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Title: Chiral metal organic materials and their application in enantioseparations of racemic chemicals : insights into the mechanisms involved
Author: Slater, Benjamin
ISNI:       0000 0004 9350 0089
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2020
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Metal organic materials are an emerging, increasingly studied group of materials for a wide range of potential applications. Synthesis of chiral variants of these materials can be readily synthesised by direct combination of metal nodes with chiral linking ligands. The resulting materials often have attractive enantioselective properties, where the framework can selectively adsorb one enantiomer from the racemic mixture. Understanding of the chiral separation process is an essential yet often overlooked area of research. Elucidation of the host-guest interactions between the framework and each enantiomer of a chiral guest, gives valuable mechanistic detail for the enantioselective process, but typically, this is rarely studied. Spectroscopic characterisation of the inclusion complexes elucidates the enantioelective interactions between the framework and each enantiomer of a chiral guest. This mechanistic information can be exploited to increase the preferential interactions of the separation process by substitution of framework features with other weaker or stronger interacting species. It was found that the terephthalate of ZnBLD has a particularly strong influence on the enantioselectivity, this is observed through the strong interactions with each enantiomer guests of 1-phenylethanol and limonene. Tuning of the framework for a particular separation process can then be achieved by synthesising closely related analogues. External influences such as time, temperature and solvent choice usually have a large influence on the enantioseparation ability of the framework. The choice of the solvent has a particularly strong effect on the separation process can in some cases can even reverse the enantioselectivity. Chiral MOFs typically require expensive enantiopure ligands, this thesis presents some alternative synthesis routes to lactate containing MOFs with substantially reduced reagent costs. The greenest and most economically friendly option developed utilises post-consumer polylactic acid to replace expensive L-lactic acid.
Supervisor: Ladewig, Bradley Sponsor: Commonwealth Scientific and Industrial Research Organisation ; Imperial College London
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral