ABSTRACT
Cobalt(III) polypyridyl complexes of the type [Co(bpy)2DMHBT]3+, [Co(dmb)2DMHBT]3+ and [Co(phen)2DMHBT]3+ (where DMHBT = 11,13-dimethyl-13H-4,5,9,11,14-hexa aza-benzo[b] triphenylene-10,12-dione; bpy = 2,2′-bipyridine; dmb = 4,4′-dimethyl-2,2′-bipyridine; phen = 1,10-phenanthroline) have been synthesized and fully characterized by elemental analysis, IR, UV-Visible spectra, 1H, 13C-NMR and Mass spectra. The results of absorption and emission titrations as well as thermal temperature and Viscosity measurement studies reveal that [Co(bpy)2DMHBT]3+, [Co(dmb)2DMHBT]3+, and [Co(phen)2DMHBT]3+ are moderate to strong binders of Calf Thymus DNA. An experimental result indicates that the three complexes can intercalate in to DNA base pairs. Under the identical conditions the super-coiled pBR 322 DNA photo-cleavage activities of these three cobalt(III) complexes follow the order:[Co(phen)2DMHBT]3+ > [Co(bpy)2DMHBT]3+ > [Co(dmb)2DMHBT]3+. These complexes are also found to have good antimicrobial activity.