Antimicrobial and nuclease activity of mixed polypyridyl ruthenium(II) complexes

The ruthenium(II) complexes with 2,9-dimethyl-1,10-phenanthroline (dmphen) and terpyridine derivatives have been synthesized and screened for their antimicrobial potency. The interaction of these complexes with Herring Sperm DNA was investigated by thermal denaturation, viscosity measurements, gel electrophoresis and spectrophotometric methods. The results indicate that the complexes bound to DNA via partial intercalative mode. The salt-dependent binding of these complexes has been determined by UV–Vis spectrophotometric titration. The contribution of the non-electrostatic binding free energy (ΔG_t^o) to the total binding free energy change (ΔG^o) is found to be ~ 88% at [Na⁺] = 0.075 M. The large value suggests that the stabilization of the DNA binding is mostly due to the contribution of non-electrostatic process.