Chemistry Commons^™

Additive-Free Palladium-Catalyzed Decarboxylative Cross-Coupling Of Aryl Chlorides, Ryan A. Daley, En Chih Liu, Joseph J. Topczewski

Chemistry Faculty Research & Creative Works

The cross-coupling of sodium (hetero)aryl carboxylates with (hetero)aryl chlorides proceed with 1 mol % palladium catalyst and does not require inorganic base, silver salts, or copper salts. This coupling uses two low energy partners, and the only stoichiometric byproducts are carbon dioxide and sodium chloride. The substrate scope includes less activated aryl chlorides and carboxylates (>25 examples). The palladium loading could be reduced to 0.1 mol %, and Buchwald-style precatalysts could be used.

Kinetic Resolution Of Cyclic Secondary Azides, Using An Enantioselective Copper-Catalyzed Azide-Alkyne Cycloaddition, Juliana R. Alexander, Amy A. Ott, En Chih Liu, Joseph J. Topczewski

Chemistry Faculty Research & Creative Works

An enantioselective copper-catalyzed azide-alkyne cycloaddition (E-CuAAC) is reported by kinetic resolution. Chiral triazoles were isolated in high yield with limiting alkyne (up to 97:3 enantiomeric ratio (er)). A range of substrates were tolerated (>30 examples), and the reaction was scaled to >1 g. The er of a triazole product could be enhanced by recrystallization and the recovered scalemic azide could be racemized and recycled. Recycling the azide allows efficient use of the undesired azide enantiomer.

The Transformative Possibilities Of The Microbiota And Mycobiota For Health, Disease, Aging, And Technological Innovation, Lucas Jones, Jessica Kumar, Adil Mistry, Thriveen Sankar Chittoor Mana, George Perry, Prakash Reddy, Mark Obrenovich

Chemistry Faculty Research & Creative Works

The gut microbiota is extremely important for the health of the host across its lifespan. Recent studies have elucidated connections between the gut microbiota and neurological disease and disorders such as depression, anxiety, Alzheimer's disease (AD), autism, and a host of other brain illnesses. Dysbiosis of the normal gut flora can have negative consequences for humans, especially throughout key periods during our lifespan as the gut microbes change with age in both phenotype and number of bacterial species. Neurologic diseases, mental disorders, and euthymic states are influenced by alterations in the metabolites produced by gut microbial milieu. We introduce a …

Facile And Label-Free Electrochemical Biosensors For Microrna Detection Based On Dna Origami Nanostructures, Shuo Han, Wenyan Liu, Shuo Yang, Risheng Wang

Chemistry Faculty Research & Creative Works

MicroRNAs (miRNAs) have emerged as the promising molecular biomarkers for early diagnosis and enhanced understanding of the molecular pathogenesis of cancers as well as certain diseases. Here, a facile, label-free, and amplification-free electrochemical biosensor was developed to detect miRNA by using DNA origami nanostructure-supported DNA probes, with methylene blue (MB) serving as the hybridization redox indicator, for the first time. Specifically, the use of cross-shaped DNA origami nanostructures containing multiple single-stranded DNA probes at preselected locations on each DNA nanostructure could increase the accessibility and the recognition efficiency of the probes (due to the rational controlled density of DNA probes). …

Iron Detection And Remediation With A Functionalized Porous Polymer Applied To Environmental Water Samples, Sumin Lee, Adam Uliana, Mercedes K. Taylor, Gary J. Long, Fernande Grandjean, For Full List Of Authors, See Publisher's Website.

Chemistry Faculty Research & Creative Works

Iron is one of the most abundant elements in the environment and in the human body. As an essential nutrient, iron homeostasis is tightly regulated, and iron dysregulation is implicated in numerous pathologies, including neuro-degenerative diseases, atherosclerosis, and diabetes. Endogenous iron pool concentrations are directly linked to iron ion uptake from environmental sources such as drinking water, providing motivation for developing new technologies for assessing iron(ii) and iron(iii) levels in water. However, conventional methods for measuring aqueous iron pools remain laborious and costly and often require sophisticated equipment and/or additional processing steps to remove the iron ions from the original …

Ultrasensitive And Highly Selective Ni₃Te₂ As A Nonenzymatic Glucose Sensor At Extremely Low Working Potential, Bahareh Golrokh Amin, Umanga De Silva, Jahangir Masud, Manashi Nath

Chemistry Faculty Research & Creative Works

Developing Nonenzymatic glucose biosensors has recently been at the center of attention owing to their potential application in implantable and continuous glucose monitoring systems. In this article, nickel telluride nanostructure with the generic formula of Ni₃Te₂ has been reported as a highly efficient electrocatalyst for glucose oxidation, functional at a low operating potential. Ni₃Te₂ nanostructures were prepared by two synthesis methods, direct electrodeposition on the electrode and hydrothermal method. The electrodeposited Ni₃Te₂ exhibited a wide linear range of response corresponding to glucose oxidation exhibiting a high sensitivity of 41.615 mA cm …

In Situ Nmr Parameter Monitoring Systems And Methods For Measuring Ph And Temperature, Ming Huang, Lingyu Chi, Rex E. Gerald Ii, Jie Huang, Annalise R. Pfaff, Klaus Woelk

Electrical and Computer Engineering Faculty Research & Creative Works

Devices and methods are provided for measuring temperatures and pHs of a sample in situ using NMR spectroscopy, and for sealing one or more ends of a capillary tube after a reference material has been added to the capillary tube, which is used in an in situ NMR temperature measurement device. A method for measuring a pH of a sample in situ using NMR spectroscopy includes providing an in situ NMR pH measurement device. This device includes a sample housing member configured to house a target sample, at least one pH sensor configured to exhibit an NMR spectral change due …

The Protective Effect Of N-Acetylcysteine Amide Against Paraquat-Induced Neurotoxicity, Burhan Ates, Nigar Vardi, Hakan Parlakpinar, Merve Goksin Karaaslan, Ismet Yilmaz, Nuran Ercal

Chemistry Faculty Research & Creative Works

N-acetylcysteine amide (NACA) is a new antioxidant molecule with powerful radical scavenging properties. The aim of this study was to investigate neuroprotective effects of NACA against paraquat (PQ) toxicity in the midbrains of rats by using motor coordination tests and biochemical and histological analysis. Thirty adult Wistar albino rats were divided into three groups: Group 1: control (n = 10), Group 2: PQ (10 mg/kg) (n = 10), and Group 3: PQ (10 mg/kg) + NACA (100 mg/kg) (n = 10). NACA was administrated intraperitoneally 30 min before PQ injection. Performance was measured for a period of 28 days. The …

Computational Investigation On Electronic Structures And Properties Of 4,6-Bis(Nitroimino)-1,3,5-Triazinan-2-One: An Insensitive Munition Compound, Katarina M. Pittman, Harley R. Mcalexander, Gregory S. Tschumper, Manoj K. Shukla

Chemistry Faculty Research & Creative Works

In order to minimize unintentional detonation, munitions researchers have focused on the development of chemical compounds that are insensitive to external stimuli while maintaining their effectiveness. Although these compounds, known as high-performance insensitive munition compounds, are promising in terms of potency and stability, their environmental impacts have either not been fully understood or are yet to be investigated. In the present research, we have performed a quantum chemical investigation on electronic structures and properties of an insensitive munition compound 4,6-bis(nitroimino)-1,3,5-triazinan-2-one (DNAM). The density functional theory using the B3LYP and M06-2X functionals and MP2 methodology were used for geometry optimization of …

Enantioselective Copper Catalyzed Alkyne-Azide Cycloaddition By Dynamic Kinetic Resolution, En Chih Liu, Joseph J. Topczewski

Chemistry Faculty Research & Creative Works

The copper(I) catalyzed alkyne-azide cycloaddition (CuAAC), a click reaction, is one of the most powerful catalytic reactions developed during the last two decades. Conducting CuAAC enantioselectively would add a third dimension to this reaction and would enable the direct synthesis of α-chiral triazoles. Doing so is demanding because the two precursors have linear geometries, and the triazole product is a flat heterocycle. Designing a chiral catalyst is further complicated by the complex mechanism of CuAAC. We report an enantioselective CuAAC (E-CuAAC), enabled by dynamic kinetic resolution (DKR). The E-CuAAC is high yielding and affords up to 99:1 er. The E-CuAAC …

Molecular Dynamics Simulations Of Substrate Release From Trypanosoma Cruzi Udp-Galactopyranose Mutase, Rodrigo Cossio-Pérez, Gustavo Pierdominici-Sottile, Pablo Sobrado, Juliana Palma

Chemistry Faculty Research & Creative Works

The enzyme UDP-galactopyranose mutase (UGM) represents a promising drug target for the treatment of infections with Trypanosoma cruzi. We have computed the Potential of Mean Force for the release of UDP-galactopyranose from UGM, using Umbrella Sampling simulations. The simulations revealed the conformational changes that both substrate and enzyme undergo during the process. It was determined that the galactopyranose portion of the substrate is highly mobile and that the opening/closing of the active site occurs in stages. Previously uncharacterized interactions with highly conserved residues were also identified. These findings provide new pieces of information that contribute to the rational design of …

Radical Scavenging Of Poly(Methyl Methacrylate) Bone Cement By Rifampin And Clinically Relevant Properties Of The Rifampin-Loaded Cement, G. A. Funk, E. M. Menuey, K. A. Cole, Thomas P. Schuman, K. V. Kilway, T. E. Mciff

Chemistry Faculty Research & Creative Works

Objectives: The objective of this study was to characterize the effect of rifampin incorporation into poly(methyl methacrylate) (pMMA) bone cement. While incompatibilities between the two materials have been previously noted, we sought to identify and quantify the cause of rifampin's effects, including alterations in curing properties, mechanical strength, and residual monomer content.

Methods: Four cement groups were prepared using commercial pMMA bone cement: a control; one with 1 g of rifampin; and one each with equimolar amounts of ascorbic acid or hydroquinone relative to the amount of rifampin added. The handling properties, setting time, exothermic output, and monomer loss were …

Examination Of The Structures, Energetics, And Vibrational Frequencies Of Small Sulfur-Containing Prototypical Dimers, (H2s)2 And H2o/H2s, Katelyn M. Dreux, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

The optimized geometries, vibrational frequencies, and dissociation energies from MP2 and CCSD(T) computations with large correlation consistent basis sets are reported for (H₂S)₂ and H₂O/H₂S. Anharmonic vibrational frequencies have also been computed with second-order vibrational perturbation theory (VPT2). As such, the fundamental frequencies, overtones, and combination bands reported in this study should also provide a useful road map for future spectroscopic studies of the simple but important heterogeneous H₂O/H₂S dimer in which the hydrogen bond donor and acceptor can interchange, leading to two unique minima with very similar energies. …

Development And Demonstration Of Sampling Techniques For A Chirped Pulse Fourier Transform Microwave Spectrometer, Frank Edward Marshall

Doctoral Dissertations

"With the introduction of the Chirped Pulse-Fourier Transform Microwave Spectrometer in the past decade, it has become possible to rapidly study the rotational spectra of molecules in the gas phase. It is possible to study molecules that are not normally in the gas phase through the use of various sourcing techniques. The development of both the heated nozzle and the laser ablation sourcing techniques allow for the study of liquids and solids, respectively. The design and performance of these sources will be presented in detail and discussed. Additionally, the development of a Multi-Antennae detection scheme, useful in improving overall sensitivity …

Mass Spectrometry Analysis Of Contaminants Of Emerging Concern: Nanoparticles, Algal Toxins, And Cyanotoxins In Natural Waters And Their Potential Health Impacts, Ariel R. Donovan

Doctoral Dissertations

“The analysis of contaminants of emerging concern is critical to protecting environmental health. In the presented dissertation, two groups of contaminants of emerging concern were assessed using mass spectrometry methods: nanoparticles and algal and cyanotoxins.

Analysis of metal oxide nanoparticles in environmental matrices has been a challenging issue, as most traditional methods require complicated sample preparation methods or that can alter or destroy the nanoparticles in the system. Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) methods were used to detect metal oxide nanoparticles in surface waters and their removal through drinking water treatment simulations while retaining all information regarding …

Development Of Functional Ionic Liquids For Separation And Recovery Of Rare Earth Elements, Mostafa Khodakarami

Doctoral Dissertations

“This research focused on the design and synthesis of task-specific ionic liquids for enhanced extraction and separation of rare earth elements (REEs). Two novel ammonium-based functional ionic liquids (FILs) with oxygen donating groups: trioctyl(2-ethoxy-2-oxoethyl)ammonium dihexyl diglycolamate, [OcGBOEt][DHDGA], and tricaprylmethylammonium dihexyl diglycolamate, [A336][DHDGA] were synthesized and tested for the recovery and separation of selected REEs from aqueous solutions. Functionalities with different denticities were incorporated into both anionic and cationic parts of ionic liquids, which are solely composed of incinerable atoms including C, H, O, and N. The structural, physical, and chemical properties of the synthesized FILs were studied using nuclear magnetic …

Cis/Trans Energetics In Epoxide, Thiirane, Aziridine And Phosphirane Containing Cyclopentanols: Effects Of Intramolecular Oh···O,S,N And P Contacts, Ben E. Smith, Jeremy M. Carr, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

A recent computational analysis of the stabilizing intramolecular OH···O contact in 1,2-dialkyl-2,3-epoxycyclopentanol diastereomers has been extended to thiiriane, aziridine and phosphirane analogues. Density functional theory (DFT), second-order Møller-Plesset perturbation theory (MP2) and CCSD(T) coupled-cluster computations with simple methyl and ethyl substituents indicate that electronic energies of the cis isomers are lowered by roughly 3 to 4 kcal mol⁻¹ when the OH group of these cyclopentanol systems forms an intramolecular contact with the O, S, N or P atom on the adjacent carbon. The results also suggest that S and P can participate in these stabilizing intramolecular interactions as effectively …

Bending Wave Based Characterization Of Viscoelastic Materials, Max Miller, Sadeq Malakooti, Tahereh Taghvaee, Ning Xiang, Hongbing Lu, Nicholas Leventis

Chemistry Faculty Research & Creative Works

Obtaining broadband dynamic mechanical properties of viscoelastic materials is challenging. Commercially available characterization equipment is typically limited to about 500 Hz. Ultrasonic testing is a common strategy but requires time-temperature superposition extrapolation to audible frequencies. These techniques are indirect and sensitive to inhomogeneities. Modal methods do not yield broadband data and can fail for materials with high loss factors. A new relatively simple characterization method, relying on bending wave excitation and laser Doppler vibrometer measurement, is proposed. Complex elastic moduli and phase speeds are now attainable over the entire range of building acoustics frequencies. The materials under test are an …

Removal Of Antimony And Bismuth From Copper Electrorefining Electrolyte By Two Proprietary Solvent Extraction Extractants, Andrew Artzer

Masters Theses

"Antimony and bismuth are two of the most problematic impurities in copper electrorefining (ER). Because of this, much research has been done investigating the ways to remove them. Processes that are currently being used industrially include anode additions, liberators, ion exchange (IX), and solvent extraction (SX). Of these, liberators and anode additions are the most common while SX is the least, mostly being used for arsenic removal. There are other methods that have been evaluated, but are not in commercial use. These include the use of various electrolyte additives, and adsorbents such as bentonite clay and heavy metal sulfates.

Two …

Flavin Oxidation In Flavin-Dependent N-Monooxygenases, Reeder M. Robinson, Catherine A. Klancher, Pedro J. Rodriguez, Pablo Sobrado

Chemistry Faculty Research & Creative Works

Siderophore A (SidA) from Aspergillus fumigatus is a flavin-containing monooxygenase that hydroxylates ornithine (Orn) at the amino group of the side chain. Lysine (Lys) also binds to the active site of SidA; however, hydroxylation is not efficient and H₂O₂ is the main product. The effect of pH on steady-state kinetic parameters was measured and the results were consistent with Orn binding with the side chain amino group in the neutral form. From the pH dependence on flavin oxidation in the absence of Orn, a pKa value >9 was determined and assigned to the FAD-N5 atom. In the …

Dynamical Interference In The Vibronic Bond Breaking Reaction Of Hco, Shanyu Han, Xianfeng Zheng, Steve A. Ndengue, Yu Song, Richard Dawes, For Full List Of Authors, See Publisher's Website.

Chemistry Faculty Research & Creative Works

First-principles treatments of quantum molecular reaction dynamics have reached the level of quantitative accuracy even in cases with strong non-Born-Oppenheimer effects. This achievement permits the interpretation of puzzling experimental phenomena related to dynamics governed by multiple coupled potential energy surfaces. We present a combined experimental and theoretical study of the photodissociation of formyl radical (HCO). Oscillations observed in the distribution of product states are found to arise from the interference of matter waves-a manifestation analogous to Young's double-slit experiment.

Electrodeposition Of Epitaxial Metal Thin Films On Silicon For Energy Conversion And Flexible Electronics, Qingzhi Chen

Doctoral Dissertations

"This research focuses on epitaxial electrodeposition of two coinage metals: Au and Ag thin films on the silicon surface and their applications in flexible electronics and energy conversion and storage. The first paper: Photoelectrochemistry of ultrathin, semi-transparent, and catalytic gold films electrodeposited epitaxially onto n-silicon (111) describes the epitaxial electrodeposition of Au thin films on n-type Si using a simple HAuCl4 bath and the photoelectrochemical properties of the Au-Si junction barrier. The effect of the Au layer on the interfacial energetics as well as the stability of the photoelectrode as a function of the Au coverage/thickness is determined in a …

Nanomorphology Dependent Optical And Mechanical Properties Of Aerogels, Chandana Mandal

Doctoral Dissertations

"Aerogels are very low density, light weight open pore materials. A hypothesis that is under intense current investigation by the scientific community states that the mechanical properties of nanostructured polymers depend on their nanomorphology. Aerogels are nanostructured ultra-lightweight nanoporous materials with skeletal frameworks that can display a wide range of nanomorphologies. Thereby aerogels comprise a suitable platform for testing not only that hypothesis but also a wide range of other properties such as light scattering for applications, for example, in thermally insulating windows.

To study the mechanical properties of nanostructured matter as a function of nanomorphology, various shape-memory polyurethane aerogels …

Synthesis And Applications Of Ceramic (Silicon Carbide And Silicon Nitride), Metallic (Cobalt(0)) And Polymeric (Polyurethane) Aerogels, Parwani M. Rewatkar

Doctoral Dissertations

"A new method has been demonstrated for the synthesis of monolithic ceramic and purely metallic aerogels from xerogel powder compacts, and the use of polyurethane aerogels based on cyclodextrins as efficient desiccants.

I. Highly porous ( > 80%) monolithic SiC and Si₃N₄, aerogels were prepared from compressed compacts of polyurea-crosslinked silica xerogel powders. The process is time efficient as solvent-exchange through powders is fast, and energy efficient as it bypasses drying with supercritical fluids. The final ceramic objects were chemically pure, sturdy, with compressive moduli at 37 ±7 MPa and 59 ± 7 MPa, and thermal conductivities …

High Level Thermochemical And Spectroscopic Computations For Molecules Relevant To Combustion And The Atmosphere, Bradley K. Welch

Doctoral Dissertations

"Computational thermochemistry can be a complicated multistep process, but in recent years has become an equal partner with experiment. Many important molecules in combustion systems or in the atmosphere (such as short-lived radicals) are difficult to study experimentally. Predicting highly accurate thermochemistry is a key aspect in understanding these species. In this project, computational thermochemistry was developed into an automated streamlined procedure and then used to understand the methyl and ethyl peroxy families of radicals. This effort involved optimizing a standard workflow for computational thermochemistry. Computational thermochemistry generally requires numerous individual calculations whose cost and scalings vary widely. Conducting such …

Polyurea Aerogels: From Nanoscopic To Macroscopic Properties, Tahereh Taghvaee

Doctoral Dissertations

"The morphology of a material is intrinsically a qualitative property and in order to relate nanomorphology to synthetic conditions, it is necessary to express nano/micro-structure quantitatively. In this context, polyurea aerogels were chosen as a model system with demonstrated potential for rich nanomorphology and being guided by a statistical Design-of-Experiments model, a large array of materials (208) with identical chemical composition, but quite different nanostructures were prepared. By reflecting upon the SEM images, it was realized that our first pre-verbal impression about a nanostructure is related to its openness and texture; the former is quantified by porosity (Π), and the …

Design, Synthesis, Characterization And Anti-Cancer Effects Evaluation Of Interchain Cysteine Linked Antibody Drug Conjugates, Ke Li

Doctoral Dissertations

"Antibody drug conjugates (ADCs) are emerging therapeutic products specially designed for the treatment of cancers. Potent cytotoxic agents are linked to antibodies via linkers. Antibody drug conjugates, which take advantage of both antibodies and cytotoxic agents, showed high selectivity towards cancer cells. Cytotoxic agents are delivered to the cancer cells selectively and kill them from inside while leaving low or non-toxicity towards normal cells. Antibody drug conjugates are actually heterogeneous mixtures. The major heterogeneities mainly lie in the drug to antibody ratio (DAR) and drug linking positions, both of which potentially affect the therapeutic index of ADCs. In this research, …

Designing Novel Multinary Transition Metal Selenides As High-Efficiency Oxygen Evolution Reaction Electrocatalysts And Investigating Surface Properties, Xi Cao

Doctoral Dissertations

”Water splitting has been widely considered to be an efficient way to generate sustainable and renewable energy resources in fuel cells, metal-air batteries and other energy conversion devices. Exploring efficient electrocatalysts to expedite the anodic oxygen evolution reaction (OER) is a crucial task that needs to be addressed to boost the practical application of water splitting. This research focuses on the identification of OER electrocatalysts by systematically designing non-stochiometric mixed transition metal-based selenide OER electrocatalysts through combinatorial electrodeposition and investigation of selenide-based naturally occurring minerals as effective OER electrocatalyst. Paper I describes the study of Ni-Fe-Co selenides as OER catalysts …

Exploring Transition Metal Chalcogenides For Bio Sensing And Environmental Remediation, Bahareh Golrokh Amin

Doctoral Dissertations

“Electrocatalysts play an inevitable role in many applications including energy storage, energy conversion, and biosensing. The state-of-the-art noble metal-based electrocatalysts have long been used in full water splitting, non-enzymatic glucose sensing, and supercapacitors. However, scarcity and high cost of noble metals restrict utilization of such electrocatalysts in large-scale implementations. Transition metal-based electrodes have been considered as a potential solution to address these drawbacks as well as to enhance the electrocatalytic performance. In this work, applicability of non-oxidic transition metal based electrocatalysts is evaluated. Transition metal chalcogenides are expected to have high catalytic performance owing to their facilitated electron cloud delocalization …

Three-Dimensional Nanotube Arrays For Solar Energy Harvesting And Production Of Solar Fuels, Wipula P. R. Liyanage

Doctoral Dissertations

"Over the past decade extensive research has been carried out on photovoltaic semiconductors to provide a solution towards a renewable energy future. Fabricating high-efficiency photovoltaic devices largely rely on nanostructuring the photoabsorber layers due to the ability of improving photoabsorption, photocurrent generation and transport in nanometer scale. Vertically aligned, highly uniform nanorods and nanowire arrays for solar energy conversion have been explored as potential candidates for solar energy conversion and solar-fuel generation owing to their enhanced photoconversion efficiencies.

However, controlled fabrication of nanorod and especially nanotube arrays with uniform size and shape and a pre-determined distribution density is still a …