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Articles 61 - 90 of 1105
Full-Text Articles in Chemistry
Excitonic Coupling In Fluorene-Based Bichromophoric Systems: Vibrational Quenching And The Transition From Weak To Intermediate Coupling, Damian L. Kokkin, Neil Reilly, Maxim V. Ivanov, Rajendra Rathore, Scott A. Reid
Excitonic Coupling In Fluorene-Based Bichromophoric Systems: Vibrational Quenching And The Transition From Weak To Intermediate Coupling, Damian L. Kokkin, Neil Reilly, Maxim V. Ivanov, Rajendra Rathore, Scott A. Reid
Chemistry Faculty Research and Publications
Excimeric systems (i.e., excited dimers) have well served as model compounds for the study of the delocalization of electronic energy over weakly interacting chromophores. However, there remain relatively few isolated systems in which such interactions can be studied experimentally at a level to afford detailed comparisons with theory. In this Article, we examine a series of covalently and noncovalently linked dimers of fluorene, as a model aromatic chromophore, where the formation of excimers requires a π-stacked, cofacial orientation at van der Waals contact. Building upon a series of seminal prior studies that examined vibronic quenching of the excitation interaction in …
Application Of Nanodisc Technology To A Membrane-Bound P450: Functional Studies And Resonance Raman Studies On Cyp51a1, Yuanqi Jing
Dissertations (1934 -)
Membrane-bound cytochrome P450s are highly insoluble and tend to form aggregations in aqueous solution due to its hydrophobic N-terminal transmembrane anchor. The traditional methodology of studying membrane-bound proteins depends on the use of detergent; however, detergent solubilization of membrane P450s does not satisfy many criteria of biochemical and biophysical studies on membrane proteins. A well-developed Nanodisc technology has been proven to be an extraordinarily efficient method of studying membrane-bound P450s. The human sterol 14-demethylases (CYP51A1) are membrane-bound P450 enzymes that catalyze oxidative removal of the C32 methyl group of lanosterol by first forming an alcohol, then an aldehyde, and finally …
Kinetics Of Isotope-Labeled Pathways In The Ozone Forming Recombination Reaction, Elizaveta Grushnikova
Kinetics Of Isotope-Labeled Pathways In The Ozone Forming Recombination Reaction, Elizaveta Grushnikova
Dissertations (1934 -)
The ozone layer in Earth’s atmosphere is unique and plays a vital role in the development of life. Studying the mechanism behind ozone formation helps us understand the development of our planet’s atmosphere. We focus here on the anomalous mass-independent isotope effect.1 In 1981, Mauersberger et al.2 performed an experiment using weather balloons, resulting in the discovery of the anomalous isotope effect for ozone formation. Since then, other chemists have continued to investigate the theory behind this phenomenon. To understand the nature of the isotope effect, we must consider all stages of ozone formation. The basic reaction for ozone formation …
Reversible Dioxygen Binding To Co(Ii) Complexes With Noninnocent Ligands, Praveen Kumar, Laxmi Devkota, Maximilian C. Casey, Anne A. Fischer, Sergey V. Lindeman, Adam T. Fiedler
Reversible Dioxygen Binding To Co(Ii) Complexes With Noninnocent Ligands, Praveen Kumar, Laxmi Devkota, Maximilian C. Casey, Anne A. Fischer, Sergey V. Lindeman, Adam T. Fiedler
Chemistry Faculty Research and Publications
A series of mononuclear Co(II) complexes with noninnocent (redox-active) ligands are prepared that exhibit metal–ligand cooperativity during the reversible binding of O2. The complexes have the general formula, [CoII(LS,N)(TpR2)] (R = Me, Ph), where LS,N is a bidentate o-aminothiophenolate and TpR2 is a hydrotris(pyrazol-1-yl)borate scorpionate with R-substituents at the 3- and 5-positions. Exposure to O2 at room temperature results in one-electron oxidation and deprotonation of LS,N. The oxidized derivatives possess substantial “singlet diradical” character arising from antiferromagnetic coupling between an iminothiosemiquinonate (ITSQ•–) …
Mixed Quantum/Classical Theory For Collisional Quenching Of Pahs In The Interstellar Media, Bikramaditya Mandal, Carolin Joy, Alexander Semenov, Dmitri Babikov
Mixed Quantum/Classical Theory For Collisional Quenching Of Pahs In The Interstellar Media, Bikramaditya Mandal, Carolin Joy, Alexander Semenov, Dmitri Babikov
Chemistry Faculty Research and Publications
A computationally affordable methodology is developed to predict cross sections and rate coefficients for collisional quenching and excitation of large molecules in space, such as PAHs. Mixed quantum/classical theory of inelastic scattering (MQCT) is applied, in which quantum state-to-state transitions between the internal states of the molecule are described using a time-dependent Schrodinger equation, while the scattering of collision partners is described classically using mean-field trajectories. To boost the numerical performance even further, a decoupling scheme for the equations of motion and a Monte Carlo sampling of the initial conditions are implemented. The method is applied to compute cross sections …
Effect Of Ligands And Their Removal On The Au Nanoparticle-Catalyzed Reduction Of 4-Nitrophenol, Nicholas Langer, Ofer Kedem
Effect Of Ligands And Their Removal On The Au Nanoparticle-Catalyzed Reduction Of 4-Nitrophenol, Nicholas Langer, Ofer Kedem
Chemistry Faculty Research and Publications
The catalytic activity of gold nanoparticles (Au NPs) is strongly affected by the organic ligands coating them, which afford colloidal stability and are most commonly attached during the synthesis of the Au NPs. However, different ligands also produce Au NPs of different sizes and morphologies, complicating the study of the impact of the ligands themselves. Alternatively, postsynthetic ligand exchange risks incomplete exchanges and a mixed ligand shell, as well as colloidal instability. Here, Au NPs are immobilized on glass supports to afford truly ligand-free, solvent-stable Au nanoislands (NIs). The catalytic activity of Au NIs, uncoated and coated with a variety …
Enantioselective Synthesis Of Enantioisotopomers With Quantitative Chiral Analysis By Chiral Tag Rotational Spectroscopy, Mitchell D. Mills, Reilly E. Sonstrom, Zoua Pa Vang, Justin L. Neill, Haley N. Scolati, Channing T. West, Brooks H. Pate, Joseph R. Clark
Enantioselective Synthesis Of Enantioisotopomers With Quantitative Chiral Analysis By Chiral Tag Rotational Spectroscopy, Mitchell D. Mills, Reilly E. Sonstrom, Zoua Pa Vang, Justin L. Neill, Haley N. Scolati, Channing T. West, Brooks H. Pate, Joseph R. Clark
Chemistry Faculty Research and Publications
Fundamental to the synthesis of enantioenriched chiral molecules is the ability to assign absolute configuration at each stereogenic center, and to determine the enantiomeric excess for each compound. While determination of enantiomeric excess and absolute configuration is often considered routine in many facets of asymmetric synthesis, the same determinations for enantioisotopomers remains a formidable challenge. Here, we report the first highly enantioselective metal-catalyzed synthesis of enantioisotopomers that are chiral by virtue of deuterium substitution along with the first general spectroscopic technique for assignment of the absolute configuration and quantitative determination of the enantiomeric excess of isotopically chiral molecules. Chiral tag …
Synthesis And Characterization Of Biomimetic Co And Fe Complexes With Trispyrazolylborate Ligands, Praveen Kumar
Synthesis And Characterization Of Biomimetic Co And Fe Complexes With Trispyrazolylborate Ligands, Praveen Kumar
Dissertations (1934 -)
Numerous reactions of biological and environmental significance are catalyzed by dioxygenases that incorporate both atoms of O2 into the substrate. These enzymes require a transition-metal cofactor for activity, typically a mononuclear nonheme iron center, although dioxygenases with first-row transition metal ions (Mn, Co, Ni) have been discovered. This dissertation focuses on synthetic studies based on mononuclear dioxygenases found in bacterial pathways for the breakdown and assimilation of inert organic compounds, including human-generated pollutants. Such enzymes are essential for bioremediation technologies used to restore contaminated soils and groundwaters. While crystallographic studies have revealed the active-site structures of various types of dioxygenases, …
Properties And Behavior Of Tricarbonyl Manganese Scorpionate Complexes, Billy Shone
Properties And Behavior Of Tricarbonyl Manganese Scorpionate Complexes, Billy Shone
Master's Theses (2009 -)
Manganese tricarbonyl complexes have widely been studied for their ability to release carbon monoxide (CO) in the presence of light for potential applications in cancer therapy and in catalysis. Most studies focus on the kinetics and quantity of CO release and the overall impact on cell death. Far fewer studies identify the manganese intermediates and final products after decarbonylation. Identification of such products would be critical to improving reactivity and understanding potential (undesirable) side effects in future applications employing these CO releasing molecules (CORMs). Recently, nitrogen confused C-scorpionate ligands were introduced by the Gardinier group where a pyrazolyl ring is …
Uv- And Visible-Light Photopatterning Of Molecular Gradients Using The Thiol–Yne Click Reaction, Mark Mitmoen, Ofer Kedem
Uv- And Visible-Light Photopatterning Of Molecular Gradients Using The Thiol–Yne Click Reaction, Mark Mitmoen, Ofer Kedem
Chemistry Faculty Research and Publications
The rational design of chemical coatings is used to control surface interactions with small molecules, biomolecules, nanoparticles, and liquids as well as optical and other properties. Specifically, micropatterned surface coatings have been used in a wide variety of applications, including biosensing, cell growth assays, multiplexed biomolecule interaction arrays, and responsive surfaces. Here, a maskless photopatterning process is studied, using the photocatalyzed thiol–yne “click” reaction to create both binary and gradient patterns on thiolated surfaces. Nearly defect-free patterns are produced by first coating glass surfaces with mercaptopropylsilatrane, a silanizing agent that forms smoother self-assembled monolayers than the commonly used 3-mercaptopropyltrimethoxysilane. Photopatterning …
Intrinsic Photodynamic Study On Photocatalytic Materials, Wenhui Hu
Intrinsic Photodynamic Study On Photocatalytic Materials, Wenhui Hu
Dissertations (1934 -)
To relieve the global energy crisis and environmental pollution caused by the combustion of traditional fossil fuels, developing an environmental-friendly renewable energy to replace fossil fuel is urgent. Among the possible energy sources, solar energy has attracted numerous attentions because of the abundant storage. However, it is challenging to efficiently utilize and store solar energy. One attractive strategy to address this challenge is to convert solar energy to fuel through artificial photosynthesis (e.g. photocatalytic water splitting to generate H2). A technologically significant solar-driven water splitting system requires an efficient photocatalytic system that can not only effectively harvest light but also …
Synthesis And Characterization Of Enantioenriched Deuterated And Fluorinated Small Molecules, Mitchell D. Mills
Synthesis And Characterization Of Enantioenriched Deuterated And Fluorinated Small Molecules, Mitchell D. Mills
Master's Theses (2009 -)
The development of novel deuterated and fluorinated bioisosteres has significantly impacted the pharmaceutical and agricultural industry and created a growing demand for new synthetic methodology. Both deuterated and fluorinated small molecules exist at the forefront of drug discovery due to their unique ability to attenuate the pharmacokinetic properties of new and currently existing drugs. Selective, high-throughput methods for deuteration and fluorination are scarce in the literature, especially methods that introduce D or F atoms asymmetrically. Benzylic CH bonds are oftentimes key sites for enzymatic manipulation in metabolic processes, alteration of CH bonds to CD or CF bonds at the benzylic …
Highly Regioselective Copper-Catalyzed Transfer Hydrodeuteration Of Unactivated Terminal Alkenes, Albert Reyes, Emanuel Rivera Torres, Zoua Pa Vang, Joseph R. Clark
Highly Regioselective Copper-Catalyzed Transfer Hydrodeuteration Of Unactivated Terminal Alkenes, Albert Reyes, Emanuel Rivera Torres, Zoua Pa Vang, Joseph R. Clark
Chemistry Faculty Research and Publications
Catalytic transfer hydrodeuteration of unactivated alkenes is challenging because of the requirement that similar hydrogen and deuterium undergo selective insertion across a π-bond. We now report a highly regioselective catalytic transfer hydrodeuteration of unactivated terminal alkenes across a variety of heteroatom- or heterocycle-containing substrates. The base-metal-catalyzed reaction is also demonstrated on two complex natural products. Reaction studies indicate modular conditions that can also be extended to perform either an alkene transfer hydrogenation or transfer deuteration.
Molecular Dynamics On Quantum Annealers, Igor Gaidai, Dmitri Babikov, Alexander Teplukhin, Brian K. Kendrick, Susan M. Mniszewski, Yu Zhang, Sergei Tretiak, Pavel A. Dub
Molecular Dynamics On Quantum Annealers, Igor Gaidai, Dmitri Babikov, Alexander Teplukhin, Brian K. Kendrick, Susan M. Mniszewski, Yu Zhang, Sergei Tretiak, Pavel A. Dub
Chemistry Faculty Research and Publications
In this work we demonstrate a practical prospect of using quantum annealers for simulation of molecular dynamics. A methodology developed for this goal, dubbed Quantum Differential Equations (QDE), is applied to propagate classical trajectories for the vibration of the hydrogen molecule in several regimes: nearly harmonic, highly anharmonic, and dissociative motion. The results obtained using the D-Wave 2000Q quantum annealer are all consistent and quickly converge to the analytical reference solution. Several alternative strategies for such calculations are explored and it was found that the most accurate results and the best efficiency are obtained by combining the quantum annealer with …
Triple Oxygen Isotope Constraints On Atmospheric O2 And Biological Productivity During The Mid-Proterozoic, Peng Liu, Jingjin Liu, Aoshaung Ji, Christopher T. Reinhard, Noah J. Planavsky, Dmitri Babikov, Raymond G. Najjar, James F. Kasting
Triple Oxygen Isotope Constraints On Atmospheric O2 And Biological Productivity During The Mid-Proterozoic, Peng Liu, Jingjin Liu, Aoshaung Ji, Christopher T. Reinhard, Noah J. Planavsky, Dmitri Babikov, Raymond G. Najjar, James F. Kasting
Chemistry Faculty Research and Publications
Reconstructing the history of biological productivity and atmospheric oxygen partial pressure (pO2) is a fundamental goal of geobiology. Recently, the mass-independent fractionation of oxygen isotopes (O-MIF) has been used as a tool for estimating pO2 and productivity during the Proterozoic. O-MIF, reported as Δ′17O, is produced during the formation of ozone and destroyed by isotopic exchange with water by biological and chemical processes. Atmospheric O-MIF can be preserved in the geologic record when pyrite (FeS2) is oxidized during weathering, and the sulfur is redeposited as sulfate. Here, sedimentary sulfates from …
2d Covalent Organic Frameworks With An Incorporated Manganese Complex For Light Driven Carbon Dioxide Reduction, Denan Wang, Daniel Streater, Yun Peng, Jier Huang
2d Covalent Organic Frameworks With An Incorporated Manganese Complex For Light Driven Carbon Dioxide Reduction, Denan Wang, Daniel Streater, Yun Peng, Jier Huang
Chemistry Faculty Research and Publications
Covalent organic frameworks (COFs) have emerged as a novel class of crystalline porous photocatalytic materials due to their unique properties such as large surface area, tunable porosity, and rigid structure. In this work, we report the direct incorporation of a manganese CO2 molecular catalyst (MC) into COFs (Mn−TTA-COF) and the evaluation of its capability as photocatalyst for visible light driven CO2 reduction to form CO. We found that the photocatalytic activity of Mn−TTA-COF is quite low, which mainly results from the elimination of the CO ligand in the Mn MC upon light illumination, rendering its short duration in …
Synthesis And Pharmacological Studies Of Ph-Sensitive, Allosteric, And Bivalent Ligands As Modulators Of Gpcrs, Ricardo Rosas Jr.
Synthesis And Pharmacological Studies Of Ph-Sensitive, Allosteric, And Bivalent Ligands As Modulators Of Gpcrs, Ricardo Rosas Jr.
Dissertations (1934 -)
G protein-coupled receptors (GPCRs) are cell surface receptors that transduce extracellular signals into intracellular effector pathways via heterotrimeric G protein dependent and independent pathways. GPCRs are involved in numerous physiological processes and are implicated in pathological signaling for numerous diseases. Described herein are novel approaches towards the modulation of two specific Class A GPCRs: protease activated receptor 1 (PAR1) and the mu opioid receptor (MOR). Chapter 1 provides a general introduction to GPCRs, which includes structures, signaling, and putative heteromer formation. Chapters 2 and 5 provide background information on PARs and the MOR, respectively. Diverse approaches towards the modulation of …
Spectrumsdt: A Program For Parallel Calculation Of Coupled Rotational-Vibrational Energies And Lifetimes Of Bound States And Scattering Resonances In Triatomic Systems, Igor Gayday, Alexander Teplukhin, Jonathan Moussa, Dmitri Babikov
Spectrumsdt: A Program For Parallel Calculation Of Coupled Rotational-Vibrational Energies And Lifetimes Of Bound States And Scattering Resonances In Triatomic Systems, Igor Gayday, Alexander Teplukhin, Jonathan Moussa, Dmitri Babikov
Chemistry Faculty Research and Publications
We present SpectrumSDT – a program for calculations of energies and lifetimes of bound rotational-vibrational states below and scattering resonances above the dissociation threshold on a global potential energy surface of a triatomic system, which may include stable molecules, weekly-bound van-der-Waals complexes, and unbound atom + diatom scattering systems. Large-amplitude vibrational motion is treated explicitly using hyper-spherical coordinates. Three options for the rotational-vibrational interaction are supported: uncoupled (symmetric top rotor), partially coupled (to include interaction between several nearest states only) and full-coupled (vibrating asymmetric-top rotor). In addition to energies and lifetimes, SpectrumSDT is able to integrate ro-vibrational wave functions over …
Electronic Structures And Spectroscopic Signatures Of Diiron Intermediates Generated By O2 Activation Of Nonheme Iron(Ii)–Thiolate Complexes, Danushka M. Ekanayake, Dao Pham, Andrew L. Probst, Joshua R. Miller, Cordina V. Popescu, Adam T. Fiedler
Electronic Structures And Spectroscopic Signatures Of Diiron Intermediates Generated By O2 Activation Of Nonheme Iron(Ii)–Thiolate Complexes, Danushka M. Ekanayake, Dao Pham, Andrew L. Probst, Joshua R. Miller, Cordina V. Popescu, Adam T. Fiedler
Chemistry Faculty Research and Publications
The activation of O2 at thiolate–ligated iron(II) sites is essential to the function of numerous metalloenzymes and synthetic catalysts. Iron–thiolate bonds in the active sites of nonheme iron enzymes arise from either coordination of an endogenous cysteinate residue or binding of a deprotonated thiol-containing substrate. Examples of the latter include sulfoxide synthases, such as EgtB and OvoA, that utilize O2 to catalyze tandem S–C bond formation and S-oxygenation steps in thiohistidine biosyntheses. We recently reported the preparation of two mononuclear nonheme iron–thiolate complexes (1 and 2) that serve as structural active-site models of substrate-bound EgtB …
Dissecting Monomer-Dimer Equilibrium Of An Rnase P Protein Provides Insight Into The Synergistic Flexibility Of 5’ Leader Pre-Trna Recognition, Danyun Zeng, Ainur Abzhanova, Benjamin P. Brown, Nicholas J. Reiter
Dissecting Monomer-Dimer Equilibrium Of An Rnase P Protein Provides Insight Into The Synergistic Flexibility Of 5’ Leader Pre-Trna Recognition, Danyun Zeng, Ainur Abzhanova, Benjamin P. Brown, Nicholas J. Reiter
Chemistry Faculty Research and Publications
Ribonuclease P (RNase P) is a universal RNA-protein endonuclease that catalyzes 5’ precursor-tRNA (ptRNA) processing. The RNase P RNA plays the catalytic role in ptRNA processing; however, the RNase P protein is required for catalysis in vivo and interacts with the 5’ leader sequence. A single P RNA and a P protein form the functional RNase P holoenzyme yet dimeric forms of bacterial RNase P can interact with non-tRNA substrates and influence bacterial cell growth. Oligomeric forms of the P protein can also occur in vitro and occlude the 5’ leader ptRNA binding interface, presenting a challenge in accurately defining …
Covalent Immobilization Of Molecular Complexes On Metal-Organic Frameworks Towards Robust And Highly Efficient Heterogeneous Water Oxidation Catalysts, Xiangming Liang, Sizhou Yang, Junyi Yang, Wanjun Sun, Xiangyang Li, Baochun Ma, Jier Huang, Jiangwei Zhang, Lele Duan, Yong Ding
Covalent Immobilization Of Molecular Complexes On Metal-Organic Frameworks Towards Robust And Highly Efficient Heterogeneous Water Oxidation Catalysts, Xiangming Liang, Sizhou Yang, Junyi Yang, Wanjun Sun, Xiangyang Li, Baochun Ma, Jier Huang, Jiangwei Zhang, Lele Duan, Yong Ding
Chemistry Faculty Research and Publications
The major challenges to practical implementation of efficient noble metal based molecular water oxidation catalysts are their stability and recycle ability. Herein, noble metal Ru based molecular water oxidation catalysts were covalently anchored in MOFs through “amide bond” as bridges, which leads to the formation of high-efficiency and robust heterogeneous catalysts for water oxidation reaction. We show that the efficiency for CeIV-driven water oxidation was significantly enhanced by 120 times when the Ru molecules were immobilized on the frameworks of MIL-101(Cr). The relationship between recycle stability and the structure of the Ru complexes covalently anchored in MOFs was …
Catalytic Transfer Deuteration And Hydrodeuteration: Emerging Techniques To Selectively Transform Alkenes And Alkynes To Deuterated Alkanes, Zoua Pa Vang, Samuel J. Hintzsche, Joseph R. Clark
Catalytic Transfer Deuteration And Hydrodeuteration: Emerging Techniques To Selectively Transform Alkenes And Alkynes To Deuterated Alkanes, Zoua Pa Vang, Samuel J. Hintzsche, Joseph R. Clark
Chemistry Faculty Research and Publications
Increasing demand for deuterium-labeled organic molecules has spurred a renewed interest in selective methods for deuterium installation. Catalytic transfer deuteration and transfer hydrodeuteration are emerging as powerful techniques for the selective incorporation of deuterium into small molecules. These reactions not only obviate the use of D2 gas and pressurized reaction setups but provide new opportunities for selectively installing deuterium into small molecules. Commercial or readily synthesized deuterium donors are typically employed as easy-to-handle reagents for transfer deuteration and hydrodeuteration reactions. In this minireview, recent advances in the catalytic transfer deuteration and hydrodeuteration of alkenes and alkynes for the selective …
Copper-Catalyzed Transfer Hydrogenation, Deuteration, And Selective Transfer Hydrodeuteration Of Aryl Alkynes, Kiera Behlow
Copper-Catalyzed Transfer Hydrogenation, Deuteration, And Selective Transfer Hydrodeuteration Of Aryl Alkynes, Kiera Behlow
Master's Theses (2009 -)
Transfer hydrogenation utilizes a non-H2 source of hydrogen to reduce double and triple bonds, utilizing transition metal catalysts in addition to some organocatalysts. The use of earth-abundant first row transition metals with ligands that fine tune the reactivity of the catalyst allows for the selective reduction of unsaturated functionalities by utilizing cheap and ubiquitous hydrogen sources such as water and various alcohols. This precludes the need for highly flammable H2 gas, which is often used with heterogeneous catalysts that offer limited selectivity and functional group tolerability. Catalysts optimized for the transfer hydrogenation of the desired functionality can be implemented to …
Resonant Two-Photon Ionization And Velocity Mapped Ion Imaging Studies Of Aromatic Van Der Waals Complexes, James T. Makuvaza
Resonant Two-Photon Ionization And Velocity Mapped Ion Imaging Studies Of Aromatic Van Der Waals Complexes, James T. Makuvaza
Dissertations (1934 -)
The study of van der Waals complexes provides a means for understanding the nature and strength of non-covalent interactions. Non-covalent interactions including C-H/, C-H/O, C-H/N, C-H/F, halogen and chalcogen bonding are found in important intermediates that regulate chemical and biological processes in many forefront areas of science including molecular self-assembly, drug substrate interactions, supramolecular chemistry, crystal engineering and biochemistry. To better understand these interactions, laser spectroscopic techniques that include mass selected two color resonant two photon ionization (2CR2PI) and velocity mapped ion imaging spectroscopy in combination with complementary ab initio calculations were used to probe the electronic structure, geometries, and …
Efficient Method For An Approximate Treatment Of The Coriolis Effect In Calculations Of Quantum Dynamics And Spectroscopy, With Application To Scattering Resonances In Ozone, Igor Gayday, Dmitri Babikov
Efficient Method For An Approximate Treatment Of The Coriolis Effect In Calculations Of Quantum Dynamics And Spectroscopy, With Application To Scattering Resonances In Ozone, Igor Gayday, Dmitri Babikov
Chemistry Faculty Research and Publications
A numerical approach is developed to capture the effect of rotation–vibration coupling in a practically affordable way. In this approach only a limited number of adjacent rotational components are considered to be coupled, while the couplings to other rotational components are neglected. This partially coupled (PC) approach permits to reduce the size of Hamiltonian matrix significantly, which enables the calculations of ro-vibrational states above dissociation threshold (scattering resonances) for large values of total angular momentum. This method is employed here to reveal the role of the Coriolis effect in the ozone formation reaction at room temperature, dominated by large values …
In Situ Activated Co3–XNiXO4 As A Highly Active And Ultrastable Electrocatalyst For Hydrogen Generation, Kailu Guo, Yantao Wang, Junfeng Huang, Min Lu, Hua Li, Yong Peng, Pinxian Xi, Haoli Zhang, Jier Huang, Siyu Lu, Cailing Xu
In Situ Activated Co3–XNiXO4 As A Highly Active And Ultrastable Electrocatalyst For Hydrogen Generation, Kailu Guo, Yantao Wang, Junfeng Huang, Min Lu, Hua Li, Yong Peng, Pinxian Xi, Haoli Zhang, Jier Huang, Siyu Lu, Cailing Xu
Chemistry Faculty Research and Publications
The spinel Co3O4 has emerged as a promising alternative to noble-metal-based electrocatalysts for electrochemical water electrolysis in alkaline medium. However, pure Co3O4, despite having high activity in anodic water oxidation, remains inactive toward the hydrogen evolution reaction (HER). Here, a Ni-doped Co3O4(Co3–xNixO4) prepared by a simple method exhibits favorable HER activity and stability (>300 h, whether in 1 M KOH or the realistic 30 wt % KOH solution) after in situ electrochemical activation, outperforming almost all of the oxide-based electrocatalysts. More …
Synthetic And Mechanistic Studies Of Ruthenium Catalyzed C-C, C-H And C-N Bond Activation Reactions, Nuwan Asanka Pannilawithana
Synthetic And Mechanistic Studies Of Ruthenium Catalyzed C-C, C-H And C-N Bond Activation Reactions, Nuwan Asanka Pannilawithana
Dissertations (1934 -)
Transition metal-catalyzed selective CH, CC and CN bond activation reactions represent a challenging and synthetically important field in organic chemistry. In particular, transition-metal catalytic unreactive bond activation protocols are applicable in various stereoselective and atom economical complex organic molecule synthesis. Recently, significant research efforts have been made for utilizing catalytic CH and CC bond cleavage methods in the further development of commercially valuable pharmaceuticals and agrochemicals. The well-defined cationic Ru–H complex was found to be an effective catalyst for mediating the coupling reaction of 1,2-disubstituted indoles with α,β-unsaturated aldehydes and ketones, in which the regioselective Cα–Cβ activation of the carbonyl …
Toward Understanding The Origin Of Mass-Independent Fractionation In Sulfur Allotropes And In Ozone, Igor Gayday
Toward Understanding The Origin Of Mass-Independent Fractionation In Sulfur Allotropes And In Ozone, Igor Gayday
Dissertations (1934 -)
Mysterious isotope effects, found in atmospheric ozone, cannot be explained by the standard mass-dependent statistical model. Similar mass-dependent isotope effects were also uncovered in sulfur deposits older than 2 billion years. In an effort to pinpoint possible reasons of these isotope effects, we build a theoretical description of the recombination reactions in sulfur allotropes and in ozone. No potential energy surface exists for the sulfur allotropes, so electronic structure calculations are also required. Ab initio calculation of two dimensionally reduced (2D and 3D) models of the potential energy surface for the tetrasulfur molecule at CCSD(T)-F12 and MRCI levels of theory …
Development Of Mqct Method For Calculations Of Collisional Energy Transfer For Astrochemistry And Planetary Atmospheres, Bikramaditya Mandal
Development Of Mqct Method For Calculations Of Collisional Energy Transfer For Astrochemistry And Planetary Atmospheres, Bikramaditya Mandal
Dissertations (1934 -)
A mixed quantum/classical methodology and an efficient computer code, named MQCT, were developed to model molecular energy transfer processes relevant to astrochemical environments and planetary atmospheres and applied to several real systems. In particular, the rotational energy transfer in N2 + Na collisions was studied with the focus on quantum phase, differential cross-sections, and scattering resonances, and excellent agreement with full quantum results was found. For H2O + H2, detailed calculations were carried out with the focus on allowed vs. forbidden transitions between the ortho/para states of both collision partners. Again, excellent agreement with full quantum calculations was achieved. Calculations …
Design And Synthesis Of Selective Estrogen Receptor Agonists, Edward Edward Wetzel
Design And Synthesis Of Selective Estrogen Receptor Agonists, Edward Edward Wetzel
Dissertations (1934 -)
Estrogens are hormones that regulates many different physiological functions. A decline in estrogen leads to significant issues that decrease the quality of life. Past treatments of menopausal symptoms included the administration of estrogen. However, side effects such as an increased risk of breast cancer, made this an unattractive therapeutic option. When a new estrogen receptor (ERβ) was discovered, it provided new hope for hormone replacement therapy (HRT). ERβ was shown to inhibit tumor growth, whereas ERα regulates breast cancer proliferation in certain types of breast cancer. The therapeutic benefits of targeting ERβ are vast; herein we focus on the benefits …