X-ray diffraction and Raman spectra of merrillite at high pressures

ABSTRACT

The compressibility and effect of pressure on the vibrations of merrillite, Ca₉NaMg(PO₄)₇, were studied by using diamond anvil cell at room temperature combined with in-situ synchrotron X-ray diffraction and Raman spectroscopy up to about 18 and 15?GPa, respectively. The pressure-volume data was fitted by a third-order Birch–Murnaghan equation of state to determine the isothermal bulk modulus as K₀ ?=?87.2(32) GPa with pressure derivative K₀′?=?3.2(4). If K₀′?=?4, the isothermal bulk modulus was obtained as 81.6(10) GPa. The axial compressibility was estimated and an axial elastic anisotropy exists since a-axis is less compressible than the c-axis. The Raman frequencies of all observed modes for merrillite continuously increase with pressure, and the pressure dependences of stretching modes (v ₃ and v ₁) are larger than those of the bending modes (v ₄ and v ₂) and external modes. The isothermal mode Grüneisen parameters and intrinsic anharmonicity of merrillite were also calculated.     

Predicting polycyclic aromatic hydrocarbon formation with an automatically generated mechanism for acetylene pyrolysis

Using Reaction Mechanism Generator (RMG), we have automatically constructed a detailed mechanism for acetylene pyrolysis, which predicts formation of polycyclic aromatic hydrocarbons (PAHs) up to pyrene. To improve the data available for formation pathways from naphthalene to pyrene, new high‐pressure limit reaction rate coefficients and species thermochemistry were calculated using a combination of electronic structure data from the literature and new quantum calculations. Pressure‐dependent kinetics for the CH potential energy surface calculated by Zádor et al. were incorporated to ensure accurate pathways for acetylene initiation reactions. After adding these new data into the RMG database, a pressure‐dependent mechanism was generated in a single RMG simulation which captures chemistry from C to C. In general, the RMG‐generated model accurately predicts major species profiles in comparison to plug‐flow reactor data from the literature. The primary shortcoming of the model is that formation of anthracene, phenanthrene, and pyrene are underpredicted, and PAHs beyond pyrene are not captured. Reaction path analysis was performed for the RMG model to identify key pathways. Notable conclusions include the importance of accounting for the acetone impurity in acetylene in accurately predicting formation of odd‐carbon species, the remarkably low contribution of acetylene dimerization to vinylacetylene or diacetylene, and the dominance of the hydrogen abstraction CH addition (HACA) mechanism in the formation pathways to all PAH species in the model. This work demonstrates the improved ability of RMG to model PAH formation, while highlighting the need for more kinetics data for elementary reaction pathways to larger PAHs.     

微波辅助合成Ru(Ⅱ)配合物及其自组装多层膜

运用微波辅助合成技术制备得到对称性钌(Ⅱ)配合物,对该配合物进行了¹H NMR,ESI-MS和TG分析。该钌配合物两端对称的磷酸基团可通过共价键作用组装到纳米铟锡金属氧化物导电玻璃(Indium Tin Oxides,ITO)表面,使ITO表面呈现亲水性。利用锆离子作为桥梁成功组装了钌多层膜,并对该多层膜进行了循环伏安法(Cyclic Voltammetry,CV)及紫外-可见吸收光谱法(Ultraviolet-visible absorption spectrometry,UV-Vis)等光电化学分析,实验结果表明层层自组装过程中膜沉积均匀,在0.53V出现可逆的氧化还原峰,在300~600nm的紫外可见区域出现强且宽的吸收峰,表明该钌配合物具有优良的光电性能。     

On the Extreme Oxidation States of Iridium

It has recently been suggested that the oxidation states of Ir run from the putative ?III in the synthesized solid Na₃[Ir(CO)₃] to the well‐documented +IX in the species IrO₄⁺. Furthermore, [Ir(CO)₃]^3? was identified as an 18‐electron species. A closer DFT study now finds support for this picture: The orbitals spanned by the 6s,6p,5d orbitals of the iridium are all occupied. Although some have considerable ligand character, the deviations from 18 e leave the orbital symmetries unchanged. The isoelectronic systems from Os^?IV to Au^?I behave similarly, suggesting further possible species. To paraphrase Richard P. Feynmann “there is plenty of room at the bottom”.     

Cationic Cobalt(III)‐Catalyzed Aryl and Alkenyl CH Amidation: A Mild Protocol for the Modification of Purine Derivatives

A cationic cobalt(III)‐catalyzed direct C?H amidation of unactivated (hetero)arenes and alkenes by using 1,4,2‐dioxazol‐5‐ones as the amidating reagent has been developed. This transformation proceeds efficiently under external oxidant‐free conditions with a broad substrate scope. Moreover, 6‐arylpurine compounds, which often exhibit high potency in antimycobacterial, cytostatic, and anti‐HCV activities, can be smoothly amidated, thus offering a mild protocol for their late stage functionalization.     

病原微生物感染的蛋白质组学研究

基于质谱的蛋白质组学在近20年有巨大的发展。在其应用中,病原微生物和与感染相关的蛋白质组学具有重要科学意义,体系复杂度又相对较小,一直受到广泛关注并有较快发展。本文从感染中病原微生物和宿主的蛋白质组学两方面入手,简要综述应用蛋白质组学研究感染过程的相关工作,着重介绍该领域近几年的主要进展,并对其发展做出展望。     

Integrated One‐Flow Synthesis of Heterocyclic Thioquinazolinones through Serial Microreactions with Two Organolithium Intermediates

The synthesis of pharmaceutical compounds via short‐lived intermediates in a microreactor is attractive, because of the fast flow and high throughput. Additionally, intermediates can be utilized sequentially to efficiently build up a library in a short time. Here we present an integrated microfluidic synthesis of biologically active thioquinazolinone libraries. Generation of o‐lithiophenyl isothiocyanate and subsequent reaction with aryl isocyanate is optimized by controlling the residence time in the microreactor to 16 ms at room temperature. Various S‐benzylic thioquinazolinone derivatives are synthesized within 10 s in high yields (75–98 %) at room temperature. These three‐step reactions involve two organolithium intermediates, an isothiocyanate‐functionalized aryllithium intermediate, and a subsequent lithium thiolate intermediate. We also demonstrate the gram‐scale synthesis of a multifunctionalized thioquinazolinone in the microfluidic device with a high yield (91 %) and productivity (1.25 g in 5 min).