Metal organic framework and method for producing the same

Abstract

To provide means for producing a MOF having an RHO-type topology with high gas adsorption performance in high yields.SOLUTION: One aspect of the present invention relates to a metal organic framework containing metal ions as zinc cations and ligands as 2-ethylimidazole (2-EtIm) or monocarboxylic acid anions. The metal organic framework has an RHO-type topology in which the 2-EtIm anions are partially substituted with the monocarboxylic acid anions. Another aspect of the present invention relates to a method for producing the metal organic framework having the above-described features.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a metal-organic framework and a method for producing the same.

Background Art

[0002] A metal-organic framework (hereinafter also referred to as "MOF") is a crystalline porous material composed of a metal and an organic ligand. By combining the metals and organic ligands used, properties such as the pore diameter and surface shape of the MOF can be designed at the molecular level. MOFs are expected to be applied to, for example, gas storage materials, heterogeneous catalysts, and conductive materials.

[0003] For example, Non-Patent Document 1 describes a method for synthesizing a Zn(2-EtIm) MOF having a RHO-type topology composed of a metal ion which is a zinc cation and a ligand which is an anion of 2-ethylimidazole (2-EtIm) by a mechanochemical reaction. 2

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, a method for producing a Zn(2-EtIm) MOF having a RHO-type topology by a mechanochemical reaction is known. However, in the case of the conventional method, there is a problem that the yield is low due to the low solubility of the zinc compound as a raw material in an organic solvent. In addition, the MOF produced by the conventional method has room for improvement in gas adsorption properties. 2

[0006] Therefore, an object of the present invention is to provide a means for producing an MOF having an RHO-type topology with high gas adsorption properties in a high yield. **Means for Solving the Problems**

[0007] The present inventors have variously studied means for solving the above problems. The present inventors have found that in the production of MOF by a mechanochemical reaction, by adding a monocarboxylic acid to a zinc compound and 2-ethylimidazole as raw materials, an MOF having an RHO-type topology with a structure in which a part of 2-ethylimidazole is substituted with a monocarboxylic acid can be obtained in a high yield. Based on the above findings, the present inventors have completed the present invention.

[0008] That is, the present invention includes the following aspects and embodiments. **(Embodiment 1)** A metal-organic framework having an RHO-type topology, which consists of a metal ion that is a cation of zinc and a ligand that is an anion of 2-ethylimidazole (2-EtIm) or a monocarboxylic acid, and in which a part of the 2-EtIm anion is substituted by a monocarboxylic acid anion. **(Embodiment 2)** The metal-organic framework according to Embodiment 1, wherein the monocarboxylic acid is benzoic acid or acetic acid. **(Embodiment 3)** The metal-organic framework according to Embodiment 1 or 2, wherein the abundance ratio of the anion of the monocarboxylic acid in the ligand is in the range of 1 to 20 mol% with respect to the total number of moles of the ligand. **(Embodiment 4)** A mechanochemical reaction step of subjecting a zinc compound, 2-ethylimidazole (2-EtIm), and a monocarboxylic acid to a mechanochemical reaction in the presence of a solvent. A method for producing the metal-organic framework according to any one of Embodiments 1 to 3, including this step. **(Embodiment 5)** The method according to Embodiment 4, wherein the mechanochemical reaction includes mixing raw materials using a ball mill. **Advantages of the Invention**

[0009] The present invention makes it possible to provide a means for producing an MOF having an RHO-type topology with high gas adsorption properties in a high yield.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail.

[0012] <1: Metal-Organic Framework> Another aspect of the present invention relates to a metal-organic framework (MOF). The MOF of this aspect consists of a metal ion that is a cation of zinc (Zn) and a ligand that is an anion of 2-ethylimidazole (2-EtIm) or a monocarboxylic acid, and has a RHO type topology in which a part of the 2-EtIm anion is substituted by a monocarboxylic acid anion.

[0013] The MOF of Zn(2-EtIm) consisting of Zn and 2-EtIm 2 can take various topologies. Among these, Zn(2-EtIm) having a RHO type topology 2The MOF is known to have a large pore volume. Also, it is known that there is a certain correlation between the pore volume of the MOF and its gas adsorption property. Therefore, the MOF of this embodiment having the RHO-type topology can have a high gas adsorption property as compared with MOFs having other topologies.

[0014] In the MOF of this embodiment, a part of the 2-EtIm anion is substituted by a monocarboxylic acid anion. The monocarboxylic acid is preferably benzoic acid, acetic acid or formic acid, more preferably benzoic acid or acetic acid, and even more preferably benzoic acid. By substituting a part of the 2-EtIm anion with a monocarboxylic acid anion, a MOF having large pores can be obtained due to the template effect of the monocarboxylic acid. In particular, in the case of a monocarboxylic acid having a bulky group such as benzoic acid, the template effect of the monocarboxylic acid becomes more prominent, and a MOF having larger pores can be obtained.

[0015] In the MOF of this embodiment, the abundance ratio of the anion of the monocarboxylic acid in the ligand is preferably in the range of 1 to 20 mol% with respect to the total number of moles of the ligand, more preferably in the range of 3 to 20 mol%, and even more preferably in the range of 3 to 12 mol%. When the abundance ratio of the anion of the monocarboxylic acid in the ligand is within the above range, the MOF of this embodiment can have a high gas adsorption property.

[0016] The MOF of this embodiment usually has the following formula (I): Zn(2-EtIm x MCA y ) 2 It is represented by the formula (I). In the formula (I), 2-EtIm is a ligand which is an anion of 2-ethylimidazole, and MCA is a ligand which is an anion of a monocarboxylic acid. x is preferably in the range of 0.8 to 0.99, more preferably in the range of 0.8 to 0.97, and even more preferably in the range of 0.88 to 0.97. y is preferably in the range of 0.01 to 0.2, more preferably in the range of 0.03 to 0.2, and even more preferably in the range of 0.03 to 0.12. The MOF of this embodiment represented by the formula (I) can have high gas adsorption properties.

[0017] The gas adsorption property of the MOF of this embodiment is, for example, the N 2 adsorption isotherm is measured, and N 2 the N adsorption amount at a relative pressure of 50% 2 is calculated to evaluate it. The N 2 adsorption amount of the MOF of this embodiment at a relative pressure of 50% 2 is usually 180 mL (STP)·g -1 or more, particularly in the range of 180 to 410 mL (STP)·g -1 .

[0018] <2: Method for producing metal-organic framework> Another aspect of the present invention relates to a method for producing a metal-organic framework of an aspect of the present invention.

[0019] The method of this embodiment includes a mechanochemical reaction step. This step includes subjecting a zinc compound, 2-ethylimidazole (2-EtIm), and a monocarboxylic acid to a mechanochemical reaction in the presence of a solvent. In the present specification, the mechanochemical reaction means changing the crystal structure of the raw materials by applying mechanical stress such as grinding to the raw materials to advance the chemical reaction.

[0020] The zinc compound used in this step is preferably zinc oxide or zinc hydroxide, and more preferably zinc oxide. The zinc compounds exemplified above can have improved reactivity by using the solvents exemplified below. Therefore, by carrying out this step using the zinc compounds exemplified above, the mechanochemical reaction can proceed efficiently to obtain the MOF of one aspect of the present invention.

[0021] The monocarboxylic acid used in this step is preferably the compound exemplified above as a ligand. The presence of the monocarboxylic acid in the mechanochemical reaction system promotes the decomposition of the zinc compound as a raw material, while the decomposition of the product MOF is not promoted. Therefore, by adding the monocarboxylic acid exemplified above and carrying out this step, the decomposition of the zinc compound as a raw material can be promoted, and the MOF of one aspect of the present invention as a product can be obtained in a high yield.

[0022] The solvent used in this step is preferably a water-miscible organic solvent, more preferably N,N-dimethylformamide, methanol, N,N-diethylformamide, or ethanol, and even more preferably N,N-dimethylformamide or methanol. The solvents exemplified above can dissolve the raw materials 2-ethylimidazole (2-EtIm) and / or monocarboxylic acid. Therefore, by carrying out this step using the solvents exemplified above, the mechanochemical reaction can proceed efficiently to obtain the MOF of one aspect of the present invention.

[0023] In this process, the mechanochemical reaction preferably includes mixing raw materials using a ball mill. In the case of this embodiment, the rotation speed of the ball mill is preferably 50 rpm or more, more preferably in the range of 50 to 800 rpm, and even more preferably in the range of 100 to 500 rpm. Also, the mixing time by the ball mill is preferably 1 hour or more, and more preferably in the range of 1 to 3 hours. By carrying out this process under the above conditions, the mechanochemical reaction can proceed efficiently to obtain the MOF of one aspect of the present invention.

[0024] As described in detail above, the MOF of one aspect of the present invention has a RHO-type topology in which a part of the 2-EtIm anion as a ligand is substituted by a monocarboxylic acid anion, and thus can have a large pore volume and high gas adsorption properties. Therefore, the MOF of one aspect of the present invention can be applied to a gas adsorption material in a gas adsorption system, a gas separation system, or a gas storage system. Also, the manufacturing method of one aspect of the present invention can obtain the MOF of one aspect of the invention having the characteristics described above in a high yield. Therefore, the manufacturing method of one aspect of the present invention can efficiently provide a material applicable to the uses exemplified above.

Examples

[0025] Hereinafter, the present invention will be described more specifically using examples. However, the technical scope of the present invention is not limited to these examples.

[0026] <I: Production of Metal-Organic Framework> [I-1: Reagents] Zinc oxide (ZnO): Fujifilm Wako Pure Chemical Corporation 0.02 μm Practical Grade 95.0+% 2-Ethylimidazole (2-EtIm): Tokyo Chemical Industry Co., Ltd. >98.0% Benzoic acid (BA): Fujifilm Wako Pure Chemical Corporation 99.5+% Acetic acid (AA): Fujifilm Wako Pure Chemical Corporation 99.7+% Phosphoric acid (PA): FUJIFILM Wako Pure Chemical Corporation, 85.0+% Methanol (MeOH): Nacalai Tesque, Inc., Nacalai standard grade 1, ≧99.0% Ethanol (EtOH): Kanto Chemical Co., Inc., special grade, 94.8 to 95.8% N,N-Dimethylformamide (DMF): FUJIFILM Wako Pure Chemical Corporation, ultra-dehydrated for organic synthesis, 99.5+%

[0027] [I-2: Comparative Example 1-1] Into a 45 mL ball mill container, 1.22 g (15 mmol) of ZnO, 2.88 g (30 mmol) of 2-EtIm, a raw material containing 3 mL of DMF, and 50 g of zirconia balls with a diameter of Φ5 mm were added. The ball mill container was installed in a planetary ball mill apparatus. The rotation speed of the planetary ball mill apparatus was set to 100 rpm, and rotation was applied for 3 hours to mix the raw material mixture. The reaction mixture was recovered, and the zirconia balls were removed from the reaction mixture. 50 mL of ethanol was added to the reaction mixture and stirred. The reaction mixture was centrifuged at 16,000 rpm for 15 minutes, and the supernatant was removed. Centrifugation and removal of the supernatant were repeated a total of 4 times. The recovered precipitate was dried at 60 °C overnight under reduced pressure. By the above treatment, a powder was obtained.

[0028] [I-3: Comparative Examples 1-2, 1-3, 1-4, 1-5] Powders of Comparative Examples 1-2, 1-3, 1-4, or 1-5 were obtained in the same manner as Comparative Example 1-1, except that the rotation speed of the planetary ball mill apparatus was changed to 200, 300, 400, or 500 rpm.

[0029] [I-4: Comparative Example 2-1] Powder of Comparative Example 2-1 was obtained in the same manner as Comparative Example 1-1, except that the amount of 2-EtIm was changed to 3.60 g (37.5 mmol).

[0030] [I-5: Comparative Examples 2-2, 2-3, 2-4, 2-5] The powders of Comparative Example 2-2, 2-3, 2-4, or 2-5 were obtained in the same manner as Comparative Example 2-1, except that the rotational speed of the planetary ball mill apparatus was changed to 200, 300, 400, or 500 rpm.

[0031] [I-6: Comparative Example 3-1] The powder of Comparative Example 3-1 was obtained in the same manner as Comparative Example 1-1, except that the amount of DMF was changed to 6 mL.

[0032] [I-7: Comparative Examples 3-2, 3-3, 3-4, 3-5] The powders of Comparative Example 3-2, 3-3, 3-4, or 3-5 were obtained in the same manner as Comparative Example 3-1, except that the rotational speed of the planetary ball mill apparatus was changed to 200, 300, 400, or 500 rpm.

[0033] [I-8: Comparative Example 4-1] The powder of Comparative Example 4-1 was obtained in the same manner as Comparative Example 1-1, except that DMF was changed to 3 mL of MeOH.

[0034] [I-9: Comparative Examples 4-2, 4-3, 4-4, 4-5] The powders of Comparative Example 4-2, 4-3, 4-4, or 4-5 were obtained in the same manner as Comparative Example 4-1, except that the rotational speed of the planetary ball mill apparatus was changed to 200, 300, 400, or 500 rpm.

[0035] [I-10: Example 1-1] The powder of Example 1-1 was obtained in the same manner as Comparative Example 1-1, except that 0.916 g (7.5 mmol) of BA was added to the raw materials.

[0036] [I-11: Examples 1-2, 1-3, 1-4, 1-5] The powders of Example 1-2, 1-3, 1-4, or 1-5 were obtained in the same manner as Example 1-1, except that the rotational speed of the planetary ball mill apparatus was changed to 200, 300, 400, or 500 rpm.

[0037] [I-12: Example 2-1] The powder of Example 2-1 was obtained in the same manner as in Example 1-1, except that DMF was changed to 3 mL of MeOH.

[0038] [I-13: Examples 2-2, 2-3, 2-4, 2-5] The powders of Examples 2-2, 2-3, 2-4, or 2-5 were obtained in the same manner as in Example 2-1, except that the rotation speed of the planetary ball mill apparatus was changed to 200, 300, 400, or 500 rpm.

[0039] [I-14: Example 3-1] The powder of Example 3-1 was obtained in the same manner as in Comparative Example 1-1, except that 0.450 g (7.5 mmol) of AA was added to the raw materials.

[0040] [I-15: Examples 3-2, 3-3, 3-4, 3-5] The powders of Examples 3-2, 3-3, 3-4, or 3-5 were obtained in the same manner as in Example 3-1, except that the rotation speed of the planetary ball mill apparatus was changed to 200, 300, 400, or 500 rpm.

[0041] [I-16: Example 4-1] The powder of Example 4-1 was obtained in the same manner as in Example 3-1, except that DMF was changed to 3 mL of MeOH.

[0042] [I-17: Examples 4-2, 4-3, 4-4, 4-5] The powders of Examples 4-2, 4-3, 4-4, or 4-5 were obtained in the same manner as in Example 4-1, except that the rotation speed of the planetary ball mill apparatus was changed to 200, 300, 400, or 500 rpm.

[0043] [I-18: Comparative Example 5-1] The powder of Comparative Example 5-1 was obtained in the same manner as in Comparative Example 1-1, except that 0.865 g (7.5 mmol) of PA was added to the raw materials.

[0044] [I-19: Comparative Examples 5-2, 5-3, 5-4, 5-5] Powders of Comparative Example 5-2, 5-3, 5-4, or 5-5 were obtained in the same manner as Comparative Example 5-1, except that the rotational speed of the planetary ball mill apparatus was changed to 200, 300, 400, or 500 rpm.

[0045] [I-20: Comparative Example 6-1] Powder of Comparative Example 6-1 was obtained in the same manner as Comparative Example 5-1, except that DMF was changed to 3 mL of MeOH.

[0046] [I-21: Comparative Examples 6-2, 6-3, 6-4, 6-5] Powders of Comparative Example 6-2, 6-3, 6-4, or 6-5 were obtained in the same manner as Example 6-1, except that the rotational speed of the planetary ball mill apparatus was changed to 200, 300, 400, or 500 rpm.

[0047] <II: Analysis of Crystal Structure of Metal-Organic Framework>[ X-ray diffraction measurements were performed on the powders of the products obtained in Comparative Examples 1-1 to 6-5 and Examples 1-1 to 4-5, respectively. The measuring apparatus and measuring conditions are shown below. Measuring apparatus: RINT RAPID II (Rigaku Corporation) Measuring conditions: Voltage 50 V, current 100 mA, collimator diameter φ0.3, sample angle ω 5°

[0048] For the known MOF, RHO-type Zn(2-EtIm) 2 (reported under the name MAF-6) and ANA-type Zn(2-EtIm) 2 (reported under the name MAF-5 or ZIF-14), and for the raw material ZnO, the X-ray diffraction pattern was simulated by calculation and compared with the X-ray diffraction patterns of the powders of the products in the comparative examples and examples. The X-ray diffraction patterns of the powders of the products in Examples 1, 2, 3, and 4 are shown in FIGS. 1, 2, 3, and 4, respectively. In each figure, the horizontal axis indicates the 2θ value (°), and the vertical axis indicates the intensity (a.u.). Also, in each figure, 100 rpm, 200 rpm, 300 rpm, 400 rpm, or 500 rpm indicates the rotational speed of the planetary ball mill apparatus during production. RHO-type, ANA-type, or ZnO refers to RHO-type Zn(2-EtIm)2 1. ANA-type Zn(2-EtIm) 2 and the simulation results of the X-ray diffraction patterns calculated for ZnO are shown.

[0049] From the X-ray diffraction pattern of the powder of the product of Comparative Example 1, it became clear that the product at 100 rpm was a mixture of ZnO as a raw material and RHO-type MOF (the X-ray diffraction pattern is not shown). When the rotation speed of the planetary ball mill apparatus during production increased, the peak intensity of ZnO in the X-ray diffraction pattern decreased. Therefore, it is presumed that the production amount of MOF increases as the rotation speed of the planetary ball mill apparatus during production increases. On the other hand, when the rotation speed of the planetary ball mill apparatus during production increased to 200 rpm or more, the peak intensity of ANA-type MOF in the X-ray diffraction pattern increased. From these results, it is presumed that when the rotation speed of the planetary ball mill apparatus during production is low, RHO-type MOF is mainly produced, but as the rotation speed increases, the production amount of ANA-type MOF increases more than that of RHO-type MOF. The same tendency was also confirmed in the X-ray diffraction patterns of the powders of the products of Comparative Examples 2, 3, and 4 (the X-ray diffraction patterns are not shown).

[0050] From the X-ray diffraction pattern of the powder of the product of Example 1, it became clear that the product was a single phase of RHO-type MOF regardless of the rotation speed of the planetary ball mill apparatus during production (Figure 1). In Example 2, a slight presence of ZnO was confirmed in the products with a rotation speed of 100 rpm or 300 rpm of the planetary ball mill apparatus during production, but the main phase was RHO-type MOF (Figure 2). In Example 3 and Example 4, as the rotation speed of the planetary ball mill apparatus during production increased, a small amount of ANA-type MOF was produced (Figure 3 and Figure 4).

[0051] In the X-ray diffraction pattern of the powder of the product of Comparative Example 5, peaks not attributable to the RHO type or the ANA type were observed (the X-ray diffraction pattern is not shown). In the X-ray diffraction pattern of the powder of the product of Comparative Example 6, in addition to the peaks observed in Comparative Example 5, as the rotation speed of the planetary ball mill apparatus during production increased, a slight peak of the ANA type MOF was observed (the X-ray diffraction pattern is not shown). From these results, it became clear that although the addition of PA promotes the decomposition and reaction of ZnO, the addition of monocarboxylic acids such as BA and AA is preferable for the formation of the RHO type MOF.

[0052] From the peak intensities in the X-ray diffraction patterns of the powders of the products of the Examples and Comparative Examples, the abundance ratios of the RHO type MOF, the ANA type MOF, and ZnO as the raw material were calculated. The abundance ratio of the RHO type MOF with respect to the total weight of the products of the Examples and Comparative Examples is shown in FIG. 5. In the figure, the horizontal axis is the rotation speed (rpm) of the planetary ball mill apparatus during production, and the vertical axis is the abundance ratio (wt%) of the RHO type MOF.

[0053] As shown in FIG. 5, in the products of Comparative Examples 1 to 4, although the abundance ratio of ZnO decreased as the rotation speed of the planetary ball mill apparatus during production increased, the abundance ratio of the RHO type MOF decreased because the formation of the ANA type MOF became advantageous. On the other hand, in the products of Examples 1 to 4, the RHO type MOF was obtained as the main phase under all conditions.

[0054] <III: Characterization of Metal-Organic Frameworks> [III-1: Evaluation of Pore Volume of MOF] For the products of Examples 1 to 4 and Comparative Examples 1 to 4, after pretreatment, N 2 adsorption isotherms were measured. Also, the N 2 adsorption amount at a relative pressure of 50% was determined. The pretreatment apparatus, pretreatment conditions, measurement apparatus, and measurement conditions used in this measurement are shown below. 2 Pretreatment apparatus: BELPREP vacII (MicrotracBEL Corp.) Pretreatment conditions: Vacuum degree < 10 -2 -2Pa, heated at 160 °C for 6 hours Measuring device: BELSORP max (Microtrac BEL Corporation) Measuring conditions: temperature 77 K, N 2 Adsorption amount of N at a relative pressure from 0 to 99% was measured 2

[0055] The N adsorption / desorption isotherms of the products of Examples 1 to 4 and Comparative Examples 1 to 4 were determined 2 The N adsorption amount determined by measuring the adsorption / desorption isotherm 2 The adsorption amount is shown in Fig. 6. In the figure, the horizontal axis represents the rotation speed (rpm) of the planetary ball mill device during production, and the vertical axis represents the N 2 The N adsorption amount determined by measuring the adsorption / desorption isotherm 2 The N adsorption amount at a relative pressure of 50% 2 Adsorption amount (mL (STP)·g -1 )

[0056] As shown in Fig. 6, compared with the products of Comparative Examples 1 to 4, in the products of Examples 1 to 4, the N 2 Adsorption amount tended to be high. In the case of the products of Comparative Examples 1 to 4, when the rotation speed of the planetary ball mill device during production was 400 rpm or 500 rpm, the abundance ratio of the RHO-type MOF was low (Fig. 5), but the N 2 Adsorption amount was not so low. The ANA-type MOF has about half the pore volume of the RHO-type MOF. Therefore, when the ANA-type MOF is formed instead of the RHO-type MOF, it is presumed that a certain degree of N 2 Adsorption amount is shown. From these results, it is presumed that the addition of monocarboxylic acid (especially benzoic acid) promotes the decomposition of ZnO and the formation of the RHO-type MOF

[0057] [III-2: Composition analysis of MOF] The products of Examples 1 to 4 were decomposed and dissolved in a heavy solvent. The 1 1H-NMR spectrum of the obtained solution was measured, and the ratios of 2-ethylimidazole and monocarboxylic acid (benzoic acid or acetic acid) contained in the MOF were determined from the integral ratio of the spectrum. The decomposition conditions, measuring device, and measuring conditions used in this measurement are shown below ​Decomposition conditions: The product is decomposed with a deuterium sulfate (D 2 SO 4 ) solution in heavy water (D 2 O). Measuring device: INOVA300 (Agilent Technologies)

[0058] The composition of the RHO-type MOF determined from the 1 H-NMR spectra of the products of Examples 1 to 4 is shown in Table 1.

[0059]

Table 1

[0060] The monocarboxylic acid added during synthesis becomes a monovalent organic anion. Therefore, it is presumed that the monocarboxylic acid is incorporated into the structure of the MOF in a form that replaces a part of 2-ethylimidazole.

[0061] Note that the present invention is not limited to the above-described examples and includes various modifications. For example, the above-described examples have been described in detail for easy understanding of the present invention and are not necessarily limited to those having all the configurations described. Also, it is possible to add, delete, and / or replace a part of the configuration of each example with other configurations.

Claims

1. A metal-organic framework composed of a metal ion that is a zinc cation and a ligand that is an anion of 2-ethylimidazole (2-EtIm) or a monocarboxylic acid, having a RHO-type topology in which a part of the 2-EtIm anion is substituted by the monocarboxylic acid anion.

2. The metal-organic framework according to Claim 1, wherein the monocarboxylic acid is benzoic acid or acetic acid.

3. The metal-organic framework according to Claim 1, wherein the abundance ratio of the anion of the monocarboxylic acid in the ligand is in the range of 1 to 20 mol% with respect to the total number of moles of the ligand.

4. A mechanochemical reaction step of subjecting a zinc compound, 2-ethylimidazole (2-EtIm), and a monocarboxylic acid to a mechanochemical reaction in the presence of a solvent. A method for producing the metal-organic framework according to Claim 1, comprising the step.

5. The method according to Claim 4, wherein the mechanochemical reaction includes mixing the raw materials using a ball mill.

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