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Full-Text Articles in Chemistry

A Computational Approach For Mapping Electrochemical Activity Of Multi-Principal Element Alloys, Jodie A. Yuwono, Xinyu Li, Tyler D. Dolezal, Adib J. Samin, Javen Qinfeng Shi, Zhipeng Li, Nick Birbilis Nov 2023

A Computational Approach For Mapping Electrochemical Activity Of Multi-Principal Element Alloys, Jodie A. Yuwono, Xinyu Li, Tyler D. Dolezal, Adib J. Samin, Javen Qinfeng Shi, Zhipeng Li, Nick Birbilis

Faculty Publications

Multi principal element alloys (MPEAs) comprise an atypical class of metal alloys. MPEAs have been demonstrated to possess several exceptional properties, including, as most relevant to the present study a high corrosion resistance. In the context of MPEA design, the vast number of potential alloying elements and the staggering number of elemental combinations favours a computational alloy design approach. In order to computationally assess the prospective corrosion performance of MPEA, an approach was developed in this study. A density functional theory (DFT) – based Monte Carlo method was used for the development of MPEA ‘structure’; with the AlCrTiV alloy used …


The Emerging Applications Of Sulfur (Vi) Fluorides In Catalysis, Nicholas Ball, Cayo Lee, Jonathan E. Elisabeth, Nathan C. Friede, Glenn M. Sammis May 2021

The Emerging Applications Of Sulfur (Vi) Fluorides In Catalysis, Nicholas Ball, Cayo Lee, Jonathan E. Elisabeth, Nathan C. Friede, Glenn M. Sammis

Pomona Faculty Publications and Research

The past decade has witnessed remarkable growth of catalytic transformations in organic sulfur(VI) fluoride chemistry. This Perspective concentrates exclusively on foundational examples that utilize catalytic strategies to synthesize and react S(VI) fluorides. Key mechanistic studies that aim to provide insight toward future catalytic systems are emphasized.


Alternative View Of Oxygen Reduction On Porous Carbon Electrocatalysts: The Substance Of Complex Oxygen-Surface Interactions, Giacomo De Falco, Marc Florent, Jacek Jagiello, Yongqiang Cheng, Luke L. Daemen, Anibal J. Ramirez-Cuesta, Teresa J. Bandosz Mar 2021

Alternative View Of Oxygen Reduction On Porous Carbon Electrocatalysts: The Substance Of Complex Oxygen-Surface Interactions, Giacomo De Falco, Marc Florent, Jacek Jagiello, Yongqiang Cheng, Luke L. Daemen, Anibal J. Ramirez-Cuesta, Teresa J. Bandosz

Publications and Research

Electrochemical oxygen reduction reaction (ORR) is an important energy-related process requiring alternative catalysts to expensive platinum-based ones. Although recently some advancements in carbon catalysts have been reported, there is still a lack of understanding which surface features might enhance their efficiency for ORR. Through a detailed study of oxygen adsorption on carbon molecular sieves and using inelastic neutron scattering, we demonstrated here that the extent of oxygen adsorption/interactions with surface is an important parameter affecting ORR. It was found that both the strength of O2 physical adsorption in small pores and its specific interactions with surface ether functionalities in the …


Potential Application Of Ionic Liquids For Electrodeposition Of The Material Targets For Production Of Diagnostic Radioisotopes, Maciej Chotkowski, Damian Połomski, Kenneth Czerwinski Nov 2020

Potential Application Of Ionic Liquids For Electrodeposition Of The Material Targets For Production Of Diagnostic Radioisotopes, Maciej Chotkowski, Damian Połomski, Kenneth Czerwinski

Chemistry and Biochemistry Faculty Research

An overview of the reported electrochemistry studies on the chemistry of the element for targets for isotope production in ionic liquids (ILs) is provided. The majority of investigations have been dedicated to two aspects of the reactive element chemistry. The first part of this review presents description of the cyclotron targets properties, especially physicochemical characterization of irradiated elements. The second part is devoted to description of the electrodeposition procedures leading to obtain elements or their alloys coatings (e.g., nickel, uranium) as the targets for cyclotron and reactor generation of the radioisotopes. This review provides an evaluation of the role ILs …


Structural Annotation Of Electro- And Photochemically Generated Transformation Products Of Moxidectin Using High-Resolution Mass Spectrometry, Lisa Kotthoff, Sarah-Louise O'Callaghan, Jan Lisec, Tanja Schwerdtle, Matthias Koch Jan 2020

Structural Annotation Of Electro- And Photochemically Generated Transformation Products Of Moxidectin Using High-Resolution Mass Spectrometry, Lisa Kotthoff, Sarah-Louise O'Callaghan, Jan Lisec, Tanja Schwerdtle, Matthias Koch

Articles

Moxidectin (MOX) is a widely used anthelmintic drug for the treatment of internal and external parasites in food-producing and companion animals. Transformation products (TPs) of MOX, formed through metabolic degradation or acid hydrolysis, may pose a potential environmental risk, but only few were identified so far. In this study, we therefore systematically characterized electro- and photochemically generated MOX TPs using high-resolution mass spectrometry (HRMS). Oxidative electrochemical (EC) TPs were generated in an electrochemical reactor and photochemical (PC) TPs by irradiation with UV-C light. Subsequent HRMS measurements were performed to identify accurate masses and deduce occurring modification reactions of derived TPs …


Convective Instabilities Derived From Dissipation Of Chemical Energy, Reuben H. Simoyi, Matthew W. Eskew Aug 2019

Convective Instabilities Derived From Dissipation Of Chemical Energy, Reuben H. Simoyi, Matthew W. Eskew

Chemistry Faculty Publications and Presentations

Oxidation reactions of a series of organosulfur compounds by chlorite are excitable, autocatalytic, and exothermic and generate a lateral instability upon being triggered by the autocatalyst. This article reports on the convective instabilities derived from the reaction of chlorite and thiourea in a Hele-Shaw cell. Reagent concentrations used for the development of convective instabilities delivered a temperature jump at the wave front of 2.1 K. The reaction zone was 2 mm and due to normal cooling after the wave front, this induced a spike rather than the standard well-studied front propagation. Localized spatiotemporal patterns develop around the wave front. This …


Phenolate Derivatives Of Octanuclear Iron-Oxo-Pyrazolato Complexes; Enantiomeric Resolution Of T-Symmetry Species, Konstantinos Lazarou May 2019

Phenolate Derivatives Of Octanuclear Iron-Oxo-Pyrazolato Complexes; Enantiomeric Resolution Of T-Symmetry Species, Konstantinos Lazarou

FIU Electronic Theses and Dissertations

Octanuclear ferric complexes involving achiral phenolates of the general formula [Fe8(μ-O)4(μ-pz)12(R-C6H4O)4], (R = 4-NO2, 4-CN, 4-F, 4-Cl, 4-I, 4-CH3O, and 3-NO3), where synthesized and characterized by single crystal X-ray crystallography, elemental analysis, 1H-NMR, UV-Vis, IR, 57Fe Mössbauer spectroscopy and electrochemical methods (cyclic and differential pulse voltammetry). Results indicate that the nature of the phenolate substituents allows the fine tuning of the spectroscopic data of the compounds.

Subsequently, this project focused on the resolution of the racemic …


Highly Selective Fluorimetric Turn-Off Detection Of Copper (Ii) By Two Different Mechanisms In Calix[4]Arene-Based Chemosensors And Chemodosimeters, Justine O'Sullivan, John Colleran, Brendan Twamley, Frances Heaney Jan 2019

Highly Selective Fluorimetric Turn-Off Detection Of Copper (Ii) By Two Different Mechanisms In Calix[4]Arene-Based Chemosensors And Chemodosimeters, Justine O'Sullivan, John Colleran, Brendan Twamley, Frances Heaney

Articles

Isoxazolo‐pyrene tethered calix[4]arenes selectively detect copper(II) ions without interference from related perchlorate ions. The fluorescence emission of the probes, synthesised by nitrile oxide alkyne cycloaddition, and characterised by spectroscopic and crystallographic data, is rapidly reduced by Cu(II) ions. Detection limits are in the micromolar or sub‐micromolar range (0.3–3.6 μM) based on a 1 : 1 sensor:analyte interaction. Voltammetric behaviour and 1H NMR data provide new insights into the sensing mechanism which is dependent on the calixarene substitution pattern. When the calixarene lower rim is fully substituted, Cu(II) detection occurs through a traditional chelation mechanism. In contrast, for calixarenes 1,3‐disubstituted on …


Near-Infrared Photoluminescence And Electrochemiluminescence From An Exceptionally Simple Boron Difluoride Formazanate Dye, Ryan R. Maar, Ruizhong Zhang, David G. Stephens, Zhifeng Ding, Joe Gilroy Nov 2018

Near-Infrared Photoluminescence And Electrochemiluminescence From An Exceptionally Simple Boron Difluoride Formazanate Dye, Ryan R. Maar, Ruizhong Zhang, David G. Stephens, Zhifeng Ding, Joe Gilroy

Chemistry Publications

Electrochemiluminescence involves the generation of light via electrochemical reactions and has recently shown utility for single-cell imaging. To further develop this novel imaging platform, it is necessary to produce readily available dyes that photoluminesce and electrochemiluminesce in the near-infrared region to limit absorption by biological tissue. To address this need, we prepared a boron difluoride formazanate dye that exhibits near-infrared photoluminescence and electrochemiluminescence in two straightforward synthetic steps. Examination of its solid-state structure suggests that the N-aryl substituents have significant quinoidal character, which narrows the S1-S0 energy gap and leads to near-infrared absorption and photoluminescence. Electrochemical …


Mapping Of The Chromium And Iron Pyrazolate Landscape, Jessica Maria Lopez Oct 2018

Mapping Of The Chromium And Iron Pyrazolate Landscape, Jessica Maria Lopez

FIU Electronic Theses and Dissertations

The main objective of this project is to synthesize the first family of polynuclear chromium pyrazolate complexes. Complexity in analysis of the experimental magnetic data of multinuclear complexes arises from their (2S +1)N microstates, where S is the spin of each metal center and N is the number of metal centers. For example, high-spin (HS)-FeIII3 has 216 microstates and HS-FeIII8 ≈ 1.7x106 microstates (S= 5/2). However, complexes with chromium(III) S = 3/2 will have a noticeable reduction of microstates. Mononuclear complexes with formula [mer-CrCl3(pzH*)3] (pz*H = pyrazole, 3-Me-pzH, …


Aptamer Sensors For Drugs Of Abuse And Medical Biomarkers: Design, Engineering And Application In Complex Samples, Daniel Roncancio Jun 2018

Aptamer Sensors For Drugs Of Abuse And Medical Biomarkers: Design, Engineering And Application In Complex Samples, Daniel Roncancio

FIU Electronic Theses and Dissertations

Aptamers are short oligonucleotide sequences (DNA or RNA) capable of high affinity and specific binding to a molecule or a family of molecules. Aptamers are lower in cost and exhibit higher reproducibility when compared to antibodies and thus are well-suited for recognition and detection of small molecular targets such as drugs of abuse and small medical biomarkers. While aptamers have been extensively utilized for development of small molecule sensors, several limitations prevent measurements of complex or real-world samples. This dissertation describes methods, technologies, and assays that were developed with the goal of producing and/or improving aptamer-based sensors for target detection …


New Polynuclear Copper-Pyrazolate Complexes: Towards The Synthesis Of Photo- And Redox-Active Metal Organic Frameworks, Kaige Shi Jun 2018

New Polynuclear Copper-Pyrazolate Complexes: Towards The Synthesis Of Photo- And Redox-Active Metal Organic Frameworks, Kaige Shi

FIU Electronic Theses and Dissertations

The main objectives of this project are the synthesis and redox- or photo-active modification and CO2 adsorption studies of metal-organic frameworks (MOFs) based on Cu3-pyrazolate secondary building units (SBUs). Trinuclear copper(II) complexes of the formula [Cu33-O)(µ-4-R-pz)3X3]z have been studied extensively due to their redox, magnetic and catalytic properties. In earlier work, we have shown that trinuclear copper(II) complexes of the formula [Cu33-O)(µ-4-R-pz)3X3]z pz = pyrazolato anion; R = H, CH(O), Cl, Br and NO2; X = Cl, …


Nanomaterial-Based Electrochemical And Colorimetric Sensors For On-Site Detection Of Small-Molecule Targets, Bhargav Guntupalli Apr 2017

Nanomaterial-Based Electrochemical And Colorimetric Sensors For On-Site Detection Of Small-Molecule Targets, Bhargav Guntupalli

FIU Electronic Theses and Dissertations

An ideal biosensor is a compact and in-expensive device that is able to readily and rapidly detects different types of analytes with high sensitivity and specificity. The affectability of a biosensing methodology is subject to the limit of nanomaterials to transduce the target binding process to an improved perceptible signal, while the selectivity is accomplished by considering the binding and specificity of certain moieties to their targets. Keeping these requirements in mind we have chosen nanomaterials such as carbon nanotubes (CNTs) and gold nanoparticles (AuNPs) that has catalytic properties combined with their size, shape and configuration dependent chemical and physical …


Electrochemistry-Coupled To Mass Spectrometry In Simulation Of Metabolic Oxidation Of Methimazole: Identification And Characterization Of Metabolites, Kudzanai Chipiso, Reuben H. Simoyi Jan 2016

Electrochemistry-Coupled To Mass Spectrometry In Simulation Of Metabolic Oxidation Of Methimazole: Identification And Characterization Of Metabolites, Kudzanai Chipiso, Reuben H. Simoyi

Chemistry Faculty Publications and Presentations

Methimazole (MMI), an antithyroid drug, is associated with idiosyncratic toxicity. Reactive metabolites resulting from bioactivation of the drug have been implicated in these adverse drug reactions. Mimicry of enzymatic oxidation of MMI was carried out by electrochemically oxidizing MMI using a coulometric flow-through cell equipped with a porous graphite working electrode. The cell was coupled on-line to electrospray ionization mass spectrometry (EC/ESI-MS). ESI spectra were acquired in both negative and positive modes. In acidic medium, ESI spectral analysis showed that the dimer was the main product, while in neutral and basic media, methimazole sulfenic acid, methimazole sulfinic acid and methimazole …


Electrochemical Characterization Of Self-Assembled Monolayers On Gold Substrates Derived From Thermal Decomposition Of Monolayer-Protected Cluster Films, Michael C. Leopold, Tran T. Doan, Melissa J. Mullaney, Andrew F. Loftus, Christopher M. Kidd Aug 2015

Electrochemical Characterization Of Self-Assembled Monolayers On Gold Substrates Derived From Thermal Decomposition Of Monolayer-Protected Cluster Films, Michael C. Leopold, Tran T. Doan, Melissa J. Mullaney, Andrew F. Loftus, Christopher M. Kidd

Chemistry Faculty Publications

Networked films of monolayer-protected clusters (MPCs), alkanethiolate-stabilized gold nanoparticles, can be thermally decomposed to form stable gold on glass substrates that are subsequently modified with self-assembled monolayers (SAMs) for use as modified electrodes. Electrochemical assessment of these SAM-modified gold substrates, including double-layer capacitance measurements, linear sweep desorption of the alkanethiolates, and diffusional redox probing, all show that SAMs formed on gold supports formed from thermolysis of MPC films possess substantially higher defect density compared to SAMs formed on traditional evaporated gold. The density of defects in the SAMs on thermolyzed gold is directly related to the strategies used to assemble …


Electrochemical Characterization Of Protein Adsorption Onto Yngrt-Au And Vlgxe-Au Surfaces, Hanna Trzeciakiewicz, Jose Esteves-Villanueva, Rania Soudy, Kamaljit Kaur, Sanela Martic-Milne Aug 2015

Electrochemical Characterization Of Protein Adsorption Onto Yngrt-Au And Vlgxe-Au Surfaces, Hanna Trzeciakiewicz, Jose Esteves-Villanueva, Rania Soudy, Kamaljit Kaur, Sanela Martic-Milne

Pharmacy Faculty Articles and Research

The adsorption of the proteins CD13, mucin and bovine serum albumin on VLGXE-Au and YNGRT-Au interfaces was monitored by electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3−/4−. The hydrophobicity of the Au surface was tailored using specific peptides, blocking agents and diluents. The combination of blocking agents (ethanolamine or n-butylamine) and diluents (hexanethiol or 2-mercaptoethanol) was used to prepare various peptide-modified Au surfaces. Protein adsorption onto the peptide-Au surfaces modified with the combination of n-butylamine and hexanethiol produced a dramatic decrease in the charge transfer resistance, Rct, for all three proteins. In contrast, polar peptide-surfaces induced a minimal change in …


Au Nanostructured Surfaces For Electrochemical And Localized Surface Plasmon Resonance-Based Monitoring Of Α-Synuclein-Small Molecule Interactions., Xin R Cheng, Gregory Q Wallace, François Lagugné-Labarthet, Kagan Kerman Feb 2015

Au Nanostructured Surfaces For Electrochemical And Localized Surface Plasmon Resonance-Based Monitoring Of Α-Synuclein-Small Molecule Interactions., Xin R Cheng, Gregory Q Wallace, François Lagugné-Labarthet, Kagan Kerman

Chemistry Publications

In this proof-of-concept study, the fabrication of novel Au nanostructured indium tin oxide (Au-ITO) surfaces is described for the development of a dual-detection platform with electrochemical and localized surface plasmon resonance (LSPR)-based biosensing capabilities. Nanosphere lithography (NSL) was applied to fabricate Au-ITO surfaces. Oligomers of α-synuclein (αS) were covalently immobilized to determine the electrochemical and LSPR characteristics of the protein. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed using the redox probe [Fe(CN)6](3-/4-) to detect the binding of Cu(II) ions and (-)-epigallocatechin-3-gallate (EGCG) to αS on the Au-ITO surface. Electrochemical and LSPR data were complemented by Thioflavin-T (ThT) …


Au Nanostructured Surfaces For Electrochemical And Localized Surface Plasmon Resonance-Based Monitoring Of Α-Synuclein-Small Molecule Interactions., Xin R Cheng, Gregory Q Wallace, François Lagugné-Labarthet, Kagan Kerman Feb 2015

Au Nanostructured Surfaces For Electrochemical And Localized Surface Plasmon Resonance-Based Monitoring Of Α-Synuclein-Small Molecule Interactions., Xin R Cheng, Gregory Q Wallace, François Lagugné-Labarthet, Kagan Kerman

Chemistry Publications

In this proof-of-concept study, the fabrication of novel Au nanostructured indium tin oxide (Au-ITO) surfaces is described for the development of a dual-detection platform with electrochemical and localized surface plasmon resonance (LSPR)-based biosensing capabilities. Nanosphere lithography (NSL) was applied to fabricate Au-ITO surfaces. Oligomers of α-synuclein (αS) were covalently immobilized to determine the electrochemical and LSPR characteristics of the protein. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed using the redox probe [Fe(CN)6](3-/4-) to detect the binding of Cu(II) ions and (-)-epigallocatechin-3-gallate (EGCG) to αS on the Au-ITO surface. Electrochemical and LSPR data were complemented by Thioflavin-T (ThT) …


Development Of A Lab-On-A-Chip Device For Rapid Nanotoxicity Assessment In Vitro, Pratikkumar Shah Dec 2014

Development Of A Lab-On-A-Chip Device For Rapid Nanotoxicity Assessment In Vitro, Pratikkumar Shah

FIU Electronic Theses and Dissertations

Increasing useof nanomaterials in consumer products and biomedical applications creates the possibilities of intentional/unintentional exposure to humans and the environment. Beyond the physiological limit, the nanomaterialexposure to humans can induce toxicity. It is difficult to define toxicity of nanoparticles on humans as it varies by nanomaterialcomposition, size, surface properties and the target organ/cell line. Traditional tests for nanomaterialtoxicity assessment are mostly based on bulk-colorimetric assays. In many studies, nanomaterials have found to interfere with assay-dye to produce false results and usually require several hours or days to collect results. Therefore, there is a clear need for alternative tools that can …


Synthesis Of Homo- And Heterobimetallic NiIi–MIi (M = Fe, Co, Ni, Zn) Complexes Based On An Unsymmetric Ligand Framework: Structures, Spectroscopic Features, And Redox Properties, Denan Wang, Sergey V. Lindeman, Adam T. Fiedler Sep 2014

Synthesis Of Homo- And Heterobimetallic NiIi–MIi (M = Fe, Co, Ni, Zn) Complexes Based On An Unsymmetric Ligand Framework: Structures, Spectroscopic Features, And Redox Properties, Denan Wang, Sergey V. Lindeman, Adam T. Fiedler

Chemistry Faculty Research and Publications

Several homo- and heterobimetallic NiII–MII complexes (MII = Fe, Co, Ni, Zn) supported by an unsymmetric polydentate ligand (L13−) are reported (L13− is the trianion of 2-[bis(2-hydroxy-3,5-tert-butylphenyl)aminomethyl]-4-methyl-6-[(2-pyridylmethyl)iminomethyl]phenol). The L13− chelate provides two distinct coordination environments: a planar tridentate {N2O} site (A) and a tetradentate {NO3} site (B). Reaction of L13− with equimolar amounts of NiII and MII salts provides bimetallic complexes in which the NiII ion exclusively occupies the tetragonal A-site and the MII ion is found …


Intramolecular Hydrogen Bonding In CuIi Complexes With 2,6-Pyridinedicarboxamide Ligands: Synthesis, Structural Characterization, And Physical Properties, Denan Wang, Sergey V. Lindeman, Adam T. Fiedler Sep 2013

Intramolecular Hydrogen Bonding In CuIi Complexes With 2,6-Pyridinedicarboxamide Ligands: Synthesis, Structural Characterization, And Physical Properties, Denan Wang, Sergey V. Lindeman, Adam T. Fiedler

Chemistry Faculty Research and Publications

The significance of second-sphere interactions in synthetic catalysts and metalloenzyme active sites has encouraged the development of ligand frameworks capable of supporting intramolecular hydrogen-bonding networks. With this approach in mind, we prepared a series of 2,6-pyridinedicarboxamide ligands (H2LX) that feature outer-sphere heterocyclic groups (pyridine, pyrimidine, or quinoline rings). Reaction with CuCl2 yields complexes with the general formula [CuCl2(LX{H}2)] (1X), in which the pincer ligands coordinate to the CuII center in a tridentate fashion through the central pyridine and two amidato nitrogen atoms. The LX …


Dications Of Benzylidenefluorene And Diphenylmethylidene Fluorene: The Relationship Between Magnetic And Energetic Measures Of Antiaromaticity, Catherine Do, Julianne Hatfield, Shirali Patel, D Vasudevan, Cornelia Tirla, Nancy S. Mills Jan 2011

Dications Of Benzylidenefluorene And Diphenylmethylidene Fluorene: The Relationship Between Magnetic And Energetic Measures Of Antiaromaticity, Catherine Do, Julianne Hatfield, Shirali Patel, D Vasudevan, Cornelia Tirla, Nancy S. Mills

Chemistry Faculty Research

Oxidation of m- and p-substituted benzylidene fluorenes to antiaromatic dications was attempted by electrochemical and chemical means. Electrochemical oxidation to dications was successful for benzylidene fluorenes with p-methoxy, p-methyl, p-fluoro, and unsubstituted phenyl rings in the 3-position; attempts to oxidize the m-substituted derivatives via electrochemistry were unsuccessful. Chemical oxidation with SbF5/SO2ClF gave the dication of 9-[(4-methoxyphenyl)methylene]-9H-fluorene cleanly; oxidation of all other substituted benzylidene fluorenes resulted in mixtures of products. The excellent linear relationship between the chemical shifts calculated by the GIAO method and the experimental shifts for the p-methoxy-substituted benzylidene fluorene dication …


Diffuse-Charge Dynamics Of Ionic Liquids In Electrochemical Systems, Hui Zhao Jan 2011

Diffuse-Charge Dynamics Of Ionic Liquids In Electrochemical Systems, Hui Zhao

Mechanical Engineering Faculty Research

We employ a continuum theory of solvent-free ionic liquids accounting for both short-range electrostatic correlations and steric effects (finite ion size) [Bazant et al., Phys. Rev. Lett. 106, 046102 (2011)] to study the response of a model microelectrochemical cell to a step voltage. The model problem consists of a 1-1 symmetric ionic liquid between two parallel blocking electrodes, neglecting any transverse transport phenomena. Matched asymptotic expansions in the limit of thin double layers are applied to analyze the resulting one-dimensional equations and study the overall charge-time relation in the weakly nonlinear regime. One important conclusion is that our …


Enhanced Electrochemistry Of Nanoparticle-Embedded Polyelectrolyte Films: Interfacial Electronic Coupling And Distance Dependence, Callie E. Dowdy, Michael C. Leopold Nov 2010

Enhanced Electrochemistry Of Nanoparticle-Embedded Polyelectrolyte Films: Interfacial Electronic Coupling And Distance Dependence, Callie E. Dowdy, Michael C. Leopold

Chemistry Faculty Publications

Factors affecting the electronic communication believed to be responsible for the enhanced solution electrochemistry observed at electrodes modified with hybrid polyelectrolyte–nanoparticle (PE–NP) film assemblies were systematically investigated. Specifically, the faradaic current and voltammetric peak splitting recorded for cyclic voltammetry of ferricyanide redox species (Fe(CN)63−/4−) at films constructed with various architectures of citrate-stabilized gold NPs embedded in polyelectrolyte films composed of poly-l-lysine and poly-S-styrene were used to establish the relative importance of both distance and electronic coupling. Layer-by-layer construction of PE–NP films allowed for the position and density of NPs to be varied within the film to assess electronic coupling between …


Adsorption Efficiency And Partitioning Capabilty Of Surfactant Monolayers On Gold, Carrie Jo M. Pruitt Jan 2010

Adsorption Efficiency And Partitioning Capabilty Of Surfactant Monolayers On Gold, Carrie Jo M. Pruitt

Mahurin Honors College Capstone Experience/Thesis Projects

We are investigating adsorption efficiencies of sodium dodecyl sulfate (SDS) from pH 7 phosphate buffer onto polycrystalline gold substrates using electrostatics as the primary driving force via electrochemical control of the gold surface potential. It is shown through surface capacitance measurements by electrochemical impedance spectroscopy that the adsorption occurs readily. Measurement of the adsorption isotherms of SDS onto the substrate via the change in surface capacitance as a function of the bulk concentration of SDS has allowed us to determine that the minimum concentration of SDS required for efficient adsorption is below 0.011 mM. The investigation of the influence of …


Tricarbonylrhenium(I) And Manganese(I) Complexes Of 2-(Pyrazolyl)-4-Toluidine, Brendan J Liddle, Sarath Wanniarachchi, Sergey V. Lindeman, James R. Gardinier Jan 2010

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(pzAnMe), has been prepared and characterized including by single crystal X-ray diffraction studies. The reactions between H(pzAnMe) and M(CO)5Br afford fac-MBr(CO)3[H(pzAnMe)] (M = Mn, 1a; Re, 1b) complexes. The ionic species {fac-M(CH3CN)(CO)3[H(pzAnMe)]}(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(pzAnMe)]+ …


Β-Diketonate, Β-Ketoiminate, And Β-Diiminate Complexes Of Difluoroboron, Felipe P. Macedo, Chengeto Gwengo, Sergey Lindeman, Mark D. Smith, James R. Gardinier Jul 2008

Β-Diketonate, Β-Ketoiminate, And Β-Diiminate Complexes Of Difluoroboron, Felipe P. Macedo, Chengeto Gwengo, Sergey Lindeman, Mark D. Smith, James R. Gardinier

Chemistry Faculty Research and Publications

A series of β-diketonate, keto(aryl)iminato, and β-bis(aryl)iminato complexes of difluoroboron, twenty in total, have been prepared to assess the impact of chelate ring and aniline substitution on the structural, electrochemical, and photophysical properties of these ubiquitous chelates. DFT (B3LYP/6-31G*) calculations supplemented the experimental results and both demonstrated that replacing oxygen with the more electron-donating aniline groups serves to only fine-tune the electronic properties because both the HOMO and LUMO energies are affected by such substitution. The electronic properties of all compounds are most greatly influenced by the nature of the substituents bound to the carbon portion of the chelate ring. …


Monolayer-Protected Nanoparticle Film Assemblies As Platforms For Controlling Interfacial And Adsorption Properties In Protein Monolayer Electrochemistry, Andrew F. Loftus, Katelyn P. Reighard, Susanna A. Kapourales, Michael C. Leopold Jan 2008

Monolayer-Protected Nanoparticle Film Assemblies As Platforms For Controlling Interfacial And Adsorption Properties In Protein Monolayer Electrochemistry, Andrew F. Loftus, Katelyn P. Reighard, Susanna A. Kapourales, Michael C. Leopold

Chemistry Faculty Publications

Assembled films of nonaqueous nanoparticles, known as monolayer-protected clusters (MPCs), are investigated as adsorption platforms in protein monolayer electrochemistry (PME), a strategy for studying the electron transfer (ET) of redox proteins. Modified electrodes featuring MPC films assembled with various linking methods, including both electrostatic and covalent mechanisms, are employed to immobilize cytochrome c (cyt c) for electrochemical analysis. The background signal (non-Faradaic current) of these systems is directly related to the structure and composition of the MPC films, including nanoparticle core size, protecting ligand properties, as well as the linking mechanism utilized during assembly. Dithiol-linked films of Au225(C6)75 are …


Electrochemical Separation Of Curium And Americium, David W. Hatchett, Kenneth Czerwinski Jan 2008

Electrochemical Separation Of Curium And Americium, David W. Hatchett, Kenneth Czerwinski

Separations Campaign (TRP)

The objective was to use electrochemical techniques to develop a thermodynamic understanding of actinide and lanthanide species in RTIL solutions, and use this data to effectively separate species with very similar chemical properties.

In consultation with a DOE collaborator, electrochemical methods and materials were evaluated and used to exploit the thermodynamic differences between similar chemical species enhancing the ability to selectively target and sequester individual species from mixtures. This project, in its third year, successfully completed phases 1, 2. Phase 3 was partially completed. The project expanded to include phase 4.

The following were specific goals for 2007-2008:

• To …


F-Element Electrochemistry In Rtil Solutions: Electrochemical Separation Of Lanthanides And Actinides, David W. Hatchett Jan 2008

F-Element Electrochemistry In Rtil Solutions: Electrochemical Separation Of Lanthanides And Actinides, David W. Hatchett

Separations Campaign (TRP)

Electrochemical methods can be used to effectively separate actinide and lanthanide species from complex mixtures. This is based on the unique electrochemical properties of each specific target species. In studies it has been found that, with the exception of Ce, aqueous solutions provide unsuitable electrochemical windows to effectively evaluate the thermodynamic properties that are useful for chemical separations. Therefore, a more novel approach was examined which eliminated the aqueous solution with a room temperature ionic liquid (RTIL) solution. RTIL solutions do not suffer from the side reactions that are prominent in aqueous environments. In addition, the potential window is much …