Synthesis, X-ray crystal structure and cytotoxicity studies of lanthanide(III) iodide complexes with antipyrine

Isomorphous lanthanide(III) complexes of the composition [Ln(AP)6]I3, consisting of the octahedral complex cations [Ln(AP)6]3+ (Ln: La–Nd, Sm–Lu, AP: antipyrine, 2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) and iodide ions in the outer sphere, were prepared and characterized by single crystal X-ray diffraction, IR vibrational spectroscopy, thermal analysis and DFT calculations. Their cytotoxic activity was studied and compared with that of the ligand. It was demonstrated that the complexes, in some cases, are more cytotoxic than the ligand itself. The complexes crystallize in the trigonal crystal system (sp. gr. R3¯) and antipyrine molecules are coordinated to the metal atom via an oxygen atom of the ligand carbonyl group. The experimental results are confirmed by calculated ones. A comparison of the data obtained reveals trends in the changes of some properties with the increasing atomic number of the central atom.