Computational Investigation of Binding Energetics of a CMPO Ligand for Selective Lanthanide Extraction

Mikayla Y. Darrows, Eric J. Werner, Olaseni Sode

University of Tampa

The development of ligands that selectively bind to lanthanide (Ln) and/or actinide (An) ions found in nuclear waste is an important area of research. When isolated, lanthanides have various applications such as contrast agents in medical imaging and as advanced luminescent materials. In order to understand the selectivity of potential f­-element extractants, computational tools were used to model a tripodal ligand containing three carbamoylmethylphosphine oxide (CMPO) groups attached to a tris(2-aminoethyl)amine (TREN) or a tris(2-aminopropyl)amine (TRPN) cap bound to seven lanthanide ions (Ce³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, and Yb³⁺) . These structures were optimized with the NWChem electronic structure package using the PBE0 density functional, a 3-21G* basis set, and the Stuttgart RSC 1997 effective core potential. Each lanthanide, ligand, and Ln complex geometry was optimized individually and the binding energy was computed. The WebMO user interface was used to calculate bond distances between the ligand and lanthanide. Coordinating NO₃^- ions were also included and their effects on the binding energy and geometry are reported.