Chemistry Commons^™

Towards Carbon Dioxide Reduction: Synthesis And Characterization Of Ccc-Nhc Pincer Iron Complexes., Joshua Mensah

Theses and Dissertations

The industrial revolution came with its downside of emission of greenhouse gases into the atmosphere. The NOAA reported in 2019 that, of the greenhouse gases emitted into the atmosphere, CO2 contributed to about 80% of the increased greenhouse gases hence the need for CO2 Sequestering and Storage (CSS) and ultimately leading to Carbon Capture and Recycling (CCR) as a viable option to convert CO2 into useful forms. The race to find the best catalyst for CCR has led to the synthesis of many organometallic compounds. Pincer complexes catalyzed CO2 reduction has gained notoriety recently because of the tunability and robustness …

Exploring The Potentials Of Delafossite-Coated Cotton Textiles: Photocatalytic Self-Cleaning, Uv-Blocking, Anti Microbial Activity And Hydrophobicity, Shahria Ahmed

Theses and Dissertations

Delafossite materials demonstrate multifunctional applications due to their excellent catalytic properties, which vary depending on their morphology, particle size, and synthetic method. Herein, a few novel applications of the delafossites are reported, which can be implemented in commercial, medical, and domestic settings. In present work we are presenting two different delafossite CuGaO2 and CuFeO2 nanoparticles and its composite with cotton fiber. Multifunctional cotton fabric is prepared by depositing a uniform coating layer of CuGaO2 and CuFeO2, exhibits excellent photocatalytic self-cleaning, UV blocking, and antimicrobial activity. CuGaO2 and CuFeO2 nanoparticle concentrations of 1mM and 2mM were deposited over the cotton fabric …

Synthesis Of Nano-Microstructured Barium Titanate (Batio3) Incorporated In Pvdf-Hfp/Peo For Sustainable And Green Energy Generation, Rigobert Ybarra Jr.

Theses and Dissertations

The global reliance on fossil fuels and natural gas, has largely dominated the energy production field, but due to finite resource depletion and escalating greenhouse gas emissions, the immediate exploration of sustainable energy alternatives to mitigate climate change and ensure resource security has been a major concern. There has been extensive research into other more renewable methods of energy production such as wind and hydropower. Of these current energy generation types there are many areas of untapped potential from the mechanical movements generated ambiently not only in the large scale of power generation but also on a smaller scale. The …

Development Of Chiral Lewis Base Catalysts For Chlorosilane-Mediated Asymmetric C-C Bond Formations, Changgong Xu

Theses and Dissertations

The chiral hydrazine is a crucial structural motif that serves as pivotal structural elements in numerous natural products and biologically significant molecules. We are particularly interested in the catalytic asymmetric reduction of hydrazones, as well as the catalytic asymmetric propargylation and allenylation of hydrazones, because they provide direct pathways to these enantio-enriched chiral building blocks. In this work, we will explore the potential of two different categories of chiral Lewis base catalysts in the said transformations.

Developed by another student in our group, axial-chiral 3,3’-triazolyl biisoquinoline N,N’-dioxides derived catalysts are tested and demonstrated its capability in activating various hydrazone …

Modelling Terrestrial And Potential Extraterrestrial Photopigments Via Density Functional Theory, Dorothea Illner

Theses and Dissertations

In the search for extraterrestrial life, biosignatures play a crucial role in identifying its putative traces. A commonly known and robust biosignature is the Vegetation Red Edge (VRE), which can be described as a sharp increase of reflectance observed from a planet and stems from the light absorption of photopigments in specific regions in the electromagnetic spectrum. For Earth, this VRE is known to occur around 700 nm, however, if the photopigments absorb light in different regions and have different structures the VRE could experience a wavelenght shift.

In this work, Chlorophyll a and a potential photopigment precursor called Phot0 …

Electrocatalytic Degradation Of Bisphenol A Using Nickel Sulfide Supported On Graphene Oxide And Cobalt Sulfide Supported On Graphene Oxide Composite Materials, Katherine Ellynn Wright

Theses and Dissertations

The degradation of bisphenol A (BPA) by nickel sulfide supported on graphene oxide (NiS/GO) and cobalt sulfide supported on graphene oxide (CoS/GO) composite materials was investigated. The catalysts were studied to determine the optimal conditions for BPA degradation using electrocatalysis. Electrocatalytic trials were performed using varying parameters, which included electrolyte concentrations of 1.0 g/L, 2.0 g/L, and 4.0 g/L Na2SO4, pHs of 2, 4, and 6, and constant currents of either 0.100 A or 0.200 A. During the reaction samples were taken before the current was applied and 30 minutes and 60 minute intervals to observe the degradation of …

Studies Of Novel And Well-Defined Dinickel Architectures Utilizing An N-Atom Bridge, David Anthony De Los Santos

Theses and Dissertations

There has been a growing interest in organometallic chemistry to utilize late Earth-abundant metals towards challenging molecular functionalization of abundant feedstocks to value-added products. There is precedent of utilizing cooperativity to try and address some of the shortcomings of traditional mononuclear complexes by integrating metal-metal and or metal-ligand cooperativity to facilitate multi-electron transformations. The utility of a redox-noninnocent scaffold allows for the metal centers to be stable over a range of oxidation states, using the ligand to store electrons. Despite recent progress, complexes harnessing cooperative states towards challenging transformations is still an emerging field. Our group has synthesized a multinucleating …

Development Of Bifunctional Electrocatalyst For The Electrically Rechargeable Zinc Air Batteries, Thiruvenkatam S

Theses and Dissertations

The spontaneous reaction between zinc and oxygen in an alkaline medium is exploited in non-rechargeable aqueous zinc-air batteries (ZABs) to generate useful electricity. The primary ZAB has a rich history as it was used in tramways, railway signalling and it is being used in hearing aids, pacemakers, etc. The success of primary ZABs led to the development of two types of rechargeable ZAB, namely, mechanically rechargeable ZAB (mrZAB) and electrically rechargeable ZAB (erZAB). In mrZABs, the exhausted anode and electrolyte are replaced periodically. Whereas the chemistry of primary ZAB is reversed using suitable electrocatalysts in erZABs. Electrocatalysts used in erZABs …

The Study Of Biomass Based Polymers And Cyclic Polymers, Yishayah Bension

Theses and Dissertations

Plastics have become an integral part of everyday life, from household care to aerospace applications, polymers are involved in every industry. Most of these polymeric materials are derived from petroleum feedstocks which have deleterious effects on our environment. The production of petrochemicals has led to an increase in greenhouse gases and microplastic pollution which have accelerated climate change. My research focuses on utilizing existing biomasses to improve the plastic economy’s circularity. This work develops new materials from bio-based polymers such as lignin and soybean oil. Raw lignin suffers from inherently weak mechanical properties, poor solubility, processability, and molecular structure ambiguity. …

Advanced Oxidation Of Methyl Tert Butyl Ether With Ultraviolet Light Emitting Diodes, Aaron R. Neal

Theses and Dissertations

Methyl Tert-Butyl Ether (MTBE) is a volatile, soluble, organic compound introduced to gasoline within the United States as a fuel oxygenator in 1979. MTBE is a common groundwater pollutant due to its high water solubility and resistance to bio-degradation; it commonly infiltrates groundwater sources via leaking underground storage tanks or fuel spills. This research employed ultraviolet light emitting diodes (UV-LEDs) and hydrogen peroxide (H₂O₂) induced advanced oxidation process (AOP) to treat MTBE contaminated water at the bench scale. Using four H₂O₂:MTBE molar peroxide ratios (100:1, 200:1, 400:1, 500:1), MTBE degradation was induced …

Advanced Oxidation Of Tert-Butanol With Ultraviolet Light Emitting Diodes And Hydrogen Peroxide, Lauren R. Mainolfi

Theses and Dissertations

Tert-butanol (TBA), a versatile chemical widely used in industrial processes, poses exposure risks through inhalation, ingestion, and skin contact. Environmental contamination, often from industrial activities, emphasizes the importance of robust waste management and monitoring to protect water supplies from potential TBA migration and ensure drinking water safety. This study employed hydrogen peroxide (H2O2): TBA molar ratios of 100, 200, 400, and 500:1 in a Continuous Flow Stirred-Tank Reactor (CSTR) with UV-LED as the TBA degradation mechanism in an Advanced Oxidation Process (AOP). The UV-LEDs and H2O2 were synergistically employed to generate hydroxyl radicals in an advanced oxidation process. Gas chromatography–mass …

Development Of Salinomycin Derivatives As Potential Anticancer Agents, Viren Soni

Theses and Dissertations

Salinomycin is a poly-ionophore antibiotic that was originally isolated from Streptomyces albus by Miyazaki and colleagues from Kaken Chemicals Co., Ltd., Tokyo, Japan. Salinomycin exhibits antimicrobial activity against Gram-positive bacteria including Bacillus subtilis, Staphylococcus aureus, Micrococcus flavus, Sarcina lutea, Mycobacterium spp. Some filamentous fungi, Plasmodium falciparum, and Eimeria spp. as well as protozoan parasites responsible for the poultry disease coccidiosis. Hence, it is used in veterinary medicine. In 2009 Gupta et al demonstrated that salinomycin selectively killed human breast cancer stem cells (CSCs) with great efficacy, and the mechanism of action of this novel CSCs molecule was explored. To name …

Thin-Film Nanocomposite Membranes With Alumina Nanoparticles For Textile Wastewater Treatment Applications, Amr Mohamed Tayel

Theses and Dissertations

Thin-film nanocomposite (TFN) membranes are gaining great interest in industrial wastewater treatment due to their superior performance, especially for higher water flux and pollutants’ rejection, as well as improved chemical, thermal and mechanical stabilities, compared to other types of membranes. The performance of TFN membranes can be enhanced using different types of nanofillers, among which ceramic nanomaterials, such as Al2O3, offer a promising potential for applications involving treatment of industrial wastewater such as textile effluents, and this is due to their stability, hydrophilicity, and relative low cost. The study of the TFN membrane properties and structure allows the optimization and …

Analyzing Novel Metal Alloys For Glucose Sensing And Electrocatalysis, Anna Grace Boddy

Theses and Dissertations

In pharmaceutical and medicinal chemistry, metals and metal alloys often receive less attention compared to biological or organic compounds due to many factors including toxicity in the body for drug development or the cost of these metals. However, metals can play an important role in pharmaceuticals, having an impact on original cancer drugs, such as platinum used for head and neck tumors. Electrocatalysis is also another topic that receives less attention over topics such as chromatography in pharmaceuticals due to its potential toxic catalysts and voltages that could be harmful to the body. Electrocatalytic sensors can play an important role …

Synthesis And Characterization Of Bio Based Amphiphilic Molecules, Vandana Singh

Theses and Dissertations

Among various molecular self-assemblies, low molecular weight gelators (LMWGs), that can form gels in organic solvents/water/oils, have gained much research attention due to their huge potential applications. Generally, gels are soft nanomaterials formed by the self-assembly of amphiphilic molecules into a three-dimensional fibrous network entrapping the solvent.

As these gels are formed by self-assembly via non-covalent interactions they are reversible and differ from macromolecular gels. To synthesize LMWGs, biomolecules such as fats, oils, fatty acids, lignocelluloses, sugars, amino acids, and peptides are commonly used as their inherent property favors self-assembly. In the current scenario, interest in synthesizing bio-based gelators has …

A Qualitative Inquiry To The Impact Of Peer Teaching On Undergraduate Chemistry Students, Marcus Sambar

Theses and Dissertations

This study investigates the impact of peer teaching on undergraduate STEM majors, particularly those who serve as peer teachers for introductory chemistry courses. While previous research has predominantly focused on the benefits of peer tutoring for the tutored students, the reciprocal impact on peer teachers remains underexplored. The main purpose of this study is to quantify the differences between peer teachers and comparable students who do not engage in teaching, with a specific focus on problem-solving approaches and the ability to explain STEM concepts. The assessment included coding students' work to reveal strategy use and provide a means of comparison …

Photoluminescence Of Beryllium-Related Defects In Gallium Nitride, Mykhailo Vorobiov, Mykhailo Vorobiov

Theses and Dissertations

This study explores the potential of beryllium (Be) as an alternative dopant to magnesium (Mg) for achieving higher hole concentrations in gallium nitride (GaN). Despite Mg prominence as an acceptor in optoelectronic and high-power devices, its deep acceptor level at 0.22 eV above the valence band limits its effectiveness. By examining Be, this research aims to pave the way to overcoming these limitations and extend the findings to aluminum nitride and aluminum gallium nitride (AlGaN) alloy. Key contributions of this work include. i)Identification of three Be-related luminescence bands in GaN through photoluminescence spectroscopy, improving the understanding needed for further material …

Investigating The Ultrafast Dissociation Dynamics Of Energetic Materials Using Femtosecond Time-Resolved Mass Spectrometry, Jacob M. Shusterman

Theses and Dissertations

Shock initiation of energetic materials produces cations and anions that can contribute to initial endothermic chemical reactions which lead to detonation. Hence, knowledge of the initial dissociation pathways of ionized energetic molecules is important for advancing the understanding of initiation mechanisms and meeting longstanding goals of the Department of Defense. Despite their potential importance, these transient charged species are difficult to detect in detonation experiments and are often ignored in molecular dynamics modeling of shocked energetic materials. However, the technique of pump-probe femtosecond time-resolved mass spectrometry (FTRMS) paired with complementary theoretical calculations can be used to elucidate initial unimolecular dissociation …

Illuminating Function And Enabling Inhibition At The Protein-Membrane Interface Of Glutathione Peroxidase 4., Courtney L. Labrecque

Theses and Dissertations

Membrane proteins act as gateways to cells and are responsible not only for signaling, lipid transport, and cellular homeostasis, but they are also integral in disease pathologies. One class of membrane proteins, peripheral membrane proteins (PMPs), reside in aqueous compartments of the cell until they are recruited to the membrane to perform their function. Glutathione peroxidase 4 (GPx4) is a PMP enzyme responsible for engaging the membrane and reducing lipid hydroperoxides, thereby preventing cellular death via ferroptosis. Due to its central function surrounding ferroptosis, GPx4 is an interesting drug target that has recently gained interest for inflammatory diseases as well …

Elucidation Of The Optical Properties Of Si And Si-Ge Alloy Nanostructures With Visible To Near-Ir Photoluminescence, Griffin Spence

Theses and Dissertations

Silicon and silicon-germanium alloy nanostructures have garnered increasing attention in the past 25 years due to their favorable optical properties, visible to near-IR luminescence, and inherently low toxicity. While many synthetic routes have been discussed in the literature, the high-temperature, solid-state disproportionation of hydrogen silsesquioxane (HSQ) has become the most popular way to produce highly crystalline, size-tunable Si and Si-based nanostructures (NCs). It has been shown in this work that maximum annealing temperature from 450°-1100°C and the addition of GeI₂or SnCl₄ precursors can be used to achieve different morphologies, alloying efficiency, and sizes. Directly annealing HSQ from …

Effect Of Annealing On Photoluminescence From Defects In Gan, Oleksandr Andrieiev

Theses and Dissertations

Annealing is a critical process in modern GaN technology, essential for achieving p-type conductivity by activating the Mg_Ga acceptor, as first demonstrated by Shuji Nakamura in the early 1990s. Despite the omnipresence of hydrogen as an impurity in GaN crystals, the precise mechanisms governing hydrogen diffusion and acceptor passivation remain only partially understood. The presented research investigates the effects of annealing-induced activation and hydrogen passivation on C and Be acceptors in GaN grown by MOCVD, HVPE, and MBE methods. We explored these effects by using several annealing techniques, gas compositions, and thermal regimes. A transient behavior between the C …

Measuring The Properties Of Rod-Shaped Bacteria By Single-Entity Electrochemistry, Ashley Tubbs

Theses and Dissertations

Antibiotic-resistant bacteria pose a significant and escalating threat to hospitals around the world, necessitating the development of rapid and sensitive detection methods. Single-entity electrochemistry has emerged as a promising approach for detecting and identifying such bacteria, and monitoring the efficacy of antibiotics in real-time. Herein, we employ the translational diffusion equation for circular cylinders to predict the collision frequency of rod-shaped bacteria, informing our experimental setup. Our work demonstrates that lab-fabricated Pt ultramicroelectrodes can sensitively detect bacteria at femtomolar concentrations under migration-controlled conditions. Further, we present a method implemented in MatLab to automate the analysis of step-like signals observed in …

Asymmetric Cuh-Catalyzed Reductive Coupling Of Allenamides With Carbonyl And Imine Electrophiles, Stephen Collins

Theses and Dissertations

The carbon scaffold of many drugs and natural products contain multiple stereogenic centers bearing heteroatoms. As a result of this, chemists have long sought methods to efficiently install these multi-heteroatom functionalities. Reductive coupling reactions have been extensively studied over the past decades, and the allylation of carbonyls via the reductive coupling approach has been a key method for generating chiral allylic alcohols. This work utilizes inexpensive Cu for the asymmetric reductive coupling of allenamides with carbonyls or imines to simultaneously install two heteroatoms (either oxygen and nitrogen or nitrogen and nitrogen, respectively) onto the product. These molecules have a polarity …

Synthesis And Characterization Of Porphyrin And Phthalocyanine-Based Photosensitizers For Energy And Biomedical Applications, Mavis Forson

Theses and Dissertations

Porphyrins have been widely used as photosensitizers in research due to their important role in many biological processes. Phthalocyanines have also gained interest in biological applications such as photodynamic therapy (PDT). This dissertation is focused on the synthesis of different photosensitizers for various applications. This dissertation's first section focuses on research involving synthesizing covalently bonded donor-acceptor systems as photosensitizers. Specifically in this work, two porphyrin-fullerene dyads were synthesized using a modified tetraphenyl porphyrin with varying bridges between the porphyrin and fullerene. Metal was incorporated in the porphyrin core to enhance the properties of the dyads as photosensitizers. Detailed photophysical properties, …

High Temperature Materials From Bis-Ortho-Diynylarene (Boda)-Derived Resins And Perfluorocyclobutyl (Pfcb) Aryl Ether Polymers, Ernesto Isaac Borrego

Theses and Dissertations

This work expands the current understanding of materials chemistry and engineering capabilities of two synthetic platforms: 1.) bis-ortho-diynylarenes (BODA) and 2.) trifluorovinylaryl ethers (TFVE). Each platform possesses a unique chemistry which paradoxically enables the development of high-performance materials therefrom while simultaneously retaining exceptional melt and solution processability. Leveraging the apparent dichotomy in properties (performance/processability) obtainable from these two synthetics platforms, we have pursued and achieved a practical approach to high-temperature resistant materials with an immense potential for technology transfer and commercialization:

1.) BODA-derived resins (BDR) constitute a versatile platform of melt-processable resins capable of rapidly producing high performance …

Investigating The Magnetic And Electronic Properties Of Cobalt(Ii) Heteroscorpionate Isomers, Jamie Dawn Freeman

Theses and Dissertations

Cobalt(II) scorpionates possess distinct electronic and magnetic properties in comparison to other first-row transition metal complexes in this ligand class. One unique property is their significantly downfield paramagnetically shifted 11B NMR signals. The utilization of a heteroscorpionate ligand Tp’ introduces asymmetry to metal scorpionates, producing cis and trans isomers. cis- and trans-Co(Tp’)2 were synthesized and separated by column chromatography. 11B NMR data show cobalt(II) homoscorpionates resonances in a narrow 20 ppm shift range around 270 ppm while cis- and trans-Co(Tp’)2 differ with signals at 230 ppm and 140 ppm, respectively. Paramagnetic NMR studies indicate both isomers maintain the same spin …

Uniquely Tailored Ionic Materials For Implementation In Energy, Imagining, And Antibacterial Applications, Amanda Jalihal

Theses and Dissertations

In this dissertation, the novel class of ionic materials is explored. Ionic materials are easily tuned and tailored to fit a wide variety of applications. The synthesis of ionic materials is extremely simple and prompt. Briefly, two ionic moieties are joined electrostatically through a double displacement resulting in a new compound without complicated synthesis. This process leads to a close proximity of the ions which allows for enhancement of the FRET mechanism between a fluorophore and chromophore. A potential application of a FRET active ionic material is explored as a photosensitizer using IR820 and Nile Blue A. The ionic material, …

Thin Film Piezoelectric Energy Harvesting Nanostructured Materials: Tailoring Size, Porosity, Morphology Of Zinc Stannate Perovskites (Abx3), Christopher Munoz

Theses and Dissertations

Three dimensional (3D) piezoelectric zinc stannate (ZnSnO3) nanoweb arrays are synthesized using a combination of treatment methods deposited in PDMS thin films for electrochemical analysis of its piezoelectric response. Advantages of hydrothermal, molten salt, and solvothermal synthesis methods were leveraged to facilitate several chemical and surface engineering techniques. The combination of these treatments reduce the size of zinc stannate to approximately ~40nm-80nm weblike networks, much smaller than previously reported ZnSnO3 sub-micro cubes. Scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) analysis reveal a mesoporous protonated tristannate (H2Sn3O7) nanoweb template with connecting wirelike strands having diameters ranging from 12-27nm across and …

Electrolysis Degradation Of Cyanuric Acid In Wastewater At Cu/Go Cathodes, Chioma Chinwe Nwakanobi

Theses and Dissertations

This work evaluates the development of electrochemical processes for the oxidative degradation of persistent organic chemicals in waste waters, specifically the oxidation of cyanuric acid in the presence of NaCl at Cu/GO cathodes and Ti anodes. The experiment used a graphene oxide doped copper mesh cathode to examine different concentrations of cyanuric acid (30 mg/L, 40 mg/L, and 50 mg/L) and various concentrations of NaCl electrolyte (0.007mol/L, 0.03mol/L, 0.07mol/L, 0.1mol/L, and 0.2mol/L). In addition, the effect of pH (2, 4, 6, and 8), and applied current (0.200A, 0.150A and 0.100A) were studied. The Cu/GO electrode played a central role in …

Chemical Investigation Of Dichloromethane Extract Of Aloe Vera Peels: An Agricultural Waste, Nazmul Huda

Theses and Dissertations

Aloe barbadensis Miller, commonly called Aloe Vera, is a widely popular succulent plant species cultivated across subtropical regions worldwide from India to the Tex-Mex border. Besides its historical uses, Aloe juice has garnered attention as a potential remedy for various ailments, particularly in treating various skin conditions and facilitating wound recovery, including obesity, diabetes, hepatitis, Crohn's disease, and ulcerative colitis. Regrettably, the agricultural practice following sap extraction involves discarding Aloe vera peels, constituting agricultural waste. As part of our continuous research on extraction, isolation, separation, and spectral characterization of value-added chemicals present in waste botanicals herein, …