Chemistry Commons^™

Synthesis, Modification, Characterization And Processing Of Molded And Electrospun Thermoplastic Polymer Composites And Nanocomposites, Tamalia Julien

USF Tampa Graduate Theses and Dissertations

This dissertation focuses on the versatility and integrity of a novel, ultrasoft polycarbonate polyurethane (PCPU) by the introduction of nanoparticles and lithium salts. Additionally, the research takes into account the use of electrospinning as a technique to create PCPU and polyimide (PI) fibers. These polymers are of interest as they offer a wide range of properties and uses within the medical and industrial fields.

An industrial batch of an ultrasoft thermoplastic polyurethane (TPU) was synthesized using a two-step process. The first was to create an end capped pre-polymer from methylene bis (4-cyclohexylisocyanate), and a polycarbonate polyol made up of 1,6- …

Synthesis, Characterization, And Assessment Of Cationic Polypeptoids Toward Gene Delivery And Development Of Air Stable N-Substituted N-Thiocarboxyanhydrides, Jessica Michelle Simpson

LSU Doctoral Dissertations

Peptoids are a class of peptidomimetic polymers, which have attracted much attention over the years. Due to their structural similarity to peptides, this group of polymers affords good biocompatibility making them of interest for biomedical applications. This dissertation is largely about the design, synthesis, and characterization of cationic polypeptoids for biological applications, particularly nonviral gene delivery. The dissertation will also cover the development, characterization, and polymerization behavior of a new, air stable N-thiocarboxyanhydride (NTA) monomer.

Introducing functionality, such as small biomolecules and organic compounds can provide distinctive properties to the polymers. Chapter 1 introduces gene therapy and concepts pertinent …

Computational Investigation Of The Ring-Opening Homo- And Co-Polymerizations Of Lactide And Ε-Caprolactone, Diego Garcia, Benjamin Wilson, Joe Fritsch

Seaver College Research And Scholarly Achievement Symposium

The mechanism for the ring-opening polymerization of lactide and ε-caprolactone is presented here with an aluminum-centered catalyst featuring a tridentate ligand and two alkoxide initiating ligands. In each homopolymerization, the addition of electron-withdrawing groups on the tridentate ligand lowers the activation energy of the reaction by increasing the electrophilicity of the central Aluminum. We further investigated the polymerizations by comparing the energy difference between copolymerization and homopolymerization following the initial ring opening as well as the potential for dual polymer chains from the insertion of both initiating ligand. Single chain polymerization is favored in every case, due to lower bond …

Synthesis Of Dimeric Zinc Complexes For Use As Ring Opening Polymerization Catalysts, Kyle D. Brooks, Arnlold Rheingold, David B. Green, Joe Fritsch

Seaver College Research And Scholarly Achievement Symposium

No abstract provided.

Functionalized Nanoporous Carbon Scaffolds For Hydrogen Storage Applications, Christopher Carr

Dissertations

Recent efforts have demonstrated confinement in porous scaffolds at the nanoscale can alter the hydrogen sorption properties of metal hydrides, though not to an extent feasible for use in onboard hydrogen storage applications, proposing the need for a method allowing further modifications. The work presented here explores how the functionalization of nanoporous carbon scaffold surfaces with heteroatoms can modify the hydrogen sorption properties of confined metal hydrides in relation to non-functionalized scaffolds (FS). Investigations of nanoconfined LiBH₄and NaAlH₄indicate functionalizing the carbon scaffold surface with nitrogen can shift the activation energy of hydrogen desorption in excess of …

Halogen, Chalcogen, And Pnicogen Bonding Involving Hypervalent Atoms, Steve Scheiner, Jia Lu

Chemistry and Biochemistry Faculty Publications

The additional substituents arising from hypervalency present a number of complicating issues for the formation of noncovalent bonds. The XF5 molecule (X=Cl, Br, I) was allowed to form a halogen bond with NH3 as base. Hypervalent chalcogen bonding is examined by way of YF4 and YF6 (Y=S, Se, Te), and ZF5 (Z=P, As, Sb) is used to model pnicogen bonding. Pnicogen bonds are particularly strong, with interaction energies approaching 50 kcal/mol, and also involve wholesale rearrangement from trigonal bipyramidal in the monomer to square pyramidal in the complex, subject to a large deformation energy. YF4 chalcogen bonding is also strong, …

Robust Microplate-Based Methods For Culturing And In Vivo Phenotypic Screening Of Chlamydomonas Reinhardtii, Timothy C. Haire, Cody Bell, Kirstin Cutshaw, Brendan Swiger, Kurt Winkelmann, Andrew G. Palmer

Biomedical Engineering and Sciences Faculty Publications

Chlamydomonas reinhardtii (Cr), a unicellular alga, is routinely utilized to study photosynthetic biochemistry, ciliary motility, and cellular reproduction. Its minimal culture requirements, unicellular morphology, and ease of transformation have made it a popular model system. Despite its relatively slow doubling time, compared with many bacteria, it is an ideal eukaryotic system for microplate-based studies utilizing either, or both, absorbance as well as fluorescence assays. Such microplate assays are powerful tools for researchers in the areas of toxicology, pharmacology, chemical genetics, biotechnology, and more. However, while microplate-based assays are valuable tools for screening biological systems, these methodologies can significantly alter the …

Improving Fallout Characterization By Using Multivariate Techniques To Determine Composition, Christopher R. Pitkins

Theses and Dissertations

Multivariate statistical techniques have been applied in order to un-mix nuclear fallout debris chemical data. This information is critical to characterization of fallout particle formation following a nuclear detonation. Understanding the correlation between environmental precursors and actinide concentrations in post-detonation nuclear fallout material aids in understanding the physical and chemical processes that alter nuclear device signatures in the fireball. This research examines 123 nuclear fallout samples from a historical nuclear test. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) are used to collect chemical compositions of the fallout samples. Principal component analysis (PCA) is applied in order to examine …

Design, Synthesis, Application Of Biodegradable Polymers, Mussie Gide

USF Tampa Graduate Theses and Dissertations

Bacterial infections have posed a serious threat to the public health due to the significant rise of the infections caused by antibiotic-resistant bacteria. There has been considerable interest in the development of antimicrobial agents which mimic the natural HDPs, and among them biodegradable polymers are newly discovered drug candidates with ease of synthesis and low manufacture cost compared to synthetic host defense peptides. Herein, we present the synthesis of biocompatible and biodegradable polymers including polycarbonate polymers, unimolecular micelle hyperbranched polymers and dendrimers that mimic the antibacterial mechanism of HDPs by compromising bacterial cell membranes. The developed amphiphilic polycarbonates are highly …

Investigation On The Reactivity Of Tetranuclear Group 7/8 Mixed-Metal Clusters Toward Triphenylphosphine, Md. Rassel Moni, Md. Jadu Mia, Shishir Ghosh, Derek A. Tocher, Shaikh M. Mobin, Tasneem A. Siddiquee, Shariff E. Kabir

Chemistry Faculty Research

Reactions of the tetranuclear mixed-metal clusters ReM3(CO)13(µ3-thpymS) (1, M = Os; 2, M = Ru; thpymSH = tetrahydropyrimidine-2-thiol) with PPh3 are examined. At room temperature reaction between 1 and PPh3 in the presence Me3NO leads to the formation of mono- and bis-phosphine substituted clusters ReOs3(CO)12(PPh3)(µ3-thpymS) (3) and ReOs3(CO)11(PPh3)2(µ3-thpymS) (4). Cluster 3 also reacts with PPh3 under similar conditions to give 4. In contrast, a similar reaction between 2 and PPh3 furnishes only the mono-phosphine substituted clusters ReRu3(CO)12(PPh3)(µ3-thpymS) (3). All the new clusters have been characterized by analytical and spectroscopic data together with single crystal X-ray diffraction for 1, 3 and …

Dynamics Of Singlet Fission And Electron Injection In Self-Assembled Acene Monolayers On Titanium Dioxide, Natalie A. Pace, Dylan H. Arias, Devin B. Granger, Steven Christensen, John E. Anthony, Justin C. Johnson

Chemistry Faculty Publications

We employ a combination of linear spectroscopy, electrochemistry, and transient absorption spectroscopy to characterize the interplay between electron transfer and singlet fission dynamics in polyacene-based dyes attached to nanostructured TiO₂. For triisopropyl silylethynyl (TIPS)-pentacene, we find that the singlet fission time constant increases to 6.5 ps on a nanostructured TiO₂ surface relative to a thin film time constant of 150 fs, and that triplets do not dissociate after they are formed. In contrast, TIPS-tetracene singlets quickly dissociate in 2 ps at the molecule/TiO₂ interface, and this dissociation outcompetes the relatively slow singlet fission process. The addition …

Crown Ether Effects On The Location Of Charge Carriers In Electrospray Droplets: Implications For The Mechanism Of Protein Charging And Supercharging., Haidy Metwally, Lars Konermann

Chemistry Publications

"Native" electrospray ionization (ESI) mass spectrometry (MS) aims to transfer proteins from solution into the gas phase while maintaining solution-like structures and interactions. The ability to control the charge states of protein ions produced in these experiments is of considerable importance. Supercharging agents (SCAs) such as sulfolane greatly elevate charge states without significantly affecting the protein structure in bulk aqueous solution. The origin of native ESI supercharging remains contentious. According to one model, SCAs trigger unfolding within ESI droplets. In contrast, the "charge trapping model" envisions that SCAs impede the ejection of charge carriers (e.g., NH₄⁺ or Na …

De Novo Glycan Sequencing By Electronic Excitation Dissociation And Fixed-Charge Derivatization, Yang Tang, Yi Pu, Jinshan Gao, Pengyu Hong, Catherine E. Costello, Cheng Lin

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

Detailed glycan structural characterization is frequently achieved by collisionally activated dissociation (CAD) based sequential tandem mass spectrometry (MS n ) analysis of permethylated glycans. However, it is challenging to implement MS n (n > 2) during online glycan separation, and this has limited its application to analysis of complex glycan mixtures from biological samples. Further, permethylation can reduce liquid chromatographic (LC) resolution of isomeric glycans. Here, we studied the electronic excitation dissociation (EED) fragmentation behavior of native glycans with a reducing-end fixed charge tag and identified key spectral features that are useful for topology and linkage determination. We also developed a …

Investigating The Synthesis Of 1,3,4-Oxadiazoles Via A Novel Two-Step-One-Pot Cyclodehydration Reaction, Brittney Sowers

Undergraduate Honors Thesis Projects

The given research will investigate synthetic strategies and differential functionalization of 1,3,4- oxadiazoles in hopes of obtaining moderate to high yields. Particularly, the effects of electron withdrawing on oxadiazoles will reveal more information about possible mechanistic details and reaction optimization.

The research in this report is a part of a lager research effort being investigated by Dr. Robin Grote. This research is ongoing and has evolved from its start in the Grote Lab. Previously, the Grote Lab has focused on the formation of a patented heterocycle that contained an amino-pyrazine functional group. Currently, our research has shifted focus to the …

Ultrahigh Resolution Ft-Icr Ms Data For Biomass Burning Emissions-Influenced Fog And Aerosol From The Po Valley, Matthew Brege, Lynn Mazzoleni

Department of Chemistry Publications

This dataset and the methods used to obtain it were described in "Molecular insights on aging and aqueous phase processing from ambient biomass burning emissions-influenced Po Valley fog and aerosol” submitted to Atmospheric Chemistry and Physics in March of 2018. Briefly, two samples of ambient fog water and two samples of ambient aerosol collected in the Po Valley (Italy) during the 2013 Supersito field campaign were analyzed using negative mode electrospray ionization Fourier transform ion cyclotron mass spectrometry (FT-ICR MS). The extent of “fresh” vs. “aged” biomass burning influence was estimated prior to FT-ICR MS analysis using proton nuclear magnetic …

Synthesis And Characterization Of Covalent Adaptable Networks Comprised Of Dynamic Imine And Aminal Covalent Bonds, Albert Chao

LSU Doctoral Dissertations

The dissertation is about the design, synthesis and characterization of materials comprised of covalent adaptable networks (CANs). There are three chapters within this dissertation.

Chapter 1 contains a short overview of conventional thermosets and thermoplastics. A new strategy of combining advantages from thermosets and thermoplastics is utilizing dynamic covalent chemistry (DCC) for material design. Dynamic covalent bonds are able to undergo dynamic exchange which allow the material to adapt to a new state when under stimuli such as stress or strain. Material comprised of such reversible networks is called covalent adaptable networks (CANs). These types of reversible covalent bonds followed …

Polymers Course For Small Colleges And Universities, Joseph Furgal

Chemistry Faculty Publications

This article describes the course design and teaching methodology for a polymer chemistry and applications lecture class specifically aimed at small college and university instruction. This intermediate course for advanced undergraduates and masters level graduate students focuses on teaching the basics of polymer history, synthesis and characterization with connections to the core chemistry curriculum in a small class size environment and without a textbook. Furthermore, an extensive overview of the applications of polymeric materials gives students a connection to real life applications. The course includes polymer case studies, informational lessons on real world objects made of polymers, and demonstrations. Student …

A Chimeric Nucleobase - Phenylazo Derivative As An Intrinsic Nucleobase Quencher, Gyeongsu Park, Timothy Martin-Chan, Amer El Samm, Robert H.E. Hudson

Western Research Forum

Molecular beacons are important bioanalytical probes which are most often

constructed from a single-stranded oligonucleotide which has been labeled at

opposite termini with a fluorophore and a quencher. When the fluorophore and

quencher are in close proximity, no fluorescence is observed due to FRET

(Fluorescence Resonance Energy Transfer). DABCYL (4-dimethylaminoazobenzene-

4'-carboxylic acid) has been used as a quencher in the molecular beacon to absorbs

excitation energy from a fluorophore and to dissipate the energy as heat. However,

DABCYL is unable to form a base-pair and is conventionally placed as an overhanging

residue. This produces a derivative wherein the chromophore has …

Preparation, Modification, Characterization, And Biosensing Application Of Nanoporous Gold Using Electrochemical Techniques, Jay Bhattarai, Dharmendra Neupane, Bishal Nepal, Vasilii Mikhaylov, Alexei Demchenko, Keith Stine

Chemistry & Biochemistry Faculty Works

Nanoporous gold (np-Au), because of its high surface area-to-volume ratio, excellent conductivity, chemical inertness, physical stability, biocompatibility, easily tunable pores, and plasmonic properties, has attracted much interested in the field of nanotechnology. It has promising applications in the fields of catalysis, bio/chemical sensing, drug delivery, biomolecules separation and purification, fuel cell development, surface-chemistry-driven actuation, and supercapacitor design. Many chemical and electrochemical procedures are known for the preparation of np-Au. Recently, researchers are focusing on easier and controlled ways to tune the pores and ligaments size of np-Au for its use in different applications. Electrochemical methods have good control over fine-tuning …

Electron Injection From A Carboxylic Anchoring Dye To Tio2 Nanoparticles In Aprotic Solvents, Hui Fang, Yuhao Wu, Danielle L. Kuhn, Brendan G. Delacy, Yi Rao, Hai-Lung Dai

Chemistry and Biochemistry Faculty Publications

Injection of photoexcited electrons in the para-Ethyl Red dye to TiO₂ nanoparticles (Anatase, 40 nm diameter) is characterized by transient absorption on ultrafast time scales. This study focuses on understanding the effect of aprotic solvents on the injection rate. Transient absorption at 1900 cm⁻¹ is probed following a 400 nm pulse which excites the electronic transition of p-ER adsorbed on TiO₂ through its carboxylic group. Measurements conducted in three different solvents show that electron injection lifetimes are in the 250–300 fs range but display a trend in correlation with solvent polarity: the electron injection lifetime is the …

Analysis Of Metallic Components Of Gsr From Various Types Of Ammunition And Firearms Utilizing An Sem-Edx, Jenna A. Campbell

Graduate Student Research Symposium

Gunshot residue (GSR) is a chemical reaction that occurs when a firearm is discharged, which emits a cloud of gases from the barrel of the gun. It consists of both the burned and unburned propellant and primer components. These components are either organic or inorganic in nature, respectively. The organic components are located in the gunpowder part of the bullet, while the inorganic components are located in the primer part of the bullet. The primer consists of lead, barium, and antimony. These elements are considered heavy metals. Additionally, lead, barium, and antimony are the three key elements found in the …

Crystal Growth And Surface Modification Of Pyrite For Use As A Photovoltaic Material, Eric Rustad Young

Dissertations and Theses

Pyrite (FeS₂) has recently attracted significant interest as a photovoltaic material due to its promising optical properties, high photon to electron conversion yield, and low-cost raw materials. However, hopes have been tempered by recent discoveries that suggest the presence of hard to remove bulk sulfur defects. This research was focused on engineering and implementing the crystallization of pyrite from a sulfur rich solution to counteract the material's natural tendency to form bulk sulfur defects. Homoeptiaxial layers and single-crystal samples have been grown from tellurium sulfur melts with an Fe:S ratio of 1:4 using both natural and synthetic substrates. …

Molecular Dynamics Study Of Homo-Oligomeric Ion Channels: Structures Of The Surrounding Lipids And Dynamics Of Water Movement, Thuy Hien Nguyen, Catherine C. Moore, Preston B. Moore, Zhiwei Liu

College of Science & Mathematics Departmental Research

Molecular dynamics simulations were used to study the structural perturbations of lipids surrounding transmembrane ion channel forming helices/helical bundles and the movement of water within the pores of the ion-channels/bundles. Specifically, helical monomers to hexameric helical bundles embedded in palmitoyl-oleoyl-phosphatidyl-choline (POPC) lipid bilayer were studied. Two amphipathic α-helices with the sequence Ac-(LSLLLSL)3-NH2 (LS2), and Ac-(LSSLLSL)3-NH2 (LS3), which are known to form ion channels, were used. To investigate the surrounding lipid environment, we examined the hydrophobic mismatch, acyl chain order parameter profiles, lipid head-to-tail vector projection on the membrane surface, and the lipid headgroup vector projection. We find that the lipid …

Erratum: Author Correction: Identification Of Aspergillus Fumigatus Udp-Galactopyranose Mutase Inhibitors (Scientific Reports (2017) 7 1 (10836)), Julia S. Martin Del Campo, Meital Eckshtain-Levi, Nancy J. Vogelaar, Pablo Sobrado

Chemistry Faculty Research & Creative Works

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Investigation Of Temperature Response Of Photopolymer Material Used For Holographic Sensor, Muhammad Irfan, Tatsiana Mikulchyk, Suzanne Martin, Izabela Naydenova

Conference Papers

Recently, functionalised photopolymer has emerged as a versatile recording material in the field of optical holography due to its novel characteristics and potential use in the development of holographic based sensors, and optical elements. This work describes the temperature response of a newly developed photopolymer, containing of a monomer Nisopropylacrylamide (NIPA) which under photopolymerisation forms a temperature sensitive polymer - Poly(Nisopropylacrylamide) (PNIPA). The photonic sensor was developed by holographic recording of volume phase transmission gratings in a self-processing NIPA-based polymer with a 532 nm laser beam. A 633 nm probe beam was used to monitor real time diffraction efficiency (DE) …

Supported Perovskite-Type Oxides: Establishing A Foundation For Co2 Conversion Through Reverse Water-Gas Shift Chemical Looping, Bryan J. Hare

USF Tampa Graduate Theses and Dissertations

Perovskite-type oxides show irrefutable potential for feasible thermochemical solar-driven CO₂ conversion. These materials exhibit the exact characteristics required by the low temperature reverse water-gas shift chemical looping process. These properties include structural endurance and high oxygen redox capacity, which results in the formation of numerous oxygen vacancies, or active sites for CO₂ conversion. A major drawback is the decrease in oxygen self-diffusion with increasing perovskite particle size. In this study, the La_0.75Sr_0.25FeO₃ (LSF) perovskite oxide was combined with various supports including popular redox materials CeO₂ and ZrO₂ along with more abundant …

Synthesis Of Oxadiazoles And Examination Of Steric Effects In A Cyclodehydration Reaction, Norah Young

Undergraduate Honors Thesis Projects

The objective of this project is to develop a general substrate scope by testing various steric and electronic effects. This is pursued by developing triphenylphosphine dibromide (PPh3Br2) as an effective cyclodehydration reagent for use with a variety of hydrazides and sterically and electronically different benzoic acids. The two phases of the experiment include assessing yield through a cyclodehydration reaction and comparing that yield to the steric hindrance and molecular structure recorded in different databases. The cyclodehydration reaction uses ortho-substituted benzoic acid with store bought PPh3Br2, and compares those yields to the use of a two step-one pot reaction in place …

It’S Raining : Remotely Accessible Instruments In Nanotechnology To Promote Student Success, Jared M. Ashcroft, Atilla Ozgur Cakmak, Jillian Blatti, Esteban Bautista, Vanessa Wolf, Felix Monge, Dwaine Davis, M. Josefina Arellano-Jimenez, Raymond Tsui, Richard Hill, Anthony Klejna, James S. Smith, Gabe Glass, Timothy Suchomski, Kristine J. Schroeder, Robert K. Ehrmann

Current Issues in Emerging eLearning

Remotely Accessible Instruments in Nanotechnology (RAIN) is a community of educators that aims to bring advanced technologies into K-12 and college classrooms via remote access. RAIN's mission is to facilitate the study of nanoscale science by lowering barriers for instructors to deliver relevant educational activities for younger students interested in learning about nanotechnology across traditional STEM fields. Additionally, RAIN engages the next generation STEM workforce with a connection to experts, tools and institutions where cutting-edge research is being performed. This resource is particularly vital for underrepresented and minority students, especially those attending institutions that cannot provide on-site access to advanced …

Electrolyzer Design For Flexible Decoupled Water Splitting And Organic Upgrading With Electron Reservoirs, Wei Li, Nan Jiang, Bo Hu, Xuan Liu, Fuzhan Song, Guanqun Han, Taylor J. Jordan, Tanner B. Hanson, T. Leo Liu, Yujie Sun

Chemistry and Biochemistry Faculty Publications

The Bigger Picture

Electrocatalytic water splitting is a green approach to producing clean H₂ fuel, especially when it is driven by renewable energy sources. Conventional water electrolysis always produces H₂ and O₂ simultaneously under corrosive acidic or alkaline conditions with large voltage inputs, posing safety concerns of H₂/O₂ mixing. Therefore, it is desirable to develop a new electrolyzer design for decoupled water splitting in an eco-friendly neutral solution with small voltage inputs to enable separated H₂ and O₂ evolution. Herein, we report (ferrocenylmethyl)trimethylammonium chloride and Na₄[Fe(CN)₆] as proton-independent …

Non-Methane Organic Gas Emissions From Biomass Burning: Identification, Quantification, And Emission Factors From Ptr-Tof During The Firex 2016 Laboratory Experiment, Abigail R. Koss, Kanako Sekimoto, Jessica B. Gilman, Vanessa Selimovic, Matthew M. Coggon, Kyle J. Zarzana, Bin Yuan, Brian M. Lerner, Steven S. Brown, Jose L. Jimenez, Jordan Krechmer, James M. Roberts, Carsten Warneke, Robert J. Yokelson, Joost De Gouw

Chemistry and Biochemistry Faculty Publications

Volatile and intermediate-volatility non-methane organic gases (NMOGs) released from biomass burning were measured during laboratory-simulated wildfires by proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF). We identified NMOG contributors to more than 150 PTR ion masses using gas chromatography (GC) pre-separation with electron ionization, H3O+ chemical ionization, and NO+ chemical ionization, an extensive literature review, and time series correlation, providing higher certainty for ion identifications than has been previously available. Our interpretation of the PTR-ToF mass spectrum accounts for nearly 90ĝ€-% of NMOG mass detected by PTR-ToF across all fuel types. The relative contributions of different NMOGs to individual exact ion masses are …