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Title: Crystal engineering of porous steroidal organic crystals
Author: Bridgland, Lydia Naomi
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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Porous materials are highly valued for a wide variety of scientific and technological applications and organic molecular crystals offer an alternative to established inorganic materials. In this thesis, the porosity of tris-N-phenylureido steroidal crystals IS characterised and the versatility of the steroidal crystal system is demonstrated. Material properties can often be adjusted by mixing components in varying proportions to form alloys, but this phenomenon is rarely demonstrated for organic molecules. In organic crystals, molecules pack into an array which has symmetry and dimensions specific to the compound. Thus, in general, molecules cannot be substituted for molecules of a different compound. The studies presented here demonstrate that organic alloys are possible if the crystal structure possesses voids which are able to accommodate significant p0l1ions of the new molecules. A variety of multi-component steroidal crystals have been created with diverse and complex channel interiors. These have been characterised by optical microscopy, single X-ray crystallography, IH NMR and mass spectrometry. Finally, molecular machines which perform mechanical work on a molecular level are of great interest within the scientific community. The operational range of molecular motion is often too restricted to create macroscopic phenomena, but by confining the molecular machines to small spaces such as nanopores, molecular movement on the nanometre level can be sufficient to dominate the physical and chemical behaviour of guest molecules. In this thesis, the prospect of creating a new type of molecular machine assembly to propel molecules unidirectionally along crystal channels has been investigated. Crystal engineering has been used to design porous steroidal crystals with azobenzene moieties, capable of photoinduced isomerisation, protruding into the crystal channels. The resulting crystals have been analysed by optical microscopy and solid-state UV-vis spectroscopy, and the distribution of guest molecules within the crystals has been investigated by Raman and IR microspectroscopy and fluorescence microscopy.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available