Alkoxy substituted MeO-BIPHEP-type diphosphines ligands for asymmetric hydrogenation of aryl ketones

<正>In this paper,a series of optically active MeO-BIPHEP-type ligands,(S)-6,6′-dimethoxy-2,2'-bis(di-p-alkoxyphenylphosphine)- 1,1′-biphenyl were synthesized and used to prepare the ruthenium complex.The effects of para-substituted were observed,the results showed that the ruthenium catalysts[diphosphine RuCl_2 diamine]containing both t-Bu and i-Pr substitutions have better activities and enantioselectivities than the non-substituted ruthenium catalysts in the asymmetric hydrogenation of acetophenone.     

CO电子基态P线系跃迁谱线的理论研究

基于微分的思想,结合经典的双原子分子跃迁谱线表达式,提出了预言双原子分子P线系高激发振-转跃迁谱线的新解析物理公式.对于某分子电子体系的某一P支跃迁带,利用实验上获得的一组(15条)精确的跃迁谱线和该跃迁带对应的上下振动态的转动常数(B_υ',B_υ″)的精确数据,该公式不仅可以精确地重复已知的实验跃迁谱线,而且还能预测出实验上难以获得的更高激发态的跃迁谱线数据.利用该公式,研究了CO分子电子基态的(2,0)振-转跃迁带的< 关键词： 双原子分子 发射光谱 P线系')" href="#">P线系 CO     

陶瓷微滤膜在液相领域的分离机理和控制分析

介绍了陶瓷微滤膜的过滤机理,分析了膜污染的现状及其影响陶瓷微滤膜膜通量的因素,总结了陶瓷微滤膜的应用前景和亟待解决的问题.     

Synthesis and antifungal activity of chalcone derivatives

In the present study, using chalcone as a lead compound, a series of its derivatives (compounds 1–30) were designed and synthesised. Their activity of anti-pathogenic fungi of plants has been evaluated. It is found that these compounds have good antifungal activity against Sclerotinia sclerotiorum, Helminthosprium maydis, Botrytis cinerea, Rhizoctonia solani and Gibberella zeae. Among them, the inhibition of growth for compound 30 against S. sclerotiorum showed 89.9%, with the median effective concentrations (EC₅₀) of 15.4 μg mL^? 1. The inhibition of growth for compounds 28, 29 and 30 at a concentration of 100 μg mL^? 1 against H. maydis is 90.3%, 90.7% and 91.1%, with EC₅₀ of 15.1, 18.3 and 18.1μg mL^? 1, respectively.     

Preparation and characterization of modified graphite oxide/poly(propylene carbonate) composites by solution intercalation

Modified graphite oxide (MGO)/Poly (propylene carbonate) (PPC) composites with excellent thermal and mechanical properties have been prepared via a facile solution intercalation method. An intercalated structure of MGO/PPC composites was confirmed by X-ray diffraction and scanning electron microscope. The thermal and mechanical properties of MGO/PPC composites were investigated by thermal gravimetric analysis, differential scanning calorimetric, dynamic mechanical analysis, and electronic tensile tester. Due to the nanometer-sized dispersion of layered graphite in PPC matrix and the strong interfacial interaction between MGO and PPC, the prepared MGO/PPC composites exhibit improved thermal and mechanical properties in comparison with pure PPC. Compared with pure PPC, the MGO/PPC composites show the highest thermal stability and the T_g is 13.8 °C higher than that of pure PPC, while the tensile strength (29.51 MPa) shows about 2 times higher than that of pure PPC when only 3.0 wt.% MGO is incorporated. These results indicate that this approach is an efficient method to improve the properties of PPC.     

Synthesis and application of chiral N, N'-dialkylated cyclohexanedi- amine for asymmetric hydrogenation of aryl ketones

Chiral N, N'-dialkylated cyclohexanediamine derived ligands have been synthesized and used in the asymmetric hydrogenation of aryl ketones. Optically active alcohols with up to 90% enantiomeric excess were obtained in high yields.     

Largely enhanced ductility of immiscible high density polyethylene/polyamide 6 blends via nano‐bridge effect of functionalized multiwalled carbon nanotubes

Immiscible polymer blends usually exhibit negative deviation in mechanical properties compared with the corresponding pure polymers due to the weak interfacial bonding between the two polymers. Due to the bridge effect of the oriented carbon nanotubes (CNTs) on the craze and crack development at the load of stress, CNTs have been proved to be efficient toughening agent for polymers. In this work, functionalized multiwalled carbon nanotubes (FMWCNTs) have been introduced into immiscible high density polyethylene/polyamide 6 (HDPE/PA6) blends through different sample preparation methods. The mechanical measurements demonstrate that, when the nanocomposite is prepared from the HDPE master batch, the sample exhibits excellent tensile strength and toughness simultaneously. For all the nanocomposites, FMWCNTs tend to migrate and/or maintain in PA6 particles, leading to the variation of the crystallization behavior in PA6 phase. Further results based on morphologies characterization indicate that the intensified interfacial adhesion between HDPE and PA6, which is realized by the nano‐bridge effect of FMWCNTs in the interfaces, is the main reason for the largely improved ductility. Copyright © 2010 John Wiley & Sons, Ltd.     

Protective effects of baicalin and quercetin on an iron-overloaded mouse: comparison of liver, kidney and heart tissues

Excessive accumulation of iron in the body can lead to organ injury. Some flavonoids which possess high affinity to iron can be used as iron chelators for curing iron overload diseases such as haemochromatosis. In this article, the effects of baicalin and quercetin on different mouse tissues (liver, kidney and heart) afflicted with iron overload-induced injury were studied. It was found that after administration of 500 mg kg?1 iron dextran for 45 days, the degree of oxidative injury in the three organs was different. When iron dextran-induced iron-overloaded mice were fed a diet containing baicalin or quercetin (1% w/w), both flavonoids showed significant effects in suppressing iron overload-induced injury. The efficiencies of both flavonoids on different tissues varied. Both flavonoids caused a significant decrease of iron content in liver and kidney tissues but not in the heart, whereas the flavonoids were more efficient in inhibiting the increase of carbonyl content and the thiobarbituric acid reactive substance levels in heart tissues. The results indicate that the protective effects of baicalin and quercetin on different tissues of iron-overloaded mice are different.     

Isolation and identification of 2-isopropyl-5-methylphenol from Stellera chamaejasme and its insecticidal activity against Aphis craccivora and Pieris rapae

In this study, the root powder of Stellera chamaejasme was extracted with chloroform. The crude extract thus obtained was chromatographed several times with silica gel columns and finally one pure natural product was obtained. This product was identified as 2-isopropyl-5-methylphenol (thymol), which was separated for the first time from S. chamaejasme root. The results of a laboratorial bioassay showed that it had good insecticidal activity against Aphis craccivora and Pieris rapae. Its median lethal concentrations (LC50) (24 h after treatment) were 14.81 and 47.68 mg L(-1), respectively. This is the first time that the insecticidal activity of thymol against A. craccivora and P. rapae has been reported.     

Binuclear methylborole iron carbonyls: iron-iron multiple bonds and perpendicular structures

Methylborole iron tricarbonyl, (η(5)-C(4)H(4)BCH(3))Fe(CO)(3), is known experimentally and is a potential source of binuclear (C(4)H(4)BCH(3))(2)Fe(2)(CO)(n) (n = 5, 4, 3, 2, 1) derivatives through reactions such as photolysis. In this connection the lowest energy (C(4)H(4)BCH(3))(2)Fe(2)(CO)(5) structures are predicted theoretically to have a single bridging carbonyl group and Fe-Fe distances consistent with formal single bonds. The lowest energy (C(4)H(4)BCH(3))(2)Fe(2)(CO)(4) structures have two bridging carbonyl groups and Fe═Fe distances suggesting formal double bonds. Analogously, the lowest energy (C(4)H(4)BCH(3))(2)Fe(2)(CO)(3) structures have three bridging carbonyl groups and very short Fe≡Fe distances suggesting formal triple bonds. The tetracarbonyl (C(4)H(4)BCH(3))(2)Fe(2)(CO)(4) is predicted to be thermodynamically unstable toward disproportionation into (C(4)H(4)BCH(3))(2)Fe(2)(CO)(5) + (C(4)H(4)BCH(3))(2)Fe(2)(CO)(3), whereas the tricarbonyl is thermodynamically viable toward analogous disproportionation. The lowest energy structures of the more highly unsaturated methylborole iron carbonyls (C(4)H(4)BCH(3))(2)Fe(2)(CO)(n) (n = 2, 1) have hydrogen atoms bridging an iron-carbon bond. In addition, the lowest energy (C(4)H(4)BCH(3))(2)Fe(2)(CO) structures are "slipped perpendicular" structures with bridging methylborole ligands, a terminal carbonyl group, and agostic CH(3)→Fe interactions involving the methyl hydrogens. Thus, in these highly unsaturated systems the methyl substituent in the methylborole ligand chosen in this work is not an "innocent bystander" but instead participates in the metal-ligand bonding.