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

Abstract A halogenated linear bridged dicarboxylic acid ligand, 2,5-dichloroterephthalic acid (H 2 DCTP), 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 ·(H 2 O) 2 ] n ( 1 ), [Mn(DCTP)(L2)·(H 2 O) 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.