Selective Capture of Thallium and Cesium by a Cryptophane Soluble at Neutral pH

Thierry Brotin (1) , Patrick Berthault (2) , Delphine Pitrat (1) , Jean-Christophe Mulatier (1)

1 LC - Laboratoire de Chimie - UMR5182
2 LSDRM - Laboratoire Structure et Dynamique par Résonance Magnétique (LCF)

We report in this article the synthesis of a asymmetrical cryptophane derivative (possessing only C3-symmetry) bearing three phenol groups and three other carboxylic acid functions, each of these groups on the aromatic rings. Thanks to isothermal titration calorimetry experiments, we show that this compound binds large monovalent cations, such as Cs+ and Tl+ with a binding constant significantly lower than its congeners bearing a larger number of phenol groups grafted on the benzene rings. However, higher selectivity for Cs+ and Tl+ was observed with this compound since it does not show any affinity for other alkali cations. More importantly, due to the greater solubility of this derivative in pure water, we show for the first time that effective thallium(I) complexation takes place at neutral pH. This result demonstrates that cryptophane derivatives decorated with a higher number of phenol groups are promising host molecules for removing traces of thallium(I) from aqueous phases at neutral pH or above.

Domaines: Matériaux; Chimie de coordination

Thierry Brotin, Patrick Berthault, Delphine Pitrat, Jean-Christophe Mulatier. Selective Capture of Thallium and Cesium by a Cryptophane Soluble at Neutral pH. Journal of Organic Chemistry, 2020, 85, pp.9622-9630. ⟨10.1021/acs.joc.0c00950⟩. ⟨cea-02883381⟩