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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthetic studies of N-heterocycles via catalytic reductive C-C bond formation and tertiary neopentyl substitution / Synthetic studies of N-heterocycles via catalytic reductive C-C bond coupling and tertiary neopentyl substitution

Grant, Christopher Donald 06 July 2012 (has links)
Whilst there are a large number of C-C bond forming reactions available for the construction of heterocycles a number of these protocols require the use of stoichiometric organometallic reagents. Since heterocycles are present in the vast majority of pharmaceutical agents the ability to forge these structures efficiently with a minimal amount of stoichiometric metallic waste is important. With this in mind we initiated a series of projects that focus on the use of [pi]-unsaturates to serve as surrogates to toxic, air and moisture sensitive nucleophilic organometallic reagents utilized in traditional C-C bond forming reactions. This has allowed us to develop catalytic couplings of vinyl azines to imines to form branched amines, to couplings of dimethylallene to isatin forming a tert-prenyl hydroxy oxindole and this neopentyl alcohol can be substituted with C-nucleophiles forming two contiguous quaternary all-carbon centers in our synthetic studies tert-prenyl indole alkaloid natural products. / text
2

Molecular tools for elucidating copper biochemistry: Water-soluble fluorescent probes and robust affinity standards

Morgan, M. Thomas 09 April 2013 (has links)
Copper is an essential trace element for living organisms and has both known and additional suspected roles in human health and disease. The current understanding of copper metabolism is substantial but incomplete, particularly in regard to storage and exchange at the subcellular level, although available evidence indicates exchangeable intracellular copper is in the monovalent oxidation state. Selective fluorescent probes with sufficient sensitivity to detect Cu(I) availability at physiologically relevant levels and at subcellular resolution would be valuable tools for studying copper metabolism. As a contribution toward this goal, this work describes the development of Cu(I)-selective fluorescent probes with greatly improved aqueous solubility, contrast ratio, and fluorescence quantum yield. This work also describes the development of water-soluble, 1:1-binding chelators that form colorless, air-stable copper(I)-complexes. By acting as copper(I) buffering agents and affinity standards, these compounds can serve a complementary role to fluorescent probes in the study of copper biochemistry.
3

Sulfonated polyphenylenes based on Armstrong’s acid as proton conducting membranes for fuel cell applications

Künzel-Tenner, Andy 12 September 2024 (has links)
Proton conducting membranes are a key component in fuel cell designs. Properties like proton conductivity, water uptake, ion exchange capacity and physiochemical stability dictate the performance and longevity of the complete fuel cell system. Designing a proton conductiting membrane takes several factors, such as monomer choice and their respective functionalization into account. Besides that, economically favourable reactions as well as environmental compability have to be considered. This work demonstrates the development of a fuel cell membrane material starting from broadly available, cost-efficient educts. Few reaction steps, also including cost-efficient reagents, have been employed in order to obtain a doubly sulfonated monomer based on naphthalene-1,5-disulfonic acid (Armstrong´s acid) suitable for polymerizations. Suzuki polycondensation of the given monomer partly yielded processable films for further investigation. A cost-efficient, atom-economic deprotection stategy was developed for sulfonated polyphenylenes, yielding proton conducting membranes. Further modification of the backbone structure, by incorporating an excess of hydrophobic meta,meta,meta-terphenylene units, led towards balanced properties of the material. The impact of polymer constitution, was investigated and discussed via the implementation of para,meta,para-substituted instead of meta,meta,meta-substituted terphenylene. Alternating and statistical copolymers including para,meta,para-substituted terphenylene were developed and investigated. The reported proton conducting membranes pose suitable and promising candidates for fuel cell applications.

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