Chemistry Commons^™

Stereochemical Control In Suzuki Cross Coupling Reactions Of Acyclic (Z)-Beta-Haloacroleins, William Carrick

Honors Theses

Beta-chloroenals are readily accessible substances and are efficient precursors for a variety of heterocyclic compounds. Suzuki type cross-coupling reactions of such compounds with arylboronic acids yield ��,��-diarylacroleins with control of stereochemistry. The oxidation of these enals to the corresponding acids and subsequent oxidative lactonization leads to formation of the respective coumarins. The chemistry involved in these transformations with special attention to stereochemistry of the Suzuki coupling reaction will be discussed. A full NMR analysis involving 1H, 13C, COSY, NOESY, HSQC, and HMBC was performed to unambiguously confirm the structure and show that the reaction proceeds with retention of stereochemistry.

Chemical Shift Assignments Of The N-Terminal Domain Of Psd95 (Psd95-Nt), Yonghong Zhang, Johannes W. Hell, James B. Ames

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

Postsynaptic density protein-95 (PSD95) contributes to the postsynaptic architecture of neuronal synapses and plays an important role in controlling synaptic plasticity. The N-terminal domain of PSD95 (residues 1–71, called PSD95-NT) interacts with target proteins (calmodulin, α-actinin-1 and CDKL5), which regulate the Ca2+-dependent degradation of glutamate receptors. We report complete backbone NMR chemical shift assignments of PSD95-NT (BMRB No. 50752).

Synthesis And Conductivity Analysis Of A Methyl (Polyethylene Glycol) Comb Polymer, Olivia Fox

Honors Theses

The overall goal of work in this field is to improve materials for use in a variety of applications in fuel cell and battery production. This thesis specifically investigates the synthesis of two variations of a methyl (polyethylene glycol) comb polymer electrolyte (MePEG_nwhere n=7) to understand how the molecular structure of an ion-conducting polymer affects its electrochemical properties. The MePEG used in this synthesis contains seven ethylene glycol groups and was added to a poly (methylhydrosiloxane) comb polymer backbone. In the first sample, the polymer contained only the MePEG sidechain, and in the second sample, the polymer contained …

Biomedical Applications And Syntheses Of Selected Anthraquinone Dyes, Richard Sirard

Senior Honors Theses

Anthraquinones are aromatic organic compounds that have multiple applications in the biomedical field. Some anthraquinone-based compounds are used as fluorophores to contrast cell nuclei while others act as chemotherapeutic agents. However, there are not many fluorescent anthraquinone cell stains currently available. In this study, commercially available anthraquinone dyes, in addition to other dye families and compounds, were reviewed for their unique properties, advantages, and drawbacks. The development and characterization of three novel anthraquinone fluorophores revealed promising photophysical characteristics, like large Stokes shifts. One of the compounds, RBS3, was chosen for fixed and live cell staining and exhibited desirable biomedical properties. …

Modeling The Problem Of Integral Geometry On A Family Of Hyperbolic And Spherical Curves, Azamat Pirimbetov, N. Uteuliev, G. Djaykov

Karakalpak Scientific Journal

The problems of integral geometry in a strip on a family of curves of hyperbolic and spherical type are considered which have numerous applications in problems of geophysics, thermoacoustic and photoacoustic tomography. Explicit formulas are obtained for the Fourier image of the solution of integral geometry problems in the class of smooth compactly supported functions. Further, the obtained formulas are investigated for stability using numerical methods. To solve the problems, algorithms are constructed. Numerical and graphical results of applying these algorithms to solving the problems are presented.

Water Splitting By Mixed Chalcogenide Catalysts, Isabella Feltenstein

Undergraduate Research Conference at Missouri S&T

The depleting supply of fossil fuels has led to deeper investigation of water-splitting as a sustainable energy source. Specifically, using transition metal chalcogenides to catalyze the water-splitting reaction through oxygen and hydrogen evolution reactions. While the decreasing electronegativity of the chalcogenide group increases their activity, it also decreases their stability, leading to the investigation of mixed anion chalcogenides in order to keep both the stability and activity high. This research will further the understanding and efficiency of water-splitting for energy storage and inspire more research in the future. In these experiments, cobalt telluroselenide (Cox-Tey-Sez) and nickel telluroselenide (Nix-Tey-Sez) catalysts were …

Thermal, Mechanical, And Rehealing Properties Of Cross-Linked Ionene Networks, Katelyn Lindenmeyer

Honors College Theses

Polymers which contain ionic liquid groups have numerous applications in a wide variety of fields. Past research from our group has shown that IL-containing polymers which exist in covalently crosslinked networks can exhibit good ionic conductivities despite the hindrance in polymer chain mobility and relaxation. In part one of this thesis, efforts to create ionic networks which have the capability of being rehealed after exposure to an external stimulus are discussed. Thermoreversible maleimide-furan chemistry was incorporated into an imidazolium-containing ionene network. Maleimide-terminated, imidazolium-containing monomers were coupled with furan-functionalized monomers, prepared from commercially available multifunctional acrylates. Thermal, mechanical and rheological characterization …

Effect Of Precise Control Of Crosslink Density On The Thermal, Mechanical, And Conductive Properties Of Covalently Crosslinked Ionene Networks, Alexander Thome

Honors College Theses

Ionic liquids (ILs), besides being well known as environmentally friendly solvents, have attracted attention for a wide variety of other applications, including gas separation, 3D-printing and electrochemical actuators. However, for many such applications, incorporation of the IL moiety into a polymeric material eliminates the use of mechanically unstable free ILs while maintaining many of their electrochemical benefits. Such polymers can take two basic forms: poly(ionic liquid)s are ion-containing polymers in which the IL group is attached pendant to the polymeric backbone, while ionenes are ion-containing polymers in which the IL group is anchored directly into the backbone of the repeating …

Electrochemiluminescence Imaging Hydrogen Evolution Reaction On Single Platinum Nanoparticles Using A Bipolar Nanoelectrode Array, Xiang Qin, Zhong-Qiu Li, Jian-Bin Pan, Jian Li, Kang Wang, Xing-Hua Xia

Journal of Electrochemistry

A high-density (5.7 × 10⁸ cm^-2) nanoelectrode array with the electrode diameter of 200 nm and the interelectrode distance of 450 nm were fabricated. The nanoelectrode array consisted of gold nanowires embedded in a porous anodic aluminum oxide (AAO) matrix, having regular nanoelectrode distribution and highly uniform nanoelectrode size. The gold nanoelectrode array was used as a closed bipolar nanoelectrode array combined with electrochemiluminescence (ECL) method to map the electrocatalytic activity of platinum nanoparticles toward hydrogen evolution reaction (HER) by modifying the catalysts on single nanoelectrodes. Results show that HER on single bipolar nanoelectrodes could be imaged …

Preparation And Characterization Of "Water-In-Salt" Polymer Electrolyte For Lithium-Ion Batteries, Xu Hou, Xin He, Jie Li

Journal of Electrochemistry

Since the development of wearable and flexible electronic products, the demand of flexible energy storage devices such as batteries and super capacitors is in urgent. To enhance the safety and cycling stability for flexible lithium-ion batteries, “water-in-salt” polymer electrolyte was prepared by introducing 21 mol·kg^-1 LiTFSI electrolyte into cross-linked polyacrylamide (PAM) after freeze-drying. A great amount of holes with the size range of 10 ~ 20 μm can be found on the surface and in the bulk of polyacrylamide, which is benefited from the freeze-drying process and acts as a great support for the electrolyte uptake. The “water-in-salt” polymer …

Theoretical Studies Of Metal-N-C For Oxygen Reduction And Hydrogen Evolution Reactions In Acid And Alkaline Solutions, Xue-Ping Qin, Shang-Qian Zhu, Lu-Lu Zhang, Shu-Hui Sun, Min-Hua Shao

Journal of Electrochemistry

Single atom catalysts (SAC) have been regarded as the promising alternatives to platinum group metals due to their low costs and potentially high catalytic activities in various electrocatalytic reactions. The atomic mechanism understanding of activity discrepancy among different metal and nitrogen co-doped carbon-based catalysts is still lacking. Here, non-precious metal and nitrogen co-doped carbons (Me-N-C, Me = Fe and Co) as the model catalysts are investigated by combining experimental and theoretical studies to explore the catalytic activities and corresponding reaction mechanisms toward oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) at universal pHs. Atomic theoretical simulations suggest that Fe-N-C …

Application Of Atomically Precise Metal Nanoclusters In Electrocatalysis, Zhi-Hua Zhuang, Wei Chen

Journal of Electrochemistry

Metal nanoclusters (M NCs) consist of only several to a few hundred of metal atoms and possess core sizes less than 2 nm. Owing to the quantum size effect, the electronic states of M NCs evolve to discrete levels similar to the molecule energy gaps, other than a continuous density of states to produce plasmon characteristic of bulk metal nanoparticles (M NPs). In comparison with the conventional M NPs, M NCs exhibit dramatically unique electronic and optical properties, such as molecule-like energy gaps, strong photoluminescence and high catalytic properties, which make them promising for potential application in numerous fields, such …

Electrochemical Surface-Enhanced Raman Spectroscopic Studies On Nickel Ultramicroelectrode, Li-Wen Wu, Wei Wang, Yi-Fan Huang

Journal of Electrochemistry

Nickel (Ni) electrodes are widely used in electrochemical researches. Understanding electrochemical processes on Ni electrodes through in-situ characterization of adsorbed species on their surfaces is helpful for rational optimization and application of Ni electrochemistry. Microelectrochemical surface-enhanced Raman spectroscopy (μEC-SERS) combines the mass transfer feature of ultramicroelectrode with high-sensitivity characterizations of molecular structures, which is a powerful method for studying Ni electrochemistry on polarization and non-equilibrium conditions. The key point of performing μEC-SERS is to make a SERS-active Ni ultramicroelectrode.
Here, we demonstrate a method of preparing a SERS-active Ni ultramicroelectrode through electrochemical deposition of several atomic layers of …

Electrochemical Gating Single-Molecule Circuits With Parallel Paths, Jun-Qing Su, Yi-Fan Zhou, Ling Tong, Ya-Hao Wang, Ju-Fang Zheng, Jing-Zhe Chen, Xiao-Shun Zhou

Journal of Electrochemistry

Electrochemical gating has emerged as a feasible and powerful method to tune single-molecule conductance. Herein, we demonstrate that the electron transport through single-molecule circuits with two benzene rings in parallel could be efficiently gated by electrochemistry. The molecular junctions with two parallel paths are fabricated with Au electrodes by STM break junction (STM-BJ) technique. Their conductance value exhibits a 2.82-fold enhancement by the constructive quantum interference compared to single-molecule junctions with single path for electron tunneling. Furthermore, the conductance of para-benzene based molecule could be electrochemically tuned with a modulation ratio of about 333%·V^-1. With the help of …

Preface To The Special Issue Of The Journal Of Electrochemistry Celebrating 100 Years Of Chemistry At Xiamen University, Chang-Jian Lin, Shi-Gang Sun

Journal of Electrochemistry

No abstract provided.

Luminol/Sulfamic Acid Electrochemiluminescence And Its Application For Dopamine Detection, Tesfaye Hailemariam Barkae, Mohamed Ibrahim Halawa, Tadesse Haile Fereja, Shimeles Addisu Kitte, Xian-Gui Ma, Ye-Quan Chen, Guo-Bao Xu

Journal of Electrochemistry

Herein, sulfamic acid (SA) was utilized, for the first time, to enhance significantly the luminol electrochemiluminescence (ECL). With the SA concentration increased from 0.1 μmol·L^-1 to 500 μmol·L^-1 the ECL intensity increased proportionally. The developed luminol/SA ECL system was employed to detect dopamine (DA) based on its prominent quenching effect. The Stern-Volmer equation of I_o/I= 1+K_sv[DA] could be applied to express well the quenching mechanism of DA in the luminol/SA ECL system. The calibration plot showed that the increase in the DA concentration from 0.5 to 20 μmol·L^-1 decreased linearly the ECL intensity …

Oxygen-Exposure Induced Rapid Oxidation Of Spiro-Ometad In Cspbibr2 Perovskite Solar Cells, Wei-Guo Wang, Tian Bai, Gao-Fei Xue, Mei-Dan Ye

Journal of Electrochemistry

2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene (Spiro-OMeTAD) is the most widely used hole transport material in perovskite solar cells (PSCs). However, its oxidation in the air takes a long time and results in the attack of perovskite by water. In this regard, we performed the oxidation process of Spiro-OMeTAD in oxygen, where perovskite can be protected from water, guaranteeing the integrity of perovskite. It was demonstrated that the champion Spiro-OMeTAD based CsPbIBr₂ PSCs after oxygen oxidation achieved a 7.19% power conversion efficiency (PCE), showing a higher PCE than 6.29% of the champion device oxidized in air. A series of electrochemical characterization methods were applied …

Lithium Storage Performance Of Hard Carbons Anode Materials Prepared By Different Precursors, Zhen-Lang Liang, Yao Yang, Hao Li, Li-Ying Liu, Zhi-Cong Shi

Journal of Electrochemistry

Hard carbon is one of the most promising anode material for lithium ion batteries (LIBs) owing to its high stability, widespread availability, low-cost, and excellent performance. The electrochemical properties of hard carbon materials depend strongly on the type of precursors. It is, therefore, very important to choose an excellent hard carbon precursor. Polyacrylonitrile, petroleum pitch and peanut shells were used as raw materials to prepare different hard carbon anode materials for LIBs. These hard carbon anode materials were successfully synthesized in two steps. The selected precursor was firstly carbonized at 600℃ for 1 h in argon atmosphere using heating rate …

Pd-Based Electrocatalysts For Oxygen Reduction And Ethanol Oxidation Reactions: Some Recent Insights Into Structures And Mechanisms, Zhi-Peng Wu, Chuan-Jian Zhong

Journal of Electrochemistry

The development of efficient electrocatalysts for applications in fuel cells, including proton-exchange membrane fuel cell (PEMFC) and direct ethanol fuel cell (DEFC), has attracted extensive research attention in recent years. Oxygen reduction reaction and ethanol oxidation reaction are two of the key reactions where the design of active, stable and low-cost electrocatalysts is critical for the mass commercializations of PEMFCs and DEFCs. This challenge stems largely from the limited understanding of the catalyst structures and reaction mechanisms. Progress has been made in investigations of electrocatalysts derived from Pd-based alloy nanomaterials both experimentally and computationally. We highlight herein some of the …

Chemically Resolved Nuclear Spin Relaxation, Megan Sly

Undergraduate Research Conference at Missouri S&T

In Nuclear Magnetic Resonance (NMR) Spectroscopy, the excitation of nuclear spins is used to generate spectra of radiofrequency resonance signals. The signal frequencies are typically used to determine the structure of chemical compounds, while the relaxation of the spins to thermodynamic equilibrium provides useful information about the molecular vicinity of a material. When a chemical compound occurs in different molecular environments, a single resonance signal can have multiple relaxation times. To quantify how much material is in how many different environments, a multi-exponential analysis was developed resolving resonance signals and relaxation times in two-dimensional contour plots. Samples of known resonance …

Amorphous Carbon Aerogels From Xerogel Powders, Daniel Greenan

Undergraduate Research Conference at Missouri S&T

Carbon aerogels are well known for their high surface areas and high porosities. Their applications have been demonstrated in a wide range of areas such as CO2 capture, electrodes for electrochemical cells, etc. They are typically made from pyrolysis of carbonizable polymeric aerogels, which in turn are synthesized via sol-gel methods. Preparation of those polymeric aerogels involves supercritical fluid drying of wet-gels by replacing the pore-filling solvent with liquid CO2 that can be vented off as a gas, thus allowing pores to retain their shape and size. In contrast, here a new alternative route is proposed for the synthesis of …

Structure Formation And Coupling Reactions Of Hexaphenylbenzene And Its Brominated Analog, Jacob D. Teeter, Paulo S. Costa, Christoph Dobner, Mamun Sarker, Alexander Sinitskii, A Enders

Department of Chemistry: Faculty Publications

The on-surface coupling of the prototypical precursor molecule for graphene nanoribbon synthesis, 6,11-dibromo-1,2,3,4-tetraphenyltriphenylene (C₄₂Br₂H₂₆, TPTP), and its non-brominated analog hexaphenylbenzene (C₄₂H₃₀, HPB), was investigated on coinage metal substrates as a function of thermal treatment. For HPB, which forms non-covalent 2D monolayers at room temperature, a thermally induced transition of the monolayer’s structure could be achieved by moderate annealing, which is likely driven by π-bond formation. It is found that the dibrominated carbon positions of TPTP do not guide the coupling if the growth occurs on a substrate at temperatures that …

Using Tattoo Inks To Develop Undergraduate General Chemistry And High School Level Chemistry Students’ Understanding Of Atomic Emission, Emma Horoszewski

Undergraduate Honors Theses

An effective way to promote student engagement in the laboratory is to substitute traditional reagents for recognizable, real-world products. In this work, two laboratory experiments are outlined – one geared toward undergraduate general chemistry students and one for high school introductory level chemistry students – which replace solutions of metal salts with tattoo inks in the classic flame test experiment. The main objective of both experiments is to familiarize students with the subatomic mechanism occurring during atomic emission. Additionally, the undergraduate level experiment features the use of spectroscopy to identify metals present within tattoo inks through analysis of atomic emission …

Adhering Homogeneous Molecular Electrocatalysts Entrapped In Micelles To Electrode Surfaces, Emily Kuhlmann

Honors Theses

Heterogeneous catalysts are important to industrial use; however, mechanistic studies are difficult because they lack the easy tunability of homogeneous catalysts. One solution could be to immobilize homogeneous catalysts using micelles while maintaining catalytic properties and activities.

006— Pretreatment And Fiber Content Analysis Of Cannabis Sativa, Dina Bu, Jessica Roggie, Sarah Schmidlin, Barnabas Gikonyo

GREAT Day Posters

Cannabis sativa commonly known as hemp is one of the fastest-growing plants whose refined products have immense commercial value. Various products include refined hemp such as: biofuels, biodegradable plastics, textiles, dietary supplements, paper, clothing, and much more. Hemp fibers are also used in construction and manufacturing applications by strengthening their composite products. Hemp is a high yielding, sustainable, and environmentally friendly crop due to its various qualities, and has the potential to yield valuable raw materials for a great number of applications. Our research evaluates the pretreatment of hemp as well as the comparative analysis of the fiber content thereof. …

041— Fiber Decomposition And Pretreatment Analysis Of Cannabis Sativa L.: Hemp, Dina Bu, Jessica Roggie, Sarah Schmidlin, Barnabas Gikonyo

GREAT Day Posters

Hemp is a subspecies of Cannabis sativa L. along with marijuana, yet the two differ in chemical constituent levels of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Hemp contains 0.3% THC, compared to marijuana 17.1%, allowing it to be a safe and compelling biomass for investigation. The refined products of hemp are vast due to its fast-growing properties; therefore various commercial industries have included refined hemp in biofuels, biodegradable plastics, textiles, dietary supplements, paper, clothing, and much more. Construction and manufacturing applications have also been seen to include hemp to strengthen their composite products. The high-yielding, sustainable, and environmentally friendly qualities …

062— Nano-Size Dependence In Aggregation Process Of Beta 2 Microglobulin Coated Gold Colloids, Kaylee A. Hausrath

GREAT Day Posters

The formation of the aggregates of the beta 2 microglobulin (b2m) coated nano-gold colloids were investigated for various nanogold colloid sizes ranging between 10 nm and 100 nm. The aggregation process was considered to be initiated by the selfassembly of b2m by transforming the folded to the unfolded structure under highly acidic condition (pH < 4). The formation of the aggregates were monitored by a peak shift of surface plasmon resonance (SPR) band as a function of number of free b2m available. As for relatively smaller size of gold colloid diameter a gradual aggregation process was observed. The size of the aggregates was considered to increase monotonically as the b2m was added. On the other hand, as for relatively larger diameter of gold colloid, stepwise aggregation process was observed. So that the aggregates of a particular size was formed at a certain threshold of the concentration of available free b2m. The majority of the gold surface of the smaller gold size was easily covered and support the aggregation even at the lower concentration of b2m.

Patch Testing With Aluminium Finn Chambers Could Give False-Positive Reactions In Patients With Contact Allergy To Aluminium, Lisbeth Rosholm Comstedt, Jakob Dahlin, Magnus Bruze, Yolanda S. Hedberg, Mihály Matura, Cecilia Svedman

Chemistry Publications

Background

Earlier laboratory studies have shown that sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride trigger the release of aluminium (Al) from Finn Chambers (FC).

Objectives

To investigate whether aluminium realease from FC could influence the diagnostic outcome of patch testing with FC.

Method

A retrospective analysis of patch test results from 2010 to 2019 was performed. A two-sided Fisher's exact test was used to calculate any overrepresentation of contact allergy to Al among patients with positive reactions to sodium tetrachloropalladate, Myroxylon pereirae, caine mix II, and palladium chloride.

Results

A total of 5446 patients had been tested …

Experimental And Theoretical Investigation Of Regioselectivity For A Series Of Ketoimines With Nuclear Magnetic Resonance Spectroscopy And Density Functional Theory, Amanda Stahl, Joseph M. Fritsch, Kelsey R. Brereton

Seaver College Research And Scholarly Achievement Symposium

A series of ketoimines bearing pendant quinolyl substituents were prepared by Schiff base condensation of 1,3-diketones with two different substituents: trifluoromethyl and an alkyl/aryl group (e.g., Me, Et, ⁱPr,^tBu, Ph. Synthetic reactions of ketoimines with varying alkyl/aryl substituents altered the distribution of regioisomers as measured in isolated yields and detected by ¹H and ¹⁹F NMR spectroscopy of crude reaction mixtures. Reaction with the least sterically encumbered diketone (CF₃with Me) resulted in mixture of ketoimines with virtually quantitative formation of the ketoimine resulting from quinolyl addition to the carbonyl adjacent to the alkyl substituent. …

Synthesis Of Halogenated Glyoximes, Nickie Tiwari

Honors Theses

Dr. Huang is a chemical engineering professor at the University of Alabama. He is interested in using alpha-Halogenated glyoximes to better understand impurity incorporation of organic additives. Various alpha-Halogenated glyoximes are being synthesized for his study. In this project, bromodimethylglyoxime is being synthesized. This is a two-step reaction. The first reaction converts diacetlymonoxime to bromodimethylglyoxalmonoxime through bromination. The product is then reacted with hydroxylammonium chloride to form bromodimethylglyoxime. Ultimately, there has been success in forming bromodimethylglyoxalmonoxime. For this reaction, solvent ratios of methanol must be proportional to literature values. However, there have been difficulties in converting bromomonoxime to bromodimethylglyoxime. There …