Ricerc@Sapienza

Room temperature ionic liquids (RTILs) are salts made by an organic cation and an organic/inorganic anion, which are at the liquid state at 25 °C. They have attracted much attention as a more sustainable alternative to traditional solvents owing to their negligible vapor pressure, non-flammability, thermal stability, wide electrochemical windows, good solvation ability and lower toxicity. Due to these characteristics, RTILs have been proposed as new electrolytes for energy storage systems and as new media for catalysis, electrodepositions, chemical extractions and pharmaceutical research. Several of these applications also involve the presence of metal ions as solvated species in RTILs. In this framework, a deep knowledge of the structural solvation features of a metal ion in these media becomes essential to design new applications. However, this knowledge still lacks for many metal ions in several RTILs.
Available literature data about Ag(I) solvation in RTILs provide a very encouraging picture for the potential applications involving this metal ion in these solvents. This is particularly true for what concerns the employment of RTILs as receiving phase for chemical separations, since high extraction rates of Ag(I) have been obtained with RTILs carrying the [Tf2N]- (bis(trifluoromethanesulfonyl)imide) anion. Solvation thermodynamic data confirm this trend, showing favorable free energies of transfer from water to [C4mim][Tf2N] and [C4mim][BF4] (1-alkyl-3-butyl-imidazolium bis(trifluoromethanesulfonyl)imide) and tetrafluoroborate). However, no definite picture about Ag(I) coordination in these RTILs is available.
For these reasons, the purpose of this project is to study the solvation of Ag(I) in these RTILs from a structural point of view. In particular, both experimental (X-ray absorption spectroscopy - XAS) and theoretical methods (molecular dynamics simulations - MD) will be employed to obtain a detailed picture of the metal-solvent interactions in solution.