Carbohydrate recognition in water still remains one of the most challenging tasks for supramolecular chemists. Despite the challenges, the Davis group has had good success in designing and synthesising compounds capable of carbohydrate recognition. Within this body of work 6 novel carbohydrate receptors are reported, based upon the anthracene design shown below. The majority of the reported receptors displayed good to excellent affinities to all-equatorial carbohydrates. One of the synthesised receptors, containing methoxy functionality on the anthracene units, demonstrated remarkably high affinity to maltodextrins, such as maltotriose and maltotetraose (Chapter 2). The binding affinities displayed towards maltodextrins by this receptor, ~2000 M-1, are amongst the highest affinities reported for synthetic carbohydrate receptors in water, and they also are of a similar magnitude to the binding affinities displayed by natural carbohydrate receptors, lectins. A selection of unsymmetrical receptors were also synthesised, wherein one anthracene moeity was unsubstituted and the other was substituted with either bromines, methylesters or carboxylic acids (Chapter 3). These designs were implemented in order to red-shift the receptor's fluorescence emission wavelength, something they did achieve, however only at the consequence of a reduced increase in the receptor's fluorescence intensity upon carbohydrate binding. Of the unsymmetrical receptors synthesised, one, containing a tetracarboxylic acid substituted anthracene, displayed exceptional binding to all-equatorial carbohydrates, binding D-glucose with a binding affinity of 186 M-1. This represents the highest binding affinity to glucose reported. Additionally, the receptor displayed a selectivity of 186:1 for glucose over mannose, a selectivity higher than many lectins. One receptor, wherein one anthracene unit was substituted with a naphthalene, displayed no affinity towards carbohydrates in water (Chapter 4). Such a result, highlighted the importance of hydrophobic interactions are in achieving carbohydrate recognition in water. Finally, further investigations into the reported binding of carbohydrates by a porphyrin based system were carried out (Chapter 6). The results showed tight 1:1 binding between the carbohydrate and the porphyrin was absent, and instead kinetically slow readjustments of porphyrin aggregates appeared to be responsible for the change in UV-vis and fluorescence properties of the porphyrin.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:686165 |
| Date | January 2015 |
| Creators | Renney, Charles M. |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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