Synthesis, Supramolecular Architecture and DNA Binding Studies of a Novel Heterotrinuclear FeIII/CoII/FeIII Complex: [Co(phen)2][Fe(phen)(CN)4]2•4H2O (phen=1,10-phenanthroline)

A novel cyano-bridged heterotrinuclear Fe-III/Co-II/Fe-III complex, [Co(phen)(2)][Fe(phen)(CN)(4)](2)center dot 4H(2)O (1) (phen = 1,10-phenanthroline), has been synthesized under solvothermal conditions, and characterized by elemental analysis, FI-IR spectrum and single-crystal X-ray diffraction. The structure analysis reveals complex 1 is constructed into a 3D supramolecular architecture through abundant intermolecular non-covalent interactions. According to the supramolecular self-assembly of complex 1, five types of pi-pi stacking models of phenanthroline ligands, hydrogen bonds formed by four lattice water molecules, and C-H center dot center dot center dot N weak interactions involving cyano groups are all observed. Electronic absorption spectroscopy and fluorescence titration studies of the interaction between complex 1 and calf thymus DNA are suggestive of an intercalative binding mode with an intrinsic binding constant of 7.95 x 10(3) M-1 and a linear Stern-Volmer quenching constant of 1.033 x 10(5) M-1.