Self-assembly of two 1D tube-like metal-organic networks based on flexible bis(benzimidazole) ligand and 5-nitroisophthalate

Two new polymeric networks, [Co(pbbm)(nip)] center dot H2O (1) and [Ni(pbbm)(nip) center dot (H2O)] (2) (pbbm = 1,1-(1,3-propanediyl)bis-1H-benzimidazole, H(2)nip = 5-nitroisophthalic acid) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 is an interesting one-dimensional (1D) tube-like chain utilizing [Co-2(pbbm)(2)] metallocycle as subunit. Complex 2 is also an interesting 1D tube-like chain based on [Ni-2(pbbm)(2)] loop subunit. In the title complexes, the pi-pi stacking and H-bonding interactions extend the 1D tube into 3D supramolecular framework, respectively. The structural differences between the title complexes indicate the importance of metal ions for the creation of molecular architectures. Furthermore, the luminescent properties of 1 and 2 were investigated.