F-Element coordination and extraction selectivity of a carbamoylmethylphosphine oxide ligand based on a tripodal phosphine oxide scaffold

Abstract

We report here the synthesis and study of a multipodal ligand bearing three CMPO units attached to a trialkylphosphine oxide cap along with the resultant Ln3+, Th4+ and UO22+ metal complexes. This tripodal ligand demonstrates extraction efficiencies of 47% and 44% for the actinide species Th(NO3)4 and UO2(NO3)2 out of 1M nitric acid into a solution of dichloromethane, while all lanthanide nitrates were extracted with relatively low efficiencies. Further extraction studies utilizing 5M nitric acid solutions resulted in nearly quantitative actinide extraction. The ability of this ligand to sensitize the metal-centered luminescence of Eu3+ and Tb3+ in DMSO solutions was also investigated. Finally, possible conformations for the structure of the [La(NO3)-ligand]2+ complex were calculated using density functional theory.