Chiral magic-size clusters via direct aqueous synthesis with chiral ligands

Chiral colloidal semiconductor magic-sized clusters (MSCs) with dimensions less than 2 nm provide abundant surface binding sites for chiral ligands and thus have great potential for chiral semiconductor nanomaterial applications. However, the preparation and optical characterization of chiral MSCs are rarely reported in the past. In this study, chiral MSCs in a single-ensemble form, containing CdS MSCs with a unique sharp absorption peak at 366 nm and CdSe MSCs at 420 nm, were synthesized for the first time in aqueous solution at room temperature using chiral cysteine as ligands. The optical activity of the prepared chiral MSCs can be easily adjusted by varying the amount of chiral ligands added. The maximum absorption asymmetry factors of the prepared chiral CdS MSCs and CdSe MSCs reach 3.6 × 10−4 and 5.6 × 10−4, respectively. The experiment results indicate that the chiral optical properties of the prepared MSCs may originate from the ligand-induced atomic rearrangement on the surface of MSCs. This study not only provides a general method for obtaining chiral MSCs, but also opens the way for research and applications of chiral MSCs.