Enantiomorphs of a carbene–ruthenium(II)–porphyrin complex with four `chiral pillars'

The chiral metalloporphyrin (dibenzoylmethylene‐κC)(ethanol‐κO){5,10,15,20‐tetrakis[(1S,4R,5R,8S)‐1,2,3,4,5,6,7,8‐octahydro‐1,4:5,8‐dimethanoanthracen‐9‐yl]porphyrinato‐κ⁴N}ruthenium(II)–ethanol–dichloromethane (1/2/2), [Ru(C₈₄H₇₆N₄)(C₁₅H₁₀O₂)(C₂H₆O)]·2C₂H₆O·2CH₂Cl₂, and its enantiomorph were prepared from enantiomerically pure porphyrins. The enantiomers are potential versatile catalysts for asymmetric cyclopropanation, aziridination or epoxidation. In each compound, the rather large dibenzoylcarbene group is squeezed between four columnar 1,2,3,4,5,6,7,8‐octahydro‐1,4:5,8‐dimethanoanthracen‐9‐yl groups at the meso positions resulting in a doming deformation of the porphyrin core. The dibenzoylcarbene group has an anti conformation. The benzoyl O atoms make short van der Waals contacts (< 2.6 Å) with the methine groups of the chiral columnar substituents at the 10 and 20 positions of the porphyrin rings. A hydrogen‐bonded supramolecular chain is formed parallel to the b axis by interactions between the benzoyl O atom and the hydroxy groups of the coordinated and uncoordinated ethanol molecules.     

Label-free electronic detection of DNA-hybridization on nanogapped gold particle film

A label-free high-resolution DNA sensing technique using a nanogapped gold particle film is presented to acquire nucleotide polymorphism information, which can be read by electronic protocols.     

Emergence of a multidomain regime and spatiotemporal chaos in Gunn diodes under impact ionization conditions

Nonlinear spatiotemporal dynamics of carrier densities in Gunn diodes under impact ionization conditions is numerically investigated using a set of model partial differential equations. Numerical results show that a multidomain regime emerges as a result of the decrease in domain size caused by impact ionization, and that the spatiotemporal evolution of the domains becomes chaotic in the presence of strong impact ionization.     

Molecular Weight Distribution of Living Radical Polymers

Summary: The molecular weight distribution formed in an ideal living radical polymerization is considered theoretically. It was found that the hypergeometric function that combines the most probable and the Poisson distribution represents a fundamental distribution of the living radical polymers. The number‐ and weight‐average molecular weights are derived for this fundamental distribution, together with those for polymerizations in a batch and in a continuous stirred tank reactor. These average molecular weight functions are obtained based on the arithmetic calculations without deriving the distribution functions. The effect of the monomer transfer reactions on the formed MWD is also considered. The present study clarifies the relationship between the reaction mechanism and the formed molecular weight distribution as well as the fundamental characteristics of living radical polymers.

Calculated number fraction distribution N(r) development with (dashed) and without (solid) the monomer transfer reactions.     

Photochromism of organometallic compounds with structural rearrangement

This article introduces photochromic properties together with structures of organometallic compounds that undergo photo-induced structural rearrangement. The aim of this review is to survey the research on photochromism by using organometallics which possess by their own nature the properties responsible for the photochromism such as bonding and structural fluxionality, electronic state fluctuation, and photochemically active characteristic in both solution and the solid state. Therefore, the organometallics which include the well-characterized organic photochromic moieties, considered to be derivatives of such kinds of organic photochromic compounds, are excluded in this article. Mono-, di-, and poly-nuclear organometallic compounds are presented based on the reaction types such as linkage isomerization, haptotropic rearrangement, and reorganization of metal–ligand and/or metal–metal bonds. Very recently, the crystalline-state photochromism is becoming an attractive field of photochromic chemistry. As a demonstrative example, the photochromism of organometallic rhodium dinuclear complexes having a dithionite ligand (μ-O₂SSO₂), which shows 100% reversible interconversion in the crystalline-state and have been developed in the authors’ laboratory, will be discussed.     

不同工作介质下二氧化锰/膨胀石墨复合材料的电化学电容器行为

研究了氧化还原法制备二氧化锰/膨胀石墨复合材料用作电化学电容器, 利用热重分析、比表面及X射线衍射方法对材料的组成及结构进行了表征, 利用三电极循环伏安及充放电循环法研究了材料在硫酸钠、氯化钠、氯化钾及硝酸钾不同电解质中的电化学行为. 研究结果表明, 二氧化锰以非晶态的形式在复合材料中存在, 膨胀石墨起良好电导作用, 随其用量的增加, 复合材料的比表面下降, 但二氧化锰的比电容增加. 不同工作介质中电化学行为显示, 复合材料电化学行为的不同主要跟阳离子的种类有关. 在钠离子电解质中, 复合材料电极体现较高的表观电容和真实电容, 在钾盐电解质体系中, 复合材料电极的电流响应速度比较快, 这是由于钠盐和钾盐溶液具有不同的水合数、水合半径和电导率. 当复合材料中膨胀石墨的用量为24%左右时, 复合材料在2 mV/s扫描速度下, 在1 mol/L Na₂SO₄溶液中体现的比电容为220 F/g, 复合材料显示优良的循环性能.     

Activation and Facile Dealkylation of Monooxides of 1,8-Bis(alkylthio)naphthalene and 2,2′-Bis(alkylthio)biphenyl with Triflic Anhydride via Dithiadications

Abstract

Dithiadications bearing 1,8-bis(alkylthio)naphthalene 2A(a-e) and 2,2′-bis(alkylthio)biphenyl 2B(a-e) structure undergo either the facile deprotonation from the methyl group or dealkylation from the methylene groups by the triflate anion. Dications 2A(a) and 2B(a) having methyl groups were deprotonated readily to afford cyclic sulfonium salts 3A(a) and 3B(a). However, dithiadications 2A(b-e) and 2B(b-e) having ethyl, propyl, isopropyl and benzyl groups were readily dealkylated even at -45°C to give thiasulfonium salts 4A(b-e) and 4B(b-e) and alkyl triflates 5(a-e) in good yields. The intermediary formation of dithiadications 2A(a-e) and 2B(a-e) were confirmed by direct observation using NMR spectroscopy, D-labelled experiments and trapping experiments.     

Adhesion of a pair of polyethylene moldings by polyethylene gels

It was found that polyethylene gels in solvents such as benzene, toluene, xylene, decalin, tetralin, tetrachloroethylene, 1,1,2,2-tetrachloroethane, and chlorobenzene are effective for adhesion of a pair of polyethylene plates. In particular, the adhesion strength of polyethylene gels in decalin, tetralin and tetrachloroethylene was strong enough for practical use.Adhesive effect appears due to local dissolution of the surface of polyethylene plate in contact with the gel with increasing temperature, and subsequent recrystallization.     

Liquid chromatography-electrospray tandem mass spectrometric assay suitable for quantitation of YM155, a novel small-molecule survivin suppressant, in dog plasma

This paper describes a sensitive and selective liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for determination of the novel survivin suppressant YM155, 1-(2-methoxyethyl)-2-methyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)-4,9-dihydro-1H-naphtho[2,3-d]imidazolium, which is developed for the treatment of solid tumors. This method uses a liquid-liquid extraction from 0.25 mL of dog plasma. LC separation was carried out on a Genesis Silica column (50 mm x 3.0 mm i.d.) at a flow-rate of 0.5 mL/min. Compounds were eluted using a mobile phase of 5 mm ammonium acetate and 0.1% formic acid in water-0.1% formic acid in acetonitrile, 17:83 (v/v). MS/MS detection was carried out with an MDS-Sciex API3000 triple quadrupole mass spectrometer in positive electrospray ionization mode. The standard curve was linear from 0.05 to 50 ng/mL (r > or = 0.9968). The lower limit of quantitation was 0.05 ng/mL. Good intra- and inter-day assay precision (within 7.4% RSD) and accuracy (within +/-12.3%) were obtained. The extraction recovery was 66.2%. The method was successfully applied to preclinical pharmacokinetic studies in dogs.