Chemistry Commons^™

Stability Of Heme Proteins: Cytochrome C And Horseradish Peroxidase, Mini Gupta

Masters Theses

A heme protein is a metalloprotein containing the heme prosthetic group. This prosthetic group is responsible for the wide range of biological functions found in heme proteins, from oxygen transport to electron transport. Moreover, heme proteins show a fascinating range of folding architectures, leading to their interest in research on structure-function relationships. The objective of this research in bioinorganic chemistry is to study the structural stability of two heme proteins, iron cytochrome c (Fecyt) and horseradish peroxidase (HRP). Absorbance spectroscopy is used to monitor the structural changes in the protein environment around the heme prosthetic group.

With just a change …

Electrochemical And Spectroscopic Characterization Of A Polypyridyl Ru(Ii) Complex Containing A Fused Alloxazine, Waynie Wilson Olaprath

Masters Theses

Phenanthroline pteridinedione (pptd) is an alloxazine derivative capable of 2e/ 2H+ transfer reactions. Coordination of pptd to a Ru(II) metal center allows for the synthesis of water-soluble metal complexes capable of being reduced by as many as 6 Hatoms making them candidates to be electrochemical mediators. This thesis describes the synthesis and characterization of pptd and [Ru(bpy)2(pptd)](PF6)2(b py = 2,2-bipyridine). The dipyrido[3,2-a: 1' ,2' -c] phenazine (d ppz) and [Ru(bpy)2(d ppz) ](PF6)2 are also synthesized and studied in order to distinguish the properties of the free and coordinated pteridinedione-based pptd ligand from the well-characterized phenazine based ligand.

Detailed cyclic voltammetry, …

Molecular Structures And Pulsed Discharge Emission Studies Of Volatile Organic Compound Derivatives, Ashley Osthoff

Masters Theses

Understanding the structure and reactivity of volatile organic compounds (VOCs), hydrochlorofluorocarbons (HCFCs) and their derivatives is a fundamental concern in the study of atmospheric chemistry. Recently, a series of studies were done aimed at constructing and optimizing a rapid-scan, midinfrared spectrometer in order to study the structure and intermolecular interactions of these compounds. Visible emission spectroscopy was used to optimize the pulsed discharge nozzle that would be used within the infrared spectrometer. The emission spectra of toluene and xylene were used to characterize production of free radical compounds. In addition, control programs were written in the Lab VIEW programming language …

Study Of Corrosion Of Materials In The Sulfur-Iodine Hydrogen Production Cycle, Thao Trung Ho

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen is of great interest since the availability of traditional fossil fuels is in decline. Strictly speaking, hydrogen is not a primary source of energy but is an energy carrier, since energy typically must be used from another source (electricity, natural gas, coal, etc.) to produce it. Of hydrogen production techniques, the Sulfur-Iodine thermochemical water splitting process (S-I cycle), which was proposed by General Atomics (GA), is promising with its simplicity and high efficiency. Most of the chemicals are recycled except water. However, the S-I cycle operates in a harsh, corrosive environment in the presence of a mixture of iodine …

Optimization Of The Microprecipitation Procedure For Nuclear Forensics Applications, Lyndsey Renee Kelly

UNLV Theses, Dissertations, Professional Papers, and Capstones

Microprecipitation has become one of the most widely used sample preparation techniques for alpha spectroscopy. Many factors during the precipitation process can affect the yield and energy resolution by adding unwanted mass to the sample. Current applications in nuclear forensics call for an optimization of energy resolution and yield in order to improve identification and quantify specific radionuclides. The purpose of this research is to determine the optimal parameters used for microprecipitation. The optimal solution temperature, precipitation time, carrier amount, and hydrofluoric acid amount are used to investigate the influence of varying the type of carrier, as well as, the …

The Forensic Analysis Of Triacetone Triperoxide (Tatp) Precursors And Synthetic By-Products, Kimberly Painter

Electronic Theses and Dissertations

Triacetone Triperoxide (TATP) is a primary high explosive that can be synthesized using commercially available starting materials and has grown in use among terrorists over the past several years. Additives present in the precursors were investigated to see if they carry through the TATP synthesis and can be detected in the final product potentially aiding in the identification of the source. Additives identified in the acetones were also identified in pre-blast and in some post-blast samples. However, these additives are present in trace quantities relative to the TATP, which coupled with the volatility and short lifetimes of some of the …

A Photochemically Initiated Chemistry For Coupling Underivatized Carbohydrates To Gold Nanoparticles, Xin Wang, Olof Ramström, Mingdi Yan

Chemistry Faculty Publications and Presentations

The sensitive optoelectronic properties of metal nanoparticles make nanoparticle-based materials a powerful tool to study fundamental biorecognition processes. Here we present a new and versatile method for coupling underivatized carbohydrates to gold nanoparticles (Au NPs) via the photochemically induced reaction of perfluorophenylazide (PFPA). A one-pot procedure was developed where Au NPs were synthesized and functionalized with PFPA by a ligand-exchange reaction. Carbohydrates were subsequently immobilized on the NPs by a fast light activation. The coupling reaction was efficient, resulting in high coupling yield as well as high ligand surface coverage. A colorimetric system based on the carbohydrate-modified Au NPs was …

Synthesis Of Biocompatible Antioixidant Polymer Coated Cerium Oxide Nanoparticles, Its Oxidase Like Behavior And Cellular Uptake, Atul Asati

Electronic Theses and Dissertations

Cerium oxide nanoparticles have been widely used for various applications such as catalytic converters for automobile exhaust, ultraviolet absorber, and electrolyte in fuel cells. Most recently, cerium oxide nanoparticles (nanoceria) have been employed as potent free-radical scavengers with neuroprotective, radioprotective, and anti-inflammatory properties. These properties of cerium oxide nanoparticles can open new vistas in medicine and biotechnology. The present study utilizes the water-based-wet-chemical method to synthesize biocompatible,stable and highly monodisperse polymer coated cerium oxide nanoparticles. Polymer coated cerium oxide nanoparticles possess all the characteristics of the uncoated cerium oxide nanoparticles. These nanoparticles were found to be effective as pH-dependent antioxidant …

Molecular Interaction Between Perthiolated [Beta]-Cyclodextrin (Cd) And The Guests Molecules Adamantaneacetic Acid (Ad) And Ferroceneacetic Acid (Fc); And The Effect Of The Interaction On The Electron Transition Of Cd Anchored Particles, Ming Ning

Dissertations, Master's Theses and Master's Reports - Open

The molecular interactions between the host molecule, perthiolated beta-cyclodextrin (CD), and the guest molecules, adamantaneacetic acid (AD) and ferroceneacetic acid (FC), have been inestigated theoretically in both the gas and aqueous phases. The major computations have been carried out at the theoretical levels, RHF/6-31G and B3LYP/6- 31G. MP2 electronic energies were also computed based at the geometries optimized by both the RHF and B3LYP methods in the gas phase to establish a better estimate of the correlation effect.

The solvent phase computations were completed at the RHF/6-31G and B3LYP/6-31G levels using the PCM model. The most stable structures optimized in …

Synthesis, Characterization And Use Of Nb2 O5 Based Catalysts In Producing Biofuels By Transesterification, Esterification And Pyrolysis, Rodrigo F. Brandão, Rafael L. Quirino, Vinicius M. Mello, André P. Tavares, Antônio C. Peres, Flávia Guinhos, Joel C. Rubim, Paulo A. Z. Suarez

Chemistry: Faculty Publications (1990-2023)

Nb2O5/HX (X = HSO4-, H2PO4-, NO3-) compounds were obtained from the treatment of niobium acid (Nb2O5·xH2O) with sulfuric, phosphoric, and nitric acids as well as Nb2O5 and Nb2O5·xH2O have been investigated as catalysts for the transesterification, esterification and pyrolysis of vegetable oils. The compounds were characterized by thermal analysis (DTA-TGA), spectroscopy (DRX, FT-IR and FT-Raman), surface area (BET) and the acidity (Ho) determined by n-butylamine titration using the Hammet´s indicator method. It was observed that after the acid treatment both the surface area and the acidity decreased as compared to the starting Nb2O5·xH2O. The only exception was a higher acidity …

Investigation Of The Interactions Between Selected Nanoparticles And Human Lung Carcinoma Cells At The Single Cell And Single Particle Level, Isaac Stayton

Doctoral Dissertations

"The recent advances in nanomaterials development and applications have sparked concerns regarding the safety of these materials in living organisms. This body of work investigates specific interactions between chosen nanoparticles and living human lung carcinoma (A549) cells"--Abstract, page iv.

A Study Of The Beneficial Role Of Thiol Antioxidant Supplementation In Various Forms Of Glutathione Deficiency, Linu Sara Abraham

Doctoral Dissertations

"Oxidative stress plays a major role in the pathology of numerous disorders afflicting humans, ranging from neurodegenerative diseases, to cancer, and heavy metal toxicity. Scientists are on the constant lookout for new and better antioxidants that have the ability to slow, if not stop the harmful degenerative effects of free radicals in oxidative stress related disorders. Both synthetic and naturally occurring compounds are being constantly screened for their antioxidant properties. This study attempted to evaluate the abilities of a thiol antioxidant, N-Acetylcysteine amide (NACA), to protect cells from the harmful effects of glutathione depletion in two different models of oxidative …

F₂-Isoprostanes Study After Exposure To Selected Nanoparticles By Liquid Chromatography/Tandem Mass Spectrometry And Investigation Of Nanoparticles On The Cytotoxicity Effect Of Arsenic In Vitro, Xiaoqian Liu

Doctoral Dissertations

"Nanopartices as a new class of materials found their applications in industry, aerospace, clinical diagnosis and cancer therapy. Recently, the health effects of nanoparticles have caused people great concerns. This dissertation studies the mechanisms of nanoparticle cytotoxicity in human lung epithelial cells (A549). F₂-isoprostanes are novel reliable biomarkers for lipid peroxidation. In the first part of this work, total free F₂-isoprostanes were quantified by high performance liquid chromatography/mass spectrometry followed by the exposure of SiO₂ (15 nm), CeO₂ (20 nm), Fe₂O₃ (30 nm), and ZnO (70 nm) nanoparticles for 24 hours. For the first time, the results showed that F₂-isoprostanes …

Size Controlled Metal Oxide Nanoparticles:Synthesis, Characterization, And Application To Catalysis, Hongyi Wu

LSU Doctoral Dissertations

The research in this dissertation focuses on the synthesis of size-controlled metal oxide nanoclusters (< 10 nm) on amorphous silica and their catalytic performance in thermal degradation of chlorinated benzenes with regard to the cluster size effect. Furthermore, with the concern that metal can condense as the nano-size nuclei core for particle growth in combustion process, a flow reactor was built to investigate the effect of metal oxide nanoparticles on the formation of soot in fuel-rich combustion. The synthesis of copper oxide nanoclusters was carried by calcination of silica impregnated with dendrimer-metal complexes. The 4th generation poly(propylene imine) dendrimer DAB-Am32 was used in this template-based method. The sizes of copper oxide nanoclusters were exquisitely controlled in the range of 1-5 nm with narrow size distribution by changing the stoichiometric ratio of metal ion to the terminal primary amines of dendrimer, the equivalent metal oxide loading on surface, and the impregnation procedure. XANES and XPS studies revealed that CuO was the dominant component of copper oxide nanoclusters. This method was also experimentally proven to be valid in the preparation of other metal oxide nanoparticles, e.g., Ni and Fe, and with other oxide substrates, e.g., titanium oxide. Chlorinated benzenes were selected as the model compound for studying the activity of metal (Cu and Fe) oxide catalysts with regard to their cluster sizes. Compared to the surrogate of coarse metal oxide samples, which was prepared by incipient wetness method, their nanosize analogues showed superior catalytic activity on the conversion of chlorinated benzenes under both pyrolytic and oxidative thermal condition. Furthermore, such catalytic size effect was also observed on the selectivity of products yields. Sooting combustion was performed using a two-zone flow reactor with precise control on experimental parameters. Gas suspended metal oxide nanoparticles were generated by burning off the organic backbone of the dendrimer-metal complexes in zone 1 and immediately transferred to zone 2, where the hydrocarbon combustion occurred. TEM results of the particulate sample collected at the outlet of reactor indicated that metal oxide nanoparticles promoted soot formation. GC/MS analysis of the extracted organic materials from soot samples suggested the formation of PAH was also promoted by metal addition as well.

Highly Stereoselective B-Lactam Synthesis Via The Staudinger Reaction Using Poly Aromatic Imines, Debasish Bandyopadhyay, Monica Xavier, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Highly stereoselective synthesis of a few trans 3-phthalimido substituted B-lactams has been achieved following Staudinger reaction.

Imide-Functionalized Conjugated Polymers: Synthesis, Structure-Property And Device Studies, Xugang Guo

University of Kentucky Doctoral Dissertations

Organic semiconductors are widely studied as potential active components for consumer electronics due largely to their easily tuned properties and the promise of lower-cost solution-based processing technology. Imide-functionalized organic small molecule compounds have been one of the more important and studied organic semiconductors. However, very few imide-functionalized conjugated polymers have been reported in the literature. The body of this dissertation focuses on the synthesis, structure-property and device studies of imide-functionalized conjugated polymers. Reasons for choosing arylene imides as polymer building blocks include: a) they impart low-lying LUMOs to polymers, allowing band-gap engineering through choice of comonomers with variable electron-donating ability; …

Preliminary Development Of Quantitative Immunoassays For Mitochondrial Proteins, Adriann Hovey

Honors Program Theses

Mitochondria are medium-sized organelles in which most cellular metabolic reactions are carried out. In postmitotic cells that are aged or diseased, such as myocardial, skeletal, and brain cells, abnormally large mitochondria ("giant mitochondria") are often observed. Mitochondrial size and shape are controlled by mitochondrial fusion and fission and disruption of this process may lead to their abnormally large size (Nauratil, Terman, Arriaga, 2008). These giant mitochondria exhibit variations from normal metabolism and altered membrane potentials (Nauratil et al., 2008). An increased number of giant mitochondria may therefore disrupt cell function (Nauratil et al., 2008). This accumulation may result either from …

Raman Spectroscopy Of Biological Molecules And Inorganic Compounds, Jasmine Gardner

Theses and Dissertations

This dissertation describes the use of multiple Raman spectroscopic techniques for the detection and characterization of non-hazardous organic and inorganic compounds. The first two applications involve the use of Raman and surface enhanced Raman spectroscopy to thoroughly analyze autoinducers (AI) produced by gram negative bacteria. The second set of applications involves the use of anti-Stokes Raman and resonance Raman spectroscopy to remotely detect inorganic compounds at distances of up to 12 meters away.

Chapters two and three describe the use of Raman spectroscopy for the characterization and discrimination of signaling molecules used in bacterial communication. Our initial work shows the …

Substrate Induced Structural And Dynamics Changes In Human Phosphomevalonate Iinase And Implications For Mechanism, Andrew Lawrence Olson, Huili Yao, Timothy J. Herdendorf, Henry M. Miziorko, Supa Hannongbua, Patchareenat Saparpakom, Sheng Cai, Daniel S. Sem

Chemistry Faculty Research and Publications

Phosphomevalonate kinase (PMK) catalyzes an essential step in the mevalonate pathway, which is the only pathway for synthesis of isoprenoids and steroids in humans. PMK catalyzes transfer of the γ-phosphate of ATP to mevalonate 5-phosphate (M5P) to form mevalonate 5-diphosphate. Bringing these phosphate groups in proximity to react is especially challenging, given the high negative charge density on the four phosphate groups in the active site. As such, conformational and dynamics changes needed to form the Michaelis complex are of mechanistic interest. Herein, we report the characterization of substrate induced changes (Mg-ADP, M5P, and the ternary complex) in PMK using …

Anthropogenic Osmium In Rain And Snow Reveals Global-Scale Atmospheric Contamination, Cynthia Chen, Peter N. Sedwick, Mukul Sharma

OES Faculty Publications

Osmium is one of the rarer elements in seawater, with typical concentration of ≈10 x 10^-15 g g^-1 ( 5.3 x 10^-14 mol kg^-1. The osmium isotope composition (¹⁸⁷Os/¹⁸⁸Os ratio) of deep oceans is 1.05, reflecting a balance between inputs from continental crust (≈ 1.3) and mantle/cosmic dust (≈ 0.13). Here, we show that the ¹⁸⁷Os/¹⁸⁸Os ratios measured in rain and snow collected around the world range from 0.16 to 0.48, much lower than expected (>1), but similar to the isotope composition of ores (approximate to 0.2) …

Mutation Of H63 And Its Catalytic Affect On The Methionine Aminopeptidase From Escherichia Coli, Sanghamitra Mitra, Brian Bennett, Richard C. Holz

Chemistry Faculty Research and Publications

In order to gain insight into the mechanistic role of a flexible exterior loop near the active site, made up of Y62, H63, G64, and Y65, that has been proposed to play an important role in substrate binding and recognition in the methionyl aminopeptidase from Escherichia coli (EcMetAP-I), the H63A enzyme was prepared. Mutation of H63 to alanine does not affect the ability of the enzyme to bind divalent metal ions. The specific activity of H63A EcMetAP-I was determined using four different substrates of varying lengths, namely, l-Met-p-NA, MAS, MGMM and MSSHRWDW. For the smallest/shortest …

Noncovalent Interaction Of Platinum Planar Amine Compounds With Tryptophan: A Strategy To Interfere With P53-Mdm2 Interactions And Targeting Retroviral Zn Finger-Dna Interaction (Hiv Ncp7), Aaron Bate

Theses and Dissertations

Non-covalent interactions involving π-π stacking play an essential role in self-assembly and molecular recognition processes such as protein folding and DNA/RNA-protein selective recognition. The knowledge gained from these studies could provide insight into possible site recognition complexes, inhibiting or mimicking protein-protein or protein-DNA interactions. Based on molecular modeling as well as HOMO and LUMO energies, several chromophores were selected with a variety of ∆ε values (∆ε= |εHOMO,NAcTrp – εLUMO,chromophores|), high and low, to establish a correlating trend with the modeling and experimental data. The corresponding Pt(dien) compounds were synthesized and their ability to stack to N-acetyl tryptophan was evaluated by …

Molecular Motion And Performance Enhancement Of Borazan Fluorescent Dyes, Tyler James Morin, Sergey V. Lindeman, James R. Gardinier

Chemistry Faculty Research and Publications

The preparation of three 2,6-dipyrazolyl-4-X-anilines, H(pz₂An^X) (X = p-CF₃, Cl, tBu) using CuI-catalyzed amination is described. Subsequent reactions of H(pz₂An^X) with triphenylboron proceeds with benzene elimination to give the corresponding Ph₂B(pz₂An^X) compounds in high yields. The Ph₂B(pz₂An^X) are more highly emissive in the solid state than the previously reported BORAZAN fluorophores, Ph₂B(pzAn^X), their monopyrazolyl counterparts. As with the Ph₂B(pzAn^X), the color of emission in Ph₂B(pz_{2 …}

Carbon−Phosphorus Bond Activation Of Tri(2-Thienyl)Phosphine At Dirhenium And Dimanganese Centers, Md. Nazim Uddin, M. Abdul Mottalib, Noorjahan Begum, Shishir Ghosh, Arun K. Raha, Daniel T. Haworth, Sergey V. Lindeman, Tasneem Siddiquee, Dennis W. Bennett, Graeme Hogarth, Ebbe Nordlander, Shariff E. Kabir

Chemistry Faculty Research and Publications

Reaction of [Re₂(CO)₉(NCMe)] with tri(2-thienyl)phosphine (PTh₃) in refluxing cyclohexane affords three substituted dirhenium complexes: [Re₂(CO)₉(PTh₃)] (1), [Re₂(CO)₈(NCMe)(PTh₃)] (2), and [Re₂(CO)₈(PTh₃)₂] (3). Complex 2 was also obtained from the room-temperature reaction of [Re₂(CO)₈(NCMe)₂] with PTh₃ and is an unusual example in which the acetonitrile and phosphine ligands are coordinated to the same rhenium atom. Thermolysis of 1 and 3 in refluxing xylene …

Octamethoxydibenzochrysene: Isolation And X-Ray Crystallographic Characterization Of A Twisted Polyaromatic Cation Radical, Tushar Navale, Linyi Zhai, Sergey V. Lindeman, Rajendra Rathore

Chemistry Faculty Research and Publications

The isolation and X-ray crystal structure determination of octamethoxydibenzochrysene (3) cation radical together with DFT calculations allow us to delineate evidence that the complex structural changes (i.e. elongation and shortening of various bonds) in a polyaromatic hydrocarbon can be predicted based on the positioning of the largest bonding and antibonding character of the HOMO.

Terphenyl Crowns: A New Family Of Receptors Containing Ethereal Canopies That Direct Potassium Cation Onto Benzenoid Platforms For Cation–Π Interactions, Ruchi Shukla, Sergey V. Lindeman, Rajendra Rathore

Chemistry Faculty Research and Publications

We have synthesized three simple and versatile terphenyl crowns (TC) receptors containing ethereal canopies that direct a potassium cation for efficient cation–π interactions as established by ¹H NMR spectroscopy and by isolation and X-ray crystallography of their K⁺ salts.

13c-Methyl Isocyanide As An Nmr Probe For Cytochrome P450 Active Site, Christopher R Mccullough, Phani Kumar Pullela, Sang-Choul Im, Lucy Waskell, Daniel S. Sem

Chemistry Faculty Research and Publications

The cytochromes P450 (CYPs) play a central role in many biologically important oxidation reactions, including the metabolism of drugs and other xenobiotic compounds. Because they are often assayed as both drug targets and anti-targets, any tools that provide: (a) confirmation of active site binding and (b) structural data, would be of great utility, especially if data could be obtained in reasonably high throughput. To this end, we have developed an analog of the promiscuous heme ligand, cyanide,with a ¹³CH₃-reporter attached. This ¹³C-methyl isocyanide ligand binds to bacterial (P450cam) and membrane-bound mammalian (CYP2B4) CYPs. It can be …

A Versatile Preparation Of Geländer-Type P-Terphenyls From A Readily Available Diacetylenic Precursor, Matthew J. Modjewski, Sergey V. Lindeman, Rajendra Rathore

Chemistry Faculty Research and Publications

A series of doubly bridged p-terphenyls (4) have been synthesized utilizing a facile three-step synthesis starting from the readily available diacetylenic precursor (1) in excellent overall yields, and their structures were confirmed by 1H/13C NMR spectroscopy as well as by X-ray crystallography. The racemization barrier between the meso and chiral atropisomers of one of the derivatives of 4 was found to be ∼12 kcal/mol by variable-temperature NMR spectroscopy. The versatility of the protocol developed herein was further demonstrated by the preparation of a quadruply bridged penta-p-phenylene derivative.

Tetranuclear Group 7/8 Mixed-Metal And Open Trinuclear Group 7 Metal Carbonyl Clusters Bearing Bridging 2-Mercapto-1-Methylimidazole Ligands, Shishir Ghosh, Shariff E. Kabir, Salina Pervin, Arun K. Raha, G. M. Golzar Hossain, Daniel T. Haworth, Sergey V. Lindeman, Dennis W. Bennett, Tasneem Siddiquee, Luca Salassa, Herbert W. Roesky

Chemistry Faculty Research and Publications

The reactivity of group 7 metal dinuclear carbonyl complexes [M₂(CO)₆(μ-SN₂C₄H₅)₂] (1, M = Re; 2, M = Mn) toward group 8 metal trinuclear carbonyl clusters were examined. Reactions of 1 and 2 with [Os₃(CO)₁₀(NCMe)₂] in refluxing benzene furnished the tetranuclear mixed-metal clusters [Os₃Re(CO)₁₃(μ₃-SN₂C₄H₅)] (3) and [Os₃Mn(CO)₁₃(μ₃-SN₂C₄H₅)] (4), respectively. Similar treatment of …

Molecular Actuator: Redox-Controlled Clam-Like Motion In A Bichromophoric Electron Donor, Vincent J. Chebny, Ruchi Shukla, Sergey V. Lindeman, Rajendra Rathore

Chemistry Faculty Research and Publications

The one-electron oxidation of tetramethoxydibenzobicyclo[4.4.1]undecane (4) prompts it to undergo a clam-like electromechanical actuation into a cofacially π-stacked conformer as established by (i) electrochemical analysis, (ii) by the observation of the intense charge-resonance transition in the near IR region in its cation radical spectrum, and (iii) by X-ray crystallographic characterization of the isolated cation radical salt (4^+• SbCl₆⁻).