Chemistry Commons^™

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 …

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 …

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 …

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 …

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 …

Mobile Protons Limit The Stability Of Salt Bridges In The Gas Phase: Implications For The Structures Of Electrosprayed Protein Ions., Lars Konermann, Elnaz Aliyari, Justin H Lee

Chemistry Publications

Electrosprayed protein ions can retain native-like conformations. The intramolecular contacts that stabilize these compact gas-phase structures remain poorly understood. Recent work has uncovered abundant salt bridges in electrosprayed proteins. Salt bridges are zwitterionic BH⁺/A^- contacts. The low dielectric constant in the vacuum strengthens electrostatic interactions, suggesting that salt bridges could be a key contributor to the retention of compact protein structures. A problem with this assertion is that H⁺ are mobile, such that H⁺ transfer can convert salt bridges into neutral B⁰/HA⁰ contacts. This possible salt bridge annihilation puts into question the …

Surface Functionalization Of Elastomers For Tunable Crystal Growth And Smart Adhesives, John Kapitan

Department of Chemistry: Dissertations, Theses, and Student Research

Silicone rubbers have seen extensive work on modulation of their surface environments for use in microfluidics, cell adhesion, and sensing. Most surface procedures utilize a common initial step of oxidation of the surface to increase the number of active surface functional groups. Following oxidation more permanent functionalities can be imparted on the surface using silanization, grafting polymer brushes, or creating ionic bonds to the surface. Of these three, silanization proves to be the most pervasive due to the range of procedures available and how easy the procedures prove to be. However, the mechanism by which silanization is performed heavily involves …

Sf6+: Stabilizing Transient Ions In Helium Nanodroplets, Simon Albertini, Stefan Bergmeister, Felix Laimer, Paul Martini, Elisabeth Gruber, Fabio Zappa, Milan Ončák, Paul Scheier, Olof E. Echt

Faculty Publications

There are myriads of ions that are deemed too short-lived to be experimentally accessible. One of them is SF₆⁺. It has never been observed, although not for lack of trying. We demonstrate that long-lived SF₆⁺ can be formed by doping charged helium nanodroplets (HNDs) with sulfur hexafluoride; excess helium is then gently stripped from the doped HNDs by collisions with helium gas. The ion is identified by high-resolution mass spectrometry (resolution m/Dm = 15000), the close agreement between the expected and observed yield of ions that contain minor sulfur isotopes, and collision-induced dissociation …

Parallel Computation Of Feynman Path Integrals And Many-Body Polarization With Application To Metal-Organic Materials, Brant H. Tudor

USF Tampa Graduate Theses and Dissertations

The Space Research Group is a computational outfit, and so the work presented herein will reflect that. Much of our simulation code is developed in-house and so what follows is a small exploration of that development—although the physics underpinning our software development is never ignored for long. Following the programming centric work, the code and the physics are put to the test. The final chapter describes a scientific endeavor in which a new, robust force field has been validated. Indeed, the new potential has taken a first step in proving itself by making accurate predictions in what have historically found …

The Interconnectivity Of Parkinson's Disease And Type Two Diabetes Mellitus, Erica Olfson

Honors Scholars Collaborative Projects

This thesis is about the biochemical connection between Parkinson's disease and Type II Diabetes Mellitus.

A Divergent Strategy For The Synthesis Of Redox-Active Verdazyl Radical Polymers, Francois Magnan, Jasveer S. Dhindsa, Michael Anghel, Paul Bazylweski, Giovanni Fanchini, Joe Gilroy

Chemistry Publications

Stable radical polymers have attracted significant attention due to their use as magnetic materials, (co)catalysts in organic synthesis, and as functional components of organic electronics including batteries and memory devices. Despite their importance, a relatively narrow range of synthetic strategies exist for their production. The most common examples involve the transition-metal catalyzed polymerization of radical-containing monomers or the sequential polymerization of monomers containing radical precursors and their post-polymerization conversion to radicals. Post-polymerization installation of stable radicals is not commonly reported. Copper-assisted azide-alkyne cycloaddition (CuAAC) chemistry has seen limited use in this regard, but only for the production of p-conjugated and …

Suppressing Bias Stress Degradation In High Performance Solution Processed Organic Transistors Operating In Air, Hamna F. Iqbal, Qianxiang Ai, Karl J. Thorley, Hu Chen, Iain Mcculloch, Chad Risko, John E. Anthony, Oana D. Jurchescu

Chemistry Faculty Publications

Solution processed organic field effect transistors can become ubiquitous in flexible optoelectronics. While progress in material and device design has been astonishing, low environmental and operational stabilities remain longstanding problems obstructing their immediate deployment in real world applications. Here, we introduce a strategy to identify the most probable and severe degradation pathways in organic transistors and then implement a method to eliminate the main sources of instabilities. Real time monitoring of the energetic distribution and transformation of electronic trap states during device operation, in conjunction with simulations, revealed the nature of traps responsible for performance degradation. With this information, we …

Co-Evolutionary Analysis Suggests A Role For Tlr9 In Papillomavirus Restriction, Kelly King, Brendan B. Larsen, Sophie Gryseeis, Cécile Richet, Simona Kraberger, Robert Jackson, Michael Worobey, Joseph S. Harrison, Arvind Varsani, Koenraad Van Doorslaer

College of the Pacific Faculty Articles

Upon infection, DNA viruses can be sensed by pattern recognition receptors (PRRs) leading to the activation of type I and III interferons, aimed at blocking infection. Therefore, viruses must inhibit these signaling pathways, avoid being detected, or both. Papillomavirus virions are trafficked from early endosomes to the Golgi apparatus and wait for the onset of mitosis to complete nuclear entry. This unique subcellular trafficking strategy avoids detection by cytoplasmic PRRs, a property that may contribute to establishment of infection. However, as the capsid uncoats within acidic endosomal compartments, the viral DNA may be exposed to detection by toll-like receptor (TLR) …

Fluorogenic Probes For Thioredoxin Reductase Activity, Tendai J. Mafireyi, Jorge O. Escobedo, Robert Strongin

Chemistry Faculty Publications and Presentations

The thioredoxin system is vital in maintaining the cellular redox state and is implicated in various cancers and other diseases. It comprises of thioredoxin reductase, thioredoxin and NADPH. Various methods have been developed for the detection and quantification of the thioredoxin reductase enzyme. Most of these methods suffer the shortfall of poor specificity, hence there is need to develop more robust and specific techniques. Recently, there has been an increased interest in fluorescent probes that can target thioredoxin reductase. This review highlights the progress in the synthesis and application of the different fluorescent probes that have been employed for this …

Studies Of The Rectification Behavior Of The Pdt Ligand And The Active Site Of Msrp, Laura J. Ingersol

Chemistry and Chemical Biology ETDs

Molybdenum (Mo) is an essential element that plays an important role in global nitrogen, carbon, and sulfur cycles with a critical role in human metabolism and ecological balance. It becomes catalytically active when complexed with the pyranopterin dithiolene ligand (PDT), forming the nearly ubiquitous molybdenum cofactor (Moco). The complex biosynthetic pathway of Moco, its presence in all three domains of life, and its role as a constituent cofactor in the last universal common ancestor (LUCA) all point toward the importance of the PDT in the development of life on Earth. Molybdoenzymes catalyze the two-electron oxidation or reduction of substrates that …

Direct Detection Of 5-Mev Protons By Flexible Organic Thin-Film Devices, Ilaria Fratelli, Andrea Ciavatti, Enrico Zanazzi, Laura Basiricò, Massimo Chiari, Laura Fabbri, John E. Anthony, Alberto Quaranta, Beatrice Fraboni

Chemistry Faculty Publications

The direct detection of 5-MeV protons by flexible organic detectors based on thin films is here demonstrated. The organic devices act as a solid-state detector, in which the energy released by the protons within the active layer of the sensor is converted into an electrical current. These sensors can quantitatively and reliably measure the dose of protons impinging on the sensor both in real time and in integration mode. This study shows how to detect and exploit the energy absorbed both by the organic semiconducting layer and by the plastic substrate, allowing to extrapolate information on the present and past …

Inhibiting Nitroso Related Methylation Of Guanine Using Dietary Supplements And Flavonoids, Madeline Mccoy, James Davis, Chloe Rippey, Stephen Hobson

Liberty University Research Week

Undergraduate

Basic

Raising Global Awareness And Internationality In The Undergraduate Organic Chemistry Laboratory, Marissa Scilley, Michael R. Korn

Liberty University Research Week

Undergraduate

Applied

Acid Catalyzed Small Ring Alcohols And Alkenes: An Artistic Approach To Visualizing Relationships Between Features Produced By Uv-Visible Spectra, Madeleine Ware

Campus Research Month

Madeleine Ware

Research Description

Campus Research Day

My physical organic chemistry research was supervised by Dr. Mitch Menzmer who studies the formation of carbocation intermediates in acid-catalyzed reactions of alkylated and non-alkylated small ring alcohols. The goal of my work was to compile data and develop methods to search for relationships between the initial structures of molecules analyzed and the wavelengths of maximum absorbance for features observed within a given spectrum. In addition, my advisor from the School of Visual Art and Design, Associate Professor Marc Boyson, contributed to this process by providing insights about the way information could be …