Aqueous solutions of binary ionic liquids: insight into structure, dynamics, and interface properties by molecular dynamics simulations and DFT methods

Molecular Insights into Binary Ionic Melts of Protic Ionic Liquid 1,2,4-Triazolium Methanesulfonate and Methanesulfonic Acid Electrolytes

Binary ionic melts formed by a protic ionic liquid (PIL) 1,2,4-triazolium methanesulfonate ([TAZ][MS]) dissolved in methanesulfonic acid are studied as non-stoichiometric electrolytes. The composition-driven structure-property relationship of methanesulfonic acid is explored at varying molar fraction ratios from 0/100 to 10/90, 20/80, and 30/70 by the addition of 1,2,4-triazolium methanesulfonate [TAZ][MS] IL. To unveil molecular characteristics of these mixtures of [TAZ][MS] PIL and CH3SO3H, we performed classical molecular dynamics simulations at varying temperatures from 293 to 303, 363, and 423 K. Ion-pair interactions and ion-solvent interactions are captured through various atom-atom radial distribution functions, and hydrogen bonding is presented through N-H hydrogen atom interactions with the [MS]- anion or CH3SO3H oxygen atoms. Apart from the temperature, the PIL ratio itself plays a critical role in hydrogen bonding interactions, and spatial density distribution maps show strengthening of ion-pair interactions with an increase in PIL concentration. The mobility of ions and CH3SO3H is also explored through mean square displacement plots and by calculating the diffusion coefficient. The diffusion coefficient is used to calculate Nernst-Einstein conductivity, which shows an excellent match with experimental conductivity at 363 and 423 K.

Ionic liquids as a useful tool for tailoring active pharmaceutical ingredients

Ionic liquids (ILs) have been widely used in biomedical and pharmaceutical fields as solvents or permeation enhancers. Recently, more and more researchers focused on optimizing the physicochemical properties of active pharmaceutical ingredient (API) by ILs technology. Converting APIs into ILs (API-ILs) has shown great potential for drug delivery by eliminating polymorphism, tailoring solubility, improving thermal stability, increasing dissolution, controlling drug release, modulating the surfactant properties, enhancing permeability of APIs and modulating cytotoxicity on tumor cells. In addition, API-ILs are also used in various formulations as active ingredients, such as solutions, emulsions, even tablets or nanoparticles. This paper aims to review current status of API-ILs, including the rational and design, preparation and characterization, the improvement on the physicochemical characteristics of APIs, the compatibility of API-ILs with various formulations, and the future prospects of API-ILs in biomedical and pharmaceutical fields.