Zinc(II) and cadmium(II) halide complexes with caffeine: Synthesis, X-ray crystal structure, cytotoxicity and genotoxicity studies

Abstract Molecular complexes [Zn(caf)(H 2 O)I 2 ] ( I ), [Zn(caf)(H 2 O)Cl 2 ] ( IV ), and the polymeric ones {[Cd(H 2 O) 2 I 2 ](caf) . 2H 2 O} n ( II ) and {[Cd(H 2 O) 2 Br 2 ](caf) . 2H 2 O} n ( III ) consisting of infinite Cd-containing chains with bridging halide ions and water molecules in trans -position and connected with each other due to hydrogen bonding with participation of caffeine (caf) and water molecules, were prepared and characterized by the powder and single crystal X-ray diffraction, IR vibrational spectroscopy, 1 H NMR, ESI-MS spectroscopy, thermal analysis and DFT calculations. It was found that the complexes ( I ) and ( IV ) are characterized by tetrahedral geometry, the caffeine molecule being coordinated by the central atom via its N 9 atom. The preferability of complex formation was evaluated by quantum-chemical calculations. Cyto- and genotoxicity of the compounds have been investigated and discussed in comparison with that of [Zn(AP) 2 I 2 ] ( 1 ) and [Cd(AP) 6 ][Cd(AP)I 3 ] 2 ( 2 ). It was demonstrated that the prepared complexes, primarily that of cadmium iodide with caffeine ( II ), are the promising ones for further studies both in vitro and in vivo .