The interaction of organotins with native DNA

Abstract

Abstract The compounds R 2 SnCl 2 and R 3 SnCl (RMe, Et, nBu, nOct, Ph, in ethanol solution) as well as the aqueous species [Me 2 Sn(OH 2 ) n ] 2+ and [Me 3 Sn(OH 2 ) 2 ] + , react with aqueous native DNA, yielding solid phases. According to the pointcharge model treatment of the 119 Sn Mössbauer parameter nuclear quadrupole splitting, trans ‐octahedral R 2 Sn(O 2 PXY) 2 , and trigonalbipyramidal R 3 Sn(O 2 PXY), (RMe, Et, nBu), would occur in the pellets, the tin atoms being coordinated by phosphodiester groups of the nucleic acid. The precipitates from Ph 2 Sn IV would consist of the DNA complex as well as of the Ph 2 Sn IV distannoxane obtained by hydrolysis of the reactant, whilst nOct 2 SnCl 2 , nOct 3 SnCl and Ph 3 SnCl would mainly yield stannoxanes and hydroxides. The water‐soluble hydrolyzed species [Me 2 Sn(OH)(OH 2 ) n ] + , Me 2 Sn(OH) 2 and Me 3 Sn(OH)(OH 2 ) do not show any interaction with native DNA, although they are possibly coordinated by phosphate oxygen atoms in model aqueous systems, in the presence of excess ligand. These trends have been rationalized by QSAR approach (Quantitative Structure‐Activity Relationships) in terms of electronic factors related to tin‐oxygen (phosphate) Coulomb interactions, as well as the lipophilicity of R in the R n Sn IV moieties.