Sigma-hole non-covalent interactions in anion host-guest chemistry and the mechanical bond

Thesis

This thesis describes the use of σ-hole interactions in acyclic, macrocyclic and mechanically interlocked receptors for anion recognition and sensing.

Chapter 1 provides an overview of the field of supramolecular host-guest chemistry with particular focus on host systems bearing σ-hole donor motifs for anion guest binding, followed by a discussion of mechanically interlocked host molecules for anion recognition and sensing.

Chapter 2 describes the synthesis of air and water stable acyclic tellurium and selenium-based chalcogen bonding receptors followed by an investigation of their thermodynamic anion binding properties in organic and mixed aqueous/organic solvent media. The integration of halogen bonding and chalcogen bonding motifs into mechanical interlocked molecular structural frameworks is also explored.

Chapter 3 details combining σ-hole donors and the BINOL motif to form chiral host receptors. The synthesis of a chiral halogen bonding [2]rotaxane structure is described as well as chiral acyclic and macrocyclic receptors possessing four integrated halogen bond-donors which are shown to be capable of binding chiral carboxylate anions. The enantioselective properties of these receptors were determined by monitoring the fluorescence changes of the respective receptor’s integrated BINOL or pyrene fluorophore upon chiral anion guest binding.

Chapter 4 introduces the use of halonium cation species in supramolecular chemistry. Primarily, this chapter investigates the stability of iodonium species in pyridyl-based pseudorotaxane assemblies and mechanically bonded [2]rotaxanes using NMR spectroscopy.

Chapter 5 summarises the conclusions of this thesis.

Chapter 6 describes the experimental procedures carried out in this work detailing characterisation of novel compounds presented in chapters 2-4. Additional information pertaining to crystallographic data and computational work are provided in the Appendices.

Authors: Liew, JY

• DOI: 10.5287/ora-goge7gkgp
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Mechanically Interlocked Molecules; Host-Guest Chemistry; Macrocycles; Supramolecular Chemistry; Intermolecular Interactions; Rotaxanes and Catenanes; Chalcogen Bonding; Halogen Bonding
• Subjects: Chemistry