Quantitative studies of DNA binding with trans complexes of PtII and PdII featuring tetrazolylacetic acids and their derivatives as ligands

Abstract

The interaction of calf thymus DNA (CT DNA) with trans-[PtCl₂L₂] and trans-[PdCl₂L₂] complexes (L–5-methyl-1H-tetrazol-1-ylacetic acid and its ethyl, butyl, and isobutyl esters; ethyl esters of 2-R-2H-tetrazol-5-ylacetic acids, R = Bu^t, CH₂CH₂OH) have been quantitatively studied by a spectrophotometric method. The binding constants (K_b) of the tetrazolecontaining coordination compounds with CT DNA at pH 7.2 and 298 K are in the range of (3.67–5.93)•10⁵ mol L^–1 for the Pd^II complexes and (7.82–13.30)•10⁵ mol L^–1 for and the Pt^II complexes, respectively. The K_b values, as well as negative values of ΔG_b (–(31.7–34.9) kJ mol^–1) indicate the effective binding between the studied complexes and CT DNA.