Hydrogen Bonding in Ionic Liquids

Abstract

Ionic liquids (ILs) are new solvents and electrolytes, composed of discrete cations and anions. ILs differ from typical salts in that the ions are larger, more diffuse and chemically complex. A key feature of ILs is the ability to tailor the physico-chemical properties by varying the constituent ions. ILs are being explored for an astonishingly wide range of applications, including for use in industry, in energy applications, in technological devices and for health applications. However, advances are being hampered by an inability to predict, or even rationalise, IL properties.

Hydrogen bonding (H-bonding) is present in many ILs and plays a key role in determining the physico-chemical properties. The versatility of ILs is, in-part, due to the diverse range of H-bonding that occurs within ILs. While the general nature of a simple "ordinary" H-bond is well known, a deeper characterisation of even traditional H-bonds is more complex. ILs also exhibit a fundamentally distinct and new type of H-bond, the doubly ionic H-bond, a H-bond between two ions, overshadowed by ionic interactions, but also enhanced by the strong polarization of a charged environment.

Computational (quantum chemical) studies can provide insight into the molecular level interactions within ILs, thus establishing a link between the constituent ions and the resultant physico-chemical properties. In this presentation I will interrogate, through computational methods, the structural, vibrational and electronic characteristics of H-bonds in ILs. I will highlight the non-traditional features of H-bonding exhibited by ILs and explore how to conceptualise H-bonding within ILs.

Biography
Patricia Hunt is Professor of Theoretical and Computational Chemistry in the School of Chemical Physical Sciences at Te Herenga Waka – Victoria University of Wellington (New Zealand). Patricia moved from her previous position as Professor at Imperial College London, UK in 2020. See her group webpage.

Patricia's group undertakes theoretical development and applies computational modelling to address a range of problems and projects within inorganic, materials and bio related chemistry. Primary methods are quantum chemical but her group also employs classical molecular dynamics in a supporting role. Research spans four overlapping areas; liquids & solvation, catalysis & reactivity, bonding and theory & method development. Current areas of research include a wide range of ionic liquids areas (pharmaceuticals, drug delivery, proton-conducting electrolytes, battery electrolytes, IL solvents, and ILs as fuels for ion- drives in mini-satellites). Work on fundamental understanding includes, non-covalent interactions, X-bonding, dispersion interactions, Hydrogen-bonding, and the distribution and transfer of "charge" within molecules and ions.

Mechanistic studies have included Group II catalysis, Frustrated Lewis Acid Base Pairs, and the degradation of chemical warfare agents/toxic chemicals.
Patricia is currently an inaugural NZRS Mana Tūārangi Distinguished Researcher.

She was ranked in the top 0.5% of scholars world-wide in 2024 by ScholarGPS. She has led or been involved in securing the equivalent of over $30 million NZD in competitive research funding. She is the lead for the VUW Hub for Simulation, Numerical methods, Analytics and Programming (VUW-SNAP), and she has been recognised with multiple awards and accolades for her teaching, research supervision and mentoring of early-career researchers.

She has given many plenary or keynote talks at international conferences around the world, including; Ionic Liquids and the Future of Soft Materials(UK), Ionic Liquids Gordon Research Conference (USA), Women in Science Symposium (Germany), International Congress on Ionic Liquids (China), the Sustainable Industrial Processing Summit (Brazil) and has recently been the opening speaker at ASIL11 the Australasian Symposium on Ionic Liquids.