Quan, Wen-Dong (2016) The design, construction and characterisation of self-assembled biomimetic multi-chromophoric photosystems. PhD thesis, University of Warwick.

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Abstract

The potential of a maleimide based fluorophore as well as the utilisation of simple methodologies to produce synthetic mimics of natural light harvesting complex (LHC) were explored.

In Chapter 1, the inspiration for the current work is discussed, followed by a brief guide for the interpretation of the work presented in subsequent chapters. Finally, the ultimate aim and concept for the thesis is detailed. The general instruments and methodologies applicable to all experiments conducted are then described in Chapter 2.

Chapter 3 presents the first set of results from the thesis work. This work focused on unravelling the previously unexplained fluorescence quenching observed in maleimide based fluorophores in protic solvent. This was achieved through the use of computational chemistry, ultrafast spectroscopy and synthetic chemistry. The work identified a photochemical process, in the form of electron driven proton transfer, as the fluorescence quenching mechanism. Such understandings should provide a much needed insight towards future designs of maleimide based fluorophores that fully realise the potential of this class of photoactive pigments.

This was then followed by the attempt to produce the platform for which inter-chromophoric assemblies could occur in aqueous media, documented in Chapter 4. The main body of the work involved the selection of the most effective synthetic method readily reported in the literature: the synthesis of functionalised porphyrin through the condensation reaction between dipyrrolemethane and functionalised aldehyde; and the conjugation between porphyrin and polymers with the copper catalysed alkyne-azide cyclo addition click reaction. The resulting platform was successfully demonstrated to be capable of self-assembly, without the need of covalently linking the chromophores to one another. Furthermore, and most importantly, the photophysical properties of these chromophores were largely retained in the assembled structure. The results presented could lead to a new class of photoactive nanostructures that closely mimic natural LHCs, in which the properties of individual chromophores could be fully exploited and assembled without the need of covalent linkage.

The potential of using the platform documented in Chapter 4 to produce functional natural LHC mimics was then explored in the final results chapter, Chapter 5, where a pseudo reaction centre (RC) was introduced. The spectroscopic experiments demonstrated that the photodynamics of the assembly was significantly altered in the presence of the RC. This was proposed to be based on a push-pull mechanism facilitated by the presence of metal to N donor coordinated complex. Furthermore, the N donor in the chosen RC proved to be instrumental for the assembly and spectral differences observed. Therefore, these presented properties of the platform described could likely produce much more complex, functional multi-chromophoric assemblies.

The thesis then closed with a brief overview and an outlook which discussed two multi-chromophoric assemblies, based on the work presented in Chapter 3–5.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QP Physiology
Library of Congress Subject Headings (LCSH):	Biomimetics, Renewable energy sources -- Research, Solar energy -- Research, Photovoltaic power generation, Porphyrins
Official Date:	September 2016
Dates:	Date Event September 2016 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	O'Reilly, Rachel K. ; Stavros, Vasilios ; Napier, R. (Richard)
Format of File:	pdf
Extent:	xvii, 161 leaves : illustrations, charts
Language:	eng

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