- Fullerene modification of gold electrodes and gold nanoparticles based on application of aromatic thioacetate-functionalized C60
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A new procedure for the synthesis of S-acetyl-derivatized fullerene is described. The deprotected aromatic S-acetyl-derivatized fullerene was employed for efficient modification of a gold electrode and gold nanoparticles. The proposed deposition procedure of fullerene derivative on Au surfaces allows the control of the thickness of the self-assembled fullerene layer. The modified surfaces were characterized by electrochemical methods and X-ray photoelectron spectroscopy (XPS). Functionalized fullerenes largely retain favorable redox electronic properties, behaving as an electron sink and revealing 4 reversible sequential 1e electrode processes at slightly more negative potentials than those observed for unsubstituted C60. For the first time, fullerene-capped gold nanoparticles were obtained by a two-step ligand exchange procedure involving substitution of alkanethiol with thiolated fullerene derivative following the synthesis of alkanethiol capped nanoparticles. The ligand exchange procedure was very efficient-the number of fullerene moieties per single gold nanoparticle was found to be as high as 30. This journal is
- Piotrowski, Piotr,Pawlowska, Joanna,Pawlowski, Jan,Opuchlik, Lidia Jagoda,Bilewicz, Renata,Kaim, Andrzej
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- 2-AZETIDINONES AS ANTI-HYPERCHOLESTEROLEMIC AGENTS
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The instant invention provides novel cholesterol absorption inhibitors of Formula I and the pharmaceutically acceptable salts and esters thereof. The compounds are useful for lowering plasma cholesterol levels, particularly LDL cholesterol, and for treati
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Page/Page column 27
(2010/02/11)
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- Thiol-Derivatized Porphyrins for Attachment to Electroactive Surfaces
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The attachment of porphyrin monomers and multiporphyrin arrays in controlled architectures on electroactive surfaces opens many opportunities for electrochemical studies. Toward this goal, we have developed routes for the preparation of thiol-derivatized porphyrin monomers and porphyrin building blocks that require minimal or no handling of free thiols. Routes to S-protected p-thiobenzaldehydes and m-(thiomethyl)benzaldehydes have been developed. Two sets of meso-substituted porphyrins with variation in electrochemical potentials have been prepared for vertical or horizontal orientation with respect to the electroactive surface. In one set, each porphyrin bears one S-protected p-thiophenyl unit and substituents at the three remaining meso-positions. In the other set each porphyrin possesses four S-protected m-(thiomethyl)phenyl units. Tuning the electrochemical potential in the former set has been achieved by variation of the meso substituents (mesityl, 2,4,6-trimethoxyphenyl, n-pentyl, pentafluorophenyl) and in the latter set by variation of the central metal (Zn, Cu, Co, Ag). Six thiol protecting groups [S-cyano, S-(N-ethylcarbamoyl), S-acetyl, S-(9-anthrylmethyl), S-(2,4-dinitrophenyl), S-pivaloyl] have been found to be compatible with porphyrin formation and metalation with zinc. The S-cyano, S-(N-ethylcarbamoyl), and S-acetyl groups undergo in situ cleavage and/or binding on a gold surface. Of these three, only the S-acetyl protecting group is compatible with the Pd-mediated iodo-ethyne coupling conditions for the preparation of multiporphyrin arrays. Three trans-substituted porphyrin building blocks have been prepared for the synthesis of multiporphyrin arrays that can be attached to an electroactive surface. One porphyrin has two mesityl, one p-iodophenyl, and one p-(S-acetylthio)phenyl substituent for vertical positioning, and two porphyrins each have two m-iodophenyl and two S-protected m-(thiomethyl)phenyl substituents for horizontal positioning. Altogether, 16 free base and 16 metalloporphyrins have been prepared. This work establishes the foundation for preparing diverse thiol-derivatized porphyrin monomers and building blocks.
- Gryko, Daniel T.,Clausen, Christian,Lindsey, Jonathan S.
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p. 8635 - 8647
(2007/10/03)
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