Palladium-catalyzed intermolecular aminocarbonylation of alkenes: efficient access of ß-amino acid derivatives.

A novel palladium-catalyzed intermolecular aminocarbonylation of alkenes has been developed in which the employment of hypervalent iodine reagent can accelerate the intermolecular aminopalladation, which thus provides the successful catalytic transformation. The current transformation presents one of the most convenient methods to generate ß-amino acid derivatives from simple alkenes.

Carbon nanotube-bilirubin oxidase bioconjugate as a new biofuel cell label for self-powered immunosensor.

We demonstrated a biofuel cells (BFCs)-based self-powered sensing system for the detection of Nε-(carboxymethyl)lysine (CML), in which the bilirubin oxidase (BOD)-carbon nanotube (CNT) bioconjugate modified with antibody acted as a biocatalyst for enhancing O2 reduction in the biocathode, as well as the transducing enzyme for signaling magnification. With an increase in the concentration of CML, the amount of BOD labels on biocathode surface increases, thus leading to the higher output of the as-prepared BFCs. This novel BFCs-based self-powered sensor showed a wide linear range for analyzing CML from 1 nM to 100 µM with a detection limit of 0.2 nM, which was 50 times more sensitive than that determined from the conventional ELISA. Most importantly, our new self-powered sensing platform can determine the level of CML in serum samples from multiple healthy donors and multiple sclerosis patients, being well in accordance with that from the commercial ELISA analysis.

Gas-phase fluorine migration reactions in the radical cations of pentafluorosulfanylbenzene (Aryl-SF5) and benzenesulfonyl fluoride (Aryl-SO2F) derivatives and in the 2,5-xylylfluoroiodonium ion.

The gas-phase reactions of Aryl-SF5(·+) and Aryl-SO2F(·+) have been studied with the electron ionization tandem mass spectrometry. Such reactions involve F-atom migration from the S-atom to the aryl group affording the product ion Aryl-F(·+) by subsequent expulsion of SF4 or SO2, respectively. Especially, the 4-pentafluorosulfanylphenyl cation 4-SF5C6H4(+) (m/z 203) from 4-NO2C6H4SF5(·+) by loss of ·NO2 could occur multiple F-atom migration reactions to the product ion C6H4F3(+) (m/z 133) by loss of SF2 in the MS/MS process. The gas-phase reactions of 2,5-xylylfluoroiodonium (pXyl-I(+)F, m/z 251) have also been studied using the electrospray tandem mass spectrometry, which involve a similar F-atom migration process from the I-atom to the aryl group giving the radical cation of 2-fluoro-p-xylene (or its isomer 4-fluoro-m-xylene, m/z 124) by reductive elimination of an iodine atom. All these gas-phase F-atom migration reactions from the heteroatom to the aryl group led to the aryl-F coupling product ions with a new formed C(Aryl)-F bond. Density functional theory calculations were performed to shed light on the mechanisms of these reactions.

Synthesis and biological evaluation of hydroxyl-substituted Schiff-bases containing ferrocenyl moieties.

Three new hydroxyl-substituted Schiff-bases containing ferrocenyl moieties were synthesized, and their antioxidant and anticancer activities were evaluated. Among the synthesized hydroxyl-substituted Schiff-bases, compound 1 containing both ferrocenyl and o-dihydroxyl groups exhibits the highest antioxidant and anticancer activities. Flow cytometric analysis showed that compound 1 is capable of disturbing the cancer cell cycle and inducing more cells to be arrested in G2 phase. The excellent biological activities of compound 1 are attributed to the presence of both ferrocenyl and o-dihydroxyl groups. The ferrocenyl moiety has dual functions in compound 1, i.e., increasing the lipophilicity and lowering the redox potentials of o-dihydroxyl groups. In addition, compound 1 could reversibly bind with HSA mainly via a mechanism involving the formation of complexes, in which hydrophobic interaction is the main acting force. Thus, compound 1 containing both ferrocenyl and o-dihydroxyl groups is a potential antioxidant with anticancer activity.

Regioselective palladium-catalyzed intramolecular oxidative aminofluorination of unactivated alkenes.

A novel Pd-catalyzed regioselective intramolecular aminofluorination of unactivated alkenes has been developed, which is an efficient method for the synthesis of a variety of monofluoromethylated nitrogen-containing heterocycles.

Phosphorus-modified poly(styrene-co-divinylbenzene)-PAMAM chelating resin for the adsorption of uranium(VI) in aqueous.

Polyamidoamine (PAMAM) modified poly(styrene-co-divinylbenzene) absorbents carrying phosphorus functional groups (PS-PAMAM-PPA) were prepared and used as adsorbents for the adsorption of uranium(VI) from aqueous solution. Different generations of PAMAM were used for obtaining different chelating resins, PS-PPA, PS-1.0G PAMAM-PPA, PS-2.0G PAMAM-PPA, PS-3.0G PAMAM-PPA and PS-4.0G PAMAM-PPA. The synthesized resins were characterized by FTIR and XPS. The effects of many physio-chemical properties on metal ion adsorption to adsorbent phase, such as solution pH, kinetic studies, initial uranium concentration, temperature, were investigated using batch method. The results showed that the maximum adsorption capacity (99.89 mg/g) was observed at the pH 5.0 and 25°C with initial U(VI) concentration 100mg/L and adsorbent dose 1g/L. PS-1.0G PAMAM-PPA had the largest adsorption capacity for U(VI) compared with other prepared adsorbents. The adsorption kinetics of U(VI) onto PS-1.0G PAMAM-PPA followed the mechanism of the pseudo-second-order equation, indicating that the chemical adsorption was a rate-limiting step. The calculated thermodynamic parameters (ΔG, ΔH, ΔS) stated that the adsorption of U(VI) onto PS-1.0G PAMAM-PPA were spontaneous, endothermic and feasible. The adsorption isotherms obeyed the Langmuir isotherm models. The desorption studies showed that PS-1.0G PAMAM-PPA could be used repeatedly and adsorption and desorption percentage did not have any noticeable loss after 27 cycles in a fixed bed.