Carbon dioxide scavenging agents, metal-organic structures, and compounds

Abstract

[Problem] To provide a novel carbon dioxide capturing agent and the like whereby it is possible to capture carbon dioxide. [Solution] A carbon dioxide capturing agent containing a metal-organic framework, wherein the metal-organic framework is capable of capturing carbon dioxide and of releasing carbon dioxide, an isolated space is formed in the interior of the metal-organic framework by the three-dimensional structure of the metal-organic framework, the isolated space is a space capable of capturing carbon dioxide and does not normally include channels through which carbon dioxide can pass, and although the three-dimensional structure of the metal-organic framework changes in the process of carbon dioxide being captured within the isolated space and in the process of carbon dioxide being released from the isolated space, the three-dimensional structure of the metal-organic framework when carbon dioxide is captured in the isolated space and the three-dimensional structure of the metal-organic framework when carbon dioxide is not captured in the isolated space are the same.

Description

[Technical Field]

[0001] The present invention relates to a carbon dioxide scavenger, a metal-organic structure usable in the carbon dioxide scavenger, and a compound usable as a ligand for the metal-organic structure. [Background technology]

[0002] In recent years, efforts toward a decarbonized society have made the development of materials for capturing or storing carbon dioxide an urgent necessity.

[0003] Porous network complexes (PCNs), composed of combinations of organic polydentate ligands and metal ions, are attracting attention as promising carbon dioxide scavenging agents due to their high design potential. Numerous PCNs demonstrating carbon dioxide scavenging capabilities have been reported to date (see, for example, Non-Patent Documents 1 and 2). Furthermore, gate-open type MOFs are known as metal-organic frameworks (MOFs) capable of trapping gases. However, in gate-open type MOFs, the volume after trapping gas is larger than the volume before trapping gas. That is, gate-open type MOFs undergo a structural change that causes volume expansion upon gas trapping (see, for example, Non-Patent Document 3). If the structural change of the MOF is large, the low durability of the MOF itself becomes a concern. Also, if the volume expansion of the MOF is large, the low durability of the MOF when it is used as a molded body becomes a concern. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Zhong Li et al,ACS Sustainable Chem.Eng.8,41,15378-15404(2020). [Non-Patent Document 2] Calogero Giancarlo Piscopo et al,ChemPlusChem 85,538-547(2020). [Non-Patent Document 3] Isotope News August 2017 No.752, 12-15. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a novel carbon dioxide scavenging agent capable of capturing carbon dioxide, a metal-organic structure usable in the carbon dioxide scavenging agent, and a compound usable as a ligand for the metal-organic structure. [Means for solving the problem]

[0006] The inventors of the present invention conducted diligent research to solve the above problems and, as a result, found that they could solve the above problems, and completed the present invention having the following gist. In other words, the present invention encompasses the following: [1] A carbon dioxide scavenger containing a metal-organic structure, The aforementioned metal-organic structure is capable of capturing carbon dioxide and desorbing carbon dioxide. Within the metal-organic structure, an isolated space is formed by the three-dimensional structure of the metal-organic structure. The aforementioned isolated space is a space capable of capturing carbon dioxide, and which under normal conditions does not have channels through which carbon dioxide can pass. Although the three-dimensional structure of the metal-organic structure changes during the process in which carbon dioxide is trapped in the isolated space and the process in which carbon dioxide is released from the isolated space, the three-dimensional structure of the metal-organic structure when carbon dioxide is trapped in the isolated space is the same as the three-dimensional structure of the metal-organic structure when carbon dioxide is not trapped in the isolated space. Carbon dioxide scavenging agent. [2] The BET specific surface area of ​​the metal-organic structure measured using N2 is 1 m² 2 A carbon dioxide scavenger as described in [1], which is less than or equal to / g. [3] The carbon dioxide scavenger according to [1] or [2], wherein the metal-organic framework forms an interpenetrated structure in which two frameworks mutually interpenetrate each other. [4] The carbon dioxide scavenger according to any one of [1] to [3], wherein in the metal-organic framework, an element constituting the isolated space and carbon dioxide trapped in the isolated space do not form a chemical bond. [5] The carbon dioxide scavenger according to any one of [1] to [4], wherein the metal-organic framework contains at least one of Group II to Group XIV elements as a constituent element. [6] The carbon dioxide scavenger according to any one of [1] to [5], wherein the metal-organic framework contains a halogen element as a constituent element. [7] The carbon dioxide scavenger according to any one of [1] to [6], wherein the metal-organic framework contains a compound having a nitrogen-containing aromatic heterocycle as a ligand. [8] The carbon dioxide scavenger according to [7], wherein the compound having a nitrogen-containing aromatic heterocycle is a compound represented by the following formula (1).

Chemical Formula

[10] A carbon dioxide scavenger according to any one of [1] to [9], wherein the compositional formula of the metal-organic structure is represented by Cu4I4L, with L as the ligand.

[11] A metal-organic structure containing at least one element from Group II to Group XIV as a constituent element and a compound represented by the following formula (1) as a ligand. [ka] (In the above formula (1), X 11 and X 13 is N and X12 , X 14 and X 15 are CR, or X 12 and X 14 is N and X 11 , X 13 and X 15 are CR, or X 11 and X 15 is N and X 12 , X 13 and X 14 is CR. X 21 and X 23 is N and X 22 , X 24 and X 25 are CR, or X 22 and X 24 is N and X 21 , X 23 and X 25 are CR, or X 21 and X 25 is N and X 22 , X 23 and X 24 is CR. X 31 and X 33 is N and X 32 , X 34 and X 35 are CR, or X 32 and X 34 is N and X 31 , X 33 and X 35 are CR, or X 31 and X 35 is N and X 32 , X 33 and X 34 is CR. X 41 and X 43 is N and X 42 , X 44 and X 45 are CR, or X 42 and X 44 is N and X 41 , X 43 and X 45Is it CR, or X 41 and X 45 is N and X 42 , X 43 and X 44 It is CR. Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom. R 1 ~R 6 Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom.

[12] The metal-organic structure according to

[11] , wherein the compound represented by formula (1) is the compound represented by the following formula (1-1). [ka] (In the above formula (1-1), Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom. R 1 ~R 6Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom.

[13] A metal-organic structure according to

[11] or

[12] , comprising a halogen element as a constituent element.

[14] A metal-organic structure according to any one of

[11] to

[13] , wherein the ligand is L, and the composition formula is Cu4I4L.

[15] The constituent elements include copper, The metal-organic structure according to any one of

[11] to

[14] , wherein the ligand is coordinated to the copper by one of the two nitrogen atoms of the pyrimidine ring of the ligand.

[16] The constituent elements include copper and iodine, The metal-organic structure according to any one of

[11] to

[15] , wherein Cu4I4 exists in the cubane form in the metal-organic structure.

[17] The constituent elements include copper and iodine, In the aforementioned metal-organic structure, Cu4I4 exists in the cubane form. If the ligand is L, the empirical formula is represented as Cu4I4L. The metal-organic structure according to any one of

[11] to

[16] , wherein the ligand is coordinated to the copper by one of the two nitrogen atoms of the pyrimidine ring of the ligand.

[18] A carbon dioxide scavenger containing a metal-organic structure as described in any of

[11] to

[17] .

[19] A compound represented by the following formula (1). [ka] (In the above formula (1), X 11 and X 13 is N and X 12 , X 14 and X15 Is it CR, or X 12 and X 14 is N and X 11 , X 13 and X 15 Is it CR, or X 11 and X 15 is N and X 12 , X 13 and X 14 It is CR. X 21 and X 23 is N and X 22 , X 24 and X 25 Is it CR, or X 22 and X 24 is N and X 21 , X 23 and X 25 Is it CR, or X 21 and X 25 is N and X 22 , X 23 and X 24 It is CR. X 31 and X 33 is N and X 32 , X 34 and X 35 Is it CR, or X 32 and X 34 is N and X 31 , X 33 and X 35 Is it CR, or X 31 and X 35 is N and X 32 , X 33 and X 34 It is CR. X 41 and X 43 is N and X 42 , X 44 and X 45 Is it CR, or X 42 and X 44 is N and X 41 , X 43 and X 45 Is it CR, or X 41 and X45 is N and X 42 , X 43 and X 44 It is CR. Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom. R 1 ~R 6 Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom.

[20] The compound described in

[19] , which is represented by the following formula (1-1). [ka] (In the above formula (1-1), Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom. R 1 ~R 6 Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a novel carbon dioxide scavenging agent capable of capturing carbon dioxide, a metal-organic structure usable in the carbon dioxide scavenging agent, and a compound usable as a ligand for the metal-organic structure. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of a mutually interpenetrating structure in which two frameworks intersect with each other. [Figure 2] This is a schematic diagram of a cubane-type structure. [Figure 3] This is a schematic diagram of the three-dimensional structure of an example of a metal-organic structure of the present invention (without carbon dioxide capture). [Figure 4] This is a schematic diagram of the three-dimensional structure of an example of a metal-organic structure of the present invention (with carbon dioxide capture). [Figure 5A] This is the result of single-crystal X-ray structural analysis of pyrimidine ligands (Lp) (Part 1). [Figure 5B] This is the result of single-crystal X-ray structural analysis of the pyrimidine ligand (Lp) (Part 2). [Figure 6] These are the FT-IR measurement results of the metal-organic structure [Cu4I4Lp] and pyrimidine ligand (Lp) before solvent removal. [Figure 7A] This figure (Part 1) shows the single crystal structure of the metal-organic structure [Cu4I4Lp] before solvent removal. [Figure 7B] This figure (part 2) shows the single crystal structure of the metal-organic structure [Cu4I4Lp] before solvent removal. [Figure 8A] This is another figure (part 1) showing the single crystal structure of the metal-organic structure [Cu4I4Lp] before solvent removal. [Figure 8B] This is another figure (part 2) showing the single crystal structure of the metal-organic structure [Cu4I4Lp] before solvent removal. [Figure 8C] This is another figure (part 3) showing the single crystal structure of the metal-organic structure [Cu4I4Lp] before solvent removal. [Figure 9A]This is yet another figure (part 1) showing the single crystal structure of the metal-organic structure [Cu4I4Lp] before solvent removal. [Figure 9B] This is yet another figure (part 2) showing the single crystal structure of the metal-organic structure [Cu4I4Lp] before solvent removal. [Figure 10] This shows the PXRD measurement results of the metal-organic structure [Cu4I4Lp] before solvent removal. [Figure 11] This is the adsorption isotherm of the metal-organic structure [Cu4I4Lp]. [Figure 12] This figure shows the single crystal structure of the metal-organic structure [Cu4I4Lp] after solvent removal. [Figure 13] This figure shows the single crystal structure of the metal-organic structure [Cu4I4Lp] after CO2 capture. [Figure 14] These are the FT-IR measurement results for the metal-organic structure [Cu4I4Lp] before solvent removal [III], after solvent removal [II], and after CO2 capture [I]. [Modes for carrying out the invention]

[0009] (Carbon dioxide scavenger) The carbon dioxide scavenger of the present invention contains a metal-organic structure. The carbon dioxide scavenger may also be the metal-organic structure itself. Metal-organic structures are capable of capturing carbon dioxide and also capable of releasing carbon dioxide. Within the metal-organic structure, isolated spaces are formed by the three-dimensional structure of the metal-organic structure. An isolated space is a space that can capture carbon dioxide and does not normally have channels through which carbon dioxide can pass. In metal-organic structures, the three-dimensional structure of the metal-organic structure changes during the process in which carbon dioxide is trapped in an isolated space and during the process in which carbon dioxide is released from the isolated space. However, the three-dimensional structure of the metal-organic structure when carbon dioxide is trapped in an isolated space is the same as the three-dimensional structure of the metal-organic structure when carbon dioxide is not trapped in an isolated space.

[0010] Here, "normal state" refers to the state in which the product is placed in air at normal temperature (25°C) and normal pressure (1 atm).

[0011] A channel refers to a passage between one space and another space or the outside, through which carbon dioxide can pass. Whether a passage between a space and another space or the outside allows a molecule to pass through can be determined from the molecule's kinetic diameter and the spatial size of the passage in terms of the molecule's passability. Here, the spatial size of a passage from the perspective of molecular passageability can be determined from the positions of the atoms constituting the passage and the van der Waals radii of the atoms constituting the passage. The space enclosed by the atoms constituting the passage, narrowed by the van der Waals radius from the position of each atom (referred to as the passage space), becomes the passage. If a sphere with a diameter equivalent to the kinetic diameter of a molecule can pass through a passage, then that molecule can pass through the passage. Furthermore, the Kinetic Diameter of gaseous helium is smallest. If a sphere with a diameter equivalent to Diameter (2.57 Å) cannot pass through a passage, then no molecule can pass through that passage. The positions of the atoms constituting the pathways can be determined by single-crystal X-ray diffraction analysis.

[0012] Metal-organic structures are also known as porous coordination polymers (PCPs). Metal-organic structures have a framework. The framework is constructed by ligands bonding to a nodal metal or metal compound via coordinate bonds, and consists of constituent elements and chemical bonds (mainly covalent bonds and coordinate bonds).

[0013] The inventors have discovered a novel metal-organic structure in which, although the three-dimensional structure of the metal-organic structure changes during the process in which carbon dioxide is trapped in an isolated space and the process in which carbon dioxide is released from the isolated space, the three-dimensional structure of the metal-organic structure when carbon dioxide is trapped in an isolated space is the same as the three-dimensional structure of the metal-organic structure when carbon dioxide is not trapped in an isolated space. On the other hand, the novel metal-organic structure discovered by the inventors undergoes a change in its three-dimensional structure during the process of carbon dioxide being trapped in an isolated space and the process of carbon dioxide being released from that isolated space. However, the three-dimensional structure of the metal-organic structure when carbon dioxide is trapped in the isolated space is the same as the three-dimensional structure of the metal-organic structure when carbon dioxide is not trapped in the isolated space (hereinafter, this behavior in the metal-organic structure may be referred to as "no change in three-dimensional structure before and after carbon dioxide trapping"). Therefore, the above-mentioned problem in gate-open type MOFs is less likely to occur. This point is extremely useful when using metal-organic structures.

[0014] Here, "the three-dimensional structure of the metal-organic structure when carbon dioxide is trapped in an isolated space is the same as the three-dimensional structure of the metal-organic structure when carbon dioxide is not trapped in an isolated space" means, for example, that the rate of change between the lattice constants of the crystal structure of the metal-organic structure when carbon dioxide is trapped in an isolated space (a1[Å], b1[Å], c1[Å], α1[°], β1[°], γ1[°]) and the lattice constants of the crystal structure of the metal-organic structure when carbon dioxide is not trapped in an isolated space (a2[Å], b2[Å], c2[Å], α2[°], β2[°], γ2[°]) is within ±10%. This rate of change is preferably within ±5%, more preferably within ±3%, and particularly preferably within ±1%. The rate of change of each lattice constant can be calculated as follows: • Percentage change of a (%) = [(a1-a2) / a1] × 100 • Percentage change of b (%) = [(b1-b2) / b1] × 100 • Percentage change of c (%) = [(c1-c2) / c1] × 100 • Percentage change of α (%) = [(α1 - α2) / α1] × 100 • Percentage change of β (%) = [(β1 - β2) / β1] × 100 • Percentage change of γ (%) = [(γ1-γ2) / γ1] × 100 The lattice constant can be determined by single-crystal X-ray diffraction analysis.

[0015] The inventors believe that a key characteristic of metal-organic structures that do not undergo steric change before and after carbon dioxide capture is that the two frameworks form a mutually penetrating structure in which they penetrate each other. A schematic diagram of the interpenetrating structure is shown in Figure 1 (Christian S. Diercks, Omar M. Yaghi, Science 2017 Vol.355, Issue 6328, eaal158). In the interpenetrating structure of Figure 1, the first framework F1 and the second framework F2 penetrate each other. In other words, the second framework F2 is fitted into the first framework F1. Metal-organic structures form such structures (interpenetrating structures in which two frameworks penetrate each other), and moderate changes in three-dimensional structure occur as the relative positions of the two frameworks change. On the other hand, because the two frameworks penetrate each other, there are limits to the changes in the relative positions of the two frameworks. Therefore, the changes in three-dimensional structure are moderately constrained. The inventors believe that this is a factor that causes a structural change that allows carbon dioxide to pass through the isolated space, while at the same time, the three-dimensional structure of the metal-organic structure when carbon dioxide is trapped in the isolated space can be the same as the three-dimensional structure of the metal-organic structure when carbon dioxide is not trapped in the isolated space.

[0016] Furthermore, the inventors believe that the elastic flexibility of the ligand is an important characteristic of metal-organic structures that do not undergo steric changes before and after carbon dioxide capture. The ligand's structure is not rigid; rather, there are parts (bonds) in the ligand's framework that, while not rotatable, can twist (where a part of the molecule changes its angle relative to the rest), giving the ligand elastic flexibility. This ligand flexibility leads to a change in the three-dimensional structure of the metal-organic structure. And because this flexibility is elastic, it is thought that when the factor causing the change in three-dimensional structure (e.g., pressure) is removed, the metal-organic structure can return to a stable structure. The inventors believe that this is the reason why a change in three-dimensional structure occurs that allows carbon dioxide to pass through the isolated space, while at the same time, the three-dimensional structure of the metal-organic structure when carbon dioxide is trapped in the isolated space can be the same as the three-dimensional structure of the metal-organic structure when carbon dioxide is not trapped in the isolated space. Twisting (where one part of a molecule changes its angle relative to the rest) is thought to be likely to occur, for example, in the carbon-carbon bond between a nitrogen-containing aromatic heterocycle and an aromatic hydrocarbon ring in a ligand. The rotation of this carbon-carbon bond is extremely restricted by the physical proximity of the hydrogen or substituent bonded to the nitrogen-containing aromatic heterocycle and the hydrogen or substituent bonded to the aromatic hydrocarbon ring. Therefore, the twisting originating from this carbon-carbon bond cannot rotate freely like the carbon-carbon single bond in a linear hydrocarbon group. Furthermore, this twisting originating from the carbon-carbon bond is elastic because, when the factor causing the change in stereochemistry (e.g., pressure) is removed, it returns to its original state in an attempt to reduce the physical proximity of the hydrogen or substituent bonded to the nitrogen-containing aromatic heterocycle and the hydrogen or substituent bonded to the aromatic hydrocarbon ring. Furthermore, when an aromatic hydrocarbon ring and a nitrogen-containing aromatic heterocycle are bonded by a carbon-carbon bond, the state in which they lie on the same plane is the most energetically high state, i.e., the most unfavorable state. If bulky substituents are present, the energy barrier can no longer be overcome, and rotation is inhibited. The angle between these planes varies depending on the presence or absence of substituents and the type of substituents. For example, in the metal-organic structure [Cu4I4Lp] shown in the examples herein, the angle between the pyrimidine ring plane and the methyl-substituted benzene ring plane is approximately 70°.

[0017] In the measurement of the specific surface area of ​​a metal-organic structure using N2, the BET specific surface area is, for example, 1 m². 2 The amount is less than or equal to / g. In metal-organic structures having pores capable of capturing carbon dioxide and N2, the BET specific surface area measured using N2 is 1 m². 2 A value of less than / g means that the pores are isolated spaces. The BET specific surface area can be determined by measuring the adsorption isotherm using N2. The adsorption isotherm can be measured using a gas adsorption measuring device (for example, the Microtrac-Bel fully automatic gas adsorption measuring device BELSORP MAX). Details of the measurement method are described in the examples.

[0018] In metal-organic structures, for example, the elements constituting an isolated space and the carbon dioxide trapped within that space do not form chemical bonds. The chemical bonds in this context are covalent bonds, ionic bonds, and hydrogen bonds. Whether or not the elements constituting the isolated space and the carbon dioxide trapped within it form a chemical bond can be determined from the types of elements constituting the isolated space and the size of the isolated space. The size of an isolated space can be determined by calculating the results of single-crystal X-ray structure analysis using the Mercury software at the Cambridge Crystallographic Data Centre (CCDC).

[0019] The metal-organic structure contains, for example, at least one of the Group II to Group XIV elements as constituent elements. Preferably, the Group II to Group XIV elements are Zr, Cd, Ti, Cu, Zn, Fe, Cr, Ni, Co, Mo, Hf, Mg, Al, and Si, and more preferably Cu, Zr, Zn, and Cd. The metal-organic structure may contain, for example, halogen elements as constituent elements. Examples of halogen elements include fluorine, chlorine, bromine, and iodine. The constituent elements referred to here are not the elements that make up the ligands. Metal-organic structures include, for example, compounds having nitrogen-containing aromatic heterocycles as ligands. Examples of nitrogen-containing aromatic heterocycles include pyridine rings and pyrimidine rings. The compositional formula of the metal-organic structure is preferably represented as Cu4I4L, where L is the ligand.

[0020] The compound having a nitrogen-containing aromatic heterocycle is preferably the compound represented by formula (1) described later. Furthermore, the compound represented by formula (1) may be defined in the proviso described later, and X 11 ~X 15 , X 21 ~X 25 , X 31 ~X 35 , and X 41 ~X 45 Regarding X 11 ~X 15 One is N and the other is CR, X 21 ~X 25 One is N and the other is CR, X 31 ~X 35 One is N and the other is CR, X 41 ~X 45 It is also possible that one of them is N and the other is CR. 11 ~X 15 , X 21 ~X 25 , X 31 ~X 35 , and X 41 ~X 45 Regarding X 13 , X 23 , X 33 , and X 43 It may also be a configuration in which one is N and the others are CR. In CR, R is synonymous with the R in the proviso of the compound represented by formula (1) described later.

[0021] As the metal-organic structure, the metal-organic structure of the present invention, described in detail below, is preferred.

[0022] (Metal-organic structure) The metal-organic structure of the present invention contains at least one element from Group II to Group XIV as a constituent element and a compound represented by the following formula (1) as a ligand. Furthermore, the metal-organic structure may contain halogen elements as constituent elements. The constituent elements referred to here are not the elements that make up the ligands.

[0023] The elements of Group II to Group XIV are preferably Zr, Cd, Ti, Cu, Zn, Fe, Cr, Ni, Co, Mo, Hf, Mg, Al, and Si, and more preferably Cu, Zn, and Cd. Examples of halogen elements include fluorine, chlorine, bromine, and iodine.

[0024] The compositional formula of the metal-organic structure of the present invention is represented, for example, by Cu4I4L, where L is the ligand.

[0025] The ligand, for example, coordinates to copper by one of the two nitrogen atoms in the pyrimidine ring of the ligand.

[0026] Cu4I4 exists, for example, in the cubane form in the metal-organic structure of the present invention. A schematic diagram of the cubane-type structure is shown in Figure 2. A Cuban structure is a cube, with either Cu or I at each vertex, and line segments between Cu and I forming edges. Cu and Cu are not adjacent, and neither are I and I. In other words, Cu and Cu exist only on diagonals, and I and I also exist only on diagonals. Because the atoms of Cu and I are of different sizes, the actual structure is not a cube but distorted. ∠Cu-I-Cu is approximately 60°, and ∠I-Cu-I is approximately 110°. Note that L in the diagram represents a ligand.

[0027] An example of the crystalline system in the normal state of the metal-organic structure of the present invention is the tetragonal system. Examples of the space group of the metal-organic structure of the present invention in its normal state include I41 / a.

[0028] Here, a schematic diagram of the three-dimensional structure of an example of the metal-organic structure of the present invention is shown. Figure 3 is a schematic diagram of the three-dimensional structure of an example of the metal-organic structure of the present invention (without carbon dioxide capture). In Figure 3, the first framework L1a, represented by light gray spheres (atoms) and rods (bonds), and the second framework L2a, represented by dark gray spheres (atoms) and rods (bonds), penetrate each other, forming a mutual penetration structure.

[0029] Figure 4 is a schematic diagram of the three-dimensional structure of an example of the metal-organic structure of the present invention (with carbon dioxide capture). In Figure 4, similar to Figure 3, the first framework L1a, represented by light gray spheres (atoms) and rods (bonds), and the second framework L2a, represented by dark gray spheres (atoms) and rods (bonds), penetrate each other, forming an interpenetrating structure. Furthermore, in Figure 4, carbon dioxide is trapped within the isolated space formed by the two frameworks, represented by three spheres (corresponding to C and O, respectively) partially overlapping.

[0030] <Compound represented by formula (1)> Compounds represented by formula (1) are also subject to the present invention.

[0031] [ka] (In the above formula (1), X 11 and X 13 is N and X 12 , X 14 and X 15 Is it CR, or X 12 and X 14 is N and X 11 , X 13 and X 15 Is it CR, or X 11 and X 15 is N and X 12 , X 13 and X 14 It is CR. X 21 and X 23 is N and X 22 , X 24 and X 25 Is it CR, or X 22 and X 24 is N and X 21 , X 23 and X 25 Is it CR, or X 21 and X 25 is N and X 22 , X 23 and X 24 It is CR. X 31 and X 33 is N and X 32 , X 34 and X 35 Is it CR, or X 32 and X 34 is N and X 31 , X 33 and X 35 Is it CR, or X 31 and X 35 is N and X 32 , X 33 and X 34 It is CR. X 41 and X 43 is N and X 42 , X 44 and X 45 Is it CR, or X 42 and X 44 is N and X 41 , X 43 and X 45 Is it CR, or X 41 and X 45 is N and X 42 , X 43 and X 44 It is CR. Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom. R 1 ~R 6 Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom.

[0032] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.

[0033] The alkyl group and the alkyloxy group may be linear, branched, or cyclic. The number of carbon atoms in the linear and branched alkyl groups is preferably 1 to 30, more preferably 1 to 12, and particularly preferably 1 to 4. The number of carbon atoms in the cyclic alkyl group is preferably 3 to 30, more preferably 3 to 12, and particularly preferably 3 to 10. Note, R 1 ~R 6 When the alkyl group is an alkyl group or an alkyloxy group, the alkyl group in the alkyl group and alkyloxy group is preferably linear in order to impart appropriate steric hindrance to the benzene ring.

[0034] Examples of alkyl groups include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, 3,7-dimethyloctyl group, and n-lauryl group. Among these, methyl group, ethyl group, n-propyl group, iso-propyl group, and n-butyl group are preferred.

[0035] The number of halogen atoms in an alkyl group substituted with halogen atoms is not particularly limited. Examples of alkyl groups substituted with halogen atoms include trifluoromethyl, pentafluoroethyl, perfluorobutyl, perfluorohexyl, and perfluorooctyl groups.

[0036] Examples of alkyloxy groups include methyloxy group, ethyloxy group, n-propyloxy group, iso-propyloxy group, n-butyloxy group, iso-butyloxy group, tert-butyloxy group, n-pentyloxy group, n-hexyloxy group, cyclohexyloxy group, n-heptyloxy group, n-octyloxy group, 2-ethylhexyloxy group, n-nonyloxy group, n-decyloxy group, 3,7-dimethyloctyloxy group, and lauryloxy group. Among these, methyloxy group, ethyloxy group, n-propyloxy group, iso-propyloxy group, and n-butyloxy group are preferred.

[0037] The number of halogen atoms in an alkyloxy group substituted with halogen atoms is not particularly limited. Examples of alkyloxy groups substituted with halogen atoms include trifluoromethyloxy group, pentafluoroethyloxy group, perfluorobutyloxy group, perfluorohexyloxy group, perfluorooctyloxy group, methyloxymethyloxy group, and 2-methyloxyethyloxy group.

[0038] R, and R1 ~R 6 The aryl group may be unsubstituted. The aryl group may be substituted with a halogen atom. The aryl group may be substituted with a halogen atom or an alkyl group. The aryl group may be substituted with a halogen atom or an alkyloxy group. Examples of (unsubstituted) aryl groups include phenyl, 1-naphthyl, 2-naphthyl, 1-anthracenyl, 2-anthracenyl, and 9-anthracenyl groups. Examples of aryl groups substituted with halogen atoms include the pentafluorophenyl group. Examples of aryl groups substituted with alkyl groups that may be substituted with halogen atoms include C1-C12 alkylphenyl groups (where "C1-C12" means having 1 to 12 carbon atoms; the same applies hereafter). Examples of aryl groups substituted with alkyloxy groups, which may also be substituted with halogen atoms, include C1-C12 alkyloxyphenyl groups. An aryl group is an atomic group obtained by removing one hydrogen atom from an aromatic hydrocarbon. These aromatic hydrocarbons include those with fused rings, and those in which two or more independent benzene rings and / or fused rings are directly bonded or via a group such as vinylene.

[0039] R is preferably a hydrogen atom, a halogen atom, a C1-C3 alkyl group which may be substituted with a halogen atom, or a C1-C3 alkyloxy group which may be substituted with a halogen atom, with a hydrogen atom being more preferred.

[0040] R 1 ~R 6 Preferably, the members are hydrogen atoms, halogen atoms, C1-C3 alkyl groups which may be substituted with halogen atoms, and C1-C3 alkyloxy groups which may be substituted with halogen atoms, with C1-C3 alkyl groups which may be substituted with halogen atoms being more preferred.

[0041] X 11 ~X 15 , X 21 ~X 25 , X 31 ~X 35 , and X 41 ~X 45 For example, the following combinations can be given: (i):X 11 , X 13 , X 21 , X 23 , X 31 , X 33 , X 41 , and X 43 is N and X 12 , X 14 , X 15 , X 22 , X 24 , X 25 , X 32 , X 34 , X 35 , X 42 , X 44 , and X 45 This is a combination that results in a CR (Critical Ratio). (ii):X 12 , X 14 , X 22 , X 24 , X 32 , X 34 , X 42 , and X 44 is N and X 11 , X 13 , X 15 , X 21 , X 23 , X 25 , X 31 , X 33 , X 35 , X 41 , X 43 , and X 45 This is a combination that results in a CR (Critical Ratio). (iii):X 11 , X 15 , X 21 , X 25 , X 31 , X 35 , X 41 , and X 45 is N and X 12 , X 13, X 14 , X 22 , X 23 , X 24 , X 32 , X 33 , X 34 , X 42 , X 43 , and X 44 This is a combination that results in a CR (Critical Ratio). Among these, combination (ii) is preferred because it is easier to obtain a regular three-dimensional structure. That is, the compound represented by formula (1) is preferably the compound represented by the following formula (1-1).

[0042] [ka] (In the above formula (1-1), Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom. R 1 ~R 6 Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom.

[0043] <<Method for producing the compound represented by formula (1)>> The method for producing the compound represented by formula (1) is not particularly limited. For example, it can be produced according to the synthesis reaction shown in the following scheme.

[0044] [ka] (In formula (1A), Y1 ~Y 4 It is a halogen atom. In equations (1A) and (1C), R 1 ~R 6 R in equation (1) 1 ~R 6 It is synonymous with [the above]. In formula (1B) and formula (1C), X 1 ~X 5 X in equation (1) 11 ~X 15 , X 21 ~X 25、 X 31 ~X 35 , and X 41 ~X 45 (This is synonymous with...)

[0045] The synthesis reaction in the above scheme is the so-called Suzuki-Miyaura coupling reaction. Examples of palladium catalysts used in the reaction include [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (PdCl2(dppf)), tetrakis(triphenylphosphine)palladium (Pd(PPh3)4), bis(triphenylphosphine)dichloropalladium (Pd(PPh3)2Cl2), bis(benzylideneacetone)palladium (Pd(dba)2), tris(benzylideneacetone)dipalladium (Pd2(dba)3), bis(tritert-butylphosphine)palladium (Pd(Pt-Bu3)2), palladium acetate (Pd(OAc)2), and chloro[(tri-tert-butylphosphine)-2-(2-aminobiphenyl)]palladium(II) ((tBu3P)Pd G2). These catalysts may be used with known appropriate ligands. The amount of catalyst used may be a so-called catalytic amount, preferably 20 mol% or less relative to the compound represented by formula (1B), and particularly preferably 10 mol% or less. Furthermore, when a ligand is used, its amount may be a so-called catalytic amount, preferably 20 mol% or less relative to the compound represented by formula (1B), and particularly preferably 10 mol% or less.

[0046] Furthermore, bases are also used in the aforementioned synthesis reaction. Examples of such bases include hydroxides, alkoxides, fluoride salts, carbonates, phosphates, and fluoride salts. Examples of hydroxides include sodium hydroxide, potassium hydroxide, and cesium hydroxide. Examples of alkoxides include tert-butoxysodium and tert-butoxypotassium. Examples of fluoride salts include lithium fluoride, potassium fluoride, and cesium fluoride. Examples of carbonates include lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate, and potassium bicarbonate. Examples of phosphates include potassium phosphate. Examples of amines include trimethylamine, triethylamine, diisopropylamine, n-butylamine, and diisopropylethylamine. Of these, from the viewpoint of efficiently obtaining the target product, the base is preferably carbonates or phosphates, and more preferably potassium carbonate or cesium carbonate. The amount of base used is preferably 1 to 20 mol, and more preferably 2 to 10 mol, per 1 mol of formula (1B).

[0047] The solvent used in the aforementioned synthesis reaction is not particularly limited as long as it does not adversely affect the reaction, but specific examples include aliphatic hydrocarbons, halogenated aliphatic hydrocarbons, aromatic hydrocarbons, ethers, amides, lactams, lactones, alcohols, urea derivatives, sulfoxides, and water. Examples of aliphatic hydrocarbons include pentane, n-hexane, n-octane, n-decane, and decalin. Examples of halogenated aliphatic hydrocarbons include chloroform, dichloromethane, dichloroethane, and carbon tetrachloride. Examples of aromatic hydrocarbons include benzene, nitrobenzene, toluene, o-xylene, m-xylene, p-xylene, and mesitylene. Examples of ethers include diethyl ether, diisopropyl ether, tert-butyl methyl ether, tetrahydrofuran (THF), dioxane, 1,2-dimethoxyethane, and 1,2-diethoxyethane. Examples of amides include N,N-dimethylformamide (DMF) and N,N-dimethylacetamide. Examples of lactams include N-methylpyrrolidone. Examples of lactones include γ-butyrolactone. Examples of alcohols include methanol, ethanol, and propanol. Examples of urea derivatives include N,N-dimethylimidazolidinone and tetramethylurea. Examples of sulfoxides include dimethyl sulfoxide and sulfolane, and nitriles (acetonitrile, propionitrile, butyronitrile, etc.). These may be used individually or in combination of two or more types.

[0048] The amounts of the compound represented by formula (1A) and the compound represented by formula (1B) used in the charge are preferably 4 to 10 moles, and more preferably 4.2 to 10 moles, of the compound represented by formula (1B) for every 1 mole of the compound represented by formula (1A), in order to ensure that the cyclization reaction proceeds efficiently.

[0049] The reaction temperature for the aforementioned synthesis reaction is appropriately set within the range from the melting point to the boiling point of the solvent, taking into consideration the type and amount of raw material compounds and catalysts used, but is usually around 0 to 200°C, and preferably 20 to 100°C. Furthermore, the reaction time for the aforementioned synthesis reaction cannot be specified in general terms as it varies depending on the raw material compounds used and the reaction temperature, but it is usually around 1 to 72 hours.

[0050] The aforementioned synthesis reaction is preferably carried out with nitrogen circulating in the reaction vessel.

[0051] <Method for manufacturing metal-organic structures> The method for producing metal-organic structures is not particularly limited, and known methods for producing MOFs can be employed. Examples include one-pot synthesis methods (e.g., self-assembly, solvothermal, microwave irradiation, ionothermal, high-throughput, etc.), stepwise synthesis methods (e.g., metal-organic node structure precursor complex method, complex ligand method, in-situ sequential synthesis method, post-synthesis modification method, etc.), sonochemical synthesis methods, and mechanochemical synthesis methods. Among these methods, the solvothermal method is preferred because it yields stable thermodynamic products. The production of metal-organic structures using the solvothermal method can be carried out by referring, for example, to the literature (Shi-Bin Ren, et al. CrystEngComm, 2009, 11, 1834-1836).

[0052] The following describes an example of a method for producing a metal-organic structure containing the compound represented by formula (1), copper, and iodine using the solvothermal method. In the solvothermal method, for example, a mixture of the compound represented by formula (1), copper(I) iodide, potassium iodide, and a solvent is heated. Potassium iodide is used to improve the solubility of CuI in the solvent. Therefore, depending on the type of solvent and ligand, potassium iodide may not be used.

[0053] When manufacturing a metal-organic structure, the mixing ratio of the compound (L) represented by formula (1) to copper(I) iodide (CuI) is not particularly limited, but a molar ratio (L:CuI) of 1:4 to 1:10 is preferred, and 1:4 to 1:6 is more preferred. The amount of potassium iodide used when manufacturing metal-organic structures is not particularly limited, but it is preferably 10 to 100 moles, and more preferably 30 to 80 moles, per mole of copper(I) iodide.

[0054] When manufacturing metal-organic structures, modulators may be used to promote crystallization as needed. Examples of modulators include triphenylphosphine, pyridinium hydrochloride, and isoquinoline. The amount of modulator used when manufacturing metal-organic structures is not particularly limited, but 0.5 to 10 equivalents, and more preferably 1 to 5 equivalents, is preferred relative to the compound represented by formula (1).

[0055] Examples of solvents include, but are not limited to, N,N-dimethylformamide (DMF), N,N-diethylformamide (DEF), acetonitrile, formic acid, acetic acid, methanol, ethanol, water, and mixtures of two or more of these solvents. Among these, a mixed solvent of acetonitrile, ethanol, and water is preferred.

[0056] The amount of solvent used when manufacturing metal-organic structures is not particularly limited.

[0057] During heating, the raw material solution may be placed in any sealed container, or the heating may be carried out while refluxing the raw material solution.

[0058] The heating temperature is not particularly limited; for example, it may be 100°C or higher, or 120°C or higher, from the viewpoint of increasing reactivity, and may be 150°C or lower from the viewpoint of preventing vapor leakage during the reaction.

[0059] The heating time is not particularly limited and can be adjusted as appropriate according to the heating temperature. The heating time may be 6 hours or more, 10 hours or more, 12 hours or more, 18 hours or more, 24 hours or more, 30 hours or more, 36 hours or more, 42 hours or more, 48 hours or more, 54 hours or more, or 60 hours or more, from the viewpoint of completely completing the reaction, or it may be 96 hours or less, 84 hours or less, 72 hours or less, 60 hours or less, 48 ​​hours or less, 24 hours or less, 12 hours or less, or 10 hours or less.

[0060] Furthermore, after the reaction is complete, the obtained product may be subjected to appropriate post-treatment.

[0061] As a post-treatment, for example, the obtained product may be filtered. Alternatively, if necessary, a poor solvent may be added to the filtrate obtained by filtration, and the mixture may be dispersed at room temperature or by heating as appropriate before being filtered again. The poor solvent may be any solvent in which the target metal-organic structure is poorly soluble, such as water, acetonitrile, hexane, ethanol, or dimethylformamide. The heating temperature may be, for example, 40°C or higher, 50°C or higher, 60°C or higher, 70°C or higher, or 80°C or higher, or 100°C or lower, 90°C or lower, or 80°C or lower. The heating time may be, for example, 1 hour or more, 2 hours or more, 6 hours or more, 10 hours or more, or 12 hours or more, or 24 hours or less, or 16 hours or less.

[0062] Furthermore, the target metal-organic structure can be obtained by appropriately drying the filtrate obtained by filtration or refiltration. Here, drying may be carried out under normal pressure or under reduced pressure, but it is preferable to carry it out under reduced pressure from the viewpoint of improving efficiency. The drying temperature may be, for example, 20°C or higher, 25°C or higher, 40°C or higher, 50°C or higher, or 60°C or higher, or 100°C or lower, 90°C or lower, 80°C or lower, or 60°C or lower. The drying time may be, for example, 1 hour or more, 2 hours or more, 6 hours or more, 10 hours or more, or 12 hours or more, or 24 hours or less, or 16 hours or less.

[0063] <Application> While there are no particular limitations on the applications of metal-organic structures, carbon dioxide scavengers are preferred due to their excellent carbon dioxide scavenging capabilities.

[0064] Furthermore, carbon dioxide scavenging agents can be suitably used in carbon dioxide storage systems capable of storing carbon dioxide. [Examples]

[0065] The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples.

[0066] <NMR Measurement Conditions> 1 1H-NMR spectra (400 MHz) and 13 13C-NMR spectra (400 MHz) were measured using a JNM-ECA400II from JEOL. The measurement sample was dissolved in deuterated chloroform (CDCl3) added with tetramethylsilane (TMS). Chemical shifts were derived with TMS as the reference (δ 0.0 ppm).

[0067] <Single-Crystal X-ray Structure Analysis Conditions> Single-crystal X-ray diffraction data for crystals of the pyrimidine ligand (Lp) and crystals of the metal-organic framework [Cu4I4Lp] containing a solvent (MeCN: acetonitrile) in the pores were measured using a VariMax with Saturn X-ray structure analyzer from Rigaku. Using a Rigaku GNNP low-temperature cooling device, the single crystal was cooled by nitrogen spraying at 123 K. The irradiated X-ray was MoKα radiation (λ = 0.71075 Å) extracted by a graphite monochromator, and the detector was a two-dimensional CCD detector. The measured diffraction data were analyzed using Rigaku's software CrysAlisPro. Single-crystal X-ray diffraction data for (i) crystals of the metal-organic framework [Cu4I4Lp] from which the solvent in the pores has been removed and (ii) crystals of the metal-organic framework [Cu4I4Lp] that have captured CO2 were measured at BL-5A of the Photon Factory (PF), Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK). The single crystal was cooled to 90 K by a Rigaku CryoCooler, irradiated with synchrotron radiation (λ = 0.7500 Å), and the diffraction pattern was detected by a Dectris Pilatus3 S6M. The measured diffraction data were integrated by the software XDS. The CO2-captured crystals were immersed in oil for measurement immediately after being taken out from the CO2 atmosphere into air.

[0068] <Gas adsorption measurement conditions> For the measurement of adsorption and desorption isotherms related to the capture and desorption of nitrogen (77K and 298K) and carbon dioxide (273K and 298K), a fully automated gas adsorption analyzer, BELSORP MAX, was used. The sample was ground in a mortar, and approximately 60 mg was placed in a glass measuring container and attached to the analyzer. The container was evacuated using a rotary pump and a turbomolecular pump, and the solvent in the pores was removed by heating at 473K for 12 hours at a pressure of 1 kPa or less. The amount of adsorption (amount of gas captured) was measured using a constant-volume gas adsorption method without removing the container from the apparatus. This method involves introducing a constant volume of gas into the measuring container and calculating the amount of adsorption (amount of gas captured) by detecting changes in the gas pressure. By gradually increasing the amount of gas, an adsorption isotherm was created, and by reducing the pressure by vacuuming, a desorption isotherm related to gas desorption was obtained. After heating at 473K for 2 hours at 1kPa or less, the measuring container was removed from the apparatus, and the mass of the sample (adsorbate) after solvent removal was determined by weighing with a precision balance. Furthermore, the measurement temperature was maintained by filling a Dewar flask with liquid nitrogen at 77K, and by circulating antifreeze in a water bath using an open-system cooling circulator at 273K or 298K. The experimental results were analyzed using the analysis program BEL MASTER. TM I used it.

[0069] <Infrared absorption spectrum> Infrared absorption spectroscopy is measured by Thermo Fisher Scientific (thermo Nicolet Fourier Transform Infrared Spectrophotometer (Fisher Scientific) TM iS TM The procedure was performed using a liquid nitrogen-cooled MCT-A detector and measured by diffuse reflectance. The sample was diluted with potassium bromide (KBr), and KBr was used as the background.

[0070] <Powder X-ray Diffraction (PXRD) Measurement> A Rigaku fully automatic multi-purpose X-ray diffractometer SmartLab was used for powder X-ray diffraction measurement. At room temperature, the powder sample was irradiated with CuK characteristic X-rays (λ=1.5418Å), and the diffraction pattern was detected while rotating the sample with a D / teX Ultra (1D) detector.

[0071] <Elemental Analysis> An Elementar macro organic elemental analyzer vario MICRO cube was used for elemental analysis.

[0072] (Example 1) The synthesis of the pyrimidine ligand (Lp) was carried out according to the following synthesis scheme.

[0073]

Chemical Formula

[0074] <Synthesis of 2,2’,4,4’,6,6’-hexamethyl-1,1’-biphenyl> Iron(III) chloride hexahydrate (59 g, 0.090 mol) was added to mesitylene (100 mL, 0.18 mol) in a three-necked flask, and the mixture was stirred for 4 hours under a nitrogen atmosphere. The obtained reaction solution was quenched by pouring it into ice water, then transferred to a separatory funnel. The organic layer was collected, washed twice with water, and dried over sodium sulfate. This was transferred to a 100 mL flask, and mesitylene was distilled off by vacuum distillation. When the residue after distillation was cooled with ice water, crystals precipitated. The crystals were collected by suction filtration and washed with acetone to obtain a pale yellow powder. The yield was 12%.

[0075] 1 H NMR (JEOL 400MHz, CDCl3, TMS standard): δ6.93(s,4H,Ha), 2.31(s,6H,Hb), 1.85(s,12H,Hc)

Chemical Formula

[0076] <Synthesis of 3,3’,5,5’-tetraiodo-2,2’,4,4’,6,6’-hexamethyl-1,1’-biphenyl> To a 300 mL flask containing 2,2’,4,4’,6,6’-hexamethyl-1,1’-biphenyl (2.0 g, 8.5 mmol), iodine (3.5 g, 13.6 mmol), and periodic acid (1.6 g, 6.8 mmol) was added a mixed solvent of acetic acid (120 mL), water (24 mL), and sulfuric acid (3.6 mL), followed by heating under reflux at 90°C for 3 days. The resulting mixture was poured into water, and a solid precipitate was collected by suction filtration and washed with water. The pink solid was dissolved in chloroform (100 mL), the solution was washed with saturated aqueous sodium thiosulfate, and iodine was removed by liquid separation. The organic layer was dried over magnesium sulfate, and an orange solid was obtained by drying under reduced pressure. The solid was washed with ethyl acetate, and the target product as a white powder was obtained by suction filtration. The yield was 71%.

[0077] 1 H NMR (JEOL 400 MHz, CDCl3, TMS standard): δ 3.03 (s, 6H, Ha), 2.03 (s, 12H, Hb)

Chemical Formula

[0078] <Synthesis of (5,5’,5’’,5’’’-(2,2’,4,4’,6,6’-hexamethyl-[1,1’-biphenyl]-3,3’,5,5’-tetrayl)tetra-pyrimidine) (pyrimidine ligand (Lp)) 3,3',5,5'-tetraiodo-2,2',4,4',6,6'-hexamethyl-1,1'-biphenyl (0.52 g, 0.70 mmol), 5-pyrimidylboronic acid (0.41 g, 3.3 mmol), tetrakistriphenylphosphine palladium (0.24 g, 0.22 mmol), and potassium carbonate (2.84 g, 21 mmol) were added to a 50 mL Schlenk tube, and the reaction chamber was replaced with nitrogen by alternating vacuum evacuation and nitrogen flow three times. Toluene (30 ml), degassed by bubbling nitrogen gas, ethanol (20 mL), and distilled water (10 mL) were added, and the mixture was heated under reflux at 80°C for 2 days under a nitrogen flow. The solvent was removed by vacuum drying, and the solid was dissolved in chloroform and distilled water. The organic layer was separated by liquid-liquid extraction and washed with saturated brine. The organic layer was dried over magnesium sulfate and then vacuum-dried to obtain the crude product. The crude product was dissolved in a small amount of chloroform and purified by silica gel column chromatography using ethyl acetate / triethylamine = 100 / 1 (volume ratio) as the developing solvent. The resulting product was a white powder with a yield of 69%.

[0079] 1 H NMR(JEOL 400MHz CDCl3, TMS standard): δ9.25(s,4H,Ha), 8.64(s,8H,Hb), 1.75(s,6H,Hc), 1.72(s,12H,Hd), [ka]

[0080] 13 C NMR(JEOL 400MHz CDCl3, TMS standard): δ157.8(A), 157.3(B), 133.6-138.7(CG), 20.0(H), 18.9(I) [ka]

[0081] Elemental analysis. Calcd for [C 34 H 30 N8·0.25CH3COOC2H5]:C,73.40;H,5.63;N,19.56. Found:C,73.40;H,5.54;N,19.34.

[0082] <Single-crystal X-ray structural analysis> Pyrimidine ligands (Lp) were dissolved in chloroform in a vial, covered with Kimwipes, and the chloroform was evaporated for about half a day to obtain single crystals of pyrimidine ligands (Lp). We successfully analyzed the single crystal structure from diffraction by measuring the micro-single-crystal X-ray structure of the crystal using a Rigaku VariMax with Saturn X-ray diffraction analyzer. The results are shown in Table 1 below.

[0083] [Table 1]

[0084] The results of single-crystal X-ray structural analysis are shown in Figures 5A and 5B. Figure 5A shows the unit cell, and Figure 5B shows the structure of a single molecule. The single-crystal structure also confirmed that the desired compound was obtained. Furthermore, the dihedral angle of the two central aromatic rings was measured to be 92.15°, indicating that they are approximately orthogonal. This revealed that a ligand similar to d-symmetry was obtained.

[0085] (Example 2) <Synthesis of metal-organic structures [Cu4I4Lp]> To a PTFE sample decomposition vessel containing pyrimidine ligand (Lp) (11 mg, 0.020 mmol), copper(I) iodide (19 mg, 0.10 mmol), potassium iodide (0.83 g, 5.0 mmol), and triphenylphosphine (5.2 mg, 0.020 mmol), acetonitrile (5.4 mL), distilled water (3.6 mL), and ethanol (1 mL) were added sequentially, followed by heating in an oven at 140°C for 64 hours. After heating, the temperature was slowly lowered inside the oven, and the mixture was taken out of the oven after more than half a day. The precipitate was collected by suction filtration and washed with dimethylformamide, water, and acetonitrile to obtain yellow prismatic crystals. The solid obtained in this step is a mixture. The solid was immersed in a mixed liquid of 4 mL of dichloromethane and 3 mL of dibromomethane, and only the precipitated crystals were collected to obtain pure metal-organic framework [Cu4I4Lp]. The yield was 58% based on the ligand. Elemental analysis. Calcd for{Cu4I4[C 34 H 30 N8(Lp)]·2.21(CH3CN)·1.17(C2H5OH)}:C,33.53;H,3.01;N,9.75. Found:C,33.53;H,2.76;N,9.75.

[0086] <Characterization before solvent (acetonitrile) removal> Acetonitrile is present in the pores of the as-synthesized metal-organic framework [Cu4I4Lp]. In this state, FT-IR measurement, single-crystal X-ray structural analysis, PXRD measurement, and adsorption isotherm measurement were performed.

[0087] <<FT-IR Measurement>> Solid crystals of the metal-organic framework [Cu4I4Lp] were measured with an FT-IR spectrophotometer (Nicolet TM iS TM 50 FT-IR). The results are shown in Figure 6 together with the results for the pyrimidine ligand (Lp). Note that these results are obtained before removing the solvent (acetonitrile) from the crystals. Comparing the IR spectra of pyrimidine ligands (Lp) and metal-organic structures [Cu4I4Lp], the network shows 2200 cm⁻¹. -1 A new peak ([A]) was observed in the vicinity. This is thought to be due to the stretching and contracting of C≡N bonds and is presumed to originate from acetonitrile present in isolated spaces (pores).

[0088] <<Single-crystal X-ray structural analysis>> The single crystals obtained by the above method were measured using a micro-single-crystal X-ray structure analyzer (Rigaku VariMax with Saturn), and the crystal structure was successfully analyzed from diffraction. Details of the analysis results are shown in Table 2. Note that these results were obtained before removing the solvent (acetonitrile) from the crystal.

[0089] [Table 2]

[0090] The single-crystal X-ray structural analysis results of the obtained metal-organic structure [Cu4I4Lp] are shown in Figures 7A-7B, 8A-8C, and 9A-9B.

[0091] The metal-organic structure [Cu4I4Lp] had a cubane-type metal connector. The cubane-type connector, like the ligand, had a four-coordinate diamond structure, and the overall structure formed a three-dimensional diamond structure. Disordered acetonitrile was present as a solvent within the pores. The packing structure is shown in Figures 8A to 8C; the solvent is not shown, indicating the presence of pores wherever the solvent is present. Furthermore, this structure exhibits a mutual penetration structure where two frameworks penetrate each other. Calculations of the pore size using CCDC's Mercury method revealed that the pores were spaces measuring 5.4 Å × 4.9 Å × 4.9 Å with a porosity of 12%. Furthermore, the passages between these spaces and other spaces were too small for a sphere with a diameter equivalent to the kinetic diameter of gaseous helium (2.57 Å) to pass through. Therefore, in the obtained metal-organic structure [Cu4I4Lp], it appears that there are no passages through which matter can pass between pores or between pores and the outside. In other words, the pores in the obtained metal-organic structure [Cu4I4Lp] were isolated spaces. This is thought to be due to the bulky structure of the ligands and the interpenetrating structure of the two frameworks.

[0092] < <pxrd>> Powder X-ray diffraction (PXRD) measurements were performed on the metal-organic structure [Cu4I4Lp]. The results are shown in Figure 10. Note that these results were obtained before removing the solvent (acetonitrile) from the crystal. The PXRD pattern is shown in Figure 10 and closely matches the simulation from the single-crystal structure using Mercury for CCDC. The absence of other peaks indicates that a single structure was obtained.

[0093] <<Gas adsorption isotherms>> The adsorption isotherm for gas capture of the metal-organic structure [Cu4I4Lp] was determined. The results are shown in Figure 11. Note that these results were obtained after removing the solvent (acetonitrile) from the crystal. The solvent was removed by the procedure used for gas adsorption measurement (vacuuming the container with a rotary pump and a turbomolecular pump, and heating at 473K for 12 hours at a pressure of 1 kPa or less). Adsorption isotherms revealed that the metal-organic structure [Cu4I4Lp] did not capture nitrogen gas, but specific capture of CO2 was observed. Hysteresis was also observed during the capture and desorption of CO2. It is generally understood that pores do not capture nitrogen molecules with a larger kinetic diameter, as they are isolated spaces connected to the outside only by passages that spheres with a diameter equivalent to the kinetic diameter of gaseous helium (2.57 Å) cannot pass through. On the other hand, the capture and desorption of CO2 suggests that the three-dimensional structure of the metal-organic structure [Cu4I4Lp] was altered by CO2, creating channels through which CO2 could pass.

[0094] <Characterization after removal of solvent (acetonitrile)> After removing acetonitrile from the pores of the metal-organic structure [Cu4I4Lp], single-crystal X-ray structural analysis and FT-IR measurements were performed. The FT-IR measurement results will be explained in the section on characterization after CO2 capture, which will be described later.

[0095] <<Method for Solvent Removal>> In the adsorption isotherm measured using BELSORP MAX, it was confirmed that by heating at 200°C for 12 hours or more under 1 kPa, the powdered metal-organic framework [Cu4I4Lp] exhibits adsorption properties for capturing gas, that is, the solvent has been removed. Therefore, in order to remove the solvent in the single crystal state, one spatula scoop of single crystals of the metal-organic framework [Cu4I4Lp] was placed into a 10 mL ampoule tube, and the inside of the ampoule tube was evacuated with a rotary pump for 1 hour. The ampoule tube was sealed under vacuum, and heated in an oven at 240°C for 14 hours.

[0096] <<Single-Crystal X-ray Structure Analysis>> The measurement was performed at BL-5A of the Photon Factory (PF), Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK). The ampoule tube was transported in a sealed state, and immersed in oil immediately after the ampoule tube was opened. Therefore, the measurement was performed in air. Details of the analysis results are shown in Table 3. Note that these results are those obtained after removing the solvent (acetonitrile) from the crystal.

[0097]

Table 3

[0098] The results of single-crystal X-ray structure analysis of the metal-organic framework [Cu4I4Lp] in the absence of acetonitrile are shown in Figure 12. Single-crystal X-ray structure analysis confirmed that the single crystal after vacuum heating hardly retains any solvent. It was also found that the point group of the crystal structure did not change even after solvent removal, and almost no change in the size of the unit cell was observed, thus the structure was maintained.

[0099] <Characterization after CO2 Capture> After CO2 was adsorbed onto the metal-organic framework [Cu4I4Lp], single-crystal X-ray structure analysis and FT-IR measurement were performed.

[0100] <<CO2 Capture Method>> BELSORP MAX was used for CO2 capture. Two spatula loads of single crystals, from which the solvent was removed by vacuum heating, were added to the measurement cell of BELSORP. By the same procedure as that for measuring adsorption isotherms, the sample was heated at 200°C below 1 kPa for 12 hours. After heating, the inside of the cell was evacuated and purged with CO2. The cell was filled with CO2 and left to stand for one day. The single crystals were taken out from the cell and transferred to a 5 mL vial. Using a commercially available CO2 spray, CO2 was blown into the vial, and the lid was immediately closed to store the crystals under high-concentration CO2.

[0101] <<Single-Crystal X-ray Structure Analysis>> Measurements were performed at BL-5A of the Photon Factory (PF), Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK). The measurement was carried out one day after the sample was transferred from the BELSORP measurement cell to the vial. During measurement, single crystals were taken out from the container and immediately immersed in oil. Details of the analysis results are shown in Table 4. Note that these results are obtained after CO2 capture.

[0102]

Table 4

[0103] The single-crystal X-ray structure analysis results are shown in Figure 13. A linear electron density distribution, which was not observed after solvent removal, was found in the pore region. This distribution could be assigned to CO2, suggesting that CO2 is trapped in the pores. Since this measurement was performed in air, it is considered that this structure traps CO2 even when the sample is not present in a CO2 atmosphere.

[0104] <<FT-IR Measurement>> The FT-IR spectrum of the metal-organic framework [Cu4I4Lp] after CO2 capture is shown in Figure 14 ([I]). Furthermore, Figure 14 shows the FT-IR spectrum of the metal-organic structure [Cu4I4Lp] in the absence of acetonitrile and CO2 capture ([II]). This FT-IR spectrum was obtained by pulverizing a single crystal of the metal-organic structure [Cu4I4Lp] after vacuum heating, diluting it with KBr, and measuring it in room temperature air. Furthermore, the FT-IR spectrum before the removal of the solvent (acetonitrile) shown in Figure 6 is also shown in Figure 14 ([III]). [I]: After CO2 capture [II]: After vacuum heating [III]: Before removal of solvent (acetonitrile)

[0105] The wavenumber 2200 cm was present before the removal of the solvent (acetonitrile) ([III]). -1 From 2300cm -1 The peak [A] was observed to disappear after vacuum heating ([II]). This peak is thought to originate from the solvent acetonitrile, suggesting that the solvent in the pores was completely removed by vacuum heating. This finding is consistent with the results obtained from single-crystal X-ray structure analysis. [A]: C≡N vibration (acetonitrile) [B]: C=O(CO2) asymmetric vibration

[0106] Furthermore, after capturing CO2, 2300 cm³ -1 From 2400cm -1 A new peak [B] has appeared (see [I]). This is thought to originate from CO2, indicating that the structure is trapping CO2 and is also trapping CO2 in the air. Furthermore, when this single crystal was left in the air for a week, the CO2 peak was observed to remain, albeit with a decrease in height. From this, it can be inferred that the structure continues to maintain a state of CO2 trapping in the air.< / pxrd>

Claims

1. A carbon dioxide scavenger containing a metal-organic structure, The aforementioned metal-organic structure is capable of capturing carbon dioxide and desorbing carbon dioxide. Within the metal-organic structure, an isolated space is formed by the three-dimensional structure of the metal-organic structure. The aforementioned isolated space is a space capable of capturing carbon dioxide, and which under normal conditions does not have channels through which carbon dioxide can pass. Although the three-dimensional structure of the metal-organic structure changes during the process in which carbon dioxide is trapped in the isolated space and the process in which carbon dioxide is released from the isolated space, the three-dimensional structure of the metal-organic structure when carbon dioxide is trapped in the isolated space is the same as the three-dimensional structure of the metal-organic structure when carbon dioxide is not trapped in the isolated space. The aforementioned metal-organic structure contains a compound represented by the following formula (1) as a ligand. Carbon dioxide scavenging agent. 【Chemistry 1】 (In formula (1) above, X11 and X13 are N and X12, X14 and X15 are CR, or X12 and X14 are N and X11, X13 and X15 are CR, or X11 and X15 are N and X12, X13 and X14 are CR. X21 and X23 are N and X22, X24 and X25 are CR, or X22 and X24 are N and X21, X23 and X25 are CR, or X21 and X25 are N and X22, X23 and X24 are CR. X 31 and X 33 are N and X 32, X 34 and X 35 are CR, or X 32 and X 34 are N and X 31, X 33 and X 35 are CR, or X 31 and X 35 are N and X 32, X 33 and X 34 are CR. X 41 and X 43 are N and X 42, X 44 and X 45 are CR, or X 42 and X 44 are N and X 41, X 43 and X 45 are CR, or X 41 and X 45 are N and X 42, X 43 and X 44 are CR. Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom. R1 to R6 are each independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom.

2. The aforementioned metal-organic structure, N ２ In the specific surface area measurement using this method, the BET specific surface area is 1 m ２ The carbon dioxide scavenging agent according to claim 1, wherein the amount is less than or equal to / g.

3. The carbon dioxide scavenger according to claim 1 or 2, wherein the metal-organic structure forms an interpenetrating structure in which two frameworks interpenetrate each other.

4. The carbon dioxide scavenger according to claim 3, wherein in the metal-organic structure, the elements constituting the isolated space and the carbon dioxide trapped within the isolated space do not form a chemical bond.

5. The carbon dioxide scavenger according to claim 4, wherein the metal-organic structure contains at least one of the group II to group XIV elements as a constituent element.

6. The carbon dioxide scavenger according to claim 4, wherein the metal-organic structure contains a halogen element as a constituent element.

7. The carbon dioxide scavenger according to claim 1, wherein the compound represented by formula (1) is the compound represented by the following formula (1-1). 【Chemistry 2】 (In the above formula (1-1), Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom. R １ ~R ６ Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom.

8. The compositional formula of the aforementioned metal-organic structure is such that, if L is the ligand, Cu ４ I ４ A carbon dioxide scavenger according to claim 4, represented by L.

9. A metal-organic structure containing at least one element from Group II to Group XIV as a constituent element, and a compound represented by the following formula (1) as a ligand. 【Transformation 3】 (In formula (1) above, X １１ and X １３ are N, and X １２ , X １４ and X １５ is CR; or X １２ and X １４ are N, and X １１ , X １３ and X １５ is CR; or X １１ and X １５ are N, and X １２ , X １３ and X １４ is CR. X ２１ and X ２３ is N and X ２２ , X ２４ and X ２５ Is it CR, or X ２２ and X ２４ is N and X ２１ , X ２３ and X ２５ Is it CR, or X ２１ and X ２５ is N and X ２２ , X ２３ and X ２４ It is CR. X ３１ and X ３３ is N and X ３２ , X ３４ and X ３５ Is it CR, or X ３２ and X ３４ is N and X ３１ , X ３３ and X ３５ Is it CR, or X ３１ and X ３５ is N and X ３２ , X ３３ and X ３４ It is CR. X ４１ and X ４３ is N and X ４２ , X ４４ and X ４５ Is it CR, or X ４２ and X ４４ is N and X ４１ , X ４３ and X ４５ Is it CR, or X ４１ and X ４５ is N and X ４２ , X ４３ and X ４４ It is CR. Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom. R １ ~R ６ Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom.

10. The metal-organic structure according to claim 9, wherein the compound represented by formula (1) is the compound represented by the following formula (1-1). 【Chemistry 4】 (In the above formula (1-1), Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom. R １ ~R ６ Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom.

11. The metal-organic structure according to claim 9, comprising a halogen element as a constituent element.

12. If the ligand is L, then the composition formula is Cu ４ I ４ A metal-organic structure according to claim 9, represented by L.

13. The aforementioned constituent elements include copper, The metal-organic structure according to claim 9, wherein the ligand is coordinated to the copper by one of the two nitrogen atoms of the pyrimidine ring of the ligand.

14. The aforementioned constituent elements include copper and iodine. Cu in the metal-organic framework ４ I ４ The metal-organic structure according to claim 9, wherein the cubane exists in a cubane form.

15. The aforementioned constituent elements include copper and iodine. Cu in the metal-organic framework ４ I ４ It exists in the cubane form, If the ligand is L, then the composition formula is Cu ４ I ４ Represented by L, The metal-organic structure according to claim 9, wherein the ligand is coordinated to the copper by one of the two nitrogen atoms of the pyrimidine ring of the ligand.

16. A carbon dioxide scavenger containing a metal-organic structure according to any one of claims 9 to 15.

17. A compound represented by the following formula (1). 【Transformation 5】 (In formula (1) above, X １１ and X １３ are N and X １２ , X １４ and X １５ are CR, or X １２ and X １４ are N and X １１ , X １３ and X １５ are CR, or X １１ and X １５ are N and X １２ , X １３ and X １４ are CR. X ２１ and X ２３ are N, and X ２２ , X ２４ and X ２５ are CR; or X ２２ and X ２４ are N, and X ２１ , X ２３ and X ２５ are CR; or X ２１ and X ２５ are N, and X ２２ , X ２３ and X ２４ are CR. X ３１ and X ３３ is N and X ３２ , X ３４ and X ３５ Is it CR, or X ３２ and X ３４ is N and X ３１ , X ３３ and X ３５ Is it CR, or X ３１ and X ３５ is N and X ３２ , X ３３ and X ３４ It is CR. X ４１ and X ４３ is N and X ４２ , X ４４ and X ４５ Is it CR, or X ４２ and X ４４ is N and X ４１ , X ４３ and X ４５ Is it CR, or X ４１ and X ４５ is N and X ４２ , X ４３ and X ４４ It is CR. Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom. R １ ~R ６ Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom.

18. The compound according to claim 17, which is a compound represented by the following formula (1-1). 【Transformation 6】 (In the above formula (1-1), Each R is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom. R １ ~R ６ Each of these is independently a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom, an alkyloxy group which may be substituted with a halogen atom, or an aryl group which may be substituted with a halogen atom, an alkyl group which may be substituted with a halogen atom, or an alkyloxy group which may be substituted with a halogen atom.

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