Microwave-assisted synthesis and evaluation of chalcone-ligated molybdenum carbonyl complexes as cytotoxic agents and DNA binders

Microwave irradiation of a mixture of Mo(CO)6 and pyridinecarboxaldehyde (pyca), acetylpyridine (acpy) and pyridyl-anthryl chalcones with tetrahydrofuran solvent in a closed vessel afforded products in good yields without the need for an inert atmosphere. While the reaction with 3- and 4-pyridyl moieties gave the cis- disubstituted complexes Mo(CO)4(L)2, the reaction with 2-pyridyl entities yielded complexes with a range of structures such as Mo(CO)2(L)2, Mo(CO)4L and Mo2(CO)6(L)2. All the novel complexes have been characterised by IR and 1H NMR spectroscopy as well as elemental analysis. In addition, the solid-state structure of one of the chalcone-ligated compounds has been determined by single-crystal X-ray diffraction. The chalcone-ligated complexes were found to be cytotoxic through the brine shrimp lethality assay, and were able to bind to quadruplex DNA. On the other hand, the pyca- and acpy-ligated compounds did not display any lethality and were unable to interact with DNA. The results indicate that the inclusion of a chalcone ligand plays an important role in improving the cytotoxicity and DNA binding capabilities of molybdenum carbonyl compounds.