液相色谱手性拆分机理的热力学方法研究

手性识别是分子识别的一个重要组成部分。液相色谱手性拆分机理研究有助于色谱条件的优化和新型手性固定相的设计,也有助于理解手性识别机制。本文就线性色谱与非线性色谱条件下手性拆分过程对应热力学参数的推求方法进行了评述,阐述了相关热力学参数的涵义及其在色谱保留及手性拆分机理探讨中的应用,并展望了该领域的研究前景。     

Asymmetric Epoxidation of Terminal Olefins with Binaphthyl Strapped Porphyrin Catalysts: (‐( Stacking Interaction and Steric Effects on the Enantioselectivities

将两种具有相似手性联萘空腔的手性卟啉1b和2b作为催化剂,对苯乙烯衍生物及非芳香烯烃底物进行了催化不对称环氧化反应。应用理论计算方法研究了底物同两种催化剂之间的作用机理;应用1H NMR探讨了催化剂的手性空腔结构;结果表明芳香烯烃同催化剂的手性联萘基团之间的p-p相互作用是决定该类催化剂对映选择性的重要因素,同时催化剂手性结构的立体位阻效应使该类催化剂具有良好的ee值。     

微乳电动色谱法的研究进展

微乳电动色谱(MEEKC)是一种以微乳为背景电解质,以电压为驱动力的分离技术。本文对MEEKC中的各调节参数进行了概述,重点归纳了MEEKC法在正辛醇-水分配系数测定、中药和手性化合物分离方面的应用,以及在操作技术上的新进展,如多路进样技术以及在线联用质谱检测技术等,并通过对相关文献的分析,对一直存有争议的MEEKC与胶束电动色谱(MEKC)的联系与区别进行了讨论,最后提出了MEEKC法未来的发展空间。     

氟环唑外消旋体在纤维素-三(3,5-二甲基苯基氨基甲酸酯)手性固定相上的高效液相色谱法拆分

在纤维素-三(3,5-二甲基苯基氨基甲酸酯)（CDMPC）手性固定相上,分别采用正相、反相及极性有机相色谱模式对氟环唑外消旋体进行了拆分,并考察了流动相组成在手性识别中对手性分离的影响。氟环唑在Chiralcel OD-H手性色谱柱（填充CDMPC手性固定相）上采用反相色谱模式,以甲醇-水(体积比为80∶20)为流动相,获得了最佳的拆分,其两对对映异构体的分离度Rs分别为1.64和6.50。     

Supramolecular Stuctures from Mononuclear,Binuclear and 2D Net of Copper(II) Complexes with 6‐Hydroxypicolinic Acid

First examples of transition metal complexes with HpicOH [Cu(picOH)₂(H₂O)₂] ( 1 ), [Cu(picO)(2,2′‐bpy)]·2H₂O ( 2 ), [Cu(picO)(4,4′‐bpy)_0.5(H₂O)]_n ( 3 ), and [Cu(picO)(bpe)_0.5(H₂O)]_n ( 4 ) (HpicOH = 6‐hydroxy‐picolinic acid; 2,2′‐bpy = 2,2′‐bipyridine; 4,4′‐bpy = 4,4′‐bipyridine; bpe = 1,2‐bis(4‐pyridyl)ethane) have been synthesized and characterized by single‐crystal X‐ray diffraction. The results show that HpicOH ligand can be in the enol or ketonic form, and adopts different coordination modes under different pH value of the reaction mixture. In complex 1 , HpicOH ligand is in the enol form and adopts a bidentate mode. While in complexes 2 – 4 , as the pH rises, HpicOH ligand becomes in the ketonic form and adopts a tridentate mode. The coordination modes in complexes 1 – 4 have not been reported before. Because of the introduction of the terminal ligands 2,2′‐bpy, complex 2 is of binuclear species; whereas in complexes 3 and 4 , picO ligands together with bridging ligands 4,4′‐bpy and bpe connect Cu^II ions to form 2D nets with (12³)₂(12)₃ topology.     

手性药物的酶催化不对称定向合成

手性药物目前已成为国际上新药研究的热点。手性药物及其中间体的酶催化定向合成与传统的有机合成反应相比,所需条件温和,无需强酸强碱、高温高压等极端条件,可大大降低对设备的要求,同时具备反应速度快、立体选择性高等优势,而且对环境污染小,属于绿色合成技术,因而成为制备手性化合物的最有前景的方法之一。本文主要介绍了手性药物的酶催化不对称定向合成的方式、催化机理及应用,并引入了一些最新进展情况。     

手性固定相Chirex 3001对安息香和联萘酚及其类似物的分子识别

利用分子力学方法, 建立了苯基甘氨酸型手性固定相Chirex 3001的简化模型, 并探讨了手性固定相Chirex 3001与安息香和联萘酚及其类似物的识别机制. 模拟结果表明, 固定相主体与手性客体分子识别作用的推动力主要来自于它们之间的π-π堆积、氢键和范德华等作用. 主体与(S)-构型的客体1～3结合能力强于(R)-构型的客体, 而对于客体4～6, 则是与(R)-构型的结合强于(S)-构型, 这与高效液相色谱拆分实验结果相符. 客体1～3对映体在Chirex 3001柱上的分离因子分别为1.02, 1.04和1.11, (R)-构型先被洗脱; 客体4～6对映体的分离因子分别为1.23, 1.26和1.09, (S)-构型先被洗脱.     

Synthesis and solid-state structural characterisation of Pt(II,IV) bromide complexes containing bidentate organothiomethylpyridine heteroleptic ligands

A convenient synthetic method for the preparation of organothiomethylpyridine ligands 2-(RSCH₂)C₅H₄N (R = Ph (L¹), Me (L²)), 2-MeS–6-Me-C₅H₃N (L³), and 2-MeS–4-Me-C₅H₃N (L⁴) via the initial lithiation of substituted 2-picolines followed by the nucleophilic reaction with a diorganyldisulfide is described. The complexes [PtBr₂L] (L = L¹–L⁴) have been prepared in good to high yields as yellow solids with low solubility in organic solvents. The solid state structures of the complexes have been determined, showing the spatial arrangement of the complexes to depend significantly upon varying substituents within the ligand. The complexes undergo oxidation by bromine to form the tetravalent complexes [PtBr₄(L)] (L = L¹–L⁴). The solid state structures of [PtBr₄(L²)] and [PtBr₄(L₄)] have been determined, and shown to be monomeric with the ligand chelating the platinum centre.     

P2O5/SiO2 as an Efficient Reagent for the Preparation of Z -Aldoximes Under Solvent-Free Conditions

Abstract

A facile and efficient method for the preparation of Z-aldoximes is improved by means of P₂O₅/SiO₂ reagent in solvent-free media. Advantages of this method are the use of inexpensive and selective reagent, with high yields in simple operation, and short reaction time under solvent-free conditions.