From Magic Size to Atomic Precision: Facile Synthesis of a CdTe Semiconductor Nanocluster.

Facile synthesis of atomically precise semiconductor nanoclusters remains an important challenge, especially for those with heavier chalcogens. Combining coordination and colloidal methods, we developed a simple approach for synthesizing an atomically precise CdTe nanocluster with high purity and stability. Specifically, a precise cadmium-thiolate compound, [Cd4(SR)9]n, was reacted with a facile phosphine telluride (TePR3) precursor to produce a CdTe magic-sized cluster with a distinct absorption peak at 377 nm and a narrow linewidth of 20 nm. X-ray crystallography reveals the cluster is Cd32Te14(SR)36(PR3)4, a homologue of Cd32S14 and Cd32Se14 reported about three decades ago, thus filling the missing link in this family. The cluster features a zincblende core in a truncated tetrahedron shape. While the core is achiral, chirality emerges from the rotational stacking of surface ligands. The left and right enantiomers self-assemble into a highly ordered, atomically coherent cubic superlattice, leading to a rare racemic crystal coined as "kryptoracemate." This method provides an accessible platform for further atomic engineering of CdTe and related nanoclusters toward their target applications.