Chemistry Commons^™

Towards The Total Synthesis Of (+/-)-Gephyrotoxin 287c, Maciej E. Domaradzki

Dissertations, Theses, and Capstone Projects

Studies directed toward the total synthesis of (+/-)-Gephyrotoxin 287C are described herein. Even though the target alkaloid has been synthesized four times to date, it still presents an interesting synthetic challenge. Our ultimate goal is to develop an efficient enantioselective synthetic route utilizing oxazolone chemistry in order to demonstrate its utility as a dienophilic component in intramolecular Diels-Alder reactions. This is part of a greater ongoing study aimed at a range of suitable alkaloid targets.

Chapter 1 provides introduction to frog toxins as secondary metabolites and subsequently shifts to the target alkaloid. (+/-)-Gephyrotoxin 287C was originally described by Daly and …

Aesthetics In Action: Arts In A Democratic Society: Les Aspin Center For Government, Curtis L. Carter

Chemistry Faculty Research and Publications

No abstract provided.

Synthetic Approaches To The Understanding Of Dna Nucleobase Methylation, Jagruti Rana

Dissertations

DNA methylation is a major source of genetic variation and cancer. Methylation occurs when nucleophilic DNA bases react with methylating agent methyl methanesulfonate (MMS), dimethyl sulfate (DMS), N-methyl-N-nitrosourea (MNU), N-methyl-N-nitro-N-nitrosoguanidine (MNNG), etc. N7-methyl-2'-deoxyguanosine (N7-methyl-dG, or ^7MedG) adduct is the most abundant DNA methylation products for most methylating agents. DNA polymerase actions on ^7MedG are difficult to study due to its instability against ring- opening hydrolysis and deglycosyl ati on. Oligonucleotides containing a single chemical adduct of ^7MedG cannot be chemically synthesized. In addition, ^7MedG is unstable in vivo …

Synthesis And Characterization Of Polymer (Sulfonated Poly-Ether-Ether-Ketone) Based Nanocomposite (H-Boron Nitride) Membrane For Hydrogen Storage, R. Muthu Nareth, S. Rajashabla, Ramaiyan Navaneetha Kannan

All Physics Faculty Publications

The development of light weight and compact hydrogen storage materials is still prerequisite to fuel-cell technology to be fully competitive. The present experimental study reports the hydrogen storage capability of sulfonated poly-ether-ether-ketone (SPEEK)-hexagonal boron nitride (h-BN) (SPEEK-h-BN) nanocomposite membranes. The nanocomposite membranes are prepared by considering various amount of h-BN (0, 1, 3 and 5 wt. %) by phase inversion technique. The degree of sulfonation of the PEEK (SPEEK) is found to be 65% by Proton Nuclear Magnetic Resonance (¹H NMR) spectroscopy. Hydrogen adsorption studies have been carried out using a Seiverts-like hydrogenation setup. The membranes are characterized …

Synthesis Of Dinucleoside Acylphosphonites By Phosphonodiamidite Chemistry And Investigation Of Phosphorus Epimerization, William H. Hersh

Publications and Research

The reaction of the diamidite, (iPr2N)2PH, with acyl chlorides proceeds with the loss of HCl to give the corresponding acyl diamidites, RC(O)P(N(iPr)2)2 (R = Me (7), Ph (9)), without the intervention of sodium to give a phosphorus anion. The structure of 9 was confirmed by single-crystal X-ray diffraction. The coupling of the diamidites 7 and 9 with 5′-O-DMTr-thymidine was carried out with N-methylimidazolium triflate as the activator to give the monoamidites 3′-O-(P(N(iPr)2)C(O)R)-5′-O-DMTr-thymidine, and further coupling with 3′-O-(tert-butyldimethylsilyl)thymidine was carried out with activation by pyridinium trifluoroacetate/Nmethylimidazole. The new dinucleoside acylphosphonites could be further oxidized, hydrolyzed to the H-phosphonates, and sulfurized to …

Building And Testing Correlations For The Estimation Of One-Electron Reduction Potentials Of A Diverse Set Of Organic Molecules, Dalvin D. Méndez-Hernández, Jason G. Gillmore, Luis A. Montano, Devens Gust, Thomas A. Moore, Ana L. Moore, Vladimiro Mujica

Faculty Publications

We describe and evaluate a method for computationally predicting reduction potentials of a diverse group of organic molecules by linearly correlating calculated lowest unoccupied molecular orbital energies with ground state reduction potentials measured in acetonitrile. The approach is shown to provide a unique combination of extreme computational simplicity and excellent accuracy across a diverse range of organic structures and a wide window of reduction potentials. A disparate set of molecules (74 compounds belonging to six distinct structural families, comprised of molecules containing C, H, N, O, F, Cl, and Br, with functional groups including esters, ketones, halides, nitriles, quinones, alkenes, …

Homologous Recombination, Regulation, And Breast Cancer Emergence, Elliot Corless

Research on Capitol Hill

No abstract provided.

Gold(I)-Catalysed Synthesis Of Cyclic Sulfamidates: Current Scope, Stereochemistry And Competing Ene-Allene Cycloisomerisation, Mari C.M. Higginbotham, Lorna Kennedy, Anita G. Lindsay, Andreas Troester, Magnus Bebbington

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

Six-membered cyclic sulfamidates are prepared in high yields by treatment of allenic sulfamates with readily available Ph3PAuNTf2. The reaction enables formation of N-substituted quaternary centres in high yields. The relative stereochemistry has been unambiguously determined. A π-rearrangement is faster than hydroamination in the case of an allyl-substituted sulfamate and a mechanism is proposed for this process.

Characterization Of Biomass Burning Emissions From Cooking Fires, Peat, Crop Residue, And Other Fuels With High-Resolution Proton-Transfer-Reaction Time-Of-Flight Mass Spectrometry, C. Stockwell, P. Veres, J. Williams

Chemistry and Biochemistry Faculty Publications

We deployed a high-resolution proton-transferreaction time-of-flight mass spectrometer (PTR-TOF-MS) to measure biomass-burning emissions from peat, crop residue, cooking fires, and many other fire types during the fourth Fire Lab at Missoula Experiment (FLAME-4) laboratory campaign. A combination of gas standard calibrations and composition sensitive, mass-dependent calibration curves was applied to quantify gas-phase non-methane organic compounds (NMOCs) observed in the complex mixture of fire emissions. We used several approaches to assign the best identities to most major “exact masses”, including many high molecular mass species. Using these methods, approximately 80–96% of the total NMOC mass detected by the PTR-TOFMS and Fourier …

Hidden Formaldehyde In E-Cigarette Aerosols, R. Paul Jensen, Wentai Luo, James F. Pankow, Robert M. Strongin, David H. Peyton

Chemistry Faculty Publications and Presentations

This letter reports a chemical analysis of vapor from electronic cigarettes that shows high levels of formaldehyde, a known carcinogen. The authors project that the associated incremental lifetime risk of cancer could be higher than that from long-term smoking.

Repressive Mutations Restore Function-Loss Caused By The Disruption Of Trimerization In Escherichia Coli Multidrug Transporter Acrb, Zhaoshuai Wang, Meng Zhong, Wei Lu, Qian Chai, Yinan Wei

Chemistry Faculty Publications

AcrAB-TolC and their homologs are major multidrug efflux systems in Gram-negative bacteria. The inner membrane component AcrB functions as a trimer. Replacement of Pro223 by Gly in AcrB decreases the trimer stability and drastically reduces the drug efflux activity. The goal of this study is to identify suppressor mutations that restore function to mutant AcrB_P223G and explore the mechanism of function recovery. Two methods were used to introduce random mutations into the plasmid of AcrB_P223G. Mutants with elevated drug efflux activity were identified, purified, and characterized to examine their expression level, trimer stability, interaction with AcrA, and …

Observations And Analysis Of Organic Aerosol Evolution In Some Prescribed Fire Smoke Plumes, A. A. May, T. Lee, G. R. Mcmeeking, Sheryl Kashi Akagi, A. P. Sullivan, S. P. Urbanski, Robert Yokelson, S. M. Kreidenweis

Chemistry and Biochemistry Faculty Publications

Open biomass burning is a significant source of primary air pollutants such as particulate matter and non-methane organic gases. However, the physical and chemical atmospheric processing of these emissions during transport is poorly understood. Atmospheric 5 transformations of biomass burning emissions have been investigated in environmental chambers, but there have been limited opportunities to investigate these transformations in the atmosphere. In this study, we deployed a suite of real-time instrumentation on a Twin Otter aircraft to sample smoke from prescribed fires in South Carolina, conducting measurements at both the source and downwind to character10 ize smoke evolution with atmospheric aging. …

On-Road Heavy-Duty Vehicle Emissions Monitoring System, Gary A. Bishop, Rachel Hottor-Raguindin, Donald H. Stedman, Peter Mcclintock, Ed Theobald, Jeremy D. Johnson, Doh-Won Lee, Josias Zietsman, Chandan Misra

Fuel Efficiency Automobile Test Publications

The introduction of particulate and oxides of nitrogen (NO_x) after-treatment controls on heavy-duty vehicles has spurred the need for fleet emissions data to monitor their reliability and effectiveness. The University of Denver has developed a new method for rapidly measuring heavy-duty vehicles for gaseous and particulate fuel specific emissions. The method was recently used to collect 3,088 measurements at a Port of Los Angeles location and a weigh station on I-5 in northern California. The weigh station NO_x emissions for 2014 models are 73% lower than 2010 models (3.8 vs. 13.9 gNO_x/kg of fuel) and …

Tetrel, Chalcogen, And Ch⋅⋅O Hydrogen Bonds In Complexes Pairing Carbonyl-Containing Molecules With 1, 2, And 3 Molecules Of Co2, L. M. Azofra, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The complexes formed by H2CO, CH3CHO, and (CH3)2CO with 1, 2, and 3 molecules of CO2 are studied by ab initio calculations. Three different types of heterodimers are observed, most containing a tetrel bond to the C atom of CO2, and some supplemented by a CH⋅⋅O H-bond. One type of heterodimer is stabilized by an anti-parallel arrangement of the C=O bonds of the two molecules. The binding energies are enhanced by methyl substitution on the carbonyl, and vary between 2.4 and 3.5 kcal/mol. Natural bond orbital analysis identifies a prime source of interaction as charge transfer into the π*(CO) antibonding …

Long-Range Pcr Amplification Of Dna By Dna Polymerase Iii Holoenzyme From Thermus Thermophilus, Wendy Ribble, Shawn D. Kane, James M. Bullard

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

DNA replication in bacteria is accomplished by a multicomponent replicase, the DNA polymerase III holoenzyme (pol III HE). The three essential components of the pol III HE are the α polymerase, the β sliding clamp processivity factor, and the DnaX clamp-loader complex. We report here the assembly of the functional holoenzyme from Thermus thermophilus (Tth), an extreme thermophile. The minimal holoenzyme capable of DNA synthesis consists of α, β and DnaX ( and γ), and components of the clamp-loader complex. The proteins were each cloned and expressed in a native form. Each component of the system was purified extensively. The …

Multiple-Time Step Ab Initio Molecular Dynamics Based On Two-Electron Integral Screening, Shervin Fatehi, Ryan P. Steele

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

A multiple-timestep ab initio molecular dynamics scheme based on varying the two-electron integral screening method used in Hartree–Fock or density functional theory calculations is presented. Although screening is motivated by numerical considerations, it is also related to separations in the length- and timescales characterizing forces in a molecular system: Loose thresholds are sufficient to describe fast motions over short distances, while tight thresholds may be employed for larger length scales and longer times, leading to a practical acceleration of ab initio molecular dynamics simulations. Standard screening approaches can lead, however, to significant discontinuities in (and inconsistencies between) the energy and …

Identification And Characterization Of N-Acyltransferase Enzymes That Are Involved In The Biosynthesis Of Fatty Acid Amides, Daniel Robert Dempsey

USF Tampa Graduate Theses and Dissertations

Fatty acid amides are an emerging family of bioactive lipids that consists of N-acylethanolamines, N-acylarylalkylamides, N-acylglycines, N-acyl amino acids, N-monoacylpolyamides, and primary fatty acid amides. Short chain fatty acid amides are products of inactivated biogenic amines such as dopamine, histamine, octopamine, and serotonin, whereas long chain fatty acid amides have been implicated in a number of physiological process such as the perception and inhibition of chronic pain through binding to their specific receptors. The most famous; therefore, the most studied long chain fatty acid amide is anandamide or also known as N-arachidonylethanolamine. The biosynthesis …

Vector Space Language, Ronald Lovett

Topics in Quantum Mechanics

No abstract provided.

Design Of Organic Ternary Blends And Small-Molecule Bulk Heterojunctions: Photophysical Considerations, Kallarakkal Ramakrishnan Rajesh, Keshab Paudel, Brian Johnson, Rawad Hallani, John E. Anthony, Oksana Ostroverkhova

Chemistry Faculty Publications

We explored relationships between photophysical processes and solar cell characteristics in solution-processable bulk heterojunctions (BHJs), in particular: (1) polymer donor:fullerene acceptor:small-molecule (SM) nonfullerene acceptor, (2) polymer donor:SM donor:SM nonfullerene acceptor, and (3) SM donor:SM nonfullerene or fullerene acceptor. Addition of a nonfullerene SM acceptor to “efficient” polymer:fullerene BHJs led to a reduction in power conversion efficiency (PCE), mostly due to decreased charge photogeneration efficiency and increased disorder. By contrast, addition of an SM donor to “inefficient” polymer:SM nonfullerene acceptor BHJs led to a factor of two to three improvement in the PCE, due to improved charge photogeneration efficiency and transport. …

Comparing Three Methods For Estimating Ozone Depleting Substance Substitute Greenhouse Gases: Case Study Of The New York City Region, Wallace A. Murray Iii

Theses and Dissertations

This thesis evaluates the United States Environmental Protection Agency (EPA) method for estimating emissions from one source, Ozone Depleting Substances Substitutes (ODS substitutes) by comparing results for the New York City Metropolitan Statistical Area (NYC-MSA) with results from two other methodologies. The EPA’s method utilizes population data and GDP data to estimate and geographically allocate emissions, with little regard for the geographies of industrial activity. The two alternative methods use data for industrial employment and activity to provide results for comparison and perhaps a more accurate accounting and allocation of emissions throughout the NYC-MSA.

Enzymatic Control Of The Related Pathways Of Fatty Acid And Undecylprodiginine Biosynthesis In Streptomyces Coelicolor, Renu Singh

Dissertations and Theses

Streptomyces coelicolor produces fatty acids for both primary metabolism and for production of the components of natural products such as undecylprodiginine. Primary metabolism makes the longer and predominantly branched-chain fatty acids, while undecylprodiginine utilizes shorter and almost exclusively straight chain fatty acids. The first step in fatty acid biosynthetic process is catalyzed by FabH (β-ketoacyl synthase III), which catalyzes a decarboxylative condensation of an acyl-CoA primer with malonyl-acyl carrier protein (ACP). The resulting 3-ketoacyl-ACP product is reduced by NADPH-dependent FabG into 3-hydroxyacyl-ACP, which is dehydrated by FabA to form enoyl-ACP. The NADH-dependent FabI (InhA) completes the cycle. Subsequent rounds of …

Semiconducting Compounds And Devices Incorporating Same, Mark D. Watson

Chemistry Faculty Patents

Disclosed are semiconducting compounds having one or more phthalimide units and/or one or more head-to-head (H-H) substituted biheteroaryl units. Such compounds can be monomeric, oligomeric, or polymeric, and can exhibit desirable electronic properties and possess processing advantages including solution−processability and/or good stability at ambient conditions.

Functional Layer-By-Layer Design Of Xerogel-Based 1st Generation Amperometric Glucose Biosensors, Nicholas G. Poulos, Jackson R. Hall, Michael C. Leopold

Chemistry Faculty Publications

Xerogel-based first-generation amperometric glucose biosensors, constructed through specific layer-by-layer assembly of films featuring glucose oxidase doped xerogel, a diffusion-limiting xerogel layer, and capped with both electropolymerized polyphenol and blended polyurethane semipermeable membranes, are presented. The specific combination of xerogels formed from specific silane precursors, including propyl-trimethoxysilane, isobutyl-trimethoxysilane, octyl-trimethoxysilane, and hydroxymethyl-triethoxysilane, exhibit impressive dynamic and linear ranges of detection (e.g., ≥24–28 mM glucose) and low response times, as well as significant discrimination against common interferent species such as acetaminophen, ascorbic acid, sodium nitrite, oxalic acid, and uric acid as determined by selectivity coefficients. Additionally, systematic electrochemical and contact angle studies of …

An Experimental And Theoretical Study Of The Electronic Spectrum Of The Hbcl Free Radical, Mohammed A. Gharaibeh, Ramya Nagarajan, Dennis J. Clouthier, Riccardo Tarroni

Chemistry Faculty Publications

Following our previous discovery of the spectra of the HBX (X = F, Cl, and Br) free radicals [S.-G. He, F. X. Sunahori, and D. J. Clouthier, J. Am. Chem. Soc. 127, 10814 (2005)], the òA″Π-X̃²A' band systems of the HBCl and DBCl free radicals have been studied in detail. The radicals have been prepared in a pulsed electric discharge jet using a precursor mixture of BCl₃ and H₂ or D₂ in high pressure argon. Laser-induced fluorescence (LIF) and single vibronic level emission spectra have been recorded to map out the ground …

Preparation, Crystal Structure, Thermal Analysis, Scanning Electron Microscopy And Optical Band-Gaps Of Cu2gete4 And Cu2snte4 Alloys, Pedro Grima Gallardo, Ricardo Pena, Luis Nieves, Gustavo Marcano, Miguel Quintero, Ekadink Moreno, Jian-Han Zhang, Jacilynn A. Brant, Jennifer A. Aitken

Chemistry and Physics Faculty Articles

Polycrystalline samples (weight ~ 1g) of Cu ₂ GeTe ₄ and Cu ₂ SnTe ₄ alloys were prepared by the usual melt and anneal method and the products characterized by X-Ray Diffraction (XRD), Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM) and Optical Diffuse Reflectance UV / VIS / NIR Spectroscopytechniques. It was found that: a) Cu ₂ GeTe ₄ and Cu ₂ SnTe ₄ crystallize in an orthorhombic structure (sg Imm2; N ^o44) with lattice parameters a = 5.9281 (4) Å, b = 4.2211 (6) Å, c = 12.645 (5) Å and a = 6.0375 (6) Å, b …

Chloroamino Acids As A Chemical Explanation For Viking Labeled Release Soil Activity On Mars, John C. Hironimus

STAR Program Research Presentations

The Viking missions to Mars, which took place in the 1970’s, performed several experiments on martian soil in an attempt to discern if there was microbial life present. In one set of experiments, a nutrient solution containing amino acids and organic substrates tagged with carbon-14 was injected into sample cells containing martian soil, and the evolution of labeled CO2 was monitored. The evolution of labeled CO2 indicated that there was a process occurring that broke down the nutrients in solution and released CO2 as a byproduct. Cellular metabolism releases CO2, so this result supported the idea of microbial life on …

Stability Of Lidocaine Tested By Forced Degradation And Its Interactions With Serum Albumin, Lindsay Nichols

STAR Program Research Presentations

A concern for future long-term manned space expeditions is the ability to treat illnesses with appropriate pharmaceuticals. However, pharmaceuticals degrade faster in space than on Earth presumably due to an abundance of space radiation. The stability of Lidocaine was investigated because it is a common pain reliever currently used on the International Space Station. One of the most common proteins in blood is serum albumin, which acts as a carrier to distribute drugs throughout the body. It is important to know how well the drug binds to serum albumin so that the rate of distribution of Lidocaine-bound protein in blood …

Fabrication And Characterization Of A Vertically-Oriented Graphene Supercapacitor, Patrick R. Rice, Jiaxin Cui, Ahmad Badr, Michael M. Oye, Jessica E. Koehne, Meyya Meyyappan

STAR Program Research Presentations

Supercapacitors, otherwise known as electrical double layer capacitors, are a new type of electrochemical capacitor whose storage capacity is governed by two principals: the electrostatic storage achieved by a separation of charge at the interface of an electrode with an electrolytic solution, and pseudocapacitance, whose electrical energy is achieved by faradaic redox reactions. This project reports the synthesis and characterization of vertically-oriented graphene grown on copper substrates as electrodes in electric double-layer capacitor. Graphene is a two-dimensional pure carbon material with a high potential for energy storage. With vertically-grown graphene, an exponentially-larger surface area is made available, allowing an increase …

Genetic Encoding Of The Post-Translational Modification 2-Hydroxyisobutyryl-Lysine, William A. Knight, Thomas A. Cropp

Chemistry Publications

We report the synthesis and genetic encoding of a recently discovered posttranslational modification, 2-hydroxyisobutryl-lysine, to the genetic code of E. coli. The production of homogeneous proteins containing this amino acid will facilitate the study of modification in full-length proteins.

The Health Risks Of Chemicals In Personal Care Products And Their Fate In The Environment, Lisa Paulsen

Chemistry Honors Papers

Personal care products are everyday consumer products used to cleanse, enhance, or alter the appearance of the body, including, but not limited to, shampoos, body washes, lotions, and cosmetics. The regulations and safety information surrounding personal care products are severely lacking. The laws regulating the environmental fate of these chemicals and the harmful effects they can have on environmental ecosystems or organisms that are exposed to them are even more limited. However, studies have shown that the chemicals can have a dizzying array of health risks, including diseases on the rise in human populations such as diabetes, obesity, autism, ADHD, …