A new flavonoid from Cudrania cochinchinensis

Chemical investigation of the ethanol extract of the roots of Cudrania cochinchinensis led to the isolation of a new flavonoid, (6S,12S,13R)-1-methoxy cyanomaclurin (1), together with seven known compounds, 1,3,5-trihydroxy-4-(3′-hydroxy-3′-methylbutyl)xanthone (2), 1,3,6-trihydroxy-4-prenylxanthone (3), 1,3,6,7-tetrahydroxyxanthone (4), 1,3,5,6-tetrahydroxyxanthone (5), 1,3,6-trihydroxy-5-methoxyxanthone (6), resveratrol (7) and oxyresveratrol (8). The structure of compound 1 was elucidated on the basis of 1D and 2D NMR spectra and the HR-ESI-MS data. The absolute stereochemistry was deduced via Rh₂(OCOCF₃)₄-induced CD and NOESY spectra.     

Threading Chalcogenide Layers with Polymer Chains

Inserting polymers into a crystalline inorganic matrix to understand the structure, position, and the structure–property relationships of the resulting composites is important for designing new inorganic‐organic materials and tuning their properties. Single crystals of polymer‐chalcogenide composites were successfully prepared by trapping polyethyleneglycol within a selenidostannate matrix under surfactant‐thermal conditions. This work might provide a new strategy for preparing novel crystalline polymer‐inorganic composites through encapsulating polymer chains within inorganic matrices.     

Direct Insight into the Three‐Dimensional Internal Morphology of Solid–Liquid–Vapor Interfaces at Microscale

Solid–liquid–vapor interfaces dominated by the three‐phase contact line, usually performing as the active center in reactions, are important in biological and industrial processes. In this contribution, we provide direct three‐dimensional (3D) experimental evidence for the inside morphology of interfaces with either Cassie or Wenzel states at micron level using X‐ray micro‐computed tomography, which allows us to accurately “see inside” the morphological structures and quantitatively visualize their internal 3D fine structures and phases in intact samples. Furthermore, the in‐depth measurements revealed that the liquid randomly and partly located on the top of protrusions on the natural and artificial superhydrophobic surfaces in Cassie regime, resulting from thermodynamically optimal minimization of the surface energy. These new findings are useful for the optimization of classical wetting theories and models, which should promote the surface scientific and technological developments.     

Electrodeposition and characterization of Zn–Sn alloy coatings from a deep eutectic solvent based on choline chloride for corrosion protection

With the aim of obtaining high corrosion resistant Zn–Sn alloy coatings from an ionic liquid, the effects of electrodeposition potential and electrolyte composition on the electrodeposition behavior, film composition, morphology and corrosion performance were investigated. Cyclic voltammograms indicate that Zn and Sn were co‐deposited at distinct reduction potentials as pure Zn and Sn elements. In addition, the phase composition analysis also showed that the obtained Zn–Sn alloy deposits (8 wt.%–45 wt.% Zn) consist of a two‐phase mechanical mixture of small aggregates of Zn and Sn metals. The Zn content of the alloy significantly increases as the electrodeposition potential and electrolyte Zn (II)/Sn (II) ratio increase. The corrosion performance study of the obtained Zn–Sn coatings showed that they have a passivation behavior and their corrosion resistance increases as the alloy‐Sn content increases. To improve their morphological properties, ethylene diamine tetraacetic acid additive was introduced into the electrolyte and greatly improved the morphology and corrosion resistance of the deposits. For the first time, it was shown that high corrosion resistance Zn–Sn coatings can be obtained from ionic liquids. Copyright © 2014 John Wiley & Sons, Ltd.     

The tribological performance of fullerene‐like hydrogenated carbon films under ionic liquid lubrication

Fullerene‐like hydrogenated carbon films were deposited on Si substrate by plasma‐enhanced chemical vapor deposition. The microstructures of films were characterized by high‐resolution transmission electron microscopy and Raman spectrum. The tribological performance of films was tested by reciprocating ball‐on‐disc tester under 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ionic liquid. The surface morphology and chemical composition of wear tracks and wear rates were investigated by optical microscope, X‐ray photoelectron spectroscopy, and 3D surface profiler. The results indicated that the film with a typical fullerene‐like structure embedded into the amorphous sp² and sp³ carbon networks could be prepared successfully, and the film shows a higher hardness (26.7 GPa) and elastic recovery (89.9%) compared with the amorphous carbon film. Furthermore, the film shows a lower friction coefficient at low contact load and friction frequency, and excellent wear‐resistance performance at high load and frequency under ionic liquid lubrication. Meanwhile, the wear life of fullerene‐like hydrogenated carbon films could be improved significantly using ionic liquid as a lubrication material. Copyright © 2015 John Wiley & Sons, Ltd.     

Stochastic/Controlled Symmetry Breaking of the T8‐POSS Cages toward Multifunctional Regioisomeric Nanobuilding Blocks

Precise synthesis of nanobuilding blocks with accurately positioned functional groups presents a daunting challenge. Herein, a practical synthesis and thorough characterization of a series of T₈‐polyhedral oligomeric silsesquioxane (POSS) di‐ and triadducts is reported. Upon addition of triflic acid across the double bonds in octavinylPOSS (V₈T₈) followed by hydrolysis, the cubic symmetry of the T₈‐POSS cage (O_h) is broken into C_2v (ortho‐), C_2v (meta‐), and D_3d (para‐) for diadducts and further to C_s (oom‐), C_s (omp‐), and C_3v (mmm‐) for triadducts in a stochastic fashion. Their structures and regioconfigurations have been unambiguously demonstrated by ¹H, ¹³C, and ²⁹Si NMR spectroscopy, as well as MALDI‐TOF mass spectrometry. The assignment of the diadducts was further corroborated by converting each individual diadduct into triadduct(s), the structure of which is controlled by the symmetry of the precursor. Except for the C_3v triadduct, they can all be prepared in synthetically useful quantities. The presence of two types of highly reactive and mutually orthogonal functional groups facilitates further modification into complex nanostructures and composite materials. These unique regioisomers provide a versatile platform for constructing giant molecules and Janus silsesquioxanes.     

Tuning the Redox Properties of a Nonheme Iron(III)–Peroxo Complex Binding Redox‐Inactive Zinc Ions by Water Molecules

Redox‐inactive metal ions play important roles in tuning chemical properties of metal–oxygen intermediates. Herein we report the effect of water molecules on the redox properties of a nonheme iron(III)–peroxo complex binding redox‐inactive metal ions. The coordination of two water molecules to a Zn²⁺ ion in (TMC)Fe^III‐(O₂)‐Zn(CF₃SO₃)₂ ( 1 ‐Zn²⁺) decreases the Lewis acidity of the Zn²⁺ ion, resulting in the decrease of the one‐electron oxidation and reduction potentials of 1 ‐Zn²⁺. This further changes the reactivities of 1 ‐Zn²⁺ in oxidation and reduction reactions; no reaction occurred upon addition of an oxidant (e.g., cerium(IV) ammonium nitrate (CAN)) to 1 ‐Zn²⁺, whereas 1 ‐Zn²⁺ coordinating two water molecules, (TMC)Fe^III‐(O₂)‐Zn(CF₃SO₃)₂‐(OH₂)₂ [ 1 ‐Zn²⁺‐(OH₂)₂], releases the O₂ unit in the oxidation reaction. In the reduction reactions, 1 ‐Zn²⁺ was converted to its corresponding iron(IV)–oxo species upon addition of a reductant (e.g., a ferrocene derivative), whereas such a reaction occurred at a much slower rate in the case of 1 ‐Zn²⁺‐(OH₂)₂. The present results provide the first biomimetic example showing that water molecules at the active sites of metalloenzymes may participate in tuning the redox properties of metal–oxygen intermediates.     

Catalytic Asymmetric Construction of α‐Quaternary Cyclopentanones and Its Application to the Syntheses of (−)‐1,14‐Herbertenediol and (−)‐Aphanorphine

A novel and efficient strategy to build α‐benzylic quaternary cyclopentanones with excellent enantioselectivities (up to 96 % ee) and high yields (up to 99 % yield) has been developed, and its application demonstrated by the first catalytic asymmetric total synthesis of (?)‐1,14‐herbertenediol and the formal synthesis of (?)‐aphanorphine.     

Aggregation‐Induced Emission of Hexaphenyl‐1,3‐butadiene

A new type of AIE molecules based on hexaphenyl‐1,3‐butadienes was reported with respect to the synthesis and characterization. This material exhibited different maximum emission wavelength and enhanced emission intensity at different aggregate state (amorphous and crystalline state).     

Identification,control strategies,and analytical approaches for the determination of potential genotoxic impurities in pharmaceuticals: A comprehensive review

Potential genotoxic impurities in pharmaceuticals at trace levels are of increasing concern to both pharmaceutical industries and regulatory agencies due to their possibility for human carcinogenesis. Molecular functional groups that render starting materials and synthetic intermediates as reactive building blocks for small molecules may also be responsible for their genotoxicity. Determination of these genotoxic impurities at trace levels requires highly sensitive and selective analytical methodologies, which poses tremendous challenges on analytical communities in pharmaceutical research and development. Experimental guidance for the analytical determination of some important classes of genotoxic impurities is still unavailable in the literature. Therefore, the present review explores the structural alerts of commonly encountered potential genotoxic impurities, draft guidance of various regulatory authorities in order to control the level of impurities in drug substances and to assess their toxicity. This review also describes the analytical considerations for the determination of potential genotoxic impurities at trace levels and finally few case studies are also discussed for the determination of some important classes of potential genotoxic impurities. It is the authors’ intention to provide a complete strategy that helps analytical scientists for the analysis of such potential genotoxic impurities in pharmaceuticals.