Synthesis, characterization and biological studies of diorganotin(IV) complexes with tris[(hydroxymethyl)aminomethane] Schiff bases

Abstract

Several Schiff base ligands derived from tris(hydroxymethyl)aminomethane were synthesized and a series of diorganotin(IV) complexes were obtained from the reaction of diorganotin dichlorides or oxides with Schiff base ligands. The ligands and complexes have been characterized by elemental analysis, IR, 1H, 13C and 119Sn NMR spectroscopies. Single-crystal X-ray diffraction analysis reveals that bis[(2-{[1,1-bis(hydroxymethyl)-2-oxidoethyl]iminomethyl}phenolato)]dimethyltin(IV), 1 and bis[(2-{[1,1-bis(hydroxymethyl)-2-oxidoethyl]iminomethyl}-4-bromophenolato)]dimethyltin(IV), 7 are dimeric structures, in which the central tin atom is rendered six-coordinate while (2-{[1,1-bis(hydroxymethyl)-2-oxidoethyl]iminomethyl}-4-bromophenolato)diphenyltin(IV), 9, (2-{[1,1-bis(hydroxymethyl)-2-oxidoethyl]iminomethyl}-4-chlorophenolato)dimethyltin(IV), 13, (2-{[1,1-bis(hydroxymethyl)-2-oxidoethyl]iminomethyl}-4-chlorophenolato)diphenyltin(IV), 15 and (2-{[1,1-bis(hydroxymethyl)-2-oxidoethyl]iminomethyl}-4-chlorophenolato)dicyclohexyltin(IV), 16 are monomeric structures, whereby the tin atom is in a distorted trigonal–bipyramidal configuration. The Schiff bases and their corresponding diorganotin(IV) complexes have been evaluated against three human carcinoma cell lines, namely HT29 (human colon carcinoma cell line), SKOV-3 (human ovarian cancer cell line) and MCF-7 (hormone-dependent breast carcinoma cell line), for its in vitro cytotoxic activities. The dibutyltin and dicyclohexyltin derivatives of the Schiff base ligands display good cytotoxic activities against the tested cell lines.