A water-soluble phosphate-footed cavitand : synthesis and binding properties with small neutral organic molecules
This thesis presents a study of apolar host-guest complexations between a bowl-shaped cavitand host and small neutral organic guest molecules in aqueous solutions. The watersoluble host molecule-cavitand 1, with methyl groups on the rim positions and hydrophilic phosphate groups at the pendent po...
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| Language: | English |
| Published: |
2009
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| Online Access: | http://hdl.handle.net/2429/10642 |
| Summary: | This thesis presents a study of apolar host-guest complexations between a bowl-shaped
cavitand host and small neutral organic guest molecules in aqueous solutions. The watersoluble
host molecule-cavitand 1, with methyl groups on the rim positions and hydrophilic
phosphate groups at the pendent positions, was synthesized. It forms 1:1 host-guest complexes
in aqueous solutions exclusively with most investigated guest molecules. Binding constants of
these complexes were determined from ¹H NMR titration experiments. The strongest bindings
were found between host 1 and small ester guest molecules. Variable temperature NMR
titration experiment uncovered that binding processes were driven by favorable enthalpy
changes accompanied with unfavorable entropy changes. These results were discussed in
terms of the attractive van der Waals interactions between host and guest as well as the
hydrophobic effect. The geometry of the complexes in aqueous solution was elucidated by ¹H
NMR spectroscopy and molecular mechanics calculations. For guests containing two potential
binding sites, they form isomeric complexes with host 1. |
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