Inorganic Chemistry Commons^™

In-Situ Imaging Of Surface Heterogeneity In Semiconductor Photocatalysts Using Singlemolecule Fluorescence Microscopy, Meikun Shen

Arts & Sciences Electronic Theses and Dissertations

Metal oxide semiconductors have been used as promising photocatalysts to convert solar energy into useful fuels, such as water splitting, carbon dioxide reduction, and nitrogen fixation reactions. However, the typical metal oxide photocatalysts' efficiency often suffers from their weak visible light absorption and low charge carrier mobilities. One common strategy to mitigate these limitations is to introduce oxygen vacancies into the lattice of the semiconductor photocatalysts. This strategy has been applied to many metal oxide photocatalysts, such as titanium oxide, tungsten oxide, and zinc oxide, and oxygen vacancies indeed enhance their catalytic activities. Various roles of oxygen vacancies have all …

Cu-Promoted C-H Bond Hydroxylation Inspired By Cu-Dependent Metalloenzymes, Rachel Trammell

Chemistry Theses and Dissertations

From 2003 to 2015, Schӧnecker and Baran proposed a dinuclear Cu/O₂ species in their mechanistic proposal for the hydroxylation of sp³ C-H bonds within their systems (proposed based on yields). Inspired from the site selectivity of this methodology and poor analysis of the mechanism, the first project was inspired to re-examine the sp³ C-H bond hydroxylation by Schrӧnecker and Baran and perform an intensive investigation into understanding how Cu/O₂ interact which led us to propose a new mechanism based on the evidence collected (i.e., LCu^II-hydroperoxide species that undergoes homolytic O-O bond cleavage). From there …

Suzuki Coupling Catalyzed By (8-(Dimesitylboryl)Quinoline)Palladium(0) Species: A Theoretical Analysis, Haley S. Rust

Honors Thesis

The Suzuki reaction is a catalyzed cross-coupling reaction which is of upmost importance in the formation of carbon-carbon (C-C) bonds in modern organic synthesis. Recently a new catalyst including an 8-(dimesitylboryl)quinoline for the coupling of aryl halides with phenylboronic acids was synthetized. We synthesized ligand that includes a frustrated Lewis pair, (quinolin-8-yl)dimesitylborane (DMBQ), complexed it with group X metals (nickel (Ni), palladium (Pd), and platinum (Pt)), and studied the process of oxidative addition with carbon-fluorine (C-F) bonds and activation towards Suzuki coupling. Mayer bond analysis and electron localization function maps showed a bond between the boron center in the ligand …

Computational And Experimental Studies Of Functionalized Phenolic Tertiary Phosphine Oxides As Organocatalysts For The Redox-Neutral Mitsunobu Reaction, Sadie Brown

Electronic Theses and Dissertations

The purpose of this thesis was the identification of a more efficient catalyst analog that could perform the redox-neutral Mitsunobu reaction, which was achieved via two synthetic pathways: elimination-addition and addition-rearrangement. Furthermore, a computational investigation was conducted on the conflicting interpretations of the catalytic cycle. Our research group replicated Houk et al. work, as well as expanded the computations to examine the influence different functional groups had on the ground state and transition state structures. Important ground state and transition state structures were determined, which provided a more energetically favorable pathway of the catalytic cycle. Experimental work demonstrated that both …

Structure Determination Of Pd2sin (N = 1 - 9) Clusters, Ryan Carlin

Honors College Theses

The geometry and relative stability of small Pd2Sin (n = 1 - 9) clusters are determined using the B3LYP hybrid density functional theory method. Candidate structures are identified by the utilization of unbiased global optimization procedures. From the lowest energy geometries, binding energy, fragmentation energy, second-order energy difference, and frontier orbital gap energy are calculated to determine cluster stability. Pd2Sin (n = 8 and 9) adapts new lowest energy geometric configurations that have previously not been considered. Pd2Si5 is determined to have a high relative stability of the clusters within this size range.

A Conductivity Analysis Of A Newly Synthesized Poly(Ethylene Glycol) Methyl Ether Hydroxide Electrolyte, Sarah Marie Peterson

Honors Theses

This thesis investigates the synthesis and conductive properties of a Poly (ethylene glycol) methyl ether-based polymer electrolyte. The goal of the synthesis is to enhance the hydroxide ion conduction properties of the polymer with its cationic groups attached. The MePEG backbone contained seven ethylene glycol groups and was modified to substitute the hydroxide group in the MePEG with trimethylamine. In addition, the bromide added in the synthesis was exchanged for hydroxide ions to allow for the transportation of hydroxide ions in polymeric electrolytes that can be used in Anion Exchange Membrane Fuel Cells. The newly synthesized polymer was compared to …

Synthesis Of A Zinc Dipyrrin Complex For Photocatalytic Reduction Of Co2, Sylvia Meredith

Undergraduate Honors Theses

Zinc dipyrrin complexes have the potential to act as cheap, effective photosensitizers. Synthesizing and studying different types could lead to more efficient solar energy harvesting processes, especially the production of solar fuel. Here, two attempts to synthesize 1,3,7,9-tetraphenyl-5-mesityldipyrromethene are reported and discussed. According to ¹H NMR, the first synthesis attempt was not successful. The second synthesis attempt was not purified effectively, so ¹H NMR produced inconclusive results. Further purification strategies or alternate synthesis methods are required.

Application Of Titrations For Verification Of Small Molecule Interaction In Relation To Amidoximated Fibers For Uranium Extraction From Seawater, Kc Michael Mote

Masters Theses

Nuclear energy is a promising substitute for fossil fuels due to possessing low carbon emissions and providing scalable base-load power. However, one major drawback of using nuclear fuel as an energy source is that it needs a steady source of uranium. While the most economical method of obtaining uranium is through conventional terrestrial mining of the ore uranite, mining uranium ores is both harmful to the environment and limited by the terrestrial uranium supply, which is estimated at only 100 more years. However, more than 1000× more uranium is dissolved in seawater than is reasonably inferred and assured in terrestrial …

Investigating The Role Of Charge Separation In Triplet State Formation In Zinc Dipyrrin Photosensitizers, Irene Y. Dzaye

Electronic Theses and Dissertations

About 85% of the world’s energy is derived from non-renewable sources—coal, petroleum, and natural gas. Solar photocatalysis is one way to potentially generate cheap renewable fuels by harnessing energy from the sun using a photosensitizer and converting it into chemical energy. The efficiency of a photosensitizer depends on its capacity to form a prolonged triplet excited state. Zinc dipyrrin complexes have the potential to be efficient sensitizers for reductive photochemistry, but their ability to form long-lived triplet excited states still needs extensive research. The overall aim of this research is to probe the role charge separation plays in the formation …

Progress Towards Synthesis And Characterization Of Bay-Annulated Indigo Chromophores, Katherine Weiss, Denise Femia

HON499 projects

Through acetylation, N,N’-diacetylindigo was synthesized from indigo. N,N’-diacetylindigo and 2-thiopheneacetyl chloride were combined in an attempt to synthesize 7-thiophenyl bayannulated indigo (BAI). After 1H NMR characterization, it was found that the product was not 7-thiophenyl BAI. A previously synthesized sample of 7-phenyl BAI was purified. UV-VIS absorbance, fluorescence, IR, and 1H NMR were used to characterize the compounds.

Synthesis And Characterization Of Mps And Mes Capped Cdse Nanoparticles, William Josul

Ramaley Celebration

Over the past several years, interest in nanoparticle-derived solar cells has increased. This is due to their low material cost, high-potential efficiency, and desirable and tunable optical properties. Using biphasic ligand exchanges, sodium 3-mercapto-1-propanesulfonate (MPS) and sodium 2- mercaptoethanesulfonate (MES) were successfully exchanged as ligands with oleic acid to create particles that have a higher propensity to move charge in a solar cell. MES and MPS were chosen as ligands due to being shorter and less insulating than oleic acid. The initial as-synthesized CdSe-OLA, and the nanoparticle products of the two ligand exchanges were confirmed by 1H NMR, UV-Vis, and …

Synthesis And Catalytic Oxidation Of Organic Substrates By Light-Harvesting Metalloporphyrins, Christian Alcantar

Masters Theses & Specialist Projects

note: Some notation in this abstract may not appear exactly as formatted in the thesis.

In this work, ruthenium, iron, and manganese light-harvesting metalloporphyrins have been successfully synthesized to serve as biomimetic models of the active site of Cytochrome P450 for the development of a green and efficient oxidation catalyst. The covalent introduction of light-harvesting boron-dipyrrin (BODIPY) fluorophores on the porphyrin macrocycle allows for the absorption of a broader range of visible light in addition to that captured by the porphyrin aromatic system alone. It is expected that this core-antenna system will increase the absorbed light energy and transfer it …

Visible Light Generation And Mechanistic Investigation Of High-Valent Metal-Oxo Species Supported By Different Ligands, Seth Ellis Klaine

Masters Theses & Specialist Projects

Numerous transition metal catalysts have been designed as biomimetic model compounds for the active site of metalloenzymes found throughout Nature, most notably cytochrome P450 monooxygenases that carry out the oxidative transformations of organic substrates with near-perfect chemo-, regio-, and stereo-selectivity. The primary active oxidants in catalytic and enzymatic cycles are fleeting high-valent metal-oxo intermediates where the oxo ligand can transfer to an organic substrate in a process known as oxygen atom transfer (OAT).

In the present work, porphyrin-manganese(III), salen-chromium(III), and salenmanganese( III) derivatives were successfully synthesized and spectroscopically characterized using 1H NMR and UV-Vis spectroscopies. A facile photochemical approach was …

Characterization Of Uranium, Lead, And Rare Earth Element Pollution In Natural Soils And Sediments, Hope Rasmussen

Civil and Environmental Engineering Theses and Dissertations

Heavy metals in the environment add to the global burden of pollution, negatively impacting public health and ecosystem resilience. This study included projects regarding uranium (U), lead (Pb), and rare earth elements (REE) in natural samples, due to their known toxicity, ubiquity, and relevance in context to recent pollution trends. The first project focused on testing the potential of using a hydroxyapatite product as a remediation solution for U-contaminated groundwater and soil at an EPA Superfund site. The results showed that the U was sequestered in a highly crystalline mineral form within the solids, guiding the EPA to specify the …

Competitive Reductive Removal Of Chromate And Pertechnetate Via Zero-Valent Iron, Jonathan Williams Ramirez

FIU Electronic Theses and Dissertations

Treatment to immobilize radioactive waste is of concern for long-term storage, avoiding future environmental exposure. Most production of Technetium-99 (⁹⁹Tc) occurred as a byproduct of development of legacy nuclear weapons research. Zero-valent iron (ZVI) is a promising reductant of Tc(VII) to a less mobile ⁹⁹Tc(IV). However, more redox-sensitive contaminants can compete in the reductive process. Therefore, it is important to examine the effects of competitive contaminants and quantify the effects on the reductive removal rates of ⁹⁹Tc. Chromate, Cr(VI), is a redox-sensitive contaminant that is expected to be present in legacy waste present in the Hanford …

Uranium Fate And Mineral Transformations Upon Remediation With Ammonia (Nh3) Gas, Silvina A. Di Pietro

FIU Electronic Theses and Dissertations

The fission of uranium (U) for plutonium production was a major activity at the U.S. Department of Energy’s (DOE) Hanford Site in Washington State during World War II and Cold War. This endeavor resulted in the generation of over two million liters of high-level radioactive waste, most of which still remains in 177 underground storage tanks. Due to the improper storage and aging of these tanks in addition to other waste releases across the Site, approximately 200,000 kg of U have been released into the vadose zone. The objective of this study was to determine whether the application of the …

Interactions Of Organic Fluorophores With Plasmonic Surface Lattice Resonances, Robert J. Collison

Dissertations, Theses, and Capstone Projects

It is common knowledge that metals, alloys and pure elements alike, are lustrous and reflective, the more so when a metal surface is flat, polished, and free from oxidation and surface fouling. However, some metals reflect visible light, in the 380 nm to 740 nm range of wavelengths, much more strongly than others. In particular, some metals reflect wavelengths in certain portions of the ultraviolet (UV), visible, and near-infrared (NIR) regime, let us say 200 nm to 2000 nm, while absorbing light strongly in other segments of this range. There are several factors that account for this difference between various …

Coastal Watershed Monitoring And Management: Geomorphology, Geochemistry, And Hydrologic Modeling Of Los Peñasquitos Creek, Ca, Ravleen Khalsa-Basra

Theses

Rivers in semi-arid climates are directly influenced by local geographic and hydrologic conditions and impacted by modifications to hydrology via urbanization. Changes can influence erosion, morphology, habitat sustainability, and watershed health. In highly urbanized southern California coastal regions, these rare open spaces provide vital ecosystem services. Los Peñasquitos Creek in San Diego County is one such watershed. Using stream surveying and laboratory methods we quantified channel characteristics, grain size distribution, total metal concentration [M], organic carbon (%OC), and phosphate to longitudinally characterize the creek for improved management. Results identified three distinct reaches in the watershed (upper, middle, lower). Downstream, depth …

Water Spines And Networks In G-Quadruplex Structures, Kevin Li , '22, Liliya A. Yatsunyk, S. Neidle

Chemistry & Biochemistry Faculty Works

Quadruplex DNAs can fold into a variety of distinct topologies, depending in part on loop types and orientations of individual strands, as shown by high-resolution crystal and NMR structures. Crystal structures also show associated water molecules. We report here on an analysis of the hydration arrangements around selected folded quadruplex DNAs, which has revealed several prominent features that re-occur in related structures. Many of the primary-sphere water molecules are found in the grooves and loop regions of these structures. At least one groove in anti-parallel and hybrid quadruplex structures is long and narrow and contains an extensive spine of linked …

Functionalization Of Novel Pp5 Inhibitors, Hope P. Hill

Undergraduate Theses

The overexpression of protein phosphatase 5 has been correlated to tumor cell reproduction making it a candidate for small molecule drug therapy. Selective and potent inhibition of protein phosphatase 2A (PP2A) enzyme has been previously achieved through the development of the molecule fostriecin with key functionality being a lactone and unsaturated linear chain. The large synthetic overhead of fostriecin has led to exploration of other small molecule inhibitors that could mirror fostriecin’s interaction with the active site in the catalytic domain of PP5. The naturally occurring inhibitor, cantharidin, is functionalized with an epoxy containing eleven carbon chain to optimize binding …