Enantiomeric resolution of supramolecular helicates with different surface topographies
作者:Jessica M. C. A. Kerckhoffs、Jemma C. Peberdy、Isabelle Meistermann、Laura J. Childs、Christian J. Isaac、Christopher R. Pearmund、Veronika Reudegger、Syma Khalid、Nathaniel W. Alcock、Michael J. Hannon、Alison Rodger
DOI:10.1039/b614093a
日期:——
The enantiomeric resolution of an extended range of di-metallo supramolecular triple-helical molecules are reported. The ligands for all complexes are symmetric with two units containing an aryl group linked via an imine bond to a pyridine. Alkyl substituents have been attached in different positions on the ligand backbone. Previous work on the parent compound, whose molecular formula is [Fe2(C25H20N4)3]Cl4, showed that it could be resolved into enantiomerically pure solutions using cellulose and 20 mM aqueous sodium chloride. In this work a range of mobile phases have been investigated to see if the separation and speed of elution could be increased and the amount of NaCl co-eluted with the compounds decreased. Methanol, ethanol and acetonitrile were considered, together with aqueous NaCl : organic mixtures. Effective separation was most often achieved when using 90% acetonitrile : 10% 20 mM NaCl (aq) w/v, which gives scope for scaling up to incorporate the use of HPLC. The overall most efficient (i.e. fastest) separation was generally achieved where the cellulose column was packed with 20 mM NaCl (aq) and the column first eluted with 100% acetonitrile, then with 75% ethanol : 25% 20 mM NaCl (aq) until the M enantiomer had fully eluted and finally with 90% acetonitrile : 10% 20 mM NaCl (aq) until the P enantiomer had been collected. The sequence of eluents ensured minimum NaCl accompanying the enantiomers and minimum total solvent being required to elute the enantiomers, especially the second one, from the column. No helicate with a methyl group on the imine bond could be resolved and methyl groups on the pyridine rings also have an adverse effect on resolution.
本研究报告介绍了一系列二金属超分子三螺旋分子的对映体解析。所有配合物的配体都是对称的,其中两个单元含有一个芳基,通过一个亚胺键与一个吡啶相连。烷基取代基连接在配体骨架的不同位置。母体化合物的分子式为[Fe2(C25H20N4)3]Cl4,以前的研究表明,使用纤维素和 20 mM 氯化钠水溶液可以将其分离成对映体纯溶液。在这项工作中,对一系列流动相进行了研究,以确定是否可以提高分离度和洗脱速度,并减少与化合物共同洗脱的氯化钠量。甲醇、乙醇和乙腈以及氯化钠水溶液:有机混合物都在研究之列。使用 90% 乙腈:10% 20 mM NaCl (aq) w/v 时最常实现有效分离,这为使用高效液相色谱进行放大提供了空间。最有效(即最快)的整体分离通常是在纤维素色谱柱填充 20 mM NaCl(aq),色谱柱首先用 100% 乙腈洗脱,然后用 75% 乙醇 : 25% 20 mM NaCl(aq)洗脱,直到 M 对映体完全洗脱,最后用 90% 乙腈 : 10% 20 mM NaCl(aq)洗脱,直到收集到 P 对映体。洗脱液的顺序确保了对映体所附带的 NaCl 含量最低,以及从色谱柱洗脱对映体(尤其是第二种对映体)所需的溶剂总量最少。亚胺键上带有甲基的对映体都无法分辨,而吡啶环上的甲基也会对分辨产生不利影响。