Reversible Transformations at Room Temperature among Three Types of CdTe Magic-Size Clusters

We report the first observation of the reversible transformations that occur among three types of CdTe magic-size clusters (MSCs) in dispersion at room temperature and discuss our understanding of the transformation pathway. The reversible transformations were achieved with CdTe prenucleation stage samples, which were prepared with reactions of cadmium oleate [Cd(OA)₂] and tri-n-octylphosphine telluride in 1-octadecene and were then dispersed in mixtures of toluene and a primary amine at room temperature. Three types of OA-passivated CdTe MSCs evolved, exhibiting sharp optical absorption singlets peaking at 371, 417, and 448 nm. The MSCs and their immediate precursor compounds (PCs; with no sharp optical absorption) are labeled by the MSC absorption peak wavelengths. The transformation between MSC-371 and MSC-417 has a distinct isosbestic point at ∼385 nm and that between MSC-417 and MSC-448 at ∼430 nm. Our findings suggest that these PC-enabled reversible transformations occur through a process of quasi-isomerization, transforming between PCs and their counterpart MSCs, combined with substitution reactions that cause transformation between the two involved PCs.