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Two pseudo-polymorphic copper-benzene-1,2,4,5-tetracarboxylate complexes.

Jian Hai Luo¹, Chang Cang Huang, Xi He Huang

¹Department of Chemistry, Fuzhou University, Fuzhou, Fujian, People's Republic of China.

Acta Crystallographica. Section C, Crystal Structure Communications

|June 7, 2007

Summary

This study details two pseudo-polymorphic copper-based polymers with distinct copper coordination environments. Hydrogen bonding in these polymers forms complex three-dimensional supramolecular structures.

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Area of Science:

Coordination Chemistry
Materials Science
Crystallography

Background:

Pseudo-polymorphism in metal-organic frameworks (MOFs) is crucial for tuning material properties.
Copper(II) complexes with benzene-1,2,4,5-tetracarboxylate (btc) ligands offer diverse structural possibilities.
Understanding the role of counter-ions and solvent molecules in MOF assembly is essential.

Purpose of the Study:

To synthesize and characterize two novel pseudo-polymorphic copper-based polymers.
To investigate the structural differences in copper coordination environments.
To elucidate the role of hydrogen bonding in forming 3D supramolecular architectures.

Main Methods:

Single-crystal X-ray diffraction for structural determination.
Analysis of coordination geometries and hydrogen bonding networks.
Comparison of crystallographic data for pseudo-polymorphic variants.

Main Results:

Two pseudo-polymorphic polymers, (I) and (II), were synthesized, featuring 2D anionic layers with ethylenediammonium cations and water molecules.
Polymer (I) exhibits a square-pyramidal Cu(II) coordination, while polymer (II) shows a square-planar Cu(II) coordination.
Both structures display extensive hydrogen bonding, leading to the formation of 3D supramolecular networks.

Conclusions:

The study highlights how subtle changes in coordination environment can lead to pseudo-polymorphism in copper-organic frameworks.
Ethylenediammonium cations and water molecules play a significant role in stabilizing the crystal structures through hydrogen bonding.
The formation of 3D supramolecular structures from 2D layers demonstrates the complexity achievable in coordination polymer design.