“First Come, First Served” and Threshold Effects in a Central‐to‐Planar‐to‐Helical Hierarchical Chiral Induction
Ting Zhao, Jigao Yi, Chunhong Liu, Xiaotong Liang, Yanling Shen, Lingling Wei, Xiangyu Xie, Wanhua Wu, Cheng Yang
Abstract
Abstract Perylene diimide tethered pillar[5]arene derivatives form aggregates in non‐polar organic solvents, and the complexation of cationic amino acid ethyl ester (cAA‐OEt) with the aggregates induce a central‐to‐planar‐to‐helical chirality transfer, leading to intensive circular dichroism (CD) signals having dissymmetric factors ( g abs ) of up to 3.67×10 −2 . The hierarchical chiral induction exhibited an intriguing threshold dose effect, namely, the chiral induction does not occur in the low concentration range of cAA‐OEt but is triggered when cAA‐OEt exceeds a threshold concentration. The inhibited interconversion between the Rp and Sp conformers of pillar[5]arene, which is further restricted in the aggregation, plays a crucial role in the threshold effect. When adding enantiopure cAA‐OEt first to the threshold concentration and then adding an equal amount of the antipodal cAA‐OEt to give cAA‐OEt in racemic form, CD spectra having the same sign as the CD induced by first adding pure cAA‐OEt were induced, thus showing an unprecedented “first come, first served” effect.