Chemistry Commons^™

Design And Synthesis Of Novel Agrofungicides Based On Naturally Occurring Pbdes, Robert Alexander Smith

Electronic Theses and Dissertations

Cyanobacterial symbionts of Indo Pacific marine sponges, e.g. Dysidea sp., produce hydroxylated (OH-) polybrominated diphenyl ethers (PDBEs) which likely function as chemical deterrents owing to their antifungal and antibacterial properties. Limiting the therapeutic potential and agricultural use of these antimicrobial natural products are the negative connotations associated with non hydroxylated anthropogenic PBDEs. Anthropogenic PBDEs are pervasive global pollutants used as flame retardant additives in many household goods, e.g. furniture, textiles, and electronics. These molecules have a propensity to bioaccumulate in living organisms, they easily traverse the trophic food chains, they are readily passed from mother to offspring, and many of …

Investigations On Morphology, Spectroscopy And Near-Infrared Photoresponse Sensitization Of Conjugated Polymers In Organic Photovoltaics, Zhongjian Hu

Electronic Theses and Dissertations

Conjugated polymer architecture and morphology are two of the key factors that determine corresponding opto-electronic device performance. It is well-known that conjugated polymers display a variety of conformations and exhibit aggregation in their materials and even for individual polymer chains. The intrinsic structural heterogeneity of conjugated polymers strongly complicates the active layer morphology and phase separation, which are crucial for photoinduced charge generation and transport in polymer based bulk heterojunction-organic photovoltaics device (BHJ-OPVs). Aiming to probe the molecular level correlations between conjugated polymer architecture, morphology and optoelectronic properties, single molecule spectroscopy (SMS) and single particle spectroscopy (SPS) were employed. The …

The Application Of Chemometrics To The Detection And Classification Of Ignitable Liquids In Fire Debris Using The Total Ion Spectrum, Jennifer N. Lewis

Electronic Theses and Dissertations

Current methods in ignitable liquid identification and classification from fire debris rely on pattern recognition of ignitable liquids in total ion chromatograms, extracted ion profiles, and target compound comparisons, as described in American Standards for Testing and Materials E1618-10. The total ion spectra method takes advantage of the reproducibility among sample spectra from the same American Society for Testing and Materials class. It is a method that is independent of the chromatographic conditions that affect retention times of target compounds, thus aiding in the use of computer-based library searching techniques. The total ion spectrum was obtained by summing the ion …

Characterization Of Composite Broad Band Absorbing Conjugated Polymer Nanoparticles Using Steady-State, Time-Resolve And Single Particle Spectroscopy, Maxwell Scotland Bonner

Electronic Theses and Dissertations

As the global economy searches for reliable, inexpensive and environmentally friendly renewable energy resources, energy conservation by means of photovoltaics has seen near exponential growth in the last decade. Compared to state-of-the-art inorganic solar cells, organic photovoltaics (OPVs) composed of conjugated polymers are particularly interesting because of their processability, flexibility and the potential for large area devices at a reduced fabrication cost. It has been extensively documented that the interchain and intrachain interactions of conjugated polymers complicate the fundamental understanding of the optical and electronic properties in the solid-state (i.e. thin film active layer). These interactions are highly dependent on …

Ion Transport, Viscoelastic, And Thermal Properties Of Several Poly(Ethylene Glycol) And Poly(Propylene Glycol) Based Polymer Electrolytes, Benjamin Jacob Yancey

Electronic Theses and Dissertations

This dissertation explores the relationship between ionic conductivity, viscosity, and thermal properties of several MePEG and MePPG based copolymer electrolytes. In particular two main copolymer modifications have been investigated namely copolymerization with "bulky groups" and cross polymerization of MePEG and MePPG monomers. The modifications were made to vary the fractional free volume of the MePEG polymers. All of the copolymers obeyed the Doolittle equation. For both the bulky copolymers and MePEG/MePPG copolymers, increases in the FFV corresponded to increases in the viscosity and decreases in FFV correspond to decreases in viscosity. The FFV and H+ conductivity for these copolymers were …

Theoretical Characterization Of Non-Covalent Weakly Bound Clusters Through The Application Of Sophisticated Computational Quantum Chemistry Methodologies And The Development Of Integrated Fragmentation Techniques, Desiree Bates

Electronic Theses and Dissertations

Non-covalent, weakly bound clusters have been and remain of significant interest to many researchers. However, with computational studies, accurate description of these interactions requires sophisticated electronic structure methods employing large basis sets. This methodology becomes extremely computationally demanding as the size of the system increases. This work presents benchmark data and explores methods for obtaining highly accurate ab initio results for larger systems at greatly reduced computational costs. CCSD(T) complete basis set limit interaction energies are presented for a variety of parallel-slipped π...π dimers and low-lying isomers of (h₂o)₆. The calibration of a 2-body:Many-body fragmentation method …

Characterization Of Intermolecular Pi-Type Interactions Using Sophisticated Quantum Mechanical, Electronic Structure Computations, Emily Joy Carrell

Electronic Theses and Dissertations

Much like the instrumentation in an experimental lab, computational chemists use computers to solve the mathematical equations that describe the physics of electrons to understand the chemistry involved. The combination of the two main components of computational chemistry, the basis set and method, determines the ``cost'' (disk, memory, and CPU time) of a computation. A variety of basis sets and methods have been developed in the past century. The focus of this report is to accurately describe non-covalent interactions with the use of various quantum computational techniques. In Chapter 1 a brief discussion on the theory behind computational chemistry is …

Two-Photon Cross Section Enhancement Of Photochromic Compounds For Use In 3d Optical Data Storage, Gheorghe Luchita

Electronic Theses and Dissertations

Rewritable photochrome-based 3D optical data storage requires photochromic molecules with high two-photon absorption (2PA) cross sections. Currently, the low value of two-photon absorption cross sections of existing photochromes makes them unsuitable for practical application in 3D data storage. Worldwide attempts to increase the cross section of photochromic molecules by altering the chemical structure have yielded poor results. In this work, two ways to increase the two-photon absorption cross sections of photochromes were investigated. In the first method, partial success demonstrated by extending the conjugation of a photochromic molecule, a high two-photon absorption cross section of the closed form isomer and …

Self-Assembly And Photophysics Of Selected Organic Materials And Two-Photon Bioimaging With Profluorescent Nitroxides, Polyelectrolyte Nanoparticles, And Squaraine Probes, Hyo Yang Ahn

Electronic Theses and Dissertations

Two-photon absorption and upconverted fluorescence has been utilized in a variety of applications in pure science and engineering. Multiphoton-based techniques were used in this research in order to understand photophysical and chemical characteristics of several fluorescent dyes and to demonstrate some of their key applications. Two-photon fluorescence microscopy (2PFM) has become a powerful technique in bio-photonics for non-invasive imaging in the near-infrared (NIR) region (700~1000 nm) that often results in less photobleaching. In Chapter 1, there is a brief introduction to fluorescence, examples of fluorescence materials, and a discussion of the advantages of two-photon absorption. 2PFM imaging was utilized in …

Investigation Of Nanoceria-Modified Platinum-Gold Composite Electrodes For The Electrochemical Reduction Of Oxygen In Alkaline Media, Rahul Hegishte

Electronic Theses and Dissertations

Platinum-gold and nanoceria-modified platinum-gold electrodes were prepared on a platinum surface via electrochemical reduction of solutions of platinum and gold salts in the dispersion of nanoceria. The molar ratios of Pt and Au were varied in both PtAu and PtAu/CeO₂ electrodes while the total concentration of the metals was maintained at 2 x 10⁻³M and the concentration of nanoceria was maintained constant at 5 x 10⁻³M. The electrodes were characterized by their cyclic voltammetry curves in 0.5M sulfuric acid solution. The electrochemically active area of the electrodes was determined using the copper underpotential deposition method. The linear sweep voltammograms of …

The Application Of Two-Photon Absorbing Probes In Lysosomal, Zinc Ion Sensing And Folate Receptor-Targeted Bioimaging, Xuhua Wang

Electronic Theses and Dissertations

Two-photon fluorescence microscopy (2PFM) has become a powerful technique for bioimaging in non-invasive cancer diagnosis and also investigating the mechanization and original of a variety of diseases by tracking various biological processes. Because the fluorescence emission by two photon absorbing (2PA) is directly proportional to the square of the intensity of excitation light, this intrinsic property of 2PA provides 2PFM great advantages over traditional one-photon fluorescence microscopy (1PFM), including high 3D spatial localization, less photodamage and interference from biological tissue because of using longer wavelength excitation (700-1300 nm). However, most 2PA probes are hydrophobic and their photostabilities are questionable, severely …

The Relative Recoverability Of Dna And Rna Profiles From Forensically Relevant Body Fluid Stains, Charly Parker

Electronic Theses and Dissertations

Biological material (fluids or tissues) whether from the victim or suspect is often collected as forensic evidence, and methods to obtain and analyze the DNA found in that material have been well established. The type of body fluid (i.e. blood, saliva, semen, vaginal secretions, and menstrual blood) from which the DNA originated is also of interest, and messenger RNA typing provides a specific and sensitive means of body fluid identification. In order for mRNA profiling to be utilized in routine forensic casework, RNA of sufficient quantity and quality must be obtained from biological fluid stains and the methods used for …

The Study Of Three Different Layered Structures As Model Systems For Hydrogen Storage Materials, Muzaffer Tonguç Öztek

Electronic Theses and Dissertations

The strength and success of the hydrogen economy relies heavily on the storage of hydrogen. Storage systems in which hydrogen is sequestered in a solid material have been shown to be advantageous over storage of hydrogen as a liquid or compressed gas. Many different types of materials have been investigated, yet the desired capacity and uptake/release characteristics required for implementation have not been reached. In this work, porphyrin aggregates were investigated as a new type of material for hydrogen storage. The building blocks of the aggregates are porphyrin molecules that are planar and can assume a face to face arrangement …

Conjugate Additions And Transposition Of The Allylic Alcohols Of Enol Ethers Of 1, 2-Cyclohexanedione., Barnabas Otoo

Electronic Theses and Dissertations

A variety of protected enolic forms of 1, 2-cyclohexanedione was prepared as substrates for conjugate addition studies using organocopper reagents. The sequence involved the enol ether preparation via the enolate, alkylation with an organometalic reagent, and oxidative rearrangement with pyridinium chlorochromate followed by the conjugate addition reactions. Protection of 1, 2-cyclohexanedione was achieved by reacting with chloro tert-butyldimethyl silane and subjected to alkylation. Steric problems were encountered and so an alternative protective group the methoxymethyl acetal was prepared and studied. Alkylation of these derivatives was successful; however, the oxidation was problematic and although evidence for rearrangement was observed in one …

The Correlation Of The Concentration Of Selected Metals Determined In Water And Fish Samples From A Public Pond., Paula Kay Edwards

Electronic Theses and Dissertations

The concentrations of heavy metals (Cd, Cu, Fe, Ni, Pb, Zn) were measured in water, and fish samples caught from the pond at Fishery Park in Unicoi County, TN. The water samples were collected once a week for 8 weeks. The amounts of metals in the muscle tissues, gill, and liver of the two fish species were measured. This was to determine if any correlation exists between the metal contents in water and those in the fish samples. The concentration ranges for the heavy metals found in the water samples are as follows: Zn 0.04-0.13; Cu, 0.00-0.00; Pb, 0.00-0.59; Cd, …

Cyanoscorpionates And Transition Metal Complexes., Donald Martin Johnson

Electronic Theses and Dissertations

The new dihydrobis(4-cyano-3-tert-butylpyrazolylborate) ligand has been synthesized. Isolated crystals of the thallium complex were collected and structurally characterized by X-ray diffraction. Transition metal complexes of the ligand are currently under investigation.

Assessing Commercial Organic And Conventionally Grown Vegetables By Monitoring Selected Heavy Metals Found In Them., Charles Kafui Dotse

Electronic Theses and Dissertations

Commercially available organic and conventionally grown vegetables were studied by quantitative determination of selected metals in them and to determine if any differences found are statistically significant. These findings can help the consumers to determine if the vegetable products are within the recommended maximum limits as proposed by the joint FAO/WHO Expert committee on organic foods designation. Eight edible vegetables were purchased from local stores in both the organic and conventionally grown categories. Samples were digested with concentrated nitric acid and the metals monitored were zinc, copper, lead, iron, cadmium, and nickel using flame atomic absorption. The concentration range for …

Novel Photochemical Methodologies For Diversity Oriented Synthesis And Screening Of Combinatorial Libraries, Roman Askatovich Valiulin

Electronic Theses and Dissertations

The main goal of this project was to develop an efficient methodology allowing rapid access to structurally diverse scaffolds decorated with various functional groups.

Initially, we discovered and subsequently developed an experimentally straightforward, high-yielding photoinduced conversion of readily accessible diverse starting materials into polycyclic aldehydes and their (hemi)acetals decorated by various pendants. The two step sequence, involving the Diels-Alder addition of heterocyclic chalcones and other benzoyl ethylenes to a variety of dienes, followed by the Paternò-Büchi reaction, was described as an alkene-carbonyl oxametathesis. This methodology offers a rapid increase in molecular complexity and diversity of the target scaffolds.

To develop …

Physicochemical And Thermochemical Properties Of Sulfonated Poly(Etheretherketone) Electrolyte Membranes, Stephen Rhoden

Electronic Theses and Dissertations

Fuel cells have long been seen as an alternative to combustion powered and diesel powered engines and turbines. Production of energy via a fuel cell conversion method can generate up to 60% efficiency in comparison to 30% using a combustion powered engine, with low co-production of harmful side-products. The polymer electrolyte membrane (PEM) adapted for the fuel cell application is one of the main components that determines the overall efficiency. This research project was focused towards novel PEMs, such as sulfonated poly(etheretherketone) or SPEEK, which are cost-efficient and robust with high proton conductivities under hydrated conditions. The degree of sulfonation …

Mechanistic Importance Of Redox Potentials And Conformational Flexibility In Electron-Transferring Flavoproteins, Michael Anthony Swanson

Electronic Theses and Dissertations

The mitochondrial matrix flavoproteins electron transfer flavoprotein (ETF) and electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) are responsible for linking fatty acid β-oxidation with the main mitochondrial respiratory chain. Electrons derived from flavoprotein dehydrogenases are transferred sequentially through ETF and ETF-QO to ubiquinone and then into the respiratory chain via complex III. In this study, the effects of changes in ETF-QO redox potentials on its activity and the conformational flexibility of ETF were investigated.

ETF-QO contains one [4Fe-4S]^2+,1+ and one flavin adenine dinucleotide (FAD). In the porcine protein, threonine 367 is hydrogen bonded to N1 and O2 of the flavin ring …

Statistical Analysis Of Visible Absorption Spectra And Mass Spectra Obtained From Dyed Textile Fibers, Katie Margaret White

Electronic Theses and Dissertations

The National Academy of Sciences recently published a report which calls for improvements to the field of forensic science. Their report criticized many forensic disciplines for failure to establish rigorously-tested methods of comparison, and encouraged more research in these areas to establish limitations and assess error rates. This study applies chemometric and statistical methods to current and developing analytical techniques in fiber analysis. In addition to analysis of commercially available dyed textile fibers, two pairs of dyes are selected based for custom fabric dyeing on the similarities of their absorbance spectra and dye molecular structures. Visible absorption spectra for all …

Particle Matter Measurements For Inspection/Maintenance Programs, Daniel Joseph Pope

Electronic Theses and Dissertations

Particle emissions from Heavy Duty Diesel Vehicles (HDDVs) are currently measured by opacity or dynamometer gravimetric analysis. The Electronic Tailpipe Particle Sensor (ETaPS) is an inexpensive measurement device purported to give real time response to particle mass and was proposed as a possible addition to Inspection/Maintenance (I/M) programs. There were three goals to this study. The first was to verify ETaPS response to particle mass of HDDV exhaust. Integrated ETaPS signal was plotted against filter weight from dynamometer gravimetric analysis and a correlation was found. The second goal was to find a correlation between ETaPS readings and the Remote Sensing …

Determining The Presence Of An Ignitable Liquid Residue In Fire Debris Samples Utilizing Target Factor Analysis, Kelly Mchugh

Electronic Theses and Dissertations

Current fire debris analysis procedure involves using the chromatographic patterns of total ion chromatograms, extracted ion chromatograms, and target compound analysis to identify an ignitable liquid according to the American Society for Testing and Materials (ASTM) E 1618 standard method. Classifying the ignitable liquid is accomplished by a visual comparison of chromatographic data obtained from any extracted ignitable liquid residue in the debris to the chromatograms of ignitable liquids in a database, i.e. by visual pattern recognition. Pattern recognition proves time consuming and introduces potential for human error. One particularly difficult aspect of fire debris analysis is recognizing an ignitable …

Black Writing Ink Analysis By Direct Infusion Electrospray Mass Spectroscopy, Christopher M. Moody

Electronic Theses and Dissertations

An optimized method of extraction, an instrumental analysis method and data analysis was proposed for black writing inks based on direct infusion electrospray-mass spectrometry (ESI-MS). The sampling and analysis method is both minimally destructive and able to assess differences in inks from a reference collection of thirty ballpoint, gel, and rollerball inks. The methanol extracts of ink on paper samples were analyzed with three direct infusion (ESI-MS) methods. Each method varied scan voltage negative and positive, ESI fragmentor applied voltage (+120V, +0V, and -120V), and mobile phase additive. Direct infusion ESI-MS analysis, followed by pair-wise comparisons of the observed ion …

Approaches Towards The Synthesis Of Bradyoxetin, Vanildo Martins Lima Braga

Electronic Theses and Dissertations

Quorum sensing bacteria produce and release chemical signal molecules (like N-acyl homoserine lactones, AHL) that increase in concentration as a function of cell density. The responses cover a large spectrum of process such as the virulence in Staphylococcus aureus, competence for DNA-uptake in Bacillus subtilis and Streptococcus pneumoniae, sporulation in Bacillus subtilis, conjugal plasmid transfer in Enterococcus faecalis, and bacteriocin production in lactic acid bacteria. The collapse of (AHL) signaling system in bacteria represents an attractive therapeutic approach towards the development of new antibiotics. Recently, a new extracellular modulator was isolated from a symbiotic bacterium (Bradyrhizobium japonicum) that nodulates soybean. …

Polarization Dependent Two-Photon Absorption Properties Of Chiral Molecules, Carlos Toro

Electronic Theses and Dissertations

Molecules that are non-superimposable on their mirror image are named chiral or optically active compound. Over the years, molecular chirality has played an essential role in the understanding of fundamental aspects associated the origin of life, drug and food technologies and, asymmetric catalysis, among others. Moreover, most of the groundbreaking discoveries and advances made in this field have happened due to the development of spectroscopic techniques based on the natural asymmetry of the enantiomers and their ability to preferentially absorb right or left polarized light. For instance, circular dichroism (CD), which measures the difference in absorption between these two states …

Novel Improvements On The Analytical Chemistry Of Polycyclic Aromatic Hydrocarbons And Their Metabolites, Wang Huiyong

Electronic Theses and Dissertations

Polycyclic aromatic hydrocarbons (PAH) are important environmental pollutants originating from a wide variety of natural and anthropogenic sources. Because many of them are highly suspect as etiological agents in human cancer, chemical analysis of PAH is of great environmental and toxicological importance. Current methodology for PAH follows the classical pattern of sample preparation and chromatographic analysis. Sample preparation preconcentrates PAH, simplifies matrix composition, and facilitates analytical resolution in the chromatographic column. Among the several approaches that exist to pre-concentrate PAH from water samples, the Environmental Protection Agency (EPA) recommends the use of solid-phase extraction (SPE). High-performance liquid chromatography (HPLC) and …

Laboratory Studies To Field Evaluation : Remediation Of Polychlorinated Biphenyl Contaminated Painted Surfaces Through The Use Of Activated Metal Treatment Systems, Erin Kristen Saitta

Electronic Theses and Dissertations

Polychlorinated Biphenyls (PCBs) are a group of 209 congeners that are regulated under the Toxic Substance Control Act. They enter the environment as a result of industrial processes and can travel long distances. PCBs are environmentally persistent and bioaccumulate in animal populations. Painted surfaces are a common point source for PCBs and there are few options for remediating structures painted with PCB-contaminated paint. Removal of the paint can often spread contamination and disposing or burning of large structures is expensive. Experiments employing reductive dehalogenation through the use of a bimetal have shown that PCBs can be degraded in mild laboratory …

The Fabrication Of Polymer-Derived Sicn/Sibcn Ceramic Nanostructures And Investigation Of Their Structure-Property Relationship, Sourangsu Sarkar

Electronic Theses and Dissertations

Polymer-derived Ceramics (PDCs) represent a unique class of high-temperature stable materials synthesized directly by the thermal decomposition of polymers. This research first focuses on the fabrication of high temperature stable siliconcarbonitride (SiCN) fibers by electrospinning for ceramic matrix composite (CMC) applications. Ceraset™ VL20, a commercially available liquid cyclosilazane, was functionalized with aluminum sec-butoxide in order to be electrospinnable. The surface morphology of the electrospun fibers was investigated using the fibers produced from solvents. The electrospun fibers produced from the chloroform/N,N-dimethylformamide solutions had hierarchical structures that led to superhydrophobic surfaces. A “dry skin” model was proposed to explain the formation of …

Fabrication Of Functional Nanostructures Using Polyelectrolyte Nanocomposites And Reduced Graphene Oxide Assemblies, Anindarupa Chunder

Electronic Theses and Dissertations

A wide variety of nanomaterials ranging from polymer assemblies to organic and inorganic nanostructures (particles, wires, rods etc) have been actively pursued in recent years for various applications. The synthesis route of these nanomaterials had been driven through two fundamental approaches - 'Top down' and 'Bottom up'. The key aspect of their application remained in the ability to make the nanomaterials suitable for targeted location by manipulating their structure and functionalizing with active target groups. Functional nanomaterials like polyelectrolyte based multilayered thin films, nanofibres and graphene based composite materials are highlighted in the current research. Multilayer thin films were fabricated …