Optical activity and chiral memory of thiol-capped CdTe nanocrystals

CdTe nanocrystals (NCs) passivated with chiral ligands d- and l-cysteinemethylester hydrochloride were prepared and observed to exhibit characteristic CD profiles with symmetrical mirror images depending on the chirality of the capping ligand. The optical activity of CdTe NCs is shown to originate from the distorted CdS shell including chiral capping molecules. The chirality of the NC surface is maintained even after ligand exchange with an achiral thiol, providing an unprecedented chiral memory effect.

Chiral thiol-stabilized silver nanoclusters with well-resolved optical transitions synthesized by a facile etching procedure in aqueous solutions

A novel approach of cyclic reduction in oxidative conditions has been developed to prepare a single dominant species of chiral thiol-stabilized silver nanoclusters (AgNCs). Such AgNCs, which are stable in solution for up to a few days, have been obtained for the first time. The generality of the established procedure is proven by using several enantiomeric water-soluble thiols, including glutathione, as protective ligands. The prepared AgNCs featured prominent optical properties including a single pattern of UV-vis absorption with well-resolved peaks. The chirality of the clusters has been investigated by circular dichroism (CD) spectroscopy. CD spectra displayed strong characteristic signatures in the visible range. Tentative identification of the cluster composition is discussed.