DEPARTMENT of CHEMISTRY
2016 RESEARCH EXPERIENCES FOR UNDERGRADUATES FINAL SYMPOSIUM July 28, 2016 Buehler Hall 511 www.chem.utk.edu/reu
Symposium Schedule 1:00 ......................................................................................................... Alexia Thomas 1:15 ....................................................................................................... Selena Ledesma 1:30 ............................................................................................................... Claire Neice 1:45 ............................................................................................................. Kelsey Webb 2:00 .......................................................................................................................... Break 2:15 ......................................................................................... Joselyn Resto-Santana 2:30 ......................................................................................................... Desiree Moore 2:45 ......................................................................................................... Thomas Reyes 3:00 ................................................................................................ Jacob Kronenberg 3:15 ............................................................................................................................ Break 3:30 ................................................................................................ Adelaide Bradicich 3:45 ........................................................................................................... Bradley Terry 4:00 ................................................................................................ Gerard Van Trieste 4:15 ........................................................................................................... Michael Houle
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The University of Tennessee at Knoxville • Department of Chemistry
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Myo-Inositol Analogs for Labeled Investigation of Signaling Lipids Alexia Thomas1, Tanei Ricks2, and Dr. Michael Best2 1. Jackson State University 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract Signaling lipids play a vital role in many critical biological processes due to their active role in modulating protein functions. The specialized ability of signaling lipids such as, phosphatidic acid (PA), lyso-phosphatidic acid (LPA), and phosphatidylinositol polyphosphates (PIPns), results in key roles in the regulation of protein binding, trafficking, signaling, and the onset of diseases, such as cancer and diabetes. Unfortunately, valid characterization of lipid activity at the molecular level remains difficult; due to the complexity of their cellular environment. The development of synthetic lipid analogs provides a promising approach to the labeling of lipid products in live cells, enabling fluorescence imaging to detect the localization of these important biomolecules. Specifically, we synthesize various analogs of myo-inositol, a vital core unit of many PIPns. Through bioorthogonal reactions, specific biomolecules were designed, bearing a lipid precursor head group and a clickable tag for detection analysis, and synthesized while limiting disturbance of their biological activities. Chemically synthesized tagged analogs were introduced to live cells where the native biomachinery produced labeled lipid products. Labeled products were characterized for cellular incorporation through fluorescence imaging and mass spectrometry. A synthetic tagged analog approach will provide an advanced understanding of how these specific biomolecules play a role in biological events, such as upregulation of cell growth and tumorigenesis in cancer.
www.chem.utk.edu
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Synthesis and Characterization of the ZorO Protein Selena Ledesma1, Caleb Gibson2, Eric Tague2, and Dr. Shawn Campagna2 1. Berea College 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract Relatively little study has focused on small proteins less than 50 amino acids long, which are translated from small open reading frames. However, many small proteins have begun to gain attention and are being investigated for their biological functions. Z protein often repeated (ZorO), one of these small proteins, is 29 amino acids long and found in pathogenic Escherichia coli. This protein is toxic to the bacteria when overproduced, and this toxicity is repressed by the base pairing of an antitoxin with the ZorO-encoding mRNA, thus making a type 1 toxin-antitoxin pair. While the toxicity of ZorO has been observed, its full biological role is not yet known. However, it is hypothesized that the proteins ability to dimerize is related to its biological function. The aim of this project is to synthesize pure ZorO protein. The synthesis of the protein was carried out via solid phase peptide synthesis (SPPS), which involves the use of a solid support (resin), linkers, activating groups, and protecting groups. For this project an fluorenylmethyloxy-carbonyl (Fmoc) based approach was selected. The C-terminal residue was anchored onto an aminomethyl resin with a 4-(hydroxymethyl)phenoxyacetic acid (HMPA) linker. For the coupling reactions, 2-(1Hbenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU) was used as a coupling reagent in combination with N,N-diisopropylethylamine (DIPEA). As a result, the protein was successfully synthesized as confirmed by ultra-performance liquid chromatography—tandem mass spectrometry (UPLCMS/MS) using a Q Exactive mass spectrometer. The synthesized protein will be used for biological studies.
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The University of Tennessee at Knoxville • Department of Chemistry
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Microfluidic Paper Electrophoresis: Device Design and Operating Procedures to Reduce Joule Heating Claire Neice1, and Dr. Chris Baker2 1. Virginia Polytechnic Institute and State University 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract Mass Spectrometry (MS), which serves as our most specific detection method for analyzing biological samples, tends to be coupled with separations methods to mitigate ionization suppression. Paper electrophoresis (PE) uses volumes favorable to MS and is easily coupled to the detection method via paper-spray ionization, but joule heating and sample adsorption pose challenges to its application. We sought to reduce joule heating by encasing the channel in a glass device, cooling the device, varying the buffer, and using a thinner channel width. We performed these characterizations on a Fisher Scientific P8 filter paper channel. Each step to reduce joule heating expanded the linear Ohm’s Law region of the paper channel. The range of linearity for an open-air channel only reached 200 V. Using our PE device, we expanded that range to 500 V. When we integrated our cooling apparatus, the range of linearity lengthened to 700 V. Switching from our initial borate buffer to TRIS buffer extended the range to 800 V. Decreasing the width of our channel expanded the range of linearity to 1300 V. These extended linear ranges demonstrate that we successfully decreased joule heating and show that we can perform separations at higher voltages on our experimental setup. Future work includes characterizing various low adsorption filter papers, performing a separation on our device, and adapting it to achieve paper-spray ionization.
www.chem.utk.edu
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Surface-Enhanced Spatially Offset Raman Spectroscopy (SESORS) for Neuroscience Kelsey Webb1, Amber Moody2, and Dr. Bhavya Sharma2 1. The University of Virginia’s College at Wise 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract The ability to detect and quantify individual neurotransmitters in the brain is essential for a better understanding and treatment of life-threatening neurological diseases. Various commonly used cerebral imaging techniques are effective for disease detection, yet most lack the ability to determine the concentration of neurotransmitters present in the brain. Current methods for identifying and measuring the concentration of neurotransmitters are invasive and involve drilling into the skull. This study explores a safe, noninvasive method for detecting and quantifying neurotransmitters by combining two powerful Raman spectroscopy techniques, surface-enhanced Raman Spectroscopy (SERS) and spatially offset Raman spectroscopy (SORS). SERS provides a significantly enhanced Raman signal by adsorbing the analyte to noble metal nanoparticles. SORS allows for Raman measurements to be made through a diffusely scattering material by collecting the scattered light at a particular offset from the illumination point. We have acquired SERS measurements of benzenethiol and five neurotransmitters (dopamine, epinephrine, GABA, melatonin, and serotonin) adsorbed to gold nanoparticles. We performed surface-enhanced SORS (SESORS) measurements through a cat skull on these neurotransmitters in an agarose gel (brain tissue mimic). We have reported SESORS measurements of benzenethiol, epinephrine, dopamine, and melatonin, which successfully demonstrate the ability to use this technique.
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The University of Tennessee at Knoxville • Department of Chemistry
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Imaging β-carotene in Lipid Bilayers of Giant Unilamellar Vesicles by Ultrafast Transient Absorption Microscopy Using Photonic Crystal Fiber Joselyn Resto-Santana1, Kevin Higgins2, and Dr. Tessa Calhoun2 1. Department of Chemistry, University of Puerto Rico, Mayagüez 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract Synthetic biological model membranes: Giant Unilamellar Vesicles (GUVs) were synthesized by a sonication method, yielding sizes of about 5 µm to 48 µm. Two dyes, Nile red and DASPI, were added in the GUVs membranes, and in order to determine whether or not those dyes were incorporated in the lipid bilayers of a GUV, a fluorescent microscope was used. Fluorescent images proved that both dyes were successfully incorporated in GUV membranes. That demonstrated that it is possible to incorporate small molecules in a GUV lipid bilayer and subsequently analyze them using transient absorption microscopy (TAM). TAM will be used for studying and imaging a non-fluorescent molecule, β-carotene, by probing its electronic excited states. Two different photonic crystal fibers (PCF), Femtowhite CARS and NL-1.4-775 were tested, in order to incorporate them into the TAM optical set up to generate a supercontinuum spectrum. Using a Ti:Sapphire oscillator laser at 800 nm, 68 fs and 80 MHz, the Femtowhite CARS PCF exhibited white light supercontinuum output. As the next approach on this study, the bare PCF will be implemented into the current TAM instrument, and used to study the electronic structure of biological systems by imaging membrane- β-carotene interaction in GUVs, and further, in living cells like bacteria.
www.chem.utk.edu
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Towards the Synthesis of a Novel Dirhodium(II) Paddlewheel Catalyst for Cyclopropanation Reactions Desiree Moore1, Derek Cressy2, and Dr. Ampofo Darko2 1. Roanoke College 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract Dirhodium (II) paddlewheel catalysts have proven to be beneficial for several different transformations such as cyclopropanation, cyclopropenation and cycloaddition reactions. Under certain conditions, these catalyzed reactions often provide products in enantiomeric excess. Each enantiomer potentially has different properties in biological and chemical applications. Enantiopure products are very important in several areas including pharmaceuticals, agrochemicals and biological applications. Previous studies on dirhodium paddlewheel complexes focus on ligand exchange of the dirhodium as a strategy to provide stereoselectivity in a variety of different organic reactions. Recently, axial coordination has become more relevant and shows great potential for enhancing stereoselectivity in cyclopropanation reactions. To expand the scope of selectivity through axial coordination, the current study explores the synthesis of a heteroleptic dirhodium paddlewheel complex with a sulfide axial ligand derived from thiophenol. The complex will be used to catalyze the cyclopropanation reaction using ethyldiazoacetate and styrene as a standard test reaction.
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The University of Tennessee at Knoxville • Department of Chemistry
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Increasing Interfacial Strength in Fused Deposition Modeling of Polymers Thomas Reyes1, Neiko Levenhagen2, Madeline Stark2, Connor Perryman2, and Dr. Mark Dadmun2 1. University of Alabama, Huntsville 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract Fused deposition modeling (FDM) uses an extruder to heat a filament to print an object layer by layer. Oriented fibers have strong tensile strength but are weak when pulled at a right angle of the orientation. Currently 3D printing using FDM has weak interfacial adhesion due to the lack of diffusion across layers. Mixing different molecular weight polymers and crosslinking between the layers using 4,4’-diaminodiphenylmethane (DADPM) one can increase the interfacial adhesion. A filament made from two different molecular weight polymers was used to 3D print a cube. Samples are cut from the cube to test both the interfacial adhesion and tensile strength. DADPM was added at varying concentrations and times between T peel layers to induce crosslinking. Both methods have been recorded to have an increase in interfacial adhesion. By increasing the interfacial adhesion stronger objects can be made using 3D printing.
www.chem.utk.edu
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Polymeric Ionic Liquids for Use in Mechanical Lubrication Jacob Kronenberg1, Dr. Wenxin Fu2, and Dr. Bin Zhao2 1. Tufts University 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract Improving lubricant performance can significantly increase energy efficiency and decrease costs ranging from industrial processing to the automotive sector. When developing lubricants, it is important to create substances that decrease friction between surfaces, reduces wear, and functions over a broad range of temperatures. Hydrophobic ionic liquids are a promising type of lubricant additive, reducing friction and wear primarily through metal-anion interactions and the formation of a protective film on the metal surface. We report a synthetic route and progress toward a new, phosphonate-bearing monomer, 11-(ethoxy(hydroxyl)phosphoryl)undecyl methacrylate, for the synthesis of polymeric ionic liquid additives, combining the anti-wear and friction-reducing effects ascribed to ionic liquids with the viscosity index-improving properties of poly(alkyl methacrylate) lubricant additives. This hydrophobic monomer is synthesized by functionalizing bromoundecanol with methacryloyl chloride and triethyl phosphite. The final ionic liquid monomer is made more oleophilic through ion exchange with trihexyl(tetradecyl)phosphonium chloride. NMR and mass spectra for compounds are reported. Once synthesized, the tribological properties of the ionic liquid monomer and its polymer and its effect on viscosity will be studied. We believe this new polymer will allow for superior lubricant performance, increasing fuel efficiency and decreasing the need to replace mechanical parts.
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The University of Tennessee at Knoxville • Department of Chemistry
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The Catalytic Properties of the Phases of Aluminum Oxide Adelaide Bradicich1, Daniele Paradiso2, Nicholas Strange2, and Dr. John Larese2 1. Texas A&M University, Commerce 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract Ethylene is an often-used chemical in the plastics industry that can be obtained efficiently by dehydrating ethanol. To carry out this reaction, aluminum oxide (Al2O3) is used as a catalytic support. Aluminum oxide (alumina)transitions through different metastable crystalline phases during the conversion from boehmite to corundum, each of which has unique surface properties arising from the differences in bulk crystal structure. Consequently, three different phases were tested for optimal catalytic performance, namely γ- Al2O3, θ- Al2O3, and α- Al2O3 (corundum). These phases of alumina were prepared through the calcination of the mineral boehmite (AlOOH). Initial characterization will include x-ray diffraction, NMR, and volumetric adsorption isotherms. Isothermal techniques will be used to adsorb ethanol to the sample.Temperature programmed desorption (TPD) using a modified gas chromatogram and thermal conductivity detector (GC-TCD) with controlled vapor-dosing capabilities will be used to desorb the reaction’s products from the surface and test for conversion at a variety of temperatures(~25-300°C). The TPD results will be analyzed to determine the yield of ethylene, and a comparison will be made of the yields using different phases of Al2O3 as catalysts. These results will be coupled with in-situ inelastic neutron scattering measurements to provide an in depth understanding of the hydrogenation reaction and the catalytic efficiencies of these transition-phase aluminas.
www.chem.utk.edu
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Chromium-Tetracarbene Complexes for Aziridination Catalysis Bradley Terry1, Dr. Jesse Kern2, and Dr. Sharani Roy2 1. Oakland University 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract Transition metal-tetracarbene catalysts have recently attracted interest due to their efficacy in successfully catalyzing aziridination reactions between organic azides and alkenes. Aziridines are the nitrogen analog of epoxides that can readily undergo ring-opening reactions to form a bevy of useful compounds for medical and industrial applications. We aim to understand the underlying mechanism behind this catalytic process using density functional theory (DFT), and suggest improvements for choice of azide that will enhance reaction speed and yield. The chosen class of catalyst contains 2 chromium-macrocyclic tetracarbene complexes. Results of this study indicate that this mechanism contains two key intermediates – a chromium-imide species and a chromium-tetrazene species. Notably, the TPSSh functional predicts that the tetrazene intermediate is an extremely stable intermediate, which heavily impedes the optimal catalytic cycle. Further investigation will be into reducing the stability of the tetrazene intermediate. By encouraging the reaction to proceed down the desired pathway, the aziridine product yield may be augmented.
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The University of Tennessee at Knoxville • Department of Chemistry
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Putting the Syn in Synthesis: 2,7-Ditriazole Anthracene Linker for MONTS Gerard Van Trieste1, Kristina Vailonis2, and Dr. David Jenkins2 1. Shippensburg University 2. Department of Chemistry, University of Tennessee, Knoxville
Abstract Metal-organic nanotubes (MONTs) are the one dimensional counterpart to the well-studied and understood three dimensional metal-organic frameworks (MOFs). Necessary investigation into MONT growth and aggregation patterns should yield insight into the fundamental properties of MONTs. Thus, the differences in properties due to having a single dimension will be explored. This will be facilitated through a dimethylanthracene moiety bound to triazoles to serve as an optically active ligand. The optical activity is advantageous due to the myriad of fluorescent and absorbent spectroscopic methods with allow the growth, aggregation patterns, the pore size to be monitored in situ. This has advantages over previous spectroscopic methods due to the ability for time dependent measurements. Upon completion of the ligand synthesis, combinatorial MONT reactions will be performed. These optically active MONTs will provide supplementary information to previous studies, and facilitate new insight into the time dependency of MONT growth.
www.chem.utk.edu
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Views from the Outside Michael Houle Department of English, University of Tennessee, Knoxville
Abstract Each of this year’s REU students and Michael’s experience with them will be highlighted in this talk. One adjective will be used to describe each student and stories about them will be shared.
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The University of Tennessee at Knoxville • Department of Chemistry
Notes
www.chem.utk.edu
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Department of Chemistry 552 Buehler Hall 1420 Circle Dr. University of Tennessee Knoxville, TN 37996-1600
Phone: 865-974-3141 Fax: 865-974-9332 Email: chemistry@utk.edu