Synthesis and characterization of three cobalt(II) coordination polymers with tetrabromoterephthalic acid and flexible bis(benzimidazole) ligands

Abstract

Three cobalt(II) coordination polymers, namely {[Co(tbta)(pbdmbm)]·0.5H2O} n (1), [Co(tbta)(bbdmbm) (H2O)2] n (2), and [Co(tbta)(bbbm)] n (3), have been hydrothermally synthesized by self-assembly of cobalt(II) nitrate with tetrabromoterephthalic acid (H2tbta) and three flexible bis(benzimidazole) ligands, respectively, 1,1′-(1,4-butanediyl)bis-1H-benzimidazole (bbbm), 1,1′-(1,3-propanediyl)bis(5,6-dimethylbenzimidazole) (pbdmbm), and 1,1′-(1,4-butanediyl)bis(5,6-dimethylbenzimidazole) (bbdmbm). Single-crystal X-ray diffraction analysis reveals that complex 1 has a 1D ladder-like chain structure, while both complexes 2 and 3 feature a uninodal 2D (4, 4) layer structure with a {44.62}-sql topology. Additionally, the fluorescence properties and catalytic activities of the complexes for degradation of congo red by a Fenton-like process were investigated.