February 9th, 2010
In the current work we present our preliminary evaluation of a new protein labeling strategy, namely oxidation labeling. We found that a bis(2-picolyl) amine analogue coordinating Cu
+ was able to oxidize histidine to oxo-histedine in a small peptide by generating reactive oxygen species upon exposure to hydrogen peroxide. The bis(2-picolyl) amine unit was then incorporated into the natural product tautomycin via an oxime linker. The compound, which showed good activity toward protein phosphatase 1γ (PP1γ), will be used in oxidation labeling studies with PP1γ.
http://dx.doi.org/10.1016/j.tet.2009.12.036
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February 9th, 2010
3,5-Bis(trimethylsilylethynyl)-4,4-difluoro-8-(4-tolyl)-4-bora-3a,4a-diaza-
s-indacene [BODIPY(CCTMS)
2] has been synthesized by coupling of 3,5-dibromo-4,4-difluoro-8-(4-tolyl)-4-bora-3a,4a-diaza-
s-indacene with trimethylsilylacetylene under pd(0) coupling conditions. The BODIPY(CCTMS)
2 was used as a selective colourimetric and fluorescent chemodosimeter for fluoride ion, following the F
− ion induced cleavage of trimethylsilyl group, the protecting group of ethyne functionality by monitoring the changes in UV–vis and fluorescence properties. The dosimeter BODIPY(CCTMS)
2 display clear changes in colour, absorption and emission bands selectively for F
− ion over other anions such as Cl
−, Br
−, I
−, ClO
4− and HPO
42−.
http://dx.doi.org/10.1016/j.tet.2009.12.039
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February 9th, 2010
Adamantane-dipyrromethane (AdD) receptors [di(pyrrole-2-yl)methyladamantane (
1), 2,2-di(pyrrole-2-yl)adamantane (
2), 1,3-bis[di(pyrrole-2-yl)methyl]adamantane (
3), 2,2,6,6-tetra(pyrrole-2-yl)adamantane (
4)] form complexes with F
−, Cl
−, Br
−, AcO
−, NO
3−, HSO
4−, and H
2PO
4−. The association constants of the complexes were determined by
1H NMR titrations, whereas the geometries of complexes
1·F− (2:1),
2·F− (2:1),
2·Cl− (2:1),
2·AcO− (2:1), and
4·F− (1:1) were determined by X-ray structural analysis. The most stable complexes are of 2:1 stoichiometry with F
− and AcO
−. The stability constants are in accordance with the anion basicity and the ability of AdD receptors to place the hydrogen bonding donor groups in a tetrahedral fashion around anions. The binding energies of the complexes between receptors
1–
4 and F
− anion are calculated using quantum chemical methods. The calculated results show that the solvent polarity is important for the complexation of fluoride ion with AdD receptors
1–
4.
http://dx.doi.org/10.1016/j.tet.2010.01.018
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February 9th, 2010
Two 4,5-disubstituted-1,8-naphthalimide derivatives
1 and
2 were synthesized as ratiometric fluorescent and colorimetric sensors for Cu
2+, respectively. In 100% aqueous solutions of
1, the presence of Cu
2+ induces a strong and increasing fluorescent emission centered at 478 nm at the expense of the fluorescent emission of
1 centered at 534 nm. Compound
2 senses Cu
2+ by means of a colorimetric (primrose yellow to pink) method with a thorough quench in emission attributed to the deprotonation of the secondary amine conjugated to the naphthalimide fluorophore.
1-Cu
2+ and
2-Cu
2+ sense cyanide in ratiometric way via colorimetric and fluorescent changes.
http://dx.doi.org/10.1016/j.tet.2010.01.008
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February 9th, 2010
A new low molecular mass organogelator
1 containing 2-(2′-hydroxyphenyl)benzoxazole (HPB) group with long alkyl chain was synthesized by the reaction with 5-amino-2-(2′-hydroxy-4′-methylphenyl)benzoxazole and dodecyl isocyanate in THF at room temperature. The reversible gelation ability of
1 was investigated using a heating-cooling method in various organic solvents. The stable organogel was formed from carbon tetrachloride or from cyclohexane at the concentration as low as 0.9%. The self-assembled supramolecular gel structure formed by non-covalent bonding was confirmed with field emission-scanning electron microscope (FE-SEM) exhibiting fibril- or ribbon-shaped structure depending on the solvent used. Regarding the aggregation-induced emission enhancement (AIEE) phenomenon, the optical properties were investigated in its solution and gelled state. The detecting properties of resulting organogel toward nerve gas simulant were monitored by UV–vis and fluorescence spectroscopy. Both color change from colorless to greenish yellow and disruption of gel structure resulting from alteration in intermolecular forces were observed upon the exposure to nerve gas simulant.
http://dx.doi.org/10.1016/j.tet.2010.01.006
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February 9th, 2010
The supramolecular organogelation of alcohols was observed in relatively hydrophobic amphiphiles with a short oligo(ethylene glycol) unit and three long alkyl chains at room temperature, while the hydrogelation occurred in more hydrophilic gelators with a longer poly(ethylene glycol) unit and two long alkyl chains at various temperatures. When a hot aqueous solution of some of the synthetic hydrogelators was cooled down, the supramolecular hydrogel was formed at room temperature. In some other amphiphiles with less intermolecular interactivity in water at room temperature, a reverse phase transition of sol to gel was observed by elevating the temperature of their aqueous systems, especially below a physiological temperature, 37 °C. The supramolecular hydrogelation at a low or high temperature was dependent on a slight molecular modification of the synthetic amphiphiles.
http://dx.doi.org/10.1016/j.tet.2010.01.002
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February 9th, 2010

Organic Letters, Volume 0, Issue 0, Articles ASAP (As Soon As Publishable).
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February 9th, 2010

The Journal of Organic Chemistry, Volume 0, Issue 0, Articles ASAP (As Soon As Publishable).
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