Surface‐Ligand Tuned Reversible Transformations in Aqueous Environments Between CdSe Magic‐Size Clusters and Their Precursor Compounds

Abstract That magic‐size clusters (MSCs) have their counterpart precursor compounds (PCs) has not been generally accepted by expertise circles. Here, experimental evidence to support this new concept is presented. With aqueous‐phase CdSe MSCs as a model system, it is shown that when the MSCs are dispersed in water containing a certain amount of L‐cysteine (Cys), the MSCs disappear slowly. Upon the addition of CdCl₂, the MSCs recover. It is proposed that after dispersing, the MSCs transform to their quasi‐isomeric, non‐absorbing PCs upon Cys addition. In the presence of CdCl₂, the PCs transform back to the MSCs due to Cys elimination. The surface ligand Cys of the MSCs plays a significant role in the reversible transformations. The present study provides compelling evidence that absorbing MSCs have their non‐absorbing PCs. The study findings suggest that the transformation between two MSCs that display absorption spectral shifts in a stepwise pattern is assisted by their PCs.