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Exploring new routes towards photoactive assemblies

Thomas, Cerys. 2006. Exploring new routes towards photoactive assemblies. PhD Thesis, Cardiff University.

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Abstract

With increased interest in charge separated states formed in Photosystem II, we set out to synthesise a series of novel photoactive assemblies whereby the components comprising the arrays are linked by a variety of methods. We also considered the capabilities of the electron donors and acceptors separately with focus on porphyrins and quinones respectively. Along this theme, we prepared a number of novel amine derivatives of 2,3-dichloro-l,4-naphthoquinone and studied their electrochemistry. Thiol and mixed thiol/amine derivatives of 2,3-Khchloro-l,4-naphthoquinone were also synthesised and studied electrochemically. Synthesis of a bis-porphyrin-terpyridine molecular array was attempted using three methods. The method showing greatest promise is direct coupling of the porphyrins with the terpyridine. Comparison of the luminescence of Meso-5,10,150-tetrakis(4-iodophenyl)porphyrin with its bromo, chloro and hydrogen analogues was carried out in addition to their zinc complexes. As expected, iodine is the strongest quencher, followed by bromine, chlorine and hydrogen. Altering the substituents of the porphyrin has less of an effect on the luminescence when the porphyrin is metallated with zinc(II) than in the free base. A new route to synthesise 4-iodobenzaldehyde is reported starting with 4-iodotoluene. Two novel A4-substituted porphyrins were prepared utilising the Heck reaction. Using the Mannich reaction, we synthesised two novel tetraza macrocycles functionalised with phenol pendant arms and their lanthanide and transition metal complexes. Synthesis of cyclen bearing specific phenol and naphthol groups at all four positions was found to be hindered, possibly by the stability of the cyclen intermediate in addition to the lack of reactivity of these phenol and naphthol groups. Preparation of a novel cyclen-tetraporphyrin array was found to be forbidden for the same reasons. Following the synthesis of 5-iodovanillin, the preparation of the corresponding symmetrical porphyrin was reported which is a candidate for further work in this area.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Chemistry
Subjects: Q Science > QD Chemistry
ISBN: 9781303182594
Date of First Compliant Deposit: 30 March 2016
Last Modified: 12 Feb 2016 23:14
URI: http://orca.cardiff.ac.uk/id/eprint/55727

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