Chemistry Commons^™

Electrospun Ethyl Cellulose Nanofibers With Phase Change Materials: Designing Temperature-Responsive Drug Delivery Systems, Michael Wildy

Theses and Dissertations

In this study, ethyl cellulose (EC) nanofibers loaded with either Rhodamine B (RhB) or Doxorubicin HCl (DOX) and phase change materials (PCM) were fabricated by blend electrospinning. EC is a cellulose derivative widely used as an excipient in the pharmaceutical industry and an ideal polymer for controlled drug release. Lauric acid (LA) and stearic acid (SA) were used as a material with a melting point close to physiological body temperature. Good drug-polymer compatibility and an amorphous distribution of drugs were shown by Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction. The release rate of RhB was shown to …

Dynamic Regulation Of Store-Operated Calcium Entry By Protein S-Acylation, Goutham Kodakandla

Theses and Dissertations

Calcium plays a pivotal role in many physiological functions in cells. Cytosolic calcium levels are finely tuned by calcium ion channels, pumps, and intracellular organelles. Store-operated calcium entry (SOCE) is when depletion of endoplasmic reticulum (ER) calcium stores activates a calcium sensor known as stromal interaction molecule 1 (STIM1). Activation of STIM1 leads to a conformational change from a compact state to an extended state. This extended state of STIM1 allows it to bind to a calcium channel in the plasma membrane (PM) known as Orai1. The binding of Orai1 and STIM1 leads to opening of Orai1 channels and calcium …

Structural Design And Synthesis Of Growth Factor Receptor Binding Protein 2 (Grb2) Stabilizing Small Molecule, Mahfuzul Hasan

Theses and Dissertations

The growth factor receptor tyrosine kinase (RTK) family is a potent inducer of cellular growth. Ligand binding to cognate receptors on plasma membrane induces receptor dimerization and activation, which in turn recruits intracellular molecules for downstream signal transduction. A key signaling pathway activated by growth factor (GF) receptors is the Ras signaling cascade that ultimately leads to cell proliferation. Activation of RTKs leads to the recruitment of adapter protein Grb2, which is constitutively bound to the mammalian homolog of drosophila son of sevenless (SOS), and a guanine exchange factor (GEF) for Ras. The recruitment of the Grb2-SOS complex by activated …

Reactive Molecular Dynamics Of Large Systems: Quantum Dynamics With Adaptable Gaussian Bases; Hydroxide Diffusion In A Polymeric Environment, Mohottige Sachith Prasanga Wickramasinghe

Theses and Dissertations

This dissertation describes our research in theory and applications of reactive molecular dynamics. Quantum dynamics provides the foundation for understanding chemical processes. However, the computational cost of describing a general quantum system scales exponentially with the system size. Thus, an efficient basis representation of wavefunctions is essential. Time-dependent Gaussian bases are often employed to describe the large-amplitude motion of high-dimensional systems. The time dependence of such bases is typically determined by (i) the variational principle or by (ii) classical dynamics. But those approaches have shortcomings due to intrinsic singularity of the variational equations in the full basis limit or due …

Investigation, Synthesis And Rational Design Of Novel Transuranic Containing Extended Structures, Adrian Thomas Hines

Theses and Dissertations

The use of nuclear technology has proven useful for energy generation and for weapons manufacturing, but disposal and storage of nuclear waste is an ongoing problem. The accumulation of nuclear waste over the past decades has yielded a vast amount of waste that must be dealt with, and with space at interim storage facilities diminishing, it has become increasingly important to find solutions to nuclear waste storage. The vitrification process has been widely accepted as a viable route for immobilization of high-level waste; however, the process is inadequate for complex waste streams and has many drawbacks such as limited waste …

Antimicrobial Polymers And Small Molecules From Multicyclic Compounds And Engineering Of Sustainable Polymers, Leman Buzoglu Kurnaz

Theses and Dissertations

In this dissertation, the synthesis of polymers and small molecules from multicyclic compounds and the development of sustainable polymers from renewable feedstock were investigated. The antimicrobial biomaterials and sustainable polymers were characterized and their properties were discussed. In Chapter 1, the overall background and recent developments of antimicrobial biomaterials and their application were discussed. Later, sustainable polymers from renewable biomass and their synthesis methods were given. Afterward, the main research objectives of this doctoral research study were described. In Chapter 2, the synthesis of multiple charged small molecules from multicyclic compounds was discussed. These compounds were obtained by using various …

Exploring The Assembly Of Soluble Triphenylamine Bis-Urea Macrocycles; Synthesis Of Nsc243928 Derivatives For Triple-Negative Breast Cancer Treatment, Rahul Prakash

Theses and Dissertations

This dissertation is divided into two topics: I. Supramolecular polymerization of triphenylamine (TPA) bis-urea macrocycle behavior in solution, and II. Synthesis of fluorophore appended and biotinylated derivatives of NSC243928 for the treatment of triple-negative breast cancer. Supramolecular polymers are of interest due to their self-healing and stimuli responsiveness. Chapter 1 gives a brief overview of the importance of self-assembly to construct ordered structures from smaller building blocks, highlighting the mechanisms of self-assembly to form supramolecular polymers. The bis-urea macrocycle assembly unit is introduced and its assembly into tubular structures and crystals is highlighted, which are used as a control for …

Structural, Functional And Biochemical Studies To Elucidate The Molecular Basis Of Xenobiotic Metabolism Of Tetranychus Uritcae, A Major Agricultural Pest, Ricardo Hernandez Arriaza

Theses and Dissertations

The two-spotted spider mite, Tetranychus urticae, is a major cosmopolitan pest that feeds on more than 1,100 plant species, including 150 crops. Such a wide host range indicates this mite’s unparalleled xenobiotic responsiveness that is also coincident with their ability to rapidly develop resistance to pesticides. An unprecedently large detoxifying machinery is one of the main biological traits responsible for their extraordinary adaptation potential and devastating effect on crops. Availability of the whole genome sequence revealed expansions in all major detoxifying families and demonstrated that this genome has been enriched by horizontally transferred genes from bacteria and fungi. Motivated by …

Interfacial Ligand Transformation On Plasmonic Nanostructures: Mechanistic Insights Unraveled By Plasmon-Enhanced Spectroscopy, Kexun Chen

Theses and Dissertations

We employ surface-enhanced Raman scattering (SERS) as an in situ spectroscopic tool, in conjunction with density functional theory (DFT) calculations, to develop a detailed mechanistic understanding of plasmon-driven photocatalytic reactions and heterogeneous transfer hydrogenolysis reactions of molecular adsorbates on metallic nanostructure surfaces. The excitation and decay of plasmon resonances in metallic nanostructures give rise to intriguing photophysical and photochemical effects, including the generation of hot charge carriers, local field enhancements, and photothermal transduction. These effects can be intentionally harnessed to drive or enhance interfacial molecular transformations along unconventional reaction pathways. The first part of the thesis focuses on the plasmon-driven …

A Work Towards A Single-Bridge Hydrazine Sensor, Brenden Jay Schmeltz

Theses and Dissertations

Hydrazine can currently be detected by irreversible methods, Carbazolopyridinophane (2,18-Dithia[3][1,8]carbazolo[3][2,6]pyridinophane) CP was synthesized by Brown et al. to detect hydrazine in real-time while also being reversible. The threshold for detection was 100 ppb, regulatory use requires 10 ppb as this is when permanent damage to humans can be caused. A more sensitive sensor will allow for safer workplaces for many people. A single, 3-atom bridge sensor will further examine the photophysical capabilities of carbazole-pyridine as an emitter/quencher pair. 1-Carbazole-1-methylpyridyl-2methyl sulfide SBCP will allow freedom of rotation as well as the bending of the bridge. These benefits will introduce conformers which …

Fundamental Study Of Ionic Liquid Physicochemical Effects On Thermal Stability Of Model Biological Macromolecules, Austin Keith Clark

Theses and Dissertations

Ionic Liquids (ILs) are substances with a unique physical attribute compared to that of solid ionic salts. At room temperature, ILs are molten salts that have a variety of physical effects that can play a role in their impact on other molecules, as solvents or solutes. They can play the role of the solvent in a variety of applications, from biofuels to organic catalysis or as excipients in pharmaceutical formulations. These ILs have a desirable use as solvents due to their ability to be tunable substances. Changing the cation or anion of the IL causes a change in its physical …

Mechanistic Investigations Of A Novel Braf Regulatory Switch And Braftide, An Allosteric Peptide Inhibitor Of Braf, Alison Yu

Theses and Dissertations

RAF kinases (ARAF/BRAF/CRAF or Raf-1) are serine/threonine kinases in the MAPK (RAS-RAF-MEK-ERK) pathway. The MAPK pathway is crucial in development and normal cell function. These same roles are dysregulated in cancer; BRAF is the most frequently mutated isoform in cancers and in particular, activation loop mutants BRAF V600E/K mutants have the highest mutational incidence. Three FDA approved inhibitors potently inhibit BRAF V600E/K mutants. However, these same inhibitors fail to address the non-V600E/K mutations and result in paradoxical activation of the MAPK pathway. Two strategies were employed to address the limitations of the FDA-approved inhibitors: provide novel regulatory details of RAF …

Investigations On Copper Assisted Oxidative Transformations For The Construction Of Diverse C-C/C-N(O) Bonds, Prasanna Kumari S

Theses and Dissertations

Copper catalyzed C-C, C-N/C-O bond formation reactions are a prominent tool to access diverse biologically relevant molecules. Herein, we present the copper- catalyzed diverse C-C/C-N(O) bond forming reactions. In Chapter-I (introduction), we briefly discussed the various copper mediated organic transformations with appropriate examples.

In Chapter II, we report a one-pot methodology for the vicinal aminoalkylation of naphthoquinone through a direct C(sp2)-H functionalization reaction. Through this method, readily available planar naphthoquinone substrates were transformed into three-dimensional molecular scaffolds through the formation of one C(sp2)-C(sp2) and two C(sp2)-N bonds. The indole fused nitrogen heterocyclic products were obtained in good yields. Apart from …

The Synthesis And Optimization Of Conductive Carbons From Renewable Resources For Supercapacitor Applications, Iris Denmark

Theses and Dissertations

The use of fossil fuels has played a pivotal role in the evolution of energy storage devices and the generation of electricity. With that, we have now entered an era in which we have become primarily dependent on these non-renewable resources which have become increasingly scarce overtime. This has driven us toward a pertinent demand for alternative sources of energy. There are various forms of alternative energy in which biomass is the most used. Carbon is becoming the most commonly used material for energy applications due to its versatility and bioavailability, including that which is sourced from biomass. Herein is …

Synthesis And Characterization Of Redox-Noninnocent Pyrazine(Diimine) Iron Complexes And An Inverted Pyridine(Diimine) Ligand, Jaylan Billups

Theses and Dissertations

Cooperativity between the metal center and the ligand has been shown in nature to be an important feature of systems that catalyze two-electron processes that first-row transition metals usually cannot catalyze on their own. In these cases, the ligand acts as a site of reactivity that in many instances can store electrons or react directly with substrates in solution. The design and study of systems where there is synergy between the metal and the ligand have been leveraged to catalyze polymerization and hydrogenation-type reactions as well as the activation of small molecules such as dihydrogen. Specifically, the pyridine(diimine) ligand scaffold …

Identifying Student Challenges In Organic Chemistry: Supporting Student Understanding Through Eye-Tracking, Think-Aloud Interviews And Alternative Questions, Lisa Ann Smith

Theses and Dissertations

Think-aloud interviews are a strategy used to identify misconceptions held by students. We incorporated think-aloud interviews and studied representational competence of novice and expert participants with identifying alkyl halides with multiple representations. We hypothesized that the participants would approach representations differently and think-aloud interviews would reveal misconceptions. Eye-tracking results showed that novice and expert participants differ in their approaches to representations and that novice participants spend more time on representations. Think-aloud interviews revealed that novice participants contain misconceptions on alkyl halide identification. This research provided insights on student understanding in identifying alkyl halides and representations, allowing instructors to use student …

Transition Metal-Catalyzed Functionalization Of Carbon-Hydrogen Bonds In Alkenes, Xiaolin Qian

Theses and Dissertations

Alkenes can undergo a variety of chemical reactions to form more complex molecules with a range of functional groups. This makes them useful starting materials for synthesizing a wide range of organic compounds. Chapter I provided an overview of the development history of alkenyl C−H bond activation. The early reactions of C−H compounds with metal complexes, as well as stoichiometric activation of the transition metal-activated C–H bond, were discussed. Then the first successful and efficient organometallic-catalyzed transformations of a C−H bond, the first transition metal-catalyzed vinylic C–H functionalization, and the first transition metal-catalyzed olefinic C–H functionalization under mild conditions were …

Fabrication And Imaging Of Highly Ordered Plasmonic Au Nano-Prism And Self-Assembled Supramolecular Nanostructure, Ridwan Tobi Ayinla

Theses and Dissertations

The precise control of the resonance frequency of plasmonic nanostructures is critical and depends on the size, composition, shape, and dielectric nature of the environment. The ability to control the shape and size of nanomaterials acutely depends on the fabrication technique and material design. We used a cheap and scalable method known as nanosphere lithography (NSL) to fabricate plasmonic nano-prism (NP) on glass and indium tin oxide substrate (ITO). The methods involve substrate hydrophilicity treatment, polystyrene nanosphere masking, metal deposition, and mask removal. The array and specific morphology of the fabricated NP was established using scanning electron microscope (SEM) and …

Improved Stoichiometric Synthesis Of Ccc-Nhc Pincer Rh Complexes And Catalytic Activity Towards Dehydrogenative Silylation And Hydrosilylation Of Alkenes, Enock Amoateng

Theses and Dissertations

N-Heterocyclic carbenes (NHCs) have attracted growing interest not only as successful ancillary ligands in a wide variety of transition-metal-catalyzed reactions but have also shown to offer photophysical and electrochemical properties. The metalation/transmetalation strategy using [Zr(NMe₂)₄] as initial metalating reagent offers an efficient approach to the preparation of CCC-NHC pincer complexes of the late transition metals such as Rh and Ir. In the process of investigating an intermediate and the mechanism of the metalation/transmetalation to Rh sequence, a mixed valent bimetallic CCC-NHC pincer Rh complex with two chloro ligands bridged between a [(CCC-NHC)Rh(III)] and a [Rh(I)(COD)] fragment …

Indium Doped Zinc Stannate-Pdms Based Piezoelectric Generator For Harvesting Mechanical Energy And Sensory Application, Tamanna Zakia

Theses and Dissertations

Piezoelectric materials are comparatively new among other alternative energy sources. Harvesting waste mechanical energy through these materials can be a potential solution of the increasing energy demand. In response to applied mechanical stress, piezoelectric materials accumulate electric charges on their surface. Upon connecting with a circuit, accumulated charges can flow and generate electricity. Based on this hypothesis piezoelectric nano-generator has been fabricated. Binary semiconducting oxides such as ZnO, TiO2 and SnO2 have attracted immense interest as they have unique properties of electron mobility. However, there is always a need for specially designed semiconductors to better match with the properties. This …

Organocatalyzed Four-Component On-Water Green Synthesis Of Spiroindolinpyranopyrazole, Tanzida Zubair

Theses and Dissertations

Although many synthetic and natural pharmaceuticals and drug-like compounds contain spiro center(s) in their structures, the synthesis of spiro centers is seen to be an exciting and difficult area of research. The synthesis of spiro compounds and their derivatives was carried out using a four-component process that included reagents like hydrazine hydrate, isatin, malononitrile, and an active methylene compound like ethyl acetoacetate. Microwave irradiation was used in a short time range (5 – 30 min) and moderate temperature (80°C), with water as a solvent, and N, N-Diisopropylethylamine (DIPEA) as a catalyst to give high yield of products. Our process complies …

Manufacturing Of A Flexible Piezoelectric Nanogenerator By Functionalizing Polyvinylidene Fluoride With Lithium Tantalate And Multiwalled Carbon Nanotubes For Energy Harvesting And Sensing Applications, Islam Uddin Shipu

Theses and Dissertations

Mechanical energy is one of the readily accessible green energy sources that could be employed to meet the small-scale energy requirement. In order to capture mechanical energy, power the next generation of electronic gadgets, and health monitoring flexible piezoelectric nanogenerators made of light weight polymers and carbon nanotubes have drawn a lot of attention. Lithium tantalate (LiTaO3), a ferroelectric substance, was prepared here and utilized to create a flexible piezoelectric nanogenerator (FPNG). A compact piezoelectric nanogenerator that successfully transfers mechanical energy into electricity was then created using lightweight polyvinylidene fluoride (PVDF), multi-walled carbon nanotube (MWCNT), and LiTaO3 nanoparticles. To create …

From Waste To Energy: The Electrochemical Reduction Of Co2 Using Recycled Nanostructured Catalysts, Ibrahim Badawy

Theses and Dissertations

The reduction of carbon dioxide (CO₂RR) using electrochemistry is a promising solution for the burgeoning global energy crisis. The overall vision of its implementation relies on renewable energy sources to power the reaction creating carbon neutral products and effectively closing the carbon cycle. Research in this field has come a long way since its inception in the mid-1900s. However, there remain significant hurdles and important considerations to overcome in order to reach full commercialization. Most electrocatalysts tested for CO₂RR have been designed solely for maximum performance while ignoring the environmental consequences if such a material were …

The Synthesis Of Novel Rare Earth Thiosilicates Using The Boron Chalcogen Mixture Method For An Interest In Their Magnetic And Optical Properties, Adam Alexander King

Theses and Dissertations

The chalcogens or the group sixteen elements excluding oxygen, are of interest due to their wide variety of structures and compositions, which gives the potential for a plethora of desired physical properties. This is due to their increased ability to catenate, forming stable chalcogen-chalcogen bonds. When the chalcogens combine with certain main group elements and transition metals they form anionic framework building blocks known as chalcometallates. One such chalcometallate of interest is the thiosilicates, compounds containing Si-S bonds as the anionic frameworks. These compounds are of interest due to their potentials in both their optical and magnetic properties. However, traditional …

Study Of Digital Algan Alloy Based Heterostructures Using Aln/Gan Short Period Superlattice, Mohammad Kamal Hussain

Theses and Dissertations

Ultrawide Bandgap (UWBG) and Extreme Bandgap (EBG) AlxGa1-xN (x > 0.40) alloys with EG > 4.2 eV are potential candidates for high temperature and high voltage applications, compared to Wide Bandgap (WBG) GaN-based lateral channel devices. Since critical electric field (Ec) scales as (Eg)^2.5, theoretically AlGaN alloys can sustain large electric field before breaking down. However, achieving linear ohmic contacts to the 2-dimensional electron gas (2DEG) formed at the interface of AlyGa_1-xN/ Al_xGa_1-xN (y – x ≥ 0.20) High Electron Mobility Transistors (HEMTs) is challenging. Direct contact through the AlGaN barrier is difficult due …

Dissolved Oxygen Dynamics And Nutrient Cycling In Marine And Lacustrine Benthic Communities, Corrianna R. Boucher

Theses and Dissertations

The delivery of biodetritus to the sediment water interface supports a complex series of biogeochemical reactions collectively referred to as early diagenesis. From the abyssal ocean to littoral freshwater ecosystems, this work explores the dynamics of these reactions in deep ocean detrital aggregates and lacustrine benthic algal mats. In the ocean, periods of increased export flux to abyssal depths increase the organic carbon export as aggregates to the seafloor while in littoral freshwater, proliferations of benthic algae such as Microseira wollei have grown to fill much of the shallow water column they inhabit.

Data collected at Station M (Sta. M) …

Computational Studies Of Bond Dissociation Energies And Organic Reaction Mechanisms, Shehani Thishakkya Wetthasinghe

Theses and Dissertations

This dissertation presents the progress of two independent projects. Chapter 2 and Chapter 3 focus on the first project, which involves material exploration utilizing machine learning techniques. We explore the potential use of cobaltocenium (CoCp⁺₂) derivatives as metal cations in anion exchange membranes (AEMs) for alkaline fuel cells, highlighting their superior thermal and alkaline stability compared to ammonium derivatives. The stability of CoCp⁺₂ can be fine-tuned by varying the substituent groups attached to the cyclopentadienyl ring (Cp) in CoCp⁺₂ .These derivatives encompass a variety of electron-donating and electron-withdrawing groups as substituents on both …

Identification Of New Disinfection Byproducts In Drinking Water And Impacts Of Algae, Md. Tareq Aziz

Theses and Dissertations

The disinfection of water has been hailed as one of the most important triumphs for public health in the 20th century. Drinking water treatment plants produce safe drinking water by inactivating microorganisms through the use of disinfectants, including chlorine, chloramine, chlorine dioxide, UV irradiation, and ozone. However, these disinfectants also produce toxic disinfection by-products (DBPs), through reactions with natural organic matter and anthropogenic pollutants, as well as bromide and iodide present in source waters. The presence of bromide and iodide results in the formation of bromo- and iodo-DBPs which are much more toxic than DBPs containing chlorine. DBPs are always …

Study Of Non-Covalent Interactions Using Molecular Rotors And Balances, Daniel Onyekachi Madukwe

Theses and Dissertations

The main focus of this dissertation is on the quantification of non-covalent interactions using molecular rotors and balances. While molecular rotors were used to measure kinetic effects of weak non-covalent interactions, molecular balances were used to measure their thermodynamic effects. Chapters 1 and 2 focus on the use of molecular rotors in measuring and studying the kinetic effects of the hydrogen bonding interaction on the bond rotation transition states. Chapters 3 and 4 focus on the quantification of lone pair – lone pair and sp²-CH/π interactions respectively, using molecular balances. These studies were carried out in the …

Expanding On The Solid State Chemistry Of F-Element Chalcogenides, Logan Skyler Breton

Theses and Dissertations

An overarching goal in solid state chemistry is to achieve predictability regarding the synthesis of compounds with desired properties. While this goal is far from being reached, solid state chemists are hard at work synthesizing and characterizing new materials to further our understanding of structure-property relationships, and to expand our fundamental knowledge to rationalize the outcomes of solid-state syntheses. With the advent of new solid state synthetic methods, novel compounds exhibiting exciting properties are still being discovered today. The infancy of these synthetic methods promises a myriad of undiscovered compounds with potentially interesting properties which has resulted in a recent …