Molecular balances for measuring non-covalent interactions in solution
View/ Open
word thesis.zip (51.28Mb)
Adam2015.pdf (13.14Mb)
Date
30/06/2015Item status
Restricted AccessEmbargo end date
31/12/2100Author
Adam, Catherine
Metadata
Abstract
Non-covalent interactions in solution are subject to modulation by surrounding solvent
molecules. This thesis presents two experimental molecular balances that have been
used to quantify solvent effects on non-covalent interactions, including electrostatic
and dispersion interactions.
The first chapter introduces literature where non-covalent interactions have been
studied in a range of solvents, particularly those where the effects of aqueous or
fluorous solvents have been investigated. These solvents are of particular interest as
they both invoke solvophobic effects on organic molecules, but have differing
chemical and physical properties.
The second chapter describes the adaptation of the Wilcox molecular torsion balance
to study interactions between organic and fluorinated carbon chains in a range of
solvents. Solvent cohesion was found to be the principle force driving both the alkyl
and fluorous chains together in aqueous solvents, where no contribution to the
interaction energy arising from dispersion forces could be detected. In fluorous and
polar organic solvents evidence was found for weak favourable dispersion interactions
between the alkyl chains. In contrast dispersion forces between the chains were found
to be disrupted by competitive van der Waals interactions with surrounding solvent
molecules in apolar organic solvents. Association of the fluorous chains was found to
be solely driven by solvent cohesion.
The final chapter describes the design and synthesis of a novel synthetic molecular-balance
framework and describes its application to simultaneously measure solvent
and substituent effects on the position of conformational equilibria. Despite the
simplicity of the model system, surprisingly complicated behaviour emerged from the
interplay of conformational, intramolecular and solvent effects. Nonetheless, a large
data set of experimental equilibrium constants was analysed using a simple solvent
model, which was able to account for both the intuitive and more unusual patterns
observed. A means of dissecting electrostatic and solvent effects to reveal pseudo gas-phase
behaviour has resulted from the analysis of experimental data obtained in many
solvents.