Construction of a series of Co(II)-based coordination polymers with boosted photocatalytic activity for the removal of dye contaminants

When symmetrical V-shaped rigid multicarboxylic acid, 3,5-di(2′,4′-dicarboxyphenyl)benzoic acid (ddb), was selected, five structurally coordination polymers (CPs) have been prepared, namely {[Co2(ddb)(dip)(NMP)(H2O)]·3H2O}n (1), {[Co2(ddb)(dpb)(H2O)]·NMP}n (2), {[Co2(ddb)(dib)(H2O)]·H2O}n (3), {[Co5(ddb)2(H2O)12]·4H2O}n (4) and {[Co3(ddb)(μ3-OH)(bpy)2]}n (5) (dip = 2,6-di(1H-imidazol-1-yl)pyridine; dib = 1,4-di(1H-imidazol-1-yl)benzene; bpy = 2,2′-bipyridine, dpb = 1,1′-(2,5-dimethyl-1,4-phenylene)bis(1H-imidazole) and NMP = N-Methyl-2-pyrrolidone). It was revealed that the flexible frameworks as well as different types of coordination environment of ddb were induced by the solvents and assistant linkers, single crystal X-ray crystallography, and thermogravimetric analysis (TGA), were used to characterize these coordination polymers. The photocatalytic degradation properties of all the structures are investigated against different dye like such as Rhodamine (RhB), methyl orange (MO), methylene blue (MB), methyl violet (MV). When compared to other dyes, the degradation efficiency of MV by 2 was quite high. Furthermore, a photodegradation process was proposed and investigated by radical tapping experiment. The Hirshfeld surfaces study demonstrated that these synthesized coordination polymers contain various forms of intermolecular contacts (C⋯C, H⋯C, H⋯H, and O⋯H).