Multivalent Redox-Active Molecular Assemblies

Abstract

Although supramolecular strategies can be successful in mediating the assembly of π-surfaces, these assemblies rely solely on typically weak, non-covalent interactions. A macromolecular approach provides an opportunity for even greater control as covalent scaffolds can reinforce and/or direct the assembly of π-surfaces whilst also taking advantage of non-covalent interactions that drive self-assembly. Mediating π-assembly via macromolecular scaffolds can provide access to, i) robust materials owing to the macromolecular sizes, ii) molecules that have high fidelity, iii) materials that have hierarchical ordering (i.e., multiple levels of assembly) and iv) materials that have advanced functioning. The arrangement of functional aromatic units in three-dimensional (3D) space is relatively unexplored, whereas one-dimensional (1D) assembly of said units has been a target for supramolecular chemists over the last 30 years. This thesis will discuss these two macromolecular strategies towards guiding π-aromatic units: firstly, using a fullerene hexakis-adduct scaffold that pre-organises and positions the pendant aromatic units in 3D space, and secondly, using a polypeptide that capitalises on β-sheet forming peptide sequences and an artificial β-turn to organise embedded functional units into 1D assemblies. In both strategies, the macromolecular scaffolds facilitate a structure of order that organises photo- and/or redox-active units that can be investigated for their fundamental optoelectronic properties as well as potential applications such as in photovoltaics, photocatalysis and semiconductor devices. The macromolecular strategy in controlling π-assembly is still in its nascency, however, this thesis demonstrates the untapped potential bestowed upon multivalent, redox-active macromolecular materials.