- Title
- Assessment of the host properties of selected optically pure, racemic and achiral compounds
- Creator
- Jooste, Daniel Victor
- Subject
- Organic compounds -- Synthesis Cyclic compounds
- Date Issued
- 2017
- Date
- 2017
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10948/18826
- Identifier
- vital:28735
- Description
- This study focussed on the synthesis and host properties of four different broad categories of potential host compounds, namely optically active and racemic TADDOL [(4R,5R)-α,α,α’,α’-tetraphenyl-1,3-dioxolane-4,5-dimethanol] and derivatives, TTFOL [(3R,4R)-2,2,5,5-tetraphenyltetrahydrofuran-3,4-diol], amino acid ester-derived compounds [(S)-4-(2-amino-3-hydroxy-3,3-diphenylpropyl)phenol], and compounds derived from xanthone [9-amino-9-phenylxanthene and 1,2-bis(9-phenyl-9H-xanthen-9-yl)hydrazine]. The potential hosts were recrystallized from a range of possible guest species and the resulting solids analysed by 1H-NMR spectroscopy. If inclusion was observed by this technique, the complexes were analysed further using single crystal X-ray techniques and thermal experiments where possible. Competition studies were carried out where these were deemed appropriate. Optically active and racemic TADDOLs were synthesized using L-(+) and DL-(±)-tartaric acid respectively. Two further derivatives were prepared whereby the hydroxyl groups were substituted for chlorine and azide in order to assess the effect of this change on the inclusion ability. Both the optically active and racemic TADDOLs displayed similar host abilities, complexing with guests with 1:1 host:guest ratios as determined through 1H-NMR spectroscopy. Competition experiments showed that both forms of TADDOL exhibited similar guest preferences for pyridine and the methylpyridine isomers. Pyridine however was preferred over 2-methylpyridine by optically active TADDOL while the racemic form preferred this methyl-substituted guest over pyridine. Thermal analysis studies showed, surprisingly, that the TADDOL complexes containing pyridine had higher relative thermal stabilities than those containing the methylpyridines, whether the host was optically active or not. The preference order of these hosts for these guests can, therefore, not be used as a predictor for the relative thermal stability of the complexes. TTFOL was found to include only ethanol, 2-methylpyridine and dioxane from the range of guest species used; the complex with dioxane did not produce X-ray quality crystals. The L-tyrosine derivative, (S)-4-(2-amino-3-hydroxy-3,3-diphenylpropyl)phenol, was an ineffective host incapable of including any of the guests used in these experiments. The two xanthone derivatives, 9-amino-9-phenylxanthene and 1,2-bis(9-phenyl-9H-xanthen-9-yl)hydrazine each formed complexes with one guest species (morpholine and DMF, respectively).
- Format
- ix, 144 leaves
- Format
- Publisher
- Nelson Mandela Metropolitan University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela Metropolitan University
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NMU School of BioMolecular and Chemical Sciences
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