Chemistry Commons^™

Search For Lowest-Energy Structure Of Zintl Dianion Si122-, Ge122-, And Sn122-, Nan Shao, Satya S. Bulusu, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We perform an unbiased search for the lowest-energy structures of Zintl dianions (Si₁₂^2-, ₁₂^2-, and ₁₂^2-), by using the basin-hopping (BH) global optimization method combined with density functional theory geometric optimization. High-level ab initio calculation at the coupled-cluster level is used to determine relative stabilities and energy ranking among competitive low-lying isomers of the dianions obtained from the BH search. For ₁₂^2-, all BH searches (based on independent initial structures) lead to the same lowest-energy structure _12a^2-, a tricapped trigonal prism (TTP) with C_s group symmetry. Coupled-cluster calculation, …

Mechanistic Studies On The Electrochemistry Of Glutathione And Homocysteine, Olufemi Oyesanya

Theses and Dissertations

This research work has investigated the electrochemistry of glutathione (GSH)and homocysteine (HCSH) in order to develop sensors for these biological thiols.Ru(bpy)₃³⁺ and IrCl₆²⁻ have been used as mediators for the electrooxidation of GSH andHCSH because direct oxidation of these thiols is slow at most conventional electrodes.The electrochemical detection of GSH and HCSH has been pursued because of their biological roles.

Concerted proton electron transfer (CPET) and stepwise proton electron transfer(PT/ET) pathways have been observed in the electrooxidation of GSH and HCSH.Oxidation of GSH by Ru(bpy)₃³⁺ carried out in deuterated and undeuterated buffered (pH= pD …

Co2 Fixation Kinetics Of Halothiobacillus Neapolitanus Mutant Carboxysomes Lacking Carbonic Anhydrase Suggest The Shell Acts As A Diffusional Barrier For Co2, Zhicheng Dou, Sabine Heinhorst, Eric B. Williams, C. Daniel Murin, Jessup M. Shively, Gordon C. Cannon

Faculty Publications

The widely accepted models for the role of carboxysomes in the carbon-concentrating mechanism of autotrophic bacteria predict the carboxysomal carbonic anhydrase to be a crucial component. The enzyme is thought to dehydrate abundant cytosolic bicarbonate and provide ribulose 1.5-bisphosphate carboxylase/oxygenase (RubisCO) sequestered within the carboxysome with sufficiently high concentrations of its substrate, CO₂, to permit its efficient fixation onto ribulose 1,5-bisphosphate. In this study, structure and function of carboxysomes purified from wild type Halothiobacillus neapolitanus and from a high CO₂-requiring mutant that is devoid of carboxysomal carbonic anhydrase were compared. The kinetic constants for the carbon …

One-Pot Enol Silane Formation-Mukaiyama Aldol-Type Addition To Dimethyl Acetals Mediated By Tmsotf, C. Wade Downey, Miles W. Johnson, Kathryn J. Tracy

Chemistry Faculty Publications

Various ketones, esters, amides, and thioesters add in high yield to dimethyl acetals in the presence of silyl trifluoromethanesulfonates and an amine base. Acetals derived from aryl, unsaturated, and aliphatic aldehydes are all effective substrates. The reaction proceeds in a single reaction flask, with no purification of the intermediate enol silane necessary.

Dioxidobis(2-Oxo-1,2-Dihydropyridin-3-Olato)­Molybdenum(Vi), Manoj Trivedi, Daya Pandey, Nigam Rath

Chemistry & Biochemistry Faculty Works

In the title compound, [Mo(C5H4NO2)2O2], the MoVI atom exhibits a distorted octa­hedral coordination geometry formed by two terminal oxo ligands and two monoanionic O,O-bidentate pyridinone ligands. The two terminal oxo ligands lie in a cis arrangement, the ketonic O atoms of the pyridinone ligands are coordinated trans to the oxo ligands and the deprotonated hydroxyl O atoms are located trans to each other. The crystal structure contains inter­molecular N-H...O hydrogen bonds, C-H...O contacts and face-to-face [pi]-[pi] stacking inter­actions with an inter­planar separation of 3.25 (1) Å.

Diethyl 2-[(4-Nitro­Phen­Yl)(4-Phenyl-1,2,3-Selenadiazol-5-Yl)Meth­Yl]Malonate, A. Marx, S. Saravanan, S. Muthusubramanian, V. Manivannan, Nigam Rath

Chemistry & Biochemistry Faculty Works

In the title compound, C22H21N3O6Se, the heterocyclic ring makes dihedral angles of 50.03 (11) and 67.75 (11)°, respectively, with the benzene and phenyl rings. The terminal C atoms of the ester groups are disordered over two positions: the site occupancies for the C atoms are 0.62 (3)/0.38 (3) and 0.48 (3)/0.52 (3). In the crystal structure, weak intra- and inter­molecular C-H...O inter­actions are observed.

Dirhenium Carbonyl Complexes Bearing 2-Vinylpyridine, Morpholine And 1-Methylimidazole Ligands, Shariff E. Kabir, Faruque Ahmed, Anamika Das, Mohammad R. Hassan, Daniel T. Haworth, Sergey V. Lindeman, Tasneem Siddiquee, Dennis W. Bennett

Chemistry Faculty Research and Publications

Treatment of the labile compound [Re₂(CO)₈(MeCN)₂] with 2-vinylpyridine in refluxing benzene affords exclusively the new compound [Re₂(CO)₈(μ-η¹:η²-NC₅H₄CHCH₂)] (1) in 39% yield in which the μ-η¹:η²-vinylpyridine ligand is coordinated to one Re atom through the nitrogen and to the other Re atom via the olefinic double bond. Reaction of [Re₂(CO)₈(MeCN)₂] with morpholine in refluxing benzene furnishes two compounds, [Re₂(CO)₉(η¹-NC₄H₉O)] …

Stability And Equation Of State Of A Nanocrystalline Ga-Ge Mullite In A Vitroceramic Composite: A Synchrotron X-Ray Iffraction Study, Kristina E. Lipinska-Kalita, Patricia Kalita, Cedric Gobin, Oliver Hemmers, Thomas Hartmann, Gino Mariotto

Environmental Studies Faculty Publications

Synchrotron x-ray diffraction and diamond anvil cell techniques were used to characterize the phase transformations and to evaluate the structural stability at elevated pressures of a developed nanocrystalline composite. The optically transparent material was built of a germanium oxide-based amorphous host matrix with homogeneously dispersed 13±3 nm Ga-Ge mullite-type nanocrystals, which had a structure similar to the conventional Al₂O₃-SiO₂ mullite. The equation of state of the nanocrystals and the overall structural integrity of the nanocomposite were investigated in quasihydrostatic conditions on compression to 36 GPa and on the following decompression to ambient conditions. The overall …

Progress Toward Cariporide Analogs For Sodium-Proton Exchange Inhibition, Jessica Moore, Mark Graves Ii, Jacob A. Vervynckt, William Harley, Fredric Gorin, Hasan Palandoken

Chemistry and Biochemistry

The sodium proton exchanger (NHE) is particularly important in maintaining the intracellular pH in human heart and brain. Under anaerobic conditions (i.e., ischemia), a shift from oxidative to nonoxidative glycolysis occurs. The resultant decrease in the intracellular pH activates NHE, which increases the intracellular sodium, initiating the sequence of physiological events that lead to cell death. Thus, there has been great interest in the development of compounds that inhibit NHE. Indeed, potent NHE inhibitors are available. However, a fundamental impediment to the field is the delivery of these compounds to poorly vascularized tissues during the early phases of ischemia when …

The Effects Of Pc-Based Laboratories On Student Learning, Lester L. Pesterfield, Stuart Burris, Darwin B. Dahl, Hasan Palandoken, Jacqueline Pope-Tarrence

Chemistry and Biochemistry

The Department of Chemistry at Western Kentucky University recently incorporated a net-worked MeasureNet data acquisition and analysis system into in the second semester General Chemistry laboratories. Our investigation team has conducted a study to evaluate the effects of the MeasureNet system on student learning and performance on a Beer's Law laboratory. We focused on two phenomena: the effect of the MeasureNet system on 1) student learning of specific content material and 2) student interest in chemistry and science in general. The study involved a MeasureNet system group (employing a UV-Vis spectrometer and colorimeters) and a control group (employing traditional Spectronic …

Quantitative Measure Of Cytotoxicity Of Anticancer Drugs And Other Agents, Zhimin Tao, Eyone Jones, Jerry Goodisman, Abdul-Kader Souid

Chemistry - All Scholarship

Many anticancer drugs act on cancer cells to promote apoptosis, which includes impairment of cellular respiration (mitochondrial O ₂ consumption). Other agents also inhibit cellular respiration, sometimes irreversibly. To investigate the sensitivity of cancer cells to cytotoxins, including anticancer drugs, we compare the profiles of cellular O ₂ consumption in the absence and presence of these agents. Oxygen measurements are made at 37 °C, using glucose as a substrate, with [O ₂] obtained from the phosphorescence decay rate of a palladium phosphor. The rate of respiration k is defined as -d[O ₂]/dt in a sealed container. Different toxins …

Chemistry & Biochemistry Newsletter, Department Of Chemistry & Biochemistry, South Dakota State University

Chemistry & Biochemistry Newsletter: 2002-2015

Inside:

Page 2 Photodynamic Therapy Offers New Approach to Cancer

Page 3 Chemistry Professor Recognized by Peers as Member of the Year; Department Head Joins NSF Committee

Page 4 Retired SDSU Dean Honored for Distance Education Alliance; Miller receives Edward Patrick Hogan Award; Freshman Chemistry Major Honored

Page 5 2008 Chemistry and Biochemistry Graduates

Page 6 Scholarships and Awards

Spectroscopy Is Applied Quantum Mechanics. Part 3: Introduction To Quantum Mechanics, David W. Ball

Chemistry Faculty Publications

The article discusses the pioneering work of Erwin Schrödinger on wave mechanics that forms the basis of modern understanding in subatomic behavior. Schrödinger introduced a second-order differential equation that had to be solved to explain the nature of the hydrogen atom. He also demonstrated that the matrix mechanics of Heisenberg and Born were mathematically equivalent and developed the concept of perturbation theory to explain the Stark effect.

Synthesis And Characterization Of Two Metallic Spin-Glass Phases Of Femo₄Ge₃, Peter J. Baker, Peter D. Battle, Stephen J. Blundell, Fernande Grandjean, Thomas M. Lancaster, Gary J. Long, Sophie E. Oldham, Timothy John Prior

Chemistry Faculty Research & Creative Works

Polycrystalline samples of FeMo₄Ge₃ have been synthesized by the reduction of an oxide mixture at 1248 K and characterized by a combination of diffraction, muon spin relaxation (µ⁺SR), Mössbauer spectroscopy, magnetometry, transport, and heat-capacity measurements. The compound adopts a tetragonal W₅Si₃ structure (space group I₄/mcm); the iron and molybdenum atoms are disordered over two crystallographic sites, 16k and either 4a or 4b. The synthesis conditions determine which fourfold site is selected; occupation of either leads to the presence of one-dimensional chains of transition metals in the structure. In both cases, …

Fluorescence Characteristics Of Triazine-Manufacturing Wastewater, Lin Huang, Shuyan Qiu, Neissa Pinzon, Li-Ta Lien, Lu-Kwang Ju

Chemical, Biomolecular, and Corrosion Engineering Faculty Research

Samples taken at different points in the wastewater treatment process of a triazine-manufacturing plant were scanned by fluorescence spectroscopy, in the wavelength range of 200-900 nm. Reproducibly, the fluorescence spectra revealed one single major peak at excitation and emission wavelengths of 258 and 370 nm respectively. Aqueous solutions of purified active compounds, including Atrazine, Propazine, Simazine, Terbuthylazine, Metolachlor, and Benoxacor, were also scanned. No significant fluorescence was observed in these standard solutions at concentrations up to 100 mg/L. Selected plant samples as well as standard solutions of Atrazine, Metolachlor, and toluene were further analyzed using high-performance liquid chromatography with absorbance …

Real-Time Analysis And Investigation Of The Mechanism Of The Palladium On Carbon Catalyzed Isomerization Of Megestrolacetate, Charlene K. Wiglesworth

Masters Theses

Megestrol Acetate is a semi-synthetic steroid hormone of the progestin family and currently used as a drug therapy in many areas including treatments of cancers and AIDS. The final step to form the bulk drug is an isomerization using palladium on carbon with cyclohexene as an activator. This step is sensitive to catalyst quality and is hazardous to sample because of the reactivity of the catalyst. Physical and catalytic properties of the catalyst were evaluated, as were the effects of solid support and different washing strategies. Response of the reaction mixture to catalyst poisons was studied as a function of …

N-(Deoxyadenosine-8-Yl)-4-Aminobiphenyl Adduct Formation In Vitro On Tp53 Exon7 Genome: Quantitation By Lc-Esi-Ms/Ms, Paul René Knoll

Masters Theses

The p53 protein has been documented to be mutated in more than 50% of late stage bladder cancers and tobacco causes 50% of all bladder tumors. The 4- arninobiphenyl (ABP) carcinogen comprises 5 ng per cigarette in the smoke and is a known bladder carcinogen. The research goal in the present study was to compare the reactivity of rat liver S-9 fraction activated 4-arninobiphenyl with the 45-mer sense strand of the TP53 exon7 gene to the respective anti-sense strand. The specific and sensitive technique of LC-tandem mass spectrometry (LC-MS/MS) was used for quantitation. The authentic standard of N-(adenine-8yl-)-4-arninobiphenyl (A-ABP) …

Ionic Liquids: Syntheses, Characterization And Applications In Analytical Chemistry, Pritesh S. Sharma

Chemistry & Biochemistry Theses - Archive

Multifunctional ionic liquids (esp. dicationic and dianionic) have been shown to have a greater range of physical properties than most traditional, singly charged ILs. In this work, 28 novel tricationic ILs with specific structural variations have been synthesized in order to investigate the effect on their physicochemical properties. It was observed that the physicochemical properties can be varied to a greater extent in tricationic ILs than in traditional ILs. The central core of the tricationic IL itself can have different degrees of flexibility and these moieties can be altered as can the charge carrying groups to produce ILs with the …

Fabrication Of Magnetic Porous Hollow Silica Drug Carriers, Charles J. O'Connor, Gabriel Caruntu

Chemistry Faculty Publications

Magnetic porous hollow silica nanosphere is a new class of structured nanomaterials for drug delivery. In this paper, we report a synthesis of magnetic porous hollow silica nanospheres MPHSNs using CaCO3 /Fe3O4 composite nanoparticles and cationic surfactant double templates. Fe3O4 nanoparticles were first mixed into CaCO3 using rotating packed bed forming CaCO3 /Fe3O4 composite nanoparticles. Tetraethoxysilane was then added as precursor to form silica layer on the surface of CaCO3 /Fe3O4 composite nanoparticles, while hexadecyltrimethylammonium bromide was used as a second template to direct the formation of porous silica shells. After the calcination of the surfactants and etching away CaCO3, …

Metal Coordination And Cis-Trans Isomerisation Of Benzene Dihydrodiols, Catriona O'Meara

Masters

Abstract In this thesis, a viable route for conversion of arene cis-dihydrodiols to their trans isomers was investigated. The cis-dihydrodiols can be produced by large scale fermentation but their trans analogues are not accessible using this approach. The trans dihydrodiols are potentially important chiral building blocks in synthetic chemistry particularly because they have the advantage that they are more stable than the cis-isomers. The principal aim of this work was to carry out parallel studies to inform the development of the synthetic pathway under study by; (a) synthesis of organometallic and organic intermediates and products and, (b) investigation of the …

Volume 01, Jessica Fields, Stephanie Neeley, Derek W. Hambright, Mary E. Lehman, Andrew R. Grzankowski, Zachary Johnson, Boone M. Prentice, Ashley M. Swandby, Victoria Morgan, Katie Williamson, Kristine G. Bender, Katelyn N. Romaine, D. Nicole Swann, Jessica Fox, Mike Mcateer, Alex Grabiec, Laura Nodtvedt, Nick Costa, Rachel Wolfe, Zack Dalton

Incite: The Journal of Undergraduate Scholarship

Introduction from Dean Dr. Charles Ross

Three Decades of Digging: Undergraduate Archeology at Longwood by Jessica Fields and Stephanie Neeley

Interactions of Allelopathy and Heat Stress in Plants by Derek W. Hambright and Mary E. Lehman

Inertial Electrostatic Confinement D-D Fusion Device: Construction and Simulation by Andrew R. Grzankowski

Shackled Nim by Zachary Johnson

Development of GC-MS and Chemometric Methods for the Analysis of Accelerants in Arson Cases by Boone M. Prentice

A Comparison of Image Analysis Methods in cDNA Microarrays by Ashley M. Swandby

Perceived Sexual Activity of Short and Long-Term Relationships by Victoria Morgan and Katie Williamson

Elderly …

Comparison Of Polymerase Chain Reaction And Bacterial Culture For Salmonella Detection In The Muscovy Duck In Trinidad And Tobago, Joanne Rampersad-Ammons, Jenelle Johnson, Gabriel Brown, Michael S. Samlal, David R. Ammons

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Objectives: The purpose of this study was to investigate the presence and serovar identity of Salmonella, at the national level, in farmed Muscovy ducks (Cairina moschata) in Trinidad and Tobago, and to compare the relative benefits of bacterial culture to those of polymerase chain reaction (PCR) for use in the routine detection and surveillance of Salmonella in these ducks.

Methods: From March-September 2003, 110 fecal samples were collected from 82 farms across the islands of Trinidad and Tobago. Salmonella was isolated from fresh and frozen samples and the serotype of each was determined through bacterial culture. An in-house, nested PCR …

Thermal Stability And Degradation Kinetics Of Polystyrene/Organically-Modified Montmorillonite Nanocomposites, Grace Chigwada, Everson Kandare, Dongyan Wang, Stephen Majoni, Darlington Mlambo, Charles A. Wilkie, Jeanne M. Hossenlopp

Chemistry Faculty Research and Publications

Organically-modified montmorillonite (MMT) clays have been prepared using ammonium salts containing quinoline, pyridine, benzene, and styrenic groups. The nanocomposites were prepared by melt blending and the formation of nanocomposites was characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal stability and flammability were evaluated by thermogravimetric analysis (TGA) and cone calorimetry measurements, respectively. The presence ofmodified MMT at 5% loading resulted in significant improvement in thermal stability compared to the virgin polymer. Effective activation energies for mass loss were determined via a model-free isoconversional approach from TGA data obtained under N₂ and under air. The additives served …

The Quenching Of Isopropyl Group Rotation In Van Der Waals Molecular Solids, Xianlong Wang, Arnold L. Rheingold, Antonio G. Dipasquale, Frank B. Mallory, Clelia W. Mallory, Peter A. Beckmann

Chemistry Faculty Research and Scholarship

X-ray diffraction experiments are employed to determine the molecular and crystal structure of 3-isopropylchrysene. Based on this structure, electronic structure calculations are employed to calculate methyl group and isopropyl group rotational barriers in a central molecule of a ten-molecule cluster. The two slightly inequivalent methyl group barriers are found to be 12 and 15 kJ mol(-1) and the isopropyl group barrier is found to be about 240 kJ mol(-1), meaning that isopropyl group rotation is completely quenched in the solid state. For comparison, electronic structure calculations are also performed in the isolated molecule, determining both the structure and the rotational …

Fluorenes And Styrenes By Au(I)-Catalyzed Annulation Of Enynes And Alkynes, David J. Gorin, Iain D.G. Watson, F. Dean Toste

Chemistry: Faculty Publications

Intermolecular annulation of enynes and propargyl esters to selectively produce styrenes or fluorenes is reported. The divergent arene syntheses involve a Au-catalyzed, two-pot, multistep process proceeding by cis-diastereoselective cyclopropanation, cycloisomerization, and, finally, annulation or elimination.

Comment On “Contact Conditions For The Charge In The Theory Of The Electrical Double Layer”, Douglas Henderson, L. B. Bhuiyan

Faculty Publications

Exact results in any field, including statistical mechanics, are both aesthetically pleasing and very valuable in assessing theoretical approximations.

Aequorin And Obelin Mutants With Differing Wavelengths And Bioluminescence, Sylvia Daunert, Sapna K. Deo, Emre Dikici, Laura Rowe

Chemistry Faculty Patents

The invention relates to aequorin and obelin mutants whose emission is shifted with respect to wild type. The shift in emission is accomplished using a combination of mutations of amino acids within aequorin or obelin that affect bioluminescence; use of different types of chromophores, i.e., coelenterazines with variable emission characteristics; and modifications of the photoprotein with fluorophores that will allow for emission of light at longer wavelengths as a result of energy transfer. Additionally, an assay employing aequorin mutants to test for HIV-1 protease inhibitors is disclosed.

Structures And Relative Stability Of Medium- And Large-Sized Silicon Clusters. Vi. Fullerene Cage Motifs For Low-Lying Clusters Si39, Si40, Si50, Si60, Si70, And Si80, Soohaeng Yoo, N. Shao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We performed a constrained search, combined with density-functional theory optimization, of low-energy geometric structures of silicon clusters Si₃₉, Si₄₀, Si₅₀, Si₆₀, Si₇₀, and Si₈₀. We used fullerene cages as structural motifs to construct initial configurations of endohedral fullerene structures. For Si₃₉, we examined six endohedral fullerene structures using all six homolog C₃₄ fullerene isomers as cage motifs. We found that the Si₃₉ constructed based on the C₃₄(C_s:2) cage motif results in a new leading candidate for the lowest-energy structure …

Mesoporous Silica Nanoparticles Inhibit Cellular Respiration, Zhimin Tao, Tewodros Asefa, Cole Duncan, Abhishek Anan, Jerry Goodisman

Chemistry - All Scholarship

We studied the effect of two types of mesoporous silica nanoparticles, MCM-41 and SBA-15, on mitochondrial O ₂ consumption (respiration) in HL-60 (myeloid) cells, Jurkat (lymphoid) cells, and isolated mitochondria. SBA-15 inhibited cellular respiration at 25-500/ μg/mL; the inhibition was concentration-dependent and time-dependent. The cellular ATP profile paralleled that of respiration. MCM-41 had no noticeable effect on respiration rate. In cells depleted of metabolic fuels, 50 μg/mL SBA-15 delayed the onset of glucose-supported respiration by 12 min and 200 μg/mL SBA-15 by 34 min; MCM-41 also delayed the onset of glucose-supported respiration. Neither SBA-15 nor MCM-41 affected cellular glutathione. Both …

Towards The Rational Design Of Mri Contrast Agents: Electron Spin Relaxation Is Largely Unaffected By The Coordination Geometry Of Gadolinium(Iii)–Dota-Type Complexes, Alain Borel, Jonathan F. Bean, Robert B. Clarkson, Lothar Helm, Loïck Moriggi, A. Dean Sherry, Mark Woods

Chemistry Faculty Publications and Presentations

Electron‐spin relaxation is one of the determining factors in the efficacy of MRI contrast agents. Of all the parameters involved in determining relaxivity it remains the least well understood, particularly as it relates to the structure of the complex. One of the reasons for the poor understanding of electron‐spin relaxation is that it is closely related to the ligand‐field parameters of the Gd³⁺ ion that forms the basis of MRI contrast agents and these complexes generally exhibit a structural isomerism that inherently complicates the study of electron spin relaxation. We have recently shown that two DOTA‐type ligands could be …