Effect of pendant stereostructure on backbone conformation and enantioseparation ability of helical polyacetylene-based chiral stationary phases.
Effect of pendant stereostructure on backbone conformation and enantioseparation ability of helical polyacetylene-based chiral stationary phases.
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DOI：
10.1002/chir.23414
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发表时间：
2022-01
期刊：
影响因子：
2
通讯作者：
Ge Shi;Yue Li;Xiao Dai;Jun Shen;Xinhua Wan
中科院分区：
文献类型：
--
作者：
Ge Shi;Yue Li;Xiao Dai;Jun Shen;Xinhua Wan
从市售的N-（叔丁氧羰基）-脯氨醛获得六种带有两个立构中心（S-mR、S-mS、R-mS、Rac-mS和S-mRac）或一个立构中心（S-mBn）的脯氨酸衍生的乙炔单体。在铑-二烯配合物的催化下，它们被转化为相应的光学活性螺旋聚合物S-pR、S-pS、R-pS、Rac-pS、S-pRac和S-pBn。通过核磁共振（NMR）、拉曼、紫外可见吸收、电子/振动圆二色性光谱、高效液相色谱（HPLC）和计算模拟相结合，系统探讨了悬垂物中立体中心的构型和位置与聚合物构象以及手性拆分性能之间的相关性。与聚合物主链相邻的立构中心的构型决定了螺旋构象的方向和分析物的洗脱顺序，而与聚合物主链相距较远的立构中心的构型则影响了侧链的排列和可分辨的分析物范围。在18种芳香族化合物中，S-pR能识别10种，而S-pS能识别12种。相邻或远程立体中心的外消旋化大大减少了可以分辨的分析物的范围。基于计算机模拟，S-pS比S-pR具有更大的识别空间，有利于与含有轴向手性的外消旋体的立体拟合。对映体与CSP分子间氢键的强度和数目决定了手性识别的强弱。
Six proline-derived acetylene monomers bearing either two stereocenters (S-mR, S-mS, R-mS, Rac-mS and S-mRac) or one stereocenter (S-mBn) were obtained from commercially available N-(tert-butoxycarbonyl)-prolinal. Under the catalysis of Rh-diene complex, they were converted to the corresponding optically active helical polymers, S-pR, S-pS, R-pS, Rac-pS, S-pRac, and S-pBn. The correlations between configuration and position of stereocenters in pendants with the polymer conformation as well as chiral resolution performance were systematically explored by a combination of nuclear magnetic resonance (NMR), Raman, UV-Vis absorption, electronic/vibration circular dichroism spectroscopies, high-performance liquid chromatography (HPLC), and computational simulation. The configuration of the stereocenter adjacent to polymer mainchain determined the sense of helical conformation and the elution order of analytes, while that of the remote one affected the arrangement of pendants and the scope of analytes that could be discriminated. Among 18 aromatic analytes selected, S-pR could discriminate 10, while S-pS recognized 12. The racemization of adjacent or remote stereocenters greatly reduced the scope of analytes that could be resolved. Based on computer simulations, S-pS had larger recognition space than S-pR, favoring the steric fit with the racemates containing axial chirality. The strength and number of intermolecular hydrogen bondings between enantiomers and CSPs predominantly determined the chiral discrimination.