The research group works mainly with sulphur-based systems, in particular thiols and dithiocarbamates to construct new, often multimetallic, materials suitable for applications in fields as diverse as molecular electronics, (bio)sensing and catalysis. Although the systems range in orders of magnitude (monometallic compounds to gold nanoparticles), the key to our work is our broad expertise in synthetic organic, organometallic and coordination chemistry.
In conjunction with Dr Graeme Hogarth and Dr Katherine Holt at UCL, we have explored the potential of dithiocarbamate ligands to link metal centres together in homo- or heteronuclear systems. The ability to utilise the properties of two or more metals in the same ensemble allows the material to exhibit diverse and complementary reactivity within the same system. This can lead to two metals performing catalysis in tandem or the physiological fate of a cytotoxic unit being traceable due to a luminescent metal-based tag. An extension of the methodology we use to achieve this allows the attachment of a metal unit (chosen for its properties) to be immobilised on the surface of gold nanoparticles (see Figure). The large surface area and pre-organised surface arrangement coupled to the marked difference in physical properties give these materials significant benefits over conventional homogeneous or heterogeneous systems in terms of activity, selectivity and recycling of the material. We are in the process of investigating these functionalised nanoparticles using computational methods with Dr Fernando Bresme. This will allow us to improve their design and determine the relative strength of interactions between the surface and the sulphur units attached with a view to constructing mixed surface topographies.
Although dithiocarbamates have proved effective in the tethering of transition metal units to the surface of the nanoparticles, we are also exploring other methods of adding functionality to nanoparticles through straightforward and reliable organic transformations (e.g., click or metathesis chemistry). The incorporation of the innate properties of the metal core of the nanoparticle, such as magnetism, is also under investigation.
In addition to three dimensional gold surfaces, we are also actively engaged in a collaboration with Dr Manfred Buck at the university of St. Andrews to design biphenylalkane thiols, which can form large, almost defect-free domains on Au(111) surfaces. Functionalisation of the surface functionality will allow the deposition of metal units, which may ultimately lead to the fabrication of surface features functioning as electronic components.
In 2011, a new area of research was initiated in collaboration with Dr Jason Hallett, directed at the breakdown of biomass and its conversion into platform chemicals. This approach employs metal catalysts in ionic liquids to dissolve the cellulosic component of biomass and convert it catalytically into 5-hydroxymethylfurfural (5-HMF) – a versatile starting point for many chemical building blocks. This approach could provide a non-petrochemical source for many of the fundamental compounds on which the chemical industry depends.
The use of imidazolium-2-dithiocarboxylates in the formation of gold(I) complexes and gold nanoparticles. S.Naeem, L. Delaude, A. J. P. White, J. D. E. T. Wilton-Ely Inorg. Chem., 2010, 49, 1784-1793 [doi: 10.1021/ic9021504]
Multimetallic arrays: Bi-, tri-, tetra- and hexametallic complexes based on gold(I) and gold(III) and the surface functionalisation of gold nanoparticles with transition metals. E. R. Knight, N. H. Leung, A. L. Thompson, G. Hogarth, J. D. E. T. Wilton-Ely, Inorg. Chem., 2009, 48, 3866-3874 [doi: 10.1021/ic802442d]
Bifunctional dithiocarbamates: a bridge between coordination chemistry and nanoscale materials
E. R. Knight, A. R. Cowley, G. Hogarth, J. D. E. T. Wilton-Ely, Dalton Trans., 2009, 607-608 [doi: 10.1039/b821947h]
The surface functionalisation of gold nanoparticles with metal complexes
J. D. E. T. Wilton-Ely, Dalton Trans., 2008, 25-29 [doi: 10.1039/b714144k]
On the importance of purity for the formation of self-assembled monolayers from thiocyanates
C. Shen, M. Buck, J. D.E.T Wilton-Ely, T. Weidner, M. Zharnikov, Langmuir, 2008, 24, 6609-6615 [doi: 10.1021/la8004272]
Competition as a design concept: Polymorphism in self-assembled monolayers of biphenyl-based thiols P. Cyganik, M. Buck, T. Strunskus, A. Shaporenko, J. D. E. T. Wilton-Ely, M. Zharnikov, C. Wöll, J. Am. Chem. Soc., 2006, 128, 13868-13878 [doi: 10.1021/ja0640647]