NRC-8, EuCheMS International Conference on Nuclear and Radiochemistry

ORAL PRESENTATION - Exploration of the metallic character of astatine

18 Sept 2012, 10:55

15m

Como, Italy

Oral Communications Chemistry of radioelements and Super Heavy Elements research Session 3 - Chemistry of radioelements and Super Heavy Elements research

Speaker

Gilles Montavon (Subatech, France)

Description

Astatine 211 is considered to be one of the most promising candidates for targeted alpha therapy (TAT)1, 2 and it is the subject of a wide research program in Nantes (France). Very few data on the chemistry of astatine (At) are available. On the one hand, At is a rare element and it has only short half-life radioactive isotopes. On the other hand, it is an “invisible” element: the amount of At-211 produced allows working at ultra trace concentrations (typically 10-11 to 10-15 M) and no spectroscopic techniques can be used to estimate At characteristics at the molecular level. As a result, At chemistry is not well understood. Based on these considerations, a research program has started in Nantes to explore the fundamental properties of At using a multi-disciplinary approach combining radiochemistry, analytical chemistry and molecular modelling competences. The object of this contribution is to present the main advances obtained during the last 8 years as regards especially to the particular metallic character of astatine. The methodology enabled us to define a Pourbaix diagram (Eh/pH diagram) for At in non-complexing acidic aqueous medium. We showed the existence of At-, and two stable At+ and AtO+ metallic forms of astatine.3, 4 This highlighted the metallic character of At by comparison with others halogens, as it was already proposed in the 60’s.5 Our recent results on the chemical reactivity of AtO+ demonstrate the potentiality to form both coordination and covalent bondswith organic and inorganic ligands.6, 7 1. D. S. Wilbur, Current Radiopharmaceuticals, 2008, 3, 144-176. 2. M. R. Z. Vaidyanathan G., Current Radiopharmaceuticals, 2008, 1, 177-196. 3. J. Champion, C. Alliot, E. Renault, B. M. Mokili, M. Cherel, N. Galland and G. Montavon, The Journal of Physical Chemistry A, 2010, 114, 576-582. 4. A. Sabatié-Gogova, F. Pottier, J. Champion, S. Huclier, N. Michel, N. Galland, Z. Asfari, M. Chérel and M. G., Analytical Chimica acta, 2012, 721, 182. 5. E. H. Appelman, J. Am. Chem. Soc., 1961, 83, 805-807. 6. J. Champion, C. Alliot, S. Huclier, D. Deniaud, Z. Asfari and G. Montavon, Inorganica Chimica Acta, 2009, 362, 2654-2661. 7. J. Champion, M. Seydou, A. Sabatie-Gogova, E. Renault, G. Montavon and N. Galland, Physical Chemistry Chemical Physics, 13, 14984-14992.