Institute of Organic Chemistry and Biochemistry of the, Czech Academy of Sciences, Flemingovo nam. 542/2, 166 10, Prague 6, Czech Republic.
Department of Inorganic Chemistry, Charles University, Hlavova 2030/8, 128 43, Prague 2, Czech Republic.
Chemistry. 2018 May 28;24(30):7601-7604. doi: 10.1002/chem.201800369. Epub 2018 May 4.
Diquats with extremely high racemization barriers with ΔG of 233 kJ mol at 180 °C are described. Reported configurational robustness is due to a combination of two structural features: the rigid o-xylylene tether connecting the nitrogen atoms and the presence of two substituents in the bay region of the bipyridinium scaffold. The straightforward synthesis of diquats, plus facile resolution and derivatization make them attractive for chiral application studies. This is demonstrated by: 1) synthesis of the first non-racemic diquat dyes with pronounced chiroptical properties, and 2) capability of diquats to interact stereospecifically with chiral molecules. This suggests potential for diquat derivatives to be used as chiral selectors in separation methods.
本文描述了具有极高外消旋化势垒的季铵盐，在 180°C 时 ΔG 为 233 kJ/mol。报道的构象稳定性归因于两个结构特征的结合：连接氮原子的刚性邻-二甲苯撑桥和双吡啶𬭩支架的海湾区域的两个取代基。季铵盐的合成路线简单，易于拆分和衍生化，使其成为手性应用研究的理想选择。这一点通过以下两个方面得到了证明：1）合成了具有显著手性光学性质的首个非外消旋季铵盐染料；2）季铵盐能够与手性分子进行立体特异性相互作用。这表明季铵盐衍生物有可能作为手性选择剂用于分离方法中。
