This dissertation examines the concept that well defined hosts can be effectively used for controlling product distribution in photochemical reactions. Spatially confined cavities provided by zeolites and water-soluble synthetic organic hosts such as octa acid and dendrimers are explored as reaction media Chapter one provides an introduction to water soluble well defined supramolecular hosts and reasoning for why they were considered. Several highlights in supramolecular fields on water soluble host-guest systems from photochemical perspective are addressed Chapter two concentrates on efforts to control excited state chemistry and physics of organic molecules through the use of hydrophobic cavity provided by an octa acid host. Aromatic guest molecules of various sizes have been included in the host and their photophysical behavior was studied. Octa acid host was shown to be an effective medium for conducting photochemical reactions in water Chapter three presents photochemical reactions carried out in hydrophobic cavities provided by phenolic dendrimers. Host's hydrophobicity is probed through fluorescence of pyrene. Organized media could control the product distributions by influencing the reaction at any or all stages. Examples of these are discussed in this chapter Chapter four presents introduction to asymmetric photoreactions in various media. General introduction about structure and properties of zeolites are addressed Chapter five discusses the asymmetric induction during photocyclisation of tropolone ethers within faujasite Y zeolites. Tropolone ethers undergo a 4-pi electrocyclization resulting in chiral products. Enantio and diastereo selectivity of the products was examined with chiral inductor and chiral auxiliary approach respectively. Density functional calculations have been used to understand the reasons for the high chiral induction observed experimentally and the role of cations in influencing the stereochemical outcome of the reaction Chapter six discusses the diastereoselectivity in the photorearrangement of 3,3-dimethyl-4-oxo-3,4-dihydro-naphthalene-1-carboxylic acid and 3,3,5-trimethyl-4-oxo-cyclohexa-1,5-dienecarboxylic acid derivatives within zeolites. A cation dependent diastereomeric switch was observed with 3,3,5-trimethyl-4-oxo-cyclohexa-1,5-dienecarboxylic acid derivatives Chapter seven concentrates on understanding alkali metal ion-organic molecule interaction through computations. Computational studies were performed to support the experimental results on regio/stereoselective photoreactions within zeolites. Theoretical methods such as HF, B3LYP in Titan and Gaussian 98 suite of programs were used in this regard / acase@tulane.edu
| Identifer | oai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_25458 |
| Date | January 2004 |
| Contributors | Kaanumalle, Lakshmi Sireesha (Author), Ramamurthy, V (Thesis advisor) |
| Publisher | Tulane University |
| Source Sets | Tulane University |
| Language | English |
| Detected Language | English |
| Rights | Access requires a license to the Dissertations and Theses (ProQuest) database., Copyright is in accordance with U.S. Copyright law |
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