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 174 for “"electron-withdrawing"”.
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Synthesis, Properties, and Reactivity of Pentafluorophenyl Substituted Cyclopentadienes and Their Transition Metal Complexes
… well-chosen ligand substituents. Studies of electronic substituent effects ideally employ a wide range of electron-donating and electron-withdrawing groups. Unfortunately, most of the available electron-withdrawing groups suffer from problems with Cp ligand synthesis, Cp anion stability, and …
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Modifying electronic and solid-state properties of fullerenes, polycyclic aromatic hydrocarbons, and perylene diimides
… energy sources and low energy consumption electronics devices. Organic photovoltaics, transistors, and light-emitting diodes are actively being developed as replacements for traditional energy sources and electronic devices. Strong electron acceptors are required to increase the efficiency …
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A New Terazulenic Platform
… interest in designing smaller and more efficient electronic devices, and many scientists have been pursuing the design of materials for applications in molecular electronics. One of the special interests is the design of molecular rectifiers. This thesis includes the work toward a novel rectifying …
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Selective Borylations of Carbon-Carbon pi-Bonds
… use of a diboron reagent to install boron on the electron withdrawing allenoate scaffold as well as on disubstituted 1,3-diynes. Lastly, this dissertation will cover the preliminary anti-fungal activity of a novel oxaborole scaffold. We investigated the borylation of the electron withdrawing …
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Synthesis and investigation of quinoline based ß-haematin formation inhibitors as potential antimalarials
… group in the 4-aminoquinoline moiety with an electron withdrawing and hydrophilic substituent results in retention of antiplasmodial activity in the 4-aminoquinoline class of compounds was investigated...
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Electrochemiluminescence of Various Systems
The effects of electron withdrawing and electron donating groups on the electrochemiluminescent (ECL) properties of tris(2,2'-bipyridy) ruthemium(II) (Ru(bpy)₃²⁺ where bpy = 2,2'-pyridine) is reported. The electrochemistry of Ir(ppy)₃ (ppy = 2-phenylpyridine) and Os(phen)₂(dppene)²⁺ (phen = …
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Molecular electrocatalysis of hydrogen evolution: catalytic design studied by density functional theory
… of the substituents R, which range from strongly electron-donating to strongly electron-withdrawing. Because two of the reduction potential lines intersect at a Hammett constant consistent with a slightly electron-donating substituent, we predicted that the Co(II/I) couple and Co(III/II)-hydride …
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Borylations and Silylations of Alkenyl and Alkynyl Carbonyl Compounds Employing a Mild and Environmentally Friendly Cu(II) Catalyst
… system is disclosed. Using this catalyst system, electron deficient alkenes and alkynes with diverse functional groups are borylated and silylated in high yields and with short reaction times. In the case of electron deficient alkynes the identity of the electron withdrawing group controlled …
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Synthesis and characterization of heterocyclic polymers: polybenzoxazoles and cyanate ester networks
… constant of insulators, appropriate for microelectronic applications. The second portion of the thesis focused on cyanate ester or polycyanurate networks generated from dicyanate monomers. The influence of electron withdrawing and donating groups on the behavior of the network forming curing …
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Pushing the Limits of the Lithium Indicator Carbon Acidity Scale Using Cyclopentadiene Chemistry and 19F NMR Spectrometry
… perfluoro-4-tolyl, and perfluoro-4-pyridyl, electronegative groups listed in order of increasing electron-withdrawing power. The most acidic compound in the set was 1-pentafluorophenyl-2,3,4-tetrakis(tetrafluoro-4-pyridyl)cyclopentadiene, having pK = −5.99. Trends in the acidities of …
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Multi-component Reactions Initiated via Sonogashira Coupling
It was shown that arylbromides bearing electron-withdrawing groups in appropriate positions can be subjected to Sonogashira coupling with terminal alkynes, producing internal alkynes that can now undergo a Michael addition with suitable secondary amines. This coupling-aminovinylation sequence can …
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Heteroleptic dirhodium (II,II) complexes: synthesis, spectroscopy and applications in hydroformylation and hydroaminomethylation catalytic reactions
… model complex 1 were substituted by either the electron withdrawing CF3 (complex 2) or electron donating OMe (complex 3) groups, to observe the electronic influence on the metal complexes. As such, electroanalysis using cyclic voltammetry indicated variations in the metal-centred redox processes …
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Imidazolidinones in amine catalysis
… 2, a novel imidazolidinone containing an α-electron withdrawing group is evaluated as an asymmetric catalyst for Diels-Alder cycloaddition reactions. A substrate and reaction scope is presented and the conformational preference of the imidazolidinone is probed to rationalise the origins of …
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Chemical and electrochemical studies of Borane Anions and Metallaboranes
… indicated that when the substituent contained electron withdrawing groups (e. g. the hydrogen atoms on NCBH₂NCBH₃) the anion was static at room temperature on the n. m. r. time scale. If no electron withdrawing groups were present on the substituent then the molecule was fluxional at room …
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Temperature Programmed Desorption and Infrared Spectroscopic Studies of Interfacial Hydrogen Bonds for Small Molecules Adsorbed on Silica and Within Metal Organic Frameworks
… silica was investigated to probe the effects of electron withdrawing and donating substituents. Results indicate that the substituted benzene derivatives adsorb to silica via a cooperative effect involving SiOH---π hydrogen bonds and additional substituent-surface interactions. The strength of …
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Spectroscopy, Electrochemistry and Photochemistry of Phenylazonaphthalene Dyes
… to the phenyl ring, representing a range of electron-donating and electron-withdrawing substituents; most studies were carried out on OH-Span. A combination of UV/Visible, NMR, Raman and IR spectroscopy together with DFT calculations has shown that the dyes are planar in their stable …
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Exploring the Quinol Oxidation Mechanism at the Qo-Site of Bc1 Complex Through Site-Directed Mutagenesis
… amide groups of FL132 and FC134 give additional electron withdrawing force to the Rieske-type [2Fe-2S] cluster and the residues in the 132-134 positions play roles in anchoring the ISP to the surface of the Qo-pocket. FG133 has unique ϕ/psi angles that restrict the positions of two adjacent …
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SYNTHESIS OF PRECURSORS FOR MOLECULAR ELECTRONICS
… one of the major topics of research in molecular electronics, however the relationship between the molecular structure and the electrical characteristics of molecular rectifiers is not fully understood. To elucidate this relationship, we synthesized and examined the electrical properties of …
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The Syntheses of Bis-Guanidium Salts and Their Applications in Asymmetric Mukaiyama Type SN2 Alkylation Reactions
… were highly sterically hindered or strong electron withdrawing. Then, these chiral bis-guanidium salts were tested in asymmetric Mukaiyama type SN2 alkylation reactions as phase-transfer catalysts. Up to 86% ee was obtained, and for most of the substrates, the yields were good. Two …
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