Research
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A Wordle word cloud, made from the text of my Discovery Grant (in UVic colours)
Research
We're inorganic chemists who discover and
make new catalysts. We use electrospray
ionization mass spectrometry as a rapid investigative
tool to probe systems intractable to other approaches.
Further details are given below; also see our
list of
Catalyst Discovery
We use our designer ligands and methodological developments to help us study catalytic reactions. We have work in progress on systems as diverse as biodiesel synthesis, activators for olefin polymerization, palladium-catalyzed cross-coupling reactions, platinum-catalyzed hydrosilylation, and rhodium-catalyzed hydrogenation. Contact Scott for more details of current projects.
An "electrospray active" version of a distannoxane, the proposed catalyst for (trans)esterification of waste oil into biodiesel. [57]
Ligand Design
We are interested in reactions catalysed by transition metal complexes, with a particular interest in those that are charged [51]. We design ligands for this express purpose [43, 56, 58]. The resulting charged complexes are of particular interest as they are suitable for use in green reaction media (such as water or ionic liquids) [32] and have the advantage of being amenable to study using ESI-MS [27].
An "electrospray active" phosphine ligand, equipped with a charged phosphonium group [58].
Methodology development
The group uses electrospray ionization (ESI) tandem mass spectrometry (MS/MS) as its primary characterization tool, and we operate a high performance hybrid quadrupole/time-of-flight instrument. Primarily used for the study of high-mass biological molecules, ESI-MS is a powerful and sensitive technique capable of rapidly characterising complex mixtures at very low concentration [10, 13, 18]. As such, it's a great tool for in situ studies of catalysis in action - but it has weaknesses that we've had to address. We've shown we can spray non-polar solvents [42], blur the distinction between gas and solution phase [48, 50], study catalysts in ionic liquids [29, 34], do ESI-MS under oxygen- and moisture-free conditions [52], and developed a way to reduce the large quantities of structural data obtained from MS studies to a manageable size in a visually attractive and intuitive way [9, 17, 30].
ESI mass spectrum of a rhodium catalyst and an ionic liquid, from a hexane solution [42].
Tools of the trade: hexapole ion focusing devices, part of the front end of the spectrometer.
Energy-Dependent Mass Spectrometry
EDESI-MS is a data presentation technique we Essentially, fragmentation energy is ramped up across the full range and the results displayed as a 2D projection of a 3D surface. When applied to metal clusters, all the neutral ligands may be stripped away, generating a bare metal core [26]. This specific, high-yield approach to cluster synthesis can be used to investigate the gas phase reactivity of nanoscale metal particles. We are also extending the application of EDESI to other classes of compound, including metal complexes, organic compounds and biomolecules [23, 39].
EDESI spectrum of a dianionic metal cluster.
Note the electron autodetachment event at 80 V [19],
and breakup of the metal core at high fragmentation energies.
Gas-phase cluster chemistry
The chemistry of transition metal carbonyl cluster compounds is a continuing interest (see "books" section of the website), including those clusters in the size regime between clusters and colloids [10, 33]. Metal nanoparticles such as these possess a range of interesting properties. Our EDESI work revealed the ease with which naked metal particles could be generated in the gas phase. We are currently exploiting this ability [54].
Metal core structures of some high-nuclearity osmium carbonyl clusters [10].
© JS McIndoe, Department of Chemistry, University of Victoria · Updated 23 October, 2009