Browsing by Author "Elliott, Cecil Michael, committee member"

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Open Access
Chloro-, aryl-, and perfluoroalkylfullerenes
(Colorado State University. Libraries, 2009) Kuvychko, Igor V., author; Strauss, Steven H., advisor; Prieto, Amy L. (Amy Lucia), committee member; Hochheimer, Hans D., committee member; Rappé, Anthony K., 1952-, committee member; Elliott, Cecil Michael, committee member
The preparation, properties, stability, and handling of three classes of fullerene derivatives, chloro-, aryl-, and perfluoroalkylfullerenes, were studied in detail, in some cases for the first time. The same general methodology was used throughout this work: i) analytical methodology was developed and optimized using internal standards of known composition and purity; ii) the preparation of new compounds was studied by mapping the space of different reaction conditions using the newly developed analytical methods; iii) the efficient synthetic methods for the preparation of individual pure compounds were developed based on the mapping; iv) the pure compounds were characterized and their stability, or lack thereof, was studied. The first detailed study of fullerene chlorination led to isolation and characterization of several new chlorofullerenes: o-C60Cl2; p-C60Cl2; C60Cl4; C60Cl10; C70Cl6; and C70Cl8. It was discovered that chlorofullerenes are generally photosensitive in solution, both in the presence and absence of air and moisture. Effective methods for handling chlorofullerenes were developed (including a specialized crystallization technique). The experimental findings and theoretical calculations revealed the fundamental patterns governing multiple additions to fullerene cages. The efficient preparation of aryl- and perfluoroalkylfullerenes from chlorofullerene synthons was developed, leading to high yields of aryl- and mixed perfluoroethyl/hydrofullerenes (i.e., C60(C2F5)5H and C60(C2F5)3H). The first example of an organometallic complex of a perfluoroalkylfullerene was prepared using C60(C2F5)5H as a synthon. The direct addition of thermally-generated CF3 radicals to fullerenes was also studied. A specialized reactor was designed and built in order to validate mechanistic hypotheses. Good agreement between the experimental observations and predictions based on the hypotheses was observed. It led to the development of a new approach to efficient synthesis of C60(CF3)n with low values of n, including an unprecedented selective synthesis of C60(CF3)2 from unpurified fullerene extract.
Open Access
Fluorine-containing fullerenes and endometallofullerenes: synthesis, structure, and spectroscopic characterization
(Colorado State University. Libraries, 2010) Shustova, Natalia Borisovna, author; Strauss, Steven H., advisor; Anderson, Oren P., committee member; Szamel, Grzegorz, committee member; Elliott, Cecil Michael, committee member; Roess, Deborah A., committee member
Many new members of a relatively new class of exohedral fullerene derivatives with fluorine-containing electron-withdrawing groups have been prepared and studied by spectroscopic methods and X-ray crystallography. The fluorination and/or perfluoroalkylation reactions were performed with C60, C70, the higher hollow fullerenes C60+m (m = 14, 16, 18, 20, and 22), the endohedral metallofullerene Sc3N@C80-Ih(7), and the azafullerene dimer (C59N)2. Several efficient synthetic methods have been developed for perfluoroalkylation, which involved high-temperature reactions with AgCF3CO2 and with thermally or photochemically activated reactions with RFI reagents (RF = CF3, C2F5, n-C3F7, i-C3F7, n-C4F9, and n-C6F13). Structural studies of the C60(RF)n and C70(RF)n products demonstrated that variation of the size and structure of the RF radical led to the formation of derivatives with unprecedented addition patterns and hence unprecedented properties. Many of these derivatives were shown to have superior electron-accepting properties. Trifluoromethylation of a sample of insoluble hollow higher fullerenes resulted in the structural characterization of several new dodecakis(trifluoromethyl) fullerene compounds, and this led to the first experimental observation of fullerenes C74-D3h and C78-D3h(5). In the case of trifluoromethylation of (C59N)2, a strong effect of the heteroatom on the addition patterns of the products was discovered. The first X-ray crystal structure of a single regioisomer of C59N(CF3)5, as well as spectroscopic studies of C59N(CF3)7,9,11, revealed unexpected addition patterns which resemble that of Cs-C60X6 derivatives. The isolation and characterization of seventeen Sc3N@(C80-Ih)(CF3)n (even n = 2-16) compounds, including the X-ray structures of Sc3N@(C80-Ih(7))(CF3)10, Sc3N@(C80-Ih(7))(CF3)12, Sc3N@(C80-Ih(7))(CF3)14, and Sc3N@(C80-Ih(7))(CF3)16, have demonstrated for the first time a strong mutual effect of (i) the presence of the Sc3N cluster on the addition pattern and (ii) the addition pattern on the position of and structure of the Sc3N cluster.
Open Access
Part I: Electroreductive polymerization of nanoscale solid polymer electrolytes for three-dimensional lithium-ion batteries. Part II: Physical characterization and hydrogen sorption kinetics of solution-synthesized magnesium nanoparticles
(Colorado State University. Libraries, 2010) Arthur, Timothy Sean, author; Prieto, Amy L. (Amy Lucia), advisor; Bailey, Travis Slade, committee member; Elliott, Cecil Michael, committee member; Shores, Matthew P., committee member; Williams, John D., committee member
To view the abstract, please see the full text of the document.
Open Access
Single potential electrodeposition of nanostructured battery materials for lithium-ion batteries
(Colorado State University. Libraries, 2010) Mosby, James Matthew, author; Prieto, Amy L. (Amy Lucia), advisor; Elliott, Cecil Michael, committee member; Ladanyi, Branka M., committee member; Manivannan, Venkatesan, committee member; Shores, Matthew P., committee member
To view the abstract, please see the full text of the document.
Open Access
Synthesis, properties and applications of single-component anion-exchange materials
(Colorado State University. Libraries, 2009) Caamaño, Samira, author; Strauss, Steven H., advisor; Meersmann, Thomas, committee member; Rickey Dawn, committee member; Elliott, Cecil Michael, committee member
Several tetraalkylated ferrocenium salts and neutral modified ferrocenes, both new and previously synthesized, were studied in detail. Some of these salts have been used in the past as anion-exchange extractants for attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Different crystallographic, electrochemical and spectroscopic parameters were analyzed to study properties like cation size and its effect in selectivity, morphology of thin films made from these salts, both in the surface and in the bulk of the film, and film changes with time. It was found that when relative cation sizes are compared for different cations in these salts, the size increases in one dimension, which affects ion-exchange selectivity depending on what the non-aqueous phase containing the extractant is (either a water-immiscible solvent, a three-dimensional thin film or a monolayer self-assembled on an electrode surface). The effect of C–H...O hydrogen bonding in the cation–anion interactions was investigated. A model was proposed for the structure of thin films of a particular type of the ferrocenium salts, which was based on atom distances from the crystallographic data. Atomic force microscopy was used to study the morphology of surfaces of thin films, which had never been done before; the results were consistent with the hypothesis that there is a clear difference in the way that organic solutions of ferrocenium+NO3- and ferrocenium+ClO4− arrange molecularly as solvent evaporates, forming very different thin films. The use of an ATR-FTIR technique previously developed for the detection and quantification of anionic pollutants was investigated and optimized for new sample volumes, film thicknesses and analytes. Multiple-anion detection in aqueous media was examined. Among the new analytes studied was dodecylsulfate, (DDS−), the anion in the detergent sodium dodecylsulfate (SDS). These studies constituted a novel application of the ATR-FTIR spectroscopy technique in heart-valve research, which uses the detergent to decellularize tissue samples with the objective of preparing biological scaffolds free of cytotoxicity. A new ferrocene salt containing a nitrogen atom, which bears the positive charge of the cation, was successfully synthesized. This compound displayed better stability in biological solutions than other ferrocenium salts used previously. The use of this compound aided in answering the question of whether SDS leaches out of SDS-treated tissues after a soaking regime has been implemented: SDS does leach from treated tissues in potentially cytotoxic concentrations which are dependent on the initial treatment. It was also discovered that SDS leaches both as a free anion and, in initial stages of the soaking regime, complexed to other species. A new method was developed to detect and quantify anions in aqueous samples. This method also mitigated instability issues present in the use of certain ferrocenium salts and opened doors for conventional FTIR quantification of species using this kind of extractant. The synthesis of [35S]SDS was evaluated by successfully synthesizing SDS in the Strauss Research Group laboratories, using standard starting materials, one of which (H2SO4) can be obtained in its radioactively labeled form. A long term objective of this synthesis was to eventually quantify [35S]SDS directly in [35S]SDS-treated tissue samples, after a soaking regime, using beta scintillation counting.