Palladium(II) 4,5-Diphenylimidazole Cyclometalated Complexes: DNA Interaction

✍ Scribed by Félix Zamora; Víctor M. González; José M. Pérez; José R. Masaguer; Carlos Alonso; Carmen Navarro-Ranninger

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 182 KB
• Volume: 11
• Category: Article
• ISSN: 0268-2605
• DOI: 10.1002/(sici)1099-0739(199706)11:6<491::aid-aoc602>3.0.co;2-f

✦ Synopsis

In this paper, we show the synthesis of palladium(II) 4,5-phenylimidazole cyclometalated complexes. They have been characterized by IR, 1 H-and 13 C-NMR spectroscopy. The cyclometalated dimer compound 2 [Pd(C 15 H 11 N 2 )(-OAc)] 2 and the cyclometalated monomer compound 5 [PdBr(SEt 2 )(C 15 H 11 N 2 )], having OAc and Br as leaving groups, interact with DNA, modifying its secondary structure (as measured by T m and CD), without modifying its tertiary structure (as determined by measurement of the electrophoretic mobility in agarose gels). The monomeric compound 5 seems to be the one that induces the highest alterations in DNA secondary structure since it strongly modifies the CD spectrum of the DNA. Melting data of drug-DNA complexes suggest that, at low drug concentration, the 4,5-Imd ligand intercalates between the base pairs in the DNA molecule, increasing the T m , while at high drug concentrations the palladium(II) centers destabilize the double helix, producing a lowering in T m values. These results indicate that complexes containing planar structures might selectively bind to DNA that is not supercoiled, and that therefore it only has a secondary structure.