Quantitative studies of DNA binding with trans complexes of Pt II and Pd II featuring tetrazolylacetic acids and their derivatives as ligands

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 = But, CH2CH2OH) have been quantitatively studied by a spectrophotometric method. The binding constants (Kb) 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 PdII complexes and (7.82–13.30)•105 mol L–1 for and the PtII complexes, respectively. The Kb values, as well as negative values of ΔGb (–(31.7–34.9) kJ mol–1) indicate the effective binding between the studied complexes and CT DNA.