Synthesis,characterization, and DNA-binding of [Co(phen)2(CPIA)]3+, [Co(phen)2(BIP)]3+, and [Co(phen)2(CIP)]3+

Three ligands, 2-(3-(carboxymethyl)-1,10-phenanthroline-5,6-d]imidazole-1-yl)acetate (CPIA), 2-(benzod]1,3]dioxol-4-yl)-1H-imidazo4,5-f]1,10]phenanthroline (BIP), and 2-(9H-carbazol-3-yl)-1H-imidazo4,5-f]1,10]phenanthroline (CIP), and their complexes, Co(phen)₂(CPIA)]³⁺ (1) (phen = 1,10-phenanthroline), Co(phen)₂(BIP)]³⁺ (2), and Co(phen)₂(CIP)]³⁺ (3), have been synthesized and characterized. Binding of the three complexes with calf thymus DNA (CT-DNA) has been investigated by spectroscopic methods, cyclic voltammetry, and viscosity measurements. The three complexes bind to DNA through an intercalative mode, and the size and shape of the intercalative ligands have significant effects on the binding affinity of complexes to CT-DNA.