Chemistry Commons^™

Structure And Transport Characteristics Of Highly Rigid Ionomers, Lilin He

All Dissertations

The structure and transport characteristics in a novel family of ionomers consisting of a hydrophobic polyphenylene backbone substituted by sulfonic acid functionalized phenyl side chains (sPPs) have been investigated. These polymers have potential applications in electrochemistry as well as separation both as membranes and thin films. The bulk structure as a function of hydration has been explored by X-ray and neutron scattering. Interfacial structure was studied by AFM and neutron reflectometry. The characteristics of water in the bulk were studied by NMR and FTIR and that in thin films by neutron reflectometry.

The sPPs exhibit characteristic structure due to their …

Effects Of Polyphenol Compounds On Iron-And Copper-Mediated Dna Damage: Mechanisms And Predictive Models, Nathan Perron

All Dissertations

Polyphenol compounds are widely recognized for their antioxidant activity; however, under some conditions these compounds can also exhibit prooxidant activity. This work examined the interactions of polyphenols with iron and copper to improve understanding of both their antioxidant and prooxidant effects. Polyphenols with catechol and gallol groups effectively inhibit iron-mediated oxidative DNA damage by chelating iron, with IC₅₀ values ranging from 1-59 µM. Gallate compounds are more potent than their catecholate analogues in every instance, and their antioxidant potencies correlate to pK_a values for the most acidic phenolic hydrogen. This correlation represents the first predictive model of …

Exploratory Synthesis Of New Open-Framework Iron (Ii,Iii)-Containing Polyanion Systems Targeted For Lithium-Ion Battery Applications, Gregory Becht

All Dissertations

The chemistry demonstrated in this dissertation is concerned with the synthesis, structure, properties and applications of inorganic solids containing iron(II,II) redox centers. The endeavor in exploratory synthesis is due largely to the employment of molten salt fluxes such as alkali metal chloride. These halide-fluxes act in two parts; 1) as a solvent to lower the reaction temperature and 2) as an in situ source of unavailable alkali oxides through metathesis reactions. Using these halide fluxes has allowed for the discovery of several new transition metal-containing phosphates, arsenates, and vanadates for a structure/property correlation study. From this study the selected compounds …

Functionalized Carbon Nanotubes For Biological Applications, Lingrong Gu

All Dissertations

Carbon nanotubes with their unique pseudo-one-dimensional nanostructures and related electronic, optical, and mechanical properties have been attracting much attention for potential biological applications, such as biosensors, bio-delivery, bioimaging and so on. In this dissertation, recent studies and advances toward bioapplications of carbon nanotubes are critically reviewed, followed by detailed reports on my research projects concerning the use of carbon nanotubes as unique scaffolds for multivalent display of sugars and the relevant results from bio-evaluation of these novel nanomaterials.
Single-walled (SWNTs) and multiple-walled carbon nanotubes (MWNTs) were functionalized with amine-derivatived monosaccharides (galactoses and mannoses) and their dendritic constructs. These sugar-functionalized carbon …

Strategies For Expanding The Halogen Bonding Periodic Table And Desigining Complementary Halogen/Hydrogen Bonding Synthons, Hadi Arman

All Dissertations

Halogen bonding is the donation of electron density from an electron donor, such as N, O, S, Se atoms, to an electron acceptor such as a dihalogen or organohalogen. This interaction plays an important role in biological systems, such as the thyroid gland and is useful in many other fields such as drug design, crystal engineering, synthetic chemistry, material science and bioinorganic chemistry. However, currently there is a lack of information for this interaction in systems involving organoiodines with sulfur and selenium electron donors.
A variety of sulfur and selenium Lewis base donors were investigated with various organoiodines. The main …

Design And Validation Of A Multimethod Assessment Of Metacognition And Study Of The Effectiveness Of Metacognitive Interventions, Guillermo Sandi-Urena

All Dissertations

The central role of metacognition in learning and problem solving, in general and in chemistry in specific, has been substantially demonstrated and has raised pronounced interest in its study. However, the intrinsic difficulties associated with the inner processes of such a non-overt behavior have delayed the development of appropriate assessment instruments. The first research question addressed in this work originates from this observation: Is it possible to reliably assess metacognition use in chemistry problem solving? This study presents the development, validation, and application of a multimethod instrument for the assessment of metacognition use in chemistry problem solving. This multimethod is …

Synthesis And Pharmacology Of N-Alkyl-3-(Halo-Naphthoyl)Indoles, Valerie Smith

All Dissertations

The medicinal values of marijuana have often been overshadowed due to the psychotropic, 'recreational' effects it brings about in a user. For hundreds of years the therapeutic uses of cannabis sativa were appreciated, but the inability to control the dosage of the main constituent, and therefore the psychotropic effects, rendered the drug a liability. The elucidation of the structure of this main psychoactive constituent, ∆9-tetrahydrocannabinol (∆9-THC) by Gaoni and Mechoulam in 1964 opened the door to the discovery of a vast array of knowledge about cannabinoids. From the multiple classes of cannabinoids and the ways these compounds interact with the …

Electrochemical Synthesis And Characterization Of Polymers From Bis(3,4-Ethylenedioxythiophene)-Thiophenes (Bedot-Ts) And Bis(3,4-Ethylenedioxythiophene)-Benzenes (Bedot-Bs) As Optoelectronic Materials, Kalya Eaiprasertsak

All Dissertations

ABSTRACT


A series of bis(3,4-ethylenedioxythiophene)-thiophene derivatives (BEDOT-Ts) and bis(3,4-ethylenedioxythiophene)-benzene derivatives (BEDOT-Bs) monomers were electrochemically polymerized onto glassy carbon or ITO-coated glass electrodes. Cyclic voltammetry (CV), infrared (IR), UV-vis-NIR and photoluminescence (PL) spectroscopy were employed to investigate and characterize properties of resulting polymers. dc-conductivities of these polymers were measured by the four-point probe method.
Cyclic voltammetry studies show that the redox half potentials of PBEDOT-3BT, PBEDOT-3OT, PBEDOT-3TBS and PBEDOT-3MPT are -290, -297, -325 and -284 mV versus Ag/Ag+, respectively. The redox half potentials of PBEDOT-TOL, PBEDOT-BOB and PBEDOT-FB are -130, -147 and -327 mV vs. Ag/Ag+, respectively, and a bit higher …

Synthesis, Electronic Structure, And Reactivity Of Endohedral Metallofullerenes And Other Endohedral Carbon Nanostructures, Bevan Elliott

All Dissertations

The discovery in 1985 of fullerenes combined with the development of STM beginning in 1981 is credited as the starting point of the current nanoscience revolution. Endohedral fullerenes, discovered shortly after, have drastically different electronic properties when compared with the empty fullerenes. This dissertation has as its central focus the synthesis and electronic properties of endohedral metallofullerenes and other endohedral nanostructures.
The opening two chapters give a brief background of the discovery of fullerenes. A comprehensive literature list is given for the various families of trimetallic nitride endohedral fullerenes as well as other large endohedral metallic cluster fullerenes. Finally, a …

Beckmann Rearrangement Of Cyclotriveratrylene (Ctv) Oxime: Tandem Beckmann-Electrophilic Aromatic Addition, Marlon R. Lutz Jr., Matthias Zeller, Daniel P. Becker

Chemistry: Faculty Publications and Other Works

The Beckmann rearrangement has been performed on the oxime of cyclotriveratrylene (CTV) with thionyl chloride affording the ring-expanded 10-membered ring amide exclusively in high yield. Modified conditions afford a helical pentacycle derived from an unusual tandem Beckmann rearrangement and electrophilic aromatic addition followed by demethylation and tautomerization.

Becoming A Chemist: Graduate Students' Perspectives On Chemists And Chemistry, Bethany Walls

All Theses

In order to better understand the development of chemistry graduate students throughout the research phase of their Ph.D. degrees, we conducted a study on graduate students' self-concept of being chemists. This research is motivated by our previous results that forming identities as chemists is a key step in the transformation of organic chemistry graduate students from laboratory technicians into practicing chemists. In this research study, analytical, inorganic, and physical chemistry graduate students participated in a single, semi-structured interview designed to probe how their beliefs on what it means to know and practice chemistry affect their graduate training. Results from these …

Structure Of The Thioredoxin-Like Domain Of Yeast Glutaredoxin 3, Lydia M. Gibson, Nin N. Dingra, Caryn E. Outten, Lukasz Lebioda

Faculty Publications

Yeast glutaredoxin 3 (Grx3) is a cytosolic protein that regulates the activity of the iron-responsive transcriptional activator Aft1. This member of the monothiol glutaredoxin family contains a thioredoxin-like domain and a glutaredoxin-like domain, which both possess a monothiol active site. The crystal structure of the thioredoxin-like domain has been determined at 1.5 Å resolution and represents the first published structure of this domain for the monothiol glutaredoxin family. The loop containing the signature motif WAxxC is partially disordered, indicating a greater degree of flexibility in this region compared with classical dithiol thioredoxins with a WCGPC active-site motif.

I. Thermodynamics And Magnetism Of Cu2ocl2 Ii. Repairs To Microcalorimeter The "2"S Are Subscripts, And The Second 2 Is Preceded By A Lower Case L, Not A One, Thomas J. Parry

Theses and Dissertations

Adiabatic calorimetry provides accurate and precise specific heat (Cp) data. From this data, thermodynamic functions may be calculated. Cu2OCl2, melanothallite, became of interest as part of a study of a particular thermochemical cycle. The experimental specific heat data and the calculated thermodynamic functions are reported here. Free energies of formation, calculated from the thermodynamic functions, suggest the particular cycle of interest with this compound as an intermediate is not feasible; uncertainty as to the accuracy of CuO and CuCl2 data used in the calculations indicate further study may be necessary. Upon collection of the specific heat data, an antiferromagnetic transition …

Contraction-Expansion Protocols., Nadine Katia Njoya

Electronic Theses and Dissertations

An approach to a new class of compounds known as bridgehead dienone is described. The route is based on a tandem contraction-expansion event in which the contraction triggers the expansion. The two steps involved are a palladium-catalyzed Favorskii contraction and a cis-divinyl cyclopropanone rearrangement. Progress towards these goals is reported.

Synthesis Towards Fulminic Acid And Its Derivatives In 1, 3-Dipolar Cycloaddition Reactions., Ophilia Ndi Toh

Electronic Theses and Dissertations

A new approach to fulminic acid cycloadditions has been developed. At reduced temperatures, fulminic acid is generated in situ and undergoes 1, 3-diploar cycloaddition reactions with dipolarophiles to form isoxazolines and/or its dimers. This procedure represents a novel, safe general method for the one-step generation of fulminic acid, which complements existing potentially explosive protocols.

Monitoring Metal Containing Particulates Distribution On A College Campus Using Dandelion (Taraxacum Officinale) Leaves As Receptors., Suresh Chandra Regmi

Electronic Theses and Dissertations

This study aims to determine the distribution of particulates carrying heavy metals at selected sites on a college campus using dandelion leaves as collectors. As a comparison, sites far away from the campus surrounding Bristol Motor Speedway Car Racing Stadium were also monitored. To reduce the probability of memory effects from the long-term atmospheric deposition or absorption of metals from soil a seasonal plant, dandelion, was used to monitor the metal contents. The metals monitored are cadmium, calcium, copper, chromium, iron, lead, and zinc. Fourteen sites were monitored and samples were collected once a week initially (growing time of the …

Laboratory Studies Of Ice Formation Pathways From Ammonium Sulfate Particles, M. E. Wise, K. J. Baustian, M. A. Tolbert

CUP Faculty Research

Cirrus clouds are composed of ice particles and their formation pathways have been studied extensively in the laboratory. The ability of ammonium sulfate particles to act as nuclei for cirrus clouds has been of particular importance because of their ubiquitous presence in the upper troposphere. The results of past laboratory experiments of homogeneous ice nucleation from ammonium sulfate particles show a wide range of freezing conditions. In the present study, a flow tube apparatus equipped with Fourier transform infrared spectroscopy was used to resolve these discrepancies. It was found that when ammonium sulfate particles were preconditioned at 100% relative humidity …

A Radical Conjugate Addition Approach To The Total Synthesis Of Celogentin C, Steven G. Capps

Theses and Dissertations

The synthesis of five chiral DBFOX (dibenzofuran-oxazoline) ligands with either aryl or benzyl substituents will be presented. The requisite amino alcohols were obtained with high enantioselectivity either commercially (DBFOX/Bn), via Sharpless asymmetric aminohydroxylation (DBFOX/Nap, DBFOX/t-BuPh, DBFOX/Pip), or via phase-transfer catalyzed asymmetric alkylation (DBFOX/MeNap). These ligands, complexed with Mg(NTf2)2, were used as Lewis acid promoters of enantioselective radical conjugate additions to α/β-unsaturated nitro-amides/esters. A summary of these results is presented and discussed. These findings led us to believe that our initial binding model between metal, ligand, and substrate was flawed. Thus, we figured that if we started with a functionality known …

Heat Capacity And High Pressure Exploration Of Ybb2, Brant Abeln, Andrew Cornelius

Undergraduate Research Opportunities Program (UROP)

The compound YbB2 has been reported to order anti-ferromagnetically at temperatures around 5.6 K. This transition was verified from heat capacity data taken in different magnetic fields by our Quantum Design PPMS system. X-ray diffraction measurements have been performed using this sample under different pressures at the APS facility in Argonne National Laboratory. A sudden change in resistivity measurements of the sample indicated a possible structural phase transition around 3 GPa. The data indicates the YbB2 compound is not responsible for the anomaly.

Influence Of Nabh4 Reduction On The Hydrogen Storage Properties Of Aniline/Pd Composite Materials, Whitney Shofner, David W. Hatchett

Undergraduate Research Opportunities Program (UROP)

The characterization and chemical synthesis of composites containing aniline and N-Phenylenediamine (NPPD), synthesized with palladium, will be analyzed according to recent studies [1] to confer hydrogen storage capabilities. The palladium metal will be introduced as either PdCl4 2- or PdCl2 2-. The experiments will be carried out under both acidic and non-acidic conditions forming a total of 8 different compounds. Each compound will be reduced with NaBH4 and analyzed using gas chromatography to measure hydrogen storage. Infrared spectroscopy and ultraviolet visible spectroscopy will also be used to gather data concerning each compound.

Synthesis And Relaxometric Studies Of A Dendrimer‐Based Ph‐Responsive Mri Contrast Agent, M. Meser Ali, Mark Woods, Peter Caravan, Ana C.L. Opina, Marga Spiller, James C. Fettinger, A. Dean Sherry

Chemistry Faculty Publications and Presentations

The design of effective pH responsive MRI contrast agents is a key goal in the development of new diagnostic methods for conditions such as kidney disease and cancer. A key factor determining the effectiveness of an agent is the difference between the relaxivity of the “on” state compared to that of the “off” state. In this paper, we demonstrate that it is possible to improve the pH-responsive action of a low molecular weight agent by conjugating it to a macromolecular construct. The synthesis of a bifunctional pH responsive agent is reported. As part of that synthetic pathway we examine the …

Nanostructered Aminophenylporphyrin Films For Use In Bulk Heterojunction And Inverse Dye-Sensitized Tio₂ Solar Cells, Michael George Walter

Dissertations and Theses

Conductive nanostructured films of poly-tetrakis-5,10,15,20-(4-aminophenyl)porphyrin (TAPP) can be grown electrochemically or through interfacial oxidative polymerization. The poly-TAPP nanomorphology is sensitive to the electrochemical solvent, potentiometric method, and the aminophenyl porphyrin monomer utilized. To elucidate the molecular structure of poly-TAPP and to correlate structures with proposed polymerization and conductivity mechanisms, reflectance FT-IR and spectroelectrochemistry were used to detect the presence and electroactivity of dihydrophenazine and phenazine polymer linkages formed during the polymerization.

Poly-TAPP nanofiber films were evaluated for use in a bulk heterojunction solar cell (with PCBM) and in an inverse dye-sensitized TiO2 solar cell using the poly-TAPP nanoporous scaffold to …

Regulators Of G-Protein Signaling, Rgs13 And Rgs16, Are Associated With Cxcl12-Mediated Cd4+ T Cell Migration, Lijin Xia

Theses and Dissertations

Chemokines are important chemical signals that guide lymphocyte movement within the immune system and promote the organization and functions of germinal centers (GCs) in the secondary lymphoid tissues. Previous studies have shown that GC T cells exhibit high expression of chemokine receptor 4, CXCR4, but that these cells are unable to migrate to the ligand for this receptor, the chemokine CXCL12. This “migratory paralysis” to CXCL12 was found to be correlated with the expression of two Regulators of G-protein Signaling, RGS13 and RGS16 in the GC T cells. The objective of my research was to determine whether RGS13 and RGS16 …

Proposed Route To Cyclopenta[C]Thiophenes Via Activated Methylene, Vineet V. Karambelkar

Masters Theses & Specialist Projects

The synthesis of cyclopenta[c]thiophenes has been sparsely reported in the literature owing to several difficulties involved in their synthesis. The present work involves the proposed synthesis of cyclopenta[c]thiophenes and their precursors using activated methylene. Cyclopenta[c]thiophene compounds show promise in the field of polymer and catalysis chemistry. These substituted polythiophenes are potential organic semiconductors and anti-tumor agents. The research presented shows the successful and novel conversion of 3,4-bis(chloromethyl)-2,5-dimethylthiophene and 3,4-bis(bromomethyl)-2,5-dimethylthiophene to a fused 5,5'-fused membered ring which is the precursor to cyclopenta[c]thiophene the sulfone ester, 5-carbomethoxy-5- phenylsulfonyl-1,3-dimethyl-5,6-dihydro-4H-cyclopenta[c]thiophene, in just two steps as compared to four steps previously reported in the literature. …

A Selectivity Study On The Use Of Caffeine And Theobromine Imprinted Polypyrrole Surface Electrodes, Anil Kiran Kumar Vinjamuri

Masters Theses & Specialist Projects

Molecularly imprinted polymers (MIPs) are proving to be very effective in development of synthetic recognition systems and are of great interest to those interested in the field of sensor technology. The use of MIPs is receiving considerable interest due to the ability to prepare recognition matrices that possess high substrate selectivity and specificity. Conducting polymers (CP) have proved to be an excellent tool for the preparation of nano-structured biologically selective systems. Polypyrrole (Ppy) is one such CP that is extensively used for the construction of bioanalytical sensors. Ppy has shown great promise primarily due to its biocompatibility and thermal stability …

Admicelle-Based Solid Phase Extraction Of Phenols Using Dialkylammonium Surfactant In The Hydroxide Form, Kali R. Pickering

Masters Theses & Specialist Projects

A technique for admicelle-based solid phase extraction is presented in which a dialkylammonium surfactant in the hydroxide form is immobilized on silica. By converting dihexadecyldimethylammonium bromide to the hydroxide form, the surfactant is allowed to have the property of a strong base, aiding in the extraction of acidic phenols which are difficult to extract because of their differing polarities. The surfactant-silica admicelle parameters were optimized for the efficient extraction of eight phenols. Adsorbed phenols were eluted from the sorbent using small volumes of methanol. The phenols were preconcentrated from drinking water samples and were determined using high performance liquid chromatography …

Role Of Adenine In Thymine-Dimer Repair By Reduced Flavin-Adenine Dinucleotide, Guifeng Li, Vincent Sichula, Ksenija D. Glusac

Chemistry Faculty Publications

We present a study of excited-state behavior of reduced flavin cofactors using femtosecond optical transient absorption spectroscopy. The reduced flavin cofactors studied were in two protonation states: flavin-adenine dinucleotide (FADH(2) and FADH(-)) and flavin-mononucleotide (FMNH2 and FMNH-). We find that FMNH- exhibits multiexponential decay dynamics due to the presence of two bent conformers of the isoalloxazine ring. FMNH2 exhibits an additional fast deactivation component that is assigned to an iminol tautomer. Reduced flavin cofactors also exhibit a long-lived component that is attributed to the semiquinone and the hydrated electron that are produced in photoinduced electron transfer to the solvent. The …

Half-Metallicity In Hybrid Bcn Nanoribbons, Er-Jun Kan, Xiaojun Wu, Zenyu Li, Xiao Cheng Zeng, Jinlong Yang, J. G. Hou

Xiao Cheng Zeng Publications

The established chemical synthetic strategy toward graphene nanoribbons has greatly prompted and justified the research of theoretical designs of novel materials based on graphene. In this paper, we report the novel half-metallicity in C and BN hybrid zigzag nanoribbons even though stand-alone C or BN nanoribbon possesses a finite band gap. By performing first-principles electronic-structure calculations, we find this unexpected half-metallicity in the hybrid nanostructures stems from a competition between the charge and spin polarizations, as well as from the π orbital hybridization between C and BN. Molecular dynamics simulations indicate that the hybrid nanoribbons are stable. Our results point …

Mass Spectrometry-Based Biomolecular Recognition And Response Factor Investigations Using Electrospray Ionization, Misjudeen Raji

Chemistry & Biochemistry Dissertations - Archive

Integrins are transmembrane proteins found in almost all cells. They play vital roles in many biological processes, such as angiogenesis and signal transduction, through their interactions with different extracellular matrix ligands. These interactions are fostered by forming noncovalent bonds with the ligands. Integrin involvement in angiogenic cancer metastasis has sparked the interest of many researchers in the field of oncology. Many cutting edge research works are now focused on studying the noncovalent interactions of integrins with potential drug compounds formulated from peptide mimics and bearing the putative RGD amino acid sequence through which integrins are known to bind their ligands. …

Origin Of Size-Dependent Energy Transfer From Photoexcited Cdse Quantum Dots And Fluorescent Dyes To Gold Nanoparticles, Mariana Kondon

Masters Theses

The photoluminescence quenching of CdSe quantum dots (QD) and fluorescent dyes by hexanethiolate Mono layer Protected Clusters (MPCs) with core diameters of 1.1- 4 .9 nm is described.

The CdSe QD investigated had the following core diameters of 2.0, 2.6, 3.4 and 6.9 nm. The florescent dyes used were: Coumarin 440 (CM440), Fluorescein 548 (F548), Rhodamine 6G (R6G), Pyromethene 597 (PM597) and Lyssamine Dye (LD700). Experimental evidence suggests that the photoluminescence quenching of both CdSe QD and the fluorescent dyes occurs through energy transfer and that the AuMPCs are efficient quenchers in both cases. The larger MPCs are more efficient …