Synthesis and characterization of model 3‐miktoarm star copolymers of poly(dimethylsiloxane) and poly(2‐vinylpyridine)

3‐Miktoarm star copolymers, 3μ‐D₂V, with two poly(dimethylsiloxane) (PDMS) and one poly(2‐vinylpyridine) (P2VP) arm, were synthesized by using anionic polymerization–high vacuum techniques and (chloromethylphenylethyl)methyl dichlorosilane, heterofunctional linking agent, with two SiCl groups and one CH₂Cl group. The synthetic strategy involves the selective reaction of the two ? SiCl groups with PDMSOLi living chains, followed by reaction of the remaining chloromethyl group with P2VPLi. Combined molecular characterization results (size exclusion chromatography, membrane osmometry, and ¹H NMR spectroscopy) revealed a high degree of structural and compositional homogeneity. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 614–619, 2006     

Catalytic enantioselective Mukaiyama aldol reaction via a chiral indium(III)-pybox complex

A chiral indium(III) complex prepared from indium triflate and a pybox ligand has been developed to give good yields and enantioselectivities (up to 92% ee) in the addition of (1-methoxy-2-methyl-propenyloxy)-trimethylsilane to various aromatic and aliphatic aldehydes via the Mukaiyama aldol reaction.     

TDI三聚体的合成研究

以一种碱金属羧酸盐K-1000作为甲苯二异氰酸酯(TDI)三聚反应的催化剂合成了以TDI三聚体为主要成分的多异氰酸酯固化剂。对合成工艺条件进行了探讨。结果表明,将反应温度控制在35℃,催化剂K-1000用量为0.06%时,用苯甲酰氯作为阻聚剂可得到性能基本稳定的TDI三聚体产品。     

Chiral separations by host-guest complexation with cyclodextrin and crown ether in capillary zone electrophoresis

Summary Capillary zone electrophoresis using cyclodextrins and a chiral crown ether as buffer constituents was studied for the enantiomeric separation of drugs and amino acids. Based on results obtained from separation of racemic -amino acids both chiral selectors are compared with respect to resolution, efficiency and retention time. For (±)-Quinagolide effects of buffer composition and temperature are examined using -cyclodextrin as chiral agent. Optimum conditions were pH 2.5 at 30 mmol L^–1 -cyclodextrin. A linear dependence of retention on -cyclodextrin concentration allowed calculation of formation constants of the host-guest complexes. Buffer concentration and temperature also influence resolution. The application of a chiral crown ether to the separation of optical isomers in capillary zone electrophoresis is described for the first time. Chiral recognition of solutes depends on the formation of protonated alkyl amines and separation is attributed to the formation of diastereomeric host-guest complexes with different interactions for each enantiomer. The effects of crown ether concentration on resolution are presented.     

Effect of Oxalic Acid on Stabilization and Property of Sb-Doped Tin Oxide Sol

Zeta potential studies show that the ATO nanoparticle surface is positively charged in pH range from 2 to 5 without oxalic acid. The addition of oxalic acid brings a charge reversal on the surface of ATO particle in a wide pH range. The interaction of oxalic acid with surface of ATO nanoparticle was studied by FTIR and indicates that the most probable mechanism is the formation of Sn-O-C bonds via the condensation reaction between the oxalic acid and surface hydroxyl groups. TEM, X-ray diffraction and UV-Vis-Near IR spectra were used to characterize the nanocrystalline ATO sol and thin gel film.     

Chiral recognition in the resolution of enantiomers by GLC

Summary Chiral recognition of many enantiomeric solutes by a chiral amide stationary phase is based mainly on hydrogen bonding. A chiral-recognition-factor CHI is proposed, given by the difference of the enthalpy change in the enantiomer discrimination, standardized with respect to the specific interaction of the solutes with the diamide core of the stationary phase. The r?le of the entropy part is also discussed. By extrapolation of the retention behaviour to elevated temperature, peak inversion of enantiomers is predicted. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

Conformation control of bilatrienes by peptides: A survey

Summary A variety of bilipeptides has been synthesized and investigated by UV-VIS and CD spectroscopy to explore the conformational influence of peptide ligands on the covalently bound tetrapyrrol moiety. The results obtained are complemented by those reported previously. From the comprehensive data thus available several features of the peptidic chain regulating interactions with the bilatriene moiety have been elucidated. Accordingly, the presence of three amide linkages at the ligand is prerequiste for induction of pronounced conformational changes consisting either in a complete transition ofM intoP helical bilatriene species by inversion of all torsional angles, or in a stretching of the chromophore. The kind of conformational influence can be controlled by varying the position of the prolyl entity within a given peptide.Dedicated to Prof. Dr. Kurt Schaffner on occasion of his 60th birthday     

POLYMERIZATION MECHANISM OF N-VINYLCARBAZOLE WITH CHIRALLY ORGANIC SALT AS CATALYST

The polymerization mechanism is described by the conductance changewith the time during the polymerization. The mechanism can be explained by the equi-librium feature (i.e. main ion-pairs) between the free ions and the ion-pairs dissociated bythe organic salt (-) Sp~/(*~+) (+) CSA~(*~-) (An asterisk represents the chirality) and the schemeof the polymerization process is described mainly by the charge transfer complexes havingchiral induction power.     

7-十二烯基-8-羟基喹啉的合成

7-十二烯基-8-羟基喹啉是一种新型螯合型萃取剂(Kelex 100的主要成份)。它是(1a)和(1b)异构体的混合物。本文报道了利用1-氯-1,1,3,3-四甲基丁烷与过量丁二烯-[1,3]的1,4加成反应合成重要中间体1-氯-5,5,7,7-四甲基辛烯-[2](3)的方法,此法具有室温、常压、产率高、设备简单、操作方便等优点。