Stable organic radicals and their untapped potential in ionic liquids

Abstract

Stable organic radicals have an open shell structure that makes them suitable for use in a diverse set of applications. Specifically, it is the reversible one-electron redox behaviour that makes these species suitable for energy storage and in molecular electronics. Maintaining chemical stability, low redox potential and charge transfer capabilities, are key to the further development of these materials. To date, researchers have largely focused on the the preparation of new molecules with improved redox capabilities for use in traditional solvents. More recently exploration into the use of ionic liquids to stabilise charged species and reduce side reactions has shown promise. Computational and preliminary experimental studies have explored the impact of ionic liquids on radical stabilisation, and notable improvements have been observed for nitroxide-based materials when traditional solvents are replaced by ionic liquids. However, these gains require significant refinement based on the identity of the radical species and the ionic liquid. In this highlight, we focus on the current state of using ionic liquids as solvents to stabilise organic radicals and suggestions on the future direction of the field.