Metal-organic structures with a dibenzothiophene skeleton and hydroxamic acid ions as organic ligands

Abstract

To provide a novel metal-organic framework with a gas storage function, and a gas storage agent and a gas storage method using the same.SOLUTION: The invention provides a metal-organic framework in which a polyvalent metal ion is bonded to a dianion of a compound represented by formula (1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a metal-organic structure having a hydroxamic acid ion having a dibenzothiophene skeleton as an organic ligand, a gas storage agent containing the metal-organic structure, and a gas storage method comprising the step of contacting the metal-organic structure with a gas. [Background technology]

[0002] Metal-organic structures (hereinafter sometimes referred to as "MOFs") are solid materials that have a polymeric structure with internal spaces (i.e., pores) formed by combining metal ions with cross-linking organic ligands that connect them. They have attracted considerable interest over the past decade or so as porous materials with functions such as gas storage and separation. For example, a material with a surface area of ​​4000 m² obtained by heating zirconium chloride and terphenyldicarboxylic acid in dimethylformamide... 2 It is known that MOFs at a concentration of / g can store gases such as hydrogen, methane, and acetylene (see Patent Document 1). Furthermore, it is known that MOFs can be obtained as dark brown crystals by heating a dicarboxylic acid represented by the following formula and Fe2CoO(CH3COO)6 or Fe3O(CH3COO)6 in the presence of acetic acid in N-methylpyrrolidone at 150°C for 24 hours, and that these MOFs can store gases such as hydrogen, methane, carbon dioxide, and nitrogen (see Patent Document 2).

[0003] [ka]

[0004] Furthermore, Patent Document 2 discloses a metal-organic structure in which a dicarboxylic acid ion obtained from a dicarboxylic acid represented by the following formula is bonded to Fe.

[0005] [ka]

[0006] In the course of such development, it is known that the structure of metal-organic frameworks changes significantly depending on the metal compounds, organic ligands, and reaction conditions used, and there is a further need to develop new metal-organic frameworks having a gas storage function.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] <a An object of the present invention is to provide a novel metal-organic framework having a gas storage function, a gas storage agent using the same, and a gas storage method. <0<a000075>

Means for Solving the Problems

[0009] As a result of intensive studies to solve the above problems, the present inventors have found a novel metal-organic framework obtained by using a specific dihydroxamic acid having a dibenzothiophene skeleton or a dibenzofuran skeleton as an organic ligand. Further, it has been found that these novel metal-organic frameworks have a high hydrogen storage capacity, leading to the completion of the present invention.

[0010] That is, the present invention is specified by the following matters. [1] A metal-organic framework formed by bonding a dianion of a compound represented by formula (1) and a polyvalent metal ion.

Chemical Formula

Chemical formula

Advantages of the Invention

[0011] The metal-organic structure of the present invention is novel and can store gases such as hydrogen, carbon dioxide, and nitrogen.

Modes for Carrying Out the Invention

[0012] The metal-organic framework of the present invention is a metal-organic framework formed by the binding of a dianion of a compound represented by formula (1) and a polyvalent metal ion.

[0013]

Chemical formula

[0014] In formula (1), X is a sulfur atom, SO2, or an oxygen atom. R 1 is a hydroxy group, a C1-6 alkyl group, a C1-6 alkoxy group, or a halogeno group. n1 and n2 represent the number of R 1 , and are any integer from 0 to 3. When R 1 is 2 or more, each R 1 may be the same as or different from each other. R 3 is each independently a hydrogen atom or a C1-6 alkyl group. L is any divalent group represented by the following formula (2). m1 and m2 represent the number of L, and are 0 or 1. When L is 2 or more, each L may be the same as or different from each other.

[0015]

Chemical formula

[0016] R 1 and R 3 Examples of the C1-6 alkyl group of may be linear or branched, and include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an i-propyl group, an i-butyl group, an s-butyl group, a t-butyl group, an i-pentyl group, a neopentyl group, a 2-methyl-n-butyl group, an i-hexyl group, etc. R 1 Examples of the C1-6 alkoxy group of include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an s-butoxy group, an i-butoxy group, a t-butoxy group, etc. R 1Examples of halogen groups include fluoro groups, chloro groups, bromo groups, and iod groups.

[0017] In formula (2), R 2 n3 is R 2 This indicates the number, which is an integer between 0 and 4. 2 When R is 2 or greater, each R 2 They may be the same or different from each other. 2 The C1-6 alkyl group may be linear or branched, and examples include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, i-propyl group, i-butyl group, s-butyl group, t-butyl group, i-pentyl group, neopentyl group, 2-methyl-n-butyl group, i-hexyl group, etc. 2 Examples of C1-6 alkoxy groups include methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, s-butoxy group, i-butoxy group, t-butoxy group, etc. 2 Examples of halogen groups include fluoro groups, chloro groups, bromo groups, and iod groups. * and ** indicate bond positions, and ** is CON(R 3 This indicates the bond position with OH. Terms such as "C1~6" indicate that the parent group has 1 to 6 carbon atoms, etc. Specifically, examples of compounds represented by formula (1) include those shown in the following formulas. While the following formulas illustrate the case where X is S, similar structures can be illustrated when X is O or SO2.

[0018] [ka] TIFF0007874259000008.tif179170TIFF0007874259000009.tif161170

[0019] The polyvalent metal ions in the metal-organic structure of the present invention are not particularly limited as long as they are ions of metals with a valency of 2 or higher, but at least one metal ion selected from the group consisting of metals from Group 2 to Group 13 of the periodic table is preferred, and at least one metal ion selected from Zn, Al, Cu, Zr, Ni, Co, Cr, Fe, Sc, Mo, Mn, Ti, and Mg is more preferred. In the metal-organic structure of the present invention, the polyvalent metal ions that bond to the dianion of the compound represented by formula (1) may be one or two or more.

[0020] Various metal compounds can be used as polyvalent metal ion sources. Specifically, zinc nitrate (Zn(NO3)2·xH2O), titanium nitrate (Ti(NO3)4·xH2O), cobalt nitrate (Co(NO3)2·xH2O), iron(III) nitrate (Fe(NO3)3·xH2O), iron(II) nitrate (Fe(NO3)2·xH2O), nickel(II) nitrate (Ni(NO3)2·xH2O), copper(II) nitrate (Cu(NO3)2·xH2O), aluminum(III) nitrate (Al(NO3)3·xH2O), magnesium(II) nitrate (Mg(NO3)2·xH2O); zinc chloride (ZnCl2·xH2O), salt Titanium chloride (TiCl4·xH2O), zirconium chloride (ZrCl4·xH2O), cobalt chloride (CoCl2·xH2O), iron(III) chloride (FeCl3·xH2O), iron(II) chloride (FeCl2·xH2O), chromium(III) chloride (CrCl3·xH2O), scandium(III) chloride (ScCl3·xH2O), manganese(II) chloride (MnCl2·xH2O); zinc acetate (Zn(CH3COO)2·xH2O), titanium acetate (Ti(CH3COO)4·xH2O), zirconium acetate (Zr(CH3COO)4·xH2O) O), cobalt acetate (Co(CH3COO)2·xH2O), iron(III) acetate (Fe(CH3COO)3·xH2O), iron(II) acetate (Fe(CH3COO)2·xH2O); zinc sulfate (ZnSO4·xH2O), titanium sulfate (Ti(SO4)2·xH2O), zirconium sulfate (Zr(SO4)2·xH2O), cobalt sulfate (CoSO4·xH2O), iron(III) sulfate (Fe2(SO4)3·xH2O), iron(II) sulfate (FeSO4·xH2O), magnesium(II) sulfate (MgSO4·xH2O); zinc hydroxide (Zn( (OH)2·xH2O), Titanium hydroxide (Ti(OH)4·xH2O), Zirconium hydroxide (Zr(OH)4·xH2O), Cobalt hydroxide (Co(OH)2·xH2O), Iron(III) hydroxide (Fe(OH)3·xH2O), Iron(II) hydroxide (Fe(OH)2·xH2O); Zinc bromide (ZnBr2·xH2O), Titanium bromide (TiBr4·xH2O), Zirconium bromide (ZrBr4·xH2O), Cobalt bromide (CoBr2·xH2O), Iron(III) bromide (FeBr3·xH2O), Iron(II) bromide (FeBr2·xH2O);Examples include zinc carbonate (ZnCO3·xH2O), cobalt carbonate (CoCO3·xH2O), iron(III) carbonate (Fe2(CO3)3·xH2O); zirconium chloride oxide (ZrOCl2·xH2O); and molybdenum(II) acetate dimer ((Mo(CH3COO)2)2). Note that x is a number from 0 to 12. These can be used individually or in mixtures of two or more.

[0021] The metal-organic structure of the present invention may contain organic ligands other than the compound represented by formula (1) as auxiliary ligands. By incorporating auxiliary ligands into metal-organic structures, higher-order structures can be introduced into these structures. Examples of such auxiliary ligands include terephthalic acid, phthalic acid, isophthalic acid, 5-cyanoisophthalic acid, 1,3,5-trimesic acid, 1,3,5-tris(4-carboxyphenyl)benzene, 4,4'-dicarboxybiphenyl, 3,5-dicarboxypyridine, 2,3-dicarboxypyrazine, 1,3,5-tris(4-carboxyphenyl)benzene, 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, 9,10-anthracenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, [1,1':4',1”]terphenyl-3,3”,5,5”-tetracarboxylic acid, biphenyl-3,3”,5,5”-tetracarboxylic acid, 3,3',5,5'-tetracarboxydiphenylmethane, and 1,3,5-tris(4'-carboxy[1,1'-bi Examples include phenyl]-4-yl)benzene, 1,3,5-tris(4-carboxyphenyl)triazine, 1,2-bis(4-carboxy-3-nitrophenyl)ethene, 1,2-bis(4-carboxy-3-aminophenyl)ethene, trans,trans-muconic acid, fumaric acid, picolinic acid, nicotinic acid, isonicotinic acid, 4-(pyridine-4-yl)benzoic acid, benzimidazole, imidazole, 1,4-diazabicyclo[2.2.2]octane (DABCO), pyrazine, 4,4'-dipyridyl, 1,2-di(4-pyridyl)ethylene, 1,2-di(4-pyridyl)ethane, 2,7-diazapyrene, 4,4'-azobispyridine, 1,5-naphthyridine, phenazine, and 2-bis(3-(4-pyridyl)-2,4-pentanedionato)copper. The molar ratio of the compound represented by formula (1) and the auxiliary ligand is not particularly limited.

[0022] The present invention is not particularly limited as a method for producing the metal-organic structure, and any of the following methods can be used: solution methods such as solvent diffusion, solvent stirring, and hydrothermal methods; microwave methods in which microwaves are irradiated onto the reaction solution to uniformly heat the entire system in a short time; ultrasonic methods in which ultrasonic waves are irradiated onto the reaction vessel to repeatedly cause pressure changes in the reaction vessel, and this pressure change causes a phenomenon called cavitation in which the solvent forms bubbles and collapses, at which time a high-energy field of about 5000K and 10000 bar is locally formed, which serves as the reaction field for the formation of each crystal; solid-phase synthesis methods in which a metal ion source and an organic ligand are mixed without using a solvent; and LAG (liquid-assisted grinding) methods in which water in the amount of crystal water is added and the metal ion source and the organic ligand are mixed.

[0023] For example, the process includes the steps of preparing a first solution containing a metal compound that serves as a source of metal ions and a solvent, a second solution containing a compound represented by formula (1) or its dianion and a solvent, and, if necessary, a third solution containing an auxiliary ligand and a solvent, and the steps of mixing the first solution, the second solution and the third solution to prepare a reaction solution, and heating this reaction solution to obtain a metal-organic structure. The first to third solutions do not need to be prepared separately; for example, the metal compound, the compound represented by formula (1) or its dianion, the auxiliary ligand and the solvent may be mixed at once to prepare a single solution.

[0024] The molar ratio of the above-mentioned metal compound to the compound represented by formula (1) or its dianion can be arbitrarily selected depending on the pore size and surface properties of the resulting metal-organic structure. However, it is preferable to use 0.8 moles or more of the metal compound per mole of the compound represented by formula (1) or its dianion, and more preferably 1 mole or more.

[0025] The concentration of the above metal ions in the reaction solution is preferably in the range of 20 to 200 mmol / L. The concentration of the compound represented by formula (1) or its dianion in the reaction solution is preferably in the range of 10 to 100 mmol / L. The concentration of the auxiliary ligand in the reaction solution is preferably 10 to 100 mmol / L.

[0026] The solvent used is not particularly limited, but one or more solvents selected from the group consisting of N,N-dimethylformamide (hereinafter sometimes referred to as "DMF"), N,N-diethylformamide (hereinafter sometimes referred to as "DEF"), N,N-dimethylacetamide (hereinafter sometimes referred to as "DMA"), N-methyl-2-pyrrolidone (hereinafter sometimes referred to as "NMP"), dimethyl sulfoxide (hereinafter sometimes referred to as "DMSO"), and water can be used in mixtures. In addition, alcohols such as methyl alcohol and ethyl alcohol may be mixed with these solvents.

[0027] The heating temperature of the reaction solution is not particularly limited, but examples include ranges of room temperature to 140°C, 70 to 140°C, and 80 to 130°C.

[0028] The gas storage agent of the present invention comprises the metal-organic structure of the present invention. The gas storage agent of the present invention may consist only of the metal-organic structure of the present invention, or it may contain other components to the extent that it does not hinder its use as a gas storage agent. The shape of the gas storage agent of the present invention is not particularly limited, and examples include powder, granules, pellets, etc. The metal-organic structure of the present invention can store gases such as hydrogen, methane, acetylene, carbon dioxide, nitrogen, etc., by adsorbing or storing the said gases. The method of storing gas using the metal-organic structure of the present invention is not particularly limited, but a method of bringing the metal-organic structure of the present invention into contact with the gas is preferred, and the method of contact is not particularly limited. For example, examples include filling a tank with the metal-organic structure of the present invention to make a gas storage tank and introducing the gas into the tank, supporting the metal-organic structure of the present invention on the surface constituting the inner wall of a tank to make a gas storage tank and introducing the gas into the tank, and molding a tank from a material containing the metal-organic structure of the present invention to make a gas storage tank and introducing the gas into the tank. [Examples]

[0029] The present invention will be described in detail below with reference to examples of the present invention, but the technical scope of the present invention is not limited to these examples. Organic ligands 1 to 4 shown in Table 1 below were used as compounds represented by formula (1) that constitute the metal-organic structure of the present invention.

[0030] [Table 1]

[0031] When auxiliary ligands were included, the auxiliary ligands used were those shown in Table 2, Auxiliary Ligands 1 to 6.

[0032] [Table 2]

[0033] [Production Example 1] Synthesis of Organic Ligand 1 Dibenzothiophene-2,8-dicarboxylic acid (2.00 mmol) was dissolved in 40 mL of DMF, and oxalyl chloride (6.00 mmol) was slowly added at 0°C. The mixture was then heated to room temperature and stirred for 2.5 hours. To this, a suspension prepared by adding N-methylmorpholine (30.0 mmol) to hydroxylamine hydrochloride (20.0 mmol) in 20 mL of DMF solution and stirring at 0°C for 30 minutes was slowly added. The mixture was then heated and stirred overnight. The solvent in the resulting reaction solution was removed by reduced pressure distillation, and the mixture was washed with water and methanol to obtain 1.56 mmol of dibenzothiophene-2,8-dihydroxamic acid (organic ligand 1) as a colorless solid.

[0034] [Production Example 2] Synthesis of Organic Ligand 2 The procedure was the same as in Production Example 1, except that dibenzothiophene-3,7-dicarboxylic acid was used instead of dibenzothiophene-2,8-dicarboxylic acid, and organic ligand 2 was obtained as a colorless solid.

[0035] [Production Example 3] Synthesis of Organic Ligand 3 The procedure was carried out in the same manner as in Production Example 1, except that dibenzothiophene-3,7-dicarboxylic acid-5,5-dioxide was used instead of dibenzothiophene-2,8-dicarboxylic acid, and organic ligand 3 was obtained as a colorless solid.

[0036] [Production Example 4] Synthesis of Organic Ligand 4 The procedure was carried out in the same manner as in Production Example 1, except that dibenzothiophene-4,6-dicarboxylic acid was used instead of dibenzothiophene-2,8-dicarboxylic acid, and organic ligand 4 was obtained as a colorless solid.

[0037] The 1H-NMR data of the obtained organic ligands are shown below. organic ligand 1 1H-NMR (400 MHz, DMSO-d6) δ: 7.93 (d, J=8.4Hz, 2H), 8.15 (d, J=8.4Hz, 2H), 8.83 (s, 2H), 9.16(s, 2H), 11.4(s, 2H). organic ligand 2 1H-NMR (400 MHz, DMSO-d6) δ: 7.89 (d, J=8.4Hz, 2H), 8.43 (s, 2H), 8.49 (d, J=8.4Hz, 2H), 9.16(2H, s), 11.4(s, 2H). organic ligand 3 1H-NMR (400 MHz, DMSO-d6) δ:8.19 (d, J=8.0Hz, 2H), 8.28 (s, 2H), 8.35 (d, J=8.0Hz, 2H), 9.34(s, 2H), 11.6(s, 2H). organic ligand 4 1H-NMR (400 MHz, DMSO-d6) δ: 7.58 (t, J=8.0Hz, 2H), 7.91 (d, J=8.0Hz, 2H), 8.56 (d, J=8.0Hz, 2H), 9.24(s, 2H), 11.5(s,2H).

[0038] [Example 1-1] Organic ligand 1 (0.15 mmol) and zinc nitrate hexahydrate (0.15 mmol) were mixed with 3 mL of DMF and heated in an oven (reaction conditions: temperature 120°C, heating time 24 hours). The solution was allowed to return to room temperature, and the supernatant was removed. After washing with 10 mL of DMF, the solvent was removed and replaced with chloroform. 10 mL of chloroform was added, and the solution was immersed overnight. After removing the chloroform, the solution was vacuum-dried at 150°C for 5 hours to obtain metal-organic structure 1-1 as a colorless solid (properties). [Examples 1-2] to [Examples 1-10] Except for using the metal compounds shown in Table 3 and carrying out the reaction under the reaction conditions shown in Table 3, the same procedure as in Example 1-1 was followed to obtain metal-organic structures 1-2 to 1-10. The results are shown in Table 3.

[0039] [Table 3]

[0040] [Example 2-1] Organic ligand 1 (0.15 mmol) was dissolved in 3 mL of DMF, and auxiliary ligand 5 (0.15 mmol) and zinc nitrate hexahydrate (0.15 mmol) were added. The mixture was then heated in an oven (reaction conditions: temperature 90°C, heating time 48 hours). The solution was allowed to return to room temperature, and the supernatant was removed. After washing with 10 mL of DMF, the solvent was removed and replaced with chloroform. 10 mL of chloroform was added, and the solution was immersed overnight. After removing the chloroform, the solution was vacuum-dried at 150°C for 5 hours to obtain metal-organic structure 2-1 as a colorless solid (properties). [Examples 2-2] to [Examples 2-13] Except for using the metal compounds and auxiliary ligands shown in Table 4 below and carrying out the reaction under the reaction conditions shown in Table 4, the same procedure as in Example 2-1 was followed to obtain metal-organic structures 2-2 to 2-13. The results are shown in Table 4.

[0041] [Table 4]

[0042] [Example 3-1] Organic ligand 2 (0.1 mmol) and zinc nitrate hexahydrate (0.1 mmol) were mixed with 2 mL of DMF and heated in an oven (reaction conditions: temperature 120°C, heating time 48 hours). The solution was allowed to return to room temperature, and the supernatant was removed. After washing with 10 mL of DMF, the solvent was removed and replaced with chloroform. 10 mL of chloroform was added, and the solution was immersed overnight. After removing the chloroform, the solution was vacuum-dried at 150°C for 5 hours to obtain metal-organic structure 3-1 as a colorless solid (properties). [Example 3-2] to [Example 3-17] Except for using the metal compounds shown in Table 5 and carrying out the reaction under the reaction conditions shown in Table 5, the same procedure as in Example 3-1 was followed to obtain metal-organic structures 3-2 to 3-17. The results are shown in Table 5.

[0043] [Table 5]

[0044] [Example 4-1] Organic ligand 2 (0.1 mmol) was dissolved in 4 mL of DMF, and auxiliary ligand 5 (0.1 mmol) and zinc nitrate hexahydrate (0.1 mmol) were added. The mixture was then heated in an oven (reaction conditions: temperature 90°C, heating time 48 hours). The solution was allowed to return to room temperature, and the supernatant was removed. After washing with 10 mL of DMF, the solvent was removed and replaced with chloroform. 10 mL of chloroform was added, and the solution was immersed overnight. After removing the chloroform, the solution was vacuum-dried at 150°C for 5 hours to obtain metal-organic structure 4-1 as a colorless solid (properties). [Examples 4-2] to [Examples 4-44] Metal-organic structures 4-2 to 4-44 were obtained by following the same procedure as in Example 4-1, except that the metal compounds and auxiliary ligands shown in Table 6 were used and the reaction conditions shown in Table 6 were followed. The results are shown in Table 6. In Examples 4-10 and 4-11, the auxiliary ligands were added in the equivalent amounts indicated in the table.

[0045] [Table 6] TIFF0007874259000016.tif185170

[0046] [Example 5-1] Organic ligand 3 (0.1 mmol) and zinc nitrate hexahydrate (0.1 mmol) were mixed with 2 mL of DMF and heated in an oven (reaction conditions: temperature 120°C, heating time 48 hours). The solution was allowed to return to room temperature, and the supernatant was removed. After washing with 10 mL of DMF, the solvent was removed and replaced with chloroform. 10 mL of chloroform was added, and the solution was immersed overnight. After removing the chloroform, the solution was vacuum-dried at 150°C for 5 hours to obtain metal-organic structure 5-1 as a yellow solid (properties). [Examples 5-2] to [Examples 5-7] Except for using the metal compounds shown in Table 7 and carrying out the reaction under the reaction conditions shown in Table 7, the same procedure as in Example 5-1 was followed to obtain metal-organic structures 5-2 to 5-7. The results are shown in Table 7.

[0047] [Table 7]

[0048] [Example 6-1] Organic ligand 3 (0.1 mmol) was dissolved in 2 mL of DMF, and auxiliary ligand 5 (0.1 mmol) and zinc nitrate hexahydrate (0.1 mmol) were added. The mixture was then heated in an oven (reaction conditions: temperature 90°C, heating time 48 hours). The solution was allowed to return to room temperature, and the supernatant was removed. After washing with 10 mL of DMF, the solvent was removed and replaced with chloroform. 10 mL of chloroform was added, and the solution was immersed overnight. After removing the chloroform, the solution was vacuum-dried at 150°C for 5 hours to obtain metal-organic structure 6-1 as a colorless solid (properties). [Example 6-2]~[Example 6-25] Metal-organic structures 6-2 to 6-25 were obtained by following the same procedure as in Example 6-1, except that the metal compounds and auxiliary ligands shown in Table 8 were used and the reaction conditions shown in Table 8 were followed. The results are shown in Table 8. In Examples 6-2, 6-3, 6-7, and 6-8, the auxiliary ligands were added in the equivalent amounts indicated in the table.

[0049] [Table 8]

[0050] [Example 7-1] Organic ligand 4 (0.1 mmol) and zinc nitrate hexahydrate (0.1 mmol) were mixed with 2 mL of DMF and heated in an oven (reaction conditions: temperature 120°C, heating time 24 hours). The solution was allowed to return to room temperature, and the supernatant was removed. After washing with 10 mL of DMF, the solvent was removed and replaced with chloroform. 10 mL of chloroform was added, and the solution was immersed overnight. After removing the chloroform, the solution was vacuum-dried at 150°C for 5 hours to obtain metal-organic structure 7-1 as a colorless solid (properties). [Examples 7-2] to [Examples 7-8] Except for using the metal compounds shown in Table 9 and carrying out the reaction under the reaction conditions shown in Table 9, the same procedure as in Example 7-1 was followed to obtain metal-organic structures 7-2 to 7-8. The results are shown in Table 9.

[0051] [Table 9]

[0052] [Example 8-1] Organic ligand 4 (0.1 mmol) was dissolved in 3 mL of DMF, and auxiliary ligand 5 (0.1 mmol) and zinc nitrate hexahydrate (0.1 mmol) were added. The mixture was then heated in an oven (reaction conditions: temperature 90°C, heating time 48 hours). The solution was allowed to return to room temperature, and the supernatant was removed. After washing with 10 mL of DMF, the solvent was removed and replaced with chloroform. 10 mL of chloroform was added, and the solution was immersed overnight. After removing the chloroform, the solution was vacuum-dried at 150°C for 5 hours to obtain metal-organic structure 8-1 as a colorless solid (properties). [Example 8-2]~[Example 8-12] Metal-organic structures 8-2 to 8-12 were obtained by following the same procedure as in Example 8-1, except that the metal compounds and auxiliary ligands shown in Table 10 were used and the reaction was carried out under the reaction conditions shown in Table 10. The results are shown in Table 10.

[0053] [Table 10]

[0054] [Example 9] (BET specific surface area measurement and hydrogen storage capacity measurement) For some of the obtained metal-organic structures, the BET specific surface area and hydrogen storage capacity at 77K-atmospheric pressure were measured. The BET specific surface area and hydrogen storage capacity at 77K-atmospheric pressure were measured using the Tristar-II gas adsorption analyzer (Micromeritics). The BET specific surface area was calculated using the following method: Approximately 50 mg of a metal-organic structure was placed inside a glass cell. The inside of the glass cell was reduced to a vacuum at a temperature of 135°C and dried for 6 hours. The glass cell was mounted on a gas adsorption amount measuring device and immersed in a constant temperature bath containing liquid nitrogen. The pressure of the nitrogen contained in the glass cell was gradually increased. When the pressure of the nitrogen introduced into the glass cell reached 1.0 × 10⁻⁶ 5 Measurements were continued until the reading reached Pa. The amount of hydrogen stored at 77K atmospheric pressure was calculated using the following method. After measuring nitrogen, the gas type was changed to hydrogen and measurements were taken. The pressure of the hydrogen contained in the glass cell was gradually increased. The pressure of the hydrogen introduced into the glass cell was 1.0 × 10⁻⁶. 5 Measurements were continued until the reading reached Pa. The measured BET specific surface area results are shown in Table 11. Additionally, the measured hydrogen storage capacity at 77K-atmospheric pressure is also shown in Table 11.

[0055] [Table 11] [Industrial applicability]

[0056] The metal-organic structure of the present invention can store gases such as hydrogen at a practical level. Therefore, it can be suitably used in energy fields that utilize hydrogen, such as fuel cells.

Claims

1. A metal-organic structure formed by bonding a dianion of a compound represented by formula (1) with at least one polyvalent metal ion selected from Zn, Al, Cu, Zr, Ni, Co, Cr, Fe, Mn, Ti, and Mg. 【Chemistry 1】 （１） (In formula (1), X is a sulfur atom or SO2. R3 is independently either a hydrogen atom or a C1-6 alkyl group.

2. The metal-organic structure according to claim 1, further comprising an auxiliary ligand as a constituent component.

3. A hydrogen gas storage agent comprising the metal-organic structure according to claim 1 or 2.

4. A method for storing hydrogen gas, comprising the step of contacting a metal-organic structure according to claim 1 or 2 with hydrogen gas.

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