Structural Properties and Aggregation Behavior of 1-Hexyl-3-methylimidazolium Iodide in Aqueous Solutions

Abstract

The structural properties of 1-hexyl-3-methylimidazolium iodide ([C6mim]I)/water mixtures with molar ratios ranging from 1:1 to 1:200 have been investigated using molecular dynamics (MD) simulations with extended X-ray absorption fine structure (EXAFS) experimental data. The presence of a complex network of interactions among cations, anions, and water molecules has been highlighted from the MD simulations, even if water molecules have been found to interact preferentially with the I(-) anion. The EXAFS results show that, also for the 1:1 [C6mim]I/water mixture, the water molecules are placed next to the I(-) anion, and the I(-) hydration shell becomes more and more crowded with increasing water content. Tight ion pairs have been detected in the [C6mim]I/water mixtures with molar ratios from 1:1 to 1:12, while no ionic pairs were found in the most diluted solutions. The aggregation behavior has been determined from MD simulations with the aid of S(q) functions. For the most concentrated IL/water mixtures with molar ratios between 1:1 and 1:12 the existence of long-range structural correlations has been evidenced, even if the apolar chains are not completely segregated as expected for micelle-like structures. Conversely, for the 1:200 mixture, that is above the experimental critical aggregation concentration value, the alkyl chains are completely separated from each other.

TiCl4 Dissolved in Ionic Liquid Mixtures from Аb Initio Molecular Dynamics Simulations

“…Tackling this question, the theoretical investigation is a necessity. In this regards joint approaches between experiment and theory were carried out for example by D'Angelo and Serva to investigate the structural properties of geminal di-and monocationic imidazolium based ILs with halides especially in mixtures with water [52,53].…”

How Does CeIII Nitrate Dissolve in a Protic Ionic Liquid? A Combined Molecular Dynamics and EXAFS Study

“…The dissolution of lanthanoid(III) ions (Ln III ) in solvents with different polarity is widely employed for separation of these species in nuclear power technology and industrial processes . Organic solvents have been widely used to extract Ln III ions from the aqueous phase, but ionic liquids (ILs) may be ideal alternatives due to their excellent properties such as low vapor pressure, low combustibility, excellent thermal stability and favorable solvating properties for a range of polar and non‐polar compounds . To select the best performing solvent it is important to shed light on the molecular interactions taking place between the components of the mixture, especially as compared to the solvation properties of water where these ions are usually dissolved.…”

Thermophysical Properties of Binary Amide Anion-Based Ionic Liquids; TMPAFSA<i>_x</i>TFSA₁₋<i>_x</i>

“…Such melting behavior is particularly common in materials which exhibit polymorphism, and it has been recently reported that ionic liquid exhibits polymorphic behavior. [32][33][34][35][36][37][38][39] Also in this work, there are several solid phases which have different segmental motion due to polymorphism, such solid phase exhibited melting behavior below the temperature corresponding to the solidus line. Additionally, we got composition dependence of heat of fusion as Fig.…”