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Spiropyran-based materials and MOF crystal imaging

Hancock, James 2020. Spiropyran-based materials and MOF crystal imaging. MPhil Thesis, Cardiff University.
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Abstract

This work is divided into two thematic sections. The first details the synthesis of two photo-active linkers and the attempted synthesis of MOFs containing the photoactive linkers to form functional materials. It also discusses the synthesis of the amorphous material AN64, as well as discussing the detailed characterisation of this material. The second section studies the size of NOTT-100 crystals after synthesis and after exchange with 12 different common lab solvents both before and after SEM imaging and studies the size distribution of particles in order to assess the environmental stability of these MOF crystallites. Part 1 A photoactive spiropyran core and two photo-active linkers were synthesised. In summary a series of combinatorial reactions were performed with the extended and non-extended photo-active linker in DMF, and a zirconium-based material was synthesised, but even when lower temperature combinatorial synthesis was performed no crystals large enough for single crystal X-ray diffraction formed. After altering both the modulator and temperature the solvent was changed. DEF was used instead of DMF in a series of combinatorial reactions with the non-extended linker, but a crystal of suitable quality did not form. Combinatorial synthesis was performed with aluminium, gallium and gadolinium and amorphous gallium and gadolinium-based materials were synthesised. Detailed characterisation of AN64 was performed. AN64 was found to be thermally and mechanical stable. The thermal stability of AN64 was studied and the resulting TGA mass loss graph appeared to show two overlapping decay curves which could indicate that two different solvent binding sites are present in AN64. A cycled TGA experiment showed AN64 was able to reversibly adsorb and desorb atmospheric water. 3 Part 2 Part 2 studies the size of NOTT-100 crystals after synthesis and after exchange with 12 different common lab solvents both before and after SEM imaging. We have developed a straightforward procedure for extracting particle size distribution from both optical and SEM images. In this study the SEM measurements were not innocent. The more polar and higher acceptor number solvents, even when only present in residual amounts after air drying, are enough to break up the crystallites when they are exposed to vacuum, however, there was no apparent correlation between solvent surface tension, vapour pressure and boiling point and the particle size distribution. There was no apparent trend between the secondary exchange solvent and the particle size distribution in the optical images of the crystals, prior to the SEM measurement.

Item Type: Thesis (MPhil)
Date Type: Completion
Status: Unpublished
Schools: Chemistry
Date of First Compliant Deposit: 24 November 2020
Last Modified: 24 Nov 2020 10:49
URI: http://orca.cardiff.ac.uk/id/eprint/136598

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