Abstract: Lanthanide rare-earth metals are integral to modern technologies, yet the chemistry of promethium (Pm), the 61st element, remains largely unexplored due to its high radioactivity and inaccessibility. Despite its significance, Pm has been notably absent from experimental studies, hindering our understanding of the lanthanide contraction—a key concept in the periodic table discussed in general chemistry textbooks. In this talk, I will present the successful chelation of the 147Pm radionuclide (with a half-life of 2.62 years) in an aqueous solution using a newly synthesized organic diglycolamide ligand. The resulting homoleptic PmIII complex was investigated through synchrotron X-ray absorption spectroscopy and quantum chemical calculations, revealing the coordination structure and bond distance of promethium. These findings enable a comprehensive structural analysis of a complete set of isostructural lanthanide complexes, capturing the lanthanide contraction in solution solely based on experimental data. Our results demonstrate accelerated bond shortening at the beginning of the lanthanide series, correlating with separation trends observed in diglycolamides. The characterization of the radioactive PmIII complex in an aqueous environment enhances our understanding of intra-lanthanide behavior and the chemistry and separation of f-block elements.

Short Bio: Dr. Alex Ivanov is a Research Staff Scientist in the Chemical Sciences Division at Oak Ridge National Laboratory. He received his Ph.D. from Utah State University in 2015. Dr. Ivanov’s research lies broadly in the development and application of neutron/X-ray scattering and spectroscopy techniques and theoretical methods to investigate processes and functional materials for energy-relevant technologies, including chemical separations, molecular recognition, radiotherapy, nuclear materials, and sustainability. His recent projects include fundamental investigations of lanthanide and actinide contraction phenomenon in solution and elucidating coordination chemistry of radiopharmaceutical compounds using synchrotron X-ray absorption spectroscopy.

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In-Person Location:  Bldg. 440, A105/A106

Virtual Link: https://argonne.zoomgov.com/j/1613912289