PPTMP: An Asymmetric Tetradentate Ligand for Trivalent Lanthanide/Actinide Separation in Nuclear Waste Management

This work presents a new type of asymmetric tetradentate N-donor ligand, (4-(6-(1,10-phenanthrolin-2-yl)pyridin-2-yl)-1H-1,2,3-triazol-1-yl)methyl pivalate (PPTMP), designed for the separation of trivalent actinides and lanthanides in nuclear waste management. Solvent extraction studies show that Am(III)/Eu(III) separation is achieved at low nitric acid concentrations, demonstrating the viability of this novel ligand type. The coordination chemistry of the ligand with Ln(III) and An(III) ions was investigated using X-ray diffraction (XRD) as well as nuclear magnetic resonance (NMR) spectroscopy, time-resolved laser fluorescence spectroscopy (TRLFS) and absorption spectroscopy (UV/vis). These methods show the formation of 1:1 and 1:2 complexes in different media, providing insight into the molecular mechanisms of f-element separation and highlighting the need for improved ligand design in nuclear waste management.