Towards homochiral supramolecular entities from achiral molecules by vortex mixing-accompanied self-assembly.

Yutao Sang,Dong Yang,Minghua Liu,Pengfei Duan

doi:10.1039/c8sc04687e

Abstract

Achieving homochirality is challenging both at the molecular and the supramolecular levels. While the origin of molecular homochirality still remains mysterious, the fabrication of homochiral assemblies from achiral molecules has attracted considerable interest since it provides many clues to understand the origin of molecular chirality. Here, by using a vortex mixing-accompanied self-assembly strategy, we obtained near-unity homochiral entities with controlled handedness from supramolecular gels that consist of exclusively achiral molecules without any chiral additives. The common supramolecular gelation process via heating and cooling of the achiral molecules only resulted in racemic gels. However, if vortex mixing is applied during the self-assembly, near-unity homochiral assemblies with uncontrolled handedness were obtained. Vortex mixing during the nucleation stage was found to be crucial in this case. On the other hand, if a small amount of the above vortex mixing produced assemblies was added as chiral seeds into the racemic gels, the racemic gels turned into near-unity homochiral suspensions with controlled handedness via a ripening process. Our studies provide an intriguing approach for achieving homochiral supramolecular assemblies from achiral molecules.

Highlights

Homochirality in biological systems, wherein almost all of the amino acids and sugars found in living organisms are L- and Denantiomers, respectively, is one of the most mysterious phenomena found in life.[1,2] The origin of such molecular homochirality still remains unknown
If a small amount of the above vortex mixing produced assemblies was added as chiral seeds into the racemic gels, the racemic gels turned into near-unity homochiral suspensions with controlled handedness via a ripening process
If no external stimulation was applied during the cooling process, supramolecular gels were formed again with almost negligible circular dichroism (CD) signals, which was similar to the instant gels

Summary

Introduction

Homochirality in biological systems, wherein almost all of the amino acids and sugars found in living organisms are L- and Denantiomers, respectively, is one of the most mysterious phenomena found in life.[1,2] The origin of such molecular homochirality still remains unknown. By using a vortex mixing-accompanied self-assembly strategy, we obtained near-unity homochiral entities with controlled handedness from supramolecular gels that consist of exclusively achiral molecules without any chiral additives.

Results

Conclusion