Dr Ewan Clark completed his MSci at the University of Cambridge in 2004, working with Dr Alex Hopkins on the synthetic organic applications of silyl anions. He remained in Cambridge for his PhD, this time with Professor Jeremy Rawson (now at the University of Windsor), working on developing new, modular synthetic routes to sulphur/nitrogen heterocyclic systems and their co-ordination chemistry with first row transition metals.
After submitting his thesis in 2008, Ewan moved to Newcastle University for a post-doctoral position with Dr Keith Izod where he worked on low-valent, heavy tetrelynes (the Ge(II) and Sn(II) analogues of more conventional carbenes) and their stabilisation by donor-functionalised phosphanide ligands. In 2011 he took up a second post-doctoral position with Dr Michael Ingleson at the University of Manchester to study the incorporation of novel main group borocation and carbocation Lewis acids into Frustrated Lewis Pairs for small molecule and sigma-bond activation. Ewan joined the School of Physical Sciences at Kent in 2014, taking the position of Lecturer in Chemistry.
Dr Ewan Clark’s research interests lie in uncovering and exploiting the properties, both chemical and material, of main group elements with unconventional oxidation states or charges. In particular, the majority of conventional open shell (ie radical) chemistry or chemistry involving well-defined redox cycles is performed using transition metals whose multiple stable oxidation states and core-like valence orbitals predispose them for these functions. Nevertheless, this chemistry is not unique to the transition metals and opening up the analogous p-block chemistry will develop not only new and complementary applications, but also show hitherto unobserved properties.
The group expertise lies in the synthesis and handling of highly reactive compounds using inert atmosphere techniques and their characterisation in both solid state and solution by diffraction and spectroscopic methods. These studies are then coupled with computational studies to derive complete structure-property relationships which in turn allow both a deeper understanding of the fundamental behaviour of the systems and form an iterative feedback loop to design and deliver compounds with tailored properties. Current research topics are focused towards phosphorus chemistry and include the following.
Stable, neutral main-group radicals have been known for many years, dating back to 1900 when Gomberg first isolated and identified the C(III) radical which now bears his name. Since then, many more classes have been discovered but these are primarily derived from the top right of the periodic table, using the lighter elements. As the periodic table is descended, the number of radicals falls off dramatically, and there are only a handful of structurally characterised phosphorus radicals known. Incorporating heavier elements into radical systems has a dramatic effect on their properties, as the more radially diffuse orbitals of the heavier element allow a greater array of interactions in the solid state or in aggregated species. Work is focused on developing new P(II) and P(IV) radicals, and their heavier congeners, both as materials in their own right and for use as ligands to transition metals to generate clusters with combined metal-radical magnetic properties.
Isoelectronic applications of cationic fragments for fluorescent materials
The isoelectronic analogy is a potent tool in synthetic chemistry as it allows many properties to be conserved (shape chief among them) while allowing the tailoring of others when developing derivatives. The [RP(III)]+ fragment is isoelectronic to [R2B], a ubiquitous moiety in fluorescent materials used to both tailor band gaps and impart structural rigidity and thus increase fluorescence quantum yields. The incorporation of a heavier element is predicted to decrease the bandgap relative to the analogous boron system, and thus give red-shifted emission and absorption spectra, crucial for applications in biomedical imaging and in light-harvesting for optoelectronic purposes, while the positive charge will result in different solubility profiles and solid-state aggregation which will diversify options in device manufacture techniques.
Dr Clark teaches inorganic and physical chemistry across all stages of the programme and runs undergraduate projects for those interested in catalysis, method development, and main group synthesis.