Polarization versus Temperature in Pyridinium Ionic Liquids

TL;DR

This study investigates how electronic polarization in pyridinium-based ionic liquids varies with temperature, revealing that non-additive interactions remain stable while dipole moments increase due to thermal effects, enhancing understanding of ionic systems.

Contribution

First comprehensive analysis of temperature dependence of electronic polarization in pyridinium ionic liquids using advanced molecular dynamics simulations.

Findings

Non-additivity in cation-anion interactions remains nearly constant between 300 and 900 K.

Average dipole moment increases with temperature due to thermal fluctuations.

Results improve fundamental understanding of electronic effects in ionic liquids.

Abstract

Electronic polarization and charge transfer effects play a crucial role in thermodynamic, structural and transport properties of room-temperature ionic liquids (RTILs). These non-additive interactions constitute a useful tool for tuning physical chemical behavior of RTILs. Polarization and charge transfer generally decay as temperature increases, although their presence should be expected over an entire condensed state temperature range. For the first time, we use three popular pyridinium-based RTILs to investigate temperature dependence of electronic polarization in RTILs. Atom-centered density matrix propagation molecular dynamics, supplemented by a weak coupling to an external bath, is used to simulate the temperature impact on system properties. We show that, quite surprisingly, non-additivity in the cation-anion interactions changes negligibly between 300 and 900 K, while the average dipole moment increases due to thermal fluctuations of geometries. Our results contribute to the fundamental understanding of electronic effects in the condensed phase of ionic systems and foster progress in physical chemistry and engineering.