新型三唑桥联杂化复式环糊精手性固定相的构筑及性能研究

运用Cu(I)催化的1,3-偶极环加成反应(点击化学), 以乙酸酐修饰单叠氮环糊精为底层, 炔基衍生的天然环糊精为顶层, 在硅胶表面通过自下而上的方式构建了一种新型“天然-乙酰基衍生化”三唑桥联杂化复式环糊精手性固定相材料(ANCDCSP), 并通过红外光谱、热重和元素分析等测试手段对其结构进行了表征. 该固定相材料可提供包合作用、氢键给体、氢键受体、偶极-偶极作用等多重识别位点以及底层和顶层环糊精间的协同效应. 在HPLC反相分离模式下, 该固定相材料对10种丹磺酰氨基酸类(Dns amino acids)、10种小分子芳香酸(phenyl carboxylic acids)、5种异噁唑啉类(isoxazolines)以及多种其它手性对映体具有良好的手性拆分效果. 其中Dns-Phe、DL-3PhLacA以及Bendroflumethiazide的分离度分别达到5.3、4.1和4.1, 且多数手性对映体的分离度优于课题组先前制备的复式天然环糊精手性固定相(DCDCSP).     

新型环糊精手性色谱拆分材料的点击化学调控及拆分性能研究

通过点击化学方式对单叠氮环糊精进行衍生,引入具备不同作用位点的功能化基团,对环糊精手性分离性能进行调控.首先通过醚键将单叠氮环糊精接枝到硅胶表面,进一步通过Cu(I)催化的1,3-偶极环加成反应(点击化学)在环糊精小口端分别引入叔丁基、苯基、酯基和羟基基团,构建了4种新型环糊精手性固定相并通过红外光谱和元素分析对其进行了结构表征.通过高效液相色谱反相分离模式实现了异噁唑啉和丹磺酰氨基酸共16种对映体的手性拆分.酯基功能化的环糊精手性固定相对多数异噁唑啉类有良好的拆分效果,其中,2-氯苯基-异噁唑(2ClPh-OPr)分离度可达1.62.丹磺酰氨基酸类最佳分离pH值为5.0,叔丁基功能化固定相具有最好的分离效果,大部分样品可实现基线分离(Rs＞1.5).     

二脲基桥联β-环糊精手性液相色谱键合相的制备与性能评价

采用六亚甲基二异氰酸酯与6-脱氧-6-羟乙基胺基-β-环糊精反应,合成二脲基桥联β-环糊精,并将其键合到硅胶表面,制备一种新型的二脲基桥联β-环糊精固定相(UBCDP)。通过红外光谱、质谱、元素分析等进行结构表征,以黄烷酮类、氨基酸类、三唑类手性药物和农药为探针,评价其手性色谱性能,探讨相关分离机理。进行色谱条件优化,并与单β-环糊精固定相(CDCSP)比较。试验了多种手性化合物,其中25个被拆分,2′-羟基黄烷酮、己唑醇、丹磺酰亮氨酸等分离度(R_s)达到1.52～4.35,且能拆分体积较大的橙皮甙。这与桥联β-环糊精的协同包结作用有关。而CDCSP仅能拆分少量的对映体,且分离度较低。UBCDP手性拆分能力更强,在手性药物和农药监测中有应用价值。     

醇存在下R,S-1,1′-2-联萘酚对映体的环糊精手性识别研究

以R,S-1,1′-2-联萘酚对映体为手性客体分子, 采用荧光探针法详细研究了各种醇对β-环糊精/(R或S)-1,1′-2-联萘酚对映体的手性包络和手性荧光猝灭等性质的影响, 结果表明, 醇的存在可显著影响R,S-1,1′-2-联萘酚对映体与β-环糊精形成包络物的包络形式和包络常数. 通过与该对映体的β-环糊精手性固定相高效液相色谱拆分法比较研究结果表明, 醇等第三客体分子可显著影响环糊精对对映体化合物的手性选择性和分离度.     

手性选择体涂敷薄层色谱拆分盐酸普萘洛尔

采用手性选择体涂敷薄层色谱方法,拆分了盐酸普萘洛尔对映体,考察了β-环糊精、羟丙基-β-环糊精以及（2R,3R）-酒石酸-二-烷基酯等多种手性选择体拆分效果,得到手性选择体涂敷薄层色谱拆分盐酸普萘洛尔对映体最佳条件：采用β-环糊精、羟丙基-β-环糊精涂敷薄层色谱,以乙腈-仲丁醇混合溶剂作展开剂,展开剂中乙腈体积分数大于30%时,室温下展开均可拆分盐酸普萘洛尔对映体,并实现基线分离.实验同时发现,采用（2R,3R）-酒石酸-二-烷基酯涂敷薄层色谱拆分不能实现拆分.通过比较手性选择体结构,探讨了拆分机理.     

醇存在下R,S-1,1′-2-联萘酚对映体的环糊精手性识别研究

以R,S-1,1′-2-联萘酚对映体为手性客体分子, 采用荧光探针法详细研究了各种醇对β-环糊精/(R或S)-1,1′-2-联萘酚对映体的手性包络和手性荧光猝灭等性质的影响, 结果表明, 醇的存在可显著影响R,S-1,1′-2-联萘酚对映体与β-环糊精形成包络物的包络形式和包络常数. 通过与该对映体的β-环糊精手性固定相高效液相色谱拆分法比较研究结果表明, 醇等第三客体分子可显著影响环糊精对对映体化合物的手性选择性和分离度.     

新型双β-环糊精键合SBA-15液相手性固定相的制备及评价

由于桥联双β-环糊精的协同包结作用和独特的多重识别功能已被广泛地用作人工模拟酶,本文尝试用桥联双β-环糊精作固定相配体,开发其手性分离功能.采用3-异氰酸丙基三乙氧基硅烷偶联剂连续反应法,首先将（6-氧-对甲苯磺酰）-β-环糊精键合到有序介孔SBA-15硅胶表面,然后与（6-乙二胺-6-去氧）-β-环糊精反应,制备一种新型的乙二胺桥联双β-环糊精键合SBA-15液相色谱手性固定相（BCDSP）.采用质谱、红外光谱、元素分析、热重分析和透射电镜等进行结构表征.在极性有机溶剂模式下,评价了新固定相的基本色谱性能,并用于β-受体阻滞剂对映体的拆分.考察了流动相中有机溶剂、三乙胺、冰醋酸改性剂用量和柱温对手性分离的影响.基于优化的色谱条件,采用双β-环糊精键合固定相成功地拆分了常用的14种β-受体阻滞剂药物对映体,其中普萘洛尔的分离度可达到2.18,卡维地洛的分离度可达到2.01,分析时间一般为10～20 min,取得了较高的分离效率.为比较研究,还制备了一种单β-环糊精固定相（CDSP）,结果发现双β-环糊精键合相可拆分14种β-受体阻滞剂,而在优化的条件下单β-环糊精键合相仅能部分拆分4种β-受体阻滞剂,且前者的分离度明显优于后者.基于实验数据对双β-环糊精和单β-环糊精固定相的分离机理的异同点展开讨论.一方面包结作用和氢键作用在桥联双β-环糊精键合相的手性分离中占重要地位,与常见的单β-环糊精固定相相似;另一方面桥联双β-环糊精固定相拥有自身的特点,两个β-环糊精腔体存在协同作用,相应于它的模拟酶功能,协同作用不仅扩大了空间识别域,还提高了立体选择性,基于双腔体的包结作用和乙二胺桥键的氢键作用等增强了固定相的手性识别能力,加上有序的SBA-15能加快传质,使得BCDSP具有较好的手性色谱性能,拥有更广泛的拆分对象、更高的分离度和更短的分析时间.新固定相的制备方法简便,手性分离功能强,色谱性能稳定,且制备成本较低.这类桥联双β-环糊精键合有序介孔SBA-15新型的快速分离材料在手性药物质量监控和药代动力学研究中存在良好的应用前景.     

黄烷酮对映体的高效液相色谱手性拆分及含量测定

采用环糊精为手性固定相,建立了黄烷酮对映体的高效液相色谱(HPLC)手性拆分方法。考察了流动相组成、流动相比例、流速及柱温对黄烷酮对映体拆分的影响。结果表明,以CD-CSP2手性色谱柱分离,采用乙腈-水(体积比30∶70)为流动相,在流速为1.0mL/min,温度30℃,检测波长254nm下,黄烷酮对映体能达到基线分离,且具有较好的重复性和稳定性,可用于对映体的拆分及质量控制。且R-黄烷酮与固定相的作用弱于S-黄烷酮,在色谱柱中首先被洗脱。以面积归一化法计算可知黄烷酮样品中,R-黄烷酮含量为53.94%,S-黄烷酮含量为46.06%。     

二脲基桥联β-环糊精手性液相色谱键合相的制备与性能评价

采用六亚甲基二异氰酸酯与6-脱氧-6-羟乙基胺基-β-环糊精反应,合成二脲基桥联β-环糊精,并将其键合到硅胶表面,制备一种新型的二脲基桥联β-环糊精固定相(UBCDP)。通过红外光谱、质谱、元素分析等进行结构表征,以黄烷酮类、氨基酸类、三唑类手性药物和农药为探针,评价其手性色谱性能,探讨相关分离机理。进行色谱条件优化,并与单β-环糊精固定相(CDCSP)比较。试验了多种手性化合物,其中25个被拆分,2'-羟基黄烷酮、己唑醇、丹磺酰亮氨酸等分离度(R_s)达到1.52~4.35,且能拆分体积较大的橙皮甙。这与桥联β-环糊精的协同包结作用有关。而CDCSP仅能拆分少量的对映体,且分离度较低。UBCDP手性拆分能力更强,在手性药物和农药监测中有应用价值。     

毛细管电泳环糊精添加剂拆分特布他林对映体的立体选择性研究

分别测定了毛细管区带电泳环糊精手性拆分体系中α,β－环糊精和二甲基、三甲基、羟丙基－β－环糊精与药物对映体特布他林形成包结络合物的稳定常数以及手性拆分过程的热力学函数的变化。数据分析表明,环糊精稳定常数的大小反映了环糊精空腔与分离对象之间的匹配程度。环糊精稳定常数的相对值反映了手性拆分体系的分离能力。两对映体与环糊精所形成包结络合物的Δ（ΔＨ）和Δ（ΔＳ）分别反映了手性拆分过程中立体作用与构象匹配的差异。与甲基化β－环糊精相比,羟丙基－β－环糊精和β－环糊精提供的氢键作用在手性拆分中起着重要作用。     

键合型聚丙烯酰胺衍生物手性固定相的制备与手性识别性能

高效液相色谱(HPLC)被广泛认为是分离制备光学纯单一对映体的最有效方法。在高效液相色谱手性拆分中,手性固定相(CSP)的性能直接影响到色谱柱的手性分离能力。在众多手性固定相中,键合型手性固定相具有溶剂耐受性好,分离模式灵活等优点,已经发展成为一类重要的手性固定相。本文通过两步化学反应合成了新型的光学活性丙烯酰胺衍生物--(S)-1-丙烯酰-2-(N-苯基甲酰胺基)吡咯烷((S)-APACP),采用核磁共振氢谱表征了(S)-APACP的化学结构;通过3步化学反应制备了键合型聚丙烯酰胺衍生物手性固定相,采用热重分析法表征了聚合物的键合量,采用HPLC评价了键合型手性固定相的识别能力,分析了影响其手性识别能力的因素。研究结果表明,APACP聚合物成功地键合到硅胶表面制备了具有良好溶剂耐受性的键合型手性固定相,其聚合物键合量为10.2%~11.8%,该键合型手性固定相对若干种对映体显示了较好的手性识别能力。     

Separation of the enantiomers of 2-phenylcyclopropanecarboxylate esters by capillary gas chromatography on derivatized cyclodextrin stationary phases

Summary Separation of the enantiomers of 2-phenylcyclopropanecarboxylate esters has been investigated on derivatized cyclodextrin chiral stationary phases (CD CSPs) to enable direct determination of the enantiomeric purity of the products of enantioselective cyclopropanation. Four stereoisomers of these chiral compounds could be resolved to baseline on permethylated β-cyclodextrin CSP. Some unusual phenomena, iso-enthalpy retention behavior and entropically driven chiral separation, were observed for the enantioseparation of 2-phenylcyclo-propanecarboxylates on the CD CSPs. Thermodynamic parameters were evaluated and an enthalpy-entropy compensation effect was observed forn-alkyl esters of 2-phenylcyclopropanecarboxylate separated on CD CSPs.     

Enantioselective Partitioning of Racemic Ibuprofen in a Biphasic Recognition Chiral Extraction System

Enantioselective partitioning of ibuprofen enantiomers in a biphasic recognition chiral extraction system was studied. A combination of hydrophobic L‐isobutyl tartrate in organic phase and hydrophilic β‐cyclodextrin derivative in aqueous phase is necessary to establish a biphasic recognition chiral extraction system. The studies performed involve an enantioselective extraction in a biphasic system, where ibuprofen enantiomers form four complexes with the β‐cyclodextrin derivative in aqueous phase and the D(L)‐isobutyl tartrate in organic phase, respectively. In these biphasic resolutions, the types and the concentrations of the extractants, pH and temperature all exert a considerable influence on the biphasic recognition process. Good enantioselectivities for ibuprofen enantiomers were obtained at pH≦2.5 and a ratio of 2:1 of [L‐isobutyl tartrate] to [HP‐β‐CD]. Biphasic recognition chiral extraction is of strong chiral separation ability, and may be very helpful to optimize the extraction systems and realize the large‐scale production of enantiomers.     

Evaluation of two commercial capillary columns for the enantioselective gas chromatographic separation of organophosphorus pesticides

The separation of the enantiomers of 13 organophosphorus pesticides (OPPs) has been investigated by gas chromatography (GC) with flame ionisation detection (FID) using two different commercially available chiral columns, Chirasil-Val (l-valine-tert-butylamide) and CP-Chirasil-Dex CB (heptakis (2,3,6-tri-O-metil)-β-cyclodextrin). Using the Chirasil-Val column no chiral resolution was obtained for the OPPs investigated under any tested experimental condition. The use of the CP-Chirasil-Dex CB stationary phase enabled good individual enantiomeric separation of two OPPs, ruelene and trichlorfon and partial separation of naled, chloretoxyphos, isophenphos and metamidophos. Also, the obtained chromatographic results showed that Chirasil-Dex could resolve enantiomers through the combination of different mechanism (e.g. formation of inclusion complexes and/or interactions outside the cyclodextrin cavity).

Under optimised conditions, precision, linearity range and detection limits were evaluated for the enantiomers of ruelene and trichlorfon using CP-Chirasil-Dex CB column and electron capture detection (ECD). By using the GC-ECD method the enantiomers of these OPPs could be satisfactorily detected at very low concentration levels. The detection limits observed were 1.5 ng mL⁻¹ and 11.5 ng mL⁻¹ for the enantiomers of trichlorfon and ruelene, respectively.     

衍生化β-环糊精手性固定相高效液相色谱法拆分米那普仑对映体及其分离机制

建立了新型抗抑郁药米那普仑在环糊精手性固定相上的高效液相色谱拆分方法。在反相色谱条件下采用未衍生化β-环糊精(Cyclobond I 2000)、乙酰基-β-环糊精(AC-β-CD)、2,3-二甲基-β-环糊精(DM-β-CD)、3,5-二甲基苯基氨基甲酸酯-β-环糊精(DMP-β-CD)4种手性柱分离米那普仑对映体。考察了固定相、流动相比例、pH、流速和柱温对拆分的影响。利用分子对接和结合能计算方法,研究米那普仑分子与AC-β-CD的对接过程,探讨其可能的分离机制。优化后的拆分条件如下:固定相为乙酰基-β-环糊精手性柱Astec CYCLOBONDTMI 2000 AC(25 cm×4.6 mm,5μm),流动相为乙腈-0.1%(体积分数)pH 5.0醋酸三乙胺溶液(TEAA)(5∶95,v/v),流速为0.4mL/min,柱温为25℃,检测波长为220 nm。在此条件下,米那普仑对映体获得快速拆分,分离度(Rs)为1.74,理论塔板数为10 125。分子模拟结果表明引起手性识别的作用力主要是环糊精衍生化的乙酰基导致的氢键作用差异。该方法快速、高效、重现性好。     

Designed combination of chiral selectors for adjustment of enantioseparation selectivity in capillary electrophoresis.

In this study an attempt has been made to explain the reasons for changing the enantioseparation selectivity in some dual cyclodextrin (CD) systems compared to the use of single chiral selectors in capillary electrophoresis (CE). An explanation for selectivity changes is proposed based on the effect of the chiral selector on the mobility of the analyte. In order to support the proposed mechanism, several dual systems were designed on the basis of the known recognition pattern of enantiomers for individual CDs. In most cases the separation selectivity could be adjusted in a designed way. There was no experimental evidence for simultaneous binding of a given chiral analyte with both chiral selectors or of chiral recognition of an analyte complex with one CD by another CD.     

正相条件下温度和流速对衍生化环糊精键合手性高效液相色谱固定相立体异构体选择性的影响

合成了苯基氨基甲酸酯衍生化的β-环糊精键合固定相,9个α-氨基膦酸酯类化合物首次在环糊精类固定相上进行了有效拆分,研究了温度和流速对异构体选择性的影响,讨论了可能的手性识别机理.     

"Click" preparation of hindered cyclodextrin chiral stationary phases and their efficient resolution in high performance liquid chromatography

This communication reports the preparation of two new cyclodextrin (CD) chiral stationary phases (CSPs): heptakis(6-deoxy-6-azido)-β-CD and heptakis(6-deoxy-6-azido-phenylcarbamoylated)-β-CD CSPs that perform quite differently to our previously reported “click” immobilized CD-CSPs. These CSPs are sterically congested at the narrow mouth of the CD and exhibit chiral discrimination between over 40 pairs of enantiomers in high performance liquid chromatography. The free hydroxyl CSP afforded better separation of indoprofen, ketoprofen, Tröger's base, hydroxyl, carboxylic and dansyl amino acids than did the phenylcarbamoylated CSP, while the latter was better at resolving aryl alcohols, flavonoids, β-blockers and β-agonists. The current work shows that enantiodiscrimination achieved with different CSPs for different classes of analyte may be correlated with CD accessibility and peripheral functionality.     

Chromatographic evaluation and comparison of three beta-cyclodextrin-based stationary phases by capillary liquid chromatography and pressure-assisted capillary electrochromatography

Enantiomer separations were performed on three beta-cyclodextrin-based chiral stationary phases (CSP) containing the pernaphthylcarbamoylated beta-cyclodextrin (CSP 1), peracetylated beta-cyclodextrin (CSP 2) and permethylated beta-cyclodextrin (CSP 3) as chiral selectors by capillary liquid chromatography and pressure-assisted capillary electrochromatography in this study. Triethylammonium acetate/MeOH or phosphate buffer/MeOH was used as the mobile phase. The experimental factors affecting chiral separations have been examined for each CSP, including pH of the buffers, methanol content and applied voltage. Under optimal separation conditions, a number of racemic compounds were resolved into their enantiomers on three cyclodextrin-based CSP. A comparative study on the performance of three CSP revealed the presence of carbonyl functional groups as well as aromatic rings in the cyclodextrin derivatives, enhanced the interaction between the analytes and CSP, and thus improved enantioselectivity of the CSP.     

Study of chiral recognition mechanism of O,O-diethyl (p-methylbenzenesulfonamindo)-aryl(alkyl)-methylphosphonates by HPLC with a series of CSPs

Five chiral stationary phases (CSPs) were used to separate the enantiomers of a series of O,O-diethyl (p-methyl-benzenesulfonamindo)- aryl(alkyl)-methylphosphonates. A chiral recognition mechanism was presented to explain the resolution of these compounds. Results show that CSP with strong π-acceptor 3,5-dinitrobenzoyl group and high steric hindrance has the best resolution ability in chiral separation of O,O-diethyi (p-methyl-benzenesulfonamindo)- aryl(alkyl)-methylphosphonates. When a CSP has just a strong π-acceptor 3,5-dinitrobenzoyl or high steric hindrance it does not have good chiral resolution ability. The chiral recognition is more difficult when the CSP has more than one asymmetric center.