Wen Xin, Wang Fulin, Du Sifan, Jiang Yuqian, Zhang Li, Liu Minghua
Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences (CAS), ZhongGuanCun North First Street 2, Beijing, 100190, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Small. 2024 Sep;20(37):e2401954. doi: 10.1002/smll.202401954. Epub 2024 May 11.
Achiral solvents are commonly utilized to induce the self-assembly of chiral molecules. This study demonstrates that achiral solvents can trigger helicity inversion in the assemblies of dansyl amphiphiles and control the excited-state "majority rule" in assemblies composed of pure enantiomers, through variation of the cosolvent ratio. Specifically, enantiomers of dansyl amphiphiles self-assemble into helical structures with opposite handedness in methanol (MeOH) and acetonitrile (MeCN), together with inversed circular dichroism and circularly polarized luminescence (CPL) signals. When a mixture of MeOH and MeCN is employed, the achiral cosolvents collectively affect the CPL of the assemblies in a way similar to that of "mixed enantiomers". The dominant cosolvent governs the CPL signal. As the cosolvent composition shifts from pure MeCN to MeOH, the CPL signals undergo a significant inversion and amplification, with two maxima observed at ≈20% MeOH and 20% MeCN. This study deepens the comprehension of how achiral solvents modulate helical nanostructures and their excited-state chiroptical properties.
非手性溶剂通常用于诱导手性分子的自组装。本研究表明，非手性溶剂可通过改变助溶剂比例，引发丹磺酰两亲分子组装体中的螺旋性反转，并控制由纯对映体组成的组装体中的激发态“多数规则”。具体而言，丹磺酰两亲分子的对映体在甲醇（MeOH）和乙腈（MeCN）中自组装成具有相反手性的螺旋结构，同时圆二色性和圆偏振发光（CPL）信号发生反转。当使用MeOH和MeCN的混合物时，非手性助溶剂以类似于“混合对映体”的方式共同影响组装体的CPL。占主导地位的助溶剂控制CPL信号。随着助溶剂组成从纯MeCN转变为MeOH，CPL信号经历显著的反转和放大，在约20% MeOH和20% MeCN处观察到两个最大值。本研究加深了对非手性溶剂如何调节螺旋纳米结构及其激发态手性光学性质的理解。
