Facile Synthesis of 3‐Hydroxyglutamic Acids via Cyanation of Chiral N‐Acyliminium Cation Derived From (S)‐Malic Acid

Facile synthesis of 3‐hydroxyglutamic acids via cyanation of an N‐acyliminium intermediate derived from (S)‐malic acid is described. The chiral cyclic imide derived from (S)‐malic acid was converted to an acetoxylactam by reduction with sodium borohydride followed by acetylation. The obtained acetoxylactam was treated with trimethylsilyl cyanide in the presence of boron trifluoride etherate to give the corresponding cyanolactam in high yield, even though the diastereoselectivity of the cyanation reaction was moderate. The diastereomers of the cyanolactam were chromatographically separable and were independently converted to (2R,3S)‐ and (2S,3S)‐3‐hydroxyglutamic acids.     

Molecular sieves 4A work to mediate the catalytic metal enolization of nucleophile precursors: application to catalyzed enantioselective Michael addition reactions

Molecular sieves 4A (MS4A) work effectively as base leading to catalytic generation of nickel(II) enolate or nitronate nucleophiles through deprotonation of the α-hydrogen atom of nucleophile precursors on treatment with a catalytic amount of chiral nickel(II) ions. The resulting reactive intermediates can be successfully trapped with α,β-unsaturated carbonyl electrophiles to produce the corresponding Michael adducts in good yields with high enantioselectivities.     

Structure,energy and solute segregation behaviour of [110] symmetric tilt grain boundaries in yttria-stabilized cubic zirconia

Yttria-stabilized cubic zirconia bicrystals with [110] symmetric tilt grain boundaries are systematically fabricated by the diffusion bonding method. It is revealed that the grain-boundary atomistic structures, excess energies and solute segregation behaviours are strongly dependent on the macroscopic geometries of the boundaries. High-resolution transmission electron microscopy combined with lattice statics calculations suggests that the grain-boundary structures are characterized by the accumulation of coordination-deficient cation sites at their cores, whose densities have a clear correlation with excess energies and amounts of solute segregation. The orientation dependence of grain-boundary properties in cubic zirconia can thus be linked and understood via local grain-boundary atomistic structures with the characteristic miscoordinated cation sites.     

Absorption spectroscopy of uranium plasma for remote isotope analysis of next-generation nuclear fuel

CdSe/Se multilayer thin films were prepared using sequential thermal evaporation technique by varying the thickness of selenium sublayers. Identifying the prominent peaks observed in the XRD spectra of the top layer CdSe which corresponds to the (100) plane with wurtzite structure, the average size of the crystallites was calculated for the CdSe nanocrystals. Experimentally measured band gaps are larger than bulk band gap of CdSe. This confirms the presence of spin-orbit splitting of energy levels. Size of the crystallites was then calculated with the theoretical prediction of the effective mass approximation model (i.e., Brus model). It resulted in that the diameters of crystallites were much smaller than the Bohr exciton diameter (11.2 nm) of CdSe. Thus the structural and optical properties of CdSe/Se multilayer thin films reveal the effect of quantum confinement of CdSe crystallites in Se matrix for various sublayer thicknesses. Confinement effect is more pronounced while sublayer thickness of selenium increases.     

Formation and characterization of the Cu2O overlayer on Zn-terminated ZnO(0 0 0 1)

Low-energy electron diffraction, X-ray photoelectron spectroscopy and synchrotron-radiation-excited angle-resolved photoelectron spectroscopy have been used to characterize Cu-oxide overlayers on the Zn-terminated ZnO(0 0 0 1) surface. Deposition of Cu on the ZnO(0 0 0 1)-Zn surface results in the formation of Cu clusters with (1 1 1) top terraces. Oxidation of these clusters by annealing at 650 K in O₂ atmosphere (1.3 × 10⁻⁴ Pa) leads to an ordered Cu₂O overlayer with (1 1 1) orientation. Good crystallinity of the Cu₂O(1 1 1) overlayer is proved by energy dispersion of one of Cu₂O valence bands. The Cu₂O(1 1 1) film exhibits a strong p-type semiconducting nature with the valence band maximum (VBM) of 0.1 eV below the Fermi level. The VBM of ZnO at the Cu₂O(1 1 1)/ZnO(0 0 0 1)-Zn interface is estimated to be 2.4 eV, yielding the valence-band offset of 2.3 eV.     

Synthesis and properties of novel extended BODIPYs with rigid skeletons

Novel extended BODIPYs fused with bicyclo rings were synthesized from bicyclopyrroles by combining Knoevenagel condensation, Suzuki coupling, and O-chelation. The absorption maxima of the BODIPYs ranged from the visible to near-infrared region and the compounds showed good solubility in organic solvents. The solubility of the bicycloBODIPY with 2-naphthyl groups at the α-position of the pyrrole units was particularly high. Heating converted distyrylBODIPY with bicyclo[2.2.2]octene to benzoBODIPY with absorption (748.5?nm) and fluorescence (775.0?nm) in the near-infrared region.     

Phytonutrients,Colorant Pigments,Phytochemicals, and Antioxidant Potential of Orphan Leafy Amaranthus Species

The underutilized Amaranthus leafy vegetables are a unique basis of pigments such as β-cyanins, β-xanthins, and betalains with radical scavenging capacity (RSC). They have abundant phytonutrients and antioxidant components, such as pigments, vitamins, phenolics, and flavonoids. Eight selected genotypes (four genotypes from each species) of underutilized Amaranthus leafy vegetables were evaluated for phytonutrients, pigments, vitamins, phenolics, flavonoids, and antioxidants in a randomized complete block design under ambient field conditions with three replicates. The studied traits showed a wide range of variations across eight genotypes of two species of Amaranthus leafy vegetables. The highest fat, β-xanthins, K, dietary fiber, Mg, β-cyanins, Mn, chlorophyll ab, Zn, TP, TF, betalains, chlorophyll a content, and (RSC) (DPPH) and RSC (ABTS⁺) were obtained from A. tricolor accessions. Conversely, the highest protein, Cu, carbohydrates, Ca, and chlorophyll b content were obtained from A. lividus accessions. The highest dry matter, carotenoids, Fe, energy, and ash were obtained from A. tricolor and A. lividus. The accession AT2 confirmed the highest vit. C and RSC (DPPH) and RSC (ABTS+); AT5 had the highest TP content; and AT12 had the highest TF content. A. tricolor accessions had high phytochemicals across the two species, such as phytopigments, vitamins, phenolics, antioxidants, and flavonoids, with considerable nutrients and protein. Hence, A. tricolor accessions can be used as high-yielding cultivars comprising ample antioxidants. The correlation study revealed that vitamin C, pigments, flavonoids, β-carotene, and phenolics demonstrated a strong RSC, and showed a substantial contribution to the antioxidant potential (AP) of A. tricolor. The investigation exposed that the accessions displayed a plentiful origin of nutritional values, phytochemicals, and AP with good quenching ability of reactive oxygen species (ROS) that provide enormous prospects for nourishing the mineral-, antioxidant-, and vitamin-threatened community.