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Title: Rational development of a turn-on fluorescent sensor for hydrogen peroxide
Author: Morris, Graeme
ISNI:       0000 0004 7962 9839
Awarding Body: University of the West of Scotland
Current Institution: University of the West of Scotland
Date of Award: 2017
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Electron transfer reactions are fundamental chemical processes that are crucial within the chemical and biological sciences, making the understanding of them of utmost importance. Therefore, bimolecular pairings of triarylphosphines and fluorescent diketopyrrolopyrroles (DPP) were studied to examine the less commonly investigated electron transfer processes present for the row three element phosphorus. It was found that exergonic pairings followed Marcus theory of electron transfer, whereas endergonic pairings were determined to exhibit a bonded exciplex mediated charge transfer quenching mechanism. Hydrogen peroxide is an important marker for oxidative stress in biological systems, which is a key process in multiple vital systems and also in several degenerative systems. Spatial and temporal detection of hydrogen peroxide by visual means is therefore an important area to explore. This work has designed and produced a novel, unimolecular turn-on fluorescent DPP sensor for hydrogen peroxide. Biologically relevant sensitivity down to low micromolar concentrations was observed in benchmark acetonitrile solution experiments. Organic fluorine is known for its large electronegativity and was therefore introduced as a viable route to decreasing the electron density of the DPP moiety to make it a better electron acceptor; molecular modelling studies predicted this to produce enhanced quenching systems. Organic fluorine is also known to be involved in several close contact interactions in crystalline systems, which can therefore affect the crystal organisation. A series of systematically substituted DPPs were designed, and the effects of fluorine shown to produce unique and previously unobserved crystal packing configurations that presented interesting discoveries for those in the area of charge mediating molecules for uses within optoelectronic devices. The changes to intermolecular interactions and charge transfer properties of N-benzyl DPPs have previously been investigated through small, systematic structural variations. A study into improving these interactions by extension of the π-conjugated DPP system is investigated here and shown to improve the properties of the π-π dimer stacking pairs responsible for the emergence of charge mediating semi-conductor bands.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available