ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P173. Synthetic Approaches in the Aqueous Structural Speciation of Binary
Cr(III)-hydroxycarboxylate Systems. Relevance to Chromium Toxicity
A. Salifoglou, C. Gabriel
Department of Chemical Engineering, Aristotle University of Thessaloniki, Corner of Egnatia and 3rd
September St, 54124, Thessaloniki, Greece
e-mail: salif@auth.gr
Chromium has since long been considered as a metal with widespread applications in industry [1]. Its biological
role [2], albeit conjectured to a great extent, has been the subject of considerable research efforts due to its
proclivity to induce toxic effects in lower and higher organisms [3, 4, 5]. Poised to comprehend chromium
toxicity at the molecular level, synthetic efforts were launched targeting the aqueous binary interactions of
Cr(III) with citric acid. The latter substrate is abundantly present in biological fluids and exhibits a diverse
chemical reactivity toward metal ions. To that end, synthetic efforts in the specific binary system led, in a pHdependent
fashion, to the isolation of discrete Cr-citrate species, such as (NH4)4[Cr(C6H4O7)(C6H5O7)]•3H2O (1),
in the solid state [6]. The structure of such species reveals a mononuclear octahedral Cr(III) complex with two
citrate ligands bound to it. Detailed aqueous speciation studies in the Cr(III)-citrate system suggest the presence
of a number of species, among which is the mononuclear [Cr(C6H4O7)(C6H5O7)] 4- complex at pH ~5.5. The
collective physicochemical data of these species in the solid state and in solution a) emphasize the importance of
concerted synthetic and aqueous speciation studies in the binary Cr(III)-citrate system, and b) denote the
ramifications of well-defined soluble Cr(III)-species in comprehending the arisen chemical reactivity that could
be linked to toxicity at the cellular level.
References:
[1] Bae, W.-C.; Lee, H.-K.; Choe, Y.-C.; Jahng, D.-J.; Lee, S.-H.; Kim, S.-J.; Lee, J.-H.; Jeong, B.-C. J.
Microbiology 2005, 43, 21-27.
[2] Ramos, R. L.; Martinez, A. J.; Coronado, R. M. G. Water Sci. Technol. 1994, 30, 191.
[3] Pettrilli, F. L.; Miller, W. Appl. Environ. Microbiol. 1977, 33, 805-809.
[4] Levis, A. G.; Bianchi, V. Biological and environmental aspects of chromium, S. Langard, Ed.; Elsevier
Science, Amsterdam, 1982, p. 171-208.
[5] Walsh, A. R.; O’Halloran, J.; Gower, A. M. Ecotoxicol. Environ. Safety 1994, 27, 168.
[6] Gabriel, C.; Raptopoulou, C. P.; Terzis, A.; Tangoulis, V.; Mateescu, C.; Salifoglou, A. Inorg. Chem. 2007,
46, 2998-3009
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