Chemistry Commons^™

Chemical Speciation In Silver Bow And Blacktail Creeks: Implications For Bioavailability And Restoration, Johnathan Feldman

Graduate Theses & Non-Theses

Silver Bow and Blacktail Creeks, contaminated with toxic elements from mining, present a need for remediation and restoration. Trace elements are present in elevated concentrations, particularly copper. Determining element speciation will allow informed consideration of effective restoration strategies, by providing a foundation for assessing bioavailability and toxicity. The three goals are: determine how speciation varies between seasons and sites in four impacted sites from the greater Butte Area One, an impacted downstream site known as Santa, and a control site on Upper Blacktail Creek known as Blacktail; how these variations influence bioavailability and toxicity; and what causes these variations. Total …

Biochemical Investigations Of Proteins Associated With Iron Homeostasis In Escherichia Coli, Matthew Ryan Blahut

Theses and Dissertations

The regulation of transition metals within living organisms is essential to the persistence of life. Of particular interest to our lab is iron due to the prevalence of this metal within the cell in addition to the numerous functions it performs. Fe-S cofactors are a significant prosthetic group consisting of iron that are necessary for the function of various metalloproteins. Generation of Fe-S clusters depends on several biosynthesis pathways varying between organisms with Isc and Suf both utilized in E. coli. While Isc controls Fe- S manufacturing under normal conditions, Suf assumes control when the cell is exposed to …

Caspases And Cancer: Connections Through Circular Dichroism Spectroscopy, Sarah M. Hethcox

Honors College Theses

While excessive cell death inevitably leads to negative effects, the endurance of damaged cells in the presence of death signals can be equally detrimental to health. Apoptosis, or programmed cell death, is a highly regulated process in which cues from within or from outside a cell can trigger an irreversible sequence of signals that carry out cell destruction known as the apoptotic cascade. A group of enzymes called caspases play a vital role in this cascade with some participating as initiators and others acting as effectors of protein cleavage and intracellular breakdown. Although it is normal for the activity of …

Effect Of Iron On The Oxidative Capacity Of Carbonaceous Nanoparticles, Daniel Chavez

All Master's Theses

Inhalation of ambient particulate matter (PM_2.5) emitted during combustion of fuels has negative impacts on human health. Triggered in part by the generation of reactive oxygen species (ROS) that lead to oxidative stress, significant gaps exist in the understanding of the detailed chemistry of these detrimental effects. Trace metals and carbonaceous material of the nanometer-sized particles contained in PM_2.5 have been implicated as key players in causing these effects. Here, the role of Fe is investigated with carbonaceous nanoparticles (CNP) while mimicking simple cellular conditions. By adding environmentally representative and controlled concentrations of Fe(II) or Fe(III) to …

Nickel Exposure Reduces Enterobactin Production In Escherichia Coli, Clorissa L. Washington-Hughes, Geoffrey T. Ford, Alsten D. Jones, Kimberly Mcrae, Franklin Wayne Outten

Faculty Publications

Escherichia coli is a well- studied bacterium that can be found in many niches, such as industrial wastewater, where the concentration of nickel can rise to low- millimolar levels. Recent studies show that nickel exposure can repress pyochelin or induce pyo-verdine siderophore production in Pseudomonas aueroginosa. Understanding the mo-lecular cross- talk between siderophore production, metal homeostasis, and metal toxicity in microorganisms is critical for designing bioremediation strategies for metal- contaminated sites. Here, we show that high- nickel exposure prolongs lag phase duration as a result of low- intracellular iron levels in E. coli. Although E. coli cells respond to low- …

Nickel Exposure Reduces Enterobactin Production In Escherichia Coli, Clorissa L. Washington – Hughes, Geoffrey T. Ford, Alsten D. Jones, Kimberly Mcrae, Franklin W. Outten

Faculty Publications

Escherichia coli is a well- studied bacterium that can be found in many niches, such as industrial wastewater, where the concentration of nickel can rise to low- millimolar levels. Recent studies show that nickel exposure can repress pyochelin or induce pyo-verdine siderophore production in Pseudomonas aueroginosa. Understanding the mo-lecular cross- talk between siderophore production, metal homeostasis, and metal toxicity in microorganisms is critical for designing bioremediation strategies for metal- contaminated sites. Here, we show that high- nickel exposure prolongs lag phase duration as a result of low- intracellular iron levels in E. coli. Although E. coli cells respond to low- …

Synthesis And Catalytic Activity Of (3,4-Diphenylcyclopentadienone)Iron Tricarbonyl Compounds In Transfer Hydrogenations And Dehydrogenations, Timothy W. Funk, Andrew R. Mahoney, Rebecca A. Sponenburg, Kathryn P. Zimmerman, Daniel K. Kim, Emily E. Harrison

Chemistry Faculty Publications

Four (3,4-diphenylcyclopentadienone)iron tricarbonyl compounds were synthesized, and their activities in transfer hydrogenations of carbonyl compounds and transfer dehydrogenations of alcohols were explored and compared to those of the well-established [2,5-(SiMe3)2-3,4-(CH2)4(η4-C4C═O)]Fe(CO)3 (3). A new compound, [2,5-bis(3,5-dimethylphenyl)-3,4-diphenylcyclopentadienone]iron tricarbonyl (7), was the most active catalyst in both transfer hydrogenations and dehydrogenations, and compound 3 was the least active catalyst in transfer hydrogenations. Evidence was found for product inhibition of both 3 and 7 in a transfer dehydrogenation reaction, with the activity of 3 being more heavily affected. A monomeric iron hydride derived from 7 was spectroscopically observed during a …

Systematic Size Control In The Synthesis Of Zero-Valent Iron Nanoparticles, Grant C. Bleier

Chemistry and Chemical Biology ETDs

A novel synthetic method for the production of highly magnetic, low size-dispersity nanoparticles through reversible magnetic agglomeration is introduced and studied in detail. Initially, a weakly coordinating surfactant (3-octadecyl-2,4-pentanedione) is employed to produce a wide range of nanoparticle sizes ranging from 8 to 20 nm in diameter. The kinetics faced in these reactions by cheap and widely available iron complex precursors can be avoided in this method with the introduction of thermodynamic control, which occurs in the form of a magnetic precipitation event that essentially halts nanoparticle growth. Utilizing this synthetic method, the length of the alkyl chain on the …

Efficient Reductive Claisen Rearrangement Of Prop-2'-Enyloxyanthraquinones And 2'-Chloroprop-2'-Enyloxyanthraquinones With Iron Powder In Ionic Liquids, Samaneh Nadali, Ali Khoshroo, Ghasem Aghapour

Turkish Journal of Chemistry

A rapid and selective iron-mediated reductive Claisen rearrangement of various prop-2'-enyloxyanthraquinones and 2'-chloroprop-2'-enyloxyanthraquinones to 1-hydroxy-2-(prop-2'-enyl)anthraquinones and anthrafurandiones is presented. All reactions are carried out in a mixture of ionic liquids, [Bzmim]Cl (1-benzyl-3-methylimidazolium chloride) and [Hmim]BF$_{4}$ (1-methylimidazolium tetrafluoroborate), in short reaction times (5-35 min). Our study showed that 1-(prop-2'-enyloxy)anthraquinone is more active than 1-(2'-chloroprop-2'-enyloxy)anthraquinone to perform this rearrangement.

The Chemistry And Biology Of Iron-Scavenging Natural Products From Pathogenic Acinetobacter Baumannii, Justin Shapiro

Arts & Sciences Graduate Student Theses and Dissertations

Multidrug resistant (MDR) Gram-negative bacteria represent a global health crisis. Traditional antibiotics create selective pressure and breed resistance, making our current drugs less and less effective. Targeting of bacterial virulence factors has gained interest as an alternative strategy to potentially circumvent this problem. Virulent Acinetobacter baumannii synthesize and secrete pre-acinetobactin, a small molecule metal chelator that scavenges life-sustaining iron and is critical for establishing infection. The work described herein sheds light on the unusual properties of a non-enzymatic isomerization from pre-acinetobactin to acinetobactin and proposes a siderophore-swapping mechanism by which A. baumannii expands its pH window for virulence. Knowledge from …

Altering The Coordination Of Iron Porphyrins By Ionic Liquid Nanodomains In Mixed Solvent Systems, Abderrahman Atifi, Michael D. Ryan

Chemistry Faculty Research and Publications

The solvent environment around iron porphyrin complexes was examined using mixed molecular/RTIL (room temperature ionic liquid) solutions. The formation of nanodomains in these solutions provides different solvation environments for substrates that could have significant impact on their chemical reactivity. Iron porphyrins (Fe(P)), whose properties are sensitive to solvent and ligation changes, were used to probe the molecular/RTIL environment. The addition of RTILs to molecular solvents shifted the redox potentials to more positive values. When there was no ligation change upon reduction, the shift in the E° values were correlated to the Gutmann acceptor number, as was observed for other …

Ultrasonic Activation Of The Arylation Reaction Of Styrene Catalyzed By Transition Metals, Dhiab Atoui, Khemais Said, Ridha Ben Salem

Turkish Journal of Chemistry

The arylation reaction of styrene was tested in the presence of different transition metal-based catalysts, mainly iron-based, given its low cost and its nonpolluting and nontoxic characteristics. The study of the effect of sonochemical activation on the evolution of the selectivity of the reaction is also proposed. Higher efficiency was observed for a very short period of time of just a few minutes. Furthermore, an improvement of the selectivity of the arylation of the external carbon of styrene was observed.

Phytoplankton Plastid Proteomics: Cracking Open Diatoms To Understand Plastid Biochemistry Under Iron Limitation, Skyler J. Nunn, Phoebe Dreux Chappell, Kristofer Gomes, Anasthasia Bonderenko, Bethany D. Jenkins, Brook L. Nunn

OES Faculty Publications

Diatoms, such as Thalassiosira pseudonana, are important oceanic primary producers, as they sequester carbon dioxide (CO₂) out of the atmosphere, die, and precipitate to the ocean floor. In many areas of the world’s oceans, phytoplankton, such as diatoms, are limited in growth by the availability of iron (Fe). Fe is an essential nutrient for phytoplankton, as it is central in the electron transport chain component of photosynthesis. Through this study, we examined if Fe-limitation makes a significant difference in the proteins expressed within the chloroplast, the power source for diatoms. Here, we utilized a new plastid isolation technique specific …

Mild Hydrofunctionalizations Of Olefins Using More Cost-Effective Metal Catalysts, Alexander James Villani-Gale

Dissertations

The focus of this dissertation is the study of alkene hydroaylation reactions. In the first chapter, a review of the relevant literature concerning zinc- and iron-catalyzed hydroarylation of unsaturated bonds is presented. In chapter two, the development of a zinc-catalyzed hydroarylation of alkenes is presented, which is quickly followed by a detailed investigation into the probable mechanism. Chapter three discusses the development of an iron/silver-catalyzed arene prenylation reaction, followed by the development of an iron/zinc-catalyzed arene prenylation reaction. The final section of chapter three discusses the adaptation of the iron/zinc-catalyzed arene prenylation into an undergraduate organic teaching laboratory.

Conversion Of Cafo Manure Into A Slow-Release Fertilizer, Richard Allan Williams Iii

Honors Projects

Alginate polymer is known to form gel through the process of Ionotropic gelation. By use of extrusion and diffusion setting manure was encapsulated into gel beads. These beads were then tested to determine their potential for further testing as a manure treatment process. From the limited data in this preliminary study, it appears as though there is potential for further testing of alginate beads as a treatment process for manure. The treatment is potentially valuable because of the ease of filtration of the alginate beads, the low cost of transportation of the dehydrated beads, and because the limited data suggests …

Studies On Hydroxyl Radical Formation And Correlated Photoflocculation Process Using Degraded Wood Leachate As A Cdom Source, Luni Sun, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

In this study, we examined hydroxyl radical (•OH) formation with respect to photoreactivity of colored dissolved organic matter (CDOM), the Fenton reaction, and photoflocculation using leachate from decaying wood. The relationship between •OH photoproduction rate and leachate optical properties (UV-visible absorption and fluorescence excitation-emission matrices (EEMS)) was studied during irradiation using a UV solar simulator. The results showed that the •OH photochemical formation rate is strongly related to humic-like fluorescence as characterized by parallel factor analysis (PARAFAC), and that these fluorescence components are more photolabile than most of the other CDOM components. Fourier transform infrared spectroscopy (FT-IR) indicated the photodegradation …

Versatile Synthesis Of Transition Metal Phosphides: Emerging Front-Runners For Affordable Catalysis, April C. Mattei

Theses and Dissertations

Transition metal phosphide materials have found themselves at the forefront of research revolving around energy applications. Due to the vast range of properties possessed by marginally different phase compositions, binary and ternary metal phosphides are utilized as catalysts, semi-conductors and magnetocaloric materials along with many others. These attractive properties, which are highly phase dependent, call for a versatile and cost effective synthesis route for various phosphide materials without sacrificing properties important at the nanoscale such as particle size and morphology.

The primary focus outlined in the work of this dissertation pertains to a versatile wet chemical synthesis capable of producing …

X-Ray Structure And Properties Of The Ferrous Octaethylporphyrin Nitroxyl Complex, Nagabhushanam Kundakarla, Sergey V. Lindeman, Hafiz Md. Rahman, Michael D. Ryan

Chemistry Faculty Research and Publications

The preparation and characterization of the iron octaethylporphyrin nitroxyl ion, [Fe(OEP)(NO)⁻], is reported. The complex was synthesized by the one-electron reduction of Fe(OEP)(NO) using anthracenide as the reducing agent. The compound was isolated as the potassium (2.2.2)cryptand salt. The anion was characterized using X-ray analysis with visible and infrared spectroscopy. The spectral features of the iron nitroxyl complex were consistent with previous literature reports. The important structural changes upon reduction were a significant decrease in the Fe–N–O bond angle from 142° to 127° and an increase in the N–O bond length from that in the starting nitrosyl moiety. …

A Review On The Bulk And Surface Chemistry Of Iron In Atmospherically-Relevant Systems Containing Humic Like Substances (Hulis), Hind A. Al-Abadleh

Chemistry Faculty Publications

As the fourth most abundant element by mass in the Earth’s crust, iron is ubiquitous and its chemistry is rich and interdisciplinary in nature. This review synthesizes the current state of knowledge of iron chemistry in multicomponent atmospheric aerosols, which is also applicable to other atmospherically-relevant systems that include iron-containing anthropogenic nanodust, ocean surfaces and buildings. Because of the abundance of humic-like substances (HULIS) in these systems, studies on their chemistry with iron and those used as models for HULIS are the focus of this review. Findings from field measurements and laboratory studies are summarized to highlight major themes in …

Kinetics Study And Influence Of Water-Soluble Polymer On The Electrodeposition Of Iron From A Citrate-Chloride Electrolyte On The Basis Of Fe(Iii), Vyacheslav Protsenko, Felix Danilov

Turkish Journal of Chemistry

The kinetics of the iron electrodeposition reaction from a plating bath containing trivalent iron ions is investigated in the present work. The electrochemical reaction is stated to proceed via the formation of relatively stable intermediates: Fe(II) ions. Only a part of the total amount of Fe(II) ions formed at the first stage of Fe(III) discharge is reduced further, producing metal iron. The effect of polyhexamethyleneguanidine hydrochloride (with an average molecular weight of 1000) on the iron deposition is ascertained. The presence of polymer additive in the iron electrolyte appreciably affects the rate of iron deposition, while the polymer additive does …

Illuminating The Interactions And Functions Of Glutaredoxins, Bola Proteins, And Erv1 In Iron Homeostasis, Adrian Colleen Dlouhy

Theses and Dissertations

Iron is a redox-active protein cofactor required for essential cellular functions such as respiration, however excess intracellular iron can generate damaging reactive oxygen species. Understanding how cells regulate iron levels is critical for treatment of human diseases that span from anemia to iron overload disorders. Glutaredoxins (Grxs) with a CGFS active site are highly conserved proteins shown to have roles in iron homeostasis and iron-sulfur cluster assembly, thus earning them the title “the Iron Whores”. They can exist either as a [2Fe-2S] cluster-bound dimer or an apo monomer, suggesting conservation of structure and function. In addition, Grxs interact with the …

Phosphorous Acid Route Synthesis Of Iron Tavorite Phases, Lifepo₄(Oh)ₓf₁₋ₓ [0 ≤ X ≤ 1] And Comparative Study Of Their Electrochemical Activities, Hooman Yaghoobnejad Asl, Amitava Choudhury

Chemistry Faculty Research & Creative Works

New synthesis routes were employed for the synthesis of three derivatives of iron hydroxo-, fluoro-, and mixed hydroxo-fluoro phosphates LiFePO ₄(OH)_xF_1-x where 0 ? x ? 1 with the tavorite structure type, and their detail electrochemical activities have been presented. The hydrothermal synthesis of the pure hydroxo-derivative, LiFePO₄OH, using phosphorous acid as a source of phosphate yielded good quality crystals from which the crystal structure was solved for the first time using SC-XRD (single crystal X-ray diffraction). The fluoro derivative, LiFePO₄F, was prepared as a very fine powder at low temperature in …

Investigations Of Synthetic Models Of Mononuclear Nonheme Iron Dioxygenases, Michael Bittner

Dissertations (1934 -)

Ring cleaving dioxygenases, such as o-aminophenol dioxygenase (APDO) and extradiol catechol dioxygenases (CatD), play an important role in human metabolism and the degradation of aromatic pollutants, yet questions still remain concerning the enzymatic mechanisms. One area of the catalytic cycle that remains controversial is the geometric and electronic structure of the intermediate formed after O₂ binding to the Fe(II) centers. Synthetic model systems can be useful for studying enzyme active sites, as they are easier to modify and characterize than the enzymes themselves. However, synthetic models of APDOs have been relatively rare thus far. We prepared several monoiron(II) complexes …

The Location And Role Of Phosphate In Horse Spleen Ferritin (Hosf), Joseph Johnson

Journal of Undergraduate Research

Although iron Is necessary for life, It Is toxic If left free In most organIsms. To control Its toxic effects and still have iron available for biological use, organisms use ferrltins. Ferritins are similar throughout the biological world. Each ferritin is a roughly spherical, hollow protein with a thin, negatively charged shell that can hold up to 4500 Iron atoms. This shell is composed of 24 nearly Identical subunits. Junctions between three or four subunits form channels, 3-fold or 4-fold respectively, that traverse the protein shell. The hydrophilic 3-fold channels are believed to be the key pathway for the uptake …

Ionic Liquid Extraction Unveils Previously Occluded Humicbound Iron In Peat Porewater, Timothy J. Veverica

Dissertations, Master's Theses and Master's Reports - Open

Extracellular iron reduction has been suggested as a candidate metabolic pathway that may explain a large proportion of carbon respiration in temperate peatlands. However, the o-phenanthroline colorimetric method commonly employed to quantitate iron and partition between redox species is known to be unreliable in the presence of humic and fulvic acids, both of which represent a considerable proportion of peatland dissolved organic matter. We propose ionic liquid extraction as a more accurate iron quantitation and redox speciation method in humic-rich peat porewater. We evaluated both o-phenanthroline and ionic liquid extraction in four distinct peatland systems spanning a gradient of physico-chemical …

Syntheses And Structures Of Iron(Ii) And Cobalt(Ii) Complexes Of Substituted Tetra(Pyrazolyl)Lutidine Derivatives, Heidi Marie Tatlock

Master's Theses (2009 -)

Pentadentate ligands provide stability to metal complexes as well as a binding site for substrates that make them exceptionally useful for studying reactions. They have been used in biomimetic studies, water splitting, and small molecule activation studies. A series of six pentadentate ligands derived from a,a,a',a'-tetra(pyrazolyl)lutidine, pz4lut, with methyl substituents decorating the ligand periphery has been synthesized. These ligands were coordinated to FeIICl, and the electronic and structural properties of the resulting complexes were studied in order to deduce the effects of methyl substitution at the 3-, 4-, and 5-positions of the pyrazolyl groups and at the methine positions. When …

Redox Properties Of Horse Spleen Ferritin, D. Cope Norcross, Dr. Gerald D. Watt

Journal of Undergraduate Research

Iron is essential to all forms of life. Yet, free iron is toxic unless sequestered and regulated. Organisms use the protein ferritin to perform this function. Ferritin is found storing and releasing iron in almost all living organisms. Ferritin is a large, nearly spherical, hollow protein composed of twenty-four nearly identical subunits (Harrison, et. al., 1991; Theil, 1990). The structure of this protein has been characterized and is well known, yet relating this form to its function is still an active area of research. Although there have been many studies done and many models proposed, very little is known about …

X-Ray Crystal Structures Of: [Rh2(N-{2,4,6-Ch3}C6h2)Coch3)4]•2ncc6h4 And Ba1.5[Fe(C10h13n2o7)][Co(Cn)6]•9h2o; Two Crystallographic Challenges, Kenneth K. Kpogo

Electronic Theses and Dissertations

The novel compound, [Rh₂(N-{2,4,6-CH₃}C₆H₂)COCH₃)₄] was synthesized. Crystal structures of [Rh₂(N-{2,4,6-CH₃}C₆H₂)COCH₃)₄]·2NCC₆H₅ and Ba_1.5[Fe(C₁₀H₁₃N₂O₇)][Co(CN)₆]·9H₂O were determined employing a Rigaku Mercury375R/M CCD (XtaLAB mini) diffractometer with graphite monochromated Mo-Kα radiation. For [Rh₂(N-{2,4,6-CH₃}C₆H₂)COCH₃)₄]·2NCC₆H₅, the space group was P-421c(#114) with unit cell dimensions: a =11.0169(14)Å, c =21.499(3)Å, V …

Synthetic, Spectroscopic And Dft Studies Of Iron Complexes With Iminobenzo(Semi)Quinone Ligands: Implications For O-Aminophenol Dioxygenases, Michael M. Bittner, David S. Krause, Sergey V. Lindeman, Cordina V. Popescu, Adam T. Fiedler

Chemistry Faculty Research and Publications

The oxidative CC bond cleavage of o-aminophenols by nonheme Fe dioxygenases is a critical step in both human metabolism (the kynurenine pathway) and the microbial degradation of nitroaromatic pollutants. The catalytic cycle of o-aminophenol dioxygenases (APDOs) has been proposed to involve formation of an Fe^II/O₂/iminobenzosemiquinone complex, although the presence of a substrate radical has been called into question by studies of related ring-cleaving dioxygenases. Recently, we reported the first synthesis of an iron(II) complex coordinated to an iminobenzosemiquinone (ISQ) ligand, namely, [Fe(Tp)(^tBuISQ)] (2 a; where Tp=hydrotris(3,5-diphenylpyrazol-1-yl)borate and ^{tBu …}

Identification Of An Active Site-Bound Nitrile Hydratase Intermediate Through Single Turnover Stopped-Flow Spectroscopy, Natalie Gumataotao, Misty L. Kuhn, Natalia Hajnas, Richard C. Holz

Chemistry Faculty Research and Publications

Stopped-flow kinetic data were obtained for the iron-type nitrile hydratase from Rhodococcus equi TG328-2 (ReNHase) using methacrylonitrile as the substrate. Multiple turnover experiments suggest a three-step kinetic model that allows for the reversible binding of substrate, the presence of an intermediate, and the formation of product. Microscopic rate constants determined from these data are in good agreement with steady state data confirming that the stopped-flow method used was appropriate for the reaction. Single turnover stopped-flow experiments were used to identify catalytic intermediates. These data were globally fit confirming a three-step kinetic model. Independent absorption spectra acquired between 0.005 …