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19 results on '"Pavlik, Christopher"'

17. Polymer-Mediated Reactions. A Nazarov-Like Cyclization.

Author

Pavlik, Christopher, Morton, Martha D., Invernale, Michael A., Berghorn, Ian D., Sotzing, Gregory A., and Smith, Michael B.

Subjects
*POLYMERS, *CHEMICAL reactions, *HYDROCARBONS, *RING formation (Chemistry), *REARRANGEMENTS (Chemistry)
Abstract

The polymer PEDOT+ mediates a Nazarov-like cyclization of dienones, in an heterogeneous system and in hydrocarbon solvents. The polymer-mediated reactions show clear differences in product formation when compared to the same reaction with tosic acid, or when compared to reports in the literature. Comparable or improved yields are observed, as well as the ability to give a Nazarov product in cases where treatment with acid fails to give cyclization, or leads to an undesirable rearrangement. In addition, the ability to recycle the polymer makes this a potentially useful protocol for an important organic chemical reaction. [ABSTRACT FROM AUTHOR]

Published
2011
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18. Polymer-Mediated Pinacol Rearrangements.

Author

Pavlik, Christopher, Morton, Martha D., and Smith, Michael B.

Subjects
*PINACOL rearrangement, *PYRROLES, *KETONES, *ALDEHYDES, *LEWIS acids, *HYDROCARBONS, *POLYMERS
Abstract

Both poly(3,4-ethylenedioxythiophene) and poly(pyrrole) mediate a pinacol rearrangement of 1,2-diols. The yields of ketone or aldehyde products are comparable to those observed for treatment with mineral acids or Lewis acids. The advantage of this protocol is a two-phase reaction medium in hydrocarbon solvents that allows facile recovery of the products by simple filtration of the polymer and removal of solvents. Both the polymer and the hydrocarbon solvent may be recovered and used in subsequent reactions. [ABSTRACT FROM AUTHOR]

Published
2011
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19. Tumor hypoxia fluorescence imaging using 2-nitroimidazole bis-carboxylic acid indocyanine dye conjugate

Author

Biswal, Nrusingh C., Pavlik, Christopher, Smith, Michael B., Aguirre, Andres, Zanganeh, Saeid, Xu, Yan, Kuhn, Liisa T., Claffey, Kevin P., and Zhu, Quing

Abstract

We present tumor hypoxia mapping by diffuse optical fluorescence tomography. A novel 2-nitroimidazole bis-carboxylic acid indocyanine dye conjugate has been developed for tumor-targeted hypoxia fluorescence imaging. The hypoxia probe has been evaluated in-vitro using 4T1 tumor cell lines and in-vivo tumor targeting in mice. In-vivo tumor targeting in six mice demonstrated that a measured half-life of 2-nitroimidazole-indocyanine dye wash out in the tumor was significantly longer (112±32.37 minutes) than that of bis-carboxylic acid indocyanine dye (69.75±14.01 minutes). The bis-carboxylic acid indocyanine dye was completely washed out from the tumor site within 3-5 hours post-injection, but 2-nitroimidazole-ICG remained for up to 21 hours in the tumor site. Near infrared fluorescence images of mice tumors showed a 2.6-fold contrast of dye uptake with hypoxic conjugate injection (7.46±1.68 M) compared to that with indocyanine dye injection (2.9±0.60 M). The in-vitro cell studies were performed to assess fluorescence labeling comparing hypoxia to normoxia conditions. A fluorescence emission ratio of 2.5-fold was found between the cells treated with the 2-nitroimidazole-indocyanine dye and incubated under hypoxia compared to the cells in normoxia condition. Hypoxia specificity was also confirmed when compared to cells treated with unconjugated indocyanine dye alone. Fluorescence images acquired using a Li-COR scanner from harvested tumor samples support the in vivo monitoring and imaging results.

Published
2011
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