New anion receptors for molecular recognition and organocatalysis

This thesis describes the investigation of anion binding molecules in application to molecular recognition and organocatalysis. A focus is made on exploring the properties of σ-hole interactions: halogen and chalcogen bonding which are scarcely studied in the context of anion sensing, especially in an aqueous environment. Chapter 2 describes the preliminary design of a tetradentate XB anion receptor. This system is shown to be effective for anion complexation in organic solvent media, more so than the isostructural HB analogues. Fluorescent sensing and chiral discrimination capabilities are also demonstrated. Chapter 3 discusses the water-soluble, preorganised XB and ChB anion receptors. This provides the first examples of charge-neutral, all-XB and all-ChB host molecules to be used for anion binding in water. In addition to the fundamental studies of anion coordination, applications in fluorescent and electrochemical anion sensing are shown. Chapter 4 details the development of biomimetic transesterification catalysts that include an oxyanion hole function. The series of compounds is iterated towards high reactivity, arriving at highly effective catalysts with a modular, easily customised structure.