Metal(II) Ion Dependence of the Structures and Properties of Square-Grid Coordination Polymers of Tetrabromobenzenedicarboxylate and Pyrazine as Bridging Ligands

In this study, we report the synthesis and crystal structures of coordination polymers employing tetrabromobenzenedicarboxylate (Br4bdc2−) and pyrazine (pyz). Uncoordinated pyz molecules are stabilized between the layers by both hydrogen H-bonding and π–π stacking interactions in [M(Br4bdc)(pyz)(H2O...

Full description

Saved in:
Bibliographic Details
Published in:Bulletin of the Chemical Society of Japan 2021-05, Vol.94 (5), p.1571-1578
Main Authors: Kumagai, Hitoshi, Setoyama, Norihiko, Kawata, Satoshi, Sakamoto, Yoshiyuki
Format: Article
Language:English
Subjects:
Chemical synthesis
Cobalt
Coordination polymers
Crystal structure
Crystallinity
Dehydration
Heating
Jahn-Teller effect
Proton conduction
Relative humidity
Stacking
Water chemistry
Zinc
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:In this study, we report the synthesis and crystal structures of coordination polymers employing tetrabromobenzenedicarboxylate (Br4bdc2−) and pyrazine (pyz). Uncoordinated pyz molecules are stabilized between the layers by both hydrogen H-bonding and π–π stacking interactions in [M(Br4bdc)(pyz)(H2O)2](pyz), where M = Co(II) and Zn(II). In addition, water molecules are incorporated between the layers in [Cu(Br4bdc)(pyz)(H2O)2](H2O) owing to Jahn–Teller distortion of the Cu(II) ions, which prevents π–π stacking interactions between the pyz and Br4bdc2−. Depending on the metal(II) centers, structural changes that occur during the heating and hydration processes exhibit different behavior. Co(II) compound slowly changes structure by heating and rapidly recovers the crystalline state in air. Conversely, Zn(II) compound assumes the amorphous phase by heating and slowly yields the crystalline phase in ambient conditions. Although the Cu(II) compound also shows structural changes by heating, the dehydrated phase exhibits hydrophobic characteristics. Ion conductivity measurements of the as-synthesized forms show conductivities of 1.9 × 10−6 Scm−1, 4.6 × 10−7 Scm−1, and 1.3 × 10−6 Scm−1, for the Co(II), Zn(II), and Cu(II) complexes at 90 °C and 95% relative humidity (RH), respectively. The relatively low values of the as-synthesized Co(II) and Zn(II) compounds are attributed to the H-bonding interaction and π–π stacking of pyz molecules, which prevent the dynamics of the pyz molecules needed for proton conduction.
ISSN:0009-2673
1348-0634
DOI:10.1246/bcsj.20210042