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Modern mass spectrometry investigations into the gas-phase behaviour of derivatised fullerenes and amino acid supported silver clusters

By Leanne Claire Nye


A variety of mass spectrometry experiments have been performed with the aim of further understanding of the ionisation processes involved and the gas-phase behaviour of various organic molecules within two ionisation techniques: Matrix-Assisted Laser Desorption Ionisation (MALDI) and Electrospray Ionisation (ESI). The majority of the studied compounds were C60 derivatised in various ways, either with addition of a ligand, or by the creation of an orifice within the cage structure with heteroatoms – Open-Cage Fullerenes (OCFs). The DCTB-MALDI investigations into the OCFs revealed a possible correlation between orifice size and the heteroatoms present in the orifice, to how the OCF behaved under elevated laser fluence. An extended investigation into the smallest hydrofullerene, C60H2, established for the first time decomposition-free conditions for its analysis, so that its oxidation over time, which has been controversial in the literature, could be studied. \ud The use of pencil lead as a matrix was compared to the traditional matrix for fullerenes, DCTB. Pencil lead was found to be inferior as a matrix, however, proved an exceptionally easy way of creating sodium and potassium adducts, which was found to be useful in the differentiation of isomers of some of the OCFs. The formation of polyaromatic hydrocarbons adducts to C60 were synthesized and analysed with both MALDI and ESI-MS. These complexes are notoriously labile, yet a larger C60PAH:C60 peak intensity ratio was achieved than had been previously reported. \ud The use of silver in ESI experiments was explored in depth. Initially, heterodimers of amino acids bound by silver (I) ions were created and fragmented in order to ascertain relative silver binding affinities, by use of the kinetic method. The same technique was applied to compounds that have been traditionally difficult to ionise with ESI-MS. These included pure fullerenes, fullerene derivatives, and various fullerene precursors. These compounds have been successfully arranged into order of their silver-ion affinities

Topics: QD
OAI identifier: oai:wrap.warwick.ac.uk:2783

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