Aqueous speciation studies of uranium in carboxyphosphonate medium

Probing the metrical knowledge about the uranium speciation and coordination in aqueous solution is essential, in the development of a predictive understanding of its solubility, stability, complexation, redox reaction, sorption and reactivity. Phosphonate based chelating agents emerge as tenable option as sequestering agent for f-elements. Carboxyphosphonates represents a variation on this where one of the phosphonate moieties has been replaced by a carboxylate group. The bifunctional nature is of interest as it has the propensity to promote the formation of bimetallic compounds, whereas the heterofunctionality allows us to consider the affinity of the actinides for carboxy and/or phosphonate oxygen atoms as well as metal-organic coordination modes. This would be consistent with comparative studies of phosphonates and carboxylates in solution. It is therefore worthwhile to study the complexation of uranium by two carboxyphosphonate chelating ligand namely, Phosphonoacetic acid (PAA) and Phosphonoformic acid (PFA). In the present work, the electrochemical and absorption spectroscopy methodology were employed to gain insight into the speciation and coordination chemistry of uranium with both ligands and to understand the effect of ring strain (5 and 6 member ring) during complexation