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Title: Reversible directed phase transfer of M4IIL4 and M4IIL6 cages
Author: Georges, Maureen Claire Alma
ISNI:       0000 0004 6424 1831
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2017
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A major function assessed by Nature is the transport of a cargo between two different media, such as anions through cell membranes. Mimicking this function using complex systems is one of the biggest challenge of supramolecular chemistry. Metallo-organic cages are an important breakthrough in the encapsulation and transport of small molecules, providing a crucial platform for the development of systems chemistry. Binding a network member within a tetrahedral cage allows it to be hidden and then revealed upon receipt of a release signal, or transported as a cargo between spatially distant parts of a network. Larger capsules may also isolate subsystems from each other in the manner of vesicles. These dynamic architectures are synthesised by self-assembly, which involves the simultaneous formation of multiple coordinative and dynamic covalent linkages during the same overall synthetic process. Their shape and binding properties can be tuned by changing the subcomponents such as metals or ligands. Great progress has been reported in recent years in the development of three-dimensional cages that can interact with specific guest species, but there are limitations associated with the transport of these systems. Recent work by Nitschke et al. have successfully addressed practical separations problems by transporting a tetrahedral cage and its cargo from water into an ionic liquid layer. However, this system is not ideal as the process is triggered by an anion exchange not by a direct stimulus. This thesis reports the synthesis of an ionic liquid inspired tetrahedral system achieving reversible transport between water and an immiscible organic solvent driven by a change in temperature. Once the switchable capsules were obtained and characterised, their ability to move between different solvent phases upon heating was investigated. A capsule-mediated transport system as developed that is both directional and reversible. The flow of the capsule and its encapsulated cargo is directed using stimuli such as temperature modification. Ultimately an apparatus that allows the switchable capsules to move along a channel has been developed.
Supervisor: Nitschke, Jonathan Russell Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: coordination cages ; supramolecular ; reversible phase transfer ; temperature variations