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acase@tulane.edu / 1 / Harrison Patrick Rahn

This dissertation will focus on NMR studies and photochemical experiments performed in a supramolecular host - guest assembly in aqueous media. Cavity of the synthetic resorcinarene based host molecule used in this study acts as a hydrophobic pocket for guests like dibenzyl ketones, N-alkyl-2-pyridone and tropolone ethers. Two molecules of the host self-assemble to form a capsular complex in the presence of a guest. It was possible to identify the binding modes of the guest molecules inside the cavity of the host using 1D and 2D NMR spectroscopy techniques like NOESY, TOCSY and DOSY. Photochemical reactivity of the bound guest molecules were found to be different from their reaction in isotropic solutions illustrating the ability of the host to confine the guests, the intermediate radicals and the photoproducts. Additionally, unlike many other supramolecular hosts, generally less significant substituent effects were found to play a major role in the binding motif and consequently, reactivity of the guest substrates. Dibenzyl ketones were used to probe the stability of the complex. By introducing different alkyl substituents in the para position and in the alpha-position, binding modes of the guests were altered. Their photochemical behavior correlated well with the structure established by NMR studies. Dynamic nature of the intermediate radicals bound to the guest was confirmed by formation of rearrangement products. Diastereoselective cyclization reactions of N-alkyl-2-pyridones, tropolone ethers and cyclohexadienone carboxamide appended to a chiral auxiliary were also studied. Observed selectivity in the reaction of methyl-substituted pyridones depended on position of the methyl substituent on the pyridyl ring.

Thesis (M.S.)--University of Florida, 2005. / Title from title page of source document. Document formatted into pages; contains 82 pages. Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 126-130). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 126-130). Also available on the Internet.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 4 uppsatser. Sammanfattning på svenska med titeln: Bispidinderivat : syntes och interaktioner med Lewis-syror.

Thesis (M.S.)--University of Florida, 2005. / Title from title page of source document. Document formatted into pages; contains 59 pages. Includes vita. Includes bibliographical references.

archives@tulane.edu / 1 / Hannah Aziz

<p> The use of Te-N-C heterocycles as supramolecular building blocks was investigated. The propensity of the heavy main-group elements to engage in secondary bonding interactions motivated a survey of the literature that identified the supramolecular association patterns that are most frequent in the crystal structures of tellurium compounds. A notation was proposed to classify those supramolecular synthons. The shortest Te-N secondary bonding distances are observed in the crystals of 1,2,5-chalcogenadiazoles which assemble the virtual four-membered ring [Te-Nb. Detailed computational investigations (OFT) established that the Te-N secondary bonding interactions are stabilized by a combination of electrostatic and Lewis acid-base covalent contributions. The study also indicated that the [Te-N] 2 supramolecular synthon meets the requirements of strength, directionality and reversibility that are necessary in supramolecular chemistry. A general method was developed for the synthesis of a wide variety of telluradiazoles. These compounds were used in experiments that probed the ability of steric effects to disrupt the self-assembly and select dimers instead of ribbon polymers. Derivatives resulting from the addition of Lewis acids and bases were also investigated. Photoelectron spectroscopy confirmed the details of the calculated electronic structures of benzo-2, 1,3-chalcogenadiazoles and mass spectrometry provided evidence of the association of these molecules in gas phase. A molecular mechanics method was parameterized to reproduce the structural features of the [Te-N]2 supramolecular synthon and, using this information, envision new supramolecular architectures based on 1,2,5-telluradiazoles. The use of the [Te-N]2 supramolecular synthon in the design and function of materials with properties such as thermochromism and nonlinear optical responses was demonstrated. Preliminary findings also highlighted the potential use of this approach in molecular materials that conduct electricity. </P> / Thesis / Doctor of Philosophy (PhD)