UVM Theses and Dissertations
Format:
Print
Author:
McCarthy, Sean M.
Dept./Program:
Chemistry
Year:
2005
Degree:
PhD
Abstract:
A combinatorial mini-library of oxidatively robust, environmentally benign, peptide based, transition metal oxidation catalysts was synthesized and screened for oxidation of a variety of substrates. The catalysts exhibit high turnover numbers (TON) and turnover frequencies (TOF/h) for oxidation of primary and secondary alcohols to the corresponding carboxylic acids and ketones respectively. The catalysts employ novel oxidatively robust, peptide based ligands. The ligands were synthesized from inexpensive precursors utilizing oxazolone and benzoxazinone intermediates which allowed for the minimal use of protecting groups. Furthermore, the peptide ligand systems were prepared via solution phase methods, instead of solid phase techniques, allowing us to prepare multi gram quantities of each tripeptide. Catalyst preparation from the tripeptides is straightforward and inexpensive. Both amido-0 and amido-N forms of the catalysts were investigated for oxidation of primary and secondary alcohols by monitoring the reactions by ¹³C NMR spectroscopy for formation of products. We discovered that some of the catalysts are capable of forming oligomeric structures in concentrated solution,> 1 mM, and in the solid state as evidenced by preliminary variable temperature magnetic susceptibility data. The nature of the oligomers is not known at this point, but is currently under investigation.
An H-bonded cyclic dipeptide supramolecular library was also investigated synthetically and crystallographically for the purposes of understanding how molecular crystals assemble. We were able to successfully predict the structure of a cyclic dipeptide containing naphthalene units, cnap₂, based on patterns elucidated from the supramolecular library. Environmentally benign laboratory experiments suitable for use at the high school or college level were also developed. The first experiment we developed focuses on the investigation of colligative properties utilizing freezing point depression. The new lab substitutes benign fatty acids for commonly used aromatic and chlorinated aromatic hydrocarbons. The second laboratory we developed deals with the synthesis and characterization of biodiesel a more benign alternative for diesel fuel.
An H-bonded cyclic dipeptide supramolecular library was also investigated synthetically and crystallographically for the purposes of understanding how molecular crystals assemble. We were able to successfully predict the structure of a cyclic dipeptide containing naphthalene units, cnap₂, based on patterns elucidated from the supramolecular library. Environmentally benign laboratory experiments suitable for use at the high school or college level were also developed. The first experiment we developed focuses on the investigation of colligative properties utilizing freezing point depression. The new lab substitutes benign fatty acids for commonly used aromatic and chlorinated aromatic hydrocarbons. The second laboratory we developed deals with the synthesis and characterization of biodiesel a more benign alternative for diesel fuel.