Three coordination polymers of 5-aminoisophthalic acid with similar benzimidazole derivative ligands: Synthesis, structure and DNA-binding studies

摘要

Three novel coordination polymers, [Co(NH _2-Aip)(H2Bibim)] _n(1), [Co(NH _2-Aip)(HBibimop)] n _nH _2O (2) and [Mn(NH _2-Aip)H _2O] _n 2nH _2O (3) with NH _2-Aip and similar benzimidazole derivative ligands (NH _2-Aip=5-aminoisophthalic acid, H _2 Bibim=2,2-bibenzimidazole and HBibimop=1,3-bis(benzimidazol-2-yl)-2-oxapropane), have been synthesised under hydrothermal conditions and structurally characterised by single-crystal X-ray diffraction analysis, elemental analysis and IR spectroscopy. 5-Aminoisophthalic acid ligand adopts μ _2-, μ _3-and μ _4-bridge coordination fashion and benzimidazole derivatives exist as terminal-and bridge-mode in complexes 1-3. The intricate hydrogen bonds and π-π stacking interactions in supramolecular framework are discussed. Using the combination of ultraviolet-visible absorption titration and fluorescence spectra, the experimental results show that complexes 1 and 2 bind to DNA in an intercalative mode and their DNA-binding constants (K _b) are also found.