Transforming Silver Nanoclusters from Racemic to Homochiral via Seeded Crystallization

Chirality has risen as an attractive topic in materials research in recent years, but the attainment of enantiopure materials remains a major challenge. Herein, we obtained homochiral nanoclusters by a recrystallization strategy, without any chiral factors (i.e., chiral ligands, counterions, etc.). Through the rapid flipping of configuration of silver nanoclusters in solution, the initial racemic Ag40 (triclinic) nanoclusters are converted to homochiral (orthorhombic) as revealed by X-ray crystallography. In the seeded crystallization, one homochiral Ag40 crystal is used as a seed to direct the growth of crystals with specific chirality. Furthermore, enantiopure Ag40 nanoclusters can be used as amplifiers for the detection of chiral carboxylic drugs. This work not only provides chiral conversion and amplification strategies to obtain homochiral nanoclusters but also explains the chirality origin of nanoclusters at the molecular level.