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Chemistry

Faculty Publications

Series

2010

Articles 1 - 19 of 19

Full-Text Articles in Physical Sciences and Mathematics

Systematic Approach To Electrostatically Induced 2d Crystallization Of Nanoparticles At Liquid Interfaces, Sumit Kewalramani, Suntao Wang, Yuan Lin, Huong Giang Nguyen, Qian Wang, Masafumi Fukuto, Lin Yang Nov 2010

Systematic Approach To Electrostatically Induced 2d Crystallization Of Nanoparticles At Liquid Interfaces, Sumit Kewalramani, Suntao Wang, Yuan Lin, Huong Giang Nguyen, Qian Wang, Masafumi Fukuto, Lin Yang

Faculty Publications

We report an experimental demonstration of a strategy for inducing two-dimensional (2D)crystallization of charged nanoparticles on oppositely charged fluid interfaces. This strategy aims to maximize the interfacial adsorption of nanoparticles, and hence their lateral packing density, by utilizing a combination of weakly charged particles and a high surface charge density on the planar interface. In order to test this approach, we investigated the assembly of cowpea mosaic virus (CPMV) on positively charged lipid monolayers at the aqueous solution surface, by means of in situX-ray scattering measurements at the liquid–vapor interface. Theassembly was studied as a function of the solution …

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Pltl Impacts A Career – From Peer Leader To The Professoriate, Jason Gillmore Oct 2010

Pltl Impacts A Career – From Peer Leader To The Professoriate, Jason Gillmore

Faculty Publications

No abstract provided.

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Guest Induced Transformations Of Assembled Pyridyl Bis-Urea Macrocycles, Kinkini Roy, Chun Wang, Mark D. Smith, Mahender B. Dewal, Arief C. Wibowo, Julius C. Brown, Shugo Ma, Linda S. Shimizu Aug 2010

Guest Induced Transformations Of Assembled Pyridyl Bis-Urea Macrocycles, Kinkini Roy, Chun Wang, Mark D. Smith, Mahender B. Dewal, Arief C. Wibowo, Julius C. Brown, Shugo Ma, Linda S. Shimizu

Faculty Publications

Pyridine macrocycles with no cavities assembled into close packed columns yet absorbed guests including hydrogen, carbon dioxide, and iodine.

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Fluorescent Chemosensors For Toxic Organophosphorus Pesticides: A Review, Sherine O. Obare, Chandrima De, Wen Guo, Tajay L. Haywood, Tova A. Samuels, Clara P. Adams, Noah O. Masika, Desmond H. Murray, Ginger A. Anderson, Keith Campbell, Kenneth Fletcher Jul 2010

Fluorescent Chemosensors For Toxic Organophosphorus Pesticides: A Review, Sherine O. Obare, Chandrima De, Wen Guo, Tajay L. Haywood, Tova A. Samuels, Clara P. Adams, Noah O. Masika, Desmond H. Murray, Ginger A. Anderson, Keith Campbell, Kenneth Fletcher

Faculty Publications

Many organophosphorus (OP) based compounds are highly toxic and powerful inhibitors of cholinesterases that generate serious environmental and human health concerns. Organothiophosphates with a thiophosphoryl (P=S) functional group constitute a broad class of these widely used pesticides. They are related to the more reactive phosphoryl (P=O) organophosphates, which include very lethal nerve agents and chemical warfare agents, such as, VX, Soman and Sarin. Unfortunately, widespread and frequent commercial use of OP-based compounds in agricultural lands has resulted in their presence as residues in crops, livestock, and poultry products and also led to their migration into aquifers. Thus, the design of …

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Tobacco Mosaic Virus Based Thin Film Sensor For Detection Of Volatile Organic Compounds, Michael A. Bruckman, Jie Liu, Goutam Koley, Yu Li, Brian C. Benicewicz, Zhongwei Niu, Qian Wang Jun 2010

Tobacco Mosaic Virus Based Thin Film Sensor For Detection Of Volatile Organic Compounds, Michael A. Bruckman, Jie Liu, Goutam Koley, Yu Li, Brian C. Benicewicz, Zhongwei Niu, Qian Wang

Faculty Publications

A thin film sensor for the detection of volatile organic compounds (VOC) was fabricated by deposition of oligo-aniline grafted tobacco mosaic virus (TMV) onto a glass substrate. The oligo-aniline motifs were conjugated onto the TMV surface by a traditional diazonium coupling reaction to tyrosine residues followed by Cu(I) catalyzed alkyne-azide cycloaddition (CuAAC) reaction. The modified TMV was easily fabricated into a thin film by directly drop coating onto a glass substrate. Upon integration of the glass substrate into a prototypical device, the virus-based thin film exhibited good sensitivity and selectivity toward ethanol and methanol vapour.

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Crossed-Beams And Theoretical Studies Of Hyperthermal Reactions Of O(3P) With Hcl†, Jianming Zhang, Amy L. Brunsvold, Hari P. Upadhyaya, Timothy K. Minton, Jon P. Camden, Sophya V. Garashchuk, George C. Schatz Mar 2010

Crossed-Beams And Theoretical Studies Of Hyperthermal Reactions Of O(3P) With Hcl†, Jianming Zhang, Amy L. Brunsvold, Hari P. Upadhyaya, Timothy K. Minton, Jon P. Camden, Sophya V. Garashchuk, George C. Schatz

Faculty Publications

The reaction of O(3 P) with HCl at hyperthermal collision energies (45-116 kcal mol-1 ) has been investigated with crossed-molecular beams experiments and direct dynamics quasi-classical trajectory calculations. The reaction may proceed by two primary pathways, (1) H-atom abstraction to produce OH and Cl and (2) H-atom elimination to produce H and ClO. The H-atom abstraction reaction follows a stripping mechanism, in which the reagent O atom approaches the HCl molecule at large impact parameters and the OH product is scattered in the forward direction, defined as the initial direction of the reagent O atoms. The H-atom elimination reaction is …

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An Electrochemical Cell For The Efficient Turn Around Of Wafer Working Electrodes, Nicholas Wozniak, Alyssa Frey, Lucas Osterbur, Timothy Boman, Jennifer R. Hampton Mar 2010

An Electrochemical Cell For The Efficient Turn Around Of Wafer Working Electrodes, Nicholas Wozniak, Alyssa Frey, Lucas Osterbur, Timothy Boman, Jennifer R. Hampton

Faculty Publications

We present a new design for an electrochemical cell for use with wafer working electrodes. The key feature of the design is the use of half turn thumb screws to form a liquid-tight seal between an o-ring and the sample surface. The assembly or disassembly of the cell requires a half turn of each thumb screw, which facilitates the quick turn around of wafer samples. The electrochemical performance of the cell is demonstrated by cyclic voltammetry and double step chronoamperometry measurements of the ferricyanide/ferrocyanide couple.

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Organization, Structure, And Assembly Of Alpha-Carboxysomes Determined By Electron Cryotomography Of Intact Cells, Cristina V. Iancu, Dylan M. Morris, Zhicheng Dou, Sabine Heinhorst, Gordon C. Cannon, Grant J. Jensen Feb 2010

Organization, Structure, And Assembly Of Alpha-Carboxysomes Determined By Electron Cryotomography Of Intact Cells, Cristina V. Iancu, Dylan M. Morris, Zhicheng Dou, Sabine Heinhorst, Gordon C. Cannon, Grant J. Jensen

Faculty Publications

Carboxysomes are polyhedral inclusion bodies that play a key role in autotrophic metabolism in many bacteria. Using electron cryotomography, we examined carboxysomes in their native states within intact cells of three chemolithoautotrophic bacteria. We found that carboxysomes generally cluster into distinct groups within the cytoplasm, often in the immediate vicinity of polyphosphate granules, and a regular lattice of density frequently connects granules to nearby carboxysomes. Small granular bodies were also seen within carboxysomes. These observations suggest a functional relationship between carboxysomes and polyphosphate granules. Carboxysomes exhibited greater size, shape, and compositional variability in cells than in purified preparations. Finally, we …

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Tetraaquabis(3-Fluoropyridine-4-Carboxylato-Κn)Zinc(Ii) Dihydrate, Jonetha Fleming, Jennifer Kelley, Leroy Peterson Jr., Mark D. Smith, Hans-Conrad Zur Loye Feb 2010

Tetraaquabis(3-Fluoropyridine-4-Carboxylato-Κn)Zinc(Ii) Dihydrate, Jonetha Fleming, Jennifer Kelley, Leroy Peterson Jr., Mark D. Smith, Hans-Conrad Zur Loye

Faculty Publications

In the title compound, [Zn(C6H3FNO2)2(H2O)4]·2H2O, the ZnII atom is octahedrally coordinated in a ZnO4N2 environment by two 3-fluoropyridine-4-carboxylate (3-fpy4-cbx) ligands and four water molecules. The [Zn(3-fpy4-cbx)2(H2O)4] molecules form a three-dimensional network through strong O-HO and weak O-HF hydrogen bonds between 3-fpy4-cbx and water molecules. The crystal used for data collection was a twin, with the twin law corresponding to a 180° rotation about the real-space [001] axis. The major twin fraction refined to 0.795 (1).

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Carboxysomal Carbonic Anhydrases: Structure And Role In Microbial Co2 Fixation, Gordon C. Cannon, Sabine Heinhorst, Cheryl A. Kerfeld Feb 2010

Carboxysomal Carbonic Anhydrases: Structure And Role In Microbial Co2 Fixation, Gordon C. Cannon, Sabine Heinhorst, Cheryl A. Kerfeld

Faculty Publications

Cyanobacteria and some chemoautotrophic bacteria are able to grow in environments with limiting CO2 concentrations by employing a CO2-concentrating mechanism (CCM) that allows them to accumulate inorganic carbon in their cytoplasm to concentrations several orders of magnitude higher than that on the outside. The final step of this process takes place in polyhedral protein microcompartments known as carboxysomes, which contain the majority of the CO2-fixing enzyme, RubisCO. The efficiency of CO2 fixation by the sequestered RubisCO is enhanced by co-localization with a specialized carbonic anhydrase that catalyzes dehydration of the …

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Effects Of Metal Compounds With Distinct Physicochemical Properties On Iron Homeostasis And Antibacterial Activity In The Lungs: Chromium And Vanadium, Mitchell D. Cohen, Maureen Sisco, Colleen Prophete, Kotaro Yoshida, Lung-Chi Chen, Judith T. Zelikoff, Jason Smee, Alvin A. Holder, Jacqueline Stormhuerner, Debbie C. Crans, Andrew J. Ghio Feb 2010

Effects Of Metal Compounds With Distinct Physicochemical Properties On Iron Homeostasis And Antibacterial Activity In The Lungs: Chromium And Vanadium, Mitchell D. Cohen, Maureen Sisco, Colleen Prophete, Kotaro Yoshida, Lung-Chi Chen, Judith T. Zelikoff, Jason Smee, Alvin A. Holder, Jacqueline Stormhuerner, Debbie C. Crans, Andrew J. Ghio

Faculty Publications

In situ reactions of metal ions or their compounds are important mechanisms by which particles alter lung immune responses. The authors hypothesized that major determinants of the immunomodulatory effect of any metal include its redox behavior/properties, oxidation state, and/or solubility, and that the toxicities arising from differences in physicochemical parameters are manifest, in part, via differential shifts in lung iron (Fe) homeostasis. To test the hypotheses, immunomodulatory potentials for both pentavalent vanadium (V(V); as soluble metavanadate or insoluble vanadium pentoxide) and hexavalent chromium (Cr(VI); as soluble sodium chromate or insoluble calcium chromate) were quantified in rats after inhalation (5 h/day …

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Poly[[(Μ-2,2'-Bipyrimidine-Κ4N1,N1':N3,N3')(Μ-Sulfato-Κ2O:O')Zinc(Ii)] Monohydrate], Aaron Oxendine, Jennifer Kelley, Leroy Peterson Jr., Mark D. Smith, Hans-Conrad Zur Loye Jan 2010

Poly[[(Μ-2,2'-Bipyrimidine-Κ4N1,N1':N3,N3')(Μ-Sulfato-Κ2O:O')Zinc(Ii)] Monohydrate], Aaron Oxendine, Jennifer Kelley, Leroy Peterson Jr., Mark D. Smith, Hans-Conrad Zur Loye

Faculty Publications

In the title compound, {[Zn(SO4)(C8H6N4)]·H2O}n, the ZnII atom is in a distorted octahedral environment. The ZnII atoms are bridged by both 2,2'-bipyrimidine and sulfate ligands, thus forming a three-dimensional polymeric metal-organic solid that contains uncoordinated water molecules in the interstitial space. O-HO hydrogen bonding consolidates the crystal structure.

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A Dielectric Affinity Microbiosensor, Xian Huang, Siqi Li, Jerome S. Schultz, Qian Wang, Qiao Lin Jan 2010

A Dielectric Affinity Microbiosensor, Xian Huang, Siqi Li, Jerome S. Schultz, Qian Wang, Qiao Lin

Faculty Publications

We present an affinity biosensing approach that exploits changes in dielectric properties of a polymer due to its specific, reversible binding with an analyte. The approach is demonstrated using a microsensor comprising a pair of thin-film capacitive electrodes sandwiching a solution of poly(acrylamide-ran-3-acrylamidophenylboronic acid), a synthetic polymer with specific affinity to glucose. Binding with glucose induces changes in the permittivity of the polymer, which can be measured capacitively for specific glucose detection, as confirmed by experimental results at physiologically relevant concentrations. The dielectric affinity biosensing approach holds the potential for practical applications such as long-term continuous glucose monitoring.

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Construction, Figures Of Merit And Testing Of A Single-Cell Fluorescence Excitation Spectroscopy System, Laura S. Hill, Tammi L. Richardson, Louisa T.M. Profeta, Timothy J. Shaw, Christopher J. Hintz, Benjamin S. Twining, Evelyn Lawrenz, Micheal L. Myrick Jan 2010

Construction, Figures Of Merit And Testing Of A Single-Cell Fluorescence Excitation Spectroscopy System, Laura S. Hill, Tammi L. Richardson, Louisa T.M. Profeta, Timothy J. Shaw, Christopher J. Hintz, Benjamin S. Twining, Evelyn Lawrenz, Micheal L. Myrick

Faculty Publications

Characterization of phytoplankton community composition is critical to understanding the ecology and biogeochemistry of the oceans. One approach to taxonomic characterization takes advantage of differing pigmentation between algal taxa and thus differences in fluorescence excitation spectra. Analyses of bulk water samples, however, may be confounded by interference from chromophoric dissolved organic matter or suspended particulate matter. Here, we describe an instrument that uses a laser trap based on a Nikon TE2000-U microscope to position individual phytoplankton cells for confocal fluorescence excitation spectroscopy, thus avoiding interference from the surrounding medium. Quantitative measurements of optical power give data in the form of …

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Quantum Trajectory Dynamics In Imaginary Time With The Momentum-Dependent Quantum Potential, Sophya Garashchuk Jan 2010

Quantum Trajectory Dynamics In Imaginary Time With The Momentum-Dependent Quantum Potential, Sophya Garashchuk

Faculty Publications

The quantum trajectory dynamics is extended to the wave function evolution in imaginary time. For a nodeless wave function a simple exponential form leads to the classical-like equations of motion of trajectories, representing the wave function, in the presence of the momentum-dependent quantum potential in addition to the external potential. For a Gaussian wave function this quantum potential is a time-dependent constant, generating zero quantum force yet contributing to the total energy. For anharmonic potentials the momentum-dependent quantum potential is cheaply estimated from the global Least-squares Fit to the trajectory momenta in the Taylor basis. Wave functions with nodes are …

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Platinum And Palladium Complexes Containing Cationic Ligands As Catalysts For Arene Hid Exchange And Oxidation., J. Brannon Gary Jan 2010

Platinum And Palladium Complexes Containing Cationic Ligands As Catalysts For Arene Hid Exchange And Oxidation., J. Brannon Gary

Faculty Publications

The direct functionalization of CH bonds has frequently been deemed a “Holy Grail” of organometallic chemistry.[1] A seminal example of this transformation was the demonstration by Shilov and co-workers that platinum(II) salts catalyze the direct oxidation of alkanes into their corresponding alcohols and alkyl halides.[2] Subsequent work in this area has focused on surveying diverse ligands for these reactions in an effort to enhance reactivity and selectivity, slow catalyst decomposition, and replace platinum(IV)-based oxidants with more cost-effective alternatives.[3–5] In a key development, chemists at Catalytica identified [bpymPtCl2] (bpym = bipyrimidine) as a pre-catalyst for the oxidation of CH4 into CH3OSO3H …

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Mechanistic And Computational Studies Of Oxidatively-Induced Aryl-Cf3 Bond Formation At Palladium, J. Brannon Gary Jan 2010

Mechanistic And Computational Studies Of Oxidatively-Induced Aryl-Cf3 Bond Formation At Palladium, J. Brannon Gary

Faculty Publications

This article describes the rational design of 1st generation systems for oxidatively-induced Aryl– CF3 bond-forming reductive elimination from PdII. Treatment of (dtbpy)PdII(Aryl)(CF3) (dtbpy = di-tert-butylbipyridine) with NFTPT (N-fluoro-1,3,5-trimethylpyridium triflate) afforded the isolable PdIV intermediate (dtbpy)PdIV(Aryl)(CF3)(F)(OTf). Thermolysis of this complex at 80 °C resulted in Aryl–CF3 bond-formation. Detailed experimental and computational mechanistic studies have been conducted to gain insights into the key reductive elimination step. Reductive elimination from this PdIV species proceeds via pre-equilibrium dissociation of TfO− followed by Aryl–CF3 coupling. DFT calculations reveal that the transition state for Aryl–CF3 bond formation involves the CF3 acting as an electrophile with the …

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Transition-Metal Ion Exchange Using Poly(Ethylene Glycol) Oligomers As Solvents, Gina M. Canfield, Michael Bizimis, Susan E. Latturner Jan 2010

Transition-Metal Ion Exchange Using Poly(Ethylene Glycol) Oligomers As Solvents, Gina M. Canfield, Michael Bizimis, Susan E. Latturner

Faculty Publications

Poly(ethylene glycol) oligomers have been found to be effective as alternative solvents for the ion exchange of Mn2þ , Fe2 þ , and Co2þ into hydrated and dehydrated Zeolite X (Na80Al80Si112- O384 3 nH2O). When attempted in aqueous solutions, the exchange of these cations quickly leads to destruction of the zeolite structure within 1-2 exchange cycles. However, in PEG oligomer solvents, the structure can be maintained and exchanges of 48% (Co2þ ), 80% (Mn2þ ), and 91% (Fe2þ ) are observed after one cycle under hydrated conditions. When rigorous steps are taken to remove all water from the zeolite before …

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Dynamic Path Bifurcation For The Beckmann Reaction: Observation And Implication, H. Yamataka, M. Sato, H. Hasegawa, Salai Cheettu Ammal Jan 2010

Dynamic Path Bifurcation For The Beckmann Reaction: Observation And Implication, H. Yamataka, M. Sato, H. Hasegawa, Salai Cheettu Ammal

Faculty Publications

The reaction of oximes to amides, known as the Beckmann rearrangement, may undergo fragmentation to form carbocations + nitriles instead of amides when the cations have reasonable stability. The reactions of oxime derivatives of 1-substituted-phenyl-2-propanones and 3-substituted-phenyl-2-butanones in aqueous solvents gave both rearrangement and fragmentation products, the ratio of which was dependent on substituents. Transition state (TS) optimizations and intrinsic reaction coordinate (IRC) calculations for the reaction of 1-phenyl-2-propanone oximes showed that there is a single TS for each substituted compound. The IRC path from the TS either led to a rearrangement product or a fragmentation product depending on the …

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