Interaction of 1-hexyl-3 methylimidazolium bromide ionic liquid with methylparaben drug in aqueous solution: conductometric and molecular dynamics studies

Abstract

In this research, the thermodynamic properties and molecular interactions of 1-hexyl-3-methylimidazolium bromide + methylparaben + water system were reported using conductometric method and molecular dynamics simulations. The conductometric data were collected for 1-hexyl-3-methylimidazolium bromide ionic liquid from 0.0012 to 0.1983 mol kg⁻¹ on various molality of methylparaben in aqueous solution (m_MP = 0.0000, 0.0005 and 0.0010 mol kg⁻¹) at T = (300.2, 310.2 and 320.2) K and P = 0.1 MPa. Fuoss–Onsager equation was applied to get the ion association constants and limiting molar conductivities of ionic liquid and to determine the thermodynamic of ion association. Moreover, molecular dynamics simulations were made to understand the interactions between ionic liquid and methylparaben at the molecular and microscopic level. Radial distribution functions, root-mean-square deviations, hydrogen bonding and van der Waals and electrostatic interactions were obtained. Furthermore, the diffusion coefficients of ionic liquid in methylparaben and water mixtures were obtained from molecular dynamics simulation to calculate the molar conductivity of 1-hexyl-3-methylimidazolium bromide using Einstein’s Nernst equation at T = 310.2 K and were in agreement with experimental molar conductivity.