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Applying Bayesian Machine Learning Methods To Theoretical Surface Science, Shane Carr

McKelvey School of Engineering Theses & Dissertations

Machine learning is a rapidly evolving field in computer science with increasingly many applications to other domains. In this thesis, I present a Bayesian machine learning approach to solving a problem in theoretical surface science: calculating the preferred active site on a catalyst surface for a given adsorbate molecule. I formulate the problem as a low-dimensional objective function. I show how the objective function can be approximated into a certain confidence interval using just one iteration of the self-consistent field (SCF) loop in density functional theory (DFT). I then use Bayesian optimization to perform a global search for the solution. …

N-Heterocyclic Carbene Complexes Of Ag(I) And Zr(Iv): Ag(I)-Halide Cubane Type Clusters And The Mechanism Of Hydroamination With -Nhc Pincer Complexes, Wesley D. Clark

Theses and Dissertations

The synthesis and characterization of the first series of tetra-NHC-Ag(I)-X cubane clusters are reported. The clusters were characterized with 1H and 13C NMR spectroscopy, ESI-TOF MS, and single crystal X-ray diffraction. Crossover experimental data were consistent with intramolecular exchange, which can be visualized by a molecular rotating type mechanism. Additionally, -NHC Zr(IV) pincer type complexes were synthesized and characterized with 1H and 13C NMR spectroscopy, CHN combustion analysis, and X-ray crystallography. A large rate effect was observed based on the halogen and metal center for the hydroamination/cyclization of unactivated aminoalkenes. Zirconium based pincers provided faster reaction rates than their hafnium …

Controlled Hydrosilylations Of Carbonyl Compounds And Computational Investigations Of A Hydride Shuttle Mechanism For Alkene Hydrosilylation, Gabriela Trog

Chemistry & Biochemistry Theses

Chapter 1 describes tandem dual hydrosilylations of α,β-unsaturated enals. Hydrosilylations of both carbonyl compounds and alkenes have been utilized to create chiral alcohols. Tandem dual hydrosilylations (TDH) of α,β-unsaturated carbonyl compounds create five-membered oxasilacycles that can be further converted to 1,3- diols, which are a common structural motif in the polyketide natural product family. We present preliminary data and a substrate scope for the formation of these oxasilacycles en route to the 1,3-diol compounds. Chapter 2 describes hydrosilylations of esters that result in silyl acetals. The silyl acetals are chemical synthons of the corresponding aldehyde. This reaction can be coupled …

Design, Synthesis And Applications Of Layered Double Hydroxides (Ldhs), Mixed Metal Oxides (Mmos) And Nanocomposites As Efficient Sorbents And Multi-Functional Catalysts, Madhavi N. Pahalagedara

Doctoral Dissertations

Archival abstract submitted

Interplays Of Co2, Subnanometer Metal Clusters, And Tio2: Implications For Catalysis And Co2 Photoreduction, Chi-Ta Yang

USF Tampa Graduate Theses and Dissertations

This research is motivated by two significant challenges facing the planet: reducing the emission of CO₂ to the atmosphere and production of sustainable fuels by harnessing solar energy. The main objective of this work is the study of promising photocatalysts for CO₂ reduction. DFT modeling of CO₂, subnanometer Ag&Pt clusters, and anatase TiO2 (101) surface is employed to gain fundamental understanding of the catalytic process, followed by validation using a guided experimental endeavor. The binding mechanism of CO₂ on the surface is investigated in detail to gain insights into the catalytic activity and to assist …

Metal-Ligand Cooperative Catalysis And Methods For Metal Removal From Organic Transformations, John-Paul J. Bow

Electronic Thesis and Dissertation Repository

Organometallic catalysis has revolutionized the synthesis of complex organic molecules. Methods for C-C, C-X and C-H bond formation and cleavage are exploited throughout the areas of fine chemicals synthesis, with major applications for pharmaceuticals. This situation raises duel challenges: 1) high-performance catalysts for environmentally and economically sustainable synthesis and 2) efficient methods of catalyst (i.e. metal) removal must be identified. This work tackles both of these areas. The highly tunable cooperative P^R₂N^R'₂ ligands have been implemented for the first time for catalytic organic transformations. I show that [Ru(Cp)(P^tBu₂N^Bn₂)(MeCN)][PF_{6 …}

A Study Of Allylic Aminations As Catalyzed By Heterobimetallic Pd-Ti Complexes, Diana Lauren Ellis

Theses and Dissertations

Heterobimetallic complexes present a unique approach to catalyzing challenging reactions. By having two metals in close proximity to each other, the metals are able to interact and alter their electronics in a way that simple organic ligands (carbon, nitrogen, sulfur etc.) cannot. Our studies of heterobimetallic complexes focus on a Pd–Ti complex. The complex features a dative interaction between the palladium and the titanium held together by a phosphonamide scaffold. This interaction increases the electrophilicity of the palladium and makes it a very suitable catalyst for allylic amination reactions. We have conducted extensive studies of this catalyst in allylic aminations, …

Physical Characteristics And Morphology Of Platinum Nanocrystals On Single Crystal Strontium Titanate, Joshua Gild

Theses

Eight nanometer platinum films were fabricated via electron beam deposition upon (001) strontium titanate (STO) substrates at ambient temperature then annealed at a range of temperatures in a reducing, oxidizing, or neutral environment. The evolution of platinum film dewetting and forming distinct nanocrystals was examined with XRD, AFM, and SEM. The initial deposition showed no crystallinity for the film. Upon annealing, a (001) cube on cube epitaxy was expected due to similar lattice parameters. However, an initial weak polycrystalline Pt (111) peak formed, which then transformed into (111) texture and eventually epitaxy. This (111) epitaxial relationship was observed in all …

Synthesis And Characterization Of Support-Modified Nanoparticle-Based Catalysts And Mixed Oxide Catalysts For Low Temperature Co Oxidation, Andrew Justin Binder

Doctoral Dissertations

Heterogeneous catalysts are responsible for billions of dollars of industrial output and have a profound, if often understated, effect on our everyday lives. New catalyst technologies and methods to enhance existing catalysts are essential to meeting consumer demands and overcoming environmental concerns. This dissertation focuses on the development of catalysts for low temperature carbon monoxide oxidation. CO [carbon monoxide] oxidation is often used as a probe reaction to test overall oxidation activity of a given catalyst and is an important reaction in the elimination of toxic pollutants from automotive exhaust streams. The work included here presents three new heterogeneous catalysts …

The Production Of Biobutanol From Biomass Via A Hybrid Biological/Chemical Process, Thomas Melvin Potts

Graduate Theses and Dissertations

Biobutanol use as a fuel began in the late 19th century. Problems remain in economic viability. A review of the state of the art and need for technical advances is presented.

The technical potential of producing biofuel from a naturally occurring macroalgae was studied. The algae grow in Jamaica Bay, New York City, in contaminated water. The process consisted of mechanical harvesting, drying, grinding, and acid hydrolysis to form an algal sugar solution. Clostridium beijerinckii and C. saccharoperbutylacetonicum were used in an acetone butanol ethanol (ABE) fermentation to make butanol. Fermentation was followed by distillation Butanol concentrations during fermentation reached …

A Metal-Free Approach To Biaryl Compounds: Carbon-Carbon Bond Formation From Diaryliodonium Salts And Aryl Triolborates, Kuruppu Lilanthi Jayatissa

Dissertations and Theses

Biaryl moieties are important structural motifs in many industries, including pharmaceutical, agrochemical, energy and technology. The development of novel and efficient methods to synthesize these carbon-carbon bonds is at the forefront of synthetic methodology. Since Ullmann’s first report of stoichiometric Cu-mediated homo-coupling of aryl halides, there has been a dramatic evolution in transition metal catalyzed biaryl cross-coupling reactions.

Our work focuses on the discovery and development of an unprecedented reagent combination for metal-free cross-coupling. It is hypothesized that direct carbon-carbon bond formation occurs via a triaryl-λ³-iodane and that electrophile/nucleophile pairing is critical for success in the reaction. Proof-of-concept …

Aldehydic C-H Amination Reactions Via Co(Ii)-Based Metalloradical Catalysis And Construction Of Novel Chiral Meso-Amidoporphyrin Ligands, Christopher Lee Lizardi

USF Tampa Graduate Theses and Dissertations

Medium-sized organic ring synthesis poses a seemingly insurmountable challenge, and because of this it is a field under immense investigation. Heterocyclic containing medium-sized rings are common structural motifs in nature, which has caused researchers to investigate their potential biological activity and properties as materials. This research focused on the grand challenge of medium-sized heterocyclic ring synthesis, providing the synthesis community with new tools to generate these highly evasive products, while elucidating energetic and geometric properties of one of Nature's least understood organic ring systems.

Cobalt(II)-Amidoporphyrins, [Co(D₂-Por)], are an emerging class of metalloradical catalysts (MRC) which can facilitate …

X-Ray Characterization Of Platinum Group Metal Catalysts, Eric Peterson

Nanoscience and Microsystems ETDs

Platinum group metals (PGMs) are used extensively as catalysts, employed in several sectors of the world energy economy. Fuel cells employing PGM catalysts show promise as power sources in the proposed hydrogen economy, using alcohols as hydrogen storage media. Currently, the most economically important application for PGMs is for the mitigation of emissions from internal combustion engines via catalytic converters. In all applications, efficient use of these expensive metals to fabricate robust catalysts is of the utmost importance. Understanding the catalyst structure/property relationship is the key to the improvement of existing catalysts and the discovery of new catalysts. For example, …

Investigating The Synthesis Of Heterocycles Via Gold Catalyzed Cyclizations And Cyclo-Dehydrating Reactions, Katherine L. Childers

Undergraduate Honors Thesis Projects

The goal of this project was to study novel synthetic procedures for heterocycles. This was achieved through a two-part investigation. In the first part, a variety of conditions for the gold catalyzed cyclization of allenes were studied. This work was focused on the lesser studied intermolecular reactions of allenes. A variety of allenes were synthesized, and then reacted with 1,3-dipoles and a gold catalyst. These reactions were determined to be unsuccessful through the analysis of nuclear magnetic resonance spectroscopy data. In the second part of this study, the synthesis of 1,3,4-oxadiazoles was investigated. Several cited procedures were examined to determine …

The Synthesis Of Solid Supported Palladium Nanoparticles: Effective Catalysts For Batch And Continuous Cross Coupling Reactions, Kendra W. Brinkley

Theses and Dissertations

Catalysis is one of the pillars of the chemical industry. While the use of catalyst is typically recognized in the automobile industry, their impact is more widespread as; catalysts are used in the synthesis of 80% of the US commercial chemicals. Despite the improved selectivity provided by catalyst, process inefficiencies still threaten the sustainability of a number of synthesis methods, especially in the pharmaceutical industry. Recyclable solid supported catalysts offer a unique opportunity to address these inefficiencies. Such systems coupled with continuous synthesis techniques, have the potential to significantly reduce the waste to desired product ratio (E-factor) of the production …