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 24 for “"Electron-Withdrawing Substituents"”.
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Investigation of the steric and/or electronic effects associated with the (1,5)-sigmatropic rearrangement of 1-substituted-2,3,4,5-tetraphenyl- 2,4-cyclopentadien-1-ols
… It was determined that the steric and electronic nature of the migrating groups played a predictable role in the [l,5]-sigmatropic rearrangement of these compounds. Electron donating groups increased the rate of migration whereas electron withdrawing substituents were responsible for …
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Molecular electrocatalysis of hydrogen evolution: catalytic design studied by density functional theory
… with respect to the Hammett constant 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 …
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Isotopic labelling applied to the infrared spectra of metal complexes
… resulting from introduction of a variety of substituents into the pyridine ring are discussed on the basis of the electronic effects of the substituents. After allowing for mass effects, electron-withdrawing substituents are found to decrease νNi-N frequencies while electron-releasing …
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The sodium borohydride reduction of organic halides and related derivatives in aprotic solvents
… benzyl chlorides revealed that the electronic effects of groups ranging from p-methoxy to p-nitro had a rather small effect on the rate of reduction. Aryl halides arc reduced by sodium borohydride in yields dependent upon the particular halogen involved, the presence of other ortho …
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Development of Earth Abundant Metal-Catalyzed Reactions to Construct Heterocycles
… the reaction is broad and tolerates a range of electron-releasing or electron withdrawing substituents on the nitroarene, and the ortho-substituent can be modified to construct benzoxazines, dihydro benzothiazines, tetrahydroquinolines, tetrahydroquinoxalines, or tetrahydrobenzo-oxazepines. A …
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Synthesis and photophysical investigation of supramolecular complexes developed for photoinitiated electron collection
… devices were designed to perform photoinitiated electron collection. These devices were synthesized, characterized and their spectroscopic, photochemical and electrochemical properties investigated. The general formula for these systems is {[(bpy)₂Ru(BL)]₂MCl₂}⁵⁺ (M = Ir<sup>III</sup> and BL = …
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Synthetic studies of sodium aminodiboranate salts with electronwithdrawing substituents
… inductive, and hyperconjugative effects of the substituents on nitrogen are all in competition in these systems. In chapter 2 we describe the preparation of fluorinated aminodiborantes, although here the longer reaction times required for their synthesis lead to undesirable production of …
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Novel palladium-catalyzed synthesis of 3-substituted indoles and its application toward the total synthesis of indolactam V
A novel synthesis of indoles having electron withdrawing substituents in the 3-position has been developed. Various 2-nitrostyrenes were prepared via Stille coupling of 2-tributyl stannyl-2-propenoic acid ethyl ester with substituted 2-bromo-l-nitrobenzenes. Alternatively, sequential vicarious …
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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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Volatile metal borohydride complexes: synthesis and characterization of new chemical vapor deposition precursors
… sodium aminodiboranates with sterically bulky or electron withdrawing substituents on nitrogen has been achieved by the treating amine-borane with either BH3•THF or by thermolysis at elevated temperatures followed by the addition of BH3•THF, which produced µ-aminodiborane. The µ-aminodiborane can …
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Part I: Palladium PEPPSI-IPENT CI, A Useful Catalyst for Challenging Amination Reactions Part II: Generation Of Benzynes in Flow Reactors followed by Subsequent Diels-Alder Reactions
… these couplings. The steric bulk of the 3-pentyl substituents on the aryl rings of the NHC ligand that drives the cross-coupling by facilitating reductive elimination also mitigates the poisoning effect of the 2-aminopyridine functionality in the starting material/and or products. We also found …
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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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BINDING ENERGIES AND SOLVATION OF ORGANIC MOLECULAR IONS, REACTIONS OF TRANSITION METAL IONS WITH, AND PLASMA DISCHARGE IONIZATION OF MOLECULAR CLUSTERS
… the pyrimidine is reported here. The effect of substituents on substituted-benzene cations on their solvation by an HCN solvent was also investigated using ion mobility mass spectrometry and DFT computations were also investigated. We looked at the effect of the presence of electron-withdrawing …
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Synthesis, evaluation, and applications of hydrogen sulfide-releasing supramolecular materials
… relationships with SATO ring substituents playing a crucial role in hydrolysis rates. Electron-donating substituents accelerate the rate of hydrolysis while electron-withdrawing substituents slows it down. We also explored their hydrolysis mechanisms at different pH values. …
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Thermal cis-trans isomerization of azobenzene studied by path sampling and QM/MM stochastic dynamics
… can be induced via transitions to excited electronic states and fine-tuned by a large number of different substituents at the phenyl rings. But a rational design of tailor-made azo groups also requires control of their stability in the dark, the half-lifetime of the cis isomer. In …
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Non-Covalent Interactions in Water Using Synthetic and Biological Receptors
… of the aromatic interactions show that electron-withdrawing substituents increase the strength of the interactions by a factor of up to 20, highlighting the role of electrostatics in stabilising both the edge-to-face and stacking interactions. The effect of introducing a heteroatom …
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Mass spectrometry of substituted benzils
… that all parent-molecule ions are formed by electron capture, and all fragments by dissociative-attachment. The electron-withdrawing substituents cause a broadening of the ionization efficiency curve for the parent-molecule ion; all other substituents have no effect on the curves' shape. …
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Application of natural dyes in textile industry and the treatment of dye solutions using electrolytic techniques
… decreasing order: NB ≈ NR > AO ≈ RS. Strongly electron withdrawing substituents such as nitro group or carbonyl group increases the degradation of the phenothiazine chromophore, whereas the electron donating groups such as amino and alkyl amino groups decrease the degradation. Anodic oxidation …
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Palladium-catalyzed reactions of ammonia, carbon monoxide, and cyanide
… arylpalladium cyanide complexes reveal that the electronic effects on the reductive elimination from arylpalladium cyanide complexes are distinct from those on reductive eliminations from arylpalladium alkoxo, amido, thiolate, and enolate complexes. Arylpalladium cyanide complexes containing aryl …
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Redox-Active Trivalent Metallosurfactants With Low Global Symmetry For Molecule-Based Electronics: Spectroscopic, Electrochemical, And Amphiphilic Properties Of New Molecular Materials For Current-Voltage Measurements In M|lb-Monolayer|m Devices
… of Philosophy</p> <p> The silicon-based microelectronic industry has made remarkable technological advancements. Among these, new generation consumer electronics, telecommunication devices, and high performance data processing smart devices are of special interest. At present, electronic …
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