New metallic compounds with ligands derived from Hpyrimol. Study of their interaction with DNA

Abstract

The new ligands (E)-4-(((pyridine-2-ylmethyl)imino)methyl)aniline (L1) and (E)-2-(((5-bromopyridin-2-yl)methylene)amino)phenol (L2OH) have been prepared by the condensation of 4-aminobenzaldehyde and 2-pycolylamine or 5-bromopycolynaldehyde and 2-aminophenol respectively. The reaction of L1 with Na2PdCl4 produce a mixture of the compounds [PdCl2(L1)] and [PdCl2(2-pycolylamine)], this last one due to the ligand hydrolysis. The presence of a phenolic ring with a hydroxyl group susceptible to be deprotonated in ligand L2OH causes that the reaction of this ligand with Na2PdCl4 or [PtCl2(DMSO)2] produce a mixture of the compounds [MCl(L2O)] and [MCl2(L2OH)], {M = Pd(II), Pt(II)}. The ligand L2OH acts as a (N,N’,O) tridentate donor group in the former one compound or as a (N,N’) bidentate ligand in the second one. Modifying the pH it is possible to obtain pure compounds, but the [MCl2(L2OH)] complexes synthesized are very unstable in solution. The ligands and the metallic compounds were characterized by elemental analysis, infrared spectroscopy (IR) and mono- and two-dimensional NMR spectroscopies. It was also possible to determinate the crystalline structure of L2OH by X-ray diffraction. The interaction with DNA was studied for [MCl(L2O)] {M = Pd(II), Pt(II)} and [PtCl2(L2OH)] complexes by UV-Vis and fluorescence spectroscopies, circular dichroism and electrophoresis. The complexes that, in general, present more interaction with DNA are [PdCl(L2O) and [PtCl2(L2OH)]]