Abstract Four new complexes of platinum(II) and palladium(II) with planar tridentate ligands, 2,6-bis(N-H-benzimidazol-2-yl)pyridine (L-H), and 2,6-bis(N-methyl-benzimidazol-2-yl)pyridine (L-Me), as [Pt(L-H)Cl]Cl (1), [Pd(L-H)Cl]Cl (2), [Pt(L-Me)Cl]Cl (3), and [Pd(L-Me)Cl]Cl (4) have been synthesized and fully characterized by means of CHN, FT-IR (ATR), 1H NMR, and ESI or MALDI TOF MS techniques. The DNA-binding behaviors of all complexes have been investigated by absorption titration, EtBr displacement measurement, and gel electrophoresis and viscosity measurement studies.
The results showed that complexes 1–4 can bind to DNA via partial intercalation mode. The metal complexes of L-Me, 3 and 4 are more hydrophobic, and thus showed better binding ability to DNA’s hydrophobic environment, as revealed by the intrinsic binding constants Kb for 1–4 as being 4.76 (± 0.6) x 104 M-1, 5.01 (± 0.9) x 104 M-1, 2.50 (± 0.6) x 105 M-1 and 2.25 (± 0.9) x 105 M-1, respectively. In addition, 3 and 4 are efficient cleavers of plasmid DNA.