JP2010058034A - Characteristic-varying type switching material and switching method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a characteristic-varying type switching material which varies in characteristics in response to an external stimulus and changes to another material having the same composition but different properties and a switching method for achieving excellent characteristics for a magnetic material or an adsorbent. <P>SOLUTION: The characteristic-varying type switching material includes a polymer metal complex containing structural units of the formula [XY<SB>2</SB>L<SB>2</SB>]<SB>n</SB>(wherein, X is a divalent cation selected from the group consisting of those of cobalt, nickel and copper; Y is a counter ion containing at least three fluorine atoms; L is 1,4-bis(4-pyridyl)benzene) and enables switching between the gate-type and the I-type characteristics by using it. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a property change type switching material and a switching method using the same, and more particularly, a property comprising a polymer metal complex that undergoes property change by an external stimulus and can be switched to another compound having the same composition but different properties. It relates to the use of variable switching materials.

Polymer metal complexes composed of metal salts and multidentate ligands are attracting attention because they can be used for gas storage materials, sensors, catalysts, and the like. One of the features of this polymer metal complex is that the structure is easily changed as compared with carbon materials typified by activated carbon and inorganic materials typified by zeolite and silica gel. This is because carbon materials and inorganic materials are composed of strong covalent bonds and ionic bonds, while polymer metal complexes contain weak bonds such as hydrogen bonds and coordination bonds in the structure. It is thought to be from. For example, a polymer metal complex that causes a dynamic structural change by an external stimulus has been reported (see Non-Patent Document 1 and Non-Patent Document 2). Among these novel dynamic structural change metal complexes, when a polymer metal complex having a polymer structure and having a void inside is used as a gas adsorbent, as shown in FIG. Although a gas is not adsorbed up to the pressure (P ₁ ), a unique phenomenon has been observed that gas adsorption starts when a certain pressure P ₁ is exceeded. Although not releasing gas until a constant pressure P ₂ with respect to gas emission, it is observed at the same time the phenomenon of rapid release gas becomes to a constant pressure P ₂ less. Such a complex is called a gate-type polymer complex. For example, an interdigitate complex obtained from 2,5-dihydroxybenzoic acid, 4,4′-bipyridyl and copper is known as a specific example. Therefore, the expectation of utilization as a gas storage material is increasing (see Non-Patent Document 3 and Non-Patent Document 4).

  This phenomenon occurs when the polymer complex changes to a structure different from that before the application of the gas. However, the structure change complex that has been known to date has a low gas pressure. The structure before the gas application is always restored, and polymer complexes having different structures before and after application cannot be taken out as separate substances. That is, when the gas application is stopped (when the gas pressure is lowered), the gate-type polymer complex changes to the original structure, so that the gas must be continuously applied to maintain the structure.

In addition, the gate-type polymer complex generally has a small difference between the adsorbing pressure P ₁ and the releasing pressure P ₂ , and by using this, it is possible to repeatedly store and release the gas with a small pressure difference. This is advantageous for applications such as pressure swing adsorption. However, as described above, the gate-type polymer complex, it takes a certain pressure for adsorbing gas adsorption at a very low pressure P ₀ from P _1, when you want to implement the release action, around P ₀ So-called non-structural changes such as substances whose adsorption amount increases in proportion to the gas pressure from a low pressure, such as a complex having a three-dimensional skeleton of jungle gym synthesized from zinc and dicarboxylic acids, collectively called MOF A type I complex or the like in the IUPAC classification (see Non-Patent Document 5 and Non-Patent Document 6) is suitable. In other words, the complex exhibiting the gate-type behavior and the complex exhibiting the I-type behavior are different from each other. Therefore, when it is desired to switch both the gate-type adsorption and the I-type adsorption, the gate-type polymer complex is used. And non-gate complex adsorption towers were installed separately, and they had to be switched and used.
Kazuhiro Uemura, Susumu Kitagawa, Future Materials, (2002) December issue, 44 Ryotaro Matsuda, Susumu Kitagawa, Petrotec, (2003) Vol. 26, No. 2, pp. 97-104 Kitagawa, S. et al., Angewandte Chem. Int. Ed. (2003) 428 Seki, K. et al., Phys. Chem. Chem. Phys., (2002) 4, 1968 Kondo et al., "Science of adsorption", Maruzen Co., Ltd., page 28 Yaghi, OM et al., J. Am. Chem. Soc. (2005) 17998

  An object of the present invention is to provide a property-changing switching material having excellent characteristics as a magnetic material or an adsorbing material.

  Another object of the present invention is to provide a switching method of a characteristic change type switching material that exhibits excellent characteristics as a magnetic material or an adsorbing material.

  As a result of intensive studies to solve the problems as described above, the present inventors have found that a divalent metal ion selected from cobalt, nickel, and copper, and a counter ion containing three or more fluorine atoms. The polymer metal complex containing 1,4-bis (4-pyridyl) benzene changes to another structure when the gas is applied, but does not return to the original structure even when the gas application is stopped, and It has been found that it has two characteristics of a gate type and an I type, and the present invention has been completed.

That is, the present invention
(1) Unit structure of the following formula (i)
[XY ₂ L ₂ ] _n ... (i)
(Wherein, X is any divalent cation selected from the group consisting of cobalt, nickel, and copper, Y is a counter ion containing 3 or more fluorine atoms, and L is 1,4. A change-of-characteristic switching material characterized in that it can be switched between a gate-type property and an I-type property using a switching material, and a polymer metal complex having a bis (4-pyridyl) benzene)
(2) The change from the gate type to the I type is performed by applying one or more switching gases selected from the group consisting of nitrogen, carbon dioxide, methane, ethane, and oxygen. Type switching material,
(3) Switching from the I type to the gate type is performed by bringing a hydroxyl group-containing low molecular weight substance into contact with each other.
(4) The property-changing switching material according to (3), wherein the hydroxyl group-containing low molecular weight substance is at least one selected from the group consisting of water and an alcohol having a boiling point of 100 ° C. or lower,
(5) The property-changing switching material according to any one of (1) to (4), wherein the polymer metal complex has a structure in which units of a two-dimensional network structure are stacked.
(6) The counter ion Y containing three or more fluorine ions is any one selected from the group consisting of a fluoride ion, a trifluoromethanesulfonate ion, and a trifluoro (trifluoro) borate (1) The characteristic change type switching material according to any one of to (5),
(7) The property change switching material according to any one of (1) to (6), wherein X is nickel ion, and Y is borofluoride ion,
(8) The property-changing switching material according to any one of (1) to (7) is changed from a gate-type polymer complex to an I-type complex by applying a switching gas, and an I-type complex is obtained (1 ) To (7), the switching method of the characteristic change type switching material characterized by changing the characteristic change type switching material into a gate type complex by contact with a hydroxyl group-containing low molecular weight substance,
(9) The switching method of the property change switching material according to (8), wherein the switching gas is at least one selected from the group consisting of nitrogen, carbon dioxide, methane, ethane, and oxygen,
(10) The method for switching a property-changing switching material according to (8) or (9), wherein the hydroxyl group-containing low-molecular substance is at least one selected from the group consisting of water and an alcohol having a boiling point of 100 ° C. or lower. ,
It is.

  The property-changing type switching material of the present invention switches between an I-type material that adsorbs gas from a low pressure and a gate type polymer complex that adsorbs and releases gas suddenly above a certain pressure, depending on the application. Can be used. Here, the gate-type polymer complex does not adsorb gas up to a certain pressure, but adsorbs gas abruptly at a predetermined pressure or higher, and vice versa, that is, does not release gas up to a certain pressure but does not release a predetermined pressure. In the following, it refers to a complex that exhibits a phenomenon in which gas is rapidly released. The I-type complex refers to a complex that exhibits a phenomenon in which the amount of adsorption increases in proportion to the gas pressure. The characteristic change type switching material according to the present invention is, for example, a state before the gas is applied even if the gas application is stopped (gas pressure is lowered) after the gate type behavior is exhibited by the application of a predetermined gas pressure. The structure never returns. Therefore, after releasing the gas, it can be used as a polymer metal complex that continuously exhibits type I behavior.

  As another use of the property change type switching material of the present invention, when nickel ion, cobalt ion, or the like is used as a metal ion, the spin crossover complex can change the spin state by structural change. It can be used for recording materials.

The characteristic change type switching material of the present invention comprises a polymer metal complex represented by the following formula (i). Here, the following formula (i) has n indicating the repetition of the unit structure, but merely indicates that the unit structure of the formula (i) is repeated, and the range of n is not particularly limited. Moreover, the characteristic change type switching material in the present invention includes a case where it contains a component other than the polymer metal complex represented by the following formula (i) as described later.
[XY ₂ L ₂ ] _n ... (i)
(Wherein, X is any divalent cation selected from the group consisting of cobalt, nickel, and copper, Y is a counter ion containing 3 or more fluorine atoms, and L is 1,4. -Represents bis (4-pyridyl) benzene)

  The unit structure of the polymer metal complex in the present invention is a so-called two-dimensional structure in which a ligand (L) having a metal ion (X) as an intersection and a coordination point at both ends of an elongated shape is coordinated to a metal. A network layer is formed. Further, a plurality of two-dimensional network layers are adjacent to the fluorine ions of the counter ion (Y) via the counter ion (Y) coordinated to the metal ion (X), that is, the two-dimensional network layer. The layers are three-dimensionally stacked with hydrogen bonds formed between them.

  About the characteristic change type switching material of this invention, in the range which does not prevent the expression of a characteristic change type switching function, it is preferable from a viewpoint of improving a function and stability. Additives include, for example, excipients for processing into molded bodies so that they are easy to handle, endothermic agents that absorb heat generated during substance adsorption to increase thermal stability, Adsorption characteristics obtained by adding the adsorption function and the characteristic change type switching function of the present invention, that is, the characteristic change type switching function of the present invention appears after adsorbing a certain amount or more of gas, or the characteristic change type of the present invention In the case where the switching function is manifested and thereafter a characteristic that adsorbs gas in the form of I is required, it is preferable to add a known so-called type I adsorbent such as activated carbon, zeolite, or polymer complex.

  The amount of these additives to be added is determined according to the required characteristics and cannot be determined in general. However, in the case of an excipient or endothermic agent, external stimuli are caused by the excipient or endothermic agent. In order to prevent the switching efficiency from being cut off, the addition rate of the excipient or the endothermic agent is preferably 50% by mass or less. When an I-type adsorbent is added, the mixing ratio may be determined according to the required I-type adsorption characteristic and the characteristic balance of the characteristic change type switching function of the present invention. These additives may be used alone or in combination.

The raw material for synthesize | combining the compound represented by Formula (i) is illustrated.
One of the raw material is a metal salt having the composition of XY _2. Here, X is any divalent metal ion selected from the group consisting of cobalt, nickel, and copper. These metal ions are preferable because they have a strong interaction with a counter ion containing 3 or more fluorine atoms and 1,4-bis (4-pyridyl) benzene and can easily form a two-dimensional network monolayer. Further, Y as a counter ion of X needs to contain 3 or more fluorine atoms. This is because the interaction between the layers is a hydrogen bond between a counter ion and 1,4-bis (4-pyridyl) benzene, so that the presence of three or more fluorine atoms is important. Specific examples of the counter ion containing 3 or more fluorine atoms include borofluoride ion, trifluoromethanesulfonate ion, pentafluoroethanesulfonate ion, and trifluoro (trifluoro) borate. Of these, a fluoride ion, a trifluoromethanesulfonate ion, and a trifluoro (trifluoro) borate are preferable in that the size of the ions is not so large and does not hinder the formation of a laminated structure. When the number of fluorine atoms is less than 3, for example, methanesulfonate ion or the like weakens the interaction, and an appropriate laminated structure cannot be formed. Further, counter ions containing elements other than fluorine that can form hydrogen bonds, such as nitrate ions and sulfate ions, form hydrogen bonds with 1,4-bis (4-pyridyl) benzene to form a laminated structure. However, since the hydrogen bond is too strong, the structural change does not occur.

  L in the formula (i) is 1,4-bis (4-pyridyl) benzene. Even with pyridyl-type ligands, bipyridine and pyrazine, which have fewer aromatic rings than 1,4-bis (4-pyridyl) benzene, have a weaker interaction with a counter ion containing three or more fluorine atoms, Since an appropriate laminated structure is not formed, it is not preferable. In addition, 4,4′-bis (4-pyridyl) biphenyl and the like having a large number of aromatic rings are not preferable because π-π interaction between ligands between layers becomes strong and structural change is difficult.

  In the present invention, in order to produce the compound represented by formula (i), it is necessary to dissolve the metal salt of the raw material and the organic ligand in a solvent and mix these two liquids. As a solvent for dissolving the metal salt, it is essential to use a solvent having a hydroxyl group such as water or alcohol. In addition to being easy to dissolve the metal salt, these hydroxyl group-containing solvents form hydrogen bonds between the counter ion and the ligand in the process of forming the laminated structure of the property-changing switching material. Therefore, it is important to use a solvent containing these hydroxyl groups.

  Examples of the alcohol include aliphatic monohydric alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol and 2-butanol, and aliphatic dihydric alcohols such as ethylene glycol. Methanol, ethanol, 1-propanol, and 2-propanol are preferable because they are inexpensive and have high solubility of metal salts. In addition, these alcohols may be used alone, or a plurality of alcohols may be used in combination.

  It is also preferable to use a mixture of water and the alcohol as a solvent. The mixing ratio is preferably 0: 100 to 80:20 (volume ratio). If the volume ratio of water exceeds 80, the ligand is difficult to dissolve, which is not preferable.

  Further, it is also possible to use water, alcohol, or a mixed solvent of water-alcohol in addition to an organic solvent other than alcohol. The organic solvent to be mixed is a solvent miscible with water, and examples thereof include acetonitrile, tetrahydrofuran, acetone, 1,4-dioxane, dimethylformamide, dimethyl sulfoxide and the like. These may be used singly or in combination of two or more. Among these, one or more selected from the group consisting of acetone, 1,4-dioxane, dimethylformamide, dimethyl sulfoxide, and acetonitrile is preferable because the layered structure can be easily developed. The mixing ratio of the organic solvent is 50% by volume or less, preferably 30% by volume or less.

  On the other hand, as the solvent for dissolving the organic ligand, alcoholic solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and ethylene glycol, acyclic or cyclic such as ether and tetrahydrofuran Aliphatic ethers, ketones such as acetone, esters such as ethyl acetate, aliphatic nitriles such as acetonitrile, halogenated solvents such as dichloromethane, aromatic solvents such as benzene and toluene, formamides such as dimethylformamide, dimethyl Sulfoxides such as sulfoxide can be widely exemplified. These may be used singly or in combination of two or more. In terms of cost and solubility, methanol, ethanol, 2-propanol, acetonitrile, acetone and the like are preferable.

  The method for mixing the metal salt solution and the organic ligand solution may be the addition of the organic ligand solution to the metal salt solution or vice versa. Regarding the concentration of the solution, the metal salt solution is 40 mmol / L to 4 mol / L, preferably 80 mmol / L to 2 mol / L, and the organic solution of the ligand is 40 mmol / L to 3 mol / L, preferably 80 mmol / L to It should be 1.8 mol / L. Even if the reaction is carried out at a concentration lower than this, the desired product can be obtained, but this is not preferable because the production efficiency is lowered. A concentration higher than this is not preferable because the switching ability is lowered.

  The reaction temperature is −20 to 120 ° C., preferably 15 to 90 ° C. If it is carried out at a lower temperature than this, the solubility of the raw material is lowered, which is not preferable. Although it is possible to carry out the reaction at a higher temperature using an autoclave or the like, there is no substantial meaning because the yield does not improve for the energy cost such as heating.

  The mixing ratio of the metal salt and the organic ligand used in the reaction of the present invention is in the range of 3: 1 to 1: 4, preferably 1.5: 1 to 1: 3. Is good. In other ranges, the yield of the target product decreases, and unreacted raw materials remain, making it difficult to take out the target product.

  The reaction can be carried out using an ordinary glass-lined SUS reaction vessel and a mechanical stirrer. After completion of the reaction, the target substance and raw material can be separated by filtration and drying to produce a target substance with high purity.

  The characteristic change type switching material of the present invention can switch both characteristics of a gate type polymer complex that exhibits gas adsorption as a gate and an I type complex that adsorbs gas as an I type by using a switching material. is there. In order to switch from a gate-type polymer complex to an I-type complex, a switching gas may be used as a switching material and applied at a pressure higher than the gate pressure. As the switching gas, molecules with a molecular exclusive area of am [see McClellan, ALJ Colloid Interface Sci., 23, 577 (1967)] of 0.125 nm or more, specifically nitrogen, carbon dioxide, methane, ethane, oxygen, etc. This is preferable in terms of efficient switching. Am of less than 0.125, such as hydrogen molecules, is not preferable because it has a small occupied area, a small influence when a gas is applied to the property change type switching material, and a low switching capability.

  In order to switch from the I-type complex to the gate-type polymer complex, a hydroxyl group-containing low molecular weight substance having a hydroxyl group such as water or alcohol may be contacted as a switching material. Hydroxyl groups are preferred in that they can be efficiently switched by acting on hydrogen bonds in the structure-changing switching material. Specific examples of the alcohol include alcohols having a boiling point of 100 ° C. or lower, such as methanol, ethanol, and propanol. Alcohols having a boiling point exceeding 100 ° C. are not preferable because they are difficult to remove and may remain in the polymer complex, leading to a decrease in physical properties such as a decrease in adsorption capacity. The addition amount of the low molecular weight substance having a hydroxyl group such as water or alcohol is preferably a mass ratio of polymer complex: solvent = 1: 1 to 1:50. If the amount of the low-molecular substance used is less than 1: 1 in the above ratio, switching may be incomplete, such being undesirable. Switching is possible even when the amount of the low-molecular substance used exceeds 1:50 in the above ratio, but it is not preferable because a large amount of low-molecular substance needs to be removed. A low molecular weight substance having no hydroxyl group is not preferable in that the switching efficiency of the structure change switching material is low. The hydroxyl group-containing low molecular weight substance may be used in a liquid state (solvent of the polymer metal complex) or as a gas.

  Spin crossover refers to a phenomenon in which the number of unpaired electrons changes according to the surrounding environment, that is, pressure and temperature. The characteristic change type switching material of the present invention is expected to be applied to magnetic recording materials and the like. This is because the polymer metal complex of the present invention containing ions such as cobalt and nickel may exhibit such a spin crossover phenomenon.

  In the following Examples, nickel (II) tetrafluoroborate and copper (II) tetrafluoroborate used Aldrich products. Cobalt (II) trifluoromethanesulfonate was synthesized from the reaction of cobalt (II) chloride with silver trifluoromethanesulfonate. Aldrich products were used for silver trifluoromethanesulfonate and cobalt (II) chloride. In addition, special solvents manufactured by Kanto Chemical Co., Ltd. were used as various solvents. Furthermore, 1,4-bis (4-pyridyl) benzene is obtained from 1,4-phenylenebisboronic acid and 4-bromopyridine by the Suzuki coupling method using palladium (Transition Metal Reagents and Catalysts. Tsuji, J. Wiley (2000) p66.).

Example 1
To a water-methanol solution of nickel (II) tetrafluoroborate (water / methanol volume ratio = 4/1, 100 mL, 80 mmol / L), an ethanol solution of 1,4-bis (4-pyridyl) benzene (200 mL, 80 mmol / L) was added. L) was slowly laminated, sealed and left for 20 days. The precipitated powder was filtered under reduced pressure, washed with ethanol and water, and dried under reduced pressure at room temperature (25 ° C.) to obtain a light blue polymer metal complex crystal in a yield of 59%.

In order to determine the composition of the obtained crystal, X-ray crystal structure analysis was carried out using the large synchrotron radiation facility SPring-8 BL02B2 and analysis software RIETAN software. The result is shown in FIG. 1, and a schematic diagram is shown in FIG. FIG. 2 (b) shows a contrast of the abbreviations of the constituent elements for schematicizing FIG. 1 in FIG. 2 (a). From FIG. 1 and FIG. 2 (a), a two-dimensional network structure composed of 1,4-bis (4-pyridyl) benzene in which tetrafluoroborate ions are coordinated at the top and bottom of nickel ions, with nickel ions as intersections. It became clear that they were laminated. At the same time, the structural formula was found to be [Ni (BF ₄ ) ₂ (bpb) ₂ ] _n (bpb represents 1,4-bis (4-pyridyl) benzene).

  The nitrogen adsorption characteristics at 77K of the polymer metal complex obtained above were investigated. For the measurement, a BET automatic adsorption device (manufactured by Nippon Bell Co., Ltd.) was used, and the sample (the obtained polymer metal complex) was vacuum-dried at 90 ° C. for 2 hours prior to measurement, and a trace amount may remain. Some solvent molecules were removed. As a result of measuring the nitrogen adsorption characteristics, no adsorption of nitrogen was observed until the relative pressure was about 0.2, and a sudden increase in the amount of adsorption was confirmed around 0.2. It was found (see FIG. 3). 3-7, the horizontal axis of the figure is the relative pressure of nitrogen at 77K, the vertical axis is the amount of nitrogen adsorbed, and the unit is mL / g. It was also revealed that the adsorbed nitrogen was almost desorbed by the pressure reducing operation at the time of measurement.

  When the above-mentioned polymer metal complex used for nitrogen gas adsorption was examined again for nitrogen gas adsorption characteristics at 77 K without exposing it to the atmosphere, it showed I-type adsorption (see FIG. 4). That is, it was found that the gate type polymer complex can be switched to the I type complex by the first nitrogen gas application. It was also revealed that the adsorbed nitrogen was almost desorbed by the pressure reducing operation at the time of measurement.

  When the nitrogen gas adsorption characteristics of this type I complex were examined again at 77K, it again showed type I adsorption. That is, it was revealed that the present polymer metal complex stably maintains a structure exhibiting type I (see FIG. 5). It was also revealed that the adsorbed nitrogen was almost desorbed by the pressure reducing operation at the time of measurement.

  Furthermore, this type I complex was exposed to the atmosphere at room temperature (25 ° C.) for 1 hour, then vacuum dried at 90 ° C. for 2 hours, and then subjected to nitrogen adsorption measurement at 77 K. The relative pressure was about 0.2. Until this time, no adsorption of nitrogen was observed, and a rapid increase in the amount of adsorption was confirmed around 0.2 (see FIG. 6). That is, it was revealed that the type I complex can be switched to the gate type polymer complex by exposure to the atmosphere.

  Also, instead of exposing this type I complex to the atmosphere, ethanol was added to the measuring vessel, held at room temperature (25 ° C) for 1 hour, vacuum dried at 90 ° C for 2 hours, and then adsorbed with nitrogen at 77K. As a result of the measurement, no adsorption of nitrogen was observed until the relative pressure was about 0.2, and an abrupt increase in the amount of adsorption was confirmed around 0.2 (see FIG. 7). That is, it was revealed that the type I complex can be switched to the gate type polymer complex by contact with ethanol.

(Example 2)
To a water-methanol solution of cobalt (II) trifluoromethanesulfonate (water / methanol volume ratio = 1/1, 100 mL, 80 mmol / L), a methanol / ethanol solution of 1,4-bis (4-pyridyl) benzene (methanol) / Ethanol volume ratio = 1/5, 200 mL, 80 mmol / L) was slowly laminated, sealed, and allowed to stand for 20 days. The precipitated powder was filtered under reduced pressure, washed with ethanol and water, and dried under reduced pressure at room temperature (25 ° C.) to obtain a light pink polymer metal complex crystal in a yield of 45%.

As a result of structural analysis of the obtained crystals in the same manner as in Example 1, 1,4-bis (4-pyridyl) benzene having cobalt ions as intersections and coordinated with trifluoromethanesulfonate ions above and below the cobalt ions, respectively. It was revealed that the two-dimensional network structure consisting of At the same time, the structural formula was found to be [Co (OTf) ₂ (bpb) ₂ ] _n (OTf represents trifluoromethanesulfonate, and bpb represents 1,4-bis (4-pyridyl) benzene, respectively).

  The nitrogen adsorption property of the obtained polymer metal complex was investigated in the same manner as in Example 1. Adsorption of nitrogen was not observed until the relative pressure was about 0.3, and a sudden increase in the amount of adsorption was confirmed around 0.3, which proved to be a compound exhibiting so-called gate-type adsorption. It was also revealed that the adsorbed nitrogen was almost desorbed by the pressure reducing operation at the time of measurement.

  When the above-mentioned polymer complex used for the adsorption of nitrogen gas was exposed to the atmosphere again at 77K without exposing it to the atmosphere, this time, it showed an I-type adsorption. That is, it was found that the gate type polymer complex can be switched to the I type complex by the first nitrogen gas application. It was also revealed that the adsorbed nitrogen was almost desorbed by the pressure reducing operation at the time of measurement.

  When the nitrogen gas adsorption characteristics of this type I complex were examined again at 77K, it again showed type I adsorption. That is, it has been clarified that the polymer metal complex stably maintains a structure exhibiting type I.

  Further, switching of this type I complex to a gate type polymer complex was attempted in the same manner as in Example 1. As a result, it was confirmed that the gas was rapidly adsorbed when the relative pressure exceeded 0.3 by any method of exposure to air and addition of ethanol. That is, it became clear that the type I complex can be switched to the gate type polymer complex by moisture or ethanol.

(Example 3)
To a water-methanol solution of copper (II) borofluoride (water / methanol volume ratio = 1/1, 100 mL, 80 mmol / L), a methanol / ethanol solution of 1,4-bis (4-pyridyl) benzene (methanol / Ethanol volume ratio = 1/5, 200 mL, 80 mmol / L) was slowly laminated, sealed, and allowed to stand for 20 days. The precipitated powder was filtered under reduced pressure, washed with ethanol and water, and dried under reduced pressure at room temperature (25 ° C.) to obtain a light blue polymer complex crystal in a yield of 67%.

As a result of structural analysis of the obtained crystals in the same manner as in Example 1, from 1,4-bis (4-pyridyl) benzene having copper ions as intersections and fluoride ions coordinated above and below the copper ions, respectively. It was revealed that the two-dimensional network structure is stacked. At the same time, it was revealed that the structural formula was [Cu (OTf) ₂ (bpb) ₂ ] _n (bpb represents 1,4-bis (4-pyridyl) benzene).

  The nitrogen adsorption characteristics of the obtained polymer complex were investigated in the same manner as in Example 1. Nitrogen adsorption was not observed until the relative pressure was about 0.2, and a sudden increase in the amount of adsorption was confirmed when the relative pressure exceeded 0.2, indicating that the compound exhibited so-called gate-type adsorption. It was also revealed that the adsorbed nitrogen was almost desorbed by the pressure reducing operation at the time of measurement.

  When the above-mentioned polymer complex used for the adsorption of nitrogen gas was exposed to the atmosphere again at 77K without exposing it to the atmosphere, this time, it showed an I-type adsorption. That is, it was found that the gate type polymer complex can be switched to the I type complex by the first nitrogen gas application. It was also revealed that the adsorbed nitrogen was almost desorbed by the pressure reducing operation at the time of measurement.

  When the nitrogen gas adsorption characteristics of this type I complex were examined again at 77K, it again showed type I adsorption. That is, it has been clarified that the polymer metal complex stably maintains a structure exhibiting type I.

  Further, switching of this type I complex to a gate type polymer complex was attempted in the same manner as in Example 1. As a result, in any method of exposure to the atmosphere and addition of ethanol, rapid gas adsorption was confirmed when the relative pressure exceeded 0.2. That is, it became clear that the type I complex can be switched to the gate type polymer complex by moisture or ethanol.

(Comparative Example 1)
A solution of 4,4′-bipyridyl in ethanol (80 mmol / L) was slowly laminated on an aqueous solution of copper (II) borofluoride (80 mmol / L), sealed, and allowed to stand for 20 days. The precipitated powder was filtered under reduced pressure and dried under reduced pressure to obtain a dark blue polymer metal complex crystal in a yield of 63%.

The following experiment was conducted to determine the composition of the obtained crystal. The obtained crystals were dried at 90 ° C. for 3 hours under reduced pressure of 5 Pa, 1.00 g was weighed under an argon stream, and the powder was dissolved in 1 mol / L aqueous ammonia and extracted with dichloromethane. Dichloromethane was distilled off with a rotary evaporator, and the obtained solid was analyzed using a gas chromatograph mass spectrometer (QP5050A, Shimadzu Corporation). As a result, it was 4,4′-bipyridyl, and 55.8% by mass in the crystal. It was found that it was included. Further, the content of copper (II) ions in the aqueous ammonia layer was examined by ICP emission method. As a result, it was 12.3% by mass. Further, the content of fluorine atoms in the aqueous ammonia layer was examined by distillation separation spectrophotometry, and as a result, it was found to be 28.9% by mass. The composition of the crystals obtained by combining these was found to be [Cu (BF ₄ ) ₂ (bpy) ₂ ] _n (bpy represents 4,4′-bipyridyl).

  The nitrogen adsorption characteristic at 77K of the obtained gas adsorbent was investigated. For the measurement, a BET automatic adsorption apparatus (manufactured by Nippon Bell Co., Ltd.) was used, and the sample was vacuum dried at 120 ° C. for 3 hours prior to the measurement to remove solvent molecules that may remain in a trace amount. When the relative pressure was less than about 0.2, nitrogen adsorption was not observed, but when the relative pressure was 0.2 or more, an abrupt increase in the amount of adsorption was confirmed (see FIG. 8). Further, almost all of the gas adsorbed by depressurization was desorbed. 8 and 9, the horizontal axis of the figure is the relative pressure of nitrogen at 77 K, the vertical axis is the amount of nitrogen adsorbed, and the unit is mL / g.

  As the second measurement, the nitrogen adsorptivity was evaluated after the pretreatment at 120 ° C. for 3 hours as in the first measurement. As a result, as in the first measurement, nitrogen adsorption was not observed when the relative pressure was less than about 0.2, but a sudden increase in the amount of adsorption was confirmed at 0.2 or more (see FIG. 9). . Further, almost all of the gas adsorbed by depressurization was desorbed. That is, it was found that the polymer metal complex of this comparative example exhibited a gate-type behavior for the first time and the second time.

  The characteristic change type switching material of the present invention undergoes a characteristic change upon application of gas or the like. That is, it can be used as either a gate-type polymer complex or an I-type complex, and when used as an adsorbent, it can be easily converted into a gate-type polymer complex and an I-type complex depending on the type and purpose of the gas. Can be used by switching.

  In addition, in the case of complexes containing ions such as nickel and cobalt, there is a possibility that a spin crossover phenomenon in which the spin state changes with the change of characteristics may occur. In this case, in addition to the switching material, the recording material Etc. can also be used.

Structure of characteristic change type switching material of the present invention (result of X-ray crystal structure analysis) Structure of characteristic change type switching material of the present invention (schematic diagram) Gated gas adsorption isotherm of characteristic change type switching material of the present invention I-type gas adsorption isotherm of characteristic change type switching material of the present invention I-type gas adsorption isotherm of characteristic change type switching material of the present invention Gate-like gas adsorption isotherm of structural change type switching material of the present invention Gate-like gas adsorption isotherm of structural change type switching material of the present invention Gas adsorption isotherms of polymer metal complexes obtained in comparative examples Gas adsorption isotherms of polymer metal complexes obtained in comparative examples Schematic diagram showing gas adsorption and desorption in gated polymer complexes

Claims (10)

Unit structure of the following formula (i)
[XY ₂ L ₂ ] _n ... (i)
(Wherein, X is any divalent cation selected from the group consisting of cobalt, nickel, and copper, Y is a counter ion containing 3 or more fluorine atoms, and L is 1,4. A characteristic change type switching material comprising a polymer metal complex having bis (4-pyridyl) benzene) and capable of switching between gate-type characteristics and I-type characteristics using a switching material.   2. The property change type switching material according to claim 1, wherein the switching from the gate type to the I type is performed by applying at least one switching gas selected from the group consisting of nitrogen, carbon dioxide, methane, ethane, and oxygen. .   The characteristic change type switching material according to claim 1, wherein switching from the I type to the gate type is performed by bringing a hydroxyl group-containing low molecular weight substance into contact.   The property change switching material according to claim 3, wherein the hydroxyl group-containing low molecular weight substance is at least one selected from the group consisting of water and an alcohol having a boiling point of 100 ° C or lower.   The property change switching material according to claim 1, wherein the polymer metal complex has a structure in which units of a two-dimensional network structure are laminated.   The counter ion Y containing three or more fluorine ions is any one selected from the group consisting of borofluoride ions, trifluoromethanesulfonate ions, and trifluoro (trifluoro) borate. Any one of the characteristic change type switching materials. The property change type switching material according to any one of claims 1 to 6, wherein the X is a nickel ion, and the Y is a fluoride ion.   The characteristic change type switching material according to any one of claims 1 to 7 is changed from a gate-type polymer complex to an I-type complex by application of a switching gas, and the I-type complex is formed. A switching method for a property-changing switching material, wherein the property-changing switching material according to claim 1 is changed to a gate-type complex by contact with a hydroxyl group-containing low-molecular substance.   The switching method of the characteristic change type switching material according to claim 8, wherein the switching gas is at least one selected from the group consisting of nitrogen, carbon dioxide, methane, ethane, and oxygen.   The method for switching a property-changing switching material according to claim 8 or 9, wherein the hydroxyl group-containing low molecular weight substance is at least one selected from the group consisting of water and an alcohol having a boiling point of 100 ° C or lower.

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