Photocatalytic properties of two Co(II) coordination polymers with tri(2-methylimidazole) and multicarboxylate

Two new Co(II) coordination polymers show (3,3)-connected 1D ladder chain and (4,4)-connected 2D topology, and good photocatalytic activities for degradation of methylene blue and methyl violet. [Display omitted] Two new coordination polymers with the formula {[Co2(tmpa)2(tdc)2(H2O)4]·H2O}n (1) and {[Co2(tmpa)2(btec)]·DMF·H2O}n (2) (tmpa = tris(4-(2-methyl-1H-imidazol-1-yl)phenyl)amine, tdc2− = 2,5-thiophenedicarboxylicate, btec4− = 1,2,4,5-benzenetetracarboxylicate) were obtained under hydrothermal conditions and characterized by PXRD, UV–vis DRS and SEM. 1 has (3,3)-connected 1D ladder chains, which further extend into a (3,5)-connected 2D supramolecular framework built byOH···O hydrogen-bonding interactions. 2 exhibits (4,4)-connected 2D networks showing point symbol (42·64)(4·64·8). 1 and 2 both displayed high photocatalytic activities for the decomposition of methylene blue (MB) and methyl violet (MV). 1 and 2 can degrade 87.2% and 91.7% MB, respectively, in 75 min under visible light irradiation. 1 and 2 could degrade 82.2% and 91.8% MV, respectively, in 105 min under visible light irradiation. Therefore, 2 possessed better photocatalytic performance. The trapping experiments and ESR test indicated that O2– was the primary species in the process of MB degradation of 1 and 2. In addition, Hirshfeld surface analysis was also adopted to further address the probable mechanistic pathway.