Ruthenium(II)-Catalyzed Asymmetric Inert C−H Bond Activation Assisted by a Chiral Transient Directing Group

A ruthenium(II)-catalyzed asymmetric intramolecular hydroarylation assisted by a chiral transient directing group has been developed. A series of 2,3-dihydrobenzofurans bearing chiral all-carbon quaternary stereocenters have been prepared in remarkably high yields (up to 98 %) and enantioselectivities (up to >99 % ee). By this methodology, a novel asymmetric total synthesis of CB2 receptor agonist MDA7 has been successfully developed.     

MnOx/Al2O3/Ce0.45Zr0.45M0.10Oy （M = Mn, Y, La） catalysts used for ethanol catalytic combustion

MnOx/Al2O3/Ce0.45Zr0.45M0.10Oy (M = Mn,Y,La) catalysts were prepared by impregnation method and characterized by BET,TPR and XRD analyses.The catalytic activities toward ethanol combustion were investigated in a microreactor.The results demonstrated that the catalytic activity of MnOx/Al2O3/Ce0.50Zr0.50O2 monolithic catalyst could be improved by doping Mn,Y and La into Ce0.50Zr0.50O2.When doping Y into Ce0.50Zr0.50O2,the catalyst MnOx/Al2O3/Ce0.45Zr0.45Y0.10O1.95 showed the highest activity.The 100% conversion temperature of ethanol was 230 ℃.Furthermore,once the conversion of ethanol started,the complete conversion was quickly achieved.The doping of Mn,Y and La led to better activity for ethanol combustion and lower temperature reduction peaks in TPR profiles.The doping of Mn resulted in enhanced oxygen storage capacity (OSC),larger area of the reduction peaks,and excellent reactivity,and the doping of Y resulted in the lowest reduction temperature and the best activity.     

短腔Er/Yb光纤光栅激光器

报道采用光敏Ｅｒ／Ｙｂ 光纤制作短腔Ｅｒ／Ｙｂ 光纤光栅激光器的实验结果。激光谐振腔由一对直接写在３０ ｍ ｍ 长的Ｅｒ／Ｙｂ 光纤上、长度分别为６ ｍ ｍ 及１０ ｍ ｍ 、反射率分别为９０％ 及９８．６％ 、３ ｄＢ带宽分别为０．２８ ｎｍ 及０．２６ ｎｍ 的光纤布拉格光栅组成, 激光器的泵浦阈值为８ｍ Ｗ, 斜效率约１４％ , 输出光的信噪比为６１ ｄＢ, 偏振模抑制比为３０ ｄＢ。     

Stimuli‐responsive chiral polyacetylene based on copolymerization of N‐propargylamide and propargylether

Copolymerization of propargylether having antipyrine group (PT) and N‐(tert‐butoxycarbonyl)‐l ‐valine‐N‐propargylamide (LA) was conducted with (nbd)Rh⁺[η⁶‐C₆H₅B^?(C₆H₅)₃] as a catalyst to obtain novel antipyrine‐functionalized chiral copolymer. The controllable secondary structure of the copolymers by different unit ratio or solvent environment led to a controlled fluorescence of the side‐chain antipyrine. Poly(LA₈₈‐co‐PT₁₂) exhibited a large specific rotation and a circular dichroism (CD) signal, while it emitted very stronger fluorescence. From CD and ultraviolet–visible spectra, the regular structure of poly(LA₈₈‐co‐PT₁₂) was destroyed, and the random coil was formed with temperature increase. The helical conformation of poly(LA₇₅‐co‐PT₂₅) disappeared by the addition of MeOH to CHCl₃ solution, while the fluorescence signal also became weaker than in CHCl₃ solution. It is suggested that the copolymer conformation much influenced the performance of chromophores. In the present study, the helix conformation could induce fluorescence enhancement. Copyright © 2015 John Wiley & Sons, Ltd.     

A study of design approach of spreading schemes for viral marketing based on human dynamics

Before launching a real viral marketing campaign, it is needed to design a spreading scheme by simulations. Based on a categorization of spreading patterns in real world and models, we point out that the existing research (especially Yang et al. (2010) Ref.  [16]) implicitly assume that if a user decides to post a received message (is activated), he/she will take the reposting action promptly (Prompt Action After Activation, or PAAA). After a careful analysis on a real dataset however, it is found that the observed time differences between action and activation exhibit a heavy-tailed distribution. A simulation model for heavy-tailed pattern is then proposed and performed. Similarities and differences of spreading processes between the heavy-tailed and PAAA patterns are analyzed. Consequently, a more practical design approach of spreading scheme for viral marketing on QQ platform is proposed. The design approach can be extended and applied to the contexts of non-heavy-tailed pattern, and viral marketing on other instant messaging platforms.     

Ruthenium(II)‐Catalyzed Asymmetric Inert C−H Bond Activation Assisted by a Chiral Transient Directing Group

A ruthenium(II)‐catalyzed asymmetric intramolecular hydroarylation assisted by a chiral transient directing group has been developed. A series of 2,3‐dihydrobenzofurans bearing chiral all‐carbon quaternary stereocenters have been prepared in remarkably high yields (up to 98 %) and enantioselectivities (up to >99 % ee). By this methodology, a novel asymmetric total synthesis of CB2 receptor agonist MDA7 has been successfully developed.     

Development of an LC–MS/MS method for quantifying two main metabolites of abivertinib in human plasma

Abivertinib represents a highly selective irreversible epidermal growth factor receptor tyrosine kinase inhibitor. Two major metabolites of abivertinib, M7 and MII-6, were detected in human plasma, which are recommended to be monitored for safety reasons in clinical trial. A high-throughput quantification method utilizing liquid chromatography–tandem mass spectrometry was designed and verified to quantify abivertinib's primary metabolites in human plasma. Solid-phase extraction was used to process the plasma, and then the analytes underwent a gradient elution separation in an Aquity UPLC BEH C₁₈ column (1.7 μm, 2.1 × 50 mm) with mobile phase A (10 mm ammonium acetate containing 0.1% formic acid) and mobile phase B (methanol–acetonitrile, 2:8, v/v, with 0.1% formic acid). Ion transitions of M7 (m/z 490.2 → 405.1) and MII-6 (m/z 476.2 → 391.1) were monitored under multiple reaction monitoring mode and electrospray ionization in positive ion mode. This simultaneous determination method was found to have acceptable precision, accuracy and linearity in the 0.5–500 ng/mL range for M7 and the 0.5–500 ng/mL range for MII-6, accompanied by a mild matrix effect but high recovery. Further stability assessments indicated that both analytes remained stable throughout the entire experimental process from harvesting whole blood to plasma extraction and analysis.     

Enantioselective Synthesis of C−N Axially Chiral N‐Aryloxindoles by Asymmetric Rhodium‐Catalyzed Dual C−H Activation

The first enantioselective Satoh–Miura‐type reaction is reported. A variety of C?N axially chiral N‐aryloxindoles have been enantioselectively synthesized by an asymmetric rhodium‐catalyzed dual C?H activation reaction of N‐aryloxindoles and alkynes. High yields and enantioselectivities were obtained (up to 99 % yield and up to 99 % ee). To date, it is also the first example of the asymmetric synthesis of C?N axially chiral compounds by such a C?H activation strategy.     

Field effect and charge injection in hybrid nanorod heterostructure

Recent studies on organic/inorganic heterostructures have indicated that interface morphology plays an important role in determining the charge transport properties. Hybrid heterostructure light-emitting diodes mixing donor and acceptor semiconductors appear to offer the best opportunity in achieving superior performance and there are indications that a network of percolated heterojunctions can be very effective in promoting light absorption/emission. Charge transport however can be more complex in a nanorod heterostructure as the charge flow at the interface will depend on the injection mechanism(s) as well as the interface field strength. In this work, we examined the current density–voltage characteristics of the hybrid NPB (N, N′-di(napth-2-yl)-N-N′-diphenylbenzidine)–ZnO nanorod heterostructure and attempted to identify the transport mechanism(s) close to the tips of the nanorods. Our study indicated that charge flow essentially followed the conventional pattern changing from a linear regime (emission-limited) to a quadratic regime (space-charge limited) and possibly to a rapid rise in current (trap-free injection). Detailed evaluation of the changes in the reported conductivity data further suggested the conduction mechanism (up to a p-layer thickness of 400 nm) was dominated by space-charge limited current in the NPB layer, which also resulted in substantial charge pile-up near the tips of the nanorods. An interface charge layer responsible for the barrier height modification effect could be used to explain the observed “blue-shift” in the emission spectra of the nanorod heterostructure light-emitting diode as reported by Sun et al. [2].