X-ray and molecular dynamics studies of butylammonium butanoate–water binary mixtures

Abstract

The nanostructural organisation of mixtures of the ionic liquid (butylammonium butanoate) and water at several mole fractions of water has been investigated using small and wide angle X-ray scattering (S-WAXS) and molecular dynamics (MD) simulations. The presence of a first sharp diffraction peak (FSDP) in the pure ionic liquid has been observed, experimentally and theoretically, suggesting the possibility of segregation of domains of different polarity in the system. With increasing dilution in water, the prepeak is shifted towards smaller Q values, and becomes very weak, while the principal peak moves towards larger Q values. These phenomena suggest the disruption of the hydrogen-bonded network of the ionic liquid, primarily through hydrogen bonding of the anion to water, a conclusion supported by MD simulations.

Bio ionic liquids and water mixtures: a structural study

“…In all the solutions considered, the water molecules tend to form a more stable H-bond interaction with the cation, with respect to the anion. This nding is in partial disagreement with a recent study by some of us, 37 where water-anion interactions were deemed responsible for the disruption of the hydrogen bond network of butylammonium butanoate. Likely, the partially bidentate interaction between choline and aminoacid anion (hydroxyl-quaternary ammonium/carboxylate), 38 is stronger than the simpler ammonium-carboxylate correlation.…”

New Insights into the Structure of Glycols and Derivatives: A Comparative X-Ray Diffraction, Raman and Molecular Dynamics Study of Ethane-1,2-Diol, 2-Methoxyethan-1-ol and 1,2-Dimethoxy Ethane

“…Summarizing, the analysis of both reciprocal space (q I(q) M(q)) and distance space (Diff (r)) functions is used to compare X-ray experimental data and simulations. This methodology has been successfully applied to the study of molecular [27][28][29], ionic liquids [30,31], deep eutectic solvents [32] as well as solutions [33][34][35][36].…”

New Insights Into the Structure of Hydroxylated and Alkylated Glycols: A Comparative X-ray Diffraction, Raman and Molecular Dynamics Study of Ethane-1,2-Diol, 2-Methoxyethan-1-ol and 1,2-Dimethoxy Ethane

“…Considering that the molecules considered in this study also differ for short range correlations (i. e. molecular conformations and intra-molecular hydrogen bonding), we decided to use the "sharpened" version of the structure factor, q I(q) M(q), that highlights such differences at large q and when comparing model and experimental data, instead of the S(q) function that is less detailed t large q. Summarizing, the analysis of both reciprocal space (q I(q) M(q)) and distance space (Diff (r)) functions is used to compare X-Ray experimental data and simulations. This methodology has been successfully applied to the study of molecular [27][28][29], ionic liquids [30][31], Deep Eutectic Solvents [32] as well as solutions [33][34][35][36]. [37].…”