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2008

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Articles 691 - 713 of 713

Full-Text Articles in Chemistry

A Tour-De-Force In Polymer Crosslinked Aerogels, Sudhir Mulik Jan 2008

A Tour-De-Force In Polymer Crosslinked Aerogels, Sudhir Mulik

Doctoral Dissertations

"In the quest of building mechanically strong materials with low density and high porosity, polymer crosslinked aerogels stand as the most promising nano-engineered examples. Covalent attachment of polymers and bridging of skeletal nanoparticles of typical aerogels is demonstrated by using surface initiated polymerization (SIP) with a bidentate free-radical initiator structurally related to azobisisobutyronitrile (AIBN) and confined on mesoporous silica surfaces. Different monomers were introduced in the mesopores and upon heating at 70⁰C, all mesoporous surfaces throughout the entire skeletal framework were coated conformally with a 10-12 nm thick polymer layer indistinguishable spectroscopically from the respective commercial bulk materials. The new …

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The Effect Of Free Chlorine And Monochloramine On Lead In Drinking Water And Epitaxial Electrodeposition Of Tin Sulfide, Sansanee Boonsalee Jan 2008

The Effect Of Free Chlorine And Monochloramine On Lead In Drinking Water And Epitaxial Electrodeposition Of Tin Sulfide, Sansanee Boonsalee

Doctoral Dissertations

"Electrochemical deposition is utilized in various electronic and photovoltaic applications and in the protective coating industries. This dissertation primarily addresses the environmental aspects of electrochemical deposition. In the first part of this study, Pb dissolution in drinking water was investigated in the presence of two disinfectants: free chlorine (in the form of HOCI/OCr) and monochloramine (NH₂Cl). In the second part of this study, epitaxial SnS nanodisks were electrodeposited onto a Au(100) substrate. Water utility systems use either free chlorine or monochloramine in their disinfection program. Whereas free chlorine reacts with natural organic matter in the water to produce halogenated organic …

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Synthesis And Evaluation Of Vegetable (Soybean) Oil Based Epoxy Resin For Beverage Can Coating And Enzymatic Synthesis And Characterization Of Tailored N&C End Protected Oligopeptides, Ying Gao Jan 2008

Synthesis And Evaluation Of Vegetable (Soybean) Oil Based Epoxy Resin For Beverage Can Coating And Enzymatic Synthesis And Characterization Of Tailored N&C End Protected Oligopeptides, Ying Gao

Doctoral Dissertations

"Research described in this dissertation covers two topics. Part-I is related to the development of a soybean oil based epoxy resin and its application in beverage can coatings. Interior surfaces of beverage can are invariably coated with polymer coating. The most commonly used coatings at present are derived from bisphenol A (BPA) based epoxy reins. However, due to perceived endocrine disrupting nature of BPA and consequential adverse effects on humans and wildlife concerns for the use of BPA based coatings and its leaching into beverages have been expressed. The research in the first part describes the synthesis and evaluation of …

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Retro Models Of The Cisplatin-Dna Cross-Link With Carrier Ligands Having Sp2 N-Donor Triazine Rings, Vidhi Maheshwari Jan 2008

Retro Models Of The Cisplatin-Dna Cross-Link With Carrier Ligands Having Sp2 N-Donor Triazine Rings, Vidhi Maheshwari

LSU Doctoral Dissertations

Rapid rotation of guanine base derivatives about Pt–N7 bonds results in fluxional behavior of models of the key DNA intrastrand G–G cross-link leading to anticancer activity of Pt(II) drugs (G = deoxyguanosine). This behavior impedes the characterization of LPtG2 models (L = one bidentate or two cis-unidentate carrier ligands; G = guanine derivative). The objective of this study is to understand the types of conformers formed as L is systematically varied. This work, relevant to Pt(II) anticancer drugs, has evolved from published studies with sp3 N-ligands (e.g., 2,2'-bipiperidine), to C2 symmetrical or unsymmetrical sp2 N-ligands having pyridine and/or triazine rings. …

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Development Of New Stimuli-Responsive Vesicles Using A Novel Surfactant, Yuming Yang Jan 2008

Development Of New Stimuli-Responsive Vesicles Using A Novel Surfactant, Yuming Yang

LSU Doctoral Dissertations

Many amphiphilic molecules (surfactants) possess the ability to aggregate in aqueous solution to form thermodynamically stable aggregates that have potential for use as molecule containers and delivery systems in analytical or pharmaceutical applications. However, it is difficult to release the encapsulated molecules from these aggregates under a controllable manner, and this problem has dramatically limited the application of these aggregated systems. This study addresses this problem through fundamental structure modification by development of a novel redox stimuli-responsive amphiphile capable of forming vesicle aggregates. Aggregate structure can be adjusted through redox stimulation. The release of agents from the core of the …

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Size-Controlled Synthesis Of Monodisperse Core/Shell Nanogels, William H. Blackburn, L. Andrew Lyon Jan 2008

Size-Controlled Synthesis Of Monodisperse Core/Shell Nanogels, William H. Blackburn, L. Andrew Lyon

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Small, monodisperse nanogels (similar to 50-nm radius) were synthesized by free-radical precipitation polymerization and were characterized using a suite of light scattering and chromatography methods. Nanogels were synthesized with either N-isopropylacrylamide or N-isopropylmethacrylamide as the main monomer, with acrylic acid or 4-acrylamidofluorescein as a comonomer and N,N'-methylenebis(acrylamide) as a cross-linker. By varying the surfactant and initiator concentrations, particle size was controlled while maintaining excellent monodispersity. An amine-containing shell was added to these core particles to facilitate subsequent bioconjugation. Successful conjugation of folic acid to the particles was demonstrated as an example of how such materials might be employed in a …

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Incorporation Of Cα,Α-Disubstituted Amino Acids Into Model Peptide Systems: Conformational Analysis And Possible Applications As Therapeutic Agents, Marcus A. Etienne Jan 2008

Incorporation Of Cα,Α-Disubstituted Amino Acids Into Model Peptide Systems: Conformational Analysis And Possible Applications As Therapeutic Agents, Marcus A. Etienne

LSU Doctoral Dissertations

A diverse set of human diseases is associated with the misfolding of proteins into insoluble fibrillar structures that have predominantly β-sheet secondary structure. Thus it is imperative to elucidate the structural elements that contribute to β-sheet formation and stability. Peptides that autonomously form β-sheets are ideal models to study principles of protein folding and design. Gellman and coworkers first introduced an automonously folded β-hairpin (H-Arg-Tyr-Val-Glu-Val-Yyy-Xxx-Orn-Lys-Ile-Leu-Gln-NH2) that remained monomeric up to ~1 mM. Circular dichroism (CD) and nuclear magnetic resonance (NMR) analyses revealed that incorporation of non-stereogenic Aib-Xxx dipeptidyl sequences into i+1 and i+2 positions of a model peptide nucleates a …

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Reactivity Of (2-Alkenyl-3-Pentene-1,5-Diyl)Iron Complexes: Preparation Of Functionalized Vinylcyclopropanes And Cycloheptadienes, Rajesh K. Pandey, Lizhu Wang, Nathaniel J Wallock, Sergey V. Lindeman, William A. Donaldson Jan 2008

Reactivity Of (2-Alkenyl-3-Pentene-1,5-Diyl)Iron Complexes: Preparation Of Functionalized Vinylcyclopropanes And Cycloheptadienes, Rajesh K. Pandey, Lizhu Wang, Nathaniel J Wallock, Sergey V. Lindeman, William A. Donaldson

Chemistry Faculty Research and Publications

The reactivity of (2-alkenyl-3-pentene-1,5-diyl)iron complexes toward olefin metathesis, cycloaddition, and mild oxidations (MnO2 or mCPBA) was examined. Cycloaddition reactions were observed to occur with modest diastereoselectivity (33−63% de). Decomplexation of the (3-pentenediyl) ligand may be accomplished by oxidation with either CAN or alkaline hydrogen peroxide to afford vinylcyclopropanecarboxylates or divinylcyclopropanecarboxylates. Reduction of the latter, followed by Cope rearrangement generates cycloheptadienylmethanols. These studies demonstrate that (2-alkenyl-3-pentene-1,5-diyl)iron complexes can serve as organometallic scaffolds for the preparation of a wide variety of structural motifs containing up to 5 contiguous stereocenters.

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A Tribute To Peter George Brewer In Celebration Of His 65th Birthday, George T. F. Wong, Robert F. Anderson, Michael P. Bacon, Hein J. W. De Baar, James W. Murray, Mary I. Scranton Jan 2008

A Tribute To Peter George Brewer In Celebration Of His 65th Birthday, George T. F. Wong, Robert F. Anderson, Michael P. Bacon, Hein J. W. De Baar, James W. Murray, Mary I. Scranton

OES Faculty Publications

Peter George Brewer is an ocean chemist of the rare breed that can cross back and forth over the divide between being a front-line research scientist and being a research executive. As if that is not remarkable enough, in the process, he has also demonstrated sustained growth in the depth, breadth, and diversity of his scientific endeavors. Some of his formidable contributions to ocean chemistry have already been highlighted in a profile of him as a major mover and shaker in the field (Irion, 2001). Here, we provide additional glimpses of him from the perspective of a group of individuals …

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Characterization Of Microorganisms Of Interest To Homeland Security And Public Health Utilizing Liquid Chromatography/Mass Spectrometry, Robert A. Everley Jan 2008

Characterization Of Microorganisms Of Interest To Homeland Security And Public Health Utilizing Liquid Chromatography/Mass Spectrometry, Robert A. Everley

Theses and Dissertations

Liquid chromatography/quadrupole time of flight mass spectrometry (LC/QTOF MS) utilizing electrospray ionization was employed to monitor protein expression in Escherichia coli and Shigella organisms. Automated charge state deconvolution, spectral subtraction and spectral mirroring were used to reveal subtle differences in the LC/MS data. Reproducible intact protein biomarkers were discovered based on their unique mass, retention time and relative intensity. These markers were implemented to differentiate closely related strain types, (e.g. two distinct isolates of E. coli O157:H7) and to correctly identify unknown pathogens. Notable, was the distinction of multiple serotypes of enterohaemorrhagic E. coli which cannot be distinguished by clinical …

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Double Carbon−Hydrogen Activation Of 2-Vinylpyridine: Synthesis Of Tri- And Pentanuclear Clusters Containing The Μ-Nc5H4Ch═C Ligand, Kazi A. Azam, Dennis W. Bennett, Mohammad R. Hassan, Daniel T. Haworth, Graeme Hogarth, Shariff E. Kabir, Sergey V. Lindeman, Luca Salassa, Sultana R. Simi, Tasneem Siddiquee Jan 2008

Double Carbon−Hydrogen Activation Of 2-Vinylpyridine: Synthesis Of Tri- And Pentanuclear Clusters Containing The Μ-Nc5H4Ch═C Ligand, Kazi A. Azam, Dennis W. Bennett, Mohammad R. Hassan, Daniel T. Haworth, Graeme Hogarth, Shariff E. Kabir, Sergey V. Lindeman, Luca Salassa, Sultana R. Simi, Tasneem Siddiquee

Chemistry Faculty Research and Publications

Reactions of 2-vinylpyridine with the triruthenium complexes [Ru3(CO)12] and [Ru3(CO)10(μ-dppm)] leads to a previously unknown double carbon−hydrogen bond activation of the β-carbon of the vinyl group to afford the pentaruthenium and triruthenium complexes [Ru5(CO)14(μ4-C5H4CH═C)(μ-H)2] (1) and [Ru3Cl(CO)5(μ-CO)(μ-dppm)(μ3-NC5H4CH═C)(μ-H)] (2), respectively. Crystal structures reveal two different forms of bridging of the dimetalated 2-vinylpyridyl ligand, capping a square face in 1 and a triangular face in 2.

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Isolation And X-Ray Structural Characterization Of Tetraisopropylpyrene Cation Radical, Moloy Banerjee, Vijay Vyas, Sergey V. Lindeman, Rajendra Rathore Jan 2008

Isolation And X-Ray Structural Characterization Of Tetraisopropylpyrene Cation Radical, Moloy Banerjee, Vijay Vyas, Sergey V. Lindeman, Rajendra Rathore

Chemistry Faculty Research and Publications

A practical synthesis of 1,3,6,8-tetraisopropylpyrene and the isolation and X-ray structural characterization of its monomeric cation radical salt are described.

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Aluminum-Containing Layered Double Hydroxides: The Thermal, Mechanical, And Fire Properties Of (Nano)Composites Of Poly(Methyl Methacrylate), Charles Manzi-Nshuti, Dongyan Wang, Jeanne Hossenlopp, Charles A. Wilkie Jan 2008

Aluminum-Containing Layered Double Hydroxides: The Thermal, Mechanical, And Fire Properties Of (Nano)Composites Of Poly(Methyl Methacrylate), Charles Manzi-Nshuti, Dongyan Wang, Jeanne Hossenlopp, Charles A. Wilkie

Chemistry Faculty Research and Publications

Hydrotalcite-like anionic clays or layered double hydroxides (LDHs) of the general formula, [MII1-xMIIIx(OH)2]intra[(CH2=CH(CH2)8COO-)x•nH2O]inter, with MIII = Al and MII = Co, Ni, Cu, and Zn, have been prepared by the co-precipitation method and used to prepare nanocomposites with poly(methyl methacrylate) (PMMA). One goal of this work was to compare the morphology, thermal, fire and mechanical properties with those of the well known PMMA–montmorillonite system. The thermal properties of these systems are greatly …

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Het Acid Based Oligoesters – Tga/Ftir Studies, Thangamani Rajkumar, Chinnaswamy Thangavel Vijayakumar, Palanichamy Sivasamy, Charles A. Wilkie Jan 2008

Het Acid Based Oligoesters – Tga/Ftir Studies, Thangamani Rajkumar, Chinnaswamy Thangavel Vijayakumar, Palanichamy Sivasamy, Charles A. Wilkie

Chemistry Faculty Research and Publications

One of the important reactive halogenated dicarboxylic acids used in the synthesis of flame retardant unsaturated polyester resins is 1,4,5,6,7,7-hexachlorobicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid (HET acid). In the present investigation four different oligoesters are synthesized using HET acid as the diacid component and 1,2-ethane diol, 1,2-propane diol, 1,3-propane diol and 1,4-butane diol as the aliphatic diols. Melt condensation technique in vacuum is used for the synthesis of the oligoesters. The number average molecular weights of the oligoesters are determined using end group analysis. The degree of polymerization is estimated to be 3–5. The structural characterization is done using FTIR and NMR …

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Polymerically Modified Layered Silicates: An Effective Route To Nanocomposites, Jinguo Zhang, Evangelos Manias, Charles A. Wilkie Jan 2008

Polymerically Modified Layered Silicates: An Effective Route To Nanocomposites, Jinguo Zhang, Evangelos Manias, Charles A. Wilkie

Chemistry Faculty Research and Publications

Polymer/clay nanocomposites have been under an extensive investigation for about 15 years. Traditional methods to modify the clay are usually limited to small organic cations, preferably containing long alkyl chain(s), which are exchanged with the inorganic cations in the clay gallery. This article provides a comprehensive review on the strategies for clay modification using polymeric surfactants or polycations: from the synthesis of such surfactants, through the preparation of the polymerically modified clays, and to the fabrication of the respective polymer nanocomposites and their properties.

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Synthesis, Electronic Properties, And X-Ray Structural Characterization Of Tetrarylbenzo[1,2-B:4,5-B′]Difuran Cation Radicals, Ruchi Shukla, Shriya Wadumethrige, Sergey V. Lindeman, Rajendra Rathore Jan 2008

Synthesis, Electronic Properties, And X-Ray Structural Characterization Of Tetrarylbenzo[1,2-B:4,5-B′]Difuran Cation Radicals, Ruchi Shukla, Shriya Wadumethrige, Sergey V. Lindeman, Rajendra Rathore

Chemistry Faculty Research and Publications

Electroactive tetraarylbenzo[1,2-b:4,5-b′]difuran (BDF) and model diarylbenzofuran derivatives are synthesized and their structures are established by X-ray crystallography. Isolation and X-ray crystallographic characterization of the robust cation-radical salts of BDF derivatives confirm that a single charge in the BDFs is stabilized largely by the benzodifuran and coplanar α-aryl groups lying on the longitudinal axis. These findings suggest that the linear arrays of BDFs may allow the construction of molecular wires suitable for long-range electron transport.

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Kinetic, Spectroscopic, And X-Ray Crystallographic Evidence For The Cooperative Mechanism Of The Hydration Of Nitriles Catalyzed By A Tetranuclear Ruthenium-Μ-Oxo-Μ-Hydroxo Complex, Chae S. Yi, Tonya N. Zeczycki, Sergey V. Lindeman Jan 2008

Kinetic, Spectroscopic, And X-Ray Crystallographic Evidence For The Cooperative Mechanism Of The Hydration Of Nitriles Catalyzed By A Tetranuclear Ruthenium-Μ-Oxo-Μ-Hydroxo Complex, Chae S. Yi, Tonya N. Zeczycki, Sergey V. Lindeman

Chemistry Faculty Research and Publications

The tetranuclear ruthenium-oxo-hydroxo-hydride complex {[(PCy3)(CO)RuH]4(μ4-O)(μ3-OH)(μ2-OH)} (1) was found to be a highly cooperative catalyst for the nitrile hydration reaction. The cooperative mechanism of the hydration of benzonitrile was established by Hill inhibition kinetics. The treatment of a nitrile substrate with complex 1 led to the catalytically relevant nitrile-coordinated tetraruthenium complex 3. The X-ray structure of the nitrile-coordinated complex 3 showed a considerably “relaxed” tetrameric core structure compared to that of 1. The hydration of para-substituted benzonitriles p-X-C6H4CN with an electron-withdrawing …

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A Second-Generation Janus Scorpionate Ligand: Controlling Coordination Modes In Iron(Ii) Complexes By Steric Modulation, Rosalice M. Silva, Chengeto Gwengo, Sergey V. Lindeman, Mark D. Smith, Gary J. Long, Fernande Grandjean, James R. Gardinier Jan 2008

A Second-Generation Janus Scorpionate Ligand: Controlling Coordination Modes In Iron(Ii) Complexes By Steric Modulation, Rosalice M. Silva, Chengeto Gwengo, Sergey V. Lindeman, Mark D. Smith, Gary J. Long, Fernande Grandjean, James R. Gardinier

Chemistry Faculty Research and Publications

The second-generation Janus scorpionate ligand [HB(mtdaMe)3−] containing methyl-mercaptothiadiazolyl (mtdaMe) heterocyclic rings and (N,N,N-) and (S,S,S-) binding pockets has been prepared. The effect of methyl substitution versus the unsubstituted first-generation Janus scorpionate [HB(mtda)3]− on the coordination chemistry with alkali metals and on the binding preferences and on the ground spin state of iron(II) complexes has been studied structurally and by 57Fe Mossbauer Spectroscopy.

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Chemical Analysis Of Polymer Blends Via Synchrotron X-Ray Tomography, Heath Alan Barnett Jan 2008

Chemical Analysis Of Polymer Blends Via Synchrotron X-Ray Tomography, Heath Alan Barnett

LSU Doctoral Dissertations

Material properties of industrial polymer blends are of great importance. X-ray tomography has been used to obtain spatial chemical information about various polymer blends. The spatial images are acquired with synchrotron X-ray tomography because of its rapidity, good spatial resolution, large field-of-view, and elemental sensitivity. The spatial absorption data acquired from X-ray tomography experiments is converted to spatial chemical information via a linear least squares fit of multi-spectral X-ray absorption data. A fiberglass-reinforced polymer blend with a new-generation flame retardant is studied with multi-energy synchrotron X-ray tomography to assess the blend homogeneity. Relative to other composite materials, this sample is …

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Concentration Of Phosphorylated Proteins Using Modified Pmma Microanalytical Devices, Jowell Guerra Bolivar Jan 2008

Concentration Of Phosphorylated Proteins Using Modified Pmma Microanalytical Devices, Jowell Guerra Bolivar

LSU Doctoral Dissertations

This work describes the application of PMMA-based microanalytical devices for the affinity-type preconcentration of posttranslational modified proteins (PTMs). The choice of poly(methyl methacrylate), PMMA, is based on its biocompatibility, its functional methyl ester group for potential modification, and its extensive applications to create biological microelectromechanical systems (BioMEMS). Developing methodologies for preconcentration of PTMs is important for cancer diagnosis due to PTMs’ influence in the regulatory mechanism underlying the early stage of apoptosis or regulated cell death. Towards this goal, nitroavidin which can reversibly binds to biotin (and biotinylated proteins), was prepared using reported procedure and was characterized using several techniques …

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Syntheses Of Trimethylamine- And Phosphonate- Substituted Carboranylporphyrins For Application In Boron Neutron Cancer Therapy, Michael William Easson Jan 2008

Syntheses Of Trimethylamine- And Phosphonate- Substituted Carboranylporphyrins For Application In Boron Neutron Cancer Therapy, Michael William Easson

LSU Doctoral Dissertations

Chapter 1 contains an introduction to porphyrins and carboranylporphyrins, including their physical properties, history, methods of synthesis, medicinal applications, and an overview of recently published compounds. Chapter 2 contains the total synthesis of a series of trimethylamine- and phosphonate-substituted carboranylporphyrins for application in boron neutron capture therapy (BNCT), including characterization by proton nuclear magnetic resonance spectroscopy, matrix-assisted time-of-flight mass spectroscopy, high resolution mass spectroscopy, UV-Vis spectrophotometry, X-ray crystallography, and melting point apparatus. Chapter 3 contains synthetic methods which were investigated as alternate routes to porphyrin synthesis and functionalization. Chapter 4 presents the in vitro biological evaluation of trimethylamine- and phosphonate-substituted …

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Syntheses And Evaluation Of Phthalocyanine Derivatives For Applications In Photodynamic And Boron Neutron Capture Therapies For Cancer, Hairong Li Jan 2008

Syntheses And Evaluation Of Phthalocyanine Derivatives For Applications In Photodynamic And Boron Neutron Capture Therapies For Cancer, Hairong Li

LSU Doctoral Dissertations

Chapter I introduced the background of phthalocyanines including its physical properties and various synthetic methods of free-base and metallo-phthalocyanines. The background of PDT and BNCT was introduced and the objective of ideal sensitizers was described. Chapter II described the synthesis and characterization of a series of pyridiloxy-substituted zinc phthalocyanines with different length of alkyl groups. Pyridiloxy-substituted silica phthalocyanines bearing different associated axial ligands, were alkylated with methyl or PEG chains. Biological study was performed on these cationic pyridiloxy-substituted zinc phthalocyanines. Chapter III introduced the synthesis and photophysical properties of A3B-type zinc phthalocyanines conjugated with one or two cobalta-carborane cages. They …

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Synthesis And Characterization Of New Luminescent Late Transition Metal Complexes Containing The Tridentate 1,3-Di(N-Pyrazolyl)-4,6-Dimethyl Benzene Ligand, Brian Christopher Gruver Jan 2008

Synthesis And Characterization Of New Luminescent Late Transition Metal Complexes Containing The Tridentate 1,3-Di(N-Pyrazolyl)-4,6-Dimethyl Benzene Ligand, Brian Christopher Gruver

Dissertations and Theses @ UNI

The tridentate 1,3-di(N-pyrazolyl) benzene L 1 was synthesized from dibromobenzene and pyrazole. When reacted with K2PtC14 and IrCl3 the asymmetric complexes (µ-Cl)2(PtL1 )2 and (µ-Cl)2[lr L12]2 were obtained. The tridentate l ,3- dimethyl-4,6-(di-N-pyrazolyl) benzene ligand L2 , was synthesized from di-bromo-mxylene and pyrazole. The ligand was reacted with K2PtC14 to give L2 PtCl. Further reaction with phenylacetylene led to the air sensitive acetylide complex L2 PtC=C(C6H5). L2 PtCl could also be reacted with AgOTf in acetonitrile to give [L2 PtN=CCH3] OTf. Reaction with other late transition metals led to the di-chloro bridged iridium dimer (µ-Cl)2[L 2IrCl]2 and the square planar …

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