Palladium(II) and platinum(II) complexes of ((2-pyridyl)pyrazol-1-ylmethyl)benzoic acids: Synthesis, Solid state characterisation and biological cytotoxicity

The new ligands 3-(3-(2-pyridyl)pyrazol-1-ylmethyl)benzoic acid (L2) and 5-(3-(2-pyridyl)pyrazol-1-ylmethyl)benzene 1,3-dicarboxylic acid (L3) are reported and the synthesis and characterisation of [PdCl₂(L)] and [PtCl₂(L)] complexes of these and the previously reported 4-(3-(2-pyridyl)pyrazol-1-ylmethyl)benzoic acid (L1) are described. In the solid state, the square planar complexes assemble via hydrogen bonding interactions involving COOH and M-Cl groups as well as by various π-stacking interactions involving the aromatic rings on the ligands and, notably, the chelate rings. Hirshfeld surface analysis has been used to gain insight into the assembly of the molecules. Preliminary studies of the biological cytotoxicity of the [PtCl₂(L)] complexes against A549 and MDA-MB-231 cancer cell lines are reported.