New dimeric and supramolecular mixed ligand Palladium(II) dithiocarbamates as potent DNA binders

Five Pd(II)-based potential potent metallopharmaceuticals (1-5) of the general formula [(DT)Pd(PR3)Cl], where DT = dibutyldithiocarbamate (1,2), dipropyldithiocarbamate (3), bis(2-methoxyethyl)-dithiocarbamate (4), dimethyldithiocarbamate (5): PR3 = triphenylphosphine (1), diphenyl-p-tolylphosphine (2), diphenyl-t-butylphosphine (3), diphenyl-2-methoxyphenylphosphine (4), p-cholorodiphenylphosphine (5), have been synthesized and characterized using FT-IR. Raman, and multinuclear-NMR spectroscopy. The X-ray single crystal analysis (1 and 2) reveals the Pd(II) moiety is in a distorted square-planar arrangement with two positions being occupied by the bidentate dithiocarbamate ligand, while the other two positions are occupied by a phosphine ligand and a chloro group. The packing diagrams confirmed that the intermolecular Cl center dot center dot center dot H interactions are not only the main cause of deviation from an ideal square planar geometry, but are also responsible for the Pd-S bond lengths variation. The DNA binding ability of the complexes was examined by cyclic voltammetry (CV). The cyclic voltammograms of the synthesized metallopharmaceuticals followed irreversible electrochemical behavior, which indicate the high reactivity of the reduced form of complexes. The results obtained from CV evidenced the catalytic role of DNA in enhancing the electron transfer processes of the complexes. The DNA binding studies are expected to provide useful insights about the unexplored mechanism by which anticancer drugs exert their biochemical action. (C) 2012 Elsevier Ltd. All rights reserved.