Chemically reversible isomerization of inorganic clusters

Abstract

Cluster isomerization Structural rearrangements at the atomic scale can range from isomerization of small molecules to solid-solid phase transformations of crystals. Williamson et al. show that magic-size cadmium sulfide (CdS) crystalline clusters, which are about 2 nanometers in diameter and expose a large fraction of surface atoms capped by bidentate oleate ligands, undergo a reversible isomerization. The initial α-Cd 37 S 20 phase, which has a wurtzite-like crystal structure, isomerizes to β-Cd 37 S 20 , which has a zinc blende–like structure upon exposure to methanol, and then transforms back under vacuum. This transition is driven by distortion of the ligand shell and shifts the excitonic energy gap of the clusters. Science , this issue p. 731