Boomerang‐Type Substitution Reaction: Reactivity of Fullerene Epoxides and a Halofullerenol

The C_s‐symmetric fullerene chlorohydrin C₆₀(Cl)(OH)(OOtBu)₄ reacts with 4‐dimethylaminopyridine (DMAP) and 1,4‐diazabicyclo[2.2.2]octane (DABCO) to yield two isomers with the formula C₆₀(O)(OOtBu)₄ in good yields. These isomers differ with respect to the location of the epoxy functionality. The one from DMAP is C_s symmetric, whereas that from DABCO is C₁ symmetric with the epoxy group on the central pentagon. Two different mechanisms are proposed to explain the chemoselectivity of these reactions. The reaction with DMAP involves single‐electron transfer as the key step; DMAP acts as the electron donor. A combination of an oxygen‐atom shift and S_N2′′ processes (boomerang substitution) are responsible for the formation of isomer with DACBO. Various related reactions support the proposed mechanisms. The structures of new fullerene derivatives were determined by spectroscopy, single‐crystal X‐ray analysis, and chemical correlation experiments.     

氮杂富勒烯的合成及反应研究进展

氮杂富勒烯是富勒烯家族中一类非常重要的化合物,由于其独特的结构和反应活性,近年来引起了人们的广泛关注.因此,对氮杂富勒烯的合成、反应方面的研究进行了概括和总结.氮杂富勒烯的合成主要有3种方法(Wudl,Hirsch,Gan),氮杂富勒烯的反应主要包括自由基反应和亲电芳环取代反应.     

Preparation of azafullerene derivatives from fullerene-mixed peroxides and single crystal X-ray structures of azafulleroid and azafullerene

Azafullerene was prepared by addition of hydroxylamine to a cage-opened fullerendione derivative and subsequent PCl5 induced rearrangement processes. X-ray structures were obtained for the azafullerene and its azafulleroid precursor.     

西柏三烯-4,6-二醇衍生物的合成及抗肿瘤活性

以烟草中含量丰富的大环二萜类化合物2,7,11-西柏三烯-4,6-二醇(CBT)为母体, 其C6位羟基经酯化/醚化, 合成了28个西柏三烯-4-醇-6-羧酸酯及西柏三烯-4-醇-6-烷氧类化合物. 采用核磁共振波谱(NMR)和高分辨质谱(HRMS)对目标化合物进行了结构表征, 并初步评价了其生物活性. 细胞毒活性测试结果表明, 部分化合物对肿瘤细胞的抑制作用与阳性对照顺铂相当, 其中α-2,7,11-西柏三烯-4-醇-6-O-苯乙酸酯(1i)对乳腺癌细胞株MCF-7的IC₅₀值为15.45 μmol/L, α-2,7,11-西柏三烯-4-醇-6-O-(2-氟)苯乙酸酯(1t)对肺癌细胞株SMMC-7721的IC₅₀值为11.44 μmol/L.     

Multi-interfaces investigation on the PLA composites toughened by modified MWCNTs

The effects of multiwalled carbon nanotubes (MWCNTs) modified by silane coupling agent (Trademark in china was KH570) and lactide (LA) on the properties of poly(lactic acid) (PLA) composites were investigated in this paper. The Scanning electronic microscopy (SEM) images showed that MWCNTs modified by both KH570 and LA, which constructed the MWCNTs-KH570-PLA nanocapsules, owned the best performances to toughen PLA. These nanocapsules were developed by solid multilayered interfaces and efficiently enhanced tnced the interfacial adhesion between PLA and MWCNTs. Polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis further verified that modified MWCNTs refined the PLA grain size and improved its crystallization. Moreover, observed by thermogravimetry (TG), the thermal stability of PLA was also improved. Then it could be drawn the conclusion that among these modified MWCNTs, MWCNTs-KH570-PLA nanocapsule was the best in toughening PLA, and the tensile strength of MWCNTs-KH570-PLA/PLA composite rose by 39.97% and its impact strength by 51.61%.     

High Production of β-Glucosidase by Aspergillus niger on Corncob

Using low-cost raw material is an effective approach for reducing the cost of cellulolytic enzymes. The farmland waste corncob was found in this study to be the best carbon source for the production of β-glucosidase by Aspergillus niger. The maximum yield of β-glucosidase activity was 48.7 IU ml(-1) by using 50 g?l(-1) of corncob powder as the substrate. It was found that the water-soluble components of the corncob could increase β-glucosidase production significantly only when mixed with Avicel or wheat bran. The soluble components could not enhance the biomass and β-glucosidase production when used alone. On the other hand, the water-insoluble components of the corncob still produced high level of β-glucosidase (30 IU ml(-1)) although lower than that of using whole corncob. The results suggested that the water-insoluble components of corncob were beneficial for β-glucosidase production. It was further demonstrated that the xylan in the water-insoluble parts of corncob was the important factor in producing β-glucosidase by A. niger.     

Large‐time behavior of solutions to the Rosenau equation with damped term

In this paper, we consider the initial value problem for the Rosenau equation with damped term. The decay structure of the equation is of the regularity‐loss type, which causes the difficulty in high‐frequency region. Under small assumption on the initial value, we obtain the decay estimates of global solutions for n≥1. The proof also shows that the global solutions may be approximated by the solutions to the corresponding linear problem for n≥2. We prove that the global solutions may be approximated by the superposition of nonlinear diffusion wave for n = 1. Copyright © 2016 John Wiley & Sons, Ltd.