Physical Sciences and Mathematics Commons^™

Fluorination Of Aromatic Ring Systems, Stephen G. Dimagno

Chemistry Department: Faculty Publications

This disclosure relates to reagents and methods useful in the synthesis of aryl fluorides, for example, in the preparation of ¹⁸F labeled radiotracers. The reagents and methods provided herein may be used to access a broad range of compounds, including aromatic compounds, heteroaromatic compounds, amino acids, nucleotides, and synthetic compounds.

Phosphate Esters, Thiophosphate Esters And Metal Thiophosphates As Lubricant Additives, David W. Johnson, John E. Hils

Chemistry Faculty Publications

Phosphate esters, thiophosphate esters and metal thiophosphates have been used as lubricant additives for over 50 years. While their use has been extensive, a detailed knowledge of how they work has been a much more recent development. In this paper, the use of phosphate esters and thiophosphate esters as anti-wear or extreme pressure additives is reviewed with an emphasis on their mechanism of action. The review includes the use of alkyl phosphates, triaryl phosphates and metal containing thiophosphate esters. The mechanisms of these materials interacting with a range of iron and steel based bearing material are examined.

The Development And Applications Of Nmr Metabolomics Analysis Of Bacterial Metabolomes, Steven M. Halouska

Department of Chemistry: Dissertations, Theses, and Student Research

Metabolomics is a relatively new field that involves the study of metabolic responses that are occurring within a biological system. Metabolite profiles of an organism, tissue extract, and biofluids are important indicators to determine the physiological state of a biological profile. Comparison of such profiles from different phenotypes can be used to identify specific metabolic changes leading to the understanding of metabolic pathways, disease progression, drug toxicity and efficacy, and cellular responses to different intracellular and extracellular conditions. Metabolomics investigations often use sophisticated analytical techniques such as NMR spectroscopy to provide an unbiased and comprehensive approach to evaluate metabolic perturbation …

Synthesis And Structures Of New Three-Dimensional Copper Metal-Organic Frameworks, Nitin Kumar Pally

Masters Theses & Specialist Projects

Metal-organic frameworks (MOFs) are crystalline materials with metal ions covalently bonded to organic ligands. The ligands act as spacers often creating a porous structure with very high pore volume and surface area. MOFs are known for their robust structures, high porosity, and different chemical functionalities and are considered for applications in adsorptions, separations, catalysis and gas storage. This work focuses on the synthesis of new MOFs using copper compounds. Different types of carboxylate ligands were used for the synthesis. Two new copper-organic frameworks, [Cu₃(pyz)(btc)] (1), and [(Cu₃(btc))•xH₂O] (2) (btc= benzene-1,3,5-tricarboxylate, pyz= pyrazine) have been …

Synthesis And Characterization Of Manganese Pyridazyl Complexes, Sana Shah

Masters Theses & Specialist Projects

Heterocyclic’s and their fused-ring derivatives have been of interest for their use in electronic materials due to their ease of production, synthetic versatility, and low cost compared to traditional inorganic materials like silicon. Pyridazines have been found to be useful in catalysis gas storage, polymeric sensors and biological mimetics. When a transition-metal is fused into a synthesized pyridazine, unique properties such as conductivity and optics are allowed. In this work, synthesized pyridazine complexes will be analyzed by mass spectroscopy, elemental analysis, nuclear magnetic resonance, imaging, x-ray crystallography, and infrared spectroscopy. We are interested in synthesizing organometallic pyridazines and manganese pyridazyl …

Improved Dynamic Headspace Sampling And Detection Using Capillary Microextraction Of Volatiles Coupled To Gas Chromatography Mass Spectrometry, Wen Fan

FIU Electronic Theses and Dissertations

Sampling and preconcentration techniques play a critical role in headspace analysis in analytical chemistry. My dissertation presents a novel sampling design, capillary microextraction of volatiles (CMV), that improves the preconcentration of volatiles and semivolatiles in a headspace with high throughput, near quantitative analysis, high recovery and unambiguous identification of compounds when coupled to mass spectrometry. The CMV devices use sol-gel polydimethylsiloxane (PDMS) coated microglass fibers as the sampling/preconcentration sorbent when these fibers are stacked into open-ended capillary tubes. The design allows for dynamic headspace sampling by connecting the device to a hand-held vacuum pump. The inexpensive device can be fitted …

Rapid Inline Derivatization Of Primary And Secondary Amine Containing Drugs By Capillary Electrophoresis With Laser-Induced Fluorescence, Britt E. Turnquest

FIU Electronic Theses and Dissertations

Despite the ongoing “war on drugs” the seizure rates for phenethylamines and their analogues have been steadily increasing over the years. The illicit manufacture of these compounds has become big business all over the world making it all the more attractive to the inexperienced “cook”. However, as a result, the samples produced are more susceptible to contamination with reactionary byproducts and leftover reagents. These impurities are useful in the analysis of seized drugs as their identities can help to determine the synthetic pathway used to make these drugs and thus, the provenance of these analytes. In the present work two …

Elemental Analysis And Forensic Comparison Of Soils By Laser-Induced Breakdown Spectroscopy (Libs) And Laser Ablation Inductively Coupled Plasma Mass Spectrometry (La-Icp-Ms), Sarah C. Jantzi

FIU Electronic Theses and Dissertations

The elemental analysis of soil is useful in forensic and environmental sciences. Methods were developed and optimized for two laser-based multi-element analysis techniques: laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and laser-induced breakdown spectroscopy (LIBS). This work represents the first use of a 266 nm laser for forensic soil analysis by LIBS.

Sample preparation methods were developed and optimized for a variety of sample types, including pellets for large bulk soil specimens (470 mg) and sediment-laden filters (47 mg), and tape-mounting for small transfer evidence specimens (10 mg). Analytical performance for sediment filter pellets and tape-mounted soils was similar …

Method Development For The Analysis Of Smokeless Powders And Organic Gunshot Residue By Ultra Performance Liquid Chromatography With Tandem Mass Spectrometry, Jennifer L. Thomas

FIU Electronic Theses and Dissertations

The goal of this project was to develop a rapid separation and detection method for analyzing organic compounds in smokeless powders and then test its applicability on gunshot residue (GSR) samples. In this project, a total of 20 common smokeless powder additives and their decomposition products were separated by ultra performance liquid chromatography (UPLC) and confirmed by tandem mass spectrometry (MS/MS) using multiple reaction monitoring mode (MRM). Some of the targeted compounds included diphenylamines, centralites, nitrotoluenes, nitroglycerin, and various phthalates. The compounds were ionized in the MS source using simultaneous positive and negative electrospray ionization (ESI) with negative atmospheric pressure …

Evaluation Of Non-Contact Sampling And Detection Of Explosives Using Receiver Operating Characteristic Curves, Mimy Young

FIU Electronic Theses and Dissertations

The growing need for fast sampling of explosives in high throughput areas has increased the demand for improved technology for the trace detection of illicit compounds. Detection of the volatiles associated with the presence of the illicit compounds offer a different approach for sensitive trace detection of these compounds without increasing the false positive alarm rate. This study evaluated the performance of non-contact sampling and detection systems using statistical analysis through the construction of Receiver Operating Characteristic (ROC) curves in real-world scenarios for the detection of volatiles in the headspace of smokeless powder, used as the model system for generalizing …

The Utilization Of Chiral Ion Mobility Spectrometry For The Detection Of Enantiomeric Mixtures And Thermally Labile Compounds, Howard K. Holness

FIU Electronic Theses and Dissertations

This dissertation utilized electrospray ion mobility mass spectrometry (ESI-IMS-MS) to develop methods necessary for the separation of chiral compounds of forensic interest. The compounds separated included ephedrines and pseudoephedrines, that occur as impurities in confiscated amphetamine type substances (ATS) in an effort to determine the origin of these substances. The ESI-IMS-MS technique proved to be faster and more cost effective than traditional chromatographic methods currently used to conduct chiral separations such as gas and liquid chromatography. Both mass spectrometric and computational analysis revealed the separation mechanism of these chiral interactions allowing for further development to separate other chiral compounds by …

Comprehensive Forensic Toxicological Analysis Of Designer Drugs, Madeleine Jean Swortwood

FIU Electronic Theses and Dissertations

New designer drugs are constantly emerging onto the illicit drug market and it is often difficult to validate and maintain comprehensive analytical methods for accurate detection of these compounds. Generally, toxicology laboratories utilize a screening method, such as immunoassay, for the presumptive identification of drugs of abuse. When a positive result occurs, confirmatory methods, such as gas chromatography (GC) or liquid chromatography (LC) coupled with mass spectrometry (MS), are required for more sensitive and specific analyses. In recent years, the need to study the activities of these compounds in screening assays as well as to develop confirmatory techniques to detect …

Conversion Of Iodide To Hypoiodous Acid And Iodine In Aqueous Microdroplets Exposed To Ozone, Elizabeth A. Pillar, Marcelo I. Guzman, Jose M. Rodriguez

Chemistry Faculty Publications

Halides are incorporated into aerosol sea spray, where they start the catalytic destruction of ozone (O₃) over the oceans and affect the global troposphere. Two intriguing environmental problems undergoing continuous research are (1) to understand how reactive gas phase molecular halogens are directly produced from inorganic halides exposed to O₃ and (2) to constrain the environmental factors that control this interfacial process. This paper presents a laboratory study of the reaction of O₃ at variable iodide (I^–) concentration (0.010–100 μM) for solutions aerosolized at 25 °C, which reveal remarkable differences in the reaction intermediates …

Structure, Theoretical Studies And Coupling Reactions Of Some New Cyclic Boronic Esters, Andrew Kuttler, Sravanthi Durganala, Albert Fratini, Alexander Morgan, Vladimir Benin

Chemistry Faculty Publications

The present report describes the X-ray structural and theoretical studies of some new pinacolboronate esters, and it also outlines the use of the target structures in Suzuki coupling reactions to produce new aromatic or heteroaromatic esters and amides. X-ray structural analysis of the studied compounds revealed that the pinacolborane ring's position with respect to the benzene ring varies, depending on the particular environment. An ortho-positioned carboxylic ester (methyl ester) causes a nearly perpendicular orientation of the pinacolborane unit with respect to the benzene ring, whereas an ortho-positioned amide (N,N-dimethylamide) causes the pinacolborane unit to orient itself nearly coplanar. A plausible …

Io3- And I- Sorption From Groundwater By Layered Double Hydroxides, Abbey Rickelmann, Emily Campbell, Natasha Pence, Tatiana Levitskaia, Sayandev Chatterjee, Frances Smith

STAR Program Research Presentations

Several subsurface water plumes are found at the Hanford U.S. DOE site. These plumes contain many different types of hazardous components including radioactive iodate (IO₃^-) and iodide (I^-), which may have deleterious health effects. To selectively uptake IO₃^- and I^-, inorganic layered double hydroxide (LDH) compounds were synthesized and tested. LDHs are mixed transition metal hydroxides that contain positively charged layers that undergo anion exchange. When LDHs are submerged in the plume water, they can selectively uptake IO₃^- and I^- and remove them from the plume. Raman spectroscopy …

Development Of Colloid Displacement Lithography Platforms For Sensor Applications, Mahesh Thugu

Masters Theses & Specialist Projects

In this work, Poly (diallyldimethylammonium) chloride - (PDDA) was used as a base layer for developing colloid displacement lithography platforms for sensor applications. Previous work shows that glass coated with PDDA and exposed to gold acts as a good platform for colloid displacement lithography. However, for actual sensor applications, electrical isolation of individual sensor sections must be achieved. This is attempted by laying down a 40 μm stripe of PDDA on a cleaned substrate and coating that stripe with gold colloid. The size of 40 μm or less in width is set as the target to fit within the scan …

Reinventing Aromatic Substitution: A Novel Look, Quang Nguyen

Masters Theses & Specialist Projects

Electrophilic aromatic substitution (EAS) and directed ortho-metalation (DoM) involve the direct substitution of an arene hydrogen. A major drawback involving EAS is the necessity for harsh forcing conditions for the reaction to proceed. Catalysts such as Lewis acids FeBr₃ and AICI₃ for the introduction of halogens and acyl groups, respectively, are each highly toxic and corrosive. Textbook preparations of aryl iodides classicaly involved the use of iodine and nitric acid. This approach affords only modest yields and does not provide regiospecific substitution of most substituted aromatics because most contain ortho/para directors which afford mixtures of …

Assessment Of The Occurrence And Potential Risks Of Antibiotics And Their Metabolites In South Florida Waters Using Liquid Chromatography Tandem Mass Spectrometry, Venkata Reddy Panditi

FIU Electronic Theses and Dissertations

An automated on-line SPE-LC-MS/MS method was developed for the quantitation of multiple classes of antibiotics in environmental waters. High sensitivity in the low ng/L range was accomplished by using large volume injections with 10-mL of sample. Positive confirmation of analytes was achieved using two selected reaction monitoring (SRM) transitions per antibiotic and quantitation was performed using an internal standard approach. Samples were extracted using online solid phase extraction, then using column switching technique; extracted samples were immediately passed through liquid chromatography and analyzed by tandem mass spectrometry. The total run time per each sample was 20 min. The statistically calculated …

Characterization By Nmr Of Reactants And Products Of Hydrofluoroether Isomers, Cf3(Cf2)3och3 And (Cf3)2c(F)Cf2och3, Reacting With Isopropyl Alcohol, Howard Knachel, Vladimir Benin, William E. Moddeman, Janine C. Birkbeck, Thomas A. Kestner, Tayna L. Young

Chemistry Faculty Publications

The 3M Company product Novec™ 71IPA DL, a mixture of methoxyperfluorobutane, methoxyperfluoroisobutane and 4.5 wt.% isopropyl alcohol, has been found to be very stable at ambient temperature, producing fluoride at the rate of ~1 ppm/year. Our earlier kinetic and theoretical studies have identified the reaction mechanism. This paper identifies the ¹H and ¹⁹F NMR chemical shifts, multiplicities, and coupling constants of reactants and the major products that result from aging the mixture in sealed Pyrex NMR tubes for periods up to 1.8 years at temperatures from 26 °C to 102 °C. Chemical shifts and coupling constants of fluorine …

Effect Of Leaving Ligands Of Platinum(Ii) Diamine Complexes On Dna And Protein Residues, Ramya Kolli

Masters Theses & Specialist Projects

Platinum compounds are widely used drugs in cancer treatments. Although DNA is the biological target, reaction of platinum compounds with proteins is also potentially significant. Our objective is to study the effects of leaving ligands on the relative reactivity between 5'-GMP (guanosine 5' phosphate), a key DNA target, and N-Acetyl - L-Methionine (N-AcMet), a key protein target. We have used NMR spectroscopy to monitor reactions with N-AcMet and 5'-GMP added to a platinum complex to see which products are formed preferentially. Previous research showed that both a non-bulky complex such as [Pt(en)(D₂O)₂]²⁺ [en=ethylenediamine], and a …

Interaction Between Lubricants Containing Phosphate Ester Additives And Stainless Steels, David W. Johnson, Matthew Bachus, John E. Hils

Chemistry Faculty Publications

One way to improve fuel efficiency in today’s jet aircraft engines is to create an environment for higher operating temperatures and speeds. New and improved lubricants and bearing materials must be developed to remain stable in these elevated operating temperatures. Three lubricants, with varying amounts of tricresyl phosphate added as an anti-wear/extreme pressure additive were tested on two different stainless steels at varying temperatures ranging from 300 °C to 350 °C in vacuum. Significant decomposition of the lubricant base-stocks and the phosphate ester additive did occur in most of the trials resulting in the formation of carboxylic acids and phenols. …

Reliable Peak Selection For Multisample Analysis With Comprehensive Two-Dimensional Chromatography, Stephen E. Reichenbach, Xue Tian, Akwasi A. Boateng, Charles A. Mullen, Chiara Cordero, Qingping Tao

School of Computing: Faculty Publications

Comprehensive two-dimensional chromatography is a powerful technology for analyzing the patterns of constituent compounds in complex samples, but matching chromatographic features for comparative analysis across large sample sets is difficult. Various methods have been described for pairwise peak matching between two chromatograms, but the peaks indicated by these pairwise matches commonly are incomplete or inconsistent across many chromatograms. This paper describes a new, automated method for postprocessing the results of pairwise peak matching to address incomplete and inconsistent peak matches and thereby select chromatographic peaks that reliably correspond across many chromatograms. Reliably corresponding peaks can be used both for directly …

Photo Degradation Of Cotnaminants Of Emerging Concern (Cecs) Under Simulated Solar Radiation: Implications For Their Environmental Fate, Sudha Rani Batchu

FIU Electronic Theses and Dissertations

Contaminants of emerging concern (CECs) are continuously being released into the environment mainly because of their incomplete removal in the sewage treatment plants (STPs). The CECs selected for the study include antibiotics (macrolides, sulfonamides and ciprofloxacin), sucralose (an artificial sweetener) and dioctyl sulfosuccinate (DOSS, chemical dispersant used in the Deepwater Horizon oil spill). After being discharged into waterways from STPs, photo degradation is a key factor in dictating the environmental fate of antibiotics and sucralose. Photodegradation efficiency depends on many factors such as pH of the matrix, matrix composition, light source and structure of the molecule. These factors exert either …

The Effect Of Iron Oxide Nanoparticles On The Fate And Transformation Of Arsenic In Aquatic Environments, Dionne Dickson

FIU Electronic Theses and Dissertations

Iron oxides and arsenic are prevalent in the environment. With the increase interest in the use of iron oxide nanoparticles (IONPs) for contaminant remediation and the high toxicity of arsenic, it is crucial that we evaluate the interactions between IONPs and arsenic. The goal was to understand the environmental behavior of IONPs in regards to their particle size, aggregation and stability, and to determine how this behavior influences IONPs-arsenic interactions.

A variety of dispersion techniques were investigated to disperse bare commercial IONPs. Vortex was able to disperse commercial hematite nanoparticles into unstable dispersions with particles in the micrometer size range …

Monolayer-Protected Nanoparticle Doped Xerogels As Functional Components Of Amperometric Glucose Biosensors, Michael Hartley Freeman, Jackson R. Hall, Michael C. Leopold

Chemistry Faculty Publications

First-generation amperometric glucose biosensors incorporating alkanethiolate-protected gold nanoparticles, monolayer protected clusters (MPCs), within a xerogel matrix are investigated as model systems for nanomaterial-assisted electrochemical sensing strategies. The xerogel biosensors are comprised of platinum electrodes modified with composite films of (3-mercaptopropyl)trimethoxy silane xerogel embedded with glucose oxidase enzyme, doped with Au225(C6)75 MPCs, and coated with an outer polyurethane layer. Electrochemistry and scanning/transmission electron microscopy, including cross-sectional TEM, show sensor construction, humidity effects on xerogel structure, and successful incorporation of MPCs. Analytical performance of the biosensor scheme with and without MPC doping of the xerogel is determined from direct glucose injection during …

Comprehensive Analysis Of Escape-Cone Losses From Luminescent Waveguides, Stephen R. Mcdowall, Tristan Butler, Edward Bain, Kelsey Scharnhorst, David L. Patrick

Mathematics Faculty Publications

Luminescent waveguides (LWs) occur in a wide range of applications, from solar concentrators to doped fiber amplifiers. Here we report a comprehensive analysis of escape-cone losses in LWs, which are losses associated with internal rays making an angle less than the critical angle with a waveguide surface. For applications such as luminescent solar concentrators, escape-cone losses often dominate all others. A statistical treatment of escape-cone losses is given accounting for photoselection, photon polarization, and the Fresnel relations, and the model is used to analyze light absorption and propagation in waveguides with isotropic and orientationally aligned luminophores. The results are then …

Utilizing Nmr Spectroscopy And Molecular Docking As Tools For The Structural Determination And Functional Annotation Of Proteins, Jaime Stark

Department of Chemistry: Dissertations, Theses, and Student Research

With the completion of the Human Genome Project in 2001 and the subsequent explosion of organisms with sequenced genomes, we are now aware of nearly 28 million proteins. Determining the role of each of these proteins is essential to our understanding of biology and the development of medical advances. Unfortunately, the experimental approaches to determine protein function are too slow to investigate every protein. Bioinformatics approaches, such as sequence and structure homology, have helped to annotate the functions of many similar proteins. However, despite these computational approaches, approximately 40% of proteins still have no known function. Alleviating this deficit will …

How Much Arsenic Do We Eat?, Julian Tyson

Science and Engineering Saturday Seminars

No abstract provided.

Dispersive Liquid–Liquid Microextraction And Microsample Injection System Coupled With Inductively Coupled Plasma-Mass Spectrometry For Inorganic Arsenic Speciation In Natural Waters, Latif Elci, Aydan Elci, Tiffany Berg, Julian Tyson

Chemistry Department Faculty Publication Series

No abstract provided.

Probing The Bifunctional Catalytic Activity Of Ceria Nanorods Towards The Cyanosilylation Reaction, Gonghua Wang, Lu Wang, Xiang Fei, Yunyun Zhou, Renat F. Sabirianov, Wai-Ning Mei, Chin Li Cheung

Chemistry Department: Faculty Publications

Ceria nanorods were demonstrated to be an active, bifunctional catalyst for the cyanosilylation of aldehydes. The catalytic activity of ceria was shown to be positively correlated with a decrease in the coordination numbers of neighbouring oxygen atoms around cerium atoms in the catalyst. Chemisorption and density functional theory studies suggested that the coordinatively unsaturated cerium sites exposed by the surface oxygen vacancy defects functioned as Lewis acid sites and the neighbouring oxygen atoms behaved as Lewis base sites in the catalytic cycle.