Chemistry Commons^™

Aluminum Catalysts In The Ring-Opening Polymerizations Of Cyclic Esters, Appie A. Peterson

Arts & Sciences Graduate Student Theses and Dissertations

The development of bioderived and biodegradable materials is crucial in supplanting our global dependence on fossil fuel derived plastics. An industrially attractive method for synthesizing such polymers is the ring-opening polymerization (ROP) of cyclic monomers sourced from biomass feedstocks. Cyclic esters such as rac-lactide and ε-caprolactone are known to produce aliphatic polyesters via ROP catalyzed by metal alkoxides. The work described herein centers on single-site Aluminum catalysts, which are well-suited for mechanistic studies of ROP due to their convenient rates, production of high molecular weight polymers, and low toxicities. By modulating the steric and electronic substituents of the ligand system, …

A Systematic Approach For Developing Feed-Forward/Back-Propagating Neural Network Models For Predicting Bulk Chemical And Physical Properties Of Transition Metals, Neil Clifton Mitchell

Theses and Dissertations

Bulk materials made from transition elements and their alloys are substances used in many industrial applications and are composed of elements contained in the d- and f-blocks of the periodic table. Many of the useful properties of these materials are related to their unfilled d- and f-orbitals. It is supposed that computational models of orbitals describing two-atom homogeneous clusters of transition elements provide enough information to predict bulk chemical and physical properties of transition materials. This thesis reports the use of a simple (one hidden node) three layer feed-forward/back-propagating artificial neural network and orbital energies obtained from DFT-SCF/MO approximations to …

Residue–Residue Contact Changes During Functional Processes Define Allosteric Communication Pathways, Xin-Qiu Joe Yao, Donald Hamelberg

Chemistry Faculty Publications

Allosteric regulation plays a central role in orchestrating diverse cellular processes. A prerequisite for allostery is a flexible biomolecule within which two distal sites can communicate via concerted or sequential conformational changes. We introduce a computational method to elucidate allosteric communication pathways, comprising critical allosteric residues, in biomolecules by taking advantage of conformational changes during a functional process. Conformational changes are modeled explicitly since they modulate the network of residue–residue interactions, which could propagate allosteric signals between two or more distal sites. The method implements the suboptimal path analysis in the framework of the difference contact network analysis or dCNA. …

Directions For The Development Of Personal Subsidiary Farms And Increasing Sources Of Income In The Future, Yakupov Kabil

Karakalpak Scientific Journal

This article discusses the features of the development of personal subsidiary farms in modern conditions, defines their functions in the agrarian economy and in the life of society as a whole. Modern agrarian policy provides for the development of various forms of management, including personal subsidiary farms. Personal subsidiary farms are an organic part of the agricultural sectors and make a significant contribution to solving the food problem of the country. The provision of the population with food products is carried out by personal subsidiary farms through their own consumption, as well as the sale of surplus products.

Near-Infrared Unsymmetrical Squaraine Core-Based Sensitizers For Co-Sensitized High-Photocurrent Dye-Sensitized Solar Cells, Jonathon Watson, Roberta R. Rodrigues, Jared H. Delcamp

Faculty and Student Publications

Increased conversion of near-infrared (NIR) photons to electricity is needed to improve dye-sensitized solar cells (DSCs). Here, we report two squaraine dyes (RR13 and RR14) with unsymmetrical cores as NIR dyes in DSCs. Both dyes feature a conjugated indolizine donor with an indoline donor on the opposite side of the squaraine core. The dyes are studied via absorption spectroscopy, computational interrogation, and electrochemical analysis. The use of the strongly donating indolizine donor results in NIR photon-to-current conversion extending beyond 800 nm on TiO2 in DSC devices. The DSC devices were characterized by current-voltage curves, incident photon-to-current conversion efficiency measurements, and …

Indole-3-Glycerol Phosphate Synthase From Mycobacterium Tuberculosis: A Potential New Drug Target, Nikolas Esposito, David W. Konas, Nina M. Goodey

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

Tuberculosis (TB), caused by the pathogen Mycobacterium tuberculosis, affects millions of people worldwide. Several TB drugs have lost efficacy due to emerging drug resistance and new anti-TB targets are needed. Recent research suggests that indole-3-glycerol phosphate synthase (IGPS) in M. tuberculosis (MtIGPS) could be such a target. IGPS is a (β/α)8-barrel enzyme that catalyzes the conversion of 1-(o-carboxyphenylamino)-1-deoxyribulose 5’-phosphate (CdRP) into indole-glycerol-phosphate (IGP) in the bacterial tryptophan biosynthetic pathway. M. tuberculosis over expresses the tryptophan pathway genes during an immune response and inhibition of MtIGPS allows CD4 T-cells to more effectively fight against M. tuberculosis. Here we review the published …

Spectroscopic Properties Relevant To Astronomical And Laboratory Detection Of Mch And Mch+ (M = Al, Mg), Vincent J. Esposito, Tarek Trabelsi, Joseph S. Francisco

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

New spectroscopic parameters have been calculated to aid in the laboratory and observational detection of AlCH, AlCH⁺, MgCH, MgCH⁺, and their deuterated analogs. All species exist in linear geometry except for AlCH+, which exhibits a bent structure. Rotational frequencies have been calculated and the transition with maximum intensity is discussed for three temperature regions present in space: 100 K for a central circumstellar envelope (CSE), 30 K for an outer CSE, and 3 K indicative of the interstellar medium. Pertinent frequencies range from 25 to 250 GHz, depending on the species. At 30 K, the most …

Flexible Bielectrode-Based Highly Sensitive Triboelectric Motion Sensor: A Sustainable And Smart Electronic Material, Damian Zamora, Abu Masa Abdullah, Alejandro Flores, Haimanti Majumder, Muhtasim Ul Karim Sadaf, Bahareh Azimi, Serena Danti, M. Jasim Uddin

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

The self-powered and autonomous sensors are incredibly important in advanced engineering, especially defence science. The increasing necessity of simple and smart electronics requires to be sustainably flexible, wearable, and waterproof. Triboelectricity has been a widely used mechanism for motion sensing nowadays. Almost all devices based on triboelectricity require contact between two surfaces. Herein, a touchless triboelectric motion sensor for human motion sensing and movement monitoring is developed. The device was primarily fabricated using simple latex (cis-1,4-polyisoprene) structures and copper (electrode materials), which make it a very cost-effective device for sensory applications. The device is tested with specimens of different areas …

Materials And Methodologies For Spectroscopic And Optical Analytical Applications In Cultural Heritage Conservation Science, Lyndsay Nichole Kissell

Dissertations and Theses

The field of conservation science falls in the intersection of science and art. The work of conservation scientists may include any single subdiscipline of chemistry, though it is most commonly a highly interdisciplinary field taking skills from analytical, organic, and inorganic chemistry, as well as surface and materials science. The aims of conservation scientists are to answer questions about the production and aging of material cultural heritage. Knowing the materials used by an artist can lead to insight about the intentions of the object and knowing how those materials degrade will enable the use of preventative measures to ensure the …

Synthesis And Biosynthesis Of 3-Hydroxy-Β-Lactam Antibiotics, Wei Wei

Arts & Sciences Graduate Student Theses and Dissertations

Novel treatments for tuberculosis (TB) are urgently needed to conquer this global health crisis. Unlike canonical β-lactam antibiotics that target transpeptidases by hydrolyzing the lactam ring, tabtoxinine-β-lactam (TβL) functions as a potent glutamine synthetase (GS) inhibitor by forming a transition state mimic. TβL has the potential to be used as an anti-TB agent by targeting the nitrogen metabolic pathway of pathogenic mycobacteria. This work reported an innovative, convergent, and flexible cross-metathesis method to obtain the fully protected TβL scaffold. The trans-olefin intermediate provides possibilities for synthesizing various derivatives through alkene functionalization reactions. We also developed and optimized a solid phase …

Methanol Decomposition On Ni(111) And O/Ni(111), Henrik Öström, Bingjie Zhang, Tiffany Vallejo, Bryn Merrill, Jeremy Huang, Jerry Larue

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Methanol decomposition on Ni(111) surfaces has been studied in the presence and absence of oxygen using temperature-programmed desorption and temperature-dependent sum frequency generation spectroscopy. Under both conditions the C–H and O–H bonds break, forming carbon monoxide and atomic hydrogen on the surface. No C–O bond scission was observed, limiting the number of reaction pathways. The O–H bonds break first (>150 K), forming surface methoxy, followed by C–H bond breakage (>250 K). All atomic hydrogen desorbs from the surface as H2 through H+H recombinative desorption. H2 desorbs at a higher temperature in the presence of oxygen (>300 K) …

Diamond And Methane Formation From The Chemical Decomposition Of Polyethylene At High Pressures And Temperatures, E. B. Watkins, R. C. Huber, C. M. Childs, Ashkan Salamat, J. S. Pigott, P. Chow, Y. Xiao, J. D. Coe

Physics & Astronomy Faculty Research

Polyethylene (C2H4)n was compressed to pressures between 10 and 30 GPa in a diamond anvil cell (DAC) and laser heated above 2500 K for approximately one second. This resulted in the chemical decomposition of the polymer into carbon and hydrocarbon reaction products. After quenching to ambient temperature, the decomposition products were measured in the DAC at pressures ranging from ambient to 29 GPa using a combination of x-ray diffraction (XRD) and small angle x-ray scattering (SAXS). XRD identified cubic diamond and methane as the predominant product species with their pressure–volume relationships exhibiting strong correlations to the diamond and methane equations …

One-Pot Conversion Of Carboxylic Acids To Aldehydes, Hannah Khan, Michael Nantz, Saurin Sutaria

Posters-at-the-Capitol

There are many different ways to convert a carboxylic text acid to an aldehyde. A common way to accomplish this transformation is to use multiple steps (e.g., reduction of the carboxylic acid to the corresponding alcohol followed by selective oxidation to the aldehyde). Our success in reducing the diacid muconic acid (1) to muconaldehyde (4) in a relatively mild, one-pot process has led us to examine whether the method can be expanded to other carboxylic acids. We report here our findings using benzoic acid as a representative substrate.

Evolution Of Microscopic Heterogeneity And Dynamics In Choline Chloride-Based Deep Eutectic Solvents, Stephanie Spittle, Derrick Poe, Brain Doherty, Charles Kolodziej, Luke Heroux, Md Ashraful Haque, Henry Squire, Tyler Cosby, Yong Zhang, Carla Fraenza, Sahana Bhattacharyya, Madhusudan Tyagi, Jing Peng, Ramez A. Elgammal, Thomas Zawodzinski, Mark Tuckerman, Steve Greenbaum, Burcu Gurkan, Clemens Burda, Mark Dadmun, Edward J. Maginn, Joshua Sangoro

Publications and Research

Deep eutectic solvents (DESs) are an emerging class of non-aqueous solvents that are potentially scalable, easy to prepare and functionalize for many applications ranging from biomass processing to energy storage technologies. Predictive understanding of the fundamental correlations between local structure and macroscopic properties is needed to exploit the large design space and tunability of DESs for specific applications. Here, we employ a range of computational and experimental techniques that span length-scales from molecular to macroscopic and timescales from picoseconds to seconds to study the evolution of structure and dynamics in model DESs, namely Glyceline and Ethaline, starting from the parent …

Wastewater-Based Estimation Of Substances Discharged At The Rest Areas Along The State Highways In Kentucky, Katherine E. Gray, Eugene Shin, Tyler Whitt, Andrew Windhorst, Houston Hampton, Chris Delcher, Bikram Subedi

Posters-at-the-Capitol

The availability of licit and illicit stimulants and its adverse consequences on public health has emerged as a major drug threat to communities in the United States. Despite several drug-involved traffic incidents along the interstate highways, this report represents the first comprehensive and quantitative report of drugs discharged at the rest areas along the interstate highways. In this National Institute of Justice-funded study, the amount of several discharged drugs focusing on stimulants but also including opioids and prescription antipsychotics are being measured in raw wastewater collected from five rest areas and a truck servicing facility using a state-of-the-art mass …

Iron Dysregulation In Covid-19 And Reciprocal Evolution Of Sars-Cov-2: Natura Nihil Frustra Facit, Yash Gupta, Dawid Maciorowski, Brian Medernach, Daniel P. Becker Ph.D., Ravi Durvasula, Claudia R. Libertin, Prakasha Kempaiah

Chemistry: Faculty Publications and Other Works

After more than a year of the COVID-19 pandemic, SARS-CoV-2 infection rates with newer variants continue to devastate much of the world. Global healthcare systems are overwhelmed with high positive patient numbers. Silent hypoxia accompanied by rapid deterioration and some cases with septic shock is responsible for COVID-19 mortality in many hospitalized patients. There is an urgent need to further understand the relationships and interplay with human host components during pathogenesis and immune evasion strategies. Currently, acquired immunity through vaccination or prior infection usually provides sufficient protection against the emerging variants of SARS-CoV-2 except Omicron variant requiring recent booster. New …

Radical-Initiated Brown Carbon Formation In Sunlit Carbonyl–Amine–Ammonium Sulfate Mixtures And Aqueous Aerosol Particles, Natalie G. Jimenez, Kyle D. Sharp, Tobin Gramyk, Duncan Z. Ugland, Matthew-Khoa Tran, Antonio Rojas, Michael A. Rafla, Devoun Stewart, Melissa M. Galloway, Peng Lin, Alexander Laskin, Mathieu Cazaunau, Edouard Pangui, Jean-François Doussin, David O. De Haan

Chemistry and Biochemistry: Faculty Scholarship

Brown carbon (BrC) formed from glyoxal+ammonium sulfate (AS) and methylglyoxal+AS reactions photobleaches quickly, leading to the assumption that BrC formed overnight by Maillard reactions will be rapidly destroyed at sunrise. Here, we tested this assumption by reacting glyoxal, methylglyoxal, glycolaldehyde, or hydroxyacetone in aqueous mixtures with reduced nitrogen species at pH 4–5 in the dark and in sunlight (>350 nm) for at least 10 h. The absorption of fresh carbonyl+AS mixtures decreased when exposed to sunlight, and no BrC formed, as expected from previous work. However, the addition of amines (either methylamine or glycine) allowed BrC to form in …

Synthesis Of Methanediol [Ch2(Oh)2]: The Simplest Geminal Diol, Cheng Zhu, N. Fabian Kleimeier, Andrew M. Turner, Santosh K. Singh, Ryan C. Fortenberry, Ralf I. Kaiser

Faculty and Student Publications

Geminal diols—organic molecules carrying two hydroxyl groups at the same carbon atom—have been recognized as key reactive intermediates by the physical (organic) chemistry and atmospheric science communities as fundamental transients in the aerosol cycle and in the atmospheric ozonolysis reaction sequence. Anticipating short lifetimes and their tendency to fragment to water plus the aldehyde or ketone, free geminal diols represent one of the most elusive classes of organic reactive intermediates. Here, we afford an exceptional glance into the preparation of the previously elusive methanediol [CH2(OH)2] transient—the simplest geminal diol—via energetic processing of low-temperature methanol–oxygen ices. Methanediol was identified in the …

Investigation Of Metastable Low Dimensional Halometallates, Navindra Keerthisinghe, Matthew S. Christian, Anna A. Berseneva, Gregory Morrison, Vladislav V. Klepov, Mark D. Smith, Hans Conrad Zur Loye

Faculty Publications

The solvothermal synthesis, structure determination and optical characterization of five new metastable halometallate compounds, [1,10-phenH][Pb_3.5I₈] (1), [1,10-phenH₂][Pb₅I₁₂]·(H₂O) (2), [1,10-phen][Pb₂I₄] (3), [1,10-phen]₂[Pb₅Br₁₀] (4) and [1,10-phenH][SbI₄]·(H₂O) (5), are reported. The materials exhibit rich structural diversity and exhibit structural dimensionalities that include 1D chains, 2D sheets and 3D frameworks. The optical spectra of these materials are consistent with bandgaps ranging from 2.70 to 3.44 eV. We show …

Ultrafast Dynamics Of Nitro−Nitrite Rearrangement And Dissociation In Nitromethane Cation, Mi'kayla D. Word, Hugo Andres Lopez Pena, Derrick Ampadu Boateng, Shane L. Mcpherson, Gennady L. Gutsev, Lavrenty Gutsev, Ka Un Lao, Katharine M. Tibbetts

Chemistry Publications

We report new insights into the ultrafast rearrange- ment and dissociation dynamics of nitromethane cation (NM+) using pump−probe measurements, electronic structure calculations, and ab initio molecular dynamics simulations. The “roaming” nitro−nitrite rearrangement (NNR) pathway involving large- amplitude atomic motion, which has been previously described for neutral nitromethane, is demonstrated for NM+. Excess energy resulting from initial population of the electronically excited D2 state of NM+ upon strong-field ionization provides the necessary energy to initiate NNR and subsequent dissociation into NO+. Both pump−probe measurements and molecular dynamics simulations are consistent with the completion of NNR within 500 fs of ionization with …

Harmful Algal Blooms In Caesar Creek Lake And Their Relationship To Riparian Cover, Morgan C. Grunden

Browse all Theses and Dissertations

Caesar Creek Lake (CCL) in Warren County, OH has recently been experiencing harmful algal blooms (HABs) which are most likely attributed to an excess of phosphorus (P) from fertilizers and manures applied to surrounding fields. Sediments act as a sink for P later supplying a source of P in lakes for HABs when waters become thermally stratified and anoxic. This study seeks to determine the relationship between HABs in CCL and riparian cover at the main tributaries, Anderson Fork and Caesar Creek. In order to do this, sediment samples were collected from four sample sites along Anderson Fork and three …

The Chemical Characterization Of Microplastic Polymer Composition From Various Littoral Environments On Cape Cod, Massachusetts, Leah Kosovsky

Chemistry Honors Papers

The increasing abundance of microplastic pollution in marine environments is a rising concern, and it has the potential to negatively affect the health and sustainability of marine organisms and ecosystems. Microplastics can harm organisms through a variety of chemical, biological, and physical mechanisms. The extent to which they are harmful varies greatly and is significantly dependent on the chemical and physical makeup of the plastic polymer. Due to this variability, it is important to characterize microplastic samples in various environments to better understand the risks associated with the debris in certain areas. Through field research, a spatial analysis of the …

Shapes Of Molecular Aggregates Associated With A Critical Point Of Solution, James Baird

Summer Community of Scholars (RCEU and HCR) Project Proposals

No abstract provided.

Chapter 3.2: Why Batteries Deliver A Fairly Constant Voltage Until They Suddenly Die: An Application Of Nernst Topo Surfaces, Garon C. Smith, Md Mainul Hossain, Patrick Maccarthy

Water Topos: A 3-D Trend Surface Approach to Viewing and Teaching Aqueous Equilibrium Chemistry

Two characteristics of batteries, their delivery of nearly constant voltage and their rapid failure, are explained through a visual examination of the Nernst equation. Two Galvanic cells are described in detail: (1) a wet cell involving iron and copper salts and (2) a mercury oxide dry cell. A complete description of the wet cell requires a three-dimensional Nernst surface because the potential is a function of two variables: the activities of both the oxidized and reduced forms in each redox couple. Dry cell potentials, which utilize solid or pure liquid species, are functions of only one variable and can be …

Covalent Attachment Of Tadf Chromophores To Thermally Stable Poly(Arylene Ether)S, Samuel Farrar

Browse all Theses and Dissertations

The covalent attachment of a blue emitting, benzothiazole based TADF chromophore into poly(arylene ether) backbone polymers was explored. A benzothiazole derivative, 2-(2,4-difluorophenyl)-benzothiazole (2,4-diF-BTZ), was synthesized to form the electrophilic component of the host polymer. Two polymers were synthesized to have chromophore incorporated, using 2,4-diFBTZ and 4,4-dihydroxydiphenyl ether (DPE) or 4,4’-biphenol (BP). The chromophore was covalently incorporated at a 10% molar ratio into the polymer backbone by copolymerization with 2,4-diF-BTZ and BP, utilizing nucleophilic aromatic substitution (NAS). Structural characterization was provided via NMR spectroscopy and GC/MS analysis. The polymer syntheses provided high molecular weight materials that were able to be cast …

From Balancing Redox Reactions To Determining Change Of Oxidation Numbers, Pong Kau Yuen, Cheng Man Diana Lau

Faculty Publications

Redox reaction is a core concept in teaching and learning chemistry. This article explores a new method for balancing organic redox reactions that requires the balancing of both atoms and charges. The H+, O, H2O, and e– are used as balanced vehicles in two half reactions. A non-oxidation number approach can be applied to both molecular and ionic equations. The article also provides standard operating procedures and examples. The number of transferred electrons is first determined by balancing a half redox reaction; consequently; the change of oxidation numbers can be calculated. The mathematical equation of Te– = n Te– = …

Heterogenous Reduction Of Co2 Over Boron-Rich Alb2, Jose C. Berger

Honors Undergraduate Theses

Evidence suggests that the recent drastic changes in the global climate have been caused by greenhouse gases, especially CO­₂. As a result, scientists are aiming to develop processes that either minimize the production of these gases or convert them into products of higher value. To that end, the catalytic properties of a two-dimensional boron-rich material were investigated. Herein is reported that such a material can reduce CO₂ into benzene, C₃ species, and C₄ species at relatively low temperatures (225-450 ℃) and pressures (0.38 MPa). Current data suggest that a low-temperature induction period (e.g., 225 ℃) …

A Core–Shell Au@Tio2 And Multi-Walled Carbon Nanotube-Based Sensor For The Electroanalytical Determination Of H2o2 In Human Blood Serum And Saliva, Ayman Ali Saeed, Mohammed Nooredeen Abbas, Waheed Fathi El-Hawary, Yousry Moustafa Issa, Baljit Singh

Articles

A hydrogen peroxide (H2O2) sensor was developed based on core–shell gold@ titanium dioxide nanoparticles and multi-walled carbon nanotubes modified glassy carbon electrode (Au@TiO2/MWCNTs/GCE). Core–shell Au@TiO2 material was prepared and characterized using a scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDX), transmission electron microscopy (TEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD) and Zeta-potential analyzer. The proposed sensor (Au@TiO2/MWCNTs/GCE) was investigated electrochemically using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The analytical performance of the sensor was evaluated towards H2O2 using differential pulse voltammetry (DPV). The proposed sensor exhibited excellent stability and sensitivity with a linear concentration …

Inhibitors Of Alpha-Synuclein Aggregation, Jemil Ahmed

Electronic Theses and Dissertations

Alpha-Synuclein (αS) – a neuronal, disordered, presynaptic protein – aggregates into amyloid fibrils and accumulates in the substantia nigra pars compacta of Parkinson's Disease (PD) patients. The aggregation and accumulation of αS amyloid fibrils leads to death of dopaminergic neurons; a hallmark of PD. Although it’s not clear why αS aggregates, prior studies have found that intrastriatal injection of fibril alone is sufficient to cause PD pathology in mouse and non-human primates models. These observations implicate αS as a therapeutic target against PD.

Unfortunately, there are three caveats when attempting to target αS. First, αS is a neuronal protein expressed …

Characterization Of Cyclopropyl Synthases Involved In The Maturation Of Ribosomally Synthesized And Posttranslationally Modified Peptides, Yi Lien

Electronic Theses and Dissertations

Ribosomally synthesized and post-translationally modified peptides (RiPPs) are a large class of natural products with significant human health implications. RiPPs are synthesized from a genetically encoded precursor peptide that undergoes significant modifications by maturing enzymes, or maturases. Recently, radical-S-adenosylmethionine (rSAM) enzymes have emerged as an important family of RiPP maturases. rSAM enzymes have been shown to install ether, thioether, and carbon-carbon bonds on the precursor peptide. These modifications usually define the backbone structure of the mature RiPP. This thesis describes the characterization of a novel RiPP modification catalyzed by the radical S-adenosylmethionine enzyme TigE. TigE belongs to the TIG biosynthetic …