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Durham e-Theses
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Towards responsive lanthanide probes for detection of reactive oxygen species

Richardson, Siobhan (2008) Towards responsive lanthanide probes for detection of reactive oxygen species. Masters thesis, Durham University.



The lanthanide emissive state can be quenched by electron/charge transfer from electron rich donors, resulting in a reduction of both emissive intensity and lifetime. The quenching of luminescence by electron rich donors was further studied in an attempt to derive a feasible mechanism for the quenching process. Additional studies were performed on urate, ascorbate and series of catechols, involving ionic strength variation and extended range Stem-Volmer plots. As a result of these and further studies, a model was proposed for the quenching process; based upon the formation of a long-lived 'exciplex'.In the proposal to synthesise complexes incorporating an intramolecular quenching moiety, two complexes have been synthesised. These complexes incorporate a tetraazatriphenylene chromophore and a methylene-protected catechol positioned trans in the cyclen ring system. Lifetime studies on these complexes show a reduction of 35% for the Eu system (from 1.08 ms to 0.69 ms), and 70% for the Tb system (1.46 ms to 0.47 ms) with respect to analogous complexes. The difference in susceptibility of europium (III) and terbium (III) to quenching affords a promising basis for the development of a ratiometric probe. A two-electron photoreduction was also unexpectedly observed for the Tb complex, where the bipyridyl ring imdergoes irreversible reduction, confirmed by solvent deuteration and MSMS studies.

Item Type:Thesis (Masters)
Award:Master of Science
Thesis Date:2008
Copyright:Copyright of this thesis is held by the author
Deposited On:08 Sep 2011 18:28

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