Chemistry Commons^™

Isomerization As A Key Path To Molecular Products In The Gas-Phase Decomposition Of Halons, Aimable Kalume, Lisa George, Scott A. Reid

Chemistry Faculty Research and Publications

The decomposition of halons remains controversial concerning the branching between radical and molecular products. The latter channel, where it has been found, is presumed to occur via a constrained symmetric multicenter transition state. Isomerization pathways in the gas-phase chemistry of halons have rarely been considered, despite the fact that the iso-halons, which feature a halogen−halogen bond, are widely recognized as important reactive intermediates in condensed phases. In this Letter, detailed calculations and modeling of the unimolecular decomposition of several important halons, including CF₂Cl₂, CF₂Br₂, and CHBr₃, reveal that isomerization is …

Tricarbonylrhenium(I) And Manganese(I) Complexes Of 2-(Pyrazolyl)-4-Toluidine, Brendan J Liddle, Sarath Wanniarachchi, Sergey V. Lindeman, James R. Gardinier

Chemistry Faculty Research and Publications

A series of tricarbonyl rhenium(I) and manganese(I) complexes of the electroactive 2-(pyrazolyl)-4-toluidine ligand, H(pzAn^Me), has been prepared and characterized including by single crystal X-ray diffraction studies. The reactions between H(pzAn^Me) and M(CO)₅Br afford fac-MBr(CO)₃[H(pzAn^Me)] (M = Mn, 1a; Re, 1b) complexes. The ionic species {fac-M(CH₃CN)(CO)₃[H(pzAn^Me)]}(PF₆) (M = Mn, 2a; Re, 2b) were prepared by metathesis of 1a or 1b with TlPF₆ in acetonitrile. Complexes 1a and 1b partly ionize to {M(CH₃CN)(CO)₃[H(pzAn^Me)]^{+ …}

Breaking The Cycle: Impact Of Sterically-Tailored Tetra(Pyrazolyl)Lutidines On The Self-Assembly Of Silver(I) Complexes, Tyler James Morin, Andrew Merkel, Sergey V. Lindeman, James R. Gardinier

Chemistry Faculty Research and Publications

A improved preparation of the pentadentate ligand α,α,α′,α′-tetra(pyrazolyl)lutidine, pz₄lut, and the syntheses of three new alkyl-substituted pyrazolyl derivatives pz^4′₄lut (pz4′ = 4-methylpyrazolyl), pz*₄lut (pz* = 3,5-dimethylpyrazolyl), and pz^DIP₄lut (pzDIP = 3,5-diisopropylpyrazolyl) are described. The silver(I) complexes of these ligands were studied to ascertain the impact of pyrazolyl substitution, if any, on their binding modes and on solubility issues. In the solid state, [Ag(pz₄lut)](BF₄) (1), [Ag(pz^4′4lut)](BF4) (2), and [Ag(pz*₄lut)](BF4) (3 …

A Shortened Synthesis Of Optically Pure Tricarbonyl[Methyl (2e,4e)-6-Oxo-2,4-Hexadienoate]Iron Leading To Improved Yield, Rajesh K. Pandey, Sergey V. Lindeman, William A. Donaldson

Chemistry Faculty Research and Publications

The (+)- and (–)-enantiomers of tricarbonyl[methyl (2E,4E)-6-oxo-2,4-hexadienoate]iron are prepared in 4 steps from commercially available hexadienal (26% and 25% yields, respectively).

Resin-Modified Glass-Ionomer Setting Reaction Competition, David W. Berzins, S. Abey, M. C. Costache, Charles A. Wilkie, H. W. Roberts

Chemistry Faculty Research and Publications

Resin-modified glass ionomers (RMGI) set by at least 2 mechanisms dependent upon reactant diffusion prior to gelation. Each reaction’s kinetics and setting mechanism may rely on and/or compete with the other. In this study, we investigated RMGI setting reaction interactions using differential scanning calorimetry (DSC) by varying light-cure initiation times. A RMGI was analyzed with isothermal and dynamic temperature scan DSC with light-curing occurring immediately, or at 5 or 10 minutes after mixing as well as without light-activation. Results show that as time allowed for the acid-base reaction increased, the light-activation polymerization exotherm decreased. Conversely, analysis of DSC data suggests …

Anion Exchange Kinetics Of Nanodimensional Layered Metal Hydroxides: Use Of Isoconversional Analysis, Stephen Majoni, Jeanne Hossenlopp

Chemistry Faculty Research and Publications

Anion exchange reactions of nanodimensional layered metal hydroxide compounds are utilized to create materials with targeted physical and chemical properties and also as a means for controlled release of intercalated anions. The kinetics of this important class of reaction are generally characterized by model-based approaches. In this work, a different approach based on isothermal, isoconversional analysis was utilized to determine effective activation energies with respect to extent of reaction. Two different layered metal hydroxide materials were chosen for reaction with chloride anions, using a temperature range of 30−60 °C. The concentrations of anions released into solution and the changes in …

Infrared Spectroelectrochemical Reduction Of Iron Porphyrin Complexes, Zhongcheng Wei, Michael D. Ryan

Chemistry Faculty Research and Publications

The spectroelectrochemistry of iron porphinones and their nitrosyl complexes were examined by infrared spectroscopy, as well as ferrous octaethylporphyrin nitrosyl. With the use of d₈-THF, the solvent was transparent down to 1200 cm⁻¹. For the porphinones, the reduction of the macrocycle ring could be observed by the changes in the ν_CO band and, for the nitrosyl complex, the changes in the nitrosyl ligand were directly observable from the ν_NO band. Formation of the ferrous complexes led to a small downshift in the ν_CO band. Further reduction to the formal Fe(“I”) complex led to …

Thermal Degradation Studies On Pmma–Het Acid Based Oligoesters Blends, Thangamani Rajkumar, Chinnaswamy Thangavel Vijayakumar, Palanichamy Sivasamy, Bojja Sreedhar, Charles A. Wilkie

Chemistry Faculty Research and Publications

Imparting thermal stability to polymethyl methacrylate (PMMA) without affecting its optical clarity is attempted by incorporating HET acid based oligoesters. Pure PMMA and PMMA containing five and 20 wt% of four different oligoesters are separately prepared using bulk polymerization. The thermal properties of the materials studied using DSC, TG, TG–FTIR and Pyr–GC–MS are presented. The main volatile degradation products identified are CO, HCl, CO₂, H₂O, hexachlorocyclopentadiene, hexachloroendomethylene tetrahydrophthalic acid/anhydride and methyl methacrylate. A detailed mechanism for the influence of the degradation products of HET acid based oligoesters on the thermal degradation of PMMA is also presented.

Immobilization Of Motile Bacterial Cells Via Dip-Pen Nanolithography, Dorjderem Nyamjav, Sergey Rozhok, Richard C. Holz

Chemistry Faculty Research and Publications

A strategy to bind bacterial cells to surfaces in a directed fashion via dip-pen nanolithography (DPN) is presented. Cellular attachment to pre-designed DPN generated microarrays was found to be dependent on the shape and size of the surface feature. While this observation is likely due in part to a dense, well formed mercaptohexadecanoic acid (MHA) monolayer generated via DPN, it may also simply be due to the physical shape of the surface structure. Motile Pseudomonas aeruginosa bacterial cells were observed to bind to DPN generated mercaptohexadecanoic acid/poly-L-lysine (MHA/PLL) line patterns, 'blocks' made up of eight lines with 100 nm spacings, …

Cross-Talk-Free Dual-Color Fluorescence Cross-Correlation Spectroscopy For High-Throughtput Screening, Wonbae Lee

LSU Doctoral Dissertations

High throughput processing of chemical/biochemical information is critical in many areas, such as genome sequencing, drug discovery and clinical diagnostics. Integral to collecting information at high rates with the necessary throughput is the development of systems that can not only monitor the results with high precision and accuracy, but also prepare and process samples prior to the analytical measurement. To achieve the required throughput, we have conducted work directed toward developing a system that provides detection sensitivity at the single-molecule detection (SMD) level. The research was first focused on the development of a sensitive strategy for the detection of proteins …

Dissolution Of Chitosan In Ionic Liquids For Acylation Chemistry And Formation Of Cellulose-Chitosan Blends, Cristina Stefanescu

LSU Doctoral Dissertations

Dissolution of chitosan in ionic liquids was accomplished. It has been shown that 1-butyl-3-methylimidazolium acetate (BMIMAc) is a better solvent than 1-butyl-3-methylimidazolium chloride (BMIMCl). Dissolution of chitosan in BMIMCl required a prior regeneration of chitosan from 1% acetic acid solution. In the case of BMIMAc, both dried chitosan and regenerated chitosan from acetic acid solution have been dissolved in a relatively short amount of time. While concentrations up to 2 wt% of chitosan in BMIMCl could be obtained, concentrations of 10 wt % of chitosan in BMIMAc were realized. Homogeneous phthalation and benzoylation of chitosan were achieved in these ionic …

Chemistry Of Rhenium(I) Tricarbonyl Complexes Of Biomedical Relevance, Theshini Perera

LSU Doctoral Dissertations

fac-[Re^I(CO)₃L]ⁿ complexes serve as models for short-lived fac-[^99mTc^I(CO)₃L] imaging tracers. Dangling groups on L, needed to achieve desirable biodistribution, complicate the NMR spectra, which are not readily understood. In fac-[Re^I(CO)₃L]⁺ with less complicated L, NH groups (exo-NH) projecting toward the L face sometimes showed an upfield shift attributable to steric shielding of the exo-NH group from the solvent by the chelate rings. To investigate whether exo-NH groups in six-membered rings exhibit the same effect and whether the …

Computer Simulation Of Ion-Induced Nucleation In The Presence Of Single Ions And Ion Pairs, Samuel Keasler

LSU Doctoral Dissertations

Atmospheric aerosol particles play an important role in climate and human health. Despite their importance, the mechanisms of their formation are still poorly understood. Ion-induced nucleation may play a role in the process, but details are lacking about how the nucleation rate depends on the size, charge, and number of ions in the cluster. In order to better understand the role that ions might play in new particle formation, we have performed a series of AVUS-HR simulations of the water nucleation in the presence of both single ions and ion pairs. These simulations have shown that the location of the …

Highly Efficient Selection, Enumeration, Enrichment, And Molecular Profiling Of Low-Abundance Biological Cells, Udara R. Dharmasiri Rasika Dharmasiri

LSU Doctoral Dissertations

After brief overviews of low-abundance cell selection techniques in chapter 1 and circulating tumor cells in chapter 2, this dissertation initially focuses on the development of aptamer incorporated high-throughput microfluidic techniques to select rare circulation prostate cancer cells (LNCaP) directly from whole blood with subsequent quantification of these rare cells using a non-labeling approach. Then, I extended the technology to environmental samples in an effort around time, sensitivity, and portability of traditional groundwater assessment. As a model bio- pathogen, E. coli O157:H7 was chosen due to its toxicity and its adverse impact on recreational waters. Low-abundance (<100 cells mL-1) E. coli O157:H7 cells were isolated and enriched from environmental water samples using a microfluidic chip that its capture beds were covalently decorated with E.coli O157:H7 specific polyclonal antibodies. The selected cells were enumerated using RT-qPCR technique. Finally, I have integrated HTMSU with electrokinetic enrichment microfluidic unit for performance of single recombinant low-abundance CTC cell-based assay. A series of analytical processes were carried out, including immunoaffinity selection of rare CTCs, quantification of selected cells via conductivity impedance and electrophoretic enrichment of selected cells for PCR/LDR/CE interrogation for detection of low-abundance point mutations in genomic DNA.

A Study Of The Interactions Of Lipid Bilayers And Dendrimers Using Small Angle X-Ray Scattering And Freeze Fracture Transmission Electron Microscopy, Derek R. Dorman

LSU Doctoral Dissertations

Lipids are fundamental to all life forms, a key component of cell walls, and essential to proper respiratory function. They are amphiphilic molecules and readily form bilayers. Dendrimers are designer molecules that can be tailored to provide a variety of endgroup moieties, sizes, and charges. The interaction of liposomes and dendrimers can provide information on how medicine interacts with cells and an array of unique structures can be imagined from their assembly into superstructures. Polypropylenimine tetraamine (DAB-Am) and 1-directional arborol dendrimers have been studied in different molar concentrations with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers. One-directional arborols are amphiphilic dendrimers with a hydrophilic …

Isolation And Characterization Of Ligands For The Goldfish Testicular Androgen Receptor From Kraft Mill Chemical Recovery Condensates, Philip David Scott

Theses and Dissertations (Comprehensive)

An investigation of cause was started in the 1990s at a bleached Kraft mill (BKM), located in Saint John NB, Canada. The 5th effect chemical recovery condensates waste stream (derived from wastewater generated during the pulping process) was identified as having the greatest potential for affecting mummichog (Fundulus heteroclitus), compared to the rest of the inmill waste streams. A solid phase extraction (SPE) protocol was utilized to isolate the causative chemicals in the condensate stream. Goldfish testicular androgen receptors (ARs) were exposed to five extracts: filter paper non-polar/polar, solid phase extraction nonpolar/polar, and residual condensates. The filter paper …

Microporous Organic Polymers: Synthesis And Post Synthetic Modifications, Phillip Andrew Kerneghan

Theses and Dissertations (Comprehensive)

Microporous solids are an important class of materials that have been studied extensively. Newer to this field are Microporous Organic Polymers (MOPs) which are networks constructed from smaller organic building blocks and exhibit large surface areas, small pore sizes and low densities. It is due to these characteristics that MOPs have attracted attention because of their potential use in applications such as catalysis, chemical separations and gas storage.

In this thesis is described the synthesis of two novel MOPs, the first of which being a network based on benzenediboronic acid and triptycene building blocks linked together by boronate esters. This …

Identification Of Virulence Genes In The Corn Pathogen Fusarium Verticillioides, Divya Chouhan

Dissertations and Theses @ UNI

Fusarium verticillioides is a pathogenic fungus that causes infection of crops and vegetables such as corn, wheat, potato, cassava, banana, potato and sorghum. It causes various diseases in corn such as seedling blight, root, stalk, and ear rot. Pathogenic Fusarium species have caused billions of dollars of damage through reduced yield. F.verticillioides also produces mycotoxins such as fumonisin. Consumption of contaminated grain can cause various diseases in animals such as pulmonary oedema in pigs and leukoencephalomalacia in horses, and may be associated with esophageal cancer in humans. Identification of virulence genes in F. verticillioides will help in understanding its biology …