手性固定相正相高效液相色谱法拆分普萘洛尔对映体

建立了手性固定相正相高效液相色谱拆分普萘洛尔对映体的方法,考察普萘洛尔对映体在4种多糖类手性色谱柱(Chiralpak AD柱、Chiralcel OD柱、Cniralcel OJ柱和Chiralpak AS柱)(Daicel,250mm×4.6mm,10μm)上的分离行为,同时考察了流动相中醇类以及碱性添加剂二乙胺(...     

两种二苯醚类除草剂在直链淀粉液相色谱手性固定相上的拆分

以硅胶涂敷直链淀粉-三(5-氯-2-甲基苯基氨基甲酸酯)为手性固定相,对两种含有1个手性中心的二苯醚类除草剂2-甲氧基-2-{5-[2-氯-4-(三氟甲基)苯氧基]-2-硝基苯)丙酸甲酯和乳氟禾草灵,进行了色谱分离.考察了流动相中异丙醇和正己烷的体积比对乳氟禾草灵对映体分离的影响.结果显示,这2种二苯醚类除草剂可以同时在Chiralpak AY-H色谱柱上获得较好的手性拆分结果；并对农药对映体与固定相之间的保留机理进行了讨论.     

敌草胺对映体圆二色光谱表征及其水体中微量对映体含量测定

应用手性Chiralpak OJ-H柱对除草剂敌草胺进行分离,对其两个对映体用圆二色光谱进行了表征。在此基础之上,应用荧光检测器建立了测定水体中微量敌草胺对映体的测定方法。该方法外消旋体线性范围为10～100 ng·mL-1;外消旋体最低检测限为8 ng·mL-1,对映体纯的检测限为4 ng·mL-1。该方法对于测定环境水体中敌草胺的手性选择性累积具有现实意义。     

高效液相手性固定相法分离分析几个质子泵抑制剂对映体

建立了高效液相手性固定相法分离分析几个质子泵抑制剂对映体的方法。使用CHIRALCEL OD-RH色谱柱,考察了有机改性剂的种类和比例、pH、流速和柱温等因素对对映体分离分析的影响,并探讨了其分离机理。雷贝拉唑和兰索拉唑对映体可实现完全分离,泮托拉唑、奥美拉唑和泰妥拉唑可达到部分分离。     

基于功能化的金纳米的共振瑞利散射方法手性识别肉碱对映体

一种不经分离而同时测定手性对映体的简便方案是非常有趣和有用的.提出一种基于共振瑞利散射(RRS)光谱技术手性识别新方法,利用功能化的金纳米粒子(Au NPs)同时检测肉碱对映体.Au NPs的RRS强度很弱,但当Cu2+存在时,RRS强度显著增加.更有趣的是,肉碱对映体均可以降低Cu2+-Au NPs体系的RRS强度,但D-肉碱使RRS降低更多.在最优实验条件下,均有良好的线性关系并有很好的相关系数以及较低的检出限.由此,这种方法可以计算出肉碱对映体的对映体比率和对映体分数.并应用于胶囊样品中肉碱对映体混合物手性识别的研究.该方法不需要复杂的手性修饰处理,并具有简捷低消耗、灵敏度高、选择性好等优点.     

β-环糊精手性识别D/L-樟脑磺酸的NMR研究

利用高分辨液体NMR技术考察了D_2O中β-环糊精与手性药物D/L-樟脑磺酸对映体之间的相互作用, 结果表明樟脑磺酸对映体能够进入β-环糊精的疏水空腔并与之发生手性相互作用. β-环糊精能够手性识别樟脑磺酸对映体. 化学计量关系实验和2D ROESY实验结果表明, 樟脑磺酸对映体的疏水结构只能从β-环糊精疏水空腔的宽口端进入, 并形成化学计量比为1∶1的非对映体络合物.     

环糊精及其衍生物在手性药物分离中的应用

手性药物的对映体由于空间结构不同,在生物体内结合的受体不同,导致其在药理和药效上有很大的差异,因此对手性药物进行手性拆分分析研究有着非常重要的现实意义.本文综述了2000年来环糊精及其衍生物作为手性流动相添加剂在高效液相色谱法中分离手性药物的应用情况.     

β-环糊精手性识别D/L-樟脑磺酸的NMR研究

利用高分辨液体NMR技术考察了D₂O中β-环糊精与手性药物D/L-樟脑磺酸对映体之间的相互作用,结果表明樟脑磺酸对映体能够进入β-环糊精的疏水空腔并与之发生手性相互作用. β-环糊精能够手性识别樟脑磺酸对映体. 化学计量关系实验和2D ROESY实验结果表明,樟脑磺酸对映体的疏水结构只能从β-环糊精疏水空腔的宽口端进入,并形成化学计量比为1∶1的非对映体络合物.     

共振瑞利散射探针罗丹明B手性识别肉碱对映体

手性对映体广泛存在于环境和生命体中,手性识别有助于探索手性世界的奥妙和生命过程的机理。共振瑞利散射因其灵敏度高成为了手性识别的一大工具。不经分离而同时测定手性对映体则是手性识别的一大新的探索。最近,我们发现罗丹明B可以作为一种散射探针来同时测定肉碱对映体。根据偏振实验可以证明罗丹明B与肉碱反应体系的共振辐射光是由共振荧光和散射光组成。当肉碱对映体与罗丹明B反应时,罗丹明B的共振瑞利散射会有不同程度的增加。根据罗丹明B响应两种对映体RRS信号的差异,我们可以同时测定肉碱对映体。     

反相薄层色谱法添加环糊精流动相分离d、l-色氨酸

研究了用β-环糊精(β-CD)作为流动相手性添加剂，在反相C18板上分离d、l-色氨酸对映体的薄层色谱法。该法不需将色氨酸进行衍生，流动相最佳组成配比为β-CD饱和溶液：甲酸t甲醇=9:2:1(V／V／V)，最佳分离温度为50℃。d、l-色氨酸对映体相对比移值α为1．35。     

Molecular dynamics simulations of the chiral recognition mechanism for a polysaccharide chiral stationary phase in enantiomeric chromatographic separations

We use explicit-solvent fully atomistic molecular dynamics (MD) simulations, permitting all the interactions between the atoms constituting the polymeric chiral stationary phase (CSP), the solvent molecules and the drug molecule enantiomers, to better understand the chiral recognition mechanism that makes chromatographic separation possible. Using amylose tris(3,5-dimethylphenyl carbamate) (ADMPC) as prototype, three solvent systems, and ten racemates as solutes, we seek a molecular dynamics average quantity that could serve as a metric that predicts which of the two enantiomers will elute first and also correlates with the ratio of retention times for enantiomers. To better understand the molecular dynamic chiral recognition that provides the discrimination which results in the separation of enantiomers by high performance liquid chromatography, we examine the differences in hydrogen bonding lifetimes in various donor–acceptor pairs between the drugs and the ADMPC, and map out the differences in ring-ring interactions between the drugs and the ADMPC. Several MD average quantities related to hydrogen-bonding lifetimes correlate with the ratio of retention times for the enantiomers. One of these quantities provides a prediction of the correct elution order 90% of the time, and the ratios of these quantities for the enantiomers provide linear correlation (0.85 coefficient) with experimental separation factors.     

Separation of chiral molecules by temperature programmed desorption

The Monte Carlo simulation method was used to model thermal desorption of a pair of enantiomers from a solid surface with a chiral periodic pattern of active sites. The main objective of the study was to determine the optimal number of the active sites and their spatial distribution within the unit cell of the surface to achieve the most efficient separation of the enantiomers. For that purpose we tested the series of chiral patterns which were found previously for the equilibrium adsorption. Temperature programmed desorption spectra were calculated using a square lattice of adsorption sites in which the active sites were distributed spatially according to the candidate patterns. Additionally, influence of relaxation of the adsorbed layer on the relative shift of the TPD peaks of the enantiomers was assessed and the key factors affecting the chiral separation were identified.     

Adsorption on nanostructured chiral surfaces studied by the Monte Carlo method

A Monte Carlo (MC) lattice gas model of adsorption of a racemic mixture of enantiomers of 1,2-dimethylcyclopropane on a chiral surface with different spatial distribution of active sites was proposed. The calculations were performed on a square lattice for both stepped chiral surfaces and smooth surfaces with chiral patterns of active sites. The adsorbing molecules were assumed to be rigid structures of two types being mirror images one of another. Regardless of the enantiomer type, each molecule was composed of four segments occupying four lattice sites. The chiral surfaces were exposed to equimolar mixture of enantiomers whose individual equilibrium adsorption isotherms were calculated using standard Grand Canonical MC technique. The major purpose of the simulation was to examine how the structure of the surface affects separation of enantiomers, that is, to determine enantioselectivity defined as the ratio of their adsorbed amounts. Additionally, comparison of the enantioselectivities corresponding to the stepped and smooth surfaces was made.     

Chiral separation in microflows

Molecules that only differ by their chirality, so-called enantiomers, often possess different properties with respect to their biological function. Therefore, the separation of enantiomers presents a prominent challenge in molecular biology and has long been a main pursuit of organic chemistry. We suggest a new separation technique for chiral molecules that is based on the transport properties in a microfluidic flow with spatially variable vorticity. Because of their size the thermal fluctuating motion of the molecules must be taken into account. These fluctuations play a decisive role in the proposed separation mechanism.     

水溶性镧系位移试剂对羟基脯氨酸的手性识别

用¹H NMR和¹³ C NMR研究了水溶性镧系位移试剂Sm-pdta对反式-4-羟基脯氨酸的手性识别. 反式-4-羟基脯氨酸与Sm-pdta形成络合物后,其¹H NMR和¹³C NMR图谱的化学位移有所变化,手性碳附近的某些原子所对应的吸收峰裂分为2组信号,分别对应反式-4-羟基脯氨酸的两种对映异构体. 结果显示,对于反式-4-羟基脯胺酸, Sm-pdta是一个既方便又有效的手性位移试剂.     

紫外分光光度法测定配合物组成及其在手性分离中应用

采用紫外分光光度法测定了Cu(Ⅱ)和L-组氨酸二元配合物的组成及Cu(Ⅱ)与L-组氨酸和泮托拉唑三元配合物组成,研究了配合物的紫外吸收光谱性质,考察了溶液pH对配合物稳定性的影响。Cu(Ⅱ)和L-组氨酸二元配合物的组成比为1∶2,Cu(Ⅱ)与L-组氨酸和泮托拉唑三元配合物组成比为1∶1∶1,碱性条件有利于配合物的生成。该结果应用于高效液相色谱法分离泮托拉唑对映体,分离度为1.4。