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Full-Text Articles in Physical Sciences and Mathematics
Computational Quantum Chemistry Studies Of The Stabilities Of Radical Intermediates Formed During The Oxidation Of Melatonin, Constance E. Warden
Computational Quantum Chemistry Studies Of The Stabilities Of Radical Intermediates Formed During The Oxidation Of Melatonin, Constance E. Warden
Electronic Theses and Dissertations
Melatonin, a nontoxic natural antioxidant, is of interest as a possible spin trap for use in spectroscopic methods to observe and identify short-lived free radicals, which have been linked to oxidative stress that may result in serious health problems. However, the reaction mechanisms for the oxidation of melatonin to form the product N1-acetyl-N2-formyl-5-methoxykynuramine are still not well understood. Computational quantum chemistry studies have been done on four proposed reaction mechanisms, involving the following major intermediate structures: a dioxetane, an epoxide, a melatonin radical cation, and a spin radical adduct. Molecular geometries were optimized at the …
Computational Studies On Mechanisms And Reactivity Of Mercury And Cobalt Organometallic Reactions, Jack Terrell Fuller
Computational Studies On Mechanisms And Reactivity Of Mercury And Cobalt Organometallic Reactions, Jack Terrell Fuller
Theses and Dissertations
Density Functional Theory (DFT) is a powerful tool for treating large organometallic structures efficiently and accurately. DFT calculations on the Hg-catalyzed oxidation of methane to methyl bisulfate in sulfuric acid suggest the lowest energy pathway involves a closed-shell electrophilic C–H activation mechanism coupled with metal alkyl reductive functionalization and oxidation by SO3. Comparison to Tl, Zn, and Cd suggests that Hg is unique in its ability to catalyze this set of reaction steps. Comparison to K2S2O8 highlights the selectivity of this C–H activation reaction as opposed to radical conditions. In contrast, DFT calculations indicate that CoIII(TFA)3 oxidizes methane through a …
Benchmarking Ab Initio Computational Methods For The Quantitative Prediction Of Sunlight-Driven Pollutant Degradation In Aquatic Environments, Kasidet Trerayapiwat
Benchmarking Ab Initio Computational Methods For The Quantitative Prediction Of Sunlight-Driven Pollutant Degradation In Aquatic Environments, Kasidet Trerayapiwat
Honors Projects
Understanding the changes in molecular electronic structure following the absorption of light is a fundamental challenge for the goal of predicting photochemical rates and mechanisms. Proposed here is a systematic benchmarking method to evaluate accuracy of a model to quantitatively predict photo-degradation of small organic molecules in aquatic environments. An overview of underlying com- putational theories relevant to understanding sunlight-driven electronic processes in organic pollutants is presented. To evaluate the optimum size of solvent sphere, molecular Dynamics and Time Dependent Density Functional Theory (MD-TD-DFT) calculations of an aniline molecule in di↵erent numbers of water molecules using CAM-B3LYP functional yielded excited …
Optimizing Protocols For Carbohydrate Nmr Chemical Shift Computations, Michael Trent Kemp
Optimizing Protocols For Carbohydrate Nmr Chemical Shift Computations, Michael Trent Kemp
USF Tampa Graduate Theses and Dissertations
The spectroscopic analysis of cellulose is experimentally challenging while computationally accessible with recent developments in NMR code. However, prior to using density functional theory to calculate the NMR chemical shifts of cellulose, smaller, sugar-like molecule systems need to be benchmarked against experimental values. The quantum mechanical / molecular mechanical (QM/MM) calculations presented herein utilize six test systems: ethanol, pyridine, pyrrolidine, pyrrole, myo-inositol and scyllo-inositol in conjunction with the reference tetramethylsilane used to scale the calculated isotropic shielding tensors to relative chemical shifts. The effect of solvent on calculated NMR chemical shifts has also been investigated with regard to quantity of …