Temperature-Controlled Structure Diversity Observed in a Copper Pyridine-2,6-Dicarboxylate System

Abstract

Three polymorphic complexes, namely [Cu₂(pdc)₂(bpe)₂(H₂ O)₂]·H₂O (1), [Cu₂(pdc)₂(bpe)₂(H₂O)₂]·H₂O (2), and {[Cu₂(pdc)₂ (bpe)₂(H₂O)]·3H₂O}_n (3) (bpe = 1,2-bis(4-pyridyl)ethylene), were synthesized via in situ ligand transformation reaction, in which 1,2-bis(4-pyridyl)ethane (bpa) undergoes dehydrogenation to 1,2-bis(4-pyridyl)ethylene (bpe), which was found to be highly dependent on the reaction temperature. Polymorphs 1 and 2 have the same molecular formula but distinct differences in morphology, triclinic system with P _ī space group, and monoclinic system with C2/c space group, respectively. Structural comparison shows that complexes 1 and 2 consist of centrosymmetric binuclear building blocks, while complex 3 features a one-dimensional (1-D) ladder chain. The thermal properties were also investigated for the complexes.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry to view the supplemental file.

Keywords:

• 1,2-bis(4-pyridyl)ethane
• in situ reaction
• polymorph
• pyridine-2,6-dicarboxylic acid

Acknowledgments

The authors are grateful to the Natural Science Foundation of Henan Province (No. 112300410138), the Foundation of the Education Department of Henan Province (No. 2011B150021), and the Applied Foundation (No. 10000992) of Luoyang Normal University for the financial support.