Chemistry Commons^™

Identification Of The Domains Of Urer, An Arac-Like Transcriptional Regulator Of The Urease Gene Cluster In Proteus Mirabilis, Carrie A. Poore, Christopher Coker, Jonathan D. Dattelbaum, Harry L.T. Mobley

Chemistry Faculty Publications

Proteus mirabilis urease catalyzes the hydrolysis of urea to CO₂ and NH₃, resulting in urinary stone formation in individuals with complicated urinary tract infections. UreR, a member of the AraC family, activates transcription of the genes encoding urease enzyme subunits and accessory proteins, ureDABCEFG, as well as its own transcription in the presence of urea. Based on sequence homology with AraC, we hypothesized that UreR contains both a dimerization domain and a DNA-binding domain. A translational fusion of the leucine zipper dimerization domain (amino acids 302 to 350) of C/EBP and the C-terminal half of UreR …

Linkage Isomers Of Tungsten Carbonyl Complexes Of Ph₂Pch₂Pphch₂Pph₂, Chaminda P. Gamage

Masters Theses

The linkage isomers (CO)₅W[η¹-PPh₂CH₂PPhCH₂PPh₂], 1, and (CO)₅ W[η¹-PPh(CH₂PPh₂)₂], 2, have been synthesized from the reaction of (OC)₅W(NH₂Ph) and Ph₂PCH₂PPhCH₂PPh₂. In addition, linkage isomers (CO)₅W[μ-PPh₂CH₂PPhCH₂PPh₂]-W(CO)₅, 3, and (CO)₅W{μ-PPh₂CH₂PPh[W(CO)₅] CH₂PPh₂}, 4, have been prepared. Attempts to obtain (OC)₅WPPh₂CH …

Probing The Capabilities Of Copper Complexes With Nitrogen And Sulfur Containing Macrocyclic Ligands As Aziridination Catalysts, Jonathan Natkin

Honors Theses

Aziridines are three-membered rings containing one nitrogen atom. They are useful as synthetic intermediates in many organic reactions. Much work has been devoted to synthesizing their analogs, cyclopropanes and epoxides, but little work has been done on the aziridination reaction. This study endeavored to probe the efficiencies of novel copper aziridination catalysts with N3 and S3 macrocyclic ligands compared to an NS2 analog for the reaction with the nitrene precursor (N-(paratosylsulfonyl) imino)phenyliodinane, PhINTs, and the olefin styrene. The nitrogen containing catalyst complex gave higher yields than the sulfur containing catalyst complex. Both ligands were found to decrease the yield of …

A Ring-Closing Strategy For The Synthesis Of Β,Γ-Unsaturated Δ-Lactones, Erbing Hua

Masters Theses

Spiro β,γ-unsaturated δ-lactones and fused β,γ-unsaturated δ-lactones are integral to a large number of naturally occurring compounds exhibiting a diverse range of biological activity. A new synthetic route to β,γ-unsaturated δ-lactones, consisting of a three-step sequence, has been investigated for the synthesis of these kinds of pharmacological intermediates. Ring closure of a β-hydroxy acid by dehydration, providing a 4-vinyl substituted β-lactone, and its ring expansion/rearrangement are the two key steps in this protocol. The results have proved that this new method is efficient and quite expeditious. One spiro and four fused β,γ-unsaturated δ-lactones were synthesized through this protocol albeit in …

The Synthesis Of 2-Indenylphenols: Potential Ligands For Transition Metals, Yoon Jae Kim

Masters Theses

The syntheses of 2-(2-indenyl)-phenol and 2-(1-indenyl)-phenol via a three-step sequence have been developed. In the first steps of the sequence, a Grignard reagent formed from 2-iodoanisole or 2-bromoanisole reacted with 1-indanone or 2-indanone in yields that ranged from 11.3% to 67.2%. The second step consisted of acid-catalyzed dehydration of the alcohol formed in step 1 to make a 2-inenyl anisole; yields in the second step were 45.2% to nearly quantitative. Finally, demethylation of the 2-indenyl anisole was achieved with AlBr₃ in ethanethiol in yields ranging from 52.9% to 0 %. Each product was characterized by ¹H and ^{13 …}

The Synthesis Of Deuterated Arylamine Dna Adducts For Use In The Development Of An Isotope Dilution Lc/Ms/Ms Method, Philip Dmitri Olsen

LSU Doctoral Dissertations

Polycyclic aromatic amines (arylamines) are a class of chemical carcinogens that are prevalent in environmental and industrial settings. In order to study the mechanism of their toxicity a quantitative and qualitative detection method was developed to measure the C8-adenine adducts of benzidine and 2-aminofluorene in DNA samples. To do this a novel synthetic method using a palladium catalyst was developed to prepare authentic and deuterated arylamine adducts to serve as standards. These standards were then used to develop a high performance liquid chromatography, electrospray, tandem mass spectrometry, isotope dilution, detection method. To demonstrate the validity of this method two spike …

Boron-Doped Homoepitaxial Diamond (100) Film Investigated By Scanning Tunneling Microscopy, Bing Xiao, Weihai Fu, Sacharia Albin, Jason Moulton, John Cooper

Electrical & Computer Engineering Faculty Publications

Conducting epitaxial diamond films of high quality are essential for many diamond studies and diamond electronic device fabrication. We have grown boron-doped epitaxial diamond films on type Ila natural diamond (100) substrates by microwave plasma chemical vapor deposition. A gas mixture of H₂/CH₄ was used. Boron doping was done by placing solid sources of pure boron in the microwave plasma. Homoepitaxial films with atomic smoothness were achieved under the following growth conditions: substrate temperature 900 °C, gas pressure 40 Torr, and gas flow rates of H₂/CH₄ = 900/7.2 seem. The growth rate was 0.87 …

Thermal Degradation Of Pvc In The Presence Of Polystyrene, Qiang Yao, Charles A. Wilkie

Chemistry Faculty Research and Publications

The thermal degradation of poly(vinyl chloride) (PVC) and blends of PVC with polystyrene has been studied using thermogravimetric analysis coupled to Fourier transform infrared spectroscopy. The degradation of PVC commences at weak links by an ionic pathway, but there is evidence to suggest the presence of a radical pathway at high temperatures. While there is some chemical interaction between PVC and polystyrene, the principal mode of stabilization is a physical process.

Electron Redistribution Of Aromatic Ligands In (Arene)Cr(Co)3 Complexes. Structural (Bond-Length) Changes As Quantitative Measures, P. Le Maguères, Sergey V. Lindeman, Jay K. Kochi

Chemistry Faculty Research and Publications

Arene ligands experience significant ring expansion upon coordination with chromium tricarbonyl, as established by precise X-ray crystallographic analyses of various (η⁶-arene)Cr(CO)₃ complexes. Such changes in ligand structures result from the charge (electron) redistribution, Ar⁺−Cr^-, upon arene coordination, since they are closely related to those found in the intermolecular 1:1 complexes of the corresponding series of arenes with nitrosonium cation (NO⁺). The latter are prototypical examples of charge-transfer complexes as described by Mulliken. As such, they show enhanced degrees of charge (electron) transfer that approach unity, which is confirmed by quantitative comparison …

Noncovalent Binding Of The Halogens To Aromatic Donors. Discrete Structures Of Labile Br2 Complexes With Benzene And Toluene, Alexandr V. Vasilyev, Sergey V. Lindeman, Jay K. Kochi

Chemistry Faculty Research and Publications

Precise molecular structures resulting from the noncovalent interaction of Br₂ with benzene (and toluene) reveal the unusual localized bonding to specific (one or two) carbon centers in prereactive complexes leading directly to the transition states for electrophilic aromatic brominations.

Photooxidation Of Polymeric-Inorganic Nanocomposites: Chemical, Thermal Stability And Fire Retardancy Investigations, Adams Tidjani, Charles A. Wilkie

Chemistry Faculty Research and Publications

Nanocomposites of polypropylene-graft-maleic anhydride/clay and polypropylene/clay were prepared by melt blending using two different approaches. X-Ray diffraction results showed an intercalated structure. Samples of nanocomposites were exposed to UV light under atmospheric oxygen and their photo-oxidative stability was studied using FTIR and UV spectroscopy. The consequences of this photo-oxidation on the thermal stability and fire retardant performance of the nanocomposites were also addressed from thermogravimetry analysis and Cone calorimetry.

An Xps Investigation Of Thermal Degradation And Charring Of Cross-Linked Polyisoprene And Polychloroprene, Jianwei Hao, Charles A. Wilkie, Jiangqi Wang

Chemistry Faculty Research and Publications

Our interest in butadiene-containing polymers had led to an investigation of the thermal degradation of polyisoprene, PIP, and polychloroprene, PCP. The connection between cross-linking and thermal stability through an examination of PIP and PCP has been reported. Like the course of thermogravimetric analysis (TGA) the cross-linking and charring of polymers subjected to heat can also be experimentally observed as function of temperatures by the pseudo-in-situ XPS (X-ray Photoelectron Spectroscopy). Data acquisition of C1s spectra as function of temperature permits us to explore: (1) the extent of cross-linking and/or carbon accumulation of systems of PCP and PIP with/without initiators, BPO and …

Synthesis Of Cyclopropanes Via Organoiron Methodology: Preparation Of 2-(2′-Carboxy-3′-Ethylcyclopropyl)Glycine, Kamil Godula, William A. Donaldson

Chemistry Faculty Research and Publications

A route to 1,2,3-trisubstituted cyclopropanes has been developed. The relative stereochemistry at the three cyclopropane centers is established by nucleophilic attack on the pentadienyl ligand on the face opposite to iron and subsequent oxidatively induced reductive elimination with retention of configuration. This methodology was applied to the synthesis of 2-(2′-carboxy-3′-ethylcyclopropyl)glycines. The diastereomeric glycine dimethyl esters are separable as their diphenylmethylene imines.

The conformationally restricted glutamate analogs (2S,1′S,2′S,3′R)- and (2R,1′S,2′S,3′R)-ECCG's 5a and5b were prepared in five steps (17 and 15% yield, respectively) from (pentadienyl)Fe(CO) …

Fire Retardancy In 2001, Gordon L. Wilson, Charles A. Wilkie

Chemistry Faculty Research and Publications

Fire is a world-wide problem which claims lives and causes significant loss of property. Some of the problems are discussed and the solution delineated. This peer-reviewed volume is designed to be as the state-of-the-art. This chapter provides a perspective for current work.

Electrochemistry And Spectroelectrochemistry Of Iron Porphyrins In The Presence Of Nitrite, Zhongcheng Wei, Michael D. Ryan

Chemistry Faculty Research and Publications

The reaction of nitrite with ferric and ferrous porphyrins was examined using visible, infrared and NMR spectroscopy. Solutions of either ferric or ferrous porphyrin were stable in the presence of nitrite, with only complexation reactions being observed. Under voltammetric conditions, though, a rapid reaction between nitrite and iron porphyrins was observed to form the nitrosyl complex, Fe(p)(NO), where P = porphyrin. The products of the reduction of ferric porphyrins in the presence of nitrite were confirmed by visible spectroelectrochemistry to be Fe(P)(NO) and [Fe(P)]2O. Visible, NMR and infrared spectroscopy were used to rule out the formation of Fe(P)(NO) by the …

Xps Characterization Of Friedel-Crafts Cross-Linked Polystyrene, Jiangqi Wang, Jianxin Du, Hongyang Yao, Charles A. Wilkie

Chemistry Faculty Research and Publications

The combination of a difunctional alkylating agent, either hydroxymethylbenzyl chloride or α,α′-dichloroxylene with polystyrene or high-impact polystyrene together with a Friedel-Crafts catalyst, 2-ethylhexyldiphenylphosphate, and an amine to react with hydrogen chloride has been studied by X-ray photoelectron spectroscopy. The results confirm what had been suggested from previous investigations using thermogravimetric analysis; cross-linking of the polymer occurs as the temperature is raised and the alcohol-containing alkylating agent gives a greater amount of cross-linking than does the dichloro compound.

The Thermal Stability Of Cross-Linked Polymers: Methyl Methacrylate With Divinylbenzene And Styrene With Dimethacrylates, Fawn Marie Uhl, Galina F. Levchik, Sergei V. Levchik, Caroline Dick, John J. Liggat, C.E. Snape, Charles A. Wilkie

Chemistry Faculty Research and Publications

Cross-linking of polymers is frequently presumed to enhance the thermal stability of polymer systems. Methyl methacrylate has been reacted with divinylbenzene and styrene with various dimethacrylates. These systems have been characterized by gel content, swelling ratio, infrared spectroscopy, thermal analysis, TGA/FT-IR, and solid state NMR. Both systems show enhanced thermal stability and char formation. This is most pronounced in the cases of methyl methacrylate with divinylbenzene and styrene with bisphenol A dimethacrylate.

Fire Properties Of Polystyrene-Clay Nanocomposites, Jin Zhu, Alexander B. Morgan, Frank K. Lamelas, Charles A. Wilkie

Chemistry Faculty Research and Publications

Polystyrene−clay nanocomposites have been prepared using a bulk polymerization technique. Three new “onium” salts have been used to prepare the nanocomposites, two are functionalized ammonium salts while the third is a phosphonium salt. By TGA/FTIR, both ammonium and phosphonium treatments have been shown to degrade by a Hofmann elimination mechanism at elevated temperatures. TGA/FTIR showed that the phosphonium treatment is the most thermally stable treatment when compared to the two ammonium salts. The nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, strength and elongation at break, as a measure of the mechanical properties, thermogravimetric analysis, and cone calorimetry. The …

Studies On The Mechanism By Which The Formation Of Nanocomposites Enhance Thermal Stability, Jin Zhu, Fawn Marie Uhl, Alexander B. Morgan, Charles A. Wilkie

Chemistry Faculty Research and Publications

Polystyrene−clay and polystyrene−graphite nanocomposites have been prepared and used to explore the process by which the presence of clay or graphite in a nanocomposite enhances the thermal stability of polymers. This study has been designed to determine if the presence of paramagnetic iron in the matrix can result in radical trapping and thus enhance thermal stability. Nanocomposites were prepared by bulk polymerization using both iron-containing and iron-depleted clays and graphites, and they were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, and cone calorimetry. The presence of structural iron, rather than that present as an impurity, significantly increases the …

Analysis Of Inorganic Materials Using Advanced Nmr And Nqr Techniques, Anthony Adrian Mrse

LSU Doctoral Dissertations

Several advanced solid-state nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) techniques have been applied to inorganic materials of commercial interest. The specific techniques applied to each system were chosen to solve specific obstacles which impeded the flow of industrial science.

First, the dispersion of brominated flame retardants in polymers is monitored using pulsed ⁸¹Br NQR (nuclear quadrupole resonance) techniques. The NQR spectrometer consists of a homemade NMR console and an automatically tuned loop-gap resonator probe. The two factors which affect the ⁸¹Br NQR transition frequencies of brominated aromatics are: electron-donating and withdrawing substituents on the ring …

The Coupling Of Biotechnology With Electrochemistry: Electrodenitrification Of Water Using The Enzyme Nitrate Reductase, Cyril Geyer

Dissertations and Theses @ UNI

Nitrate is a worldwide contaminant that causes environmental (eutrophication) and human health (methemoglobinemia, cancers) concerns. Very few techniques are available to eliminate it from natural environment and they suffer from major drawbacks, such as production of unwanted byproducts (toxins or brine). The electrochemical reduction of nitrate on any electrode is relatively slow and catalysts or electron mediators are needed. The goal of this project was to develop a new process that could overcome these disadvantages. The project demonstrates the feasibility of using an enzyme, nitrate reductase, and a mediator, methyl viologen to transfer the electrons from the electrode to nitrate, …