JP7752987B2 - Porous zinc complex and method for producing the same - Google Patents

Description

The present invention relates to a porous zinc complex produced in a hydrophobic atmosphere and a method for producing the same. The porous zinc complex produced by this method can be used as a catalyst for various reactions that prefer an inert atmosphere, and can provide a catalyst with higher activity than porous zinc complexes produced in a hydrophilic atmosphere.

Known porous materials include carbon materials such as activated carbon and mesoporous carbon, inorganic materials such as mesoporous silica and zeolites, and porous metal complexes such as metal-organic frameworks. Among these, porous metal complexes composed of metal ions or metal cluster ions and ligand ions are polymers that form uniform pore structures at the molecular level, have narrow pore distributions, and have a high specific surface area that surpasses other porous materials. For this reason, they have attracted attention as reaction catalysts, and many examples of introducing functional groups onto their surfaces have been reported (see, for example, Non-Patent Document 1).

Porous metal complexes are produced by reacting inorganic salt hydrates, such as metal nitrate hydrates, with organic compounds, which serve as raw materials for organic ligands, in a hydrophilic solvent, such as N,N-dimethylformamide or water, but surface hydroxyl groups and adsorbed water remain (see, for example, Non-Patent Document 2). Therefore, when used as a reaction catalyst that prefers an inert atmosphere, it is necessary to inactivate the surface hydroxyl groups and remove the adsorbed water, which can cause catalyst deactivation.
A commonly known method for this is drying under reduced pressure in a heated atmosphere. For example, it has been reported that a porous zinc complex composed of zinc ions and 2-methylimidazole, which is used as a catalyst in the amidation reaction between amines and carboxylic acids (see, for example, Non-Patent Document 3) and the Knoevenagel condensation reaction between malononitrile and aldehydes (see, for example, Non-Patent Document 4), can be dried under reduced pressure in a heated atmosphere.

Journal of Nanoscience and Nanotechnology, (2013) 13, 2307-2312 Journal of Physical Chemistry Letters, (2010) 1(1), 349-353 Synlett, (2018) 29(12), 1593-1596 Journal of Solid State Chemistry, (2017) 256,27-32 Energy & Environmental Science, (2014) 7, 2232-2238

Porous zinc complexes have a limited heat resistance temperature. For example, in porous zinc complexes composed of zinc ions and 2-methylimidazole, the metal-ligand bond breaks at approximately 400°C and becomes completely non-porous at 600°C (see, for example, Non-Patent Document 5). For this reason, reduced-pressure drying treatments aimed at deactivating surface hydroxyl groups and removing adsorbed water are generally performed at temperatures between 100°C and 400°C, but these temperatures do not completely remove the surface hydroxyl groups and adsorbed water. Thus, with conventional methods for producing porous zinc complexes, it has been extremely difficult to deactivate the surface hydroxyl groups and remove the adsorbed water contained in the porous zinc complex. No porous zinc complexes free of the surface hydroxyl groups and adsorbed water that cause the complex's deactivation have been reported to date. Therefore, the easy and efficient production of such porous zinc complexes using industrially readily available raw materials and the high activity of catalysts using such complexes remain challenges.

In light of the above-mentioned problems, the inventors focused on organic zinc compounds as raw materials and investigated the production of porous zinc complexes in a hydrophobic atmosphere using aprotic solvents. They were able to solve the above-mentioned problems using the following means, thereby completing the present invention.

That is, the present invention relates to the following.
[1] A method for producing a porous zinc complex, comprising reacting an organic zinc compound represented by the following general formula (1) with one or more organic ligand raw materials selected from the group consisting of imidazole compounds having at least one imidazolyl group in the molecule and carboxylic acid compounds having at least two carboxy groups in the molecule, in an aprotic solvent in the presence of an inert gas:
M ₁ -Zn-M ₂ (1)
(In formula (1), _M1 and _M2 each independently represent a linear, branched, or cyclic alkyl group having 20 or less carbon atoms, or a cyclic hydrocarbon group including an aromatic group having 20 or less carbon atoms.)
[2] The production method according to [1], wherein the organic ligand raw material is 2-methylimidazole, 2-ethylimidazole, benzimidazole, 1,4-benzenedicarboxylic acid, or 2,5-dihydroxy-1,4-benzenedicarboxylic acid.
[3] The method according to [1] or [2], wherein the organozinc compound is diethylzinc, dipropylzinc, or diisopropylzinc.
[4] The production method according to any one of the above [1] to [3], wherein the aprotic solvent is one solvent or a mixed solvent of two or more solvents selected from the group consisting of heterocyclic aromatic solvents, furan solvents, thiophene solvents, nitrile solvents, lactam solvents, amide solvents, carbamide solvents, ketone solvents, sulfoxide solvents, ester solvents, and ether solvents.
[5] The production method according to any one of the above [1] to [4], wherein the aprotic solvent is pyridine, dimethyl sulfoxide, or N,N-dimethylformamide.
[6] The method according to any one of the above [1] to [5], wherein the water content in the aprotic solvent is 50 ppm or less.
[7] The method according to any one of the above [1] to [6], wherein the porous zinc complex has an oxygen atom concentration of 2.5 atm% or less, calculated from the photoelectron intensities of O1s orbital (505 to 545 eV), C1s orbital (270 to 295 eV), N1s orbital (375 to 415 eV), and Zn2p3/2 orbital (995 to 1,035 eV) obtained by X-ray photoelectron spectroscopy (XPS), and the ratio of the number of oxygen atoms to the number of zinc atoms is 20 atm% or less.
[8] A porous zinc complex having an oxygen atomic concentration of 2.5 atm% or less, calculated from the photoelectron intensities of O1s orbital (505-545 eV), C1s orbital (255-295 eV), N1s orbital (375-415 eV), and Zn2p orbital (995-1,035 eV) obtained by X-ray photoelectron spectroscopy (XPS), and a ratio of the number of oxygen atoms to the number of zinc atoms of 20 atm% or less.
[9] The porous zinc complex according to [8], which has a BET specific surface area of 600 m ² /g or more and a thermal decomposition temperature of 350° C. or more.
[10] The porous zinc complex according to [8] or [9], which contains 2-methylimidazole zinc salt.
[11] The porous zinc complex according to [10], wherein the porous zinc complex contains nanoparticles having an average particle size of 10 to 30 nm as measured using a transmission electron microscope (TEM).
[12] A catalyst comprising the porous zinc complex according to any one of [8] to [11] above.

According to the present invention, it is possible to produce a novel porous zinc complex that does not contain surface hydroxyl groups or adsorbed water, which cause inactivation of the porous zinc complex.
The porous zinc complex of the present invention is suitable because it exhibits high activity in reactions under an inert atmosphere.
Furthermore, the method for producing a porous zinc complex of the present invention can omit the long-term reduced-pressure drying treatment under heating and calcination that is performed in conventional production methods to remove surface hydroxyl groups and adsorbed water to a certain amount, which is expected to reduce capital investment costs and fuel costs and shorten the production process.

The graph shows the nitrogen adsorption and desorption amounts of the porous zinc complexes of Example 1 and Comparative Example 1, with the X-axis (horizontal axis) representing relative pressure (P/P ₀ ) and the Y-axis (vertical axis) representing the N ₂ adsorption amount (unit: mL/g). 1 shows the TG curve of Example 1, with the X-axis (horizontal axis) representing temperature (unit: ° C.) and the Y-axis (vertical axis) representing the weight loss rate (unit: wt %). 1 shows the TG curve of Comparative Example 1, with the X-axis (horizontal axis) representing temperature (unit: ° C.) and the Y-axis (vertical axis) representing the weight loss rate (unit: wt %). 1 shows a TEM image of Example 1, where the white bar in the left image indicates a length of 50 nm and the white bar in the right image indicates a length of 20 nm. The right image is an enlarged view of the black frame in the left image. 1 shows a TEM image of Comparative Example 1, where the white bar in the left image indicates a length of 50 nm and the white bar in the right image indicates a length of 20 nm. The right image is an enlarged view of the black frame (surrounded by a dashed line) in the left image. 1 shows the X-ray photoelectron spectroscopy (hereinafter sometimes abbreviated as "XPS") spectrum patterns of the O1s orbital of the porous zinc complexes in Example 1 and Comparative Example 1, where the X-axis (horizontal axis) represents the binding energy (unit: eV) and the Y-axis (vertical axis on the right) represents the intensity (unit: a.u. (arbitrary unit)). 1 shows XPS spectrum patterns of the Cls orbitals of the porous zinc complexes in Example 1 and Comparative Example 1, where the X axis (horizontal axis) represents the binding energy (unit: eV) and the Y axis (vertical axis on the right) represents the intensity (unit: a.u. (arbitrary unit)). 1 shows the XPS spectrum patterns of the N1s orbitals of the porous zinc complexes in Example 1 and Comparative Example 1, where the X axis (horizontal axis) represents the binding energy (unit: eV) and the Y axis (vertical axis on the right) represents the intensity (unit: a.u. (arbitrary unit)). 1 shows XPS spectral patterns of the Zn 2p orbital of the porous zinc complexes in Example 1 and Comparative Example 1, where the X axis (horizontal axis) represents binding energy (unit: eV) and the Y axis (vertical axis on the right) represents intensity (unit: a.u. (arbitrary unit)). 1 shows a plot of the change over time in the conversion of N,N-diphenylamine and the yield of the product N,N-diphenylformamide in Example 2 and Comparative Example 2, where the X-axis (horizontal axis) represents the reaction time (unit: hours) and the Y-axis (vertical axis) represents the yield/conversion (unit: %). 1 shows the adsorption and desorption amounts of nitrogen for the porous zinc complex of Example 3, with the X axis (horizontal axis) representing relative pressure (P/P ₀ ) and the Y axis (vertical axis) representing the N ₂ adsorption amount (unit: mL/g). 1 shows the TG curve of Example 3, with the X-axis (horizontal axis) representing temperature (unit: ° C.) and the Y-axis (vertical axis) representing the weight loss rate (unit: wt %). The left side of the figure shows an SEM image of Example 3, where the white bar in the figure indicates a length of 50 μm, and the right side of the figure is an enlarged view of the square part in the left side of the figure, where the white bar in the figure indicates a length of 1 μm. 1 shows the adsorption and desorption amounts of nitrogen for the porous zinc complex of Example 4, with the X axis (horizontal axis) representing relative pressure (P/P ₀ ) and the Y axis (vertical axis) representing the N ₂ adsorption amount (unit: mL/g). 1 shows the TG curve of Example 4, with the X-axis (horizontal axis) representing temperature (unit: ° C.) and the Y-axis (vertical axis) representing the weight loss rate (unit: wt %). The left side of the figure shows an SEM image of Example 4, where the white bar in the figure indicates a length of 50 μm, and the right side of the figure is an enlarged view of the square part in the left side of the figure, where the white bar in the figure indicates a length of 1 μm. 1 shows the adsorption and desorption amounts of nitrogen for the porous zinc complex of Example 5, with the X axis (horizontal axis) representing relative pressure (P/P ₀ ) and the Y axis (vertical axis) representing the N ₂ adsorption amount (unit: mL/g). 1 shows the TG curve of Example 5, with the X-axis (horizontal axis) representing temperature (unit: ° C.) and the Y-axis (vertical axis) representing the weight loss rate (unit: wt %). The left side of the figure shows an SEM image of Example 5, where the white bar in the figure indicates a length of 50 μm, and the right side of the figure is an enlarged view of the square part in the left side of the figure, where the white bar in the figure indicates a length of 1 μm. 1 shows the adsorption and desorption amounts of nitrogen for the porous zinc complex of Example 6, with the X axis (horizontal axis) representing relative pressure (P/P ₀ ) and the Y axis (vertical axis) representing the N ₂ adsorption amount (unit: mL/g). 1 shows the TG curve of Example 6, with the X-axis (horizontal axis) representing temperature (unit: ° C.) and the Y-axis (vertical axis) representing the weight loss rate (unit: wt %). 1 shows a TEM image of Example 6, in which the white bar indicates a length of 100 nm. 1 shows the adsorption and desorption amounts of nitrogen for the porous zinc complex of Example 7, with the X axis (horizontal axis) representing relative pressure (P/P ₀ ) and the Y axis (vertical axis) representing the N ₂ adsorption amount (unit: mL/g). 1 shows the TG curve of Example 7, with the X-axis (horizontal axis) representing temperature (unit: ° C.) and the Y-axis (vertical axis) representing the weight loss rate (unit: wt %). The left side of the figure shows an SEM image of Example 7, where the white bar in the figure indicates a length of 50 μm, and the right side of the figure is an enlarged view of the square part in the left side of the figure, where the white bar in the figure indicates a length of 1 μm.

Preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.
The porous zinc complex of the present invention is produced using hydrophobic raw materials under a hydrophobic atmosphere. That is, it is produced by reacting an organic zinc compound with an organic ligand raw material in an aprotic solvent under an inert atmosphere. Therefore, the surface structure is significantly different from that of conventional production methods.

The surface structure of the porous zinc complex of the present invention can include a structural unit represented by general formula (2-1). This structural unit is composed of zinc-organic ligand bonds, and the presence of surface hydroxyl groups and adsorbed water represented by zinc-hydroxyl group bonds in structural units represented by general formula (2-2) formed by conventional manufacturing methods is extremely low. The presence of surface hydroxyl groups and adsorbed water can be estimated from the surface oxygen atom concentration measured by X-ray photoelectron spectroscopy (XPS). For example, when the organic ligand raw material is an imidazole compound, the oxygen atom concentration is 2.5 atm% or less, more preferably 1 atm% or less, and particularly preferably 0.1 atm% or less.

(In general formula (2-1), n represents an integer of 2 or more.)

(In general formula (2-2), n represents an integer of 2 or more.)

The porous zinc complex of the present invention is formed by linking units having a structure in which three or more organic ligands are regularly coordinated to a zinc ion Zn ²⁺ or a zinc-oxygen cluster as shown in formula (3-1), to form an aggregate of high molecular weight zinc salts.
The zinc-oxygen cluster is a cation in which oxygen is coordinated to two or more zinc atoms in a bridging manner, and an example thereof is a tetrahedral Zn ₄ O ⁶⁺ structure represented by the general formula (4-1).
Examples of the unit include, for example, when the organic ligand is 2-methylimidazole, a structure in which four 2-methylimidazoles are coordinated to a zinc ion represented by the general formula (3-2), and when the organic ligand is 1,4-benzenedicarboxylic acid, a structure in which six 1,4-benzenedicarboxylic acids are coordinated to a zinc-oxygen cluster of Zn ₄ O ⁶⁺ represented by the general formula (4-2).
The zinc salt aggregate includes a structure in which the ligand is coordinated to two or more zinc ions or two or more zinc-oxygen clusters in a bridging manner, and the zinc ions or zinc-oxygen clusters and the ligand are bonded to each other crosswise.

Zn ²⁺ (3-1)

There is no particular limitation on the crystal structure of the porous zinc complex of the present invention, but specific examples of zinc salts that constitute the porous zinc complex include 2-methylimidazole zinc salt, 2-ethylimidazole zinc salt, 4,5-dichloroimidazole salt, benzimidazole zinc salt, imidazole-5-chlorobenzimidazole zinc salt, 2-methylimidazole-5-chlorobenzimidazole zinc salt, 3-amino-1,2,4-triazole zinc salt, zinc oxalate, zinc fumarate, glycine-alanine zinc salt, and 2,5-furan. Zinc dicarboxylates, zinc acetylenedicarboxylates, zinc benzenedicarboxylates, zinc 2-bromo-1,4-dicarboxylates, zinc 2-amino-1,4-dicarboxylates, zinc 2-(propoxy)-1,4-dicarboxylates, zinc 2-(pentoxy)-1,4-dicarboxylates, zinc 2-(cyclobutyl)-1,4-dicarboxylates, zinc 1,4-naphthalenedicarboxylates, zinc 4,4'-biphenyldicarboxylates, zinc 4,5,6,10-tetrahydropyrene-2,7-dicarboxylate salt, pyrene-2,7-dicarboxylic acid zinc salt, 4,4'-((3,4-dioxocyclobutene-1,2-diyl)bis(azanediyl))dibenzenecarboxylic acid zinc salt, 2',5',-dimethyl-3,3''-dihydroxy-[1,1':4'1''-terphenyl]-4,4''-dicarboxylic acid zinc salt, 2,5-(allyloxy)-1,4-benzenedicarboxylic acid zinc salt, 2,5-(benzyloxy)-1,4-benzenedicarboxylic acid zinc salt, terphenyl-4,4''-dicarboxylic acid zinc salt, 1, 3,5-tris(4'-carboxyphenyl)benzene zinc salt, 2-methylimidazole-5-chlorobenzimidazole zinc salt, 1,3,5-benzenetricarboxylic acid zinc salt, 1,3,5-tris(4'-carboxyphenylethynyl)benzene zinc salt, 1,3,5-tris(4'-carboxy[1,1'-biphenyl]-4-yl)benzene zinc salt, 2,5-dihydroxy-1,4-benzenedicarboxylic acid zinc salt, 1,4-naphthalenedicarboxylic acid-1,4-diazabicyclo[2.2.2. ]octane zinc salt, benzenedicarboxylic acid-bipyridine zinc salt, 1,3,5-tris(4'-carboxyphenyl)benzene-2,6-naphthalenedicarboxylic acid zinc salt, 1,3,5-tris(4'-carboxyphenylethynyl)benzene-bisphenyl-4,4''-dicarboxylic acid zinc salt, 1,3,5-tris(4'-carboxyphenylethynyl)benzene-benzenedicarboxylic acid zinc salt, 1,3,5-tris(4'-carboxyphenylethynyl)benzene-2-amino-1,4-benzenedicarboxylic acid zinc salt, 4,4',4''-triazine-1,3,5-tolyl-tri-4-aminobenzenecarboxylic acid-1,4-diazabicyclo[2.2.2.]octane zinc salt, tetrathiafulvalenetetrabenzenecarboxylic acid zinc salt, and the like can be exemplified.
When a porous zinc complex is used as a reaction catalyst, an optimal porous zinc complex can be designed depending on the type of reaction, taking into consideration the ligand, specific surface area, pore diameter, and pore structure. For example, in the formylation reaction of a secondary amine, 2-methylimidazole zinc salt is preferred from the viewpoint of having a Lewis basic ligand in the vicinity of the Lewis acidic zinc ion.

M ₁ and M ₂ represented by general formula (1) of the organozinc compound will be explained below.
M ₁ and M ₂ are each independently a straight chain, branched chain, or cyclic hydrocarbon having 1 to 20 carbon atoms, or a cyclic hydrocarbon containing an aromatic group having 20 or less carbon atoms, but are not limited thereto.

Specific examples of the alkyl group having 20 or less carbon atoms and representing _M1 or _M2 include a methyl group, an ethyl group, a propyl group, an isopropyl group, a cyclopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclobutyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a cyclopentadienyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 1,2-dimethylpropyl group, a 1-ethylpropyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a 4-methylcyclohexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, an icosyl group, a phenyl group, a benzyl group, a naphthyl group, an adamantyl group, an indecyl group, a phenanthresyl group, a fluorenyl group, and a triphenylenyl group.

Specific examples of the organozinc compound represented by general formula (1) include dimethylzinc, diethylzinc, dipropylzinc, diisopropylzinc, dicyclopropylzinc, dibutylzinc, diisobutylzinc, disec-butylzinc, ditert-butylzinc, dicyclobutylzinc, dipentylzinc, diisopentylzinc, dineopentylzinc, ditert-pentylzinc, dicyclopentadienylzinc, di(1-methylbutyl)zinc, di(2-methylbutyl)zinc, di(1,2-dimethylpropyl)zinc, di Examples include (1-ethylpropyl)zinc, di(cyclopentyl)zinc, dihexylzinc, di(cyclohexyl)zinc, di(4-methylcyclohexyl)zinc, diheptylzinc, dioctylzinc, dinonylzinc, didecylzinc, diundecylzinc, didodecylzinc, ditridecylzinc, diicosylzinc, diphenylzinc, dibenzylzinc, dinaphthylzinc, diadamantylzinc, diindecylzinc, diphenanthresylzinc, difluorenylzinc, and ditriphenylenylzinc.
From the viewpoint of inexpensive production of a porous zinc complex, dimethyl zinc, diethyl zinc, dipropyl zinc, diisopropyl zinc, dibutyl zinc, diisobutyl zinc, disec-butyl zinc, and ditert-butyl zinc are preferred, diethyl zinc, dipropyl zinc, and diisopropyl zinc are more preferred, and diethyl zinc is particularly preferred.

We will now explain the organic ligand raw material. The organic ligand raw material is an imidazole compound having at least one imidazolyl group in the molecule, or a carboxylic acid compound having at least two carboxy groups in the molecule.

There are no particular limitations on the imidazole compound, but specific examples of the imidazole compound include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 2-isopropylimidazole, 2-butylimidazole, 2-isobutylimidazole, 2-sec-butylimidazole, 2-tert-butylimidazole, 2-pentylimidazole, 2-hexylimidazole, and 2-heptylimidazole. Imidazole, 2-octylimidazole, 2-nonylimidazole, 2-decylimidazole, 2-dodecylimidazole, 2-phenylimidazole, 2-benzylimidazole, 2-naphthylimidazole, 2-(1-naphthylmethyl)imidazole, 2-anthracelimidazole, 2-tetracylimidazole, 2-pentacylimidazole, 2-triphenylenylimidazole, 2-fluoroimidazo 2-chloroimidazole, 2-bromoimidazole, 2-iodoimidazole, 4-methylimidazole, 4-ethylimidazole, 4-phenylimidazole, 4-benzylimidazole, 4-fluoroimidazole, 4-chloroimidazole, 4-bromoimidazole, 4-iodoimidazole, 5-methylimidazole, 5-ethylimidazole, 5-phenylimidazole, 5-benzylimidazole , 5-fluoroimidazole, 5-chloroimidazole, 5-bromoimidazole, 5-iodoimidazole, 4,5-dimethylimidazole, 4,5-diethylimidazole, 4,5-diphenylimidazole, 4,5-difluoroimidazole, 4,5-dichloroimidazole, 4,5-dibromoimidazole, 4,5-diiodoimidazole, 4-methyl-2-phenylimidazole, 2,4,5-trimethyl Imidazole, 2,4,5-triethylimidazole, 2,4,5-triphenylimidazole, 2,4,5-trifluoroimidazole, 2,4,5-trichloroimidazole, 2,4,5-tribromoimidazole, 2,4,5-triiodoimidazole, benzimidazole, 2-methylbenzimidazole, 2-ethylbenzimidazole, 2-fluorobenzimidazole, 2-chlorobenzimidazole , 2-bromobenzimidazole, 2-iodobenzimidazole, 4-methylbenzimidazole, 4-ethylbenzimidazole, 4-fluorobenzimidazole, 4-chlorobenzimidazole, 4-bromobenzimidazole, 4-iodobenzimidazole, 5-methylbenzimidazole, 5-ethylbenzimidazole, 5-fluorobenzimidazole, 5-chlorobenzimidazole, 5-bromobenzimidazole, 4-iodobenzimidazole, 5-methylbenzimidazole, 5-ethylbenzimidazole, 5-fluorobenzimidazole, 5-chlorobenzimidazole, 5-bromobenzimidazole, 5-iodo ... 5,6-Dimethylbenzimidazole, 5,6-Diethylbenzimidazole, 5,6-Difluorobenzimidazole, 5,6-Dichlorobenzimidazole, 6-Bromobenzimidazole, 6-Iodobenzimidazole, 5,6-Dimethylbenzimidazole, 5,6-Diethylbenzimidazole, 5,6-Difluorobenzimidazole, 5,6-Dichlorobenzimidazole Examples include 5,6-dibromobenzimidazole, 5,6-diiodobenzimidazole, 5,6-dichloro-2-methylbenzimidazole, 5,6-dibromo-2-methylbenzimidazole, 2-(2-chlorophenyl)benzimidazole, 2-(2-bromophenyl)benzimidazole, and 2,2'-biimidazole, with 2-methylimidazole and 2-ethylimidazole being preferred.

There are no particular limitations on the carboxylic acid compound, but specific examples of carboxylic acid compounds include oxalic acid, fumaric acid, 1,4-butanedicarboxylic acid, pentane-3,3-carboxylic acid, 1,6-hexanedicarboxylic acid, decanedicarboxylic acid, 1,8-heptadecanedicarboxylic acid, 1,9-heptadecanedicarboxylic acid, heptadecanedicarboxylic acid, 1,3-butadiene-1,4-dicarboxylic acid, acetylenedicarboxylic acid, 2-(propoxy)-1,4-dicarboxylic acid, 2-(pentoxy)-1,4-dicarboxylic acid, 2-(cyclobutyl)-1,4-dicarboxylic acid, cyclobutane-1,1-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, cyclohexene-2,3-dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, heptane-1,7-dicarboxylic acid, 3,6-dioxaoctanedicarboxylic acid, 3,5-cyclohexadiene-1,2-dicarboxylic acid, and octanedica. Carboxylic acid, 1-nonene-6,9-dicarboxylic acid, hexatriacontanedicarboxylic acid, tetradecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, eicosenedicarboxylic acid, 3,6,9-trioxaundecanedicarboxylic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 2-bromo-1,4-benzenedicarboxylic acid, 2-hydroxy-1,4-benzenedicarboxylic acid, 2,5-dichloro-1,4-benzenedicarboxylic acid, 2,5-dihydroxy-1,4-benzenedicarboxylic acid, 5-hydroxy-1,3-benzenedicarboxylic acid, 5-t-butyl-1,3-benzenedicarboxylic acid, 2,5-dimethyl-1,4-benzenedicarboxylic acid, 2,5-(allyloxy)-1,4-benzenedicarboxylic acid, 2,5-(benzyloxy)-1,4-benzenedicarboxylic acid, 2',5',-dimethyl-3,3'' -dihydroxy-[1,1':4'1''-terphenyl]-4,4''-dicarboxylic acid, 2-nitro-1,4-benzenedicarboxylic acid, 2-amino-1,4-benzenedicarboxylic acid, 1-methylpyrrole-3,4-dicarboxylic acid, 1-benzyl-1H-pyrrole-3,4-dicarboxylic acid, 2,5-furandicarboxylic acid, pyridine-2,3-dicarboxylic acid, imidazole-2,4-dicarboxylic acid, imidazole-4,5-dicarboxylic acid, 2-methylimidazole-4,5-dicarboxylic acid, 2-isopropylimidazole-4,5-dicarboxylic acid, 3,4-pyrazole dicarboxylic acid, 3,5-pyrazole dicarboxylic acid, pyridine-2,5-dicarboxylic acid, 2,6-pyridine dicarboxylic acid, 3,4-pyridine dicarboxylic acid, 5-ethyl-2,3-pyridine dicarboxylic acid, pyrazine-2,3-dicarboxylic acid, 5,6-dimethyl-2,3-pyrazine-dicacid carboxylic acid, 3,4-quinolinedicarboxylic acid, 7,8-quinolinedicarboxylic acid, 7-chloro-4-hydroxyquinoline-2,8-dicarboxylic acid, 7-chloroquinoline-3,8-dicarboxylic acid, 2-methylquinoline-3,4-dicarboxylic acid, quinoline-2,4-dicarboxylic acid, quinoxaline-2,3-dicarboxylic acid, 6-chloroquinoxaline-2,3-dicarboxylic acid, 7-chloro-8-methylquinoline-2,3-dicarboxylic acid, 7-chloro-3-methylquinoline-6,8-dicarboxylic acid, 2,2'-biquinoline-4,4'-dicarboxylic acid, 4,4'-diaminephenylmethane-3,3'-dicarboxylic acid, furan-2,5-dicarboxylic acid, thiophene-3,4-dicarboxylic acid, tetrahydropyran-4,4-dicarboxylic acid, 4-oxo-pyran-2,6-dicarboxylic acid, pyrene-2,7-dicarboxylic acid, 4,4'-dihydroxy-diphenylmethane-3, 3'-dicarboxylic acid, 4,4'-diamino-1,1'-diphenyl-3,3'-dicarboxylic acid, 4,4'-diaminodiphenyl-3,3'-dicarboxylic acid, benzidine-3,3'-dicarboxylic acid, 1,4-bis-(phenylamino)-benzene-2,5-dicarboxylic acid, 1,4-bis-(carboxymethyl)-piperazine-2,3-dicarboxylic acid, 1-(4-carboxy)-phenyl-3-(4-chloro)-phenyl-pyrazin-2-yl Zoline-4,5-dicarboxylic acid, 1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic acid, phenylindane-dicarboxylic acid, 1,3-dibenzyl-2-oxo-imidazolidine-4,5-dicarboxylic acid, 2-benzoylbenzene-1,3-dicarboxylic acid, o-hydroxy-benzophenone-dicarboxylic acid, 2,4-dichlorobenzophenone-2',5'-dicarboxylic acid, 1,4-naphthalenedicarboxylic acid Carboxylic acids, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 8-methoxy-2,3-naphthalenedicarboxylic acid, 8-nitro-2,3-naphthalenedicarboxylic acid, 8-sulfo-2,3-naphthalenedicarboxylic acid, 1,1'-dinaphthyl-8,8'-dicarboxylic acid, 1-anilinoanthraquinone-2,4'-dicarboxylic acid, polytetrahydrofuran-250-dicarboxylic acid, diimidedicarboxylic acid, 4,4'-diaminodiphenylether-diimidedicarboxylic acid, 4,4'-diaminodiphenylmethane-diimidedicarboxylic acid, 4,4'-diamino-diphenylsulfone-diimidedicarboxylic acid, 1,3-adamantanedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4''-terphenyldicarboxylic acid, 4,5,6,10-tetrahydropyrene-2,7-dicarboxylic acid, anthra dicarboxylic acids such as 1,2,3-pentanedicarboxylic acid, 2',3'-diphenyl-p-terphenyl-4,4"-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, 4(1H)-oxothiochromene-2,8-dicarboxylic acid, perylene-3,9-dicarboxylic acid, perylene dicarboxylic acid, 1-amino-4-methyl-9,10-dioxo-9,10-dihydroanthracene-2,3-dicarboxylic acid, 2,9-dichlorofluorubin-4,11-dicarboxylic acid, anthraquinone-1,5-dicarboxylic acid, and 5,6-dehydronorbornane-2,3-dicarboxylic acid; 1,2,3-propanetricarboxylic acid, 1-hydroxy-1,2,3-propanetricarboxylic acid, 2-hydroxy-1,2,3-propanetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 2-phosphono-1,2,4-butanetricarboxylic acid, and 1,2,4-benzenetricarboxylic acid; carboxylic acid, 1,3,5-benzenetricarboxylic acid, N,N',N''-tris(isophthalyl)-1,3,5-benzenetricarboxylic acid, 7-chloro-2,3,8-quinolinetricarboxylic acid, 1,3,5-tris(4'-carboxyphenyl)benzene, 4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-F]quinoline-2,7,9-tricarboxylic acid, 5-acetyl-3-amino-6-methylbenzene-1,2,4 -tricarboxylic acid, 3-amino-5-benzoyl-6-methylbenzene-1,2,4-tricarboxylic acid, aurintricarboxylic acid, 4,4',4''-(benzene-1,3,5-tolyl-tris(ethylene-2,1-diyl)tribenzenecarboxylic acid, 1,3,5-tris(4'-carboxy[1,1'-biphenyl]-4-yl)benzene, 1,3,5-tris(4'-carboxyphenyl)benzene, 1,3,5-tris Tricarboxylic acids such as (4'-carboxyphenylethynyl)benzene, 4,4',4''-triazine-2,4,6-tolyl-tribenzenecarboxylic acid, and 4,4',4''-triazine-1,3,5-tolyl-tri-4-aminobenzenecarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, 1,2,4,5-butanetetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid, and 1,2,11,12-dodecacarboxylic acid. hexanetetracarboxylic acid, 1,2,5,6-hexanetetracarboxylic acid, 1,2,7,8-octanetetracarboxylic acid, 1,4,7,10,13,16-hexaoxacyclooctadecane-2,3,11,12-tetracarboxylic acid, decane-2,4,6,8-tetracarboxylic acid, 1,2,9,10-decanetetracarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, 1,1-dioxide-perilllo[1,12-BCD] Examples include tetracarboxylic acids such as thiophene-3,4,9,10-tetracarboxylic acid, perylene tetracarboxylic acid, perylene-3,4,9,10-tetracarboxylic acid, perylene-1,12-sulfone-3,4,9,10-tetracarboxylic acid, 1,4,5,8-naphthalene tetracarboxylic acid, biphenyl-3,3',5,5',tetracarboxylic acid, benzophenone tetracarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, tetrahydrofuran tetracarboxylic acid, adamantyl tetracarboxylic acid, tetrathiafulvalene tetrabenzene carboxylic acid, and phenylporphyrin-4,4",4"",4""-tetracarboxylic acid; and hexacarboxylic acids such as 5,5',5"-(benzene-1,3,5-tolyl-tris[ethylene-2,1-diyl])triisophthalic acid, with 1,4-benzenedicarboxylic acid being preferred.

In addition, examples of the organic ligand raw material include an imidazole compound and a carboxylic acid compound, and a second organic ligand raw material may be added from the viewpoint of improving the water resistance and heat resistance of the porous zinc complex. The second organic ligand raw material is a raw material for an organic ligand that can be coordinated to at least one of the organic zinc compound of general formula (1), the imidazole compound, or the carboxylic acid compound, and one or more types may be included.
Specific examples of the second organic ligand raw material include monodentate ligands such as pyrrole, imidazole, pyridine, piperidine, quinoline, isoquinoline, isoindoline, 2-pyrroline, indole, indolizine, carbazole, phenanthridine, indoline, pyrrolidine, piperidine, quinuclidine, aziridine, and azepine; pyrazole, pyridazine, pyrimidine, pyrazine, 2-pyrazoline, pyrazolidine, 4H-quinolizine, 1H-indazole, quinazoline, cinnoline, quinoxaline, phthalazine, pteridine, acridine, phenazine, and 1,4-diazabicyclo[2.2.2. ]octane, pyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, tetramethylpyrazine, 4,4'-bipyridine, 2,2'-dimethyl-4,4'-bipyridine, 1,2-bis(4-pyridyl)ethylene, 1,4-bis(4-pyridyl)butadiyne, 1,4-bis(4-pyridyl)benzene, trans-1,2-bis(4-pyridyl)ethylene, 1,4-dicyanobenzene, 4,4'-dicyanobiphenyl, 1,2-dicyanoethylene, triethylenediamine, 2,2'-bi-1,6-naphthyridine, diazapyrene, imidazolidine, piperazine, 1,4-bis((1H-imidazol-1-yl)methyl)benzene , etc.; tridentate ligands such as 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,3-triazole, 1,2,4-triazole, 2-imidazolidinone, 1,3,5-benzenetricarboxylic acid tris[N-(4-pyridyl)amide], 1,3,5-tri(1H-imidazol-1-yl)benzene, and 1,3,5-tri(1H-pyrazol-4-yl)benzene; tetradentate ligands such as purine and 2,2'-biimidazole; and hexadentate ligands such as 3,6-di(4-pyridyl)-1,2-4,5-tetrazine and 2,4,6-tri(4-pyridyl)-1,3,5-triazine, of which 1,4-diazabicyclo[2.2.2]octane or 4,4'-bipyridyl is preferred.

The reaction solvent is preferably an aprotic solvent that does not react with the zinc complex and does not contain active hydrogen.
Specific examples of the reaction solvent include heterocyclic aromatic solvents such as pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2-propylpyridine, 3-propylpyridine, 4-propylpyridine, 4-(2-butyl)pyridine, 4-(3-pentyl)pyridine, 2,5-dimethylpyridine, 2,6-dimethylpyridine, and 3,5-dimethylpyridine; furan solvents such as tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran-3-one; tetrahydrothiophene; and 2-methyltetrahydrothiophene. thiophene-based solvents such as acetonitrile, propanenitrile, and butyronitrile; nitrile-based solvents such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-i-propyl-2-pyrrolidone, N-cyclopropyl-2-pyrrolidone, N-butyl-2-pyrrolidone, N-i-butyl-2-pyrrolidone, N-sec-butyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone, N-cyclobutyl-2-pyrrolidone, N-pentyl-2-pyrrolidone, N-1-methylbutyl-2-pyrrolidone, N-2-methylbutyl-2-pyrrolidone, N-i-pentyl-2-pyrrolidone, and N-vinyl-2-pyrrolidone; Amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N,N-diethylacetamide, N,N-dipropylformamide, N,N-di-i-propylformamide, N,N-dibutylformamide, N,N-di-i-butylformamide, N,N-di-sec-butylformamide, and N,N-di-tert-butylformamide; carbamide solvents such as tetramethylurea, N,N'-dimethylethyleneurea, and N,N'-dimethylpropyleneurea; acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, cyclopentanone, ethyl propyl ketone, cyclohexanone, methyl pentyl ketone; ketone solvents such as methyl cyclopentyl ketone, propyl butyl ketone, dipropyl ketone, dibutyl ketone, etc.; sulfoxide solvents such as dimethyl sulfoxide, ethyl acetate, propyl acetate, i-propyl acetate, butyl acetate, i-butyl acetate, sec-butyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, i-propyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, i-propyl butyrate, methyl isobutyrate, ethyl isobutyrate, propyl isobutyrate, i-propyl isobutyrate, methyl pivalate, methyl 2-methylbutyrate, methyl valerate, methyl isovalerate, methyl methoxyacetate, ethyl methoxyacetate methyl dimethoxyacetate, 2-ethoxyethyl acetate, methyl methoxypropionate, methyl methoxybutyrate, methyl methoxyisobutyrate, methyl hexanoate, methyl heptanoate, methyl octanoate, methyl nonanoate, methyl decanoate, methyl dodecanoate, ethyl tetrahydrofuran-2-acetate, tetrahydrofurfuryl propionate, methyl 1-methylcyclopropanecarboxylate, methyl benzoate, ethyl benzoate, n-propyl benzoate, i-propyl benzoate, n-butyl benzoate, sec-butyl benzoate, tert-butyl benzoate, n-ethyl benzoate, n-hexyl benzoate, ethylene carbonate, propylene carbonate, butylene carbonate, ethyl methyl carbonate ester solvents such as propyl methyl carbonate, propyl methyl carbonate, i-propyl methyl carbonate, ethyl propyl carbonate, ethyl i-propyl carbonate, propyl i-propyl carbonate, butyl methyl carbonate, butyl ethyl carbonate, butyl propyl carbonate, butyl i-propyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, di-i-propyl carbonate, dibutyl carbonate, di-i-butyl carbonate, di-sec-butyl carbonate, di-tert-butyl carbonate, dipentyl carbonate, γ-butyrolactone, γ-valerolactone, γ-hexanolactone, γ-heptanolactone, γ-octanolactone, γ-nonanolactone, γ-decanolactone, γ-dodecanolactone, and α-heptyl-γ-butyrolactone; ethylene Glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol di-i-propyl ether, ethylene glycol dibutyl ether, ethylene glycol diacetate, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol 1-monomethyl ether-2-acetate, trimethoxyethane, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol propyl methyl ether, diethylene glycol -i-propyl methyl ether, diethylene glycol butyl methyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol di-i-propyl ether, diethylene glycol dibutyl ether, diethylene glycol diacetate, triethylene glycol dimethyl ether, triethylene glycol ethyl methyl ether, triethylene glycol propyl methyl ether, triethylene glycol -i-propyl methyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, 12-crown 4-ether, 15-crown 5-ether, 1,4-dioxane, 1,4-epoxycyclohexane and other ether solvents can be exemplified.
Furthermore, the aprotic solvent is not limited to one type of solvent, and two or more types of solvents may be mixed and used. From the viewpoint of easily controlling the reaction temperature between the zinc compound and the ligand, heterocyclic aromatic solvents such as pyridine and sulfoxide solvents such as dimethyl sulfoxide are preferred. Furthermore, from the viewpoint of easily forming a porous zinc complex, lactam solvents such as N-methyl-2-pyrrolidone and amide solvents such as N,N-dimethylformamide are preferred. Pyridine, dimethyl sulfoxide, and N,N-dimethylformamide are more preferred.

Next, the method for producing the porous zinc complex of the present invention will be described in detail.
The production method of the present invention comprises a step of reacting an organic zinc compound with an organic ligand raw material (hereinafter referred to as the reaction step) and a step of extracting the resulting porous zinc complex (hereinafter referred to as the purification step).

The reaction process includes a first step in which the organozinc compound is solvated with a reaction solvent, and a second step in which the organozinc compound is reacted with an organic ligand raw material. This reaction is carried out entirely in an inert atmosphere. There are no particular restrictions on the inert gas used, as long as it does not react with the organozinc compound; nitrogen or argon is preferred. Nitrogen or argon may be used alone or mixed in any ratio. It is preferable to keep the water content of the reaction solvent used as low as possible to suppress by-production of oxides and other such compounds. Specifically, it is 50 ppm or less, more preferably 20 ppm or less, and even more preferably 10 ppm or less.

In the first step, an organozinc compound is added to a solvent with a controlled water content and aged to prepare a solution of the organozinc compound (hereinafter referred to as an organozinc compound solution).
The stirring and mixing conditions in the first step are preferably stirring and mixing from the viewpoint of preparing a uniform organic zinc compound solution.
The reaction concentration in the first step is not particularly limited, and specific examples thereof include 0.001 mol/L to 10 mol/L (1 mol/L is the concentration of an organozinc compound solution prepared by dissolving 1 mol of an organozinc compound in 1 L of a solvent). From the viewpoint of efficiently removing the heat of reaction between the organozinc compound and the organic ligand raw material in the second step, the reaction concentration is more preferably 0.005 mol/L to 1 mol/L, and particularly preferably 0.01 mol/L to 0.1 mol/L.

The temperature at which the organozinc compound is added in the first step is not limited as long as it allows the reaction temperature to be controlled, and specifically includes a temperature of 30° C. or lower. However, in order to control the temperature within ±2° C., a temperature of −20° C. to 20° C. is more preferable, and a temperature of −15° C. to 0° C. is particularly preferable. From the viewpoint of controlling the reaction temperature, the organozinc compound is preferably added dropwise when the organozinc compound is a liquid, or added in portions when the organozinc compound is a solid.
The ripening temperature in the first step may be 30°C or lower, more preferably -20°C to 20°C, and particularly preferably -15°C to 0°C. The ripening temperature may be changed from the temperature at which the organozinc compound is added. In this case, in order to suppress side reactions, it is preferable to control the temperature change per unit time from the temperature at which the organozinc compound is added to the ripening temperature (hereinafter referred to as the temperature change rate). Specifically, the temperature change rate is preferably 0.01°C/min to 5°C/min, more preferably 0.05°C/min to 1°C/min, and particularly preferably 0.1°C/min to 0.5°C/min.
The aging time in the first step is not particularly limited, but specifically, it is preferably 24 hours or less, and more preferably 1 hour to 12 hours.

The second step is a step of reacting an organic zinc compound with an organic ligand raw material and aging the mixture to produce the porous zinc complex of the present invention.
The molar ratio of the organic zinc compound to the organic ligand raw material is not particularly limited. When the organic ligand raw material is an imidazole compound, 2 mol of the imidazole compound may be added per 1 mol of the organic zinc compound. From the viewpoint of reducing the amount of unreacted organic zinc compound and imidazole compound, the molar ratio of the organic zinc compound to the imidazole compound is preferably 1:1.0 to 1:5.0, more preferably 1:1.4 to 1:4.0, and particularly preferably 1:1.8 to 1:3.0. When the organic ligand raw material is a carboxylic acid compound, the amount of the carboxylic acid compound that may be added per 1 mol of the organic zinc compound varies depending on the number of carboxy groups in the molecule. For example, when the carboxylic acid compound is a dicarboxylic acid, 0.75 mol of dicarboxylic acid may be added per mol of the organozinc compound, and the molar ratio of the organozinc compound to the dicarboxylic acid is preferably 1:0.30 to 1:2.0, more preferably 1:0.45 to 1:1.5, and particularly preferably 1:0.60 to 1:1.0, from the viewpoint of reducing the amount of unreacted organozinc compound and dicarboxylic acid compound. When the carboxylic acid compound is a tricarboxylic acid, 0.50 mol of tricarboxylic acid may be added per mol of the organozinc compound, and the molar ratio of the organozinc compound to the tricarboxylic acid is preferably 1:0.20 to 1:1.0, more preferably 1:0.25 to 1:0.85, and particularly preferably 1:0.30 to 1:0.70.
The stirring and mixing conditions in the second step may be such that the reaction is carried out in a stationary state or by stirring and mixing. Alternatively, the reaction may be carried out by a method in which the particles are pulverized by applying compression or shear force to the particles, as in a ball mill, or by generating bubbles locally on the particle surface by using ultrasonic waves or microwaves.
The reaction concentration in the second step is not particularly limited, and specifically includes 1 mol/L or less (1 mol/L is a reaction solution in which 1 mol of an organic zinc compound is dissolved in 1 L of a reaction solvent). From the viewpoint of high purity of the produced porous zinc complex, the concentration is more preferably 0.005 mol/L to 1 mol/L, and particularly preferably 0.01 mol/L to 0.1 mol/L.

In the production method of the second step, the organic ligand raw material or a solution of the organic ligand raw material may be added to the organic zinc compound solution, or the organic ligand raw material or a solution of the organic ligand raw material may be added to the organic ligand raw material.
The temperature at which the organic ligand raw material, the solution of the organic ligand raw material, or the organozinc compound solution is added in the second step is preferably a temperature at which the reaction temperature can be controlled, and specifically, 100° C. or lower. In order to control the temperature within a control range of ±2° C., a temperature of −20° C. to 50° C. is more preferable, and a temperature of −15° C. to 20° C. is particularly preferable. From the viewpoint of controlling the reaction temperature, the method of adding the organic ligand raw material, the solution of the organic ligand raw material, or the organozinc compound solution is preferably a dropwise addition method in the case of a liquid organic ligand raw material, a solution of the organic ligand raw material, or an organozinc compound solution, and a divided addition method in the case of a solid organic ligand raw material or organozinc compound.
The ripening temperature in the second step may be −20 to 200° C., more preferably 0 to 150° C., and particularly preferably 20 to 120° C. The ripening temperature may be changed from the temperature at which the organic ligand raw material, the organic ligand raw material solution, or the organic zinc compound solution is added. Here, it is preferable to control the rate of temperature change from the temperature at which the organic ligand raw material, the organic ligand raw material solution, or the organic zinc compound solution is added to the ripening temperature. Specifically, the rate of temperature change is preferably 10° C./min or less, more preferably 0.01 to 5° C./min, and particularly preferably 0.1 to 3° C./min.
The aging temperature may be appropriately changed during the aging in the second step. In this case, it is preferable to control the temperature change rate. Specifically, the temperature change rate is preferably 10°C/min or less, more preferably 0.01°C/min to 5°C/min, and particularly preferably 0.1°C/min to 3°C/min.
The reaction pressure in the second step may be 0.1 MPa to 10 MPa, more preferably 0.1 MPa to 2 MPa, and particularly preferably 0.1 MPa to 1 MPa.
The aging time in the second step is not particularly limited, but specifically, it is 240 hours or less, more preferably 1 hour to 48 hours, and most preferably 1 hour to 24 hours.

The purification step comprises a solid-liquid separation step, a washing step, and a drying step, and the porous zinc complex of the present invention can be obtained.
The solid-liquid separation step is a step of separating the solid phase containing the porous zinc complex from the reaction solution in which the unreacted ligand and the aprotic solvent are dissolved. There are no particular limitations on the method of solid-liquid separation, and examples include centrifugation, settling, concentration, and filtration. An appropriate method can be selected taking into consideration the sedimentation property of the porous zinc complex, the boiling point of the reaction solvent, etc.

The washing step is a step of removing from the porous zinc complex the reaction solution that cannot be extracted in a single solid-liquid separation step. That is, the washing step is an operation of washing the porous zinc complex by solid-liquid separation using a solvent (hereinafter referred to as washing solvent) that is uniformly mixed with the reaction solution and in which the porous zinc complex does not dissolve. In the catalytic reaction of the porous zinc complex, impurities such as components of the reaction solution interfere with the reaction, so it is preferable to repeat the washing step. For example, when a crude slurry containing 1 g of porous zinc complex is washed with 5 g of washing solvent in one wash, the specific number of washes can be 5 or more, but 5 to 6 times is preferred.
The washing solvent used in the washing step may be not only one type of solvent, but also two or more types of solvents. The washing solvent is preferably the aprotic solvent used in the reaction step, or a solvent not containing oxygen in the molecule. Examples of the aprotic solvent used in the former reaction step include the solvents described in the reaction step, and pyridine, dimethyl sulfoxide, and N,N-dimethylformamide are more preferred. Specific examples of the latter washing solvent not containing oxygen in the molecule include chloroform, dichloromethane, chloromethane, benzene, toluene, xylene, mesitylene, styrene, cumene, pentane, hexane, heptane, ethylbenzene, chlorobenzene, and bromobenzene. From the viewpoint of solubility of the reaction solution, chloroform, dichloromethane, and toluene are more preferred.

The drying step is a step in which the washing solvent is dried. There are no particular restrictions on the drying temperature as long as it does not decompose the porous zinc complex, but specific examples include 20°C to 400°C, with 20°C to 100°C being preferred and 20°C to 40°C being particularly preferred. The drying pressure may be a method in which the washing solvent is distilled off under reduced pressure, or a method in which the washing solvent is distilled off using pressurized nitrogen gas or argon gas. There are no particular restrictions on the drying pressure, but specific examples include a reduced pressure of 1 kPa or less. From the perspective of efficiently distilling off the washing solvent, a reduced pressure of 0.1 kPa or less is more preferred, and a reduced pressure of 0.01 kPa or less is particularly preferred. There are no particular restrictions on the drying time, but specific examples include 1 hour to 120 hours, with 5 hours to 60 hours being more preferred and 10 hours to 30 hours being particularly preferred.

Next, a method for measuring the surface hydroxyl groups and adsorbed water contained in the porous zinc complex of the present invention will be described.
The oxygen concentration derived from the hydroxyl groups and adsorbed water remaining on the surface of the porous zinc complex of the present invention is extremely low. This oxygen concentration can generally be measured by X-ray photoelectron spectroscopy (hereinafter referred to as "XPS"), and the ratio of elements constituting the surface of the porous zinc complex can be obtained from the intensity of photoelectrons emitted by irradiating the solid surface with X-rays.
The element ratio can be calculated relatively by the relative sensitivity factor method using the sensitivity coefficient specific to the device from the relationship between the binding energy value of the electron and atomic nucleus, which depends on the type of atom and its bonding state, and the intensity of emitted photoelectrons. The oxygen atom concentration of the porous zinc complex of the present invention measured by XPS is 2.5 atm% or less, more preferably 1 atm% or less, and particularly preferably 0.1 atm% or less.

Next, the physical properties of the porous zinc complex of the present invention and methods for measuring them will be described.
The BET specific surface area of the porous zinc complex of the present invention is 600 m ² /g or more. The BET specific surface area can be measured by nitrogen adsorption. For example, a porous zinc complex from which organic matter physically adsorbed at 200°C has been removed by drying under reduced pressure is cooled to 77 K (absolute temperature unit, equivalent to approximately -196°C) with liquefied nitrogen, and nitrogen gas is gradually introduced from a vacuum state to measure an adsorption isotherm relating the equilibrium pressure of nitrogen gas and the amount of adsorption. The BET specific surface area can be obtained from this adsorption isotherm.
The thermal decomposition temperature of the porous zinc complex of the present invention is 350°C or higher and can be determined by thermogravimetric analysis (TG analysis). The thermal decomposition temperature can be read from the temperature corresponding to the intersection of the tangent to the inflection point of the weight loss curve obtained by TG analysis and the extension of the baseline.
The present invention makes it possible to obtain nanoparticle porous zinc complexes having a shape close to spherical. The diameter of the nanoparticles is preferably 1 nm to 50 nm, more preferably 5 nm to 30 nm, and particularly preferably 10 nm to 20 nm.

Finally, the uses of the porous zinc complex of the present invention will be described.
The porous zinc complex of the present invention can be used as a reaction catalyst as it is, or as a supported catalyst in which it is fixed to a metal or a metal complex.

Reactions in which the porous zinc complex of the present invention can be used as a catalyst include those reported for porous zinc complexes produced using inorganic salts such as metal nitrate hydrates as raw materials. Examples of reactions that can be carried out using the porous zinc complex as a solid basic catalyst include formylation, carbonylation, Knoevenagel condensation, aldol reaction, Michael addition reaction, carbonyl insertion, esterification, olefin production (Wadsworth-Emmons reaction), hydrogenation of olefins or alkynes, and olefin epoxidation.

When the porous zinc complex of the present invention is used as a catalyst, it can be used in the form of either a solid powder or a slurry.
The reaction concentration when the porous zinc complex of the present invention is used as a catalyst is not particularly limited, but is preferably 0.10 mol/L or less (the concentration when 0.1 mol of the porous zinc complex is dispersed in 1 L of the reaction solvent). As the catalyst concentration increases, the product concentration increases and the viscosity of the reaction solution increases, so from the viewpoint of stirring efficiency, the concentration is more preferably 0.05 mol/L or less, and particularly preferably 0.01 mol/L or less.
The reaction time when the porous zinc complex of the present invention is used as a catalyst is not particularly limited, but may be 120 hours or less, more preferably 48 hours or less, and particularly preferably 24 hours or less.
The reaction pressure (in absolute pressure units) when the porous zinc complex of the present invention is used as a catalyst is not particularly limited, but may be 0.1 MPa to 10 MPa, more preferably 0.1 MPa to 2 MPa, and particularly preferably 0.1 MPa to 1 MPa.
The reaction temperature when the porous zinc complex of the present invention is used as a catalyst is not particularly limited as long as it is below the decomposition temperature of the porous zinc complex, but may be 400°C or below, more preferably 200°C or below, and particularly preferably 100°C or below.

After using the porous zinc complex of the present invention as a reaction catalyst, the catalyst can be separated and reused. Methods for separating the catalyst from the reaction product include, but are not limited to, centrifugation, settling, concentration, and filtration. After solid-liquid separation, the porous zinc complex can be reused by washing it with a washing liquid. The washing liquid used here is preferably a hydrophobic solvent, such as chloroform, dichloromethane, chloromethane, benzene, toluene, xylene, mesitylene, styrene, cumene, pentane, hexane, heptane, ethylbenzene, chlorobenzene, and bromobenzene. Toluene and hexane are preferred from the perspective of versatility.

Furthermore, the porous zinc complex of the present invention can be used for gas adsorption, separation, and storage. Gases that can be adsorbed include hydrogen, nitrogen, oxygen, argon, nitric oxide, nitrogen dioxide, carbon monoxide, carbon dioxide, hydrogen sulfide, sulfur dioxide, saturated hydrocarbons such as methane, ethane, propane, and butane, and unsaturated hydrocarbons such as ethylene, acetylene, propylene, methylacetylene, 1-butene, cis-2-butene, trans-2-butene, and 2-methylpropene.

The present invention will be explained in detail below using examples, but the present invention is not limited to these examples.

Reagents included diethyl zinc (manufactured by Tosoh Finechem Co., Ltd.), zinc nitrate hexahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 2-methylimidazole (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), methanol (manufactured by Kishida Chemical Co., Ltd.), pyridine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., dehydrated grade, water concentration 10 ppm or less), toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., dehydrated grade, water concentration 10 ppm or less), and hexane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., dehydrated grade, water concentration 10 ppm or less). Terephthalic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), N,N-dimethylformamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., dehydrated grade, water concentration 10 ppm or less), dichloromethane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., dehydrated grade, water concentration 10 ppm or less), diphenylamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), formic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), trifluoroethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), hexamethylbenzene (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.02 mol/L Ethylenediaminetetraacetic acid (hereinafter referred to as EDTA) solution (Kishida Chemical Co., Ltd.), 0.02 mol/L zinc sulfate aqueous solution (Kishida Chemical Co., Ltd.), 97% sulfuric acid (Kishida Chemical Co., Ltd.), anhydrous sodium acetate (Kishida Chemical Co., Ltd.), anhydrous ammonium acetate (Kishida Chemical Co., Ltd.), dithizone (Fujifilm Wako Pure Chemical Industries, Ltd.), 2-propanol (Fujifilm Wako Pure Chemical Industries, Ltd.), and acetone (Fujifilm Wako Pure Chemical Industries, Ltd.) were used as they were without purification.
Deuterated chloroform (CDCl ₃ ) (containing 1 wt % tetramethylsilane, manufactured by the French Atomic Energy Commission) was left to stand for at least one day under a nitrogen atmosphere with 10 g of A3 Zeolum (manufactured by Tosoh Corporation, 4-8 mesh, beads) as a desiccant. The A3 Zeolum was dried under reduced pressure for 12 hours in a desiccator at 120°C before use.

<Measurement of Zn concentration in porous zinc complex, chelate titration>
The porous zinc complex was hydrolyzed, and the chelating agent EDTA was added, and the weight percent concentration of Zn contained in the porous zinc complex was measured by back titration with an aqueous _ZnSO4 solution. The measurement procedure is shown below.
1) Preparation of hydrolyzed solution of porous zinc complex 100 mL of 1.0 mol/L aqueous sulfuric acid solution, 50 mL of hexane, and approximately 50 to 100 mg of porous zinc complex were mixed, immersed in a thermostatic bath at 65°C, and stirred for 30 minutes to hydrolyze the porous zinc complex. The aqueous phase after hydrolysis (hereinafter referred to as the hydrolyzed solution) was collected by liquid separation.
2) Preparation of titrant solution 10 mL of the hydrolysis solution, approximately 7 mL of 0.02 mol/L EDTA solution, and 10 mL of sodium acetate buffer solution (pH 5.0) were placed in a glass container and immersed in a thermostatic bath at 39°C for 20 minutes. After removing the glass container from the thermostatic bath, 10 mL of ammonium acetate buffer solution (pH 5.0), 70 mL of 2-propanol, and a few drops of dithizone indicator were added.
3) Titration A 0.02 mol/L _ZnSO4 solution was prepared in a burette and titrated into the titrant. When approximately 6-7 mL of the 0.02 mol/L zinc sulfate solution was added dropwise, the color of the titrant changed from blue-green to magenta, confirming the formation of a chelate complex in the titrant, and the titration was then completed.
4) Calculation of Zn concentration in porous zinc complex The Zn concentration was calculated using the following formula.

<XPS measurement and calculation of elemental composition>
The equipment, measurement conditions, and calculation method for element concentrations used to analyze the element composition contained in the surface of the sample are as follows:
・Device: JEOL Ltd. (manufactured) JPS-9010MX
・X-ray source: MgKα
・Measurement angle: 45°
・Number of accumulations: 8
Observation energy: O1s orbital (505-545 eV), C1s orbital (270-295 eV), N1s orbital (375-415 eV), Zn2p orbital (995-1,035 eV)
・Element concentration calculation method:

<Measurement of specific surface area>
The specific surface area of the sample was determined by measuring an isotherm by nitrogen adsorption and analyzing it by the BET method.
・Device: BELSORP MINI II (manufactured by Japan Bell Co., Ltd.)
Analysis software: BELMaster version 5.3.3.4
Pretreatment: 200°C for 6 hours
Adsorption gas: nitrogen Adsorption/desorption temperature: -196°C
Equilibrium relative pressure used to calculate the specific surface area: 0.0002<p/p ₀ <0.16

<Measurement of thermal decomposition temperature>
The thermal decomposition temperature of the sample was measured by TG under the following conditions:
・Device: DTG-60H (Shimadzu Corporation)
- Temperature range: 25℃ to 700℃
Temperature increase rate: 5°C/min
Gas atmosphere: air

<Observation of particle size and shape>
The particle size and shape of the sample were observed by TEM under the following conditions:
・Device: JEM-2010 (manufactured by JEOL Ltd.)
Acceleration voltage: 200 kV
<Observation of particle size and shape>
The particle size and particle shape of the sample were observed using an FE-SEM under the following conditions:
Apparatus: S-4800 (Hitachi High-Technologies Corporation)
Acceleration voltage: 1 kV

<Evaluation of catalytic activity of the porous zinc complex of the present invention>
The catalytic activity (conversion rate and yield per unit time) of the porous zinc complex of the present invention and that of the comparative example were evaluated in the following chemical reaction (chemical reaction formula 4).

The conversion rate of the raw materials and the yield of the product were determined by sampling the reaction crude liquid at regular intervals and measuring ¹ H-NMR. The measuring device and conditions were as follows:
Device: Delta v5.0.3 500MHz (manufactured by JEOL Ltd.)
Measurement conditions: measurement nucleus ¹ H, cumulative 16 times, relaxation time 15 sec, measurement temperature 21°C
Solvent: CDCl ₃ (containing 1 wt % tetramethylsilane)
Number of measurements: 5 times within 50 hours of aging Measurement method for raw material conversion rate and product yield:
The internal standard (tetramethylbenzene) was determined from the peak area ratio of the reference peak and the product using the following formula:
(1) Amount of raw material and product after X hours (mol)
(2) Conversion rate of raw material and yield of product after X hours
¹ H-NMR (CDCl ₃ ) of raw material (N,N-diphenylamine):
δ6.94 (2H, dd, 7Hz), δ7.07 (1H, s), δ7.09 (4H, dd, 14Hz), δ7.27 (4H, dd, 8Hz)
¹ H-NMR (CDCl ₃ ) of the product (N,N-diphenylformamide):
δ7.17 (2H, d, 8.5Hz), δ7.34 (1H, t, 8.0Hz), δ7.29 (1H, t, 8.8Hz), δ7.29 (1H, t, 8.8Hz), δ7.27 (1H, t, 8.3Hz), δ7.42 (4H, d, 9.0Hz), δ8.64 (1H, s)
¹ H-NMR (CDCl ₃ ) of internal standard (hexamethylbenzene):
δ2.24 (18H, s)

Example 1
<Synthesis> Synthesis of Porous Zinc Complex (2-Methylimidazole Zinc Salt) in a Hydrophobic Atmosphere (Reaction Step 1) Preparation of 1.0 mol/L Diethylzinc Pyridine Solution 246 mL of pyridine was added to a glass flask (volume: 500 mL) under a slightly pressurized nitrogen atmosphere, and the liquid temperature in the flask was cooled to -10°C while stirring. Once the liquid temperature stabilized within the range of -11°C to -9°C, the dropwise addition of 25 mL of diethylzinc was initiated, and the dropwise addition rate was adjusted so that the liquid temperature in the flask was maintained within the temperature range of -11°C to -9°C. After the dropwise addition, the mixture was aged at -10°C for 1 hour and then heated to 20°C at a constant rate over 100 minutes. After the liquid temperature in the flask reached 20°C, the mixture was aged for 6 hours at a temperature of 20°C. 270 g of a transparent yellow solution was recovered.

(Reaction Step 2) Synthesis of Porous Zinc Complex (2-Methylimidazole Zinc Salt) 420 mL of pyridine was added to a glass flask (volume 1 L) under a slightly pressurized nitrogen atmosphere, and 16.5 mL of a 0.9 mol/L pyridine solution of diethylzinc (14.7 mmol of diethylzinc) was added. The temperature inside the flask was cooled to -10°C while stirring. Once the liquid temperature stabilized within the range of -11°C to -9°C, 108.6 g of a previously prepared 2.5 wt% pyridine solution of 2-methylimidazole (32.9 mmol of 2-methylimidazole) was added dropwise via a dropping funnel over 300 minutes, adjusting the rate so that the liquid temperature remained within the range of -10°C to -6°C. After the dropwise addition, the dropping funnel was washed with 30 mL of pyridine, and the washings were added dropwise to the flask. After the washings were added dropwise to the flask, the mixture was aged at -10°C for 1 hour and then heated to 20°C at a constant rate over approximately 100 minutes (heating rate: 0.31°C/min). After the liquid temperature in the flask reached 20°C, aging was initiated while maintaining the liquid temperature at 20°C. After 1.5 hours of aging, the liquid changed to a colorless and transparent state, and after 4 hours of reaction, it became cloudy and began to precipitate. After 16 hours, the conversion rate of diethylzinc was measured from the supernatant liquid in the flask by ^1H -NMR and was found to be 95%. After 19 hours, a similar measurement was performed and the conversion was still 95%, so 561 g of a cloudy white slurry was recovered.

(purification process)
To extract the porous zinc complex, the recovered cloudy slurry was separated into a white solid layer and a colorless, transparent supernatant layer by centrifugation (Kokusan Co., Ltd., H-103N, rotation speed 3,400 rpm, rotation time 30 min), and the supernatant layer was removed. Subsequently, to remove any remaining unreacted ligand, 1.4 L of pyridine was added to the white solid layer, and the mixture was washed three times by centrifugation and removal of the supernatant layer. Next, to remove pyridine, 1.4 L of toluene was added to the white solid layer, and the mixture was washed three times in the same manner. Furthermore, to remove toluene, 1.4 L of hexane was added to the white solid layer, and the mixture was washed three times in the same manner. Finally, the glass container containing the white solid layer was placed in a desiccator at 40°C and dried under reduced pressure for 24 hours, and 3.7 g of white solid was recovered.

<Yield>
As a result of the chelate titration described above (porous zinc complex 88.8 mg, EDTA amount 0.151 mmol, ZnSO _0.126 mmol), the Zn concentration of the porous zinc complex of this example was 24.0 wt %. The Zn yield of this example, calculated from this Zn concentration, was 93%.

<Specific surface area>
The BET specific surface area of the porous zinc complex of this example was 805 ^{m 2} /g, and the pore volume was 1.2 mL/g. The nitrogen adsorption isotherm of the porous zinc complex of this example is shown in Figure 1. In Figure 1, the solid line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during adsorption in Example 1, and the dashed line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during desorption in Example 1.

<Thermal decomposition temperature>
The TG curve of the porous zinc complex of this example is shown in Figure 2-1. In Figure 2-1, in the curve showing the weight loss with increasing temperature, the approximate temperature at which the porous zinc complex of Example 1 is estimated to have thermally decomposed, i.e., the point where the extrapolated line on the low temperature side intersects with the extrapolated line on the high temperature side (shown by a black circle), was approximately 361°C.

<Particle size>
It was confirmed that the porous zinc complex of this example was composed of aggregates of nanoparticles of 10 to 30 nm in size and nearly spherical in shape. The TEM image is shown in Figure 3-1.

Comparative Example 1 Synthesis of porous zinc complex having ZIF-8 crystal structure in a hydrophilic atmosphere The complex was synthesized according to the method described in Non-Patent Document 3.

<Synthesis>
3.3 g (39.6 mmol) of 2-methylimidazole and 100 mL of methanol were added to a glass bottle (volume 250 mL) and stirred to dissolve the 2-methylimidazole. 79.4 g of a 0.05 mol/L solution of zinc nitrate hexahydrate in methanol (zinc nitrate 5.0 mmol) was added, and after stirring at room temperature for 24 hours, 160.0 g of a milky white colloidal dispersion was recovered. The solution was separated into a white solid layer and a colorless, transparent supernatant layer by centrifugation (Kokusan Co., Ltd., H-103N, rotation speed 3,400 rpm, rotation time 30 min), and the supernatant layer was removed. Next, 160 mL of methanol was added, and the mixture was washed three times by centrifugation (Kokusan Co., Ltd., H-103N, rotation speed 3,400 rpm, rotation time 75 min) and the supernatant layer was removed. After washing, the remaining white solid layer was placed in a desiccator at 40° C. and dried under reduced pressure for 24 hours, and 0.49 g of a white solid was recovered.

<Yield>
As a result of the chelate titration described above (porous zinc complex 48.2 mg, EDTA 0.139 mmol, ZnSO _0.124 mmol), the Zn concentration of the porous zinc complex of this comparative example was 26.1 wt %. The Zn yield of this example, calculated from this Zn concentration, was 39%.

<Activation treatment-1>
To inactivate the surface hydroxyl groups contained in the porous zinc complex of Comparative Example 1 and remove adsorbed water, 111 mg of the porous zinc complex was placed in a desiccator heated to 100°C and dried under reduced pressure for 12 hours (weight after drying: 89 mg).

<Activation Treatment-2>
To inactivate the surface hydroxyl groups contained in the porous zinc complex of Comparative Example 1 and remove adsorbed water, 27.7 mg of the porous zinc complex was placed in a desiccator heated to 200°C and dried under reduced pressure for 6 hours (weight after drying: 26.4 mg).

<Specific surface area>
The BET specific surface area of the porous zinc complex of this comparative example was 1,779 ^{m 2} /g, and the pore volume was 1.2 mL/g. The maximum nitrogen adsorption capacity of the porous zinc complex of this comparative example was 70 mL/g. The nitrogen adsorption isotherm of the porous zinc complex of this comparative example is shown in Figure 1. In Figure 1, the solid line with gray triangles (▲) shows the relationship between the relative pressure and the N ₂ adsorption capacity during adsorption in Comparative Example 1, and the dashed line with gray triangles (▲) shows the relationship between the relative pressure and the N ₂ adsorption capacity during desorption in Comparative Example 1.

<Thermal decomposition temperature>
Figure 2-2 shows the TG curve of the porous zinc complex of this comparative example that was subjected to activation treatment-1. In Figure 2-1, in the curve showing the weight loss with increasing temperature, the approximate temperature at which the porous zinc complex of Comparative Example 1 is estimated to have thermally decomposed, i.e., the point where the extrapolated line on the low temperature side intersects with the extrapolated line on the high temperature side (shown by a black circle), was approximately 400°C.

<Particle size>
The porous zinc complex of this comparative example was confirmed to have a polyhedral particle shape of about 20 to 50 nm. The TEM image is shown in Figure 3-2.

<Surface elemental composition>
The XPS spectral patterns of oxygen, carbon, nitrogen, and zinc of the porous zinc complex of this Example 1 and the porous zinc complex of Comparative Example 1 that had been subjected to activation treatment (activation treatment-1: 100°C, 12 hours, activation treatment-2: 200°C, 6 hours) are shown in Figures 4-1, 4-2, 4-3, and 4-4, respectively.
As mentioned above, Comparative Example 1 shows the results of a sample that was subjected to reduced pressure drying under heating and baking at a constant temperature (hereinafter, simply referred to as "activation treatment") in order to remove surface hydroxyl groups and adsorbed water. The activation treatment was evaluated under two conditions, differing in heating temperature and heating time. In Figures 4-1 to 4-4, the results of Example 1 are shown by a bold solid line. Furthermore, for Comparative Example 1, activation treatment-1, which was performed under conditions of 100°C for 12 hours, is shown by a thin solid line, and activation treatment-2, which was performed under conditions of 200°C for 6 hours, is shown by a dashed line.

The atomic concentrations of the constituent elements calculated relatively from the emitted photoelectron intensity using the relative sensitivity factor method are shown in Table 1.

These results confirm that the porous zinc complex of Example 1 has a lower surface oxygen composition and a higher surface nitrogen composition than the porous zinc complex of Comparative Example 1. This suggests that the surface chemical structure of the porous zinc complex of Example 1 has a higher composition of zinc-imidazolyl groups represented by general formula (2-1) and fewer surface hydroxyl groups and adsorbed water represented by general formula (2-2) than the porous zinc complex of Comparative Example 1.

Example 2
<Evaluation of catalytic activity of Example 1>
135 mg of the porous zinc complex of Example 1, 48 mg of hexamethylbenzene, and 33 mL of trifluoroethanol were placed in a glass flask (volume 200 mL) under a slightly pressurized nitrogen atmosphere. The liquid temperature in the flask was raised to 65°C while stirring. One hour after the start of stirring, 1.53 g of N,N-diphenylamine and 1.1 mL of formic acid were added, and aging was initiated while maintaining the liquid temperature at 65°C. The time-dependent changes in the conversion rate of the raw material N,N-diphenylamine and the yield of the product N,N-diphenylformamide are shown in Figure 5. The initial activity after 5 hours of aging was 1.1 mol/Zn-mol.hr. In Figure 5, black circles (●) indicate the yield in Example 2, and white circles (○) indicate the conversion rate in Example 2.

Comparative Example 2
<Evaluation of catalytic activity in Comparative Example 1>
89 mg of the porous zinc complex of Comparative Example 1 that had been subjected to Activation Treatment-1, 42 mg of hexamethylbenzene, and 29 mL of trifluoroethanol were placed in a glass flask (volume 200 mL) under a slightly pressurized nitrogen atmosphere. The liquid temperature in the flask was raised to 65°C while stirring. One hour after the start of stirring, 1.27 g of N,N-diphenylamine and 1.0 mL of formic acid were added, and aging was initiated while maintaining the liquid temperature at 65°C. Figure 5 shows the time-dependent changes in the conversion rate of the raw material N,N-diphenylamine and the yield of the product N,N-diphenylformamide. The initial activity after 5 hours of aging was 0.35 mol/Zn-mol.hr. In Figure 5, black squares (■) indicate the yield in Comparative Example 2, and white squares (□) indicate the conversion rate in Comparative Example 2.

Example 3
<Synthesis>
(Reaction Step 1) Preparation of 1.0 mol/L Diethylzinc Dimethyl Sulfoxide Solution 243 mL of dimethyl sulfoxide was added to a glass flask (volume 500 mL) under a slightly pressurized nitrogen atmosphere, and the liquid temperature in the flask was cooled to -10 ° C while stirring. Once the liquid temperature stabilized within the range of -11 to -9 ° C, the dropwise addition of 25 mL of diethylzinc was initiated, and the dropwise addition rate was adjusted so that the liquid temperature in the flask was maintained within the temperature range of -11 to -9 ° C. After the dropwise addition over 33 minutes, the mixture was aged at -10 ° C for 1 hour and then heated to 20 ° C at a constant rate over 100 minutes. After the liquid temperature in the flask reached 20 ° C, the mixture was aged for 6 hours at a liquid temperature of 20 ° C. 299 g of a transparent yellow solution was recovered.

(Reaction Step 2) Synthesis of Porous Zinc Complex (2-Methylimidazole Zinc Salt)
In a glove box under a slightly pressurized nitrogen atmosphere, zirconia balls (10 mm diameter), 0.82 g (10.0 mmol) of 2-methylimidazole, and 2.0 mL of a 1.0 mol/L diethylzinc dimethyl sulfoxide solution (2.0 mmol of diethylzinc) were placed in a ball mill container and sealed. The sealed container was set to a planetary ball mill (P-6 manufactured by Fritsch), and kneading treatment was carried out at a rotation speed of 150 rpm for 30 minutes.

(purification process)
After the kneading treatment, the cloudy slurry was recovered and separated into a white solid layer and a colorless, transparent supernatant layer by centrifugation (Kokusan Co., Ltd., H-103N, rotation speed 3,400 rpm, rotation time 30 min), and the supernatant layer was removed. Subsequently, to remove any remaining unreacted ligand, 190 mL of dimethyl sulfoxide was added to the white solid layer, and the mixture was washed four times by centrifugation and removal of the supernatant layer. Next, to remove the dimethyl sulfoxide, 190 mL of methanol was added to the white solid layer and washed four times in the same manner. Finally, the glass container containing the white solid layer was placed in a desiccator at 40 ° C. and dried under reduced pressure for 24 hours, and 0.50 g of white solid was recovered.

<Specific surface area>
The BET specific surface area of the porous zinc complex of this example was 1,481 ^{m 2} /g, and the pore volume was 0.82 mL/g. The nitrogen adsorption isotherm of the porous zinc complex of this example is shown in Figure 6-1. In Figure 6-1, the solid line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during adsorption in Example 3, and the dashed line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during desorption in Example 3.

<Thermal decomposition temperature>
The thermal decomposition temperature of the porous zinc complex of this example was 425° C., and the TG curve is shown in FIG. 6-2.

<Particle size>
It was confirmed that the porous zinc complex of this example was composed of aggregated nanoparticles of up to 100 nm in size. The SEM image is shown in Figure 6-3.

Example 4
<Synthesis>
(Reaction Step 1) The 1.0 mol/L diethylzinc dimethyl sulfoxide solution of Example 3 was used.

(Reaction Step 2) Synthesis of Porous Zinc Complex (2-Ethylimidazole Zinc Salt)
In a glove box under a slightly pressurized nitrogen atmosphere, zirconia balls (10 mm diameter), 0.96 g (10.0 mmol) of 2-ethylimidazole, and 2.0 mL of a 1.0 mol/L diethylzinc dimethyl sulfoxide solution (2.0 mmol of diethylzinc) were placed in a ball mill container and sealed. The sealed container was set to a planetary ball mill (P-6 manufactured by Fritsch), and kneading treatment was carried out at a rotation speed of 150 rpm for 30 minutes.

(purification process)
After the kneading treatment, the cloudy slurry was recovered and separated into a white solid layer and a colorless, transparent supernatant layer by centrifugation (Kokusan Co., Ltd., H-103N, rotation speed 3,400 rpm, rotation time 30 min), and the supernatant layer was removed. Subsequently, to remove any remaining unreacted ligand, 190 mL of dimethyl sulfoxide was added to the white solid layer, and the mixture was washed four times by centrifugation and removal of the supernatant layer. Next, to remove the dimethyl sulfoxide, 190 mL of methanol was added to the white solid layer and washed four times in the same manner. Finally, the glass container containing the white solid layer was placed in a desiccator at 40 ° C. and dried under reduced pressure for 24 hours, and 0.52 g of white solid was recovered.

<Specific surface area>
The BET specific surface area of the porous zinc complex of this example was 1,198 ^{m 2} /g, and the pore volume was 4.7 mL/g. The nitrogen adsorption isotherm of the porous zinc complex of this example is shown in Figure 7-1. In Figure 7-1, the solid line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during adsorption in Example 4, and the dashed line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during desorption in Example 4.

<Thermal decomposition temperature>
The thermal decomposition temperature of the porous zinc complex of this example is 390° C., and the TG curve is shown in FIG. 7-2.

<Particle size>
It was confirmed that the porous zinc complex of this example was composed of aggregated nanoparticles of up to 100 nm in size. The SEM image is shown in Figure 7-3.

Example 5
<Synthesis>
(Reaction Step 1) The 1.0 mol/L diethylzinc dimethyl sulfoxide solution of Example 3 was used.

(Reaction Step 2) Synthesis of Porous Zinc Complex (Benzimidazole Zinc Salt)
In a glove box under a slightly pressurized nitrogen atmosphere, zirconia balls (10 mm diameter), 1.44 g (10.0 mmol) of benzimidazole, and 2.0 mL of a 1.0 mol/L diethylzinc dimethyl sulfoxide solution (2.0 mmol of diethylzinc) were added to a ball mill container and sealed. The sealed container was set to a planetary ball mill (P-6 manufactured by Fritsch), and kneading treatment was performed at a rotation speed of 150 rpm for 30 minutes.

(purification process)
After the kneading treatment, the cloudy slurry was recovered and separated into a white solid layer and a colorless, transparent supernatant layer by centrifugation (Kokusan Co., Ltd., H-103N, rotation speed 3,400 rpm, rotation time 30 min), and the supernatant layer was removed. Subsequently, to remove any remaining unreacted ligand, 190 mL of dimethyl sulfoxide was added to the white solid layer, and the mixture was washed four times by centrifugation and removal of the supernatant layer. Next, to remove the dimethyl sulfoxide, 190 mL of methanol was added to the white solid layer and washed four times in the same manner. Finally, the glass container containing the white solid layer was placed in a desiccator at 40 ° C. and dried under reduced pressure for 24 hours, and 0.71 g of white solid was recovered.

<Specific surface area>
The BET specific surface area of the porous zinc complex of this example was 284 ^{m 2} /g, and the pore volume was 0.41 mL/g. The nitrogen adsorption isotherm of the porous zinc complex of this example is shown in Figure 8-1. In Figure 8-1, the solid line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during adsorption in Example 5, and the dashed line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during desorption in Example 5.

<Thermal decomposition temperature>
The thermal decomposition temperature of the porous zinc complex of this example was 515° C., and the TG curve is shown in FIG. 8-2.

<Particle size>
It was confirmed that the porous zinc complex of this example was composed of aggregated nanoparticles of up to 250 nm. The SEM image is shown in Figure 8-3.

Example 6
<Synthesis>
(Reaction Step 1) Preparation of 1.0 mol/L N,N-dimethylformamide solution of diethylzinc 162 mL of N,N-dimethylformamide was added to a glass flask (volume 300 mL) under a slightly pressurized nitrogen atmosphere, and the liquid temperature in the flask was cooled to -10 ° C while stirring. Once the liquid temperature stabilized in the range of -11 ° C to -9 ° C, the dropwise addition of 17 mL of diethylzinc was started, and the dropwise addition rate was adjusted so that the liquid temperature in the flask was maintained within the temperature range of -11 ° C to -9 ° C. After the dropwise addition, the mixture was aged at -10 ° C for 1 hour and then heated to 20 ° C at a constant rate over 100 minutes. After the liquid temperature in the flask reached 20 ° C, the mixture was aged for 6 hours at a liquid temperature of 20 ° C. 169 g of a colorless, transparent solution was recovered.

(Reaction Step 2) Synthesis of Porous Zinc Complex (1,4-Benzenedicarboxylic Acid Zinc Salt)
A glass flask (volume: 300 mL) was charged with 15 mL of N,N-dimethylformamide under a slightly pressurized nitrogen atmosphere, and 11 mL of a 1.0 mol/L solution of diethylzinc in N,N-dimethylformamide (10.4 mmol of diethylzinc) was added. The temperature inside the flask was cooled to -10°C while stirring. Once the liquid temperature stabilized within the range of -11°C to -9°C, 64.3 g of a previously prepared 2.1 wt% solution of 1,4-benzenedicarboxylic acid in N,N-dimethylformamide (8.3 mmol of 1,4-benzenedicarboxylic acid) was added dropwise via a dropping funnel over 42 minutes, adjusting the rate so that the liquid temperature remained within the range of -10°C to -4°C. After the dropwise addition, the dropping funnel was washed with 10 mL of N,N-dimethylformamide, and the washings were added to the flask. Thereafter, the mixture was aged at -10°C for 1 hour, and then heated to 15°C over approximately 60 minutes at a constant rate (heating rate: 0.34°C/min). When the liquid temperature reached -1°C during the heating process, precipitation of white crystals was confirmed. After the liquid temperature reached 15°C, the mixture was immersed in a 152°C bath and heated to 150°C over 40 minutes at a constant rate (heating rate: 3.5°C/min), and aging was initiated at a liquid temperature of 150°C. After 13 hours of aging, the conversion of diethylzinc from the supernatant liquid in the flask was measured by ^1H -NMR and found to be 99% or more, so 79 g of an orange turbid slurry was recovered.

(purification process)
To extract the porous zinc complex, the recovered orange turbid slurry was centrifuged to separate an orange solid layer and a colorless, transparent supernatant layer (Kokusan Co., Ltd., H-103N, rotation speed 2,800 rpm, rotation time 30 min), and the supernatant layer was removed. Subsequently, to remove any remaining unreacted ligand, 200 mL of N,N-dimethylformamide was added to the white solid layer, followed by centrifugation and removal of the supernatant layer, followed by washing three times. Next, to remove the N,N-dimethylformamide, 200 mL of dichloromethane was added to the white solid layer, followed by washing three times in the same manner (rotation speed 4,000 rpm, rotation time 15 min). Finally, the glass container containing the pale yellow solid layer was placed in a desiccator at 40 °C and dried under reduced pressure for 24 hours, recovering 1.5 g of pale yellow solid.

<Yield>
As a result of the chelate titration described above (porous zinc complex 52.0 mg, EDTA 0.146 mmol, ZnSO _0.119 mmol), the Zn concentration of the porous zinc complex of this example was 34.0 wt %. The Zn yield of this example, calculated from this Zn concentration, was 75%.

<Specific surface area>
The BET specific surface area of the porous zinc complex of this example was 628 ^{m 2} /g, and the pore volume was 0.86 mL/g. The nitrogen adsorption isotherm of this example is shown in Figure 9-1. In Figure 9-1, the solid line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during adsorption in Example 6, and the dashed line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during desorption in Example 6.

<Thermal decomposition temperature>
The TG curve of this example is shown in Figure 9-2. In Figure 7, in the curve showing the weight loss with increasing temperature, the approximate temperature at which the porous zinc complex of Example 6 is estimated to have thermally decomposed, i.e., the point where the extrapolated line on the low temperature side intersects with the extrapolated line on the high temperature side (shown by a black circle), was approximately 407°C.

<Particle size>
The porous zinc complex of this example was confirmed to have starfish-shaped particle morphology of about 200 nm. A TEM image of this example is shown in Figure 9-3.

Example 7
<Synthesis>
(Reaction Step 1) The 1.0 mol/L diethylzinc dimethylformamide solution of Example 6 was used.

(Reaction Step 2) Synthesis of Porous Zinc Complex (2,5-Dihydroxy-1,4-benzenedicarboxylic Acid Zinc Salt)
25 mL of dimethylformamide was added to a pressure-resistant stainless steel vessel (maximum operating pressure: 2 MPa, volume: 150 mL) under a slightly pressurized nitrogen atmosphere, followed by 5.0 mL of a 1.0 mol/L solution of diethylzinc in dimethylformamide (4.7 mmol of diethylzinc). The temperature inside the flask was cooled to -10°C while stirring. Once the liquid temperature stabilized within the range of -11 to -9°C, 11.6 g of a previously prepared 2.1 wt % solution of 2,5-dihydroxy-1,4-benzenedicarboxylic acid in dimethylformamide (1.2 mmol of 2,5-dihydroxy-1,4-benzenedicarboxylic acid) was added dropwise via a dropping funnel over 60 minutes, adjusting the rate so that the liquid temperature remained within the range of -10 to -4°C. After the dropwise addition, the dropping funnel was washed with 10 mL of dimethylformamide, and the washings were added to the flask. Thereafter, the mixture was aged at -10°C for 1 hour, and then heated to 15°C over approximately 60 minutes at a constant rate (heating rate: 0.34°C/min). After the liquid temperature reached 15°C, it was immersed in a 110°C bath and heated to 100°C over 48 minutes at a constant rate (heating rate: 2.0°C/min), and aging was initiated at a liquid temperature of 100°C. After 20 hours of aging, the conversion rate of diethylzinc from the supernatant liquid in the flask was measured by ^1H -NMR and found to be 99% or higher, so 50 g of an orange turbid slurry was recovered.

(purification process)
To extract the porous zinc complex, the recovered orange turbid slurry was separated into an orange solid layer and a colorless, transparent supernatant layer by centrifugation (Kokusan Co., Ltd., H-103N, rotation speed 3,500 rpm, rotation time 5 min), and the supernatant layer was removed. Subsequently, to remove any remaining unreacted ligand, 60 mL of dimethylformamide was added to the white solid layer, and the mixture was washed three times by centrifugation and removal of the supernatant layer. Next, to remove the dimethylformamide, 60 mL of methanol was added to the white solid layer, and the mixture was washed three times in the same manner (rotation speed 3,500 rpm, rotation time 5 min). Finally, the glass container containing the yellow solid layer was placed in a desiccator at 40 °C and dried under reduced pressure for 24 hours, and 0.35 g of a light yellow solid was recovered.

<Yield>
As a result of the chelate titration described above (porous zinc complex 54.0 mg, EDTA 0.142 mmol, ZnSO _0.109 mmol), the Zn concentration of the porous zinc complex of this example was 39.8 wt %. The Zn yield of this example, calculated from this Zn concentration, was 45%.

<Specific surface area>
The BET specific surface area of the porous zinc complex of this example was 401 ^{m 2} /g, and the pore volume was 0.41 mL/g. The nitrogen adsorption isotherm of this example is shown in Figure 10-1. In Figure 10-1, the solid line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during adsorption in Example 7, and the dashed line with black circles (●) shows the relationship between the relative pressure and the amount of N ₂ adsorbed during desorption in Example 7.

<Thermal decomposition temperature>
The thermal decomposition temperature in this example was 365° C. The TG curve of this example is shown in FIG.

<Particle size>
The porous zinc complex of this example was confirmed to have particle shapes of 200 nm or less. An SEM image of this example is shown in Figure 10-3.

The porous zinc complex of the present invention can be used for applications such as reaction catalysts, gas adsorption, gas separation, and gas storage.

Claims (7)

A method for producing a porous zinc complex , comprising the following first and second steps :
A first step of solvating an organozinc compound represented by the following general formula (1) with an aprotic solvent and aging the solvated organozinc compound to obtain a solution of the organozinc compound:
M ₁ -Zn-M ₂ (1)
(In formula (1), _M1 and _M2 each independently represent a linear, branched, or cyclic alkyl group having 20 or less carbon atoms, or a cyclic hydrocarbon group including an aromatic group having 20 or less carbon atoms.)
Here, the organic zinc compound includes dimethyl zinc, diethyl zinc, dipropyl zinc, diisopropyl zinc, dicyclopropyl zinc, dibutyl zinc, diisobutyl zinc, disec-butyl zinc, ditert-butyl zinc, dicyclobutyl zinc, dipentyl zinc, diisopentyl zinc, dineopentyl zinc, ditert-pentyl zinc, dicyclopentadienyl zinc, di(1-methylbutyl)zinc, di(2-methylbutyl)zinc, di(1,2-dimethylpropyl)zinc, di(1 di(4-ethylpropyl)zinc, di(cyclopentyl)zinc, dihexylzinc, di(cyclohexyl)zinc, di(4-methylcyclohexyl)zinc, diheptylzinc, dioctylzinc, dinonylzinc, didecylzinc, diundecylzinc, didodecylzinc, ditridecylzinc, diicosylzinc, diphenylzinc, dibenzylzinc, dinaphthylzinc, diadamantylzinc, diindecylzinc, diphenanthresylzinc, difluorenylzinc, or ditriphenylenylzinc.
A second step of reacting the organozinc compound solvated with an aprotic solvent obtained in the first step with one or more organic ligand raw materials selected from the group consisting of imidazole compounds having at least one imidazolyl group in the molecule and carboxylic acid compounds having at least two carboxy groups in the molecule in the presence of an inert gas . The manufacturing method described in claim 1, wherein the porous zinc complex has an oxygen atom concentration of 2.5 atm% or less, calculated from the photoelectron intensities of the O1s orbital (505-545 eV), C1s orbital (270-295 eV), N1s orbital (375-415 eV), and Zn2p orbital (995-1,035 eV) obtained by X-ray photoelectron spectroscopy, and the ratio of the number of oxygen atoms to the number of zinc atoms is 20 atm% or less. 3. The production method according to claim 1 , wherein the organic ligand raw material is 2-methylimidazole, 2-ethylimidazole, benzimidazole, 1,4-benzenedicarboxylic acid, or 2,5-dihydroxy-1,4-benzenedicarboxylic acid. The method according to any one of claims 1 to 3 , wherein the organozinc compound is diethylzinc, dipropylzinc, or diisopropylzinc. The production method according to any one of claims 1 to 4, wherein the aprotic solvent is one solvent or a mixed solvent of two or more solvents selected from the group consisting of heterocyclic aromatic solvents, furan solvents, thiophene solvents, nitrile solvents, lactam solvents, amide solvents, carbamide solvents, ketone solvents, sulfoxide solvents, ester solvents, and ether solvents. The manufacturing method described in any one of claims 1 to 4, wherein the aprotic solvent is pyridine, dimethyl sulfoxide, or N,N-dimethylformamide. The method according to any one of claims 1 to 6 , wherein the aprotic solvent has a water content of 50 ppm or less.