Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India.
J Am Chem Soc. 2020 Dec 16;142(50):20968-20972. doi: 10.1021/jacs.0c11011. Epub 2020 Dec 7.
Self-assembly of an achiral acceptor of square-planar Pd(II) or Pt(II) ion with a symmetric donor generally yields achiral architecture or a racemic mixture of chiral assemblies. Selective formation of an enantiopure assembly in such processes is very challenging. We report here a new approach of converting a dynamic mixture of multiple homochiral assemblies to an enantiopure architecture through the interaction of a chiral guest molecule. One-pot reaction of a cationic -symmetric tripyridyl donor HNO with -[(tmeda)Pd(NO)] () [tmeda = ,,','-tetramethylethane-1,2-diamine] yielded a complex mixture of stereoisomers of a chiral octahedral cage. Surprisingly, the presence of R-BINOL as a chiral guest in the above self-assembly induced selective formation of a single enantiopure octahedral cage. S-BINOL induced formation of the other enantiomer of the cage selectively. While selective recognition of an enantiomeric guest from a racemic mixture by a chiral host is well-known, present observation of "reverse chiral recognition" where the guest molecule determines the handedness of the host leading to the formation of an enantiopure cage is noteworthy.
具有对称给体的非手性受体与平面正方形 Pd(II) 或 Pt(II) 离子的自组装通常产生非手性结构或手性组装体的外消旋混合物。在这些过程中选择性地形成对映纯组装体非常具有挑战性。我们在这里报告了一种通过手性客体分子的相互作用将多种同手性组装体的动态混合物转化为对映纯结构的新方法。阳离子对称三吡啶给体 HNO 与 -(tmeda)Pd(NO) [tmeda = 二(三甲基甲硅烷基)乙二胺] 的一锅反应产生了手性八面体笼的立体异构体的复杂混合物。令人惊讶的是，在上述自组装中存在 R-BINOL 作为手性客体诱导了单一对映纯八面体笼的选择性形成。S-BINOL 诱导选择性形成笼的另一种对映体。虽然手性主体从外消旋混合物中对映选择性地识别客体是众所周知的，但目前观察到的“反向手性识别”，其中客体分子确定主体的手性，导致形成对映纯笼是值得注意的。
