Chemistry Commons^™

Faster Intercalation Pseudocapacitance Enabled By Adjustable Amorphous Titania Where Tunable Isomorphic Architectures Reveal Accelerated Lithium Diffusivity, Wessel Van Den Bergh, Taylor Larison, Maximilliano Jesus Jara Fornerod, Prof. Stefan Guldin, Morgan Stefik

Faculty Publications

Intercalation pseudocapacitance is a faradaic electrochemical phenomenon with high power and energy densities, combining the attractive features of capacitors and batteries, respectively. Intercalation pseudocapacitive responses exhibit surface-limited kinetics by definition, without restriction from the collective of diffusion-based processes. The surface-limited threshold (SLT) corresponds to the maximum voltage sweep rate (vSLT) exhibiting a predominantly surface-limited current response prior to the onset of diffusion-limitations. Prior studies showed increased lithium diffusivity for amorphous titania compared to anatase. Going beyond prior binary comparisons, here a continuum of amorphous titania configurations were prepared using a series of calcination temperatures to tailor both amorphous …

In Situ Recording Of Mars Soundscape, S. Maurice, B. Chide, N. Murdoch, R. D. Lorenz, D. Mimoun, R. C. Wiens, A. Stott, X. Jacob, T. Bertrand, F. Montmessin, N. L. Lanza, C. Alvarez-Llamas, Stanley M. Angel, M. Aung, J. Balaram, O. Beyssac, A. Cousin, G. Delory, O. Forni, T. Fouchet, Et. Al.

Faculty Publications

Before the Perseverance rover landing, the acoustic environment of Mars was unknown. Models predicted that: (1) atmospheric turbulence changes at centimetre scales or smaller at the point where molecular viscosity converts kinetic energy into heat1, (2) the speed of sound varies at the surface with frequency^2,3 and (3) high-frequency waves are strongly attenuated with distance in CO₂ (refs.^2,3,4). However, theoretical models were uncertain because of a lack of experimental data at low pressure and the difficulty to characterize turbulence or attenuation in a closed environment. Here, using Perseverance …

Sustainable Polymers: Upcycling Poly(Vinyl Chloride) And Mimicking Low Density Polyethylene, Ian Baxter

Theses and Dissertations

In this research, increasing the sustainability of polymers was investigated through two main methods. The upcycling of poly(vinyl chloride) and the creation of polymer mimics to create degradable low-density polyethylene. In the first chapter, an overview of the sustainability issues of polymers is presented and approaches are described on how their sustainability may be increased through the upcycling of polymers or the synthesis of degradable polymers that mimic the properties of petrol-based polymers.

Chapter 2 contains the progress on the upcycling of PVC using high oleic soybean oil. Soybean oil can soften PVC making it less brittle than pure PVC. …

Photophysics And Electronic Properties Of Photochromic Metal-Organic Frameworks, Corey R. Martin

Theses and Dissertations

Modulation of materials properties through light-based illumination has the capability to expand the technology sector due to stimuli-responsive dynamic behavior that cannot be achieved in traditional materials. For example, reversibly tuning photophysical profiles of such materials allows for switching between discrete states that is a key aspect for the developing logic gates, spatially- and temporally-resolved sensors, and on-demand drug delivery systems. My efforts have focused on employment of metal-organic frameworks (MOFs) as a versatile platform for the material development which contain photochromic moieties allowing for tailoring their electronic properties. Our group has expanded this direction to include heterometallic and actinide-containing …

Well–Defined Donor–Acceptor Materials, Gabrielle A. Leith

Theses and Dissertations

The modularity of multivariant scaffolds such as covalent–organic frameworks (COFs) provides an unprecedented level of control in the alignment of donor (D) and acceptor (A) units, a demand that is driven by the production of optoelectronic, photonic, and spintronic devices. The foray into novel motifs bearing D-A ensembles in frameworks has been applied towards material property modulation for device performance enhancement. This dissertation presents an emerging trend in the development of D-A interfaces by highlighting recent advances probing D-A interactions in porous crystalline matrices and co-crystals, with a focus on energy transfer (ET) and charge transfer (CT) processes in pre-designed …

Metal Free Bond Activation By Carboranyl Phosphines, Gayathri B. Gange

Theses and Dissertations

In the past few decades, main group-based catalysts have attracted increasing attention as an alternative approach to overcome the most prevailing issues of transition metal catalysts such as high cost, toxicity, and low abundance. Among these main groupbased catalysts, Phosphine based compounds have shown a variety of bond activations due to the strong nucleophilicity from their congener species. To the contrary, unique electron deficient boron-based clusters have the tendency to accept two electrons reversibly due to their electron deficiency. In this study, we have synchronized the electron donor ability of the phosphine with the electron acceptor ability of the ortho …

Synthesis Of Carborane Pincer Complexes And Exploration Of The Reactivity Of Metal-Boron Bonds, Hindurangalage Don Asela Chathumal Jayaweera

Theses and Dissertations

Exploration of transition metal complexes with metal-boron bonds for the cooperative bond activation of small molecules in catalysis is one of the recent developments in novel synthetic strategies. The use of boron clusters as a modular platform for the formation of metal-boron bond has been successfully utilized by our and other groups. Carboranes are icosahedral boron-carbon molecular clusters that have gained attraction as multifunctional ligands due to their unique geometry, electronic properties, and versatility of functionalization methods. Their 3-D structure exerts a steric bulk around the exohedral substituent, either metal or non-metal center. Furthermore, due to the cluster geometry, five …

Tailored Nanomaterials For Advancing Fast-Charge Research, Wessel Van Den Bergh

Theses and Dissertations

The demand for fast, energy-dense storage has driven research into nanoscale intercalation materials. Nanoscale materials not only accelerate kinetics but also can modify reaction path thermodynamics, intercalant solubility, and diffusivity. Pioneering works have revealed such nanoscale changes, often without the need to separately probe each fundamental transport process. While electrodes can be designed to have one transport processes dominant, there remain opportunities to better understand energy-dense designs with multiple concomitant transport constraints. The contents herein highlight emerging an method using tailored, energy-dense nanomaterials and the process of elimination to clearly correlate architectural features to performance. For example, this method revealed …

Adsorption Of Microcystins To Sediment Affects Their Bioavailability And Remediation, Ashley Womer

Theses and Dissertations

The freshwater harmful algae Microcystis spp produces a family of toxins called microcystins1. These species of algae are known to release microcystins from their cells directly into the surrounding water2. This creates an array of human health risks depending on the fate and transport of the toxins in the water column3,4. Risk modelling and previous literature has shown that sediment is a sink for free microcystin, microcystin can be stably adsorbed to sediment for hundreds of years, and its adsorption to sediment is determined by the sediment adsorption partitioning coefficient (Kd)5,6,7. In this work it is hypothesized that the sediment …

Mechanistic Understanding Of Catalytic Processes For Sustainable Chemical Transformations, Pooja J. Ayare

Theses and Dissertations

The current field of catalysis is notably advanced in terms of both conceptual and technical innovation. There is a constant need to design new catalysts and develop catalytic processes to improve the scope, efficiency, and selectivity of various chemical transformations. It is also imperative to design catalytic systems which are effective, truly-recyclable and energy efficient for a sustainable future. This can be done through comprehensive knowledge and understanding of catalyst behavior, reaction kinetics and process designing.

For most industrial processes, the preferred catalysts are heterogeneous because these solid catalysts can be easily separated from the final product. However, they often …

A Comparative Study Of Two Nickel-Based Suzuki-Miyaura Hybrid Molecular Catalysts, Mollie Morrow

Senior Theses

Two molecular nickel-based catalysts, (2,2’bipyridine-4,4’-carboxylic acid)nickel(II) chloride and (2,2'-bipyridine-4,4'-diamidopropylsilatrane)nickel(II) chloride, were synthesized and subsequently attached to a solid support in the form of amorphous silicon dioxide to create two hybrid molecular/heterogeneous catalysts. Characterization using ICP-MS and ATR-FTIR confirms that both catalysts are bonded to the SiO₂ support. The catalysts were both able to catalyze a Suzuki-Miyarua cross-coupling which their molecular counterparts were unable to; the carboxylate catalyst was able to achieve yields of 10% and the silatrane catalyst achieved yields of up to 50%. Post-reaction analysis indicated that while some catalyst desorption occurred in both complexes, active catalytic species …

Modification Of Active Sites In Catalytic Materials For Gas-Phase Heterogeneous Catalysis, Deependra Man Shakya

Theses and Dissertations

Heterogeneous catalysis remains at the core of chemical manufacturing industries with 80-90 % of chemical processes relying on the use of catalysts. Unlike homogeneous catalyst that has extremely well-defined active sites, active sites in heterogeneous catalysis are complex and show dynamic behavior under reaction conditions, and change their structures, composition, particle size. The complexity associated with these systems has made the rational design of the catalyst a difficult problem. Highly crystalline metalorganic frameworks (MOFs) as heterogeneous catalysts present the unique opportunity to systematically modify the geometries, ensemble sizes, and compositions of highly dispersed active sites due to their tailorable, and …

One Planet: One Health. A Call To Support The Initiative On A Global Science-Policy Body On Chemicals And Waste, Werner Brack, Damia Barcelo Culleres, Alistair B.A. Boxall, Helene Budzinski, Sara Castiglioni, Adrian Covaci, Valeria Dulio, Beate I. Escher, Peter Fantke, Faith Kandie, Despo Fatta-Kassinos, Felix J. Hernandez, Klara Hilscherova, Juliane Hollender, Henner Hollert, Annika Jahnke, Barbara Kasprzyk-Hordern, Stuart J. Khan, Andreas Kortenkamp, Klaus Kuemmerer, Brice Lalonde, Marja H. Lamoree, Yves Levi, Pablo Antonio Lara Martin, Cassiana C. Montagner, Christian Mougin, Titus Msagati, Joerg Oehlmann, Leo Posthuma, Malcolm Reid, Martin Reinhard, Susan D. Richardson, Et. Al.

Faculty Publications

The chemical pollution crisis severely threatens human and environmental health globally. To tackle this challenge the establishment of an overarching international science–policy body has recently been suggested. We strongly support this initiative based on the awareness that humanity has already likely left the safe operating space within planetary boundaries for novel entities including chemical pollution. Immediate action is essential and needs to be informed by sound scientific knowledge and data compiled and critically evaluated by an overarching science–policy interface body. Major challenges for such a body are (i) to foster global knowledge production on exposure, impacts and governance going beyond …

Intramolecular Friedel-Crafts Addition Of Indoles To Tertiary Allylic Alcohols, Bryan H. Wakefield, Romie Barnes, Traeannah Brown, Ashley M. Jones, Victoria A. Knotts, Christina Martinetti

Journal of the South Carolina Academy of Science

An intermolecular Friedel-Crafts alkylation of indole and tertiary allylic alcohols has been developed. The allylic alcohols were synthesized using a two-step procedure, then exposure of these alcohols to diphenyl phosphate facilitated the desired annulation reaction. This reaction tolerated a variety of indole substitutions to yield 1H,2H,3H,4H-pyrido[1,2-a]indoles.

Amorphization Of Pseudocapacitive T−Nb2O5 Accelerates Lithium Diffusivity As Revealed Using Tunable Isomorphic Architectures, Wessel Van Den Bergh, Sean Wechsler, Hasala Nadeesini Lokupitiya, Lauren Jarocha, Kwangnam Kim, James Chapman, Kyoung E. Kweon, Brandon C. Wood, Steve Heald, Morgan Stefik Phd

Faculty Publications

Intercalationpseudocapacitancecan combinecapacitor-likepower densitieswith battery-likeenergy densities.Such surface-limitedbehaviorrequiresrapid diffusionwhere amorphizationcan increasesolid-statediffusivity.Here intercalationpseudoca-pacitivematerialswith tailoredextentsof amorphizationin T-Nb2O5are first reported.Amorphizationwas characterizedwithWAXS, XPS, XAFS, and EPR which suggesteda peroxide-rich(O22) surface that was consistentwith DFT predictions.A seriesof tunableisomorphicarchitecturesenabledcomparisonswhileindependentlyvaryingtransportparameters.Throughprocessof elimination,solid-statelithium diffusionwas identifiedas thedominantdiffusive-constraintdictatingthe maximumvoltagesweep rate for surface-limitedkinetics(vSLT), termed the Surface-LimitedThreshold(SLT). ThevSLTincreasedwith amorphizationhoweverstable cycling requiredcrystallineT-Nb2O5. A current-responsemodel using series-impedanceswell-matchedtheseobservations.This perspectiverevealedthat amorphizationof T-Nb2O5enhancedsolid-statediffusionby 12.2% and increasedsurface-limitationsby 17.0% (stablesamples).This approachenabledretaining95% lithiationcapacityat ~800mVs1(1,600C-rate equivalent).

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 …

Single-Variable Porous Nanomaterial Series From Polymer Structure-Directing Agents, Morgan Stefik

Faculty Publications

Block polymer structure-directing agents (SDA) enable the production of porous nanoscale materials. Most strategies rely upon polymer equilibration where diverse morphologies are realized in porous functional materials. This review details how solvent selectivity determines the polymer SDA behaviors, spanning from bulk-type to solution-type. Equilibrating behavior of either type, however, obscures nanostructure cause-and-effect since the resulting sample series convolve multiple spatial variations. Solution-type SDA behaviors include both dynamic and persistent micelles. Persistent micelle templates (PMT) use high solvent selectivity for kinetic entrapment. PMTs enable independent wall thickness control with demonstrated 2 Å precision alterations. Unimodal PMT pore size distributions have spanned …

Spectroscopic Studies Of The Interaction Between Phosphorus Heterocycles And Cytochrome P450, Dumei Ma, Libo Zhang, Yingwu Yin, Yuxing Gao, Qian Wang

Faculty Publications

P450 fatty acid decarboxylase OleT from Staphylococcus aureus (OleT_SA) is a novel cytochrome P450 enzyme that catalyzes the oxidative decarboxylation of fatty acids to yield primarily terminal alkenes and CO₂ or minor α- and β-hydroxylated fatty acids as side-products. In this work, the interactions between a series of cycloalkyl phosphorus heterocycles (CPHs) and OleT_SA were investigated in detail by fluorescence titration experiment, ultraviolet–visible (UV–vis) and ³¹P NMR spectroscopies. Fluorescence titration experiment results clearly showed that a dynamic quenching occurred when CPH-6, a representative CPHs, interacted with OleT_SA with a binding constant value of 15.2 …

Teaching An Old Dog New Tricks: Synthesis And Applications Of Novel Polybenzimidazole (Pbi) Membranes, Laura Ann Murdock

Theses and Dissertations

Polybenzimidazoles (PBIs) represent a class of performance polymers that display exceptional thermal and oxidative stability. For almost thirty years, PBI membranes have been investigated as promising candidates for next-generation alternative energy devices, including high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) and vanadium redox flow batteries (VRBs). Issues with the production of PBI membranes arise from their inherent low solubility in organic solvents. Thus, conventional approaches typically yield membranes that have limited molecular weight and generate significant waste in preparation, due to the large quantity of solvent required to dissolve PBIs for membrane casting.

Presented herein is the development of …

Enhancing Charge Carrier Mobility In Colloidal Quantum Dots For Technological Applications, Fiaz Ahmed

Theses and Dissertations

Colloidal quantum dots (QD) are promising semiconducting materials to engineer photovoltaic and optoelectronic devices due to tunable size-dependent absorption and emission properties. These materials are important as they don’t need complicated equipment and huge setup investment for industrial applications. If formulated into a kind of stable nano-ink, these QDs can be incorporated into devices using the most economical processing technologies, spray or roll to roll printing. More importantly, these are compatible with thin-film stacked devices and circuitry that can be formed on heat-sensitive and flexible substrates to make flexible wearable devices and sensors that are difficult to achieve with crystalline-based …

From Persistent Radicals To Conductivity: A Structure Property Investigation In A Series Of Urea-Tethered Halogenated Triphenylamines, Muhammad Saddam Hossain

Theses and Dissertations

Triphenylamines (TPAs) are known to form persistent organic radicals either by chemical, electrochemical or photoinduced oxidation. Typically, fully para-substituted TPAs form stable radical cations while the radical cations in partially substituted systems quickly degrade. Herein, we study the effects of solid-state organization on a series of urea tethered halogenated TPAs 1 (X = H, Cl, Br, I) and compare their radical cation formation and persistence after UV-irradiation. These halogenated urea tethered TPAs were examined by single-crystal X-ray diffraction where their assembly was guided by threecentered urea hydrogen bonding interaction. As expected, all compounds form photogenerated radical cations in solution, but …

Investigations On The Surface Chemistry Of Colloidal Quantum Dots Towards Fluorescent Biological Probes, John Hardin Dunlap

Theses and Dissertations

Colloidal semiconductor quantum dots (QDs) have garnered significant interest as promising materials for biological applications due to their improved photostability and narrow, tunable photoluminescence properties compared to organic fluorophores. To facilitate their utility as fluorescent bioimaging probes, QDs must undergo post-synthetic modifications to exchange their native hydrophobic ligands from synthesis with hydrophilic ones that enable colloidal dispersions in aqueous environments. Many examples exist that demonstrate surface modifications for water-soluble QDs and their efficacy in biological systems, however, there is a need to develop a more thorough understanding of how hydrophilic ligands coordinate to QD surfaces in order to develop more …

Developing Covalent-Organic Frameworks For Protecting Against Radiation, Megan J. Francis

Senior Theses

This research focuses on the development of lightweight, thermostable dual-function materials for secondary radiation protection and sensing by the integration of hydrogen-rich aliphatic chains inside the porous matrix of covalent-organic frameworks (COFs). The main aims of this project are the synthesis of organic linkers for forming a robust porous COF, synthesizing the porous COF through a condensation reaction, the development of hydrogen-rich aliphatic chains, and integration of aliphatic chains into COFs through click chemistry. This manuscript outlines the methodology and development of a novel self-assembled crystalline, porous material engineered to combine the functions of a shield and sensitive dosimeter. The …

Investigating The Chemistry Of Harmful Algal Blooms And Microbial Communities In The Natural Environment, Samuel Patrick Putnam

Theses and Dissertations

Cyanobacteria has existed on the planet for over 3 billion years, and as technology, science, and industry have allowed us to shape our world, these changes have caused a proliferation of biomass. Higher carbon dioxide levels in the atmosphere, warmer temperatures, and rapid increases in the nutrient cycle have created excellent growing conditions for cyanobacteria, making them endemic in fresh waters throughout the world. The work in this dissertation was directed towards the secondary metabolites produced by cyanobacteria and other surrounding microbes and understanding their concentrations and release in natural systems. Analytical methods were developed for the extraction and quantification …

Characterization Of A Novel Fe-S Cluster Transfer Pathway Between Grx4 And Sufa In Escherichia Coli, Enis Sanchez

Theses and Dissertations

Biogenesis of iron-sulfur (Fe-S) clusters is an essential process in living organisms due to the critical role of Fe-S cluster proteins in a myriad of cellular functions. During the assembly of Fe-S clusters, multi-protein complexes are used to drive the mobilization and protection of reactive sulfur and iron intermediates, regulate assembly of various Fe-S clusters on an ATPase-dependent, multi-protein scaffold, and target nascent clusters to their downstream protein targets. In each of the Fe-S cluster biogenesis steps, specific protein-protein interactions (PPIs) are required for proper function of the assembly pathway. The target pathway is the sulfur formation (Suf) pathway for …

Polymeric Sorbents For Solid-Phase Extraction (Spe) Of Polar Analytes And Carbon Dioxide Capture, Ishwor Karki

Theses and Dissertations

The main topics of this dissertation are: 1) the study of hydrophilic-lipophilic balance (HLB) polymer monoliths for solid-phase extraction (SPE) applications, 2) molecularly imprinted polymers (MIPs) for capturing the CO2 gas and 3) the application of symmetry-adapted perturbation theory (SAPT) calculations to examine the origins of non-covalent interactions.

HLB polymers are popular sorbent materials in separation science. The Divinylbenzene-co-N-vinylpyrrolidone (DVB-co-NVP) polymer is one of the most widely used general-purpose HLB polymers. Despite the popularity of HLB polymer stationary phases, the studies of the adsorption properties of DVB-co-NVP have only been reported over a narrow …

Optimization And Application Of Electrochemical Probes For Neurotransmitter Detection, Colby E. Witt

Theses and Dissertations

The brain is a complex matrix that is difficult to study. Signaling molecules, neurotransmitters, are constantly being released and sequestered back into neurons within milliseconds to facilitate communication and normal function, a process called neurotransmission. There are few analytical techniques available to selectively probe such a dynamic system, and even fewer can detect these discrete changes in real-time. In order to make robust measurements in the brain you need speed, sensitivity, selectivity and small probe size, which are encompassed by fast-voltammetry with microelectrodes. Traditional fast-voltammetry at carbon fiber microelectrodes (fast-scan cyclic voltammetry (FSCV)) requires background subtraction to overcome the large …

Fe-Catalyzed Sulfide Oxidation In Hydrothermal Plumes Is A Source Of Reactive Oxygen Species To The Ocean, Timothy J. Shaw, George W. Luther Iii, Richard Rosas, Véronique E. Oldham, Nicole R. Coffey, John L. Ferry, Dewamunnage M. C. Dias, Mustafa Yücel, Aubin Thibault De Chanvalon

Faculty Publications

Historically, the production of reactive oxygen species (ROS) in the ocean has been attributed to photochemical and biochemical reactions. However, hydrothermal vents emit globally significant inventories of reduced Fe and S species that should react rapidly with oxygen in bottom water and serve as a heretofore unmeasured source of ROS. Here, we show that the Fe-catalyzed oxidation of reduced sulfur species in hydrothermal vent plumes in the deep oceans supported the abiotic formation of ROS at concentrations 20 to 100 times higher than the average for photoproduced ROS in surface waters. ROS (measured as hydrogen peroxide) were determined in hydrothermal …

Small Studies, Big Decisions: The Role Of Pilot/Feasibility Studies In Incremental Science And Premature Scale-Up Of Behavioral Interventions, Michael William Beets, Lauren Von Klinggraeff, Robert G. Weaver, Bridget Ryan Armstrong, Sarah Burkart

Faculty Publications

Background: Careful consideration and planning are required to establish “sufficient” evidence to ensure an investment in a larger, more well-powered behavioral intervention trial is worthwhile. In the behavioral sciences, this process typically occurs where smaller-scale studies inform larger-scale trials. Believing that one can do the same things and expect the same outcomes in a larger-scale trial that were done in a smaller-scale preliminary study (i.e., pilot/feasibility) is wishful thinking, yet common practice. Starting small makes sense, but small studies come with big decisions that can influence the usefulness of the evidence designed to inform decisions about moving forward with a …

Table Of Contents

Journal of the South Carolina Academy of Science

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