Crystal structures, bioactivities and fluorescent properties of four diverse complexes with a new symmetric benzimidazolic ligand

Abstract: A new ligand, pyridine-3,5-bis(benzimidazole-2-yl) (pbb), and four complexes containing pbb, namely [pbb(Hpbb)2]SO4 ·7H2O (1), [Zn(pbb)2(H2O)4](NO3)2 ·2C2H5OH·4H2O (2), [Cd(pbb)2(H2O)4](NO3)2 ·2C2H5OH·4H2O (3) and [Zn2(pbb)2(μ-OH)(μ-OAc)](OAc)2 ·7H2O (4) (HOAc=acetic acid), have been designed, synthesized and characterized. Complexes 1–4 show 3D supramolecular architectures that are connected through hydrogen bonds and aromatic π–π interactions. A self-assembled (H2O)12 cluster with a chair conformation (H2O)6 ring core is observed in 1, which exhibits an unusual association mode of water molecules. Compounds 2 and 3 present 3D supramolecular structures involving 1D open channels encapsulating ions, and crown-like rings are found in 4. In addition, the preliminary antibacterial activity of pbb and its complexes were investigated by two methods, which indicate a selective inhibition property for the tested strains. Strong emissions from the complexes were also changed by the coordination modes in the sold state. [Copyright &y& Elsevier]