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A method for the synthesis of enantiopure eight-membered nitrogen heterocycles has been developed through diastereoselective cross-coupling of 2-iodobiphenyls with 2-bromobenzylamines. The products represent a novel type of chiral scaffold, which feature easy modification and high configurative stability and have the potential to be applied in asymmetric synthesis. Palladacycles that were formed via the C–H activation of 2-iodobiphenyls should act as the intermediates. The reaction provides a new strategy for the synthesis of medium-sized ring compounds. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed cross-coupling reaction of aryl halides with 2-chlorobenzoic acids has been developed. The reaction forms C(sp3), C(sp2)-palladacycles through C(sp3)–H activation. The palladacycles react with 2-chlorobenzoic acids through two successive C–C cross-couplings, and two C–C bonds are formed with high chemoselectivity. The reaction provides an innovative method for the synthesis of 9,10-dihydrophenanthrenes. [ABSTRACT FROM AUTHOR]

A Pd(II)-catalyzed intermolecular C–H silylation reaction initiated by aminopalladation has been developed. The C–H bonds were activated by an alkyl Pd(II) species generated through aminopalladation and then disilylated with hexamethyldisilane to form disilylated indolines as the final products. The reaction provides a new method for the introduction of silyl groups into complex organic molecules. [ABSTRACT FROM AUTHOR]

Carbon black (CB) has a wide range of industrial applications and recently has been used as the basic model for environmental health studies on airborne particulate matters (PM). Exposure characterization of CB is always the first and most important step towards a better understanding of its effects on human health. However, efforts were largely limited by the lack of valid methods capable of quantifying CB in biological samples. Here, we developed a new method based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for CB quantification in bio-samples, with a detection limit of 4.3 ng. The method is so economical and convenient that it can be performed in most biology labs. The application of the method was successfully demonstrated in three different cell models (mouse macrophage cells (Raw264.7), human epithelial cells (A549) and mouse mesenchymal stem cells (MSC)) and the results showed that the uptake rates decrease in the order of MSC > Raw264.7 > A549. The surprisingly highest uptake rate of MSC deserves further investigation. The novel method provides a complementary quantitative tool to the use of conventional methods such as radioactive and fluorescent labeling and may facilitate related toxicological studies. [ABSTRACT FROM AUTHOR]

A series of Cr-doped Bi4Ti3O12/Bi2Ti2O7 (BTO) heterostructure fibers have been synthesized via a one-step, facile and economical electrospinning/calcination process. SEM and TEM results reveal that the diameters of the as-prepared fibers are 100 ± 30 nm. The light adsorption of Bi4Ti3O12 and Bi2Ti2O7 in the fibers has been remarkably improved by Cr doping. With increased Cr doping, XRD and XPS show that the amount of Bi2Ti2O7 increases in the fibers. As a result, the Bi4Ti3O12/Bi2Ti2O7 heterojunction structure is enhanced, which further promotes the charge separation of photogenerated charge carriers. Photocatalytic tests indicated that the as-prepared Cr-doped Bi4Ti3O12/Bi2Ti2O7 fibers exhibit good photocatalytic activity for photodegradation of methyl orange (MO) under visible-light irradiation. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed cross-coupling reaction of aryl halides with 2-chlorobenzoic acids has been developed. The reaction forms C(sp3), C(sp2)-palladacycles through C(sp3)-H activation. The palladacycles react with 2-chlorobenzoic acids through two successive C-C cross-couplings, and two C-C bonds are formed with high chemoselectivity. The reaction provides an innovative method for the synthesis of 9,10-dihydrophenanthrenes.

Protein phosphorylation plays an important role in many significant cellular processes, and has thus gained tremendous interest in the field of proteomics. The electro-active tyrosine residue, as an important receptor of phosphorylation in proteins, exhibits electro-inactivity after being phosphorylated on the hydroxy group of its aromatic ring. In this study, the electrochemical oxidation of tyrosine on indium tin oxide (ITO) electrodes was catalyzed with an electron mediator Os(bpy)(3)(2+) (bpy = 2,2'-bipyridine) and was employed as a signal reporter to differentially detect non-phosphorylated and phosphorylated peptides. A short, tyrosine-containing peptide glu-glu-glu-glu-glu-tyr (EY-6) was immobilized on an ITO surface using the layer-by-layer self-assembly method, and was detected by cyclic voltammetry in an Os(bpy)(3)(2+) solution. The limit of detection was about 0.23 microg mL(-1) EY-6 in solution. The phosphorylated peptide glu-glu-glu-glu-glu-tyr-OP (EY-6P) did not produce an appreciable oxidation current on the electrode. Surface plasmon resonance measurements revealed that the amount of EY-6 and EY-6P adsorbed on the sensor chip surface was 269 and 378 pg mm(-2), respectively. The poly(glu, tyr) (4 : 1) peptide, a protein tyrosine kinase substrate, was also detected by the same approach, with a detection limit of 0.65 microg mL(-1). This new approach offers the possibility of label-free and on-chip detection of protein tyrosine kinase activity.