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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Guest-Host Chemistry Of P-Sulfonatocalix[6]Arene And Nizatidine, Galia Debelouchina
Guest-Host Chemistry Of P-Sulfonatocalix[6]Arene And Nizatidine, Galia Debelouchina
Honors Theses
This work investigates the guest-host chemistry in water of p-sulfonatocalix[6]arene and a number of guests related to the amino acids arginine and lysine. Two questions are particularly important: what are the interactions that drive guest-host binding and what is the role of the solvent. The answers to these questions are investigated with isothermal titration calorimetry (lTC), which gives K, ?H, and ?S, and pressure perturbation calorimetry (PPC), which allows the calculation of the thermal coefficient of expansion ? and relating it to a molecule's structure-breaking or structure-making properties. The ITC data suggests that hydrogen bonding and charge-charge interactions are the …
The Synthesis Of Biomimetic Tungsten And Molybdenum Complexes, John Sterling Cole Iii
The Synthesis Of Biomimetic Tungsten And Molybdenum Complexes, John Sterling Cole Iii
Honors Theses
The synthesis of novel biomimetic molybdenum and tungsten compounds that are potential model complexes for molybdenum and tungsten oxidase enzymes is being pursued. Model complexes such as these provide a better understanding of the basic chemistry of a metal center in an environment similar to that found in particular enzyme active sites. This understanding provides a good starting point for biologists or biochemists studying those biological systems. The first target complex will incorporate a tetradentate-S4 ligand (L) that features two biphenyl-S2 fragments joined by a propyl linker. The second target complex will incorporate a bidentate ligand (L') with a singly …
An Analysis Of The Effect Of Carbon Dioxide On The Decay Rates Of Superoxide, Michael Jay Walsh
An Analysis Of The Effect Of Carbon Dioxide On The Decay Rates Of Superoxide, Michael Jay Walsh
Honors Theses
The radical dioxygen anion, superoxide has been shown to react with carbon dioxide in nonprotic and aqueous systems. Indirect evidence suggests that superoxide also reacts with carbon dioxide and carbonate species dissolved in water. This study involved conducting experiments to determine the decay rate of superoxide in the presence of carbon dioxide and carbonate species. Experiments were conducted by sparging an alkaline bicarbonate buffer with carbon dioxide and measuring the decay rate of superoxide added to the solution. Although the specific reaction mechanism and rates have not been determined first order superoxide decay rates as high as 3.8x10-2s-1 were obtained …
Investigation Of Iron (Iii) Desferrioxamine B Oxalate Ligand Exchange By Uv-Vis Spectroscopy: The Next Step In Developing A Quantitative Analytical Method For Measuring Bioavailable Iron In Marine Ecosystems, Ken L. Pitter
Honors Theses
To date there are no analytical techniques designed to exclusively measure bioavailable iron in marine environments. The goal of this research is to develop such a technique by isolating the bioavailable iron using the terrestrial siderophore desferrioxamine B (DFB). This project contained many challenging aspects, but the specific goal of this study was to develop a robust analytical technique for quantification of Fe(III)-DFB complexes at nanomolar concentrations. Past work showed that oxalate (Ox) promotes photodissociation of Fe(III)-DFB to Fe(Il), and we are specifically interested in the mechanism of this process. A model was developed using known thermodynamic constants for Fe(III)-DFB …
Photochemical Generation Of 2-Methoxy-2methylpropylidene And Its Rearrangement Pathways, Stanislav Presolski
Photochemical Generation Of 2-Methoxy-2methylpropylidene And Its Rearrangement Pathways, Stanislav Presolski
Honors Theses
2-methoxy-2-methylpropylidene was photochemically generated from a non-nitrogenous precursor, 1a,9b-Dihydro-IH-cyclopropa[1]phenanthrene-l-etbane 2-methoxy-2-methyl, available in two steps from phenanthrene. Two competing rearrangement pathways were observed for the p-methoxy carbene, 1,2-methyl shift and C-H insertion, which had varying weights depending on the solvent used. Nevertheless, the C-H insertion was always predominant, contrary to the current understanding of B-substituted carbenes, which apparently needs revision. An attempt was also made to measure by LFP the rate constant of rearrangement and lifetime of the stabilized l-chloro-2-methoxy-2-metbylpropylidene.
The Synthesis And Characterization Of Bicyclooxacalixarenes, Kevin J. Selby
The Synthesis And Characterization Of Bicyclooxacalixarenes, Kevin J. Selby
Honors Theses
Bicyclooxacalixarenes were synthesized in high yield via a selective, room temperature Sn Ar reaction of phluoroglucinol with 2,6-dichloropyridines. Functionality on the 2,6-dichloropyridioe was varied by changing the electron-withdrawing groups in the 3 and 5 positions (using chlorine, nitro groups, and cyano groups) and the side-chains in the 4-position (using ethyl, butyl, phenyl and ρ-tolyl groups). The resulting cage-like molecules were studied by X-ray crystallography and tested for metal complexation.
Analytical Tools For Studying Phosphorus And Nitrogen Lake Nutrient Dynamics And Their Application To The Field, Ivan Mihajlov
Analytical Tools For Studying Phosphorus And Nitrogen Lake Nutrient Dynamics And Their Application To The Field, Ivan Mihajlov
Honors Theses
In order to evaluate the causes and conditions that lead to cyanobacteria blooms in northern temperate lakes, studies of nutrients such as total phosphorus, total nitrogen, phosphate, and nitrate are necessary. Sensitive, environmentally friendly and cost-effective techniques were developed to detect ppb-level nitrates and phosphates in the lake water. Phosphate was analyzed by luminol chemiluminescence, while the quantification of nitrate was performed by capillary electrophoresis (CE) using indirect UV detection, with a background electrolyte consisting of pyromellitic acid, hexamethonium hydroxide and triethanolamine. Sample injection methods for the CE were optimized for the analysis in Belgrade Lakes, Maine. Vertical profiles of …