Chemistry Commons^™

Muon-Fluorine Entangled States In Molecular Magnets, T Lancaster, S J. Blundell, P J. Baker, M L. Brooks, W Hayes, F L. Pratt, Jamie L. Manson, M M. Conner, J A. Schlueter

Chemistry and Biochemistry Faculty Publications

The information accessible from a muon-spin relaxation experiment can be limited due to a lack of knowledge of the precise muon stopping site. We demonstrate here the possibility of localizing a spin polarized muon in a known stopping state in a molecular material containing fluorine. The muon-spin precession that results from the entangled nature of the muon spin and surrounding nuclear spins is sensitive to the nature of the stopping site. We use this property to identify three classes of sites that occur in molecular magnets and describe the extent to which the muon distorts its surroundings.

Chemical Constituents And Biological Activity Of Three Tanzanian Wild Mushroom Species, L.D. Baraza, C. C. Joseph, M. J. Moshi, M. H. H. Nkunya

Tanzania Journal of Science

The three Tanzanian wild mushroom species Termitomyces letestui, Lactarius edulis and Agaricus sp. aff. arvensis yielded ergosterol, 5,8-peroxyergosterol and ergosta-5,22-dien-3β-ol, and a mixture of ergosterol, ergosta-7,22-dien-3β-ol and ergosta-7-en-3β-ol whose composition was deduced from gas chromatography/mass spectroscopic (GC/MS) analysis of the trimethysilylated mixture. GC/MS analysis of the lipid fraction from T. letestu revealed the presence of linoleic (C18:2), stearic (C18:0), oleic (C18:1), palmitic (C16:0), pentadecanoic (C15:0) and myristic (C14:0) acid. Polar T. letestui and L. edulis fractions yielded α,α,1'trehalose andmannitol. Some of the crude extracts from the three mushroom species showed mild antimicrobial, mosquito larvicidal and cytotoxic activities. The chemical composition …

Exploiting Self-Assembly For Ligand-Scaffold Optimization: Substrate-Tailored Ligands For Efficient Catalytic Asymmetric Hydroboration, Shin A. Moteki, James M. Takacs

James M. Takacs Publications

A self-assembled ligand library (SAL XY) affords a wide range of R/S ratios in Rh-catalyzed asymmetric hydroboration (nbd = 2,5norbornadiene, R* is a chiral substituent). Ligand-scaffold optimization reveals “substrate-tailored” ligands that afford high regio- and enantioselectivity for a variety of ortho-substituted styrene derivatives.

Includes article (4 pp.) and supporting information (106 pp.).

Preparation Of Divalent And Trivalent Antigens For Immunogical Studies On Degranulation Of Mast Cells And Preparation Of Ceragenins For Antiviral Studies Against Vaccinia Virus., Dianliang Geng

Theses and Dissertations

CHAPTER 1

Aggregation of receptors for IgE (Fc RI) causes mast cells and basophils to release preformed contents of granules, including histamine and a variety of enzymes. This process, called degranulation plays a central role in allergic reactions. Methods to study this process are to create multivalent ligands which can interact with the receptors and, in turn, lead to aggregation of the receptors. We prepared a series of fluorophore-labeled divalent and trivalent antigens to study the degranulation of mast cells. Trivalent antigens proved to be much better stimulators for degranulation of mast cells than divalent antigens. These results indicate that …

Pyridinium Bisretinoids: Synthesis And Photoactivated Cytotoxicity, Junping Gao

Theses and Dissertations

This thesis discusses pyridinium bisretinoid compounds (PBRs), which were prepared for two purposes: 1) to use them as standards for detection of novel fluorophores in human RPE cells, which may be involved in age-related macular degeneration (AMD), and 2) to use them in the development of a targeted and triggered drug delivery system for cancer therapy. We prepared a selection of PBRs using a one-pot biomimetic method; synthesis, mechanisms for formation, and characterization of these compounds is described. We also explored the photoreactivity of three novel PBR compounds and found that these PBRs form oxidation products under blue-light irradiation. The …

Total Synthesis Of (+/-)-Goniomitine Via A Formal Nitrile/Donor-Acceptor Cyclopropane [3 + 2] Cyclization., Christian L Morales, Brian L Pagenkopf

Chemistry Publications

The total synthesis of (+/-)-goniomitine has been accomplished in 17 linear steps with 5.2% overall yield starting from commercially available delta-valerolactam. A synthetic highlight includes the first application of a formal [3 + 2] cycloaddition between a highly functionalized nitrile and a donor-acceptor cyclopropane to prepare an indole nucleus. The use of a microwave reactor is shown to greatly improve the reaction times for two steps.

Study Of The Reproducibility Of Proteomics Methods And Variability Of Fruit Fly Proteomes., Thomas Franklin Culwell

Theses and Dissertations

The reliability of biomarker discovery by means of proteomics has been called into question. It was speculated that "background noise" variation resulting from differences in preparation and handling of samples and proteome dynamics may mask subtle, yet important, differences due to the biological condition. Little is understood about complex proteomes and their variability. A critical aspect of proteomic biomarker research that is largely unexplored is the comparative reproducibility of certain methods such as two-dimensional gel electrophoresis and liquid chromatography/mass spectrometry. In particular, with liquid chromatography/mass spectrometry, it is not known whether variability in peptide quantitation is dependent on any of …

Pyridinium Bis-Retinoids A2-Dopamine And A2-Cadaverine: Implications In Age-Related Macular Degeneration And Cancer, Mckenzie Ruth Pew

Theses and Dissertations

Age-related macular degeneration (AMD) is the leading cause of blindness in the United States of America. The pyridinium bis-retinoid A2-ethanolamine (A2E) has been implicated to play a role in AMD. We have observed novel pyridinium bis-retinoids through melanolipofuscin and human RPE extractions that may also play a role in the pathology of AMD. We have begun the construction of an amino-retinoid library in order to identify these ocular compounds. The compounds from the amino-retinoid library are also used in a targeted and triggered drug delivery system for treating cancer. Folic acid is coupled with the amino-retinoids to specifically target cancer …

Development Of Fullerene Based Sturctures For Photovoltaic And Electronic Applications, Amit Palkar

All Dissertations

Solar energy can be envisioned as a long term alternative to rapidly depleting fossil fuels. The energy from the sun can be harnessed by constructing donor-acceptor (D-A) type devices where the incident photon induces the transfer of an electron from the donor to the acceptor. If recombination is prevented, this electron can then be channeled through an external circuit, thus leading to the generation of photocurrent. Porphyrins, which are the naturally occurring pigments in photosynthesis, have been widely established as donors while fullerenes, such as C₆₀ and C₇₀ , due to their unique electron accepting properties, have been …

Lithium-Conducting Ionic Melt Electrolytes From Oligomeric Ethylene Glycols: Synthesis And Characterization, Boutros Hallac

All Dissertations

Commercial lithium ion cells consist of electrolytes that undergo salt concentration polarization which is acute upon high discharge currents. This type of polarization occurs as a result of the mobility of more than one ionic species in the presence of an electric field. One way to overcome it is by employing a material that would allow the mobility of one ionic species. This thesis will describe the synthesis and characterization of several fluorosulfonimide and fluorosulfonate based ionic liquids/melts as electrolytes having lithium as the only mobile ion. These materials were prepared by the nucleophilic addition reaction of a deprotonated polyether …

Thermodynaimic Study Of Nucleic Acids Recognition By Aminoglycosides , Hongjuan Xi

All Dissertations

ABSTRACT


Since the origin of first aminoglycosides antibiotics, streptomycin, isolated by Selman Waksman about 60 years ago, a number of aminoglycosides antibiotics were discovered to treat different infections. Neomycin class aminoglycosides were found to originally target the A site 16S rRNA in the 30S subunit of the ribosome within the Gram-negative bacteria. In addition to its antibacterial effect, aminoglycosides were also found to binding to various other viral RNA structures such as TAR and RRE of HIV, Group I introns and hammerhead ribozyme, implying its potential to be used as antiviral reagent.

Furthermore, previous studies in our laboratory discovered a …

Studies Of The Stability And Potential Applications Of Pyrrolidinofullerenes And Other Fullerene Derivatives, Olena Lukoyanova

All Dissertations

Over the last decade, the variety of chemically modified fullerenes and their potential applications has increased significantly. Among fullerene derivatives, pyrrolidinofullerenes are one of the most widely synthesized types since they can be easily and efficiently obtained via simple reactions from both empty and endohedral fullerenes. Although fullerenes in general and pyrrolidinofullerenes in particular have been considered for numerous applications in electronic and optoelectronic devices, photovoltaics, medicinal chemistry, etc., their potential application in the evolving field of molecular electronics has not been extensively explored. The envisioned role of the fullerenes usually involves storage or transport of electrons. Therefore, studies of …

Effects Of Water Vapor On The Kinetics Of The Methylperoxy Radical Self-Reaction And Reaction With Hydroperoxy, Alecia Mower

Theses and Dissertations

The gas phase reactions of CH3O2 + CH3O2, HO2 + HO2, and CH3O2 + HO2 in the presence of water vapor have been studied at temperatures between 263 and 303 K using laser flash photolysis coupled with UV time-resolved absorption detection at 220 nm and 260 nm. Water vapor concentration was quantified using tunable diode laser spectroscopy operating in the mid-IR. The HO2 self-reaction rate constant is significantly enhanced by water vapor, consistent with what others have reported, whereas CH3O2 self-reaction and the cross-reaction (CH3O2 + HO2) rate constants are nearly unaffected. The enhancement in the HO2 self-reaction rate coefficient …

Prevention Of Staphylococcus Epidermidis Biofilm Formation Using A Low-Temperature Processed Silver-Doped Phenyltriethoxysilane Sol–Gel Coating, Niall Stobie, Brendan Duffy, Declan Mccormack, John Colreavy, Martha Hidalgo, Patrick Mchale, Steven Hinder

Articles

Sol–gel coatings which elute bioactive silver ions are presented as a potential solution to the problem of biofilm formation on indwelling surfaces. There is evidence that high-temperature processing of such materials can lead to diffusion of silver away from the coating surface, reducing the amount of available silver. In this study, we report the biofilm inhibition of a Staphylococcus epidermidis biofilm using a low-temperature processed silver-doped phenyltriethoxysilane sol–gel coating. The incorporation of a silver salt into a sol–gel matrix resulted in an initial high release of silver in de-ionised water and physiological buffered saline (PBS), followed by a lower sustained …

Fabrication Of Pillar-Structured Thermal Neutron Detectors, Rebecca J. Nikolić, Adam M. Conway, Catherine E. Reinhardt, Robert T. Graff, Tzu Fang Wang, Nirmalendu Deo, Chin Li Cheung

Barry Chin Li Cheung Publications

Pillar detector is an innovative solid state device structure that leverages advanced semiconductor fabrication technology to produce a device for thermal neutron detection. State-of-the-art thermal neutron detectors have shortcomings in achieving simultaneously high efficiency, low operating voltage while maintaining adequate fieldability performance. By using a 3-dimensional silicon PIN diode pillar array filled with isotopic boron 10, (¹⁰B) a high efficiency device is theoretically possible. The fabricated pillar structures reported in this work are composed of 2 μm diameter silicon pillars with a 4 μm pitch and pillar heights of 6 and 12 μm. The pillar detector with a …

A Modified Route To Cyclopenta[C]Thophenes Via Grignard Reagents, Amber Bell

Masters Theses & Specialist Projects

The synthesis of cyclopenta[c]thiophenes is sparsely found in literature due to the several difficulties of their synthesis. Our research has shown that we could modify a previously known route to 1,3-disubstituted cyclopenta[c]thiophenes using traditional Grignard chemistry. Along the way we discovered the synthetic route we were using had several omissions. Therefore, we were required to completely fill in missing experimentals in order to obtain each cyclopenta[c]thiophene intermediate, in high purity and good yield. In addition, we were able to fully characterize via NMR, our intermediates which was found in the literature. Finally, we were able to show using 'H 13 …

Excited-State Equilibration Over 30 Å In A Platinum(Ii) Quinolinolate−Bridge−Platinum(Ii) Porphyrin Complex, Victor A. Montes, Michael A. J. Rodgers, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

Long-range triplet excited-state equilibration occurs over a nanometric distance between platinum(II) 8-quinolinolate ((3)Ptq(2) = 1.87 eV) and platinum(II) tetraphenylporphyrin ((PtTPP)-Pt-3 = 1.89 eV). The equilibrium is mediated by a fluorene-thiophene-fluorene bridge ((FTF)-F-3 = 1.92 eV) and is characterized by a double-exponential decay (tau(1) = 39 +/- 4 ps; tau(2) = 351 +/- 15 ps) that suggests the participation of three separate excited states : (3)Ptq(2), (FTF)-F-3, and 3PtTPP, respectively. Numerical simulation of the dual equilibrium allowed for estimation of the individual rate constants for each of the reversible steps (k(ET) = 3.9 x 10(9)-4.1 x 10(10) s(-1)). As a result …

Tris(Dialkylamino)Aluminums: Syntheses, Characterization, Volatility Comparison, And Atomic Layer Deposition Of Alumina Thin Films, Casey R. Wade, Carter Silvernail, Chiranjib Banerjee, Axel Soulet, James Mcandrew, John A. Belot Jr.

Department of Chemistry: Faculty Publications

The syntheses and characterization of both tris(diethylamino)aluminum and tris(diisopropylamino)aluminum are presented in this letter. Characterization includes vapor pressure measurements and comparison of the two non-pyrophoric precursors showing them to be viable alternatives to trimethylaluminum. Ultimately, tris(diisopropyl)aluminum was successful in the atomic layer deposition of alumina thin films.

Markov Processes In Single Molecule Fluorescence, David Talaga

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

This article examines the current status of Markov processes in single molecule fluorescence. For molecular dynamics to be described by a Markov process, the Markov process must include all states involved in the dynamics and the first-passage time (FPT) distributions out of those states must be describable by a simple exponential law. The observation of non-exponential FPT distributions or other evidence of non-Markovian dynamics is common in single molecule studies and offers an opportunity to expand the Markov model to include new dynamics or states that improve understanding of the system.

Formation Of Peptide Nanospheres And Nanofibrils By Metal Coordination, Mikhail V. Tsurkan, Michael Y. Ogawa

Chemistry Faculty Publications

Two amphipathic polypeptides were coordinated to the cis positions of a square planar Pt(II) complex in order to provide the metal center with two noncovalent oligomerization domains. This resulted in the formation of new metal-peptide nanoassemblies which are shown to exist as nanometer-sized spheres and fibrils. Construction of these assemblies was based on the 30-residue polypeptide AQ-Pal14 which was designed for its ability to self-assemble into the common protein oligomerization motif of a noncovalent coiled-coil, and modified to contain a metal-binding 4-pyridylalanine residue at its surface. When AQ-Pal14 was reacted with Pt(en)(NO3)(2), a new metal-peptide complex was formed in which …

Shake & Bake: Dual-Use Chemicals, Contexts, And The Illegality Of American White Phosphorus Attacks In Iraq, Joseph D. Tessier

The University of New Hampshire Law Review

[Excerpt] “On November 29, 2005, in a Department of Defense press conference with Secretary of Defense Donald Rumsfeld and Gen. Peter Pace, Chairman of the Joint Chiefs of Staff, General Pace stated that white phosphorus “is a legitimate tool of the military,” and can be used for illumination, smoke, and incendiary purposes. Incredibly, the Department of Defense released an addendum to the press conference clarifying that white phosphorus was not used as an incendiary weapon. According to General Pace, “it was well within the law of war to use white phosphorus . . . for marking and screening.” This was …

Synthesis, Study Of Self-Assembly, And Trivalent Lanthanide Metal Ion Recognition Characteristics Of Amphiphilic Acylpyrazolones And Amphiphilic Acylisoxazolones, Venkat Reddy Guduru

Dissertations

This research project focused on the separation of trivalent lanthanide metal ions by HPLC using amphiphilic acylpyrazolones and amphiphilic acylisoxazolones. The central hypothesis of our research project is that the nanoscale self-assembly nature of amphiphilic ligands (chelating lingads) can influence their metal ion recognition and separation. To test the central hypothesis, we have synthesized a family of novel amphiphilic ligands and employed them as model systems for the separation of trivalent lanthanide metal ions. Several novel intermediates such as 4-acylated. N -acylated, O -acylated pyrazolones and isoxazolones, have been efficiently synthesized and fully characterized.*

The trivalent lanthanide metal ion recognition …

Molecules That Target Beta-Amyloid, Cliff I. Stains, Kalyani Mondal, Indraneel Ghosh

Cliff Stains Publications

The devastating effects of Alzheimer’s and related amyloidogenic diseases have inspired the synthesis and evaluation of numerous ligands to understand the molecular mechanism of the aggregation of the beta-amyloid peptide. Our review focuses on the current knowledge in this field with respect to molecules that have been demonstrated to interact with either oligomeric or fibrillar forms of the beta-amyloid peptide. We describe natural proteins, peptides, peptidomimetics, and small molecules that have been found to interfere with beta-amyloid aggregation. We also detail recent efforts in selecting molecules that target beta-amyloid isolated from antibody, protein, and peptide libraries. These new molecules will …

Ral Interacting Protein (Ralbp1): Linking Glutathione Conjugate Transport To Oxidative Stress Defenses And Signaling Pathways, Dilki Wickramarachchi

Chemistry & Biochemistry Dissertations - Archive

The glutathione-conjugate transporter protein DNP-SG ATPase was demonstrated to be identical to the independently cloned Ral-effector, Ralbp1. Glutathione-conjugate transport is linked to substrate-stimulated ATPase activity, while GTPase stimulating activity (GAP-activity), and clathrin-coated pit-binding activity was demonstrated for this protein by different groups of investigators. The relationship between these activities and physiological functions of Ralbp1 were not clear. The present studies were designed to address the hypothesis that the ability of Ralbp1 to couple the hydrolysis of ATP with the movement of substances, i.e. its transport activity, is the crucial element that allows Ralbp1 to function as a stress-defense protein. Results …

Studies Towards Bioactive Imidazoles, Karuna Koda

Chemistry & Biochemistry Theses - Archive

The work presented in this thesis focuses on the development of an enantioselective and practical route form the total synthesis of villagorgin via haplosleridamine imidazole alkaloid containing β- carboline moiety by employing the well-known Pictet-Spengler and Fischer indole reactions. We approached two different ways inorder to synthesize these molecules Our first approach focused on using a Dieckmann condensation, requiring the preparation of the corresponding diester. Initial attempts to prepare this substrate directly from histidine were unsuccessful, however after conversion to the N-benzzylamine and reductive amination with ester provided the key diester compound. Unfortunately, attempts to effect the Dieckmann reaction were …

Supramolecular Chemistry On Carbon Dioxide, Hexiang Zhang

Chemistry & Biochemistry Theses - Archive

This dissertation describes approaches towards designs, syntheses, characterizations, and applications of supramolecular chemistry on carbon dioxide. Chapter 1 briefly overviews the field of supramolecular chemistry and highlights its horizons, also introduces the progress of sensing devices on chemical warfare agents. Chapter 2 introduces a modular approach to detect chemical warfare agent: phosgene by Fluorescence Resonance Energy Transfer (FRET). It combines the chemical reactivity between amines and phosgene with fluorescence properties of coumarin fluorophores, forms a fast, selective and reliable sensing system. Chapter 3 overviews the chemistry between amines and carbon dioxide and introduces the applications of this reaction in molecular …

Ring Closing Enyne Metathesis Of Imidazole Derivatives And Subsequent Diels-Alder Reaction, E. Vindana Ekanayake

Chemistry & Biochemistry Theses - Archive

The work presented in this thesis describes the development of new synthetic routes to elaborate simple imidazole derivatives into complex imidazole molecules by the application of different sequential transformations. The first transformation considered is the ring closing enyne metathesis (RCEYM) of imidazoles. To carry out this reaction various allyl and propargyl derivatives of imidazole have been synthesized. These enyne substrates have been varied by changing the positions on the imidazole, as well as changing the protecting groups. All substrates contain trimethysilyl-protected propargyl derivative as the "yne" moiety. After the successful preparation of different enyne substrates, they were subjected to the …

Multiply Charged Cationic Pairing Agents For Trace Analysis Of Anionic Species By Electrospray Ionization Mass Spectrometry, Jeffrey William Remsburg

Chemistry & Biochemistry Theses - Archive

Electrospray ionization is one of the most broadly useful and successful approaches for coupling high performance liquid chromatography to mass spectrometry. Most of the research in electrospray ionization mass spectrometry (ESI-MS) has been limited to the positive ion mode, where lower detection limits are generally achieved, due several advantages over the more problematic negative ion mode. However, if one wishes to study anionic species, the negative ion mode traditionally had to be employed, and the problems associated with the negative ion mode had to be tolerated or ameliorated as much as possible Recently, novel work has been done to take …

Weak Ferromagnetism In Fe₁₋ₓcoₓsb₂, Rongwei Hu, Raphäel P. Hermann, Fernande Grandjean, Yong Jae Lee, John B. Warren, Vesna F. Mitrovic, Cedomir Petrovic

Chemistry Faculty Research & Creative Works

Weak ferromagnetism in Fe_1-xCo_xSb₂ is studied by magnetization and Mössbauer measurements. A small spontaneous magnetic moment of the order of ~ 10^-3µ_B appears along the b axis for 0.2 ≤ x ≤ 0.4. Based on a structural analysis, we argue against extrinsic sources of weak ferromagnetism. We discuss our results in the framework of the nearly magnetic electronic structure of the parent compound FeSb₂.

Synthesis And Characterization Of Ruthenium Bipyridyl Complexes For Detecting Nerve Gas Agents And Explosives, Arambe Gedara Aruna Weerasinghe

Masters Theses

Five novel 2,2 '-bis bi pyridine Ru(II) complexes have been synthesized and characterized using ¹H NMR, ¹³C NMR, ¹H-¹H-COSY, elemental analysis, fast atom bombardment or electrospray mass spectra and electronic absorption spectroscopy. Binding of Ru (11) complexes with nerve gas analogos such as diethyl chlorophosphate (DCP), dimethyl methyl phosphonate (DMMP) and hydrolyzed product (HCl) has been investigated by electronic absorption, fluorescence, and lifetime studies. Compound 1 showed a quenching in ³MLCT emission after an initial increase in intensity upon the addition of DCP with a bathochromic shift of 25 nm. Compound 2 exhibit a …