Synthesis, Characterization, DNA-Binding, and DNA-Photocleavage Properties of [Co(bpy)₂(7-NO₂-dppz)]³⁺, [Co(dmb)₂(7-NO₂-dppz)]³⁺, and [Co(phen)₂(7-NO₂-dppz)]³⁺Complexes: (7-Nitro-dppz = 7-Nitro dipyrido[3,2-a:2′-3′-c]phenazine; bpy = 2,2′-bipyridine; dmb = 4,4′-dimethyl-2,2′-bipyridine; phen = 1,10-phenanthroline) and their Toxicity on Different Microorganisms

The polypyridyl ligand 7-Nitro dipyrido[3,2-a:2'-3'-c]phenazine (7-Nitro-dppz) and its complexes [Co(bpy)(2)(7-NO(2)-dppz)](3+)(1) (bpy = 2,2'-bipyridine), [Co(dmb)(2)(7-NO(2)-dppz)](3+)(2), (dmb = 4,4'-dimethyl-2,2'-bipyridine), and [Co(phen)(2)(7-NO(2)-dppz)](3+)(3) (phen = 1,10-phenanthroline) were synthesized and characterized by UV/VIS, IR, elemental analysis, (1)H and (13)C-NMR, and mass spectra. The binding properties of the three complexes to CT-DNA were investigated by different spectroscopic methods and viscosity measurements and DNA cleavage assay. The experimental results suggest that these complexes bind to CT-DNA through an intercalative mode. Also, the three complexes promote the photocleavage of plasmid pBR-322 DNA under irradiation. Toxicological effects of the selected complexes were estimated with different microorganisms.