Palladium(II) and Platinum(II) Complexes Containing Six-Membered N-Heterocyclic Ligands: Synthesis, Characterization, Interaction with DNA, DFT Calculation, and Cytotoxicity.

Four novel complexes based on the ligand piperazine (Pip) in a chair conformation have been synthesized, namely [Pd(5,5′-dcbpy)Pip] ·4H2O ( 1), [Pt(5,5′-dcbpy)Pip] ·3H2O ( 2), [Pd(4,4′-dcbpy)Pip] ·4H2O ( 3), and [Pt(4,4′-dcbpy)Pip] ·2H2O ( 4; 4,4′-dcbpy = 2,2′-bipyridyl-4,4′-dicarboxylate, 5,5′-dcbpy = 2,2′-bipyridyl-5,5′-dicarboxylate). The four complexes were characterized by elemental analysis, FTIR spectroscopy, 1H and 13C NMR spectroscopy, and single-crystal X-ray diffraction analysis. In addition, gel electrophoresis was performed on the four complexes and further insight into these complexes was gained by quantum chemistry calculations. The interaction of these complexes with fish sperm DNA (FS-DNA) was studied by UV/Vis and fluorescence spectroscopy, which revealed that they have the ability to bind to FS-DNA. The IC50 values of the four complexes range from 8.3 to 32.5 μ M. Finally, we studied the cytotoxic activities of complexes 1- 4 against two different cancer cell lines. [ABSTRACT FROM AUTHOR]