Schiff base ligands were synthesized by condensation of 5-amino-1,10-phenanthroline with 4-
hydroxybenzaldehyde (L1) and decanal (L2). Ruthenium (II) metal complexes (L1-Ru(II), L2-Ru(II)) were
prepared in good yield from the reaction of the ligands with the bis(2,2
dichloride. Structures of synthesized compounds were characterized using elemental analyze, FTIR, UVVisible, 1H NMR and mass spectra. The DNA-binding properties of the ligands and complexes with calf
thymus DNA was investigated by spectroscopic, gel electrophoresis and viscosity measurement.
The interaction of the ligands and ruthenium complexes with calf tymus DNA (CT-DNA) have been
demonstrated using electronic absorption titration method. Based on the UV–Vis spectroscopy, binding
constants of the synthesized compounds with CT-DNA calculated. From the results, it is observed that
L1 and L1-Ru(II) bind to CT-DNA via groove binding and electrostatic mode and L2 and L2-Ru(II) bind to
CT-DNA via intercalation. Kb values of L1 and L1-Ru(II) with CT-DNA were calculated as 5.2 × 105 M−1
and 4.8 × 106 M−1, respectively. Absorption spectral study indicated that L2 and L2-Ru(II) have intrinsic
binding constant (Kb) in the range of 3.8 × 105 -3.7 × 106 M−1. The results show that the complexes
have more binding ability than the ligands.