Towards Novel Optical Sensors

Smith, Graeme (2000) Towards Novel Optical Sensors. MSc(R) thesis, University of Glasgow.

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Abstract

This research presented in this thesis is based in the development of optical sensors. More specifically, this project outlines two novel systems that could possible used within this field. The first system is based on a functionalized ruthenium(II) polypyridyl complex and the second is based on derivatives of merocyanine 540. For the first system the synthesis and detailed photophysical properties of a bis(N-methylene-4-pyridinium-4'-pyridine) functionalized ruthenium(II) polypyridyl complex (C2) in solvents of varying polarity and Gutmann's donor number (DN) are discussed. The emission spectrum of (C2) in varying solvents was also simulated and parameters including the Huang-Rhys (Sm) obtained. Respectable correlations of the optical properties of (C2) with the solvent polarity factor (Af) and DN were obtained. These results were used to calculate a difference in dipole moment between ground and excited state of ca 10 D, and propose a simplified potential-energy surface model to explain the results. The excited state lifetime data for (C2) in acetonitrile were collected over a modest temperature range of 60K. The Arrhenius plot of In (kobs) vs 1/T was found to be linear affording a proportionately low activation energy of 5.6 (+/- 0.2) kJ mol-1 when compared to the literature value of 45.5 kJ mol-1 for [Ru(biby)3]2+. For the second system the design of novel merocyanine dyes for use in sensing and photodynamic therapy is given. The parent dye of these molecules being merocyanine 540. With its preferential uptake into leukaemia cells and their subsequent eradication by induced photosensitization, has rewarded it considerable interest over the years in the field of photodynamic therapy. Its ability to act as a photosensitizer depends greatly on its efficiency of intersystem crossing to the triplet manifold. Unfortunately the dominant photoprocess involves photo-isomerization to form a long-lived (unstable) isomer. It is expected that if this isomerization process could be prevented then it would lead to a much more potent photosensitizer. There have been extensive studies into the prevention of this process ranging from structural to electronic changes within the molecule, but sadly to no avail. The design of the derivatives MC1 and MC2 was carried out via the incorporation of a triazamacrocycle into the structure of the molecule. It is predicted that with the binding of a metal to this macrocycle the molecule will be locked into the trans isomer and be unable to undergo photo-isomerization.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Adviser: Andy Benniston
Keywords: Physical chemistry, Organic chemistry
Date of Award: 2000
Depositing User: Enlighten Team
Unique ID: glathesis:2000-76014
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 17:07
Last Modified: 19 Nov 2019 17:07
URI: http://theses.gla.ac.uk/id/eprint/76014

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