Exploration of Diverse Interactions of l-Methionine in Aqueous Ionic Liquid Solutions: Insights from Experimental and Theoretical Studies

Abstract

Here, we have investigated some physicochemical parameters to understand the molecular interactions by means of density (ρ) measurement, measurement of viscosity (η), refractive index(n D ) measurement, and conductance and surface tension measurements between two significant aqueous ionic liquid solutions: benzyl trimethyl ammonium chloride (BTMAC) and benzyl triethyl ammonium chloride (BTEAC) in an aqueous Lmethionine (amino acid) solution. The apparent molar volume (Φ v ), coefficient of viscosity (B), and molar refraction (R M ) have been used to analyze the molecular interaction behavior associated in the solution at various concentrations and various temperatures. With the help of some important equations such as the Masson equation, the Jones−Doles equation, and the Lorentz−Lorenz equation, very significant parameters, namely, limiting apparent molar volumes (Φ v 0 ), coefficient of viscosity (B), and limiting molar refraction (R M 0 ), respectively, are obtained. These parameters along with specific conductance (κ) and surface tension (σ) are very much helpful to reveal the solute−solvent interactions by varying the concentration of solute molecules and temperature in the solution. Analyses of Δμ 1 0# , Δμ 2 0# , TΔS 2 0# , ΔH 2 0#, and thermodynamic data provide us valuable information about the interactions. We note that L-Met in 0.005 molality BTEAC ionic liquid at 308.15 K shows maximum solute−solvent interaction, while L-Met in 0.001 molality BTMAC aqueous solution of ionic liquid at 298.15 K shows the minimum one. Spectroscopic techniques such as Fourier transform infrared (FTIR), 1 H-NMR, and UV−vis also provide supportive information about the interactions between the ionic liquid and L-methionine in aqueous medium. Furthermore, adsorption energy, reduced density gradient (RDG), and molecular electrostatic potential (MESP) maps obtained by the application of density functional theory (DFT) have been used to determine the type of interactions, which are concordant with the experimental observations.

Exploration of Solvation Consequences of Ionic Liquids Prevalent in the Aqueous Media of Food Additive Azo Dye Tartrazine by Physicochemical and Computational Studies

“…Because the molal conductivity constantly decreases with increasing tartrazine concentrations of ionic species, the mobility of ionic species in an aqueous IL solution is significant. , The ion-hydrophilic, ion-hydrophobic, and hydrophobic-hydrophobic interactions associated with the azo dye (tartrazine) in three ILs may be responsible for the enhanced solute–solvent interaction. As the molecular assembly between the azo dye molecule and ILs develops, ionic species lose their subsequent powers of movement in the solution phase, making them less mobile and less able to demonstrate conductivity in a solution . Conductimetric results confirm the volumetric, viscometric, and refractometric data and reaffirm a similar understanding.…”

“…To find the limiting molar conductivity (Λ 0 ) of azo dye TZ in IL solutions, linear conductivity curves between Λ and c were extrapolated to c = 0. Following that, it was found from Table and Figures – that the molar conductivity (Λ) values of the three mentioned systems increase with increasing temperatures and the gradual addition of tartrazine to the three IL systems in different concentrations, causing a continuous decrease in molal conductivity of the solution . However, the values for tartrazine in an aqueous solution of BTBAC are lower under all conditions.…”

“…The values of Δμ 2 0⧧ are considered as a free energy transfer between the two IL phases. The probability of molecules remaining in the ground state is greater than that of the excited state, as indicated by the fact that all of the values of Δμ 2 0⧧ are positive and significantly higher than the value of Δμ 1 0⧧ Table illustrates that interactions associated with the ground state are significantly stronger than those connected with the transition state because Δμ 2 0⧧ > Δμ 1 0⧧ for both analyzed systems.…”

“…The Φ V 0 values of tartrazine solutions were carefully observed at 0.001, 0.003, and 0.005 molalities of the ILs at 298.15, 308.15, and 318.15 K, respectively. When the concentration of the solutions increases, the values of Φ V 0 seem to increase as well . The solvent molecules serve as the only boundaries for the solute molecule, which stays infinitely apart from them.…”

Exploring Various Molecular Interactions of Two Essential Amino Acids Prevalent in Aqueous Solutions of an Ionic Liquid by Density, Viscosity, Refractive Index, Conductance, Surface Tension, Nuclear Magnetic Resonance, Ultraviolet, and Computational Studies

“…The apparent molar volume (ϕ v ) has been calculated by using eq 5, and the values appeared are enlisted in Tables S5−S7. 35 Ä…”