The Supramolecular Chemistry of Amphiphilic Redox-Active Organic-Inorganic Hybrid Polyoxometalates

This thesis focuses on the synthesis and supramolecular assembly of Class II hybrid-POM amphiphiles, in which these molecules will be synthesized, characterized and their supramolecular assembly studied. Chapter 2 explores the development and supramolecular assembly of a hybrid-POM amphiphile {W17C20} based on a lacunary Wells-Dawson polyphosphotungstate cluster hybridised to two hydrophobic Cn (n = 10, 12, 14, 16, 18, 20) chains through phosphonic acid linkers. This investigation focused on how ligand chain length affects the supramolecular assembly and the redox activity of the supramolecular assembly. Here, the longer chain lengths led to smaller, stable more discrete assemblies which demonstrate contrasting redox chemistry to the molecular species. Chapter 3 studied the hierarchical self-assembly behavior of hybrid-POM amphiphile, where surface interactions and temperature stimuli were probed. Redox-active micelles based on {W17C20} were found to self-assemble into monolayers and retain redox-activity at glassy carbon electrode surfaces. Furthermore, based on the hydrophobicity of various carbon surfaces, micellar structures were found to transition upon deposition to other higher order structures such as fibers. Hierarchical selfassembly transition was also found when freezing aqueous micelle solutions of {W17Cn} which led to the formation of cylindrical micelles. The degree of order was correlated to the increasing chain length of the amphiphile. Furthermore, the cylindrical micelles could be isolated and acted as soft-templates for nanostructured metal oxide material. Chapter 4 focused on the development of new hybrid linkers and ligands based on the hybridisation of diphosphonate molecules (methylene diphosphonate (MDP), imidodiphosphonate (IDP) and pyrophosphate (PP)) with lacunary Wells-Dawson cluster {W17}. We found that based on the electronic nature of the diphosphonate, the POM cluster could be photoactivated with varying degrees upon hybridisation whi