231st ACS National Meeting

Atlanta, Geogia
March 26-30, 2006
Barron Research Group -  Posters and Talks

Transition metal catalyzed epoxidation and cage-opening of fullerenes

Robin E. Anderson, Department of Chemistry, Rice University, Houston, TX 77005, and Andrew R. Barron, Department of Chemistry, Center for Nanoscale Science and Technology, Rice University

The fullerene epoxide, C60O, is the simplest fullerene derivative and plays an important role in the synthesis of various organic, organometallic, and polymeric fullerene derivatives. Past methods of fullerene epoxidation include ozonation, ultrasonication and electrochemical oxidation, however none of these have successfully produced more than six single oxygens on the fullerene cage. Molybdenum (VI) oxide bis(2,4-pentanedionate), is known to catalytically epoxidize olefins in the presence of hydroperoxides. Through this research we have shown that this olefin chemistry can be applied to fullerenes. We have successfully synthesized a fullerene with 13 epoxide groups. This highly epoxidized species will allow for easier and greater functionalization of fullerenes. In addition to epoxidizing the fullerene, it was discovered that the reaction also produced open-cage fullerenes. These new species could be employed in the production of endohedral fullerenes.

The inhibition reaction mechanism of the heterocyclic diazoles on metallic surfaces investigated via Vertical Scanning Interferometry (VSI) and X-Ray Photoelectron Spectroscopy

Author: Corina Lupu, Ksenija Babic-Samardzija, Andrew Barron and Norman Hackerman, Department of Chemistry, Rice University, and Andreas Lüttge, Geochemistry Department, Rice University, Houston, TX 77005-1892

The investigation of the reaction pathways by which organic inhibitors act upon specific surfaces it is important in elucidating or preventing different chemical processes, e.g. corrosion, hydration, oxidation, etc. Our goal is to show how by synergistic studies of surface composition and speciation using XPS coupled with a detailed topographical and surface roughing measurements performed via Vertical Scanning Interferometry (VSI) new insights into deep understanding of the chemical reaction mechanism are obtained. In addition, polarization resistance values, Tafel curve effects, and electrochemical impedance spectroscopy were used to obtain a complementary information on the processes occurred at the solution-metal interface. We will focus on the observation of the inhibitor mechanism of the heterocyclic diazoles on iron surfaces. The effect of these compounds on the corrosion of iron in HCl was studied. Based on our XPS and VSI results we propose that a good inhibition is obtained only when an insoluble complex forms on the surface or a chemical compound with low hydroxide content is present. This sustains the hypothesis that the positively charged ions such as protonated nitrogen heterocyclic compounds might absorb onto the surface via negatively charged anions (e.g. Cl - ) rather than forming a metal-inhibitor complex.

Single-walled carbon nanotube (SWNT) growth using [Fe 33 -O)(µ-O 2 CR) 6 (L) 3 ] n + complexes as catalyst precursors

Ramon Colorado, Jr., Douglas Ogrin, Benji Maruyama, Mark J. Pender, Richard E. Smalley, and Andrew R. Barron, Department of Chemistry, Rice University, Houston, TX 77005-1892

We will present the vapor-liquid-solid (VLS) growth of SWNTs from oxo-hexacarboxylate-tri-iron precursors, [Fe 3 O(O 2 CCH 3 ) 6 (EtOH) 3 ] (1) and [Fe 3 O(O 2 CCH 2 OMe) 6 (H 2 O) 3 ][FeCl 4 ] (2), on spin-on-glass surfaces, using C 2 H 4 /H 2 (750 °C) and CH 4 /H 2 (800 and 900 °C) growth conditions. The SWNTs have been characterized by AFM, SEM, and Raman spectroscopy. The characteristics of the SWNTs are found to be independent of the identity of the precursor complex or the solvent from which it is spin-coated. The as grown SWNTs show a low level of side-wall defects and have an average diameter of 1.2-1.4 nm with a narrow distribution of diameters. We will discuss the effects of the growth temperatures on the observed yields and lengths of the SWNTs. We have demonstrated that spin coating of molecular precursors allows for the formation of catalyst nanoparticles suitable for growth of SWNTs with a high degree of uniformity in the diameter, without the formation of preformed clusters of a set diameter.

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