Preface

As joint Chairs of the Faraday Discussion on Dense ionic fluids it gave us great pleasure to welcome experts from across the world to discuss groups of closely related liquid materials that have in common high concentrations of ions.

Looking back at the first two decades of the 21st century, we can see that they began with an intense interest in ionic liquids, defined as being composed entirely of ions when pure. In 2003, Andrew Abbott published his paper on ‘Novel solvent properties of choline chloride/urea mixtures’,¹ the first mention of the now widely researched deep eutectic solvents. Much debate ensued on whether these should be viewed as ionic liquids, often with more heat than light. As the century progressed, it was soon realised that other highly concentrated salt systems, such as water-in-salt solutions in which the molecular compound is the solute and the salt the solvent, were demonstrating interesting and potentially useful properties.² The realisation that these systems had much in common and that there was much to be learned by practitioners working with one of these from their colleagues working with the others, set the scene that led to this Faraday Discussion on Dense ionic fluids.

Claudio Margulis set the tone for the meeting brilliantly with the opening presentation in which he invited us all to engage deeply with the science and each other. Both those who were veterans of the Faraday Discussion format and those new to it took to the task with gusto. We thank everyone who came for their enthusiasm. The closing presentation from Rob Atkin showed, with the good humour that had suffused the meeting, that through the discussions that took place much was indeed learned. We are certain that the cross-fertilisation of ideas that came about will lead to new collaborations, directions of research and enriched understandings of these exciting systems. After all, this is what we hoped to achieve.

We would like to thank all of those involved in the organisation of the meeting. Our scientific committee: Andrew Abbott, Patricia Hunt, Benjamin Rotenberg and Masayoshi Watanabe helped us to put together a diverse and exciting programme. Neave Taylor and Catherine Fung did a fabulous job as our energetic runners with microphones. We were superbly supported throughout the preparation, the event itself and the pulling together of this issue by the amazing Faraday Discussion team at the Royal Society of Chemistry – Katie Ackermann, Catherine Au, Harriet Brewerton and Stuart Govan. We are fully aware that the apparently effortless smooth running of the meeting was, in fact, the result of the hard work and professionalism of the Royal Society of Chemistry staff at Burlington House, who made us feel welcomed and that nothing was too much trouble.

References

1. A. P. Abbott, G. Capper, D. L. Davies, R. K. Rasheed and V. Tambyrajah, Novel solvent properties of choline chloride/urea mixtures, Chem. Commun., 2003, 70–71,  10.1039/B210714G.
2. L. Suo, Y. S. Hu and H. Li, A new class of Solvent-in-Salt electrolyte for high-energy rechargeable metallic lithium batteries, Nat. Commun., 2013, 4, 1481,  DOI:10.1038/ncomms2513.

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