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 [Mn2(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 {44·62} and CP 3 forms a 3D hexagon-shaped twofold interpenetrated sqc6 network with the point symbol {66}. 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.