Solvation of inorganic nitrate salts in protic ionic liquids

The bulk nanostructure of several inorganic salt solutions in protic ionic liquids is elucidated using neutron diffraction and empirical potential structure refinement modeling. The protic ionic liquids studied are ethylammonium nitrate (EAN) and ethanolammonium nitrate (EtAN), which are mixed with either LiNO3, Mg(NO3)2, Ca(NO3)2, or Al(NO3)3 at 1:10 or 1:30 solute:solvent mol:mol ratios. The models show inorganic metal ions are solvated within the polar domains of the nanostructure and can induce significant differences in bulk solvent nanostructure from that of the pure ionic liquids. For EtAN, the uncharged groups aggregate and form an apolar domain in spite of the cation’s reduced amphiphilicity because the trans rotamer is favored when an inorganic salt is added.