Supramolecular Functional Materials Based on Cucurbit[8]uril-Enhanced π–π Interactions
On account of the dynamic and controllable nature, host-guest chemistry has been applied in research areas including drug delivery, sensing, catalysis, and nanotechnology. In particular, the cucurbit[n]uril (CB[n]) family of macrocyclic hosts has attracted considerable attention over the last decade. Advantages of CB[n]-based systems include compatibility with a wide guest scope of molecules, a high binding affinity that spans a wide range (10³ – 10¹⁵ M⁻¹), proven biocompatibility and stability in physiological conditions. In this thesis, for the first time, a new CB[8] binding mode is introduced as “CB-enhanced π–π interactions” in Chapter 2. Later, in Chapter 3, these interactions are further explored in the context of oligopeptide assemblies to form controlled heteropeptide dimers which are applied towards on-resin recognition of peptides and proteins with excellent recyclability and selectivity. The uptake and stabilisation of insulin prove a new route to room-temperature storage and utilisation of insulin. Then, in Chapter 4, cyclic peptide structures designed to form tight assemblies are investigated. Using CB[8]-enhanced π–π interactions, the assembly behaviours of CB-cyclic peptide complexes are studied within a constrained environment. The new host-enhanced π–π interactions are further exploited in the fabrication of supramolecular polymer networks in Chapter 5. Through careful selection of the second π-rich guest, the association and dissociation of the network are controlled to realise slow dissociation dynamics which result in glass-like properties being accessed for the first time in supramolecular polymeric materials. Last but not least, Chapter 6, a perspective of this thesis, demonstrates the development and utility of CB-enhanced π–π interactions within supramolecular and biological systems.
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