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Articles 1 - 30 of 21992

Full-Text Articles in Chemistry

Palladium Complexes Bearing Κ²-N,N And Κ³-N,N,O Pendant Amine Bis(Phenolate) Ligands, Brendan J. Graziano, Eric M. Collins, Nathaniel C. Mccutcheon, Claire L. Griffith, Nicole M. Braunscheidel, Trilisa M. Perrine, Bradley M. Wile Jan 2019

Palladium Complexes Bearing Κ²-N,N And Κ³-N,N,O Pendant Amine Bis(Phenolate) Ligands, Brendan J. Graziano, Eric M. Collins, Nathaniel C. Mccutcheon, Claire L. Griffith, Nicole M. Braunscheidel, Trilisa M. Perrine, Bradley M. Wile

Chemistry Faculty Scholarship

The synthesis and characterization of ten new palladium(II) amine bis(phenolate) complexes is reported. Solution and single-crystal X-ray diffraction studies reveal the presence of both κ2-N,N and κ3-N,N,O binding modes in these square planar complexes. For complexes with sterically less demanding phenolate donors, addition of external acidic or basic reagents allows for the selective masking of a coordination site at Pd. Complexes bearing bulky cumyl substituents on phenolate donors exhibited unusual 1H NMR spectroscopic features that are consistent with an anagostic interaction with the palladium center. Computational analysis at the ωB97X-D ...


Computational Quantum Chemistry Studies Of The Interactions Of Amino Acids Side Chains With The Guanine Radical Cation., Edward Acheampong Dec 2018

Computational Quantum Chemistry Studies Of The Interactions Of Amino Acids Side Chains With The Guanine Radical Cation., Edward Acheampong

Electronic Theses and Dissertations

Guanine is generally accepted as the most easily oxidized DNA base when cells are subjected to ionizing radiation, photoionization or photosensitization. At pH 7, the midpoint reduction potential is on the order of 0.2 – 0.3 V higher than those of the radicals of e.g. tyrosine, tryptophan cysteine and histidine, so that the radical “repair” (or at least, a thermodynamically favorable reaction) involving these amino acids is feasible. Computational quantum studies have been done on tyrosine, tryptophan, cysteine and histidine side chains as they appear in histones. Density functional theory was employed using B3LYP/6-31G+ (d, p) basis ...


Synthesis Of Dicamba Glucosides For The Study Of Environmental Dicamba Drift Effects On Soybeans, Holly Wallace Dec 2018

Synthesis Of Dicamba Glucosides For The Study Of Environmental Dicamba Drift Effects On Soybeans, Holly Wallace

Theses and Dissertations

The most popular herbicide used for weed control has been glyphosate for many years in the Midwestern United States. Plants have begun to develop a resistance to glyphosate due to over use of the herbicide. This herbicide resistance has pushed farmers to turn to alternative herbicides such as dicamba and 2,4-D. Recently agrochemical companies have developed genetically modified crops that are resistant to herbicides such as dicamba. These modified crops allow farmers to spray their fields with dicamba without fear of crop damage. Farmers of non-genetically modified crops, however, suffer damage and loss of yield from herbicide drift effects ...


Quantum Mechanical Studies Of N-H···N Hydrogen Bonding In Acetamide Derivatives And Amino Acids, Sandra J. Lundell Dec 2018

Quantum Mechanical Studies Of N-H···N Hydrogen Bonding In Acetamide Derivatives And Amino Acids, Sandra J. Lundell

All Graduate Theses and Dissertations

Proteins are made of vast chains of amino acids that twist and fold into intricate designs. These structures are held in place by networks of noncovalent interactions. One of these, the hydrogen bond, forms bridges between adjacent pieces of the protein chain and is one of the most important contributors to the shape and stability of proteins. Hydrogen bonds come in all shapes and sizes and a full understanding of these not only aids in our understanding of proteins in general but can bridge the gap to finding cures to many protein-related diseases, such as sickle-cell anemia. The primary aim ...


Ray Et Al.: Pheromone Of The Velvet Longhorned Beetle Trichoferus Campestris, Ann M. Ray, Joseph A. Francese, Yunfan Zou, Kristopher Watson, Damon J. Crook, Jocelyn G. Millar Dec 2018

Ray Et Al.: Pheromone Of The Velvet Longhorned Beetle Trichoferus Campestris, Ann M. Ray, Joseph A. Francese, Yunfan Zou, Kristopher Watson, Damon J. Crook, Jocelyn G. Millar

Faculty Scholarship

No abstract provided.


A Near-Infrared Fluorescent Probe Based On A Fret Rhodamine Donor Linked To A Cyanine Acceptor For Sensitive Detection Of Intracellular Ph Alternations, Yibin Zhang, Jianheng Bi, Shuai Xia, Wafa Mazi, Shulin Wan, Logan Mikesell, Rudy Luck, Haiying Liu Oct 2018

A Near-Infrared Fluorescent Probe Based On A Fret Rhodamine Donor Linked To A Cyanine Acceptor For Sensitive Detection Of Intracellular Ph Alternations, Yibin Zhang, Jianheng Bi, Shuai Xia, Wafa Mazi, Shulin Wan, Logan Mikesell, Rudy Luck, Haiying Liu

Department of Chemistry Publications

A fluorescence resonance energy transfer (FRET)-based near-infrared fluorescent probe (B+) for double-checked sensitive detection of intracellular pH changes has been synthesized by binding a near-infrared rhodamine donor to a near-infrared cyanine acceptor through robust C-N bonds via a nucleophilic substitution reaction. To demonstrate the double-checked advantages of probe B+, a near-infrared probe (A) was also prepared by modification of a near-infrared rhodamine dye with ethylenediamine to produce a closed spirolactam residue. Under basic conditions, probe B+ shows only weak fluorescence from the cyanine acceptor while probe A displays nonfluorescence due to retention of the closed spirolactam form of the ...


Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman Oct 2018

Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman

Chemistry Faculty Publications

Heterogeneous photocatalysis is a prominent area of research with major applications in solar energy conversion, air pollution mitigation, and removal of contaminants from water. A large number of scientific papers related to the photocatalysis field and its environmental applications are published in different journals specializing in materials and nanomaterials. However, many problems exist in the conception of papers by authors unfamiliar with standard characterization methods of photocatalysts as well as with the procedures needed to determine photocatalytic activities based on the determination of “apparent quantum efficiencies” within a wavelength interval or “apparent quantum yields” in the case of using monochromatic ...


Textured Nise₂ Film: Bifunctional Electrocatalyst For Full Water Splitting At Remarkably Low Overpotential With High Energy Efficiency, Abdurazag T. Swesi, Jahangir Masud, Wipula P. R. Liyanage, Siddesh Umapathi, Eric W. Bohannan, Julia E. Medvedeva, Manashi Nath Oct 2018

Textured Nise₂ Film: Bifunctional Electrocatalyst For Full Water Splitting At Remarkably Low Overpotential With High Energy Efficiency, Abdurazag T. Swesi, Jahangir Masud, Wipula P. R. Liyanage, Siddesh Umapathi, Eric W. Bohannan, Julia E. Medvedeva, Manashi Nath

Julia E. Medvedeva

Herein we have shown that electrodeposited NiSe2 can be used as a bifunctional electrocatalyst under alkaline conditions to split water at very low potential by catalyzing both oxygen evolution and hydrogen evolution reactions at anode and cathode, respectively, achieving a very high electrolysis energy efficiency exceeding 80% at considerably high current densities (100 mA cm-2). The OER catalytic activity as well as electrolysis energy efficiency surpasses any previously reported OER electrocatalyst in alkaline medium and energy efficiency of an electrolyzer using state-of-the-art Pt and RuO2 as the HER and OER catalyst, respectively. Through detailed electrochemical and structural ...


Flexible Laser-Induced Graphene For Nitrogen Sensing In Soil, Nate T. Garland, Eric S. Mclamore, Nicholas D. Cavallaro, Deyny Mendivelso-Perez, Emily A. Smith, Dapeng Jing, Jonathan C. Claussen Oct 2018

Flexible Laser-Induced Graphene For Nitrogen Sensing In Soil, Nate T. Garland, Eric S. Mclamore, Nicholas D. Cavallaro, Deyny Mendivelso-Perez, Emily A. Smith, Dapeng Jing, Jonathan C. Claussen

Mechanical Engineering Publications

Flexible graphene electronics are rapidly gaining interest, but their widespread implementation has been impeded by challenges with ink preparation, ink printing, and post-print annealing processes. Laser-induced graphene (LIG) promises a facile alternative by creating flexible graphene electronics on polyimide substrates through a one-step laser writing fabrication method. Herein we demonstrate the use of LIG, created through a low-cost UV laser, for electrochemical ion selective sensing of plant-available nitrogen (i.e., both ammonium and nitrate ions: NH4+ and NO3-) in soil samples. The laser used to create the LIG was operated at distinct pulse rates (10, 20, 30, 40, and 50 ...


Molecular And Physical Characteristics Of Aerosol At A Remote Free Troposphere Site: Implications For Atmospheric Aging, Simeon Schum, Bo Zhang, Katja Džepina, Paolo Fialho, Claudio Mazzoleni, Lynn Mazzoleni Oct 2018

Molecular And Physical Characteristics Of Aerosol At A Remote Free Troposphere Site: Implications For Atmospheric Aging, Simeon Schum, Bo Zhang, Katja Džepina, Paolo Fialho, Claudio Mazzoleni, Lynn Mazzoleni

Department of Chemistry Publications

Aerosol properties are transformed by atmospheric processes during long-range transport and play a key role in the Earth's radiative balance. To understand the molecular and physical characteristics of free tropospheric aerosol, we studied samples collected at the Pico Mountain Observatory in the North Atlantic. The observatory is located in the marine free troposphere at 2225m above sea level, on Pico Island in the Azores archipelago. The site is ideal for the study of long-range-transported free tropospheric aerosol with minimal local influence. Three aerosol samples with elevated organic carbon concentrations were selected for detailed analysis. FLEXPART retroplumes indicated that two ...


Thermochemistry: Heat Of Neutralization And Hess’S Law [Chemistry], Kevin Mark, Phil Mercier, Janet Gonzalez, Burl Yearwood Oct 2018

Thermochemistry: Heat Of Neutralization And Hess’S Law [Chemistry], Kevin Mark, Phil Mercier, Janet Gonzalez, Burl Yearwood

Open Educational Resources

The General Chemistry 1 (SCC 201) course has been designated for the core competency of Inquiry and Problem Solving along with the Written Communication Ability. These abilities are best observed in the laboratory section of the course where SCC 201 students are asked to submit weekly written lab reports that range in chemistry topics from chemical structures to the chemical analysis of polluted environments. SCC 201 will be implementing a new experiment in the laboratory portion of the course entitled, “Thermochemistry: Heat of Neutralization and Hess’s Law.” The design of the experiment incorporates many elements of LaGCC’s Core ...


Microwave Reflectometry As A Novel Diagnostic Tool For Detection Of Skin Cancers, Pratik Mehta, Kundan Chand, Deepak Narayanswamy, Daryl G. Beetner, R. Zoughi, William V. Stoecker Sep 2018

Microwave Reflectometry As A Novel Diagnostic Tool For Detection Of Skin Cancers, Pratik Mehta, Kundan Chand, Deepak Narayanswamy, Daryl G. Beetner, R. Zoughi, William V. Stoecker

Reza Zoughi

More than 1 000 000 people are diagnosed with skin cancer each year in the United States, and more than 10 000 people die from the disease. Methods such as visual inspection and dermoscopy are available for early detection of skin cancers, but improvement in accuracy is needed. This paper investigates the use of microwave reflectometry as a potential diagnostic tool for detection of skin cancers. Open-ended coaxial probes were used to measure microwave properties of skin. The influences of measurement parameters such as probe application pressure, power level, and variation in reflection properties of skin with location and hydration ...


Bdpa-Nitroxide Biradicals Tailored For Efficient Dynamic Nuclear Polarization Enhanced Solid-State Nmr At Magnetic Fields Up To 21.1 T, Dorothea Wisser, Ganesan Karthikeyan, Alicia Lund, Gilles Casano, Hakim Karoui, Maxim Yulikov, Georges Menzildjian, Arthur C. Pinon, Armin Purea, Frank Engelke, Sachin R. Chaudhari, Dominik Kubicki, Aaron Rossini, Ilia B. Moroz, David Gajan, Christophe Copéret, Gunnar Jeschke, Moreno Lelli, Lyndon Emsley, Anne Lesage, Olivier Ouari Sep 2018

Bdpa-Nitroxide Biradicals Tailored For Efficient Dynamic Nuclear Polarization Enhanced Solid-State Nmr At Magnetic Fields Up To 21.1 T, Dorothea Wisser, Ganesan Karthikeyan, Alicia Lund, Gilles Casano, Hakim Karoui, Maxim Yulikov, Georges Menzildjian, Arthur C. Pinon, Armin Purea, Frank Engelke, Sachin R. Chaudhari, Dominik Kubicki, Aaron Rossini, Ilia B. Moroz, David Gajan, Christophe Copéret, Gunnar Jeschke, Moreno Lelli, Lyndon Emsley, Anne Lesage, Olivier Ouari

Chemistry Publications

Dynamic Nuclear Polarization (DNP) solid-state NMR has developed into an invaluable tool for the investigation of a wide range of materials. However, the sensitivity gain achieved with many polarizing agents suffers from an unfavorable field and Magic Angle Spinning (MAS) frequency dependence. We present a series of new hybrid biradicals, soluble in organic solvents, that consist of an isotropic narrow EPR line radical, BDPA, tethered to a broad line nitroxide. By tuning the distance between the two electrons and the substituents at the nitroxide moiety, correlations between the electron-electron interactions and the electronic spin relaxation times on one hand, and ...


Efforts Towards The Discovery Of Novel Methods For The Synthesis Of Pharmacologically Relevant Molecular Scaffolds, Graham Joseph Haun Sep 2018

Efforts Towards The Discovery Of Novel Methods For The Synthesis Of Pharmacologically Relevant Molecular Scaffolds, Graham Joseph Haun

Theses and Dissertations

With the introductions of pharmaceuticals into modern day society many people have been using them to improve their lives. Due to this high increase in demand along with the ever-growing concern of environmental impact pharmaceutical companies have been pressed to synthesis new and existing drugs at a higher rate. This increased rate can cause low yield drugs or have a heavy environmental impact. As the use of pharmaceuticals becomes more widespread the need for greener and simpler organic synthesis methods to make these pharmaceuticals becomes more needed.

Herein is reported the methodological development of different pharmacologically relevant scaffolds. This work ...


Hydrogen-Deuterium Exchange Mass Spectrometry And Molecular Dynamics Simulations For Studying Protein Structure And Dynamics, Yiming Xiao Sep 2018

Hydrogen-Deuterium Exchange Mass Spectrometry And Molecular Dynamics Simulations For Studying Protein Structure And Dynamics, Yiming Xiao

Electronic Thesis and Dissertation Repository

Deciphering properties of proteins are essential for human health and aiding in the development of new pharmaceuticals. This dissertation uses hydrogen-deuterium exchange (HDX) mass spectrometry (MS) and molecular dynamics (MD) simulations to study protein dynamics, for improving the understanding of protein folding/unfolding mechanisms, and ligand binding and allosteric regulation.

Chapter 2 uses HDX-MS for probing the conformational dynamics of myoglobin in the presence of N2 bubbles. We propose a dynamic model that reproduces the observed data: “semi-unfolded” “native” “globally unfolded” -> “aggregated”. Chapter 3 focuses on osteoprotegerin (OPG), which hinders bone resorption by inhibiting RANK/RANKL interactions. The dimerization ...


Mechanism Of Protein Charging And Supercharging In Electrospray Ionization: Molecular Dynamics Simulations And Experimental Investigations, Haidy S. Metwally Sep 2018

Mechanism Of Protein Charging And Supercharging In Electrospray Ionization: Molecular Dynamics Simulations And Experimental Investigations, Haidy S. Metwally

Electronic Thesis and Dissertation Repository

Electrospray ionization mass spectrometry (ESI-MS) is a powerful technique for investigating protein structures, conformations, and interactions. Despite its widespread use, many fundamental aspects of ESI remain poorly understood. In this thesis, we use a combination of molecular dynamics (MD) simulations and experiments to gain insights into the hidden complexities of ESI-MS.

Chapter 2 discusses the topic of salt-induced protein signal degradation. Salts such as NaCl, CsCl, and tetrabutyl ammonium chloride (NBu4Cl) interfere with MS data acquisition, leading to adduct formation and signal suppression. MD simulations provide an explanation for these salt interferences. Signal suppression can be broken down ...


Sensitivity-Enhanced 207pb Solid-State Nmr Spectroscopy For The Rapid, Non-Destructive Characterization Of Organolead Halide Perovskites, Michael P. Hanrahan, Long Men, Bryan A. Rosales, Javier Vela, Aaron J. Rossini Sep 2018

Sensitivity-Enhanced 207pb Solid-State Nmr Spectroscopy For The Rapid, Non-Destructive Characterization Of Organolead Halide Perovskites, Michael P. Hanrahan, Long Men, Bryan A. Rosales, Javier Vela, Aaron J. Rossini

Chemistry Publications

Organolead halide and mixed halide perovskites (CH3NH3PbX3, CH3NH3PbX3–nYn, X and Y = Cl–, Br– or I–), are promising materials for photovoltaics and optoelectronic devices. 207Pb solid-state NMR spectroscopy has previously been applied to characterize phase segregation and halide ion speciation in mixed halide perovskites. However, NMR spectroscopy is an insensitive technique that often requires large sample volumes and long signal averaging periods. This is especially true for mixed halide perovskites, which give rise to extremely broad 207Pb solid-state NMR spectra. Here, we quantitatively compare the sensitivity of the various solid-state NMR techniques on pure and mixed halide organolead perovskites and ...


Molecular Insights On Aging And Aqueous-Phase Processing From Ambient Biomass Burning Emissions-Influenced Po Valley Fog And Aerosol, Matthew Brege, Marco Paglione, Stefania Gilardoni, Maria Cristina Facchini, Lynn Mazzoleni Sep 2018

Molecular Insights On Aging And Aqueous-Phase Processing From Ambient Biomass Burning Emissions-Influenced Po Valley Fog And Aerosol, Matthew Brege, Marco Paglione, Stefania Gilardoni, Maria Cristina Facchini, Lynn Mazzoleni

Department of Chemistry Publications

To study the influence of regional biomass burning emissions and secondary processes, ambient samples of fog and aerosol were collected in the Po Valley (Italy) during the 2013 Supersito field campaign. After the extent of fresh vs. aged biomass burning influence was estimated from proton nuclear magnetic resonance (1H NMR) and high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS), two samples of fog water and two samples of PM1 aerosol were selected for ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis. Molecular compositions indicated that the water-soluble organic matter was largely non-polymeric without clearly repeating units. The selected ...


How To Fold And Protect Mitochondrial Ribosomal Rna With Fewer Guanines, Maryam Hosseini, Poorna Roy, Marie Sissler, Craig L. Zirbel, Eric Westhof, Neocles B. Leontis Sep 2018

How To Fold And Protect Mitochondrial Ribosomal Rna With Fewer Guanines, Maryam Hosseini, Poorna Roy, Marie Sissler, Craig L. Zirbel, Eric Westhof, Neocles B. Leontis

Chemistry Faculty Publications

Mammalian mitochondrial ribosomes evolved from bacterial ribosomes by reduction of ribosomal RNAs, increase of ribosomal protein content, and loss of guanine nucleotides. Guanine is the base most sensitive to oxidative damage. By systematically comparing high-quality, small ribosomal subunit RNA sequence alignments and solved 3D ribosome structures from mammalian mitochondria and bacteria, we deduce rules for folding a complex RNA with the remaining guanines shielded from solvent. Almost all conserved guanines in both bacterial and mammalian mitochondrial ribosomal RNA form guaninespecific, local or long-range, RNA–RNA or RNA– protein interactions. Many solvent-exposed guanines conserved in bacteria are replaced in mammalian mitochondria ...


Unraveling The Stereodynamics Of Cold Controlled Hd−H2 Collisions, James F. E. Croft, Naduvalath Balakrishnan, Meng Huang, Hua Guo Sep 2018

Unraveling The Stereodynamics Of Cold Controlled Hd−H2 Collisions, James F. E. Croft, Naduvalath Balakrishnan, Meng Huang, Hua Guo

Chemistry and Biochemistry Faculty Publications

Measuring inelastic rates with partial-wave resolution requires temperatures close to a Kelvin or below, even for the lightest molecule. In a recent experiment, Perreault, Mukherjee, and Zare [Nat. Chem. 10, 561 (2018).] studied collisional relaxation of excited HD molecules in the v=1, j=2 state by para- and ortho-H2 at a temperature of about 1 K, extracting the angular distribution of scattered HD in the v=1, j=0 state. By state preparation of the HD molecules, control of the angular distribution of scattered HD was demonstrated. Here, we report a first-principles simulation of that experiment which enables us ...


An Overview Of Dynamic Heterogeneous Oxidations In The Troposphere, Elizabeth A. Pillar-Little, Marcelo I. Guzman Sep 2018

An Overview Of Dynamic Heterogeneous Oxidations In The Troposphere, Elizabeth A. Pillar-Little, Marcelo I. Guzman

Chemistry Faculty Publications

Due to the adverse effect of atmospheric aerosols on public health and their ability to affect climate, extensive research has been undertaken in recent decades to understand their sources and sinks, as well as to study their physical and chemical properties. Atmospheric aerosols are important players in the Earth’s radiative budget, affecting incoming and outgoing solar radiation through absorption and scattering by direct and indirect means. While the cooling properties of pure inorganic aerosols are relatively well understood, the impact of organic aerosols on the radiative budget is unclear. Additionally, organic aerosols are transformed through chemical reactions during atmospheric ...


Illuminating Biology With Membrane Penetrating Sulfonate Delivery Scaffolds And Near-Infrared Azasiline Fluorophores, Adam Choi Sep 2018

Illuminating Biology With Membrane Penetrating Sulfonate Delivery Scaffolds And Near-Infrared Azasiline Fluorophores, Adam Choi

GSBS Dissertations and Theses

Near-infrared (NIR) light, with wavelengths of 650 to 900 nanometers, effectively penetrates tissues. The high signal to noise ratio and low phototoxicity of NIR light makes this wavelength range ideal for deep tissue imaging. However, current NIR fluorophores are generally large hydrophobic molecules that are prone to aggregation. Sulfonation can enhance aqueous solubility, but their anionic nature prevents membrane diffusion, and thus, restricts the applications of sulfonated molecules to in vitro or fixed cells.

The repertoire of commercially available sulfonated NIR probes is mostly limited cyanines, which have low photostability. Moreover, larger cyanines require multiple sulfonates to maintain aqueous solubility ...


Enhancement Of Triplet-Sensitized Upconversion In Rigid Polymers Via Singlet Exciton Sink Approach, Steponas Raišys, Saulius Juršėnas, Yoan C. Simon, Christoph Weder, Karolis Kazlauskas Sep 2018

Enhancement Of Triplet-Sensitized Upconversion In Rigid Polymers Via Singlet Exciton Sink Approach, Steponas Raišys, Saulius Juršėnas, Yoan C. Simon, Christoph Weder, Karolis Kazlauskas

Faculty Publications

To increase the practical usefulness of solid-state sensitized upconversion (UC) materials as components of solar energy harvesting systems, it is important to identify and suppress loss mechanisms, and increase the UC quantum yield (ΦUC). Here we focus on a benchmark UC system consisting of the emitter 9,10-diphenylanthracene (DPA) and the sensitizer platinum octaethylporphyrin (PtOEP) in a rigid poly(methyl methacrylate) (PMMA) matrix, and show that one of the major losses originates from Förster resonant energy transfer (FRET) from DPA back to PtOEP. Even though DPA emission lies within the PtOEP transparency window, the quantitative assessment of singlet exciton ...


Archean Phosphorus Liberation Induced By Iron Redox Geochemistry, Barry Herschy, Sae Jung Chang, Ruth Blake, Aivo Lepland, Heather Abbott-Lyon, Jacqueline Sampson, Zachary Atlas, Terence P. Kee, Matthew A. Pasek Sep 2018

Archean Phosphorus Liberation Induced By Iron Redox Geochemistry, Barry Herschy, Sae Jung Chang, Ruth Blake, Aivo Lepland, Heather Abbott-Lyon, Jacqueline Sampson, Zachary Atlas, Terence P. Kee, Matthew A. Pasek

Faculty Publications

The element phosphorus (P) is central to ecosystem growth and is proposed to be a limiting nutrient for life. The Archean ocean may have been strongly phosphorus-limited due to the selective binding of phosphate to iron oxyhydroxide. Here we report a new route to solubilizing phosphorus in the ancient oceans: reduction of phosphate to phosphite by iron(II) at low (<200 >°C) diagenetic temperatures. Reduction of phosphate to phosphite was likely widespread in the Archean, as the reaction occurs rapidly and is demonstrated from thermochemical modeling, experimental analogs, and detection of phosphite in early Archean rocks. We further demonstrate that the ...


Crystal Structure Of A Homoleptic Zinc(Ii) Complex Based On Bis­(3,5-Diiso­Propyl­Pyrazol-1-Yl)Acetate, Josiah G. Elsberg, Nicholas G. Spiropulos, Adam C. Colson, Eric C. Brown Sep 2018

Crystal Structure Of A Homoleptic Zinc(Ii) Complex Based On Bis­(3,5-Diiso­Propyl­Pyrazol-1-Yl)Acetate, Josiah G. Elsberg, Nicholas G. Spiropulos, Adam C. Colson, Eric C. Brown

Chemistry Faculty Publications and Presentations

Deprotonation of the methyl­ene group in bis­(3,5-diiso­propyl­pyrazol-1-yl)methane with nBuLi and reaction with carbon dioxide yields lithium bis­(3,5-diiso­propyl­pyrazol-1-yl)acetate (1). Treatment of 1 with ZnCl2 results in the com­pound bis­[bis­(3,5-diiso­propyl­pyrazol-1-yl)acetato]­zinc(II), [Zn(C20H31N4O2)2] (2), whose structure has monoclinic (P21/c) symmetry. The ZnII ion resides on an inversion center and is coordinated by two bis­(3,5-diiso­propyl­pyrazol-1-yl)acetate (bdippza) ligands. Each ligand facially coordinates the zinc center via ...


Nmr Characterizations Of Candidate Battery Electrolytes, Stephen A. Munoz Sep 2018

Nmr Characterizations Of Candidate Battery Electrolytes, Stephen A. Munoz

All Dissertations, Theses, and Capstone Projects

Enormous strides have been made in next-generation power sources to build a more sustainable society. Energy storage has become a limiting factor in our progress, and there are huge environmental and financial incentives to find the next step forward in battery technology. This work discusses NMR methods for characterizing materials for use in battery application, with a special focus on relaxometry and diffusometry. Examples are provided of various recent investigations involving novel candidate electrolyte materials with different collaborators. Works discussed in this thesis include: the characterization of a new disruptive solid polymer electrolyte technology, investigations of the dynamics of super ...


Fundamental Chemistry Related To The Separations And Coordination Of Actinium-225, Thorium-227, And Technetium-99, Jasmine L. Hatcher Sep 2018

Fundamental Chemistry Related To The Separations And Coordination Of Actinium-225, Thorium-227, And Technetium-99, Jasmine L. Hatcher

All Dissertations, Theses, and Capstone Projects

This work explores the fundamental chemistry of actinium, thorium, and technetium in an effort to develop methodologies which help to address complications specific to each of these elements. Developing fundamental knowledge in inorganic chemistry has the power to meaningfully address a number of real world problems. By using simple systems and experiments like following an electron or changing the solvent system, we are able to gain invaluable information which can be used to address major issues.

Actinium-225 (t½: 9.92 d) is an alpha-emitting radionuclide with nuclear properties well suited for alpha therapy of malignant tumors. The present global ...


Nuclear Magnetic Resonance Studies Of Imidazolium-Based Ionic Liquids And Garnet-Type Li7la3zr2o12, Shen Lai Sep 2018

Nuclear Magnetic Resonance Studies Of Imidazolium-Based Ionic Liquids And Garnet-Type Li7la3zr2o12, Shen Lai

All Dissertations, Theses, and Capstone Projects

Advancements in electrochemical energy storage materials are critical in the development and utilization of renewable energy technologies. These advancements involve obtaining a better understanding of electrochemical mechanisms and properties through scientific research towards an improved energy storage technology. Nuclear magnetic resonance (NMR), is a sensitive and selective method to probe particle dynamics (magnetic relaxation, diffusometry, etc.) and material structures (spectroscopy) down to the atomic level. In this work, several NMR techniques are employed to study imidazolium-based ionic liquids and garnet-type inorganic materials. These are being studied due to their potential use as safer alternatives to organic solvent-based electrolytes in lithium-ion ...


Flexible And Versatile Soft Templates For Mesoporous Silicas And Organosilicas Based On Pluronic Block Copolymer Surfactants And Their Mixtures, George Farid Sep 2018

Flexible And Versatile Soft Templates For Mesoporous Silicas And Organosilicas Based On Pluronic Block Copolymer Surfactants And Their Mixtures, George Farid

All Dissertations, Theses, and Capstone Projects

In this dissertation, the work will be discussed that was focused on the synthesis of consolidated periodic mesoporous materials such as 2-D hexgonal ordered mesoporous silicas (SBA-15) as well as single-micelle-templated silica and organosilica nanotubes and nanospheres using triblock copolymer surfactants and their mixtures in the presence of a swelling agent. The introductory section, Chapter 1, will address the current state of the tunability of single-micelle-templated silica and organosilica nanotubes and will compare it with the work presented in this dissertation on the use of a dual-surfactant templating systems. Chapter 2 of the dissertation discusses transmission electron microscopy characterization of ...


Nascent O2 (A1ΔG, V = 0, 1) Rotational Distributions From The Photodissociation Of Jet‐Cooled O3 In The Hartley Band, Michelle L. Warter, Carolyn E. Gunthardt, Wei Wei, George Mcbane, Simon W. North Sep 2018

Nascent O2 (A1ΔG, V = 0, 1) Rotational Distributions From The Photodissociation Of Jet‐Cooled O3 In The Hartley Band, Michelle L. Warter, Carolyn E. Gunthardt, Wei Wei, George Mcbane, Simon W. North

Peer Reviewed Articles

We report rotational distributions for the O2 (a 1Δg) fragment from photodissociation of jet‐cooled O3 at 248, 266, and 282 nm. The rotational distributions show a population alternation that favors the even states, as previously reported for a 300 K sample by Valentini et al. (J. Chem. Phys. 86, 6745 (1987)). The alternation from the jet‐cooled precursor is much stronger than that observed by Valentini et al., and in contrast to their observations does not depend strongly on O2 (a 1Δg) vibrational state or photolysis wavelength. The odd/even alternation diminishes ...