Palladium(II) Complexes with Noncovalent Interactions with DNA: Solution Speciation Controlled by Solvent Identity, pH, and Concentration

The coordination capacity of thiosemicarbazone ligands and their synergism with palladium(II) ions modulate their reactivity, allowing custom design. Using thiosemicarbazones with two potential stable tautomeric forms and imidazole as bioisosteres, we studied how the substitution in the N4 group of the thiosemicarbazone by the <i>p</i>-chlorophenyl group modifies their hydrophilic properties, integrity in solution, and interactions toward their potential targets. The coordination to Pd(II) affects the bioactivity of the ligands, resulting in either improved or reduced antiproliferative effects depending on the cell type (cancerous versus bacterial, respectively).