Chemistry Commons^™

Hierarchical Templates And Their Application To Multimodal Porous Materials Fabrication, Bo Zhao

Theses and Dissertations

Hierarchical materials offer great promise for high-performance sensors and catalysis carriers. Well-defined hierarchically porous materials are promising candidates for a wide range of applications relating to biosensors, separations, drug delivery, surface-enhanced Raman scattering (SERS), etc. Research on synthetic methodologies is expanding. However, fabrication of hierarchical porous structures with tunable pore dimension and shape, controllable pore distribution and interconnectivity is still a challenging task in materials science. One of the main tasks of this work is to establish a facile and reliable approach of making well-defined hierarchically porous materials. Then, based on those multimodal porous structures, different functions and applications can …

Dynamics Of The Solvent Exchange Reaction Of Weakly Bound Organic Solvents To Group 6 Transition Metal Carbonyls And The Molybdenum Hexacarbonyl Mediated Pauson-Khand Reaction, Richard J. Gates

Theses and Dissertations

Many organometallic reactions are solvent-dependent, suggesting solvent molecules interact with reaction intermediates. Studies of the solvent exchange reaction of group 6 transition metal carbonyls with moderately binding ligands have provided insight into these interactions, however, studies of the mechanism for this reaction with weakly binding ligands have not been performed. Experiments were conducted on the nanosecond time scale in methylcyclohexane over the temperature range of 4 to 44 °C using Step Scan FTIR (SS FTIR) spectroscopy with weakly binding ligands benzene and mesitylene. Upon photolysis of the metal hexacarbonyls, the kinetically favored product (M(CO)5(solv)), decays following pseudo-first-order kinetics to the …

Identification And Quantification Of Protein Carbonylation By Mass Spectrometry, Qingyuan Liu

Theses and Dissertations

Accumulated evidence indicates oxidative stress plays important roles in disease and aging. Under oxidative stress, lipid peroxidation (LPO) leads to reactive carbonyl species (RCS) that can modify a wide range of biomolecules including protein, DNA and carbohydrate. In this dissertation, we investigate the modification of two model proteins, human serum albumin (HSA) and aconitase (ACO), by the LPO-relevant a, b-unsaturated aldehydes, acrolein (ACR) and 4-hydroxy-2-nonenal (HNE). The investigation is focused on the characterization and quantification ACR and HNE addition to the model proteins. A correlation between HNE modification and ACO activity is also determined. These results provide insights into the …

Vapor-Liquid Phase Equilibria Using Monte Carlo Wang-Landau Simulations, Tsvetan Aleksandrov

Theses and Dissertations

The experimental determination of the critical point of metals is inherently connected with difficulties of measuring large temperatures and pressures. On the other hand, that of straight alkane chains larger than ten carbon atoms and branched chains larger than eight atoms is burdensome due to decomposition of the molecules while in the vapor phase. Therefore molecular simulations stand as an appropriate alternative for determining the critical point and phase coexistence properties of these fluids. Most simulation methods that are apt for this task rely on particles insertion and deletion moves that can significantly complicate the simulation, since high density in …

Biochemical Actions Of A Novel Cis-Terpenone, Lin Zhang

Theses and Dissertations

Abstract BIOCHEMICAL ACTIONS OF A NOVEL CIS-TERPENONE By Lin Zhang, Ph.D. A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University. Virginia Commonwealth University, 2012 Director: Qibing Zhou, Ph.D Assistant Professor Department of Chemistry

Quinone methides are reactive species due to their electrophilicity, and natural quinone methide analogs have broad biological activities. Based on known actions of cytochrome P450 enzymes, we hypothesized that trans-terpenones can be metabolized in cells to form a cascade of metabolite products, which may be biologically active due to the generation of quinine and quinone methide …

Design And Synthesis Of Cationic Steroid Antimicrobial Compounds, Synthesis Of Glycolipids Recognized By Natural Killer T Cells And Development Of Tlr-1, Tlr-6 Heterodimer Binders And Studies Of Their Immunology Activities, Yanshu Feng

Theses and Dissertations

Cationic steroid antimicrobial agents (CSAs) are a family of bile acid derivatives. These compounds are amphiphilic and mimic endogenous antimicrobial peptides. The antimicrobial activities of CSA-13 have been investigated and due to portent bactericidal activities and low toxicity, a large amount of CSA-13 is demanded for clinic trails and other antimicrobial applications. During our studies, we optimized the synthetic route of CSA-13, so that it can be prepared at the kilogram, even in tons scale. We investigated three routes and one of them is suitable for industry, because only recrystallization is needed in the synthesis. Natural killer T cells (NKT …

Influence Of Weak Interactions On Supramolecular Binding: Characterization Of Cucurbituril Complexes With Alkylmonoammonium Ions Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, Ruijan Shi

Theses and Dissertations

This thesis focuses on using mass spectrometry-based techniques for characterizing the structure and behavior of cucurbituril complexes in the gas phase. Both solvent and counter ion effects can be completely eliminated in the gas phase and the intrinsic interactions in the system are directly shown in the experimental results. Chapter 1 introduces the structures, properties and host-guest chemistry of cucurbituril, and FTICR mass spectrometry including instrumentation, performance and working principles. Two mass spectrometry-based methods for supramolecular characterization, sustained off-resonance irradiation collision induced dissociation (SORI CID) and ion molecule equilibrium measurements, are also discussed in this chapter. Chapter 2 characterizes the …

Mechanism Of G Protein Beta-Gamma Assembly Mediated By Phosducin-Like Protein 1, Chun Wan Jeffrey Lai

Theses and Dissertations

G-protein coupled receptor signaling (GPCR) is essential for regulating a large variety of hormonal, sensory and neuronal processes in eukaryotic cells. Because the regulation of these physiological responses is critical, GPCR signaling pathways are carefully controlled at different levels within the cascade. Phosducin-like protein 1 (PhLP1) can bind the G protein βγ dimer and participate in GPCR signaling. Recent evidence has supported the concept that PhLP1 can serve as a co-chaperone of the eukaryotic cytosolic chaperonin complex CCT/TRiC to mediate G βγ assembly. Although a general mechanism of PhLP1-mediated G βγ assembly has been postulated, many of the details about …

Synthesis And Characterization Of Highly Porous Borazine-Linked Polymers Via Dehydrogenation/Dehydrocoupling Of Borane-Amine Adducts And Their Applications To Gas Storage, Karl Jackson

Theses and Dissertations

A new class of porous polymers has been designed and successfully synthesized by thermal dehydrogenation of several polytopic arylamine-borane adducts and has been designated Borazine-Linked Polymers (BLPs). The polymers reported are constructed of linear, triangular, and tetrahedral amine building units to form 2D and 3D frameworks. The boron sites of the pores are aligned with hydrogen atoms contrasted with the recently reported halogenated BLPs which consist of pore channels aligned with bromine or chlorine atoms. One of the reported BLPs, BLP-2(H), was proven to be crystalline by PXRD, matching the experimental pattern to theoretical patterns calculated from modeled structures. BLPs …

Designed Synthesis Of Halogenated Borazine-Linked Polymers And Their Applications In Gas Storage And Separation, Thomas Reich

Theses and Dissertations

The synthesis of highly porous organic polymers with predefined porosity has attracted considerable attention due to their potential in a wide range of applications. Of particular interest in porous organic polymers is their potential use in automotive applications as well as separation processes whereby advancements could result in a reduction in carbon dioxide emissions and the production of natural gas in a more economically friendly manner. Along these pursuits, seven borazine-linked polymers (BLPs) have been synthesized through the introduction of p-phenylenediamine, 1,3,5-tris-(4-aminophenyl)benzene, benzidine, or tetra-(4-aminophenyl)methane with boron tribromide or boron trichloride followed by the thermolysis reaction of the resulting in …

The Effect Of Oxidation And Support On Tio2(110)-Supported Pdn (N=1-7) Clusters, S. Vincent Ong

Theses and Dissertations

First principles theoretical studies based on a gradient-corrected density functional approach have been carried out on the atomic and electronic properties and oxidation of Pdn (n=1-7) clusters supported on the TiO2(110) surface. The studies are aimed to address some of the fundamental issues related to the properties of supported Pdn clusters used as catalysts in oxidation reactions. Of those issues are the following: What are the atomic structures of Pdn clusters on the TiO2 surface? Upon oxidation, do O atoms from a dissociated O2 molecule spill over onto the underlying TiO2 sup- port? How strongly does spillover oxygen bind? What …

Total Synthesis Of 4'-Ester Resveratrol Analogs And 8.9-Amido Geldanamycin Analog And Toward The Total Synthesis Of (-)-Englerin A, Yong Wang

Theses and Dissertations

Total Synthesis of 4'-ester Resveratrol Analogs and 8, 9-amido Geldanamycin Analog and toward the Total Synthesis of (-)-Englerin A Yong Wang Department of Chemistry and Biochemistry, BYU Doctor of Philosophy The phytoalexin resveratrol and its 4'-ester analogs have been prepared with a decarbonylative Heck reaction. The deprotecting step has been modified and improved to increase yield and avoid chromatography. A set of resveratrol analogs and resveratrol have been tested with melanoma and pancreatic cell assays. The 8, 9-amido Geldanamycin analog has been synthesized with a convergent route, involving 28 simplified steps in its longest linear sequence. Synthetic methodologies, such as …

Design Of Control Release Drug Delivery System (Dds) For Imaging And Therapeutic Applications, Sweta Naik

Theses and Dissertations

The main challenge in disease treatment is no more the discovery of new therapeutic drugs, but to provide targeted delivery of therapeutic drugs to specific sites without incurring systemic toxicity effects. An efficient way of reducing the toxicity is by encapsulating the drug with a biodegradable matrix that can provide controlled release of the drug along with local heating of the drug. Local heating can be obtained by incorporating magnetic iron oxide particles that heat upon exposure to AC electromagnetic fields. The magnetic iron oxide nanoparticles are also gaining much attention as MRI contrast agents. Thus it would be of …

Wetting Transitions At Nanostructured Surfaces, Yazdi Jamileh Seyed

Theses and Dissertations

Shape of a droplet atop a surface heterogeneity at a nanoscale. Small aqueous droplets on homogeneous surfaces, surrounded by a reservoir of vapor are inherently unstable. In contact with supersaturated vapor, the drops will keep growing until they coalesce and form a contiguous aqueous phase. Alternatively, if vapor pressure is below that of the droplets, the droplets gradually evaporate. Departing from this common picture, when nanoscale droplets sit above hydrophilic patches on a heterogeneous surface, at certain conditions they can maintain a stable volume, determined by the pertinent contact angle and the size of the patches. Only the region under …

Follicular Dendritic Cells, Resting Cd4+ T Cells And Human Immunodeficiency Virus Expression, Changna Wang

Theses and Dissertations

Many events associated with Human Immunodeficiency Virus (HIV) infection/replication occur in and around the germinal centers (GCs) of secondary lymphoid tissues where follicular dendritic cells (FDCs) reside, suggesting that this microenvironment may contribute unique signaling that is important to viral progression. My research focused on characterizing signaling, both positive and negative, contributed by FDCs that affects HIV infection and replication. Specifically, I determined if FDC signals could induce the expression of latent HIV in T cells and if so, to characterize the signaling pathways involved. Moreover, I also examined the ability of FDCs to produce inhibitory signals that might block …

High Performance Liquid Chromatography - Mass Spectrometric Analysis Of Bile Acids And Coumarin Derived Sulfonamides, Udaya Bhasker Nasini

Theses and Dissertations

Bile acids are water- soluble steroids and biological emulsions useful in the digestion process of food. The conjugated bile acids play a major role in fat metabolism. Deconjugation of conjugated bile acids by bacterial enzymes produces free bile acids in the colon. The conversion of these primary bile acids takes place in the gut by bacterial flora. It is postulated that a difference in the molecular forms of various bile acids and their concentration profiles exists among various animals, depending upon their food habits and type of bacterial flora. Consequently, it may be possible to distinguish various types of carnivorous …

Synthesis And Characterization Of Tanninsulfonic Acid Doped Polyaniline (Tanipani) - Metal Oxide Nanocomposites For Solar Cell Applications, Venu Gopal Bairi

Theses and Dissertations

Nanocomposites of polyaniline have gained much importance due to their improved electronic properties. The presence of metal oxides in the nanocomposites may enhance the photovoltaic effect and increase the efficiency of solar cells. We have synthesized tanninsulfonic acid doped polyaniline (TANI-PANI) composites in view of preparing metal oxide complexed composites due to the presence of o-catechol in tannin. Tanninsulfonic acid doped polyaniline (TANIPANI)-TiO2 or Al2O3 nanocomposites were synthesized by varying the amount of TiO2 from 10% to 70% (with respect to the mass of aniline) and by carrying out the synthesis at -10° C. Covalent bonding of the metal oxide …

Synthesis Of Cyclen Based Receptors And Their Use In Separations Biotechnology., Vivek Kaushik

Theses and Dissertations

A number of purification techniques such as adsorption, centrifugation, chromatography, extraction, distillation, filtration, precipitation etc. to name a few, are commonly used for the purification. However, due to a constant need of purification of even more complex crude mixtures, be it reaction mixtures, various proteins and DNA from cell extracts or medicinal compounds and fragrances from plant extracts, scientists needed to consistently develop new and improved techniques of purification. One such great advancement in the field of chromatography was the development of affinity chromatography. It revolutionized the field of bioseparations technology, and the dream of single stage purification of complex …

Aryl Acetate Phase Transfer Catalysis: Method And Computation Studies, Meisha A. Binkley

Theses and Dissertations

Brief explanation and history of cinchona based Phase Transfer Catalysis (PTC). Studied aryl acetates in PTC, encompassing napthoyl, 6-methoxy napthoyl, phenyl and protected 4-hydroxy phenyl acetates. Investigated means of controlling the selectivity of the PTC reaction by changing the electrophile size, the ether side group size or by addition of inorganic salts. Found that either small or aromatic electophiles increased enantioselectivity more than aliphatic electrophiles, and that increasing the size of ether protecting group also increased selectivity. Positive effects of salt addition included either decreasing reaction time or increasing enantiomeric excess. Applied findings towards the synthesis of S-equol. Computational experiments …

The Formation And Stability Of Radical-Molecule And Radical-Radical Complexes And Their Importance In Atmospheric Processes, Jared M. Clark

Theses and Dissertations

This research explores the role that radical-molecule complexes play in the chemistry of Earth's atmosphere. The formation of such complexes can have direct and pronounced effects on the reaction and product outcome of atmospheric chemical reactions. Some attention is also given to the formation of radial-radical pre-reactive complexes in the HO + ClO system. Peroxy radicals (RO2) can form stable complexes with polar compounds such as H2O, NH3, and CH3OH. For the simplest RO2 radical, HO2, complex formation (e.g., HO2-H2O, HO2-NH3, and HO2-722;CH3OH) gives rise to a significant increase in the HO2 self-reaction rate constant. Although this phenomenon has been …

Ferritin Diversity: Mechanistic Studies, Disease Implications, And Materials Chemistry, Robert Joseph Hilton

Theses and Dissertations

The study of ferritin includes a rich history of discoveries and scientific progress. Initially, the composition of ferritin was determined. Soon, it was shown that ferritin is a spherical, hollow protein. Eventually, over several decades of research, the structure and some function of this interesting protein was elucidated. However, the ferritin field was not completely satisfied. Today, for example, researchers are interested in refining the details of ferritin function, in discovering the role of ferritin in a variety of diseases, and in using ferritin for materials chemistry applications. The work presented in this dissertation highlights the progress that we have …

Characterization Of The Desorption Electrospray Ionization Mechanism Using Microscopic Imaging Of The Sample Surface, Michael Craig Wood

Theses and Dissertations

Desorption electrospray ionization (DESI) is an ambient ionization technique for mass spectrometry. This solvent based desorption ion source has wide applicability in surface analysis with minimal sample preparation. Interest in improving detection limits, broadening applications, and increasing the spatial resolution for chemical imaging has led to studies of the DESI mechanism. An inverted microscope has been used to image interactions between the DESI spray and test analytes on a glass surface. Microscopic images recorded with millisecond time resolution have provided important insights into the processes governing analyte transport and desorption. These insights are the basis of a rivulet-based model for …

The Characterization Of Avian Polyomavirus, Satellite Tobacco Mosaic Virus, And Bacteriophage Cw02 By Means Of Cryogenic Electron Microscopy, Peter S. Shen

Theses and Dissertations

Viruses are the most abundant biological entity in the biosphere and are known to infect hosts from all domains of life. The aim of my work is to identify conserved and non-conserved features among the capsid structures of related and divergent icosahedral viruses via cryogenic electron microscopy, sequence analysis, molecular modeling, and other techniques. Bird polyomaviruses often cause severe disease in their hosts whereas mammalian polyomaviruses generally do not. Avian polyomavirus is a type of bird polyomavirus with an unusually broad host range compared to the restricted tropism of other polyomaviruses. Although most polyomaviruses have a conserved, rigid capsid protein …

The Molecular Mechanism Of Migraine, Kristin Dawn Watson

Theses and Dissertations

Migraine is a common, episodic neurological disorder that includes headache, nausea and hypersensitivity to sensory stimuli. During the headache phase of migraine, migraine patients can be especially hypersensitive to thermal stimuli. The unpredictable and episodic nature of migraine makes it difficult to treat and much of the mechanism of migraine has yet to be elucidated. A T44A substitution in casein kinase 1δ is inherited with migraine with aura. A transgenic mouse model suggests that animals with this mutation exhibit increased sensitivity to thermal stimuli after injection with nitroglycerin (NTG). We performed behavior assays that measure animal responses to thermal stimuli, …

Structures Of Poliovirus And Antibody Complexes Reveal Movements Of The Capsid Protein Vp1 During Cell Entry, Jun Lin

Theses and Dissertations

In the infection process, native poliovirus (160S) first converts to a cell-entry intermediate (135S) particle, which causes the externalization of capsid proteins VP4 and the N-terminus of VP1 (residues 1-53). The externalization of these entities is followed by release of the RNA genome, leaving an empty (80S) particle. Three antibodies were utilized to track the location of VP1 residues in different states of poliovirus by cryogenic electron microscopy (cryo-EM). "P1" antibody binds to N-terminal residues 24-40 of VP1. Three-dimensional reconstruction of 135S-P1 showed that P1 binds to a prominent capsid peak known as the "propeller tip". In contrast, our initial …

Novel Ion Trap Made Using Lithographically Patterned Plates, Ying Peng

Theses and Dissertations

A new approach of making ion trap mass analyzers was developed in which trapping fields are created in the space between two ceramic plates. Based on microfabrication technology, a series of independently-adjustable electrode rings is lithographically patterned on the facing surfaces of each ceramic plate. The trapping field can be modified or fine-tuned simply by changing the RF amplitude applied to each electrode ring. By adjusting the potential function applied to the plates, arbitrary trapping fields can be created using the same set of ceramic plates. Unlike conventional ion traps, the electrodes of planar ion traps have a non-equipotential surface, …

Investigating A Model Reversed-Phase Liquid Chromatography Stationary Phase With Vibrationally Resonant Sum Frequency Generation Spectroscopy, Arthur D. Quast

Theses and Dissertations

Reversed-phase liquid chromatography (RPLC) is a widely used technique for analytical separations but routinely requires empirical optimization. Gaining a better understanding of the molecular reasons for retention may mean more efficient separations with fewer trial and error runs to obtain optimized separations. Vibrationally resonant sum frequency generation (VR-SFG) is a surface specific technique that has allowed for in situ examination of model RPLC stationary phases under various solvent and pressure conditions. In order to improve on past work with model RPLC stationary phases two challenges had to be overcome. First, improved vibrational mode assignments of the C18 stationary phase were …

Progress Toward Theonellamide F, Jennifer Dawn Bettale

Theses and Dissertations

Theonellamide is a bicyclic peptide isolated from a marine sponge, which shows interesting biological activity. It contains several unnatural amino acids, among which are (2S,3R)-3-hydroxyasparagine (L-erythro-β-hydroxyasparagine) (β-OHAsn) and τ-L-histindino-D-alanine (τ-HAL). Although there were previous synthetic efforts toward each of these unnatural amino acids, the efforts were not ideal due to expensive starting material, time-consuming steps, and poor regioselectivity. The presented work demonstrates an inexpensive, enantioselective synthesis of β-OHAsn, which can be completed in a matter of weeks, as well as several attempts at a novel regiospecific approach toward τ-HAL, including work on a model study.

Growth Mechanisms Of Complex Organics In The Gas Phase And On Metal Nanoparticles Generated By A Laser Vaporization Process, Abdel Rahman Soliman

Theses and Dissertations

In this dissertation, the ion mobility mass spectrometry technique is used to study the possible mechanisms of formation of polyaromatic hydrocarbons (PAHs) and polyaromatic nitrogen-containing hydrocarbons (PANHs) via the ion-molecule reactions of acetylene neutrals with different aromatic cations, in order to infer the possible mechanisms of formation of PAHs and PANHs in different environments such as interstellar media under different ionizing conditions. Furthermore, this technique is used to probe structures, address the thermochemistry, and measure the kinetics of the product ions originated from these reactions. Reactions of benzene radical cations with acetylene produce styrene and naphthalene-type cations at high temperatures. …

Development Of Free-Label Sensing In Plastic Microfluidic Platforms Using Pulsed Streaming Potentials (Psp), Vera Fernando Luna

Theses and Dissertations

This work deals with the development of a new label-free detection technique called Pulsed Streaming Potential (PSP). Its novelty relies on the adaptation of a classical electrokinetic phenomenon (streaming potential) into a tool which can evaluate molecular interplay in label-free fashion. Implementation of PSP to microfluidic platforms allowed the label-free sensing of binding events to plastic (modified and unmodified) surfaces. It was demonstrated the use of real time PSP in plastic microfluidic platforms for determination of kinetic parameters of the interaction of proteins and plastic surfaces. Moreover, initial change of PSP after adsorption of proteins showed to be proportional to …