Synthesis, characterization and biological activity of organotin compounds derived from organic acids
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Date
2009
Authors
Yip, Foo Win
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Abstract
A total of forty one organotin(IV) carboxylate complexes were synthesized and
categorized in Series A, B and C. The complexes were synthesized by the condensation
reaction between dialkyltin(IV) oxide, R2SnO (R= methyl and butyl), bis[tributyltin(IV)] oxide,
(Bu3Sn)2O or triphenyltin(IV) hydroxide, Ph3SnOH with the selected organic acids. The
complexes were characterized using CHN and Sn elemental analysis as well as spectroscopic
methods such as infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy
(1H, 13C, 1H-13C HMQC and 119Sn NMR). The complexes possess sharp melting points
indicating that they were fairly pure. The elemental analytical and calculated values were in
agreement with the predicted formula indicating the complexes are pure. Based on combination
of spectral studies (FTIR and NMR data), the tin atoms of complexes 3A, 4A, 7A, 8A, 9A,
10A, 13A, 14A, 21B, 25B, 28C, 30C, 32C, 34C and 37C were four-coordinated and possess a
distorted tetrahedral geometry. The tin atoms of complexes 12A, 16B, 17B, 18B, 19B, 20B,
22B, 27C, 29C, 31C, 33C, 35C and 36C were five-coordinated and possess a distorted trigonal
bipyramid geometry. Seven complexes have tin atoms which were six-coordinated with a
distorted octahedral geometry (2A, 5A, 11A, 23B, 26C, 38C, 39C and 41C). Complexes 15B,
24B and 40C with organodistannoxane structures possess tin atoms which were five- and sixcoordinated
due to the carboxylate anions being bonded to the tin atoms in a bidentate bridging
manner. Complex 1A is the only complex with a tin atom which was seven-coordinated with a
distorted pentagonal bipyramid geometry. In the present study, twenty complexes were isolated
as single crystals (2A, 3A, 4A, 8A, 10A, 15B, 16B, 19B, 23B, 25B, 27C, 28C, 29C, 31C, 33C,
34C, 35C, 37C, 39C and 41C) and from the single crystal data, the structures and geometries
of these complexes were established. Most of the tin atoms were either four-, five- or sixcoordinated.
However, only complex 2A possess a tin atom which is seven-coordinated.
Overall, all the organotin(IV) carboxylate complexes in Series A, B and C showed significant
biological activities based on the in vitro cytotoxic assays and on the antibacterial and
antifungal screening activities. In general, among the tri- and di-organotin(IV) complexes, the
triorganotin(IV) derivatives were found to display higher biological activities. However, in
antibacterial screening study, diorganotin(IV) derivatives (complexes 1A, 5A, 11A, 18B, 22B
and 38C) were found to be more active compared to the triorganotin(IV) derivatives which
contradicts with the widely accepted norm that the increase in the number of organo groups
enhances the biological activities of the organotin(IV) complexes. This observation may be due
to the role of the anionic ligands in facilitating the transportation of the active organotin(IV)
cationic group to the active sites of the cell.
Description
PhD
Keywords
Biological Science , Organotin compounds , Organic acids