Understanding the basic chemical properties of astatine is a major challenge: It is mostly produced in cyclotrons, and since it has only short-lived isotopes, experimental investigations are led at ultra-trace concentrations and so the Pourbaix diagram (or E_H-pH diagram) remains unfinished. A Pourbaix diagram gives information on behavior of a system as the pH and potential vary. However, there is increasing interest in astatine, especially astatine-221 (²²¹At) radionuclide, for use in nuclear medicine.

It is generally assumed that astatide (At⁻) is the predominant astatine species in basic aqueous media. Nicolas Galland and Gilles Montavo, Université de Nantes, France, and co-workers questioned this assumption in non-complexing and non-reductive aqueous solutions and combined chromatography, competition experiments, and quantum mechanical calculations to prove it. Contrary to what is usually believed, they found that At⁻ is a minor species at pH = 11. Rather, they identified the AtO(OH)₂⁻ species as the one that predominates in non-complexing and non-reductive basic aqueous solutions.

Beyond being a fundamental steps towards the completion of the Pourbaix diagram of astatine, this new information is of interest for the development of ²¹¹At radiolabeling protocols.

• Advances on the Determination of the Astatine Pourbaix Diagram: Predomination of AtO(OH)₂^– over At^– in Basic Conditions,
  Dumitru-Claudiu Sergentu, David Teze, Andréa Sabatié-Gogova, Cyrille Alliot, Ning Guo, Fadel Bassal, Isidro Da Silva, David Deniaud, Rémi Maurice, Julie Champion, Nicolas Galland, Gilles Montavon,
  Chem. Eur. J. 2016.
  DOI: 10.1002/chem.201504403