A novel tripodal CMPO ligand: Affinity for f-elements, computational investigations and luminescence properties

Abstract

The synthesis and characterization of a new ligand bearing three carbamoylmethylphosphine oxide (CMPO) groups linked with a tris(2-aminoethyl)amine (TREN) capping scaffold is reported. Lanthanide and actinide complexes with this tripodal, hexadentate ligand have been prepared and characterized in solution and in the solid state. Further, we have investigated the general f-element binding and coordination geometries of these complexes using computational methods. This ligand demonstrates low extraction ability within the series of f-elements studied as rationalized by the computational data and protonation behavior presented. Modest extraction selectivity was observed, however, for Tb3+. Sensitization of Eu3+ and Tb3+ in solutions of methanol is also achieved by the ligand and the resultant photophysical properties are discussed. Luminescence lifetime data for the Eu3+ complex have been used to determine a value of approximately 1.5 bound solvent molecules in solution, providing further insight into the f-element coordination chemistry of this new CMPO-based ligand.