| dc.description | The first study in this thesis, Chapter Three, involves the use of DFT to investigate the hydrogen halide dimers, (HF)2, (HCl)2 and (HBr)2. Emphasis is focused upon an assessment of the performance of the hybrid DFT methods in predicting the geometry, binding energy and vibrational properties of these dimers. Overall, the hybrid density functional methods adequately predict the properties of the halide dimers and the BHandHLYP and B1LYP density functional methods offer a competitive alternative to the popular B3LYP method. In Chapter Four, the ability of hydrogen bonds to act as catalysts is examined. In the study of the aminolysis of 6-chloropyrimidine, derivatives of uracil stabilize the transition structures by the formation of multiple hydrogen bonds, thus catalyzing the aminolysis reaction. This study highlights the catalytic potential of hydrogen bonding and the importance of a well-chosen hydrogen bond acceptor. In the following chapter, Chapter Five, the direct aldol reaction as catalyzed by proline is investigated to assess the feasibility of the proposed reaction mechanism and the potential role of the solvent. This study is a simple example illustrating the potential of small molecules, such as proline, to act as catalysts in biochemical reactions. Chapter Six examines the structural and energetic effect the introduction of electron-withdrawing substitutents on Cgamma has on the cis-trans isomerization in N-acetylproline methylamide. This study illustrates the important role the intramolecular N-H &cdots; N hydrogen bond plays in the cis-trans isomerization and the catalytic potential of hydrogen bonds. | en_US |
