Katoono Ryo, Kawai Shunsuke, Fujiwara Kenshu, Suzuki Takanori
Department of Chemistry , Faculty of Science , Hokkaido University , Sapporo 060-0810 , Japan . Email:
Chem Sci. 2015 Nov 1;6(11):6592-6600. doi: 10.1039/c5sc02614h. Epub 2015 Aug 7.
We describe a quantitative analysis of the complexation-induced inversion of a screw-sense preference based on a conformationally dynamic double-helix structure in a macrocycle. The macrocycle is composed of two twisting units (terephthalamide), which are spaced by two strands (1,3-bis(phenylethynyl)benzene), and is designed to generate a double-helix structure through twisting about a axis in a conrotatory manner. The attachment of chiral auxiliaries to the twisting units induces a helical preference for a particular sense of ()- or ()-helicity through the intramolecular transmission of chirality to dynamic double helices. The twisting unit can also act as a binding site for capturing a guest molecule, and, in a complexed state, the preferred screw sense of the dynamic double-helix structure is reversed to exhibit the contrary preference. We quantitatively monitored the complexation-induced inversion of the screw-sense preference using H NMR spectroscopy, which enabled us to observe independently two species with ()- or ()-helicity in both the absence and presence of a guest molecule. Inversion of the screw-sense preference was induced upon complexation with an achiral guest as well as a chiral guest.
我们描述了基于大环中构象动态双螺旋结构的络合诱导螺旋方向偏好反转的定量分析。该大环由两个扭曲单元（对苯二甲酰胺）组成，它们由两条链（1,3 - 双（苯乙炔基）苯）隔开，并设计成通过绕轴以顺旋方式扭曲来生成双螺旋结构。手性助剂连接到扭曲单元上，通过手性的分子内传递，诱导对特定（） - 或（） - 螺旋方向的螺旋偏好，形成动态双螺旋。扭曲单元还可作为捕获客体分子的结合位点，在络合状态下，动态双螺旋结构的优选螺旋方向会反转，呈现相反的偏好。我们使用核磁共振氢谱（H NMR光谱）定量监测了络合诱导的螺旋方向偏好反转，这使我们能够在不存在和存在客体分子的情况下独立观察到具有（） - 或（） - 螺旋方向的两种物种。与非手性客体以及手性客体络合时均会诱导螺旋方向偏好的反转。
