A density functional theory study on the water aggregation behaviour of fatty acid-based anionic surface active ionic liquids

Abstract

The hydrogen bond interactions between methyl-imidazolium cation (MIM + ) and fatty-acid anions (C m H n COO -, where m=1-6; n-3-13) of ionic liquids are studied in both gas phase and water phase using density functional theory. The structural properties show that the presence of N-H m=1-6;n-3-13) ionic liquids. From the vibrational frequency analysis it was found that the hydrogen bond interaction between [MIM] + and [C m H n COO] -(m=1-6;n-3-13) ionic liquids are red-shifted in frequency. The natural bond orbital analysis show that the N-H•••O hydrogen bond associated with the large charge transfer which has the higher stabilization energy (i.e. E (2) ~ 38 kcal/mol). Further, the cation/anion-water cluster (H 2 O) 1-3 interactions show that the water molecules are preferred to interact with anions. In the case of ionic liquids-water cluster interaction, the water molecules occupies the interstitial space between cation and anion of ionic liquids which results in weakening the cation-anion interaction.

Investigation of Sulfonium-Iodide-Based Ionic Liquids to Inhibit Corrosion of API 5L X52 Steel in Different Flow Regimes in Acid Medium

“…Table reports the lengths and bond angles for each group of atoms. It is observed that the C–C, S–C, and C–H bonds did not present changes in vacuum and aqueous medium [employing COSMO (COnductor-like Screening MOdel) as the solvation model, which uses a dielectric constant of 78.4 to simulate the medium] . In contrast, the space between sulfur and iodide shows slight distancing (∼0.33 Å), which increased the interaction capacity with other molecules.…”

“…It is observed that the C–C, S–C, and C–H bonds did not present changes in vacuum and aqueous medium [employing COSMO (COnductor-like Screening MOdel) as the solvation model, which uses a dielectric constant of 78.4 to simulate the medium]. 96 In contrast, the space between sulfur and iodide shows slight distancing (∼0.33 Å), which increased the interaction capacity with other molecules. As for the bond angles of the different atom groups, they presented negligible variations when the medium was changed, suggesting that the distribution of the [DDMS + I – ] atoms was not affected.…”