Engineering biofunctional 1,10-phenanthroline ligands for low-spin d6 luminophores: towards targeted bioimaging

Ibbott, Alexandra 2025. Engineering biofunctional 1,10-phenanthroline ligands for low-spin d6 luminophores: towards targeted bioimaging. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

This thesis presents the design, synthesis and characterisation of functionalised 1,10- phenanthroline derivatives as ligands for phosphorescent Re(I), Ru(II) and Ir(III) complexes, with detailed discussions into their photophysical properties and potential towards targeted organelle imaging, biomolecular tracking and sensing applications. Chapter 2 investigates a straightforward two-step synthetic approach towards a diverse range of amine-substituted 1,10-phenanthroline ligands. The photophysical properties of their corresponding Ru(II) complexes were compared to the archetypal [Ru(bpy)3] 2+ . Chapter 3 extends this platform by incorporating a cholesterol moiety into the ligand framework, producing Re(I), Ru(II) and Ir(III) complexes designed as cholesterol-tagged phosphorescent probes. Preliminary cellular studies were conducted to assess probe endocytosis, cytotoxicity and performance, with comparisons drawn to literature examples of established commercial imaging agents. Chapter 4 explores the synthesis and characterisation of potential mitochondrial-targeting imaging probes. Achieved through the formation of triphenylphosphonium-functionalised 1,10- phenanthroline derivatives and their corresponding Ru(II) and Ir(III) phosphorescent complexes. Comparative analyses of the redox and photophysical properties of these complexes revealed how the lipophilic cations modulate photoluminescence, relative to their non-cationic analogues. A triethylammonium-functionalised ligand was also synthesised, with its complexes offering further insight into the observed photophysical variations. Chapter 5 studies the redox activation and subsequent phosphorescent and colourimetric “off/on” switch of a bis(5-amino-1,10-phenanthroline)-2-aza-anthraquinone bridged Ir(III) dimer. The investigation focused on how the redox sensitivity of the 2-aza-anthraquinone moiety served as the driving force for these observations, with potential applications in thin-film sensing or hypoxic imaging.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Chemistry
Date of First Compliant Deposit:	4 November 2025
Last Modified:	05 Nov 2025 10:21
URI:	https://orca.cardiff.ac.uk/id/eprint/182106

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