Syntheses, crystal structures, and electrochemical properties of two cobalt complexes constructed with benzene tricarboxylates and 2,5-bipyridyl-1,3,4-oxadiazole

Abstract

Two new cobalt complexes based on benzene tricarboxylates 1,2,4-H₃BTC (1,2,4-H₃BTC = 1,2,4-benzenetricarboxylate) or 1,3,5-H₃BTC (1,3,5-H₃BTC = 1,3,5-benzenetricarboxylate), and the bent dipyridyl ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) or its 4-pyridyl N-donor analog (4-bpo), formulated as [Co(1,3,5-BTC)(4-bpo)(H₂O)₃]₂[Co(H₂O)₆] · 10H₂O (1) and [Co₃(1,2,4-BTC)₂(3-bpo)₂(H₂O)₁₂] (2), have been hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, TG analyses, and single-crystal X-ray diffraction. Structure analysis reveals that 1 is a 3-D porous supramolecular network based on the 1-D polymer chain , in which discrete [Co(H₂O)₆]²⁺ units and lattice water molecules are dispersed. In 2, bridging 3-bpo and 1,2,4-BTC connect cobaltions to form a trinuclear cobalt unit. Adjacent trinuclear cobalt units are further linked by π–π stacking interactions and hydrogen-bonding interactions to form a 3-D supramolecular framework. Electrochemical properties of cobalt(II) compounds bulk-modified carbon paste electrodes (1-CPE and 2-CPE) have been studied.

Keywords:

• Cobalt compounds
• Hydrothermal syntheses
• Crystal structures
• Electrochemical properties

Acknowledgments

This work was supported by the National Natural Science Foundation of China (No. 20871022) and the Education Office Foundation of Liaoning Province (Nos 2009R03 and 2009402007).