Theoretical studies on the DNA-intercalator properties of Co(III) polypyridyl complexes

► The optimized-in-aqueous-solution geometry structures of complexes 1 and 2 were docked into DNA using the Dock6.0 program. ► The whole models (complex-DNA) were obtained. ► The trend in DNA-binding affinities of complexes was reasonably explained by the DNA-binding energies and strong H-bonds. ► The electronic absorption spectra of DNA-docking models were calculated and simulated using the TDDFT method. ► The intense absorption spectra measured experimentally of Co(Ш) complexes intercalating DNA can be explained in detail.