Spontaneous Chiral Self-Assembly of CdSe@CdS Nanorods

Abstract

The enantiomeric excess phenomenon in spontaneous chiral symmetry breaking (SCSB) is a crucial issue regarding the origin of homochirality in the prebiotic environment . Although the spontaneous formation of chiral inorganic compounds with chiral space groups  and lattice dislocations  has been extensively investigated, enantiomeric excess has rarely been considered, with the convention being to assume the presence of a racemic mixture. Here, we report the SCSB in the self-assembly of cadmium chalcogenide nanorods, leading to chiral biases away from the racemate. In the presence of achiral organics, helical CdSe@CdS nanorods (HCCNs) with unidirectionally rotated crystal lattices along the rod axis were stochastically formed on the epitaxial interface of the {111}_cub/{0001}_hex planes. The stability of helical dislocation structures, as supported by a theoretical analysis of their binding energies, suggested the possibility for the emergence of helical structures in an achiral environment. Hierarchical chiral films induced by simple solvent evaporation self-assembly of HCCNs exhibited spontaneous enantiomeric excess between batches, which was speculated to be originated from the enantiomeric excess seed-assembly that induce one handedness dominated system based on the majority rules.