Simultaneous Fabrication of P and M Helices in One-Component Chiral System by Methanol-Water Mediated Dual Assembly Pathway

Abstract

The synergetic evolution of multiple chiral structures stemmed from same building units is ubiquitous in nature and vital to living systems, but achieving it in artificial systems remains a challenge. Herein, we report a methanol-water mediated dual assembly pathway strategy for simultaneous construction of P and M helices in one-component chiral system. The conformation of l-phenylaniline derivates (LBpyF) is controlled to folded state in CH₃OH due to the hydrogen bonds as well as C-H⋅⋅⋅π interaction between LBpyF and CH₃OH. Addition of H₂O into above CH₃OH solution of LBpyF results in the simultaneous occurrence of two self-assembly pathways and double networks of P and M helices were therefore formed, due to the synchronous process of 1) self-assembly of folded LBpyF into M-helices and 2) H₂O induced unfolding of folded LBpyF molecules followed by self-assembly of them into P-helices. The bipyridine core, phenyl ring, amide unit all adapted into different stacking modes in M-helices and P-helices, and energy analysis indicated that the minority M-helices were more thermodynamically favored products. This study provides an approach to explore synergetic evolution of multiple chiral structures by manipulating the multiple assembly pathway.

Keywords: Chirality; Pathway complexity; Self-assembly; Supramolecular nanofibers.