Self-assembly of extended Schiff base amino acetate skeletons, 2-{[(2 Z)-(3-hydroxy-1-methyl-2-butenylidene)]amino}phenylpropionate and 2-{[( E)-1-(2-hydroxyaryl)alkylidene]amino}phenylpropionate skeletons incorporating organotin(IV) moieties: Synthesis, spectroscopic characterization, crystal structures, and in vitro cytotoxic activity

Abstract

The organotin(IV) compounds, [Ph 3SnL 1H] n · nCCl 4 ( 1), [Me 2SnL 2(OH 2)] ( 2), [ n Bu 2SnL 2] ( 3), [Ph 2SnL 2] n ( 4), [Ph 3SnL 2H] n ( 5) and [Ph 3SnL 3H] n ( 7) (L 1 = 2-{[(2 Z)-(3-hydroxy-1-methyl-2-butenylidene)]amino}phenylpropionate and L 2−3 = 2-{[( E)-1-(2-hydroxyaryl)alkylidene]amino}phenylpropionate), were synthesized by treating the appropriate organotin(IV) chloride(s) with the potassium salt of the ligand in a suitable solvent, while [ n Bu 2SnL 3(OH 2)] ( 6) was obtained by reacting the acid form of L 3 (generated in situ) with n Bu 2SnO. These complexes have been characterized by 1H, 13C, 119Sn NMR, ESI-MS, IR and 119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of 1 and 4– 7 were determined. The crystal structures of complexes 1, 5 and 7 reveal that the complexes exist as polymeric chains in which the L-bridged Sn-atoms adopt a trans-R 3SnO 2 trigonal bipyramidal configuration with R groups in the equatorial positions and the axial locations occupied by a carboxylate oxygen from the carboxylate ligand and the alcoholic or phenolic oxygen of the next carboxylate ligand in the chain. The carboxylate ligands coordinate in the zwitterionic form with the alcoholic/phenolic proton moved to the nearby nitrogen atom. A polymeric zig-zag cis-bridged chain structure is observed for 4, without considering the weak Sn⋯O interaction, the Sn-atom having a slightly distorted trigonal bipyramidal coordination geometry with the two O atoms of the tridentate amino propionate ligand in axial positions. On the other hand, the structure of 6 reveals a monomeric molecule in which the Sn-atom has a distorted octahedral coordination geometry involving the tridentate carboxylate ligand, two n-butyl ligands occupying trans-positions and one water ligand. The in vitro cytotoxic activity of triphenyltin(IV) compounds, viz., 1, 5 and 7 against WIDR, M19 MEL, A498, IGROV, H226, MCF7 and EVSA-T human tumor cell lines are also reported.