Stephen J Osborne

PhD Student

Stephen

DBB.XX.XXX
+44 (0) 28 9097XXXX
sosborne03@qub.ac.uk

PhD Project:


The First Porous Ionic Liquids


Supervisors

Prof Jorge Kohanoff Prof Stuart James (Chemistry, QUB) Dr Gareth Tribello Dr Mario del Pópolo (UNCuyo, Mendoza, Argentina)

Interests

  • Ionic liquids
  • Inorganic Chemistry
  • Porosity in the liquid state
  • Gas physisorption
  • Code development

Most Recent Publication

Thermochromism and switchable paramagnetism of cobalt(II) in thiocyanate ionic liquids, Dalton Transactions, 2015, 44, No. 25, pp. 11286
doi: 10.1039/C5DT01829C Abstract
Temperature-dependent switching of paramagnetism of a cobalt(II) complex is observed in an ionic liquid solution. Paramagnetic and thermochromic switching occur simultaneously due to a reversible change in coordination. This reversible switching is possible in the ionic liquid solution, which enables mobility of thiocyanate anions by remaining mobile at low temperatures and acts as an anion reservoir.

All of Stephen's publications

Holey Liquids

Solid-state porosity is very common in the world around us, from the construction of buildings to biology and of course the bathroom sponge. In chemistry, solid frameworks such as Metal Organic Frameworks (MOFs), Covalent Organic Frameworks (COFs) and Zeolites have been a focus for research for many years now. These frameworks normally form a cavity into which a small molecule could be absorbed. This internal cavity makes these materials good candidates for research into gas separation and storage. While solids are likely better for gas absorption they still have a distinct disadvantage, they do not move. While at first glance this immobility appears to be a mute point, if you want to form a flow process this could be a sticking point as MOFs, COFs and zeolites are solid until high temperatures.

Types of porous liquid
Figure 1: Catagories of Porous Liquid

In 2007, O’Reilly et al. published a concept article outlining their basis of what a porous liquid would be and how it could be defined. In this article they defined three categories of porous liquid; neat (Type 1), an empty host in a molecular solvent (Type 2) and a framework dispersed within a sterically hindered solvent (Type 3). A caroon schematic of this can be seen in figure 1. A few years later Melaugh and Giri in a collaborative computational/experimental study at Queen’s University Belfast studied the potential of a COF first reported by Cooper et al. to form a porous liquid. The computational part of the study showed medium length alkyl tails on the Cooper cages gave an acceptable balance of cage penetration and gas absorption. In the real world the alkyl cages although synthetically possible, proved to be near impossible to dissolve in traditional solvents and were only liquid above room temperature. This leadto the development of cages with crown ether functionality in place of the alkyl groups allowing studies of the cages to be carried out in crown ether solvents. For methane it was shown that the ethereal type 2 system formed by the alkylated cage and 15-crown-5 ether, increased gas absorption by ten times over the neat crown ether as seen in figure 2 below.

Proof of concept
Figure 2: Proof of concept work by N. Giri, G. Melaugh, M. del Popólo and S. James. With thanks to M. Costa Gommes for methane absorption data

While further work is required upon these non-ionic systems both experimentally and computationally, thoughts have turned towards utilising ionic liquids. Ionic liquids already have an extensive body of research into their ability to absorb and separate gases, notably carbon dioxide. While a truly ionic cage would be both an ideal and a true type one porous ionic liquid, synthetically it is a daunting task. Therefore to start with it would be desirable to take advantage of the wide range of ionic liquids available and their well-documented solvent properties. These solvent properties can be exploited to dissolve these porous cages inside that are insoluble in traditional solvents to form a type 2 porous ionic liquid. This study is a collaborative work between the Atomistic Simulation Centre and the School of Chemistry and Chemical Engineering at Queen’s University Belfast, and will consist of both experimental and computation studies to form the first porous ionic liquids.