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

A new ligand, pyridine-3,5-bis(benzimidazole-2-yl) (pbb), and four complexes containing pbb, namely [pbb(Hpbb)(2)]SO4 center dot 7H(2)o (1), [Zn(pbb)(2)(H2O)(4)](NO3)(2) center dot 2C(2)H(5)OH center dot 4H(2)O (2), [Cd(pbb)(2)(H2O)(4)](NO3)(2)center dot 2C(2)H(5)OH center dot 4H(2)O (3) and [Zn-2(pbb)(2)([L-OH)(mu-CAc)](OAc)(2)center dot 7H(2)O (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 pi-pi 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 I D open channels encapsulating NO3- 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. (C) 2008 Elsevier Ltd. All rights reserved.