Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 113 for “"Metal-free"”.
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Metal-free C-H functionalisation methods
This thesis describes the development of two metal-free C–H functionalisation methods which encompass oxidations of sp³- and sp²-hybridised C–H bonds.Chapter 1 provides a brief introduction to the rapidly growing area of C–H functionalisation and outlines selected metal-catalysed and metal-free C–H …
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Metal-Free Photoredox-Mediated Ring Opening Metathesis Polymerization
Metal-free, photoredox-mediated ring-opening metathesis polymerization (MF-ROMP) is a novel approach to the synthesis of ROMP polymers. Whereas traditional, metal-mediated ROMP uses well-defined transition metal-alkylidene initiators in stoichiometric amounts, MF-ROMP uses a photo-oxidant to …
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DEVELOPMENT OF PRECIOUS METAL-FREE, LIGHT-ENABLED SYNTHETIC METHODOLOGIES
… majority of photocatalyzed reactions used organometallic complexes, whose properties made them very attractive. On the other hand, since the natural abundance of these metals is limited and their cost is constantly increasing, it would be highly desirable to replace them with cheaper and readily …
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Metal-free syn-dihydroxylation of alkenes using malonoyl peroxides
… of cyclopropyl malonoyl peroxide II in the metal-free syn-dihydroxylation of alkenes I. Chapter 1 outlines the available metal-free methods for achieving syn-1,2- dioxygenation of alkenes. The use of hypervalent iodine, selenium, sulfur and peroxide reagents are discussed in terms of the …
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Metal-containing and Metal-free systems for small molecule activation
… is to investigate small molecule activation with metal-containing and metal-free systems. Chapter 2 describes a tri-aryl benzene ligand scaffold for multimetallic N2 activation. A RuCp* complex was synthesized and characterized by NMR and X-ray crystallography. It offered an easy entry to …
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Molecular Dynamics Study of Characterization in Metal-Free Friction Materials
<p>Metallic friction materials currently used in industry may adversely impact the environment. Substitutions for metals in friction materials, on the other hand, can introduce operational safety issues and other unforeseeable issues such as thermal-mechanical instabilities and insufficient …
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Heavy-metal-free colloidal nanocrystal heterostructures – synthetic chemistry and growth mechanisms
… has been based on compositions with heavy metals (e.g., cadmium or lead) posing toxicity concerns to the consumers. Therefore, a better understanding of the synthetic chemistry and the growth mechanisms for heavy-metal-free nanocrystal heterostructures is critical before their …
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The effect of AC magnetic fields on liquid-metal free surfaces in industrialMHD
In this thesis we investigate free-surface instabilities which occur in various industrial processes involving liquid metal. Specifically, we examine a number of simple problems with a view to developing a plausible theoretical description based on MHD. Of particular interest is the behaviour of …
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METAL-FREE SELECTIVE SP3 C-H IMINATION AND COVALENT POSTSYNTHETIC MODIFICATION OF POLYSTYRENE BY DIRECT C-H AMINATION
… the properties of commodity polymers. Transition-metal-catalyzed C–H amination has emerged as a powerful tool for C–N bond formation, but these reactions typically rely on nitrogen protecting groups such as sulfonamides, which limits substrate scope and requires multiple steps. My work focused on …
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Characterization of Liquid Metal Free Surface Response to an Electromagnetic Impulse and Implications for Future Nuclear Fusion Devices
Liquid metals (LMs) are compelling candidates for use as plasma facing components (PFCs) in fusion devices to mitigate heat loading, limit damage due to erosion, and possibly breed tritium. When used as electrodes, such as in z-pinch devices, PFCs are subject to large current and magnetic flux …
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Metal-free methodology for the preparation of ynones using potassium alkynyltrifluoroborates and its application to the synthesis of natural products
A straightforward procedure for the preparation of ynones from potassium alkynyltrifluoroborate salts and acyl chlorides or anhydrides has been developed. The one-pot reaction is advantageous in that it does not require exclusion of air or water, is operationally simple, has broad substrate scope, …
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Myers-Inspired Selenium-Mediated Isomerization: An Efficient Generation of Contra-Thermodynamic Allenes and Alkenes with the Potential for Reductive Deamination of Primary Amines and Metal-Free Hydrogenation of Dienes
Novel methods of catalytic metal-free isomerization reactions are scarce. By combining precedents in reductive defunctionalization reactions, coupled with previous advances in selenium-catalyzed C-N bond forming reactions, we have developed a contemporary but efficient manner of reaching …
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Development of Novel, Regioselective Borylation Protocols
… has been geared heavily toward transition metal-catalyzed addition to double and triple bonds, though an increasing number of publications detail transition metal-free borylation techniques involving substrate-mediated activation of a diboron reagent. This dissertation describes the …
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Tailored diketopyrrolopyrrole-based organic dyes in photoelectrochemical cells for solar fuel synthesis
… most reports currently focus on precious metal-based light absorbers, thus limiting the wide-scale implementation of this technology. In this dissertation, the use of metal-free diketopyrrolopyrrole (DPP) chromophores has been explored as an alternative to precious metal-based dyes on …
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Greener Photoredox-Catalyzed Phosphonations of Aryl Halides
… environmental concerns. Milder, transition metal-catalyzed approaches have been developed, but can be limited by air sensitivity, cost, low reaction selectivity, and low functional group compatibility. Photoredox catalysis has been significantly advanced in the past decade in the pursuit of …
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The development of organic peroxide mediated oxidations
… thesis describes the development of two novel metal-free oxidations processes: a method to selective synthesis anti-diols directly from commercially available alkene starting materials and an organocatalytic sulfoxidation procedure using diketones as catalysts.;Chapter 1 describes a novel …
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Stability of thin-film PEDOT:PSS electrodes for neuromodulation
… screening of various electrode configurations. Metal-free PEDOT:PSS electrodes exhibited the best stability, with a failure rate of only 4.3% after 800 days. They significantly outperformed pristine and PEDOT:PSS-coated gold electrodes, which failed at rates of 89.7% and 82.1%, respectively. …
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Investigation of Fluorescence and Fluorescence Polarization as a Probe of Surface-Bound Species (Zinc Tetraphenylporphyrin, Ruthenium Tris(bipyridine))
… to study species deposited on surfaces. Metal-free and zinc tetraphenylporphyrin and ruthenium tris(bipyridine) were deposited onto glass, single crystal silicon and electrodes of indium oxide coated glass, pyrolytic graphite and thin gold films. Deposition was accomplished by (a) drying …
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