Separation of actinides is a challenging task due to the similarities in their ionic radii and the existence of most of these metal ions in the trivalent oxidation state. Understanding the fundamental bonding interactions between those metal centers and selective ligands presents a rich set of scientific challenges and is critical to the development of new separation strategies. Our studies utilize luminescence sensitization, UV-Visible, X-ray absorption, and X-ray diffraction spectroscopic techniques to investigate specific transcurium actinide coordination features by bio-inspired catecholamide and hydroxypyridinone hard oxygen-donor ligands. Using such ligands allowed the solution differentiation of Cm, Bk, and Cf, through stabilization of Bk(IV) under mild aqueous conditions. Resulting Cm(III) and Bk(IV) complexes exhibit sensitized luminescence features that provide information on their respective electronic structures. In addition, X-ray diffraction analyses using the mammalian iron transport protein siderocalin as a crystallization matrix revealed remarkable aspects of the protein’s interactions with chelated metals, establishing series of isostructural systems that can be used to derive trends in the later 5<i>f</i>-element sequence. Combined with theoretical predictions, these data add significant insight to the field of transcurium chemistry, and may lead to innovative characterization methods and separation processes.

Chelation past curium: Exploring trends in f-orbital bonding

254th National Meeting (2017)

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