Organic Chemistry Commons^™

Simulation Studies On The Interactions Of Electron Beam With Wastewater, X. Li, S. Wang, Helmut Baumgart, G. Ciovati, F. Hannon

Electrical & Computer Engineering Faculty Publications

The manufactured chemical pollutants, like 1,4 dioxane and PFAS (per- and polyfluroralkyl substances), found in the underground water and/or drinking water are challenging to be removed or biodegraded. Energetic electrons are capable of mediating and removing them. This paper utilizes FLUKA code to evaluate the beam-wastewater interaction effects with different energy, space and divergence distributions of the electron beam. With 8 MeV average energy, the electron beam exits from a 0.0127 cm thick titanium window, travels through a 4.3 cm distance air and a second 0.0127 cm thick stainless water container window with 2.43 cm radius, and finally is injected …

Innovative Approaches In The Discovery Of Aquatic Mycobacteriophages, Janis H. Doss

Biomedical Sciences Theses & Dissertations

Bacteriophages (phages), viruses that infect bacteria, have many applications in medicine, agriculture, molecular biology, and other fields. As antibiotic resistance becomes an increasing problem, interest in phages has grown. The traditional techniques of phage discovery are successful for some phages, but others require modified procedures to achieve detectable host infection.

Mycobacterium is a diverse bacterial genus characterized by a unique cell wall containing mycolic acids, which aids in survival and pathogenesis. The aims of the present research were to isolate mycobacteriophages, use bioinformatics techniques to analyze mycobacterial prophages, and combine genetic analysis with multi-well plate host range studies to identify …

Modeling Iron And Light Controls On The Summer Phaeocystis Antarctica Bloom In The Amundsen Sea Polynya, Hilde Oliver, Pierre St-Laurent, Robert M. Sherrell, Patricia L. Yaeger

CCPO Publications

Of all the Antarctic coastal polynyas, the Amundsen Sea Polynya is the most productive per unit area. Observations from the 2010-2011 Amundsen Sea Polynya International Research Expedition (ASPIRE) revealed that both light and iron can limit the growth of phytoplankton (Phaeocystis antarctica), but how these controls manifest over the bloom season is poorly understood, especially with respect to their climate sensitivity. Using a 1-D biogeochemical model, we examine the influence of light and iron limitation on the phytoplankton bloom and vertical carbon flux at 12 stations representing different bloom stages within the polynya. Model parameters are determined by …

Pyrocumulonimbus Stratospheric Plume Injections Measured By The Ace‐Fts, C.D. Boone, Peter F. Bernath, M. D. Fromm

Chemistry & Biochemistry Faculty Publications

The Atmospheric Chemistry Experiment (ACE) is a satellite‐based mission that probes Earth's atmosphere via solar occultation. The primary instrument on board is a high‐resolution infrared Fourier transform spectrometer (Atmospheric Chemistry Experiment Fourier Transform Spectrometer, ACE‐FTS), providing altitude‐resolved volume mixing ratio measurements for numerous atmospheric constituents, including many biomass burning products. The ACE mission has observed the aftermath of three major pyrocumulonimbus events, in which extreme heat from intense fires created a pathway for directly injecting into the stratosphere plumes of gaseous and aerosol pollutants. These three events were associated with severe Australian bushfires from 2009 and 2019/2020, along with intense …

Molecular Nature Of Marine Particulate Organic Iron-Carrying Moieties Revealed By Electrospray Ionization Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (Esi-Fticrms), Chen Xu, Peng Lin, Luni Sun, Hongmei Chen, Wei Xing, Manoj Kamalanathan, Patrick G. Hatcher, Maureen H. Conte, Antonietta Quigg, Peter H. Santschi

Chemistry & Biochemistry Faculty Publications

Marine sinking particulate organic matter (POM), acting as a link between surface primary production and burial of organic matter in marine sediments, undergoes a variety of physical and biochemical alterations on its way to the deep ocean, resulting in an increase in its un-characterizable proportion with diagenesis. Further, the binding ligands in POM for iron, an essential nutrient to marine life and tightly coupled with organic matter, has rarely been studied. In the current study, we employed an approach combining sequential extraction with ultrahigh resolution mass spectrometry (ESI-FTICRMS), in order to explore and unravel the chemical characteristics of organic matter …

Influences Of Hillslope Biogeochemistry On Anaerobic Soil Organic Matter Decomposition In A Tundra Watershed, Michael Philben, Neslihan Taş, Hongmei Chen, Stan D. Wullschleger, Alexander Kholodov, David E. Graham, Baohua Gu

Chemistry & Biochemistry Faculty Publications

We investigated rates and controls on greenhouse gas (CO₂ and CH₄) production in two contrasting water‐saturated tundra soils within a permafrost‐affected watershed near Nome, Alaska, United States. Three years of field sample analysis have shown that soil from a fen‐like area in the toeslope of the watershed had higher pH and higher porewater ion concentrations than soil collected from a bog‐like peat plateau at the top of the hillslope. The influence of these contrasting geochemical and topographic environments on CO₂ and CH₄ production was tested in soil microcosms by incubating both the organic‐ and mineral‐layer …

Thyroxine Binding To Type Iii Iodothyronine Deiodinase, Craig A. Bayse, Eric S. Marsan, Jenna R. Garcia, Alexis T. Tran-Thompson

Chemistry & Biochemistry Faculty Publications

Iodothyronine deiodinases (Dios) are important selenoproteins that control the concentration of the active thyroid hormone (TH) triiodothyronine through regioselective deiodination. The X-ray structure of a truncated monomer of Type III Dio (Dio3), which deiodinates TH inner rings through a selenocysteine (Sec) residue, revealed a thioredoxin-fold catalytic domain supplemented with an unstructured Ω-loop. Loop dynamics are driven by interactions of the conserved Trp207 with solvent in multi-microsecond molecular dynamics simulations of the Dio3 thioredoxin(Trx)-fold domain. Hydrogen bonding interactions of Glu200 with residues conserved across the Dio family anchor the loop's N-terminus to the active site Ser-Cys-Thr-Sec sequence. A key long-lived loop …

Oxidation Of Aldehydes To Nitriles With An Oxoammonium Salt: Preparation Of Piperonylonitrile, Nathaniel D. Kaetzel, Kyle M. Lambert, Christopher B. Kelly

Chemistry & Biochemistry Faculty Publications

No abstract provided.

Synthesis, Characterization, And Drug Delivery Applications Of Carbohydrate Based Low Molecular Weight Gelators, Kristen Elizabeth Bashaw

Chemistry & Biochemistry Theses & Dissertations

The main aim of the research focuses on the study of self-assembly and gelation by several classes of simple sugar derivatives and the potential applications of them as drug delivery vehicles. Since carbohydrates are naturally abundant renewable resources and are therefore readily available and many of them are inexpensive compared to other raw materials. They are also biocompatible which makes them suitable for a wide variety of applications. Combining the use of carbohydrates with low molecular weight gelators (LMWGs) we can introduce a new class of soft materials that are able to self-assemble into spheres, fibers, sheets, and micelles in …

Protocol Measuring Horizontal Gene Transfer From Algae To Non-Photosynthetic Organisms, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

Horizontal gene transfer (HGT) is a natural process for an organism to transfer genetic material to another organism that is a completely different species, for example, from a blue-green alga to a non-photosynthetic bacterium. The phenomenon of HGT is not only of an interest to the science of molecular genetics and biology, but also to the biosafety issue of genetic engineering. The novel protocol reported here for the first time teaches how to measure HGT from a genetically engineered (GE) blue-green alga (gene donor) to wild-type E. coli (recipient). This novel protocol can be used to measure HGT frequency for …

Metaproteomics Reveal That Rapid Perturbations In Organic Matter Prioritize Functional Restructuring Over Taxonomy In Western Arctic Ocean Microbiomes, Molly P. Mikan, H. Rodger Harvey, Emma Timmins-Schiffman, Michael Riffle, Damon H. May, Ian Salter, William S. Noble, Brook L. Nunn

OES Faculty Publications

We examined metaproteome profiles from two Arctic microbiomes during 10-day shipboard incubations to directly track early functional and taxonomic responses to a simulated algal bloom and an oligotrophic control. Using a novel peptide-based enrichment analysis, significant changes (p-value < 0.01) in biological and molecular functions associated with carbon and nitrogen recycling were observed. Within the first day under both organic matter conditions, Bering Strait surface microbiomes increased protein synthesis, carbohydrate degradation, and cellular redox processes while decreasing C1 metabolism. Taxonomic assignments revealed that the core microbiome collectively responded to algal substrates by assimilating carbon before select taxa utilize and metabolize nitrogen intracellularly. Incubations of Chukchi Sea bottom water microbiomes showed similar, but delayed functional responses to identical treatments. Although 24 functional terms were shared between experimental treatments, the timing, and degree of the remaining responses were highly variable, showing that organic matter perturbation directs community functionality prior to alterations to the taxonomic distribution at the microbiome class level. The dynamic responses of these two oceanic microbial communities have important implications for timing and magnitude of responses to organic perturbations within the Arctic Ocean and how community-level functions may forecast biogeochemical gradients in oceans.

Conformational Flexibility In The Enterovirus Rna Replication Platform, Meghan S. Warden, Kai Cai, Gabriel Cornilescu, Jordan E. Burke, Komala Ponniah, Samuel E. Butcher, Steven M. Pascal

Chemistry & Biochemistry Faculty Publications

A presumed RNA cloverleaf (5′CL), located at the 5′-most end of the noncoding region of the enterovirus genome, is the primary established site for initiation of genomic replication. Stem–loop B (SLB) and stem–loop D (SLD), the two largest stem–loops within the 5′CL, serve as recognition sites for protein interactions that are essential for replication. Here we present the solution structure of rhinovirus serotype 14 5′CL using a combination of nuclear magnetic resonance spectroscopy and small-angle X-ray scattering. In the absence of magnesium, the structure adopts an open, somewhat extended conformation. In the presence of magnesium, the structure compacts, bringing SLB …

Formation Of Water-Soluble Organic Matter Through Fungal Degradation Of Lignin, Seyyedhadi Khatami, Ying Deng, Ming Tien, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

Lignin is a major component of decaying terrestrial vegetation in soils and has been reported to contribute substantially to the formation of soil carbon humus and associated water extracts of soil. To better understand this process of humification, lignin from brown-rot degraded wood is subjected to a white-rot fungus (Phanerochaete chrysosporium)whose enzymes are particularly effective in lignin degradation. This enzymatic attack was monitored by ultrahigh resolution mass spectrometry of water soluble extracts of the fungal cultures. The ensuing molecular level characterizations showed that the P. chrysosporium fungi induced aromatic ring oxidations followed by ring opening as expected. However, …

The Tides They Are A-Changin': A Comprehensive Review Of Past And Future Nonastronomical Changes In Tides, Their Driving Mechanisms, And Future Implications, Ivan D. Haigh, Mark D. Pickering, J. A. Mattias Green, Brian K. Arbic, Arne Arns, Sönke Dangendorf, David F. Hill, Kevin Horsburgh, Tom Howard, Déborah Idier, David A. Jay, Leon Jänicke, Serena B. Lee, Malte Müller, Michael Schindelegger, Stefan A. Talke, Sophie-Berenice Wilmes, Philip L. Woodworth

CCPO Publications

Scientists and engineers have observed for some time that tidal amplitudes at many locations are shifting considerably due to nonastronomical factors. Here we review comprehensively these important changes in tidal properties, many of which remain poorly understood. Over long geological time scales, tectonic processes drive variations in basin size, depth, and shape and hence the resonant properties of ocean basins. On shorter geological time scales, changes in oceanic tidal properties are dominated by variations in water depth. A growing number of studies have identified widespread, sometimes regionally coherent, positive, and negative trends in tidal constituents and levels during the 19th, …

Functionality Of Membrane Proteins Overexpressed And Purified From E. Coli Is Highly Dependent Upon The Strain, Khadija Mathieu, Waqas Javed, Sylvain Vallet, Christian Lesterlin, Marie-Pierre Candusso, Feng Ding, Xiaohong Nancy Xu, Christine Ebel, Jean-Michel Jault, Cédric Orelle

Chemistry & Biochemistry Faculty Publications

Overexpression of correctly folded membrane proteins is a fundamental prerequisite for functional and structural studies. One of the most commonly used expression systems for the production of membrane proteins is Escherichia coli. While misfolded proteins typically aggregate and form inclusions bodies, membrane proteins that are addressed to the membrane and extractable by detergents are generally assumed to be properly folded. Accordingly, GFP fusion strategy is often used as a fluorescent proxy to monitor their expression and folding quality. Here we investigated the functionality of two different multidrug ABC transporters, the homodimer BmrA from Bacillus subtilis and the heterodimer PatA/PatB …

Exomol Line List - Xxxiv. A Rovibrational Line List For Phosphinidene (Ph) In Its X³Σ¯ And A¹Δ Electronic States, Jonathan Langleben, Jonathan Tennyson, Sergei N. Yurchenko, Peter Bernath

Chemistry & Biochemistry Faculty Publications

A rovibronic line list for the ground (X³Σ⁻) and first excited (a¹Δ) states of phosphinidene, ³¹PH, is computed. The line list is designed for studies of exoplanetary and cool stellar atmospheres with temperatures up to 4000 K. A combination of empirical and ab initio data is used to produce the line list: potential energy curves (PECs) are fitted using experimental transition frequencies; these transitions are reproduced with a root mean square error of 0.01 cm⁻¹. The nuclear Schrödinger equation is solved using these PECs plus Born–Oppenheimer and spin splitting correction terms. …

Shelf Inputs And Lateral Transport Of Mn, Co, And Ce In The Western North Pacific Ocean, Peter L. Morton, William M. Landing, Alan M. Shiller, Amy Moody, Thomas D. Kelly, Michael Bizimis, John R. Donat, Eric H. De Carlo, Joseph Shacat

Chemistry & Biochemistry Faculty Publications

The margin of the western North Pacific Ocean releases redox-active elements like Mn, Co, and Ce into the water column to undergo further transformation through oxide formation, scavenging, and reductive dissolution. Near the margin, the upper ocean waters enriched in these elements are characterized by high dissolved oxygen, low salinity, and low temperature, and are a source of the North Pacific Intermediate Water. High dissolved concentrations are observed across the Western Subarctic Gyre, with a rapid decrease in concentrations away from the margin and across the subarctic-subtropical front. The particulate concentrations of Mn, Co, and Ce are also high in …

Condensation And Polymerization Explain The Humification Of Lignin Into Aliphatic And Aromatic Structures In Soil, Patrick G. Hatcher, Hongmei Chen, Seyyedhadi Khatami, Derek C. Waggoner

Chemistry & Biochemistry Faculty Publications

Soil organic matter (SOM) constitutes a global reservoir of carbon that is more than twice that of either atmospheric carbon or aquatic carbon; however, the manner in which it forms from degraded plant biomass is poorly understood. Some have recently questioned whether plant biomass is involved directly in SOM formation and suggest that it is microbial carbon that constitutes the main source of stable SOM. Such a view implies that above and below ground plant biomass is rapidly decomposed and mineralized. This view contrasts significantly with traditional ones that involve the transformation of plant biomass to recalcitrant humic materials fueled …

Advances In Amino Acid Analysis For Marine Related Matrices And Its Application To Coastal Shelf Settings In The Canadian Arctic, Rachel M. Mcmahon

OES Theses and Dissertations

Amino acids comprise up to 50% of organic matter in cellular material and are a major fraction of oceanic organic carbon. Amino acids are also considered highly labile during organic matter recycling, making them useful proxies for organic carbon cycling. Nevertheless, analysis of individual amino acids has been burdened by lengthy derivatization and complex analysis since the 1950s. In this thesis, I describe the modification of advanced analytical techniques, developed in the biomedical field, for analysis of marine matrices which allow the determination of at least 40 amino acids without the need for lengthy sample preparation and derivatization, twice the …

Effect Of Curing Rate On The Microstructure And Macroscopic Properties Of Epoxy Fiberglass Composites, Ammar Patel, Olesksandr Kravchenko, Ica Manas-Zloczower

Mechanical & Aerospace Engineering Faculty Publications

Curing rates of an epoxy amine system were varied via different curing cycles, and glass-fiber epoxy composites were prepared using the same protocol, with the aim of investigating the correlation between microstructure and composite properties. It was found that the fast curing cycle resulted in a non-homogenous network, with a larger percentage of a softer phase. Homogenized composite properties, namely storage modulus and quasi-static intra-laminar shear strength, remained unaffected by the change in resin microstructure. However, fatigue tests revealed a significant reduction in fatigue life for composites cured at fast curing rates, while composites with curing cycles that allowed a …

Surface Oxygenation Of Biochar Through Ozonization For Dramatically Enhancing Cation Exchange Capacity, Matthew D. Huff, Sarah Marshall, Haitham A. Saeed, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

Background

Biochar cation exchange capacity (CEC) is a key property that is central to biochar environmental applications including the retention of soil nutrients in soil amendment and removal of certain pollutants in water-filtration applications.

Results

This study reports an innovative biochar-ozonization process that dramatically increases the CEC value of biochars by a factor of 2. The ozonized biochars also show great improvement on adsorption of methylene blue by as much as a factor of about 5. In this study, biochar samples treated with and without ozone were analyzed by means of pH and CEC assays, water field capacity measurement, elemental …

Synthesis And Characterization Of Glycolipids, Glycoclusters And Glycomacrocycles, Anji Chen

Chemistry & Biochemistry Theses & Dissertations

Low molecular-weight gelators (LMWGs) are a fascinating and interesting class of compounds that can self-assemble and form supramolecular structures in appropriate solvents. The gelators form fibrous networks which entrap the solvent and result in a supramolecular gel. Carbohydrate-derived LMWGs are especially useful since they are more likely to be biocompatible and biodegradable. Dendritic gelators are branch-shaped molecules with precise molecular weight that are between small molecules and polymer gelators. Glycoclusters with sugar moieties at the periphery of the molecules are important classes of bioactive compounds due to the multivalency effect. Lower generation glycoclusters are relatively small branched systems that have …

Synthesis, Characterization And Application Of Sugar-Based Low Molecular Weight Gelators, Ifeanyi Simeon Okafor

Chemistry & Biochemistry Theses & Dissertations

Low molecular weight gelators (LMWGs) are an interesting class of compound that have gained considerable attention especially because of their potential applications for soft biomaterials. Carbohydrate based low molecular weight hydrogelators and organogelators are able to selfassemble and form ordered supramolecular structures, which are useful for exploring biomedical applications. The resulting gelators are responsive to external stimuli because of the weak noncovalent intermolecular forces and interaction that influences self-assembly. Stimuli-responsive supramolecular organogels with interesting properties in response to external environmental stimuli have gained considerable attention due to their applications in biomaterials, sensors and for drug delivery.

One of the major …

Characterization Of 3-Ester And 3-Carbamate Derivatives Of N-Acetyl-D-Glucosamine And Their Use In Controlled Drug Delivery, Consuelo Garcia

Chemistry & Biochemistry Theses & Dissertations

Low molecular weight gelators (LMWGs) are a class of compounds which reversibly form a network that traps solvents to form gels. Gelation by LMWGs is driven solely by non-covalent interactions such as hydrogen bonding, π - π stacking, and hydrophobic interactions. LMWGs can be designed such that the gel-sol and sol-gel transitions happen as a response to a specific stimulus. These stimulus responsive gels or “smart” gels can be used in a wide variety of applications including tissue regeneration, biosensing, and controlled drug delivery.

Among the different types of compounds that are LMWGs, carbohydrate based systems are especially interesting. Carbohydrates …

Synthesis And Characterization Of Amide Linked Triazolyl Glycolipids As Molecular Hydrogelators And Organogelators, Guijun Wang, Anji Chen, Hari P. R. Mangunuru, Jayasudhan Reddy Yerabolu

Chemistry & Biochemistry Faculty Publications

Carbohydrate based small molecular gelators are important classes of compounds which can form useful soft materials with many practical applications. Although many different types of effective gelators have been reported, the rational design of a molecular hydrogelator is still challenging. In this research, we combined the structural features of two classes of monosaccharide based molecular gelators and obtained a new class of glycolipids that can function as molecular gelators. These new compounds were synthesized by introducing a triazole functional group to a protected 2-glucosamine through Cu(i) catalyzed azide/alkyne cycloaddition reaction (CuAAC). A series of eighteen new glycolipids containing 4,6-O …

Low-Temperature Artificial Maturation Studies Of Type Ii And Type Iii Kerogens: Implications For Biogenic Gas Production, Albert Willy Nguena Kamga

Chemistry & Biochemistry Theses & Dissertations

Ancient organic matter (OM) in shales and coals, known mainly as Type II and Type III OM are known to produce both biogenic, thermogenic gas and oil. In this dissertation, mild artificial maturation, via closed system pyrolysis, is employed to determine the thermal reactivity of Type II and Type III OM beyond diagenesis. We select three Type II kerogens: i) Type II kerogen isolated from recent cores (3.3 Ma, Ro = 0.28) recovered from an upwelling basin in Namibia, Africa referred to as ODP Sediment, ii) Type II-S isolated from sediments (150 Ma, Ro = 0.38) recovered from an outcrop …

Synthesis, Morphological Control, Dispersion Stabilization And In Situ Self-Assembly Of Noble Metal Nanostructures Using Multidentate Resorcinarene Surfactants, Sangbum Han

Chemistry & Biochemistry Theses & Dissertations

In this dissertation, a detailed investigation on the influence of various macrocyclic resorcinarene surfactants in determining the morphology, stabilization and self-assembly of mono- and bi- metallic nanoparticles was undertaken. Chapter 2 describes the influence of resorcinarene surfactants functionalized with amine- and thiol- headgroups in determining the morphology of monometallic Pt nanoparticles synthesized via the Brust-Schiffrin reaction. We found that while resorcinarene benzylthiol can lead to the formation of highly branched Pt nanostructures, resorcinarene amine can lead to the formation of anisotropic crystalline Pt nanoparticles. Further, we have evaluated the influence of resorcinarene ligands in determining the catalytic activity of these …

Single Nanoparticle Plasmonic Spectroscopy For Study Of The Efflux Function Of Multidrug Abc Membrance Transporters Of Single Live Cells, Lauren M. Browning, Kerry J. Lee, Pavan K. Cherukuri, Prakash D. Nallathamby, Seth Warren, Jean-Michel Jault, Xiao-Hong Nancy Xu

Chemistry & Biochemistry Faculty Publications

ATP-binding cassette (ABC) membrane transporters exist in all living organisms and play key roles in a wide range of cellular and physiological functions. The ABC transporters can selectively extrude a wide variety of structurally and functionally unrelated substrates, leading to multidrug resistance. Despite extensive study, their efflux molecular mechanisms remain elusive. In this study, we synthesized and characterized purified silver nanoparticles (Ag NPs) (97 ± 13 nm in diameter), and used them as photostable optical imaging probes to study efflux kinetics of ABC membrane transporters (BmrA) of single live cells (B. subtilis). The NPs with concentrations up to …

Anticancer, Biophysical And Computational Investigations Of Half-Sandwich Ruthenium(Ii) Thiosemicarbazone Complexes: The Effect Of Arene Versus Thiacrown Face-Cap, Floyd A. Beckford, Alyssa Stott, P. Canisius Mbarushimana, Marc-Andre Leblanc, Kinsey Hall, Samantha Smith, Jimmie L. Bullock, Dennis J. Houghton, Alvin A. Holder, Nikolay Gerasimchuk, Antonio Gonzalez-Sarrías

Chemistry & Biochemistry Faculty Publications

A series of half-sandwich ruthenium complexes, two containing an arene face-cap and the other a thiacrown ether face-cap were synthesized to investigate the necessity of the arene for anticancer activity in this class of compounds. The complexes are formulated as [(h⁶-p-cymene)Ru(dmabTSC)Cl]PF₆, [(h⁶-benzene)Ru(dmabTSC)Cl]PF₆ (arene complexes), and [([9]aneS₃(dmabTSC)Cl]PF₆ (dmabTSC = dimethylaminobenzaldehye thiosemicarbazone). It was observed that none of the complexes showed good anticancer activity in vitro against HCT-116 and Caco-2 (colon adenocarcinoma) cells. All three complexes can bind strongly to calf-thymus DNA with binding constants on the order of 10 …

Effect Of Methoxy Substituents On The Activation Barriers Of The Glutathione Peroxidase-Like Mechanism Of An Aromatic Cyclic Seleninate, Craig A. Bayse, Ashley L. Shoaf

Chemistry & Biochemistry Faculty Publications

Density functional theory (DFT) models including explicit water molecules have been used to model the redox scavenging mechanism of aromatic cyclic seleninates. Experimental studies have shown that methoxy substitutions affect the rate of scavenging of reactive oxygen species differently depending upon the position. Activities are enhanced in the para position, unaffected in the meta, and decreased in the ortho. DFT calculations show that the activation barrier for the oxidation of the selenenyl sulfide, a proposed key intermediate, is higher for the ortho methoxy derivative than for other positions, consistent with the low experimental conversion rate.