Glycine in 1‐Butyl‐3‐Methylimidazolium Acetate and Trifluoroacetate Ionic Liquids: Effect of Fluorination and Hydrogen Bonding

Abstract

The solvation of glycine in two ionic liquids (ILs), namely, 1-butyl-3-methylimidazolium acetate, [C(1)C(4)Im][OAc], and 1-butyl-3-methylimidazolium trifluoroacetate, [C(1)C(4)Im][TFA], was studied by a combination of experimental and theoretical methods. The solubility of glycine in both ILs was determined at 333.15 K to be (8.1±0.5) and (1.0±0.5) wt % in [C(1)C(4)Im][OAc] and [C(1)C(4)Im][TFA], respectively. By IR spectroscopy it was found that, when dissolved in the ILs, glycine was mainly present in its zwitterionic form. Structural and energetic aspects of the solvation of glycine in the ILs and in mixtures of ILs and water were investigated by ab initio calculations and molecular dynamic simulations. It was observed that the firstly solvation shell around glycine consisted predominantly of acetate or trifluoroacetate anions, which formed hydrogen bonds either with the carboxylic group of neutral glycine or with the protonated ammonium group of the zwitterionic form. When water is present in the solutions, hydrogen bonds between water and the anion prevail. The overall energy of the system was decomposed into its components between pairs of species. It was established that the dominant contribution to the interaction energy between glycine and the IL was due to hydrogen bonds with the anions and the statistics of hydrogen bonds were analysed.

Structure and Nanostructure in Ionic Liquids

“…To date, the majority of these solutions have focused on Li + solvation in AILs, − motivated by interest in Li + batteries . Other papers have characterized the speciation of alkali metal and alkaline earth ions, , f-block compounds, , biomolecules (amino acids, peptides, − or proteins − ), or Ru 2+ dyes aimed at nuclear fuel processing, biopreservation, or organic photovoltaics, respectively. The results show that small, charged solutes completely dissociate in the bulk with the solute ions embedded in the polar domains of the IL nanostructure.…”

Electron donor ionic liquids entrapped in anionic and cationic reverse micelles. Effects of the interface on the ionic liquid–surfactant interactions

“…101 BmimTfA, which is an IL whose anion has very high electron donor ability 46,102 present a strong and almost symmetric band at 1689 cm À1 , which is attributed to asymmetric carboxylate stretching vibration. [103][104][105] The interaction of bmimTfA with solvents was studied in the past and the results showed that also affects this vibration mode. 102,105 For example, the n asym COO À values showed shifts to low wavenumbers upon addition of water (or methanol) to pure bmimTfA, 102,105 general understanding that carboxylate group is a good proton acceptor, the shifting was explained considering H-bonding interaction between water and TfA À .…”

Domain Analysis in Nanostructured Liquids: A Post‐Molecular Dynamics Study at the Example of Ionic Liquids

“…[16,17] Many interesting features of ILs can be alteredb yt heir functionalization. [21][22][23][24][25] Previously,w ei nvestigated fluorinated aprotic ionic liquids( FAILs) from classical molecular dynamics (MD) simulations, [26] for which we showedt hat nanosegregation is enhanced upon fluorination, but beside the effect of the size or the character of the side chain, the nature and size of the aniona lso influence the microheterogeneous structure. [19] Amongst the several possibilities, fluorination was also examined, [20] which resulted in fluorinated ionic liquids.…”