Synthesis and characterisation of small molecule and macromolecular photoredox catalysts for radical thiol-ene reactions
type: CreativeWork
description: The use of polynuclear complexes is attracting significant attention, offering several advantages over mononuclear analogues. In the context of this project, the presence of several photoactive centres can lead to a multi-electron transfer in a single step and offering other modalities. With the aim to improve the reactivity and stability of photoredox catalysts, multinuclear photoredox catalysts were developed. Consequently, bipyridyl monomeric and trimeric ligands functionalised with imine and amine functionalities were synthesised via Schiff base condensation and reductive amination reactions, respectively. The ligands were then reacted with cis-dichlorobis (2,2'-bipyridine) ruthenium (II) to afford two new mononuclear and two new trinuclear Ru(II)-based complexes. The resulting complexes were then fully characterised by various spectroscopic and analytical techniques such as 1H NMR, 13C{1H} NMR, FT-IR spectroscopy and mass spectrometry. Furthermore, electrochemical, electronic absorption and emission studies for the complexes were conducted and the collected data displayed the effects of ligand modifications on the photophysical and redox properties of the complexes. All the ligand-modified complexes exhibited red shifted emission spectra (614−633 nm) relative to the [Ru(bpy)3](PF6)2 complex (609 nm) and this emission band was attributed to the transition from the triplet MLCT excited state (3MLCT) to the ground state. The excited state redox potentials for the ligand-modified complexes were comparable to that of the known complex thus displaying promising photocatalytic activity. The photoexcited [Ru(bpy)3] 2+ complex had the most positive excited state reduction potential (Ered (2+*/+) = +0.350 V vs Ag/Ag+), making it a more powerful oxidant than the photoexcited states of the ligand-modified complexes. The complexes were then evaluated as photoredox catalysts in the radical hydrothiolation reaction of olefins (thiol-ene reactions) to produce thioethers, which…
abstract: The use of polynuclear complexes is attracting significant attention, offering several advantages over mononuclear analogues. In the context of this project, the presence of several photoactive centres can lead to a multi-electron transfer in a single step and offering other modalities. With the aim to improve the reactivity and stability of photoredox catalysts, multinuclear photoredox catalysts were developed. Consequently, bipyridyl monomeric and trimeric ligands functionalised with imine and amine functionalities were synthesised via Schiff base condensation and reductive amination reactions, respectively. The ligands were then reacted with cis-dichlorobis (2,2'-bipyridine) ruthenium (II) to afford two new mononuclear and two new trinuclear Ru(II)-based complexes. The resulting complexes were then fully characterised by various spectroscopic and analytical techniques such as 1H NMR, 13C{1H} NMR, FT-IR spectroscopy and mass spectrometry. Furthermore, electrochemical, electronic absorption and emission studies for the complexes were conducted and the collected data displayed the effects of ligand modifications on the photophysical and redox properties of the complexes. All the ligand-modified complexes exhibited red shifted emission spectra (614−633 nm) relative to the [Ru(bpy)3](PF6)2 complex (609 nm) and this emission band was attributed to the transition from the triplet MLCT excited state (3MLCT) to the ground state. The excited state redox potentials for the ligand-modified complexes were comparable to that of the known complex thus displaying promising photocatalytic activity. The photoexcited [Ru(bpy)3] 2+ complex had the most positive excited state reduction potential (Ered (2+*/+) = +0.350 V vs Ag/Ag+), making it a more powerful oxidant than the photoexcited states of the ligand-modified complexes. The complexes were then evaluated as photoredox catalysts in the radical hydrothiolation reaction of olefins (thiol-ene reactions) to produce thioethers, which…
author: Motimani, Nozuko
keywords: Chemistry
date published: 2021
date modified: 2026-07-22T22:23:24Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Chemistry

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property ID: Handle
value: http://hdl.handle.net/11427/35921