Elucidating the coordination chemistry of the radium ion for targeted alpha therapy.

The coordination chemistry of Ra 2+ is poorly defined, hampering efforts to design effective chelators for 223 Ra-based targeted alpha therapy. Here, we report the complexation thermodynamics of Ra 2+ with the biomedically-relevant chelators DOTA and macropa. Our work reveals the highest affinity chelator to date for Ra 2+ and advances our understanding of key factors underlying complex stability and selectivity for this underexplored ion.