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2015

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Articles 391 - 420 of 1428

Full-Text Articles in Chemistry

Synthesis Of Palladium And Palladium-Copper Nanostructures As Electrocatalysts, Haibin Wu Jul 2015

Synthesis Of Palladium And Palladium-Copper Nanostructures As Electrocatalysts, Haibin Wu

Graduate Theses and Dissertations

Pd and its alloys are alternatives of Pt as promising catalysts and electrocatalysts for many reactions. Size controlled synthesis of nanoparticles remains a major research subject, since smaller size particles show better catalytic performance. In this work, we developed a modified chemical wet method to prepare Pd and Pd-Cu nanostructures with uniform small size. Different sizes and shapes of Pd nanostructures were successfully synthesized by using the two reducing agents (i.e., L-ascorbyl-6-palmitate or phenylphosphinic acid). The reducing agents play a role to control the final morphologies and sizes of particles. The use of L-ascorbyl-6-palmitate favors to form irregular branch shapes …

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Crystal Structure Of Cis-2-(2-Carboxycyclopropyl)-Glycine (Ccg-Iii) Monohydrate, Sergey V. Lindeman, Nathaniel J. Wallock, William A. Donaldson Jul 2015

Crystal Structure Of Cis-2-(2-Carboxycyclopropyl)-Glycine (Ccg-Iii) Monohydrate, Sergey V. Lindeman, Nathaniel J. Wallock, William A. Donaldson

Chemistry Faculty Research and Publications

The title compound, C6H9NO4·H2O [systematic name: (αR,1R,2S)-rel-α-amino-2-carb­oxy­cyclo­propane­acetic acid monohydrate], crystallizes with two organic mol­ecules and two water mol­ecules in the asymmetric unit. The space group is P21 and the organic mol­ecules are enanti­omers, thus this is an example of a `false conglomerate' with two mol­ecules of opposite handedness in the asymmetric unit (r.m.s. overlay fit = 0.056 Å for one mol­ecule and its inverted partner). Each mol­ecule exists as a zwitterion, with proton transfer from the amino acid carb­oxy­lic acid group to …

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Towards A Global Model Of Spin-Orbit Coupling In The Halocarbenes, Silver Nyambo, Cyrus Karshenas, Scott A. Reid, Phalgun Lolur, Richard Dawes Jul 2015

Towards A Global Model Of Spin-Orbit Coupling In The Halocarbenes, Silver Nyambo, Cyrus Karshenas, Scott A. Reid, Phalgun Lolur, Richard Dawes

Chemistry Faculty Research and Publications

We report a global analysis of spin-orbit coupling in the mono-halocarbenes, CH(D)X, where X = Cl, Br, and I. These are model systems for examining carbene singlet-triplet energy gaps and spin-orbit coupling. Over the past decade, rich data sets collected using single vibronic level emission spectroscopy and stimulated emission pumping spectroscopy have yielded much information on the ground vibrational level structure and clearly demonstrated the presence of perturbations involving the low-lying triplet state. To model these interactions globally, we compare two approaches. First, we employ a diabatic treatment of the spin-orbit coupling, where the coupling matrix elements are written in …

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Progress Towards The Total Synthesis Of Yaku'amide A, Zhiwei Ma Jul 2015

Progress Towards The Total Synthesis Of Yaku'amide A, Zhiwei Ma

Theses and Dissertations

The synthetic progress towards yaku'amide A is described. The study leads to development of new synthetic methodologies. Base-free regioselective aminohydroxylation is convenient to deliver β-tert-hydroxyamino acids. A sequence consisting of alkylative esterification, Martin sulfurane mediated anti dehydration, a tandem azide reduction-O→N acyl transfer allows the rapid access of E- and Z-dehydroisoleucine-containing peptides from β-tert-hydroxyisoleucine derivatives. Those methods are effective in constructing complicated peptides and advanced subunits of yaku'amide A.

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Dna Origami Stabilized And Seeded With 4'-Aminomethyltrioxsalen For Improved Dna Nanowire Fabrication, Matthew Paul Mcdowell Jul 2015

Dna Origami Stabilized And Seeded With 4'-Aminomethyltrioxsalen For Improved Dna Nanowire Fabrication, Matthew Paul Mcdowell

Theses and Dissertations

A fast emerging technology in the microelectronics field is bottom-up self-assembly of computer circuitry. A promising method to develop nanoelectronic devices through bottom-up self-assembly is the implementation of DNA-based technologies. Using DNA to create nanoelectronic devices is advantageous because of its already well understood base-paring and annealing qualities. These base-pairing and annealing qualities can be used to design and construct DNA nanostructures called DNA origami. DNA origami are specially designed structures made from single stranded DNA. Short single stranded DNA oligonucleotides called staple strands attach to a large single stranded DNA called a DNA scaffold. DNA staple strands and DNA …

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Analyzing The Catalytic Role Of Active Site Residues In The Fe-Type Nitrile Hydratase From Comamonas Testosteroni Ni1, Salette Martinez, Rui Wu, Karoline Krzywda, Veronika Opalka, Hei Chan, Dali Liu, Richard C. Holz Jul 2015

Analyzing The Catalytic Role Of Active Site Residues In The Fe-Type Nitrile Hydratase From Comamonas Testosteroni Ni1, Salette Martinez, Rui Wu, Karoline Krzywda, Veronika Opalka, Hei Chan, Dali Liu, Richard C. Holz

Chemistry Faculty Research and Publications

A strictly conserved active site arginine residue (αR157) and two histidine residues (αH80 and αH81) located near the active site of the Fe-type nitrile hydratase from Comamonas testosteroni Ni1 (CtNHase), were mutated. These mutant enzymes were examined for their ability to bind iron and hydrate acrylonitrile. For the αR157A mutant, the residual activity (kcat = 10 ± 2 s−1) accounts for less than 1 % of the wild-type activity (kcat = 1100 ± 30 s−1) while the Km value is nearly unchanged at 205 ± 10 mM. On the …

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Study Of Photochemical Formation Of Hydroxyl Radical In Natural Waters, Luni Sun Jul 2015

Study Of Photochemical Formation Of Hydroxyl Radical In Natural Waters, Luni Sun

Chemistry & Biochemistry Theses & Dissertations

This dissertation mainly focuses on the sources of the hydroxyl radical (•OH) from photochemical reactions in natural waters, in particular from reactions involving dissolved organic matter (DOM). Firstly, an accurate method for estimating •OH formation rate during long-term irradiation was developed. It was observed that previous methods for measuring •OH formation rates in the natural waters, which were based upon sequentially determined cumulative concentrations of probe photoproducts, significantly underestimated actual •OH formation rates. It was found that the underestimation was mainly due to the degradation of the probe photoproducts and that only ‘instantaneous’ formation rates were appropriate for accurately estimating …

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Acoustic Attenuators Based On Porous Nanostructured Materials, Hongbing Lu, Ning Xiang, Nicholas Leventis, Chariklia Sotiriou-Leventis Jun 2015

Acoustic Attenuators Based On Porous Nanostructured Materials, Hongbing Lu, Ning Xiang, Nicholas Leventis, Chariklia Sotiriou-Leventis

Chemistry Faculty Research & Creative Works

The invention is directed to a porous, acoustic attenuating composition, wherein the composition comprises a nanostructured material and wherein the composition exhibits acoustic transmission loss ranging from 20 to 60 dB/cm thickness of the composition.

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Biological Activity Of Recently Discovered Halogenated Marine Natural Products, Gordon Gribble Jun 2015

Biological Activity Of Recently Discovered Halogenated Marine Natural Products, Gordon Gribble

Dartmouth Scholarship

This review presents the biological activity—antibacterial, antifungal, anti-parasitic, antiviral, antitumor, antiinflammatory, antioxidant, and enzymatic activity—of halogenated marine natural products discovered in the past five years. Newly discovered examples that do not report biological activity are not included.

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Nutrient Addition Effects On Tropical Dry Forests: A Mini-Review From Microbial To Ecosystem Scales, Jennifer S. Powers, Kristen K. Becklund, Maria G. Gei, Siddharth B. Iyengar, Rebecca Meyer, Christine S. O'Connell, Erik M. Schilling, Christina M. Smith, Bonnie G. Waring, Leland K. Werden Jun 2015

Nutrient Addition Effects On Tropical Dry Forests: A Mini-Review From Microbial To Ecosystem Scales, Jennifer S. Powers, Kristen K. Becklund, Maria G. Gei, Siddharth B. Iyengar, Rebecca Meyer, Christine S. O'Connell, Erik M. Schilling, Christina M. Smith, Bonnie G. Waring, Leland K. Werden

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Humans have more than doubled inputs of reactive nitrogen globally and greatly accelerated the biogeochemical cycles of phosphorus and metals. However, the impacts of increased element mobility on tropical ecosystems remain poorly quantified, particularly for the vast tropical dry forest biome. Tropical dry forests are characterized by marked seasonality, relatively little precipitation, and high heterogeneity in plant functional diversity and soil chemistry. For these reasons, increased nutrient deposition may affect tropical dry forests differently than wet tropical or temperate forests. Here, we review studies that investigated how nutrient availability affects ecosystem and community processes from the microsite to ecosystem scales …

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Synthesis Of Graphene Wrapped Li-Rich Layered Metal Oxide And Its Electrochemical Performance, Meng-Yan Hou, Ke Wang, Xiao-Li Dong, Yong-Yao Xia Jun 2015

Synthesis Of Graphene Wrapped Li-Rich Layered Metal Oxide And Its Electrochemical Performance, Meng-Yan Hou, Ke Wang, Xiao-Li Dong, Yong-Yao Xia

Journal of Electrochemistry

In present work, lithium-rich layered transition metal oxide (LLO) was synthesized by a co-precipitation method in combination with a solid-state reaction. The graphene wrapped Li-rich layered oxide composite (LLO/Gra) was obtained by sintering the LLO/GO composite at 300 oC for 30 min in an air. The morphologies and the electrochemical performances were characterized by means of SEM, TEM, XRD, XPS, EIS and charge/discharge tests. The results indicated that the LLOe particles were uniformly wrapped with graphene. The resulting material exhibited better rate capability than that of pristine LLO since the wrapped graphene demonstrated the enhanced electronic conductivity. Accordingly, the …

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Research Progress In Carbon Coating On Lifepo4 Cathode Materials For Lithium Ion Batteries, Ning Zhang, Yong-Chang Liu, Cheng-Cheng Chen, Zhi-Qiang Zhu, Zhan-Liang Tao, Jun Chen Jun 2015

Research Progress In Carbon Coating On Lifepo4 Cathode Materials For Lithium Ion Batteries, Ning Zhang, Yong-Chang Liu, Cheng-Cheng Chen, Zhi-Qiang Zhu, Zhan-Liang Tao, Jun Chen

Journal of Electrochemistry

Olivine-structured LiFePO4 has been received much attention because of its flat voltage profile, low cost, abundant material supply and better environmental compatibility. However, the poor electronic and ionic conductivities have limited its application in industry. One of the best methods to improve the electrochemical performance is carbon coating. In this review, we summarize the recent developments of LiFePO4/C cathode. Moreover, the different effects caused by coating methods and carbon sources, as well as the mechanism of carbon coating on the properties of LiFePO4/C are reviewed.

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Current Status And Prospect Of Cathode Materials For Lithium Sulfur Batteries, Lan Zhou, Ai-Shui Yu Jun 2015

Current Status And Prospect Of Cathode Materials For Lithium Sulfur Batteries, Lan Zhou, Ai-Shui Yu

Journal of Electrochemistry

Elemental sulfur has been extensively investigated as a promising candidate of cathode material for next generation lithium secondary batteries. However, some troublesome issues, such as the low electric conductivity of sulfur (5×10-30 S·cm-1) and the high solubility of lithium polysulfide intermediates in organic electrolytes, resulting in a low utilization of active material and a redox shuttling of dissolved polysulfide ions between the sulfur cathode and the lithium anode, which eventually leads to a deposition of insoluble and insulating Li2S2/Li2S on the electrode surface and a fast reduction in the specific capacity. …

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Enhancing Stability Of Pem Fuel Cell Catalysts Via Support Changing, Xiao-Hong Xie, Zi-Dong Wei Jun 2015

Enhancing Stability Of Pem Fuel Cell Catalysts Via Support Changing, Xiao-Hong Xie, Zi-Dong Wei

Journal of Electrochemistry

The Pt/C catalyst with highly dispersed Pt nanoparticles supported on carbon has been widely used as the state-of the-art catalyst in proton exchange membrane fuel cells (PEMFCs), while the durability of Pt/C is one of the major barriers for large-scale applications of PEMFCs. Thus, enhancing the stability of Pt/C has been a hot issue in this field. In this review, we summarize the recent progress in enhancing the catalyst stability in the view of support material. The future prospects of the PEMFCs catalyst should focus on adopting more stable supports or strengthening the interactions between Pt and supports.

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Lithium Air Batteries: Non-Aqueous And Hybrid Systems, Sheng-Fu Tong, Ping He, Xue-Ping Zhang, Shi-Yong Zhao, Hao-Shen Zhou Jun 2015

Lithium Air Batteries: Non-Aqueous And Hybrid Systems, Sheng-Fu Tong, Ping He, Xue-Ping Zhang, Shi-Yong Zhao, Hao-Shen Zhou

Journal of Electrochemistry

Developing energy storage devices and new materials, which match the requirements in electric vehicles (EVs) and hybrid electric vehicles (HEVs), is an effective way to balance the contradiction between the social development and the shortage of fossil energy and environment pollution. Rechargeable lithium-air (Li-air) batteries consisting of Li and oxygen as the anodic and cathodic reactants, respectively, have attracted much attention during the past decade due to their high theoretical specific energy. According to work conditions, the most studied types of Li-air batteries are non-aqueous, hybrid, and solid state electrolyte Li-air batteries. Challenges still exist in cathodes, anodes, electrolytes and …

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Research Status And Application Prospects Of Limnpo4 As A New Generation Cathode Material For Lithium-Ion Batteries, Lai-Fen Qin, Yong-Gao Xia, Li-Peng Chen, Hua-Sheng Hu, Feng Xiao, Zhao-Ping Liu Jun 2015

Research Status And Application Prospects Of Limnpo4 As A New Generation Cathode Material For Lithium-Ion Batteries, Lai-Fen Qin, Yong-Gao Xia, Li-Peng Chen, Hua-Sheng Hu, Feng Xiao, Zhao-Ping Liu

Journal of Electrochemistry

Olivine-structured lithium manganese phosphate (LiMnPO4) has the following advantages: excellent thermal stability, low cost, high safety and environmental benignity. Importantly, the theoretical energy density of LiMnPO4 is about 20% higher than that of commercialized LiFePO4 due to its higher Li+ intercalation potential of 4.1 V (vs. Li+/Li). Moreover, the high operating voltage of LiMnPO4 is compatible with present non-aqueous organic electrolytes of lithium-ion batteries. Therefore, LiMnPO4 is considered as a next generation cathode material for lithium-ion batteries. However, LiMnPO4 suffers from poor electronic conductivity and low lithium diffusivity, resulting in …

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Preparations And Applications Of Layered Carbon And Layered Carbon-Pbso4 Composite, Shu-Kai Zhang, Hao Zhang, Wei-Hua Xue, Jie Cheng, Wen-Feng Zhang, Gao-Ping Cao, Hai-Lei Zhao, Yu-Sheng Yang Jun 2015

Preparations And Applications Of Layered Carbon And Layered Carbon-Pbso4 Composite, Shu-Kai Zhang, Hao Zhang, Wei-Hua Xue, Jie Cheng, Wen-Feng Zhang, Gao-Ping Cao, Hai-Lei Zhao, Yu-Sheng Yang

Journal of Electrochemistry

The layered carbon materials (similar to graphene) have been synthesized by chemical vapor deposition (CVD) on the cheap catalyst (potassium or sodium carbonate substrate). The layered-carbon- lead sulfate (PbSO4) composite could be prepared by in situ chemical deposition based on the layered carbon. The XRD, SEM and TEM results showed that the layered carbon materials was amorphous carbon layer, and the composite was a compound made of fine lead sulfate grains and layered carbon. Thermogravimetric analysis determined the carbon content in the composite. Adding a certain amount of layered carbon or layered-carbon-PbSO4 composite into negative active materials …

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Pt/C Modified Proton Exchange Membrane For Improved Fuel Cell Performance, Zhi Cui, Chao Wang, Shui-Yun Shen, Feng-Jing Jiang, Jun-Liang Zhang Jun 2015

Pt/C Modified Proton Exchange Membrane For Improved Fuel Cell Performance, Zhi Cui, Chao Wang, Shui-Yun Shen, Feng-Jing Jiang, Jun-Liang Zhang

Journal of Electrochemistry

The property of proton exchange membrane greatly affects the performance of proton exchange membrane fuel cells (PEMFC). During the operation of a PEMFC, the water produced at the cathode, the water vapor from the humidified feed gas and the water migrated by electro-dragging will reach a balance in the membrane and determine the resistance of PEMFC, and thus affect the performance of PEMFC. Normally, the PEMFC performance strongly depends on the relative humidity of the feed gas, and the performance decreases at lower humidity as a result of lower proton conductivity of the membrane. In this paper, we proposed to …

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Preparation Of Zro2-Doped Nb/Pbo2 Electrode And Electrocatalytic Performance Of Methyl Orange Degradation, Li Zhang, Wen-Yan Dong, Tai-Lai Yang, Zhen-Hai Liang Jun 2015

Preparation Of Zro2-Doped Nb/Pbo2 Electrode And Electrocatalytic Performance Of Methyl Orange Degradation, Li Zhang, Wen-Yan Dong, Tai-Lai Yang, Zhen-Hai Liang

Journal of Electrochemistry

The zirconium oxide (ZrO2)-doped niobium based lead oxide (Nb/PbO2) electrode was prepared by electrodeposition. The microstructures and electrochemical properties of Nb/ZrO2+PbO2 electrode were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), linear sweep voltammetry, electrochemical impedance spectroscopy and cyclic voltammotry. In addition, the Nb/PbO2 electrode was used as an anode for the electrochemical degradation of methyl orange (MO). Results revealed that the ZrO2 doping made the Nb/PbO2 electrode surface denser and rougher with smaller sized crystal particles, which increased the specific surface area and enhanced the electrocatalytic activity of the …

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Electrochemical Mass Spectrometric Study Of Lithium-Oxygen Batteries, Xin-Xiu Yan, Li-Po Ma, Zhang-Quan Peng Jun 2015

Electrochemical Mass Spectrometric Study Of Lithium-Oxygen Batteries, Xin-Xiu Yan, Li-Po Ma, Zhang-Quan Peng

Journal of Electrochemistry

Mass Spectrometry, coupled with electrochemistry, is a powerful research tool to study mechanisms for a broad range of electrode reactions by identifying and quantifying reaction products and intermediates. In this review, we summarize the recent advances in the Li-O2 battery researches offered by electrochemical mass spectrometry based on our group investigations. These include the research progresses in electrolytes, cathode materials (electrocatalysts), and parasitic reactions, i.e., the key issues associated with Li-O2 research. In addition, we also discuss the effects of irreversible side reactions involved in battery systems on charge and discharge processes.

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Electrolytes For Lithium And Lithium-Ion Batteries, Zong-Rang Zhang Jun 2015

Electrolytes For Lithium And Lithium-Ion Batteries, Zong-Rang Zhang

Journal of Electrochemistry

This is an up-to-date book published by Springer last year and focuses on the field of the electrolytes for lithium and lithium-ion batteries. A brief introduction and review of this book are given in this paper. The main contents of this book are introduced briefly in the order of ten different chapters along with a short review of recent progress in those fields.

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Synthesis And Characterization Of Conjugated/Cross-Conjugated Benzene-Bridged Boron Difluoride Formazanate Dimers, Stephanie M. Barbon, Jacquelyn T. Price, Umesh Yogarajah, Joe Gilroy Jun 2015

Synthesis And Characterization Of Conjugated/Cross-Conjugated Benzene-Bridged Boron Difluoride Formazanate Dimers, Stephanie M. Barbon, Jacquelyn T. Price, Umesh Yogarajah, Joe Gilroy

Chemistry Publications

One of the most common strategies for the production of molecular materials with optical properties in the far-red/near-IR regions of the electromagnetic spectrum is their incorporation into dimeric architectures. In this paper, we describe the synthesis and characterization (1H, 11B, 13C and 19F NMR spectroscopy, IR and UV-Vis absorption and emission spectroscopy, mass spectrometry and X-ray crystallography) of the first examples of boron difluoride (BF2) formazanate dimers. Specifically, the properties of meta- and para-substituted benzene-bridged dimers p-10 and m-10 were compared to closely related boron difluoride triphenyl formazanate complex …

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The Electronic Structure Of The Pyranopterin Dithiolene Cofactor And Radical Reporters Of Excited State Interactions, Benjamin William Stein Jun 2015

The Electronic Structure Of The Pyranopterin Dithiolene Cofactor And Radical Reporters Of Excited State Interactions, Benjamin William Stein

Chemistry and Chemical Biology ETDs

Crystal structures of multiple molybdenum enzymes clearly demonstrate interesting structural distortions involving the pyranopterin dithiolene. These distortions can be correlated with pyranopterin oxidation state through the use of DFT geometry optimized structures of the possible oxidation states, and these are correlated with enzyme family. The potential role of the pyranopterin dithiolene in electron transfer in the varied enzyme familes has been explored through the use of non-equilibrium Green's function (NEGF) electron transport calculations. These calculations demonstrate clear differences in electron transport behavior as a function of pyranopterin oxidation state. The Jahn-Teller effect can strongly impact the geometric and electronic structures …

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Aerobic Copper-Catalyzed O-Methylation With Methylboronic Acid, Clare E. Jacobson, Noella Martinez-Muñoz, David J. Gorin Jun 2015

Aerobic Copper-Catalyzed O-Methylation With Methylboronic Acid, Clare E. Jacobson, Noella Martinez-Muñoz, David J. Gorin

Chemistry: Faculty Publications

The oxidative coupling of alkylboronic acids with oxygen nucleophiles offers a strategy for replacing toxic, electrophilic alkylating reagents. Although the Chan–Lam reaction has been widely applied in the arylation of heteroatom nucleophiles, O-alkylation with boronic acids is rare. We report a Cu-catalyzed nondecarboxylative methylation of carboxylic acids with methylboronic acid that proceeds in air with no additional oxidant. An isotope-labeling study supports an oxidative cross-coupling mechanism, in analogy to that proposed for Chan–Lam arylation.

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Building An Undergraduate Cohort In High Altitude Ballooning, Mike Davis Jun 2015

Building An Undergraduate Cohort In High Altitude Ballooning, Mike Davis

2017 Academic High Altitude Conference

City Colleges of Chicago (CCC), in partnership with DePaul University and the Illinois Space Grant Consortium, has recently been awarded a grant from NASA to develop a research and education program in high-altitude ballooning. The project builds on the Chicago Initiative for Research and Recruitment in the Undergraduate Sciences (CIRRUS) model of undergraduate research and community college/four year college collaborative projects, a successful NSF-funded collaboration between DePaul and CCC. The project has four goals: (1) initiate a year-round undergraduate research program to recruit promising community college students into the STEM disciplines, (2) provide tuition support and fellowships to support student …

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Electrochemical Investigation Of Homogenous Species At An Electrode Interface, Christopher Alan Larsen Iii Jun 2015

Electrochemical Investigation Of Homogenous Species At An Electrode Interface, Christopher Alan Larsen Iii

Chemistry and Chemical Biology ETDs

CO2 reduction is a pressing problem worldwide, and one obstacle in the electrochemical conversion of CO2 to more useful C1 products such as methanol and formic acid is the kinetic barrier known as overpotential. The overpotential of rearranging the nuclei in CO2 to accommodate electron transfer can be lowered by pre-bending the CO2 molecule in an adduct-mediated complex. The work presented in Part I utilizes a combination of hard and soft donors on pincer-like ligands to effect the bending of CO2 prior to electrochemical reduction. A large majority of the work consists of using …

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Theory, Multiscale Simulations, And Experiments On Mesoscale Multifunctional Systems, Lance Edward Edens Jun 2015

Theory, Multiscale Simulations, And Experiments On Mesoscale Multifunctional Systems, Lance Edward Edens

Chemistry and Chemical Biology ETDs

Computational simulations use theoretical models to reproduce, as accurately as possible, the observed real-world behavior of complex structures. Guided by experimental observations, many multiscale/coarse-grained simulations seek to explore increasingly complicated systems. Here, a multiscale/coarse-grained simulation program (called TM2) is developed with applications to 1) properties and mechanisms of DNA and DNA polymerases, and 2) adhesion between whole bacterial cells and patterned surfaces. Results from the bacterial adhesion application form a part of a larger collaborative effort aimed at creating multifunctional, controllable surfaces to capture and kill pathogenic bacteria. The application of TM2 is first demonstrated by a coarse-grained model for …

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Spectroscopic And Computational Studies Of Molybdenum Enzymes And Models, Chao Dong Jun 2015

Spectroscopic And Computational Studies Of Molybdenum Enzymes And Models, Chao Dong

Chemistry and Chemical Biology ETDs

In this dissertation spectroscopic methods such as electronic absorption (EAS), resonance Raman (rRaman), electron paramagnetic resonance (EPR), and MCD spectroscopies have been used in combination with DFT calculations for the interpretation of experimental results. These methods have been used to investigate the molybdenum coordination environment in enzymes and model complexes. Xanthine oxidase (XO), one of the canonical molybdenum enzyme families, hydroxylizes heterocyclic substrates by inserting an oxygen atom from molybdenum-activated water into a substrate C-H bond. This generates reducing equivalents that pass through two iron sulfur clusters and then to FAD, where oxidation of the FAD takes place. In this …

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Study Of Novel Synthetic Methodologies For Indolyl Derivatives And Beta-Fluoroenals, Xiaobei Chen Jun 2015

Study Of Novel Synthetic Methodologies For Indolyl Derivatives And Beta-Fluoroenals, Xiaobei Chen

Chemistry and Chemical Biology ETDs

One of the central goals in modern organic synthesis is to develop efficient synthetic strategies for the preparation and study of complex molecules possessing interesting structural, biological, and physical properties. Toward this end, my Ph. D. work focuses on the development of novel synthetic methodologies for the facile construction of synthetically and biologically significant molecular architectures. The tert-prenylated indoles and indolines are widely present in a large collection of natural products and biologically active compounds. Although significant efforts have been made on the development of efficient methods to prepare these intriguing molecular architectures, few methods have been explored to introduce …

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Synthesis Of Tetrahydro-1,2-Oxazines And Pyrrolidines Via Cycloadditions Of Donor-Acceptor Cyclobutanes And Nitrosoarenes, Naresh Vemula, Brian L Pagenkopf Jun 2015

Synthesis Of Tetrahydro-1,2-Oxazines And Pyrrolidines Via Cycloadditions Of Donor-Acceptor Cyclobutanes And Nitrosoarenes, Naresh Vemula, Brian L Pagenkopf

Chemistry Publications

During efforts to expand the scope of Lewis-acid-catalyzed [4+2] cycloaddition between donor–acceptor cyclobutanes and nitrosoarenes, an unexpected formation of pyrrolidine products was discovered when 50 mol-% of MgI2 was used as a Lewis acid. It was also observed that the electronics of the nitrosoarene and judicious selection of the Lewis acid catalyst have a profound effect on the regioselectivity of the reaction.

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