Dicarboxylate-induced structural diversity of luminescent Zn-II/Cd-II coordination polymers derived from V-shaped bis-benzimidazole

Six new coordination polymers (CPs) based on the V-shaped 1,3-bis(benzimidazolyl)benzene (bbib) have been synthesized under solvothermal conditions: [Zn(bbib)(ip)](n) (1), {[Zn(bbib)(oba)]center dot solvents}(n) (2), {[Zn(bbib)(tp)]center dot DMF}(n) (3), [Cd(bbib)(ip)](n) (4), {[Cd(bbib)(oba)]H2O center dot solvents}(n) (5) and {[Cd(bbib)(tp)]center dot DMF}(n) (6) (ip = isophthalate, oba = 4,4'-oxybisbenzoate and tp = terephthalate). Complexes 1-3 display a plane minimal net, (4,4) sheet and a hexagonal plane net, respectively. The structures of 4-6 range from a 1D zigzag chain (4), 2D (4,4) sheet (5) to a 3D pillar-layer coordination framework with pcu alpha-Po topology (6). The structural transition from 1D to 3D among these complexes is realized with the aid of different auxiliary ligands. The results demonstrate that the conformations and coordination modes of dicarboxylate ligands make an impact on the structural diversity of Zn-II/Cd-II coordination polymers. To the best of our knowledge, the CPs based on the bbib ligand have been successfully prepared for the first time. Moreover, complex 2 is a good bifunctional chemosensor for the detection of both Fe3+ and MnO4- with the detection limits of 3.31 ppm and 8.81 ppm, respectively, indicating that 2 could be used as an efficient fluorescent sensor with high sensitivity and selectivity for Fe3+ and MnO4-.