Chiral Aryliodine-Catalyzed Asymmetric Oxidative C–N Bond Formation via Desymmetrization Strategy

An asymmetric oxidative C–N bond-forming reaction is developed using a chiral diiodospirobiindane derivative as the catalyst and <i>m</i>CPBA as a terminal oxidant. The protocol is based on an asymmetric desymmetrization strategy and affords lactams or spirolactams according to the different substituents on the substrates. The products are obtained in good yields and moderate to high enantioselectivities

Asymmetric Synthesis of (−)-Pterocarine and (−)-Galeon via Chiral Phase Transfer-Catalyzed Atropselective Formation of Diarylether Cyclophane Skeleton

Pterocarine and galeon are typical examples of diarylether heptanoids (DAEHs) with planar chirality due to the strictly constrained conformations in their molecular skeletons. The characterized oxa­[1,7]­meta­para-cyclo­phane motifs in DAEHs impose great challenges for their enantioselective synthesis. The asymmetric syntheses of (−)-pterocarine and (−)-galeon are demonstrated by employing a chiral phase transfer-catalyzed highly enantioselective S_NAr cyclization as the key step for the formation of a diarylether cyclophane skeleton

Asymmetric Synthesis of (−)-Pterocarine and (−)-Galeon via Chiral Phase Transfer-Catalyzed Atropselective Formation of Diarylether Cyclophane Skeleton

Pterocarine and galeon are typical examples of diarylether heptanoids (DAEHs) with planar chirality due to the strictly constrained conformations in their molecular skeletons. The characterized oxa­[1,7]­meta­para-cyclo­phane motifs in DAEHs impose great challenges for their enantioselective synthesis. The asymmetric syntheses of (−)-pterocarine and (−)-galeon are demonstrated by employing a chiral phase transfer-catalyzed highly enantioselective S_NAr cyclization as the key step for the formation of a diarylether cyclophane skeleton

Investigation of the induction time of low-rank coal particles on rising bubble surfaces

<p>In this paper, the back-calculated induction times of low-rank coal particles on the rising bubble with mobile surfaces were back-calculated from the micro-flotation rate constants. The back-calculated induction times slightly increased with the flotation recovery increase or the surfactant concentration decrease. It is because the drainage time accounting for most of the induction time is affected by the force exerted on the wetting film. Moreover, the force exerted on the wetting film is characterized by the Reynolds number. Furthermore, the Reynolds number increased with increasing bubble rising velocity due to an increase in bubble size as a result of decreasing surfactant concentration. Therefore, the back-calculated induction times could reflect the difference in the flotation recoveries at the same surfactant concentration. Meanwhile, it indicated that the hydrodynamic condition in the flotation process had a significant effect on the back-calculated results of induction times. From this investigation, it can be speculated that the back-calculated induction time of particles sliding on the rising bubble with mobile bubble surfaces is greatly influenced by the Reynolds number.</p

Algae Polar Lipids Characterized by Online Liquid Chromatography Coupled with Hybrid Linear Quadrupole Ion Trap/Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

We report the first application of online LC-MS (liquid chromatography–mass spectrometry) characterization of algae polar lipids by nanoscale high-performance liquid chromatography followed by electrospray ionization and mass analysis with a linear ion trap (LTQ) coupled with 14.5 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Ultrahigh FT-ICR mass resolution provides highly accurate mass measurement and resolves monoisotopic peaks from interfering components for unique determination of lipid elemental compositions. We establish the polar lipid profile of fatty acids, glycolipids, phospholipids, and betaine lipids for a green algae, <i>Nannochloropsis oculata</i>, which is highly prized for its oils suitable for biodiesel production. Lipid headgroup and fatty acid identification is based on accurate mass measured by the FT-ICR MS and collision-induced dissociation (CID) MS/MS in the LTQ. Unequivocal lipid composition is further confirmed from isotopic fine structure at baseline resolutionachievable only with ultrahigh resolution FT-ICR MS

Molecular Features Influencing the Release of Peptides from Amphiphilic Polymeric Reverse Micelles

Efficient and controlled release of peptides bound to polymeric reverse micelle assemblies can be achieved through the cooperative effects of disassembly and disruption of charge–charge interactions. Through the examination of various peptides and polymer architectures, we have identified the factors that affect the release efficiency of the electrostatically bound peptides. Peptide guests and polymers with a greater number of complementary charges result in less efficient release than peptides and polymers with lower numbers of charges. Interestingly, we find that the presence of adjacent charged groups on the monomeric unit of the polymer exhibits exceptionally low release efficiency, perhaps because of a chelate-like effect, even when the total polymer charge is lower. Overall, our findings inform the design principles for catch-and-release systems based on polymeric reverse micelles, which offer great versatility and tunability

Three New Mixed-Alkali- and Alkaline-Earth-Metal Borates: From 1D Chain to 2D Layer to 3D Framework

Three new mixed-metal borates, K₄Ba₂[B₁₄O₂₀(OH)₁₀]·3H₂O (<b>1</b>), LiSr₂[B₁₀O₁₆(OH)₃] (<b>2</b>), and LiBa­[B₉O₁₅] (<b>3</b>), have been made under hydro­(solvo)­thermal conditions and characterized by means of IR, UV–vis–near-IR, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction, respectively. <b>1</b> is a 1D chain constructed from B₁₄O₂₁(OH)₁₀^10– cluster units, <b>2</b> is of a 2D layer with nine-membered-ring windows built up of B₁₀O₁₉(OH)₃^9– cluster units, while <b>3</b> exhibits a 3D framework with 12-membered-ring channels composed of B₃O₇ cluster units

Triterpenes from the fruit of <i>Camptotheca acuminata</i> suppress human hepatocellular carcinoma cell proliferation through apoptosis induction

<p>The fruit of <i>Camptotheca acuminata</i>, a kind of mainly medicinal plant, possesses good antitumor properties. In order to explore the bioactive compounds for the treatment of hepatocellular carcinoma, the study focused on the isolation of cytotoxic compounds from the fruit of <i>Camptotheca acuminata</i>, which led to the discovery of fourteen compounds, including one new triterpene, 3<i>β</i>,20-dihydroxy-30<i>α</i>-methyl,17(29)-<i>β</i>-epoxy-28-norlupane (<b>1</b>), together with thirteen known compounds (<b>2</b>–<b>14</b>). The structures of isolated compounds were demonstrated by spectroscopic methods including 1D and 2D NMR spectroscopy. Moreover, all triterpenes were evaluated for antiproliferative activities against two human hepatocellular carcinoma cell lines, HepG2 and Hep3B. Compound <b>3</b> showed the strongest cytotoxic activity against the HepG2 with IC₅₀ value at 29.6 μM. Further study demonstrated that compound <b>3</b> exhibited cytotoxic activity through the induction of apoptosis.</p

Template-Free Synthesis of Hollow-Structured Co₃O₄ Nanoparticles as High-Performance Anodes for Lithium-Ion Batteries

We have developed a template-free procedure to synthesize Co₃O₄ hollow-structured nanoparticles on a Vulcan XC-72 carbon support. The material was synthesized <i>via</i> an impregnation–reduction method followed by air oxidation. In contrast to spherical particles, the hollow-structured Co₃O₄ nanoparticles exhibited excellent lithium storage capacity, rate capability, and cycling stability when used as the anode material in lithium-ion batteries. Electrochemical testing showed that the hollow-structured Co₃O₄ particles delivered a stable reversible capacity of about 880 mAh/g (near the theoretical capacity of 890 mAh/g) at a current density of 50 mA/g after 50 cycles. The superior electrochemical performance is attributed to its unique hollow structure, which combines nano- and microscale properties that facilitate electron transfer and enhance structural robustness

Three New Mixed-Alkali- and Alkaline-Earth-Metal Borates: From 1D Chain to 2D Layer to 3D Framework

Three new mixed-metal borates, K₄Ba₂[B₁₄O₂₀(OH)₁₀]·3H₂O (<b>1</b>), LiSr₂[B₁₀O₁₆(OH)₃] (<b>2</b>), and LiBa­[B₉O₁₅] (<b>3</b>), have been made under hydro­(solvo)­thermal conditions and characterized by means of IR, UV–vis–near-IR, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction, respectively. <b>1</b> is a 1D chain constructed from B₁₄O₂₁(OH)₁₀^10– cluster units, <b>2</b> is of a 2D layer with nine-membered-ring windows built up of B₁₀O₁₉(OH)₃^9– cluster units, while <b>3</b> exhibits a 3D framework with 12-membered-ring channels composed of B₃O₇ cluster units