From potential contamination of individuals with radioactive fission products after a nuclear accident to the therapeutic use of radio-isotopes for cancer diagnostics and treatment, the biological chemistry of actinides has become increasingly relevant to a number of applied problems. Understanding the fundamental bonding interactions of selective metal assemblies presents a rich set of scientific challenges and is critical to the characterization of f-element coordination chemistry in environmentally and biologically relevant species, and to the development of highly efficient separation reagents or new therapeutic agents. Our approach to these challenges uses a combination of biochemical and spectroscopic studies on both in vitro and in vivo systems to characterize the selective binding of f-block metal ions by natural and biomimetic hard oxygen-donor architectures and the subsequent macromolecular recognition of the resulting assemblies.
Luminescence sensitization, UV-Visible, X-ray absorption, and X-ray diffraction spectroscopic techniques allow us to tune specific actinide coordination features by ligands that drive the differentiation of different metals through stabilization in specific oxidation states and provide information on their respective electronic structures. In addition, X-ray diffraction analyses using the mammalian iron transport protein siderocalin as a crystallization matrix reveals 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 5f-element sequence, when combined with theoretical predictions. These results will be discussed with a perspective on how such studies have important implications for the combined use of spectroscopic, thermodynamic, and biokinetic methods to exploit the fundamental knowledge of the role of f-electrons in actinide bonding for the development of new transport, separation, luminescence, and therapeutic applications.