Crystal structures, DNA-binding ability and influence on cellular viability of gold(I) complexes of thiosemicarbazones

Abstract

The present study reports the synthesis and crystal structure of four novel gold(I) complexes with di-2-pyridyl ketone N(4)-ethylthiosemicarbazone (L1) and 2-acetylfuran-4-methyl-3-thiosemicarbazone (L2). All the gold(I) complexes were observed with monodentate thiosemicarbazones and exhibited gold(I) ions with linear geometries, bound to a sulfur atom of the ligand and a halogen ion (Br− or Cl−). The crystal structures of gold complexes with Br− and thiosemicarbazone are the first examples reported. Interestingly, 2[AuBr(HL1)]2Br was observed to have a Au⋯Au length of 3.155(8) Å, and this distance suggests an unusual Au⋯Au interaction in the solid state. The ability of the thiosemicarbazones and the corresponding gold(I) complexes to bind to DNA was studied by UV-vis and emission spectroscopy. The effect on cell viability of the compounds was evaluated against human breast cancer cell lines. The results show that the gold(I) complexes exhibit more potent inhibition of tumor growth than the free ligands.