Chemistry Commons^™

The Photophysical Studies Of Transition Metal Polyimines Encapsulated In Metal Organic Frameworks (Mof’S), Jacob M. Mayers

USF Tampa Graduate Theses and Dissertations

Light harvesting systems provide a platform that converts solar energy into other forms of energy. One of the most common examples of photon capturing and conversion into chemical energy is observed in photosynthetic organisms in both Eurkaroyic and Prokaryotic domains. Nature provides a model for successful light harvesting platforms which includes the compartmentalization of antenna complexes that contain separated donor and acceptor pairs that participate in efficient electron transfer processes. In order to mimic such systems, crystalline porous materials that exhibits regular cavities and pore dimensions provides an excellent starting place. Metal organic frameworks (MOFs) are a class of porous …

Investigating Cathode Dissolution By Homogenous Sol-Gel Coating On Manganese Dioxide Nanofibers To Extend Battery Performance, Milan Haddad

Symposium of Student Scholars

The cathode dissolution is a known phenomenon for manganese dioxide (MnO₂) based cathode materials in both aqueous and non-aqueous batteries. Upon battery discharge, reduced Mn³⁺ species disproportionate (2Mn³⁺→ Mn⁴⁺ + Mn²⁺) and Mn²⁺ dissolves into the electrolyte causing the loss of active material. While MnO₂ is a promising cathode for rechargeable aqueous zinc ion batteries (ZIB) due to its availability and low toxicity, the electrochemical performance is limited during battery cycling due to the dissolution of the cathode. In this work, a homogeneous sol-gel SiO₂ coatings with various thicknesses …

Activated Carbon Pore Expansion Using Acidic Hydrothermal Method, Max Thompson

Symposium of Student Scholars

Petroleum Coke is a widely abundant, high carbon content material produced as a byproduct of the oil refining process. Its abundance makes the price per ton low and it is produced in almost all regions of the world. Due to the low price and high carbon percentage, commercial companies make large amounts of activated carbon using petroleum coke as a precursor. These activated carbons are characterized by their high surface area and can achieve widely varying pore morphology with different activation processes. The goal of this work is to achieve a homologous mesopore activated carbon material for use in super …

Design And Development Of 2d Functional Semiconductor Nanocrystals, Andrew Hunter Davis

Dissertations - ALL

Anisotropic nanocrystals (NCs) have become of keen interest in recent years, especially for applications in optoelectronic devices due to their directionally oriented emissions, narrow emission spectra, and suitable morphologies for device integration. Of the desired anisotropic NCs, two-dimensional (2D) NCs are of profound interest, due to their impressive optical and electronic properties as well as their prospective advantages towards applications in layered optoelectronic devices, such as solar cells. However, 2D NCs face many challenges, including limited synthetic derivation, as well as decreased stability and optical response, due to their large surface-to-volume ratio and reactive planar surface increasing surface defect state …

Chemistry Card Games - Games For Learning And Enjoying Chemistry, Michelle M. Clark

Sabbatical Projects

Many chemistry students struggle due to a lack of basic math skills. My goal over sabbatical is to develop active learning modules that improve math literacy. I will be collaborating with Dr. Joan Cotter, a renowned math curriculum author whose comprehensive math program utilizes an innovative approach that could benefit chemistry students who have poor math literacy.

Exploring Electron-Sink Behaviors Of Molecular Assemblies, Yume Mai

Boise State University Theses and Dissertations

Metal carbonyl clusters, such as the [Ni₃₂C₆(CO)₃₆]^6- anion, have been documented to display electron-sink phenomena. However, such large clusters suffer from inefficient yields due to their demanding and unreliable synthesis routes. To approach this obstacle, we investigated the electrochemical properties of Fe₂(μ-PPh₂)₂(CO)₆, an organometallic complex known to experience a reversible two-electron transfer process. In this work, we report a modular synthetic strategy for expanding the electron-sink capacity of molecular assemblies by installing Fe₂(μ-PPh₂)₂(CO)₆ redox mediators to arylisocyanide ligands. …

Synthesis, Characterization, And Catalytic Activity Of Functionalized Metal Bis(Thiosemicarbazones)., Caleb Aaron Calvary

Electronic Theses and Dissertations

Bis-(thiosemicarbazones) are a class of ligands that have found a wide range of uses from electrocatalysts to medicinal and diagnostic reagents. These ligands contain a diimine backbone, N₂S₂ chelating core, and pendent amines. In order to further explore this class of ligands, the previously underreported transamination reaction, which exchanges one pendent amine group for another, was utilized to create several derivatives using aliphatic and aromatic amines. The transamination reaction is appealing alternative to making the desired thiosemicarbazide. Further appeals come from the fact that it is a one-pot reaction that gives highly pure products in good yields. …

Laboratory Investigation Of Cyanide Evolution During Reaction Between Hypochlorous Acid And Glycine, Luz Chavez

Electronic Theses, Projects, and Dissertations

Fresh water treatment and conservation is of great importance in a society with a growing population. Ensuring water safety is a crucial task for water treatment plants. Advances in science and technology have allowed for the testing and study of potentially harmful side substances produced by water sanitation methods, one of those substances is cyanide (-CN). Previous research correlated a significant increase of cyanide levels in effluent water sanitized with a chlorination method. Research has also proposed a mechanism for the formation of cyanogen chloride (CNCl) from reactions with amino acids during the chlorination process. Flow injection analysis was chosen …

Desorption Of Non-Exchangeable Radiocesium In Soil From Fukushima Prefecture, Japan, Grayson Phillips

Master of Science in Chemical Sciences Theses

The Fukushima Daiichi Nuclear Powerplant was struck by an earthquake and a tsunami resulting in the meltdown of four of the six reactor cores operating at the plant. As a result, nuclear waste was released from the plant, contaminating the soil in the region. Most of the contamination was sequestered within the few inches of the soil but unluckily the contamination, radiocesium formed a non-exchangeable bond. The Japanese government bagged this soil and has stored it in fields surrounding the exclusion zone. Long-term storage facilities have not been determined. This is a study of the available resources to determine if, …

Bridging The 12-6-4 Model And The Fluctuating Charge Model, Pengfei Li

Chemistry: Faculty Publications and Other Works

Metal ions play important roles in various biological systems. Molecular dynamics (MD) using classical force field has become a popular research tool to study biological systems at the atomic level. However, meaningful MD simulations require reliable models and parameters. Previously we showed that the 12-6 Lennard-Jones nonbonded model for ions could not reproduce the experimental hydration free energy (HFE) and ion-oxygen distance (IOD) values simultaneously when ion has a charge of +2 or higher. We discussed that this deficiency arises from the overlook of the ion-induced dipole interaction in the 12-6 model, and this term is proportional to 1/r …

Structure And Reactivity Of The First Row Transition Metals Bearing Redox-Active Ligands And Tunable H-Bonding Interactions, Khashayar Rajabimoghadam

Chemistry Theses and Dissertations

Metalloenzymes, as natural catalysts, can break a reaction with high activation energy to multiple small reactions with lower activation energies; in these small reactions, multiple bonds form and dissociate rapidly, some metalloenzymes use redox-active ligands in their active site to provide the needed electrons for these multiple small reactions. Additionally, in the secondary coordination sphere in the vicinity of the metalloenzymes, the hydrogen bonding interactions facilitate the transfer and interaction of the substrates and the stabilization of the active intermediates. These unique features in metalloenzymes inspired chemists to design molecular models that can partially mimic the structure and reactivity of …

Tellurorhodamine Photocatalysts In Aerobic Oxidation Reactions: Development Of Synthetic Methods And Reaction Mechanisms, Irving D. Rettig

Dissertations and Theses

Aerobic oxidation photocatalysis involves the use of oxygen as an oxidant species, coupled to a light driven catalyst to achieve useful chemical transformations. Catalytic aerobic oxidation reactions can be defined as either oxidase-like, in which O₂ acts as an electron donor/acceptor but is not incorporated into the reaction products, or oxygenase-like where O₂ acts as an electron donor/acceptor and is incorporated into the reaction products. A multitude of inorganic catalysts have been developed that can achieve a wide scope of oxidase-like or oxygenase-like reactivity, however, it is rare for a catalyst to be capable of both. We report …

The Reactivity Of Metal Phosphites: Oxidative Rate Analysis, Jamie Kitchens

Symposium of Student Scholars

Phosphorous compounds are involved in many of the biomolecular processes deemed fundamental for life. DNA, ATP, and phospholipids are a few of the molecules where phosphates can be found in the body. Phosphates are geochemically characterized by their low solubility and poor reactivity. This has led to the investigation of reaction mechanisms that could lead to the formation of the phosphorous compounds found in organisms. The oxidation of phosphite into phosphate could be how phosphates were introduced to life, due to phosphites being more soluble and more reactive than phosphates. We will present the synthesis and oxidation reactivity of four …

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.

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.

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 …

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 …

Studies Of The Rectification Behavior Of The Pdt Ligand And The Active Site Of Msrp, Laura J. Ingersol

Chemistry and Chemical Biology ETDs

Molybdenum (Mo) is an essential element that plays an important role in global nitrogen, carbon, and sulfur cycles with a critical role in human metabolism and ecological balance. It becomes catalytically active when complexed with the pyranopterin dithiolene ligand (PDT), forming the nearly ubiquitous molybdenum cofactor (Moco). The complex biosynthetic pathway of Moco, its presence in all three domains of life, and its role as a constituent cofactor in the last universal common ancestor (LUCA) all point toward the importance of the PDT in the development of life on Earth. Molybdoenzymes catalyze the two-electron oxidation or reduction of substrates that …

Theoretical Investigation Of In2h2 And Tl2h2 And Their Relationship To Other Group 13 Metal Dihydrides, Caroline Sargent

Student Scholarship

Four constitutional isomers{ dibridged, monobridged, vinylidene-like, and trans{ of group 13 metal dihydrides have been reviewed and studied by theoretical methods. Equilibirum structures, relative enthalpies, and vibrational spectroscopic information is presented for isomers of Al2H2, Ga2H2, In2H2, and Tl2H2. Properties of the isomers of Al2H2 and Ga2H2 were obtained from previous studies.1{3 Properties of In2H2 and Tl2H2 were calculated using rigorous ab initio theory, and the results are presented. …

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 …

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 …

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 …

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 …

Synthesis And Reactivity Of Metal Bis(Alkoxide) Complexes In Nitrene Coupling And Polymerization Of Polar Monomers, Duleeka Chamini Wannipurage

Wayne State University Dissertations

The nitrene homocoupling to produce azoarenes was done using two different iron (II) alkoxide complexes, Fe(OCtBu2(3,5-Ph2C6H3)2(THF)2 and Fe[OO]Ph(THF)2. Due to the steric bulkiness of HOCtBu2(3,5-Ph2C6H3 ligand, this complex exhibited selectivity for the bis(alkoxide) ligation; no tris(alkoxide) complexes were observed. As a result, both bulky and non-bulky aryl nitrenes are coupled with Fe(OCtBu2(3,5-Ph2Ph)2(THF)2, albeit the coupling of the less bulky substrates requires higher temperatures and longer reaction times. Stoichiometric reactions of Fe(OCtBu2(3,5-Ph2C6H3)2(THF)2 with non-bulky aryl azides led to the observation of the iron(III) tetrazene radical anion complexes, that can produce azoarene products after heating. Tetrazene complexes likely serve as a “masked …

Thermal Atomic Layer Deposition Of Titanium Nitride Films: Synthesis And Characterization Of Novel Titanium Precursors, Anuththara Chalani Upeksha Abesinghe Arachchige

Wayne State University Dissertations

Due to the continuous miniaturization of microelectronic devices, robust deposition techniques are required which can provide continuous and conformal thin films even in high aspect ratio structures. Atomic Layer Deposition (ALD) is an excellent choice of deposition technique as it is capable of providing perfect film coverage. Because of its self-limited growth mechanism, ALD can afford sub-nanometer thickness control. Precursors used in ALD should be volatile, thermally stable at the deposition temperature, and highly reactive towards the co-regent. Traditionally, ALD has been used to grow metal oxide films. However, the microelectronics industry now demands ALD for metals and metal nitrides. …