JP5099614B2 - Novel metal carboxylate complex and gas storage agent comprising the same - Google Patents

Description

  The present invention relates to a novel carboxylic acid metal complex and a gas storage agent comprising the same.

  Patent Document 1 describes a carboxylic acid metal complex composed of benzoic acid, a metal, and an organic ligand capable of bidentate coordination with the metal, and that the complex is useful as a methane gas occlusion material. Are listed. Non-Patent Document 1 describes a single crystal in which an organometallic complex composed of benzoic acid, rhodium, and pyrazine is connected one-dimensionally, and the metal complex adsorbs carbon dioxide as a guest molecule. It is also described that the crystal structure changes upon desorption.

Japanese Unexamined Patent Publication No. 2000-309592 Satoshi Takamizawa et al., Angew. Chem. Int. Ed. 2003, 42, 4331-4334

  An object of the present invention is to provide a novel organometallic complex having a new chemical structure and physical properties different from those of the organometallic complexes described in the above-mentioned known documents and useful for the adsorption and desorption of various gases, and a gas storage agent comprising the same Is to provide.

  As a result of earnest research, the inventor of the present application has found that an organic carboxylic acid metal complex composed of a carboxylic acid, a divalent metal, and a pyrazine is unsubstituted by introducing a specific substituent on the pyrazine ring. The present inventors have found that a variety of organic carboxylic acid metal complexes and gas storage agents can be provided that can significantly change the crystal structure and physical properties as compared to the above case, and have different adsorption properties for various gases.

  That is, the present invention provides an organic carboxylic acid metal complex composed of a repeating unit represented by the general formula [I].

(However, M ¹ and M ² are divalent metals independently of each other, R ^1a , R ^1b , R ^1c and R ^1d are independently of each other an ^optionally substituted phenyl group (the substituent is carbon An alkyl group having 1 to 4 carbon atoms, a haloalkyl group having 1 to 4 carbon atoms, a hydroxyl group, an amino group, a cyano group, an alkylamino group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a halogen atom and substituted An optionally substituted phenyl group (the substituent is the same as the above substituent (excluding the substituted phenyl group)) , R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl having 1 to 4 carbon atoms. Group or an alkenyl group having 1 to 4 carbon atoms)

  Moreover, this invention provides the gas storage agent which consists of the organic carboxylic acid metal complex of the said invention. Furthermore, the present invention provides a gas adsorption permeable membrane comprising a single crystal of the carboxylic acid metal complex.

  According to the present invention, an organic carboxylic acid metal complex having a novel chemical structure and a gas storage agent using the same are provided. According to the present invention, a variety of organic carboxylic acid metal complexes having different crystal structures by bonding specific substituents to the pyrazine ring of the organic carboxylic acid metal complex, resulting in different adsorption and desorption characteristics for various gases. And a gas storage agent.

As described above, the organic carboxylic acid metal complex of the present invention is composed of a repeating unit having a structure represented by the above general formula [I]. In the general formula [I], coordinate bonds exist between M ¹ and O, between M ² and O, between M ¹ and M ² and between M ² and N. The repeating number of the repeating unit represented by the general formula [I] is not particularly limited, but is usually 10 to 10 ⁸ , preferably 10 ² to 10 ⁷ . As is clear from the general formula [I], among the four oxygen atoms bonded to M ¹ in the general formula [I], the upper right oxygen atom is the carbon atom bonded to R ^1b. The oxygen atom in the lower right is bonded to the carbon atom to which R ^1c is bonded. Similarly, of the four oxygen atoms bonded to M ² , the upper left oxygen atom is bonded to the carbon atom bonded to R ^1a , and the lower left oxygen atom is bonded to R ^1d . It is bonded to a carbon atom.

In the general formula [I], M ¹ and M ² are metal atoms that can be divalent independently of each other, and may be transition metals or typical metals. Preferable examples of M ¹ and M ² include manganese, iron, cobalt, nickel, copper, zinc, ruthenium, rhodium, chromium, molybdenum, palladium and tungsten. Among these, copper and rhodium are particularly preferable. M ¹ and M ² are preferably the same type of metal atom.

In the general formula [I], R ^1a , R ^1b , R ^1c and R ^1d (hereinafter, R ^1a , R ^1b , R ^1c and R ^1d may be collectively referred to as “R ¹ ”) are mutually Independently, it is an optionally substituted phenyl group , and an unsubstituted phenyl group is particularly preferable. When the phenyl group is substituted, the substituent is an alkyl group having 1 to 4 carbon atoms, a haloalkyl group having 1 to 4 carbon atoms, a hydroxyl group, an amino group, a cyano group, an alkylamino group having 1 to 4 carbon atoms, These are an alkoxyl group having 1 to 4 carbon atoms, a halogen atom and an optionally substituted phenyl group (the substituent is the same as described above (excluding the substituted phenyl group)) , and the number of substituents is 1 to 5. In the present specification, the “alkyl group” includes both a linear alkyl group and a branched alkyl group unless otherwise specified. The same applies to “alkenyl group” and “alkoxyl group”. R ^1a , R ^1b , R ^1c and R ^1d are preferably the same kind of the above-mentioned optionally substituted phenyl groups.

In the general formula ^{[I], R 2, R} 3, R 4 and R ⁵ are each independently hydrogen, represents an alkyl or alkenyl group having 1 to 4 carbon atoms having 1 to 4 carbon atoms, R ^2, Except when R ³ , R ⁴ and R ⁵ are simultaneously hydrogen atoms. Preferable examples of R ² , R ³ , R ⁴ and R ⁵ include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an allyl group and the like, and R ² , R ³ , R ⁴ and R Those in which 2 or 3 of ⁵ are hydrogen atoms are preferred. These substituents bonded to the pyrazine ring change the three-dimensional structure of the metal complex and the shape and size of the internal vacancies in the crystal, and thus the physical properties such as the gas adsorption characteristics.

The repeating units represented by the above general formula [I] are connected one-dimensionally, and they gather to constitute a molecular crystal. At this time, since the conjugated system of R ¹ approaches, a π-π bond is generated, and the crystal structure is stabilized. The molecular crystal is preferably a single crystal. Single crystals have the advantage that not only the amount of gas adsorption per unit volume can be increased, but also the physical properties can be made uniform, and complexes having predetermined physical properties can be produced with good reproducibility. Further, it can be used as a gas adsorption film as it is.

The organic carboxylic acid metal complex of the present invention includes a metal salt (two kinds of metal salts when M ¹ and M ² are different, the same shall apply hereinafter) and an organic carboxylic acid (R ¹ -COOH (R ¹ is as defined above, R ^1a , R ^1b , R ^1c, and R ^1d can be produced by slowly reacting a plurality of organic carboxylic acids (hereinafter the same)) and a substituted pyrazine in a solvent when they are a plurality of types of organic groups. The single crystal of the organic carboxylic acid metal complex of the present invention can be produced by this method. Alternatively, it can also be produced by reacting a metal salt of an organic carboxylic acid (R ¹ -COOH (R ¹ is as defined above)) with a substituted pyrazine in a solvent. As the solvent, methanol and acetonitrile are preferable. As the metal salt, acetate, formate, sulfate, nitrate and carbonate are preferable, and acetate is particularly preferable. The reaction temperature is not particularly limited and can be about 0 ° C. to 70 ° C., but good results can be obtained at room temperature. The reaction time is not particularly limited, but good results are usually obtained in about 3 hours to 1 week. The ratio of the metal salt to be reacted and the organic carboxylic acid is not particularly limited, but the molar ratio is usually about 1: 2 to 1: 8, and the ratio of the metal salt to the substituted pyrazine is usually 1: 0.5 in molar ratio. ˜1: 10 or so. In addition, the preferable example of a manufacturing method is described in detail in the following Example.

  The organic carboxylic acid metal complex of the present invention forms a molecular crystal, and the molecular crystal has pores (channel structure) or regularly arranged voids extending one-dimensionally inside the crystal. Since gas molecules can be adsorbed and desorbed in the crystal internal space, the organic carboxylic acid metal complex of the present invention can be used as a gas storage agent. The gas storage agent can be used for gas storage and separation / concentration. In the organic carboxylic acid metal complex of the present invention, by enclosing gas molecules in the channel structure, the crystal structure changes, and the shape and size of the channel structure change. For this reason, various gas molecules can be optimally included, and the occlusion amount of gas per unit volume is also large. In addition, since the organic carboxylic acid metal complex single crystal of the present invention is a porous body having a channel structure therein, it can be used as it is as a gas adsorption film. This gas adsorption membrane can be used as a filter for separating and concentrating gases.

  Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to the following examples.

Reference Example 1, Examples 1 to 5 Production and properties of copper complex Copper acetate (II) monohydrate, 80 mg (2.4x10 ^-4 mol) and benzoic acid 117.2 mg (8.4, Road 10 ^-4 mol) in 80 ml of methanol To give a blue solution. After filtration, pyrazine: 8.0 mg (Reference Example 1), 2-methylpyrazine: 0.3 ml (Example 1), 2,3-dimethylpyrazine: 0.3 ml (Example 2), 2-ethylpyrazine: 0.3 ml (implemented) Example 3), 2,3-diethylpyrazine: 0.3 ml (Example 4) or 2-propylpyrazine: 0.3 ml (Example 5) was added and allowed to react slowly at room temperature for 24 hours. A blue single crystal was formed. Pyrazine complex (Reference Example 1): 12.2 mg (58.6%), 2-methylpyrazine complex (Example 1): 11.7 mg (57.4%), 2,3-dimethylpyrazine complex (Example 2): 16.0 mg (74.2 %), 2-ethylpyrazine complex (Example 3) (19.2%), 2,3-diethylpyrazine complex (Example 4) (13.2%), 2-propylpyrazine complex (Example 5) (39.3%). Identification was performed by single crystal X-ray structural analysis and elemental analysis. The number of repeating units represented by the general formula [I] was about 10 ^{4 to} 5 × 10 ⁵ calculated from the size of the produced crystal (about 10 ⁷ per 1 cm of crystal).

  The results of elemental analysis and X-ray structure analysis are shown in Table 1 below.

  The physical property data of each obtained single crystal is shown in Table 2-1 and Table 2-2 below.

Reference Example 2, Examples 6 to 10 Production and properties of rhodium complex 80 mg (1.0 × 10 ⁻⁴ mol) of synthesized rhodium benzoate was dissolved in 80 ml of acetonitrile to obtain a red-purple solution. After filtration, pyrazine: 8.0 mg (Reference Example 2), 2-methylpyrazine: 0.3 ml (Example 6), 2,3-dimethylpyrazine: 0.3 ml (Example 7), 2-ethylpyrazine: 0.3 ml (implementation) Example 8), 2,3-diethylpyrazine: 0.3 ml (Example 9) or 2-propylpyrazine: 0.3 ml (Example 10) was added and allowed to react slowly at room temperature for 24 hours. Brown microcrystals were formed. Pyrazine complex (Reference Example 2): 12.9 mg (67.2%), 2-methylpyrazine complex (Example 6): 11.9 mg (60.7%), 2,3-dimethylpyrazine complex (Example 7): 16.3 mg (81.7 %), 2-ethylpyrazine complex (Example 8) (42.6%), 2,3-diethylpyrazine complex (Example 9) (85.5%), 2-propylpyrazine complex (Example 10) (14.6%). Identification was performed by single crystal X-ray structural analysis and elemental analysis. The number of repeating units represented by the general formula [I], calculated from the size of the produced crystal, was about 10 ^{4 to} 3 × 10 ⁵ .

  The results of elemental analysis and X-ray structure analysis are shown in Table 3 below.

  The physical property data of each obtained single crystal is shown together in the following Tables 4-1 and 4-2.

Example 11 Details of crystal structure Stereomicrographs of the single crystals produced in Examples 6 and 1, and the plane index and the positional relationship between the crystal plane and the channel direction revealed by X-ray single crystal structure analysis Figures are shown in a) and b) of FIG. Similarly, a stereomicrograph of the single crystal produced in Example 7 and Example 2, and a schematic diagram showing a plane index and a positional relationship between the crystal plane and the channel direction, which are clarified by X-ray single crystal structural analysis, respectively. This is shown in 2) a) and b). In these figures, thick arrows indicate the channel structure.

Example 12 Change in crystal structure before and after adsorption of carbon dioxide (part 1)
Carbon dioxide gas was adsorbed to the 2-methylpyrazine benzoate complex produced in Example 1 and Example 6, and changes in the crystal structure before and after that were examined by X-ray single crystal analysis. A crystal cross-sectional view of the benzoic acid 2-methylpyrazine complex before and after carbon dioxide adsorption is schematically shown in FIG. Similar results were obtained when the metal was copper (Example 1) or rhodium (Example 6). FIG. 4 schematically shows changes in the skeleton structure before and after the adsorption of carbon dioxide. For comparison, FIGS. 5 and 6 show changes in crystal cross-sectional views and skeleton structures of the benzoic acid pyrazine complexes of Reference Examples 1 and 2. FIG.

In the 2-methylpyrazine benzoate complex of Examples 1 and 6, the structure before adsorption is a zigzag one-dimensional chain accumulation structure bent due to steric hindrance of the methyl group of the 2-methylpyrazine ring. The molecular chain structure changes to a straight one-dimensional chain, and a one-dimensional channel is generated to include CO ₂ . The change in solid structure can be controlled by the introduction of substituents.

Table 5 shows changes in V _cell / Z and porosity before and after CO ₂ inclusion at 90K. V _cell / Z is the complex of Example 6 (2a): 813.1 → 893.3Å ³ (9.0% increase), the complex of Example 1 (2b): 812.9 → 900.1Å ³ (9.7% increase), and CO ₂ molecule Increasing the cell volume by inclusion. In addition, when comparing the void volume before and after inclusion, both 2a and 2b increase more than double, and the volume of the gas adsorbing space changes significantly due to the solid structure change.

(＊1) 包接CO₂を除いて算出

(* 1) Calculated excluding inclusion CO ₂

Example 13 Change in Crystal Structure before and after Adsorption of Carbon Dioxide (Part 2)
About the complex manufactured in Example 7, like Example 12, the state of the crystal | crystallization cross section before and behind making a carbon dioxide adsorb | suck was investigated by X-ray analysis. The results are schematically shown in FIG.

The CO ₂ arrangement state in the channel was different from the one-dimensional arrangement so far, and tetramer was generated. There is a characteristic that the structure of voids in the solid can be changed by introducing a substituent, and the guest molecule adsorption structure in the crystal can be controlled.

Example 14 Adsorption / desorption of carbon dioxide With respect to the complex (2a) produced in Example 6 or the complex (2b) produced in Example 1, the amount of carbon dioxide adsorbed was measured under isothermal or equal pressure. Isobaric adsorption measurement was performed at 1 atm, and isothermal adsorption measurement was performed at -70 ° C. The results are shown in FIGS. 8 (2a) and 9 (2b), respectively. In each figure, black circles indicate the adsorption amount in the adsorption process, and white circles indicate the adsorption amount in the desorption process.

  As shown in FIG. 8 and FIG. 9, the adsorption and desorption of each complex is reversible, and specific gas adsorption / desorption characteristics are exhibited by the crystal structure and crystal structure change. It was shown that it can be used.

Example 15 Adsorption / desorption of oxygen gas For the complex produced in Example 6, the complex produced in Example 1, the complex produced in Example 7, and the complex produced in Example 2, oxygen gas under isothermal conditions (77K) The adsorption amount of was measured. The results are shown in a), b), c) and d) of FIG. In each figure, black circles indicate the amount of adsorption in the adsorption process, and white circles indicate the amount of adsorption in the desorption process.

  As shown in FIG. 10, the adsorption and desorption of each complex is reversible, and the specific gas adsorption / desorption characteristics are exhibited by the crystal structure and the crystal structure change, so that oxygen gas can be separated and concentrated and used as a storage material. It was shown that.

Example 16 Adsorption / desorption of nitrogen gas For the complex produced in Example 6, the complex produced in Example 1, the complex produced in Example 7 and the complex produced in Example 2, nitrogen gas under isothermal conditions (77K) The adsorption amount of was measured. The results are shown in a), b), c) and d) of FIG. In each figure, black circles indicate the adsorption amount in the adsorption process, and white circles indicate the adsorption amount in the desorption process.

  As shown in FIG. 11, the adsorption and desorption of each complex is reversible, and the specific gas adsorption / desorption characteristics are exhibited by the crystal structure and the crystal structure change, so that nitrogen gas can be separated and concentrated and used as a storage material. It was shown that.

Example 16 Adsorption and Desorption of Nitric Oxide Gas For the complex produced in Example 6 and the complex produced in Example 1, the amount of nitrogen monoxide gas adsorbed under isothermal conditions (20 ° C.) was measured. The results are shown in a) and b) of FIG. In each figure, black circles indicate the adsorption amount in the adsorption process, and white circles indicate the adsorption amount in the desorption process.

  As shown in FIG. 12, the adsorption and desorption of each complex is reversible, and the specific gas adsorption / desorption characteristics are exhibited by the crystal structure and the crystal structure change. The separation and concentration of nitric oxide can be used as a storage material. It was shown to be possible.

Stereomicrographs of complex single crystals produced in Example 6 (a) and Example 1 (b) of the present invention, as well as the plane index and the positional relationship between the crystal plane and the channel direction revealed by X-ray single crystal structure analysis It is a schematic diagram which shows. Stereomicrographs of complex single crystals produced in Example 7 (a) and Example 2 (b) of the present invention, as well as plane indices and positional relations between crystal planes and channel directions revealed by X-ray single crystal structure analysis It is a schematic diagram which shows. It is a figure which shows typically the crystal | crystallization sectional drawing before and behind carbon dioxide adsorption of the benzoic acid 2-methylpyrazine complex single crystal manufactured in the Example of this invention. It is a figure which shows typically the change of the frame | skeleton structure before and behind carbon dioxide adsorption of the benzoic acid 2-methylpyrazine complex single crystal manufactured in the Example of this invention. It is a figure which shows typically the crystal | crystallization sectional drawing before and behind carbon dioxide adsorption of the benzoic acid pyrazine complex single crystal manufactured by the reference example of this invention. It is a figure which shows typically the change of the frame | skeleton structure before and behind carbon dioxide adsorption of the benzoic acid pyrazine complex single crystal manufactured by the reference example of this invention. It is a figure which shows typically the crystal | crystallization cross section before and behind making a carbon dioxide adsorb | suck about the complex manufactured in Example 7 of this invention. It is a figure which shows the result of having measured the adsorption amount of the carbon dioxide under isothermal or isobaric pressure about the complex manufactured in Example 6 of this invention. It is a figure which shows the result of having measured the adsorption amount of the carbon dioxide about the complex manufactured in Example 1 of this invention under isothermal or an equal pressure. The complex (a) produced in Example 6 of the present invention, the complex (b) produced in Example 1, the complex (c) produced in Example 7 and the complex (d) produced in Example 2 were kept isothermally. It is a figure which shows the result of having measured the adsorption amount of oxygen gas in (77K). The complex (a) produced in Example 6 of the present invention, the complex (b) produced in Example 1, the complex (c) produced in Example 7 and the complex (d) produced in Example 2 were kept isothermally. It is a figure which shows the result of having measured the adsorption amount of the nitrogen gas in (77K). It is a figure which shows the result of having measured the adsorption amount of the nitric oxide gas in isothermal (20 degreeC) about the complex (a) manufactured in Example 6 and the complex (b) manufactured in Example 1 of this invention.

Claims (7)

An organic metal carboxylate complex composed of a repeating unit represented by the general formula [I].

(However, M ¹ and M ² are divalent metals independently of each other, R ^1a , R ^1b , R ^1c and R ^1d are independently of each other an ^optionally substituted phenyl group (the substituent is carbon An alkyl group having 1 to 4 carbon atoms, a haloalkyl group having 1 to 4 carbon atoms, a hydroxyl group, an amino group, a cyano group, an alkylamino group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a halogen atom and substituted An optionally substituted phenyl group (substituents are the same as above (excluding substituted phenyl groups)) , R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or An alkenyl group having 1 to 4 carbon atoms, and a case where R ² , R ³ , R ⁴ and R ⁵ are hydrogen atoms at the same time). The M ¹ and M ² are each independently at least one selected from the group consisting of manganese, iron, cobalt, nickel, copper, zinc, ruthenium, rhodium, chromium, molybdenum, palladium and tungsten. Organic carboxylic acid metal complex. M ¹ and M ² are the same type of metal, and R ^1a , R ^1b , R ^1c and R ^1d are the same type of ^optionally substituted phenyl group (the substituent is an alkyl group having 1 to 4 carbon atoms) , A haloalkyl group having 1 to 4 carbon atoms, a hydroxyl group, an amino group, a cyano group, an alkylamino group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a halogen atom, and an optionally substituted phenyl group ( The organic carboxylic acid metal complex according to claim 1 or 2, wherein the substituent is the same as described above (excluding the substituted phenyl group) . R ^1a , R ^1b , R ^1c and R ^1d are phenyl groups, R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, M ¹ and M The organic carboxylic acid metal complex according to claim 3 , wherein ² is copper or rhodium. The organic carboxylic acid metal complex according to any one of claims 1 to 4 , which is in the form of a single crystal (excluding a single crystal having a long side length of 0.8 mm or more) . A gas storage agent comprising the organic carboxylic acid metal complex according to any one of claims 1 to 5 . A gas adsorption permeable membrane comprising the organic carboxylic acid metal complex single crystal according to claim 5 .

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