Chemistry Commons^™

A Highly Soluble Asymmetric Perylene-Bis (Dicarboximide)-Acceptor System Incorporating A Methylene Bridged Methoxybenzene-Donor: Solvent Dependence Of Charge Transfer Interactions, Rene M. Williams

Turkish Journal of Chemistry

The synthesis and photophysical properties of an asymmetrically substituted perylene-bis(dicarboximide), (PDI), system (1) containing a methylene bridged 4-methoxy-benzene donor and a solubilizing branched C_{13} alkyl chain are described. As compared to most PDIs, the fluorescence of 1 is strongly quenched in polar (but not in non-polar) solvents due to a photo-induced electron transfer process. Transient absorption spectroscopy and time resolved emission in e.g. acetonitrile indicates that upon excitation the radical anion of the PDI is formed with a rate of ca. 3.5 \times 10^9s^{-1}, and the charge transfer state has a lifetime of ca. 3 ns. A Frontier Molecular Orbital …

A Study Of Growth And Breakdown Of Passive Film On Copper Surface By Electrochemical Impedance Spectroscopy, Amtul Naseer, Athar Yaseen Khan

Turkish Journal of Chemistry

Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry were used to investigate the oxide layer formed on a copper disc electrode and the changes that took place when treated potentiostatically in the range of -0.3 V to 0.9 V in aqueous buffer solution of pH 9.2. Equivalent circuits were used to model the response of the electrode, initially at equilibrium to an applied potential. These circuits were proposed for different potential ranges in order to illustrate the Cu/oxide/electrolyte system and its properties in terms of 2 interfaces. A criterion for the applicability of equivalent circuit models was discussed. Changes in the …

Pore Structure And Surface Acidity Evaluation Of Fe-Pilcs, Suna Balci, Eli̇f Gökçay

Turkish Journal of Chemistry

Fe-PILCs via different conditions using smectites from Hancili (Turkey) and Wyoming (USA) were synthesised. Presaturation had little effects on the basal spacing values while it had important effects on thermal stabilities of the products. Products having basal spacing (d_{001}) around 1.30 nm and surface area up to 160 m^2 g^{-1} were obtained. The thermal behaviour, X-ray diffraction (XRD) patterns, and nitrogen adsorption/desorption experiments confirmed that thermally stable and micro-mesoporous products were obtained although at elevated calcination temperature. Delaminated sample with basal spacing value of 2.79 nm was obtained. Surface acidity of clay was enhanced by pillaring. Chemically sorbed pyridine Fourier …

Exploring The Ph Dependence Of Viologen Reduction By Alpha-Carbon Radicals Derived From Hcy And Cys, Dong Wang, William E. Crowe, Robert M. Strongin, Martha Sibrian-Vazquez

Chemistry Faculty Publications and Presentations

The colorimetric reaction of homocysteine (HCy) with a series of viologen salts suggests a linear correlation between the mid-point reduction potential of Hcy-derived α-carbon radicals and pH.

Structural Basis For Binding Specificity Between Subclasses Of Modular Polyketide Synthase Docking Domains, Tonia Buchholz, Todd W. Geders, Frank E. Bartley Iii, Kevin A. Reynolds, Janet L. Smith, David H. Sherman

Chemistry Faculty Publications and Presentations

Bacterial type I polyketide synthases (PKSs) assemble structurally diverse natural products of significant clinical value from simple metabolic building blocks. The synthesis of these compounds occurs in a processive fashion along a large multiprotein complex. Transfer of the acyl intermediate across interpolypeptide junctions is mediated, at least in large part, by N- and C-terminal docking domains. We report here a comprehensive analysis of the binding affinity and selectivity for the complete set of discrete docking domain pairs in the pikromycin and erythromycin PKS systems. Despite disconnection from their parent module, each cognate pair of docking domains retained exquisite binding selectivity. …

Hydroxyl Radical Is Produced Via The Fenton Reaction In Submitochondrial Particles Under Oxidative Stress: Implications For Diseases Associated With Iron Accumulation, Carin Thomas, Melissa M. Mackey, Amy A. Diaz, David P. Cox

All Faculty Scholarship for the College of the Sciences

Mitochondrial dysfunction and reactive oxygen species (ROS) are often implicated in diseases involving oxidative stress and elevated iron. As mitochondria produce ATP by oxidative phosphorylation, ROS by-products are generated from the electron transport chain. Although superoxide and hydrogen peroxide have been thoroughly investigated, little evidence documents hydroxyl radical (HO•) production in mitochondria. In order to determine whether HO• is generated under oxidative stress conditions by a Fenton-type mechanism, bovine heart submitochondrial particles were examined for HO• in the presence and absence of iron ligands, antioxidant enzymes and HO• scavengers. HO• was measured as 2,3- and 2,5-dihydroxybenzoic acid (DHBA), using HPLC …

Electrochemical And Optical Properties Of An Azo Dye Based Conducting Copolymer, Ati̇lla Ci̇haner, Fati̇h Algi

Turkish Journal of Chemistry

The electrochemical and optical properties of a novel conducting copolymer called poly(2,5'-dimethyl-[4-(2,5-di-thiophen- 2-yl-pyrrol-1-yl)-phenyl]azobenzene-co-(3,4-ethylenedioxythiophene)) (poly(1-co-EDOT)) are reported. Electrochemically synthesized poly(1-co-EDOT) based on the azo dye has a well-defined and reversible redox couple (0.37 V vs. Ag/AgCl) with good cycle stability. The copolymer film exhibits high conductivity (13 S/cm) as well as electrochromic behavior (magenta when neutralized and transmissive sky blue when oxidized). Furthermore, electro-optically active copolymer film has a low band gap of 1.79 eV with a \pi-\pi* transition at 555 nm.

Three-Component Process For The Synthesis Of Some Pyrrole Derivatives Under Microwave Irradiation, Farhad Hatamjafari, Nasser Montazeri

Turkish Journal of Chemistry

We report a short and efficient 3-component reaction for synthesis of a series of [1,2-b]pyrrole derivatives from ninhydrin, alkyl propiolates, and simple primary amines under solvent free and microwave irradiation. This method provides a new route to produce pyrrole derivatives in good to excellent yields.

4h-Pyran-4-One Derivatives:; Leading Molecule For Preparation Of Compounds With Antimycobacterial Potential, Demet Us, Ece Gürdal, Barkin Berk, Si̇nem Öktem, Tanil Kocagöz, Berrak Çağlayan, Işil Aksan Kurnaz, Di̇lek Demi̇r Erol

Turkish Journal of Chemistry

A series of 3-hydroxy-6-methyl-2-((4-substitutedpiperazin-1- yl)methyl)-4H-pyran-4-one structured compounds were synthesized by reacting 5-hydroxy-2-methyl-4H-pyran-4-one with suitable piperazine derivatives using Mannich reaction conditions. Antibacterial activities of the compounds for E. coli, S. paratyphi, S. flexneri, E. gergoviae, and M. smegmatis were assessed in vitro by using broth dilution for determination of the minimum inhibitory concentration (MIC). In addition, their inhibitory effects over DNA gyrase enzyme were evaluated using a DNA gyrase supercoiling assay. Among the synthesized compounds; compound 7 showed a 4 \mu g/mL MIC value for M. smegmatis, whereas the other compounds demonstrated moderate to high activity. Those tested in the supercoiling …

Mild And Efficient Iodination Of Aromatic Compounds With Trichloroisocyanuric Acid/I_2/Wet Sio_2 System, Batool Akhlaghinia, Marzieh Rahmani

Turkish Journal of Chemistry

Iodoarenes can be obtained using trichloroisocyanuric acid/I_2/wet SiO_2 system at room temperature with high yield in CH_2Cl_2.

Study Of The Polymerization Of Methyl Methacrylate Initiated By Thioxanthone Derivatives: A Magnetic Field Effect, Sevnur Keski̇n, Meral Aydin, Igor Khudyakov, Nergi̇z Arsu

Turkish Journal of Chemistry

Free radical photopolymerization of methyl methacrylate (MMA) initiated by 2-mercaptothioxanthone (TX-SH), thioxanthone-thioacetic acid (TXSCH_2COOH), and thioxanthone-carboxymethoxy acetic acid (TXOCH_2COOH) as so called one-component initiators was performed with and without an external magnetic field (MF). These initiators contain light-absorbing and electron/hydrogen-donating fragments in one molecule and do not require an additional hydrogen donor, and initiate the polymerization of MMA in the air. Polymerization experiments were performed in solutions with 3 different optical densities at \lambda 365 nm, where the photoinitiator absorbs. It was observed that application of MF leads to both larger conversion and higher molecular weight of the prepared PMMA, …

Investigation Of The Fuel Properties Of Biodiesel Produced Over An Alumina-Based Solid Catalyst, Nezahat Boz, Mi̇ray Kara, Oylum Sunal, Ertan Alpteki̇n, Nebahat Deği̇rmenbaşi

Turkish Journal of Chemistry

The present study investigated the transesterification process used in the production of canola oil methyl ester from canola oil and methanol over synthesized KF/Al_2O_3 catalysts. Different amounts of KF solution (15-65 wt. %) were impregnated into alumina. Loading 35 wt. % of KF into an alumina (35% KF/Al_2O_3) catalyst gave the maximum yield of 99.6% under the following reaction conditions: 60 °C, 8-h reaction time, 15:1 molar ratio of methanol/canola oil, and 3 wt. % of catalyst. The fuel properties of canola oil methyl ester were tested, including ester content, density, viscosity, flash point, copper strip corrosion, total and free …

A Novel Naphthoquinone Glycoside From Rubia Peregrina L., Ufuk Özgen, Cavi̇t Kazaz, Hasan Seçen, İhsan Çaliş, Maksut Coşkun, Peter J. Houghton

Turkish Journal of Chemistry

A phytochemical study was performed on the subterranean parts (roots and rhizomes) of Rubia peregrina. The substances were isolated from chloroform, ethyl acetate, and water soluble parts of the methanolic extract using several chromatographic techniques. 1-Hydroxy-2-methyl-9,10-anthraquinone (1), 1,3-dihydroxy-2-methyl- 9,10-anthraquinone (2), and 1,3-dihydroxy-2-methoxymethyl-9,10- anthraquinone (3) were isolated from the chloroform phase; and asperuloside (4), asperulosidic acid (5), rubiadin 3-O-\beta-primeveroside (6), lucidin 3-O-\beta -primeveroside (7), deacetylasperulosidic acid (8), liriodendrin (9), and a new naphthoquinone glycoside, 2-hydroxy-3-O-\beta-primeveroside naphthalene-1,4-dione (inkumoside, 10), from the aqueous phase. The structures of the compounds were elucidated by means of spectral analysis (^1H-NMR, ^{13}C-NMR, 2D-NMR--COSY, HMBC, HMQC-, EI-MS and …

Synthesis Of Methyl (E)-2',4''-Thiazachalcones And Their N-Alkyl Derivatives, Photochemistry With Theoretical Calculations And Antimicrobial Activities, Asu Usta, Ahmet Yaşar, Nuran Yayli, Şengül Alpay Karaoğlu, Nuretti̇n Yayli

Turkish Journal of Chemistry

A series of 9 new (E)-thiazachalcones (1-3), and their N-alkyl substituted derivatives (4-6), and stereoselective dimerization products (7-9) were synthesized, then tested for antimicrobial activity against all test microorganisms except Pseudomonas aeruginosa. The new compounds (1-6) without dimerization products (7-9) showed good antimicrobial property against Staphylococcus aureus, Listeria monocitogenes, and Enterococcus faecalis. The possible dimerization products of compounds (1-3) were calculated theoretically. Experimental and theoretical calculation showed that \delta-truxinic type dimer is the most stable isomer.

Bootstrap Enhanced N-Dimensional Deformation Of Space With Acoustic Resonance Spectroscopy, David John Link

University of Kentucky Doctoral Dissertations

Acoustic methods can often be used with limited or no sample preparations making them ideal for rapid process analytical technologies (PATs). This dissertation focuses on the possible use of acoustic resonance spectroscopy as a PAT in the pharmaceutical industry. Current good manufacturing processes (cGMP) need new technologies that have the ability to perform quality assurance testing on all products. ARS is a rapid and non destructive method that has been used to perform qualitative studies but has a major drawback when it comes to quantitative studies. Acoustic methods create highly non linear correlations which usually results in high level computations …

Pattern Recognition Integrated Sensing Methodologies (Prisms) In Pharmaceutical Process Validation, Remote Sensing And Astrobiology, Thaddaeus S. Hannel

University of Kentucky Doctoral Dissertations

Modern analytical instrumentation is capable of creating enormous and complex volumes of data. Analysis of large data volumes are complicated by lengthy analysis time and high computational demand. Incorporating real-time analysis methods that are computationally efficient are desirable for modern analytical methods to be fully utilized. The use of modern instrumentation in on-line pharmaceutical process validation, remote sensing, and astrobiology applications requires real-time analysis methods that are computationally efficient.

Integrated sensing and processing (ISP) is a method for minimizing the data burden and sensing time of a system. ISP is accomplished through implementation of chemometric calculations in the physics of …

A Lab To Stemulate Undergraduate Students Into Science, Technology, Engineering And Mathematics Majors, Nicole Lynn Speelman

Browse all Theses and Dissertations

The central focus is the development and implementation of a research/lab module for first year chemistry courses. Electrochemical techniques are utilized to study oxidation and reduction reactions of neurotransmitters with a poly(2,2'-Bithiophene) modified electrode. The goal is to excite students about chemistry and encourage them to continue studies in Science, Technology, Engineering, and Mathematics (STEM) during their undergraduate education. The lab module was created for Project REEL (Research Experiences to Enhance Learning) and will be illustrated with results typically obtained by students. The experiment is inquiry-based, which includes challenging questions students have to do collaboration and research to answer, as …

Design, Synthesis, And Characterization Of Novel Hydrophilic Fluorene-Based Derivatives For Bioimaging Applications, Dao Nguyen

Electronic Theses and Dissertations

In this work, hydrophilic fluorene-based derivatives that contain ethylene oxide substituents, have been synthesized and characterized for potential use as new fluorophores for bioimaging applications and for fluorescence sensing of heavy metals. Symmetrical and unsymmetrical fluorene derivatives based on structural types of acceptor-pi-acceptor, acceptor-pi-donor, and donor-pi-donor were characterized by TGA, UV-vis absorption, fluorescence emission, lifetime, anisotropy, and two-photon absorption (2PA) cross section. They were found to possess high thermal stability, high photostability, high fluorescence quantum yields, and generally large two-photon absorption cross sections, making them quite suitable for new probes in single-photon absorption and two-photon absorption fluorescence microscopy imaging. Novel …

Electrospray And Photoionization Mass Spectrometry For The Characterization Of Organic Matter In Natural Waters: A Qualitative Assessment, William C. Hockaday, Jeremiah M. Pucell, Alan G. Marshall, Jeffery A. Baldock, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

Fourier-transform ion cyclotron resonance mass spectrometry (MS) has demonstrated potential to revolutionize the fields of limnology and chemical oceanography by identifying the individual molecular components of organic matter in natural waters. The use of MS for this purpose is made possible by the electrospray technique which successfully ionizes polar, nonvolatile organic molecules. Another recently developed ion source, atmospheric pressure photoionization (APPI), extends MS capabilities to less polar molecules. This article presents early results on the application of APPI MS to natural organic matter. We compare APPI MS and electrospray MS data for dissolved organic matter from Lake Drummond (Virginia, USA). …

Merged Electrospray Ionization Mass Spectrometry, Jianan Dong

LSU Doctoral Dissertations

Ambient ionization allows the analysis of materials in their native environment without sample preparation by creating ions outside the mass spectrometer. The goal of this research was to develop new ambient ionization techniques for application to solids, liquids and particles under ambient conditions. Samples to be analyzed were directly merged with an electrospray of droplets, and then ionized and detected by a mass spectrometer. An ion trap mass spectrometer was modified with a nanoelectrospray source and configured for three experiments: merged electrospray ionization of dry particles, merged electrospray ionization of combustion products, and infrared laser desorption/ablation using electrospray for post-ionization. …

On-Line Laser Desorption/Ionization Mass Spectrometry, Damien A. Narcisse

LSU Doctoral Dissertations

Interfaces for on-line laser desorption/ionization mass spectrometry are presented in this dissertation. An on line laser desorption interface allows samples to be introduced directly into the mass spectrometer for high-throughput applications. For this research, a linear time of flight mass spectrometer was constructed with an ionization source designed to accept various laser desorption interfaces. A ball inlet interface was used for continuous analyte deposition at atmospheric pressure and vacuum ionization. A solvent-based cleaning system and a separate capillary for MALDI matrix delivery was utilized for continuous on line sampling with the ball inlet interface. Microfluidic devices were brought into contact …

Applying Scanning Probe Microscopy For The Investigation Of Molecular Self-Assembly Mechanisms And Properties Of Designed Nanomaterials, Algernon Tremayne Kelley

LSU Doctoral Dissertations

Scanning probe microscopy (SPM) for conducting surface characterizations of nanomaterials and molecular self-assembly processes is emerging as an important contribution in nanotechnology, especially towards the design of molecular electronic devices. Another area of importance is the characterization of the properties of nanomaterials for fundamental understanding of structure-function inter-relationships. Understanding the properties and behavior of molecules and finding approaches to control surface self-organization through nanolithography provides essential information for the development of workable applications for nanotechnology. This dissertation describes the methodologies of AFM for characterizing molecules and nanostructures produced with scanning probe lithography (SPL). Automated software for nanografting and nanoshaving produce …

Peptide Targeting Of Platinum Anti-Cancer Drug And Synthesis Of Water Soluble Monofunctional Pt(Ii) Complexes Useful For Biological Labeling, Margaret W. Ndinguri

LSU Doctoral Dissertations

Platinum has been used as an inorganic medicinal agent with various applications such as anti cancer agents. Several new targeted Pt(II) conjugates were synthesized having the NGR and LHRH targeting motif. The platinum conjugates bearing the NGR motif revealed selective delivery and destruction of cancer cells that had CD13 receptors compared to untargeted carboplatin drug. The development of targeted chemotherapeutic has opened a new approach for efficient delivery of antitumor toxins with minimal exposure to normal cells. Several peptide sequences are known to have the ability to target tumors, for instance NGR motif which home specifically in solid tumors and …

Amyloid Aggregation-Mitigating Peptides As Potential Alzheimer's Drugs, Cyrus Kipkurui Bett

LSU Doctoral Dissertations

Neuronal cytotoxicity observed in Alzheimer¡¦s disease (AD) is linked to the aggregation of £]-amyloid peptide (A£]) into toxic forms. Increasing evidence points to oligomeric species as the neurotoxic species compared to fibrils; disruption or inhibition of A£]ƒnself-assembly into oligomeric or fibrillar forms remains a viable therapeutic strategy to reduce A£] neurotoxicity. Amyloid aggregation mitigating peptides (AAMPs) were designed based on the A£]ƒn¡§hydrophobic core¡¨ A£]17-20, with C£\,£\-disubstituted amino acidsƒnƒv£\£\AAs) added into this core as disrupting agents. The number, distribution, and side chain functionality of £\£\AAs incorporated into the mitigator sequence was found influences the resultant aggregate morphology as indicated by ex-situ …

Microwave Assisted Solid-Supported Organic Synthesis: A Novel Methodology To Obtain 2,3-Disubstituted-1,4-Naphthoquinones, Israel Garcia-Martinez

Open Access Theses & Dissertations

This research focuses on the combinatorial solid phase organic synthesis (SPOS) of different bioactive compounds utilizing transition metal mediated reactions via microwave assisted organic synthesis (MAOS).

A microwave-assisted solid-supported Dötz benzannulation of chromium Fischer carbene complexes with various alkynes has been reported. The oxidative cleavage of the resulting resin-bound 1,4-naphthols affords 2,3-disubstituted-1,4-naphthoquinone derivatives in good to moderate yields with high purities. We demonstrated that solid phase organic synthesis of naphthoquinones via conventional heating is limited due to their long reaction times and high temperatures. The products decompose leading to low yields and purities.2 Microwave assisted synthesis of these naphthoquinones will …

Earth Field Magnetic Resonance Imaging And Paramagnetic Contrast Agents, Saideh Sadat Mortazavi

Open Access Theses & Dissertations

The goal of this research was to visualize the uptake of copper by plants to aid phyto-remediation research. The hypothesis was that regions of the plant with more copper will have an enhanced NMR signal using copper as a paramagnetic contrast agent.

As the name implies, Earth Field Magnetic Resonance Imaging (EFMRI) spectrometry uses a magnetic field 300,000 times weaker than a 600 MHz Nuclear Magnetic Resonance (NMR) spectrometer. Just like in conventional human MRI, this portable instrument is capable of recording one, two and three dimensional images though the sample size is much smaller.

The enhancement of signal was …

Pressure Induced Phase Transformation Of Sno2: An Ab Initio Constant Pressure Study, Daniel Tesfai Yehdego

Open Access Theses & Dissertations

The behavior of SnO2 under rapid hydrostatic pressures is studied using constant-pressure ab initio simulations. The rutile-type SnO2 gradually transforms into the CaCl2-type structure at 15 GPa. At a pressure of about 20 GPa, a phase transformation into a cubic fluorite-type structure is observed. The orthorhombic Pnma cotunnite-structured phase is observed above 150 GPa. The mechanisms of these phase transformations at the atomistic level are discussed.

Synthesis And Characterization Of Organic-Inorganic Colorants, Kiran A V Adiraju

Open Access Theses & Dissertations

New colorant materials have been found with the interaction of organic dyes and metal alkoxides. Changes in the hue are observed as indigo dye or thioindigo dyes are combined with the ASB (aluminum tri-secbutoxide), when compared to the original indigo or thioindigo dye, due to the binding and geometry change between dye and metal alkoxide. These dyes are combined with the ASB in two different methods of hydrolysis, namely in the air and in water. Similarly, when TTIP (Titanium tetraisopropoxide) is hydrolyzed using the sol gel process, along with the incorporation of thioindigo dye, hue changes were observed. X-ray diffraction …

Design, Synthesis And Study Of The Bridged And Cofacially-Arrayed Poly-P-Phenylene Molecular Wires, Matthew J. Modjewski

Master's Theses (2009 -)

Two novel series of bridged and cofacially-arrayed poly-p-phenylenes have been designed synthesized and studied. The bridged poly-p-phenylenes have been synthesized from a readily available diacetylenic precursor utilizing three high yielding steps, and their structures were determined by 1H/13C NMR spectroscopy as well as X-ray crystallography. The racemization barrier between the two atropoisomers was found to be ~12 Kcal mol-1; the versatility of the synthesis employed was extended to synthesis a triply bridged tetra-p-phenylene and a quadruply bridged penta-p-phenylene.

The cofacially-arrayed poly-p-phenylenes have shown that the X-ray crystal structures of the neutral compounds are largely dominated by C-H--π-interactions interactions while the …

Observed Superspin-Glass Behavior In Ni0.5zn0.5fe2o4 Nanoparticles, Antony Adair

Open Access Theses & Dissertations

In this investigation we seek to identify the magnetic behavior of Ni0.5Zn0.5Fe2O4 nanoparticles though AC-susceptibility and DC-magnetization measurements. Powder x-ray diffraction was performed to determine the purity and average diameter ( ~ 9nm) of the particles. Aditionally, structure was confirmed by comparison through the International Centre for Diffraction Data's Powder Diffraction File [52] (PDF # 08-0234).

Zero-field cooled and field cooled DC magnetization measurements (bifurcation and blocking temperature), as well as M(H) hysteresis (below and above the blocking temperature) lead us to initially suggest that the material may in fact be superparamagnetic. However, further investigation of the real AC susceptibility …