Di- and tri-organotin(IV) complexes with 2-hydroxy-1-naphthaldehyde 5-chloro-2-hydroxybenzoylhydrazone: Synthesis, characterization and in vitro antitumor activities

Series of new organotin(IV) complexes of the types R2SnL, R is Me (1), Ph (2), o-Cl–C6H4CH2 (3); and [R3SnL]∞, R = n-Bu (4) (H2L = 2-hydroxy-1-naphthaldehyde 5-chloro-2-hydroxybenzoylhydrazone) have been synthesized and structurally characterized by means of elemental analysis, FT-IR, UV–vis spectroscopy, NMR (1H, 13C and 119Sn) spectra and X-ray single crystal diffraction analyses. Structural analyses reveal that complexes 1–3 show similar monomeric structure, in which the tin center is coordinated with the enolic tridentate ligand (L) in the ONO chelate mode and exhibits five-coordinated trigonal bipyramidal geometry. Unexpectedly, complex 4 presents as a rare one-dimensional chain polymeric structure, in which the coordination of Sn is also five-coordinated trigonal bipyramidal geometry and the segment of tri-n-butyltin is bridged by the de-protonated phenolate O atom and the carbonyl O atom from the non-enolic Schiff base ligand. All compounds exhibit good in vitro antitumor activity toward human colon cancer cells (HCT-8), lung cancer cells (A549) and human promyelocyticfina leukemic cells (HL-60). The results indicate that both alkyl groups bound with tin centers and the structural of organotin compounds have significant effect on their in vitro antitumor activities. Among them, the polymeric tri-n-butyltin Schiff base complex 4 is the most active one, and the complex 3 shows high selectivity on the tumor cells HCT-8 and HL-60. For all of the title compounds, there was a good dose–effect relationship.