane) to convert it into a quaternary ammonium cation, resulting in a trialkylammonium group (e.g., trimethylammonium group). Converting the amino group into a trialkylammonium group can increase the solubility in liquids such as water.

[0043] As described above, the COFs of the present invention have a high density of reactive functional groups (e.g., amino groups and aldehyde groups) oriented out of the plane of the planar covalent bond network. Because these reactive functional groups can be used to bind drugs, the COFs of the present invention can also be used as carriers for drug delivery. The advancement of the present invention over previous inventions is that in previous COFs with unreacted functional groups, the functional groups were oriented in the in-plane direction of the two-dimensional COF layer, limiting the usefulness of functional groups to those that fit within the pores that expand normal to the two-dimensional COF layer. In contrast, the unreacted functional groups of the present invention are oriented normal to the layer, making it possible, in principle, to add functional groups without size restrictions to the free space after the layer is broken down.

[0044] The COF of the present invention can also be used as a gas adsorbent. For example, it can be used as a carbon dioxide adsorbent, as described below. COFs are also used as adsorbents for gases other than carbon dioxide, energy storage (F. Xu et al., Chem. Sci., 10, 6001 (2019)), catalysts (H. Hu et al., Chinese J. Catal., 39, 1167 (2018)), semiconductors (M. Zhang et al., Angew. Chem. Int. Ed., 59, 6500 (2020)), and ion and molecule separation membranes (Q. Xu et al., ACS Appl. Energy Mater., 2, 5793 (2019)). Therefore, the COF of the present invention can also be used for any of these applications. The gases referred to here include water vapor and harmful gases.

[0045] A derivative of the COF of the present invention can also be produced by modifying the unreacted functional groups of the COF of the present invention with another compound through some kind of chemical reaction.

[0046] By replacing the "remaining functional group" in the COF of the present invention with a trialkylammonium group, the COF of the present invention can be solubilized or dispersed in a liquid (e.g., water, N,N-dimethylformamide, etc.). Furthermore, a similar effect can be achieved by replacing the "covalent bond formed by the periodic condensation of the Tetra building block molecule and the Tri building block molecule" in the COF of the present invention with a trialkylammonium group. Solutions or dispersions containing such COFs can be used for a variety of purposes. For example, a COF film can be produced by pouring the solution or dispersion onto a porous substrate and depositing the COF on the substrate. Examples of porous substrates include filter paper, filters, and porous membranes (e.g., anodized alumina).

[0047] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0048] Example 1 1. Preparation of COFs 1.1 Reagents Used Tetrakis(4-aminophenyl)methane (TAM, purity ≥ 95%) was purchased and used as the Tetra building block molecule, and 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde (TFPT, purity ≥ 97%) and 1,3,5-tris(4-formylphenyl)benzene (TFPB, purity 98%) were purchased and used as the Tri building block molecules. 1,4-Dioxane (purity 99.5+%) and o-dichlorobenzene (o-DCB, purity > 99.0%) were purchased and used as COF synthesis solvents, acetic acid (AcOH, purity 99.5+%) was purchased and used as the catalyst, and aniline (purity ≥ 99.5%) and m-toluidine (purity 99.0+%) were purchased and used as equilibration adjusters.

[0049] 1.2 Created COFs In this example, two types of COFs were created: new COF-1, which was created by combining TAM and TFPT, and new COF-2, which was created by combining TAM and TFPB (Figure 4).

[0050] 1.3 COF Synthesis Procedure. COF synthesis was performed in seven steps (steps 1 to 7) as shown in Figure 5. The specific conditions for each step are summarized in Table 1. As shown in Table 1, two conditions were used for each type of COF (conditions I and II for new COF-1, and conditions III and IV for new COF-2) depending on the measurement objective. Based on experience, conditions I and III have low yields but large crystal sizes, making them suitable for optical microscopy and single-crystal X-ray diffraction. Conditions II and IV have small crystal sizes but high yields, making them suitable for characterization, which requires a large sample amount. Conditions I and II (new COF-1) and conditions III and IV (new COF-2) were confirmed to produce the same product based on the identical powder X-ray diffraction (PXRD) patterns (Figures 6 and 7).

[0051] Specifically, the COFs were synthesized according to the steps shown in Figure 5 and the conditions summarized in Table 1. One mole of TFPT or TFPB is defined as "1 equiv." First, TFPT or TFPB powder was placed in a screw-cap glass vial (volume: 5 mL or 10 mL). Next, o-DCB was added to the vial and ultrasonically dispersed using a bath-type sonicator (3510-DTH, Branson). Next, AcOH and a modulator (aniline or m-toluidine) were added to the vial and further ultrasonically dispersed. Subsequently, a 50 mM solution of TAM in 1,4-dioxane, prepared in a separate vial and filtered through a PTFE filter (pore size 200 nm, SLLGX13NL, Merck-LG), was added. Finally, the mixture was homogenized by ultrasonic dispersion for approximately 1 minute or by gently shaking the vial by hand. The capped vials were placed in a temperature-controlled incubator at 22°C until crystals large enough to be measured had formed (usually 2 to 11 days).

[0052] 1.4 Elemental Analysis (EA) Results Elemental analysis (EA) was performed using a Micro Corder JM10 (J-Science). Before EA, the sample was washed (described below) and then vacuum dried at 80 °C for 12 hours with a 50 sccm flow of dry nitrogen. The results, as summarized in Table 2 below, were in good agreement with the elemental composition calculated from the results of single crystal X-ray diffraction (SCXRD) measurements (described below). The synthesis conditions used were II (New COF-1) and IV (New COF-2).

[0053] 2. Sample Characterization and Analysis Methods 2.1 Sample (Crystal) Cleaning Treatment Prior to Characterization Most of the COF crystals formed adhered to the bottom and inner walls of the vial. First, the solvent was replaced twice with o-DCB to remove AcOH, equilibration agents, and intermediate products. After that, the o-DCB was replaced twice with N,N-dimethylacetamide (DMA; purity > 99.0%, TCI). The COF crystals adhering to the inner walls of the vial were easily removed by gently mechanically scraping the inner walls with the tip of a Pasteur pipette. The DMA containing the suspended crystals was then divided into several Eppendorf tubes (volume: 1.5 mL) and centrifuged.

[0054] For characterization of samples requiring large amounts of dry crystals, the supernatant DMA was replaced twice with toluene (purity 99.5%; Fujifilm Wako Chemicals) to remove the DMA. Toluene was used here because it has been reported that using a nonpolar solvent can minimize surface tension damage that may occur to the COF pores during the subsequent drying process. [1] Finally, the crystals were collected on filter paper and dried in vacuum at 80 °C for 12 hours while flowing dry nitrogen at 50 sccm.

[0055] 2.2 Optical Microscopy Optical microscopy images were acquired using a polarizing microscope (BX53, Olympus) equipped with a CMOS camera. Polarizing microscopy images were acquired using a rotatable sample stage and a pair of polarizers adjusted in a crossed Nicol configuration with a 530 nm retarder. The optical microscopy images shown in Figures 8 and 9 are of COF crystals grown under synthesis conditions I (New COF-1) and III (New COF-2), respectively.

[0056] 2.3 Fourier transform infrared (FT-IR) spectroscopy Fourier transform infrared (FT-IR) spectra were obtained using an FT / IR-6100 (JAFCO) with a single attenuated total reflection unit (ATR unit, prism material: germanium). During the measurements, the sample chamber was evacuated to eliminate the influence of outside air. Prior to the measurements, the COFs were dried in vacuum at 80 °C for 12 hours while flowing dry nitrogen at 50 sccm. The synthesis conditions for the samples used in the measurements were II (new COF-1) and IV (new COF-2).

[0057] 2.4 Solids 13 C and 15 N Nuclear Magnetic Resonance (ss-NMR) Spectroscopy Solid-state nuclear magnetic resonance (ss-NMR) measurements were performed using a FT-NMR spectrometer (JNM-ECA400, JEOL) with magic angle spinning (MAS). The spectra were obtained using a 9.39 T standard bore magnet. The Larmor frequency was 1 H, 13 C. 15 For measurements of N nuclei, the frequencies were 399.78 MHz, 100.53 MHz, and 40.51 MHz, respectively. 13 C and 15 Cross-polarization (CP) MAS experiments on N were performed using a standard 3.2 mm double-resonance HX probe. 13 C is 18 kHz, 15 N was performed at a sample spinning rate of 14.5 kHz. CP / MAS experiments were performed using the RAMP-CP [2] and 1 H TPPM [3] Using decoupling, 1The H RF amplitude was approximately 100 kHz for decoupling and approximately 88 kHz for CP, with a contact time of 3 ms and a pulse delay of 1 s. 1 H TPPM decoupling is about 100 kHz, RAMP-CP is about 40 kHz ( 1 H) and approximately 11 kHz to 20 kHz ( 15 N), acquired with a contact time of 3 ms and a pulse delay of 1 s. 13 C and 15 The N chemical shifts were referenced relative to tetramethylsilane and CH3NO2, respectively, with 0 ppm. Prior to the measurements, the samples were dried in vacuum at 80 °C for 12 hours under a 50 sccm flow of dry nitrogen. The synthesis conditions for the samples used in the measurements were II (new COF-1) and IV (new COF-2).

[0058] 2.5 X-ray photoelectron spectroscopy (XPS) X-ray photoelectron spectroscopy (XPS) of the sample was performed using a photoelectron spectrometer (VersaProbe III, ULVAC-PHI) by irradiating Al Kα radiation. Since COF is an electrical insulator, charge correction was performed during measurement. The obtained spectrum was analyzed using a PHI MultiPak （登録商標） Curve fitting was performed using software. Before measurement, the COFs were vacuum dried at 80 °C for 12 hours under a 50 sccm flow of dry nitrogen. The synthesis conditions for the samples used in the measurement were II (New COF-1) and IV (New COF-2).

[0059] 2.6 Powder X-ray diffraction (PXRD) measurements PXRD measurements were carried out using an automatic X-ray diffractometer (SmartLab, Rigaku) ​​with Cu Kα radiation (λ = 1.54184 Å) at 40 kV and 50 mA.

[0060] The PXRD patterns of the building block molecules (TAM, TFPT, and TFPB) were measured using powders packed into a borosilicate glass capillary (diameter: 0.7 mm) at a scan rate and rotation speed of 1.0° min . -1The PXRD patterns of COFs in acetonitrile sealed in borosilicate glass capillaries (0.5 mm diameter) were acquired at a scan rate and rotation speed of 0.2° min , respectively. -1 and 120 rpm. PXRD patterns of the dry COFs were acquired in reflection mode with Bragg-Brentano geometry at a scan rate of 0.2° min -1 The synthesis conditions for the samples used in the measurements were I and II (New COF-1), and III and IV (New COF-2).

[0061] 2.7 Scanning Electron Microscopy (SEM) Sample observations using a scanning electron microscope (SEM) were performed using an SU8000 Type II (Hitachi High-Tech) at an accelerating voltage of 1.0 kV and a working distance of 8 mm. The mechanical treatment of new COF-1 crystals (Figures 28 and 30) and new COF-2 crystals (Figure 31) was carried out as follows. First, the crystals were washed with o-DCB and DMA according to the procedure described in 2.1. Next, the crystals were transferred to propylene carbonate in a screw-capped glass vial (volume: 6 mL) and mechanically stirred with a PTFE-coated magnetic stirrer at room temperature for 2 days. Subsequently, they were ultrasonically dispersed for 30 minutes using an ultrasonic bath (3510-DTH, Branson). Immediately after this, the treated crystals dispersed in propylene carbonate were cast onto a piece of silicon wafer (approximately 1 cm × 1 cm) and vacuum dried at 80 °C for approximately 18 to 24 hours under a flow of 50 sccm of dry nitrogen.

[0062] The new COF-2 crystals observed in Figure 29 were prepared by casting the crystals dispersed in propylene carbonate onto a silicon wafer piece (approximately 1 cm x 1 cm) and vacuum drying for approximately 18 to 24 hours at 80°C while flowing 50 sccm of dry nitrogen. The samples in Figures 28 and 30 were synthesized under condition II (new COF-1), the sample in Figure 29 was synthesized under condition III (new COF-2), and the sample in Figure 30 was synthesized under condition IV.

[0063] 2.8 Atomic Force Microscopy (AFM) For the atomic force microscopes (AFM) shown in Figure 30 (New COF-1) and Figure 31 (New COF-2), a Cypher S (Oxford Instruments) was used, using a sample crystal mechanically treated according to the method described in 2.7. The AFM probe used was an AC200-TS (Olympus). Image processing and analysis were carried out by Gwyddion. （登録商標） This was done using software.

[0064] 2.9 Single-crystal X-ray diffraction (SCXRD) measurement and crystal structure analysis Before the measurement, the crystal was soaked in o-DCB and an ionic liquid (methyltrioctylammonium bis(trifluoromethylsulfonyl)imide, [N 8881 The crystals were stored in a 2:1 (v:v) mixture of o-DCB and ionic liquid (NTf2, 99% purity, Iolitec) to prevent volatilization of o-DCB. A suitable crystal was then picked up, covered with a drop of the o-DCB and ionic liquid mixture, and mounted on a sample pin using inert oil (LV CryoOil, MiTeGen) for SCXRD measurements. SCXRD measurements of new COF-1 and new COF-2 were performed using a CrysAlisPro （登録商標） The analysis was performed using a software-controlled single-crystal X-ray diffractometer (XtaLAB Synergy-DW, Rigaku) ​​with Cu Kα radiation (λ = 1.54184 Å) at a temperature of 93.15 K. The crystal structures of new COF-1 and -2 were solved by SHELXT, and the structures were analyzed by SHELXL and Olex2. （登録商標） The software performed least-squares refinement using DFIX, SADI, ISOR, and FLAT restraints. Non-hydrogen atoms were refined with anisotropic thermal factors, and hydrogen atoms were placed in calculated positions treated in isotropic ride atom mode. Disorder of the o-DCB solvent molecules was controlled by Olex2 （登録商標） The crystal plane indexes of New COF-1 and New COF-2 were calculated using the CrysAlisPro software, which was based on the images of the sample crystals (taken with a camera built into the instrument) and the crystal orientation. （登録商標） The synthesis conditions for the samples used in the measurements were I (New COF-1) and III (New COF-2).

[0065] 2.10 High-resolution transmission electron microscope (HR-TEM) measurements were performed using a spherical aberration-corrected transmission electron microscope (R005, Jeol) operating at an accelerating voltage of 80 kV. To reduce the sample thickness and ensure electron beam transmission, the sample crystal was mechanically treated according to the method described in 2.7. After this treatment, the solvent was replaced with toluene. The sample suspended in toluene was dropped onto an ultrathin carbon-coated TEM grid (3150C, ALLIANCE Biosystems, carbon thickness: 5 nm, grid material: copper, mesh density: 300). Before observation, the TEM grid was vacuum-dried at 80 °C for 12 h under a 50 sccm flow of dry nitrogen. The samples used for observation were synthesized under the conditions of II (new COF-1) and IV (new COF-2).

[0066] 2.11 Thermogravimetric analysis (TGA) A thermogravimetric differential thermal analyzer (Thermo Plus EVO2, Rigaku) ​​was used, and the flow rate of air or nitrogen was set to 150 mL min -1 , heating rate 5 °C min -1 Before the measurement, the samples were dried under vacuum at 80 °C for 12 hours with a flow of dry nitrogen at 50 sccm. Typically, 3 to 5 mg of sample was loaded onto a platinum pan. The synthesis conditions for the samples used for the measurement were II (New COF-1) and IV (New COF-2).

[0067] 2.12 Gas Adsorption Isotherm Measurement The adsorption and desorption isotherms of the samples were obtained using 3Flex (Micromeritics). The samples dried according to the method described in 2.1 were further degassed before measurement according to the following procedure. First, a glass tube containing the sample (usually 80 mg to 100 mg) was evacuated at 90 °C for 6 hours using a homemade vacuum device. The glass tube was then attached to the 3Flex, and further degassed at 100 °C for 12 hours under ultrahigh vacuum using the equipped mantle heater.

[0068] Nitrogen adsorption / desorption isotherms were obtained using high-purity nitrogen gas (purity ≥ 99.9995%) at 77 K, 273 K, and 298 K. CO2 adsorption / desorption isotherms were obtained using high-purity CO2 gas (purity: 99.999%) at 273 K, 285.5 K, and 298 K. Between successive measurements under different conditions, the sample was degassed again at 100 °C for 2 to 4 hours using the built-in mantle heater.

[0069] Data analysis was performed using 3Flex software (version 5.01). The specific surface area was estimated by fitting the N2 adsorption isotherm at 77 K (Figure 34) with the Brunauer-Emmett-Teller (BET) theory. The pore size distribution was calculated by applying the nonlocal density functional theory to the same N2 adsorption isotherm. The synthesis conditions of the samples used for the measurements were II (New COF-1) and IV (New COF-2).

[0070] 2.13 Calculation of CO2 / N2 adsorption selectivity First, the CO2 and N2 adsorption isotherms at 273 K and 298 K obtained for New COF-1 and New COF-2 (Figures 37, 38, 40, and 41) were calculated using the following Freundlich-Langmuir equation: [4] The fitting was performed using the following equation.

[0071] The CO2 / N2 adsorption selectivity is calculated using the ideal adsorption solution theory (IAST) as follows: [5,6] was calculated using

[0072] 2.14 Heat of adsorption (Q st ) Evaluation of the heat of adsorption of the new COF at the CO2 adsorption amount n is Q st (n) and calculated based on the following Clausius-Clapeyron equation.

[0073] 3. Results and Discussion Optical microscope images obtained in this study are shown in Figure 8 (New COF-1, condition I) and Figure 9 (New COF-2, condition III). Single crystals up to approximately 100 μm in size were obtained with the new COF.

[0074] FT-IR measurements showed that New COF-1 and New COF-2 have the same peak of the aldehyde group of the aldehyde raw material molecule (TFPF: 1710 cm -1 , TFPB: 1687 cm -1 ) disappeared, and a new peak of imine bond (new COF-1: 1622 cm -1 , New COF-2: 1623 cm -1 ) appeared. This indicates that a product was obtained by the condensation reaction between the building block molecules. The measurement results are shown in Figure 10.

[0075] The PXRD patterns of the building block molecules and new COF-1 and new COF-2 are shown in Figure 11. The lowest diffraction angles of new COF-1 and new COF-2 were 2θ = 4.8-4.9°, which corresponds to a lattice spacing of approximately 1.9 nm, indicating the presence of a long-period structure in these COFs. The synthesis conditions for the samples used in the measurements were Condition II (new COF-1) and Condition IV (new COF-2).

[0076] 15 The results of N solid-state NMR measurements are shown in Figure 12. Chemical shifts indicating amino groups (new COF-1: -327.8 ppm, new COF-2: -327.0 ppm), triazine structures (new COF-1: -127.0 ppm), and imine bonds (new COF-1: -46.3 ppm, new COF-2: -51.4 ppm) were observed. These chemical shifts clearly demonstrate the formation of covalent bonds (imine bonds) in this COF, as well as the presence of unreacted amino groups (primary amines), which is a characteristic of this COF.

[0077] 13 The results of C solid-state NMR are shown in Figure 13 (New COF-1) and Figure 14 (New COF-2). In this measurement, chemical shifts indicating the central carbon of TAM (New COF-1: 63.6 ppm, New COF-2: 63.5 ppm) and chemical shifts indicating imine bonds (New COF-1: 158.4 ppm, New COF-2: 156.3-159.1 ppm) were observed, confirming the formation of this COF.

[0078] ​​The results of XPS measurements are shown in Figure 15 (New COF-1) and Figure 16 (New COF-2). These measurements revealed binding energies indicative of imine bonds (New COF-1: 398.2 eV, New COF-2: 398.02 eV), triazine structures (New COF-1: 399.59 eV), and amino groups (primary amines) (New COF-1: 400.84 eV, New COF-2: 400.13 eV). These results also support the formation of covalent bonds (imine bonds) in this COF, as well as the presence of unreacted amino groups (primary amines), a characteristic of this COF.

[0079] The above measurement results of FT-IR, PXRD, solid-state NMR, and XPS indicated the chemical bonding state, carbon skeleton, and crystallinity of the product of the present invention. However, the crystal structure obtained by the following SCXRD measurement, SEM observation image, and AFM image clearly demonstrate that the product of the present invention is a layered material.

[0080] Because new COF-1 and new COF-2 have relatively large crystal sizes, their crystal structures could be determined by SCXRD measurements. The results of the crystal structure analysis are shown in Figure 17 (new COF-1) and Figure 18 (new COF-2). Tables 3 and 4 show the crystal data and structure refinement parameters for new COF-1 and new COF-2, respectively. Figures 17 and 18 show the single crystal structures of the asymmetric units of new COF-1 and new COF-2, respectively, with thermal ellipsoids at a 50% probability of existence. For structure refinement, disordered solvent molecules were modeled and a solvent musk of o-DCB was applied.

[0081] Next, the simulated diffraction pattern generated from the crystal structure was consistent with the actually measured PXRD pattern (Figures 19 and 20), and it was found that the lowest peak at a diffraction angle 2θ = 4.8 to 4.9° corresponds to the (020) plane.

[0082] This measurement also identified the plane index of the crystal shape. The results are shown in Figure 21 (New COF-1) and Figure 22 (New COF-2). These results indicate that the front face, where the hexagon is visible, is the (101) plane. These results reveal that New COF-1 and New COF-2 of the present invention are COFs with a novel structure, in which one of the four amino groups on TAM remains unreacted, resulting in a three-dimensional (stereoscopic) microscopic chemical bond, but a two-dimensional (planar) covalent bond network macroscopically. This structure does not fit the structural description typically used for conventional "2D COFs" and "3D COFs." Because this structure is intermediate between 2D and 3D COFs, it belongs to a new structural category that could be called a "2.5D COF."

[0083] The structures revealed by single-crystal X-ray crystallography are shown in Figure 23 (New COF-1) and Figure 24 (New COF-2). This structure shows the presence of hydrogen bonds between the H of the primary amine and the N of the imine bond between adjacent layers, and the H...N and N-N distances (approximately 2.4-2.7 Å and approximately 3.2-3.3 Å, respectively) are comparable to the previously reported values ​​for N-H...N bonds. [7,8,9] .

[0084] HR-TEM images are shown in Figure 25 (new COF-1) and Figure 26 (new COF-2). The (101) plane of the new COF was observed from a direction that confirmed the hexagonal crystal shape. A lattice spacing with a period of approximately 1.9 nm was observed in the

[0010] direction, which coincided with the lattice spacing (approximately 1.9 nm) of the determined structures of new COF-1 and new COF-2. This also quantitatively coincided with the diffraction angle 2θ = 4.6–4.9°, which corresponds to a period of 1.8–1.9 nm in the PXRD patterns of new COF-1 and new COF-2 in the dry state (Figure 27).

[0085] SEM images are shown in Figure 28 (New COF-1) and Figure 29 (New COF-2). Figure 28 shows the observation after treatment (stirring and ultrasonic dispersion in propylene carbonate) to thinly exfoliate the crystal layer produced under condition II. Figure 29 shows the observation of the crystal produced under condition III. Both SEM images clearly show that the new COF has a layered structure.

[0086] The results of AFM observation are shown in Figure 30 (New COF-1) and Figure 31 (New COF-2). The observation samples used were crystals produced under synthesis condition II (New COF-1) and condition IV (New COF-2), which had been subjected to a layer peeling process. Both results show the presence of steps of several nanometers, clearly indicating that the new COF in question has a layered structure.

[0087] The results of thermogravimetric analysis in air and nitrogen are shown in Figure 32 (New COF-1) and Figure 33 (New COF-2). Both New COF-1 and New COF-2 showed extremely high thermal stability, exceeding 300°C in air and 400°C in nitrogen.

[0088] The results of the nitrogen adsorption isotherm are shown in Figure 34. The pore size distributions obtained by the NLDF method are shown in Figure 35 (New COF-1) and Figure 36 (New COF-2). The nitrogen adsorption isotherm results were Type I adsorption isotherms, which are characteristic of microporous materials, where adsorption occurs in the low relative pressure region. Next, the BET plot showed that the specific surface area was 533 m 2 g -1 (New COF-1), 348 m 2 g -1 The new COF was found to be (New COF-2), and the new COF exhibited a high specific surface area. Finally, the pore size distribution indicated that the new COF was a porous material with nanopores of approximately 1 nm.

[0089] The results of the CO2 adsorption / desorption measurements are shown in Figure 37 (New COF-1) and Figure 38 (New COF-2). Measurements were performed at three temperatures: 273 K, 285.5 K, and 298 K. At 273 K, the maximum CO2 adsorption amount was 55 cm. 3 g -1 (New COF-1), 45 cm 3 g -1(New COF-2). The heat of adsorption (Q st The average heat of adsorption of the new COF was 25.5 kJ mol -1 (New COF-1) and 25.3 kJ mol -1 (New COF-2).

[0090] The results of the nitrogen adsorption / desorption isotherms are shown in Figure 40 (New COF-1) and Figure 41 (New COF-2). The measurement temperatures were 273 K and 298 K. At 273 K, the New COF showed a maximum of 3 cm 3 g -1 The nitrogen adsorption amount was about 100%.

[0091] The calculation results of IAST selectivity of CO2 and N2 under a CO2:N2 = 15:85 (v:v) mixed gas are shown in Figure 42 (273 K) and Figure 43 (298 K). st The results of comparing the IAST selectivity values ​​of CO2 and N2 under a CO2:N2 = 15:85 (v:v) gas mixture with those of COF in previous studies are shown in Figure 44 and Table 5. In general, the selectivity and Q of gas adsorption st There is a trade-off between the Q and Q values. In other words, a material with high (low) gas adsorption selectivity has a high (low) Q st However, New COF-1 and New COF-2 show higher Q values ​​compared to the COFs in previous studies. st} -1 In other words, the new COF requires less energy for regeneration and has high CO2 / N2 selectivity, making it superior to conventional COFs in terms of CO2 separation and capture capacity.

[0092] The unreacted amino groups (primary amines) present in new COF-1 and new COF-2 can be used for post-synthesis addition of new functional groups. An example is shown below. In this example, the amino groups (primary amines) were modified with acetic anhydride to form amide functional groups. First, cleaned new COF-1 was placed in a mixture of acetic anhydride and acetic acid (1:1, v:v) and heated at 80 °C for 24 hours. The mixture was then returned to room temperature and ultrasonically dispersed for 10 minutes. The resulting precipitate was first subjected to DMA and then to solvent exchange with water, and then held at 80 °C for approximately one day. The mixture was then returned to room temperature, and the appearance of the precipitate in water was observed under an optical microscope (Figure 45).

[0093] Furthermore, the modified sample was subjected to solvent exchange with DMA, followed by solvent exchange with toluene. The crystals were collected on filter paper and dried in vacuum at 80 °C for 12 hours under a 50 sccm flow of dry nitrogen, after which FT-IR measurements were performed (Figure 46). -1 The peak indicates the presence of a C=O bond, which indicates that the unreacted amino groups of the COF of the present invention were used to add and modify the COF with an amide functional group, as intended, to produce a derivative.

[0094] References [1] Zhu, D. & Verduzco, R. Ultralow surface tension solvents enable facile COF activation with reduced pore collapse. ACS Appl. Mater. Interfaces 12, 33121-33127 (2020). [2] Metz, G., Wu, X. L. & Smith, S. O. Ramped-Amplitude cross polarization in magic-angle-spinning NMR. J. Magn. Reson., Ser. A 110, 219-227 (1994). [3] Bennett, A. E., Rienstra, C. M., Auger, M., Lakshmi, K. V. & Griffin R. G. Heteronuclear decoupling in rotating solids. J. Chem. Phys. 103, 6951-6958 (1995). [4] Nuhnena, A. & Janiak, A. A practical guide to calculate the isosteric heat / enthalpy of adsorption via adsorption isotherms in metal-organic frameworks, MOFs. Dalton Trans. 49, 10295-10307 (2020). [5] Myers, A. L. & Prausnitz, J. M. Thermodynamics of mixed-gas adsorption. AlChE J. 11, 121-127 (1965). [6] Hu, Y., Jiang, Y., Li, J., Wang, L., Steiner, M., Neumann, R. F., Luan B. & Zhang, Y. New-generation anion-pillared metal-organic frameworks with customized cages for highly efficient CO2 capture. Adv.Funct. Mater. 33, 2213915 (2023). [7] Nguyen, H. L., Gropp, C. & Yaghi, O. M. Reticulating 1D ribbons into 2D covalent organic frameworks by imine and imide linkages. J. Am. Chem. Soc. 142, 2771-2776 (2020). [8] Steiner, T. Lengthening of the N-H bond in N-H --- N hydrogen bonds. Preliminary structural data and implications of the bond valence concept. J. Chem. Soc. Chem. Commun. 1331-1332 (1995). [9] Prasad, N. & Govil G. Study of geometrical parameters in N-H --- N type of hydrogen bonds. Proc. Indian Acad. Sci. (Chem. Sci.), 89, 253-262 (1980).

[0010] Guo, B., Wu, C., Su, Q., Liu, Z., Li, X., Li, G. & Wu, Q. A Zn-salen based covalent triazine framework as a promising candidate for CO2 capture. Mater. Lett. 221, 236-239 (2018).

[0011] Fu, Y., Wang, Z., Li, S., He, X., Pan, C., Yan, J. & Yu, G. Functionalized covalent triazine frameworks for effective CO2 and SO2 removal. ACS Appl. Mater. Interfaces 10, 36002-36009 (2018).

[0012] Dua, J., Cuia, Y., Liua, Y., Krishnac, R., Yu, Y., Wanga, S., Zhanga, C., Songa, X. & Liang, Z. Preparation of benzodiimidazole-containing covalent triazine frameworks for enhanced selective CO2 capture and separation. Microporous Mesoporous Mater. 276, 213-222 (2019).

[0013] Xiong, X.-H., Zhang, L., Wang, W., Zhu, N.-X., Qin, L.-Z., Huang, H.-F., Meng, L.-L., Xiong, Y.-Y., Barboiu, M., Fenske, D., Hu, P. & Wei, Z.-W. Nitro-decorated microporous covalent organic framework (TpPa-NO2) for selective separation of C2H4 from a C2H2 / C2H4 / CO2 mixture and CO2 capture. ACS Appl. Mater. Interfaces 14, 32105-32111 (2022).

[0014] Li, X., Su, Q., Luo, K., Li, H., Li, G. & Wu, Q. Construction of a highly heteroatom-functionalized covalent organic framework and its CO2 capture capacity and CO2 / N2 selectivity. Mater. Lett. 282, 128704 (2021).

[0015] Mukherjee, S., Das, M., Manna, A., Krishna, R. & Das, S. Newly designed 1,2,3-triazole functionalized covalent triazine frameworks with exceptionally high uptake capacity for both CO2 and H2. J. Mater.Chem. A 7, 1055-1068 (2019).

[0016] Gao, C., Li, J., Yin, S., Sun, J. & Wang, C. Redox-triggered switching in three-dimensional covalent organic frameworks. Nat. Commun. 11, 4919 (2020).

[0017] Gui, B., Liu, X., Cheng Y., Zhang, Y., Chen, P., He, M., Sun, J. & Wang, C. Tailoring the pore surface of 3D covalent organic frameworks via post-synthetic click chemistry. Angew. Chem. Int. Ed. 61, e202113852 (2022).

[0018] Das, P. & Mandal, S. K. In-depth experimental and computational investigations for remarkable gas / vapor sorption, selectivity, and affinity by a porous nitrogen-rich covalent organic framework. Chem. Mater. 31, 1584-1596 (2019).

[0019] Wang, Y., Kang, C., Zhang, Z., Usadi, A. K., Calabro, D. C., Baugh, L. S., Yuan, Y. D. & Zhao, D. Evaluation of Schiff-base covalent organic frameworks for CO2 capture: structure-performance relationships, stability, and performance under wet conditions. ACS Sustainable Chem. Eng. 10, 332-341 (2022).

[0020] Kumar, G., Singh, M., Goswami, R.& Neogi, S. Structural dynamism-actuated reversible CO2 adsorption switch and postmetalation-induced visible light Cα-H photocyanation with rare size selectivity in N-functionalized 3D covalent organic framework. ACS Appl. Mater. Interfaces 12, 48642-48653 (2020).

[0095] [Example 2] 1. New COF-1-N + Preparation of new COF-1-N by treating new COF-1 with CH3I to convert the primary amine in new COF-1 into a quaternary ammonium cation. + In the treatment, new COF-1, CH3I, and DMF were placed in a 2 mL glass vial and heated in a convection oven to prepare new COF-1-N. + The specific preparation conditions were as follows: New COF-1: 5 mg CH3I: 300 μL Solvent: DMF 1 mL Temperature: 50 °C Reaction time: 1 day

[0096] The new COF-1-N obtained + FTIR measurement, PXRD measurement, and SEM observation were performed on the new COF-1. FTIR measurement revealed a signal (2800 cm) of a methyl group generated by the conversion of the primary amine in the new COF-1 to a quaternary ammonium. -1 In the PXRD measurement, there was also a change in the low-angle peak, which indicates a long-period structure, and changes such as the broadening of the interlayer spaces were observed. SEM images confirmed the presence of crystals with open interlayer spaces. This is explained by the fact that the primary amines in new COF-1 were converted into quaternary ammonium cations, causing electronic repulsion between the layers.

[0097] 2. New COF-2-N + Preparation of New COF-1-N + In a similar manner to the preparation method of the new COF-2, new COF-2-N was prepared by treating the new COF-2 with the method described below.+ In the treatment, a 6 mL glass vial was used, the amount of CH3I was 800 μL, the amount of DMF was 4 mL, the reaction temperature was 60 °C, and the reaction time was 2 to 3 days. As a result, new COF-2-N + was successfully dissolved or dispersed in DMF (Figure 47).

[0098] 3. Preparation of new COF-1-NH By treating new COF-1 using the method described below, new COF-1 was converted from the imine bond to a secondary amine to prepare new COF-1-NH. In the treatment, new COF-1, NaBH4, and MeOH were placed in a 100 mL glass vial, and the glass vial was then immersed in an ice bath (a tank of ice water) at 0°C for 12 hours while stirring to obtain new COF-1-NH. The specific preparation conditions were as follows: new COF-1: 50 mg, NaBH4: 100 mg, solvent: MeOH 50 mL, temperature: 0°C, reaction time: 12 hours

[0099] The obtained new COF-1-NH was subjected to FTIR and PXRD measurements. In the FTIR spectrum of new COF-1-NH, the imine bond signal (1620 cm) that was present in new COF-1 was not observed. -1 The signal indicating a secondary amine (around 1607 cm) has disappeared. -1 and 1280 cm -1 In PXRD measurements, the low-angle peak, which indicates a long-period structure, observed in new COF-1 was shifted to a lower angle (longer period) in new COF-1-NH. This peak shift to a lower angle can be interpreted as being caused by the expansion of the COF in the in-plane direction of the layer due to the conversion of the imine (-C=N-) double bond to a secondary amine (-C-NH-) single bond.

[0100] 4. Preparation of new COF-2-NH New COF-2-NH was prepared by treating new COF-2 using the same method as for preparing new COF-1-NH. FTIR and PXRD measurements of the obtained new COF-2-NH yielded results similar to those of new COF-1-NH.

[0101] 5. New COF-1-NH-N + By treating new COF-1-NH with the method described below, both the primary amine and secondary amine in new COF-1-NH were converted into quaternary ammonium cations to prepare new COF-1-NH-N. + In the treatment, new COF-1-NH, CH3I, and DMF were placed in a 2 mL glass vial and heated in a convection oven to prepare new COF-1-NH-N. + The specific preparation conditions were as follows: New COF-1-NH: 10 mg CH3I: 100 μL Solvent: DMF 1 mL Temperature: 60 °C Reaction time: 5 days

[0102] To confirm the intended progress of the reaction, the amount of solid precipitate was compared before and after heating and over time (Figure 48, left). As shown in the figure, the height of the solid precipitate from the bottom of the vial just before heating was about 1 mm, but after heating, the solid precipitate almost disappeared. The amount of precipitate continued to decrease for 1 to 3 days after heating, and by the fourth day onwards, there was almost no precipitate visible to the naked eye.

[0103] 6. New COF-2-NH-N + Preparation of new COF-2-NH by the above new COF-1-NH-N + By treating the new COF-2-NH with a method similar to that used for the preparation of the new COF-2-NH, both the primary and secondary amines in the new COF-2-NH were converted into quaternary ammonium cations. + In the treatment, a 6 mL glass vial was used, the amount of new COF-2-NH was 5 mg, the amount of CH3I was 200 μL, the amount of DMF was 4 mL, and the reaction time was 3 days. + The time course of the amount of solid precipitate was also investigated for new COF-1-NH-N + Similar results were obtained as in the case of (Fig. 49).

[0104] New COF-1-NH-N + and new COF-2-NH-N + The outline of the fabrication method is shown below.

[0105] 7. New COF-1-NH-N + Dispersion of new COF-1-NH-N in DMF in water + The solvent was evaporated using an evaporator. After that, water was added and ultrasonic dispersion was performed to obtain new COF-1-NH-N + was dissolved or dispersed in water (Fig. 50, left). The same treatment was also carried out on new COF-1 (Fig. 50, right). As shown in the figure, new COF-1 remained suspended in the form of particles and did not dissolve or disperse in water, whereas new COF-1-NH-N + As planned, we succeeded in dispersing or dissolving the compound in water.

[0106] 8. New COF-1-NH-N + Filtration of aqueous solution The new COF-1-NH-N prepared above + The aqueous solution was filtered through a porous filter (PTFE filter paper) and then vacuum dried. + The SEM image of the new COF-1-NH-N is shown in Figure 51. As shown in the figure, + A layer of COF-1-NH-N was deposited on the filter. + From the above examples, we have succeeded in forming a filter with molecular-scale selectivity. + A new filter configuration has been invented in which a porous material is coated or deposited on the supporting surface of the porous material.

[0107] 9. New COF-1-NH-N + Dispersion of new COF-1-NH-N in DMF + The solvent was evaporated using an evaporator. Then, DMF was added and ultrasonic dispersion was performed to obtain new COF-1-NH-N + was dissolved or dispersed in DMF. When this dispersion was irradiated with laser light from a laser pointer, light scattering was observed in the light path (Figure 52).

[0108] 10. New COF-1-NH-N + Filtration of the DMF solution of the new COF-1-NH-N prepared above +The DMF solution was filtered through a PTFE filter paper and then vacuum dried. + The SEM image of the new COF-1-NH-N is shown in Figure 53. As shown in the figure, + A layer of COF-1-NH-N was deposited on the filter. + By this method, we succeeded in forming a filter with molecular-scale selectivity. The small particles on the right side of Figure 53 are gold particles formed by gold sputtering to impart conductivity for SEM observation.

[0109] 11. Preparation of New COF-3 In Example 1, New COF-1 and New COF-2 were prepared from tetrahedral building block molecules bearing amino groups and triangular building block molecules bearing aldehyde groups. As described below, a new COF (New COF-3) was successfully created from these building block molecules and building block molecules with an inverse relationship in terms of functional groups and structure, i.e., a triangular building block molecule bearing an amino group (TPB, 1,3,5-tris(4-aminophenyl)benzene) and a tetrahedral building block molecule bearing an aldehyde group (TFS, tetrakis(4-formylphenyl)silane).

[0110] TFS was added to o-DCB and ultrasonicated for 5 minutes to disperse the TFS. Next, AcOH and aniline were dispensed, followed by the addition of a solution of TPB in MeCN. The TFS and TPB reacted to produce new COF-3. The specific preparation conditions were as follows: TFS: 1.79 mg; TPB: 1.87 mg; Aniline: 7.3 μL; AcOH: 60 μL; Solvent: o-DCB 400 μL, MeCN 150 μL; Temperature: 22°C; Reaction time: 8 days.

[0111] The new COF-3 obtained was subjected to FTIR measurement, PXRD measurement, and SEM observation. FTIR measurement confirmed the formation of imine bonds in the new COF-3. PXRD measurement showed that the new COF-3 exhibited a diffraction pattern similar to that of the new COF-1 and new COF-2. These findings indicated that the new COF-3 was also a layered COF. SEM images also revealed the layered structure of this COF. These findings demonstrate that similar layered COFs can be formed using building block molecules in which the aldehyde group is exchanged for an amino group.

[0112] All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety.

Claims

1. A covalent organic framework (COF) characterized by the following (1) to (5): (1) The building block molecules used to generate the covalent organic framework are Tetra building block molecules having functional groups at each vertex of a tetrahedron and Tri building block molecules having functional groups at each vertex of a triangle; (2) The functional groups of the Tetra building block molecules and the Tri building block molecules can form covalent bonds between them through a condensation reaction (also called an addition-elimination reaction, hereinafter the same); (3) The covalent organic framework has a planar network constructed by covalent bonds formed by periodic condensation of the Tetra building block molecules and the Tri building block molecules; (4) The planar networks can be stacked to form layered materials; (5) Three of the four condensed functional groups of the Tetra building block molecules condense with three functional groups of the Tri building block molecules to form covalent bonds, and the remaining functional group remains facing out of the plane of the planar network.

2. The covalent organic framework according to claim 1, characterized in that the covalent bond formed by the periodic condensation of the Tetra building block molecules and the Tri building block molecules is a covalent bond formed between a C atom and a N atom.

3. The covalent organic framework according to claim 1, wherein the remaining functional group is an amino group, an aldehyde group, or a trimethylammonium group.

4. The covalent organic framework according to claim 1, characterized in that the covalent bond formed by the periodic condensation of the Tetra building block molecule and the Tri building block molecule is a covalent bond between a C atom and a N atom, and the remaining functional group is a trimethylammonium group.

5. A solution or dispersion of a covalent organic framework, characterized in that the covalent organic framework according to claim 4 is dissolved or dispersed in a liquid.

6. A method for preparing a film of a covalent organic framework, comprising the steps of pouring a solution or dispersion of the covalent organic framework of claim 5 onto a substrate having holes, thereby depositing the covalent organic framework on the substrate.

7. A gas adsorbent comprising the covalent organic framework of claim 1.

8. A separation membrane comprising the covalent organic framework of claim 1.

9. A drug delivery carrier comprising the covalent organic framework of claim 1.

10. A derivative of the covalent organic framework of claim 1, formed by modifying the unreacted functional groups of the covalent organic framework with another compound through a reaction.

Images