Effect of solvent on the construction of Co(II) coordination polymers containing a semi-rigid bis(benzimidazole) derivative: syntheses, structures, and properties.

Two Co(II) coordination polymers, [CoL(npa)]·2H2O (1) and [CoL(Hnpa)2] (2) (L = 1,4-bis(5,6-dimethylbenzimidazole-1-yl)benzene, H2npa = 5-nitroisophthalic acid), have been synthesized in different solvent systems and characterized by Infrared (IR) spectroscopy, elemental analysis, and powder and single crystal X-ray diffraction. Compound1was synthesized under solvothermal conditions with DMF as solvent and had a pair of L ligands adopting aμ2-bridging mode and connecting two Co2+cations to generate a 26-membered Co2L2loop. The npa2−link adjacent Co2L2loops via a bis(monodentate) bridging mode to create a 1-D channel-like chain structure. Compound2was obtained under hydrothermal conditions, and the carboxylate of the monodeprotonated Hnpa−adopt aμ1-η0 : η1coordination to connect adjacent Co2+cations into a 2-D polymeric layer. Theμ2-bridging L ligands connect adjacent 2-D [Co(Hnpa)]npolymeric layers into a 3-D NaCl-like framework. The Co2+cations and the L ligands in compounds1and2exhibit different coordination geometries and conformations. Effects of solvents on the construction of Co(II) coordination polymers were investigated. In addition, the electrochemical behavior of carbon paste electrodes containing1and2and the thermal stabilities of1and2were investigated. [ABSTRACT FROM PUBLISHER]