Aromatic carboxylic acid effect on the architectures of Co(II) coordination polymers based on a flexible double imidazole derivative

Two new Co(II) coordination polymers, namely, [Co(BBA)₂(L)] (I) and [Co(NIPA)(L)] (II) have been obtained from hydrothermal reactions of Co(II) chloride with two kinds of aromatic carboxylic acids: 4-bromobenzoic acid (HBBA), 5-nitroisophthalic acid (H₂NIPA), and a flexible double imidazole derivative 1,1′-(1,3-propanediyl)bis(5,6-dimethylbenzimidazole) (L). Single-crystal X-ray diffraction analysis reveals that compound I is 1D “zigzag” coordination polymer constructed by [Co(BBA)₂] subunits and L linkers. Compound II exhibits 2D (4,4) network based on double nuclear [Co₂N₄O₈] units and (L)₂/(NIPA)₂ double linkers. The different organic carboxylic acids influence on the coordination modes of metal ions and conformations of L ligands and thus determine the final structures of the title compounds. In addition, photoluminescence properties of the title compounds and the cyclic voltammetry behavior of compound II as a modified carbon paste electrode were investigated in this paper.