Synthesis, structures and electrochemical properties of two novel metal–organic coordination complexes based on trimesic acid (H3BTC) and 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (BPO)

Two novel metal–organic coordination complexes [Cu(HBTC)(BPO)]·H2O (1) and [Co3(BTC)2(BPO)3(H2O)2]·5.25H2O (2), have been synthesized from hydrothermal reaction of metal chloride with the mixed ligands 1,3,5-benzenetricarboxylate (H3BTC) and bent dipyridyl based ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (BPO), and structurally characterized by elemental analyses, IR, TG and single-crystal X-ray diffraction analysis. The results reveal that each dinuclear CuII unit is bridged by two kinds of different ligands (H3BTC and BPO) to form one-dimensional (1-D) chain structure in complex 1. The adjacent chains for 1 are further linked by π–π stacking interactions and hydrogen bonding interactions to form a three-dimensional (3-D) supramolecular framework. Complex 2 possesses a 3-D network composed of three different cobalt(II) centers [carboxylate-bridged dinuclear cobalt units and mononuclear cobalt ion] and bridging ligands BTC and BPO, which presents the first example of 3-D coordination polymer constructed from the BPO ligands simultaneously showing three different coordination modes. Moreover, the electrochemical behaviors of the two complexes bulk-modified carbon paste electrodes (1-CPE and 2-CPE) have been reported.

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