Oxidative entry to α-oxy N-acyl aminals and hemiaminals: efficient formation of 2-(N-acylaminal) substituted tetrahydropyrans

An efficient new method to synthesize α-oxy N-acyl aminals and hemiaminals in a single step from readily synthesized N-acyl enamines has been developed using PhI(OAc)₂ as the oxidant. The reaction conditions are very mild and the products are obtained in good yields (65-92%). A possible mechanistic pathway is laid out.     

Quinine/selectfluor combination induced asymmetric semipinacol rearrangement of allylic alcohols: an effective and enantioselective approach to alpha-quaternary beta-fluoro aldehydes

A quinine/Selectfluor combination inducing rearrangement reaction of allylic alcohols was discovered, which involved a moderate yield with good enantioselective construction of alpha-quaternary carbon center and beta-fluoro aldehyde under base condition.     

Electrospun nanofibers of poly（vinyl pyrrolidone）/Eu^3＋ and its photoluminescence properties

Nanofibers of poly（vinyl pyrrolidone） （PVP）/Eu^3＋ with diameters of 300-900 nm were prepared by using sol-gel processing and electrospinning technique. The products were characterized by scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FT-IR）, and photoluminescence （PL）. The results indicated that, Eu^3＋ was successfully embedded in the onedimensional hybrid nanofibers, and the PVP/Eu^3＋ hybrid nanofibers had favorable photoluminescence properties.     

Charge transport properties of tris(8-hydroxyquinolinato)aluminum(III): why it is an electron transporter

The charge transport properties of mer-tris(8-hydroxyquinolinato)aluminum(III) (mer-Alq), which is the most widely used electron transport material in OLED, were investigated by quantum chemistry calculations within the framework of the charge hopping model and Marcus electron transfer theory. Internal reorganization energies of 0.276 and 0.242 eV were calculated by the DFT-B3LYP method employing a 6-31 G* basis set for the electrons lambdai(e) and holes lambdai(h), respectively. The relative distances and orientations of Alq molecules in amorphous film were simulated by those in the beta-phase. The intermolecular charge-transfer integrals, Hda(h) and Hda(e), along all 14 hopping pathways were then calculated by the Koopmans Theorem in conjunction with the Hartree-Fock method employing a 6-31 G* basis set as well as by the direct coupling method. The results showed that there were some Hda(e) that were 1 order of magnitude larger than any Hda(h), because hopping pathways with effective overlaps of LUMOs can occur and, thus, large Hda(e). On the other hand, effective overlap of HOMO was absent in all pathways, resulting in a relatively small Hda(h). This difference in the magnitudes of Hda(e) and Hda(h) would predict a 2 orders of magnitude difference in the electron-transfer rate constants and account for the observed 2 orders of magnitude difference in the mobilities of electrons and holes.     

2020 Roadmap on two-dimensional nanomaterials for environmental catalysis

This roadmap demonstrates a series of two-dimensional nanomaterials, such as graphene, black phosphorus, oxides, layered double hydroxides, chalcogenides, bismuth-based layered compounds, MXenes, metal organic frameworks, covalent organic frameworks, and others, for environmental catalysis.     

Synthesis and antimicrobial activity of a perfluoroalkyl-containing quaternary ammonium salt

A novel perfluoroalkyl-containing quaternary ammonium salt 5 was designed and synthesized. Consequently, the antimicrobial activities of compound 5 were measured with Escherichia coli 8099 as a Gram-negative strain and Staphylococcus aureus ATCC 6538 as a Gram-positive strain. Both the minimum inhibitory concentration (MIC, the lowest concentration of compound 5 that inhibits microbial growth) values of quaternary ammonium salt 5 against Escherichia coli 8099 and Staphylococcus aureus ATCC 6538 were 7.8 μg/ml.     

Morin applied in speciation of aluminium in natural waters and biological samples by reversed-phase high-performance liquid chromatography with fluorescence detection

A reversed-phase high-performance liquid chromatographic method with fluorescence detection for the determination of labile monomeric aluminium has been developed through pre-column complexation using morin as the analytical reagent. The highly fluorescent aluminium-morin complex (excitation wavelength 418 nm, emission wavelength 490 nm) was separated on a Spherisorb ODS 2 column with an eluent consisting of 30% methanol and 70% water (pH 1.0 with perchloric acid). The most remarkable point of this protocol was that only the most toxic aluminium species, that is, free aqua-aluminium ion and its monomeric hydroxo complex ions, selectively respond among various aluminium complexes. This strategy has been successfully applied to direct fractionation of the toxic aluminium in natural waters and biological samples without any pretreatment.     

Tetra‐μ‐acetato‐κ2O:O′‐bis[(4‐phenylpyridine‐κN)copper(II)]

The title compound, [Cu₂(C₂H₃O₂)₄(C₁₁H₉N)₂] or [Cu₂(MeCO₂)₄(phpy)₂] (phpy is 4‐phenyl­pyridine), consists of centrosymmetric dimers in which the Cu^II atoms display a square‐pyramidal CuO₄N coordination, with four acetate O atoms in the basal plane [Cu—O 1.975 (3)–1.987 (3) Å] and the phpy N atom in the apical position [Cu—N 2.150 (3) Å]. The Cu atoms are 2.654 (1) Å apart and are bridged by four acetate groups. The discrete dimers are extended into a three‐dimensional supramolecular array through intermolecular π–π‐stacking interactions.     

LC Determination of 4-Bromoaniline in Green Algae Chlamydomonas reinhardtii After Continuous-Flow Microextraction

In this study, the determination of 4-Bromoaniline (4-BA) in green algae Chlamydomonas reinhardtii (C. reinhardtii) was investigated by applying continuous-flow microextraction (CFME) combined with high-performance liquid chromatography (HPLC). Continuous-flow microextraction was conducted in a homemade glass chamber, i.e. the sample solution flowed through a constant volume drop of solvent in the chamber at a constant flow rate. The effects of different factors on extraction efficiencies were also investigated and these factors included the kind of extraction solvent, solvent drop volume, sample flow rate, extraction time and addition amount of salt. Under the optimum extraction conditions (extraction solvent, carbon tetrachloride; solvent drop volume, 3.5 μL; sample flow rate, 1.0 mL min⁻¹; extraction time, 10 min; no addition of salt), the calibration plot was set up by plotting peak area against a series of 4-Bromoaniline concentrations (0.01–10 μg mL⁻¹) in aqueous solution. The correlation coefficient (r) was 0.9990. The limit of detection (LOD) was 0.6 ng mL⁻¹. The precision of this method was obtained by successive five time analyses of 100-ng mL⁻¹ standard solution of 4-Bromoaniline, and the relative standard deviation (RSD) was 3.5%. The concentration factor was calculated by the ratio of peak area of the analyte obtained after and before extraction and found to be 10.6. 4-Bromoaniline residues in Chlamydomonas. reinhardtii cells and tap water samples were satisfactorily analyzed according to the method described above.     

Identification of differentially expressed proteins between human hepatoma and normal liver cell lines by two-dimensional electrophoresis and liquid chromatography-ion trap mass spectrometry

In the previous study, the proteomes of the human hepatoma cell line BEL-7404 and the normal human liver cell line L-02 were separated by high resolution two-dimensional electrophoresis (2-DE). Image analysis revealed that 99 protein spots showed quantitative and qualitative variations that were significant (P < 0.01) and reproducible. Here we report the identification results of some of these protein spots. Protein spots excised from 2-D gels were subjected to in-gel digestion with trypsin, and the resulting peptides were measured by microbore high performance liquid chromatography - ion trap - mass spectrometry (LC-IT-MS) to obtain the tandem mass (MS/MS) spectra. Twelve protein spots were identified with high confidence using SEQUEST with uninterpreted MS/MS raw data. Besides inosine-5'-monophosphate dehydrogenase 2, heat shock 27 kDa protein, calreticulin and calmodulin, whose expression was elevated in hepatoma cells, glutathione-S-transferase P was identified from hepatoma cells in which its level was 18-fold higher compared to human liver cells. Two spots were identified as the homologs of reticulocalbin for the first time in hepatoma cells and their expression increased compared to liver cells. However, tubulin beta-1 chain and natural killer cell enhancing factor B were downregulated in hepatoma cells. A tumor suppressing serpin, maspin precursor, was identified from one spot whose quantity was much higher in the normal liver cell line. More interestingly, epidermal fatty acid-binding protein (E-FABP) and fatty acid-binding protein, adipocyte-type (A-FABP), were detected in liver cells but not in hepatoma cells. The functional implication of the identified proteins was discussed.