Browsing by Subject "Department of Chemistry"
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Item Application of the Dieckmann Condensation to Pyrrole Diesters(2012-04-18) Choi, JuaThe Dieckmann condensation is commonly used in preparation of cyclic indole. The heterocyclic indole can be biologically active against cancer. The application of the Dieckmann condensation in the formation of five-membered pyrrole rings has not been previously reported in literature, making the procedure novel. Using extra equivalents of AlCl3 and Et3N allowed for the successful synthesis of cyclized pyrroles. Whether another choice of Lewis acids may also succeed the reaction remains to be discovered.Item Changes of carbonyl bond stretch frequency of Vaska’s complex with added bromine and sulfur respectively in different solvents(2012-04-18) Muthu, NagilthesVaska’s complex is a catalyst molecule that is important for improving the rates of chemical reactions. This molecule consists of organic (carbon-based) regions surrounding an iridium metal atom. The interactions of this complex with reactants during a catalytic process involve binding of reactants to the metal and rearrangement of the surrounding organic regions. Throughout this process, the solvent in which the reaction is occurring is also rapidly rearranging. These rearrangements have recently been studied by the Massari group at the University of Minnesota (Jones, B. H.; Huber, C. J.; Massari, A. M. Solvation Dynamics of Vaska’s Complex by 2D-IR Spectroscopy J. Phys. Chem. C 2011, 115, 24813-24822.). The role of solvents in the catalytic reactions of Vaska’s complex can be further studied by Fourier transform IR (FTIR) spectroscopy, which measures the molecular vibrations of the molecules at work. In this project, bromine and sulfur were bound to the Vaska’s complex in a broad range of solvents. The carbonyl bond stretch frequency in the Vaska’s complex in these solutions was analyzed using FTIR spectroscopy to determine if there was a solvent dependency. The solvent dependence of the carbonyl stretch had been previously observed to differ by about 10 cm-1 in different solvents. Addition of sulfur and bromine respectively to Vaska’s complex increased the carbonyl stretching vibration. Addition of bromine increased the carbonyl vibration more than the addition of sulfur to the Vaska’s complex, indicating that the bond between carbon from carbonyl and iridium was weakened to a greater extent by the bromine. Surprisingly, it was found that the frequency of the carbonyl was nearly insensitive to the nature of the solvent, while the sulfur complexes experienced moderate frequency shifts. This was explained by considering the differences in the way that the bromine and sulfur bind to the iridium metal.Item Characterizing the pH Dependence of Surface Charge for Silica Nanoparticles Made by Amino Acid Synthesis(2010-04-21) Zhang, LiangSilica nanoparticles are silica spheres in the micron size range. Because of their shape and ordered arrangement, these nanoparticles serve important purposes in high-tech industries and modern applications such as cancer therapy, drug and DNA delivery systems, ultrasensitive analysis, and nanoparticle films. Applications depend on order in packing of nanoparticles, which in turn depends on particle charge. Silica nanoparticles were synthesized using published methods and the pH of the solution bathing the nanoparticle was altered. The nanoparticle solutions were then characterized by size with SAXS lighting scattering and by surface charge with an electrophoretic method. Though zeta-potential tests provided variable data with each batch of particles, the overall pattern was consistent. It was found that zeta potential decreases as pH becomes more acidic.Item Chemical Products from Peat Project(University of Minnesota Duluth, 1957-04) Passer, MosesItem Comparison of carbonylation in young and old rat skeletal muscle(2011-04-13) Willard, IsaacProteins, DNA, and lipids in most tissues become carbonylated due to oxidative stress. Skeletal muscles are particularly susceptible to such carbonylation because of the conversion from metabolic energy to mechanical energy during contraction. This project focuses on the relative levels of carbonylation in intermyofibrillar mitochondria (IFM), the subsarcolemmal mitochondria (SSM), the cytoplasm, and the extracellular space of skeletal muscle. The morphology and function of muscle cells change in response to ageing and development. To measure the variance in carbonylation patterns with respect to both development and age, muscle tissue from young and old animals is analyzed. A labeling agent is used to label mitochondria red and carbonyl groups green. Confocal microscopy can take images of the labeled tissue and overlay them to show the mitochondria that have been carbonylated. The amounts of uncarbonylated and carbonylated mitochondria are compared between young and old tissue to determine how carbonylation changes with age.Item Computational Modeling of Protein Kinase A and Comparison with Nuclear Magnetic Resonance Data(2009-10-07) Shi, Lei; Veglia, GianluigiProtein phosphorylation is fundamental in the modulation of myocardial contractility. Sarcoendoplasmic reticulum Ca2+ ATPase(SERCA) removes cytosolic Ca2+ to initiate relaxation, but the regulatory protein, phospholamban(PLN), decreases SERCA’s affinity for free Ca2+. Phosphorylation of PLN by Protein Kinase A (PKA) induces a relief of inhibition on SERCA and augments the rate of SERCA Ca2+ uptake. Here, we studied the interaction between PKA and PLN by nuclear magnetic resonance (NMR), computational docking and molecular dynamics (MD) simulations. Comparative simulations of PKA apo, binary and ternary states were performed, which provided molecular details to understand the mechanism of PKA substrate recognition.Item Condensation reaction of Indole and ketone(2012-02-20) Gao, SimingThe subject of this project is the study of condensation reaction of indole and ketone. Indole and indole derivatives are widely applied to material sciences, agrochemicals, and pharmaceuticals1. This research topic needs to be studied and supported by a large amount of date and hundreds of experiments, because the indole and ketone could be reacted in different solvents with different ratios and reaction conditions. For this limited-time UROP topic, which is also a small part of this huge project, two specific mole ratios are chosen for indole and ketones, which are 1:2 and 2:1 under acidic conditions. The emphasis is on the reaction of 2:1 indole and ketone reaction, in which the products are bisindolylmethanes (BIMs). As an important class of indole derivatives, BIMs are “most active cruciferous substances for promoting beneficial estrogen metabolism and inducing apoptosis in human cancer cells” as written in Green Protocol for the Synthesis of Bisindolylmethanes and Evaluation of Their Antimicrobial Activities2. In this UROP project, the most straightforward method is chosen to synthesize BIMs, which is the acid-catalyzed condensation reaction of indole and ketones.Item Coupling and Metathesis Copolymerization of Conjugated Polymers for Organic Photovoltaics(2011-04-13) Slowinski, BradleyIn order to meet an ever increasing energy demand, photovoltaic technologies must be explored. As a low cost alternative to inorganic photovoltaics, organic photovoltaics offer a unique combination of flexibility and processability. Nevertheless, these devices should not be viable until their efficiency is improved.Item Department of Chemistry Seminar Schedule 2002 Fall(2002) University of Minnesota Duluth. Department of ChemistryItem Department of Chemistry Seminar Schedule 2003 Fall(2003-10-08) University of Minnesota Duluth. Department of ChemistryItem Department of Chemistry Seminar Schedule 2003 Spring(2003) University of Minnesota Duluth. Department of ChemistryItem Department of Chemistry Seminar Schedule 2004 Fall(2004) University of Minnesota Duluth. Department of ChemistryItem Department of Chemistry Seminar Schedule 2004 Spring(2004-01-30) University of Minnesota Duluth. Department of ChemistryItem Development of a novel fixation method for mitochondria(2011-04-13) Doenges, Jack; Kostal, VratislavAt biological pH, isolated mitochondria carry a negative charge on their surface as a result of the chemical composition of the ionizable groups on their surface. Capillary Electrophoresis with Laser Induced Fluorescence Detection (CE-LIF) has been shown to separate and detect fluorescently labeled individual mitochondria based on their electrophoretic properties. This technology has been used to provide insights into the role of mitochondria in aging and disease. A problem exists, however, with the stability of isolated mitochondria. CE-LIF analysis of mitochondria must be done within a few hours after the sample preparation. Otherwise, the electrophoretic properties of a mitochondrial preparation begin to change. This prevents collaboration among laboratories and limits the number of tests that can be done on a given mitochondrial preparation. Here, I present a method for stabilizing mitochondria using formaldehyde, a reagent commonly used for cell and tissue preservation. In this project I explore the effects of formaldehyde treatment on stabilizing the electrophoretic properties of isolated mitochondria. Isolated mitochondria from L6 cells are treated with 4% formaldehyde and the distributions of the electrophoretic mobility are measured using CE-LIF and compared to those obtained from untreated mitochondria samples. If successful, stable samples of mitochondria will allow long-term storage and transportation of mitochondria, which will lead to advancements in the fields of mitochondrial research and particle separation by CE-LIF.Item Effect of the Cooling Coefficient on Efficiency Loss in SFC(2012-04-18) Lusk, RyanSupercritical fluid chromatography (SFC) is becoming a rapid alternative to high performance liquid chromatography (HPLC) because the lower viscosity and higher diffusivity of the mobile phase due to critical conditions enables faster separations and the ability to use smaller stationary phase particle sizes. However, radial temperature gradients that form from expansion of the mobile phase across the column reduce its efficiency. The net cooling coefficient of the mobile phase at the column outlet is a major factor controlling that temperature drop. The experimental correlation between the net cooling coefficient and efficiency loss was examined by performing two series of experiments: one where the oven temperature was held constant at 50.0 °C and the column outlet pressure was varied to yield nominal net cooling coefficients ranging from 0.10 to 0.25 K/bar and another where the column outlet pressure was held constant at 148 bar and the oven temperature was varied to yield the same range of nominal net cooling coefficients. Plate height curves of both sets of experiments were produced to examine column efficiency. It was found that the elution profiles that shared the same net cooling coefficient but had different experimental conditions had nearly identical column efficiencies, indicating that the net cooling coefficient strongly predicts column efficiency.Item Efficient charge transfer from excited state dye molecules into nanoparticles as a model for dye sensitized solar cells(2011-11) Hue, Ryan; Vatassery, Rajan; Hinke, Jon; Mann, Kent; Blank, David; Gladfelter, WayneWe deconstruct the DSSC and focus on the sensitization mechanism to extract a thorough understanding of the charge separation process. Our study of the dye's interactions with the nanoparticles provides details about the attachment, the surface environment and the ability for the dyes to inject electrons in competition with loss mechanisms.Item Exploration of Small Molecule Reduction via Transition Metal Complexes Supported by Novel Trianionic Cryptand Ligand Systems(2011-04-13) Mullikin, AlexThe reductions of small molecules (CO2, CO, N2, and O2) have been studied as an interesting, cheap method for the formation of valuable chemical feedstocks. While prices of petroleum on the rise, processes such as the reduction of CO-2 into methanol are necessary to ease our use from non-renewable sources of fuel. To achieve these reductive processes, my research has been focused on the design and synthesis of novel ligands. Following the synthesis of these novel ligands, they will be metallated with late transition metals (Zn, Co, Fe, and Mn). A Zn complex which is supported by a trianionic, tetradentate cryptand ligand has been synthesized and characterized with X-Ray Crystallography. This metallated ligand, along with the fore mentioned metals, will be reacted with various small molecules and analyzed for the ligand’s ability to reduce these molecules.Item Formation and Aging of Ferrihydrite Nanoparticles in the Presence of Organics(2010-10-11) Weber, Nolan R.The object of this research project is to determine how adding organic compounds during crystal formation affects the physical properties of the ferrihydrite crystals that are formed. Ferrihydrite is a nanomaterial with no bulk counterpart and forms naturally in nature. Through these experiments, we hope to elucidate more details about out how the formation occurs in nature. Once we figure out how the formation occurs, we can manipulate it for various industrial and environmental applications.Item Improved Fermentation Through Removal of Acetic Groups for the Increased Production of Ethanol(2011-04-13) Frederick, JosephAcetic groups have been known to reduce the production of ethanol during fermentation. Various chemical treatments were conducted on an artificial fermentation liquor in an attempt to reduce the amount of acetic groups in the solution. These treatments included calcium hydroxide and zeolites (aluminum and silicon structures). It was found that a zeolite with a silicon to aluminum ratio of 140 removed the most acetic groups (12.52%) and a zeolite with a silicon to aluminum ratio of 29 removed less (11.33%). However, the zeolite with the silicon to aluminum ratio of 29 managed to have a higher conversion of dextrose to ethanol than the zeolite with a silicon to aluminum ratio of 140.Item In vitro Toxicity Study of Noble Metal Nanoparticles with Varied Size, Geometry and Surface Chemistry(2010-04-21) Liu, ZhenThe study of nanotoxicity is essential to evaluate the safety of human consumption and to inform the design of nanomaterials for biomedical uses. In this work, living cells were exposed to noble metal nanoparticles with varied size, geometry and surface chemistry in order to determine the effects these properties have on noble metal nanoparticle uptake and toxicity. Nanoparticles were synthesized using a variety of methods including surfactant templating, secondary deposition, and Ostwald Ripening under controlled light conditions in order to achieve nanomaterials with varied size and geometry. Surface chemistry was varied by surfactant exchange using charged thiols such as 11- mercaptoundecanoic acid and 11-mercaptoundecylamine to replace the initial surfactants, thus yielding nanoparticles with negative or positive z-potentials. Cellular uptake was measured using ICP-AES in exposed cells. Toxicity was assessed by MTT and hemolysis assays. In fact, both cellular uptake of nanoparticles and viability were dependent on the physical characteristics of the nanomaterials varied in this study.