Loading…
Spring Symposium on UR and Community Engagement has ended

Sign up or log in to bookmark your favorites and sync them to your phone or calendar.

Chemistry [clear filter]
Tuesday, April 24
 

8:00am PDT

Decomposition Behaviour Of HCFC-123 And Of Chlorocylclopropane Adducts
The objective is to prepare chemically activated CF3CHCl2 from the combination of CF3 and CHCl2 radicals. CHCl2I was synthesized to use photocatalysis facilitated by Hg2I2 for generating the CHCl2 radical. The unimolecular decomposition reactions were qualified by identifying the products, and the rates of reaction will be quantified based on the ratio of decomposed products using a 2010 Shimadzu gas chromatograph mass spectrometer, GC-MS QP2010. The intent of this study is to expand data on the degradation reactions that hydrochlorofluorocarbons (HCFCs) will undergo, as they are a commercially important class of greenhouse gases, which are in the process of being re-engineered to be more environmentally friendly. Understanding these reactions is key to the efficient recycling of HCFCs. To date, CF3CHCl2 (also called HCFC-123) has been formed by the aforementioned photolysis process, and identified. We have also confirmed that the :CClCF3 carbene, formed by the 1,1-HCl elimination reaction, can be trapped using either cis- or trans-2-butene. We have not been able to detect formation of CF2=CHCl from a 1,1-HF elimination reaction. Thus, it appears that the 1,1-HCl elimination pathway is overwhelmingly dominant compared to the 1,2-HF elimination pathway, but quantitative data derived from the rates of these reactions and computational work to predict threshold energies for each pathway is needed. This semester's work has been to investigate a side reaction resulting from trapping the :CClCF3 carbene with either cis- or trans-2-butene. The resultant three-membered ring is an unstudied novel system, and appears too complex to analyze directly, but comparison to similar known systems yields a theoretical interpretation.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 8:00am - 8:20am PDT
202 Zeis Hall

8:00am PDT

Synthesis And Bacterial Assessment Of Modifications To The Core Of Depsidone
Depsidones are a class of natural products that exhibit antibacterial activity (MIC = 0.0825-8 ppm). In order to increase the antibiotic potency of the depsidone family of natural products, modifications in size and connectivity are being explored. Although a synthesis scheme for the core 6,7,6-fused tricyclic structure of depsidone exists, the yields of the final product are low. In an effort to increase the yields, a new synthetic scheme has been derived which involves Chan-Lam copper catalyzed coupling of boronic acid and a diol substituted benzene rings followed by deprotection and esterification steps to close the central ring. Following this same synthesis scheme, a series of analogs has been synthesized investigating the role that steric hindrance, electronegativity, and hydrogen bonding has on the activity of the compound. These changes will provide insight into the affect the electronic interactions have on antibiotic activity and potentially indicate the mechanism of action of the compound. All analogs synthesized will be evaluated in an antibacterial assay against Gram-positive and Gram-negative bacteria in order to build a structure activity relationship profile for the depsidones.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 8:00am - 8:20am PDT
123 Zeis Hall

8:20am PDT

Development Of A Reconstitution Protocol For ATP Synthase With Various Lipids
H+ transporting ATP synthase is a remarkable molecular machine that catalyzes the synthesis of ATP by use of two coupled motors, F0 and F1. The use of H+ electrochemical gradient drives rotation of the c ring which couples with the F1 domain to induce conformational changes that catalyze the formation of ATP form ADP and inorganic phosphate. The F0 section of ATP synthase is primarily embedded in the membrane, so it is possible that lipid contacts and composition could play a role in proton translocation and function. Cardiolipin, a phospholipid that comprises a significant portion of the inner mitochondrial membrane, residues have been seen using electron cryo-microscopy. These lipid effects could be essential for normal function. A protocol for reconstitution of ATP synthase will be developed, with emphasis on different techniques for detergent removal and liposome recollection.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 8:20am - 8:40am PDT
123 Zeis Hall

8:20am PDT

Photodegradation Of Trichloroethylene In The Presence Of Titanium Dioxide Nanoparticles
With the increased presence of common industrial waste solvents in the nation’s water supply, it has become imperative to employ affordable and commercially-practical water purification methods. One such method involves the use of Titanium Dioxide (TiO2) nanoparticles (NPs), which offer new options for water filtration due to their nanoscale size and corresponding large overall surface area. TiO2 is widely available, and non-toxic, making it an attractive option for removal of organic contaminants from water. These NPs exhibit photocatalytic characteristics in the presence of the organic contaminants and ultraviolet light, while remaining inert in the absence of UV light. In this study, the effectiveness of TiO2 NPs as a base material for the photodegradation of the common industrial contaminant trichloroethylene (TCE) is explored. Preliminary data suggest that TiO2 is an effective medium for the removal of TCE from aqueous solutions.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 8:20am - 8:40am PDT
202 Zeis Hall

8:40am PDT

Computational Investigation Of Alcohol Dehydrogenation On An Extended Stepped Rhodium Catalyst Surface Using Density Functional Theory
Since the industrial revolution, an increased demand on fossil fuels as the predominant source of global energy have brought upon many harmful consequences, such as environmental pollution, climate change, and depletion of Earth’s non-renewable natural resources. Proton-Exchange Membrane (PEM) fuel cells are being researched as an alternative to generate electricity and hydrogen gas is used as fuel. However, hydrogen gas is not abundant in nature and has to be derived from hydrogen containing molecules like fossil-fuel hydrocarbons. Complex alcohols and carbohydrates are a sustainable alternative. These compounds contain long chains of hydrogen, oxygen, and carbon atoms. Transition metal catalysts, such as rhodium (Rh), can be used to break the C-H, O-H, and C-C bonds of these molecules to release hydrogen gas as byproduct. But a better understanding of the catalytic reaction mechanisms is needed to fully utilize complex alcohols for hydrogen generation. For this research, the computational method periodic density functional theory (DFT) is used to investigate C-H and O-H bond cleavage over a Rh metal catalyst. There are different types of catalytic metal lattice structures, such as planar, stepped, and kink surfaces. Recent studies have shown that the stepped and kink surfaces are more reactive and allow compounds to bind much stronger to the metal surface. By using periodic DFT, this project will investigate the reaction mechanisms for breaking C-H and O-H bonds of alcohols using an extended stepped Rh(211) catalyst surface. The results will be compared to previous research done on the O-H and C-H bond cleavage of the same alcohols on a planar Rh(111) surface to further understand the catalytic properties of the stepped rhodium surface.


Tuesday April 24, 2018 8:40am - 9:00am PDT
202 Zeis Hall

8:40am PDT

Role Of The Iridium-Nitrogen Interaction In Catalytic Transfer Hydrogenation
Transfer hydrogenation is the process of adding hydrogen to a molecule from a non H2 source. This process is more efficient than direct hydrogenation because the non H2 sources are more readily available and inexpensive compared to H2 sources. Many different metal catalyst attached to ligands have been used to determine which is best for the reaction as well as the most efficient way to get to the end product. We will use an iridium catalyst along with a non H2 source to determine which hydrogen from the source goes where on the molecule. In addition to finding out if this process is going to be stepwise or concerted.

Moderators
Speakers

Tuesday April 24, 2018 8:40am - 9:00am PDT
123 Zeis Hall

9:10am PDT

Characterization Of Unimolecular Elimination Reactions For CD3CD2CHFCl
Hydrochlorofluorocarbons (HCFCs) are greenhouse gases and can deplete the ozone layer. To stop further adverse effects, the Montreal Protocol requires HCFCs to be collected and destroyed by 2020 for developed countries and 2030 for developing countries. We studied the decomposition reactions of CD3CD2CHFCl as a model system to emulate HCFCs currently in use to better understand how they would react when subjected to high temperature in a destruction chamber. The unimolecular reactions of energized CD3CD2CHFCl molecule are 1,1-HCl, 1,1-HF, 1,2-DCl and 1,2-DF elimination with a ratio of 0.16: 0.004: 0.82: 0.013. All elimination pathways form cis- and trans-alkenes and the ratio varied from 1 to 3.5. The data collected shows that 1,1-HX (X=Cl, F) elimination reaction, forming a carbene, can became the dominant degradation pathway at high temperatures. After all results have been collected, they are calibrated to account for the fact that different molecules fragment differently. Calibrations using the stabilized product were done via proxy because some pure samples could not be acquired. Calibration factors are multiplied to the data and ranged from 1.71 to 8.38. By studying these degradation pathways, we can better understand how to destroy them or convert them into feedstock for other industries after they are all banned.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 9:10am - 9:30am PDT
202 Zeis Hall

9:10am PDT

Synthesis and Antibiotic Assessment of Pestalone Derived Aryl and C9 Analogs
Pestalone (1) is a natural product first isolated by W. Fenical et al. in 2001 from a cofermentation of a marine fungus and antibiotic-resistant marine bacterium. It was reported to have highly potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MIC = 37 ng/mL) and vancomycin-resistant Enterococcus faecium bacteria (MIC = 78 ng/mL). Consequently, this made pestalone a promising, new antibiotic compound. Due to its challenging chemical structure, total synthesis of 1 has only been achieved by Iijima et al. and Slavov et al. Unfortunately, the latter group reports multiple difficulties during and after total synthesis which include the facile intramolecular cyclization between the C9 aldehyde and bridging ketone forming a lactone, rendering it inactive and discrepancies in the degree of antibacterial activity. In turn, we aim to synthesize C9 pestalone analogs incapable of undergoing the inactivating intramolecular cyclization by replacing the aldehyde with a range of electronic and steric functional groups. To date, eleven analogs were synthesized using a two-step synthesis involving first a Grignard addition of bromobenzene to a substituted phthalic anhydride (30-99% yield), and then modifying the produced carboxylic acid through esterification (47-76% yield) or amidation (7-50% yield). These analogs were then subjected to a broth microdilution minimum inhibitory concentration assay against Staphylococcus aureus, and it was found that only the analogs with the carboxylic acid showed activity. Continuing efforts are being made to access more analogs by synthesizing other substituted phthalic anhydrides.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 9:10am - 9:30am PDT
123 Zeis Hall

9:30am PDT

Computational Studies Of Oxidation And Reduction Of Copper Sulfonamides
Strongly chelating ligands such as sulfonamides are important in separation of metals, particularly in isolating trace elements. Further understanding of the nature of sulfonamide bonding could lead to a strong extraction agent for specific metals found in natural mineral deposits. It was determined experimentally that copper(II) coordinated to two sulfonamide ligands, Cu(sulf)2, had unusual geometrtic and potentiometric properties, being particularly stable with respect to multiple oxidations and reductions. Starting from the single-crystal X-ray generated geometry of Cu(sulf)2, a series of oxidized and reduced forms are studied using Density Functional Theory (DFT) and the Quantum Theory of Atoms In Molecules (ATAIM), in order to determine likely oxidation and reduction sites, and the nature of bonding of the ligand.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 9:30am - 9:50am PDT
123 Zeis Hall

9:30am PDT

Dihydropyrrole Synthesis From Novel Chalcones Via 6π Electrocyclizations
Numerous 6π conjugated systems were observed during an electrocyclization-condensation reaction in order to understand the way freely resonating electrons behave in π-orbitals in the presence of withdrawing and donating substituents. We predict that when the 6π carbanion system contains with a withdrawing or deactivating residue, the density of the π-electrons will be delocalized, causing the π-electrons to be more organized and stabilizing the system. Under the notion that electrocyclic systems are thermodynamic, the stabilization of the carbanion system will decrease the reaction entropy, as well as hindering product formation, thus resulting in a decrease in yield under a specific time frame. In turn, We predict that donating or activating residues will contribute to a less stable, more electron dense and more entropic intermediate and these cause product formation to occur in relatively higher yields than the former case described. The electrocyclic-condensation of glycine-ethyl ester hydrochloride and chalcone derivatives with varying electronic substituents is the reaction of interest. In the reaction, the chalcone and glycine- ethyl ester will condense to form a secondary imine intermediate. In the same pot, this intermediate will undergo an electrocyclization in order to form a dihydro-pyrrole. Several novel alpha-substituted chalcones were synthesized in good to excellent yield using a variety of methods, some novel. It was found that the dihydropyrrole formed was dictated by the alpha-substituent.General alpha hydrogen chalcones formed C-N pi bonded dihydropyrroles, whereas other alpha-substituted chalcones generated N-H dihydropyrroles other dihydropyrroles are being developed and the results will be reported.


Tuesday April 24, 2018 9:30am - 9:50am PDT
202 Zeis Hall

9:50am PDT

Mobile Low Resource Qualitative And Quantitative Laboratory Experimental Methods
There is a need for mobile-styled, low resource laboratory experimental methods, which do not require the use of expensive chemicals, volumetric glassware, and precise instrumentation, as well as running water and constant electricity. The purpose of this project is to create mobile styled, low resource, qualitative and quantitative laboratory experimental methods. The goal of the project is to apply these experimental methods in rural institutions, specifically in Ghana. A Wikipedia article related to Ethnochemistry is in progress.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 9:50am - 10:10am PDT
202 Zeis Hall

10:20am PDT

Unimolecular Decomposition of CD3CD2CHFBr
Halogenated hydrocarbons are important due to their ability to destroy ozone and act as greenhouse gases. In order to investigate the degradation reaction pathways for halogenated compounds, a model molecule, CD3CD2CHFBr, was prepared using the chemical activation technique. The activated CD3CD2CHFBr was prepared by combination of CD3CD2 and CHFBr radicals prepared by photosensitizing CD3CD2I and CHFBr2, respectively using Hg(3P0). The unimolecular decomposition pathways for CD3CD2CHFBr are still being analyzed. However, it was found that the E/Z ratio for the products of the decomposition changes with pressure. This may be due to an E/Z isomer shift caused by secondary mercury photolysis. It was also found that the 1,2-DBr elimination reaction leads to the prevalent product formed at all pressures analyzed.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 10:20am - 10:40am PDT
202 Zeis Hall

10:40am PDT

In-Vitro And In-Silico Synthesis Of Anticancer Compounds To Halt Rapid Cell Division And Cleave DNA
Combretastatin A-4 is a naturally occurring compound isolated from the South African bushwillow Combretum caffrum. A variety of its analogs, such as 3,5-diaryl-4-iodopyrrole-2-carboxylate derivatives, have demonstrated anti-mitotic, anticancer, and antibiotic properties. The formation of these analogs serve as useful intermediates to synthesize more complex heterocyclic systems in addition to being the core structure of all lamellarins. Different methods consist of a 3-step one-pot procedure including a halogenation, and others contain a purification step prior to the halogenation. Both methods have acquired decently high yields (53% - 88%) with the one-pot reaction on the higher end. Not only does the one-pot method seem to be more efficient, yet it is faster and contains fewer individual steps. Furthermore, these analogs are to be tested both in-vivo and in-silico.


Tuesday April 24, 2018 10:40am - 11:00am PDT
202 Zeis Hall

10:40am PDT

Optimization And Characterization Of Antibiotic Compounds Produced By Bacteria
Increasing bacterial resistance to current antibiotic treatments poses a huge threat to the health of the human population. Over the past 20 years, there has been a significant decline in the production of new antibiotics, despite the rapid emergence of drug resistant pathogens. The isolation and extraction of structurally unique antibiotics from bacteria remains largely uninvestigated by current researchers. Natural products, however, are an abundant source of structurally diverse compounds with antibacterial activity that can be used to develop new and potent antibiotics. This research investigates techniques for determining optimal growth media and optimal time of antibiotic production for each bacteria sample from a library of bacteria species, as well as the extraction of antibiotic active compounds from bacteria.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 10:40am - 11:00am PDT
123 Zeis Hall

11:00am PDT

Spectroscopic Study of mechanical movement in the Fo motor of E. coli ATP synthase
F1Fo ATP synthase is present in all life and is responsible for the production of almost all adenosine triphosphate (ATP), which is one of the most prolific energy molecules that are synthesized during metabolism. Fo converts electrochemical potential into mechanical rotation, which drives conformational changes in F1 that facilitate the synthesis of ATP. The mechanism of rotation of the subunit c ring is not known, but there are currently two hypotheses. This study will look for evidence of the ratcheting mechanism of rotation, which states that the helices of subunits a and c act like mechanical gears during rotation. This mechanism would require the α-helices of subunit a that lie on the a-c interface to move during rotation. Site directed mutagenesis was used to mutate aV71C, which is located on a loop. This mutant ATP synthase was purified and then chemically modified with a spin label, which can be observed using electron paramagnetic resonance (EPR) spectroscopy. The EPR signal is sensitive to the protein environment and will provide data on the mobility of the residue to which the spin label is attached. This particular mutant appeared to be immobile in the data collected. The quality of the data will be improved by using different purification methods and comparing their efficiency. Protein purification will be optimized using varying imidazole concentrations. A new ATPase assay will be developed.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 11:00am - 11:20am PDT
123 Zeis Hall

11:00am PDT

The Synthesis And Characterization Of The Functionalized Metal-Ligand Complex, [Co(4-brbpy)3]3+
Cobalt complexes formed from 2,2’-bipyridine (bpy) have been used to study electron transfer mechanisms, to facilitate redox reactions in solar cells, and to catalyze the reduction of alkynes. Investigation into solar cells for renewable alternative energy is of particular significance in the modern economic climate. However, there is comparatively less research into the preparation and use of functionalized cobalt-bpy complexes, notably those that could serve as reactants for additional chemical synthesis. In this research, a scheme for the synthesis and characterization of the as-yet unreported functionalized complex [Co(4-brbpy)3]3+ (4-brbpy = 4-bromo-2,2’-bipyridine) is proposed. The synthesis of this complex resembles that previously published for the related complex [Co(4-fbpy)3]3+ (4-fbpy = 4-fluoro-2,2’-bipyridine) with modifications taken from other similar syntheses. Characterization of the synthesized product is carried out via nuclear magnetic resonance (NMR), infrared (IR), and ultraviolet/visible (UV/vis) spectroscopies. Analysis of NMR spectra and accompanying COSY spectra suggest the precipitated solid product is the target [Co(4-brbpy)3]3+ complex. Spectroscopic measurements of purified [Co(4-brbpy)3]3+ is compared to those of the unfunctionalized complex [Co(bpy)3]3+ to understand how functionalization of the bpy ligand changes the properties of these complexes.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 11:00am - 11:20am PDT
202 Zeis Hall

11:20am PDT

Development of a liquid chromatography tandem mass spectrometry method for the detection and quantification of eleven common over-the-counter medications in human urine
Ibuprofen, loratadine, naproxen, and several other common over-the-counter medications are known inhibitors of glucuronosyl transferase, which are responsible for the metabolism and excretion of phthalates, ubiquitous industrial chemicals and environmental pollutants. Existing studies on phthalate diesters and their monoester metabolite concentrations in humans suggest individual metabolism of phthalates varies both between and within individuals, but the mechanism of this inter- and intra-individual variation remains unknown. Glucuronosyl transferase inhibition by over-the-counter medications may affect individual phthalate metabolism, and therefore may explain patterns in inter- and intra-individual metabolic variation. In the following study, novel liquid chromatography tandem mass spectrometry and solid phase extraction methods were developed to quantify over-the-counter medication levels in human urine of known phthalate monoester levels to assess their role in the inhibition of phthalate metabolism.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 11:20am - 11:40am PDT
202 Zeis Hall

11:20am PDT

Cloning Vomeronasal Type-2 Receptors For Expression And Analysis In A Cell Culture Model System
The vomeronasal organ (VNO) is an olfactory sense organ in the nose of mice that detects pheromone signals through ligand binding to G-protein coupled receptors. There are three families of VNO receptors, V1R, V2R, and FPR. V2Rs in mice primarily serve to bind large molecules like the major urinary proteins (MUPs), proteins secreted in urine that trigger contextual behaviors in the recipient. Through combinatorial coding, multiple combinations of MUPs can activate multiple V2Rs in different ways, leading to complex signals based on a small library of ligands. However, VNO receptors are orphaned, it is not known which MUP ligand binds with which VNO receptor. This research set out to deorphanize V2Rs and pair them with their cognate ligands to create a library of receptor-ligand pairings. Receptor deorphanization will involve cloning V2Rs into mammalian cells, then analyzing them using patch clamp to measure membrane voltage changes when exposed to MUP ligands. Sequences coding for V2Rs were amplified through PCR, visualized on a gel, relevant bands were extracted and purified, then TOPO cloned into bacterial plasmids and transformed into JM109 E. coli cells for mass growth. Plasmids from E. coli were restriction digested to verify insert sequence length, then ligated into mammalian pEGFP vectors for eventual transfection into eukaryotic cells. To date, receptors have been cloned, visualized, extracted, purified, and transformed for V2Rs 34, 60, 92, 121, 122, 81, and 83. One sample (122-1) indicated a full length sequence, and has been ligated and sent for sequencing. If the results indicate a full length sequence inside the mammalian vector, the plasmid will be transfected for surface expression. This experiment is an important first step to being able to better understand and map the exact neural pathways activated by an environmental chemical stimulus, and how it produces a response in the host.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 11:20am - 11:40am PDT
123 Zeis Hall

2:00pm PDT

Synthesis And Antibacterial Evaluation Of Core α-Pyrone Pseudopyronine A Analogs
With antibiotic resistance becoming an increasing problem in society, it is vital for chemists to search for novel antibacterial agents to combat this growing issue. α-Pyrones have been a known class of antibiotic natural products since 1983 that have been studied previously, and have been shown to be viable candidates for new research into other natural product α-Pyrones, including pseudopyronine A. α-Pyrone analogs of Pseudopyronine A, a natural product isolated from Pseudomonas species of bacteria, are being synthesized and evaluated for improved antibacterial activity against both Gram-positive and Gram-negative bacteria such as Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. Synthetic analogs are accessed through either the commercially available acyl chlorides or β-ketoesters, which will produce the α-pyrone in 5 or 3 steps respectively. The α-pyrones will then be further derivatized through several processes including thiol substitution, methylation, alkylation, amidation, or halogenation reactions. All derivatives will then be evaluated for antibacterial activity in a growth inhibition assay against a panel of both Gram-positive and -negative bacteria.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 2:00pm - 2:20pm PDT
123 Zeis Hall

2:00pm PDT

Unimolecular decomposition of CF3CHClCCl2 radicals chemically activated by the reaction of TCE and CF3 radicals.
Unimolecular decomposition of CF3CHClCCl2 radicals chemically activated by the reaction of TCE and CF3 radicals.

Pagnareach Tin
Dr. Bert Holmes
The Department of Chemistry at University of North Carolina Asheville

Abstract
Trichloroethylene (CHCl=CCl2) or TCE was widely used in the chemical industry due to its versatility and properties. The most common use for TCE is as a degreaser agent. Factories that produce products such as hearing aids used TCE to degrease metal components that were used in the production of hearing aids. Ever since TCE was banned by the Environmental Protection Agency (EPA) due to its carcinogenic properties, tons of TCE in used remained in the environment. A reaction between TCE and CF3 radicals was studied in order to determine possible pathways that TCE can react to form various products. Photolysis of CF3I was the source of CF3 radicals that subsequently added to the CHCl end of TCE producing chemically activated CF3CHClCCl2 radicals in the gas phase. The addition of CF3 radicals to the CCl2 end of TCE would produce CF3CCl2CHCl radicals, but quantum chemical calculations using Gaussian verified that this reaction was not important, in agreement with experimental findings. The chemically activated CF3CHClCCl2 radical decomposed by loss of atomic Cl to form CF3CH=CCl2 or was stabilized by collision with reactant molecules. The stabilized CF3CHClCCl2 radical combined with CF3 radicals yielding CF3CHClCCl2CF3. The atomic Cl added to TCE forming the CHCl2CCl2 radical that subsequently combined with CF3 radicals producing CHCl2CCl2CF3. Gas chromatography and mass spectra analysis were used to determine products that were formed in the reaction vessel. Three main products that formed were positively determined to be CF3CHClCCl2CF3, CF3CH=CCl2, and CF3CCl2CHCl2. Future studies include determining reaction pathway and characterizing final products of the reaction between CFCl=CFCl and CF3 radicals as well as trans-CHCl=CClCF3 and CF3 radicals.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 2:00pm - 2:20pm PDT
202 Zeis Hall

2:20pm PDT

Structural Dynamics In The FO Motor Of ATP Synthase Revealed By Site-Directed Spin-Labeling And CW-EPR
F1FO ATP synthase is present in all life and is responsible for the production of almost all adenosine triphosphate (ATP), the ubiquitous energy currency synthesized during cellular metabolism. The FO motor converts electrochemical potential into mechanical rotation, which drives conformational changes in the F1 facilitating the synthesis of ATP. The mechanism of rotation of the FO rotor (subunit c) ring is unclear, but there is some evidence that the stator (subunit a) is conformationally dynamic. This study looked for further evidence of a ratcheting mechanism of rotation, which would require the α- helices of subunit a that lie on the a-c interface to move during rotation. Site directed mutagenesis was used to introduce cysteine into several positions on subunit a. The mutant ATP synthase was purified, chemically modified with MTSSL, a Cys-reactive spin-label, and observed using electron paramagnetic resonance (EPR) spectroscopy. The EPR spectrum is sensitive to the label environment and reports on the mobility of the residue to which the spin label is attached. While pH-dependent differences in mobility were apparent at aL195 and aV86/I161, the multi-component spectra indicated the presence of unreacted and/or off-target spin label preventing conclusive analysis of the data. Optimizing purification methods to remove the contaminating components may improve the quality of the data.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 2:20pm - 2:40pm PDT
123 Zeis Hall

2:20pm PDT

Synthesis Of Pyrazoline Derivatives From Chalcones
Synthesis of pyrazoline derivatives has been an active field of research due to the established biological and pharmaceutical activities of these compounds such as antibacterial, anti-inflammatory, and anticancer properties. Pyrazoline derivatives can be produced from the cyclization of chalcones with hydrazine hydrate and an aryl aldehyde. The goal of this project is aza-Michael addition of aliphatic amines to various α,β unsaturated carbonyl compounds as a novel approach for pyrazoline synthesis using ionic solvents. Previous research has proven that the use of DBU (1,8-diazabicyclo[5.4.0]-undec7-ene-8) as a catalyst/promoter for aza-Michael addition can provide high yields and has the additional advantage of good reusability. However, the “one pot” total synthesis of pyrazoline derivatives has proven to produce low yields. In this project, the reaction between chalcone (1a-d), hydrazine hydrate, and benzaldehyde with [DBU][Ac] (1,8-diazabicyclo[5.4.0]-undec7-en-8-ium acetate) acting as a catalyst was found to successfully synthesize various pyrazoline derivatives (2a-d). Compound 2b had the highest yield of the four compounds (58.6%) and further research will need to be completed to maximize the yields of the products. The successful synthesis of the derivatives provides a new methodology for the creation of pyrazoline, and supplies incentive for further investigation of the use of ionic liquids as catalysts in the addition of nitrogenous groups to α,β unsaturated carbonyl compounds.

Moderators
Speakers
Sponsors

Tuesday April 24, 2018 2:20pm - 2:40pm PDT
202 Zeis Hall