Chemistry Commons^™

Determination Of Copper In Aqueous Solutions By Chelation With Diethyldithiocarbamate, Caitlin Allison

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

"At The Critical Point Of A Solution, Changes In The Reaction Rate Of A Reaction Can Occur...", Clayton Craft

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

Effects Of Ions On The Activity Of Peptidyl-Trna Hydrolase, Blake Holloway

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

Measuring Antioxidant Properties Through Frap, Xanthine Oxidase, And Orac Assays, Christina Lee

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

Analysis Of Critical Point Phenomena In Binary Liquid Systems, Carl Pattison

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

Microscopic And Spectroscopic Analysis Of Wo3 And Ti-Doped Wo3 Thin Films, Young Taek Yun

Open Access Theses & Dissertations

Tungsten oxide (WO3) has been a subject of high interest for its unique properties, and recently for its importance in different types of industrial applications which ranges from non-emissive displays, optical, microelectronic, catalytic/photocatalytic, humidity, temperature, gas, and biosensor devices. In this study, WO3 and Ti doped thin films were prepared using radio frequency magnetron reactive sputtering at different substrate temperatures ranging from room temperature to 500 ºC in increments of 100 ºC. After forming a hypothesis based on knowledge of established WO3 properties, we attempt in this work to investigate how the doping influences the roughness and the mean grain …

Process-Evaluation Of Tropospheric Humidity Simulated By General Circulation Models Using Water Vapor Isotopic Observations: 2. Using Isotopic Diagnostics To Understand The Mid And Upper Tropospheric Moist Bias In The Tropics And Subtropics, Camille Risi, David Noone, John Worden, Christian Frankenberg, Gabriele Stiller, Michael Kiefer, Bernd Funke, Kaley Walker, Peter Bernath, Matthias Schneider, Sandrine Bony, Jeonghoon Lee, Derek Brown, Christophe Sturm

Chemistry & Biochemistry Faculty Publications

Evaluating the representation of processes controlling tropical and subtropical tropospheric relative humidity (RH) in atmospheric general circulation models (GCMs) is crucial to assess the credibility of predicted climate changes. GCMs have long exhibited a moist bias in the tropical and subtropical mid and upper troposphere, which could be due to the mis-representation of cloud processes or of the large-scale circulation, or to excessive diffusion during water vapor transport. The goal of this study is to use observations of the water vapor isotopic ratio to understand the cause of this bias. We compare the three-dimensional distribution of the water vapor isotopic …

Tunable Gold Nanostructures With Nanocapsules As Template Reaction Vessels, Balasubramanian Ramjee, Srujana Prayakarao, Sangbum Han, Wei Cao

Chemistry & Biochemistry Faculty Publications

Hollow, polymeric, thiol-ene resorcinarene nanocapsules can act as template reaction vessels for the synthesis of gold nanoshells or spherical aggregates of gold nanoparticles depending on the reaction conditions. The spherical nanoparticle aggregates were evaluated as catalysts in the biphasic reduction of 4-nitrophenol.

Biochemical Actions Of A Novel Cis-Terpenone, Lin Zhang

Theses and Dissertations

Abstract BIOCHEMICAL ACTIONS OF A NOVEL CIS-TERPENONE By Lin Zhang, Ph.D. A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University. Virginia Commonwealth University, 2012 Director: Qibing Zhou, Ph.D Assistant Professor Department of Chemistry

Quinone methides are reactive species due to their electrophilicity, and natural quinone methide analogs have broad biological activities. Based on known actions of cytochrome P450 enzymes, we hypothesized that trans-terpenones can be metabolized in cells to form a cascade of metabolite products, which may be biologically active due to the generation of quinine and quinone methide …

Friedel-Crafts Acylation Studies On 3-Alkyl-1-(Phenylsulfonyl)Indoles Using Aluminum Chloride And Bismuth Triflate, Venkateswara Reddy Karrepu

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Using the traditional catalyst, aluminum chloride in stoichiometric amounts, 3-alkyl-1-(phenylsulfonyl)indoles can be regioselectively acylated under Friedel-Crafts conditions at the C-6 position along with 10% of a minor isomer at the C-5 position. Alternatively, using catalytic amounts of the green catalyst, bismuth triflate, C-2 acylation was observed. Therefore, regioselectivity can be controlled by the nature of the Lewis acid catalyst. Moreover, this is the first-time that Friedel-Crafts acylation studies were demonstrated upon 3-alkyl-1-(phenylsulfonyl)indoles.

The Synthesis Of Room-Temperature Ionic Liquids And Their Metathesis Reactions With Dilithium Phthalocyanine, Andrew Michael Beauchamp

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A series of alkoxyalkylammonium salts has been synthesized for use in metathesis reactions with dilithium phthalocyanine. The salts, which were ionic liquids at or near room temperature, were synthesized by a nucleophilic substitution of tris[2-(2-methoxyethoxy)ethyl]amine and iodomethane, iodoethane, bromoethane, 1-bromo-propane, 1-bromo-2-(2-methoxyethoxy)ethane, and [2-[2-(2-methoxyethoxy)ethoxy]-ethoxy] p-toluenesulfonate in yields ranging from 67% - 88%. The methyl, ethyl, propyl and tetra[2-(2-methoxyethoxy)ethyl]ammonium salts were obtained for use in metathesis reactions. The salts were liquid at room temperature, with the exception of tetra[2-(2-methoxyethoxy)ethyl]ammonium bromide which was found to melt at 46° and were thermally stable to approximately 200°. The four salts were used in metathesis reactions …

Facile Synthesis Of Functionalized Poly (Arylene Ether Sulfone)S, Mehmet Tatli

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The synthesis of poly(arylene ether sulfone)s, with a pendant aryl iodide, was achieved via nucleophilic aromatic substitution (NAS) polycondensation of 3-iodo-3',5'-difluoro-diphenylsulfone (2) with Bisphenol-A. Monomer 2 was prepared by the reaction of 3, 5-difluorodiphenylsulfone with N-iodosuccinimide (NIS). Model reactions indicated that the iodo group was stable to NAS conditions. Both GC/MS analysis and NMR spectroscopy indicated quantitative displacement of the two fluorine atoms while the iodo group remained untouched. Furthermore, the modification of the iodo polymer was achieved via Suzuki-Miyaura cross-coupling reaction with phenyl, naphthyl, and phenylacetyl boronic acids. The thermal properties of the polymers were evaluated via DSC and …

Poly(Arylene) Ethers Prepared From Functionalized 3,5-Difluorotriphenylphosphine Oxide, Courtney M. Sutherland

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The di-iodinated derivative of 3,5-difluorotriphenyl phosphine oxide, 3,5-DiFTPO-I2, was synthesized for the modification of poly(arylene ether phosphine oxide)s, PAEPOs. The di-iodinated monomer was polymerized to afford the di-iodinated polymer, a pre-cursor for tailoring solubility and the thermal properties of the PAEPO derivatives via functionalization. The di-iodinated polymer was post-functionalized via the Suzuki Miyaura cross coupling reaction with a variety of boronic acids. The successful conversion of the iodo groups, along with the immense number of possible functional groups that can be introduced to the di-iodinated polymer makes PAEPO-derivative a highly useful thermoplastic with a wide range of potential uses.

The …

Computational Investigations Of The Adsorption Of Molecular Hydrogen On Graphene-Based Nanopore Model, Jared Duncan

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Computational modeling using classical grand canonical Monte Carlo simulations and first-principles calculations were carried out to study the adsorption of molecular hydrogen on nanoporous carbon modeled by the slit- pore geometry. It has previously been shown that hydrogen adsorption on pristine porous carbon has dependence on pore size and that an optimum pore size, which exhibits the maximum mass uptake, exists. There have been suggestions that doping graphitic nanocarbon structures with Pd enhances their adsorption capacity. The pore-size dependence of this change in adsorption brought about by Pd and the conditions at which improvement in adsorption can occur have not …

Synthesis Of Mixed Metal Trinuclear Cluster Of Molybdenum And Tungsten And Their Electrochemistry In Ionic Liquids, Jessica Ann Davis

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Research is being done to find a material to improve the efficiency of the ethanol fuel cell by using a platinum free catalyst. Mo2WO2(O2CCH3)6 cluster was synthesized using Mo2(O2CCH3)4 dimer and Na2WO4. One ionic liquid, EMImBF4, was synthesized using methylimidazolim and chloroethane in the first step, and EMImCl and NaBF4 in the second step. The electrochemical properties of the ionic liquid and the metal cluster were studied. A potential window for the EMImBF4 was found to be 3.2 V. The ionic liquid has a wider potential window, and allowed for the observation of the redox properties of Mo2WO2(O2CCH3)6. The electrochemistry …

A Sers And Sem-Edx Study Of The Antiviral Mechanism Of Creighton Silver Nanoparticles Against Vaccinia Virus, Catherine Binns Anders

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Silver nanoparticles (AgNPs) are well-recognized as antiviral agents but little is known about their mechanism of action. In this study, it was hypothesized that unfunctionalized, Creighton AgNPs of an average diameter of 11 nm will form covalent bonds with vaccinia virus (VV) mainly through the external, entry fusion complex (EFC) proteins. The EFC is housed on the external membrane of VV and contains 9-12 proteins having numerous cysteine groups, intramolecular disulfide bonds, aromatic moieties and myristic acids bound to the N-terminus of glycine residues. VV (1012 PFUs) was incubated at 37oC for one hour with Creighton AgNPs that were size …

Cathodic Deposition Of Triangular Tungsten Clusters From Ionic Liquids: An Explorative Study, Linda N. Ubadigbo

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In the present work, the triangular tungsten clusters {[W3O2(O2CCH3)6](H2O)3}(CF3SO3)2 and {[W3O2(O2CCH2CH3)6](H2O)3}(BF4)2. 5.5H2O were dissolved in both hydrophobic and hydrophilic ionic liquids (ILs) and subjected to a cathodic potential of roughly 2V. It was proposed that successful deposition of these metal clusters on a platinum electrode would yield Pt-supported anodic catalysts which could be used in ethanol fuel cells (EFCs). Visual examination of the electrode surfaces indicated that a film had been deposited, however, the surface with W3(CF3SO3)2 quickly oxidized when removed from the IL. Therefore, SEM imaging and EDX analysis of the W3(BF4)2 surface were performed. The data indicated that …

Development Of Tailor-Designed Gold-Platinum Nanoparticles Binary Catalysts For Efficient Formic Acid Electrooxidation, Islam M. Al-Akraa Dr, Ahmad M. Mohammad Prof, Mohamed S. El-Deab Prof, Bahgat E. El-Anadouli Prof

Chemical Engineering

The modification of a glassy carbon (GC) electrode with platinum (PtNPs) and gold (AuNPs) nanoparticles is targeted to fabricate efficient anodes for the electrooxidation of formic acid (FA). A proper adjustment of the deposition sequence of PtNPs and AuNPs could eventually enhance the electrocatalytic activity of the electrode in such a way that suppresses the CO poisoning effect during FA oxidation. The highest catalytic activity is obtained at the Au/Pt/GC electrode (with PtNPs firstly deposited on the GC electrode followed by AuNPs). This superb enhancement is quantified by comparing the relative ratio of the direct vs. the indirect oxidation peaks …

Self-Assembling Subnanometer Pores With Unusual Mass-Transport Properties, Xibin Zhou, Guande Liu, Kazuhiro Yamato, Yi Shen, Ruixian Cheng, Xiaoxi Wei, Wanli Bai, Yi Gao, Hui Li, Yi Liu, Futao Liu, Daniel M. Czajkowsky, Jingfang Wang, Michael J. Dabney, Zhonghou Cai, Jun Hu, Frank V. Bright, Lan He, Xiao Cheng Zeng, Zhifeng Shao, Bing Gong

Xiao Cheng Zeng Publications

A long-standing aim in molecular self-assembly is the development of synthetic nanopores capable of mimicking the mass-transport characteristics of biological channels and pores. Here we report a strategy for enforcing the nanotubular assembly of rigid macrocycles in both the solid state and solution based on the interplay of multiple hydrogen-bonding and aromatic π − π stacking interactions. The resultant nanotubes have modifiable surfaces and inner pores of a uniform diameter defined by the constituent macrocycles. The self-assembling hydrophobic nanopores can mediate not only highly selective transmembrane ion transport, unprecedented for a synthetic nanopore, but also highly efficient transmembrane water permeability. …

Ccpa Regulates Arginine Biosynthesis In Staphylococcus Aureus Through Repression Of Proline Catabolism, Austin S. Nuxoll, Steven M. Halouska, Marat R. Sadykov, Mark L. Hanke, Kenneth W. Bayles, Tammy Kielian, Robert Powers, Paul D. Fey

Department of Chemistry: Faculty Publications

Staphylococcus aureus is a leading cause of community-associated and nosocomial infections. Imperative to the success of S. aureus is the ability to adapt and utilize nutrients that are readily available. Genomic sequencing suggests that S. aureus has the genes required for synthesis of all twenty amino acids. However, in vitro experimentation demonstrates that staphylococci have multiple amino acid auxotrophies, including arginine. Although S. aureus possesses the highly conserved anabolic pathway that synthesizes arginine via glutamate, we demonstrate here that inactivation of ccpA facilitates the synthesis of arginine via the urea cycle utilizing proline as a substrate. Mutations within putA, rocD, …

Unraveling The Structural Complexity In A Single-Stranded Rna Tail: Implications For Efficient Ligand Binding In The Prequeuosine Riboswitch, Catherine D. Eichhorn, Jun Feng, Krishna C. Suddala, Nils G. Walter, Charles L. Brooks Iii, Hashim M. Al-Hashimi

Department of Chemistry: Faculty Publications

Single-stranded RNAs (ssRNAs) are ubiquitous RNA elements that serve diverse functional roles. Much of our understanding of ssRNA conformational behavior is limited to structures in which ssRNA directly engages in tertiary interactions or is recognized by proteins. Little is known about the structural and dynamic behavior of free ssRNAs at atomic resolution. Here, we report the collaborative application of nuclear magnetic resonance (NMR) and replica exchange molecular dynamics (REMD) simulations to characterize the 12 nt ssRNA tail derived from the prequeuosine riboswitch. NMR carbon spin relaxation data and residual dipolar coupling measurements reveal a flexible yet stacked core adopting an …

Crystalline Nano Structures, Barry Chin Li Cheung, Joseph Reese Brewer, Nirmalendu Deo

Department of Chemistry: Faculty Publications

The present invention comprises nano obelisks and nanostructures and methods and processes for same. The nano obelisks of the present invention are advantageous structures for use as electron source emitters. For example, the ultra sharp obelisks can be used as an emitter source to generate highly coherent and high energy electrons with high current.

Surfactant-Free Hybridization Of Transition Metal Oxide Nanoparticles With Conductive Graphene For High-Performance Supercapacitor, Wen Qian, Zhiqiang Chen, Steven Cottingham, William Alexander Merrill, Natasja A. Swartz, Andrea Goforth, Tami Lasseter Clare, Jun Jiao

Chemistry Faculty Publications and Presentations

In order to improve specific capacitance and limit electrical resistance, high-quality exfoliatedgraphene decorated with transition metal (Fe, Mn, Co) oxide nanoparticles (NPs) has been successfully synthesized without the use of surfactant via a simple, general, environmentally-friendly chemical process. The specific capacitance of as-prepared graphene/Mn₃O₄ composite reach 239.6 F/g, when employed as the anode material in neutral NaCl electrolyte solutions (cf. 98.2 F/g for pristine graphene and 141.4 F/g for pure Mn₃O₄ NPs), which indicate the synergetic effects from both graphene and attached Mn₃O₄ NPs. Moreover, the high conductivity of …

Diversity Of Archaeosine Synthesis In Crenarchaeota, Gabriela Phillips, Manal A. Swairjo, Kirk W. Gaston, Marc Bailly, Patrick A. Limbach, Dirk Iwata-Reuyl, Valérie De Crécy-Lagard

Chemistry Faculty Publications and Presentations

Archaeosine (G+) is found at position 15 of many archaeal tRNAs. In Euryarchaeota, the G+ precursor, 7-cyano-7-deazaguanine (preQ0), is inserted into tRNA by tRNA-guanine transglycosylase (arcTGT) before conversion into G+ by ARChaeosine Synthase (ArcS). However, many Crenarchaeota known to harbor G+ lack ArcS homologs. Using comparative genomics approaches, two families that could functionally replace ArcS in these organisms were identified: 1) GAT-QueC, a two-domain family with an N-terminal glutamine amidotransferase class-II domain fused to a domain homologous to QueC, the enzyme that produces preQ0; 2) QueF-like, a family homologous to the bacterial enzyme catalyzing the reduction of preQ0 to 7- …

Advanced Nanohybrid Materials: Surface Modification And Applications, Li-Hung Liu, Rémi Métivier, Shanfeng Wang, Hui Wang

Chemistry Faculty Publications and Presentations

The field of functional nanoscale hybrid materials is one of the most promising and rapidly emerging research areas in materials chemistry. Nanoscale hybrid materials can be broadly defined as synthetic materials with organic and inorganic components that are linked together by noncovalent bonds (Class I, linked by hydrogen bond, electrostatic force, or van der Waals force) or covalent bonds (Class II) at nanometer scale. The unlimited possible combinations of the distinct properties of inorganic, organic, or even bioactive components in a single material, either in molecular or nanoscale dimensions, have attracted considerable attention. This approach provides an opportunity to create …

Computational Study Of The Hydration Of Sulfuric Acid Dimers: Implications For Acid Dissociation And Aerosol Formation, Berhane Temelso, Thuong Ngoc Phan, George C. Shields

Faculty Journal Articles

We have investigated the thermodynamics of sulfuric acid dimer hydration using ab initio quantum mechanical methods. For (H₂SO₄)₂(H₂O)_n where n = 0−6, we employed high-level ab initio calculations to locate the most stable minima for each cluster size. The results presented herein yield a detailed understanding of the first deprotonation of sulfuric acid as a function of temperature for a system consisting of two sulfuric acid molecules and up to six waters. At 0 K, a cluster of two sulfuric acid molecules and one water remains undissociated. Addition of a second …

5a-Butyl-1,3,8,10-Tetra-Chloro-7,13-Bis-(4-Nitro-Benzo-Yl)-5a,6a,12a,12b-Tetra-Hydro-7h,13h-Thieno[2,3-B:4,5-B']Bis-(1,4-Benzoxazine), Kai Tang, Margaret E. Kastner

Faculty Journal Articles

The title compound, C(34)H(24)Cl(4)N(4)O(8)S, is a linear penta-cyclic system formed of two substituted benzoxazinyl groups fused to 2-n-butyl-tetra-hydro-thio-phene. The oxazine ring, which is fused to the n-butyl-substituted side of the thio-phene ring, is in a boat conformation. The other fused oxazine ring and the tetra-hydro-thiene ring are each in an envelope conformation. The bridgehead C atom alpha to both the S and N atoms forms the flap of each envelope. This results in a twist of the penta-cyclic system such that the dihedral angle between the terminal dichloro-benzene rings is 82.92 (8)°. In the crystal, inversion-related mol-ecules form a weakly …

Identification Of The Biogenic Compounds Responsible For Size-Dependent Nanoparticle Growth, Paul M. Winkler, John Ortega, Thomas Karl, Luca Cappellin, Hans R. Friedli, Kelley Barsanti, Peter H. Mcmurry, James N. Smith

Civil and Environmental Engineering Faculty Publications and Presentations

The probability that freshly nucleated nanoparticles can survive to become cloud condensation nuclei is highly sensitive to particle growth rates. Much of the growth of newly formed ambient nanoparticles can be attributed to oxidized organic vapors originating from biogenic precursor gases. In this study we investigated the chemical composition of size-selected biogenic nanoparticles in the size range from 10 to 40 nm. Particles were formed in a flow tube reactor by ozonolysis ofα-pinene and analyzed with a Thermal Desorption Chemical Ionization Mass Spectrometer. While we found similar composition in 10 and 20 nm particles, the relative amounts of …

Investigations Into The Role Of Natural Organic Matter As An Interface Between Aquatic Organisms And Environmental Pollutants, Caroline Lillian Schneider

LSU Doctoral Dissertations

The impact of the continuous pollution of freshwater environments by multiple pollutants has not been well-studied. The goal of this research was to evaluate the toxicity of several modern pollutants in a model environment. The prokaryotic, unicellular blue-green algae Synechocystis WT6803 and the eukaryotic, multicellular Utterbackia imbecillis mussel larvae were studied along with Suwannee River natural organic matter (NOM). The toxicity response of the blue-green algae Synechocystis sp. was measured through changes in growth rates. The inorganic pollutant silver nanoparticles (0.044 μM) were toxic. Gold nanoparticles did not affect the growth rate. The addition of 15 mg/L NOM partially inhibited …

The First Example Of Amine-Induced Reversal Of Diastereoselectivity In Acylation Of Some Trans-2-Substituted Cyclohexanols, Andrey V. Samoshin, Jasper Visser, Matthew Curtis, Vyacheslav V. Samoshin, Andreas H. Franz

College of the Pacific Faculty Articles

The reaction between racemic acyl chlorides and racemic trans-2-substituted-cyclohexanols proceeds diastereoselectively. We found for the first time that addition of a tertiary amine not only accelerates the acylation, but for some substituents leads to complete inversion of diastereoselectivity. These observations have been rationalized in terms of a possible stereoselective intramolecular assistance by the substituent group during the acylation of the neighboring hydroxyl group.