Jing-Kui Yang

Preparation of a novel stable nitroxide based on [60]fulleropyrrolidine and its magnetic properties

A novel stable nitroxide based on C60 integrated into special structures was synthesized through the oxidization of [60]fulleropyrrolidine with m-chloroperbenzoic acid. The magnetic properties of the nitroxide were measured by ESR and a SQUID-magnetometer.

Iridium-catalyzed highly efficient chemoselective reduction of aldehydes in water using formic acid as the hydrogen source

A water-soluble highly efficient iridium catalyst is developed for the chemoselective reduction of aldehydes to alcohols in water. The reduction uses formic acid as the traceless reducing agent and water as a solvent. It can be carried out in air without the need for inert atmosphere protection. The products can be purified by simple extraction without any column chromatography. The catalyst loading can be as low as 0.005 mol% and the turn-over frequency (TOF) is as high as 73 800 mol mol−1 h−1. A wide variety of functional groups, such as electron-rich or deficient (hetero)arenes and alkenes, alkyloxy groups, halogens, phenols, ketones, esters, carboxylic acids, cyano, and nitro groups, are all well tolerated, indicating excellent chemoselectivity.

An unexpected reaction: [2 +1] cycloaddition of [60]fullerene with 4, 4, 5, 5-tetramethylimidazolidine-2-thione and DL-valine

C60 reacted with DL-valine and 4, 4, 5, 5-tetramethylimidazolidine-2-thione in a new reaction to give a new C60 spiro-compound 3 which was characterized by FT-IR, NMR, and FD-mass spectra. The possible reaction mechanism was put forward.

Synthesis and characterization of stable nitroxides based on fullerenes (C60, C70) and their magnetic study

Abstract C 60 or C 70 reacts with 2-aminoisobutyric acid and cyclohexanone in chlorobenzene at refluxing through 1,3-dipolar cycloaddition to give [60]fulleropyrrolidine 1 or [70]fulleropyrrolidine 3 which can be oxidized with MCPBA at room temperature to yield stable nitroxides 2 or 4 . The compounds 1 and 3 were characterized by mass spectrum, FT-i.r., n.m.r. spectra. The compounds 2 and 4 were characterized by mass spectrum, FT-i.r., e.s.r. spectra. The magnetic properties of compounds 2 and 4 were measured by SQUID-magnetometer (MPMC Quantum Design), we found that they were paramagnetic.

Preparation of Two Novel C60 and C70 Fullerene Pyrrolidine Derivatives

Abstract C60 reacted with paraformaldehyde and DL-valine in dry toluene under nitrogen to give a monoadduct. Under the similar conditions,C70 gave a bisadduct. Both products were characterized by FT-IR,UV-Vis,EI-MS and NMR.The studies of the cyclic voltammetry showed that the abilities of donating electron of the products were increased compared to C60 and C70 respectively.

Regioselective alkyl transfer from phosphonium ylides to functionalized polyfluoroarenes

We report an unprecedented alkyl transfer from phosphonium ylides to polyfluoroarenes in a highly regioselective manner. This reaction allows the introduction of a variety of alkyl groups to the para position of functionalized polyfluoroarenes under mild conditions. The process is found to be compatible with several electrophilic functional groups such as carboxyl, ester, amide and cyano groups. NMR spectroscopy studies and deuterated labeling experiments reveal that the reaction proceeds via an SNAr mechanism and the proton that is transferred to the α-carbon of the alkyl group during the last C–P bond breaking step is from water.

Antibody-Free Colorimetric Detection of Total Aflatoxins in Rice Based on a Simple Two-Step Chromogenic Reaction.

The prevalently used immunoassays for fast screening of aftatoxins (AFs) usually cannot meet the requirement for simultaneous determination of total AFs (aflatoxin B1 + aflatoxin B2 + aflatoxin G1 + aflatoxin G2) due to the deficiency of highly group-specific antibodies. This paper describes a two-step chromogenic reaction based method to quantitatively detect total AFs in rice using colorimetric measurement without antibody. In the method, colorless AFs transform into green-colored indophenol products through the reaction with sodium hydroxide and 2,6-dibromoquinone-4-chloroimide (DBQC) successively, allowing selectively determining total AFs up to 3.9 μg/kg over other competitive mycotoxins under optimal conditions by a UV-vis spectrophotometer. In addition, the colorimetric measurement results of the rice samples agree well with that of a standard HPLC method, demonstrating the good reliability and applicability of the method. Uniquely, the method has potential for on-site detection of total AFs in rice when using a nylon membrane-based device.

[(18-Crown-6)K][Fe(1)Cl(1)4]0.5[Fe(2)Cl(2)4]0.5: A Multifunctional Molecular Switch of Dielectric, Conductivity and Magnetic Properties

Multifunctional materials that exhibit different physical properties in a single phase have potential for use in multifunctional devices. Herein, we reported an organic-inorganic hybrid compound [(18-crown-6)K][Fe(1)Cl(1)4 ]0.5 [Fe(2)Cl(2)4 ]0.5 (1) by incorporating KCl and FeCl3 into a 18-crown-6 molecule, which acts as a host of the six O atoms providing a lone pair of electrons to anchor the guest potassium cation, and [FeCl4 ]- as a counterion for charge balance to construct a complex salt. This salt exhibited a one-step reversible structural transformation giving two separate high and low temperature phases at 373 K, which was confirmed by systematic characterizations including differential scanning calorimetry (DSC) measurements, variable-temperature structural analyses, and dielectric, impedance, variable-temperature magnetic susceptibility measurements. Interestingly, the structural transformation was coupled to both hysteretic dielectric phase transition, conductivity switch and magnetic-phase transition at 373 K. This result gives an idea for designing a new type of phase-transition materials harboring technologically important magnetic, conductivity and dielectric properties.

Colorimetric Detection of Cr3+ in Aqueous Solution Based on Cofunctionalized Silver Nanoparticles Modified with 4-Nitrobenzenethiol and 4-Mercaptobenzoic Acid,

A new method has been proposed to realize the visual detection of Cr3+ using 4-nitrobenzenethiol (4-NBT) and 4-mercaptobenzoic acid (4-MBA) modified silver nanoparticles (AgNPs). The presence of Cr3+ induces the aggregation of AgNPs through cooperative metal–ligand interaction, resulting in a color change from bright yellow to purple. Consequently, Cr3+ could be monitored by colorimetric response of AgNPs by a UV-Vis spectrophotometer or even naked eyes. We firstly used ethylene diamine tetraacetic acid (EDTA) as a masking agent to selectively detect Cr3+, and other metal ions have little influence on the Cr3+–AgNPs system. The cofunctionalized AgNPs exhibited a highly sensitive detection limit of Cr3+, which is as low as 5 × 10-9 mol L-1, and the absorbance ratio (A600nm/A387nm) is linear with the concentration of Cr3+ ranging from 5 × 10-9 mol L-1 to 2 × 10-6 mol L-1 with a coefficient of 0.993. Particularly, the sensor has been further evaluated to monitor the concentration of Cr3+ in drinking water, the recovery was in good agreement with those obtained by ICP-MS, indicating that this proposed method is successfully applied in real samples.

Bis(methylthio)ethylenedithiotetrathiafulvalene

The title compound {alternative nomenclature : 2-[4,5-bis(methylthio)-1,3 -dithiol-2-ylidene]-5,6-dihydro-1,3-dithiolo[4,5-b][1,4]dithiine}, C 10 H 10 S 8 , is a molecular crystal with typical values for bond distances and angles. The molecules form columns along the c axis. The intermolecular S...S distances indicate the presence of van der Waals interactions between the columns.