Seminar by Dr. Ranjit Biswas, Senior Professor, Dept of Chemical, Biological and Macromolecular Sciences,S. N. Bose National Centre for Basic Sciences, on "Dynamic Heterogeneity in Ionic Deep Eutectics: Anion and Temperature Dependance"

26 Dec 2018
Conference Room, 3rd Floor, Annex, Department of Chemistry
Talk Title : "Dynamic Heterogeneity in Ionic Deep Eutectics: Anion and Temperature Dependence"
Abstract
Time-resolved fluorescence measurements have reported strong fractional viscosity dependence of solute rotation and solvation times in ionic deep eutectics made of acetamide and electrolyte. Electrolytes considered areLiNO3, LiBr and LiClO4, and the temperature range coveredis ~100-180 Kabove the respectiveglass transition temperatures (Tg ~190 K).1-8Motional features of acetamide molecules at deep eutectic condition in these systemshave been followed in computer and analyzed.Simulated particle motions reflect substantial dependence of several heterogeneity features on the anion identity. Rise of solution temperature, as expected, softens the extent of micro-heterogeneous character of these multi-component melts. Simulated anion dependent four-point correlation functions suggest ~2-3 times variation in the correlated timescales, which responds rather strongly to the rise in solution temperature. Simulated correlatedlength-scale, on the other hand, suggesta much weaker anion and temperature dependencies with an estimated length-scaleof approximately a nanometer. This length-scale suggests formation of clusters with 2-3 acetamide molecules, signifying local structural heterogeneity as the origin for the micro-heterogeneous nature of these ionic deep eutectics. Some of these results will be presented in this talk, and discussed.