Sequestering agent for uranyl chelation: new binaphtyl ligands

Uranyl-sequestering agents based on 3-hydroxy-2(1 H)-pyridinone (3,2-HOPO), sulfocatecholamide (CAMS) and phosphonic Binaphyl were synthesised and evaluated towards their binding abilities for the uranyl cation. The synthesis of phosphonate, sulfocatecholamide (CAMS) and hydroxypyridinone (HOPO) binaphtyl ligands is presented. Their binding abilities for uranyl cation were determined by UV spectrophotometry in aqueous media versus pH. These titrations showed that the efficiency of these chelating agents depends on the nature of the chelating group. Each ligand shows a more or less pronounced affinity towards uranium. While the bisphosphonate compound did not show any affinity towards the uranyl ion, the BINHOPO derivative exhibits significant affinity at acidic and neutral pH while the BINCAMS is more efficient at basic pH.