The research interests of the group encompass a broad range of topics including synthetic coordination and organometallic chemistry as well as materials science. Applications being addressed through this research include catalysis, medical imaging, sensing and platform chemicals from renewable sources.
Some current areas of investigation are outlined below:
Research on gold nanoparticles has enjoyed rapid growth over the last decade in the field of materials chemistry and, increasingly, in bioscience. We are investigating new ways of attaching metal complexes to the surface of gold nanoparticles in order to perform catalytic transformations and sense for anions electrochemically. These materials can be treated in many ways as molecular compounds (solution NMR, IR, electrochemistry) yet offer a means to perform chemistry on a pre-organised surface of great surface area. Computational studies on these systems are being performed in collaboration with Prof. Fernando Bresme (Imperial Chemistry). We are also exploring magnetic nanoparticles with catalytic surface units and their application to 'click' chemistry in collaboration with Dr Silvia Diez-Gonzalez (Imperial Chemistry). This later work was an on a cover of Chemical Communications.
J. D. E. T. Wilton-Ely, Dalton Trans. 2008, 25; E. R. Knight, A. R. Cowley, G. Hogarth, J. D. E. T. Wilton-Ely, Dalton Trans. 2009, 607; E. R. Knight, N. H. Leung, A. L. Thompson, G. Hogarth, J. D. E. T. Wilton-Ely, Inorg. Chem. 2009, 48, 3866; E. R. Knight, N. H. Leung, Y. H. Lin, A. R. Cowley, D. J. Watkin, A. L. Thompson, G. Hogarth, J. D. E. T. Wilton-Ely, Dalton Trans. 2009, 3688; S. Naeem, A. Ribes, A. J. P. White, M. N. Haque, K. B. Holt, J. D. E. T. Wilton-Ely, Inorg. Chem. 2013, 52, 4700; J.-M. Collinson, J. D. E. T. Wilton-Ely, S. Diez-Gonzalez, Chem. Commun. 2013, 49, 11358; S. Naeem, S. Serapian, A. Toscani, A. J. P. White, G. Hogarth, J. D. E. T. Wilton-Ely, Inorg. Chem. 2014, 53, 2404; V. L. Hurtubise, J. McArdle, S. Naeem, A. Toscani, A. J. P. White, N. J. Long, J. D. E. T. Wilton-Ely, Inorg. Chem., 2014, 53, 11740; J.-M. Collinson, J. D. E. T. Wilton-Ely, S. Díez-González, Catal. Comm., 2016, 87, 78; J. A. Robson, F. Gonzalez de Rivera, K. A. Jantan, M. N. Wenzel, A. J. P. White, O. Rossell, J. D. E. T. Wilton-Ely, Inorg. Chem., 2016, 55, 12982; J.-M. Collinson, J. D. E. T. Wilton-Ely, S. Diez-Gonzalez, Catal. Commun. 2016, 87, 78.
Twenty years after the discovery that solutions of thiols organise themselves into Self-Assembled Monolayers (SAMs) on gold, these materials remain at the forefront of nanotechnology applications such as molecular electronics, (bio)sensors and catalytic supports. However, the quality of the monolayers formed can often be low with many defects and small domain sizes. As part of a collaborative project with Prof. Manfred Buck at the University of St. Andrews and Dr Piotr Cyganik in Krakow, we are preparing new, functionalised thiols that form highly regular monolayers suitable for electronic applications.
P. Cyganik, M. Buck, J. D. E. T. Wilton-Ely, C. Woell, J. Phys. Chem. B 2005, 109, 10902; P . Cyganik, M. Buck, T . Strunskus, A. Shaporenko, J. D . E. T. Wilton-Ely, M. Z harnikov, C. Woell, J. Am. Chem. Soc. 2006, 128, 13868; C. Shen, M. Buck, J. D. E. T. Wilton-Ely, T. Weidner, M. Zharnikov, Langmuir 2008, 24, 6609.
Hydrogen bonds are of similar energy (15 - 30 KJ/mol) to the gold-gold contacts observed in many solid state structures of monovalent gold complexes. We are seeking to combine aurophilic and hydrogen bonding in the construction of supramolecular networks as shown in the tetramer below, held together by both types of interactions.
Dithiocarbamates form complexes with all the transition metals. We are currently developing methods of creating extended multimetallic arrays through bridging bis(dithiocarbamate) ligands in conjunction with Dr Graeme Hogarth at King's College London. The electrochemical properties of the arrays achieved are being investigated as well as their use as precursors for new materials through chemical vapour deposition. The example on the right shows an octahedral ruthenium centre attached to a square planar palladium unit.
J. D. E. T. Wilton-Ely, A. Schier, N. W. Mitzel and H. Schmidbaur, J. Chem Soc., Dalton Trans., 2001, 1058; J. D. E. T. Wilton-Ely, D. Solanki, G. Hogarth, Eur. J. Inorg. Chem. 2005, 4027; J. D. E. T. Wilton-Ely, D. Solanki, E. R. Knight, K. B. Holt, A. L. Thompson, G. Hogarth, Inorg. Chem. 2008, 47, 9642; M. J. Macgregor, G. Hogarth, A. L. Thompson, J. D. E. T. Wilton-Ely, Organometallics 2009, 28, 197; E. R. Knight, N. H. Leung, A. L. Thompson, G. Hogarth, J. D. E. T. Wilton-Ely, Inorg. Chem. 2009, 48, 3866; E. R. Knight, N. H. Leung, Y. H. Lin, A. R. Cowley, D. J. Watkin, A. L. Thompson, G. Hogarth, J. D. E. T. Wilton-Ely, Dalton Trans. 2009, 3688; K. Oliver, A. J. P. White, G. Hogarth, J. D. E. T. Wilton-Ely, Dalton Trans., 2011, 40, 5852; S. Naeem, A. Ribes, A. J. P. White, M. N. Haque, K. B. Holt, J. D. E. T. Wilton-Ely, Inorg. Chem. 2013, 52, 4700; Y. H. Lin, L. Duclaux, F. Gonzàlez de Rivera, A. L. Thompson, J. D. E. T. Wilton-Ely, Eur. J. Inorg. Chem. 2014, 2065-2072; V. L. Hurtubise, J. M. McArdle, S. Naeem, A. Toscani, A. J. P. White, N. J. Long, J. D. E. T. Wilton-Ely, Inorg. Chem. 2014, 53, 11740-11748; A. Toscani, E. K. Heliovaara, J. B. Hena, A. J. P. White, J. D. E. T. Wilton-Ely, Organometallics 2015, 34, 494-505; R. Sherwood, F. Gonzàlez de Rivera, J. H. Wan, Q. Zhang, A. J. P. White, O. Rossell, G. Hogarth, J. D. E. T. Wilton-Ely, Inorg. Chem., 2015, 54, 4222; J. A. Robson, F. Gonzalez de Rivera, K. A. Jantan, M. N. Wenzel, A. J. P. White, O. Rossell, J. D. E. T. Wilton-Ely, Inorg. Chem., 2016, 55, 12982; A. Toscani, K. A. Jantan, J. B. Hena, J. A. Robson, E. J. Parmenter, V. Fiorini, A. J. P. White, S. Stagni, J. D. E. T. Wilton-Ely, Dalton Trans., 2017, 46, 5558.
Molecular and nanoparticle-based imaging and therapy
Multifunctional MRI contrast agents
In collaboration with Prof. Tony Cass (Imperial Chemistry) and Prof. Rene Botnar (St. Thomas' Hospital, KCL), we are designing new magnetic resonance imaging (MRI) contrast agents. MRI is a powerful, non invasive technique used to diagnose disease in patients. Improvement to the contrast of the images is achieved using paramagnetic (but toxic) gadolinium(III) ions. Two approaches using Gd(III) are being employed to develop more efficient and targeted contrast agents. The first involves the construction of assemblies with three Gd(III) ions connected to a central transition metal node, which can be also be used to introduce a second imaging modality (optical, PET) into the system. An alternative approach, based on the same methodology, is the functionalisation of gold nanoparticles with Gd(III) units. The control over the size and surface units of these nanoparticles allow greater targeting of the agent, potentially allowing lower doses to be employed. We are currently working with Dr Dan Elson (Imperial, Department of Surgery and Cancer) to add a photo-switchable therapeutic action to these materials.
S. Sung, H. Holmes, L. Wainwright, A. Toscani, G. J. Stasiuk, A. J. P. White, J. D. Bell, J. D. E. T. Wilton-Ely, Inorg. Chem. 2014, 53, 1989
M. Rasekh, Z. Ahmad, R. Cross, J. Hernandez-Gil, J. D. E. T. Wilton-Ely, P. W. Miller, Mol. Pharmaceutics, 2017, 14, 2010-2023
Imaging and sensing using dual modality fluorescent PET imaging probes
Positron Emission Tomography (PET) is a powerful technique, used particularly in oncology, which allows three-dimensional imaging of tissue deep in the body (2 million scans in the US each year). However, substantial infrastructure is required for (often short-lived) radioisotope generation. Together with Prof. Tony Gee (St. Thomas' Hospital, KCL) We are working to incorporate fluorescence within the same agent in order to allow imaging through the emission of visible light to indicate the location of the agent. Adding targeting units to the probe ensures high selectivity for tumours, thus creating a targeted, dual modality agent for the imaging of cancer. Importantly, this will allow visualisation of the tumour site before an invasive procedure (using PET) and, once radiation is no longer present, during surgery (using the fluorescence).
It has only recently been established that our bodies naturally produce and use carbon monoxide as a gaseous messenger. Using a fluorescence response, similar probes to those above are being investigated for the real-time monitoring of carbon monoxide in this role. Based on related systems we have developed (J. Am. Chem. Soc. 2014, 136, 11930, J. Am. Chem. Soc., 2017, DOI: 10.1021/jacs.7b11158), such systems could solve the problems of low sensitivity and response speed which undermine current approaches in this new field. In addition, the presence of abnormal levels of endogenous carbon monoxide has been shown to be a marker of disease, providing clinical relevance.
See also: KCL-IC Centre for Doctoral Training in Medical Imaging and MRC Clinical Sciences Centre
Breakdown and conversion of biomass using ILs
Also under investigation, in collaboration with Dr Jason Hallett, (Imperial Chemical Engineering), is the dissolution and breakdown of woody biomass using transition metal catalysts in ionic liquids. Ionic liquids are solvents which can be tuned to possess specific properties and they are exceptionally good at dissolving the cellulosic component of biomass. We have used them to develop a process to dissolve refined biomass (fructose, glucose and cellulose) and convert it to 5-hydroxymethylfurfural (5-HMF) in high yield using low catalyst loadings. 5-HMF has been identified as a key platform chemical which could be used as an alternative to petroleum-sourced building blocks in the future. We are investigating its transformation into other useful building blocks such as monomers for polymerisation. This work is being sponsored by the Climate-KIC initiative. Our recent paper was also chosen as an ACS Editor's choice article and featured as the cover image of the journal.
S. Eminov, J. D. E. T. Wilton-Ely, J. P. Hallett, ACS Sustainable Chem. Eng. 2014, 2, 978; S. Eminov, A. Brandt, J. D. E. T. Wilton-Ely, J. P. Hallett, PLoS One, 2016, 11, e0163835; S. Eminov, P. Filippousi, A. Brandt, J. D. E. T. Wilton-Ely, J. P. Hallett, Inorganics, 2016, 4, 32.
Sensing of carbon monoxide and heavy metals
In collaboration with the group of Prof. Ramon Martinez-Manez (UP Valencia, Spain), we are using transition metal complexes to sense low levels of carbon monoxide in the solids state. This can be achieved through a dramatic colour change as well as an increase in fluorescence. Importantly, the complexes are designed to be selective for carbon monoxide over other species which may be present such as water, carbon dioxide etc. The application of this approach to the sensing of endogenous CO produced in vivo as a messenger molecule has also been achieved.
M. E. Moragues, A. Toscani, F. Sancenon, R. Martinez-Manez, A. J. P. White, J. D. E. T. Wilton-Ely, J. Am. Chem. Soc. 2014, 136, 11930.
A. Toscani, C. Marin-Hernandez, M. E. Moragues, F. Sancenon, P. Dingwall, N. J. Brown, R. Martinez-Manez, A. J. P. White, J. D. E. T. Wilton-Ely, Chem. Eur. J. 2015, 21, 14529.
A. Toscani, C. Marín-Hernández, F. Sancenón, R. Martínez-Máñez, J. D. E. T. Wilton-Ely, Chem. Commun., 2016, 52, 5902 (cover article).
C. de la Torre, A. Toscani, C. Marín-Hernández, J. A . Robson, M. C. Terencio, A. J. P. White, M. J. Alcaraz, J. D. E. T. Wilton-Ely, R. Martínez-Máñez, F. Sancenón, J. Am. Chem. Soc., 2017, DOI: 10.1021/jacs.7b11158
The presence of heavy metals in aqueous solution is of enormous concern and so their detection at very low levels is of great importance. We collaborate with Prof. Joshua Edel and Prof. Alexei Kornyshev (both Imperial Chemistry) to achieve the selective detection of mercury ions at very low concentrations using functionalised gold nanoparticles and Surface Enhanced Raman Spectroscopy.
M. P. Cecchini, V. A. Turek, A. Demetriadou, G. J. Britovsek, T. Welton, A. Kornyshev, J. D. E. T. Wilton-Ely, J. B. Edel, Adv. Optical Mater. 2014, 2, 966 (cover article).
NHC-derived dithiocarboxylate ligands
A major theme in the group is sulphur ligands and a new avenue of research has been initiated recently in collaboration with Prof. Lionel Delaude, University of Liege, Belgium. N-heterocylic carbenes have become powerful ligands in their own right but they can also be used to form zwitterionic ligand systems of the form NHC.C(A)S where A = O, C, NR. We have been exploring the reactivity of these ligands with ruthenium, palladium and gold and are now optimising their use as ligands to support catalytic oxidative C-H functionalisation.
S. Naeem, A. L. Thompson, L. Delaude, J. D. E. T. Wilton-Ely, Chem. Eur. J. 2010, 16, 10971; S. Naeem, L. Delaude, A. J. P. White, J. D. E. T. Wilton-Ely Inorg. Chem. 2010, 49, 1784; S. Naeem, A. L. Thompson, A. J. P. White, L. Delaude, J. D. E. T. Wilton-Ely, Dalton Trans. 2011, 40, 3737; E. Y. Chia, S. Naeem, A. J. P. White, L. Delaude, J. D. E. T. Wilton-Ely, Dalton Trans. 2011, 40, 6645; M. J. D. Champion, R. Solanki, L. Delaude, A. J. P. White, J. D. E. T. Wilton-Ely, Dalton Trans. 2012, 41, 12386
Recovery and re-use of metals in catalysis
Precious metals such as Rh, Pd, Pt, Au underpin a vast range of technological processes. They are obtained using often environmentally-damaging mining processes, which have substantial impact on the local communities. The existing deposits are located in particular countries and their supply and price can often be compromised by geopolitical events. These factors have placed increasing pressure on the traditional sources of precious metals. One way to counter this is to recycle and re-use these metals from secondary sources such as automotive scrap and electrical and electronic waste (WEEE).
We have very recently started a new collaboration with Professor Angela Serpe at the University of Cagliari in Sardinia, Italy, who is an expert on recovering metals from waste using mild often sulfur-based ligands. Together with students from the MRes in Green Chemistry and MRes in Catalysis courses, we are working on applying directly in catalysis the molecular metal complexes produced by the patented process pioneered by Professor Serpe, which is now in the pilot plant stage.
We have recently shown how molecular palladium complexes can be recovered selectively from used automotive catalytic converters and be directly valorised as highly-active catalysts for C-H oxidative functionalisation reactions. This avoids the high energy cost of passing through palladium metal or its salts, thus creating homogenous catalysts from used heterogeneous catalysts. This approach combines many fundamental concepts of green chemistry through the use of safe reagents and mild conditions to recover and re-use metals for use in a catalytic transformation. This fits very well to the ‘circular economy’ concept, which seeks the best means of valorising the output of a recovery process.
K. A. Jantan, C. Y. Kwok, K. W. Chan, L. Marchio, A. J. P. White, P. Deplano, A. Serpe, J. D. E. T. Wilton-Ely, Green Chem., 2017, 19, 5846-5853.