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Self-Assembly of Functional Helical Metallopolymers


Type

Thesis

Change log

Authors

Abstract

Self-assembled metal-organic materials have been championed as candidates for the next generation of functional materials. This has been attributed to their ‘bottom-up’ design and preparation, error-checking mechanisms, chemical tuneability, and novel functionality arising from the metal centres. This thesis proposes subcomponent self-assembled metallopolymers as a new and accessible class of material designed towards electronic and light-emitting applications. The metallopolymers are comprised of conjugated imine-based ligand strands that are helically wrapped around a linear array of closely spaced Cu atoms. To date, their development has been faced with several synthetic challenges. Moreover, the absence of methodologies to characterise and control the structures of these metallopolymers prevents their rational design towards performing a specific function. Remarkably, their charge-transport properties – perhaps the most interesting feature of these metallopolymers – have yet to be reported.

The work presented in this thesis seeks to explore methods to characterise and rationally tailor the structure of iminopyridine-based self-assembled metallopolymers and, for the first time, elucidate the charge-transport properties of this class of material. We have designed a novel bifunctional monomer unit which polymerises in the presence of CuI to afford long helical metallopolymers (>75 repeat units). We identify and develop techniques to control the length, regiochemistry and stereochemistry of the two helical strands and determine the effect that these three structural parameters have on the electronic properties of the metallopolymers. By controlling these structural properties, the polymerisation mechanism of this type of helical metallopolymer is elucidated, allowing the design of tailored metallopolymers. Electronic properties, including electrical conductivity, are investigated, noting anisotropic charge-transport through the metallopolymer and resistive switching behaviour. Finally, we employ the metallopolymer as a self-assembled scaffold, controlling the aggregation state of appended fluorophores, and thus modulating their photophysical properties. With several new design rules and behaviours for this class of metallopolymer in hand, we anticipate that the work presented in this thesis will fuel future studies towards creating the next-generation of metallopolymers for studying circularly polarised light emission and resistive switching applications.

Description

Date

2019-06-06

Advisors

Nitschke, Jonathan

Keywords

Metallopolymer, Self-Assembly, Molecular Wires, Electronic Materials, Fluorescent Materials, Polymers, Chirality, Helical Polymers, Light-Emission, Charge-Transport, Resistive Switching, Helical Scaffold

Qualification

Doctor of Philosophy (PhD)

Awarding Institution

University of Cambridge
Sponsorship
EPSRC