JP2008291061A - Proton-conducting coordination polymer complex compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly proton-conducting coordination polymer complex compound capable of realizing high conductivity beyond the limitation of improvement only by occluded water molecules and hydrogen. <P>SOLUTION: The proton-conducting coordination polymer complex compound contains water of crystallization in a one-dimensional column formed by a polymer complex compound in which a 2,3-pyrazinedicarboxylic acid, trans-1,2-bis(4-pyridyl)ethylene and a water molecule coordinate-bond to a pentacoordination metal ion, wherein a water molecule of the water of crystallization and the coordinate-bonding water molecule form a hydrogen bond. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coordination polymer complex compound having high proton conductivity.

  Materials having high conductivity have been proposed as solid electrolytes and ion exchange membranes for solid polymer fuel cells.

  Patent Document 1 discloses a porous coordination polymer compound composed of a metal ion and an organic ligand containing an anion moiety. As a specific example, a combination of silver ion and dpdse is shown. Has been. By making the valence of the organic ligand larger than the valence of the metal ion, it becomes easier to occlude cations and the conductivity is improved. However, there is a limit to improving the conductivity only by the occluded cations.

  Patent Document 2 proposes to improve proton conductivity by inserting water molecules between layers of coordination polymer metal complex R2dtoaM (R: alkyl group, dtoa: dithiooxamide, M: metal). Patent Document 3 proposes that water molecules and hydrogen are occluded between the coordination polymer metal complex R2dtoaM layers to improve proton conductivity and electron conductivity. However, there is a limit to improving the conductivity only by the occluded water molecules and hydrogen.

JP 2005-75870 A JP 2004-31173 A JP 2004-31174 A

  An object of the present invention is to provide a coordination polymer complex compound having high proton conductivity that can realize high conductivity exceeding the limit of improvement by only occluded water molecules and hydrogen.

  In order to achieve the above object, according to the present invention, 2,3-pyrazinedicarboxylic acid, trans 1,2-bis (4-pyridyl) ethylene, and a water molecule are coordinated to a pentacoordinate metal ion. A polymer complex compound formed by coordinate bonding, wherein crystal water is contained in a one-dimensional column formed by the complex compound, and the water molecule of the crystal water and the water molecule having the coordinate bond are hydrogen. Provided is a proton-conducting coordination polymer complex compound characterized by being bonded.

  According to the present invention, a water molecule having proton conductivity is provided as a part of the ligand, and the water molecule forms a hydrogen bond with the water molecule in the one-dimensional column. Compared with the case of using only water molecules, proton conductivity is improved.

The coordination polymer complex compound of the present invention has a composition in which one unit is represented by [M (C ₆ H ₂ N ₂ O ₄ ) (C ₆ H ₅ N) (H ₂ O)] _n · 1.5 nH ₂ O. Have Here, M is a pentacoordinate metal ion of any one of Zn, Cd, and Cu.

FIG. 1 shows a three-dimensional structure of one unit in an ORTEP diagram when the metal ion M is Zn. In the figure, the part surrounded by an ellipse with an arrow is the H ₂ O water molecule contained in [] of the above composition formula, and two white spheres are indicated by hydrogen (H) and “O5” and are partially hatched. The ellipsoid formed is oxygen (O). As shown in the figure, this water molecule is bonded as a single ligand to a pentacoordinated Zn ion (Zn1).

On the other hand, 1.5 nH ₂ O of crystal water described at the end of [] outside the above composition formula is not shown for convenience of illustration, but actually includes water molecules as crystal water.

  2 and 3 show a b-axis projection and a c-axis projection of the three-dimensional polymer structure, respectively.

Water molecules taken in as crystallization water in the column form hydrogen bonds with each other. Moreover, the water molecule as a ligand also forms a hydrogen bond with the water molecule as a neighboring ligand and a carboxy group. It is considered that protons can be conducted by the Grottas mechanism via these two types of hydrogen bonds.
That is, there are two water molecules as crystal water in the one-dimensional column formed in this way, and at the same time, one water molecule is coordinated to Zn as shown in FIG. In addition, since the water molecule as the ligand and the water molecule as the crystal water in the column form a hydrogen bond, proton conduction by the Grottas mechanism appears.

  In the structure of the present invention, the organic compound excluding water molecules is composed of 2,3-pyrazinedicarboxylic acid and trans 1,2-bis (4-pyridyl) ethylene. Here, 2,3-pyrazinedicarboxylic acid is difficult to replace with other organic compounds due to its constitution. On the other hand, trans 1,2-bis (4-pyridyl) ethylene can be replaced with any of the following organic compounds (A) to (K).

(A) trans-4,4′-azopyridine (B) 4,4′-azopyridine (C) bis (pyridyl) acetylene (D) 1,2-bis (4-pyridinyl) ethane (E) 4,4′- Bipyridine (F) 1,4-bis (4-pyridinyl) benzene (G) 4,2 ′: 5 ′, 4 ″ -terpyridine (H) 2,5-di-4-pyridinyl-pyrimidine (I) 3,6 -Di-4-pyridinyl-pyridazine (J) 2,5-di- (4-pyridinyl) pyrazine (K) 3,6-di-4-pyridyl-1,2,4,5-tetrazine Of course these organics When the compound is replaced with a compound, the composition of the one unit varies depending on the difference in composition between 2-bis (4-pyridyl) ethylene and the replaced organic compounds (A) to (K). Bis (4-pyridyl) ethylene and replace Structural formulas of organic compounds (A) to (K) are shown.

  A proton conductive coordination polymer complex compound according to the present invention was synthesized by the following procedure.

  Zinc (II) chloride (0.035 g, 0.25 mmol) was dissolved in 20 ml of water to obtain a solution A.

  2,3-pyrazinedicarboxylic acid (0.053 g, 0.25 mmol) and trans 1,2-bis (4-pyridyl) ethylene (0.046 g, 0.25 mmol) were dissolved in 10 ml of water to obtain a solution B.

  Solution A was slowly mixed with solution B. Here, “slowly” refers to a mixing speed in a range in which the reaction proceeds rapidly due to the stirring action during mixing and a powdery precipitate is not generated.

  The obtained mixed solution was allowed to stand at room temperature for 24 hours to obtain colorless crystals. Here, the “crystal” is a single crystal block having a height and width of about 0.1 mm or more, respectively, and means a size that allows subsequent single crystal X-ray structural analysis. In the powdery precipitate, the size of each powder particle is smaller than the above “crystal”, and each individual powder particle is usually an aggregate of a plurality of single particles or a large number of fine single crystals. In other words, although the powdery precipitates can obtain diffraction peaks on each crystal plane by powder X-ray diffraction, it is practically impossible to perform single crystal X-ray structural analysis on single crystals constituting individual particles.

  The colorless crystal obtained above was subjected to single-crystal X-ray structural analysis. As a result, 1 consisting of zinc, 2,3-pyrazinedicarboxylate, trans 1,2-bis (4-pyridyl) ethylene, and water molecules It was found that the unit was a coordination polymer complex compound having the structure of FIG. As shown in FIG. 2 and FIG. 3, this complex has a one-dimensional column structure. Water molecules as crystal water are taken into the column, and water molecules coordinated with zinc and hydrogen bonds. is doing. Thereby, high proton conductivity can be obtained as compared with a conventional structure in which water molecules are simply occluded.

  ADVANTAGE OF THE INVENTION According to this invention, the coordination polymer complex compound with high proton conductivity which can implement | achieve the high conductivity exceeding the limit of the improvement by only the occluded water molecule or hydrogen is provided.

FIG. 1 is a structural diagram showing one unit of the coordination polymer complex compound of the present invention. FIG. 2 is a b-axis projection showing the network structure of the coordination polymer complex compound of the present invention shown in FIG. FIG. 3 is a c-axis projection showing the network structure of the coordination polymer complex compound of the present invention shown in FIG. FIG. 4 is a structural diagram of various organic compounds that can be replaced with trans 1,2-bis (4-pyridyl) ethylene, which is a component of the coordination polymer complex compound of the present invention.

Claims (3)

  A polymer complex compound in which 2,3-pyrazinedicarboxylic acid, trans 1,2-bis (4-pyridyl) ethylene, and a water molecule are coordinated to a pentacoordinate metal ion, A proton-conducting coordination polymer comprising crystal water in a one-dimensional column formed by a compound, wherein the water molecules of the crystal water and the water molecules that are coordinated are hydrogen-bonded Complex compound.   2. The proton conductive coordination polymer complex compound according to claim 1, wherein the pentacoordinate metal ion is selected from Zn ion, Cd ion, and Cu ion. In Claim 1 or 2, it replaces with the said trans 1, 2-bis (4-pyridyl) ethylene, and the following (A)-(K):
(A) trans-4,4′-azopyridine (B) 4,4′-azopyridine (C) bis (pyridyl) acetylene (D) 1,2-bis (4-pyridinyl) ethane (E) 4,4′- Bipyridine (F) 1,4-bis (4-pyridinyl) benzene (G) 4,2 ′: 5 ′, 4 ″ -terpyridine (H) 2,5-di-4-pyridinyl-pyrimidine (I) 3,6 -Di-4-pyridinyl-pyridazine (J) 2,5-di- (4-pyridinyl) pyrazine (K) Any selected from 3,6-di-4-pyridyl-1,2,4,5-tetrazine A proton conductive coordination polymer complex compound, characterized in that it is one kind.

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