Self-assembled chiral materials from achiral components or racemates

The emergence of chirality effect at extended scales of self-assembled systems from achiral or racemic precursors has long been a matter of curiosity for scientists, because the underlying mechanisms are fundamentally significance to understand the origin of homochirality in life. However, nonselective self-assembly pathways of achiral or racemic precursors generally yield equal quantities of left- and right-handed products that do not possess any chiroptical signals under thermodynamic equilibrium states. There is a huge motivation to explore generic yet powerful methods to fabricate self-assembled chiral materials starting from achiral or racemic building blocks. This review begins by providing an overview of emerging symmetry breaking strategies, which could depart from achiral precursors or racemic mixtures and subsequently achieve enantiomeric excess without aid of external chiral selectors. This background serves as a basis for discussing recent progress in an endeavor to design unique self-assembled chiral materials from achiral or racemic monomers or polymers. A critical perspective of how to apply symmetry breaking knowledge into construct chiral materials emitting circularly polarized luminescence, representing a critical branch of biolmaging probes, is also tried to discuss in the review.