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

•Pd(II) and Pt(II) complexes containing distal hydrogen-bonding sites are reported.•Hydrogen bonding and π-stacking interactions mediate complex assembly.•Many of the π-stacking interactions involve the chelate rings.•Hirshfeld surface analysis provides insight into complex assembly.

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.

Graphical abstract[PdCl2(L)] and [PtCl2(L)] complexes of ((2-pyridyl)pyrazol-1-ylmethyl)benzoic acids have been prepared and characterised. In the solid state molecules assemble via π(chelate)-stacking and a variety of hydrogen bonding motifs, the natures of which was also explored using Hirshfeld surface analysis and DFT calculations. Cytotoxicity studies on the [PtCl2(L)] complexes are also reported.Figure optionsDownload full-size imageDownload as PowerPoint slide