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Achieving efficient catalytic conversion over a heterogeneous catalyst with excellent resistance against leaching is still a grand challenge for sustainable chemical synthesis in aqueous solution. Herein, we devised a single‐atom Pt1/hydroxyapatite (HAP) catalyst via a simple hydrothermal strategy. Gratifyingly, this robust Pt1/HAP catalyst exhibits remarkable catalytic selectivity and catalyst stability for the selective oxidation of C2–C4 polyols to corresponding primary hydroxy acids. It is found that the Pt−(O−P) linkages with strong electron‐withdrawing function of PO43− (Pt1−OPO43− pair active site) not only realize the activation of the C−H bond, but also destabilize the transition state from adsorbed hydroxy acids toward the C−C cleavage, resulting in the sharply increased selectivity of hydroxy acids. Moreover, the strong PO43−‐coordination effect provides electrostatic stabilization for single‐atom Pt, ensuring the highly efficient catalysis of Pt1/HAP for over 160 hours with superior leaching resistance. [ABSTRACT FROM AUTHOR]

Abstract: A nearly‐30‐year‐old unanswered synthetic puzzle, astellatol, has been solved in an enantiospecific manner. The highly congested pentacyclic skeleton of this rare sesterterpenoid, which possesses a unique bicyclo[4.1.1]octane motif, ten stereocenters, a cyclobutane that contains two quaternary centers, an exo‐methylene group, and a sterically encumbered isopropyl trans‐hydrindane motif, makes astellatol arguably one of the most challenging targets for sesterterpenoid synthesis. An intramolecular Pauson–Khand reaction was exploited to construct the right‐hand side scaffold of this sesterterpenoid. An unprecedented reductive radical 1,6‐addition, mediated by SmI2, forged the cyclobutane motif. Last, a strategic oxidation/reduction step provided not only the decisive solution for the remarkably challenging late‐stage transformations, but also a highly valuable unravelling of the notorious issue of trans‐hydrindane synthesis. Importantly, the synthesis of astellatol showcases a rapid, scalable strategy to access diverse complex isopropyl trans‐hydrindane sesterterpenoids. [ABSTRACT FROM AUTHOR]

Background: Microalgae are widely studied for biofuel production. Nevertheless, harvesting step of biomass is still a critical challenge. Bioflocculants have been applied in numerous applications including the low-cost harvest of microalgae. A major bottleneck for commercial application of bioflocculant is its high production cost. Lignocellulosic substrates are abundantly available. Hence, the hydrolyzates of rice stover and corn stover have been used as carbon source to produce the bioflocculant in previous studies. However, the hydrolyzates of biomass required the neutralization of pH before the downstream fermentation processes, and the toxic by-products produced during hydrolysis process inhibited the microbial activities in the subsequent fermentation processes and contaminated the bioflocculant product. Therefore, strains that can secrete plant cell-wall-degrading enzymes and simultaneously produce bioflocculants through directly degrading the lignocellulosic biomasses are of academic and practical interests. Results: A lignocellulose-degrading strain Cellulosimicrobium cellulans L804 was isolated in this study, which can produce the bioflocculant MBF-L804 using untreated biomasses, such as corn stover, corn cob, potato residues, and peanut shell. The effects of culture conditions including initial pH, carbon source, and nitrogen source on MBF-L804 production were analyzed. The results showed that over 80 % flocculating activity was achieved when the corn stover, corn cob, potato residues, and peanut shell were used as carbon sources and 4.75 g/L of MBF-L804 was achieved under the optimized condition: 20 g/L dry corn stover as carbon source, 3 g/L yeast extract as nitrogen source, pH 8.2. The bioflocculant MBF-L804 contained 68.6 % polysaccharides and 28.0 % proteins. The Gel permeation chromatography analysis indicated that the approximate molecular weight (MW) of MBF-L804 was 229 kDa. The feasibility of harvesting microalgae Chlamydomonas reinhardtii and Chlorella minutissima using MBF-L804 was evaluated. The highest flocculating efficiencies for C. reinhardtii and C. minutissima were 99.04 and 93.83 %, respectively. Conclusions: This study shows for the first time that C. cellulans L804 can directly convert corn stover, corn cob, potato residues and peanut shell into the bioflocculants, which can be used to effectively harvest microalgae. [ABSTRACT FROM AUTHOR]

The direct CH annulation of anilines or related compounds with internal alkynes provides straightforward access to 2,3-disubstituted indole products. However, this transformation proceeds with poor regioselectivity in the synthesis of unsymmetrically 2,3-diaryl substituted indoles. Herein, we report the rhodium(III)-catalyzed CH annulation of nitrones with symmetrical diaryl alkynes as an alternative method to prepare 2,3-diaryl-substituted N-unprotected indoles with two different aryl groups. One of the aryl substituents is derived from NC-aryl ring of the nitrone and the other from the alkyne substrate, thus providing the indole products with exclusive regioselectivity. [ABSTRACT FROM AUTHOR]

4-(4-(Nitromethyl)benzylthio)pyridine (abbreviated as L), a ligand bearing 4-pyridyl and nitrobenzene groups, functions as a monodentate ligand and reacts with cobalt(II) chloride and silver(I) perchlorate, leading to new complexes [Co(L)]Cl ( 1) and [Ag(L)]ClO ( 2), respectively. Ligand L and complexes 1 and 2 were characterized through X-ray diffraction, IR spectroscopy and elemental analyses. The coordination geometry of Co(II) and Ag(I) exhibit a slightly-distorted tetrahedron and trigonal planar geometry, respectively. The structures of Ligand L [Monoclinic, P2/c, a = 7.8041(3) Å, b = 20.7401(8) Å, c = 7.2625(3) Å, α = 90°, β = 97.946(3)°, γ = 90°], Complex 1 [Triclinic, P-1, a = 16.2634(14) Å, b = 12.4102(5) Å, c = 13.6324(7) Å, α = 102.733(3)°, β = 95.632(3)°, γ = 99.480(3)°], and Complex 2 [Monoclinic, P2/c, a = 7.6144(6) Å, b = 12.8989(12) Å, c = 28.052(2) Å, α = 90°, β = 92.308(4)°, γ = 90°] reveal several different types of intermolecular interactions, such as Ag···O, π-stacking interactions, and C-H···X (X=O, S, halogen) interactions. Graphical Abstract: Mononuclear complexes [Co(L)]Cl and [Ag(L)]ClO were readily obtained and characterized [L = multidentate 4-(4-(nitromethyl)benzylthio)pyridine], the ligand behavior and the supramolecular architectures of which are observed and discussed. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

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The article discusses the crystal structure of the title compound bis(di(pyrazin-2-yl)sulfane-ĸN)tetrakis(μ2-acetato-ĸ2O:O'dicopper(II) (C12H12CuN4O4S). Topics discussed include the synthesis of the title compound, experimental data, and refinement. Also provided are the supplementary materials which include fractional atomic coordinates, atomic displacement parameters, and geometric parameters.

from 2-aminopyridines, nitroalkanes, and aldehydes [ABSTRACT FROM AUTHOR]

C13H10AgBF4N2O3, orthorhombic, Pbca (no. 61), a = 13.2751(5) Å, b = 14.6212(5) Å, c = 15.5573(6) Å, V = 3019.6 Å3, Z = 8, Rgt(F) = 0.0498, wRref(F2) = 0.1423, T = 296 K. [ABSTRACT FROM AUTHOR]