A new method for studying the molecular mechanism of supramolecular chiral transfer

Chirality is everywhere in nature. The noncentral symmetry of the interface creates a congenital condition for the symmetry breaking in the process of molecular aggregation and assembly at the interface. Therefore, compared with the bulk phase, the study of interface chiral transfer and self-assembly chiral dynamics is of great significance for understanding the origin of chirality, exploring the origin of life, and preparing chiral materials.



Interfacial chiral supramolecular self-assembly is one of the research fields that have attracted much attention in recent years. It is not only closely related to chiral life systems, but also an important method to construct large functional chiral materials. Supramolecular chirality is not only related to the chirality of molecules, but also depends on the spatial arrangement of molecules. An important and difficult scientific problem in studying the formation mechanism of supramolecular chirality is to study in situ how the interface molecular chirality is transferred to the supramolecular level. So far, there is no clear answer to this question. Compared with other research methods, nonlinear optical methods have the sensitivity of in situ, interface and chiral research, and provide important technologies and methods for explaining the relationship between the structure and characteristics of chiral substances.



In recent years, with the support of relevant research projects of the National Natural Science Foundation of China, the Beijing Municipal Natural Science Foundation of China and the Chinese Academy of Sciences, Zhang Zhen, the research group of the Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, has studied the structural chirality and chirality regulation of interface supramolecular self-assembled monolayers (J. Phys. Chem. B. 2020, 124, 8179-8187) A series of research achievements have been made in the molecular mechanism of the transfer of phospholipid molecules from chiral carbon atoms to macroscopic structure chirality (J. Chem. Phys. 2022, 156, 094704), the kinetics of the induced chiral molecular assembly of interfacial chiral molecules and the molecular mechanism of chiral assembly (J. Phys. Chem. Lett. 2022, 13, 3523-3528). On the basis of these studies, recently, researchers have further explored the chiral transfer mechanism from molecular chirality center to supramolecular scale in the process of interface supramolecular chirality construction at the molecular level using self-developed nonlinear spectroscopy and imaging instruments and molecular dynamics simulation, A method for quantitative study of long-range chiral transfer of supramolecules at interfaces by nonlinear spectroscopy was established (Nature Communications. 2022, DOI: 10.1038/s41467-022-35548-z).



In this work, researchers studied the interface of amphiphilic L -/D-Gan (N, N '- bis (octadecyl) - L -/D - (anthracene-9-carboxamide) - glutamic diamide) monolayer through chiral SFG and molecular dynamics (MD) simulation, and explored in situ how chiral information is transferred between molecular groups in the process of constructing supramolecular monolayer, The orientation information of molecular groups and the number of hydrogen bonds formed by assembly were calculated. It was found that the chiral center located in the glutamic acid unit induced slight distortion of the amide group connected with it through intermolecular hydrogen bonds, and transferred the chiral to the amide group, anthracene ring and hydrophobic alkyl chain. The results show that the chiral information of the chiral center can be transferred to hundreds of molecules within the distance of 400-500 nm through the weak non-covalent interaction between molecules. This study is of great significance for understanding the relationship between molecular intrinsic chirality and supramolecular chirality.



Relevant research results were published online in the journal Nature Communications on December 14, 2022. The corresponding author of the work is researcher Zhang Zhen, and the first author is postdoctoral Zhang Yuening. Thesis link: https://www.nature.com/articles/s41467-022-35548-z





Fig In-situ exploration of long-range chiral transfer mechanism at the interface