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分子烙印手性固定相分离过程热力学研究 总被引:8,自引:0,他引:8
考察了温度对分子烙印固定相手性分离的影响,计算了手性分离过程中的热力学参数.结果表明,分子烙印手性固定相的分离过程为焓控制过程.随着温度的升高,样品的容量因子降低,手性选择因子α减小.样品与分子烙印固定相的作用力包括非特异作用力和特异作用力,只有特异作用力的差值才是手性分离的本质.分子烙印产生的空穴对热力学参数有较大的影响,烙印分子与烙印空穴的匹配性最好,烙印空穴对烙印分子的结合在能量和构型上都是有利的. 相似文献
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以CuⅡ-[N-(4-vinylbenzyl)]im inod iacetic ac id为功能单体、三甲氧基丙烷三甲基丙烯酸酯为交联剂、甲醇为聚合溶剂,制备了L-扁桃酸的金属配位分子烙印聚合物。用它作为色谱固定相,系统考察了流动相的pH、甲醇含量以及缓冲溶液的浓度对其手性分离能力的影响。在中性或弱碱性(pH 7~9)流动相条件下,L-扁桃酸的金属配位分子烙印聚合物对D,L-扁桃酸的手性分离效果最好;其手性分离能力随流动相中甲醇含量和缓冲溶液浓度的增大而增强。本研究的工作为在极性溶剂中制备高选择性的分子烙印聚合物提供了实践支持。 相似文献
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采用紫外光谱法选择丙烯酰胺为功能单体,以二苯甲酰-D-酒石酸(D-DBTA)为模板分子,丙烯酰胺为功能单体,二甲基丙烯酸乙二醇酯为交联剂,甲苯和十二醇为混合致孔剂,用原位分子印迹技术,合成了D-DBTA分子印迹整体聚合物。在优化色谱条件的基础上,25min内基本实现了DBTA消旋体的手性分离,分离度达1.25。对色谱分离过程中的热力学进行分析,在所考察的温度范围内,色谱分离存在两种不同的热力学过程,且两者与范特霍夫方程能够很好地吻合。在这两种热力学过程的转换温度处,分离因子α达最大值。 相似文献
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以桑色素为模板的分子烙印聚合物的制备、结合特性及其在薄层色谱固定相方面的应用 总被引:1,自引:0,他引:1
以桑色素为模板,选用不同的功能单体和致孔剂制备了一系列分子烙印聚合物,采用结合实验考察了它们对底物的吸附特性,发现以丙烯酰胺为功能单体,以乙酸乙酯为致孔剂制得的烙印聚合物对底物有很好的选择性,同时对一些结构相似的化合物具有一定的结合力.Scatchard方程研究结果表明,在研究的浓度范围内聚合物形成了一类等价的结合位点,其平衡离解常数为0.877mmol/L,对模板分子的最大表观结合量为59.18μmol/g.可认为桑色素分子中3,7,4'位的羟基与功能单体的氢键作用是分子烙印聚合物具有底物选择性的主要因素.以该分子烙印聚合物为薄层色谱固定相,可以把模板分子从结构相似的化合物中分离出来,最小分离度为1.19. 相似文献
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以丙烯酰胺为功能单体, 以二甲基丙烯酸乙二醇酯为交联剂, 在模板分子N-叔丁氧羰酰-L-色氨酸(N-Boc-L-Trp)和N-叔丁氧羰酰-L-酪氨酸(N-Boc-L-Tyr)的存在下, 分别采用光引发聚合和热引发聚合制备了N-Boc-L-Trp和N-Boc-L-Tyr的分子印迹聚合物(MIPs), 进行分子印迹手性分离过程的热力学研究. 测定了分离过程的熵变、焓变和自由能变化. 结果显示, 在流动相中添加异丙醇或甲醇等强氢键竞争性溶剂时, 熵变对分离起到了主要作用, 而且分离过程中的溶剂化对分离的影响也非常大. 分子印迹聚合物对印迹分子和非印迹分子进行分子识别的主要作用是印迹聚合物与印迹分子匹配的三维空间结构. 相似文献
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da Silva Junior IJ Sartor JP Rosa PC de Veredas V Barreto Júnior AG Santana CC 《Journal of chromatography. A》2007,1162(1):97-102
Chromatographic separation of the chiral drugs rolipram, bupivacaine and omeprazole on a tartardiamide-based stationary phase commercially named Kromasil CHI-TBB is shown in this work. The effect of temperature on the chromatographic separation of the chiral drugs using the Kromasil CHI-TBB stationary phase was determined quantitatively so as to contribute toward the design for the racemic mixtures of the named compound by using chiral columns. A decrease in the retention and selectivity factors was observed, when the column temperature increased. Van't Hoff plots provided the thermodynamic data. The variation of the thermodynamic parameters enthalpy and entropy are clearly negative meaning that the separation is enthalpy controlled. 相似文献
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Marianna Moskaľová Oleksandr Kozlov Taťána Gondová Mariana Budovská Daniel W. Armstrong 《Chromatographia》2017,80(1):53-62
A novel series of nine chiral analogs of spirobrassinin, which have potential biological activity, was separated for the first time on three different derivatized cyclofructan chiral stationary phases in the normal phase mode. The effects of mobile phase composition, the type and concentration of polar modifier, additives, and the analyte structure on the retention and enantioseparation were studied. The results proved that for cyclofructan-based chiral stationary phases, the R-naphthylethyl carbamate cyclofructan 6 provides the best separation efficiency for the analyzed compounds. The effect of temperature on the separation was also investigated and the corresponding thermodynamic parameters were evaluated from linear Van’t Hoff plots (lnk or lnα versus 1/T). It was found that the enantioseparation was enthalpy controlled. In addition, the elution order of the enantiomers was determined in all the cases. 相似文献
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合成了手性阳离子型两亲性小分子化合物,利用圆二色谱分析了其在水中形成的自组装体的结构;以该化合物的自组装体为模板,在正丙醇和氨水的混合溶剂中制备得到了介孔二氧化硅空心球;利用扫描电镜、透射电镜、X射线衍射仪以及氮气吸附-脱附试验装置分析了二氧化硅空心球的形貌及孔结构.结果表明,两亲性小分子在水中形成的自组装体呈现手性堆积;合成的介孔二氧化硅空心球的直径约为600~800nm,壁厚约为100~150nm,其孔道垂直于球的表面,孔径约为3.0nm,比表面积约为306m2·g-1.正丙醇作为模板控制二氧化硅空心球的空腔尺寸和形貌,而两亲性小分子的自组装体作为模板控制放射状孔道的形貌和尺寸. 相似文献
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Xiaoqing Chen Weijie Yang Xinyu Jiang Feipeng Jiao Lingxing Tian 《Tetrahedron: Asymmetry》2012,23(17):1227-1233
Herein we focused on using a novel separation technology, solvent sublation, for the enantioseparation of α-cyclohexylmandelic acid (CHMA). The experiment was carried out in a conventional bubble column using d-iso-butyl tartrate (d-IBTA) and sodium dodecyl sulfate (SDS) as a chiral selector and surfactant, respectively (Fig. 7). Several important parameters influencing the separation performance, such as the type of organic phase, the pH in the aqueous phase, and the concentrations of CHMA, d-IBTA, and SDS were investigated. Under the optimal operating conditions, the enantiomeric excess and separation factor were 54.85% and 4.5, respectively. The yields of d-enantiomer and l-enantiomer were 82.20% and 38.94%, respectively. Finally, the thermodynamic properties of the separation were investigated, which indicated an enthalpy-controlled process. This technique is an efficient chiral separation method, with many advantages, such as low amounts of organic solvent and chiral selector required and easier realization of the multi-stage operation. 相似文献
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茚虫威对映体分离及手性拆分热力学研究 总被引:1,自引:0,他引:1
在纤维素-三-(3,5-二甲基苯基氨基甲酸酯)(Chiralcel OD-H)手性柱上对茚虫威对映体的分离进行了研究。考察了流动相中改性剂种类和浓度、流速及柱温对分离效果的影响,并对茚虫威对映体与固定相之间保留和分离的热力学机理进行了讨论。结果表明,以正己烷-异丙醇(85∶15)为流动相,柱温为25℃,流速1.0 mL.min-1时,茚虫威对映体能获得基线分离,分离因子(α)和分离度(Rs)分别为1.50和3.49;分别以5种体积分数均为15%的醇改性正己烷,分离因子的变化顺序为:异丁醇异丙醇乙醇正丁醇正丙醇,正丙醇的分离因子为1.67,证明醇的极性和空间位阻同时影响拆分效果;在0.4~1.1 mL.min-1的流速范围内,分离度(Rs)随着流速的增大而逐渐减小;当柱温为15~35℃时,分离因子随着温度的升高呈降低趋势,两对映体的lnα与1/T呈良好的线性关系,手性拆分过程受焓的控制。 相似文献
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Borovkov VV Lintuluoto JM Sugeta H Fujiki M Arakawa R Inoue Y 《Journal of the American Chemical Society》2002,124(12):2993-3006
Complexation mechanism, binding properties and thermodynamic parameters of supramolecular chirality induction in the achiral host molecule, syn (face-to-face conformation) ethane-bridged bis(zinc porphyrin), upon interaction with chiral monoamine and monoalcohol guests have been studied by means of the UV-vis, CD, (1)H NMR, and ESI MS techniques. It was found that the chirogenesis process includes three major equilibria steps: the first guest ligation to a zinc porphyrin subunit of the host (K(1)), syn to anti conformational switching (K(S)), and further ligation by a second guest molecule to the remaining ligand-free zinc porphyrin subunit (K(2)), thus forming the final bis-ligated species possessing supramolecular chirality. The validity of this equilibria model is confirmed by the excellent match between the calculated and experimentally observed spectral parameters of the bis-ligated species. The second ligation proceeds in a cooperative manner as K(2) > K(1) for all supramolecular systems studied, regardless of the structure of the chiral ligand used. The binding properties are highly dependent on the nature of the functional group (amines are stronger binders than alcohols) and on the structure of the chiral guests (primary and aliphatic amines have overall binding constant values greater than those of secondary and aromatic amines, respectively). 相似文献
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Functionalized Graphene as a Gatekeeper for Chiral Molecules: An Alternative Concept for Chiral Separation
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Andreas W. Hauser Narbe Mardirossian Julien A. Panetier Martin Head‐Gordon Alexis T. Bell Peter Schwerdtfeger 《Angewandte Chemie (International ed. in English)》2014,53(37):9957-9960
We propose a new method of chiral separation using functionalized nanoporous graphene as an example. Computational simulations based on density functional theory show that the attachment of a suitable chiral “bouncer” molecule to the pore rim prevents the passage of the undesired enantiomer while letting its mirror image through. 相似文献