Evolution of Aqueous-Phase CdTe Magic-Size Clusters from Their Precursor Compounds

Aqueous-phase semiconductor CdTemagic-size clusters(MSCs) havenot been reported. Here, we report the first synthesis of aqueous-phaseCdTe MSCs and propose that they evolve from their nonabsorbing precursorcompounds (PCs). CdCl2 and Na2TeO3 are used as the respective Cd and Te sources, with l-cysteineas a ligand and NaBH4 as a reductant. When a 5 degrees Creaction mixture is dispersed in butylamine (BTA), CdTe MSCs evolve.We argue that the self-assembly of the Cd and Te precursors followedby the formation of the Cd-Te covalent bond inside each assemblyresults in one CdTe PC, which quasi-isomerizes to one CdTe MSC inthe presence of BTA. At higher temperatures such as 25 degrees C, thePCs fragmentize, assisting the nucleation and growth of CdTe quantumdots. We introduce a novel synthetic approach to aqueous-phase CdTePCs, which transform to CdTe MSCs in the presence of primary amines.