Low-dimensional compounds containing bioactive ligands. V: Synthesis and characterization of novel anticancer Pd(II)...

Three novel palladium(II) complexes, NH2(CH3)2[PdCl2(CQ)] (1) (CQ=5-chloro-7-iodo-quinolin-8-ol), NH2(CH3)2[PdCl2(dClQ)] (2) (dClQ=5,7-dichloro-quinolin-8-ol) and NH2(CH3)2[PdCl2(dBrQ)] (3) (dBrQ=5,7-dibromo-quinolin-8-ol) have been prepared and characterized. Their structures contain square-planar [PdCl2(XQ)](-) complex anions in which deprotonated XQ ligands are coordinated to the Pd atoms via the pyridine nitrogen and the phenolato oxygen atoms, other two cis-positions are occupied by two chlorido ligands. Negative charges of these anions are balanced by uncoordinated dimethylammonium cations. Coordination of the XQ ligands to Pd(II) atom was confirmed by the differences in the stretching ν(OH) and ν(CN) vibrations in the IR spectra of ligands and prepared complexes while bands of aliphatic CH and NH stretching vibrations observed in the spectra of 1-3 confirm the presence of dimethylammonium cations in the complexes. The binding of complexes 1-3 to calf thymus DNA was investigated using UV-visible and fluorescence emission spectrophotometry. The fluorescence spectral results indicate that the complexes can bind to DNA through an intercalative mode. The Stern-Volmer quenching constants obtained from the linear quenching plot are in the 1.04 × 10(4) to 4.35 × 10(4) M(-1) range. The complexes exhibit significant anticancer activity tested on A2780 cells and cisplatin resistant cell line A2780/CP.