Synthesis, structure and cytotoxic activity of trans-[PtCl2(EugH)(Caffeine)] and [PtCl(Eug)(Caffeine)] (EugH: eugenol) complexes

Abstract

Interaction between K[PtCl₃(EugH)] (1) and [PtCl(Eug)]₂ (2) with Caf afforded two new complexes, trans-[PtCl₂(EugH)(Caf)] (3) and [PtCl(Eug)(Caf)] (4), respectively. The procedure to synthesize complex 2 was improved. The structures of two new complexes were characterized by elemental analyses, MS, IR, ¹H NMR and NOESY spectroscopies. The result indicated that EugH coordinates with Pt(II) at ethylenic double bond of the allyl group in complex 3, but in complex 4 it is deprotonated and bound with Pt(II) at both the double bond and C5 of the benzene ring. The donor N of caffein is in trans-position in 3 and in cis-position in 4 with respect to the ethylenic double bond. In chloroform solvent, 4 exists in two forms 4a and 4b corresponding to the strong intermolecular hydrogen bond Cl₃C-H…ClPt(II) and the strong halogen bond Cl₂HC-Cl…Pt(II). The result of testing cytotoxicity of 3 and 4 against four human cancer cells KB, Lu, Hep-G2 and MCF7 showed that complex 3 exhibits good activities on the KB and Hep-G2 with IC₅₀ values of 81,03 and 89,29 μg/mL, respectively.