Reactions of d0 group 4 amides with dioxygen. Preparation of unusual oxo aminoxy complexes and theoretical studies of their formation

Reactions of d0 amides M(NMe2)4 (M = Zr, 1; Hf, 2) with O2 have been found to yield unusual trinuclear oxo aminoxide complexes M3(NMe2)6(mu-NMe2)3(mu3-O)(mu3-ONMe2) (M = Zr, 3; Hf, 4) in high yields. Tetramethylhydrazine Me2N-NMe2 was also observed in the reaction mixtures. Crystal structures of 3 and 4 have been determined. Density functional theory calculations have been performed to explore the mechanistic pathways in the reactions of model complexes Zr(NR2)4 (R = H, 5; Me, 1) and [Zr(NR2)4]2 (R = H, 5a; Me, 1a) with triplet O2. Monomeric and dimeric reaction pathways in the formation of the Zr complex 3 are proposed.     

中空纤维脂质体微筛选及其用于中药中香豆素类和木脂素类可透膜成分群的筛选和捕获

建立了中空纤维脂质体微筛选(Hollow fiber liposome microscreening,HFLMS)研究中药透膜化合物的方法。以中空纤维为脂质体载体,在模拟人体自然吸收的条件下,对中药提取液中可透膜化合物进行了筛选,并用HPLC进行分析。本研究在对空白和脂质体中空纤维表面性质表征的基础上,对中空纤维活性中心与目标物的非特异性结合和HFLMS方法的重现性进行了考察;将HFLMS与HPLC结合,分别对中药材蛇床子、补骨脂、羌活、独活提取液中透过脂质体的香豆素类成分群和五味子提取液中透过脂质体的木脂素类成分群进行了筛选和捕获;通过与对照品的色谱保留时间比对,对筛选出的与脂质体结合的部分化合物进行了结构鉴别。     

溶胶凝胶法合成LiCuVO4及其电化学性能研究

以CH3COOLi.2H2O、Cu(NO3)2.3H2O、V2O5和双氧水(30%)为原料,采用溶胶凝胶法合成了LiCuVO4,其结构、组成和形貌经XRD和SEM确认。结果表明,本文所合成的LiCuVO4具有隧道结构的形貌,颗粒粒径为0.2～6μm。将LiCuVO4作为锂离子电池正极材料,首次循环的放电比容量达到160mAh/g;而作为负极材料,其最大放电比容量达到481mAh/g。在两种电化学测试中,LiCuVO4都显示了良好的循环性能。     

β‐Diketiminatoytterbium aryloxides: synthesis,structural characterization,and catalytic activity for addition of amines to carbodiimides

The steric effect of an aryloxido group on the synthesis and molecular structures of ytterbium aryloxides supported by β‐diketiminato ligand L (L = [N(2,6‐Me₂C₆H₃)C(Me)]₂CH^?) is reported. Reactions of β‐diketiminatoytterbium dichloride, LYbCl₂(THF)₂, with NaOAr¹ in THF (Ar¹ = [2,6‐^tBu₂‐4‐MeC₆H₂], THF = tetrahydrofuran) at 60°C gave the corresponding ytterbium complexes LYb(OAr¹)Cl(THF) ( 1 ) and LYb(OAr¹)₂ (1), depending on the molar ratio of dichloride to sodium aryloxide, respectively, while the same reactions with NaOAr² and NaOAr³ (Ar² = [2,6‐ⁱPr₂C₆H₃], Ar³ = [2,6‐Me₂C₆H₃]) in 1:1 or 1:2 molar ratio in THF afforded only bisaryloxide complexes LYb(OAr²)₂(THF) (1) and LYb(OAr³)₂(THF) ( 4 ) in good yields, respectively. Complexes 1 , 2 , 3 , 4 were fully characterized, including X‐ray crystal structure analyses. All the complexes are efficient pre‐catalysts for the catalytic addition of amines to carbodiimides giving guanidines. Copyright © 2013 John Wiley & Sons, Ltd.     

Identification of metabolites in WZS‐miniature pig urine after oral administration of Danshen decoction by HPLC coupled with diode array detection with electrospray ionization tandem ion trap and time‐of‐flight mass spectrometry

Danshen (DS) is a widely used traditional Chinese medicine for treating cardiovascular and cerebrovascular diseases. A simple, rapid and sensitive method was developed for identification of the in vivo metabolites in urine of WZS‐miniature pigs after oral administration of DS decoction by HPLC coupled with diode array detection with electrospray ionization tandem ion trap and time‐of‐flight mass spectrometry. This method has been successfully applied to simultaneous identification of 50 compounds (including 11 new ones) in pig urine. In addition, one new compound, (3‐hydroxyphenyl) crylic acid glycine methyl ester (C1), along with eight known ones were first isolated by column chromatography and identified by spectroscopic means, including 1D/2DNMR and mass spectrometry, as reference substances. Ten phenolic compounds (protocatechuic aldehyde, protocatechuic acid, caffeic acid, danshensu, ferulic acid, isoferulic acid, rosmarinic acid and salvianolic acid A/B/D) were found to be the main absorbed original constituents of DS decoction, which underwent the metabolic reactions of glucuronidation, sulfation, methylation, hydrogenation and glycine conjugation in vivo. In conclusion, the developed method is applicable to the analysis and identification of constituents in biological matrices after administration of DS decoction. Copyright © 2012 John Wiley & Sons, Ltd.     

Multiple Regulation Effects of Ammonium Acetate on ZnO Growth Process in Chemical Bath Deposition

Chemical bath deposition method has been used to synthesize a variety of ZnO morphology structures. However, the specificity and interaction of acetate and ammonium ions with ZnO crystal during the growth process remain elusive. This study contributes to understand the roles of ammonium acetate on the growth mechanism of ZnO in Zn(NO₃)₂-HMTA system. The growth process indicates that the nucleation experienced Zn²⁺-layered basic zinc salts (LBZs)-ZnO process, while the self-assembled unit changed from urchin-shaped, rod-shaped to a fully coupled twin-shaped structure with increasing ammonium acetate concentration. Ammonium acetate dominates the growth process by combing the ligand-ligand interaction of acetate ions binding to the same Zn-rich (0001) polar surface and ammonium ions regulating hexamethylenetetramine (HMTA) hydrolysis. Relatively regular hexagonal wurtzite structure and a dissolve-renucleation-regrowth process which retains the twin-shaped template and renucleates at the same position are observed at ∼10 mM ammonium acetate. Photoelectrochemistry (PEC) measurements show that the uniform hexagonal ZnO rods (Y-10, the sample named as Y-x (x represents x mM ammonium acetate, herein, x is 10 mM)) have a maximum photocurrent density of 1.54 mA cm⁻² at 1.23 V (vs. RHE), much higher than that of the dumbbell-shaped ZnO rods (Y-50, 0.20 mA cm⁻²) at the same voltage. These results provide a further explanation of morphology regulation mechanisms on ZnO synthesis processes and pave the road for more practical applications.