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Title: New ultimetallic assemblies as photoluminescent materials
Author: Duerrbeck, Andre
ISNI:       0000 0004 7656 8647
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2016
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During the last few decades significant progress has been made in the area of supramolecular polymers, where monomers are held together by non-covalent interactions. In particular, the formation of macromolecular assemblies by employing a metal-ion induced self-assembly process in solution is of significant interest. These supramolecular metallo-polymers combine common features of traditional covalently-bound polymers with the unique characteristics introduced by metal ions. So far, the research in this area has mainly focused on the metal-induced self-assembly of d-block metals and ditopic tridentate organic ligands. The overall aim of this project was to extend the knowledge in this area to Ln(III)-containing soluble supramolecular metallo-polymers and to study their overall photophysical properties. The introduction chapter gives an overview of the basic principles of lanthanide photophysics as well as brief explanations of the methods used in this thesis. Furthermore, some literature examples of soluble coordination polymers are presented. Chapter two describes the synthesis of new substituted pybox ligands and their complexation to various Ln(III) metal ions. The aim of the chapter was to establish a trend between the ligand triplet state energies and the quantum yield of the Eu(III) and Tb(III) complexes. Chapter three focusses on the preparation of coordination polymers by a self-assembly process in solution between Ln(III) metal ions and ditopic pybox ligands. One ligand was found to result in high Eu(III) emission yields of up to 73% as well as a unique dynamic behaviour in solution. Other ligands prepared showed a quenching mechanism such as energy-back transfer to the ligand triplet state which was further investigated by transient absorption spectroscopy. In chapter four the solution phase self-assembly between Eu(III) and a rigid ditopic tridentate terpyridine ligand which results in the formation of supramolecular metallo-networks in the solid state is described. Depending on the ligand to metal ratio used, the morphology of these materials can be altered from one-dimensional micron-sized fibres to a three-dimensional coordination network. The terpyridine-based ditopic ligand can act as an efficient sensitizer for Eu(III) emission whereby the emission lifetimes and ligand triplet state energies of the metallo-polymers strongly depend on the ligand to metal ratio. The obtained micron-sized fibres can act as an efficient optical wave-guide for Eu(III) emission.
Supervisor: Long, Nicholas Sponsor: Imperial College International Office
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral