Voroshylova I. Physical and chemical properties and microstructure of binary mixtures based on imidazolium and pyridinium ionic liquids with acetonitrile and methanol

Object of investigation: regularities in formation of macroscopic properties, especially transport, in ion-molecular systems as a function of external components and thermodynamic parameters as well as the development of computer simulation methods for disordered condensed systems simulation. Objective: To elucidate the influence of temperature, solvent, structure and nature of counterions on the physical and chemical properties, structure and interparticle interactions in binary systems ionic liquid - molecular solvent. Methods and apparatus: conductometry, classical and quantum molecular dynamics simulation, quantum-chemical calculations, conductimeter, analytical balance, water thermostats, computers. Theoretical and practical results: found limiting molar conductivity and ion association constant can be used as standard reference data. The regularities in the mutual influence of cations and anions of ionic liquids to predict the maximum electrical conductivity of mixtures of ionic liquids with molecular liquids have been found, which is important for electrochemical applications. These microscopic data can be used to develop chemical power sources and supercapacitors with improved performance. The technique to develop a force field model and counterions charges account can be used for any ionic liquids and their mixtures. Proposed approach allows simulate such systems successfully. Novelty: it has been found that throughout the composition range - from pure ionic liquids until infinitely diluted solutions - observed the same structural motif - contact ion pair of ionic liquid with a anion above the imidazolium (pyridinium) ring of cation. A new method of developing a universal force field model for molecular dynamic simulation of liquid media with a high concentration of electric charge which takes into account the mutual polarization of the system by scaling the partial charges on the atoms interacting ions. It is shown that the position and size of the maximum on the dependence of specific electrical conductivity on ionic liquid mole fraction in their mixtures with molecular solvents depends on the size of the cation and anion and reflacts the concentration at which the ions in the system come in contact with the formation of the complex associates (clusters) . Degree of implementation: methodological and computational approaches to take into account polarization effects in highly polarized environment embedded in the learning process on chemical department as part of a special course "Molecular dynamics simulation of condensed disordered systems" for specialty "Computational chemistry and molecular design" for "Master" and "Specialist" students of chemistry of 5th year. Area: results can be used in laboratories, which develop chemical current sources.