Multidimensional networks constructed with 2,5-dichloroterephthalate and bis(benzimidazole) co-ligands: Syntheses, structures, electrochemical and photocatalytic properties

A halogenated linear bridged dicarboxylic acid ligand, 2,5-dichloroterephthalic acid (H2DCTP), was used to construct three coordination polymers (CPs) with Mn(II) salts in the presence of different bis(benzimidazole) N-containing co-ligands: 1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene (L1), 1,4-bis(5,6-dimethylbenzimidazole)butane (L2) and 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene (L3). The products formed under solvothermal conditions are formulated as [Mn(DCTP)(L1)(2).(H2O)(2)](n) (1), [Mn(DCTP)(L2).(H2O)(2)](n) (2) and [Mn-2(DCTP)(2)(L3)(3)](n) (3). These CPs were characterized by elemental analysis, single-crystal X-ray diffraction analysis, infrared spectra (IR), thermogravimetric analyses (TGA) and powder X-ray diffraction (PXRD). CP 1 exhibits a 1D wave-like chain, while CP 2 is a 2D sql layer with the point symbol {4(4).6(2)} and CP 3 forms a 3D hexagon-shaped twofold interpenetrated sqc6 network with the point symbol {6(6)}. These results indicate that the flexible bis(benzimidazole) co-ligands have a significant effect on the dimensionality of the resulting coordination framework. CPs 1-3 exhibited relatively high photocatalytic activities towards the degradation of methylene blue (MB) and methyl orange (MO) in aqueous solution under UV irradiation. Moreover, the luminescence and electrochemical properties of 1-3 were also investigated. (C) 2017 Elsevier Ltd. All rights reserved.