Chemistry Commons^™

A Practical Photoelectrochemical Cell Using Nonprecious Metal Electrodes, Patrick Enright, Tony Betts, John Cassidy

Articles

Abstract: Photoelectrochemical cells (PECs) can be used to harvest light from the oxidation of dissolved organic matter. Similar to fuel cells but requiring light to operate, PECs contain a light assisted electrode that oxidises electron rich materials (anode); these electrons then flow to a typically Pt cathode where O₂ is normally the electron acceptor. In this work a PEC cell containing inexpensive materials was shown to (a) mineralise typical organic compounds present in waste water and (b) produce electricity from their decomposition. The PEC cell consisted of a TiO₂ coated conducting ink anode exposed to a light source, …

Comment On C.E. Close, M.R. Gleeson And J.T. Sheridan "Monomer Diffusion Rates In Photopolymer Material Part 1. Low Spatial Frequency Holographic Gratings, Vincent Toal, Suzanne Martin, Izabela Naydenova

Articles

COMMENT: on C. E. Close, M. R. Gleeson and J. T. Sheridan “Monomer diffusion rates in photopolymer material.Part I. Low spatial frequency holographic gratings” J. Opt. Soc. Am. B / Vol. 28, No. 4 / April 2011 pp 658- 666 [1]

Structural And Photochemical Behavior Of Phenyl And Dihydrophenyl Sulfonamidecinnamic Acids, Sergey Zinovchik

Masters Theses

Controlling chemical processes and directing product formation has been a long sought-after goal of synthetic chemists. Most synthesis techniques focus on reactions performed in solution. Such traditional approaches have several disadvantages including unwanted side products, disrupting chemical processes and low reaction yields. A proposed approach to circumvent these drawbacks focuses on performing reactions in the solid state. This method promises better control and higher reaction yields due to the controlled environment of the reaction components. Because molecules in the solid state are effectively fixed, reactions can be performed with a high degree of selectivity, reducing side products and eliminating unwanted …

Synthesis, Assembly, And Characterization Of Monolayer-Protected Gold Nanoparticle Films For Protein Monolayer Electrochemistry,, Tran T. Doan, Michael H. Freeman, Adrienne R. Schmidt, Natalie T. Nguyen, Michael C. Leopold

Chemistry Faculty Publications

Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently incorporated into film assemblies that serve as adsorption platforms for protein monolayer electrochemistry (PME). PME is utilized as the model system for studying electrochemical properties of redox proteins by confining them to an adsorption platform at a modified electrode, which also serves as a redox partner for electron transfer (ET) reactions. Studies have shown that gold nanoparticle film assemblies of this nature provide for a more homogeneous protein adsorption environment and promote ET without distance dependence compared to the more traditional systems modified …

Charge Saturation And Neutral Substitutions In Halomethanes And Their Group 14 Analogues, Bernard K. Wittmaack, Chad Crigger, Matthew Guarino, Kelling J. Donald

Chemistry Faculty Publications

A computational analysis of the charge distribution in halomethanes and their heavy analogues (MH_4-nX_n: M= C, Si, Ge, Sn, Pb; X = F, Cl, Br, I) as a function of _n uncovers a previously unidentified saturation limit for fluorides when M ≠ C. We examine the electron densities obtained at the CCSD, MP2(full), B3PW91, and HF levels of theory for 80 molecules for four different basis sets. A previously observed substituent independent charge at F in fluoromethanes is shown to be a move toward saturation that is restricted by the low polarizability of C. This limitation …

Method Developments To Analyze Caffeine And Acesulfame-K Concentrations In Natural Waters In And Around Charleston, Il, Usa, Laleen Bodhipaksha

Masters Theses

Analytical methods using batch solid phase extraction were developed for two chemical markers, caffeine and acesulfame-K, to assess anthropogenic water contamination of natural water bodies in and around Charleston, Illinois.

Measurements were conducted on 12 different extracted samples using reverse phase HPLC. Two creek samples showed the presence of acesulfame-K (0.45 ± 0.10 and 0.25 ± 0.06 ppb) and two creek samples showed the presence of caffeine (3 .1 ± 1.2 and 1.6 ± 0.6 ppb ). Effluent from the Charleston waste water treatment plant showed an acesulfame-K concentration of 0.67 ± 0.15 ppb.

These results indicate measurement of both …

Synthesis Of Molecular Containers Based On Modifications Of Resorcin(4)Arene And Calix(4)Arene, Anupama Makineni

Masters Theses

This research work was mainly focused on the synthesis of molecular containers based on modifications ofresorcin[4]arene and calix[4]arene.

The modifications of resorcin[ 4 ]arene include the attempts to attach a phthalimide featured linker onto the phenol hydroxyl groups of resorcin[4]arene. A few halogen leaving groups were used, including fluorine, chlorine, and bromine. The substitution with tetraflorophthalimide resulted in a mixture of regio-isomeric products, whereas for 4,5-dichloro- and 4,5-dibromophthalimides, no desired substitution product was formed. It was, however, discovered that both 4,5-dichloro- and 4,5-dibromophthalimides forms monoclinic crystals. The second modification of resorcin[4]arene focused on functionalizations of both upper and lower rims …

Two-Photon Cross Section Enhancement Of Photochromic Compounds For Use In 3d Optical Data Storage, Gheorghe Luchita

Electronic Theses and Dissertations

Rewritable photochrome-based 3D optical data storage requires photochromic molecules with high two-photon absorption (2PA) cross sections. Currently, the low value of two-photon absorption cross sections of existing photochromes makes them unsuitable for practical application in 3D data storage. Worldwide attempts to increase the cross section of photochromic molecules by altering the chemical structure have yielded poor results. In this work, two ways to increase the two-photon absorption cross sections of photochromes were investigated. In the first method, partial success demonstrated by extending the conjugation of a photochromic molecule, a high two-photon absorption cross section of the closed form isomer and …

Self-Assembly And Photophysics Of Selected Organic Materials And Two-Photon Bioimaging With Profluorescent Nitroxides, Polyelectrolyte Nanoparticles, And Squaraine Probes, Hyo Yang Ahn

Electronic Theses and Dissertations

Two-photon absorption and upconverted fluorescence has been utilized in a variety of applications in pure science and engineering. Multiphoton-based techniques were used in this research in order to understand photophysical and chemical characteristics of several fluorescent dyes and to demonstrate some of their key applications. Two-photon fluorescence microscopy (2PFM) has become a powerful technique in bio-photonics for non-invasive imaging in the near-infrared (NIR) region (700~1000 nm) that often results in less photobleaching. In Chapter 1, there is a brief introduction to fluorescence, examples of fluorescence materials, and a discussion of the advantages of two-photon absorption. 2PFM imaging was utilized in …

Investigation Of Nanoceria-Modified Platinum-Gold Composite Electrodes For The Electrochemical Reduction Of Oxygen In Alkaline Media, Rahul Hegishte

Electronic Theses and Dissertations

Platinum-gold and nanoceria-modified platinum-gold electrodes were prepared on a platinum surface via electrochemical reduction of solutions of platinum and gold salts in the dispersion of nanoceria. The molar ratios of Pt and Au were varied in both PtAu and PtAu/CeO₂ electrodes while the total concentration of the metals was maintained at 2 x 10⁻³M and the concentration of nanoceria was maintained constant at 5 x 10⁻³M. The electrodes were characterized by their cyclic voltammetry curves in 0.5M sulfuric acid solution. The electrochemically active area of the electrodes was determined using the copper underpotential deposition method. The linear sweep voltammograms of …

The Application Of Two-Photon Absorbing Probes In Lysosomal, Zinc Ion Sensing And Folate Receptor-Targeted Bioimaging, Xuhua Wang

Electronic Theses and Dissertations

Two-photon fluorescence microscopy (2PFM) has become a powerful technique for bioimaging in non-invasive cancer diagnosis and also investigating the mechanization and original of a variety of diseases by tracking various biological processes. Because the fluorescence emission by two photon absorbing (2PA) is directly proportional to the square of the intensity of excitation light, this intrinsic property of 2PA provides 2PFM great advantages over traditional one-photon fluorescence microscopy (1PFM), including high 3D spatial localization, less photodamage and interference from biological tissue because of using longer wavelength excitation (700-1300 nm). However, most 2PA probes are hydrophobic and their photostabilities are questionable, severely …

The Unsuspected Pathway Of The Allosteric Transition In Hemoglobin, Stefan Fischer, Kenneth W. Olsen, Kwangho Nam, Martin Karplus

Chemistry: Faculty Publications and Other Works

Large conformational transitions play an essential role in the function of many proteins, but experiments do not provide the atomic details of the path followed in going from one end structure to the other. For the hemoglobin tetramer, the transition path between the unliganded (T) and tetraoxygenated (R) structures is not known, which limits our understanding of the cooperative mechanism in this classic allosteric system, where both tertiary and quaternary changes are involved. The conjugate peak refinement algorithm is used to compute an unbiased minimum energy path at atomic detail between the two end states. Although the results confirm some …

Detecting Specific Saccharides Via A Single Indicator, Soojin Lim, Jorge O. Escobedo, Mark Lowry, Robert M. Strongin

Chemistry Faculty Publications and Presentations

An improved synthesis of a rhodamine boronic acid indicator is reported. This compound is used in an optimized data collection protocol for wavelength- and time-dependent selectivity of sugars such as fructose and ribose derivatives. One indicator is thus used to selectively distinguish structurally related sugar analytes.

The Relative Recoverability Of Dna And Rna Profiles From Forensically Relevant Body Fluid Stains, Charly Parker

Electronic Theses and Dissertations

Biological material (fluids or tissues) whether from the victim or suspect is often collected as forensic evidence, and methods to obtain and analyze the DNA found in that material have been well established. The type of body fluid (i.e. blood, saliva, semen, vaginal secretions, and menstrual blood) from which the DNA originated is also of interest, and messenger RNA typing provides a specific and sensitive means of body fluid identification. In order for mRNA profiling to be utilized in routine forensic casework, RNA of sufficient quantity and quality must be obtained from biological fluid stains and the methods used for …

The Study Of Three Different Layered Structures As Model Systems For Hydrogen Storage Materials, Muzaffer Tonguç Öztek

Electronic Theses and Dissertations

The strength and success of the hydrogen economy relies heavily on the storage of hydrogen. Storage systems in which hydrogen is sequestered in a solid material have been shown to be advantageous over storage of hydrogen as a liquid or compressed gas. Many different types of materials have been investigated, yet the desired capacity and uptake/release characteristics required for implementation have not been reached. In this work, porphyrin aggregates were investigated as a new type of material for hydrogen storage. The building blocks of the aggregates are porphyrin molecules that are planar and can assume a face to face arrangement …

Characterizing Potential Sustainable Energy Feedstocks, Jesse George Thompson

Dissertations

Trap grease offers a promising and less expensive alternative to food grade vegetable oils for biodiesel production, but its commercial marketability could be affected by its intense and offensive odor. Identification, quantitation and eventual elimination of the odorant compounds are vital challenges that need to be addressed before commercialization can be achieved. A rapid method using HS-SPME and GC/MS was developed in this study to identify and quantify the major volatile odorant compounds present in trap grease. The main odorant compounds were identified as short chain free fatty acids (SC-FFA) from C₄ - C₁₀.

Sensory evaluations by …

Glucosamine-Induced Insulin Resistance In Primary Rat Hepatocytes And The Role Of Selenium As An Insulin Mimetic, Sandhya N. Adiyodi Veetil

Dissertations

Type 2 diabetes is mediated by insulin resistance, the inability of insulin to elicit a normal biological response in insulin responsive tissues. Several cellular models have been utilized to determine the mechanism of induction of insulin resistance but questions remain unanswered. One model, implicates the products of the Hexosamine Biosynthetic Pathway (HBP) in the induction of insulin resistance under hyperglycemia. The major end product of HBP, UDP-GlcNAc, is the substrate for O-GlcNAc transferase, an enzyme that catalyzes the O-GlcNAcylation of numerous proteins. This modification may play a role in induction of insulin resistance and thus needs to be evaluated in …

Spectroscopic Study Of New Sensors For Organophosphates, Metals, And Cyanide Based On Rhodamine And Cholic Acid Derivatives, Arambe Gedara Aruna Weerasinghe

Dissertations

Despite the increasing interest in developing sensors for nerve gas agents, efficient detection remains challenging. Among the various sensors developed so far, fluorescence sensors play an important role due to their simplicity. We developed six new rhodamine-based compounds that can be used as fluorescent turn-on sensors. Compound 1 and 3 gave high fluorescent enhancement with diethyl chlorophosphate (DCP) compared to the other compounds. Very high selectivity and sensitivity were observed as these compounds did not show significant fluorescent enhancement with dimethyl methylphosphonate (DMMP), HC1 and transition metal ions. The potential sensor can be used in solution as well as on …

Structural Characterization Of Water-Soluble Atmospheric Organic Matter By Ultrahigh-Resolution Mass Spectrometry, Jeffrey P. Leclair

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

Isolated water-soluble analytes extracted from fog water collected during a radiation fog event near Fresno, CA were analyzed using collision induced dissociation and ultrahigh-resolution mass spectrometry. Tandem mass analysis was performed on scan ranges between 100-400 u to characterize the structures of nitrogen and/or sulfur containing species. CHNO, CHOS, and CHNOS compounds were targeted specifically because of the high number of oxygen atoms contained in their molecular formulas. The presence of 22 neutral losses corresponding to fragment ions was evaluated for each of the 1308 precursors. Priority neutral losses represent specific polar functional groups (H2O, CO2, CH3OH, HNO3, SO3, etc., …

Synthesis Of Chiral Ferrosalen Ligands And Their Applications In Asymmetric Catalysis, Xiang Zhang

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

A new series of chiral ferrosalen ligands was designed and synthesized. The special feature of the ferrosalen ligands is that the chirality originated from the planar chiral ferrocenyl structure. For most known salen ligands, chirality comes from central and axial chiral centers. The key building block for the construction of these ferrosalen ligands was synthesized stereoselectively by a chiral auxiliary approach. This approach does not consume any chiral material, and does not require chiral HPLC resolution. Using this method, nine ligands were prepared using ferrocene as the starting material. In addition, the steric hindrance was modulated by changing the cyclopentadienyl …

Cell And Protein-Based Sensing Systems For The Detection Of Environmentally And Physiologically Relevant Molecules, Kendrick Bruce Turner

Theses and Dissertations--Chemistry

The detection of small molecules in complex sample matrices such as environmental (surface and ground water, sediment, etc.) and biological (blood, serum, plasma, etc.) samples is of paramount importance for monitoring the distribution of environmental pollutants and their patterns of exposure within the population as well as diagnosing and managing diseases. Biosensors have demonstrated a singular ability to sensitively and selectively detect analytes in complex samples without the need for extensive sample preparation and pretreatment. Nature has demonstrated myriad examples of exquisite selectivity in spite of complexity and we seek to take advantage of that attribute in the development of …

Opioid Codrugs For Pain Management, Ujjwal Chakraborty

Theses and Dissertations--Chemistry

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissus damage or described in terms of such damage. Opioids are effective in treating moderate to severe pain, but opioid alone therapy is associated with several adverse effects, development of tolerance and addiction potential. One way to solve these problems is to administer opioids with adjuvant drugs. In this project several opioid molecules were combined with other adjuvant drugs in a single chemical entity to form a codrug.

A series of codrugs were prepared by conjugation of an opioid with S-(-)-nornicotine, ketamine, norketamine and gabapentin. Several …

Fabrication And Preliminary Characterization Of Hydrophobic Silica Aerogel Films For Oil Remediation Studies, Ellen Yang

Pomona Senior Theses

Due to the potential of oil sorbents for oil spill clean-up, hydrophobic silica-based aerogel thin films have been synthesized and characterized by various methods. Aerogels were prepared using a two-step acid/base sol-gel process and functionalized with trimethylchlorosilane in hexane, followed by drying in ambient conditions. After film deposition by spin-coating, samples were characterized by scanning electron microscopy, nitrogen adsorption analysis (BET surface area = 377.66 m2 /g), and variable-angle spectroscopic ellipsometry (thickness of 287.00 ± 0.85 nm, refractive index of 1.08, porosity of 80.9%). Unlike previous studies with aerogel films, quartz crystal microbalance with dissipation monitoring (QCM-D) was applied to …

Interfacial Effects On Dielectric Properties Of Polymer-Particle Nanocomposites, Sasidhar Siddabattuni

Doctoral Dissertations

"Dielectric materials that are capable of efficiently storing large amounts of electrical energy are desirable for many electronic and power devices. Since the electrical energy density in a dielectric material is limited to εV_b²/2, where ε is the dielectric permittivity of the material and V_b is the breakdown strength, increased permittivity and breakdown strength are required for large energy storage density. Interfacial effects can influence the dielectric properties, especially dielectric breakdown resistance in polymer-particle nanocomposites. Several functional organophosphates were used to modify the surface of titania and barium titanate nanofiller particles in order to achieve covalent interface …

Development Of A Versatile Man-Portable Obscurant Aerosol Generator: Characterization Of Aerosols In Laboratory And Field Environments, Robert William Schaub

Doctoral Dissertations

"The objective of research presented in this dissertation was to develop a readily deployable and environmentally benign obscurant system operating with a single liquid for the visible and near infrared regions. To achieve this objective, research efforts were directed in two areas: i. Evaluating suitable biogenic oils to replace the United States Army's "Fog Oil" as the obscurant fluid. ii. Design, fabrication and validation of a prototype man-portable / vehicle mountable modular obscurant aerosol generator. Petroleum middle distillate - "Fog Oil" has been the material of choice for wide area obscuration for several decades. Large quantities (thousands gallons) of the …

Part-I Characterization Of Phorbol Ester; The Predominant Toxic Component Of Jathropha Curcas And Development Of An Efficient Process For The Detoxification Of Jathropha Curcas Meal Part-Ii Quantification Of 2-Hydroxy-4-(Methylthio) Butanoic Acid And Pantothenic Acid In Bovine Serum And Sea Water Matrices, Balaji Viswanathan

Doctoral Dissertations

"Jatropha curcas is has often been touted as the most sustainable biofuel source. Jatropha curcas is a drought resistant perennial plant belonging to the Euphorbiaceae family. Interest in this plant as a biofuel source is related to high lipid (triglyceride) content of its seeds. However, economics of jatropha as a biofuel source has been marred by the toxicity of the oil and its protein rich meal. As a result of high toxicity the protein rich meal is used only as a very low or no economic value organic fertilizer. Economic return from jatropha can be dramatically enhanced through development of …

Synthesis And Binding Studies Of Peptide Mimetics, Anion Receptors, And Kinase Inhibitors, Nanditha G. Nair

Doctoral Dissertations

"A series of novel purine-based fluoroaryl triazoles were synthesized and assayed for their neuroprotective effects of hippocampal slice culture exposed to amyloid beta (Aß) oligomers. A monofluorinated triazole has been identified which has comparable neuroprotective effect as that of flavopiridol and roscovitine against the Aß induced neurotoxicity. Carnosine and histidine are biologically interesting antioxidants. In order to probe whether they exert their antioxidant effect through metal ion chelation, the Cu(ll) ion chelating abilities of these compounds were measured by UV-vis spectroscopy. Amyloid beta, the major component of senile plaques in Alzheimer's disease, is known to complex transition metal ions through …

Aerogels And Films Through Free Radical Polymerization, Anand G. Sadekar

Doctoral Dissertations

"Aerogels are porous lightweight materials, unique among all solids in terms of low density, low thermal conductivity, low dielectric constants and high acoustic attenuation. The penalty for those exceptional properties is fragility. That issue has been addressed by bridging covalently (crosslinking) the elementary nanoscopic building blocks of silica aerogels with polymers. To streamline the crosslinking process we synthesized a bidentate free radical initiator (Si-AIBN) that gets attached on the skeletal nanoparticles and induces crosslinking by surface initiated polymerization (SIP). Here, we extend the scope of Si-AIBN in two directions: (a) we demonstrate extremely adhering, covalently attached polymer coatings on oxidized …

One Pot Synthesis Of Metal, Carbides And Polymeric Aerogels, Naveen K. Chandrasekaran

Doctoral Dissertations

"Ultra-low density, three-dimensional assemblies of nanoparticles are referred to as aerogels, and typically are derived from supercritical fluid (SCF) drying of wet-gels. Aerogels are generally fragile materials, but that issue has been addressed successfully by X-aerogels, in which the inorganic nanoparticle framework plays the role of the template for the accumulation of polymer that connects covalently and crosslinks the nanoparticles. The resulting materials can be 300x stronger than the native network, for a nominal increase in density by a factor of 3x. Since the exceptional mechanical properties of X-aerogels are traced to the conformal polymer coating, it was reasonable to …

Preliminary Model Development Of Metal Complexation Of Polyester Derivatives Of 2,2'-Biimidazole, Shelonda Rena Taylor Finch

Doctoral Dissertations

"The objective of this study was to develop a chemical model for metal ion complex formation by a macroligand system with multi-metal binding sites using 2,2'-biimidazole as the starting molecule of the ligand system. Prior studies in this laboratory guided the selection of diesters and hydroxyethyl derivatives of 2,2'-biimidazole as model monomers. In addition, metal ion complexation studies with 2,2'-biimidazole derivatives were conducted. As a result, crystal structures of 1,1'-di(methylpropionato)-2,2-biimidazole, 2,2'-bis(1H-imidazolium) dinitrate and silver 2,2'-bis(1H-imidazolium) trinitrate, were reported. The crystal structures indicated a dependence upon the binding ability of the protonated 2,2'-biimidazole and counter ions. transesterification of the diesters and …