Chemistry Commons^™

Analysis Of Mass Transfer Coefficient Of Co2 Absorbed By Two-Component Amine Mixture In A Packed Bed Column, Thanakornkan Limlertchareonwanit

Chulalongkorn University Theses and Dissertations (Chula ETD)

Nowadays, coal fired plant has an important role in generating energy all over the world. It affects to greenhouse gases effect (GHGs) and global warming. Carbon dioxide (CO2) is a product of coal combustion that is the amount of number one in the world. However, most of the CO2 usually remove from post-combustion process by chemical absorption which is Monoethanolamine (MEA). Anyway, MEA has a disadvantage such as low CO2 loading and corrosion. Therefore, this study needs to investigate the effect of the mass transfer for a new solvents, 2-(Methylamino)ethanol (2-MAE) and Dimethylaminoethanol (DMAE), compensate for the drawbacks of MEA …

Effect Of Cocatalyst Combination In Titanium-Based Ziegler-Natta Catalyst On Olefin Polymerization, Thanyaporn Pongchan

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research focused on effect of cocatalyst types (TEA, TnOA, and TEA+TnOA) on titanium-based Ziegler-Natta catalyst in olefin polymerization both in slurry and gas-phase systems. This study has been divided into four sections. The commercial titanium-based catalyst was selected to investigate effect of reaction temperature and oxidation state of titanium from ESR measurement on slurry ethylene and propylene polymerization in the first and the second parts, respectively. The commercial catalyst with TEA exhibited the highest activity in ethylene polymerization. However, divalent, and trivalent of titanium (Ti2+ and Ti3+) was active in ethylene polymerization to produce more polymer. Stability of Ti3+ …

A Theoretical And Experimental Study Of Charge Transport In Organic Thermoelectric Materials And Charge Transfer States In Organic Photovoltaics, Ashkan Abtahi

Theses and Dissertations--Physics and Astronomy

Applications of organic electronics have increased significantly over the past two decades. Organic semiconductors (OSC) can be used in mechanically flexible devices with potentially lower cost of fabrication than their inorganic counterparts, yet in many cases organic semiconductor-based devices suffer from lower performance and stability. Investigating the doping mechanism, charge transport, and charge transfer in such materials will allow us to address the parameters that limit performance and potentially resolve them. In this dissertation, organic materials are used in three different device structures to investigate charge transport and charge transfer. Chemically doped π-conjugated polymers are promising materials to be used …

Heparan Sulfate. A Ligand For Coordination Compounds., Eric Ginsburg

Theses and Dissertations

Heparan sulfate (HS), a type of glycosaminoglycan (GAG), has been identified as a ligand for interactions with polynuclear platinum complexes (PPCs). HS is involved in numerous biological processes, and often considered to be extracellular DNA. PPCs interact with HS through the formation of a “sulfate clamp”, where multiple anionic sulfate groups cluster around the cationic PPC. The masking of HS results in the inhibition of enzymatic activity, protein-HS interactions, and other biological processes. PPCs use HS proteoglycans as an method of cellular internalization. By targeting sulfated-GAGs, PPCs can offer precision medicine not currently observed with the FDA approved platinum therapies. …

Electrocatalytic Cathodes For Advanced Lithium–Sulfur Batteries, Ahmed Abdelkader

Theses and Dissertations

Energy demands are anticipated to increase in the next decades with the consumption of fossil fuels predicted to grow from the current levels. This will place an enormous burden on the non–renewable reserves of our energy sources and add to the preexisting environmental crisis with the emission of greenhouse gases like carbon dioxide (CO₂). Electrical energy storage (EES) is considered one of the most crucial needs of modern society to circumvent this crisis and potential applications include electric vehicles and devices, as well as storage systems for solar and wind sources.Lithium–ion batteries (LIBs) have proven to be …

Three Studies Of Research-Based Pedagogy In Physical Chemistry: Development Of A Zno Thin Film Experiment, Analysis Of Student Discourse By Graph Theory And Cognitive Engagement, Building A Physical Chemistry Faculty Network., Dilhara Liyanage

Theses and Dissertations

Three research projects, each focusing on a different aspect, development of a ZnO thin film experiment, student’s cognitive engagement behavior, and building of a faculty network, are presented in this dissertation.

In the first project, a physical chemistry laboratory experiment was developed to answer the question, “How do electrons move in a solid?”. The experiment structure follows the POGIL-PCL (Process Oriented Guided Inquiry Learning - Physical Chemistry Laboratory) model. Students begin by using the PhET “Quantum Bound States” animation to compare energy levels for single atoms to energy levels of a lattice containing many potential wells, and they incorporate that …

Synthesis Of Supported Metal Nanoparticles On High Surface Area Supports For Application In Energy Conversion And Heterogeneous Catalysis, Nazgol Norouzi

Theses and Dissertations

Precise control of metal nanoparticles’ size, composition, and dispersity over high surface area supports are highly desirable to address current challenges in energy storage and conversion as well as catalytic processes involving precious metals. Therefore, developing viable synthetic routes that enable new catalytic systems derived from inexpensive transition metals or limited use of precious metals is vital for clean energy applications such as fuel cells and rechargeable batteries or affordable drugs in the pharmaceuticals arena. In addition to metal components of heterogeneous catalysts, the catalyst support is an integral part of catalyst design as it can impart both physical stability …

Fabrication And Characterization Of Multicomponent Gradients Containing Weakly Acidic And Basic Functional Groups, Kallol Roy

Theses and Dissertations

Multicomponent synthetic chemical gradients containing amine (NH₂) and carboxylic acid (COOH) groups have been prepared on the silanol (Si-OH) containing a base-layer substrate by the controlled-rate infusion (CRI) method. The spatial variation of weakly acidic COOH and basic NH₂ functional groups on weakly acidic Si-OH surface was created in such a way that the two antagonist groups at high concentrations were in close proximity (aligned gradient) and were separated (opposed gradient). The difference in concentration of different components (acid, base, or silanol) along the length of aligned or opposed resulted in significantly different physicochemical properties …

Structure, Morphology And Composition-Property Elucidation Of Ni–Mo And Ni−Mo−P Nanocrystals For Water Splitting Reactions And Group Iv Alloy And Silicate Nanocrystals For Visible To Near Ir Optoelectronics, Ebtesam Hassan Abuelenein Eladgham

Theses and Dissertations

Abstract

Structure, Morphology and Composition-Property Elucidation of Ni–Mo and Ni−Mo−P Nanocrystals for Water Splitting Reactions and Group IV Alloy and Silicate Nanocrystals for Visible to Near IR Optoelectronics

by

Ebtesam Hassan Abuelenein Eladgham

A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University.

Advisor: Indika U Arachchige

Associate Professor, Department of Chemistry

Nanomaterials have gained a great attention because of their unique physical properties with size intermediate between molecular materials and extended solids. They have a large surface to volume ratio and display size tunable physical properties that was not …

Metal-Oxide Nanostructures Fabricated From Reactive Laser Ablation In Liquid, Mallory G. John

Theses and Dissertations

The development of metal-oxide nanostructures is a growing area due to their applications in diverse fields spanning energy conversion and storage, chemical manufacturing, and en- vironmental technology. This interest in catalytically active nanomaterials has prompted the synthesis and investigation of highly functionalized nanoparticles (NPs), including core- shell, silicate-stabilized, and bi- and multi-metallic nanocomposites. While wet-chemical synthesis methods of metal-oxide nanostructures have led to several morphologies, compositions, and shapes, these syntheses often require high temperatures, toxic solvents or reducing agents, and long reaction times.

Laser synthesis and processing of colloids (LSPC) encompasses both ‘top down’ and ‘bottom up’ approaches to synthesize …

Investigation Into The Reaction Profile Of A Bioinspired Nickel Complex, Denver Heitger

Theses and Dissertations

Metal complexes that can activate natural oxidants like H₂O₂ and O₂ have become a key research topic in many labs in hope of mimicking nature, by generating a bioinspired complex that can perform unique chemistry through green processes. To prepare the perfect catalyst, this has lead scientists to explore numerous avenues, including the use of both natural and artificial oxidants, to tease apart the reaction pathway taking place. A ligand system dear to the Lucas Lab (13-DOB) has been metalated with nickel, a cheap and earth abundant transition metal. Our bioinspired metal-(di)oxygen adducts can be formed …

Probing Vibrational Wave Packets In Organophoshorous Molecules Using Femtosecond Time-Resolved Mass Spectrometry (Ftrms), Derrick Ampadu Boateng

Theses and Dissertations

The study of organophosphorus and nitroaromatic compounds is essential due to their suitability as models for understanding the dynamics of radiation induce damage to DNA sugar-phosphate backbone, and the detection of chemical warfare agents as well as nitroaromatic explosives (such as TNT). The ultrafast dynamics of these polyatomic radicals were studied using femtosecond time-resolved mass spectrometry (FTRMS), a versatile method that is capable of monitoring the ultrafast dynamics of rapid dissociation in the gas phase after the removal of an electron. The method uses a technique called pump-probe, which makes use of two time-delayed laser pulses. In this work, the …

Towards A Greener Route To Blockbuster Statin Drugs: Harnessing The Power Of Biocatalysis And Integrating Cross-Coupling Catalysis In The Synthesis Of Rosuvastatin, Chanaka M. Amarasekarage

Theses and Dissertations

As global and political awareness about green and sustainable practices sharpens in the face of dramatic climate change and environmentally detrimental practices, one attractive approach is to harness the catalytic potential of enzymes. Thus influenced, our efforts focused on the development of an innovative chemoenzymatic route to widely prescribed Blockbuster statin drugs, specifically rosuvastatin. In this work, we engineered novel deoxyribose phosphate aldolase (DERA) variants via rationally designed site-directed mutagenesis to accept non-natural, less polar substrate, acrolein, along with acetaldehyde. Several of new mutants displayed elevated tolerance towards aldehydes and showed effective incorporation of acrolein into the unprecedented enzymatically-derived chiral …

Investigations Of Graphene-Supported Single-Atom Catalyst Model Ions In The Gas Phase, Michael Borrome

Theses and Dissertations

Recent developments in heterogeneous catalysis has led to the conception of single-atom catalysts (SACs), a class of catalysts based on isolated metal atoms anchored to a support scaffold. SACs are often much more reactive and can offer better selectivity when compared to nano-scale catalysts. In order to realize the full potential of SACs, a sound understanding of the underlying catalytic mechanisms is required. However, surface analysis tools can become less effective in studying catalytic mechanisms at the atomic scale. Mass spectrometry has proven to be a robust technique for studying organometallic catalytic mechanisms at the single-molecule level. Using mass spectrometry, …

Mechanistic Study Of C-H Activation By Iridium Complexes, Rozalie S G Corea

Theses and Dissertations

C-H activation is considered the “holy grail” of chemistry. Remote, selective C-H activation has many applications such as modifying precursors, adding complexity to molecules, and modifying pre- existing structures in a reduced number of steps. Previous work by Swift and Gronert identified an iridium(III) phenanthroline complex that can activate C-H bonds of cyclohexane. The objective of this dissertation is to study the mechanism and regioselectivity of this complex in common precursors, namely 1-butanol, 1-methoxybutane and butyl acetate.

The studies were carried out in the gas phase on a modified mass spectrometer. Selectively deuterated alcohol, ether and ester were used to …

Route Exploration And Synthesis Of The Reported Pyridone-Based Pdi Inhibitor Stk076545, Eric Greve, Sergey V. Lindeman, Christina Scartelli, Lin Lin, Robert Flaumenhaft, Chris Dockendorff

Chemistry Faculty Research and Publications

The enzyme protein disulfide isomerase (PDI) is essential for the correct folding of proteins and the activation of certain cell surface receptors, and is a promising target for the treatment of cancer and thrombotic conditions. A previous high-throughput screen identified the commercial compound STK076545 as a promising PDI inhibitor. To confirm its activity and support further biological studies, a resynthesis was pursued of the reported β-keto-amide with an N-alkylated pyridone at the α-position. Numerous conventional approaches were complicated by undesired fragmentations or rearrangements. However, a successful 5-step synthetic route was achieved using an aldol reaction with an α-pyridone allyl …

Nonheme Iron–Thiolate Complexes As Structural Models Of Sulfoxide Synthase Active Sites, Danushka M. Ekanayake, Anne A. Fischer, Maya E. Elwood, Alexandra M. Guzek, Sergey V. Lindeman, Cordina V. Popescu, Adam T. Fiedler

Chemistry Faculty Research and Publications

Two mononuclear iron(II)–thiolate complexes have been prepared that represent structural models of the nonheme iron enzymes EgtB and OvoA, which catalyze the O₂-dependent formation of carbon–sulfur bonds in the biosynthesis of thiohistidine compounds. The series of Fe(II) complexes reported here feature tripodal N₄ chelates (L^A and L^B) that contain both pyridyl and imidazolyl donors (L^A = (1H-imidazol-4-yl)-N,N-bis((pyridin-2-yl)methyl)methanamine; L^B = N,N-bis((1-methylimidazol-2-yl)methyl)-2-pyridylmethylamine). Further coordination with monodentate aromatic or aliphatic thiolate ligands yielded the five-coordinate, high-spin Fe(II) complexes [Fe^II(L^A)(SMes)]BPh …

Voltammetry And Spectroelectrochemistry Of Tcnq In Acetonitrile/Rtil Mixtures, Abderrahman Atifi, Michael D. Ryan

Chemistry Faculty Research and Publications

Understanding the solvation and ion-pairing interactions of anionic substrates in room-temperature ionic liquids (RTIL) is key for the electrochemical applications of these new classes of solvents. In this work, cyclic voltammetry and visible and infrared spectroelectrochemistry of tetracyanoquinodimethane (TCNQ) was examined in molecular (acetonitrile) and RTIL solvents, as well as mixtures of these solvents. The overall results were consistent with the formation of RTIL/acetonitrile nanodomains. The voltammetry indicated that the first electrogenerated product, TCNQ⁻, was not incorporated into the RTIL nanodomain, while the second electrogenerated product, TCNQ²⁻, was strongly attracted to the RTIL nanodomain. The visible …

Enhanced Light Harvesting Ability In Zeolitic Imidazolate Frameworks Through Energy Transfer From Cds Nanowires, Yixuan Zhou, Wenhui Hu, Sizhuo Yang, Jier Huang

Chemistry Faculty Research and Publications

Zeolitic imidazolate frameworks (ZIFs) represent a novel class of porous crystalline materials that have demonstrated potential as light harvesting materials for solar energy conversion. In order to facilitate their application in solar energy conversion, it is necessary to expand their absorption further into the realm of the solar spectrum. In this work, we report the incorporation of semiconductor cadmium sulfide nanowires (CdS NWs) into ZIF-67 (CdS@ZIF-67), where a broader region of the solar spectrum can be absorbed by CdS NWs and relayed to ZIF-67 through an energy transfer (EnT) process. Using steady-state emission and time resolved emission and absorption spectroscopy, …

Dynamic Evolution And Reversibility Of Single-Atom Ni(Ii) Active Site In 1t-Mos2 Electrocatalysts For Hydrogen Evolution, Brian Pattengale, Yichao Huang, Xingxu Yan, Sizhou Yang, Sabrina Younan, Wenhui Hu, Zhida Li, Sungsik Lee, Xiaoping Pan, Jing Gu, Jier Huang

Chemistry Faculty Research and Publications

1T-MoS₂ and single-atom modified analogues represent a highly promising class of low-cost catalysts for hydrogen evolution reaction (HER). However, the role of single atoms, either as active species or promoters, remains vague despite its essentiality toward more efficient HER. In this work, we report the unambiguous identification of Ni single atom as key active sites in the basal plane of 1T-MoS₂ (Ni@1T-MoS₂) that result in efficient HER performance. The intermediate structure of this Ni active site under catalytic conditions was captured by in situ X-ray absorption spectroscopy, where a reversible metallic Ni species (Ni⁰) …

Influence Of The Coriolis Effect On The Properties Of Scattering Resonances In Symmetric And Asymmetric Isotopomers Of Ozone, Igor Gayday, Elizaveta Grushnikova, Dmitri Babikov

Chemistry Faculty Research and Publications

Scattering resonances above dissociation threshold are computed for four isotopically substituted ozone species: ¹⁶O¹⁸O¹⁶O, ¹⁶O¹⁶O¹⁸O, ¹⁸O¹⁶O¹⁸O and ¹⁶O¹⁸O¹⁸O, using a variational method with accurate treatment of the rotation–vibration coupling terms (Coriolis effect) for all values of the total angular momentum J from 0 to 4. To make these calculations numerically affordable, a new approach was developed which employs one vibrational basis set optimized for a typical rotational excitation (J,Λ), to run coupled rotation–vibration calculations at several …

Singlet Fission In A Hexacene Dimer: Energetics Dictate Dynamics, Samuel N. Sanders, Elango Kumarasamy, Kealan J. Fallon, Matthew Y. Sfeir, Luis M. Campos

Publications and Research

Singlet fission (SF) is an exciton multiplication process with the potential to raise the efficiency limit of single junction solar cells from 33% to up to 45%. Most chromophores generally undergo SF as solid-state crystals. However, when such molecules are covalently coupled, the dimers can be used as model systems to study fundamental photophysical dynamics where a singlet exciton splits into two triplet excitons within individual molecules. Here we report the synthesis and photophysical characterization of singlet fission of a hexacene dimer. Comparing the hexacene dimer to analogous tetracene and pentacene dimers reveals that excess exoergicity slows down singlet fission, …

Molecular Dynamics Simulations Of Phase Behaviour And Structural Studies Of Guanidinium Triflate Ionic Liquid And Its Mixture With Water And N-Methyldiethanolamine For Carbon Dioxide Removal, Naimah Haron

Student Works (2020-2029)

Molecular dynamics (MDs) simulations with an all-atom force field have been carried out to understand the phase equilibrium behaviour of aqueous guanidinium triflate [gua][OTf] ionic liquid (IL) (binary system) at 440.15 K, as well as the phase equilibrium behaviour of N-methyl diethanolamine (MDEA) with aqueous [gua][OTf] IL (ternary system) at 298.15 K. This work further elaborated the understanding of absorption mechanism of carbon dioxide (CO2) into ternary system at 298.15 K. For binary system, the simulations measured changes in different physical properties such as density, structural, bonding properties (radial distribution function (RDF)), water clustering and hydrogen bonding) and dynamic property …

Phytochemical Investigations Of Goniothalamus Tapis And G. Tapisoides, And Kinetic Mechanism Studies Of Goniothalamin, Pei Theng Rosalind Kim

Student Works (2020-2029)

Phytochemical studies on two species of Annonaceae; Goniothalamus tapis and Goniothalamus tapisoides have been carried out. Isolation and purification of the crude extract of stem bark of G. tapis and G. tapisoides yielded seventeen compounds. G. tapis gave nine compounds; goniothalamin 1, isoaltholactone 41, 3-acetylisoaltholactone 151, cheliensisin A 22, garvensintriol 4, goniopyyprone 26, 7-epi-goniofufurone 49, stigmasterol 133 and β-sitosterol 134. Out of nine compounds, 3-acetyl-isoaltholactone 151 was identified as a new styryl-lactone. The skeleton is similar as the major compound, isoaltholactone 41. But 3-acetylisoaltholactone 151 have different functional group compared to hydroxyl group in isoaltholactone 41, which is acetyl group. …

Determination Of Samarium And Dysprosium Solubility, Seana Brennan

Theses and Dissertations (Comprehensive)

In recent years, the use of Rare Earth Elements (REE) has rapidly increased, resulting in numerous potential anthropogenic inputs to the environment. As a result, these metals are emerging as microcontaminants and pose a potential threat to aquatic life. However, the toxicity of REE are largely unknown due, in part, to the limited information on their chemical speciation. The purpose of this project was to gain an understanding of REE precipitate formation and solubility as the foundation for the development of the chemical equilibrium component of toxicity prediction models. Solubility experiments were conducted with Samarium, (Sm), a light REE, and …

Reconstructing Hydrologic Conditions And Metals Supplied By The Peace River To The Peace-Athabasca Delta, Jelle André Faber

Theses and Dissertations (Comprehensive)

The Peace-Athabasca Delta (PAD) in northern Alberta, Canada, is recognized internationally for its ecological, historical, and cultural significance. The delta is mostly within Wood Buffalo National Park, a UNESCO World Heritage Site, and is a Ramsar Wetland of International Importance. The construction of the WAC Bennett Dam (1967) and the Site C Dam (ongoing, 2024) on the Peace River, and expansion of the Alberta Oil Sands industry along the Athabasca River have raised concerns over water quantity and quality in the delta. When industry operations began, effective monitoring had not been implemented. Consequently, pre-industrial reference conditions are unknown and can …

Development Of Smartphone-Based Ecl Sensor For Dopamine Detection: Practical Approaches, Hyun J. Kwon, Elmer Rivera, Mabio R. Cohelo Neto, Daniel Marsh, Jonathan Swerdlow, Rodney Lee Summerscales, Padma P. Tadi Uppala

Faculty Publications

In this work, a compact, mobile phone-based ECL sensor apparatus was developed using the phone cameras, screen-printed electrodes (SPE), and mobile app for dopamine detection. Methods of DC voltage application for ECL reaction were comprehensively studied from the mobile phone itself or external power. Under optimized sensing conditions, with disposable carbon SPE and 20 mM coreactant tri-n-propylamine (TPrA), acceptable repeatability and reproducibility were achieved in terms of relative standard deviation (RSD) of intra- and interassays, which were 6.7 and 5.5%, respectively. The biochemical compound dopamine was measured due to its ECL quenching characteristics and its clinical importance. The …

Ratiometric Near-Infrared Fluorescent Probes For The Sensitive Detection Of Intracellular Ph And Bio-Thiols In Live Cells, Shuai Xia

Dissertations, Master's Theses and Master's Reports

In the past twenty years, fluorescence sensing and imaging based on fluorescent probes has been developed as an imperative technique due to the merits including excellent sensitivity, operational simplicity, instant time effectiveness and outstanding selectivity in the research areas such as mineralogy, gemology, biological medicine, materials and environmental engineering. Protons act as a significant role in a variety of pathological and physiological processes, and there are obvious differences in the pH among organelles: the pH in lysosomes is acid within the range of 4.5–5.5, whereas mitochondrial pH is basic that can be as high as 8.0. Abnormal intracellular pH is …

Exploring Substrate Specificity Of Fructose Transporters En Route To Glut Specific Probes For Biochemical And Biomedical Applications, Vagarshak Vigenovich Begoyan

Dissertations, Master's Theses and Master's Reports

Carbohydrate Transporters (GLUTs) are responsible for the transportation of sugars into the cell and have been of great interest in research for decades. Alterations or mutations that result in overexpression of GLUTs have been linked to a great number of diseases including, obesity, diabetes, and cancer. Differentiation between transporters has been shown to be incredibly difficult due to the highly conserved nature of the transporter structure, and thus specific targeting of transporters has proven a difficult challenge. Additionally, the GLUTs have been shown to high flexibility in their conformations, so it is difficult to determine what can or cannot pass …